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2nd NATIONAL CATALYSIS CONFERENCE – 18-21 June 2008, Palandöken, Erzurum - TURKEY

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TECHNICAL PROGRAM

18.06.2008 - Wednesday 13:00 – 17:00 Public Seminars from Catalysis Society at

Atatürk University

J.W. (Hans) Niemantsverdriet Emrah Özensoy

Eindhoven University of Technology Bilkent University

15:00 – 18:00 REGISTRATION

18:00 – 20:00 OPENING COCKTAIL

19.06.2008 - Thursday 09:30 – 10:20 Opening Remarks

10:20 – 10:40 Coffee Break

Catalyst Preparation, Characterization and Regeneration Session chairs: Işık Önal, Emrah Özensoy

10:40 – 11:20 Invited Lecture: Catalysis and surface science: How much do we understand?

J.W. (Hans) Niemantsverdriet Eindhoven University of Technology

11:20 – 11:40 Mechanical-chemical activation of Ni-Mo/γ-alumina catalysts for hydrodesulphurization

Stanislava Andonova, Chavdar Vladov, Ivan Mitov, Lychezar Petrov

Bulgarian Academy of Sciences

11:40 – 12:00 Characterization of Nb2O5-ZrO2 mixed oxides synthesized from Nb(V) peroxo precursor as novel solid acids

Margarita Kantcheva, Olga Samarskaya, Hülya Budunoğlu, İlknur Çayırtepe

Bilkent University

12:00 – 12:20 Catalysis aspects of carbon nanofiber and nanotube production

Ahu Gümrah Dumanlı, Fatma Dinç, Ömer Faruk Mutaf, Taner Aytun and Yuda Yürüm

Sabancı University

12:20 – 12:40

Preparation of nanofiber catalysts by electrospinning

Özge Güvenir, *Oğuz Bayraktar PETKİM, *İzmir Institute of Technology

12:40 – 13:40 Lunch Break

Environmental Catalysis Session chairs: Yuda Yürüm, Selahattin Yılmaz

13:40 – 14:20

Invited Lecture: Redox catalysis with nanocrystalline zinc oxide

K. Kähler, J. Strunk, H. Noei, Y. Wang, X. Xia*, M. Muhler

Ruhr-University *University of California at Berkeley

14:20 – 14:40

NO2 and Dimethyl Ether (DME) reaction on Al2O3 as a catalyst

Emrah Özensoy, *D Herling, *Janos Szanyi

Bilkent University, *Pacific Northwest National Laboratory

14:40 – 15:00 Structural characterization and activity for ethanol electro-oxidation of carbon supported Pt–Sn bimetallic catalysts prepared by polyol method

Hilal Kıvrak, *Sadig Kuliyev, Deniz Üner

Middle East Technical University, *Vestel Defence Industries

15:00 – 15:20 Microwave assisted preparation of Pt based catalysts for PEMFCs

Ayşe Bayrakçeken, Lemi Türker, İnci Eroğlu

Middle East Technical University

15:20 – 15:40

Influence of ion-exchange resin catalysts on the reaction of the esterification of iso-butanol with propionic acid

Alime İzci, Halit Levent Hoşgün Osmangazi University

15:40 – 18:30

Poster Session


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20.06.2008 - Friday

Catalyst Preparation, Characterization and Regeneration Session chairs: A. Erhan Aksoylu, Lemi Türker

09:00 – 09:40 Invited Lecture: Propylene epoxidation on silver: A density functional study

Mehmet Ferdi Fellah, Işık Önal Middle East Technical University

09:40 – 10:00 Density functional modeling of CO oxidation over unsupported Au

Tuğba Davran-Candan, A. Erhan Aksoylu, Ramazan Yıldırım

Boğaziçi University

10:00 – 10:20

Characterization and EIS analysis of 8YSZ nano particles prepared via reverse micelle

S. Vatansever, F. Öksüzömer, S. N. Koç, *M. Somer, H. Deligöz, M. A. Gürkaynak

İstanbul University, *Koç University

10:20 – 10:40 Coffee break

Stream 1 – Industrial Catalysis

Session chairs: Erdoğan Alper, Gürkan Karakaş

10:40 – 11:00 Sanayi Ar-Ge teşvikleri

Ziya Karabulut Sanayi Bakanlığı

11:00 – 11:20 TÜBİTAK KAMAG Mustafa Ay

TÜBİTAK

11:20 – 11:40

Catalysis in Petroleum Refineries

Miray Mert

TÜPRAŞ

11:40 – 12:00

Catalysis In Petrochemical Industries

Nilüfer Yalçın PETKİM

12:00 – 12:20

Catalysis in Bulk Chemicals Industries

Refik Onur AKKİM

Stream 2 – Energy Technologies Platform Session chairs: Deniz Üner, Zeynep İlsen Önsan

10:40 – 12:10 Panel Discussion

12:10 – 13:10 Lunch

SIGHTSEEING TOUR


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21.06.2008 – Saturday Catalyst Preparation, Characterization and Regeneration

Session chairs: Timur Doğu, Ramazan Yıldırım 09:00 – 09:40 Invited Lecture: Hydrogen production

from natural gas Sonia Damyanova Bulgarian Academy of

Sciences

09:40 – 10:00 Semi-conductor Metal oxide thin film glazes for ceramic tiles and glasses with photocatalytic self-cleaning activity

Tuğçe İrfan Ersöz, Burcu (Koç) Haskılıç, Beril Korkmaz, Gürkan Karakaş

Middle East Technical University

10:00 – 10:20 Synthesis and characterization of micro-mesoporous mixed-PILCs with varying pillar density

Nurgün Beşün, İlyas Deveci, Lütfi Erden, Hanife Erden

Muğla University


Environmental Catalysis Session chairs: Timur Doğu, Ramazan Yıldırım

10:40 – 11:00 Effect of heat treatment on the activity of heteropoly acid catalysts in ETBE synthesis

Levent Değirmenci, Nuray Oktar, Gülşen Doğu

Gazi University

11:00 – 11:20 Kinetics of low temperature CO oxidation over activated carbon supported Pt-SnOx catalysts

Seda Acun, Şeyma Özkara-Aydınoğlu, A. Erhan Aksoylu, Z. İlsen Önsan

Boğaziçi University

11:20 – 11:40

Investigation of the microwave effect on catalyst synthesis for PEM Fuel Cells

Evren Oğur, Furkan Dündar, Aylin Aytaç, Ali Ata

Gebze Institute of Technology

12:00 – 13:00 Lunch Break

Oil, Gas and Petrochemicals Session chairs: Gülşen Doğu, Ayşe Nilgün Akın

13:00 – 13:20

The effect of Ce loading and impregnation Strategy on methane dry reforming activity of Ce promoted Pt/ZrO2

Şeyma Özkara-Aydınoğlu, *Emrah Özensoy, A. Erhan Aksoylu

Boğaziçi University *Bilkent University

13:20 – 13:40

Methanol dehydration reaction to produce clean diesel alternative dimethylether

Dilek Varışlı, Kenan Cem Tokay, Ayşegül Çiftçi, Timur Doğu, *Gülşen Doğu

Middle East Technical University, *Gazi University

13:40 – 14:00 Catalytic combustion of methane and hydrogen over precious metal monolith type catalyst

Alper Sarıoğlan, Özgür Can Korkmaz, Aslı Kaytaz, Atilla Ersöz, Fehmi Akgün

TÜBİTAK MAM Energy Institute

14:00 – 14:20 Partial regeneration of Ni-based catalysts for hydrogen production via methane cracking: Modeling and optimization

Reyyan Koç, Erdoğan Alper, *Eric Croiset, *Ali Elkamel

Hacettepe University, University of Waterloo

14:20 – 14:40

Development of active and selective catalysts for oxidative dehydrogenation of propane

Hilal Aykaç, *Selahattin Yılmaz PETKİM, *İzmir Institute of Technology


15:00 – 17:00

General Assembly Meeting


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LIST OF POSTER PRESENTATIONS

Poster No. Title Authors 1 Production of Ethyl Acetate Using Hetero-Poly Acid

Incorporated MCM-41 Type Catalysts

Yeşim Güçbilmez, Selime Varlı, Sibel Aslan, Halit L. Hoşgün

2 Catalytic Degradation of Polypropylene with SBA-type Catalysts

Zeynep Obalı, Naime Aslı Sezgi, Timur Doğu

3 Mesocellulous Silica Foam (MCF) Supported V-Ce Mixed Metal Oxide for Selective Oxidation Reactions

Özge Aktaş, Sena Yaşyerli, Gülşen Doğu, Timur Doğu

4 Dry Reforming of Methane Over Pd-Ni-MCM-41 Dual Catalysts

Canan (Şener) Martı, Katia ARISHTIROVA, R.N. NIKOLOV, Timur Doğu, Gülşen Doğu, Sonia DAMYANOVA

5 Mesoporous Cu-Zn-Al Incorporated Mesoporous Catalysts for Direct Synthesis of Dimethylether from Synthesis Gas

Ayça Arınan, Dilek Varışlı, Zeynep Obalı, Timur Doğu

6 Partial Oxidation of Benzene to Phenol with Nitrous Oxide on Fe- and Co-ZSM-5: A Density Functional Study

Mehmet Ferdi Fellah, Işık Önal

7 Etherification of Glycerol by Tert-Butyl Alcohol Catalysed by Ion Exchange Resin

Nalan Özbay, Nuray Oktar, Gülşen Doğu, Timur Doğu

8 Synthesis of NOx trap Catalysts Using Impregnation Technique

Emine Kaya, Nuray Oktar, Gürkan Karakaş, Kırali Murtezaoğlu

9 Catalytic Activity of V-Fe Mixed Oxide Catalyst for Selective Oxidation of H2S

Dolunay Eslek Koyuncu, Sena Yaşyerli, Zeynep Özaydın

10 In situ FT-IR Studies of Urea Decomposition over Ag/Alumina

H. Mehmet Taşdemir, Nail Yaşyerli

11 Acetalization of glycerol with valeraldehyde using Amberlyst 15 resin as a catalysts

Halit Levent Hoşgün, Mehmet Yıldız, H. Ferdi Gerçel

12 Dielectric properties of HCl acid treated bentonite samples

Ertuğrul İzci, Alime İzci

13 Selective CO Oxidation over supported CuOx Catalysts Emel Özdemir, Akif Gülbağ, Emre Özyılmaz, Ayşe Nilgün Akın

14 Direct Oxidation of Hydrogen to Hydrogen Peroxide over CuOx/SiO2 Catalysts

Meltem Yıldız, Ayşe Nilgün Akın

15 Development of Alumina Supported Alkaline Catalysts Used for Biodiesel Production

Oğuzhan İlgen, Ayşe Nilgün Akın

16 WO3-Nb2O5 solid solutions: Synthesis and Characterization

İlknur Çayırtepe, Margarita Kantcheva

17 Reactivity of Adsorbed NOx Species toward Methane on Mesoporous High Zirconia Co(II)- and Pd(II)-Modified Silica-Zirconia Materials

Olga Samarskaya, Ömer Dağ, Margarita Kantcheva

18 Investigation of Biodiesel Production from Canola Oil Using Amberlyst-26 Catalyst

Oğuzhan İlgen, Ayşe Nilgün Akın, Nezahat Boz

19 Thermal Behavior of BaO/γ-Al2O3 and Fe promoted BaO/γ-Al2O3

Emine Kayhan, Göksu Seda Şentürk, Stanislava Andonova, Emrah Özensoy

20 Direct Oxidation of Methane to Methanol by N2O on Fe- and Co-ZSM-5: A Density Functional Study


21 A Novel Material with a Novel System in the Stoichiometric and Separate Evolution of H2/O2 from the Splitting of Water

Osman Karslıoğlu, Sadig Kuliyev, Deniz Üner

22 NOx Abatement in Diesel Engine by NOx Storage and Reduction (NSR) Technology

Başar Çağlar, Deniz Üner

23 What are the active sites of a commercial 5% Pt γ-Al2O3 catalyst in liquid phase reactions?

Hilal Kıvrak, Zoltan Kiraly, Agnes Mastalir, Deniz Üner

24 Photocatalytic Reactivity of Crystalline and Fractal TiO2 films

Mehmet Mert Oymak, Osman Karslıoğlu, Deniz Üner


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25 Sonolytic, Photocatalytic and Sonophotocatalytic degradation of dyestuffs

Tuba Yetim, Taner Tekin

26 Kinetic Studies of Incorporation of Titanium in Mesoporous Silica SBA-15

Orçun Ergün, Ayşen Yılmaz, Deniz Üner

27 Biodiesel production from Canola oil over basic heterogeneous catalysts

Selahattin E. Umdu, Sait C. Sofuoğlu, Erol, Şeker

28 MCM-41 Type Catalytic Materials via Impregnation and Microwave Assisted Synthesis Methods

Aslı Nalbant, Yuda Yürüm

29 Graphene: A New Approach for the Nanostructured Electrocatalysts in Fuel Cells, A Preliminary Attempt

Burcu Saner, Yuda Yürüm

30 Kinetics of pitch and phenolic resins pyrolysis

Firuze Okyay, Yuda Yürüm

31 Removal of Boron from Water by Natural Adsorbents

Seren Yüksel, Yuda Yürüm

32 A Parametric Study of Low-Temperature Water-Gas Shift Reaction

Özlem Şen, Ahmet Kerim Avcı, Zeynep İlsen Önsan

33 Intrinsic and Extrinsic Catalysis for Lignite Gasification

Arzu Kanca, Deniz Üner

34 Synthesis of SBA-15 silica products for the production of mesoporous carbons

Aysun Karaoğlu, Asli Nalbant, Yuda Yürüm

35 Low Temperature CO Oxidation over Activated Carbon Supported Pt-CeOx

Berrin Gülyüz, A. Erhan Aksoylu, Z. İlsen Önsan

36 Synthesis of Pt /Co-Pb/SBA15 mesoporous catalysts and characterization of the samples with TPR technique

Mukaddes Can, Ayşen Yılmaz, Deniz Üner

37 Synthesis Gas Production by Dry Reforming Of Methane over Nickel Based Mesoporous Catalysts

Hüseyin Arbağ, Sena Yaşyerli, Nail Yaşyerli, Gülşen Doğu

38 Investigation of fuel properties of biodiesel produced over Alumina-based solid catalyst

Nezahat Boz, Miray Kara, Ertan Alptekin, Nebahat Değirmenbaşı

39 Propylene epoxidation: High-throughput screening of silica and alumina supported silver and copper catalysts combinatorially prepared by rapid sol-gel method

Işık Önal, Derya Düzenli, Anusorn Seubsai, Michael Kahn, Erol Seker, Selim Senkan

40 FT-IR Spectroscopic Study of Triethyl Phosphate Adsorbed on 3a and 4a Zeolites

Belgin Bardakçı, Neslihan Kaya

41 Comparative study of selective CO oxidation over Pt-Co-M/Al2O3 catalysts (M=Ce, Mg, Mn, Zr, Fe) in hydrogen-rich streams: Effects of second promoter

K. Erdem Uğuz, Ramazan Yıldırım

42 Enzyme Immobilization on Gold Modified Thin Film Surfaces Zeynep Eker, Merve Çınar, Gürkan Karakaş, Ufuk Bakır

43 Photocatalytic Activity of Titania–Silica Mixed Oxides Prepared with co-Hydrolyzation in Acidic and Basic Media

Bilal Bayram, Alp Yürüm, Gürkan Karakaş

44 Cellobiose Hydrolysis using Sulfated Zirconia Doped SBA-15 type Mesoporous Silica

Başak Cinlar, Volkan Değirmenci, Ayşen Yılmaz, Brent Shanks, Deniz Üner

45 Comparative study of preferential CO oxidation over monolithic and particulate Pt-Co-CeO2-Al2O3 catalysts

Yasemin A. Döker, Sadi T. Tezcanlı, Ramazan Yıldırım, Zeynep İlsen Önsan

46 Preferential CO oxidation over promoted Au/γ-Al2O3 catalysts

Sadi T. Tezcanlı, Ramazan Yıldırım

47 Water-Gas Shift Reaction over Bimetallic Pt-Ni/Al2O3 Catalysts

Burcu Selen Çağlayan, A. Erhan Aksoylu

48 The Effect of Ni:Pt Ratio on Autothermal Reforming Performance of Pt-Ni/Al2O3 Catalyst

Feyza Gökaliler, Bayram Ali Göçmen, A. Erhan Aksoylu

49 Performance Analysis for 2-Propanol and Direct Methanol Fuel Cells Based on Pt Containing Anode Electrocatalysts

N. Alper Tapan, Ezgi Öztürk

50 Improving the Photocatalytic Activity of TiO2 by Photon Up-Conversion

D.Doğu, B. Korkmaz Erdural, G. Karakaş


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ABSTRACTS


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INVITED LECTURES

Catalysis and Surface Science: How Much Do We Understand?

J.W. (Hans) Niemantsverdriet

Schuit Institute of Catalysis

Eindhoven University of Technology P O Box 513, 5600 MB Eindhoven

[email protected] The Nobel Prize for Gerhard Ertl’s impressive oevre in catalytic surface chemistry marks the maturity of the surface science - single crystal approach to heterogeneous catalysis. Indeed, catalysis in 2008 would not be what it is now without the insights provided by experimental and computational surface science [1]. Nevertheless, the way in which surface science is applied nowadays has changed considerably over the last 15 years, notably owing to the advent of the local probe techniques, and the advent of computational methods. Also the awareness that the beautiful single crystal surfaces are hardly as ideal as one would hope, and the non trivial translation of idealized situations to the real world of catalysis have played an important role. This talk will address the role of surface science in modern catalysis and discuss how the much better accessible supported model systems have taken the lead over the idealized surfaces of single crystals. Examples are mostly taken from our own work on hydrotreating, automotive exhaust, polymerization and Fischer-Tropsch catalysis. [1] I. Chorkendorff and J.W. Niemantsverdriet, Concepts of Modern Catalysis and Kinetics, Wiley-VCH, Weinheim, 2003 and 2007.


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Redox Catalysis with Nanocrystalline Zinc Oxide

K. Kählera, J. Strunka, H. Noeia, Y. Wanga, X. Xiaa,b, M. Muhlera,*

aLaboratory of Industrial Chemistry, Ruhr-University Bochum,44801 Bochum, Germany bDepartment of Chemical Engineering, University of California at Berkeley, Berkeley, CA 94720, USA

*Corresponding author: Fax number: +49 (0)234-32-14115, E-Mail: [email protected]

Introduction Zinc oxide is catalytically active for redox reactions, and it has always been part of industrial methanol

synthesis catalysts.1 Within the collaborative research center SFB 558 the surface properties of nanocrystalline ZnO were characterized with respect to their functions in methanol synthesis and steam reforming. Adsorption and reaction of CH3OH, CO, CO2, H2O, and H2 on ZnO powder samples were studied by a combination of IR spectroscopy, TPD, and microcalorimetry to characterize active sites and reaction intermediates. The nature of the surface OH groups was elucidated. Studies under industrially relevant conditions were completed by model studies in UHV.

Experimental TPD and IR measurements were performed in an all stainless-steel set-up with different reactor units,

comprising a glass-lined stainless steel U-tube and a DRIFTS reaction chamber. Fast online gas analysis was performed by a calibrated quadrupole mass spectrometer. UHV-IR measurements were carried out using an IR spectrometer combined with an UHV system. Heats of adsorption were measured in a home-made Tian-Calvet microcalorimeter set-up. Samples were transferred into the measurement chamber without contact to air.2

Results and discussion IR studies of H2O and D2O adsorption on nanocrystalline ZnO powder under continuous flow conditions

allowed the assignment of the various OH stretching vibrations to the different exposed ZnO surfaces.3 UHV-IR spectroscopy supported these assignments. The formation of Zn-H and O-H stretching bands, observed after dissociative hydrogen adsorption on oxidized ZnO, was analyzed with a kinetic model based on the heating rate variation method. Adsorption of CO following H2 adsorption led to a shift of the Zn-H, O-H (Type I) and C≡O stretching bands. A splitting of the ν(Zn-H) band provided information about the adsorption sites of CO and hydrogen.4 At 323 K, the subsequent exposure of ZnO first to H2 and then to CO led to the formation of formate and methoxy species, which blocked sites for further H2 adsorption.

Methanol adsorption on oxidized or H2-reduced ZnO samples caused a replacement of OH groups on different exposed ZnO surfaces by methoxy species, leading to the formation of formate species on different ZnO surfaces during heating. In this TPD and IR study, oxidized samples served as model systems, allowing to solve the mass balance and to rationalize the results obtained with the reduced samples, which are closer to industrial conditions. On H2-reduced ZnO, formate and methoxy species were formed during exposure of the sample to CO/H2 at 573 K and 5 bar. Microcalorimetric studies revealed the influence of OH groups on the adsorption of CO2. Initially, the adsorption was non-activated, whereas at higher coverages an inhibiting effect due to residual hydroxyl groups was observed.5 When CO was adsorbed, mainly weak adsorption sites were found on the exposed ZnO surfaces. In addition, different surface reactions occurred on a minor amount of highly active sites, presumably oxygen vacancies, which are influenced by the pretreatment.6 4. Conclusions

The formation of formate and methoxy species was observed both from CO and H2 and during the decomposition of methanol, which is strong evidence for their role as surface intermediates in methanol synthesis and reforming over ZnO. The quantitative calorimetry results clearly indicate that just a small amount of highly active sites accounts for the catalytic properties of ZnO. References 1. M. Kurtz, J. Strunk, O. Hinrichsen, M. Muhler, K. Fink, B. Meyer, Ch. Wöll, Angew. Chem. Int. Ed., 44 (2005) 2790 2. R. Naumann d’Alnoncourt, M. Bergmann, J. Strunk, E. Löffler, O. Hinrichsen, M. Muhler, Thermochim. Acta 434 (2005) 132 3. H. Noei, Y. Wang, H. Qiu, E. Löffler, Ch. Wöll, M. Muhler, J. Catal. to be submitted 4. F. Boccuzzi, E. Garrone, A. Zecchina, A. Bossi, M. Camia, J. Catal. 51 (1978) 160 5. X. Xia, J. Strunk, W. Busser, R. Naumann d’Alnoncourt, M. Muhler, J. Phys. Chem. C submitted 6. X. Xia, J. Strunk, R. Naumann d’Alnoncourt, W. Busser, L. Khodeir, M. Muhler, J. Phys. Chem. C submitted


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Propylene epoxidation on silver: A density functional study


Middle East Technical University, Department of Chemical Engineering, Ankara, Turkey [email protected]

Grant and Lambert carried out fundamental experimental studies using primarily Ag 111 and Ag 110 single crystals which provided evidence for the key role of atomic rather than molecular oxygen in both the epoxidation and combustion reactions. In this study, preliminary calculations of atomic oxygen adsorption followed by reaction with propylene from the gas phase on a 5 Ag atom cluster simulating Ag(111) surface were carried out using DFT/B3LYP method with basis sets composed of LANL2DZ for silver and 6-31G** for carbon, oxygen and hydrogen as implemented in Gaussian’03. Relative energy profiles as functions of a chosen reaction coordinate were calculated and two distinct pathways, one directly leading to propylene oxide (PO), and the other forming a Π-allyl radical were identified. The heat of adsorption value for atomic oxygen obtained is 64.66 kcal/mol. The next step along the reaction coordinate is the adsorption of propylene onto the oxygen-covered Ag surface. The final geometry of PO formation is found at a relative energy value of -29.12 kcal/mole. Approximate transition state energy barriers indicated a more favorable route for the case of Π-allyl radical formation (6.21 kcal/mole) as opposed to PO formation (12.29 kcal/mole). DFT calculations indicate that Π-allyl radical formation is a more favorable route as opposed to direct propylene epoxidation on Ag(111) surface. Since Π-allyl radical leads to combustion products which lower PO selectivity, this mechanistic result explains why Ag(111) surface is not a good catalyst for this reaction which is in line with experimental observations.


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Hydrogen production from natural gas

Sonia Damyanova

Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria [email protected]

Theforecastsshowthathydrogenwillbecomeamajorsourceofenergyinthefuture.Hydrogen

is ‘thefuelofthefuture’.Hydrogenoffersapotentiallynon‐polluting, inexhaustible,efficient,andcostattractivefuel forenergydemands.This means that the environmental benefit of using hydrogen depends upon how the hydrogen is produced. Theefforts arededicated todeveloppractically andeconomicallycompetitive hydrogen technologies and systems tomeet the energy needs. The natural gas accountsalmost50%oftheworld’sfeedstockforhydrogenproduction.Themainprocessesusedforconversionofnaturalgastohydrogenaresteammethanereforming,reformingofmethanewithcarbondioxideordryreforming,partialoxidationandautothermalreformingofmethane.Steam reforming of natural gas is currently the cheapest way to produce hydrogen, and accounts for about half of the world’s hydrogen production.

The most widely used catalysts for catalytic reforming processes of methane for hydrogen production are supported-Ni catalysts due to their low cost and high conversion. However, these catalysts deactivate quickly caused by the formation of coke on the surface of the active phase, poisoning and structural transformation, sintering and recombination of the active components. Catalysts based on noble metals are less sensitive to coking compared to nickel-based catalysts. However, when one considers the high cost and limited availability of noble metals, it is more practical, from the industrial standpoint to develop Ni-based catalysts able to resist carbon deposition during the reaction. More efficient hydrogen production methods will require more efficient catalysts. The challenge is to find inexpensive, active, and stable nanostructured catalysts assuring both, the high activity and stability. Therefore, it is still important to develop Ni-based catalysts resistant to carbon deposition. Development of supported-bimetallic catalysts, containing nickel as a main component and a small amount of noble metal, can assure superior activity, selectivity to hydrogen and deactivation resistance than the corresponding monometallic catalysts.


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ORAL PRESENTATIONS

Catalyst Preparation, Characterization and Regeneration

Mechanical-chemical activation of Ni-Mo/γ-alumina catalysts for hydrodesulphurization

Stanislava Andonova, Chavdar Vladov, Ivan Mitov, Lychezar Petrov

Institute of Catalysis, Bulgaria Academy of Science, Sofia, Bulgaria

[email protected] The continuous deterioration of the quality of the extracted oil and the high environment requirements for reduction of the SOx emissions impose the development of more efficient catalysts for hydrodesulphurization (HDS). The application of a mechanical-chemical activation (MCA) is a comparatively new alternative for preparation of heterogeneous catalysts, which brings about the appearance of defects and/or destruction of the crystal lattice, variation in the form and in the size of the particles, changes in the specific surface area and in the porosity and the final result is highly active and disperse catalysts. The aim of present study is to carry out a detail research of the changes in the structure, phase composition and catalytic HDS activity of Ni(Co)-Mo/γ-Al2O3 catalysts after different periods of time of MCA, as well as to establish relationship between catalytic properties and the duration of the activation. The samples have been characterized by means of X -ray diffraction (XRD), X-ray photoelectron (XPS) and temperature-programmed reduction (TPR). The specific surface area has been determined by using BET method. As a model reaction for determination of the catalytic activity of the samples is used the reaction of thiophene HDS. The results showed that the MCA of the catalysts promotes their HDS activity and can reach maximum depending on the time of the treatment. It was established that the observed higher catalytic activity is related to the partial amorphization of the MoO3 crystallites which favor increasing the number of Mo6+ ions available for reduction. In addition the obtained results showed increased number of the catalytic active sites on the surface and enhanced degree of reduction and sulfidation of the mechano-chemical activated catalysts.


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Characterization of Nb2O5-ZrO2 mixed oxides synthesized from Nb(V) peroxo precursor as novel solid acids

Margarita Kantcheva, Olga Samarskaya, Hülya Budunoğlu, Ilknur Cayırtepe

Department of Chemistry, Bilkent University, 06800 Bilkent, Ankara, Turkey

[email protected]

Novel Nb2O5-ZrO2 solid acids were prepared by the so called “peroxo route” involving impregnation of amorphous ZrOx(OH)4-2x with acidic solutions of the peroxoniobium(V) complex, [Nb2(O2)3]4+. The precursor solutions were taken in concentrations ensuring ZrO2:Nb2O5 mole ratios ranging from 150:1 to 4:1. The structure of the calcined materials was characterized by XRD measurements, micro-Raman and DR-UV-vis spectroscopy. The surface acidity of the samples was investigated by in situ FT-IR spectroscopy using 2,6-dimethylpyridin (lutidine) as a probe molecule. The amount of Brønsted acid sites reaches maximum for the sample with ZrO2:Nb2O5 mole ratio of 6:1 corresponding to a pure phase of Zr6Nb2O17. This material does not possess Lewis acidity and has sufficient amount of Brønsted acid sites necessary for the stabilization of dispersed Pd(II) species. The potential of the Pd-promoted Zr6Nb2O17 as a catalyst for the reduction of NO with methane was evaluated by in situ FT-IR spectroscopic investigation of the reactivity of adsorbed NOx species toward the hydrocarbon.


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Catalysis Aspects of Carbon Nanofiber and Nanotube Production

Ahu Gümrah Dumanlı, Fatma Dinç, Ömer Faruk Mutaf, Taner Aytun, Yuda Yürüm

FENS, Sabancı University, Orhanlı Tuzla 34956, Istanbul-Turkey [email protected]

Catalytic Chemical Vapor Deposition (CCVD) is a good example of conversion of carbonaceous gases to crystalline graphitic carbon fibers or carbon nanotubes by using metal catalysts. The chemical and textural properties of the catalyst materials dictate the yield and quality of carbon nanofibers and CNTs/CNFs. The major aim of the present study was to elucidate the influence of the nature of the metal catalyst on the formation of carbon nanomaterial in the CVD process. We have chosen to evaluate the catalyst activity of the heterogeneous catalyst precursors due to the ease of varying the catalyst content using solution-based preparation. Additionally, the effect of the preparation of the catalyst using different starting materials and methods, on the carbon nanomaterial formation and structure especially from the thermodynamic, kinetic and electronic effect points of view by using CVD method was investigated. In order to prepare a selective and active catalyst for this study, transition metal-organic acid based catalyst precursors were synthesized. The structural, surface and chemical properties, thermal stability of the catalysts and carbon nanostructures have been investigated using XRD, SEM-EDS, FTIR, BET, solid state 13C-NMR and TGA methods.


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Preparation of Nanofiber Catalysts by Electrospinning

Özge Güvenir, Oğuz Bayraktar*

Petkim Petrochemicals Company, R&D Department, 35801 Aliağa, İzmir, Turkey *İzmir Institude of Technology, Chemical Engineering Department, İzmir, Turkey

[email protected] Use of nanofibers as catalyst is promising due to their high surface area, low resistance to flow of gases and liquids through a bundle of fibers and flexibility of form. Severe reaction conditions of some industrially important reactions limits the use of polymeric nanofibers in such catalytic applications. Therefore use of inorganic nanofibers for catalytic applications is promising. Inorganic nanofibers of silica, alumina, boria or metal oxides can be prepared by using electrospinning and sol gel techniques together and catalytically active metal can be doped on the nanofiber surface. Electrospunned and metal loaded fibers can be good candidates for many catalytic reactions In this study catalytic inorganic nanofibers that can resist high reaction temperatures will be prepared by using electrospinning and sol gel techniques together. Catalysts will first be characterized by using XRD, XRF, SEM, TEM, FTIR. Catalytic activity of fibers is planned to be tested on hydrogenation of benzene, one of the main products of Petkim, to cyclohexane, a new alternative product for Petkim.


15

Density Functional Modeling of CO Oxidation over unsupported Au

Tuğba Davran-Candan, A. Erhan Aksoylu, Ramazan Yıldırım

Chemical Engineering Department, Bogazici University, 34342 Istanbul, Turkey

[email protected]

Gold has received growing interest in the field of heterogeneous catalysis since it was realized that some gold catalysts prepared by co-precipitation method were extraordinarily active for the low temperature oxidation of CO. Today it is very well known that gold, when it is in the form of small clusters or finely dispersed on metal oxides, exhibits high catalytic activity and this activity is highly related to the ability of the clusters to adsorb CO and O2 simultaneously.

In this study, CO oxidation on an unsupported anionic gold cluster with six atoms (Au6-) was

investigated as the model catalyst using density functional theory (DFT) method. First, the optimum geometry of Au6

- was determined as a planar D3h structure. The adsorption and co-adsorption characteristics of CO and O2 were investigated thoroughly, next. Then, two plausible reaction pathways of CO oxidation, in which either CO or O2 was adsorbed on the apex site while the other was on the nearest lateral site, were analyzed based on the optimum co-adsorption structures obtained. In all calculations, Becke’s three-parameter hybrid functional (B3LYP) was used together with the Los Alamos National Laboratory second Double-Zeta (LANL2DZ) basis set and the corresponding Los Alamos relativistic effective core potential (RECP) for the heavy gold atom.

It was found that the reaction proceeded through a typical Langmuir-Hinshelwood mechanism taking

place in two steps for both initial structures. First, CO reacted with the molecular O2 leading to the first CO2 molecule and Au-O complex through the formation of a four centered intermediate structure (CO-OO). This was followed by the elimination of the remaining O on the cluster by another CO. The energy barrier for the formation of the intermediate and its decomposition into CO2 and Au-O complex was much lower when O2 was bonded to the apex site. The second step, on the other hand, was found to be identical for both initial structures. Keywords: CO oxidation, Au nanoparticles, DFT


16

Characterization and EIS analysis of 8YSZ nano particles prepared via reverse micelle

S. Vatansever, F. Öksüzömer, S. N. Koç, M. Somer*, H. Deligoz, M. A. Gürkaynak

Chemical Engineering Department, Istanbul University, 34320, Avcılar, İstanbul

* Chemistry Department, Koc University, 34450, Sarıyer, İstanbul [email protected]

In recent years numerous research projects are observed on decreasing the operating temperatures of solid oxide fuel cells (SOFCs) from high temperatures (1000oC) to intermediate temperature (800oC). Lower temperatures provide increasing of cell stability and allow the use of common materials for interconnection. This aim needs the development of new high-quality electrolyte materials. Zirconia is the most commonly used high performance ceramic material as an electrolyte. When doped with 8 mol % yittria, structure is stabilized and modified electrolyte shows high ionic conductivity as well as high thermal stability and excellent mechanical properties. [1–4] Nano-structured yttria stabilized zirconia particles were prepared by microemulsion system of n-octane/water/Triton X-100/hexylalcohol can act as nano-reactors which solubilize cationic solution and ammonia separately. ZrOCl2•8H2O and Y(NO3)3•6H2O used as inorganic precursors. The resulted powder calcinated at 800oC for 6 h and sintered at 1300, 1450, 1600 oC for 6 h. The resulting calcined and sintered particles are characterized by a scanning electron microscope (Joel JSM6335F) for morphology. The X-ray Diffractometer ( Rigaku D/Max-2200/PC ) is applied for the determination crystal phase and crystallite size of resulting particles after calcination. Ionic conductivity of resulting particles are measured by Solartron 1260 frequency responce analyser and Solartron 1296 Dielectric Interface. [1] Chih-Wei Kuo, Yueh-Hsun Lee, Ming Hung, Moo-Chin Wang, Shaw-Bing Wen, Kuan-Zong Fung, Chi-Jen Shin, Journal of Alloys and Compounds, In Press, Corrected Proof, Available online 22 January 2007. [2] Jiu-Peng Zhao, Mao-Hua Quan, Lei Zhang, Ceramics International accepted 25 May 2005 [3] Chih-Wei Kuo, Yueh-Hsun Lee, Moo-Chin Wang, Journal ofJournal of nan-Crystalline Solids 351 (2005) 304-311 [4] N.Petrova, D.Todorovsky, Materials Research Bulletin 41 (2006) 576-589


17

Semi-conductor Metal Oxide Thin Film Glazes For Ceramic Tiles And Glasses With Photocatalytic Self-cleaning Activity

Tuğçe İrfan Ersöz, Burcu (Koç) Haskılıç, Beril Korkmaz, Gürkan Karakaş

METU, Chemical Engineering Department, Ankara, Turkey

[email protected] Silica-titania mixed oxide thin films having different molar compositions of silica and titania were prepared by the sol-gel technique and dip coated on glass and ceramic substrates. These thin films were subjected to heat treatment at 400 oC and characterized by XRD, UV/Vis spectrophotometer and contact angle meter. From the XRD patterns of the films, titania nanoparticles in the deposited thin films are found to be in anatase phase and from UV/Vis spectrum, absorption edge energy of titania was found to be around 3.2 eV. The contact angle measurements revealed that coated surfaces have hydrophilic structure with contact angles as low as 12

degrees. Photocatalytic self-cleaning activity of the coated thin films was also examined with the degradation of the dried spots of red wine, methylene blue (25 mg/lt) and methyl orange (10 g/lt) dropped onto the coated surfaces under 300 W/m2 artificial solar irradiation for 24 hours.


18

Synthesis and Characterization of micro-mesoporous Mixed-PILCs with varying

pillar density

Nurgün Beşün, İlyas Deveci, Lütfi Erden, Hanife Erden

Muğla University, Department of Chemistry, 48000 Muğla, TURKEY [email protected]; [email protected]

Pillaring of clay with inorganic polycation to prepare thermally stable rigid cross linked materials of uniform micropores and acidity provide wide opportunities to be used as solid acid catalyst. The interaction of the second and/or third cationic components with the pillars in the microenvironment of the clay is very crucial for the property of the solid, and it has been shown that pillared clay with different basal spacing and microporosity were prepared with mixed cation pillaring. The micro-mesoporous nature and acidic property of the clay materials can also be varied by alternating the pillar density or in other words the lateral spacing between the pillars. Preparation, characterization and acidity properties of mixed-pillared clays with different pillar density, starting from Ni2+ exchanged clay are described. The structural and textural characteristics have been evaluated using X-ray diffraction (XRD), Fourier Transform Infra-red (FT-IR) spectroscopy and sorptometric studies. The decrease in the cation exchange capacity (CEC) of the Ni2+ exchanged clay depends upon the pretreatment temperature. It has been found that these single and multioxide PILCs with varying pillar density can be suitable as solid acid catalyst.


19

Environmental Catalysis

NO2 and Dimethyl Ether (DME) Reaction on Al2O3 as a Catalyst

Emrah Özensoy, D. Herling*, Janos Szanyi**

Department of Chemistry and Institute of Material Science and Nanotechnology, Bilkent University, Ankara 06460, Turkey

* Materials Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA ** Institute for Interfacial Catalysis, Pacific Northwest National Laboratory, Richland, WA 99352,

USA [email protected]

Dimethylether (CH3OCH3, DME) is a widely utilized commodity chemical which is also projected to be one of the fundamental chemical feedstocks in the future. Recently, application of DME as a reducing agent in selective catalytic reduction of NOx in diesel powered engines has also been suggested. Thus in this study, NO2 and dimethylether (DME) adsorption as well as DME and NO2 coadsorption on a transition metal-free γ-alumina catalyst were investigated via in-situ transmission Fourier transform infrared spectroscopy (in-situ FTIR), residual gas analysis (RGA) and temperature programmed desorption (TPD) techniques. NO2 adsorption at room temperature leads to the formation of surface nitrates and nitrites. DME adsorption on the alumina surface at 300 K leads to molecularly adsorbed DME, molecularly adsorbed methanol and surface methoxides. Upon heating the DME-exposed alumina to 500-600 K the surface is dominated by methoxide groups. At higher temperatures methoxide groups are converted into formates. At T > 510 K formate decomposition takes place to form H2O(g) and CO(g). DME and NO2 coadsorption at 423 K do not indicate a significant reaction between DME and NO2. However, in similar experiments at 573 K, fast reaction occurs and the methoxides present at 573 K before the NO2 adsorption are converted into formates, simultaneously with the formation of isocyanates. Under these conditions, NCO can further be hydrolyzed into isocyanic acid or ammonia with the help of water which is generated during the formate formation, decomposition and/or NCO formation steps.


20

Structural Characterization and Activity for Ethanol Electro-oxidation of Carbon Supported Pt–Sn Bimetallic Catalysts Prepared by Polyol Method

Hilal Kıvrak, Sadig Kuliyev*, Deniz Üner

Chemical Engineering Department, Middle East Technical University, Ankara, 06531 Turkey

* Vestel Defence Industry, Ankara, 06450, Turkey [email protected]

In this study XRD, microcalorimetric measurements of carbon monoxide and hydrogen, and cyclic voltametric oxidation of ethanol on 20%Pt-Sn/C catalysts were performed to investigate how Sn addition affects electronic and geometric structure of catalysts and how the mechanism of ethanol electro-oxidation changes in the presence of Sn. Sn promoted carbon supported Pt catalysts were prepared by polyol method by dissolving H2PtCl6.6H2O, SnCl2.2H2O, and XC72-R in ethylene glycol reduction method under Ar atmosphere by changing Pt:Sn atomic ratios 1:0 to 15:1. Differential heats of carbon monoxide, hydrogen adsorption were measured at 323 K by using a Tian-Calvet type heat flow calorimeter (Seteram C-80) and electrochemical measurements on these catalysts were performed in a conventional three-electrode cell at room temperature using of Iviumstat potentiostat. Differential heats of CO and H2 adsorption data was used to determine the population and the strength of the defect-like sites present in the catalysts. Ethanol electro-oxidation was performed in 0.5 M H2SO4 in different concentrations of C2H5OH on Pt-Sn/C, Pt/C, and Pt/C (E-tek) catalysts. Cyclic voltammetry results on Pt/C catalysts revealed that by increasing concentration of ethanol increases the current values in 0.25M -1M concentration range. Present results indicated that per gram of Pt activity for a commercial 20% Pt/C (E-Tek) catalyst and homemade Pt/C catalyst were approximately same. Work is in progress, to compare the performances of Pt-Sn bimetallic catalysts and the role of the defect-like sites in electro-oxidation of ethanol.


21

Microwave assisted preparation of Pt based catalysts for PEMFCs

Ayşe Bayrakçeken, Lemi Türker*, İnci Eroğlu

METU, Department of Chemical Engineering, Ankara, Turkey. * METU, Department of Chemistry, Ankara, Turkey.

[email protected]

One of the most important parameters that affects the performance of proton exchange membrane fuel cells (PEMFCs) is the catalytic activity of the Pt/C catalysts. The higher the contact between the Pt metal and the electrolyte the better the Pt utilization obtained. It is essential to obtain high catalytic activities, small particle sizes and high dispersion of the Pt on the carbon support. Impregnation is a very commonly used method but in this method it is not easy to control the shape and particle size of the Pt metal. Recent studies showed that microwave irradiation method seems to be an efficient way to prepare catalysts. Compared to the conventional heating mediums, microwave irradiation is not only time efficient but also provide small and well dispersed metal particles onto the support. In this study, by using microwave irradiation, platinum has been decorated onto the carbon supports. The effects of different parameters such as base concentration, different carbon supports, and microwave duration on the particle formation were investigated. The prepared catalysts were characterized by XRD, XPS and it was observed that by using this method, very small particles in the order of 2-6 nm can be obtained. The PEMFC tests of the prepared catalysts showed that the preparation conditions which influence the particle size of the catalysts have a significant effect on the performance of the PEMFCs.


22

Influence of ion-exchange resin catalysts on the reaction of the esterification of iso-butanol with propionic acid

Alime İzci, Halit Levent Hoşgün

Eskişehir Osmangazi University, Chemical Engineering Department, Eskisehir, Turkey

[email protected]

Esters can be formed by the reaction of a carboxylic acid with an alcohol forming the ester and water molecules. This esterification (reversible) reaction is a very important and a common type of reaction in the chemical engineering industry. Conversions for esterification reactions have long been known to be limited by a slow reaction rate and the existence of reversible reactions. To accelerate the reaction rate, catalysts are always employed in a liquid-phase esterification. Polystyrene sulfonic acid resins are the most commonly used solid acid catalysts in organic reactions. In this work, kinetics of reaction of the formation of iso-butyl acetate in the heterogeneously catalyzed esterification of iso-butanol with propionic acid were studied in a stirred batch reactor at temperatures between 45 and 75 °C. Two polystyrene-co-divinylbenzene sulfonic acid resins from Rohm and Haas (Amberlyst 70 and Amberlyst 36) have been studied in terms of their acidities. To have a purely kinetic study, the effects of external diffusion limitation and internal diffusion, and also catalyst loading on the esterification reaction rate were studied. To study the external diffusion effect and the internal diffusion effect, different stirrer speeds and particle sizes were applied to the reaction system, respectively. It was found that both external and internal diffusion limitations did not affect the overall reaction rate. The conversion of propionic acid increased with increasing temperature and catalyst loading. Kinetic model was tested to correlate the kinetic data, the pseudo-homogeneous (P-H) model. In this model, the activity coefficient was estimated.


23

EFFECT OF HEAT TREATMENT ON THE ACTIVITY OF HETEROPOLY ACID CATALYSTS IN ETBE SYNTHESIS

Levent Değirmenci, Nuray Oktar, Gülşen Doğu

Chemical Engineering Department, Gazi University, 06570, Maltepe, Ankara, Turkey

[email protected] Oxygenates which improve the burning characteristics of gasoline has long been used as octane enhanchers in gasoline reformulation. Among the oxygenates ethyl tertiary butyl ether (ETBE) production had gained an increasing attention with its advantages over methyl tertiary butyl ether (MTBE) such as lower water solubility, lower Reid vapor pressure (RVP) and higher octane number [1]. Heteropoly acid catalysts employed in etherification reactions were known to have high activity especially in vapor phase production [2]. In this presentation, effect of heat treatment on the activity of heteropoly acid catalysts, namely tungstophosphoric acids (TPA) and silicotungstic acid (STA) was investigated by conducting reaction experiments in vapor phase followed by characterization studies. Vapor phase ETBE production catalyzed by heteropoly acids was performed in the temperature range of 353-523 K. Reaction experiments and FTIR analyses were conducted with heteropoly acid catalysts which were treated at temperatures corresponding to the structural changes observed from TGA/DTA analysis. It was observed that the activity change of STA treated at 573 K and tungstophosphoric acid Keggin (TPA-K) treated at 473 K were insignificant as compared to untreated catalysts for vapor phase ETBE production. ETBE conversion was not observed with TPA-K treated at 573 K due to the removal of protons in the structure at that temperature. Results of reaction experiments supported by FTIR analyses showed that the stability of STA was higher than TPA-K. REFERENCES [1] Ancillotti, F., Fattore, V., Oxygenate fuels: market expansion and catalytic aspect of synthesis, Fuel Processing Technology, 57, 163-194, 1998. [2] Pozniczek, J., Micek-Ilnicka, A., Lubaska, A., Bielanski, A., Catalystic synthesis of ethyl-tert butyl ether on Dawson type heteropolyacid, Applied Catalysis A: General, 286, 52-60, 2005.


24

KINETICS OF LOW TEMPERATURE CO OXIDATION OVER ACTIVATED

CARBON SUPPORTED Pt-SnOx CATALYSTS

Seda Acun, Şeyma Özkara-Aydınoğlu, A. Erhan Aksoylu, Z. İlsen Önsan

Department of Chemical Engineering, Boğaziçi University, Bebek 34342 Istanbul, Turkey [email protected]

An experimental kinetic study of low-temperature CO oxidation was conducted in the absence and presence of hydrogen over air-oxidized activated carbon supported 1wt%Pt-0.25wt%SnOx prepared by sequential impregnation. Kinetic experiments were conducted at 383 K and atmospheric pressure using different sets of CO and O2 concentrations, each at different space times and catalyst loadings. Molar reactant concentrations in the feed were varied between 1-10 per cent CO and 1-4 per cent O2 in the absence of H2. The effect of the presence of H2 in the feed on CO oxidation rates was also investigated under similar conditions, and in preferential CO oxidation experiments, H2 concentrations used were varied between 10 and 45 per cent. Experimental rate data were used to estimate kinetic parameters of the power law model by using the method of initial rates. Power law kinetics gave reaction orders of 0.87 and 0.13 with respect to carbon monoxide and oxygen, respectively, and a reaction rate constant of 1.37 µmol.mg-1.min-1.atm-1 at 383 K. The agreement between experimentally measured and model predicted rates was good, and the variance of experimental error was calculated as 0.017 (µmol.g-1.s-1)2. Finally, the addition of H2 into the feed did not alter reaction kinetics, but an almost four fold enhancement effect was observed in CO oxidation rates over 1wt.%Pt-0.25wt.%SnOx/AC2 at all the feed H2 concentrations tested.


25

Investigation of the Microwave Effect on Catalyst Synthesize for PEM Fuel Cells

Evren Oğur, Furkan Dundar*, Aylin Aytac**, Ali Ata*

Gebze Institute of Technology, Chemical Engineering Dept., 41400 Gebze, Kocaeli, Turkey

* Gebze Institute of Technology, Materials Science and Engineering Dept., 41400 Gebze, Kocaeli, Turkey ** Gebze Institute of Technology, Energy Systems and Engineering Dept., 41400 Gebze, Kocaeli, Turkey

[email protected]

Fuel cells are becoming the world’s next step for cleaner and efficient energy conversion. Their high energy and power density keep them as an alternative energy converter for the market. Within the construction of the infrastructure and the education of people, they will be more popular, soon. PEM fuel cells are the most established fuel cell technology up to now. The most important reason, keeping PEM fuel cells far from commercializing is, the cost of the fuel cell. In order to reduce the cost of the fuel cell scientists try to find better ways to improve the usage of the precious material used in the catalyst layer. Utilization of the precious material is the key factor for decreasing the amount of catalyst loading in the fuel cell which is directly related to the cost of the fuel cell. The dispersion of the precious metal catalyst over the support material and placing them to accessible regions is the aim of outstanding catalyst synthesize. Microwaves have significant effects on catalyst synthesize procedure, such as providing good dispersion of the catalyst, decreased reduction duration and improved thermal stability against agglomeration. In this study microwave integrated polyol process for PEM fuel cell catalysts synthesize is shown. Cyclic voltametry experiments are used for active surface area measurements and BET methode is used for reel surface area measurements. TEM investigation is used for particle size analysis and determination of homogenous distribution of the precious catalyst material. The effect of microwave integration in the synthesize procedure is shown with the analytical methods discussed above.


26

Oil, Gas and Petrochemicals The Effect of Ce Loading and Impregnation Strategy on Methane Dry Reforming

Activity of Ce promoted Pt/ZrO2

Şeyma Özkara-Aydınoğlu, Emrah Özensoy*, A. Erhan Aksoylu

Department of Chemical Engineering, Boğaziçi University, Bebek 34342 Istanbul, Turkey * Department of Chemistry and Institute of Material Science and Nanotechnology, Bilkent

University, Ankara 06460, Turkey [email protected]

Dry reforming of methane has been studied over Pt/ZrO2 catalysts promoted with Ce at different temperatures and feed compositions. The influence of the impregnation strategy and the cerium amount on the activity and stability of the catalysts were investigated. The extent of interaction between metal components during preparation procedures was investigated through determination the amounts of metallic phases of Pt and Ce by X-ray photoelectron spectroscopy (XPS). The results have shown that introduction of 1 wt.% Ce to the Pt/ZrO2 catalyst via coimpregnation method led to the highest catalytic activity and stability. The catalyst also displayed a significant improvement in the H2/CO production ratio, i.e. H2/CO ratio tends to unity at high temperatures. Increasing the loading of Ce from 1wt.% to 5 wt.% resulted in a decrease in catalytic activity of catalysts. 1wt.%Ce-1wt.%Pt/ZrO2 catalyst prepared by sequential impregnation displayed inferior CH4 and CO2 performances with lowest H2/CO production ratios over the whole temperature range and time-on-stream. 1wt.%Ce-1wt.%Pt/ZrO2 catalyst prepared by coimpregnation showed the highest activity even for the feed with high CH4/CO2 ratio. The reason for the high activity was explained by the intensive interaction between Pt and Ce phases for coimpregnated sample, which had been verified by XPS analysis.


27

METHANOL DEHYDRATION REACTION TO PRODUCE CLEAN DIESEL

ALTERNATIVE DIMETHYLETHER

Dilek Varışlı, Kenan Cem Tokay, Ayşegül Çiftçi, Timur Doğu, Gülşen Doğu

METU, Department of Chemical Engineering, Ankara, Turkey * Chemical Engineering Department, Gazi University, 06570, Maltepe, Ankara, Turkey

[email protected] Considering the potential oil shortage problems forseen in the coming decades, synthesis of alternative transportation fuels has become an expanding research area. Among different alternatives, alcohol based fuels has attracted major attention of researchers and fuel producers [1-2]. Dimethylether (DME), which can be produced by dehydration of methanol, is a clean burning diesel fuel alternate. Due to its high cetane number (55-60) and high oxygen content, it has good burning characteristics and it produces low NOx and soot emissions [3]. Catalysts having acidic characteristics are suitable for dehydration of alcohols. Besides DME, formaldehyde is produced as the main side product during methanol dehydration. A mesoporous aluminum silicate catalyst with a surface area over 900 m2/g and with an Al to Si atomic ratio of 0.03 showed good activity over 250oC. A DME yield of about 0.65 was obtained over 400oC at a space time of 0.27 s.g. cm-3. New catalysts having different Al/Si ratios and different HPA/SiO2 ratios were synthesized and tested in methanol dehydration. In this presentation a review of our recent studies on methanol dehydration reaction over different solid acid catalysts, such as mesoporous aluminum silicate type catalysts, heteropolyacid catalysts (HPA) [4] and supported nanocomposite HPA-Silicate acidic catalysts will be reported. Acknowledgement: Financial support of TUBITAK through project 106M073 and DPT BAP0304DPT2003(06K12092017) are gratefully acknowledged. References 1. Doğu, T., Varışlı, D. Alcohols as Alternates to Petroleum for Environmentally Clean Fuels and Petrochemicals. Turkish Journal of Chemistry, 31,551-567 (2007). 2. Olah, G.A., Goeppert, A. Prakash, G.K.S. Beyond Oil and Gas: The Methanol Economy. Wiley-VCH, LA USA, 2006. 3. Ogawa, T., Inoue, N., Shikada, T., Ohno, Y., Direct Dimethyl Ether Synthesis. Journal of Natural Gas Chemistry 12, 219-227 (2003). 4. Varisli, D., Dogu, T., Dogu, G., “Ethylene and diethyl-ether production by dehydration reaction of ethanol over different heteropolyacid catalysts”, Chem. Eng. Sci., 62, 5349-5352 (2007).


28

CATALYTIC COMBUSTION OF METHANE AND HYDROGEN OVER PRECIOUS METAL MONOLITH TYPE CATALYST

Alper Sarıoğlan, Özgür Can Korkmaz, Aslı Kaytaz, Atilla Ersöz, Fehmi Akgün

TÜBİTAK MAM Energy Institute P.O.21, Gebze/KOCAELI – TURKEY

[email protected]

An experimental study on catalytic combustion of natural gas and hydrogen mixtures on commercial monolith catalysts has been carried out and the effect of gas hour space velocity (GHSV, h-1), percentage of methane and hydrogen and oxygen to carbon ratio has been investigated. In the studies, nitrogen oxides (NOx) and carbon monoxide emissions formed upon the operating conditions have been measured and interpreted accordingly. The kinetic of the catalytic combustion of natural gas has also been studied. Methane reaction rates have been measured upon the progress of the reaction temperature and activation energy and preexponential factor of the reaction have been determined. Catalytic combustion of natural gas and hydrogen start at about 200°C and at ambient temperature, respectively. Above 5 percent of methane, both catalytic and homogeneous combustion occur. The rate of combustion varies with the temperature. At low temperatures, the rate of the reaction is determined by the rate of the catalytic reaction. At higher temperatures the transport to the catalytically active surface cannot keep up with the catalytic reaction. As a result the rate of the reaction is determined by the transport to the catalytically active surface. The homogeneous gas phase combustion sets on at about 700 °C. The Arrhenius Lnk-1/T plot shows refraction. The observed refraction is believed to come from the change in the reaction mechanism. As a plausible explanation, the transition from the reaction mechanism in which oxygen adsorption is predominant to one in which methane adsorption is most important occurs with increasing reaction temperatures.


29

PARTIAL REGENERATION OF NI-BASED CATALYSTS FOR HYDROGEN

PRODUCTION VIA METHANE CRACKING: MODELING AND OPTIMIZATION

Reyyan Koç, Erdoğan Alper, Eric Croiset*, Ali Elkamel*

Chemical Engineering Department, Hacettepe University, Beytepe, Ankara, Turkey

* Chemical Engineering Department, University of Waterloo, Waterloo, Ontario, Canada [email protected]

High purity, carbon monoxide-free hydrogen and filamentous carbon can be produced by thermo catalytic cracking of methane. Carbon filaments continue to grow until the catalyst deactivates because of carbon encapsulation. Regeneration of catalyst is getting importance to maintain a continuous process. Our work on optimization of the partial regeneration method showed that activity of the catalyst can be sustained for longer times by gasifying not all but some extent of the deposited carbon. A kinetic model which consists of surface reactions, filament formation and deactivation was developed for the regenerated catalyst. It is assumed that reaction parameters at the molecular level do not change when the burn off degree is at a moderate extent but these parameters changed drastically when burn off degree is vastly increased or decreased. Rate constant for the encapsulation reaction is adjusted for the simulation results to be representative of the experimental results (typically specific weight of carbon (g C/g Ni) vs. time on stream). The system of differential algebraic equations consists of the steady-state equations for all surface intermediates, an algebraic equation of dissolution/segregation, diffusion equation and the site balance equation. The system has been solved without assuming any rate-determining step or most abundant surface intermediates. Parameter estimation procedures were repeated for the deactivation cycles of regenerated 5 wt% Ni/g-Al2O3 catalyst. The basic idea lies under the model was that every carbon atom will diffuse through the nickel particle and participate in the formation of carbon filaments until the catalyst deactivates. Specific weight of carbon is calculated by using the rate of carbon diffusion. Although the model provides a close estimation for the determination of weight gain during the thermo catalytic cracking of methane, model fails at the initial stage of carbon deposition and gives higher rates of carbon deposition than the experimental results.


30

Development of active and selective catalysts for oxidative dehydrogenation of propane

Hilal Aykaç, Selahattin Yılmaz*

Petkim Petrochemicals Company, R&D Department, 35801 Aliağa, İzmir, Turkey * İzmir Institute of Technology, Chemical Engineering Department, İzmir,Turkey

[email protected]

Ethylene is the preferred product in steam cracking process but the demand for propylene is growing faster than that for ethylene. In the case of FCC, propylene yield is lower than that of ethylene. This situation has raised new interest in producing light alkenes from alkanes, which are generally easily available and used as low-cost feedstock for chemical production. Even though catalytic dehydrogenation of propane is more selective to propylene than established processes, in dehydrogenation processes the thermodynamic constraints are limiting the alkane conversion. Strong endothermic reaction, necessity to supply heat at high temperature, side reactions, and coking and rapid catalyst deactivation problems are experienced. These limitations have raised new interest to develop a potentially important catalytic process, oxidative dehydrogenation (ODH) of propane for producing propylene. In the case of ODH, reaction becomes exothermic and is able to proceed at much lower temperatures. This fact reduces the side reactions, such as cracking of alkanes and coke formation, as well as overcomes the thermodynamic limitations. The aim of this project is to develop more active and selective catalysts than those of used in commercial production in propane non-oxidative dehydrogenation. Catalysts will be characterized in terms of acidity, surface properties and metal support interactions.


31

POSTER PRESENTATIONS P1

PRODUCTION OF ETHYL ACETATE USING HETERO-POLY ACID INCORPORATED MCM-41 TYPE CATALYSTS

Yeşim Güçbilmez, Selime Varlı, Sibel Aslan, Halit L. Hoşgün*

Anadolu University, Department of Chemical Engineering, Eskişehir, Turkey

* Eskişehir Osmangazi University, Department of Chemical Engineering, Eskişehir, Turkey [email protected]

Ethyl acetate is an important raw material for many applications in chemical industry including coatings, adhesives, perfumes, and plasticizers [1]. One of the most common production methods of ethyl acetate is the direct liquid phase esterification of acetic acid with ethanol where the reactants are contacted in the presence of acids such as sulfuric acid and p-toluene sulfonic acid (PTSA) or solid acids such as ion exchange resins and H-ZSM-5 [2,3]. Solid acid catalysts are preferred over acid catalysts since the latter is toxic, corrosive and difficult to remove from the end-product [4]. MCM-41 type catalysts are promising supports because of their significantly high surface areas (>1000 m2 g−1), high thermal stabilities (ca. 900 C) and large pore sizes (1.5–8 nm) [5]. Hence, a hetero-poly acid such as tungsto-phosphoric acid (HPW) may be incorporated into the MCM-41 structure and a solid acid catalyst with high surface area and large pores, which in turn decreases the diffusion limitations, can be obtained. In literature, HPW-MCM-41 catalysts have been synthesized characterized and tested for several esterification reactions [6-8]. In this study, a previously synthesized MCM-41 catalyst (with a BET surface area of 1055 m2/g) will be used as a support in order to immobilize HPW. The resulting catalyst will be used in the esterification reaction of ethanol with acetic acid to produce ethyl acetate in a 150 mL glass reactor equipped with reflux condenser and the reaction mixture will be mixed using a magnetic stirrer. The same catalyst can also be used as a potential catalyst for the production of ethyl lactate, a green solvent, by the esterification of lactic acid with ethanol in the liquid phase. References [1] Kuo-Ching Wu and Yu-Wen Chen, Appl. Catal. A: Gen., 2004, 10, 33-42 [2] Wen-Tzong Liu and Chung-Sung Tan, Ind. Eng. Chem. Res., 2001, 40, 3281 -3286 [3] S. Dassy, H. Wiame and F.C. Thyrion, J. Chem. Tech. Biotechnol., 1994, 59, 149 [4] J.C. Juan, J. Zhang and M. A. Yarmo, J. Mol. Catal. A: Chem., 2007, 267, 265-271 [5] C.T. Kresge, M.E. Leonowicz, W.J. Roth, J.C. Vartuli and J.S. Beck, Nature, 1992, 359, 710 [6] I.V. Kozhevnikov, Chem. Rev., 1998, 98, 171-198 [7] M.J. Verhoef, P.J. Kooyman, J.A. Peters and H. Van Bekkum, Micropor. Mesopor. Mater.,1999, 27, 365-371. [8] L.R. Pizzio, P.G. Vazquez, C.V. Caceres and M.N. Blanco, App. Catal. A: Gen., 2003, 256, 125-139


32

P2

CATALYTIC DEGRADATION OF POLYPROPYLENE WITH SBA-TYPE CATALYSTS

Zeynep Obalı, Naime Aslı Sezgi, Timur Doğu

Middle East Technical University, Department of Chemical Engineering, Ankara, Turkey

[email protected] The amount of waste plastics generated by our society has been growing rapidly. The low biodegradability of these wastes creates serious environmental problems that forces governments to propose a permanent solution to solve the waste plastics problem by landfilling or incineration. Production of toxic gases and limitations in availability of suitable and safe depots are some of the disadvantages of the two methods. Because of this, production of new products by degrading the waste plastics gained importance. Major advantages of the catalytic thermal degradation over the non-catalytic process are lower operating temperatures, higher conversions to valuable chemicals and higher degradation speeds. Porous materials with a wide range of pore size distribution are offering a variety of challenges to the research community and industry. Microporous materials have one important drawback that limits their application; reactions with bulky molecules can not be handled due to pore size limitations. To overcome this situation, a continuous research was done to develop materials with constantly larger pores. Finally these researches led to the development of mesoporous materials (MCM-41, SBA-15, etc.) mainly made up of SiO2 and having high surface area and narrow pore size distribution. To increase their catalytic activity in polymer degradation reactions, aluminum is incorporated into the silica framework. In this study, pure and aluminum containing SBA-type catalysts were synthesized by using hydrothermal synthesis route [1,2] in order to be tested in catalytic degradation of polypropylene. Tetraethyl orthosilicate and aluminum isopropoxide were used as the Si and Al sources, respectively. It was observed that these materials had high surface area in the range of 600-850 m2/g and exhibited isotherms of type IV. From XRD analysis, the structure of synthesized materials was considered as SBA-15. The activities of some of these catalysts in the degradation reaction of polypropylene were investigated by thermogravimetric analyses (TGA).The TGA results showed a marked reduction in the degradation temperature in the presence of aluminum containing SBA-type catalyst. This catalyst caused a significant decrease in the activation energy of the reaction from 172 kJ/mol to a value of 73.0 kJ/mol. References [1] Fulvio, P.F., Pikus, S., Jaroniec, M., J.Coll.Inter.Sci, 287 (2005) 717-720. [2] Kumaran, G.M., Garg, S., Soni, K., Kumar, M., Sharma, L.D., Dhar, G.M., Rao, K.S.R., Appl.Catal.A:General, 305 (2006) 123-129.


33

P3

Mesocellulous Silica Foam (MCF) Supported V-Ce Mixed Metal Oxide for Selective Oxidation Reactions

Özge Aktaş, Sena Yasyerli, Gülşen Doğu, Timur Doğu*


* Middle East Technical University, Department of Chemical Engineering, Ankara, Turkey [email protected]

Mesocellulous silica foam (MCF) has a recently reported mesoporous material composed of large uniform spherical cells (up to 50 nm) interconnected by uniformly sized windows with a narrow pore size distribution. In the present study, V-Ce mixed oxide incorporated MCF type mesoporous catalytic materials were synthesized by the impregnation and the one-pot synthesis procedures for selective oxidation reactions. Pure siliceous MCF material was prepared according to hydrothermal synthesis, using Pluronic P123 triblock copolymer surfactant with 1.3.5-trimethylbenzene (TMB) as the organic swelling agent with TMB/P123=0.5 (wt/wt) and TEOS as the silica source. V-Ce@MCF catalyst was prepared by the impregnation of equal amount of cerium and vanadium into synthesized MCF material. In the case of one pot synthesis of V-Ce-MCF, a solution of metal salts was added to the mixture of surfactant and water before the hydrothermal synthesis step. The XRD patterns of pure MCF material showed three peaks at very low angles (2θ range from 0.2o to 1o), which characterized hexagonal MCF symmetry. The XRD pattern of V-Ce-MCF prepared by one-pot procedure was similar to XRD pattern of pure MCF, while a small shift to right in the XRD pattern of V-Ce@MCF was observed. There are no peaks corresponding to vanadium and cerium in the XRD patterns of V and Ce incorporated MCF. Pure MCF had a surface area of 932 m2/g. After impregnation of V and Ce (2.5 % wt each) into MCF structure, a significant decrease in the surface area (574 m2/g) was observed. However, addition of V and Ce (2.5 % wt each) into MCF material by one-pot procedure did not change the surface area of the V-Ce-MCF catalyst (967 m2/g). Acknowledgment: Gazi University Research Fund is gratefully acknowledged.


34

P4

DRY REFORMING OF METHANE OVER Pd-Ni-MCM-41 DUAL CATALYSTS

Canan (Şener) MARTI, Katia ARISHTIROVA*, R.N. NIKOLOV*, Timur DOĞU, Gülşen

DOĞU**, Sonia DAMYANOVA*

Middle East Technical University, Department of Chemical Engineering, Ankara, Turkey * Institute of Catalysis, Bulgarian Academy of Science, Sofia, Bulgaria

** Chemical Engineering Department, Gazi University, 06570, Maltepe, Ankara, Turkey [email protected]

Due to increased significance of hydrogen as a clean burning energy source, research efforts have been focused on improving hydrogen production technologies in recent decades. One of the most attractive methods of producing synthesis gas is dry reforming of methane using CO2. In this study, it was aimed to develop effective Pd-Ni-MCM-41 bimetallic catalysts supported on MCM-41 mesoporous silica, which provided high stability and activity in dry reforming reaction of methane for producing hydrogen. MCM-41 support material was synthesized by hydrothermal synthesis technique. Nickel and palladium was incorporated into the MCM-41 structure by successive impregnation. Catalysts containing Ni/Si weight ratios of 0.2, 0.3, 0.4 and 0.6% (wt) Pd were characterized by EDS, XRD, N2 physisorption, XPS, SEM, TEM and H2 TPR techniques. XRD patterns of the samples indicated that the characteristic MCM-41 structure was preserved after impregnation of the metals. TEM images indicated that Ni and Pd nanoballs were well dispersed inside the MCM-41 structure. The catalysts also have high surface area values (400-600 m2/g) and narrow pore size distributions in the mesoporous range (2-3 nm). Pd-Ni-MCM-41 catalysts showed high CH4 and CO2 conversions, as well as high H2/CO ratios and quite high stability. The Pd-Ni catalyst with Ni/Si ratio of 0.30 exhibited the best catalytic properties. The promotional effect of Pd on catalytic activity and stability of the bimetallic catalysts was attributed to the easy reduction of nano-sized nickel oxide species and better dispersion of nickel metal particles. Acknowledgements. The financial support of the project between TUBITAK and Bulgarian Academy of Sciences, project No.105M373 & project No. X-1515/05 from National Science Fund at Bulgarian Ministry of Education and Science and project No. 106M073 from TUBITAK are gratefully acknowledged.


35

P5 Mesoporous Cu-Zn-Al Incorporated Mesoporous Catalysts for Direct Synthesis

of Dimethylether from Synthesis Gas

Ayça ARINAN, Dilek VARIŞLI, Zeynep OBALI, Timur DOĞU

Middle East Technical University, Department of Chemical Engineering, Ankara, Turkey [email protected]

Dimethylether (DME) is new transportation fuel alternate which can be directly synthesized from synthesis gas. Its properties are similar to LPG and also it has comparable properties with diesel fuel. Conventionally it is produced by dehydration of methanol. However, nowadays numbers of researchers have been attracted to synthesize DME in a single step directly from a H2 – CO gas mixture which can be obtained by gasification and/or reforming of fossil fuels [1]. For the direct synthesis of DME from synthesis gas, development of hybrid catalysts with two kinds of active sites, one is being for methanol conversion and the other for the dehydration reaction, are needed [2]. In this study, silicate structured mesoporous catalysts incorporated with Al2O3, ZnO and CuO were synthesized for the direct synthesis of DME. Catalysts were prepared by the impregnation of Zn and Cu into mesoporous aluminosilicates containing different Al/Si ratios and also by the direct hydrothermal synthesis procedure using salts of Cu, Zn, Al and Si together with a surfactant (cetyl-trimethylammonium bromide) Catalysts with different weight ratios of CuO/ZnO/Al2O3 were successfully synthesized and the characterization of these materials by XRD, N2 adsorption techniques indicated the formation of MCM-41 like mesoporous structures with narrow pore size distributions and surface area values over 800 m2/g. Effect of pH of the synthesis procedure on the incorporation of active oxides into the catalyst structure was illustrated. Surface acidity, which is very important for the dehydration reaction step, was measured through DRIFTS analysis of pyridine adsorption. References 1.T. Ogawa, N. Inoue, T. Shikada, Y. Ohno, Direct Dimethyl Ether Synthesis, 219-227 (2003) 2.G. R. Moradi, S. Nosrati, F. Yaripor, Effects of the Hybrid Catalysts Preparation method Upon Direct Synthesis of Dimethyl Ether from Synthesis Gas, 598-606 (2007)


36

P6

Partial Oxidation of Benzene to Phenol with Nitrous Oxide on Fe- and Co-ZSM-5: A Density Functional Study



[email protected]

The direct oxidation of benzene to phenol is an attractive alternative to the traditional cumene process, which coproduces acetone as a by-product. Several studies have shown that nearly 100% selectivity to phenol can be achieved by oxidizing benzene with N2O over ZSM-5 containing extra-framework iron. Several quantum chemical studies have been reported aimed at further defining the possible structure of the iron–oxo site. The purpose of this study is to determine and compare the relative energy profiles of partial oxidation of benzene to phenol with nitrous oxide by using density functional theory on clusters representing Co-ZSM-5 and Fe-ZSM-5 catalysts. Fe-ZSM-5 and Co-ZSM-5 zeolite surfaces were modeled as Si4AlO4H12Fe(Co) clusters. All of the cluster atoms, reactant and product molecules were kept relaxed. The dangling orbitals of the peripherial Si atoms were saturated with H atoms. Energy profiles were studied by means of DFT calculations as implemented in Gaussian’03 program at B3LYP level using 6-31G** as basis set for all of the atoms. Relative reaction energies of direct oxidation of benzene to phenol were determined for Si4AlO4H12Fe(Co) clusters. The first reaction step is N2O decomposition on Fe- and Co-ZSM-5. The second step is benzene adsorption on FeO- and CoO-ZSM-5 clusters. These reactions occur with activation barrier values of 20.1 kcal/mol and 21 kcal/mol and with reaction energy values of -20.8 kcal/mol and -13.9 kcal/mol on FeO- and CoO-ZSM-5 clusters, respectively. A further reaction step is the formation of phenol on clusters. The last step is desorption of phenol from the surface.


37

P7

ETHERIFICATION OF GLYCEROL BY TERT-BUTYL ALCOHOL CATALYSED BY ION EXCHANGE RESIN

Nalan Özbay, Nuray Oktar, Gülşen Doğu, Timur Doğu*



Glycerol, which forms as a major by-product of biodiesel production by transesterification of vegetable oils with methanol [1], cannot be added directly to fuel because of its decomposition, polymerization and consequential engine problems at high temparatures. Oxygenated molecules are valuable fuel additives for their good burning properties, causing decreased exhaust emissions of particulate matter, hydrocarbons, CO and unregulated aldehydes [2-3]. In the present study, the etherification reaction of glycerol with tert-butyl alcohol (TBA) was investigated to produce high quality motor vehicle fuels and fuel additives. The liquid phase etherification reaction was carried out in a continuous flow reactor using an acidic resin catalyst (Amberlyst-15). Effects of feed composition and space time on the product distribution were investigated in a temperature range of 80-110°C. Product distributions indicated the formation of mono-ethers, di-ethers and tri-ether. Selectivity of mono-ethers and di-ethers were about 0.70 and 0.25 for a feed stream containing a TBA to Glycerol ratio of 4:1. Significant increase in conversion was observed with an increase in temperature. Acknowledgement: Gazi University Research Fund (06/2007-13) is gratefully acknowledged. [1] Klepacova, K., Mravec, D., Alexander K., Bajus, M., “Etherification of glycerol and ethylene glycol by isobutylene”, Applied Catalysis A: General, 328, 1-13 (2007). [2] Oktar N., Murtezaoglu K., Dogu G., Gonderten I., Dogu T., “Etherification rates of 2-methyl-2-butene and 2-methyl-1-butene with ethanol for environmentally clean gasoline production”, Journal of Chemical Technology and Biotechnology, 74, 155-161 (1999). [3] Pagliaro M., Ciriminna R., Kimura H., Rossi M., Pina C. D., “From Glycerol to Value-Added Products”, Angewandte Chemie International Edition, 46, 2-20 (2007).


38

P8

SYNTHESIS OF NOX TRAP CATALYSTS USING IMPREGNATION TECHNIQUE

Emine Kaya, Nuray Oktar, Gürkan Karakaş*, Kirali Murtezaoğlu



The aim of this study is to develop Ba impregnated MCM-41 catalysts for the adsorption of NOx from exhaust emissions. NOx trapping materials can be found among the alkali and alkaline earth metal oxides, in which BaO has been extensively studied[1]. MCM-41, shows a highly ordered hexagonal array of unidimensional pores with a very narrow pore size distribution. MCM-41 supported catalysts are mesoporous materials having high surface areas, high adsorption capacity and narrow pore-size distributions [2]. In this study, MCM-41 was prepared as an adsorbent support as described in literature[3]. Ba based MCM-41 catalysts with different Ba loading (5-20 wt.%) were prepared by wet impregnation method. XRD, nitrogen adsorption-desorption analysis (BET-BJH), TGA-DSC, FTIR and SEM-EDS analysis were used for determining the structural and physical properties of synthesized materials. As a result of characterization test, XRD patterns show that crystal structure of MCM-41 was achieved and high surface areas (1150-1278 m2/g) were obtained. XRD examination on pure MCM-41 showed four distinct reflections at 2θ values of 2.24, 3.88, 4.46 and 5.85 which are the characteristic reflections of high-quality mesostructures. It was observed from XRD analysis that in Ba-based adsorbents, barium oxide and barium species were determined besides silicate formation. Adsorption-desorption isotherms showed type IV isotherm according to the IUPAC classification of adsorption isotherms typical of mesoporous solids. Homogeneous pore size distributions were obtained. The SEM photographs showed regular plate shapes for the adsorbent and EDS results showed that Ba had been incorporated into the structure effectively with good dispersion. References 1. Fridell, E., Skoglundh, M., Westerberg, B., Johansson, S., Smedler, G., “NOx Storage in Barium-Containing Catalysts”, Journal of catalysis, 183: 196–209 (1999). 2. Taguchi, A., Schüth, F., “Ordered mesoporous materials in catalysis”, Microporous and mesoporous materials, 77: 1-45 (2005). 3. Güçbilmez, Y., Doğu, T., Balcı, S., “Vanadium incorporated high surface area MCM-41 catalysts”, Catalysis today, 100: 473-477 (2005).


39

P9

Catalytic Activity of V-Fe Mixed Oxide Catalyst for Selective Oxidation of H2S

Dolunay Eslek Koyuncu, Sena Yaşyerli, Zeynep Özaydın

Chemical Engineering Department, Gazi University, 06570, Maltepe, Ankara, Turkey [email protected]

In recent years, a single step selective oxidation of H2S has attracted significant attention of the researchers, since oxidation reaction is practically irreversible and does not have thermodynamic restriction. Iron based catalysts have low cost and are among the oldest catalysts for selective oxidation of H2S. However, these catalysts require excess amount of oxygen to overcome catalyst deactivation and sulfur selectivity is low. In order to improve the catalytic performance of Fe based catalysts, vanadium-iron (V-Fe) mixed metal oxide catalyst was prepared and tested in selective oxidation of H2S. The V-Fe mixed oxide catalyst containing equimolar ratio of V to Fe was synthesized by the complexation technique. The BET, TPR, XRD and SEM analysis were used in the characterization study. Selective oxidation reaction tests were carried out in a continuous fixed bed reactor with a gas mixture containing 0.5% O2, 1%H2S in He, at 250oC. Reactor outlet stream composition was determined by using an FT-IR spectrophotometer connected to the exit of the reactor. BET surface area of the V-Fe catalyst was found as 15m2/g. The XRD pattern of this catalyst showed that iron and vanadium was in the mixed metal oxide form (FeVO4). The complete conversion of H2S was achieved with the V-Fe mixed oxide catalyst prepared in this work. Due to the formation of small amount of SO2 during the initial times of the reaction, initial sulfur selectivity of V-Fe catalyst was about 91%. Then, the selectivity of elemental sulfur was reached to 98% at steady-state. The V-Fe catalyst showed high activity for selective oxidation of H2S to elemental sulfur. Acknowledgment: Contribution of Ms. Gülsüm Usul in the oxidation experiments is acknowledged. Gazi University Research Fund (BAP 06/2006-24) is gratefully acknowledged.


40

P10

In situ FT-IR Studies of Urea Decomposition over Ag/Alumina

H. Mehmet Taşdemir, Nail Yaşyerli

Chemical Engineering Department, Gazi University, 06570, Maltepe, Ankara, Turkey [email protected]

NOx removal from the diesel vehicle exhaust stream using the selective catalytic reduction with a reducing agent, such as hydrocarbons and ammonia, has been an active research area in recent years. Using hydrocarbon as a reducing agent for the removal of NOx resulted in undesired byproducts, such as N2O, using different transition metals supported on alumina catalysts. Ammonia has been known to be highly selective and efficient reducing agent to remove NOx but the use of ammonia may not be commercially viable. Urea, as an ammonia source, can be decomposed and hydrolyzed in-situ to produce ammonia. In addition, HNCO is formed as a by-product during decomposition of urea. HNCO also decomposes to give ammonia. CO(NH2)2→ NH3+HNCO (1) HNCO+H2O→ NH3+CO2 (2) Alumina supported transition metals, such as Pt, Pd and Ag were known to be very active catalysts for NOx reduction. In this study, alumina supported silver catalysts (containing 1 % wt, 2 % wt, 5 % wt) were prepared by sol-gel method. The decomposition of urea over these catalysts was studied in inert gas (helium) in the temperature range of 100 and 400oC by using FT-IR. The analysis of FT-IR spectrum gave the formation of NH3, NH4+, HNCO, -NCO and CO2 using silver containing alumina catalysts. The peaks of melamine and its derivates were also observed during the urea decomposition. CO2, O-H and C-H stretching vibrations were observed at 100, 200, 300 and 400oC. It was observed that the peak of isocyanate formed at 200oC and 300oC for all of the catalysts synthesized in this work. Isocyanate peak disappeared at 400oC. It is concluded that the catalyst prepared in this work is effective in the decomposition of urea as an ammonia source. Acknowledgment: Gazi University Research Fund (BAP 06/2007-53) is gratefully acknowledged.


41

P11

Acetalization of glycerol with valeraldehyde using Amberlyst 15 resin as a catalyst

Halit Levent HOŞGÜN, Mehmet YILDIZ, H. Ferdi GERCEL*

Eskişehir Osmangazi University, Department of Chemical Engineering, Eskişehir, TURKEY

* Anadolu University, Department of Chemical Engineering, Eskişehir, TURKEY [email protected]

Lately, chemical industry has been leading towards renewable resources as feedstocks instead of fossil-derived raw materials. One of the examples for the commonly-used feedstocks is glycerol. Biodiesel process is an important resource for the production of glycerol. Biodiesel is an alternative fuel for diesel engines which is produced in large amounts. Thus, glycerol is also available in large amounts. The increase in the glycerol supply decreased the glycerol prices in the market. If the number of glycerol-based chemicals increases, the price of glycerol will also increase. The reaction between glycerol and aldehydes can yield new chemicals. In this study, acetalization of glycerol with valeraldehyde in the presence of a heterogeneous catalyst (Amberlyst 15) was investigated. Effect of four different parameters (stirring speed, catalyst particle size, catalyst amount and temperature) on the glycerol conversion has been studied. All experiments took place in a batch reactor equipped with a reflux condenser which was immersed into a water bath. Glycerol, valeraldehyde and a solvent (1,4 Dioxane) were used in analytical grades. Samples were analyzed by a gas chromatograph. Increasing the amount of the catalyst used increased the glycerol conversion. This result is not surprising, since the number of active sites increases as the catalyst amount increases. It was observed that the stirring speed had no effect on the glycerol conversion. This means that mass transfer limitations are not significant in this reaction. On the other hand, temperature had a positive effect on the glycerol conversion. Acknowledgement This study was financially supported by TÜBİTAK (106M375)


42

P12

Dielectric properties of HCl acid treated bentonite samples

Ertuğrul İzci, Alime İzci*

Anadolu University, Physics Department, 26470 Eskisehir, Turkey * Eskişehir Osmangazi University, Dept. of Chemical Engineering, Eskisehir, Turkey

[email protected] The acid treatment of the clay results in the change in surface area, porosity and the type and concentration of the ions in the change sites. Acid treated clays were used as catalysts in many industrial sectors. The electrical properties of minerals reveal enormous technical importance due to their manifold applications as solid catalysts. The objective of this work has been investigated the dielectric properties of HCl acid treated bentonite samples. The raw materials used in the present study are bentonite coming from the Esan Company. Natural bentonite was treated at 950 0C. 5 grams of the bentonite was refluxed with 50 ml of 0.25M, 0.5M, and 1M HCl for 180 min. The resulting activated clay was centrifuged and washed with water several times until it was free of Cl− and dried at 120 0C in an air oven. Before dielectric measurements, bentonite and acid-activated bentonite were calcined at 600 0C for 10 h. They were prepared and dielectric properties of acid treated bentonite were carried out in the 103 Hz – 107 Hz frequency region at room temperatures by using HP4194A LF Impedance Analyzer. After acid activation, the permittivity considerably decreases and attains values similar to those observed in bentonite. The dielectric properties differed considerably from the values observed for bentonite sample at high frequencies. The results of this investigation were explained and given to be used for further studies in the some catalysis studies. Conductivity and dielectric permittivity studies are utilized in the investigation of the necessary conditions for catalytic activity.


43

P13

Selective CO Oxidation over supported CuOx Catalysts

Emel Özdemir, Akif Gülbağ, Emre Özyılmaz, Ayşe Nilgün Akın

Kocaeli University, Chemical Engineering Department, 41040 Kocaeli, Turkey [email protected]

PEM Fuel Cell that uses hydrogen as a fuel has attracted considerable attention for both stationary and mobile applications. Hydrogen is mostly produced by steam reforming and following water gas shift reaction. The end product contains rich hydrogen but 0.5 vol%– 2.0 vol % CO that effects Pt-catalyzed anode of PEM fuel cell dramatically. An effective method for CO removal is selective oxidation of CO with highly active and stable catalysts. In this study 13 CuOx based catalysts were prepared with different supports such as CeO2, CoOx, NiOx, CoOx-CeOx, NiO-CeOx ,by impregnation method. Additionally, co-precipitation method were used for the preparation of support materials. Catalysts were characterized by XRD technique. The gas phase reaction took place in stainless steel tubular reactor with the temperature of 150 oC for 3 h. CO oxidation reactions were carried out with the gas composition of 1 vol.% CO, 1 vol.% O2, 60 vol.% H2, 25 vol.% CO2, 10 vol.% H2O and 3vol.% He and 100 ml/min flow rate. Gas chromatography was used for determining CO conversion and selectivity. 20% CuOx supported on CoOx-CeO2 catalyst was superior among the all catalysts prepared for low temperature preferential oxidation of CO in H2-rich gases. The catalyst has great performance with the conversion of nearly %100 and high selectivity and stability. Results show that CuOx/CoOx-CeO2 catalyst can be an alternative to expensive catalysts like Pt and Au based catalysts.


44

P14

Direct Oxidation of Hydrogen to Hydrogen Peroxide over CuOx/SiO2 Catalysts

Meltem Yıldız, Ayşe Nilgün Akın

Kocaeli University, Chemical Engineering Department, 41040 Kocaeli, Turkey [email protected]

Hydrogen peroxide is a noted green oxidant that is useful in many large scale processes such as bleaching agent and as a disinfectant. There are drawbacks of the commercial process such as the cost of the components and loss of them by oxidation. It is, therefore, of great practical interest to produce H2O2 more economically and unpolluted by a novel process, such as that based on the direct oxidation of H2. The development of direct oxidation of hydrogen process involves a three-phase system that includes a solid catalyst, a liquid phase, and the reagent gases. In this study CuO based SiO2 and HZSM-5 supported catalysts with different Si/Al ratios were prepared by impregnation method and were characterized by XRD technique to identify the phases. Direct oxidation of hydrogen in a liquid reaction medium were carried out in a slurry reactor with O2/H2 ratio of 2/1, and 50 ml/min total gas flow rate at atmospheric pressure and room temperature. Hydrogen conversions and H2O2 amount were tested by using a gas chromatography and iodimetric titration method respectively. Results are discussed based on effects of catalyst composition and reaction medium (type of halogenide and acid) on hydrogen conversion and hydrogen peroxide selectivity. Our results show that catalytic performance of Cu based catalyst was greatly dependent on the investigated parameters. The highest conversion in the study was obtained with %20 CuO/SiO2 catalyst in a reaction mixture of 0,25 N H2SO4, 0,1 M NaBr and absolute ethanol.


45

P15

DEVELOPMENT OF ALUMINA SUPPORTED ALKALINE CATALYSTS USED FOR BIODIESEL PRODUCTION

Oğuzhan İlgen, Ayşe Nilgün Akın

Kocaeli University, Chemical Engineering Department, 41040 Kocaeli, Turkey

[email protected]

Alkyl esters of long chain fatty acids are called biodiesel. Biodiesel is obtained by transesterification of the triglycerides found in vegetable oils and animal fats with an excess of a primary alcohol (most commonly methanol) in presence of a homogeneous or heterogeneous catalyst. Homogeneous catalytic systems have many drawbacks. Removal of these catalysts to purify the biodiesel fuel and glycerol as a by-product is difficult and requires a large amount of water. Consequently, a considerable amount of wastewater is inevitably produced. To overcome these problems, the transesterification over environmentally benign solid catalysts is a promising route. Heterogeneous catalysts could be easily separated from the reaction mixture by filtration and then reused. Also, they are less corrosive, leading to safer, cheaper, and more environment-friendly operations. For developing a process of biodiesel production with environmental benignity, much interest has been focused on solid base catalysts for transesterification of vegetable oils with methanol. In this study, we investigated the possibility of using γ-Al2O3 supported alkaline compounds as heterogeneous catalysts for the transesterification of canola oil with methanol. The effects of various factors such as mass ratio of catalyst to oil, reaction temperature, reaction time and molar ratio of methanol to canola oil were studied to optimize the reaction conditions. Our results showed that higher than 90 % FAME yields were obtained at certain reaction conditions by using alumina supported alkaline catalysts.


46

P16

WO3-Nb2O5 solid solutions: Synthesis and Characterization

İlknur Çayırtepe, Margarita Kantcheva

Department of Chemistry, Bilkent University, 06800 Bilkent, Ankara, Turkey [email protected]

Mixed WO3-Nb2O5 oxides were prepared by dissolving solid ammonium metatungstate in acidic H2O2 solutions of the peroxoniobium(V) complex, [Nb2(O2)3]4+. The precursor solutions were evaporated to dryness followed by calcination. The content of WO3 ranged from 10 to 80 wt %. According to XRD, with the increase in the WO3 loading, the peaks of the Nb2O5 phase decreased in intensity and broadened. This suggests that incorporation of tungsten(VI) in to the Nb2O5 lattice took place causing the contraction of the lattice parameters and reduction of the average crystallite size of niobia. It should be pointed out that the conventional methods involving calcination of mixtures of powders of Nb2O5 and WO3 do not lead to formation of niobia-based solid solutions. The samples were characterized by Raman, DR-UV-vis and FT-IR spectroscopy of adsorbed lutidine. The material containing 20 wt % of WO3 and promoted with 0.1 wt % Pd(II) was able to catalyze the reduction of NO by CO at low temperature (1500C).


47

P17

Reactivity of Adsorbed NOx Species toward Methane on Mesoporous High Zirconia Co(II)- and Pd(II)-Modified Silica-Zirconia Materials

Olga Samarska, Ömer Dağ, Margarita Kantcheva

Bilkent University:Chemistry Department:Laboratory for Advanced Functional Materials,

Ankara Turkey [email protected]

The interaction of methane at various temperatures with NOx species formed by room temperature adsorption of NO+O2 mixture on mesoporous Pd(II)-free and Pd(II)-promoted sulfated Co(II)-incorporated silica-zirconia (mole ratio Zr/Si = 3.37) has been investigated using in situ FT-IR spectroscopy. In order to evaluate the ability of strongly bound surface NOx complexes for methane activation, the following experiments have been performed: (i) a “Blank CH4” experiment consisting of interaction of the activated samples with methane at elevated temperatures; (ii) a “Blank NOx” experiment involving thermal transformation of the adsorbed NOx species; (iii) a “CH4-NOx” experiment monitoring the interaction of methane at various temperatures with the adsorbed NOx complexes. The results of the present investigation suggest that mesoporous sulfated cobalt-modified silica-zirconia composites with low Co/Pd mole ratio could find application as thermally stable catalysts for the reduction of NO with methane. The role of the cobalt(II) incorporated in the silica-zirconia framework is not only to stabilize the mesoporous structure but also to prevent the segregation of the active palladium(I) sites.


48

P18

INVESTIGATION OF BIODIESEL PRODUCTION FROM CANOLA OIL USING AMBERLYST–26 CATALYST

Oğuzhan İlgen, Ayşe Nilgün Akın, Nezahat Boz

Kocaeli University, Chemical Engineering Department, 41040, Kocaeli, Turkey

[email protected]

The transesterification of canola oil to fatty acid methyl esters was studied using an Amberlyst–26 solid catalyst. The influence of reaction conditions such as the reaction time, the oil to methanol ratio, the amount of catalyst, the effect of co-solvent, alcohol and oil type were performed. When the reaction was carried out at 45 oC, with a molar ratio of canola oil to methanol of 6:1, a reaction time 1.5 h and a catalyst amount 3%, the oil conversion was about 67%. Methanol was found to be much more reactive than ethanol and isopropyl alcohol (IPA) in the transesterification reaction. The conversion of canola oil was not changed much with the addition of tetrahydrofuran (THF) as a co-solvent. However in the presence of n-hexane as a co-solvent in the reaction mixture, conversion of canola oil was decreased. Canola oil gave the highest conversion among the other oils as sunflower and corn. Keywords: Biodiesel; Heterogeneous Catalyst; Amberlyst-26


49

P19

Thermal Behavior of BaO/γ-Al2O3 and Fe promoted BaO/γ-Al2O3

Emine Kayhan, Göksu Seda Şentürk, Stanislava Andonova, Emrah Özensoy

Bilkent University, Chemistry Department, 06800 Ankara, TURKEY [email protected]

Pt/BaO/γ-Al2O3 system is one of the most widely used NOx Storage Reduction catalyst for automotive emission control, particularly for diesel engine and gasoline direct injection (GDI) applications. Numerous attempts to improve the performance of the conventional catalysts by adding various additional catalytic promoters have been reported. The aim of the current work is to establish the effect of the BaO (8 and 20 wt%),storage component and the Fe (5 and 10 wt%) promoter loadings on the composition and dispersion of BaO/γ-alumina catalysts. Incipient wetness impregnation method was used for catalyst synthesis. Two different types of γ-Al2O3 samples were utilized as support materials; a custom-made γ-Al2O3 prepared via sol-gel protocol and a commercial (Purolox®) γ-Al2O3. After synthesis, catalysts were calcined at various temperatures ranging from 298 K to 1273 K under inert argon atmosphere. Catalyst samples were characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectroscopy/Imaging (EDX). The specific surface area of the catalysts were also determined using the single-point BET method. Ba and Ba-Fe containing samples prepared by incipient-wetness impregnation have well-dispersed Ba(NO3)2 phase compared to the samples by drop by drop impregnation method. Increasing the temperature up to 873 K of the deposited Ba(NO3)2 on the support leads to complete decomposition of Ba(NO3)2 phase and the formation of an amorphous BaO phase. A further increase in temperature results in a catalyst composition where BaAl2O4 phase dominates. Increasing the Fe loading in the Ba containing samples yields an attenuation in the dispersion of Ba(NO3)2 phase and the formation of crystallites on the surface.


50

P20

Direct Oxidation of Methane to Methanol by N2O on Fe- and Co-ZSM-5: A Density Functional Study



[email protected]

During the past two decades the C-H bond activation of small alkanes, especially of methane, has received a great deal of attention both experimentally and theoretically. The direct methane conversion to methanol is an important chemical process of the 21st century since methanol has traditionally been used as a solvent and as a feedstock for bulk organic chemicals (primarily formaldehyde), with modest growth potential. Panov and co-workers have reported that methane is selectively oxidized to methanol at room temperature over the interaction with a-form of the surface oxygen produced on Fe-ZSM-5 zeolite by N2O decomposition. The purpose of this study is to determine and compare the relative energy profiles of partial oxidation of methane to methanol by nitrous oxide by using density functional theory on clusters representing Co-ZSM-5 and Fe-ZSM-5 catalysts. Zeolite surfaces were modeled as Si4AlO4H12Fe(Co) clusters. All of the cluster atoms, reactant and product molecules were kept relaxed. The dangling orbitals of the peripherial Si atoms were saturated with H atoms. Energy profiles were studied by means of DFT calculations as implemented in Gaussian’03 program at B3LYP level using 6-31G** as basis set for all of the atoms. Relative reaction energies of direct oxidation of benzene to phenol were determined for Si4AlO4H12Fe(Co) clusters. The first reaction is N2O decomposition on Fe (Co) site. The second step is methane adsorption O site. A further reaction step which is a rate-limiting step is the formation of methanol on the cluster. The last step is desorption of methanol from the surface.


51

P21

A Novel Material with a Novel System in the Stoichiometric and Separate Evolution of H2/O2 from the Splitting of Water

Osman Karslıoğlu, Sadig Kuliyev*, Deniz Üner

Middle East Technical University, Chemical Engineering Department, Ankara, Turkey

* Vestel Defence Industries, Ankara, Turkey [email protected]

Solar water splitting to yield stoichiometric H2 and O2 is the ultimate aim for a renewable energy cycle. One of the novel materials which are currently being studied for this purpose is TiO2 nanotubes. In this study, TiO2 nanotubes are synthesized by electrochemical methods on a titanium foil. One side of the foil was oxidized for this purpose; the other side was loaded with Pt. The characterization of the ordered nanotube arrays was studied by SEM. The same analysis was made for the other side of the foil as well. Effectiveness of the formed films for the water splitting reaction is tested in a quartz photolytic cell, which is constructed solely for this purpose, under UV and visible light irradiation. Cell is composed of two sections containing basic (oxide side) and acidic (Pt side) solutions which are separated by the foil and also with a Nafion membrane forming a closed circuit. SEM pictures and the reaction rate results are to be presented.


52

P22

NOx Abatement in Diesel Engine by NOx Storage and Reduction (NSR) Technology

Başar Çağlar, Deniz Üner


[email protected]

In the present study, the effect of catalyst composition and preparation conditions on NSR efficiency will be investigated. Pt/BaO/ γ-Al2O3 catalysts were prepared with barium loadings, 5, 10, 15 and 20 wt % via incipient wetness impregnation. Additionally Pt/ BaO/ CeO2-γ Al2O3 and Pt/ BaO/ ZrO2-γ Al2O3 catalysts were also prepared by taking the stabilizing effect and high oxygen storage properties of ZrO2 and CeO2 into consideration. Adsorbed NOx species are characterized by DRIFTS. The NSR activities were tested in a home built reaction system with periodic switch of gases between the compositions of 10 % oxygen, 500 ppm NO for lean and .10 % oxygen, 500 ppm NO, 1000 ppm C3H8 for rich conditions. The effluent gases were analyzed by a Pfeifer RGA unit. The experimental results will be consolidated in a working mechanism of the catalytic reaction.


53

P23 What are the active sites of a commercial 5% Pt γ-Al2O3 catalyst in liquid phase

reactions?

Hilal Kıvrak, Zoltan Kiraly*, Agnes Mastalir*, Deniz Üner

Middle East Technical University, Chemical Engineering Department, Ankara 06531, Turkey * Department of Colloid Chemistry, University of Szeged, Aradi Vt. 1, H-6720 Szeged, Hungary

[email protected]

Supported noble catalysts (Pt, Pd, Rh, etc) are widely used in liquid phase hydrogenations for many organic transformations such as liquid phase hydrogenation of styrene to produce ethyl benzene, an important ingredient in chemical industry. In the present work, characterization of commercial γ-Al203 supported 5%Pt was characterized by TEM, gas phase microcalorimetry performed at 323 K by using a Tian-Calvet type heat flow calorimeter (Seteram C-80), and liquid phase hydrogenation/CS2 poisoning experiments performed in the PC-interfaced three-phase slurry reactor to investigate the active sites of platinum catalyst involving in liquid phase hydrogenation. Measurements in the gas phase revealed that the differential heats of hydrogen and carbon monoxide adsorption decreased sharply up to 10 mol of CO or H adsorbed/100 mol Pt coverage. This behavior was attributed to the saturation of high energy defect like sites of platinum. Liquid phase hydrogenation/CS2 poisoning experiments showed that saturation of platinum was reached at 10 mol of CS2 adsorbed/100 mol of Pt saturation coverage, correlated very well with the coverage of the defectlike sites identified from gas phase microcalorimetry data. Our present results indicate that in liquid phase reactions only the defect sites are active. The dispersions measured as 46% by gas phase hydrogen and carbon monoxide adsorption and as 48% by TEM are not as significant indicators of the activity in the liquid phase reactions.


54

P24

Photocatalytic Reactivity of Crystalline and Fractal TiO2 films

Mert Mehmet Oymak, Osman Karslıoğlu, Deniz Üner

Middle East Technical University, Chemical Engineering Department, Ankara 06531, Turkey [email protected]

The application of pollution-free photocatalysis has become an important candidate for alternate ways of CO2 utilization methods. Valuable products such as H2, methane, methanol or higher hydrocarbons can be obtained, but in low yields. In order to increase the kinetics of the reaction, reaction mechanism has to be clearly understood. In this study, the glass beads were coated with titania by using a sol-gel procedure. Scanning Electron Micrographs of the films revealed that the film characteristics can be controlled by sol-gel procedure in the range from crystalline TiO2 to fractal geometry. The local structure of the photocatalysts is further characterized by UV-VIS, XRD and XPS techniques. Experiments are in progress for the photocatalytic activity of these films during the reduction of CO2 with H2O under irradiation by UV light. Acknowledgement: The financial support for this project was provided by TUBITAK under grant no CAYDAG 106Y075.


55

P25

SONOLYTIC, PHOTOCATALYTIC AND SONOPHOTOCATALYTIC DEGRADATION OF DYESTUFFS

Tuba Yetim, Taner Tekin

Atatürk University, Faculty of Engineering, Department of Chemical Engineering,

25240 Erzurum, Turkey [email protected]

Discharged dye effluents from the textile industries cause important environmental dangerous. The interest in making colourless the dye effluents has increased in the recently. The traditional physical methods are commonly used for removing the pollutants. But these methods are not very destructive and they forward the organic compounds to another phase. This phenomenon causes a secondary pollutant. Therefore the usage of photocatalytic processes has increased in the recent days. We have observed the effect of ultrasound energy (sonolysis) on the photocatalytic degradation of dyestuffs by UV radiation in the presence of TiO2. The dyestuffs constitute an important part of textile effluents. In the present study, the degradation of artificial effluent solution which contains dyestuffs mixture of AR27, disperse red 92 and orange g has been investigated with sonolytic, photocatalytic and sonophotocatalytic methods in the presence of TiO2. Sonolytic, photocatalytic and sonophotocatalytic degradations of artificial effluent solution have been investigated as a function of initial concentration of dyestuffs, light intensity, the amplitude of ultrasound energy and temperature. It has been obtained from the experiments that the sonolysis alone hasn’t had a very important effect on the degradation. However, when it has been used with the photocatalysis in the presence of TiO2, the degradation raised remarkably. The effect of sonolysis on the reaction is caused by the OH* radicals which occur from the homolysis of water. Therefore it is determined that the sonolysis is more effective when it is used with the photocatalysis in the presence of TiO2. It has been observed that the degradation ratio has increased approximately 8% when the sonolysis and the photocatalysis in the presence of TiO2 (sonophotocatalysis) are used together.


56

P26

Kinetic Studies of Incorporation of Titanium in Mesoporous Silica SBA-15

Orçun Ergün, Ayşen Yılmaz*, Deniz Üner

Middle East Technical University, Chemical Engineering Department, Ankara, Turkey * Middle East Technical University, Chemistry Department, Ankara, Turkey

[email protected]

In this work, the extent of the bandgap modification by incorporating TiO2 into mesoporous silica materials is investigated. The ultimate goal is to obtain nanometer sized TiO2 crystals and/or framework Ti atoms with narrow bandgaps sensitive to visible light. Understanding the effect of kinetics of incorporation on the morphology and the amount of incorporated Ti atoms is the objective of this study. For this purpose, titanium was incorporated in mesoporous silica SBA-15 by a sol-gel method using the self organizing polymer pluronic 123, TEOS and adding titanium(IV) isopropoxide into the solution in the preheating and precalcination stage. Samples containing the same amounts of Ti and Si, were aged for different durations. Diffuse reflectance UV-Vis spectroscopy revealed that increasing aging time from 12h to 48h increases absorption in the UV and visible light region of the spectrum. Increasing the aging time to 60h causes a decrease in absorption. This finding revealed that the incorporation kinetics is a strong function of aging time during synthesis. The kinetics involved in the incorporation phenomena is further investigated by synthesizing samples containing different Ti/Si ratios at different aging time intervals and characterizing them by XRD, ICP, FTIR and diffuse reflectance UV-Vis spectroscopies. Acknowledgements: The financial support for this project was provided by TUBITAK under research grant CAYDAG 106Y075 and through the BDP program. Authors gratefully acknowledge Prof. Margareta Kantcheva for the assistance in Diffuse Reflectance UV-VIS measurements.


57

P27

Biodiesel production from Canola oil over basic heterogeneous catalysts

Selahattin E. Umdu, Sait, C. Sofuoğlu, Erol Şeker

İzmir Institute of Technology, Chem. Eng. Dept., Izmir, Turkey [email protected]

Emissions of the greenhouse and toxic gases due to the use of fossil fuels cause global warming, environmental and health problems. Furthermore, sustainable economic growth could be achieved by incorporating more energy conversion technologies based on national alternative renewable energy sources. Among alternative energy sources, biodiesel seems to be promising because it is biodegradable, renewable, and non-toxic fuel with low pollutant emission rates. Biodiesel is commonly produced from many vegetable oils or animal fats using homogeneous catalysis. In this study, canola oil and methanol were used to produce biodiesel over basic heterogeneous catalysts. We synthesized CaO and MgO oxides on support materials SiO2 and Al2O3 using a single step sol-gel method. 50 and 80% loadings for both CaO and MgO oxides were used to study the effect of catalyst composition and its physic-chemical properties on the catalytic activity in producing biodiesel from canola oil. All the catalysts were tested at 50oC. Our preliminary results show that 80%CaO/Al2O3 having crystallites less than 5 nm in size could be synthesized; hence resulting in highly dispersed mixed oxide catalysts and the conversion of oil to biodiesel over this catalyst is ~97%. We will present the conversion activities of the catalysts as a function of catalyst loading and crystallite size.


58

P28

MCM-41 Type Catalytic Materials via Impregnation and Microwave Assisted Synthesis Methods

Aslı Nalbant, Yuda Yürüm

Sabancı University, Materials Science and Engineering Department

Orhanlı, Tuzla, 34956 Istanbul, Turkey [email protected]

MCM-41 type catalytic materials with their hexagonal arrangement of unidimensional pores and large surface areas (greater than 1000 m2 g−1) fascinate the designers of new selective heterogeneous catalysts in the production of fine chemicals on large scale. Metal incorporated MCM-41 catalysts are attractive alternates which can be used in carbon nanotube (CNT) synthesis. Microwave assisted synthesis of mesoporous molecular sieves is a promising method due to several advantages over the conventional hydrothermal method. The advantages of microwave-induced heating include homogeneous heating throughout a reaction vessel, resulting in more homogeneous nucleation and shorter crystallization times. In this presentation, two different methods were compared. In the first method, MCM-41 mesoporous materials were synthesized with microwave radiation and then metal was impregnated into these as-synthesized MCM-41 materials using different Si/Metal ratios as 25, 50, 75 and 100. In the second method metal was added into the raw materials directly and then the mixture was treated in the microwave oven using different Si/Metal ratios as 25, 50, 75 and 100. The products obtained were characterized by XRD, N2 physisorption, SEM, EDS and TEM. The incorporation of metals into MCM-41 structure synthesized with direct microwave-induced heating and impregnation methods were compared. It is important to note that the synthesis of mesoporous material by microwave-induced heating reduced the synthesis time from days to 30 minutes. The products will be used as catalytic materials in the production of CNT formation.


59

P29

GRAPHENE: A NEW APPROACH FOR THE NANOSTRUCTURED ELECTROCATALYSTS IN FUEL CELLS, A PRELIMINARY ATTEMPT

Burcu Saner, Yuda Yürüm

Sabancı University, Materials Science and Engineering Department

Orhanlı, Tuzla, 34956 Istanbul, Turkey [email protected]

Graphene, the world’s thinnest sheet -only a single atom thick-, has a great potential to provide a new way in the application of fuel cell technology. The important property of graphene is its stability at ambient conditions and it can exist by being rippled rather than completely flat in a free standing state. After the discovery of monolayer graphene, researchers developed new synthesis techniques of graphene. Our major goal was to investigate the monolayer graphene synthesis techniques and the preparation of advanced electrocatalysts using metal incorporated nanostructured materials to be used in polymer electrolyte membrane fuel cells (PEMFCs). The incorporation of metals into the graphene layers can be a good material to enhance thermal and electronic conductivities of the membrane electrolyte in PEMFCs. Also, other nanostructured materials like carbon nanotubes and carbon fibers can be utilized for the fabrication of electrocatalysts for PEMFCs. Today, graphene sheets has only been present in researchable form, if its mass production is achieved, it will provide new approach for the development of nanostructured electrocatalysts as oxygen reduction catalysts with reduced noble metal content and good stability.


60

P30

Kinetics of pitch and phenolic resins pyrolysis

Firuze Okyay, Yuda Yürüm

Faculty of Engineering and Natural Sciences, Sabancı University, Istanbul 34956, Turkey [email protected]

The present study focuses on the kinetics of pyrolysis of pitches by using thermogravimetric analysis for the purpose of graphene-like material synthesis. A novel method is tried to be implemented in order to synthesize polycyclic aromatic hydrocarbons (PAHs) from coal and petroleum pitch and polyacenic semiconductor materials (PAS) from phenol-formaldehyde resin by pyrolytic heat treatment. Experiments were carried out under nitrogen atmosphere at temperature range of 550-850°C in a thermogravimetric instrument. Distribution of the products was used for the investigation of kinetics of the formation of polycyclic aromatic hydrocarbons and polyacenic semiconductor materials. Keywords: Hydro-graphene; Pyrolysis; PAHs; PAS; Kinetics


61

P31

Removal of Boron from Water by Natural Adsorbents

Seren Yüksel, Yuda Yürüm

Faculty of Engineering and Natural Sciences, Sabancı University, Orhanlı, Tuzla 34956, Istanbul, Turkey

[email protected]

The aim of this research is to monitor and control the release of boron pollution to the environment with waste water. Boron ions in solutions with different concentrations were removed by chemisorption, using natural porous adsorbents such as natural Gördes zeolite (clinoptilolite), raw and demineralized Beypazari lignite. Experiments were done to observe the adsorption efficiency of boron ion as a function of time, adsorbent mass, initial boron concentration, pH and temperature. The results lead to generation of adsorption isotherms and rate of adsorption and activation energy of adsorption of boron ions using these materials were determined. Catalytic activity of the minerals present in the raw coal on the chemisorption of boron ions was also determined. Keywords: adsorption, boron, zeolite, lignite, demineralized


62

P32

A PARAMETRIC STUDY OF LOW-TEMPERATURE WATER-GAS SHIFT REACTION

Özlem Şen, Ahmet K. Avcı, Z. İlsen Önsan

Department of Chemical Engineering, Boğaziçi University, Bebek 34342, Istanbul, Turkey

[email protected]

The water-gas shift (WGS) reaction was studied using three different catalysts prepared by sequential incipient-to-wetness impregnation with fixed platinum and different cerium oxide loadings (1.4wt.%Pt-10wt.%CeOx/γ-Al2O3, 1.4wt.%Pt-5wt.%CeOx/γ-Al2O3 and 1.4wt.%Pt-1.25wt.%CeOx/γ-Al2O3). The experimental work involved a parametric study of the effect of cerium oxide loading, catalyst reduction time, reaction temperature, contact time (W/FCO) and the feed H2O/CO ratio on CO conversion. The parametric study was first conducted on 1.4wt.%Pt-10wt.%CeOx/γ- Al2O3, except for the H2O/CO ratio that was tested only on the catalyst with the lowest cerium oxide content. The BET surface areas of the catalyst samples were in the 150-185 m2.g–1 range. X-ray diffraction analysis of unreduced catalyst samples to determine the existing crystal phases indicated the presence of CeO2. Fresh catalyst samples were reduced in situ at 350oC under pure H2 flow for 2-3 hours of reduction time showed no appreciable effect on CO conversion. W/FCO ratios tested between 0.60-1.25 mg.min.µmol–1 gave CO conversions increasing with contact time. Low-temperature WGS experiments in the 250-350oC interval showed the significant effect of reaction temperature: CO conversion increased with temperature until WGS equilibrium was reached after 300oC and then decreased with the equilibrium curve. The CO conversions obtained at CeO2 loadings of 5-10 weight per cent were the same but decreased at 1.25 weight per cent CeO2 content. The effect of H2O/CO ratio was tested only on 1.4wt.%-1.25wt.%CeOx/γ-Al2O3 for molar ratios between 1 and 3; the results obtained at 250oC showed that CO conversion increased gradually as H2O/CO ratio reached a value of three.


63

P33

Intrinsic and Extrinsic Catalysis for Lignite Gasification

Arzu Kanca, Deniz Üner

Middle East Technical University, Chemical Engineering Department, Ankara 06531, Turkey [email protected]

The combustion and gasification characteristics of coal samples were investigated by using Thermogravimetric analysis (TGA) in the presence and in the absence of catalysts. Lead and cobalt mixed oxides were used as extrinsic catalysts. On the other hand, the mineral contents of coal cause the intrinsic catalytic effects. Prior to gasification experiments, lignite samples were characterized by ultimate and proximate analysis, as well as by x-ray fluorescence, DRIFTS and 13C and 1H MAS-NMR techniques. The lignite samples were used either as received or after leaching the sulfur and mineral compounds. The aliphatic to aromatic carbon ratios determined by 13C CP-MAS-NMR were correlated with the DRIFTS data. The relative abundance of aliphatic hydrocarbons and the role of intrinsic and extrinsic catalysts on the gasification kinetics are investigated. Three different reaction atmospheres in TGA experiments were used to determine the gasification behavior under (i) pure nitrogen for pyrolysis, (ii) air (21% O2 and 79% N2) for combustion and (iii) 10% O2 and 90% N2 mixture for partial oxidation.


64

P34

Synthesis of SBA-15 silica products for the production of mesoporous carbons

Aysun Karaoğlu, Aslı Nalbant, Yuda Yürüm

Sabancı University, Materials Science and Engineering Department Orhanlı, Tuzla, 34956 Istanbul, Turkey

[email protected]

Nonionic alkyl poly(oxyethylene) surfactants and poly(oxyalkylene) block copolymers are important families of surfactants that are widely used in emulsifying, defoaming/antifoaming, coating, thickening, solubilizing, cleaning, lubricating, wetting, pharmaceutical, coal and petrochemical industries, and household applications. In composite materials synthesis, nonionic block copolymers are an interesting class of structure-directing agents. Highly ordered mesoporous (20-300 Å) silica structures have been synthesized by the use of commercially available nonionic alkyl poly(ethylene oxide) (PEO) oligomeric surfactants and poly-(alkylene oxide) block copolymers in acid media. Characteristics of SBA -15 mesoporous silica products were determined by the X-ray diffraction, nitrogen adsorption/desorption isotherms, and scanning electron microscope (SEM) analyses. The obtained SBA -15 mesoporous silica products will be used for the production of mesoporous carbons.


65

P35

LOW TEMPERATURE CO OXIDATION OVER ACTIVATED CARBON SUPPORTED Pt-CeOx

Berrin Gülyüz, A. Erhan Aksoylu, Z. İlsen Önsan


[email protected]

Low-temperature CO oxidation was studied at 383 K in the presence and absence of H2 and CO2 over air-oxidized activated carbon supported Pt-CeOx prepared by sequential impregnation. Molar reactant concentrations in the feed were varied from 1 to 5 per cent CO and 1 to 2.5 per cent O2 in CO oxidation experiments conducted in the presence of helium only. Rate data obtained at 383 K in the initial rate region were used to estimate kinetic parameters of the power-function rate expression. The reaction orders with respect to CO and O2 partial pressures were found to be –0.29 and 1.07, respectively, indicating a surface primarily covered with adsorbed CO reacting with weakly adsorbed oxygen. LHHW rate expressions based on plausible CO oxidation mechanisms were also tested on the basis of initial rate data. Preferential CO oxidation experiments where the H2 concentration was varied between 5–60 per cent indicated that the presence of H2 did not alter the mechanism of CO oxidation over the catalyst, but rather lowered CO oxidation rates by almost one-half at H2 concentrations above 10 per cent. The effect of CO2 was studied by adding 2–4 per cent CO2 into a feed containing 5 per cent CO and 2.5 per cent O2; results indicated that CO conversions were gradually lowered by almost one-half up to 3 per cent CO2 in the feed, followed by a rapid decline at higher CO2 concentrations, indicating the necessity for further kinetic studies using CO2-containing feed mixtures.


66

P36

Synthesis of Pt /Co-Pb/SBA15 mesoporous catalysts and characterization of the samples with TPR technique

Mukaddes Can, Ayşen Yılmaz*, Deniz Üner


* Middle East Technical University, Chemistry Department, Ankara, Turkey [email protected]

Mesoporous materials may exhibit a large variety of morphologies depending on the synthesis conditions. The method of the catalyst preparation affects the dispersion and the reducibility of the metals on the support. The objective of this work is to prepare catalysts with good red-ox properties to be used hydrogen generation reaction via partial oxidation reactions. In the present work, SBA-15 and Co and/or Pb incorporated SBA-15 mesoporous silica materials were synthesized by Pluronic 123 nonionic triblock co-polymer as template. TEOS (Tetraethylorthosilicate) was used as a silica source. Then, platinum was loaded into these catalysts by using incipient wetness impregnation method. Up to now, Co-SBA15, Pb-SBA15 and Co/Pb-SBA15 samples were synthesized. Different metal/Si ratios were used in synthesis of the samples. The synthesized samples were characterized by using XRD and BET analysis. Work is in progress to asses the red-ox properties of the metal oxides in the mesoporous catalysts by using TPR (temperature programmed reduction) and TPO (temperature programmed oxidation) techniques.


67

P37

Synthesis Gas Production by Dry Reforming Of Methane over Nickel Based Mesoporous Catalysts

Hüseyin Arbağ, Sena Yaşyerli, Nail Yaşyerli, Gülşen Doğu


[email protected]

Production of synthesis gas by the reforming reaction of two greenhouse gases, namely CO2 and CH4, received considerable attention in recent decades. Nickel is among the active metals used as a catalyst in such reforming reactions. In this study, high surface area, Ni incorporated MCM-41 like mesoporous catalyst, containing Ni/Si ratio of 0.49, was synthesized following a hydrothermal synthesis route. This catalyst was pelletized and dry reforming of methane was investigated in a flow reactor at 600oC using catalyst particles having diameters in the range of 1-2 mm. This catalyst showed quite stable and high activity in the dry reforming reaction. Higher initial CO2 fractional conversion (0.47) than the initial methane conversion (0.33) is considered to be due to the occurrance of reverse water gas shift reaction in parallel to dry reforming. Higher CO selectivity (2.44) than H2 selectivity (1.66) also justified this conclusion. In this presentation, synthesis and characterization of the nickel incorporated mesoporous catalyst and its activity in dry reforming of methane will be reported. Acknowledgements: TUBITAK and Gazi University research grants are gratefully acknowledged.


68

P38

Investigation of fuel properties of biodiesel produced over Alumina-based solid catalyst

Nezahat Boz, Miray Kara, Ertan Alptekin*, Nebahat Değirmenbaşı

Dept. of Chemical Engineering, Kocaeli University, Veziroglu Campus, 41040, Kocaeli, Turkey

* Dept. of Mechanical Education, Kocaeli University, Umuttepe Campus, 41380, Kocaeli, Turkey ** Dept. of Chemistry, Faculty of Science Gazi University, 06500, Teknikokullar, Ankara, Turkey

[email protected]

During last decade, we have seen a growing interest toward biodiesel production because of the environmental concerns and limited resources of petroleum. Biodiesel can be produced by transesterification of vegetables oils, animal fats and grease with short-chain alcohols (methanol, ethanol) in the presence of alkali catalysts (KOH, NaOH). Lately, significant research focused on the replacement of homogeneous catalysts by heterogeneous catalysts. The main advantages of heterogeneous catalysis compared to homogeneous catalysis are catalyst separation, flexibility in catalyst, regeneration, less expensive and being environmentally friendly. In our earlier study, the potassium impregnated alumina catalysts were prepared and KF/Al2O3 showed the highest activity (99.6% Methyl ester yield) in the transesterification of canola oil with methanol [1]. In the present study, characterization of biodiesel derived from canola oil, soya oil and sunflower oil were tested by using alkali KH and solid KF/Al2O3 catalyst. Some properties of biodiesel were also compared with petroleum diesel. Freezing point, flash point, free glycerine, kinematical viscosity, density, distillation temperature was measured. Fuel performance of biodiesel production based on the alkali catalyzed and heterogeneous catalyzed was compared and discussed in detail. [1] Boz, N., Kara, M., “Solid base catalyzed transesterification of Canola oil” Chemical Engineering Communications (SOMER Special Issue, 2008, accepted, in press).


69

P39

Propylene epoxidation: High-throughput screening of silica and alumina supported silver and copper catalysts combinatorially prepared by

rapid sol-jel method

Işık Önal, Derya Düzenli, Anusorn Seubsai*, Michael Kahn*, Erol Şeker**, Selim Senkan*

Middle East Technical University, Chemical Engineering Department, Ankara, Turkey * University of California Los Angeles, California, USA

** İzmir Institute of Technology, Chem. Eng. Dept., Izmir, Turkey [email protected]

The objective of this work is to discover and develop novel, active and selective catalysts for direct epoxidation of propylene with oxygen by use of combinatorial catalyst preparation and testing techniques. Alumina and silica supported copper and silver catalysts were prepared using a single step sol-gel approach (i.e. metal salts were added during sol stage). Metal loadings were varied between 0 and 20 wt.% and also sol-gel synthesis parameters, such as ethanol and water amounts, were changed to prepare catalysts with varying surface areas and pore sizes. All the catalysts were synthesized with a combinatorial synthesis setup. The effects of metal loading, support type, surface area and pore size on propylene conversion and selectivity to propylene oxide (PO) were examined using a 20 array channeled high throughput microreactor under a feed stream containing 14% propylene, 26% oxygen in helium at 300 oC and a space velocity of 20 000 h-1. Data analysis was carried out by Micro-GC (CP-4900) equipped with a thermal conductivity detector (TCD) with deactivated capillary column. Among all the catalysts, silica supported copper catalyst showed the highest activity and selectivity. The highest PO yield was obtained as 0.58% for 0.5% Cu/SiO2 catalyst synthesized at 20 molar ratio of solvent/alkoxide. In the silica supported silver catalysts both propylene conversion and selectivity to PO increase with increasing metal amount. However, for copper containing silica catalysts, an increase in the metal amount caused a decrease in the PO yield. In order to explain metal loading effect, we examined some of fresh catalysts with XPS. It seems that copper in 0.5%Cu/SiO2 catalyst was isolated-like ionic rather than metal or metal oxide but in 9% Cu/SiO2 catalyst, copper was present in metallic and oxide forms. It could be concluded that isolated-like ionic Cu phase seems to be an active site for high PO selectivity. For Ag/SiO2 catalysts, Ag was found to be in metallic form regardless of silver loading and the intensity of Ag 3d5/2 peak increased with increasing the metal amount. The catalytic performance of catalyst also depends on support type and alumina supported catalyst candidates showed lower catalytic performances for both metals in our study. Some of the catalysts were prepared with the incipient wetness method in order to investigate the effect of preparation method on the catalytic activity. For Cu/SiO2 catalysts prepared with sol-gel method, PO yield decreased with increasing metal amount, but for the incipient wetness method an increase in metal amount didn’t change PO yield significantly.


70

P40 FT-IR Spectroscopic Study of Triethyl Phosphate Adsorbed on 3a and 4a Zeolites

Belgin Bardakçı, Neslihan Kaya*

Mehmet Akif Ersoy University,Faculty of Arts and Sciences, Physics Department,Burdur, Turkey * Süleyman Demirel University,Experimental and Observational Research and Application Centre,

Isparta, Turkey [email protected]

Zeolites are one of the most important groups of minerals uses in industry, described as hydrous alumina silicates of alkaline earth alkaline metals. Application of zeolite in many industrial areas has appeared as a result of their ion exchange properties catalytic properties, dehydration properties and ability to absorb molecules smaller than their own channel radius. In this work, the absorption of triethyl phosphate (TEP) on the 3A and 4A zeolites has been studied by using infrared spectroscopy. Their FT-IR spectra are reported in the 4000-400 cm-1 region. All the vibration modes of TEP are characterized.


71

P41

Comparative study of selective CO oxidation over Pt-Co-M/Al2O3 catalysts (M=Ce, Mg, Mn, Zr, Fe) in hydrogen-rich streams: Effects of second promoter

K. Erdem Uğuz, Ramazan Yıldırım


[email protected]

In this study, the selective CO oxidation over Pt-Co/Al2O3 catalyst in hydrogen rich streams was studied in the presence of Ce, Mg, Mn, Ze and Fe as the second promoters. The catalysts were prepared using incipient to wetness impregnation technique, and tested in a microflow reaction system. The effects of the second promoter type, Pt content of the catalyst, the reaction temperature, and CO2 and H2O concentrations of in the feed were investigated. It was found that the addition of a second promoter had no or negative effects on the CO conversion over 1.4 wt% Pt containing catalyst at 80 ˚C in the absence of CO2 and H2O. At 110 ˚C, however, the catalytic activity increased with the addition of all promoters resulting 100% in all cases while Pt-Co/Al2O3 catalyst had 96-98% CO conversion. Changing the Pt ratio from 1.4 wt% to 0.7wt% at 110 ˚C did not have any significant effects on Ce, Mg or Mn containing catalysts, and it has negative effects in the case of Fe and Zr. The CO conversion decreased over all the catalysts in the presence of 25% CO2 in the feed, and recovered fully or significantly with the addition of 10 % H2O depending on the promoter type. The increase of reaction temperature to 130 ˚C decreased the CO conversion in all catalysts. As a result, the addition of a Ce, Mg and Mn as the second promoter improved the CO conversion in some degree while Fe and Zr had negative effects on the catalytic activity of Pt-Co/Al2O3.


72

P42

Enzyme Immobilization on Gold Modified Thin Film Surfaces

Zeynep Eker, Merve Çınar, Gürkan Karakaş, Ufuk Bakır

Department of Chemical Engineering, Middle East Technical University, 06531, Ankara, Turkey [email protected], [email protected]

In order to produce a biosensor, immobilization of enzymes onto coated surfaces as biological sensing elements is an effective way. In this study, experiments on surface modification of bare glass with AuNPs/SiO2 and enzyme immobilization on these surfaces have been conducted. The methodology was to coat substrates with silica host matrix which is then functionalized with gold nanoparticles (AuNPs) and then to immobilize enzyme on this Au/SiO2 modified surface with a thiolamine cross-linker. Sol-gel was used to form porous SiO2 thin film and AuNPs deposition was done by dipcoating. As a model enzyme, invertase was immobilized on thin film with cysteamine cross-linker. The degree of enzyme immobilization and activity were determined by following enzymatic reactions spectrophotometrically.


73

P43

Photocatalytic Activity of Titania–Silica Mixed Oxides Prepared with co-Hydrolyzation in Acidic and Basic Media

Bilal Bayram, Alp Yürüm, Gürkan Karakaş

Department of Chemical Engineering, Middle East Technical University, Ankara, 06531, Turkey [email protected]

TiO2 in anatase form is suitable as catalyst and the most widely studied material for photocatalytic reactions. However the lack of porosity, small surface area, and the formation of dense layers in thin films are the major problems of bulk catalysts with limited photocatalytic activity and photon efficiencies. Utilization of oxide support materials with sufficient transparency within band gap range of TiO2 such as silica is one solution route on the development of efficient photocatalysts under solar irradiation. In the present study, simultaneous acidic or basic co-hydrolyzation of Tetraethyl orthosilacate (TEOS), Titanium tetrabutaoxide (TBOT) precursors were carried out in the presence of acidic and basic hydrolysis catalysts. Produced catalysts were subjected to calcination at 500oC. XRD pattern of produced catalysts showed that titania is in anatase phase. Surface area and average particle size of the catalyst will be analyzed by BET and SEM, respectively. Photocatalytic activities of produced mixed oxide catalysts were tested by photodegradation of phenol (100ppm) in aqueous media.


74

P44

Cellobiose Hydrolysis using Sulfated Zirconia Doped SBA-15 type Mesoporous Silica

Başak Cinlar, Volkan Değirmenci*, Ayşen Yılmaz**, Brent Shanks, Deniz Üner*

Chemical & Biological Eng., Iowa State University, Ames, Iowa, USA * Chemical Eng., Middle East Technical University, Ankara, Turkey

** Chemistry Department, Middle East Technical University, Ankara, Turkey [email protected]

Cellulose hydrolysis to glucose is a key step in the production of fuels and chemicals during the transition from a petroleum based economy to a bio-based economy. The hydrolysis of cellobiose can be used as an initial model for cellulose hydrolysis. In our previous work with organic Bronsted acids, the cellobiose hydrolysis rate was found to be proportional to the number of hydrated protons, which depend on the surface proton density and the acidic strength of the functional group. Good activity was found with propylsulfonic acid on SBA-15 structures (1). In this work, our objective was to test the activity and selectivity of the 15 mol% and 25 mol% zirconia and sulfated zirconia embedded in SBA-15 mesoporous frameworks. The characterization of the sulfated zirconia with 1H MAS NMR spectroscopy revealed intense peaks ca. 8 ppm, indicating strong Bronsted acidity. Lewis acid centers were also identified by FTIR of adsorbed CO, which were lost upon sulfation. High conversions in cellobiose hydrolysis reaction were observed with both sulfated and non-sulfated catalysts. Glucose degradation was found to occur at very significant rates, especially over sulfated catalysts. Experiments are in progress towards determining the conditions for maximizing the yield to the monosaccharide. (1) J.A. Bootsma and B. H. Shanks, Appl. Catal. A. Gen. 327(2007) 44.


75

P45 Comparative study of preferential CO oxidation over monolithic and particulate

Pt-Co-CeO2-Al2O3 catalysts

Yasemin A. Döker, Sadi T. Tezcanlı, Ramazan Yıldırım, Z. İlsen Önsan

Department of Chemical Engineering, Boğaziçi University, Bebek 34342, Istanbul, Turkey [email protected]

Preferential CO oxidation was studied over monolithic and particulate Pt-Co-CeO2-Al2O3 catalysts in hydrogen-rich environment. Monolithic catalysts were prepared by applying a layer of alumina support on to the walls of a cordierite monolithic carrier, referred to as wash-coating, and then impregnating active components. In this comparative study, the monoliths were wash-coated with alumina using three different methods, namely, colloidal coating, slurry coating and aluminum nitrate coating. Metal precursor solutions containing equivalents of 1.4wt% Pt, 1.25wt% Co and 1.25wt% Ce were impregnated over alumina wash-coated monoliths. Catalyst compositions were determined by atomic absorption spectrometry, while total surface area measurements, environmental scanning electron microscopy (ESEM) and polarizing optical microscopy were employed to physically characterize the catalysts prepared. The most promising monolithic catalyst preparation method was determined to be colloidal coating. Colloidal alumina coated and Pt-Co-Ce impregnated monolithic catalysts were tested for the preferential CO oxidation reaction in a micro-reactor flow system under a total flow of 100 cm3 min–1 using reaction temperatures in the 383-443 K range and typical feed compositions. Monolithic catalyst was found to exhibit the highest catalytic activity towards CO oxidation approaching 100% CO conversion at a temperature of 443 K in feed containing 1 vol% CO, 1 vol% O2 and 60vol% H2 with balance He, as compared to the 100% CO conversion on particulate Pt-Co-CeO2-Al2O3 obtained at 353 K using the same feed composition; the major reason for this difference was the difficulty of impregnating targeted quantities of metals on to the alumina washcoat of the monolith structure. Keywords: Pt-Co-CeO2/Al2O3, monolithic catalysts, wash-coating, preferential CO oxidation


76

P46

Preferential CO oxidation over promoted Au/γ-Al2O3 catalysts

Sadi T. Tezcanlı, Ramazan Yıldırım


Selective CO oxidation over Au/γ-Al2O3 catalyst modified with various metal oxide promoters (such as Mg, Mn, Fe, Ni, Ce, Co) was studied in hydrogen-rich environment. All Au based catalysts contained 1 wt% Au and 1.25 wt% promoter on Al2O3 as support. The catalysts were prepared using the impregnation of metal oxides to γ-Al2O3 support followed by the homogeneous deposition precipitation of gold over composite MOx/γ-Al2O3 support and tested in a microflow reaction system both in absence and presence of H2O and O2. The temperature programmed oxidation technique was performed in order to investigate the activity of catalyst in the temperature range of 80-150 oC. Contrary to Au/γ-Al2O3 catalyst, the metal oxide promoted (especially MnOx and MgO) Au/MOx/γ-Al2O3 exhibited high catalytic activity towards CO. It was found that the negative effect of CO2 was balanced by the addition of H2O significantly, and Au/MgO/γ-Al2O3 catalyst showed the best performance in the presence of a realistic amount of H2O and CO2 in the feed. Keywords: Preferential CO oxidation, Au/γ-Al2O3, promoter effect


77

P47

Water-Gas Shift Reaction over Bimetallic Pt-Ni/Al2O3 Catalysts

Burcu Selen Çağlayan, A. Erhan Aksoylu


Industrially well-known water gas shift (WGS) reaction is used for CO reduction in fuel processors which convert hydrocarbon fuels into hydrogen-rich gas streams to be sent to fuel cells with residual carbon monoxide levels of 10 ppm. Since the reaction is exothermic, reversible, equilibrium-limited and the desired CO levels can be achieved at low temperatures, it is normally performed in two steps. In the first step a high-temperature shift (HTS) catalyst is used for reaction at 340–530oC. The second step is performed on a low temperature shift (LTS) catalyst at 180–230oC. WGS catalysts for fuel cell applications should be active, thermally stable, resistant to poisoning and highly selective for a wide range of H2O/CO ratios. The fact that conventional high temperature (Fe–Cr oxide) and low temperature (Cu–Zn–Al2O3) WGS catalysts cannot be used in fuel cell applications has led to interest in the development of catalyst formulations which are based on noble metals supported on metal oxide carriers. Among the noble metals studied, Pt has found to be highly active and Al2O3 is a very high surface area support, which has been reported to result in significant enhancement of activity, selectivity and stability of dispersed noble metals for a number of catalytic reactions. In the present study, water-gas shift reaction was studied on a series of Pt-Ni/Al2O3 catalysts for medium temperature shift reaction (200–450oC). Bimetallic catalysts with different Ni/Pt ratios were prepared by sequential impregnation method and they were characterized by x-ray spectroscopy, scanning electron microscopy and back scattering electron imaging. The effects of the Ni content, GHSV and H2O/CO ratio on the WGS activity of the catalysts were investigated. The inhibition effect of CO2 and H2 in the feed was also studied aiming to understand the performance characteristics of the catalysts for the feed compositions similar to reformer effluent of a typical fuel processor. CO conversions levels were found to increase with increasing Ni/Pt ratio and increasing H2O/CO ratio in the feed. The studies revealed that the bimetallic Pt-Ni/Al2O3 catalysts are very active, selective and stable for WGS reaction. Since the Pt-Ni bimetallic system had been proven to be high performance autothermal reforming catalysts, the current results show that those catalysts can be a good candidate to be used in the first two stages of a fuel processor. Since the catalysts are highly active, i.e., the CO conversion levels are near equilibrium values, through the mid-temperature region of low temperature and high temperature water-gas shift reaction, the necessity of two-stage WGS in fuel processor can be eliminated.


78

P48

The effect of Ni:Pt ratio on autothermal reforming performance of Pt-Ni/δ-Al2O3 catalyst

Feyza Gökaliler, Bayram A. Göçmen, A. Erhan Aksoylu


[email protected]

The bimetallic catalyst, 0.2wtPt-15wtNi/δ-Al2O3, was taken as the reference and the Pt and Ni loadings were changed in an experimentally designed fashion to understand the effect of Pt:Ni ratio on the H2 production activity and the H2/CO selectivity - which reflects the secondary WGS activity of the catalyst. The test runs were conducted at 623- 743 K range. In the tests, C/O2 and W/F are used as the reaction parameters. The detailed studies indicated that (i) the bimetallic system is superior to the monometallic catalysts used in ATR, (ii) the secondary WGS activity of Pt-Ni system as well as its operation temperature, ca. 670 K, makes it possible to perform ATR-HTS reactions in a single unit when a combined optimization of Pt:Ni ratio of the catalyst and reaction parameters is made.


79

P49

Performance analysis for 2-propanol and direct methanol fuel cells based on Pt containing anode electrocatalysts

N. Alper Tapan, Ezgi Öztürk


[email protected]

Direct 2-propanol and methanol fuel cell performances based on Pt containing anode electrocatalysts has been evaluated. Parameter estimation was performed by non-linear least squares method using Levenberg Marquardt algorithm. Cell performance, open circuit voltage, maximum current density, maximum power density were measured at various alcohol concentrations and cell temperatures. 2-propanol fuel cell shows the highest performance at 1M concentration and 80oC operating temperature. The highest practical efficiency (at the maximum power density) was found as 38% at 2M 2-propanol concentration and 60°C operating temperature. Cross-over current was minimum for 0.5 M 2-propanol concentration at 40oC operating temperature. According to the parametric analysis, it seems that 2-propanol fuel cells can work at lower temperatures than methanol fuel cells at optimum operating conditions.


80

P50

IMPROVING THE PHOTOCATALYTIC ACTIVITY OF TiO2 BY PHOTON UP-CONVERSION

D.Doğu, B. Korkmaz Erdural*, G. Karakaş*

Middle East Technical University, Micro and Nanotechnology Programme, 06531, Ankara * Middle East Technical University, Chemical Engineering Department, 06531, Ankara

[email protected] TiO2 photocatalysts with anatase structure generate strong oxidizing power under UV irradiation with a wavelength less than its corresponding band gap energy. The absorption of photon with sufficient energy results with the generation of hole (h+) and electron (e-) pair which react with H2O and O2 over the surface and hydroxyl radicals (OH-). As a result of these surface reactions, super oxide ions (●O2-) are generated, which are very active on the decomposition and mineralization of organic compounds. However the efficiency of TiO2 is limited and only 12% photon efficiency can be obtained under idealized laboratory conditions because of the limited spectral band of the solar irradiation which has higher energy than the band gap is utilized. One way to improve the photocatalytic efficiency is the harvesting the photons having less energy than the band gap of semiconductor by metal dopants. The other technique is the photon up-conversion where a metal ions are used to combine the energies of two photons with lower energy (in visible spectrum) and emit a photon with higher energy (in UV band ). By photon up-conversion, a visible light can be transposed into a UV-light. Praseodimyum (Pr) is a good photon up-conversion material which was studied for laser and waveguides in literature. In this study, sol-gel method was used to produce Pr doped titania and dip coating method was applied to obtain thin films over galss and quartz samples. Photocatalytic activities of the thin films were characterised against the degredation of methylene blue stains. The complete degradation of methylene blue was observed by Pr doped TiO2/SiO2 thin films under artificial irradiation source at the end of 24 hours, whereas, by use of undoped TiO2/SiO2 some of methylene blue remained partially undegregated. Photoluminescence spectra of TiO2 and Pr doped TiO2 were examined. Pr doped TiO2 shows a peak at around 600nm that causes photon up-conversion process. The surface morphology of the coated substrates were investigated by atomic force microscopy.

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