BORESKOV INSTITUTE OF CATALYSISSiberian Branch, Russian Academy of Sciences

Prof. Dr. Valerii I. Bukhtiyarov

Tel.: +7-(383)-330-67-71Fax: +7-(383)- 308-356E-mail: vib@catalysis.ru

Pr.Akademika Lavrentieva, 5Novosibirsk, 630090Russia

CATALYSTS WITH NANOSTRUCTURED ACTIVE COMPONENT.

Synthesis, Investigation And Application in Processes of Environmental Protection,

Power Production and Refinery

Reduction of the size parameters of a substance to nanometer scale causes

appearance of unique properties which can be used in practice for development of novel

materials and technologiescalled as NANOMATERIALS and

NANOTECHNOLOGIES Not only physical properties, but also

reactivity of a substance in nanometer scale will be

changed.As consequence, new functional

nanomaterials such as chemical sensors, CATALYSTS, adsorbents, membranes, fillers

can be produced

Nanomaterials and Catalysis

Nanomaterials and CatalysisSize effects are known since the Boudart’s discovery of the structure-sensitive

and structure-insensitive reactions and have been studied for a long time

1.Bukhtiyarov V.I. Chemical Reactivity of Metal Clusters at Solid Surfaces, In: Interfacial Science, “Chemistry for the 21st Century” Monograph (Ed. M.W.Roberts), Blackwell Science, 1997, 109-128.

2.Bukhtiyarov V.I., Slinko M.G. Metallic nanosystems in catalysis. Russian Chemical Reviews, 2001, v. 70, n.2, 147-159.

3 10 100 1000

Particle Size, Å

Tu

rno

ver

num

ber

, s-1

Positive size effects

Structural insensitive reaction

Structural sensitive reactions

• Abatement of СО and CHx

• Reforming of gasoline• Hydrogenation of unsaturated

CxHy

• Hydrogen and methanol FC ….

Systematic investigation of the size effects in catalysis by metallic nanoparticles and, especially, their application in practice require:

1) to develop the methods of synthesis of nanosized metallic particles, which have to provide:

Homogeneous size distribution with the mean particle size which is optimal for catalytic properties;

Stability of the supported metallic particles against sintering; Economical practicability

2) to develop the methods of testing of catalytic properties:

with application of porous and planar supports; intensification of catalytic activity testing – the search of structure-

sensitive reactions using the testing protocols developed by catalysts producers

Nanomaterials and Catalysts

It has been shown that variation of pH and gas-phase composition during ageing of the solution of Pt metal precursor regulates the sizes of polynuclear platinum hydroxocompomlexes:

[Pt(OH)6]2- + nH+Pt

O

OH

O

O

H H

H

Pt

OH

O

H

Pt

OH

O

H

Pt

OH

O

H

[Pt(-OH)m]y

0.8-1.2 nm2.0-2.4 nmThis provides homogeneous size distribution of [Pt(OH)m]y collodidal particles

in impregnated solution (contrary to commercial solutions): SAXS data

0 2 4 6 8 10 12 14 16 18 20 22 24 26 280

20

40

60

80

100

Dv(

d)

dPt

, nm0 1 2 3 4 5 6 7 8 9 10

0

20

40

60

80

100

dPt, nm

Dv

(d)

0 1 2 3 4 5 6 7 8 9 100

20

40

60

80

100

dPt

, nmD

v(d

)

Commercial solutionCommercial solution Our solution (lower pH)Our solution (lower pH) Our solution (higher pH)Our solution (higher pH)

Preparation of supported metal nanoparticles with Preparation of supported metal nanoparticles with homogeneous size distribution. Colloid formationhomogeneous size distribution. Colloid formation

Scientific bases of preparation of platinum nanoparticles with the mean sizes of 0.5–10 nm on -alumina have been developed

Size effectsSize effects inin catalysis by metal nanoparticlescatalysis by metal nanoparticles. . Observation and investigationObservation and investigation

Application of the prepared solutions for impregnation of alumina allows us to prepare the series of Pt/-Al2O3 catalysts and shows the size effect in CH4 oxidation

0 2 4 6 8 100

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35 400

10

20

30

40

50

d, nm d, nm

Nd/N

tota

l1

00

, %

Nd/N

tota

l1

00

, %

Tcalcination = 400оС Tcalcination = 600оС

TEM images and Pt particle size TEM images and Pt particle size distribution for the Pt/distribution for the Pt/-Al-Al22OO33

catalysts with smallest platinum catalysts with smallest platinum nanoparticesnanopartices

TEM images and Pt particle size TEM images and Pt particle size distribution for the Pt/distribution for the Pt/-Al-Al22OO33

catalysts with smallest platinum catalysts with smallest platinum nanoparticesnanopartices

- TOF or turn-over frequency is rate of a catalytic reaction, normalized to the number of surface atoms of active compoment

TO

F, s

ec-1

0 2 4 6 8 10

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Size effect in methane Size effect in methane oxidationoxidation

<d>, nm

Preparation of supported metal nanoparticles Preparation of supported metal nanoparticles with homogeneous size distribution. Epitaxial growthwith homogeneous size distribution. Epitaxial growth

Scientific bases of preparation of gold nanoparticles with the mean sizes of 1–10 nm on high-surface aluminas have been developed

Au [111] faceAu

OAlAl2O3 [111]

face

x 600 000

HRTEMHRTEM images ofimages of gold nanoparticlesgold nanoparticles onon AlAl22OO33The modelThe model ( (molecular dynamics methodmolecular dynamics method)) of of

epitaxialepitaxial growth of gold nanoparticles on Algrowth of gold nanoparticles on Al22OO33

results in epitaxial growth of gold nanoparticles, that provides the best results in preparation of the particles with homogeneous size distribution

and improved stability against sintering

[AuCl4]-

+ Al2O3

+ NaOH Au(OH)3·[AuCl4-n(OH)n]-/MOx

Al 2O3

Aumetal

O2

It has been shown, that «deposition-presipitation»:

Size effectsSize effects inin catalysis by metal nanoparticlescatalysis by metal nanoparticles. . Observation and investigationObservation and investigation

We have observed the size effect in reaction of low-temperature CO oxidation over Au/Al2O3 catalysts, which is appeared as sharp increase of TOF for the gold

supported particles with the mean sizes of 1-2 nm

0 5 10 15 20 250

20

40

60

80

100

120

140

TO

F (

sec-1

)10

-4

dvs(nm)

0 2 4 6 8 10 12 14 16 18 200

50

100

150

Dl = 1.8 nm

Dvs

= 2.0 nm

Th

e p

art

icle

nu

mb

er

Particle size, nm

Size distribution of Au nanoparticles

TEMTEM imagesimages

Flow reactorТ = 293 K; 0.05%CO, 2% of H2O, air for balance

We have shown the perspectives of application of the catalysts – gold nanoparticles supported on alumina – to solve the «cold start» problem for car engines

Catalysts on the bases of metallic nanoparticlesCatalysts on the bases of metallic nanoparticles for for afterburning afterburning

of exhaust gases from car enginesof exhaust gases from car engines

standard neutralization of standard neutralization of

exhaust gases (from CHexhaust gases (from CHxx and and

CO at high temperatures)CO at high temperatures), ,

while the deeper layerwhile the deeper layer ( (Au) Au)

burns up CO on cold engineburns up CO on cold engine..

Au/AlAu/Al22OO33

Pt/AlPt/Al22OO33

(commercial)(commercial)

5050 100100 150150 250250 30030020020000

2020

4040

6060

8080

100100

1 run 2 run 3 run

Temperature, Temperature, 00CC

CO

co

nve

rsio

n,

CO

co

nve

rsio

n, %%

The method of preparationThe method of preparation of honeycomb of honeycomb

catalystscatalysts for afterburning of exhaust gases for afterburning of exhaust gases

from car enginesfrom car engines, ,

front layer of whichfront layer of which ( (Pt) providesPt) provides

Observation andObservation and study of the nature of the size effectsstudy of the nature of the size effects in practically important in practically important catalytic reactionscatalytic reactions with further development and scaling-up of more effective with further development and scaling-up of more effective

((nanonano-)-)catalystscatalysts withwith lower loading of the noble metalslower loading of the noble metals

Preparation of supported metal nanoparticles Preparation of supported metal nanoparticles with homogeneous size distribution.Epitaxial growthwith homogeneous size distribution.Epitaxial growth

HRTEM study of Pd+Rh/Al2O3+CeO2-ZrO2 automobile catalyst produced by UECPallowed us to identify epitaxial growth of Pd particels on ceria-containing phase

Preparation of supported metal nanoparticles Preparation of supported metal nanoparticles with homogeneous size distribution. MMM as with homogeneous size distribution. MMM as

supportssupportsHomogeneous distribution of Ag nanoparticles have been reached with application of

mesophase mesoporous silica (SBA-15) – data of DICP CAS and FHI der MPG

There is a possibility to vary fluently the pore sizes of these There is a possibility to vary fluently the pore sizes of these materials materials ((silicasilica, , carboncarbon) ) via variation of the preparation via variation of the preparation conditionsconditions

Internal location of metal particles allows limitation of the Internal location of metal particles allows limitation of the particle sizes by pore diametersparticle sizes by pore diameters

Nanomaterials and Catalysis

4) to elucidate the reasons of unique catalytic properties of nanoparticles and search of the ways for the their practical applications

Systematic investigation of the size effects in catalysis by metallic nanoparticles and, especially, their application in practice require:

3) to develop the physical methods for characterization of supported metallic nanoparticles:

Transmission electron microscopy with high resolution (HR TEM) Scanning electron (SEM) and probe microscopy (STM, AFM) X-ray absorption and scattering (EXAFS, XANES, SAXS) Surface Science methods for in situ measurement (IRAS, SFG, UV-Vis,

XPS, XAS)

Combined application of Combined application of in-situin-situ XPS and MS for XPS and MS for operando study of operating nanostructured operando study of operating nanostructured

catalystscatalysts

LensesX-raytubes

Sample holder

sample

0

2

4

6

0 200 400 600 800 1000

Kinetic energy of photoelectrons (eV)T

he

mea

n f

ree

pat

h o

f p

ho

toel

ectr

on

s (t

orr

×m

m)

Gas cell

Bukhtiyarov V.I., Kaichev V.V., Prosvirin I.P. X-ray Photoelectron Spectroscopy as a Tool for In situ Study of the Mechanisms of Heterogeneous Catalytic Reactions. Topics in Catalysis 32 (2005) 3-15

Photoelectrons (Еkin = h – Eb)

X-rays

To perform in-situ XPS measurements, it is necessary:

to decrease the path of photoelectrons in high-pressure zone;

to provide the differential pumping of X-ray source and energy analyzer.

VG photoelectron spectrometer has been reconstructed for operando measurements in millibar pressure range

68 72 76 80 84

68 72 76 80 84

Pt4f + Al2p

PtO2

Ptmet

Binding energy, eV

Binding energy, eV

Inte

nsi

ty,

arb

.un

.

Inte

nsi

ty,

arb

.un

.

Pt4f + Al2pPt+

Binding energy, eV

P(CH4) = 0.02; P(O2) = 0.04 mbarT = 430oC

68 72 76 80 84

Combined application of Combined application of in-situin-situ XPS and MS for XPS and MS for operando study of operating nanostructured operando study of operating nanostructured

catalystscatalystsUsing this spectrometer, the chemical state of platinum nanoparticles

in Pt/Al2O3 catalysts for total oxidation of methane were studied

Investigation of the nature of active sites in Investigation of the nature of active sites in nanostructured catalysts with physical methods nanostructured catalysts with physical methods

Identification of active sites in Au/Al2O3 catalysts for low-temperature CO oxidation: XRD and UV-VIS spectroscopy for

10000 20000 30000 40000 50000 600000

1

2

3

4

Wavenumber, cm-1

0.13%

0.05%

0.02%F

(R)

10000 30000 5000020000 40000 60000

0.3%

Au, wt.%

Au

AuAu [Au-O-Au]m

Al2O3

500oC

Au/Al2O3

800oC

600oC

72 74 76 78 80 82 84

Au [2.2.2.]

Au [3.1.1.]

2

0 50 100 150 200 2500

20

40

60

80

100

H2O on

H2O off

H2O on

Time-on-stream (min)

CО

co

nve

rsio

n (

%)

The influence of water on the The influence of water on the activity of gold in CO oxidationactivity of gold in CO oxidation

Investigation of the nature of active sites in Investigation of the nature of active sites in nanostructured catalysts with physical methods nanostructured catalysts with physical methods

Suggestion about the nature of active sites and experiments about influence

of water is in agreement with the proposed mechanism of this reactionThe proposed mechanism of The proposed mechanism of

CO oxidation over gold CO oxidation over gold nanoparticlesnanoparticles

M.C. Kung, R.J. Davis, H.H. Kung

J. Phys. Chem. C: 111 (2007) 11767

CATALYSISCATALYSIS

Industrial catalysis has involved nanoparticles since beginning of the 20-th century

NANOSCIENCENANOSCIENCE

Addition of the “nano” prefix to many technical terms is not simple replacement of the unit of Ångstroms

Nanoscience gives a great contribution

to a fundamental approach for optimization of the catalyst performance

Nanomaterials and catalysis

Scientific basesScientific bases of the preparation of nanocompositeof the preparation of nanocomposite (Со)(Со)MoSMoS22 phase phase supported on aluminasupported on alumina

Methodology of synthesis of the mixed Со-Мо sulfide phase with high dispersity and location of cobalt ions on the lateral phase of the layered MoS2 phase

has been developed and realized

Preparation of the support (Al2O3) with optimal texture

properties and its impregnation with Co-Mo

solutions

Preparation of impregnating solutions with bimetallic Co-

Mo compounds

Preparation of bimetallic Co-Mo compound

in oxide form of the catalysts

Catalysts with active component in sulfide form

Synthesis of the proposed Synthesis of the proposed structurestructure of active sites in of active sites in hydrodesulfurization catalysts:hydrodesulfurization catalysts:

Со

S

Mo

Co-MoS2

Preparation and physical-chemical characterization of the catalysts

All steps of the catalyst preparation have been studied with a number of physical methods: NMR, EXAFS, IR-spectroscopy, HRTEM

DBT

4-МMDBT 4,6-DMDBT

3200С406 ppmS

3400C54 ppmS

3600C14 ppmS

Testingthe catalytic properties

Optimization of the catalyst working conditions

Study of catalytic properties ofStudy of catalytic properties of Со- Со-Mo-S/AlMo-S/Al22OO33

catalystscatalysts in hydrodesulfurization ofin hydrodesulfurization of diesel fractiondiesel fraction

Systematic investigation of catalytic activity of Со-Мо sulfide catalysts in hydrogenolysis of С-S bond have been performed depending on the support nature and sulfidation conditions of oxide precursors

The catalytic data were used to optimize the conditions ofThe catalytic data were used to optimize the conditions of catalyst activationcatalyst activation ( (sulfidationsulfidation) ) andand operationoperation, , as well as the proceduresas well as the procedures of active component supporting on specific types of alumina oxidesof active component supporting on specific types of alumina oxides,, prepared by the companyprepared by the company ( (JSCJSC “Industrial catalysts”“Industrial catalysts”), ), production facilities of which have being production facilities of which have being

apply for apply for industrial productionindustrial production of the catalystsof the catalysts

To test the catalytic performance of the synthesized samples, To test the catalytic performance of the synthesized samples, technological set-up for performing the catalytic testing under the technological set-up for performing the catalytic testing under the representative conditionsrepresentative conditions andand unique (for Russia) analytical unit unique (for Russia) analytical unit allowing not onlyallowing not only definition of total content of the residual sulfurdefinition of total content of the residual sulfur, , but alsobut also identification of individual sulfur-containing compounds identification of individual sulfur-containing compounds

have been created at the Boreskov Institute of Catalysishave been created at the Boreskov Institute of Catalysis

• StudyStudy of interaction ofof interaction of individualindividual (first of all, very stable)(first of all, very stable) sulfur-sulfur-containingcontaining organic compounds with new series of sulfide catalystsorganic compounds with new series of sulfide catalysts..

• Optimization of the methods and conditions for sulfidation Optimization of the methods and conditions for sulfidation of active of active componentcomponent ..

• Development of the hydrodesulfurization catalysts of diesel fraction Development of the hydrodesulfurization catalysts of diesel fraction to sulfur content in several ppmto sulfur content in several ppm..

NanocompositeNanocomposite of Co-Mo sulfide catalystsof Co-Mo sulfide catalysts for deep hydrotreating of straight-run gas-oil for deep hydrotreating of straight-run gas-oil

Industrial testing of pilot batch (30 tons)* of nanocomposite catalysts in hydrotreating reactor on Saratov oil-refinery plant decreases the sulfur content

from S < 1800 ppm to S < 50 ppm (Euro-4 standard)

Independent expertise of the catalytic properties of the synthesized catalyst in comparison with imported catalysts

0

100

200

300

400

500

0 5 10 15 20 25 30 35 40

Pro

du

ct s

ulp

hu

r (p

pm

wt)

Scaling up of the catalyst production

- preparation of pilot batch of the catalysts were performed by JSC “Industrial catalysts”

Siberian Branch of RAS: interdisciplinary project №79 «Size effects in catalysis by metals. Development of preparation methods and study of nano-sized metallic particles»Russian Ministry of Education and Science: state contract 2007-3-1.3-28-03-127 «Development of technological bases of application of nanosize effects to produce nanostructured catalysts of new generation»

Russian Foundation for Basic Researchproject # 08-03-01016 “The influence of the size effects on activity of Pt nanoparticles in various heterogeneous catalytic reaction”

Russian Foundation for Basic Research (joint Call with China)project # 07-03-92117-GFEN “Size effects in adsorption and catalysis over metals: from individual atoms and nanoparticles to nanostructured catalysts»

Acknowledgement for financial support