microkineticmodels for exhaust-gas after-treatment€¦ · isothermal flat bed reactor: spatially...

KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association

Institute for Chemical Technology and Polymer Chemistry (ITCP)

www.kit.edu

Institute for Catalysis Research and Technology (IKFT)

Microkinetic models for exhaust-gas after-treatment

Olaf Deutschmann, Karlsruhe Institute of Technology (KIT)

CLEERS 2015

Olaf Deutschmann

Institute for Chemical Technology and Polymer Chemistry2

THE CHALLENGE

Olaf Deutschmann


Catalytic converter: Physics and chemistry on many scales

Courtesy of J. Eberspächer GmbH& Co

Olaf Deutschmann


1 m10 s

1 mm10 ms

10 m 100 s10 nm1 nm0.1 nm

Catalytic converter:Physics and chemistry on many scales

Olaf Deutschmann


THE DREAM

Olaf Deutschmann


Simulation of catalytic reactors by multi-scale modeling:Information flux over the time and length scales

Complexity

Leng

thTi

me

Elementary reactions on surfaces

Particles and phases

Porous supports

Reactor behavior

DFT

kMC

Reactive flow

AdditivitySpill-over

Diffusion

Continuum mechanics

Transient models for heat and mass transfer

Multi componentParticle Sizes

Pt

Ce

Reactor behavior

Olaf Deutschmann


THE REALITY

Olaf Deutschmann


1 m10 s

1 mm10 ms

10 m 100 s10 nm1 nm0.1 nm

Catalytic converter:Physics and chemistry on many scales

Olaf Deutschmann


Density Functional Theory (DFT):Understanding catalysis on a molecular level

0.1 nmJ.A. Keith, J. Anton, T.Jacob. Chapter 1 in Modeling and Simulation of HeterogeneousCatalytic Reactions. O. Deutschmann (Ed.), 2011

Energy barriers

Understanding reaction paths

Pre-screening of catalysts

Olaf Deutschmann


Aging of Pd/Pt catalyst for CH4 total oxidation:Characterization by TEM and EDX

Total Pd/Pt loading 5:1

Most particles d < 5 nm Homogenous alloy

(Pd100Pt0 - Pd89±5Pt11±2)

Some particles d 10 nm Homogenous Alloy, higher Pt-content

Few large particles d > 30 nm Homogenous alloy High Pt content Formation of core-shell structure after

100 h, 1000 ppm CH4, 10% O2

A. T. Gremminger, H. W. Pereira de Carvalho, R. Popescu, J.-D. Grunwaldt, O. Deutschmann. Catalysis Today (2015) DOI 10.1016/j.cattod.2015.01.034

CH4 + 2 O2 CO2 + 2 H2OPd/Pt

0 10 20 300

20

40

60

80

100

Pt L

Con

cent

ratio

n (a

t. %

)

x (nm)

Pd L

Probe 13: Pd-Pt/Al2O3 aged (Sp. 8)

Olaf Deutschmann


Aging of Pd/Pt catalyst for CH4 total oxidation:Characterization by TEM and EDX

Total Pd/Pt loading 5:1

Most particles d < 5 nm Homogenous alloy

(Pd100Pt0 - Pd89±5Pt11±2)

Some particles d 10 nm Homogenous Alloy, higher Pt-content

Few large particles d > 30 nm Homogenous alloy High Pt content Formation of core-shell structure after

100 h, 1000 ppm CH4, 10% O2

A. T. Gremminger, H. W. Pereira de Carvalho, R. Popescu, J.-D. Grunwaldt, O. Deutschmann. Catalysis Today (2015) DOI 10.1016/j.cattod.2015.01.034

CH4 + 2 O2 CO2 + 2 H2OPd/Pt

3 nm shellPd52±4Pt48±2

22 nm corePd5±3Pt95±2

• Total NP compositionPd36±5Pt64±6

Olaf Deutschmann


Kinetic Monte Carlo Simulation of surface reactions and diffusion on catalytic particles: CO oxidation on Pt/Al2O3

1-100 nm Coverage over time on each facet

Reaction rates of each process

Number of times each process was used

L. Kunz et al., Chapter 4 in Modeling Heterogeneous Catalytic Reactions. O. Deutschmann (Ed.), 2011

Olaf Deutschmann


Effect of thermal aging on particle size distribution in DOC

Fresh DOC

DOC aged hydrothermally aging at 950°C

Particle size distribution

W. Boll, S. Tischer, O. Deutschmann, Ind. & Eng. Chem. Res. 49 (2010) 10303

Olaf Deutschmann


Catalytic converter: Physics and chemistry on many scales

1 m10 s

1 mm10 ms

10 m 100 s10 nm1 nm0.1 nm

Olaf Deutschmann


Modeling heterogeneous reactions: Concept of rate equations (mean-field approximation)

SR j

jk

ikijk

kcks

'

f

Surface reaction rate

ΓcΘ iii

Surface coverage

ΓMs

tΘ iii

Locally resolved reaction rates depending on gas-phase concentration and surface

coverages

O. Deutschmann. in Handbook of Heterogeneous Catalysis, 2nd Ed.,, G. Ertl, H. Knözinger, F. Schüth, J. Weitkamp (eds.), p. 1811, Wiley-VCH, 2008

Rate expression

s

1

expexpN

i

iiμi

aβkf RT

ΘεΘ

RTE

TAk kkikkk

= microscopic site density

Olaf Deutschmann


Surface reaction kinetics of CO oxidation on Pt/Al2O3 DOC: Mean field approximation

D. Chan, S. Tischer, J. Heck, C. Diehm, O. Deutschmann. Applied Catalysis B: Environmental 156–157 (2014) 153.

Reaction coordinate

En

erg

y [k

J/m

ol]

-600

-500

-400

-300

-200

-100 free Pt surfaceCO coveredO covered

CO+O2

CO(Pt)+O2

CO(Pt)+O2(Pt)

CO2(Pt)+O(Pt)

CO(Pt)+2 O(Pt)

CO2+O(Pt)

Olaf Deutschmann


D. Chatterjee, O. Deutschmann, J. Warnatz. Faraday Discuss. 119 (2001) 371J. Koop, O. Deutschmannn. Appl. Catal. B: Env. 91 (2009) 47

Proposed surface reaction mechanism for Pt/Rh-based three-way catalysts: Mean field approximation

Olaf Deutschmann


Thermodynamic consistency

Development of micro kinetic models for simulations of catalytic reactors

Surface ScienceExperimental

Surface ScienceTheoretical

Reaction mechanismand kinetics (idea)

Modeling of lab reactors(including gas phase kinetics and

transport models)

Sensitivity & reaction flow analyses

Lab experiments(conversion, selectivity,

ignition/extinction temperatures,spatial & temporal profiles,

coverage)

Comparison of experiment and

simulation

Revised reaction mechanism

Technical reactor

Olaf Deutschmann


Surface reaction rate is proportional

to the catalytic surface area

determined by CO-chemisorption

Pt particle sinteringAl2O3

Scaling factor:Scaling factor:

geocatcat

cat

geo

catgeocat AM

mDAAF

/

Modeling catalyst loading and dispersion:Variation of dispersion in a DOC due to aging

Pt particles

, cat/geo i s i i ij F M s

Ageo

Acat

AcatAgeoAcat

D. Chan, S. Tischer, J. Heck, C. Diehm, O. Deutschmann. Applied Catalysis B: Env. 156–157 (2014) 153.

C. Karakaya, O. Deutschmann. Appl. Catal. A: Gen. 445-446 (2012) 221

Olaf Deutschmann


Multi-scale modeling:From 10-10 m and 10-13 s to 1m and 10 s

1 m10 s

1 mm10 ms

10 m 100 s10 nm1 nm0.1 nm

Olaf Deutschmann


Coupling of surface reaction rate and flow field -Modeling internal transport limitation of reaction rate

i

ii Φ

Φ )tanh(

0,,eff

ii

ii cD

sLΦ

Effectiveness factor

Thiele Modulus

, c a t /g e o i s i i ij F M s

fluid

washcoat

R.E. Hayes, B. Liu, M. Votsmeier. Chem. Eng. Sci. 60 (2005) 2037.

Simple model: effectiveness factor Reaction-diffusion equations

Olaf Deutschmann



1 m10 s

1 mm10 ms

10 m 100 s10 nm1 nm0.1 nm

Olaf Deutschmann


Impact of models for channel shape and washcoatdiffusion on NO profiles in a DOC

NO profiles at lean conditions at 250°C (steady-state operation)CFD code: Fluent + DETCHEM N. Mladenov, J. Koop, S. Tischer, O. Deutschmann. Chem. Eng. Sci. 65 (2010) 812

no washcoatdiffusionlimitation

porousmediamodel

Olaf Deutschmann








coverage)


transport models)



simulation



Technical reactor

Olaf Deutschmann


Lab test benches in the Exhaust-Gas Center Karlsruhe: High-Pressure setup

Tests of catalyst coated honeycombs

(d = 2.54 cm, length < 6cm)

Labview automatic controlled measurements

Coated pipes, reactor and analytics – for sulfur

Gases: NO, NO2, H2O, CO…

Temperature: RT – 700°C

Pressure: 1- 5 bar

Flow: 10 - 70 slpm

Gas analytics: FTIR, (MS)

www.abgaszentrum-karlsruhe.de

Olaf Deutschmann


V. Schmeißer, J. Perez, U. Tuttlies, G. Eigenberger, Top. Catal. 42 (2007) 15

Isothermal flat bed reactor: Spatially and time-resolved exhaust-gas composition in catalyst channel

NO2 profile in NSC during storage

CO profile in DOC

J. Koop, O. Deutschmann. SAE 2007-01-1142.J. Koop, O. Deutschmann. Appl. Catal.B: Env. 91 (2009) 47

G. Eigenberger et al.

Olaf Deutschmann


Lab test bench SpaciPro:Invasive in-situ technique for axially resolved profiles

Tests of catalytically coated honeycombs (d = 2 - 2,54 cm,

length ~ 5 cm)

Axially resolved profiles of species concentration, gas-

phase and surface temperatures (resolution: 0.25 mm)

Gases: Gaseous and liquid HCs, CO,

CO2, NH3, NO, NO2, O2,

Air, N2, H2, H2O

Temperature: RT – 1000°C

Pressure: 1 atm

Flow: 0.5 - 5 slpm

Gas analytics: FT- IR, MS, GC


G. Fisher et al., 2006R. Horn, N. J. Degenstein, K. A. Williams, L. D. Schmidt, Catal. Lett. 110 (2006) 169.J. Sá, D.L. Abreu Fernandes, F. Aiouache, A. Goguet, C. Hardacre, D. Lundie, W. Naeem,

W.P. Partridge, C. Stere, Analyst 135 (2010) 2260.A. Donazzi, D. Livio, M. Maestri, A. Beretta, G. Groppi, E. Tronconi, P. Forzatti, Angew.

Chem. Int. Ed. 50 (2011) 3943.D. Livio, C. Diehm, A. Donazzi, A. Beretta, G. Groppi, O. Deutschmann, Appl. Catal. A

467 (2013) 530.

Olaf Deutschmann


NO LIF profile during reduction by H2 to NH3 in Pt/Al2O3one-side-coated single channel of a DOC

A. Zellner, R. Suntz, O. Deutschmann, Angew. Chem. Intl. Ed. 54 (2015) 2653.

Non-invasive in-situ analysis of spatial and temporal profiles of species concentration and temperature in the gas phase above a catalytic surface using Raman and LIF-spectroscopy

Lab test bench CATHLEN: Optical diagnostics of catalytic reactors

NO

Olaf Deutschmann








coverage)


transport models)



simulation



Technical reactor

Olaf Deutschmann


Effect of catalyst loading on conversion of CO in DOCReaction flow analysis


440 460 480 500 520 540

0 2 4 6 8 10

T 50

[K]

Pt dispersion [%]

exp.sim.

Olaf Deutschmann








coverage)


transport models)



simulation



Technical reactor

Olaf Deutschmann


Transient simulation of lab light-off experiment:Temporal variation of axial profiles during light-off


T = 508 K, Disp = 3%

0

0.2

0.4

0.6

0.8

1

400 450 500 550

CO

con

vers

ion

T [K]

exp.sim. eff.

sim. detailed

0

0.5

1

1.5

-3 0 3 6 9 12 15 18 21 24 27 30 6

7

8

9

CO [%

]

CO2 [

%]

z [mm]

CO exp.CO2 exp.

sim. eff.sim. detailed

z [mm]

CO(P

t)

5 10 15 20 250

0.2

0.4

0.6

0.8

t [min]

4367

z [mm]

CO2(P

t)

0 5 10 15 20 250

2E-07

4E-07

6E-07

8E-07

1E-06

1.2E-06

1.4E-06

t [min]50

4367

z [mm]

O(Pt

)

0 5 10 15 20 250

0.2

0.4

0.6

0.8

1

t [min]

50 4367

z [mm]

CO(P

t)

0 5 10 15 20 250

0.2

0.4

0.6

0.8

1

t [min]

435067

z [mm]

(Pt)

0 5 10 15 20 250

0.01

0.02

0.03

0.04

0.05

0.06

t [min]

4367 50

z [mm]

O 2(P

t)

0 5 10 15 20 250

1E-06

2E-06

3E-06

4E-06

5E-06

6E-06

7E-06

t [min]

4367

50

t [s]

T [K]

0 2000 4000

400

450

500

550

CO(Pt) CO

O2(Pt) O (Pt)

Olaf Deutschmann








coverage)


transport models)



simulation



Technical reactor

Olaf Deutschmann


Pre-turbo SCR for large diesel engines:Effect of high pressure and temperature on conversion

C. Hauck, O. Deutschmann, 2014

cool

ai

r

LLK: charge air cooler DOC: diesel oxidation catalyst HK: hydrolysis catalystKMK: coolant cooler DPF: diesel particle filter SCR: SCR catalyst

SC: ammonia trap

charge airexhaustmain cooling circuit

diesel engine

turbo charger

E. Tronconi, I. Nova, C. Ciardelli, D. Chatterjee, M. Weibel; J. Catal. 245 (2007) 1.I. Nova, C. Ciardelli, E. Tronconi, D. Chatterjee, M. Weibel; (2009), AIChE J.55, 6, 1514-1529

At constant mass flow:

Residence time ~ pressureDiffusion ~ 1/pressure

L ~ 22 cm

1 bar

5 bar

Olaf Deutschmann



1 m10 s

1 mm10 ms

10 m 100 s10 nm1 nm0.1 nm

Olaf Deutschmann


Simulation at real driving conditions is very challenging: Continuous variation of all inlet variables

J. Braun, T. Hauber, H. Többen, J. Windmann, P. Zacke, D. Chatterjee, C. Correa, O. Deutschmann, L. Maier, S.Tischer, J. Warnatz, SAE paper 2002-01-0065

Olaf Deutschmann


DETCHEMMONOLITH: Computer program for the numerical simulation of transients in catalytic monoliths

MONOLITHTemperature of the solid structure incl. canning

by a 2D / 3D heat balance

CHANNEL or PLUG 1D or 2D-flow field simulations for a representative number of

channels using boundary layer or plug flow equations

temperature profileat the wall heat source term

time scale ~ 1 s

residence time < 100 msquasi-steady-statetransient

gas phase concentrationstemperature

chemical source termtransport coefficients

DETCHEM - LibraryThermodynamic and transport properties

Detailed reaction mechanisms for gas-phase & surface

S. Tischer, O. Deutschmann, Catal. Today 105 (2005) 407, www.detchem.de

Olaf Deutschmann


Cumulative CO emission in MEVG cycle:Experiment vs. simulation

0

1

2

3

4

5

6

7

8

0 200 400 600 800 1000 1200time [s]

CO

em

issi

on [%

]

0

20

40

60

80

100

cum

ulat

ive

CO

em

issi

on [g

]

inletinlet (cum.)experiment (cum.)simulation (cum.)

Tischer et al. SAE Technical paper 2007-01-1072 2007

Olaf Deutschmann


2 NH3 + NO + NO2 2 N2 + 3 H2O

Selective catalytic reduction (SCR) of NOx emissions by urea solution: Processes between injection and catalyst

(NH2)2CO (l) NH3 (g) + HNCO (g)HNCO (g) + H2O (g) NH3 (g) + CO2 (g)

F. Birkhold, U. Meingast, P. Wassermann, O. Deutschmann. SAE Technical paper 2006-01-0643, SAE 2006 Trans. J. of Fuels and Lubricants (2006), 252F. Birkhold, U. Meingast, P. Wassermann, O. Deutschmann. Appl. Catal. B: Environmental 70 (2007) 119-127

Source: Robert Bosch GmbH

deposit

Olaf Deutschmann


W. Brack, B. Heine, F. Birkhold, M. Kruse, G. Schoch, S. Tischer, O. Deutschmann. Chem. Eng. Sci. 106 ( 2014)1–8.

Modeling of deposit formation in Urea-SCR:Understanding the reaction mechanism

Source: Robert Bosch GmbH

Olaf Deutschmann


Simulation of catalytic converters from first principles:Dream or nightmare?

Complexity

Leng

thTi

me

Elementary reactions on surfaces

Particles and phases

Porous supports

Reactor behavior

DFT

kMC

Reactive flow

AdditivitySpill-over

Diffusion

Continuum mechanics

Transient models for heat and mass transfer

Multi componentParticle Sizes

Pt

Ce

Reactor behavior

Olaf Deutschmann


Acknowledgements - Exhaust-Gas After-Treatment

Academic collaborations

J.-D. Grunwaldt & many colleagues at KIT

U. Nieken, G. Eigenberger (U Stuttgart)E. Tronconi (Politecnico Milano)R. Gläser (U Leipzig)Ch. Beidel, (TU Darmstadt)G. Wachtmeister (TU München)

SFB/TRR 150 (TU Darmstadt, KIT)Deutschmann group at KIT 2011

Funding and industry partners

Dr. Denise Chan A. Gremminger Dr. Claudia Diehm Wolfgang Brack Dr. Ch. Hauck Dr. Luba Maier Dr. SteffenTischer

Olaf Deutschmann


Thank you!Abstract due May 15

J. Emission Control Sci. & Technol. Paper due Aug 31

microkineticmodels for exhaust-gas after-treatment€¦ · isothermal flat bed reactor: spatially...

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