Catalytic combustion: Modeling andcombustion: Modeling and ... · Catalytic combustion: Modeling...

Catalytic combustion: Modeling and SimulationCatalytic combustion: Modeling and Simulation

3rd Combustion School, Salvador, Basil, 04.07.2011

Olaf Deutschmann

Karlsruhe Institute of Technology (KIT), Germany

Institute for Chemical Technology and Polymer Chemistry (ITCP) Institute for Catalysis Research and Technology (IKFT)

KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association www.kit.edu

The University City of KarlsruheThe University City of Karlsruhe

Karlsruhe:

founded 1715300 000 peoplelocated in Baden-Württemberg,SW state of Germany

Several federal institution such as German Supreme Court and Attorney General

Industry: chemical, automobile, energy, IT

2009: Fusion of the University of Karlsruhe and the2009: Fusion of the University of Karlsruhe and the National Research Center to the Karlsruhe Institute of Technology (KIT) with now 8000 employeesand 20000 students

Olaf Deutschmann

Institute for Chemical Technology and Polymer Chemistry2

and 20000 students

Karlsruhe Institute of Technology (KIT):University and National Research Center

The members of Deutschmann groups at KIT are active at the University at Campus South as well as at the National Laboratory at Campus North

y

South as well as at the National Laboratory at Campus North.

Instit te for Catal sis Research and Technolog (IKFT)Institute for Catalysis Research and Technology (IKFT)

Institute for Nuclear and Energy Technology (IKET)

l h l h h l l d l

Institute for Chemical Technology and Polymer Chemistry (ITCP)

Helmholtz Research School Energy‐Related Catalysis

Exhaust Gas Center

Olaf Deutschmann


Heterogeneous reactions: Tools for chemicals and materials synthesis, emission control, and energy conversiony , , gy

CombustionHigh-temperature catalysis catalysis

Emission control75catalysis

45

60

Y,m

m

8090100110120130140150160170180190200210220

Courtesy of J. Eberspächer GmbH& Co 0 15 30 45 60 750

15

30

01020304050607080

Multi-phase flowFuel cells (SOFC) Carbon composite materials

Courtesy of J. Eberspächer GmbH& CoX, mm

Courtesy of J.J. Schneider

Research methods:Research methods: experiment, analytics and diagnostics, model development, numerical simulation, reactor and process design, optimization

Olaf Deutschmann


, p g , p

Catalytic combustion: Modeling and SimulationO tliOutline

1. Motivation2. Principle of catalysis3. Modeling the reactions on the catalytic surface4. Modeling transport in reactions in porous media5. Reactive flow and catalysis6. Transient processes7. Non-uniform inlet conditions8 G h h i8. Gas-phase chemistry9. Catalyst deactivation

Olaf Deutschmann


Catalytic Catalytic combustion today: combustion today: Wide variety of applications, Wide variety of applications, mainly driven by environmental concernsmainly driven by environmental concernsy yy y

Stationary gas turbine

Objectives:remove pollutants gas turbine- remove pollutants

- reduce the formation of pollutants- produce low temperature heat

t bili fl- stabilize flames- avoid and quench open flames

Automotive catalytic converter

Courtesy of Catalytica Combustion Sys.Courtesy of J. Eberspächer GmbH&Co

Olaf Deutschmann


y y y

Catalytic Catalytic combustion today: combustion today: Wide variety of applications, Wide variety of applications, mainly driven by environmental concernsmainly driven by environmental concernsmainly driven by environmental concernsmainly driven by environmental concerns

Objectives:remove pollutants- remove pollutants

- reduce the formation of pollutants- produce low temperature heat

t bili fl- stabilize flames- avoid and quench open flames

VOC removal Domestic gas stove

Portable radiant heater

C f &S

Olaf Deutschmann


Courtesy of Catabrun, Taikisha Ltd.Courtesy of L&S Fireplace ShoppeCourtesy of Catalyst SystemTechnologies

21th century: Diversification of raw materials for energy, fuels, and chemicals

mobility

CatalysisCatalysis

oil sands nuclear power

hydro power

natural gas solar power

chemical productscoal

wind power

bio massbio mass

lOlaf Deutschmann


alges

Complex interaction of physics and chemistry:Multi-scale modeling

Courtesy of J. Eberspächer GmbH& Co

Olaf Deutschmann


Objective of this lecture: Introduction into modeling of catalytic combustion and energy-related catalysisy gy y

Understanding of the underlying physical and chemical processes

Development of elementary reaction mechanisms (molecular level)

Coupling of chemistry with mass and heat transport of technical reactorstiff coupled non-linear PDE/DAE systems

Numerical solution of the resulting DAEs with appropriate inlet and boundary conditions

Optimization of reactor/burner design and operating conditions

E l C t l ti t di t b d fOlaf Deutschmann


Examples: Catalytic converters, radiant burners, and reformers



Olaf Deutschmann


Heterogeneously catalyzed gas-phase reactions:Old concept but still new applications and challengesOld concept but still new applications and challenges

Döbereiner´s lighter (1823)g ( )

Hydrogeny g

O

Water

slowOxygen slow

20°C

very rapid

Platinum

Olaf Deutschmann




Olaf Deutschmann


Heterogeneous catalytic reactions

Olaf Deutschmann


Elementary processes on catalytic reactions: DFT simulations provide thermo-chemical and kinetic data

O2 - dissociation on Rh (111)O2 dissociation on Rh (111)

Pt particles in highly-loaded DOC

Olaf Deutschmann


O.R. Inderwildi, D. Lebiedz, O. Deutschmann, J. Warnatz, J.Chem.Phys. 122 (2005) 034710

Kinetic Monte Carlo Simulation of surface reactions and diffusion: CO oxidation on Pt nanoperticlep

2 CO + O2 -> 2 CO2CO: blue O: redCO: blue O: redCatalyst atom (Pt): white Washcoat molecule (Al2O3): greyAdsorption sites: yellow

Olaf Deutschmann


Adsorption sites: yellowKunz, Deutschmann, 2006

Modeling heterogeneous reactions: Molecular picture leads to mechanistic model

PtPt

Ba

cΘ iii

Surface coverage

ΓMsΘ iii

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

Surface reaction rate

Γi Γt

SR j

jk

ikijk

kcks

'

f

O. Deutschmann. Chapter 6.6 in

Rate expression

s

1

expexpN

i

iiμi

aβkf RT

ΘεΘ

RTE

TAk kkikk

k

Olaf Deutschmann


O eutsc a C apte 6 6Handbook of Heterogeneous Catalysis, 2007

1i RTRT

Proposed surface reaction mechanism on Pt:Mean field approximation

D. Chatterjee, O. Deutschmann, J. Warnatz. Faraday Discuss. 119 (2001) 371

Olaf Deutschmann


j , , y ( )J. Koop, O. Deutschmannn. Appl. Catal. B: Env. 91 (2009) 47

Development detailed reaction mechanisms for heterogeneously catalyzed gas-phase reactionsheterogeneously catalyzed gas phase reactions

Surface science studies TheoryAnalogy to gas phase(TPD, XPS, XRD, AES, TEM, FEM,

FIM, STM, SFG …)

Theory (ab-intio, DFT, BOC-MP, UBI-QEP, TS, Collision)

Analogy to gas phase kinetics, organometallics

Mechanism (Idea)

Lab experiments(conversion, selectivty,

Modeling of lab reactors(including appropriate models for gas

h ki ti d h t & t tignition/extinction temperatures,spatial & temporal profiles,

coverages)

phase kinetics and heat & mass transport

Comparison of measured and computed data

Sensitivity analysis &Evaluation of crucial

parameters

Revised mechanismReliable mechanism

Olaf Deutschmann


O. Deutschmann. Chapter 6.6 in Handbook of Heterogeneous Catalysis, 2007

Conversion of a synthetic exhaust in a real three way catalyst: Steady-state conditions

Laboratory experiments at well-definedLaboratory experiments at well defined conditions, e.g. differentially operatedreactors (no gradients),are used for first model evaluationare used for first model evaluation

0.8

1.0

0.8

1.0

0.8

1.0C3H6 CO NO

vers

ion

0.60.60.6

0.8

experimentsimulation

conv

0.2

0.4

0.2

0.4

0.2

0.4

0.00.0

temperature [°C]

0.0200 400 600 200 400 600 200 400 600

Olaf Deutschmann


temperature [ C]

Different approaches to model reaction kinetics

Elementary Kinetics Global Kinetics Data basedElementary Kinetics Global Kinetics Data based

Splines NOCOHCInhib GGG

OCOTktd

COd

/.

][][)(][ 21

Neural Networks 701 .][NOKG NONO

Look-up Tables

Olaf Deutschmann


Adapted from M. Votsmeier

Modeling surface reaction kinetics:Elementary Reactions versus Global Rate Expressions

O + 2 Pt 2 PtO2 CO + O 2 CO2Global: 13 Reactions Elementary: 16 Reactions

O2 + 2 Pt 2 PtOCO + Pt PtCO

H2 + 2 Pt 2 PtHNO P P NO

2 CO + O2 2 CO2

2 H2 + O2 2 H2OC3H6 + 4.5 O2 3 CO2 + 3 H2O

CO + H O CO + H

NO + Pt PtNO

PtCO + PtO CO2 + 2 Pt2 PtH + PtO H2O + 3 Pt

CO + H2O CO2 + H2

C3H6 + 6 H2O 3 CO2 + 9 H2

Ce2O3 + 0.5 O2 Ce2O4

PtC + PtO PtCO + PtCO + Ce2O3 + Pt Ce2O4 + PtC

C3H6 + 3 PtO + 6 Pt 3 PtCO + 6 PtH

Ce2O3 + NO Ce2O4 + 0.5 N2

Ce2O4 + CO Ce2O3 + CO2Ce2O4 + 2 H2 Ce2O3 + H2O

C3H6 3 PtO 6 Pt 3 PtCO 6 PtH

PtNO + Pt PtO + PtNPtNO + PtO PtNO2 + Pt

2 PtN N + 2 Pt

2 4 2 2 3 29 Ce2O4 + C3H6 9 Ce2O3 + 3 CO2 +3 H2O

NO + 0.5 O2 NO2

Pt + CO PtC + 0 5 O

2 PtN N2 + 2 Pt

PtO + Ce2O3 Ce2O4 + PtO2 + 2 Ce2O3 2 Ce2O4

Pt + CO PtC + 0.5 O2

NO + Ce2O4 Ce2O4-NO

CO + Ce2O4 CO2 + Ce2O32 H2 + Ce2O4 H2O + Ce2O3

44 Parameter33 + ?? Parameter

Olaf Deutschmann


44 ParameterAdapted from M. Votsmeier



Olaf Deutschmann


Coupling of diffusion and reaction

Olaf Deutschmann


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

Ageo

A t

microscopic site density macroscopic catalyst area → Fcat/geo = Acat / Ageo

Acat

iiisi sMFj cat/geo,

ii

Φ )tanh(Effectiveness factor

ii Φ

ii D

sLΦ

0,,eff iii cD

Olaf Deutschmann


HC-SCR on Pt/Al2O3: Impact of washcoat transport limitation on conversion

Conditions:

500 ppm C3H6, 500 ppm NO, 5 Vol.-% O2, in N2, 6 slpm, u = 0.63 m/s; T = 570 K pp 3 6 pp 2 2 p

Olaf Deutschmann


D. Chatterjee, O. Deutschmann, 2000

NO oxidation on Pt/Al2O3: Impact of washcoat transport limitation on conversion

1.0

no washcoat model0.8

ersi

on 0.6

Ox

conv

e

with washcoat model0.4

NO with washcoat model

0.2

500 600 700 8000.0

Temperature [K]Conditions: 500 ppm NO, 1 Vol.-% O2 in N2

500 600 700 800

Olaf Deutschmann


D. Chatterjee, O. Deutschmann, 2000

Modeling reaction and transport in porous media: 1d reaction-diffusion equations

Washcoat is treated as continuum

Discretization of the washcoat normal to the gas-phase-washcoat boundary at each

Wc sgs NNK '

radial and axial position

0 ,eff

iii

i sMr

cD ),...,1( gNi

g

jks

kj

jk

fiki cks11

),...,1( sgg NNNi 0is0

W

,effW,

surf )0(

r

iiiri r

cDrjj

Olaf Deutschmann


Understanding the interaction of diffusion and reaction: Potential for reduced catalyst costs by zone coating

Reactant concentration in a complex shaped channel

fluidfluid

washcoatwashcoat

Olaf Deutschmann


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



Olaf Deutschmann


Modeling the flow in the channel

General: Transient 3D Navier-Stokes equations + species mass balances + heat balancesq p

Simplifying assumptions often made:No direct transients cylindrical channel no axial (and radial) diffusion

Olaf Deutschmann


No direct transients, cylindrical channel, no axial (and radial) diffusion

Most general approach for modeling laminar flow fields: Transient 3D Navier-Stokes equationsq

Total mass mS

xv

t i

i

Momentum i

j

ij

ij

jii gxx

px

vvtv

k

kij

i

j

j

iij x

vxv

xv

32

Species‘ mass

jj

hom,i

jiiji Rxj

xYv

tY

j

i

j

ii

i

iji x

TTD

xXD

XYj

T

M,

Heat transport

jj xxt

h

, Svpvpjhvh j

jkjjqj

g

,,

N

jiijq jhxTj

solid phase

hSxx

vtxxt k

jkj

jjj

1ijx

hS

xT

xth

jj

ATTSh

44

refsolidradext , p

temperature

g

1

N

iii ThYh

jj

Equation of state(perfect gas)

g

1

N

iiiMX

RTp

i

i

N

j j

ji M

Y

MYX

g

1

1

Olaf Deutschmann


1i

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

no washcoatno washcoatdiffusionlimitation

porousmediamediamodel

NO profiles at lean conditions at 250°C (steady-state operation)CFD code: Fluent + DETCHEM

Olaf Deutschmann


CFD code: Fluent + DETCHEM N. Mladenov, J. Koop, S. Tischer, O. Deutschmann. Chem. Eng. Sci. 65 (2010) 812

Simulation of a catalytic radiant burner with heat recuperationwith heat recuperation

• Steady satet 2D laminar flow• Steady-satet 2D laminar flow• Detailed heterogeneous and homogeneoous gas-phase reaction• External radiation heat loss

J.M. Redenius, L.D. Schmidt, O. Deutschmann. AIChE J. 47 (2001) 1177

• External radiation heat loss• Internal thermal radiation, and heat conduction in solid and gas-phase• FLUENT + DETCHEM (elliptisch)

Olaf Deutschmann


• FLUENT + DETCHEM (elliptisch)

Model simplification by assuming a cylindrical channel and neglecting axial diffusion: Boundary-layer equationsg g y y q

vru

1Total mass flux

Axial momentum flux

rrz

gurpvuruu

11

E th l fl

Axial momentum flux zgr

rrrzrrz

hh 11Enthalpy flux rrqrrz

purvhr

rzuh

11

Species mass flux iiii Mr

rrrvYr

rzuY

11 ji

Coupling between surface reactions and flow field:

ji,wall = Fcat/geo i Mi si

Olaf Deutschmann


Catalytic combustion of natural gas in catalytic channel: 2D Navier-Stokes and 2D Boundary layer approachy y pp

CH4 + 2 O2 –--Pt/Pd----> CO2 + 2 H2OCH4 2 O2 CO2 2 H2OBoundary Layer Eq.

Navier Stokes EqNavier-Stokes-Eq.

L L Raja R J Kee O Deutschmann J Warnatz L DL. L. Raja, R. J. Kee, O. Deutschmann, J. Warnatz, L. D. Schmidt. Catalysis Today 59 (2000) 47-60.

Computed CO concentrations in single monolith channelg

No significant differences

Axial diffusion can be neglected

Olaf Deutschmann


Catalytic combustion of natural gas in catalytic channel: 2D Navier-Stokes, 2D Boundary layer, and 1d Plug flow approach, y y , g pp

1D – Plug-Flow-Model over estimates conversion

Use of mass transfer coefficient is difficult due to large reaction rate causing strong variation oif the Sherwood number

Olaf Deutschmann


L. L. Raja, R. J. Kee, O. Deutschmann, J. Warnatz, L. D. Schmidt. Catalysis Today 59 (2000) 47-60.



Olaf Deutschmann


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

MONOLITHMONOLITHTemperature of the solid structure incl. canning

by a 2D / 3D heat balance

temperature profileat the wall heat source term

time scale ~ 1 s

residence time < 100 msquasi-steady-statetransient

CHANNEL or PLUG 1D or 2D-flow field simulations for a representative number of1D or 2D flow field simulations for a representative number of

channels using boundary layer or plug flow equations

gas phase concentrations chemical source termgas phase concentrationstemperature

chemical source termtransport coefficients

DETCHEM - LibraryDETCHEM - LibraryThermodynamic and transport properties

Detailed reaction mechanisms for gas-phase & surface

Olaf Deutschmann


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

Modeling the temperature of the solid phase of the monolith: Transient three-dimensional heat balancemonolith: Transient three-dimensional heat balance

Temperaturepp c

qc

Tt

T

monolith2monolith

Heat source termsurface

gas2r

Trq

Olaf Deutschmann


DETCHEMMONOLITH

Selecting representative channelsSelecting representative channels

Cluster-Agglomeration:channels may differ in:

X2 a

X2 b

ywall temperature profileinlet conditions discrete vectors discrete vectors

x=(x1,x2,..)

X1

X1

X1

X1

X2 c

X2 d

Clustering of „similair“ vectors

Vectors in one cluster are represented by an averaged vector

Olaf Deutschmann


X1

X1

S. Tischer, O. Deutschmann. Catalysis Today 105 (2005) 407-413

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

Olaf Deutschmann


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

Pollutant reduction in a three-way catalyst during cold start-up: Simulation of a driving cycle

Olaf Deutschmann


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

Cumulative CO emission in MEVG cycle:Experiment vs simulationExperiment vs. simulation

8 100

6

780 n

[g]

inletinlet (cum.)experiment (cum.)

5

6

on [%

]

60

emis

sion

experiment (cum.)simulation (cum.)

3

4

O e

mis

sio

40 ve C

O e

2

3

CO

20

cum

ulat

iv

0

1

0

c

0 200 400 600 800 1000 1200time [s]

Olaf Deutschmann


Tischer et al. SAE Technical paper 2007-01-1072 2007Funded by Corning, 2006-2009



Olaf Deutschmann


Spatially non-uniform inlet conditions:Non-efficient use of catalyst materialsy

Courtesy of J. Eberspächer GmbH& Co

Olaf Deutschmann


Simulation reveals consequences of design restrictions: Spatial non-uniformity increases pollution emissions

Non-uniform flow distributionat converter front face

Temperature after 40 s Non-uniform flow distributionat converter front face Non uniform flow distribution

Temperature after 40 s pUniform flow distribution uniform

non uniformnon-uniform

Olaf Deutschmann


J. Windmann, P. Zacke, S.Tischer, O. Deutschmann, J. Warnatz, SAE paper 2003-01-0937 (2003)

High-temperature catalysis: Compact and autothermal production of hydrogen in few millisecondsproduction of hydrogen in few milliseconds

5-50 m thick oxide layer5 50 m thick oxide layer containing catalyst particles (Pt, Rh) of nm-size

COCO + 2 H+ 2 H OOCHCH + 2 O+ 2 O

CHCH44 + ½ O+ ½ O22 CO + 2 HCO + 2 H22

High-temperature (1000°C) Rh catalyst

COCO22 + 2 H+ 2 H22OOCHCH44 + 2 O+ 2 O22

converting natural gas into CO and H2

in less than 5 ms

without any additional energy supply

Olaf Deutschmann


D.A. Hickman, L.D. Schmidt, Science 259 (1993) 343

Partial oxidation of CHPartial oxidation of CH4 4 on on RhRh at 1 bar: Computed temperature at 1 bar: Computed temperature and concentration profiles during lightand concentration profiles during light--offoff

CHCH + ½ O+ ½ O CO + 2 HCO + 2 H

COCO22 + 2 H+ 2 H22OOCHCH44 + 2 O+ 2 O22

CHCH44 + ½ O+ ½ O22 CO + 2 HCO + 2 H22

Olaf Deutschmann


R. Schwiedernoch, S. Tischer, C. Correa, O. Deutschmann, Chem. Eng. Sci., 58 (2003) 633-642

CPOX of CHCPOX of CH4 4 on on RhRh in single channel at steady state: in single channel at steady state: 2d Raman profiles vs. computation (Mantzaras et al.)2d Raman profiles vs. computation (Mantzaras et al.)p p ( )p p ( )

1100

1150

p = 6 bar φ = 4 T = 566K(K)

1000

1050

1100upperlower

p = 6 bar, φ = 4, TIN = 566K,

38% H2O addition

T WA

LL(

33

0 5 10 15 20 25 301000

Wall

T

x (cm)

123

123

xx CO CH4y (m

m)

cL0.08 0.15 0.22 0.29

0

330.00 0.05 0.10 0.15

0

heig

ht y cL

012

012

xx H2O O2

Cha

nnel

0.00 0.05 0.10 0.150

0.35 0.40 0.45 0.500C

Mole fraction Mole fraction

Olaf Deutschmann


A. Schneider, J. Mantzaras, P. Jansohn et al. Proc. Comb. Inst. 31 (2007)

High temperature catalysis: Technology for production of hydrogen, syngas, olefins, and liquid hydrocarbons

Natural gas Synthesis gas

CHCH + ½ O+ ½ O CO + 2 HCO + 2 HMeOHMeOH,, DME, DieselDME, Diesel

Paraffins Olefins

CHCH44 + ½ O+ ½ O22 CO + 2 HCO + 2 H22O. Deutschmann, L.D. Schmidt., AIChE J. 44 (1998) 2465-2476

CC22HH66 + ½ O+ ½ O2 2 CC22HH4 4 + 2 H+ 2 H22OOParaffins Olefins

D.K. Zerkle, M.D. Allendorf, M. Wolf, O. Deutschmann. J. Catal. 196 (2000) 18-39

CHCH33CHCH22OH + ½ OOH + ½ O22 + 2 H+ 2 H22OO 5 H5 H22 + 2 CO+ 2 CO22

Ethanol Hydrogen

33 22 2 2 22 22 22N. Hebben, C. Diehm, O. Deutschmann, Appl. Catal. A 388 (2010) 225

Gasoline, Diesel Hydrogen

CCnnHHmm + + nn//22 OO22 + + n HH22OO ((n+mn+m/2) H/2) H22 + n CO+ n CO22M. Hartmann, L. Maier, O. Deutschmann, Combustion and Flame 157 (2010) 1771

CCnnHHmm + 2+ 2n HH22OO n COn CO22 + + (2n+m/2) HH22

Steam reforming

Olaf Deutschmann


B. Schädel, O. Deutschmann, Stud. Surf. Sci. & Catal. 167 (2007) 207



Olaf Deutschmann


Interaction of physical and chemical processes in catalytic monoliths

Olaf Deutschmann


Example: More efficient technology for auxiliary power supply in automobile vehicles needed

Idling long-haul trucks consumes 1 billion gallons of diesel fuel annually in the USA 11 million tons CO2, 180,000 tons NOx, 5000 tons particulates!

Olaf Deutschmann


On-board catalytic partial oxidation (CPOX) of logistic fuels provides electricity and reduces pollutant emissions

Tailgas recycling (CO2/H2O)

y

SOFCH2, COAIR CPOx

R f SOFCH2, COReformer

• n‐hexane

PEMH2WGS

Improved H ‐ SCR 40‐60% el.

• n‐octane• n‐decane• n‐dodecane

i t

Catalytic

Start‐upH2 ‐ SCR efficiency• i‐octane

• 1‐hexene• cylcohexane• methyl‐

cyclohexaneConverter

Exhaust ExhaustFuel

Idle state: < 5%Full load: < 30%el. efficiency

cyclohexane• benzene• toluene• ethanol

• (mixtures thereof)

• gasoline• diesel

Olaf Deutschmann


CPOX lab reactor set-up: Well-defined inlet and boundary conditions

P l f id i i f tPulse-free rapid mixing of up to eight gaseous reactants below auto-ignition temperature

900 cpsi Rh coated honeycomb

Autothermal operation

C/O: 0 8 2 0C/O: 0.8 – 2.0Flow rate: 2 – 6 splm w/ & w/o CO2 and H2O addition

Product analysis: FT-IR, MS, GC/MS, O2 sensorFT IR, MS, GC/MS, O2 sensor

Olaf Deutschmann


M. Hartmann, T. Kaltschmitt, O. Deutschmann. Catalysis Today 147 (2009) S204

Fuel composition (aliphats, aromatics, olefins) and C/O ratio determines both yields in hydrogen and coke precursorsy y g p

Variation of chain length Variation of structure11

Variation of chain length Variation of structure

0.90.9

0.8

H2 Y

ield

0.8

H2 Y

ield

0.7

H

i-hexanecyclohexane1-hexene

0.7

H

n-hexanen-octanen-decane

d d

0.60 8 0 9 1 1 1 1 2 1 3

benzene

0.60 8 0 9 1 1 1 1 2 1 3

n-dodecane

0.8 0.9 1 1.1 1.2 1.3

C/O

0.8 0.9 1 1.1 1.2 1.3

C/O


Olaf Deutschmann


, , y y ( )

Fuel composition (aliphats, aromatics, olefins) and C/O ratio determines both yields in hydrogen and coke precursorsy y g p

Coke precursors By products in CPOX of iso octaneCoke precursors

0.03 Ethylene10000

i C H CH10000

i C H CH10000

i C H CH

By-products in CPOX of iso-octane

0.03 Ethylene

40% tol / 60% n-octane30% tol / 70% n-octane20% tol / 80% n-octane 7000

8000

9000

pm)

i-C8 H18

19.300 ppm

at C/O = 2.0

CH4

i-Butylene7000

8000

9000

pm)

i-C8 H18

19.300 ppm

at C/O = 2.0

CH4

i-Butylene7000

8000

9000

pm)

i-C8 H18

19.300 ppm

at C/O = 2.0

CH4

i-Butylene0.02

C Y

ield

Propylene

100% n-octane

5000

6000

7000

ntra

tion

(pp i-Butylene

5000

6000

7000

ntra

tion

(pp i-Butylene

5000

6000

7000

ntra

tion

(pp i-Butylene

0.0140% tol / 60% n-octane30% tol / 70% n-octane20% tol / 80% n-octane

100% n-oktane 2000

3000

4000

Con

cen

Propylene

Acetaldehyde

Ethane & Ethylene2000

3000

4000

Con

cen

Propylene

Acetaldehyde

Ethane & Ethylene2000

3000

4000

Con

cen

Propylene

Acetaldehyde

Ethane & Ethylene

00.8 0.9 1 1.1 1.2

0

1000

0.8 1 1.2 1.4 1.6 1.8 2

Acetaldehyde

0

1000

0.8 1 1.2 1.4 1.6 1.8 2

Acetaldehyde

0

1000

0.8 1 1.2 1.4 1.6 1.8 2

Acetaldehyde

M Hartmann T Kaltschmitt O Deutschmann Catalysis Today 147 (2009) S204

C/O0.8 1 1.2 1.4 1.6 1.8 2

C/O0.8 1 1.2 1.4 1.6 1.8 2

C/O0.8 1 1.2 1.4 1.6 1.8 2

C/O

Olaf Deutschmann



CPOX of iso-octane over rhodium: Influence of residence time and C/O ratio on hydrogen formation and by-product formation

0.015

Ethylene

6 SLPM

0.01

Yiel

d

5 SLPM4 SLPM3 SLPM2 SLPM

0.005

Ethy

lene

Y

00.8 0.9 1 1.1 1.2 1.3

C/O

M. Hartmann, L. Maier, O. Deutschmann, Applied Catalysis A: General 391 (2011) 144–152.L Maier M Hartmann O Deutschmann Combust Flame 158 (2011) 796 808

Olaf Deutschmann


L. Maier, M. Hartmann, O. Deutschmann, Combust. Flame 158 (2011) 796-808.

CPOX of i-octane: Modeling based on detailed reaction mechanisms on the catalyst and in the gas-phasemechanisms on the catalyst and in the gas phase

Surface reactions

Detailed reaction mechanism for C1-C3 species: 111 ti 31 f i111 reactions, 31 surface species

C4+ hydrocarbons: lumped steps assuming a fast dissociation leading to adsorbed C1-C3 speciesM. Hartmann, L. Maier, O. Deutschmann, Combustion and Flame 2010, 157, 1771.

Elementary-step gas-phase reaction mechanisms

LLNL: 7193 reactions among 857 species and 17 third bodiesH. J. Curran, P. Gaffuri, W.J. Pitz, C.K. Westbrook. Combustion and Flame 129 (2002) 253

Golovichev, Chalmers University: 690 reactions, 130 speciesV. I. Golovitchev, F. Tao, L. Chomial, in SAE paper 1999-01-3552

Olaf Deutschmann


CPOX of i-octane: Computed temperature distribution in the reactor

Olaf Deutschmann


L. Maier, M. Hartmann, O. Deutschmann, Combust. Flame 158 (2011) 796–808.

CPOX of HC: Counter-intuitive increase of yields with decreasing residence time understood

catalyst

Olaf Deutschmann



CPOX of iso-octane in catalytic channel: Numerically predicted 2D species profiles in gas-phase

Olaf Deutschmann


C/O = 1.2, 800°C M. Hartmann, L. Maier, O. Deutschmann, Combust. Flame 157 (2010) 1771

CPOX of i-octane: Coke precursors are formed in the gas phase in the catalytic zone and downstreamp y

catalyst catalyst

C/O = 1.0 5 slpm

Olaf Deutschmann



CPOX of iso-octane:Coke precursor formation also depends on flow ratep p

Modeling (lines) versus experiment (symbols)

Flow rate [slpm]

C/O = 1.0

Olaf Deutschmann





Olaf Deutschmann


Small olefins in reformate gas can lead to gas-phase molecular-weight growth and carbon depositsg g p

Olaf Deutschmann


A. Dean, Colorado School of Mines

Coke formation in partial oxidation of iso-octane: Carbon distribution along the reactor (w/o catalyst)

C/O = 1.6, 1108 K, 6 SLPM. C3-C4 olefins contain 1,2-propadiene, propene, propyne, n-butene (1-buten, 2-butene), iso-butene, 1,3-butadiene; PAH contains naphthalene, anthracene, pyrene. Embedded photo shows the tubular quartz reactor after operation.

Olaf Deutschmann


T. Kaltschmitt, L. Maier, O. Deutschmann. Proceedings of the Combustion Institute 33 (2011) 3177

CPOX of i-octane: Coke formation on the downstream section of the catalyst at rich conditions

C/O = 0.8 C/O = 1.2

Numerically predicted surface coverage along the monolithic catalyst

Olaf Deutschmann


M. Hartmann, L. Maier, O. Deutschmann, Combust. Flame 157 (2010) 1771

Catalyst deactivation by coking:TEM-Images of the Rh particlesg p

d = 0 6 mmd = 0.6 mm

10 nm 10 nmcarbon layer

Rh RhRh RhAl2O3

Rh2 3

support

Olaf Deutschmann


M. Hartmann, B. Reznik, O. Deutschmann, 2010, to be published

Hierarchical modeling in catalytic combustion: Reactor simulation from first principlesp p

Transient models for heat and mass transfer

ng

th

me

Reactor

Continuum mechanics

Len T

i Reactor behavior

AdditivitySpill over

Diffusion

kMC

Reactive flowSpill-over

Pt

Porous supports

DFT

kMC

DFTMulti componentParticle Sizes

Ba

Elementary reactions on surfaces

Particles and phases

Olaf Deutschmann


Complexity

Acknowledgements

A. G. Eigenberger, U. Nieken (U Stuttgart), H -G Bock (U Heidelberg) R Behm (Ulm)

Deutschmann group, 2010H.-G. Bock (U Heidelberg), R. Behm (Ulm),J. J. Schneider (U Darmstadt), G. Müller (U Wuppertal),L. D. Schmidt (U Minnesota), G. Saracco (Politecnico Turino),R J Kee A M Dean (CSM) D G Goodwin (CalTec)R.J. Kee, A.M. Dean (CSM), D.G. Goodwin (CalTec),P. Ronney (USC LA), K. Maruta (Tokyo)Attera Worayingyong, Pinsuda Viravathana (Kasetsart U)

Schleicher-StiftungBaden-Baden

Olaf Deutschmann


Muito obrigado!Muito obrigado!Muito obrigado!Muito obrigado!

Light-off of CPOX of gasoline

Olaf Deutschmann


Light-off of CPOX of gasoline

Catalytic combustion: Modeling andcombustion: Modeling and ... · Catalytic combustion: Modeling...

Documents

Transcript of Catalytic combustion: Modeling andcombustion: Modeling and ... · Catalytic combustion: Modeling...