catalysis & surface science hans.pdfnobel prize for the classical surface science approach to...

Catalysis & Surface Science

How much do we understand?

J W (Hans) NiemantsverdrietSchuit Institute of Catalysis

Eindhoven University of Technology

Eindhoven, The Netherlands

Schuit Institute of Catalysis


Surface Science & Catalysis

Surface science in the pastthe ideal world before the STM

and the complex world thereafter

Models of supported catalysts

many opportunities, for example

polymerization catalysis

Surface Science in the Future

How much do we understand?

Nobel Prize for the classical

surface science approach

to heterogeneous catalysis

on the basis of a very thorough

knowledge of physical chemistry,

thermodynamics, spectroscopy, etc.

fcc(100)

fcc(111)

Surface science tools

LEEDLEEDLEEDLEED

0 500 1000 1500 2000energy loss [cm ]-1

1861

2070EELSEELSEELSEELS

300 400 500 600

Temperature (K)

TPDTPDTPDTPD

a perfect world ……?

Ir‘clean’

Ir+carbidic C

Ir + graphitic C

dN

dE

Kinetic Energy (eV)

230 240 250 260 270 280

AES

Scanning Tunneling Microscopy

Contrary to

what we expected …

M.F. Crommie, C.P. Lutz, D.M. Eigler, Nature 363 (1993) 524

Perfect surfaces …… ?

Log (dissociation probability)

The Dominant Role of Steps on Surfaces

Dissociation Probability of N2 on Ru(0001)

Au atoms

passivatethe steps

Eact = 42 kJ/mole

1-2% gold:

Eact = 121 kJ/mole

S. Dahl, A. Logadottir, R. Egberg, J.H. Larsen, I. Chorkendorff, E. Törnqvist, J.K. Nørskov, PRL 83 (1999) 1814

Steps responsible for N2 dissociation!

M.F. Crommie, C.P. Lutz, D.M. Eigler, Nature 363 (1993)524

is all surface chemistry governed by defects?

NO!fortunately notfortunately notfortunately notfortunately not

TP Kinetics of COads+Oads = CO2 on Rh(100)

2.1 2.4 2.7 3.0

-6

-4

-2

0

2

1000 / T (K-1)

300 400 500 600

CO

2fo

rmation r

ate

(a.u

.)

Temperature (K)

COads+ Oads

Rh (100)

θo = 0.16 ML

θco= 0.07 ML

lnr/θo θco (s

-1)

Eact = 103 ± 5 kJ/mol

ν = 1012.7 ±±±± 0.7 s-1

M.J.P. Hopstaken, W.E. van Gennip

and J.W. Niemantsverdriet, Surf Sci 433 (1999) 69

Try Rate equation (Arrhenius):

r = k θO θCO = ν θO θCO e-Eact /RT

Plot: ln (r/ θO θCO) vs 1/T

DFT: Eact = 1.03 eV; ν = 1012 s-1

A. Eichler, Surf Sci 498 (2002) 314

Represents intrinsic chemistry on the entire (100) surface

Traditional Surface science on metal single crystals

is okay for

• Adsorption Studies (Static)

• Reactivity studies, if surface is “sufficiently reactive”

STM: realistic view on surfaces

Compute first

– then validate with selected experiments

The ever increasing impact of DFT calculations

Ethylene decomposition on Rh(100)

D.L.S. Nieskens, A.P. van Bavel, D. Curulla, J.W. Niemantsverdriet

J.Phys.Chem. B 108 (2004) 14541

The most defined wayto do surface science:

Computational Chemistry

DFT; periodic boundary - slab calculations

VASP – Da Capo – etc.

but results need to be validated!

How to model a catalyst?

Particle on a flat support Single crystal surface

Ib Chorkendorff & Hans Niemantsverdriet, Concepts in Modern Catalysis and Kinetics, Wiley-VCH, 2003

electrons

ions

photons

electrons(XPS, AES, EELS, SEM, TEM)

ions(SIMS, LEIS, RBS)

photons(RAIRS, SFG, ATR-IR

EXAFS, XANES)

desorbingmolecules(TPD, TPRS)

Conducting substrate, e.g. Si (100)

thin film (3 – 10 nm) of SiO2 TiO2 Al2O3 etc

Catalyst particle

Supported Model Catalysts

• line of sight detectability of entire systemtesting & characterization on the same phase

• flat geometry; z-coordinate resolved enables AFM (STM) and facilitates quantification

• conductivity prevents charging higher resolution in ‘charged particle techniques’

• no diffusion limitations in kinetic studiesintrinsic kinetics (in batch reactors)

Advantagesof planar model catalysts

TU/e

Mimick Wet Chemical Impregnation by Spincoating

pore volume impregnation

spin coating

Enables industrially realistic model catalysts

R.M. van Hardeveld, P.L.J. Gunter, L.J. van IJzendoorn, W. Wieldraaijer, E.W. Kuipers,

and J.W. Niemantsverdriet, Appl. Surface Sci. 84 (1995) 339 - 346

What do we want to know about Model Catalysts?

TU/e

• Amount of supported material

• Composition and chemical state

• Morphology

• Adsorption of gases

• Kinetics of reactions

Planar Model CatalystsTypical loading of supported material:

0.1 - 10 atoms / nm2

1013to 10

15 atoms per sample of 1 cm2 only

Amount of metal: RBS (XPS, AES, …)

Particle density: AFM (TEM, SEM)

Particle size: AFM (TEM)

Composition: XPS – XANES (SIMS, … )

Adsorbates: ATR-IR (RAIRS, SFG)

E. van Kimmenade, A.E.T. Kuiper, Y. Tamminga, P.C. Thüne, and J.W. Niemantsverdriet, J. Catal. 223 (2004) 134

RutherfordBackscatteringSpectrometry:

Amount of chromium on 1 cm2 model catalyst

Cr

needs accelerator…

µm

µm

AFM: Particle Density and Height

Absorbance

wavenumber (cm-1)

2143 cm

-1

2023cm

-1

2 x 10-4

vacuum

after CO

under CO

1 mbar

0.3 mbar

0.02 mbar

vacuum

2300 2200 2100 2000 1900 1800

Adsorbates on Model Catalysts:

IR detector

ATR-IRCO on Rh /SiO2 / Si(100)

Rh particles: 3-4 nm

Support = ATR Crystal

IR on model catalysts is feasible!

C.M. Leewis, W.M.M. Kessels, M.C.M. van de Sanden, J.W. Niemantsverdriet,

J. Vac. Sci. Technol. A 24 (2006) 296

Morphology Model Catalysts:

Atomic Force Microscopy (AFM)

Scanning Electron Microscopy (ESEM)

Transmission Electron Microscopy:needs special support

Silicon waferSilicon wafer

10 nm silica layer10 nm silica layer

Peter Thüne, TU/e

Chemical State of (Model) Catalysts:

XANES (NEXAFS)

Excellent in situ technique

but

Synchrotron Beamline Needed!

Example: Cobalt Fischer-Tropsch Catalysts

Long term catalyst performance testing

under realistic Fischer-Tropsch synthesis

100 bbl/day slurry bubble column reactor, 230 °C, 20 bar, (H2+CO)

conversion: 50-70 %,

feed gas: 50 vol. % H2, 25 vol. % CO, PH2O = 4-6 bar)

0.0

0.2

0.4

0.6

0.8

1.0

0 10 20 30 40 50 60

Time on line (days)

RIA

Fre

lati

ve

ac

tiv

ity

0 10 20 30 40 50 60

Time on line (days)

Cobalt is expensive;

need to maximize catalyst life

/Al2O3

53% Co0

80% Co0

85%

88%

89%

XANES of wax coated catalystsfrom FT bubble column demonstration reactor

A.M. Saib, A. Borgna, J. van de Loosdrecht, P.J. van Berge, J.W. Niemantsverdriet

Appl. Catal. A: General 312 (2006) 12

No oxidation but reduction of unreduced cobalt.

LURE, ORSAY LURE, ORSAY

Abdool Saib, Armando Borgna, Jan van de Loosdrecht, Peter van Berge, Hans Niemantsverdriet, J. Phys. Chem. B 110 (2006) 8657

AFM Co/SiO2/Si(100) Model Catalysts

Co L3 XANES of Cobalt Compounds

D Bazin et al.

J Catal 189 (2000) 456

L3 XANES = ‘in situ XPS’

XANES of Co/SiO2/Si(100) Oxidation

Question:Do cobalt FTS catalysts oxidize under FTS?

Conclusion:Co/SiO2 highly resistant to oxidation by water

Abdool Saib, Armando Borgna, Jan van de Loosdrecht, Peter van Berge, Hans Niemantsverdriet, J. Phys. Chem. B 110 (2006) 8657

Kinetics Thiophene HDS NiMoS/SiO2

0.00 0.02 0.04 0.06 0.08

0.00

0.02

0.04

0.06

0.08

0.10NiMo/SiO

2

325 °C

350 °C

375 °C

400 °C

r (m

ol T

hio

ph/m

ol N

i*S

)

Pthioph

A. Borgna, E.J.M. Hensen, J.A.R. van

Veen, and J.W. Niemantsverdriet,

J. Catal. 221 (2004) 541

• thiophene heat ofadsorption:

Eact = 84 ±5 kJ/mole

molkJHThioph

ads/58±5-=∆∆∆∆

• activation energy of rate-determining step

• turnover frequency :

0.1 molthiophene /molNi s (400 C)

N

NN

iPriPr

Si

O O

Fe

ClCliPriPr

OH

Silica

Han Wei, C. Müller, D. Vogt, P.C. Thüne, J.W. Niemantsverdriet, Macromol. Rapid Commun. 27 (2006) 279

Between homo- and heterogeneous catalysis:Surface Science Model of a Supported Single-site Catalyst

NNN

iPriPr

Si Cl

iPriPr

Cl

N

NN

iPriPr

Si

O O

Fe

ClCliPriPr

OH

N

NN

iPriPr

Si

O O

iPriPr

OH

SilicaSilica

N

NN

iPriPr

iPriPr

Immobilization Procedure:

Bis imino pyridyl ligand Chlorosilane linker

Add FeCl2

Bind to SiO2 / Silicon Wafer Immobilized catalyst


Han Wei, C. Müller, D. Vogt, P.C. Thüne, J.W. Niemantsverdriet Macromol. Rapid Commun. 27 (2006) 279

Catalysts

N

NN

iPriPr

Si

O O

Fe

ClCliPriPr

OH

Silica

N

NN

iPriPr

Fe

ClCliPriPr

Fe : Cl : N

=

1.0 : 2.1 : 2.8

Catalyst loading : 0.5 / nm2

X-ray Photoelectron Spectroscopy (XPS)


Han Wei, C. Müller, D. Vogt, P.C. Thüne, J.W. Niemantsverdriet, Macromol. Rapid Commun. 27 (2006) 279

Ethylene polymerization in toluene + TIBA at room temperature


Wei Han, Di Wu, Weihua Ming, Hans Niemantsverdriet, Peter Thüne, Langmuir 22 (2006) 7956

cracked polyethylene ‘normal’ polyethylene

160°contact

angle

95°contact

angle

“Cracked” Polyethylene:“super hydrophobic”

N

NN

iPriPr

Si

O O

Fe

ClCliPriPr

OH

Silica

anchored polymerization catalyst:


Homogeneously thick layer of polyethylene

dead catalyst

dead catalyst

+ B(C6F5)3

ZrCl

Cl

Si

+ MAO

anchoring vs polymer morphology

anchored Cr = homogeneous polymer film

non-anchored cluster catalyst = polymer particles

metallocene dispersed in MAO = polymer film topped

by cocatalyst

Cr

SiO2


P Thüne, J. Loos, U. Weingarten, F Muller, W. Kretschmer,

W. Kaminsky, P. Lemstra, J. Niemantsverdriet, Macromolecules 36 (2003) 1440

Surface science has been indispensable for catalysis

However, single crystal surfaces are not as perfect as we once believed; Useful experiments remain feasible

The traditional role of surface science on ‘perfect’ surfaces is taken over by computational chemistry; validation remains important

Supported

Model Catalysts


Surface Science & Catalysis

Realistic Preparation (wet chemistry)

Excellent characterization

Kinetics & Mechanism without Mass Transfer Limitations

•CoMoS, NiMoS and NiWS Hydrodesulfurization Catalysts

•Rhodium Automotive Catalysts

•Bimetallic Selective Hydrogenation Catalysts

•Cobalt Fischer-Tropsch Catalysts

•Polymerization Catalysts; anchored homogeneous complexes

•Carbon Nanotube Growth

Molecular Heterogeneous Catalysisexperimental and theoretical modeling

conceptually understood,but in practice still largely empirical…

ammo

nia

synthe

sis

Langm

uir

Hinshe

lwood

IR

Surfac

e

Scienc

eCom

putatio

nal

chemis

tryBer

zelius

Equilib

rium

Thermody

namics

1800 1900 2000

TST

Knowledge

Fundamental & Applied Catalysis

How much do we know?

catalytic

surface

catalytically active particles on a support

shaped catalyst particles

catalyst bed

in a reactor

1 nm

10 mm

1 µm

1 m

microscopic mesoscopic macroscopic

length and time scales in catalytic processes

Ib Chorkendorff & Hans Niemantsverdriet, Concepts in Modern Catalysis and Kinetics, Wiley-VCH, Weinheim, 2003

How to controlsurface reactivity?

How to controlthe mesoscale?

faster, more flexible

process design?

Translation over time- and lengthscales

nanoparticle

CongratulationsSingapore Catalysis Society

if all parties (ICES + NUS + NTU + … collaborate,

Singapore catalysis can become a world leader!

Succes!

your colleagues at Eindhoven


PhD StudentsMarco Hopstaken (now Philips)Martijn van Hardeveld (now Shell)Herman Borg (now Philips)Arthur de Jong (TU/e)Ton Janssens (now Topsoe)Davy Nieskens (now DOW)Sander van Bavel (now Shell)Wouter van Gennip (now Philips)Maarten JansenFreek ScheijenAshriti Govender (SASOL)Akhtar Hussain

PostdocsDani CurullaRalf Linke (now Jena)

NWO; NCF;

AcknowledgementsSingle Crystal Studies + DFT

CollaborationsBen Nieuwenhuys – TU/eRutger van Santen –TU/eJosep Ricart - Tarragona

PhD StudentsHannie MuijsersPieter Gunter (now Oce)Leon Coulier (now TNO)Emiel van Kimmenade (now TNO)Han Wei (now BASF)Abdool Saib (SASOL)Eero Kontturi (now TKK-Helsinki)Adelaida AndoniPrabashini Moodley (SASOL)Denzil Moodley (SASOL)Gilbere Mannie

PostdocsThomas Weber (now at Shell)Gurram Kishan (now General Electric)Christian Leewis (now ASML)Ramesh Kanaparthi (now ICES)Srilakhsmi Chilukoti (now ICES)Vijay NarkhedeRalf Linke (now Jena)

Planar Model Catalysts – Peter Thüne

CollaborationsBruce Anderson – TU/e (now SASOL)San de Beer – TU/eRob van Veen – Shell - TU/eEmiel Hensen – TU/eJan van de Loosdrecht - SASOLPiet Lemstra – TU/eJohn Chadwick – Basell / DPIRichard van de Sanden – TU/e

VisitorsTracy Bromfield - SASOLPaco Ample – TarragonaLinda Jewell – Wits Univ

VisitorsArmando Borgna – TU/e; now ICESTon Kuiper – PhilipsNoor Asmawati Zahbidi – Univ Tech Petronas

STW; DPI; FOM; SASOL

catalysis & surface science hans.pdfnobel prize for the classical surface science approach to...

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