Title: Heterogeneous Catalysis Opportunities and challenges
1Heterogeneous CatalysisOpportunities and
challenges
J. K. Nørskov Center for Atomic-scale
Materials Physics Technical University of
Denmark norskov_at_fysik.dtu.dk
- Challenges
- Societal needs
- Developing the basic understanding
- Opportunities
- Designing at the nano-scale
2Challenges I
Dream reactions waiting for a catalyst
Jens Rostrup-Nielsen XVII Sympósio
Iberoamericano de Catálisis, July 16-21, 2000
3Challenges II
- Dreaming on .
- Heterogeneous catalysts for assymmetric synthesis
- Photolytic water splitting (hydrogen economy)
- Biomimetics, synthetic enzymes
- Non-thermal processes in general
- (e.g. electro- and photocatalysis)
-
See E. Derouane, CATTECH 5, 226 (2001)
4Challenges III
- The science of heterogeneous catalysis
- A comprehensive scientific basis
- Much has been done
- Much more is needed (oxides, size effects,
photocatalysis, electrocatalysis, relation to
homogeneous and enzyme catalysis ) - Making the insight useful!
- The ultimate test
5Opportunities- design at the nano-scale
- Rational catalyst design
- Discovery on the basis of insight
- Data-driven methods
- - Accelerated discovery by access to
- large amounts of data
- Bio-inspired catalysis
6Rational catalyst design
- What determines the catalytic
- activity/selectivity/lifetime ?
- How can we affect it?
- - We have tremendous new possibilities
7Ammonia synthesisN23H2? 2NH3
Ozaki and Aika, Catalysis 1 (Anderson and
Boudart, Ed.)
8Ammonia synthesis over Ru
Ru(0001)
step
Logadottir, Nørskov
9Steps do everything
Au decorates steps Hwang, Schroder, Gunther,
Behm, Phys. Rev. Lett. 67, 3279 (1991)
Dahl, Logadottir, Egeberg, Larsen, Chorkendorff,
Törnqvist, Nørskov, Phys.Rev.Lett. 83, 1814
(1999)
10The Brønsted-Evans-Polanyi relation
Logatottir, Rod, Nørskov, Hammer, Dahl, Jacobsen,
J. Catal. 197, 229 (2001)
11Calculated ammonia synthesis rates400 C, 50 bar,
H2N231, 5 NH3
Logatottir, Rod, Nørskov, Hammer, Dahl, Jacobsen,
J. Catal. 197, 229 (2001)
12Interpolation in the periodic table
Jacobsen, Dahl, Clausen, Bahn, Logadottir,
Nørskov, JACS 123 (2001) 8404.
13Interpolation in the periodic table
Jacobsen, Dahl, Clausen, Bahn, Logadottir,
Nørskov, JACS 123 (2001) 8404.
14Measured ammonia synthesis rates 400 C, 50 bar,
H2N231
Jacobsen, Dahl, Clausen, Bahn, Logadottir,
Nørskov, JACS 123 (2001) 8404.
15Data driven methods
- High throughput screening
- Direct testing of many catalysts, fast,
efficiently - Data mining
- Correlating catalytic activity/selectivity/
durability to descriptors that can be tabulated
16H. Toulhoat and P. Raybaud Workshop Catalysis
from First Principles Vienna 02/02
Using DFT calculations in the search of
prospective catalysts
- The object of the game
- Find sets of descriptors Dik of solid materials
Mi , and a mathematical model F such that Aij
being the Turn Over Frequency of Mi as catalyst
for the reaction j at operationg conditions Cj
one has - Identify ranges of Dik that maximize F
- Screen Databases of Materials Properties before
screening real materials - Better if one descriptor is sufficient, but do
not take it for granted - Much better if F has a sound physical basis
- Adsorbate/substrate bond strengths should provide
good descriptors according to the Sabatier
principle
17H. Toulhoat and P. Raybaud Workshop Catalysis
from First Principles Vienna 02/02
Using DFT calculations in the search of
prospective catalysts
18H. Toulhoat and P. Raybaud Workshop Catalysis
from First Principles Vienna 02/02
Using DFT calculations in the search of
prospective catalysts
- E MC _at_ Fm-3m carbides is rather consistent with
simple chemisorption models - Onset of dissociative chemisorption as MC bond
strength increases
19H. Toulhoat and P. Raybaud Workshop Catalysis
from First Principles Vienna 02/02
Using DFT calculations in the search of
prospective catalysts
- The experimental Alloying effects is correctly
predicted
20Getting data/descriptors
- Structure (in situ)
- Spectroscopy (in situ)
- Surface thermochemistry
- Calculations
-
- There is a large need for systematic data
- - and for good descriptors
21Structure-activity Correlation Hydrodesulfurizatio
n of thiophene
Topsøe, Clausen, Massoth Hydrotreating Catalysis,
Science and Technology (Anderson and Boudart
(Eds.), Springer (1996).
22Descriptors from spectroscopy
23Single crystal microcalorimerty
Larsen, Starr, Campbell, Chem.Thermodyn. 33, 333
(2001) Brown, Kose, King, Chem. Rev. 98, 797
(1998).
24Descriptors from DFT
Correlation between adsorption energies and
activation barriers and the d-band center
Mavrikakis , Hammer, Nørskov Phys. Rev. Lett. 81,
2819 (1998)
25 CO tolerance of Pt alloy anodes for PEM fuel
cells
Pt
M
S. Gottesfeld et al., J. Electrochem. Soc. 148
(2001) A11.
Christoffersen, Liu, Ruban, Skriver, Nørskov,
J.Catal. 199, 123 (2001)
26How can the d-band center be changed?
Calculated d band shifts
Overlayer
Host
Ruban, Hammer, Stoltze, Skriver, Nørskov,
J.Mol.Catal. A 115, 421 (1997)
27Methane activation
Transition state for CH4 dissociation on Ni(211)
b
Bengaard, Rostrup-Nielsen, Nørskov
28Methane activation on Ni/Ru
Egeberg, Chorkendorff, Catal. Lett. 77, 207
(2001)
29Lessons from biology
- Catalysis at ambient temperature and pressure
- Extreme selectivity
- Direct coupling of energy into the important
reaction coordinate (non-thermal catalysis)
30Nitrogenase
nitrogenase
ATP
complex formation
Fe protein
4Fe-4S cluster
MoFe protein
P-cluster
nucleotide replacement
ATP cleavage electron transfer
FeMo cofactor
Fe protein
reduction
complex dissociation
Burgess, Lowe, Chem. Rev. 96, 2983
(1996) Schindelin, Kisker, Schlessman, Howard,
Rees, Nature 387, 370 (1997)
31N2 hydrogenation on FeMoco
Rod, Nørskov JACS 122, 12751 (2000)
32The Fe Protein cycle
E
MoFe protein
Fe protein
ATP
1)
4Fe-4S cluster
FeMoco
P-cluster
2)
E
3)
ADP
E
4)
See also Spee, Arendsen, Wassnik, Marrit, Hagen,
Haaker, FEBS Lett. 432, 55 (1998)
33Comparing the FeMoco and Ru(0001)
Rod, Logadottir, Nørskov J.Chem.Phys.
112, 5343 (2000)
34Status
- Well developed basic understanding
theory-experiment - Beginning to be able to use it directly in
catalyst design - Some activity-descriptor correlations
- Host of new in situ methods for catalyst
characterization - New very powerful screening methods
- We have a starting point which is radically
different from the situation 5 or 10 years ago!
35Moving forward
- More basic understanding theory-experiment
- Integration of the conceptual framework for
heterogeneous, homogeneous and enzyme catalysis - More systematic data (descriptors)
- Better synthesis methods
- Better coupling of catalyst design and process
engineering - INTEGRATION
36Promoting development
An integrated approach
Experiments, models
Synthesis testing characterization
Theory