Heterogeneous Catalysis Opportunities and challenges

1. Heterogeneous CatalysisOpportunities and challenges J. K. Nørskov Center for Atomic-scale Materials Physics Technical University of Denmark norskov@fysik.dtu.dk • Challenges • Societal needs • Developing the basic understanding • Opportunities • Designing at the nano-scale

2. Challenges I Dream reactions waiting for a catalyst: Jens Rostrup-Nielsen: XVII Sympósio Iberoamericano de Catálisis, July 16-21, 2000

3. Challenges 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)

4. Challenges 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

5. Opportunities- 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

6. Rational catalyst design • What determines the catalytic • activity/selectivity/lifetime ? • How can we affect it? • - We have tremendous new possibilities

7. Ammonia synthesisN2+3H2 2NH3 Ozaki and Aika, Catalysis 1 (Anderson and Boudart, Ed.)

8. Ammonia synthesis over Ru Ru(0001) step Logadottir, Nørskov

9. Steps 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)

10. The Brønsted-Evans-Polanyi relation Logatottir, Rod, Nørskov, Hammer, Dahl, Jacobsen, J. Catal. 197, 229 (2001)

11. Calculated ammonia synthesis rates400 C, 50 bar, H2:N2=3:1, 5% NH3 Logatottir, Rod, Nørskov, Hammer, Dahl, Jacobsen, J. Catal. 197, 229 (2001)

12. Interpolation in the periodic table Jacobsen, Dahl, Clausen, Bahn, Logadottir, Nørskov, JACS 123 (2001) 8404.

13. Interpolation in the periodic table Jacobsen, Dahl, Clausen, Bahn, Logadottir, Nørskov, JACS 123 (2001) 8404.

14. Measured ammonia synthesis rates400 C, 50 bar, H2:N2=3:1 Jacobsen, Dahl, Clausen, Bahn, Logadottir, Nørskov, JACS 123 (2001) 8404.

15. Data 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

16. H. 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

17. H. Toulhoat and P. Raybaud Workshop Catalysis from First Principles Vienna 02/02 Using DFT calculations in the search of prospective catalysts

18. H. Toulhoat and P. Raybaud Workshop Catalysis from First Principles Vienna 02/02 Using DFT calculations in the search of prospective catalysts • E MC @ Fm-3m carbides is rather consistent with simple chemisorption models • Onset of dissociative chemisorption as MC bond strength increases

19. H. 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

20. Getting data/descriptors • Structure (in situ) • Spectroscopy (in situ) • Surface thermochemistry • Calculations • … There is a large need for systematic data - and for good descriptors

21. 1.5 HDS activity (x102/mol/g/h) 10 0.5 0 0 1 2 3 Number of Co edge atoms (x1020/g catalyst) Structure-activity Correlation Hydrodesulfurization of thiophene Topsøe, Clausen, Massoth Hydrotreating Catalysis, Science and Technology (Anderson and Boudart (Eds.), Springer (1996).

22. CO TPD shift Core level shift Goodman and Rodriguez, Science279 (1992) 897 Descriptors from spectroscopy

23. Cu/MgO Ag/MgO Pb/MgO Single crystal microcalorimerty Larsen, Starr, Campbell, Chem.Thermodyn. 33, 333 (2001) Brown, Kose, King, Chem. Rev. 98, 797 (1998).

24. Descriptors 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)

26. How 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)

27. Methane activation Transition state for CH4 dissociation on Ni(211) b Bengaard, Rostrup-Nielsen, Nørskov

28. Methane activation on Ni/Ru Egeberg, Chorkendorff, Catal. Lett. 77, 207 (2001)

29. Lessons from biology • Catalysis at ambient temperature and pressure • Extreme selectivity • Direct coupling of energy into the important reaction coordinate (non-thermal catalysis)

30. Nitrogenase 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)

31. N2 hydrogenation on FeMoco Rod, Nørskov JACS 122, 12751 (2000)

32. The 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)

33. Comparing the FeMoco and Ru(0001) Rod, Logadottir, Nørskov J.Chem.Phys. 112, 5343 (2000)

34. Status • 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!

35. Moving 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

36. Promoting development An integrated approach: Experiments, models Synthesis testing characterization Theory