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D. Bazin

Laboratoire de Physique de la Matière Condensée Laboratoire mixte de l’école Polytechnique et du CNRS (UMR 7643) 3 Novembre 2005. L’interaction Agrégat métallique - Molécule au cœur des processus physicochimiques environnementaux. D. Bazin. NO. NO. NO. O2. NO. O2. HC. MonoMet. Bimet.

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D. Bazin

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  1. Laboratoire de Physique de la Matière Condensée Laboratoire mixte de l’école Polytechnique et du CNRS (UMR 7643) 3 Novembre 2005 L’interaction Agrégat métallique - Molécule au cœur des processus physicochimiques environnementaux D. Bazin

  2. NO NO NO O2 NO O2 HC MonoMet Bimet MonoMet MonoMet II Objectiv of the lecture Nanoscience Surface Science Cluster Behaviour Adsorption Mode Heterogeneous Catalysis

  3. PLAN I. X-ray Absorption Spectroscopy II. Interaction between nanometer scale metallic cluster & NO

  4. Exafs I0 S I1 E 2p3/2 Xanes 2p1/2 Xas 2s 1s I I.1 X-ray Absorption Spectroscopy x(E) log Sayers, D. A., Lytle F. W. and Stern E. A., Advances in X-ray Analysis, (Ed. Plenum, New-York, 13, 1970).

  5. Structural terms Nj , Rj , j. Electronic terms fj(k), j(k), I I.1 The associated formula (k) =jNj/kRj2 fj(k)exp(-Rj/)exp(-2j2k2)sin(2kRj +j(k))

  6. I I.2 Nanometer scale metallic cluster & Xas • D. Bazin, D. Sayers, J. Rehr, Comparison between Xas, Awaxs, Asaxs & Dafs applied to nanometer scale metallic clusters. J. Phys. Chem. B 101, 11040 (1997). • D. Bazin, D. Sayers, J. Rehr, C. Mottet Numerical simulation of the Pt LIII edge white line relative to nanometer scale clusters, J. of Phys. Chem. B 101, 5332 (1997). • D. Bazin, J. Rehr, Limits and advantages of X-ray absorption near edge structure for nanometer scale metallic clusters. J. Phys. Chem. B 107, 12398 (2003).

  7. Impregnation Cl Pt O Calcination Pt O O O Pt Pt Reduction Pt Pt Pt Pt Pt I 1%wt Pt/oxide I.3 Some examples • Xas studies of bimetallic Pt-Re(Rh)/Al2O3 catalysts in the first stages of preparation. • D. Bazin et al., J. of Cat. 110, 209 (1988). • Bimetallic reforming catalysts : Xas of the particle growing process during the reduction. • D. Bazin et al., J. Cat. 123, 86 (1990). • In situ high temperature and high pressure Exafs studies of Pt/ Al2O3 catalysts : Part I. • N. S. Guyot-Sionnest et al., Cat. Let 8, 283 (1991). • In situ high temperature and high pressure Exafs studies of Pt/ Al2O3 catalysts : Part II. • N. S. Guyot-Sionnest et al., Cat. Let 8, 297 (1991). • Investigation of dispersion and localisation of Pt species in mazzite using Exafs. A. Khodakov et al. J. of Phys. Chem. 101, 766 (1996). • In situ study by Xas of the sulfuration of industrial catalysts : the Pt & PtRe/Al2O3 system. A. Bensaddik et al., Applied Cat. A 162, 171, (1997). • Xas of electronic state correlations during the reduction of the bimetallic PtRe/Al2O3 system. • D. Bazin et al., J. of Synchrotron Radiation 6, 465, 1999. • Influence of the H2S/H2 ratio and the temperature on the local order of Pd atoms in the case of a highly dispersed multimetallic catalyst : Pd-Ni-Mo/Al2O3. • D. Bazin et al., J. de Physique IV, 12-6, 379, (2002). • Structure & size of bimetallic PtPd clusters in an hydrotreatment catalyst. • D. Bazin et al., Accepted in Oil & Gas Science and Technology – Rev. IFP PtRe & PtRh genesis T&P H2S Real time Reforming …Pt, PtPd, PtRh, PtMo,PtSn,PtRe, PtIr, Fischer–Tropsch, Co, CoPt, CoPd, CoRu,

  8. Anomalous Diffraction 3d L edge N K edge Real time J.D. Grunwaldt et al., J. of Cat. 213,291 (2003) L. Drozdova et al. J. Phys. Chem. B 106,2240 (2002) NO MonoMet I I.4 Nanometer scale metallic cluster & R.S. • Comparison between Xas & Awaxs applied to monometallic clusters. D. Bazin, D. Sayers, Jpn J. Appl. Phys. 32-2, 249, 1993. • Comparison between Xas & Awaxs applied to bimetallic clusters.D. Bazin, D. Sayers, Jpn J. Appl. Phys. 32-2, 252, 1993. • AWAXS in heterogeneous catalysisD. Bazin, L. Guczi, J. Lynch, App. Cat. A 226, 87, 2002. • Real time in situ Xanes approach to characterise electronic state of nanometer scale entities D. Bazin, L. Guczi, J. Lynch, Rec. Res. Dev. Phys. Chem. 4, 259, 2000. • Soft X-ray absorption spectroscopy and heterogeneous catalysis. D. Bazin, L. Guczi, App. Cat. A 213/2, 147, 2001. • New opportunities to understand heterogeneous catalysis processes through S.R. studies and theoretical calculations of density of states : The case of nanometer scale bimetallic particles D. Bazin, C. Mottet, G. Treglia, Applied Catalysis A (1-2), 47-54, 2000. • New trends in heterogeneous catalysis processes on metallic clusters from S.R. & theoretical studies D. Bazin, C. Mottet, G. Treglia, J. Lynch, Applied Surf. Sci. 164, 140, 2000.

  9. II II. Catalyse DeNOx II.1 Introduction II.2 Behaviours of the metallic clusters Ex : NO/Pt II.3 NO adsorption on metallic surface II.4 NO adsorption on metalic clusters (Ru & Pt) II.5 Remarks from Prof. J. Friedel II.6 Other experimental results Ir,Rh,Cu,Pt,Pd II.7 Discussion : Support, Preparation, Cluster size, Temp. II.8 Some explanations II.9 Mechanisms Pt,Cu,Rh,Ru,Ir II.10 CO on metallic surface II.11 A bridge between surface science and nanoscience : Implications in heterogeneous catalysis : How to select a catalyst Nanoscience Surface Science Heterogeneous catalysis LMSPC

  10. LMSPC Pt/Rh Ceria Alumina II II.1 Introduction The Goal : To obtain CO2 and N2 from CO and NOx

  11. LMSPC II Pt, Rh, CeO2, Al2O3 PtRh Pt : CO+1/2O2__>CO2& HC + O2__> CO2 + H2O Rh NO+CO__>1/2 N2+CO2&NO+H2__>1/2N2+H2O CeO2 : Oxygen (Ce3+ ____>Ce4+) Al2O3: High specific surface (>200m2/g)

  12. NO Fragmentation Pt Sintering Faceting Initial state II II.2 Behaviours of the metallic clusters Ex : NO/Pt D. Bazin, L. Guczi, , Recent Res. Dev. Phys. Chem. 3, 387, 1999. D. Bazin, C. Mottet, G. Treglia, J. Lynch, Applied Surf. Sci. 164, 140, 2000.

  13. NO Pt Initial state Nanoscience NO/Pt Experimental data

  14. II Surface science II.3 NO adsorption on metallic surface In particularly, in the case of NO, we can distinguish metals for which there is dissociative chemisorption and those for which molecular chemisorption occurs. Ability of transition metal surface to dissociate the NO molecule from G. Broden et al. Sc Ti V Cr Mn Fe Co Ni Cu Y Zr Nb Mo Tc Ru Rh PdAg Lu Hf Ta W Re Os Ir PtAu Metals which are associated with a molecular chemisorption are in red style, the others give rise to a dissociative chemisorption. G. Broden et al. Surf. Sci. 59, 593 (1976).

  15. Surface Science II More recently, W. A. Brown and D. A. King suggest a correlation between the propensity for dissociation of the NO monomer at low coverage and the melting points of the transition metals. • The melting points are a direct measure of the cohesive energies of the elements. • The higher the metal cohesive energy, the greater is the propensity for NO dissociation. W. A. Brown , D. A King. J. Phys. Chem. B, 104, 2581 ( 2000).

  16. Initial state NO Met Ru Pt Oxidation of the cluster Sintering of the cluster NO adsorption induces a sintering of the Pt clusters deposited on g-Al2O3 . P. Lööf et al., J. Catal. 144 (1993) 60. S. Schneider et al., App. Cat. 189, 139 (1999). In the case of Ru, the adsorption of NO leads to break up the metallic cluster T. Hashimoto et al., Physica B 208& 209, 683 (1995). II nanoscience II.4 NO adsorption on metalic clusters (Ru & Pt)

  17. Ru Oxidation of the cluster Surface Sintering of the cluster Pt II Correlation adsorption mode & cluster behaviour ? Cluster Cluster D. Bazin, Topics in Catalysis 18(1), 79, 2002.

  18. II II.5 Remarks from Prof. J. Friedel

  19. Ir II II.6 Other experimental results Ir,Rh,Cu,Pt, Pd At 500°C, almost all NO in contact with Ir0 was decomposed to N2 and oxidized Ir0 to IrO2 . C. Wögerbauer, et al.J. of Catalysis, 205, 157-167 (2002).

  20. Rh II II.6 Other experimental results Ir,Rh,Cu,Pt, Pd • Examination of the effects of the individual gases showed that NO alone disperses Rh over the SiO2 K. R. Krause et al. J. of Catalysis, 140 (1993) 424. • In the initial state, the environment of Rh atoms is NRhRh= 8 @ 2.68Å. After exposure to 4%NO/He at 313K for 5 s, NRhRh has significantly decreased (NRhRh=2). Note the presence of N (NRhN=1@1.78Å) & O (NRhO=2 @2.05Å). T. Campbell et al. Chem. Comm. 304-305 (2002) Surface studies of supported model catalysts Surface Science Reports 31 (1998) 231-325 Claude R. Henry

  21. Cu II II.6 Other experimental results Ir,Rh, Cu, Pt, Pd The adsorption and reaction of NO on Cu clusters deposited on a 5 Å thick Al2O3 film shows strong similarities to its behaviour on Cu single crystals. The STM results show that the Cu clusters grow according to the Volmer-Weber mechanism. Nitric oxide reduction by Cu nanoclusters supported on thin Al2O3 films J. of Catalysis, Volume 22 ( 2004) 204. S. Haq, A. Carew and R. Raval

  22. Pt II II.6 Other experimental results Ir,Rh, Cu, Pt, Pd X. Wang et al. Cat.Today 96 (2004) 11-20.

  23. In Xafs of the Pd/MgO catalyst indicates that neither Pd oxidation nor particle sintering occurs during heating in flowing 1%/NO/He to 300°C. II II.6 Other experimental results Ir,Rh,Cu,Pt,Pd Pd(110) Pd(100) Pd(111)

  24. Ru Rh Ir Oxidation of the cluster Cu Sintering of the cluster Pt II II.7 Discussion • Discussion • Nature of the support • Preparation procedure • Cluster size • Temperature Combining Solid State Physics Concepts & X-Ray Absorption Spectroscopy to understand heterogeneous catalysis, D. Bazin, D. Sayers, J. Lynch, L. Guczi, G. Treglia, C. Mottet

  25. Support Ru/g-Al2O3 Ir/ Rh/g-Al2O3, ZrO2, CeO2 Cu/Al2O3 Pt/ SiO2, Al2O3 Precursor Ru3(CO)12 IrCl3(H2O)3, Ir(NH3)xCl3(H2O)y RhCl(CO)2/g-Al2O3 Cu : Evaporation H2PtCl6 Pt(NH3)4(OH)2 II II.7 Discussion : Support, Preparation, Cluster size, Temp.

  26. II II.7 Discussion : Support, Preparation, Temp., Cluster size Effect on the NO adsorption mode Rh NO adsorbs molecularly on Rh at low temperatures and dissociatively at higher temperatures. On Rh[100], molecular NO dominates upon adsorption at 100K, but heating leads to N2 and O2 production in TPD, suggesting dissociation. Ni molecular adsorption takes place on Ni at low temperature and at higher temperatures both molecular and dissociative adsorption are observed.

  27. Rh II II.7 Discussion : Support, Preparation, Temp., Cluster size

  28. II Preliminary conclusion • Discussion • Nature of the support • Preparation procedure • Cluster size • Temperature • Pressure • Cluster morphology

  29. How change the Brown diagram when we consider not metallic surface but metallic cluster ? II II.8 Some explanations : Cohesion energy As it can be seen, a significant decrease of the cohesive energy, around 30%, is observed independently the nature of the metal and the morphology of the cluster [a-c]. [a] A. Khoutami, PhD thesis, Paris XI University (1993). [b] F. Baletto et al., Phys. Rev. Let. 84, 5544 (2000). [c] R. A. Guirado-Lopez, PhD thesis, Paris XI University (1999).

  30. II II.8 Some explanations : Validity of the straight line Dissociative chemisorption is the most stable situation / Eads(N)/ + / Eads(O)/ > Edis(NO) + /Eads(NO)/ these adsorption energies are more important for metals which are at the middle of the transition series, metals for which we observed here a dissociative adsorption.

  31. Initial state Sintering of the cluster High coverage regime Pt & Cu II II.9 Mechanisms Pt,Cu,Rh,Ru,Ir High temperature Mobility & Decompostion of the nitrosyl species

  32. II.9 Mechanisms Pt,Cu,Rh,Ru,Ir Initial state Oxidation of the cluster II Rh & Ru & Ir N2 desorption High temperature Decomposition process

  33. II Other molecules / Eads(N)/ + / Eads(O)/ > Edis(NO) + /Eads(NO)/ Sc Ti V Cr Mn Fe Co Ni Cu Y Zr Nb Mo Tc Ru Rh Pd Ag Lu Hf Ta W Re Os Ir Pt Au NO : 6.50 eV Sc Ti V Cr Mn Fe Co Ni Cu Y Zr Nb Mo Tc Ru Rh Pd Ag Lu Hf Ta W Re Os Ir Pt Au N2: 9.76 eV O2 : 5.12 eV, N2O : 4.4 eV

  34. Ability of transition metal surface to dissociate the CO molecule from R.B. Anderson Sc Ti V Cr Mn Fe Co Ni Cu Y Zr Nb Mo Tc Ru Rh Pd Ag Lu Hf Ta W Re Os Ir Pt Au Dissociativ Non-Dissociativ T=200°C-300°C T=20°C II II.10 CO on metallic surface In particularly, in the case of CO, we can distinguish metals for which there is dissociative chemisorption and those for which molecular chemisorption occurs. CO: 11.09 eV R.B. Anderson ”The fischer-Tropsch Synthesis”, Chap 4, Academic press, New York, 1984

  35. CO NonDissociativ Adsorption NanoMet High coverage Initial state High Temperature II II.10 Behaviours of the metallic cluster On Pt clusters, A. Berko et al. [1] found that CO adsorption induces a significant increase in the initial size of the Pt nanoparticles of 1–2 nm even at room temperature. This agglomeration preceded by disruption of the smaller Pt nanoclusters at lower CO pressures is explained by CO-assisted Ostwald ripening, in which the mass transport proceeds via surface carbonyl intermediates. Similar results have been obtained in the case of Ru [2], Rh[3,4], Cu[5] and Pd [6,7]. [1] A. Berko et al. Surface Science 566568, 337 (2004). [2] T. Mizushima et al. J. Phys. Chem. 94, 4980 (1990). [3] H. F. J. Van't Blik et al. J. Phys. Chem. 87, 2264 (1983). [4] A. Suzuki et al. Angew. Chem. Int. Ed., 42, 4795 (2003). [5] X. Wang et al. J. Phys. Chem. B 2004, 108, 13667. [6] S. L. Anderson et al. J. Phys. Chem., 95, 6603(1991) [7] W. Vogel et al. J. Phys. Chem. B 102, 1750 (1998). For all these metals, we are in the case of a non dissociative adsorption mode and it seems that the structural evolution of the nanometer scale metallic atoms follows the same scheme. Based on all these experimental facts, we can suppose that CO adsorption leads to a disruption of metal-metal atoms and to the formation of Metal-(CO)n species. Then, metallic clusters can be observed and as supposed in the case of Pt, mass transport proceeds via surface carbonyl intermediates. This general schema is quite close to the one proposed in the case of NO adsorption process.

  36. CO NanoMet Dissociativ Adsorption Initial state II II.10 Behaviours of the metallic cluster What happens if we consider metals which displays a dissociative adsorption mode? A beginning of the answer is given by the study performed by O. Ducreux et al. [1] on the Co/Al2O3 system. Through in situ X-ray diffraction experiments, the formation of a carbide is pointed out. [1]O. Ducreux, PhD Thesis, University Paris VI, 1999. Boudouard reaction 2CO --> Cads+CO2

  37. NO NO NO O2 NO O2 HC MonoMet Bimet MonoMet MonoMet II II.11 A bridge between surface science and nanoscience Cluster Behaviour Adsorption Mode Surface Science Nanoscience Heterogeneous Catalysis

  38. Rh Ir Ru Pd NO Pt Cu MonoMet II II.11athe metal-support interaction ? the metal-support interaction ? • As we have seen the relationship we have proposed between the adsorption mode of NO and the behaviour of the metallic cluster seems to be independant of the nature of the support, except for Pd. • For this metal, a great difference exists between MgO and CeO2. We have linked this dependency to the position of the metal versus the line which separates the two adsorption modes. • If this assumption is correct, such dependency is not so significant for other metals such Rh or Pt.

  39. Rh Ir Ru NO N2 Pt Cu MonoMet NO t II II.11b NO on monometallic cluster Catalytic activity of metallic clusters ? • For metals above the stability line, NO adsorption leads to the formation of a metal oxide. Thus, the catalytic activity tends to decrease. • For metals below the line, large metallic clusters are finally generated and evolution of the catalytic activity will follow these structural modifications.

  40. RuRh RuIr RuIr PtCu NO N2 PtRh PtRu PtPd Bimet NO PtIr Al2O3 CeO2 t PtPd II II.11c Bimetallic systems This simple model leads to a complete rejection of some bimetallic systems. For example, if we consider a RhRu bimetallic cluster, the NO adsorption process conducts to the formation of a metal oxide i.e. the dissociation of NO will stop. At the opposite, if we consider a PtCu bimetallic system, the NO adsorption will lead to some large clusters. • A guideline for the choice of bimetallic systems is to add to Pt (or Cu) a second metal such Rh, Ru or Ir. If we consider the CeO2 support, the PtPd bimetallic seems to be acceptable while the PtPd bimetallic system supported on alumina has to be rejected.

  41. Rh Ir Ru NO NO O2 O2 NO O2 HC Pt Cu MonoMet MonoMet MonoMet II II.11da mixture of NO+O2 • For metals above the stability line, NO adsorption leads to the formation of a metal oxide. The presence of O2 will not change significantly this simple scheme. For these metals, it is necessary to add to a NO+O2 mixing, a reductor agent in order to retablish the metallic state of the atoms. • Thus, the presence of NO allowed the Pt particles to conserve a metallic character. In this case, we can probably play with the relative concentration of the two gases NO and O2 to keep a metallic state.

  42. II • Nature of the support • Preparation procedure • Cluster size • Temperature II.12Conclusion & Perspectives D. Bazin, (2003) Solid State Physics and Synchrotron Radiation Techniques to Understand Heterogeneous Catalysis in nanotechnology, Ed. G.A. Somorjai, S. Hermans, B. Zhou. D. Bazin, J. Lynch, M. Ramos-Fernandez, X-ray absorption spectroscopy and Anomalous Wide Angle X-ray Scattering Two basic tools in heterogeneous catalysis, Oil & Gas Science and Technology – Rev. IFP, 58 (2003), No. 6, pp. 667-683 Séminaires 7 Avril 2005 : Modélisation de l’interaction entre le monoxyde d’azote et un agrégat métallique de dimension nanométrique, Centre de Recherche en Matière Condensée et Nanosciences, Marseille, France 11 Avril 2005 : L’interaction Agrégat métallique - Molécule au cœur des processus physico-chimiques environnementaux, Laboratoire de Chimie Théorique, Ivry sur Seine, France 20 Avril 2005 : L’interaction Agrégat métallique - Molécule au cœur des processus physico-chimiques environnementaux, Groupe de Physique des solides (GPS), Paris, France CO N2O

  43. II.13 Remarks from Prof. J. Friedel

  44. II.12 Conclusion & Perspectives Surface Science Nanoscience Heterogeneous Catalysis Structural Characterization @ the atomic scale Catalytic Activity

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