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Nanostructuri catalitice continand metale nobile: sinteza, caracterizare si comportare catalitica

University of Bucharest Department of Chemical Technology and Catalysis. Nanostructuri catalitice continand metale nobile: sinteza, caracterizare si comportare catalitica. Vasile I. P ȃ rvu lescu.

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Nanostructuri catalitice continand metale nobile: sinteza, caracterizare si comportare catalitica

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  1. University of Bucharest Department of Chemical Technology and Catalysis Nanostructuri catalitice continand metale nobile: sinteza, caracterizare si comportare catalitica Vasile I. Pȃrvulescu Diaspora în cercetarea ştiinţifică şi învăţământul superior din România, Bucureşti, 21-24 septembrie 2010 Workshop Exploratoriu: "Nano Sisteme Dinamice: de la Concepte la Aplicatii Senzoristice"

  2. Size dependent properties of nanoparticles • magnetic • optical • melting points • specific heats • surface reactivity • CATALYTIC Ag(12nm) Au(100nm) Au(50nm) Ag(90nm) Ag(40nm) Colors of light scattered by solutions of nanoparticles of certain sizes

  3. Nanoscale Clusters/Particles 100-100,000 atoms 1-100 nm in diameter Condensed Matter Millions of atoms Solid State Physics Atoms/Molecules 1-10atoms Quantum Chemistry Novel Preparations Catalysis C-C coupling Aerobic oxidations Fuel cells Heterogeneous enantioselective Hydrogenations Size dependent properties of nanoparticles

  4. supported nano-structures structural embedded nano-structures textural embedded nano-structures

  5. Size controlled Nanoparticles in Heterogeneous catalysis Heterogeneous catalysts generally consist of a high surface area support material onto which an active component has been deposited. The anchoring of active component onto the support can be carried out via a number of methods such as homogeneous deposition precipitation, ion-exchange, chemical vapor deposition and (incipient) wetness impregnation. From an industrial point of view the latter type of technique is most often favored because of its technical simplicity, low amount of waste streams and low costs. This method is based on the incorporation of active component via impregnation of a solution containing a precursor, which is typically a metal salt. By applying thermal treatments the precursor is deposited onto the support and subsequently converted into the catalytic active species. The chemistry involved in impregnation is very complicated since many processes take place during the impregnation, drying and activation steps. It is a well-known fact that the properties of the precursor solution (e.g. type of metal salt and pH) and support (e.g. texture and surface reactivity) largely affect the final composition of the catalyst. However, still little is known about the separate influences of precursor and support on the impregnation, drying and activation processes.

  6. Size controlled Nanoparticles in Heterogeneous catalysis Ionic exchange Materials: acidic (zeolites, clays), basic (LDH)

  7. Size controlled Nanoparticles in Heterogeneous catalysis Deposition-precipitation Materials: a very large variety including nano- and bulk materials, porous and non-porous supports

  8. H+ H+ H+ Beta zeolite Ir(acac)3] + O HO O O H+ Ir OH O Ir Ir(acac)3] HO Ir Ir O O H+ H+ O O Beta zeolite Beta zeolite -Hacac 300 oC 300 oC O Ir (acac)2 O Ir (OH)2 H+ H+ H+ H+ H+ H+ Beta zeolite Beta zeolite … Ionic exchange: low metal loading iridium catalysts

  9. 1.0% Ir/BEA 2.0% Ir/BEA 3.0% Ir/BEA 5.0% Ir/BEA IrOx IrOx Ir0 Ir0 flowing H2 at 250 or 450°C O Ir HO HO O O O Ir Ir Ir OH OH Ir O Ir Ir HO HO Ir Ir Ir Ir O O O O H+ H+ H+ H+ H+ H+ H+ O O O O Beta zeolite Beta zeolite Beta zeolite Catalysts preparation The deposition of iridium on BETA zeolite involves succesive ion-exchange and condensation processes. The generation of new protons is also possible.

  10. H+ H+ H+ Ir0 Ir0 IrOx OH- OH- OH- H+ H+ H+ H+ H+ IrOx HO- HO- Ir0 Catalytic reaction: synthesis of prostaglandin derivatives Angew. Chem., Int. Ed. Engl., 115 (2003) 5491-5494.

  11. Hydrogenation of enones

  12. H+ H+ Ir0 H+ Ir0 IrOx Temperature reduction Nature of the support OH- OH- OH- H+ H+ H+ H+ Optimal catalyst H+ IrOx HO- Support calcination HO- Iridium loading, %wt Ir0 Optimal catalyst BEA zeolite 450oC 1% Ir NON PRECALCINED Angew. Chem., Int. Ed. Engl., 115 (2003) 5491-5494.

  13. Why 1% Ir/beta????????

  14. CatalystReduction temperature 250oC450oC Reduction H2 up-take,Metal ReductionH2 up-take,Metal degree,%cm3 g-1dispersion,%degree,%cm3 g-1dispersion, % 1%Ir/BEA 140.0318.2250.0517.1 2%Ir/BEA 270.058.6380.078.1 3%Ir/BEA 580.083.9670.083.4 5%Ir/Beta690.123.1810.112.4 1%Ir/Beta-514 0.03 19.224 0.05 18.3 2%Ir/Beta-5 24 0.05 9.6 36 0.08 9.2 3%Ir/BEA-500 54 0.10 5.566 0.11 4.9 5%Ir/Beta-5 670.18 4.7 77 0.18 4.1 1%Ir/Beta-713 0.03 19.521 0.05 19.8 2%Ir/Beta-7 23 0.06 11.7 35 0.09 10.8 3%Ir/Beta-7 50 0.13 7.562 0.14 6.5 5%Ir/Beta-7630.25 6.8 73 0.26 6.0 Reduction degree, hydrogen up-take and Ir dispersion on beta-zeolites

  15. 185 oC 1wt% Ir/beta 116 oC 209 oC Reduction degree, hydrogen up-take and Ir dispersion on beta-zeolites CatalystReductionH2 up-take, Metal degree, % cm3 g-1dispersion,% 1%Ir/MCM-41360.1433.4 2%Ir/MCM-41480.1614.6 3%Ir/MCM-41750.259.4 5%Ir/MCM-41890.34 6.5 1%Ir/SiO2370.049.4 2%Ir/SiO2460.054.3 3%Ir/SiO2770.07 2.6 5%Ir/SiO2880.091.7 1%Ir/ZrO2290.026.8 2%Ir/ZrO2440.043.8 3%Ir/ZrO2710.052.2 5%Ir/ZrO2850.07 1.4 1wt% Ir/MCM-41 110 oC 250 oC 85 oC 53 oC 3wt% Ir/SiO2 113 oC

  16. XPS Binding energies, and Iro/Irn+ and Ir/Si(Zr) ratios CatalystBinding energy of Iro/Irn+Binding energy, Comparative Ir levels, eV ratio eV Ir/Si ratios x 103 Ir0 Irn+Si 2pAl 2pO1sAnalytic XPS Ir4f7/2 Ir4f5/2 Ir4f7/2 Ir4f5/2 1%Ir/BEA61.4 64.6 63.2 65.4 0.42 103.574.8532.83.3 6.0 1%Ir/BEA** 61.5 64.7 63.3 65.5 0.38103.574.8532.83.36.2 1%Ir/BEA***61.5 64.7 63.3 65.5 0.31103.574.8532.83.35.9 2%Ir/BEA 61.2 64.4 63.0 65.0 1.02103.674.8532.86.611.2 3%Ir/BEA 61.2 64.2 62.7 65.1 1.70103.674.6532.89.920.6 5%Ir/BEA 61.2 64.3 62.6 65.2 1.47103.674.7532.816.542.1 1%Ir/MCM-4161.2 64.4 62.5 65.0 1.71103.8-533.03.12.5 1%Ir/SiO2 61.5 64.6 62.5 65.3 1.68103.7-532.89.620.0 1%Ir/ZrO2* 61.7 64.8 62.3 65.2 0.31-*-531.96.440.0 Ir/Zr: *-The binding energy of Zr3d: 182.2 eV; **-zeolite precalcined at 700 oC; ***- catalyst reduced at 250 oC.

  17. 193Ir Mossbauer spectrum 1%Ir/beta 100 Relative transmission, % IrO2 99.9 -50 5 Velocity, mm s-1

  18. Py-B Py-L Py-B Py-L A.U. • 1450 1500 1550 1600 1650 1700 • Wavenumber, cm-1 Py-FT-IR Desorption temperature: 200 oC The new band at 1453 cm-1 may suggest either the existence of a new Lewis site (Irn+) or the re-adsorption of Py via H bonds forming Py-H species (also assigned to the presence of Ir).

  19. -20 BEA zeolite calcined at 7000C 0 20 40 60 80 Octa-Al Octa-Al 100 • 80 60 40 20 0 -20 -40 -60 • ppm Tetra-Al Distored tetra-Al BEA zeolite uncalcined CP/MAS 27Al-NMR

  20. Lewis acid centers: H+ H+ H+ Al3+ (Ir3+) + H2 H+ + H- Ir0 Ir0 Ir0 IrOx OH- Metallic centers: OH- H+ H- H+ H+ R’ H C=O 12 13 H+ O H H+ HO- H O O HO- IrOx (mCl) R' = OC H H 4 6 C R’ 12 13 O H OH H H O O Ir0 Reactionmechanism Cram-chelate rule Angew. Chem., Int. Ed. Engl., 115 (2003) 5491-5494.

  21. Effect of the particle size: Synthesis of menthols from citronellal Chem. Commun., (2004) 1292-1293.

  22. Influence of the metal loading and support Ir/NaBeta25S Ir/HBeta25 Reaction conditions: 0.8 MPa H2, 80°C, cyclohexane, 10h Citronellal hydrogenation No menthol Chem. Commun., (2004) 1292-1293.

  23. Influence of Ir and of the support Reaction conditions: 80°C, cyclohexane Citronellal isomerization Chem. Commun., (2004) 1292-1293.

  24. XPS Binding energies, and Iro/Irn+ and Ir/Si(Zr) ratios CatalystBinding energy of Iro/Irn+Binding energy, Comparative Ir levels, eV ratio eV Ir/Si ratios x 103 Ir0 Irn+Si 2pAl 2pO1sAnalytic XPS Ir4f7/2 Ir4f5/2 Ir4f7/2 Ir4f5/2 1%Ir/BEA 61.4 64.6 63.2 65.4 0.56103.574.8532.83.36.0 2%Ir/BEA 61.2 64.4 63.0 65.0 1.26103.674.8532.86.611.2 3%Ir/BEAS5 61.2 64.2 62.7 65.1 1.68103.674.6532.89.920.6 3%Ir/BEA-S61.2 64.2 62.7 65.1 1.70103.674.6532.89.920.6 5%Ir/BEA 61.2 64.3 62.6 65.2 1.84103.674.7532.816.542.1 Chem. Commun., (2004) 1292-1293.

  25. Fourier transforms of EXAFS Chem. Commun., (2004) 1292-1293.

  26. HRTEM- 1% Ir/Na-BEA-S

  27. HRTEM- 3% Ir/Na-BEA-S

  28. Deposition-precipitation

  29. Au How the story starts? Echavarren suggested that gold could be an efficient catalyst for coupling reactions C. Nieto-Oberhuber, S. Lopez, A. M. Echavarren,J. Am. Chem. Soc. 127 (2005) 6178

  30. Why not to use gold for cycloisomerisation reactions to obtain heterocycles?

  31. What kind of heterocycles? A lactone is a cyclic ester in organic chemistry … and it is the condensation product of an alcohol group and a carboxylic acid group in the same molecule.

  32. are present in many components of essential oils Unsaturated γ-lactone rings is a carbohydrate lactone vitamin C is found in oak trees, and impart flavor to whisky whisky lactone Importance of lactones Lactones are found in various forms in numerous naturally occurring compounds.

  33. Conditions: elevated temperatures additives or ligands or/and strong base refluxing solvents How they have been synthesized? • by conventional Lewis acids • toxic Hg salts • Pd, Ru, Rh, Ni, Ag, Zn Why we should use gold? - mild conditions, no additives

  34. Unsubstituted substrate Gold homogeneous catalysis Conditions: 10 mol% AuCl acetonitrile RT, 1h K2CO3 H. Harkat, J.-M. Weibel, P. Pale, Tetrahedron Letters, 2006, 47, 6273

  35. Substituted substrate Gold homogeneous catalysis Conditions: 5 mol% AuCl or AuCl3 No use of a base acetonitrile RT, 2h E. Genin, P. Y. Toullec, S. Antoniotti, C. Brancour, J.-P. Genet, V. Michelet, JACS, 2006, 128, 3112

  36. Gold homogeneous catalysis Conditions: 5 mol% AuCl or AuCl3 No use of a base acetonitrile RT, 2h E. Genin, P. Y. Toullec, S. Antoniotti, C. Brancour, J.-P. Genet, V. Michelet, JACS, 2006, 128, 3112

  37. + AuCl or AuCl3 ZSM-5 or Beta zeolite ? Heterogeneization by gold- ionic exchange? 0% conversion 0% conversion

  38. Na+ Na+ Na+ Na+ Na+ Na+ OH- OH- OH- OH- OH- OH- OH- OH- OH- OH- OH- OH- NaOH 1M mixing solutions under stirring Cl- Cl- Cl- Cl- Cl- Cl- Au3+ Au3+ Au3+ Au3+ Au3+ Au3+ HAuCl4 solution, 70°C How heterogenize the gold system? Chem. Eur. J. 14 (2008) 9412-9418.

  39. Particles size distribution? Adding the support to the mixed solution Beta zeolite CeO2 MgO TiO2 Stirring for 4h Washing, filtration, drying A. Corma, P. Serna, Science 2006, 313, 332 and references herein S. Carrettin, J. Guzman, A. Corma Angew. Chem. Int. Ed. 2005, 44, 2242-2245 How heterogenize the gold system?

  40. Catalytic tests Gold catalyst, CH3CN 8h, RT-40°C Conversion Isolated yield 0% / Au/CeO2 0% / Au/MgO Substituted acetylenic acid, reactive 50% 25% Au/TiO2 100% Au/Beta zeolite 99% Chem. Eur. J. 14 (2008) 9412-9418.

  41. TEM images and EDX analysis of Au/zeolite beta quite narrow size distribution 3-4 nm Beta zeolite F. Neaţu, Z. Li, R. Richards, P. Y. Toullec, J.-P. Genêt, K. Dumbuya, J. M. Gottfried, H.-P. Steinrück, V. I. Pârvulescu, V. Michelet, Chem. Eur. J. 14 (2008) 9412-9418.

  42. TEM images and EDX analysis of Au/MgO structural non-uniformities 3-12 nm MgO Chem. Eur. J.14 (2008) 9412-9418.

  43. Surface area and average particle size of supported catalysts *measured from TEM Chem. Eur. J.14 (2008) 9412-9418

  44. Substituted acetylenic acid Au/Beta zeolite Catalytic tests 40°C 80% (100%) 85% (100%) 71% (100%) 88% (100%) Very good results, comparable with the results obtained in homogeneous catalysis. RT 60% (90%) 65% (70%) Performing the reaction at room temperature corresponded to smaller reaction rates Yield% (Conv.%) Chem. Eur. J.14 (2008) 9412-9418

  45. AuCl3, without base, homogeneous catalysis Unsubstituted acetylenic acid Catalytic tests 40°C 0% (0%) 0% (0%) RT 0% (0%) 0% (0%) NO REACTION Yield% (Conv.%) V.I. Pârvulescu et al.,Chem. Eur. J.14 (2008) 9412-9418

  46. Possible decomposition of the product Au/Beta zeolite Catalytic tests Unsubstituted acetylenic acid 40°C 50% (100%) 80% (85%) RT 25% (40%) 12% (30%) Performing the reaction at room temperature corresponded to smaller reaction rates Yield% (Conv.%) Chem. Eur. J.14 (2008) 9412-9418

  47. Beta zeolite ? Oxidation state? Performing the reaction in ARGON atmosphere gave much LOWER results then performing reaction in AIR. WHY?

  48. Au in reduced state (Au I) In-situ high-pressure XPS of the Au/beta catalyst Argon 84.0 eV 85.0 eV Chem. Eur. J.14 (2008) 9412-9418

  49. Au in reduced state (Au I) In-situ high-pressure XPS of the Au/beta catalyst • No change observed when using a reducing species- like CO • Even the initial sample was preserved in atmosphere conditions, the gold was reduced in the vacuum chamber of the XPS. • No further reduction of Au(I) to Au (0) in the presence of CO, could be due to the Au species is incorporated into the zeolite framework. 85.0 eV CO 84.0 eV

  50. Au in oxidized state (Au III) Au in reduced state (Au I) In-situ high-pressure XPS of the Au/beta catalyst Oxygen 85.6 eV 85.0 eV The reduction of the active site Au(III) to Au(I) in the presence of the acetylenic acid substrate is leading to inactive catalysts. The role of air is to reoxidize the inactive site Au(I) to the active site Au(III). Chem. Eur. J.14 (2008) 9412-9418

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