Surface Science &catalysis                                                    Cardiff Catalysis InstituteA nanoscale persp...
Surface Science &    catalysis                                                                                        Card...
Surface Science &    catalysis                                                                Cardiff Catalysis Institute ...
Surface Science &catalysis                                                    Cardiff Catalysis Institute    Preparation o...
Surface Science &      catalysis                                                                          Cardiff Catalysi...
Surface Science &catalysis                                        Cardiff Catalysis Institute                    Carbon su...
Surface Science &catalysis                                                         Cardiff Catalysis Institute            ...
Surface Science &catalysis                                                            Cardiff Catalysis Institute         ...
Surface Science & catalysis                                            Cardiff Catalysis Institute                     Con...
Surface Science &catalysis                                            Cardiff Catalysis Institute       The effect of acid...
Surface Science &catalysis                                                             Cardiff Catalysis Institute        ...
Surface Science &catalysis                                                 Cardiff Catalysis Institute                    ...
Surface Science &catalysis                                                      Cardiff Catalysis Institute               ...
Surface Science &catalysis                                        Cardiff Catalysis Institute            Models to account...
Surface Science &catalysis                                   Cardiff Catalysis Institute                    XPS     HNO3  ...
Surface Science &catalysis                                          Cardiff Catalysis Institute                           ...
Surface Science &catalysis                                        Cardiff Catalysis Institute            Models to account...
Surface Science &  catalysis                                                    Cardiff Catalysis Institute               ...
Surface Science &catalysis                                          Cardiff Catalysis Institute                    Local d...
Surface Science &catalysis                                                            Cardiff Catalysis Institute    Gold ...
Surface Science &catalysis                                                          Cardiff Catalysis Institute          G...
Surface Science &catalysis                                             Cardiff Catalysis Institute       XPS of Gold on Ac...
Surface Science & catalysis                                                  Cardiff Catalysis Institute       Gold deposi...
Surface Science &   catalysis                       Cardiff Catalysis InstituteAu deposition on a HCl treated    surface  ...
Surface Science & catalysis                                                  Cardiff Catalysis Institute       Gold deposi...
Surface Science &   catalysis                                                            Cardiff Catalysis Institute      ...
Surface Science &catalysis                                                 Cardiff Catalysis Institute                    ...
Surface Science &  catalysis                                                                          Cardiff Catalysis In...
Surface Science &catalysis                                               Cardiff Catalysis Institute                    Fu...
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Nanoscale perspective on the effect of acid washing carbon catalyst supports

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Presented at the Dennis Dowden commemoration meeting in Durham, 3rd April, 2013

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Nanoscale perspective on the effect of acid washing carbon catalyst supports

  1. 1. Surface Science &catalysis Cardiff Catalysis InstituteA nanoscale perspective on the effect of acid washing of carbon catalyst supports Emir Bouleghlimat, Philip R. Davies, Robert J. Davies, Jiri Kulahvy, David J. Morgan Cardiff Catalysis Institute, School of Chemistry, Cardiff University Dennis Dowden Commemoration 3rd April 2013 1
  2. 2. Surface Science & catalysis Cardiff Catalysis Institute Selection of papers by DowdenTitle Journal YearCatalysis and the electronic-structure of solids Abstracts of American chemical society 1985Ammonia-synthesis and related reactions over iron-cobalt and iron- Applied catalysis 1982nickel alloy catalysts .1. Catalysts reduced at 853-KHydrogen spillover on alumina-supported Pt-Re catalysts JCS Chem Comm 1977Design of heterogeneous catalysts Chimica & lndustria 1973Crystal and ligand field models of solid catalysts Catalysis reviews 1971Principles for selection of catalyst carriers Chemie ingenieur technik 1968 Anales de la real sociedad espanola deSurface valencies chemisorption and catalysis fisica y quimica seria b-quimica 1965New ideas in catalysis Chemistry & industry 1962The selective hydrogenation of acetylene Transactions of the Faraday society 1958The significance of patterns of activity in chemisorption and catalysis Angewandte chemie 1958Hydrogen-deuterium exchange on the oxides of transition metals Advances in catalysis 1957The testing of heterogeneous catalysts Advances in catalysis 1957Heterogeneous catalysis .1. Theoretical basis Chemistry & industry 1949The heat of adsorption of gases on chromium sesquioxide at low J. Chem. Soc 1939pressures and room temperaturesHeats of adsorption of gases on chromic oxide at low temperatures JACS 1938 Dennis Dowden Commemoration 3rd April 2013 2
  3. 3. Surface Science & catalysis Cardiff Catalysis Institute Carbon as a Catalyst Support for Gold Hydrochlorination of ethyne Au/C C2H2 + HCl C2H3Cl Vinyl chloride PVC“Aqua regia …… prepare the most efficient catalysts for the hydrochorination of acetylene byimpregnation of HAuCl4 on carbon …….. due to a combination of the oxidising effect of HNO3on the carbon support and gold, as well as a nucleation effect of HCl …. the two acids ….. actsynergistically.”“Aqua Regia Activated Au/C Catalysts for the Hydrochlorination of Acetylene.”Marco Conte, Peter Johnston, Graham J. Hutchings et al.Journal of Catalysis 297 (2013) 128 Dennis Dowden Commemoration 3rd April 2013 3
  4. 4. Surface Science &catalysis Cardiff Catalysis Institute Preparation of Carbon Supported Metals 1. Washing: • HCl, HNO3, Aqua Regia (HCl & HNO3) 2. Impregnation • HAuCl4, H2PdCl4 and H2PtCl4 • H2O, HCl, HNO3, Aqua Regia 3. Drying • 290 oC - 200 oC 4. Regeneration • H2O, HCl, HNO3, Aqua Regia Dennis Dowden Commemoration 3rd April 2013 4
  5. 5. Surface Science & catalysis Cardiff Catalysis Institute Direct synthesis of H2O2“Switching Off Hydrogen Peroxide Hydrogenation in the Direct Synthesis Process.” Edwards, Hutchings et al. Science 323 (2009) 1037 Fig. 2. STEM-XEDS particle size distributions acid-pretreated and non treated catalysts.Table 2. Activity and selectivity of pretreated and untreated carbon-supported catalysts Dennis Dowden Commemoration 3rd April 2013 5
  6. 6. Surface Science &catalysis Cardiff Catalysis Institute Carbon supports Dennis Dowden Commemoration 3rd April 2013 6
  7. 7. Surface Science &catalysis Cardiff Catalysis Institute Nanoscale investigation: can we connect UHV and catalysis? HOPG “Bench top” surface science HOPG • Graphite crystal Catalyst • Preparation in air Surface Science• Carbon powder • Deposition from solution • Graphite crystal• Preparation in air • Surface science tools • UHV• Deposition from solution • Vapour deposition • Surface science tools Dennis Dowden Commemoration 3rd April 2013 7
  8. 8. Surface Science &catalysis Cardiff Catalysis Institute Experimental methods: Sample preparation: 1. Graphite peeled with sticky tape 2. Solutions added by dropper – 1 drop ~ 0.2ml 3. Allowed to stand in air 30 seconds 4. Dried in clean helium stream Spectroscopic & Microscopic methods Atomic Force X-ray photoelectron Scanning Tunnelling Microscopy spectroscopy Microscopy Dennis Dowden Commemoration 3rd April 2013 8
  9. 9. Surface Science & catalysis Cardiff Catalysis Institute Control experimentsClean HOPG surface Deionised water Ultra pure water Dennis Dowden Commemoration 3rd April 2013 9
  10. 10. Surface Science &catalysis Cardiff Catalysis Institute The effect of acid treatment on HOPGClean HOPG surface 0.2 M HCl, 30 min Dennis Dowden Commemoration 3rd April 2013 10
  11. 11. Surface Science &catalysis Cardiff Catalysis Institute Low concentration HCl0.2 M HCl, 30 min 0.1 M HCl, 30 min Surface coverage of features ~ 20% surface area Dennis Dowden Commemoration 3rd April 2013 11
  12. 12. Surface Science &catalysis Cardiff Catalysis Institute Comparison of HCl and HNO3: Effect of acid concentration 0.1 M HCl, 30 min 0.1 M HNO3, 30 min Dennis Dowden Commemoration 3rd April 2013 12
  13. 13. Surface Science &catalysis Cardiff Catalysis Institute Comparison of HCl and HNO3: Effect of acid concentration II 0.5 M HCl 10 M HCl 10 M 0.5 M x10 Dennis Dowden Commemoration 3rd April 2013 13
  14. 14. Surface Science &catalysis Cardiff Catalysis Institute Models to account for the features Dennis Dowden Commemoration 3rd April 2013 14
  15. 15. Surface Science &catalysis Cardiff Catalysis Institute XPS HNO3 HNO3 HCl HCl Clean Clean Dennis Dowden Commemoration 3rd April 2013 15
  16. 16. Surface Science &catalysis Cardiff Catalysis Institute XPS HNO3 HNO3 HCl HCl • No Ca, K, Na • Maximum O(a) ~ 4% monolayer Dennis Dowden Commemoration 3rd April 2013 16
  17. 17. Surface Science &catalysis Cardiff Catalysis Institute Models to account for the features Dennis Dowden Commemoration 3rd April 2013 17
  18. 18. Surface Science & catalysis Cardiff Catalysis Institute STM Clean graphite 0.1 M HCl treatedConclusion 0.1 M HCl treated 0.1 M HCl treated • The graphite lattice extends over the features • “Bubbles” not deposits Dennis Dowden Commemoration 3rd April 2013 18
  19. 19. Surface Science &catalysis Cardiff Catalysis Institute Local delamination HCl Dennis Dowden Commemoration 3rd April 2013 19
  20. 20. Surface Science &catalysis Cardiff Catalysis Institute Gold deposition on acid treated surfaces 6.2 x10-5 M HAuCl4 Sample preparation: 1. Clean graphite treated with 0.5 M HCl 2. 6x10-5 M HAuCl4 solution, 1 drop ~ 0.2ml 3. Stand 1 minute, blown dry in clean helium stream Gold “doughnuts”! Dennis Dowden Commemoration 3rd April 2013 20
  21. 21. Surface Science &catalysis Cardiff Catalysis Institute Gold nucleation on acid treated surfaces 0.5M HCl, 6.2 x10-6 M HAuCl4 Au 0.5M HCl HAuCl4 Au nucleation on acid induced defects HCl Dennis Dowden Commemoration 3rd April 2013 21
  22. 22. Surface Science &catalysis Cardiff Catalysis Institute XPS of Gold on Acid Treated Carbons • Auo dominates • % Auo/Au+/Au3+ similar • Au nucleation greater on HCl treated surface Dennis Dowden Commemoration 3rd April 2013 22
  23. 23. Surface Science & catalysis Cardiff Catalysis Institute Gold deposition on acid treated surfaces 6.2 x10-6 M HAuCl4HNO3 HCl HNO3 HClHNO3 HCl HCl HNO3 Dennis Dowden Commemoration 3rd April 2013 23
  24. 24. Surface Science & catalysis Cardiff Catalysis InstituteAu deposition on a HCl treated surface Dennis Dowden Commemoration 3rd April 2013 24
  25. 25. Surface Science & catalysis Cardiff Catalysis Institute Gold deposition on acid treated surfaces 6.2 x10-6 M HAuCl4HNO3 HCl HNO3 HClHNO3 HCl HCl HNO3 Dennis Dowden Commemoration 3rd April 2013 25
  26. 26. Surface Science & catalysis Cardiff Catalysis Institute Au deposition with an acidSample preparation: 1. Clean graphite 2. 6x10-6 M HAuCl4 solution in 0.5 M HCl or HNO3, 1 drop ~ 0.2ml 3. Stand 1 minute, blown dry in clean helium stream HNO3 HCl HNO3 dosed with Au HCl dosed with Au Dennis Dowden Commemoration 3rd April 2013 26
  27. 27. Surface Science &catalysis Cardiff Catalysis Institute Conclusions • Mild acid treatment of graphite results in local delamination • Au nucleation occurs at defect sites • Pretreatment with acid  HCl enhances Au nucleation & deposition  HNO3 generates larger gold nanoparticles • Au depositon in acid  HCl enhances nucleation of smaller particles  HNO3 generates larger particles Dennis Dowden Commemoration 3rd April 2013 27
  28. 28. Surface Science & catalysis Cardiff Catalysis Institute Next steps: Aqua Regia Fig. 3 Conversion () after 5 h and Au3+ () for Au/C catalysts containing different amounts of Au3+. The catalysts were obtained from impregnation using solutions containing different HNO3 volume fraction in the HCl/HNO3 mixture.“Modifications of the Metal and Support During the Deactivation and Regeneration of Au/C Catalystsfor the Hydrochlorination of Acetylene.”Marco Conte, Catherine J. Davies, Graham J. Hutchings et al.Catalysis Science & Technology 3, (2012) 128 Dennis Dowden Commemoration 3rd April 2013 28
  29. 29. Surface Science &catalysis Cardiff Catalysis Institute Funded by EP/I038748/1 Cardiff University CUROP awards Dennis Dowden Commemoration 3rd April 2013 29
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