Effect Of Bulk Structures Of Support On Interfacial Oxygen Vacancies And Catalytic Performance Of Oxides Supported Metallic Catalyst

Oxides supported metallic catalysts have important applications in many fields,such as chemical production,environmental protection,and bio-catalysis.To oxides supported metallic catalysts,strong metal-support interaction induced by oxygen vacancies near the interface between the metal and the oxides support(V_os)is a crucial factor to affect the catalytic performance.However,oxides always have a great diversity of crystal structures even if they possess the same chemical composition.The complexity of bulk structure of support can lead to different V_os,which will further affect the catalytic performance of supported catalysts.In this thesis,titanium oxides supported platinum nano-catalysts were chosen as model to study the effect of the support bulk structure upon the V_os on supported metallic catalysts and the further catalytic performances.Rutile-type Ti O₂,rutile-type non-stoichiometric Ti O_2-xand cubic-phase Ti O were prepared by a wet chemical synthesis method with calcined P25 and lithium triethylborohydride.This method can easily obtain titanium oxides supports with different bulk structures from the same origin by adjusting the amount of reducing agent.By adsorbing Pt nanocrystals,three titanium oxides supported platinum model catalysts were prepared,in which the only discrepancy is the different bulk structure of support.With the model catalysts mentioned above and selective hydrogenation of o-chloronitrobenzene?o-CNB?as model reaction,effect of support bulk structure upon V_osand catalytic performance of the supported catalysts were investigated.It was found that bulk electron transfer,affected by conductivity of the support,can trigger the change of V_os charge,which further change the electron-deficient state of the supported Pt nanocrystals to impact the selectivity.Due to the different bulk structure of titanium oxides supports,moreover,the amounts of V_os generated under hydrogen atmosphere were different on the three model catalysts.Since V_os can promote the hydrogenation by polarizing nitro groups in o-CNB,the bulk structure of titanium oxides support also affected the catalytic activity of the supported catalysts.Both charge and amount of V_oscan be adjusted by bulk structure of the support,and the catalytic property of supported catalyst is further tuned by the synergistic effect of them.This work provides an important inspiration for designing and developing supported metallic catalysts with excellent catalytic performance,where the bulk structure of support should be seriously considered.