Effect of TiO2 oxygen vacancy content on catalytic performance of AuPd/TiO2 for benzyl alcohol oxidation
Three different AuPd/TiO2 catalysts were prepared via sol-immobilization method by loading active components Au and Pd onto the TiO2 supports(TiO2-G,TiO2-E and TiO2-H),which were synthesized by using tetrabutyl titanate as raw material through hydrothermal method,and characterized by XRD,XPS,N2 adsorption-desorption isotherm,EPR,ICP-AES,TEM and HRTEM.The effect of different oxygen vacancy content in TiO2 on the catalytic performance of AuPd/TiO2 for solvent-free oxidation of benzyl alcohol was analyzed.The results showed that AuPd/TiO2-G,with the highest oxygen vacancy content(0.198)and the smallest sized AuPd nanoparticles(1.83 nm),exhibited a transformation frequency of 70554 h-1,significantly better than AuPd/TiO2-H(39512 h-1)and AuPd/TiO2-E(14814 h-1),and the lowest apparent activation energy(55.77 kJ/mol),obviously lower than AuPd/TiO2-H(72.78 kJ/mol)and AuPd/TiO2-E(82.83 kJ/mol),indicating the best benzyl alcohol catalytic oxidation performance at 120℃.A higher content of oxygen vacancy in the support was conducive to the formation of smaller-sized AuPd nanoparticles and a higher content of surface Pd0 species on the catalyst surface,which was the key in achieving the excellent catalytic activity of AuPd/TiO2-G in the benzyl alcohol catalytic oxidation reaction.
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