Effect of calcination temperature of TiO₂-Al₂O₃ mixed oxides on hydrodesulphurization performance of Au-Pd catalysts

Abstract

A series of TiO₂-Al₂O₃ mixed oxides calcined at different temperatures was prepared by the sol-gel method. The influence of calcination temperature of TiO₂-Al₂O₃ on Au-Pd catalysts was investigated in the hydrodesulphurization of thiophene. The structural and surface properties of the samples were analyzed by nitrogen adsorption, X-ray diffraction, temperature-programmed desorption, temperature-programmed reduction and infrared spectroscopy techniques. The results showed that the prepared TiO₂-Al₂O₃ mixed oxides had mesoporous structure. The TiO₂-Al₂O₃ mixed oxide calcined at 773 K exhibited larger BET surface area, pore volume and more acid sites than the samples calcined among 873-1073 K. All the Au-Pd catalysts supported TiO₂-Al₂O₃calcined at different temperature had higher catalytic activity towards the hydrodesulphurization of thiophene, and the catalytic activity of Au-Pd/TiO₂-Al₂O₃(773 K) was better than that of other samples in hydrodesulphurization reaction. This was explained in terms of their structure: interaction between Au-Pd and TiO₂-Al₂O₃, dispersion, apparent activation energy, the number of Au_xPd_y alloy particles and acid sites.