Studies of Hydrodesulfurization Properties over Pd/ZrO_2-Al_2O_3 Catalysts

A series of ZrO_2-Al_2O_3 mixed oxides and Pd/ZrO_2-Al_2O_3 catalysts with various zirconium contents were prepared by the impregnation method.Hydrodesulfurization(HDS) reaction of thiophene over Pd/ZrO_2-Al_2O_3 catalysts was carried out in a flow reactor.XRD,TPR,H_2-TPD,NH_3-TPD and nitrogen adsorption techniques were used to characterize the samples.The result showed that the effect of zirconium content on HDS properties was observed over Pd/ZrO_2-Al_2O_3 catalysts.Introducing suitable zirconium into Pd/Al_2O_3 resulted in relatively higher dispersed-metal,more acid amount,more H_2 adsorbed amount and weaker metal-support interaction,and also leaded to the increase of the adsorption sites of thiophene and active centres,the decrease of the apparent activation energy,all of above mentioned factors were favorable for the HDS of thiophene.The maximum HDS activity was observed for Pd/ZrO_2-Al_2O_3 catalysts with zirconium content of 9%.