Effect of Regeneration Process on Structure and HDS Activity of Industrial NiMo/ γ Al 2O 3 Catalyst

The catalysts for hydrotreating process are widely used in petroleum industry and more and more studies are focused on the reuse of spent catalysts because of the environmental regulation and the high catalyst consumption. NiMo/ γ Al 2O 3 is one of the most important catalysts for the hydrodesulfurization (HDS)/hydrodenitrogenation (HDN) in petroleum industry. In this study, the effect of regeneration conditions on the physico chemical properties and catalytic performance of the spent catalysts was investigated. The regenerated samples were characterized by low temperature nitrogen adsorption, XRD, SEM EDS, IR and TPR techniques. The catalytic activities of regenerated samples were evaluated by catalytic hydrodesulfurization of diesel oil. The results show that for the samples regenerated at a suitable temperature, there is only a little change in the textural structure, the aggregate of active phase in the oxidized samples may change the coordination states of some active elements, decrease the reduction temperature and improve the HDS activity of the regenerated samples. The existence of sulfate ions does not affect the HDS activity of the regenerated catalysts.