Comparable investigation of spillover and cobalt promoter effects in CoMoS/CoSx/SiO2 catalysts for selective hydrotreating of model FCC gasoline

Abstract

Cox-Co2Mo10/SiO2 and Co2Mo10/Cox/SiO2 catalysts with various Co/Mo ratios and active species compositions are prepared using H6[Co2Mo10O38H4] heteropolyacid, CoCO3 and citric acid. Catalysts are characterized using the following techniques: low-temperature N2 adsorption, temperature-programmed reduction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Catalytic activities of the synthesized catalysts are examined in hydrotreating of model fluid catalytic cracking (FCC) gasoline that contains 1000ppm of sulphur from thiophene and 36wt.% of n-hexene-1. As the Co/Mo ratio increases, hydrodesulphurization (HDS) and hydrogenation (HYD) activities of the prepared catalysts significantly builds up. The changes of catalytic properties and specifically of the HDS/HYDO selectivity factor of the synthesized CoMo catalysts arise from two effects: an alteration of the promotion degree of CoMoS active phase particles and a hydrogen spillover from CoSx species to active sites. The developed silica-supported CoMo catalysts may be a prospect for selective HDS and hydro-upgrading of FCC gasoline.