Preparation, characterization and hydrodesulfurization performances of Co-Ni2P/SBA-15 catalysts

Abstract

A series of Co-Ni2P/SBA-15 catalysts with various Co contents, Ni2P contents and P/Ni molar ratios were prepared by impregnating nickel nitrate, diammonium hydrogen phosphate, and then cobalt nitrate into SBA-15 support followed by temperature-programmed reduction in a H2 flow. The catalyst structure was characterized by X-ray diffraction (XRD), high resolution-transmission electron microscopy (HR-TEM) and N2 adsorption-desorption techniques and their catalytic performance of the hydrodesulfurization (HDS) of dibenzothiophene (DBT) was evaluated. The effects of Co contents, Ni2P contents and P/Ni molar ratios on the catalyst structure and HDS of DBT over the Co-Ni2P/SBA-15 catalyst were investigated. The results indicated that the mesoporous structure was mainly maintained and the nickel phosphides were well dispersed in all of the characterized catalysts. The 4Co-25Ni2P/SBA-15 (P/Ni = 0.8) catalyst with the Co and Ni2P contents of 4 wt% and 25 wt%, respectively, and the P/Ni molar ratio of 0.8 showed the highest catalytic performance for HDS of DBT. Under the reaction conditions of 380°C and 3.0 MPa, the DBT conversion can reach 99.62%. The HDS of DBT proceeded mainly via the direct desulfurization (DDS) pathway with biphenyl (BP) as the dominant product on all of the catalysts and the BP selectivity was slightly enhanced after the introduction of Co promoters.