Preparation Of Molybdenum Phosphide Catalysts For Deep Hydrodesulfurization

Petrochemical is the pillar industry of our country, during nowadays, petroleum resourse is still the main resource of the motor fuel and organic chemistry. To optimize and clean the crude oil, have very important strategic significance for the sustainable development of economy and society.For those new energy resources like solar energy, hydrogen, bioenergy, etc., because of their costs and technical reasons, there is a long way to go before achieving a comprehensive industrialization. Therefore, to further enhance the quality of oil is effective and feasible measure. According to the current international situation and hydrodesulfurization experiment experiences accumulation of our laboratory these years, a new type of hydrodesulfurization catalyst—transition metal phosphides catalyst were chosen for research.Because mesoporous MCM-41 has a high surface area and a uniform pore structure, MCM-41 supported molybdenum phosphides (MoP) with different weight loadings were prepared via an in-situ TPR reduction and a sulfidation-reduction procedure from molybdenum and tungsten phosphate precursors by incipient wetness impregnation and characterized by XRD, XRF and TPR. The HDS performance of the prepared MoP catalysts were evaluated in a fixed bed reactor using dibenzothiophene (DBT) in decalin as the feed. The catalysts prepared by sulfidation-reduction have higher HDS activity than that prepared by reduction. The effect is more evident when the reduction end temperature is lower. Catalysts prepared by the two activation ways have different selectivity. The hydrogenation activity is more superior via a sulfidation-reduction method.To discuss the reasons that the HDS activity increases by sulfidation-reduction though adding the MoO₃ and NiO to the precursor materials. And come to the conclusion that MoP and MoS₂ have no synergism effect.In addition, to improve the HDS activity by using (NH₂)₂CS to modified the MCM-41/MoP and citric acid to modified the bulk MoP respectively, Better HDS activity is found in the catalysts modified by (NH₂)₂CS and citric acid.