Additives Modification Process Research Of CoMo/γ-Al₂O₃ Hydrodesulfurization Catalyst

With the rapid development of the humans, oil demand, the crude oil is becoming poorer. Environmental protection laws and regulations of all countries is becoming more and more strict, so more attention has been paid to the production of cleaner petrochemical products. In order to achieve the goal of producing cleaner energy products, the research and development of more efficient hydrogenation catalyst is one of the important means.The preparation method of the catalysts and hydrogenation catalyst modified with additives were studied in this paper.We studied the preparation method of Co Mo/γ-Al2O3 catalysts, and mainly examined the impregnation sequence, atom ratio and load of molybdenum and cobalt in Co Mo/γ-Al2O3 catalysts how to effect the hydrogenation desulfurization activity in this paper. In the hydrogenation catalysts, we regarded Co and Mo as active component,phosphorus and citric acid as the additives, γ-Al2O3 as the carrier and thiophene hydrodesulfurization reaction as the research object. The research results showed that the best impregnation sequence of molybdenum and cobalt were molybdenum and cobalt total immersion, the best Co/(Co+Mo) was 0.4, the best load of molybdenum and cobalt was5wt% and 14.5wt%. At this time the desulfurization rate of the catalyst was 94.4%.We conducted the modification research of phosphorus and citric acid in Co Mo/γ-Al2O3 catalysts, then applied a variety of means such as BET, XRD and TPR to the catalysts’ characterized and evaluated the hydrodesulfurization reaction performance of the catalyst. The study of phosphorus mainly included adding method and the amount of additives; the study of citric acid mainly included whether for roasting, adding methodsand adding quantity. The results indicated that the HDS activity was the highest when catalysts prepared with molybdenum, cobalt and phosphorus total immersion; Co MoP/γ-Al2O3 catalysts has the highest activity of hydrogenation desulfurization when phosphorus load was 2wt%. At this time the desulfurization rate of the catalyst was95.2%.The Co MoP-CA/γ-Al2O3 catalysts not calcined and prepraed with citric acid had the the highest HDS activity; Co MoP-CA/γ-Al2O3 catalysts had highest HDS activity when citric acid, cobalt, molybdenum and phosphate were total immersion;Co MoP-CA/γ-Al2O3 catalysts had highest HDS activity when mole ratio of citric acid and cobalt was 1. At this time the desulfurization rate of the catalyst was 96.0%. Phosphorus and citric acid can change the interaction between active component and carrier, improve the active component of dispersion, and increse the number of molybdenum species those can be restored.Eventually, the catalyst activity was promoted.