Preparation Of Deep Hydrodesulfurization Catalyst For FCC Feedstock

Under the current situation,the deterioration and heavyness of crude oil are becoming more and more serious.Most of our country's imported crude oil is sulfur-containing or high-sulfur oil.In order to make FCC continue to play its important role in the production of refined oil products that meet environmental regulations,hydrocracking of FCC raw materials is an effective way.As the core of this technology,catalyst preparation has been highly valued and has been widely studied.Its purpose is to design catalysts with reasonable pore size distribution,high activity and long life.The main research object of this thesis is FCC raw material pretreatment catalyst,and the conversion rate of the model compound?the desulfurization rate and denitrification rate in the actual oil are investigated respectively to prepare the catalysts that meet the requirements.In this thesis,the preparation of Al₂O₃-Zr O₂ composite carrier is carried out by co-precipitation method.The influence of calcination temperature,reaction temperature,aging time and the amount of pore-enlarging agent during the preparation of the carrier is investigated.The results show that when the calcination temperature is 550°C,the reaction temperature is 40°C,the aging time is 18 h,and the pore-enlarging agent content is 10%,the prepared Al₂O₃-Zr O₂ composite oxide carrier has relatively superior properties.The surface area is 248 m²·g^-1,the average pore diameter is 8.5 nm,and the pore volume is 0.57 m L·g^-1.After determining the optimum preparation conditions,the paper investigates the effect of the introduction of zirconium on the characterization properties of the support and the activity in the hydrogenation reaction.The results show that the addition of proper amount of Zr O₂ can increase the proportion of acid in the catalyst,enrich the acid type of the catalyst,and weaken the strong interaction between the metal component and the carrier.The DBT is used as the reaction raw material to evaluate the hydrodesulfurization activity of different catalysts.The reaction conditions,Zr O₂ content and the effect of nitride on DBT conversion are summarized by chromatographic analysis of the reaction products.Liaohe coking wax oil is used as FCC raw material,the desulfurization rate and denitrification rate are taked as indicators.The hydrodesulfurization and hydrodenitrogenation performance of N i Mo/Al₂O₃-Zr O₂ series catalysts are investigated under such conditions:the space velocity is 1h^-1;the reaction temperature is 360°C,370°C,380°C,390°C;the ratio of hydrogen to oil is1000;the reaction pressure is 8MPa.The results show that the introduction of Zr O₂ can improve the hydrodesulfurization and hydrodenitrogenation performance of the catalyst,and the hydrodesulfurization and hydrodenitrogenation performance increase first ly and then decrease with the increase of Zr O₂ content.Among them,when the content of Zr O₂ is14%,the desulfurization rate and denitrification rate of the catalyst are the highest.Compared with the N i Mo/Al₂O₃ catalyst,the desulfurization rate and denitrification rate are increased by 10%and 25% respectively.