Effect Of Induced Migration On Performance And Mechanism Of NiMo/Al₂O₃-HY Catalyst Hydrodesulfurization

With the increasing trend of crude oil quality and deterioration worldwide,it is particularly important to use high-activity hydrodesulfurization catalysts for the production of clean fuel oil.Alkyl-substituted polyaromatic ring sulfur compounds in crude oil account for about 30%to 70%,which 4,6-dimethyldibenzothiophene(4,6-DMDBT)has high steric resistance on both sides of the sulfur atom and the most difficult to remove.The addition of zeolite to the catalyst carrier can reduce the internal resistance of 4,6-DMDBT through Bronsted acid isomerization,and significantly improve hydrodesulfurization activity.However,the strong acid center will also cause cracking reaction of the product and reduce the liquid yield.In this paper,the synergistic effect of the B acid center on the zeolite and the catalyst metal is used to realize the induced migration of the acid center to the metal,which reduces the strong acid center and improves the distribution of the metal on the catalyst surface.The thesis researched by changing the p H value of the metal impregnation solution and changing the ratio of molecular sieve in the carrier to adjust the induced migration of the metal to the acidic components of the carrier,and the prepared Ni Mo/Al₂O₃-x HY catalyst was evaluation of the hydrodesulfurization reaction of 4,6-DMDBT,and analysis of the hydrodesulfurization activity and reaction path activity of different catalysts from a kinetic point of view.At the same time,in order to explore the effect of the induced migration mechanism in the presence of nitrogen-containing compounds on the reaction,the quinoline poisoning reaction of the above catalyst was also evaluated and the kinetic model of 4,6-DMDBT hydrodesulfurization under quinoline poisoning was established.In order to explore the mechanism of the effect of induced migration on the hydrodesulfurization performance of Ni Mo/Al₂O₃-HY catalysts,the paper also performed XRD,H₂-TPR,Raman,TEM,XPS characterizations on different Ni Mo/Al₂O₃-x HY catalysts.The results show that the alkaline metal immersion solution is beneficial to induce the migration process,and the effect of inducing migration is the most significant when p H=9.The introduction of HY zeolite into the carrier to form B acid centers can promote the occurrence of metal-induced migration,but as the content of HY increases,the induced migration of metals by B acid centers is restricted.The metal impregnation solution p H=9,the catalyst prepared with the HY content of 5%has the most obvious effect of inducing migration.The active metal on the catalyst is easily sulfided,forming high-stacked and long Mo S₂ platelets with high reaction activity.In addition,there are fewer cracking reactions and high catalytic activity after quinoline poisoning.