Study On Preparation And Catalytic Oxidation Desulfurization Performance Of Mesoporous Molecular Sieve Modified By Metals

In order to reduce the problem of environmental pollution from sulfur compounds in the fuel oil,people established strict standard of sulfur content in fuel oil.It is difficult to remove organic sulfur compounds in the fuel oil in the form of thiophene compounds and their derivatives in the hydrodesulfurization process which will increase the cost of production.Therefore developing a new kind of desulfurization method which can be used in both deep desulfurization and high efficiency is in great request.In this paper,transition metal catalysts were prepared which with Fe and V as active components modified HMS and MCM-41 mesoporous molecular sieves.Oxidative desulfurization performance of two catalysts was studied using DBT as a model compound and the catalysts were characterized by NH3-TPD,XRD,H2-TPR and SEM.Catalytic oxidation desulfurization activity was investigated by examining the preparation methods,loading capacity,pH value of solution and calcination temperature.The oxidation desulfurization reaction kinetics was studied and the optimum process conditions were determined by orthogonal experiment.Research shows that the oxidative desulfurization effect of Fe-V-HMS catalyst synthesised by one step show higher activity than impregnation method.The desulfurization effect gets best when the catalysts were prepared under the condition of the synthesis solution pH value is 10,calcination temperature is 550 degree,Si/(Fe+V)=14.8,n(V)/n(Fe)=1:2,and the desulfurization rate could reach 97.1%.The optimum reaction conditions is obtained by orthogonal experiment: reaction temperature 60?,reaction time 45 minutes,oxidant dosages 8mL/L(oil),catalyst dosages 8g/L(oil).Under optimum condition of the reaction,the rate of desulfurization can reach more than 99%,DBT was oxidized to DBT-sulfone(DBTO2),a species with higher polarity that could be subsequently adsorbed on the Fe-V-HMS and therefore,the nanocomposite does not only possess a catalytic role,but also adsorption simultaneously.And the oxidation reaction of model compounds(DBT)in the presence of Fe-V-HMS catalyst be assumed as a pseudo-first-order reaction,and the apparent activation energy and rate constants was 43.79kJ/mol and 1.33 x 105 repectively.The V-MCM-41 catalyst prepared hydrothermally exhibited high catalytic activity when the pH and loading amounts of synthetic surrounding of catalyst was 10.5and 10 V individually,the desulfurization efficiency of 98.7%.The comparison of the process conditions of single-factor experiments,V-MCM-41 catalyst presented good catalytic activity in the following conditions determined: reaction time 60 minutes,catalyst dosages 3g/L(oil),oxidant dosages 6m L/L(oil),reaction temperature 70?.And the oxidation reaction of model compounds(DBT)in the presence of V-MCM-41 catalyst be assumed as a pseudo-first-order reaction,and the apparent activation energy and rate constants was 52.48kJ/mol and 8.04×106min-1 repectively.