Study On Desulfurization Process Of Modified TiO₂/ZSM-5 Photocatalytic Oxidation Diesel Oil

The burning of sulfur in oil to SOx can cause serious environmental problems.Hydrodesulfurization is the most common method for oil desulfurization,but it has high operating cost and demanding conditions.Photocatalytic oxidation desulfurization is an advanced oxidation technology.Due to its advantages of low cost,mild conditions,no sundry introduction,high efficiency and catalyst reuse,it has gradually become the focus of research at home and abroad in recent years.In this study,TiO₂/ZSM-5 catalyst was prepared by impregnation method with titanium as the active component and ZSM-5 as the carrier of the catalyst.On this basis,two auxiliary metals nickel?Ni?and tungsten?W?were introduced to further improve the photocatalytic activity of TiO₂.The desulfurization performance of NiO-TiO₂/ZSM-5 catalyst and WO₃-TiO₂/ZSM-5 catalyst were studied respectively,and their structures were characterized and analyzed.Moreover,the photocatalytic oxidation desulfurization system was formed by combining the catalyst and H₂O₂.?1?NiO-TiO₂/ZSM-5 catalyst was synthesized by supersaturated impregnation method.The samples were characterized by a series of methods.The characterization results show that nickel are only highly dispersed on ZSM-5 surface;The introduction of nickel can accelerate the electron migration rate,effectively reduce the composite probability of photo-generated electron holes,widen the response range of light and improve the photocatalytic activity.The effects of a series of reaction conditions of photocatalyst on desulfurization performance were investigated.The results showed that the calcination temperature 550?,roasting time 4 h,TiO₂ and NiO load of 15%?w?and 1.2%?w?catalyst desulfurization effect best?The desulfurization rate of simulated diesel oil can reach is 92.86%when the catalyst dosage is 2g/L,n?H₂O₂?/n?S?is 4,reaction temperature is at70?and the reaction time for 3 hours.The desulfurization rate of real diesel oil is 65.46%.Furthermore,the photocatalytic oxidation kinetics of dibenzothiophene was investigated.The photocatalytic oxidation of it can be treated as a first-order reaction,E_a is 24.94 kJ/mol and the pre-exponential factor A is 1.08×10⁵min^-1.?2?WO₃-TiO₂/ZSM-5 photocatalyst was prepared by supersaturated impregnation method using butyl titanate and ammonium metatungstate as raw materials and was used in the simulation of photocatalytic oildesulfurization.The catalysts were characterized by a series of methods and the optimal reaction conditions of the desulfurization experiments of WO₃-TiO₂/ZSM-5 catalysts were investigated and the desulfurization experiments of the simulated oils prepared by different organic chlorides were studied.The characterization results show that the structure of the ZSM-5molecular sieve is retained.the introduction of tungsten can shift its optical response towards visible region,enhance its photocatalytic activity and its absorption of sunlight.The experimental results show that when the optimum loading of WO₃ and TiO₂ are 2.5%?w?and 20%?w?,the reaction temperature of desulfurization experiment is 60°C,and the light time is 4h.When the ratio of catalyst and oil is 1:40,the desulfurization rate of WO₃-TiO₂/ZSM-5 photocatalyst is the highest,reaching 98.7%;WO₃-TiO₂/ZSM-5 catalyst has different removal effects on different kinds of organic chlorides,and the removal rate of DBT is the best.The catalyst still has good desulfurization effect after repetitive use for five times.GC-FPD analysis of real diesel shows that many sulfides such as benzothiophenes and dibenzothiophenes are mainly removed.