Study On Desulphurization From FCC Gasoline And Diesel Oil By Catalytic Oxidation-Extraction

With the development of science and technology, people pay more and more attention to the environment protection. The waste gas from automobile has been drawn wide attention. The content reduction of sulfur in the oil is becoming stricter and stricter. In our country, fluidized catalytic cracking (FCC) gasoline and diesel oil account for 80% of gross production. So desulphurization of FCC gasoline and diesel oil becomes a global necessity. At present, hydrodesulphurization and nonhydrodesulphurization desulphurization techniques are used. Both of techniques have their advantages and disadvantages. According to the characteristics of sulfur compounds in FCC gasoline and diesel oil, the catalytic oxidation-extraction and solvent extraction method is used to diesel oil and gasoline for desulphurization respectively.The advantages of the catalytic oxidation-extraction method are that can be operated on quite temperate conditions, run at low cost and simple equipment. Hydrogen peroxide solution is used as the oxidant, cobaltous and mangenese stearate are used as the catalyst, acetic acid is used as solvent to oxidize organic sulfur in FCC diesel and turn it to corresponding sulphone, then extract sulphone to complete desulphurize operate. The effect of operation condition such as the ratio of n(CH₃COOH)/n(H₂O₂), n(cat)/n(H₂O₂), n(H₂O₂)/n(Ts) , reaction temperature and reaction time on desulphurization efficiency was studied. The researching results indicated that the system hydrogen peroxide-acetic acid-cobaltous stearate can transfer organic sculptures to sulphone efficiently.The major characteristic of the solvent extraction method is its' economic practicality. The solvent can be repeatedly used after regeneration. To FCC gasoline, four different alcohols are applied to the extraction desulphurization. Sulfolane and diethylene glycol may realize the solvent regeneration easily by the atmospheric distillation regeneration, and it still has the good extract effect.The experimental results indicated that through catalytic oxidation-extraction method the sulfur content of FCC diesel oil can dropped to 243ug/g from 2239ug/g with a desulphurization rate of 89% at n(H₂O₂)/n(Ts)=6, n(Co(C₁₇H₃₅COO)₂)/n(H₂O₂)=1/20, n (CH₃HCOOH) /n (H₂O₂) =20, reaction temperature 80℃, reaction time 90min. Through solvent extraction method the sulfur content of FCC gasoline can dropped to 297ug/g from 1509ug/g with a desulphurization rate of 80.3% at room temperature, solvent/gasoline=1, four times extraction cycle.