Study On Oxidative Desulfurization Of FCC Gasoline Over Super Solid Acid Catalyst

Gasoline fuel sulfur level has been identified as a major contributor to air pollution. In order to decrease pollution,new specifications for sulfur in gasoline have been established in many countries.In our country,FCC gasoline accounts for 70-80% of gross production. So it has been a great significance for the FCC gasoline desulfurization research. Nevertheless,the traditional hydrodesulfurization(HDS) process becomes insufficient with the drastically lower sulfur in liquid fuels. Therefore,a number of alternative technologies are being explord to realize the ultra-deep desulfurization to meet the future legislation on sulfur content. Nowadays,oxidative desulfurization was considered as one of the promising processes for its mild reaction condition,simple equipment design,and highly efficiency.In this paper,the oxidation-extraction desulfurization of FCC gasoline process via a novel solid acid catalyst is studied for the motive to produce Ultra-deep desulfurization of liquid fuels. Solid acid catalysts were preparaed by impregnation method,such as SO₄^2-/Fe₂O₃,SO₄^2-/ZrO₂ and SO₄^2-/ZrO₂-SiO₂ which were the highly effective,highly selective oxidation and low price.The oxidation of FCC gasoline was conducted under mild conditions,then it was extracted by polar solvent.Meanwhile,the effects of the catalyst style,the reaction temperature,the reaction time,the amount of hydrogen peroxide,the catalyst dosages were discussed.The result of experiments showed that the reaction temperature has complex impact on the sulfur removal,for example,the yield of FCC gasoline will become lower when the temperature is over high.Hydrogen peroxide has been selective oxidative desulfurization on FCC gasoline,and appropriate amount of hydrogen peroxide could accelerate the reaction rate.While over-dose hydrogen peroxide oxidate those unsaturated hydrocarbons. Furthermore,extraction conditions such as extraction concentration,solvent/oil,are investigated in the desulfurization of FCC gasoline.During the study on the semi-coke loaded SO₄^2-/Fe₂O₃,the results of experiment indicate that the optimum reaction conditions wer as follows: a catalyst dosage of 3wt.%,reaction temperature at 60℃,reaction time at 1.5h,the volume ratio of the hydrogen peroxide to FCC gasoline at 2:15,extracted with DMF (solvent/oil=1:1,by volume)at ambient temperature.Under this optimum condition,the removal rate of FCC gasoline reached 69.5%.During the study on the SO₄^2-/ZrO₂, the sulfur removal efficiency of FCC gasoline reached 50.8%,when the operating conditions were as follows: a catalyst dosage of 3wt.%,reaction temperature at 60℃,reaction time stirring for 1h at 1000rpm,the volume ratio of the hydrogen peroxide to FCC gasoline at 1:10,extracted with DMF (solvent /oil =1:1,by volume) at ambient temperature.This paper pays more attention to SO₄^2-/ZrO₂-SiO₂. The result from orthogonal experiments show that the order of the four factors for the sulfur removal efficiency is:the reaction temperature>the mass percent content of catalyst>the volume ratio of the hydrogen peroxide to FCC gasoline> the reaction time.the operating reaction conditions were as follows: 0.3wt.% of catalyst, reaction temperature at 35℃,reaction time stirring for 1h at 1000rpm,the volume ratio of the hydrogen peroxide to FCC gasoline at 1:10,extracted with Acetonitrice(solvent/oil =1:1,by volume).Under this optimum condition,the removal rate of FCC gasoline reached 69.5%.After oxidated and extracted,the gasoline was analyzed by GC-FPD,it was found that all most of the BT and MBT are removed,which indicates that the oxidation-extraction desulfurization can efficiently removes these recalcitrant sulfur species that hydrodesulfurization(HDS) process is less effective.