Study On The Formation Mechanism And Catalyst Of Secondary Mercaptan For FCC Gasoline Selective Hydrodesulfurization

For a long time,with the vigorous development of fossil energy,non-renewable energy sources such as coal and petroleum have dried up,people's demand for energy is still growing,and challenges to environmental issues are also intensifying.As the concept of green chemistry becomes popular,environmental pollution of fuel has become an urgent problem to be solved.Among the blending components of gasoline in China,FCC gasoline is the main source,and formation of secondary mercaptan of FCC gasoline is an important obstacle to the upgrading of gasoline products in China.In this work,firstly,the periodic model of Co Mo S phase is selected and established.The adsorption process of cyclohexene and hydrogen sulfide on various models is calculated by VASP.It was found that reducing the proportion of Mo S₂ phase in the catalyst active phase and increasing the proportion of Co Mo S phase can suppress the formation of secondary thiols.Using HSC Chemistry for thermodynamic theoretical calculations,it was found that the addition reaction of cyclohexene and hydrogen sulfide tends to proceed spontaneously below 237.63?.By changing the load of Co and Mo on the catalyst,the effect of Co Mo S on the selective hydrodesulfurization performance of Co Mo Ce/Al₂O₃ catalyst in Mo S₂ was studied,which was characterized by the desulfurization rate,olefin saturation rate and thiol concentration in the product.The effects of Mo and Co content on the catalytically active phase of the catalyst were studied.The contents of Mo and Co change the hydrogenation activity of the catalyst,affect hydrodesulfurization activity,selectivity and thiol formation significantly.In the activity evaluation,the olefin saturation rate,desulfurization rate and thiol formation,found that the composition of 3.5%Co+4%Mo Co Mo Ce/Al₂O₃ catalyst has a good overall performance.The 3.5%Co+4%Mo Co Mo Ce/Al₂O₃ catalyst with the best performance was further adjusted for reaction conditions and applied to actual gasoline processing.The total sulfur content of the resulting product was reduced from 132?g·g^-1to 8.8?g·g^-1.Less than 10?g·g^-1required by the national VI gasoline standard,and the sulfur content meets the standard.The thiol content of the product was 3.4?g·g^-1.Through the doctor's test,the octane number lost 1.6 units.