Effect Of Pore Structure And Acidity Of Carrier On The Performance Of FCC Gasoline Thioetherification

Catalytic cracking（FCC）gasoline accounts for 70%-80%of China’s finished gasoline,and FCC gasoline has higher sulfur content and olefin content.More than 90%of the sulfide in gasoline comes from FCC gasoline.In order to produce clean fuel that meets environmental requirements,it is becoming more and more important to reduce the sulfur content in FCC gasoline.Mercaptan etherification technology has obvious advantages in promoting deep desulfurization of FCC gasoline selective hydrodesulfurization process and maintaining octane number.In this paper,the synthesis of the catalyst’s ordered mesoporous Al₂O₃ carrier,the effect of the carrier’s pore structure,acidity modulation and metal modification on the Pd/Al₂O₃ supported catalyst were studied,and high desulfurization activity,selectivity and good stability were successfully developed Thiol etherification catalyst.The main research results are as follows:（1）Adopt sol-gel method,use aluminum chloride as aluminum source,polyethylene glycol as template agent,use 1-2 propylene oxide as coagulant,water and ethanol mixed solution as solvent,aging time is 24 h,The aging temperature is 40℃,dry directly without washing to synthesize ordered mesoporous alumina.（2）Through characterization of carriers with different pore sizes and Pd/Al₂O₃ catalysts,it was found that the pore structure and dispersibility and acidity of Pd/Al₂O₃ catalysts prepared by Al₂O₃ carriers with a pore size of 6 nm were better,which was more conducive to FCC gasoline desulfurization.Isoprene and 1-hexene mainly undergo cracking,double bond hydrogenation and isomerization,alkylation and aromatization reactions on the Pd/A1203 agent,thereby generating high-octane gasoline components;and The conversion rate of isoprene and 1-hexene is high,which can reach 90%and 65%respectively,and the selectivity of olefin is good,which can reach more than 75%;at the same time;it has a high ability to remove mercaptan,The conversion rate of thiol can reach more than 95%（<10ppm）.（3）Pd/Al₂O₃ catalyst supported on Al₂O₃ prepared with palladium chloride as precursor has higher mercaptan etherification activity,but lower olefin selectivity.The olefin selectivity of Pd/Mg-Al₂O₃ catalyst modified by metal promoter mg is higher,which can reach over 95%;the conversion rate of isoprene and 1-hexene is higher,which can reach more than 98%and 87%,respectively;the conversion of mercaptan has higher Capacity,thiol conversion rate can reach more than 98%（<10ppm）.Through physical characterization of the catalyst,it is found that the presence of a certain amount of L acid and weak acid center will be more conducive to the progress of thiol etherification and olefin hydrogenation saturation reaction.（4）Although the Pd/Ag-Al₂O₃ catalyst modified by active metal Ag has improved the conversion efficiency of thiol and the experimental life of the catalyst has also been extended,the conversion rate of 1-hexene and isoprene and the choice of olefin Sex has dropped.