Effect Of Pore Structure And Acidity Of ? Molecular Sieve On Sulfur Transfer Reaction Performance Of FCC Gasoline

In recent years,with the increasing pressure of environmental protection,the green development model has been strongly promoted and respected by the whole world.The production and use of clean energy has received more and more attention.The goal of clean gasoline production at this stage is low sulfur,low olefins,high octane number.Although the etherification desulfurization process has been industrialized and the desulfurization effect is remarkable,there is still a problem in the removal of the thiophene sulfide.Since the?molecular sieve is easy to adjust in structure and acidity,and has a large specific surface area,it is expected to have good sulfur transfer reaction performance after modification.Therefore,this paper put forward a research idea to couple the thiol etherification and thiophene alkylation process,and simultaneously remove the thiol,small molecule thiophene compound and diene in FCC gasoline.and the different treatment methods for?zeolite molecular carriers.It was studied that the influence of different treatment methods on the pore structure and acid properties of?zeolite,and the catalytic performance of the sulfur transfer reaction of Mo-Ni/?catalyst.The pore size of?zeolite is mainly treated by acid-base treatment.The?zeolite is treated with different concentrations of NaOH solution,and its structure,properties,catalytic activity and stability are compared.The optimum concentration of NaOH is 0.2 mol/L.Under this condition,the relative crystallinity of?zeolite is 68.82%,the long-range order is better,the mesoporous specific surface area is increased to 225 m²·g^-1,and the pore volume is increased to 0.58 cm³·g^-1,the BJH curve of?zeolite showed obvious mesoporous peaks at 3.5⁴ nm and5¹0 nm.The sulfur transfer performance of the Mo-Ni/?catalyst prepared by the modified carrier was further investigated.Compared with the unmodified catalyst at P=2.5 MPa,T=100°C and LHSV=2 h^-1,The conversion rate of thiophene increased from 27.41%to48.94%,the conversion rate of n-butyl mercaptan increased from 94.31%to 99.00%,so the stability of sulfide reaction was greatly improved,and the conversion of isoprene was improved from 74.72%to 79.53%,while the conversion of 1-hexene and cyclohexene did not change much.Then the alkali-treated?zeolite was modified by 0.1 mol/L citric acid,and its structure and properties were further improved.And the crystal structure of H??0.2M-NaOH+0.1M-NMS?zeolite was restored,the relative crystallinity was 70.49%.and the relative crystallinity was improved.The mesoporous specific surface area and pore volume were further increased to 247 m²·g^-11 and 0.71 cm³·g^-1,and the mesoporous peaks moved toward the large pore direction.For sulfur transfer reaction performance,the Mo-Ni/?catalyst prepared by investigation was investigated,thiophene conversion rate was 60.23%,n-butyl mercaptan conversion rate was 99.02%,sulfide conversion stability was improved,isoprene conversion rate was 85.79%,1-hexene and cyclohexene's conversion rate had increased slightly.The acidic modulation of the?zeolite was mainly achieved by the acidic auxiliary F,and it was found that the 0.5wt%F modified?zeolite exhibited the best reactivity and stability.The addition of 0.5wt%F can enhance the medium strong acid content of H?zeolite,while the total acid amount increased from 752.84?mol·g^-11 to 975.49?mol·g^-1,L/B ratio changed from0.19 to 2.28,and the acid distribution was optimized.On the prepared Mo-Ni/F-?catalyst,the conversion of thiophene was 66.73%,the conversion of n-butyl mercaptan was 99.80%,the conversion of isoprene was 89.62%,and the conversion of 1-hexene was less than 9%.The conversion of cyclohexene did not exceed 16%,and the catalytic performance was greatly improved.