Study On The Process Of Sulfolane Selective Hydrodeoxygenation

Tetrahydrothiophene（THT）is an important sulfur-saturated heterocyclic compound,mainly as gas odorant.Compared with the traditional trahydrothiophene synthesis process,thiophene catalytic hydrogenation,tetrahydrofuran direct thio method and1,4-dichlorobutane thio method,the new technical route of sulfolane selective hydrodeoxygenation to synthesize tetrahydrothiophene has many advantages,such as chemical cheap,the process safe and with no environmental pollution and with high product yield etc.In this study,using the Ni-Mo metal oxide prepared by the sol-gel method as the catalyst and the ethylbenzene as the solvent,the stability of the catalyst for selective hydrodesulfurization of sulfolane was examined in the continuous fixed bed,and the catalysts were comprehensively characterized by XRD,EDS,BET,DSC-TGA,ICP-AES,and SEM,and the deactivation mechanism of the catalyst was investigated.Then,the global kinetic equation of the selective hydrodeoxygenation of sulfolane was established,and based on the two-dimensional pseudo-homogeneous model of industrial scale reactor,the influence of process variables on the reaction was simulated.The results of DSC-TGA,N₂-BET,ICP-AES and SEM characterization showed that the deactivated catalyst did not lose the active components and was sinteried.Although the carbon deposition resulted in the decreasing obviously of specific surface area,pore size and pore volume of the catalyst,the effects of these changes had little influnce on the catalyst performance.The Mo and Ni active components in the catalyst were sulfided to form MoS₂ and Ni₃S₂ phases by the side product H₂S,with the increase of the reaction time,the sulfur content on the catalyst increased gradually,which finally leaded to the formation of Ni-Mo-S active phase with strong hydrodesulfurization activity.This was the main reason for the decrease of the catalyst selectivity.In addition,the catalytic performance of the deactivated catalyst can be effectively recovered by burning sulfur and coke.The thermodynamic simulation of the selective hydrodeoxygenation process of sulfolane showed that the process is an exothermic and irreversible process.Based on the data of sulfolane hydrodeoxygenation reaction over the Ni-Mo catalyst,the power function kinetic model of the selective hydrodeoxygenation of sulfolane was developed,and the residual analysis and statistical test results of the model indicated that the global kinetic model was reliable.The two-dimensional pseudo-homogeneous model of the industrial-scale shell-and-tube fixed bed reactor for sulfolane selective hydrodeoxygenation was developed,and the effects of operating conditions,such as liquid hourly space velocity,reactor inlet temperature,operating pressure,sulfolane concentration,hydrogen/oil ratio and cooling medium temperature on the reactor temperature distribution,sulfolane conversion and selectivity of tetrahydrothiophene were simulated.The results showed that the temperature difference and the concentration difference in the radial direction of the bed were not dramatically,and the syitable operating conditions were as follows,liquid hourly space velocity 1h^-1,inlet temperature 503.15K,operating pressure 0.3-0.4MPa,mass concentration of sulfolane in the feed 10%,volumn ratio of hydrogen to oil 200,boiling water temperature outside 493.15⁵03.15K.