Study Of Process Of Reaction-transformation-separation For Liquefied Petroleum Gas Desulphurization

The sulfur compounds in light hydrocabon,especially in LPG of refinery,have a great impact on the long period operation of the device and the product performance,such as producing MTBE,isomerization-dehydrogenation of alkane to propylene and isobutylene.At present,the main methods of desulfurization of LPG are alkaline washing,enhanced alkali washing or multistage fixed bed reaction and adsorption,but there are some problems,such as lack enough of sulfurization,limited capacity of adsorption or discharge of alkaline residue,whice hinder a long period and efficient,stable operation.With the larger scale of refinery and the coming moment of implementing state five standard of clean gasoline,low cost and high added value utilization of LPG had received increasing attention.Especially domestic refineries are mostly in the age of tiny profit.Through the analysis of the advantages and disadvantages of the present situation of the large quantities of industrial LPG desulfurization equipments,we put forward a new technology of sulfur removal process for sulfur compounds in LPG.In the process,we use special catalyst to make COS hydrogenated to generate H₂S,then H₂S reacts with propylene,butene and isobutene to generate propylmercaptan or butyl mercaptan,then they reacts with propylene,butene and isobutene to generate thioether by hydrogen addition reaction with methanethiol,ethanethiol in LPG,the boiling point of thioether is higher than C₂-C₄ light hydrocabon,they can be removed by distillation,so we get C₂-C₄ components with nearly no sulfur.In the thesis,we designed and prepared NiMo/?-Al₂O₃ catalysts by the successive incipient wetness impregnation,and investigated the effect of Ni/Mo atomic ratio on catalytic conversion property of sulfide in LPG.The reaction paths of thiol and olefin and the synergistic effect of different metal atomic ratio on thioetherfication activity had been proposed by the ethanethiol model compound.The surface area and pore volume of?-Al₂O₃ support decreased after loaded active components,and the average pore size changed little.With the increase of Ni/Mo atom ratio,the surface area increased accordingly,the amount of L acid increased firstly,then reduced,the amount of B acid declined and disappeared finally.The active components of catalysts dispersed very well before and after reaction.The results of TPR showed that adding Ni could improve the amount of easily reducible octahedral coordination Mo⁶⁺,it helps the formation of?type‘Ni-Mo-S'active phase.The active performance of hydrotreating catalysts was evaluated in different operation conditions by coking LPG from Jingbo Petrochemical on a 10ml fixed-bed high pressure microreactor.The results showed that the conversion rate of sulfide was more than 90wt%under the conditions of 160-180?,1.5MPa,LHSV 2.0h^-1,H₂/hydrocanbon 20:1.Sulfide content in raw materials can be reduced from 1400?g/g to less than 100?g/g.