Influence Of Dialkene On Gasoline Upgrading And Its Adsorptive Removal

At ambient temperature and liquid conditions, the unsaturated hydrocarbons contained inthe gasoline take place oxidation, decomposition, polymerization and condensation reactionand so on in the presence of oxygen,which generate gasoline gum. In various unsaturatedhydrocarbons, the most unstable substance are conjugated diolefins,cyclic diolefin(such ascycolopentadiene) and polyeyclic aromatic hydrocarbons with side chains.A small amount ofthese hydrocarbons in the gasoline can easily generate gum.Although the nature of olefins isnot stable,the oxidation of olefins is slower than diolefins. A small amount of diolefins caneven promote saturated hydrocarbons to forming gum.During the industrial process ofgasoline upgrading, the content of gum increases and the end point raises,which affect thequality of gasoline.However,the causes and reaction mechanism have not been reportedbefore.Therefore,in this paper, the effect of diolefins on the process of gasoline upgrading wasinvestigated,and molecular sieve was used to remove diolefins by selective adsorption.Cracking C₅ contains large amount of diolefins.In this paper, the effect of diolefins onthe process of gasoline upgrading was investigated by adding Cracking C₅ into FCCgasoline.The results show that: Under the influence of diolefins,on the one hand,the capacityof desulfurization,reducing olefins and isomerization drops and the capacity of aromatizationenhances,which changed the ratio of aromatics and isoparaffins.On the other hand,the stabilityof reaction reduces. Therefore, it is necessary to remove olefins in the FCC gasoline.Molecular sieves were used to remove diolefins by selective adsorption.The effect of theolefin content in raw materials,temperature,operating pressure and feed rate was investigated.The results show that:At 100℃, 1.0MPa, 25%volume content of hexene in raw material,feed rate 20mL/h and carrier gas flow rate 30 mL/h,the capacity of HZSM-5 for removingdiolefins by selective adsorption is best. At 100℃, 0.6MPa,the volume content of hexene inraw material 25%,the feed rate 20mL/h and the carrier gas flow rate 30 mL/h,the capacity ofFDO-1C for removing dioleflns by selective adsorption is best.Comparatively speaking, theperformance of HZSM-5 for removing diolefins by selective adsorption is beset.