EFFECT OF AN ALKYL SUBSTITUTE ON HYDROCONVERSION OF INDIVIDUAL AROMATIC HYDROCARBONS ON Co/HZSM-5/SO42-–ZrO2 COMPOSITE CATALYST

Abstract

A systematic study of the hydrogenation of individual aromatic hydrocarbons (benzene, toluene, xylene) and their mixtures was carried out at 1800C, H2/Ar=7, WHSV = 2h-1 and atmospheric pressure on a composite catalyst 0.4%Co/HZSM-5/SO42-(2.0%)–ZrO2. It has been established that the developed catalyst has a high hydrogenating ability with respect to aromatic hydrocarbons at low hydrogen pressures. Alkyl-substituted benzenes turned out to be more active. It was found that alkyl substituents increase the activity of hydrogenation of the benzene ring of an aromatic hydrocarbon. According to their conversion, benzene, toluene and xylene form the following sequence: benzene<toluene<xylene. It was found that the optimal temperature for the process of hydroconversion of aromatic hydrocarbons on a composite catalyst is 1800C. The influence of the concentration of the hydrogenating component of the catalyst – Co on the hydroconversion was also investigated. It was found that the optimal concentration of Co is 0.4wt %. It has been established that in a benzene:toluene:xylene mixture, the conversion of benzene in comparison with its separate hydroconversion increases by more than 10%. The hydroconversion of aromatic hydrocarbons is accompanied by the formation of high-octane naphthenic hydrocarbons - cyclohexane, methylcyclohexane and methylcyclopentane. The antibatic change in the yield of CH and MCP with the duration of the experiment shows that the hydrogenation of the aromatic ring is primary and the isomerization of C6H10 to MCP is secondary, i.e. MCP is the result of a sequential transformation. The absence of dimethylcyclohexane (DMCH) in the benzene:toluene:xylene mixture conversion products suggests that the benzene and xylene conversions additionally involve transalkylation