Homologation: The pathway of olefine conversion over pentasil zeolites

Abstract

Catalytic conversion of low concentration of gaseous mixtures of various alkenes in He over NiS modified zeolite of pentasil type was studied. Based on the established changes in the distribution of the products of catalytic conversion of alkene with a change in the reaction temperature and the concentration of alkene, benzene and CH3l in gas mixture, the model of the mechanism of catalytic conversion of alkene on zeolite catalyst was proposed. According to the model, the catalytic conversion, depending on reaction conditions, develops in three stages. In the first stage the transformation alkene fragments (cracks) and forms the so-called C1-intermediate particles. The formed C1-intermediate particles interact with the alkenes present in the reacton system by homologation reactions (the second stage of the transformation) which results in the growth of the carbon chain of the initial alkene. At high concentrations of the initial alkene, newly formed alkenes of relatively high molecular mass undergo disproportionation (the third stage of the transformation). The presumed model completely explains the changes appearing in the distribution of the products of catalytic conversion of alkene on the studies zeolite, under the influence of the changes in the reaction temperature and the concentration of alkene CH3l, and benzene in the gaseous mixture.