Study of the properties of pentasil-containing catalysts in reactions of transformation of hydrocarbons 5. Kinetics and mechanism of aromatization of propane and propylene on Ga and H forms of pentasils

Abstract

The kinetics of transformations of propane and propylene on Ga-modified pentasils and the H-form of zeolite were investigated in a wide range of conversions (20–95%). The selectivity of formation of aromatic hydrocarbons (ArH) on Ga-pentasils is significantly higher than on HTsVM. Quantitative data which demonstrate acceleration of aromatization of propane and propylene in modification of H-TsVM zeolite with gallium were obtained. An especially large increase in the reaction rate is observed in the case of the starting olefin: the rate constants on Ga/HTsVM and HTsVM are respectively equal to 9.21 and 1.44 sec−1. The significant effect of H2 on the selectivity of action of the Zn/HTsVM system in aromatization of propane was demonstrated. The effect of H2 was virtually not manifested on Ga/HTsVM in the conditions studied. The data obtained in the study permitted introducing important corrections in the scheme of the mechanism of aromatization of lower alkanes examined in the literature.