Conversion of methanol to hydrocarbons over zeolite catalyst

Abstract

The production of olefins from different alternative sources is a topic of research for the scientific scientist community. During the formation of aromatic compounds on alumina-silica based catalytic surface, these olefins are formed as intermediates. Current research is undergoing to control the production of these intermediate and increase the selectivity of desired olefins namely ethylene, propylene and butylene. In catalyst different properties like alumina content, its place of siting in the framework (which influences the Bronsted and Lewis acid sites) and pore size plays an important role on conversion and selectivity. Four different alumina-silica based catalysts were initially investigated for methanol conversion to olefins. Preliminary studies were concentrated on four catalysts namely ASC, ZSM-5, MCM-22 and Al/MCM-41 for understanding the effect of the various parameters e.g. alumina content and micro/meso porosity of these catalysts. Thermal cracking of methanol was performed between 450-550oC to understand the kinetics of the formation of olefinic compounds. Another important parameter namely the effect of dilution with different kind of solvents including water was performed to understand the impact on the formation of olefins. 100% conversion was obtained in presence of MCM-22, Al/MCM41 and ASC at all temperatures whereas ZSM-5 could only give 95% at 550oC. It was observed that catalysts giving 100% conversion were mostly producing CH4 whereas ZSM-5 was able to provide a good yield of olefins. For further studies, ZSM-5 was used for methanol conversion to olefins. In the case of solvent addition, water presence although found to enhance the stability of catalyst however presence of CO and CO2 was observed which decrease the hydrocarbon formation. The effect of the presence... newline