Performance Comparison of HZSM-5 and SAPO-34 Catalysts for Conversion of Methanol to Ligholefins

In this study, the effect of two zeolites with different topologies (SAPO-34 and H-ZSM-5) in conversion of methanol to olefins (MTO) was comparatively investigated. The catalysts were hydrothermally synthesized and characterized by XRD, FTIR, SEM, BET, and TPD techniques. The performance of catalysts were carried out in a fixed bed reactor, at atmospheric pressure, 400 °C, WHSV of 2 h-1 and molar fraction of methanol in the feed is 0.3, which diluted with nitrogen. Due to the distribution of MTO reaction products, SAPO-34, small pore weak acid sites, showed the highest selectivity for light olefins such as ethene and propene, and no aromatics were detected, whereas H-ZSM-5, medium pore strong acid sites, indicated relatively high selectivity for light olefins like propene and butene, and high amount of aromatics were found. The study showed that the products distribution depends mainly upon the framework topology of the catalyst and olefin selectivity is found to be better when the catalyst has smaller particle size and larger pore volume. The high olefin selectivity is found in SAPO-34 about 96%, also high coke formation due to small pores of SAPO is observed that lead to rapid deactivation after 10 hours.