Light olefin production from methanol using various zeolite catalysts has industrial and economic importance considering the growth of the petrochemical market. Zeolites are generally synthesized using various organic templates as structuredirecting agents (SDAs). In this study, synthesis of a series of ZSM-5 zeolites was performed systematically using the microwaveassisted crystallization method, and these samples were analyzed in detail to understand the effect of the SDA concentration. Powder diffraction, N2 adsorption, scanning electron microscopy, ammonia adsorption desorption, and 27Al and 29Si NMR spectroscopies were used for the characterization. The organic SDA tetrapropyl ammonium hydroxide (TPAOH/SiO2 mole ratio = 0.0500) is found to have an optimum concentration against the silica precursor for achieving the highest crystallinity, suitable morphology, ideal pore size, effective pore volume, and tuned microporous/mesoporous area. For samples with a template concentration ratio of 0.050 or higher, 29Si and 27Al NMR data revealed the presence of an intact ZSM-5 structure. Using a fixed bed reactor at 500 °C and atmospheric pressure, the catalytic performance of the selected catalysts from the series is investigated for the methanol-to-olefin conversion reaction. The sample with the highest crystallinity showed the best conversion, selectivity toward light olefins, and time on stream stability. It is also worth noting that the highest crystallinity, micropore area, and micropore volume are reached for the optimum value rather than the highest template concentration. This allows for a reduction in the template concentration and a move closer to a synthesis pathway benign to environment and economics.
Bibliographical noteFunding Information:
The authors greatly acknowledge the research funding from the Deanship of Research Oversight and Coordination (DROC), King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia. The authors would like to acknowledge the Interdisciplinary Research Center for Hydrogen and Energy Storage (IRC-HES), and the Interdisciplinary Research Center for Refining Advanced Chemicals (IRC-RAC), King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia for hosting and supporting the research activities.
© 2022 American Chemical Society.
ASJC Scopus subject areas
- Chemistry (all)
- Chemical Engineering (all)