Influence of sulfur contamination on ethylene aromatization over a Ga-modified MFI-type zeolite

Abstract

To develop a new CO2 utilization process from sulfur-containing gases, such as sour gas and biogas, we investigated the influence of trace amounts of sulfur gas, namely hydrogen sulfide and methanethiol (CH3SH), on ethylene aromatization over an MFI-type zeolite catalyst. The protonated MFI-type zeolite showed high activity and stability for ethylene aromatization; however, its activity rapidly deteriorated in the presence of trace amounts of CH3SH. To improve the catalytic activity, zeolite was modified with Ni, Cu, Zn, and Ga. Although modifications with Ni, Cu and Zn did not improve the catalytic activity for ethylene aromatization, Ga modification contributed to the stability of ethylene aromatization in the presence of trace amounts of CH3SH. Characterization of the as-made catalysts indicated that Ga modification not only weakened the surface acidity of the zeolite but also endowed the catalyst with dehydrogenation capability. These properties suppressed CH3SH decomposition on the acid site, leading to stable catalytic performance for ethylene aromatization in the presence of trace amounts of sulfur gas.