Effect of Ga substitution with Al in ZSM-5 zeolite in methanethiol-to-hydrocarbon conversion.

The catalytic properties of conventional H-[Al]-ZSM-5 and gallium-substituted H-[Ga]-ZSM-5 were evaluated in the conversion of methanethiol to ethylene (CH ₃ SH → 1/2C ₂ H ₄ + H ₂ S). Dimethyl sulfide (DMS), aromatics, and CH ₄ were formed as byproducts on the H-[Al]-ZSM-5 catalyst. The introduction of Ga into the ZSM-5 structure provided a high ethylene yield with relatively high selectivity for olefins. Based on the temperature-programmed desorption of NH ₃ and pyridine adsorption on zeolites, the strength of acid sites was decreased by introducing Ga into the ZSM-5 structure. Undesirable reactions seemed less likely to occur at weakly acidic sites. The suppression of the formation of dimethyl sulfide (CH ₃ SH → 1/2C ₂ H ₆ S + 1/2H ₂ S) and the sequential reaction of ethylene to produce aromatics provided a high yield of ethylene over H-[Ga]-ZSM-5.
Competing Interests: There are no conflicts to declare.
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