Methanol acts as a strong deactivating agent on sulfonic acid resin catalysts in the presence of thiols. In homogeneous solutions, methanol can react with dimethylsulfide (DMS) and mercaptans via alkylation to form a trimethylsulfonium (TMS) cation. Limited evidence has been reported in the literature on TMS formation on sulfonic resin and the mechanism by which it deactivates the catalyst. In this work, several experimental approaches were used to investigate the methanol deactivation mechanism on sulfonic acid catalysts. This included total acidic determination, catalytic evaluation, chemical analysis, and characterization of the spent and fresh catalysts. The elucidation of the poisoning species was determined by inspection of organic extractants and acidic solutions used in the catalyst regeneration. Initial screening of the acid regenerating solution by GC-SCD and GC-MS showed the presence of dimethylsulfide and other sulfur species. Trimethylsulfonium ions, however, were not directly detected, which can be explained by their unstable nature. The results suggest that ionic sulfur species strongly interact with sulfonic acid groups, consistent with the idea of TMS formation, according to the reaction: In the presence of a P-SO3H catalyst CH3SH + 2CH3OH ↔ (CH3) 3S+ P-SO3 + H2O This work proposes the sulfur species formation reaction paths suggesting a novel understanding of the alcohol deactivation reaction mechanism on sulfonic acid catalysts.

Elucidation of methanol poisoning mechanism of sulfonic acid catalysts

256th National Meeting (2018)

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