Effects of sulfur on dehydrogenation of methylcyclohexane over platinum catalysts

Journal article, 2026

Liquid organic hydrogen carriers (LOHCs) enable storage and transport of H2 using existing liquid fuel infrastructure, through reversible catalytic hydrogenation and dehydrogenation of organic molecules. A viable, commercially deployed LOHC system is the methylcyclohexane (C7H14)/toluene (C7H8) system. However, Pt-based catalysts, which are used for both hydrogenation of C7H8 and dehydrogenation of C7H14, also promote unwanted C–C bond scission, leading to demethylation and LOHC degradation. One route to prevent C–C bond scission over Pt catalysts is to mildly poison the catalyst with sulfur. Using density functional theory (DFT) calculations and mean-field microkinetic modeling, we show that the presence of sulfur, besides suppressing demethylation, also improves the C7H14 dehydrogenation activity. The enhanced performance is a result of sulfur destabilizing neighboring co-adsorbates, which promotes C7H8 desorption. The computational results for dehydrogenation over Pt surfaces reproduce experimental trends for alumina-supported Pt nanoparticles, suggesting that controlled, moderate sulfur poisoning is a universal means to improve the overall performance of Pt catalysts for LOHC dehydrogenation.