Enhanced Catalytic Dehydrogenation of Methylcyclohexane over Colloidal Pt-Decorated Functionalized Graphene Sheets as Fuel Additives

This study explores the reaction mechanisms of hydrocarbon loaded with colloidal Pt-decorated functionalized graphene sheets (Pt@FGS) using high-pressure liquid flow reactor experiment and the reactive force-field (ReaxFF) molecular dynamics (MD) simulation. Previous work [Sim et al. Combustion and Flame, 217, 212-221, 2020] on the supercritical fuel decomposition of methylcyclohexane (MCH) loaded only with FGS showed that there is a slight enhancement in fuel conversion rate due to the interactions between oxygen-containing functional groups onto the FGS surface and fuel molecules. In this study, we present a remarkable improvement in the fuel decomposition and hydrogen formation of MCH resulting from the enhanced catalytic dehydrogenation by the suspension of Pt@FGS at a very low loading concentration. From high-pressure and high-temperature experiments, it was found that the bicomposite structure of Pt@FGS at the loading concentration of 50 ppmw served to lower the reaction energy and energy barrier for dehydrogenation, which could result in the enhanced conversion rates and increased reactive product yields such as hydrogen and low-carbon number species. Subsequent molecular dynamics studies provide evidence that the Pt nanoparticles attached to the FGS significantly catalyze the dehydrogenation of methylcyclohexane into intermediate C₇H₁₃ radical. Interestingly, when the presence of Pt@FGS in the fuel even at the very low concentration, the hydrogen yield is increased.