Selective Hydrogenolysis of Methylcyclopentane in the Presence of Excess Methylcyclohexane Using Ir/SiO2 Catalyst

Methylcyclohexane (MCH) is a promising candidate for use as a liquid organic hydrogen carrier, but is isomerized into undesirable five-membered-ring compounds with similar boiling points to MCH, so purification requires selective conversion of the five-membered-ring compounds without reaction of the MCH. We found that an Ir/SiO2 catalyst efficiently promoted the selective hydrogenolysis of methylcyclopentane (MCP), a model five-membered-ring compound, in the presence of excess MCH in the reaction system. Ir/SiO2 and Rh/SiO2 catalysts provided high conversions in the hydrogenolysis of MCP at 200 °C, whereas almost no reaction of MCH occurred. In contrast, Pt/SiO2 catalyst was almost inactive in the hydrogenolysis of both MCP and MCH at 200 °C. The difference in reactivities for the Ir/SiO2 and Rh/SiO2 catalysts can be explained by the relatively high strain energy and formation enthalpy of MCP compared to MCH. The Ir/SiO2 catalyst also preferentially promoted the hydrogenolysis of ethylcyclopentane, which is a more realistic impurity, in the presence of excess MCH.