1-Methylnaphthalene Hydrogenation over Supported Precious Metal Catalysts: A Kinetic Study for Deciphering the Roles of the Metal and Support

The hydrogenation of 1-methylnaphthalene, commonly found in several carbochemical and petrochemical streams, is studied with the aim of using it as a liquid organic hydrogen carrier (LOHC). Due to the novelty of the proposed use, noble metal catalysts (Pd, Pt, Rh, and Ru) supported by activated carbon or alumina were selected. The reactant initially hydrogenates into both 1-methyltetralin and 5-methyltetralin and further into four stereoisomers of 1-methyldecalin. The proposed mechanism involves not only hydrogenation steps but also isomerization reactions between the intermediate and final products. The Rh/Al2O3 catalyst exhibits faster kinetics, highest selectivity to methyldecalins, and larger stability. By contrast, deactivation on the rest of the catalysts supported on alumina is important. Catalyst deactivation seems to be related to the formation of 1MN.