Strengthening spillover hydrogenation of quinoline compounds over platinum-encapsulated amorphized HA zeolite catalyst

Abstract

Hydrogen spillover has been widely used in heterogeneous catalysis, yet how to explore the potential of catalyst support to further promote catalytic function of hydrogen spillover has rarely been investigated. Herein, platinum encapsulated into amorphized HA zeolite (denoted as Pt@HA) with generated hydroxyl groups was used as model catalyst to study the role of HA zeolite support on the promotion of catalytic performance in hydrogenation of quinolines to tetrahydroquinolines. Benefiting from small pore size of amorphized HA zeolite to prevent direct interaction of quinoline with encapsulated platinum, Pt@HA showed good catalytic selectivity in this transformation through hydrogen spillover. This remarkable catalytic selectivity was resulted from the interaction of hydroxyl groups at surface of HA zeolite with pyridine moiety through the formation NH bond to facilitate adsorption to make much lower apparent activation energy of Pt@HA for hydrogenation of pyridine moiety than that of benzene moiety, thus exhibiting enhanced catalytic selectivity.