Intrinsic kinetics of benzyltoluene hydrogenation over a supported Ni catalyst for green hydrogen storage

Abstract

Liquid organic hydrogen carrier technology is a promising alternative for hydrogen storage and transportation. Benzyltoluene (BT) is a high-performance hydrogen storage carrier, but the hydrogenation kinetic parameters that are important to guide reactor and catalyst design are not clear. Here, we systematically investigated the kinetics of BT hydrogenation over a supported Ni catalyst for its potential application in hydrogen storage. Our results suggest that BT hydrogenation reaction follows a two-step series reaction from BT to 12H-BT with 6H-BT as the intermediate. The reaction order is 0 and 1 with respect to BT and 6H-BT concentration, respectively, whereas that with respect to H2 pressure is approximately equal (1.0 and 1.1 for BT and 6H-BT hydrogenation, respectively). Calculated activation energy suggests that 6H-BT hydrogenation is the rate-determining step in the whole process. Moreover, both kinetic and DFT results indicate that the presence of BT would inhibit the further 6H-BT hydrogenation to 12H-BT. This study is expected to provide a new understanding of BT hydrogenation reactions and a useful guideline for reactor and catalyst design.