Intrinsic Kinetics of Fixed-Bed Hydrogenation of Benzyltoluene over Commercial Ni Catalysts

Abstract

Liquid organic hydrogen carriers (LOHCs), particularly benzyltoluene (BT), offer a promising solution for scalable hydrogen storage, yet their industrial deployment is hindered by a lack of reliable kinetic data for continuous fixed-bed reactors. This study reports the first intrinsic kinetics of BT hydrogenation over a commercial Ni/γ-Al2O3 catalyst in a fixed-bed reactor. By systematically eliminating external and internal diffusion effects, a robust power-law model is established for industrially relevant operating windows. The reaction follows a consecutive pathway. The first hydrogenation step of BT exhibits zero-order dependence on BT concentration and 0.71 order on hydrogen pressure, while the second step shows 0.71 order on the intermediate H6-BT and 1.28 order on hydrogen pressure. Activation energies of both hydrogenation steps are 45.80 and 112.80 kJ·mol–1, respectively, revealing the second step as rate-determining. The model achieves excellent predictive accuracy (average relative error of 8.80%), providing a computationally efficient foundation for rational reactor design and scale-up.