Controllable Reconstruction of the Ni/MgAl2O4 Catalyst by In Situ Liquid-Phase Reduction Combined with an Adsorption-Impregnation Strategy to Enhance Reaction Performance for MCH Steam Reforming

Abstract

Hydrogen production via catalytic steam reforming of high-carbon hydrocarbons, with low cost, strong adaptability, and easy industrialization, is one of the core technologies for addressing the hydrogen supply bottleneck of fuel cells. However, traditional synthesis methods usually lead to an uncontrollable chemical state of active metals, resulting in poor catalytic activity, low hydrogen selectivity, and rapid deactivation of catalysts. Herein, in situ liquid-phase reduction combined with an adsorption-impregnation method under mild conditions was developed to achieve the controllable regulation of Ni nanoparticle size, dispersion, and valence ratio in Ni/MgAl2O4 catalysts. The results showed that the NMA-160-2 catalyst with Ni nanoparticles that were reduced at 160 °C for 2 h exhibited excellent activity and stability (800 °C, WHSV = 202.3 h–1), which possessed the highest H2 selectivity (71.8%) and maintained the full conversion of methylcyclohexane for 22 h, with the carbon generation rate of 1.6 mg·gCat–1·h–1. It was attributed to highly dispersed and small-sized Ni nanoparticles with a high proportion of Ni0 obtained under this reduction condition, which favored the adsorption and activation of methylcyclohexane and mitigated carbon deposition on the surface of active sites. This work provides a valuable addition to the controllable preparation of high-performance reforming catalysts and the development of fuel cells.