Acid-Modulated Ni/MCM-41 Catalysts Enhance Metal-Support Interaction for Efficient Perhydro-N-Ethylcarbazole-Based Hydrogen Storage and Effective Impurity Gas Suppression

Abstract

The rational design of cost-effective catalysts with tailored metal-support interactions (MSI) is pivotal for advancing liquid organic hydrogen carrier (LOHC) technologies. Herein, report a novel acid-modulation strategy to engineer Ni/MCM-41 catalysts by tuning Si/Al ratios, which enhances MSI through the creation of Si-OH-Al Brønsted acid sites. Systematic characterizations like NH₃-TPD, in situ Py-FTIR and HRTEM combined with DFT calculations reveals that reduced Si/Al ratios strengthen Ni-MCM-41 interactions, yielding highly dispersed Ni nanoparticles (4 nm vs. 6 nm for pristine Ni/MCM-41) and optimizing H₂ dissociation kinetics. The optimized Ni-30-MCM-41 catalyst demonstrates exceptional performance, that is, 1.7-fold higher hydrogenation activity than unmodified Ni/MCM-41, achieving full hydrogen storage capacity (5.8 wt%, 100%) in 120 min at 443 K. This dehydrogenation efficiency is comparable to commercial 3 wt% Pd/Al₂O₃. Crucially, the acid-modulated interface suppresses impurity gas generation (CH₄: <100 ppm vs. 400 ppm for Pd) by weakening C-C bond cleavage while maintaining high H₂ purity. This work establishes a structure-activity relationship between Brønsted acidity, MSI, and catalytic performance, offering a sustainable, noble metal-free paradigm for LOHC systems. The findings underscore the transformative potential of acidity-driven MSI engineering in designing next-generation catalysts for hydrogen energy applications.