Tuning the Performance of Ru–Pd Bimetallic Catalysts for Reversible Hydrogen Storage in N-Ethylcarbazole: A Comparative Study of γ-Al ₂ O ₃ , TiO ₂ , and MgAl-LDH Supports

The development of efficient and stable bifunctional catalysts is crucial for implementing liquid organic hydrogen carrier (LOHC) technology. This study investigates how the properties of three distinct catalyst supports, γ-Al2O3, TiO2, and MgAl-LDH, govern the activity and stability of Pd–Ru bimetallic catalysts for the reversible hydrogenation/dehydrogenation of N-ethylcarbazole (NEC). Comprehensive characterization reveals support-specific effects on the metal dispersion, electronic structure, and metal–support interaction. The Pd–Ru/γ-Al2O3 catalyst, benefiting from a high surface area, exhibits superior cyclic stability over five consecutive storage–release cycles. The catalytic performance of Pd–Ru/TiO2 is highly sensitive to the TiO2 crystal phase and reduction temperature, which control the Pd0/Ru0 ratio and the strength of the metal–support interaction. Notably, the Pd–Ru/MgAl-LDH catalyst, leveraging the unique layered structure and abundant hydroxyl groups of LDH, achieves ultrafine metal nanoparticle dispersion and shows the highest intrinsic dehydrogenation activity. This work elucidates the critical role of the support in modulating the physicochemical properties of bimetallic catalysts, providing a guideline for designing advanced catalytic systems for practical hydrogen storage and release.