Pd-modified LaNi5 nanoparticles for efficient hydrogen storage in a carbazole type liquid organic hydrogen carrier

Abstract

In this work, we report the synthesis and catalytical property of a palladium catalyst loaded on a hydrogen storage support-Pd/LaNi5 in reversible hydrogen storage of N-ethylcarbazole (NEC). We prepare LaNi5 nanoparticles by the molten salt reduction method and use galvanic replacement to deposit a thin Pd layer on the surface. Catalyzed by 1 wt%Pd/LaNi5, NEC absorbs 5.5 wt% H2 in 0.7 h at 453 K and 7 MPa H2, and perhydro-NEC desorbs 5.5 wt% in 2.1 h at 473 K and 0.1 MPa H2, which significantly outperforms Pd/Al2O3 catalyst with the same Pd loading. The significantly promoted catalytic performance is attributed to the ample lattice hydrogen bonding sites and fast bulk hydrogen diffusion kinetics of LaNi5, which breaks the limitation of active hydrogen bonding sites due to the competitive adsorption of hydrogen and the organic molecule in surface catalysis. The active role of the lattice hydrogen bonding sites makes hydrogen storage materials highly attractive for hydrogen-related catalysis