Synergistic catalysis of Ru single-atoms and zeolite boosts high-efficiency hydrogen storage

TLDR: In this paper , a Ru single atom supported on *BEA zeolite catalyst (Ru(Na)/Beta), with the assistance of hydrogen spillover, was used to accelerate the hydrogenation of N-ethyl carbazole (NEC), N-propylcarbazole(NPC), and 2-methylindole (2-MID).

Abstract: Liquid organic hydrogen carriers (LOHCs) are promising hydrogen carriers that play an important role in the hydrogen economy. However, designing an efficient catalyst for realizing hydrogen storage with cost-effective and low-temperature is still a great challenge. Herein, we report a Ru single-atoms supported on *BEA zeolite catalyst (Ru(Na)/Beta), with the assistance of hydrogen spillover, which can remarkably enhance the hydrogenation of N-ethylcarbazole(NEC), N-propylcarbazole(NPC) and 2-methylindole (2-MID) at lower temperatures with lower Ru content (0.5 wt%). Notably, the obtained Ru(Na)/Beta catalyst exhibits excellent activity in the hydrogenation of NEC with the hydrogen uptake of 5.69 wt% and a conversion rate of > 99% within 1.5 h for the 6 MPa H2 at 100 °C, whereas the hydrogen uptake on traditional Ru/Al2O3 is only 2.97 wt% with the conversion rate of 67 % under the same conditions. It is found that highly dispersed Ru single-atoms boost hydrogen activation and the strong acid sites (Brønsted and Lewis) of zeolites promote the hydrogen spillover on the hydrogenation with N-heterocycles. Moreover, the synergistic effect of Ru single atoms and *BEA zeolite is crucial for accelerating the hydrogenation rate and lowering the activation energy (45.7 vs. 88.3 kJ/mol) compared with traditional Ru-based catalysts.