Role of hydrogen spillover on the hydrogenation of N-ethylcarbazole over in-situ Encapsulation of Ru within zeolite for hydrogen storage

Hydrogen spillover plays a crucial role in heterogeneous catalysis, significantly enhancing the activity of catalysts. However, the promotion mechanism of hydrogen spillover on non-reducible oxide supports (such as zeolite) is rarely reported. Herein, we prepared Ru@Beta sample by in-situ approach, effectively encapsulating Ru species into Beta zeolite. Additionally, three samples (Ru/SiO2, Ru@Na(3, and Ru@H(3) with different hydrogen spillover effect were prepared. The optimal concentration of Ru was 0.5 wt%, and the Ru@H(3 sample with the strongest hydrogen spillover has 100 % conversion rate of N-ethylcarbazole (NEC) and 98 % selectivity towards to 12H-NEC. In contrast, the Ru/SiO2 with weak hydrogen spillover has only 89.5 % conversion rate and 28.9 % selectivity of 12H-NEC. Notably, the Ru@H(3 can still completely convert NEC even after 7 cycles, thereby exhibiting its remarkable activity and stability. Various characterizations (HAADF-STEM, XPS, EXAFS, in-situ DRIFT, and H2-TPD) indicate the superior catalytic performance of Ru@H(3 with strong hydrogen spillover effect, originating from the presence of more hydroxyl (-OH) and Br & oslash;nsted acid on the surface, while Lewis acid act as hydrogen acceptors and NEC hydrogenation sites. This work not only expands our understanding of the hydrogen spillover, but also paves the way onto the potential applications in heterogeneous catalysis for efficient hydrogenation.