Sulfur-Doped Al₂O₃ for tuning catalyst surface properties to enhance the dehydrogenation performance of Dodecahydro-N-Ethylcarbazole

The N-ethylcarbazole/dodecahydro-N-ethylcarbazole (NEC/12H-NEC) system has emerged as one of the most promising hydrogen storage carriers due to its excellent hydrogen storage performance. However, its dehydrogenation process remains a bottleneck that hinders its further development. In this study, a series of Pt/Al2O3-x S-T catalysts were prepared by hydrogen reduction. The effects of sulfur doping levels and reduction temperature on the surface properties and structure of the catalysts were systematically investigated, followed by an examination of their impact on the dehydrogenation activity and selectivity of 12H-NEC. The results show that the 0.5 wt% Pt/Al2O3-0.5 S-473 catalyst exhibits the best dehydrogenation performance, with H2 release of 5.74 wt% and specific activity is 207.78 mmol H2·gPt-1min-1 after 7 h at 453 K. The introduction of trace sulfur not only optimizes the metal particle size and electronic structure of Pt but also promotes reactant adsorption and C-H bond activation by adjusting the content of acidic sites on the catalyst surface, thereby enhancing dehydrogenation activity. Regulating the strengths of acidity and basicity facilitates the desorption of products, thereby inhibiting C-N bond cleavage reactions and ultimately achieving highly efficient and highly selective catalytic performance in dehydrogenation. This study reveals the critical role of acid-base regulation in enhancing the activity, selectivity, and stability of LOHC catalysts, providing both theoretical insights and practical guidance for the design and development of highly efficient dehydrogenation catalysts.