K-promoted Pt/meso-Al2O3 catalysts for H2 production from dehydrogenation of dodecahydro‑N‑ethylcarbazole

N-ethylcarbazole, as a liquid organic hydrogen carrier, has shown great promise in the field of hydrogen storage technology. The development of efficient and stable catalyst for producing H₂ through N-ethylcarbazole dehydrogenation is crucial for its practical application. In this study, a series of mesoporous Al₂O₃-supported Pt catalysts with K modification were developed for N-ethylcarbazole dehydrogenation. These catalysts were characterization using various techniques including XRD, N₂ adsorption–desorption, TEM, ²⁷Al MAS NMR, XPS, NH₃-TPD, H₂-TPR, CO-FTIR, and Py-IR, providing detailed structural information to elucidate the structure–activity relationship. Mesoporous Al₂O₃ was found to possess significant amounts of coordinatively unsaturated pentacoordinate Al³⁺, which greatly promotes the dispersion of Pt species for the formation of small Pt particles. The addition of K was observed to modulate the electronic structure of Pt, reduce the acidity of the catalysts, and inhibit the sintering of Pt. These synergetic effects led to Pt_3.0/K_3.0-Al₂O₃-m achieving remarkable performance in dodecahydro-N-ethylcarbazole dehydrogenation at 180 °C and 101 kPa, delivering a dodecahydro-N-ethylcarbazole conversion of 100 %, H₂ release amount of 5.63 wt% and dehydrogenation efficiency of 97.10 %. Additionally, this catalyst demonstrated high efficiency in the dehydrogenation of dodecahydro-N-propylcarbazole, octahydro-2-methylindole, and octahydro-1,2-dimethylindole, achieving dehydrogenation efficiencies of 99.60 %, 100 % and 100 %, respectively. These findings provide valuable knowledge for the rational design of efficient metal-based catalysts for liquid organic hydrogen carriers in hydrogen storage systems.