Li Liu et al. have conducted a study entitled “Synergistic La₂O₃-La(OH)₃ Interface Engineering Enables Deep and Durable Dehydrogenation of 12H-N-Propylcarbazole over Pd/Al₂O₃ Catalysts”. This study was published in Frontiers of Chemical Science and Engineering, Volume 19, Issue 9, 2025.
Hydrogen, as a highly efficient, clean, and zero-carbon energy carrier, plays a crucial role in the global energy transition. However, challenges in its storage and transportation significantly limit its widespread application. Liquid organic hydrogen carriers (LOHCs) represent a breakthrough technology for hydrogen storage and delivery, among which 12H-N-propylcarbazole (12H-NPCZ) has attracted attention due to its high hydrogen storage capacity and moderate dehydrogenation conditions. Palladium (Pd) is the metal of choice for catalyzing the dehydrogenation of such compounds, and alumina (Al₂O₃) is commonly used as a support. Nevertheless, issues such as Pd nanoparticle agglomeration, insufficient catalytic activity, and poor stability need to be addressed, while lanthanum (La)-based promoters show potential in optimizing catalyst performance.The researchers prepared a series of alumina composite supports with varying La contents via a co-precipitation/hydrothermal route, and deposited Pd nanoparticles to obtain Pd/LaₓAlO catalysts. Comprehensive characterization and 12H-NPCZ dehydrogenation performance tests were carried out. The results showed that an optimal 10 wt% La loading led to the formation of intimately interfaced La₂O₃ and La(OH)₃ nanodomains on the support surface, which anchored highly dispersed Pd particles (~2.2 nm), donated electrons to Pd⁰, and constructed bifunctional acid-base sites along with a fast hydrogen-spillover network. The Pd/La₁₀AlO catalyst achieved the theoretical H₂ release (5.43 wt%) within 150 minutes at 180 °C, with 99% NPCZ selectivity and no activity loss over ten cycles. Kinetic analysis revealed that La doping significantly reduced the apparent activation energies of the three successive dehydrogenation steps, with a ~65 kJ·mo-1drop in the rate-limiting 4H-NPCZ→NPCZ stage.This study provides the first mechanistic evidence that the coexistence of La₂O₃ and La(OH)₃ can cooperatively tune the electronic and interfacial structure of Pd/Al₂O₃, offering clear guidelines for designing efficient and stable dehydrogenation catalysts for N-heterocyclic LOHCs.
For more detailed information, the full paper is available at: https://doi.org/10.1007/s11705-025-2599-1.