Integration of Hydrogenation and Dehydrogenation Based on N-Ethylcarbazole as a Liquid Organic Hydrogen Carrier

N-Ethylcarbazole (NEC), as a novel liquid organic hydrogen carrier (LOHC), has presented superiority to lower hydrogen storage cycle temperature and acceptable hydrogen storage capacity compared to benzene/toluene, etc. However, there is a lack of optimization of reaction conditions and cyclic testing for further commercial applications. Herein, we optimized the hydrogenation and dehydrogenation reaction conditions to obtain higher hydrogen storage capacity based on NEC/12H-NEC. The results revealed that 99.0% hydrogenation percentage and 91.7% dehydrogenation percentage could be available over Pd-based catalysts under optimal conditions. The cycling tests of the NEC-based hydrogenation and dehydrogenation reactions exhibited the desired stability after six cycles. Process simulation had been performed for the integration of NEC's hydrogen storage unit in hydrogen vehicles, demonstrating that the actual hydrogen storage capacity of 5.3% and the energy output efficiency of 66% can be achieved. This work demonstrated the potential of the NEC/12H-NEC system for commercial applications.