Hydrogenation of N-propylcarbazole over supported ruthenium as a new prototype of liquid organic hydrogen carriers (LOHC)

We report full hydrogenation of N-propylcarbazole in molten state over a supported ruthenium catalyst at 120–150 °C. A remarkably fast reaction rate was achieved with the apparent activation energy of 18.4 kJ mol−1. Two stereoisomers of the final product were identified and the less stable one was found to dominate the product distribution at lower temperatures and/or with shorter reaction times, which is highly beneficial for hydrogen release upon dehydrogenation with better purity and for enhancement of catalyst performance. The optimum conditions for catalytic hydrogenation of N-propylcarbazole were found to be at 120 °C for 60 minutes.