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Highly dispersed Pd nanoparticles immobilized in MIL-101 (Pd@MIL-101) were prepared and used for the catalytic dehydrogenation of Liquid organic hydrogen carriers (LOHC). The as-synthesized catalysts were characterized and it was found that 3 wt% of Pd@MIL-101 embodied smaller and highly dispersed Pd NPs. The catalytic activities of as-synthesized catalysts were investigated by the dehydrogenation of a representative LOHC compound, perhydro-N-propylcarbazole (12H-NPCZ). The results indicated that 3 wt% Pd@MIL-101 catalyst exhibited good catalytic activity and good reusability for the dehydrogenation of 12H-NPCZ, which is superior to that of commercial 5 wt% Pd/Al 2 O 3 catalyst. This study demonstrates that Pd@MIL-101 is a promising dehydrogenation catalyst for the application of LOHC technology. Image 1 • Highly dispersed Pd NPs immobilized in MIL-101 (Pd@MIL-101) were prepared. • 3 wt% catalyst exhibits better catalytic activity than commercial 5 wt% Pd/Al 2 O 3. • Pd@MIL-101 shows good reusability for the catalytic dehydrogenation of 12H-NPCZ. [ABSTRACT FROM AUTHOR]

Abstracts We report a new candidate of liquid organic hydrogen carrier, 1-methylindole, with a hydrogen content of 5.76 wt% and a low melting point of below −20 °C. The hydrogenation of 1-methylindole and the dehydrogenation of octahydro-1-methylindole were investigated in details. Full hydrogenation of 1-methylindole was realized over a 5 wt% Ru/Al 2 O 3 catalyst at 130 °C and 6.0 MPa, and both conversion and selectivity of 100% towards octahydro-1-methylindole were achieved. The catalytic dehydrogenation of octahydro-1-methylindole was carried out over a 5 wt% Pd/Al 2 O 3 catalyst. By using a combined experimental and density functional theory approach, the mechanism of octahydro-1-methylindole dehydrogenation to 1-methylindole and the two stable isomers of octahydro-1-methylindole were analyzed. The effect of reaction temperature and dosage of catalyst on the hydrogen release content were systematically studied. In addition, the dehydrogenation of octahydro-1-methylindole at 160–190 °C on Pd/Al 2 O 3 was well described by a first-order stepwise dehydrogenation reaction with the apparent activation energy of 122.99 kJ/mol. The purity of released H 2 was higher than 99.99% with no detectable impurity. [ABSTRACT FROM AUTHOR]

Hydrogenation of N-ethylindole was investigated over a 5 wt% Ru/Al 2 O 3 catalyst in the temperature range of 160–190 °C at 9 MPa. The process was found to undergo the sequential steps of N-ethylindole → 2H-N-ethylindole → 4H-N-ethylindole → 8H-N-ethylindole with rapid consumption of all intermediate species. The reverse process, dehydrogenation of octahydro-N-ethylindole, was subsequently conducted for tests over a 5 wt% Pd/Al 2 O 3 catalyst in the same temperature range. Full dehydrogenation can be achieved with a moderate reaction rate. The released H 2 gas was found to be of a high purity. Our results indicate that N-ethylindole is a promising new member of liquid organic hydrogen carrier family. [ABSTRACT FROM AUTHOR]

N-ethylcarbazole is one of the most promising liquid organic hydrogen carriers (LOHCs) as it can be catalytically hydrogenated and dehydrogenated at relatively moderate temperatures. In the present work, we report a systematic study on dehydrogenation of perhydro-N-ethylcarbazole over several important supported noble metal catalysts to identify the optimal catalyst for temperature-controlled dehydrogenation. The reaction takes three consecutive stages with two intermediates of octahydro-N-ethylcarbazole and tetrahydro-N-ethylcarbazole. The initial catalytic activity of the selected noble metal catalysts for the dehydrogenation process was found to follow the order of Pd > Pt > Ru > Rh. 100% selectivity toward the final product of N-ethylcarbazole and fully dehydrogenation was achieved over the supported Pt and Pd catalysts. The kinetics of the three stage dehydrogenation processes over the catalysts was studied and the rate constants were derived. The results indicate that the dehydrogenation reaction rate decreases significantly with the reaction stage for all the selected noble catalysts and the conversion from tetrahydro-N-ethylcarbazole to N-ethylcarbazole was found to be the rate-limiting step of the entire reaction process. [ABSTRACT FROM AUTHOR]