Kinetics of H2 recovery from dodecahydro-N-ethylcarbazole over a supported Pd catalyst

The dehydrogenation kinetics of dodecahydro-N-ethylcarbazole, a candidate H2 storage compound with a storage capacity of 5.8 wt.%, is reported. Dodecahydro-N-ethylcarbazole was produced by hydrogenation of N-ethylcarbazole over a supported Ru catalyst at 7 MPa and 130–150 °C. The hydrogenation followed first-order kinetics with an apparent activation energy of 99.5 kJ/mol. A storage capacity of 5.3 wt.% H2 was achieved. Dehydrogenation of the dodecahydro-N-ethylcarbazole, measured over a supported Pd catalyst at 101 kPa and 150–170 °C, also followed first-order kinetics with an apparent activation energy of 126.7 kJ/mol, proceeding to 100% conversion and a maximum 69% recovery of the stored H2 at 170 °C. The ethyl group of N-ethylcarbazole prevented strong product adsorption via N so that catalyst deactivation that was observed over Pd during the dehydrogenation of 1,2,3,4-tetrahydrocarbazole, an alternative H2 carrier, did not occur.