Hydrogenation of N-ethylcarbazole with Hydrogen-Methane mixtures for hydrogen storage

•The optimal hydrogenation temperature of NEC is 443 K.•The 8H-NEC to 12H-NEC step is extremely slow and this step is unstable at 453 K with generation of by-products.•N-ethylcarbazole can achieve hydrogen storage in a hydrogen-methane mixture by selectively catalytic reaction.•The addition of methane can increase the degree of hydrogenation.