Mechanism study on hydrogen generation from metal hydride coupled methanol steam reforming

Abstract

Metal hydride (MH) coupled methanol steam reforming (MSR), in which MSR is coupled by the hydrolysis of MH, is an attractive strategy for onsite hydrogen generation due to its high hydrogen density, high hydrogen purity and balanced thermal effect. This study provides a comprehensive mechanism study on MH coupled MSR on Cu/CaH2 by online mass spectroscopy with isotope labelling and in situ Fourier transformed infrared spectroscopy. The results show that hydrolysis of MH and MSR on Cu proceed simultaneously, following a formate-mediated pathway. The stepwise dehydrogenation of methanol primarily occurs on the Cu surface, while CaH2 effectively activates CH3OH at low temperature by supplying the hydrolysis heat to the endothermic MSR. Although Ca(OCH3)2 and Ca(HCOO)2 can be formed when CaH2 is presented, they are not active intermediates for the MH coupled MSR due to their high thermal stability. Instead, they will be converted back into CH3OH and HCOOH via hydrolysis.