CO2 hydrogenation on a metal hydride surface

The catalytic hydrogenation of CO2 at the surface of a metal hydride and the corresponding surface segregation were investigated. The surface processes on Mg2NiH4 were analyzed by in situ X-ray photoelectron spectroscopy (XPS) combined with thermal desorption spectroscopy (TDS) and mass spectrometry (MS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). CO2 hydrogenation on the hydride surface during hydrogen desorption was analyzed by catalytic activity measurement with a flow reactor, a gas chromatograph (GC) and MS. We conclude that for the CO2 methanation reaction, the dissociation of H2 molecules at the surface is not the rate controlling step but the dissociative adsorption of CO2 molecules on the hydride surface.