CO2 hydrogenation on a metal hydride surface

Abstract

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.