INS investigation of hydrogen on a copper catalyst

Hydrogen is a crucial component in methanol synthesis. It is widely believed that H2 dissociates on the copper. The hydrogen atoms then migrate to adsorbed CO or CO2 and progressively hydrogenate it to methanol. However, there is no direct evidence for adsorbed hydrogen on copper. Temperature programmed desorption measurements (TPD) shows that hydrogen is desorbed from Cu nanoparticles around 320 K, TPD of the methanol synthesis catalyst, Cu/ZnO/Al2O3, shows desorption peaks at ~300 and ~450 K. The 300 K peak is assigned to a surface hydride and the 450 K peak to subsurface hydrogen. Neither of these species has been detected by spectroscopy. Inelastic neutron scattering with its particular sensitivity to hydrogen is the ideal tool to investigate the state of hydrogen on/in a catalyst. We propose to use INS to study hydrogen on Cu nanoparticles and also the methanol synthesis catalyst, Cu/ZnO/Al2O3.