Evidence for the role of active hydrogen species in methanol synthesis over copper based catalysts

Cu-Zn-Al methanol synthesis catalysts have been studied by thermodesorption experiments in order to establish a correlation between catalytic activity and the concentration of active intermediates on the surface. It has been found that the methanol Synthesis activity not only depends on the concentration of formate species adsorbed on copper, but also on the amount of one particular type of hydrogen species favoured by ZnO and/or Cu-ZnO interaction. Thus the catalytic activity is related both to the copper metal surface area, and to the ability of the ZnO-Al2O3 oxide phase to generate and store active hydrogen species. This may explain the promoting or synergetic effect of ZnO on copper in methanol synthesis.