A THEORETICAL-STUDY FOR THE CO2 HYDROGENATION MECHANISM ON CU/ZNO CATALYST

Ab initio MO calculations were carried out for the CO2 hydrogenation on Cu/ZnO catalyst. The probable intermediates on Cu-0, Cu+, and Zn+ have been identified and it was found that the methanol synthesis proceeded mainly on Cu+ as follows; CO2-->CO2(ad.)-->bridging-formate-->formaldehyde-type complex-->methoxy-->methanol. The required energies of each elementary step was below 44 kJ/mol and this route seems to proceed with ease. Vibrational frequencies for the hydrogenation intermediates were also calculated. The calculated frequencies were in good agreement with the FT-IR experimental results.