ON THE MECHANISM OF THE METHANOL SYNTHESIS INVOLVING A CATALYST BASED ON ZIRCONIA SUPPORT

The nature of the pivotal intermediate during the synthesis of methanol from CO2/H-2, in the presence of ZnO/ZrO2 aerogel catalyst is envisaged. The kinetic studies performed using in situ FTIR spectroscopy of the species formed on the surface of the catalyst in the absence and in the presence of hydrogen show that the initial reactive adsorbed species formed from CO2 gas is the unidentate carbonate species. Its hydrogenation into the formate species is much faster than the hydrogenation of the formate species into methoxyl species. The comparison is based on a quantitative measurement of the rate constant of the hydrogenation of the various species. The results explain that during the CO2/H-2 reaction only formate and methoxyl species are observed.