Catalytic activity of the M/(3ZnO.ZrO2) system (M = Cu, Ag, Au) in the hydrogenation of CO2 to methanol

Morphology, surface composition, dispersion of the metals were determined for a series of the M/(3ZnO * ZrO2) catalysts (M = Cu, Ag, Au) with the use of the XPS, XRD and TEM techniques. Catalytic activity in the reaction of the synthesis of methanol from CO2 was also determined. The catalysts contain crystallites of ZnO and amorphous ZrO2, and they show a considerable segregation of the components. The surface is depleted of the metal, metallic Cu is present mainly in the surrounding of ZnO. In the catalysts containing gold and silver, Au and Ag are distributed more uniformly. The dispersion of the metals in the catalysts depends on the nature of the metal and decreases in the series Au approx Cu > Ag, and for a given metal it decreases with the increase in the metal content. The catalysts containing copper exhibit by far higher catalytic activity when compared to the catalysts containing Ag and Au, due to a synergy between Cu and ZnO or ZrO2.