Mechanochemical Effect in Mixing Sponge Copper with Amorphous ZrO₂ Creates Effective Active Sites for Methanol Synthesis by CO₂ Hydrogenation

For efficient methanol synthesis by CO2 hydrogenation, catalysts prepared by mixing sponge copper and amorphous ZrO2 were investigated. The commercial sponge copper itself exhibited catalytic activity for methanol synthesis by CO2 hydrogenation. The sponge copper mixed with amorphous ZrO2 in a mortar showed higher catalytic activity. Moreover, both CO2 conversion and methanol selectivity were enhanced by wet milling using a planetary ball mill. Taking into consideration the structure, we found a mechanochemical interaction between the sponge copper and amorphous ZrO2 by wet milling. These results showed that the strong interaction between the sponge copper and amorphous ZrO2 caused by the mechanochemical treatment creates effective sites for methanol synthesis by CO2 hydrogenation.