The role of CO₂ dissociation in CO₂ hydrogenation to ethanol on CoCu/silica catalysts

CoCu-based catalysts are widely used in CO_x hydrogenation reactions to produce higher alcohols due to the C–C coupling ability of Co and the ability of Cu to produce alcohols. This work describes the role of easily happened CO₂ dissociation on the CoCu surface during the reaction, using different silica support to tune the metal–support interaction, and reaches different selectivity to ethanol. CoCu supported on mesoporous silica MCM-41 shows ethanol selectivity as high as 85.3%, and the ethanol space-time yield (STY) is 0.229 mmol/(g_metal∙h), however, poor selectivity to ethanol as low as 28.8% is observed on CoCu supported on amorphous silica. The different selectivity is due to the different intensities of CO₂ dissociation on the catalysts. The adsorbed O* produced via CO₂ dissociation can occupy the cobalt hollow sites on CoCu surfaces, which are also the adsorption sites of C₁ intermediates for further C–C coupling.