COPPER-ZIRCONIA CATALYSTS FOR METHANOL SYNTHESIS FROM CARBON-DIOXIDE - EFFECT OF ZNO ADDITION TO CU-ZRO2 CATALYSTS

Coprecipitated Cu-ZrO2 catalysts were found to show higher selectivity to methanol in CO2 hydrogenation than conventional Cu-ZnO catalysts. Addition of ZnO to Cu-ZrO2 catalysts of Cu/ZrO2 = 1 (weight ratio) greatly enhanced the activity at lower temperatures, while keeping the high methanol selectivity of Cu-ZrO2 catalysts. A remarkable increase in the Cu dispersion with increased amount of added ZnO explains the increased activity at lower temperatures, while the reforming of methanol to CO is accelerated by ZnO at higher temperatures, leading to a lowered yield of methanol. It is suggested that ZrO2 rather than ZnO in the ternary systems plays a more effective role for the selective formation of methanol.