Effects of Cu Precursor Types on the Catalytic Activity of Cu/ZrO2 toward Methanol Synthesis via CO2 Hydrogenation

This paper presents the influence of different types of copper precursors on CO2-to-methanol hydrogenation over copper nanoparticles on amorphous ZrO2. Here, we chose copper nitrate hydrate, copper acetate hydrate, and a copper ammine complex as the precursor. A copper-acetate-based catalyst, which was precalcined at 350 °C, was more active and selective toward methanol than were the other catalysts. Regardless of the different copper precursors, after calcining a mixture of a copper precursor and amorphous ZrO2 at 350 °C, surface-dispersed Cu2+ species (CuO4 square planes) were partly formed on amorphous ZrO2. The Cu2+ species was reduced by H2 to form Cu0 nanoparticles (<5 nm). This paper reports that using copper acetate monohydrate as a copper precursor leads to the greater number of active sites (Cu0—a-ZrO2 interfacial sites) compared with the other precursors.