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 (Cu0a-ZrO2 interfacial sites) compared with the other precursors.