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 Cu nanoparticles (<5 nm). This paper reports that using copper acetate monohydrate as a copper precursor leads to the greater number of active sites (Cu-a-ZrO₂ interfacial sites) compared with the other precursors.