Triethylamine–Water as a Switchable Solvent for the Synthesis of Cu/ZnO Catalysts for Carbon Dioxide Hydrogenation to Methanol

Abstract Cu/ZnO catalyst precursors for industrial methanol synthesis catalysts are traditionally synthesised by coprecipitation. In this study, a new precipitation route has been investigated based on anti-solvent using switchable solvent system of triethylamine and water. This forms biphasic under nitrogen atmosphere can be switched to an ionic liquid single phase carbon dioxide atmosphere. When metal nitrate solutions were precipitated from water triethylamine–water as the hydroxynitrate phase, gerhardite, was formed, rather than hydroxycarbonate, malachite, formed calcined reduced, gerhardite which showed better productivity CO 2 hydrogenation traditional malachite precursor, despite their larger CuO crystallite size determined X-ray diffraction. The solvents could recovered switching after precipitation, allow recycling in process, reducing waste associated with synthesis.