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 precipitation using a switchable solvent system of triethylamine and water. This system forms a biphasic system under a nitrogen atmosphere and can be switched to an ionic liquid single phase under a carbon dioxide atmosphere. When metal nitrate solutions were precipitated from water using triethylamine–water as the anti-solvent a hydroxynitrate phase, gerhardite, was formed, rather than the hydroxycarbonate, malachite, formed by coprecipitation. When calcined and reduced, the gerhardite precursors formed Cu/ZnO catalysts which showed better productivity for methanol synthesis from CO₂ hydrogenation than a traditional malachite precursor, despite their larger CuO crystallite size determined by X-ray diffraction. The solvents could be recovered by switching to the biphasic system after precipitation, to allow solvent recycling in the process, reducing waste associated with the catalyst synthesis.

用于工业甲醇合成催化剂的 Cu/ZnO 催化剂前体传统上是通过共沉淀法合成的。在这项研究中，基于使用三乙胺和水的可转换溶剂系统的反溶剂沉淀，研究了一种新的沉淀路线。该体系在氮气氛下形成双相体系，在二氧化碳气氛下可转变为离子液体单相。当使用三乙胺-水作为反溶剂从水中沉淀出金属硝酸盐溶液时，会形成羟基硝酸盐相，即gerhardite，而不是通过共沉淀形成的羟基碳酸盐，孔雀石。当煅烧和还原时，黄铜矿前驱体形成了 Cu/ZnO 催化剂，显示出更好的从 CO ₂合成甲醇的生产率尽管 X 射线衍射测定的 CuO 微晶尺寸更大，但与传统的孔雀石前驱体相比，氢化反应更明显。可以通过在沉淀后切换到双相系统来回收溶剂，以便在过程中回收溶剂，减少与催化剂合成相关的浪费。