Meso- and nano-structuring of industrial Cu/ZnO/(Al2O3) catalysts

A concept is presented, which helps to rationalize the success of the industrially applied preparation route for Cu/ZnO/(Al2O3) catalysts. Many studies can be found in the open literature, which describe the critical dependency of the final catalyst’s properties on precursor chemistry. In line with previous reports, this concept identifies zincian malachite as the relevant precursor phase and includes a simple relation of precursor crystal structure and final Cu surface area. It comprises two hierarchical microstructure-directing effects, for which particle morphology and degree of Cu2+ substitution by Zn2+ in the zincian malachite phase are the key properties: (i) meso-structuring of the precursor phase upon ageing of the co-precipitate in the mother liquor and (ii) nano-structuring of the oxide phase upon decomposition. Consequences for further optimization of the Cu, Zn, Al system are discussed.