Preparation and characterization of hydroxycarbonate precursors that yield successful alcohol synthesis catalysts

It is shown that Raman spectra and thermal analysis data (TGA and DSC) both discriminate among the hydroxycarbonate precursors that lead to successful Cu Zn - containing catalysts and those that lead to inactive catalysts. For binary Cu/Zn catalysts, the optimum precursor is single-phase three-dimensional aurichalcite, (Cu,Zn)5(OH)6(CO3)2, which is readily distinguished by these techniques from undesirable precursor materials such as copper hydroxynitrate [Cu2(OH)3NO3], rosasite [(Cu,Zn)2(OH)2CO3] and hydrozincite [Zn5(OH)6(CO3)2]. Ternary Cu Zn/Al catalysts are successfully made via a layer-structured hydrotalcite-like precursor, i.e., (Cu,Zn)6Al2(OH)16CO3·4H2O. Thermal decomposition and infrared analyses indicate that the interlayer carbonate anion is retained by the ternary catalyst even to calcination temperatures of 350–450 °C, which has implications for the subsequent aqueous surface doping treatments used to further promote these catalysts