On the acid–base properties of Zn–Mg–Al mixed oxides Original Research Article

The influence of Zn2+ cation substitution in Mg–Al mixed oxides is explored in the Zn2+ concentration range from 20 to 60 mol%. The mixed oxides are derived by calcination of layered double hydroxide precursors. Structural analyses by XRD and 27Al MAS NMR show that Al3+, Mg2+ and Zn2+ cations are well dispersed among the oxide phases. The acid site concentration increases with increasing zinc content, while the concentration of basic sites decreases compared to Zn2+ free mixed oxides. Acetone is the primary reaction product of propan-2-ol elimination with all zinc containing oxides. This suggests that the high activity for dehydrogenation of propan-2-ol is related to the pronounced hydride abstraction ability of Zn2+ cations and not to an enhanced strength or concentration of basic sites.