Zn,Al hydrotalcites calcined at different temperatures: Preparation, characterization and photocatalytic activity in gas–solid regime

Layered double hydroxides (LDH) containing zinc and aluminium within the brucite-like layers and carbonate as the interlayer anion have been used as precursors for the preparation of mixed metal oxides by calcination. Zinc oxide and the ZnAl2O4 spinel were formed with different degree of crystallinity depending of two parameters, i.e., the Zn2+/Al3+ molar ratio and the calcination temperature (500-800ºC) of the LDH precursor. A pure spinel phase was obtained to remove ZnO upon a basic post-treatment in NaOH solution of the samples calcined at 800ºC. All the samples were tested for the photodegradation of 2-propanol in gas-solid regime. All the samples resulted active as heterogeneous photocatalysts. The photocatalytic activity increased by increasing the Zn2+/Al3+ molar ratio and the calcination temperature of the solids.