Particle Shape Control of Zn-Al Composite Oxides by Using Composite Hydroxides as a Precursor

Zn-Al composite hydroxide by a co-precipitation method and its calcined products were prepared in different chemical composition. For the purpose of lowering calcination temperature and controlling particle morphology for ZnAl2O4 (spinel) synthesis, the obtained Zn-Al composite hydroxide was used as a precursor before a calcination operation. Zn-Al-CO3 LDH (Layered Double Hydroxide) is produced as a crystalline material in both chemical composition of spinel formation ([Zn2+]:[Al3+] = 1:2) and LDH formation ([Zn2+]:[Al3+] = 2:1). ZnAl2O4 is synthesized at lower calcination temperature of 700°C in the case of [Zn2+]:[Al3+] = 1:2. Zn-Al composite hydroxide with large plate-like particles is produced by applying a solvothermal treatment using ethylene glycol as a solvent to the Zn-Al composite hydroxide. When they are calcined, the composite oxide keeping the plate-like particle morphology of the precursor (Zn-Al LDH) is produced. It is clarified that ZnAl2O4 is synthesized at low temperature and the particle morphology is controlled by using Zn-Al LDH as a precursor.