Effects of hydrogen at high temperature on ZnAl2O4 and Sn−ZnAl2O4

ZnAl₂O₄ and Sn?ZnAl₂O₄ were synthesized by coprecipitation, sol-gel and impregnation methods. These materials were calcined and treated in H₂ at 1073 K. Thermal analysis (DTA and TG), nitrogen physisorption (BET method), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used as characterization techniques. H₂ treatment promoted Al_xZn_y crystallization in the coprecipitated and impregnated samples. When tin was added to zinc aluminate, the tin acted as a protective shell against high-temperature reduction, independently of the preparation technique.