The properties of nickel aluminate nanoparticles prepared by sol–gel and impregnation methods

Nickel aluminates were prepared by sol–gel and impregnation methods and calcined at 1100 °C. The sol–gel made samples were prepared with different amounts of nickel (Ni/Al molar ratio equal to 0, 0.25, 0.5, and 0.75) and aging times (24 and 48 h). The samples were characterized by X-ray diffraction, induced couple plasma, nitrogen physisorption, transmission and scanning electron microscopy, and ammonia temperature programmed desorption (NH3-TPD). In the sol–gel made samples, only the NiAl2O4 structure of nickel aluminate was defined, while for impregnation, NiAl10O16 was formed as well. The sol–gel made samples had low specific surface areas (7.7–12.4 m2/g), but a sample prepared by impregnation method had higher specific surface area (67.2 m2/g). The surface acidity density decreased by increasing the amount of nickel and was the lowest for impregnation method.