Investigation of the effect of lanthanum oxide on the thermal stability of alumina aerogel

Monolithic alumina aerogels were prepared with inorganic aluminum salts as raw material by epoxide-assisted sol–gel method. The structure and morphology of the monolithic alumina aerogels doped with different lanthanum oxide concentration were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption–desorption method and field emission scanning electron microscope. The results indicate that the pure alumina aerogel is translucent and sky blue in color. Alumina aerogels gradually changes into opaque blocks of ivory with increasing the amount of lanthanum oxide. The addition of lanthanum oxide can increase the specific surface area of alumina aerogels and improve their thermal stability at high calcination temperature. After calcination at 1000 °C for 2 h, alumina aerogel doped with 10 wt% lanthanum oxide is still amorphous phase and its specific surface area can reach 282 m2/g, which is much higher than pure alumina aerogel.