Abstract: The thermal stabilization mechanism of Al2O3 modified by alkaline earths using impregnation method with various contents and calculation time was studied by BET surface area and powder X-ray diffraction.It was found that the addition of alkaline earths increased the surface area of Al2O3 and retarded the transforming into α phase.The stabilization effect was enhanced with the increase of the alkaline earths contents,whereas,the overabundance weakened the stabilization effect.Among the alkaline earths,strontium and calcium are the most effective promoters for inhibiting the reduction of surface area of Al2O3 sintered in air at 1 373K for 10 h.The study of the kinetics behavior of Al2O3 at 1 373K indicated that the stabilization of Al2O3 due to strontium and calcium was mainly attributed to that the alkaline earths played the retarding role of the sintering and α phase transformation within initial 1h during the calcination process.It was the dispersed oxide of alkaline earths but not aluminate that resulted in the stabilization of Al2O3 at high temperature.

Key words: Alumina, Surface area thermal stability, Alkaline earths, Modification