The thermal stabilization mechanism of barium and the effects of preparation methods, barium content and calcination temperature were studied by BET specific surface area and powder X ray diffraction. It was found that barium can stabilize the alumina at high temperature (1000 ℃) and the stabilization effect was enhanced with the increase of the barium content, whereas, the overabundance weakened the stabilization effect. The preparation methods influenced the thermal stability of alumina and the stabilization effect of barium. At high temperature, the stabilization effect of barium species can be attributed to the dispersed baria and not hexaaluminate retarding the loss of specific surface area due to the sintering and αphase transformation within the initial 1 h of the calcination process.
The thermal stabilization mechanism of strontium and effect of preparation method on the thermal stability of Sr modified alumina and the stabilization effect of strontium species have been investigated by measuring the BET specific surface area and powder X ray diffraction. The results show that strontium species can stabilize the alumina at high temperature and the stabilization effect of the strontium species increases with the rise of strontium content, however, the overabundance of strontium species weakens its stabilization effect. The preparation method influences the thermal stability of alumina and stabilization effect of strontium. The thermal stability of Sr modified alumina prepared by sol gel method is superior to that of samples prepared by gelation and impregnation. At high temperature, it is probable that the dispersed strontium species instead of hexaaluminate stabilizes the alumina.
