钡对氧化铝的高温热稳定作用

在汽车正常工作状况下汽车催化剂所处的氛围常高达１０００℃ ,这就要求催化剂有较高的热稳定性．催化剂的热稳定性除了依赖于活性组分的耐热性能外 ,还取决于涂层（γ Ａｌ２Ｏ３）的热稳定性 ,因此提高γ Ａｌ２Ｏ３ 涂层的高温耐热性非常重要．研究表明 ,Ａｌ２Ｏ３ 前驱体的结构、颗粒度及制备方法可以影响γ Ａｌ２Ｏ３ 涂层的比表面积和热稳定性 ［１ -３］,而在涂层中引入某些添加剂 ,如稀土氧化物Ｌａ２Ｏ３、碱土氧化物ＢａＯ、ＳｒＯ等对提高Ａｌ２Ｏ３ 的热稳定性更有效［４ -７］．其中 ,Ｌａ２Ｏ３ 除了抑制Ａｌ２Ｏ３ 的表相…

Thermal Stabilization of Barium on the Alumina at High Temperature

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 α phase transformation within the initial 1 h of the calcination process.