【摘要】 研究了氧化铝制备过程中的各种成胶条件 (氨水滴加速度 ,pH值 ,温度和硝酸铝溶液的初始浓度等 )对氧化铝热稳定性的影响 ,初步探讨了氧化铝的烧结机理 .结果表明 ,各种成胶条件均可在一定程度上影响氧化铝的比表面积、孔容和平均孔径 .选择适宜的制备条件能够阻止氧化铝在高温下烧结 ,改善氧化铝的孔结构 ,提高其热稳定性 ,从而制备出耐高温高比表面积的氧化铝更多还原

【Abstract】 Sintering is an important factor that causes the decrease of surface area of alumina at high temperature. This paper studies the effects of colloid forming conditions, such as drip feed rate of ammonia, pH value, temperature, and concentration of Al(NO 3) 3 solution, on the thermal stability of alumina prepared by the sol gel method and using La and Ba as the additives. The sintering mechanism of alumina is also discussed. The results show that the surface area, pore volume, and pore diameter of alumina vary obviously with the colloid forming conditions. Suitable conditions may prevent alumina from sintering at high temperature, increase the surface area of alumina, and improve the pore properties of alumina. The alumina prepared under the optimum conditions remains a surface area of 92 3 m 2/g after calcination at 1?100 ℃ for 20 h. The alumina sintering is found to be governed by two types of mechanisms, the viscous or plastic flow mechanism and the surface diffusion mechanism at the first stage and the second stage of the sintering, respectively.更多还原