物理化学学报 >> 1996, Vol. 12 >> Issue (11): 971-975.doi: 10.3866/PKU.WHXB19961103

研究论文 上一篇    下一篇

稀土修饰Al2O3的表面积热稳定性

赫崇衡,张文敏,汪仁   

  1. 安徽师范大学化学系,芜湖 241000|华东理工大学工业催化所,上海 200237
  • 收稿日期:1996-05-13 修回日期:1996-07-15 发布日期:1996-11-15
  • 通讯作者: 赫崇衡

Surface Area Stability of Aluminas Modified by Rare Earths

He Chong-Min,Zhang Wen-Min,Wang Ren   

  1. Department of Chemistry,Anhui Normal University,Wuhu 241000|Institute of Industrial Catalysis,East China University of Science and Technology,Shanghai 200237
  • Received:1996-05-13 Revised:1996-07-15 Published:1996-11-15
  • Contact: He Chong-Min

摘要:

以不同稀土元素为添加剂,采用浸渍法和捏和法制备了γ-Al2O3样品. 通过BET、XRD等手段,考察了在1273K湿空气中(含14kPa水蒸汽),经不同时间处理γ-Al2O3的相变和烧结情况,比较了各样品水热烧结后比表面积的差异,并分析了产生这种差异的原因.探讨了Al2O3的高温水热烧结动力学.根据所得动力学参数,讨论了烧结机理,并计算了烧结速率.

关键词: 稀土元素, 氧化铝, 比表面积, 热稳定性

Abstract:

 Surface modification with rare earths was investigated for improving the hydrothermal stability of γ-Al2O3. The rare earths were added by impregnation or kneading method. Among the rare earths, studied lanthanum is the most effective promoter for inhibiting the reduction of surface area of Al2O3 sintered in wet air(14kPa water vapor) at 1273K for 24h, because its cations with valence 3+ and proper ionic radii can insert into the crystal lattice of Al2O3 and prevent the transition of Al2O3 from sintering and transforming to α-Al2O3. The presence of vapor-phase water in sinter tests was found to have a pronounced effect on surface area of Al2O3. The XRD measurements show that the α-phase increases and the crystal sizes become larger as area decreases. The kinetics for sintering of Al2O3 was studied and the constants, n and k, were used to calculate the rate of area loss at given area level.

Key words: Rare earths, Alumina, Surface area, Thermal stability