Preparation of Active Alpha-Alumina Powder by the Thermal Decomposition of Diaspore

点击翻译按钮获取中文摘要

1. An acicular single crystal of diaspore (betaーAl_2O_3・H_2O) (width <lmum, length <10mum) was synthesized under the conditions of 1N NaOH, 450^ﾟC and 1200kg/cm^2 and characterized by means of XRD, SEM, ED, IR and ^<27>A1 MASNMR.2. Dehydration kinetics of diaspore fitted Avrami-Erofeev equation which derived from nucleation-growth controlled process.3. Diaspore showed a DTA endothermic peak due to the dehydration at 490^ﾟC and transformed directly to alpha-Al_2O_3. Even on heating to 1300^ﾟC, the original external shape of diaspore crystal was not destroyed, which indicated that diaspore transformed topotactically toalp ha-Al_2O_3.4. Specific surface areas of diaspore and resulting alpha-Al_2O_3 at 530^ﾟC were 4 and 70 m^2/g. alpha-Al_2O_3 did not show any catalytic activity for the isomerization of 1-butene to 2-butene, in spite of the large surface area.5. Application of acicular alpha-Al_2O_3 particles obtained from diaspore as an abvanced new material is investigated.