Acta Phys. -Chim. Sin. ›› 2004, Vol. 20 ›› Issue (07): 717-721.doi: 10.3866/PKU.WHXB20040710

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Hydrothrmal Crystal Growth of Very Light Boehmite products

Cai Wei-Quan;Li Hui-Quan;Zhang Yi   

  1. Institute of Process Engineering, the Key Laboratory of Green Process Engineering, Chinese Academy of Sciences, Beijing 100080;Graduate School of the Chinese Academy of Sciences, Beijing 100039
  • Received:2003-12-19 Revised:2004-03-04 Published:2004-07-15
  • Contact: Cai Wei-Quan E-mail:wqcai@home.ipe.ac.cn

Abstract: The hydrothermal precipitation in the Al2(SO4)3-CO(NH2)2-H2O system under the conditions of [Al3+]=0.2 mol•L-1,[CO(NH2)2]:[Al3+]=2:1 and 2 h at different temperatures has been studied. Very light boehmite powders in the form of porous agglomeration of several micron size covered with needle clusters are obtained at above 140 ℃.The reaction solution and the products are characterized by ICP-AES, XRD, FT-IR, SEM, BET and particle size distribution. The precipitation of aluminum hydroxide gel or amorphous powder is almost completed at 140 ℃. With the reaction temperature raised to 180 ℃, crystallinity of the products, whose tap density varies among 117.2~158.2 kg•m-3,becomes more perfect and the specific surface area increases from 75.3 m2•g-1 to 88.3 m2•g-1 as well. However, the average diameter decreases moderately. The γ-Al2O3 powders formed by calcination of aforementioned boehmites at 550 ℃ for 2 h have the same shape and higher specific surface area compared with their corresponding precursors.

Key words: Very light boehmite, Hydrothermal synthesis, Uniform precipitation,  Crystal growth, γ-Al2O3