Hydrothermal crystallization of boehmite from freshly precipitated aluminium hydroxide

Hydrothermal crystallization of boehmite from freshly precipitated aluminium hydroxide was monitored using X-ray powder diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Crystallite sizes and interplanar spacings for boehmite samples were determined. Changes in the crystallinity of boehmite influenced the corresponding FT-IR spectra, The maximum specific area for boehmite powder was 246 m(2) g(-1). as measured by the Brunauer-Emmet-Teller (BET) method. With an increase of the crystallinity of boehmite, the specific area decreased and for the best crystalline sample, was 91 m(2) g(-1). All boehmite samples contained particles of colloidal dimensions. For the best crystalline boehmite sample, hexagonal-like plates were observed and some of them were elongated. (C) 1999 Elsevier Science B.V. All rights reserved.