Thermal stability of aluminas by hydrothermal treatment of an alkoxide-derived gel

摘要: Alumina precursors were prepared by hydrothermal treatment of alkoxide-derived alcogels. The crystalline structure precursor beohmites and their microstructural change during heat examined the specific surface area alumina after heating was measured. at 270 °C retained high areas temperatures; e.g. 35.0, 8.3 5.4 m2g−1 1200, 1400 1500 °C, respectively. thermal stability aluminas depended on temperatures. For excellent stability, following factors are necessary: (1) grain growth beohmite as an precursor, a size more than 20 nm for (1 2 0) plane; (2) crystallite (2 0 plane exceeding that (0 2) (3) anisotropic crystal. In transition region (≤ 1200 °C), is caused raising α transformation temperature, resulting from decreasing number boundaries growth. α-alumina (> inhibiting three-dimensional achieves preservation introduced into beohmite.