Thermally-Activated Al(OH)3: Phase Transformations and Porosity

Abstract

Thermochemically activated aluminum trihydroxide (Al (OH)3) is an important intermediate for ceramics, construction materials, catalysts, etc. Functional properties of materials based on Al (OH)3 depend on its phase composition and porosity. A series of thermochemically activated Al (OH)3 calcined at temperatures from 120 to 800 °C were studied by low-temperature N2 sorption, XRD and thermal analysis. It was shown that transformation of gibbsite to boehmite occurs below 300 °C and is accompanied by increasing of specific surface area and pore volume. Transformation of boehmite to γ-Al2O3 proceeds above 400 °C. The sample calcined at 500 °C was shown to consist of monophase γ-Al2O3 with specific surface area of 206 m2/g and pore volume of 0.55 cm3/g.