Synthesis and characterization of activated alumina with high thermal stability by a low-heat solid-phase precursor method

Abstract

Activated alumina has a porous structure and large specific surface area. It is often used as a catalyst carrier for various reactions. Currently, solution-phase methods (sol–gel reactions) that cause environmental pollution and resource waste are often used to synthesise activated alumina. To overcome this disadvantage, in this study, an eco-friendly low-heat solid-phase precursor method was developed to prepare activated alumina with improved properties (phase stability and specific surface area). The difference between the activated alumina synthesised by this method and a sol–gel method was studied in terms of the specific surface area and high thermal stability. The results indicated that after 4 h of treatment at 1100 °C, pure activated alumina obtained by the low-heat solid-phase precursor method maintained the γ-phase and had a specific surface area of 92 m 2 /g and pore volume of 0.68 cm 3 /g. On the other hand, pure activated alumina produced by the sol–gel method mainly consisted of the α-phase and had a specific surface area of only 21 m 2 /g and a low pore volume of 0.16 cm 3 /g. Upon doping with La and Ba, and heat-treating at 1100 °C for 4 h, the specific surface areas of the activated alumina samples obtained by the low-heat solid-phase precursor method and sol–gel methods were 109 and 119 m 2 /g, respectively. When heated at high temperatures, the percentage loss of the specific surface area of the activated alumina synthesised by the low-heat solid-phase precursor method was lower than that of the sample obtained by the sol–gel method, indicating that it can inhibit the crystal-phase transformation of alumina at high temperatures. • Activated alumina was synthesised by low-heat solid-phase precursor method. • Alumina synthesised by low-heat solid-phase precursor method has good high thermal stability. • Low-heat solid-phase precursor method is environmental and can synthesise porous materials.