Facile Synthesis of Mesoporous Aluminum Oxides Using an Aqueous NaAlO2 Solution

초록

Aluminum hydroxides have been investigated for scientific and industrial application such as catalysts, sorbents, ceramics, and supporting materials. Various synthetic methods for mesoporous aluminum oxides have been reported in the literature including the template-based synthesis, emulsion process, and hydrothermal process. We have studied the preparation of mesoporous materials using a template-free solution route from a sodium aluminate (NaAlO2) precursor. Aluminum oxides with various internal and external structures could be prepared by controlling reaction conditions such as reactant concentrations, reaction temperature/time, and dropping rate. First, amorphous spherical particles were prepared at 12℃ when the dropping rate was 0.57mL/sec. These amorphous particles could be converted to γ-Al2O3 spherical particles with the calcination at 900℃. The BET surface areas were 64 m2g-1 for as-prepared particles and 96.6 m2g-1 for calcined ones. Secondly, urchin-shaped AlOOH hollow particles were obtained when the reaction temperature was raised to 60℃. This materials could be transferred to γ-Al2O3 particles after the calcination at 700℃. The BET surface areas were found to be 192 m2g-1 for as-prepared particles and 266 m2g-1 for calcined ones. The pore size was 6.2 nm for as-prepared, 3.7 nm and 7.6 nm for calcined particles.