Characterization of mesoporous alumina particles prepared by spray pyrolysis of Al(NO3)2·9H2O precursor: Effect of CTAB and urea

Mesoporous alumina particles with spherical shape were prepared by spray pyrolysis of Al(NO3)2·9H2O precursor. The surface area and the mesopores structure were investigated with varying the concentration of surfactant (cetyltrimethylammonium bromide, CTAB) and urea. The surface area and pore volume of alumina particles prepared by spray pyrolysis was greatly influenced by the CTAB/Al ratio, whereas, no significant change in the average pore size (3 ± 0.2 nm) was observed. According to the small-angle X-ray spectrum (SAXS) analysis, the prepared alumina had warm-like mesostructure. The d-spacing was slightly changed with varying the CTAB/Al ratio and correlated to the BET surface area and the number of CTAB micelles involved in making mesopores. It was found that the use of urea additive in the spray solution is helpful to increase the surface of alumina particles as well as the SAXS peak intensity due to the formation of mesostructures. In terms of the surface area and the pore regularity, the optimal CTAB/Al ratio and urea concentration was 0.1 and 3.0 M, respectively.