Biodegradable Gelatin as Template for the Preparation of Mesoporous Alumina

Abstract

In this study, we propose a time‐ and energy‐saving method using biodegradable gelatin as a green template and a low‐toxicity inorganic aluminum salt (Al(NO3)3·9H2O) as a low‐cost aluminum source for the preparation of mesoporous alumina (γ‐Al2O3). The effects of pH (pH 8.0–10.0), gelatin to aluminum source ratio (0–1.9), and the hydrothermal treatment time (0–72 h) are thoroughly explored. The gelatin can assemble with the aluminum species γ‐AlOOH via hydrogen bonding to prevent the self‐condensation of the γ‐AlOOH during the hydrothermal treatment. Distinctly, the mesoporous γ‐Al2O3 was obtained from the calcination of the resulting gelatin–γ‐AlOOH composites. Without gelatin, high‐crystallinity γ‐AlOOH formed after the hydrothermal treatment, which transformed into the nonporous γ‐Al2O3 with a small surface area (20 m2/g). Finally, it was found that with a gelatin/aluminum ratio of 0.81, reaction pH value of 8.0, and hydrothermal treatment time of 24 h, high‐surface‐area mesoporous γ‐Al2O3 (262 m2/g) with pore diameter of 6.3 nm could be synthesized.