Morphology-controlled synthesis of γ-Al₂O₃ with large mesopores through combustion of aluminum carboxylate salts

Aluminum carboxylate salts are synthesized by the reaction of aluminum isopropoxide and lower aliphatic acid. The crystalline structures and the morphologies can be easily controlled by tuning the organic acid used. When formic acid or acetic acid is used as both solvent and reactant, basic aluminum di-carboxylate can be obtained, while neutral aluminum tripropionate forms if propionic acid is used. And the morphological changes of the products are also investigated when the mixture of acetic and propionic acids with different ratios is used. After the calcination, all the aluminum carboxylates can transform to aluminas with the morphology retained. The thermal transformation process is monitored using TG-DTG, XRD and N₂ adsorption-desorption measurements. The resultant γ-Al₂O₃ displays a good textural properties (S_BET = 158 m² g^-1, V _total = 1.35 cm³ g^-1, d = 46 nm) and high thermal stability, where the γ-Al₂O₃ sample can endure calcination at 1000 C without any changes of crystalline structure.