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

• Basic di-carboxylate and neutral tri-carboxylate salts were synthesized.
• The influence of organic acid used to the sample morphology was investigated.
• All the aluminum carboxylate salts can pseudomorphically transform to aluminas.
• γ-Al2O3 displays a significantly high pore volume and high thermal stability.
• The alumina particle sizes and aggregation degrees greatly affect the sintering.

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 (SBET = 158 m2 g−1, Vtotal = 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.

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