Self‐assembled γ‐Al2O3 with hierarchical structure was successfully obtained via thermolysis of γ‐boehmite (γ‐AlOOH) particles, which was hydrothermally derived from aluminum ammonium sulfate hydrate (NH4Al(SO4)2·12H2O), urea, poly‐glycol (PEG)‐2000, and deionized water. SEM observations indicate that the as‐synthesized γ‐AlOOH has hierarchical flower‐like structure, composing of needle‐like building blocks. After calcinations at 800°C, it converts to cubic γ‐Al2O3 with hierarchical structure retained by a topotactical process. N2 adsorption and desorption reveal that the obtained γ‐Al2O3 has a BET surface area of 101 m2/g with a narrow mesoporous size of about 13 nm and a broad macroporous‐size distributions of 200–500 nm, respectively. The as‐generated γ‐Al2O3 with hierarchical structure shows good capacities for removing Congo red from wastewater, indicating that 3D hierarchical structure has excellent adsorption ability.

Platelike a-Al 2 O 3 powder was obtained at 850°C by thermal decomposition of ammonium aluminum carbonate hydroxide precursor, which was treated by hydrofluoric acid. The results showed the decomposition of the as-prepared precursors experienced via three steps, adsorption of physical water, dehydration of crystalline water, and decomposition of the precursor, and the activation energies of the above three steps were calculated using the Coats-Redfern method. Meanwhile, the intermediate of (NH 4 ) 3 AlF 6 obtained played an important role in decreasing activation energy of the decomposition and phase transformation. Moreover, the thermal conductivity of the epoxy resin filled with platelike alumina was improved obviously.R. Hill-contributing editor Manuscript No. 33972.

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