A previously described synthetic method was modified to improve the porosity of the alumina product. The compound (Et2AlNH2)3 was prepared from ammonia and triethylaluminum (Et3Al) in toluene solvent. Addition of acetone to form a solution of ethylaluminoxane (EtAlO) and acetonine (2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine) was followed by addition of two equivalents of water to give an alumina precursor. Alumina precursors also were prepared by the direct hydrolysis of (Et2AlNH2)3. Powder X-ray diffraction, 27Al MAS NMR, and N2 adsorption/desorption isotherms were used to analyze the aluminas after calcination of the precipitates. The aluminas exhibited high pore volume and surface area, and they were amorphous after calcination at 500 °C. One alumina showed a significant fraction of pentacoordinate aluminum after heating to 300 °C in air or 500 °C in steam atmosphere. The products crystallized as α-Al2O3 at the low temperature of 1000 °C, which reduces their applicability for catalysts. Synthesis variables and their effects on alumina properties are discussed.

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