Understanding the role of tetramethyl urea for the synthesis of mesoporous alumina

Mesoporous alumina was synthesized by hydrothermal method at 150 °C for 6–24 h using tetramethyl urea followed by their calcination at 500–1100 °C. The samples were characterized by XRD, FTIR, N2 adsorption–desorption, FESEM and TEM. The γ-Al2O3 was found to be stable up to 1000 °C for the samples prepared at 150 °C/6 h, and up to 900 °C for the samples prepared at 150 °C/12–24 h. The BET surface area values of 500 °C treated samples were 428 m2 g−1, 393 m2 g−1, and 366 m2 g−1 for the reaction time of 6 h, 12 h and 24 h, respectively. FESEM and TEM showed the formation of alumina nanoparticles at 150 °C/6 h, which ripened to flake-shaped alumina comprising of alumina nanoflakes (70–100 nm) at 150 °C/12–24 h. To understand the role of tetramethyl urea, a tentative formation mechanism was illustrated.