Novel one-pot dry method for large-scale production of nano γ-Al₂O₃ from gibbsite under dry conditions

Abstract

An unprecedented facile one-pot dry method using commercial gibbsite in the presence of ammonium bicarbonate is introduced for the large-scale production of nanostructured gamma alumina particles (NGAs). The efficacy of different non-toxic chelating agents was studied through a dry process in an autoclave reactor, set at a low pressure (60 psi) and temperature (85 °C), and calcination at 450–550 °C was obtained γ-Al₂O₃. The synthesized physical NGAs were characterized using a variety of techniques, such as X-ray diffraction, field-emission scanning electron microscopy energy-dispersive X-ray, N₂ adsorption/desorption, fourier transform infrared spectroscopy, and thermogravimetric/differential thermal analyzer. The Brunauer-Emmet-Teller surface area, pore volume, and average pore size were determined as 360 m² g⁻¹, 0.5 cm³ g⁻¹, and 7 nm, respectively, under optimum conditions. Importantly, it was shown that the dry method is well suited for the synthesis of NGAs in the presence of ammonium bicarbonate. Particles were further tuned by controlling reaction temperature, the concentration of the chelating agents, and calcination time. These results demonstrate that a dry method strategy using inexpensive gibbsite and precursors for synthesis of NGAs, instead of aluminum alkoxides, make these materials ideal candidates for numerous applications, including heterogeneous catalysis and adsorbents.

Graphical abstract