Synthesis of Meso/Macroporous γ‐Alumina via Aluminum Pellet with Controllable Porosity: Ammonium Bicarbonate Influences through Drying and Calcination Steps

Abstract Mesoporous and macroporous γ‐alumina have been synthesized using the economic source of aluminum pellets. To manipulate the porosity and overall porous characteristics, ammonium bicarbonate was incorporated into the gel and studied to determine its influence on the porous structure of the obtained γ‐alumina. The nanostructure of the synthesized γ‐alumina, characterized by the N 2 sorption isotherms and FESEM analysis, indicated that the γ‐alumina of desired pore size distribution could be achieved using such economical source of aluminum when ammonium bicarbonate was considered to tailor its porous structure. The formation of macropores in synthesized γ‐alumina was confirmed by the FESEM images and the crystalline structure of the γ‐alumina of optimal porous structure was revealed via X‐ray diffraction pattern. Before and after being calcinated at 500 °C, TG‐DTA and FT‐IR analyses were also conducted to better assess the impact that thermal processes could have on ultimate γ‐alumina porous characteristics. Considering the embedded ammonium bicarbonate expander, a two‐step mechanism was finally proposed to explain the observed porosity developed through heating stages. Different porosity patterns developed through drying and calcination steps were then contributed to the reactions taking place at each, and N 2 sorption isotherms, as well as the FESEM images, were used to evaluate the introduced pore forming mechanisms.