Cleaner synthesis of mesoporous alumina from sodium aluminate solution

Mesoporous alumina (MA) has attracted much attention because of its potential industrial applications as catalyst and adsorbent. The synthesis of MA is performed commonly from organic aluminium alkoxide in non-aqueous media such as alcohol, although this process is more expensive than its inorganic synthesis. However, to date, MA inorganic synthesis processes have been environmentally unfriendly and generate large masses of worthless salt by-product. A cleaner process for the synthesis of MA from supersaturated sodium aluminate solution by the neutralization of sodium bicarbonate, using Cetyltrimethyl Ammonium Bromide (CTAB) as a template, is proposed in this research. The sodium carbonate by-product from this process can be readily recycled by carbonation with carbon dioxide to prepare the sodium bicarbonate reagent solution. This novel process can be integrated into the commonly and widely used sintering process in the alumina industry, i.e., part of the sodium carbonate by-product can be used to extract alumina from bauxite to make sodium alumina solution through sintering. The prepared MA was characterized as hydrothermally stable and short-range ordered mesoporous gamma-alumina with controllable pore size and qualified modality. The cleaner and economical synthesis of MA from inorganic sources can significantly promote its application in industry.