Synthesis strategies leading to pure alumina mesophases in aqueous solution

While the synthesis and characterization of the now well known mesoporous silicas or aluminosilicates of the MCM-41, MCM-48 and MCM-50 families is now being widely documented, very few studies on the existence and stabilization of the all-alumina analogs have been reported so far. In aqueous solution, only lamellar, thermally unstable mesophases could be obtained from Al 3+ and anionic surfactants like alkylsulphonates or phosphates [1] or sodium dodecyl sulphate (SDS) [2, 3]. In non aqueous media, either lamellar [4] or pseudo hexagonal [5] alumina mesophases were prepared by reacting Al alkoxides with non ionic polyglycols and various carboxylic acids respectively. In the latter case, the calcined solids involve randomly ordered pores and a specific surface area between 400 and 700 m 2 /g. Stein and Holland [6] reported the aqueous synthesis of mesoporous aluminas in the presence of Al polycations and SDS but the surface area of the calcined materials was only 18 m 2 /g.