Direct synthesis of large mesopore aluminosilicates templated by lyotropic liquid crystals

A family of aluminosilicates with large uniform mesopores and high specific surface areas is described in which the pore size may be adjusted in the range 3–7 nm by controlled hydrothermal treatment. This has the effect of swelling the liquid crystal arrangement and leads to increased pore volume, surface area and pore diameter. Aluminosilicates with Si/Al ratios between 10 and 80 are directly synthesised using tetraethoxysilane and aluminium nitrate by direct liquid crystal templating using the triblock copolymer, Pluronic P123. 27Al MAS NMR spectra show that the majority of the aluminium is tetrahedrally coordinated, and that hydrothermal treatment favours incorporation of aluminium into the silica. The number of surface acid sites determined by adsorption of ammonia at 100 °C increases non-linearly with the Si/Al ratio.