Ordered mesoporous molecular sieves synthesized by a liquid-crystal template mechanism

MICROPOROUS and mesoporous inorganic solids (with pore diameters of ≤20 Å and ∼20–500 Å respectively) 1 have found great utility as catalysts and sorption media because of their large internal surface area. Typical microporous materials are the crystalline framework solids, such as zeolites 2 , but the largest pore dimensions found so far are ∼10–12 Å for some metallophosphates 3–5 and ∼14 Å for the mineral cacoxenite 6 . Examples of mesoporous solids include silicas 7 and modified layered materials 8–11 , but these are invariably amorphous or paracrystalline, with pores that are irregularly spaced and broadly distributed in size 8,12 . Pore size can be controlled by intercalation of layered silicates with a surfactant species 9,13 , but the final product retains, in part, the layered nature of the precursor material. Here we report the synthesis of mesoporous solids from the calcination of aluminosilicate gels in the presence of surfactants. The material 14,15 possesses regular arrays of uniform channels, the dimensions of which can be tailored (in the range 16 Å to 100 Å or more) through the choice of surfactant, auxiliary chemicals and reaction conditions. We propose that the formation of these materials takes place by means of a liquid-crystal 'templating' mechanism, in which the silicate material forms inorganic walls between ordered surfactant micelles.