Mesoporous M41S systems

Since the first synthesis of mesoporous M41S alumosilicates in 1992 [1,2] numerous systems of mesoporous materials have been reported. The principle method of these syntheses consists of the utilisation of lyotropic liquid crystals as supramolecular templates, which act as structure directing agents in order to mesostructure inorganic building units. 

Tanev et al. have reported the synthesis of mesoporous materials via a route which involves self-assembly between neutral primary amines and neutral inorganic framework precursors.12 The regularity of the pore structure in these materials has been illustrated by lattice images which show a honeycomb like structure. The system of channels of these molecular sieves produces solids with very high internal surface area and pore volume. This fact combined with the possibility of generating active sites within the channels produces a very unique type of acid catalyst. In the case of transition metal substituted M41S, the principal interest lies in their potential as oxidation catalysts, especially Ti and V substituted MCM and HMS type materials, and more recently synthesised large pore materials.13... 

Silica supports in HPLC have mesopores and macropores. The presence of micropores leads to slow desorption kinetics and a lower loading capacity than found in supports with mesopores. The pore system can be built up by a unidimensional, two-dimensional, and network system of interconnected and intersecting pores, respectively MCM-41, as a member of the family of M41S materials, for instance, exhibits a unidimensional pore system of hexagonally arranged channels with a pore diameter ranging from 2 to 6 nm (Fig. 1) [10]. As the pore walls of MCM-41 are made of amorphous silica, the material is not considered to be a crystalline solid in its strict physical meaning but is rather termed an ordered mesoporous silica [11]. 

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