1. Field of the Invention
This invention relates to the field of mesoporous silicas. More particularly, it relates to mesoporous silicas having three-dimensional channel systems.
2. Background of the Art
Mesoporous materials have been known to researchers for many years, and are used for a variety of applications. In general these materials are inorganic solid materials characterized by a porous structure which is formed by channels or pores, frequently having average diameters in a general range of from 2 to 50 nanometers (nm). The pores may be uniform with constant pore diameters, or non-uniform with a variety of pore diameters. The porous structure provides for a large internal surface area with adsorptive capacity for molecular species which are capable of entering the pores. The pores may be three-dimensional, penetrating essentially the entire volume of the solid material.
Mesoporous materials may be amorphous or crystalline. Examples of mesoporous materials include synthetic or natural crystalline pure silicates or aluminosilicates. Such may also be referred to as framework aluminosilicates where the framework is based on a three-dimensional network of [(Al,Si)4] tetrahedra which are linked to each other, at the corners, by shared oxygen atoms.
However, despite successful application of such mesoporous, or potentially mesoporous, silica materials in certain applications, some of these materials suffer from less than desirable properties or capabilities including, but not limited to, dispersion in a given desired medium, diffusion or selectivity in separations operations, and/or contact with adsorbates and/or reactants, and/or from other difficulties in their use in specific industrial streams. In view of the above it is desirable to develop new means of modifying silica-based mesoporous materials to reduce or eliminate one or more of these problems or limitations.