Mesoporous silicates and method of making same

Abstract

A method of preparing mesoporous silica from a reaction mixture comprising a mineral acid such as HCl, an inorganic oxide source such as tetraethoxysilane, a surfactant such as cetyltrimethlyammonium bromide and water. The reaction mixture is mixed, e.g., by stirring or sonication, until sufficiently polymerized that mesostructured silica may be formed by a subsequent heating step, as indicated by the reaction mixture becoming opaque. This mixing is typically performed at room temperature for about 30-70 minutes. Then, the reaction mixture is heated in a pressurized vessel at a time, temperature and pressure sufficient to form mesostructured silica, e.g., at 60 to 230° C. for 15 to 80 minutes. Finally, mesoporous silica is recovered by filtering, drying and calcining in a furnace having a temperature in the range of 400 to 600° C. in air for at least 6 hours. Mesoporous silica made in accordance with present invention has pores with a narrow diameter distribution (23-24 Å), but with highly disordered placement relative to one another. As a result, the mesoporous silica is characterized by powder X-ray diffraction pattern having no discernible peaks or one unusually broad peak with very low intensity. Furthermore, a large percentage of the mesoporous silica particles are spherical, i.e., more than 50% and typically in excess of 80%.

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