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Aluminum-substituted mesoporous SBA-15 (Al−SBA-15) materials were directly synthesized by a hydrolysis-controlled approach in which the hydrolysis of the silicon precursor (tetraethyl orthosilicate, TEOS) is accelerated by fluoride or by using tetramethyl orthosilicate (TMOS) as silicon precursor rather than TEOS. These materials were characterized by powder X-ray diffraction (XRD), N2 sorption isotherms, TEM, 27Al MAS NMR, IR spectra of pyridine adsorption, and NH3-TPD. It is found that the matched hydrolysis and condensation rates of silicon and aluminum precursors are important factors to achieve highly ordered mesoporous materials. 27Al MAS NMR spectra of Al−SBA-15 show that all aluminum species were incorporated into the silica framework for the samples prepared with the addition of fluoride. A two-step approach (sol−gel reaction at low pH followed by crystallization at high pH) was also employed for the synthesis of Al−SBA-15. Studies show that the two-step approach could efficiently avoid the leaching of aluminum from the framework of the material. The calcined Al−SBA-15 materials show highly ordered hexagonal mesostructure and have both Brönsted and Lewis acid sites with medium acidity.

Periodic mesoporous organosilicas (PMOs), one of most advanced organic-inorganic hybrid materials, have attracted much research attention because of their combined advantages of ordered mesoporous structure and fusion of organic and inorganic fragments within the pore wall. PMOs with diverse mesostructures, morphologies and compositions have emerged in the past few years, and shown unprecedented properties. Recent years have seen the great progress in the controlled synthesis of functionalized PMOs towards specific application demands, particularly in catalysis. This Feature Article describes selected examples of the synthesis of functionalized PMOs for catalytic applications in the past few years.