The Open Catalysis Journal

2012, 5 : 66-71
Published online 2012 November 02. DOI: 10.2174/1876214X01205010066
Publisher ID: TOCATJ-5-66

On Three-Fold Coordinated Si Sites in Mesoporous MCM-41 Catalysts

J. Aguilar-Pliego , P. Bosch , C. Zicovich-Wilson , G. Herrera-Perez and V. H. Lara
Universidad Autonoma Metropolitana-Azcapotzalco, San Pablo 180, 02200, D.F., Mexico.

ABSTRACT

29Si-NMR, gas adsorption and SAXS results are discussed to determine if the geometry and the electronic properties of Si sites, present in the MCM-41walls, are more similar to three- than to four-fold coordinated sites. The features of Si-MCM-41, SBA-15, Y zeolite and silica (SiO2), characterized by several techniques, are compared. It is shown that the pre-polymer geometries are similar to those of the zeolite secondary building units, but, in the organization-polymerization step, the generation of partially saturated or quite stressed structures is favored.

Keywords:

MCM-41, porous materials, fractal.