Preparation of mesoporous silica materials with non-surfactant hydroxy-carboxylic acid compounds as templates via sol-gel process

Mesoporous silica materials with pore sizes of 2-6 nm have been prepared th rough the sol-gel reactions of tetraethyl orthosilicate (TEOS) in the prese nce of hydroxy-carboxylic acid compounds, including citric acid (CA), malic acid (MA), tartaric acid (TA) and lactic acid (LA), as templates or pore-f orming agents, followed by extraction with ethanol to remove the template m olecules. The materials are characterized by infrared spectroscopy, nitroge n adsorption-desorption tests, powder X-ray diffraction (XRD) and transmiss ion electron microscopy (TEM). The results indicate that the materials prep ared at template concentrations of 40-60 wt% have large surface areas (ca. 900 m(2)/g) and pore volumes (ca. 1.0 cm(3)/g). The mesoporosity arises fro m interconnecting channels and pores with, however, disordered channel arra ngements. The pore diameters and pore volumes increase as the template conc entration is increased. The mesoporous materials retain high surface areas and pore volumes with a little change in pore diameters upon calcination at 773 K for 6 h. (C) 2001 Elsevier Science B.V. All rights reserved.