Preparation and Physisorption Characterization of <scp>d</scp>-Glucose-Templated Mesoporous Silica Sol−Gel Materials

Abstract

The synthesis of mesoporous silica materials has been achieved with d-glucose as a nonsurfactant pore-forming agent in the sol−gel reactions of tetraethyl orthosilicate under basic or near neutral (pH 6) conditions. Regardless of the pH values of the medium, transparent and monolithic glucose-containing silica gels could be obtained. d-Glucose was removed by water extraction to afford silica materials with high specific surface area of ∼800 m2/g, pore volume of ∼0.5 cm3/g, and narrow pore distribution with BJH pore diameter of 3.2−3.5 nm, indicative of the mesoporosity. As the glucose concentration is increased in the synthesis, these pore parameters generally increase, and the N2 sorption isotherms gradually transform from reversible type I to type IV-like isotherms with H2 hysteresis. At low glucose concentrations (<36 wt %), both micropores and mesopores contribute to the porosity of the materials. However, at high glucose concentrations (36−64 wt %), mesopores are dominant. The characteristics of pore structures are similar to those for the materials obtained under acid catalysis. The aggregation or assembly of the aggregates of the glucose molecules and their hydrogen-bonding interactions with the silicate species might direct the mesophase formation.