Preparation and Characterization of Cyano―functionalized Mesoporous Silica

Cyano―functionalized mesoporous silicas were synthesized by one―pot co―condensation of tetraethoxysilane (TEOS) and 2―cyanoethyltriethoxysilane (CTES), using Pluronic P123 triblock copolymer as the structure― directing agent under strongly acidic conditions. The physicochemical properties, such as structure, morphology, pore property and cyano content were characterized by XRD, SEM, N2 adsorption―desorption isotherm, FT―IR and elemental analysis, respectively. It was found that the order for adding the two silicon sources, namely CTES and TEOS has a profound influence on the content and distribution of cyano group. Within three mixture orders, the sample synthesized with pre―mixed TEOS and CTES as silica sources is best, with highest cyano content and uniform distribution. As cyano content increasing, surface morphology and pore properties are changed. The straight cylindrical pore structure is transformed into bottle―neck―like structure with up to 20mol% CTES loading in the synthesis mixture. Pore volume, surface area and pore size decrease from 0.70 cm3/g to 0.22 cm3/g, 666 m2/g to 312 m2/g, 4.2 nm to 2.7 nm, respectively when cyano content is increased, which maybe result from that cyano group occupies part of pore channel.