Synthesis and characterization of a hexagonal mesoporous silica with enhanced thermal and hydrothermal stabilities

A synthetic route was developed for a novel hexagonal mesoporous silica that has remarkably wide channel diameters and thick walls. The procedure involved the acid-catalyzed hydrolysis of tetraethylorthosilicate in a water/ethanol/isopropoanol solvent mixture while employing 1-hexadecylamine as a templating agent and mesitylene as an auxiliary agent. After removal of the template by either extraction with ethanolic hydrochloric acid or by calcination at 550 degrees C, the resulting mesoporous materials had surface areas of 1283 and 1211 m(2)/g. The channel diameters were found to be 47.2-51.1 angstrom, while the wall thicknesses were 20.9-21.1 angstrom. X-ray powder diffraction demonstrated that the novel mesoporous silica belonged to the MCM-41 structural family. Notably, they displayed higher thermal and hydrothermal stabilities, and have higher surface areas than conventionally prepared MCM-41 silica. The thickest channel walls (21.1 angstrom) can withstand calcination to nearly 850 degrees C with minimal structural damage. The calcined sample was more resistant to hydrothermal treatment in boiling water than was the solvent-extracted product but both materials showed minimal change after 25 h of hydrothermal treatment. (C) 2010 Elsevier B. V. All rights reserved.