Prepararion of Highly Active Esterification Catalyst SBA-15 Mesoporous Silica Functionalized with Sulfonic Acid Group

Well-ordered, mesoporous, hybrid SBA-15 materials containing alkyl(methyl) and sulfonic acid group were prepared by post and direct-synthesis methods in the presence of triblock copolymer P123 as the structure-directing agent under acid conditions. The materials have been characterized by powder X-ray diffraction, nitrigon gas sorption(BET), FTIR, themogravimetric weight loss(TGA) and solid state 29Si MAS NMR. XRD result shows the two kinds of catalysts have the SBA-15 structure characters (hexagonal, p6mm). FTIR and 29Si-MAS-NMR results show the surface of SBA-15 functionalized by the organic-silica group and the acid site is B acid site. BET shows them has a large surface area and large pore size. TGA shows they have a higher thermal stability than sulfonic acid resin. They are efficient catalysts for the esterification of methanol with oleic acid. The d-SBA-15-SO3H catalyst has a higher hydrothermal stability and hydrophobicity than p-SBA-15-SO3H. The d-SBA-15-SO3H can be reused many times, and the activity can retain stable. The direct synthesis method is more simple, convenient and efficient comparison with the post synthesis method.