Transesterification reactions over morphology controlled amino-functionalized SBA-15 catalysts

The amino-functionalized SBA-15 (NH2-SBA-15) catalysts have been synthesized by different approaches such as direct co-condensation, prehydrolysis of sodium metasilicate, and post synthetic-grafting methods in order to get different morphologies by using the amphiphilic triblock copolymer, pluronic P123 as a surfactant and 3-aminopropyltriethoxysilane (APTES) as a precursor of functional groups under a strong acidic condition. The functionalized materials were confirmed with X-ray diffraction (XRD), N-2 gas adsorption/desorption studies, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the amount of amino-groups was evaluated by TGA analyses. Catalytic transesterification reactions of diethylmalonate with various aliphatic and aromatic alcohols were investigated over the amino-functionalized SBA-15 catalysts. Among the functionalized catalysts, the material synthesized via direct co-condensation method which had short channeled hexagonal platelet morphology exhibited enhanced catalytic activities with normal aliphatic alcohols than other fibrous type catalysts. The activities of the catalysts were found to be very much dependent on morphologies, dispersion of amino groups and molecular shape of alcohols. (c) 2007 Elsevier B.V. All rights reserved.