Preparation, characterization and catalytic activity towards green reactions of sulfonic functionalized SBA-15

• Autores: Basaldella, Elena Isabel; Legnoverde, María Soledad; Jiménez-Morales, Ignacio; Rodríguez-Castellón, Enrique; Dalla Costa, Bruno O.; Querini, Carlos A.
• Año de publicación: 2011
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ingeniería; Química; Mesoporous silica; SBA-15; Functionalization; Sulfonation; Acid catalysts; Alkylation; Esterification
• Institución: Universidad Nacional de La Plata

Acidic heterogeneous catalysts based on the anchorage of sulfonic groups on SBA-15 mesoporous silica were synthesized. In a first synthesis step, samples containing mercapto groups were prepared by co-condensation of tetraethylorthosilicate with 3-mercaptopropyltrimethoxysilane, in presence of ethylene-propylene block copolymer as mesoporous silica structure director. In other samples, mercapto groups were introduced by post-functionalization of the traditional calcined SBA-15. In a second step, these mercapto groups were oxidized in order to get sulfonic acid groups on the surface. Characterization of the samples was carried out by N2 adsorption-desorption, FTIR, XPS and acid-base titration. Spectroscopic techniques showed that the effective incorporation of sulfonic groups depends on the synthesis methodology used. In turn, the SBA-15 post-synthesis functionalization produces changes in structural characteristics like a decrease in BET surface and changes in the pore size distribution. The as-prepared materials were tested as acid catalysts in the alkylation of isobutane with 1-butene, and in the esterification of free fatty acids with methanol. The results obtained show a lack of activity in the alkylation reaction which can be associated with the formation and stabilization of the intermediate carbocation species.
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