Preparation of Glycerol Carbonate Esters by using Hybrid Nafion-Silica Catalyst
Glycerol carbonate esters (GCEs), which are valuable biomass-deriv. compds., have been prepd. through the direct esterification of glycerol carbonate and long org. acids with different chain lengths, in the absence of solvent, and with heterogeneous catalysts, including acidic-org. resins, zeolites,...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2013 |
| País: | España |
| Institución: | Universitat Politècnica de València (UPV) |
| Repositorio: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| Idioma: | inglés |
| OAI Identifier: | oai:riunet.upv.es:10251/40395 |
| Acceso en línea: | https://riunet.upv.es/handle/10251/40395 |
| Access Level: | acceso abierto |
| Palabra clave: | Biomass Carboxylic acids Esterification Heterogeneous catalysts Solid-state structures QUIMICA ORGANICA |
| Sumario: | Glycerol carbonate esters (GCEs), which are valuable biomass-deriv. compds., have been prepd. through the direct esterification of glycerol carbonate and long org. acids with different chain lengths, in the absence of solvent, and with heterogeneous catalysts, including acidic-org. resins, zeolites, and hybrid org.-inorg. acids. The best results, in terms of activity and selectivity towards GCEs, were obtained using a Nafion-silica composite. A full reaction scheme has been established, and it has been demonstrated that an undesired competing reaction results in the generation of glycerol and esters derived from a secondary hydrolysis of the endocyclic ester group, which is attributed to water formed during the esterification reaction. The influence of temp., substrate ratio, catalyst-to-substrate ratio, and the use of solvent has been studied and, under optimized reaction conditions and with the adequate catalyst, it was possible to achieve 95 % selectivity for the desired product at 98 % conversion. It was demonstrated that the reaction rate decreased as the no. of carbon atoms in the linear alkyl chain of the carboxylic acid increased for both p-toluenesulfonic acid and Nafion-silica nanocomposite (Nafion SAC-13) catalysts. After fitting the exptl. data to a mechanistically based kinetic model, the reaction kinetic parameters for Nafion SAC-13 catalysis were detd. and compared for reactions involving different carboxylic acids. A kinetic study showed that the reduced reactivity of carboxylic acids with increasing chain lengths could be explained by inductive as well as steric effects. |
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