Biodiesel production through ionic liquid catalysed esterification

• Autor(a) principal: Tadevosyan, Arevik
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10198/14667
• topic: Biodiesel; Esterification; Ionic Liquids; Recovery; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Química

Biodiesel is an alternative fuel diesel that can be produced from vegetable oils and animal fats. There is a recent growing interest in the development of alternative technologies to the oil economy, based on renewable energy sources. A possible solution is a biofuel usable in compression-ignition engines, produced from biomass rich in fats and oils. A wide range of raw materials can be used in the production of biodiesel. Nevertheless, the use of sources that do not compete with the food market like waste cooking oils, which usually feature high levels of free fatty acids (FFA’s), can put problems in the process of production of biodiesel through alkaline transesterification. These problems are partially overcome by the use of catalysts, such as ionic liquids (IL’s) that also promote reactions of esterification of FFA’s to biodiesel. Thus, the objective of this work consists in the study of the influence of IL's application in the catalysis of: esterification reactions of organic acids to the corresponding methyl esters. In the first part of the work the influence, as catalysts, of several ionic liquids in the esterification reaction of oleic acid was analyzed. The experimental conditions were as follows: reaction time 6 hours, oleic acid / methanol molar ratio = 1/10 and temperature 90 ° C. The ionic liquids evaluated were as follows: 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO4]), 1-butyl-3-methylimidazolium methanesulfonate ([BMIM][CH3SO3]), 1-butyl-3-methylimidazolium methylsulfate ([BMIM][CH3SO4]), 1-metylimidazolium hydrogen sulfate ([MIM][HSO4]) and tributylmethylammonium methylsulfate. The values obtained for the conversion of the oleic acid esterification reaction showed that the ionic liquid [BMIM] [HSO4] would be one of the most promising catalysts. In a second part of the work, the recovery of LI [BMIM] [HSO4] was studied and several esterification reactions of oleic acid were carried out using a quantity of catalyst of 10 wt%, 15 wt% and 20 wt% relative to the mass of oleic acid. The experimental conditions were as follows: reaction time 6 hours, oleic acid / methanol molar ratio = 1/10 and temperature 90 ° C. The reaction yield was found to be 76.6% to 10% IL, 83.3% to 15% IL and 84.8% to 20% IL. These yields decreased to 58.2% (10% IL) with 4 cycles of recycling, 75.2% (15% IL) with 5 cycles of recycling and 77.1% (20% IL) with 5 cycles of recycling. The results obtained confirm that it is possible to reuse this IL in successive reactions of esterification without great loss of yield and with this to significantly reduce the costs associated with the purchase of these compounds that are quite expensive.