Valorization of waste cooking oils through conversion processes into biodiesel catalyzed by [HMIM][HSO4]

• Autor(a) principal: Monteiro, Fábio
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10198/24724
• topic: Waste cooking oils; Esterification; Response Surface Methodology (RSM); Ionic liquids; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia do Ambiente

Biodiesel is a renewable alternative to fossil diesel, produced from vegetable oils, animal fats and residual oils. In the present work, the influence of the application of the ionic liquid 1-methylimidazolium hydrogen sulfate [HMIM]HSO4 in the catalysis of transesterification/esterification reactions in a simulated acidic oil, obtained through the incorporation of oleic acid in a waste cooking oil, was studied at 65 °C. The effect of the selected parameters: reaction time (2 h, 4 h and 8 h), catalyst dosage (5 % wt, 10 % wt and 15 % wt), molar ratio oil: methanol (1:5, 1:15 and 1:20) and mass percentage of incorporation of oleic acid (20%, 40% and 60%) was studied using a Response Surface Methodology (RSM) from an experimental design based on a Box-Behnken 34. Three responses were evaluated: the conversion in terms of reduction of the acidity of the simulated oil (R1), the Fatty Acid Methyl Esters (FAME) mass content of the biodiesel produced (R2) and the yield in terms of mass of FAME obtained at the end of reaction in relation to the initial mass of the simulated oil (R3). In the analysis of the experimental results obtained, it is concluded that for all responses, the least relevant factor is the catalyst dosage, while the other factors are significant for the model. The most favorable reaction conditions for the conversion response in terms of acidity reduction correspond to a reaction time of 6 h, catalyst dosage of 5% wt, molar ratio oil/methanol 1:20, incorporation of 20% oleic acid, temperature of 65 ºC, with an average conversion of 76.70%. The most favorable reaction conditions for the FAME content and yield response are similar, corresponding to a reaction time of 6h, catalyst dosage 5% wt, oil/methanol molar ratio of 1:20, incorporation of 60% oleic acid and temperature of 65 ºC, with an average conversion of 42.52% and 37.70%, respectively. Additionally, the recovery and reuse of the ionic liquid was studied in two reaction cycles, at the optimum conditions corresponding to FAME content and Yield, already mentioned. The reaction conversion in terms of acidity reduction, FAME content and Yield remained practically constant during the two cycles. In terms of acidity reduction, it was obtained for the first cycle, 69.81% and for the second cycle, 69.39%. FAME content of 42.44% was obtained for the first cycle and 42.60% for the second cycle. Finally, the yield in the first cycle was 35.91% and for the second, a value of 39.50% was obtained. The achieved results indicate that, for the selected operational conditions, IL promotes only the esterification reaction. Thus, the possibility of using this IL to treat oils with high acidity values is viable, and subsequently a transesterification reaction with basic catalysts can be carried out.