With the aim of developing a process of biodiesel production that is environmentally benign much interest has been focused on the use of solid base catalysts, such as calcium oxide, for the transesterification of vegetable oils with methanol. In the study reported herein a recycling reactor was used in bench scale, with the capacity to produce 3 L of biodiesel. The reactor was designed especially for this research study. A full 2 3 factorial plan was used to evaluate the process parameters related to this study, in particular, the catalyst concentration, the alcohol to oil molar ratio and the reaction time. Using this equipment for the transesterification reaction resulted in the recovery of the excess alcohol. The reaction products were characterized using gas chromatography and liquid analysis to determine the ester and calcium concentrations, respectively. The main conclusions drawn were that the best conversion percentage (100% of biodiesel) was reached when the methanol:oil molar ratio was 6:1, the reaction time was 75 min and the catalyst mass was 3% in relation to the oil mass used in this process. The CaO concentration determined exceeded the limit of concentration defined by legislation and thus a secondary operation was carried out to purify the reaction products obtained. The results of this study showed a high performance, and the proposed experiment could be used as a new and innovative way to produce biodiesel in the future.

No abstract

This study reports the synthesis and characterization of a Ni/Zn layered double hydroxide salt intercalated with acetate ions and the subsequent replacement of the acetate ions with molybdate ions via an ion exchange reaction, conducted at two different pH values. Regardless of the pH employed during the synthesis, the basal spacing in the Ni/Zn layered double hydroxide salt decreased from 13.08 Å to approximately 9.5 Å, which agreed with intercalation of hydrated molybdate anions. The non-calcined material and the material submitted to heat treatment at 250 °C (basal spacing reduced to 7.35 Å, due to dehydration) were tested as catalyst for the methyl transesterification of soybean oil. Like sodium molybdate in homogeneous media, the solid materials were active catalysts. After reaction at 120 °C for 4 h, the materials afforded high conversions at an alcohol/soybean oil molar ratio of 35:1 and preserved the structure after three consecutive uses.In conclusion, intercalation of molybdate anion into the layered double hydroxide salt proved to be an efficient alternative to support the active species and transform a soluble catalyst into a solid with application in heterogeneous catalysis.

Este é um artigo de acesso aberto distribuído sob os termos da Licença de Atribuição Creative Commons ExpErimEntação no Ensino dE Química

RESUMO -Com a demanda crescente de energia, vê-se a necessidade de buscar novas metodologias eficientes e mais sustentáveis para atendê-las. O presente artigo tem como objetivo avaliar os catalisadores: hidroxiacetato de zinco/cobalto, zinco/níquel e de zinco/cobre (HAZCo, HAZNi e HAZCu) em reações de transesterificação em meio heterogêneo para produção de biodiesel. Esses catalisadores são compostos lamelares da classe dos Hidroxissais Duplos Lamelares (HSDL). Estes, foram sintetizados seguindo metodologia óxido sal e caracterizados mediante Difração de Raios X (DRX) e Espectroscopia Vibracional na Região do Infravermelho (FTIR). Os catalisadores foram testados em reações de transesterificação metílica com óleo de soja em diferentes condições operacionais antes e após tratamento térmico a 250 °C. Os resultados obtidos foram quantificados pelo rendimento massa/massa, sendo os melhores resultados presentes nos catalisadores submetidos ao tratamento térmico com rendimentos acima de 80%.