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Montevideo, Uruguay

Vieitez I.,Laboratorio Of Grasas Y Aceites | Pardo M.J.,Laboratorio Of Grasas Y Aceites | Da Silva C.,URI Integrated Regional University Brazil | Da Silva C.,State University of Maringa | And 6 more authors.
Journal of Supercritical Fluids | Year: 2011

The transesterification of castor oil under supercritical ethanol using a catalyst-free continuous process was investigated. The effect of water concentration on the reaction medium, reaction temperature, pressure, and substrates flow rate were studied. A maximum ester content of 74.2% was achieved when the reactor was operated at 573 K, 20 MPa, substrates flow rate of 0.8 ml min-1, and 5 wt% water concentration in the alcohol. The ester content of the product increased with the operation temperature, but after certain temperature level the converse effect was observed. This adverse effect was attributed to oil degradation, which increased to 88.7% at 648 K (at the flow rate of 0.8 ml min-1). A favorable effect on ester content was observed when the water concentration was increased, unlike the effect of water on the conventional alkali-catalyzed process. © 2010 Elsevier B.V. Source


Vieitez I.,Laboratorio Of Grasas Y Aceites | Da Silva C.,URI Integrated Regional University Brazil | Da Silva C.,State University of Maringa | Alckmin I.,URI Integrated Regional University Brazil | And 5 more authors.
Journal of Supercritical Fluids | Year: 2011

It is well known that during the supercritical alcoholysis of vegetable oils the main transesterification reaction occurs simultaneously to several decomposition phenomena, In order to separately study the effect of such phenomena, pure ethyl esters from soybean oil (SBOEE) were mixed with ethanol at a molar ratio 40:3 (ethanol:SBOEE) and exposed for different periods to supercritical conditions in a continuous system, at 20 MPa and different temperatures from 250 to 375 °C. It was experimentally observed that the ester content of the processed samples were lower than that corresponding to the original SBOEE, indicating the occurrence of decomposition processes, which were more important as the temperature increased and the flow rate diminished. The content of polyunsaturated esters of the treated SBOEE was lower than that of the starting mixture, showing that the decomposition rate was highly dependent on the nature and instauration degree of the alkyl chain. © 2010 Elsevier B.V. Source


Vieitez I.,Laboratorio Of Grasas Y Aceites | da Silva C.,URI Integrated Regional University Brazil | Alckmin I.,URI Integrated Regional University Brazil | Borges G.R.,URI Integrated Regional University Brazil | And 4 more authors.
Renewable Energy | Year: 2010

This work investigates and compares the reaction performance of soybean oil transesterification under supercritical methanol and ethanol, in a continuous catalyst-free process, as a cleaner alternative to conventional chemically catalyzed process. Reactions were performed in a tubular reactor, at 20 MPa, with oil to alcohol ratio of 1:40, varying the temperature in the range from 250 °C to 350 °C, and at two levels of water concentrations, 0 and 10 wt%. Although both processes proceeded with a relatively high reaction rate, conversion achieved by methanolysis was higher than that obtained by ethanolysis. Water positively affected both process: higher ester content and triacylglycerols depletion occurred when 10 wt% water was used compared with anhydrous conditions. Temperature increase favored the conversion of soybean oil to the corresponding methyl or ethyl esters, although temperatures above 300 °C increased the fatty acid degradation degree, a phenomenon responsible for the low ester contents obtained at the highest temperatures and lowest flow rates studied. © 2010 Elsevier Ltd. All rights reserved. Source

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