Monday, April 30, 2007

Kinetics parameters of castor oil and soybean oil

Nvea De lima da silva, Cesar Benedito Batistella, Maria Regina Wolf Maciel, and Rubens Maciel Filho. School of Chemical Engineering, State University of Campinas, Albert Einstein, So Paulo, AA 13081970, Brazil

This work presents a kinetic study, carried out in a lab pilot plant, for the transesterification of soybean oil and castor oil, with ethanol in presence of sodium hydroxide as catalyst. The apparatus used for the experiment was a 1-L jacketed reactor, equipped with a variable speed agitator. The temperature of the reactor was controlled and maintained at 20, 30, 40, 55 and 80 °C. The reaction time was 30 minutes and samples were collected and analyzed in an HPSEC (High performance size-exclusion chromatography). The impact of the rotational speed was investigated and the value of 400 rpm showed to be appropriated. During the basic transesterification, all temperatures studied leading to a conversion of oil to biodiesel of about 100%.

The excess of ethanol was recovered under vacuum at approximately 80°C in a rotational evaporator and the mixture was left to settle in two layers. The upper oil layer was the biodiesel (later neutralized with sulfuric acid and dried with sodium sulfate) and the lower layer was glycerol, catalyst and some impurities.

This work presents the transesterification process of castor oil with ethanol in the presence of sodium hydroxide as catalyst, because it leads to better conversion and smaller reaction time. A large scale process based on this study is proposed a using the UniSim simulator.