Transesterification of soybean oil with methanol was investigated. Three stepwise and reversible reacttons are believed to occur. The effect of variations in mixing intensity (Reynolds number = 3,100 to 12,400) and temperature (30 to 70'CJ on the rate oireaction were studied while the molar ratio of alcohol to triglycerol (6:l) and the concentration of catalyst (0.20 wt% based on soybean oil) were held constant. The variations in mixing intensity appear to effect the reaction parallel to the variations in temperature. A reaction mechanism consisting of an initial mass transfer-controlled region followed by a kinetically controlled region is proposed. The experimental data for the latter region appear to be a good fit into a second-order kinetic mechanism. The reaction rate constants and the activation energies were determined for all the forward and reverse reactions. lAOCS 74,1457-1463 (1997).KEY WORDS: Biodiesel, kinetics, methyl esters, mixing, renewable fuels, soybean oil, transesterification. triglycerides.Over the last few years. fatty acid methyl esters have assumed importance as research has intensified on the utilization of vegetable oils and animal fats derivatives for liquid fuels, known as biodiesel. Fatty acid methyl esters are products of the transesterification of fats and oils with alcohols in the presence of an acid or an alkaline catalyst. Three consecutive and reversible reactions are believed to occur ( l ) . Mono-(MG) and diglycerides (DG) are the intermediates formed in these reactions.The variables affecting the transesterification process (also called alcoholysis) have been intensively investigated as widening industrial uses were found for esters (2-6). Molar ratio of alcohol to vegetable oil, type of catalyst, temperature, and presence of impurities such as free fatty acids and moisture are among the variables that have been studied.There are a number of kinetic studies in the literature on the transesterification of esters with alcohol. However, only a few of these studies deal with vegetable oils and fatty esters. The studies on the transesterification kinetics for nonfatty esters include: the determination of the reaction rate constants, the equilibrium constant, and the activation energy for the acid-catalyzed reaction of butanol with ethyl acetate (7) and ethanol with butyl acetate (8). .4 review by Sridharan and Mathai (9) on the transesterification reactions involving alco--To whom correspondence should be addressed. E-&. houreddini@unI.edu.holysis, acidolysis, vinyl interchange, and ester-ester inrerchange contains many of the reported studies.The transesterification kinetics for vegetable oils and fatty esters has been reported in a few studies. Dufek and coworkers (10) studied the acid-catalyzed esterification and transesterification of 9(1O)-carboxystearic acid and its mono-and dimethyl esters and reported unequal chemical reactivity for different carboxyl and carboxymethyl groups. Freedman and conorkers ( l ) investigated both acid-and alkaline-catalyzed transester...
Data for viscosity as a function of temperature from 24 Please refer to the preceding paper in this issue (3) for to llO°C (75 to 230°F) have been measured for a number the fatty acid composition and source or manufacturer of vegetable oils (crambe, rapeseed, corn, soybean, milk-of each vegetable oil, and for the purity and the manufacweed, coconut, lesquerella) and eight fatty acids in the turers of the fatty acids used in the experimental prorange from Cg to CZZ The viscosity measurements were cedures. The information was provided by the performed according to ASTM test methods D 445 and manufacturers.
Increased environmental awareness and depletion of resources are driving to develop alternative fuel from renewable resources that are environmentally more acceptable. Esters of fatty acids (biodiesel, derived from the transesterification vegetable oils, have properties similar to components of peh-oleior. based diesel fuel Cost has been a major factor slowing the commercialization of biodiesel Glycerol is the coproduct of the esterification process. In this work the feasibility of the glycerol of vegetable oil. with crude glycerol derived from the transesterification of the vegetable oils and animal fats was studied. Utilization of the crude co-product of the biodiesel process was investigated for improving the overall economy The transesterification of soybean oil for fuel purpose was optimized. Optimization results are presented. transesterification of beef tallow produces a mixture of esters which is more concentrated in the saturated fatty acids. Physical properties of these esters are similar to esters of soybean oil. Reaction results and properties for beef tallow are presented.
Complete data for density as a function of temperature have been measured for a number of vegetable oils (crambe, rapeseed, corn, soybean, milkweed, coconut, lesquerella), as well as eight fatty acids in the range C9 to C22 at temperatures from above their melting points to 110°C (230°F). The specific gravity and density measurements were performed according to American Society for Testing and Materials (ASTM) standard test methods D 368, D 891 and D 1298 for hydrometers and a modified ASTM D 369 and D 891 for pycnometers. Correlation constants, based on the experimental data, are presented for calculating the density of fatty acids and vegetable oils in the range of temperature from 24°C (75°F) or the melting point of the substance, to 110°C (230°F). The constants are valuable for designing or evaluating such chemical process equipment as heat exchangers, reactors, process piping and storage tanks. Estimated density of fatty acids by a modified Rackett equation is also presented.
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