| Object: This paper focused on the synthesis process of biodiesel from cottonseed oil, and experiments on the biodiesel production catalyzed by chemical and lipase were performed. Obtained the optimized condition through investigate of reaction conditions on the transesterification of fatty acid methyl ester yield. Physical and chemical characteristics of a self-made biodiesel were analyzed. Carry on the experiment of enlarging of 5L, offer the feasible basis for the fact that the industrialization of biodiesel will be realized in the future.Methods: Cottonseed oil biodiesel is produced through chemical and enzymatic catalysis methods. Optimizing the reaction conditions by multi-level and single-factor and orthogonal experiments. Qualitative and quantitative analysis of biodiesel were followed by HPLC chromatography and Thin-layer chromatography. Determine physical and chemical characteristics of cottonseed oil biodiesel with density, viscosity sport, flash point, acid number and pour point.Results:1. Producing cottonseed oil biodiesel by chemical catalyzed methods. Through single-factor and orthogonal analysis,the optimum conditions are obtained as follows: reaction temperature is 40℃, molar ratio of methanol to oil is 5:1, amount of KOH is 1.1% and reaction time is 60 min. Under these conditions, the yield of biodiesel is 98.43%.2. Under the condition of dimethyl carbonate as acyl acceptor, the effect of substrate ratio, reaction temperature, reaction time, stirring speed, amount of water added and t-butanol, amount of enzyme, etc. on the yield of fatty acid methyl ester were studied by single factor method in single batch experiments. The optimal conditions were dimethyl carbonate/oil molar ratio 4:1, reaction temperature 50℃, t-butonal as organic solvent, V(t-butanol):V(dimethyl carbonate)=1.5, stirring speed 160r/min, 12.5%Novozym435 which based on oil weight, no water added, after 24 hours, under these conditions.The value of fatty acid methyl ester yield is 96.81±0.65%.3. Under the condition of methyl acetate as acyl acceptor, the effect of substrate ratio, reaction temperature, reaction time, amount of water added and amount of enzyme, etc. on the yield of fatty acid methyl ester were studied by single factor method in single batch experiments. The optimal conditions were methyl acetate/oil molar ratio 14:1, reaction temperature 40℃, stirring speed 160r/min, 25%Novozym435 which based on oil weight, no water added, after 18 hours, under these conditions.The value of fatty acid methyl ester yield is 92.67±1.04%.4. Under the optimized conditions, using dimethyl carbonate as the acyl acceptor, the Novozym435 relative activity was remain at about 90% after 22batch reactions(528 h); Using methyl acetate as the acyl acceptor, the Novozym435 relative activity was also remain at about 90% after 30 batch reactions(540 h).5. Determination of the main physical and chemical properties of biodiesel: density (20℃) 0.888g/cm3, viscosity sport(20℃)7.184mm~2/s, viscosity sport(40℃)4.125mm~2/s, flash point174℃, pour point -2℃, acid number 0.23.Conclusion:1. Cottonseed oil biodiesel is produced through chemical and enzymatic catalysis methods. Qualitative and quantitative analysis of biodiesel were followed by HPLC chromatography and Thin-layer chromatography.2. Obtained the optimized reaction conditions through multi-level and single-factor experiments and orthogonal experiments.3. Determined physical and chemical characteristics of cottonseed oil biodiesel with density, viscosity sport, flash point, acid number and pour point. In addition to the pour point was little higher compared with standard, and other measured characteristics of the basic standards in line with Germany DIN EN 51606 standard.4. Carry on the enlarging experiment in a 5L reactor, the process of enlarging experiment was good; provide a basic date for the biodiesel industrial production in the future. |
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