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Face of the global energy shortage and environmental pollution of these two great challenges, countries around the world have begun to research and development of biomass energy sources to replace or reduce the consumption of non-renewable energy sources. Biodiesel is in this context, with its light pollution low emissions, good performance and renewable and other superior characteristics have attracted much attention, so the development of bio-diesel industry is significant. The traditional production of biodiesel use more base-catalyzed transesterification method, but there is the product difficult to recycle, waste lye pollute the environment, raw water, acid demand is high, higher costs and other shortcomings. Supercritical transesterification biodiesel is a new method, its greatest feature is the raw material in the water and free fatty acid content is almost no effect on the reaction, without a catalyst, and the reaction speed, time is short. Compared with the chemical method, separation and purification is simple, environmentally friendly and therefore received extensive attention. Although biodiesel has great development prospects, but in the industrial-scale production and use subject to many factors, the most important is the high cost of raw materials, so in order to reduce the cost of biodiesel, taking full advantage of the supercritical state transesterification advantages, we study to Mao rice bran oil as raw material, the use of supercritical methanol transesterification process of biodiesel by response surface analysis and optimization of a catalyst without catalytic supercritical reaction conditions, the optimum process conditions. First to twelve methyl as internal standard for the determination of fatty acid methyl esters in biodiesel content of the main gas chromatographic analysis, the optimum operating conditions for the column temperature was 220 ℃, injector temperature 250 ℃, detector temperature 250 ℃ The carrier gas was high purity N 2 , flow rate 2 mL / min, injection 1μL, split ratio 1:10. Its wide linear range, high accuracy and good reproducibility. Under the conditions of the supercritical methanol biodiesel transesterification studied. Response surface analysis method under the experimental conditions were optimized optimal reaction conditions: molar ratio of 25.1, the reaction temperature 295.9 ℃, reaction time 40.5 min, the maximum yield of 79.8% at this time. By the regression analysis, the reaction temperature and reaction time on the yield greater impact. Finally, the reaction system was added sodium methoxide as catalyst, a base catalyst hair bran investigated with supercritical methanol transesterification. Optimum reaction conditions 31.2 molar ratio, reaction temperature 275 ℃, reaction time 31.4 min, 0.14% catalyst, by the analysis results, the raw rice bran oil is relatively high acid value, a base catalyst is added and the yield was not increased.
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