(693e) Glycerol-Free Biodiesel Production from Palm Oil and Supercritical Dimethyl/Diethyl Carbonate Mixtures with Trace Heterogeneous Base Catalyst

Palm oil, the representative component of waste fried oil, was used to produce glycerol-free biodiesel under supercritical dimethyl/diethyl carbonate (DMC/DEC) conditions at the catalysis of trace amount of heterogeneous potassium hydroxide (KOH). The single factor experimental design and Box-Behnken response surface methodology were combined to investigate the optimal reaction conditions and the interactive effects of variables. As a result, an optimal biodiesel yield of 91.3% (molar ratio of FAMEs/FAEEs=1.5:1) was obtained under milder reaction conditions: Reaction time is 34.7min, reaction temperature is 309.3^oC, reaction pressure is 12MPa, molar ratio of DMC/DEC to oil is 26.9:1, molar ratio of DMC/DEC is 1:1 and catalyst amount of 0.2wt% (based on oil). Finally, the fuel properties of biodiesel were tested and compared with ASTM standard D-6751, and the cold flow performance of biodiesel had reached the requirements of commercial 0# diesel in China, with a cold filter plugging point of 3^oC and a solidifying point of -2^oC, respectively. Moreover, the differential scanning calorimetry (DSC) and rheological results showed that the low temperature property of biodiesel has been improved due to the excessive generation of ethyl esters during the supercritical method.