| The synthesis of oleic acid isobutyl ester by the esterification of oleic acid and isobutanol with n-butyl triethylamine hydrogen sulfate ionic liquid as catalyst and the low temperature fluidity of biodiesel blended with oleic acid isobutyl ester were studied. The results of single factor experiment showed that the conversion rate was the highest under esterification conditions of reaction time 45 min, reaction temperature 110℃, catalyst dosage 6% (based on the dosage of oleic acid) and molar ratio of isobutanol to oleic acid 5∶1; the range analysis result of orthogonal experiment indicated that the effect of reaction temperature on conversion rate was the greatest, followed by catalyst dosage, reaction time and molar ratio of isobutanol to oleic acid; the optimal reaction conditions were obtained as follows: reaction temperature 100℃, catalyst dosage 6%, reaction time 45 min and molar ratio of isobutanol to oleic acid 5∶.The verification test was conducted under the optimal conditions, and the conversion rate was up to 98.6%. The freezing point, cold filter plugging point and kinematic viscosity of oleic acid isobutyl ester obtained were -25.3, -21.5℃ and 6.52 mm2/s respectively, which had good low temperature performance and poor fluidity. Both the low temperature performance of biodiesel and fluidity of oleic acid isobutyl ester improved when oleic acid isobutyl ester was blended with biodiesel. |
