Response surface methodology was used for optimizing the extraction process of Xanthoceras sorbifolia Bunge seeds oil.Based on single factor experiments,the mathematical model was arranged according to Box-Behnken central composite design.The optimum extraction process was investigated by response surface methodology with extraction temperature,extraction time,liquid-material ratio as influencing factors,the extraction rate of Xanthoceras sorbifolia Bunge seeds oil as index. The optimum extraction conditions were as follows:extraction temperature was 58 ℃,extraction time was 31 min,liquid-material ratio was 6∶1(mL∶g).Under above conditions,the average extraction rate was 59.58%,which was in good agreement with the predicted counterpart.

The preparation of biological diesel oil from Xanthoceras sorbifolia seed by transesterification in supercritical methanol with catalyst of ionic liquid HSO4 was discussed in this paper.The variables affecting the fatty acid methyl ester yield during the transesterification reaction,such as the ratio of methanol oil to Xanthoceras sorbifolia Bunge oil,the reaction temperature,the reaction time,the reaction pressure,the catalyst content and recycle of catalyst were investigated.The experimental results showed that yield of 92.33% was achieved when the reaction was performed with 42∶1 of the ratio of methanol to Xanthoceras sorbifolia Bunge oil and HSO4 content of 0.5wt% at 300 ℃ for 11 MPa and 25 min.The catalyst can be used repeatedly.