Hydrolysis of rapeseed oil to fatty acids using pyrrolidonium ionic liquids as catalysts

ABSTRACT

This study aimed to evaluate the hydrolysis of rapeseed oil using pyrrolidonium ionic liquids as catalysts under atmospheric pressure. The process parameters were optimized using a sequence of experimental protocols to evaluate the effects of ionic liquid loading, dosage of emulsifier, weight ratios of substrates, temperature and time. The results demonstrated that the ranking of catalytic activity of ionic liquids is N-methyl-2-pyrrolidonium hydrogen sulfate salt ([H_NMP]HSO₄)>1-(3-sulfonic acid) propyl-2-pyrrolidonium hydrogen sulfate salt ([C₃SO₃Hnhp]HSO₄)>2-pyrrolidonium hydrogen sulfate salt ([Hnhp]HSO₄). In a batch reactor, the hydrolysis reaction conditions in the presence of [H_NMP]HSO₄ were investigated and optimized as follows: catalyst loading of 20% (based on the weight of oil), oil/water weight ratio of 1:2, emulsifier loading dosage of 4 wt % (based on the weight of oil), hydrolysis temperature of 100°C, and hydrolysis time of 30 h. The catalytic performance of this ionic liquid remained excellent even after reuse five times.

KEYWORDS:

• Ionic liquids
• hydrolysis
• catalyst
• rapeseed oil
• fatty acids

Acknowledgments

This work was supported by the National Natural Science Foundation of China (51366015), the Yunnan Provincial Sciences and Technology Platform Promotion Plan (2013DH041), the Specialized Research Fund for Doctoral Programs of Universities (20135303110001), the Yunnan Province Key Fund of Applied Basic Research (2014FA030), and the Open Fund from Yunnan Key Laboratory of Rural Energy Engineering (2017KF03).