Homogeneous borotungstic acid and heterogeneous micellar borotungstic acid catalysts for biodiesel production by esterification of free fatty acid

摘要

A highly negatively charged borotungstic acid H_5BW_(12)O_(40) had been tested as homogeneous catalyst in esterification. Compared with common used H_3PW_(12)O_(40), it displayed a higher conversion (98.7%) and excellent efficiency (96.2%) due to its high amount of protons in methanol. In order to overcome the drawbacks of homogeneous heteropolyacid H_5BW_(12)O_(40), a Bronsted-surfactant-combined (C_(16)TA)H_4BW_(12)O_(40) (C_(16)TA = cetyltrimethyl ammonium) had been fabricated with strong acidity and nano-size micellar structure resulting in enhanced activity and stability during the reaction, which exhibited consistent activity during recycling in esterification reaction.