p-Toluenesulfonic Acid-based Deep Eutectic Solvent as Transesterification Catalyst for Biodiesel Production.

In this study, acidic deep eutectic solvents (DESs) have been studied as catalyst in transesterification of soybean oil with methanol to produce biodiesel. p-Toluenesulfonic acid-based deep eutectic solvent (P-DES), composed of p-toluenesulfonic acid and choline chloride (1:3, mol/mol), was found to be an efficient transesterification catalyst for biodiesel production. The optimum conditions for the transesterification process were as follows: 8% P-DES catalyst, 8:1 molar ratio of methanol to oil, reaction temperature of 110°C and 2 h reaction time. The transesterification yield could reach 98.66±0.17%. And the P-DES exhibited as a heterogeneous catalyst after the reaction, which could be separated easily. And P-DES could remove the trace amount of by-product (glycerol) in the final biodiesel product, making this process more simple and cleaner.