A new processing route for cleaner production of biodiesel fuel using a choline chloride based deep eutectic solvent

摘要

In this study, the free fatty acids (FFA) content in acidic crude palm oil (ACPO) was converted to fatty acid methyl esters (FAME) using a choline chloride based deep eutectic solvent (ChCl-DES) for the first time. This DES is composed of a mixture of a hydrogen bond donor (i.e. p-toluenesulfonic acid monohydrate) and a salt (i.e. choline chloride). The pre-treatment esterification stage involved the use of ChCl-DES. A dosage of 0.75 mass ratio of ChCl-DES to ACPO resulted in reducing the FFA of ACPO from 9.00% to less than 1%. The molar ratio of methanol to oil was 10:1 (methanol to oil), at a temperature of 60 C and within 30 min reaction time. Three recycling runs of ChCl-DES were achieved without significant loss in its activity. The yield of the final product after the alkaline transesterification was 92 wt% with 0.07% FFA and FAME content 96 mol%. All other properties have met the international standard specifications for biodiesel quality. The ChCl-DES can be used as a pre-treatment catalyst for a wide range of waste and acidic oils.