Catalytic effect of acidic deep eutectic solvents for the conversion of levulinic acid to ethyl levulinate

The production of ethyl levulinate has been investigated by levulinic acid esterification with ethanol in the presence of deep eutectic solvents. Deep eutectic solvents are environmentally friendly materials that can be easily synthesized by mixing hydrogen bond donor and acceptor. In this study, six different choline chloride based deep eutectic solvents were synthesized. Due to the requirement of esterification reaction, carboxylic acids were selected as hydrogen bond donor to gain acidic nature. Reactions were carried out in a batch reactor at various operating conditions. The most catalytically active catalyst was found to be DES formed by choline chloride and para-toluene sulfonic acid. The maximum conversion of levulinic acid was achieved as 99.8% at 353 K for 1 h in the presence of 5 wt% of catalyst. The highest selectivity of ethyl levulinate was achieved as 99.9% at 353 K, catalyst loading of 5 wt% and ethanol/ levulinic acid molar ratio of 1. (C) 2020 Elsevier Ltd. All rights reserved.