Conversion of xylose and xylan into furfural in biorenewable choline chloride–oxalic acid deep eutectic solvent with the addition of metal chloride

An environmentally benign processing approach for furfural production from xylose and xylan under very mild conditions (353–373 K) was developed with the addition of metal chlorides in ChCl–oxalic acid (a deep eutectic solvent (DES)) synthesized from cheap and renewable starting materials). ChCl–oxalic acid acted as both a Brønsted acid catalyst and a reaction medium in this catalytic route. In addition, a biphasic system with methyl isobutyl ketone as an extracting reagent (DES/MIBK) to further increase furfural yield was also proposed. This processing approach for producing furfural eliminated the large energy consumption for high pressure saturated steam and the generation of acidic effluent, which was very difficult to handle. The whole catalytic system was more environmentally friendly compared with the commercial process for furfural production.

Both monophasic (DES) and biphasic (DES/MIBK) routes for processing xylose/xylan to deliver furfural were developed in the presence of trivalent metal chlorides in ChCl/oxalic acid (a deep eutectic solvent synthesized using cheap and renewable building blocks). The concept offered a more ecologically benign approach than the current industrial furfural production processes.Figure optionsDownload as PowerPoint slide