LAUSR

An efficient process for furfural production from xylan using acidic deep eutectic solvents (DES), acting both as solvents and catalysts, is here disclosed. DES composed of cholinium chloride ([Ch]Cl) and malic acid or glycolic acid at different molar ratios, and the effects of water and γ-valerolactone (GLV) contents, solid/liquid (S/L) ratio and microwave heating were investigated. The best furfural yields were obtained with the DES [Ch]Cl:Malic Acid (mole ratio 1:3) + 5 wt.% of water, under microwave heating for 2.5 min of reaction time, at 150 °C, at a S/L ratio of 0.050, and GLV at a weight ratio of 2:1. Under these conditions, a remarkable furfural yield (75%) was achieved. Direct distillation of furfural from the DES-GLV solvent and distillation from 2-methyl-tetrahydrofuran (2-Me-THF) after a back-extraction step were studied for furfural recovery, achieving 89% of furfural recovery from 2-Me-THF. This strategy allows the DES-GLV recycling, for at least three times, with no significant furfural yield losses (> 69%). This is the fastest and highest yield process reported up to date for furfural production, using bio-based DES as solvents and catalysts, paving the way for the process scale-up.