Efficient furfural production from bamboo via the pretreatment in acidic glycerol/choline chloride DES followed by in-situ hemicellulose degradation

An acidic DES consisting of glycerol, choline chloride and p-toluenesulfonic acid (TA) was employed for bamboo pretreatment, enabling efficient removal of hemicellulose (97.02%) and lignin (85.13%) while retaining 82.66% of cellulose under mild conditions (100 °C, 2 h, 40 mmol TA). After lignin separation, the hemicellulose-derived sugars in the DES solution were subsequently converted in situ to furfural with a desirable yield of 86.86% (140 °C, 2 h), and kinetic analysis revealed a low activation energy of 20.93 kJ/mol for the furfural formation. A small amount of water (3%) was introduced into the spent DES, which disrupts the original rigid hydrogen bond network of the DES through the interaction with glycerol hydroxyl groups. The weakening of hydrogen bond strength may promote the release of acidic proton of TA, further facilitating the acid-catalyzed dehydration of xylose to furfural. On the other hand, the viscosity of DES was largely reduced with the introduction of water, which probably improved the mass transfer of furfural to MIBK, enabling the desirable furfural yield from the in-situ conversion of hemicellulose-derived sugars in DES system. This study presents a facile strategy for the in-situ conversion of hemicellulose to furfural, avoiding the cumbersome separation of hemicellulose-derived carbohydrates from DES system.