Microwave-assisted furfural production from xylose and bamboo hemicellulose in a biphasic medium

Exploring environmental-friendly routine for efficient furfural production from lignocellulosic biomass is meaningful. Here, bamboo hemicellulose (BH) and xylose were used to produce furfural under microwave irradiation in a biphasic medium, in which 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4) served as the reaction phase and catalyst, whereas 1,4-dioxane served as the extraction phase. The effects of retention time, temperature, [Bmim]HSO4 dosage, and water addition on the furfural yield were evaluated. Results showed the highest total furfural yields of xylose and BH could reach 55.65 mol% and 68.37 mol%, respectively, which were further enhanced to 63.87 mol% and 85.69 mol%, respectively, by adding a small amount of water. The kinetic analysis showed the dehydration rate constant of the formed xylose from BH to furfural was almost twice that of directly using xylose as substrate. Compared with the hydrolysis of BH to xylose, the dehydration of xylose to furfural required higher activation energy. The activation energy of consuming furfural to form by-products was higher than 73 kJ/mol. The recycled [Bmim]HSO4 performed great reusability, and a small amount of ethanol residue could enhance the total furfural yields of xylose and BH, up to 73.48 mol% and 88.28 mol%, respectively.