Co-production of xylose, lignin, and ethanol from eucalyptus through a choline chloride-formic acid pretreatment

[Display omitted] •A choline chloride-formic acid (ChCl-FA) pretreatment were developed in this work.•Pretreatment can significantly improve the hydrolysis and fermentation of eucalyptus.•The maximal ethanol yield 16.5 g/100 g feedstock, corresponding 74.5% theoretical yield.•A certain amount of xylose (61.4%) and lignin (80.7%) also can be obtained in this work. A choline chloride-formic acid (ChCl-FA) pretreatment followed by enzymatic hydrolysis and fermentation were developed in this work for co-produce bioethanol, xylose, and lignin from eucalyptus. Results showed that ChCl-FA pretreatment can simultaneously degrade the xylan (∼95.2%) and lignin (∼74.4%) in eucalyptus, and obtained the pretreated eucalyptus having high glucan content and a numbers of cracks and holes, which was conducive to follow-up cellulase attacking. The hydrolysis experiments showed the maximum yield of glucose of 100 g eucalyptus was 35.3 g, which was equivalent to 90.3% of glucan in eucalyptus feedstock. The fermentation of enzymatic hydrolysate finally achieved the ethanol yield of 16.5 g, which corresponded to 74.5% theoretical ethanol yield from initial glucan in eucalyptus. In addition, 12.1 g xylose and 23.9 g lignin also could be obtained in pretreated liquid or/and hydrolysis residue, which represented for 61.4% xylan and 80.7% lignin in eucalyptus feedstock, respectively.