Effect of NaOH-catalyzed organosolv pretreatment on the co-production of ethanol and xylose from poplar

Abstract

NaOH-catalyzed organosolv pretreatment was proposed to degrade lignin, retain cellulose and hemicellulose in poplar, and the pretreated substrates was used to produce ethanol and xylose simultaneously. After the organosolv pretreatment conducted at 205 ºC for 20 min with 1.2% NaOH, the optimal ethanol concentration and xylose yield reached 30.1 g/L and 10.3 g/100 g raw material after 48 h, respectively, and the xylose yield was positively correlated with the ethanol concentration (R2 =0.934). The alteration in chemical composition and structure enhanced the ethanol concentration and xylose yield, which was revealed by Scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform-infrared spectrum (FT-IR), Thermogravimetric (TG), and correlation analysis. In addition, their capacity for generating ethanol and xylose during three fermentation processes was comprehensively compared. The results indicated that SSF was beneficial to improve ethanol concentration, and SHF was in favour of enhancing xylose and ethanol yields to 95.4% and 85.3% based on retained xylan after pretreatment and the fermentable glucose, respectively. The NaOH enhanced organosolv pretreatment exhibited excellent performance in converting poplar into energy and chemicals, which presented a new idea for biomass refining.