High titer ethanol production from poplar by aluminum chloride catalyzed organosolv pretreatment and simultaneous saccharification and fermentation

Abstract

In this study, AlCl3-catalyzed organosolv pretreatment with different temperatures were put forward to destroy the recalcitrant structure of poplar by degrading lignin and hemicellulose, reserve the majority of cellulose, and improve the ethanol conversion in subsequent simultaneous saccharification and fermentation (SSF). With the increment of pretreatment temperature from 150 °C to 200 °C, the ethanol concentration with 12% solid loading was increased gradually from 5.51 to 39.80 g/L. This enhancement was ascribed to the structure alteration, which was verified by X-ray diffraction (XRD), Fourier transform-infrared spectrum (FT-IR), Thermogravimetric (TG), scanning electron microscope (SEM), and Brunner-Emmet-Teller (BET). Furthermore, the batch and fed-batch SSF with high solid loading were compared. When the solid loading was less than 20%, batch SSF liberated higher ethanol concentration of 59.76 g/L with ethanol yield of 69.57%. As the solid loading was higher than 24%, fed-batch SSF presented superior performance in liberating ethanol.