Lime pretreatment of pelleted corn stover boosts ethanol titers and yields without water washing or detoxifying pretreated biomass

Abstract

Large-scale industrial cellulosic ethanol production is significantly restricted by the high costs of lignocellulosic biomass handling, transportation and storage. Therefore, biomass densification is thought to be necessary to solve these logistical problems. Nevertheless, because of its high density, densified biomass may have an impact on subsequent biomass processing. In this study, lime pretreatment was investigated on pelleted corn stover (PCS) for ethanol production. The glucan and xylan conversions of lime-PCS exceeded 90% via enzymatic hydrolysis after optimization of pretreatment conditions. Corn stover was characterized using the flourier transform infrared spectrum (FT-IR) and scanning electron microscopy (SEM), which revealed that after lime pretreatment, the acetyl groups in biomass were removed and cell wall decomposition products redeposited on outer cell wall surfaces. Finally, without washing or detoxifying pretreated biomass, enzymatic hydrolysis and fermentation resulted in a high ethanol titer (65.1 g/L). The results indicated that lime pretreatment is efficient in pretreating PCS.