Ethanol and furfural production from corn stover using hybrid fractionation process with zinc chloride and simultaneous saccharification and fermentation (SSF)

Abstract

Two-stage hybrid fractionation process was investigated to produce cellulosic ethanol and furfural from corn stover. Zinc chloride (ZnCl 2) was used to selectively solubilize hemicellulose in the first stage. During the second stage, the remaining treated solids were converted into ethanol using commercial cellulase and Saccharomyces cerevisiae or recombinant Escherichia coli, KO11. Hybrid fractionation process recovered >90% of glucan, -90% of xylan, and -75% of lignin at optimal reaction conditions: 1 st stage: 5% acidified ZnCl 2, 7.5 ml/min, 150 °C (10 min) and 170 °C (10 min); 2 nd stage: Simultaneous saccharification and fermentation (SSF). Furfural yield from hemicellulose hydrolysates was 58 %. SSF of ZnCl 2 treated solid with Saccharomyces cerevisiae resulted in 69-98 % of theoretical maximum ethanol yields based on glucan present in the treated solids. After fermentation, solid residues contained mostly lignin. Based on total lignin in untreated corn stover, the lignin recovery yield was -75%.