High temperature dilute phosphoric acid pretreatment of corn stover for furfural and ethanol production

Furfural was produced from corn stover by one stage pretreatment process using dilute H3PO4 and solid residues following furfural production were used for ethanol production by Saccharomyces cerevisiae NRRL-Y2034. A series of experiments were conducted at varied temperatures (140-200 °C) and acid doses (0.0-2.0%, v/v) in order to determine optimal conditions. The effects of time (5-25 min) and substrate concentration (5-15%, w/w) on furfural production were determined at optimal temperature (200 °C) and acid dose (0.75%, v/v). Maximum furfural yield (10.8 ± 0.3 g/100 g stover) was achieved at 20-25 min duration with 5% (w/w) corn stover which corresponds to 61.6% of the potential yield. About 74% of the glucan content of corn stover was converted to glucose after enzymatic digestion of solid residues. S. cerevisiae NRRL-Y2034 fermented glucose from the solid residues efficiently to ethanol. It produced 0.47-0.50 g ethanol per g glucose which corresponds to 92-99% of the theoretical yield.