title: Bioconversion of hybrid poplar to ethanol and co-products using an organosolv fractionation process: optimization of process yields.
abstract: An organosolv process involving extraction with hot aqueous ethanol has been evaluated for bioconversion of hybrid poplar to ethanol. The process resulted in fractionation of poplar chips into a cellulose-rich solids fraction, an ethanol organosolv lignin (EOL) fraction, and a water-soluble fraction containing hemicellulosic sugars, sugar breakdown products, degraded lignin, and other components. The influence of four independent process variables (temperature, time, catalyst dose, and ethanol concentration) on product yields was analyzed over a broad range using a small composite design and response surface methodology. Center point conditions for the composite design (180 degrees C, 60 min, 1.25% H(2)SO(4), and 60% ethanol), yielded a solids fraction containing approximately 88% of the cellulose present in the untreated poplar. Approximately 82% of the total cellulose in the untreated poplar was recovered as monomeric glucose after hydrolysis of the solids fraction for 24 h using a low enzyme loading (20 filter paper units of cellulase/g cellulose); approximately 85% was recovered after 48 h hydrolysis. Total recovery of xylose (soluble and insoluble) was equivalent to approximately 72% of the xylose present in untreated wood. Approximately 74% of the lignin in untreated wood was recovered as EOL. Other cooking conditions resulted in either similar or inferior product yields although the distribution of components between the various fractions differed markedly. Data analysis generated regression models that describe process responses for any combination of the four variables.
authors.affiliation: Department of Wood Science, University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada V6T 1Z4. xuepan@forestry.ubc.ca
authors.forename: Xuejun
authors.initials: X
authors.lastname: Pan
authors.forename: Neil
authors.initials: N
authors.lastname: Gilkes
authors.forename: John
authors.initials: J
authors.lastname: Kadla
authors.forename: Kendall
authors.initials: K
authors.lastname: Pye
authors.forename: Shiro
authors.initials: S
authors.lastname: Saka
authors.forename: David
authors.initials: D
authors.lastname: Gregg
authors.forename: Katsunobu
authors.initials: K
authors.lastname: Ehara
authors.forename: Dan
authors.initials: D
authors.lastname: Xie
authors.forename: Dexter
authors.initials: D
authors.lastname: Lam
authors.forename: Jack
authors.initials: J
authors.lastname: Saddler
mesh_terms: D001673:Biodegradation, Environmental; D005591:Chemical Fractionation / Q000379:methods*; D020650:Combinatorial Chemistry Techniques / Q000379:methods*; D000431:Ethanol / Q000737:chemistry* / Q000302:isolation & purification*; D009930:Organic Chemicals / Q000737:chemistry; D032107:Populus / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D014934:Wood
chemical_list: D009930:Organic Chemicals; D012997:Solvents; D000431:Ethanol