A comparative study of ethanol production using dilute acid, ionic liquid and AFEX™ pretreated corn stover
- Michigan State Univ., East Lansing, MI (United States). Dept. of Chemical Engineering and Materials Science. Dept. of Energy (DOE) Great Lakes Bioenergy Research Center (GLBRC)
- Michigan State Univ., East Lansing, MI (United States). Dept. of Chemical Engineering and Materials Science. Dept. of Energy (DOE) Great Lakes Bioenergy Research Center (GLBRC); Univ. of Wisconsin, Madison, WI (United States). Dept. of Biochemistry. Dept. of Energy (DOE) Great Lakes Bioenergy Research Center (GLBRC)
- Jilin TuoPai Agriculture Products Development Ltd, Jilin (China)
- Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States). Deconstruction Division; Sandia National Lab. (SNL-CA), Livermore, CA (United States). Biological and Material Science Center
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center (BESC); Univ. of California, Riverside, CA (United States). Dept. of Chemical and Environmental Engineering. Bourns College of Engineering. Center for Environmental Research and Technology (CE-CERT)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center (BESC); Univ. of California, Riverside, CA (United States). Center for Environmental Research and Technology (CE-CERT). Bourns College of Engineering
In a biorefinery producing cellulosic biofuels, biomass pretreatment will significantly influence the efficacy of enzymatic hydrolysis and microbial fermentation. Comparison of different biomass pretreatment techniques by studying the impact of pretreatment on downstream operations at industrially relevant conditions and performing comprehensive mass balances will help focus attention on necessary process improvements, and thereby help reduce the cost of biofuel production. An on-going collaboration between the three US Department of Energy (DOE) funded bioenergy research centers (Great Lakes Bioenergy Research Center (GLBRC), Joint BioEnergy Institute (JBEI) and BioEnergy Science Center (BESC)) has given us a unique opportunity to compare the performance of three pretreatment processes, notably dilute acid (DA), ionic liquid (IL) and ammonia fiber expansion (AFEXTM), using the same source of corn stover. Separate hydrolysis and fermentation (SHF) was carried out using various combinations of commercially available enzymes and engineered yeast (Saccharomyces cerevisiae 424A) strain. The optimal commercial enzyme combination (Ctec2: Htec2: Multifect Pectinase, percentage total protein loading basis) was evaluated for each pretreatment with a microplate-based assay using milled pretreated solids at 0.2% glucan loading and 15 mg total protein loading/g of glucan. The best enzyme combinations were 67:33:0 for DA, 39:33:28 for IL and 67:17:17 for AFEX. The amounts of sugar (kg) (glucose: xylose: total gluco- and xylo-oligomers) per 100 kg of untreated corn stover produced after 72 hours of 6% glucan loading enzymatic hydrolysis were: DA (25:2:2), IL (31:15:2) and AFEX (26:13:7). Additionally, the amounts of ethanol (kg) produced per 100 kg of untreated corn stover and the respective ethanol metabolic yield (%) achieved with exogenous nutrient supplemented fermentations were: DA (14.0, 92.0%), IL (21.2, 93.0%) and AFEX (20.5, 95.0%), respectively. The reason for lower ethanol yield for DA is because most of the xylose produced during the pretreatment was removed and not converted to ethanol during fermentation. Compositional analysis of the pretreated biomass solids showed no significant change in composition for AFEX treated corn stover, while about 85% of hemicellulose was solubilized after DA pretreatment, and about 90% of lignin was removed after IL pretreatment. As expected, the optimal commercial enzyme combination was different for the solids prepared by different pretreatment technologies. Due to loss of nutrients during the pretreatment and washing steps, DA and IL pretreated hydrolysates required exogenous nutrient supplementation to ferment glucose and xylose efficiently, while AFEX pretreated hydrolysate did not require nutrient supplementation.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- AC02-05CH11231; FC02-07ER64494
- OSTI ID:
- 1511397
- Journal Information:
- Biotechnology for Biofuels, Vol. 7; ISSN 1754-6834
- Publisher:
- BioMed CentralCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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