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Title: Impacts of Deacetylation Prior to Dilute Acid Pretreatment on the Bioethanol Process

Abstract

Dilute acid pretreatment is a promising pretreatment technology for the biochemical production of ethanol from lignocellulosic biomass. During dilute acid pretreatment, xylan depolymerizes to form soluble xylose monomers and oligomers. Because the xylan found in nature is highly acetylated, the formation of xylose monomers requires two steps: (1) cleavage of the xylosidic bonds, and (2) cleavage of covalently bonded acetyl ester groups. Results: In this study, we show that the latter may be the rate limiting step for xylose monomer formation. Furthermore, acetyl groups are also found to be a cause of biomass recalcitrance and hydrolyzate toxicity. While the removal of acetyl groups from native corn stover by alkaline de-esterification prior to pretreatment improves overall process yields, the exact impact is highly dependent on the corn stover variety in use. Xylose monomer yields in pretreatment generally increases by greater than 10%. Compared to pretreated corn stover controls, the deacetylated corn stover feedstock is approximately 20% more digestible after pretreatment. Finally, by lowering hydrolyzate toxicity, xylose utilization and ethanol yields are further improved during fermentation by roughly 10% and 7%, respectively. In this study, several varieties of corn stover lots were investigated to test the robustness of the deacetylation-pretreatment-saccharification-fermentation process. Conclusions:more » Deacetylation shows significant improvement on glucose and xylose yields during pretreatment and enzymatic hydrolysis, but it also reduces hydrolyzate toxicity during fermentation, thereby improving ethanol yields and titer. The magnitude of effect is dependent on the selected corn stover variety, with several varieties achieving improvements of greater than 10% xylose yield in pretreatment, 20% glucose yield in low solids enzymatic hydrolysis and 7% overall ethanol yield.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
OSTI Identifier:
1039090
Report Number(s):
NREL/JA-5100-53651
Journal ID: ISSN 1754-6834; TRN: US201209%%153
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Journal Name:
Biotechnology for Biofuels
Additional Journal Information:
Journal Volume: 5; Journal Issue: 1; Journal ID: ISSN 1754-6834
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; 59 BASIC BIOLOGICAL SCIENCES; AGRICULTURAL WASTES; BIOETHANOL; BIOMASS; CLEAVAGE; DEPOLYMERIZATION; ENZYMATIC HYDROLYSIS; ESTERS; ETHANOL; FERMENTATION; GLUCOSE; MAIZE; MONOMERS; PRODUCTION; REMOVAL; TOXICITY; XYLANS; XYLOSE; bioethanol; pretreatment; enzymatic hydrolysis; fermentation; deacetylation

Citation Formats

Chen, Xiaowen, Shekiro, Joseph, Franden, Mary Ann, Wang, Wei, Johnson, David K., Zhang, Min, Kuhn, E., and Tucker, Melvin P. Impacts of Deacetylation Prior to Dilute Acid Pretreatment on the Bioethanol Process. United States: N. p., 2011. Web. doi:10.1186/1754-6834-5-8.
Chen, Xiaowen, Shekiro, Joseph, Franden, Mary Ann, Wang, Wei, Johnson, David K., Zhang, Min, Kuhn, E., & Tucker, Melvin P. Impacts of Deacetylation Prior to Dilute Acid Pretreatment on the Bioethanol Process. United States. doi:10.1186/1754-6834-5-8.
Chen, Xiaowen, Shekiro, Joseph, Franden, Mary Ann, Wang, Wei, Johnson, David K., Zhang, Min, Kuhn, E., and Tucker, Melvin P. Thu . "Impacts of Deacetylation Prior to Dilute Acid Pretreatment on the Bioethanol Process". United States. doi:10.1186/1754-6834-5-8.
@article{osti_1039090,
title = {Impacts of Deacetylation Prior to Dilute Acid Pretreatment on the Bioethanol Process},
author = {Chen, Xiaowen and Shekiro, Joseph and Franden, Mary Ann and Wang, Wei and Johnson, David K. and Zhang, Min and Kuhn, E. and Tucker, Melvin P.},
abstractNote = {Dilute acid pretreatment is a promising pretreatment technology for the biochemical production of ethanol from lignocellulosic biomass. During dilute acid pretreatment, xylan depolymerizes to form soluble xylose monomers and oligomers. Because the xylan found in nature is highly acetylated, the formation of xylose monomers requires two steps: (1) cleavage of the xylosidic bonds, and (2) cleavage of covalently bonded acetyl ester groups. Results: In this study, we show that the latter may be the rate limiting step for xylose monomer formation. Furthermore, acetyl groups are also found to be a cause of biomass recalcitrance and hydrolyzate toxicity. While the removal of acetyl groups from native corn stover by alkaline de-esterification prior to pretreatment improves overall process yields, the exact impact is highly dependent on the corn stover variety in use. Xylose monomer yields in pretreatment generally increases by greater than 10%. Compared to pretreated corn stover controls, the deacetylated corn stover feedstock is approximately 20% more digestible after pretreatment. Finally, by lowering hydrolyzate toxicity, xylose utilization and ethanol yields are further improved during fermentation by roughly 10% and 7%, respectively. In this study, several varieties of corn stover lots were investigated to test the robustness of the deacetylation-pretreatment-saccharification-fermentation process. Conclusions: Deacetylation shows significant improvement on glucose and xylose yields during pretreatment and enzymatic hydrolysis, but it also reduces hydrolyzate toxicity during fermentation, thereby improving ethanol yields and titer. The magnitude of effect is dependent on the selected corn stover variety, with several varieties achieving improvements of greater than 10% xylose yield in pretreatment, 20% glucose yield in low solids enzymatic hydrolysis and 7% overall ethanol yield.},
doi = {10.1186/1754-6834-5-8},
journal = {Biotechnology for Biofuels},
issn = {1754-6834},
number = 1,
volume = 5,
place = {United States},
year = {2011},
month = {12}
}