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Two-step steam pretreatment of softwood by dilute H2SO4 impregnation for ethanol production

Söderström, Johanna LU ; Pilcher, Linda LU ; Galbe, Mats LU and Zacchi, Guido LU (2003) In Biomass & Bioenergy 24(6). p.475-486
Abstract
Fuel ethanol can be produced from softwood through hydrolysis in an enzymatic process. Prior to enzymatic hydrolysis of the softwood, pretreatment is necessary. In this study two-step steam pretreatment by dilute H2SO4 impregnation to improve the overall sugar and ethanol yield has been investigated. The first pretreatment step was performed under conditions of low severity (180°C, 10 min, 0.5% H2SO4) to optimise the amount of hydrolysed hemicellulose. In the second step the washed solid material from the first pretreatment step was impregnated again with H2SO4 and pretreated under conditions of higher severity to hydrolyse a portion of the cellulose, and to make the cellulose more accessible to enzymatic attack. A wide range of conditions... (More)
Fuel ethanol can be produced from softwood through hydrolysis in an enzymatic process. Prior to enzymatic hydrolysis of the softwood, pretreatment is necessary. In this study two-step steam pretreatment by dilute H2SO4 impregnation to improve the overall sugar and ethanol yield has been investigated. The first pretreatment step was performed under conditions of low severity (180°C, 10 min, 0.5% H2SO4) to optimise the amount of hydrolysed hemicellulose. In the second step the washed solid material from the first pretreatment step was impregnated again with H2SO4 and pretreated under conditions of higher severity to hydrolyse a portion of the cellulose, and to make the cellulose more accessible to enzymatic attack. A wide range of conditions was used to determine the most favourable combination. The temperatures investigated were between 180°C and 220°C, the residence times were 2, 5 and 10 min and the concentrations of H2SO4 were 1% and 2%.



The effects of pretreatment were assessed by both enzymatic hydrolysis of the solids and with simultaneous saccharification and fermentation (SSF) of the whole slurry, after the second pretreatment step. For each set of pretreatment conditions the liquid fraction was fermented to determine any inhibiting effects. The ethanol yield using the SSF configuration reached 65% of the theoretical value while the sugar yield using the SHF configuration reached 77%. Maximum yields were obtained when the second pretreatment step was performed at 200°C for 2 min with 2% H2SO4. This form of two-step steam pretreatment is a promising method of increasing the overall yield in the wood-to-ethanol process. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biomass & Bioenergy
volume
24
issue
6
pages
475 - 486
publisher
Elsevier
external identifiers
  • wos:000182418400006
  • scopus:0242584369
ISSN
1873-2909
DOI
language
English
LU publication?
yes
id
6d91589a-c4a0-4408-9b33-ad6c841f7631 (old id 129393)
date added to LUP
2007-06-25 16:17:18
date last changed
2018-05-29 09:55:36
@article{6d91589a-c4a0-4408-9b33-ad6c841f7631,
  abstract     = {Fuel ethanol can be produced from softwood through hydrolysis in an enzymatic process. Prior to enzymatic hydrolysis of the softwood, pretreatment is necessary. In this study two-step steam pretreatment by dilute H2SO4 impregnation to improve the overall sugar and ethanol yield has been investigated. The first pretreatment step was performed under conditions of low severity (180°C, 10 min, 0.5% H2SO4) to optimise the amount of hydrolysed hemicellulose. In the second step the washed solid material from the first pretreatment step was impregnated again with H2SO4 and pretreated under conditions of higher severity to hydrolyse a portion of the cellulose, and to make the cellulose more accessible to enzymatic attack. A wide range of conditions was used to determine the most favourable combination. The temperatures investigated were between 180°C and 220°C, the residence times were 2, 5 and 10 min and the concentrations of H2SO4 were 1% and 2%.<br/><br>
<br/><br>
The effects of pretreatment were assessed by both enzymatic hydrolysis of the solids and with simultaneous saccharification and fermentation (SSF) of the whole slurry, after the second pretreatment step. For each set of pretreatment conditions the liquid fraction was fermented to determine any inhibiting effects. The ethanol yield using the SSF configuration reached 65% of the theoretical value while the sugar yield using the SHF configuration reached 77%. Maximum yields were obtained when the second pretreatment step was performed at 200°C for 2 min with 2% H2SO4. This form of two-step steam pretreatment is a promising method of increasing the overall yield in the wood-to-ethanol process.},
  author       = {Söderström, Johanna and Pilcher, Linda and Galbe, Mats and Zacchi, Guido},
  issn         = {1873-2909},
  language     = {eng},
  number       = {6},
  pages        = {475--486},
  publisher    = {Elsevier},
  series       = {Biomass & Bioenergy},
  title        = {Two-step steam pretreatment of softwood by dilute H2SO4 impregnation for ethanol production},
  url          = {http://dx.doi.org/},
  volume       = {24},
  year         = {2003},
}