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Impact of dual temperature profile in dilute acid hydrolysis of spruce for ethanol production.

Bösch, Peter; Wallberg, Ola LU ; Joelsson, Elisabeth LU ; Galbe, Mats LU and Zacchi, Guido LU (2010) In Biotechnology for Biofuels 3.
Abstract
ABSTRACT: BACKGROUND: The two-step dilute acid hydrolysis (DAH) of softwood is costly in energy demands and capital costs. However, it has the advantage that hydrolysis and subsequent removal of hemicellulose-derived sugars can be carried out under conditions of low severity, resulting in a reduction in the level of sugar degradation products during the more severe subsequent steps of cellulose hydrolysis. In this paper, we discuss a single-step DAH method that incorporates a temperature profile at two levels. This profile should simulate the two-step process while removing its major disadvantage, that is, the washing step between the runs, which leads to increased energy demand. RESULTS: The experiments were conducted in a reactor with a... (More)
ABSTRACT: BACKGROUND: The two-step dilute acid hydrolysis (DAH) of softwood is costly in energy demands and capital costs. However, it has the advantage that hydrolysis and subsequent removal of hemicellulose-derived sugars can be carried out under conditions of low severity, resulting in a reduction in the level of sugar degradation products during the more severe subsequent steps of cellulose hydrolysis. In this paper, we discuss a single-step DAH method that incorporates a temperature profile at two levels. This profile should simulate the two-step process while removing its major disadvantage, that is, the washing step between the runs, which leads to increased energy demand. RESULTS: The experiments were conducted in a reactor with a controlled temperature profile. The total dry matter content of the hydrolysate was up to 21.1% w/w, corresponding to a content of 15.5% w/w of water insoluble solids. The highest measured glucose yield, (18.3 g glucose per 100 g dry raw material), was obtained after DAH cycles of 3 min at 209 degrees C and 6 min at 211 degrees C with 1% H2SO4, which resulted in a total of 26.3 g solubilized C6 sugars per 100 g dry raw material. To estimate the remaining sugar potential, enzymatic hydrolysis (EH) of the solid fraction was also performed. EH of the solid residue increased the total level of solubilized C6 sugars to a maximum of 35.5 g per 100 g dry raw material when DAH was performed as described above (3 min at 210 degrees C and 2 min at 211 degrees C with 1% H2SO4). CONCLUSION: The dual-temperature DAH method did not yield decisively better results than the single-temperature, one-step DAH. When we compared the results with those of earlier studies, the hydrolysis performance was better than with the one-step DAH but not as well as that of the two-step, single-temperature DAH. Additional enzymatic hydrolysis resulted in lower levels of solubilized sugars compared with other studies on one-step DAH and two-step DAH followed by enzymatic hydrolysis. A two-step steam pretreatment with EH gave rise to a considerably higher sugar yield in this study. (Less)
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organization
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type
Contribution to journal
publication status
published
subject
in
Biotechnology for Biofuels
volume
3
publisher
BioMed Central
external identifiers
  • wos:000280326500001
  • pmid:20594309
ISSN
1754-6834
DOI
10.1186/1754-6834-3-15
language
English
LU publication?
yes
id
e3c74ac1-c52b-40fb-a357-148d9d4cda17 (old id 1645348)
date added to LUP
2010-08-18 11:06:03
date last changed
2018-05-29 09:24:03
@article{e3c74ac1-c52b-40fb-a357-148d9d4cda17,
  abstract     = {ABSTRACT: BACKGROUND: The two-step dilute acid hydrolysis (DAH) of softwood is costly in energy demands and capital costs. However, it has the advantage that hydrolysis and subsequent removal of hemicellulose-derived sugars can be carried out under conditions of low severity, resulting in a reduction in the level of sugar degradation products during the more severe subsequent steps of cellulose hydrolysis. In this paper, we discuss a single-step DAH method that incorporates a temperature profile at two levels. This profile should simulate the two-step process while removing its major disadvantage, that is, the washing step between the runs, which leads to increased energy demand. RESULTS: The experiments were conducted in a reactor with a controlled temperature profile. The total dry matter content of the hydrolysate was up to 21.1% w/w, corresponding to a content of 15.5% w/w of water insoluble solids. The highest measured glucose yield, (18.3 g glucose per 100 g dry raw material), was obtained after DAH cycles of 3 min at 209 degrees C and 6 min at 211 degrees C with 1% H2SO4, which resulted in a total of 26.3 g solubilized C6 sugars per 100 g dry raw material. To estimate the remaining sugar potential, enzymatic hydrolysis (EH) of the solid fraction was also performed. EH of the solid residue increased the total level of solubilized C6 sugars to a maximum of 35.5 g per 100 g dry raw material when DAH was performed as described above (3 min at 210 degrees C and 2 min at 211 degrees C with 1% H2SO4). CONCLUSION: The dual-temperature DAH method did not yield decisively better results than the single-temperature, one-step DAH. When we compared the results with those of earlier studies, the hydrolysis performance was better than with the one-step DAH but not as well as that of the two-step, single-temperature DAH. Additional enzymatic hydrolysis resulted in lower levels of solubilized sugars compared with other studies on one-step DAH and two-step DAH followed by enzymatic hydrolysis. A two-step steam pretreatment with EH gave rise to a considerably higher sugar yield in this study.},
  articleno    = {15},
  author       = {Bösch, Peter and Wallberg, Ola and Joelsson, Elisabeth and Galbe, Mats and Zacchi, Guido},
  issn         = {1754-6834},
  language     = {eng},
  publisher    = {BioMed Central},
  series       = {Biotechnology for Biofuels},
  title        = {Impact of dual temperature profile in dilute acid hydrolysis of spruce for ethanol production.},
  url          = {http://dx.doi.org/10.1186/1754-6834-3-15},
  volume       = {3},
  year         = {2010},
}