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Biochemical Conversion of Torrefied Norway Spruce After Pretreatment with Acid or Ionic Liquid
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
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2016 (English)In: Bioenergy Research, ISSN 1939-1234, E-ISSN 1939-1242, Vol. 9, no 1, 355-368 p.Article in journal (Refereed) PublishedText
Abstract [en]

The chemical effects of torrefaction and the possibility to combine torrefaction with biochemical conversion were explored in experiments with five preparations of wood of Norway spruce that had been torrefied using different degrees of severity. Compositional analysis and analyses using solid-state CP/MAS C-13 NMR, Fourier-transform infrared (FTIR) spectroscopy, and Py-GC/MS showed small gradual changes, such as decreased hemicellulosic content and increased Klason lignin value, for torrefaction conditions in the range from 260 A degrees C and 8 min up to 310 A degrees C and 8 min. The most severe torrefaction conditions (310 A degrees C, 25 min) resulted in substantial loss of glucan and further increase of the Klason lignin value, which was attributed to conversion of carbohydrate to pseudo-lignin. Even mild torrefaction conditions led to decreased susceptibility to enzymatic hydrolysis of cellulose, a state which was not changed by pretreatment with sulfuric acid. Pretreatment with the ionic liquid (IL) 1-butyl-3-methylimidazolium acetate overcame the additional recalcitrance caused by torrefaction, and the glucose yields after 72 h of enzymatic hydrolysis of wood torrefied at 260 A degrees C for 8 min and at 285 A degrees C for 16.5 min were as high as that of IL-pretreated non-torrefied spruce wood. Compared to IL-pretreated non-torrefied reference wood, the glucose production rates after 2 h of enzymatic hydrolysis of IL-pretreated wood torrefied at 260 A degrees C for 8 min and at 285 A degrees C for 16.5 min were 63 and 40 % higher, respectively. The findings offer increased understanding of the effects of torrefaction and indicate that mild torrefaction is compatible with biochemical conversion after pretreatment with alternative solvents that disrupt pseudo-lignin-containing lignocellulose.

Place, publisher, year, edition, pages
2016. Vol. 9, no 1, 355-368 p.
Keyword [en]
Torrefaction, Wood, Acid pretreatment, Ionic liquid, Enzymatic hydrolysis
National Category
Other Chemistry Topics
URN: urn:nbn:se:umu:diva-118386DOI: 10.1007/s12155-015-9698-7ISI: 000370816300032OAI: diva2:922411
Available from: 2016-04-22 Created: 2016-03-18 Last updated: 2016-10-07Bibliographically approved
In thesis
1. Pretreatment and enzymatic saccharification of lignocellulose: formation and effects of pseudolignin
Open this publication in new window or tab >>Pretreatment and enzymatic saccharification of lignocellulose: formation and effects of pseudolignin
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Production of advanced biofuels, green chemicals, and bio-based materials from renewable lignocellulosic biomass would contribute to decreased dependence on fossil resources and to sustainable development. The overall aim of the investigations was to explore how preprocessing and pretreatment technologies affected the chemical composition of cellulosic materials and their susceptibility to enzymatic saccharification, which is one of the major routes for biorefining of lignocellulose. Special attention was given to formation and effects of pseudolignin, an aromatic substance derived from polysaccharides. Pseudolignin is formed during dry thermal preprocessing, such as torrefaction, and during dilute-acid pretreatment, techniques that are highly relevant for biorefining of wood.

The susceptibility of seven fractions of Scots pine to dilute-acid pretreatment and enzymatic saccharification was investigated. Harsh pretreatment conditions led to slow initial conversion, which was tentatively attributed to pseudolignin. Pretreatment with ionic liquids was investigated using substrates consisting of crystalline and amorphous cellulose, hemicelluloses, and wood. The susceptibility of torrefied spruce wood to enzymatic saccharification after pretreatment with acid or ionic liquid was investigated. The results showed that the negative effects of mild torrefaction on enzymatic saccharification were possible to overcome using pretreatment with the ionic liquid. In a subsequent study, the possibility to dissolve pseudolignin with ionic liquids and conventional solvents was explored. The effects of pseudolignin on wood polysaccharides and enzymatic saccharification were further studied using NMR, FTIR, XPS, TOF-SIMS, and SEM. The surface-sensitive analytical methods TOF-SIMS, XPS, and SEM revealed how pseudolignin formed a coat on the surface of the polysaccharide, which could explain the effects on the enzymatic saccharification.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 2016. 67 p.
Pretreatment, enzymatic saccharification, ionic liquid, torrefaction, pseudolignin
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
urn:nbn:se:umu:diva-126463 (URN)978-91-7601-575-9 (ISBN)
Public defence
2016-10-28, KB3B1, KBC-huset, Linnaeus väg 6, 907 36, Umeå, 13:00 (English)
Available from: 2016-10-07 Created: 2016-10-06 Last updated: 2016-10-07Bibliographically approved

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Normark, MonicaPommer, LindaHedenström, MattiasGorzsas, AndrasWinestrand, SandraJönsson, Leif J.
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