Autohydrolysis pretreatment of softwood – enhancement by phenolic additives and the effects of other compounds

Pielhop, Thomas; Larrazábal, Gastón O.; Rohr, Philipp Rudolf von

doi:10.1039/c6gc01447j

Cited by 54 publications

(43 citation statements)

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“…The selected studies use spruce or pine as feedstock, which were shown to have a very similar behavior of recalcitrance and can equally profit from the addition of 2-naphthol to pretreatment [40]. The studies employ a solid content in enzymatic hydrolysis of 2–3% w/w, which is in good agreement with the solid content in the hydrolysis of the 2-naphthol experiments (2.2–3.0% w/w) and allows for a good comparability.…”

Section: Resultsmentioning

confidence: 99%

Pilot-scale steam explosion pretreatment with 2-naphthol to overcome high softwood recalcitrance

Pielhop

Amgarten

Studer

et al. 2017

Biotechnol Biofuels

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BackgroundSteam explosion pretreatment has been examined in many studies for enhancing the enzymatic digestibility of lignocellulosic biomass and is currently the most common pretreatment method in commercial biorefineries. It is however not effective for overcoming the extremely high recalcitrance of softwood to biochemical conversion. Recent fundamental research in small-scale liquid hot water pretreatment has shown, though, that the addition of a carbocation scavenger like 2-naphthol can prevent lignin repolymerization and thus enhance the enzymatic digestibility of softwood cellulose. This work studies the technical application potential of this approach in a larger steam explosion pilot plant for surmounting softwood recalcitrance.ResultsThe addition of 35.36 g 2-naphthol to the steam explosion pretreatment of 1.5 kg spruce wood chips allowed to considerably enhance the enzymatic cellulose digestibility. Different ways of adding the solid 2-naphthol to steam pretreatment were tested. Mixing with the biomass before pretreatment could enhance digestibility by up to 55% compared to control experiments. Impregnation of the biomass with 2-naphthol was yet more effective. Acetone and ethanol were tested to dissolve 2-naphthol and impregnate the biomass. The solvents were then removed again by evaporation before the pretreatment. The impregnation allowed to enhance digestibility by up to 179 and 192%, respectively. A comparison to prevalent acid-catalyzed steam explosion pretreatments for softwood revealed that the scavenger approach allows for obtaining exceptionally high yields in enzymatic hydrolysis. The biomass impregnation with 2-naphthol even renders a complete enzymatic cellulose conversion possible, which is remarkable for a softwood pretreatment not removing lignin. Steam pretreatment experiments without explosive decompression revealed that the enhancing effects of the explosion and the scavenger complement each other well. The explosion enhances the accessibility of the cellulose while the use of the scavenger reduces particularly the deactivation of enzymes.ConclusionsThis is the first study to show that a carbocation scavenger in steam pretreatment can enhance the enzymatic digestibility of lignocellulosic biomass. The approach opens up a novel possibility for overcoming the high softwood recalcitrance in a process that does not require an acid catalyst or the removal of lignin from the biomass.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0816-y) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Pilot-scale steam explosion pretreatment with 2-naphthol to overcome high softwood recalcitrance

Pielhop

Amgarten

Studer

et al. 2017

Biotechnol Biofuels

Self Cite

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“…Pretreatment conditions not only affect saccharification yields 12 but also suitability of the lignin for value-added applications. Lignins isolated around the optimal intensified pretreatment conditions were therefore analysed for their chemical properties.…”

Section: Lignin Characterisationmentioning

confidence: 99%

“…Lignocellulose is recalcitrant and requires a pretreatment step in order to release the majority of sugar contained within. 7 Various pretreatment methods are currently under development, such as steam explosion, 8 AFEX, 9 concentrated acid, 10 dilute acid, 11 hot water, 12 organosolv 13,14 and ionic liquid pretreatments, [15][16][17] including ionoSolv fractionation. 18,19 Different strategies are followed, from disrupting the lignocellulosic cell wall structure without separation, [20][21][22][23] to selectively isolating lignin, hemicelluloses and cellulose.…”

Section: Introductionmentioning

confidence: 99%

Rapid pretreatment of Miscanthus using the low-cost ionic liquid triethylammonium hydrogen sulfate at elevated temperatures

et al. 2018

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Deconstruction with low-cost ionic liquids (ionoSolv) is a promising method to pre-condition lignocellulosic biomass for the production of renewable fuels, materials and chemicals. This study investigated process intensification strategies for ionoSolv pretreatment of Miscanthus × giganteus with the low-cost ionic liquid triethylammonium hydrogen sulfate ([TEA] [HSO 4 ]) in the presence of 20 wt% water, using high temperatures and a high solid to solvent loading of 1 : 5 g/g. The temperatures investigated were 150, 160, 170 and 180°C. We discuss the effect of pretreatment temperature on lignin and hemicellulose removal, cellulose degradation and enzymatic saccharification yields. We report that very good fractionation can be achieved across all investigated temperatures, including an enzymatic saccharification yield exceeding 75% of the theoretical maximum after only 15 min of treatment at 180°C. We further characterised the recovered lignins, which established some tunability of the hydroxyl group content, subunit composition, connectivity and molecular weight distribution in the isolated lignin while maintaining maximum saccharification yield. This drastic reduction of pretreatment time at increased biomass loading without a yield penalty is promising for the development of a commercial ionoSolv pretreatment process.

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“…Most of these reactions take place at the aliphatic chain and beneficially block the lignin condensation reactions. Obvious examples are alkoxylation Kubo, Kadla 2004;Lancefield et al 2017) and sulphonation (Lou et al 2013;Zhou et al 2013b) at the C-α position, and reactions with so-called carbocation scavengers supplemented to autohydrolysis pretreatments Pielhop et al 2016;. Acidic hydrothermal processes form resinous degradation products, termed pseudo-lignin or humins, which resemble lignin in terms of structural features Van Zandvoort et al 2013) and in their detrimental adsorption of cellulases ).…”

Section: Structural Changes In Lignin During Common Lignocellulose Prmentioning

confidence: 99%

Structural changes of lignin in biorefinery pretreatments and consequences to enzyme-lignin interactions

Sipponen¹,

Rahikainen²,

Leskinen³

et al. 2019

[Set Bioenergy, Vol. 1+2]

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Please cite the original version:Sipponen, M., Rahikainen, J., Leskinen, T., Pihlajaniemi, V., Mattinen, M-L., Lange, H., ... Österberg, M. (2017). Structural changes of lignin in biorefinery pretreatments and consequences to enzyme-lignin interactions. ABSTRACT:The main target of a biorefinery pretreatment process is to break down the ligninreinforced plant cell wall structure prior to enzymatic hydrolysis of polysaccharides to fermentable sugars. Various physico-chemical alterations occur in lignin during the biomass pretreatment, but effects of those structural changes on subsequent enzymatic hydrolysis have remained ambiguous. We review the reinforcing and detrimental lignin-enzyme interactions and their underlying mechanisms, and use this structure-function information to assess critical features of current and emerging pretreatment technologies. Our perspective is that truly multidisciplinary research is needed to develop pretreatments that render lignin non-inhibiting to enzymes and with high potential for further valorisation. ADDRESSES OF THE AUTHORS: Mika HenrikkiSipponen (mika.sipponen@aalto.fi), Timo Leskinen (timo.leskinen@aalto.fi), Maija-Liisa Mattinen (maijaliisa.mattinen@aalto.fi), Monika Österberg

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Autohydrolysis pretreatment of softwood – enhancement by phenolic additives and the effects of other compounds

Abstract: The effects of different additives on lignin repolymerisation in the autohydrolysis pretreatment of softwood and the consequences for enzymatic cellulose digestibility have been studied.

Cited by 54 publications

References 15 publications

Pilot-scale steam explosion pretreatment with 2-naphthol to overcome high softwood recalcitrance

Pilot-scale steam explosion pretreatment with 2-naphthol to overcome high softwood recalcitrance

Rapid pretreatment of Miscanthus using the low-cost ionic liquid triethylammonium hydrogen sulfate at elevated temperatures

Structural changes of lignin in biorefinery pretreatments and consequences to enzyme-lignin interactions

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