Steam explosion pretreatment of softwood: the effect of the explosive decompression on enzymatic digestibility

Pielhop, Thomas; Amgarten, Janick; Rohr, Philipp Rudolf von; Studer, Michael Hans-Peter

doi:10.1186/s13068-016-0567-1

Cited by 213 publications

(101 citation statements)

References 30 publications

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“…The increase in glucose yield from 5.1% in steam-treated wood to 9.8% in steam-exploded wood is a result of physical structural modification. Pielhop et al (2016) also observed 90% increase in digestibility of cellulose in steam exploded wood as compared to steam-treated wood. The chemical changes during the steam-treatment step (i.e., the hydrolysis of hemicelluloses and redistribution of lignin) increased the accessibility of enzymes to celluloses and resulted in greater cellulose hydrolysis.…”

Section: Resultsmentioning

confidence: 61%

Contribution of Structural Modification to Enhanced Enzymatic Hydrolysis and 3-D Structural Analysis of Steam-Exploded Wood using X-Ray Tomography

Muzamal¹,

Bååth²,

Olsson³

et al. 2016

BioResources

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Steam explosion pretreatment modifies both the chemical and physical structures of a biomass. Chemical modifications are generated during the treatment of biomass with steam at high temperature. Physical modifications are created during the explosion step, which produces disintegrated and defibrillated biomass. In this study, the contribution of each modification to an increase in enzymatic hydrolysis has been studied. It was found that both physical and chemical modifications contributed to an increase in enzymatic hydrolysability. Additionally, high resolution Xray tomography was performed to identify the structural modification created during the steam explosion process. Comparison of the 3-D microstructure of a steam-exploded wood sample with an untreated wood sample revealed that several kinds of cracks were created during the explosion step, and the micro-structure of the wood sample was vigorously destroyed.

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Section: Resultsmentioning

confidence: 61%

Contribution of Structural Modification to Enhanced Enzymatic Hydrolysis and 3-D Structural Analysis of Steam-Exploded Wood using X-Ray Tomography

Muzamal¹,

Bååth²,

Olsson³

et al. 2016

BioResources

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“…Alternatively, the pressure can also be released via a hand valve at the bottom of the reactor into a secondary tank. More details on the steam explosion system (steam generation and injection, removal of entrapped air, construction details and schematic drawing) can be found elsewhere [27]. …”

Section: Methodsmentioning

confidence: 99%

“…The biomass filter cake was not washed and its dry matter content was determined in duplicate. More details on the pretreatment procedure (preheating of reactor, time measurement, experiments without explosion) can be found elsewhere [27]. …”

Section: Methodsmentioning

confidence: 99%

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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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“…Instead, a genetically modified strain was developed to omit the detoxification process [15]. Another method is the organosolv method such as used on Oil Palm fronds [16], wheat straw [17] the steam explosion on sugarcane bagasse [18], sugarcane straw [19], wheat straw [20], spruce wood chips [21]. These methods partially hydrolyzes lignin bond with cellulose and hemicellulose but most of the hemicellulose are solubilized [22].…”

Section: Introductionmentioning

confidence: 99%

Temperature, Solid Loading and Time Effects on Recovery of Sugar from OPEFB

2018

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Abstract. Biorefinery industry used lignocellulosic biomass as the raw material. Oil Palm Empty Fruit Bunch (OPEFB) is one of Indonesian potential lignocellulosic biomass, which consists of hemicellulose with xylan as the main component. Xylitol production via fermentation could use this xylan since it can be converted into xylose. However, the structure of OPEFB is such that hemicellulose is protected in a way that will hinder hydrolysis enzyme to access it. Considering that hemicellulose is more susceptible to heat than cellulose, a hydrothermal process was applied to pre-treat OPEFB before it was hydrolyzed enzymatically. The aim of the research is to map the effect of temperature, solid loading and time of pre-treatment process to obtain and recover as much as possible accessible hemicellulose from OPEFB. The results showed that temperature gave more significant effect than time and solid loading for glucose recovery of OPEFB residues. While xylose recovery varies greatly with temperature, but solid loading and time gave less significant effect.

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Steam explosion pretreatment of softwood: the effect of the explosive decompression on enzymatic digestibility

Cited by 213 publications

References 30 publications

Contribution of Structural Modification to Enhanced Enzymatic Hydrolysis and 3-D Structural Analysis of Steam-Exploded Wood using X-Ray Tomography

Contribution of Structural Modification to Enhanced Enzymatic Hydrolysis and 3-D Structural Analysis of Steam-Exploded Wood using X-Ray Tomography

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

Temperature, Solid Loading and Time Effects on Recovery of Sugar from OPEFB

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