The influence of SO2 and H2SO4 impregnation of willow prior to steam pretreatment

Eklund, Robert; Galbe, Mats; Zacchi, Guido

doi:10.1016/0960-8524(95)00042-d

Cited by 79 publications

(30 citation statements)

References 7 publications

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“…An increase in sugar conversion was observed with increasing biomass acid loading, suggesting that xylan removal is positively correlated with cellulose digestibility when xylose degradation to furfural is minimal [14]. This result is in agreement with previous studies conducted on agricultural residues and woody biomass [1,7]. As the acid loading in pretreatment increased to 0.025 g acid/g corn stover, the overall sugar conversion was slightly higher than that achieved with 0.05 g acid/g corn stover.…”

Section: Enzymatic Hydrolysis Of Pretreated Corn Stoversupporting

confidence: 94%

Reducing acid in dilute acid pretreatment and the impact on enzymatic saccharification

Chen

Stevens

Zhu

et al. 2012

Journal of Industrial Microbiology and Biotechnology

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Dilute acid pretreatment is a leading pretreatment technology for biomass to ethanol conversion due to the comparatively low chemical cost and effective hemicellulose solubilization. The conventional dilute acid pretreatment processes use relatively large quantities of sulfuric acid and require alkali for pH adjustment afterwards. Significant amounts of sulfate salts are generated as by-products, which have to be properly treated before disposal. Wastewater treatment is an expensive, yet indispensable part of commercial level biomass-to-ethanol plants. Therefore, reducing acid use to the lowest level possible would be of great interest to the emerging biomass-to-ethanol industry. In this study, a dilute acid pretreatment process was developed for the pretreatment of corn stover. The pretreatment was conducted at lower acid levels than the conventional process reported in the literature while using longer residence times. The study indicates that a 50% reduction in acid consumption can be achieved without compromising pretreatment efficiency when the pretreatment time was extended from 1-5 min to 15-20 min. To avoid undesirable sugar degradation and inhibitor generation, temperatures should be controlled below 170°C. When the sulfuric acid-to-lignocellulosic biomass ratio was kept at 0.025 g acid/g dry biomass, a cellulose-to-glucose conversion of 72.7% can be achieved at an enzyme loading of 0.016 g/g corn stover. It was also found that acid loading based on total solids (g acid/g dry biomass) governs the pretreatment efficiency rather than the acid concentration (g acid/g pretreatment liquid). While the acid loading on lignocellulosic biomass may be achieved through various combinations of solids loading and acid concentration in the pretreatment step, this work shows that it is unlikely to reduce acid use without undermining pretreatment efficiency simply by increasing the solid content in pretreatment reactors, therefore acid loading on biomass is indicated to be the key factor in effective dilute acid pretreatment.

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Section: Enzymatic Hydrolysis Of Pretreated Corn Stoversupporting

confidence: 94%

Reducing acid in dilute acid pretreatment and the impact on enzymatic saccharification

Chen

Stevens

Zhu

et al. 2012

Journal of Industrial Microbiology and Biotechnology

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“…Although some workers have reported high recoveries from hardwoods such as aspen (Mackie et al, 1985) and willow (Eklund et al, 1995), considerably lower recoveries have generally been reported for softwoods (Clark and Mackie, 1987;Schwald et al, 1989). However, our work agreed with the previous observations that best hemicellulose recoveries were obtained at relatively low-severity conditions (severity factor lower than 3.5) which corresponded to temperatures of 200°C or slightly lower.…”

Section: Resultsmentioning

confidence: 94%

Fermentability of the hemicellulose-derived sugars from steam-exploded softwood (douglas fir)

Boussaid

Robinson

Cai

et al. 1999

Biotechnol. Bioeng.

102

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“…The use of dilute H 2 SO 4 also results in greater steam consumption, while SO 2 increases the extent to which lignin can be extracted from the water-washed steam-exploded fibers with caustic 54 . Another comparative study involving SO 2 and H 2 SO 4 as pretreatment catalysts has been carried out by Eklund et al 103 using willow (Salix caprea). Pre-impregnation was performed with 0-3% H 2 SO 4 or 1% SO 2 (w/w substrate) and pretreatment was carried out at temperatures in the range 160-230°C for 10 min.…”

Section: Steam Pretreatment (Steam Explosion)mentioning

confidence: 99%

The chemistry involved in the steam treatment of lignocellulosic materials

Ramos¹

2003

Quím. Nova

541

217

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Recebido em 16/8/02; aceito em 15/5/03Pretreatment of lignocellulosic materials is essential for bioconversion because of the various physical and chemical barriers that greatly inhibit their susceptibility to bioprocesses such as hydrolysis and fermentation. The aim of this article is to review some of the most important pretreatment methods developed to date to enhance the conversion of lignocellulosics. Steam explosion, which precludes the treatment of biomass with high-pressure steam under optimal conditions, is presented as the pretreatment method of choice and its mode of action on lignocellulosics is discussed. The optimal pretreatment conditions for a given plant biomass are defined as those in which the best substrate for hydrolysis is obtained with the least amount of soluble sugars lost to side reactions such as dehydration. Therefore, pretreatment optimization results from a compromise between two opposite trends because hemicellulose recovery in acid hydrolysates can only be maximized at lower pretreatment severities, whereas the development of substrate accessibility requires more drastic pretreatment conditions in which sugar losses are inevitable. To account for this heterogeneity, the importance of several process-oriented parameters is discussed in detail, such as the pretreatment temperature, residence time into the steam reactor, use of an acid catalyst, susceptibility of the pretreated biomass to bioconversion, and process design.

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The influence of SO2 and H2SO4 impregnation of willow prior to steam pretreatment

Cited by 79 publications

References 7 publications

Reducing acid in dilute acid pretreatment and the impact on enzymatic saccharification

Reducing acid in dilute acid pretreatment and the impact on enzymatic saccharification

Fermentability of the hemicellulose-derived sugars from steam-exploded softwood (douglas fir)

The chemistry involved in the steam treatment of lignocellulosic materials

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