Pretreatment and fractionation of corn stover by ammonia recycle percolation process.
TL;DR: The X-ray crystallography data indicate that the basic crystalline structure of the cellulosic component of corn stover is not altered by the ARP treatment, and low-liquid ARP can reduce the liquid throughput and residence time to 3.3 mL/g-biomass and 10-12 min, without adversely affecting the overall effectiveness.
About: This article is published in Bioresource Technology.The article was published on 2005-12-01. It has received 383 citations till now. The article focuses on the topics: Corn stover & Ammonium hydroxide.
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TL;DR: A review of various pretreatment process methods and the recent literature that has been developed can be found in this paper, where the goal of pretreatment is to make the cellulose accessible to hydrolysis for conversion to fuels.
Abstract: Biofuels produced from various lignocellulosic materials, such as wood, agricultural, or forest residues, have the potential to be a valuable substitute for, or complement to, gasoline. Many physicochemical structural and compositional factors hinder the hydrolysis of cellulose present in biomass to sugars and other organic compounds that can later be converted to fuels. The goal of pretreatment is to make the cellulose accessible to hydrolysis for conversion to fuels. Various pretreatment techniques change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates. During the past few years a large number of pretreatment methods have been developed, including alkali treatment, ammonia explosion, and others. Many methods have been shown to result in high sugar yields, above 90% of the theoretical yield for lignocellulosic biomasses such as woods, grasses, corn, and so on. In this review, we discuss the various pretreatment process methods and the recent literature that...
3,450 citations
TL;DR: A number of different pretreatments involving biological, chemical, physical, and thermal approaches have been investigated over the years, but only those that employ chemicals currently offer the high yields and low costs vital to economic success.
Abstract: New transportation fuels are badly needed to reduce our heavy dependence on imported oil and to reduce the release of greenhouse gases that cause global climate change; cellulosic biomass is the only inexpensive resource that can be used for sustainable production of the large volumes of liquid fuels that our transportation sector has historically favored. Furthermore, biological conversion of cellulosic biomass can take advantage of the power of biotechnology to take huge strides toward making biofuels cost competitive. Ethanol production is particularly well suited to marrying this combination of need, resource, and technology. In fact, major advances have already been realized to competitively position cellulosic ethanol with corn ethanol. However, although biotechnology presents important opportunities to achieve very low costs, pretreatment of naturally resistant cellulosic materials is essential if we are to achieve high yields from biological operations; this operation is projected to be the single, most expensive processing step, representing about 20% of the total cost. In addition, pretreatment has pervasive impacts on all other major operations in the overall conversion scheme from choice of feedstock through to size reduction, hydrolysis, and fermentation, and on to product recovery, residue processing, and co-product potential. A number of different pretreatments involving biological, chemical, physical, and thermal approaches have been investigated over the years, but only those that employ chemicals currently offer the high yields and low costs vital to economic success. Among the most promising are pretreatments using dilute acid, sulfur dioxide, near-neutral pH control, ammonia expansion, aqueous ammonia, and lime, with significant differences among the sugar-release patterns. Although projected costs for these options are similar when applied to corn stover, a key need now is to dramatically improve our knowledge of these systems with the goal of advancing pretreatment to substantially reduce costs and to accelerate commercial applications. © 2007 Society of Chemical Industry and John Wiley & Sons, Ltd
1,671 citations
TL;DR: A survey of biomass pret treatment technologies with emphasis on concepts, mechanism of action and practicability, and the potential for industrial applications of different pretreatment technologies are the highlights of this paper.
1,618 citations
Cites background from "Pretreatment and fractionation of c..."
...The combined physical and chemical changesmarkedly increase the susceptibility of the pretreated lignocellulosic biomass to subsequent enzymatic hydrolysis (Dale et al. 1984; Dale and Moreira 1982; Galbe and Zacchi 2007; Holtzapple et al. 1991; Kim and Lee 2005a)....
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...SAA is a modified version of AFEX utilizing aqueous ammonia to treat biomass in a batch reactor at moderate temperatures (25–60 °C) to reduce the liquid through-put during pretreatment (Kim and Lee 2005a)....
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...Both AFEX and ARP are effective pretreatment for herbaceous plants, agricultural residues and MSW. ARP pretreatment is effective on hardwoods also (Iyer et al. 1996; Kim and Lee 2005b)....
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TL;DR: This review provides a summary and perspective of the extensive research that has been devoted to each of these three interconnected biorefinery aspects, ranging from industrially well-established techniques to the latest cutting edge innovations.
Abstract: In pursuit of more sustainable and competitive biorefineries, the effective valorisation of lignin is key. An alluring opportunity is the exploitation of lignin as a resource for chemicals. Three technological biorefinery aspects will determine the realisation of a successful lignin-to-chemicals valorisation chain, namely (i) lignocellulose fractionation, (ii) lignin depolymerisation, and (iii) upgrading towards targeted chemicals. This review provides a summary and perspective of the extensive research that has been devoted to each of these three interconnected biorefinery aspects, ranging from industrially well-established techniques to the latest cutting edge innovations. To navigate the reader through the overwhelming collection of literature on each topic, distinct strategies/topics were delineated and summarised in comprehensive overview figures. Upon closer inspection, conceptual principles arise that rationalise the success of certain methodologies, and more importantly, can guide future research to further expand the portfolio of promising technologies. When targeting chemicals, a key objective during the fractionation and depolymerisation stage is to minimise lignin condensation (i.e. formation of resistive carbon–carbon linkages). During fractionation, this can be achieved by either (i) preserving the (native) lignin structure or (ii) by tolerating depolymerisation of the lignin polymer but preventing condensation through chemical quenching or physical removal of reactive intermediates. The latter strategy is also commonly applied in the lignin depolymerisation stage, while an alternative approach is to augment the relative rate of depolymerisation vs. condensation by enhancing the reactivity of the lignin structure towards depolymerisation. Finally, because depolymerised lignins often consist of a complex mixture of various compounds, upgrading of the raw product mixture through convergent transformations embodies a promising approach to decrease the complexity. This particular upgrading approach is termed funneling, and includes both chemocatalytic and biological strategies.
1,466 citations
TL;DR: The various hemicelluloses structures present in lignocellulose, the range of pre-treatment and hydrolysis options including the enzymatic ones, and the role of different microbial strains on process integration aiming to reach a meaningful consolidated bioprocessing are reviewed.
1,355 citations
Cites background or methods from "Pretreatment and fractionation of c..."
...Again, selectivity is low, as delignification is high and can reach 60–85% (Kim et al., 2003, 2008; Kim and Lee, 2005)....
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...Cellulose fraction is almost not degraded (solubilisation <10%), but in the following cellulose hydrolysis step yields are close to the theoretical (Kim et al., 2000, 2008, 2003; Kim and Lee, 2005; Yoon et al., 1995)....
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...Ammonia recycling percolation (ARP) is carried out using aqueous ammonia in a flow-through mode at high temperatures (typically around 170 C) (Kim and Lee, 2005)....
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...ARP has already been successfully applied to hardwoods (Kim et al., 2008; Yoon et al., 1995) and corn stover (Kim et al., 2003, 2006; Kim and Lee, 2005; Zhu et al., 2006) with treated biomass presenting a cellulose digestibility above 93%, and with a slight less efficiency to wastepaper and…...
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References
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TL;DR: An empirical model was identified that describes the roles of lignin content, acetyl contents, and crystallinity indices in enzymatic hydrolysis and the digestibility of several lime-treated biomass samples agreed with the empirical model.
Abstract: Poplar wood was treated with peracetic acid, KOH, and ball milling to produce 147 model lignocelluloses with a broad spectrum of lignin contents, acetyl contents, and crystallinity indices (CrIs), respectively. An empirical model was identified that describes the roles of these three properties in enzymatic hydrolysis. Lignin content and CrI have the greatest impact on biomass digestibility, whereas acetyl content has a minor impact. The digestibility of several lime-treated biomass samples agreed with the empirical model. Lime treatment removes all acetyl groups and a moderate amount of lignin and increases CrI slightly; lignin removal is the dominant benefit from lime treatment.
1,259 citations
TL;DR: Corn stover was pretreated with aqueous ammonia in a flow-through column reactor, a process termed ammonia recycled percolation (ARP), and the enzymatic digestibility was related with the removal of lignin and hemicellulose, perhaps due to increased surface area and porosity.
603 citations
TL;DR: In this paper, the lignin content and initial pore volume of Douglas fir pulps, a refiner mechanical pulp (RMP), sulphonated RMP, delignified RMP and a kraft pulp were compared on the basis of lignins content.
458 citations
01 Jan 1976
161 citations
TL;DR: Three recycling strategies were evaluated to determine their efficiencies over five successive rounds of hydrolysis and, in all three of the recycling strategies, lower cellulase activities were recovered from the substrates with higher lignin contents.
Abstract: Recycling of cellulases should lower the overall cost of lignocellulosiic bioconversion processes. In this study, three recycling strategies were evaluated to determine their efficiencies over five successive rounds of hydrolysis. The effect of lignin on recycling was examined by comparing water-washed, steam-exploded birch (WB; 32% lignin) and WB which had been further extracted with alkali and peroxide (PB; 4% lignin). When the cellulases were recovered from the residual substrates after partial hydrolysis of both substrates, the recovered cellulase activity toward the mixture of fresh and residual substrates decreased after each recycling step. When the cellulases in the supernatants were also recycled, up to 20% more activity could be recovered. In both of these cases, the recovered activities did not correspond to the activities expected from the amount of cellulase protein recovered during recycling. The best recovery was obtained when the cellulases were recovered from both the residue and the supernatant after complete hydrolysis of the PB substrate. In this case, all of the originally added cellulase activity could be recovered for four consecutive hydrolysis rounds. However, when the same recycling strategy was carried out using the WB substrate, the recovered cellulase activity declined quickly with each recycling round. In all three of the recycling strategies, lower cellulase activities were recovered from the substrates with higher lignin contents. (c) 1995 John Wiley & Sons, Inc.
160 citations