Reductive catalytic fractionation of lignocellulose: when should the catalyst meet depolymerized lignin fragments?

Qiu, Shi; Wang, Meng; Fang, Yunming; Tan, Tianwei

doi:10.1039/d0se01118e

Cited by 25 publications

(25 citation statements)

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“…The choice of the process temperature, duration and hydrogen pressure is based on the analysis of literature [11,19,24,28]. The results of experiments on hydrogenation of flax shive in ethanol without and with the different Ru/C catalysts are given in Table 4.…”

Section: Catalytic Hydrogenation Of Flax Shive In Ethanolmentioning

confidence: 99%

“…A presence of acid catalysts in the reaction mixture accelerate RCF process and results in lignin mononers yields increase due to acidolysis of ether bonds between phenylpropane units [18,19]. Our group previously studied supported ruthenium catalysts based on oxidized graphite-like carbon Sibunit ® -4 (containing acid surface species [20,21]) for lignin and wood conversion, and subsequently set out to identify lower cost, easily available, and highly efficient catalysts to enhance the efficiency of the lignin conversion process [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

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Reductive Catalytic Fractionation of Flax Shive over Ru/C Catalysts

et al. 2020

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Flax shive is the main waste (up to 70 wt %) in the production of flax fiber. It represents the lignified parts of the flax stem mainly in the form of small straws. Complex processing of such wastes is a significant problem due to the heterogeneity of the chemical structure of lignin. This article presents the results of reductive catalytic fractionation (RCF) of flax shive in ethanol and isopropanol at elevated temperatures (225–250 °C) in the presence of a bifunctional catalyst (Ru/C) and molecular hydrogen. This provides solvolytic depolymerization of lignin and hemicelluloses presented in flax shive. Catalytic hydrogenation effectively stabilizes the formed lignin intermediates and prevents repolymerization reactions producing the lignin fraction with a high degree of depolymerization. RCF of flax shive produces solid products with a high cellulose content and liquid products consisting mainly of monophenolic compounds. Furthermore, the effect of different characteristics (the ruthenium content, particle size, and support acidity) of the bifunctional catalysts containing ruthenium nanoparticles supported on mesoporous, graphite-like carbon material Sibunit®-4 on the yield and composition of the products of hydrogenation of flax shive in sub- and super-critical ethanol has been studied. Bifunctional catalysts Ru/C used in the RCF of flax shive increase its conversion from 44 to 56 wt % and the yield of monophenols from 1.1 to 10.2 wt % (based on the weight of lignin in the sample). Using the best Ru/C catalyst containing 3% of Ru on oxidized at 400 °C carbon support, the high degree of delignification (up to 79.0%), cellulose yield (up to 67.2 wt %), and monophenols yield (up to 9.5 wt %) have been obtained.

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Section: Catalytic Hydrogenation Of Flax Shive In Ethanolmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reductive Catalytic Fractionation of Flax Shive over Ru/C Catalysts

et al. 2020

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“…It is preferably operated in batch reactors under high pressures and temperatures in the range of 180-250 ºC [114], but researchers have already pointed out that other conditions can also be used. Qiu et al [115] suggest that the addition of catalysts should be carried out before the reactor temperature reaches 200 ºC to avoid lignin repolymerization problems. To simplify the execution of the RCF and mitigate its capital costs, Ren et al proposed the operation of the RCF under ambient pressure, which was called atmospheric RCF (ARCF) [116].…”

Section: Lignin Valorizationmentioning

confidence: 99%

Production and Application of Lignin-Based Chemicals and Materials in the Cellulosic Ethanol Production: An Overview on Lignin Closed-Loop Biorefinery Approaches

Padilha

Nogueira

Alencar

et al. 2021

Waste Biomass Valor

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Lignocellulosic biomass is the most abundant biological resource on the planet and has been extensively researched to produce cellulosic ethanol. However, there is a consensus that the presence of lignin hinders the biomass conversion. Lignin is often considered a villain in cellulosic ethanol production studies due to its adverse effects on cellulases and yeasts. Despite this, recent studies indicate that lignins can be transformed into useful inputs to produce cellulosic ethanol. These approaches aim to establish closed-loop biorefineries to improve economic metrics and reduce the environmental impact due to the substitution of products based on fossil sources. The present review addresses the successful cases in transforming lignin into chemicals and materials to increase cellulosic ethanol titers. A contextualization was first carried out, considering aspects of biomass characteristics and lignin valorization. The impact of lignin-based chemicals and materials in the pretreatment, detoxification, and enzymatic hydrolysis steps was discussed in detail. Economic aspects and future perspectives were also included in this review. These reports open a new point of view on lignin valorization and its integration with the cellulosic ethanol production chain.

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“…14,15 The resulting (hydroxy)alkenyl-substituted lignin moieties are ultimately stabilized against recondensation by the action of the redox catalyst, which promotes the hydrogenation of C�C bonds in their side chains. 14,16,17 The first studies on the catalytic hydrogenolysis and hydrogenation of woody biomass date back to the 1940s, when this method was employed as a means to explore the chemical structure of lignin. 18,19 At that time, the hydrogenation of wood was also proposed as a pulping method, 20,21 but it was only in the 2010s that the RCF concept took the spotlight as a means to develop integrated biorefineries.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Lignin represents the largest source of renewable aromatics available on Earth and, therefore, it is considered an alluring platform for the sustainable production of chemicals and materials. − Despite its inherent potential, the valorization of the lignin fractions produced by conventional biomass fractionation methods is hampered by the heterogeneity and the high degree of condensation of such technical lignins. − The incumbent need for more efficient strategies for lignin valorization fostered the development of a new class of methods that aim at the active stabilization of the lignin derivatives produced during biomass fractionation, thereby preventing lignin condensation. , Among these “lignin-first” approaches, the reductive catalytic fractionation (RCF) of lignocellulose is particularly promising, as it was demonstrated to effectively extract lignin from biomass and convert it toward valuable monophenolics with near-theoretical yields (based on the content of β-O-4 linkages in the lignin matrix) in a single step. , The RCF relies on the thermal treatment of lignocellulose in an organic solvent in the presence of a redox catalyst and a source of hydrogen. , Under these conditions, lignin is solubilized and labile lignin interunit bonds (mainly β-O-4 linkages) are cleaved via solvolysis and hydrogenolysis. , The resulting (hydroxy)alkenyl-substituted lignin moieties are ultimately stabilized against recondensation by the action of the redox catalyst, which promotes the hydrogenation of CC bonds in their side chains. ,, …”

Section: Introductionmentioning

confidence: 99%

Reductive Catalytic Fractionation of Wheat Straw Biomass

Brienza

Aelst

Devred

et al. 2022

ACS Sustainable Chem. Eng.

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The reductive catalytic fractionation (RCF) is a promising method for the development of "lignin-first" biorefineries. Apart from the widely investigated virgin woody biomass, it is essential to explore the potential of waste biomass feedstocks. Herein, the RCF of wheat straw is examined to produce lignin mono-/oligomers along with a processable carbohydrate pulp. The use of different catalysts (Ru/C and Ru/Al 2 O 3 ) and catalyst loadings (0−20% w/w biomass ) revealed the superior performance of Ru/C, which resulted in the largest yield of phenolic monomers (up to ∼25 wt % of initial acid-insoluble lignin) and in the lowest formation of high-molecular-weight fragments in the extracted lignin oil. Furthermore, the operating temperature was shown to substantially affect both lignin extraction−depolymerization and polysaccharides preservation−processability. For a reaction time of 3 h, an increase of the temperature from 200 to 250 °C resulted in a >2-fold boost of the yields of lignin oil and monophenolics, while the recovery of polysaccharides decreased by about 30 wt % (with ∼20% lower enzymatic digestibility). An economic assessment highlighted that the high-temperature treatment becomes the most profitable configuration as the market price of lignin products increases. Overall, this work provides insight into the adoption of the RCF for the upgrading of lignocellulose from inexpensive and widely available wheat straw biomass.

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Reductive catalytic fractionation of lignocellulose: when should the catalyst meet depolymerized lignin fragments?

Abstract: Reductive catalytic fractionation (RCF) is a promising lignin-first biorefinery strategy which yields a deeply depolymerized lignin and nearly theoretical amounts of lignin monomers with reductive catalysts. The immediate stabilization with...

Cited by 25 publications

References 50 publications

Reductive Catalytic Fractionation of Flax Shive over Ru/C Catalysts

Reductive Catalytic Fractionation of Flax Shive over Ru/C Catalysts

Production and Application of Lignin-Based Chemicals and Materials in the Cellulosic Ethanol Production: An Overview on Lignin Closed-Loop Biorefinery Approaches

Reductive Catalytic Fractionation of Wheat Straw Biomass

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