Influence of Base-Catalyzed Organosolv Fractionation of Larch Wood Sawdust on Fraction Yields and Lignin Properties (original) (raw)
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The development of biomass pretreatment approaches that, next to (hemi)cellulose valorization, aim at the conversion of lignin to chemicals is essential for the long-term success of a biorefinery. Herein, we discuss a dithionite-assisted organosolv fractionation (DAOF) of lignocellulose in nbutanol and water to produce cellulosic pulp and mono-/oligo-aromatics. The present study frames the technicalities of this biorefinery process and relates them to the features of the obtained product streams. Via the extensive characterization of the solid pulp (by acid hydrolysis-HPLC, ATR-FTIR, XRD, SEM and enzymatic hydrolysis-HPLC), of lignin derivatives (by GPC, GC-MS/FID, 1 H-13 C HSQC NMR, and ICP-AES) and of carbohydrate derivatives (by HPLC) we comprehensively identify and quantify the different products of interest. These results were used for inspecting the economic feasibility of DAOF. The adoption of a dithionite loading of 16.7% w/wbiomass and of an equivolumetric mixture of n-butanol and water, which led to a high yield of monophenolics (~20%, based on acid insoluble lignin, for the treatment of birch sawdust), was identified as the most profitable process configuration. Furthermore, the treatment of various lignocellulosic feedstocks was explored, which showed that DAOF is particularly effective for processing hardwood and herbaceous biomass. Overall, this study provides a comprehensive view of the development of an effective dithionite-assisted organosolv fractionation method for the sustainable upgrading of lignocellulosic biomass.
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Over the years, the organosolv pulping process has proven to be a valuable pretreatment method for various lignocellulosic feedstocks. The objective of this study was to characterize and assess the potential applicability of the organosolv lignin fraction from European larch sawdust, as no research has been conducted in this field so far. Eight different samples were prepared from the European larch sawdust under varied reaction conditions and one milled wood lignin sample as reference. The reaction temperature and sulfuric acid loading were varied between 420 and 460 K and 0.00 and 1.10% (w/w on dry wood basis) H2SO4, respectively. The antiradical potential (via DPPH• method), chemical structure (via ATR-FTIR, 1H NMR, 31P NMR, and thioacidolysis), as well as the molecular weight distribution of the isolated lignins were analyzed and compared. Results from thioacidolysis show a direct correlation between the amount of β-ether bonds broken and pulping process severity. Similarly, bot...
Canadian Journal of Chemical Engineering, 1993
A prototype hardwood Populus deltoids has been fractionated in kg quantities into its primary constitutive polymers, namely, cellulose, hemicelluloses, and lignin, under optimal recovery conditions for each fraction.Our approach is targeted at processing sawdust or finally divided wood (dp ≤ 0.5 mm) and involves a thermomechano-solvolytic treatment of medium consistency suspensions in two process development units operated sequentially. Firstly, the hemicellulose fraction is removed from the initial wood by a aqueous-steam pretreatment (auto-hydrolysis) at conditions where nearly 90% of the hemicelluloses are solubilized. Secondly, the treated wood (lignocellulose) is separated into cellulose and lignin rich fractions by subjecting it to an organosolvolytic treatment using ethylene glycol as solvent. An experimental unit which can be operated in semi-continuous or continuous modes is described and was employed for this step. The recovery of each fraction via appropriate mass balances is presented.Also, a comparative characterization of the lignins isolated via (a) the direct solvolysis route and (b) the sequential aqueous-steam pretreatment followed by solvolysis approach is made using solvent fractionation, molar mass distribution, and 13C NMR spectroscopy methods.Un échantillon de bois dur Populus deltoids a été fractionné en ses polymères constitutifs principaux, à savoir la cellulose, l'hémicellulose et la lignine (quantités exprimées en kg), dans des conditions de récupération optimales pour chaque fraction.Le but de notre approche est de traiter la sciure ou les résidus de bois (dp ≤ 0,5 mm). Elle est basée sur un traitement thermomécano-solvolytique des suspensions de consistance moyenne dans deux unités de développement de procédés fonctionnant en mode séquentiel. Dans un premier temps la fraction d'hémicellulose est extraite du bois initial par un prétraitement à la vapeur (autohydrolyse) dans des conditions permettant la solubilisation de près de 90% de l'hémicellulose. Par la suite, on sépare le bois traité (lignocellulose) en fractions riches en lignine et en cellulose en lui faisant subir un traitement organosolvolytique avec de l'éthylène glycol comme solvant. Une unité expérimental fonctionnant soit en mode semi-continu ou continu est décrite et a été employée pour cette étape. On décrit la récupération de chaque fraction à l'aide des bilans massiques.En outre, on a effectué une caractérisation comparative des lignines isolées, d'une part, par la voie solvolytique directe et, d'autre part, par le prétraitement à la vapeur suivi d'une solvolyse en ayant recours au fractionnement par solvant, à la distribution de masse molaire et à la spectrométrie 13C NMR.
The development of biomass pretreatment approaches that, next to (hemi)cellulose valorization, aim at the conversion of lignin to chemicals is essential for the long-term success of a biorefinery. Herein, we discuss a dithionite-assisted organosolv fractionation (DAOF) of lignocellulose in n-butanol and water to produce cellulosic pulp and mono-/oligo-aromatics. The present study frames the technicalities of this biorefinery process and relates them to the features of the obtained product streams. Via the extensive characterization of the solid pulp (by acid hydrolysis-HPLC, ATR-FTIR, XRD, SEM and enzymatic hydrolysis-HPLC), of lignin derivatives (by GPC, GC-MS/FID, 1H-13C HSQC NMR, and ICP-AES) and of carbohydrate derivatives (by HPLC) we comprehensively identify and quantify the different products of interest. These results were used for inspecting the economic feasibility of DAOF. The adoption of a dithionite loading of 16.7% w/wbiomass and of an equivolumetric mixture of n-butan...
Canadian Journal of Chemistry-revue Canadienne De Chimie, 1993
. Thermal organosolv glycol lignins and their fractions have been characterized by means of elemental composition, molecular weight distribution, and 'H and I3c NMR spectroscopy. Fractionation of each lignin by sequential solvent extraction produced fractions of increasing molecular weight and polydispersity. Structures in the highest molecular weight fractions were found to be linked by a high proportion of P-0-4 type bonds, whilst the lowest molecular weight fractions consisted of a high content of saturated aliphatic side-chain structures. A noticeable difference in the content of carbohydrate contaminants in both starting lignins indicated the formation of relatively stable lignin-carbohydrate complexes, especially in the lignin recovered from pretreated wood. In addition, depolymerization of the lignins and their fractions to monomeric compounds was explored using alkaline hydrolytic and nitrobenzene oxidative routes. The highest molecular weight fractions from each lignin were identified as the best candidates for production of useful monomeric phenolic compounds. RONALD W. THRING, ESTEBAN CHORNET et RALPH P. OVEREND. Can. J . Chem. 71, 779 (1993). En se basant sur la composition ClCmentaire, la distribution des poids molCculaires et la RMN du 'H et du I3c, on a caractCrisC les lignines thermiques de l'organosolv glycol et leurs fractions. Le fractionnement de chaque lignine par extraction ~Cquentielle par les solvants a fourni des fractions de poids molCculaires et de polydispersitCs croissants. On a trouvC que les structures des fractions de poids molCculaires les plus ClevCs sont likes en grande partie par des liaisons de type P-0-4 alors que celles des fractions de poids molCculaires plus faibles comportent de grandes quantites de chaines laterales aliphatiques saturkes. On a not6 une difference notablehans le contenuen hydrates de carbone des deux lignines; elle indique qu'il y a formation de complexes ligninehydrate de carbone relativement stables, particulikrement dans la lignine rCcupCrCe du bois prCtraitC. On a de plus examine la dCpolymCrisation des lignines et de leurs fractions en composCs monomeres par hydrolyse alcaline et par oxydation avec du nitrobenzkne. Pour la production de composCs phCnoliques monomkres utiles, on a identifiC que les fractions de poids molCculaires les plus ClevCs de chacune des lignines seraient les plus appropriCes. [Traduit par la rCdaction]
Diol pretreatment to fractionate a reactive lignin in lignocellulosic biomass biorefineries
Green Chemistry, 2019
Lignin-first fractionation has become a new biorefinery target to obtain valuable lignin monomers toward the complete utilization of lignocellulosic biomass, but increasing delignification through conventional pretreatment approaches often affects the structural integrity of the dissociated lignin. We discovered a new reactive lignin with a great solvent solubility and preserved β-O-4 linkages from eucalyptus after a modified organosolv pretreatment using 1,4-butanediol (1,4-BDO). Unlike conventional organosolv pre-treatment using ethanol, lignin deposition was not observed in 1,4-BDO pretreatment. Meanwhile, 2D HSQC NMR analysis revealed that the residual lignin obtained from 1,4-BDO pretreated eucalypts contained a relatively higher amount of β-O-4 interunit linkages, indicating its higher integrity than ethanol pretreated lignin. This result agreed with the lower content of phenolic hydroxyl groups in dissolved lignin via 31 P NMR analysis. With increasing pretreatment severity, the amount of aliphatic hydroxyl groups decreased in ethanol pretreated lignin while it remained at a higher level in 1,4-BDO pretreated lignin. These results suggested that 1,4-BDO quenched the benzyl carbocation intermediate and formed ether linkages with a hydroxyl tail at the α position of the lignin. Solubility tests revealed that grafting aliphatic hydroxyl groups on 1,4-BDO lignin increased its dissolution. This phenomenon was further demonstrated for four different diols with similar structures. In addition, more than 90% cellulose conversion was obtained for all the diol pretreated eucalyptus after 48 h of enzymatic hydrolysis with cellulase at a loading of 7.5 FPU per gram of glucan. Diol pretreatment thus offers a promising reaction pathway to coincide with three pillars of biorefinery for lignin fractionation, lignin structural integrity, and cellulose hydrolysis.
Thermal-Chemical Fractionation of Lignocellulosic Biomass
2019
Biomass is a valuable, sustainable feedstock for the production of chemicals and materials, and will play an important role in the transition towards a Sustainable Process Industry. Bio-based products – products wholly or partly derived from materials of biological origin – can make the society more sustainable and lower its dependence on fossil fuels. For the optimal utilization of bio-resources, fractionation on the basis of functionalities is often desired. Most commonly, biomass is separated into its main constituents lignin, cellulose and hemi-cellulose by steam or acid treatment. Thermochemical fractionation is an alternative, innovative two-step conversion process to transform different bio-resources into rawmaterials for renewable chemicals and products. In this approach, a short thermal treatment at elevated temperature (fast pyrolysis) is followed by a low temperature fractionation of the mineral free, liquid product (FPBO) that keeps the key chemical functionalities intac...