Identification of a diagnostic structural motif reveals a new reaction intermediate and condensation pathway in kraft lignin formation

Lancefield, Christopher S.; Wienk, Hans; Boelens, Rolf; Weckhuysen, Bert M.; Bruijnincx, Pieter C. A.

doi:10.1039/c8sc02000k

Cited by 178 publications

(219 citation statements)

References 88 publications

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“…Stilbenoid units (SB1 and SB5) were additionally included in this analysis, as we have recently identified them as particularly abundant units in softwood kraft lignin. [12,46] The improved correlation resultss uggested that the models shouldb ea ble to predict the properties of new,l ignin samples obtained independently from the original calibration set with reasonably high accuracy. This is demonstrated by the analysiso favalidation set of lignins.…”

Section: Resultsmentioning

confidence: 96%

“…Using the previously determined optimal method for processing the IR spectra, this focused set of lignins produced significantly improved results with higher R 2 Cal., R 2 CV and lower REs for the PLS models (Table ). Stilbenoid units (SB1 and SB5) were additionally included in this analysis, as we have recently identified them as particularly abundant units in softwood kraft lignin . The improved correlation results suggested that the models should be able to predict the properties of new, lignin samples obtained independently from the original calibration set with reasonably high accuracy.…”

Section: Resultsmentioning

confidence: 99%

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Linkage Abundance and Molecular Weight Characteristics of Technical Lignins by Attenuated Total Reflection‐FTIR Spectroscopy Combined with Multivariate Analysis

Lancefield

Constant

Peinder³

et al. 2019

ChemSusChem

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Lignin is an attractive material for the production of renewable chemicals, materials and energy. However, utilization is hampered by its highly complex and variable chemical structure, which requires an extensive suite of analytical instruments to characterize. Here, we demonstrate that straightforward attenuated total reflection (ATR)‐FTIR analysis combined with principle component analysis (PCA) and partial least squares (PLS) modelling can provide remarkable insight into the structure of technical lignins, giving quantitative results that are comparable to standard gel‐permeation chromatography (GPC) and 2D heteronuclear single quantum coherence (HSQC) NMR methods. First, a calibration set of 54 different technical (fractionated) lignin samples, covering kraft, soda and organosolv processes, were prepared and analyzed using traditional GPC and NMR methods, as well as by readily accessible ATR‐FTIR spectroscopy. PLS models correlating the ATR‐FTIR spectra of the broad set of lignins with GPC and NMR measurements were found to have excellent coefficients of determination ( R 2 Cal.>0.85) for molecular weight ( M n , M w ) and inter‐unit abundances (β‐ O ‐4, β‐5 and β‐β), with low relative errors (6.2–14 %) as estimated from cross‐validation results. PLS analysis of a second set of 28 samples containing exclusively (fractionated) kraft lignins showed further improved prediction ability, with relative errors of 3.8–13 %, and the resulting model could predict the structural characteristics of an independent validation set of lignins with good accuracy. The results highlight the potential utility of this methodology for streamlining and expediting the often complex and time consuming technical lignin characterization process.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Linkage Abundance and Molecular Weight Characteristics of Technical Lignins by Attenuated Total Reflection‐FTIR Spectroscopy Combined with Multivariate Analysis

Lancefield

Constant

Peinder³

et al. 2019

ChemSusChem

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“…In recent years, apart from its combustion for energy, isolation of lignin originating from industrial kraft pulping processes as well as biorefinery plants producing ethanol as biofuel has seen a steady increase. Parallel to the surge in the availability of lignin, nano‐ and microscaled lignin‐based materials and state‐of‐the‐art analytical techniques that provide a more detailed understanding of the structural differences of the various lignins were developed …”

Section: Introductionmentioning

confidence: 99%

Lignin for Nano‐ and Microscaled Carrier Systems: Applications, Trends, and Challenges

et al. 2019

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To liberate society from its dependence on fossil‐based fuels and materials it is pivotal to explore components of renewable plant biomass in applications that benefit from their intrinsic biodegradability, safety, and sustainability. Lignin, a byproduct of the pulp and paper industry, is a plausible material for carrying various types of cargo in small‐ and large‐scale applications. Herein, possibilities and constraints regarding the physical–chemical properties of the lignin source as well as modifications and processing required to render lignins suitable for the loading and release of pesticides, pharmaceuticals, and biological macromolecules is reviewed. In addition, the technical challenges, regulatory and toxicological aspects, and future research needed to realize some of the promises that nano‐ and microscaled lignin materials hold for a sustainable future are critically discussed.

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“…[1,2] However, the valorization of lignin remains a challenge due to its complex structure. [3][4][5][6][7][8][9] Its inherent heterogeneity is a result of at least three contributing factors: i) Lignin is made up of variable amounts of 3 possible C9 monomers (H, G, and S, Figure 1A); ii) different types of linkages are formed by coupling of the C9 monomers, the most abundant of which is the β-O-4 linkage ( Figure 1B); iii) Lignin has considerably higher variation in chain lengths compared to standard polymers leading to a high polydispersity (2.0-9.0 depending on the source and pretreatment method used, Figure 1C). [10] It is becoming evident that for any lignin application, discrete regions of the bulk molecular weight distribution (MWD) will be most suitable.…”

Section: Introductionmentioning

confidence: 99%

Using Fractionation and Diffusion Ordered Spectroscopy to Study Lignin Molecular Weight.

et al. 2019

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Recent reports demonstrate that applications of the biopolymer lignin can be helped by the use of a fraction of the lignin which has an optimal molecular weight range. Unfortunately, the current methods used to determine lignin's molecular weight are inconsistent or not widely accessible. Here, an approach that relies on 2D DOSY NMR analysis is described that provides a measure of lignin's molecular weight. Consistent results were obtained using this well‐established NMR technique across a range of lignins.

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Identification of a diagnostic structural motif reveals a new reaction intermediate and condensation pathway in kraft lignin formation

Abstract: Detailed structural analysis of industrial and model kraft lignins reveals an important new reaction intermediate and condensation pathway operating during kraft pulping.

Cited by 178 publications

References 88 publications

Linkage Abundance and Molecular Weight Characteristics of Technical Lignins by Attenuated Total Reflection‐FTIR Spectroscopy Combined with Multivariate Analysis

Linkage Abundance and Molecular Weight Characteristics of Technical Lignins by Attenuated Total Reflection‐FTIR Spectroscopy Combined with Multivariate Analysis

Lignin for Nano‐ and Microscaled Carrier Systems: Applications, Trends, and Challenges

Using Fractionation and Diffusion Ordered Spectroscopy to Study Lignin Molecular Weight.

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