Lignin transformations for high value applications: towards targeted modifications using green chemistry

Gillet, Sébastien; Aguedo, Mário; Petitjean, L.; Morais, Ana Rita C.; Lopes, André M. da Costa; Bogel‐Łukasik, Rafał; Anastas, Paul T.

doi:10.1039/c7gc01479a

Cited by 559 publications

(399 citation statements)

References 249 publications

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“…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 A); 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 B); 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 C) . It is becoming evident that for any lignin application, discrete regions of the bulk molecular weight distribution (MWD) will be most suitable ,. For example, low molecular weight (MW) Kraft lignin fractions were shown to form thermosets with more optimal properties .…”

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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Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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“…However, the global reserve scarcity and the exorbitant price of noble metals limit their extensive usage. Non‐noble metal catalysts are normally based on Fe, Co, Cu, and especially Ni, which are considered to be desirable replacements of noble metal catalysts because of their abundant reserves, low cost, and moderate activity . Nickel‐based catalysts have shown excellent chemoselectivity for aromatic products or high activity for C—O bond cleavage .…”

Section: Introductionmentioning

confidence: 99%

Comparison of Kinetics and Activity of Ni‐Based Catalysts for Benzyl Phenyl Ether Catalytic Hydrogenolysis

et al. 2019

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The influence of the type of support [activated carbon (AC), HZSM‐5, and γ‐Al2O3] on the performance of Ni‐based catalysts for the catalytic hydrogenolysis (CH) of benzyl phenyl ether (BPE) is investigated. The properties of an Ni‐based catalyst are investigated using diverse characterization techniques. An Ni/AC catalyst exhibits the highest dispersion of Ni atoms by CO pulse. The kinetic studies show that the apparent activation energies (Ea) for CH of BPE increase in the order Ea (Ni/AC) < Ea (Ni/γ‐Al2O3) < Ea (Ni/HZSM‐5), and the initial turnover frequencies follow the order of Ni/AC (64 mol molNisurf −1 h−1) > Ni/γ‐Al2O3 (58 mol molNisurf −1 h−1) > Ni/HZSM‐5 (45 mol molNisurf −1 h−1). All these results prove that the CH activity of BPE is significantly affected by the type of support, and Ni/AC is the highest activity catalyst in CH of the C—O bond of BPE. Toluene and phenol are major products in CH of BPE at a relatively low hydrogen pressure and high temperature. Based on catalytic experiments, a reaction mechanism is proposed, which provides the theoretical basis for converting lignite into high‐value organic molecules.

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“…Another popular lignin depolymerization strategy involves the utilization of base to carry out the fragmentation and separation of different monomers …”

Section: Introductionmentioning

confidence: 99%

Attapulgite‐supported magnetic dual acid–base catalyst for the catalytic conversion of lignin to phenolic monomers

Zhang

Zhao

et al. 2019

J of Chemical Tech & Biotech

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BACKGROUND Research on the catalytic conversion of lignin into value‐added chemicals has grown rapidly on account of the importance of lignin in the biorefinery. There is thus a need to investigate novel technologies to depolymerize lignin in the absence of hydrogen gas and noble metal catalysts. This study developed a cheap and recyclable catalyst via a facile process involving impregnation and calcination for the conversion of lignin to value‐added phenolic monomers. RESULTS Acid sites, basic sites and magnetic components were successfully incorporated into attapulgite. The resulting catalyst displayed high catalytic activity for lignin conversion to phenolic monomers, which resulted in 10.9% total monomers yield at 250 °C for 3 h with a catalyst loading of 50% and a solvent–solid ratio of 20:1 in 50% C2H5OH. The total monomers yield decreased observably after eight successive reaction runs. After being calcined at 600 °C for 3 h, the recovered catalyst provided a total monomers yield of 6.74% in the ninth reaction run. CONCLUSION A novel catalyst was successfully prepared by incorporation of acid sites, basic sites and magnetic properties using natural attapulgite clay as a precursor via a simple and inexpensive process. The resulting catalyst could depolymerize lignin efficaciously. The reusability of the catalyst was barely satisfactory, however, the activity could be partly recovered by simple calcination. © 2018 Society of Chemical Industry

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Lignin transformations for high value applications: towards targeted modifications using green chemistry

Abstract: We provide a critical review of green processes enabling the fractionation and/or depolymerization of lignin towards value-added products.

Cited by 559 publications

References 249 publications

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

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

Comparison of Kinetics and Activity of Ni‐Based Catalysts for Benzyl Phenyl Ether Catalytic Hydrogenolysis

Attapulgite‐supported magnetic dual acid–base catalyst for the catalytic conversion of lignin to phenolic monomers

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