Degradation of lignin catalyzed by nanochannels solid acids in ionic liquid

Kang, Senxian; Bu, Daqin; Xue, Liyuan; Wang, Qi; Jiang, Man

doi:10.1016/j.polymdegradstab.2019.05.015

Cited by 12 publications

(3 citation statements)

References 33 publications

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“…Besides the homogeneous acid catalysts discussed above, heterogeneous acid catalysts are also widely used in lignin acidolysis or fast pyrolysis. For these solid acid catalysts, they can be liquid acids immobilized on various supports to form immobilized liquid acids − or just as the forms of metal oxides, − zeolites, − and polyoxometalate salts with low solubility, etc.…”

Section: Cationic Intermediatesmentioning

confidence: 99%

Catalytic Strategies and Mechanism Analysis Orbiting the Center of Critical Intermediates in Lignin Depolymerization

et al. 2023

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Lignin, as a precious resource given to mankind by nature with abundant functional aromatic structures, has drawn much attention in the recent decade from academia to industry worldwide, aiming at harvesting aromatic compounds from this abundant and renewable natural polymer resource. How to efficiently depolymerize lignin to easy-to-handle aromatic monomers is the precondition of lignin utilization. Many strategies/methods have been developed to effectively degrade lignin into monomers, such as the traditional methods of pyrolysis, gasification, liquid-phase reforming, solvolysis, chemical oxidation, hydrogenation, reduction, acidolysis, alkaline hydrolysis, alcoholysis, as well as the newly developed redox-neutral process, biocatalysis, and combinatorial strategies. Therefore, there is a strong demand to systemically summarize these developed strategies and methods and reveal the internal transformation principles of the lignin. Focusing on the topic of lignin depolymerization to aromatic chemicals, this review reorganizes and categorizes the strategies/methods according to their mechanisms, orbiting the center of critical intermediates during the lignin linkage transformation, which includes the critical anionic intermediates, cationic intermediates, organometallic intermediates, organic molecular intermediates, aryl cation radical intermediates, and neutral radical intermediates. The corresponding introduction involves the generation and the transformation chemistry of the critical intermediates via the corresponding C–H/O–H/C–C/C–O chemical bond transformations, leading to the cleavage of the C–C/C–O linkage bonds. Accompanying the brief introduction of lignin chemistry and the final concluding remarks and perspectives on lignin depolymerization, this review aims to provide a current research process of lignin depolymerization, which may provide useful suggestions for this vigorous research field.

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Section: Cationic Intermediatesmentioning

confidence: 99%

Catalytic Strategies and Mechanism Analysis Orbiting the Center of Critical Intermediates in Lignin Depolymerization

et al. 2023

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“…Lignin is a renewable resource with the highest content of benzene rings in nature, and it is also the most abundant phenolic compound, so it has the prospect of being converted into aromatic monomer chemicals. At present, how to effectively degrade lignin into small molecular compounds is one of the most popular works [7].…”

Section: Introductionmentioning

confidence: 99%

Degradation of Alkaline Lignin in the Lactic Acid-Choline Chloride System under Mild Conditions

Li¹,

Jiang²,

Chen³

et al. 2023

Journal of Renewable Materials

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Lignin is a natural polymer, second only to cellulose in natural reserves. Degradation is one of the ways to achieve the high-value transformation of lignin. Deep eutectic solvent (DES) thermal degradation of lignin can be used as an excellent green degradation method. This paper introduces the degradation mechanism and effect of the lactic acid-choline chloride DES system in dissolving and degrading alkaline lignin, and the final solvent recovery. It can also be found from the scanning electron microscope (SEM) images that the surface of the degraded solid product is transformed from smooth to disordered. Fourier transform infrared (FTIR) spectroscopy and 1 H-NMR spectroscopy were used to characterize the changes in lignin functional groups during DES treatment. The results showed that the content of phenolic hydroxyl groups increased after degradation, indicating that the β-O-4 ether bond was broken. The molecular weight of the degraded lignin was observed by gel permeation chromatography (GPC), and the lignin residue with low molecular weight and narrow polydispersity index was obtained. The lowest average molecular weight (Mw) reached 2512 g/mol. The ratio of oxygen to carbon atoms in lignin increased substantially during degradation as measured by X-ray photoelectron spectroscopy (XPS), probably because DES treatment was accompanied by many oxidation reactions, which led to significant structural changes in lignin and a large number of ether bond breakage reactions during the reaction. The main final degradation products are aromatic monomers, vanillin, butyrovanillone, etc.

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“…To this end, the benzyl phenyl ether was converted into toluene and phenol, in addition to cyclohexanol from the exhaustive reduction of phenol. Despite significant advances in the field of transfer hydrogenolytic cleavage of C-O bonds, most hydrogenolysis reactions either require high-pressure hydrogen gas or reductive organic molecules (such as alcohols and formic acid) as hydrogen donors (Hanson et al, 2010 ; Zhang et al, 2012 ; Rahimi et al, 2014 ; Díaz-Urrutia et al, 2016 ; Gomez-Monedero et al, 2017 ; Wang et al, 2017 ; Rinesch and Bolm, 2018 ; Kang et al, 2019 ; Liu et al, 2019 ; Yang et al, 2019 ). Nevertheless, hydrogen is challenging to handle and use under very high pressures and organic solvents are expensive and very often not environmentally friendly.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Cleavage of the C-O Bond in 2,6-dimethoxyphenol Without External Hydrogen or Organic Solvent Using Catalytic Vanadium Metal

Xie

Tan

et al. 2020

Front. Chem.

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Hydrogenolysis of the CO bonds in lignin, which promises to be able to generate fuels and chemical feedstocks from biomass, is a particularly challenging and important area of investigation. Herein, we demonstrate a vanadium-catalyzed cleavage of a lignin model compound (2,6-dimethoxyphenol). The impact of the catalyst in the context of the temperature, reaction time, and the solvent, was examined for the cleavage of the methyl ethers in 2,6-dimethoxyphenol. In contrast to traditional catalytic transfer hydrogenolysis, which requires high pressure hydrogen gas or reductive organic molecules, such as an alcohol and formic acid, the vanadium catalyst demonstrates superior catalytic activity on the cleavage of the CO bonds using water as a solvent. For example, the conversion of 2,6-dimethoxyphenol is 89.5% at 280 • C after 48 h using distilled water. Notably, the vanadium-catalyzed cleavage of the CO bond linkage in 2,6-dimethoxyphenol affords 3-methoxycatechol, which undergoes further cleavage to afford pyrogallol. This work is expected to provide an alternative method for the hydrogenolysis of lignin and related compounds into valuable chemicals in the absence of external hydrogen and organic solvents.

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Degradation of lignin catalyzed by nanochannels solid acids in ionic liquid

Cited by 12 publications

References 33 publications

Catalytic Strategies and Mechanism Analysis Orbiting the Center of Critical Intermediates in Lignin Depolymerization

Catalytic Strategies and Mechanism Analysis Orbiting the Center of Critical Intermediates in Lignin Depolymerization

Degradation of Alkaline Lignin in the Lactic Acid-Choline Chloride System under Mild Conditions

Catalytic Cleavage of the C-O Bond in 2,6-dimethoxyphenol Without External Hydrogen or Organic Solvent Using Catalytic Vanadium Metal

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