Liquefaction Mechanism of β-O-4 Lignin Model Compound in the Presence of Phenol under Acid Catalysis. Part 1. Identification of the Reaction Products

Lin, Lianzhen; Yao, Yuanyong; Shiraishi, Nobuo

doi:10.1515/hf.2001.101

Cited by 72 publications

(45 citation statements)

References 21 publications

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“…Similar decomposition was observed for liquefaction with microwave power of 500 W at the initial liquefaction stage but with remarkable enhancement of reaction kinetics. The conversion yield showed a slight decrease from 105 to 150°C, which was attributed to the recondensation of the liquefaction intermediates (Lin et al 2001;Chen and Lu 2009). Accordingly, taking reaction efficiency and energy consumption into consideration, the optimal reaction temperature was 120°C and optimal microwave power was 300 W.…”

Section: Resultsmentioning

confidence: 99%

Optimization for microwave-assisted direct liquefaction of bamboo residue in glycerol/methanol mixtures

Xie

Hse

et al. 2015

J. For. Res.

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Bamboo residues were liquefied in a mixture of glycerol and methanol in the presence of sulfuric acid using microwave energy. We investigated the effects of liquefaction conditions, including glycerol/methanol ratio, liquefaction temperature, and reaction time on the conversion yield. The optimal liquefaction conditions were under the temperature of 120°C, the reaction time of 7 min, the glycerol-methanol-bamboo ratio of 8/0/2 (W/W), and the microwave power of 300 W. Maximum conversion yield was 96.7 %. The liquid products were separated into two contents (water soluble part and precipitate part) by addition of a sufficient amount of water. By Fourier transform infrared (FT-IR), the water soluble content mainly contained glycerol and its derivate and carbohydrate degradation products, and the precipitate content was mainly lignin derivatives.

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Section: Resultsmentioning

confidence: 99%

Optimization for microwave-assisted direct liquefaction of bamboo residue in glycerol/methanol mixtures

Xie

Hse

et al. 2015

J. For. Res.

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“…The formation of condensed residues may be correlated with the mutual reaction between degraded compounds from lignin and cellulose, resulting from the lack of a liquefying reagent in the liquefaction system (Kobayashi et al, 2004). Although the reaction processes of guaiacylglycerol-β-guaiacyl ether (GG) and cellobiose as model compounds of natural lignin and cellulose have been studied separately at the early stage of liquefaction reactions (Lin et al, 1997a, b, c;2001a, it should be noted that a shortage of studies on the liquefaction mechanism at different time intervals, especially on polycondensation mechanism with phenols/polyhydric alcohols at a later stage of acid catalyzed liquefaction of lignocellulose, may still be a major reason why liquefaction techniques have not been industrialized on a large scale and why liquefaction products have not yet been utilized widely. Hence, studying the polycondensation process and mechanism in the presence of phenols/polyhydric alcohols and acid catalysts is necessary to enrich basic research of lignocellulosic liquefaction.…”

Section: Introductionmentioning

confidence: 99%

Polycondensation reaction and its mechanism during lignocellulosic liquefaction by an acid catalyst: a review

2011

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The increase in the residue content resulting from polycondensation would be adverse to the utilization of lignocellulose and to the quality of products obtained from liquefi ed lignocellulosic material. The yield of the residue formed from liquefaction and the mechanism of polycondensation were reported mainly by Lin, Yamada and Kobayashi. The major products of cellulosic liquefaction are levulinic acid and hydroxymethylfurfural (HMF) derivatives under polyhydric alcohols and phenolated compounds under phenols. The cleavage of the β-O-4 bonds is the major reaction pathway of lignin liquefaction under various liquefying reagents regardless of whether they contain acid catalysts or not. The break up compounds by decomposition are polymerized to substances with high molecular weight by polycondensation in lignocellulosic liquefaction. The molecular weight of condensed residues increases almost linearly as a function of liquefaction time at the later stage of lignocellulosic liquefaction. The longer the time required, the greater the content of new residue generated by polycondensation during the entire process of liquefaction. We conclude that the condensed residues may stem from the interaction of degraded lignin and cellulose components in wood or from the products of two major components reacting with liquefying reagents.

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“…Lin used GG (guaiacylglycerol-β-guaiacyl), as a lignin model compound, carried out the relevant researches about liquefaction reaction mechanism of lignin compounds in the presence of sulfuric acidic catalyst [2,3] and without catalysts [4,5]. They had also attempted to clarify the reaction mechanism of cellulose with phenol under the acid-catalyzed conditions.…”

Section: Introductionmentioning

confidence: 99%

Characterization of liquefied products from model woody components in the presence of mineral acid catalysts

Wang

Chen

Apaer

et al. 2011

WIT Transactions on Ecology and the Environment

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Cellulose and lignin are the main structural polymers in the plant cell wall. Cellulose is the structural component of the primary cell wall of green plants, many forms of algae and the oomycetes. About 40-50% of woody matter is cellulose. Lignin is a highly cross-linked polymer created by the polymerization of substituted phenolic compounds, known as monolignols, such as coniferyl, pcoumaryl, and synapyl alcohol. Liquefaction process is one of the promising techniques for effective utilization of woody biomass for the lignocelluloses can be converted to liquid reactive materials as the bio-based materials. Cellulose would have an advantage of providing liquefied product with small range of variance. The phenolated woody components have high acidity in the presence of mineral acid catalysts and possess the constituents which can react with formaldehyde. In addition, lignin, one of the major woody components including the hydroxyl-benzyl structure, has the potential to react with formaldehyde. However, as its complexity in structure, the liquefaction mechanism and the liquefied products with phenol should be found out to solve some problems such as the reaction efficiency and low molecular weight products, and it will be useful to preparation of bio-based materials thought the liquefaction processes. In our study, two model woody components have been used under the different liquefaction conditions with phenol. In our experiments, the model cellulose component is specially used in the experiment to test the characteristics of the products under different ratios. As the results, we found that the final liquefied products from model component substance of lignin only 17.2% (wt) and the growth rate is very low with the molecular weight (Mw) up to 2119 under the reaction temperature of 150°C and 3 hours in the liquefaction experiments. However, the model cellulose component was confirmed to contribute more. On the contrary, the Mw of raw woody powder material can be reach to 1851. In a series of the mixing experiments, we found that the variation of Mw in the different experimental conditions determined by a gel permeation chromatography. From the results of liquefaction residue, we calculated the activation energy, and compared the value of those in different conditions. The solubility of the phenolated woody powder had been evaluated in eight organic solvents to evaluate the hydrogen bonding strengths of these solvents. It is very helpful for sustainable chemistry if polymeric materials can be effectively produced from the biomass liquefaction processes.

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Liquefaction Mechanism of β-O-4 Lignin Model Compound in the Presence of Phenol under Acid Catalysis. Part 1. Identification of the Reaction Products

Cited by 72 publications

References 21 publications

Optimization for microwave-assisted direct liquefaction of bamboo residue in glycerol/methanol mixtures

Optimization for microwave-assisted direct liquefaction of bamboo residue in glycerol/methanol mixtures

Polycondensation reaction and its mechanism during lignocellulosic liquefaction by an acid catalyst: a review

Characterization of liquefied products from model woody components in the presence of mineral acid catalysts

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