Hydrolytic degradation of alkaline lignin in hot-compressed water and ethanol

Yuan, Zhongshun; Cheng, Shuna; Leitch, Mathew; Xu, Chunbao

doi:10.1016/j.biortech.2010.06.140

Cited by 240 publications

(144 citation statements)

References 29 publications

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“…5, Table 2). The dimers with a glycerol aliphatic chain might arise from cleavage from beta aryl ethers in hot alkaline conditions [29][30][31][32]. The occurrence of these dimers in 20°C samples hints that lignin degradation is occurring at these relatively low temperatures.…”

Section: Effects Of the Pretreatments On The Amount Of Lignin In The mentioning

confidence: 99%

Side by Side Comparison of Chemical Compounds Generated by Aqueous Pretreatments of Maize Stover, Miscanthus and Sugarcane Bagasse

et al. 2014

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In order to examine the potential for coproduct generation, we have characterised chemical compounds released by a range of alkaline and acidic aqueous pretreatments as well as the effect of these pretreatments on the saccharification ability of the lignocellulosic material. Comparative experiments were performed using three biomass types chosen for their potential as second-generation biofuel feedstocks: maize stover, miscanthus and sugarcane bagasse. The release of lignin from the feedstock correlated with the residual biomass saccharification potential, which was consistently higher after alkaline pretreament for all three feedstock types.Alkaline pretreatment released more complex mixtures of pentose and hexose sugars into the pretreatment liquor than did acid pretreatment. In addition, complex mixtures of aromatic and aliphatic compounds were released into pretreatment liquors under alkaline conditions, in a temperaturedependent manner, but far less so under acidic conditions. We show that the three feedstocks characterised interact with the pretreatment conditions in a specific manner to generate different ranges of products, highlighting the need to tailor pretreatments to both the starting feedstock and desired outcomes.

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Section: Effects Of the Pretreatments On The Amount Of Lignin In The mentioning

confidence: 99%

Side by Side Comparison of Chemical Compounds Generated by Aqueous Pretreatments of Maize Stover, Miscanthus and Sugarcane Bagasse

et al. 2014

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“…This indicated that a lengthy reaction time was not conducive to the depolymerization of alkali lignin in sub-and super-critical ethanol. A longer reaction time could lead to the mass of char was due to carbonization and recondensation between lignin-degraded products (Yuan et al 2010;Pińkowska et al 2012).…”

Section: Effect Of Reaction Conditions On the Yields Of Depolymerizatmentioning

confidence: 99%

Catalytic Depolymerization of Alkali Lignin in Sub- and Super-critical Ethanol

Guo¹,

Liu²,

Tang³

et al. 2017

BioResources

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The effects of reaction parameters on catalytic depolymerization of alkali lignin in sub-and super-critical ethanol were investigated using a high pressure autoclave, and the liquid oil and solid char products were characterized. The experimental data indicated that Rh catalysis, controlling reaction conditions at ethanol critical temperature (240 ºC) and pressure (7.0 MPa), high ethanol/water ratios (100/0), and the medium reaction time (4 h) enhanced the depolymerization of alkali lignin to liquid oil and decreased the char formation. A gas chromatography/mass spectroscopy (GC/MS) analysis showed that the main compositions of liquid oils were phenols, esters, ketones, and acid compounds, and the supercritical state favored the formation of bio-phenols, but the subcritical state improved the generation of bio-esters. Scanning electron microscopy (SEM) and Fourier transform infrared spectrometer (FTIR) spectra analysis showed that the addition of the Raney/Ni and Rh/C catalysis could inhibit the re-fusion of alkali lignin micron-sized spheres in the supercritical ethanol, which led to an increase in the occurrence of the depolymerization reactions.

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“…The yield rates of DEL increased with temperature until reaching a maximum at 250 °C. Various studies (Yuan et al 2010;Cheng et al 2012) of lignin have shown that the β-O-4 bond is readily ruptured at temperatures ranging from 200 to 300 °C (degradative reaction of lignin in various solvents). However, when the temperature was increased from 250 to 300 °C, the yield rate and reactivity toward formaldehyde of DEL considerably reduced, and residue rate largely increased.…”

Section: Effect Of Degradation Temperaturementioning

confidence: 99%

“…However, when the temperature was increased from 250 to 300 °C, the yield rate and reactivity toward formaldehyde of DEL considerably reduced, and residue rate largely increased. This indicated a possible repolymerization reaction between intermediates and oligomer products formed by C-C linkages or cross-linking with the side chains of the oligomer products (Yuan et al 2010). Therefore, the optimized temperature for lignin degradation was 250 °C.…”

Section: Effect Of Degradation Temperaturementioning

confidence: 99%

“…The alcohol-water co-solvent played an important role in the yield and composition of lignin. In fact, lignin and its derivative products (low molecular weight) showed good dissolution in the alcohol-water co-solvent, which can remarkably inhibit their repolymerization (Yuan et al 2010;Ye et al 2012). When the ratio of solid to liquid was 1:15, the yield rate and reactivity toward formaldehyde decreased.…”

Section: Effect Of Solid To Liquid Ratiomentioning

confidence: 99%

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Hydrothermal Degradation of Enzymatic Hydrolysis Lignin in Water-Isopropyl Alcohol Co-Solvent

Qiao

et al. 2016

BioResources

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The effect of hydrothermal conditions on enzymatic hydrolysis lignin (EHL) degradation in water-isopropyl alcohol co-solvent and optimal conditions were investigated. The yields and reactivity toward formaldehyde of degraded enzymatic hydrolysis lignin (DEL) were determined. The optimal conditions of temperature, time, and ratio of solids to liquids were 250 °C, 60 min, and 1:10 (w/v), respectively. The EHL and DEL were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), 1 H nuclear magnetic resonance ( 1 H NMR), thermal gravity (TG), and differential scanning calorimetry (DSC) analyses. The results revealed that the molecular weight and polydispersity of DEL were lower than that of EHL. Although the fundamental structure of lignin before and after hydrothermal degradation was retained, the ether (β-O-4, α-O-4, etc.) content decreased, while that of hydroxyl (phenolic and aliphatic) increased. The DTGmax and Tg values shifted from 334 and 117 °C to 304 and 105 °C, respectively.

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Hydrolytic degradation of alkaline lignin in hot-compressed water and ethanol

Cited by 240 publications

References 29 publications

Side by Side Comparison of Chemical Compounds Generated by Aqueous Pretreatments of Maize Stover, Miscanthus and Sugarcane Bagasse

Side by Side Comparison of Chemical Compounds Generated by Aqueous Pretreatments of Maize Stover, Miscanthus and Sugarcane Bagasse

Catalytic Depolymerization of Alkali Lignin in Sub- and Super-critical Ethanol

Hydrothermal Degradation of Enzymatic Hydrolysis Lignin in Water-Isopropyl Alcohol Co-Solvent

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