INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2022
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IF 8.025
Lan Chen,Zhanming Liang,Xiaoxuan Zhang,Liming Zhang,Shuangfei Wang,Changzhou Chen,Ling Zeng,Douyong Min
Lignin is the most naturally abundant source of aromatics for phenolic chemicals, bioenergy sources, and functional materials. Recent works are devoted to the acid-catalyzed organosolv extraction for improving the lignin valorization. However, β –aryl ethers are mostly cleaved to form carbon–carbon bonds under the acidic condition. In this work, lignin isolated with methanolic hydrochloric acid (MHL) was compared with conventional milled wood lignin (MWL). The methanol incorporated into lignin as α –OCH 3 to prevent the cleavage of β –aryl ethers. As a result, the yield of MHL was over 12 times that of MWL. The MHL appeared a regular granular structure with an average diameter of 100 nm. Analysis of 13 C– 1 H HSQC NMR spectra showed that MHL contained 42.6 % β –O–4 linkages whereas 35.9 % for the MWL, as well as 6.5 % β –5 and 3.2 % β – β , which was less than MWL. Moreover, 13 C NMR spectroscopy confirmed that MHL was mainly isolated by the cleavage of the associated carbohydrates rather than the degradation of β –aryl ether bonds. Therefore, MHL can be utilized more as a native lignin representative than MWL for studying the physicochemical properties and the interior structures of the protolignin.
研究领域:
生物化学
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材料科学
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DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2025
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IF 8.5
Tianyuan Xiao,Jiahui Song,Wenchao Jia,Yanning Sun,Yanzhu Guo,Pedram Fatehi,Haiqiang Shi
The chemical bond cleavage of lignin is a research focus for achieving depolymerized lignin for such applications as adhesives, fuels, fertilizers, etc. The depolymerization of an industrially available sustainable material, i.e., industrial alkali lignin, in LiBr·3H 2 O/HBr-γ-valerolactone (GVL) was systematically investigated in this study. It was observed that using 3/1 mL/g of HBr/lignin and 8/1 mL/g of GVL/lignin at 110 °C for 90 min, i.e., optimized conditions, resulted in lignin derivatives with an M w of 1889 g/mol and M n of 895 g/mol. The characteristics of the products were studied using FTIR, NMR, SEM, and DLS techniques. The results confirmed that the Hibbert-ketone end group was formed, while the structure of the aromatic ring was not changed on the depolymerized lignin. After the depolymerization process, the hydroxyl content in lignin increased from 1.91 mmol/g to 2.96 mmol/g. The product derived from the LiBr·3H 2 O/HBr-GVL depolymerization system displayed a spherical particle morphology. The addition of GVL to lignin depolymerization processes improved the bonding between lignin and inorganic molten salts, thereby promoting the acid-catalyzed cleavage of aryl ether bonds in lignin. Current research supports the conclusion that LiBr·3H 2 O/HBr-GVL lignin depolymerization is a sustainable and effective chemical pathway for generating depolymerized lignin.
研究领域:
化学工程
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材料科学
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DOI
PubMed
高影响因子
APPLIED CATALYSIS A-GENERAL
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2021
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IF 5.706
Huihuang Fang,Lijie Wu,Weikun Chen,Youzhu Yuan
Transition-metal carbides are attractive heterogeneous catalysts for the transformation of lignin-derived compounds. However, the effects of the surface carbon defect (C-defect) remain unclear due to coke deposition and exposed C terminations. Herein, we transform inert tungsten carbides (WC) into active catalysts via surficial C-etching using transition metals in the presence of H 2 . An optimized 1% Pt–WC catalyst with synergy of Pt and C-defects can perform a 78.6% conversion in the selective hydrogenolysis of guaiacol to phenol with 89.0% selectivity at 300 °C, while the intact WC only gives a 7.1% guaiacol conversion with 51.0% phenol selectivity under the same conditions. As a result, the 1% Pt–WC catalyst exhibits 19-fold higher reaction rate and 12.6-fold higher turnover frequency than those of WC. Moreover, no substantial loss of catalytic performance has been observed with 1% Pt–WC for 50 h on stream. A rational reaction pathway is accordingly proposed through in-depth characterizations.
研究领域:
化学工程
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催化材料
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DOI
高影响因子
RSC Advances
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2016
·Vol. 6
·期 87
·84284-84293
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IF 3.289
Wen-Qiang Zhang,Xiu-Li Wang,Gui-Cheng Liu,Li Chen,Yu-Zhong Wang
In order to make clear how the numbers of para-aryl ether linkages affect the solubility, thermal transition behavior and mechanical properties of para-(p-PEAs), meta-poly(ether-amide)s (m-PEAs), a series of para-substituted aryl ether diamine monomers with 2, 3, 4 or 5 ether linkages were synthesized, and then reacted with terephthalic acid and isophthalic acid via the Yamazaki–Higashi phosphorylation method to prepare wholly aromatic PEAs. The PEAs with intrinsic viscosity values in the range of 0.81–1.16 dL g−1 were obtained and characterized by FT-IR, NMR, and elemental analysis. Although the Tgs and Tms of PEAs decrease with the increasing numbers of aryl ether linkages, their Tgs and Tms still are above 180 °C and 320 °C, respectively. p-PEAs have a high crystallinity making it difficult to dissolve them in common organic solvents even when 5 aryl ether linkages are introduced. Conversely, except for m-PEA5 with a lower polarity, the other m-PEAs show good solubility due to their low crystallinity. Besides, the decomposition temperatures at 5% weight loss of all PEAs exceed 430 °C and their residual yields at 700 °C are above 50% in N2, illustrating that they have excellent thermal stability. It is found that by casting m-PEAs DMAc solution in a dish, the transparent films with high Young's modulus (2.6–3.5 GPa) can be successfully obtained.
研究领域:
材料科学
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高分子化学
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DOI
高影响因子
FUEL
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2022
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IF 8.035
Guodian Zhu,Yuehua Wu,Yuebin Xi,Shaoqu Xie,Guoqiang Yin,Xiaojing Lv,Xuliang Lin
Lignin has immense potential for the production of monoaromatics that can be further prepared as target chemicals or alkyl biofuels. In this work, experiments and density functional theory (DFT) calculations were employed to investigate the effect of benzylic alcohol ( α -hydroxyl group, C α H─OH) dehydration to α , β -alkenyl group (C α = C β ) on the enhancement of the β -aryl ether ( β -O-4) bond cleavage reactivity of lignin model dimer over Pd/C by formic acid. This study demonstrated that the β -O-4 bond cleavage reactivity was significantly enhanced via the benzylic alcohol dehydration to C α = C β . The cleavage reactivity of the β -O-4 bond attached to C α functional groups was in the order of α -hydrogen atom (C α H─H) > C α H─OH > α -carbonyl group (C α = O). An easy formation of the C α H─H from the C α = C β hydrogenation led to the enhancement of the β -O-4 bond cleavage reactivity being achieved. The β -O-4 bond cleavage rate was increased by 6.2 times in the presence of the C α H─H compared to the C α = O. Due to few and lower required energy barriers after C α H─OH dehydration, the β -O-4 bond attached to the C α = C β was more thermodynamically favorable to be cleaved. The work highlights the prospect of efficient depolymerization of lignin into monoaromatics.
研究领域:
化学工程
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可再生资源
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DOI
高影响因子
JOURNAL OF THE CHINESE CHEMICAL SOCIETY
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2020
·Vol. 68
·期 4
·582-591
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IF 1.554
Changzhou Chen,Peng Liu,Haihong Xia,Minghao Zhou,Jianchun Jiang
There is an urgent need to develop a selective hydrogenolysis of C aryl -O bonds in lignin to produce valued-added chemicals and fuels. Recently, hydrogen has been used in the hydrogenation reaction, which hides inevitable danger and is not economical. Therefore, isopropanol, as a hydrogen-donor solvent, is employed for aryl ether hydrogenolysis in lignin models over nickel supported on a carbon nanotube (CNT). Except for aromatic ether (4-O-5), the Ni/CNT catalyst is also found to be suitable for alkyl-aryl ether (α-O-4 and β-O-4) cleavage in control experiments. The physicochemical characterizations were carried out by means of H 2 -temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. The catalyst can be magnetically recovered and efficiently reused for five consecutive recycling tests in the transfer hydrogenation of aromatic ethers. A mechanism study indicated that the hydrogenolysis cleavage of the ether bond is the first step in the reaction process, and hydrogenation of aromatic rings is only a successive step in which phenol and benzene are intermediate states and are then further hydrogenated. Furthermore, it has been demonstrated that aryl groups play an important role in the hydrogenation of phenol in the competitive catalytic hydrogenation reaction of phenol.
研究领域:
化学工程
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催化科学
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DOI
高影响因子
ACS Catalysis
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2019
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IF 12.221
Hongji Li,Anon Bunrit,Jianmin Lu,Zhuyan Gao,Nengchao Luo,Huifang Liu,Feng Wang
Depolymerization of lignin meets the difficulty in cleaving the robust aryl ether bond. Herein, through installing an internal nucleophile in the β-O-4′ linkage, the selective cleavage of aryl ether was realized by the intramolecular substitution on aryl rings affording non-phenolic arylamine products. In particular, nitrogen-modified lignin models and lignin samples were employed to generate the iminyl radical under photocatalytic reduction, which acted as the internal nucleophile inducing aryl migration from O to the N atom. The following hydrolysis released primary arylamines and α-hydroxy ketones. Mechanism studies including electron spin resonance (ESR), fluorescence quenching experiments, and density functional theory (DFT) calculations proved the aryl migration pathway. This method enables access to non-phenolic arylamine products from lignin conversion.
研究领域:
化学
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能源
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环境科学
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DOI
高影响因子
ACS Sustainable Chemistry & Engineering
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2024
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IF 7.1
Xiaomeng Yang,Fei Geng,Zhengzeng Yang,Armin Rezayan,Chunbao Charles Xu,Dan Wu,Yongsheng Zhang
Reductive catalytic fractionation (RCF) is a promising lignin-first strategy to produce valuable phenolics from lignocellulosic biomass. However, this method encounters the challenges of a low yield of phenolic monomers and the use of expensive noble metal catalysts. In this study, a reduced NiAl layered double oxide (NiAl-LDO) catalyst is reported for the RCF of lignocellulosic biomass with high depolymerization efficiency and phenolic monomer yields. The RCF reaction of pine at 260 °C yielded 27.49 wt % of lignin oil and 21.62 wt % of phenolic monomers, with a delignification degree of 92.62%. In addition, high-performance liquid chromatography analysis showed that the solid carbohydrate pulp fraction retained up to 80.63% cellulose, which can be used as an economical feedstock for the production of other platform chemicals. Further characterization and mechanistic studies including NH3-TPD, Py-FTIR, and 2D HSQC NMR revealed that the strong acidic sites derived from Ni2+ at the metal–support interface play a crucial role in promoting the hydrogenolysis of aryl ether bonds within lignin, thereby significantly improving the yield of phenolic compounds. Understanding the role of the NiAl-LDO catalyst acidity in the RCF reaction is beneficial for the production of phenolic products from biomass based on a lignin-first strategy.
研究领域:
化学工程
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催化
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可再生能源
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生物炼制
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DOI
高影响因子
RSC Advances
·
2020
·Vol. 10
·期 71
·43599-43606
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IF 3.119
Xiaomeng Dou,Wenzhi Li,Chaofeng Zhu,Xiao Jiang,Hou-min Chang,Hasan Jameel
Efficient cleavage of aryl–ether linkages is a key strategy for generating aromatic chemicals and fuels from lignin. Currently, a popular method to depolymerize native/technical lignin employs a combination of Lewis acid and hydrogenation metal. However, a clear mechanistic understanding of the process is lacking. Thus, a more thorough understanding of the mechanism of lignin depolymerization in this system is essential. Herein, we propose a detailed mechanistic study conducted with lignin model compounds (LMC) via a synergistic Co–Zn/Off-Al H-beta catalyst that mirrors the hydrogenolysis process of lignin. The results suggest that the main reaction paths for the phenolic dimers exhibiting α-O-4 and β-O-4 ether linkages are the cleavage of aryl–ether linkages. Particularly, the conversion was readily completed using a Co–Zn/Off-Al H-beta catalyst, but 40% of α-O-4 was converted and β-O-4 did not react in the absence of a catalyst under the same conditions. In addition, it was found that the presence of hydroxyl groups on the side chain, commonly found in native lignin, greatly promotes the cleavage of aryl–ether linkages activated by Zn Lewis acid, which was attributed to the adsorption between Zn and the hydroxyl group. Followed by the cobalt catalyzed hydrogenation reaction, the phenolic dimers are degraded into monomers that maintain aromaticity.
研究领域:
化学工程
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催化
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有机化学
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木质素解聚
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DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）