INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2022
·
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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产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2025
·
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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产品关联
DOI
PubMed
高影响因子
Reaction Chemistry & Engineering
·
2020
·Vol. 5
·期 5
·886-895
·
IF 3.441
Xing-Gang Si,Yun-Peng Zhao,Qing-Lu Song,Jing-Pei Cao,Rui-Yu Wang,Xian-Yong Wei
A highly efficient Ni/N–C catalyst was synthesized by facile pyrolysis of a Ni-containing metal–organic framework (Ni-MOF), and its catalytic hydrogenolysis performance towards C–O bonds in lignin was evaluated in detail using diphenyl ether (DPE) as a model compound. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses show that the flower-like nanosheets of the Ni-MOF shrink, forming a loose and ordered spherical structure during pyrolysis. Under the optimal conditions, DPE was completely converted and the selectivity to monomers (benzene, cyclohexanol and cyclohexane) reached 99.1%. During the catalytic hydrogenolysis conversion (CHC) of DPE, the direct cleavage of the Caromatic–O bond affording benzene and phenol is the major reaction pathway, and a low H2 pressure is crucial to increase the monomer selectivity. Furthermore, Ni/N–C-450 shows high hydrogenolysis activity for other lignin-derived aryl ethers, such as benzyl phenyl ether, dibenzyl ether, dinaphthalene ether, benzyl 2-naphthyl ether and 3-methoxyphenol.
研究领域:
化学工程
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催化材料科学
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DOI
高影响因子
POLYMER
·
2015
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IF 3.562
De-Ming Guo,Teng Fu,Chao Ruan,Xiu-Li Wang,Li Chen,Yu-Zhong Wang
In order to avoid the serious melt-dripping problems caused by conventional phosphorus flame retardants , a new arylene-ether containing monomer named 2,2′-(4,4′-(1,4-phenylenebis(oxy))bis(4,1-phenylene))bis(oxy) diethanol (PBPBD) was synthesized and introduced into the PET main-chain via condensation polymerization. With the incorporation of arylene-ether units, the thermal stability and the char residue from combustion of flame-retardant-element-free copolyesters containing PBPBD (BD x PETs) increased dramatically. However, the crystallinity and melting temperature of these copolymers were lower than the same quantities for PET. Thermal degradation kinetic was investigated using the Ozawa-Flynn-Wall method, which illustrated that the apparent activation energy for decomposition of the copolyesters was enhanced with increasing the conversion and the content of PBPBD. Py-GC/MS results showed that the PBBPD structural units undergo rearrangement reactions at high temperature, and ultimately form conjugated heteroaromatic structures, which lead to the formation of stable char residues with unique “stick-shaped” micro-morphology. Due to these rearrangement reactions, BD x PETs showed an expected flame retardant performance and a reduction in smoke generation during combustion. For example, the LOI value for BD 10 PET was 28.4, and the total smoke production (TSP) was 10.4 m 2 , much smaller than that for PET, 18.8 m 2 . Moreover, melt-dripping was restricted.
研究领域:
材料科学
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高分子化学
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产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2021
·
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
✓ 已验证
DOI
高影响因子
RSC Advances
·
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
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
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
·
可再生资源
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产品关联
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2013
·Vol. 20
·期 10
·1-9
·
IF 2.019
Liu Pengqing,Zeng Luxian,Ye Guangdou,Xu Jianjun
A series of co-polyarylates containing m -aryl ether units were synthesized from bisphenol A, 1,3-bis(4′-formylchloridephenoxy)benzene and terephthaloyl chloride via interfacial polycondensation in order to improve the processability of the bisphenol A-based polyarylate (U-polymer). The structure and properties of the co-polyarylates were characterized using infrared spectra, differential scanning calorimety, thermogravimetric analyses, wide angle x-ray diffraction and solubility testing, etc. The results show that the introduction of the asymmetry and flexible m -aryl ether units could improve the solubility obviously, but the solubility parameter of the co-polyarylate almost keeps a constant with changing the content of m -aryl ether units. As the content of m -aryl ether unit increases, the crystallization ability of the polyarylate weakens, meanwhile, the melting temperature shifts to low temperature as expected and the melting enthalpy reduces. When the content of the m -aryl ether units is higher than 60 %, the co-polyarylates become amorphous polymers. Moreover, there is almost no reduction of the thermal stability with increasing the content of the m -aryl ether units. In addition, the stability of each chemical bond of the co-polyarylate to thermal decomposition was systematically studied by means of pyrolysis-gas chromatography/mass spectrometry, and the thermal decomposition mechanism of the co-polyarylate was obtained.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
JOURNAL OF THE CHINESE CHEMICAL SOCIETY
·
2020
·Vol. 68
·期 4
·582-591
·
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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产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Guang-Hui Liu,Yong-Chao Qi,Han Wang,Ai-Min Wang,Yu-Hong Kang,Yong Gao,Ni Bai,Zhan-Ku Li,Xian-Yong Wei
This paper focused on the complementary advantages of density functional theory (DFT) calculation and catalytic reaction regulation. Based on the effective identification of intermediates, the possible catalytic hydroconversion (CHC) pathways of lignite-derived aryl ethers over Ni/mordenite were discussed. Bond dissociation energy (BDE) calculations of >C–O– bonds in different substrates and intermediates show that BDEs of >C ar –O– bonds are generally higher than those of >C al –O– bonds, and there is obvious electron aggregation near O atoms. Mulliken charge distribution analyses of different atomic sites further revealed the possible adsorption sites of active hydrogen, especially H · and H + . Possible cleavage pathways were further speculated by evaluating the stability of different leaving groups. In the early stage of CHC, aromatic ring hydrogenation and >C al –O– bond cleavage dominate, rather than >C ar –O– bond cleavage. Enthalpy change analyses combined with the CHC of real substrates further indicate that lowering temperature is beneficial to the cleavage of >C ar –O– bonds under the premise of inhibiting H ··· H transfer and obtaining H · effectively. Appropriately increasing the support acidity to ensure sufficient H + release is conducive to >C al –O– bond cleavage, especially direct dehydroxylation/dehydration. The analysis of synergetic transfer pathways of active hydrogen during the CHC provides theoretical guidance for the pathway optimization of converting lignite into high-quality clean liquid fuels.
研究领域:
化学工程
·
能源科学
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产品关联
DOI
高影响因子
ACS Catalysis
·
2019
·
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
·
环境科学
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2021
·Vol. 11
·期 9
·3241-3250
·
IF 6.119
Ming Jiang,Xiaopeng Chen,Linlin Wang,Jiezhen Liang,Xiaojie Wei
Selective hydrogenolysis of aryl ethers to produce aromatic compounds is a key strategy for lignin valorization. The use of non-noble-metal catalysts to realize the cleavage of C–O ether bonds under mild conditions has been of considerable research interest recently. We herein report the synthesis of a nitrogen-doped porous-carbon-skeleton-supported Ni–CeO2 catalyst (Ni–CeO2/CN). The synergistic effect between Ni and CeO2 species led to the Ni–CeO2/CN catalyst having a high activity and selectivity for the cleavage of C–O ether bonds at a low reaction temperature. In particular, the Ni–CeO2/CN catalyst showed excellent effectiveness in the hydrogenolysis of benzyl phenyl ether (α-O-4 bonds), and the full conversion was achieved after 2 h at a temperature of 60 °C, with phenol and toluene as the sole reaction products. In addition, the conversion of more robust β-O-4 ether bonds in 2-phenoxy-1-phenylethanol reached up to 100% with the yield of ethylbenzene and phenol at 150 °C for 2.5 h being 60.2% and 68.3%, respectively. The reusability-experiment results indicate that Ni–CeO2/CN maintained a high catalytic activity in five reaction runs, making this a promising route for C–O ether bond cleavage under mild conditions.
研究领域:
催化化学
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生物质转化
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材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）