FUEL
·
2018
·
IF 4.908
Cheng Chen,Dongxue Jin,Xinping Ouyang,Lisha Zhao,Xueqing Qiu,Furong Wang
The structure of lignin is one of the key factors affecting its depolymerization into phenolic monomers . Four lignin fractions with different molecular weight were obtained by using ultrafiltration membrane technology , and the characteristics of lignin factions with different molecular weight were determined by gel permeation chromatography (GPC), potentiometric titration , FT-IR and NMR. It is found that wheat alkali lignin with low molecular weight contained more content of phenolic hydroxyl , methoxyl function groups, and β-O-4 linkages, which was relatively prone to depolymerize into phenolic monomers with a higher yield, although the more content of carbonyl was reported to facilitate the depolymerization of lignin. With the increase of molecular weight of lignin, the depolymerization was more difficult, and the YMC decreased. Lignin fraction with low molecular weight was favorable for depolymerization into syringyl and alkyl syringyl, while the high molecular weight lignin was prone to depolymerize into guaiacyl and alkyl guaiacyl products. Boric acid was proved effective to avoid repolymerization and improve the YMC, and the dosage of boric acid was determined by the content of hydroxyl groups in lignin.
研究领域:
生物化学
·
材料科学
✓ 已验证
DOI
高影响因子
Molecular Catalysis
·
2023
·
IF 4.6
Jian Xue,Da Wang,Xingjuan Li,Guangci Li,Zhong Wang,Yuanshuai Liu,Xuebing Li
A tandem strategy of “mild preoxidation-hydrogenolysis” was proposed for the efficient depolymerization of lignin. Firstly, a mild oxidation system was constructed with H 2 O 2 as the green oxidant and NaOH/Fe 2 (SO 4 ) 3 /CuO as the catalyst to pretreat lignin; then NiMoS catalyst was used for the further hydrogenolysis of the pretreated lignin. The reaction results showed that the strategy could achieve efficient lignin depolymerization. Under optimal conditions, the lignin liquefaction degree reached 91.1 wt.% and the monomer yield reached 20.6 wt.%. The structural analysis of the recovered lignin showed that the mild oxidation pretreatment could initially break the linkage bonds within the lignin molecule and get some large fragment molecules. Meanwhile, it also made the hydroxyl group in the C α position of the β-O-4 bond oxidized to carbonyl group, thus reducing the dissociation energy of the β-O-4 bond.
研究领域:
化学工程
·
生物质能
✓ 已验证
产品关联
DOI
高影响因子
ChemSusChem
·
2016
·Vol. 10
·期 3
·523-532
·
IF 7.116
Haiwei Guo,Bo Zhang,Zaojuan Qi,Changzhi Li,Jianwei Ji,Tao Dai,Aiqin Wang,Tao Zhang
Graphical W 2 C activity : Non-noble metal catalyst tungsten carbide shows high activity in the selective deconstruction of various lignin feedstocks to phenolic oils, and the impact of the structure differences on the activity of tungsten carbide is well studied. Softwood lignin shows lower hydrocracking efficiency than hardwood lignin, mainly owing to the higher molecular weights and the existence of more resistant linkages. Lignins isolated from representative hardwood, softwood, and grass materials were effectively hydrocracked to aromatics catalyzed by tungsten carbide over activated carbon (W 2 C/AC). The effects of botanical species and fractionation methods on lignin structure and the activity of W 2 C/AC were studied in detail. Gas permeation chromatography (GPC), FTIR, elemental analysis, and 2 D HSQC NMR showed that all the extracted samples shared the basic skeleton of lignin, whereas the fractionation method significantly affected the structure. The organosolv process provided lignin with a structure more similar to the native lignin, which was labile to be depolymerized by W 2 C/AC. Softwood lignins (i.e., spruce and pine) possessed higher molecular weights than hardwood lignins (i.e., poplar and basswood); whereas corn stalk lignin that has noncanonical subunits and exhibited the lowest molecular weight owing to its shorter growth period. β-O-4 bonds were the major linkages in all lignin samples, whereas softwood lignins contained more resistant linkages of β-5 and less β-β than corn stalk and hardwood lignins; as a result, lowest hydrocracking efficiency was obtained in softwood lignins, followed by corn stalk and hardwood lignins. 2 D HSQC NMR spectra of lignin and the liquid oil as well as the solid residue showed that W 2 C/AC exhibited high activity not only in β-O-4 cleavage, but also in deconstruction of other ether linkages between aromatic units, so that high yield of liquid oil was obtained from lignin.
研究领域:
化学工程
·
生物质能
✓ 已验证
产品关联
DOI
PubMed
高影响因子
BIORESOURCE TECHNOLOGY
·
2023
·
IF 11.4
Jiayi Zheng,Liheng Chen,Xueqing Qiu,Yingchun Liu,Yanlin Qin
Lignin is the most abundant natural phenolic polymer. However, the severe condensations of industrial lignin resulted in an undesirable apparent morphology and darker color, which hindered its application in the field of daily chemicals. Therefore, a ternary deep eutectic solvent is used to obtain lignin with light-color and low condensations from softwood. The results showed that the brightness value of lignin extracted from aluminum chloride-1,4-butanediol-choline chloride at 100 °C and 1.0 h was 77.9, and the lignin yield was 32.2 ± 0.6%. It is important that 95.8% of β-O-4 linkages (β-O-4 and β-O-4′) was retained. Lignin is used to prepare sunscreens and is added to physical sunscreens at 5%, with SPF up to 26.95 ± 4.20. Meanwhile, enzyme hydrolysis experiments and reaction liquid composition tests were also conducted. In conclusion, a systematic understanding of this efficient process could facilitate high-value utilization of lignocellulosic biomass in industrial processes.
研究领域:
生物化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
BIORESOURCE TECHNOLOGY
·
2016
·
IF 4.917
Guodian Zhu,Xueqing Qiu,Ying Zhao,Yong Qian,Yuxia Pang,Xinping Ouyang
A new two-step lignin depolymerization strategy was developed, in which the benzylic alcohols in lignin was methylated under microwave irradiation, followed by a hydrogenolysis for the cleavage of β O 4 bond with Pd/C as the catalyst. The results showed that an efficient and selective catalytic methylation of benzylic alcohols was achieved with various lignin model compounds, and the acidic environment promoted the methylation of benzylic alcohol. Methylation of benzylic alcohol increased the β O 4 bond cleavage rate by 55.9%, and improved products selectivity . Preliminary study of lignin depolymerization illustrated that methylation pretreatment of benzylic alcohols facilitated lignin depolymerization to produce aromatic monomers and reduced the oxygen content of aromatic monomers.
研究领域:
生物化学
·
可再生资源与环境科学
✓ 已验证
DOI
PubMed
高影响因子
PROCEEDINGS OF THE COMBUSTION INSTITUTE
·
2024
·
IF 5.3
Wen-luan Xie,Bin Hu,Xiao Yang,Ji Liu,Zhi-mo Fang,Kai Li,Yang-wen Wu,Bing Zhang,Qiang Lu
Phosphoric acid is an effective and widely used catalyst for biomass pyrolysis, with significant catalytic impact on the pyrolytic reactions and product distribution. However, its fundamental catalytic mechanism in lignin pyrolysis remains unclear. In this work, we proposed and investigated three possible H 3 PO 4 -assisted pyrolysis mechanisms, i.e., hydrogen-bond-induced decomposition, phosphoric-acid-assisted hydrogen transfer (H 3 PO 4 -AHT), and phosphorolysis, and carefully discussed them through theoretical calculations, electronic structure analyses, catalytic pyrolysis experiments using the β -O-4 linked lignin model. The results indicated that the H 3 PO 4 -AHT mechanism played a dominant role in lignin catalytic pyrolysis, superior to the other two mechanisms. The phosphoric acid molecule could take advantage of its unsaturated P = O and saturated P −OH groups for hydrogen donation and acceptance in concerted H 3 PO 4 -AHT reactions. Alternatively, it could also participate in concerted intermolecular hydrogen transfer with the active hydroxyl group as a mediator. The C β −O bond cleavage could be significantly enhanced by effectively reducing the tension of the transition state ring, leading to the generation of more phenol and styrene in pyrolysis experiments. Due to the inhibition of hydrogen abstraction, C α −C β breakage of β -O-4 linkage, side chain removal of primary products, etc., the formation of other products in phosphoric acid catalytic pyrolysis of β -O-4 linked lignin was restrained. This H 3 PO 4 -AHT catalytic mechanism was also confirmed to be conductive to tautomerism, elimination, dehydration, α -O-4 linkage fracture, β -1 linkage fracture, and other important decomposition reactions in lignin pyrolysis. The understanding of these mechanisms provides valuable insights into the role of phosphoric acid in lignin pyrolysis and may guide the development of effective biomass catalytic conversion methods.
研究领域:
化学工程
·
生物质能
·
催化科学
✓ 已验证
DOI
高影响因子
MOLECULES
·
2024
·Vol. 29
·期 23
·5683
·
IF 4.2
Zhuang Miao,Zhipeng Li,Xing Teng,Han Wang,Yingying Zhou,Yixin Qiu,Changming Li,Chunyu Liu,Yong Tan
Lignin is one of the building blocks of plant cell walls, and the study of the spectral characterization of its cleavage process can help to monitor the production and reuse of straw after decay. In this paper, four theoretical model structures of lignin formed by lignin G monomers and connected by β-O-4 bonding type were optimized and calculated based on the density functional theory using the B3LYP/3-21g and B3LYP/6-311g basis sets. The results showed that the theoretical infrared spectra of lignin increased sequentially in the absorption peaks of 1500 cm−1blue shift and 2932 cm−1and 1200 cm−1red shift, while the latter three theoretical models showed new infrared absorption peaks of 716 cm−1and 823 cm−1due to the presence of the β-O-4 structure, which is of great value for the theoretical spectral study of organic macromolecules and also provides data support for the spectral change in lignin in the degradation of graminaceous plants.
研究领域:
植物学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2020
·
IF 5.006
Feng Lin,Yulong Ma,Yonggang Sun,Xiuqin Men,Yingbo Zhu,Tingting Gao,Kanghe Zhao
Strategies for catalytic lignin depolymerization to yield ethylbenzene chemicals are green, sustainable and environmentally friendly methods. In this study, a series of Ni-CeO 2 /H-ZSM-5 catalysts were prepared via the precipitation method, which catalytically degraded the β-O-4 chemical bonding structure to yield ethylbenzene chemicals. The 2-(2-methoxy-phenoxy)-1-phenylethanol substance (β-O-4) was selected as a typical lignin model compound for the investigation of the intrinsic depolymerization mechanism and the catalytic performance. The results demonstrated that the introduced CeO 2 active phase can effectively promote the catalytic conversion of the β-O-4 chemical bonding structure to ethylbenzene chemicals. Physicochemical data demonstrate that the reaction pathways and hydrogenation selectivity were effectively regulated and controlled by the tuning of the dehydration and hydrogenolysis processes via the introduction of CeO 2 , which realized the selective adjustment of the redox properties and the surface valence states of active species in the catalytic process due to its excellent oxygen transfer performance.
研究领域:
催化化学
·
生物质转化
·
材料科学
✓ 已验证
DOI
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
·
2023
·
IF 5.9
Li-Li Sun,Yu Li,Xue-Fei Cao,Shuang-Quan Yao,Shao-Ni Sun
A deep eutectic solvent (DES, choline chloride/lactic acid)/2-methyltetrahydrofuran (2-MTHF) biphasic system was proposed to deconstruct the recalcitrance of Eucalyptus under different conditions for efficient extraction of lignin (DES-phase lignin (D-L) and organic-phase lignin (O-L)). The recovered lignin had relatively high total yield (61.65–83.69 %), low molecular weight (2400–1440 g/mol), and high purity. Results showed that the D-L had relatively higher aliphatic OH contents but lower phenolic OH contents than that of corresponding O-L, and the antioxidant activity of the O-L was higher than that of the corresponding D-L. Additionally, the total phenolic OH contents of the recovered lignin (1.92–2.96 mmol/g) were much higher than that of double enzymatic lignin (DEL, 1.29 mmol/g) because of the breakage of β - O -4′ linkages of the lignin in DES phase. Overall, the lignin fractions recovered from the DES and 2-MTHF phase has obvious difference, which is beneficial to the diversified utilization of lignin.
研究领域:
林业科学
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
GREEN CHEMISTRY
·
2024
·
IF 9.3
Jie Li,Pengpeng Shao,Weijie Geng,Peng Lei,Jing Dong,Yingnan Chi,Changwen Hu
The oxidative depolymerization of β-O-4 linkages into value-added aromatic chemicals is of great importance for lignin valorization. However, achieving highly selective and rapid cleavage of β-O-4 linkages under mild conditions remains a challenge. Herein, cobalt–cobalt oxides (Co-CoOx) supported on N-doped carbon (CoMA/C900) combined with a green and recyclable base K7HNb6O19 (KNb6) have shown remarkable activity for the one-step oxidative cleavage of lignin β-O-4 linkages. Under relatively mild conditions (100 °C, 0.2 MPa O2), a lignin β-O-4 alcohol model compound was almost completely converted within 3 h, affording a narrow product distribution of phenol (yield: 99%) and methyl benzoate (yield: 98%). Based on the control experiments, kinetic study, and spectroscopic analysis, a synergistic oxidative cleavage mechanism was proposed: CoMA/C900 activates molecular oxygen to form a superoxide radical, while basic KNb6 promotes deprotonation of secondary alcohol, and they synergistically catalyze the oxidation of β-O-4 alcohol and the rapid cleavage of Cβ–O and Cα–Cβ bonds. During the reaction, the oxidation of β-O-4 alcohol to β-O-4 ketone is the rate-determining step, while the cleavage of PP-one to phenol and methyl benzoate can be completed within 15 min. Moreover, the CoMA/C900–KNb6 catalyst is recyclable at least three times and highly active for the oxidative cleavages of other lignin models and organosolv birch lignin.
研究领域:
化学工程
·
材料科学
·
生物质转化
✓ 已验证
产品关联
DOI
高影响因子
ACS Omega
·
2021
·
IF 3.512
Xu Chen,Xingyu Ouyang,Jiayi Li,Yi-Lei Zhao
Laccase–mediator systems (LMSs) have been intensively investigated in lignin degradation. Although only natural metabolites are available for fungal lignin degradation, mediator molecules from metabolites have received substantially less attention than artificial organic–synthetic compounds. It remains unclear which metabolites can accelerate laccase-catalyzed reactions and how those natural mediators influence lignin degradation. In this work, we evaluated Trametes versicolor laccase-catalyzed reaction kinetics on a lignin guaiacyl subunit model (guaiacylglycerol-β-guaiacyl ether, G-β-GE) in the presence of a group of lignin syringyl subunit molecules: syringaldehyde, acetosyringone, and methyl syringate. We then compare their performance to a well-known synthetic mediator ABTS, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid). Time-resolved UPLC-TOF-MS revealed that the syringyl mediators were more effective in accelerating the β-O-4 cleavage and Cα-oxidation of G-β-GE than ABTS under laccase-catalysis, despite the syringyl compounds possessing slower individual oxidation rates. In addition, the product profile of polymerization was also promoted dramatically, compared to that of the ABTS/laccase system. The LMS kinetic modeling suggested that mediator–substrate aggregation played a critical role in the laccase–mediator system; in which, the lignin syringyl and guaiacyl subunits likely form a π–π stacking van der Waals complex that can be oxidized faster than the syringyl or guaiacyl monomers by themselves. This syringyl–guaiacyl aggregation hypothesis postulates that the weak interactions in lignin biopolymers are able to accelerate the laccase-catalyzed biodegradation.
研究领域:
生物化学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
GREEN CHEMISTRY
·
2024
·Vol. 26
·期 5
·2783-2792
·
IF 9.3
Jiayi Zheng,Liheng Chen,Zhichang Huang,Xueqing Qiu
Extraction of native-like lignin from lignocellulose is crucial for maximizing the value of all three major components of biomass. In this study, molecular dynamics was employed to reveal the essence of lignin condensation during the pretreatment of biomass with a promising acidic hydrotropic solution (AHS) at the molecular level. Diols were discovered to effectively suppress the excessive acidity of p-toluenesulfonic acid (pTsOH) in AHS while maintaining its solubilizing effect below a minimal hydrotropic concentration (MHC). The experimental results confirmed that the combined use of 1,4-butanediol and pTsOH can extract native-like lignin under mild conditions. The retention of lignin's β-O-4 linkages can exceed 90%, and the lignin extraction rate was over 80%. The obtained lignin can enhance the efficacy of chemical sunscreens, doubling the sun protection factor (SPF). Simultaneously, the residual cellulose was readily hydrolyzed into glucose by cellulase. This strategy demonstrates excellent adaptability to various biomass sources, including herbaceous species, hardwoods, and highly recalcitrant softwoods. The work lays the theoretical foundation for the precise control of biomass component separation using AHS, contributing to the development of mild and efficient component separation technologies in the future.
研究领域:
生物化学
·
可再生资源工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）