ChemSusChem
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2016
·Vol. 9
·期 22
·3220-3229
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IF 7.116
Haiwei Guo,Bo Zhang,Changzhi Li,Chang Peng,Tao Dai,Haibo Xie,Aiqin Wang,Tao Zhang
Graphical Breaking up : Tungsten carbide shows remarkable activity in selective C−O bond cleavage of typical β-O-4 model compounds and deconstruction of lignin feedstocks. High yields of C−O cleavage products from model compounds (up to 96.8 %) and from lignin feedstock (up to 70.7 %) are obtained without destroying the aromatic rings. A remarkably effective method for the chemoselective cleavage of the C−O bonds of typical β-O-4 model compounds and the deconstruction of lignin feedstock was developed by using tungsten carbide as the catalyst. High yields of C−O cleavage products (up to 96.8 %) from model compounds and liquid oils (up to 70.7 %) from lignin feedstock were obtained under low hydrogen pressure (0.69 MPa) in methanol. The conversion efficiency was determined to a large extent by solvent effects and was also affected by both the electronic and steric effects of the lignin model compounds. In situ W 2 C/activated carbon (AC)-catalyzed hydrogen transfer from methanol to the substrate was proposed to be responsible for the high performance in methanol solvent. The conversion of 2-(2-methoxyphenoxy)-1-phenylethanol showed that the catalyst could be reused five times without a significant loss in activity for C−O bond cleavage, whereas the selectivity to value-added styrene increased markedly owing to partial oxidation of the W 2 C phase according to X-ray diffraction, Raman spectroscopy, and transmission electron microscopy characterization. 2 D-HSQC-NMR spectroscopy analysis showed that W 2 C/AC exhibited high activity not only for β-O-4 cleavage but also for the deconstruction of more resistant α-O-4 and β-β linkages, so that a high yield of liquid oil was obtained from lignin. Corn stalk lignin was more liable to be depolymerized than birch lignin owing to its loosened structure (scanning electron microscopy results), larger surface area (BET results), and lower molecular weight (gel-permeation chromatography results), whereas its liquid oil composition was more complicated than that of birch wood lignin in that the former lignin contained more p -hydroxyphenyl units and the former contained noncanonical units.
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JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY
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2016
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IF 1.83
Zhijie Du,Wenzhi Li,Zhiping Xu,Hao Wu,Hasan Jameel,Hou-Min Chang,Long-Long Ma
Effects of a photocatalyst, C60-modified Bi2TiO4F2, on pine kraft lignin under visible light irradiation were investigated, along with those of Bi2TiO4F2 and C60/TiO2 as references. The influences of pH, C60 mass fraction, and the initial lignin concentration on lignin conversion and yields of mono-phenolic products were investigated. Seven products were determined by GC/MS, including phenol, 2-methoxyphenol, 4-ethyl-2-methoxyphenol, 2-methoxy-4-vinylphenol, vanillin, acetovanillone, and homovanillic acid. The yields of products and lignin conversion were higher by C60/Bi2TiO4F2 than Bi2TiO4F2 and C60/TiO2. C60/Bi2TiO4F2 and C60/TiO2 were more stable than Bi2TiO4F2 upon repetitive recycling of catalyst. The effectiveness of C60/Bi2TiO4F2 declines 25%, whereas that of Bi2TiO4F2 declines 56.4% after being recycled five times. FTIR and HRTEM indicated that the deactivation of photocatalysts might be caused by lignin adsorbed on the surface of photocatalysts and the change in the crystal structure.
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RSC Advances
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2016
·Vol. 6
·期 81
·77143-77150
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IF 3.289
Huajun Zhao,Qiujun Wang,Yonghong Deng,Qiao Shi,Yong Qian,Bingbing Wang,Lei Lü,Xueqing Qiu
For the common concern that general lignin-based colloidal spheres suffer the weakness of spherical structure destruction during the pyrolysis process, novel uniform lignin-derived nitrogen-doped carbon nanospheres were prepared by direct pyrolysis of lignin-based azo polymer (AL-azo-NO2) colloidal spheres at 750 °C. In addition, a kind of hard carbon with high graphitization degree was also prepared as a control by direct pyrolysis of alkali lignin (AL). The morphology and structure of the as-obtained carbon materials were investigated by field emission scanning electron microscopy, X-ray diffraction patterns, Raman spectra and elemental analysis. They served as anodes in lithium-ion batteries with the aim to investigate the electrochemical performance. These two kinds of lignin-derived carbon materials exhibited different electrochemical performances due to their various structures and functional groups. The nitrogen-doped carbon nanospheres (CSAN-750) exhibited a high cyclic stable capacity up to 225 mA h g−1 at a current density of 60 mA g−1 after 50 cycles (CAL-750, 120 mA h g−1) coupled with high first coulombic efficiency up to 66.4% for CSAN-3000 with a cyclic capacity of 200 mA h g−1, which is more comparable to that of the CAL-3000 (53.3%, 199 mA h g−1). This research indicates the great promise of lignin applied in producing hard carbon materials and further energy storage systems.
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APPLIED SURFACE SCIENCE
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2017
·
IF 3.387
Huan Wang,Xueqing Qiu,Weifeng Liu,Dongjie Yang
In this work, a novel lignin-based carbon/ZnO (LC/ZnO) hybrid composite with excellent photocatalytic performance was prepared through a convenient and environment friendly method using alkali lignin (AL) as carbon source. The morphological, microstructure and optical properties of the as-prepared LC/ZnO hybrid composite was characterized with scanning electron microscope (SEM), X-ray diffraction (XRD), Raman and UV–vis. The resulting LC/ZnO hybrid is composed of highly dispersed ZnO nanoparticles embedded on a lignin-based carbon nanosheet, showing excellent photogenerated electrons and holes separation and migration efficiency. The photocatalytic activity of LC/ZnO was much higher than the pure ZnO. The LC/ZnO hybrid composite showed different photocatalytic mechanism for degradation of negative methyl orange (MO) and positive Rhodamine B (RhB). It showed that h + was the main photocatalytic active group during the degradation of MO, ·O 2 − and ·OH were the photocatalytic active groups during degradation of RhB. This reported photocatalyst with selective degradation of positive and negative organic dyes may have a great application prospect for photoelectric conversion and catalytic materials. Results of this work were of practical importance for high-valued utilization of lignin for carbon materials.
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BIORESOURCE TECHNOLOGY
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2017
·
IF 5.651
Chenglun Tang,Junqiang Shan,Yanjun Chen,Lingxia Zhong,Tao Shen,Chenjie Zhu,Hanjie Ying
A novel and efficient organic amine and organosolv synergetic pretreatment method was developed to overcome the recalcitrance of lignocellulose to produce fermentable sugars and high-quality salt-free lignin. After optimization of the process parameters, a delignification of 81.7% and total sugar yield of 83.2% (87.1% glucose, 75.4% xylose) could be obtained using n -propylamine (10 mmol/g, biomass) as a catalyst and aqueous ethanol (60%, v/v) as a solvent. The susceptibility of the substrates to enzymatic digestibility was explained by their physical and chemical characteristics. The physical structure of extracted lignin showed higher β -aryl ether bonds content and functionalities, offering the potential for further downstream upgrading. The role of organic amine catalyst and a synergistic mechanism is proposed for the present system.
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BIORESOURCE TECHNOLOGY
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2014
·
IF 5.039
Riyang Shu,Jinxing Long,Zhengqiu Yuan,Qi Zhang,Tiejun Wang,Chenguang Wang,Longlong Ma
An efficient lignin depolymerization process with highly controllable product distribution was presented using metal chloride (MCl x ) cooperated with Pd/C. The catalytic performances of MCl x were investigated. The effect of reaction conditions on the lignin depolymerization and products distribution were also studied. Results showed that more than 35.4% yield of phenolic monomer including 7.8% phenols and 1.1% guaiacols could be obtained under optimized condition. And the product distribution can be efficiently controlled by the modification of the metal cation through different pathway of Lewis acid catalysis and coordination catalysis. Furthermore, the Pd/C catalyst showed an excellent recyclability, where no significant loss of the catalytic activity was exhibited after 3 runs. Moreover, the product control mechanism was proposed.
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APPLIED ENERGY
·
2014
·
IF 5.261
Jinxing Long,Ying Xu,Tiejun Wang,Zhengqiu Yuan,Riyang Shu,Qi Zhang,Longlong Ma
Serious char formation caused by the repolymerization of unsaturated decomposition products is a considerable challenge for current lignin utilization. Here, a novel and efficient base-catalyzed depolymerization and in situ hydrogenolysis process for lignin decomposition and char elimination was proposed using the synergic catalyst of NaOH coordinated with Ru/C. In which, lignin was first depolymerized to phenolic monomer and its oligomer, and then the oligomer was further converted to more stable aliphatic alcohols simultaneously. The results showed that more than 92.5% of lignin was converted, giving 12.69% phenolic monomer, 6.12% aliphatic alcohol and less than 14.03% residual solid. This residual solid selectivity was far lower than it from the single catalyst condition. Furthermore, the products were analyzed using GC–MS, GPC, HPLC–MS and 1 H NMR. The synergistic effect between depolymerization and hydrogenolysis was also investigated through comparative analysis of the feedstock, products, and the recovered lignin.
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MATERIALS LETTERS
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2014
·
IF 2.269
Zibin Guo,Zhe Liu,Li Ye,Kaikai Ge,Tong Zhao
Lignin-phenol-formaldehyde resin (LPF) derived submicron carbon fibers were successfully prepared by using LPF which was synthesized by using lignin as partial substitution of phenol in phenol-formaldehyde resin as precursor. The carbon fibers were obtained through electrospinning the LPF/polyvinylpyrrolidone (PVP)/dimethylformamide (DMF) solution followed by successive stabilization with BN preceramic polymer and carbonization processes. The chemical structure of LPF resin was studied by Fourier transform infrared spectroscopy (FTIR) and the morphology properties of carbon fibers were studied by scanning electron microscopy (SEM). The results showed that stabilized by immerging in BN precursor solution and then stabilized at 250 °C in the air, the morphology generated during the electrospinning processing was successfully retained throughout the stabilization and carbonization processes. LPF derived carbon fibers exhibited homogeneous diameter distribution and smooth surface.
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Polymers
·
2024
·Vol. 16
·期 10
·1403
·
IF 4.7
Shuyu Pang,Xin Wang,Jiali Pu,Chen Liang,Shuangquan Yao,Chengrong Qin
Hemicellulose extracted by alkali treatment is of interest because of the advantages of its intact sugar structure and high degree of polymerization. However, the hemicellulose extracted by alkali treatment contained more lignin fragments and the presence of a lignin–carbohydrate complex (LCC), which affected the isolation and purification of hemicellulose and its comprehensive utilization. Therefore, the evaluation of the LCC structure of different types of lignocellulosic resources is of great significance. In this study, the LCC structures of hardwoods and Gramineae were enriched in alkaline systems. Information on the composition, structural proportions, and connection patterns of LCC samples was discussed. The similarities and differences between the LCC structures of different units of raw materials were comparatively studied. The results indicated that the monosaccharide fractions were higher in the LCC of Gramineae compared to hardwoods. The composition of the lignin fraction was dominated by G and S units. The phenyl glycosidic (PhGlc) bond is the predominant LCC linkage under alkali-stabilized conditions. In addition, Gramineae PhGlc types are more numerous compared to hardwoods. The results of the study provide insights into the differences in the chemical composition and structural features of LCC in different plants and provide important guidance for the optimization of the process of purifying hemicellulose.
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FUEL
·
2024
·
IF 6.7
Yimin Xiong,Xuepeng Wang,Wei Deng,Peiyong Ma,Kai Xu,Jun Xu,Long Jiang,Yi Wang,Sheng Su,Jianlan Li,Song Hu,Jun Xiang
Biomass oxidative pyrolysis introduces restricted oxygen into the reaction zone, realizing autothermal pyrolysis to address the heat supply challenges inherent in large-scale applications. However, heavy components (＞200 Da) in bio-oil are critical precursors that lead to coke formation upon heating, which hinders the utilization of bio-oil. In this study, the conventional and oxidative pyrolysis experiments of cellulose, hemicellulose , and lignin in a fix-bed reactor were conducted at temperatures ranging from 300 °C to 800 °C, aiming to investigate the evolution of heavy components in bio-oil during biomass oxidative pyrolysis. The results showed that the addition of oxygen promoted the generation of bio-oil. Compared to conventional pyrolysis, the addition of oxygen mostly increased the yields of cellulose-oil, hemicellulose-oil, and lignin-oil by 28.21 %, 10.94 %, and 16.84 %, respectively. Further comprehensive analysis revealed that oxygen promoted the depolymerization of three components at a lower temperature range (＜ 500 °C). With increasing temperatures, oxygen enhanced the polymerization of volatiles from cellulose and lignin, where oxygen, acting as a binder, promoted the generation of phenolic compounds of heavy components in lignin-oil. Conversely, as the temperature increased, oxygen enhanced the oxidative decomposition of volatiles from hemicellulose, inhibiting the generation of heavy components in hemicellulose-oil. To sum up, this study presented a global evolution route of heavy components in bio-oil during oxidative pyrolysis of three components.
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CHEMICAL ENGINEERING JOURNAL
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2024
·
IF 13.3
Shicheng Wang,Xiaolei Guo,Xu Zhang,Haifeng Lu,Haifeng Liu
Reactive drying is a promising method for optimizing the drying and comminution of biomass. This paper investigated the reactive drying mechanism and the mechanical properties of three major components of biomass: cellulose (CL), hemicellulose (HL), and lignin (LN). The results indicated that HL was most significantly affected by temperature, with weight loss observed in the following descending order: HL > LN > CL. Based on FTIR and 13 C NMR analyses, the chemical structure changes of these three components differed and the reactive drying mechanism was revealed. Specifically, the temperature range of 105–150 °C was primarily associated with dehydration reactions, while processes such as depolymerization of CL and HL as well as decarboxylation of LN occurred within the temperature range of 150–200 °C. The Young’s modulus at different temperatures was measured using AFM, revealing that the Young’s modulus changes were ranked as HL > CL > LN. The impact of reactive drying on Young’s modulus could be attributed to the breakage of molecular chains due to the depolymerization of HL and CL, in addition to the thermal movement of the molecular chains.
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EUROPEAN POLYMER JOURNAL
·
2024
·
IF 5.8
Dou Li,Bailiang Xue,Qinyu Zhao,Wenliang Wang,Xinping Li,Jialong Wen,Zhiwen Wang,Wei Zhao
Lignin-based non-isocyanate polyurethanes (LNIPUs) represent a class of polymers synthesized from lignin—an abundant, renewable polymer found in the cell walls of plants—without the use of toxic isocyanates. This makes LNIPUs an eco-friendly alternative to traditional petroleum-based polyurethanes. Despite their advantages, the synthesis of LNIPUs often entails complex processes, the use of additional catalysts, and highly polar solvents, which largely restrict their accessibility and practical applications. In this study, we present an higly efficient, catalyst-free, and solvent-free methodology for synthesizing LNIPUs. A series of novel LNIPUs were successfully prepared through a one-pot, catalyst-free and solvent-free polymerization reaction involving aminated fractionated lignin (ALF E ) and bis(6-membered cyclic carbonate) (6CC). We systematically investigated the properties of the resulting LNIPUs, with a particular focus on the adhesion performance. The incorporation of ALF E significantly enhanced the adhesive properties of the resultant LNIPUs on aluminum, wood, and plastic substrates, achieving a maximum bonding strength of 3.09 MPa on aluminum. Furthermore, LNIPUs exhibit exceptional functionalities, including reusability, self-healing capabilities, and removability, along with improved thermal stability and photothermal properties.
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