APPLIED ENERGY
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2022
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IF 11.446
Tan Li,Jing Su,Huiyuan Wang,Cong Wang,Wen Xie,Kaige Wang
NiMo-doped catalysts were investigated for the conversion of lignin to drop-in fuel through catalytic hydropyrolysis. The influence of NiMo-doped catalysts with different carriers and Ni/Mo molar ratios on the hydropyrolysis product distribution were studied using both lignin and lignin model compounds. Two coefficients were proposed to qualitatively evaluate the catalytic performance of NiMo-doped catalysts. Low yield of methane (13.04c%) and high yield of condensable hydrocarbons products (25.82c%) with low selectivity of polyaromatics (4.37%) were obtained at 1.0 MPa H 2 and 400 °C catalytic temperature during lignin catalytic hydropyrolysis over Ni 1 Mo/ZrO 2 . The hydrodeoxygenation activity of Ni x Mo/ZrO 2 depends on Ni 0 , Mo 4+ , and Mo 3+ . The synergistic effect of Ni and Mo promotes the removal of the phenolic methoxy group. The increase in hydrogen pressure tends to make hydrogen to be consumed through hydrocracking and hydrogenation reactions. The influence of Ni 1 Mo/ZrO 2 on evolution of lignin hydropyrolysis volatiles was revealed. Ni shows strong activity in the removal of phenolic hydroxyl groups and benzene ring hydrogenation, while Mo tends to remove phenolic methoxy groups.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2022
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IF 8.025
Tian He,Fangeng Chen,Wenxiang Zhu,Ning Yan
There is a strong interest in developing environmentally friendly synthesis approaches for making polyurethane elastomers (PUE) with desirable mechanical performance and flame retardancy suitable for a variety of applications. Hence, in this study, a novel nano functionalized lignin nanoparticle (Nano-FL) containing nitrogen (N) and phosphorus (P) moieties was developed via mild grafting reactions combined with the ultrasound method. The Nano-FL incorporated in the PUE acted as both crosslinking agents and flame retardants. The novel Nano-FL showed good compatibility and dispersibility in the PUE matrix, thereby overcoming the weakening effect of adding traditional lignin flame retardants on the mechanical properties of the PUE materials. PUE/Nano-FL exhibited strong tensile properties. Compared with control neat PUE, with 10 wt% of Nano-FL addition, the PUE attained a limiting oxygen index as high as 29.8% and it also passed the UL-94 V-0 rating. Furthermore, Cone Calorimetry Test (CCT) showed that the addition of Nano-FL not only reduced the heat release rate and the total heat release but also decreased the total smoke production rate during combustion. The char residues of PUEs with Nano-FL showed a high oxidation resistance with dense and continuous structural morphologies. The combined barrier and quenching effects of the char layer provided excellent flame retardancy performance. The novel Nano-FL developed in this study showed excellent promises as green functional additives for enhancing mechanical, thermal and flame retardancy performance of a wide range of polymers.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2022
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IF 7.139
Riyang Shu,Linxuan Zhou,Zhengchen Zhu,Bowen Luo,Hongyun You,Zhuojie Zhong,Yao He
Enzymatic hydrolysis lignin is a kind of byproduct from the biorefinery process, and hydrogenolysis is a promising approach to valorize the lignin waste. This work proposed an efficient hydrogenolysis of enzymatic hydrolysis lignin over in situ prepared RuNi/C bimetallic catalyst . RuNi/C catalyst exhibited a much higher catalytic activity than Ru/C catalyst with the addition of Ni species. A series of characterizations were carried out to reveal the synergistic effect of the bimetallic catalyst . The results indicated that the interaction between Ru and Ni formed an electron transfer from Ru to Ni and resulted in intensified hydrogen adsorption, which was the crucial factor for the enhanced hydrogenolysis performance. The reaction condition of lignin hydrogenolysis was optimized, and 20.4 wt% monomer product yield was achieved at the temperature of 280 °C. This catalytic system is easy to realize and promising to be employed in the field of lignin utilization.
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JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2022
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IF 6.437
Zijun Yi,Chao Li,Lijun Zhang,Shu Zhang,Wenran Gao,Shuang Wang,Bin Li,Xun Hu
CO 2 can be used to activate biomass for production of activated carbon at high temperatures (usually above 700 °C). At typical pyrolysis temperatures, CO 2 might also involve in biomass pyrolysis , which was investigated via pyrolysis of lignin at temperatures from 400 to 700 °C in N 2 and CO 2 atomsphere, respectively. The results suggested that CO 2 interfered with the pyrolysis process, facilitating formation of bio-oil and biochar but not gases via suppressing further gasification of volatiles. This reserved more mono-ring phenolics in bio-oil and also formed more heavier phenolics through secondary condensation routes. As for biochar, CO 2 enhanced the aromatization process, generating the carbon-rich biochar of higher heating value . The in-situ characterization of the functionalities of biochar during pyrolysis suggested that CO 2 accelerated removal of the aliphatics like -OH, -C-H, C O, and C-O-C. This rendered the biochar of hydrophobic surface but less fragmentized structures than that obtained in N 2 .
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BIORESOURCE TECHNOLOGY
·
2022
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IF 11.889
Hailian Gao,Jiebin Wang,Meixuan Liu,Shunxin Wang,Wenbo Li,Qingda An,Kunlan Li,Ligang Wei,Chi Han,Shangru Zhai
The aerobic oxidation of lignin model 2-phenoxyacetophenone (2-PAP) in cooperative ionic liquid mixtures (CoILs) with 1-ethyl-3-methylimidazolium acetate ([C 2 C 1 im]OAc) and 1-benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([B Z C 1 im]NTf 2 ) was investigated. Complete degradation of 2-PAP was achieved with [C 2 C 1 im]OAc/[B Z C 1 im]NTf 2 molar ratio ( R IL ) of 1/1 and 1/2 at 100 °C for 2 h. The conversion and product yields from CoILs were higher than those in pure ILs, indicating the cooperative effects of [C 2 C 1 im]OAc/[B Z C 1 im]NTf 2 on cleaving aryl–ether bonds. [C 2 C 1 im]OAc promoted the catalytic cleavage of aryl–ether bonds and solvation, and [B Z C 1 im]NTf 2 induced the formation of alkyl radicals and enhanced the product selectivity. Accordingly, the highest conversion of alkali lignin (79.8%) was obtained with R IL of 5/1 at 100 °C for 2 h, and phenol monomers (306 mg/g) were selectively produced. The CoILs exhibited good catalytic capacities for oxidative depolymerization of lignin, which strongly depends on the changes in intermolecular interactions and structural organization with varying R IL .
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CHEMICAL PHYSICS LETTERS
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2022
·
IF 2.719
Jie Xu,Feng Lin,Jingyu Wang,Yujie Wang
Photocatalytic cleavage of lignin C O bonds is a promising way to depolymerize lignin into aromatic value-added chemicals. However, the dispersibility of lignin in solvents and photocatalytic efficiency still face great challenges. Here, a micelle aqueous medium (CTAB-15) composed of hexadecyl trimethyl ammonium bromide and water was successfully prepared. 2-phenoxy-1-phenylethanol (lignin model compounds, PPol) and dioxanesolv poplar lignin have a good dispersion in CTAB-15. Compared to the previous reports, the highest photocatalytic efficiency can be obtained under optimal conditions by using the photocatalyst CdS. The main products formed by photocatalytic cleavage of lignin C O bonds are phenols and ketones. Mechanism studies show that CTAB-15 can provide sufficient hydrogen by photo-driven dissociation of water for photocatalytic cleavage of lignin C O bonds, which is critical to rapidly improving photocatalytic efficiency. The hydrogen, which is used to form acetophenone, comes from H 2 O and PPol. However, the hydrogen needed to form phenol comes only from PPol itself. In addition, the photocatalytic reaction follows a photogenerated electron-hole coupled redox process. This work develops a new direction for promoting the high-value utilization of lignin.
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INDUSTRIAL CROPS AND PRODUCTS
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2022
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IF 6.449
Yi Wei,Siyao Zhu,Qianwen Qian,Qiuran Jiang,Liying Zhang,Kejia Jin,Wanshuang Liu,Yiping Qiu
Lignin, a low-cost and abundant polyphenol biomass, has considerable potential to develop sustainable flame retardants for polymers due to its aromatic skeleton and high char-forming capability after combustion. In order to integrate phosphorous and nitrogen elements, herein lignin was facilely modified by hexachlorocyclotriphosphazene through a one-step nucleophilic substitution reaction. The functionalized lignin (Lig-HCCP) was used as an additive to improve the flame retardancy of epoxy resins. The effects of Lig-HCCP with different loading levels on the curing behaviors, rheological characteristics , as well as thermal, mechanical, and flame-retardant properties of the resulting epoxy composites were studied in detail. Notably, the epoxy composite containing 20 wt% Lig-HCCP showed the highest limited oxygen index (LOI) of 28.2% and achieved a UL-94 V-0 rating in the vertical burning test. Furthermore, the results of cone calorimeter tests indicated that the peak heat release rate, heat release rate, and total smoke production of the epoxy composite were decreased by 58.9%, 38.5%, and 63.1%, respectively, compared with the control resin. The flame retardant mechanisms could be ascribed to the P-N synergy and abundant aromatic structures in Lig-HCCP, which contributed to the formation of intumescent and compact char layers. This work demonstrates a simple and promising approach to utilize lignin feedstocks for value-added flame retardants.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2021
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IF 5.279
Di Fan,Xinyi Xie,Canxin Li,Xingwang Liu,Jian Zhong,Xinping Ouyang,Qiyu Liu,Xueqing Qiu
The traditional pretreatment leads to the recalcitration of C–C bonds during lignin fractionation, thus hindering their depolymerization into aromatic monomers. It is essential to develop an applicable approach to extract noncondensed lignin for its high-value applications. In this work, noncondensed lignins were extracted from poplar sawdust using recyclable p-toluenesulfonic acid for cleaving lignin–carbohydrate complex bonds effectively and ethanol as a stabilization reagent to inhibit lignin condensation. Lignin yield of 83.74% was recovered by 3 mol/L acid in ethanol at 85 °C for 5 h, and carbohydrates were well preserved (retaining 98.97% cellulose and 50.01% hemicelluloses). During lignin fractionation, the acid concentration and extraction time were the major drivers of condensation. Ethanol reacted with lignin at the α-position to prevent the formation of the condensed structure. The extracted lignin depolymerized over the Pd/C catalysts gave a yield of 50.35% of aromatic monomers, suggesting that the novel extraction process provided a promising way for noncondensed lignin production.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2021
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IF 6.953
Lingyan Zhu,Dongbing Li,Heng Lu,Shangkun Zhang,Hao Gao
The synthesis of lignin-based graphene quantum dots (GQDs) with excellent fluorescence stability, quantum yield , and biocompatibility for sensitive and selective detection of Fe 3+ and ascorbic acid (AA) has remained a challenging endeavor. Using an acidolysis process with 17.5% nitric acid followed by hydrothermal treatment at 200 °C, this study provided an improved synthesis route for the production of high-quality GQDs from alkali lignin. The nitrogen-doped GQDs exhibit remarkable fluorescence stability under a wide range of pH (3–10), duration (1–12 h), and [NaCl] (0–1000 mM) conditions, and have a high quantum yield of 28%. The GQDs or GQDs/Fe 3+ sensing systems ([GQDs] at 50 mg L −1 , [Fe 3+ ] at 500 μmol L −1 , and UV excitation at 370 nm) for fluorescence sensing of Fe 3+ or AA have excellent sensitivity, selectivity, and reproducibility. For Fe 3+ and AA, the limit of detection is 1.49 and 1.62 μmol L −1 , respectively. Mechanism investigation shows that photoluminescence quenching is caused by the formation of GQDs-Fe 3+ complexes, whereas fluorescence recovery is due to Fe 3+ reduction by AA.
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CHEMICAL ENGINEERING JOURNAL
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2021
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IF 13.273
Jie Wang,Yaxun Fan,Hongliang Wang,Jiaming Yin,Weiming Tan,Xue Li,Yutan Shen,Yilin Wang
Photolysis and migration seriously reduce utilization efficiency of photosensitive agrochemicals, which leads to vast losses of ecological and economic benefits. Here we develop a novel method for preparing water-based coacervate as a stabilizer for photosensitive agrochemicals by utilizing single-chain/gemini surfactants and sodium lignosulfonate (SL), a renewable and ubiquitous biopolymer abandoned by pulping industry that presents excellent intrinsic ultraviolet (UV) resistance. Coacervates contain intricate nanoscale networks and abundant bound water, resulting in highly effective encapsulation of hydrophilic and hydrophobic solutes, and entanglement with the micro- and nanostructures of a superhydrophobic surface without sacrificing its ability to resist UV degradation. These coacervates display a high encapsulation efficiency for photosensitive abscisic acid (ABA) up to 90%, and resist UV degradation for 70 times longer than that in pure water, and act as an optimal substrate for the deposition of encapsulated agrochemicals on superhydrophobic leaves after high-speed impact. As a result, the drought resistance of wheat seedlings is significantly improved after spraying ABA protected by SL-coacervates, compared with free ABA, demonstrating that agrochemicals sequestered in coacervates effectively alleviate photolysis and migration loss. Thus, using a lignin-based coacervate can be used to potentially promote productive and sustainable agriculture, by serving as a highly efficient and environmental-friendly stabilizer for photosensitive agrochemicals used in pesticide applications.
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RSC Advances
·
2021
·Vol. 11
·期 47
·29178-29185
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IF 3.361
Ying Wang,Yushan Liu,Jin Zhou,Jinquan Yue,Mingcong Xu,Bang An,Chunhui Ma,Wei Li,Shouxin Liu
This work assessed the fabrication of nitrogen-doped CQDs (NCQDs) from alkali lignin (AL) obtained from spruce, representing a green, low-cost biomass generated by the pulp and biorefinery industries. The AL was found to retain its original lignin skeleton and could be used to produce NCQDs with excellent photoluminescence properties by one-pot hydrothermal treatment of AL and m-phenylenediamine. These NCQDs exhibited blue-green fluorescence (FL) with excitation/emission of 390/490 nm under optimal conditions. The NCQDs showed pH and excitation wavelength-dependent FL emission behaviors. On the basis of the exceptional selective response of these NCQDs to specific solvents, we developed a FL probe for the detection of formaldehyde (FA). The FL intensity of NCQDs was found to be directly proportional to the concentration of FA in the range of 0.05 to 2 mM (R2 = 0.993), with a detection limit of 4.64 µM (based on 3σ/K). A composite film comprising NCQDs with poly(vinyl alcohol) was found to act as a sensor with a good FL response to FA gas. When exposed to gaseous FA, this film exhibited increased FL intensity and transitioned from blue-green to blue. A mechanism is proposed in which the NCQDs react rapidly with FA to generate Schiff bases that result in enhanced FL emission and the observed blue shift in color.
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Materials Today Chemistry
·
2021
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IF 8.301
G. Yan,S. He,N. Ding,Y. Lee,Y. Sun,X. Tang,X. Zeng,L. Lin
Recently, conductive hydrogels with multifunctionality have attracted much attention for various applications such as soft robotics and stretchable bioelectronics. Nonetheless, it remains a grand challenge to prepare conductive hydrogels with high strength and toughness at room temperatures without any external energy input. Here, the free radical polymerization of a lignin-based conductive hydrogel simultaneously featuring strong, tough, transparent, and self-healing properties is efficiently induced by a catalytic system comprised of tin metal ions and lignin molecules at room temperature without any external energy input. The tin ions and catechol groups contained in lignin can generate large amounts of hydroxyl radicals under the effect of ammonium peroxydisulfate. These free radicals can trigger the rapid self-gelation of the hydrogels at mild conditions within a few seconds (∼10 s). The dynamic cross-linking between the tin ions and catechol groups of lignin molecules in the hydrogel network endows the material with a tensile strain up to ∼1800%, which is far superior to the hydrogels triggered by other metals such Fe 3+ , Co 2+ , Ni 2+ , and so on. Moreover, the obtained hydrogels exhibit high transparency (∼93.8%), excellent conductivity, and self-healing properties. The multifunctional hydrogels triggered by a simple yet effective self-catalysis strategy could find important applications in soft machines, sensing, and the inscription of information.
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