Journal of Environmental Chemical Engineering
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2024
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IF 7.4
Xiaoting Xing,Wenlong Cao,Jinliang Yan,Yuchun Zhang,Payam Ghorbannezhad,Zhiyu Li,Peng Fu
Cyclohexanol is a crucial intermediate in the synthesis of nylon and other chemical industry materials. However, directly hydrogenating phenol to cyclohexanol presents challenges, including harsh reaction conditions and low selectivity for the desired product. To address these issues, a two-step method was proposed, involving the mild catalytic decoupling and hydrogenation of lignin, which enables the efficient production of cyclohexanol. Lignin was initially depolymerized into 18.08 % phenol and 60.63 % guaiacol in a dilute alkaline aqueous solution at 200°C under atmospheric nitrogen. Subsequently, the effects of catalytic hydrogenation of phenol in different solvents were examined. When water was used as the solvent, phenol conversion reached 100 % within 2 hours at 30°C, with a selectivity of 94.69 % to cyclohexanol. The hydrogenation process, catalyzed by 5 wt% Pd/AC, was studied under these conditions. It was found that phenol was first partially hydrogenated to cyclohexenol, which quickly isomerized to cyclohexanone and was further hydrogenated to cyclohexanol. The two steps create a low-temperature and low-pressure pathway for efficiently converting lignin to cyclohexanol, thereby enhancing lignin's potential value.
研究领域:
化学工程
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生物质转化
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催化科学
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DOI
高影响因子
ChemSusChem
·
2023
·Vol. 16
·期 12
·e202300208
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IF 8.4
Daihong Gao,Denghao Ouyang,Yuchen Bai,Xuebing Zhao
Graphical New antioxidants were prepared by oxidative depolymerization of lignin followed by aldol condensation to form conjugated structure with benzene ring. Kinetics of aldol condensation between lignin-derived aromatic aldehydes and methyl ethyl ketone was investigated. The increase in the antioxidation ability was confirmed by experimentation and interpreted by density functional theoretical calculation. Novel antioxidants are synthesized by CuSO 4 -catalyzed oxidative depolymerization of lignin to form aromatic aldehydes followed by aldol condensation with methyl ethyl ketone (MEK). Aldol condensation greatly improves the antioxidation ability of lignin depolymerized products. Three lignin monomeric aromatic aldehydes, – p -hydroxybenzaldehyde, vanillin, and syringaldehyde – are further employed for aldol condensation with MEK, resulting in successful synthesis of new antioxidants 1-(4-hydroxyphenyl)pent-1-en-3-one (HPPEO), 1-(4-hydroxy-3-methoxyphenyl)pent-1-en-3-one (HMPPEO), and 1-(4-hydroxy-3,5-dimethoxyphenyl)pent-1-en-3-one (HDMPPEO), respectively. Kinetic modeling illustrates that p -hydroxybenzaldehyde has the highest rate of reaction with MEK, followed by vanillin and then syringaldehyde, which is probably affected by the presence of methoxy groups. The syringaldehyde-derived product (HDMPPEO) displays the best antioxidation ability. As revealed by density functional theory calculations, electron-donating groups, such as methoxy, and conjugated side chains effectively improve the antioxidation ability. A hydrogen atom transfer (HAT) mechanism tends to occur in nonpolar solvents, whereas a sequential proton-loss electron transfer (SPLET) mechanism is favored in polar solvents. This work thus can inspire new pathways for valorization of lignin to produce high value-added products.
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
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2019
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IF 4.784
Junwang Zhang,Lili Song,Kunlan Li,Qingda An,Hao Ma,Liyu Yang,Ligang Wei
Water addition was found to enhance the thermal stability of alkylimidazolium–acetate ionic liquids (ILs). Especially in the case of high water content (30–50 wt%), few decomposition products can be observed in the 1 H NMR spectra even after treatment for 24 h at 150 °C. On the basis of this finding, lignin treatment of water and acetate IL mixtures (50–90 wt% IL content) were investigated at 150 °C. The addition of water, as opposed to pure IL treatment, can inhibit the lignin depolymerization into small fragments. Lignin degradation and the structure of regenerated lignin are more affected by cation types of ILs rather than the IL contents and pH values. In the case of 50–70 wt% 1-ethyl-3-methylimidazolium acetate–water system, the specific inter-unit linkages of lignin can be broken down, and regenerated lignin with a narrow polydispersity index (5.0–9.6) can be obtained.
研究领域:
绿色化学
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生物质转化
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高分子化学
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离子液体化学
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木质素化学
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可持续材料
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热化学转化
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DOI
高影响因子
Frontiers in Microbiology
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2023
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IF 5.2
Tang Miran,Huang Zeyu,Zhang Xiaodong,Kong Jingchun,Zhou Beibei,Han Yijia,Zhang Yi,Chen Lijiang,Zhou Tieli
Introduction: Phage is promising for the treatment of hypervirulent Klebsiella pneumoniae (hvKP) infections. Although phage resistance seems inevitable, we found that there still was optimization space in phage therapy for hvKP infection.Methods: The clinical isolate K. pneumoniae FK1979 was used to recover the lysis phage ΦFK1979 from hospital sewage. Phage-resistant bacteria were obtained on LB agar and used to isolate phages from sewage. The plaque assay, transmission electron microscopy (TEM), multiplicity of infection test, one-step growth curve assay, and genome analysis were performed to characterize the phages. Colony morphology, precipitation test and scanning electron microscope were used to characterize the bacteria. The absorption test, spot test and efficiency of plating (EOP) assay were used to identify the sensitivity of bacteria to phages. Whole genome sequencing (WGS) was used to identify gene mutations of phage-resistant bacteria. The gene expression levels were detected by RT-qPCR. Genes knockout and complementation of the mutant genes were performed. The change of capsules was detected by capsule quantification and TEM. The growth kinetics, serum resistance, biofilm formation, adhesion and invasion to A549 and RAW 264.7 cells, as well as G. mellonella and mice infection models, were used to evaluate the fitness and virulence of bacteria.Results and discussion: Here, we demonstrated that K2 capsule type sequence type 86 hvKP FK1979, one of the main pandemic lineages of hvKP with thick capsule, rapidly developed resistance to a K2-specific lysis phage ΦFK1979 which was well-studied in this work to possess polysaccharide depolymerase. The phage-resistant mutants showed a marked decrease in capsule expression. WGS revealed single nucleotide polymorphism (SNP) in genes encoding RfaH, galU, sugar glycosyltransferase, and polysaccharide deacetylase family protein in the mutants. RfaH and galU were further identified as being required for capsule production and phage sensitivity. Expressions of genes involved in the biosynthesis or regulation of capsule and/or lipopolysaccharide significantly decreased in the mutants. Despite the rapid and frequent development of phage resistance being a disadvantage, the attenuation of virulence and fitness in vitro and in vivo indicated that phage-resistant mutants of hvKP were more susceptible to the immunity system. Interestingly, the newly isolated phages targeting mutants changed significantly in their plaque and virus particle morphology. Their genomes were much larger than and significantly different from that of ΦFK1979. They possessed much more functional proteins and strikingly broader host spectrums than ΦFK1979. Our study suggests that K2-specific phage has the potential to function as an antivirulence agent, or a part of phage cocktails combined with phages targeting phage-resistant bacteria, against hvKP-relevant infections.
研究领域:
微生物学
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分子生物学
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传染病学
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基因组学
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噬菌体疗法
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DOI
PubMed
高影响因子
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