ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2023
·
IF 11.4
Yingying Zhou,Jia-jia Jiao,Huang Huang,Yong Dong Liu,Rugang Zhong,Xin Yang
Dichloroacetonitrile (DCAN) as one of the potentially prioritized regulated DBPs has drawn great attention; however, understanding its formation, especially the C–C bond cleavage mechanisms, is limited. In this study, DCAN formation mechanisms from long-chain primary amines, amino acids, and dipeptides during chlorination were investigated by a combined computational and experimental approach. The results indicate that nitriles initially generate for all of the above precursors, then they undergo β-C-hydroxylation or/and α-C-chlorination processes, and finally, DCAN is produced through the Cα–Cβ bond cleavage. For the first time, the underlying mechanism of the C–C bond cleavage was unraveled to be electron transfer from the O– anion into its attached C atom in the chlorinated nitriles, leading to the strongly polarized Cα–Cβ bond heterocleavage and DCAN– formation. Moreover, DCAN molar yields of precursors studied in the present work were found to be determined by their groups at the γ-site of the amino group, where the carbonyl group including −CO2–, −COR, and −CONHR, the aromatic group, and the −OH group can all dramatically facilitate DCAN formation by skipping over or promoting the time-consuming β-C-hydroxylation process and featuring relatively lower activation free energies in the C–C bond cleavage. Importantly, 4-amino-2-hydroxybutyric acid was revealed to possess the highest DCAN yield among all the known aliphatic long-chain precursors to date during chlorination. Additionally, enonitriles, (chloro-)isocyanates, and nitriles can be generated during DCAN formation and should be of concern due to their high toxicities.
研究领域:
环境化学
·
水处理
·
毒理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2022
·
IF 6.364
Zhenxiao Tang,Maozhong Yi,Huan Yin,Yuhui Du,Huang Wu,Ke Peng
A C/C-ZrC-SiC composite was successfully prepared by high-solid-loading slurry impregnation combined with polymer infiltration and pyrolysis. The microstructure and ablation behavior of the C/C–ZrC–SiC composite were investigated. ZrC particles were uniformly distributed in the matrix, and the obtained C/C–ZrC–SiC composite had a high density of 2.74 g/cm 3 . After exposure to oxyacetylene flame with a heat flux of 3.86 MW/m 2 for 120 s, the mass and linear ablation rates of the composite were 0.72 ± 0.11 mg/s and 0.52 ± 0.09 µm/s, respectively. The excellent ablation properties of the composite were attributed to the protection of the matrix by a three-layered oxide scale consisting of ZrO 2 /SiO 2 -rich/ZrO 2 -SiO 2 .
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Ze Zhang,Cunqian Fang,Yuanqi Weng,Xiao Luo,Qizhong Huang,Huiping Hu
Graphene was introduced into C/C–SiC composites via pressureless impregnation to enhance the mechanical and thermal properties of the composites. The effects of various graphene contents on the mechanical and ablative performances of C/C–SiC composites were investigated. The results showed that the ultimate bending stress and compressive stress of the C/C–SiC composites increased by 28.98% and 23.64%, respectively, after adding 7.25% graphene. Moreover, the ablation rates of the composites were vastly decreased after adding a slight graphene content (2.13%). However, the ablation rates increased with increasing of graphene content, indicating that the benefit of introducing graphene on the ablation property decreased, which was mainly ascribed to the relative reduction in the SiC content. As a result, introducing slight graphene into C/C–SiC composites had the greatest benefit on the anti-ablation performance.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Omega
·
2020
·
IF 2.87
Zhenghong Zhou,Kangfei Hu,Jiawei Wang,Zhibin Li,Yan Zhang,Zhenggen Zha,Zhiyong Wang
An electrochemical synthesis for quinazolines and quinazolinones was developed via a C(sp3)-H amination/C-N cleavage by virtue of the anodic oxidation. The reaction can be carried out in aqueous media under mild conditions to afford the desired products with high yields. The reaction mechanism was proposed after detailed investigation.
研究领域:
有机化学
·
电化学
✓ 已验证
DOI
高影响因子
Reaction Kinetics Mechanisms and Catalysis
·
2024
·Vol. 137
·期 4
·1911-1925
·
IF 1.7
Song Linyan,Nie Genkuo,Chen Xiulei,Wang Hongyu,Liu Shiwei,Yu Hailong,Liu Xuguang,Yang Guihua,Yu Shitao
The multifunctional groups of 5-hydroxymethylfurfural (5-HMF) make it could extend carbon chain by different C–C coupling reactions and extensively applied in the bio-jet fuel synthesis. Herein, one-pot reaction of lignocellulose derived chemicals with 5-HMF was studied by experimental and density functional theory (DFT) methods. The kinetic models of products were established and the apparent activation energies of the products by C–C coupling reaction of phenol, anisole, guaiacol, cyclohexanone and acetone with 5-HMF on Hβ were 95.3 kJ/mol, 104.8 kJ/mol, 90.4 kJ/mol, 90.0 kJ/mol and 112.2 kJ/mol, indicating these reactions centering on 5-HMF competitive intensively. Then the effects of the catalysis were analyzed by applying commercial catalysis to the mixed coupling reaction of 5-HMF. It was found that Brønsted acid is more favorable to alkylation reaction, and Lewis acid is more beneficial to aldol condensation reaction. By Fukui function, due to the nucleophilic index of cyclohexanone (2.74 eV) is higher than that (2.48 eV) of acetone, and the Mulliken electronegativity (3.43 eV) is weaker than that (3.55 eV) of acetone, cyclohexanone is more conducive than acetone to the aldol condensation reaction. This work provides data reference for product regulation in the bio-jet fuel synthesis.
研究领域:
化学工程
·
可再生资源
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of the American Chemical Society
·
2024
·
IF 14.4
Ernest Pahuyo Delmo,Yian Wang,Yihua Song,Shangqian Zhu,Haichuan Zhang,Hongming Xu,Tiehuai Li,Juhee Jang,Yongjun Kwon,Yinuo Wang,Minhua Shao
The reaction mechanism of CO2 electroreduction on oxide-derived copper has not yet been unraveled even though high C2+ Faradaic efficiencies are commonly observed on these surfaces. In this study, we aim to explore the effects of copper anodization on the adsorption of various CO2RR intermediates using in situ surface-enhanced infrared absorption spectroscopy (SEIRAS) on metallic and mildly anodized copper thin films. The in situ SEIRAS results show that the preoxidation process can significantly improve the overall CO2 reduction activity by (1) enhancing CO2 activation, (2) increasing CO uptake, and (3) promoting C–C coupling. First, the strong *COO– redshift indicates that the preoxidation process significantly enhances the first elementary step of CO2 adsorption and activation. The rapid uptake of adsorbed *COatop also illustrates how a high *CO coverage can be achieved in oxide-derived copper electrocatalysts. Finally, for the first time, we observed the formation of the *COCHO dimer on the anodized copper thin film. Using DFT calculations, we show how the presence of subsurface oxygen within the Cu lattice can improve the thermodynamics of C2 product formation via the coupling of adsorbed *CO and *CHO intermediates. This study advances our understanding of the role of surface and subsurface conditions in improving the catalytic reaction kinetics and product selectivity of CO2 reduction.
研究领域:
材料科学
·
电化学
·
催化反应
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Cuiyan Li,Siyi Qi,Haibo Ouyang,Tianzhan Shen,Zihao Chen,Yanlei Li,Jiaqi Liu
To develop active thermal protection for ultra-high temperature ceramics, C/C-ZrC-CuNi composites were fabricated using a PIP method. This study systematically studied the influence of CuNi alloy content on the microstructure, mechanical properties, thermal conductivity, and ablation resistance of the composites. The incorporation of CuNi alloy significantly enhanced the sintering of the ZrC-C matrix, resulting in improved densification of the composites. Furthermore, the presence of CuNi alloy promoted the graphitization of the carbon matrix, thereby enhancing the thermal conductivity. The composites with the highest CuNi alloy content (ZCN4 sample) exhibited the greatest density（2.26 g/cm 3 ） and thermal conductivity（32.3 W/m·k）, along with superior ablation resistance, with mass and line ablation rates of 2.09 mg/s and 2.06 μm/s. This enhanced ablation resistance can be primarily attributed to the sweating cooling effect of the CuNi alloy, which effectively reduces the ablation temperature. Additionally, the formation of Cu 2 O and NiO during ablation acts as sintering aids, facilitating the development of a compact ZrO 2 scale that resists flame erosion. The increased thermal conductivity of the composite further mitigates the temperature rise on the ablation surface.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
GREEN CHEMISTRY
·
2020
·Vol. 22
·期 8
·2468-2473
·
IF 9.48
Taimei Cai,Qiang Deng,Hailong Peng,Jin Zhong,Rui Gao,Jun Wang,Zheling Zeng,Ji-Jun Zou,Shuguang Deng
The major challenge in the synthesis of high-density biofuels is to identify the bio-based source for C–C cyclic compounds and C–C coupling reactions with a suitable selectivity. Herein, we selectively synthesize 1,2,4-benzenetriol (BTO) with a yield of 51.4% from cellulose-derived 5-hydromethylfurfural via a ring-rearrangement reaction. The cellulose-derived route is a more meaningful route for the C–C cyclic compounds compared to the traditional hemicellulose- and lignin-derived routes. Furthermore, BTO is very easily dimerized via a C–C oxidative coupling reaction, showing a yield of 94.4% and selectivity of nearly 100% under environmentally friendly reaction conditions. After hydrodeoxygenation, bicyclohexane is obtained with a yield of 87.4%. This work not only provides a promising route to produce C–C cyclic fine compounds based on a cellulose-derived route, but also shows a highly efficient synthesis route for high-density biofuels via the C–C oxidative coupling reaction.
研究领域:
化学工程
·
可再生能源
·
合成化学
✓ 已验证
产品关联
DOI
高影响因子
GREEN CHEMISTRY
·
2015
·Vol. 17
·期 11
·4968-4973
·
IF 8.02
Yangyang Ma,Zhongtian Du,Junxia Liu,Fei Xia,Jie Xu
Selective transformation of lignin into value-added aromatics is highly attractive and rather challenging. Catalytic oxidative degradation provides a promising approach to obtain aromatics from lignin while preserving the benzene units. In this study, vanadium-catalyzed aerobic oxidation of 2-phenoxy-1-phenylethanol was studied as a lignin model compound. The solvent played a significant role in the distribution of oxidation products. In the presence of acetic acid, oxidative C–C bond cleavage was preferred, while oxidation products via C–H bond cleavage were rather limited. A one-electron transfer process was involved in the oxidation reaction. The occurrence of vanadium(V) was detected, and the carboxylic group could coordinate to vanadium(V) through exchange with the acetylacetonato ligand during oxidation in the presence of acetic acid.
研究领域:
化学
·
催化科学
✓ 已验证
DOI
高影响因子
ACS Omega
·
2019
·
IF 2.584
Jing Wang,Aisen Li,Shuping Xu,Chongping Song,Yijia Geng,Ling Ye,Houyu Zhang,Weiqing Xu
The mixed π–π packing of the donor (D) and acceptor (A) molecules is the highlighting feature of the intermolecular interactions following charge transfer (CT) issues in organic cocrystal systems. There is an inverse relationship between the D–A interplanar distance and the intermolecular CT interaction. However, the D–A C–C surface close contact (relative areas) on the intermolecular CT interactions in organic cocrystal systems is rarely investigated. Herein, we designed and constructed a novel cocrystal and its solvate cocrystal. The structural and electrostatic potential analyses suggest that the solvation destroys the N–H···N hydrogen bond interaction between phenothiazine (PTZ) and 1,2,4,5-tetracyanobenzene (TCNB), which causes the TCNB molecules to have a 90° rotation along the normal axis of the PTZ plane. Thus, the D–A C–C surface close contact is enlarged, strengthening the intermolecular π–π stacking interactions and intermolecular CT interaction between PTZ and TCNB, which are further evidenced by the absorption and Raman spectroscopic analyses. This study provides rare evidence of the enlarged C–C surface close contact in the mixed packing between D and A that greatly contributes to the intermolecular CT interaction in a D–A cocrystal system. It also provides a deeper understanding of the role of solvation in the structure–property relationship of organic cocrystal materials.
研究领域:
材料科学
·
物理化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Scientific Reports
·
2017
·Vol. 7
·期 1
·1-10
·
IF 4.259
Feng Shanglei,Yang Yingguo,Li Li,Zhang Dongsheng,Yang Xinmei,Xia Huihao,Yan Long,Tsang Derek K. L.,Huai Ping,Zhou Xingtai
An in-situ real-time synchrotron-based grazing incidence X-ray diffraction was systematically used to investigate the crystal structural evolution of carbon fiber reinforced carbon matrix (C/C) composite impregnated with FLiNaK molten salt during the heat-treatment process. It was found that the crystallographic thermal expansion and contraction rate of interlayer spacing d
002 in C/C composite with FLiNaK salt impregnation is smaller than that in the virgin sample, indicating the suppression on interlayer spacing from FLiNaK salt impregnated. Meanwhile the crystallite size L
C002 of C/C composite with FLiNaK salt impregnation is larger than the virgin one after whole heat treatment process, indicating that FLiNaK salt impregnation could facilitate the crystallization of C/C composite after heat treatment process. This improved crystallization in C/C composite with FLiNaK salt impregnation suggests the synthetic action of the salt squeeze effect on crooked carbon layer and the release of internal residual stress after heating-cooling process. Thus, the present study not only contribute to reveal the interaction mechanism between C/C composite and FLiNaK salt in high temperature environment, but also promote the design of safer and more reliable C/C composite materials for the next generation molten salt reactor.
研究领域:
材料科学
·
核能工程
·
晶体学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Ran Wang,Zhiding Zheng,Zhuo Li,Xiaoxiang Xu
Photocatalytic C-C coupling is a green and sustainable route to produce value-added chemicals. However, the product selectivity is generally non-tunable and there is a lack of an in-depth understanding of the dependence of product selectivity on the band structure of the semiconductor photocatalyst. Here, Zn x Cd 1-x S solid solutions have been explored for photocatalytic C-C coupling using benzyl alcohol as a typical reactant. The conversion rate of benzyl alcohol and selectivity of C-C coupling products is inherently linked to the solid solution level of Zn x Cd 1-x S which can be readily tuned. An optimal solid solution level has been found at Zn 0.6 Cd 0.4 S (x = 0.6) which delivers a conversion rate of 91.61% and a selectivity of 98.83% for C-C coupling products. These findings not only deepen the understanding on factors that affect product selectivity but also justify the usefulness of solid solutions in tuning the C-C coupling reactions.
研究领域:
催化化学
·
材料科学
·
环境科学
✓ 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）