Journal of Physical Chemistry C
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2022
·
IF 4.177
Yuemiao Lai,Zhengtian Pu,Peng Liu,Fangliang Li,Jie Zeng,Xueming Yang,Qing Guo
The low-temperature C–H bond activation of alkanes remains a big challenge in alkane dehydrogenation. In this work, ethylbenzene (EB) oxidative dehydrogenation has been investigated on rutile(R)-TiO2(110) under both ultrahigh vacuum (UHV) and ambient conditions. Under UHV conditions, styrene is produced with nearly 100% selectivity in a stepwise manner, in which the first C–H bond dissociation of EB occurs at <285 K with the help of surface O22– species, followed by the second C–H bond dissociation at about 400 K. However, styrene, acetophenone, and 2,3-diphenylbutane products are produced from EB oxidative dehydrogenation under ambient conditions, suggesting that α-H dissociation is the initial step of EB oxidative dehydrogenation. This may be also possible for EB oxidative dehydrogenation on R-TiO2(110) under UHV conditions. The different pathways of EB oxidative dehydrogenation under UHV and ambient conditions may originate from different intermediates and O2 concentrations. This work provides new insight into the fundamental understandings of the low-temperature C–H bond activation of alkyl chains of aromatic hydrocarbons, which may promote the development of new catalysts for efficient styrene production from EB oxidative dehydrogenation under mild conditions.
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RENEWABLE ENERGY
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2021
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IF 8.001
Feng Lin,Yulong Ma,Yonggang Sun,Kanghe Zhao,Tingting Gao,Yingbo Zhu
Due to the inertness and structural complexity of lignin, upgrading lignin to biofuels and fine chemicals still faces great challenges. In this paper, a one-pot method was used to catalyze straw lignin with H-ZSM-5 supported by Ni and Ru bimetals, and the lignin conversion rate reached 88.1%. The yield of monophenol was 19.5%, of which the yield of 4-ethylphenol and 4-ethylguaiacol was 4.9% and 3.8%, respectively. The 2D HSQC NMR analysis confirmed that the Ni–Ru/H-ZSM-5 catalyst had an obvious activity of breaking C β -O bonds before and after the reaction. The result showed that after loading metal Ni and Ru, the Lewis acid of the catalytic system was greatly increased, which caused electron transfer between Ni and Ru. 3Ni-1.5Ru/H-ZSM-5 had the strongest activity due to the largest synergy among Ni, Ru and H-ZSM-5. The synergy was the key factor leading to the cleavage of C–C and C–O bonds in straw lignin and the high-performance catalytic degradation of lignin. Besides, the effect of reaction solvent and hydrogen resource on upgrading lignin to fine chemicals over 3Ni-1.5Ru/HZSM-5 catalyst was also intensively investigated. This research developed a method for the direct conversion of lignin into valuable monophenols.
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MEASUREMENT SCIENCE and TECHNOLOGY
·
2021
·Vol. 32
·期 9
·095114
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IF 2.046
Qianchun Zhang,Yan Wang,Qin Zhou,Yafei Chen,Yuguo Zheng,Shan Tang,Yuxian Zhao,Li Jiang
Nonmetallic nanocatalysts have demonstrated powerful potential in cataluminescence (CTL) sensing fields. In this study, an original method for the fabrication of a CTL gas sensor was developed to detect acetylacetone based on nanosized hexagonal boron nitride (h-BN). The luminescence characteristics and optimum operating temperature, wavelength, and carrier gas flow rate parameters for the h-BN sensor were studied in detail. Compared with other common gases (such as cyclohexanone, acetaldehyde, and acetone), the fabricated sensor demonstrated a high selectivity and sensitivity toward acetylacetone. This was verified by density functional theory calculations, which were consistent with the experimental results. The CTL intensity and concentration of acetylacetone had a linear relationship in the range of 0.050–20 μg ml−1 (r = 0.9989) with a low detection limit of 16 ng ml−1 (S/N = 3). The developed sensor was applied to analyze spiked samples, and satisfactory recoveries for acetylacetone of 82.2%–118% were obtained with excellent reproducibility (2.8%–11%). These results indicated that the system has excellent sensing properties including a high selectivity, sensitivity, and stability, proving its broad application prospects for detecting acetylacetone.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2021
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IF 8.128
Zhao Du,Lang Feng,Zhonglu Guo,Tongqi Yan,Qi Hu,Jing Lin,Yang Huang,Chengchun Tang,Yi Fang
Herein, a series of ultrathin h-BN/Bi 2 MoO 6 heterojunction with excellent photocatalytic activity has been firstly prepared via a feasible solvothermal method . Our results suggest that the optimized photocatalyst possesses a high degradation ratio of tetracycline (TC), oxytetracycline (OTC) and doxycycline (DC) up to 99.19%, 95.28% and 91.04% under visible-light irradiation, respectively. We highlight that the outstanding photocatalytic activity is mainly attributed to the prominent performance of tetracycline adsorption on h-BN and the dominant visible-light absorption by Bi 2 MoO 6 as well as the effective photogenerated carrier separation induced by the synergetic effect between h-BN and Bi 2 MoO 6 . Moreover, DFT calculations reveal that the built-in electric field formed between h-BN and Bi 2 MoO 6 gives rise to the separation of carriers and the polarization of tetracycline molecules. Last but not the least, the specific process and micro-mechanism of the photocatalytic tetracycline degradation under visible-light driven have also been illuminated. The present work pioneers the application of ultrathin h-BN/Bi 2 MoO 6 heterojunction as a novel tetracycline degradation photocatalyst and further guides the design of more visible-light photocatalysts.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2019
·Vol. 125
·期 2
·1-10
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IF 1.784
Chai Chen,Liu Jianxin,Wang Yawen,Zhang Xiaochao,Duan Donghong,Fan Caimei,Wang Yunfang
A h-WO 3 decorated Ag–AgCl composite was prepared through facile precipitation and photoreduction methods and demonstrated to be a highly efficient and stable photocatalyst for the degradation of Rhodamine B (RhB) under visible light. Ag–AgCl/h-WO 3 exhibited much improved photocatalytic performance was elucidated from the physical–chemical properties of AgCl and h-WO 3 and the surface plasmon resonance effect of the Ag particles. The techniques of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectrometry (XPS) and photocurrent were used to characterize crystalline phases, morphology, composition and separation efficiency between electrons (e − ) and holes (h + ) of the synthesized composite photocatalyst. XPS results confirmed the existence of W 5+ and W 6+ on the surface of h-WO 3 sample, which favored electrons transfer between AgCl and Ag, and generated superoxide radical for the degradation of RhB. The active species trapping experiments results further demonstrated that the formation of superoxide radical during the system. Finally, the underlying photocatalytic mechanism for the removal of RhB by Ag–AgCl/h-WO 3 composite was examined.
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DYES AND PIGMENTS
·
2019
·
IF 4.018
Yanhong Wu,Minhua Su,Jiawei Chen,Zuopeng Xu,Jiafeng Tang,Xiangyang Chang,Diyun Chen
A batch equilibrium system was used in this study to investigate the adsorption of methyl orange (MO) on hollow molybdenum disulfide (h-MoS 2 ) microspheres . The effects of experimental conditions, such as the initial concentration, agitation time, solution pH and temperature, on the adsorption were examined. The adsorption of MO on h-MoS 2 microspheres was unexpectedly ultrafast. Adsorption equilibrium was rapidly achieved in 10 seconds, and the maximum adsorption capacity for MO was 41.52 mg/g. The Langmuir and Freundlich models were used for determining the adsorption parameters. The results reveal that the Freundlich model fits well with the experimental adsorption data. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were applied to determine the kinetics of MO ultrafast adsorption. The obtained results indicate that the experimental kinetics data of h-MoS 2 microspheres are well explained by the second-order model. The obtained values of the thermodynamic parameters (Δ H 0 , Δ S 0 , and Δ G 0 ) indicated that MO adsorption on h-MoS 2 microspheres was an exothermic and spontaneous process. The thermodynamic parameters also confirmed that the MO adsorption is a chemical and physical adsorption process on the surfaces of h-MoS 2 microspheres. The adsorption mechanism was further advanced by FT-IR. The findings of this study open an avenue for applying h-MoS 2 microspheres for organic dyes removal from industrial wastewater streams.
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Catalysis Science & Technology
·
2024
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IF 4.4
Ling Ding,Lou Gao,Di Pan,Ke Du,Jiayu Yu,Wanyi Li,Yahong Zhang,Yi Tang
The utilization of racemic lactic acid (rac-LA) produced via chemocatalytic conversion for polylactic acid (PLA) synthesis remains limited due to the formation of undesired mesomeric lactide (meso-LD), a by-product that arises during the conversion process. This study proposes the use of shape-selective H-Beta zeolite to reduce the formation of meso-LD in lactide (LD) by leveraging its selectivity towards different lactic dimers (L2A) in a one-step catalytic conversion of rac-LA to LD. Experimental results from various LA solutions with different L2A content indicate that the L2A content is critical for maximizing the selectivity of racemic lactide (D/L-LD), thus confirming the shape-selective nature of H-Beta zeolite towards L2A. Additionally, it is found that increasing the reaction temperature and employing structurally reconstructed H-Beta zeolite with more regularized channels as a catalyst can further decrease meso-LD formation, and a LD yield of 60% with a D/L-LD/meso-LD ratio of 2.26 can be achieved under optimal catalyst and reaction conditions. Despite the coexistence of D/L-LD and meso-LD in the final product, this study marks a significant step towards controlling the stereoisomer distribution of LD synthesized from rac-LA derived from chemical conversion.
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ChemistrySelect
·
2025
·Vol. 10
·期 7
·e202405464
·
IF 2
Kun Jia,Peng Jia
Graphical The asymmetric activation of anhydrous methanol molecules is realized by exogenous protons, the position and protonation position of asymmetric activation are determined, and the C─H bonding energy and reaction activation energy of some methanol molecules are reduced, and the asymmetric regulation of the non-oxidation dehydrogenation reaction process of anhydrous methanol molecules was realized. The activation of C─H bonds under mild conditions is a crucial step in the conversion of organic molecules. However, the simultaneous activation of C─H bonds in methanol can result in excessive oxidation, thereby diminishing the selectivity for formaldehyde production. We achieved selective activation of the C─H bonds in methanol under mild conditions by adjusting the proton concentration in an anhydrous methanol solution, which significantly enhanced the dehydrogenation rate of methanol. Additionally, we constructed related molecular models to identify the sites of asymmetric oxidation, providing new insights for further studies on C─H bond activation.
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JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Jiami Ma,Zhixin Hu,Weihong Guo,Cheng Ni,Pan Li,Bosheng Chen,Songhua Chen,Jinlong Wang,Yanbing Guo
Ground−level ozone (O 3 ) pollution poses a significant threat to both ecosystem sustainability and human health. The catalytic decomposition of O 3 presents as a promising technology to address the issues of O 3 pollution. This study undertook the synthesis of various functionalized metal−organic framework (MOF) catalysts ( i.e., X-MIL-53(Fe) (X = H, NH 2 , NO 3 )) to delve into the influence of ligand functional groups on skeletal structure and catalytic efficacy, particularly focusing on unraveling the mechanism of O 3 catalytic decomposition under humid conditions. NH 2 -MIL-53(Fe) catalyst achieved complete O 3 decomposition under ambient temperature and high humidity conditions (RH=75 %), exhibiting a reaction rates (mol·m −2 ·s −1 ) 129 and 10.5 times greater than that of MIL-53(Fe) and NO 2 -MIL-53(Fe). The NH 2 group promotes electron flow within the backbone towards the hydroxyl group (OH) linked to Fe atom. In humid O 3 , H 2 O molecules augment the interaction between O 3 and NH 2 -MIL-53(Fe), and OH is converted to·O 2 − after deprotonation, promoting O 3 decomposition. Additionally, leveraging three−dimensional (3D) printing technology, a monolithic catalyst for O 3 decomposition was prepared for application. This study not only advances understanding of the mechanisms underlying O 3 decomposition but also offers practical solutions for addressing O 3 pollution at humid conditions.
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EUROPEAN POLYMER JOURNAL
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2020
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IF 3.862
Yuejia Zhu,Yongzhu Hu,Zhenjiang Li,Bo Liu,Yuanyuan Qu,Zhihao Zhang,Tianfo Guo,Yongqiang Li,Luoyu Gao,Kai Guo
Hydrogen bond donor (HBD) and organic base binary cocatalyst established a gold standard in organocatalytic ring-opening polymerizations (ROPs). In depth probe of the mechanisms revealed that proton abstraction of the acidic H on the HBDs by the bases do occur frequently. A truly simple HBD and Lewis base (LB) cocatalysis, however, was elusive. We proposed genuine HBD/LB cocatalyst for ROPs by introducing 3-amino-1,2,4-benzothiadiazine-1,1-dioxide (ABTD) as a bidentate H-bond donor and triethylamine (TEA) as a mild Lewis base. ROPs of lactide (LA) and trimethylene carbonate (TMC) in solutions at room temperature were success. The mild ROPs produced polylactide (PLA) of predictable molecular weights (from 1.6 to 26.7 kg mol −1 ) and extremely narrow dispersities (Đ 1.01 to 1.06). Furthermore, well-defined diblock copolymers PTMC-b-PLA were synthesized. NMR titration experiments verified exclusive H-bond donor activation of the monomer and TEA activation of the hydroxyl chain end without trace of proton abstraction.
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ORGANOMETALLICS
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2020
·
IF 3.804
Liangwei Zhang,Long Liu,Tianzeng Huang,Qizhi Dong,Tieqiao Chen
A palladium-catalyzed cyclobutanation of aryl sulfonates with strained alkenes has been developed. The methodology is featured to achieve the cleavage of both C–O and C–H bonds of phenol derivatives in one pot. Under the reaction conditions, in addition to reactive triflates, the relatively inactive tosylates and mesylates can also be transformed into the corresponding benzocyclobutanes in high yields. This reaction can be carried out in gram-scale experiments with a low loading of the palladium catalyst and is applicable to the cyclobutanative modification of bioactive molecules, highlighting its synthetic value in organic synthesis.
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PROGRESS IN ORGANIC COATINGS
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2021
·
IF 5.161
Beibei Chen,Zhe Dong,Jiaye Li,Mengjie Zhang,Kan Zhang
Hexagonal boron nitride (h-BN) is a promising additive used in tribology ; however, its application is limited due to its poor interfacial combination with polymer matrices induced by its inert and smooth surface. In order to tackle this problem, an innovative ZnO nanowires-decorated h-BN hybrid was first prepared, which was then applied onto epoxy (EP) to enhance its tribological properties. The results demonstrated that ZnO nanowires were in-situ grown uniformly on the exterior of the hydroxylated h-BN, which strengthened the physical and chemical interaction between h-BN and EP, since the EP chains were prone to wrap around the ZnO nanowires. When the h-BN/ZnO content was 0.5 wt%, the friction coefficient and wear rate were decreased by 81.5% and 95.4%, respectively, and the corresponding composite coating possessed superior tribological properties under harsh conditions, which was mainly because of the synergistic reinforcing and lubricating effect between the ZnO nanowires and h-BN, as well as the good interfacial compatibility between h-BN/ZnO hybrid and EP. Moreover, the corresponding enhancement mechanisms of h-BN/ZnO were proposed.
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