Polymers
·
2023
·Vol. 15
·期 8
·1932
·
IF 5
Liang Yu,Ziwei Li,Chen Hua,Kaimin Chen,Xuhong Guo
Metal nanoparticles are widely used in catalysis. Loading metal nanoparticles into polymer brushes has aroused wide attention, but regulation of catalytic performance still needs to be improved. The novel diblock polymer brushes, polystyrene@sodium polystyrene sulfonate-b-poly (N-isopropylacrylamide) (PSV@PSS-b-PNIPA) and PSV@PNIPA-b-PSS with reversed block sequence, were prepared by surface initiated photoiniferter-mediated polymerization (SI-PIMP) and used as nanoreactors to load silver nanoparticles (AgNPs). The block sequence caused the difference of conformation and further affected the catalytic performance. PSV@PNIPA-b-PSS@Ag was found to be able to control the amount of AgNPs exposed to external reactant of 4-nitrophenol at different temperatures to achieve regulation of the reaction rate due to the hydrogen bonds and further physical crosslinking between PNIPA and PSS.Keywords:diblock polymer brush;temperature response;hydrogen bond;silver catalyst
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CATALYSIS
·
2018
·
IF 6.759
Kairui Liu,Peifang Yan,Hong Jiang,Zhi Xia,Zhanwei Xu,Shi Bai,Z. Conrad Zhang
Selective hydrocleavage of aromatic C O bond while preserving the aromatic ring is a desired catalytic process in hydrodeoxygenation (HDO) of biomass derived aromatic oxygenates to high value biochemicals. Guaiacol with typical methoxy and phenolic hydroxyl groups is a representative aromatic di-oxygenates of lignin fragments. Sub-nanometer sized silver, a poor hydrogenation metal catalyst, was found to initiate H 2 dissociation and H spillover onto anatase TiO 2 (TiO 2 -A) surface. The spillover hydrogen enhanced the partial reduction of TiO 2 -A surface at a substantially lowered temperature as compared to the reduction of TiO 2 -A by molecular H 2 . The reduction of TiO 2 -A surface by spillover hydrogen was enhanced at Ag loading as low as 0.01 wt% on TiO 2 -A. The ratio of spillover H to Ag was as high as 675 at Ag loading of 0.01 wt% and the ratio decreased with increasing Ag loading. We found that the yield of phenolic products was linearly correlated with the amount of spillover hydrogen that created oxygen vacancy (Ov) through partial reduction of TiO 2 -A surface. Methanol was formed as the main side-product, indicating that the direct hydrocleavage of aromatic C-OCH 3 in guaiacol is favored over that of aromatic C-OH on the created site.
研究领域:
催化化学
·
生物质能
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2021
·
IF 4.126
Weiyu Wang,Qiang Wang,Yueying Chu,Guodong Qi,Shenhui Li,Jun Xu,Feng Deng
Alkyne semihydrogenation offers a key approach for the synthesis of stereodefined molecules. The stereoselective hydrogenation of propyne to propene over Al2O3-supported Pd–Ag bimetallic catalysts is studied by using parahydrogen-induced polarization (PHIP) NMR technique. The supported catalysts were prepared by an incipient-wetness impregnation method, and their properties were systemically tuned by altering Pd and Ag components. Structural characterization by X-ray diffraction, infrared spectra, and transmission electron microscope shows the formation of highly dispersed bimetallic Pd–Ag nanoparticles with random alloy structures on Al2O3 support. For the hydrogenation of propyne over Pd–Ag catalysts with higher Ag concentration, the adsorbed protons are mostly restricted on the active Pd ensembles, which favors a higher pairwise hydrogen addition to propyne, leading to a stronger PHIP effect. The product stereoselectivity measurements show that the pairwise syn-addition to propyne increases with Ag content in the Pd–Ag alloy. The reaction conditions impact the pairwise hydrogenation stereoselectivity. A lower H2/propyne ratio of reactant flow or a higher total reactant flow rate enhances the apparent pairwise syn-addition stereoselectivity, which can be accounted for by the suppressed cis–trans isomerization process and/or a higher intrinsic pairwise syn-addition selectivity.
研究领域:
催化化学
·
物理化学
·
材料科学
✓ 已验证
DOI
高影响因子
Chem Catalysis
·
2024
·
IF 11.5
Ji Wei Sun,Tingting Yu,Haoran Wu,Minghui Zhu,Aiping Chen,Cheng Lian,Hua Gui Yang,Peng Fei Liu
High cost of pure CO 2 feed constitutes a significant economic obstacle in industrial-scale CO 2 electrolysis. Direct CO 2 electrochemical conversion from flue gas has emerged as a promising strategy to reduce feed cost, while the O 2 in flue gas cannot be ignored due to its strong reactivity. Here, we achieved fast, selective CO electrosynthesis directly fed with simulated oxygen-containing flue gas (95% CO 2 +5% O 2 ) over the amine-confined Ag catalysts in a flow cell, among which dimethylamine-modified Ag exhibited 80.6% CO Faradaic efficiency with partial current density of 333.7 mA cm −2 . In situ spectroscopy demonstrated that dimethylamine confinement endows a robust CO 2 adsorption-conversion capacity. Theoretical calculations further elucidated that amine modification could not only mediate CO 2 adsorption and ∗COOH intermediate formation but could also block the ∗OOH intermediate pathway in the side reaction of oxygen reduction. These findings pave a new avenue for rational design of amine-confined electrocatalysts for direct flue gas conversion and utilization.
研究领域:
化学工程
·
环境科学
·
电催化
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2022
·
IF 4.889
Lanqing Deng,Lang Chen,Liangdi Zhu,Yang Li,Jie Ou-Yang,Shaofeng Wu,Peng Chen,Sheng Shen,Junkang Guo,Yongbo Zhou,Chak-Tong Au,Shuang-Feng Yin
Being extensively applied in various fields of chemistry and chemical industry, the development of a green and versatile method for the synthesis of amides is in line with the demand of sustainable chemistry. Herein, a direct, highly selective, and scale-up (5–20 mmol) method for photocatalytic synthesis of amides through aerobic oxidative amination of alcohols with amines was developed under visible light, room temperature, using air as the oxidant. Benefiting from the adsorption of sodium hemiaminal on catalyst lengthens the C H bond (1.148 Å), this novel process is feasible for a broad range of functionlized amides (69 examples), especially those for drug manufacture (e.g., moclobemide and pipobroman). Imines was almost prevented with excellent amide selectivity up to 99 % could be ascribed to the low energy barrier for hemiaminal dehydrogenation while that for dehydration is high (2.13 eV). This green and efficient protocol represents an ideal alternative to the currently known methods.
研究领域:
有机化学
·
催化化学
·
环境化学
✓ 已验证
产品关联
DOI
高影响因子
CURRENT ORGANIC SYNTHESIS
·
2017
·Vol. 14
·期 8
·1185-1192
·
IF 1.917
Zhou Zhi-Hua,Guo Chun-Xiang,Xie Jia-Ning,Liu Kai-Xuan,He Liang-Nian
Aim and Objective: The carboxylation of organoboronic esters with CO2 is an attractive way of preparing the functionalized carboxylic acid derivatives. For the silver-catalyzed carboxylation of arylboronic esters with CO2, sensibility of catalytic system to CO2 pressure resulted in
a high CO2 pressure required in the reaction. This work focuses on solving this problem and promoting this transformation under atmospheric CO2 pressure. Material and Method: Arylboronic esters were synthesized according to the published procedure. Arylorganic esters, silver compound,
base, PPh3 and solvent were introduced into a 25 mL Schlenk flask. Then, the gasexchanging operation via a “freeze-pump-thaw” method was conducted. After being enclosed with a CO2 balloon, the resulting mixture was stirred at 70oC for 12 h. Then, the reaction was quenched by 1
M HCl and extracted with ethyl acetate. The yields of the corresponding carboxylic acids were determined by GC. The structures of products were confirmed by NMR and GC-MS. Results: The carboxylation of arylboronic esters with ambient CO2 was achieved on the basis of the silver chloride/triphenylphosphine
system by using cesium carbonate as the base and dimethyl sulfoxide as the solvent. Through this protocol, various functionalized carboxylic acids were synthesized in 85-99% yields. Conclusion: The silver-catalyzed carboxylation of arylboronic esters with ambient CO2 was established.
This approach represents an alternative way to prepare carboxylic acids derivatives from the organoboron compounds with CO2 under mild reaction conditions.
研究领域:
有机化学
·
环境化学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2021
·
IF 19.503
Ke Ye,Tianfu Liu,Yanpeng Song,Qi Wang,Guoxiong Wang
Electrochemical CO 2 reduction reaction (CO 2 RR) offers an appealing route to simultaneously store intermittent renewable energy as value-added chemicals and close carbon cycle. Silver (Ag) catalyst is a promising candidate for the electrochemical conversion of CO 2 to CO, but the electrocatalytic properties are still insufficient for practical applications. Herein, we put forward a strategy to in situ reconstruct a heterogeneous Ag 2 S/Ag interface structure, in which their strong interactions facilitate CO 2 RR performance. The in situ reconstructive Ag 2 S/Ag catalyst achieves a large current density of 421.7 ± 14.4 mA cm –2 at –0.70 V vs . reversible hydrogen electrode (RHE) and maintains steadily at a current density of 244.5 ± 31.8 mA cm –2 and CO Faradaic efficiency of 99.1 ± 0.8 % at –0.49 V vs . RHE for 50 h, superior to state-of-the-art CO-selective Ag-based catalysts. Density functional theory calculations reveal that the in situ reconstructive Ag 2 S/Ag interface active sites stabilize the *COOH intermediate during CO 2 RR process.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED POWDER TECHNOLOGY
·
2022
·
IF 4.969
Like Sun,Haoyang Huang,Ping Che,Qiang Lin,Kuo Lian,Jinbing Li,Yu Zhang,Yongsheng Han
Silver particles supported on alumina are the main industrial catalysts for ethylene epoxidation. Silver catalysts are usually produced by an impregnation method followed by thermal decomposition. Although the decomposition process determines the structures and properties of silver catalysts, we are short of information on this high temperature process. Herein we employed a confocal laser scanning microscope (CLSM) equipped with a heating stage to disclose the thermal decomposition process of silver precursor towards the preparation of high selective silver catalysts. It is found that the formation of silver catalysts experiences two steps: crystallization and decomposition. The crystallization occurs at the temperature below 80℃, resulting in the formation of silver complex. Further heating the sample to 140℃, leads to the formation of silver particles at alumina wafers. The atmosphere has a significant effect on the formation and performance of catalysts. When the samples are heated in the nitrogen, small silver particles with similar size are formed, which leads to a high selectivity of ethylene epoxidation. The role of thermal atmospheres on the size and property of silver catalysts is discussed in this paper.
研究领域:
化学工程
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Chemistry
·
2024
·
IF 14
Haotian Duan,Wenyang Li,Lixiu Ran,Fulong Zhu,Tianxiang Li,Ming Miao,Wen-jin Yin,Xin Wang,Yongzhu Fu
The conversion of carbon dioxide to ethylene by electrochemical reduction (CO 2 RR) provides a new strategy for achieving carbon dioxide conversion. However, copper-based catalysts have the disadvantages of unsatisfactory selectivity and low current density, which limit the potential CO 2 RR industrial expansion. Researches have verified that the real reaction sites at the catalyst surface often undergo reconstruction during the reaction, therefore, understanding and utilizing this phenomenon is crucial for improving catalytic performance. In this work, we introduced additional Ag component into Cu@Ag/C tandem catalyst by in-situ electrochemical reconstruction of Cu 2 CO 3 (OH) 2 /AgCl/C precursor. This electro-reduced catalyst exhibits a C 2 H 4 Faradaic efficiency of 50.41% in H-cell, and 58.03% in the flow cell, surpassing the counterparts of pure Cu and Ag, as well as the Cu-Ag homolog with separated interface. Moreover, it also provides a long-term stability of 21 h with the ethylene Faraday efficiency (FE) over 50%. The appropriate amount of Ag dopant into the Cu catalyst changes the electronic structure of Cu surface by the electron transfer from Cu to Ag, which distinctly enhances the binding energy of CO 2 on the catalyst. Meanwhile, in-situ Raman results and theoretical calculation reveal that the introduction of silver increases the number of active sites and improves the coverage of *CO intermediate, thereby accelerating the kinetics of C–C coupling and reducing its energy barrier. The combination of cascade catalytic strategy and in-situ electroreduction interface provides potential applications for future artificial carbon balance.
研究领域:
材料科学
·
电化学
·
催化反应
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2019
·
IF 4.309
Tao Liu,Cong Xi,Cunku Dong,Chuanqi Cheng,Jiayi Qin,Shanwei Hu,Hui Liu,Xi-Wen Du
Interfacial electron transfer (IET) at the metal–solution interface is known as a rate-determining step for many electrocatalytic reactions. Hitherto, there is still lack of physical insight into the IET process, as well as an experimental physical quantity directly linked to the IET rate. In this work, we propose that the work function can serve as an indicator for the IET rate of same metals such as silver quantum mechanical analysis demonstrates that a decrease in the work function can dramatically enhance the IET process. To experimentally verify this hypothesis, three different silver catalysts are prepared for CO2 electroreduction. The experimental results confirm that reducing work function of silver catalysts can improve the IET, according to the change of the Tafel slope. Resultantly, the silver catalyst with smaller work function achieves higher activity and selectivity for CO production. This study demonstrates a promising strategy to enhance the performance of same metal catalysts through tuning its work function.
研究领域:
物理化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2019
·
IF 7.723
Haiqiang Lin,Hongyan Qu,Weikun Chen,Kang Xu,Jianwei Zheng,Xinping Duan,Hesheng Zhai,Youzhu Yuan
In gas-phase chemoselective hydrogenation of crotonaldehyde on Ag-based catalysts, zirconia doping on silica supports was found to improve catalytic performance in terms of unsaturated alcohol selectivity, hydrogenation activity, and stability. The surface modification of silica by zirconia doping favors the fine dispersion of Ag species due to the enhanced quantity and strength of surface acid sites, which enable construction of abundant catalytic sites effective for C O bond hydrogenation. High crotyl alcohol selectivity, exceeding 80%, and significant inhibition of monohydrogenation on the C C bond were observed on the optimal Ag/Zr–SiO 2 catalyst. Dynamic O 2 chemisorption measurement revealed that the pure Ag powders did not chemisorb O 2 irreversibly under 323 K, but SiO 2 or Zr–SiO 2 supported Ag catalysts did. The amounts of Ag active for O 2 chemisorption, which are at least one order of magnitude lower than that of surface Ag derived from TEM and XRD characterizations, match well with the perimeter interface Ag of hemispherical particles. A strong correlation between hydrogenation activity and O 2 uptake on those Ag/SiO 2 and Ag/Zr–SiO 2 catalysts with different Ag dispersions and deactivation degrees was observed, implying that the effective catalytic sites for crotonaldehyde chemoselective hydrogenation may originate from accessible interface sites with unique redox properties. Catalyst induction and deactivation were observed on both Ag/SiO 2 and Ag/Zr–SiO 2 catalysts in real catalytic operation. Changes in metal stable interface structure, rather than metal aggregation and coagulation, are assumed to be the main cause of irreversible catalyst deactivation, because the apparent Ag particle sizes changed slightly, but the oxygen chemisorption ability deteriorated considerably. Electropositive Ag sites interacting with neighboring oxygen from oxide supports at the ternary Ag–ZrO 2 –SiO 2 interface are proposed to account for highly selective C O bond hydrogenation to produce the desired unsaturated alcohol.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 59
·54020-54026
·
IF 3.289
Jikuan Qiu,Yuling Zhao,Huiyong Wang,Guokai Cui,Jianji Wang
Development of new efficient catalytic systems for chemical transformation of CO2 is a very attractive topic in green chemistry. In this work, we studied the synthesis of α-alkylidene cyclic carbonates through the coupling reaction between propargylic alcohols and CO2 with new silver catalysts. It was found that activated carbon supported AgX (X = Br and I) was a simple and efficient catalyst for the carboxylative cyclization of propargyl alcohols with CO2 at atmospheric pressure and room temperature. Nearly 99% yield of the desired product was obtained, and the product could be simply separated through solvent extraction. Moreover, the catalyst could be easily recovered and reused at least ten times without a decrease in the catalytic activity and selectivity. These findings are useful for the development of an environmentally friendly chemical process for the production of α-alkylidene cyclic carbonates.
研究领域:
绿色化学
·
催化化学
✓ 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）