Catalysts
·
2018
·Vol. 8
·期 1
·37
·
IF 3.465
Yang Zheng,Yangyang Guo,Lei Luo,Tingyu Zhu
The performance of activated carbon (AC) modified by different methods was compared for its catalytic degradation of ortho-chlorophenol (o-CP). For the chemically treated AC, the catalytic effect of AC–NH3·H2O was superior to the other catalysts examined, having ano-CP removal efficiency of 82.2% at 330 °C. For the metal-modified catalysts, AC–V and AC–Co showed similar removal performances of 93.2% at 330 °C. N2adsorption-desorption isotherms, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and gas chromatography—mass spectrometry (GC-MS) analyses were used to characterize the reaction products, and different reaction mechanisms were proposed for both AC–NH3·H2O and AC–V according to the results. Complete oxidative degradation ofo-CP was achieved by AC–V, with AC–NH3·H2O leading to the formation of additional dioxins. It can be deduced that a risk of dioxin synthesis and escape during the regeneration process is possible when nitrogen-modified carbon is used in selective catalytic reduction (SCR) denitrification reactions, especially in the presence of chlorine atoms, benzene rings, and oxygen.Keywords:catalysis;modified carbon;ortho-chlorophenol;degradation mechanism
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2023
·
IF 7.2
Samuel Guemou,Fuying Wu,Pengzhou Chen,Jiaguang Zheng,Ting Bian,Danhong Shang,Alexei Pavlovich Levtsev,Liuting Zhang
Transition metal-based oxides have been proven to have a substantial catalytic influence on boosting the hydrogen sorption performance of MgH 2 . Herein, the catalytic action of Ni 6 MnO 8 @rGO nanocomposite in accelerating the hydrogen sorption properties of MgH 2 was investigated. The MgH 2 + 5 wt% Ni 6 MnO 8 @rGO composites began delivering H 2 at 218 °C, with about 2.7 wt%, 5.4 wt%, and 6.6 wt% H 2 released within 10 min at 265 °C, 275 °C, and 300 °C, respectively. For isothermal hydrogenation at 75 °C and 100 °C, the dehydrogenated MgH 2 + 5 wt% Ni 6 MnO 8 @rGO sample could absorb 1.0 wt% and 3.3 wt% H 2 in 30 min, respectively. Moreover, as compared to addition-free MgH 2 , the de/rehydrogenation activation energies for doped MgH 2 composites were lowered to 115 ± 11 kJ/mol and 38 ± 7 kJ/mol, and remarkable cyclic stability was reported after 20 cycles. Microstructure analysis revealed that the in-situ formed Mg 2 Ni/Mg 2 NiH 4 , Mn, MnO 2 , and reduced graphene oxide synergically enhanced the hydrogen de/absorption properties of the Mg/MgH 2 system.
研究领域:
材料科学
·
能源化学
✓ 已验证
DOI
高影响因子
FUEL
·
2020
·
IF 5.578
Ruonan Zheng,Dong Liu,Junshi Tang,Qiang Song,Qiang Yao
Coke formation during the process of in-situ combustion is affected by clay minerals, among which montmorillonite shows the most significant effect. A fixed-bed reactor was used to conduct the thermal conversion experiments of heavy oil and model compounds to reveal the mechanism of montmorillonite affecting the coke formation. Under the inert atmosphere, in the presence of montmorillonite, the temperature at which aromatic C–C groups of coke appeared decreased from 500 °C to 450 °C and polymers were formed when toluene was heated, indicating that montmorillonite catalyzed aromatization and polymerization, respectively. The increase in the supporter surface area promoted the formation of coke from pyrolysis by shortening the induction of coking. Under the oxidizing atmosphere, in the presence of montmorillonite, the initial temperature of O 2 consumed by heavy oil decreased from 270 °C to 250 °C, indicating that montmorillonite catalyzed oxygen-adding reaction. The temperature of CO x released by acetaldehyde and acetic acid decreased, and the release amounts increased, indicating that montmorillonite catalyzed decarbonylation and decarboxylation. Polymers were formed when acetaldehyde, acetic acid, ethanol, and acetone were heated, indicating that montmorillonite catalyzed polycondensation. When the oil mass fraction in the sample was within 18%, further increase in the supporter surface area did not affect the formation of coke from oxidation. The catalysis of montmorillonite was the main mechanism affecting coke formation during the thermal conversion of heavy oil under the inert and oxidizing atmospheres.
研究领域:
石油工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2021
·
IF 9.229
Haizhen Liu,Chenglin Lu,Xinchun Wang,Li Xu,Xiantun Huang,Xinhua Wang,Hua Ning,Zhiqiang Lan,Jin Guo
Two-dimensional vanadium carbide (V2C) and titanium carbide (Ti3C2) MXenes were first synthesized by exfoliating V2AlC or Ti3AlC2 and then introduced jointly into magnesium hydride (MgH2) to tailor the hydrogen desorption/absorption performances of MgH2. The as-prepared MgH2–V2C–Ti3C2 composites show much better hydrogen storage performances than pure MgH2. MgH2 with addition of 10 wt % of 2V2C/Ti3C2 initiates hydrogen desorption at around 180 °C; 5.1 wt % of hydrogen was desorbed within 60 min at 225 °C, while 5.8 wt % was desorbed within 2 min at 300 °C. Under 6 MPa H2, the dehydrided MgH2–2V2C/Ti3C2 can start to recover hydrogen at room temperature, and 5.1 wt % of H2 is obtained within 20 s at a constant temperature of 40 °C. The reversible capacity (6.3 wt %) does not decline for up to 10 cycles, which shows excellent cycling stability. The addition of 2V2C/Ti3C2 can remarkably lower the activation energy for the hydrogen desorption reaction of MgH2 by 37% and slightly reduce the hydrogen desorption reaction enthalpy by 2 kJ mol–1 H2. It was demonstrated that the combination of V2C and Ti3C2 promotes the hydrogen-releasing process of MgH2 compared with addition of only V2C or Ti3C2, while Ti3C2 impacts MgH2 more significantly than V2C in the hydrogen absorption process of MgH2 at ambient temperatures. A possible mechanism in the hydrogen release and uptake of the MgH2–V2C–Ti3C2 system was proposed as follows: hydrogen atoms or molecules may preferentially transfer through the MgH2/V2C/Ti3C2 triple-grain boundaries during the desorption process and through the Mg/Ti3C2 interfaces during the absorption process. Microstructure studies indicated that V2C and Ti3C2 mainly act as efficient catalysts for MgH2. This work provides an insight into the hydrogen storage behaviors and mechanisms of MgH2 boosted by a combination of two MXenes.
研究领域:
材料科学
·
能源存储
✓ 已验证
DOI
PubMed
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2025
·
IF 2.5
Jian-Wu Xiao,Li-Wang Jiang,Yu-Ma Yang,Yun-Feng Zhu,Fu-An He,Dong-Dong Mai
Superhydrophobic electrospun films for oil–water separation, particularly those with multiple functions such as magnetism, catalysis, and piezoelectricity, have received widespread attention. In this work, a novel electrospun superhydrophobic magnetic CoFe2O4@TiO2/polyvinylidene fluoride (PVDF) composite film was fabricated. Firstly, a CoFe2O4@TiO2 hybrid filler was prepared by a simple and effective solvothermal method, and its structure and magnetism were confirmed by different characterization techniques. Secondly, the electrospun CoFe2O4@TiO2/PVDF composite film was prepared and then modified with trimethoxy(1H,1H,2H,2H-heptadecafluorodecyl)silane (HFDS) to form the electrospun HFDS-CoFe2O4@TiO2/PVDF composite film. The resulting HFDS(2 wt%)-CoFe2O4@TiO2(30 wt%)/PVDF composite film was found to be superhydrophobic and could achieve oil–water separation by gravity filtration and direct absorption, with absorption capacities for valorous oils ranging from 7.7 g g−1 to 8.2 g g−1. The crystallinity degree of the polar piezoelectric β- and γ-form crystals of PVDF in the HFDS(2 wt%)-CoFe2O4@TiO2(30 wt%)/PVDF composite film was 25.1%, whereas the corresponding value of the pure PVDF solid film was only 14.3%. In addition, the HFDS(2 wt%)-CoFe2O4@TiO2(30 wt%)/PVDF composite film exhibited a magnetization strength of 0.69 emu g−1 at 20 000 Oe and could catalyze the degradation of Sudan Red dye. The multi-functional CoFe2O4@TiO2/PVDF composite film demonstrates its potential for various applications in oil–water separation and other fields.
研究领域:
材料科学
·
环境工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Ximei Liang,Fangling Guan,Zhiyou Ling,Honghong Wang,Yunwen Tao,Elfi Kraka,Huajun Huang,Chenglong Yu,Danping Li,Jinbao He,Hansun Fang
Photodegradation of the insecticide pymetrozine (PYM) was studied on surface of wax films, and in aqueous and nonaqueous phase. The half-life of PYM on the wax surface was approximately 250 times longer than in water. Scavenging experiments, laser flash photolysis, and spectra analysis indicated the first singlet excited state of PYM (S1 * PYM ) to be the most important photoinduced species initiating the photodegradation. Quantum chemistry calculations identified significant molecular torsion and changes in the structure C–C N–N of S1 * PYM , and the absolute charges of the C N atoms increased and the bond strength weakened. Free energy surface analysis, and O 18 labeling experiments further confirmed that the mechanism was two-step photoinduced hydrolysis. The first step is the hydrolysis of S1 * PYM at C N upon reaction with 2–3 water molecules (one H 2 O molecule as the catalyst). The second step is an intramolecular hydrogen transfer coupled with the cleavage of C–N bond and formation of two cyclic products. During the interactions, water molecules experience catalytic activation by transferring protons, while there is a negligible solvent effect. Clarifying the detailed photodegradation mechanisms of PYM is beneficial for the development of green pesticides that are photostable and effective on leaf surfaces, and photolabile and detoxified in the aquatic environment.
研究领域:
环境科学
·
农药化学
·
量子化学
✓ 已验证
DOI
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2023
·
IF 4.6
Darvaish Khan,Jianxin Zou,Saz Muhammad,Niaz Ali Khan,Shah Saud,Subrata Panda
In this study, a MgH 2 –Ru composite is prepared by mechanical ball milling of MgH 2 and Ru powders. The microstructural analysis revealed the uniform distribution of Ru nanoparticles in the MgH 2 matrix and the formation of intermetallic compounds (i.e. Mg 6.2 Ru and Mg 1.5 Ru) after dehydrogenation of the composite. The substantial improvements in the de/hydrogenation properties of MgH 2 are due to the adjustable catalytic role of Ru under low temperature and pressure conditions. MgH 2 –Ru composite started to release hydrogen at an onset temperature of 300 °C, much lower than the mechanically milled pure MgH 2 (350 °C). Hydrogen absorption of the MgH 2 –Ru composite is relatively fast at 350 °C and stored 6.1 wt% in 5 min. At the same temperature, the hydrogenated MgH 2 –Ru composite released all stored hydrogen in less than 5 min. Compared with the catalyst-free MgH 2 , the hydrogenation and dehydrogenation activation energies of the MgH 2 –Ru composite are reduced to 65.12 ± 2.4 kJ/mol H 2 , and 97.46 ± 4.15 kJ/mol H 2 , respectively. In addition, it further demonstrated how the reversible transformation of Mg–Ru intermetallic phases induces the thermodynamic destabilization of the MgH 2 system. The presence of Ru not only facilitated the breaking of the Mg–H bond but also provided very good catalytic interfaces for enhanced de/hydrogenation properties of MgH 2 .
研究领域:
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
THERMOCHIMICA ACTA
·
2023
·
IF 3.5
Lijuan Yan,Baozhong Zhu,Xiaohan Yan,Wenhua Wang,Jiuyu Chen,Jun Liu,Yunlan Sun
Boron (B) is an ideal fuel due to its high mass and volumetric calorific values. However, its high ignition temperature and poor combustion efficiency affect its wide use in propellants. Nickel oxide (NiO) has been found to possess strong catalytic activity as a metal oxide in a transition state. In this study, composites of three different particle sizes of B particles and various concentrations of NiO were prepared. Thermal analysis, combustion process, and combustion mechanisms were investigated. Modifying B with NiO can decrease the initial oxidation temperature and ignition temperature. The flame temperature and combustion efficiency are increased after B powder is modified by NiO. The mechanism of the combustion reaction was further investigated to gain a deeper understanding of the NiO-catalyzed B oxidation process.
研究领域:
材料科学
·
燃烧学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
WATER RESEARCH
·
2024
·
IF 11.4
Xuecong Qian,Shilong Wang,Haijun Cheng,Luwei Li,Yun Liu,Jinhao Duan,Da Wang,Jun Ma
Fe(II) and Mn(II) are abundant in groundwater and require operationally simple and efficient method to remove in drinking water treatment. The rapid oxidation of Mn(II) is essential in water treatment. This study investigates the efficiency of Mn(II) oxidation by free chlorine in the presence of Fe(II). The results demonstrate that the presence of Fe(II) significantly accelerates the oxidation rate of Mn(II) by free chlorine under neutral and alkaline conditions. The rapid oxidation of Fe(II) by free chlorine and the presence of Mn(II) promote the formation of in situ Mn(II)-doped ferrihydrite. Kinetic modeling and characterization of Fe(III) oxides confirm that the heterogeneous catalytic effect of the Mn(II)-doped ferrihydrite, rather than manganese oxides or their coupled catalytic effect, is responsible for the enhanced oxidation rates. The doped Mn(II) substitutes the tetrahedral Fe(III) ions in the ferrihydrite, introducing additional negative charges at the doped sites. The increased charge enhances Mn(II) adsorption and lowers its redox potential, thereby accelerating Mn(II) oxidation rate through direct electron transfer with adjacent free chlorine. Additionally, the lepidocrocite formed by the reaction between Fe(II) and dissolved oxygen significantly impedes the catalytic performance. These findings provide new insights into the catalytic co-oxidation mechanism of Fe(II) and Mn(II), and help the optimization of water treatment engineering practices.
研究领域:
环境科学
·
水处理工程
·
化学动力学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2022
·
IF 4.331
Shizhong Zhang,Chuanbiao Zhang,Yang Fu,Linhai Li,Chuanbing Huang,Yang Lin,Chongqin Zhu,Joseph S. Francisco,Zhiyuan He,Xin Zhou,Jianjun Wang
Ice affects many chemical reactions in nature, which greatly influences the atmosphere, climate, and life. However, the exact mechanism of ice in these chemical reactions remains elusive. For example, it is still an open question as to whether ice can act as a catalyst to greatly enhance the reactivity and selectivity, which is essential for the production of some natural compounds in our planet. Here, we discover that ice can lead to high efficiency and stereoselectivity of the [2 + 2] photodimerization of coumarin and its derivatives. The conversion of the [2 + 2] photodimerization of coumarins enhanced by ice is dozens of times higher than that in the unfrozen saturated solution, and the reaction displays a high syn-head-head stereoselectivity (>95%) in comparison with those in the absence of the ice. Note that almost no reaction occurs in the crystal powder and melt of the coumarins, indicating that the role of ice in the photodimerization reaction is not simply due to the usual mechanisms found in the freezing concentration. We further reveal that the reaction rate is found to be proportional to the total area of the ice surface and follows Michaelis–Menten-like kinetics, indicating that the ice surface catalyzes the reaction. Molecular dynamics simulations demonstrate that ice surfaces can induce reactants to form a two-dimensional liquid-crystal-ordered layer with a suitable intermolecular distance and unique side-by-side packing, facilitating stereoselective photodimerization for syn-head-head dimers. These findings give evidence that ice-surface-induced molecular assembly may play an important role in atmospheric heterogeneous photoreaction processes.
研究领域:
化学
·
环境科学
✓ 已验证
DOI
PubMed
高影响因子
Catalysts
·
2023
·Vol. 13
·期 5
·915
·
IF 3.9
Xiaofeng Yu,Chunjie Shi,Yueling Cheng,Yejing Zhu,Renyuan Song,Shengfei Hu
Methyl benzoate (MB) compounds are prepared by reacting various benzoic acids with methanol using an acidic catalyst. In this study, the solid acids of zirconium metal solids fixed with various substances were studied. We determined that zirconium metal catalysts with fixed Ti had the best activity. The catalytic synthesis of a series of MB compounds using titanium zirconium solid acids was studied. The direct condensation of benzoic acid and methanol using a metallic Lewis acid without other auxiliary Bronsted acids is reported for the first time.Keywords:methyl benzoate;solid acid;catalysis
研究领域:
有机化学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF VINYL & ADDITIVE TECHNOLOGY
·
2022
·Vol. 28
·期 3
·604-614
·
IF 2.297
Zhihao Zhang,Zhongying Ma,Dan Zhang,Yuhua Wang
The intumescent flame retardant coating consisting of polyethylenimine (PEI) and poly sodium phosphate has various drawbacks including poor water durability, inferior flame retardancy, and large consumption of nonrenewable raw resources. An intumescent fire retardant coating coordinating with manganese ions was designed onto the cotton fabrics surface by a layer-by-layer assembly method to solve these concerns. Energy dispersive spectroscopy revealed that the coating included well-distributed manganese ions. The thermogravimetric measurement showed that after adding manganese ions into the coating, the decomposition of treated fabrics shifted towards a lower temperature and more char residues were formed due to the catalytic effect of manganese ions. Coated cotton fabrics with manganese ions yielded the most reduction in peak heat release rate and the highest rise in char residues, up to 69.1% and 34.7%, respectively, in microscale combustion calorimeter results. Limiting oxygen index (LOI) of the samples with manganese ions was the highest, up to 28.3% and the char layer was more intact and continuous after vertical combustion test. Scanning electron microscopy analyses showed that treated cotton fabrics with manganese ions had more bubbles and char residues on the fiber surface. These findings indicated that manganese ions coordination was responsible for the catalytic and synergistic effects. Furthermore, the coating containing manganese ions exhibited better water endurance owing to high-LOI values even after rinsing. This work shows manganese ions into intumescent flame retardant coatings improves cotton fabrics flame retardancy and water resistance.
研究领域:
材料科学
·
纺织工程
✓ 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）