Catalysts
·
2025
·Vol. 15
·期 4
·382
·
IF 4
Nan Lu,Yifeng Shi,Yutao Ren,Yue Wang,Xinyi Sun,Zejing Wei,Xutao Chen,Jie Fan
The oxidative coupling of methyl chloride (CH3Cl) to vinyl chloride (C2H3Cl) (MCTV) represents a promising yet challenging direct conversion route for C2H3Cl production. In this study, a novel catalyst, cristobalite silica, supported Na2WO4nanoclusters, was fabricated by calcining an intermediate composite composed by β-zeolite and sodium tungstate (Na2WO4). The pore structure of this β-zeolite possesses a regular shape and suitable size distribution, providing an accurate geometric matching effect for Na2WO4to homogeneously distribute in the entire β-zeolite matrix with high loading. Accordingly, the excellent dispersity of Na2WO4nanocluster active sites is well maintained even after calcining at 750 °C, and the microporous β-zeolite matrix is completely converted to dense cristobalite phase silica after the calcination. The high-loading and well-dispersed Na2WO4nanocluster leads to a superior performance in MCTV with a CH3Cl conversion of 81.5%, a C2H3Cl selectivity of 42.4%, and a C2H3Cl yield of 34.6%. Notably, the catalyst exhibits remarkable stability during the catalytic process.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2018
·Vol. 135
·期 25
·46375
·
IF 1.901
Zhixin Xiao,Yun Tan,Jianjun Ma,Di Wang,Lina Yu,Fan Yue,Shimei Xu,Jianbin Huang
A facile method was explored to synthesize thermosensitive poly[ N -isopropylacrylamide (NIPAM)- co -methacryloxyethyltrimethyl ammonium chloride (DMC)]/Na 2 WO 4 cationic hydrogels via copolymerization of NIPAM and DMC in the presence of Na 2 WO 4 . Na 2 WO 4 acted as both a physical crosslinking agent and a porogen precursor. The hydrogels were characterized by Fourier transform infrared spectroscopy, energy dispersive X-ray, thermogravimetry, environmental scanning electron microscopy, and transmission electron microscopy. Effects of various salt solutions, pH solutions on swelling were investigated. Thermosensitivity of the hydrogels were also investigated in various polar solvents at different temperatures. The resultant hydrogel showed a fast swelling rate and good salt tolerance. The hydrogels reached the swelling equilibrium within 10 min. Moreover, the swelling ratio of the hydrogels increased with the increase of the polarity of the solvent. In the water, the swelling ratio decreased with the increasing of temperature, but remained at a high level even at 80 °C since the pore structure weaken the lower critical solution temperature effect of PNIPAM. The swelling ratio increased instead in low polar solvent, while it became negligible in nonpolar solvent with the increasing of temperature. The whole swelling kinetics was fit for Schott's pseudo-second order model. The hydrogels have a great potential as catalysts and smart materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 46375.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Science Advances
·
2017
·Vol. 3
·期 6
·
IF 0
Pengwei Wang,Guofeng Zhao,Yu Wang,Yong Lu
Oxidative coupling of methane (OCM) is a promising method for the direct conversion of methane to ethene and ethane (C2 products). Among the catalysts reported previously, Mn2O3-Na2WO4/SiO2 showed the highest conversion and selectivity, but only at 800° to 900°C, which represents a substantial challenge for commercialization. We report a TiO2-doped Mn2O3-Na2WO4/SiO2 catalyst by using Ti-MWW zeolite as TiO2 dopant as well as SiO2 support, enabling OCM with 26% conversion and 76% C2-C3 selectivity at 720°C because of MnTiO3 formation. MnTiO3 triggers the low-temperature Mn2+↔Mn3+ cycle for O2 activation while working synergistically with Na2WO4 to selectively convert methane to C2-C3. We also prepared a practical Mn2O3-TiO2-Na2WO4/SiO2 catalyst in a ball mill. This catalyst can be transformed in situ into MnTiO3-Na2WO4/SiO2, yielding 22% conversion and 62% selectivity at 650°C. Our results will stimulate attempts to understand more fully the chemistry of MnTiO3-governed low-temperature activity, which might lead to commercial exploitation of a low-temperature OCM process.
研究领域:
化学工程
·
催化
·
能源化学
✓ 已验证
产品关联
DOI
PubMed
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2021
·
IF 19.503
Weidong Sun,Guofeng Zhao,Ya Gao,Jiaqi Si,Ye Liu,Yong Lu
Chemical looping concept paves way toward intrinsically safe and efficient oxidative coupling of methane (CL-OCM) process, because it permits the reaction to proceed via repeating reduction-oxidation cycle in two reactors. It is calling for a ground-breaking catalyst with enough high selective CH 4 -converting lattice-oxygen carrying capacity but represents a grand challenge. Herein, we report an efficient catalyst obtainable by decorating an oxygen carrier FeMnO 3 with Na 2 WO 4 , with good cycling performance, achieving a high space time yield of 29.8 g C2-C3 kg cat. −1 h −1 with 20% CH 4 conversion and 80% C 2 -C 3 selectivity at 800 °C and a low catalyst/CH 4 weight ratio of 13.5. CL-OCM process is established by “FeMnO 3 ↔ [MnFe 2 O 4 + MnO]” redox cycle. Na 2 WO 4 -decoration gets lattice oxygen stored in FeMnO 3 transformed from non-selective to selective due to mitigation of lattice-oxygen evolution. Scaled up CL-OCM testing with 10-gram catalyst also yields comparable results seen in the case of using 1-gram catalyst, validating great application potential.
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
Small
·
2023
·Vol. 20
·期 15
·2307998
·
IF 13.3
Jidong Duan,Fengqi Wang,Mengjie Huang,Maoxia Yang,Shaomin Li,Gen zhang,Chen Xu,Changyu Tang,Hao Liu
Single-crystal lithium-rich layered oxides (LLOs) with excellent mechanical properties can enhance their crystal structure stability. However, the conventional methods for preparing single-crystal LLOs, require large amounts of molten salt additives, involve complicated washing steps, and increase the difficulty of large-scale production. In this study, a sodium tungstate (Na 2 WO 4 )-assisted sintering method is proposed to fabricate high-performance single-crystal LLOs cathode materials without large amounts of additives and additional washing steps. During the sintering process, Na 2 WO 4 promotes particle growth and forms a protective coating on the surface of LLOs particles, effectively suppressing the side reactions at the cathode/electrolyte interface. Additionally, trace amounts of Na and W atoms are doped into the LLOs lattice via gradient doping. Experimental results and theoretical calculations indicate that Na and W doping stabilizes the crystal structure and enhances the Li + ions diffusion rate. The prepared single-crystal LLOs exhibit outstanding capacity retention of 82.7% (compared to 65.0%, after 200 cycles at 1 C) and a low voltage decay rate of 0.76 mV per cycle (compared to 1.80 mV per cycle). This strategy provides a novel pathway for designing the next-generation high-performance cathode materials for Lithium-ion batteries (LIBs).
研究领域:
材料科学
·
能源存储
✓ 已验证
DOI
高影响因子
ACS Omega
·
2024
·
IF 3.7
Qingjing Liu,Ruisheng Wang,Ranjia Li,Xiaosheng Wang,Suoqi Zhao,Changchun Yu
Mn–Na2WO4-based catalysts with different supports were prepared using the incipient wetness impregnation method and evaluated for their oxidative coupling of methane (OCM) reaction performance. The results demonstrated that the SiO2- supported catalyst exhibited the best catalytic performance, and the introduction of H2O further enhanced its activity. Under the conditions of a feed gas mixture of CH4/O2/H2O = 6:1:24 at 800 °C and atmospheric pressure, the CH4 conversion and C2+ selectivity over the Mn–Na2WO4/SiO2 catalyst increased from 28.4% and 77.4% (without H2O) to 33.2% and 84.9%, respectively. In contrast, the catalytic activity using TiO2 and MgO supports drastically declined. Characterizations using X-ray diffraction (XRD), in situ infrared spectroscopy (In-situ IR), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), and oxygen temperature-programmed desorption (O2-TPD) revealed that the introduction of steam not only served as a diluent to decrease the partial pressures of the reactants CH4 and O2, thereby reducing deep oxidation reactions in the gas phase, but also interacted with surface oxygen species (O22–) and silica to form adjacent surface-bonded disilanol free radicals Si–OIH. This interaction facilitated the dehydrogenation and coupling of two methane molecules on the catalyst surface, resulting in the generation of C2+ products, significantly enhancing the catalytic activity and selectivity of OCM.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2022
·
IF 8.129
Dewang Zeng,Chen Wang,Tong Liu,Wentao Ou,Rui Xiao
Chemical looping methane oxidative coupling is a promising method to directly convert methane to C 2 products but is limited by the trade-off between CH 4 conversion and C 2 selectivity. Here, we develop a series of TiO 2 doped Na 2 WO 4 /Mn 2 O 3 /SiO 2 for chemical looping methane oxidative coupling and investigate the underline mechanism for the enhanced performance. The results show that 5 wt% TiO 2 doped Na 2 WO 4 /Mn 2 O 3 /SiO 2 exhibited 31.2% CH 4 conversion, which is 1.68 times as large as that of Na 2 WO 4 /Mn 2 O 3 /SiO 2 , without significantly decreasing C 2 selectivity (~70.3%). Pulse experiments show that TiO 2 improves the bulk oxygen diffusion, providing more surface oxygen to convert methane, thus leading to enhanced CH 4 conversion. O 1 s spectra manifests that the active oxygen content on the surface was not significantly increased by TiO 2 dopant , thus TiO 2 dopant has little effect on C 2 selectivity. Therefore, 5 wt% TiO 2 doped Na 2 WO 4 /Mn 2 O 3 /SiO 2 shows high chemical looping methane oxidative coupling performance. The explored mechanism in this work can be extended to design more oxygen carriers to enhance the chemical looping reactions.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
SURFACE & COATINGS TECHNOLOGY
·
2026
·
IF 6.9
Jinjun Qiao,Lingyun An,Chenggong Chang,Haiyan Xia,Ziyi Wang,Leichao Meng,Zhanying Wang,Shenghua Ma,Jing Yuan
A corrosion-resistant plasma electrolytic oxidation (PEO) composite coating was fabricated on AZ31B magnesium alloy via incorporating a Na 2 WO 4 /SDS composite inhibitor, followed by silanization. The effects of the inhibitor on coating microstructure and corrosion resistance were investigated using XRD, FT-IR, XPS, SEM, potentiodynamic polarization and EIS. Silanization effectively sealed the PEO coating, increasing its thickness and compactness. Na 2 WO 4 and SDS further enhanced coating thickness and density, improving its physical barrier against corrosive media. The loaded Na 2 WO 4 reacted with dissolved Mg 2+ to form protective MgWO 4 , inhibiting substrate erosion. SDS's hydrophobic dodecyl chains adsorbed onto the coating, forming a directional hydrophobic layer that reduced water/Cl − contact and hindered corrosive media penetration. At the exposed substrate, SDS's hydrophilic end competed with adsorbed water via electrostatic attraction, suppressing hydrogen evolution and substrate corrosion. The P-W10S-SG coating (41.2 g/L Na 2 WO 4 , 10 g/L SDS) showed optimal performance. After 480 h immersion in 3.5 wt% NaCl, its |Z| 0.01Hz remained stable at 10 7 –10 8 Ω⋅cm 2 , representing five-order-of-magnitude improvement over pure PEO, and four orders over P-SG and P-W0S-SG coatings.
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2022
·
IF 10.383
Bo Xiao,Xin Li,Zijun Yi,Yubo Luo,Qinghui Jiang,Junyou Yang
Tin oxide (SnO2) has been commonly used as an electron transport layer (ETL) in planar perovskite solar cells (p-PSCs) because it can be prepared by a low-temperature solution-processed method. However, the device performance has been restricted due to the limited electrical performance of SnO2 and its mismatched energy level alignment with the perovskite absorber. Considering these problems, sodium tungstate (Na2WO4) has been employed to modify the SnO2 ETL. The conduction band minimum of SnO2 increases and the defects at the ETL/perovskite interface decrease by the modification of the SnO2 ETL with Na2WO4, thus reducing the energy barrier between the ETL and perovskite. In addition, the electron extraction ability has been enhanced and the interface recombination between the ETL and perovskite has also been inhibited. As a result, the photovoltaic performance of p-PSCs based on the modified ETL has been improved, and a champion power conversion efficiency of 21.16% has been achieved compared with the control device of 17.30% with an open circuit voltage increased from 1.075 to 1.162 V.
研究领域:
材料科学
·
能源技术
·
光电领域
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）