Royal Society Open Science
·
2018
·Vol. 5
·期 6
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IF 2.504
Cheng Wang,Liya Hu,Meiyin Wang,Bin Yue,Heyong He
A series of Cex-V-g-C3N4 catalysts with different cerium content were synthesized by a facile co-assembly method. Compared with pure V-g-C3N4 catalyst, the addition of cerium facilitated the high dispersion of vanadium species as well as the benzene adsorption ability of the corresponding catalysts. Also, the existence of cerium promoted the partial reduction of vanadium species, which improved the redox property of vanadium species as the active centres. The Cex-V-g-C3N4 catalysts showed considerably improved activity in the benzene hydroxylation reaction compared with V-g-C3N4 catalyst. Among the catalysts studied, Ce0.07-0.07 V-g-C3N4 exhibited the best catalytic activity with a benzene conversion of 33.7% and a phenol yield of 32.3% with good structural and catalytic stability, while only 24.7% of benzene conversion and phenol yield of 24.2% were obtained over 0.07 V-g-C3N4.
研究领域:
化学工程
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催化材料科学
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DOI
PubMed
高影响因子
ChemistrySelect
·
2023
·Vol. 8
·期 29
·e202301223
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IF 2.1
Yingwei Li,Shengxin Chen,Ying Jin,Xinxin Li,Ruirui Zhang,Ruixia Liu
Graphical A simple and controllable defect construction method for vanadium-oxygen catalysts through hydrogen reduction with TCD detector were used to control the reduction state of CHR-VOx which determines the V-Species and O-Species. Furthermore, the structure-performance relationship and the catalytic pathway were assumed, multi-liganded-oxygen and V 4+ species are the key parameters. A series of controlled-hydrogen-reduction VO x (CHR-VO x ) were prepared after our controllable hydrogen treatment, and CHR-VO x were controlled to be reduced to the states dominated by V 5+ and V 4+ species, subsequently the catalytic roles of V-species and O-species for cyclohexane (CHA) oxidation were explored. As expected, the surface properties of CHR-VO x have occurred remarkable change resulting in a significantly improvement on catalytic performance determined by V-species and O-species. The reduction behavior of the properties was recognized by XPS and Raman. Generally, the moderate-reduced CHR-VO x which possessed most 78.7 % multi-liganded-oxygen ( L O) performed the best conversion for CHA (11.8 %), and the over-reduced CHR-VO x with a large content of V 4+ species (33 %) performed a best selectivity for adipic acid (44.3 %). In this case, L O sites were regarded as the active site to accelerate the activation of CHA, while V 4+ species were regarded as the oxygen vacancies (OVs) through V 4+ −OV to contribute to the further oxidation to adipic acid.
研究领域:
催化化学
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材料科学
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DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
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2022
·
IF 5.876
Zhibo Xu,Fumin Wang,Xubin Zhang,Yi Zhai,Linfang Jiang,Kaiwei Wang,Yongwang Li,Qing Zhang
To enhance the doping of vanadium in zeolites and achieve high stability, the selection of vanadium precursors containing specific vanadium species can effectively overcome this crucial problem. Two series of V x Si-Beta(A) and V x Si-Beta(N) zeolites have been prepared by a two-step post-synthesis method at pH = 1 and pH = 7. The properties and environments of vanadium in samples are investigated by UV–vis, XPS, EPR, H 2 -TPR and 51 V MAS NMR. The bonding between vanadium and framework in VSi-Beta(A) is stronger than that of VSi-Beta(N). After the two are calcined or hydrated, the vanadium species in the former are relatively stable, while the pseudo-tetrahedral V(V) species and pseudo-octahedral V(V) species in the latter are interconverted. The changes of vanadium species in the supernatant during the preparation have been investigated by 51 V static NMR. At low concentration and pH = 1, there is a unique mononuclear cation (VO 2 + ) in the aqueous NH 4 VO 3 solution, which is favorable for the interaction with the negatively charged hydroxyl nests generated after the nitric acid dealumination , and enables the V atoms to be tightly inserted into the framework. In styrene epoxidation, the type of V(V) species in the catalyst could significantly affect its catalytic performance, and the catalytic activity and stability of V x Si-Beta(A) are superior than that of V x Si-Beta(N).
研究领域:
材料科学
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催化化学
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DOI
高影响因子
TALANTA
·
2023
·
IF 6.1
Xiaochong Song,Mingming Peng,Qing Luo,Xiaojia Huang
The dominant species of vanadium (V) are V(IV) and V(V) which exhibit different toxicity and biological effects. Thus, speciation of V(IV) and V(V) is highly essential. Efficient sample preparation is the core step in the quantification of V(IV) and V(V). In the present study, a new task specific microextraction column based on monolith mingled with Fe 3 O 4 nanoparticles (MBMC) was in situ synthesized in capillary and utilized as the extraction phase of magnetic field-assisted in-tube solid phase microextraction (MA-IT-SPME) of V(IV) and V(V) species which were coordinated with ethylene diamine tetraacetic acid (EDTA). The prepared MBMC presented porous and superparamagnetic properties, and possessed abundant functional groups. Results revealed that the exertion of magnetic field during adsorption and eluting steps boosted the extraction efficiency of V(IV)-EDTA and V(V)-EDTA chelates from 65.1 % to 55.7 %–90.0 % and 80.1 %, respectively. Under the beneficial extraction parameters, the established MA-IT-SPME was online hyphenated with HPLC/DAD to perform speciation of trace vanadium in water and vegetable samples, the achieved limits of detection were 0.054–0.060 μg/L and 1.4–1.5 μg/kg in water and vegetable samples, respectively, and the spiked recoveries varied from 82.5 to 118 %. In addition, relevant extraction mechanism under magnetic field was explored. In comparison with existing methods, the developed MA-IT-SPME technique displays some attractive merits such as automation, good anti-interference ability, high extraction efficiency, low cost and less use of organic solvent, in the capture of V species. The established online MBMC@MA-IT-SPME-HPLC/DAD system can become a competitive approach for sensitive speciation of V(IV) and V(V) at trace levels in complex samples.
研究领域:
分析化学
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环境科学
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DOI
PubMed
高影响因子
ANALYTICAL CHEMISTRY
·
2022
·
IF 8.008
Liang Dong,Hanjiao Chen,Yongyan Ning,Yaowen He,Ying Yu,Ying Gao
Photochemical vapor generation (PVG) is emerging as an alternative sample introduction method in the field of atomic spectrometry. The addition of transition metals can largely improve the PVG yields of elements with the enhancement of 1.4 to 30 000-fold, based on previous reports. In this work, the use of vanadium species as novel “sensitizers” in PVG was first reported, tellurium (Te) was selected as the target. The efficient photochemical reduction of Te was observed in the presence of 9% (v/v) formic acid (FA), 20%(v/v) acetic acid (AA), and 40 mg L–1 of V(V) (existing as VO3–) with the conversion efficiency of 87 ± 3%. Under the selected conditions, there was no significant difference in analytical sensitivity between Te(IV) and Te(VI), making the direct detection of total Te possible. The limit of detection (LOD, 3σ) was 2.9 ng L–1 for Te with inductively coupled plasma mass spectrometry (ICP MS) measurement. Good precisions of 2.3% and 2.2% (relative standard deviations, RSD) for seven times replicate measurement of 0.5 μg L–1 Te(IV) and Te(VI) standard solutions were obtained. The sensitivity was enhanced about 55-fold compared to that using traditional direct solution nebulization. The method was applied for the determination of trace Te in three water samples and two certified reference materials of sediment with satisfactory results. The possible mechanism was investigated. The generation of volatile vanadium along with (CH3)2Te was found in PVG for the first time. The new findings in this work will be helpful for exploration of efficient “sensitizers” in PVG and further expanding the scope of elements amenable to PVG as well.
研究领域:
分析化学
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环境科学
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DOI
高影响因子
Tungsten
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2025
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IF 11.2
Qian Qi-Ling,Zeng Zhen-Yun,Chen Wan-Ting,Cheng Yu,Zhang Jia,Li Chuan-Hua,Qian Guang-Ren
The promoter is very important for effective catalysts, and the relationship among active species, promoter, and support is a hot topic in the field of catalysis. This work aims to investigate the influence of the promoter on the formation of effective active species. For this purpose, V was leached out from V-loaded TiO 2 (V/Ti) step by step, and the loaded V was classified into different species based on their performances in the catalytic oxidation of chlorobenzene. As a result, when V/Ti was co-doped with Mo or W, the chlorobenzene conversion rate was increased from 48.1% to 54.0% (Mo) or 61.0% (W) at 210 °C. The enhancement was attributed to the redistribution of V species. Specifically, 7.8% of V was “Inactive” V on V/Ti. This “Inactive” V was transformed into an “Active” species. At the same time, “Highly-active V” amounts were increased from 86.0% (V 3.3 /Ti) to 88.1% (WV 3.3 /Ti) and 87.1% (MoV 3.3 /Ti). According to the mechanism investigation, when W and Mo coexisted with V during the synthesis, V 3+ was oxidized into V 5+ , which is easily invaded into the TiO 2 , created more strong acidic sites, and activated more active lattice oxygens. These are all in favor of the effective catalytic oxidation of chlorobenzene. The new understanding of the promoter effect will help to produce a more effective catalyst using the same amount of active species. Graphical abstract
研究领域:
催化化学
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材料科学
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环境化学
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物理化学
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DOI
高影响因子
BIOMASS & BIOENERGY
·
2024
·
IF 5.8
Zonghui Liu,Jing Xu,Zhe Wen,Bing Yan,Bing Xue
Designing and synthesizing bio-based catalysts for the catalytic conversion of biomass to high-value chemicals is a green and promising route in the field of sustainable chemistry. Herein, V x O y /NC_ P catalyst was synthesized by a simple impregnation-pyrolysis method using green and cheap bio-chitin or chitosan as the N-doped carbon (NC) precursor and was applied to the aerobic oxidation of ethyl lactate (EL) to ethyl pyruvate (EP). These catalysts were characterized by XRD, N 2 adsorption-desorption, SEM, TEM, XPS, and H 2 -TPR. When chitin was used as the NC precursor (V x O y /NC_chitin), the catalyst activity was significantly higher than that of chitosan as the NC precursor (V x O y /NC_chitosan). Correlation between catalytic performance and characterization results showed that the high surface area, abundant pyridinic-N, and low valence vanadium species (V 3+ and V 4+ ) played an important role in catalyst activity. A 97.3 % EL conversion with 97.8 % EP selectivity was obtained over V x O y /NC_chitin at 120 °C for 2 h, and no significant deactivation after five cycles. Moreover, this catalyst also showed a high activity in the selective oxidation of other alcohols to their corresponding aldehydes.
研究领域:
催化化学
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可持续化学
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材料科学
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DOI
高影响因子
Journal of Biobased Materials and Bioenergy
·
2018
·Vol. 12
·期 4
·321-329
·
IF 2.993
Liao Longfei,Liu Ying,Wu Shubin
A series of V2O5/SBA-15 catalysts with various loadings of 5, 10, 15 and 20% (by weight) V2O5 have been prepared by molecular designed dispersion (MDD) method and are characterized by N2 adsorption–desorption, Fourier Transform-Raman
spectroscopy (FT-Raman), transmission electron microscopy (TEM), low angle and wide-angle XRD, H2 temperature programmed reduction (TPR), inductively coupled plasma-optical emission spectrometry (ICP-OES), and Ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis, DRS) techniques.
Among V2O5/SBA-15 catalysts, the 10% V2O5/SBA-15 catalyst exhibited 88.6% 5-hydroxymethylfurfural (HMF) conversion with 57.9% yield of 2,5-diformylfuran (DFF) when molecular oxygen (0.28 MPa) and toluene were employed as green oxidant and organic
solvent respectively at 110 °C. The remarkable performance of 10% V2O5/SBA-15 catalyst is owing to the isolated distribution of uniform sized nanovanadium species which are dispersed on the pore surfaces of the hexagonally well-ordered mesoporous material SBA-15 silica
support.
研究领域:
催化化学
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绿色化学
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材料科学
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DOI
高影响因子
危险品化学品经营许可证（带存储）