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Covalently tethering disulfonic acid moieties onto polyoxometalate boosts acid strength and catalytic performance for hydroxyalkylation/alkylation reaction

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Science China Chemistry 2022年第4期65卷 699-709页

作者： Lifei Lian Yubing Liu Xianfeng Yi Hanbin Hu Xiang Chen Hongqiang Li Wei Chen Anming Zheng Yu-Fei Song State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China Wuhan center for magnetic Resonance Key Laboratory of Magnetic Resonance in Biological SystemsState Key Laboratory of Magnetic Resonance and Atomic and Molecular PhysicsWuhan Institute of Physics and MathematicsChinese Academy of SciencesWuhan 430071China

Solid acid catalysts are widely used in the production of various high-value added and industrially important *** the use of organosilicon compounds to modify the vacancy site has been extensively studied,the covalent tethering-SO_(3)H functionalized organosilicon modified polyoxometalates(POMs)has been rarely *** this work,two catalysts(TBA_(4)[SiW_(11)O_(39)(O(SiC_(3)H_(6)SO_(3)H)_(2))](compound 2)and TBA_(4)[SiW_(11)O_(39)(O(SiC_(8)H_(8)SO_(3)H)_(2))](compound 3))were synthesized successfully through covalently grafting different sulfonic acid(-SO_(3)H)groups onto[SiW_(11)O_(39)]^(8−)cluster,*** 2 was achieved by surface grafting and in situ oxidation(3-mercaptopropyl)-trimethoxysilane,while compound 3 was achieved by surface grafting of 2-(4-chlorosulfonylphenyl)*** Brønsted acid strength of compounds 2 and 3 can be demonstrated by different methods including potentiometric titration,pyridine adsorption studies,and the ^(31)P trimethylphosphine oxides(TMPO)nuclear magnetic resonance(NMR).The systematic investigation of the relationship among POM structures,acid strength,and electron density was carried out based on density functional theory(DFT)calculation and experimental results,which revealed that covalent modification of compounds 2 and 3 decreased the electron density of the O-H bond,and promoted the release of H^(+).When applied in hydroxyalkylation/alkylation(HAA)reaction of 2-methylfuran(2-MF)with cyclohexanone,compound 2 exhibited better catalytic performance with conversion of ~93%,monocyclic fuel precursors(1a)yield of 79.9% and selectivity of 85.7% than compound 3,which can be attributed to strong Brønsted acid and the intramolecular hydrogen-bonding interactions between the neighboring -SO_(3)H moieties in compound ***,compound 2 also showed excellent catalytic activity in the HAA reaction of 2-MF with several different aldehydes and ketones(e.g.,furfuraldehyde,5-methylfurfurald

关键词： polyoxometalates sulfonic acid covalent modifications acid catalysis alkylation reaction

Deuterium Retention in SiC-Coated Graphite Tiles of EAST

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Plasma Science and Technology 2014年第3期16卷 193-196页

作者：赵利平王万景周海山吴婧谢春意李强杨钟时罗广南 Institute of Plasma Physics Chinese Academy of Sciences Research center of Laser fusion China Academy of Engineering Physics

Fuel retention and recycling in plasma facing materials is a crucial issue for fusion devices, especially for the long pulse discharge devices. In this work, the deuterium retention and the surface erosion of SiC-coated graphite tiles exposed to EAST plasmas have been studied by post-mortem analyses, i.e., thermal desorption spectroscopy （TDS）, secondary ion mass spec- troscopy （SIMS） and scanning electron microscopy （SEM）. The results show that the sample cut from the high field side （HF） tile has been intensely eroded due to deuterium bombardment on plasma facing surfaces in the initial phase of discharges and trapped highest amount of deuterium. Lower deuterium retention has been found in the inner divertor sample, which is presumably due to the particular exposure history in the 2010 spring campaign.

关键词： deuterium retention post-mortem analyses SiC-coated graphite tiles EAST

Optical diagnostics of femtosecond laser plasmas

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Science China Mathematics 2001年第1期44卷 98-102页

作者：李玉同张杰陈黎明夏江帆腾浩赵理曾林景全李英骏魏志义王龙江文勉 Institute of Physics Chinese Academy of Sciences Research center of Laser fusion Academy of Engineering Physics

Optical diagnostics of evolution of plasmas produced by ultrashort laser pulses is carried out using a femtosecond probing beam. The time sequence of plasma shadowgrams and interferograms are obtained. The filamentation instability in high-density region induces the local density modification. Large-scale toroidal magnetic fields confine plasma expansion in the transverse direction, resulting in the formation of a plasma jet. The plasma expansion along the target normal direction is found to scale as t1/2.

关键词： Femtosecond laser plasma Optical diagnostic Electron density gradient

Succession law of Nd–Fe–B alloys with different coercivities

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Rare Metals 2015年第9期34卷 657-661页

作者： Jie Tang Li-Rong Yang Lin Zhang Cheng-Fu Wei Yang Mei Yong-Ge Wen School of Chemistry and Chemical Engineering Mianyang Normal University Research center of Laser fusion China Academy of Engineering Physics

In order to establish a succession law of every phase in sintered Nd–Fe–B magnets marked as 38/38H/38SH/38 UH, four alloys of Nd33-xDyxAl0.7Nb0.6Cu0.1B1.05 Fe bal.(at%) were investigated after smelting processing, sintering processing, high-temperature tempering processing, and highand low-temperature tempering processing. It is found that the four phases: the Nd2Fe14B matrix phase, Nd-rich phase,B-rich phase, and defect phase can be inherited by means of the subsequent processing. These phases might have the special constitution and appearance in the different *** properties also have succession law. In every processing except smelting one, the values of remanence and maximum energy product hardly alter, but the value of coercive force increases gradually.

关键词： Nd–Fe–B alloy Phase Succession magnetic property M

Optimization of X-mode electron cyclotron current drive in high-electron-temperature plasma in the EAST tokamak

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Plasma Science and Technology 2023年第2期25卷 47-57页

作者：王瀚林邹晓岚王晓洁 Yves PEYSSON 李妙辉吴陈斌张超刘甫坤 Joan DECKER Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People's Republic of China University of Science and Technology of China Hefei 230026People's Republic of China CEA Institute for Magnetic Fusion ResearchSaint-Paul-Lez-Durance F-13108France EPFL Swiss Plasma CenterLausanne 1018Switzerland

A discharge with electron temperature up to 14 keV has been achieved in *** of the electron cyclotron current drive(ECCD)efficiency at high electron temperature under EAST parameters is presented using C3PO/LUKE *** results show that the ECCD efficiency of X-mode increases with central electron temperature up to 10 keV and then starts to decrease above 10 keV,at a specific magnetic field and toroidal *** efficiency degradation is due to the presence of the third harmonic extraordinary(X3)downshifted absorption at the low field side(LFS);even the cold resonance of X3 mode is located outside the *** the electron temperature increases from 5 to 20 ke V,the X3 absorption increases from 0.9%to 96.4%.The trapping electron effect at the LFS produces a reverse Ohkawa *** competition between the Fisch–Boozer current drive and the Ohkawa current drive results in a decrease in ECCD *** efficiency optimization is achieved through two *** is to increase the toroidal angle,leading to X2 mode predominating again over X3 mode and the electron resonance domain of X2 mode moving far from the trapped/passing *** second one is to increase the magnetic field to move away the X3 resonance layer from the plasma,hence less EC power absorbed by X3 mode.

关键词： current drive ECCD efficiency EAST tokamak

Effects of resonant magnetic perturbations on the loss of energetic ions in tokamak pedestal

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Plasma Science and Technology 2020年第10期22卷 52-61页

作者： Haotian HUANG Lu WANG International Joint Research Laboratory of magnetic Confinement fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People's Republic of China

Resonant magnetic perturbations(RMPs) are extensively applied to mitigate or suppress the edge localized mode in tokamak plasmas, but will break the axisymmetric magnetic field configuration and increase the loss of energetic ions. The mechanism of RMPs induced energetic ion loss has been extensively studied, and is mainly attributed to resonant effects. In this paper,in the perturbed non-axisymmetric tokamak pedestal, we analytically derive the equations of guiding center motion for energetic ions including the bounce/transit averaged radial drift velocity and the toroidal precession frequency modified by strong radial electric field. The loss time of energetic ions is numerically solved and its parametric dependence is analyzed in *** find that passing energetic ions cannot escape from the plasma, while deeply trapped energetic ions can escape from the plasma. The strong radial electric field plays an important role in modifying the toroidal precession frequency and resulting in the drift loss of trapped energetic ions. The loss time of trapped energetic ions is much smaller than the corresponding slowdown time in DIII-D pedestal. This indicates that the loss of trapped energetic ions in the perturbed non-axisymmetric pedestal is important, especially for the trapped energetic ions generated by perpendicular neutral beam injection.

关键词： resonant magnetic perturbations non-axisymmetric magnetic field energetic ions drift loss radial electric field

3D electromagnetic modelling for high-temperature superconducting dynamo flux pumps using T-A formulation

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High Voltage 2024年第2期9卷 367-379页

作者： Luning Hao Fangliang Dong Jintao Hu Qi Wang Haigening Wei Ismail Patel Adil Shah Yuyang Wu Tim Coombs Department of Engineering University of CambridgeCambridgeUK Plasma Science and fusion center Massachusetts Institute of TechnologyCambridgeMassachusettsUSA

A high-temperature superconducting(HTS)dynamo flux pump can inject DC currents into closed-loop HTS magnets without *** enables the realisation of current-lead-free or even through-wall charging systems for high-field applications such as nuclear magnetic resonance/magnetic resonance imaging(MRI)magnets,fusion reactors and *** have proposed many simulation models to understand the working principle of HTS dynamos,few of which are in 3D because of converging ***,the influences of many key 3D parameters in the HTS dynamo are scarcely *** authors propose an efficient 3D modelling method of the HTS dynamo based on the T-A *** rotating magnets are modelled by a ring-shaped permanent magnet with space-time-variant remanent flux density to avoid moving ***,together with the T-A formulation,makes the 3D model efficient and *** accuracy of the model is verified by the experimental instantaneous and time-integrated dynamic *** this model,the authors present systematic case studies to thoroughly explore the influences of the key parameters of a dynamo flux pump on the dynamic voltage and *** proposed modelling method and results could significantly benefit the design and optimisation of HTS dynamos for high-field magnets.

关键词： formulation magnets pump

Hydrogen Adsorption on Ti Decorating Benzene Grafted Tetrahydrido-silsequioxanes

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Chinese Journal of Structural Chemistry 2012年第4期31卷 459-466页

作者：李晓东张红唐永建吴卫东王朝阳 College of Physical Science and Technology Sichuan University Research center of Laser fusion China Academy of Engineering Physics

A novel type of Ti decorating benzene grafted tetrahydrido-silsequioxane struc-tures was designed and investigated using density functional theory（DFT）.The hydrogen adsorption properties of this new material were investigated at the same level of *** results reveal that up to four hydrogen molecules（with the restrict of 18 electrons rule） can be adsorbed on each Ti atom of（TiC6H5）m-H4-mSi4O6（m = 1-4） molecular systems with the average binding energies of 0.691,0.692,0.693 and 0.695 eV for m = 1-4,*** variations of HOMO- LUMO energy gaps verify that the host structures with four H2 molecules adsorbed own the best kinetics *** interaction mechanism of H2 molecules with the host materials mainly attributes to the well-known ＂kubas interactions＂.All the results indicate that the complex structures designed here may be used as hydrogen storage materials at ambient conditions.

关键词： tetrahydrido-silsequioxane density functional theory hydrogen storage adsorption

Density Functional theory Study of MoO_3 Molecule Encapsulated inside Single-walled Carbon Nanotubes

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Chinese Journal of Structural Chemistry 2012年第11期31卷 1634-1640页

作者：李瑞唐永建张红 College of Physical Science and Technology Sichuan University Research center of Laser fusion China Academy of Engineering Physics

The binding energies, geometric structures and electronic properties of molybde- num trioxide （MOO3） molecule encapsulated inside （8, 0）, （9, 0）, （10, 0） and （14, 0） single-walled carbon nanotubes （SWNTs） have been investigated using density functional theory （DFT） method. Due to curvature effect, the calculated binding energy values are different, the variation of which indicated that the stability of MoO3/SWNT systems increases with increasing the radius of SWNTs. At the same time, owing to the presence of MoO3 molecule, the band gap of MoO3/SWNTs systems decreases. The analysis of density of states （DOS） reveals hybridization between C-2p and Mo-4d and between C-2p and O-2p orbitals near the Fermi level, which results in electron transfer from SWNTs to MoO3 molecule. The present computations suggest that electronic properties of SWNTs can be modified by doping MoO3 molecule.

关键词： MoO3 molecule single-walled carbon nanotubes density functional theory