Materials Today Communications
·
2021
·
IF 3.383
Jinzhao Guan,Kaiyu Xie,Aimin Liu,Zhongning Shi,Gong Chen,Miroslav Boca
In this study, Al–Si alloy, a precursor of the solar-grade silicon , was prepared via the aluminothermic reduction–molten salt electrolysis of SiO 2 in KF–AlF 3 molten salt by employing liquid aluminum as the working cathode. The reaction mechanism of the aluminothermic reduction of SiO 2 in KF–AlF 3 molten salt at 750 °C was determined by thermogravimetry–differential scanning calorimetry. The reaction rate equation for the aluminothermic reduction of SiO 2 in KF–AlF 3 molten salt was: d α dt = 7.156 × 10 24 e − 4.688 × 10 5 RT ( 1 − α ) 1.734 . In 49.4 wt% KF–47.6 wt% AlF 3 –3 wt% SiO 2 molten salt at 750 °C, the Si content in the Al–Si alloy obtained by the aluminothermic reduction–molten salt electrolysis of SiO 2 was 24.53 wt%. Compared with solely aluminothermic reduction of SiO 2 , the current efficiency in the process of the aluminothermic reduction–molten salt electrolysis of SiO 2 was evaluated. The results reveal that the Al–Si alloy is predominantly prepared in the aluminothermic reduction step, while supplemented by electrolysis. The calculated Faradic current efficiency of the proposed aluminothermic reduction–molten salt electrolysis process was 28.4%.
研究领域:
材料科学
·
冶金工程
✓ 已验证
产品关联
DOI
高影响因子
Materials Research Express
·
2022
·Vol. 9
·期 6
·065505
·
IF 2.025
Qinghong You,Xiulian Yin,Jun Wang,Chunhua Dai
A recyclable heterogeneous KF/Ca-Mg-Al-O catalyst was prepared by co-precipitation and calcination processes. The characteristics of the catalyst were investigated using FTIR, XRD, TG-DTG and SEM. Response surface methodology was utilized to obtain the best most extreme biodiesel production yield. The ideal biodiesel production conditions were: the amount of catalyst was 3 wt%; the reaction temperature was 65 °C; the alcohol oil molar ratio 9.8:1, the reaction time was 3.5 h. Under these amended conditions, the average biodiesel yield was 95.19%, which is well in close concurrence with the worth anticipated by the model. The repeatability of catalysts was studied. After using the catalyst seven times, the catalytic efficiency was only reduced by 2.7%. These results indicate that the catalyst has good catalytic efficiency and is recyclable.
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Inorganic and Organometallic Polymers and Materials
·
2019
·Vol. 29
·期 6
·2003-2011
·
IF 1.637
Hua Rui,Li He,Liu Xiao-Qin,Liu Ding-Hua
With an increasing demand for green chemistry and sustainable development, it is needed to design a solid base with high catalytic activity, excellent stability and reusability. In this work, a new kind of magnetic solid basic catalyst KF/CaO–CoFe 2 O 4 was prepared by the method including co-precipitation and isochoric impregnation, and it was successfully applied in the preparation of polycarbonate diol (PCDL) from the transesterification of 1,4-butanediol with dimethyl carbonate. The characteristics and properties of the catalyst were examined and analyzed by XRD, TEM, CO 2 -TPD and VSM. The effects of various parameters such as shell-core mole ratio, KF loading, calcination temperature, catalyst dosage, and the mole ratio of the raw materials on the yield of PCDL were investigated and the yield of PCDL can reach to 71.2% under the optimal reaction conditions. In addition, the catalyst can be easily separated by an external magnet after reaction, and the catalytic activity of the catalyst can well be maintained for 4 cycles.
研究领域:
化学工程
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材料科学
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催化
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
INORGANIC CHEMISTRY
·
2025
·
IF 4.7
Ming Lin,Yihong Liu,Jinzhao Guan,Yunliang Li,Mouhamadou Aziz Diop,Dianbao Feng,Yikun Ren,Yixiao Kang,Shifang Ma,Yujun Li,Fenghui An,Xianwei Hu
The KF-ZrF4 molten salt system has emerged as a promising candidate solvent for fourth-generation reactor designs, where its physicochemical characteristics are fundamentally governed by the ionic structure within the molten fluoride matrix. A variety of complex Zr–F ions, including ZrF5–, ZrF62–, ZrF73–, and ZrF84–, were identified in KF-ZrF4 molten salts with different molar ratios through Raman spectroscopy and quantum chemical calculations. Furthermore, the Zr2F9– ion with a bridging F structure was discovered in KF-ZrF4 molten salts with molar ratios of 1 and 0.65, and the experimental Raman spectrum of this ion was obtained. At higher KF to ZrF4 molar ratios of 5.7 and 2.3, ZrF73– and ZrF84– dominated, while ZrF5– and ZrF84– were predominant at molar ratios of 1 and 1.5. At a lower ratio of 0.67, ZrF5– emerged as the primary species. As the KF to ZrF4 molar ratio decreased, the system favored the formation of less-coordinated Zr–F ions. Moreover, a dynamic mutual transformation equilibrium existed among these complex ions, and this equilibrium was influenced by the zirconium fluoride content in the molten salt. Quantum electrochemical analysis revealed that ZrF5– was mainly involved in the cathode reaction. Zr4+ was first released from ZrF5–, gaining three electrons to form Zr+. Subsequently, Zr+ gained one electron, transforming into metallic zirconium at the cathode interface. These findings deepen our understanding of the physicochemical properties of molten salt reactors and have significant implications for advanced applications in metal purification, spent nuclear fuel recovery, and zirconium alloy production, thereby contributing to improved nuclear materials management and energy sustainability.
研究领域:
核材料科学
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熔盐化学
·
电化学
·
光谱学
·
量子化学
·
核能工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ELECTROCHIMICA ACTA
·
2024
·
IF 5.5
Biwu Cai,Jianbang Ge,Zichen Zhang,Yang Gao,Shun Cao,Zhihao Cheng,Xin Lu,Shuqiang Jiao
Understanding mass transfer is of great importance to molten salt electrochemistry. However, natural convection has long been neglected in electrochemical measurements in stagnant molten salt systems due to the complex mathematical treatments. Here we reported the notable natural convection effects in molten LiF-NaF-KF during cyclic voltammetry and chronoamperometry tests. The established model showed that the convection-diffusion layer (CDL) convection dominated mass transfer under long time-scale tests in molten LiF-NaF-KF-EuF 3 . However, in the case of molten LiF-NaF-KF-K 2 TiF 6 , CDL convection predominated at dilute redox concentrations while density-driven convection came into dominance at high redox concentrations, because of the severe coordinate structure change of the redox couple. The derived thickness of the convection-diffusion layer, δ c o n v . , ranged from 135 to 183 μm, much higher than that in aqueous solutions (220–250 μm). Moreover, the increase in system temperature greatly enhanced natural convection effects in molten fluorides. Lastly, the use of microelectrode (re<39.7 μm for δ c o n v . =160 μm) was demonstrated to be an effective way to suppress the intense natural convection effects.
研究领域:
电化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
·
2011
·Vol. 42
·期 5
·1065-1070
·
IF 0.974
Yan Hengwei,Yang Jianhong,Li Wangxing,Chen Shazi
KF-NaF-AlF 3 -based electrolyte is a promising low-temperature electrolyte for aluminum reduction. Alumina solubility in molten KF-NaF-AlF 3 -based electrolyte was determined as a function of the melt composition and temperature by measuring the weight loss of a rotating corundum disk and by using a LECO RO500 oxygen analyzer (LECO Corporation, St. Joseph, MI). The investigated temperature range is 1023 K to 1073 K (750 °C to 800 °C), and the total cryolite molar ratio (CRt = ([KF] + [NaF])/[AlF 3 ]) is 1.3 to 1.5; the content of NaF ranges from 0 mol pct to 50 mol pct. The effect of temperature, CaF 2 , and LiF on alumina solubility is discussed as well.
研究领域:
冶金学
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材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2011
·
IF 2.089
Hengwei Yan,Jianhong Yang,Wangxing Li
The surface tension and density of molten KF–NaF–AlF3-based electrolytes were determined as a function of the melting composition and temperature by the Archimedean method and maximum bubble-pressure method, respectively. The investigated temperatures range from (1013 to 1103) K, and the total cryolite molar ratio (CRt = ([KF] + [NaF])/[AlF3]) is 1.3 to 1.41; the mole fraction of NaF ranges from 0.15 to 0.4. The effects of temperature and the content of CaF2 and Al2O3 on surface tension and density were also investigated. The results indicate that the density and the surface tension tend to increase with the NaF content and CRt. The density and the surface tension fit the linear relationship with temperature.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED ELECTROCHEMISTRY
·
2024
·
IF 2.4
Li Mei,Du Rui,Wei Hedi,Chen Jiayi,Liu Rugeng,Zhang Meng,Han Wei
In order to investigate the influences of the additive (KF) on electrochemistry and deposit morphology of Pr, various electrochemical techniques were used to comparative investigate the electroreduction potential and diffusion coefficient of Pr 3+ and kinetic properties of Pr 3+ /Pr in LiCl–KCl-PrCl 3 before and after the addition of KF at different molar concentration ratios of F − to Pr 3+ ( k ). Cyclic voltammetry, square wave voltammetry, and reverse chronopotentiometry results showed that the value of k ( k = 0, 1, 2, 3, and 4) had no effect on reduction mechanism of Pr 3+ . With the increase of k , the reduction peak potential moved in the negative direction, the diffusion coefficient decreased, and diffusion activate energy increased. Meanwhile, the exchanged current densities ( j 0 ), charge transfer resistances ( R ct ), and activate energies ( E a ) were measured at different k by linear polarization technique, which illustrated that with the increase of k , j 0 gradually decreased, and E a and R ct increased. Furthermore, the electrochemical preparation of Pr aided by KF was explored by potentiostatic electrolysis at different k , and the products were characterized by XRD, SEM, and EDS, which indicated that with the increase of k , the morphology of metallic Pr changed from slender needles to granular. Graphical abstract
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2015
·Vol. 162
·期 4
·C197
·
IF 3.266
Gong Chen,Zhongning Shi,Jiangyu Yu,Junli Xu,Xianwei Hu,Zhaowen Wang,Bingliang Gao
The passivation of a graphite electrode in LiF–KF molten salt at 773 K was studied using cyclic voltammetry and electrochemical impedance spectroscopy. The anodic cyclic voltammogram showed that there are two oxidation current peaks at approximately 1.2 and 4.8 V vs. Pt quasi-reference electrode. We confirmed that carbon fluoride compounds are formed at the first current peak, while the last current peak was predominantly attributed to F2 evolution. The surfaces of the anodes used for electrolysis were analyzed at the potential of 1.0 V by X-ray photoelectron spectroscopy and Raman spectroscopy, and the anode atmosphere during the experiments was analyzed by gas chromatography. The results show that solid carbon fluoride compounds were formed in the graphite surface and no trace of gaseous carbon fluoride was detected. In addition, the active–passive transition of graphite electrode was observed in the EIS spectra recorded at 1.5 V. We confirmed the reason for the passivation of a graphite anode in LiF–KF molten salt: the formed carbon fluoride compounds layer blocks the transmission of F− anion from the electrolyte to the graphite electrode.
研究领域:
电化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2020
·Vol. 104
·期 2
·824-832
·
IF 3.502
Dashuang Ding,Yanlong Wang,Changgui Lin,Jing Ren,Wenbo Shi,Pengyuan Wang,Bing Yang,Shaoqian Zhang,Liping Duo
Incorporation of transition-metal ions (TMIs) in the precipitated nanocrystals (NCs) of glass-ceramics (GCs) greatly improves the photonic properties of these materials. The crystal field and coordination of TMIs show fingerprints for spectroscopic characterization. However, it is difficult to probe the effect of the host NCs’ structural phase on doped TMIs’ d-d orbitals. Herein, ZnF 2 :Ni and KZnF 3 :Ni based on controllable crystallization in KF-ZnF 2 -SiO 2 :Ni 2+ GCs were taken as model systems. Compared to ZnF 2 , perovskite-type KZnF 3 has higher binding energy Zn-F bonds in which Ni 2+ are easier to be segregated, which makes KZnF 3 :Ni be better “excited electron trapper” due to hole localization to intra-gap Ni states. These findings contribute to the understanding and design of TMIs-doped GCs in practical applications.
研究领域:
材料科学
·
光子学
·
固态化学
·
纳米材料
·
光学材料
✓ 已验证
DOI
高影响因子
iScience
·
2021
·
IF 5.458
Yu-Qing Guan,Xiang-Ting Min,Gu-Cheng He,Ding-Wei Ji,Shi-Yu Guo,Yan-Cheng Hu,Qing-An Chen
Summary Ritter reaction has been recognized as an elegant strategy to construct the C−N bond. Its key feature is forming the carbocation for nucleophilic attack by nitriles. Herein, we report a complementary visible-light-induced three-component Ritter reaction of alkenes, nitriles, and α -bromo nitriles/esters, thereby providing mild and rapid access to various γ -amino nitriles/acids. Mechanistic studies indicated that traceless fluoride relay, transforming KF into imidoyl fluoride intermediate, is critical for the efficient reaction switch from atom transfer radical addition (ATRA) to the Ritter reaction. This approach to amino-alkylation of alkenes is chemoselective and operationally simple.
研究领域:
有机化学
·
合成化学
✓ 已验证
DOI
高影响因子
CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2019
·Vol. 35
·期 4
·721-728
·
IF 1.071
Shen Xiaolong,Liu Shaoying,Wang Qingyin,Zhang Hua,Wang Gongying
MgO loaded with KF was prepared by using the impregnation method and was employed as the catalyst for the direct transesterification of diphenyl carbonate(DPC) with isosorbide to synthesize high-molecular-weight poly(isosorbide carbonate)(PIC). The relationship between physical-chemical properties and catalytic performance for KF/MgO in this melt process was investigated by various characterization techniques. The basic site amount and strength were found to be responsible for this transesterification process, and the medium and strong basic sites tended to promote the polycondensation reaction. 20-KF/MgO-500 exhibited the best catalytic performance, giving PIC with M w of 84200 and glass transition temperature( T g ) of 173 °C under optimal conditions. Additionally, 20-KF/MgO-500 was found to catalyze the transerification of DPC with isosorbide and other diols to synthesize the corresponding poly(aliphatic diol-co-isosorbide carbonate)s(PAICs). This excellent activity can be ascribed to the presence of an abundance of basic sites and their specific basic strength on the surface of KF/MgO.
研究领域:
高分子科学
·
材料化学
·
催化
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）