The electrochemical reduction of solid TiO2 directly to solid metal is a promising alternative to the current Kroll process. The present work is aimed at studying the effect of electrolysis voltage on the rate of elec...The electrochemical reduction of solid TiO2 directly to solid metal is a promising alternative to the current Kroll process. The present work is aimed at studying the effect of electrolysis voltage on the rate of electrochemical reduction. The products of electrochemical reduction of TiO2 and Ti2O were examined using the scanning electron microscopy （SEM） and X-ray diffraction （XRD） techniques. The results show that Ti2O was reduced to low valent titanium oxide at 1.5 -1.7 V, which was the result of ionization of oxygen. TiO2 and Ti20 were reduced to titanium metal at 2.1-3.1 V, which was the co-action of ionization of oxygen and calciothermic reduction. The oxygen content decreased rapidly with voltage increasing from 2.1 to 2.6 V, while it changed little from 2.6 to 3.1 V. The optimized cell voltage was 2.6-3.1 V.展开更多
The effects of fluoride ions(F^(-)) on the electrochemical behavior and coordination properties of titanium ions(Ti^(n+)) were studied in this work,by combining electrochemical and mathematical analysis as well as spe...The effects of fluoride ions(F^(-)) on the electrochemical behavior and coordination properties of titanium ions(Ti^(n+)) were studied in this work,by combining electrochemical and mathematical analysis as well as spectral techniques.The α was taken as a factor to indicate the molar concentration ratio of F^(-) and Ti^(n+).Cyclic voltammetry(CV),square wave voltammetry(SWV),and open circuit potential method(OCP)were used to study the electrochemical behavior of titanium ions under conditions of various α,and in-situ sampler was used to prepare molten salt samples when α equal to 0.0,1.0,2.0,3.0,4.0,5.0,6.0,and 8.0.And then,samples were analyzed by X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy.The results showed that F^(-) in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable.Ti^(2+) cannot be detected in the molten salt when α is higher than 3.0 and finally transferred to titanium ions with higher valence state.Investigation revealed that the mechanism behind those phenomenon is the coordination compounds(TiCl_(j) F_(i)^(m-)) forming.展开更多
The mechanism of the electrochemical reduction of niobium ions in molten NaF-CaF_2 (2 : 1 mol) wasinvestigated by means of cyclic voltammetry and chronoamperometry. It is found that the reduction ofNb ( V ) proceedsi...The mechanism of the electrochemical reduction of niobium ions in molten NaF-CaF_2 (2 : 1 mol) wasinvestigated by means of cyclic voltammetry and chronoamperometry. It is found that the reduction ofNb ( V ) proceedsintwosteps : Nb ( V)→ Nb (Ⅳ)→Nb ( 0 ) . Theelectrochmical reaction Nb ( Ⅳ) + 4e →Nb( 0 ) is a reversible and diffusion-controlled process.展开更多
The cathodic electrode process of Y^(3+) ions on the Mo electrode in the LiCl-KCl molten salt with YCl_3(3wt%) in the temperature range of 450～530℃ has been investigated using cyclic voltammetry and chronopotentiome...The cathodic electrode process of Y^(3+) ions on the Mo electrode in the LiCl-KCl molten salt with YCl_3(3wt%) in the temperature range of 450～530℃ has been investigated using cyclic voltammetry and chronopotentiometry.The convolution technique has been applied to the treatment of cyclic voltammogram.The results show that the reduction mechanism of Y^(3+) ion is Y^(3+)+3e=Y,a simple one-step process.The cathodic process is very close to a reversible process under lower scanning rates,and is diffusion-controlled.The cathodic product is an insoluble product.展开更多
The oxygen-ion-permeable membrane galvanic short-circuit method has been developed, in which pure metal was directly extracted from the molten oxide slag, and no external voltage is applied. The galvanic cell employed...The oxygen-ion-permeable membrane galvanic short-circuit method has been developed, in which pure metal was directly extracted from the molten oxide slag, and no external voltage is applied. The galvanic cell employed in the experiment was as follows: graphite rod|[O]Fe+C saturation|ZrO2(MgO)|(FeO)(slag)|Fe rod. The reduction current in the galvanic cell consisted of an external short-circuit current and an interior short-circuit current in the oxygen-ion-permeable membrane. The real-time variation of external circuit reduction ratio of the molten slag could be obtained from the curve of the external circuit current to the time.展开更多
The oxygen-ion-permeable membrane galvanic short-circuit method has been developed, in which pure metal was directly extracted from the molten oxide slag, and no external voltage is applied. The galvanic cell employed...The oxygen-ion-permeable membrane galvanic short-circuit method has been developed, in which pure metal was directly extracted from the molten oxide slag, and no external voltage is applied. The galvanic cell employed in the experiment was as follows: graphite rod|[O][ZrO(MgO)|(FeO))|Fe rod. The reduction current in the galvanic cell consisted of an external short-circuit current and an interior short-circuit current in the oxygen-ion-permeable membrane. The real-time variation of external circuit reduction ratio of the molten slag could be obtained from the curve of the external circuit current to the time.展开更多
The mechanism of the cathodic process of Y(Ⅲ) on platinum and molybdenum electrode in molten LiF YF 3 Y 2O 3 was investigated by means of cyclic voltammetry. The number of electron transferred was calculated. Th...The mechanism of the cathodic process of Y(Ⅲ) on platinum and molybdenum electrode in molten LiF YF 3 Y 2O 3 was investigated by means of cyclic voltammetry. The number of electron transferred was calculated. The results show that the electrochemical reduction of Y(Ⅲ) is a reversible one step three electrons reaction and the cathodic process is diffusion controlled. The reductive product easily forms the intermetallic compounds with the platinum electrode, but it is pure yttrium on the molybdenum electrode.展开更多
The mechanism of the cathode reduction of Ti(Ⅳ) at platinum electrode in molten LiF-NaF containingvarious concentrations of K_2TiF_6 has been investigated by means of cyclic voltamrnetry and convolutiontechnique. The...The mechanism of the cathode reduction of Ti(Ⅳ) at platinum electrode in molten LiF-NaF containingvarious concentrations of K_2TiF_6 has been investigated by means of cyclic voltamrnetry and convolutiontechnique. The transfered electron number of each reduction step has been determined. It is found that thereduction of Ti(Ⅳ) proceeds in three steps: Ti(Ⅳ)→Ti(Ⅲ)→Ti(Ⅱ)→Ti(0). The first step is accompanied bythe chemical disproportionation reaction: ZTi(Ⅲ)→Ti(Ⅳ)+Ti(Ⅱ). The cathodic product is soluble and prob-ably forrns alloy with the platinurn electrode.展开更多
基金the Postdoctoral Science Foundation of China (No. 20060400409).
文摘The electrochemical reduction of solid TiO2 directly to solid metal is a promising alternative to the current Kroll process. The present work is aimed at studying the effect of electrolysis voltage on the rate of electrochemical reduction. The products of electrochemical reduction of TiO2 and Ti2O were examined using the scanning electron microscopy （SEM） and X-ray diffraction （XRD） techniques. The results show that Ti2O was reduced to low valent titanium oxide at 1.5 -1.7 V, which was the result of ionization of oxygen. TiO2 and Ti20 were reduced to titanium metal at 2.1-3.1 V, which was the co-action of ionization of oxygen and calciothermic reduction. The oxygen content decreased rapidly with voltage increasing from 2.1 to 2.6 V, while it changed little from 2.6 to 3.1 V. The optimized cell voltage was 2.6-3.1 V.
基金financially supported by the National Natural Science Foundation of China(No.51804277)the State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization,China(No.CNMRCUKF2008)+1 种基金the State Key Laboratory of Special Rare Metal Materials,China(No.SKL2020K004)the Northwest Rare Metal Materials Research Institute,China。
文摘The effects of fluoride ions(F^(-)) on the electrochemical behavior and coordination properties of titanium ions(Ti^(n+)) were studied in this work,by combining electrochemical and mathematical analysis as well as spectral techniques.The α was taken as a factor to indicate the molar concentration ratio of F^(-) and Ti^(n+).Cyclic voltammetry(CV),square wave voltammetry(SWV),and open circuit potential method(OCP)were used to study the electrochemical behavior of titanium ions under conditions of various α,and in-situ sampler was used to prepare molten salt samples when α equal to 0.0,1.0,2.0,3.0,4.0,5.0,6.0,and 8.0.And then,samples were analyzed by X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy.The results showed that F^(-) in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable.Ti^(2+) cannot be detected in the molten salt when α is higher than 3.0 and finally transferred to titanium ions with higher valence state.Investigation revealed that the mechanism behind those phenomenon is the coordination compounds(TiCl_(j) F_(i)^(m-)) forming.
文摘The mechanism of the electrochemical reduction of niobium ions in molten NaF-CaF_2 (2 : 1 mol) wasinvestigated by means of cyclic voltammetry and chronoamperometry. It is found that the reduction ofNb ( V ) proceedsintwosteps : Nb ( V)→ Nb (Ⅳ)→Nb ( 0 ) . Theelectrochmical reaction Nb ( Ⅳ) + 4e →Nb( 0 ) is a reversible and diffusion-controlled process.
基金This project is supported by the National Natural Science Foundation of China
文摘The cathodic electrode process of Y^(3+) ions on the Mo electrode in the LiCl-KCl molten salt with YCl_3(3wt%) in the temperature range of 450～530℃ has been investigated using cyclic voltammetry and chronopotentiometry.The convolution technique has been applied to the treatment of cyclic voltammogram.The results show that the reduction mechanism of Y^(3+) ion is Y^(3+)+3e=Y,a simple one-step process.The cathodic process is very close to a reversible process under lower scanning rates,and is diffusion-controlled.The cathodic product is an insoluble product.
基金This work was financially supported by the National Natural Science Foundation of China (No.59934090) and the National Key Basic Research and Development Program of China (No.G1998061506)
文摘The oxygen-ion-permeable membrane galvanic short-circuit method has been developed, in which pure metal was directly extracted from the molten oxide slag, and no external voltage is applied. The galvanic cell employed in the experiment was as follows: graphite rod|[O]Fe+C saturation|ZrO2(MgO)|(FeO)(slag)|Fe rod. The reduction current in the galvanic cell consisted of an external short-circuit current and an interior short-circuit current in the oxygen-ion-permeable membrane. The real-time variation of external circuit reduction ratio of the molten slag could be obtained from the curve of the external circuit current to the time.
文摘The oxygen-ion-permeable membrane galvanic short-circuit method has been developed, in which pure metal was directly extracted from the molten oxide slag, and no external voltage is applied. The galvanic cell employed in the experiment was as follows: graphite rod|[O][ZrO(MgO)|(FeO))|Fe rod. The reduction current in the galvanic cell consisted of an external short-circuit current and an interior short-circuit current in the oxygen-ion-permeable membrane. The real-time variation of external circuit reduction ratio of the molten slag could be obtained from the curve of the external circuit current to the time.
文摘The mechanism of the cathodic process of Y(Ⅲ) on platinum and molybdenum electrode in molten LiF YF 3 Y 2O 3 was investigated by means of cyclic voltammetry. The number of electron transferred was calculated. The results show that the electrochemical reduction of Y(Ⅲ) is a reversible one step three electrons reaction and the cathodic process is diffusion controlled. The reductive product easily forms the intermetallic compounds with the platinum electrode, but it is pure yttrium on the molybdenum electrode.
文摘The mechanism of the cathode reduction of Ti(Ⅳ) at platinum electrode in molten LiF-NaF containingvarious concentrations of K_2TiF_6 has been investigated by means of cyclic voltamrnetry and convolutiontechnique. The transfered electron number of each reduction step has been determined. It is found that thereduction of Ti(Ⅳ) proceeds in three steps: Ti(Ⅳ)→Ti(Ⅲ)→Ti(Ⅱ)→Ti(0). The first step is accompanied bythe chemical disproportionation reaction: ZTi(Ⅲ)→Ti(Ⅳ)+Ti(Ⅱ). The cathodic product is soluble and prob-ably forrns alloy with the platinurn electrode.
基金the financial support from the Natural Science Foundation of Anhui Province, China (No. 2008085ME170)the Anhui Special Support Plan, China (No. T000609)the National Natural Science Foundation of China (No. 51204002
基金supports from the National Key Research and Development Program of China (No.2021YFC2901600)supported by the State Key Laboratory of Special Rare Metal Materials (No.SKL2020K004)。
