Influence of mass transfer and electrolyte composition on anodic oxygen evolution in molten oxides

Caldwell, Andrew H.; Lai, Erica; Gmitter, Andrew J.; Allanore, Antoine

doi:10.1016/j.electacta.2016.09.132

Cited by 15 publications

(21 citation statements)

References 10 publications

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“…Other high melting point metals such as titanium and zirconium are not chemically stable in the slag as they can reduce metals from oxide species within the melt. Iridium has been intensively studied in MOE [7,17,19,22], where it has been demonstrated to act as an oxygen-evolving anode [7]. While the price of iridium is too high for large-scale applications, iridium plays an important role in laboratory scale studies.…”

Section: Electrochemical Measurements and Analysismentioning

confidence: 99%

“…This type of reference electrode is commonly used in MOE when performing three-electrode measurements [7,9,17,19,22], where it provides a constant potential and has the advantage of having a low impedance [23]. However, its potential cannot be calculated thermodynamically as the species in equilibrium at the pseudo-reference electrode are unknown.…”

Section: Electrochemical Measurements and Analysismentioning

confidence: 99%

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Electrochemical behaviour of titanium-bearing slag relevant for molten oxide electrolysis

Martin-Treceno

Weaver

Allanore

et al. 2020

Electrochimica Acta

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A containerless approach was used to investigate the electrochemical behaviour of TiO 2 -SiO 2 -Al 2 O 3 -MgO -CaO slags in their molten state. Iridium was used in a three-electrode configuration to perform a combination of electrochemical techniques inside a modified thermal imaging furnace. The real-time visualisation during experimentation and the post-mortem microscopy analysis confirmed the direct production of an Ir−Ti−Si alloy and the evolution of oxygen during electrolysis. Thermodynamic properties of the slag were predicted with FactSage and were consistent with experiment. The results justify the use of this method to better characterize the potential of these systems as a secondary source of materials.

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Section: Electrochemical Measurements and Analysismentioning

confidence: 99%

Section: Electrochemical Measurements and Analysismentioning

confidence: 99%

Electrochemical behaviour of titanium-bearing slag relevant for molten oxide electrolysis

Martin-Treceno

Weaver

Allanore

et al. 2020

Electrochimica Acta

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“…Moreover, Ir does not react with the slag or oxidise under the experimental conditions, [2] and has been successfully used as electrodes in the electrolysis of molten oxides before. [2,15,17] All the electrochemical measurements were conducted using a potentiostat (Gamry Reference 3000). Each measurement began by recording the OCP.…”

Section: B Electrochemical Measurements and Operationmentioning

confidence: 99%

Determination of the Partial Contributions to the Electrical Conductivity of TiO2-SiO2-Al2O3-MgO-CaO Slags: Role of the Experimental Processing Conditions

Martin-Treceno

Allanore

Bishop

et al. 2022

Metall Mater Trans B

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The electrical transport properties of molten TiO2–SiO2–Al2O3–MgO–CaO slags were determined as a function of temperature and oxygen partial pressure. To avoid the corrosion of crucible materials by this slag at ultra high temperatures, the pendant droplet technique was used inside a modified floating zone furnace. Electronic and ionic transference numbers were estimated using stepped-potential chronoamperometry experiments to quantify the contribution of the electronic/ionic conductivity to the total electric conductivity. The results show that these slags are mixed conductors, where current is carried by ionic and electronic carriers. The oxygen partial pressure dependence of the electronic transference numbers, $$t_e$$ t e , indicated a semiconducting mechanism in the molten slag. The ratio of the different valences of the transition metal ions had a predominant effect on the $$t_e$$ t e . The $${{\text{TiO}}_{2}}$$ TiO 2 content also favoured electronic conduction, while the effect of temperature and structure was less noticeable within the temperature and composition range studied.

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“…The anode yields around 100 pct in Fe#5 to Fe#10 indicate that the oxidation of oxide anions, reaction [19], can be the exclusive anode half reaction, which is coherent with results obtained elsewhere. [26,27] Then, the electroactive species is presumed to be free oxygen anions. [28] However, with increasing voltage, the behavior of the molten oxide electrolyte changes, the anode yield decreases, which thus reveals the appearance of a second anode half reaction.…”

Section: Yield Of O 2 Productionmentioning

confidence: 99%

The Impact of Iron Oxide Concentration on the Performance of Molten Oxide Electrolytes for the Production of Liquid Iron Metal

Wiencke

Lavelaine

Panteix

et al. 2019

Metall Mater Trans B

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The effect of iron oxide concentration on the conductive behavior of a molten oxide electrolyte has been investigated at 1823 K using stepped linear scan voltammetry. To maximize the current flow through the electrolyte the ohmic drop in the cell was minimized by shortening the electrode distance. The acquired current was then interpreted by means of an ohmic drop correction, taking into account the conductivity of the alumina-silicate electrolyte and the geometrical form factor of the cell. Via this methodology, a mass transfer limitation in dependence of the iron oxide concentration was identified. This mass transfer limitation vanishes above 7 wt pct of iron oxide where charge transfer starts to be limited solely by electrochemical reaction kinetics. In the analyzed range of concentration, an impact of iron oxide on electronic conduction was not measurable. In addition to these findings, the faradaic yield of the anode half-reaction was determined by the life-measure of O 2 -production. Hereby, a domain of an anodic yield close to 100 pct for various iron oxide concentrations was identified. Based on these findings, suitable conditions for the electrochemical production of liquid iron were determined.

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Influence of mass transfer and electrolyte composition on anodic oxygen evolution in molten oxides

Cited by 15 publications

References 10 publications

Electrochemical behaviour of titanium-bearing slag relevant for molten oxide electrolysis

Electrochemical behaviour of titanium-bearing slag relevant for molten oxide electrolysis

Determination of the Partial Contributions to the Electrical Conductivity of TiO2-SiO2-Al2O3-MgO-CaO Slags: Role of the Experimental Processing Conditions

The Impact of Iron Oxide Concentration on the Performance of Molten Oxide Electrolytes for the Production of Liquid Iron Metal

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