CO2 gas decomposition to carbon by electro-reduction in molten salts

Otake, Koya; Kinoshita, Hiroshi; Kikuchi, Tatsuya; Suzuki, Ryosuke O.

doi:10.1016/j.electacta.2013.02.076

Cited by 79 publications

(100 citation statements)

References 17 publications

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“…6b, the current intensity (I) exhibits a good linear relationship with the transition time (¸), which verifies Sand's law [Eq. (8)] and suggests that the electrochemical reduction of carbonate ions is a diffusioncontrolled process: For an irreversible process, the relationship between potential and time is shown in Eq. (9):…”

Section: Chronopotentiometry Studymentioning

confidence: 99%

See 1 more Smart Citation

Electrochemical Behavior of Carbonate Ion in the LiF^|^ndash;NaF^|^ndash;Li2CO3 System

Shi

Gao

et al. 2014

Electrochemistry

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The electrochemical behavior of carbonate ion at a Ni electrode in LiF-NaF-Li 2 CO 3 molten salt was investigated using cyclic voltammetry, square wave voltammetry, and chronopotentiometry. The results show that the electrochemical reduction of carbonate ion to carbon is a simple four-electron transfer that occurs in a one-step process. The reduction of carbonate ion at a Ni-wire working electrode is an irreversible process with diffusioncontrolled mass transfer. The diffusion coefficient of carbonate ion at 973, 993, 1023, 1043, and 1063 K is 4.46 × 10 . The X-ray diffraction results show that hexagonally structured graphitized carbon can be obtained by potentiostatic electrolysis. Scanning electron microscopy images show that the deposits exhibit a spherical morphology.

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Section: Chronopotentiometry Studymentioning

confidence: 99%

“…9,10 Some researchers have investigated the conversion of CO 2 into carbon or carbon monoxide by electrolysis in a molten salt. 8,[10][11][12][13] Carbon deposition has typically been achieved through the formation of carbon powders or carbon film.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Behavior of Carbonate Ion in the LiF^|^ndash;NaF^|^ndash;Li2CO3 System

Shi

Gao

et al. 2014

Electrochemistry

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“…[4][5][6][7][8][9] As a new method to reduce metallic oxides such as titanium, vanadium, tantalum and nickel to their metallic state, an OS process consisting of electro-reduction of CaO and calciothermic reduction in a CaCl 2 bath has been studied. 10) The energy inputs in the CO 2 gas decomposition reaction in this method are supplied by electro-reduction of CaO and the calciothermic reduction.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, as the electric energy used in this process is direct current (DC), the process is effective for the direct use of renewable energy, in that DC generation is the mainstream. In a study using CaCl 2 -CaO molten salt and 9.7% CO 2 -Ar mixed gas (CO 2 gas and Ar gas were blown at 5.0 × 10 − 8 m 3 /s and 4.7 × 10 − 7 m 3 /s, respectively), K. Otake et al 6) reported that the current efficiency was 78.5% and the collected carbon yield was 36%. Although the CO 2 decomposition amount is low because of the small scale of the experiments at the present stage (for example, the CO 2 decomposition amount is about 1.5 parts per billion with a large blast furnace), this is considered to be one potential process for the future.…”

Section: Introductionmentioning

confidence: 99%

Influence of Gas Injection Pipe on CO2 Decomposition by CaCl2–CaO Molten Salt and ZrO2 Solid Electrolysis

Ozawa¹,

Matsuno²,

Fujibayashi³

et al. 2016

ISIJ Int.

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The electrochemical decomposition of carbon dioxide to form carbon and oxygen gas in CaCl 2 -CaO molten salt was studied. A water model experiment was carried out to study the influence of the tip shape of the pipe, the pipe diameter and the wettability of the gas injection pipe on the bubble shape in the molten salt. Bubbles were formed with both a horizontal tip and an oblique tip when the wettability of the gas injection pipe was good. The specific surface area of the bubbles when using the oblique tip was smaller than when using the horizontal tip. On the other hand, slug flows appeared when wettability was poor. In a hot model experiment, the current density was measured, and it was found that the CO 2 gas concentration decreased. Precipitated carbon was detected from the sample after the experiment. With the same pipe, the decrease of the CO 2 gas concentration when using the oblique tip was more remarkable than when using the horizontal tip. It is likely that the form of the CO 2 gas in the molten salt was bubble-shaped.

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“…Metallic titanium [13][14][15], niobium [16], nickel [17], and other alloys and intermetallic compounds [18,19] can be formed via the OS process. In addition, the electrochemical decomposition of carbon dioxide gas by an advanced OS process using a solid electrolyte anode has been reported [20,21]. Fray, Farthing, and Chen investigated the cathodic deoxidation of metal oxides in calcium chloride and calcium oxide mixture molten salts and reported the production of metallic titanium [22][23][24][25][26], iron [27], chromium [28], zirconium [29], hafnium [30], tantalum [31], and other alloys [32][33][34] through the FFC (Fray, Farthing, and Chen) Cambridge process.…”

Section: Introductionmentioning

confidence: 99%

Rapid reduction of titanium dioxide nano-particles by reduction with a calcium reductant

Kikuchi

Yoshida

Matsuura

et al. 2014

Journal of Physics and Chemistry of Solids

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Micro-, submicron-, and nano-scale titanium dioxide particles were reduced by reduction with a metallic calcium reductant in calcium chloride molten salt at 1173 K, and the reduction mechanism of the oxides by the calcium reductant was explored. These oxide particles, metallic calcium as a reducing agent, and calcium chloride as a molten salt were placed in a titanium crucible and heated under an argon atmosphere. Titanium dioxide was reduced to metallic titanium through a calcium titanate and lower titanium oxide, and the materials were sintered together to form a micro-porous titanium structure in molten salt at high temperature. The reduction rate of titanium dioxide was observed to increase with decreasing particle size; accordingly, the residual oxygen content in the reduced titanium decreases. The obtained micro-porous titanium appeared dark gray in color because of its low surface reflection. Micro-porous metallic titanium with a low oxygen content (0.42 wt%) and a large surface area (1.794 m 2 g -1 ) can be successfully obtained by reduction under optimal conditions. Key words: Titanium, Calcium, Calciothermic reduction, Nano-particles, Electrolytic capacitor IntroductionMetallic calcium can easily reduce a large number of metal oxides directly to metals because calcium has a strong reducing ability. The reduction of metal oxides with a calcium reductant in calcium chloride molten salt at high temperature, well known as the calciothermic reaction, has long been widely investigated by many researchers. During oxide reduction, calcium chloride molten salt acts as a suitable solvent and has a high solubility for calcium and calcium oxide as a byproduct formed by reduction. [11] are formed via reduction of these oxides with a calcium reductant in calcium chloride molten salt. The residual oxygen in the reduced metal decreases continuously by deoxidation with a calcium reductant [4]. Pure metals, alloys, and intermetallic compounds with a lower residual oxygen content can be successfully fabricated by a one-step reduction technique. Reduction with a calcium reductant is a simpler technique for the production of these metals without complicated processes such as the Kroll process, although reduction is a batch-type production method.In recent years, a method for the successive reduction of metal oxides was developed by electrolysis in calcium chloride and calcium oxide mixture molten salts. Ono and Suzuki reported that calcium oxide in molten calcium chloride becomes the reductant source for the reduction of metal oxides during constant-voltage electrolysis [12]. For example, metallic calcium formed electrochemically at a cathode reacts with metal oxides, and reduced metals with a low residual oxygen content can be formed (OS (Ono and Suzuki) Kyoto process). Metallic titanium [13][14][15], niobium [16], nickel [17], and other alloys and intermetallic compounds [18,19] can be formed via the OS process. In addition, the electrochemical decomposition of carbon dioxide gas by an advanced OS process using ...

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CO2 gas decomposition to carbon by electro-reduction in molten salts

Cited by 79 publications

References 17 publications

Electrochemical Behavior of Carbonate Ion in the LiF^|^ndash;NaF^|^ndash;Li2CO3 System

Electrochemical Behavior of Carbonate Ion in the LiF^|^ndash;NaF^|^ndash;Li2CO3 System

Influence of Gas Injection Pipe on CO<sub>2</sub> Decomposition by CaCl<sub>2</sub>–CaO Molten Salt and ZrO<sub>2</sub> Solid Electrolysis

Rapid reduction of titanium dioxide nano-particles by reduction with a calcium reductant

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