CO2 gas is decomposed to CO and C by the molten salt electrolysis using CaCl2-CaO and solid state electrolyte, zirconia, as the anode. Partially CO2 gas dissolves to form CO3 2and it is electrochemically decomposed to carbon. The other portion of CO2 gas bubbles reacts with metallic Ca electrochemically deposited near the cathode, and forms C or CO gas. By increasing the flow rate of CO2 gas to the reactor, a high concentration of CO gas is generated. By increasing the concentration of CO2 gas in the initial gas, a large amount of CO gas was produced in the exhaust gas, and its rate approached to 3.32×10-8 m 3 /s in our experimental setup. These experimental evidences reflect the electrochemical decomposition of CO3 2in the molten salt.

10Carbonate ions in LiCl-Li 2 O salt are a source of carbon contamination in the electrolytic 11 refining of metal oxides, and their concentration is also essential information for 12 understanding the CO 2 decomposition process. In this study, the solubility of gaseous 13 CO 2 in molten LiCl-Li 2 O was studied, with the goal of developing processes to 14 decompose the oxides effectively. Ar-CO 2 gas mixtures were dissolved in molten salts 15 containing various amounts of Li 2 O, and the solubility of the CO 2 gas was calculated by 16 measuring the mass difference between the molten salts before and after the CO 2 17 dissolution. The molar amount of dissolved CO 2 gas was almost as large as the molar

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

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.