Carbon dioxide electrolytic device and method of electrolyzing carbon dioxide

Abstract

A carbon dioxide electrolytic device of an embodiment includes: an electrolysis cell including a cathode to reduce carbon dioxide, an anode to oxidize water or hydroxide ion and having a base containing titanium, a cathode flow path to supply carbon dioxide to the cathode, an anode flow path to supply an electrolytic solution containing water to the anode, and a separator to separate the anode and the cathode; a gas supply unit to supply carbon dioxide to the cathode flow path; at least either of a humidifier to humidify carbon dioxide supplied to the cathode flow path by using a humidification water, and a liquid pouring part to add the humidification water to the carbon dioxide; and an electrolytic solution supply unit to supply the electrolytic solution to the anode flow path. At least one of the electrolytic solution, the humidification water, and the supplied gas contains an oxidant.

What is claimed is: 
     
         1 . A carbon dioxide electrolytic device, comprising:
 an electrolysis cell including a cathode configured to reduce carbon dioxide to produce a carbon compound, an anode configured to oxidize water or hydroxide ion to produce oxygen and having a base containing titanium, a cathode flow path configured to supply carbon dioxide to the cathode, an anode flow path configured to supply an electrolytic solution containing water to the anode, and a separator configured to separate the anode and the cathode;   a gas supply unit configured to supply carbon dioxide to the cathode flow path;   at least one of a humidifier configured to humidify carbon dioxide supplied to the cathode flow path by using a humidification water, and a liquid pouring part configured to add the humidification water to the carbon dioxide; and   an electrolytic solution supply unit configured to supply the electrolytic solution to the anode flow path, wherein
 at least one of the electrolytic solution and the humidification water contains an oxidant; and/or 
 the carbon dioxide gas supplied to the cathode flow path contains at least one selected from a group consisting of nitrogen dioxide, nitrogen monoxide, and ozone. 
   
     
     
         2 . The device according to  claim 1 , wherein
 the oxidant is at least one selected from a group consisting of an oxidizing acid and hydrogen peroxide.   
     
     
         3 . The device according to  claim 2 , wherein
 the oxidizing acid includes at least one selected from a group consisting of nitric acid, perchloric acid, chloric acid, chlorous acid, hypochlorous acid, chromic acid, dichromic acid, permanganic acid, arsenic acid, selenic acid, bromic acid, and iodic acid.   
     
     
         4 . The device according to  claim 1 , wherein
 a concentration of the oxidant in at least one of the electrolytic solution and the humidification water is 0.1 mM or more and 100 mM or less.   
     
     
         5 . The device according to  claim 1 , wherein
 a concentration of at least one selected from the group consisting of nitrogen dioxide, nitrogen monoxide, and ozone in the carbon dioxide gas is 10 ppb or more and 1000 ppm or less.   
     
     
         6 . The device according to  claim 1 , wherein
 the electrolytic solution has a pH of 6 or more and 10 or less.   
     
     
         7 . The device according to  claim 1 , further comprising a measurement part configured to measure a concentration of the oxidant in at least one of the electrolytic solution and the humidification water. 
     
     
         8 . The device according to  claim 1 , wherein
 the separator includes a porous membrane.   
     
     
         9 . A method of electrolyzing carbon dioxide, comprising:
 supplying humidified carbon dioxide to a cathode of an electrolysis cell via a cathode flow path, and supplying an electrolytic solution to an anode having a base containing titanium of the electrolysis cell via an anode flow path; and   supplying a current to the cathode and the anode, and reducing carbon dioxide to produce a carbon compound, wherein
 an oxidant is added to at least one of the electrolytic solution and a humidification water used for humidifying carbon dioxide; and/or 
 at least one selected from a group consisting of nitrogen dioxide, nitrogen monoxide, and ozone is added to the carbon dioxide gas supplied to the cathode flow path. 
   
     
     
         10 . The method according to  claim 9 , wherein
 the oxidant is at least one selected from a group consisting of an oxidizing acid and hydrogen peroxide.   
     
     
         11 . The method according to  claim 10 , wherein
 the oxidizing acid includes at least one selected from a group consisting of nitric acid, perchloric acid, chloric acid, chlorous acid, hypochlorous acid, chromic acid, dichromic acid, permanganic acid, arsenic acid, selenic acid, bromic acid, and iodic acid.   
     
     
         12 . The method according to  claim 9 , wherein
 to at least either of the electrolytic solution and the humidification water, the oxidant is added at a concentration of 0.1 mM or more and 100 mM or less.   
     
     
         13 . The method according to  claim 9 , wherein
 to the carbon dioxide gas, at least one selected from the group consisting of nitrogen dioxide, nitrogen monoxide, and ozone is added at a concentration of 10 ppb or more and 1000 ppm or less.   
     
     
         14 . The method according to  claim 9 , wherein
 the electrolytic solution has a pH of 6 or more and 10 or less.