Carbon dioxide electrolytic device

Abstract

A carbon dioxide electrolytic device of an embodiment includes: an anode part including an anode which oxidizes water or hydroxide ions to produce oxygen; a cathode part including a cathode which reduces carbon dioxide to produce a carbon compound, a cathode solution flow path which supplies a cathode solution to the cathode, and a gas flow path which supplies carbon dioxide to the cathode; a separator which separates the anode part and the cathode part; and a differential pressure control unit which controls a differential pressure between a pressure of the cathode solution and a pressure of the carbon dioxide so as to adjust a production amount of the carbon dioxide produced by a reduction reaction in the cathode part.

What is claimed is: 
     
         1 . A carbon dioxide electrolytic device comprising:
 a cathode part including a cathode to reduce carbon dioxide and thus produce a carbon compound, a cathode solution flow path to supply a cathode solution to the cathode, and a gas flow path to supply carbon dioxide to the cathode;   an anode part including an anode to oxidize water or hydroxide ions and thus produce oxygen and an anode solution flow path to supply an anode solution to the anode;   a separator to separate the anode part and the cathode part;   a power supply to pass an electric current between the anode and the cathode;   a first pressure control unit to control a pressure of the cathode solution flowing in the cathode solution flow path;   a second pressure control unit to control a pressure of the carbon dioxide flowing in the gas flow path;   a detection unit to detect a production amount of the carbon compound produced by a reduction reaction in the cathode part; and   a differential pressure control unit to control a differential pressure between a pressure of the cathode solution and a pressure of the carbon dioxide so as to adjust the production amount of the carbon compound detected in the detection unit.   
     
     
         2 . The device according to  claim 1 , wherein the differential pressure control unit controls the first and second pressure control units so that an absolute value of the differential pressure between the pressure of the cathode solution and the pressure of the carbon dioxide is 0.1 kPa or more to 100 kPa or less. 
     
     
         3 . The device according to  claim 1 , wherein the differential pressure control unit controls the first and second pressure control units so that the pressure of the carbon dioxide is larger than the pressure of the cathode solution. 
     
     
         4 . The device according to  claim 1 ,
 wherein the anode has a first surface in contact with the separator and a second surface facing the anode solution flow path so that the anode solution is in contact with the anode, and   wherein the cathode has a first surface facing the cathode solution flow path and a second surface facing the gas flow path, and the cathode solution flow path is disposed between the separator and the cathode so that the cathode solution is in contact with the separator and the cathode.   
     
     
         5 . The device according to  claim 4 , wherein the cathode has a gas diffusion layer disposed on the second surface side and a catalyst layer disposed on the first surface side and constituted of a cathode catalyst provided on the gas diffusion layer. 
     
     
         6 . The device according to  claim 5 , wherein the cathode catalyst contains at least one metal selected from the group consisting of Au, Ag, Cu, Pt, Pd, Ni, Co, Fe, Mn, Ti, Cd, Zn, In, Ga, Pb, and Sn, and has at least one selected from the group consisting of nanoparticles of the metal, a nanostructure of the metal, nanowires of the metal, and a composite body in which the nanoparticles are supported by carbon particles, carbon nanotubes, or graphene. 
     
     
         7 . The device according to  claim 4 ,
 wherein the anode includes a base material having at least one selected from the group consisting of a mesh material, a punching material, a porous body, and a metal fiber sintered body, and   wherein the anode has the base material constituted of an anode catalyst or a catalyst layer constituted of an anode catalyst provided on a surface of the base material.   
     
     
         8 . The device according to  claim 7 , wherein the base material is constituted of a metal material containing at least one selected from the group consisting of Ti, Ni, and Fe, and the anode catalyst is constituted of a metal material containing at least one metal selected from the group consisting of Ni, Fe, Co, Mn, La, Ru, Li, Ir, In, Sn, and Ti, or an oxide material containing the metal. 
     
     
         9 . The device according to  claim 1 , wherein the anode solution and the cathode solution contain at least one ion selected from the group consisting of a hydroxide ion, a hydrogen ion, a potassium ion, a sodium ion, a lithium ion, a chloride ion, a bromide ion, an iodide ion, a nitrate ion, a sulfate ion, a phosphate ion, a borate ion, and a hydrogen carbon ion. 
     
     
         10 . The device according to  claim 1 , wherein the carbon compound to be produced by a reduction reaction of the carbon dioxide contains at least one selected from the group consisting of carbon monoxide, methane, ethane, ethylene, methanol, ethanol, and ethylene glycol.