Carbon dioxide enrichment device

Abstract

A carbon dioxide enrichment device, comprising: first and second gas diffusion electrodes; and an electrolytic solution existing between them to be in contact with them, wherein the electrolytic solution contains solvent and solute dissolved in it, and the solute is dissolved to form a dissolved inorganic carbon containing carbonic acid, hydrogen carbonate ions, or carbonic acid ions; oxygen is consumed by an oxygen reduction reaction on the first gas diffusion electrode, whereby a dissolved inorganic carbon is formed by a dissolution and ionization reaction of carbon dioxide in the solvent; the dissolved inorganic carbon derived from the solute or the dissolved inorganic carbon is transported to the second gas diffusion electrode; and oxygen is formed from the solvent in the vicinity of the second gas diffusion electrode by an oxidation reaction of the solvent on it, and carbon dioxide is formed from the dissolved inorganic carbon.

1 . A carbon dioxide enrichment device, comprising:
 a first gas diffusion electrode;   a second gas diffusion electrode separated from the first gas diffusion electrode; and   an electrolytic solution existing between the first gas diffusion electrode and the second gas diffusion electrode to be in contact with the first gas diffusion electrode and the second gas diffusion electrode,   wherein the electrolytic solution contains a solvent and a solute dissolved in the solvent, and the solute is dissolved in the solvent to form a dissolved inorganic carbon containing at least one of carbonic acid, hydrogen carbonate ions, and carbonic acid ions; oxygen is consumed by an oxygen reduction reaction on the first gas diffusion electrode, whereby a dissolved inorganic carbon is formed by a dissolution and ionization reaction of carbon dioxide in the solvent; the dissolved inorganic carbon derived from the solute or the dissolved inorganic carbon formed on the first gas diffusion electrode is transported to the second gas diffusion electrode; and oxygen is formed from the solvent in the vicinity of the second gas diffusion electrode by an oxidation reaction of the solvent on the second gas diffusion electrode, and carbon dioxide is formed from the dissolved inorganic carbon.   
     
     
         2 . The carbon dioxide enrichment device according to  claim 1 , wherein a total inorganic carbon concentration in the electrolytic solution, calculated by the following [Equation 1], is 100 μmol or more:
   (Total inorganic carbon concentration)=[H 2 CO 3 ]+[HCO 3   − ]+[CO 3   2− ].  [Equation 2]
 
 
     
     
         3 . The carbon dioxide enrichment device according to  claim 1 , wherein pH of the electrolytic solution is in the range of from 5 to 14. 
     
     
         4 . The carbon dioxide enrichment device according to  claim 1 , wherein a molar ratio of carbon dioxide and oxygen to be emitted from the second gas diffusion electrode is in the range of from 1:0.1 to 1:10. 
     
     
         5 . The carbon dioxide enrichment device according to  claim 1 , wherein the first gas diffusion electrode and the second gas diffusion electrode comprise a porous conductor and an electrode catalyst. 
     
     
         6 . The carbon dioxide enrichment device according to  claim 5 , wherein the electrode catalyst contains a metal complex or a catalytic component of the metal complex, the metal complex containing any one of a polymer of one or more monomers selected from the group consisting of diaminopyridine, triaminopyridine, tetraminopyridine, a diaminopyridine derivative, a triaminopyridine derivative, and a tetraminopyridine derivative; or a modified product of the polymer; or a catalytic metal; and the electrode catalyst satisfying at least one of the following (i) and (ii):
 (i) the content of metal coordinated to a nitrogen atom, analyzed by X-ray photoelectron spectroscopy, is 0.4 mol % or more, and   (ii) the existence of metal coordinated to a nitrogen atom is recognized by X-ray photoelectron spectroscopy, and the content of the nitrogen atom is 6.0 mol % or more.   
     
     
         7 . The carbon dioxide enrichment device according to  claim 6 , wherein the electrode catalyst contains a polymer of one or more monomers selected from the group consisting of diaminopyridine, triaminopyridine, and tetraminopyridine; or a fired metal complex obtained by firing a polymer metal complex composed of a catalytic metal; or a catalyst component of the fired metal complex. 
     
     
         8 . The carbon dioxide enrichment device according to  claim 5 , wherein a specific surface area of the porous conductor is 1 m 2 /g or more, in the BET adsorption measurement. 
     
     
         9 . The carbon dioxide enrichment device according to  claim 1 , wherein the electrolytic solution is a polymer gel electrolyte. 
     
     
         10 . The carbon dioxide enrichment device according to  claim 1 , wherein the electrolytic solution contains a carbonic anhydrase catalyst facilitating a reaction of the following [Chemical Formula 1]:
   CO 2 +H 2 O→HCO 3   − +H + .  [Chemical Formula 1]