Method and Device for the Electrochemical Utilization of Carbon Dioxide

Abstract

Various embodiments may include a method comprising: reducing carbon dioxide to a product gas comprising carbon monoxide in a electrolysis cell; separating the product gas from the catholyte in a first separation apparatus; separating off excess water in the catholyte enriched with water from the anolyte during the reduction of carbon dioxide with a stripping gas in a second separation apparatus; separating the water from the stripping gas in a third separation apparatus; and recycling the water from the third separation apparatus into the anode space.

What is claimed is: 
     
         1 . A method of electrochemical utilization of carbon dioxide, the method comprising:
 providing a first aqueous electrolyte as catholyte into a cathode space of an electrolysis cell;   providing a second aqueous electrolyte as anolyte into an anode space of the electrolysis cell, wherein the electrolysis cell comprises a membrane separating the anode space from a cathode space;   reducing carbon dioxide to a product gas comprising carbon monoxide in the electrolysis cell;   separating the product gas from the catholyte in a first separation apparatus;   separating off excess water in the catholyte enriched with water from the anolyte during the reduction of carbon dioxide with a stripping gas in a second separation apparatus;   separating the water from the stripping gas in a third separation apparatus; and   recycling the water from the third separation apparatus into the anode space.   
     
     
         2 . The method as claimed in  claim 1 , wherein the stripping gas comprises carbon dioxide and/or the product gas from the electrolysis cell. 
     
     
         3 . The method as claimed in  claim 2 , further comprising increasing the volume flow rate of the stripping gas with a fan. 
     
     
         4 . The method as claimed in  claim 2 , further comprising at least partially recycling the stripping gas into the electrolysis cell as reactant gas after the water has been separated off. 
     
     
         5 . The method as claimed in  claim 1 , further comprising heating the stripping gas prior to entry into the second separation apparatus. 
     
     
         6 . The method as claimed in  claim 1 , further comprising recycling the catholyte separated from excess water from the third separation apparatus into the cathode space. 
     
     
         7 . The method as claimed in  claim 1 , wherein a fraction not exceeding one eighth of the excess water is separated from the product gas by a condenser downstream of the first separation apparatus. 
     
     
         8 . An electrolysis apparatus for reducing carbon dioxide to carbon monoxide, the apparatus comprising:
 an electrolysis cell comprising a membrane separating an anode space from a cathode space;   a first conduit for delivering a first electrolyte as catholyte into the cathode space;   a second conduit for delivering a second electrolyte as anolyte into the anode space;   a first separation apparatus for separating a product gas comprising carbon monoxide from the catholyte;   a second separation apparatus for separating off excess water in the catholyte by means of a stripping gas;   a third separation apparatus for separating water from the stripping gas; and   a third conduit connecting the third separation apparatus to the anode space of the electrolysis cell for recycling the water into the anode space.   
     
     
         9 . The electrolysis apparatus as claimed in  claim 8 , wherein the second separation apparatus comprises at least one of: a pervaporation unit, a falling-film evaporator, or a bubble column. 
     
     
         10 . The electrolysis apparatus as claimed in  claim 8 , wherein the membrane comprises an anode. 
     
     
         11 . The electrolysis apparatus as claimed in  claim 8 , further comprising a fan disposed in the conduits that guide stripping gas to increase the volume flow rate of the stripping gas. 
     
     
         12 . The electrolysis apparatus as claimed in  claim 8 , wherein the first separation apparatus is integrated into the second separation apparatus.