Electrolytic System And Reduction Method For Electrochemical Carbon Dioxide Utilization, Alkali Carbonate Preparation And Alkali Hydrogen Carbonate Preparation

Abstract

The present disclosure relates to electrolysis. The teachings thereof may be embodied in a reduction process and/or an electrolysis system for electrochemical carbon dioxide utilization wherein carbon dioxide is introduced into an electrolysis cell and reduced at a cathode. For example, an electrolysis system for carbon dioxide utilization may comprise: an electrolyzer including an anode in an anode space and a cathode in a cathode space. The cathode space has an entrance for carbon dioxide. The cathode space comprises a catholyte including alkali metal cations. The anode space has an entrance for an anolyte. The anode space comprises an anolyte comprising chlorine anions.

What is claimed is: 
     
         1 . An electrolysis system for carbon dioxide utilization, the system comprising:
 an electrolyzer including an anode in an anode space and a cathode in a cathode space;   the cathode space has an entrance for carbon dioxide;   the cathode space comprises a catholyte including alkali metal cations;   the anode space has an entrance for an anolyte;   the anode space comprises an anolyte comprising chlorine anions.   
     
     
         2 . The electrolysis system as claimed in  claim 1 , further comprising a deposition tank configured for crystallization of an alkali metal hydrogencarbonate and/or alkali metal carbonate out of the catholyte;
 wherein the deposition tank includes a product outlet.   
     
     
         3 . The electrolysis system as claimed in  claim 2 , further comprising a cooling apparatus for the deposition tank. 
     
     
         4 . The electrolysis system as claimed in  claim 2 , further comprising a reservoir connected to the cathode space or the deposition tank to buffer the catholyte. 
     
     
         5 . The electrolysis system as claimed in  claim 1 , wherein the catholyte comprises a solvent. 
     
     
         6 . The electrolysis system as claimed in  claim 1 , wherein the anolyte includes at least one water-soluble alkali metal salt. 
     
     
         7 . The electrolysis system as claimed in  claim 1 , further comprising the anode space connected to a gas separation unit for separation of chlorine gas from the anolyte. 
     
     
         8 . The electrolysis system as claimed in  claim 1 , further comprising a cation-conducting membrane separating the anode space and cathode space from one another. 
     
     
         9 . A reduction process for carbon dioxide utilization, the process comprising:
 introducing a catholyte and carbon dioxide into a cathode space with a cathode;   reducing carbon dioxide at the cathode;   introducing an anolyte including chloride anions into an anode space and brought into contact with an anode;   wherein the anolyte includes alkali metal cations that migrate into the catholyte;   oxidizing chloride anions at the anode to chlorine;   separating chlorine from the anolyte as chlorine gas using a gas separation unit; and   introducing at least a portion of the catholyte volume into a deposition tank, where an alkali metal hydrogencarbonate and/or alkali metal carbonate crystallizes out.   
     
     
         10 . The reduction process as claimed in  claim 9 , further including reducing, at the cathode, carbon dioxide (CO 2 ) to carbon monoxide (CO), ethylene (C 2 H 4 ), methane (CH 4 ), ethanol (C 2 H 5 OH), and/or monoethylene glycol (OHC 2 H 4 OH). 
     
     
         11 . The reduction process as claimed in  claim 10 , further comprising converting the hydroxide ions (OH − ) formed in the carbon dioxide reduction to hydrogencarbonate ions (HCO 3   − ) with carbon dioxide (CO 2 ) present in excess. 
     
     
         12 . The reduction process as claimed in  claim 9 , further including introducing at least a portion of the catholyte into a deposition tank, where it is cooled down by at least 15 kelvin. 
     
     
         13 . The reduction process as claimed in  claim 9 , further comprising introducing at least a portion of the catholyte volume into a deposition tank, where the pH thereof is lowered from above 8 to a pH of 6 or less by blowing in carbon dioxide (CO 2 ). 
     
     
         14 . The reduction process as claimed in  claim 9 , further comprising introducing at least a portion of the catholyte volume into a deposition tank, where an alkali metal hydrogencarbonate is crystallized and is subsequently converted to an alkali metal carbonate by heating.