CO2 Electrolyzer

Abstract

Various embodiments include a CO2 electrolyzer comprising: a gas space adjoining a cathode comprising a gas diffusion electrode adjoining a cathode space; an anode in an anode space; a membrane separating the cathode space from the anode space; a feed apparatus feeding reactant gas into the gas space; a mixing vessel for at least partial joint accommodation of the anolyte and the catholyte; and a connection line between the gas separating region and the gas space. The mixing vessel includes a gas separating region closed off with respect to a surrounding atmosphere. The cathode space accommodates a catholyte and the anode space accommodates an anolyte.

What is claimed is: 
     
         1 . A CO2 electrolyzer comprising:
 a gas space adjoining a cathode;   the cathode comprising a gas diffusion electrode adjoining a cathode space;   an anode in an anode space;   a membrane separating the cathode space from the anode space;   wherein the cathode space accommodates a catholyte and the anode space accommodates an anolyte;   a feed apparatus feeding reactant gas into the gas space;   a mixing vessel for at least partial joint accommodation of the anolyte and the catholyte;   wherein the mixing vessel includes a gas separating region closed off with respect to a surrounding atmosphere; and   a connection line between the gas separating region and the gas space.   
     
     
         2 . The electrolyzer as claimed in  claim 1 , wherein:
 a mixture of the catholyte and the anolyte present in the mixing vessel has a total concentration of negative charge carriers; and   the cumulative proportion of hydrogencarbonate ions, carbonate ions, and hydroxide ions is less than 20% of the total concentration of negative charge carriers.   
     
     
         3 . The electrolyzer as claimed in  claim 1 , further comprising a feed apparatus on the mixing vessel for the reactant gas;
 wherein the reactant gas is at least partially fed into the gas space via the mixing vessel.   
     
     
         4 . The CO2 electrolyzer as claimed in  claim 1 , wherein:
 a CO2-containing reactant gas is introduced into the gas space;   after flowing through the cathode space or the anode space respectively, the catholyte and the anolyte are conducted into the mixing vessel; and   a CO2-containing gas is evolved from a mixture of the liquid catholyte and the liquid anolyte and in turn is fed to the gas space as part of the reactant gas.   
     
     
         5 . The CO2 electrolyzer as claimed in  claim 1 , wherein an operating pressure prevailing in the electrolyzer is less than 5 bar. 
     
     
         6 . The CO2 electrolyzer as claimed in  claim 1 , wherein the reactant gas is conducted through the mixing vessel and introduced together with the CO2-containing gas evolved there into the gas space.