System for electrocatalytic conversion of carbon oxides to multicarbon products using a stationary catholyte layer and related process

Abstract

An electroreduction system for converting carbon oxides selected from CO, CO 2 or any mixture thereof into multicarbon (C 2+ ) products. the system comprising a cathodic compartment having a reactant inlet and comprising a cathode, the cathode comprising a catalyst layer that is contactable with a catholyte solution; an anodic compartment having a product outlet to release the C 2+ products, the anodic compartment comprising an anode and being configured to accommodate a flowing anolyte solution; and a bipolar membrane being positioned between the cathodic compartment and the anodic compartment, the bipolar membrane comprising an interfacial layer defined between a cation-exchange layer and a anion-exchange layer, wherein the cathodic compartment is configured to accommodate a stationary catholyte layer between the catalyst layer of the cathode and the CEL, the stationary catholyte layer comprising the catholyte solution.

1 - 40 . (canceled) 
     
     
         41 . An electroreduction system for converting carbon oxides selected from CO, CO 2  or any mixture thereof into multicarbon (C 2 +) products, the system comprising:
 a cathodic compartment having a reactant inlet for receiving a stream of CO, CO 2  or any mixture thereof, and comprising a cathode, the cathode comprising a catalyst layer that is in contact with a catholyte solution:   an anodic compartment, the anodic compartment comprising an anode and accommodating a flowing anolyte solution;   a bipolar membrane being positioned between the cathodic compartment and the anodic compartment, the bipolar membrane comprising:
 a cation-exchange layer (CEL) in cation communication with the catholyte solution to provide protons into the catholyte solution; 
 an anion-exchange layer (AEL) in anion communication with the anolyte solution to provide hydroxide ions at a surface of the anode; and 
 an interfacial layer defined between the cation-exchange layer and the anion-exchange layer for splitting water into the protons and the hydroxide ions; 
   wherein the cathodic compartment and/or the anodic compartment have a product outlet to release the C 2+  products;   characterized in that the cathodic compartment accommodates a stationary catholyte layer between the catalyst layer of the cathode and the CEL, the stationary catholyte layer comprising the catholyte solution; in that the thickness of the stationary catholyte layer is at most 280 μm as measured by a spiral micrometer; and in that the catholyte solution is a non-buffered solution.   
     
     
         42 . The system according to  claim 41 , characterized in that the cathodic compartment further comprises a solid porous support in between the CEL and the catalyst layer, and in that the solid porous support is saturated with the catholyte solution to form the stationary catholyte layer. 
     
     
         43 . The system according to  claim 42 , characterized in that the solid porous support comprises polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polycarbonate, nylon, cellulose acetate, cellulose nitrate, polypropylene, alumina, or any combinations thereof. 
     
     
         44 . The system according to  claim 41 , characterized in that the cations in the catholyte solution are one or more selected from K + , Na + , Cs + , Rb + , NH 4+ , Mg 2+ , Ca 2+ , Al 3+ . 
     
     
         45 . The system according to  claim 41 , characterized in that the non-buffered solution is or comprises K 2 SO 4 , KCl or any other combinations of the Cl −  anions or SO 4   2−  anions with Na + , Cs + , Rb + , NH 4+ , Mg 2+ , Ca 2+ , or Al 3+  cations. 
     
     
         46 . The system according to  claim 41 , characterized in that the anolyte solution has a pH between 7 and 10. 
     
     
         47 . The system according to  claim 41 , characterized in that the anolyte solution is an acidic solution and has a pH between 1 and 4. 
     
     
         48 . The system according to  claim 41 , characterized in that the catalyst layer of the cathode comprises copper (Cu), silver (Ag), platinum (Pt), carbon (C), or any combination thereof. 
     
     
         49 . The system according to  claim 41 , characterized in that the cathode further comprises a gas diffusion layer for contacting the stream of CO, CO 2  or any mixture thereof, and the catalyst layer is deposited onto the gas diffusion layer. 
     
     
         50 . The system according to  claim 41 , characterized in that the anode comprises an anodic catalyst layer and an anodic current collector layer. 
     
     
         51 . The system according to  claim 41 , characterized in that the interfacial layer of the bipolar membrane comprises a water dissociation catalyst. 
     
     
         52 . The system according to  claim 41 , characterized in that the AEL is a membrane comprising poly (aryl piperidinium), polystyrene methyl methylimidazolium, or polystyrene tetramethyl methylimidazolium. 
     
     
         53 . The system according to  claim 41 , characterized in that the CEL comprises or consists of a sulfonated tetrafluoroethylene based fluoropolymer-copolymer. 
     
     
         54 . The system according to  claim 41 , characterized in that it further comprising a temperature controller configured to maintain an operating temperature between 20° C. and 50° C. 
     
     
         55 . A carbon oxides electroreduction process for converting CO, CO 2  or any mixture thereof into C 2+  products, the process comprising:
 supplying a catholyte solution and a stream of CO, CO 2  or any mixture thereof to a cathodic compartment comprising a catalyst layer in contact with the catholyte solution; 
 and having a product outlet to release the C 2+  products: 
 flowing an anolyte solution through an anodic compartment, the anodic compartment comprising an anode; 
 providing a bipolar membrane between the cathodic compartment and the anodic compartment, the bipolar membrane comprising:
 a cation-exchange layer (CEL) in cation communication with the catholyte solution to provide protons into the catholyte solution; 
 an anion-exchange layer (AEL) in anion communication with the anolyte solution to provide hydroxide ions into the anolyte solution; and 
 an interfacial layer defined between the cation-exchange layer and the anion-exchange layer for splitting water into the protons and the hydroxide ions; and 
 
 retaining a portion of the catholyte solution as a stationary catholyte layer between the catalyst layer of the cathode and the CEL and in contact with the CEL; wherein the thickness of the stationary catholyte layer is at most 280 μm as measured by a spiral micrometer and wherein the catholyte solution is a non-buffered solution. 
 
     
     
         56 . The process of  claim 55 , comprising maintaining an operating temperature between 20° C. and 50° C. 
     
     
         57 . The process of  claim 55 , characterized in that supplying the stream of CO, CO 2  or any mixture thereof to the cathodic compartment is performed at an inlet flowrate between 1 sccm and 15 sccm. 
     
     
         58 . The process of  claim 55 , characterized in that comprising providing the cathode with an applied current density between 100 and 400 mA·cm −2 . 
     
     
         59 . The process of  claim 55 , characterized in that comprising forming the stationary catholyte layer by providing a solid porous support between the cathode and the CEL, and saturating the solid porous support with the catholyte solution. 
     
     
         60 . The process of  claim 59 , characterized in that the saturating is performed to reach a liquid content of the stationary catholyte layer between 5 and 50 μL·cm −2 , optionally between 10 and 20 μL·cm −2  when the solid porous support is saturated with the catholyte solution; the liquid content being determined by weighting.