Methods and system for electrochemical production of formic acid from carbon dioxide

Abstract

The present disclosure provides an electrochemical system for generating formic acid from carbon dioxide. The electrochemical system comprises an electrochemical cell and a power source. The electrochemical cell comprises electrochemical compartments and several ion exchange membranes. Methods for generating formic acid from carbon dioxide is also provided.

1 . An electrochemical system for converting CO 2  to formic acid by the protonation of formate ions with hydronium ions, wherein the system comprises an electrochemical cell in electrical communication with an electrical energy source, wherein
 the electrochemical cell comprises a cathode compartment, a first central flow compartment, a second central flow compartment and an anode compartment, wherein   a first anion exchange membrane is interposed between and ionically communicating with the cathode compartment and the first central flow compartment, a second anion exchange membrane is interposed between and ionically communicating with the first central flow compartment and the second central flow compartment, and a cation exchange membrane is interposed between and ionically communicating with the second central flow compartment and the anode compartment, wherein   the electrical energy source applies a potential difference across the anode and the cathode; wherein   the first central flow compartment has a first central flow compartment inlet and a first central flow compartment outlet, and the second central flow compartment has a second central flow compartment inlet and a second central flow compartment outlet, wherein   the cathode compartment produces formate from carbon dioxide and the anion compartment produces hydronium ions from water, and wherein   the configuration of the electrochemical cell defines a fluid flow path, an ionic conduction path, or a combination thereof; and wherein   carrier media are employed to rinse ions from the first central flow compartment into the second central flow compartment, and also to efflux formic acid from the second central flow compartment.   
     
     
         2 . The electrochemical system of  claim 1 , wherein the cathode compartment comprises a cathode current collector, a gas flow channel inlet, a gas diffusion electrode (GDE) structure, and a GDE electrocatalyst layer. 
     
     
         3 . The electrochemical system of  claim 1 , wherein the anode compartment comprises an anode base current collector, an anolyte solution inlet, an anode diffusion layer, and an anode catalyst. 
     
     
         4 . The electrochemical system of  claim 1 , wherein the first central flow compartment comprises an anion exchange material. 
     
     
         5 . The electrochemical system of  claim 1 , wherein the second central flow compartment comprises a cation exchange material. 
     
     
         6 . The electrochemical system of claim of  claim 1 , wherein the electrochemical cell has a faradic efficiency of 60% or more. 
     
     
         7 . The electrochemical system of  claim 1 , wherein the electrochemical cell generates 15% or more formic acid concentration. 
     
     
         8 . The electrochemical system of  claim 1 , wherein the fluid flow path in the first central flow compartment is opposite the fluid flow path in the second central flow compartment. 
     
     
         9 . The electrochemical system of  claim 1 , wherein the fluid flow path in the first central flow compartment is parallel to the fluid flow in the second central flow compartment. 
     
     
         10 . The electrochemical system of  claim 1 , wherein the fluid flow path in the first central flow compartment is independent from the fluid flow path in the second central flow compartment. 
     
     
         11 - 12 . (canceled) 
     
     
         13 . The electrochemical system of  claim 1 , wherein the first central flow chamber contains an anion exchange material. 
     
     
         14 . A method for making formic acid, comprising:
 contacting an electrically active cathode to a CO 2  source material to convert CO 2  to HCOO − ;   separating the formed HCOO −  from the cathode;   passing the formed HCOO −  through a first anion exchange membrane along an ion conduction path;   passing the formed HCOO −  through a first central flow compartment containing an anion exchange material;   passing the formed HCOO −  through a second anion exchange membrane from the first flow compartment into a second central flow compartment along an ion conduction path;   contacting an electrically active anode to a water source to convert the water source into hydronium ions and hydroxyl ions;   separating the formed hydronium ions from the anode;   selectively passing the formed hydronium ions into the second central flow compartment through a cation exchange membrane separating the second central flow compartment from the anode compartment along an ion conduction path;   forming formic acid in the second central flow compartment with the transported HCOO— from the first central flow compartment and the hydronium ions from the anode compartment, where the HCOO −  may be protonated to form formic acid;   rinsing formic acid present in the first central flow compartment along an independent flow path with a carrier medium; and   removing the formic acid product effluent from the second central flow compartment along the fluid flow path.   
     
     
         15 . The method of  claim 14 , wherein the fluid flow path comprises passing a carrier medium from the first central flow compartment into the second central flow compartment. 
     
     
         16 . The method of  claim 14 , wherein rinsing the formed formic acid from the first central flow compartment to the second flow compartment is at a flow rate between 0.5 mL/hour and 10 mL/hour. 
     
     
         17 . (canceled) 
     
     
         18 . The method of  claim 14 , wherein the carrier medium comprises distilled water. 
     
     
         19 . The method of  claim 14 , wherein the carrier medium comprises nitrogen gas. 
     
     
         20 . The method of  claim 14 , wherein fluid flow path is oblique to the ionic conduction path. 
     
     
         21 . The method of  claim 14 , wherein the method reduces the concentration of formic acid or hydronium ions adjacent the cathode. 
     
     
         22 . The method of  claim 14 , wherein the method reduces the concentration of formate adjacent the anode. 
     
     
         23 . The method of  claim 14 , wherein the formic acid concentration is lower in the first central flow compartment as compared to the second central flow compartment.