Electrochemical Production of Water Using Mixed Ionically and Electronically Conductive Membranes

Abstract

Mixed ionically and electronically conductive membranes may be employed in electrochemical systems that are capable of producing water from air or molecular oxygen with high energy efficiency. The systems may comprise at least one electrochemical cell comprising: a first electrode and a second electrode, optionally in electrical communication via an external circuit; a mixed ionically and electronically conductive membrane interposed between and in contact with the first electrode and the second electrode; a hydrogen-containing gas supply in fluid communication with one of the first electrode and the second electrode; a molecular oxygen-containing gas supply in fluid communication with the other of the first electrode and the second electrode; and a first gas outlet extending from the first electrode and a second gas outlet extending from the second electrode.

What is claimed is the following: 
     
         1 . An electrochemical water generation system, comprising:
 at least one electrochemical cell comprising:
 a first electrode and a second electrode, optionally in electrical communication via an external circuit; 
 a mixed ionically and electronically conductive membrane interposed between and in contact with the first electrode and the second electrode; 
 a hydrogen-containing gas supply in fluid communication with one of the first electrode and the second electrode; 
 a molecular oxygen-containing gas supply in fluid communication with the other of the first electrode and the second electrode; and 
 a first gas outlet extending from the first electrode and a second gas outlet extending from the second electrode. 
   
     
     
         2 . The electrochemical water generation system of  claim 1 , further comprising:
 a heat exchanger in thermal communication with at least one of the first gas outlet and the second gas outlet.   
     
     
         3 . The electrochemical water generation system of  claim 2 , wherein the heat exchanger is configured to supply waste heat extracted from at least one of the first gas outlet and the second gas outlet to the mixed ionically and electronically conductive membrane. 
     
     
         4 . The electrochemical water generation system of  claim 2 , wherein the first electrode is a cathode and the molecular oxygen-containing gas supply is in fluid communication with the cathode, the second electrode is an anode and the hydrogen-containing gas supply is in fluid communication with the anode, and the mixed ionically and electronically conductive membrane comprises an oxygen ion-conductive membrane. 
     
     
         5 . The electrochemical water generation system of  claim 4 , wherein the oxygen ion-conductive membrane comprises at least one material selected from the group consisting of a defect ABO 3-d  perovskite (0,d<1), doped δ-Bi 2 O 3 , and doped, mixed-phase cerium oxide;
 wherein A is selected from the group consisting of Ba, Fe, La, Ce, and Sr, and B is selected from the group consisting of Zr, Cu, Fe and Co. 
 
     
     
         6 . The electrochemical water generation system of  claim 4 , wherein the heat exchanger is in thermal communication with the second gas outlet, and the second gas outlet is configured to withdraw steam from the second electrode. 
     
     
         7 . The electrochemical water generation system of  claim 2 , wherein the first electrode is a cathode and the molecular oxygen-containing gas supply is in fluid communication with the cathode, the second electrode is an anode and the hydrogen-containing gas supply is in fluid communication with the anode, and the mixed ionically and electronically conductive membrane comprises a proton-conductive membrane. 
     
     
         8 . The electrochemical water generation system of  claim 7 , wherein the heat exchanger is in thermal communication with the first gas outlet, and the first gas outlet is configured to withdraw steam from the first electrode. 
     
     
         9 . The electrochemical water generation system of  claim 1 , wherein the molecular oxygen-containing gas supply is configured to supply air or oxygen gas to the first electrode or the second electrode. 
     
     
         10 . The electrochemical water generation system of  claim 1 , wherein the hydrogen-containing gas supply is configured to supply at least one of hydrogen gas, a hydrocarbon gas, or ammonia gas to the first electrode or the second electrode. 
     
     
         11 . The electrochemical water generation system of  claim 1 , wherein the mixed ionically and electronically conductive membrane comprises a single-phase material. 
     
     
         12 . An electrochemical water generation system, comprising:
 at least one electrochemical cell comprising:
 a cathode and an anode, optionally in electrical communication via an external circuit; 
 a mixed ionically and electronically conductive membrane interposed between and in contact with the cathode and the anode, the mixed ionically and electronically conductive membrane comprising an oxygen ion-conductive material; 
 a hydrogen-containing gas supply in fluid communication with the anode; 
 a molecular oxygen-containing gas supply in fluid communication with the cathode; 
 a gas outlet extending from the anode; and 
 a heat exchanger in thermal communication with the gas outlet. 
   
     
     
         13 . The electrochemical water generation system of  claim 12 , wherein the heat exchanger is configured to supply waste heat extracted from the gas outlet to the mixed ionically and electronically conductive membrane. 
     
     
         14 . The electrochemical water generation system of  claim 12 , wherein the oxygen ion-conductive membrane comprises at least one material selected from the group consisting of a defect ABO 3-d  perovskite (0,d<1), doped δ-Bi 2 O 3 , and doped, mixed-phase cerium oxide;
 wherein A is selected from the group consisting of Ba, Fe, La, Ce, and Sr, and B is selected from the group consisting of Zr, Cu, Fe and Co. 
 
     
     
         15 . A method for generating water, comprising:
 supplying a molecular oxygen-containing gas to a first electrode of an electrochemical cell and a hydrogen-containing gas to a second electrode of an electrochemical cell;
 wherein a mixed ionically and electronically conductive membrane is interposed between and in contact with the first electrode and the second electrode; and 
 wherein the first electrode and the second electrode are optionally in electrical communication via an external circuit; 
   heating the mixed ionically and electronically conductive membrane to a temperature at or above that needed to maintain ionic mobility in the mixed ionically and electronically conductive membrane at or above a predetermined level;   generating an ionic species from the molecular oxygen-containing gas or the hydrogen-containing gas in one of the first electrode or the second electrode;   migrating the ionic species across the mixed ionically and electronically conductive membrane to the other of the first electrode or the second electrode;   after migrating across the mixed ionically and electronically conductive membrane, reacting the ionic species in one of the first electrode or the second electrode to form water in the form of steam; and   withdrawing the steam from one of the first electrode or the second electrode.   
     
     
         16 . The method of  claim 15 , further comprising:
 interacting the steam with a heat exchanger in thermal communication with a gas outlet containing the steam to withdraw waste heat; and   supplying the waste heat to the mixed ionically and electronically conductive membrane.   
     
     
         17 . The method of  claim 15 , wherein the first electrode is a cathode and the molecular oxygen-containing gas supply is in fluid communication with the cathode, the second electrode is an anode and the hydrogen-containing gas supply is in fluid communication with the anode, and the mixed ionically and electronically conductive membrane comprises an oxygen ion-conductive membrane. 
     
     
         18 . The method of  claim 17 , wherein the oxygen ion-conductive membrane comprises at least one material selected from the group consisting of a defect ABO 3-d  perovskite (0,d<1), doped δ-Bi 2 O 3 , and doped, mixed-phase cerium oxide;
 wherein A is selected from the group consisting of Ba, Fe, La, Ce, and Sr, and B is selected from the group consisting of Zr, Cu, Fe and Co. 
 
     
     
         19 . The method of  claim 15 , wherein the first electrode is a cathode and the molecular oxygen-containing gas supply is in fluid communication with the cathode, the second electrode is an anode and the hydrogen-containing gas supply is in fluid communication with the anode, and the mixed ionically and electronically conductive membrane comprises a proton-conductive membrane. 
     
     
         20 . The method of  claim 15 , wherein the hydrogen-containing gas comprises at least one gas selected from the group consisting of hydrogen gas, a hydrocarbon gas, ammonia gas, and any combination thereof. 
     
     
         21 . The method of  claim 15 , wherein the temperature needed to maintain ionic mobility at or above a predetermined level ranges between about 300° C. and about 1000° C. 
     
     
         22 . The method of  claim 15 , wherein at least one of the first electrode or the second electrode comprises a material that is catalytically active toward reacting the ionic species to form water.