Water splitting system for hydrogen and oxygen separation in the absence of an ion exchange membrane

Abstract

Systems and processes for the production of hydrogen (H2) gas and oxygen (O2) gas from an aqueous electrolyte solution are described. A water-splitting system can include a reactor that includes H2 and O2 generating chambers that can be separate chambers but are not separated by a H2 and/or O2 gas permeable material. The H2 generating chamber can include a cathode and at least a first fluid inlet. The O2 generating chamber can include an anode in electrical communication with the cathode and at least a first fluid inlet. The first and second fluid inlets can each be configured to receive a purged electrolyte solution, a purge gas, or a mixture thereof.

1 . A water-splitting system for the production of hydrogen (H 2 ) gas and oxygen (O 2 ) gas from an aqueous electrolyte solution, the system comprising:
 a reactor comprising:   a H 2  generating chamber comprising a cathode and at least a first fluid inlet fluidly coupled to a purged electrolyte source, a purge gas source, or a combination thereof; an O 2  generating chamber comprising an anode in electrical communication with the cathode and at least a first fluid inlet fluidly coupled to the purged electrolyte source, the purge gas source, or a combination thereof, and   a fluid mover for moving degassed electrolyte solution to the H 2  generating chamber electrolyte inlet and the O 2  generating chamber inlet via degassed electrolyte solution outlet and piping;   wherein the piping fluidly couples the H 2  generating chamber with the O 2  generating chamber, and   wherein the H 2  and O 2  generating chambers are coupled by one or more apertures.   
     
     
         2 . The water-splitting system of  claim 1 , wherein the H 2  or O 2  gas permeable material is a membrane. 
     
     
         3 . The water-splitting system of  claim 1 , further comprising a H 2  reservoir fluidly coupled to the H 2  generating chamber, the purged electrolyte source and an H 2  product outlet. 
     
     
         4 . The water-splitting system of  claim 3 , further comprising a H 2  purification system, fluidly coupled to the H 2  product outlet. 
     
     
         5 . The water-splitting system  claim 1 , further comprising an O 2  reservoir fluidly coupled to the O 2  generating chamber, the purged electrolyte source, and an O 2  product outlet. 
     
     
         6 . The water-splitting system of  claim 5 , further comprising an O 2  purification system, fluidly coupled to the O 2  product outlet. 
     
     
         7 . The water-splitting system of  claim 1 , wherein purged electrolyte source is fluidly coupled to the purge gas source. 
     
     
         8 . The water-splitting system of  claim 1 , wherein the first fluid inlets are fluidly coupled to the purged electrolyte source, and wherein the H 2  generating chamber further comprises a second inlet and/or the O 2  generating chamber further comprises a second inlet, each second inlet fluidly coupled to the purge gas source. 
     
     
         9 . (canceled) 
     
     
         10 . The water-splitting system of  claim 1 , further comprising a conduit coupled to the H 2  generating chamber and the O 2  generating chamber, the conduit comprising a first aperture coupled to the H 2  generating chamber and a second aperture coupled to the O 2  generating chamber. 
     
     
         11 . The water-splitting system of  claim 1 , wherein the anode and the cathode are comprised in a H 2  and/or O 2  gas impermeable material positioned at least partially between the H 2  generating chamber and the O 2  generating chamber. 
     
     
         12 - 15 . (canceled) 
     
     
         16 . A water-splitting process for the production of hydrogen (H 2 ) gas and oxygen (O 2 ) gas, the process comprising:
 (a) providing an electrolyte solution to each of the H 2  generating chamber and the O 2  generating chamber of the water-splitting system of  claims 1  to  8  and  10  to  11 , the electrolyte solution comprising water, a purge gas, and an electrolyte;   (b) subjecting the electrolyte solution in the H 2  generating chamber and the electrolyte solution in the O 2  generating chamber to conditions sufficient to produce a H 2  containing electrolyte solution in the H 2  generating chamber and an O 2  containing electrolyte solution in the O 2  generating chamber, wherein at least a portion of the generated H 2  is dissolved in the H 2  containing aqueous electrolyte solution, and at least a portion of the generated O 2  is dissolved in the O 2  containing electrolyte solution; and   (c) subjecting the H 2  containing electrolyte solution and/or the O 2  containing electrolyte solution to conditions suitable to produce a purge gas containing electrolyte solution, a gaseous H 2  stream, a gaseous O 2  stream, or combinations thereof.   
     
     
         17 . The process of  claim 16 , further comprising:
 providing the purge gas containing electrolyte solution to the H 2  generating chamber of the water-splitting system, the O 2  generating chamber of the water-splitting system, or both, wherein the purge gas containing electrolyte solution comprises H 2  and O 2  in a molar H 2 /O 2  ratio under the explosion limit; and/or   providing a purge gas to the H 2  generating chamber, the O 2  generating chamber, or both; and providing the purged electrolyte solution to the H 2  generating chamber and the O 2  generating chamber.   
     
     
         18 . The process of  claim 16 , wherein the water-splitting conditions comprise a pressure of 0.010 MPa to 2.1 MPa, a temperature of 5° C. to 100° C., a pH of 0 to 14, or a combination thereof. 
     
     
         19 . The process of  claim 16 , wherein the purge gas reduces contamination of H 2  into the O 2  containing aqueous electrolyte stream, O 2  into the H 2  containing aqueous electrolyte stream, or both. 
     
     
         20 . The process of  claim 16 , wherein:
 step (c) comprises:
 (i) compressing the H 2  containing aqueous electrolyte solution stream to produce a gaseous H 2  stream and the electrolyte solution comprising the purge gas, or 
 (i) collecting the H 2  containing aqueous electrolyte solution stream in the H 2  reservoir, the O 2  containing aqueous electrolyte solution stream in the O 2  reservoir or both; 
 (ii) separating the H 2  gaseous stream from the H 2  containing aqueous electrolyte solution and the O 2  gaseous stream from the O 2  containing aqueous electrolyte solution, or both; 
 (iii) forming an aqueous electrolyte solution comprising residual H 2 , O 2 , or both; and 
 (iv) purging the step (iii) aqueous electrolyte solution with the purge gas to form the purge gas containing aqueous electrolyte solution; and/or 
   step (b) further comprises flowing the a portion of the electrolyte solution between the H 2  generating chamber and the O 2  generating chamber through at least one of the apertures of  claim 10 .