Patent ID: 12233380

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Referring toFIG.1, an electrolysis cell1has a cathode2on the cathode side21and an anode3on the anode side31. The anode and cathode are configured on opposing sides of an anion conducting membrane10. The cathode is made up of a cathode chamber4, a cathode gas diffusion layer5, and a cathode catalyst layer6. The anode comprises an anode chamber7, an anode porous current collector8, and an anode catalyst layer9. The anion conducting membrane assembly100includes the anode catalyst layer, anion conducting membrane and the cathode catalyst layer, and may also include the cathode gas diffusion layer and the anode porous current collector. The anion conducting membrane10may be a composite anion conducting membrane and may include a support material112, such as a support layer or membrane, and an anion conducting polymer110. A composite anion conducting membrane may be more durable and robust and enable the anion conducting membrane to be made thinner. As shown inFIG.1, a power supply70is coupled across the anode and cathode to produce a potential across the anode and cathode for driving electrolysis. It is to be understood that a power supply is required for the system but is not shown in subsequent figures for clarity.

Referring toFIG.2, an electrolysis cell1has a cathode2and anode3configured on opposing sides of an anion conducting membrane10. Water enters the anode of the system and is transferred across the anion conducting membrane to the cathode where it reacts with oxygen at the cathode side to form hydroxyl ions, as shown in the equation on the cathode side (2H2O+O2+4e+4OH−). The hydroxyl ions are transported to the anode of the electrolysis cell and react to form water and oxygen as shown in the equation on the anode side of the electrolysis cell (4OH−→2H2O+O2+4e−). In this electrolysis cell oxygen is being reduced via reaction on the cathode side of the electrolysis cell. The cathode is made up of a cathode chamber4, a cathode gas diffusion layer5, and a cathode catalyst layer6. The anode comprises an anode chamber7, an anode porous current collector8, and an anode catalyst layer9.

Referring toFIG.3, an electrolysis cell1has a cathode2on the cathode side21and an anode3on the anode side31. The anode and cathode are configured on opposing sides of an anion conducting membrane10. Water enters the anode of the system and is transferred across the anion conducting membrane to the cathode, and reacts with oxygen at the cathode side to form hydroxyl ions, as shown in the equation on the cathode side (2H2O+O2+4e31→4OH−). The hydroxyl ions react with carbon dioxide to form bicarbonate and carbonate. The hydroxyl ions, carbonate and bicarbonate transport to the anode of the electrolysis cell and react to form water, carbon dioxide, and oxygen. In this electrolysis cell carbon dioxide is being reduced via reaction on the cathode side of the electrolysis cell.

Also shown inFIG.3, is an equilibrium reaction that occurs on the cathode side of the electrolysis cell, wherein carbon dioxide and hydroxyl groups react to form bicarbonate, (CO2+OH+→HCO3−). The bicarbonate ion is transferred across the anion conducting membrane to the anode side where it reforms carbon dioxide and hydroxyl groups (HCO331→CO2+OH−).

Referring toFIG.4, water and an electrolyte, an electrolyte solution20, flow in an electrolyte loop22from an electrolyte solution reservoir12to the anode side31of the electrolysis cell1and back to the electrolyte solution tank. The electrolyte solution reservoir may be a closed loop for a period of time and may receive additional electrolyte solution periodically as required. On the cathode side, oxygen is removed from the cathode enclosure gas55, that flows from the cathode enclosure11to the cathode. The reaction on the cathode side of the electrolysis cell is 2H2O+O2+4e−→4OH−, thereby forming a higher concentration of nitrogen in the cathode enclosure11. Note, that the electrolysis cell1may be operated without a cathode enclosure and the cathode may receive a cathode inlet gas flow from the environment.

Referring toFIG.5, a water make-up system13is attached to the electrolyte loop. The water make-up system adds water to the electrolyte loop22as water is transferred across the anion conducting membrane10to the cathode. The water make-up system maintains the pH of the electrolyte solution20in the electrolyte loop22. The flow of electrolyte solution in the electrolyte loop may be controlled by the exit flow from the anode, as indicated by the bold arrow exiting the anode. The water make-up system may receive water from a water source33, or may receive water that has been collected by a water reclamation device30, such as a condenser. The water collected by the water reclamation device may be pumped by a pump32to the water make-up system13or electrolyte solution loop22through a conduit34. Note that the water or moisture collected by water reclamation device may flow be gravity from the cathode side21to the water make-up system13coupled to the anode side31.

Also shown inFIG.5, is an optional electrolyte pump14that is connected to the electrolyte loop22to force flow of the electrolyte solution20to the anode chamber. An optional oxygen removal system15is connected to the electrolyte loop to remove additional oxygen from the closed loop. An exemplary oxygen removal system may allow the release of oxygen from the anode side of the electrolysis cell, such as through venting. An exemplary oxygen removal system may draw oxygen from the head space28in the electrolyte solution reservoir12and/or may employ a check valve25and/or a selectively permeable membrane27. An exemplary check valve may be a flap or a pressure controlled device that may open periodically or on a controlled schedule. An electrolyte solution sensor29may be configured to determine when additional electrolyte or water is required to replenish the system.

An exemplary electrolyte solution sensor may be a level sensor that detects when the electrolyte solution level drops below a certain level, or may be a pH sensor that measures the pH of the electrolyte solution and initiates replenishment when the pH exceeds a threshold level.

Carbon dioxide on the anode side may also be released from the anode side of the electrolysis cell, such as through venting from the head space. An exemplary carbon dioxide removal system may draw carbon dioxide from the head space28in the electrolyte solution reservoir12and/or may employ a check valve25and/or a selectively permeable membrane27. An exemplary check valve may be a flap or a pressure controlled device that may open periodically or on a controlled schedule.

An electrolyte solution sensor heater36may be configured to heat the electrolyte solution20and an electrolyte solution temperature sensor39may monitor the electrolyte solution temperature and initiate heating through the controller90, when the electrolyte solution temperature drops below a threshold level. An increased temperature of the electrolyte solution will increase the reaction rate as it improves the kinetics of reaction.

Also shown inFIG.5, is an optional an air moving device16that is connected to the cathode feed side from the enclosure to improve oxygen flow to the cathode. An air moving device may be a fan, pump or other suitable device.

As shown inFIG.5, an optional electrolysis cell heater51is configured to heat at least a portion of the cell, such as the anode, or the anode side of the anion conducting membrane assembly100. An electrolysis cell temperature sensor59may monitor the electrolysis cell temperature and initiate heating through the controller90, when the electrolysis cell temperature drops below a threshold level. An increased temperature of the electrolyte cell, and particularly the anode or the anode cathode layer will increase the reaction rate as it improves the kinetics of reaction.

A scrubber40may be configured between the cathode enclosure11and the cathode2to reduce and/or remove one or more of the components of the enclosure gas55, such as carbon dioxide. A scrubber, such as a carbon dioxide scrubber, may be a piece of equipment that absorbs carbon dioxide (CO2). An exemplary carbon dioxide scrubber may comprise an amine scrubber that utilizes an amine to react with the carbon dioxide, a mineral scrubber that may utilize a mineral or zeolite to react with the carbon dioxide, a sodium hydroxide scrubber that utilizes sodium hydroxide to react with carbon dioxide, a lithium hydroxide that utilizes lithium hydroxide to react with carbon dioxide, an absorptive scrubber that uses an absorber, such as activated carbon or metal-organic frameworks (MOFs) to absorb the carbon dioxide.

An oxygen sensor19may be configured to monitor the oxygen level of the cathode side21and/or the cathode enclosure11. The controller90may change the power provided to the electrolysis cell1when the oxygen level exceeds a threshold value.

A controller90, may interface with the various components of the anion electrolysis cell1and may control when the components are turned on or activated as a function of sensor input. A cathode enclosure sensor19may monitor the concentration of gases within the cathode enclosure, such as oxygen, nitrogen and/or carbon dioxide and may provide input to the controller90. The controller may change the potential between the anode and cathode or electrical current thereto to maintain a gas level within a desired gas concentration threshold.

Referring toFIG.6, a first electrolysis cell1is in series with a second electrolysis cell1′. The second electrolysis cell1′ has a cathode2′ and anode3′ configured on opposing sides of an anion conducting membrane10′. The cathode enclosure contains a cathode enclosure gas55. The first electrolysis cell is carbon dioxide removal cell that receives an inlet gas56from the cathode enclosure11and removes carbon dioxide via reaction on the cathode to produce a reduce carbon dioxide gas57. The reduce carbon dioxide gas is then fed to the second electrolysis cell1′, an oxygen depletion cell, that produces an outlet gas58having a reduced oxygen concentration, wherein the reduce carbon dioxide gas is reacted on the cathode of the oxygen depletion cell to reduce an oxygen concentration from that of the reduce carbon dioxide gas. The outlet gas is then fed back to the cathode enclosure. Also, carbon dioxide from the carbon dioxide removal cell may be fed from the anode back to the enclosure, effectively maintaining the carbon dioxide levels in the enclosure while reducing the oxygen levels.

In an alternative embodiment, the inlet gas to the carbon dioxide reducing cell is from an ambient environment, or another enclosure wherein the inlet gas may be pre-treated or conditioned, such as by scrubbing to protect the catalyst of the catalyst layers. The outlet form the second electrolysis cell, the oxygen depletion cell, may flow to the cathode enclosure and the cathode enclosure may have a release vent, to enable a flow of conditioned and environmentally controlled gas to flow therethrough.

It will be apparent to those skilled in the art that various modifications, combinations and variations can be made in the present invention without departing from the scope of the invention. Specific embodiments, features and elements described herein may be modified, and/or combined in any suitable manner. Thus, it is intended that the present invention cover the modifications, combinations and variations of this invention provided they come within the scope of the appended claims and their equivalents.