Devices, systems, and methods for electrochemically purifying hydrogen

Abstract

A hydrogen gas purifier electrochemical cell (10, 50, 150), a system (200) for purifying hydrogen gas, and a method for purifying hydrogen gas are provided. The cell, system, and method use a dual membrane electrode (DMEA) electrochemical cell (24, 26, 152) that improves purification while avoiding the complexity and cost of conventional cells. The purity of the hydrogen gas produced by the cell, system, and method can be improved by removing at least some intermediate gas impurities from the cell. The purity of the hydrogen gas produced by the cell, system, and method can also be improved by introducing hydrogen gas into the cell to replenish lost hydrogen. A water electrolysis electrochemical cell (250) and a method for electrolyzing water to produce hydrogen gas are also disclosed.

Description

Technology Field

[0001] This application claims priority to U.S. Patent Application No. 17 / 934,341, which is under examination and was filed on September 22, 2022, the disclosures of which are incorporated herein by reference in their entirety.

[0002] The present invention generally relates to the electrochemical purification and / or compression of hydrogen gas. Specifically, aspects of the present invention include an electrochemical cell, system, and method for purifying and / or compressing hydrogen gas using one or more membrane electrode assemblies (MEAs) in a single MEA cell and avoiding external processing of gas flow between separate MEA cells. Background Technology

[0003] As is known in the relevant technical field, there are many uses for high-purity hydrogen, that is, hydrogen gas with a hydrogen content exceeding 99.99 percent by volume. However, hydrogen gas is typically found mixed with other undesirable gases, such as, for example, nitrogen, argon, carbon dioxide, oxygen, and carbon monoxide. Therefore, there is a need in the field for an improved method to separate hydrogen gas from undesirable gases to provide hydrogen gas in a purer form.

[0004] Hydrogen purification is not easily achieved. Hydrogen gas is generally difficult to separate from other gases, primarily because hydrogen molecules are relatively small and hydrogen gas is flammable. Existing means for purifying hydrogen gas from undesirable non-hydrogen gases include molecular sieves, membranes, palladium membranes, and electrochemical hydrogen pumps (EHP).

[0005] Molecular sieves separate hydrogen molecules through selective adsorption, preferentially retaining some molecules over others. However, in many cases, molecular sieve adsorption systems have an undesirably minor effect on the purity of hydrogen gas. One such case is the separation of nitrogen gas (N2) and hydrogen gas (H2).

[0006] Palladium selectively allows only hydrogen atoms to pass through the metal, generating very pure hydrogen. However, palladium is expensive, the process requires compressed gas, and high hydrogen recovery rates require high pressure and / or large quantities of palladium.

[0007] Electrochemical hydrogen pumps (EHPs) selectively extract hydrogen from a mixture of hydrogen gas and other gases, such as nitrogen and argon. However, other undesirable gases typically diffuse through the pump's membrane, resulting in limited hydrogen gas purity. Consequently, one may attempt to increase hydrogen gas purity by using multiple individual electrochemical hydrogen pumps, where each EHP utilizes a separate hardware and control system, with associated housings, cell stacks, feed conduits, and exhaust conduits connected in series to purify the hydrogen gas stream twice. However, this configuration requires multiple separate electrochemical pump cell stacks and multiple sets of connected electrochemical stack hardware. This leads to undesirably increased system complexity and costs.

[0008] Another approach to purifying hydrogen is to increase the membrane thickness in electrochemical cells. However, increasing membrane thickness is generally limited to reducing the diffusion of impurities through the membrane as a function of membrane thickness. Other approaches to purifying hydrogen gas require undesirable gas compression, undesirable multiple pumps, recover less hydrogen gas, consume more energy, and / or fail to produce the high-purity hydrogen gas required by today's hydrogen gas users, such as the semiconductor industry.

[0009] Therefore, there is a need in the relevant technical field for improved hydrogen purification systems, methods, and devices.

[0010] Embodiments of the present invention address this recognized need by providing improved hydrogen purification capable of meeting and exceeding the hydrogen gas purity required in various applications in various aspects. An aspect of the present invention utilizes a unique combination of membrane electrode assemblies (MEAs) or "dual" MEAs (DMEAs) that has been shown to provide the enhanced hydrogen gas purity required by today's users.

[0011] One embodiment of the present invention comprises a hydrogen gas purifier cell having or including the following: a first membrane electrode assembly (MEA) comprising: a first anode positioned to contact a first gas stream having a first hydrogen gas content and a first impurity gas content, wherein the first anode comprises a catalyst, e.g., a platinum group-containing catalyst, adapted to oxidize at least a portion of the first hydrogen gas content to generate hydrogen ions and electrons; a first electrolyte, e.g., an acidic electrolyte, positioned and adapted to receive and deliver at least a portion of the hydrogen ions generated by the first anode; and a first cathode positioned to receive at least a portion of the hydrogen ions delivered by the first electrolyte, wherein the first cathode comprises a catalyst adapted to reduce at least a portion of the hydrogen ions to generate a second gas stream having a second hydrogen gas content greater than the first hydrogen gas content and a second impurity gas content less than the first impurity gas content; A second MEA comprising: a second anode positioned to receive a second gas stream from a first cathode of a first MEA, wherein the second anode contains a catalyst adapted to oxidize at least a portion of a second hydrogen gas content in the second gas stream to generate hydrogen ions and electrons; a second electrolyte, for example, an acidic electrolyte, positioned and adapted to receive and deliver at least a portion of the hydrogen ions generated by the second anode; and a second cathode positioned to receive at least a portion of the hydrogen ions delivered by the second electrolyte of the second MEA, wherein the second cathode contains a catalyst adapted to reduce at least a portion of the hydrogen ions and electrons to generate a third gas stream having a third hydrogen gas content greater than the first hydrogen gas content and a third impurity gas content smaller than the first impurity gas content.

[0012] In one aspect, the purifier cell may further include at least one passage for discharging at least a portion of the second gas stream between the first electrolyte and the second electrolyte. For example, at least one passage may be located between the first cathode and the second anode. In one aspect, at least one passage located between the first cathode and the second anode may include a space or void between the junction surfaces of the first cathode and the second anode. In another aspect, the purifier cell may further include a gas permeable layer or a gas diffusion layer (GDL) between the first cathode and the second anode, and the GDL may provide at least one passage for discharging at least a portion of the second gas stream. In another aspect, a gas distribution or flow field insert with or without a GDL may be placed between the first cathode and the second anode to facilitate or enhance the distribution of the second gas stream across the surface of the second anode. The flow field insert may be an electrically conductive porous or perforated plate, e.g., a porous or perforated metal plate, or a screen-type insert, e.g., a metal screen-type insert, and is positioned and adapted to provide at least some gas distribution to the surface of the second anode. In another aspect, at least one passage for discharging at least some of the second gas stream may be at least one channel very close to the first cathode, the second anode, or both.

[0013] In another aspect, the purifier cell may further include or be provided with at least one passage between the first electrolyte and the second electrolyte to introduce a hydrogen-containing gas into the second gas stream. For example, at least one passage may be located between the first cathode and the second anode. In one aspect, at least one passage may be a space or void between the junction surfaces of the first cathode and the second anode. In one aspect, the purifier cell may further include a gas-permeable layer or a gas-diffusion layer (GDL) between the first cathode and the second anode, and the GDL may provide at least one passage for introducing the hydrogen-containing gas into the second gas stream. In another aspect, a gas distribution or flow field insert with or without a GDL may be placed between the first cathode and the second anode to facilitate or enhance the distribution of the second gas stream across the surface of the second anode. The flow field insert may be a porous or perforated plate, e.g., a porous or perforated metal plate, or a screen-type insert, e.g., a metal screen-type insert, and is positioned and adapted to provide at least some gas distribution to the second anode surface.

[0014] In another aspect, at least one passage for introducing a hydrogen-containing gas into a second gas stream may include at least one channel very close to the first cathode, the second anode, or both.

[0015] In one aspect, the first gas stream may have a first gas pressure and the third gas stream may have a third gas pressure, where the third gas pressure is greater than the first gas pressure. In another aspect, the third gas pressure may be less than the first gas pressure.

[0016] Another embodiment of the present invention is A hydrogen gas purification system comprises or is equipped with the following: at least one hydrogen gas purifier cell as disclosed herein; and at least two electrically conductive plates, wherein one of the at least two plates is mounted at a first end of the at least one hydrogen gas purifier cell, and one of the at least two plates is mounted at a second end of the at least one hydrogen gas purifier cell opposite to the first end. For example, in one aspect, the at least one hydrogen gas purifier cell may comprise a plurality of hydrogen gas purifier cells, for example, a stack of hydrogen gas purifier cells.

[0017] Another embodiment of the present invention is a method for reducing the impurity gas content of a gas stream having a hydrogen gas content and an impurity gas content, the method comprising: introducing a first gas stream having a first hydrogen content and a first impurity gas content into a first anode containing a catalyst; catalytically oxidizing at least a portion of the first hydrogen gas content at the first anode to generate hydrogen ions and electrons; transferring at least a portion of the hydrogen ions and at least a portion of the impurity gas content through a first electrolyte to a first cathode containing a catalyst; catalytically reducing at least a portion of the hydrogen ions transferred through the first electrolyte at the first cathode to generate a second gas stream having a second hydrogen content greater than the first hydrogen content and a second impurity gas content less than the first impurity gas content; introducing a second gas stream into a second anode having a catalyst; and catalytically oxidizing at least a portion of the second hydrogen gas content in the second gas stream at the second anode to generate hydrogen ions and electrons. A step of transferring at least a portion of the hydrogen ions generated at the second anode and at least a portion of the second impurity gas content to the second cathode through the second electrolyte; and a step of catalytically reducing at least a portion of the hydrogen ions transferred through the second electrolyte to the second cathode to produce a third gas stream having a third hydrogen content greater than the first hydrogen content and a third impurity gas content smaller than the first impurity gas content.

[0018] In one aspect, the method may further include the step of removing at least a portion of the second gas stream to produce a modified gas stream having a non-hydrogen gas partial pressure lower than the non-hydrogen gas partial pressure in the second gas stream. In another aspect, the step of introducing the second gas stream into the second anode includes the step of introducing the modified gas stream into the second anode. In one aspect, the step of removing at least a portion of the second gas stream may be performed by removing at least a portion of the second gas stream through a passage between the first electrolyte and the second electrolyte, for example, said passage may be located between the first cathode and the second anode. In one aspect, the passage for removing at least a portion of the second gas stream may be a space or void between the junction surfaces of the first cathode and the second anode. In another aspect, the step of removing at least a portion of the second gas stream may be performed by removing at least a portion of the second gas stream through a gas diffusion layer (GDL) and / or a flow field insert disposed between the first cathode and the second anode. In another aspect, the step of removing at least a portion of the second gas stream may be performed by removing at least a portion of the second gas stream through at least one channel very close to the first cathode, the second cathode, or both.

[0019] In another aspect, the method may also include the step of introducing some hydrogen gas into a second gas stream, e.g., a "replenishment" gas stream. In one aspect, the step of introducing some hydrogen gas into the second gas stream may replenish at least some hydrogen gas removed from the second gas stream. In one aspect, the replenishment hydrogen gas stream may include at least a portion of a third gas stream having a third hydrogen content. For example, the third gas stream may be introduced into the second gas stream by diffusion through a second electrolyte. Such diffusion through the second electrolyte may be referred to as "reverse diffusion" of at least a portion of the third gas stream having a third hydrogen content into the second gas stream through the second electrolyte.

[0020] In one aspect, by using the electrochemical cell and method disclosed herein, the purified hydrogen gas produced, e.g., a third impurity gas content, may be at least 100 times lower on a volume basis than the impurity content of the input gas content, e.g., a first impurity gas content. In another aspect, the impurity gas content of the produced hydrogen gas may be at least 1,000 times, 10,000 times, 100,000 times, or even 1,000,000 times lower or less than the impurity content of the first hydrogen gas stream.

[0021] In one aspect, the impurity gas content of the hydrogen gas produced by any of the method, cell, and system of the present invention may be, for example, up to 100 parts per million [ppm] in a third gas stream, that is, the third gas stream may contain up to 100 ppm of impurity gas. In another aspect of the present invention, the impurity gas content of the produced hydrogen gas is It may be up to 20 ppm, or up to 10 ppm; or up to 5 ppm, or up to 2 ppm, or up to 1 ppm. In another aspect of the present invention, the impurity gas content of the generated hydrogen gas is It may be up to 750 parts per billion [ppb] (i.e., up to 0.750 ppm); or up to 500 ppb; or up to 200 ppb; or even up to 100 ppb. As is known in the art, such impurity content of the generated hydrogen gas, for example, a content 1,000 times lower than the impurity gas content of the first gas stream, or an impurity gas content in ppm or ppb units, is generally the “dry basis.” As is known in the art, the “dry basis” means that the generated gas stream may still contain some water vapor to be reduced or removed, for example, in a subsequent drying process.

[0022] Another embodiment of the present invention is a method for reducing the impurity gas content of a gas stream having a hydrogen gas content and an impurity gas content, the method comprising: introducing a first gas stream having a first hydrogen content and a first impurity gas content into a first membrane electrode assembly (MEA) having a first anode, a first electrolyte, and a first cathode having a catalyst to produce a second gas stream having a second hydrogen gas content and a second impurity gas content; and passing the second gas stream directly through a second MEA having a second anode, a second electrolyte, and a second cathode having a catalyst to produce a third gas stream having a third hydrogen gas content greater than the first hydrogen content and a third impurity gas content less than the first impurity gas content.

[0023] In one aspect, the first MEA and the second MEA may be placed in a hydrogen purifier cell, and the step of passing the second gas stream directly into the second MEA may include the step of passing the second gas stream into the second MEA while preventing the second gas stream from escaping the hydrogen purifier cell.

[0024] In one aspect, the method may further include the step of removing at least a portion of the second gas stream to produce a modified second gas stream having a reduced non-hydrogen gas partial pressure compared to the second gas stream, and then introducing the modified second gas stream having the reduced non-hydrogen gas partial pressure into the second MEA. In one aspect, the method may further include the step of introducing at least a portion of hydrogen gas into the second gas stream or the modified second gas stream.

[0025] Further embodiments of the present invention are hydrogen gas purifier cells comprising: a membrane electrode assembly (MEA) comprising: an anode positioned to contact a first gas stream having a first hydrogen gas content and a first impurity gas content, wherein the anode contains a catalyst adapted to oxidize at least a portion of the first hydrogen gas content to generate hydrogen ions and electrons; a first electrolyte positioned and adapted to receive and deliver at least a portion of the hydrogen ions received from the anode; a dual electrode positioned to receive at least a portion of the hydrogen ions delivered by the first electrolyte, wherein the dual cathode contains a catalyst adapted to generate a second gas stream having a second hydrogen gas content and to reduce at least a portion of the hydrogen ions to oxidize at least a portion of the second hydrogen gas content in the second gas stream to generate hydrogen ions and electrons; and a second electrolyte positioned and adapted to receive and deliver at least a portion of the hydrogen ions received from the dual electrode. A membrane electrode assembly (MEA) comprising a cathode positioned to receive at least a portion of hydrogen ions delivered by a second electrolyte, wherein the cathode comprises a catalyst adapted to reduce at least a portion of the hydrogen ions to produce a third gas stream having a third hydrogen gas content greater than a first hydrogen gas content and a third impurity gas content less than a first impurity gas content.

[0026] In one aspect, the hydrogen gas purifier cell further comprises at least one passage for removing at least a portion of the second gas stream. For example, the at least one passage for removing at least a portion of the second gas stream may be a dual electrode, e.g., a permeable layer of the dual electrode; a gas permeable diffusion layer; and / or a second electrolyte.

[0027] In one aspect, the hydrogen gas purifier cell further comprises at least one passage for introducing at least some hydrogen gas into a second gas stream. For example, the at least one passage for introducing at least some hydrogen gas may be a dual electrode, e.g., permeability of the dual electrode; a gas-permeable diffusion layer; and / or a second electrolyte, e.g., through "reverse diffusion".

[0028] Further embodiments of the present invention are methods for purifying hydrogen gas, comprising: introducing a first gas stream having a first hydrogen gas content and a first impurity gas content into an anode containing a catalyst; catalytically oxidizing at least a portion of the first hydrogen gas content at the anode to generate hydrogen ions and electrons; transferring at least a portion of the hydrogen ions generated at the anode to a dual electrode through a first electrolyte; catalytically reducing at least a portion of the hydrogen ions transferred through the first electrolyte at the dual electrode to generate a second gas stream having a second hydrogen gas content, and catalytically oxidizing at least a portion of the second hydrogen gas content in the second gas stream to generate hydrogen ions and electrons; transferring at least a portion of the hydrogen ions generated at the dual electrode to a cathode through a second electrolyte, and catalytically reducing at least a portion of the hydrogen ions transferred through the second electrolyte at the cathode to generate a third gas stream having a third hydrogen gas content greater than the first hydrogen gas content and a third impurity gas content less than the first impurity gas content.

[0029] In one aspect, the method may further include the step of removing at least a portion of a second gas stream, for example, through at least one passage. For example, at least one passage for removing at least a portion of the second gas stream may be a gas diffusion layer; a gas-permeable dual electrode; and / or a second electrolyte, for example, through "reverse diffusion".

[0030] In one aspect, the method may further include the step of introducing at least some hydrogen gas into a second gas stream, for example, through at least one passage. For example, at least one passage for introducing at least some hydrogen gas may be made through a gas diffusion layer; through a gas-permeable dual electrode; and / or through a second electrolyte.

[0031] Another additional embodiment of the present invention is a water electrolytic cell comprising: a first membrane electrode assembly (MEA); a first anode positioned to contact a first H2O-containing fluid stream, wherein the first anode [contains] the H2O of the first H2O-containing fluid stream to generate oxygen gas, hydrogen ions, and electrons. A first membrane electrode assembly (MEA) comprising: a first anode having a catalyst adapted to oxidize at least a portion of; a first electrolyte arranged and adapted to receive and deliver at least a portion of the hydrogen ions generated by the first anode; and a first cathode arranged to receive at least a portion of the hydrogen ions delivered by the first electrolyte, wherein the first cathode has a catalyst adapted to reduce at least a portion of the hydrogen ions to produce a second fluid stream containing hydrogen gas; a second MEA comprising: a second anode arranged to receive a second fluid stream containing hydrogen gas from the first cathode of the first MEA, wherein the second anode has a catalyst adapted to oxidize at least a portion of the hydrogen gas to produce hydrogen ions and electrons; and a second electrolyte arranged and adapted to receive and deliver at least a portion of the hydrogen ions generated by the second anode. A second MEA comprising a second cathode positioned to receive at least a portion of hydrogen ions delivered by a second electrolyte of the second MEA, wherein the second cathode comprises a catalyst adapted to reduce at least a portion of the hydrogen ions to produce a third fluid stream containing hydrogen gas.

[0032] In one aspect, the electrolytic cell may further include at least one passage for discharging at least a portion of a second fluid stream between the first electrolyte and the second electrolyte. For example, the passage for discharging the second fluid stream may be located between the first cathode and the second anode. For example, the at least one passage located between the first cathode and the second anode may be a void between the junction surfaces of the first cathode and the second anode; and / or a gas permeable layer (GDL) and / or a flow field insert between the first cathode and the second anode.

[0033] In another aspect, the water electrolytic cell may further include at least one passage between the first electrolyte and the second electrolyte to introduce a hydrogen-containing gas into a second gas stream. For example, the passage for introducing the hydrogen gas may be a void between the junction surfaces of the first cathode and the second anode; and / or a GDL and / or flow field insert located between the first cathode and the second anode.

[0034] Another embodiment of the present invention is a method for electrolyzing water, the method comprising: introducing a first fluid stream containing H2O into a first anode containing a catalyst; catalytically oxidizing at least a portion of the H2O in the first fluid stream containing H2O at the first anode to produce oxygen gas, hydrogen ions, and electrons; transferring at least a portion of the hydrogen ions through a first electrolyte to a first cathode containing a catalyst; catalytically reducing at least a portion of the hydrogen ions transferred through the first electrolyte at the first cathode to produce a second fluid stream containing hydrogen gas; introducing a second fluid stream containing hydrogen gas into a second anode containing a catalyst; catalytically oxidizing at least a portion of the hydrogen gas in the second fluid stream at the second anode to produce hydrogen ions and electrons; transferring at least a portion of the hydrogen ions produced at the second anode to a second cathode through a second electrolyte; and, at the second cathode, a step of catalytically reducing at least some of the hydrogen ions delivered through the second electrolyte to produce a third fluid stream having hydrogen gas. According to an aspect of the invention, the “fluid stream” may be a liquid stream, a gas stream, and / or a liquid and gas stream.

[0035] In one aspect, the method may further include the step of removing at least a portion of the second fluid stream to produce a modified fluid stream having a non-hydrogen gas partial pressure lower than the non-hydrogen gas partial pressure of the second fluid stream. The method may further include the step of introducing the modified fluid stream into the second anode.

[0036] In another aspect, the method may further include the step of introducing hydrogen gas into the second fluid stream, for example, the introduced hydrogen gas may replenish at least some of the hydrogen gas removed from the second fluid stream.

[0037] Further embodiments of the present invention are water electrolytic cells comprising: a membrane electrode assembly (MEA) comprising: an anode positioned to contact a first H2O-containing fluid stream, wherein the anode contains a catalyst adapted to oxidize at least a portion of the H2O in the first H2O-containing fluid stream to generate oxygen gas, hydrogen ions, and electrons; a first electrolyte positioned and adapted to receive and deliver at least a portion of the hydrogen ions generated at the anode; a dual electrode positioned to receive at least a portion of the hydrogen ions delivered by the first electrolyte, wherein the dual cathode contains a catalyst adapted to reduce at least a portion of the hydrogen ions to generate a second gas stream having a second hydrogen gas content and to oxidize at least a portion of the second hydrogen gas content in the second gas stream to generate hydrogen ions and electrons; and a second electrolyte positioned and adapted to receive and deliver at least a portion of the hydrogen ions received from the dual electrode. A membrane electrode assembly (MEA) comprising a cathode positioned to receive at least a portion of hydrogen ions delivered by a second electrolyte of a second MEA, wherein the cathode comprises a catalyst adapted to reduce at least a portion of the hydrogen ions to produce a third fluid stream containing hydrogen gas.

[0038] Another embodiment of the present invention is a method for electrolyzing water, the method comprising: introducing a first H2O-containing fluid stream into an anode containing a catalyst; catalytically oxidizing at least a portion of the H2O in the first H2O-containing fluid stream at the anode to produce oxygen gas, hydrogen ions, and electrons; transferring at least a portion of the hydrogen ions produced at the anode to a dual electrode through a first electrolyte; catalytically reducing at least a portion of the hydrogen ions transferred through the first electrolyte at the dual electrode to produce a second fluid stream having a second hydrogen gas content, and catalytically oxidizing at least a portion of the second hydrogen gas content in the second gas stream to produce hydrogen ions and electrons; transferring at least a portion of the hydrogen ions produced at the dual electrode to a cathode through a second electrolyte; and catalytically reducing at least a portion of the hydrogen ions transferred through the second electrolyte at the cathode to produce a third fluid stream having hydrogen gas.

[0039] These and other aspects, features, and advantages of the present invention will become clear from the following detailed description of various aspects of the present invention together with the accompanying drawings. Brief explanation of the drawing

[0040] The essence of what is considered to be the invention is specifically pointed out and clearly asserted in the claims at the conclusion of this specification. The foregoing and other objects, features, and advantages of the invention will be readily understood from the following detailed description of aspects of the invention together with the accompanying drawings. FIG. 1 is a schematic diagram of a hydrogen gas purifier cell according to one aspect of the present invention. FIG. 2 is a schematic diagram of a hydrogen gas purifier cell according to another aspect of the present invention. FIG. 3 is a schematic elevation view of a hydrogen purifier stack assembly having a hydrogen gas purifier cell shown in FIG. 1 or FIG. 2 according to an aspect of the present invention. FIG. 3a is a detailed view of the hydrogen purifier stack assembly shown in FIG. 3, identified as detail 3A in FIG. 3. FIG. 3b is a detailed view similar to FIG. 3a according to another aspect of the present invention. FIG. 4 is a schematic elevation view of a hydrogen purifier stack having a plurality of hydrogen purifier cells shown in FIG. 1 and / or FIG. 3, according to one aspect of the present invention. FIG. 5 is a schematic diagram of a hydrogen gas purifier cell according to another aspect of the present invention. FIG. 6 is a schematic diagram of a hydrogen gas purifier system having one or more hydrogen purifiers having one or more hydrogen purifier stacks shown in FIG. 4, according to one aspect of the present invention. FIG. 7 is a schematic diagram of a water electrolytic cell according to another aspect of the present invention. FIG. 8 is a schematic diagram of a water electrolytic cell according to another aspect of the present invention. Specific details for implementing the invention

[0041] FIG. 1 is a schematic diagram of a hydrogen gas purifier cell (10) according to one aspect of the present invention. According to this aspect, the purifier cell (10) is configured and adapted to receive a feed or a first gas stream (12) having at least some hydrogen gas content (14) (i.e., diatomic hydrogen gas, H2) and at least some non-hydrogen gas (16) to produce a gas stream (18) with reduced non-hydrogen gas content, i.e., a gas stream (18) with a purer hydrogen gas content. The non-hydrogen gas (16) may generally include, in particular, nitrogen (N2), argon (Ar), carbon monoxide (CO), methane (CH4), oxygen (O2), and / or carbon dioxide (CO2). According to one aspect of the present invention, the expression “non-hydrogen gas” may refer to a gas other than diatomic hydrogen gas, H2. The reduced non-hydrogen gas content gas stream (18) may be referred to as the exhaust gas stream (18) or the third gas stream (18). The third gas stream (18) may generally include a high-purity hydrogen gas stream having an enhanced hydrogen gas content (20) and a reduced non-hydrogen gas content (22), for example, a non-hydrogen content of up to 100 ppm on a dry basis. In another aspect of the invention, the non-hydrogen content (22) of the gas stream (18) may be up to 20 ppm, or up to 10 ppm; or up to 5 ppm, or up to 2 ppm, or up to 1 ppm. In addition to reducing the content of non-hydrogen gas in the gas stream (18), in an aspect of the invention, the gas stream (18) may generally have an increased hydrogen gas content (20) in volume percent and an increased hydrogen gas pressure, for example, a pressure greater than the pressure of the feed gas stream (12). In one aspect, the pressure of the gas stream (18) may be lower than the pressure of the gas stream (12).Since the desired function of the purifier cell (10) is to reduce or substantially remove the content of non-hydrogen gas (16), the non-hydrogen gas (16) may be referred to as "impurity gas" 16) or "first impurity gas" 16).

[0042] As schematically illustrated in FIG. 1, the hydrogen gas purifier cell (10) generally comprises a multilayer structure having anode and cathode components having a thin planar or thin laminar structure, for example, where the structure illustrated in FIG. 1 may include a side view or cross-sectional view of the purifier cell (10) drawn to facilitate the disclosure of the invention, although the structure is not drawn to scale.

[0043] According to an aspect of the present invention, to provide a desired increased hydrogen gas content (20) and generally increased hydrogen gas pressure, a purifier cell (10) generally comprises a first membrane electrode assembly (MEA) (24) and at least one second MEA (26). The first MEA (24) comprises a first electrode (28), specifically a first "anode" (28), as referred to in the art. The anode (28) and all anodes disclosed herein may generally be gas permeable, specifically hydrogen gas permeable, wherein at least a portion of the hydrogen gas content (14) and at least a portion of the non-hydrogen gas content (16) of the first gas stream (12) may pass through the anode (28), for example, in the axial direction indicated by the arrow of the first gas stream (12). Additionally, the anode (28) and all anodes or cathodes disclosed herein may comprise at least a portion of a catalyst, for example, at least a portion of a platinum group metal-containing catalyst, which converts hydrogen into hydrogen ions (H₂). +To enhance oxidation, for example, a platinum-containing catalyst, but in some respects, a non-platinum group metal-containing catalyst may be used for the anode (28) and any anode or cathode disclosed herein. As is known in the art, a platinum group metal-containing catalyst may be a catalyst containing at least some nickel (Ni), at least some palladium (Pa) and / or at least some platinum (Pt).

[0044] A first anode (28) is positioned to come into contact with a first gas stream (12) having a first hydrogen gas content (14) and a first impurity gas content (16). The relative content of the first hydrogen gas (14) and the first impurity gas content (16) of the first gas stream (12) is schematically illustrated in FIG. 1 and in other drawings is illustrated by partial shading of the arrow identified as the first gas stream (12). This partial shading of the gas stream arrow 12 (and gas stream arrows 38 and 18 in FIG. 1) is for illustrative purposes only and does not represent the actual relative gas content of these gas streams according to aspects of the invention.

[0045] In one aspect, to improve the distribution of the first gas stream (12) over the surface of the anode (28), an electrically conductive gas diffusion layer (GDL) not shown in FIG. 1 may be placed between the first gas stream (12) and the anode (28), for example, the GDL may be applied over the surface of the anode (28) that is in contact with the first gas stream (12). In one aspect, the GDL used in the cell (10) or the GDL layer used in all aspects disclosed herein may be a carbon fiber type GDL, for example, provided by SGL Carbon GmBH or equivalent. In another aspect, a gas distribution or flow field insert (as disclosed herein) with or without the GDL may be placed over the anode (102) to facilitate or improve the distribution of the first gas stream (12) over the surface of the anode (28).

[0046] According to an aspect of the present invention, the catalyst contained in the first anode (28) is a hydrogen ion (H) according to Equation 1 as known in the art. + ) and electrons (e - Promotes or enhances the oxidation of at least hydrogen gas (H2) content (14) introduced into the anode (28) to produce or generate ).

[0047] Equation 1.

[0048] Due to the permeability of the anode (28), hydrogen gas (H2) enters the anode (28), and due to the electrical conductivity of the anode (28), electrons (e - ) is conducted out from the anode (28), and, according to an aspect of the present invention, hydrogen ions (H+) are introduced into the electrolyte (30). As is known in the art, hydrogen ions (H + ) is a proton. However, it is recognized in the industry that at least some undesirable non-hydrogen gas (16) also passes through the anode (28).

[0049] As is common in the art, at least a portion of the input or first gas stream (12) may not be oxidized at the anode (28) and may be removed into a gas stream (13), such as an "exhaust gas stream." Generally, the exhaust stream (13), which typically has a low hydrogen gas content due to the oxidation of hydrogen gas occurring at the first anode (28), may be captured and sent, for example, through channels, manifolds, and ports for further processing or disposed of as necessary.

[0050] The electrolyte (30) or the first electrolyte (30) is hydrogen ions (H + It is positioned and adapted to receive and transmit at least a portion of ). Because the anode (28) is very close to the electrolyte (30), hydrogen ions (H) diffused through the anode (28) + ) and non-hydrogen gas pass from the anode (28) to the electrolyte (30). The first electrolyte (30) includes a barrier between the first anode (28) and the electrode (32). The first electrolyte (30) contains hydrogen ions (H + It may include any material or substance capable of transmitting, for example, hydrogen ions (H+), i.e., protons, which can be selectively transmitted from the first anode (28) to the electrode (32). That is, in one aspect, the electrolyte (30) and any electrolyte disclosed herein may be referred to as a "proton-conducting material" while substantially blocking the flow of gas and electrons. The first electrolyte (30) and any electrolyte disclosed herein may generally be acidic and may be, for example, an acidic polymer containing perfluorosulfonic acid (PFSA). In one aspect, the electrolyte (30) and any electrolyte disclosed herein are Nafion trademarked by The Chemours Company of Wilmington, Delaware. TMIt may be a membrane sold as such or an equivalent. In another aspect, the electrolyte (30) and any electrolyte disclosed herein may contain one or more of the following acids: phosphoric acid [H3PO4], sulfuric acid [H2SO4], or other hydrogen ions (H + ) Conductive acid. In one aspect, the first electrolyte (30) may include a proton exchange membrane (PEM) as is known in the art.

[0051] As is known in the art, the passage of gas through an electrolyte (30) and any electrolyte disclosed herein is driven by a partial pressure gradient of gas across the electrolyte, such as from one side of the electrolyte (30) to another, opposite side of the electrolyte (30). Thus, an undesirable non-hydrogen gas having a sufficient partial pressure gradient can also diffuse through the electrolyte (30) and any electrolyte disclosed herein. In addition to the pressure gradient across the electrolyte, defects in the electrolyte, such as small holes or voids in the electrolyte, can also cause gas to flow undesirably through an electrolyte such as the electrolyte (30).

[0052] As is known in the art, the electrode (32), which may be referred to as a "cathode" 32 or a first cathode (32), is a hydrogen ion (H) delivered by the first electrolyte (30). + It is arranged to receive at least a portion of ). Similar to the first anode (28), the first cathode (32) and any cathode disclosed herein generally receive hydrogen ions (H) passing through the first electrolyte (30) according to Equation 2, as is known in the art, a catalyst. + At least some of ) at least some electrons (e - It includes a platinum group metal-containing catalyst adapted to enhance the reaction (i.e., reduction) with ).

[0053] Equation 2.

[0054] The resulting, or "evolved" hydrogen gas (H2) (34), or second hydrogen gas content (34), and any non-hydrogen gas (36), or second impurity gas content (36) are delivered through the first cathode (32) and are denoted in FIG. 1 as gas stream (38) or second gas stream (38).

[0055] In one aspect, to improve the distribution of hydrogen gas on the surface of the first cathode (32), a gas diffusion layer (GDL) and / or a flow field insert not shown in FIG. 1 may be positioned between the first electrolyte (30) and the first cathode (32). For example, the GDL and / or the flow field insert may be applied over the surface of the first cathode (32).

[0056] According to an aspect of the present invention, the second hydrogen gas content (34) is greater than the first hydrogen gas content (14), and the second impurity gas content (36) is smaller than the first impurity gas content (16).

[0057] As illustrated in FIG. 1, according to an aspect of the invention, a second gas stream (38) having a second hydrogen gas content (34) and a second impurity gas content (36) may subsequently be introduced into a second MEA (26), specifically the electrode (40) or the second anode (40) of the second MEA (26). In the schematic diagram of the purifier cell (10) illustrated in FIG. 1, the first MEA (24) is shown spaced apart from the second MEA (26) to facilitate the description and disclosure of the invention. However, according to an aspect of the invention, the gap between the first MEA (24) and the second MEA (26) may be minimized, for example, when the surface of the first cathode (32) may be adjacent to or in contact with the surface of the second anode (40). However, in one aspect, for example, at least some gap of 0.1 millimeter [mm] to 0.5 mm may exist between the surface of the first cathode (32) and the surface of the second anode (40).

[0058] According to an aspect of the present invention, unlike conventional technology, a second gas stream (38) having a second hydrogen gas content (34) and a second impurity gas content (36) can be introduced into a second MEA (26) without removing or extracting the second gas stream (38) from the purifier cell (10). In other words, while a portion of the gas stream (38) may undesirably "escape" from the purifier cell (10), according to one aspect of the present invention, almost all of the gas stream (38) generated at the first cathode (32) or diffused through the cathode (32) is received by the second anode (40). For example, in one aspect, the second gas stream (38) can be passed from the first cathode (32) of the MEA (24) to the second anode (40) of the MEA (26) without passing outside the cell (10), for example, without any intervening handling or processing. In one aspect, the evolved hydrogen gas (H2) formed at the first cathode (32) can be oxidized substantially immediately into hydrogen ions (H+) at the second anode (40). In one aspect, the second gas stream (38) may be allowed to pass directly from the first cathode (32) of the MEA (24) to the second anode (40) of the MEA (26) of the purifier cell (10) without passing outside the cell (10) before reaching the second cathode (40), for example.

[0059] The second anode (40) is positioned to be in contact with a second gas stream (38) having a second hydrogen gas content (34) and a second impurity gas content (36). The second anode (40) of the second MEA (26) may be similar, if not identical, to the first anode (28) of the MEA (24). The second anode (40) may be hydrogen gas permeable, wherein at least a portion of the hydrogen gas content (34) and at least a portion of the non-hydrogen gas content (36) in the second gas stream (38) may pass through the second anode (40) axially, for example, as indicated by the arrow of the second gas stream (38). Additionally, the second anode (40) comprises at least some catalyst, for example, at least some platinum group metal-containing catalyst, which, as indicated by Equation 1, hydrogen ions (H₂) of the hydrogen gas + ) and electronic(e - It can improve oxidation to ).

[0060] In one aspect, to improve the distribution of the second gas stream (38) on the surface of the second anode (40), a gas diffusion layer or GDL and / or flow field insert not shown in FIG. 1 may be placed between the first cathode (32) and the second anode (40), and, for example, the GDL and / or flow field insert may be applied over the surface of the second anode (40) that is contacted by the second gas stream (38).

[0061] According to an aspect of the present invention, a catalyst included in the second anode (40) promotes or enhances the oxidation of hydrogen gas content (34) introduced into the second anode (40) so as to provide hydrogen ions (H) according to Equation 1. + ) and electrons (e - ) produces or generates. In one aspect, electrons (e) generated at the second anode (40) - ) is directed back to the first cathode (32) as indicated by the arrow (41) in FIG. 1, and hydrogen ions (H) from the first cathode (32) according to Equation 2 +The electrons (e) used to reduce ) to hydrogen (H2) - At least some of the following can be supplied. Due to the permeability of the second anode (40), some impurity gases and any unoxidized hydrogen (H2) may pass through the second anode (40) and, according to an aspect of the invention, are introduced into or come into contact with the electrolyte (42).

[0062] The electrolyte (42) of the MEA (26) or the second electrolyte (42) is hydrogen ions (H) received from the second anode (40). + It is positioned and adapted to receive and transmit at least a portion of the first electrolyte (30). The second electrolyte (42) includes a gas barrier between the second anode (40) and the electrode (44). The second electrolyte (42) may be similar, if not substantially identical, to the first electrolyte (30) and may include any material or substance capable of transmitting hydrogen ions (H+), for example, hydrogen ions (H+), i.e., protons, which can be selectively transmitted from the second anode (40) to the electrode (44). In other words, as mentioned in relation to the electrolyte (30), in one aspect the electrolyte (42) may be referred to as a "proton-conducting material." The second electrolyte (42) may generally be acidic and may contain one or more of the acids identified above in relation to the first electrolyte (30), for example. However, in one aspect the second electrolyte (42) may include a PEM as is known in the art.

[0063] The electrode (44) may be referred to as a "cathode" (44) or a second cathode (44) as is known in the art, and hydrogen ions (H) delivered by the second electrolyte (42) + It is positioned to receive at least some of ). Similar to the second anode (40), the second cathode (44) generally comprises a catalyst, for example, a platinum group metal-containing catalyst, and according to Equation 2, at least some electrons (e - Using ) hydrogen ions (H +It is adapted to enhance the reduction of at least a portion of ). The resulting or “evolved” hydrogen gas (H2) content (20), or third hydrogen gas content (20), and any non-hydrogen gas (22), or second impurity gas content (22) delivered through the electrolyte (30) are indicated in FIG. 1 as gas stream (18) or exhaust gas stream (18) or third gas stream (18).

[0064] In one aspect, hydrogen ions (H) on the surface of the second cathode (44) + To improve the distribution of ), a gas diffusion layer (GDL) and / or a flow field insert not shown in FIG. 1 may be placed between the second electrolyte (42) and the second cathode (44), and, for example, the GDL and / or flow field insert may be applied over the surface of the second cathode (44).

[0065] According to an aspect of the invention, the third hydrogen gas content (20) of the third gas stream (18) is greater than the first hydrogen gas content (14) and the second hydrogen gas content (34); and the third impurity gas content (22) is less than the first impurity gas content (16) and the second impurity gas content (36). However, generally, the third gas stream (18) may have a purity greater than the purity of the first gas stream (12) on a "dry basis" basis. For example, the third hydrogen gas content (20) in the third gas stream (18) may be at least 10% greater than the first hydrogen gas content (14) of the first gas stream (12) on a volume basis. In one aspect, the third hydrogen gas content (20) may be 20 percent to 30 percent greater than the first hydrogen gas content (14) on a volume basis. Additionally, in one aspect, the third gas stream (18) may be at least 1,000 times purer in hydrogen than the first gas stream (12) by volume. In one aspect, the third gas stream (18) may be 10,000 to 10,000,000 times purer in hydrogen than the first gas stream (12) by volume. However, typically, the third gas stream (18) may be 100,000 to 2,000,000 times purer in hydrogen content than the first gas stream (12) by volume. For example, in one aspect, the purity of the third gas stream (18) may be at least 99.99 percent hydrogen by volume, or at least 99.999 (5 9) percent by volume, or 99.9999 (6 9) percent by volume. According to another aspect of the present invention, the purity of the third gas stream (18) can be expressed based on the third impurity gas content (22). For example, in one aspect, the third impurity gas content (22) may be an impurity gas of up to 100 ppm.In another aspect of the present invention, the generated third impurity gas content (22) may be up to 20 ppm, or up to 10 ppm, up to 5 ppm, or up to 2 ppm, or up to 1 ppm. In another aspect of the present invention, the third impurity gas content (22) of the generated hydrogen gas (18) is. It may be up to 750 ppb (i.e., up to 0.750 ppm) or up to 500 ppb or up to 200 ppb; or even up to 100 ppb. As is known in the art, such impurity content of the generated hydrogen gas is generally "dry standard."

[0066] According to an aspect of the present invention, by passing a second gas stream (38) having a hydrogen gas content (34) from the first cathode (32) of the MEA (24) to the second anode (40) of the second MEA (26) in a purifier cell (10), not only can a more compact purifier be provided, but a more efficient device can also be provided and a purer hydrogen gas content (22) than that of the prior art can be provided. Above all, passing the second gas stream (38) directly from the first cathode (32) to the second anode (40), for example, avoids the perceived addition of components that characterize the performance of the prior art hydrogen gas purifier, the loss of efficiency, and the loss of hydrogen gas content.

[0067] Additionally, according to an aspect of the invention, the resulting gas stream, i.e., the third gas stream (18) having a higher hydrogen gas content (20), may generally be provided at a higher pressure than the pressure of the feed or the first gas stream (12). For example, according to an aspect of the invention, if the first gas stream (12) may have a pressure of about 1 pound [psig] per square inch gauge, the third gas stream (18) may have a pressure of at least 150 psig. In one aspect, the pressure of the third gas stream (18) may be at least 120 psig, or at least 200 psig, or even at least 10,000 [10 thousand] psig. In another aspect of the invention, the pressure of the third gas stream (18) cannot be higher than the pressure of the feed or the first gas stream (12). In one aspect, the pressure of the third gas stream (18) can be lower than the pressure of the first gas stream (12).

[0068] FIG. 2 is a schematic diagram of a hydrogen gas purifier cell (50) according to another aspect of the present invention. According to this aspect, the purifier cell (50) may have many features of the purifier cell (10); however, the purifier cell (50) further includes at least one gas discharge or release between the MEAs. According to this aspect, tests have shown that allowing at least a portion of the second gas stream (38 in FIG. 2) to be discharged or escaped from the purifier cell (50), that is, allowing at least a portion of the second gas stream to be removed between the MEAs, produces a higher hydrogen gas content compared to a purifier that does not allow at least a portion of the second gas stream to be removed between the MEAs. Such venting of at least a portion of the second gas stream is believed to reduce the partial pressure of the non-hydrogen gas between the MEAs and thus reduce the undesirable partial pressure gradient kinetic of the non-hydrogen gas through the second MEAs. In addition, since some of the desired hydrogen gas is lost when removing part of the second gas stream, at least some hydrogen gas can be introduced between the MEAs to function as "make-up" hydrogen gas for the hydrogen gas that may be lost while removing part of the second gas stream.

[0069] As illustrated in FIG. 2, in a manner similar to the purifier cell (10), the purifier cell (50) is positioned and adapted to receive a feed similar or identical to the first gas stream (12) illustrated in FIG. 1, or the first gas stream (12) and at least some non-hydrogen gas (16) to produce a gas stream (52) with increased hydrogen gas content and reduced non-hydrogen gas content. The gas stream (52) may be referred to as the exhaust gas stream (52) or the third gas stream (52). Similar to the purifier cell (10), the third gas stream (52) may generally contain an enhanced hydrogen gas content (54) and a reduced non-hydrogen gas content (56). Similar to the purifier cell (10) schematically illustrated in FIG. 2, the hydrogen gas purifier cell (50) generally comprises a multilayer structure having components having a thin planar or thin layered structure, such as an anode and a cathode, wherein the structure illustrated in FIG. 2 may include a side view or a cross-sectional view of the purifier cell (50) illustrated to facilitate the disclosure of the invention, although the structure illustrated in FIG. 2 is not illustrated to scale.

[0070] In one aspect, the hydrogen gas purifier cell (50) illustrated in FIG. 2 may have a first MEA (24) substantially identical to that of the purifier cell (10), that is, having a first anode (28), a first electrolyte (30), and a first cathode (32) to at least partially purify the first gas stream (12) and produce a second gas stream (38) having a hydrogen gas content (34) and a non-hydrogen gas content (36) in substantially the same manner as the purifier cell (10) illustrated in FIG. 1. As is common in the art, at least a portion of the input or the first gas stream (12) may not be diffused through the anode (28) and may be removed into a gas stream (13), such as an "exhaust gas stream," for example. Additionally, the hydrogen gas purifier cell (50) may have a substantially identical second MEA (26) having a second anode (40), a second electrolyte (42), and a second cathode (44) to at least partially purify the gas stream (38) to produce a third gas stream (52) having a hydrogen gas content (54) and a non-hydrogen gas content (56). However, according to the aspect of the invention illustrated in FIG. 2, the hydrogen gas purifier cell (50) comprises at least one exhaust gas stream or displaced gas stream (58) having a non-hydrogen gas content (60) and a hydrogen gas content (62). It is recognized that the non-hydrogen gas content (60) and hydrogen gas content (62) of the exhaust gas stream (58) may be substantially the same as the non-hydrogen gas content (36) and hydrogen gas content (34) of the second gas stream (38).

[0071] In one aspect, to improve the distribution of the gas stream to the electrode surface, one or more gas diffusion layers (GDL) and / or flow field inserts not shown in FIG. 2 may be disposed within the cell (50). For example, the cell (50) may include a GDL and / or flow field inserts associated with a first anode (28), a first cathode (32), a second anode (40) and / or a second cathode (44).

[0072] According to this aspect, after the first gas stream (12) is processed by the first MEA (24) to produce a second gas stream (38) having a hydrogen gas content (34) and a non-hydrogen gas content (36), at least a portion of the gas stream (38) is removed through the gas stream (58). Removing the gas stream (58) from the gas stream (38) produces a modified or intermediate gas stream (64) having a hydrogen gas content (66) and a non-hydrogen gas content (68). It is recognized that the non-hydrogen gas content (68) and hydrogen gas content (66) of the modified gas stream (64) may be substantially the same as the non-hydrogen gas content (36) and hydrogen gas content (34) of the second gas stream (38). According to an aspect of the present invention, removing the gas stream (58) reduces the partial pressure of the non-hydrogen gas content (68) in the modified gas stream (64), and this reduction reduces the partial pressure gradient of the non-hydrogen gas content (58) across the second MEA (26), which reduces the passage of the non-hydrogen gas content (68) through the second MEA (26) into the third gas stream (52). Accordingly, according to an aspect of the present invention, the non-hydrogen gas content (56) of the third gas stream (52) is reduced.

[0073] The removal of the gas stream (58) having a non-hydrogen content (60) can be carried out by various means. In one aspect, the gas stream (58) can be removed by simply venting at least a portion of the second gas stream (38), such as venting through the inherent gap between the first MEA (24) and the second MEA (26), for example, through the inherent space or void between the surfaces of the first cathode (32) and the second anode (40). In another aspect, the gas stream (58) can be removed by providing a path, channel, or groove, for example, a radial or transverse channel or groove on the mating surface of the first cathode (32), the mating surface of the second anode (40), or both the mating surface of the first cathode (32) and the mating surface of the second anode (40). In another aspect, the gas stream (58) can be removed through a flow field insert located between the junction surface of the GDL and / or the first cathode (32) and the junction surface of the second anode (40). As is known in the art, the GDL is generally a porous material such as carbon paper through which the gas stream (58) can pass. In another aspect, the gas stream (58) can be removed by providing one or more spacers between the junction surface of the first cathode (32) and the junction surface of the second anode (40) to provide a path for the gas stream (58). In one aspect, a vacuum source may be introduced to draw at least a portion of the second gas stream (38) through the gas stream (58).

[0074] According to another aspect of the invention, after a first gas stream (12) is processed by a first MEA (24) to produce a second gas stream (38) having a hydrogen gas content (34) and a non-hydrogen gas content (36), at least some hydrogen gas may be introduced into the gas stream (38). As illustrated in FIG. 2, in one aspect, hydrogen gas may be introduced into the second gas stream (38) through a gas stream (59) (indicated by a phantom in FIG. 2) to replace the hydrogen gas (62) lost from the second gas stream (38) through the gas stream (58) and produce a modified gas stream (64). However, in one aspect, the gas stream (38) may be a high-purity hydrogen gas having a higher purity than, for example, the hydrogen content (14) of the first gas stream (12); in another aspect, the gas stream (59) may be a hydrogen gas-containing stream having at least some hydrogen gas content, but may have a non-hydrogen gas content.

[0075] For example, the introduction of a hydrogen-containing gas stream (59), which is a "supplementary gas stream," may be carried out with or without removing the gas stream (58). The introduction of the gas stream (59) into the gas stream (38) may be carried out in one or more convenient ways, for example, by introducing the hydrogen gas-containing stream (59) through a gas-permeable electrolyte (42) driven by a hydrogen gas partial pressure gradient, or through a gas-permeable first cathode (32), through a gas-permeable GDL and / or flow field insert, or through a channel of the first cathode (32), a channel of the second anode (40), or a channel of both the first cathode (32) and the second anode (40). Any channel that can be provided to the hydrogen gas-containing stream (59) may be located on one or both of the opposing surfaces of the first cathode (32) and the second anode (40), i.e., the spatial surface occupied by the second gas stream (38). In one aspect, the supplementary hydrogen gas stream (59) may include at least a portion of the third gas stream (52) having a third hydrogen content (54). For example, at least a portion of the third gas stream (52) may be introduced into the second gas stream (38) by diffusion through the second electrolyte (42), as indicated by the dashed line by the gas stream (59A) in FIG. 2. This diffusion through the second electrolyte (42) may be referred to as "back diffusion" through the second electrolyte (42) of at least a portion of the third gas stream (52) having a third hydrogen content (54), which is intended to provide at least a portion of the supplementary gas stream (59) to the second gas stream (38) or the modified gas stream (64). The supplementary gas stream (59) may be provided by one or more of these mechanisms.

[0076] According to an aspect of the invention, the third hydrogen gas content (54) of the third gas stream (52) is greater than the first hydrogen gas content (14) and the second hydrogen gas content (34); and the third impurity gas content (56) is less than the first impurity gas content (16) and the second impurity gas content (36). However, typically, the third gas stream (52) may have a purity greater than the purity of the first gas stream (12) on a "dry basis." For example, in one aspect, the purity of the third hydrogen gas content (54) may be at least 99.99 percent by volume, or at least 99.999 (5 9) percent by volume, or 99.9999 (6 9) percent by volume. According to another aspect of the invention, the purity of the third gas stream (52) may be expressed on a basis of the third impurity gas content (56). For example, in one aspect, the third impurity gas content (56) may be an impurity gas of up to 100 ppm. In another aspect of the invention, the generated third impurity gas content (56) may be up to 20 ppm, or up to 10 ppm, or up to 5 ppm, or up to 2 ppm, or up to 1 ppm. In another aspect of the invention, the third impurity gas content (56) of the generated hydrogen gas is It can be up to 750 ppb (i.e., up to 0.750 ppm); or up to 500 ppb; or up to 200 ppb; or even up to 100 ppb. As is known in the art, these impurity contents of the generated hydrogen gas are generally "dry standards."

[0077] FIG. 3 is a schematic elevation view of a hydrogen purifier stack assembly (80) having a hydrogen gas purifier cell (82) having, for example, the hydrogen gas purifier cell (10) or cell (50) disclosed herein, disposed between opposing electrically conductive but gas-impermeable layers or plates (84 and 86) and electrically conductive layers or bus bars (88 and 90) according to one aspect of the present invention. The electrically conductive but gas-impermeable layers or plates (84 and 86) may be referred to as "bipolar plates" as is known in the art, because the plates (84 and 86) may generally include passages or channels adapted to introduce or remove gas from the cell (82). The electrically conductive layers or bus bars (88 and 90) may also be referred to as "current collectors." As described, in one aspect, the cell (82) may include at least two MEAs, namely a first MEA (92) and at least a second MEA (94). However, according to an aspect of the invention, the cell (82) may include three or more MEAs (92, 94); or, for example, five or more MEAs (92, 94) placed between the bus bars (88 and 90). In one aspect, at least 10 MEAs (92, 94) may be placed between the bus bars (88 and 90).

[0078] In one aspect, the hydrogen gas purifier cell (82) may be referred to as a "double membrane electrode assembly" or "DMEA". The first MEA (92) comprises a first anode (96), a first electrolyte (98), and a first cathode (90). The first anode (96) may be similar, if not identical, to the first anode (28) disclosed herein; the first electrolyte (98) may be similar, if not identical, to the first electrolyte (30) disclosed herein; and the first cathode (90) may be similar, if not identical, to the first cathode (32) disclosed herein. The second MEA (94) comprises a second anode (102), a second electrolyte (104), and a second cathode (106). The second anode (102) may be similar, if not identical, to the second anode (40) disclosed herein. The second electrolyte (104) may be similar, if not identical, to the second electrolyte (42) disclosed herein. The second cathode (106) may be similar, if not identical, to the second cathode (44) disclosed herein.

[0079] The electrically conductive and gas-impermeable layer or plate (or bipolar plate) (84 and 86) can generally be made of a corrosion-resistant or non-oxidizing material due to the electrochemical properties of the cell (82). While it is thought that an electrically conductive, substantially gas-impermeable, and substantially corrosion-resistant material, such as a metal, could be used in the aspect of the invention for the plates (84 and 86), generally the plates (84 and 86) can be made of a graphite-containing material that is electrically conductive, substantially gas-impermeable, and substantially corrosion-resistant. For example, the plates (84 and 86) can be made of a material containing graphite powder and resin. In one aspect, the bipolar plates (84 and 86) can be made of a non-metallic material, such as plastic, into which electrically conductive inserts and / or particles are placed to provide the desired conductivity.

[0080] In one aspect, it is thought that the bipolar plates (84 and 86) may include at least a semipermeable portion to allow fluid permeability required for, for example, heat management and / or moisture management.

[0081] According to one aspect of the present invention, the electrically conductive current collectors (88 and 90) may have relatively high conductivity compared to, for example, the plates (84 and 86). In one aspect, the current collectors (88 and 90) may be plated, for example, gold or silver plated to improve conductivity. For example, the current collectors (88 and 90) may comprise a stainless steel plate, an aluminum plate, or a copper plate that may be plated with gold or silver.

[0082] According to an aspect of the present invention, as illustrated in FIG. 3, a first gas stream (108) containing hydrogen gas (H2) and non-hydrogen gas disclosed herein may be introduced into a first anode (96), wherein at least a portion of the hydrogen gas (H2) is hydrogen ions (H2) according to Equation 1. + ) and electrons (e-) are oxidized. The first gas stream (108) may be introduced into the first anode (96) by any conventional means, for example, through the passages and / or channels of the bipolar plate (84). For example, as shown in FIG. 3, the first gas stream (108) may be introduced into the first anode (96) through a plurality of lateral passages (110) communicating with a plurality of longitudinal passages or channels (112) discharged onto the first anode (96). The first anode (96) may include a GDL and / or flow field insert (not shown in FIG. 3), for example, a carbonaceous type GDL, to improve the distribution of the first gas stream (108) across the surface of the first anode (96).

[0083] Once introduced into the anode (96), the reaction and fluid flow described in relation to FIGS. 1 and 2 are generated within the MEA (92 and 94); specifically, a second gas stream (114) (not shown in FIG. 3) from the first cathode (100) and a third gas stream (116) from the second cathode (106) are generated according to aspects of the invention. As disclosed herein, the second anode (102) receives the second gas stream (114) (again, not shown in FIG. 3). In one aspect, the second anode (102) may include or be accompanied by a GDL and / or flow field insert (not shown in FIG. 3), for example, a carbonaceous type GDL, to improve the distribution of the second gas stream (114) across the surface of the second anode (102). The third gas stream (116) may be collected from the second cathode (106) by conventional means. For example, as illustrated in FIG. 3, the third gas stream (116) may be removed from the second cathode (106) with or without passing through a gas diffusion layer (not shown) via a plurality of longitudinal passages or a plurality of lateral passages (118) communicating with a plurality of channels (120) fluidly communicating with the second cathode (106). The plurality of lateral passages (118) may include a plurality of substantially parallel passages or a plurality of serpentine passages in the bipolar plate (86). As is known in the art, the parallel or serpentine passages of the bipolar plate (86) may fluidly communicate with one or more manifolds, e.g., vertical or longitudinal manifolds, and one or more manifolds may fluidly communicate with one or more ports for introducing, discharging, or redirecting the gas stream.

[0084] According to an aspect of the invention, the third gas stream (116) may contain a greater hydrogen gas (H2) content and a lower non-hydrogen gas content than the first gas stream (108). For example, as disclosed herein, the non-hydrogen gas content of the third gas stream (116) may have a non-hydrogen gas of up to 100 ppm, or up to 20 ppm, or up to 10 ppm, or up to 5 ppm, or up to 2 ppm, or up to 1 ppm, or even up to 500 ppb on a "dry basis." Additionally, the third gas stream (116) may generally have a higher pressure than the first gas stream (108), but in another aspect, the third gas stream (116) may have a lower pressure than the first gas stream (108).

[0085] A schematic detail of the interface between the first cathode (100) and the second anode (102) according to one aspect of the present invention is shown in FIG. 3a. FIG. 3a is a detail of a part of the hydrogen purifier stack assembly (80) shown in FIG. 3, identified by detail 3A shown in FIG. 3. As shown in FIG. 3a, a second gas stream (114) having a hydrogen gas content (34) (see FIG. 1 and 2) and a non-hydrogen gas content (36) exits the first cathode (100) and enters the space (101) between the junction surface of the first cathode (100) and the second anode (102). A space, void, or interstitial space (101) generally exists between the first cathode (100) and the second anode (102) due to imperfections in the junction surfaces of the first cathode (100) and the second anode (102), and among other things, manufacturing imperfections and / or tolerances. This space or void (101) may be minute, but generally exists between the junction surfaces of the first cathode (100) and the second anode (102) and other junction electrodes disclosed herein, and may provide a path for a gas stream, for example, for the removal and / or introduction of a gas stream. According to an aspect of the invention, a second gas stream (114) enters through direct contact or through the space (101) generally in contact with the second anode (102), and according to an aspect of the invention described herein, catalytic oxidation of the hydrogen gas content (34) in the second gas stream (114) occurs. In one aspect, the GDL (105) is positioned between the first cathode (100) and the second anode (102) as shown in FIG. 3b to facilitate or enhance the distribution of the second gas stream (114) across the surface of the second anode (102).In another aspect, a gas distribution or flow field insert with or without a GDL may be placed between the first cathode (100) and the second anode (102) (or between any electrodes disclosed herein) as indicated by the GDL (105) in FIG. 3b to facilitate or enhance the distribution of the second gas stream (114) over the surface of the second anode (102). The flow field insert may be an electrically conductive, porous, or perforated plate, e.g., a porous or perforated metal plate, or a screen-type insert, e.g., a metal screen-type insert, and is positioned and adapted to provide at least some gas distribution over the surface of the second anode (102). The flow field insert disclosed herein may also include a channel or passage to enable the introduction or removal of a gas stream from or to an adjacent electrode.

[0086] As disclosed herein, the gas purifier cell (82) may include the hydrogen gas purifier cell (10) disclosed and described for FIG. 1 or the hydrogen gas purifier cell (50) disclosed and described for FIG. 2. The detailed drawings shown in FIG. 3a and 3b also illustrate this aspect of the invention. Specifically, if the gas purifier cell (82) of FIG. 3 includes the purifier cell (10) as shown in FIG. 3a, almost all of the second gas stream (114) leaving the first cathode (100) passes directly to the second anode (102) (with or without GDL (105) and / or flow field insert) for subsequent catalytic oxidation, for example, through direct contact or through space (101), as disclosed herein.

[0087] In an aspect of the invention in which the gas purifier cell (82) of FIG. 3 comprises the purifier cell (50), at least a portion of the second gas stream (114) leaving the first cathode (100) is removed as a gas stream (58) as shown in FIG. 3a and 3b (see FIG. 2). According to this aspect, the removed gas stream (58) may contain at least some non-hydrogen gas, where, upon removal, the remaining modified gas stream has a lower partial pressure for the non-hydrogen gas. The lower partial pressure of the non-hydrogen gas is less likely to be delivered through the second electrolyte (104) and to the output or the third gas stream (116) (see FIG. 3). As illustrated in FIG. 3a, the removed or vented gas stream (58) may pass through the space (101) and / or, as illustrated in FIG. 3b, the removed or vented gas stream (58) may pass through the GDL (105) and / or the flow field insert.

[0088] As also illustrated in FIGS. 3a and 3b, in one aspect, a hydrogen-containing gas stream (59 and / or 59A) (indicated by dashed lines in FIGS. 3a and 3b) may be introduced into the second gas stream (114) with or without removing the gas stream (58). For example, as disclosed herein, the hydrogen-containing gas stream (59 and / or 59A) may be provided to enhance the hydrogen gas content of the second gas stream (114) introduced into the second anode (102), and may be provided, for example, to enhance the hydrogen content of the third gas stream (116) (see FIG. 3), i.e., the output stream (116), and / or to replace at least a portion of the hydrogen gas content removed from the gas stream (58). As illustrated in FIG. 3a and 3b, introducing a hydrogen-containing gas stream (59 and / or 59A) into space (101) can be performed with or in the presence of a GDL (105), and, for example, as illustrated in FIG. 3b, the hydrogen-containing gas stream (59) can be introduced through a gas-permeable GDL (105) and / or a flow field insert.

[0089] FIG. 4 is a schematic elevation view of a hydrogen purifier stack (130) having a plurality of hydrogen purifier cells (132A to 132N), having, for example, two or more hydrogen purifier cells (10) shown in FIG. 1 and / or two or more hydrogen cells (50) shown in FIG. 2, according to one aspect of the invention. According to an aspect of the invention, “N” is the number of purifier cells that may be included in the hydrogen purifier stack (130) according to an aspect of the invention. Specifically, N may be in the range of 1 to 1,000 cells, but generally may be in the range of 40 to 100 cells, for example, 80 cells.

[0090] According to this aspect of the invention, each hydrogen purifier cell (132A-132N) comprises a dual MEA (DMEA) separated by an electrically conductive and gas-impermeable layer or plate (134A-134N+1), for example, a "bipolar plate," as disclosed herein. The layer or plate (134A-134N+1) may be similar to and have the same characteristics as the layer or plate (84 and 86) shown and described in connection with FIG. 3. For example, the layer or plate (134A-134N+1) may have one or more lateral passages and a plurality of axial passages or channels, for example, flow distribution passages, which are adapted and positioned to introduce gas flow into the hydrogen purifier cell (132A-132N) and / or remove gas flow from the hydrogen purifier cell (132A-132N). According to an aspect of the invention, some plates (134A-134N+1), for example, the plate (134B) shown in FIG. 4, may include a separate passage, for example, adapted and positioned to remove a gas stream from the second cathode of the DMEA (132A) and also to introduce a gas stream from the first anode of the DMEA (132B). In contrast, the terminal plate (134A) may include a passage adapted and positioned to introduce a gas stream only to the first anode of the DMEA (132A), and the terminal plate (134N+1) may include a passage adapted and positioned to remove a gas flow only to the second cathode of the DMEA (132N). In one aspect, the terminal plate (134A) and / or the terminal plate (134N+1) may not have a passage, that is, may not have a passage.

[0091] According to an aspect of the invention, as disclosed herein, a reduction reaction associated with a cathode according to Equation 2 may provide electrons (e-) for an oxidation reaction associated with an anode according to Equation 1, for example, a prior or earlier anode of the stack. In one aspect, the flow of these electrons (e-) in a hydrogen purifier stack (130) causes the DMEA of the hydrogen purifier stack (130) to be electrically serial. However, to facilitate the description and disclosure of this aspect of the invention, the flow of electrons (e-) from the second anode to the first cathode in the hydrogen purifier stack (130) and the flow of electrons (e-) from the first anode to the second cathode, for example, the flow of neighboring cells are omitted in FIG. 4.

[0092] The hydrogen purifier stack (130) also includes opposing bus bars or current collectors (136 and 138) and end plates (137 and 139) (indicated by dashed lines in FIG. 4). The current collectors (136 and 138) may be similar in design, size, and structure to the current collectors (88 and 90) illustrated and disclosed in relation to FIG. 3. As is known in the art, the end plates (137 and 139) may be relatively thick metal plates that function to help compress the stack (130), for example, through a plurality of mechanical fasteners (not illustrated) extending between the end plates (137 and 139). For example, the end plates (137 and 139) may be associated with a plurality of threaded bolts having threaded nuts that compress the stack (130) between the plates (137 and 139) when the bolts are tightened.

[0093] As illustrated in FIG. 4, a plurality of input or first gas streams (140A-140N) having hydrogen gas (H2) content and non-hydrogen gas content may be introduced into the DMEA (132A-132N) through the inlet and flow distribution passage of the plate (134A-134N). As illustrated in FIG. 4, the first gas streams (140A-140N) may be provided, for example, through one or more gas supply manifolds (141) (indicated by dashed lines in FIG. 4), for example, through a common gas supply manifold. Also, as illustrated in FIG. 4, a plurality of discharge or third gas streams (142A-142N) may be removed from the DMEA (132A-132N), for example, through the flow extraction passage and outlet in the plate (134A-134N). As illustrated in FIG. 4, the third gas streams (142A-142N) may be discharged, for example, through one or more gas collection manifolds (143) (indicated by dashed lines in FIG. 4), for example, a common gas collection manifold. As disclosed herein, a plurality of output or third gas streams (142A-142N) each have a higher hydrogen gas (H2) content and a lower non-hydrogen gas content than a plurality of input gas streams (140A-140N). For example, as disclosed herein, the non-hydrogen gas content of the third gas streams (142A-N) may have a non-hydrogen gas of up to 100 ppm, or up to 20 ppm, or up to 10 ppm, or up to 5 ppm, or up to 2 ppm, or up to 1 ppm, or even up to 500 ppb "on a dry basis." Or even up to 500 ppb "on a dry basis." According to an aspect of the present invention, each of the gas stream flows from an input flow (140A-140N) to an output flow (142A-142N) may flow in parallel through a DMEA (132A-132N), for example, from one or more gas supply manifolds (141) to one or more gas collection manifolds (143).

[0094] For ease of description and disclosure of the invention, although not illustrated in FIG. 4, according to an aspect of the invention, a hydrogen purifier stack (130) generally comprises a plurality of anode exhaust ports, passages and / or manifolds so as to allow excess raw gas from streams (140A to 140N) to be discharged from the hydrogen purifier stack (130).

[0095] Also, as illustrated in FIG. 4, the hydrogen purifier stack (130) can be driven by a voltage (ΔV) and a current (I) between current collectors (136 and 138). The voltage (ΔV) may be provided externally, for example, by one or more DC power supplies, a local electrical grid, a fuel cell, a photovoltaic cell, and / or a wind turbine; and / or internally, for example, from the electrochemical potential and reactions occurring in the DMEA (132A-132N) of the stack (130). In one aspect, the voltage (ΔV) may be regulated to adjust the current passing through the stack (130). A higher current can enhance the chemical reactions within the stack (130) and increase the rate of hydrogen gas production. The amount of amperes required to enhance the output of this aspect of the invention will depend, among other things, on the size of the purifier and the number of cells in the purifier.

[0096] As also illustrated in FIG. 4, according to one aspect of the invention, one or more DMEAs (132A-132N) of a hydrogen purifier stack (130) may comprise a purifier cell (50) illustrated and described with respect to FIG. 2. That is, in one aspect, one or more DMEAs (132A-132N), for example, all DMEAs (132A-132N), may be adapted to remove at least a portion of a gas stream, such as the second gas stream (38) illustrated in FIG. 2, which is evolved at the first cathode of the DMEAs (132A-132N). Removing at least a portion of the gas stream from the second gas stream of the DMEAs (132A-132N) is indicated by gas streams (144A-144N) (indicated by dashed lines) in FIG. 4. The gas streams (144A-144N) in FIG. 4 correspond to the gas stream (58) in FIG. 2. As disclosed herein, according to one aspect of the invention, the removal of a gas stream (144A-144N) having at least some non-hydrogen gas content reduces the partial pressure of the non-hydrogen gas introduced into the second anode of the DMEA (132A-132N), thereby reducing the passage of the non-hydrogen gas through the second anode. According to one aspect, the gas stream (144A-144N) may be discharged from the hydrogen purifier stack (130) through the discharge passage of the hydrogen purifier stack (130), for example, a discharge gas manifold (not shown in FIG. 4).

[0097] Additionally, since a portion of the gas flow stream (144A-144N) (dash line) in FIG. 4 may contain some hydrogen gas content, in one aspect, at least some hydrogen gas is introduced into the second gas stream of DMEA (132A-132N) (i.e., the second gas stream (38) shown in FIG. 2) to replenish at least some of the lost hydrogen gas and improve the content of the hydrogen gas introduced into the second anode of DMEA (132A-132N). By replenishing the lost hydrogen gas through the gas flow stream (144A-144N), an aspect of the invention can improve the hydrogen content of the hydrogen gas produced by the hydrogen purifier stack (130). The introduction of at least some hydrogen gas into the second gas stream of DMEA (132A-132N) is indicated by the gas stream (146A-146N) (dash line) in FIG. 4. According to one aspect, the gas stream (146A-146N) can be introduced into the hydrogen purifier stack (130) through a passage of the hydrogen purifier stack (130), for example, a gas manifold (not shown in FIG. 4).

[0098] FIG. 5 is a schematic diagram of a hydrogen gas purifier cell (150) according to an additional aspect of the present invention. According to this aspect, the purifier cell (150) may have many features of the purifier cell (10) and the purifier cell (50) disclosed herein. Specifically, the purifier cell (150) comprises a DMEA (152) arranged to receive an input or first gas stream (154) having a first hydrogen gas content (156) and a first non-hydrogen gas content (158), and produces an output or third gas stream (160) having a third hydrogen gas content (162) and a third non-hydrogen gas content (164) having a third non-hydrogen gas content (164) and a first hydrogen gas content (158). As is common in the art, at least a portion of the input or first gas stream (154) may not be oxidized at the anode (166) but may be removed as a gas stream (155), such as an "exhaust gas stream." Typically, the exhaust stream (155) may be captured and sent, for example, through a channel, manifold, or port for further processing or disposed of as necessary.

[0099] In other words, the output or third gas stream (160) generally has a higher pressure than the input or first gas stream (154), but this pressure may be lower than the pressure of the first gas stream (154). However, according to this aspect of the invention, the DMEA (152) of the purifier cell (150) comprises only three electrodes, wherein the second electrode performs the dual function of the first cathode and the second anode as disclosed herein.

[0100] Specifically, as illustrated in FIG. 5, the DMEA (152) of the purifier cell (150) comprises a first anode (166), a first electrolyte (168), a first cathode / second anode (or "dual electrode") (170), a second electrolyte (172), and a second cathode (174). In a manner similar to the components and operation of the cell (10) and cell (50) disclosed herein, the first anode (166) may have all the features of the first anode disclosed herein; the first electrolyte (168) and the second electrolyte (172) may have all the features of the electrolyte disclosed herein; and the second cathode (174) may have all the features of the second cathode disclosed herein.

[0101] Additionally, the dual electrode (170) of the cell (150) may have all the features and characteristics of the anode or cathode disclosed herein, such as, for example, electrical conductivity, gas permeability, and catalytic properties. However, according to this aspect of the invention, the dual electrode (170) is a hydrogen ion (H) delivered through the first electrolyte (168) according to Equation 2 + ) electron(e - First, it is reduced to ) to produce hydrogen gas (H2), and then the hydrogen gas (H2) is oxidized according to Equation 1 to produce hydrogen ions (H + ) and electrons (e - It performs a dual function of generating ). In one aspect, electrons (e) generated from the oxidation of hydrogen gas (H2) at the dual electrode (170) - ) hydrogen ions (H) from the dual electrode (170) + The electrons consumed in the reduction of ) (e - It can be a source of ). These electrons (e) within the dual electrode (170) of DMEA (152). - The internal transfer of ) is represented by an electronic loop (176) indicated by a dashed line in FIG. 5. According to an aspect of the invention, one or more cells (150) may be used for the cells (132A-132N) of the stack (130) shown in FIG. 4.

[0102] According to one aspect of the present invention, an exhaust gas stream (gas stream (58) of FIG. 2) may be removed from the dual electrode (170) of the cell (150) and / or a supplementary gas stream (gas stream (59 and / or 59A) of FIG. 2) may be introduced into the dual electrode (170) of the cell (150). As shown in FIG. 5, the gas stream (178) may be removed through the dual electrode (170), for example, through a gas permeable structure of the dual electrode (170), thereby reducing the partial pressure of the non-hydrogen gas passing through the first electrode (168) as disclosed herein. Additionally, whether or not the gas stream (178) is removed, a supplementary hydrogen (H2) gas-containing gas stream (180) (indicated by a dashed line in FIG. 5) is introduced into the dual electrode (170), for example, through the gas-permeable structure of the dual electrode (170), to replace or enhance the hydrogen gas (H2) content of the gas stream introduced into the second electrolyte (172) as disclosed herein. As in another aspect of the invention, the supplementary hydrogen (H2) gas-containing gas stream (180) may be introduced into the dual electrode (170) by "reverse-diffusion" at least a portion of the gas stream (160) back into the dual electrode (170) through the second electrode (172).

[0103] In one aspect, gas streams and / or hydrogen ions (H₂) on the electrode surface + To improve the distribution of ), one or more gas diffusion layers (GDL) not shown in FIG. 5 and / or flow field inserts as described in relation to FIG. 3b may be located within the cell (150). For example, the cell (150) may include a GDL and / or flow field inserts associated with a first anode (166), a dual electrode (170), and / or a second cathode (174).

[0104] As in another aspect of the invention, even with only three electrodes (166, 170 and 174), the third hydrogen gas content (162) of the third gas stream (160) of the hydrogen purifier cell (150) is greater than the first hydrogen gas content (156); and the third impurity gas content (164) is less than the first impurity gas content (158). For example, the third gas stream (160) may have a purity greater than the purity of the first hydrogen gas content (156) of the first gas stream (154) on a "dry basis." For example, in one aspect, the purity of the third gas stream (160) may be at least 99.99 percent hydrogen by volume, at least 99.999 (5 9) percent by volume, or 99.9999 (6 9) percent by volume. According to another aspect of the present invention, the purity of the third gas stream (160) may be expressed based on the third impurity gas content (164). For example, in one aspect, the third impurity gas content (164) may be an impurity gas of up to 100 ppm. In another aspect of the present invention, the generated third impurity gas content (164) may be up to 20 ppm, or up to 10 ppm, or up to 5 ppm, or up to 2 ppm, or up to 1 ppm. In another aspect of the present invention, the third impurity gas content (164) of the generated hydrogen gas is It can be up to 750 ppb (i.e., up to 0.750 ppm), up to 500 ppb, up to 200 ppb, or even up to 100 ppb. As is known in the art, these impurity contents of the generated hydrogen gas are generally "dry standards."

[0105] Additionally, according to an aspect of the present invention, the resulting gas stream, i.e., the third gas stream (160) of FIG. 5, has a higher hydrogen gas content (162) and a lower impurity gas content (164), which can generally be provided at a higher pressure than the pressure of the feed or the first gas stream (154). For example, according to an aspect of the present invention, if the first gas stream (154) can have a pressure of up to 1 psig, the third gas stream (160) can have a pressure of at least 150 psig. In one aspect, the pressure of the third gas stream (160) can be at least 120 psig, or at least 200 psig, or even at least 10,000 [10 thousand] psig. In another aspect of the invention, the pressure of the third gas stream (160) may not be higher than the pressure of the feed or the first gas stream (154); in one aspect, the pressure of the third gas stream (160) may be lower than the pressure of the first gas stream (154).

[0106] FIG. 6 is a schematic diagram of a hydrogen gas purifier system (200) having one or more hydrogen purifiers (202) having one or more hydrogen purifier stacks (130) as shown in FIG. 4, according to one aspect of the invention. One or more hydrogen purifier stacks (130) may include one or more of any hydrogen purifier cells disclosed herein, for example, one or more cells (10), one or more cells (50) and / or one or more cells (150), or a combination thereof. One or more hydrogen purifier stacks (130) may be accommodated by end plates (204 and 206) similar to, for example, end plates (137 and 139) as shown in FIG. 4.

[0107] As illustrated in FIG. 6, a hydrogen gas purifier system (200) comprises a source of hydrogen-containing gas (208) operatively connected to one or more hydrogen purifiers (202) through one or more conduits or pipes (210). The source of hydrogen-containing gas (208) may be a storage tank, another gas purifier (202), one or more fuel cells, or one of various industrial processes. As disclosed herein, the source of hydrogen-containing gas (208) generally comprises at least some non-hydrogen or impurity gases such as nitrogen (N2), argon (Ar), carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), and / or oxygen (O2). As illustrated in FIG. 6, the flow gas from the source of hydrogen-containing gas (208) may be regulated by one or more flow control valves (212), for example, a manual valve or an automatic valve controlled by a suitable control system (not shown), and / or a pressure regulator (213). In one aspect, the hydrogen-containing gas (208) may be introduced into the system (200) under pressure by a gas pressurizing device (not shown), such as one or more blowers, fans, or compressors, for example. In another aspect, the hydrogen-containing gas (208) may be drawn into the system (200) by a gas depressurizing device or vacuum device (not shown), such as one or more blowers, fans, or compressors. For example, a vacuum source may be operatively connected to one or more conduits or pipes (214); to one or more discharge conduits (220); and / or one or more discharge conduits (221) of FIG. 6.

[0108] A hydrogen-containing gas is introduced from a source (208), and after undergoing appropriate oxidation and reduction as disclosed herein, the higher purity hydrogen gas is discharged from one or more hydrogen purifier stacks (202) into one or more conduits or pipes (214) and transferred to a storage or further treatment (216). For example, the further treatment (216) may be a dryer or desiccator for removing at least some water vapor and / or further purification, for example, if present, at least some trace impurities. The purification process may include a pressure shift adsorption (PSA) system, a temperature shift adsorption (TSA), a "getter" gas purifier, or other gas purifier system (200). In one aspect, the further treatment (216) may include a liquefier, for example, a cryo-cooler. As illustrated in FIG. 6, the gas flow from one or more hydrogen purifier stacks (202) can be controlled by one or more flow control valves (218), for example, a manual valve or an automatic valve controlled by a suitable control system (not shown).

[0109] As also shown in FIG. 6, the hydrogen-containing gas from the source (208) may generally have a pressure or a first pressure, and the gas introduced into the storage (216) after passing through one or more hydrogen purification stacks (202) may generally have a higher pressure or a third or output pressure (P2) greater than the first pressure (P1), as disclosed herein. The pressure (P2) may be one of the output pressures disclosed herein. In one aspect, the pressure (P2) is For example, the hydrogen-containing gas (208) may include a pressure lower than the pressure (P1) when it is drawn into the system (200) by vacuum.

[0110] As also shown in FIG. 6, in one aspect, one or more hydrogen purifier stacks (202) may comprise one or more purifier cells (50) (disclosed and described with respect to FIG. 2) having an exhaust gas stream or a displaced gas stream (58) and possibly a hydrogen-containing gas stream (59). As shown in FIG. 6, a gas purifier system (200) comprises one or more exhaust conduits (220) for removing the gas stream (58) (Fig. 2) and one or more exhaust conduits (221) for removing anode exhaust gas (e.g., the anode gas stream (13) shown in FIG. 1) from one or more hydrogen purifier stacks (202), and the exhaust gas stream in the conduit (220) and / or the exhaust gas stream in the conduit (221) may be sent to other processing, storage, or disposal (222). Other treatments of the gas stream within the conduits (220 and 221) may include purification, for example, among other things, through another system (200); venting to the atmosphere; combustion through a "flare"; or other treatments. As shown in FIG. 6, the flow of exhaust gas through the conduit (220) from one or more hydrogen purifier stacks (202) may be regulated by one or more flow control valves (224), for example, a manual valve or an automatic valve controlled by a suitable control system (not shown). In one aspect, at least a portion of the exhaust gas stream (stream (58) in FIG. 2) may be introduced into a purifier (200), such as the purifier (200) shown in FIG. 6 or another purifier (200), to recover and / or purify all hydrogen gas from the exhaust gas, for example, in the conduit (220). For example, as illustrated in FIG. 6, at least a portion of the gas discharged from the conduit (220) (stream (58) in FIG. 2) may be transferred to the input conduit (210) through the conduit or pipe (223) (illustrated by the dashed line in FIG. 6). The flow in the conduit (223) may include appropriate flow control and / or pressure control (not illustrated) as disclosed herein.

[0111] In one aspect, one or more purifier cells (50) receive a hydrogen-containing "replenishment" gas stream (59) (e.g., see FIG. 2) from a source (226), such as a discharge conduit (214) of this system or another system (200) or another hydrogen gas source. The above can be supplied through the conduit or pipe (228). The flow of "replenishment" gas through the one or more conduits (228) to one or more hydrogen purifier stacks (202) can be regulated by one or more flow control valves (230), for example, a manual valve or an automatic valve controlled by a suitable control system (not shown). In one aspect, the flow of "replenishment" gas into the cells of one or more hydrogen purifier stacks (202) can be regulated to control or "tune" the purity of the hydrogen gas produced and delivered, for example, to a storage or further processing (216). For example, the flow of "replenishment" gas can be regulated by controlling the purity of the produced hydrogen gas through one or more flow control valves (230); by regulating the pressure within one or more stacks (202) (for example, detected by a pressure sensor (236)); or by introducing a flow control orifice (for example, into the conduit (228); Among other methods, the “reverse diffusion” of hydrogen gas through the membrane in the cell of the stack (202) can be controlled. In one aspect, the flow of supplemental gas (stream (59) in FIG. 2) may not be supplied from the outside as shown in FIG. 6, but may also be supplied and routed internally in the stack (130), for example, from one or more cells (50) (see FIG. 2) to one or more cells (50), and the flow may be regulated and controlled based on flow and / or pressure.

[0112] According to one aspect of the present invention, the temperature of one or more hydrogen purifier stacks (130) of a gas purifier system (200) may be regulated and controlled, in particular, to optimize the purification performance of DMEA of the stack (130) and / or to prevent overheating of the stack (130). For example, in one aspect, the temperature of the stack (130) may be maintained at least 30°C, but is generally maintained in the range of 50°C to 80°C. It is understood that lowering the operating temperature of the electrolyte in the cell of the stack (130) to, for example, 45°C to 55°C can improve the purity of the generated hydrogen gas while requiring more reasonable power consumption. In one aspect, as shown in FIG. 6, the temperature of one or more hydrogen purifier stacks (130) may be monitored and regulated by one or more temperature sensors (232). The temperature of one or more hydrogen purifier stacks (130) detected by a temperature sensor (232) may be controlled by one or more heating or cooling circuits that are regulated and controlled by a suitable control system (not shown). The heating or cooling circuits of one or more hydrogen purifier stacks (130) may include one or more passages of hydrogen purifier stacks (130) through which a heating or cooling fluid may pass to regulate the temperature of one or more hydrogen purifier stacks (130).

[0113] According to one aspect of the present invention, the pressure of one or more hydrogen purifier stacks (130), the gas pressure from the source (208), and / or the exhaust gas pressure of the gas purifier system (200) may be regulated and controlled, in particular, to optimize the performance of the reaction within the DMEA of the stack (130). For example, in one aspect, the pressure of the hydrogen gas generated by one or more stacks (130) may be monitored and regulated by one or more pressure sensors (234). In some aspects, it is understood that the pressure of the hydrogen gas generated in the system (200) may affect the purity of the generated hydrogen gas. The pressure of the generated hydrogen gas detected by the pressure sensors (234) may be regulated and controlled by an appropriate control system (not shown).

[0114] Additionally, in one aspect, the pressure of one or more stacks (130) may be regulated and controlled to improve the performance, e.g., efficiency of the DMEA of the stacks (130). In one aspect, the pressure of the first cathode and / or second anode of one or more hydrogen purifier stacks (130) may be regulated and controlled to improve the performance, e.g. efficiency of the DMEA of the stacks (130). In one aspect, as illustrated in FIG. 6, the pressure of one or more stacks (130), e.g., the pressure of the first cathode and / or second anode, may be monitored and regulated by one or more pressure sensors (236). The pressure of one or more hydrogen purifier stacks (130) detected by the pressure sensors (236) may be controlled by a suitable control system (not shown).

[0115] FIG. 7 is a schematic diagram of a water electrolytic cell (250) according to another aspect of the present invention. According to this aspect, the water electrolytic cell (250) comprises an electrochemical cell for electrolyzing water to produce hydrogen gas, specifically hydrogen gas with less undesirable impurity gas such as oxygen (O2). As illustrated in FIG. 7, the water electrolytic cell (250) is positioned and adapted to receive a feed or a first fluid stream (252) containing water. The first fluid stream (252) may contain liquid water and / or gaseous water (i.e., steam). (It should be understood that any reference to "fluid" herein may refer to a liquid fluid, a gaseous fluid, or both a liquid fluid and a gaseous fluid.) According to an aspect of the present invention, the cell (250) is adapted to produce a hydrogen gas stream or a third gas stream (254) with little or no gas impurities, containing little or no oxygen gas. The third gas stream (254) may be referred to as an exhaust gas stream (254).

[0116] As schematically illustrated in FIG. 7, the water electrolytic cell (250) comprises a multilayer structure having components, for example, an anode and a cathode, which generally have a thin planar or thin layered structure in a manner similar to the hydrogen gas purifier cell disclosed herein, and the structure illustrated in FIG. 7 may include a side view or a cross-sectional view of the water electrolytic cell (250) drawn to facilitate the disclosure of the present invention, although the structure is not drawn to scale.

[0117] According to an aspect of the present invention, to provide a desired hydrogen gas (254), a water electrolytic cell (250) generally comprises a first MEA (256) and at least one second MEA (258). The first MEA (256) comprises a first anode (260), which may generally be fluid permeable, specifically water or gas permeable, in a manner similar to other anodes disclosed herein, wherein at least a portion of the water of the first fluid stream (252) may pass into the anode (260), for example, in the axial direction indicated by the arrow of the first fluid stream (252). Additionally, the anode (260) comprises at least some catalyst, for example, at least some platinum group metal-containing or iridium-containing catalyst, which, for example according to Equation 3, gaseous oxygen (O2), hydrogen ions (H₂). + ) and electronic(e - It can improve the oxidation of water to ).

[0118] Equation 3

[0119] In one aspect, to improve the distribution of the first fluid stream (252) over the surface of the anode (260), an electrically conductive gas diffusion layer (GDL) and / or flow field insert not shown in FIG. 7 may be positioned between the first fluid stream (252) and the anode (260), for example, the GDL may be applied over the surface of the anode (260) contacted by the first fluid stream (252). In one aspect, the GDL used for the cell (250) or the GDL layer used in any aspect disclosed herein may be a metal-based GDL, for example, a platinum-coated titanium GDL or an equivalent.

[0120] Due to the permeability of the anode (260), water (H2O) passes through the anode (260), and due to the electrical conductivity of the anode (260), electrons (e -) is conducted out from the anode (260), and according to an aspect of the invention, hydrogen ions (H+) generated at the anode (260) are introduced into the electrolyte (262). The electrolyte (262) may be similar to other electrolytes disclosed herein, for example, the electrolyte (262) may be an acidic electrolyte.

[0121] As is common in the art, at least a portion of the input or first fluid stream (252) may be removed as a fluid stream (264), e.g., an "exhaust gas stream," without diffusing through the anode (260). Typically, the exhaust stream (264) may be captured and sent, e.g., through channels, manifolds, and ports for further processing or disposed of as necessary.

[0122] The electrolyte (262) or the first electrolyte (262) contains at least some hydrogen ions (H + It is positioned and adapted to receive and transmit ). Because the anode (260) is very close to the electrolyte (262), hydrogen ions (H + ) passes from the anode (260) to the electrolyte (262). The first electrolyte (262) includes a barrier between the first anode (260) and the electrode (266). The first electrolyte (262) contains hydrogen ions (H + It may include any material or substance capable of transmitting, for example, hydrogen ions (H+), i.e., protons, from the first anode (260) to the electrode (266). That is, in one aspect, the electrolyte (262) and any electrolyte disclosed herein may be referred to as a "proton-conducting material" while substantially blocking the flow of gas. The first electrolyte (262) may generally be acidic and may be, for example, an acidic polymer containing perfluorosulfonic acid (PFSA). In one aspect, the electrolyte (262) is Nafion from The Chemours Company in Wilmington, Delaware. TMIt may be a membrane sold under the trademark or an equivalent. In another aspect, the electrolyte (262) may include one or more of the following acids: phosphoric acid [H3PO4], sulfuric acid [H2SO4], or other hydrogen ions (H + ) Conductive acid. In one aspect, the first electrolyte (262) may include a proton exchange membrane (PEM) as is known in the art.

[0123] As is known in the art, the electrode (266), which may be referred to as a "cathode" (266) or a first cathode (266), is a hydrogen ion (H) delivered by the first electrolyte (262). + It is positioned to receive at least a portion of ). Similar to other cathodes disclosed herein, the first cathode (266) is fluid-permeable and generally contains a catalyst, e.g., a platinum group-containing catalyst, which, as is known in the art, according to Equation 4, at least a portion of electrons (e - Hydrogen ions (H) passing through the ) and the first electrolyte (262) + It is adapted to enhance at least some of the reactions (i.e., reduction).

[0124] Equation 4.

[0125] The resulting, or "evolved" hydrogen gas (H2) (268), or the second fluid stream (268) containing hydrogen gas (H2), is delivered through the gas-permeable first cathode (266) as indicated by the gas stream (268) or the second fluid stream (268) in FIG. 7.

[0126] In one aspect, to improve the distribution of hydrogen gas (H2) on the surface of the second anode (270), a gas diffusion layer (GDL) and / or flow field insert not shown in FIG. 7 may be positioned between the first cathode (266) and the second anode (270), and, for example, the GDL and / or flow field insert may be applied over the surface of the second anode (270).

[0127] As illustrated in FIG. 7, according to an aspect of the invention, a second fluid stream (268) containing hydrogen gas (H2) may subsequently be introduced into a second MEA (258), specifically the electrode (270) or the second anode (270) of the second MEA (258). In the schematic diagram of the electrolytic cell (250) illustrated in FIG. 7, the first MEA (256) is shown spaced apart from the second MEA (258) to facilitate the description and disclosure of the invention. However, according to an aspect of the invention, the gap between the first MEA (256) and the second MEA (270) may be minimized, for example, when the surface of the first cathode (266) may be adjacent to or in contact with the surface of the second anode (270). However, in one aspect, for example, at least some gap of 0.1 millimeter [mm] to 0.5 mm may exist between the surface of the first cathode (266) and the surface of the second anode (270).

[0128] According to an aspect of the present invention, unlike conventional technology, a second fluid stream (268) having hydrogen gas (H2) can be introduced into a second MEA (258) without removing or extracting the second fluid stream (268) from the electrolytic cell (250). In other words, while a portion of the second fluid stream (268) may undesirably "escape" from the electrolytic cell (250), according to one aspect of the present invention, almost all of the second fluid stream (268) generated at the first cathode (266) is received by the second anode (270). For example, in one aspect, the second fluid stream (268) can be allowed to pass from the first cathode (266) of the MEA (256) to the second anode (270) of the MEA (258) without passing outside, for example, the electrolytic cell (250), and without any intervening handling or processing. In one aspect, the evolved hydrogen gas (H2) formed at the first cathode (266) substantially immediately produces hydrogen ions (H2) at the second anode (270). + It can be oxidized to ). In one aspect, the second fluid stream (268) can be made to pass directly from the first cathode (266) of the MEA (258) of the electrolytic cell (250) to the second anode (270) of the MEA (258) without passing outside the electrolytic cell (250) before reaching, for example, the second cathode (270).

[0129] The second anode (270) is positioned to be in contact with a second fluid stream (268) having hydrogen gas (H2). The second anode (270) of the second MEA (258) may be similar, if not identical, to the first anode (260) of the MEA (256). The second anode (270) may be hydrogen gas permeable, where at least some of the hydrogen gas of the second fluid stream (268) may pass through the second anode (40), for example, axially, as indicated by the arrow of the second fluid stream (268). Additionally, the second anode (270) may contain hydrogen ions (H2) of the hydrogen gas, as indicated by Equation 1 reconstructed below. + It includes at least some catalysts capable of enhancing oxidation to ), for example, at least some platinum-containing catalysts.

[0130] Equation 1.

[0131] In one aspect, to improve the distribution of the second fluid stream (268) on the surface of the second anode (270), a gas diffusion layer or GDL and / or flow field insert not shown in FIG. 7 may be positioned between the second fluid stream (268) and the second anode (270), for example, the GDL and / or flow field insert may be applied over the surface of the second anode (270) that is contacted by the second fluid stream (268).

[0132] According to an aspect of the present invention, a catalyst included in the second anode (270) promotes or enhances the oxidation of hydrogen gas in the second fluid stream (268) so as to produce hydrogen ions (H) according to Equation 1. + ) and electrons (e - ) produces or generates. In one aspect, electrons (e) generated at the second anode (270). - ) is directed back to the first cathode (266) as indicated by the arrow (272) in FIG. 7, and hydrogen ions (H) at the first cathode (266) according to Equation 4+ The electrons (e) used to reduce ) to hydrogen (H2) - ) middle At least a portion can be supplied. Due to the permeability of the second anode (270), at least a portion of the hydrogen gas (H2) generated at the second anode (270) can pass through the second anode (270) and, according to an aspect of the invention, is introduced into or comes into contact with the electrolyte (274).

[0133] The electrolyte (274) of the MEA (258), or the second electrolyte (274), is hydrogen ions (H) received from the second anode (270). + It is positioned and adapted to receive and transmit at least a portion of ). The second electrolyte (274) includes a gas barrier between the second anode (270) and the cathode (276). The second electrolyte (274) may be similar to, if not substantially identical to, the first electrolyte (262), and hydrogen ions (H + Capable of transmitting, for example, hydrogen ions (H + ), that is, may include any material or substance capable of selectively delivering protons from the second anode (270) to the cathode (276). In other words, as mentioned in relation to the first electrolyte (262), in one aspect the second electrolyte (274) may be referred to as a "proton-conducting material." The second electrolyte (274) may typically be acidic and may contain, for example, one or more of the acids identified herein. However, in one aspect, the second electrolyte (274) may include a PEM, as is known in the art.

[0134] The electrode (276) or cathode (276) is a hydrogen ion (H) delivered by the second electrolyte (274). +It is positioned to receive at least some of ). Similar to the second anode (266), the second cathode (276) is generally permeable and contains a catalyst, e.g., a platinum-containing catalyst, which, according to Equation 2 reproduced below, receives at least some electrons (e - Using ) at least some hydrogen ions (H + It is adapted to improve the reduction of ).

[0135] Equation 2.

[0136] The resulting, or "evolved" hydrogen gas (H2) or a third fluid stream (254) containing hydrogen gas (H2) is generated by the electrolysis cell (250).

[0137] In one aspect, hydrogen ions (H + To improve the distribution on the surface of the second cathode (276) of the apparatus, a gas diffusion layer (GDL) or flow field insert not shown in FIG. 7 may be positioned between the second electrolyte (274) and the second cathode (276), for example, the GDL and / or flow field insert may be applied over the surface of the second cathode (276). In one aspect, the GDL or flow field insert not shown in FIG. 7 may be positioned adjacent to the downstream surface of the second cathode (276) to improve the removal of the third fluid stream (254).

[0138] According to an aspect of the present invention, the third fluid stream (254) of the electrolysis cell (250) may contain hydrogen gas (H2) that has little to no generally undesirable impurity gas, for example, little to no oxygen gas.

[0139] According to an aspect of the present invention, by passing a second fluid stream (268) from the first anode (266) of the MEA (256) to the second cathode (270) of the second MEA (258) in an electrolysis cell (250), a more efficient device can be provided that provides purer hydrogen gas than the prior art. Among other things, for example, by passing the second fluid stream (268) directly from the first cathode (266) to the second anode (270), the content of impurities, for example, oxygen gas impurities, in the third fluid stream (254) is minimized.

[0140] FIG. 8 is a schematic diagram of a water electrolytic cell (300) according to another aspect of the present invention. According to this aspect, the electrolytic cell (300) may have many features of the electrolytic cell (250), but the electrolytic cell (300) further includes at least one gas discharge or release between the MEAs. A reduction in the content of the second fluid stream is considered to reduce the partial pressure of the non-hydrogen gas between the MEAs, e.g., the partial pressure of oxygen, and thus reduce the driving force of the partial pressure gradient of the undesirable non-hydrogen gas through the second MEAs. Also in an additional aspect, since some of the desirable hydrogen gas is lost when a portion of the second fluid stream is removed, at least some hydrogen gas may be introduced between the MEAs to function as "replenishing" hydrogen gas for the hydrogen gas that may be lost while removing a portion of the second fluid stream.

[0141] As illustrated in FIG. 8, a water electrolytic cell (300) is positioned and adapted to receive a feed or a first fluid stream (302) into the electrolytic cell (300). According to an aspect of the invention, the cell (300) is adapted to generate a hydrogen gas stream or a third fluid stream (304) that is almost free of gas impurities and contains little or no oxygen gas. The third gas stream (254) may be referred to as an exhaust gas stream (254). Similar to the electrolytic cell (250) illustrated in FIG. 8, it comprises a multilayer structure having components, such as an anode and a cathode, which generally have a thin planar or thin layered structure, wherein the structure illustrated in FIG. 8 may include a side view or cross-sectional view of the electrolytic cell (300) drawn to facilitate the disclosure of the invention, although the structure illustrated in FIG. 8 is not drawn to scale.

[0142] In one aspect, the electrolytic cell (300) illustrated in FIG. 8 may have a first MEA (306) substantially identical to that of the electrolytic cell (250), having a first anode (308), a first electrolyte (310), and a first cathode (312), so as to oxidize and reduce a first fluid stream (302) to produce a second fluid stream (314) containing hydrogen gas (H2) in substantially the same manner as the MEA (256) of the electrolytic cell (250) illustrated in FIG. 7. As is common in the art, at least a portion of the input or first fluid stream (302) may not be oxidized at the first anode (308) but may be removed into a fluid stream (303), such as an "exhaust fluid stream." Additionally, the electrolytic cell (300) may have a substantially identical second MEA (316) having a second anode (318), a second electrolyte (320), and a second cathode (322) to produce a third fluid stream (304) containing hydrogen gas (H2) in a substantially identical manner to the electrolytic cell (250) shown in FIG. 7. However, according to the aspect of the invention shown in FIG. 8, the electrolytic cell (300) includes at least one exhaust gas stream or displaced gas stream (324) having hydrogen gas and a non-hydrogen gas such as oxygen.

[0143] In one aspect, to improve the distribution of the gas stream to the electrode surface, one or more gas diffusion layers (GDL) and / or gas distribution media not shown in FIG. 8 may be located within the electrolytic cell (300). For example, the electrolytic cell (300) may include a GDL and / or flow field insert associated with a first anode (308), a first cathode (312), a second anode (318) and / or a second cathode (322).

[0144] According to this aspect, a first fluid stream (302) is processed and passes through a first MEA (306) to produce a second fluid stream (314) having a hydrogen gas content and a non-hydrogen gas content (36), after which at least a portion of the second fluid stream (314) is removed through a fluid stream (324). Removing the fluid stream (324) from the fluid stream (314) produces a modified or intermediate fluid stream (326). According to an aspect of the invention, removing the fluid stream (324) reduces the partial pressure of the non-hydrogen gas in the modified fluid stream (326), and this reduction in partial pressure reduces the partial pressure gradient of the non-hydrogen gas content across the second MEA (316), which reduces the passage of the non-hydrogen gas through the second MEA (316) into the third fluid stream (304). Accordingly, according to an aspect of the present invention, the non-hydrogen gas content, e.g., oxygen gas content, of the third fluid stream (304) is reduced to provide a purer stream of hydrogen gas.

[0145] The removal of the fluid stream (324) can be carried out by various means. In one aspect, the fluid stream (324) can be removed, for example, by venting through an inherent gap between the first MEA (306) and the second MEA (316), for example, by simply venting at least a portion of the second fluid stream (314) through an inherent space or void between the surfaces of the first cathode (312) and the second anode (318). In another aspect, the fluid stream (324) can be removed by providing a path, channel, or groove, for example, a radial or transverse channel or groove on the bonding surface of the first cathode (312), the bonding surface of the second anode (318), or both the bonding surface of the first cathode (312) and the bonding surface of the second anode (318). In another aspect, the fluid stream (324) may be removed through a GDL and / or flow field insert located between the bonding surface of the first cathode (312) and the bonding surface of the second anode (318). As is known in the art, the GDL is generally a porous material such as carbon paper through which the gas stream (324) can pass. In another aspect, the fluid stream (324) may be removed by providing one or more spacers between the bonding surface of the first cathode (312) and the bonding surface of the second anode (318) to provide a path for the fluid stream (324). In one aspect, a sub-atmospheric pressure source, namely a vacuum, may be introduced to draw at least a portion of the second fluid stream (314) through the fluid stream (324).

[0146] According to another aspect of the invention, after the first fluid stream (302) is processed and passes through the first MEA (306) to produce a second fluid stream (314), at least some hydrogen gas may be introduced into the second fluid stream (314). As illustrated in FIG. 8, in one aspect, hydrogen gas may be introduced into the second fluid stream (314) through a fluid stream (328) (indicated by a dashed line in FIG. 8) to replace the hydrogen gas lost from the second fluid stream (314) through the fluid stream (324) and to produce a modified fluid stream (326). In one aspect, the fluid stream (328) may be a high-purity hydrogen gas having a higher purity than, for example, the hydrogen content of at least the first fluid stream (302); in another aspect, the fluid stream (328) may be a hydrogen gas-containing stream having at least some hydrogen gas content, but may have a non-hydrogen gas content.

[0147] For example, introducing a hydrogen-containing gas stream (328), which is a "supplementary gas stream," into the electrolysis cell (300) may be carried out with or without removing the fluid stream (324). Introducing the fluid stream (328) into the second fluid stream (314) may be carried out in one or more convenient ways, for example, by introducing the hydrogen gas-containing stream (328) through an electrolyte (310) that may be gas-permeable and driven by a hydrogen gas partial pressure gradient, through a gas-permeable first cathode (312), through a gas-permeable GDL and / or flow field insert, or through a channel of the first cathode (312), through a channel of the second anode (318), or through channels of both the first cathode (312) and the second anode (318). Any channel that can be provided for the hydrogen gas-containing stream (328) may be located on one or both of the opposing surfaces of the first cathode (312) and the second anode (318).

[0148] In one aspect, the supplementary hydrogen gas stream (328) may comprise at least a portion of the third fluid stream (304) having a hydrogen content. For example, at least a portion of the third fluid stream (304) may be introduced into the second fluid stream (314) by diffusion through the second electrolyte (320), as indicated by the dashed line by the gas stream (328A) in FIG. 8. This diffusion through the second electrolyte (320) may be referred to as "reverse diffusion" of at least a portion of the third fluid stream (304) having at least some hydrogen gas (H2). The supplementary gas stream (328) may be provided by one or more of these sources or mechanisms.

[0149] In another aspect of the invention, the three-electrode cell (150) illustrated in FIG. 5 may also function as an electrolytic cell. For example, as illustrated in FIG. 5, the DMEA (152) of the purifier cell (150) comprises a first anode (166), a first electrolyte (168), a first cathode / second anode (or "dual electrode") (170), a second electrolyte (172), and a second cathode (174). In a manner similar to the components and operation of the electrolytic cell (250) illustrated in FIG. 7, in the electrolytic cell (150) illustrated in FIG. 5, the anode (166) may have all the features of the first anode disclosed herein; the first electrolyte (168) and the second electrolyte (172) may have all the features of the electrolyte disclosed herein; and the second cathode (174) may have all the features of the second cathode disclosed herein. In this aspect of the invention, the components and fluid flow of the electrolytic cell (150) illustrated in FIG. 5 may have all the functions and characteristics of the purifier cell (150) disclosed herein, including oxidation at the first anode (166) according to Equation 3 and reduction at the second cathode (174) according to Equation 4. However, in the case of the electrolytic cell (150), the first fluid stream (154) of FIG. 5 may include liquid water and / or gaseous water (i.e., steam). (It should be understood that any reference to "fluid" herein may refer to liquid fluid, gaseous fluid, or both liquid fluid and gaseous fluid.) According to an aspect of the invention, the electrolytic cell (150) of FIG. 5 may be adapted to produce a hydrogen gas stream or a third fluid stream (160) that contains little or no oxygen gas and little or no gaseous impurities.

[0150] According to one aspect of the present invention, one or more water electrolysis cells (250 and 300) may be provided to generate high-purity hydrogen gas. In one aspect, a water electrolysis stack having one or more electrolysis cells (250 and / or 300) may be provided, for example, a water electrolysis stack similar to the hydrogen purifier stack (130) shown in FIG. 4. Also, in one aspect, a water electrolyzer system having one or more electrolysis cell stacks having one or more electrolysis cells (250 and / or 300) may be provided, for example, a water electrolysis similar to the hydrogen purifier system (200) shown in FIG. 6.

[0151] As disclosed above, embodiments of the present invention provide improved hydrogen purification and water electrolysis capable of meeting and exceeding the hydrogen gas purity required by hydrogen gas users in various aspects. Aspects of the present invention utilize a unique combination of membrane electrode assemblies (MEAs) or dual MEAs (DMEAs) that have been shown to provide the required improved hydrogen gas purity.

[0152] The terms used herein are used solely to describe specific embodiments and are not intended to limit the disclosure. The singular forms "a," "an," and "the" used herein are intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising" as used herein designate the presence of the specified features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups.

[0153] All means or steps plus corresponding structures, materials, acts, and equivalents of functional elements in the claims below are intended to include all structures, materials, or acts for performing a function in combination with other specifically claimed elements. The description of this disclosure is presented for illustrative and illustrative purposes but is not intended to be exhaustive or limited to the disclosed form. Many modifications and changes will be apparent to a person skilled in the art without departing from the scope and spirit of the disclosure. The embodiments have been selected and described to best illustrate the principles and practical applications of the disclosure and to enable a person skilled in the art to understand the disclosure for various embodiments through various modifications suitable for the specific use being considered.

[0154] Although various aspects of the invention have been described and depicted herein, alternative aspects may be practiced by those skilled in the art to achieve the same purpose. Accordingly, the appended claims are intended to encompass all alternative aspects within the true spirit and scope of the invention.

Claims

Claim 1 A method for reducing the impurity gas content of a gas stream (12) having a hydrogen gas content (14) and an impurity gas content (16), the method comprising: introducing a first gas stream (12) having a first hydrogen gas content and a first impurity gas content into a first anode (28) containing a catalyst; catalytically oxidizing at least a portion of the first hydrogen gas content in the first anode (28) to generate hydrogen ions and electrons; transferring at least a portion of the hydrogen ions through a first electrolyte (30) to a first cathode (32) containing a catalyst and diffusing at least a portion of the impurity gas content; and catalytically reducing at least a portion of the hydrogen ions transferred through the first electrolyte (30) in the first cathode (32) to generate a second gas stream (38) having a second hydrogen gas content (34) greater than the first hydrogen gas content and a second impurity gas content (36) less than the first impurity gas content. A method comprising the steps of: introducing the second gas stream (38) into a second anode (40) having a catalyst adjacent to the first cathode (32); catalytically oxidizing at least a portion of the second hydrogen gas content in the second gas stream (38) to generate hydrogen ions and electrons in the second anode (40); transferring at least a portion of the hydrogen ions generated in the second anode (40) to the second cathode (44) through a second electrolyte (42) and diffusing at least a portion of the second impurity gas content (36); and catalytically reducing at least a portion of the hydrogen ions transferred through the second electrolyte (42) in the second cathode (44) to generate a third gas stream (18, 52) having a third hydrogen gas content (54) greater than the first hydrogen gas content and a third impurity gas content (56) smaller than the first impurity gas content. Claim 2 The method of claim 1 further comprises the step of removing at least a portion of the second gas stream (38) to produce a modified gas stream (64) having a non-hydrogen gas partial pressure lower than the non-hydrogen gas partial pressure in the second gas stream. Claim 3 In paragraph 2, the step of introducing the second gas stream into the second anode includes the step of introducing the modified gas stream (64) into the second anode. Claim 4 A method according to claim 2 or 3, wherein the step of removing at least a portion of the second gas stream (38) comprises removing at least a portion of the second gas stream through a passage between the first electrolyte and the second electrolyte. Claim 5 A method according to paragraph 4, wherein the passage is located between the first cathode and the second anode. Claim 6 A method according to claim 5, wherein the passage located between the first cathode and the second anode comprises a void (101) between the bonding surfaces of the first cathode and the second anode. Claim 7 In claim 5, the step of removing at least a portion of the second gas stream (38) comprises removing at least a portion of the second gas stream through a gas diffusion layer (GDL) (105) disposed between the first cathode and the second anode. Claim 8 In claim 5, the step of removing at least a portion of the second gas stream comprises removing at least a portion of the second gas stream through at least one channel on the surface of at least one of the first cathode and the second anode. Claim 9 In any one of claims 1 to 3, the method further comprises the step of introducing some hydrogen gas (59) into the second gas stream. Claim 10 In claim 9, the step of introducing some hydrogen gas into the second gas stream is to replenish at least some hydrogen gas (59A) removed from the second gas stream. Claim 11 A method according to any one of claims 1 to 3, wherein the third hydrogen gas content is at least 99.999 percent hydrogen on a dry basis and by volume. Claim 12 A method according to any one of claims 1 to 3, wherein the third impurity gas content is a maximum of 10 ppm on a dry basis. Claim 13 A method for reducing the impurity gas content of a gas stream (12) having a hydrogen gas content (14) and an impurity gas content (16), the method comprises: introducing a first gas stream (12) having a first hydrogen gas content (14) and a first impurity gas content (16) into a first membrane electrode assembly (MEA) (24) having a first anode (28), a first electrolyte (30), and a first cathode (32) containing a catalyst to produce a second gas stream (38) having a second hydrogen gas content (34) and a second impurity gas content (36); A method comprising the step of directly passing the second gas stream (38) through a second MEA (26) having a second anode (40), a second electrolyte (42), and a second cathode (44) adjacent to the first cathode (32), and containing a catalyst to produce a third gas stream (18, 52) having a third hydrogen gas content (20, 54) greater than the first hydrogen gas content and a third impurity gas content (22, 56) less than the first impurity gas content. Claim 14 In claim 13, the first MEA (24) and the second MEA (26) are placed in a hydrogen purification cell (10, 50, 150), and the step of passing the second gas stream directly through the second MEA (26) includes the step of passing the second gas stream through the second MEA while ensuring that the second gas stream does not leave the hydrogen purification cell. Claim 15 A method according to claim 13 or 14, further comprising the step of removing at least a portion of the second gas stream (38) to produce a modified second gas stream (64) having a reduced non-hydrogen gas partial pressure than the second gas stream. Claim 16 In paragraph 15, the method further comprises the step of introducing at least some hydrogen gas (59, 59A) into the second gas stream. Claim 17 A method for purifying hydrogen gas comprises the steps of: introducing a first gas stream (154) having a first hydrogen gas content (156) and a first impurity gas content (158) into an anode (166) containing a catalyst; catalytically oxidizing at least a portion of the first hydrogen gas content in the anode (166) to generate hydrogen ions and electrons; transferring at least a portion of the hydrogen ions generated in the anode to a dual electrode (170) through a first electrolyte (168); generating a second gas stream having a second hydrogen gas content in the dual electrode (170), and catalytically reducing at least a portion of the hydrogen ions transferred through the first electrolyte to generate hydrogen ions and electrons by catalytically oxidizing at least a portion of the second hydrogen gas content in the second gas stream; and transferring at least a portion of the hydrogen ions generated in the dual electrode to a cathode (174) through a second electrolyte (172). A method comprising the step of catalytically reducing at least some of the hydrogen ions delivered through the second electrolyte to produce a third gas stream (160) having a third hydrogen gas content (162) greater than the first hydrogen gas content and a third impurity gas content (164) less than the first impurity gas content at the cathode (174). Claim 18 In paragraph 17, the method further comprises the step of removing at least a portion of the second gas stream. Claim 19 In paragraph 18, the step of removing at least a portion of the second gas stream comprises removing at least a portion of the second gas stream through a gas diffusion layer. Claim 20 In claim 18, the dual electrode (170) comprises a gas-permeable electrode, and the step of removing at least a portion of the second gas stream comprises removing at least a portion of the second gas stream through the gas-permeable dual electrode. Claim 21 A method according to any one of claims 18 to 20, wherein the step of removing at least a portion of the second gas stream comprises removing at least a portion of the second gas stream through the second electrolyte. Claim 22 In any one of claims 17 to 20, the method further comprises the step of introducing at least some hydrogen gas (180) into the second gas stream. Claim 23 In claim 22, the step of introducing the at least partial hydrogen gas (180) into the second gas stream comprises the step of introducing the at least partial hydrogen gas into the second gas stream through a gas diffusion layer. Claim 24 In claim 22, the dual electrode (170) comprises a gas-permeable electrode, and the step of introducing the at least partial hydrogen gas (180) into the second gas stream comprises introducing the at least partial hydrogen gas into the second gas stream through the gas-permeable dual electrode. Claim 25 In claim 22, the step of introducing the at least partial hydrogen gas (180) into the second gas stream comprises the step of introducing the at least partial hydrogen gas into the second gas stream through the second electrolyte. Claim 26 A method according to any one of claims 17 to 20, wherein the third impurity gas content (164) contains up to 10 ppm of impurity gas on a dry basis. Claim 27 A method for electrolyzing water, wherein the method comprises: introducing a first H2O-containing fluid stream (252) into a first anode (260) containing a catalyst; catalytically oxidizing at least a portion of the H2O in the first H2O-containing fluid stream at the first anode (260) to produce oxygen gas, hydrogen ions, and electrons; transferring at least a portion of the hydrogen ions to a first cathode (266) containing a catalyst through a first electrolyte (262); catalytically reducing at least a portion of the hydrogen ions transferred through the first electrolyte at the first cathode (266) to produce a second gas stream having hydrogen gas; introducing the second gas stream having hydrogen gas into a second anode (270) having a catalyst; catalytically oxidizing at least a portion of the hydrogen gas in the second gas stream at the second anode (270) to produce hydrogen ions and electrons; and a second electrolyte (274). A method comprising the steps of: transferring at least some of the hydrogen ions generated at the second anode to the second cathode (276); and catalytically reducing at least some of the hydrogen ions transferred through the second electrolyte to produce a third gas stream (254) having hydrogen gas at the second cathode (276). Claim 28 In claim 27, the method further comprises the step of removing at least a portion of the second gas stream (268) to produce a modified gas stream having a non-hydrogen gas partial pressure lower than the non-hydrogen gas partial pressure in the second gas stream. Claim 29 In claim 28, the step of introducing the second gas stream (268) into the second anode (270) comprises the step of introducing the modified gas stream into the second anode. Claim 30 In claim 29, the step of removing at least a portion of the second gas stream (268) comprises removing at least a portion of the second gas stream through a passage between the first electrolyte and the second electrolyte. Claim 31 A method according to paragraph 30, wherein the passage is located between the first cathode and the second anode. Claim 32 A method according to claim 31, wherein the passage located between the first cathode and the second anode comprises a void between the bonding surfaces of the first cathode and the second anode. Claim 33 A method according to claim 31 or 32, wherein the step of removing at least a portion of the second gas stream comprises removing at least a portion of the second gas stream through a gas diffusion layer (GDL) disposed between the first cathode and the second anode. Claim 34 A method according to claim 31 or 32, wherein the step of removing at least a portion of the second gas stream comprises removing at least a portion of the second gas stream through at least one channel on the surface of at least one of the first cathode and the second anode. Claim 35 In any one of paragraphs 27 to 32, the method further comprises the step of introducing some hydrogen gas into the second gas stream (268). Claim 36 A method according to any one of claims 28 to 32, wherein the method further comprises the step of introducing some hydrogen gas into the second gas stream (268) to replenish at least some hydrogen gas removed from the second gas stream.

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