Apparatus, system and method for electrochemically purifying hydrogen

Abstract

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

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to pending U.S. patent application No. 17 / 934,341, filed on September 22, 2022, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] The present invention generally relates to electrochemical purification and / or compression of hydrogen gas. Specifically, aspects of the present invention include electrochemical cells, systems and methods that employ one or more membrane electrode assemblies (MEAs) in a single MEA cell to purify and / or compress hydrogen gas and avoid external processing of gas streams between individual MEA cells. Background Art Description of Related Technology

[0003] As is known in the art, high purity hydrogen (i.e., hydrogen having a hydrogen content greater than 99.99% by volume) has many uses. However, hydrogen is often found mixed with other undesirable gases, such as nitrogen, argon, carbon dioxide, oxygen, and carbon monoxide, etc. Therefore, there is a need in the art for improved methods of separating hydrogen from undesirable gases to provide hydrogen in a purer form.

[0004] Hydrogen purification is not easy to accomplish. Hydrogen is generally difficult to separate from other gases due to the relatively small size of hydrogen molecules and the flammability of hydrogen, etc. Existing means for purifying hydrogen from undesirable non-hydrogen gases include molecular sieves, membranes, palladium membranes, and electrochemical hydrogen pumps (EHP).

[0005] Molecular sieves separate hydrogen molecules by selective adsorption, preferentially retaining some molecules over others. However, in many cases, molecular sieve adsorption systems have an undesirable, insignificant effect on hydrogen purity. One such case is nitrogen (N 2 ) and hydrogen (H 2 ) separation.

[0006] Palladium selectively allows only hydrogen atoms to move through the metal, resulting in high-purity hydrogen. However, palladium is expensive, the process requires compressed gas, and high hydrogen recovery requires high pressures and / or large amounts of palladium.

[0007] Electrochemical hydrogen pumps (EHP) selectively extract hydrogen from a mixture of hydrogen and other gases (e.g., nitrogen and argon). However, typically, other undesirable gases diffuse through the pump's membrane and result in limited hydrogen purity. Therefore, multiple separate electrochemical hydrogen pumps can be used in series, each EHP having an associated housing, cell stack, feed conduit and exhaust conduit, and other separate hardware and control systems, in an attempt to purify the hydrogen gas stream twice, thereby increasing hydrogen purity. However, such a configuration requires multiple separate electrochemical pump unit stacks and multiple sets of electrochemical stack hardware connected together. This undesirably leads to an increase in system complexity and cost.

[0008] Another method of purifying hydrogen is to increase the membrane thickness in the electrochemical cell. However, increasing the membrane thickness is generally limited to reducing the diffusion of impurities through the membrane only in accordance with the thickness of the membrane. Other methods of purifying hydrogen require undesirable gas compression, undesirable multiple pumps, recover less hydrogen, consume more energy, and / or do not produce the high purity hydrogen required by today's hydrogen users (e.g., the semiconductor industry).

[0009] Therefore, there is a need in the art for improved hydrogen purification systems, methods, and apparatus. Summary of the invention

[0010] Embodiments of the present invention, in its various aspects, address this recognized need by providing improved hydrogen purification that meets and can exceed the hydrogen purity required for a variety of different applications. Aspects of the present invention employ a unique combination of a membrane electrode assembly (MEA) or "dual" MEA (DMEA) that has been demonstrated to provide the improved hydrogen purity required by today's users.

[0011] One embodiment of the present invention is a hydrogen purifier unit, which contains or includes a first membrane electrode assembly (MEA) and a second MEA. The first MEA includes: a first anode, the first anode is positioned to contact a first gas stream having a first hydrogen content and a first impurity gas content, the first anode contains a catalyst suitable for oxidizing at least some of the first hydrogen content to produce hydrogen ions and electrons, such as a catalyst containing a platinum group; a first electrolyte, such as an acidic electrolyte, the first electrolyte is positioned and suitable for receiving and transferring at least some of the hydrogen ions produced by the first anode; and a first cathode, the first cathode is positioned to receive at least some of the hydrogen ions transferred by the first electrolyte, the first cathode contains a catalyst suitable for reducing at least some of the hydrogen ions to produce a second gas stream, the 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. The second MEA comprises or includes: a second anode, which is positioned to receive a second gas flow from the first cathode of the first MEA, the second anode containing a catalyst suitable for oxidizing at least some of the second hydrogen content in the second gas flow to produce hydrogen ions and electrons; a second electrolyte, such as an acidic electrolyte, which is positioned and suitable for receiving and transferring at least some of the hydrogen ions produced by the second anode; and a second cathode, which is positioned to receive at least some of the hydrogen ions transferred from the second electrolyte of the second MEA, the second cathode containing a catalyst suitable for reducing at least some of the hydrogen ions and electrons to produce a third gas flow, the third gas flow having a third hydrogen content greater than the first hydrogen content and a third impurity gas content less than the first impurity gas content.

[0012] In one aspect, the purifier unit may also include at least one passage between the first electrolyte and the second electrolyte for discharging at least some of the second gas stream. For example, the at least one passage may be located between the first cathode and the second anode. In one aspect, the at least one passage located between the first cathode and the second anode may be included in a space or gap between the mating surfaces of the first cathode and the second anode. On the other hand, the purifier unit may also include a gas permeable layer or 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 some of the second gas stream. On the other hand, with or without the GDL, a gas distribution or flow field insert may be positioned between the first cathode and the second anode to facilitate or enhance the distribution of the second gas stream on the surface of the second anode. The flow field insert may be a conductive porous or perforated plate (e.g., a porous or perforated metal plate) or a screen-like insert (e.g., a metal screen-like insert) that is positioned and adapted to provide at least some gas distribution around the surface of the second anode. In another aspect, the at least one passage for exhausting at least some of the second gas stream can be at least one channel proximate to the first cathode, the second anode, or both.

[0013] On the other hand, the purifier unit may also include or include at least one passage between the first electrolyte and the second electrolyte for introducing a hydrogen-containing gas into the second gas stream. For example, the at least one passage may be located between the first cathode and the second anode. In one aspect, the at least one passage may be a space or gap between the mating surfaces of the first cathode and the second anode. In one aspect, the purifier unit may also include a gas permeable layer or gas diffusion layer (GDL) between the first cathode and the second anode, and the GDL may provide at least one passage for introducing a hydrogen-containing gas into the second gas stream. On the other hand, with or without the GDL, a gas distribution or flow field insert may be positioned between the first cathode and the second anode to facilitate or enhance the distribution of the second gas stream on the second anode surface. The flow field insert may be a porous or perforated plate (e.g., a porous or perforated metal plate) or a sieve insert (e.g., a metal sieve insert) positioned and adapted to provide at least some gas distribution around the surface of the second anode.

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

[0015] In one aspect, the first gas flow can have a first gas pressure and the third gas flow can have a third gas pressure, wherein the third gas pressure is greater than the first gas pressure. In other aspects, the third gas pressure can be less than the first gas pressure.

[0016] Another embodiment of the present invention is a hydrogen purification system, which contains or includes: at least one hydrogen purifier unit disclosed herein; and at least two electrically conductive plates, one of the at least two plates being mounted to a first end of the at least one hydrogen purifier unit, and one of the at least two plates being mounted to a second end of the at least one hydrogen purifier unit opposite to the first end. For example, in one aspect, the at least one hydrogen purifier unit can include a plurality of hydrogen purifier units, such as a hydrogen purifier unit stack.

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

[0018] In one aspect, the method may also include removing at least some of the second gas stream to produce a modified gas stream, the non-hydrogen gas partial pressure of the modified gas stream being less than the non-hydrogen gas partial pressure in the second gas stream. On the other hand, introducing the second gas stream into the second anode includes introducing the modified gas stream into the second anode. In one aspect, removing at least some of the second gas stream can be implemented by removing at least some of the second gas stream through a passage between the first electrolyte and the second electrolyte, for example, the passage can be located between the first cathode and the second anode. In one aspect, the passage for removing at least some of the second gas stream can be a space or gap between the mating surfaces of the first cathode and the second anode. On the other hand, removing at least some of the second gas stream can be implemented by removing at least some of the second gas stream through a gas diffusion layer (GDL) and / or a flow field insert located between the first cathode and the second anode. On the other hand, removing at least some of the second gas stream can be implemented by removing at least some of the second gas stream through at least one passage adjacent to the first cathode, the second cathode, or both.

[0019] On the other hand, the method can also include introducing some hydrogen into the second gas stream, such as a "make-up" gas stream. In one aspect, introducing some hydrogen into the second gas stream can make up for at least some of the hydrogen removed from the second gas stream. In one aspect, the make-up hydrogen stream can include at least some of the third gas stream having a third hydrogen content. For example, the third gas stream can be introduced into the second gas stream by diffusion through the second electrolyte. This diffusion through the second electrolyte can be referred to as "back diffusion" of at least some of the third gas stream having a third hydrogen content through the second electrolyte to the second gas stream.

[0020] In one aspect, by using the electrochemical cells and methods disclosed herein, the purified hydrogen produced, for example, the third impurity gas content, can be at least 100 times lower by volume than the impurity content of the input gas content (e.g., the first impurity gas content). In another aspect, the impurity gas content of the produced hydrogen can be at least 1,000 times, 10,000 times, 100,000 times, or even 1,000,000 times or less lower than the impurity content of the first hydrogen gas stream.

[0021] In one aspect, the impurity gas content of the hydrogen produced by any method, unit and system of the present invention, for example in the third gas stream, can be at most one hundred parts per million (100 ppm), that is, the third gas stream can contain at most 100 ppm of impurity gas. In other aspects of the present invention, the impurity gas content of the produced hydrogen can be at most 20 ppm, or at most 10 ppm, or at most 5 ppm, or at most 2 ppm, or at most 1 ppm. In other aspects of the present invention, the impurity gas content of the produced hydrogen can be at most 750 ppb (seven hundred and five parts per billion, i.e. at most 0.750 ppm), or at most 500 ppb, or at most 200 ppb, or even at most 100 ppb. As known in the art, these impurity contents of the produced hydrogen (e.g., a content 1000 times lower than the impurity gas content of the first gas stream, or an impurity gas content in ppm or ppb) are typically "on a dry basis". As is known in the art, "on a dry basis" means that there may be some water vapor present in the produced gas stream to be reduced or removed (eg, in a subsequent drying process).

[0022] Another embodiment of the present invention is a method for reducing the impurity gas content of a gas flow, the gas flow having a hydrogen content and an impurity gas content, the method comprising or including: introducing a first gas flow having a first hydrogen content and a first impurity gas content into a first membrane electrode assembly (MEA) to produce a second gas flow having a second hydrogen content and a second impurity gas content, the first MEA having a first anode containing a catalyst, a first electrolyte, and a first cathode containing a catalyst; and moving the second gas flow directly to a second MEA to produce a third gas flow, the second MEA having a second anode containing a catalyst, a second electrolyte, and a second cathode containing a catalyst, the third gas flow having a third hydrogen 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 can be positioned in a hydrogen purification unit, and moving the second gas flow directly to the second MEA can include moving the second gas flow directly to the second MEA without allowing the second gas flow to exit the hydrogen purification unit.

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

[0025] Another embodiment of the present invention is a hydrogen purifier unit, the hydrogen purifier unit comprising or including: a membrane electrode assembly (MEA). The membrane electrode assembly (MEA) includes: an anode positioned to contact a first gas stream having a first hydrogen content and a first impurity gas content, the anode containing a catalyst suitable for oxidizing at least some of the first hydrogen content to produce hydrogen ions and electrons; a first electrolyte positioned and suitable for receiving and transferring at least some of the hydrogen ions received from the anode; a dual electrode positioned to receive at least some of the hydrogen ions transferred through the first electrolyte, the dual cathode containing a catalyst suitable for reducing at least some of the hydrogen ions to produce a second gas stream having a second hydrogen content and oxidizing at least some of the second hydrogen content in the second gas stream to produce hydrogen ions and electrons; a second electrolyte positioned and suitable for receiving and transferring at least some of the hydrogen ions received from the dual electrodes; and a cathode positioned to receive at least some of the hydrogen ions transferred through the second electrolyte, the cathode containing a catalyst suitable for reducing at least some of the hydrogen ions to produce a third gas stream having a third hydrogen content greater than the first hydrogen content and a third impurity gas content less than the first impurity gas content.

[0026] In one aspect, the hydrogen purifier unit further comprises at least one passage for removing at least some of the second gas stream. For example, the at least one passage for removing at least some of the second gas stream can be the bi-electrode, such as the permeability of the bi-electrode; the gas permeable diffusion layer; and / or the second electrolyte.

[0027] In one aspect, the hydrogen purifier unit further comprises at least one passage for introducing at least some hydrogen into the second gas stream. For example, the at least one passage for introducing at least some hydrogen can be a bi-electrode, such as a permeability of the bi-electrode; a gas permeable diffusion layer; and / or a second electrolyte, such as via "backward diffusion".

[0028] Another embodiment of the present invention is a method for purifying hydrogen, which comprises or includes: introducing a first gas stream having a first hydrogen content and a first impurity gas content into an anode containing a catalyst; in the anode, catalytically oxidizing at least some of the first hydrogen content to produce hydrogen ions and electrons; transferring at least some of the hydrogen ions produced in the anode through a first electrolyte to a dual electrode; in the dual electrode, catalytically reducing at least some of the hydrogen ions transferred through the first electrolyte to produce a second gas stream having a second hydrogen content, and catalytically oxidizing at least some of the second hydrogen content in the second gas stream to produce hydrogen ions and electrons; transferring at least some of the hydrogen ions produced in the dual electrode to a cathode through a second electrolyte, and in the cathode, catalytically reducing at least some of the hydrogen ions transferred through the second electrolyte to produce a third gas stream, the third gas stream having a third hydrogen content greater than the first hydrogen content and a third impurity gas content less than the first impurity gas content.

[0029] In one aspect, the method can further include removing at least some of the second gas flow, for example, through at least one passage. For example, the at least one passage for removing at least some of the second gas flow can be a gas diffusion layer; a gas permeable dual electrode; and / or a second electrolyte, for example via "back diffusion".

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

[0031] Another embodiment of the present invention is a water electrolysis device unit, which includes or comprises: a first membrane electrode assembly (MEA) and a second MEA. The first MEA includes: a first anode, the first anode is positioned to contact a first H-containing 2 O, the first anode containing a first H 2 At least some of the H in the fluid stream of O 2O to produce oxygen, hydrogen ions and electrons; a first electrolyte, the first electrolyte is positioned and suitable for receiving and transferring at least some of the hydrogen ions produced by the first anode; and a first cathode, the first cathode is positioned to receive at least some of the hydrogen ions transferred through the first electrolyte, the first cathode containing a catalyst suitable for reducing at least some of the hydrogen ions to produce a second fluid stream containing hydrogen. The second MEA includes: a second anode, the second anode is positioned to receive a second fluid stream containing hydrogen from the first cathode of the first MEA, the second anode containing a catalyst suitable for oxidizing at least some of the hydrogen to produce hydrogen ions and electrons; a second electrolyte, the second electrolyte is positioned and suitable for receiving and transferring at least some of the hydrogen ions produced by the second anode; and a second cathode, the second cathode is positioned to receive at least some of the hydrogen ions transferred through the second electrolyte of the second MEA, the second cathode containing a catalyst suitable for reducing at least some of the hydrogen ions to produce a third fluid stream containing hydrogen.

[0032] In one aspect, the electrolyzer unit can also include at least one passage between the first electrolyte and the second electrolyte for discharging at least some of the second fluid flow. For example, the passage for discharging the second fluid flow can be located between the first cathode and the second anode. For example, the at least one passage between the first cathode and the second anode can be: a gap between mating surfaces of the first cathode and the second anode; and / or a gas diffusion layer (GDL) and / or a flow field insert between the first cathode and the second anode.

[0033] In another aspect, the water electrolyzer unit may further include at least one passage between the first electrolyte and the second electrolyte for introducing a hydrogen-containing gas into the second gas stream. For example, the passage for introducing hydrogen gas may be: a gap between the mating surfaces of the first cathode and the second anode; and / or a GDL and / or a 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 or including: 2 O is introduced into a first anode containing a catalyst; in the first anode, a first H-containing 2 At least some of the H in the fluid stream of O 2O to produce oxygen, hydrogen ions and electrons; transfer at least some of the hydrogen ions through the first electrolyte to a first cathode containing a catalyst; in the first cathode, catalytically reduce at least some of the hydrogen ions transferred through the first electrolyte to produce a second fluid stream having hydrogen; introduce the second fluid stream having hydrogen to a second anode having a catalyst; in the second anode, catalytically oxidize at least some of the hydrogen in the second fluid stream to produce hydrogen ions and electrons; transfer at least some of the hydrogen ions generated at the second anode to the second cathode through the second electrolyte; and in the second cathode, catalytically reduce at least some of the hydrogen ions transferred through the second electrolyte to produce a third fluid stream having hydrogen. According to various aspects of the present invention, a "fluid stream" may be a liquid stream, a gaseous stream and / or a liquid stream and a gaseous stream.

[0035] In one aspect, the method can further include removing at least some 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 in the second fluid stream. The method can further include introducing the modified fluid stream to a second anode.

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

[0037] Another embodiment of the present invention is a water electrolysis device unit, which includes or comprises: a membrane electrode assembly (MEA). The membrane electrode assembly (MEA) includes: an anode, the anode is positioned to contact a first H-containing 2 O, the anode containing a fluid stream suitable for oxidizing a first H 2 At least some of the H in the fluid stream of O 2 O to produce oxygen, hydrogen ions and electrons; a first electrolyte, the first electrolyte is positioned and suitable for receiving and transferring at least some of the hydrogen produced by the anode; a dual electrode, the dual electrode is positioned to receive at least some of the hydrogen ions transferred through the first electrolyte, the dual cathode contains a catalyst suitable for reducing at least some of the hydrogen ions to produce a second gas stream having a second hydrogen content and oxidizing at least some of the second hydrogen content in the second gas stream to produce hydrogen ions and electrons; a second electrolyte, the second electrolyte is positioned and suitable for receiving and transferring at least some of the hydrogen ions received from the dual electrodes; and a cathode, the cathode is positioned to receive at least some of the hydrogen ions transferred through the second electrolyte of the second MEA, the cathode containing a catalyst suitable for reducing at least some of the hydrogen ions to produce a third fluid stream containing hydrogen.

[0038] Another embodiment of the present invention is a method for electrolyzing water, the method comprising or including: 2 O is introduced into an anode containing a catalyst; in the anode, the first H-containing2 At least some of the H in the fluid stream of O 2 O to produce oxygen, hydrogen ions and electrons; transferring at least some of the hydrogen ions produced in the anode to the dual electrodes through the first electrolyte; in the dual electrodes, catalytically reducing at least some of the hydrogen ions transferred through the first electrolyte to produce a second fluid stream having a second hydrogen content, and catalytically oxidizing at least some of the second hydrogen content in the second gas stream to produce hydrogen ions and electrons; transferring at least some of the hydrogen ions produced in the dual electrodes to the cathode through the second electrolyte; and in the cathode, catalytically reducing at least some of the hydrogen ions transferred through the second electrolyte to produce a third fluid stream having hydrogen.

[0039] These and other aspects, features and advantages of the present invention will become apparent from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The subject matter of the present invention is particularly pointed out and expressly claimed in the claims at the end of this specification. The foregoing and other objects, features and advantages of the present invention will be readily understood from the following detailed description of the various aspects of the present invention in conjunction with the accompanying drawings, in which:

[0041] Figure 1 is a schematic illustration of a hydrogen purifier unit according to one aspect of the present invention.

[0042] Figure 2 is a schematic illustration of a hydrogen purifier unit according to another aspect of the present invention.

[0043] Figure 3 According to various aspects of the present invention, Figure 1 or Figure 2 A schematic elevation view of a hydrogen purifier stack assembly of a hydrogen purifier unit is shown.

[0044] Figure 3A Is Figure 3 The details shown in 3A are marked Figure 3 Detailed view of the hydrogen purifier stack assembly shown in .

[0045] Figure 3B According to another aspect of the present invention, it is similar to Figure 3A Detailed view of the .

[0046] Figure 4 According to one aspect of the present invention, Figure 1 and / or Figure 3 A schematic elevation view of a hydrogen purifier stack of multiple hydrogen purifier units is shown.

[0047] Figure 5is a schematic illustration of a hydrogen purifier unit according to another aspect of the present invention.

[0048] Figure 6 According to one aspect of the present invention, one or more Figure 4 A schematic illustration of a hydrogen purifier system showing a hydrogen purifier stack is shown.

[0049] Figure 7 is a schematic illustration of a water electrolysis device unit according to another aspect of the present invention.

[0050] Figure 8 is a schematic illustration of a water electrolysis device unit according to another aspect of the present invention. DETAILED DESCRIPTION

[0051] Figure 1 1 is a schematic diagram of a hydrogen purifier unit 10 according to one aspect of the present invention. According to this aspect, the purifier unit 10 is positioned and adapted to receive a hydrogen gas having at least some hydrogen content 14 (i.e., diatomic hydrogen, H 2 ) and at least some non-hydrogen gas 16, and produces a gas stream 18 having a reduced non-hydrogen gas content, i.e., a gas stream 18 having a purer hydrogen content. The non-hydrogen gas 16 may typically contain nitrogen (N 2 ), argon (Ar), carbon monoxide (CO), methane (CH 4 ), oxygen (O 2 ) and / or carbon dioxide (CO 2 ), and other gases, etc. According to one aspect of the present invention, the expression "non-hydrogen gas" may refer to a gas that is not diatomic hydrogen (H 2 ) gas. The gas stream 18 with reduced non-hydrogen gas content can be referred to as an exhaust gas stream 18 or a third gas stream 18. The third gas stream 18 can generally include an increased hydrogen content 20 and a reduced non-hydrogen gas content 22, for example, a higher purity hydrogen gas stream (such as having a non-hydrogen gas content of up to 100 ppm on a dry basis). In other aspects of the present invention, the non-hydrogen gas content 22 of the gas stream 18 can 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 non-hydrogen gas content in the gas stream 18, in various aspects of the present invention, the gas stream 18 can generally have an increased hydrogen content 20 (e.g., by volume percentage) and an increased hydrogen pressure, such as a pressure higher than the pressure of the feed gas stream 12. In one aspect, the pressure of the gas stream 18 can be less than the pressure of the gas stream 12. Since a desired function of the purifier unit 10 is to reduce or substantially eliminate the content of the non-hydrogen gas 16 , the non-hydrogen gas 16 may be referred to as an “impurity gas” 16 or a “first impurity gas” 16 .

[0052] like Figure 1 As schematically shown in FIG. 1 , the hydrogen purifier unit 10 generally comprises a multilayer structure having components (eg, an anode and a cathode having a thin planar or thin layer configuration), wherein Figure 1 The structures shown in the drawings may include side elevation views or transverse axial cross-section views of the purifier unit 10, which are not drawn to scale but are drawn to facilitate the disclosure of the present invention.

[0053] According to various aspects of the present invention, to provide the desired increased hydrogen content 20 and generally increased hydrogen pressure, the purifier unit 10 generally includes a first membrane electrode assembly (MEA) 24 and at least one second MEA 26. The first MEA 24 includes a first electrode 28, specifically a first "anode" 28, as referred to in the art. The anode 28 and any anodes disclosed herein can generally be gas permeable, specifically hydrogen permeable, wherein at least some of the hydrogen content 14 and at least some of the non-hydrogen gas content 16 in the first gas stream 12 can move through the anode 28 (e.g., in the axial direction indicated by the arrows of the first gas stream 12). In addition, the anode 28 and any anode or cathode disclosed herein include a conductive layer that can enhance the oxidation of hydrogen to hydrogen ions (H + ), for example, at least some platinum group metal-containing catalyst, such as a platinum-containing catalyst, although in some aspects, non-platinum group metal-containing catalysts can be used for anode 28 and any anode or cathode disclosed herein. As is known in the art, the platinum group metal-containing catalyst can be a catalyst containing at least some nickel (Ni), at least some palladium (Pa) and / or at least some platinum (Pt).

[0054] The first anode 28 is positioned to contact the first gas stream 12 having a first hydrogen content 14 and a first impurity gas content 16. The relative contents of the first hydrogen content 14 and the first impurity gas content 16 of the first gas stream 12 are in the range Figure 1 Schematically shown in FIG. 1 and schematically illustrated in the other figures by partially shading the arrows indicating the first gas flow 12. The gas flow arrows 12 (and Figure 1 Such partial shading of the gas flow arrows 38 and 18 in FIG. 1 is for illustration only and does not represent the actual relative gas contents of these gas flows in accordance with aspects of the present invention.

[0055] In one aspect, to enhance the distribution of the first gas stream 12 around the surface of the anode 28, Figure 1A conductive gas diffusion layer (GDL), not shown in the drawings, can be positioned between the first gas stream 12 and the anode 28, for example, the GDL can be applied to the surface of the anode 28 that is contacted by the first gas stream 12. In one aspect, the GDL used in the unit 10 or the GDL layer used in any aspect disclosed herein can be a carbon fiber type GDL, such as a GDL provided by SGL Carbon GmBH or its equivalent. On the other hand, with or without the GDL, a gas distribution or flow field insert (as disclosed herein) can be positioned above the anode 102 to promote or enhance the distribution of the first gas stream 12 on the surface of the anode 28.

[0056] According to various aspects of the present invention, the catalyst contained in the first anode 28 promotes or enhances the at least hydrogen (H) introduced into the anode 28. 2 ) to generate or produce hydrogen ions (H + ) and electron (e - ). H 2 =>2H + +2e - Equation 1. Due to the permeability of the anode 28, hydrogen (H 2 ) moves into the anode 28, and due to the conductivity of the anode 28, the electrons (e - ) are conducted away from the anode 28, and according to various aspects of the present invention, the hydrogen ions (H + ) are introduced into the electrolyte 30. As is known in the art, hydrogen ions (H + ) are protons. However, it is recognized in the art that at least some undesirable non-hydrogen gases 16 also move through the anode 28.

[0057] As is common in the art, at least some of the input or first gas stream 12 may not be oxidized at the anode 28, but rather removed as a gas stream 13 (e.g., an "exhaust gas stream"). Typically, the exhaust gas stream 13, which typically has less hydrogen content due to the hydrogen oxidation that occurs in the first anode 28, may be captured and directed (e.g., via channels, manifolds, and ports) for further processing or disposal as desired.

[0058] The electrolyte 30 or first electrolyte 30 is positioned and adapted to receive and transfer at least some of the hydrogen ions (H + Since the anode 28 is in close proximity to the electrolyte 30, the hydrogen ions (H + ) and non-hydrogen gas move from the anode 28 to the electrolyte 30. The first electrolyte 30 comprises a barrier between the first anode 28 and the electrode 32. The first electrolyte 30 may comprise a barrier capable of transporting hydrogen ions (H+ ) (e.g., selectively converting hydrogen ions (H + ) (i.e., protons) from the first anode 28 to the electrode 32). That is, in one aspect, the electrolyte 30 and any electrolyte disclosed herein can be referred to as a "proton conductive material" while substantially preventing the flow of gases and electrons. The first electrolyte 30 and any electrolyte disclosed herein can be generally acidic, such as an acidic polymer containing perfluorosulfonic acid (PFSA). In one aspect, the electrolyte 30 and any electrolyte disclosed herein can be a product manufactured by The Chemours Company of Wilmington, Delaware under the trademark Nafion TM In other aspects, the electrolyte 30 and any electrolyte disclosed herein may contain one or more of the following acids: phosphoric acid [H 3 PO 4 ], sulfuric acid [H 2 SO 4 ], or any other hydrogen ion (H + ) conductive acid. In one aspect, the first electrolyte 30 can comprise a proton exchange membrane (PEM), as is known in the art.

[0059] As is known in the art, the passage of gas through electrolyte 30, and through any electrolyte disclosed herein, is driven by the partial pressure gradient of the gas across the electrolyte (e.g., from one side of electrolyte 30 to the other opposing side of electrolyte 30). Thus, any undesirable non-hydrogen gas with a sufficient partial pressure gradient may also diffuse through electrolyte 30, and through any electrolyte disclosed herein. In addition to the pressure gradient across the electrolyte, defects in the electrolyte (e.g., small pores or voids in the electrolyte) may also undesirably allow gas to flow through the electrolyte (e.g., electrolyte 30).

[0060] As is known in the art, the electrode 32 may be referred to as a “cathode” 32 or a first cathode 32, which is positioned to receive at least some of the hydrogen ions (H ) transferred by the first electrolyte 30. + ). Similar to first anode 28, first cathode 32 and any cathode disclosed herein typically contains a catalyst, such as a platinum group metal-containing catalyst, suitable for using at least some of the electrons (e) according to Equation 2 known in the art. - ) reaction to enhance at least some of the hydrogen ions (H + ) reaction (i.e., reduction). 2H + +2e - =>H 2 Equation 2.

[0061] The resulting or “evolved” hydrogen (H 2 ) 34 or the second hydrogen content 34 and any non-hydrogen gas 36 or the second impurity gas content 36 are shown as Figure 1 The gas flow 38 or the second gas flow 38 in.

[0062] In one aspect, to enhance the distribution of hydrogen around the surface of the first cathode 32, Figure 1 A gas diffusion layer (GDL) and / or a flow field insert, not shown, 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 on a surface of the first cathode 32 .

[0063] According to aspects of the present invention, the second hydrogen content 34 is greater than the first hydrogen content 14 ; and the second impurity gas content 36 is less than the first impurity gas content 16 .

[0064] like Figure 1 As shown, according to various aspects of the present invention, a second gas stream 38 having a second hydrogen content 34 and a second impurity gas content 36 may then be introduced into the second MEA 26, specifically, into the electrode 40 or second anode 40 of the second MEA 26. Figure 1 In the schematic diagram of the purifier unit 10 shown, the first MEA 24 is shown as being spaced apart from the second MEA 26 to facilitate illustration and disclosure of the present invention. However, according to aspects of the present invention, the spacing between the first MEA 24 and the second MEA 26 can be minimal, for example, where the surface of the first cathode 32 can abut or contact the surface of the second anode 40. However, in one aspect, there can be at least some spacing between the surface of the first cathode 32 and the surface of the second anode 40, for example, 0.1 millimeters [mm] to 0.5 mm.

[0065] According to aspects of the present invention, and in contrast to the prior art, a second gas stream 38 having a second hydrogen content 34 and a second impurity gas content 36 can then be introduced to the second MEA 26 without removing or extracting the second gas stream 38 from the purifier unit 10. In other words, according to one aspect of the present invention, substantially all of the gas stream 38 generated at or diffused through the first cathode 32 is received by the second anode 40, although some portion of the gas stream 38 may undesirably "escape" from the purifier unit 10. For example, in one aspect, the second gas stream 38 can be allowed to move from the first cathode 32 of the MEA 24 to the second anode 40 of the MEA 26 without any intermediate operation or processing, such as without moving to the outside of the unit 10. In one aspect, the evolved hydrogen (H 2 ) formed in the first cathode 32 is removed from the purifier unit 10. 2) can be substantially immediately oxidized to hydrogen ions (H + In one aspect, the second gas stream 38 may be allowed to move directly from the first cathode 32 of the MEA 24 to the second anode 40 of the MEA 26 of the purifier unit 10 , eg, without moving outside of the unit 10 prior to reaching the second cathode 40 .

[0066] The second anode 40 is positioned to be contacted by a second gas stream 38 having a second hydrogen content 34 and a second impurity gas content 36. If the second anode 40 of the second MEA 26 is different from the first anode 28 of the MEA 24, they can be similar. The second anode 40 can be permeable to hydrogen, wherein at least some of the hydrogen content 34 and at least some of the non-hydrogen gas content 36 in the second gas stream 38 can move through the second anode 40 (e.g., along the axial direction indicated by the arrow of the second gas stream 38). In addition, the second anode 40 includes at least some catalyst, such as at least some platinum group metal-containing catalyst, which can enhance the oxidation of hydrogen to hydrogen ions (H + ) and electron (e - ), as shown in Equation 1.

[0067] In one aspect, to enhance the distribution of the second gas flow 38 around the surface of the second anode 40, Figure 1 A gas diffusion layer or GDL and / or flow field insert, not shown, may be positioned between the first cathode 32 and the second anode 40 , for example, the GDL and / or flow field insert may be applied on a surface of the second anode 40 that contacts the second gas flow 38 .

[0068] According to various aspects of the present invention, the catalyst contained in the second anode 40 promotes or enhances the oxidation of the hydrogen content 34 introduced into the second anode 40 to generate or produce hydrogen ions (H + ) and electron (e - ). In one aspect, if Figure 1 As shown by arrow 41 in FIG. 4 , the electrons (e - ) can be directed back to the first cathode 32 to supply at least some of the electrons (e - ) is used to convert hydrogen ions (H + ) is reduced to hydrogen (H 2 Due to the permeability of the second anode 40, some impurity gases and any unoxidized hydrogen (H 2 ) can move through the second anode 40 and, according to various aspects of the present invention, be introduced into or contact the electrolyte 42.

[0069] The electrolyte 42 or second electrolyte 42 of the MEA 26 is positioned and adapted to receive and transfer at least some of the hydrogen ions (H 2 ) received from the second anode 40. + ). The second electrolyte 42 comprises a gas barrier between the second anode 40 and the electrode 44. If the second electrolyte 42 is not substantially the same as the first electrolyte 30, they can be similar and comprise a gas barrier capable of transporting hydrogen ions (H + ) (e.g., selectively converting hydrogen ions (H + Any material or substance that conducts (i.e., protons) from the second anode 40 to the electrode 44. Again, as noted with respect to the electrolyte 30, in one aspect, the electrolyte 42 can be referred to as a "proton conductive material." The second electrolyte 42 can generally be acidic, for example, containing one or more of the acids identified above with respect to the first electrolyte 30. However, in one aspect, the second electrolyte 42 can comprise a PEM, as is known in the art.

[0070] As is known in the art, the electrode 44 may be referred to as a “cathode” 44 or a second cathode 44, which is positioned to receive at least some of the hydrogen ions (H ) transferred by the second electrolyte 42. + ). Similar to the second anode 40, the second cathode 44 generally contains a catalyst, such as a catalyst containing a platinum group metal, which is suitable for using at least some of the electrons (e - ) enhances at least some hydrogen ions (H + ) is reduced. The resulting or “emitted” hydrogen (H 2 ) content 20 or the third hydrogen content 20 and any non-hydrogen gas 22 or the second impurity gas content 22 are shown as Figure 1 The gas flow 18, or the exhaust gas flow 18 or the third gas flow 18.

[0071] In one aspect, to enhance the hydrogen ion (H + ) around the surface of the second cathode 44, Figure 1 A gas diffusion layer (GDL) and / or a flow field insert, not shown, may be positioned between the second electrolyte 42 and the second cathode 44 , for example, the GDL and / or the flow field insert may be applied on a surface of the second cathode 44 .

[0072] According to aspects of the invention, the third hydrogen content 20 of the third gas stream 18 is greater than the first hydrogen content 14 and the second hydrogen 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, in general, the purity of the third gas stream 18 (on a "dry basis" percentage) can be greater than the purity of the first gas stream 12. For example, the third hydrogen content 20 in the third gas stream 18 can be at least 10% higher (by volume) than the first hydrogen content 14 in the first gas stream 12. In one aspect, the third hydrogen content 20 can be 20% to 30% higher (by volume) than the first hydrogen content 14. In addition, in one aspect, the hydrogen purity of the third gas stream 18 can be at least 1000 times higher (by volume) than the first gas stream 12. In one aspect, the hydrogen purity of the third gas stream 18 can be 10,000 times to 10,000,000 [10 million] times higher (by volume) than the first gas stream 12. Typically, however, the purity of the hydrogen content of the third gas stream 18 can be 100,000 to 2,000,000 [two million] times higher (by volume) than the first gas stream 12. For example, in one aspect, the purity of the third gas stream 18 can be at least 99.99% hydrogen (by volume), or at least 99.999 (five 9s)% (by volume), or 99.9999 (six 9s)% (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 can be at most 100 ppm of impurity gas. In other aspects of the present invention, the resulting third impurity gas content 22 can be at most 20 ppm, or at most 10 ppm, or at most 5 ppm, or at most 2 ppm, or at most 1 ppm. In other aspects of the invention, the third impurity gas content 22 of the produced hydrogen 18 can be at most 750 ppb (i.e., at most 0.750 ppm), or at most 500 ppb, or at most 200 ppb, or even at most 100 ppb. As is known in the art, these impurity levels of the produced hydrogen are typically "on a dry basis".

[0073] According to aspects of the present invention, in the purifier unit 10, by moving the second gas stream 38 having the hydrogen content 34 from the first cathode 32 of the MEA 24 to the second anode 40 of the second MEA 26, not only a more compact purifier can be provided, but also a more efficient device can be provided and provide a purer hydrogen content 22 than the prior art. Among other things, moving the second gas stream 38, for example, directly from the first cathode 32 to the second anode 40 avoids the well-known increase in parts, efficiency loss, and hydrogen content loss that are characteristics of the prior art hydrogen purifier performance.

[0074] In addition, according to various aspects of the present invention, the resulting gas stream, i.e., the third gas stream 18 having a higher hydrogen content 20, can generally be provided at a higher pressure than the pressure of the feed or first gas stream 12. For example, according to various aspects of the present invention, where the pressure of the first gas stream 12 can be about 1 pound per square inch gauge [psig], the pressure of the third gas stream 18 can be at least 150 psig. In one aspect, the pressure of the third gas stream 18 can be at least 120 psig, or at least 200 psig, or even at least 10,000 [ten thousand] psig. In other aspects of the present invention, the pressure of the third gas stream 18 can be no greater than the pressure of the feed or 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.

[0075] Figure 2 is a schematic diagram of a hydrogen purifier unit 50 according to another aspect of the invention. According to this aspect, the purifier unit 50 can have many of the features of the purifier unit 10; however, the purifier unit 50 also includes at least one gas vent or release between the MEAs. According to this aspect, experiments have shown that venting or allowing at least some of the second gas flow (between the MEAs) is more efficient than purifiers that do not allow removal of at least some of the second gas flow between the MEAs. Figure 2 38) escapes from the purifier unit 50 to produce a higher hydrogen content. It is believed that this discharge of at least some of the second gas stream reduces the partial pressure of the non-hydrogen gas between the MEAs, thereby reducing the partial pressure gradient driving force of the undesirable non-hydrogen gas through the second MEA. On the other hand, since some of the desired hydrogen is lost when some of the second gas stream is removed, at least some of the hydrogen can be introduced between the MEAs to serve as "supplemental" hydrogen for the hydrogen that may be lost when some of the second gas stream is removed.

[0076] like Figure 2 As shown, in a manner similar to purifier unit 10, purifier unit 50 is positioned and adapted to receive and Figure 1 The purifier unit 10 may be configured to provide a feed or first gas stream 12 similar or identical to the first gas stream 12 shown and at least some non-hydrogen gas 16, and produce a gas stream 52 having an increased hydrogen content and a reduced non-hydrogen gas content. The gas stream 52 may be referred to as an exhaust gas stream 52 or a third gas stream 52. Similar to the purifier unit 10, the third gas stream 52 may generally include an increased hydrogen content 54 and a reduced non-hydrogen gas content 56. Figure 2 As schematically shown in FIG. 1 , similar to purifier unit 10, hydrogen purifier unit 50 generally comprises a multilayer structure having components (e.g., anodes and cathodes having thin planar or thin-layer configurations), wherein Figure 2The structure shown in may include a side elevation view or a transverse axial cross-section of a purifier unit 50, which is not drawn to scale but is drawn to facilitate the disclosure of the present invention.

[0077] In one aspect, Figure 2 The illustrated hydrogen purifier unit 50 may have a first MEA 24 substantially identical to that in the purifier unit 10 (ie, 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 to provide a first gas stream 12 having a first electrolyte 30 and a first cathode 32. Figure 1 The purifier unit 10 shown produces a second gas stream 38 having a hydrogen content 34 and a non-hydrogen gas content 36 in a substantially similar manner. As is common in the art, at least some of the input or first gas stream 12 may not diffuse through the anode 28, but rather be removed as a gas stream 13 (e.g., an "exhaust gas stream"). In addition, the hydrogen purifier unit 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 content 54 and a non-hydrogen gas content 56. However, according to Figure 2 In this aspect of the invention shown in FIG, the hydrogen purifier unit 50 includes at least one vent gas stream or replacement gas stream 58 having a non-hydrogen gas content 60 and a hydrogen content 62. It should be appreciated that the non-hydrogen gas content 60 and the hydrogen content 62 of the vent gas stream 58 may be substantially the same as the non-hydrogen gas content 36 and the hydrogen content 34 of the second gas stream 38.

[0078] In one aspect, to enhance the distribution of gas flow around the electrode surface, Figure 2 One or more gas diffusion layers (GDLs) and / or flow field inserts, not shown, may be positioned within the unit 50. For example, the unit 50 may include a GDL and / or flow field insert associated with the first anode 28, the first cathode 32, the second anode 40, and / or the second cathode 44.

[0079] According to this aspect, after the first gas stream 12 is processed by the first MEA 24 to produce the second gas stream 38 having the hydrogen content 34 and the non-hydrogen gas content 36, at least some of the gas stream 38 is removed via the gas stream 58. Removing the gas stream 58 from the gas stream 38 produces a modified or intermediate gas stream 64 having the hydrogen content 66 and the non-hydrogen gas content 68. It should be appreciated that the non-hydrogen gas content 68 and the hydrogen content 66 of the modified gas stream 64 can be substantially the same as the non-hydrogen gas content 36 and the hydrogen content 34 of the second gas stream 38. According to various aspects of the present invention, the removal of the gas stream 58 reduces the partial pressure of the non-hydrogen gas content 68 in the modified gas stream 64, and the reduction in the partial pressure reduces the partial pressure gradient of the non-hydrogen gas content 58 across the second MEA 26, thereby reducing the transfer of the non-hydrogen gas content 68 to the third gas stream 52 through the second MEA 26. Therefore, according to various aspects of the present invention, the non-hydrogen gas content 56 of the third gas stream 52 is reduced.

[0080] The removal of the gas stream 58 having the non-hydrogen gas content 60 can be implemented in various ways. In one aspect, the gas stream 58 can be removed by simply exhausting at least some of the second gas stream 38, for example, exhausting through the inherent spacing between the first MEA 24 and the second MEA 26, such as exhausting through the inherent space or gap between the surfaces of the first cathode 32 and the second anode 40. On the other hand, the gas stream 58 can be removed by providing a path, channel or groove (e.g., radial or transverse channel or groove) in the mating surface of the first cathode 32, in the mating surface of the second anode 40, or in the mating surface of the first cathode 32 and the mating surface of the second anode 40. On the other hand, the gas stream 58 can be removed by a GDL and / or flow field insert positioned between the mating surface of the first cathode 32 and the mating surface of the second anode 40. As known in the art, a GDL is typically a porous material, such as carbon paper, through which the gas stream 58 can move. On the other hand, the gas stream 58 can be removed by providing one or more spacings between the mating surface of the first cathode 32 and the mating 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 some of the second gas flow 38 through the gas flow 58 .

[0081] According to another aspect of the invention, after first gas stream 12 is processed by first MEA 24 to produce second gas stream 38 having hydrogen content 34 and non-hydrogen gas content 36, at least some hydrogen may be introduced into gas stream 38. Figure 2 As shown, in one aspect, hydrogen can be passed through (at Figure 2A gas stream 59 (shown as a dashed line in FIG. 1 ) is introduced into the second gas stream 38 to replace hydrogen 62 lost from the second gas stream 38 via the gas stream 58 and to produce a modified gas stream 64. Although, in one aspect, the gas stream 38 can be high purity hydrogen, e.g., having a purity at least greater than the hydrogen content 14 of the first gas stream 12; in other aspects, the gas stream 59 can be a hydrogen-containing gas stream having at least some hydrogen content, but can have a non-hydrogen gas content.

[0082] The introduction of the hydrogen-containing gas stream 59 (e.g., a "supplemental gas stream") can be implemented with or without removing the gas stream 58. The introduction of the gas stream 59 into the gas stream 38 can be implemented in any one or more convenient ways, such as by introducing the hydrogen-containing gas stream 59 (e.g., driven by a hydrogen partial pressure gradient) through the permeable electrolyte 42, or through the permeable first cathode 32, through the permeable GDL and / or flow field insert, or through a channel in the first cathode 32, a channel in the second anode 40, or through a channel in both the first cathode 32 and the second anode 40. Any channels that may be provided for the hydrogen-containing gas stream 59 may be located in one or both of the opposing surfaces of the first cathode 32 and the second anode 40 (i.e., the surfaces of the space occupied by the second gas stream 38). In one aspect, the supplemental hydrogen stream 59 may include at least some of the third gas stream 52 having a third hydrogen content 54. For example, as Figure 2 As shown in dashed gas stream 59A in FIG. 4 , at least some of the third gas stream 52 can be introduced into the second gas stream 38 by diffusion through the second electrolyte 42. This diffusion through the second electrolyte 42 can be referred to as "backward diffusion" of at least some of the third gas stream 52 having the third hydrogen content 54 through the second electrolyte 42 to provide at least some supplemental gas stream 59 to the second gas stream 38 or the modified gas stream 64. The supplemental gas stream 59 can be provided by any one or more of these mechanisms.

[0083] According to various aspects of the invention, the third hydrogen content 54 of the third gas stream 52 is greater than the first hydrogen content 14 and the second hydrogen 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, in general, the purity of the third gas stream 52 (on a "dry basis" basis) can be greater than the purity of the first gas stream 12. For example, in one aspect, the purity of the third hydrogen content 54 can be at least 99.99% by volume, or at least 99.999 (five 9s)% by volume, or 99.9999 (six 9s)% by volume. According to another aspect of the invention, the purity of the third gas stream 52 can be expressed based on the third impurity gas content 56. For example, in one aspect, the third impurity gas content 56 can be at most 100 ppm of impurity gas. In other aspects of the invention, the resulting third impurity gas content 56 can be at most 20 ppm, or at most 10 ppm, or at most 5 ppm, or at most 2 ppm, or at most 1 ppm. In other aspects of the invention, the third impurity gas content 56 of the produced hydrogen can be at most 750 ppb (i.e., at most 0.750 ppm), or at most 500 ppb, or at most 200 ppb, or even at most 100 ppb. As is known in the art, these impurity contents of the produced hydrogen are typically "on a dry basis".

[0084] Figure 3 8 is a schematic elevational view of a hydrogen purifier stack assembly 80 having a hydrogen purifier unit 82 (e.g., hydrogen purifier unit 10 or unit 50 disclosed herein) positioned between opposing electrically conductive but gas impermeable layers or plates 84 and 86 and between 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 known in the art, because the plates 84 and 86 may generally contain passages or channels suitable for introducing or removing gases from the unit 82. The electrically conductive layers or bus bars 88 and 90 may also be referred to as "current collectors." As shown, in one aspect, the unit 82 may include at least two MEAs, namely a first MEA 92 and at least a second MEA 94. However, it is contemplated that according to aspects of the invention, the unit 82 may include three or more MEAs 92, 94 or five or more MEAs 92, 94 (e.g., positioned between the busbars 88 and 90). In one aspect, at least 10 MEAs 92, 94 may be positioned between the busbars 88 and 90.

[0085] In one aspect, the hydrogen purifier unit 82 may be referred to as a "dual membrane electrode assembly" or "DMEA". The first MEA 92 includes a first anode 96, a first electrolyte 98, and a first cathode 90. If the first anode 96 is different from the first anode 28 disclosed herein, they may be similar; if the first electrolyte 98 is different from the first electrolyte 30 disclosed herein, they may be similar; if the first cathode 90 is different from the first cathode 32 disclosed herein, they may be similar. The second MEA 94 includes a second anode 102, a second electrolyte 104, and a second cathode 106. If the second anode 102 is different from the second anode 40 disclosed herein, they may be similar; if the second electrolyte 104 is different from the second electrolyte 42 disclosed herein, they may be similar; if the second cathode 106 is different from the second cathode 44 disclosed herein, they may be similar.

[0086] Due to the electrochemistry of the cell 82, the conductive, airtight layers or plates (or bipolar plates) 84 and 86 can generally be made of a corrosion-resistant or non-oxidizing material. Although it is contemplated that any conductive, substantially airtight and substantially corrosion-resistant material (e.g., metal) can be used for the plates 84 and 86 in various aspects of the present invention, typically, the plates 84 and 86 can be made of a conductive, substantially airtight and substantially corrosion-resistant graphite-containing material. For example, the plates 84 and 86 can be made of a material containing graphite powder and a resin. In one aspect, the bipolar plates 84 and 86 can be made of a non-metallic material (e.g., plastic) in which conductive inserts and / or particles have been placed to provide the desired conductivity.

[0087] In one aspect, it is contemplated that the bipolar plates 84 and 86 may include at least semi-permeable portions, for example, to allow for fluid permeability required for thermal and / or water management.

[0088] According to one aspect of the invention, the conductive current collectors 88 and 90 can have a relatively high conductivity (e.g., relative to the plates 84 and 86). In one aspect, the current collectors 88 and 90 can be plated (e.g., gold or silver) to enhance conductivity. For example, the current collectors 88 and 90 can comprise stainless steel plates, aluminum plates, or copper plates that can be plated with gold or silver.

[0089] According to various aspects of the present invention, Figure 3 As shown, the hydrogen (H 2 ) and a first gas stream 108 of a non-hydrogen gas may be introduced into the first anode 96, where at least some of the hydrogen (H 2 ) is oxidized to hydrogen ions (H +) and electrons (e-). The first gas stream 108 may be introduced to the first anode 96 by any conventional means, for example, via passages and / or channels in the bipolar plate 84. For example, Figure 3 As shown, the first gas stream 108 may be introduced to the first anode 96 via a plurality of transverse channels 110 communicating with a plurality of longitudinal passages or channels 112 that discharge onto the first anode 96. The first anode 96 may include a GDL and / or a flow field insert ( Figure 3 ), such as a carbon paper type GDL, to enhance the distribution of the first gas flow 108 on the surface of the first anode 96.

[0090] Once introduced into the anode 96, a bond is formed within the MEAs 92 and 94. Figure 1 and Figure 2 Reactions and fluid flows described; specifically, according to various aspects of the present invention, a second gas flow 114 ( Figure 3 ) and a third gas stream 116 from the second cathode 106. As disclosed herein, the second anode 102 receives the second gas stream 114 (also, Figure 3 In one aspect, the second anode 102 may include or be equipped with a GDL and / or a flow field insert ( Figure 3 (not shown), such as a carbon paper type GDL, to enhance the distribution of the second gas stream 114 on the surface of the second anode 102. The third gas stream 116 can be collected from the second cathode 106 by conventional means. For example, Figure 3 As shown, with or without passing through a gas diffusion layer (not shown), the third gas stream 116 can be removed from the second cathode 106 via a plurality of transverse passages 118 that communicate with a plurality of longitudinal passages or channels 120 that are in fluid communication with the second cathode 106. The plurality of transverse passages 118 can 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 in the bipolar plate 86 can be in fluid communication with one or more manifolds (e.g., vertical or longitudinal manifolds), and the one or more manifolds can be in fluid communication with one or more ports for introducing, exhausting, or redirecting gas flows.

[0091] According to various aspects of the present invention, the third gas stream 116 may contain a higher content of hydrogen (H 2) content and a lower non-hydrogen gas content. For example, as disclosed herein, the non-hydrogen gas content of the third gas stream 116 can have a non-hydrogen gas content of at most 100 ppm, or at most 20 ppm, or at most 10 ppm, or at most 5 ppm, or at most 2 ppm, or at most 1 ppm, or even at most 500 ppb on a "dry basis". In addition, the pressure of the third gas stream 116 can generally be higher than the pressure of the first gas stream 108, but in other aspects, the pressure of the third gas stream 116 can be lower than the pressure of the first gas stream 108.

[0092] Figure 3A A schematic detailed view 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. Figure 3A Is Figure 3 The details shown in 3A are marked Figure 3 A detailed view of a portion of the hydrogen purifier stack assembly 80 is shown in FIG. Figure 3A As shown, it has a hydrogen content of 34 (see Figure 1 and Figure 2 ) and a second gas stream 114 having a non-hydrogen gas content 36 exits the first cathode 100 and enters a space 101 between the mating surface of the first cathode 100 and the second anode 102. Spaces, voids, or interstitial spaces 101 typically exist between the first cathode 100 and the second anode 102 due to defects in the mating surfaces of the first cathode 100 and the second anode 102 and due to manufacturing defects and / or tolerances, etc. It is believed that these spaces or voids 101 can be tiny, but typically exist between the mating surfaces of the first cathode 100 and the second anode 102 and between the mating surfaces of other mating electrodes disclosed herein, and can provide a path for the gas stream (e.g., for removal and / or introduction of the gas stream). According to various aspects of the present invention, the second gas stream 114 typically contacts and enters the second anode 102 via direct contact or via the space 101, and according to various aspects of the present invention described herein, catalytic oxidation of the hydrogen content 34 in the second gas stream 114 occurs at the second anode 102. In one aspect, as Figure 3B As shown, the GDL 105 can be positioned between the first cathode 100 and the second anode 102 to facilitate or enhance the distribution of the second gas flow 114 over the surface of the second anode 102. In another aspect, a gas distribution or flow field insert can be positioned between the first cathode 100 and the second anode 102 (or between any electrodes disclosed herein), with or without a GDL, such as Figure 3B105 in the figure to promote or enhance the distribution of the second gas flow 114 on the surface of the second anode 102. The flow field insert can be a conductive porous or perforated plate (e.g., a porous or perforated metal plate) or a screen insert (e.g., a metal screen insert) that is positioned and suitable to provide at least some gas distribution around the surface of the second anode 102. The flow field inserts disclosed herein can also include channels or passages for allowing the introduction of gas flow from an adjacent electrode or the removal of gas flow to an adjacent electrode.

[0093] As disclosed herein, the gas purifier unit 82 may include a combination of Figure 1 The hydrogen purifier unit 10 disclosed and described, or in combination Figure 2 A hydrogen purifier unit 50 is disclosed and described. Figure 3A and Figure 3B The detailed views shown also illustrate these aspects of the invention. Figure 3 The gas purifier unit 82 in the embodiment includes a purifier unit 10, such as Figure 3A As shown, substantially all of the second gas flow 114 exiting the first cathode 100 moves (e.g., directly) by direct contact or via the space 101 to the second anode 102 (with or without the GDL 105 and / or flow field insert) for subsequent catalytic oxidation as disclosed herein.

[0094] In various aspects of the present invention, wherein Figure 3 The gas purifier unit 82 in the embodiment includes a purifier unit 50, such as Figure 3A and Figure 3B As shown, at least some of the second gas stream 114 exiting the first cathode 100 is provided as gas stream 58 (see Figure 2 ) is removed. According to this aspect, the removed gas stream 58 can contain at least some non-hydrogen gas, wherein the remaining modified gas stream has a lower non-hydrogen gas partial pressure when removed. The lower non-hydrogen gas partial pressure is less likely to be transmitted through the second electrolyte 104 and less likely to be transmitted to the output or third gas stream 116 (see Figure 3 ).like Figure 3A As shown, the removed or exhausted gas stream 58 can be moved from the space 101, and / or as shown. Figure 3B As shown, the removed or exhausted gas flow 58 may move through the GDL 105 and / or the flow field insert.

[0095] Likewise Figure 3A and Figure 3B As shown, in one aspect, the hydrogen-containing gas stream 59 (at Figure 3A and Figure 3B59A) and / or 59A may also 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 increase the hydrogen content of the second gas stream 114 introduced into the second anode 102, for example, to increase the hydrogen content of the third gas stream 116 (see Figure 3 ) (i.e., output stream 116), and / or replace at least some of the hydrogen content removed in gas stream 58. Figure 3A and Figure 3B As shown, the introduction of hydrogen-containing gas stream 59 and / or 59A into space 101 can be implemented with or without GDL 105, for example, as Figure 3B As shown, a hydrogen-containing gas flow 59 may be introduced through the gas permeable GDL 105 and / or flow field insert.

[0096] Figure 4 is a schematic perspective view of a hydrogen purifier stack 130 according to one aspect of the present invention, the hydrogen purifier stack 130 having a plurality of hydrogen purifier units 132A to 132N, for example having Figure 1 The two or more hydrogen purifier units 10 and / or Figure 2 . According to aspects of the invention, "N" is the number of purifier units that may be included in a hydrogen purifier stack 130 according to aspects of the invention. Specifically, it is contemplated that N may be in the range of 1 to 1,000 units, but may typically be in the range of 40 to 100 units, such as 80 units.

[0097] According to this aspect of the invention, each of the hydrogen purifier units 132A to 132N includes dual MEAs (DMEAs) as disclosed herein separated by electrically conductive and gas impermeable layers or plates 134A to 134N+1 (e.g., "bipolar plates"). The layers or plates 134A to 134N+1 may be similar to the combined Figure 3 The layers or plates 84 and 86 are shown and described and have the same characteristics. For example, the layers or plates 134A to 134N+1 can have one or more transverse passages and multiple axial passages or channels (e.g., flow distribution passages) that are adapted and positioned to introduce gas flows into the hydrogen purifier units 132A to 132N and / or remove gas flows from the hydrogen purifier units 132A to 132N. According to various aspects of the present invention, some of the plates 134A to 134N+1 (e.g., Figure 4The plate 134B shown in the figure may include passages, such as isolated individual passages, which are suitable and positioned to remove gas flow from the second cathode of DMEA 132A and introduce gas flow from the first anode of DMEA 132B. In contrast, the terminal plate 134A may include passages suitable and positioned to introduce gas flow only to the first anode of DMEA 132A, and the terminal plate 134N+1 may include passages suitable and positioned to remove gas flow only from the second cathode of DMEA 132N. In one aspect, the terminal plate 134A and / or the terminal plate 134N+1 may not have passages, that is, they may be completely devoid of passages.

[0098] According to various aspects of the present invention, as disclosed herein, the reduction reaction associated with the cathode according to Equation 2 can provide electrons (e - ) is used for an oxidation reaction associated with an anode (e.g., a prior / previous anode in the stack) according to Equation 1. In one aspect, such electrons (e) in the hydrogen purifier stack 130 - ) flow such that the DMEA of the hydrogen purifier stack 130 is electrically connected in series. However, for ease of illustration and disclosure of this aspect of the present invention, the electrons (e - ) flows from the second anode to the first cathode and electrons (e - The flow of electrons from the first anode to the second anode is Figure 4 Omitted in .

[0099] The hydrogen purifier stack 130 also includes opposing busbars or current collectors 136 and 138 and end plates 137 and 139 (at Figure 4 The current collectors 136 and 138 may be similar in design, size, and construction to the combined Figure 3 The illustrated and disclosed collectors 88 and 90. As is known in the art, the end plates 137 and 139 may be relatively thick metal plates that are used to help compress the stack 130, for example, via a plurality of mechanical fasteners (not shown) 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 tightened on the bolts.

[0100] like Figure 4 As shown, with hydrogen (H 2Multiple input or first gas streams 140A to 140N of hydrogen gas content and non-hydrogen gas content can be introduced to DMEA 132A to 132N via inlets and flow distribution passages in plates 134A to 134N. Figure 4 As shown, the first gas streams 140A to 140N may be, for example, via (at Figure 4 One or more gas supply manifolds 141 (eg, a common gas supply manifold) are provided. Figure 4 As shown, a plurality of exhaust or third gas streams 142A to 142N may be removed from the DMEA 132A to 132N (eg, via flow extraction passages and outlets in the plates 134A to 134N). Figure 4 As shown, the third gas streams 142A to 142N may be, for example, via (at Figure 4 The plurality of output or third gas streams 142A to 142N have a higher hydrogen (H 2 O) than the plurality of input gas streams 140A to 140N, respectively, as disclosed herein. 2 ) content and lower non-hydrogen gas content. For example, as disclosed herein, the non-hydrogen gas content of the third gas stream 142A to 142N can have a non-hydrogen gas content of at most 100 ppm, or at most 20 ppm, or at most 10 ppm, or at most 5 ppm, or at most 2 ppm, or at most 1 ppm, or even at most 500 ppb, or even at most 500 ppb on a "dry basis". According to various aspects of the present invention, each of the flows of the gas streams from the input streams 140A to 140N to the output streams 142A to 142N can flow in parallel through the DMEA 132A to 132N, for example, from one or more gas supply manifolds 141 to one or more gas collection manifolds 143.

[0101] Although the present invention is described in detail for the purpose of illustration and disclosure, Figure 4 Not shown, but in accordance with aspects of the invention, the hydrogen purifier stack 130 may generally include a plurality of anode exhaust ports, passages, and / or manifolds such that excess source gas from streams 140A through 140N is permitted to be exhausted from the hydrogen purifier stack 130 .

[0102] Likewise Figure 4As shown, the hydrogen purifier stack 130 can be powered by a voltage ΔV between current collectors 136 and 138 and a current I. The voltage ΔV can be provided: externally, for example, from one or more DC power sources, a local power grid, a fuel cell, through photovoltaic and / or wind turbines; and / or internally, for example, from the electrochemical potential and reactions occurring in the DMEA 132A to 132N in the stack 130. In one aspect, the voltage ΔV can be adjusted to adjust the current through the stack 130. Higher currents can enhance the chemical reactions within the stack 130 and increase the rate of hydrogen production. The amount of amperage required to enhance the output of various aspects of the present invention will depend on the size of the purifier and the number of units in the purifier, among other things.

[0103] Likewise Figure 4 As shown, according to one aspect of the present invention, one or more DMEAs 132A to 132N in the hydrogen purifier stack 130 may include a combination of Figure 2 The purifier unit 50 shown and described. That is, in one aspect, one or more DMEA 132A to 132N (e.g., all of DMEA 132A to 132N) can be adapted to remove at least some of the gas stream emitted from the first cathode of DMEA 132A to 132N, such as Figure 2 The second gas stream 38 shown in FIG. 1 is a second gas stream 38 shown in FIG. 1. This second gas stream 38 is a second gas stream 38 shown in FIG. 1. The ... Figure 4 144A to 144N (shown in dashed lines). Figure 4 The gas flows 144A to 144N correspond to Figure 2 As disclosed herein, according to one aspect of the present invention, it is understood that removing the gas streams 144A to 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 to 132N, thereby reducing the movement of the non-hydrogen gas through the second anode. According to one aspect, the gas streams 144A to 144N can be removed via an exhaust passage (e.g., an exhaust gas manifold ( Figure 4 (not shown)) is discharged from the hydrogen purifier stack 130.

[0104] In addition, due to Figure 4 Some of the gas streams 144A to 144N (dashed lines) in the DMEA 132A to 132N may already contain some hydrogen content, and thus, in one aspect, at least some of the hydrogen may be introduced into the second gas stream (i.e., Figure 2In some embodiments, the second gas stream 38 shown in FIG. 1 is introduced into the second anode of the DMEA 132A to 132N to make up for at least some of the lost hydrogen and increase the content of hydrogen introduced into the second anode of the DMEA 132A to 132N. By making up for any hydrogen lost via the gas streams 144A to 144N, aspects of the present invention can increase the hydrogen content of the hydrogen produced by the hydrogen purifier stack 130. This introduction of at least some hydrogen into the second gas stream of the DMEA 132A to 132N is Figure 4 In one aspect, the gas streams 146A to 146N may be routed through passages (e.g., gas manifolds ( Figure 4 )) is introduced into the hydrogen purifier stack 130.

[0105] Figure 5 1 is a schematic diagram of a hydrogen purifier unit 150 according to other aspects of the present invention. According to this aspect, the purifier unit 150 can have many of the features of the purifier unit 10 and the purifier unit 50 disclosed herein. Specifically, the purifier unit 150 includes a DMEA 152, which is positioned to receive an input or first gas stream 154 having a first hydrogen content 156 and a first non-hydrogen gas content 158, and to produce an output or third gas stream 160 having an output or third hydrogen content 162 and an output or third non-hydrogen gas content 164, the output or third hydrogen content 162 being greater than the first hydrogen content 156 and the output or third non-hydrogen gas content 164 being lower than the first non-hydrogen gas content 158. As is common in the art, at least some of the input or first gas stream 154 may not be oxidized at the anode 166, but rather removed as a gas stream 155 (e.g., an "exhaust gas stream"). Typically, the exhaust gas stream 155 may be captured and directed (e.g., via channels, manifolds, and ports) for further processing or disposal as desired.

[0106] Likewise, the pressure of the output or third gas stream 160 will typically be higher than the pressure of the input or first gas stream 154, although the 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 unit 150 includes only three electrodes, with the second electrode performing the dual function of a first cathode and a second anode, as disclosed herein.

[0107] Specifically, Figure 5As shown, the DMEA 152 of the purifier unit 150 includes 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 units 10 and 50 disclosed herein, the first anode 166 can have all the features of the first anode disclosed herein; the first electrolyte 168 and the second electrolyte 172 can have all the features of the electrolytes disclosed herein; and the second cathode 174 can have all the features of the second cathode disclosed herein.

[0108] In addition, the dual electrode 170 of the cell 150 can have all the features and characteristics of the anode or cathode disclosed herein, such as being conductive, gas permeable, and containing a catalyst. However, according to this aspect of the invention, the dual electrode 170 performs the following dual functions: First, according to Equation 2, using electrons (e - ) reduces the hydrogen ions (H) transferred through the first electrolyte 168 + ) to produce hydrogen (H 2 ), then, according to Equation 1, the oxidized hydrogen (H 2 ) to produce hydrogen ions (H + ) and electron (e - In one aspect, hydrogen (H 2 ) is oxidized in the dual electrode 170 and generates electrons (e - ) can be a hydrogen ion (H + ) The electrons consumed by the reduction in the dual electrode 170 (e - ) source. This internal transfer of electrons (e - )exist Figure 5 In the embodiment of the present invention, the electronic circuit 176 is shown in dashed lines. According to various aspects of the present invention, one or more units 150 can be used to Figure 4 Cells 132A to 132N of stack 130 are shown in FIG.

[0109] According to one aspect of the present invention, the exhaust gas flow ( Figure 2 The gas flow 58 in the cell 150 is removed from the dual electrodes 170 and / or the supplemental gas flow ( Figure 2 The gas stream 59 and / or 59A) is introduced into the dual electrodes 170 of the cell 150. Figure 5 As shown, the gas flow 178 can be removed from the dual electrode 170 (e.g., through the gas permeable structure of the dual electrode 170) to reduce the partial pressure of the non-hydrogen gas moving through the first electrode 168, as disclosed herein. In addition, with or without removing the gas flow 178, (in Figure 5 The additional hydrogen (H 2) gas stream 180 may be introduced into the dual electrode 170 (e.g., through a gas permeable structure of the dual electrode 170) to replace or increase the hydrogen (H) of the gas stream introduced into the second electrolyte 172. 2 ) content, as disclosed herein. As in other aspects of the invention, the supplementary hydrogen (H 2 ) gas flow 180 may be introduced into dual electrode 170 by at least some of gas flow 160 “back-diffusing” back through second electrode 172 to dual electrode 170 .

[0110] In one aspect, to enhance the flow of gas and / or hydrogen ions (H + ) around the electrode surface, such as the combination Figure 3B As described, Figure 5 One or more gas diffusion layers (GDLs) and / or flow field inserts, not shown, may be positioned within unit 150. For example, unit 150 may include a GDL and / or flow field insert associated with first anode 166, dual electrode 170, and / or second cathode 174.

[0111] As in other aspects of the invention, despite having only three electrodes 166, 170, and 174, the third hydrogen content 162 of the third gas stream 160 of the hydrogen purifier unit 150 is greater than the first hydrogen content 156; and the third impurity gas content 164 is less than the first impurity gas content 158. For example, the purity of the third gas stream 160 on a "dry basis" basis can be greater than the purity of the first hydrogen content 156 of the first gas stream 154. For example, in one aspect, the purity of the third gas stream 160 can be at least 99.99% hydrogen by volume, or at least 99.999 (five nines)% by volume, or 99.9999 (six nines)% by volume. According to another aspect of the invention, the purity of the third gas stream 160 can be expressed based on the third impurity gas content 164. For example, in one aspect, the third impurity gas content 164 can be at most 100 ppm of impurity gas. In other aspects of the invention, the third impurity gas content 164 produced can be at most 20 ppm, or at most 10 ppm, or at most 5 ppm, or at most 2 ppm, or at most 1 ppm. In other aspects of the invention, the third impurity gas content 164 of the produced hydrogen can be at most 750 ppb (i.e., at most 0.750 ppm), or at most 500 ppb, or at most 200 ppb, or even at most 100 ppb. As is known in the art, these impurity contents of the produced hydrogen are typically "on a dry basis".

[0112] Additionally, according to aspects of the present invention, the resulting gas stream (i.e., Figure 5The third gas stream 160 in the feedstock 154 may typically be provided at a pressure that is higher than the pressure of the feed or first gas stream 154. For example, according to various aspects of the invention, wherein the pressure of the first gas stream 154 may be at most 1 psig, the pressure of the third gas stream 160 may be at least 150 psig. In one aspect, the pressure of the third gas stream 160 may be at least 120 psig, or at least 200 psig, or even at least 10,000 [ten thousand] psig. In other aspects of the invention, the pressure of the third gas stream 160 may be no higher than the pressure of the feed or 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.

[0113] Figure 6 is a schematic diagram of a hydrogen purification system 200 according to one aspect of the present invention, wherein the hydrogen purification system 200 has one or more hydrogen purifiers 202, wherein the hydrogen purifier 202 has Figure 4 One or more hydrogen purifier stacks 130 shown in FIG. The one or more hydrogen purifier stacks 130 may include any one or more of the hydrogen purifier units disclosed herein, for example, one or more units 10, one or more units 50, and / or one or more units 150, or a combination thereof. The one or more hydrogen purifier stacks 130 may be accommodated by end plates 204 and 206, for example, similar to Figure 4 End plates 137 and 139 are shown in FIG.

[0114] like Figure 6 As shown, the hydrogen purification system 200 includes a hydrogen-containing gas source 208 operatively connected to one or more hydrogen purifiers 202 via one or more conduits or pipes 210. The hydrogen-containing gas source 208 can be a storage tank, another gas purifier 202, one or more fuel cells, or one of a variety of different industrial processes. As disclosed herein, the hydrogen-containing gas source 208 typically contains at least some non-hydrogen gas or impurity gas, such as nitrogen (N 2 ), argon (Ar), carbon dioxide (CO 2 ), carbon monoxide (CO), methane (CH 4 ) and / or oxygen (O 2 ).like Figure 6As shown, the flow of gas from the hydrogen-containing gas source 208 can be regulated by one or more flow control valves 212 (e.g., manual valves or automatic valves controlled by an appropriate control system (not shown)) and / or pressure regulators 213. In one aspect, the hydrogen-containing gas 208 can be introduced into the system 200 under pressure (e.g., by a gas pressurization device (not shown), such as one or more blowers, fans, or compressors). In another aspect, the hydrogen-containing gas 208 can be drawn into the system 200 by a gas depressurization device or vacuum device (not shown) (such as one or more blowers, fans, or compressors). For example, the vacuum source can be operatively connected to Figure 6 one or more conduits or pipes 214 in; to one or more discharge conduits 220; and / or one or more discharge conduits 221.

[0115] As disclosed herein, after the hydrogen-containing gas is introduced from source 208 and subjected to appropriate oxidation and reduction, the higher purity hydrogen is discharged from one or more hydrogen purifier stacks 202 into one or more conduits or pipelines 214 for storage or further processing 216. For example, the further processing 216 can be a dryer (dryer / desiccator) to remove at least some water vapor, and / or further purification, for example, to remove at least some trace impurities (if present). The purification process can include a pressure swing adsorption (PSA) system, a temperature swing adsorption (TSA), a "getter" gas purifier, or another gas purification system 200. In one aspect, the further processing 216 can include a liquefier, such as a cryo-cooler. As Figure 6 As shown, the flow of gas from one or more hydrogen purifier stacks 202 may be regulated by one or more flow control valves 218, such as manual valves or automated valves controlled by a suitable control system (not shown).

[0116] Likewise Figure 6 As shown, in general, the hydrogen-containing gas from source 208 may have a pressure or a first pressure P 1 , and after moving through the one or more hydrogen purifier stacks 202, the pressure of the gas introduced into the storage 216 or the third or output pressure P 2 Usually higher than the first pressure P 1 , as disclosed herein. Pressure P 2 Can be any of the output pressures disclosed herein. In one aspect, the pressure P 2 It can contain a pressure P lower than the pressure P 1 , for example, when a hydrogen-containing gas 208 is drawn into the system 200 (eg, via a vacuum).

[0117] Likewise Figure 6 As shown, in one aspect, one or more hydrogen purifier stacks 202 may include (in combination with Figure 2 ) one or more purifier units 50 having an exhaust gas stream or a replacement gas stream 58 and possibly a hydrogen-containing gas stream 59. Figure 6 As shown, the gas purification system 200 may include a system for removing a gas stream 58 ( Figure 2 ) and removes the anode exhaust gas (e.g., Figure 1 One or more exhaust conduits 221 of the anode gas stream 13 are shown, and the exhaust gas stream in conduit 220 and / or the exhaust gas stream in conduit 221 are directed to other processing, storage or disposal 222. Other processing of the gas streams in conduits 220 and 221 may include: purification, such as by another system 200, etc.; exhaust to the atmosphere; combustion by a "flare"; or other processing. Figure 6 As shown, the flow of exhaust gas from one or more hydrogen purifier stacks 202 via conduit 220 can be regulated by one or more flow control valves 224, such as manual valves or automatic valves controlled by an appropriate control system (not shown). In one aspect, at least some of the exhaust gas flow ( Figure 2 Stream 58) may be introduced into purifier 200, e.g. Figure 6 purifier 200 shown in FIG. 1 or another purifier 200 to recover and / or purify any hydrogen in the exhaust gas (e.g., in conduit 220). Figure 6 As shown, at least some of the exhaust gas ( Figure 2 58 in the flow) can be passed through (in Figure 6 The flow in conduit 223 may include appropriate flow control and / or pressure control (not shown) as disclosed herein.

[0118] In one aspect, one or more purifier units 50 may provide a hydrogen-containing "make-up" gas stream 59 (e.g., see FIG. 1 ) from a source 226 (e.g., from exhaust conduit 214 of the present system or another system 200 or other source of hydrogen) via one or more conduits or pipes 228. Figure 2). The flow of "supplemental" gas to one or more hydrogen purifier stacks 202 through one or more conduits 228 can be regulated by one or more flow control valves 230, such as manual valves or automatic valves controlled by an appropriate control system (not shown). In one aspect, the flow of "supplemental" gas to each unit of one or more hydrogen purifier stacks 202 can be regulated to control or "tune" the purity of the hydrogen produced or delivered, such as for storage or further processing 216. For example, the flow of "supplemental" gas can be regulated to control the purity of the hydrogen produced by: controlling one or more flow control valves 230; adjusting the pressure within one or more stacks 202 (e.g., the pressure detected by pressure sensor 236); introducing a flow control orifice (e.g., to conduit 228); and / or regulating the "back diffusion" of hydrogen through membranes in the units of stack 202, etc. In one aspect, the supplemental gas ( Figure 2 The flow of the flow 59) may not be as Figure 6 Rather, the source may be from within the stack 130 and delivered within the stack 130, for example, from one or more units 50 (see Figure 2 ) to one or more units 50, the flow of which can be regulated and controlled based on flow and / or pressure.

[0119] According to one aspect of the present invention, the temperature of one or more hydrogen purifier stacks 130 of the gas purification system 200 can be adjusted and controlled to optimize the DMEA purification performance of the stack 130 and / or to avoid overheating of the stack 130. For example, in one aspect, the temperature of the stack 130 can be maintained at at least 30°C, but typically maintained in the range of 50°C to 80°C. It should be understood that lowering the operating temperature of the electrolyte in each unit of the stack 130 to, for example, between 45°C and 55°C can improve the purity of the hydrogen produced while requiring more reasonable electrical power consumption. In one aspect, as Figure 6 As shown, the temperature of the one or more hydrogen purifier stacks 130 may be monitored and regulated by one or more temperature sensors 232. The temperature of the one or more hydrogen purifier stacks 130 detected by the temperature sensors 232 may be controlled by one or more heating or cooling loops regulated and controlled by an appropriate control system (not shown). The heating or cooling loops of the one or more hydrogen purifier stacks 130 may include passages in the one or more hydrogen purifier stacks 130 through which a heating or cooling fluid may pass to regulate the temperature of the one or more hydrogen purifier stacks 130.

[0120] According to one aspect of the invention, the pressure of one or more hydrogen purifier stacks 130, the pressure of the gas from source 208, and / or the pressure of the exhaust gas of the gas purification system 200 can be regulated and controlled to optimize the performance of the reaction within the DMEA of the stack 130, etc. For example, in one aspect, the pressure of the hydrogen gas produced by one or more stacks 130 can be monitored and regulated by one or more pressure sensors 234. It should be understood that in some aspects, the pressure of the hydrogen gas generated in the system 200 can affect the purity of the hydrogen gas produced. The pressure of the produced hydrogen gas detected by the pressure sensor 234 can be regulated and controlled by an appropriate control system (not shown).

[0121] Additionally, in one aspect, the pressure of one or more stacks 130 may be adjusted and controlled to enhance the performance, such as efficiency, of the DMEA of the stack 130. In one aspect, the pressure of the first cathode and / or the second anode of one or more hydrogen purifier stacks 130 may be adjusted and controlled to enhance the performance, such as efficiency, of the DMEA of the stack 130. Figure 6 As shown, the pressure of one or more stacks 130, such as the pressure of the first cathode and / or the 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 an appropriate control system (not shown).

[0122] Figure 7 2 is a schematic illustration of a water electrolyzer unit 250 according to another aspect of the present invention. According to this aspect, the water electrolyzer unit 250 unit comprises an electrochemical unit for electrolyzing water to produce hydrogen, specifically, with less undesirable impurity gases (e.g., oxygen (O 2 )) of hydrogen. Figure 7 As shown, water electrolyzer unit 250 is positioned and adapted to receive a feed or first fluid stream 252 containing water. 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 aspects of the present invention, unit 250 is adapted to produce a hydrogen gas stream or third gas stream 254 having little or no gas impurities (including little or no oxygen). Third gas stream 254 may be referred to as exhaust gas stream 254.

[0123] like Figure 7 As schematically shown in FIG. 2 , in a manner similar to the hydrogen purifier unit disclosed herein, the water electrolyzer unit 250 generally comprises a multilayer structure having components (e.g., an anode and a cathode having a thin planar or thin layer configuration), wherein Figure 7The structure shown in the figure may include a side elevation view or a transverse axial cross-section view of a water electrolyzer unit 250, which is not drawn to scale but is drawn to facilitate the disclosure of the present invention.

[0124] According to aspects of the present invention, to provide the required hydrogen 254, the water electrolyzer unit 250 generally includes a first MEA 256 and at least one second MEA 258. The first MEA 256 includes a first anode 260, which can be generally fluid-permeable, specifically water-permeable or gas-permeable, in a manner similar to other anodes disclosed herein, wherein at least some of the water in the first fluid stream 252 can move (e.g., along the axial direction indicated by the arrow of the first fluid stream 252) into the anode 260. In addition, the anode 260 includes at least some catalyst, such as at least some platinum group metal-containing or iridium-containing catalyst, which can enhance the oxidation of water into gaseous oxygen (O 2 ), hydrogen ion (H + ) and electron (e - ), for example, according to Eq. 3. H 2 O=>1 / 2O 2 +2e - +2H + Equation 3.

[0125] In one aspect, to enhance the distribution of the first fluid stream 252 around the surface of the anode 260, Figure 7 An electrically conductive gas diffusion layer (GDL) and / or flow field insert not shown in the drawings can be positioned between the first fluid stream 252 and the anode 260, for example, the GDL can be applied on the surface of the anode 260 that is contacted by the first fluid stream 252. In one aspect, the GDL for the cell 250 or the GDL layer used in any aspect disclosed herein can be a metal-based GDL, such as a platinum-coated titanium GDL or its equivalent.

[0126] Due to the permeability of the anode 260, water (H 2 O) moves into the anode 260, and due to the conductivity of the anode 260, the electrons (e - ) are conducted away from the anode 260, and according to various aspects of the present invention, the hydrogen ions (H + ) is introduced into electrolyte 262. Electrolyte 262 can be similar to any other electrolyte disclosed herein, for example, electrolyte 262 can be an acidic electrolyte.

[0127] As is common in the art, at least some of the input or first fluid stream 252 may not diffuse through the anode 260, but rather be removed as a fluid stream 264, e.g., an “exhaust gas stream.” Typically, the exhaust gas stream 264 may be captured and directed (e.g., via channels, manifolds, and ports) for further processing or disposal as desired.

[0128] The electrolyte 262 or first electrolyte 262 is positioned and adapted to receive and transfer at least some of the hydrogen ions (H + Since the anode 260 is in close proximity to the electrolyte 262, hydrogen ions (H + ) moves from the anode 260 to the electrolyte 262. The first electrolyte 262 comprises a barrier between the first anode 260 and the electrode 266. The first electrolyte 262 may comprise a barrier capable of transporting hydrogen ions (H + ) (e.g., selectively converting 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 can be referred to as a "proton conducting material" while substantially preventing the flow of gases. The first electrolyte 262 can be generally acidic, for example, an acidic polymer containing perfluorosulfonic acid (PFSA). In one aspect, the electrolyte 262 can be a Nafion® manufactured by The Chemours Company of Wilmington, Delaware under the trademark Nafion TM In other aspects, the electrolyte 262 may contain one or more of the following acids: phosphoric acid [H 3 PO 4 ], sulfuric acid [H 2 SO 4 ], or any other hydrogen ion (H + ) conductive acid. In one aspect, the first electrolyte 262 can include a proton exchange membrane (PEM), as is known in the art.

[0129] As is known in the art, the electrode 266 may be referred to as a “cathode” 266 or a first cathode 266, which is positioned to receive at least some of the hydrogen ions (H 264) transferred by the first electrolyte 262. + ). Similar to other cathodes disclosed herein, first cathode 266 is fluid permeable and typically contains a catalyst, such as a platinum group metal-containing catalyst, which is suitable for using at least some of the electrons (e - ) reaction to enhance at least some of the hydrogen ions (H + ) reaction (ie, reduction), as is known in the art. 2H + +2e - =>H2 Equation 4.

[0130] The resulting or "released" hydrogen (H 2 )268 or contains hydrogen (H 2 ) is transferred through the gas permeable first cathode 266, such as Figure 7 As shown in the figure as gas flow 268 or second fluid flow 268.

[0131] In one aspect, to enhance the hydrogen (H 2 ) around the surface of the second anode 270, Figure 7 A gas diffusion layer (GDL) and / or a flow field insert, not shown, may be positioned between the first cathode 266 and the second anode 270 , for example, the GDL and / or the flow field insert may be applied on a surface of the second anode 270 .

[0132] like Figure 7 As shown, according to various aspects of the present invention, the hydrogen (H 2 ) is introduced into the second MEA 258, specifically, into the electrode 270 or the second anode 270 of the second MEA 258. Figure 7 In the schematic diagram of the electrolyzer unit 250 shown, the first MEA 256 is shown as being spaced apart from the second MEA 258 to facilitate illustration and disclosure of the present invention. However, according to aspects of the present invention, the spacing between the first MEA 256 and the second MEA 270 can be minimal, for example, where the surface of the first cathode 266 can abut or contact the surface of the second anode 270. However, in one aspect, there can be at least some spacing between the surface of the first cathode 266 and the surface of the second anode 270, for example, 0.1 millimeters [mm] to 0.5 mm.

[0133] According to aspects of the present invention, and in contrast to the prior art, the hydrogen (H 2 ) can be introduced into the second MEA 258 without removing or extracting the second fluid stream 268 from the electrolyzer unit 250. In other words, according to one aspect of the present invention, although some portion of the second fluid stream 268 may undesirably "escape" from the electrolyzer unit 250, substantially 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 move from the first cathode 266 of the MEA 256 to the second anode 270 of the MEA 258 without any intermediate operation or processing, such as without passing outside the electrolyzer unit 250. In one aspect, the hydrogen (H 2 O) formed in the first cathode 266 is discharged. 2) can be substantially immediately oxidized to hydrogen ions (H+) at the second anode 270. In one aspect, the second fluid stream 268 can be allowed to move directly from the first cathode 266 of the MEA 258 to the second anode 270 of the MEA 258 of the electrolyzer unit 250, e.g., without having to move outside of the electrolysis unit 250 before reaching the second cathode 270.

[0134] The second anode 270 is positioned to be filled with hydrogen (H 2 ). If the second anode 270 of the second MEA 258 is different from the first anode 260 of the MEA 256, they can be similar. The second anode 270 can be permeable to hydrogen, wherein at least some of the hydrogen in the second fluid stream 268 can move through the second anode 40 (e.g., along the axial direction indicated by the arrow of the second fluid stream 268). In addition, the second anode 270 includes at least some catalyst, such as at least some platinum-containing catalyst, which can enhance the oxidation of hydrogen into hydrogen ions (H + ), as indicated by Equation 1 reproduced below. H 2 =>2H + +2e - Equation 1.

[0135] In one aspect, to enhance the distribution of the second fluid stream 268 around the surface of the second anode 270, Figure 7 A gas diffusion layer or GDL and / or flow field insert, not shown, may be positioned between second fluid stream 268 and second anode 270 , for example, the GDL and / or flow field insert may be applied to a surface of second anode 270 contacted by second fluid stream 268 .

[0136] According to various aspects of the present invention, the catalyst contained in the second anode 270 promotes or enhances the oxidation of hydrogen in the second fluid stream 268 to generate or produce hydrogen ions (H) according to the above equation 1. + ) and electron (e - ). In one aspect, if Figure 7 As shown by arrow 272 in FIG. 1 , the electrons (e - ) can be directed back to the first cathode 266 to provide for the conversion of hydrogen ions (H + ) is reduced to hydrogen (H 2 ) of at least some of the electrons (e - Due to the permeability of the second anode 270, at least some of the hydrogen (H 2 ) can move through the second anode 270 and, according to various aspects of the present invention, be introduced into or contact the electrolyte 274.

[0137] The electrolyte 274 or second electrolyte 274 of the MEA 258 is positioned and adapted to receive and transfer at least some of the hydrogen ions (H 2+) received from the second anode 270. + ). The second electrolyte 274 comprises a gas barrier between the second anode 270 and the cathode 276. If the second electrolyte 274 is not substantially the same as the first electrolyte 262, they can be similar and comprise a gas barrier capable of transporting hydrogen ions (H + ) (e.g., selectively converting hydrogen ions (H + Any material or substance that can transport protons (i.e., protons) from the second anode 270 to the cathode 276). Again, as noted in conjunction with the first electrolyte 262, in one aspect, the second electrolyte 274 can be referred to as a "proton conductive material." The second electrolyte 274 can generally be acidic, for example, containing one or more of the acids identified herein. However, in one aspect, the second electrolyte 274 can include a PEM, as is known in the art.

[0138] The electrode 276 or second cathode 276 is positioned to receive at least some of the hydrogen ions (H + ). Similar to the second anode 266, the second cathode 276 is generally permeable and contains a catalyst, such as a platinum group metal-containing catalyst, which is suitable for using at least some of the electrons (e) according to Equation 2 reproduced below. - ) enhances at least some hydrogen ions (H + )'s restoration. 2H + +2e - =>H 2 Equation 2. The resulting or "released" hydrogen (H 2 ) or contain hydrogen (H 2 ) is produced by the electrolyzer unit 250.

[0139] In one aspect, to enhance the hydrogen ion (H + ) around the surface of the second cathode 276, Figure 7 A gas diffusion layer (GDL) or flow field insert not shown in the figure can be positioned between the second electrolyte 274 and the second cathode 276, for example, the GDL and / or the flow field insert can be applied on the surface of the second cathode 276. In one aspect, Figure 7 A GDL or flow field insert, not shown, may be positioned adjacent the downstream surface of the second cathode 276 to enhance removal of the third fluid stream 254 .

[0140] According to aspects of the present invention, the third fluid stream 254 of the electrolysis unit 250 may generally contain hydrogen gas (H2) with little or no undesirable impurity gases (e.g., little or no oxygen). 2 ).

[0141] According to aspects of the present invention, in the electrolysis unit 250, a more efficient means for providing purer hydrogen can be provided than in the prior art by moving the second fluid stream 268 from the first anode 266 of the MEA 256 to the second cathode 270 of the second MEA 258. In addition, moving the second fluid stream 268 from the first cathode 266 (e.g., directly) to the second anode 270 minimizes the content of impurities (e.g., oxygen impurities) in the third fluid stream 254.

[0142] Figure 8 is a schematic illustration of a water electrolyzer unit 300 according to another aspect of the invention. According to this aspect, electrolyzer unit 300 can have many of the features of electrolyzer unit 250; however, electrolyzer unit 300 also includes at least one gas exhaust or release between the MEAs. It is believed that this reduction in the content of the second fluid flow reduces the partial pressure of the non-hydrogen gas (e.g., the partial pressure of oxygen) between the MEAs and, therefore, reduces the partial pressure gradient driving force of the undesirable non-hydrogen gas through the second MEA. On the other hand, since some of the desired hydrogen is lost when some of the second fluid flow is removed, at least some of the hydrogen can be introduced between the MEAs to serve as "supplemental" hydrogen to the hydrogen that may be lost when some of the second fluid flow is removed.

[0143] like Figure 8 As shown, the water electrolyzer unit 300 is positioned and adapted to receive a feed or first fluid stream 302 to the electrolyzer unit 300. According to aspects of the present invention, the unit 300 is adapted to produce a hydrogen gas stream or third fluid stream 304 with little or no gas impurities (including little or no oxygen). The third gas stream 254 may be referred to as an exhaust gas stream 254. Figure 8 , similar to the electrolyzer unit 250, generally comprises a multilayer structure having components (e.g., anodes and cathodes having thin planar or thin layer configurations), wherein Figure 8 The structure shown in the figure may include a side elevation view or a cross-sectional view of the electrolyzer unit 300, which is not drawn to scale but is drawn to facilitate the disclosure of the present invention.

[0144] In one aspect, Figure 8The electrolyzer unit 300 shown in FIG. 2 may have a first MEA 306 substantially the same as in the electrolyzer unit 250, namely, a first anode 308, a first electrolyte 310, and a first cathode 312 to oxidize and reduce the first fluid stream 302 to react with the first electrolyte 310. Figure 7 The MEA 256 of the electrolyzer unit 250 shown generates hydrogen (H) in substantially the same manner. 2 ) of the second fluid stream 314. As is common in the art, at least some of the input or first fluid stream 302 may not be oxidized at the first anode 308, but rather removed as a fluid stream 303 (e.g., an "exhaust fluid stream"). In addition, the electrolyzer unit 300 may have a substantially identical second MEA 316 having a second anode 318, a second electrolyte 320, and a second cathode 322 to provide a second electrolyte stream 314 for use with the first anode 308. Figure 7 The electrolyzer unit 250 shown in FIG. 2 is substantially similar to the electrolyzer unit 250 in that it oxidizes and reduces the second fluid stream 314 to produce a gas containing hydrogen (H 2 ) of the third fluid stream 304. However, according to Figure 8 In various aspects of the invention shown, electrolyzer unit 300 includes at least one exhaust gas stream or replacement gas stream 324 having hydrogen and a non-hydrogen gas (eg, oxygen).

[0145] In one aspect, to enhance the distribution of gas flow around the electrode surface, Figure 8 One or more gas diffusion layers (GDLs) and / or gas distribution media, not shown, may be positioned within electrolyzer cell 300. For example, electrolyzer cell 300 may include a GDL and / or flow field insert associated with first anode 308, first cathode 312, second anode 318, and / or second cathode 322.

[0146] According to this aspect, after the first fluid stream 302 is processed and moved through the first MEA 306 to produce the second fluid stream 314 having a hydrogen gas content and a non-hydrogen gas content 36, at least some of the second fluid stream 314 is removed via a fluid stream 324. Removing the fluid stream 324 from the fluid stream 314 produces a modified or intermediate fluid stream 326. According to aspects of the present invention, the removal of 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, thereby reducing the movement of the non-hydrogen gas through the second MEA 316 to the third fluid stream 304. Therefore, according to aspects of the present invention, the non-hydrogen gas content (e.g., oxygen content) of the third fluid stream 304 is reduced, thereby providing a purer hydrogen gas stream.

[0147] The removal of the fluid stream 324 can be implemented by various means. In one aspect, the fluid stream 324 can be removed by simply discharging at least some of the second fluid stream 314, for example, by discharging through the inherent spacing between the first MEA 306 and the second MEA 316, for example, by discharging through the inherent space or gap between the surface of the first cathode 312 and the second anode 318. On the other hand, the fluid stream 324 can be removed by providing a path, channel or groove (e.g., radial channel or groove, or transverse channel or groove) in the mating surface of the first cathode 312, in the mating surface of the second anode 318, or in the mating surface of the first cathode 312 and the mating surface of the second anode 318. On the other hand, the fluid stream 324 can be removed by positioning the GDL and / or flow field insert between the mating surface of the first cathode 312 and the mating surface of the second anode 318. As known in the art, the GDL is generally a porous material through which the gas stream 324 can move, such as carbon paper. In another aspect, the fluid stream 324 can be removed by providing one or more spaces between the mating surface of the first cathode 312 and the mating surface of the second anode 318 to provide a path for the fluid stream 324. In one aspect, a sub-atmospheric pressure source (i.e., a vacuum) can be introduced to draw at least some of the second fluid stream 314 through the fluid stream 324.

[0148] According to another aspect of the invention, after the first fluid stream 302 is processed and moved through the first MEA 306 to produce the second fluid stream 314, at least some of the hydrogen can be introduced into the second fluid stream 314. Figure 8 As shown, in one aspect, hydrogen can be passed through (at Figure 8 302) is introduced into the second gas stream 314 to replace the hydrogen lost from the second fluid stream 314 via the fluid stream 324 and produce a modified gas stream 326. While in one aspect, the fluid stream 328 can be high purity hydrogen, e.g., having a purity at least greater than the hydrogen content of the first fluid stream 302; in other aspects, the fluid stream 328 can be a hydrogen-containing gas stream having at least some hydrogen content but can have non-hydrogen gas content.

[0149] The introduction of a hydrogen-containing gas stream 328 (e.g., a "supplemental gas stream") into the electrolysis cell 300 can be performed with or without removal of the fluid stream 324. The introduction of the fluid stream 328 into the second fluid stream 314 can be performed in any one or more convenient ways, such as by introducing the hydrogen-containing gas stream 328 through the electrolyte 310, which can be gas-permeable (e.g., driven by a hydrogen partial pressure gradient), or a gas-permeable first cathode 312, a gas-permeable GDL and / or flow field insert, or a channel in the first cathode 312, a channel in the second anode 318, or a channel in both the first cathode 312 and the second anode 318. Any channels that can provide for the hydrogen-containing gas stream 328 can be located in one or both of the opposing surfaces of the first cathode 312 and the second anode 318.

[0150] In one aspect, the supplemental hydrogen stream 328 can include at least some of the third fluid stream 304 having a hydrogen content. For example, at least some of the third fluid stream 304 can be introduced into the second fluid stream 314 by diffusion through the second electrolyte 320, such as Figure 8 This diffusion through the second electrolyte 320 can be referred to as at least some hydrogen (H 2 ) of the third fluid stream 304. The supplemental gas stream 328 may be provided by any one or more of these sources or mechanisms.

[0151] In another aspect of the present invention, Figure 5 The three-electrode unit 150 shown can also be used as an electrolysis device. Figure 5 As shown, the DMEA 152 of the purifier unit 150 includes 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. Figure 7 The components and operation of the electrolyzer unit 250 are shown in Figure 5 In the electrolyzer unit 50 shown, the anode 166 can have all the features of the first anode disclosed herein; the first electrolyte 168 and the second electrolyte 172 can have all the features of the electrolyte disclosed herein; and the second cathode 174 can have all the features of the second cathode disclosed herein. In this aspect of the invention, Figure 5 The components and fluid flows of the electrolyzer unit 150 shown may have all the functions and features of the purifier unit 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, for the electrolyzer unit 150, Figure 5The first fluid stream 154 in the can contain liquid water and / or gaseous water (i.e., steam). (It should be understood that any reference to "fluid" herein can refer to a liquid fluid, a gaseous fluid, or both a liquid fluid and a gaseous fluid.) According to various aspects of the present invention, Figure 5 The electrolyzer unit 150 may be adapted to produce a hydrogen gas stream or a third fluid stream 160 having little or no gaseous impurities, including little or no oxygen.

[0152] According to various aspects of the present invention, one or more water electrolysis units 250 and 300 may be provided to generate high purity hydrogen. In one aspect, a water electrolysis stack having one or more electrolysis units 250 and / or 300 may be provided, for example, similar to Figure 4 In addition, in one aspect, a water electrolysis device system having one or more electrolysis unit stacks having one or more electrolysis units 250 and / or 300, such as similar to Figure 6 The water electrolysis of the hydrogen purification system 200 shown in FIG.

[0153] As described above, various embodiments of the present invention in their many aspects provide improved hydrogen purification and water electrolysis that meet and can exceed the hydrogen purity required by hydrogen users. Various aspects of the present invention employ a unique combination of membrane electrode assemblies (MEAs) or dual MEAs (DMEAs) that have been shown to provide the desired improved hydrogen purity.

[0154] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present disclosure. As used herein, the singular forms "a / an" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that when used in this specification, the terms "comprises and / or comprising" specify the presence of the features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0155] The corresponding structures, materials, functions, and equivalents of all means or step plus function elements in the following claims are intended to include any structure, material, or function for performing a function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for the purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present disclosure. The embodiments are selected and described in order to best explain the principles and practical applications of the present disclosure, and to enable others of ordinary skill in the art to understand the various different embodiments of the present disclosure with various different modifications suitable for the intended specific use.

[0156] Although several aspects of the invention have been described and illustrated herein, those skilled in the art may implement alternative aspects to achieve the same objectives. It is therefore intended that the appended claims cover all such alternative aspects that fall within the true spirit and scope of the invention.

Claims

1. A hydrogen purifier unit (10, 50, 150), the hydrogen purifier unit (10, 50, 150) comprising: A first membrane electrode assembly (MEA) (24), the first MEA (24) comprising: a first anode (28) positioned to contact a first gas stream (12) having a first hydrogen gas content and a first impurity gas content, the first anode containing a catalyst adapted to oxidize at least some of the first hydrogen gas content to produce hydrogen ions and electrons; a first electrolyte (30) positioned and adapted to receive at least some of the hydrogen ions produced by the first anode (28); as well as a first cathode (32) positioned to receive at least some of the hydrogen ions transferred from the first electrolyte (30), the first cathode containing a catalyst adapted to reduce the at least some of the hydrogen ions to produce a second gas stream (38) having a second hydrogen content and a second impurity gas content, the second hydrogen content being greater than the first hydrogen content and the second impurity gas content being less than the first impurity gas content; and A second MEA (26), the second MEA (26) comprising: a second anode (40) positioned to receive the second gas stream (38) from the first cathode (32) of the first MEA, the second anode containing a catalyst adapted to oxidize at least some of the second hydrogen content in the second gas stream (38) to produce hydrogen ions and electrons; a second electrolyte (42) positioned and adapted to receive and transfer at least some of the hydrogen ions produced by the second anode (40); as well as a second cathode (44) positioned to receive at least some of the hydrogen ions transferred by the second electrolyte (42) of the second MEA, the second cathode containing a catalyst suitable for reducing the at least some of the hydrogen ions to produce a third gas stream (18, 52) having a third hydrogen content and a third impurity gas content, the third hydrogen content being greater than the first hydrogen content and the third impurity gas content being less than the first impurity gas content.

2. The hydrogen purifier unit (10, 50, 150) of claim 1, wherein the purifier unit further comprises at least one passage between the first electrolyte (30) and the second electrolyte (42) for discharging at least some of the second gas stream (38).

3. The hydrogen purifier unit (10, 50, 150) of claim 2, wherein the at least one passage is located between the first cathode (32) and the second anode (40).

4. The hydrogen purifier unit (10, 50, 150) of claim 3, wherein the at least one passage between the first cathode and the second anode comprises a gap (101) between mating surfaces of the first cathode and the second anode.

5. The hydrogen purifier unit (10, 50, 150) of claim 3, wherein the purifier unit further comprises a gas permeable layer (GDL) (105) between the first cathode and the second anode, and wherein the GDL provides the at least one passage between the first cathode and the second anode.

6. The hydrogen purifier unit (10, 50, 150) of claim 5, wherein the GDL (105) comprises a carbon-based gas permeable layer.

7. The hydrogen purifier unit (10, 50, 150) of any one of claims 2 to 6, wherein the at least one passage comprises at least one channel proximate to at least one of the first cathode and the second anode.

8. The hydrogen purifier unit (10, 50, 150) of any one of claims 1 to 7, wherein the purifier unit further comprises at least one passage between the first electrolyte and the second electrolyte for introducing a hydrogen-containing gas into the second gas flow.

9. The hydrogen purifier unit (10, 50, 150) of claim 8, wherein the at least one passage is located between the first cathode and the second anode.

10. The hydrogen purifier unit (10, 50, 150) of claim 9, wherein the at least one passage between the first cathode and the second anode comprises a void between mating surfaces of the first cathode and the second anode.

11. The hydrogen purifier unit (10, 50, 150) of claim 9, wherein the purifier unit further comprises a gas permeable layer (GDL) (105) between the first cathode and the second anode, and wherein the GDL provides the at least one passage between the first cathode and the second anode.

12. The hydrogen purifier unit (10, 50, 150) of any one of claims 8 to 11, wherein the at least one passage comprises at least one channel in a surface of at least one of the first cathode and the second anode.

13. The hydrogen purifier unit (10, 50, 150) of any one of claims 1 to 12, wherein the first gas flow comprises a first gas pressure and the third gas flow comprises a third gas pressure, wherein the third gas pressure is greater than the first gas pressure.

14. The hydrogen purifier unit (10, 50, 150) of any one of claims 1 to 13, wherein the catalyst in the first anode, the first cathode, the second anode, and the second cathode comprises a catalyst containing a platinum group metal.

15. The hydrogen purifier unit (10, 50, 150) of any one of claims 1 to 14, wherein the first electrolyte and the second electrolyte comprise at least an acidic electrolyte.

16. A method for reducing an impurity gas content of a gas stream (12), the gas stream (12) having a hydrogen content (14) and an impurity gas content (16), the method comprising: introducing a first gas stream (12) having a first hydrogen content and a first impurity gas content into a first anode (28) containing a catalyst; In the first anode (28), catalytically oxidizing at least some of the first hydrogen gas content to produce hydrogen ions and electrons; transferring at least some of the hydrogen ions and diffusing at least some of the impurity gas content through the first electrolyte (30) to a first cathode (32) containing a catalyst; catalytically reducing, in the first cathode (32), at least some of the hydrogen ions transferred through the first electrolyte (30) to produce a second gas stream (38) having a second hydrogen content (34) and a second impurity gas content (36), the second hydrogen content (34) being greater than the first hydrogen content and the second impurity gas content (36) being less than the first impurity gas content; introducing the second gas stream (38) into a second anode (40) having a catalyst; catalytically oxidizing at least some of the second hydrogen content in the second gas stream (38) in the second anode (40) to produce hydrogen ions and electrons; transferring at least some of the hydrogen ions generated at the second anode (40) through a second electrolyte (42) and diffusing at least some of the second impurity gas content (36) to a second cathode (44); as well as In the second cathode (44), at least some of the hydrogen ions transferred through the second electrolyte (42) are catalytically reduced to produce a third gas stream (18, 52) having a third hydrogen content (54) and a third impurity gas content (56), the third hydrogen content (54) being greater than the first hydrogen content and the third impurity gas content (56) being less than the first impurity gas content.

17. The method of claim 16, further comprising removing at least some of the second gas stream (38) to produce a modified gas stream (66) having a non-hydrogen gas partial pressure lower than the non-hydrogen gas partial pressure in the second gas stream.

18. The method of claim 17, wherein introducing the second gas stream to the second anode comprises introducing the modifying gas stream (66) to the second anode.

19. A method according to claim 17 or claim 18, wherein removing at least some of the second gas flow (38) comprises removing at least some of the second gas flow through a passage between the first electrolyte and the second electrolyte.

20. The method of claim 19, wherein the via is located between the first cathode and the second anode.

21. The method of claim 20, wherein the passage between the first cathode and the second anode comprises a gap (101) between mating surfaces of the first cathode and the second anode.

22. The method of claim 20 or claim 21, wherein removing the at least some of the second gas flow (38) comprises removing the at least some of the second gas flow through a gas diffusion layer (GDL) positioned between the first cathode and the second anode.

23. The method of any one of claims 20 to 22, wherein removing the at least some of the second gas flow comprises removing the at least some of the second gas flow through at least one channel in a surface of at least one of the first cathode and the second anode.

24. A method according to any one of claims 16 to 23, wherein the method further comprises introducing some hydrogen (59) into the second gas stream.

25. The method of claim 24, wherein introducing some hydrogen into the second gas stream supplements at least some hydrogen (59A) removed from the second gas stream.

26. The method of any one of claims 16 to 25, wherein the third hydrogen content is at least 99.999% hydrogen by volume on a dry basis.

27. The method according to any one of claims 16 to 26, wherein the third impurity gas content is at most 10 ppm on a dry basis.

28. A method for reducing an impurity gas content of a gas stream (12), the gas stream (12) having a hydrogen content (14) and an impurity gas content (16), the method comprising: introducing a first gas stream (12) having a first hydrogen content (14) and a first impurity gas content (14) into a first membrane electrode assembly (MEA) (24) having a first anode (28) containing a catalyst, a first electrolyte (30) and a first cathode (30) to produce a second gas stream (38) having a second hydrogen content (34) and a second impurity gas content (36); and The second gas stream (38) is moved directly to a second MEA (26) having a second anode (40) containing a catalyst, a second electrolyte (42) and a second cathode (44) to produce a third gas stream (18, 52) having a third hydrogen content (20, 54) greater than the first hydrogen content and a third impurity gas content (22, 56) less than the first impurity gas content.

29. The method of claim 28, wherein the first MEA (24) and the second MEA (26) are positioned in a hydrogen purifier unit (10, 50, 150), and moving the second gas flow directly to the second MEA (26) includes moving the second gas flow to the second MEA without allowing the second gas flow to exit the hydrogen purifier unit.

30. The method of claim 28 or claim 29, wherein the method further comprises removing at least some of the second gas stream (38) to produce a modified second gas stream (66), the modified second gas stream (66) having a lower non-hydrogen gas partial pressure than the second gas stream.

31. The method of claim 30, wherein the method further comprises introducing at least some hydrogen (59, 59A) into the second gas stream.

32. A hydrogen purification system (200), comprising: At least one hydrogen purifier unit (10, 50, 150) as claimed in claim 1; and At least two electrically conductive plates (204, 206), one of the at least two plates being mounted to a first end of at least one hydrogen purifier unit (10) and one of the at least two plates being mounted to a second end of the at least one hydrogen purifier unit opposite the first end.

33. The hydrogen purification system (200) of claim 32, wherein the at least one hydrogen purifier unit comprises a plurality of hydrogen purifier units (10, 50, 150).

34. The hydrogen purification system (200) of claim 32 or claim 33, wherein the plurality of hydrogen purifier units comprises a hydrogen purifier stack.

35. The hydrogen purification system (200) according to any one of claims 32 to 34, wherein the system further comprises a power supply adapted to provide voltage and current to the at least one hydrogen purifier unit.

36. The hydrogen purification system (200) of claim 35, wherein the power source comprises a DC power source.

37. A hydrogen purification system (200), comprising: At least one hydrogen purifier unit (10, 50, 150) as claimed in claim 2; and At least two electrically conductive plates (204, 206), one of the at least two plates being mounted to a first end of at least one hydrogen purifier unit (10, 50, 150) and at least one of the at least two plates being mounted to a second end of the hydrogen purifier unit opposite the first end.

38. The hydrogen purification system (200) of claim 37, wherein the system further comprises at least one manifold (143) operably connected to at least one passage for discharging at least some of the second gas stream.

39. The hydrogen purification system (200) of claim 38, wherein the at least one manifold (143) is operably connected to a conduit having a control valve adapted to regulate the flow of exhaust of at least some of the second gas stream.

40. The hydrogen purification system (200) of claim 39, wherein the system further comprises a conduit for directing the flow of at least some of the exhausted second gas stream to an inlet of the at least one hydrogen purifier unit.

41. A hydrogen purifier unit (10, 50, 150), the hydrogen purifier unit (10, 50, 150) comprising: A membrane electrode assembly (MEA) (152), the MEA (152) comprising: an anode (166) positioned to contact a first gas stream (154) having a first hydrogen gas content (156) and a first impurity gas content (158), the anode containing a catalyst adapted to oxidize at least some of the first hydrogen gas content to produce hydrogen ions and electrons; a first electrolyte (168) positioned and adapted to receive and transfer at least some of the hydrogen ions received from the anode; a dual electrode (170) positioned to receive at least some of the hydrogen ions transferred from the first electrolyte, the dual cathode containing a catalyst adapted to reduce the at least some of the hydrogen ions to produce a second gas stream having a second hydrogen content and to oxidize at least some of the second hydrogen content in the second gas stream to produce hydrogen ions and electrons; a second electrolyte (172) positioned and adapted to receive and transfer at least some of the hydrogen ions received from the dual electrodes; and a cathode (174) positioned to receive at least some of the hydrogen ions transferred from the second electrolyte, the cathode containing a catalyst suitable for reducing the at least some of the hydrogen ions and the electrons to produce a third gas stream (160), the third gas stream (160) having a third hydrogen content (162) and a third impurity gas content (164), the third hydrogen content (162) being greater than the first hydrogen content and the third impurity gas content (164) being less than the first impurity gas content.

42. The hydrogen purifier unit (10, 50, 150) of claim 41, wherein the unit further comprises at least one passage for removing at least some of the second gas stream.

43. The hydrogen purifier unit (10, 50, 150) of claim 42, wherein said at least one passage comprises said dual electrodes (170).

44. The hydrogen purifier unit (10, 50, 150) of claim 43, wherein said at least one passageway comprises the permeability of said dual electrodes.

45. The hydrogen purifier unit (10, 50, 150) of any one of claims 42 to 44, wherein the at least one passage comprises a gas permeable diffusion layer.

46. ​​The hydrogen purifier unit (10, 50, 150) of any one of claims 42 to 45, wherein the at least one passage comprises the second electrolyte.

47. A hydrogen purifier unit (10, 50, 150) according to any one of claims 41 to 46, wherein the unit further comprises at least one passage for introducing at least some hydrogen into the second gas stream.

48. The hydrogen purifier unit (10, 50, 150) of claim 47, wherein said at least one passage comprises said dual electrodes.

49. The hydrogen purifier unit (10, 50, 150) of any one of claims 42 to 48, wherein the at least one passage comprises a gas permeable diffusion layer.

50. The hydrogen purifier unit (10, 50, 150) of any one of claims 42 to 49, wherein the at least one passage comprises the second electrolyte.

51. A method for purifying hydrogen, the method comprising: introducing a first gas stream (154) having a first hydrogen content (156) and a first impurity gas content (158) to an anode (160) containing a catalyst; In the anode (160), catalytically oxidizing at least some of the first hydrogen gas content to produce hydrogen ions and electrons; transferring at least some of the hydrogen ions generated in the anode to the dual electrodes (170) through the first electrolyte (168); In the dual electrode (170), catalytically reducing at least some of the hydrogen ions transferred through the first electrolyte to produce a second gas stream having a second hydrogen content, and catalytically oxidizing at least some of the second hydrogen content in the second gas stream to produce hydrogen ions and electrons; transferring at least some of the hydrogen ions generated in the dual electrodes to a cathode (174) through a second electrolyte (172), and In the cathode (174), at least some of the hydrogen ions transferred through the second electrolyte are catalytically reduced to produce a third gas stream (160) having a third hydrogen content (162) and a third impurity gas content (164), the third hydrogen content (162) being greater than the first hydrogen content and the third impurity gas content (164) being less than the first impurity gas content.

52. The method of claim 51, further comprising removing at least some of the second gas flow.

53. The method of claim 52, wherein the MEA further comprises a gas diffusion layer, and wherein removing the at least some of the second gas flow comprises removing the at least some of the second gas flow through the gas diffusion layer.

54. The method of claim 51 or claim 52, wherein the dual electrode (170) comprises a gas permeable electrode, and wherein removing the at least some of the second gas flow comprises removing the at least some of the second gas flow through the gas permeable dual electrode.

55. The method of any one of claims 52 to 54, wherein removing the at least some second gas flow comprises removing the at least some second gas flow through the second electrolyte.

56. The method of any one of claims 51 to 55, wherein the method further comprises introducing at least some hydrogen (180) into the second gas stream.

57. The method of claim 56, wherein the MEA further comprises a gas diffusion layer, and wherein introducing the at least some of the hydrogen (180) into the second gas stream comprises introducing the at least some of the hydrogen into the second gas stream through the gas diffusion layer.

58. A method according to claim 56 or claim 57, wherein the dual electrode (170) comprises a gas permeable electrode, and wherein introducing the at least some hydrogen gas (180) into the second gas flow comprises introducing the at least some hydrogen gas into the second gas flow through the gas permeable dual electrode.

59. The method of any one of claims 56 to 58, wherein introducing the at least some hydrogen gas (180) into the second gas stream comprises introducing the at least some hydrogen gas into the second gas stream through the second electrolyte.

60. The method of any one of claims 51 to 59, wherein the third impurity gas content (164) comprises at most 10 ppm impurity gas on a dry basis.

61. A water electrolysis device unit (250), the water electrolysis device unit (250) comprising: A first membrane electrode assembly (MEA) (256), the first MEA (256) comprising: a first anode (260) positioned to contact a first H2O-containing fluid stream (252), the first anode containing a catalyst adapted to oxidize at least some of the H2O in the first H2O-containing fluid stream to produce oxygen, hydrogen ions, and electrons; a first electrolyte (262) positioned and adapted to receive and transfer at least some of the hydrogen ions generated by the first anode (260); as well as a first cathode (266) positioned to receive at least some of the hydrogen ions transferred from the first electrolyte (262), the first cathode containing a catalyst suitable for reducing the at least some of the hydrogen ions to produce a second fluid stream (268) containing hydrogen gas; A second MEA (258), the second MEA (258) comprising: a second anode (270) positioned to receive a second fluid stream (268) containing hydrogen gas from the first cathode of the first MEA, the second anode containing a catalyst suitable for oxidizing at least some of the hydrogen gas to produce hydrogen ions and electrons; a second electrolyte (274) positioned and adapted to receive and transfer at least some of the hydrogen ions produced by the second anode; as well as A second cathode (276) is positioned to receive at least some of the hydrogen ions transferred from the second electrolyte of the second MEA, the second cathode containing a catalyst suitable for reducing the at least some of the hydrogen ions to produce a third fluid stream containing hydrogen gas.

62. The water electrolyzer unit (250) of claim 61, wherein the electrolyzer unit further comprises at least one passage between the first electrolyte and the second electrolyte for discharging at least some of a second fluid flow.

63. The water electrolyzer unit (250) of claim 62, wherein the at least one passage is located between the first cathode and the second anode.

64. The water electrolyzer unit (250) of claim 63, wherein the at least one passage between the first cathode and the second anode comprises a gap (101) between mating surfaces of the first cathode and the second anode.

65. A water electrolyser unit (250) according to claim 63 or claim 64, wherein the water electrolyser unit further comprises a gas permeable layer (GDL) (105) between the first cathode and the second anode, and wherein the GDL provides the at least one passage between the first cathode and the second anode.

66. The water electrolyzer unit (250) of any one of claims 61 to 65, wherein the water electrolyzer unit further comprises at least one passage between the first electrolyte and the second electrolyte for introducing a hydrogen-containing gas into a second gas flow.

67. The water electrolyzer unit (250) of claim 66, wherein the at least one passage is located between the first cathode and the second anode.

68. The water electrolyzer unit (250) of claim 67, wherein the at least one passage between the first cathode and the second anode comprises a gap between mating surfaces of the first cathode and the second anode.

69. A water electrolyser unit (250) according to claim 67 or claim 68, wherein the water electrolyser unit further comprises a gas permeable layer (GDL) between the first cathode and the second anode, and wherein the GDL provides the at least one passage located between the first cathode and the second anode.

70. The water electrolyzer unit (250) of any one of claims 61 to 69, wherein the at least one passage comprises at least one channel in a surface of at least one of the first cathode and the second anode.

71. A method for electrolyzing water, the method comprising: introducing a first H2O-containing fluid stream (252) to a first anode (260) containing a catalyst; In the first anode (260), catalytically oxidizing at least some of the H2O in the first H2O-containing fluid stream to produce oxygen, hydrogen ions, and electrons; transferring at least some of the hydrogen ions through a first electrolyte (262) to a first cathode (266) containing a catalyst; catalytically reducing, in the first cathode (266), at least some of the hydrogen ions transferred through the first electrolyte to produce a second gas stream having hydrogen gas; introducing the second gas stream having hydrogen to a second anode having a catalyst (270); catalytically oxidizing at least some of the hydrogen in the second gas stream in the second anode (270) to produce hydrogen ions and electrons; transferring at least some of the hydrogen ions generated at the second anode to a second cathode (276) through a second electrolyte (277); as well as In the second cathode (276), at least some of the hydrogen ions transferred through the second electrolyte are catalytically reduced to produce a third gas stream (254) having hydrogen gas.

72. The method of claim 71, wherein the method further comprises removing at least some of the second gas stream (268) to produce a modified gas stream having a non-hydrogen gas partial pressure.

73. The method of claim 72, wherein introducing the second gas stream to the second anode comprises introducing the modifying gas stream to the second anode.

74. The method of claim 73, wherein removing at least some of the second gas flow (268) comprises removing at least some of the second gas flow through a passage between the first electrolyte and the second electrolyte.

75. The method of claim 74, wherein the via is located between the first cathode and the second anode.

76. The method of claim 75, wherein the passage between the first cathode and the second anode comprises a gap between mating surfaces of the first cathode and the second anode.

77. The method of claim 75 or claim 76, wherein removing the at least some of the second gas flow comprises removing the at least some of the second gas flow through a gas diffusion layer (GDL) positioned between the first cathode and the second anode.

78. The method of any one of claims 75 to 77, wherein removing the at least some of the second gas flow comprises removing the at least some of the second gas flow through at least one channel in a surface of at least one of the first cathode and the second anode.

79. The method according to any one of claims 71 to 78, wherein the method further comprises introducing some hydrogen into the second gas stream (268).

80. The method of any one of claims 72 to 79, wherein the method further comprises introducing some hydrogen into the second gas stream (268) to make up for at least some of the hydrogen removed from the second gas stream.

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