Multilayer composite membrane for hydrogen separation

Abstract

A device includes a porous substrate and a multilayer film. The porous substrate has a pore structure configured to allow hydrogen molecules to diffuse through the porous substrate. The multilayer film is configured to split hydrogen molecules into at least one of hydrogen atoms or protons in response to contacting the hydrogen molecules in the gas stream. The multilayer film is configured to allow passage of hydrogen atoms or protons through the multilayer film while blocking passage of larger compounds than hydrogen molecules that may be present in the gas stream. The hydrogen atoms or protons bind after passing through the multilayer film to reform hydrogen molecules. The multilayer film includes a first metal layer, an intermediate layer, and a second metal layer.

Description

Priority requirements

[0001] This application claims priority to U.S. Patent Application No. 18 / 331,483, filed June 8, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the separation of hydrogen from a gas. Background Technology

[0003] Hydrogen is the lightest element. Under standard conditions, hydrogen is a diatomic gas and is colorless, odorless, tasteless, non-toxic, and flammable. Hydrogen is the most abundant chemical substance in the universe. Most of the hydrogen on Earth exists in molecular form, such as in water and organic compounds (like hydrocarbons). Some examples of the uses of hydrogen include fossil fuel processing (e.g., hydrocracking) and ammonia production. Hydrogen is also an energy carrier.

[0004] Synthesis gas (also known as syngas) is a fuel gas mixture that includes hydrogen, carbon monoxide, and sometimes carbon dioxide. Synthesis gas is combustible and can be used as fuel for internal combustion engines. In some cases, syngas can be used as an intermediate in the production of synthetic petroleum products for use as fuel or lubricant. Syngas can also be used to produce methanol. As another example, hydrogen can be separated from syngas for use in various processes. Summary of the Invention

[0005] This disclosure describes techniques related to the separation of hydrogen from gases. The subject matter described herein can be implemented through specific embodiments to achieve one or more of the following advantages. The composite membranes described herein exhibit high permeability and high separation coefficients for hydrogen and can be scaled up in size (e.g., in length and surface area) and quantity to meet industrial-scale hydrogen separation requirements. The composite membranes described herein include an intermediate layer of graphene and / or graphene oxide sandwiched between catalytic metal layers (e.g., including palladium or palladium-based alloys), which can reduce the amount of expensive metals (such as palladium) used to manufacture such membranes. By sandwiching the graphene or graphene oxide layers between the catalytic metal layers, any impurities (e.g., non-hydrogen compounds) can be blocked from passing through the composite membrane, thereby improving the purity of hydrogen separated from the remainder of the gas stream. The composite membranes described herein may include catalytic metal layers with reduced thickness compared to conventional membranes, which in turn increases the flux of hydrogen through the composite membrane and reduces the cost of the composite membrane. In some cases, the catalytic metal layer of the composite membrane can have a greater thickness to enable the separation of high-purity hydrogen, as well as increased thermal and chemical stability. The composite membrane described herein is configured to allow hydrogen atoms and protons to pass through while blocking atoms and / or molecules larger than hydrogen atoms. Therefore, the composite membrane described herein can also be implemented in applications where proton separation is desired. For example, the composite membrane described herein can complement or replace proton membranes in various applications.

[0006] Certain aspects of the described subject matter can be implemented as an apparatus for separating hydrogen molecules from a gas stream. The apparatus includes a porous substrate and a multilayer membrane. The porous substrate has a pore structure. The pore structure is configured to allow hydrogen molecules to diffuse through the porous substrate. The multilayer membrane is disposed on the surface of the porous substrate. The multilayer membrane is configured to split (crack) a hydrogen molecule present in the gas stream into at least one of hydrogen atoms or protons. The multilayer membrane is configured to allow the hydrogen atoms or protons to pass through the multilayer membrane while blocking compounds larger than hydrogen molecules that may be present in the gas stream. The hydrogen atoms or protons recombine after passing through the multilayer membrane to reform hydrogen molecules. The multilayer membrane includes a first metal layer, a second metal layer, and an intermediate layer. The first metal layer contains palladium. The second metal layer contains palladium. The intermediate layer is disposed between the first metal layer and the second metal layer. The intermediate layer contains at least one of graphene or graphene oxide.

[0007] This aspect, along with others, may include one or more of the following features: The porous substrate may be metallic. The multilayer film may be coupled to the surface of the porous substrate via an interlayer. The interlayer may contain at least one of alumina, zirconium oxide, cerium oxide, or silicon oxide. The first metal layer may be made of a first alloy. The first alloy may contain at least one of gold, silver, yttrium, copper, platinum, or ruthenium and palladium. The second metal layer may be made of a second alloy. The second alloy may contain at least one of gold, silver, yttrium, copper, platinum, or ruthenium and palladium. The thickness of each of the first and second metal layers may be in the range of about 1 micrometer (μm) to about 2 μm. The thickness of the multilayer film may be in the range of about 3 micrometers (μm) to about 10 μm. The porous substrate and the multilayer film may be in the form of a tube. The second metal layer may be the outermost layer of the tube, and the porous substrate may be the innermost layer of the tube.

[0008] Certain aspects of the described subject matter can be implemented as a method for preparing a composite membrane for separating hydrogen molecules from a gas stream. A first metal layer is disposed on a porous substrate. The porous substrate has a pore structure. The pore structure is configured to allow hydrogen molecules to diffuse through the porous substrate. The first metal layer comprises palladium. An intermediate layer is disposed on the first metal layer. The intermediate layer comprises at least one of graphene or graphene oxide. A second metal layer is disposed on the intermediate layer. The second metal layer comprises palladium. The first metal layer, the intermediate layer, the second metal layer, and the porous substrate form a composite membrane. The composite membrane is heat-treated to homogenize its thickness and composition.

[0009] This aspect and other aspects may include one or more of the following features. The porous substrate may be metallic. An interlayer may be disposed on the porous substrate before the first metal layer is disposed. The interlayer may contain at least one of alumina, zirconium oxide, cerium oxide, or silicon oxide. Disposing the first metal layer on the porous substrate may include disposing the first metal layer on an interlayer already disposed on the porous substrate. The first metal layer may be made of a first alloy. The first alloy may contain at least one of gold, silver, yttrium, copper, platinum, or ruthenium and palladium. The second metal layer may be made of a second alloy. The second alloy may contain at least one of gold, silver, yttrium, copper, platinum, or ruthenium and palladium. The thickness of each of the first and second metal layers may be in the range of about 1 μm to about 2 μm. The thickness of the multilayer film may be in the range of about 3 μm to about 10 μm. The porous substrate and the multilayer film may be in the form of a tube. The second metal layer may be the outermost layer of the tube. The porous substrate may be the innermost layer of the tube.

[0010] Certain aspects of the described subject matter can be implemented as a method. A gas stream is brought into contact with the surface of a composite membrane. The gas stream contains hydrogen molecules. The composite membrane comprises a porous substrate and a multilayer membrane. The multilayer membrane comprises a first metal layer, an intermediate layer, and a second metal layer. The first metal layer contains palladium. The second metal layer contains palladium. The intermediate layer contains at least one of graphene or graphene oxide. The composite membrane separates at least a portion of the hydrogen molecules from the gas stream. Separating at least a portion of the hydrogen molecules from the gas stream includes, in response to contact with the gas stream, splitting at least a portion of the hydrogen molecules into at least one of hydrogen atoms or protons through the multilayer membrane. Separating at least a portion of the hydrogen molecules from the gas stream includes, through the multilayer membrane, preventing the passage of compounds larger than hydrogen molecules that may be present in the gas stream, while allowing hydrogen atoms or protons to pass through the multilayer membrane.

[0011] This aspect and other aspects may include one or more of the following features: The porous substrate may be metallic. The multilayer film may be coupled to the surface of the porous substrate via an interlayer. The interlayer may include at least one of alumina, zirconium oxide, cerium oxide, or silicon oxide. The first metal layer may be made of a first alloy. The first alloy may contain at least one of gold, silver, yttrium, copper, platinum, or ruthenium and palladium. The second metal layer may be made of a second alloy. The second alloy may contain at least one of gold, silver, yttrium, copper, platinum, or ruthenium and palladium. The thickness of each of the first and second metal layers may be in the range of about 1 μm to about 2 μm. The thickness of the multilayer film may be in the range of about 3 μm to about 10 μm. The porous substrate and the multilayer film may be in the form of a tube. The second metal layer may be the outermost layer of the tube. The porous substrate may be the innermost layer of the tube. Contacting the gas flow with the surface of the composite film may include allowing the gas flow to pass through the outer peripheral surface of the second metal layer. Hydrogen molecules separated from the gas flow may flow into and through the inner pores defined by the porous substrate.

[0012] Details of one or more embodiments of the subject matter of this disclosure are set forth in the accompanying drawings and description. Other features, aspects, and advantages will be apparent from the description, drawings, and claims. Attached Figure Description

[0013] Figure 1A This is a schematic diagram of an exemplary composite membrane for separating hydrogen from a gas stream.

[0014] Figure 1B This is a schematic diagram of an exemplary composite membrane for separating hydrogen from a gas stream.

[0015] Figure 2A This is a schematic diagram of an exemplary device for separating hydrogen from a gas stream.

[0016] Figure 2B yes Figure 2AAn enlarged schematic diagram of the cross-section of the device.

[0017] Figure 3 This is a flowchart of an exemplary method for preparing an apparatus for separating hydrogen from a gas stream.

[0018] Figure 4 This is a flowchart of an exemplary method for separating hydrogen from a gas stream.

[0019] Figure 5A This is a schematic diagram of an exemplary reactor including an exemplary composite membrane for separating hydrogen from a gas stream.

[0020] Figure 5B yes Figure 5A A schematic diagram of the cross-section of the reactor.

[0021] Figure 5C This is a plot showing the change in hydrogen and nitrogen fluxes over time through an exemplary composite membrane.

[0022] Figure 5D This is a plot showing the change in hydrogen flux over time through an exemplary composite membrane. Detailed Implementation

[0023] This disclosure describes a composite membrane for separating hydrogen from a gas stream. The composite membrane includes a porous substrate, a first metal layer, a graphene or graphene oxide layer, and a second metal layer. The porous substrate may include a metal or ceramic and is covered by an intermediate layer. The intermediate layer is configured to prevent interdiffusion between the substrate and the first metal layer. The intermediate layer also reduces the surface roughness and pore size of the porous substrate. The metal layers are hydrogen-selective because they selectively allow hydrogen to diffuse through the composite membrane while substantially blocking the diffusion of other compounds present in the gas mixture. The addition of the graphene or graphene oxide layer further prevents leakage of impurities through potential defects in the outer (second) metal layer. The addition of the graphene or graphene oxide layer can reduce the thickness of the metal layers, which can lead to higher permeability and lower manufacturing costs. The metal layers may be made of palladium or an alloy containing palladium.

[0024] Figure 1AThis is a schematic diagram of an exemplary composite membrane 100A for separating hydrogen from a gas stream. The composite membrane 100A includes a porous substrate 110 and a multilayer membrane 120. The porous substrate 110 is configured to allow hydrogen molecules to diffuse through it. The porous substrate 110 has a pore structure 112 defining a plurality of pores that allow hydrogen molecules to diffuse through it. The multilayer membrane 120 is disposed on the surface of the porous substrate 110. The multilayer membrane 120 is configured to split hydrogen molecules into hydrogen atoms, protons, or both in response to contact with hydrogen molecules present in the gas stream. The multilayer membrane 120 is configured to allow hydrogen atoms and / or protons (generated by splitting hydrogen molecules) to pass through it while blocking compounds larger than hydrogen molecules that may be present in the gas stream. For example, the gas flow may include syngas, and in such a case, the multilayer membrane 120 is configured to allow hydrogen atoms and / or protons to pass through while blocking the passage of carbon monoxide, carbon dioxide, hydrogen sulfide, water, one or more hydrocarbons, or any combination thereof. After passing through the multilayer membrane 120, the hydrogen atoms and / or protons recombine to reform hydrogen molecules, which can diffuse through the porous substrate 110. Thus, the composite membrane 100A separates hydrogen molecules from the remainder of the gas flow. The hydrogen molecules remain on one side of the porous substrate 110 of the composite membrane 100A, while the remainder of the gas flow remains on the opposite side of the multilayer membrane 120. Because the multilayer membrane 120 allows hydrogen protons to pass through while blocking atoms and / or molecules larger than hydrogen atoms, the multilayer membrane 120 can also be implemented in applications other than hydrogen separation. For example, the multilayer membrane 120 can be implemented in any application in which proton separation is desired. As an example, the multilayer membrane 120 can be implemented to complement or replace proton membranes (such as proton ceramic membranes or proton exchange membranes).

[0025] In some embodiments, the porous substrate 110 is made of a ceramic material. The ceramic material constituting the porous substrate 110 may include, for example, α-alumina (α-Al₂O₃), titanium dioxide (TiO₂), zirconium dioxide (ZrO₂), or any combination thereof. The porous substrate 110 may be made, for example, of a ceramic material having an asymmetric structure having a range of pore sizes (e.g., from about 70 nanometers (nm) to about 1000 nm) or a symmetric structure having a range of pore sizes (e.g., from about 100 nm to about 300 nm). In some embodiments, the porous substrate 110 has a tubular (e.g., cylindrical) shape with no curvature along its longitudinal length. In some embodiments, the pore structure 112 of the porous substrate 110 defines pores of uniform size. For example, the pore structure 112 of the porous substrate 110 may have a uniform pore size distribution without defects. In some embodiments, the pore structure 112 of the porous substrate 110 defines pores of different sizes. These pores can be regularly shaped (e.g., spherical) or irregularly shaped. In some embodiments, the pore structure 112 defines channels across multiple pores. In some embodiments, the pore structure 112 of the porous substrate 110 defines pores with an average pore diameter in the range of about 70 nm to about 300 nm (e.g., about 200 nm). In some embodiments, the thickness of the porous substrate 110 ranges from about 0.6 mm to about 1 mm.

[0026] The multilayer film 120 includes a first metal layer 122a and a second metal layer 122b. Both the first metal layer 122a and the second metal layer 122b contain palladium. For example, the first metal layer 122a may be made of pure palladium or an alloy containing palladium. For example, the second metal layer 122b may be made of pure palladium or an alloy containing palladium. In some embodiments, the first metal layer 122a and the second metal layer 122b have the same composition. In some embodiments, the first metal layer 122a and the second metal layer 122b have different compositions. The multilayer film 120 includes an intermediate layer 124 disposed between the first metal layer 122a and the second metal layer 122b. The intermediate layer 124 contains graphene, graphene oxide, or both. The metal layers (122a, 122b) of the multilayer film 120 catalytically split hydrogen molecules into hydrogen atoms and / or protons. The intermediate layer 124 of the multilayer membrane allows hydrogen atoms and / or protons (generated by splitting hydrogen molecules) to pass through the multilayer membrane 120, while blocking compounds larger than hydrogen molecules that may be present in the gas flow. Including the intermediate layer 124 in the multilayer membrane 120 is advantageous for blocking non-hydrogen compounds, while also allowing the individual metal layers (122a, 122b) of the multilayer membrane 120 to have a smaller thickness compared to conventional membranes (used for separating hydrogen from other gases) containing similar (and expensive) metal components. Furthermore, the intermediate layer 124 can improve the heat resistance, chemical resistance, mechanical strength, or any combination thereof of the composite membrane. In some implementations, the thickness of the intermediate layer 124 is in the range of about 0.3 nm to about 4 nm.

[0027] In some embodiments, the first metal layer 122a is made of an alloy comprising at least one of gold, silver, yttrium, copper, platinum, or ruthenium and palladium. In some embodiments, the second metal layer 122b is made of an alloy comprising at least one of gold, silver, yttrium, copper, platinum, or ruthenium and palladium. In some embodiments, the first metal layer 122a is made of the same or similar alloy as the second metal layer 122b. In some embodiments, the first metal layer 122a is made of an alloy comprising the same components as the alloy constituting the second metal layer 122b, but with different concentrations of one or more components. In some embodiments, the thickness of the first metal layer 122a is in the range of about 1 μm to 10 μm (e.g., about 3 μm). In some embodiments, the thickness of the second metal layer 122b is in the range of about 1 μm to 10 μm (e.g., about 3 μm). In some embodiments, the first metal layer 122a and the second metal layer 122b have the same thickness. In some embodiments, the first metal layer 122a and the second metal layer 122b have different thicknesses. In some embodiments, the thickness of the multilayer film 120 is in the range of about 3 μm to 10 μm (e.g., about 3 μm to about 4 μm). Increasing the thickness of the first metal layer 122a, the second metal layer 122b, the intermediate layer 124, or any combination thereof can improve the mechanical stability of the composite film 100B, which in turn can extend the service life of the composite film 100B.

[0028] Figure 1B This is a schematic diagram of an exemplary composite membrane 100B for separating hydrogen from a gas stream. The composite membrane 100B can be used with... Figure 1A The composite membrane 100A shown is substantially similar. For example, composite membrane 100B may include the same or similar components as composite membrane 100A. Composite membrane 100B includes a porous substrate 110 and a multilayer membrane 120.

[0029] In some embodiments, the porous substrate 110 is made of a metallic material. The porous substrate 110 may be made of, for example, stainless steel (such as 304 or 316 grade stainless steel), a nickel-chromium-iron-molybdenum alloy (such as Hastelloy X), or a nickel-chromium-based superalloy (such as Inconel). The metallic material constituting the porous substrate 110 may, for example, have a media grade designation of 0.1 to 1. The porous substrate 110 may have a tubular shape. In some embodiments, at least one end of the tubular porous substrate is a closed end made of a dense metal that is impermeable to protons and / or gases.

[0030] The composite membrane 100B may include a sandwich layer 115. The sandwich layer 115 may be disposed between the porous substrate 110 and the multilayer membrane 120. The sandwich layer 115 may include at least one of alumina (Al2O3), zirconium oxide (ZrO2), cerium oxide (CeO2), or silicon dioxide (SiO2). One or more of the aforementioned oxides may be incorporated into the sandwich layer 115, for example, by dip-coating. The sandwich layer 115 may, for example, improve the adhesion between the porous substrate 110 and the multilayer membrane 120, improve the structural stability of the composite membrane 100B, mitigate and / or eliminate the extraction of one or more metals (such as palladium) from the multilayer membrane 120 into the porous substrate 110, or any combination thereof. In some embodiments, the thickness of the sandwich layer 115 is in the range of about 0.5 μm to 2 μm. Although in Figure 1A The composite membrane 100A may optionally include a sandwich 115, for example, between the porous substrate 110 and the multilayer membrane 120 of the composite membrane 100A.

[0031] Figure 2A This is a schematic diagram of an exemplary apparatus 200 for separating hydrogen from a gas stream 202. Apparatus 200 can be used with... Figure 1A The composite membrane 100A shown is or Figure 1B The composite membrane 100B shown is substantially similar. For example, the device 200 may include components that are the same as or similar to those of the composite membrane 100A or 100B. The device 200 includes a porous substrate 110 and a multilayer membrane 120. The device 200 may be, for example, an embodiment of the composite membrane 100A or 100B in a tubular form. In some embodiments, the multilayer membrane 120 is located on the outside of the device 200, while the porous substrate 110 is inside the multilayer membrane 120. For example, the multilayer membrane 120 may be the outer cylindrical portion of the device 200, and the porous substrate 110 may be the inner cylindrical portion of the device 200. In some embodiments, the second metal layer 122b is the outermost layer of the tubular device 200, and the porous substrate 110 is the innermost layer of the tubular device 200. In some embodiments, the layers constituting the tubular device 200 are arranged in the following order from the outside to the inside: second metal layer 122b, intermediate layer 124, first metal layer 122a, and porous substrate 110. In some embodiments, the porous substrate 110 fills the internal pores of the multilayer film 120. In some embodiments, the porous substrate 110 itself defines the internal pores. Although in Figure 2ANot shown, but in some embodiments, device 200 includes a sandwich layer 115. In embodiments where device 200 includes a sandwich layer 115, the sandwich layer 115 may be an intermediate cylindrical portion of device 200 disposed between porous substrate 110 and multilayer film 120. In such embodiments, the layers constituting tubular device 200 may be arranged in the following order from the outside to the inside: second metal layer 122b, intermediate layer 124, first metal layer 122a, sandwich layer 115, and porous substrate 110. In some embodiments, the outer diameter of device 200 is in the range of about 0.3 cm to about 2.5 cm.

[0032] Gas flow 202 contains hydrogen molecules. Gas flow 202 can be any gas flow containing hydrogen molecules. Gas flow 202 can, for example, include syngas, which contains hydrogen molecules. In some embodiments, gas flow 202 includes pressure swing adsorption tail gas, refinery tail gas, petrochemical tail gas, steel industry tail gas, ammonia cracking outlet flow (which contains hydrogen and ammonia), or any combination thereof. Device 200 can, for example, be disposed within conduit 250 in which gas flow 202 flows. In such a case, gas flow 202 can flow within an annular space 252 defined between conduit 250 and device 200. Gas flow 202 can flow across the outer surface of device 200. For example, gas flow 202 can flow laterally across the outer surface of multilayer membrane 120. Hydrogen molecules 202a diffused through porous substrate 110 can, for example, be flowed separately to a separate process for further processing or output to a pipeline or end user. The remaining portion 202b of the gas flow 202 can continue to flow out of the annular space 252, for example, to a separate process for further processing (e.g., further separation of one or more other components). One end of the device 200 can be connected to another conduit (not shown). For example, Figure 2A The right end of the device 200 shown can be connected to a pipe (not shown) to flow hydrogen molecules 202a to a separate process for further processing or to output to a pipeline or end user. Figure 2A The left end of the device 200 shown may be, for example, a separate, closed end. In some embodiments, the device 200 may be mounted within the reactor bed along with a granulated or structured catalyst configured to accelerate the rate of a chemical reaction (e.g., steam reforming, water-gas shift reaction, dehydrogenation, or ammonia cracking). In such embodiments, the gas stream 202 may contain additional reactive species such as propane, butane, mixtures of hydrocarbons with a carbon number ranging from 1 (e.g., methane) to 10 (e.g., decane), ammonia, or any combination thereof.

[0033] Figure 2B yes Figure 2AAn enlarged schematic diagram of a cross-section of the device 200. When the gas flow 202 flows over the outer surface of the multilayer membrane 120, in response to contact with the gas flow 202, the multilayer membrane 120 catalytically splits hydrogen molecules present in the gas flow 202 into hydrogen atoms and / or protons. Because the multilayer membrane 120 selectively allows hydrogen atoms and / or protons to pass through while blocking other compounds, hydrogen atoms and / or protons diffuse into the pores defined by the multilayer membrane 120. After passing through the multilayer membrane 120, hydrogen atoms and / or protons 202a recombine to reform hydrogen molecules, which then diffuse through the porous substrate 110. Thus, non-hydrogen compounds remain on the outside of the device 200, while hydrogen molecules flow through the interior of the device 200.

[0034] Figure 3 This is a flowchart of an exemplary method 300 for producing a composite membrane for separating hydrogen from a gas stream. Method 300 can be implemented, for example, to produce any of composite membrane 100A, composite membrane 100B, or apparatus 200. At block 302, a first metal layer (e.g., first metal layer 122a) is disposed on a porous substrate (e.g., porous substrate 110). At block 304, an intermediate layer (e.g., intermediate layer 124) is disposed on the first metal layer 122a. At block 306, a second metal layer (e.g., second metal layer 122b) is disposed on the intermediate layer 124. The first metal layer 122a, intermediate layer 124, second metal layer 122b, and porous substrate 110 form a composite membrane. At block 308, the composite membrane is heat-treated to equalize its thickness and composition.

[0035] Heat treatment of the composite membrane at box 308 improves its thermal stability. Heat treatment at even higher temperatures can further improve the thermal stability of the composite membrane. As an example, heat treatment at box 308 can minimize, stabilize, and / or eliminate leakage of unwanted gases (such as nitrogen) through the composite membrane. As another example, heat treatment at box 308 can stabilize (e.g., homogenize) the flux of hydrogen (e.g., hydrogen atoms and / or protons) through the composite membrane. In addition to improving microstructure and reducing impurities in the composite membrane, heat treatment at box 308 (especially at higher temperatures) can significantly reduce, stabilize, and / or eliminate leakage of unwanted gases (such as nitrogen) through the composite membrane. For example, heat treatment at box 308 may include exposing the composite membrane to temperatures ranging from about 650 degrees Celsius (°C) to about 700°C for a period ranging from about 2 hours to about 7 days. Heat treatment at box 308 may include annealing the composite membrane. In some embodiments, the annealing time for the heat treatment performed at frame 308 can be reduced by annealing the composite membrane at increased pressure (e.g., about 12 bar to about 30 bar).

[0036] In some embodiments, the porous substrate 110 is metallic, and method 300 includes forming an interlayer (such as interlayer 115) on the porous substrate 110 prior to forming the first metal layer 122a. As previously described, interlayer 115 may comprise alumina, zirconium oxide, or both. In such embodiments, forming the first metal layer 122a on the porous substrate 110 at block 302 includes forming the first metal layer 122a on the interlayer 115 already formed on the porous substrate 110. For example, the first metal layer 122a may be formed on the interlayer 115 at block 302 via a dip-coating technique.

[0037] In some embodiments, disposing a first metal layer 122a on the porous substrate 110 at frame 302 includes disposing and / or growing a layer of material (e.g., pure palladium or a palladium-based alloy) constituting the first metal layer 122a on the porous substrate 110. For example, the first metal layer 122a can be disposed on the porous substrate 110 at frame 302 by physical vapor deposition (such as sputtering or electron beam evaporation), chemical vapor deposition, electroless plating, electroplating, or any combination thereof.

[0038] In some embodiments, disposing the intermediate layer 124 on the first metal layer 122a at block 304 includes disposing and / or growing a layer of material (e.g., graphene or graphene oxide) constituting the intermediate layer 124 on the first metal layer 122a. For example, the intermediate layer 124 can be disposed on the first metal layer 122a at block 304 by Langmuir-Blodgett (LB) deposition, cationic surfactant-assisted LB deposition, micromechanical exfoliation, electrochemical exfoliation, epitaxial growth, chemical vapor deposition, Brodie-Staudenmaier-Hofmann process (or a modified version thereof), Hummers-Offeman process (or a modified version thereof), electrophoretic deposition, or any combination thereof. As another example, the intermediate layer 124 can be disposed on the first metal layer 122a at block 304 by disposing a sheet of graphene or graphene oxide (pre-fabricated) on the first metal layer 122a. For example, graphene or graphene oxide sheets can be grown on different substrates, and then transferred from the different substrates to the first metal layer 122a. Cold pressing or other suitable heat treatment techniques can be used to seal the edges of the graphene or graphene oxide sheets to the first metal layer 122a. In cases where the composite film has a tubular form (such as device 200), the graphene or graphene oxide sheets can be wound around the first metal layer 122a.

[0039] In some embodiments, disposing the second metal layer 122b on the intermediate layer 124 at block 306 includes disposing and / or growing a layer of material (e.g., pure palladium or a palladium-based alloy) constituting the second metal layer 122b on the intermediate layer 124. For example, the second metal layer 122b can be disposed on the intermediate layer 124 at block 306 by physical vapor deposition (e.g., sputtering or electron beam evaporation), chemical vapor deposition, electroless plating, electroplating, or any combination thereof.

[0040] Figure 4 This is a flowchart of an exemplary method 400 for separating hydrogen from a gas stream. Any of composite membrane 100A, composite membrane 100B, or device 200 may, for example, implement method 400. At block 402, a gas stream (e.g., gas stream 202) is brought into contact with the surface of a composite membrane (e.g., composite membrane 100A, composite membrane 100B, or device 200). As previously described, gas stream 202 contains hydrogen molecules, and the composite membrane comprises a porous substrate (e.g., porous substrate 110) and a multilayer membrane (e.g., multilayer membrane 120). Bringing gas stream 202 into contact with the surface of the composite membrane (100A, 100B, or 200) at block 402 may, for example, allow gas stream 202 to flow over the outer surface of the composite membrane (100A, 100B, or 200). For example, gas stream 202 may flow over the outer peripheral surface of the second metal layer 122b of multilayer membrane 120. At frame 404, a composite membrane (100A, 100B, or 200) separates at least a portion of hydrogen molecules from the gas stream 202. Separating at least a portion of hydrogen molecules from the gas stream 202 at frame 404 includes frames 404a and 404b. At frame 404a, in response to contact with the gas stream 202 at frame 402, a multilayer membrane 120 splits at least a portion of the hydrogen molecules into hydrogen atoms and / or protons. At frame 404b, the multilayer membrane 120 prevents the passage of compounds larger than hydrogen molecules that may be present in the gas stream 202, while allowing hydrogen atoms and / or protons (generated by the splitting of one or more hydrogen molecules) to pass through the multilayer membrane 120. After the hydrogen atoms and / or protons have passed through the multilayer membrane 120, the hydrogen atoms and / or protons recombine to reform one or more hydrogen molecules, which subsequently diffuse through the porous substrate 110. In some embodiments, one or more hydrogen molecules (such as hydrogen molecule 202a) that have been separated from the gas stream 202 flow into and pass through the internal pores defined by the porous substrate 110.

[0041] Example

[0042] Figure 5A This is a schematic diagram of a desktop-scale prototype, which includes a reactor comprising a composite membrane for separating hydrogen from a gas stream. Figure 5BA cross-sectional view of the desktop-scale prototype is shown. The operating temperature for experiments on the prototype ranged from 550 °C to 600 °C. The operating pressure for experiments on the prototype ranged from 9 bar to 30 bar. The feed gas stream to the prototype contained a mixture of compounds such as methane, carbon monoxide, carbon dioxide, hydrogen, water (steam), or any combination thereof. Table 1 provides some exemplary feed compositions of the tested gas streams. The feed gas stream contacted the catalyst bed and underwent a chemical reaction (such as steam reforming). The hydrogen formed (along with the hydrogen already present in the feed gas stream) passed through the tubular membrane and entered the inner pores of the tubular membrane. Permeate consisted of hydrogen that passed through the tubular membrane and exited the prototype. Compounds larger than hydrogen were prevented from passing through the tubular membrane and were retained in the annular space defined between the tubular membrane and the reactor wall. The remaining compounds from the feed gas (including reaction products, but excluding hydrogen) passed through the quartz wool barrier and exited the prototype as permeate. The thickness of the tubular membrane (excluding the support) ranges from 5 μm to 8 μm. The metal layer of the prototype is made of an alloy containing palladium and gold. The gold content of this palladium-gold alloy ranges from 20% to 30% by weight.

[0043]

[0044] Table 1: Composition of Experimental Gas Stream Feed

[0045] Figure 5C This is plot 500C showing the hydrogen and nitrogen fluxes over time through a tubular membrane using a desktop-scale prototype. The durations shown in plot 500C are the durations used for annealing the tubular membrane at a hydrogen pressure of 31 bar and an annealing temperature of 550 °C. Nitrogen flux was measured at 5 bar. Figure 5D This is a plot 500D showing the hydrogen flux over time through a tubular membrane in a desktop-scale prototype. The hydrogen flux was measured periodically throughout the experiment while maintaining an operating temperature of 450 °C and an operating pressure of 1.5 bar.

[0046] The desktop-scale prototype is 5 cm long and has a surface area of ​​15 cm². 2This desktop-scale prototype is designed for catalyst testing using liquid or gaseous hydrocarbon feedstocks (5-50 cubic centimeter loadings) that react with water vapor as an oxidant. It allows for membrane performance evaluation in separation mode or using membranes and catalysts packed in a single reactor. Equipped with six mass flow controllers (one each for hydrogen, carbon monoxide, carbon dioxide, methane, nitrogen, and air), it enables evaluation of membrane performance across a wide range of feed compositions. The prototype features three liquid feedstocks using high-pressure pumps. Designed for 50 bar and 1050 °C, it allows for a wide range of operating conditions for testing various reforming reactions and process configurations. The prototype includes a gas-liquid separator and cooler loop to separate the liquids before analyzing the gases using an online residual gas analyzer gas chromatograph (RGA GC). The RGA GC is equipped with a flame ionization detector (FID) and two thermal conductivity detectors (TCDs). This desktop-scale prototype is equipped with a programmable logic controller (PLC)-based control system that operates automatically with interlocks and safety measures in place to prevent gas leaks, such as hydrogen and carbon monoxide. Similar to the laboratory-scale prototype, this desktop-scale prototype has a closed end. Unlike the laboratory-scale prototype, this desktop-scale prototype has a flanged open end, opposite to the closed end. The desktop-scale prototype is housed within a conduit (not shown) through which a hydrogen-containing gas stream flows. During experiments, the flanged open end of the desktop-scale prototype is flanged to a separate outlet conduit (not shown) to receive hydrogen separated from the gas stream flowing over the outer surface of the desktop-scale prototype.

[0047] The pilot-scale prototype has multiple units with a length of 80-90 cm and a surface area of ​​361 cm². 2The pilot-scale prototype comprises 40 tubular membranes packed into a reactor with a loading capacity of 20 kg / day. A steam reforming catalyst is loaded into the reactor along with the 40 tubular membranes. The gas stream fed into the reactor contains natural gas and steam for hydrogen production. Similar to the laboratory-scale and benchtop-scale prototypes, each tubular membrane in this pilot-scale prototype has a closed end and an open end opposite the closed end. The tubular membranes in this pilot-scale prototype are positioned within conduits (not shown) through which the hydrogen-containing gas stream flows. During experiments, the open ends of the tubular membranes in this pilot-scale prototype are coupled to separate outlet conduits (not shown) to receive hydrogen separated from the gas stream flowing over the outer surface of the tubular membranes in the pilot-scale prototype. These separate outlet conduits (not shown) are connected to a manifold for combining the hydrogen separated from the gas stream by the individual tubular membranes in the pilot-scale prototype. At 550 °C and an initial hydrogen feed pressure of 8 bar, the hydrogen flux through the tubular membrane of this pilot prototype was measured to be 7.2 standard cubic meters per hour per square meter (Nm³). 3 / hr / m 2 ).

[0048] While this specification contains many specific details of implementation, these should not be construed as limiting the scope of the claims, but rather as descriptions of features that may be characteristic of particular embodiments. Certain features described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, multiple features described in a single embodiment may also be implemented individually or in any sub-combination in multiple embodiments. Furthermore, although previously described features may be described as operating in certain combinations, and even initially claimed in this manner, in some cases, one or more features from the claimed combination may be removed from that combination, and the claimed combination may involve sub-combinations or variations thereof.

[0049] Unless the context clearly specifies otherwise, as used in this disclosure, the terms "a," "an," or "the" are used to include one or more species. Unless otherwise stated, the term "or" is used to mean a non-exclusive "or." The statement "at least one of A and B" has the same meaning as "A, B, or A and B." Furthermore, it should be understood that the wording or terms used in this disclosure unless otherwise defined are for descriptive purposes only and not for limiting purposes. The use of any section headings is intended to aid in reading this document and should not be construed as limiting; information relating to a section heading may appear within or outside that particular section.

[0050] As used in this disclosure, the terms “about” or “approximately” may allow for a degree of variation in the value or range, for example, within 10%, 5%, or 1% of the value or range limit.

[0051] As used in this disclosure, the term “substantially” means the majority or most, such as at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more.

[0052] Values ​​expressed as ranges should be interpreted flexibly to include not only the values ​​explicitly listed as limits of the range, but also all individual values ​​or subranges covered within that range, as if each value and subrange were explicitly listed. For example, a range of “0.1% to about 5%” or “0.1% to 5%” should be interpreted to include about 0.1% to about 5%, as well as individual values ​​(e.g., 1%, 2%, 3%, and 4%) and subranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within that specified range. Unless otherwise stated, the statement “X to Y” has the same meaning as “about X to about Y”. Similarly, unless otherwise stated, the statement “X, Y, or Z” has the same meaning as “about X, about Y, or about Z”.

[0053] A particular embodiment of the subject matter has been described. Other embodiments, variations, and combinations thereof are within the scope of the appended claims and will be apparent to those skilled in the art. Although operations are described in a specific order in the drawings or claims, this should not be construed as requiring that such operations must be performed in the specific order shown or in a sequential order, or that all illustrated operations must be performed (some operations may be considered optional) to obtain the desired result. In some cases, multitasking or parallel processing (or a combination of multitasking and parallel processing) may be advantageous and may be implemented as appropriate, depending on the circumstances.

[0054] Furthermore, the separation or integration of various system modules and components in the previously described embodiments should not be construed as requiring separation or integration in all embodiments, and it should be understood that the described components and systems can generally be integrated together or packaged into multiple products.

[0055] Therefore, the exemplary embodiments described above do not limit or restrict this disclosure. Other changes, substitutions, and modifications are possible without departing from the spirit and scope of this disclosure.

Claims

1. An apparatus for separating hydrogen molecules from a gas stream, the apparatus comprising: A porous substrate having a pore structure configured to allow hydrogen molecules to diffuse through the porous substrate; and A multilayer film disposed on the surface of the porous substrate, wherein the multilayer film is configured to split hydrogen molecules into at least one of hydrogen atoms or protons in response to contact with hydrogen molecules present in the gas flow, wherein the multilayer film is configured to allow hydrogen atoms or protons to pass through the multilayer film while blocking compounds larger than hydrogen molecules that may be present in the gas flow, wherein the hydrogen atoms or protons recombine to reform hydrogen molecules after passing through the multilayer film, wherein the multilayer film comprises: The first metal layer contains palladium; A second metal layer containing palladium; and An intermediate layer is disposed between the first metal layer and the second metal layer, wherein the intermediate layer comprises at least one of graphene or graphene oxide.

2. The apparatus of claim 1, wherein the porous substrate is metallic, and the multilayer film is coupled to the surface of the porous substrate via an interlayer comprising at least one of alumina, zirconium oxide, cerium oxide, or silicon oxide.

3. The apparatus of claim 1, wherein the first metal layer is made of a first alloy comprising at least one of gold, silver, yttrium, copper, platinum or ruthenium and palladium, and the second metal layer is made of a second alloy comprising at least one of gold, silver, yttrium, copper, platinum or ruthenium and palladium.

4. The apparatus of claim 3, wherein the thickness of each of the first metal layer and the second metal layer is in the range of about 1 micrometer (μm) to about 2 μm.

5. The apparatus of claim 3, wherein the thickness of the multilayer film is in the range of about 3 micrometers (μm) to about 10 μm.

6. The apparatus of claim 3, wherein the porous substrate and the multilayer film are in the form of a tube, the second metal layer is the outermost layer of the tube, and the porous substrate is the innermost layer of the tube.

7. A method for preparing a composite membrane for separating hydrogen molecules from a gas stream, the method comprising: A first metal layer is disposed on a porous substrate, wherein the porous substrate has a pore structure configured to allow hydrogen molecules to diffuse through the porous substrate, and the first metal layer comprises palladium; An intermediate layer is disposed on the first metal layer, wherein the intermediate layer comprises at least one of graphene or graphene oxide; A second metal layer is disposed on the intermediate layer, wherein the first metal layer, the intermediate layer, the second metal layer, and the porous substrate form the composite film, and the second metal layer comprises palladium; and The composite film is heat-treated to make its thickness and composition uniform.

8. The method of claim 7, wherein the porous substrate is metallic, the method further comprising disposing a sandwich layer on the porous substrate prior to disposing the first metal layer, the sandwich layer comprising at least one of alumina, zirconium oxide, cerium oxide, or silicon oxide, and disposing the first metal layer on the porous substrate comprising disposing the first metal layer on the sandwich layer already disposed on the porous substrate.

9. The method of claim 7, wherein the first metal layer is made of a first alloy comprising at least one of gold, silver, yttrium, copper, platinum or ruthenium and palladium, and the second metal layer is made of a second alloy comprising at least one of gold, silver, yttrium, copper, platinum or ruthenium and palladium.

10. The method of claim 9, wherein the thickness of each of the first metal layer and the second metal layer is in the range of about 1 micrometer (μm) to about 2 μm.

11. The method of claim 9, wherein the thickness of the multilayer film is in the range of about 3 micrometers (μm) to about 10 μm.

12. The method of claim 9, wherein the porous substrate and the multilayer film are in the form of a tube, the second metal layer is the outermost layer of the tube, and the porous substrate is the innermost layer of the tube.

13. A method comprising: A gas stream containing hydrogen molecules is brought into contact with the surface of a composite membrane, the composite membrane comprising a porous substrate and a multilayer membrane, wherein the multilayer membrane comprises a first metal layer containing palladium, an intermediate layer containing at least one of graphene or graphene oxide, and a second metal layer containing palladium. as well as At least a portion of the hydrogen molecules are separated from the gas stream through the composite membrane, wherein separating at least a portion of the hydrogen molecules from the gas stream comprises: In response to contact with the gas flow, at least a portion of the hydrogen molecules are split into at least one of hydrogen atoms or protons through the multilayer film; as well as The multilayer membrane prevents compounds larger than hydrogen molecules that may be present in the gas flow from passing through, while allowing hydrogen atoms or protons to pass through the multilayer membrane.

14. The method of claim 13, wherein the porous substrate is metallic, and the multilayer film is coupled to the surface of the porous substrate through an interlayer comprising at least one of alumina, zirconium oxide, cerium oxide, or silicon oxide.

15. The method of claim 13, wherein the first metal layer is made of a first alloy comprising at least one of gold, silver, yttrium, copper, platinum or ruthenium and palladium, and the second metal layer is made of a second alloy comprising at least one of gold, silver, yttrium, copper, platinum or ruthenium and palladium.

16. The method of claim 15, wherein the thickness of each of the first metal layer and the second metal layer is in the range of about 1 micrometer (μm) to about 2 μm.

17. The method of claim 15, wherein the thickness of the multilayer film is in the range of about 3 micrometers (μm) to about 10 μm.

18. The method of claim 15, wherein the porous substrate and the multilayer film are in the form of a tube, the second metal layer is the outermost layer of the tube, and the porous substrate is the innermost layer of the tube.

19. The method of claim 18, wherein contacting the gas flow with the surface of the composite membrane comprises flowing the gas flow over the outer peripheral surface of the second metal layer.

20. The method of claim 19, wherein hydrogen molecules separated from the gas stream flow into and through the internal pores defined by the porous substrate.

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