Composite palladium-based alloy material, method for its production and use

Abstract

The present application relates to the field of palladium-based alloy material, discloses a composite palladium-based alloy material and its preparation method and purposes.The composite palladium-based alloy material contains Pd and IB group metal element and the molar ratio of Pd and IB group metal element is 1: (0.01-10), and the half-peak width of at least one characteristic peak in the XRD pattern of the composite palladium-based alloy material in the range of 5°-90° is less than or equal to 0.1745.The composite palladium-based alloy material used in the present application has lower hydrogen permeation activation energy, higher hydrogen permeation efficiency, stability and carbon deposition resistance, and has a longer service life when used as a composite membrane (especially in water vapor reforming hydrogen production).

Description

Technical Field

[0001] This invention relates to the field of palladium-based alloy materials, specifically to a composite palladium-based alloy material, its preparation method, and its applications. Background Technology

[0002] Methanol steam reforming for hydrogen production has become a hot topic among researchers due to the wide availability and convenient storage and transportation of methanol, its high hydrogen storage capacity per unit mass of methanol, and its low reaction temperature. Currently, research on catalysts for methanol steam reforming for hydrogen production is becoming increasingly mature, with the CuO / ZnO / Al2O3 catalyst being the most representative, suitable for reaction temperatures of 150-350℃. Since the methanol conversion rate is difficult to achieve 100%, and the target product H2 inevitably contains components such as CO, CO2, and H2O, subsequent separation and purification are particularly important. Currently, relatively mature hydrogen separation processes include cryogenic separation, pressure swing adsorption (PSA), and membrane separation. Among these, membrane separation has the advantages of quiet operation (noise level typically 30-40 dB) and compactness, making it particularly suitable for small- to medium-scale applications with high hydrogen purity requirements, such as in the electronics and semiconductor fields. In membrane separation processes, palladium and its alloy membranes exhibit selective permeability to hydrogen based on the dissolution-diffusion principle. Dense membrane materials can intercept other impurity gases, theoretically achieving 100% purity hydrogen separation and purification. Therefore, it is an ideal product separation method. For example, CN108686522A discloses the application of a high-temperature resistant palladium alloy composite membrane in steam reforming for hydrogen production, applying a 1-10 μm thick palladium alloy composite membrane loaded on a tubular ceramic support to the steam reforming hydrogen production reaction. However, the application of palladium membranes in methanol steam reforming systems faces the following problems that urgently need to be addressed: 1) After hydrogen dissolution at low temperatures (<573 K), the ultrathin palladium membrane is prone to hydrogen embrittlement and cracking due to drastic changes in lattice parameters. 2) As the reaction proceeds, carbon deposition on the palladium membrane surface increases the hydrogen permeation activation energy, reducing the hydrogen permeation and diffusion rate, and affecting the product separation and purification efficiency. 3) Direct contact between the non-precious metal catalyst and the precious metal palladium membrane material easily reduces the hydrogen permeation and diffusion rate and catalytic activity due to the interaction between the two materials. 4) Due to differences in raw material sources, sulfur-containing compounds may be mixed into the reaction system. Trace amounts of hydrogen sulfide, methyl sulfide, and other sulfur-containing compounds are more easily adsorbed and accumulated on the palladium membrane surface than hydrogen. Long-term exposure of the palladium membrane to a sulfur-containing atmosphere can easily lead to poisoning and the formation of palladium sulfide (Pd4S), thus affecting the hydrogen permeation and diffusion efficiency. Current technologies have not yet made breakthrough progress in addressing the sulfur resistance problem of the palladium membrane. 5) The methanol steam reforming hydrogen production process inevitably produces a large amount of carbon dioxide. The greenhouse effect and other environmental problems caused by carbon dioxide emissions will restrict the further development of this process. Therefore, how to achieve the comprehensive utilization of carbon dioxide capture, conversion, etc., through the structural design of the membrane reactor, and ultimately achieve the goal of "zero carbon emissions," is a challenge facing this system. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems existing in the prior art and to provide a composite palladium-based alloy material, its preparation method, and its uses.

[0004] To achieve the above objectives, the present invention provides a composite palladium-based alloy material containing Pd and Group IB metal elements with a molar ratio of Pd to Group IB metal elements of 1:(0.01-10), wherein the full width at half maximum (FWHM) of at least one characteristic peak of 2θ in the range of 5°-90° in the XRD pattern of the composite palladium-based alloy material is less than or equal to 0.1745.

[0005] The second aspect of the present invention provides a method for preparing a composite palladium-based alloy material, the method comprising: depositing Pd and a Group IB metal on a support, and then alloying the support on which Pd and the Group IB metal were deposited, wherein the molar ratio of Pd to the Group IB metal is 1:(0.01-10).

[0006] The alloying process is as follows: in an activating atmosphere, the temperature is first heat-treated at a temperature above 350°C, and then cooled to below 200°C at a rate of more than 5°C / min. The gas providing the activating atmosphere may optionally include an alkaline gas.

[0007] The third aspect of the present invention provides a composite palladium-based alloy material prepared by the method described in the second aspect.

[0008] A fourth aspect of the present invention provides a composite membrane comprising a composite palladium-based alloy material and a silicon-aluminum molecular sieve modified with hydrophobic groups attached to the surface of the composite palladium-based alloy material, wherein the composite palladium-based alloy material is the composite palladium-based alloy material as described above.

[0009] The fifth aspect of the present invention provides the application of the composite membrane described above in steam reforming for hydrogen production.

[0010] A sixth aspect of the present invention provides a method for producing hydrogen by steam reforming, the method comprising:

[0011] In the presence of a catalyst, alcohol and water vapor are introduced into a first reactor equipped with a first composite membrane for a reforming reaction, wherein the first composite membrane is a composite membrane as described above; the alcohol and water vapor are introduced from the side of the silica-alumina molecular sieve modified with hydrophobic groups near the first composite membrane, so that the hydrogen gas generated by the reforming reaction passes through the first composite membrane via the side of the silica-alumina molecular sieve modified with hydrophobic groups and is removed from the first reactor.

[0012] Through the above technical solution, the present invention, after heat treatment at a specific temperature and cooling at a specific rate, can reduce the activation energy of hydrogen permeation of the membrane material, thereby improving the hydrogen permeation efficiency and stability of the membrane material; on the other hand, it can improve the anti-carbon deposition ability of the composite membrane, thereby further extending the service life of the composite membrane; furthermore, the use of the composite membrane of the present invention in steam reforming hydrogen production can ensure the catalytic activity of the catalyst and the mechanical integrity of the composite palladium-based alloy material.

[0013] According to a preferred embodiment of the present invention, by using a molecular sieve as a protective layer for the composite palladium-based alloy material, the resulting composite membrane has a high hydrogen permeation diffusion rate, and the non-precious metal catalyst and the precious metal palladium membrane material do not come into direct contact, so the hydrogen permeation diffusion rate and the catalytic activity of the catalyst are less likely to be affected and remain stable.

[0014] According to another preferred embodiment of the present invention, the hydrophobically treated composite membrane exhibits stronger resistance to sulfur and carbon deposition, lower hydrogen permeation activation energy, and a longer service life. Furthermore, the sulfur-resistant metal oxide nanoparticles on the molecular sieve surface can activate and decompose sulfur-containing compounds, further enhancing the sulfur resistance of the composite membrane.

[0015] According to another preferred embodiment of the present invention, the composite membrane of the present invention is combined with another palladium membrane to capture or convert carbon dioxide obtained from steam reforming for hydrogen production, thereby converting carbon dioxide into high value-added products, improving the comprehensive utilization rate of carbon dioxide and alleviating the environmental problems caused by carbon dioxide. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of hydrogen production from alcohol steam reforming using a hydrophobically treated ZSM-5 / PdAu composite membrane.

[0017] Figures 2a-2c These are the XRD characteristic spectra of composite palladium-based alloy materials and molecular sieve structures;

[0018] Figure 3 These are experimental diagrams showing the contact angles of the composite membrane with different liquids before hydrophobic treatment.

[0019] Figure 4 These are experimental diagrams showing the contact angles of the hydrophobic composite membrane with different liquids.

[0020] Figure 5 These are the infrared characterization results of hydroxyl groups before and after hydrophobic treatment;

[0021] Figure 6 These are the results of nuclear magnetic resonance characterization before and after hydrophobic treatment;

[0022] Figure 7 This is a scanning electron microscope (SEM) image of the composite film surface after loading MoO2 nanoparticles;

[0023] Figure 8 This is a schematic diagram of a structure in which the catalyst and composite membrane are encapsulated and placed in a tubular reactor. Detailed Implementation

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] The present invention provides a composite palladium-based alloy material, characterized in that the composite palladium-based alloy material contains Pd and Group IB metal elements and the molar ratio of Pd and Group IB metal elements is 1:(0.01-10), and the full width at half maximum (FWHM) of at least one characteristic peak of 2θ in the range of 5°-90° in the XRD pattern of the composite palladium-based alloy material is less than or equal to 0.1745.

[0026] In this invention, the crystal structure of the composite palladium-based alloy material is either face-centered cubic close-packed (FCC) or body-centered cubic (BCC). "Face-centered cubic close-packed" means that the 14 atoms in one unit cell belong to four layers: layer A is a vertex, the three adjacent face-centered atoms and three vertex atoms belong to layer B, the next six atoms belong to layer C, and one vertex, opposite to the vertex of layer A, belongs to layer A in the next cycle. "Body-centered cubic" refers to a close-packed arrangement in a cubic crystal system, containing two lattice points, one at a vertex and one at the body center. That is, eight atoms are located at the eight vertices of the cube, and one atom is located at the center of the cube, with the eight vertices tangent to the central atom.

[0027] In this invention, the lattice parameter k of the composite palladium-based alloy material is 0.3836-0.4369 nm, preferably 0.4075-0.4289 nm. "Lattice parameter k" refers to the physical size of the unit cell in the crystal lattice, representing the basic structural parameter of the crystalline material. The lattice parameter k represents the edge length of the unit cell, that is, the edge length of each parallelepiped unit, and it is directly related to the bonding energy between atoms. A unit cell in three-dimensional space generally has three lattice parameters, denoted by a, b, and c. According to the morphological distribution of the Bravais lattice, in the cubic crystal structure involved in this invention, these three constants are all equal, and therefore can be represented by parameter k. Changes in k reflect changes in the composition, stress state, etc., within the crystal. The lattice parameter k can be determined using X-ray diffraction (XRD) or atomic force microscopy (AFM).

[0028] According to a preferred embodiment of the present invention, the full width at half maximum (FWHM) of all characteristic peaks of 2θ in the range of 5°-90° in the XRD pattern of the composite palladium-based alloy material is less than or equal to 0.1745, more preferably less than or equal to 0.084, 0.078, 0.072, 0.069, 0.064, 0.055, or 0.039, typically greater than or equal to 0.01, 0.017, 0.029, 0.031, 0.032, 0.052, 0.059, 0.062, 0.068, or 0.073, and even more preferably greater than or equal to 0.017.

[0029] More preferably, when the composite palladium-based alloy material has a face-centered cubic close-packed structure, the full width at half maximum (FWHM) of the characteristic peak at 2θ = 40° ± 1° (i.e., the characteristic peak of crystal plane (110)) in its XRD pattern is less than or equal to 0.0555 or less than or equal to 0.0198, or the full width at half maximum (FWHM) of the characteristic peak at 2θ = 46° ± 1° (i.e., the characteristic peak of crystal plane (111)) is less than or equal to 0.0699 or less than or equal to 0.0332, or the full width at half maximum (FWHM) of the characteristic peak at 2θ = 46° ± 1° ... The full width at half maximum (FWHM) of the characteristic peak at 69°±1° (i.e., the characteristic peak of crystal plane (220)) is less than or equal to 0.0873 or less than or equal to 0.0352, or the full width at half maximum (FWHM) of the characteristic peak at 2θ=83°±1° (i.e., the characteristic peak of crystal plane (311)) is less than or equal to 0.1047 or less than or equal to 0.039, or the full width at half maximum (FWHM) of the characteristic peak at 2θ=87°±1° (i.e., the characteristic peak of crystal plane (222)) is less than or equal to 0.1396 or less than or equal to 0.0402. Furthermore, in the XRD pattern of the composite palladium-based alloy material, the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 40° ± 1° is in the range of 0.017-0.02, or the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 46° ± 1° is in the range of 0.017-0.034, or the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 69° ± 1° is in the range of 0.029-0.036, or the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 83° ± 1° is in the range of 0.031-0.039, or the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 87° ± 1° is in the range of 0.032-0.041.

[0030] More preferably, when the composite palladium-based alloy material has a body-centered cubic structure, the full width at half maximum (FWHM) of the characteristic peak at 2θ = 43° ± 1° (i.e., the characteristic peak of crystal plane (110)) in its XRD pattern is less than or equal to 0.0722 or less than or equal to 0.058, or the full width at half maximum (FWHM) of the characteristic peak at 2θ = 53° ± 1° (i.e., the characteristic peak of crystal plane (111)) is less than or equal to 0.0873 or less than or equal to 0.073, or the full width at half maximum (FWHM) of the characteristic peak at 2θ = 62° ± 1° is less than or equal to 0.073 or less than or equal to 0.073. The full width at half maximum (FWHM) of the characteristic peak at 2θ = 70° ± 1° (i.e., the characteristic peak of crystal plane (200)) is less than or equal to 0.0873 or less than or equal to 0.086, or the full width at half maximum (FWHM) of the characteristic peak at 2θ = 70° ± 1° (i.e., the characteristic peak of crystal plane (210)) is less than or equal to 0.1047 or less than or equal to 0.088, or the full width at half maximum (FWHM) of the characteristic peak at 2θ = 79° ± 1° (i.e., the characteristic peak of crystal plane (211)) is less than or equal to 0.1571 or less than or equal to 0.103. Furthermore, in the XRD pattern of the composite palladium-based alloy material, the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 43° ± 1° is in the range of 0.017-0.041, or the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 53° ± 1° is in the range of 0.024-0.055, or the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 62° ± 1° is in the range of 0.036-0.066, or the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 70° ± 1° is in the range of 0.047-0.068, or the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 79° ± 1° is in the range of 0.051-0.074. The "half-maximum width" is defined as the width of the peak at half its height, i.e., the half-height width. The half-height width is converted to radians according to the Debye-Scherrer formula (D = Kγ / Bcosθ), and the radian value characterizes the size of the half-maximum width. When the composite palladium-based alloy material has no characteristic peak at the corresponding 2θ, the half-peak width is considered to be 0.

[0031] According to the composite palladium-based alloy material of the present invention, the Group IB metal element can improve the permeation and diffusion properties of the obtained composite palladium-based alloy material, such as hydrogen solubility and diffusion coefficient, and can be at least one of Cu, Ag and Au, but preferably Au.

[0032] According to the composite palladium-based alloy material of the present invention, the Group IB metal element is Au, and in the XRD pattern of the composite palladium-based alloy material, the half-width at half-maximum (FWHM1) of the characteristic peak at 2θ = 40° ± 1°, the half-width at half-maximum (FWHM2) of the characteristic peak at 2θ = 46° ± 1°, the half-width at half-maximum (FWHM3) of the characteristic peak at 2θ = 69° ± 1°, the half-width at half-maximum (FWHM4) of the characteristic peak at 2θ = 83° ± 1°, and the half-width at half-maximum (FWHM5) of the characteristic peak at 2θ = 87° ± 1° satisfy the following formula I:

[0033] FWHM x =(FWHM) x-1 +FWHMx+1 ) / 2±W Formula I

[0034] Where x = 2, 3, or 4, and W is 0.0003-0.0064. Composite palladium-based alloys with a full width at half maximum (FWHM) of the characteristic peak satisfying Equation I exhibit superior hydrogen permeability and stability.

[0035] The composite palladium-based alloy material according to the present invention may also contain Ni. Preferably, the molar ratio of Pd to Ni is 1:(0.35-0.65).

[0036] According to the composite palladium-based alloy material of the present invention, the composite palladium-based alloy material is a film-like material. The thickness of the composite palladium-based alloy material can be 0.5-30 μm, preferably 5-15 μm.

[0037] According to one embodiment of the present invention, the composite palladium-based alloy material may be the composite palladium-based alloy material E described later.

[0038] The inventors of this invention discovered in their research that alloying in a specific manner is particularly beneficial for improving the hydrogen permeability and stability of the resulting composite palladium-based alloy material. Therefore, this invention also provides a method for preparing a composite palladium-based alloy material, characterized in that the method includes: depositing Pd, a Group IB metal, and optionally Ni on a support, and then alloying the support on which Pd, Group IB metal, and optionally Ni have been deposited, wherein the molar ratio of Pd to Group IB metal is 1:(0.01-10), preferably 1:(0.1-1.6), and more preferably 1:(0.2-0.8);

[0039] The alloying treatment is performed as follows: in an activating atmosphere, the temperature is first increased to above 350°C (e.g., 500°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C or any value between the above values), and then the temperature is decreased to below 200°C at a rate greater than 5°C / min (e.g., 30, 35, 40, 45, 55, 65, 70, 80, 100°C / min or any value between the above values). The gas providing the activating atmosphere optionally includes an alkaline gas.

[0040] In this invention, the molar ratio of Group IB metal elements (or Group IB metals) to Pd can be 0.05, 0.1, 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 3, 5, 8, 9 or any value between the above values, preferably 0.1-1.6, more preferably 0.2-0.8.

[0041] In this invention, the molar ratio of Ni to Pd is preferably 0.35-0.65, such as 0.4, 0.45, 0.5, 0.55, 0.58, 0.6, 0.62 or any value between the above values.

[0042] In this invention, the Group IB metal can be at least one of Cu, Ag and Au, but is preferably Au.

[0043] In a preferred embodiment of the present invention, the alloying treatment is performed as follows: the material is treated in an activating atmosphere at a temperature of 350-650°C and a pressure of 0.12-0.75 MPa for 2-10 hours; then cooled to 100-200°C at a rate of 25-150°C / min. The composite palladium-based alloy material obtained according to this preferred embodiment exhibits higher hydrogen permeability or stability.

[0044] In this invention, the gas providing the activating atmosphere can be any common gaseous gas in the art that is in a gaseous state under alloying conditions. Preferably, the activating atmosphere is provided by at least one of rare gases (such as Ar), N2, water vapor, H2, acidic gases (such as CO2), and basic gases (such as ethylenediamine and NH3, PH3, N2H4). According to a preferred embodiment of the invention, the gas providing the activating atmosphere includes hydrogen and nitrogen, wherein the hydrogen content in the mixture of hydrogen and nitrogen is greater than or equal to 30% by volume, more preferably 35-70% by volume. The addition of a basic gas enables faster activation of the palladium-based alloy film, resulting in a more stable face-centered cubic structure and a smaller full width at half maximum (FWHM) of the characteristic peaks in the XRD pattern. Therefore, preferably, the gas providing the activating atmosphere includes a basic gas.

[0045] According to a preferred embodiment of the present invention, the gas providing the activating atmosphere includes hydrogen and an alkaline gas. More preferably, the content of the alkaline gas in the gas providing the activating atmosphere is greater than or equal to 20% by volume, such as 22% by volume, 25% by volume, 28% by volume, 30% by volume, 40% by volume, 50% by volume, or any value between the above values, more preferably greater than or equal to 30% by volume. Similar effects can be obtained by providing an activating atmosphere consisting solely of an alkaline gas.

[0046] More preferably, the alkaline gas is selected from at least one of ethylenediamine, NH3, PH3 (phosphine) and N2H4 (hydrazine).

[0047] In this invention, the pressure of the alloying process is generally controlled by adjusting the amount of gas used to provide the activating atmosphere. After being cooled to below 200°C at a specific rate, it can be cooled to room temperature for later use.

[0048] In a preferred embodiment of the present invention, the total thickness of Pd and Group IB metals deposited on the support is 0.5-30 μm, preferably 5-15 μm.

[0049] In a preferred embodiment of the present invention, the thickness of the support is 0.1-20 mm, preferably 2-5 mm. The support can be provided by materials commonly used in the art that can withstand the operating temperature of the present invention without affecting hydrogen permeability, that is, materials that do not deform or affect hydrogen permeability at the operating temperature of the present invention. To ensure excellent hydrogen permeability and to obtain better mechanical and thermal stability, as well as reduce the amount of palladium used (reducing costs), the support is preferably a porous support, selected from at least one of porous ceramics, porous glass, porous metals (such as porous stainless steel), porous quartz, and polymers, more preferably from at least one of porous ceramics, porous metals, and polymers. Generally, the porosity of the support ranges from 15-75%, and the average pore size is 0.05-0.4 μm. To obtain a tubular membrane, the support is preferably a tubular support. The porous ceramic material can be γ-Al₂O₃, with a porosity range of 25-66% and an average pore size of 0.12-0.4 μm. Porous stainless steel can be made of 316L (Fe) 69 Cr 17 Ni 12 Mo2 has a porosity ranging from 32% to 71% and an average pore size of 0.08 to 0.36 μm. The polymer material can be polyimide, with a porosity ranging from 15% to 37% and an average pore size of 0.05 to 0.22 μm. The "porosity range" and "average pore size" can both be determined using nitrogen physical adsorption.

[0050] The present invention also provides a composite palladium-based alloy material prepared by the method described above.

[0051] The present invention further provides a composite membrane, characterized in that the composite membrane comprises a composite palladium-based alloy material and a silicon-aluminum molecular sieve modified with hydrophobic groups attached to the surface of the composite palladium-based alloy material, wherein the composite palladium-based alloy material is the composite palladium-based alloy material as described above, or a composite palladium-based alloy material prepared by the method described above.

[0052] According to the composite membrane of the present invention, the water contact angle of the composite membrane is preferably greater than or equal to 90°, more preferably greater than or equal to 105°.

[0053] According to the composite membrane of the present invention, the composite membrane is preferably a tubular membrane.

[0054] According to the composite membrane of the present invention, the composite membrane further includes a support body, on which the composite palladium-based alloy material is attached. The thickness and type of the support body are as described above and will not be repeated here.

[0055] According to the composite membrane of the present invention, preferably, the hydrophobic group-modified silica-alumina molecular sieve... 29 In the Si MAS NMR spectrum, the peak area ratio (Q4 / Q3) of the peaks with chemical shifts near -113 ppm and -103 ppm is 6-12.

[0056] According to the composite membrane of the present invention, the hydrophobic groups in the hydrophobic group-modified silica-alumina molecular sieve can be provided by commonly used substances that are attached to the molecular sieve by electrostatic adsorption or coordination bonds to improve the hydrophobicity of the molecular sieve. For example, they can be provided by at least one of polymethylhydrosiloxane, vinyltriethoxysilane, 3-aminopropyltriethylsilane, N,N-diethyltrimethylsilane, 3-aminopropyltrimethoxysilane, (3-mercaptopropyl)trimethoxysilane, 3-aminopropyltriethoxysilane, N,N-diethyl-3-(trimethoxysilyl)propylamine, 1-[3-(trimethoxysilyl)propyl]urea, (3-chloropropyl)trimethoxysilane, and 3-chloropropyltriethoxysilane, preferably at least one of polymethylhydrosiloxane, vinyltriethoxysilane, 3-aminopropyltriethylsilane, N,N-diethyltrimethylsilane, and 3-aminopropyltrimethoxysilane.

[0057] According to the composite membrane of the present invention, the hydrophobic group-modified silica-alumina molecular sieve is at least one selected from hydrophobic group-modified ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-34, 3A molecular sieve, 4A molecular sieve, 5A molecular sieve, SAPO-31, SAPO-34, SAPO-44, RUB-13, MCM-68, Y-type molecular sieve, and mordenite, more preferably ZSM-5 molecular sieve. The preferred molecular sieve of the present invention, when combined with a composite palladium-based alloy material, can further improve the efficiency of hydrogen production through reforming.

[0058] According to the composite membrane of the present invention, the thickness of the hydrophobic group-modified silica-alumina molecular sieve can be 1-100 μm, preferably 5-30 μm.

[0059] According to the composite membrane of the present invention, the silicon-to-aluminum molar ratio of the hydrophobic group-modified silica-alumina molecular sieve can be (2-100):1, preferably (2.5-20):1. The average particle size of the hydrophobic group-modified silica-alumina molecular sieve can be 60-380 nm, preferably 150-200 nm. The average pore size of the hydrophobic group-modified silica-alumina molecular sieve can be 0.3-230 nm, preferably 1-18 nm. The specific surface area of ​​the hydrophobic group-modified silica-alumina molecular sieve can be 35-750 m². 2 / g, preferably 65-480m 2 / g. The crystallinity of the hydrophobic group-modified silica-alumina molecular sieve can be greater than or equal to 90%, preferably 95-99%.

[0060] According to the composite membrane of the present invention, in order to improve the sulfur resistance of the composite membrane to adapt to hydrogen production from sulfur-containing feedstocks through reforming, the composite membrane may further include VIB metal oxide nanoparticles attached to the surface of a silica-alumina molecular sieve modified with hydrophobic groups. Preferably, the VIB metal is Mo and / or W (or the oxide of the VIB metal is MoO2 and / or WO3), but more preferably Mo (or the oxide of the VIB metal is MoO2). Preferably, the average particle size of the VIB metal oxide nanoparticles is 50-200 nm. Preferably, the content of the VIB metal oxide nanoparticles is such that the molar ratio between the VIB metal and Pd is 0.01-0.5. In a preferred embodiment, as... Figure 1 As shown in Figure 8, the composite membrane includes a support 1, and a composite palladium-based alloy material 2, a hydrophobic group-modified silica-alumina molecular sieve 3, and optional group VIB metal oxide nanoparticles sequentially attached to the support 1. When the composite membrane of the present invention is used for reforming hydrogen production, a catalyst 4 for catalyzing the reforming reaction is further attached, thereby allowing the reforming reaction to occur on the side closer to the catalyst. The generated hydrogen gas passes sequentially through the potentially present group VIB metal oxide nanoparticles, the hydrophobic group-modified silica-alumina molecular sieve 3, the composite palladium-based alloy material 2, and the support 1.

[0061] This invention also relates to a method for preparing a composite membrane, characterized in that the method comprises:

[0062] (1) Pd, Group IB metal and optional Ni are deposited on a support, and then the support with Pd, Group IB metal and optional Ni deposited is alloyed, wherein the molar ratio of Pd to Group IB metal is 1:(0.01-10), preferably 1:(0.1-1.6), more preferably 1:(0.2-0.8);

[0063] The alloying process is as follows: in an activating atmosphere, the temperature is first heat-treated at a temperature above 350°C, and then the temperature is reduced to below 200°C at a rate of more than 5°C / min. The gas providing the activating atmosphere may optionally include an alkaline gas.

[0064] (2) The alloyed material is placed in a solution of a precursor containing silicon-aluminum molecular sieve and subjected to hydrothermal crystallization, drying and calcination in sequence to obtain a composite membrane precursor.

[0065] (3) Modify the composite membrane precursor with hydrophobic groups.

[0066] In the method for preparing composite membranes, the alloying treatment, IB group metals, activation atmosphere, support, etc. in step (1) can be as described above, and will not be repeated here.

[0067] In the method of preparing composite membranes, the precursor solution of silicon-aluminum molecular sieves generally contains silicon source, aluminum source, template agent and water.

[0068] Preferably, the molar ratio of the silicon source, aluminum source, template agent, and water is 100:(1-50):(10-55):(50-2750), more preferably 100:(5-40):(25-50):(75-1500).

[0069] Preferably, the amount of the precursor solution containing silicon-aluminum molecular sieve is 0.05-2 ml relative to 1 g of alloyed material.

[0070] The silicon source can be a common material in the art that can provide silicon. Preferably, the silicon source is at least one of silicate ester, silicate and silicon dioxide, and more preferably at least one of tetrabutyl orthosilicate, tetraethyl orthosilicate, sodium silicate, potassium silicate, silica sol and water glass.

[0071] The aluminum source can be a common substance in the art that can provide aluminum. Preferably, the aluminum source is at least one of aluminate, alumina, aluminum salt, aluminum sol and organic aluminum alkoxide, and more preferably at least one of sodium aluminate, boehmite, aluminum sulfate, aluminum nitrate and aluminum isopropoxide.

[0072] Preferably, the template agent is at least one selected from tetraalkylammonium hydroxide, alkylamine, and tetraalkylammonium halide, and more preferably at least one selected from tetrabutylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium hydroxide, triethylamine, hexadecyltrimethylammonium bromide, and isopropylamine.

[0073] In the method for preparing composite membranes, the hydrothermal crystallization can be performed by first aging and then crystallizing.

[0074] Preferably, the aging conditions include an aging temperature of 60-90°C.

[0075] Preferably, the aging conditions further include an aging time of 3-9 hours.

[0076] Preferably, the crystallization conditions include a crystallization temperature of 150-185°C.

[0077] Preferably, the crystallization conditions further include a crystallization time of 12-72 hours.

[0078] The aging process of the present invention can be carried out under stirring conditions, preferably at a stirring rate of 600-1200 rpm. The crystallization process of the present invention can also be carried out under stirring conditions, preferably at a stirring rate of 15-30 rpm.

[0079] In the method for preparing the composite membrane, there are no special requirements for the drying conditions, which may include: a drying temperature of 50-80℃. The drying conditions may also include: a drying time of 4-18 hours.

[0080] In the method for preparing the composite membrane, preferably, the calcination conditions include: a calcination temperature of 500-650℃. Preferably, the calcination conditions also include: a calcination time of 4-10 hours.

[0081] In the method of preparing the composite membrane, the preferred method of modifying the composite membrane precursor with hydrophobic groups is to silanize the composite membrane precursor with a silanizing agent, which can be carried out by chemical vapor deposition.

[0082] Preferably, the amount of the silanizing agent used is 3-9 ml relative to 1 g of the composite membrane precursor.

[0083] Preferably, the silanizing agent can be selected from substances commonly used in the art that can silanize molecular sieves to improve their hydrophobicity. For example, the silanizing agent is selected from at least one of polymethylhydrosiloxane, vinyltriethoxysilane, 3-aminopropyltriethylsilane, N,N-diethyltrimethylsilane, 3-aminopropyltrimethoxysilane, (3-mercaptopropyl)trimethoxysilane, 3-aminopropyltriethoxysilane, N,N-diethyl-3-(trimethoxysilyl)propylamine, 1-[3-(trimethoxysilyl)propyl]urea, (3-chloropropyl)trimethoxysilane, and 3-chloropropyltriethoxysilane, and is preferably selected from at least one of polymethylhydrosiloxane, vinyltriethoxysilane, 3-aminopropyltriethylsilane, N,N-diethyltrimethylsilane, and 3-aminopropyltrimethoxysilane.

[0084] Preferably, the conditions for silanization treatment may include: a temperature of 15-75℃, preferably 30-55℃; and a pressure of 10-70 kPa. The silanizing agent may be introduced by a purge gas (which may be N2, a rare gas, CO2, etc.), and the flow rate of the purge gas may be 35-75 ml / min.

[0085] In the method for preparing the composite membrane, in order to improve the sulfur resistance of the composite membrane, the method may further include: (4) depositing VIB group metal oxide nanoparticles on the surface of the product modified with hydrophobic groups obtained in step (3).

[0086] Preferably, the group VIB metal is Mo and / or W (or the oxide of the group VIB metal is MoO2 and / or WO3), but more preferably it is Mo (or the oxide of the group VIB metal is MoO2).

[0087] Preferably, the average particle size of the group VIB metal oxide nanoparticles is 50-200 nm.

[0088] Preferably, the deposition amount of the group VIB metal oxide nanoparticles is such that the molar ratio between the group VIB metal and Pd is 0.01-0.5.

[0089] In the method for preparing the composite film, the method of depositing VIB metal oxide nanoparticles is not particularly limited. In-situ synthesis using hydrothermal synthesis can be employed. Specifically, this may include: under hydrothermal synthesis conditions, immersing the hydrophobic group-modified product obtained in step (3) in a solution containing a VIB metal precursor. Preferably, the concentration of the VIB metal element in the VIB metal precursor solution is 0.01-0.55 mol / L. The VIB metal precursor can be selected from molybdates and / or tungstates, preferably at least one of (NH4)6Mo7O2, sodium tungstate, sodium molybdate, potassium molybdate, and strontium molybdate. According to a specific embodiment of the present invention, the VIB metal precursor solution contains (NH4)6Mo7O2, (NH4)2CO3, N2H4, and LiOH in a molar ratio of 1:(1-5):(5-8):(2-5). Preferably, the conditions for the hydrothermal synthesis (impregnation) may include: a temperature of 150-250°C and a time of 24-40 hours.

[0090] The present invention also relates to composite membranes prepared by the method described above.

[0091] The present invention also provides the application of the composite membrane as described above in steam reforming for hydrogen production.

[0092] By using the composite membrane of the present invention, high-purity hydrogen with a purity greater than 99.999% can be obtained. Therefore, the present invention further provides a method for producing hydrogen by steam reforming, characterized in that the method includes:

[0093] In the presence of a catalyst, alcohol and water vapor are introduced into a first reactor equipped with a first composite membrane for a reforming reaction, wherein the first composite membrane is a composite membrane as described above; the alcohol and water vapor are introduced from the side of the silica-alumina molecular sieve modified with hydrophobic groups near the first composite membrane, so that the hydrogen gas generated by the reforming reaction passes through the first composite membrane and is removed from the first reactor via the side of the silica-alumina molecular sieve modified with hydrophobic groups.

[0094] Optionally, the method further includes introducing gas that has not permeated the first composite membrane into a second reactor equipped with a second composite membrane for carbon dioxide capture or conversion.

[0095] In the method of producing hydrogen by steam reforming, the alcohol can be a monohydric alcohol with 1-6 carbon atoms and / or a dihydric alcohol with 1-6 carbon atoms, preferably at least one of methanol, ethanol, ethylene glycol and propanol.

[0096] In the method for producing hydrogen by steam reforming, the catalyst can be a catalyst commonly used in the art for producing hydrogen by steam reforming, for example, at least one of CuO / ZnO / Al2O3, Ru / Al2O3, Cu-Ir / Al2O3, Pd / ZnO, CuO / Fe2O3 / ZrO2, CuO / La2O3 / ZrO2, CuO / ZnO / ZrO2 / Al2O3, and CuO / ZnO / La2O3 / Al2O3, preferably at least one of CuO / ZnO / Al2O3, Pd / ZnO, and CuO / Fe2O3 / ZrO2. In the CuO / ZnO / Al2O3 catalyst, the molar ratio of Cu, Zn, and Al can be 1:(0.1-2):(0.05-2.2), preferably 1:(0.2-1.25):(0.1-1.25). In the Pd / ZnO catalyst, the molar ratio of Pd to ZnO can be 1:(0.5-15), preferably 1:(2.5-8). In the CuO / Fe2O3 / ZrO2 catalyst, the molar ratio of Cu, Fe and Zr can be 1:(0.01-0.75):(0.1-5.6), preferably 1:(0.02-0.65):(0.8-2.3).

[0097] In the method of producing hydrogen by steam reforming, the volume ratio of alcohol to steam can be 1:(0.2-6.8), preferably 1:(0.5-3).

[0098] In the method for producing hydrogen by steam reforming, the conditions for the reforming reaction may include: a temperature of 125-725°C, preferably 175-475°C; and a space velocity of 1250-25500 h⁻¹ for the alcohol and steam (feed gas). -1 Preferably 3750-15000h -1 The conditions for the reforming reaction may further include: a pressure of 0.01-1.25 MPa, preferably 0.05-0.75 MPa.

[0099] In the method for producing hydrogen by steam reforming, the method further includes introducing the gas that has not permeated through the first composite membrane into a second reactor equipped with a second composite membrane for carbon dioxide capture (physical recovery) or conversion (chemical).

[0100] The inventors of this invention discovered a correlation between the hydrogen permeation diffusion rate and the lattice parameters of the palladium membrane. By determining the lattice parameters of the palladium membrane based on the required hydrogen permeation diffusion rate, and then selecting the preparation process or raw materials based on the lattice parameters, the preparation process and raw materials are simplified, making the preparation and application of the palladium membrane more targeted. Therefore, according to one embodiment of this invention, the method for producing hydrogen through steam reforming may further include determining the hydrogen permeation diffusion rate J required for carbon dioxide capture or conversion. H2 (Generally 0.2-0.4 mol·m) -2 ·s -1 The process involves determining the lattice parameter k of the palladium film; providing a second composite film (particularly an Au-free palladium film) comprising the palladium film having the stated lattice parameter; and performing carbon dioxide capture or conversion in the presence of the provided second composite film. Preferably, the hydrogen permeation diffusion rate J... H2 The relationship with the lattice parameter k satisfies Equation II (for more details, please refer to the specification of the applicant's invention patent application "Method for Carrying Hydrogen-Related Reactions" filed on the same day, the entire contents of which are incorporated herein by reference):

[0101]

[0102] In Equation II, J H2 The unit is mol·m -2 ·s -1 ;

[0103] The unit of k is nm;

[0104] n is the number of metal types contained in the palladium film;

[0105] M a Let be the average relative atomic mass of n alloys, expressed in g / mol.

[0106] M i is the relative atomic mass of the i-th metal, in g / mol;

[0107] ρ a The average density of n alloys is expressed in kg / m³. 3 ;

[0108] ρ i Let be the density of the i-th metal, in kg / m³. 3 ;

[0109] d represents the thickness of the palladium film, in meters (m).

[0110] b is the correction factor, and its value ranges from 0.5 to 3.

[0111] Preferably, when the palladium film is made of PdCu alloy, the value of b ranges from 0.54 to 1.25.

[0112] Preferably, when the palladium film is made of PdAg alloy, the value of b ranges from 0.61 to 1.68.

[0113] Preferably, when the palladium film is made of PdAu alloy, the value of b ranges from 0.7 to 3.

[0114] Preferably, when the palladium film is made of PdCuAg alloy, the value of b ranges from 0.59 to 1.62.

[0115] Preferably, when the palladium film is made of PdCuAu alloy, the value of b ranges from 0.75 to 2.65.

[0116] Preferably, when the palladium film is made of PdCuNi alloy, the value of b ranges from 0.51 to 1.22.

[0117] According to a preferred embodiment of the present invention, the second composite membrane comprises a palladium membrane and a silica-alumina molecular sieve loaded with sodium-modified nano-Fe3O4 attached to the surface of the palladium membrane (i.e., sodium-modified nano-Fe3O4 loaded on the silica-alumina molecular sieve). The thickness of the palladium membrane can be 0.5-30 μm, preferably 5-15 μm. The palladium membrane can be made of metallic palladium or a palladium alloy, preferably a composite palladium-based alloy material as described above or a composite palladium-based alloy material E as described below: the composite palladium-based alloy material E contains Pd, Cu, and Ag, and the molar ratio of Pd, Cu, and Ag is 100:(12-38):(9-25), and the crystal structure of the composite palladium-based alloy material E is face-centered cubic close-packed with a lattice parameter k of 0.4025-4255 nm.

[0118] According to the present invention, preferably, the half-width at half-maximum (WHM) of at least one characteristic peak of 2θ in the range of 10°-90° in the XRD pattern of the composite palladium-based alloy material E is less than or equal to 0.1745 or 0.1633; more preferably, the WHM of all characteristic peaks of 2θ in the range of 10°-90° in the XRD pattern of the composite palladium-based alloy material E is less than or equal to 0.1745 or 0.1633, more preferably less than or equal to 0.1047 or less than or equal to 0.087 or less than or equal to 0.084 or less than or equal to 0.078 or less than or equal to 0.072 or less than or equal to 0.069 or less than or equal to 0.064 or less than or equal to 0.055 or less than or equal to 0.039, and typically greater than or equal to 0.052 or greater than or equal to 0.059. Or greater than or equal to 0.062 or greater than or equal to 0.068 or greater than or equal to 0.073; More preferably, in the XRD pattern of the composite palladium-based alloy material E, the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 40° ± 1° (i.e., the characteristic peak of crystal plane (110)) is less than or equal to 0.0698 or 0.055, or the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 46° ± 1° (i.e., the characteristic peak of crystal plane (111)) is less than or equal to 0.0873 or 0.069, or the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 69° ± 1° (i.e., the characteristic peak of crystal plane (220)) is less than or equal to 0.1047 or 0.072, or the half-width at half-maximum (WHM) of the characteristic peak at 2θ = 83° ± 1° (i.e., the characteristic peak of crystal plane (311)) is less than or equal to 0.1396. The full width at half maximum (FWHM) of the characteristic peak at 2θ = 87° ± 1° (i.e., the characteristic peak of the crystal plane (222)) is less than or equal to 0.1633 or 0.084.

[0119] Preferably, the second composite membrane is a tubular membrane.

[0120] Preferably, the second composite film may further include a support, wherein the palladium film (composite palladium-based alloy material E) is attached to the support, and the thickness of the support may be 0.1-20 mm, more preferably 2-5 mm.

[0121] Preferably, the silica-alumina molecular sieve in the second composite membrane is at least one of HZSM-5, HZSM-11, HZSM-12, HZSM-23, HZSM-34, HY, HMCM-22, HBEA, and HMOR.

[0122] Preferably, the thickness of the silica-alumina molecular sieve loaded with sodium-modified nano-Fe3O4 is 100-3750 nm, more preferably 350-1500 nm.

[0123] Preferably, the silicon-aluminum molar ratio of the silicon-aluminum molecular sieve in the second composite membrane is (2-50):1, more preferably (5-20):1; the average particle size is 50-420 nm, more preferably 150-300 nm; the average pore size is 0.25-225 nm, more preferably 0.75-35 nm; and the specific surface area is 25-600 m² / g. 2 / g, more preferably 50-500m 2 / g; crystallinity greater than or equal to 92%, more preferably 96-99%.

[0124] Preferably, the average particle size of the sodium-modified nano-Fe3O4 in the second composite film is 5-300 nm, and more preferably 10-100 nm.

[0125] Preferably, the loading of sodium-modified nano-Fe3O4 in the second composite film is such that the molar ratio of Pd to Fe is 1:(0.001-0.1), more preferably 1:(0.001-0.03).

[0126] Preferably, the molar ratio of Na to Fe in the sodium-modified nano Fe3O4 in the second composite film is 1:(1-10), more preferably 1:(3-6).

[0127] According to the present invention, the method for preparing the composite palladium-based alloy material E preferably includes: depositing Pd, Cu and Ag on a support, and then alloying the support on which Pd, Cu and Ag have been deposited, wherein the molar ratio of Pd, Cu and Ag is 100:(12-38):(9-25); wherein the alloying treatment is performed by: heat treatment in an activating atmosphere at a temperature of 500-650°C (e.g., 500°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C or any value between the above values) and a pressure greater than 0.1 MPa, and then cooling to below 200°C at a rate greater than 30°C / min (e.g., 31, 35, 40, 45, 55, 65, 70, 80, 100°C / min or any value between the above values). The gas providing the activating atmosphere may optionally include an alkaline gas, as described above, and will not be repeated here. More preferably, the alloying treatment is performed as follows: after treatment in an activating atmosphere at a temperature of 600-625°C and a pressure of 0.56-0.73 MPa for 1.5-7 hours, the temperature is then reduced to 150-200°C at a rate of 55-75°C / min.

[0128] The preparation method of the second composite membrane may include: (I) placing a palladium membrane or the alloyed material (composite palladium-based alloy material E) in a solution of a precursor containing a silicon-aluminum molecular sieve and sequentially performing hydrothermal crystallization, drying and calcination to obtain a composite membrane precursor;

[0129] (II) Loading (or depositing) sodium-modified nano-Fe3O4 on the surface of the composite membrane precursor.

[0130] In the preparation method of the second composite membrane, preferably, the precursor solution containing silicon-aluminum molecular sieve contains a silicon source, an aluminum source, a template agent, and water.

[0131] In the preparation method of the second composite membrane, preferably, the molar ratio of silicon source, aluminum source, template agent and water is 100:(2-50):(15-65):(60-2400), more preferably 100:(5-20):(20-50):(70-1250).

[0132] In the preparation method of the second composite membrane, preferably, the amount of the solution of the precursor containing silicon-aluminum molecular sieve is 0.025-0.85 ml relative to 1 g of palladium membrane or alloyed material.

[0133] In the preparation method of the second composite membrane, the silicon source can be a substance commonly used in the art that can provide silicon. Preferably, the silicon source is at least one of silicate esters, silicates, and silicon dioxide, more preferably selected from at least one of tetrabutyl orthosilicate, tetraethyl orthosilicate, sodium silicate, potassium silicate, silica sol, and water glass. Preferably, the aluminum source can be a substance commonly used in the art that can provide aluminum. Preferably, the aluminum source is at least one of aluminate, alumina, aluminum salt, aluminum sol, and aluminum alkoxide, more preferably selected from at least one of sodium aluminate, boehmite, aluminum sulfate, aluminum nitrate, and aluminum isopropoxide. Preferably, the template agent is at least one of tetraalkylammonium hydroxide, alkylamine, and tetraalkylammonium halide, more preferably selected from at least one of tetrabutylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium hydroxide, triethylamine, hexadecyltrimethylammonium bromide, and isopropylamine.

[0134] In the preparation method of the second composite membrane, preferably, the hydrothermal crystallization method involves aging followed by crystallization. More preferably, the aging conditions include an aging temperature of 70-90℃. More preferably, the aging conditions also include an aging time of 6-10 hours. More preferably, the crystallization conditions include a crystallization temperature of 160-190℃. More preferably, the crystallization conditions also include a crystallization time of 24-48 hours. Aging can be carried out under stirring conditions, preferably at a stirring rate of 800-1000 rpm. Crystallization can also be carried out under stirring conditions, preferably at a stirring rate of 15-30 rpm.

[0135] In the preparation method of the second composite membrane, there are no special requirements for the drying conditions. Preferably, the drying conditions include: drying temperature of 50-80℃ and drying time of 8-12h.

[0136] In the preparation method of the second composite membrane, preferably, the calcination conditions include: a calcination temperature of 575-625℃. Preferably, the calcination conditions also include: a calcination time of 4-6 hours.

[0137] In the preparation method of the second composite membrane, when the silicon source and / or aluminum source (such as sodium silicate, potassium silicate, water glass, sodium aluminate) contains Na or K, the calcined product is a sodium-type molecular sieve. Therefore, in order to obtain a hydrogen-type molecular sieve, the method preferably further includes ammonium exchange of the calcined product. Conventional methods can be used for ammonium exchange, which will not be elaborated here.

[0138] In the preparation method of the second composite membrane, preferably, the method of depositing sodium-modified nano-Fe3O4 on the surface of the composite membrane precursor is as follows: impregnating the composite membrane precursor with a solution containing an iron source and a sodium source, followed by drying and calcination, wherein the molar ratio of Na to Fe in the solution containing the iron source and the sodium source is 1:(1-10). More preferably, the concentration of Fe in the solution containing the iron source and the sodium source can be 0.01-0.86 mol / L. More preferably, the concentration of Na in the solution containing the iron source and the sodium source can be 0.01-0.55 mol / L. More preferably, the amount of solution containing the iron source and the sodium source used is 0.01-0.05 ml relative to 1 g of the composite membrane precursor. Preferably, the iron source can be a substance commonly used in the art that can provide iron. More preferably, the iron source is selected from at least one of ferric salts and ferrous salts, and even more preferably from at least one of FeCl3, FeCl2, Fe(NO3)3, FeSO4, NH4Fe(SO4)2, and (NH4)2Fe(SO4)2. According to a particularly preferred embodiment, the iron source is iron ions (Fe2+) in a molar ratio of 1.5-2.5. 3+ ) source (such as FeCl3) and ferrous ions (Fe 2+ Source (such as FeCl2).

[0139] More preferably, the sodium source can be a substance commonly used in the art that can provide sodium. Preferably, the sodium source is selected from at least one of sodium hydroxide and sodium salts, more preferably from at least one of NaOH, NaHCO3, Na2CO3, and NaCl. More preferably, the pH value of the solution containing the iron source and the sodium source can be 8-12, preferably 9-11. When using NaOH as the sodium source, the content of NaOH in the solution is preferably such that the pH value of the solution meets the above-mentioned range. More preferably, the impregnation conditions include: an impregnation temperature of 15-85℃, more preferably 25-60℃; and an impregnation time of 0.5-3.5h, more preferably 1-2h. More preferably, the calcination conditions include: a calcination temperature of 325-500℃ and a calcination time of 3-5h. More preferably, before impregnating the composite membrane precursor with a solution containing iron and sodium sources, the solution containing iron and sodium sources is aged under the following conditions: temperature of 20-70°C and time of 0.5-3h.

[0140] The present invention will be described in detail below through examples. In the following examples and comparative examples, the inner surface of the support is sealed with polytetrafluoroethylene (PTFE) material, so molecular sieves, nanoparticles, etc. are selectively loaded only on the outer surface of the support, and the PTFE material is peeled off before application or performance testing.

[0141] Examples A1-A4

[0142] (1) Using a porous stainless steel tube as the support (tubular, inner diameter: 10 mm, outer diameter: 13 mm; average pore size: 0.25 μm, porosity: 65%), the support was first soaked in anhydrous ethanol for 30 minutes to remove surface contaminants such as dust and grease. Then, the surface and inner side of the support were rinsed with deionized water and placed in warm water for vacuum cleaning to remove residual ethanol from the pores. Finally, it was placed in an oven and dried at 423 K for 4 hours. Pd and Au were deposited on the support using electroplating according to Faraday's law. The molar ratio M of Pd to Au is shown in Table 1. The effective film area was 25 cm². 2 The electroplating process involved using a conductive layer carrier as the working electrode, a platinum electrode (Pd plating) and a ruthenium / titanium oxide composite electrode (RuO2 / TiO2) (Au plating) as counter electrodes, and a saturated calomel electrode as the reference electrode. At a temperature of 30°C, the metal ions (Pd...) in the plating bath... 2+ Au 3+The concentration of the ammonium chloride was 0.01-0.05 mol / L. Electroplating experiments were conducted using cyclic voltammetry, with a working voltage range of -0.60V to -0.90V, a scan rate of 0.0075V / s, a scan period of 1000, and a sensitivity of 0.0001A / V. Simultaneously, during the electroplating process, a plunger-type constant flow pump was used to add the following solutions to the plating bath at rates of 1-2 ml / min: 0.05 mol / L ammonium palladium chloride ((NH4)2PdCl4) solution; 0.01 mol / L chloroauric acid (HAuCl4) solution; 0.1 ml / min: ethylenediamine (EDA, 99%, analytical grade); 0.05 ml / min: disodium ethylenediaminetetraacetate (EDTA-2Na, 99%, analytical grade); and 0.01 ml / min: bipyridine (C...). 10 H8N2 (99%, analytical grade). The plating bath was vigorously stirred (1000 r / min) while the above solution was added. Every 30 min of electroplating, the working electrode, cleaned with distilled water, was immersed for 10 min in 0.05 mol / L phosphoric acid (H3PO4) solution and 0.05 mol / L dipotassium hydrogen phosphate (K2HPO4) solution, respectively. After the cyclic voltammetry procedure, the working electrode was treated in distilled water at 95℃ for 15 min before being removed. The Pd and Au deposited support was subjected to high-temperature alloying treatment. The alloying treatment method was as follows: after treatment in an activating atmosphere at temperature T1 and pressure P for a period of time (t); the temperature was then reduced to T2 at a cooling rate V. The activating atmosphere consisted of H2 and N2, with the volume ratio of H2 to N2 = R1. The amount of activating atmosphere gas provided was such that the alloying pressure was P. Detailed parameters are shown in Table 1.

[0143] (2) The alloyed material obtained in step (1) was placed in the precursor solution of ZSM-5 molecular sieve for hydrothermal crystallization (aging and crystallization were performed in sequence), drying and calcination. The molar ratio R2 of silicon source, aluminum source, template agent and water and the conditions of each step are shown in Table 1 to obtain the composite membrane precursor. In the precursor solution of ZSM-5 molecular sieve, tetrapropylammonium hydroxide (TPAOH) is the template agent, tetrabutyl orthosilicate (TEOS) is the silicon source and sodium aluminate is the aluminum source. The amount of silicon-aluminum molecular sieve precursor solution used is 0.5 ml relative to 1 g of alloyed material.

[0144] (3) The surface of the composite membrane precursor was silanized using a silanizing agent (Table 1) to obtain the composite membrane. The silanization process was as follows: the composite membrane was silanized with the silanizing agent for 45 min in a chemical vapor deposition furnace under certain temperature, pressure, vacuum and inert purge gas conditions. The silanization conditions were: temperature of 55℃, system pressure of 25 kPa (atmospheric pressure of 101.325 kPa) maintained by a vacuum pump; inert purge gas was N2 with a flow rate of 35-75 ml / min; the silanizing agent was an analytical grade sample, and 5 ml of the sample was measured relative to 1 g of composite membrane precursor and placed in a quartz boat, with the quartz boat located on both sides of the sample.

[0145] Example A5

[0146] The procedure was carried out in accordance with Example A1, except that the molar ratio of Pd to Au was changed to 1:1.

[0147] Example A6

[0148] The procedure was carried out in accordance with Example A1, except that the molar ratio of Pd to Au was changed to 1:0.2.

[0149] Example A7

[0150] The process was carried out in accordance with Example A1, except that the gas providing the activation atmosphere was changed to hydrogen and ammonia, with a volume ratio of 2.5:1, and the treatment time in the activation atmosphere was t = 3 hours.

[0151] Example A8

[0152] The process was carried out in accordance with Example A2, except that the gas providing the activation atmosphere was changed to hydrogen and hydrazine, with a volume ratio of 3:1, and the treatment time in the activation atmosphere was t = 2.5 h.

[0153] Example A9

[0154] The process was carried out in accordance with Example A3, except that the gas providing the activation atmosphere was changed to hydrogen and phosphine, and the volume ratio of the two was 3.5:1, and the treatment time in the activation atmosphere was t = 2h.

[0155] Example AD1

[0156] The process is carried out in accordance with Example A1, except that the gas providing the activating atmosphere is only N2.

[0157] Example AD2

[0158] The process is carried out in accordance with Example A1, except that the gas providing the activating atmosphere is only H2.

[0159] Example AD3

[0160] The process is carried out in accordance with Example A1, except that the gas providing the activating atmosphere is only argon.

[0161] Example AD4

[0162] The process was carried out in accordance with Example A1, except that the gases providing the activation atmosphere were hydrogen and CO2 (volume ratio 1:1).

[0163] Example A10

[0164] The process was carried out according to Example A7, except that the product obtained in step (3) was further subjected to a molybdenum oxide deposition step. Specifically, the silanized material was placed in a high-pressure hydrothermal synthesis vessel with PTFE (polytetrafluoroethylene) as the liner, and a mixture of (NH4)6Mo7O2·4H2O, (NH4)2CO3, N2H4·H2O, and LiOH was added, wherein the molar ratio of the above substances was 1:2:5:3, and the molar concentration of (NH4)6Mo7O2·4H2O was 0.075 mol / L. The mixture was hydrothermally synthesized at 200°C in a rotary oven for 36 h, resulting in a uniform MoO2 nanoparticle layer on the material surface. The scanning electron microscope image of the obtained molybdenum oxide nanoparticles is shown below. Figure 7 .

[0165] Example A11

[0166] The process was carried out in accordance with Example A7, except that the product obtained in step (3) was further subjected to a step of depositing molybdenum oxide. Specifically, the silanized material was placed in a high-pressure hydrothermal synthesis vessel with PTFE (polytetrafluoroethylene) material as the liner, and a mixture of (NH4)6Mo7O2·4H2O, (NH4)2CO3, N2H4·H2O, and LiOH was added, wherein the molar ratio of the above substances was 1:3:7.5:4.5, and the molar concentration of (NH4)6Mo7O2·4H2O was 0.05mol / L. The mixture was hydrothermally synthesized for 36 hours at 200°C in a rotary oven, and a uniform MoO2 nanoparticle layer was obtained on the surface of the material.

[0167] Example A12

[0168] The process was carried out according to Example A7, except that the product obtained in step (3) was further subjected to a step of depositing tungsten oxide. Specifically, the silanized material was placed in a high-pressure hydrothermal synthesis vessel with PTFE (polytetrafluoroethylene) as the liner, and a mixture of Na2WO4·2H2O, H2O, and HCl was added, wherein the molar ratio of the above substances was 1:50:20, and the concentration of Na2WO4·2H2O was 0.03 mol / L. The mixture was vigorously stirred to form a uniform suspension, and hydrothermally synthesized at 180°C in a rotary oven for 24 hours. A uniform WO3 nanoparticle layer was obtained on the surface of the material.

[0169] Example AD5

[0170] The procedure was carried out in accordance with Example A1, except that the temperature was reduced to T2 at a rate of V = 5°C / min.

[0171] Example AD6

[0172] The process was carried out in accordance with Example A1, except that the alloying temperature T1 = 700°C.

[0173] Example AD7

[0174] The alloying process was carried out in accordance with Example A1, except that the alloying pressure P = 0.1 MPa.

[0175] Table 1

[0176]

[0177] Examples E1-E4

[0178] (1) Using a porous stainless steel tube as the support (tubular, inner diameter: 10 mm, outer diameter: 13 mm; average pore size: 0.25 μm, porosity: 65%), the support was first soaked in anhydrous ethanol for 30 minutes to remove surface contaminants such as dust and grease. Then, the surface and inner side of the support were rinsed with deionized water and placed in warm water for vacuum cleaning to remove residual ethanol from the pores. Finally, it was placed in an oven and dried at 423 K for 4 hours. According to Faraday's law, Pd, Cu, and Ag atomic molar ratios M were deposited on the support using electroplating, as shown in Table 2. The effective film area was 50 cm². 2 The electroplating process involved using a conductive layer carrier as the working electrode, a platinum electrode (Pd plating), a waveguide with 99.999% copper content (Cu plating), and a silver electrode (Ag plating) as the counter electrodes, with a saturated calomel electrode as the reference electrode. The plating solution contained metal ions (Pd...) 2+ Cu 2+ Ag +The concentration was 0.01-0.1 mol / L. Electroplating experiments were carried out using cyclic voltammetry, with the working voltage range being -0.60V to -0.90V, the scan rate being 0.0075V / s, the scan period being 1000, and the sensitivity being set to 0.0001A / V. Meanwhile, during the electroplating process, a plunger-type constant flow pump was used to add the following solutions to the plating bath at a rate of 1-2 ml / min: 0.05 mol / L ammonium palladium chloride ((NH4)2PdCl4) solution; 0.5-1.5 ml / min: 0.075 mol / L copper nitrate (Cu(NO3)2) solution; 0.25-1 ml / min: 0.05 mol / L silver nitrate (AgNO3) solution; 0.1 ml / min: ethylenediamine (EDA, 99%, analytical grade); 0.05 ml / min: disodium ethylenediaminetetraacetate (EDTA-2Na, 99%, analytical grade); and 0.01 ml / min: bipyridine (C... 10 H8N2 (99%, analytical grade). The plating bath was vigorously stirred (1000 r / min) while the above solution was added. Every 30 min of electroplating, the working electrode, cleaned with distilled water, was immersed for 10 min in 0.05 mol / L phosphoric acid (H3PO4) solution and 0.05 mol / L dipotassium hydrogen phosphate (K2HPO4) solution, respectively. After the cyclic voltammetry procedure, the working electrode was treated in distilled water at 95℃ for 15 min before being removed. The Pd, Cu, and Ag deposited support was subjected to high-temperature alloying treatment. The alloying treatment was performed as follows: under an activating atmosphere, at temperature T1 and pressure P, for a period of time (t); then, the temperature was reduced to T2 at a cooling rate V. The activating atmosphere consisted of H2 and N2, with the volume ratio of H2 to N2 equal to R1. The amount of activating atmosphere gas provided ensured that the alloying pressure was P. Detailed parameters are shown in Table 2.

[0179] (2) The alloyed material obtained in step (1) was placed in the precursor solution of HZSM-5 molecular sieve for hydrothermal crystallization (aging and crystallization were performed in sequence), drying, calcination and ammonium exchange with ammonium nitrate (NH4NO3). The molar ratio R2 of silicon source, aluminum source, template agent and water and the conditions of each step are shown in Table 2 to obtain the composite membrane precursor. In the precursor solution of HZSM-5 molecular sieve, tetrapropylammonium hydroxide is used as template agent, tetrabutyl orthosilicate (TEOS) is used as silicon source and sodium aluminate is used as aluminum source. The amount of silicon-aluminum molecular sieve precursor solution used is 0.25 ml relative to 1 g of alloyed material.

[0180] The specific method of ammonium exchange is as follows: a 0.5 mol / L ammonium nitrate solution (NH4NO3) is used as the ion exchanger, according to Na... +Add 1.5 times the feed amount, immerse the calcined product to be exchanged into the above ion exchanger, and stir at 50 r / min for 2 h at 80 °C and normal pressure; dry the ion-exchanged sample in an oven at 100 °C for 6 h. Repeat the above operation once by immersing the dried sample into the above ion exchanger.

[0181] (3) Sodium-modified nano-Fe3O4 was deposited on the surface of the composite membrane precursor to obtain a composite membrane. The steps for depositing sodium-modified nano-Fe3O4 were as follows: a mixed solution of FeCl3 and FeCl2 was prepared using FeCl3·6H2O and FeCl2·4H2O in a molar ratio of 2. The pH was adjusted with 0.1 mol / L NaOH to obtain a solution containing iron and sodium sources. The mixture was stirred at a stirring rate of 500 r / min and aged to obtain an impregnation solution. The composite membrane precursor was then impregnated in the impregnation solution and dried at 25 °C and 0.002 MPa vacuum for 10 h to remove free water. Subsequently, it was calcined at 475 °C for 5 h to remove water of crystallization and template agent. The molar ratio R3 of Na to Fe in the solution containing iron and sodium sources (as shown in Table 2) was 0.025 ml relative to 1 g of composite membrane precursor.

[0182] Table 2

[0183]

[0184]

[0185] Example E5

[0186] The process was carried out in accordance with Example E1, except that the gas providing the activation atmosphere was changed to hydrogen and ammonia, with a volume ratio of 2.5:1, and the treatment time in the activation atmosphere was t = 4h.

[0187] Example E6

[0188] The process was carried out in accordance with Example E1, except that the gas providing the activation atmosphere was changed to hydrogen and hydrazine, with a volume ratio of 3:1, and the treatment time in the activation atmosphere was t = 3.5 h.

[0189] Example E7

[0190] The process was carried out in accordance with Example E1, except that the gas providing the activation atmosphere was changed to hydrogen and phosphine, with a volume ratio of 3.5:1, and the treatment time in the activation atmosphere was t = 1.5 h.

[0191] Example ED1

[0192] The process is carried out in accordance with Example E1, except that the gas providing the activating atmosphere is only N2.

[0193] Example ED2

[0194] The process is carried out in accordance with Example E1, except that the gas providing the activating atmosphere is only H2.

[0195] Example ED3

[0196] The process is carried out in accordance with Example E1, except that the gas providing the activation atmosphere is only argon.

[0197] Example ED4

[0198] The process is carried out in accordance with Example E1, except that the gases providing the activation atmosphere are hydrogen and CO2 (volume ratio 1:1).

[0199] Example ED5

[0200] The process was carried out in accordance with Example E1, except that the temperature was reduced to T2 at a rate of V = 5°C / min.

[0201] Example ED6

[0202] The process was carried out in accordance with Example E1, except that the alloying temperature T1 = 700°C.

[0203] Example ED7

[0204] The process was carried out in accordance with Example E1, except that the alloying pressure P = 0.1 MPa.

[0205] Example ED8

[0206] The procedure was carried out in accordance with Example E1, except that the molar ratio of Pd, Cu and Ag atoms was M = 100:500:500.

[0207] Example ED9

[0208] The procedure was carried out in accordance with Example E1, except that the molar ratio of Pd, Cu, and Ag atoms was M = 100:0.5:0.5.

[0209] Example E8

[0210] The process was carried out in accordance with Example A7, except that Pd and Cu were deposited on the support in a weight ratio of 1:1.3.

[0211] Example E9

[0212] The process was carried out in accordance with Example A7, except that Pd, Cu and Ni were deposited on the support in a weight ratio of 1:1:0.6.

[0213] Test case

[0214] (I) The materials obtained after alloying treatment in step (1) of each embodiment and comparative example (i.e., composite palladium-based alloy materials) were characterized. The characterization method is as follows, and the crystal structure parameters of the composite palladium-based alloy materials are shown in Table 3-7.

[0215] The crystal structure analysis of the composite palladium-based alloy was performed on an X'Pert PRO / PANalytical automated X-ray diffractometer manufactured by Philips, Netherlands. The experimental conditions were Cu K α X-rays (λ = 0.1543 nm), tube voltage 40 kV, current 40 mA, diffraction angle 2θ scan range 10-90°. The interplanar spacing of the sample was calculated using the Bragg equation.

[0216] d=λ / 2sinθ

[0217] Where λ corresponds to Cu K α The wavelength of the radiation, θ is the angle of the diffraction peak.

[0218] The crystal structure of the composite palladium-based alloy was tested at the European Synchrotron Radiation Facility (beam BM25A) in France, which has higher resolution, with synchrotron radiation λ = 0.0618886 nm or 0.077449 ​​nm and tube voltage of 10.0335 keV or 20.0335 keV. Initially, a 10 × 1 mm sample was used. 2 The sample was placed in a 2mm diameter quartz capillary tube, with both ends sealed with quartz wool. The capillary tube was then mounted on a rotating sample stage (to ensure uniform temperature and a larger X-ray irradiation area). The test temperature range was 298-473K (heated by a hot air blower), and the pressure range was 10... -4 The test atmosphere was -130 kPa. Hydrogen gas was first introduced and treated for 30 minutes, then a vacuum was drawn, and helium gas was introduced as a protective gas for measurement.

[0219] Methods for testing the lattice parameters of composite palladium-based alloy materials: Combining the above-mentioned in-situ XRD tests, the cell parameters of the palladium-based alloy materials are obtained (represented by three cell constants a, b, and c, and the three inter-edge angles α, β, and γ). According to the formula d1 = a / (α... 2 +β 2 +γ 2 ) 0.5 d2=b / (α) 2 +β 2 +γ 2 ) 0.5 d3=c / (α) 2 +β 2 +γ 2 ) 0.5The interplanar spacing (d1 d2 d3) of the corresponding characteristic crystal planes is calculated. For example, the PdAu alloy material obtained in this invention belongs to the face-centered cubic close-packed (FCC) structure, and its characteristic crystal planes include (110), (111), (220), (311), and (222). At the same time, according to the X-ray diffraction results, a series of different characteristic crystal plane ratios (the intensity corresponding to different crystal planes) can be obtained. For example, in the PdAu alloy material obtained in this invention, the (110) plane corresponds to the characteristic peak at 2θ = 40° ± 1°, the (111) plane corresponds to the characteristic peak at 2θ = 46° ± 1°, the (220) plane corresponds to the characteristic peak at 2θ = 69° ± 1°, the (311) plane corresponds to the characteristic peak at 2θ = 83° ± 1°, and the (222) plane corresponds to the characteristic peak at 2θ = 87° ± 1°. Using HighScorePlus analysis software, and combining the peak intensities of the aforementioned characteristic crystal planes, the lattice parameters k of the corresponding materials are calculated.

[0220] The thickness of the composite palladium-based alloy material was tested by scanning electron microscopy (model: JSM-7610F). The thickness of the alloy film was determined by measuring the corresponding scale according to the magnification. The surface smoothness of the obtained composite palladium-based alloy material could also be observed by scanning electron microscopy. The results showed that the surface of the composite palladium-based alloy material prepared by this invention was smooth and free of defects.

[0221] The method for testing the full width at half maximum (FWHM) of the composite palladium-based alloy material is as follows: based on the XRD spectrum test results, combined with HighScore Plus software analysis, the FWHM radian value is obtained. The XRD spectra of the composite palladium-based alloy materials obtained in Examples A1 and E8 are shown below. Figure 2a and Figure 2b As shown.

[0222] (II) Solid-phase stripping treatment was performed on the composite films (materials obtained before oxide deposition) obtained from each embodiment and comparative example to remove the molecular sieve for characterization. The characterization method is as follows, and the relevant structural parameters of the molecular sieve attached to the surface of the composite palladium-based alloy material are obtained, as shown in Tables 3 and 5.

[0223] The molecular sieve was analyzed using an Empyrean X-ray diffractometer from Malvern-Panalytical. The testing conditions were: Cu target, Ka radiation, Ni filter, tube voltage 40 kV, tube current 40 mA, scintillation counter, step size 0.0131°, scan range 5–35°, and scan rate 2.5° / min. The results showed that it is a ZSM-5 silica-alumina molecular sieve with a double ten-membered ring cross-channel structure (MFI structure). Figure 2cThe XRD pattern of the molecular sieve obtained in Example A1 is shown. The four characteristic peaks between 23° and 25° indicate that the material contains a double ten-membered ring cross-channel structure, which is consistent with the characteristics of ZSM-5 silica-alumina molecular sieve. The XRD patterns of the molecular sieves in each example are consistent with... Figure 2c Similarly, this indicates that the obtained molecular sieves are all ZSM-5 silica-alumina molecular sieves;

[0224] Methods for determining the specific surface area and average pore size of molecular sieves: The tests were conducted using a Micromeritics ASAP 2020 physical adsorption analyzer (USA). Samples were subjected to high vacuum treatment at 363 K and 573 K for 1 h and 3 h, respectively, followed by adsorption using N2 as the adsorbate at a constant temperature of 77 K. The BET specific surface area was obtained from the N2 adsorption isotherm combined with the BET equation; the average pore size was determined using the BJH method, calculated from the desorption branch of the N2 adsorption isotherm.

[0225] Method for testing the crystallinity of molecular sieves: A conventional X-ray diffractometer was used with a tube voltage of 40 kV, a tube current of 40 mA, and a scanning speed of 2.5° / min. The diffraction patterns of the samples were recorded within the range of 2θ = 5-35°. ZSM-5 sample M196697 from Shanghai Aladdin Biochemical Technology Co., Ltd. was used as a reference sample, with its relative crystallinity set to 100. The relative crystallinity of each sample was calculated by summing the peak intensities of its characteristic diffraction peaks at 2θ = 7.96°, 8.83°, 23.18°, 23.99°, and 24.45° and comparing this sum with the sum of the peak intensities of the reference sample.

[0226] The methods for testing the average particle size of molecular sieves are as follows: observe the microstructure of the molecular sieve in the sample using a transmission electron microscope and measure the diameter according to the scale bar; calculate the corresponding particle size distribution by taking the average of several samples using mathematical statistical methods.

[0227] The thickness of the molecular sieve is determined by scanning electron microscopy, and the thickness of the molecular sieve membrane is determined by measuring the corresponding scale according to the magnification.

[0228] The method for determining the infrared hydroxyl content of molecular sieves is as follows: Using KBr as a background, the Fourier transform infrared spectrum of the sample is recorded on a Bruker-INVENIO R and Tensor 27 infrared spectrometer. The sample is placed in a flow cell and vacuumed at 823 K for 2 hours, with the wavelength ranging from 4000 to 650 cm⁻¹. -1 The hydroxyl content within a certain range was determined by summing 32 scans at a specific wavenumber. The corresponding spectrum was obtained at a wavenumber of 3500 cm⁻¹. -1 The nearby peaks represent the relative content of hydroxyl groups in the molecular sieve, wavenumber 3750 cm⁻¹. -1The peaks near the molecular sieve represent the relative content of hydroxyl groups at the molecular sieve tip. The degree of reduction in the total amount of hydroxyl groups before and after hydrophobic treatment can be determined based on the change in peak area. Specifically, a larger peak area at the corresponding position indicates a higher hydroxyl content, which can qualitatively describe the hydrophobic properties of the membrane material (e.g., the infrared characterization results of hydroxyl groups before and after silanization reagent treatment in Example A1 are shown in Figure 1). Figure 5 (The dashed line represents the area before hydrophobic treatment, and the solid line represents the area after hydrophobic treatment.) As shown, the wavenumber after hydrophobic treatment is 3500 cm⁻¹. -1 Wavenumber 3750cm -1 The significantly reduced peak area indicates that the hydrophobic treatment method described in this invention can effectively reduce the number of hydroxyl groups on the membrane material surface and improve the hydrophobicity of the membrane material. The infrared characterization results of hydroxyl groups before and after silanization reagent treatment in each embodiment are compared with... Figure 5 similar.

[0229] The silicon NMR test method for molecular sieves was as follows: On a VARIAN VNMRS 400WB NMR spectrometer, a single-pulse method was used with (CH3)3Si(CH2)3SO3Na as the chemical shift reference, and a rotation rate of 3 kHz and a cycle delay of 60 s were applied at a frequency of 79.43 MHz. 29 Si MAS NMR spectroscopy measurements were performed. Peaks with chemical shifts near -113 ppm and -103 ppm in the corresponding spectra represent the relative contents of the silicon framework structures Q4:Si(OSi)4 and Q3:Si(OSi)3OH in the molecular sieve, respectively. The ratio Q4 / Q3 represents the relative content of silanol groups on the molecular sieve. A higher Q4 / Q3 value indicates fewer silanol groups and better hydrophobicity of the material; see Table 3 for the corresponding values ​​of "Silanol Groups (Q4 / Q3)". The degree of reduction in the relative content of silanol groups can be determined based on the change in the ratio before and after hydrophobicity treatment (NMR characterization results before and after silanization reagent treatment in Example A1 are shown in the table). Figure 6 (The dashed line represents the area before hydrophobic treatment, and the solid line represents the area after hydrophobic treatment.) As shown, Q4 / Q3 increases after hydrophobic treatment, indicating that the hydrophobic treatment method described in this invention can effectively reduce the number of silanol groups on the surface of the membrane material and improve the hydrophobicity of the membrane material.

[0230] (III) Overall testing of composite membranes

[0231] The obtained composite membrane was subjected to liquid contact angle testing. Specifically, using a Data Physics Contact Angle System OCA 25 instrument with different liquids as the medium, the contact state between the composite membrane and the different liquids was captured by the instrument's built-in high-speed camera. The contact angle information was then obtained after processing by the built-in software. Figure 3 and Figure 4These are, respectively, experimental diagrams of the contact angles between the composite membrane before hydrophobic treatment and different liquids in Example A1, and experimental diagrams of the contact angles between the composite membrane after hydrophobic treatment and different liquids.

[0232] E act (Hydrogen permeation activation energy, unit: kJ·mol) -1 The test method involves measuring the hydrogen permeation rate from 573 K to 773 K under a transmembrane pressure difference of 0.1 MPa, combined with the Arrhenius equation J. H2 =J H2 ° exp(-E act / RT), calculated through measurement, where J H2 It is the hydrogen permeation diffusion rate, J H2 ° is the hydrogen permeation diffusion coefficient, R is the gas constant, and T is the absolute temperature. The higher the hydrogen permeation activation energy, the higher the hydrogen mass transfer resistance of the composite membrane material, and the more difficult it is for hydrogen to permeate and diffuse through the composite membrane.

[0233] J H2 (Hydrogen permeation rate, unit: mol·m) -2 ·s -1 The test method involves measuring the volume of hydrogen passing through the palladium-based composite membrane per minute (in liters) at 20℃ and a transmembrane pressure difference of 0.1 MPa, and then normalizing it to the hydrogen permeation rate (mol·m²) based on the membrane area (square meters). -2 ·s -1 ).

[0234] J N2 (Nitrogen permeation diffusion rate, unit: mmol·m) -2 ·s -1 The test method involves measuring the volume (mL) of nitrogen gas passing through the palladium-based composite membrane per minute at 20℃ and a transmembrane pressure difference of 0.1 MPa, and then normalizing it to the hydrogen permeation rate (mmol·m²) based on the membrane area (m²). -2 ·s -1 ).

[0235] The elemental composition of the composite film was analyzed by X-ray fluorescence (XRF) combined with inductively coupled plasma optical emission spectroscopy (ICP-OES), and the valence states of the elements were determined by X-ray photoelectron spectroscopy (XPS).

[0236] The morphology of the oxide nanoparticles was observed using a scanning electron microscope (SEM), and the average particle size was calculated.

[0237] The test results are shown in Table 3-7.

[0238] Table 3

[0239]

[0240] Table 4

[0241]

[0242]

[0243] Table 5

[0244]

[0245] Table 6

[0246]

[0247] Table 7

[0248]

[0249] (IV) Application Testing

[0250] The performance of the composite membranes prepared in the above embodiments and comparative examples in hydrogen production by reforming was tested.

[0251] (a) The Pd and Au-containing composite membrane (tubular membrane) prepared above and the CuO / ZnO / Al2O3 (Cu, Zn, and Al molar ratio of 1:1:0.23) steam reforming catalyst were co-encapsulated into a membrane reactor. The steam reforming catalyst was filled inside the tubular membrane at a volume of 5 ml. See [link to relevant documentation]. Figure 8 After being sealed with a stainless steel head with a graphite gasket 5, it is filled into a cylindrical stainless steel reactor 6 with a length of 500 mm and an inner diameter of 45 mm (see details). Figure 8 At 320℃, 0.35MPa, and a gas hourly space velocity of 10000h⁻¹, the following conditions were met: -1 Under certain conditions, a feed gas of CH3OH:H2O = 1:4 (molar ratio) was introduced for reforming to produce hydrogen. The detection of products and tail gases was as follows: Permeate (permeate) was analyzed online using a Shanghai Tianmei SCION-456 gas chromatograph equipped with FID and PDHID detectors to monitor product distribution and hydrogen purity changes in real time; Retentate (retentate) was analyzed online using a Shanghai Tianmei SCION-456 gas chromatograph equipped with TCD and FID detectors. Based on the detection results, methanol conversion rate, hydrogen selectivity, and hydrogen recovery rate were calculated. Products were tested every 5 hours. The continuous operating time was defined as the time during which the methanol conversion rate decreased to 90% of the initial value. The initial reaction values ​​and experimental measurements after reaching the continuous operating time are shown in Table 8. The amount of hydrogen produced is the sum of the amounts of hydrogen produced on the retentate and permeate sides. The formulas for calculating methanol conversion rate, hydrogen selectivity, and hydrogen recovery rate are as follows:

[0252] Methanol conversion rate (C) CH3OH = (Amount of carbon dioxide + Amount of carbon monoxide) / Amount of methanol introduced into the reactor

[0253] Hydrogen selectivity (S) H2 = Amount of hydrogen produced in the reaction / (Amount of hydrogen produced in the reaction + Amount of carbon monoxide produced in the reaction)

[0254] Hydrogen recovery rate (R) H2 = Amount of hydrogen permeated through the osmotic side / Amount of hydrogen produced in the reaction

[0255] Hydrogen-nitrogen selectivity (α(H2 / N2)) refers to the ratio between the hydrogen permeation / diffusion rate and the nitrogen permeation / diffusion rate at the defect site on the palladium film. A higher value indicates higher mechanical structural stability of the palladium film and fewer defects in the composite film material. Specifically, this is determined by measuring the hydrogen permeation / diffusion rate (J / N2) of the palladium film. H2 The nitrogen permeation diffusion rate at the defect under the same conditions (573 K, 0.5 MPa transmembrane pressure difference) (J) N2 According to the formula α(H2 / N2)=J H2 / J N2 The above measurement methods were used to obtain the result.

[0256] The carbon deposition content is tested by thermogravimetric analysis. The sample is heated from room temperature to 800°C at a rate of 5°C per minute in an air atmosphere. The carbon deposition content is obtained based on the change in mass of the sample before and after the reaction.

[0257] Table 8

[0258]

[0259] (b) Hydrogen production was carried out by steam reforming in the same manner as in step (a), except that 50 ppm of hydrogen sulfide (H2S) was added to the feed gas. The results are shown in Table 9.

[0260] Table 9

[0261]

[0262]

[0263] (c) The permeate tail gas (CO2 and H2 in a volume ratio of 1:4) obtained using composite membrane A1 in step (a) is introduced into another reactor. Under the catalytic action of Na-Fe3O4 / HZSM-5 in another composite membrane (containing Pd, Cu and Ag), gasoline distillate hydrocarbons and some unreacted CO2 are obtained. The specific operation is as follows:

[0264] The permeate tail gas (a mixture of CO2 and H2 with a volume ratio of 1:4 and a mixed gas volume hourly space velocity of 5000 h⁻¹) obtained using the composite membrane A1 in step (a) was introduced at 350°C and 0.3 MPa pressure. -1 The mixed gas was separated by another composite membrane, yielding pure hydrogen on the permeate side and a mixture of hydrogen and carbon dioxide on the residual side. Under the catalytic action of Na-Fe3O4 / HZSM-5 in the composite membrane, gasoline distillate hydrocarbons and some unreacted CO2 were obtained. The hydrogen product on the permeate side was analyzed online using a Shanghai Tianmei SCION-456 gas chromatograph equipped with FID and PDHID detectors to monitor hydrogen purity changes in real time. The components and relative contents of gasoline distillate hydrocarbons were detected using an Agilent 7890B chromatograph equipped with TCD and FID detectors, and the percentage contents of unreacted hydrogen, carbon dioxide, and other raw materials were also detected. Based on the detection results, the carbon dioxide conversion rate, gasoline distillate hydrocarbon selectivity, and hydrogen recovery rate were calculated. The products were tested every 5 hours. The continuous operating time was recorded when the carbon dioxide conversion rate decreased to 90% of the initial value. The initial reaction values ​​and experimental measurements after reaching the continuous operating time are shown in Table 10. The gasoline fraction hydrocarbons in the mixed components are enriched and absorbed by light naphtha absorbent. When the remaining CO2 concentration after the permeate side reaction is high enough, the carbon dioxide component is further enriched and sealed after compression.

[0265] Carbon dioxide conversion rate (C CO2 = Amount of carbon dioxide at reactor outlet / (Amount of carbon dioxide at reactor inlet - Amount of carbon dioxide at reactor outlet)

[0266] Gasoline fraction hydrocarbon selectivity (S gasline = Reactor outlet C5~C 12 The sum of the amounts of hydrocarbons / the total amount of hydrocarbons at the reactor outlet

[0267] Hydrogen recovery rate (R) H2 = Amount of hydrogen permeating through the osmotic side / Amount of hydrogen introduced into the reaction

[0268] Hydrogen-nitrogen selectivity (α(H2 / N2)) refers to the ratio between the hydrogen permeation / diffusion rate and the nitrogen permeation / diffusion rate at the defect site on the palladium film. A higher value indicates higher mechanical structural stability of the palladium film and fewer defects in the composite membrane material. Specifically, this is determined by measuring the hydrogen permeation / diffusion rate (J / N2) of the membrane. H2 The nitrogen permeation diffusion rate at the defect under the same conditions (573 K, 0.5 MPa transmembrane pressure difference) (J) N2 According to the formula α(H2 / N2)=J H2 / J N2 The above measurement methods were used to obtain the result.

[0269] Table 10

[0270]

[0271] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composite palladium-based alloy material, characterized in that, The composite palladium-based alloy material is composed of Pd and Group IB metals, and the molar ratio of Pd to Group IB metals is 1:(0.05-9). In the XRD pattern of the composite palladium-based alloy material, 2θ = 40° o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.017–0.0426, and 2θ = 46. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.017–0.0481, and 2θ = 69. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.029–0.0557, and 2θ = 83. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.031–0.0603, and 2θ = 87. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at that location is in the range of 0.032–0.0643. Alternatively, in the XRD pattern of the composite palladium-based alloy material, 2θ = 43. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.017–0.041, and 2θ = 53. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.024–0.055, and 2θ = 62. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.036–0.066, and 2θ = 70°. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.047–0.068, and 2θ = 79. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at that location is in the range of 0.051–0.

074. The crystal phase structure analysis of the composite palladium-based alloy material was performed using an X-ray diffractometer. The experimental conditions were Cu... K α ray, λ = 0.1543 nm, tube voltage 40 kV, current 40 mA, diffraction angle 2 θ The scanning range is 10-90. o ; The method for testing the half-peak width (WHM) of composite palladium-based alloy materials is as follows: based on the X-ray diffraction test results, combined with HighScore Plus software analysis, the radian value of the WHM is obtained.

2. The composite palladium-based alloy material according to claim 1, wherein, 2θ=40 o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.017–0.02, and 2θ = 46. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.017–0.034, and 2θ = 69. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.029–0.036, and 2θ = 83. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at this location is in the range of 0.031–0.039, and 2θ = 87. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at that location is in the range of 0.032–0.

041. And / or, the Group IB metal element is Au, and in the XRD pattern of the composite palladium-based alloy material, 2θ = 40°. o ±1 o The full width at half maximum (FWHM1, 2θ) of the characteristic peak at this location is 46. o ±1 o The full width at half maximum (FWHM2, 2θ) of the characteristic peak at this location is 69. o ±1 o The full width at half maximum (FWHM3) of the characteristic peak at point 2θ = 83 o ±1 o The full width at half maximum (FWHM4) of the characteristic peak at point FWHM4, 2θ = 87 o ±1 o The full width at half maximum (FWHM5) of the characteristic peak at point FWHM5 satisfies the following equation: FWHM x =(FWHM x-1 +FWHM x+1 ) / 2 ± W式I Where x = 2, 3 or 4, and W is 0.0003-0.0064.

3. The composite palladium-based alloy material according to claim 1, wherein, The lattice parameter k of the composite palladium-based alloy material is 0.3836-0.4369 nm.

4. The composite palladium-based alloy material according to claim 1, wherein, The lattice parameter k of the composite palladium-based alloy material is 0.4075-0.4289 nm.

5. The composite palladium-based alloy material according to any one of claims 1-4, wherein, The crystal structure of the composite palladium-based alloy material is face-centered cubic close-packed or body-centered cubic. And / or, the Group IB metal element is at least one of Cu, Ag and Au; And / or, the molar ratio of Pd to Group IB metals is 1:(0.1-1.6). And / or, the composite palladium-based alloy material further contains Ni, and the molar ratio of Pd to Ni is 1:(0.35-0.65); And / or, the thickness of the composite palladium-based alloy material is 0.5-30µm.

6. The composite palladium-based alloy material according to any one of claims 1-4, wherein, The molar ratio of Pd to Group IB metals is 1:(0.2-0.8).

7. The composite palladium-based alloy material according to any one of claims 1-4, wherein, The thickness of the composite palladium-based alloy material is 5-15µm.

8. A method for preparing composite palladium-based alloy materials, characterized in that, The method includes: depositing Pd, a Group IB metal and optional Ni on a support, and then alloying the support on which Pd, Group IB metal and optional Ni have been deposited, wherein the molar ratio of Pd to Group IB metal is 1:(0.05-9). The alloying process is as follows: in an activating atmosphere, heat treatment is first performed at 350℃-650℃ and a pressure of 0.12-0.75MPa, and then the temperature is reduced to below 200℃ at a rate greater than 5℃ / min. The gas providing the activating atmosphere includes alkaline gas.

9. The method according to claim 8, wherein, The Group IB metal is at least one of Cu, Ag, and Au; And / or, the molar ratio of Pd to Group IB metals is 1:(0.1-1.6). And / or, the molar ratio of Pd to Ni is 1:(0.35-0.65); And / or, the alloying treatment is carried out by: treating in an activating atmosphere at a temperature of 350-650℃ and a pressure of 0.12-0.75MPa for 2-10 hours; then cooling to 100-200℃ at a rate of 25-150℃ / min. And / or, the content of alkaline gas in the gas providing the activating atmosphere is greater than or equal to 20% by volume; And / or, the alkaline gas is selected from at least one of ethylenediamine, NH3, PH3 and N2H4; And / or, the total thickness of the Pd and Group IB metals deposited on the support is 0.5-30µm; And / or, the thickness of the support is 0.1-20 mm.

10. The method according to claim 8, wherein, The molar ratio of Pd to Group IB metals is 1:(0.2-0.8).

11. The method according to claim 8, wherein, The total thickness of the Pd and Group IB metals deposited on the support is 5-15µm.

12. The method according to claim 8, wherein, The thickness of the support is 2-5mm.

13. The composite palladium-based alloy material prepared by the method according to any one of claims 8-12.

14. A composite membrane, characterized in that, The composite membrane comprises a composite palladium-based alloy material and a silica-alumina molecular sieve modified with hydrophobic groups attached to the surface of the composite palladium-based alloy material, wherein the composite palladium-based alloy material is the composite palladium-based alloy material according to any one of claims 1-7 and 13.

15. The composite membrane according to claim 14, wherein, The water contact angle of the composite membrane is greater than or equal to 90°. o ; And / or, the composite membrane is a tubular membrane; And / or, the composite membrane further includes a support, on which the composite palladium-based alloy material is attached, and the thickness of the support is 0.1-20 mm.

16. The composite membrane according to claim 14, wherein, The water contact angle of the composite membrane is greater than or equal to 105°. o .

17. The composite membrane according to claim 14, wherein, The composite membrane also includes a support body, on which the composite palladium-based alloy material is attached, and the thickness of the support body is 2-5 mm.

18. The composite membrane according to claim 14, wherein, The hydrophobic group-modified silica-alumina molecular sieve 29 In the Si MAS NMR spectrum, the ratio of the peak areas of the peaks with chemical shifts near -113 ppm and -103 ppm is 6-12. And / or, the hydrophobic group-modified silica-alumina molecular sieve is at least one of the following: hydrophobic group-modified ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-34, 3A molecular sieve, 4A molecular sieve, 5A molecular sieve, SAPO-31, SAPO-34, SAPO-44, RUB-13, MCM-68, Y-type molecular sieve and mordenite; And / or, the thickness of the hydrophobic group-modified silica-alumina molecular sieve is 1-100µm; And / or, the silica-alumina molar ratio of the hydrophobic group-modified silica-alumina molecular sieves is (2-100):1; the average particle size is 60-380 nm; the average pore size is 0.3-230 nm; and the specific surface area is 35-750 m². 2 / g; crystallinity greater than or equal to 90%.

19. The composite membrane according to claim 14, wherein, The thickness of the hydrophobic group-modified silica-alumina molecular sieve is 5-30µm.

20. The composite membrane according to claim 14, wherein, The molar ratio of silicon to aluminum in the hydrophobic group-modified silica-alumina molecular sieve is (2.5-20):

1.

21. The composite membrane according to claim 14, wherein, The average particle size of the hydrophobic group-modified silica-alumina molecular sieve is 150-200 nm.

22. The composite membrane according to claim 14, wherein, The average pore size of the hydrophobic group-modified silica-alumina molecular sieve is 1-18 nm.

23. The composite membrane according to claim 14, wherein, The specific surface area of ​​hydrophobic group-modified silica-alumina molecular sieves is 65-480 m². 2 / g.

24. The composite membrane according to claim 14, wherein, The crystallinity of the hydrophobic group-modified silica-alumina molecular sieve is 95-99%.

25. The composite membrane according to claim 14, wherein, The composite membrane also includes VIB metal oxide nanoparticles attached to the surface of a silica-alumina molecular sieve modified with hydrophobic groups, wherein the average particle size of the VIB metal oxide nanoparticles is 50-200 nm.

26. The composite membrane according to claim 25, wherein, The content of the group VIB metal oxide nanoparticles is such that the molar ratio between the group VIB metal and Pd is 0.01-0.

5.

27. The application of the composite membrane according to any one of claims 14-26 in steam reforming for hydrogen production.

28. A method for producing hydrogen by steam reforming, characterized in that, The method includes: In the presence of a catalyst, alcohol and water vapor are introduced into a first reactor equipped with a first composite membrane for a reforming reaction, wherein the first composite membrane is the composite membrane described in any one of claims 14-26; the alcohol and water vapor are introduced from the side of the silica-alumina molecular sieve modified with hydrophobic groups near the first composite membrane, so that the hydrogen gas generated by the reforming reaction passes through the first composite membrane via the side of the silica-alumina molecular sieve modified with hydrophobic groups and is removed from the first reactor; Optionally, the method further includes introducing gas that has not permeated the first composite membrane into a second reactor equipped with a second composite membrane for carbon dioxide capture or conversion.

29. The method according to claim 28, wherein, The method for producing hydrogen through steam reforming may further include, based on the hydrogen permeation-diffusion rate required for carbon dioxide capture or conversion, J. H2 Determine the lattice parameter k of the palladium film; provide a second composite film comprising the palladium film having the stated lattice parameter; perform carbon dioxide capture or conversion in the presence of the provided second composite film; wherein the hydrogen permeation diffusion rate J H2 Equation II is satisfied with the lattice parameter k: Formula II In Equation II, the unit of JH2 is mol·m⁻²·s⁻¹; The unit of k is nm; n is the number of metal types contained in the palladium film; Ma is the average relative atomic mass of n alloys, expressed in g / mol. Mi is the relative atomic mass of the i-th metal, expressed in g / mol. ρa is the average density of the n alloys, in kg / m3; ρi is the density of the i-th metal, in kg / m3; d represents the thickness of the palladium film, in meters (m). b is the correction factor, and its value ranges from 0.5 to 3.

30. The method according to claim 28, wherein, The second composite membrane includes a palladium membrane and a silica-alumina molecular sieve loaded with sodium-modified nano-Fe3O4 attached to the surface of the palladium membrane.

31. The method according to claim 30, wherein, The silica-alumina molecular sieve in the second composite membrane is at least one of HZSM-5, HZSM-11, HZSM-12, HZSM-23, HZSM-34, HY, HMCM-22, HBEA, and HMOR; And / or, the thickness of the silica-alumina molecular sieve loaded with sodium-modified nano-Fe3O4 is 100-3750 nm; And / or, the silica-alumina molar ratio of the silica-alumina molecular sieve in the second composite membrane is (2-50):1; the average particle size is 50-420 nm; the average pore size is 0.25-225 nm; and the specific surface area is 25-600 m². 2 / g; Crystallinity greater than or equal to 92%; And / or, the average particle size of the sodium-modified nano-Fe3O4 in the second composite film is 5-300 nm; And / or, the loading of sodium-modified nano-Fe3O4 in the second composite film is such that the molar ratio of Pd to Fe is 1:(0.001-0.1). And / or, the molar ratio of Na to Fe in the sodium-modified nano Fe3O4 in the second composite film is 1:(1-10).

32. The method according to claim 30, wherein, The thickness of the silica-alumina molecular sieve loaded with sodium-modified nano-Fe3O4 is 350-1500 nm.

33. The method according to claim 30, wherein, The silicon-aluminum molar ratio of the silicon-aluminum molecular sieve in the second composite membrane is (5-20):

1.

34. The method according to claim 30, wherein, The average particle size of the silica-alumina molecular sieve in the second composite membrane is 150-300 nm.

35. The method according to claim 30, wherein, The average pore size of the silica-alumina molecular sieve in the second composite membrane is 0.75-35 nm.

36. The method of claim 30, wherein, The specific surface area of ​​the silica-alumina molecular sieve in the second composite membrane is 50-500 m². 2 / g.

37. The method of claim 30, wherein, The crystallinity of the silica-alumina molecular sieve in the second composite membrane is 96-99%.

38. The method according to claim 30, wherein, The average particle size of the sodium-modified nano-Fe3O4 in the second composite film is 10-100 nm.

39. The method according to claim 30, wherein, The loading of sodium-modified nano-Fe3O4 in the second composite film results in a molar ratio of Pd to Fe of 1:(0.001-0.03).

40. The method of claim 30, wherein, In the second composite membrane, the molar ratio of Na to Fe in the sodium-modified nano Fe3O4 is 1:(3-6).

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