Copper-containing composite membranes including titanium-silicon molecular sieve layers, their preparation methods, and their application in the preparation of propylene oxide.

Abstract

This invention relates to the field of propylene oxide preparation, and discloses a copper-containing composite membrane including a titanium-silicon molecular sieve layer, its preparation method, and its application in propylene oxide preparation. The composite membrane comprises a composite palladium-based alloy material and a titanium-silicon molecular sieve loaded with noble metals attached to the surface of the composite palladium-based alloy material. The composite palladium-based alloy material contains Pd and Cu, with a molar ratio of Pd to Cu of 1:(0.8-1.3). The composite palladium-based alloy material has a body-centered cubic crystal structure with a lattice parameter k of 0.2752-0.3009 nm. In the XRD pattern of the composite palladium-based alloy material, the full width at half maximum (FWHM) of at least one characteristic peak of 2θ in the range of 35°-90° is less than or equal to 0.1602. The composite membrane of this invention significantly reduces the mass transfer resistance in the direct vapor-phase epoxidation reaction of propylene, and improves the utilization rate of each raw material and the selectivity of propylene oxide.

Description

Technical Field

[0001] This invention relates to the field of propylene oxide preparation, specifically to a copper-containing composite membrane including a titanium-silicon molecular sieve layer, its preparation method, and its application in the preparation of propylene oxide. Background Technology

[0002] Propylene oxide is a high-value chemical globally, widely used in food, textiles, pharmaceuticals, and chemicals. Currently, the main industrial methods for producing propylene oxide include the chlorohydrin process, the co-oxidation process, and the direct oxidation process. The chlorohydrin process generates large amounts of chlorine-containing wastewater that pollutes the environment, contradicting current green environmental protection principles. The co-oxidation process requires high-quality raw materials, its product is heavily influenced by co-products, and it is lengthy and costly. The direct oxidation process uses hydrogen peroxide as an oxidant, but its biggest challenge lies in the supply of hydrogen peroxide. Hydrogen peroxide is chemically reactive and expensive, and it is lost during storage and transportation due to decomposition, reducing its utilization efficiency and increasing production costs; it also poses significant safety hazards.

[0003] In recent years, related studies have found that a one-step gas-phase direct synthesis of propylene oxide using hydrogen, oxygen, and propylene as raw materials can achieve a selectivity of over 90%. However, hydrogen is a flammable gas, and its explosive concentration when mixed with oxygen at room temperature and pressure is 4-74%. Therefore, the explosion risk caused by the direct mixing of hydrogen and oxygen, the low utilization rate of hydrogen, and the high cost of preparing precious metal catalysts limit the industrial scale-up and promotion of this technology. To address the explosion risk caused by the direct mixing of hydrogen and oxygen and the issue of hydrogen utilization, some studies have proposed a porous membrane contactor design. However, because this porous membrane has almost no selectivity for hydrogen and oxygen, it cannot balance the pressure on both sides of the membrane. The safety hazards caused by the mutual permeation of hydrogen and oxygen become a difficult problem to solve, and the above method is also accompanied by the problem of low hydrogen utilization. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems existing in the prior art and provide a copper-containing composite membrane including a titanium-silicon molecular sieve layer, its preparation method, and its application in the preparation of propylene oxide.

[0005] To achieve the above objectives, a first aspect of the present invention provides a copper-containing composite membrane comprising a titanium-silicon molecular sieve layer. The composite membrane comprises a composite palladium-based alloy material and a titanium-silicon molecular sieve loaded with a noble metal attached to the surface of the composite palladium-based alloy material. The composite palladium-based alloy material contains Pd and Cu, and the molar ratio of Pd to Cu is 1:(0.8-1.3). The composite palladium-based alloy material has a body-centered cubic crystal structure with a lattice parameter k of 0.2752-0.3009 nm. In the XRD pattern of the composite palladium-based alloy material, the full width at half maximum (FWHM) of at least one characteristic peak of 2θ in the range of 35°-90° is less than or equal to 0.1602.

[0006] A second aspect of the present invention provides a method for preparing a copper-containing composite membrane comprising a titanium-silicon molecular sieve layer, the method comprising:

[0007] (1) Pd and Cu are deposited on the support, and then the support with Pd and Cu deposited is alloyed.

[0008] The alloying treatment is performed as follows: after treatment in an activating atmosphere at a temperature of 570-600℃ and a pressure of 0.37-0.52MPa for 3-5 hours, the temperature is reduced to 100-150℃ at a rate of 70-100℃ / min. The activating atmosphere consists of gases including H2, N2, and NH3, and the volume ratio of H2, N2, and NH3 is 1:(0.2-0.5):(0.02-0.1).

[0009] (2) The alloyed material is placed in a solution of a precursor containing titanium-silicon molecular sieve and subjected to hydrothermal crystallization, drying and calcination in sequence to obtain a composite membrane precursor.

[0010] (3) The composite membrane precursor is impregnated in a reducing atmosphere using an alkaline solution containing a noble metal precursor and an organic dispersant.

[0011] A third aspect of the present invention provides a composite membrane prepared by the method described above.

[0012] The fourth aspect of this invention provides a composite palladium-based alloy material.

[0013] The fifth aspect of the present invention provides the application of the composite membrane described above in the preparation of propylene oxide.

[0014] Through the above technical solution, this invention achieves the coupled preparation of a palladium-based alloy membrane and a titanium-silicon molecular sieve membrane loaded with noble metals, enabling the efficient synthesis of propylene oxide at the composite membrane interface. This significantly reduces the mass transfer resistance in the direct gas-phase epoxidation reaction of propylene, improving the utilization rate of each raw material and the selectivity of propylene oxide. Compared to existing technologies, the composite membrane obtained by this invention is easier to install and disassemble during the reaction process, has a longer service life, and, being a pure gas-phase reaction system, the catalyst is integrated into the composite membrane, eliminating the problem of solid powder separation and simplifying product separation after the reaction. This invention does not require additional energy sources; using the composite membrane material as a catalyst, it catalyzes the direct gas-phase synthesis of propylene oxide from propylene, hydrogen, and oxygen, offering advantages such as a simple process flow and low energy consumption. During the reaction, hydrogen and oxygen are physically isolated by the dense palladium-based composite membrane, avoiding the explosion risk caused by direct mixing. Simultaneously, the reaction system does not generate organic byproducts such as carbon dioxide, acrolein, acetone, and propionic acid, nor does it require the addition of stabilizers such as phosphoric acid and methanol (i.e., the method of this invention does not require the addition of stabilizers to the reaction system for preparing propylene oxide), making the process safe and environmentally friendly. Attached Figure Description

[0015] Figure 1 These are scanning electron microscope (SEM) images of the palladium-based alloy film before (a) and after (b) the loading of Au / TS-1 composite catalyst material;

[0016] Figure 2 This is a transmission electron microscope (TEM) image of the Au / TS-1 composite catalytic material (i.e., gold-loaded titanium-silicon molecular sieve) peeled off from the palladium film.

[0017] Figure 3 The results are the physical adsorption characterization (BET) of the Au / TS-1 composite catalyst material stripped from the palladium film.

[0018] Figure 4 The results are the Fourier Transform Infrared (FTIR) characterization results of the Au / TS-1 composite catalytic material stripped from the palladium film.

[0019] Figure 5 The results are shown in the UV-Vis spectroscopic characterization of the Au / TS-1 composite catalyst material stripped from the palladium film.

[0020] Figure 6 The results are X-ray diffraction (XRD) characterization of the Au / TS-1 composite catalyst material stripped from the palladium film.

[0021] Figure 7 This is a schematic diagram of the direct vapor-phase epoxidation of propylene catalyzed by a palladium-copper-titanium-silicon molecular sieve-Au nanoparticle composite membrane. Detailed Implementation

[0022] 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.

[0023] The first aspect of the present invention provides a copper-containing composite membrane including a titanium-silicon molecular sieve layer. The composite membrane includes a composite palladium-based alloy material and a titanium-silicon molecular sieve loaded with a noble metal attached to the surface of the composite palladium-based alloy material. The composite palladium-based alloy material contains Pd and Cu, and the molar ratio of Pd to Cu is 1:(0.8-1.3). The crystal structure of the composite palladium-based alloy material is body-centered cubic, and the lattice parameter k is 0.2752-0.3009 nm. In the XRD pattern of the composite palladium-based alloy material, the full width at half maximum (FWHM) of at least one characteristic peak of 2θ in the range of 35°-90° is less than or equal to 0.1602.

[0024] In this invention, "body-centered cubic packing" refers to a close-packed arrangement in a cubic crystal system, which includes two lattice points, one at the 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. The eight atoms at the vertices are tangent to the central atom.

[0025] In this invention, "lattice parameter k" refers to the physical dimensions of a unit cell in a crystal lattice, representing a fundamental structural parameter of a 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. Based on the morphological distribution of the Bravais lattice, in the cubic crystal structure (body-centered cubic packing) 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).

[0026] According to the present invention, preferably, the full width at half maximum (FWHM) of all characteristic peaks of 2θ in the range of 35°-90° in the XRD pattern of the composite palladium-based alloy material is less than or equal to 0.1602.

[0027] According to the present invention, preferably, in the XRD pattern of the composite palladium-based alloy material, the full width at half maximum (FWHM) of the characteristic peak at 2θ = 43° ± 1° (i.e., the characteristic peak of crystal plane (110)) is less than or equal to 0.0524 (e.g., 0.0524, 0.05, 0.045, 0.04, 0.035, 0.03, 0.025, 0.02, 0.0175, 0.015, 0.01, and any two of the above points), more preferably 0.017-0.031, 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 0.0698 (e.g., 0.0698, 0.06, 0.0524, 0.01, and any two of the above points). 5. 0.045, 0.04, 0.035, 0.0349, 0.03, 0.025, 0.02, 0.015, 0.01, and any two of the above points), more preferably 0.038-0.057, or the full width at half maximum (FWHM) of the characteristic peak at 2θ = 62° ± 1° (i.e., the characteristic peak of the crystal plane (200)) is less than or equal to 0.1047 (e.g., 0.1047, 0.09, 0.08, 0.07, 0.06, 0.0524, 0.05, 0.045, 0.04, 0.035, 0.03, 0.025, 0.02, 0.015, 0.01, and any two of the above points), more preferably 0.055. -0.066, 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 0.1222 (e.g., 0.1222, 0.12, 0.11, 0.1, 0.09, 0.0873, 0.08, 0.07, 0.06, 0.0698, 0.06, 0.0524, 0.05, 0.045, 0.04, 0.035, 0.03, 0.025, 0.02, 0.015, 0.01, and any two of the above points), more preferably 0.072-0.11, 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 0.1222 (e.g., 0.1222, 0.12, 0.11, 0.11, 0.072-0.11, or the full width at half maximum (FWHM) of the characteristic peak at 2θ = 79° ± 1° is less than or equal to 0.1222 (e.g., 0.1222, 0.12, 0.11, 0.11, 0.12 ... The value is preferably 0.08-0.11 (e.g., 0.1571, 0.14, 0.13, 0.12, 0.11, 0.1047, 0.1, 0.09, 0.0873, 0.08, 0.07, 0.06, 0.0524, 0.05, 0.045, 0.04, 0.035, 0.03, 0.025, 0.02, 0.015, 0.01, and any two of the above points). "Half-peak width" is defined as the peak width at half the peak 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-peak width. When the palladium-copper alloy material has no characteristic peak at the corresponding 2θ, the half-peak width is considered to be 0.

[0028] According to the present invention, preferably, the thickness of the composite palladium-based alloy material is 0.5-30 μm (e.g., 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, and any two of the above), more preferably 5-15 μm, and even more preferably 6-9 μm.

[0029] According to the present invention, preferably, the loading of noble metals in the titanium-silicon molecular sieve loaded with noble metals is 0.01-10 wt%, more preferably 0.01-2 wt%.

[0030] According to the present invention, preferably, the precious metal is selected from gold.

[0031] According to the present invention, preferably, the titanium-silicon molecular sieve loaded with noble metal is at least one of TS-1, TS-2, Ti-β molecular sieve, Ti-MCM-41, Ti-MCM-48, Ti-TUD and Ti-HMS loaded with noble metal.

[0032] According to the present invention, preferably, the thickness of the titanium-silicon molecular sieve loaded with noble metal is 1-100 μm (e.g., 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, and any two of the above), preferably 5-30 μm, and more preferably 8-13 μm.

[0033] According to the present invention, preferably, the silicon-to-titanium molar ratio of the titanium-silicon molecular sieve loaded with noble metal is (50-400):1, more preferably (80-200):1; the average particle size is 10-300 nm, more preferably 50-150 nm; the average pore size is 0.1-100 nm, more preferably 3-20 nm; and the specific surface area is 10-700 m². 2 / g, preferably 50-450m 2 / g; crystallinity greater than or equal to 88%, preferably 92-97%.

[0034] According to the present invention, preferably, the average particle size of the noble metal in the titanium-silicon molecular sieve loaded with noble metal is 1-5 nm, more preferably 1.7-3.2 nm.

[0035] According to the present invention, preferably, the composite membrane is a tubular membrane.

[0036] According to the present invention, preferably, the composite membrane further includes a support body, the composite palladium-based alloy material is attached to the support body, and the thickness of the support body is 0.1-20 mm (for example, 0.1 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 15 mm, 20 mm, and any two of the above), preferably 2-5 mm.

[0037] A second aspect of the present invention provides a method for preparing a copper-containing composite membrane comprising a titanium-silicon molecular sieve layer, characterized in that the method comprises:

[0038] (1) Pd and Cu are deposited on the support, and then the support with Pd and Cu deposited is alloyed, wherein the molar ratio of Pd to Cu is 1:(0.8-1.3).

[0039] The alloying treatment is performed as follows: after treatment in an activating atmosphere at a temperature of 570-600℃ and a pressure of 0.37-0.52MPa for 3-5 hours, the temperature is reduced to 100-150℃ at a rate of 70-100℃ / min. The activating atmosphere consists of gases including H2, N2, and NH3, and the volume ratio of H2, N2, and NH3 is 1:(0.2-0.5):(0.02-0.1).

[0040] (2) The alloyed material is placed in a solution of a precursor containing titanium-silicon molecular sieve and subjected to hydrothermal crystallization, drying and calcination in sequence to obtain a composite membrane precursor.

[0041] (3) The composite membrane precursor is impregnated with an alkaline solution containing a noble metal precursor and an organic dispersant, and then the noble metal in the noble metal precursor is converted into a reduced state in a reducing atmosphere.

[0042] The present invention reduces the activation energy of hydrogen permeation of the membrane material by performing heat treatment at a specific temperature and then cooling it at a specific rate, thereby improving the hydrogen permeation efficiency and stability of the membrane material (the half-peak width corresponding to the characteristic peak is small). The use of ammonia will further improve the hydrogen permeability and stability of the membrane material.

[0043] According to the present invention, preferably, the total thickness of Pd and Cu deposited on the support is 0.5-30 μm (e.g., 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, and any two of the above), preferably 5-15 μm, and more preferably 6-9 μm.

[0044] According to the present invention, preferably, the thickness of the support is 0.1-20 mm (e.g., 0.1 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 15 mm, 20 mm, and any two of the above), 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 to reduce the amount of palladium used (reducing costs), preferably, the support is a porous support, which can be 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 distribution 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 distribution ranging from 25-66% and an average pore size of 0.12-0.4 μm. The porous stainless steel material can be 316L(Fe₂O₃). 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.

[0045] According to the present invention, preferably, the precursor solution of the titanium-containing silicon molecular sieve contains a silicon source, a titanium source, a template agent, water, and optionally a surfactant.

[0046] According to the present invention, preferably, the molar ratio of the silicon source, titanium source, template agent, water and surfactant is 100:(0.25-2):(1-50):(10-3000):(0-18), and more preferably 100:(0.5-1.25):(10-30):(20-1500):(0.1-6).

[0047] According to the present invention, preferably, the amount of the titanium-silicon molecular sieve precursor solution used is 0.1-1.5 ml per 1 g of alloyed material.

[0048] According to the present invention, preferably, the silicon source is at least one of silicate ester, silicate and silicon dioxide, and more preferably selected from at least one of tetrabutyl orthosilicate, tetraethyl orthosilicate, sodium silicate, potassium silicate, silica sol and water glass.

[0049] According to the present invention, preferably, the titanium source is at least one of titanate, titanium salt, titanium oxysulfate and titanium difluoride, and more preferably selected from at least one of tetrabutyl titanate, tetraethyl titanate, titanium tetrachloride, titanium isopropoxide, titanium sulfate, titanium oxysulfate and titanium difluoride.

[0050] According to the present invention, preferably, the template agent is at least one of tetraalkylammonium hydroxide, alkylamine and tetraalkylammonium halide, and more preferably selected from at least one of tetrabutylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium hydroxide, triethylamine, hexadecyltrimethylammonium bromide and isopropylamine.

[0051] According to the present invention, preferably, the surfactant is at least one of nonionic surfactants, and more preferably selected from at least one of Tween-20, Tween-21, Tween-40, Tween-60, Tween-80, Tween-85, polyethylene glycol, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ester, polyoxyethylene alkylamine, polyoxyethylene alkylamide, and polyethers.

[0052] According to the present invention, preferably, the hydrothermal crystallization method is to first perform aging and then crystallize, wherein the aging conditions include: aging temperature of 60-90℃ and aging time of 3-6h; and the crystallization conditions include: crystallization temperature of 150-180℃ and crystallization time of 36-72h.

[0053] The aging process of the present invention can be carried out under stirring conditions, preferably at a stirring rate of 800-1300 rpm.

[0054] The crystallization of the present invention can be carried out under stirring conditions, preferably with an aging stirring rate of 10-25 rpm.

[0055] According to the present invention, preferably, the drying conditions include: a drying temperature of 30-80°C and a drying time of 8-18 hours.

[0056] According to the present invention, preferably, the calcination conditions include: calcination temperature of 500-650℃ and calcination time of 3-6h.

[0057] According to the present invention, preferably, the content of the noble metal precursor, calculated as gold element, in the alkaline solution containing the noble metal precursor and the organic dispersant is 0.001-3 mol / L (e.g., 0.001 mol / L, 0.015 mol / L, 0.02 mol / L, 0.025 mol / L, 0.03 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, and any two of the above ranges), more preferably 0.02-0.03 mol / L.

[0058] According to the present invention, preferably, the noble metal precursor is selected from at least one of chloroauric acid, gold hydroxide colloid and EDTA-Au complex.

[0059] According to the present invention, preferably, the content of the organic dispersant in the alkaline solution containing the noble metal precursor and the organic dispersant is 0.01-1 vol% (e.g., 0.01 vol%, 0.1 vol%, 0.15 vol%, 0.2 vol%, 0.25 vol%, 0.3 vol%, 0.4 vol%, 0.5 vol%, 0.6 vol%, 1 vol%, and any two of the above), more preferably 0.15-0.25 vol%.

[0060] According to the present invention, preferably, the organic dispersant is selected from at least one of ethylene glycol, ethylenediamine, urea, bipyridine, and glycerol.

[0061] According to the present invention, preferably, the pH value of the alkaline solution containing the noble metal precursor and the organic dispersant is greater than or equal to 5.

[0062] According to the present invention, preferably, the amount of alkaline solution containing noble metal precursor and organic dispersant is 0.1-1.5 ml relative to 1 g of alloyed material.

[0063] According to the present invention, preferably, the impregnation conditions include: a temperature of 0-85°C (e.g., 0°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, and any two of the above), preferably 30-40°C; a pH of 5.2-10.3 (e.g., 5.2, 5.5, 6, 6.5, 7, 7.5, 8, 9, 10, 10.3, and any two of the above), preferably 7-8; and an impregnation time of 8-30h (e.g., 8h, 10h, 15h, 20h, 24h, 30h), preferably 20-24h.

[0064] According to the present invention, preferably, step (3) includes: impregnating the composite membrane precursor with an alkaline solution containing a noble metal precursor and an organic dispersant, then drying it under vacuum conditions (vacuum drying temperature is 30-150°C, pressure is 2-101 kPa(G)) for 20-30 h, and then reducing it in a hydrogen-nitrogen mixture with a hydrogen volume content of 5-20% at 180-220°C for 2-4 h to convert the noble metal in the noble metal precursor into a reduced state.

[0065] A third aspect of the present invention provides a composite membrane prepared by the method described above.

[0066] The fourth aspect of this invention provides a composite palladium-based alloy material.

[0067] The fifth aspect of the present invention provides the application of the composite membrane described above in the preparation of propylene oxide.

[0068] 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 or the like are selectively loaded only on the outer surface of the support, and the PTFE material is peeled off before application or performance testing.

[0069] Examples A1-A4

[0070] (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. A vacuum pump was used to clean the residual ethanol in the pores. Finally, the support was placed in an oven and dried at 423 K for 4 hours. Based on Faraday's law, Pd and Cu were deposited on the support using electroplating, with the Pd to Cu molar ratio M as shown in Table 1. The effective film area was 25 cm². 2 The electroplating conditions were as follows: using a conductive layer carrier as the working electrode, a platinum electrode (Pd plated) and a waveguide with a copper content of 99.999% (Cu plated) as the counter electrodes, and a saturated calomel electrode as the reference electrode, the metal ions (Pd) in the plating bath were concentrated at 30°C. 2+ Cu 2+The concentration of the solution was 0.01-0.1 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; 0.5-1.5 ml / min: 0.075 mol / L copper nitrate (Cu(NO3)2) 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 program, the working electrode was treated in distilled water at 95℃ for 15 min before being removed. The Pd and Cu deposited support was subjected to high-temperature alloying treatment. The alloying treatment method was as follows: after treatment at temperature T1 and pressure P in an activating atmosphere for a period of time (t); the temperature was then reduced to T2 at a rate V. The activating atmosphere consisted of H2, N2, and NH3, with the volume ratio of H2, N2, and NH3 = R1. The amount of activating atmosphere gas provided was such that the alloying pressure was P. See Table 1 for details of the parameters.

[0071] (2) The alloyed material obtained in step (1) was placed in the precursor solution of TS-1 molecular sieve for hydrothermal crystallization (aging and crystallization were performed in sequence), drying and calcination. The molar ratio R2 of silicon source, titanium source, template agent, water and nonionic surfactant and the conditions of each step are shown in Table 1 to obtain the composite membrane precursor. In the precursor solution of TS-1 molecular sieve, tetrapropylammonium hydroxide (TPAOH) is the template agent, tetrabutyl orthosilicate (TEOS) is the silicon source, tetrabutyl titanate (TBOT) is the titanium source and Tween-20 is the nonionic surfactant. The amount of titanium-silicon molecular sieve precursor solution used is 0.75 ml per 1 g of alloyed material.

[0072] (3) At 35°C, the obtained composite membrane precursor was immersed in a solution of a gold-containing precursor prepared by adjusting the pH of 0.025 mol / L chloroauric acid solution to 7.6 with 0.1 mol / L sodium hydroxide and adding 0.2 vol% ethylene glycol as an organic dispersant for 24 h (the volume of the solution was 0.5 ml relative to 1 g of composite palladium-based alloy material), so that the gold nanoparticles (at this time, the gold nanoparticles are in Au(OH)2) x The composite membrane material (existing in the form of a complex) is fully impregnated and dispersed into the molecular sieve pore structure. The impregnated composite membrane material is dried under vacuum conditions (vacuum drying temperature of 80℃ and pressure of 20kPa(G)) for 28h to remove residual moisture on the surface. Then, the above material is treated at 200℃ for 3h in a hydrogen-nitrogen mixed atmosphere containing 15 vol.% hydrogen to reduce the gold nanoparticles to the zero-valent metallic state (Au).

[0073] Example A5

[0074] The procedure was carried out in accordance with Example A1, except that the molar ratio of Pd to Cu was changed to 1:0.8.

[0075] Example A6

[0076] The procedure was carried out in accordance with Example A1, except that the molar ratio of Pd to Cu was changed to 1:1.3.

[0077] Comparative Example AD1

[0078] The process is carried out in accordance with Example A1, except that the gas providing the activating atmosphere is only N2.

[0079] Comparative Example AD2

[0080] The process is carried out in accordance with Example A1, except that the gas providing the activating atmosphere is only H2.

[0081] Comparative Example AD3

[0082] The process is carried out in accordance with Example A1, except that the gas providing the activating atmosphere is only argon.

[0083] Comparative Example AD4

[0084] 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).

[0085] Comparative Example AD5

[0086] 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.

[0087] Comparative Example AD6

[0088] The process was carried out in accordance with Example A1, except that the alloying temperature T1 = 700°C.

[0089] Comparative Example AD7

[0090] The alloying process was carried out in accordance with Example A1, except that the alloying pressure P = 0.1 MPa.

[0091] Table 1

[0092]

[0093]

[0094] Test case

[0095] (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 2.

[0096] 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.

[0097] d=λ / 2sinθ

[0098] Where λ corresponds to Cu K α The wavelength of the radiation, θ is the angle of the diffraction peak.

[0099] 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.

[0100] 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 ) 0.5 The interplanar spacing (d1 d2 d3) of the corresponding characteristic crystal planes is calculated. That is, the PdCu alloy material obtained in this invention belongs to the body-centered cubic (BCC) structure, and its characteristic crystal planes include (110), (111), (200), (210), and (211). 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 PdCu alloy material obtained in this invention, the (110) plane corresponds to the characteristic peak at 2θ = 43° ± 1°, the (111) plane corresponds to the characteristic peak at 2θ = 53° ± 1°, the (200) plane corresponds to the characteristic peak at 2θ = 62° ± 1°, the (210) plane corresponds to the characteristic peak at 2θ = 70° ± 1°, and the (211) plane corresponds to the characteristic peak at 2θ = 79° ± 1°. By using HighScorePlus analysis software and combining the peak intensities of the above characteristic crystal planes, the lattice parameter k of the corresponding material is calculated.

[0101] 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 palladium-based alloy material prepared by this invention was smooth and free of defects.

[0102] The method for testing the half-peak width (WHM) of composite palladium-based alloy materials is as follows: based on the XRD spectrum test results, combined with HighScore Plus software analysis, the radian value of the WHM is obtained.

[0103] (II) Solid-phase exfoliation was performed on the composite membranes 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 gold-loaded titanium-silicon molecular sieve attached to the surface of the composite palladium-based alloy material are obtained, as shown in Table 2.

[0104] Gold-loaded titanium-silicon molecular sieves were 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 TS-1 molecular sieve with a double ten-membered ring cross-channel structure (MFI structure). Figure 6 The 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 titanium-silicon molecular sieves. The XRD patterns of the molecular sieves in each example are similar to those in Example A1. Figure 6 Similarly, this indicates that the obtained molecular sieves are all TS-1 titanium-silicon molecular sieves;

[0105] Methods for determining the specific surface area and average pore size of gold-loaded titanium-silicon molecular sieves: The tests were performed using a Micromeritics ASAP 2020 physical adsorption instrument. Samples were subjected to high vacuum treatment at 363 K and 573 K for 1 h and 3 h, respectively, followed by adsorption at a constant temperature of 77 K using N2 as the adsorbate. 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 (the physical adsorption characterization results of the molecular sieve obtained in Example A1 are shown in the figure). Figure 3 As shown, the adsorption hysteresis loop results indicate that the material contains abundant microporous structures, satisfying the characteristics of titanium-silicon molecular sieves. The micropore size is concentrated at 0.55 nm, which meets the characteristic micropore size of the double ten-membered ring cross-channel structure of titanium-silicon molecular sieves. The physical adsorption characterization results of the molecular sieves in each embodiment are consistent with... Figure 3 Similarly, this indicates that the obtained molecular sieves are all TS-1 titanium-silicon molecular sieves;

[0106] The method for testing the crystallinity of gold-loaded titanium-silicon 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°. The TS-1 sample (M196697 grade) 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 the characteristic diffraction peaks at 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.

[0107] The methods for testing the average particle size of gold-loaded titanium-silicon molecular sieves are as follows: The microstructure of the molecular sieve in the sample is observed using transmission electron microscopy, and the diameter is measured according to a scale bar. The corresponding particle size distribution is calculated by taking the average of several samples using mathematical statistical methods. The transmission electron microscopy characterization results of the molecular sieve obtained in Example A1 are as follows: Figure 2 As shown, the infrared spectral characterization results of the molecular sieves in each embodiment are compared with... Figure 2 kind.

[0108] The stretching vibration characteristic peaks of the Si-O-Ti framework structure of the titanium-silicon molecular sieve were measured using a Bruker INVENIO R and Tensor 27 infrared spectrometer with KBr as the background matrix material and after pressing the doped titanium-silicon molecular sieve into a pellet. (The infrared spectral characterization results of the molecular sieve obtained in Example A1 are shown in the figure.) Figure 4 As shown, 982cm -1 and 1263cm -1 The wavenumber characteristic peaks satisfy the stretching vibrations of the Si-O-Ti framework structure, exhibiting framework characteristics of titanium-silicon molecular sieves. The infrared spectral characterization results of the molecular sieves in each embodiment are consistent with... Figure 4 Similarly, this indicates that the obtained molecular sieves are all TS-1 titanium-silicon molecular sieves.

[0109] The Ti element chemical environment of the titanium-silicon molecular sieve was measured using an Agilent Cary 5000UV-Vis-NIR spectrometer to determine whether it has a four-coordinate framework titanium structure and whether it is loaded with Au nanoparticles (the UV spectral characterization results of the molecular sieve obtained in Example A1 are shown in the figure). Figure 5 As shown, the characteristic peak at a wavelength of 235 nm satisfies the requirements of framework titanium Ti. 4+ The four-coordinate characteristic structure exhibits a titanium-silicon molecular sieve framework structure; the characteristic peak at 543 nm wavelength represents the loading of Au nanoparticles, exhibiting an Au-like characteristic structure. The UV spectral characterization results of the molecular sieves in each embodiment are consistent with... Figure 5 Similarly, this indicates that the obtained molecular sieves are all TS-1 titanium-silicon molecular sieves loaded with gold.

[0110] The thickness of the gold-loaded titanium-silicon molecular sieve was determined by scanning electron microscopy (SEM) and measured using a scale corresponding to the magnification. Figure 1 The image shows scanning electron microscope (SEM) images of the composite palladium-based alloy material before and after the gold-loaded titanium-silicon molecular sieve was attached.

[0111] The method for testing Au loading is based on the concentration and volume of the impregnation solution, while the Au loading obtained by impregnation is corroborated by the characterization results of inductively coupled plasma optical emission spectroscopy (ICP-OES).

[0112] The method for measuring the particle size of Au is to observe it using a transmission electron microscope and determine the particle size of gold nanoparticles by measuring it according to the corresponding scale based on the magnification.

[0113] (III) Overall testing of composite membranes

[0114] 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 o exp(-E act / RT), calculated through measurement, where J H2 It is the hydrogen permeation diffusion rate, J H2 o R is the hydrogen permeation diffusion coefficient, T 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.

[0115] J H2 (Hydrogen permeation diffusion 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 (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 ).

[0116] 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 ).

[0117] 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).

[0118] Table 2

[0119]

[0120] Table 2 (continued)

[0121]

[0122]

[0123] (IV) Performance Testing

[0124] The performance of the composite membranes prepared in the above embodiments and comparative examples was tested in the preparation of propylene oxide.

[0125] like Figure 7 As shown, the composite membrane prepared above was encapsulated in a tubular reactor. First, nitrogen gas was introduced into the inner and outer sides of the composite membrane at flow rates of 10 mL / min and 30 mL / min, respectively. The temperature was then increased to 473 K at a rate of 1 K / min to activate the composite membrane for 2 hours. Afterwards, propylene and O2 were introduced from the inner side of the composite membrane (the side closer to molecular sieve 2, P). 内侧 =0.1MPa) is introduced into the reactor to release H2(P) 外侧 An epoxidation reaction was carried out in the reactor from the outside of the composite membrane (near the side of the composite palladium-based alloy material 1) at a pressure of 0.6 MPa. The reaction temperature was controlled at 473 K, and the pressure difference between the inside and outside of the composite membrane (P) was maintained at 0.6 MPa. 外侧 -P 内侧 The pressure was 0.5 MPa, with a volumetric flow rate ratio of H2:O2:C3H6:N2 of 5:5:5:35. Gases such as hydrogen, oxygen, nitrogen, carbon monoxide, carbon dioxide, and methane were analyzed using an Agilent 7890B gas chromatograph equipped with a TCD detector. Organic compounds such as propylene, propane, propionaldehyde, acrolein, acetone, acetaldehyde, and propylene oxide were analyzed using an Agilent 7890B gas chromatograph equipped with an FID detector. Propylene conversion, propylene oxide selectivity, and hydrogen utilization were calculated based on the detection results. The product was tested every 5 hours. The continuous running time was defined as the time during which the propylene conversion decreased to 90% of the initial value. The initial reaction values ​​and experimental measurements after reaching the continuous running time are shown in Table 3. The formulas for calculating propylene conversion, propylene oxide selectivity, and hydrogen utilization are as follows:

[0126] propylene conversion (C) C3H6 = (Amount of C3 product + 2 / 3 amount of C2 product + 1 / 3 amount of C1 product) / Amount of propylene in the feed gas

[0127] propylene oxide selectivity (S PO = Amount of propylene oxide in the product / (Amount of C3 product + 2 / 3 of C2 product + 1 / 3 of C1 product)

[0128] Hydrogen utilization rate (Y) H2 = Amount of propylene oxide in the product / (Amount of hydrogen in the feed gas - Amount of hydrogen in the product)

[0129] 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 (473 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.

[0130] Table 3

[0131]

[0132] 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 copper-containing composite membrane comprising a titanium-silicon molecular sieve layer, characterized in that, The composite membrane comprises a composite palladium-based alloy material and a titanium-silicon molecular sieve loaded with noble metals attached to the surface of the composite palladium-based alloy material. The composite palladium-based alloy material contains Pd and Cu, with a molar ratio of Pd to Cu of 1:(0.8-1.3). The composite palladium-based alloy material has a body-centered cubic crystal structure with a lattice parameter k of 0.2752-0.3009 nm. In the XRD pattern of the composite palladium-based alloy material, 2θ is at 35 nm. o -90 o The full width at half maximum (FWHM) of at least one characteristic peak within the range is less than or equal to 0.1602.

2. The composite membrane according to claim 1, wherein, In the XRD pattern of the composite palladium-based alloy material, 2θ is at 35°. o -90 o The full width at half maximum (FWHM) of all characteristic peaks within the range is less than or equal to 0.1602.

3. The composite membrane according to claim 1 or 2, wherein, In the XRD pattern of the composite palladium-based alloy material, or 2θ=43 o ±1 o The full width at half maximum (FWHM) of the characteristic peak at that location is less than or equal to 0.0524, or 2θ = 53. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at that location is less than or equal to 0.0698, or 2θ = 62. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at that location is less than or equal to 0.1047, or 2θ = 70°. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at that location is less than or equal to 0.1222, or 2θ = 79. o ±1 o The full width at half maximum (FWHM) of the characteristic peak at that location is less than or equal to 0.1571. And / or, the thickness of the composite palladium-based alloy material is 0.5-30µm.

4. The composite membrane according to claim 1 or 2, wherein, The thickness of the composite palladium-based alloy material is 5-15µm.

5. The composite membrane according to claim 1 or 2, wherein, The loading of precious metals in titanium-silicon molecular sieves is 0.01-10 wt%; And / or, the precious metal is selected from gold; And / or, the titanium silicate molecular sieve loaded with noble metals is at least one of TS-1, TS-2, Ti-β molecular sieve, Ti-MCM-41, Ti-MCM-48, Ti-TUD and Ti-HMS loaded with noble metals; And / or, the thickness of the titanium-silicon molecular sieve loaded with noble metals is 1-100µm; And / or, the silicon-to-titanium molar ratio of the titanium-silicon molecular sieve loaded with noble metals is (50-400):1; the average particle size is 10-300 nm; the average pore size is 0.1-100 nm; and the specific surface area is 10-700 m². 2 / g; crystallinity greater than or equal to 88%.

6. The composite membrane according to claim 1 or 2, wherein, The loading of precious metals in titanium-silicon molecular sieves is 0.01-2 wt%.

7. The composite membrane according to claim 1 or 2, wherein, The thickness of titanium-silicon molecular sieves loaded with precious metals is 5-30µm.

8. The composite membrane according to claim 1 or 2, wherein, The silicon-to-titanium molar ratio of titanium-silicon molecular sieves loaded with precious metals is (80-200):

1.

9. The composite membrane according to claim 1 or 2, wherein, The average particle size of titanium-silicon molecular sieves loaded with precious metals is 50-150 nm.

10. The composite membrane according to claim 1 or 2, wherein, The average pore size of titanium-silicon molecular sieves loaded with precious metals is 3-20 nm.

11. The composite membrane according to claim 1 or 2, wherein, The specific surface area of ​​titanium-silicon molecular sieves loaded with precious metals is 50-450 m². 2 / g.

12. The composite membrane according to claim 1 or 2, wherein, The crystallinity of titanium-silicon molecular sieves loaded with precious metals is 92-97%.

13. The composite membrane according to claim 1 or 2, wherein, 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.

14. The composite membrane according to claim 1 or 2, 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.

15. A method for preparing a composite membrane with catalytic propylene epoxidation function, characterized in that, The method includes: (1) Pd and Cu are deposited on the support, and then the support with Pd and Cu deposited is alloyed, wherein the molar ratio of Pd to Cu is 1:(0.8-1.3). The alloying treatment is performed as follows: after treatment in an activating atmosphere at a temperature of 570-600℃ and a pressure of 0.37-0.52MPa for 3-5 hours, the temperature is reduced to 100-150℃ at a rate of 70-100℃ / min. The activating atmosphere consists of gases including H2, N2, and NH3, and the volume ratio of H2, N2, and NH3 is 1:(0.2-0.5):(0.02-0.1). (2) The alloyed material is placed in a solution of a precursor containing titanium-silicon molecular sieve and subjected to hydrothermal crystallization, drying and calcination in sequence to obtain a composite membrane precursor; (3) The composite membrane precursor is impregnated with an alkaline solution containing a noble metal precursor and an organic dispersant, and then the noble metal in the noble metal precursor is converted into a reduced state in a reducing atmosphere.

16. The method according to claim 15, wherein, The total thickness of Pd and Cu deposited on the support is 0.5-30µm; And / or, the thickness of the support is 0.1-20 mm.

17. The method according to claim 15, wherein, The total thickness of Pd and Cu deposited on the support is 5-15µm.

18. The method according to claim 15, wherein, The thickness of the support is 2-5mm.

19. The method according to claim 15, wherein, The precursor solution of the titanium-containing silicon molecular sieve contains a silicon source, a titanium source, a template agent, water, and an optional surfactant.

20. The method according to claim 19, wherein, The molar ratio of the silicon source, titanium source, template agent, water and surfactant is 100:(0.25-2):(1-50):(10-3000):(0-18); And / or, relative to 1g of alloyed material, the amount of the titanium-silicon molecular sieve precursor solution used is 0.1-1.5 ml; And / or, the silicon source is at least one of silicate ester, silicate and silicon dioxide; And / or, the titanium source is at least one of titanate, titanium salt, titanium oxysulfate and titanium difluoride; And / or, the template agent is at least one selected from tetraalkylammonium hydroxide, alkylamine, and tetraalkylammonium halide; And / or, the surfactant is at least one of nonionic surfactants.

21. The method according to claim 19, wherein, The molar ratio of the silicon source, titanium source, template agent, water and surfactant is 100:(0.5-1.25):(10-30):(20-1500):(0.1-6).

22. The method according to claim 19, wherein, The silicon source is selected from at least one of tetrabutyl orthosilicate, tetraethyl orthosilicate, sodium silicate, potassium silicate, silica sol, and water glass.

23. The method according to claim 19, wherein, The titanium source is selected from at least one of tetrabutyl titanate, tetraethyl titanate, titanium tetrachloride, titanium isopropoxide, titanium sulfate, titanium oxysulfate, and titanium difluoride.

24. The method according to claim 19, wherein, The template agent is selected from at least one of tetrabutylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium hydroxide, triethylamine, hexadecyltrimethylammonium bromide, and isopropylamine.

25. The method according to claim 19, wherein, The surfactant is selected from at least one of Tween-20, Tween-21, Tween-40, Tween-60, Tween-80, Tween-85, polyethylene glycol, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ester, polyoxyethylene alkylamine, polyoxyethylene alkylamide, and polyethers.

26. The method according to claim 15, wherein, The hydrothermal crystallization method involves aging followed by crystallization. The aging conditions include an aging temperature of 60-90℃ and an aging time of 3-6 hours. The crystallization conditions include a crystallization temperature of 150-180℃ and a crystallization time of 36-72 hours. And / or, the drying conditions include: drying temperature 30-80℃, drying time 8-18h; And / or, the calcination conditions include: calcination temperature of 500-650℃ and calcination time of 3-6h.

27. The method according to claim 15, wherein, The content of the precious metal precursor, calculated as gold element, in the alkaline solution containing the precious metal precursor and the organic dispersant is 0.001-3 mol / L; And / or, the noble metal precursor is selected from at least one of chloroauric acid, gold hydroxide colloid and EDTA-Au complex; And / or, the content of organic dispersant in the alkaline solution containing the noble metal precursor and the organic dispersant is 0.01-1% by volume; And / or, the organic dispersant is selected from at least one of ethylene glycol, ethylenediamine, urea, bipyridine, and glycerol; And / or, the pH value of the alkaline solution containing the noble metal precursor and the organic dispersant is greater than or equal to 5; And / or, relative to 1g of alloyed material, the amount of alkaline solution containing noble metal precursor and organic dispersant is 0.1-1.5 ml; And / or, the impregnation conditions include: temperature 0-85℃, pH 5.2-10.3, and impregnation time 8-30h.

28. The composite membrane prepared by the method according to any one of claims 15-27.

29. A composite palladium-based alloy material, characterized in that, The composite palladium-based alloy material is the composite palladium-based alloy material as defined in any one of claims 1-14 or the product of the alloying treatment described in any one of claims 15-27.

30. The use of the composite membrane according to any one of claims 1-14 or 28 in the preparation of propylene oxide.

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