Method for repairing defects of palladium composite membrane, repaired palladium composite membrane and application thereof

Abstract

The present application discloses a method for repairing defects of a palladium composite membrane, the repaired palladium composite membrane and its application. In a sealed reactor, a palladium membrane module is immersed in a palladium solution containing acid radicals, and a displacement reaction occurs under an inert atmosphere to obtain the repaired palladium composite membrane; the palladium membrane module includes a palladium membrane and a support; the support includes at least one metal element among Fe, Cr, and Mn; the thickness of the palladium membrane is 0.5 - 50 μm. This method uses a palladium salt solution to perform high-pressure penetration modification on the palladium composite membrane. Under the applied pressure, the palladium salt solution is more likely to penetrate into the interior of the porous stainless steel support. At the non-dense defect sites on the surface of the palladium membrane, metal elements such as Fe, Cr, and Mn in the porous stainless steel support react with the penetrated Pd<supgt;2+< / supgt; under an acidic environment to undergo a displacement reaction. The Pd after the reaction adheres to the defect sites on the surface of the palladium membrane, thereby filling the defects of the palladium composite membrane.

Description

Technical Field

[0001] The present application relates to a method for repairing defects of a palladium composite membrane, a repaired palladium composite membrane and an application thereof, belonging to the technical fields of hydrogen purification and hydrogen energy. Background Art

[0002] Hydrogen has received extensive attention due to its high calorific value, cleanliness and greenness. Palladium composite membranes have broad application prospects in hydrogen purification, hydrogenation, dehydrogenation, oxidation and other hydrogen-related membrane reactors.

[0003] Metallic palladium membranes have excellent permeability and selectivity for hydrogen and its isotope gases. Other gases except hydrogen cannot permeate through the palladium membrane. Therefore, palladium membranes can be used for the separation and purification of hydrogen, and have the advantages of small size, compactness and high purity (the purity of hydrogen can reach more than 7 nines), and have important application prospects in ultra-pure hydrogen purification in the electronic information industry and the utilization of hydrogen sources for fuel cells, etc.

[0004] Traditional pure palladium membranes are usually more than 50 microns thick. Due to the thickness limitation, the hydrogen permeation rate and production cost are not ideal. The thickness of supported palladium membranes supported by porous stainless steel or ceramics can be reduced to a few microns, and the cost is reduced by more than 10 times, which can meet the requirements of large-scale applications. However, along with this comes the possibility of a small number of pinholes in the palladium composite membrane, which no longer has unique selectivity for hydrogen, and a small amount of other gases such as N2 and CO may permeate through, affecting the purity and quality of hydrogen. Therefore, developing appropriate defect modification technologies is the key to improving the quality of palladium membranes. Summary of the Invention

[0005] Palladium selectivity is an important index for evaluating palladium composite membranes. Defects on the membrane surface will lead to a decrease in selectivity, thus affecting the purity of separated hydrogen. The purpose of the present application is to provide a new technology for repairing defects of palladium composite membranes.

[0006] In one aspect of the present application, a method for repairing defects of a palladium composite membrane is provided, and the method includes:

[0007] In a sealed reactor, immersing a palladium membrane assembly in a palladium solution containing acid root ions, and under an inert atmosphere, a displacement reaction occurs to obtain a repaired palladium composite membrane;

[0008] The palladium membrane assembly includes a palladium membrane and a support;

[0009] The support includes at least one metal element of Fe, Cr, and Mn;

[0010] The thickness of the palladium membrane is 0.5 - 50 μm.

[0011] Optionally, the pressure of the displacement reaction is 30 - 50 bar.

[0012] Optionally, the pressure of the displacement reaction is independently selected from any value of 30 bar, 40 bar, 50 bar or the range value between any two of the above.

[0013] Optionally, the time of the displacement reaction is 30 - 120 min.

[0014] Optionally, the time of the displacement reaction is independently selected from any value of 30 min, 60 min, 90 min, 120 min or the range value between any two of the above.

[0015] Optionally, the temperature of the displacement reaction is 0 - 80 °C.

[0016] Optionally, the temperature of the displacement reaction is independently selected from any value of 0 °C, 20 °C, 40 °C, 60 °C, 80 °C or the range value between any two of the above.

[0017] Optionally, in the palladium solution, the concentration of palladium ions is 0.01 mol / L - 1 mol / L.

[0018] Optionally, in the palladium solution, the concentration of palladium ions is 0.1 - 1 mol / .

[0019] Optionally, in the palladium solution, the concentration of palladium ions is independently selected from any value of 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.8 mol / L, 1 mol / L or the range value between any two of the above.

[0020] Optionally, the inert atmosphere is selected from at least one of nitrogen, argon, and helium.

[0021] Optionally, the acid radical ions are selected from at least one of chloride ions, nitrate ions, and carbonate ions.

[0022] As a specific embodiment, the method for repairing the defects of the palladium composite membrane includes:

[0023] Take a certain amount of palladium chloride solution and add it to a customized long-tube glass. Place the metal palladium membrane tube in the solution, and place the whole in a high-pressure device. Pressurize to 30 - 50 bar under a nitrogen atmosphere and keep it for 30 min. Then wash the metal palladium membrane tube clean with deionized water. The concentration of the palladium chloride solution is 0.01 mol / L - 1 mol / L, preferably 0.1 mol / L.

[0024] The key point of this method for repairing the defects of the palladium composite membrane lies in repairing the defects of the metal palladium composite membrane with a palladium chloride solution through a displacement reaction. Under a nitrogen atmosphere, the palladium chloride solution penetrates into the interior of the porous stainless steel support. Inside the porous stainless steel support, metal elements such as Fe, Cr, and Mn react with the infiltrated Pd in an acidic environment. 2+ A displacement reaction occurs. The principle is: Pd 2+ + Fe = Fe 2+ + Pd. The Pd after the reaction adheres to the defect sites on the surface of the palladium membrane, thus filling the defects of the palladium composite membrane.

[0025] Another aspect of this application provides a repaired palladium composite membrane obtained by the above method for repairing the defects of the palladium composite membrane.

[0026] Another aspect of this application provides an application of the above repaired palladium composite membrane in the gas separation of a hydrogen-containing reaction gas mixture and / or the production of ultra-pure hydrogen.

[0027] The beneficial effects that this application can produce include:

[0028] This method uses a palladium chloride solution to penetrate and modify the palladium composite membrane under high pressure. Under the applied pressure, the palladium chloride solution is more likely to penetrate into the interior of the porous stainless steel support. At the non-dense defect sites on the surface of the palladium membrane, metal elements such as Fe, Cr, and Mn inside the porous stainless steel support react with the infiltrated Pd 2+ in a displacement reaction. The Pd after the reaction adheres to the defect sites on the surface of the palladium membrane, thus filling the defects of the palladium composite membrane. This modification method has simple equipment and convenient operation, and the selectivity of the palladium composite membrane is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the principle of the technology for repairing the defects of the palladium composite membrane in this application.

[0030] Figure 2 It is a schematic diagram of the operation of the palladium chloride defect repair technology in Example 1 of this application.

[0031] Figure 3 It is a schematic diagram of the operation of the palladium chloride defect repair technology in Example 2 of this application.

[0032] List of components and reference numerals:

[0033] 1. Metal palladium membrane tube, 2. Glass barrel, 3. Metal shell, 4. Nitrogen inlet, 5. Tail gas outlet, 6. Plate-shaped porous supported metal palladium membrane. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The following describes this application in detail with reference to the embodiments, but this application is not limited to these embodiments.

[0035] Unless otherwise specified, the raw materials in the embodiments of this application are all purchased through commercial channels.

[0036] The analysis methods in the embodiments of this application are as follows:

[0037] Use a flow meter for leak rate analysis.

[0038] As Figure 1 shown, according to an embodiment of this application, a method for repairing defects of a novel palladium composite membrane uses a palladium chloride solution for high-pressure penetration to modify the palladium composite membrane. Under the application of pressure, the palladium chloride solution is more likely to penetrate into the porous stainless steel support. At the defective parts where the palladium membrane surface is not dense, metal elements such as Fe, Cr, and Mn in the porous stainless steel support react with the penetrated Pd 2+ in a displacement reaction. The principle is: Pd 2+ +Fe = Fe 2+ +Pd.

[0039] The reacted Pd adheres to the defective parts on the palladium membrane surface, thus filling the defects of the palladium composite membrane. This modification method has simple equipment and convenient operation, and the selectivity of the palladium composite membrane is significantly improved. During the use of this method, the pressure of the high-pressure device is maintained at 30 Bar to 50 Bar.

[0040] When performing defect repair, place the palladium composite membrane tube in a long glass tube filled with palladium chloride solution, place the whole in a high-pressure device, seal it, and pressurize it to 30 - 50 bar under a nitrogen atmosphere for 30 minutes.

[0041] Example 1

[0042] As Figure 2 shown, the process of palladium membrane repair is as follows: During the separation process, metal membrane defects occur and the selectivity decreases. Immerse the palladium membrane tube in a glass barrel filled with palladium chloride solution. Under a nitrogen atmosphere, the palladium chloride solution penetrates into the porous stainless steel support, and a displacement reaction occurs at the defective parts on the palladium membrane surface, thus filling the palladium membrane defects.

[0043] Specifically, immerse a defective metal palladium membrane tube (the support tube material is a stainless steel porous support, and the palladium membrane thickness is 10 μm) in a glass barrel filled with 0.1 mol / L palladium chloride solution, place the whole in a closed housing, introduce nitrogen from the bottom of the housing, add the pressure to 30 Bar, and stay at 20 °C for 30 minutes. After 30 minutes, the service life and hydrogen purity of the metal palladium membrane tube are significantly improved. The nitrogen permeation rate decreases from 30 ml / min per kilogram to 0.5 ml / min.

[0044] Example 2

[0045] As Figure 3As shown, the defective plate-shaped porous supported palladium membrane (the material of the support plate is a stainless steel porous carrier, and the thickness of the palladium membrane is 5 μm) is immersed in a glass barrel filled with a 0.3 mol / L palladium chloride solution. The whole is placed in a sealed housing. Nitrogen is introduced from the bottom of the housing, and the pressure is increased to 50 Bar. At 40 °C, it stays for 30 minutes. After 30 minutes, both the service life and the hydrogen purity of the plate-shaped porous supported palladium membrane are significantly improved. The nitrogen permeation rate is reduced from 5 ml / min per kilogram to 0.01 ml / min.

[0046] As described above, these are only several embodiments of the present application and do not impose any form of limitation on the present application. Although the present application is disclosed with preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, making some changes or modifications using the technical content disclosed above is equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A method for repairing defects of a palladium composite film, characterized in that: In a sealed reactor, the palladium membrane assembly is immersed in a palladium solution containing acid radical ions, and a replacement reaction occurs under an inactive atmosphere to obtain a repaired palladium composite membrane; The palladium membrane assembly comprises a palladium membrane and a support; The support body includes at least one metal element of Fe, Cr, and Mn; The thickness of the palladium film is 0.5 to 50 μm; The acid ion is selected from at least one of chloride ion, nitrate ion and carbonate ion; The pressure of the replacement reaction is 30 to 50 bar; The temperature of the replacement reaction is 20-60°C.

2. The method according to claim 1, characterized in that The replacement reaction time is 30 to 120 minutes.

3. The method according to claim 1, characterized in that In the palladium solution, the concentration of palladium ions is 0.01 mol / L to 1 mol / L.

4. The method according to claim 1, characterized in that: In the palladium solution, the concentration of palladium ions is 0.1-1 mol / L.

5. The method according to claim 1, characterized in that: The inert atmosphere is selected from at least one of nitrogen, argon and helium.

6. A repaired palladium composite membrane obtained according to the method for repairing defects of a palladium composite membrane according to any one of claims 1 to 5.

7. Use of the repaired palladium composite membrane according to claim 6 in gas separation of hydrogen-containing reaction mixture and / or production of ultrapure hydrogen.

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