A Pd / (HfNb-based)C / TaZr composite membrane and its preparation method

Abstract

The application discloses a Pd / (HfNb series)C / TaZr composite film, wherein Pd is loaded in the form of nanoparticles on the surface of the (HfNb series)C / TaZr composite film, the Pd nanoparticles are 5nm-50nm, the (HfNb series)C is obtained by carbonizing a high-entropy film mixed by HfNb and one or more than two of Ti, Ta and Zr, the thickness is 0.05-0.15 microns, and the mass percentage of Zr in the TaZr is 0.5%-8%. The preparation method of the composite film comprises the following steps: 1, smelting; 2, processing TaZr foil; 3, preparing a film layer on the surface of the TaZr foil and carbonizing; 4, depositing Pd nanoparticles; and 5, annealing. By introducing the (HfNb series)C film layer on the surface of the TaZr film, the mutual diffusion at the interface of the composite film layer is inhibited, the hydrogen permeation performance of the composite film is prevented from degrading and failing, the stability of the composite film in the hydrogen permeation process is improved, and the application is suitable for the field of hydrogen purification.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen separation membrane materials and metal composite membrane technology, specifically relating to a Pd / (HfNb-based)C / TaZr composite membrane and its preparation method. Background Technology

[0002] Hydrogen, as a flexible secondary energy source, is currently mainly used in conjunction with fuel cells, which is of great significance for achieving energy conservation and emission reduction. Due to the unique physicochemical properties of hydrogen, its safety profile varies, making the use of hydrogen storage carriers a convenient and safe method for hydrogen storage and transportation in practical applications. Methanol, as a liquid, is easy to store and transport, making it a relatively ideal hydrogen storage carrier. Combining methanol steam reforming for hydrogen production with a membrane purification reactor to achieve integrated reaction-separation hydrogen production can be applied to small-scale in-situ hydrogen production scenarios.

[0003] Palladium or palladium alloy membranes are the most commonly used hydrogen separation membranes. They utilize the catalytic dissociation of hydrogen molecules by metallic palladium and the rapid permeation of interstitial hydrogen atoms within palladium at high temperatures to separate or enrich hydrogen from other impurity gases. However, the high price of metallic palladium limits its widespread industrial application.

[0004] Tantalum (Ta), niobium (Nb), vanadium (V), and other group VB refractory transition metals have hydrogen permeability coefficients that are 1-2 orders of magnitude higher than palladium at suitable temperatures. They also possess good mechanical strength, are easy to mold into various shapes, and cost only a fraction of palladium, making them promising hydrogen separation membrane materials. However, group VB metals lack catalytic dissociation activity for hydrogen molecules and their surfaces easily form dense oxide films that hinder hydrogen atom permeation, resulting in relatively low actual hydrogen permeation rates. This significantly limits their application as hydrogen permeation separation membrane materials.

[0005] The conventional solution is to plate a palladium film on the surface of the group VB metal. However, when used at high temperatures, due to interdiffusion at the interface, after a certain period of hydrogen permeation, a compound of palladium and group VB metal is formed at the interface of the composite membrane, which leads to the degradation or even failure of the hydrogen permeation performance of the composite membrane. Summary of the Invention

[0006] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a Pd / (HfNb-based)C / TaZr composite membrane. This composite membrane, by introducing an (HfNb-based)C film layer onto the surface of the TaZr membrane, effectively suppresses the interdiffusion between Pb particles and the TaZr membrane substrate at the composite membrane interface, preventing degradation and failure of the composite membrane's hydrogen permeation performance, improving the stability of the composite membrane during the hydrogen permeation process, and solving the problem of existing composite membranes' hydrogen permeation performance being affected by interfacial interdiffusion.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a Pd / (HfNb-based)C / TaZr composite film, characterized in that Pd is loaded on the surface of the (HfNb-based)C / TaZr composite film in the form of nanoparticles, wherein the size of the Pd nanoparticles is 5nm~50nm, the (HfNb-based)C is obtained by carbonization of a high-entropy film of HfNb mixed with one or more of Ti, Ta, and Zr, with a thickness of 0.05μm~0.15μm, and the mass percentage of Zr in TaZr is 0.5%~8%.

[0008] The aforementioned Pd / (HfNb-based)C / TaZr composite film is characterized in that the metal elements of HfNb in the (HfNb-based)C are in equal atomic ratio, and the (HfNb-based)C is obtained by carbonization of a high-entropy film of HfNb mixed with one or more of Ti, Ta, and Zr, wherein the metal atomic ratio of Hf to any one of Ti, Ta, and Zr is 1:4 to 4:1.

[0009] The aforementioned Pd / (HfNb-based)C / TaZr composite membrane is characterized in that the mass percentage of Zr in the TaZr is 0.5% to 3%.

[0010] Meanwhile, this invention also discloses a method for preparing the Pd / (HfNb-based)C / TaZr composite membrane as described above, characterized in that the method includes the following steps: Step 1: Mix tantalum briquettes and sponge zirconium evenly, and then melt them in an electric arc furnace to obtain TaZr alloy; Step 2: Using a rolling process, the TaZr alloy obtained in Step 1 is processed into TaZr foil, then processed to the target size, and polished until bright, ready for use; Step 3: Using magnetron sputtering, an HfNb-based film is prepared on the surface of the TaZr foil to be used in Step 2, and then carbonization is performed to form a (HfNb-based)C film to obtain a (HfNb-based)C / TaZr composite film. Step 4: Using magnetron sputtering, Pd nanoparticles are deposited on the surface of the (HfNb-based) C / TaZr composite film obtained in Step 3 to obtain a (HfNb-based) C / TaZr composite film loaded with Pd nanoparticles. Step 5: The (HfNb-based)C / TaZr composite film loaded with Pd nanoparticles obtained in Step 4 is annealed under a mixed atmosphere of argon and hydrogen to obtain the Pd / (HfNb-based)C / TaZr composite film.

[0011] The above preparation method is characterized in that the thickness of the TaZr foil in step two is 0.1 mm to 0.3 mm.

[0012] The above preparation method is characterized in that the carbonization process for forming the (HfNb-based) C film in step three is as follows: the carbonization gas is a mixture of argon and methane, and the volume percentage of methane in the mixture is 15% to 40%, the carbonization power is 150W to 300W, and the time is 30min to 50min.

[0013] The above preparation method is characterized in that the deposition time of Pd nanoparticles in step four is 10 min to 20 min.

[0014] The above preparation method is characterized in that, in step five, the argon flow rate in the argon and hydrogen mixed atmosphere is 0.15 m³ / s. 3 / h~0.4m 3 / h, the flow rate ratio of argon to hydrogen is 3:1~1:1.

[0015] The preparation method described above is characterized in that the annealing temperature in step five is 500℃±10℃.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention introduces a (HfNb-based) C film layer on the surface of the TaZr membrane, which effectively inhibits the interdiffusion between Pb particles and the TaZr membrane substrate at the interface of the composite membrane, maintains the stability of the hydrogen permeation flux of the composite membrane, avoids the degradation and failure of the hydrogen permeation performance of the composite membrane, improves the stability of the composite membrane during the hydrogen permeation process, and extends the service life of the composite membrane.

[0017] 2. This invention introduces a (HfNb-based)C film layer on the surface of the TaZr membrane. By utilizing the protective effect of the (HfNb-based)C film layer, the oxidation of the TaZr surface by oxygen is effectively inhibited, preventing the TaZr membrane substrate from being oxidized and losing its hydrogen permeation capacity during service, thereby further improving the stability of the hydrogen permeation performance of the composite membrane.

[0018] 3. The (HfNb-based) C film layer introduced on the surface of the TaZr membrane in this invention increases the adsorption capacity of hydrogen in the composite membrane and intercepts other gases, effectively reducing the gas polarization effect on the surface of the composite membrane and improving the hydrogen permeation stability of the composite membrane. 4. The composite membrane preparation process of the present invention is simple, short, easy to operate, environmentally friendly, low in cost, and suitable for large-scale production. Furthermore, the composite membrane can be used as a metal membrane in the field of hydrogen purification.

[0019] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0020] Example 1 In this embodiment, Pd is loaded onto the surface of the (TaHfNbZr)C / TaZr composite film in the form of nanoparticles. The size of the Pd nanoparticles is 5nm~30nm. (TaHfNbZr)C is obtained by carbonization of a high-entropy film of HfNb mixed with Ta and Zr, with a thickness of 0.05μm. The metal elements of HfNb are in an equiatomic ratio, and the metal elements of Ta and Zr are in an equiatomic ratio, with the metal atom ratio of Hf to Ta being 1:4. The mass percentage of Zr in TaZr is 1%.

[0021] The preparation method of the Pd / (TaHfNbZr)C / TaZr composite membrane in this embodiment includes the following steps: Step 1: Mix tantalum briquettes and sponge zirconium evenly, and then melt them in an electric arc furnace to obtain TaZr alloy; Step 2: Using a rolling process, the TaZr alloy obtained in Step 1 is processed into TaZr foil with a thickness of 0.3mm, then processed to the target size and polished to a bright finish for later use. Step 3: Using magnetron sputtering, a TaHfNbZr film is prepared on the surface of the TaZr foil to be used in Step 2, and then carbonization is performed to form a (TaHfNbZr)C film, resulting in a (TaHfNbZr)C / TaZr composite film; the carbonization process for forming the (TaHfNbZr)C film is as follows: the carbonization gas is a mixture of argon and methane, and the volume percentage of methane in the mixture is 15%, the carbonization power is 300W, and the time is 30min; Step 4: Using magnetron sputtering, Pd nanoparticles are deposited on the surface of the (TaHfNbZr)C / TaZr composite film obtained in Step 3. The deposition time is 10 min, thus obtaining the (TaHfNbZr)C / TaZr composite film loaded with Pd nanoparticles. Step 5: The (TaHfNbZr)C / TaZr composite film loaded with Pd nanoparticles obtained in Step 4 is annealed under a mixed atmosphere of argon and hydrogen, with an argon flow rate of 0.15 m³ / h. 3 The flow rate of argon to hydrogen was 3:1, and the annealing temperature was 500℃±10℃, resulting in a Pd / (TaHfNbZr)C / TaZr composite membrane.

[0022] Example 2 In this embodiment, Pd is loaded onto the surface of the (TiHfNbZr)C / TaZr composite film in the form of nanoparticles. The size of the Pd nanoparticles is 15nm~50nm. (TiHfNbZr)C is obtained by carbonization of a high-entropy film of HfNb mixed with Ti and Zr, with a thickness of 0.15μm. The metal elements of HfNb are in an equiatomic ratio, Ti and Zr are in an equiatomic ratio, and the metal atom ratio of Hf to Zr is 1:4. The mass percentage of Zr in TaZr is 3%.

[0023] The preparation method of the Pd / (TiHfNbZr)C / TaZr composite film in this embodiment includes the following steps: Step 1: Mix tantalum briquettes and sponge zirconium evenly, and then melt them in an electric arc furnace to obtain TaZr alloy; Step 2: Using a rolling process, the TaZr alloy obtained in Step 1 is processed into TaZr foil with a thickness of 1.0 mm, then processed to the target size and polished until bright, ready for use; Step 3: Using magnetron sputtering, a TiHfNbZr film is prepared on the surface of the TaZr foil to be used in Step 2, and then carbonization is performed to form a (TiHfNbZr)C film, resulting in a (TiHfNbZr)C / TaZr composite film. The carbonization process for forming the (TiHfNbZr)C film is as follows: the carbonization gas is a mixture of argon and methane, and the volume percentage of methane in the mixture is 40%, the carbonization power is 150W, and the time is 50min. Step 4: Using magnetron sputtering, Pd nanoparticles are deposited on the surface of the (TiHfNbZr)C / TaZr composite film obtained in Step 3. The deposition time is 20 min, thus obtaining the TiHfNbZr)C / TaZr composite film loaded with Pd nanoparticles. Step 5: The (TiHfNbZr)C / TaZr composite film loaded with Pd nanoparticles obtained in Step 4 is annealed under a mixed atmosphere of argon and hydrogen, with an argon flow rate of 0.4 m³ / s. 3 The flow rate of argon to hydrogen was 1:1, and the annealing temperature was 500℃±10℃, resulting in a Pd / (TiHfNbZr)C / TaZr composite membrane.

[0024] Example 3 In this embodiment, Pd is loaded onto the surface of the (HfNbZr)C / TaZr composite film in the form of nanoparticles. The size of the Pd nanoparticles is 25nm~50nm. The (HfNbZr)C is obtained by carbonization of a high-entropy film of HfNb and Zr, with a thickness of 0.1μm. The metal elements of HfNb are in equal atomic ratio, and the metal atomic ratio of Hf to Zr is 4:1. The mass percentage of Zr in TaZr is 8%.

[0025] The preparation method of the Pd / (HfNbZr)C / TaZr composite membrane in this embodiment includes the following steps: Step 1: Mix tantalum briquettes and sponge zirconium evenly, and then melt them in an electric arc furnace to obtain TaZr alloy; Step 2: Using a rolling process, the TaZr alloy obtained in Step 1 is processed into TaZr foil with a thickness of 0.6mm, then processed to the target size and polished until bright, ready for use; Step 3: Using magnetron sputtering, an HfNbZr film is prepared on the surface of the TaZr foil to be used in Step 2, and then carbonization is performed to form a (HfNbZr)C film, resulting in a (HfNbZr)C / TaZr composite film. The carbonization process for forming the (HfNbZr)C film is as follows: the carbonization gas is a mixture of argon and methane, and the volume percentage of methane in the mixture is 30%, the carbonization power is 260W, and the time is 40min. Step 4: Using magnetron sputtering, Pd nanoparticles are deposited on the surface of the (HfNbZr)C / TaZr composite film obtained in Step 3. The deposition time is 15 min, thus obtaining the (HfNbZr)C / TaZr composite film loaded with Pd nanoparticles. Step 5: The (HfNbZr)C / TaZr composite film loaded with Pd nanoparticles obtained in Step 4 is annealed under a mixed atmosphere of argon and hydrogen, with an argon flow rate of 0.3 m³ / h. 3 The flow rate of argon to hydrogen was 2:1, and the annealing temperature was 500℃±10℃, resulting in a Pd / (HfNbZr)C / TaZr composite membrane.

[0026] Example 4 In this embodiment, Pd is loaded onto the surface of the (HfNbTiTaZr)C / TaZr composite film in the form of nanoparticles. The size of the Pd nanoparticles is 25nm~50nm. (HfNbTiTaZr)C is obtained by carbonization of a high-entropy film of HfNb mixed with Ti, Ta and Zr, with a thickness of 0.1μm. The metal elements of HfNb are in an equiatomic ratio, and Ti, Ta and Zr are in an equiatomic ratio. The metal atom ratio of Hf to Ta is 1:1. The mass percentage of Zr in TaZr is 0.5%.

[0027] The preparation method of the Pd / (HfNbTiTaZr)C / TaZr composite film in this embodiment includes the following steps: Step 1: Mix tantalum briquettes and sponge zirconium evenly, and then melt them in an electric arc furnace to obtain TaZr alloy; Step 2: Using a rolling process, the TaZr alloy obtained in Step 1 is processed into TaZr foil with a thickness of 0.6mm, then processed to the target size and polished until bright, ready for use; Step 3: Using magnetron sputtering, prepare an equiatomic HfNbTiTaZr film on the surface of the TaZr foil to be used in Step 2, and then perform carbonization to form a (HfNbTiTaZr)C film to obtain a (HfNbTiTaZr)C / TaZr composite film; the carbonization process for forming the (HfNbTiTaZr)C film is as follows: the carbonization gas is a mixture of argon and methane, and the volume ratio of methane in the mixture is 30%, the carbonization power is 260W, and the time is 40min; Step 4: Using magnetron sputtering, Pd nanoparticles are deposited on the surface of the (HfNbTiTaZr)C / TaZr composite film obtained in Step 3. The deposition time is 15 min, thus obtaining the (HfNbTiTaZr)C / TaZr composite film loaded with Pd nanoparticles. Step 5: The (HfNbTiTaZr)C / TaZr composite film loaded with Pd nanoparticles obtained in Step 4 is annealed under a mixed atmosphere of argon and hydrogen, with an argon flow rate of 0.3 m³ / h. 3 The flow rate of argon to hydrogen was 2:1, and the annealing temperature was 500℃±10℃, resulting in a Pd / (HfNbTiTaZr)C / TaZr composite membrane.

[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A Pd / (HfNb-based)C / TaZr composite membrane, characterized in that, Pd is loaded in the form of nanoparticles on the surface of a (HfNb-based)C / TaZr composite film. The size of the Pd nanoparticles is 5 nm to 50 nm. The (HfNb-based)C is obtained by carbonization of a high-entropy film of HfNb mixed with one or more of Ti, Ta, and Zr, with a thickness of 0.05 μm to 0.15 μm. The mass percentage of Zr in TaZr is 0.5% to 8%.

2. The Pd / (HfNb-based)C / TaZr composite membrane according to claim 1, characterized in that, The HfNb metal element in the (HfNb system)C is in an equal atomic ratio, and the (HfNb system)C is obtained by carbonization of a high-entropy film of HfNb mixed with one or more of Ti, Ta, and Zr, wherein the metal atom ratio of Hf to any one of Ti, Ta, and Zr is 1:4 to 4:

1.

3. The Pd / (HfNb-based)C / TaZr composite membrane according to claim 1, characterized in that, The Zr content in the TaZr is 0.5% to 3% by mass.

4. A method for preparing a Pd / (HfNb-based)C / TaZr composite membrane as described in any one of claims 1 to 3, characterized in that, The method includes the following steps: Step 1: Mix tantalum briquettes and sponge zirconium evenly, and then melt them in an electric arc furnace to obtain TaZr alloy; Step 2: Using a rolling process, the TaZr alloy obtained in Step 1 is processed into TaZr foil, then processed to the target size, and polished until bright, ready for use; Step 3: Using magnetron sputtering, an HfNb-based film is prepared on the surface of the TaZr foil to be used in step 2, and then carbonization is performed to form a (HfNb-based)C film to obtain a (HfNb-based)C / TaZr composite film. Step 4: Using magnetron sputtering, Pd nanoparticles are deposited on the surface of the (HfNb-based) C / TaZr composite film obtained in Step 3 to obtain a (HfNb-based) C / TaZr composite film loaded with Pd nanoparticles. Step 5: The (HfNb-based)C / TaZr composite film loaded with Pd nanoparticles obtained in Step 4 is annealed under a mixed atmosphere of argon and hydrogen to obtain the Pd / (HfNb-based)C / TaZr composite film.

5. The preparation method according to claim 4, characterized in that, The thickness of the TaZr foil mentioned in step two is 0.1 mm to 0.3 mm.

6. The preparation method according to claim 4, characterized in that, The process for forming the (HfNb-based) C film by carbonization in step three is as follows: the carbonization gas is a mixture of argon and methane, and the volume percentage of methane in the mixture is 15% to 40%, the carbonization power is 150W to 300W, and the time is 30min to 50min.

7. The preparation method according to claim 4, characterized in that, The deposition time for Pd nanoparticles in step four is 10 min to 20 min.

8. The preparation method according to claim 4, characterized in that, In step five, the argon flow rate in the argon and hydrogen mixed atmosphere is 0.15 m³ / s. 3 / h~0.4m 3 / h, the flow ratio of argon to hydrogen is 3:1 to 1:

1.

9. The preparation method according to claim 4, characterized in that, The annealing temperature in step five is 500℃±10℃.