Preparation method of perovskite hydrogen permeation membrane for inhibiting element loss at high temperature

Abstract

The application relates to the field of membranes and membrane separation technology, in particular to a preparation method of a perovskite hydrogen-permeable membrane for inhibiting element loss at high temperature. The method comprises the following steps: firstly, preparing precursor powder by using an EDTA-citric acid method; then, baking the precursor powder at high temperature to obtain perovskite powder; finally, pressing the perovskite powder into a sheet type membrane embryo, and preparing a dense and defect-free perovskite hydrogen-permeable membrane by using an element infiltration sintering strategy. By creating an ion-rich environment, the method reduces the exchange between internal elements and the environment under high-temperature sintering, and inhibits the element loss of the perovskite hydrogen-permeable membrane at high temperature.

Description

Technical Field

[0001] This invention relates to the field of membranes and membrane separation, specifically to a method for preparing a perovskite hydrogen permeable membrane that suppresses elemental loss at high temperatures. Background Technology

[0002] Hybrid proton-electron conductor perovskite hydrogen permeable membranes are a type of dense, defect-free inorganic ceramic membrane. Under high-temperature conditions, hydrogen combines with lattice oxygen. At the high hydrogen partial pressure end, hydrogen diffuses to the membrane surface and is adsorbed, subsequently dissociating into protons and electrons. Protons hop between different lattice oxygen phases within the membrane, while electrons travel along the electron-conducting phase. At the low hydrogen partial pressure end, protons and electrons recombine to form hydrogen at the membrane surface. Finally, the hydrogen desorbs on the membrane surface and is carried away by the purge gas, completing the hydrogen permeation process. This type of membrane can achieve hydrogen separation without external circuitry and theoretically has 100% selectivity for hydrogen. Compared to palladium membranes, perovskite hydrogen permeable membranes exhibit high stability and lower material cost. These membranes operate at temperatures >750℃ and can be efficiently coupled with fuel cells and membrane reactors, making them a promising industrial membrane material.

[0003] Perovskite-type hydrogen permeable membranes are generally prepared through prolonged high-temperature sintering (>1200℃). However, under the harsh sintering environment of ultra-high temperatures (>1400℃), the cation and anion sites in the membrane preform vaporize and escape into the environment. This element loss significantly impairs the overall proton conductivity of the membrane. Currently, there is no effective solution to this problem caused by the harsh high-temperature sintering environment. Therefore, if the element loss caused by the aforementioned harsh high-temperature environment can be effectively suppressed, the performance of perovskite-type hydrogen permeable membranes will be further improved and developed. Summary of the Invention

[0004] The technical problem this invention aims to solve is how to effectively suppress elemental loss caused by the harsh high-temperature sintering environment during the preparation of perovskite hydrogen permeable membranes, thereby improving the overall proton conductivity and hydrogen permeability of the membrane. This invention uses powder prepared in the same batch to perform surface elemental permeation treatment on the sheet-like membrane preform, thereby creating an ion-rich environment and reducing the exchange of its internal elements with the environment during high-temperature sintering, thus preparing a dense, defect-free perovskite hydrogen permeable membrane with minimal elemental loss.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a perovskite hydrogen permeable membrane that suppresses elemental loss at high temperatures, comprising the following steps:

[0006] S1: Precursor powder was prepared using citric acid and EDTA as complexing agents according to the sol-gel method;

[0007] S2: The precursor powder is sintered, pressed into tablets, and then sintered again to obtain a dense and defect-free perovskite hydrogen permeable membrane.

[0008] Before the re-sintering, the preform obtained by pressing the tablet needs to be brought into interfacial contact with the powder obtained by sintering the precursor powder.

[0009] Preferably, the preparation method specifically includes the following steps:

[0010] 1): According to the molar ratio in the general chemical formula of perovskite hydrogen permeable membrane, weigh out nitrate powder and dissolve it in deionized water to obtain a clear solution; calculate and weigh out the clear solution and citric acid according to the molar ratio and add them to EDTA solution, add ammonia water to adjust to obtain gel, dry, grind and sieve to obtain precursor powder;

[0011] 2): After sintering, grinding and sieving the precursor powder, perovskite phase powder is obtained. Polyvinyl alcohol is then added and the powder is further ground and pressed to obtain sheet-like film preforms.

[0012] 3): The sheet-like membrane preform is placed in two layers of the perovskite phase powder and sintered to obtain a dense and defect-free perovskite hydrogen permeable membrane.

[0013] Preferably, in step 1), the perovskite hydrogen permeable membrane has the general chemical formula BaZr. 0.7 Ce 0.2 Y 0.1 O 3-δ The nitrates are Ba(NO3)2, Zr(NO3)4·5H2O, Ce(NO3)3·6H2O, Y(NO3)3·6H2O, and Co(NO3)2·6H2O. The molar ratio of total metal ions, citric acid, and EDTA in the clarified solution is 1:1 to 3:1. The gel needs to be heated for 3-5 hours before drying to evaporate the water. The drying temperature is 180-220℃ and the time is 8-10 hours. The sieving refers to passing the gel through a 300-mesh sieve.

[0014] Preferably, in step 2), the sintering temperature is 800-1000℃, the time is 4-6h, the heating rate is 2-5℃ / min, the die diameter for pressing is 14-18mm, the pressure during pressing is 12-15MPa, and the pressing time is 1-2min.

[0015] Preferably, in step 3), the sintering temperature is 1300-1500℃, the time is 9-12h, and the heating and cooling rate is 1-3℃ / min.

[0016] Hydrogen-permeable membranes prepared by any of the methods described above.

[0017] The application of the hydrogen permeable membrane in hydrogen separation under high temperature conditions.

[0018] Preferably, the preparation method is suitable for BaZrO 3-δ Hydrogen permeable membrane based on perovskite.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention uses powder prepared in the same batch to perform element permeation treatment on sheet membrane preforms to create an ion-rich environment, reducing the exchange of its internal elements with the environment during high-temperature sintering, thereby preparing a dense, defect-free perovskite hydrogen permeable membrane with minimal loss. Attached Figure Description

[0021] Figure 1 The basic mechanism for suppressing elemental loss according to an embodiment of the present invention is shown;

[0022] Figure 2 The phase formation of BZCY and BZCY-F perovskite powders after sintering at 900℃;

[0023] Figure 3 This is a flowchart of the sheet membrane pressing process;

[0024] Figure 4 SEM images of the surface microstructure of BZCY perovskite hydrogen permeable membrane and BZCY-F perovskite hydrogen permeable membrane (the upper left image is sintered BZCY without element infiltration treatment, the upper right image is sintered BZCY without element infiltration treatment, the lower left image is sintered BZCY-F with element infiltration treatment, and the lower right image is sintered BZCY-F with element infiltration treatment).

[0025] Figure 5 A comparison of hydrogen flux before and after elemental permeation treatment of BZCY and BZCY-F perovskite hydrogen permeation membranes. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1:

[0028] BaZr was prepared by element infiltration sintering process. 0.7 Ce 0.2 Y 0.1 O 3-δ (BZCY) Perovskite sheet hydrogen permeable membrane;

[0029] (1) Preparation of BZCY perovskite powder precursor: Calculate the required mass of each raw material according to the molar ratio in the general chemical formula. Add the weighed Ba(NO3)2, Zr(NO3)4·5H2O, Ce(NO3)3·6H2O, Y(NO3)3·6H2O, and Co(NO3)2·6H2O nitrate powders sequentially to a beaker. Add deionized water and stir to dissolve for about 20 minutes until the solution becomes clear. Then, according to the clear solution… The total metal ions, citric acid, and EDTA were in a molar ratio of 1:2:1. The complexing agent EDTA and citric acid were weighed and added to beakers, and deionized water was added and stirred to dissolve them. The clear solution and citric acid were added to the EDTA solution in sequence. Ammonia was added to adjust the solution to obtain a gel. The gel was heated until the water evaporated (about 4 hours). A layer of aluminum foil was covered with a beaker (with holes punched), and the beaker was placed in an oven and dried at 200°C for 9 hours to obtain a fluffy sponge-like solid. The solid was ground through a 300-mesh sieve to obtain the precursor powder.

[0030] (2) Preparation of BZCY perovskite powder: The precursor powder was weighed into an alumina crucible and calcined in a muffle furnace. The heating program was set to 900℃ for 5h and the heating rate was 2℃ / min. The powder obtained by calcination was ground through a 300-mesh sieve to obtain BZCY perovskite powder. The perovskite powder was placed in a mortar and polyvinyl alcohol was added. The powder was ground until there were no large agglomerates and the particles were fine and dispersed. The powder was weighed from the mortar and placed into a mold with a pore size (diameter) of 16mm. After pressing under a pressure of 13MPa for 1min, a sheet-like preform was obtained.

[0031] (3) A layer of BZCY perovskite powder is placed in the crucible, a sheet membrane preform prepared in step (2) is taken out and placed in the crucible, another layer of BZCY perovskite powder is placed in it, and then it is placed in a muffle furnace and sintered at 1400℃ for 10h. The heating and cooling rate is kept at 2℃ / min to prepare a dense and defect-free perovskite hydrogen permeable membrane.

[0032] Example 2:

[0033] BaZr was prepared by solid-state element infiltration sintering process. 0.7 Ce 0.2 Y 0.1 O 3-δ -F 0.05 (BZCY-F) Perovskite sheet hydrogen permeable membrane;

[0034] (1) Preparation of BZCY-F perovskite powder precursor: Based on the molar ratio in the general chemical formula, the required mass of each raw material was calculated. The weighed Ba(NO3)2, Zr(NO3)4·5H2O, Ce(NO3)3·6H2O, Y(NO3)3·6H2O, Co(NO3)2·6H2O nitrate powder and BaF2 powder were added to a beaker in sequence. In this example, BaF2 is the fluorine source in the prepared material. Its solubility in 100g of water is 0.161g (25℃). It can be stored in a glass container. After adding deionized water, Stir and dissolve for about 20 minutes until the solution is clear, and obtain a clear solution. Weigh the complexing agent EDTA and citric acid into beakers according to the molar ratio of total metal ions, citric acid and EDTA in the clear solution = 1:2:1. Add deionized water and stir to dissolve. Add the clear solution and citric acid to the EDTA solution in sequence. Adjust the solution by adding ammonia water to obtain a gel. Heat until the water evaporates (about 4 hours). Cover the mouth of the beaker with a layer of aluminum foil (with holes punched) and put it in an oven. Bake at 200°C for 9 hours to obtain a fluffy sponge-like solid. Grind it through a 300-mesh sieve to obtain the precursor powder.

[0035] (2) Preparation of BZCY-F perovskite powder: The precursor powder was weighed into an alumina crucible and calcined in a muffle furnace. The heating program was set to 900℃ for 5h and the heating rate was 2℃ / min. The powder obtained by calcination was ground through a 300-mesh sieve to obtain BZCY-F perovskite powder. The perovskite powder was placed in a mortar and polyvinyl alcohol was added. The powder was ground until there were no large agglomerates and the particles were fine and dispersed. The powder was weighed from the mortar and placed into a mold with a pore size (diameter) of 16mm. After pressing under a pressure of 13MPa for 1min, a sheet-like preform was obtained.

[0036] (3) A layer of BZCY-F perovskite powder is placed in the crucible, and a sheet membrane preform prepared in step (2) is taken out and placed in the crucible. Another layer of BZCY-F perovskite powder is then placed in the crucible and placed in a muffle furnace. The membrane is sintered at 1400℃ for 10h, and the heating and cooling rates are kept at 2℃ / min to prepare a dense and defect-free perovskite hydrogen permeable membrane.

[0037] Comparative Example 1:

[0038] The difference from Example 1 is that the solid-phase element infiltration strategy is not used; instead, the tablets are directly sintered after compression.

[0039] BaZr was prepared using a conventional sintering process. 0.7 Ce 0.2 Y 0.1 O 3-δ (BZCY) Perovskite sheet hydrogen permeable membrane;

[0040] (1) Preparation of BZCY perovskite powder precursor: Calculate the required mass of each raw material according to the molar ratio in the general chemical formula. Add the weighed Ba(NO3)2, Zr(NO3)4·5H2O, Ce(NO3)3·6H2O, Y(NO3)3·6H2O, and Co(NO3)2·6H2O nitrate powders sequentially to a beaker. Add deionized water and stir to dissolve for about 20 minutes until the solution becomes clear. Then, according to the clear solution… The total metal ions, citric acid, and EDTA were in a molar ratio of 1:2:1. The complexing agent EDTA and citric acid were weighed and added to beakers, and deionized water was added and stirred to dissolve them. The clear solution and citric acid were added to the EDTA solution in sequence. Ammonia was added to adjust the solution to obtain a gel. The gel was heated until the water evaporated (about 4 hours). A layer of aluminum foil was covered with a beaker (with holes punched), and the beaker was placed in an oven and dried at 200°C for 9 hours to obtain a fluffy sponge-like solid. The solid was ground through a 300-mesh sieve to obtain the precursor powder.

[0041] (2) Preparation of BZCY perovskite powder: The precursor powder was weighed into an alumina crucible and calcined in a muffle furnace. The heating program was set as follows: 900℃ for 5h, heating rate 2℃ / min. The powder obtained by calcination was ground through a 300-mesh sieve to obtain BZCY perovskite powder. The perovskite powder was placed in a mortar and polyvinyl alcohol was added. The powder was ground until there were no large agglomerates and the particles were fine and dispersed. The powder was weighed from the mortar and placed into a mold with a pore size (diameter) of 16mm. After pressing under a pressure of 13MPa for 1min, a sheet membrane preform was obtained. Then it was placed in a muffle furnace and sintered at 1400℃ for 10h. The heating and cooling rate was kept at 2℃ / min to prepare a perovskite hydrogen permeable membrane.

[0042] Comparative Example 2:

[0043] The difference from Example 2 is that the solid-phase element infiltration strategy is not used; instead, the tablets are directly sintered after compression.

[0044] BaZr was prepared using a conventional sintering process. 0.7 Ce 0.2 Y 0.1 O 3-δ -F 0.05 (BZCY-F) Perovskite sheet hydrogen permeable membrane;

[0045] (1) Preparation of BZCY-F perovskite powder precursor: Based on the molar ratio in the general chemical formula, calculate the required mass of each raw material. Add the weighed Ba(NO3)2, Zr(NO3)4·5H2O, Ce(NO3)3·6H2O, Y(NO3)3·6H2O, Co(NO3)2·6H2O nitrate powder, and BaF2 powder sequentially to a beaker. After adding deionized water, stir and dissolve for about 20 minutes until the solution becomes clear, obtaining a clear solution. According to... The molar ratio of total metal ions, citric acid, and EDTA in the clear solution is 1:2:1. Weigh the complexing agent EDTA and citric acid and add them to beakers separately. Add deionized water and stir to dissolve. Add the clear solution and citric acid to the EDTA solution in sequence. Adjust the solution by adding ammonia to obtain a gel. Heat until the water evaporates (about 4 hours). Cover the mouth of the beaker with a layer of aluminum foil (with holes punched) and place it in an oven. Bake at 200°C for 9 hours to obtain a fluffy sponge-like solid. Grind it through a 300-mesh sieve to obtain the precursor powder.

[0046] (2) Preparation of BZCY-F perovskite powder: The precursor powder was weighed into an alumina crucible and calcined in a muffle furnace. The heating program was set as follows: 900℃ for 5h, heating rate 2℃ / min. The powder obtained by calcination was ground through a 300-mesh sieve to obtain BZCY-F perovskite powder. The perovskite powder was placed in a mortar and polyvinyl alcohol was added. The powder was ground until there were no large agglomerates and the particles were fine and dispersed. The powder was weighed from the mortar and placed into a mold with a pore size (diameter) of 16mm. After pressing under a pressure of 13MPa for 1min, a sheet membrane preform was obtained. Then it was placed in a muffle furnace and sintered at 1400℃ for 10h. The heating and cooling rates were kept at 2℃ / min to prepare a perovskite hydrogen permeable membrane.

[0047] Morphology and performance testing:

[0048] (1) The BZCY powder from Example 1 and the BZCY-F perovskite powder from Example 2 were subjected to X-ray diffraction tests, and the results are as follows: Figure 2 As shown, BZCY and BZCY-F have been fully phased after sintering at 900℃.

[0049] (2) Scanning electron microscopy was performed on the perovskite hydrogen permeable membranes prepared in Examples 1-2 and Comparative Examples 1-2. The results are as follows: Figure 4 As shown in the figure, the membrane surface is dense and defect-free. Further analysis of its particle size distribution yields the results shown in Table 1.

[0050] Table 1 Average Particle Size

[0051] Sample Name Average particle size (μm) Example 1 Unformed grains Example 2 3.55 Comparative Example 1 0.30 Comparative Example 2 0.31

[0052] As can be seen from Table 1, the average particle size of the perovskite hydrogen permeable membrane decreased significantly after the element infiltration sintering process, indicating that the element infiltration sintering process is beneficial to the fine crystallization of this type of polycrystalline material.

[0053] (3) X-ray energy dispersive spectroscopy (EDS) was used to test the perovskite hydrogen permeable membranes prepared in Example 1 and Comparative Example 1. The elemental content results are shown in Table 2. It can be seen that the Ba element content on the surface of the perovskite hydrogen permeable membrane without elemental infiltration sintering is lower than the detection limit of the instrument, while the Ba element on the surface of the perovskite hydrogen permeable membrane with elemental infiltration sintering is almost not lost. This is because the elemental infiltration of the sheet membrane preform with powder prepared in the same batch creates an ion-rich environment, reduces the exchange of internal elements with the environment under high-temperature sintering, and inhibits the high-temperature elemental loss of the perovskite hydrogen permeable membrane.

[0054] Table 2 Elemental content determined by X-ray energy dispersive spectroscopy

[0055] element Ba Zr Ce Y O Co Example 1 (mass fraction) - 5.32％ 43.09％ 33.41％ 18.18％ - Comparative Example 1 (mass fraction) 34.43％ 18.75％ 16.61％ 11.80％ 18.08％ 0.33％

[0056] (4) The perovskite hydrogen permeable membranes prepared in Examples 1-2 and Comparative Examples 1-2 were placed on a sheet membrane hydrogen permeation device and sealed with silver paste; the device was placed in a tube furnace and heated to 900°C at a heating rate of 2°C / min, and the hydrogen flux was tested at this temperature; 50 ml / min was introduced. -1 Ar was used as the purge gas, and the exhaust gas was tested using a Nanjing Haorpu GC-9860-5C-NJ analyzer. The test results are shown in Table 3.

[0057] Table 3 Hydrogen flux test

[0058] Sample Name <![CDATA[Hydrogen flux (ml·min -1 ·cm -2 )]]> Example 1 1.1 Example 2 1.0 Comparative Example 1 0.31 Comparative Example 2 0.16

[0059] As can be seen from Table 3, the hydrogen flux of the perovskite hydrogen permeable membrane increased significantly after the element infiltration sintering process. This is because the permeate of the sheet membrane preform with powder prepared in the same batch suppressed the high-temperature element loss of the perovskite hydrogen permeable membrane and maintained the stoichiometric ratio of the material itself, thereby improving the overall hydrogen permeability of the material.

[0060] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. The application of a hydrogen-permeable membrane in hydrogen separation under high-temperature conditions, wherein the hydrogen-permeable membrane is prepared by a method for preparing a perovskite hydrogen-permeable membrane that suppresses elemental loss at high temperatures, characterized in that... The preparation method includes the following steps: 1): According to the molar ratio in the general chemical formula of perovskite hydrogen permeable membrane, weigh out nitrate powder and dissolve it in deionized water to obtain a clear solution; calculate and weigh out the clear solution and citric acid according to the molar ratio and add them to EDTA solution, add ammonia water to adjust to obtain gel, dry, grind and sieve to obtain precursor powder; 2): After sintering, grinding and sieving the precursor powder, perovskite phase powder is obtained. Polyvinyl alcohol is then added and the powder is further ground and pressed to obtain sheet-like film preforms. 3): The sheet-like membrane preform is placed in two layers of the perovskite phase powder and sintered to obtain a dense and defect-free perovskite hydrogen permeable membrane. In step 2), the sintering temperature is 800-1000℃, the time is 4-6h, the heating rate is 2-5℃ / min, the die diameter for pressing is 14-18mm, the pressure during pressing is 12-15MPa, and the pressing time is 1-2min. In step 3), the sintering temperature is 1300-1500℃, the time is 9-12h, and the heating and cooling rate is 1-3℃ / min. The general chemical formula for perovskite hydrogen permeable membranes is BaZr. 0.7 Ce 0.2 Y 0.1 O 3-δ The nitrates are Ba(NO3)2, Zr(NO3)4·5H2O, Ce(NO3)3·6H2O, and Y(NO3)3·6H2O. The molar ratio of total metal ions, citric acid, and EDTA in the clarified solution is 1:1 to 3:

1. The gel needs to be heated for 3-5 hours before drying to evaporate the water.

2. The application according to claim 1, characterized in that, Citric acid and EDTA are used as complexing agents in the sol-gel method.

3. The application according to claim 2, characterized in that, In step 1), the drying temperature is 180-220℃ and the time is 8-10h, and the sieving refers to passing through a 300-mesh sieve.

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