A layered perovskite-like structure ceramic oxygen permeable membrane and a preparation method thereof

Abstract

The application discloses a layered perovskite structure ceramic oxygen permeation membrane and a preparation method thereof. The powder material is prepared by adopting an ethylenediamine tetraacetic acid (EDTA)-citric acid double complexing method, and the ceramic oxygen permeation membrane is prepared by adopting an organic auxiliary extrusion molding method combined with a high-temperature sintering method. The ceramic oxygen permeation membrane is composed of a layered perovskite structure (Pr 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.25‑x Ta x )2O 7+δ (x=0.05-0.2) material modified by nano praseodymium oxide particles. The ceramic oxygen permeation membrane prepared by the application has good long-term high-temperature stability and high oxygen permeability in a CO2-containing atmosphere. The oxygen permeation membrane material can also be used as an air electrode material of a solid oxide fuel cell / electrolytic cell, and therefore has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of functional ceramic materials, and particularly relates to a layered perovskite structure ceramic oxygen permeable membrane and a preparation method thereof. BACKGROUND

[0002] The ceramic oxygen permeable membrane with dense microstructure has theoretically 100% oxygen permeation selectivity, and has wide application prospects in the membrane reactor for air separation to prepare high-purity oxygen, oxygen-enriched combustion, CO2 capture, partial oxidation of natural gas (or methane) into synthesis gas or selective oxidation of hydrocarbons, etc. Since Professor Teraoka of Japan systematically studied the oxygen permeation performance of the perovskite oxide LaCoO 3-δ Since the membrane material was systematically studied for oxygen permeation performance in the 1980s of last century, the research and development of the dense oxygen permeable membrane of the single-phase mixed conductor of the perovskite structure has attracted more and more attention. Among them, the most typical two kinds of ceramic oxygen permeable membrane materials of the perovskite structure are Ba 1-x Sr x Co 1- y Fe y O 3-δ and La 1-x Sr x Co 1-y Fe y O 3-δ However, the single-phase perovskite mixed conductor oxygen permeable membrane generally has problems of poor chemical stability and high-temperature long-term structural stability, and the membrane working environment often has a certain concentration of carbon dioxide, which on the one hand makes the membrane material easy to react with carbon dioxide to cause membrane structure damage, and on the other hand, carbon dioxide is easy to be adsorbed on the membrane surface oxygen vacancy sites and seriously affects the oxygen transport performance of the membrane, and even loses the oxygen permeation ability.

[0003] In order to solve the above problems of the single-phase perovskite structure ceramic oxygen permeable membrane, people turn to develop a two-phase mixed conductor ceramic oxygen permeable membrane, such as Zr 0.8 Y 0.2 O 2-δ (YSZ) - La 0.8 Sr 0.2 Cr 0.5 Fe 0.5 O 3-δ and Ce 0.8 Sm 0.2 O 2-δ (SDC) -La 0.8 Sr 0.2 MnO 3-δand SDC, etc. as the oxygen ion conducting phase (volume fraction ≥ 50%), and the perovskite electronic conductor or mixed conductor mainly as the electronic conducting phase. Since the content of the perovskite oxide with relatively poor stability in the film material is reduced, the high-temperature CO2 corrosion resistance of the film is enhanced, and the short-term stability is improved. However, the dual-phase film still contains a high content of the perovskite oxide phase with poor stability, and it is difficult to avoid the diffusion reaction between the two phases at high temperature, so that the long-term stability of the film cannot be effectively improved. On the other hand, the oxygen ion conductivity of materials such as YSZ and SDC is relatively low, resulting in very low oxygen permeation flux of the film, thereby causing a huge bottleneck in the application of the dual-phase film.

[0004] Therefore, the present application aims at the problems of insufficient high-temperature structural stability and poor CO2 corrosion resistance of the existing ceramic oxygen permeable film, and combines the Ruddlesden-Popper (RP) type layered perovskite structure characteristics and the catalytic properties of rare earth nanoparticles to design and prepare a layered perovskite structure ceramic oxygen permeable film with good long-term high-temperature stability and high oxygen permeation performance in a CO2-containing atmosphere. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a layered perovskite structure ceramic oxygen permeable film with excellent performance, simple process and suitable for industrial production, and a preparation method thereof.

[0006] To solve the above technical problems, the technical solution of the present application is as follows: a layered perovskite structure ceramic oxygen permeable film, characterized in that the ceramic oxygen permeable film is composed of a layered perovskite structure (Pr 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.25-x Ta x )2O 7+δ (x = 0.05-0.2) material modified by nano praseodymium oxide particles.

[0007] The preparation method of the above-mentioned layered perovskite structure ceramic oxygen permeable film, characterized by comprising the following steps:

[0008] Step one: synthesis of film material powder

[0009] First, according to the formula of the membrane material, metal ion nitrate is dissolved in a proper amount of deionized water, and then citric acid and EDTA are added according to the molar ratio of total metal ions: citric acid: EDTA = 1:1.5:1, and stirred for 2 hours to make the components fully dissolved and the metal ions fully complexed, obtaining a uniform mixed ion solution; then ammonia water is added dropwise to the mixed ion solution to adjust the pH of the solution to 7, and then the solution is placed on a heating plate to evaporate into a dark gel until it self-ignites, obtaining a ceramic membrane material precursor; finally, the precursor is calcined at 1080°C for 3 hours to obtain a fluffy ultra-fine powder material;

[0010] Step two: preparation of dense ceramic membrane

[0011] First, a certain amount of polyether sulfone is dissolved in the solvent N-methyl pyrrolidone to form a polymer solution, and then polyvinyl pyrrolidone and the powder material prepared in step one are added to prepare a uniform slurry; the prepared slurry is transferred to the slurry tank of the extrusion molding device, vacuumed for 20 minutes to exhaust, and then molded by extrusion using a mold with an internal tube; the hollow wet membrane extruded through the mold under a nitrogen pressure of 0.08 MPa is soaked in an external coagulant for 24 hours for solidification, then taken out and dried at room temperature, and then fired at 1280-1320°C for 3 hours, and finally naturally cooled to room temperature in the furnace, obtaining a hollow fiber ceramic oxygen permeation membrane.

[0012] The chemical composition formula of the ceramic oxygen permeation membrane is: (Pr 0.5+y Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.25-x Ta x )2O 7+δ , wherein x = 0.05-0.20, y = 0.05-0.15.

[0013] The chemical composition formula of the ceramic oxygen permeation membrane is: (Pr 0.5+y Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.25-x Ta x )2O 7+δ , wherein x = 0.10, y = 0.10.

[0014] The EDTA in step one needs to be pre-dissolved in dilute ammonia water.

[0015] The composition of the slurry in step two is: 55 wt% powder material, 8 wt% polyether sulfone, 36 wt% N-methyl pyrrolidone, and 1 wt% polyvinyl pyrrolidone.

[0016] The inner tube in the mold in the extrusion process in the second step is connected to water as an internal coagulant.

[0017] The external coagulant in the second step is 80 wt% ethanol solution.

[0018] The ceramic oxygen permeable membrane material can be used as an air electrode material of a solid oxide fuel cell / electrolytic cell.

[0019] Advantages of the present application:

[0020] (1) high content of Pr ions and larger size of Sr ions and small amount of Ba ions are introduced into the A site of the A3B2O7 type layered perovskite structure material, which helps to maintain a larger unit cell parameter to reduce the oxygen ion migration activation energy and improve the oxygen permeation flux while improving the CO2 corrosion resistance of the material; the high valence rare earth metal Pr ions (+3 and +4 mixed valence) at the A site and the high valence Nb and Ta ions (+5 valence) at the B site synergistically form a large amount of interlayer gap oxygen (Pr 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.25-x Ta x )2O 7+δ material, effectively obtaining an electronic-oxygen ion mixed conductor material with high oxygen ion conductivity, thereby significantly improving the oxygen permeation flux of the membrane material; the synergistic effect of Fe, Ni, Nb and Ta ions at the B site also helps the membrane material to have good CO2 corrosion resistance;

[0021] (2) when the membrane material of the present application is used for oxygen separation, the oxygen ion transmission is mainly through the gap oxygen rather than the oxygen vacancies, which can significantly reduce the adsorption of CO2 on the membrane surface, thereby eliminating the hindering effect of CO2 in the raw gas on the oxygen ion transmission of the membrane, and also helping to improve the CO2 corrosion resistance of the membrane;

[0022] (3) in the synthesis of the membrane material, by introducing an appropriate excess of Pr and using ethanol solution as the external coagulant in the extrusion molding process to control the phase transformation rate on the outer side of the membrane, a uniform distribution of nano-praseodymium oxide grains can be formed on the surface of the membrane, which can improve the adsorption of oxygen molecules on the membrane surface and their reduction activity during the oxygen separation process, thereby promoting the surface exchange and mass transfer process of oxygen and also helping to improve the oxygen separation performance of the membrane;

[0023] (4) the layered perovskite structure material provided by the present application has high oxygen reduction catalytic activity and can also be used as an air electrode material of a solid oxide fuel cell / electrolytic cell. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1SEM photograph of the surface of the hollow fiber ceramic oxygen permeable membrane prepared in Example 1. DETAILED DESCRIPTION

[0025] The application will be further described in connection with the specific embodiments.

[0026] Example 1: Pr6+ modified (Pr 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.15 Ta 0.1 )2O 7+δ ceramic oxygen permeable membrane

[0027] Step one: synthesis of membrane material powder

[0028] First, according to the formula composition (Pr 0.6 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.15 Ta 0.1 )2O 7+δ , the corresponding proportion of metal ion nitrate is weighed and dissolved in a suitable amount of deionized water, then citric acid and EDTA (EDTA is pre-dissolved in dilute ammonia water) are added according to the molar ratio of total metal ion: citric acid: EDTA = 1:1.5:1, and the mixture is continuously stirred for 2 hours to ensure that each component is fully dissolved and the metal ions are fully complexed, obtaining a uniform mixed ion solution; then ammonia water is added dropwise to the mixed ion solution to adjust the pH of the solution to 7.0, and then the solution is placed on a heating plate to evaporate to a dark gel until it self-ignites, obtaining a ceramic membrane material precursor; finally, the precursor is calcined at 1080°C for 3 hours to obtain a fluffy and ultra-fine membrane material powder;

[0029] Step two: preparation of dense ceramic membrane

[0030] A certain amount of polyether sulfone is dissolved in solvent N-methyl pyrrolidone to form a polymer solution, and then polyvinyl pyrrolidone and the powder material prepared in step one are added to prepare a uniform slurry. The slurry composition is: 55 wt% membrane material powder, 8 wt% polyether sulfone, 36 wt% N-methyl pyrrolidone, and 1 wt% polyvinyl pyrrolidone. The prepared slurry is transferred to the slurry tank of the extrusion molding device, and after vacuumizing for 20 minutes to exhaust, a mold with an inner tube is used for extrusion molding. Water is used as the core liquid (internal coagulant) in the inner tube during extrusion, and the external coagulant is 80 wt% ethanol aqueous solution. The hollow wet membrane extruded through the mold under a nitrogen pressure of 0.08 MPa is soaked in the external coagulant for 24 hours for solidification, then taken out and dried at room temperature, and then fired at 1300°C for 3 hours, and finally naturally cooled to room temperature in the furnace to obtain a hollow fiber ceramic oxygen permeation membrane.

[0031] The outer diameter of the membrane is about 1.5 mm, the tube wall thickness is about 0.2 μm, and the outer surface microstructure of the membrane is as shown in the attached Figure 1 photograph. The membrane structure is dense, and a large number of praseodymium oxide nanoparticles are formed on the surface.

[0032] Oxygen permeation performance: The high-temperature oxygen permeation performance of the membrane of the present embodiment was determined using a special oxygen permeation flux test device. The silver paste was sealed, the inlet gas side was a mixed gas of 80 vol% air and 20 vol% CO2, the permeation side was swept with high-purity argon gas, the sweep gas flow rate was 100 ml / min, and the working temperature was 925°C. After working for 24 hours and 480 hours, the oxygen fluxes were 1.71 mL·cm -2 ·min -1 and 1.68 mL·cm -2 ·min -1 , respectively, and the flux did not decrease significantly. The results show that the (Pr 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.15 Ta 0.1 )2O 7+δ ceramic membrane has high oxygen permeability and good long-term stability under high-temperature working conditions.

[0033] Example 2

[0034] is also a praseodymium oxide nanoparticle modified (Pr 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.15 Ta 0.1 )2O 7+δCeramic oxygen permeable membrane, the process and parameter conditions of synthesizing the membrane material powder and preparing the dense ceramic membrane are the same as those in Example 1.

[0035] Oxygen permeation performance: The high-temperature oxygen permeation performance of the membrane of the present example was determined by using a special oxygen permeation flux testing device, the silver paste was sealed, the inlet gas side was static dry air, and the sweep gas on the permeation side was high-purity CO2 gas, and the sweep gas flow rate was 100 ml / min. When the working temperature was 925℃, the oxygen fluxes after working for 24 hours and 480 hours were 1.93 mL·cm -2 ·min -1 and 1.96 mL·cm -2 ·min -1 , respectively, and the long-time working flux remained stable. The results show that the (Pr 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.15 Ta 0.1 )2O 7+δ ceramic membrane has high oxygen permeability and good long-term stability under high-temperature CO2 atmosphere working conditions.

[0036] Example 3: (Pr 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.2 Ta 0.05 )2O 7+δ ceramic oxygen permeable membrane modified by nano praseodymium oxide

[0037] The ceramic oxygen permeable membrane material powder was synthesized according to the formula composition (Pr 0.55 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.2 Ta 0.05 )2O 7+δ The process of synthesizing the membrane material powder and preparing the dense ceramic membrane is the same as that in Example 1, and the ceramic oxygen permeable membrane is sintered to be dense at 1320℃ for 3 hours.

[0038] Oxygen permeation performance: The high-temperature oxygen permeation performance of the membrane of the present example was determined by using a special oxygen permeation flux testing device, the silver paste was sealed, the inlet gas side was static dry air, and the sweep gas on the permeation side was high-purity CO2 gas, and the sweep gas flow rate was 100 ml / min. When the working temperature was 925℃, the oxygen fluxes after working for 24 hours and 480 hours were 1.93 mL·cm -2 ·min-1 and 1.57 mL·cm -2 ·min -1 flux remained stable; the results show that the nano-praseodymium oxide modified (Pr 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.2 Ta 0.05 )2O 7+δ ceramic membrane has high oxygen permeability and good long-term stability under high temperature working conditions.

[0039] Example 4: Nano-praseodymium oxide modified (Pr 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.05 Ta 0.2 )2O 7+δ ceramic oxygen permeation membrane

[0040] According to the formula composition (Pr 0.65 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.05 Ta 0.2 )2O 7+δ ceramic oxygen permeation membrane material powder was synthesized. The membrane material powder synthesis and the preparation process of dense ceramic membrane are the same as in Example 1, and the ceramic oxygen permeation membrane is sintered to densification at 1280°C for 3 hours.

[0041] Oxygen permeation performance: the high-temperature oxygen permeation performance of the membrane of the present embodiment was determined by using a special oxygen permeation flux test device, silver paste sealing, the mixed gas of 80 vol% air and 20 vol% CO2 on the inlet side, and high-purity argon gas on the permeation side. The sweep gas flow rate was 100 ml / min; the oxygen fluxes after working for 24 hours and 480 hours were 1.62 mL·cm -2 ·min -1 and 1.56 mL·cm -2 ·min -1 , and the flux did not obviously attenuate; the results show that the nano-praseodymium oxide modified (Pr 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.05 Ta 0.2 )2O 7+δCeramic membranes have high oxygen permeability and good long-term stability under high temperature working conditions.

Claims

1. A layered perovskite-like ceramic oxygen-permeable membrane, characterized in that: The ceramic oxygen-permeable membrane is a layered perovskite-like structure modified with nano-praseodymium oxide particles (Pr). 0.5 Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.25-x Ta x )2O 7+δ (x = 0.05~0.2) Material composition.

2. The method for preparing the layered perovskite-like ceramic oxygen-permeable membrane according to claim 1, characterized in that... Includes the following steps: Step 1: Synthesis of membrane material powder First, according to the formulation of the membrane material, metal nitrate ions were dissolved in an appropriate amount of deionized water. Then, citric acid and EDTA were added at a molar ratio of total metal ions:citric acid:EDTA = 1:1.5:

1. The mixture was stirred continuously for 2 hours to ensure that all components were fully dissolved and the metal ions were fully complexed, resulting in a homogeneous mixed ionic solution. Next, ammonia was added dropwise to the mixed ionic solution to adjust the pH to 7. The solution was then placed on a heating plate to evaporate to a dark gel until it spontaneously combusted, yielding a ceramic membrane material precursor. Finally, the precursor was calcined at 1080℃ for 3 hours to obtain a fluffy, ultrafine powder material. Step 2: Preparation of dense ceramic membrane First, a certain amount of polyethersulfone is dissolved in the solvent N-methylpyrrolidone to form a polymer solution. Then, polyvinylpyrrolidone and the powder material prepared in step one are added to prepare a uniform slurry. The prepared slurry is transferred to the slurry tank of the extrusion molding device. After vacuuming for 20 minutes to remove the exhaust gas, it is extruded using a mold with an inner tube. The hollow wet film extruded through the mold under nitrogen pressure of 0.08 MPa is immersed in an external coagulant for 24 hours to solidify. After solidification, it is taken out and dried at room temperature. Then, it is fired at 1280-1320℃ for 3 hours. Finally, it is naturally cooled to room temperature with the furnace to obtain a hollow fiber ceramic oxygen-permeable membrane.

3. The preparation method according to claim 2, characterized in that: The chemical composition of the ceramic oxygen-permeable membrane is: (Pr 0.5+y Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.25-x Ta x )2O 7+δ , where x = 0.05~0.20 and y = 0.05~0.

15.

4. The preparation method according to claim 3, characterized in that: The chemical composition of the ceramic oxygen-permeable membrane is: (Pr 0.5+y Sr 0.4 Ba 0.1 )3(Fe 0.5 Ni 0.25 Nb 0.25-x Ta x )2O 7+δ , where x = 0.10 and y = 0.

10.

5. The preparation method according to claim 2, characterized in that: In step one, the EDTA needs to be dissolved in diluted ammonia water beforehand.

6. The preparation method according to claim 2, characterized in that: The composition of the slurry in step two is: 55 wt% powder material, 8 wt% polyethersulfone, 36 wt% N-methylpyrrolidone, and 1 wt% polyvinylpyrrolidone.

7. The preparation method according to claim 2, characterized in that: In step two, water is introduced into the die through the inner tube during the extrusion process as an internal coagulant.

8. The preparation method according to claim 2, characterized in that: In step two, the external coagulant is an 80 wt% aqueous ethanol solution.

9. The preparation method according to claim 2, characterized in that: The ceramic oxygen-permeable membrane material can be used as an air electrode material for solid oxide fuel cells / electrolytes.

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