CN103601496A - Diphase mixed conductor oxygen permeation membrane material and preparation method thereof - Google Patents

Abstract

The invention relates to a two-phase mixed conductor oxygen-permeable membrane material and a preparation method thereof, belonging to the technical fields of comprehensive utilization of metallurgical resources and ceramic manufacturing. The structure of the oxygen permeable membrane material is composed of two phases of fluorite type and perovskite type, that is, fluorite type Ce is prepared by sol-gel method respectively._0.8Gd_0.2o_{2- δ}and perovskite-like PrBaCo_xFe_2-xo_{5+ the y}Powder, according to a certain weight percentage, the two-phase powder is mixed, ground, and molded under a certain pressure to obtain a green body, and then at 1130 ~ 1180^oC is baked for 5-8 hours to obtain a two-phase mixed conductor oxygen-permeable membrane. The membrane prepared by the method of the invention has uniform two-phase distribution, compact structure, no impurity phase formation, and good chemical compatibility. at 925^oC. The air flow rate is 300 mlmin^-1and helium flow rate of 100mlmin^-1condition, obtained the 2.81.1

10^-7moles^-1cm^-2It is a kind of oxygen permeable membrane material with application potential.

Description

A kind of two-phase mixed conductor oxygen-permeable membrane material and its preparation method

technical field

The invention relates to a dual-phase mixed conductor oxygen-permeable membrane material and a preparation method thereof, belonging to the technical fields of comprehensive utilization of metallurgical resources and ceramic manufacturing.

Background technique

my country has a huge amount of coal reserves and is one of the countries with the largest coal resources in the world. Coal accounts for more than 60% of the energy composition, and 80% of the raw coal produced is used as fuel. Coal produces a large amount of CO ₂ while promoting economic development. It is speculated that China will replace the United States as the world's largest CO ₂ emitter in the near future. The impact of CO ₂ on global climate change and economy is gradually attracting the attention of the Chinese government, and some measures are being taken to reduce emissions. In order to reduce the emission of greenhouse gases and polluting gases, the methods generally adopted are: (1) reduce the use of energy, especially fossil energy; (2) use low-carbon fuels and effectively use natural gas (especially coke oven gas ), to avoid direct emission or burning; (3) use oxygen-enriched air or pure oxygen instead of air as the combustion oxidant; (4) develop _CO2 capture and storage technology; (5) use nuclear energy and develop new energy to gradually replace fossil energy (6) Other means (including afforestation, promotion of energy conservation and environmental protection fashion and other non-energy field means).

In view of the current energy structure, fossil fuels are still the primary energy source in the world, and it will be the main energy source for a long time to come. Therefore, the realistic approach is to increase the efficiency of fossil energy use in order to reduce the amount of CO ₂ emitted per unit of energy production. Still, the use of fossil fuels inevitably emits large amounts of greenhouse gases. The only way to completely solve this problem is to capture and store the CO ₂ produced by the burning of fossil fuels, rather than letting it be released into the atmosphere. Since the exploitation of fossil fuels has formed a large number of stratum cavities, there is also a large amount of space at the bottom of the ocean to store the captured CO ₂ . It is estimated that the CO ₂ emissions in the next hundred years can be accommodated in it. This is expected to greatly solve the existing greenhouse gas emissions. question. The most critical step in the implementation of this scheme lies in the capture of high-concentration CO ₂ .

As proven, oxyfuel combustion is considered a very promising approach that has received continued attention. In order to solve the source of oxygen-enriched combustion that requires a large amount of oxygen, a mixed-conductor ceramic oxygen-permeable membrane reactor based on the separation of oxygen from air at medium and high temperatures (generally at 800-900°C) has high hopes. The oxygen separation process of the mixed conductor ceramic oxygen permeable membrane is coupled with the combustion process, which can not only reduce at least 35% of the oxygen production loss, but also simplify the process flow and avoid the problem of local overheating of the reactor. The oxygen-enriched combustion process based on mixed-conductor ceramic oxygen-permeable membranes has opened up broad prospects for the application of _oxygen -permeable membranes. Oxygen film material. The literature [Acta Catalytica Sinica, 2009, 30: 801-816] disclosed Ce _0.8 Gd _0.2 O _{2- δ} -Gd _0.2 Sr _0.8 FeO _{3- δ} two-phase mixed conductors, and found that using mixed conductors Gd _0.2 Sr _0.8 FeO _{3- δ} As the hindrance of electrons to oxygen ion transport is smaller, the oxygen permeability is higher. Under the conditions of 950 ^o C and film thickness of 0.5 mm, the oxygen permeability of the dual-phase film is that of the single-phase mixed conductor Gd _0.2 Sr _0.8 FeO _{3- δ} 2 times. The literature [Angewandte Chemie International Edition, 2011, 50: 759-763] used a one-step synthesis method to prepare a fluorite-spinel Ce _0.9 Gd _0.1 O _{2- δ} -NiFe ₂ O ₄ dual-phase mixed conductor film, and In situ X-ray diffraction and stability experiments demonstrate that the biphasic oxygen-permeable membrane exhibits excellent _CO2 corrosion resistance at high temperatures.

Contents of the invention

In view of the defects existing in the prior art, the object of the present invention is to provide a two-phase mixed conductor oxygen-permeable membrane material and a preparation method thereof.

To achieve the above object, the present invention adopts the following technical solutions:

A two-phase mixed conductor oxygen-permeable membrane material has the following composition and weight percentage:

Ce _0.8 Gd _0.2 O _{2- δ} oxide 60%

PrBaCo _x Fe _{2- x} O _{5+ y} oxide 40%

The values of x are 0, 0.5, 1.0, 1.5 and 2.0; δ is the oxygen vacancy in Ce _0.8 Gd _0.2 O _{2- δ} oxide, and the value of δ is between 0 and 0.1; y is PrBaCo _x Fe Oxygen vacancies in _{2- x} O _{5+ y} oxides, where the value of y is between 0 and 0.5.

A preparation method of a dual-phase mixed conductor oxygen-permeable membrane material has the following process and steps:

(a) According to the stoichiometric ratio of Ce _0.8 Gd _0.2 O _{2- δ ,} add a certain amount of cerium salt and Gd ₂ O ₃ into the aqueous solution of nitric acid, heat and stir until completely dissolved; by metal ion: ethylenediaminetetraacetic acid : The substance ratio of citric acid is 1:1:1.5, accurately weigh the quality of ethylenediaminetetraacetic acid and citric acid, add them to distilled water, heat and stir until the organic matter dissolves;

(b) Mix the two solutions obtained in step (a), and stir at 90-100 ^o C, add ammonia water dropwise to make the pH of the solution between 7 and 8, and keep heating and stirring until the solution turns into a sol shape; dry the resulting sol-like substance at 130-150 ^o C until it expands into a spongy porous solid, take it out, and bake it at 350-450 ^o C for 12-24 hours; grind the obtained solid evenly, and dry it at 650-750 ^o C roasting for 5-8 hours to obtain Ce _0.8 Gd _0.2 O _{2- δ} powder;

(c) Add a certain amount of Pr ₂ O ₃ , barium salt, cobalt salt and iron salt into the aqueous solution of nitric acid according to the stoichiometric ratio of PrBaCo _x Fe _{2- x} O _{5+ y} , heat and stir until completely dissolved; press Metal ions: ethylenediaminetetraacetic acid: the ratio of citric acid to substance is 1:1:1.5, accurately weigh the quality of ethylenediaminetetraacetic acid and citric acid, add it to distilled water, heat and stir, until the organic matter dissolves;

(d) Mix the two solutions obtained in step (c) and stir them at 90-100 ^o C, add ammonia water dropwise to make the pH value of the solution between 7 and 8, and keep heating and stirring until the solution turns into a sol shape; dry the obtained sol-like substance at 130-150 ^o C until it expands into a spongy porous solid, take it out, and bake it at 350-450 ^o C for 12-24 hours; grind the obtained solid evenly, and dry it at 800-950 ^o C roasting for 2 to 5 hours to obtain PrBaCo _x Fe _{2- x} O _{5+ y} powder;

(e) Weigh the two powders obtained in step (b) and step (d) according to a mass ratio of 6:4, and grind them in a mortar for 3 to 4 hours to mix them evenly, and add Appropriate amount of oleic acid, and molded under the pressure of 100-150MPa, and the obtained sheet-shaped green body was baked at 1130-1180 ^o C for 5-8 hours, and the two-phase mixed conductor oxygen-permeable membrane was obtained.

Compared with the prior art, the present invention has the following prominent substantive features and significant advantages:

The biphasic oxygen-permeable membrane prepared by the present invention has uniform two-phase distribution, compact structure, no impurity phase generation, and good chemical compatibility; and has high oxygen permeability, and has better oxygen permeability under _CO2- containing atmosphere. stability.

Description of drawings

Fig. 1 is the X-ray diffraction (XRD) of Ce _0.8 Gd _0.2 O _{2- δ} -PrBaCo ₂ O _{5+ y} (CG-PBC ₂ ) single-phase oxygen-permeable films and dual-phase oxygen-permeable films prepared by the method of the present invention picture.

Fig. 2 is a backscattered scanning electron (BSEM) photo of the surface of the Ce _0.8 Gd _0.2 O _{2- δ} -PrBaCo ₂ O _{5+ y} (CG-PBC ₂ ) biphasic oxygen-permeable membrane prepared by the method of the present invention.

Fig. 3 is a graph showing the variation of oxygen permeability with temperature of the Ce _0.8 Gd _0.2 O _{2- δ} -PrBaCo ₂ O _{5+ y} (CG-PBC ₂ ) biphasic oxygen permeable membrane prepared by the method of the present invention.

Fig. 4 shows the oxygen permeability of the Ce _0.8 Gd _0.2 O _{2- δ} -PrBaCo ₂ O _{5+ y} (CG-PBC ₂ ) biphasic oxygen-permeable membrane prepared by the method of the present invention in atmospheres with different CO ₂ concentrations.

Detailed ways

Specific embodiments of the present invention are now described in the following.

Example 1

Add 39.566 g Ce(NO ₃ ) ₃ 6H ₂ O and 4.129 g Gd ₂ O ₃ into the aqueous solution of nitric acid, heat and stir until completely dissolved; Accurately weigh ethylenediaminetetraacetic acid and citric acid at a ratio of 1:1:1.5, add them to distilled water, heat and stir until the organic matter is dissolved; mix the above two solutions and stir at 95 ^o C , by adding ammonia water dropwise, the pH value of the solution was 7, heated and stirred continuously until the solution became a sol-like substance; the obtained sol-like substance was dried at 150 ^o C until it expanded into a spongy porous solid, and then taken out at 400 ^{o C} C roasting for 18 hours; grind the obtained solid evenly, and roast at 650 ^o C for 5 hours to obtain Ce _0.8 Gd _0.2 O _{2- δ} (CG) powder;

18.266 g Pr(NO ₃ ) ₃ 6H ₂ O, 10.976 g Ba(NO ₃ ) ₂ and 24.447 g Co(NO ₃ ) ₂ 6H ₂ O were dissolved in deionized water to obtain 49.096 g EDTA and Dissolve 48.419 g of citric acid in another beaker with a certain amount of deionized water, mix the above two solutions, and heat to 95 ^o C, add ammonia water dropwise to make the pH of the solution 7, continue heating until a sol-like substance is obtained . The resulting sol was dried at 150 ^o C until it swelled into a spongy porous solid, then it was fired at 350 ^o C for 10 hours, and then at 850 ^o C for 5 hours to obtain PrBaCo ₂ O _{5+ y} (PBC ₂ ) powder. Weigh the corresponding powder according to the mass ratio of Ce _0.8 Gd _0.2 O _{2- δ} : PrBaCo ₂ O _{5+ y} of 6:4, and grind it in a mortar for 3 hours to make it evenly mixed, and add Appropriate amount of oleic acid, and molded under 120MPa pressure, the resulting flake green body was roasted at 1150 ^o C for 6 hours to obtain Ce _0.8 Gd _0.2 O _{2- δ} -PrBaCo ₂ O _{5+ y} (CG-PBC ₂ ) two-phase mixture Conductor oxygen permeable membrane.

Example 2

Ce _0.8 Gd _0.2 O _{2- δ} (CG) powder was prepared in exactly the same manner as in Example 1 above.

18.266 g Pr(NO ₃ ) ₃ 6H ₂ O, 10.976 g Ba(NO ₃ ) ₂ , 18.335 g Co(NO ₃ ) ₂ 6H ₂ O and 8.484 g Fe(NO ₃ ) ₃ 9H ₂ O were dissolved in In deionized water, dissolve 49.096 g of ethylenediaminetetraacetic acid and 48.419 g of citric acid in another beaker filled with a certain amount of deionized water, mix the above two solutions, and heat to 95 ^o C, and dissolve the solution by adding ammonia water dropwise The pH value was 7, and heating was continued until a sol-like substance was obtained. The resulting sol was dried at 160 ^o C until it swelled into a spongy porous solid, then it was calcined at 400 ^o C for 12 hours, and then at 850 ^o C for 5 hours to obtain PrBaCo _1.5 Fe _0.5 O _{5+ y} ( PBC _1.5 F _0.5 ) powder. Weigh the corresponding powder according to the mass ratio of Ce _0.8 Gd _0.2 O _{2- δ} : PrBaCo _1.5 Fe _0.5 O _{5+ y} is 6:4, and grind it in a mortar for 3 hours to make it evenly mixed, and add to the obtained powder Add an appropriate amount of oleic acid to it, and shape it under 120MPa pressure, and the obtained flake green body is roasted at 1150 ^o C for 5 hours to obtain Ce _0.8 Gd _0.2 O _{2- δ} -PrBaCo _1.5 Fe _0.5 O _{5+ y} (CG-PBC _1.5 F _0.5 ) Two-phase mixed conductor oxygen-permeable membrane.

Example 3

Ce _0.8 Gd _0.2 O _{2- δ} (CG) powder was prepared in exactly the same manner as in Example 1 above.

18.266 g Pr(NO ₃ ) ₃ 6H ₂ O, 10.976 g Ba(NO ₃ ) ₂ , 12.223 g Co(NO ₃ ) ₂ 6H ₂ O and 16.969 g Fe(NO ₃ ) ₃ 9H ₂ O were dissolved in In deionized water, dissolve 49.096 g of ethylenediaminetetraacetic acid and 48.419 g of citric acid in another beaker filled with a certain amount of deionized water, mix the above two solutions, and heat to 95 ^o C, and dissolve the solution by adding ammonia water dropwise The pH value was 7, and heating was continued until a sol-like substance was obtained. Dry the obtained sol at 160 ^o C until it expands into a spongy porous solid, then take it out, bake it at 400 ^o C for 12 hours, and then bake it at 850 ^o C for 5 hours to obtain PrBaCoFeO _{5+ y} (PBCF) powder . Weigh the corresponding powder according to the mass ratio of Ce _0.8 Gd _0.2 O _{2- δ} : PrBaCoFeO _{5+ y} of 6:4, and grind it in a mortar for 3 hours to make it evenly mixed, and add an appropriate amount of oil to the obtained powder acid, and molded under a pressure of 120MPa, the resulting sheet-shaped body was fired at 1150 ^o C for 5 hours to obtain a Ce _0.8 Gd _0.2 O _{2- δ} -PrBaCoFeO _{5+ y} (CG-PBCF) two-phase mixed conductor oxygen-permeable membrane.

Example 4

Ce _0.8 Gd _0.2 O _{2- δ} (CG) powder was prepared in exactly the same manner as in Example 1 above.

18.266 g Pr(NO ₃ ) ₃ 6H ₂ O, 10.976 g Ba(NO ₃ ) ₂ , 6.112 g Co(NO ₃ ) ₂ 6H ₂ O and 25.453 g Fe(NO ₃ ) ₃ 9H ₂ O were dissolved in In deionized water, dissolve 49.096 g of ethylenediaminetetraacetic acid and 48.419 g of citric acid in another beaker filled with a certain amount of deionized water, mix the above two solutions, and heat to 95 ^o C, and dissolve the solution by adding ammonia water dropwise The pH value was 7, and heating was continued until a sol-like substance was obtained. The resulting sol was dried at 150 ^o C until it swelled into a spongy porous solid, then it was calcined at 400 ^o C for 15 hours, and then at 850 ^o C for 6 hours to obtain PrBaCo _0.5 Fe _1.5 O _{5+ y} ( PBC _0.5 F _1.5 ) powder. Weigh the corresponding powder according to the mass ratio of Ce _0.8 Gd _0.2 O _{2- δ} : PrBaCo _0.5 Fe _1.5 O _{5+ y} is 6:4, and grind it in a mortar for 3 hours to make it evenly mixed, and add to the obtained powder Add an appropriate amount of oleic acid to the mixture and mold it under a pressure of 120MPa. The obtained flake green body was fired at 1150 ^o C for 5 hours to obtain Ce _0.8 Gd _0.2 O _{2- δ} -PrBaCo _0.5 Fe _1.5 O _{5+ y} (CG-PBC _0.5 F _1.5 ) Two-phase mixed conductor oxygen-permeable membrane.

Example 5

Ce _0.8 Gd _0.2 O _{2- δ} (CG) powder was prepared in exactly the same manner as in Example 1 above.

Dissolve 18.266 g Pr(NO ₃ ) ₃ 6H ₂ O, 10.976 g Ba(NO ₃ ) ₂ and 33.938 g Fe(NO ₃ ) ₃ 9H ₂ O in deionized water, take 49.096 g EDTA and Dissolve 48.419 g of citric acid in another beaker with a certain amount of deionized water, mix the above two solutions, and heat to 95 ^o C, add ammonia water dropwise to make the pH of the solution 7, continue heating until a sol-like substance is obtained . The resulting sol was dried at 160 ^o C until it swelled into a spongy porous solid, then calcined at 400 ^o C for 12 hours, and then at 850 ^o C for 5 hours to obtain PrBaFe ₂ O _{5+ y} (PBF ₂ ) powder. Weigh the corresponding powder according to the mass ratio of Ce _0.8 Gd _0.2 O _{2- δ} : PrBaFe ₂ O _{5+ y} of 6:4, grind it in a mortar for 3 hours, make it evenly mixed, and add Appropriate amount of oleic acid, and molded under 120MPa pressure, the resulting flake green body was roasted at 1150 ^o C for 5 hours to obtain Ce _0.8 Gd _0.2 O _{2- δ} -PrBaFe ₂ O _{5+ y} (CG-PBF ₂ ) two-phase mixture Conductor oxygen permeable membrane.

evaluation test

10^-7 mol s^-1cm^-2的高透氧量，当吹扫气中含有少量CO₂时，其氧的渗透性能降低趋势较为缓慢，具有较好的稳定性能。  Under the conditions of 925 ^o C, air flow rate of 300 ml min ^-1 and helium flow rate of 100 ml min ^-1 , Ce _0.8 Gd _0.2 O _{2- δ} -PrBaCo ₂ O _{5+ y} biphasic oxygen permeable membrane obtained 2.81.1

With a high oxygen permeability of 10 ^-7 mol s ^-1 cm ^-2 , when the sweeping gas contains a small amount of CO ₂ , the oxygen permeability decreases slowly and has good stability.

Claims (2)

1. A two-phase mixed conductor oxygen-permeable film material, characterized in that it has the following composition and weight percentage: Ce _0.8 Gd _0.2 O _{2- δ} oxide 60% PrBaCo _x Fe _{2- x} O _{5+ y} oxide 40% The values of x are 0, 0.5, 1.0, 1.5 and 2.0; δ is the oxygen vacancy in Ce _0.8 Gd _0.2 O _{2- δ} oxide, and the value of δ is between 0 and 0.1; y is PrBaCo _x Fe Oxygen vacancies in _{2- x} O _{5+ y} oxides, where the value of y is between 0 and 0.5. 2. A preparation method of a two-phase mixed conductor oxygen-permeable membrane material, characterized in that it has the following processes and steps: (a) According to the stoichiometric ratio of Ce _0.8 Gd _0.2 O _{2- δ ,} add a certain amount of cerium salt and Gd ₂ O ₃ into the aqueous solution of nitric acid, heat and stir until completely dissolved; by metal ion: ethylenediaminetetraacetic acid : The substance ratio of citric acid is 1:1:1.5, accurately weigh the quality of ethylenediaminetetraacetic acid and citric acid, add them to distilled water, heat and stir until the organic matter dissolves; (b) Mix the two solutions obtained in step (a), and stir at 90-100 ^o C, add ammonia water dropwise to make the pH of the solution between 7 and 8, and keep heating and stirring until the solution turns into a sol shape; dry the resulting sol-like substance at 130-150 ^o C until it expands into a spongy porous solid, take it out, and bake it at 350-450 ^o C for 12-24 hours; grind the obtained solid evenly, and dry it at 650-750 ^o C roasting for 5-8 hours to obtain Ce _0.8 Gd _0.2 O _{2- δ} powder; (c) Add a certain amount of Pr ₂ O ₃ , barium salt, cobalt salt and iron salt into the aqueous solution of nitric acid according to the stoichiometric ratio of PrBaCo _x Fe _{2- x} O _{5+ y} , heat and stir until completely dissolved; press Metal ions: ethylenediaminetetraacetic acid: the ratio of citric acid to substance is 1:1:1.5, accurately weigh the quality of ethylenediaminetetraacetic acid and citric acid, add it to distilled water, heat and stir, until the organic matter dissolves; (d) Mix the two solutions obtained in step (c) and stir them at 90-100 ^o C, add ammonia water dropwise to make the pH value of the solution between 7 and 8, and keep heating and stirring until the solution turns into a sol shape; dry the obtained sol-like substance at 130-150 ^o C until it expands into a spongy porous solid, take it out, and bake it at 350-450 ^o C for 12-24 hours; grind the obtained solid evenly, and dry it at 800-950 ^o C roasting for 2 to 5 hours to obtain PrBaCo _x Fe _{2- x} O _{5+ y} powder; (e) Weigh the two powders obtained in step (b) and step (d) according to a mass ratio of 6:4, and grind them in a mortar for 3 to 4 hours to mix them evenly, and add Appropriate amount of oleic acid, and molded under the pressure of 100-150MPa, and the obtained sheet-shaped green body was baked at 1130-1180 ^o C for 5-8 hours, and the two-phase mixed conductor oxygen-permeable membrane was obtained.

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