Integrated carbon dioxide separation membrane, catalytic system, preparation method of integrated carbon dioxide separation membrane and catalytic system, and application of integrated carbon dioxide separation membrane and catalytic system in carbon dioxide trapping-reforming

Abstract

The invention discloses an integrated carbon dioxide separation membrane, a catalytic system, a preparation method of the integrated carbon dioxide separation membrane and a catalytic system and application of the integrated carbon dioxide separation membrane and the catalytic system to capture-reforming of carbon dioxide, the carbon dioxide separation membrane is an asymmetric mixed oxygen ion-carbonate ion conductor membrane, and molten carbonate is permeated into high-temperature calcined GDC; the capture and conduction of CO2 under a high-temperature condition are realized by means of molten carbonate, charge balance is realized by means of a permeable layer with high O2-ion conductivity, and a porous BYC7 / GDC support layer is added below the permeable layer to ensure the mechanical strength of the membrane during high-temperature permeation. And then the carbon dioxide separation membrane is combined with the catalyst, so that the original form of the catalyst can be kept by placing the catalyst granules below the separation membrane, more active sites can be exposed, and the highest CO2 conversion rate is achieved. The prepared integrated CO2 separation membrane and catalyst system is used for testing in a simulated flue gas environment, the highest CO2 permeability can reach 1.86 ml.min <-1 >. Cm <-2 >, and the CO2 conversion rate in a 210h stability test is kept at 90% or above.

Description

Technical Field

[0001] The present invention relates to the field of CO2 capture and utilization, and in particular to a preparation method and application of an integrated CO2 separation membrane and catalytic system for CO2 capture-reforming conversion. Background Art

[0002] With rapid socioeconomic development and the continued growth of the global population, the impact of human activities on the environment is becoming increasingly severe. Greenhouse gas emissions, particularly from the overexploitation and utilization of fossil fuels, have led to global warming, extreme weather events, and other issues, becoming the most pressing global environmental challenge today. However, traditional fossil fuels will continue to dominate energy consumption for decades to come, making the capture and utilization of CO2 from coal-fired power plant exhaust particularly important. CO2 capture can be achieved through a variety of technologies, including amine absorption, adsorption using alkaline or porous materials, and membrane separation. However, amine solvent absorption operates under high hydrothermal conditions and requires significant heat regeneration, and the generated CO2 often requires purification before further utilization. Alkaline or porous materials can capture CO2 through gas-solid reactions, but these methods suffer from low absorption rates, poor selectivity, and weak binding. Membrane separation technology allows for high-temperature continuous feed separation, and the modular design and integration of membrane modules facilitate the design of integrated systems. Carbon dioxide itself is a carbon source and can be converted into high-value-added chemicals through methane dry reforming, CO2 hydrogenation, and reverse water-gas shift reactions. There are many reports on both technologies, but the traditional carbon dioxide capture and utilization processes are carried out separately, which inevitably increases transportation costs. In order to reduce or even eliminate this cost, the integration of carbon dioxide capture and utilization is very promising. Carbon dioxide capture and utilization aims to capture carbon dioxide from mixed gases and other emission sources and convert it into chemicals or energy with higher added value. Patent application number 201710028366.3 discloses a new and efficient method for preparing a two-phase electrochemical separation membrane: this method uses a carbonate aqueous solution as a curing agent to prepare two membrane materials with good compatibility by means of low-temperature curing of carbonate and high-temperature impregnation of carbonate, but the CO2 permeability at 700°C is only 0.3mL·min -1 cm -2 Patent application number 202310850782.7 discloses a catalyst for carbon dioxide capture-conversion coupling in flue gas and its preparation method and application: the method uses M in the hydrotalcite layer structure to 3+ / 4+The capture and release of CO2 is achieved by using variable-valence metal ions. The CO2 hydrogenation reaction is catalyzed by Pd, Pt, Au, and Au precious metals. Although this method has a simple preparation process and can achieve efficient CO2 capture and conversion, the introduction of precious metals greatly increases the cost of raw materials. At the same time, the reaction process requires switching the atmosphere and pressurization operations, which are not suitable for large-scale industrial production. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology. In view of the problems of complex hydrothermal conditions for CO2 absorption by amine solvents, low adsorption fastness of alkaline and porous materials, and low permeability of membrane technology, the present invention proposes a method for preparing CO2 separation membranes and selectively capturing CO2 under simulated flue gas environments; and explores the method of combining membranes and catalysts, and proposes an integrated capture-conversion system to achieve high-temperature CO2 capture and reforming conversion.

[0004] The technical purpose of the present invention is achieved through the following technical solutions.

[0005] The integrated carbon dioxide separation membrane is a mixed oxygen ion-carbonate ion conductor membrane formed by molten carbonate permeating into porous GDC, including a permeation layer and a support layer, wherein:

[0006] Molten carbonate and porous GDC are used as the permeation layer, and the GDC composition is Ce 0.9 Gd 0.1 O 1.95 The permeable layer uses molten carbonate to capture CO2 and CO3 at high temperature. 2- Transmission, with the help of GDC to achieve high O 2- Ionic conduction balances the charge.

[0007] The support layer is GDC / BYC7, and the BYC7 composition is (Bi 0.75 Y 0.25 ) 0.93 Ce 0.07 O 1.5±δ Defective metal oxides. GDC / BYC7 powders are weighed at a mass ratio of (3-5) GDC:BYC7 (1-2). Carbon black and PVDF are added, ball-milled, and dried to obtain a GDC / BYC7 mixture. The mixture is then pressed into tablets and calcined at 1000-1200 degrees Celsius in air. A support layer is placed beneath the permeation layer to ensure mechanical strength and stability during high-temperature permeation.

[0008] In the above technical solution, the permeation layer, as a CO2 capture material, needs to have the ability to transmit both oxygen ions and carbonate ions. The selected molten carbonate is at least one of lithium carbonate, sodium carbonate, and potassium carbonate, preferably a eutectic mixture of Li2CO3 and Na2CO3, with a molar ratio of Li2CO3 to Na2CO3 of 52:48.

[0009] In the above technical solution, the thickness of the permeation layer is 50 to 300 μm, preferably 50 to 100 μm.

[0010] In the above technical solution, the thickness of the support layer is 500-1725 μm, preferably 800-1200 μm.

[0011] The preparation method of the integrated carbon dioxide separation membrane is carried out according to the following steps:

[0012] Step 1: Preparation of asymmetric membrane materials

[0013] GDC powder, GDC / BYC7 mixture and GDC powder are placed in a mold in sequence. After the powder is pressed into tablets, the resulting product is placed in an air atmosphere and heated from room temperature (20-30 degrees Celsius) to 1000-1200 degrees Celsius for high-temperature calcination for 5-8 hours. The product is then naturally cooled to room temperature (20-30 degrees Celsius) to obtain a GDC-GDC / BYC7-GDC membrane. The GDC layer on one side is then ground off to obtain an asymmetric membrane material with a support layer of GDC / BYC7 and a permeation layer of GDC.

[0014] BYC7 is composed of (Bi 0.75 Y 0.25 ) 0.93 Ce 0.07 O 1.5±δ The preparation process is as follows: according to its composition, metal nitrates of bismuth, yttrium, and cerium and citric acid are dissolved in a dilute nitric acid solution, and the molar ratio of citric acid to total metal ions (the sum of bismuth, yttrium, and cerium ions) is (1-2):1. Water is evaporated in a constant temperature water bath at 60-80°C to obtain a gel, which is then heated in a heating mantle until spontaneous combustion to obtain a black fluffy solid. After grinding, the solid is heated from room temperature (20-30°C) to 500-800°C in an air atmosphere at a rate of 1-5°C / min and calcined at this temperature for 4-6 hours. After cooling and grinding, the solid is obtained as BYC7 powder.

[0015] The GDC / BYC7 mixture is prepared by weighing GDC and BYC7 powders in a mass ratio of (3-5) GDC:BYC7:(1-2), weighing carbon black in an amount of 5-20 wt% of the total mass of carbon black, GDC and BYC7, and weighing PVDF in an amount of 1-5% of the total mass of the mixture, mixing the four, ball milling and drying to obtain a GDC / BYC7 mixture;

[0016] Step 2, Molten Carbonate Infiltration

[0017] The molten carbonate is placed above the permeation layer, heated to 500-800 degrees Celsius and kept warm, so that the molten carbonate can penetrate into the GDC voids of the permeation layer in situ to form a dense membrane material.

[0018] In step 1, the temperature is raised from room temperature (20-30 degrees Celsius) to 1000-1200 degrees Celsius at a rate of 1-5 degrees Celsius per minute for high-temperature calcination. The calcination time is 5-8 hours, preferably 6-8 hours.

[0019] In step 1, the thickness of the support layer and the permeation layer are adjusted according to the amount of GDC powder and the 5C-GDC / BYC7 mixture used. After tableting, a permeation layer with a thickness of 50 to 300 μm and a support layer with a thickness of 500 to 1725 μm will be obtained; preferably, the permeation layer thickness is 50 to 100 μm and the support layer thickness is 800 to 1200 μm.

[0020] In step 1, water is evaporated in a constant temperature water bath at 60-80°C to obtain a gel, which is then heated in a heating mantle until spontaneous combustion to obtain a black fluffy solid. After grinding, the solid is heated from room temperature (20-30°C) to 700-800°C in an air atmosphere at a heating rate of 1-5°C / min and calcined for 5-6 hours. The solid is then cooled in the furnace and ground to obtain BYC7 powder.

[0021] In step 1, when carbon black, GDC and BYC7 are ball-milled, 40 mL of ethanol and 60 g of balls are added, wherein the mass ratio of large balls: medium balls: small balls is 2:5:3, and the ball milling is carried out at 200-400 rpm for 5-8 hours, and then dried in an oven at 100-120°C for 10-12 hours to obtain GDC / BYC7; the purpose of adding carbon black is to serve as a pore-forming agent, and the added mass fraction accounts for 5-10 wt% of the total mass of the powder; PVDF is used as a binder, and the amount used is 1-5% of the total mass.

[0022] In step 1, GDC powder, a GDC / BYC7 mixture, and GDC powder are sequentially pressed into a stainless steel mold. A powder tablet press is used to maintain a pressure of 150 to 200 MPa for 1 to 3 minutes to form the powder into tablets. GDC is placed on both sides of the GDC / BYC7 to prevent cracks in the GDC / BYC7 layer during the preparation process.

[0023] In step 1, after obtaining the GDC-GDC / BYC7-GDC film, SiC paper is used to polish and remove the GDC layer on one side to obtain an asymmetric film material.

[0024] In step 2, the molten carbonate is at least one of lithium carbonate, sodium carbonate, and potassium carbonate, preferably a eutectic mixture of Li2CO3 and Na2CO3, with a molar ratio of Li2CO3 to Na2CO3 of 52:48.

[0025] In step 2, the molten carbonate is ball-milled in a ball mill at 200-300 rpm for 6-8 hours, and then dried at 60-80° C. for 10-15 hours, preferably 10-12 hours. The ball-milled molten carbonate is melted at 500-800° C. for 1-3 hours, and after cooling, the carbonate is ground to obtain a submicron powder.

[0026] In step 2, the temperature was kept at room temperature (20-30 degrees Celsius) for 1-5 degrees Celsius min. -1 The temperature is raised to 500-800°C at a heating rate of 100-200°C and kept warm for 1-3 hours, so that the molten carbonate can penetrate into the voids of the permeation layer GDC in situ to form a dense membrane material.

[0027] The catalytic system based on the integrated carbon dioxide separation membrane takes the integrated carbon dioxide separation membrane as the main body, and a catalyst precursor for methane dry reforming is set on one side of the support layer GDC / BYC7. When used subsequently, it is first reduced with hydrogen, and then gases containing carbon dioxide and methane are introduced above the permeation layer and below the catalyst respectively. Due to the action of the permeation layer, carbon dioxide is captured and combined with methane to undergo dry reforming reaction at the catalyst.

[0028] The catalyst used for the reforming conversion can be any catalyst that has high activity when tested alone, such as Ni / CeO2, Ni-LaAlO3 / Al2O3, Ni-CeAlO3 / CeO2, and the like. Here, Ni / CeO2 is taken as an example: nickel nitrate is evenly dispersed in deionized water, cerium oxide powder is added, and stirred so that the CeO2 powder fully absorbs the impregnation solution. After the absorption equilibrium is reached, the impregnation is terminated. The solution is then dried, and after it is completely dried, the obtained powder is ground and heated in an air atmosphere at a speed of 1-5 degrees Celsius per minute from room temperature of 20-30 degrees Celsius. The temperature is raised to 800-1100°C and kept warm for calcination for 1-3 hours to obtain a catalyst precursor in the form of NiO / CeO2 with a nickel loading of 1-10 wt%. Correspondingly, the catalyst precursors are NiO-LaAlO3 / Al2O3 and NiO-CeAlO3 / CeO2. For detailed preparation methods, please refer to the previous research results of this research group - Chinese invention patent application "A high specific surface area Ni-based perovskite catalyst, its preparation method and application in methane dry reforming", application number 2025104181199, and application date April 3, 2025.

[0029] In the above technical solution, after adding cerium oxide powder, stirring is carried out at room temperature of 20-30 degrees Celsius at 300-500 revolutions per minute for 4-6 hours to allow the CeO2 powder to fully absorb the impregnation solution.

[0030] In the above technical solution, after the impregnation is completed, the solution is transferred to a 60-80° C. forced air drying oven for drying.

[0031] In the above technical solution, the loading amount of elemental nickel is 5-10 wt% (the ratio of the mass of elemental nickel to the total mass of the catalyst precursor).

[0032] The catalyst precursor is placed on the GDC / BYC7 support layer of the integrated carbon dioxide separation membrane by co-pressing, screen printing or pelletizing.

[0033] (1) Granulation method: Take the NiO / CeO2 catalyst precursor and press it into tablets, crush it into granules, and sieve it to obtain catalyst precursor particles with a certain strength. The particles are placed under the support layer.

[0034] (2) Screen printing method: Mix the catalyst precursor NiO / CeO2 with the binder PVB, stir evenly, and pour the slurry evenly on one end of the screen. Fix the screen on the printing table, and lay the integrated carbon dioxide separation membrane flat underneath (with the support layer facing up). Use a scraper to scrape the screen at a constant speed and pressure, repeat the scraping, slowly lift the screen, check the uniformity of the coating, let it stand at room temperature, and then transfer it to an oven for drying. Finally, transfer it to a muffle furnace and calcine it at 300-500℃ for 1-3 hours.

[0035] (3) Co-pressing method: GDC, catalyst precursor NiO / CeO2, GDC / BYC7 mixture, and GDC are pressed into a stainless steel mold in sequence. After forming using a powder tablet press, the GDC on the side close to the catalyst precursor is ground off using SiC paper. The asymmetric membrane containing the catalyst is then calcined at 1000-1200°C in an alumina crucible for 5-8 hours.

[0036] The integrated carbon dioxide separation membrane of the present invention and the catalytic system based on the integrated carbon dioxide separation membrane are used in carbon dioxide capture and carbon dioxide capture-reforming.

[0037] Compared with the prior art, the beneficial effects of the invention are:

[0038] (1) The present invention adopts an asymmetric mixed oxygen ion-carbonate ion conductor membrane preparation method. With the help of the permeation layer formed by the mixture of oxygen-rich ion conductor GDC and carbonate-rich ion conductor molten carbonate, rapid CO2 capture and conduction can be achieved. The porous BYC7 / GDC support layer not only ensures the good stability of the membrane at high temperature but also can further reduce the thickness of the permeation layer to achieve efficient CO2 conduction, so that the final membrane material can not only meet the high-temperature permeation requirements but also can be effectively integrated through different tableting methods.

[0039] (2) The present invention studies the effect of the thickness of the asymmetric membrane support layer and the permeation layer on the CO2 capture capacity and finds that within a certain range of permeation layer thickness, the CO2 permeability decreases with the increase of the permeation layer thickness. When the permeation layer thickness is fixed, the carbon dioxide permeability decreases with the increase of the support layer thickness. However, for the same permeation layer thickness, the carbon dioxide permeability does not increase with the decrease of the support layer thickness. Instead, when the support layer thickness is between the intermediate values, the membrane does not show the highest permeability, which can reach up to 1.12 mL min. -1 cm -2 , which is about three times that of the reported membrane materials. Under the same conditions, the CO2 capture capacity is higher than that reported in the current literature.

[0040] (3) The present invention studies the method of combining CO2 capture and catalyst, and designs a method of combining CO2 capture and in-situ conversion. This method can ensure that the membrane and catalyst are at 800℃ and 60000mL. -1 ·h -1 ·g -1 The stability test results for 210 hours showed that the CH4 conversion rate remained at 100%, the CO2 conversion rate remained at around 90%, and the CO2 permeation rate was as high as 1.86 mL min -1 cm -2, which provided ideas for the final design of an integrated CO2 capture and conversion system with good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 These are SEM photos of the CO2 separation membranes of the present invention having permeation layers and support layers of different thicknesses.

[0042] Figure 2 This is a comparison curve of the permeability of the CO2 separation membranes of the present invention with different permeation layer and support layer thicknesses.

[0043] Figure 3 Schematic diagram of the reaction device and gas path during the test of the present invention, wherein 1 is a CO2 gas cylinder; 2 is an N2 gas cylinder; 3 is a CH4 gas cylinder; 4 is an Ar gas cylinder; 5 is a mass flow controller; 6 is a tubular furnace; 7 is a temperature probe; 8 is a first alumina tube; 9 is a second alumina tube; 10 is an air inlet pipe; 11 is a purge air pipe; 12 is an air outlet pipe; and 13 is a gas chromatograph. Figure 4 This is a graph showing the conversion rate and hydrogen-to-carbon ratio of the methane dry reforming reaction using the integrated CO2 separation membrane and catalytic system implemented using different methods of the present invention.

[0044] Figure 5 The granulation method of the present invention realizes the integration of CO2 separation membrane and catalytic system at 800℃ and 60000mL·h -1 ·g -1 Graph showing the results of a 210-hour stability test at airspeed.

[0045] Figure 6 These are SEM images of the CO2 separation membrane after stability testing in the present invention, where (a) corresponds to the overall cross section; (b) corresponds to the cross section of the permeation layer; (c) corresponds to the support layer close to the permeation layer; and (d) corresponds to the support layer far from the permeation layer. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0047] Example 1

[0048] Take the CO2 separation membrane with a support layer (BYC7 / GDC) thickness of 1000μm and a permeation layer (GDC) thickness of 80μm as an example, and the process of integrating the catalyst and the membrane by granulation method:

[0049] Step 1, preparation of a CO2 separation membrane with a support layer thickness of 1000 μm and a permeation layer thickness of 80 μm:

[0050] (1) BYC7 powder was prepared by the citric acid nitrate method. 10.1505g Bi(NO3)3·5H2O, 2.6715g Y(NO3)3·6H2O, and 0.9119g Ce(NO3)3·6H2O were dissolved in 10mL (6.5-6.8% by mass) of dilute nitric acid solution and stirred until completely dissolved. 9.4563g citric acid was added to the mixed solution and stirred continuously for 5min at room temperature (20-30°C) (stirring speed: 200 rpm). The whole was then transferred to a constant temperature water bath at 80°C to evaporate most of the water to obtain a gel, which was then heated to spontaneous combustion to obtain a black fluffy solid. After the solid was ground, it was heated in a muffle furnace under air atmosphere at a heating rate of 3°C / min from room temperature (20-30°C) to 700°C and kept at this temperature for 5h. The BYC7 powder was cooled in the furnace to obtain BYC7 powder for later use.

[0051] Preparation of supporting layer material: Take 2.6 g of commercial GDC powder (purchased from Ningbo Suofuren Energy Technology Co., Ltd., gadolinium oxide doped cerium oxide, GDC) and 1 g of BYC7 powder, add 0.18 g of carbon black and 0.04 g of PVDF and put them into a ball mill, add 40 mL of ethanol and 60 g of balls (large balls: medium balls: small balls = 2:5:3, mass ratio), ball mill at 200 rpm for 6 h, and then dry at 110 ° C for 12 h to obtain GDC / BYC7.

[0052] (2) Preparation of asymmetric membrane: 0.1 g commercial GDC powder, 1.5 g GDC / BYC7 mixture, and 0.1 g commercial GDC powder were pressed into a stainless steel mold (20 mm in diameter) in sequence and maintained at 187 MPa for 3 min using a powder tablet press. The obtained product was calcined in an alumina crucible at 1100 °C in an air atmosphere for 6 h, heating from room temperature (20-30 °C) to 1100 °C at a heating rate of 2 °C min. -1 After high-temperature calcination and natural cooling in the furnace, a GDC-GDC / BYC7-GDC membrane was obtained. The GDC layer was polished on one side using SiC paper (i.e., the GDC layer on one side was completely removed) to obtain an asymmetric membrane material of GDC / BYC7 (support layer)-GDC (permeation layer).

[0053] (3) Molten carbonate infiltration: A eutectic mixture of Li2CO3 and Na2CO3 with a molar ratio of 52 (Li2CO3): 48 (Na2CO3). The two substances were first ball milled in a 200 rpm ball mill for 6 h, then dried at 60 ° C for 12 h. The resulting mixed carbonate was melted again at 600 ° C for 2 h. After cooling, the carbonate was ground to obtain a submicron powder. 0.2 g of MC powder (molten carbonate) was placed on the infiltration layer (GDC) and heated at 1 ° C min-1 The heating rate is raised from room temperature (20-30 degrees Celsius) to 600°C and kept warm for 1 hour. MC will in situ penetrate into the gaps of GDC to form a dense membrane material.

[0054] Step 2, methane dry reforming catalyst is Ni / CeO2 catalyst, taking the final 1g catalyst as an example

[0055] Weigh 0.4955g Ni(NO3)2·6H2O and dissolve it in 10mL deionized water. After it is completely dissolved, add 0.9g CeO2 powder to the above dispersion and stir vigorously at room temperature of 20-30 degrees Celsius for 6h (300 revolutions per minute) to allow the CeO2 powder to fully absorb the impregnation solution. After reaching absorption equilibrium, the impregnation is completed, and then the solution is transferred to a 60℃ forced air drying oven. After it is completely dried, the obtained powder is ground and transferred to a muffle furnace. In an air atmosphere, the temperature is raised from room temperature of 20-30 degrees Celsius at a rate of 5 degrees Celsius per minute to 1000℃, and the mixture is kept warm and calcined for 1h. The mixture is naturally cooled to room temperature of 20-30 degrees Celsius with the furnace to obtain a catalyst precursor in the form of NiO / CeO2.

[0056] In step 3, the catalyst precursor obtained in step 2 and the CO2 separation membrane are combined by a granulation method, and the CO2 permeability and conversion rate are tested by gas chromatography in a simulated flue gas environment to evaluate the capture and conversion capabilities of the integrated catalytic system. The specific combination method is as follows:

[0057] Granulation method: Take the NiO / CeO2 catalyst precursor in step 2, press it into tablets at a pressure of 3MPa, hold it for 2 minutes, crush it into tablets, pass it through a 40-60 sieve, and obtain catalyst precursor particles with a certain strength after screening.

[0058] Before the test, 0.05 g of the prepared catalyst precursor particles were mixed with 0.35 g of quartz sand and loaded into a microtubular fixed-bed reactor. Before the reforming reaction, the precursor was heated to 600°C at a rate of 5°C per minute under air atmosphere. Then, a mixture of hydrogen and argon was introduced for reduction, with the volume percentage of hydrogen being 10% and the introduction rate of the mixed gas being 50 mL min. -1 , the reduction time is 3h.

[0059] like Figure 3As shown, a schematic diagram of the reaction device and gas circuit during the test of the present invention is shown, wherein the gas cylinders of carbon dioxide and nitrogen are connected to the air inlet pipe through their respective gas pipelines, and corresponding mass flow controllers are set in their respective gas pipelines to adjust the flow rates of carbon dioxide and nitrogen; the gas cylinders of methane and argon are connected to the purge air pipe through their respective gas pipelines, and corresponding mass flow controllers are set in their respective gas pipelines to adjust the flow rates of methane and argon. A temperature probe is set in the tubular furnace, and an integrated catalytic system is set between the first alumina tube and the second alumina tube. The GDC (permeation layer) corresponds to the first alumina tube, the air inlet pipe extends into the first alumina tube and is located above the permeation layer, below the permeation layer is the GDC / BYC7 (support layer), below the support layer is the catalyst layer, that is, the catalyst particles are arranged below the support layer, and the purge air pipe extends into the second alumina tube and is located below the catalyst layer. At this point, the CO2 / N2 mixture introduced through the inlet pipe passes through the integrated CO2 separation membrane, selective separation by the catalytic system, and in-situ reaction with the introduced CH4. An outlet pipe is then set up in the second alumina tube, and the product is introduced into a gas chromatograph to detect gas concentration and calculate CO2 permeability and conversion. Since the catalyst needs to be reduced before use, combined with the previous description of reduction, it is possible to consider using a mixture of hydrogen and argon to reduce the catalyst (located below the support layer). After the reduction is completed, the gas path is switched to methane and argon.

[0060] By attaching Figure 3 The apparatus shown was used to test the CO2 permeability: during heating and permeation measurement, CO2 (50 mL min -1 ) and N2 (50 mL·min -1 ), and the purge gas Ar (100 mL min -1 ), at this time no methane is provided as a raw material. The system starts collecting data after running stably at 600°C for 2 hours. Starting from 600°C, measurements are taken in increments of 50°C up to 800°C. Before data collection begins, the system is tested after stabilizing at the required temperature for 1 hour. For the data at each temperature, one point is measured every 15 minutes and the average value is taken. The composition of the purge gas is determined by a GC9790 II gas chromatograph equipped with a TCD detector, and the CO2 flux is corrected by the amount of N2 leakage in the chromatogram. The measured leakage N2 flux accounts for approximately 3-5% of the total carbon dioxide detected.

[0061]

[0062] Total CO2 permeability. N2 permeability (caused by physical leaks). Corrected CO2 permeability. CO2 concentration directly detected by chromatography. N2 concentration directly detected by chromatography. Ar : Flow rate of sweep gas Ar (unit controlled by mass flow meter). S: Permeation area of membrane (about 1.65 cm -2 ).

[0063] By attaching Figure 3 The device shown in the figure tests the conversion rate of methane dry reforming reaction: the CO2 permeation flow rate (permeation rate * membrane permeation area) obtained by the permeation test is matched with the CH4 flow rate of the same flow rate, and 50 mL min -1 The purge gas is used to test the conversion rate of the CO2 separation membrane combined with the catalyst, and the amount of unconsumed CO2 is measured by gas chromatograph. However, due to the side reactions such as RWGS reaction and methane cracking reaction CH4=C+2H2 that may occur when using Ni-based catalysts, the amount of CO2 consumed is uncertain. In order to solve this problem, the mass conservation of H and O species is utilized. First, the volume of H2O produced during the RWGS reaction can be calculated by H balance based on the CH4 consumed and the H2 concentration detected in the chromatogram. Therefore, the amount of CO2 consumed can be determined based on the O (H2O and CO) produced. The total CO2 permeability and methane dry reforming conversion rate are calculated by the following formula:

[0064]

[0065] Total CO2 permeability (mol·s-1). J CO2,unconsumed : Unconsumed CO2 outlet flow rate (mol·s-1). Consumed CH4 permeability (mol·s-1). The CH4 mass flow rate (mol·s-1) entering and leaving the system. The H2 and CO production rates are calculated as follows, and H2 / CO is calculated from them:

[0066]

[0067] The powder mass pressed in step 1 (2) of Example 1 was varied to obtain support layer and permeation layer membrane materials of varying thicknesses. Specifically, 0.3 g of GDC, 1.5 g of the 5C-GDC / BYC7 mixture, and 0.3 g of GDC were sequentially pressed into a stainless steel mold (20 mm diameter), resulting in an asymmetric membrane material having a GDC / BYC7 support layer thickness of 1000 μm and a GDC permeation layer thickness of 190 μm. This is referred to as Comparative Example 2.

[0068] The powder mass pressed in step (2) of Example 1 was varied to obtain support layer and permeation layer membrane materials of varying thicknesses. Specifically, 0.5 g of GDC, 1.5 g of the 5C-GDC / BYC7 mixture, and 0.5 g of GDC were sequentially pressed into a stainless steel mold (20 mm diameter), resulting in an asymmetric membrane material having a GDC / BYC7 support layer thickness of 1000 μm and a GDC permeation layer thickness of 286 μm. This is referred to as Comparative Example 3.

[0069] The powder mass pressed in step 1 (2) of Example 1 was varied to obtain support layer and permeation layer membrane materials of varying thicknesses. Specifically, 0.1 g of GDC, 1 g of the 5C-GDC / BYC7 mixture, and 0.1 g of GDC were sequentially pressed into a stainless steel mold (20 mm diameter) to obtain an asymmetric membrane material having a GDC / BYC7 support layer thickness of 750 μm and a GDC permeation layer thickness of 80 μm, referred to as Comparative Example 4.

[0070] The powder mass pressed in step 1 (2) of Example 1 was varied to obtain support layer and permeation layer membrane materials of varying thicknesses. Specifically, 0.5 g of GDC, 2 g of the 5C-GDC / BYC7 mixture, and 0.5 g of GDC were sequentially pressed into a stainless steel mold (20 mm diameter), resulting in an asymmetric membrane material having a GDC / BYC7 support layer thickness of 1500 μm and a GDC permeation layer thickness of 80 μm. This is referred to as Comparative Example 5.

[0071] The above examples and comparative examples were characterized by SEM. Figure 1 As shown, SEM photos of permeation layers (a, b, c) and support layers (d, e, f) of different thicknesses obtained according to the preparation methods of the embodiments and comparative examples of the present invention are shown, wherein the combination of (a) and (e) corresponds to the permeation layer and support layer prepared in Example 1, the combination of (b) and (e) corresponds to the permeation layer and support layer prepared in Example 2, the combination of (c) and (e) corresponds to the permeation layer and support layer prepared in Example 3, the combination of (a) and (d) corresponds to the permeation layer and support layer prepared in Example 4, and the combination of (a) and (f) corresponds to the permeation layer and support layer prepared in Example 5. The thickness of the support layer and permeation layer of all embodiments and comparative examples meets the sample preparation requirements and there are no cracks, gaps, etc. in the layer, which is conducive to reducing CO2 leakage.

[0072] High temperature penetration test results such as Figure 2As shown, the permeability comparison curves of the CO2 separation membranes of the present invention with different permeation layer and support layer thicknesses, wherein in (a), the corresponding relationship of the permeability curves is: when the permeation layer thickness is 80 μm, the support layer changes to 750 μm (Comparative Example 4), 1000 μm (Example 1), 1500 μm (Comparative Example 5); in (b), the corresponding relationship of the permeability curves is: when the support layer thickness is 1000 μm, the permeation layer changes to 80 μm (Example 1), 190 μm (Comparative Example 2), 286 μm (Comparative Example 3). It can be found from the curve that the asymmetric membrane material has the highest permeability when it is composed of a 1000 μm support layer and an 80 μm permeation layer (Example 1), reaching 1.12 mL·min -1 cm -2 . This is because membrane thickness is an important parameter for membrane separation performance. Within a certain range, the smaller the thickness of the membrane, the higher its CO2 permeability will be theoretically, which means that the amount of CO2 captured will be greater; however, if the membrane thickness is too thin, the mechanical strength of the membrane will decrease, making it easy to break in actual operation. Therefore, the membrane thickness needs to be able to ensure both a high CO2 permeability and sufficient mechanical strength. When the permeation layer is pressed into a film alone, it is easy for the membrane to break due to stress shrinkage during the high-temperature calcination process. Therefore, the present invention uses BYC7 to form a support layer to increase the mechanical strength of the membrane to ensure that it is not easily deformed at high temperatures, and GDC is added to ensure compatibility. At the same time, this support layer material can also reduce the thickness of the permeation layer to enhance the CO2 permeability. Such as Figure 2 As shown in (a), when the thickness of the permeation layer is fixed, the medium-thickness support layer shows the highest permeability. This is mainly because the support layer with a thickness of 750μm shrinks less after calcination (diameter after calcination: 19.24mm) and has a larger pore size, which causes part of the MC to penetrate into the support layer, increasing the bulk diffusion resistance of CO2; while the asymmetric membrane material with a support layer thickness of 1000μm will have a larger shrinkage degree after sintering (diameter after calcination: 19.08mm) due to the thicker support layer, and the pore size is relatively small, so the MC will not penetrate into the support layer, so the CO2 permeability will be larger; and when the support layer thickness is further increased to 1500μm, the excessive thickness of the support layer will make CO2 not easy to penetrate, resulting in a decrease in the overall permeability. The CO2 permeability of different permeation layer thicknesses was tested, as shown in the figure. Figure 2 As shown in (b), the permeability of CO2 decreases with the increase of the permeation layer thickness. Figure 1Morphology and Thickness Analysis: On the one hand, increasing the thickness of the permeable layer results in a less pronounced CO2 concentration gradient during transmission within the membrane. Furthermore, an excessively thick permeable layer, resulting from co-pressing and sintering, can increase CO2 mass transfer resistance. On the other hand, an excessively thin permeable layer can easily lead to CO2 leakage at the edges. In summary, CO2 permeation performance is optimal when the permeable layer is 80 μm thick and the support layer is 1000 μm thick. The integrated systems described below all utilize membranes of this thickness.

[0073] Example 2—The method of combining the catalyst and the membrane in step 3 of Example 1 was changed to screen printing, and the other preparation and testing conditions remained unchanged.

[0074] The steps of screen printing are as follows: 50 mg of catalyst powder was mixed with 1.5 g of PVB binder, 15 mL of ethanol was added and stirred evenly, and the slurry was evenly poured on one end of the screen. The screen was fixed on the printing table, and the CO2 separation membrane was laid flat underneath. The screen was scraped with a scraper at a constant speed of 60° (10 cm·s -1 ) with uniform pressure. Repeat the scraping process three times to ensure the catalyst slurry completely reaches the support layer. Slowly lift the screen to check the coating uniformity. Let it sit at room temperature for 10 minutes, then transfer it to an oven and dry it at 110°C for 1 hour. Finally, transfer it to a muffle furnace under air atmosphere and calcine it at 500°C for 2 hours to obtain a catalyst tightly bonded to the CO2 separation membrane.

[0075] Example 3—Change the catalyst and membrane bonding method in step 3 of Example 1 to the co-pressing method, and keep the other preparation and test conditions unchanged

[0076] Specific steps of the co-pressing method: Change the operation in step 1 (2) to press GDC, NiO / CeO2 precursor, 5C-GDC / BYC7 mixture, and GDC into a stainless steel mold (diameter 20 mm) in sequence, and use a powder tablet press to maintain the pressure at 187 MPa for 3 minutes. Use SiC paper to polish the GDC layer near the NiO / CeO2 precursor, and finally calcine it at 1100℃ in an alumina crucible for 6 hours at a heating rate of 2℃·min -1 , and a CO2 separation membrane containing a catalyst precursor is obtained.

[0077] Comparison of the catalytic performance of the three combined methods, such as Figure 4 As shown, at GHSV = 60000 mL g -1 ·h -1Performance curves obtained under space velocity conditions. Placing the catalyst pellets under the membrane has the highest CO2 conversion activity compared to other methods, with a CO2 conversion rate of up to 70% at 800°C, and shows significant differences from the other two combination methods. This is mainly because: placing the catalyst pellets under the separation membrane can maintain the original form of the catalyst, exposing more active sites compared to the other two combination methods; although screen printing is simple to prepare and the catalyst and membrane are more tightly bonded, it is inevitable that the slurry will stick to the screen or scraper during the slurry scraping process, resulting in an actual catalyst amount less than the other two methods. Moreover, since the slurry is mostly organic, it has a poisoning effect on the catalyst, resulting in an actual conversion rate of only 20%; the co-pressing method is to mix the catalyst precursor into the membrane material during the tableting stage. After subsequent infiltration and calcination, the most tightly bonded catalyst and membrane material can be obtained, but the actual measured conversion rate is less than 10%. This is because the active sites of the catalyst close to the permeation layer are buried, resulting in the inability to exert catalytic activity. Although screen printing and co-pressing methods have not yet achieved good conversion effects when combined with membranes, given that the two methods in the present invention can also achieve certain catalytic effects and the limitations of catalysts, slurries, and tableting techniques, subsequent research can be conducted to further improve the conversion rate.

[0078] Example 4

[0079] According to the method in Example 1, a CO2 separation membrane with a permeation layer thickness of 80 μm and a support layer thickness of 1000 μm was prepared, and 0.1 g of the granulated catalyst was mixed with 0.4 g of quartz sand and placed under the permeation membrane. Figure 3 The device shown, at CH4 / CO2 = 0.76 and GHSV = 60000 mL g -1 ·h -1 Under these conditions, the CO2 permeation rate (permeability * membrane permeation area) calculated from the permeability test was used to improve the conversion of both CH4 and CO2 by reducing the ratio of CH4 to CO2, while also reducing the impact of carbon deposits from excessive methane cracking on catalytic activity. The corresponding conversion rates were calculated using Equations 2.1 to 2.3, and the catalyst combining the CO2 separation membrane and pelletization method was subjected to a 210-hour stability test at 800°C.

[0080] As attached Figure 5 As shown in the figure, during the 210-hour stability test, the separation membrane and catalyst did not deactivate, the CH4 conversion rate remained at 100%, the CO2 conversion rate remained at around 90%, and the H2 / CO ratio was always close to 1; the CO2 permeability increased slightly and finally stabilized at 1.86 mL·min -1 cm -2 This shows that the integrated system has considerable stability under the test temperature and intake conditions. Figure 6The morphology of the CO2 separation membrane after the stability test was studied, and it was found that no obvious cracks, bending or other problems appeared after the test (a). However, small holes appeared in the permeation layer after the stability test (b), mainly because the molten carbonate lost to the support layer close to the permeation layer (c). Although some MC penetrated into the voids of the support layer, there was no decrease in the CO2 capture rate. This is mainly because there is a catalyst bed under the integrated system membrane, which causes the permeated CO2 to react quickly, resulting in a large concentration gradient difference of CO2 above and below the support layer membrane. Therefore, even if some of the holes are filled, it will not affect the CO2 capture rate. In addition, the SEM results of the support layer far away from the permeation layer (d) show that no obvious MC is observed in the voids, which further proves that even if a small amount of MC penetrates into the support layer in the presence of the catalyst, it will not have a significant impact on the CO2 permeation rate.

[0081] Adjustments to the preparation process according to the present invention can achieve the preparation of the catalyst and exhibit performance substantially consistent with the present invention. The above description of the present invention is illustrative, and it should be noted that any simple variation, modification, or equivalent substitution that can be made by a person skilled in the art without inventive effort without departing from the core of the present invention falls within the scope of protection of the present invention.

Claims

1. An integrated carbon dioxide separation membrane, characterized in that: It includes a permeation layer and a support layer, wherein: Molten carbonate permeates into the porous GDC to form a mixed oxygen ion-carbonate ion conductor membrane as the permeation layer. The GDC composition is Ce 0.9 Gd 0.1 O 1.95 , A support layer is set below the permeation layer. The support layer is GDC / BYC7. The BYC7 composition is (Bi 0.75 Y 0.25 ) 0.93 Ce 0.07 O 1.5±δ Defective metal oxides are prepared by weighing GDC and BYC7 powders in a mass ratio of GDC:BYC7 of (3-5):(1-2), adding carbon black and PVDF, ball milling and drying to obtain a GDC / BYC7 mixture, and calcining it at a high temperature of 1000-1200 degrees Celsius in an air atmosphere.

2. The integrated carbon dioxide separation membrane according to claim 1, characterized in that The molten carbonate is at least one of lithium carbonate, sodium carbonate, and potassium carbonate, preferably a eutectic mixture of Li2CO3 and Na2CO3, with a molar ratio of Li2CO3 to Na2CO3 of 52:48; the thickness of the permeation layer is 50 to 300 μm, preferably 50 to 100 μm; the thickness of the support layer is 500 to 1725 μm, preferably 800 to 1200 μm.

3. A method for preparing an integrated carbon dioxide separation membrane, characterized in that: Prepare according to the following steps: Step 1: Preparation of asymmetric membrane materials GDC powder, GDC / BYC7 mixture and GDC powder are placed in a mold in sequence. After the powder is pressed into tablets, the resulting product is placed in an air atmosphere and heated from room temperature (20-30 degrees Celsius) to 1000-1200 degrees Celsius for high-temperature calcination for 5-8 hours. The product is then naturally cooled to room temperature (20-30 degrees Celsius) to obtain a GDC-GDC / BYC7-GDC membrane. The GDC layer on one side is then ground off to obtain an asymmetric membrane material with a GDC / BYC7 support layer and a GDC permeation layer. BYC7 is composed of (Bi 0.75 Y 0.25 ) 0.93 Ce 0.07 O 1.5±δ Defective metal oxides, δ is an unavoidable defect in sintering preparation; according to its composition, bismuth The metal nitrates of bismuth, yttrium and cerium and citric acid are dissolved in a dilute nitric acid solution, and the molar ratio of citric acid to total metal ions (the sum of the three metal ions of bismuth, yttrium and cerium) is (1-2):

1. The water is evaporated in a constant temperature water bath at 60-80°C to obtain a gel, which is then heated in a heating mantle until spontaneous combustion to obtain a black fluffy solid. After grinding, the solid is heated from room temperature (20-30°C) to 500-800°C in an air atmosphere at a heating rate of 1-5°C / min and calcined at this temperature for 4-6 hours. The solid is then cooled in the furnace and ground to obtain BYC7 powder. GDC and BYC7 powders were weighed in a mass ratio of (3-5) GDC:BYC7:(1-2), carbon black was weighed in an amount of 5-20 wt% of the total mass of carbon black, GDC and BYC7, and PVDF was weighed in an amount of 20-25% of the mass of carbon black. The four were mixed and ball-milled and dried to obtain a GDC / BYC7 mixture; Step 2, Molten Carbonate Infiltration The molten carbonate is placed above the permeation layer, heated to 500-800 degrees Celsius and kept warm, so that the molten carbonate can penetrate into the GDC voids of the permeation layer in situ to form a dense membrane material.

4. The method for preparing an integrated carbon dioxide separation membrane according to claim 3, wherein: In step 1, the temperature is raised from room temperature (20-30 degrees Celsius) to 1000-1200 degrees Celsius at a rate of 1-5 degrees Celsius per minute for high-temperature calcination for 5-8 hours, preferably 6-8 hours. The thickness of the support layer and the permeation layer are adjusted according to the amount of GDC powder and the 5C-GDC / BYC7 mixture used. After tableting, a permeation layer with a thickness of 50-300 μm and a support layer with a thickness of 500-1725 μm are obtained. Preferably, the permeation layer has a thickness of 50-100 μm and the support layer has a thickness of 800-1200 μm.

5. The method for preparing an integrated carbon dioxide separation membrane according to claim 3, wherein: In step 1, water is evaporated in a constant temperature water bath at 60-80°C to obtain a gel, which is then heated in a heating mantle until spontaneous combustion to obtain a black fluffy solid. After grinding, the solid is heated from room temperature (20-30°C) to 700-800°C in an air atmosphere at a heating rate of 1-5°C / min and kept warm for calcination for 5-6 hours. The solid is then cooled and ground to obtain BYC7 powder. When ball milling carbon black, GDC and BYC7, 40 ml of ethanol and 60 g of balls are added, wherein the mass ratio of large balls: medium balls: small balls is 2:5:3, and the solid is ball milled at 200-400 rpm for 5-8 hours. The powder was dried in an oven at 100-120°C for 10-12 hours to obtain GDC / BYC7; the mass fraction of carbon black added was 5-10wt% of the total mass of the powder, and the amount of PVDF used was 20-22% of the mass of the carbon black; GDC powder, GDC / BYC7 mixture and GDC powder were pressed into a stainless steel mold in sequence, and a powder tablet press was used to maintain the pressure at 150-200 MPa for 1-3 minutes to form the powder into sheets; after obtaining the GDC-GDC / BYC7-GDC membrane, the GDC layer on one side was polished and removed using SiC paper to obtain an asymmetric membrane material.

6. The method for preparing an integrated carbon dioxide separation membrane according to claim 3, wherein: In step 2, the molten carbonate is at least one of lithium carbonate, sodium carbonate, and potassium carbonate, preferably a eutectic mixture of Li2CO3 and Na2CO3, with a molar ratio of Li2CO3 to Na2CO3 of 52:48; the molten carbonate is ball-milled in a ball mill at 200-300 rpm for 6-8 hours, and then dried at 60-80°C for 10-15 hours, preferably 10-12 hours, and the obtained ball-milled molten carbonate is melted at 500-800°C for 1-3 hours, and after cooling, the carbonate is ground to obtain a submicron powder; and the mixture is precipitated at room temperature of 20-30 degrees Celsius at a temperature of 1-5°C·min -1 The temperature is raised to 500-800°C at a heating rate of 100-200°C and kept warm for 1-3 hours, so that the molten carbonate can penetrate into the voids of the permeation layer GDC in situ to form a dense membrane material.

7. The catalytic system based on the integrated carbon dioxide separation membrane according to claim 1 or 2, characterized in that: The integrated carbon dioxide separation membrane is used as the main body, and a catalyst precursor for methane dry reforming is set on the supporting layer GDC / BYC7, which is first reduced with hydrogen when used subsequently.

8. The catalytic system based on the integrated carbon dioxide separation membrane according to claim 7, characterized in that: The catalyst precursors used for methane dry reforming are NiO / CeO2, NiO-LaAlO3 / Al2O3 or NiO-CeAlO3 / CeO2.

9. A method for preparing a catalytic system based on an integrated carbon dioxide separation membrane, characterized in that: The catalyst precursor is placed on the support layer GDC / BYC7 of the integrated carbon dioxide separation membrane by co-pressing, screen printing or pelletizing: (1) Granulation method: After the catalyst precursor is pressed into tablets, it is crushed into granules, sieved, and the catalyst precursor particles are placed under the support layer; (2) Screen printing method: Mix the catalyst precursor and the binder, stir evenly, and pour the slurry evenly on one end of the screen. Fix the screen on the printing table, lay the integrated carbon dioxide separation membrane flat underneath with its support layer facing upward, and use a scraper to scrape the screen at a constant speed and pressure. Repeat the scraping, slowly lift the screen, check the uniformity of the coating, let it stand at room temperature, then transfer it to an oven for drying, and finally calcine it at 300-500℃ for 1-3h. (3) Co-pressing method: GDC, catalyst precursor, GDC / BYC7 mixture, and GDC are pressed into a mold in sequence. After forming using a powder tablet press, the GDC on the side close to the catalyst precursor is ground off, and the resulting asymmetric membrane containing the catalyst precursor is calcined at 1000-1200°C for 5-8 hours.

10. Use of the integrated carbon dioxide separation membrane according to claim 1 or 2, or the catalytic system based on the integrated carbon dioxide separation membrane according to claim 7 or 8, in carbon dioxide capture and carbon dioxide capture-reforming.

Images