Preparation method of porous carbon carrier loaded carbon membrane and application of porous carbon carrier loaded carbon membrane in purification of low-concentration mixed hydrogen gas

Abstract

The application provides a preparation method of a porous carbon carrier loaded carbon membrane and application of the porous carbon carrier loaded carbon membrane in purification of a low-concentration mixed hydrogen gas. The preparation method comprises the following steps: taking formed biomass or formed phenolic resin as a base, coating an organic molecular reaction solution on the surface of the base, and obtaining the porous carbon loaded carbon membrane through copolymerization aging and carbonization. The porous carbon carrier has through mass transfer channels and screening channels, and shows a pre-concentration effect on low-concentration hydrogen. Meanwhile, a functional screening layer is grown on the surface, and the hydrogen can be further purified to high-purity hydrogen. The preparation method has expansibility, and the prepared porous carbon carrier loaded carbon membrane has wide application potential and market prospect in the fields of gas separation, catalytic new materials and integral electrodes.

Description

Technical Field

[0001] This invention belongs to the field of gas separation membrane technology, and relates to a method for preparing a porous carbon support-supported carbon membrane and its application in the purification of low-concentration mixed hydrogen gas. Background Technology

[0002] Hydrogen, as a renewable energy source, is widely used in ammonia synthesis, petroleum refining, semiconductor manufacturing, and fuel cell industries. Currently, hydrogen is mainly produced through fossil fuel production, industrial by-product hydrogen, and methanol or ammonia cracking. However, these methods typically yield low-concentration mixed hydrogen gases containing numerous impurities, which require further purification depending on the application. Therefore, the development of efficient and highly selective hydrogen separation technologies has attracted considerable interest. Compared to traditional physical and chemical adsorption, membrane separation technology offers advantages such as simple operation, low cost, and environmental friendliness.

[0003] Carbon membranes, as novel, efficient, and energy-saving inorganic separation membranes, possess advantages such as high specific surface area, high thermal stability, and renewability. Their suitable pore structure makes them particularly suitable for separating small-molecule gases in gas mixtures. The published Chinese patent CN116571098A describes the preparation of fiber carbon membranes by spinning casting solution followed by carbonization, achieving a hydrogen permeation rate as high as 2179 GPU. However, the hydrogen / nitrogen separation selectivity is low (<7.5), and the prepared carbon membrane lacks a support, making it prone to damage and performance degradation. Centeno et al. coated a porous carrier with a phenolic resin solution at a pore size of 20 nm, and the resulting carbon membrane exhibited molecular sieving properties. This process improved the separation selectivity of the carbon membrane but resulted in a loss of hydrogen permeation (J.Membr.Sci.2004,228:45-54.). Janice B. Hamm et al. reviewed the important role of porous supports in improving the mechanical strength of carbon membranes (Int. J. Hydrog. Energy, 2017, 42: 24830-24845.), but existing technologies do not address the separation performance of porous supports themselves. In the separation of low-concentration gases, especially the separation and purification of hydrogen in low-concentration mixed hydrogen gases, it is often necessary to couple separation processes such as pressure swing adsorption. It is difficult to achieve one-step purification of low-concentration hydrogen using a single technology. Summary of the Invention

[0004] To address the shortcomings of existing technologies, one objective of this invention is to provide a method for preparing a porous carbon support-supported carbon membrane. Another objective is to achieve hydrogen purification from low-concentration mixed hydrogen gas while simultaneously ensuring high hydrogen permeation and high separation selectivity. The porous carbon support of this invention uses porous carbon with molded biomass as a precursor or molded phenolic resin as a precursor. The membrane preparation process employs blade coating or spin coating. The carbonization atmosphere uses an inert gas atmosphere or a controlled-ratio reducing gas / inert gas mixture. Adjusting the carbonization atmosphere directly alters the pyrolysis mode of the membrane precursor and the molded biomass or molded phenolic resin, thereby controlling the pore size of the mesopores in the porous carbon support and achieving pre-purification of low-concentration hydrogen. Simultaneously, it promotes the formation and accumulation of carbon microcrystals in the carbon membrane, resulting in ultrapores for hydrogen purification. The invention has the following advantages: by utilizing the pre-purification function of porous carbon carrier, it can not only solve the problem of balancing permeation and selectivity, but also solve the difficulty of purifying low-concentration hydrogen to high concentration in one step using carbon membrane, thus saving costs and improving economic efficiency.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing a carbon membrane supported on a porous carbon support includes the following steps:

[0007] (1) Add the carbonyl-containing aromatic compound, the hydroxyl-containing aromatic compound, and the amino-containing aromatic compound sequentially to the alcohol-water mixed solvent;

[0008] (2) Place the solution prepared in step (1) into a sealed container, heat the sealed container to 60-150℃ and maintain it for 5-170h, then cool and remove the reaction solution.

[0009] (3) Apply the reaction liquid obtained in step (2) onto the surface of a material based on molded biomass or molded phenolic resin by scraping or spin coating.

[0010] (4) Place the composite material obtained in step (3) in an oven and heat it to 60-120℃ for copolymerization aging for 1-4 hours;

[0011] (5) The material obtained in step (4) is placed in a carbonization furnace and carbonized in an inert gas or a mixture of reducing gas and inert gas to obtain a porous carbon carrier loaded carbon membrane; the carbonization temperature is 500-1200℃ and the carbonization time is 1-5h.

[0012] In step (1), the carbonyl aromatic compound is selected from one or more of benzaldehyde, isophthalaldehyde, trimesoaldehyde and phenylacetaldehyde.

[0013] In step (1), the hydroxyl-containing aromatic compound is selected from one or more of resorcinol, phenol, pyrogallol, and salicylol.

[0014] In step (1), the amino-containing aromatic compound is selected from one or more of aniline, m-phenylenediamine and 1,3,5-tris(4-aminophenyl)benzene.

[0015] In step (1), the alcohol-water mixed solvent is a mixed solvent of ethanol and water, a mixed solvent of methanol and water, a mixed solvent of benzyl alcohol and water, or a mixed solvent of isopropanol and water.

[0016] In step (1), the molar ratio of carbonyl aromatic compounds: hydroxy aromatic compounds: amino compounds is (1-10):(1-10):(1-10); the volume ratio of alcohol to water is (1-500):(1-500).

[0017] In step (3), the substrate is a molded phenolic resin.

[0018] The pore size of the porous carbon support is concentrated in the range of 5.0-6.3 nm.

[0019] In step (3), the coating is applied using a scraping method.

[0020] In step (4), the oven temperature is 80-100℃; the copolymerization aging time is 2h.

[0021] In step (5), the volume ratio of reducing gas to inert gas in the mixed gas is 1:99-99:1.

[0022] In step (5), the inert atmosphere is preferably argon, and the mixture of reducing gas and inert gas is a mixture of hydrogen and argon.

[0023] This invention also provides an application of porous carbon support loaded carbon membrane in hydrogen purification in low-concentration mixed hydrogen gas.

[0024] The beneficial effects of this invention are as follows: This invention uses molded biomass or molded phenolic resin as a substrate, coats the substrate surface with an organic molecular reaction liquid, and obtains a porous carbon-supported carbon membrane through copolymerization aging and carbonization. This porous carbon support has interconnected mass transfer channels and sieving channels, and functional sieve layers are grown on its surface. Specifically, taking molded phenolic resin as a substrate as an example, utilizing the hydrogen bonding between the abundant oxygen-containing functional groups on the surface of the phenolic resin and the organic molecules (carbon membrane precursor), a dense polymer material is grown on top of the phenolic resin through copolymerization aging. The porous carbon-supported carbon membrane is then directly prepared through a subsequent carbonization process. This porous carbon support retains the framework structure of phenolic resin-type carbon, has interconnected mass transfer channels and sieving channels, exhibits a pre-concentration effect for low-concentration hydrogen, and the functional sieve layers grown on its surface can further purify hydrogen to high-purity hydrogen. The preparation method provided by this invention is scalable, and the prepared porous carbon support-supported carbon membrane has broad application potential and market prospects in gas separation, new catalytic materials, and monolithic electrodes. Attached Figure Description

[0025] Figure 1 This is a scanning electron microscope image of the porous carbon-supported carbon membrane prepared in Example 1 of the present invention.

[0026] Figure 2 This is a scanning electron microscope image of the phenolic resin-derived carbon from Comparative Example 1 of the present invention.

[0027] Figure 3 This is the pore size distribution of the phenolic resin-derived carbon from Comparative Example 1 of the present invention. Detailed Implementation

[0028] To better understand the present invention, the following detailed description is provided in conjunction with embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0029] The preparation process of polymer-supported polymer materials is as follows:

[0030] The phenolic resin used in the examples was prepared according to the method described in CN101723354A.

[0031] Example 1.1

[0032] Weigh resorcinol, aniline, and benzaldehyde in a molar ratio of 10:1:10 and add them to 5 mL of a mixed solvent of benzyl alcohol and water (4:1) and stir until dissolved. Transfer the solution to a sealed container, heat to 90 °C and react for 30 h. After the reaction is complete, take it out for later use and name the sample BPF-1.

[0033] Example 1.2

[0034] Weigh out phenol, m-phenylenediamine, and m-phenylenedialdehyde in a molar ratio of 1:10:1 and add them to 5 mL of a mixed solvent of methanol and water (10:1) and stir until dissolved. Transfer the solution to a sealed container and heat to 60 °C for 170 h. After the reaction is complete, take it out for later use and name the sample BPF-2.

[0035] Example 1.3

[0036] Weigh 1,3,5-tris(4-amino)benzene and pyromellitic aldehyde in a molar ratio of 1:2:1 and add them to 5 mL of a mixed solvent of ethanol and water (1:500) and stir until dissolved. Transfer the solution to a sealed container and heat to 150 °C for 5 h. After the reaction is complete, take it out for later use and name the sample BPF-3.

[0037] Example 1.4

[0038] Weigh out salicyl alcohol, aniline, and phenylacetaldehyde in a molar ratio of 1:4:1 and add them to 5 mL of a mixed solvent of isopropanol and water (500:1) and stir until dissolved. Transfer the solution to a sealed container and heat to 120 °C for 170 h. After the reaction is complete, take it out for later use and name the sample BPF-4.

[0039] The preparation process of porous carbon-supported carbon membranes is as follows:

[0040] Example 2.1

[0041] The prepared polymer material BPF-1 was coated onto molded phenolic resin using a blade coating method. The blade height was 50 μm and the blade speed was 2 cm / s. After two coats, the prepared composite material was placed in an oven at 90℃ for copolymerization aging for 2 hours. It was then placed in a ceramic boat in a carbonization furnace and purged with an argon atmosphere or a hydrogen / argon mixture at a ratio of 99:1 (vol%) at a temperature of 0.1℃·min⁻¹. -1 The heating rate was increased from room temperature to 700℃ or 800℃ and held for 2 hours, and the results were denoted as CBPF-1-700, CBPF-1-700-H2, CBPF-1-800, and CBPF-1-800-H2, respectively, to prepare porous carbon-supported carbon membranes. Figure 1 The image shown is a scanning electron microscope (SEM) image of the CBPF-1-800. The prepared porous carbon support-loaded carbon film has a dense sieve layer; the porous carbon support is a porous material, and there is no delamination or cracking between the support and the sieve layer, indicating that the polymer material can grow on the surface of the molded polymer due to hydrogen bonding.

[0042] Example 2.2

[0043] The prepared polymer material BPF-2 was coated onto molded phenolic resin using a blade coating method. The blade height was 50 μm and the blade speed was 2 cm / s. After two coats, the prepared composite material was placed in an oven at 100℃ for copolymerization aging for 2 hours. Then, it was placed in a ceramic boat in a carbonization furnace and purged with a gas mixture of hydrogen and argon at a ratio of 99:1 (vol%) at 5℃·min. -1 The temperature was increased from room temperature to 800℃ or 1200℃ and held for 5 hours to prepare porous carbon support-supported carbon membranes. The samples were named CBPF-2-800-H2 and CBPF-2-1200-H2.

[0044] Example 2.3

[0045] The prepared polymer material BPF-3 was coated onto the molded phenolic resin using a blade coating method. The blade height was 50 μm and the blade speed was 2 cm / s. After two coats, the prepared composite material was placed in an oven at 80℃ for copolymerization aging for 2 hours. The composite material was then coated onto the molded phenolic resin using a blade coating method and placed in a ceramic boat in a carbonization furnace. Under a gas purging system of hydrogen / argon mixed in a ratio of 5:95 (vol%), the mixture was heated at 1℃·min. -1 The temperature was increased from room temperature to 1200℃ and held for 1 hour to prepare a porous carbon support-supported carbon membrane. The sample was named CBPF-3-1200-H2.

[0046] Example 2.4

[0047] The prepared polymer material BPF-4 was coated onto the molded phenolic resin using a blade coating method. The blade height was 50 μm and the blade speed was 2 cm / s. After two coats, the prepared composite material was placed in an oven at 100℃ for copolymerization aging for 2 hours. Then, it was placed in a ceramic boat in a carbonization furnace and carbonized at 0.1℃·min under an argon atmosphere. -1 The temperature was increased from room temperature to 800℃ and held for 2 hours to prepare a porous carbon support-supported carbon membrane. The sample was named CBPF-4-800.

[0048] Example 3 (Single-component permeation performance of porous carbon-supported carbon membrane)

[0049] Taking Example 2 as an example, the permeation performance of the porous carbon-supported carbon membrane with sieving function to single-component gases was tested after pyrolysis treatment at different carbonization temperatures:

[0050] Porous carbon-supported carbon membranes were degassed at 250℃ for 12 h; the permeation rates of different gas molecules at 1 bar and 298 K were tested using a membrane testing device. The sample numbers and single-component gas permeation test results are shown in Table 1.

[0051] Table 1. Comparison of gas permeation test results of porous carbon-supported carbon membranes and their corresponding single-component membranes in Example 3.

[0052]

[0053] Example 4 (Dynamic separation performance of porous carbon-supported carbon membranes)

[0054] This invention provides an application of the porous carbon-supported carbon membrane for purifying hydrogen in a low-to-medium concentration mixed hydrogen gas. The application process is as follows: the temperature of the membrane module carrying the porous carbon-supported carbon membrane is controlled at 243-373℃. The mixed hydrogen gas is introduced into one side of the membrane module, and argon gas of the same volume fraction is introduced into the other side. A pressure difference of 0.1-3.0 MPa is used as the driving force to allow the mixed gas to permeate through the porous carbon-supported carbon membrane. After dilution with argon gas, the components are analyzed by chromatography to obtain hydrogen of the corresponding purity.

[0055] Table 2. Evaluation results of the separation performance of porous carbon-supported carbon membranes prepared in each embodiment.

[0056]

[0057] Comparative Example 1

[0058] The molded phenolic resin from Example 1 was taken out separately and carbonized under the conditions of Example 2.2 at a carbonization temperature of 800°C to obtain a porous carbon support with mesopores. Scanning electron microscopy was used to analyze the carbon. Figure 2 As shown, the aperture distribution is as follows Figure 3 As shown, this is Comparative Example 1. Then, a low-concentration hydrogen separation test was performed according to the test conditions in Example 4, and the calculated hydrogen permeation was 450 GPU, with a hydrogen / methane separation selectivity of 4.8. The phenolic resin-based carbon without sieve separation showed increased hydrogen permeation but lower selectivity.

[0059] The above description is merely a specific implementation example of this invention patent; however, the technical features of this invention patent are not limited thereto. It should be noted that, for those skilled in the art, various improvements and modifications can be made without departing from the principles and technical features of this invention, and all such changes, improvements, or modifications are covered within the protection scope of this invention patent.

Claims

1. A method for preparing a carbon membrane supported on a porous carbon carrier, characterized in that: Includes the following steps: (1) Add the carbonyl-containing aromatic compound, the hydroxyl-containing aromatic compound, and the amino-containing aromatic compound sequentially to the alcohol-water mixed solvent; (2) Place the solution prepared in step (1) in a sealed container, heat the sealed container to 60-150 ℃ and keep it for 5-170 h, then cool and take out the reaction solution. (3) Apply the reaction solution obtained in step (2) to the surface of a material based on molded biomass or molded phenolic resin by means of scraping or spin coating. (4) Place the composite material obtained in step (3) in an oven and heat it to 60-120 ℃ for copolymerization aging for 1-4 h; (5) Place the material obtained in step (4) in a carbonization furnace and carbonize it in an inert gas or a mixture of reducing gas and inert gas to obtain a porous carbon carrier loaded carbon membrane; the carbonization temperature is 500-1200 ℃ and the carbonization time is 1-5 h. In step (1), the molar ratio of carbonyl aromatic compound: hydroxyl aromatic compound: amino aromatic compound is (1-10):(1-10):(1-10); The volume ratio of alcohol to water is (1-500):(1-500); In step (1), the carbonyl-containing aromatic compound is selected from one or more of benzaldehyde, isophthalaldehyde, pyromellitic aldehyde, and phenylacetaldehyde; the hydroxyl-containing aromatic compound is selected from one or more of resorcinol, phenol, pyromellitic phloroglucinol, and salicylol; and the amino-containing aromatic compound is selected from one or more of aniline, m-phenylenediamine, and 1,3,5-tris(4-aminophenyl)benzene. The pore size of the porous carbon support is concentrated in the range of 5.0-6.3 nm; The porous carbon support loaded carbon membrane is used for hydrogen purification in low-concentration mixed hydrogen gas.

2. The method for preparing a porous carbon support-supported carbon membrane as described in claim 1, characterized in that: In step (1), the alcohol-water mixed solvent is a mixed solvent of ethanol and water, a mixed solvent of methanol and water, a mixed solvent of benzyl alcohol and water, or a mixed solvent of isopropanol and water.

3. The method for preparing a porous carbon support-supported carbon membrane as described in claim 1, characterized in that: In step (5), the volume ratio of reducing gas to inert gas in the mixed gas is 1:99-99:

1.

4. The application of a porous carbon support-supported carbon membrane obtained by the preparation method as described in claim 1 in hydrogen purification in low-concentration mixed hydrogen gas.

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