Preparation of coal-derived humic acid porous material and its application in separation and concentration of coal-bed gas

Abstract

The present application relates to a kind of porous materials prepared using coal-derived humic acid and a method for separating and concentrating methane in coal-bed gas by adsorption separation process.The present application uses coal-derived humic acid as raw material, and prepares coal-derived humic acid ultra-microporous porous material with concentrated pore size distribution by hydrothermal reaction and high-temperature activation process.Compared with prior art, the method of the present application has the advantages of cheap and readily available raw materials, simple preparation process, green and environmentally friendly process, and concentrated micropore size distribution of product. When the coal-derived humic acid porous material provided by the present application is applied to the separation and concentration of coal-bed gas, it has high adsorption capacity and excellent adsorption selectivity.

Description

Technical Field

[0001] This invention belongs to the field of gas separation and purification technology, specifically relating to a porous material prepared using coal-derived humic acid and a method for separating and concentrating methane in coalbed methane through an adsorption separation process. Background Technology

[0002] Adsorption separation is based on the differences in the adsorption capacity of adsorbents for different components. By changing pressure or temperature, specific components can be selectively separated to achieve the purpose of separating mixed gases and purifying single-component gases. Adsorption separation is considered a highly efficient and low-energy separation method due to its advantages of easy adsorbent regeneration, low energy consumption, simple operation, and ability to achieve high separation coefficients. The selection and properties of the chosen adsorbent are crucial to the efficiency of the separation process. Based on the adsorbent regeneration method, the corresponding cyclic adsorption processes mainly include temperature swing adsorption (TSA), pressure swing adsorption (PSA), vacuum adsorption (VSA), and inert gas purification cycles. Developing highly efficient adsorbents is a prerequisite for the widespread application of adsorption separation technology. In-depth design and research of highly efficient adsorbents are beneficial for further optimizing process routes, thereby developing more competitive adsorption separation technologies.

[0003] Coalbed methane (CBM) is an unconventional natural gas stored in underground coal seams, with CH4 as its main component. In recent years, the rapid development of unconventional natural gas, represented by low-enriched CBM (extracted CBM), low-saturation natural gas, and shale gas, has attracted global attention. These unconventional natural gas sources serve as an effective supplement to natural gas, significantly alleviating my country's dependence on imported natural gas. However, unconventional natural gas contains a large amount of impurities such as nitrogen during extraction, and the presence of CO2 and N2 significantly reduces the combustion efficiency of CH4. Therefore, achieving effective enrichment of methane in low-enriched CBM is particularly important.

[0004] Currently, most commonly used adsorbents are made of porous organic polymer materials. For example, Chinese patent CN103275286 B provides a method for preparing a porous organic polymer material for selective adsorption and separation. This polymer material is a porous organic polymer obtained by the condensation reaction of melamine and 2,4,6-trihydroxyisophthalaldehyde. This organic porous polymer material exhibits strong adsorption performance for carbon dioxide under normal pressure conditions from 273K to 298K, but it hardly adsorbs methane and nitrogen. Therefore, it cannot achieve effective separation of CH4 / N2 mixed gases from low-concentration coalbed methane.

[0005] For example, Chinese patent CN 104399353 B provides a method and apparatus for separating methane, carbon dioxide, nitrogen, or hydrogen into multiple components. It uses flexible materials TUTCH-1 or TUTCH-2 as adsorbents and achieves the separation of CO2, N2, and H2 by controlling the temperature and pressure conditions within the separation equipment. Porous polyethylene fiber elastic buffer layers are provided on both the front and rear sides of the first and second adsorption beds of the separation equipment to ensure stable gas flow and unobstructed gas passage. Using this separation device, almost all methane in the feed gas enters the methane-rich product gas, while simultaneously removing all CO2 and N2. The drawbacks of this patented method and apparatus are that the preparation of flexible materials TUTCH-1 and TUTCH-2 requires the use of various organic solvents such as copper nitrate, copper tetrafluoroborate, 2,5-dihydroxybenzoic acid, and 4,4'-bipyridine ethanol solution. The raw materials are not easy to obtain and are relatively expensive. Furthermore, the preparation process of flexible materials TUTCH-1 and TUTCH-2 has special process requirements for the mass ratio of raw materials, temperature control, the airtightness of the apparatus, and the washing and drying of the products, making it difficult to achieve industrial-scale promotion and application.

[0006] Chinese patent CN 114053996 B discloses a one-piece molded nitrogen-containing block porous carbon material, its preparation method, and its application. The preparation method of the porous carbon material includes: step 1, preparation of a precursor; step 2, activation-carbonization treatment. This method uses melamine-foamed sponge as a nitrogen source, which also serves as the carbon support framework of the block. Glucose is added to the framework as a secondary carbon source, achieving carbonization-activation of the porous carbon in one step. The prepared active porous carbon has high microporosity and high nitrogen content, making it suitable for CO2 adsorption or CO2 / CH4 separation. However, according to the adsorption effect data described in its specific embodiments, this one-piece molded nitrogen-containing block porous carbon material has a high N element content. N element can provide a large number of Lewis basic sites, which is beneficial for the adsorption of CO2 (acidic gas molecules), but has no significant effect on the separation of CH4 / N2 in low-concentration coalbed methane.

[0007] Chinese patent CN 111889078 A discloses a composite material for separating CH4 gas. This type of composite material combines MOF materials with porous polymer materials polyacrylate microspheres (PGT) and polyacrylamide microspheres (PAM). It retains the gas adsorption and separation capabilities of metal-organic frameworks (MOFs) while also exhibiting better hydrothermal stability and wear resistance. However, the composite material suffers from a cumbersome preparation process for the porous polymer microspheres (polyacrylate microspheres (PGT) and polyacrylamide microspheres (PAM)). The preparation process requires the initial preparation of various mixed solvents, including an aqueous phase, an oil phase, and a third phase. Raw materials and reagents include tert-butyl methacrylate (TBMA), glycidyl methacrylate (GMA), trimethylolpropane triacrylate (TMPTA), acrylamide (AM), N,N-methylenebisacrylamide (MBAM), toluene, cyclohexane, carbon tetrachloride, and other reagents such as emulsifiers, oxidants, initiators, dispersants, and reducing agents. This results in high production costs and makes it unsuitable for large-scale industrial application. Summary of the Invention

[0008] Existing porous materials cannot effectively separate CH4 / N2 mixed gases from low-concentration coalbed methane. While some porous materials can separate CO2, N2, and H2 from coalbed methane, they require specialized separation equipment and materials. The preparation of these materials requires various organic solvents, the raw materials are difficult to obtain and expensive, and the preparation process involves special process requirements, making industrial application difficult. This invention adopts a green and environmentally friendly new process to prepare a novel coal-derived humic acid porous material using humic acid extracted from low-rank coal. This material is then applied to the separation and purification of coalbed methane, thereby efficiently enriching methane from low-concentration coalbed methane.

[0009] To achieve the above objectives, the present invention adopts the following technical solution.

[0010] The coal-derived humic acid porous material of the present invention includes the following steps: preparing a precursor of the coal-derived humic acid porous material by hydrothermal reaction of coal-derived humic acid and an alkaline activator; and preparing the coal-derived humic acid porous material by high-temperature treatment of the precursor under an inert atmosphere.

[0011] The porous structure of the coal-derived humic acid material of the present invention is mainly composed of ultramicropores, with pore sizes concentrated in the range of 0.5 nm to 0.6 nm.

[0012] The coal-derived humic acid porous material of the present invention is prepared by the following method:

[0013] 1) Mix the coal-derived humic acid with an appropriate amount of potassium hydroxide or sodium hydroxide powder, add deionized water, stir until the mixture is uniform, and then carry out a hydrothermal reaction at a temperature of 160℃-180℃. After the reaction is completed, let it stand, cool to room temperature, and dry the product to obtain the precursor of the coal-derived humic acid porous material.

[0014] 2) The precursor is transferred to a tube furnace and carbonized at a high temperature of 600℃-800℃ under an inert atmosphere. After carbonization, the temperature is lowered to room temperature, the solid material is taken out, and after acid washing, filtration and drying, the coal-derived humic acid porous material is obtained.

[0015] Preferably, in step 1), the mass ratio of the alkaline activator to the coal-derived humic acid is 0.1:1 to 1:1.

[0016] Preferably, the alkaline activator is potassium hydroxide or sodium hydroxide.

[0017] Preferably, in step 2), the temperature for the hydrothermal reaction of the mixture is 140℃-200℃, and the reaction time is 8-10 hours. More preferably, in step 1), the temperature for the hydrothermal reaction of the mixture is 160℃, and the reaction time is 8 hours.

[0018] The porous coal-derived humic acid material of the present invention is suitable for the field of coalbed methane separation and purification, especially for the separation and concentration of CH4 / N2 mixture in coalbed methane. The optimal operating conditions are a temperature of 0℃-30℃ and a pressure of 0.1MPa-1MPa.

[0019] Compared with existing porous materials and their preparation methods, the coal-derived humic acid porous material provided by this invention has the following advantages.

[0020] (1) The method of the present invention uses coal-derived humic acid as raw material and prepares coal-derived humic acid porous materials through hydrothermal reaction and high-temperature activation process. Compared with other preparation methods of the same carbon porous materials, it has the advantages of requiring less activation alkali and concentrated micropore size distribution of the product. Compared with other existing preparation methods of porous materials prepared from other raw materials, it also has the advantages of cheap and readily available raw materials, simple preparation process, green and environmentally friendly preparation process, and high product yield.

[0021] (2) The porous coal-derived humic acid material prepared by the method of the present invention has pores that are mainly ultramicropores with a pore size distribution concentrated in an extremely narrow range of 0.5 nm to 0.6 nm. This pore size distribution can improve the intermolecular forces of the adsorbent for methane nitrogen, thereby improving the CH4 / N2 separation performance. In the embodiments of the present invention, BET and adsorption test data show that, under ambient pressure and an ambient temperature of 25°C, the CH4 adsorption capacity of the porous material of the present invention is as high as 21.9 cm³. 3 / g, the CH4 / N2 selectivity ratio is CH4 / N2=6.1; while under ambient conditions of normal pressure and 0℃, the CH4 adsorption capacity is as high as 31.3cm³. 3 The CH4 / N2 selectivity ratio of CH4 / N2 is 6.30, indicating that the coal-derived humic acid porous material of the present invention has high adsorption capacity and excellent adsorption selectivity.

[0022] (3) The coal-derived humic acid-based porous material prepared by the method of the present invention has the advantages of wide availability of raw materials, well-developed pores and high stability compared with other adsorbents such as MOFs and molecular sieves. It can also broaden the utilization channels of low-rank coal for extracting coal-derived humic acid while achieving methane enrichment, thereby improving the economic utilization efficiency of low-rank coal. Attached Figure Description

[0023] Figure 1 The BET characterization is of the HACs-1 porous material prepared in Example 1.

[0024] Figure 2 This is a pore size analysis of the HACs-1 porous material prepared in Example 1.

[0025] Figure 3 This describes the adsorption of methane and nitrogen by the HACs-1 porous material prepared in Example 1 under conditions of 298 K and 100 kPa.

[0026] Figure 4 This describes the adsorption of methane and nitrogen by the HACs-1 porous material prepared in Example 1 under conditions of 273 K and 100 kPa.

[0027] Figure 5 The adsorption selectivity of the HACs-1 porous material prepared in Example 1 for CH4 / N2 mixed gas at 298K and 273K is calculated based on IAST theory. Detailed Implementation

[0028] The specific implementation of the technical solution of the present invention will be further illustrated below through specific embodiments.

[0029]

Example 1

[0030] S1. Preparation of porous materials

[0031] 4g of coal-derived humic acid and 0.4g of KOH solid were weighed and dispersed in 50mL of aqueous solution and stirred for 30 minutes. The mixture was then transferred to a 100mL hydrothermal reactor and hydrothermally reacted at 160℃ for 8 hours. The mixture after hydrothermal reaction was dried to obtain the HACs material precursor. The precursor was activated in a tube furnace under a nitrogen atmosphere at a rate of 5℃ / min to a target temperature of 700℃ for 2 hours. After cooling to room temperature, the activated material was dispersed in 50mL of 1mol / L HCl solution and placed at 80℃ for 1 hour, followed by rinsing with deionized water until the pH reached neutral. After vacuum drying at 80℃ for 12 hours, a porous material was obtained, labeled HACs-1.

[0032] S2, Characterization of porous material structure

[0033] Approximately 100 mg of porous material was weighed and degassed at 150 °C for 8 hours. Adsorption was then performed using a Micromeritics ASPA 2460 physical adsorption analyzer at 77 K with N2 as the gas probe, yielding its N2 adsorption curve. Figure 1 According to the definition and classification of the International Union of Pure and Applied Chemistry (IUPAC) in 1985, pore width is the pore diameter (for cylindrical pores) or the distance between two opposing pore walls (for fissure pores). Specifically, it is defined as: (i) micropores are pores with an internal pore width less than 2 nm; (ii) mesopores are pores with a width between 2 nm and 50 nm; and (iii) macropores are pores with a pore width greater than 50 nm. In 2015, IUPAC further subdivided and supplemented the pore size classification, namely: (iv) nanopores: including micropores, mesopores, and macropores, but with an upper limit of only 100 nm; (v) ultramicropores: narrower micropores with a pore width less than 0.7 nm; and (vi) supermicropores: wider micropores with a pore width greater than 0.7 nm. Figure 1 The adsorption curve conforms to the characteristics of Type I curves in the IUPAC classification, indicating that the material contains a large number of micropores.

[0034] The specific surface area of ​​the HACs-1 porous material was measured to be 387.78 m². 2 / g, the microporous specific surface area is 303.09m². 2 The total pore volume is 0.134 cm³ / g. 3 / g of which the micropore volume is 0.199cm³ 3 / g. The pore size distribution was obtained using the NLDFT model derived from the built-in analysis software of the testing software, as shown below. Figure 2 As shown, the micropore size of HACs-1 is concentrated in the ultramicropore range of 0.5-0.6 nm.

[0035] S3, Performance Testing of Porous Material Products

[0036] The static adsorption selectivity of CH4 and N2 at 0℃ and 25℃ was tested using a Micromeritics ASPA 2460 physical adsorption analyzer under ambient pressure. The test method was as follows: approximately 100 mg of HACs-1 was weighed, degassed at 150℃ for 8 h, and the gas adsorption capacity at different equilibrium pressures was measured using the Micromeritics ASPA 2460 physical adsorption analyzer to obtain adsorption isotherms at different temperatures. Figure 3 and Figure 4 Then, using the IAST model, the static adsorption selectivity of HACs-1 material for CH4 / N2 at 0℃ and 25℃ was calculated. The calculation results are as follows: Figure 5 .Depend on Figure 5 It can be seen that at normal pressure and 25℃, the CH4 adsorption capacity of HACs-1 is as high as 21.94 cm⁻¹. 3 The CH4 / N2 selectivity was as high as 6.12 / g. At ambient pressure and 0℃, the CH4 adsorption capacity reached as high as 31.30 cm⁻¹. 3 The CH4 / N2 selectivity of HACs-1 is as high as 6.30 / g, indicating that the coal-derived humic acid porous material provided by this invention has high adsorption capacity and excellent adsorption selectivity.

[0037]

Example 2

[0038] 4 g of coal-derived humic acid and 0.4 g of KOH solid were weighed and dispersed in 50 mL of aqueous solution and stirred for 30 minutes. The mixture was then transferred to a 100 mL hydrothermal reactor and hydrothermally reacted at 160 °C for 8 hours. The mixture after hydrothermal reaction was dried to obtain the HACs material precursor. The precursor was activated in a tube furnace under a nitrogen atmosphere at a rate of 5 °C / min to a target temperature of 600 °C for 2 hours. After cooling to room temperature, the activated material was dispersed in 50 mL of 1 mol / L HCl solution and placed at 80 °C for 1 hour. It was then rinsed with deionized water until the pH reached neutral. After vacuum drying at 80 °C for 12 hours, the resulting coal-derived humic acid-based porous material was obtained and labeled as HACs-2.

[0039] The structural characterization method for the HACs-2 porous material is described in Example 1. The specific surface area of ​​the HACs-2 porous material was measured to be 38.60 m². 2 / g, with a microporous specific surface area of ​​24.72m². 2 / g, total pore volume is 0.0165cm³ 3 / g of which the micropore volume is 0.0115cm³ 3 / g. The micropore size of HACs-2 was found to be concentrated in the ultramicropore range of 0.5-0.6 nm using the NLDFT model measured by the built-in analysis software of the testing software.

[0040] The product performance testing method for HACs-2 porous materials is described in Example 1. The static adsorption selectivity test results of this material on a mixture of CH4 and N2 at 25°C are shown in Table 1.

[0041]

Example 3

[0042] 4g of coal-derived humic acid and 0.4g of KOH solid were weighed and dispersed in 50mL of aqueous solution and stirred for 30 minutes. The mixture was then transferred to a 100mL hydrothermal reactor and hydrothermally reacted at 160℃ for 8 hours. The mixture after hydrothermal reaction was dried to obtain the HACs material precursor. The precursor was activated in a tube furnace under a nitrogen atmosphere at a rate of 5℃ / min to a target temperature of 800℃ for 2 hours. After cooling to room temperature, the activated material was dispersed in 50mL of 1mol / L HCl solution and placed at 80℃ for 1 hour, followed by rinsing with deionized water until the pH reached neutral. After vacuum drying at 80℃ for 12 hours, the resulting coal-derived humic acid-based porous material was obtained and labeled HACs-3.

[0043] The structural characterization method for the HACs-3 porous material is described in Example 1. The specific surface area of ​​the HACs-3 porous material was measured to be 390.10 m². 2 / g, with a microporous specific surface area of ​​239.56m². 2 / g, total pore volume is 0.423cm³ 3 / g of which has a micropore volume of 0.093cm³ 3 / g. The micropore size of HACs-3 was found to be concentrated in the ultramicropore range of 0.5-0.6 nm using the NLDFT model measured by the analysis software built into the testing software.

[0044] The product performance testing method for HACs-3 porous materials is described in Example 1. The static adsorption selectivity test results of this material on a mixture of CH4 and N2 at 25°C are shown in Table 1.

[0045]

Example 4

[0046] 4g of coal-derived humic acid and 2g of KOH solid were weighed and dispersed in 50mL of aqueous solution and stirred for 30 minutes. The mixture was then transferred to a 100mL hydrothermal reactor and hydrothermally reacted at 160℃ for 8 hours. The mixture after hydrothermal reaction was dried to obtain the HACs material precursor. The precursor was activated in a tube furnace under nitrogen atmosphere at a rate of 5℃ / min to a target temperature of 600℃ for 2 hours. After cooling to room temperature, the activated material was dispersed in 50mL of 1mol / L HCl solution and placed at 80℃ for 1 hour, followed by rinsing with deionized water until the pH reached neutral. After vacuum drying at 80℃ for 12 hours, the resulting coal-derived humic acid-based porous material was obtained and labeled HACs-4.

[0047] The structural characterization method for the HACs-4 porous material is described in Example 1. The specific surface area of ​​the HACs-4 porous material was measured to be 686.33 m². 2 / g, with a microporous specific surface area of ​​430.09m². 2 / g, total pore volume is 0.233cm³ 3 / g of which has a micropore volume of 0.175cm³ 3 / g. The micropore size of HACs-4 was found to be concentrated in the ultramicropore range of 0.5-0.6 nm using the NLDFT model measured by the built-in analysis software of the testing software.

[0048] The product performance testing method for HACs-4 porous material is described in Example 1. The static adsorption selectivity test results of this material on a mixture of CH4 and N2 at 25°C are shown in Table 1.

[0049]

Example 5

[0050] 4g of coal-derived humic acid and 2g of KOH solid were weighed and dispersed in 50mL of aqueous solution and stirred for 30 minutes. The mixture was then transferred to a 100mL hydrothermal reactor and hydrothermally reacted at 160℃ for 8 hours. The mixture after hydrothermal reaction was dried to obtain the HACs material precursor. The precursor was activated in a tube furnace under a nitrogen atmosphere at a rate of 5℃ / min to a target temperature of 700℃ for 2 hours. After cooling to room temperature, the activated material was dispersed in 50mL of 1mol / L HCl solution and placed at 80℃ for 1 hour, followed by rinsing with deionized water until the pH reached neutral. After vacuum drying at 80℃ for 12 hours, the resulting coal-derived humic acid-based porous material was obtained and labeled HACs-5.

[0051] The structural characterization method for the HACs-5 porous material is described in Example 1. The specific surface area of ​​the HACs-5 porous material was measured to be 1115.16 m². 2 / g, with a microporous specific surface area of ​​738.50m². 2 / g, total pore volume is 0.377cm³3 / g of which has a micropore volume of 0.299cm³ 3 / g. The micropore size of HACs-5 was found to be concentrated in the ultramicropore range of 0.5-0.6 nm using the NLDFT model measured by the analysis software built into the testing software.

[0052] The product performance testing method for HACs-5 porous materials is described in Example 1. The static adsorption selectivity test results of this material for a mixture of CH4 and N2 at 25°C are shown in Table 1.

[0053]

Example 6

[0054] 4g of coal-derived humic acid and 2g of KOH solid were weighed and dispersed in 50mL of aqueous solution and stirred for 30 minutes. The mixture was then transferred to a 100mL hydrothermal reactor and hydrothermally reacted at 160℃ for 8 hours. The mixture after hydrothermal reaction was dried to obtain the HACs material precursor. The precursor was activated in a tube furnace under a nitrogen atmosphere at a rate of 5℃ / min to a target temperature of 800℃ for 2 hours. After cooling to room temperature, the activated material was dispersed in 50mL of 1mol / L HCl solution and placed at 80℃ for 1 hour, followed by rinsing with deionized water until the pH reached neutral. After vacuum drying at 80℃ for 12 hours, the resulting coal-derived humic acid-based porous material was obtained and labeled HACs-6.

[0055] The structural characterization method for the HACs-6 porous material is described in Example 1. The specific surface area of ​​the HACs-6 porous material was measured to be 1642.55 m². 2 / g, with a microporous specific surface area of ​​804.86m². 2 / g, total pore volume is 0.524cm³ 3 / g of which has a micropore volume of 0.345cm³ 3 / g. The micropore size of HACs-6 was found to be concentrated in the ultramicropore range of 0.5-0.6 nm using the NLDFT model measured by the built-in analysis software of the testing software.

[0056] The product performance testing method for HACs-6 porous materials is described in Example 1. The static adsorption selectivity test results of this material on a mixture of CH4 and N2 at 25°C are shown in Table 1.

[0057]

Example 7

[0058] 4g of coal-derived humic acid and 4g of KOH solid were weighed and dispersed in 50mL of aqueous solution and stirred for 30 minutes. The mixture was then transferred to a 100mL hydrothermal reactor and hydrothermally reacted at 160℃ for 8 hours. The mixture after hydrothermal reaction was dried to obtain the HACs material precursor. The precursor was activated in a tube furnace under a nitrogen atmosphere at a rate of 5℃ / min to a target temperature of 800℃ for 2 hours. After cooling to room temperature, the activated material was dispersed in 50mL of 1mol / L HCl solution and placed at 80℃ for 1 hour, followed by rinsing with deionized water until the pH reached neutral. After vacuum drying at 80℃ for 12 hours, the resulting coal-derived humic acid-based porous material was obtained and labeled HACs-7.

[0059] The structural characterization method for the HACs-7 porous material is described in Example 1. The specific surface area of ​​the HACs-7 porous material was measured to be 2065.90 m². 2 / g, with a microporous specific surface area of ​​608.91m². 2 / g, total pore volume is 0.631cm³ 3 / g of which the micropore volume is 0.302cm³ 3 / g. The micropore size of HACs-7 was found to be concentrated in the ultramicropore range of 0.5-0.6 nm using the NLDFT model measured by the analysis software built into the testing software.

[0060] The product performance testing method for HACs-7 porous materials is described in Example 1. The static adsorption selectivity test results of this material on a mixture of CH4 and N2 at 25°C are shown in Table 1.

[0061]

Example 8

[0062] 4g of coal-derived humic acid and 0.4g of NaOH solid were weighed and dispersed in 50mL of aqueous solution and stirred for 30 minutes. The mixture was then transferred to a 100mL hydrothermal reactor and hydrothermally reacted at 160℃ for 8 hours. The mixture after hydrothermal reaction was dried to obtain the HACs material precursor. The precursor was activated in a tube furnace under a nitrogen atmosphere at a rate of 5℃ / min to a target temperature of 700℃ for 2 hours. After cooling to room temperature, the activated material was dispersed in 50mL of 1mol / L HCl solution and placed at 80℃ for 1 hour, followed by rinsing with deionized water until the pH reached neutral. After vacuum drying at 80℃ for 12 hours, the resulting coal-derived humic acid-based porous material was obtained and labeled HACs-8.

[0063] The structural characterization method for the HACs-8 porous material is described in Example 1. The specific surface area of ​​the HACs-8 porous material was measured to be 621.88 m². 2 / g, with a microporous specific surface area of ​​552.24m². 2 / g, total pore volume is 0.388cm³3 / g of which has a micropore volume of 0.234cm³ 3 / g. The micropore size of HACs-8 was found to be concentrated in the ultramicropore range of 0.5-0.6 nm using the NLDFT model measured by the analysis software built into the testing software.

[0064] The product performance testing method for HACs-8 porous materials is described in Example 1. The static adsorption selectivity test results of this material on a mixture of CH4 and N2 at 25°C are shown in Table 1.

[0065] Table 1

[0066]

[0067] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A porous coal-derived humic acid material for separating CH4 / N2 in coalbed methane, characterized in that, The pore structure is mainly composed of micropores with a pore size concentrated in the range of 0.50-0.60 nm. The preparation method of the coal-derived humic acid porous material includes the following steps: 1) Mix alkaline activator and coal-derived humic acid at a mass ratio of 0.1:1-1:1, add deionized water, stir until uniform, transfer the mixture to a 100mL hydrothermal reactor, and then hydrothermally react at 160℃–180℃ for 8-10 hours. After the reaction is complete, let it stand, cool to room temperature, and dry the product to obtain the precursor of coal-derived humic acid porous material. 2) The precursor is transferred to a tube furnace and carbonized at a high temperature of 600℃-800℃ under an inert atmosphere. After carbonization, the temperature is lowered to room temperature, the solid material is taken out, and after acid washing, filtration and drying, the coal-derived humic acid porous material is obtained.

2. The porous coal-derived humic acid material for separating CH4 / N2 in coalbed methane as described in claim 1, characterized in that, The alkaline activator is potassium hydroxide or sodium hydroxide.

3. The porous coal-derived humic acid material for separating CH4 / N2 in coalbed methane as described in claim 1, characterized in that, The mixture undergoes a hydrothermal reaction at a temperature of 160°C for 8 hours.

4. The application of the porous coal-derived humic acid material according to claim 1 in the separation and enrichment of coalbed methane, characterized in that, The adsorption method was used to separate CH4 / N2 in coalbed methane using the aforementioned coal-derived humic acid porous material; the operating conditions for the adsorption process were a temperature of 0℃-30℃ and a pressure of 0.1MPa-1MPa.

Images