Preparation method and application of carbon capture material suitable for small biogas power generation

Abstract

The invention provides a preparation method and application of a carbon capture material suitable for small biogas power generation. The method comprises the following steps: S1, preparing a preparation solvent A of a KAUST-7 organic metal framework by using absolute ethyl alcohol and high-purity water; s2, mixing N NbOF5 with the solvent A in the step S1 to prepare an N NbOF5 solution; s3, mixing pyrazine, MEA and the solvent A in the step S1 to prepare a pyrazine-MEA solution; and S4, putting a proper amount of large-aperture molecular sieves into a reaction kettle according to the proportion that 1g of the Ni NbOF5 solution is matched with 150g of molecular sieves, adding the Ni NbOF5 solution and the pyrazine-MEA solution, quickly stirring uniformly, reacting, naturally cooling, washing with high-purity water and absolute ethyl alcohol in sequence, and drying to obtain the carbon capture material. The carbon capture material prepared by the preparation method of the carbon capture material suitable for small biogas power generation is mounted in adsorption equipment to be used for separating and capturing CO2 in flue gas without external power, the desorption process can be carried out in a low-temperature state, and the carbon capture material can be repeatedly used for multiple times.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon capture, and in particular, relates to a method for preparing a CO2 capture material suitable for low-flow, intermittent, heat-source-free small-scale biogas power generation and a non-powered device for carbon capture using the material. Background Art

[0002] Under the same calorific value conditions, the carbon emissions of natural gas are about 55% of those of coal. In the strategic context of achieving the "dual carbon" goal, the proportion of natural gas in the energy structure will gradually increase in the future. Rural areas have natural biomass renewable energy. Using biomass energy to produce natural gas and realizing the integration and linkage of natural gas and renewable energy is not only conducive to ensuring energy security, but also to promoting the good development of the ecological environment. On this basis, the carbon capture technology coupled with rural small-scale biogas power generation projects can further reduce carbon emissions in all links, and the carbon-rich gas produced by desorption can also be used for agricultural production, so that the whole system can achieve the beneficial effect of zero carbon or even negative carbon.

[0003] However, the capture material used in traditional carbon capture technology is an amine-functionalized adsorbent, which has high selectivity and strong stability for CO2, and the temperature needs to be continuously increased during the desorption process, and the desorption concentration is only available in the highest concentration. Small-scale biogas power generation projects have the characteristics of low exhaust flow, intermittent operation, and no additional heat source during operation, and the carbon-rich gas used for agricultural production does not require high-concentration CO2. Obviously, traditional carbon capture materials and devices cannot adapt to the resource utilization of CO2 in the current agricultural scenario, so further improvement is urgently needed. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation method and application of a carbon capture material suitable for small-scale biogas power generation in agricultural production scenarios. The carbon capture material prepared by the present invention can selectively adsorb CO2 under low flow and no power, the desorption process can be carried out under low temperature conditions, and can be reused many times.

[0005] In order to achieve the above technical objectives, the present invention provides a method for preparing a carbon capture material suitable for small-scale biogas power generation, which specifically comprises the following steps:

[0006] S1. Prepare solvent A for preparing KAUST-7 organic metal framework using anhydrous ethanol and high-purity water, wherein the mass ratio of anhydrous ethanol to high-purity water in solvent A is 3.5-4.0:1-1.2;

[0007] S2, preparing a NiNbOF5 solution by mixing NiNbOF5 with the solvent A in step S1, and subjecting the solution to ultrasonic dispersion treatment at room temperature until the solution becomes clear and transparent; in the NiNbOF5 solution, the mass ratio of NiNbOF5 to solvent A is 7-7.5:10-11.5;

[0008] S3, preparing a pyrazine-MEA solution by mixing pyrazine, MEA (ethanolamine) and the solvent A in step S1, and performing ultrasonic dispersion treatment at room temperature until the solution becomes clear and transparent; in the pyrazine-MEA solution, the mass ratio of pyrazine, MEA and solvent A is 1.5-2.0:1.8-2.5:10-15;

[0009] S4. According to the ratio of 1g NiNbOF5 solution to 150g molecular sieve, a proper amount of large-pore molecular sieve is placed in a reactor, and NiNbOF5 solution and pyrazine-MEA solution are added and quickly stirred evenly, and the mixture is reacted at 110-125° C. for 24 hours, and naturally cooled to room temperature to prepare a molecular sieve attached with a KAUST-7 organic metal framework; wherein the pore size range of the large-pore molecular sieve is 100-150nm, and the mass ratio of the NiNbOF5 solution to the pyrazine-MEA solution is 1-1.2:40-65;

[0010] S5. The molecular sieve attached with the KAUST-7 organic metal framework prepared in step S4 is washed with high-purity water and anhydrous ethanol successively, and then placed in an oven at 80-90° C. to dry to obtain the carbon capture material.

[0011] A further technical solution of the present invention: The NiNbOF5 in step S2 is prepared by the following method: reactants are added and mixed in sequence according to a molar ratio of 1Nb2O5:2NiO:10HF, and stirred continuously for 2 to 4 hours at room temperature, and then transferred to a reactor, kept at 100 to 120°C for reaction for 24 hours, cooled to 25 to 28°C with cold water, opened the reactor and poured into an evaporating dish, and evaporated at 60 to 70°C to obtain green NiNbOF5 crystals; the green NiNbOF5 crystals and the solvent A in step S1 are prepared into a NiNbOF5 solution.

[0012] A preferred technical solution of the present invention: the mass ratio of anhydrous ethanol to high-purity water in the solvent A of step S1 is 3.8-4.0:1.

[0013] A preferred technical solution of the present invention: in step S3, in the pyrazine-MEA solution, the mass of MEA is the same as the mass of pyrazine.

[0014] A preferred technical solution of the present invention: In step S4, the NiNbOF5 solution and the pyrazine-MEA solution are mixed at 5 to 10° C. and then placed in a reaction kettle containing an appropriate amount of large-pore molecular sieve; the large-pore molecular sieve is a phosphate aluminate molecular sieve.

[0015] The present invention also provides an application of the carbon capture material prepared by the above method suitable for small-scale biogas power generation, specifically, the carbon capture material prepared by the above method for preparing the carbon capture material suitable for small-scale biogas power generation is installed in an adsorption device for separating and capturing CO2 in flue gas without external power.

[0016] A further technical solution of the present invention is as follows: the adsorption device comprises a box body with a photovoltaic cell and a carbon capture material module installed in the box body, the lower part of the box body is provided with an air inlet channel, the top part of the box body is provided with an air outlet channel, and the box body is provided with multiple layers of carbon capture material modules from bottom to top; the carbon capture material module comprises an outer shell body with upper and lower openings and a metal mesh partition placed in the middle of the outer shell body, the upper and lower open surfaces of the outer shell body are respectively covered with PTFE filter membranes, and the metal mesh partition inside the outer shell body is filled with carbon capture materials suitable for small-scale biogas power generation above and below.

[0017] A further technical solution of the present invention is as follows: CO2 monitoring instruments are respectively installed on the air inlet channel and the air outlet channel of the box body, and the CO2 monitoring instruments are connected to the external control device signal through a signal line; the air inlet channel of the box body is connected to the biogas tail flue gas exhaust pipe of the small biogas power generation device, and during the operation of the adsorption equipment, the carbon capture material module is heated to 60-85°C.

[0018] The preferred technical solution of the present invention is as follows: the box body is a hollow shell structure closed on four sides, and multiple layers of supporting slide rails are correspondingly provided on the two side walls inside the box body, and the box body is divided into a plurality of hollow compartments for pulling out and inserting carbon capture material modules through the supporting slide rails, and a cavity opening is correspondingly opened on the front side of the box body; the carbon capture material module is arranged in a drawer shape, and slide rails matching the supporting slide rails are provided on both sides of the bottom thereof, and the module is inserted into the corresponding hollow compartment through the cavity opening on the front side of the box body; an air inlet cavity connected to the compartment of the box body is provided at the bottom of the box body, and the air inlet channel is connected to the air inlet cavity, and a desiccant is filled in the air inlet cavity; an air outlet cavity connected to the compartment of the box body is provided at the top of the box body, and the air outlet channel is connected to the air outlet cavity.

[0019] A preferred technical solution of the present invention is as follows: the pore diameter of the PTFE filter membrane is 12-15 μm, a heating wire is provided on the metal mesh, and when the carbon capture material module is desorbed, the heating wire heats the carbon capture material module to 60-85° C.

[0020] In the present invention, the tail flue gas of biogas enters from the air inlet of the box, passes through the carbon capture module stored in the box, and is discharged from the top channel. The CO2 monitoring instrument installed on the inlet and outlet monitors the current CO2 concentration, temperature and other data in real time; the carbon capture module is a drawer type. When the box with multiple layers of the carbon capture module is installed is in operation, the tail flue gas of biogas enters from the bottom of the module through the PTFE filter membrane and is discharged from the top to complete the capture of CO2.

[0021] Beneficial effects of the present invention:

[0022] (1) After a certain amount of ethanol is added to the solvent for preparing the KAUST-7 organic metal framework in the present invention, the ethanol will be adsorbed on the surface of the KAUST-7 crystal and act as a capping agent, forcing the crystallinity and size to decrease from the traditional 500 nm to less than 200 nm;

[0023] (2) Adding MEA organic base to the pyrazine solution can increase the supersaturation of the synthetic solution. The organic ligand pyrazine is more likely to react with the metal ion Ni. 2+ Coordination improves the growth rate of KAUST-7 crystals and makes it easy to obtain ultrafine crystals below 100nm;

[0024] (3) Molecular sieves with pore sizes exceeding 100 nm have a large number of cavities inside. During the synthesis of KAUST-7, they can serve as nucleation sites to promote the formation of KAUST-7 crystals. On the other hand, they can weaken the crystal agglomeration phenomenon caused by small grains. Ultimately, KAUST-7 crystals with a size below 100 nm can be stably present in the pores of the molecular sieve. As a carbon capture material, they can selectively adsorb CO2 under low flow and no power.

[0025] (4) Washing the carbon capture material with anhydrous ethanol can clean the MEA on it, avoid chemical absorption that is difficult to desorb during the carbon capture process, improve the physical absorption efficiency, and reduce the difficulty of release;

[0026] (5) The present invention uses only KAUST-7 organic metal framework for carbon capture, which has a high cost (the market price of 1 kg is 50,000 yuan), while the use of molecular sieve as a matrix can significantly reduce the cost of material use (the cost of large-pore molecular sieve is only 200 yuan / kg). Since rural carbon capture application scenarios do not require high-concentration CO2 release, the molecular sieve attached with KAUST-7 is sufficient to meet the demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the adsorption device in the present invention;

[0028] Figure 2 It is a structural schematic diagram of the adsorption box in the present invention;

[0029] Figure 3 It is a structural schematic diagram of the carbon capture module in the present invention.

[0030] In the figure: 1—box body, 100—support slide rail, 101—hollow compartment, 102—air inlet chamber, 103—air outlet chamber, 2—air inlet passage, 3—air outlet passage, 4—carbon capture material module, 400—outer shell, 401—metal mesh partition, 402—PTFE filter membrane, 403—carbon capture material, 404—slideway, 5—CO2 monitoring instrument, 6—control device. DETAILED DESCRIPTION

[0031] The following will be combined with the accompanying drawings in the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The NiNbOF5 in the following examples is prepared by the following method: the reactants are added and mixed in sequence according to a molar ratio of 1Nb2O5:2NiO:10HF, and stirred continuously for 2 to 4 hours at room temperature. Then, the reactants are transferred to a reactor and reacted at 100 to 120°C for 24 hours. The reactants are cooled to 25 to 28°C with cold water, and the reactor is opened and poured into an evaporating dish. The reactants are evaporated at 60 to 70°C to obtain green NiNbOF5 crystals.

[0033] A carbon capture material for small-scale biogas power generation in agricultural production scenarios provided in Example 1 is prepared by:

[0034] S1. Prepare solvent A for preparing KAUST-7 organic metal framework using anhydrous ethanol and high-purity water, wherein the mass ratio of anhydrous ethanol to high-purity water in solvent A is 4:1;

[0035] S2, preparing a NiNbOF5 solution by mixing NiNbOF5 with the solvent A in step S1, and subjecting the mixture to ultrasonic dispersion treatment at room temperature until the mixture is clear and transparent; in the NiNbOF5 solution, the mass ratio of NiNbOF5 to solvent A is 7.5:11;

[0036] S3, using the solvent A in step S1 to prepare a 1:1 pyrazine-MEA solution, and subjecting the solution to ultrasonic dispersion treatment at room temperature until the solution is clear and transparent; in the pyrazine-MEA solution, the mass ratio of pyrazine, MEA (ethanolamine) and S1 solvent is 1:1:5;

[0037] S4, firstly mixing 1 part of NiNbOF5 solution and 50 parts of pyrazine-MEA solution at 5°C, then putting an appropriate amount of aluminophosphate large-pore molecular sieve into a reactor, reacting at 120°C for 24 hours, and naturally cooling to room temperature to prepare a molecular sieve attached with a KAUST-7 organic metal framework; wherein the pore size range of the large-pore molecular sieve is 100-150nm;

[0038] S5. The molecular sieve attached to the KAUST-7 organic metal framework is washed with high-purity water and anhydrous ethanol successively, and then placed in an oven at 80-90° C. to dry to obtain the molecular sieve attached to KAUST-7, i.e., the carbon capture material A.

[0039] Example 2 provides a new type of carbon capture material suitable for agricultural production scenarios, and its preparation includes the following steps:

[0040] S1. Prepare solvent A for preparing KAUST-7 organic metal framework using anhydrous ethanol and high-purity water, wherein the mass ratio of anhydrous ethanol to high-purity water in solvent A is 3.8:1;

[0041] S2, preparing a NiNbOF5 solution by mixing NiNbOF5 with the solvent A in step S1, and subjecting the solution to ultrasonic dispersion treatment at room temperature until the solution is clear and transparent; in the NiNbOF5 solution, the mass ratio of NiNbOF5 to the solvent S1 is 7:11;

[0042] S3, using the solvent in step S1 to prepare a 1:1 pyrazine-MEA solution, and subjecting it to ultrasonic dispersion treatment at room temperature until it is clear and transparent; in the pyrazine-MEA solution, the mass ratio of pyrazine, MEA and S1 solvent is 1.8:1.8:15;

[0043] S4, firstly mixing 1 part of NiNbOF5 solution and 40 parts of pyrazine-MEA solution at 5°C, then putting an appropriate amount of large-pore molecular sieve into a reactor, reacting at 120°C for 24 hours, and naturally cooling to room temperature to prepare a molecular sieve attached with KAUST-7 organic metal framework; wherein the pore size range of the large-pore molecular sieve is 100-150nm;

[0044] S5. The molecular sieve attached to the KAUST-7 organic metal framework is washed with high-purity water and anhydrous ethanol successively, and then placed in an oven at 80-90° C. to dry to obtain the molecular sieve attached to KAUST-7, i.e., the carbon capture material B.

[0045] Example 3 provides a new type of carbon capture material suitable for agricultural production scenarios, and its preparation includes the following steps:

[0046] S1. Prepare solvent A for preparing KAUST-7 organic metal framework using anhydrous ethanol and high-purity water, wherein the mass ratio of anhydrous ethanol to high-purity water in solvent A is 3.8:1.2;

[0047] S2, preparing a NiNbOF5 solution by mixing NiNbOF5 with the solvent A in step S1, and subjecting the mixture to ultrasonic dispersion treatment at room temperature until the mixture is clear and transparent; in the NiNbOF5 solution, the mass ratio of NiNbOF5 to the solvent S1 is 7:10;

[0048] S3, using the solvent in step S1 to prepare a 1:1 pyrazine-MEA solution, and subjecting it to ultrasonic dispersion treatment at room temperature until it is clear and transparent. In the pyrazine-MEA solution, the mass ratio of pyrazine, MEA and S1 solvent is 2:2:12;

[0049] S4, firstly mixing 1 part of NiNbOF5 solution and 60 parts of pyrazine-MEA solution at 10°C, then putting an appropriate amount of large-pore molecular sieve into a reactor, reacting at 120°C for 24 hours, and naturally cooling to room temperature to prepare a molecular sieve attached with a KAUST-7 organic metal framework; wherein the pore size range of the large-pore molecular sieve is 100-150nm;

[0050] S5. The molecular sieve attached to the KAUST-7 organic metal framework is washed with high-purity water and anhydrous ethanol successively, and then placed in an oven at 80-90° C. to dry to obtain the molecular sieve attached to KAUST-7, i.e., the carbon capture material C.

[0051] In Example 4, the carbon capture materials A, B, C prepared in Examples 1, 2, and 3, the traditional molecular sieve carbon capture material D, and the calcium lime carbon capture material E are respectively loaded into a carbon capture module, and installed in an adsorption device, connected to a fixed emission source for separating and capturing CO2 in the flue gas without external power, and the adsorbed solid carbon capture material is desorbed and released for cyclic capture.

[0052] The adsorption device in Example 4, such as Figures 1 to 3As shown, it includes a box 1 with a photovoltaic cell and a carbon capture material module installed in the box 1. The lower part of the box 1 is provided with an air inlet channel 2, and the top is provided with an air outlet channel 3. The air inlet channel 2 and the air outlet channel 3 of the box 1 are respectively installed with a CO2 monitoring instrument 5, and the CO2 monitoring instrument 5 is connected to the external control device 6, i.e., the upper computer signal through a signal line; the box 1 is provided with multiple layers of carbon capture material modules from bottom to top. The carbon capture material module 4 includes an outer shell 400 with upper and lower openings and a metal mesh partition 401 placed in the middle of the outer shell, and the upper and lower open surfaces of the outer shell are respectively covered with a PTFE filter membrane 402, and the metal mesh partition 401 in the outer shell 400 is filled with carbon capture materials 403 suitable for small-scale biogas power generation. The filter pore diameter of the PTFE filter membrane is 12 to 15 μm, and the metal mesh 401 is provided with a heating wire.

[0053] The box body 1 in the embodiment is a hollow shell structure closed on four sides. Figure 2 As shown, multi-layer support rails 100 are provided on both side walls of the box body 1, and the box body 1 is divided into a plurality of hollow compartments 101 for inserting and withdrawing the carbon capture material module 4 by the support rails 100, and a cavity opening is provided on the front side of the box body 1; Figure 3 As shown, the carbon capture material module 4 is arranged in a drawer shape, and slideways 404 matching the support slide rails 100 are arranged on both sides of the bottom, and are inserted into the corresponding hollow compartment 101 through the cavity opening on the front of the box body 1; the end of the carbon capture material module 4 is provided with a baffle that can seal and block the hollow compartment 101. After the carbon capture material module 4 is inserted into the hollow compartment 101, the entire front of the box body is blocked and closed by the baffle to prevent smoke from escaping. An air inlet cavity 102 connected to the compartment of the box body is arranged at the bottom of the box body 1, and the air inlet channel 2 is connected to the air inlet cavity 102, and the air inlet cavity 102 is filled with a desiccant, which can adsorb moisture in the smoke; an air outlet cavity 103 connected to the compartment of the box body is arranged at the top of the box body 1, and the air outlet channel 3 is connected to the air outlet cavity 103. The air inlet channel 2 of the box 1 is connected to the flue gas exhaust pipe of the small biogas power generation device, and the carbon capture material module is heated to 60-85° C. during the operation of the adsorption device. When the carbon capture material module is desorbed, the carbon capture material module is heated to 60-85° C. by the heating wire.

[0054] Example 5: The adsorption device in Example 4 is applied to the back end of a biogas power generation device of a rural energy revolution technology demonstration project in Hubei Province, and the CO2 capture process data is recorded using an existing monitoring system. The steps are as follows:

[0055] S1. The flue gas velocity at the tail of the biogas power generation is 10 m / s. The carbon capture materials A, B, C prepared in Examples 1, 2, and 3, the traditional molecular sieve carbon capture material D, and the calcium lime carbon capture material E are respectively loaded into the carbon capture module and installed in the adsorption equipment for testing.

[0056] S2. Control the operation time of the biogas generator from 8:00 to 20:00 every day. After 1.2L of each material is put into the box, it will run for 3 days and then the whole box will be taken out. During this period, the CO2 content in the inlet and outlet flue gas will be monitored.

[0057] S3. Power on and heat the module partitions in the box to 60°C, and examine the CO2 content at the outlet of the module device.

[0058] S4. Repeat the test twice on the same batch of materials to confirm that the new adsorbent material still has strong adsorption capacity after multiple uses.

[0059] The test results of the adsorption performance of materials and devices are shown in Table 1 below:

[0060] Table 1 CO2 adsorption capacity of different carbon capture materials

[0061]

[0062] It can be seen from Table 1 above that the carbon capture material prepared in the embodiment of the present invention has a better carbon capture effect than the traditional molecular sieve, is substantially the same as the carbon capture effect of lime, and also has cycle stability.

[0063] The test results of the release process after capture are shown in Table 2 below:

[0064] Table 2 Desorption and release capacity of different carbon capture materials

[0065]

[0066] It can be seen from Table 2 above that the carbon capture material prepared in the embodiment of the present invention has a faster desorption and release effect than the traditional molecular sieve. At the same time, due to the strong stability of calcium lime, desorption and release cannot be completed at 60°C, indicating that the carbon capture material prepared in the embodiment of the present invention has better low-temperature release ability than calcium lime.

[0067] Example 6: The carbon capture materials A, B, C prepared in Examples 1, 2, and 3, the traditional molecular sieve carbon capture material D, and the calcium lime carbon capture material E are respectively loaded into the carbon capture module, and installed in the adsorption device in Example 4, and applied to the rear end of a rural 10L heating stove. The CO2 concentration in and out of the device is recorded by a portable computer, and the steps are as follows:

[0068] S1. The flue gas velocity at the tail end of the stove is 1 m / s. The five carbon capture materials mentioned above are placed in a box for testing.

[0069] S2. Control the heating stove to run continuously for 24 hours in winter. Take 1.5L of each carbon capture material and put it into the box. Run it for 7 days and then take out the whole box. During this period, monitor the CO2 content in the inlet and outlet flue gas.

[0070] S3. Heat the module partitions in the box to 70°C and check the CO2 content at the outlet of the module device.

[0071] S4. Repeat the test twice on the same batch of materials to confirm that the new adsorbent material still has strong adsorption capacity after multiple uses.

[0072] The test results of the adsorption performance of materials and devices are shown in Table 1 below:

[0073] Table 1 CO2 adsorption capacity of different carbon capture materials

[0074]

[0075]

[0076] It can be seen from Table 1 above that under long-term adsorption at low flow rates, the five materials are basically saturated after running for 7 days. The carbon capture material prepared in the embodiment of the present invention still has a better carbon capture effect, which is the same as the carbon capture effect of calcium lime, and also has a certain cycle stability.

[0077] The test results of the release process after capture are shown in Table 2 below:

[0078] Table 2 Desorption and release capacity of different carbon capture materials

[0079]

[0080] It can be seen from Table 2 above that the carbon capture material prepared in the embodiment of the present invention still has a faster desorption and release effect than the traditional molecular sieve under the adsorption saturation state. Similarly, due to the strong stability of calcium lime, desorption and release cannot be completed at 60°C, indicating that the carbon capture material prepared in the embodiment of the present invention has better low-temperature release ability than calcium lime.

[0081] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0082] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a carbon capture material suitable for small-scale biogas power generation, characterized in that: The specific steps include: S1. Prepare solvent A for preparing KAUST-7 organic metal framework using anhydrous ethanol and high-purity water, wherein the mass ratio of anhydrous ethanol to high-purity water in solvent A is 3.5-4.0:1-1.2; S2, preparing a NiNbOF5 solution by mixing NiNbOF5 with the solvent A in step S1, and subjecting the solution to ultrasonic dispersion treatment at room temperature until the solution becomes clear and transparent; in the NiNbOF5 solution, the mass ratio of NiNbOF5 to solvent A is 7-7.5:10-11.5; S3, preparing a pyrazine-MEA solution by mixing pyrazine, MEA and the solvent A in step S1, and performing ultrasonic dispersion treatment at room temperature until the solution becomes clear and transparent; in the pyrazine-MEA solution, the mass ratio of pyrazine, MEA and solvent A is 1.5-2.0:1.8-2.5:10-15; S4. According to the ratio of 1g NiNbOF5 solution to 150g molecular sieve, a proper amount of large-pore molecular sieve is placed in a reactor, and NiNbOF5 solution and pyrazine-MEA solution are added and quickly stirred evenly, and the mixture is reacted at 110-125° C. for 24 hours, and naturally cooled to room temperature to prepare a molecular sieve attached with a KAUST-7 organic metal framework; wherein the pore size range of the large-pore molecular sieve is 100-150nm, and the mass ratio of the NiNbOF5 solution to the pyrazine-MEA solution is 1-1.2:40-65; S5. The molecular sieve attached with the KAUST-7 organic metal framework prepared in step S4 is washed with high-purity water and anhydrous ethanol successively, and then placed in an oven at 80-90° C. to dry to obtain the carbon capture material.

2. The method for preparing a carbon capture material suitable for small-scale biogas power generation according to claim 1, characterized in that: The NiNbOF5 in step S2 is prepared by the following method: the reactants are added and mixed in sequence according to a molar ratio of 1Nb2O5:2NiO:10HF, and stirred continuously for 2 to 4 hours at room temperature, and then transferred to a reactor, kept at 100 to 120°C for reaction for 24 hours, cooled to 25 to 28°C with cold water, the reactor is opened and poured into an evaporating dish, and evaporated at 60 to 70°C to obtain green NiNbOF5 crystals; the above green NiNbOF5 crystals are prepared into a NiNbOF5 solution with the solvent A in step S1.

3. A method for preparing a carbon capture material suitable for small-scale biogas power generation according to claim 1 or 2, characterized in that: The mass ratio of anhydrous ethanol to high-purity water in the solvent A of step S1 is 3.8-4.0:

1.

4. A method for preparing a carbon capture material suitable for small-scale biogas power generation according to claim 1 or 2, characterized in that: In step S3, in the pyrazine-MEA solution, the mass of MEA is the same as the mass of pyrazine.

5. A method for preparing a carbon capture material suitable for small-scale biogas power generation according to claim 1 or 2, characterized in that: In step S4, the NiNbOF5 solution and the pyrazine-MEA solution are mixed at 5-10° C. and then placed in a reaction kettle containing an appropriate amount of large-pore molecular sieve; the large-pore molecular sieve is a phosphate aluminate molecular sieve.

6. An application of a carbon capture material prepared by the method of any one of claims 1 to 5 suitable for small-scale biogas power generation, characterized in that: The carbon capture material prepared by the method for preparing the carbon capture material suitable for small-scale biogas power generation is installed in an adsorption device for separating and capturing CO2 in flue gas without external power.

7. The use of a carbon capture material suitable for small-scale biogas power generation according to claim 6, characterized in that: The adsorption device comprises a box (1) with a photovoltaic cell and a carbon capture material module installed in the box (1); the lower part of the box (1) is provided with an air inlet channel (2), and the top part is provided with an air outlet channel (3); the box (1) is provided with multiple layers of carbon capture material modules from bottom to top; the carbon capture material module (4) comprises an outer shell (400) with upper and lower openings and a metal mesh partition (401) arranged in the middle of the outer shell, the upper and lower open surfaces of the outer shell are respectively covered with PTFE filter membranes (402), and the upper and lower metal mesh partitions (401) in the outer shell (400) are filled with carbon capture materials (403) suitable for small-scale biogas power generation.

8. The use of a carbon capture material suitable for small-scale biogas power generation according to claim 7, characterized in that: A CO2 monitoring instrument (5) is installed on the air inlet channel (2) and the air outlet channel (3) of the housing (1), respectively. The CO2 monitoring instrument (5) is connected to an external control device (6) via a signal line; the air inlet channel (2) of the housing (1) is connected to a biogas tail flue gas exhaust pipe of a small biogas power generation device, and during the operation of the adsorption device, the carbon capture material module is heated to 60 to 85°C.

9. The use of a carbon capture material suitable for small-scale biogas power generation according to claim 7, characterized in that: The box (1) is a hollow shell structure closed on four sides, and multiple layers of supporting slide rails (100) are provided on the two side walls of the box (1) respectively. The supporting slide rails (100) divide the box (1) into multiple hollow compartments (101) for inserting and removing the carbon capture material module (4), and a cavity opening is provided on the front side of the box (1); the carbon capture material module (4) is arranged in a drawer shape, and two sides of the bottom thereof are provided with corresponding supporting slide rails (100). The air inlet (102) is connected to the compartment of the box body (1) and is provided with a slideway (404) and inserted into the corresponding hollow compartment (101) through the cavity on the front side of the box body (1); an air inlet cavity (102) communicating with the compartment of the box body is provided at the bottom of the box body (1); the air inlet channel (2) is connected to the air inlet cavity (102), and the air inlet cavity (102) is filled with a desiccant; an air outlet cavity (103) communicating with the compartment of the box body is provided at the top of the box body (1); the air outlet channel (3) is connected to the air outlet cavity (103).

10. The use of a carbon capture material suitable for small-scale biogas power generation according to claim 7 or 8, characterized in that: The pore diameter of the PTFE filter membrane is 12-15 μm. The metal mesh (401) is provided with a heating wire, and when the carbon capture material module is desorbed, the heating wire heats the carbon capture material module to 60-85° C.

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