System and method for preparing green fuel by coupling direct air trapping with in-situ catalytic conversion

Abstract

The invention belongs to the field of CO2 capture, utilization and storage, and relates to a system and a method for preparing a green fuel by coupling direct air capture with in-situ catalytic conversion. The system comprises an electric energy supply and storage unit, a gas generation and control unit, an adsorption and conversion unit and a product collection and detection unit, and the electric energy supply and storage unit is electrically connected with the gas generation and control unit, the adsorption and conversion unit and the product collection and detection unit. The gas generation and control unit, the adsorption and conversion unit and the product collection and detection unit are connected in sequence. The electric energy supply and storage unit can utilize renewable energy sources to generate electricity and provide electric power for the whole system; the gas generation and control unit can form corresponding gas for adsorption, conversion and purging; the adsorption and conversion unit can realize capture and direct catalytic conversion of CO2 in air to form green fuel; the product collection and detection unit can be used for separating and collecting the generated green fuel and detecting the green fuel.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of CO2 capture, utilization and storage, and particularly relates to a system and method for directly air capturing coupled with in-situ catalytic conversion to prepare green fuel. BACKGROUND

[0002] Global warming has become a global focus, and the large-scale emission of carbon dioxide is the main cause. Carbon dioxide capture, utilization and storage technology is becoming a new way to alleviate carbon dioxide emissions. However, carbon dioxide capture, utilization and storage technology currently faces a series of challenges, including high energy consumption, immature technology, low conversion rate in carbon utilization process, and high cost of carbon dioxide compression, liquefaction and transportation process connecting carbon capture and utilization, which seriously restricts the development and application of the technology. SUMMARY

[0003] The present application is based on the discovery and understanding of the inventors of the following facts and problems: Carbon capture coupled with in-situ conversion technology can realize carbon dioxide capture and conversion in the same reactor, saving the intermediate steps of carbon dioxide compression, liquefaction and transportation, and directly converting the captured carbon dioxide into high-value chemicals.

[0004] Direct air capture technology can directly enrich CO2 in air, and is a very potential carbon negative technology. However, the cost of direct air capture technology is high, and the desorption energy consumption is large, which has become the main factor restricting the development of direct air capture technology. Further, using green renewable energy as energy input and using electrolysis of water to produce green hydrogen as hydrogen input can prepare low-carbon green fuel, which has very high economic value. However, the current use of direct air capture is still in its infancy, and the combination of direct air capture and in-situ conversion to prepare green fuel requires matching the conditions of capture and catalytic process, which is difficult. Therefore, it is of great significance to combine direct air capture technology with carbon capture coupled with in-situ conversion technology, and to develop a system and method for directly air capturing coupled with in-situ catalytic conversion to prepare green fuel.

[0005] The present application aims to at least partially alleviate or solve at least one of the above-mentioned problems.

[0006] In one aspect of the present application, the present application provides a system for directly air capturing and in-situ catalytic conversion to prepare green fuel. In some embodiments of the present application, the system for directly air capturing and in-situ catalytic conversion to prepare green fuel comprises an electric energy supply and storage unit, a gas generation and control unit, an adsorption and conversion unit, and a product collection and detection unit, wherein the electric energy supply and storage unit comprises a renewable energy power generation device and an electric energy storage device, the electric energy supply and storage unit is electrically connected with the gas generation and control unit, the adsorption and conversion unit, and the product collection and detection unit respectively, and the gas generation and control unit, the adsorption and conversion unit, and the product collection and detection unit are connected in sequence. Thus, the electric energy supply and storage unit can generate electricity by using renewable energy and store the generated electric energy to provide electric power for the whole system, which can reduce the cost of system operation; the gas generation and control unit can form corresponding gases for adsorption, conversion and purging to provide the required gases for the adsorption and conversion unit; the adsorption and conversion unit can realize the capture and direct catalytic conversion of CO2 in air to form green fuel; and the product collection and detection unit can be used for separating and collecting the generated green fuel and detecting the same.

[0007] In some embodiments of the present application, the renewable energy power generation device comprises at least one of a solar photovoltaic, a wind turbine, and a tidal energy conversion device.

[0008] In some embodiments of the present application, the electric energy storage device comprises a battery.

[0009] In some embodiments of the present application, the gas generation and control unit comprises an air compressor, a hydrogen generator, and a nitrogen generator, and the air compressor, the hydrogen generator, and the nitrogen generator are connected with the adsorption and conversion unit.

[0010] In some embodiments of the present application, the gas generation and control unit comprises an air controller, a hydrogen controller, and a nitrogen controller, the air controller is connected with the air compressor and the adsorption and conversion unit respectively, the hydrogen controller is connected with the hydrogen generator and the adsorption and conversion unit respectively, and the nitrogen controller is connected with the nitrogen generator and the adsorption and conversion unit respectively.

[0011] In some embodiments of the present application, the adsorption and conversion unit comprises a fixed bed and / or a fluidized bed, the bed layer of the fixed bed and / or the bed layer of the fluidized bed is packed with a bifunctional material having the functions of directly air capturing and catalysis, for realizing the capture and direct in-situ catalytic conversion of CO2 in air, wherein the bifunctional material comprises an adsorption component and a catalysis component.

[0012] In some embodiments of the present application, the product collection and detection unit is used for detecting the product and separating and collecting the product.

[0013] In some embodiments of the present application, the green fuel comprises one or more of carbon monoxide, methane, methanol, and olefins.

[0014] In some embodiments of the present application, the product collection and detection unit comprises a condenser, a gas-liquid separator, and an online analysis device, the condenser is located at the feed inlet of the gas-liquid separator, and the online analysis device comprises at least one of a gas chromatograph, a liquid chromatograph, a mass spectrometer, and a flue gas analyzer.

[0015] In another aspect of the present application, a method for directly air capturing coupled with in-situ catalytic conversion to prepare green fuel is provided, which utilizes the system described above for air capturing and in-situ catalytic conversion, comprising the following steps: S1: The power supply and storage unit provides power for the system by converting renewable energy into electrical energy and storing it; S2: A dual-functional material with adsorption and catalytic functions is placed in the adsorption and conversion unit; S3: Air is introduced into the adsorption and conversion unit by the gas generation and control unit, the dual-functional material adsorbs CO2 in the air, and the CO2-removed air is discharged from the system; S4: Nitrogen gas is introduced into the adsorption and conversion unit by the gas generation and control unit to purge the air in the adsorption and conversion unit; S5: Hydrogen gas is introduced into the adsorption and conversion unit by the gas generation and control unit and the dual-functional material is heated, the dual-functional material releases the adsorbed CO2 and converts it into green fuel in-situ; S6: The generated green fuel is introduced into the product collection and detection unit, and the obtained product is detected, separated, and collected; S7: Repeat S3-S6.

[0016] Direct air capturing coupled with in-situ conversion can combine the direct air capturing process with the carbon conversion process, significantly reduce the desorption temperature of the direct air capturing process, and be beneficial to reduce the energy consumption of air capturing and in-situ catalytic conversion and improve the energy utilization efficiency; using green electricity generated by renewable energy as energy input can significantly reduce the energy consumption required for system operation.

[0017] In some embodiments of the present application, during system operation, the real-time power P gen of the renewable energy power generation device is combined with the existing storage power Q of the power supply and storage unit, and the power consumption P cap of the system for direct air capturing and the power consumption P conThe breakthrough time t of direct air capture of the bifunctional material cap The conversion time t of the bifunctional material under adsorption breakthrough condition con The subsequent process is dynamically adjusted based on the length of air capture t1 that has been performed by the bifunctional material.

[0018] In some embodiments of the present application, the optimal capture end time and conversion time are determined and dynamically adjusted according to the following constraint conditions: Conversion time constraint: t3= (t1+t2) / t cap ×t con Equation (1); Capture time constraint: t1+t2≤ t cap Equation (2); Energy constraint: P cap ×t2+P con ×t3≤ P gen ×(t2+t3)+η×Q Equation (3); Wherein, η is the energy surplus coefficient of the system, taking 0.5-0.9; t1 is the length of air capture that has been performed by the bifunctional material, t2 is the length of air capture that can be performed by the bifunctional material, and t3 is the conversion time of the bifunctional material. BRIEF DESCRIPTION OF DRAWINGS

[0019] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which: Figure 1 A structural schematic diagram of a system for direct air capture coupled with in-situ catalytic conversion for preparing green fuel in an embodiment of the present application is shown; Figure 2 A structural schematic diagram of a system for direct air capture coupled with in-situ catalytic conversion for preparing green fuel in another embodiment of the present application is shown; Figure 3 A flowchart of a method for direct air capture coupled with in-situ catalytic conversion for preparing green fuel according to an embodiment of the present application is shown; Figure 4 A flowchart of a method for direct air capture coupled with in-situ catalytic conversion for preparing green fuel according to another embodiment of the present application is shown.

[0020] Explanation of reference signs: 1 - Electrical energy supply and storage unit, 11 - Renewable energy power generation device, 12 - Electrical energy storage device; 2 - Gas generation and control unit, 21 - Hydrogen generator, 22 - Nitrogen generator, 23 - Air compressor, 24 - Hydrogen controller, 25 - Nitrogen controller, 26 - Air controller; 3 - Adsorption and conversion unit, 31 - Reactor; 4 - Product collection and detection unit, 41 - Detection device, 42 - Product separation device, 42' - Liquid phase product separation device, 42'' - Gas phase product separation device, 43 - One-way valve. DETAILED DESCRIPTION

[0021] Embodiments of the present application are described in detail below with reference to examples illustrated in the accompanying drawings, in which the same or similar components or components having the same or similar functions are denoted by the same or similar reference numerals throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are intended only to explain the present application, and cannot be understood as limiting the present application.

[0022] In one aspect of the present application, the present application proposes a system for directly capturing air coupled with in-situ catalytic conversion to prepare green fuel. In some embodiments of the present application, referring to Figure 1 and Figure 2 , the system for directly capturing air coupled with in-situ catalytic conversion to prepare green fuel includes an electrical energy supply and storage unit 1, a gas generation and control unit 2, an adsorption and conversion unit 3, and a product collection and detection unit 4, wherein the electrical energy supply and storage unit 1 includes a renewable energy power generation device 11 and an electrical energy storage device 12, the electrical energy supply and storage unit 1 is electrically connected to the gas generation and control unit 2, the adsorption and conversion unit 3, and the product collection and detection unit 4 respectively, and the gas generation and control unit 2, the adsorption and conversion unit 3, and the product collection and detection unit 4 are connected in sequence.

[0023] Thus, the renewable energy power generation device is used to generate electrical energy, and the electrical energy storage device is used to store the electrical energy to provide power for the entire system; the gas generation and control unit can form gases for adsorption, conversion and purging to provide the required gases for the adsorption and conversion unit; the adsorption and conversion unit can achieve the capture and direct catalytic conversion of carbon dioxide in air to produce green fuel; the product collection and detection unit is used to separate and collect the produced green fuel and detect it. The system completes the adsorption and catalytic conversion process in the same reactor, which can significantly reduce the high cost and high energy consumption of carbon dioxide compression, liquefaction and transportation in the traditional carbon capture and utilization process, and the electrical energy generated by the renewable energy source provides the required power for the system, which can provide a new method for emission reduction and carbon reduction.

[0024] In some embodiments of the present application, the renewable energy power generation device 11 can include at least one of a solar photovoltaic, a wind turbine, and a tidal energy conversion device. The above-mentioned power generation device generates electricity using renewable energy, and the green electricity produced supplies the electricity required by the entire system, which can promote emission reduction and carbon reduction.

[0025] In some specific embodiments, the renewable energy power generation device 11 can include a solar photovoltaic power generation device, which can include one or more solar panels.

[0026] In some embodiments of the present application, the electrical energy storage device 12 can include a battery. In some embodiments, the electrical energy storage device 12 can include a lithium-ion battery.

[0027] In some embodiments, the electrical energy storage device 12 can be a battery. In other embodiments, the electrical energy storage device 12 can be other electrical energy storage devices.

[0028] In some specific embodiments, the renewable energy power generation device 11 is connected to the electrical energy storage device 12, and the electrical energy storage device 12 is respectively connected to the gas generation and control unit 2, the adsorption and conversion unit 3, and the product collection and detection unit 4. The electrical energy generated by the renewable energy power generation device 11 can be stored in the electrical energy storage device, forming more stable electrical energy, which is then supplied to the entire system.

[0029] In some embodiments of the present application, referring to Figure 1 and Figure 2 , the gas generation and control unit 2 can include an air compressor 23, a hydrogen generator 21, and a nitrogen generator 22, all of which are connected to the adsorption and conversion unit 3. The air compressor 23 can provide air for adsorption to the adsorption and conversion unit, the hydrogen generator 21 can form hydrogen for carbon dioxide conversion, and the nitrogen generator 22 can form nitrogen for purging, providing a basis for the capture and direct catalytic conversion of carbon dioxide in air.

[0030] In some embodiments of the present application, the hydrogen generator 21 can use green renewable energy as energy input, produce green hydrogen as hydrogen input by means of electrolysis of water, etc., and provide gas raw materials for the preparation of low-carbon green fuel.

[0031] In some embodiments of the present application, referring to Figure 1 and Figure 2, the gas generation and control unit 2 can include an air controller 26, a hydrogen controller 24 and a nitrogen controller 25, the air controller 26 is connected with the air compressor 23 and the adsorption and conversion unit 3 respectively, the hydrogen controller 24 is connected with the hydrogen generator 21 and the adsorption and conversion unit 3 respectively, and the nitrogen controller 25 is connected with the nitrogen generator 22 and the adsorption and conversion unit 3 respectively. Each gas of the gas generation and control unit is provided with a corresponding controller, which can control whether the gas is input into the adsorption and conversion unit, and can control the flow of each gas.

[0032] In some embodiments, the hydrogen controller 24 can include a first flow control valve, the outlet of the hydrogen generator 21 is connected with the first flow control valve, and the first flow control valve can adjust the flow of hydrogen, so as to adjust the conversion rate of carbon dioxide in the adsorption and conversion unit.

[0033] In some embodiments, the hydrogen controller 24 can include a first flow control valve and a first electromagnetic valve, the first electromagnetic valve can be arranged between the hydrogen generator 21 and the first flow control valve, and the first electromagnetic valve is used for controlling the on-off of the hydrogen transmission pipeline.

[0034] In some embodiments, the nitrogen controller 25 can include a second flow control valve, the outlet of the nitrogen generator 22 is connected with the second flow control valve, and the second flow control valve can adjust the flow of nitrogen, so as to purge the inside of the adsorption and conversion unit.

[0035] In some embodiments, the nitrogen controller 25 can include a second flow control valve and a second electromagnetic valve, the second electromagnetic valve can be arranged between the nitrogen generator 22 and the second flow control valve, and the second electromagnetic valve is used for controlling the on-off of the nitrogen transmission pipeline.

[0036] In some embodiments, the air controller 26 can include a third flow control valve, the outlet of the air compressor 23 is connected with the third flow control valve, and the third flow control valve can adjust the flow of air, so as to adjust the adsorption rate of carbon dioxide in the adsorption and conversion unit.

[0037] In some embodiments, the air controller 26 can include a third flow control valve and a third electromagnetic valve, the third electromagnetic valve can be arranged between the air compressor 23 and the third flow control valve, and the third electromagnetic valve is used for controlling the on-off of the air transmission pipeline.

[0038] In some embodiments of the present application, reference is made to Figure 1 and Figure 2The adsorption and conversion unit 3 comprises a reactor 31, which can comprise a fixed bed and / or a fluidized bed, the bed of the fixed bed and / or the bed of the fluidized bed being packed with a bifunctional material having the functions of direct air capture and catalytic conversion, for realizing the capture and direct in-situ catalytic conversion of CO2 in the air, wherein the bifunctional material comprises an adsorption component and a catalytic component.

[0039] In some embodiments, the reactor 31 can be a fixed bed. In other embodiments, the reactor 31 can be a fluidized bed.

[0040] In some embodiments, the adsorption component can comprise a molecular sieve adsorbent or a solid amine adsorbent. The adsorption component can adsorb carbon dioxide in the air.

[0041] In some embodiments, the catalytic component can comprise at least one of a nickel catalyst and an iron catalyst, and the catalytic component can catalyze the conversion of carbon dioxide into green fuel.

[0042] In some embodiments, the green fuel can comprise one or more of carbon monoxide, methane, methanol, and olefins. The catalytic component can be selected and adjusted according to the type of desired product, so as to improve the conversion rate of carbon dioxide and the selectivity of the product.

[0043] In some embodiments, referring to Figure 1 The product collection and detection unit 4 can comprise a detection device 41 for detecting the product output by the adsorption and conversion unit 3, and a product separation device 42 for separating and collecting the product.

[0044] In some embodiments, referring to Figure 2 The product collection and detection unit 4 can comprise a detection device 41, a liquid product separation device 42’ for gas-liquid separation, purification and collection of liquid products, and a gas product separation device 42’’ for separation and collection of gas products.

[0045] In some embodiments, the product collection and detection unit 4 can comprise a condenser, a gas-liquid separator, and an online analysis device, the online analysis device being located between the adsorption and conversion unit and the condenser, the condenser being located at the inlet of the gas-liquid separator, and the online analysis device can comprise at least one of a gas chromatograph, a liquid chromatograph, a mass spectrometer, and a flue gas analyzer. In some embodiments, the condenser can be a serpentine condenser.

[0046] In some embodiments, referring to Figure 2The product collection and detection unit 4 and the adsorption and conversion unit 3 can be further provided with a one-way valve 43. The one-way valve 43 can prevent gas backflow, especially in the process of introducing hydrogen for the catalytic conversion of carbon dioxide. The one-way valve 43 can prevent the gas from flowing back into the adsorption and conversion unit, thereby avoiding the adverse effects of air (oxygen) on catalytic conversion.

[0047] In another aspect of the present application, the present application provides a method for directly capturing air coupled with in-situ catalytic conversion to prepare green fuel. The system described above is used for air capture and in-situ catalytic conversion. Referring to Figure 3 The method comprises the following steps: S1: The power supply and storage unit provides power for the system by converting renewable energy into electrical energy and storing it.

[0048] The power supply and storage unit can provide power for the entire system by converting at least one of renewable solar energy, wind energy, and tidal energy into electrical energy and storing it, thereby supporting the operation of the entire system.

[0049] In some embodiments, the power supply and storage unit can include a solar panel that can convert solar energy into electrical energy.

[0050] S2: Place the dual-functional material with adsorption and catalytic functions in the adsorption and conversion unit.

[0051] In some embodiments, the dual-functional material includes an adsorption component and a catalytic component. The adsorption component and the catalytic component can be physically mixed, and the mixture can be placed in the adsorption and conversion unit.

[0052] In some embodiments, the adsorption and conversion unit includes a fluidized bed or a fixed bed, and the dual-functional material can be placed in the bed layer of the fluidized bed or the fixed bed.

[0053] S3: Introduce air into the adsorption and conversion unit through the gas generation and control unit. The dual-functional material adsorbs CO2 in the air, and the air after removing CO2 is discharged from the system.

[0054] In some embodiments, air can be introduced into the adsorption and conversion unit through an air compressor, and the flow rate of the air can be adjusted through a third flow control valve. In some specific embodiments, the flow rate of the air introduced into the adsorption and conversion unit can be 200 mL / min.

[0055] S4: Introduce nitrogen into the adsorption and conversion unit through the gas generation and control unit to purge the air in the adsorption and conversion unit.

[0056] In some embodiments, nitrogen gas can be introduced into the adsorption and conversion unit through a nitrogen gas generator, and air can be purged to provide an oxygen-free environment for subsequent catalytic conversion reactions. In some embodiments, the nitrogen gas generator can produce nitrogen gas by separating air.

[0057] In some embodiments, the flow rate of nitrogen gas can be adjusted by a second flow valve. In some specific embodiments, the flow rate of nitrogen gas can be 200 mL / min.

[0058] S5: Introduce hydrogen gas into the adsorption and conversion unit through the gas generation and control unit and heat the bifunctional material, which will release the adsorbed CO2 and convert it into green fuel in situ.

[0059] In some embodiments, hydrogen gas can be introduced into the adsorption and conversion unit through a hydrogen gas generator, and the flow rate of hydrogen gas can be adjusted by a first flow control valve. In some specific embodiments, the hydrogen gas generator can produce green hydrogen by electrolyzing water, etc.

[0060] In some embodiments, the flow rate of hydrogen gas can be 0.1 L / min-10 L / min, and the pressure of hydrogen gas can be normal pressure to 5 MPa. After no nitrogen gas can be detected in the adsorption and conversion unit, the bifunctional material is heated to release the adsorbed carbon dioxide and convert it into green fuel in situ.

[0061] In some embodiments, the heating rate of the bifunctional material can be 5 ℃ / min-100 ℃ / min, for example, the heating rate can be 5 ℃ / min, 15 ℃ / min, 35 ℃ / min, 50 ℃ / min, 80 ℃ / min, 100 ℃ / min, etc.

[0062] In some embodiments, the heating temperature of the adsorption and conversion unit can be 200 ℃-300 ℃, and the reaction time can be 0.5 h-2 h. For example, the heating temperature of the adsorption and conversion unit can be 200 ℃, 230 ℃, 260 ℃, 280 ℃, 300 ℃, etc., and the reaction time can be 0.5 h, 0.7 h, 1 h, 1.5 h, 2 h, etc. Thus, the bifunctional material can release the adsorbed carbon dioxide, which reacts with hydrogen gas to generate green fuel.

[0063] In some embodiments, the green fuel includes at least one of methane, carbon monoxide, methanol, and olefins, and the product selectivity can be controlled by adjusting the loading of the catalyst (catalytic component) and the reaction temperature.

[0064] S6: Introduce the generated green fuel into the product collection and detection unit, and detect, separate and collect the obtained product.

[0065] The detection device can detect the generated green fuel, so as to know the components and contents of the product, and the product separation device is used to separate and collect the product.

[0066] S7: repeating S3-S6.

[0067] After the adsorbed carbon dioxide is converted into green fuel, S3-S6 can be repeated to continuously perform the direct carbon dioxide capture and catalytic conversion reaction.

[0068] In some embodiments of the present application, referring to Figure 4 , the method for preparing green fuel by directly capturing air and coupling in-situ catalytic conversion can include the following steps: S1: using a solar cell and storing by a lithium battery to provide power for the system; S2: loading a bifunctional material into a reactor; S3: introducing air into the reactor to perform a direct air capture process; S4: introducing nitrogen into the reactor to perform a purging process; S5: introducing hydrogen into the reactor and performing a temperature conversion process on the reactor; S6: separating, detecting and collecting the product; and S7: repeating S3-S6.

[0069] In order to realize the efficient and continuous operation of the system process, the power generation and storage of the power supply and storage unit need to be considered, and a suitable process strategy is designed.

[0070] In some embodiments of the present application, during the operation of the system, according to the real-time power generation P gen of the renewable energy power generation device, the existing storage power Q of the power supply and storage unit, the consumption power P cap of the system for direct air capture, the consumption power P con of the system for in-situ conversion, the direct air capture breakthrough time t cap of the bifunctional material, and the conversion time t con of the bifunctional material under the adsorption breakthrough condition, the subsequent process is dynamically adjusted based on the air capture time t1 of the bifunctional material.

[0071] It should be noted that the power generation of the renewable energy power generation device is different under different light conditions, for example, the power generation is higher under sufficient light conditions, and the power generation is basically 0 under night or no light conditions. The power consumption of the system for direct air capture includes the power consumption of the adsorption and conversion unit for capturing air and the power consumption of the air compressor. The power of the system for in-situ conversion can include the power consumed by the adsorption and conversion unit for catalytic conversion of carbon dioxide and the power consumed by the product collection and detection unit during in-situ conversion. For a specific type and content of bifunctional material, the direct air capture breakthrough time of the bifunctional material is a fixed value, and the time from the start of adsorption to the detection of carbon dioxide at the outlet is the direct air capture breakthrough time of the bifunctional material. The conversion time required by the bifunctional material under the adsorption breakthrough condition refers to the time required for the complete conversion of the adsorbed carbon dioxide when the bifunctional material adsorbs carbon dioxide until just reaching the breakthrough.

[0072] In some embodiments, when the process starts, the optimal capture end time and conversion time can be determined and dynamically adjusted according to the following constraint conditions: Conversion time constraint: t3= (t1+t2) / t cap ×t con Equation (1); Capture time constraint: t1+t2≤ t cap Equation (2); Energy constraint: P cap ×t2+P con ×t3≤ P gen ×(t2+t3)+η×Q Equation (3); Wherein, η is the energy surplus coefficient of the system, which is 0.5-0.9; t1 is the air capture time of the bifunctional material, t2 is the air capture time of the bifunctional material, and t3 is the conversion time of the bifunctional material. By setting the energy surplus coefficient of the system, the energy surplus of the system can be used for system standby.

[0073] Through the above constraint conditions, the power and each unit can be matched, and as much as possible the adsorbed carbon dioxide can be catalytically converted to form green fuel.

[0074] In some embodiments, when t2=0, the in-situ conversion stage is entered.

[0075] The power consumption of the system for direct air capture (P cap ), the power consumption of the system for in-situ conversion (P con ), the direct air capture breakthrough time of the bifunctional material (t cap ), and the conversion time required by the bifunctional material under the adsorption breakthrough condition (t con) need to change according to different renewable energy forms, bifunctional materials, and different green fuel products.

[0076] The present application has the following advantages: (1) direct air capture coupled with in-situ conversion can greatly reduce the desorption temperature of the direct air capture process, improve the adsorption amount and conversion rate of carbon dioxide in the treatment process, and improve the energy utilization efficiency; (2) green electricity generated by renewable energy is used as energy input, green carbon is supplied by an air compressor, and green hydrogen obtained by electrolysis of water is used as a hydrogen source, and the product is green fuel.

[0077] The present application will be described below through specific examples, and those skilled in the art can understand that the specific examples below are only for illustrative purposes and do not limit the scope of the present application in any way. In addition, in the following examples, unless otherwise specified, the materials and equipment used are commercially available. If the specific treatment conditions and methods are not explicitly described in the following examples, the conditions and methods known in the art can be used for treatment.

[0078] Example 1 In Example 1, the structure of the system for preparing green fuel by direct air capture coupled with in-situ catalytic conversion is as shown in Figure 2 The system includes an electric energy supply and storage unit 1, a gas generation and control unit 2, an adsorption and conversion unit 3, and a product collection and detection unit 4. The electric energy supply and storage unit 1 specifically includes a renewable energy power generation device 11 and an electric energy storage device 12, which are respectively used to generate electric energy by using renewable energy, store the generated electric energy, and provide the required electric power for the gas generation and control unit 2, the adsorption and conversion unit 3, and the product collection and detection unit 4. The gas generation and control unit 2 specifically includes a hydrogen generator 21, a nitrogen generator 22, an air compressor 23, a hydrogen controller 24, a nitrogen controller 25, and an air controller 26, wherein the hydrogen generator, the nitrogen generator, and the air compressor are respectively used to generate the required hydrogen, nitrogen, and air for the process, and the hydrogen controller, the nitrogen controller, and the air controller are respectively used to control the corresponding flow of gas into the reactor. The adsorption and conversion unit 3 includes a reactor 31 for carrying out direct air capture and in-situ catalytic conversion reactions. The products obtained by the reaction enter the product collection and detection unit 4, which specifically includes a detection device 41, a liquid product separation device 42', and a gas product separation device 42'', wherein the detection device 41 is used to detect the products generated by the reaction, the liquid product separation device 42' is used for gas-liquid separation and purification and collection of liquid products, and the gas product separation device 42'' is used to separate the gas phase products in the products.

[0079] The renewable energy power generation device used in this embodiment is a solar photovoltaic power generation device, and a total of 5 solar panels are used, each with a power generation power of 600 W and an output voltage of 48 V. The electric energy storage device used in this embodiment is a lithium ion battery, which has a maximum output power of 8 kW and a maximum capacity of 10 kWh.

[0080] The gas generation device used in this embodiment includes a hydrogen generator, a nitrogen generator, and an air compressor. The hydrogen generator generates green hydrogen by electrolyzing water, with a maximum hydrogen production rate of 1 L / min. The nitrogen generator supplies nitrogen by separating air, with a maximum nitrogen production rate of 1 L / min. The air compressor can compress air into a gas storage tank and form a high-pressure air flow, where the gas storage tank has a volume of 18 L and a maximum pressure of 0.8 MPa.

[0081] Three flow controllers are used in this embodiment to control the flow rate of the three air streams, and solenoid valves are used to control the flow of corresponding air into the reactor.

[0082] The adsorption and conversion unit in this embodiment uses a fixed bed (reactor) with an inner diameter of 30 mm and an outer diameter of 35 mm. An electric heating furnace is used to heat the fixed bed in this embodiment.

[0083] Anhydrous calcium chloride is used as a drying agent to dry the water in the product, and a flue gas analyzer is used as an online analysis device for gas phase products in this embodiment.

[0084] The method for directly capturing air coupled with in-situ catalytic conversion to prepare green fuel proposed in this embodiment uses the above system to prepare green fuel, including the following steps: S1: The electric energy supply and storage unit generates electricity through solar power and stores it through lithium batteries to provide power for the system; S2: A dual-functional material with both adsorption and catalytic functions is loaded into the adsorption and conversion unit; S3: Air is introduced into the adsorption and conversion unit through the gas generation and control unit, and the dual-functional material adsorbs CO2 in the air. The CO2-free air is discharged through the exhaust port; S4: Nitrogen is introduced into the adsorption and conversion unit through the gas generation and control unit for purging, and the purged gas is discharged through the exhaust port; S5: Hydrogen is introduced into the adsorption and conversion unit through the gas generation and control unit, the hydrogen pressure and flow rate are adjusted, and the adsorption and conversion unit is heated to 200°C. The adsorbed CO2 reacts with hydrogen to generate green fuel methane; S6: The generated green fuel methane is introduced into the product collection and detection unit for detection and collection; S7: Steps S3 to S6 are repeated to achieve continuous production.

[0085] In this embodiment, the bifunctional material used is a combination of a molecular sieve adsorbent and a nickel catalyst, with a ratio of 1:1 between the molecular sieve adsorbent and the nickel catalyst, and is filled by physical mixing and filling. In this embodiment, the flow rate of air introduced into the reactor is 200 mL / min.

[0086] In this embodiment, after direct air capture is completed, the reactor is purged with 200 mL / min of nitrogen to purge oxygen in the reactor.

[0087] In this embodiment, the flow rate of hydrogen introduced into the reactor is 100 mL / min, and the pressure of hydrogen is atmospheric pressure. After nitrogen can no longer be detected in the reactor, the reactor is heated at a heating rate of 50°C / min.

[0088] In this embodiment, the renewable energy source is solar energy, and its power generation is P gen =1000 W (daytime) and P gen =0 (nighttime). The rated power consumption of the system P run =0.8 kW, the power consumption of the system for direct air capture P cap =1 kW, the power consumption of the system for in-situ conversion P con =2 kW, the direct air capture breakthrough time t cap of the bifunctional material is 10 hours, and the conversion time t con required by the bifunctional material under adsorption breakthrough conditions is 0.5 hours.

[0089] When the direct air capture process starts, the optimal capture end time and conversion time are determined and dynamically adjusted according to the following conditions: Objective: max(t2); Conversion time constraint: t3= (t1+t2) / t cap ×t con ; Time constraint: t1+t2≤ t cap ; Energy constraint: P cap ×t2+P con ×t3≤ P gen ×(t2+t3)+η×Q; wherein η is the energy surplus coefficient of the system; t1 is the air capture time already performed by the bifunctional material, t2 is the air capture time that can still be performed by the bifunctional material, and t3 is the conversion time of the bifunctional material. In this embodiment, η is 0.7.

[0090] In this embodiment, the reaction product is green fuel methane, which also includes unreacted hydrogen and CO2.

[0091] In this embodiment, the system of direct air capture coupled with in-situ catalytic conversion to produce green fuel is able to achieve a direct air capture adsorption capacity of 0.21 mmol / g of zeolite, a CO2 conversion rate of 80%, and a methane selectivity of 100%.

[0092] Embodiment 2 In this embodiment, the bifunctional material used is a combination of a zeolite adsorbent and a nickel catalyst, and the rest of the conditions are exactly the same as in Embodiment 1.

[0093] In this embodiment, the reaction product is green fuel carbon monoxide, which also includes unreacted hydrogen and CO2.

[0094] In this embodiment, the system of direct air capture coupled with in-situ catalytic conversion to produce green fuel is able to achieve a direct air capture adsorption capacity of 0.20 mmol / g of zeolite, a CO2 conversion rate of 60%, and a carbon monoxide selectivity of 80%, and the rest is methane.

[0095] Embodiment 3 In this embodiment, the bifunctional material used is a combination of a solid amine adsorbent and a nickel catalyst, and the rest of the conditions are exactly the same as in Embodiment 1.

[0096] In this embodiment, the reaction product is green fuel methane, which also includes unreacted hydrogen and CO2.

[0097] In this embodiment, the system of direct air capture coupled with in-situ catalytic conversion to produce green fuel is able to achieve a direct air capture adsorption capacity of 0.6 mmol / g of zeolite, a CO2 conversion rate of 65%, and a methane selectivity of 100%.

[0098] In the description of the present specification, the description referring to the terms "one embodiment", "another embodiment", and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment are included in at least one embodiment of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples, without contradiction. In addition, it should be noted that in the present specification, the terms "first", "second", "third" are for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0099] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that variations, modifications, substitutions and changes can be made by those skilled in the art without departing from the scope of the present application.

Claims

1. A system for producing green fuels by direct air capture coupled with in-situ catalytic conversion, characterized in that, include: The system includes an energy supply and storage unit, a gas generation and control unit, an adsorption and conversion unit, and a product collection and detection unit. The energy supply and storage unit includes a renewable energy power generation device and an energy storage device. The energy supply and storage unit is electrically connected to the gas generation and control unit, the adsorption and conversion unit, and the product collection and detection unit, respectively. The gas generation and control unit, the adsorption and conversion unit, and the product collection and detection unit are connected in sequence.

2. The system according to claim 1, characterized in that, The renewable energy power generation device includes at least one of solar photovoltaic, wind turbine, and tidal energy conversion device; And / or, the energy storage device includes a battery.

3. The system according to claim 1, characterized in that, The gas generation and control unit includes an air compressor, a hydrogen generator, and a nitrogen generator, all of which are connected to the adsorption and conversion unit.

4. The system according to claim 3, characterized in that, The gas generation and control unit includes an air controller, a hydrogen controller, and a nitrogen controller. The air controller is connected to the air compressor and the adsorption and conversion unit, respectively. The hydrogen controller is connected to the hydrogen generator and the adsorption and conversion unit, respectively. The nitrogen controller is connected to the nitrogen generator and the adsorption and conversion unit, respectively.

5. The system according to claim 1, characterized in that, The adsorption and conversion unit includes a fixed bed and / or a fluidized bed. The bed of the fixed bed and / or the bed of the fluidized bed are filled with a bifunctional material with direct air capture and catalytic functions to achieve the capture and direct in-situ catalytic conversion of CO2 in the air. The bifunctional material includes an adsorption component and a catalytic component.

6. The system according to claim 1, characterized in that, The product collection and detection unit is used to detect the product and separate and collect it. And / or, the green fuel includes one or more of carbon monoxide, methane, methanol, and olefins.

7. The system according to any one of claims 1-6, characterized in that, The product collection and detection unit includes a condenser, a gas-liquid separator, and an online analysis device. The condenser is located at the inlet of the gas-liquid separator, and the online analysis device includes at least one of a gas chromatograph, a liquid chromatograph, a mass spectrometer, and a flue gas analyzer.

8. A method for preparing green fuels by direct air capture coupled with in-situ catalytic conversion, characterized in that, Using the system of any one of claims 1-7 for air capture and in-situ catalytic conversion includes the following steps: S1: The power supply and storage unit provides power to the system by converting renewable energy into electrical energy and storing it; S2: Place a dual-functional material with both adsorption and catalysis functions in the adsorption and conversion unit; S3: Air is introduced into the adsorption and conversion unit through the gas generation and control unit. The bifunctional material adsorbs CO2 in the air and the air after CO2 removal is discharged from the system. S4: Nitrogen gas is introduced into the adsorption and conversion unit through the gas generation and control unit to purge the air in the adsorption and conversion unit; S5: Hydrogen gas is introduced into the adsorption and conversion unit through the gas generation and control unit and the bifunctional material is heated. The bifunctional material will release the adsorbed CO2 and convert it into green fuel in situ. S6: Pass the generated green fuel into the product collection and detection unit to detect, separate and collect the obtained product; S7: Repeat S3-S6.

9. The method according to claim 8, characterized in that, During system operation, the power generation P of the renewable energy power generation device is calculated in real time. gen Combined with the existing stored power Q of the power supply and storage unit, the power consumed by the system for direct air capture is P. cap The power consumed by the system for in-situ conversion, P con Breakthrough time t for direct air capture of bifunctional materials cap The conversion time t required for bifunctional materials under adsorption breakthrough conditions con The subsequent process is dynamically adjusted based on the air capture time t1 already achieved using bifunctional materials.

10. The method according to claim 9, characterized in that, The optimal capture end time and conversion time are determined and dynamically adjusted based on the following constraints: Transformation time constraint: t3 = (t1+t2) / t cap ×t con Equation (1); Capture time constraint: t1 + t2 ≤ t cap Equation (2); Energy constraint: P cap ×t2+P con ×t3≤ P gen ×(t2+t3)+η×Q Equation (3); Where η is the energy surplus coefficient of the system, which is taken as 0.5-0.9; t1 is the air capture time that the bifunctional material has already carried out; t2 is the air capture time that the bifunctional material can still carry out; and t3 is the conversion time of the bifunctional material.

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