System and method for variable temperature co2 capture and in situ conversion driven by electromagnetic induction heating

Abstract

The application belongs to the technical field of carbon capture and utilization, and discloses a system and method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating, which comprises a pretreatment unit, a carbon capture-in-situ conversion integrated unit, a waste heat recovery unit and a separation-purification unit, and the carbon capture-in-situ conversion integrated unit is provided with an electromagnetic induction heating device; the carbon capture-in-situ conversion integrated unit comprises at least two reactors, which are multi-stage parallel electromagnetic induction fixed bed reactors or circulating electromagnetic induction fluidized bed reactors; the inside of the reactors is filled with multifunctional composite materials. The multifunctional composite materials with high magnetic heat performance, high adsorption capacity and high catalytic activity are used together with an alternating magnetic field to realize direct capture of CO2 in low-temperature flue gas or air and in-situ high-temperature catalytic conversion of the CO2 into high-value-added chemicals such as methane, synthetic gas and olefins, thereby improving the conversion rate and product selectivity.

Description

Technical Field

[0001] This invention belongs to the field of carbon capture and utilization technology, specifically, it relates to a system and method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating. Background Technology

[0002] Currently, carbon dioxide capture, utilization, and storage (CCUS) is a crucial technology for ensuring the large-scale low-carbon utilization of traditional fossil fuels. However, traditional CCUS technologies suffer from high energy consumption, high cost, and low efficiency, significantly hindering their promotion and application. In recent years, new CO2 capture and in-situ conversion technologies have emerged. By coupling the CO2 capture process with the conversion process in the same reactor, CO2 can be directly converted into high-value-added products, avoiding the energy-intensive subsequent complex processes such as CO2 desorption, purification, compression, and transportation, thus significantly reducing the overall cost and energy consumption. However, due to the high bond energy of the C=O double bond in the CO2 molecule, it is thermodynamically very stable, often requiring activation and conversion under harsh conditions such as high temperature and high pressure. Furthermore, most industrial flue gas is currently equipped with heat exchange systems to fully utilize waste heat for energy saving and consumption reduction. After denitrification and desulfurization, the flue gas temperature is usually low (<150℃), and the CO2 concentration is low, creating a temperature mismatch problem between low-temperature flue gas CO2 capture and high-temperature in-situ conversion processes.

[0003] To match the reaction temperatures of CO2 adsorption and conversion, domestic and international research mainly focuses on medium- and high-temperature CO2 capture and in-situ conversion to produce chemicals such as methane, syngas, and olefins, achieving isothermal (200–800°C) capture and conversion. For example, CN112569739 A discloses a system and method for isothermal capture and in-situ conversion of carbon dioxide into syngas, requiring a reaction temperature of 600–800°C; CN 117123229A discloses an oxygen-resistant nickel-based bifunctional material that achieves carbon dioxide capture and in-situ hydrogenation conversion of oxygen-containing flue gas into methane under isothermal conditions of 200–350°C. Under current technology, the above processes all employ traditional heating methods (electric heating or fuel combustion heating). Due to the high-temperature reaction conditions, traditional heating methods first heat the reactor wall or internal heating components through an external heat source (electric heating or combustion heating) before transferring the heat to the materials. This results in uneven reactor heating, slow heating / cooling processes, and low energy utilization efficiency. Furthermore, it cannot achieve the coupling of low-temperature CO2 capture and high-temperature conversion through rapid and precise temperature changes, meaning that low-temperature flue gas must be heated to the required high temperature before capture and conversion can occur, leading to enormous energy consumption. Therefore, how to achieve in-situ high-temperature conversion of low-temperature flue gas CO2 capture into high-value-added chemicals such as methane, syngas, and olefins through precise and rapid temperature changes is a key issue in overcoming the high energy consumption and high cost bottlenecks of existing low-temperature CO2 capture and conversion technologies. Electromagnetic induction heating technology, as a non-direct contact heating technology that directly converts electromagnetic energy into heat energy, rapidly generates heat directly induction on magnetic materials. This eliminates the problems of slow heating / cooling rates, uneven heating, difficult temperature control, and low energy efficiency associated with traditional contact heating methods, improving energy transfer efficiency and heat dissipation. Electromagnetic induction heating is 30%–50% more efficient than flame furnaces and 20%–30% more efficient than resistance furnaces. It can also be combined with green electricity generated from renewable energy sources to achieve energy-saving electrification of production processes. For example, CN 119461243 A discloses a method for capturing and converting green CO2 into syngas using electromagnetic induction heat. This method utilizes Co-based / CaO-based / Fe-based multifunctional materials to simultaneously achieve CO2 capture and in-situ conversion under isothermal conditions of 600–700℃. However, this method employs isothermal operation, requiring the flue gas to undergo CO2 adsorption and conversion simultaneously at a high temperature of 600–700℃. For most low-temperature flue gas below 150℃, it is necessary to preheat the flue gas to above 600℃, which not only leads to significant additional energy consumption but also fails to fully utilize the complementary advantages of favorable low-temperature adsorption thermodynamics and high-temperature conversion kinetics for CO2. Furthermore, this method only produces syngas (CO+H2), resulting in a single product type. Therefore, how to utilize the rapid and precise temperature-changing characteristics of electromagnetic induction heating to overcome the temperature mismatch problem between low-temperature flue gas CO2 capture and high-temperature in-situ conversion, while expanding product diversity, remains a key technical problem that has not yet been solved. Summary of the Invention

[0004] The purpose of this invention is to overcome the deficiencies in the prior art and provide a system and method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating. The invention designs a multifunctional composite material with high magnetocaloric performance, high adsorption capacity and high catalytic activity. Through the synergistic effect of the multifunctional composite material and the alternating magnetic field, CO2 in low-temperature flue gas or air is directly captured and converted into high-value-added chemicals such as methane, syngas, and olefins in in-situ at high temperature, thereby significantly reducing process energy consumption and cost.

[0005] The objective of this invention can be achieved through the following technical solutions: This invention provides a system for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating, comprising a pretreatment unit, an integrated carbon capture-in-situ conversion unit, a waste heat recovery unit, and a separation-purification unit. The integrated carbon capture-in-situ conversion unit is equipped with an electromagnetic induction heating device for induction heating. The integrated carbon capture-in-situ conversion unit includes at least two reactors, which are multi-stage parallel electromagnetic induction fixed-bed reactors or circulating electromagnetic induction fluidized-bed reactors. The interior of each reactor is filled with a multifunctional composite material, which contains magnetic components, adsorption components, and conversion components.

[0006] In some embodiments of the present invention, when the reactor is a multi-stage parallel electromagnetic induction fixed-bed reactor: The electromagnetic induction heating driven variable temperature carbon dioxide capture and in-situ conversion system of the present invention includes: a pretreatment unit, an integrated carbon capture-in-situ conversion unit, a waste heat recovery unit, and a separation-purification unit. The integrated carbon capture-in-situ conversion unit is equipped with an electromagnetic induction heating device for induction heating. The pretreatment unit includes an electrostatic dust removal device, a primary temperature control panel, and a secondary temperature control panel; The integrated carbon capture-in-situ conversion unit includes two reactors, specifically a first fixed-bed reactor and a second fixed-bed reactor. The integrated carbon capture-in-situ conversion unit completes the adsorption and capture and in-situ conversion of carbon dioxide under variable temperature conditions where the adsorption reaction temperature and the conversion reaction temperature are different. The waste heat recovery unit includes an industrial chiller and a heat exchanger; the industrial chiller includes, but is not limited to, any one of water-cooled, air-cooled and evaporative chillers, which exchange heat with the electromagnetic induction heating device through a cooling circulation mechanism to absorb the heat generated by the power supply. The separation and purification unit includes a condensation device and a separation device, used to condense and separate the product gas to obtain the target product; further, the separation device is preferably a pressure swing adsorption device. The inlet of the first fixed-bed reactor is connected to the outlet of the primary temperature control plate, and the inlet of the second fixed-bed reactor is connected to the outlet of the secondary temperature control plate; the outlet of the first fixed-bed reactor is connected to the inlet of the heat exchanger, and the outlet of the second fixed-bed reactor is connected to the inlet of the separation-purification unit.

[0007] Furthermore, several flow control valves are installed on the connecting pipelines between the pretreatment unit, the carbon capture-in-situ conversion integrated unit, the waste heat recovery unit, and the separation-purification unit to control the material flow direction and process switching.

[0008] Further, the magnetic component is selected from any one or more combinations of Fe, Co, Ni, Gd, Dy, Ho, Er, Tm, FeCo, FeNi, NiCo, NiFe2O4, CoFe2O4, MnFe2O4, and Fe3O4; the adsorption component is selected from any one or more combinations of carbon-based materials, zeolites, molecular sieves, metal-organic framework materials, solid amines, alkali metal oxides, alkali metal carbonates, magnesium oxide, and hydrotalcite-like derivatized adsorbents; the conversion component is selected from any one or more combinations of Ni, Ru, Co, Fe, La, Ce, Mn, Cu, Rh, Pt, Pd, Ir, Sr, Cr, Ca, Zn, Sn, V, and Ge. Furthermore, the magnetic component has a mass percentage of 0.1% to 60% in the multifunctional composite material; the adsorption component has a mass percentage of 0.1% to 80% in the multifunctional composite material; and the catalytic component has a mass percentage of 0.1% to 20% in the multifunctional composite material.

[0009] Preferably, the magnetic component accounts for 20% to 50% of the mass percentage in the multifunctional composite material; the adsorption component accounts for 40% to 80% of the mass percentage in the multifunctional composite material; and the conversion component accounts for 0.1% to 10% of the mass percentage in the multifunctional composite material.

[0010] Preferably, the multifunctional composite material can be prepared by any one or more combinations of simple physical mixing, impregnation, sol-gel method and co-precipitation method.

[0011] More preferably, the magnetic component and the conversion component in the multifunctional composite material are the same; more preferably, the magnetic component and the conversion component in the multifunctional composite material are different.

[0012] Furthermore, the electromagnetic induction heating device includes an induction heating power supply and an induction heating coil; wherein, The induction heating power supply is selected from any one of low-frequency induction heating power supply, medium-frequency induction heating power supply, high-frequency induction heating power supply and ultra-high-frequency induction heating power supply; preferably, the induction heating power supply is an ultra-high-frequency induction heating power supply. The induction coil is a multi-turn spiral coil, which is wrapped around the outside of the reactor or located in the hollow cavity formed by the inner and outer tubes. It forms an alternating magnetic field inside the electromagnetic induction heating device, realizing the conversion of electrical energy into magnetic energy, and transmitting it to the multifunctional composite material in the reactor, thereby realizing the direct heating of the interior of the multifunctional composite material and realizing the conversion of magnetic energy into thermal energy.

[0013] Furthermore, the induction heating power supply inlet is connected to an industrial chiller.

[0014] Preferably, the material of the induction heating coil is any one of pure copper, red copper, silver alloy, nickel alloy, high-temperature alloy steel nickel-aluminum alloy, nickel-silicon alloy, platinum-containing alloy, palladium-containing alloy, and Litz wire; more preferably, the number of turns of the induction heating coil is 2 to 10, and the material is preferably red copper.

[0015] Furthermore, the induction heating power supply has two control modes: constant current and constant power; wherein: When the constant current control mode is selected, the heating power and heating speed will change with the temperature of the workpiece. For ferromagnetic materials, the heating speed increases and the heating power decreases when the material is cold due to its high permeability and low equivalent impedance. When the material is hot above 600℃, the equivalent impedance increases due to the change in magnetism, the heating speed decreases and the heating power decreases. When the constant power control mode is selected, the power output of the equipment remains constant. Regardless of whether the workpiece is cold or hot, magnetic or non-magnetic, the equipment maintains a constant output power, which ensures that the heating power remains basically unchanged. This allows for a higher heating rate during the hot phase, which is beneficial for obtaining higher heating temperatures.

[0016] As an alternative implementation method, when the reactor is a circulating electromagnetic induction fluidized bed reactor: The difference between the system and the reactor used when it is a multi-stage parallel electromagnetic induction fixed bed reactor is that the integrated carbon capture-in-situ conversion unit includes two reactors and two cyclone separators, specifically including a first fluidized bed reactor and a second fluidized bed reactor, which are respectively connected to the first cyclone separator and the second cyclone separator. The integrated carbon capture-in-situ conversion unit completes the adsorption capture and in-situ conversion of carbon dioxide under variable temperature conditions where the adsorption reaction temperature and the conversion reaction temperature are different. The inlet of the first fluidized bed reactor is connected to the outlet of the primary temperature control plate, and the inlet of the second fluidized bed reactor is connected to the outlet of the secondary temperature control plate. The outlet of the first fluidized bed reactor is connected to a first cyclone separator and is connected to the inlet of the heat exchanger. The outlet of the second fluidized bed reactor is connected to a second cyclone separator and is connected to the inlet of the separation-purification unit.

[0017] Another aspect of the present invention provides a method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating, comprising the following steps: S1. Induced activation of multifunctional composite materials: A reducing gas is introduced into the carbon capture-in-situ conversion integrated unit to reduce the catalytic components in the multifunctional composite materials into metal active sites; S2, Air / Flue Gas Pretreatment: The air or industrial flue gas input into the system is passed into the pretreatment unit for dust removal and temperature control, so that the temperature of the air or industrial flue gas matches the adsorption reaction temperature. S3. Carbon dioxide capture: Pretreated air or industrial flue gas is introduced into the reactor, and the electromagnetic induction heating device is started. By adjusting the power or current of the induction heating power supply, the reactor temperature is maintained at a constant adsorption reaction temperature. After adsorption treatment by multifunctional composite materials, low-temperature adsorption and capture of carbon dioxide is achieved. The decarbonized gas after adsorption treatment is discharged after waste heat is recovered by a heat exchanger. S4. In-situ conversion of adsorbed carbon dioxide: Start the electromagnetic induction heating device, and adjust the power or current of the induction heating power supply to raise the temperature of the reactor after adsorption saturation to the conversion reaction temperature and keep the temperature constant. Then, introduce reducing gas into the reactor. Under the synergistic effect of the catalysis of the multifunctional composite material and the alternating magnetic field, the captured carbon dioxide is converted in-situ to generate product gas containing the target product. S5. Product Gas Separation and Purification: The product gas is passed into the separation and purification unit, and the target product is collected after condensation and separation. The reactor can be a fixed-bed reactor or a fluidized-bed reactor. When a fixed-bed reactor is selected, two fixed-bed reactors are used to alternately perform carbon dioxide adsorption and capture and in-situ conversion. When a fluidized-bed reactor is selected, two fluidized-bed reactors are used, and a cyclone separator is used to realize the circulation transfer of the multifunctional composite material between the two fluidized-bed reactors.

[0018] In some embodiments of the present invention, the reaction temperature of the integrated carbon capture-in-situ conversion unit is 25–800°C, the adsorption reaction temperature is 25–300°C, and the conversion reaction temperature is 25–800°C.

[0019] In some embodiments of the present invention, the current range of the adsorption reaction in step S3 is 0 to 100 A; the power range of the adsorption reaction is 10 W to 50 KW.

[0020] More preferably, the current range of the adsorption reaction in step S3 is 0 to 80 A, and the power range of the adsorption reaction is 10 W to 10 KW.

[0021] In some embodiments of the present invention, the current range of the conversion reaction in step S4 is 0 to 200A, and the power range of the conversion reaction is 10W to 100KW.

[0022] More preferably, the current range of the conversion reaction in step S4 is 0 to 100A, and the power range of the conversion reaction is 10W to 20KW.

[0023] Further, the reaction pressure of the integrated carbon capture-in-situ conversion unit is 0.01 to 5 MPa; preferably, the reaction pressure of the integrated carbon capture-conversion unit is 0.1 to 0.5 MPa.

[0024] Further, the carbon dioxide in the integrated carbon capture-in-situ conversion unit is carbon dioxide from air or industrial flue gas; preferably, the carbon dioxide content in the air or industrial flue gas is 0.01 to 90 vol; more preferably, the carbon dioxide content in the air or industrial flue gas is 0.04 to 30 vol; even more preferably, the carbon dioxide content in the air or industrial flue gas is 0.04 to 20 vol.

[0025] More preferably, the temperature of the air or industrial flue gas is 0–300°C; more preferably, the temperature of the air or industrial flue gas is 25–150°C.

[0026] In some embodiments of the present invention, the reducing gas is selected from any one or more of hydrogen, methane, ethane, and propane.

[0027] Further, the activation time of the multifunctional composite material is 1 min to 10 h; preferably, the activation time of the multifunctional composite material is 30 min to 3 h.

[0028] Compared with the prior art, the present invention has the following outstanding advantages: 1. Compared to traditional heating, electromagnetic induction heating generates heat internally, offering advantages such as non-contact energy supply, low heat loss, rapid heating rate, and uniform temperature, preventing thermal degradation of adsorbed components and sintering of catalytic components due to localized overheating. This invention leverages the rapid and precise temperature-changing characteristics of electromagnetic induction heating technology to place low-temperature CO2 adsorption (25–300℃) and high-temperature conversion (25–800℃) within their respective thermodynamically / kinetically optimal temperature windows, effectively resolving the temperature mismatch between low-temperature flue gas CO2 capture and high-temperature in-situ conversion. Simultaneously, the rapid heating rate of electromagnetic induction heating matches the periodic temperature changes required by the variable-temperature adsorption-catalysis cycle, effectively shortening the adsorption-regeneration time and significantly improving the efficiency of the variable-temperature CO2 capture and in-situ conversion system, resulting in higher economic benefits.

[0029] 2. This invention reveals the synergistic promoting effect of alternating magnetic fields on catalytic reactions. On the one hand, alternating magnetic fields exhibit a skin effect—the current distribution inside the conductor is uneven, with the current density being highest at the conductor surface and decreasing exponentially with increasing conductor depth. This enhances the surface electron density of the catalytic metal sites in the multifunctional composite material, promoting the in-situ adsorption and activation of CO2. On the other hand, the non-thermal coupling effect between the alternating magnetic field and the catalytically active sites may alter surface reaction kinetics, promoting hydrogen overflow at lower temperatures, which is beneficial for the in-situ catalytic hydrogenation of CO2. Traditional heating only provides heat and has no additional promoting effect on the reaction itself. Therefore, electromagnetic induction heating has a synergistic effect on improving the efficiency of in-situ carbon dioxide hydrogenation.

[0030] 3. This invention, through variable temperature operation and flexible selection of various reducing gases, can control the target product type and achieve diversified product output from methane and syngas to olefins (ethylene / propylene). Attached Figure Description

[0031] Figure 1 A schematic diagram of a system for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating; Figure 2 This is a schematic diagram of a system for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating based on a multi-stage parallel electromagnetic induction fixed-bed reactor. Figure 3 This is a schematic diagram of a system for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating based on a circulating electromagnetic induction fluidized bed reactor.

[0032] Drawing number explanation: 1-Electrostatic dust removal device; 21-Primary temperature control panel; 22-Secondary temperature control panel; 3-Reactor; 4-Cyclone separator; 5-Electromagnetic induction heating device; 51-Induction heating power supply; 52-Induction heating coil; 6-Industrial chiller; 7-Heat exchanger; 8-Condensation device; 9-Separation device; 31-First fixed-bed reactor; 32-Second fixed-bed reactor; 33-First fluidized-bed reactor; 34-Second fluidized-bed reactor; 4-Cyclone separator; 41-First cyclone separator; 42-Second cyclone separator. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0034] In this invention, "variable temperature" refers to a difference between the traditional carbon dioxide capture technology, which involves simultaneous capture and conversion at a single constant temperature (isothermal), and the adsorption reaction temperature (low-temperature zone) and conversion reaction temperature (high-temperature zone) of this invention are different. Electromagnetic induction heating technology is used to achieve rapid switching between these two temperature ranges. Specifically, the adsorption temperature can be understood as a temperature in the range of 25–300°C, and the conversion temperature can be understood as a temperature in the range of 25–800°C.

[0035] In this invention, before the adsorbent component in the multifunctional composite material is used for low-concentration carbon dioxide capture and in-situ conversion, the amount of carbon dioxide adsorbed by the material is detected by chromatography and calculated using the following formula: CO2 adsorption capacity (%) = in, The duration of the capture process, For the quality of the filled sample.

[0036] Work system process and operating mechanism: like Figure 1 As shown, the electromagnetic induction heating driven variable temperature carbon dioxide capture and in-situ conversion system of this application includes: a pretreatment unit, an integrated carbon capture-in-situ conversion unit, a waste heat recovery unit, and a separation-purification unit. The integrated carbon capture-in-situ conversion unit is equipped with an electromagnetic induction heating device for induction heating. The integrated carbon capture-in-situ conversion unit includes at least two reactors, which are multi-stage parallel electromagnetic induction fixed-bed reactors or circulating electromagnetic induction fluidized-bed reactors. The interior of each reactor is filled with a multifunctional composite material, which contains magnetic components, adsorption components, and conversion components.

[0037] When the system is running, reducing gas is introduced into the integrated carbon capture-in-situ conversion unit to induce activation of the multifunctional composite material. Simultaneously, the carbon emission source (air / industrial flue gas) input to the pretreatment unit is pretreated. The pretreated air or industrial flue gas then enters the integrated carbon capture-in-situ conversion unit for adsorption and conversion reactions. The decarbonized gas is directly discharged after passing through a heat exchanger in the waste heat recovery unit. Meanwhile, the captured carbon dioxide is in-situ converted into product gas containing the target product under the synergistic effect of the reducing gas, the multifunctional composite material, and the alternating magnetic field. The product gas then sequentially enters the separation-purification unit to collect the target product. During this process, the heat exchanger in the waste heat recovery unit absorbs the waste heat from the decarbonized gas and returns it to the pretreatment unit via a heat transfer medium for preheating the subsequent reducing gas, thus improving energy utilization.

[0038] In this process, the alternating magnetic field not only provides the reaction heat required for the conversion through magnetic components, but its skin effect also enhances the electron density on the surface of the catalytic metal sites, promoting CO2 activation. Simultaneously, the polarized electric field drives proton migration and promotes hydrogen overflow, achieving efficient CO2 hydrogenation at relatively low temperatures. This creates a synergistic enhancement effect between the magnetic field and catalysis. The resulting high-temperature product gas is then condensed to remove condensable components and separated by pressure swing adsorption to obtain the target product. This invention utilizes rapid and precise temperature control through electromagnetic induction heating, placing low-temperature CO2 adsorption and capture and high-temperature in-situ conversion within their respective thermodynamically and kinetically optimal temperature windows. This effectively resolves the temperature mismatch between low-temperature flue gas CO2 capture and high-temperature conversion. Furthermore, the waste heat recovery unit enables cascaded utilization of energy within the system, significantly reducing overall energy consumption.

[0039] Example 1: The reactor is a multi-stage parallel electromagnetic induction fixed-bed reactor. 1.1 Electromagnetic Induction Heating Driven Variable Temperature Carbon Dioxide Capture and In-situ Conversion System The electromagnetic induction heating-driven variable-temperature carbon dioxide capture and in-situ conversion system of this embodiment is as follows: Figures 1-2 As shown, the system includes a pretreatment unit, a carbon capture-in-situ conversion integrated unit, a waste heat recovery unit, and a separation-purification unit. The carbon capture-in-situ conversion integrated unit is equipped with an electromagnetic induction heating device 5 for induction heating. The pretreatment unit includes an electrostatic dust removal device 1, a primary temperature control plate 21, and a secondary temperature control plate 22; The integrated carbon capture-in-situ conversion unit includes two reactors 3, specifically a first fixed-bed reactor 31 and a second fixed-bed reactor 32. The integrated carbon capture-in-situ conversion unit completes the adsorption capture and in-situ conversion of carbon dioxide under variable temperature conditions where the adsorption reaction temperature and the conversion reaction temperature are different. The waste heat recovery unit includes an industrial chiller 6 and a heat exchanger 7; the industrial chiller 6 includes, but is not limited to, any one of water-cooled, air-cooled and evaporative chillers, which exchanges heat with the electromagnetic induction heating device 5 through a cooling circulation mechanism to absorb the heat generated by the power supply. The separation and purification unit includes a condenser 8 and a separation device 9, used to condense and separate the product gas to obtain the target product; further, the separation device 9 is preferably a pressure swing adsorption device. The inlet of the first fixed-bed reactor 31 is connected to the outlet of the primary temperature control plate 21, and the inlet of the second fixed-bed reactor 32 is connected to the outlet of the secondary temperature control plate 22; the outlet of the first fixed-bed reactor 31 is connected to the inlet of the heat exchanger 7, and the outlet of the second fixed-bed reactor 32 is connected to the inlet of the separation-purification unit.

[0040] Furthermore, several flow control valves are installed on the connecting pipelines between the pretreatment unit, the carbon capture-in-situ conversion integrated unit, the waste heat recovery unit, and the separation-purification unit to control the material flow direction and process switching.

[0041] Further, the magnetic component is selected from any one or more combinations of Fe, Co, Ni, Gd, Dy, Ho, Er, Tm, FeCo, FeNi, NiCo, NiFe2O4, CoFe2O4, MnFe2O4, and Fe3O4; the adsorption component is selected from any one or more combinations of carbon-based materials, zeolites, molecular sieves, metal-organic framework materials, solid amines, alkali metal oxides, alkali metal carbonates, magnesium oxide, and hydrotalcite-like derivatized adsorbents; the conversion component is selected from any one or more combinations of Ni, Ru, Co, Fe, La, Ce, Mn, Cu, Rh, Pt, Pd, Ir, Sr, Cr, Ca, Zn, Sn, V, and Ge. Furthermore, the magnetic component has a mass percentage of 0.1% to 60% in the multifunctional composite material; the adsorption component has a mass percentage of 0.1% to 80% in the multifunctional composite material; and the catalytic component has a mass percentage of 0.1% to 20% in the multifunctional composite material.

[0042] Preferably, the magnetic component accounts for 20% to 50% of the mass percentage in the multifunctional composite material; the adsorption component accounts for 40% to 80% of the mass percentage in the multifunctional composite material; and the conversion component accounts for 0.1% to 10% of the mass percentage in the multifunctional composite material.

[0043] Preferably, the multifunctional composite material can be prepared by any one or more combinations of simple physical mixing, impregnation, sol-gel method and co-precipitation method.

[0044] More preferably, the magnetic component and the conversion component in the multifunctional composite material are the same; more preferably, the magnetic component and the conversion component in the multifunctional composite material are different.

[0045] Furthermore, the electromagnetic induction heating device 5 includes an induction heating power supply 51 and an induction heating coil 52; wherein, The induction heating power supply 51 is selected from any one of low-frequency induction heating power supply, medium-frequency induction heating power supply, high-frequency induction heating power supply and ultra-high-frequency induction heating power supply; preferably, the induction heating power supply is an ultra-high-frequency induction heating power supply. The induction coil 52 is a multi-turn spiral coil, which is wrapped around the outside of the reactor or located in the hollow cavity formed by the inner and outer tubes. It forms an alternating magnetic field inside the electromagnetic induction heating device, realizing the conversion of electrical energy into magnetic energy, and transmitting it to the multifunctional composite material in the reactor, thereby realizing the direct heating of the interior of the multifunctional composite material and realizing the conversion of magnetic energy into thermal energy.

[0046] Furthermore, the inlet end of the induction heating power supply 51 is connected to the industrial chiller 6.

[0047] Preferably, the material of the induction heating coil 52 is any one of pure copper, red copper, silver alloy, nickel alloy, high-temperature alloy steel nickel-aluminum alloy, nickel-silicon alloy, platinum-containing alloy, palladium-containing alloy, and Litz wire; more preferably, the number of turns of the induction heating coil 52 is 2 to 10, and the material is preferably red copper.

[0048] Furthermore, the induction heating power supply 52 has two control modes: constant current and constant power; wherein: When the constant current control mode is selected, the heating power and heating speed will change with the temperature of the workpiece. For ferromagnetic materials, the heating speed increases and the heating power decreases when the material is cold due to its high permeability and low equivalent impedance. When the material is hot above 600℃, the equivalent impedance increases due to the change in magnetism, the heating speed decreases and the heating power decreases. When the constant power control mode is selected, the power output of the equipment remains constant. Regardless of whether the workpiece is cold or hot, magnetic or non-magnetic, the equipment maintains a constant output power, which ensures that the heating power remains basically unchanged. This allows for a higher heating rate during the hot phase, which is beneficial for obtaining higher heating temperatures.

[0049] 1.2 Method for Variable Temperature Carbon Dioxide Capture and In-situ Conversion Driven by Electromagnetic Induction Heating Using the system described in 1.1 above, the method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating includes the following steps: S1. Induced activation of multifunctional composite materials: A reducing gas is introduced into the carbon capture-in-situ conversion integrated unit to reduce the catalytic components in the multifunctional composite materials into metal active sites; S2. Air / Flue Gas Pretreatment: Open the flow regulating valve V1. The air or industrial flue gas entering the system first enters the dust removal device 1 in the pretreatment unit to remove fine particulate dust from the air or industrial flue gas, so as to avoid clogging the subsequent reactor 3 or affecting the catalytic performance of the multifunctional composite material. If the temperature of the air or industrial flue gas is lower than the adsorption reaction temperature of the reactor 3, the first-level temperature control plate 21 in the pretreatment unit is turned on to match the temperature of the air or industrial flue gas with the adsorption reaction temperature. S3. Carbon Dioxide Capture: Open flow regulating valves V2, V7, and V9 to allow pretreated air or industrial flue gas to enter the first fixed-bed reactor 31. Start the electromagnetic induction heating device and adjust the power or current of the induction heating power supply to maintain a constant adsorption reaction temperature in the reactor. After adsorption treatment by the multifunctional composite material, low-temperature adsorption and capture of carbon dioxide is achieved. After adsorption saturation, switch the flow regulating valves and open V2, V6, and V8 to allow pretreated air or industrial flue gas to enter the second fixed-bed reactor 32. After adsorption treatment by the multifunctional composite material, low-temperature adsorption and capture of carbon dioxide is achieved. The decarbonized gas after adsorption treatment is discharged after waste heat is recovered through heat exchanger 7. S4. In-situ conversion of adsorbed carbon dioxide: Start the electromagnetic induction heating device 5, and adjust the power or current of the induction heating power supply 51 to raise the temperature of the first fixed bed reactor 31 and the second fixed bed reactor 32 after adsorption saturation to the conversion reaction temperature, and keep the temperature constant to match the temperature of the product. Then, by switching the flow control valves V5, V6, V7, V8 and V9, the reducing gas is introduced into the first fixed bed reactor 31 and the second fixed bed reactor 32. Under the synergistic effect of the catalysis of the multifunctional composite material and the alternating magnetic field, the captured carbon dioxide is converted in situ to generate product gas containing the target product. S5. Product gas separation and purification: The product gas enters the condenser 8 and the separation device 9 in the separation-purification unit in sequence to collect the target product.

[0050] This system achieves alternating operation of carbon dioxide adsorption and conversion processes in two reactors by controlling the flow regulating valves.

[0051] Furthermore, the reaction temperature of the integrated carbon capture-in-situ conversion unit is 25–800°C, the adsorption reaction temperature is 25–300°C, and the conversion reaction temperature is 25–800°C.

[0052] Furthermore, the current range of the adsorption reaction in step S3 is 0 to 100 A; the power range of the adsorption reaction is 10 W to 50 KW.

[0053] More preferably, the current range of the adsorption reaction in step S3 is 0 to 80 A, and the power range of the adsorption reaction is 10 W to 10 KW.

[0054] Furthermore, the current range of the conversion reaction in step S4 is 0 to 200A, and the power range of the conversion reaction is 10W to 100KW.

[0055] More preferably, the current range of the conversion reaction in step S4 is 0 to 100A, and the power range of the conversion reaction is 10W to 20KW.

[0056] Further, the reaction pressure of the integrated carbon capture-in-situ conversion unit is 0.01 to 5 MPa; preferably, the reaction pressure of the integrated carbon capture-conversion unit is 0.1 to 0.5 MPa.

[0057] Further, the carbon dioxide in the integrated carbon capture-in-situ conversion unit is carbon dioxide from air or industrial flue gas; preferably, the carbon dioxide content in the air or industrial flue gas is 0.01 to 90 vol; more preferably, the carbon dioxide content in the air or industrial flue gas is 0.04 to 30 vol; even more preferably, the carbon dioxide content in the air or industrial flue gas is 0.04 to 20 vol.

[0058] More preferably, the temperature of the air or industrial flue gas is 0–300°C; more preferably, the temperature of the air or industrial flue gas is 25–150°C.

[0059] Furthermore, the reducing gas is selected from any one or more of hydrogen, methane, ethane, and propane.

[0060] Further, the activation time of the multifunctional composite material is 1 min to 10 h; preferably, the activation time of the multifunctional composite material is 30 min to 3 h.

[0061] Example 2: The reactor is a circulating electromagnetic induction fluidized bed reactor. 2.1 Electromagnetic Induction Heating Driven Variable Temperature Carbon Dioxide Capture and In-situ Conversion System This embodiment uses the system described in Embodiment 1, with the difference being: as follows Figure 3As shown, the integrated carbon capture-in-situ conversion unit includes two reactors 3 and two cyclone separators 4, specifically including a first fluidized bed reactor 33 and a second fluidized bed reactor 34, which are respectively connected to the first cyclone separator 41 and the second cyclone separator 42. The integrated carbon capture-in-situ conversion unit completes the adsorption and capture and in-situ conversion of carbon dioxide under variable temperature conditions where the adsorption reaction temperature and the conversion reaction temperature are different. The inlet of the first fluidized bed reactor 33 is connected to the outlet of the primary temperature control plate 21, and the inlet of the second fluidized bed reactor 34 is connected to the outlet of the secondary temperature control plate 22. The outlet of the first fluidized bed reactor 33 is connected to a first cyclone separator 41 and is connected to the inlet of the heat exchanger 7. The outlet of the second fluidized bed reactor 34 is connected to a second cyclone separator 42 and is connected to the inlet of the separation-purification unit.

[0062] 2.2 Method for Variable Temperature Carbon Dioxide Capture and In-situ Conversion Driven by Electromagnetic Induction Heating Using the system described in 2.1 above, the method includes the following steps: S1. Induced activation of multifunctional composite materials: A reducing gas is introduced into the carbon capture-in-situ conversion integrated unit to reduce the catalytic components in the multifunctional composite materials into metal active sites; S2. Air / Flue Gas Pretreatment: Open the flow regulating valve V1. The air or industrial flue gas entering the system first enters the dust removal device 1 in the pretreatment unit to remove fine particulate dust from the air or industrial flue gas, so as to avoid clogging the subsequent reactor 3 or affecting the catalytic performance of the multifunctional composite material. If the temperature of the air or industrial flue gas is lower than the adsorption reaction temperature of the reactor 3, the first-level temperature control plate 21 in the pretreatment unit is turned on to match the temperature of the air or industrial flue gas with the adsorption reaction temperature. S3. Carbon dioxide capture: The pretreated air or industrial flue gas is introduced into the first fluidized bed reactor 33. The electromagnetic induction heating device is started. By adjusting the power or current of the induction heating power supply, the reactor temperature is kept constant at the adsorption reaction temperature. After adsorption treatment by the multifunctional composite material, the low-temperature adsorption and capture of carbon dioxide is achieved. The decarbonized gas after adsorption treatment is discharged after the waste heat is recovered by the heat exchanger 7. S4. In-situ conversion of adsorbed carbon dioxide: Start the electromagnetic induction heating device 5, and adjust the power or current of the induction heating power supply 51 to raise the temperature of the second fluidized bed reactor 34 to the conversion reaction temperature and keep the temperature constant, while matching the temperature of the product. When the first fluidized bed reactor 33 is saturated with adsorption, the multifunctional composite material will enter the second fluidized bed reactor 34 through the first cyclone separator 41. Open the flow control valves V2 and V3 to introduce reducing gas into the second fluidized bed reactor 34. Under the catalytic effect of the multifunctional composite material and the synergistic effect of the alternating magnetic field, the captured carbon dioxide is converted in situ to generate product gas containing the target product. S5. Product gas separation and purification: The multifunctional composite material that has completed the conversion will return to the first fluidized bed reactor 33 through the second cyclone separator 42, while the obtained product gas will enter the condenser 8 and the separation device 9 in the separation-purification unit to collect the target product.

[0063] Preparation examples: Conventional preparation methods for different multifunctional composite materials used in the examples and comparative examples. (1) Preparation method of NiFe / zeolite multifunctional composite material 5.07 g of nickel nitrate hexahydrate and 7.05 g of ferric nitrate nonahydrate were dissolved in 150 mL of deionized water. 8.0 g of zeolite support was added and stirred at room temperature for 2 h. After drying at 80 °C, the mixture was calcined in a muffle furnace at 550 °C for 3 h (calcination equipment heating rate was 5 °C / min) to obtain the NiFe / zeolite multifunctional composite material, which was then granulated to a mesh size of 40–60. The adsorption component accounted for 80%, while the magnetic and catalytic components were the same substance, accounting for 20%.

[0064] (2) Preparation method of Ni-CeO2 / Fe3O4 / activated carbon multifunctional composite material 6.0 g of activated carbon and 3.5 g of Fe3O4 were ultrasonically dispersed in 300 mL of deionized water. 0.63 g of nickel nitrate hexahydrate and 0.94 g of cerium nitrate hexahydrate were added and stirred for impregnation. NaOH was added dropwise to adjust the pH, causing CeO2 and NiO to co-precipitate on the carrier surface. After aging and washing, the mixture was dried at 80 °C and calcined at 500 °C for 4 h under a nitrogen atmosphere (heating rate of 5 °C / min) to obtain the Ni-CeO2 / Fe3O4 / activated carbon multifunctional composite material, which was then granulated to a mesh size of 40–60. The composition consisted of 60% adsorption components, 35% magnetic components, and 5% catalytic components.

[0065] (3) Preparation method of Ru-Al2O3 / Fe3O4 / K2CO3 multifunctional composite material 5.0 g Fe3O4 and 0.54 g Al2O3 were ultrasonically dispersed in 200 mL deionized water, and 0.65 g ruthenium chloride solution was added and stirred for impregnation. After drying at 80 °C, the mixture was calcined in air at 500 °C for 4 h (the heating rate of the calcination equipment was 5 °C / min). Subsequently, the product was immersed in a solution containing 4.0 g K2CO3 and stirred at room temperature until adsorption equilibrium was reached. It was dried again and calcined at 200 °C for 1 h to obtain the Ru-Al2O3 / Fe3O4 / K2CO3 multifunctional composite material, which was then granulated at 40–60 mesh. The composition of the composite material was 40% adsorbent, 50% magnetic, and 10% catalytic.

[0066] (4) Preparation method of Ni-Al2O3 / K2CO3 multifunctional composite material 9.05 g of nickel nitrate hexahydrate was dissolved in 250 mL of deionized water, and 3.17 g of Al₂O₃ support was added and stirred at room temperature for 2 h. After drying at 90 °C, it was calcined at 400 °C for 3 h to obtain Ni-Al₂O₃. This Ni-Al₂O₃ was then immersed in a solution containing 5.0 g of K₂CO₃ and stirred until adsorption reached equilibrium. After drying, it was calcined at 200 °C for 1 h to obtain the Ni-Al₂O₃ / K₂CO₃ multifunctional composite material, which was then granulated at a mesh size of 40–60. The adsorption component accounted for 50%, and the magnetic and catalytic components were the same substance, each accounting for 50%.

[0067] (5) Preparation method of CuGa / Fe3O4 / MgO multifunctional composite material 0.70 g of copper nitrate and 0.51 g of gallium nitrate were dissolved in 100 mL of deionized water. 2.5 g of Fe3O4 and 7.0 g of MgO support were added, and the mixture was stirred and impregnated at room temperature for 2 h. After drying at 80 °C, it was calcined at 400 °C for 3 h to obtain the CuGa / Fe3O4 / MgO multifunctional composite material, which was then granulated at a mesh size of 40–60. The composite material contained 70% adsorption components, 25% magnetic components, and 5% catalytic components.

[0068] (6) Preparation method of CuZn / Fe3O4 / LDH multifunctional composite material 4.5 g Fe3O4 was ultrasonically dispersed in 200 mL of deionized water. 1.45 g copper nitrate, 2.31 g zinc nitrate hexahydrate, and 4.5 g LDH mixed salt solution were added. NaOH was added dropwise until pH=10 for co-precipitation. After aging at room temperature, the mixture was transferred to a hydrothermal reactor and reacted at 120 °C for 12 h. The mixture was washed until neutral, dried at 110 °C, and then calcined at 300 °C for 2 h to obtain the CuZn / Fe3O4 / LDH multifunctional composite material, which was then granulated at 40–60 mesh. The composition consisted of 45% adsorption component, 45% magnetic component, and 10% catalytic component.

[0069] (7) Preparation method of CuMgFe / Na2CO3 multifunctional composite material 3.67 g of copper nitrate, 5.02 g of magnesium nitrate hexahydrate, and 7.90 g of ferric nitrate nonahydrate were dissolved in deionized water. 7.0 g of sodium carbonate was added and stirred at room temperature for impregnation. NaOH was added dropwise until pH=10, resulting in co-precipitation. After aging, the mixture was washed, dried at 80℃, and calcined at 400℃ for 3 hours to obtain the CuMgFe / Na2CO3 multifunctional composite material, which was then granulated to a mesh size of 40–60. The adsorption component accounted for 70%, while the magnetic and catalytic components were the same substance, accounting for 30%.

[0070] (8) Preparation method of CuFe / K2CO3-MgO multifunctional composite material 1.36 g of MgO was impregnated in a solution containing 4.64 g of K₂CO₃, dried, and calcined at 300 °C to obtain a K₂CO₃-MgO support. This support was then impregnated in a mixed solution of 6.28 g of copper nitrate and 13.53 g of ferric nitrate nonahydrate, stirred at room temperature for 3 h, dried at 80 °C, and calcined at 400 °C for 4 h to obtain a CuFe / K₂CO₃-MgO multifunctional composite material, which was granulated to a mesh size of 40–60. The adsorption component comprised 60%, while the magnetic and catalytic components were the same substance comprising 40%.

[0071] (9) Preparation method of Co-CeO2 / Li2ZrO3 multifunctional composite material Dissolve 6.30g of cobalt nitrate hexahydrate and 9.40g of cerium nitrate hexahydrate in deionized water, add 5.0g of Li2ZrO3 support, stir and impregnate at room temperature for 3 h, dry at 90℃ and calcine at 600 °C for 5 h to obtain Co-CeO2 / Li2ZrO3 multifunctional composite material, and granulate at 40-60 mesh. The adsorption component accounts for 50%, and the magnetic component and catalytic component are the same substance accounting for 50%. (10) Preparation method of Ni-Na2O / Fe3O4 multifunctional composite material: Disperse 5.0g of Fe3O4 in a mixed solution of 4.95g of nickel nitrate hexahydrate and 6.84g of sodium carbonate, stir and impregnate at room temperature for 2 h, dry at 80℃ and calcine at 400℃ for 3 h to obtain Ni-Na2O / Fe3O4 multifunctional composite material, and granulate at 40-60 mesh. The adsorption component accounts for 40%, the magnetic component accounts for 50%, and the catalytic component accounts for 10%.

[0072] (11) Preparation method of Ni-La-Al2O3 / Fe@C / K2CO3-MgO multifunctional composite material 17.86 g of ferric nitrate nonahydrate was dispersed in 14.4 g of glucose solution and hydrothermally carbonized at 180 °C to obtain Fe@C. Separately, 0.97 g of nickel nitrate hexahydrate and 1.08 g of lanthanum nitrate were impregnated in 0.34 g of Al₂O₃ and calcined at 400 °C to obtain Ni-La-Al₂O₃. Fe@C and Ni-La-Al₂O₃ were then dispersed in a solution containing 4.29 g of magnesium oxide and 1.71 g of potassium carbonate, stirred at room temperature, dried at 100 °C, and calcined at 300 °C for 2 h to obtain the Ni-La-Al₂O₃ / Fe@C / K₂CO₃-MgO multifunctional composite material, which was then granulated at 40–60 mesh. The composition of the composite material was 60% adsorption component, 30% magnetic component, and 10% catalytic component.

[0073] (12) Preparation method of NiPt / Fe3O4 / NaNO3-MgO multifunctional composite material 5.0 g of Fe3O4 was dispersed in a solution containing 1.29 g of magnesium oxide and 2.71 g of sodium nitrate, stirred and impregnated at room temperature, dried at 90 °C, and calcined at 350 °C to obtain a Fe3O4 / NaNO3-MgO support. This support was then immersed in a mixed solution of 1.15 g of nickel nitrate hexahydrate and 1.62 g of chloroplatinic acid, stirred at room temperature for 2 h, dried, and reduced at 450 °C for 2 h under a H2 / Ar atmosphere to obtain a NiPt / Fe3O4 / NaNO3-MgO multifunctional composite material, which was then granulated at a mesh size of 40–60. The composition of the composite material consisted of 40% adsorption components, 50% magnetic components, and 10% catalytic components.

[0074] (13) Preparation method of Co-V-ZrO2 / Li-Na2ZrO3 multifunctional composite material 6.24 g of cobalt nitrate hexahydrate and 7.74 g of ammonium vanadate were dissolved in deionized water, and 2.64 g of ZrO2 support was added and stirred at room temperature for 2 h. After drying at 90 °C, the mixture was calcined at 400 °C to obtain Co-V-ZrO2. Finally, Co-V-ZrO2 and Li-Na2ZrO3 were physically ground at a 1:1 ratio to obtain the Co-V-ZrO2 / Li-Na2ZrO3 multifunctional composite material, which was then granulated at a mesh size of 40–60. The adsorption component accounted for 50%, and the magnetic component and catalytic component were the same substance, with the catalytic component accounting for 50%.

[0075] (14) Preparation method of Co-ZSM-5 / NaNO3-MgO multifunctional composite material 4.95 g of cobalt nitrate hexahydrate was dissolved in 100 mL of deionized water, and 3 g of ZSM-5 molecular sieve was added and stirred at room temperature for 2 h. After drying at 100 °C, it was calcined at 500 °C for 3 h to obtain Co-ZSM-5. Next, a solution containing 1.70 g of magnesium oxide and 4.30 g of sodium nitrate was stirred at room temperature for 2 h, dried at 90 °C, and calcined at 350 °C to obtain NaNO3-MgO. Finally, Co-ZSM-5 and NaNO3-MgO were physically ground at a 1:1 ratio to obtain the Co-ZSM-5 / NaNO3-MgO multifunctional composite material, which was then granulated at a mesh size of 40-60. The adsorption component accounted for 60%, and the magnetic component and catalytic component were the same substance, accounting for 40%.

[0076] (15) Preparation method of Pt-Sn-Al2O3 / Co@C / KNO3-MgO multifunctional composite material Co@C was obtained by hydrothermal carbonization of 13.97g of cobalt nitrate hexahydrate with 14.4g of glucose solution at 180℃. Pt-Sn-Al2O3 was obtained by impregnating 0.25g of Al2O3 with 0.99g of chloroplatinic acid and 0.63g of tin chloride and calcining at 400℃. Co@C and Pt-Sn-Al2O3 were then dispersed in a solution containing 4.29g of magnesium oxide and 1.71g of potassium nitrate, stirred at room temperature, dried at 80℃, and calcined at 300℃ for 2 hours to obtain a multifunctional Pt-Sn-Al2O3 / Co@C / KNO3-MgO composite material, which was then granulated at 40-60 mesh. The composite material contained 60% adsorption components, 30% magnetic components, and 10% catalytic components.

[0077] (16) Preparation method of Pt-Zn / Fe3O4 / K2CO3-MgO multifunctional composite material 3.2 g of Fe3O4 was dispersed in a solution containing 1.47 g of magnesium oxide and 5.03 g of potassium carbonate and stirred at room temperature. After drying at 100 °C, it was calcined at 350 °C to obtain Fe3O4 / K2CO3-MgO. This Fe3O4 / K2CO3-MgO was then immersed in a mixed solution containing 0.47 g of chloroplatinic acid and 0.34 g of zinc nitrate hexahydrate and stirred at room temperature for 2 h. After drying, it was reduced at 500 °C for 2 h under a H2 / Ar atmosphere to obtain a Pt-Zn / Fe3O4 / K2CO3-MgO multifunctional composite material, which was then granulated at a mesh size of 40–60. The composite material contained 65% adsorption components, 32% magnetic components, and 3% catalytic components.

[0078] (17) Preparation method of Ga-Co-ZrO2 / Na2O-Al2O3 multifunctional composite material 1.62 g of gallium nitrate and 3.47 g of cobalt nitrate hexahydrate were dissolved in deionized water, and then 1.47 g of ZrO2 and 7.0 g of Na2O-Al2O3 mixed support were added and stirred at room temperature for 2 h. After drying at 80 °C, the mixture was calcined at 450 °C for 5 h to obtain the Ga-Co-ZrO2 / Na2O-Al2O3 multifunctional composite material, which was then granulated at a mesh size of 40–60. The adsorption component accounted for 70%, and the magnetic component and catalytic component were the same substance, accounting for 30%.

[0079] (18) Preparation method of Ga-V-ZrO2 / FeCo / Na2O-ZrO2 multifunctional composite material 12.32 g of ferric nitrate nonahydrate, 8.87 g of cobalt nitrate hexahydrate, 0.56 g of gallium nitrate, and 1.48 g of ammonium vanadate were dissolved in 300 mL of deionized water. 5.5 g of Na₂O-ZrO₂ support was added and stirred at room temperature for 2 h. After drying at 110 °C, the mixture was reduced at 500 °C for 5 h under an H₂ / Ar atmosphere to obtain the Ga-V-ZrO₂ / FeCo / Na₂O-ZrO₂ multifunctional composite material, which was then granulated to a mesh size of 40–60. The composition of the composite material consisted of 55% adsorption components, 35% magnetic components, and 10% catalytic components.

[0080] (19) Preparation method of Ca-SiO2 / Fe3O4 / K2CO3-MgO multifunctional composite material 3.5 g of Fe3O4 was ultrasonically dispersed in a silica sol containing 0.52 g of gallium nitrate. The mixture was stirred at room temperature to hydrolyze and condense, forming a gel. After drying at 95 °C, it was calcined at 400 °C for 3 h to obtain Ca-SiO2 / Fe3O4. This gel was then immersed in a mixed solution containing 3.40 g of potassium carbonate and 2.60 g of magnesium nitrate, stirred at room temperature for 2.5 h, dried, and calcined at 300 °C for 2 h to obtain the Ca-SiO2 / Fe3O4 / K2CO3-MgO multifunctional composite material, which was then granulated at a mesh size of 40–60. The composite material contained 60% adsorption components, 35% magnetic components, and 5% catalytic components.

[0081] (20) Preparation method of Fe-V-ZrO2 / Fe@C / KNO3-MgO multifunctional composite material Fe@C was obtained by hydrothermal carbonization of 17.86g of ferric nitrate nonahydrate and 14.4g of glucose solution at 180℃. Fe-V-ZrO2 was obtained by impregnating 0.54g of ZrO2 with 1.76g of ferric nitrate nonahydrate and 1.57g of ammonium vanadate, followed by calcination at 400℃. Fe@C and Fe-V-ZrO2 were then dispersed in a solution containing 4.29g of magnesium oxide and 1.71g of potassium nitrate, stirred at room temperature, dried at 80℃, and calcined at 300℃ for 3 hours. This yielded a multifunctional composite material of Fe-V-ZrO2 / Fe@C / KNO3-MgO, which was granulated to a mesh size of 40-60. The composition of the composite material consisted of 60% adsorption components, 30% magnetic components, and 10% catalytic components.

[0082] (21) Preparation method of NiFe / porous carbon multifunctional composite material 10.15 g of nickel nitrate hexahydrate and 14.11 g of ferric nitrate nonahydrate were dissolved in deionized water, and 6.0 g of porous carbon was added and stirred at room temperature for 2 h. After drying at 95 °C, the mixture was calcined at 400 °C for 3 h under a N2 atmosphere to obtain a Ni-Fe / porous carbon multifunctional composite material, which was then granulated at a mesh size of 40–60. The adsorption component accounted for 60%, and the magnetic component and catalytic component were the same substance, accounting for 40%.

[0083] Examples 3 to 22 This embodiment employs the electromagnetic induction heating-driven variable-temperature carbon dioxide capture and in-situ conversion system and method from Example 1, such as... Figure 2 As shown, the method is as follows: Using methane, carbon monoxide, syngas, ethylene, and propylene as different target product gases, a reducing gas was used to induce activation of the multifunctional composite material. The reaction pressure was approximately 0.1 MPa. Different multifunctional composite materials were used, and the induction heating power supply adopted a constant current or constant power control mode. At the same time, the flue gas volume hourly space velocity, hydrogen volume hourly space velocity, and the adsorption and conversion reaction temperatures were controlled to obtain the target product. Different embodiments were set up accordingly. Specific parameters are shown in Table 1.

[0084] Example 23 This embodiment employs the electromagnetic induction heating-driven variable-temperature carbon dioxide capture and in-situ conversion system and method from Embodiment 2, such as... Figure 3 As shown, the method is as follows: After induced activation of the multifunctional composite material FeNi / porous carbon filled in the first fluidized bed reactor 33 and the second fluidized bed reactor 34 with hydrogen for 1 h, the CO2 adsorption capacity of the multifunctional composite material reached 2-4 mmol / g; with methane as the target product gas, the volume hourly space velocity of the flue gas introduced into the system was maintained at 10000 h⁻¹. -1 The volume hourly space velocity of hydrogen is 10,000 h⁻¹. -1The adsorption current and conversion current were controlled to be 5.4A and 14.3A, respectively, to obtain the target product.

[0085] Comparative Example 1 This comparative example uses the electromagnetic induction heating-driven variable temperature carbon dioxide capture and in-situ conversion system and method of Example 2, the difference being that electromagnetic induction heating is replaced by a conventional heating method (resistance heating).

[0086] Comparative Example 2 This comparative example uses the electromagnetic induction heating-driven variable temperature carbon dioxide capture and in-situ conversion system and method of Example 4, the difference being that an equal amount of magnetic material: Fe3O4 is used instead of the multifunctional composite material.

[0087] Comparative Example 3 This comparative example uses the electromagnetic induction heating driven variable temperature carbon dioxide capture and in-situ conversion system and method of Example 9, the difference being that: a current of 23.5A is used for carbon dioxide capture and in-situ conversion instead of a current of 8.1A for capture and 23.5A for conversion.

[0088] Performance testing The CO2 capture rate, adsorbed CO2 conversion rate, and product selectivity of Examples 3 to 23 and Comparative Examples 1 to 3 were tested, and the specific data are listed in Table 1.

[0089] Table 1 The data above shows that using electromagnetic induction heating for variable-temperature carbon dioxide capture and in-situ conversion can significantly improve the capture and conversion efficiency of carbon dioxide, effectively reduce energy consumption and increase the reaction heating rate during the reaction process, which is beneficial for carbon dioxide capture and in-situ conversion.

[0090] Comparative Example 1, which replaced electromagnetic induction heating with traditional resistance heating, showed relatively low carbon dioxide conversion rate and product selectivity. This is likely because the induced current generated by electromagnetic induction heating has a skin effect, causing electrons to accumulate on the catalyst surface, thereby promoting carbon dioxide adsorption and activation. Comparative Example 2, which replaced the multifunctional composite material with an equal amount of magnetic material Fe3O4, essentially did not perform carbon dioxide capture or in-situ conversion. This is because Fe3O4 is not a carbon dioxide adsorbent, resulting in an extremely low carbon dioxide capture rate and virtually no carbon dioxide conversion. Comparative Example 3, which used a 23.5A current for carbon dioxide capture and in-situ conversion instead of an 8.1A capture current for conversion, also showed unsatisfactory results. This is because carbon dioxide adsorption is an exothermic process, and sustained high temperatures are detrimental to capture, leading to a significant decrease in the carbon dioxide capture rate and consequently affecting the conversion efficiency.

[0091] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present application in any way. Although the present application discloses the preferred embodiment as described above, it is not intended to limit the present application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A system for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating, characterized in that, The system includes a pretreatment unit, an integrated carbon capture-in-situ conversion unit, a waste heat recovery unit, and a separation-purification unit. The integrated carbon capture-in-situ conversion unit is equipped with an electromagnetic induction heating device. The integrated carbon capture-in-situ conversion unit includes at least two reactors, which are multi-stage parallel electromagnetic induction fixed-bed reactors or circulating electromagnetic induction fluidized-bed reactors. The interior of each reactor is filled with a multifunctional composite material, which includes magnetic components, adsorption components, and conversion components.

2. The system for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating according to claim 1, characterized in that, The magnetic component is selected from any one or more combinations of Fe, Co, Ni, Gd, Dy, Ho, Er, Tm, FeCo, FeNi, NiCo, NiFe2O4, CoFe2O4, MnFe2O4, and Fe3O4; the adsorption component is selected from any one or more combinations of carbon-based materials, zeolites, molecular sieves, metal-organic framework materials, solid amines, alkali metal oxides, alkali metal carbonates, magnesium oxide, and hydrotalcite-like derivatized adsorbents; the conversion component is selected from any one or more combinations of Ni, Ru, Co, Fe, La, Ce, Mn, Cu, Rh, Pt, Pd, Ir, Sr, Cr, Ca, Zn, Sn, V, and Ge. The magnetic component has a mass percentage of 0.1% to 60% in the multifunctional composite material; the adsorption component has a mass percentage of 0.1% to 80% in the multifunctional composite material; and the catalytic component has a mass percentage of 0.1% to 20% in the multifunctional composite material.

3. The system for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating according to claim 1, characterized in that, The magnetic component has a mass percentage of 0.1% to 60% in the multifunctional composite material; the adsorption component has a mass percentage of 0.1% to 80% in the multifunctional composite material; and the catalytic component has a mass percentage of 0.1% to 20% in the multifunctional composite material.

4. The system for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating according to claim 1, characterized in that, The pretreatment unit includes an electrostatic dust removal device, a primary temperature control panel, and a secondary temperature control panel; The integrated carbon capture-in-situ conversion unit completes the adsorption and in-situ conversion of carbon dioxide under variable temperature conditions where the adsorption reaction temperature and the conversion reaction temperature are different. When the reactor is a multi-stage parallel electromagnetic induction fixed-bed reactor, the integrated carbon capture-in-situ conversion unit includes two reactors, specifically a first fixed-bed reactor and a second fixed-bed reactor. When the reactor is a circulating electromagnetic induction fluidized-bed reactor, the integrated carbon capture-in-situ conversion unit includes two reactors and two cyclone separators, specifically a first fluidized-bed reactor and a second fluidized-bed reactor, which are respectively connected to the first cyclone separator and the second cyclone separator. The waste heat recovery unit includes an industrial chiller and a heat exchanger; The separation and purification unit includes a condensation device and a separation device, used to condense and separate the product gas to obtain the target product; The inlets of the two reactors are connected to the outlets of the primary temperature control plate and the secondary temperature control plate, respectively; the outlets of the two reactors are connected to the inlet of the heat exchanger and the inlet of the separation-purification unit, respectively.

5. The system for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating according to claim 1, characterized in that, The electromagnetic induction heating device includes an induction heating power supply and an induction heating coil; wherein... The induction heating power supply is selected from any one of low-frequency induction heating power supply, medium-frequency induction heating power supply, high-frequency induction heating power supply and ultra-high-frequency induction heating power supply. The induction coil is a multi-turn spiral coil, which is wrapped around the outside of the reactor or located in the hollow cavity formed by the inner and outer tubes, forming an alternating magnetic field inside the electromagnetic induction heating device.

6. A method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating, employing the system described in any one of claims 1-5, characterized in that, The method includes the following steps: S1. Induced activation of multifunctional composite materials: A reducing gas is introduced into the carbon capture-in-situ conversion integrated unit to reduce the catalytic components in the multifunctional composite materials into metal active sites; S2, Air / Flue Gas Pretreatment: The air or industrial flue gas input into the system is passed into the pretreatment unit for dust removal and temperature control, so that the temperature of the air or industrial flue gas matches the adsorption reaction temperature. S3. Carbon dioxide capture: Pretreated air or industrial flue gas is introduced into the reactor, and the electromagnetic induction heating device is started. By adjusting the power or current of the induction heating power supply, the reactor temperature is maintained at a constant adsorption reaction temperature. After adsorption treatment by multifunctional composite materials, low-temperature adsorption and capture of carbon dioxide is achieved. The decarbonized gas after adsorption treatment is discharged after waste heat is recovered by a heat exchanger. S4. In-situ conversion of adsorbed carbon dioxide: Start the electromagnetic induction heating device, and adjust the power or current of the induction heating power supply to raise the temperature of the reactor after adsorption saturation to the conversion reaction temperature and keep the temperature constant. Then, introduce reducing gas into the reactor. Under the synergistic effect of the catalysis of the multifunctional composite material and the alternating magnetic field, the captured carbon dioxide is converted in-situ to generate product gas containing the target product. S5. Product gas separation and purification: The product gas is introduced into the separation and purification unit, and the target product is collected after condensation and separation.

7. The method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating according to claim 6, characterized in that, The reaction temperature of the integrated carbon capture-in-situ conversion unit is 25–800℃, the adsorption reaction temperature is 25–300℃, and the conversion reaction temperature is 25–800℃; the reaction pressure of the integrated carbon capture-in-situ conversion unit is 0.01–5 MPa.

8. The method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating according to claim 6, characterized in that, The current range of the adsorption reaction in step S3 is 0 to 100 A; the power range of the adsorption reaction is 10 W to 50 KW.

9. The method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating according to claim 6, characterized in that, The current range of the conversion reaction in step S4 is 0 to 200A, and the power range of the conversion reaction is 10W to 100KW.

10. The method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating according to claim 6, characterized in that, The reducing gas is selected from any one or more of hydrogen, methane, ethane, and propane.

11. The method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating according to claim 6, characterized in that, When the reactor is a multi-stage parallel electromagnetic induction fixed-bed reactor, after one fixed-bed reactor becomes saturated with adsorption, pretreated air or industrial flue gas is introduced into another fixed-bed reactor to continue adsorption and capture. At the same time, reducing gas is introduced into the saturated fixed-bed reactor. Under the synergistic effect of electromagnetic induction heating, catalysis of multifunctional composite materials, and alternating magnetic field, in-situ carbon dioxide conversion is completed. The two fixed-bed reactors operate alternately periodically to achieve continuous carbon dioxide capture-in-situ conversion.

12. The method for variable-temperature carbon dioxide capture and in-situ conversion driven by electromagnetic induction heating according to claim 6, characterized in that, When the reactor is a circulating electromagnetic induction fluidized bed reactor, after the multifunctional composite material in the first fluidized bed reactor is saturated with adsorption, it is transferred to the second fluidized bed reactor via the first cyclone separator. In the second fluidized bed reactor, carbon dioxide is converted in situ under the synergistic effect of electromagnetic induction heating, reducing gas, and alternating magnetic field to generate product gas containing the target product. After conversion, the multifunctional composite material is returned to the first fluidized bed reactor via the second cyclone separator to participate in carbon dioxide adsorption and capture again. The cyclone separator realizes the cyclic transfer of the multifunctional composite material between the two fluidized bed reactors, forming a continuous cycle process of adsorption-conversion-re-adsorption.

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