System for coupling carbon dioxide capture and in-situ methanation

Abstract

The utility model provides a system for coupling carbon dioxide capture and in-situ methanation, which comprises a gas conveying and switching unit, an adsorption and conversion unit, a product collection unit and a pressure control unit, and the gas conveying and switching unit comprises a nitrogen pipeline, a flue gas pipeline and a hydrogen pipeline; the adsorption and conversion unit is filled with a composite material with double functions of adsorption and catalysis; the product collection unit is connected to the downstream of the adsorption and conversion unit; and the pressure control unit is connected between the adsorption and conversion unit and the product collection unit. According to the utility model, not only is carbon emission reduction of the petrochemical industry realized, but also high value-added utilization of carbon dioxide is realized, and liquid fuel is provided for the petrochemical industry; on the other hand, adsorption and conversion are completed in the same reactor, so that high cost and high energy consumption in the process of compressing, liquefying and transporting carbon dioxide connected with carbon capture and utilization are greatly reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to carbon dioxide capture and methanol preparation technical field especially relates to a system of coupling carbon dioxide capture and in situ methanation. BACKGROUND

[0002] The flue gas temperature discharged in the production process of petrochemical industry is usually between 200 DEG C to 400 DEG C, and the carbon dioxide concentration is between 10-20%, in order to balance the contradiction between the development of petrochemical industry and the double carbon target, carbon dioxide capture, utilization and storage technology is becoming a new way to alleviate carbon dioxide emission.

[0003] 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 technology.

[0004] Among the carbon one products converted by carbon dioxide, methanol is called "liquid sunshine" due to its economic benefit and practical value. Methanol is widely used in chemical industry and fuel industry, and can also be used as energy-intensive synthetic fuel directly in shipping industry and industries difficult to decarbonize (such as heavy-duty vehicles, aviation). However, the process of synthesizing methanol from carbon dioxide and hydrogen under the action of catalyst still faces the technical bottleneck of low conversion rate, and there is still a certain distance from industrialization. At present, the research on the system and method of capturing carbon dioxide from petrochemical industry flue gas and converting it into methanol in situ is still in blank. SUMMARY

[0005] The utility model aims at solving one of the technical problems in the related art at least to some extent. Therefore, the utility model embodiment provides a system of coupling carbon dioxide capture and in situ methanation, which realizes carbon emission reduction of petrochemical industry and high value-added utilization of carbon dioxide, and adsorption and conversion are completed in the same reactor, thereby reducing cost and energy consumption.

[0006] The utility model discloses a kind of coupling carbon dioxide capture and in situ methanation system, comprising: gas delivery and switching unit, adsorption and conversion unit, product collection unit and pressure control unit, the gas delivery and switching unit includes nitrogen pipeline, flue gas pipeline and hydrogen pipeline, the nitrogen pipeline, the flue gas pipeline and the hydrogen pipeline are connected in parallel in main pipeline;The adsorption and conversion unit is connected to the main pipeline, the adsorption and conversion unit is filled with composite material with adsorption and catalysis dual function, to complete carbon dioxide adsorption and in situ methanation, temperature adjusting mechanism is equipped in the adsorption and conversion unit;The product collection unit is connected to the downstream of the adsorption and conversion unit, to collect the methanol generated;The pressure control unit is connected between the adsorption and conversion unit and the product collection unit.

[0007] In some embodiments, the pressure control unit includes a back pressure valve and a solenoid valve connected to the main pipeline, and the back pressure valve and the solenoid valve each have a passage for exhaust.

[0008] In some embodiments, the product collection unit includes a serpentine condenser and a collection tank, and the serpentine condenser is arranged at the feed inlet of the collection tank.

[0009] In some embodiments, the nitrogen pipeline is connected with a first pressure reducing valve and a first flow valve, the flue gas pipeline is connected with a second pressure reducing valve and a second flow valve, and the hydrogen pipeline is connected with a third pressure reducing valve and a third flow valve.

[0010] In some embodiments, the gas delivery and switching unit further includes a gas mixing tank, and the gas mixing tank is connected to the main pipeline.

[0011] In some embodiments, the composite material is a mixture of NaNO3 modified MgO and zinc oxide-zirconium oxide bimetallic oxide.

[0012] In some embodiments, the particle size of the NaNO3 modified MgO is 0.2-0.3 μm, and the particle size of the zinc oxide-zirconium oxide bimetallic oxide is 0.1-0.2 μm. BRIEF DESCRIPTION OF DRAWINGS

[0013] The above and / or additional aspects and advantages of the utility model will become apparent and more readily appreciated from the following description of the embodiments, with reference to the following drawings, in which:

[0014] Wherein:

[0015] Figure 1 It is the structure schematic drawing of the coupling carbon dioxide capture and in situ methanation system in the utility model embodiment;

[0016] 1. Gas delivery and switching unit; 11. First pressure reducing valve; 12. First flow valve; 13. Second pressure reducing valve; 14. Second flow valve; 15. Third pressure reducing valve; 16. Third flow valve; 17. Mixing tank; 2. Adsorption and conversion unit; 21. Composite material; 3. Pressure control unit; 31. Back pressure valve; 32. Solenoid valve; 4. Product collection unit; 41. Serpentine condenser; 42. Collection tank. Detailed Implementation

[0017] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0018] The following description, with reference to the accompanying drawings, describes a system for coupled carbon dioxide capture and in-situ methanolization according to an embodiment of the present invention.

[0019] like Figure 1 As shown in the figure, this utility model embodiment proposes a system coupling carbon dioxide capture and in-situ methanolization, including: a gas delivery and switching unit 1, an adsorption and conversion unit 2, a product collection unit 4, and a pressure control unit 3. The gas delivery and switching unit 1 includes a nitrogen pipeline, a flue gas pipeline, and a hydrogen pipeline, which are connected in parallel to the main pipeline. The adsorption and conversion unit 2 is connected to the main pipeline and is filled with a composite material 21 with dual functions of adsorption and catalysis to complete carbon dioxide adsorption and in-situ methanolization. The adsorption and conversion unit 2 is equipped with a temperature regulation mechanism. The product collection unit 4 is connected downstream of the adsorption and conversion unit 2 to collect the generated methanol. The pressure control unit 3 is connected between the adsorption and conversion unit 2 and the product collection unit 4.

[0020] This utility model embodiment, by setting up a gas delivery and switching unit 1, an adsorption and conversion unit 2, a product collection unit 4, and a pressure control unit 3, not only achieves carbon emission reduction in the petrochemical industry, but also realizes high-value utilization of carbon dioxide, providing liquid fuel for the petrochemical industry; on the other hand, adsorption and conversion are completed in the same reactor, avoiding the complex system of two reactors, and significantly reducing the high cost and high energy consumption of the carbon dioxide compression, liquefaction, and transportation processes that connect carbon capture and utilization.

[0021] By setting up a pressure control unit 3, the gas in the adsorption and conversion unit 2 can be discharged under normal pressure conditions, and the pressure in the adsorption and conversion unit 2 can be increased and maintained.

[0022] It should be noted that the adsorption and conversion unit 2 is specifically an adsorption and conversion device. Any device that can perform this function is acceptable and is not limited here.

[0023] In some embodiments, the pressure control unit 3 comprises a back pressure valve 31 and a solenoid valve 32 connected to the main pipeline, the back pressure valve 31 and the solenoid valve 32 respectively having a passage for exhaust.

[0024] In some embodiments, the gas delivery and switching unit 1 further comprises a gas mixing tank 17 connected to the main pipeline.

[0025] In some embodiments, the product collection unit 4 comprises a serpentine condenser 41 arranged at the inlet of a collection tank 42. By arranging the serpentine condenser 41, the collected gaseous methanol can be converted into liquid methanol for collection.

[0026] In some embodiments, a first pressure reducing valve 11 and a first flow valve 12 are connected to the nitrogen pipeline, a second pressure reducing valve 13 and a second flow valve 14 are connected to the flue gas pipeline, and a third pressure reducing valve 15 and a third flow valve 16 are connected to the hydrogen pipeline.

[0027] The embodiment of the utility model further proposes a method for coupling carbon dioxide capture and in-situ methanation, which utilizes the above system and comprises the following steps:

[0028] S1, nitrogen is introduced into the adsorption and conversion unit 2, the adsorption and conversion unit 2 is heated to 300-350 DEG C and kept for a period of time to pretreat the composite material 21, and the pretreated gas is discharged through the passage of the solenoid valve 32;

[0029] S2, flue gas is introduced into the adsorption and conversion unit 2, and the composite material 21 in the adsorption and conversion unit 2 adsorbs carbon dioxide in the flue gas, and the low-carbon flue gas after adsorption is discharged through the passage of the solenoid valve 32;

[0030] S3, nitrogen is introduced into the adsorption and conversion unit 2 for purging, and the purged gas is discharged through the passage of the solenoid valve 32;

[0031] S4, hydrogen is introduced into the adsorption and conversion unit 2 for purging, and the purged gas is discharged through the passage of the solenoid valve 32;

[0032] S5, the passage of the solenoid valve 32 is closed, the back pressure valve 31 and the pressure of hydrogen introduction are adjusted, hydrogen is introduced into the adsorption and conversion unit 2, the adsorption and conversion unit 2 is heated to 300-350 DEG C, and the methanol generated by the reaction of hydrogen and carbon dioxide is collected into the product collection unit 4.

[0033] The method of the embodiment of the utility model, in view of the feature of the medium temperature flue gas generated by petrochemical industry cracking furnace and reactor, directly transport to adsorb and conversion unit 2 and carry out adsorption, after a period of adsorption, switch the flue gas to nitrogen and hydrogen purging in order, after purging, raise the system pressure, after boosting, raise the temperature of adsorb and conversion unit 2, convert the adsorbed carbon dioxide into methanol, so circulate back and forth.

[0034] The system and method for coupling carbon capture and in-situ methanation of flue gas of petrochemical industry cracking furnace and reactor provided by the utility model, on the one hand, the adsorb and conversion unit 2 is filled with adsorption / catalysis dual-functional metal composite material, has high carbon dioxide adsorption capacity and high catalytic activity, realizes carbon emission reduction of petrochemical industry and high value-added utilization of carbon dioxide; on the other hand, adsorption and conversion are completed in the same reactor, avoids the complex system of two reactors, and greatly reduces the high cost and high energy consumption of the carbon dioxide compression, liquefaction and transportation process connecting carbon capture and utilization.

[0035] It should be noted that step S1 is a process of pretreating the composite material 21, and the effect is to remove the water and carbon dioxide naturally adsorbed in the adsorption active component in the composite material 21 during synthesis and storage, so as to improve the adsorption performance of the adsorption active component.

[0036] Further, the method for coupling carbon dioxide capture and in-situ methanation includes the following steps:

[0037] (1) composite material pretreatment: nitrogen is adjusted in pressure by the first pressure reducing valve 11, the flow rate is adjusted to 40ml / min by the first flow valve 12, and is input into the adsorb and conversion unit 2, the temperature of the adsorb and conversion unit 2 is adjusted to 300-350 DEG C, and is kept for 1 hour, and the gas after pretreatment is discharged through the passage of the electromagnetic valve 32 of the pressure control unit 3.

[0038] (2) flue gas carbon dioxide adsorption: the carbon dioxide concentration in the flue gas is fixed at 15%, the flue gas is adjusted in pressure by the second pressure reducing valve 13, the flow rate is adjusted to 40ml / min by the second flow valve 14, and is input into the adsorb and conversion unit 2, the temperature of the adsorb and conversion unit 2 is adjusted to 250-300 DEG C, after 1 hour of adsorption by the composite material 21, the carbon dioxide in the flue gas is captured, and the low carbon flue gas after adsorption is discharged through the passage of the electromagnetic valve 32;

[0039] (3) nitrogen purging: nitrogen is adjusted in pressure by the first pressure reducing valve 11, the flow rate is adjusted to 40ml / min by the first flow valve 12, and is input into the adsorb and conversion unit 2, the temperature is kept unchanged, i.e. 250-300 DEG C, and the gas after purging is discharged through the passage of the electromagnetic valve 32;

[0040] (4) Hydrogen purge: hydrogen gas was introduced into the adsorption and conversion unit 2 through the third pressure-reducing valve 15 to adjust the pressure and the third flow valve 16 to adjust the flow rate to 100 ml / min, the temperature was kept constant, i.e. 250-300°C, and the purged gas was discharged through the passage of the solenoid valve 32;

[0041] (5) System pressure rise: close the passage of the solenoid valve 32, adjust the pressure of the back pressure valve 31 to 3 MPa, hydrogen gas is introduced into the adsorption and conversion unit 2 through the third pressure-reducing valve 15 to adjust the pressure and the third flow valve 16 to adjust the flow rate to 100 ml / min, the temperature of the adsorption and conversion unit 2 is kept constant, i.e. 250-300°C, the duration is 50 min, and the gas required for pressure rise is discharged through the passage of the back pressure valve 31;

[0042] (6) In-situ conversion of carbon dioxide to methanol: the temperature of the adsorption and conversion unit 2 is raised and maintained at 300-350°C at a rate of 2°C / min, the only product of in-situ conversion in this process is methanol, the total amount of methanol is 80% of the total amount of adsorbed carbon dioxide, and the methanol produced by in-situ conversion is stored in the coiled condenser 41 or directly introduced into a gas chromatograph or other equipment for characterization and analysis.

[0043] Such alternation is repeated by the above steps to switch between adsorption and conversion, realizing continuous coupling of carbon dioxide capture and conversion to methanol.

[0044] In some embodiments, the composite material 21 is a mixture of NaNO3 modified MgO and zinc oxide-zirconium oxide bimetallic oxide, and the mass ratio of NaNO3 modified MgO to zinc oxide-zirconium oxide bimetallic oxide is 1:4.

[0045] It should be noted that the composite material 21 includes an adsorption active component and a catalytic active component, the adsorption active component is NaNO3 modified MgO, and the catalytic active component is zinc oxide-zirconium oxide bimetallic oxide, both of which are combined by physical mixing, perfectly match the adsorption and catalysis dual-function working conditions, and promote the working performance of each other: NaNO3 modified MgO has excellent adsorption capacity for the flue gas conditions of the petrochemical industry, and the regeneration temperature after adsorbing carbon dioxide matches the conversion temperature of zinc oxide-zirconium oxide bimetallic oxide, and the zinc oxide-zirconium oxide bimetallic oxide effectively divides the NaNO3 modified MgO particles, preventing the agglomeration of carbon dioxide adsorption products; in addition, under the hydrogen regeneration condition, a hydrogen-rich atmosphere is created after carbon dioxide is adsorbed and fixed by MgO, greatly improving the efficiency of carbon dioxide conversion to methanol.

[0046] Through the carbon dioxide adsorption and desorption test results, the adsorption amount of carbon dioxide of the composite material 21 is greater than 1 mol / kg within one hour, and the saturated adsorption can be up to 11.4 mol / kg; the carbon dioxide conversion rate is greater than 80%, which is much higher than the current conversion rate of about 25%; and the methanol selectivity is close to 100%.

[0047] Further, the MgO is synthesized by a hydrothermal method, the NaNO3 modification is realized by an impregnation method, and the zinc oxide-zirconium oxide bimetallic oxide is synthesized by a coprecipitation method.

[0048] In some embodiments, the particle size of the NaNO3 modified MgO is 0.2-0.3 μm, and the particle size of the zinc oxide-zirconium oxide bimetallic oxide is 0.1-0.2 μm.

[0049] In some embodiments, in the NaNO3 modified MgO, the molecular ratio of Na to Mg is 1:9.

[0050] In some embodiments, in the zinc oxide-zirconium oxide bimetallic oxide, the mole percentage of Zn / Zn+Zr elements is 13%.

[0051] In some embodiments, the preparation method of the NaNO3 modified MgO comprises the following steps:

[0052] P1, dissolving magnesium acetate tetrahydrate and urea in deionized water to obtain a first mixed solution, adjusting the pH value of the first mixed solution to 9.0, and then transferring to a Teflon high-pressure reaction kettle;

[0053] P2, placing the Teflon high-pressure reaction kettle in a muffle furnace for heating, after the reaction of magnesium acetate tetrahydrate and urea is completed, naturally cooling to room temperature, opening the Teflon high-pressure reaction kettle, filtering and collecting the white precipitate, and washing and drying the white precipitate to obtain a white powder;

[0054] P3, calcining the white powder in air to obtain MgO;

[0055] P4, dissolving MgO and NaNO3 in ethanol to obtain a mixed solution after stirring, and drying the mixed solution to obtain a dry white powder;

[0056] P5, calcining the dry white powder in air to obtain NaNO3 modified MgO.

[0057] Further, the preparation method of the NaNO3 modified MgO specifically comprises the following steps:

[0058] (1) dissolving 0.08 mol of magnesium acetate tetrahydrate and 0.24 mol of urea in 50 ml of deionized water to obtain a first mixed solution;

[0059] (2) The initial pH value of the first mixed solution in step (1) is controlled at 8.2, and the pH value is adjusted to 9.0 by adding 25-28% concentrated ammonia water;

[0060] (3) The first mixed solution in step (2) is transferred to a 100ml Teflon high-pressure reaction kettle;

[0061] (4) The Teflon high-pressure reaction kettle in step (3) is placed in a muffle furnace to heat the reaction at a temperature of 180°C for 5 hours, and after the reaction is completed, it is naturally cooled to room temperature;

[0062] (5) The Teflon high-pressure reaction kettle in step (4) is opened, the white precipitate is collected and washed with deionized water and anhydrous ethanol;

[0063] (6) The white precipitate of step (5) is washed and dried at 60°C for 4 hours to obtain a white powder;

[0064] (7) The white powder after drying in step (6) is calcined in air at a temperature of 500°C for 5 hours to obtain MgO;

[0065] (8) Take 1.8mol MgO and 0.2mol NaNO3, dissolve them in 100ml ethanol to obtain a mixed solution;

[0066] (9) The mixed solution in step (8) is stirred for 8 hours;

[0067] (10) The mixed solution in step (9) is dried at 60°C for 4 hours to obtain a dry white powder;

[0068] (11) The dry white powder in step (10) is calcined in air at a temperature of 350°C for 0.5 hours to obtain NaNO3 modified MgO.

[0069] In some embodiments, the method for preparing zinc oxide zirconium oxide bimetallic oxide includes the following steps:

[0070] Q1, zinc nitrate hexahydrate and zirconium nitrate pentahydrate are dissolved in deionized water to obtain a second mixed solution,

[0071] Q2, under stirring, ammonium carbonate solution is added to the second mixed solution to form a suspension, heated and stirred, fully reacted, cooled to room temperature, and the precipitate is collected after filtration, washed and dried to obtain a white powder;

[0072] Q3, the white powder is calcined and then reduced in a pure hydrogen atmosphere to obtain zinc oxide zirconium oxide bimetallic oxide.

[0073] Further, the method for preparing zinc oxide zirconium oxide bimetallic oxide includes the following steps:

[0074] (1) Dissolve 0.6 g of zinc nitrate hexahydrate and 5.8 g of zirconium nitrate pentahydrate in 100 ml of deionized water to obtain a second mixed solution;

[0075] (2) Under strong stirring, add a 100 ml aqueous solution containing 3.06 g of ammonium carbonate to the second mixed solution in step (1) at a flow rate of 3 ml / min to form a suspension;

[0076] (3) Continue stirring the suspension in step (2) at 70°C for 2 hours to ensure full reaction;

[0077] (4) Cool the stirred suspension in step (3) to room temperature;

[0078] (5) Collect the precipitate of step (4) by filtration and wash three times with deionized water;

[0079] (6) Filter the precipitate obtained in step (5) and dry at 110°C for 4 hours to obtain a white powder;

[0080] (7) Calcine the white powder obtained in step (6) in static air at a temperature of 500°C for 3 hours;

[0081] (8) Reduce the white powder obtained in step (7) under a pure hydrogen atmosphere at a temperature of 320°C for 1 hour to obtain a zinc oxide and zirconium oxide bimetallic oxide.

[0082] In some embodiments, in step S5, the pressure of the back pressure valve 31 is adjusted to 3 MPa, the pressure of the hydrogen gas inlet is adjusted by the third pressure reducing valve 15 of the hydrogen gas pipeline, the flow rate of the hydrogen gas is adjusted to 100 ml / min by the third flow valve 16, and the gas required for pressure increase is discharged through the passage of the back pressure valve 31.

[0083] In the description of the utility model, it is understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model.

[0084] In addition, the terms "first", "second", "third", etc. are used herein only to describe different instances, and are not used to indicate or imply relative importance or a number of indicated technical features. Thus, features defined with "first", "second", etc. can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0085] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or in communication with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication or interaction relationship of two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0086] In the present application, unless otherwise specifically defined and limited, the first feature is "on" or "under" the second feature. The first and second features can be in direct contact, or the first and second features can be in indirect contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0087] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the description, the illustrative representation of the above terms is not necessarily directed to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or features of different embodiments or examples described in the present application without contradiction.

[0088] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. Those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A system coupling carbon dioxide capture and in-situ methanolization, characterized in that, include: A gas delivery and switching unit, comprising a nitrogen pipeline, a flue gas pipeline and a hydrogen pipeline, wherein the nitrogen pipeline, the flue gas pipeline and the hydrogen pipeline are connected in parallel to the main pipeline; An adsorption and conversion unit is connected to the main pipeline. The adsorption and conversion unit is filled with a composite material with both adsorption and catalytic functions to complete carbon dioxide adsorption and in-situ methanolization. The adsorption and conversion unit is equipped with a temperature regulation mechanism. A product collection unit is connected downstream of the adsorption and conversion unit to collect the generated methanol; A pressure control unit is connected between the adsorption and conversion unit and the product collection unit.

2. The system for coupled carbon dioxide capture and in-situ methanolization according to claim 1, characterized in that, The pressure control unit includes a back pressure valve and a solenoid valve connected to the main pipeline, and the back pressure valve and the solenoid valve each have a passage for venting.

3. The system for coupled carbon dioxide capture and in-situ methanolization according to claim 1, characterized in that, The product collection unit includes a serpentine condenser and a collection tank, with the serpentine condenser located at the inlet of the collection tank.

4. The system for coupled carbon dioxide capture and in-situ methanolization according to claim 1, characterized in that, The nitrogen pipeline is connected to a first pressure reducing valve and a first flow valve, the flue gas pipeline is connected to a second pressure reducing valve and a second flow valve, and the hydrogen pipeline is connected to a third pressure reducing valve and a third flow valve.

5. The system for coupled carbon dioxide capture and in-situ methanolization according to claim 1, characterized in that, The gas delivery and switching unit also includes a mixing tank, which is connected to the main pipeline.

6. The system for coupling carbon dioxide capture and in-situ methanolization according to claim 1, characterized in that, The particle size of NaNO3-modified MgO in the composite material is 0.2–0.3 μm, and the particle size of zinc oxide-zirconia bimetallic oxide in the composite material is 0.1–0.2 μm.

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