Device system and method for preparing methanol through CO2 hydrogenation driven by new energy

Abstract

The invention provides a device system and method for preparing methanol through CO2 hydrogenation driven by new energy. The device system comprises a photovoltaic photo-thermal driving unit, an electrolyzed water hydrogen supply unit, a CO2 supply unit and a plasma coupling catalytic synthesis unit. The photovoltaic photo-thermal driving unit is matched with the water electrolysis hydrogen production unit and the plasma coupling catalytic synthesis unit, the multi-stage coupling technical means is adopted, overall combined heat and power generation is achieved, electric energy and heat energy needed in the device system are driven by solar energy, the overall energy consumption of green methanol production is reduced, and the energy consumption is reduced. The problems of large equipment size, high pressure, high input cost, high operation and maintenance cost and the like in a methanol preparation system through coupling of electrolyzed water and CO2 thermocatalysis in the prior art are solved, the CO2 conversion rate and the CO selectivity are improved, and high economy and operability are achieved.

Description

Technical Field

[0001] The invention belongs to the field of methanol synthesis and renewable energy, and relates to a device system and method for producing methanol by hydrogenating CO2 driven by new energy. Background Art

[0002] In recent years, both at home and abroad, the green utilization of carbon resources has been focused on, and CCUS (carbon capture) has emerged. The conversion of CO2 into C1 chemicals has become the focus of attention. In CCUS technology, CO2 hydrogenation to methanol is particularly important, because methanol can not only serve as a downstream recovery product of CO2 in industrial waste gas, assuming the responsibility of negative carbon, but also serve as a transport medium for hydrogen, solving the difficulties of hydrogen transportation and storage. At the same time, methanol itself is also an efficient and clean liquid fuel that can replace traditional fossil energy, achieving three goals at one stroke.

[0003] Traditional industrial methanol production generally uses coal or natural gas to produce methanol, which involves the combustion of fossil energy. Coal-based methanol production of 1 ton of product requires 3.5 tons to 4.0 tons of CO2 emissions, which cannot take into account both efficiency and cleanliness. Therefore, it is contrary to the green methanol advocated now. Green methanol is to use large-scale renewable energy to generate electricity during the methanol production process, and basically does not emit CO2 during the production process, achieving zero carbon emissions.

[0004] At present, green methanol is still in its infancy. When designing green methanol routes, most companies do not consider whether the CO2 source is renewable and the efficiency and energy consumption of the methanol production process, making it impossible to achieve both cleanliness and efficiency throughout the process.

[0005] In addition, the current integrated system of hydrogen production by water electrolysis and green methanol synthesis coupling generally has the following technical difficulties: direct hydrogenation of CO2 to produce methanol is subject to thermodynamic limitations and has low efficiency, which forces a greater demand for hydrogen under the same methanol indicators and a larger circulating gas flow rate, which in turn makes the overall equipment investment cost too high.

[0006] In summary, there is an urgent need to provide a green synthesis device system and method for producing methanol by hydrogenation of CO2, which solves the problems of large equipment size, high pressure, high investment cost, high operation and maintenance cost (such as high electricity bill) existing in the system of electrolysis of water + CO2 thermal catalysis for producing methanol, and realizes low-energy, flexible and orderly conversion of CO2 to methanol. Summary of the invention

[0007] The purpose of the present invention is to provide a device system and method for producing methanol by hydrogenation of CO2 driven by new energy. By matching a photovoltaic and photothermal driving unit with a water electrolysis hydrogen production unit and a plasma coupled catalytic synthesis unit, and adopting a multi-stage coupling technical means, overall cogeneration of heat and power is achieved. The electric energy and thermal energy required in the device system are driven by solar energy, which reduces the overall energy consumption of green methanol production. It solves the problems of large equipment size, high pressure, high investment cost, high operation and maintenance cost in the prior art system for producing methanol by water electrolysis coupled with CO2 thermal catalysis, while improving the CO2 conversion rate and CO selectivity, and has high economy and operability.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a device system for producing methanol by hydrogenation of CO2 driven by new energy, the device system comprising a photovoltaic thermal drive unit, a water electrolysis hydrogen supply unit, a CO2 supply unit, and a plasma coupled catalytic synthesis unit;

[0010] The photovoltaic thermal drive unit includes a light concentrator, a photovoltaic cell, a heat collector, a DC / AC converter, an electric storage device and a heat storage device;

[0011] The photovoltaic and thermal driving unit is used to provide electrical energy and thermal energy to the water electrolysis hydrogen supply unit and the plasma coupled catalytic synthesis unit;

[0012] The water electrolysis hydrogen supply unit is used to provide H2 for the plasma coupled catalytic synthesis unit;

[0013] The CO2 supply unit is used to provide CO2 for the plasma coupled catalytic synthesis unit;

[0014] The plasma coupled catalytic synthesis unit is used to pre-react CO2 and H2 in a plasma array to generate a synthesis gas containing CO, CO2 and H2, which enters a catalytic synthesis device and generates methanol through a catalytic reaction.

[0015] The device system provided by the present invention drives the water electrolysis hydrogen production unit to produce hydrogen through a photovoltaic thermal drive unit, which is mixed with CO2 provided by a CO2 supply unit and then introduced into a plasma coupled catalytic synthesis unit, and cooperates with the photovoltaic thermal drive unit to provide electricity and heat, reacts in a plasma array to generate synthesis gas, and then enters a catalytic synthesis device to react to generate methanol.

[0016] It is worth mentioning that the present invention realizes overall cogeneration of heat and power by matching a photovoltaic thermal drive unit with a water electrolysis hydrogen production unit and a plasma-coupled catalytic synthesis unit, and adopts multi-stage coupling technical means. The electrical energy and thermal energy required in the device system are driven by solar energy, which reduces the overall energy consumption of green methanol production and solves the problems of large equipment size, high pressure, high investment cost, and high operation and maintenance cost in the prior art system for producing methanol by water electrolysis coupled with CO2 thermal catalysis.

[0017] It is worth noting that the plasma-coupled catalytic synthesis unit adopted in the present invention uses a plasma array in combination with thermal catalysis to carry out the reaction path of CO2→CO→methanol. Compared with the traditional direct hydrogenation of CO2 to produce methanol, it has better single-pass conversion performance. Under the cycle condition, this technical path greatly reduces the overall circulating gas flow of methanol synthesis, prompting a reduction in the scale of the catalytic synthesis device, but at the same time it requires more hydrogen. Therefore, the front end of the present invention is matched with a water electrolysis hydrogen production unit to reduce the additional energy consumption due to the increased demand for hydrogen production.

[0018] As a preferred technical solution of the present invention, the photovoltaic cell is located below the light concentrator and above the heat collector.

[0019] Preferably, the concentrating device is used to focus solar radiation and send it to the light-receiving surface of the photovoltaic cell.

[0020] Preferably, the heat collection device is used to absorb solar energy not utilized by photovoltaic cells and convert the solar energy into thermal energy.

[0021] Preferably, the output end of the heat collecting device is connected to the input end of the heat storage device, and a heat transfer medium (flowing cooling water) is arranged in the connected pipeline.

[0022] Preferably, the output end of the heat storage device is independently connected to the heat energy input end of the water electrolysis hydrogen supply unit and the heat energy input end of the catalytic synthesis device.

[0023] It is worth mentioning that the concentrating device focuses sunlight on the photovoltaic cells, and the solar energy is converted into electrical energy through the photovoltaic effect. The generated direct current is converted into alternating current through the DC / AC conversion device and supplied to the SOEC electrolyzer and plasma array. If the SOEC electrolyzer and plasma array are not working, the electrical energy can be transmitted to the power storage device; the heat collection device absorbs the excess heat caused by the high-intensity radiation on the photovoltaic cells, and the heat circulates in the pipeline through the heat transfer medium and is transmitted to the heat storage device. Then the heat in the heat storage device is supplied to the SOEC electrolyzer and catalytic synthesis device.

[0024] Preferably, a cold storage tank and a heat storage tank are independently provided in the heat storage device.

[0025] In the present invention, the heat storage medium of the heat storage device is molten salt, and the composition of the molten salt is 60% sodium nitrate and 40% potassium nitrate. The heat storage device is provided with a cold storage tank and a heat storage tank, which store molten salt with a lower temperature and molten salt with a higher temperature respectively.

[0026] In the present invention, the working principle of the heat storage device is as follows: heat is transferred to molten salt through a heat collecting device or a SOFC fuel cell, the molten salt is heated in a heat exchanger, the temperature rises and flows into a heat storage tank for storage, the molten salt in the heat storage tank is kept at a high temperature, and heat can be extracted at any time when needed; when heat is needed, the hot molten salt flows out of the heat storage tank, and the heat is transferred to a working medium, such as water vapor, through a heat exchanger for heating; then the cooled molten salt flows back to the cold storage tank, waiting to be reheated, the molten salt in the cold storage tank is reheated in the next cycle, and enters the heat storage tank again, thereby realizing the recycling of heat.

[0027] Preferably, the output end of the photovoltaic cell is independently connected to the input end of the power storage device and the input end of the DC / AC conversion device.

[0028] Preferably, the output terminal of the power storage device is connected to the input terminal of the DC / AC conversion device.

[0029] Preferably, the output end of the DC / AC conversion device is independently connected to the power input end of the water electrolysis hydrogen supply unit and the power input end of the plasma array.

[0030] As a preferred technical solution of the present invention, the focusing device is a fluorescent focusing device.

[0031] It is worth mentioning that the focusing device adopts a fluorescent focusing design, which can absorb scattered light and still have power output in cloudy days or in environments without direct sunlight, greatly increasing the stability of the device system.

[0032] Preferably, the light focusing device comprises a substrate, a fluorescent layer and a protective layer which are stacked.

[0033] Preferably, the substrate comprises organic glass.

[0034] In the present invention, the organic glass is transparent and has a high refractive index.

[0035] Preferably, the thickness of the fluorescent layer is 5-20 μm, for example, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 16 μm or 18 μm, etc., but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0036] In the present invention, the coating method of the fluorescent layer includes: dispersing CdS@CdSe quantum dots in octane, using a spraying device to evenly spray the CdS@CdSe quantum dot solution onto a substrate, obtaining a CdS@CdSe quantum dot fluorescent layer of a desired thickness by multiple spraying, and then drying the substrate to remove the solvent and solidify the coating.

[0037] Preferably, the material of the fluorescent layer includes CdS@CdSe quantum dots.

[0038] It is worth noting that the present invention uses CdS@CdSe quantum dots as the material of the fluorescent layer, whose emission spectrum is adjustable and whose absorption spectrum is wider than other materials, and which can capture solar energy more effectively; in addition, CdS@CdSe quantum dots have a core-shell structure, which can improve the stability of the quantum dots.

[0039] In the present invention, the preparation method of CdS@CdSe quantum dots comprises the following steps:

[0040] (1) CdO, oleic acid and octane are mixed and heated to 200°C under N2 protection to obtain a Cd complex solution, TOP (tri-n-octylphosphine)-Se solution is quickly injected into the Cd complex solution at a temperature of 200°C, and after the injection is completed, the solution is allowed to stand at a temperature of 240°C for 2 hours to obtain a crude CdSe quantum dot product, and then the first reaction bottle is transferred to an ice water bath, cooled to room temperature and centrifuged, and finally the obtained precipitate is washed with ethanol at least 3 times to obtain CdSe quantum dots;

[0041] (2) Mix the CdSe quantum dots, oleic acid and octane obtained in step (1) and heat to 200°C under N2 protection to obtain a CdSe quantum dot solution, inject the CdO and TOP-S solutions into the CdSe quantum dot solution at 200°C for 20 min to obtain a crude CdSe@CdS quantum dot product with a core-shell structure, then transfer the second reaction bottle to an ice water bath, cool to room temperature and centrifuge, and finally wash the obtained precipitate with ethanol for at least 3 times to obtain CdS@CdSe quantum dots.

[0042] In the present invention, there is no specific limitation on the amount of each raw material added in the preparation of CdS@CdSe quantum dot materials, and those skilled in the art can select the amount according to actual needs.

[0043] Preferably, the thickness of the protective layer is 100-200 μm, for example, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 180 μm or 190 μm, etc., but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0044] Preferably, the material of the protective layer is silicon dioxide and titanium dioxide.

[0045] As a preferred technical solution of the present invention, the water electrolysis hydrogen supply unit includes a SOEC electrolyzer (solid oxide electrolyzer), an H2 compression device, an H2 storage tank, an O2 compression device and an O2 storage tank.

[0046] It is worth noting that the SOEC electrolyzer operates at high temperature (700-850°C), and the supplied water turns into water vapor at high temperature and is supplied from the anode side. Water molecules participate in the oxidation reaction at the anode, and generate oxygen and protons after losing electrons. The protons undergo a reduction reaction after passing through the electrolyte to the cathode, generating hydrogen at the cathode. Part of the hydrogen produced by electrolysis of water is used for hydrogen distribution in the subsequent plasma coupled catalytic synthesis unit, and the other part of the hydrogen is stored in the H2 storage tank after passing through the hydrogen purification device. The hydrogen in the H2 storage tank can be used in the SOFC fuel cell to convert chemical energy into electrical energy for power generation, thereby realizing the cogeneration of heat and power within the system.

[0047] It is worth noting that in order to ensure the stability of hydrogen provided by the SOEC electrolyzer hydrogen production device, the hydrogen outlet of the SOEC electrolyzer is also connected to an H2 storage tank, which can store a portion of hydrogen as a system buffer to avoid fluctuations in hydrogen supply and reduce the methanol yield. The specific control measures are: when the hydrogen content transported in the hydrogen outlet of the SOEC electrolyzer is excessive, the excess hydrogen is stored through the H2 storage tank; when the hydrogen content transported in the hydrogen outlet of the SOEC electrolyzer is insufficient, the hydrogen transported in the hydrogen outlet is supplemented by the H2 storage tank to ensure the relative stability of hydrogen and avoid affecting the methanol yield. Therefore, by setting up the H2 storage tank, not only can the stability of hydrogen supply be improved, but also when the power supply fluctuates, the SOEC electrolyzer reduces the load change, and the H2 storage tank can be used to supplement the methanol synthesis device with stable green hydrogen.

[0048] In the present invention, the specific structure of the SOEC electrolytic cell is not limited, wherein the SOEC electrolytic cell includes an electrolyte layer, a cathode, an anode, a current collector, a diaphragm and a thermal management system, the electrolyte layer material is yttrium-stabilized zirconia, the cathode material is a nickel-based ceramic composite material, the anode material is a perovskite-type lanthanum strontium cobalt iron oxide, and the current collector material is a nickel metal grid.

[0049] Preferably, the output end of the DC / AC conversion device and the output end of the heat storage device are independently connected to the SOEC electrolytic cell.

[0050] Preferably, the gas outlet of the SOEC electrolyzer is independently connected to the H2 compression device and the O2 compression device.

[0051] Preferably, the O2 compression device is connected to the O2 storage tank.

[0052] Preferably, the H2 compression device is connected to the H2 storage tank.

[0053] In the present invention, the H2 storage tank adopts pressure hydrogen storage.

[0054] Preferably, the CO2 supply unit comprises a CO2 capture device, a CO2 compression device and a CO2 storage tank which are connected in sequence.

[0055] As a preferred technical solution of the present invention, the plasma-coupled catalytic synthesis unit includes a raw gas storage tank, a plasma array, a booster assembly and a catalytic synthesis device which are connected in sequence.

[0056] In the present invention, the catalytic synthesis device is a conventional thermal catalytic synthesis reactor in the art.

[0057] Preferably, the H2 compression device, H2 storage tank, and CO2 storage tank are independently connected to the gas inlet of the plasma array.

[0058] Preferably, the output end of the DC / AC conversion device is connected to the power input end of the plasma array.

[0059] Preferably, the plasma array includes a plurality of dielectric barrier discharge reaction tubes.

[0060] In the present invention, the plasma array can promote the conversion of CO2 into CO. Under the action of the high-frequency AC electric field between the electrodes, the CO2 gas molecules in the discharge area are excited and dissociated after colliding with high-energy electrons, generating various active groups and rapidly forming filamentary discharge. In this discharge mode, CO is rapidly formed.

[0061] Preferably, the dielectric barrier discharge reaction tube is a composite tubular structure.

[0062] Preferably, the dielectric barrier discharge reaction tube comprises an outer electrode, an inner electrode, a plurality of bases, an air inlet manifold and an air outlet manifold.

[0063] Preferably, the outer electrode is sleeved on the outside of the inner electrode, and the outer electrode is a hollow structure.

[0064] Preferably, both ends of the dielectric barrier discharge reaction tube are fixed on a base.

[0065] In the present invention, the base is a flange base.

[0066] Preferably, the inner electrode is a cylindrical structure.

[0067] In the present invention, the outer electrode comprises a stainless steel round tube with a hollow structure, the inner electrode comprises a tungsten steel solid tube with a cylindrical structure, and both the outer electrode and the inner electrode are provided with insulating protection tubes, the outer electrode is grounded, and the inner electrode is connected to an AC power source via a cable; the outer electrode is specifically a tubular structure with a hollow portion made of a stainless steel mesh.

[0068] Preferably, the surface of the inner electrode is provided with threads.

[0069] It is worth mentioning that by providing a threaded structure on the surface of the inner electrode, tip discharge can be further formed on the basis of filamentary discharge, thereby enhancing the electric field strength and promoting CO2 conversion.

[0070] Preferably, the pitch of the thread is 0.8-1.2 mm, for example, it can be 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.05 mm, 1.1 mm or 1.15 mm, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0071] Preferably, a ring-shaped blocking medium layer is provided between the outer electrode and the inner electrode.

[0072] Preferably, the thickness of the blocking medium layer is 2.5-3.5 mm, for example, it can be 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3 mm, 3.1 mm, 3.2 mm, 3.3 mm or 3.4 mm, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0073] In the present invention, the material of the blocking dielectric layer includes quartz glass.

[0074] Preferably, the cavity formed between the inner electrode and the blocking dielectric layer is a discharge region.

[0075] Preferably, the distance between the inner electrode and the blocking dielectric layer is 1.2-1.8 mm, for example, it can be 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.55 mm, 1.6 mm or 1.7 mm, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0076] Preferably, the discharge zone is filled with α-Mo2C catalyst.

[0077] It is worth noting that filling the discharge zone with α-Mo2C catalyst helps to improve the CO selectivity in the plasma array pre-reaction and reduce the production of by-product methane.

[0078] In the present invention, the preparation method of the α-Mo2C catalyst comprises:

[0079] Mix deionized water and (NH4)6Mo7O 24 ·4H2O, and then sucrose was added thereto under stirring to obtain a gel, and then the sol was heated to 105°C at 5°C / min and kept warm for 12 h, and then the dried gel was heated to 500°C at 5°C / min in a mixed atmosphere of argon and hydrogen (H2 accounted for 10%, the total flow rate was 100sccm) and kept warm for 72 h to obtain an α-Mo2C catalyst.

[0080] In the present invention, the ratio of the raw materials in the preparation of the α-Mo2C catalyst is not specifically limited, and those skilled in the art can select it according to actual needs.

[0081] Preferably, the average particle size of the α-Mo2C catalyst is 40-60 mesh.

[0082] Preferably, the discharge area is also provided with a thermocouple.

[0083] In the present invention, the thermocouple is used to detect the temperature inside the dielectric barrier discharge reaction tube.

[0084] Preferably, the length of the discharge zone is 80-120 mm, for example, 85 mm, 90 mm, 95 mm, 100 mm, 105 mm, 110 mm or 115 mm, etc., but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0085] Preferably, both sides of the barrier medium layer are independently connected to an intake manifold and an outlet manifold, and both the intake manifold and the outlet manifold are connected to the discharge area.

[0086] In the present invention, the intake manifold is the inlet of the raw gas, and the outlet manifold is discharged into the exhaust gas storage tank through the exhaust pipeline.

[0087] As a preferred technical solution of the present invention, the boosting assembly includes several stages of boosting devices.

[0088] Preferably, the boosting assembly comprises a diaphragm pump, a first boosting pump and a second boosting pump which are connected in sequence.

[0089] Preferably, the output end of the heat storage device is connected to the heat energy input end of the catalytic synthesis device.

[0090] Preferably, the catalytic synthesis device is filled with CuO-ZnO-Al2O3 catalyst.

[0091] Preferably, the average particle size of the CuO-ZnO-Al2O3 catalyst is 20-40 meshes.

[0092] Preferably, the CuO-ZnO-Al2O3 catalyst is a hydrotalcite structure.

[0093] In the present invention, the preparation method of the CuO-ZnO-Al2O3 catalyst comprises:

[0094] Mix 5.33g Cu(NO)2·3H2O, 3.28g Zn(NO3)2·6H2O, 1.38g Al(NO 3)3 ·9H2O and deionized water to obtain a precursor solution, and then the precursor solution and the precipitant (a mixed solution of NaOH and Na2CO3 with a concentration of 1.5 mol / L) are added dropwise into 100 mL of deionized water at a rate of 2 seconds per drop, while stirring at 60°C and maintaining the pH of the solution at 7.5 to obtain a precursor precipitate, and stirring is continued for 0.5 h, and then the solution is allowed to stand at 75°C for 4 h, and then filtered, washed and vacuum dried at 95°C for 12 h in sequence to obtain a Cu-Zn-Al hydrotalcite precursor, and then the Cu-Zn-Al hydrotalcite precursor is ground and calcined at 400°C for 5 h to obtain a CuO-ZnO-Al2O3 catalyst.

[0095] As a preferred technical solution of the present invention, the device system also includes a SOFC fuel cell (solid oxide fuel cell).

[0096] Preferably, the input end of the SOFC fuel cell is connected to a H2 storage tank.

[0097] Preferably, the output end of the SOFC fuel cell is connected to the input end of the heat storage device.

[0098] The device system also includes a separation and purification unit and a methanol storage tank which are connected in sequence.

[0099] In the present invention, the separation and purification unit comprises a cooling device and a liquefaction device connected in sequence to achieve separation and purification of the reaction product.

[0100] Preferably, the catalytic synthesis device is connected to a separation and purification unit.

[0101] Preferably, the gas outlet of the separation and purification unit is connected to the gas inlet of the plasma array.

[0102] In a second aspect, the present invention provides a method for producing methanol by hydrogenation of CO2 driven by new energy, the method being carried out using the device system described in the first aspect, comprising the following steps:

[0103] (1) The solar energy is focused on the photovoltaic cell through the concentrator, and then the photovoltaic cell converts the solar energy into electrical energy. Part of the electrical energy is transmitted to the DC / AC conversion device, and the rest is transmitted to the power storage device. At the same time, the thermal collection device absorbs the unused solar energy of the photovoltaic cell and converts the solar energy into thermal energy, which is then transmitted to the thermal storage device;

[0104] (2) The water electrolysis hydrogen supply unit uses the electric energy provided by the DC / AC conversion device and the thermal energy provided by the heat storage device to carry out an oxidation-reduction reaction to produce H2;

[0105] (3) The CO2 provided by the CO2 supply unit and the H2 produced by the water electrolysis hydrogen supply unit in step (2) are introduced into the plasma array, and a pre-reaction is carried out using the electric energy provided by the DC / AC conversion device to obtain a synthesis gas containing CO, CO2 and H2. The obtained synthesis gas is pressurized and introduced into the catalytic synthesis device, and a catalytic reaction is carried out using the heat energy provided by the heat storage device to obtain crude methanol.

[0106] The method provided by the present invention pre-activates and converts CO2 under normal pressure of plasma, and the synthesis gas of CO, CO2 and H2 produced is more easily and efficiently catalytically synthesized into methanol in terms of kinetics and thermodynamics, thus overcoming the thermodynamic bottleneck of direct catalytic hydrogenation reaction of CO2. At the same time, the heat energy and electric energy required by the method are provided by a photovoltaic thermal drive unit.

[0107] As a preferred technical solution of the present invention, the redox reaction in step (2) is carried out in a SOEC electrolytic cell, a part of the generated H2 is transported to the plasma array, and the rest is transported to the H2 storage tank for storage.

[0108] Preferably, the current density of the SOEC electrolyzer is 3500-4000A / m 2 , for example, it can be 3600A / m 2 、3700A / m 2 、3800A / m 2 or 3900A / m 2 The above values ​​are not limited to the above values, and other values ​​within the above range are also applicable.

[0109] Preferably, the temperature of the SOEC electrolytic cell is 700-850°C, for example, it can be 720°C, 740°C, 750°C, 760°C, 780°C, 800°C, 820°C or 840°C, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0110] Preferably, a portion of the H2 in the H2 storage tank is delivered to the SOFC fuel cell, and the heat energy generated during operation is delivered to the heat storage device.

[0111] As a preferred technical solution of the present invention, in the plasma array of step (3), the molar ratio of CO2 and H2 is 1:(2.5-3.5), for example, it can be 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3, 1:3.1, 1:3.2 or 1:3.4, etc., but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0112] Preferably, in the plasma array of step (3), the flow rate of the raw gas is 80-120 mL / min, for example, it can be 85 mL / min, 90 mL / min, 95 mL / min, 100 mL / min, 105 mL / min, 110 mL / min or 115 mL / min, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0113] Preferably, in the plasma array of step (3), the input voltage is 30-40V, for example, it can be 31V, 32V, 33V, 34V, 35V, 36V, 37V, 38V or 39V, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0114] In the present invention, the temperature of the pre-reaction in step (3) is 150-200° C., but the temperature required for the pre-reaction is caused by discharge and does not require an external heat source.

[0115] Preferably, the synthesis gas in step (3) comprises the following components in terms of volume percentage: CO 15-20%, CO2 10-15%, H2 60-80%, and CH4 0.05-0.2%.

[0116] Preferably, the pressure increased in step (3) is 3-5 MPa, for example, 3.2 MPa, 3.5 MPa, 3.8 MPa, 4 MPa, 4.2 MPa, 4.5 MPa or 4.8 MPa, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0117] Preferably, the temperature of the catalytic reaction in step (3) is 220-260°C, for example, it can be 225°C, 230°C, 235°C, 240°C, 245°C, 250°C or 255°C, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0118] Preferably, after the crude methanol product in step (3) is separated into gas and liquid by a separation and purification unit, the gas is recycled into the plasma array, and the obtained methanol liquid is transported to a methanol storage tank.

[0119] Compared with the prior art, the present invention has the following beneficial effects:

[0120] (1) The device system and method for producing methanol by hydrogenation of CO2 driven by new energy provided by the present invention realizes overall cogeneration of heat and power by matching a photovoltaic and photothermal driving unit with a water electrolysis hydrogen production unit and a plasma coupled catalytic synthesis unit, and adopts a multi-stage coupling technical means. The required electrical energy and thermal energy are driven by solar energy, which reduces the overall energy consumption of green methanol production and solves the problems of large equipment volume, high pressure, high investment cost, and high operation and maintenance cost in the prior art system for producing methanol by water electrolysis coupled with CO2 thermal catalysis;

[0121] (2) The device system and method for producing methanol by hydrogenation of CO2 driven by new energy provided by the present invention adopts a plasma-coupled catalytic synthesis unit, which is used in combination with a plasma array and thermal catalysis. Through the reaction path of CO2→CO→methanol, its single-pass conversion performance is better, so that the overall circulating gas flow of methanol synthesis is greatly reduced, which promotes the reduction of the scale of the catalytic synthesis device, improves the CO2 conversion rate and CO selectivity, and has high economy and operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0122] Figure 1 A schematic diagram of the device system for producing methanol by hydrogenating CO2 driven by new energy provided in Example 1;

[0123] Figure 2 A schematic diagram of the structure of a dielectric barrier discharge reaction tube provided in Example 1;

[0124] Figure 3 A schematic diagram of a device system for producing methanol by hydrogenating CO2 driven by new energy provided in Example 3;

[0125] Among them, 1-light concentrating device, 2-photovoltaic cell, 3-heat collecting device, 4-DC / AC conversion device, 5-power storage device, 6-heat storage device, 7-SOEC electrolyzer, 8-H2 compression device, 9-H2 storage tank, 10-O2 compression device, 11-O2 storage tank, 12-CO2 capture device, 13-CO2 compression device, 14-CO2 storage tank, 15-plasma array, 16-boosting component, 17-catalytic synthesis device, 18-separation and purification unit, 19-methanol storage tank, 20-SOFC fuel cell; 21-inner electrode, 22-flange seat, 23-intake manifold, 24-discharge zone, 25-outer electrode, 26-barrier medium layer, 27-exhaust manifold. DETAILED DESCRIPTION

[0126] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0127] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0128] The specific embodiment of the present invention provides a new energy driven CO2 hydrogenation to methanol device system, the device system includes a photovoltaic thermal drive unit, a water electrolysis hydrogen supply unit, a CO2 supply unit, and a plasma coupled catalytic synthesis unit;

[0129] The photovoltaic thermal drive unit includes a light concentrator, a photovoltaic cell, a heat collector, a DC / AC converter, an electric storage device and a heat storage device;

[0130] The photovoltaic and thermal driving unit is used to provide electrical energy and thermal energy to the water electrolysis hydrogen supply unit and the plasma coupled catalytic synthesis unit;

[0131] The water electrolysis hydrogen supply unit is used to provide H2 for the plasma coupled catalytic synthesis unit;

[0132] The CO2 supply unit is used to provide CO2 for the plasma coupled catalytic synthesis unit;

[0133] The plasma coupled catalytic synthesis unit is used to pre-react CO2 and H2 in a plasma array to generate a synthesis gas containing CO, CO2 and H2, which enters a catalytic synthesis device and generates methanol through a catalytic reaction.

[0134] In the following embodiments and comparative examples, there is no specific limitation on the number of dielectric barrier discharge reaction tubes, and those skilled in the art may select the number according to actual conditions.

[0135] Example 1

[0136] This embodiment provides a new energy-driven CO2 hydrogenation to methanol device system (such as Figure 1 As shown), the device system includes a photovoltaic thermal drive unit, a water electrolysis hydrogen supply unit, a CO2 supply unit, and a plasma coupled catalytic synthesis unit;

[0137] The photovoltaic thermal drive unit comprises a light concentrator 1, a photovoltaic cell 2, a heat collector 3, a DC / AC converter 4, a power storage device 5 and a heat storage device 6;

[0138] The photovoltaic cell 2 is located below the light concentrator 1 and above the heat collecting device 3; the light concentrator 1 is used to focus solar radiation and send it to the light-receiving surface of the photovoltaic cell 2; the heat collecting device 3 is used to absorb the unused solar energy of the photovoltaic cell 2 and convert the solar energy into heat energy; the output end of the heat collecting device 3 is connected to the input end of the heat storage device 6, and a heat transfer medium is arranged in the connected pipeline; the heat storage device 6 is independently provided with a cold storage tank and a heat storage tank; the output end of the photovoltaic cell 2 is independently connected to the input end of the power storage device 5 and the input end of the DC / AC conversion device 4; the output end of the power storage device 5 is connected to the input end of the DC / AC conversion device 4;

[0139] The electrolytic water hydrogen supply unit comprises a SOEC electrolyzer 7, a H2 compression device 8, a H2 storage tank 9, an O2 compression device 10 and an O2 storage tank 11;

[0140] The output end of the DC / AC conversion device 4 and the output end of the heat storage device 6 are independently connected to the SOEC electrolyzer 7; the gas outlet of the SOEC electrolyzer 7 is independently connected to the H2 compression device 8 and the O2 compression device 10; the O2 compression device 10 is connected to the O2 storage tank 11; the H2 compression device 8 is connected to the H2 storage tank 9; the CO2 supply unit includes a CO2 capture device 12, a CO2 compression device 13 and a CO2 storage tank 14 connected in sequence;

[0141] The plasma-coupled catalytic synthesis unit comprises a plasma array 15, a booster assembly 16 and a catalytic synthesis device 17 connected in sequence;

[0142] The H2 compression device 8, the H2 storage tank 9, and the CO2 storage tank 14 are independently connected to the gas inlet of the plasma array 15; the output end of the DC / AC conversion device 4 is connected to the power input end of the plasma array 15;

[0143] The plasma array 15 includes a plurality of dielectric barrier discharge reaction tubes; the dielectric barrier discharge reaction tubes (such as Figure 2 The dielectric barrier discharge reaction tube is a composite tubular structure; the dielectric barrier discharge reaction tube comprises an outer electrode 25, an inner electrode 21, two flange seats 22, an inlet manifold 23 and an outlet manifold 27; both ends of the dielectric barrier discharge reaction tube are fixed on the flange seat 22;

[0144] The outer electrode 25 is sleeved on the outside of the inner electrode 21, and the outer electrode 25 is a stainless steel round tube with a hollow structure; the inner electrode 21 is a tungsten steel solid tube with a cylindrical structure, and both the outer electrode 25 and the inner electrode 21 are sleeved with an insulating protection tube, the outer electrode is grounded, and the inner electrode is connected to an AC power supply through a cable; the surface of the inner electrode 21 is provided with a thread; the pitch of the thread is 1 mm;

[0145] An annular blocking dielectric layer 26 is provided between the outer electrode 25 and the inner electrode 21; the thickness of the blocking dielectric layer 26 is 3 mm; the cavity formed between the inner electrode 21 and the blocking dielectric layer 26 is the discharge zone 24; the distance between the inner electrode 21 and the blocking dielectric layer 26 is 1.5 mm; the discharge zone 24 is filled with an α-Mo2C catalyst with an average particle size of 40-50 mesh; the discharge zone 24 is also provided with a thermocouple; the length of the discharge zone 24 is 100 mm; the two sides of the blocking dielectric layer 26 are independently connected to the intake manifold 23 and the outlet manifold 27, and the intake manifold 23 and the outlet manifold 27 are both connected to the discharge zone 24; the intake manifold is the inlet of the raw gas, and the outlet manifold is discharged into the exhaust gas storage tank through the exhaust pipeline;

[0146] The boosting assembly 16 includes a diaphragm pump, a first boosting pump and a second boosting pump connected in sequence; the output end of the heat storage device 6 is connected to the heat energy input end of the catalytic synthesis device 17; the catalytic synthesis device 17 is filled with a CuO-ZnO-Al2O3 catalyst with a hydrotalcite structure and an average particle size of 20-30 mesh;

[0147] The device system also includes a separation and purification unit 18 and a methanol storage tank 19 which are connected in sequence; the catalytic synthesis device 17 is connected to the separation and purification unit 18; and the gas outlet of the separation and purification unit 18 is connected to the gas inlet of the plasma array.

[0148] Example 2

[0149] This embodiment provides a new energy driven CO2 hydrogenation to methanol device system, which further defines on the basis of embodiment 1:

[0150] The focusing device is a fluorescent focusing device; the focusing device comprises a stacked substrate, a fluorescent layer and a protective layer; the substrate is organic glass; the thickness of the fluorescent layer is 5-20 μm; the material of the fluorescent layer is CdS@CdSe quantum dots with a core-shell structure; the thickness of the protective layer is 100-200 μm; the material of the protective layer is silicon dioxide and titanium dioxide.

[0151] Example 3

[0152] This embodiment provides a new energy-driven CO2 hydrogenation to methanol device system (such as Figure 3 As shown), further defined on the basis of Example 2:

[0153] The device system further includes a SOFC fuel cell 20 ; the input end of the SOFC fuel cell 20 is connected to the H2 storage tank 9 ; the output end of the SOFC fuel cell 20 is connected to the input end of the heat storage device 6 .

[0154] After the device system provided in this embodiment is put into mass production, based on a methanol production of at least 3,000 tons / year and an annual utilization hour of 6,480 hours for the methanol production line, it uses 1,070 tons / year of green hydrogen, and the by-product oxygen production is 8,553 tons / year, and can avoid the emission of about 9,435 tons / year of carbon dioxide.

[0155] Example 4

[0156] This embodiment provides a new energy driven CO2 hydrogenation to methanol device system, except that no H2 storage tank is provided, that is, the H2 compression device is directly connected to the gas inlet of the plasma array; other conditions are the same as those in Example 2.

[0157] Example 5

[0158] This embodiment provides a new energy driven CO2 hydrogenation to methanol device system, except that the surface of the inner electrode is not provided with threads; other conditions are the same as those of Example 2.

[0159] Example 6

[0160] This embodiment provides a device system for producing methanol by hydrogenating CO2 driven by new energy, except that the distance between the inner electrode and the barrier dielectric layer is 0.5 mm; other conditions are the same as those in Example 2.

[0161] Example 7

[0162] This embodiment provides a device system for producing methanol by hydrogenating CO2 driven by new energy, except that the distance between the inner electrode and the barrier dielectric layer is 2.5 mm; other conditions are the same as those in Example 2.

[0163] Example 8

[0164] This embodiment provides a new energy driven CO2 hydrogenation to methanol device system, except that the discharge zone is not filled with an α-Mo2C catalyst with an average particle size of 40-50 mesh; other conditions are the same as those in Example 2.

[0165] Comparative Example 1

[0166] This comparative example provides a device system for producing methanol by hydrogenation of CO2. The production of methanol by hydrogenation of CO2 is carried out only in a catalytic synthesis device, which is subsequently connected in sequence with a separation and purification unit and a methanol storage tank.

[0167] Comparative Example 2

[0168] This comparative example provides a device system for producing methanol by hydrogenating CO2, in which H2 is provided by an alkaline electrolyzer, and the production of methanol by hydrogenating CO2 is carried out in a catalytic synthesis device, which is subsequently connected in sequence to a separation and purification unit and a methanol storage tank.

[0169] Application Example 1

[0170] This application example provides a method for producing methanol by hydrogenation of CO2 driven by new energy, which is carried out using the device system provided in Example 1, and includes the following steps:

[0171] (1) The solar energy is focused on the photovoltaic cell through the concentrator, and then the photovoltaic cell converts the solar energy into electrical energy. Part of the electrical energy is transmitted to the DC / AC conversion device, and the rest is transmitted to the power storage device. At the same time, the thermal collection device absorbs the unused solar energy of the photovoltaic cell and converts the solar energy into thermal energy, which is then transmitted to the thermal storage device;

[0172] (2) The electric energy provided by the DC / AC converter and the heat energy provided by the heat storage device are used at a current density of 4000A / m 2 , a redox reaction is carried out in a SOEC electrolyzer at a temperature of 750°C, a part of the generated H2 is transported to the plasma array, and the rest is transported to the H2 storage tank for storage;

[0173] (3) CO2 provided by the CO2 supply unit and H2 produced by the SOEC electrolyzer in step (2) are introduced into the plasma array at a molar ratio of 1:3 at a total gas flow rate of 100 mL / min, and a pre-reaction is carried out at a pressure of 0.1 MPa and an input voltage of 35 V using the electric energy provided by the DC / AC conversion device to obtain a synthesis gas containing CO, CO2 and H2. The obtained synthesis gas is pressurized to 3.0 MPa and then introduced into the catalytic synthesis device, and a catalytic reaction is carried out at a temperature of 240° C. using the heat energy provided by the heat storage device to obtain crude methanol. After the crude methanol is separated into gas and liquid by the separation and purification unit, the gas is recycled to the plasma array, and the obtained methanol liquid is transported to the methanol storage tank.

[0174] Application Example 2

[0175] This application example provides a method for producing methanol by hydrogenating CO2 driven by new energy. Except for applying the device system provided in Example 2, other conditions are the same as those in Application Example 1.

[0176] In this application example, the device system provided in Example 2 is used to improve the focusing performance, and power output is still available on cloudy days or in environments where sunlight is not directly emitted, thereby increasing the stability of the device system.

[0177] Application Example 3

[0178] This application example provides a method for producing methanol by hydrogenating CO2 driven by new energy. In addition to applying the device system provided in Example 3, the H2 in the H2 storage tank in step (2) is transported to the SOFC fuel cell, and the heat energy generated during operation is transported to the heat storage device. Other conditions are the same as those in Application Example 1.

[0179] In this application example, the device system provided in Example 3 is used to improve the thermal energy cycle performance and further enhance the cogeneration performance of the device system.

[0180] Application Example 4

[0181] This application example provides a method for producing methanol by hydrogenating CO2 driven by new energy. Except for applying the device system provided in Example 4, other conditions are the same as those in Application Example 1.

[0182] In this application example, the device system provided in Example 4 is used. Since no H2 storage tank is provided, the relative stability of hydrogen cannot be guaranteed. When the hydrogen production fluctuates, the methanol yield decreases, and hydrogen cannot be supplied to the SOFC fuel cell, which reduces the thermal energy cycle performance.

[0183] Application Examples 5-8

[0184] This application example provides a method for producing methanol by hydrogenating CO2 driven by new energy. Except for applying the device system provided in Examples 5-8, other conditions are the same as those in Application Example 1.

[0185] Comparative application example 1

[0186] This comparative application example provides a method for producing methanol by hydrogenating CO2. Except for using the device system provided in comparative example 1, other conditions are the same as those in application example 1.

[0187] Comparative Application Example 2

[0188] This comparative application example provides a method for producing methanol by hydrogenation of CO2, except that the device system provided in comparative example 2 is used and the current density of the alkaline electrolytic cell is 6000A / m 2 Except for this, all other conditions are the same as those in Application Example 1.

[0189] The CO2 conversion rate, methanol selectivity and yield of the methods provided in the above-mentioned Application Examples 1, 5-8 and Comparative Application Examples 1-2 were tested, and the results are shown in Table 1; in addition, the gas inlet and outlet flow rates in the plasma array during the methanol synthesis process of the above-mentioned Application Examples 1, 5-8 and Comparative Application Examples 1-2 were also tested, and the results are shown in Table 2.

[0190] Table 1

[0191]

[0192] Table 2

[0193]

[0194]

[0195] Wherein, the circulating gas in Table 2 is the gas separated in the separation and purification unit;

[0196] From Table 1 and Table 2, we can see that:

[0197] (1) The device system and method for producing methanol by hydrogenation of CO2 driven by new energy provided by the present invention realizes overall cogeneration of heat and power by matching a photovoltaic and photothermal driving unit with a water electrolysis hydrogen production unit and a plasma coupled catalytic synthesis unit, and adopts a multi-stage coupling technical means. The required electrical energy and thermal energy are driven by solar energy, which reduces the overall energy consumption of green methanol production. At the same time, the single-pass conversion performance of methanol synthesis is better, and the overall circulation flow rate in the methanol synthesis process is reduced;

[0198] (2) By comparing Application Example 1 with Application Example 5, it can be seen that when the inner electrode surface is not provided with threads, it is impossible to further form a tip discharge on the basis of the filamentary discharge, and thus the electric field strength cannot be enhanced, the CO2 conversion rate decreases, and at the same time, due to the decrease in the single-pass conversion performance, the overall circulating gas flow rate increases, and the cost increases;

[0199] (3) By comparing Application Example 1 with Application Examples 6-7, it can be seen that the spacing of the discharge zones is proportional to the CO2 conversion performance. The shorter the spacing, the higher the discharge intensity and the better the conversion performance. However, in actual application, the preparation of short-spacing plasma arrays is difficult, the array material requirements are high, and the production cost is high. When the spacing of the discharge zones is too long, the reduced electric field intensity will be low, making it difficult to break through the gap, thereby affecting the normal operation of the plasma system.

[0200] (4) By comparing Application Example 1 and Comparative Application Examples 1-2, it can be seen that when CO2 hydrogenation to methanol is carried out only in a catalytic synthesis device and plasma array coupling is not used, the single-pass conversion performance of methanol decreases and the gas circulation volume of the overall device system increases, resulting in an increase in the volume of the required equipment and excessively high costs.

[0201] The costs of the plasma-coupled catalytic synthesis unit in Application Example 1 and the catalytic synthesis device in Comparative Application Example 1 during the development and operation process are compared, and the results are shown in Table 3.

[0202] Table 3

[0203]

[0204] It can be seen from Table 3 that when only a catalytic synthesis unit is used to produce methanol by hydrogenation of CO2, its cost is much higher than that of a plasma-coupled catalytic synthesis unit, mainly because the addition of plasma greatly reduces the gas circulation volume of the overall system. Among them, the cost of the catalytic synthesis unit is calculated using the following formula:

[0205]

[0206] In the above formula: C is the net installation cost (10,000 yuan); C0 is the reference cost (10,000 yuan); P is the total inlet gas flow rate of the catalytic synthesis device (kg / h), P0 is the reference gas flow rate of the catalytic synthesis device (kg / h); f is the proportional factor (greater than 0).

[0207] According to the above formula, the lower the total inlet gas flow rate of the catalytic synthesis device, the lower its cost. In addition, since the plasma array device itself is simple in design, its cost is relatively small, and its additional electricity costs come from renewable energy generation, so the operation and maintenance costs of the plasma array device are not high.

[0208] The overall efficiency and energy consumption during the operation of the electrolytic cells in the above-mentioned Application Example 1 and Comparative Application Example 2 are compared, and the results are shown in Table 4.

[0209] Table 4

[0210] Power efficiency (%) <![CDATA[Electric energy consumption (kWh / kg H2 )]]> <![CDATA[Thermal energy consumption (kWh / kg H2 )]]> Application Example 1 98 39 5.9 Comparative Application Example 2 70 55.8 0

[0211] It can be seen from Table 4 that if alkaline electrolyzers are used to produce hydrogen, not only is the power consumption high, but the power efficiency is also low, making the overall investment cost too high.

[0212] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A new energy-driven CO2 hydrogenation to methanol device system, characterized in that: The device system includes a photovoltaic and thermal driving unit, a water electrolysis hydrogen supply unit, a CO2 supply unit, and a plasma coupled catalytic synthesis unit; The photovoltaic thermal drive unit includes a light concentrator, a photovoltaic cell, a heat collector, a DC / AC converter, an electric storage device and a heat storage device; The photovoltaic and thermal driving unit is used to provide electrical energy and thermal energy to the water electrolysis hydrogen supply unit and the plasma coupled catalytic synthesis unit; The water electrolysis hydrogen supply unit is used to provide H2 for the plasma coupled catalytic synthesis unit; The CO2 supply unit is used to provide CO2 for the plasma coupled catalytic synthesis unit; The plasma coupled catalytic synthesis unit is used to pre-react CO2 and H2 in a plasma array to generate a synthesis gas containing CO, CO2 and H2, which enters a catalytic synthesis device and generates methanol through a catalytic reaction.

2. The device system according to claim 1, characterized in that: The photovoltaic cell is located below the light concentrator and above the heat collector; Preferably, the light concentrator is used to focus solar radiation and send it to the light-receiving surface of the photovoltaic cell; Preferably, the heat collection device is used to absorb solar energy not utilized by photovoltaic cells and convert the solar energy into thermal energy; Preferably, the output end of the heat collecting device is connected to the input end of the heat storage device, and a heat transfer medium is provided in the connected pipeline; Preferably, the output end of the heat storage device is independently connected to the heat energy input end of the water electrolysis hydrogen supply unit and the heat energy input end of the catalytic synthesis device; Preferably, the heat storage device is independently provided with a cold storage tank and a heat storage tank; Preferably, the output end of the photovoltaic cell is independently connected to the input end of the power storage device and the input end of the DC / AC conversion device; Preferably, the output terminal of the power storage device is connected to the input terminal of the DC / AC conversion device; Preferably, the output end of the DC / AC conversion device is independently connected to the power input end of the water electrolysis hydrogen supply unit and the power input end of the plasma array.

3. The device system according to claim 1 or 2, characterized in that: The light focusing device is a fluorescent light focusing device; Preferably, the light focusing device comprises a substrate, a fluorescent layer and a protective layer which are stacked; Preferably, the substrate comprises organic glass; Preferably, the thickness of the fluorescent layer is 5-20 μm; Preferably, the material of the fluorescent layer includes CdS@CdSe quantum dots; Preferably, the thickness of the protective layer is 100-200 μm; Preferably, the material of the protective layer is silicon dioxide and titanium dioxide.

4. The device system according to any one of claims 1 to 3, characterized in that: The water electrolysis hydrogen supply unit comprises a SOEC electrolyzer, a H2 compression device, a H2 storage tank, an O2 compression device and an O2 storage tank; Preferably, the output end of the DC / AC conversion device and the output end of the heat storage device are independently connected to the SOEC electrolytic cell; Preferably, the gas outlet of the SOEC electrolyzer is independently connected to the H2 compression device and the O2 compression device; Preferably, the O2 compression device is connected to the O2 storage tank; Preferably, the H2 compression device is connected to the H2 storage tank; Preferably, the CO2 supply unit comprises a CO2 capture device, a CO2 compression device and a CO2 storage tank which are connected in sequence.

5. The device system according to any one of claims 1 to 4, characterized in that: The plasma-coupled catalytic synthesis unit comprises a plasma array, a booster assembly and a catalytic synthesis device connected in sequence; Preferably, the H2 compression device, H2 storage tank, and CO2 storage tank are independently connected to the gas inlet of the plasma array; Preferably, the output end of the DC / AC conversion device is connected to the power input end of the plasma array; Preferably, the plasma array comprises a plurality of dielectric barrier discharge reaction tubes; Preferably, the dielectric barrier discharge reaction tube is a composite tubular structure; Preferably, the dielectric barrier discharge reaction tube comprises an outer electrode, an inner electrode, a plurality of bases, an inlet manifold and an outlet manifold; Preferably, the outer electrode is sleeved on the outside of the inner electrode, and the outer electrode is a hollow structure; Preferably, both ends of the dielectric barrier discharge reaction tube are fixed on a base; Preferably, the inner electrode is a cylindrical structure; Preferably, the surface of the inner electrode is provided with threads; Preferably, the pitch of the thread is 0.8-1.2 mm; Preferably, a ring-shaped blocking medium layer is provided between the outer electrode and the inner electrode; Preferably, the thickness of the barrier medium layer is 2.5-3.5 mm; Preferably, the cavity formed between the inner electrode and the blocking dielectric layer is a discharge region; Preferably, the distance between the inner electrode and the barrier dielectric layer is 1.2-1.8 mm; Preferably, the discharge zone is filled with α-Mo2C catalyst; Preferably, the average particle size of the α-Mo2C catalyst is 40-60 mesh; Preferably, the discharge area is also provided with a thermocouple; Preferably, the length of the discharge zone is 80-120 mm; Preferably, both sides of the barrier medium layer are independently connected to an intake manifold and an outlet manifold, and both the intake manifold and the outlet manifold are connected to the discharge area.

6. The device system according to claim 5, characterized in that: The boost assembly includes several stages of boosting devices; Preferably, the boosting assembly comprises a diaphragm pump, a first boosting pump and a second boosting pump connected in sequence; Preferably, the output end of the heat storage device is connected to the heat energy input end of the catalytic synthesis device; Preferably, the catalytic synthesis device is filled with a CuO-ZnO-Al2O3 catalyst; Preferably, the average particle size of the CuO-ZnO-Al2O3 catalyst is 20-40 mesh; Preferably, the CuO-ZnO-Al2O3 catalyst is a hydrotalcite structure.

7. The device system according to any one of claims 1 to 6, characterized in that: The device system also includes a SOFC fuel cell; Preferably, the input end of the SOFC fuel cell is connected to a H2 storage tank; Preferably, the output end of the SOFC fuel cell is connected to the input end of the heat storage device; Preferably, the device system further comprises a separation and purification unit and a methanol storage tank connected in sequence; Preferably, the catalytic synthesis device is connected to a separation and purification unit; Preferably, the gas outlet of the separation and purification unit is connected to the gas inlet of the plasma array.

8. A method for producing methanol by hydrogenation of CO2 driven by new energy, characterized in that: The method is performed using the device system according to any one of claims 1 to 7, comprising the following steps: (1) The solar energy is focused on the photovoltaic cell through the concentrator, and then the photovoltaic cell converts the solar energy into electrical energy. Part of the electrical energy is transmitted to the DC / AC conversion device, and the rest is transmitted to the power storage device. At the same time, the thermal collection device absorbs the unused solar energy of the photovoltaic cell and converts the solar energy into thermal energy, which is then transmitted to the thermal storage device; (2) The water electrolysis hydrogen supply unit uses the electric energy provided by the DC / AC conversion device and the thermal energy provided by the heat storage device to carry out an oxidation-reduction reaction to produce H2; (3) The CO2 provided by the CO2 supply unit and the H2 produced by the water electrolysis hydrogen supply unit in step (2) are introduced into the plasma array, and a pre-reaction is carried out using the electric energy provided by the DC / AC conversion device to obtain a synthesis gas containing CO, CO2 and H2. The obtained synthesis gas is pressurized and introduced into the catalytic synthesis device, and a catalytic reaction is carried out using the heat energy provided by the heat storage device to obtain crude methanol.

9. The method according to claim 8, characterized in that The redox reaction in step (2) is carried out in a SOEC electrolyzer, a portion of the generated H2 is transported to a plasma array, and the remaining portion is transported to a H2 storage tank for storage; Preferably, the current density of the SOEC electrolyzer is 3500-4000A / m 2 ; Preferably, the temperature of the SOEC electrolyzer is 700-850°C; Preferably, a portion of the H2 in the H2 storage tank is delivered to the SOFC fuel cell, and the heat energy generated by the operation is delivered to the heat storage device.

10. The method according to claim 8 or 9, characterized in that: In the plasma array of step (3), the molar ratio of CO2 to H2 is 1:(2.5-3.5); Preferably, in the plasma array of step (3), the feed gas flow rate is 80-120 mL / min; Preferably, in the plasma array of step (3), the input voltage is 30-40V; Preferably, the synthesis gas in step (3) comprises the following components by volume percentage: CO 15-20%, CO2 10-15%, H2 60-80%, CH4 0.05-0.2%; Preferably, the pressure in step (3) is increased to 3-5 MPa; Preferably, the temperature of the catalytic reaction in step (3) is 220-260°C; Preferably, after the crude methanol product in step (3) is separated into gas and liquid by a separation and purification unit, the gas is recycled into the plasma array, and the obtained methanol liquid is transported to a methanol storage tank.

Images