Dimethyl ether preparation system and preparation method thereof

Abstract

The invention discloses a dimethyl ether preparation system and a preparation method thereof, and relates to the technical field of clean energy. The dimethyl ether preparation system comprises an air carbon dioxide trapping device, a gas-liquid separation device, a gas-liquid separation device, a gas-liquid separation device and a gas-liquid separation device, the hydrogen production device is used for preparing hydrogen; the mixing reactor is connected with the air carbon dioxide trapping device and the hydrogen production device and is used for mixing and reacting carbon dioxide and hydrogen; and the dimethyl ether collecting device is connected with the mixing reactor and is used for collecting dimethyl ether in the reaction gas. The dimethyl ether preparation method comprises the steps of carbon dioxide and hydrogen collection, mixed reaction, primary condensation, pressurization, secondary condensation and the like. Based on the technical scheme provided by the invention, not only can the energy consumption and carbon emission be reduced, but also the preparation efficiency of dimethyl ether can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of clean energy, and in particular to a dimethyl ether preparation system and a preparation method thereof. Background Art

[0002] With the continuous growth of the population and the intensification of the greenhouse effect, the global demand for carbon emission reduction and energy transformation is becoming increasingly urgent. Solar energy, as a clean, renewable energy source, has enormous development potential. However, the development of my country's renewable energy industry faces bottlenecks in grid absorption. In some regions, approximately 10% of clean electricity is wasted, involving various energy sources such as photovoltaics, wind power, and hydropower. How to utilize this green electricity that is not absorbed by the grid has become an urgent issue.

[0003] At present, there are many technologies that use green electricity to produce hydrogen energy, but hydrogen energy has poor safety and is difficult to store and transport. Dimethyl ether has higher stability than hydrogen energy, with a boiling point of -24.9°C, which is much higher than hydrogen energy, making it easy to store and transport. In addition, dimethyl ether can also be used as a clean fuel to replace gasoline and diesel, and can be used in automobile and ship engines, etc., and has good application prospects.

[0004] The existing method for producing dimethyl ether (DME) primarily involves coal gasification to generate syngas, which is then used to produce methanol. Finally, methanol is dehydrated to produce DME. This method has high carbon emissions, with each ton of DME emitting 3.0-3.5 tons of CO2 over its entire lifecycle, and its overall energy efficiency is only 45%-55%. This method not only produces high carbon emissions but also consumes a lot of energy and has relatively low production efficiency. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies and propose a dimethyl ether preparation system and preparation method thereof, so as to solve the technical problems of high carbon emissions and energy consumption and low preparation efficiency in the prior art of dimethyl ether preparation.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a dimethyl ether preparation system, comprising: Air carbon dioxide capture device, used to collect carbon dioxide from the air; A hydrogen production device for producing hydrogen; a mixing reactor connected to the air carbon dioxide capture device and the hydrogen production device, for mixing and reacting carbon dioxide and hydrogen; and The dimethyl ether collecting device is connected to the mixing reactor and is used to collect dimethyl ether in the reaction gas.

[0007] In some embodiments, the air carbon dioxide capture device comprises: Gas adsorption module, used to adsorb carbon dioxide from the air; a heating and desorption module, connected to the gas adsorption module and used to heat the gas adsorption module; and The carbon dioxide collection tank is connected to the heating desorption module and the mixing reactor, and is used to collect the desorbed carbon dioxide and supply carbon dioxide to the mixing reactor.

[0008] In some embodiments, the hydrogen production device comprises: electrolytic cell; an electrolysis unit, disposed in the electrolytic cell, for electrolyzing water to produce hydrogen; and A hydrogen collecting tank is connected to the gas outlets of the mixing reactor and the electrolyzer, and is used to collect hydrogen and supply hydrogen to the mixing reactor.

[0009] In some embodiments, the mixing reactor is a slurry bed reactor, and the slurry bed reactor comprises: Reactor housing; A reaction chamber is located inside the reactor shell, and a catalyst is arranged in the reaction chamber; a heating device, disposed on the reactor housing, for heating the reaction chamber; and A pressure control valve is provided on the reactor shell and communicated with the reaction chamber, and is used for controlling the pressure inside the reaction chamber.

[0010] In some embodiments, the reaction chamber includes: a gas phase mixing zone, located at the bottom of the reaction chamber, wherein a gas mixing layer is provided in the gas phase mixing zone for mixing reaction gases; and The gas-liquid-solid mixing reaction chamber is located above the gas phase mixing zone, and the catalyst is located in the gas-liquid-solid mixing reaction chamber for mixing and reacting with the reaction gas.

[0011] In some embodiments, a gas distribution plate is further provided in the reaction chamber. The gas distribution plate is located between the gas phase mixing zone and the gas-liquid-solid mixing reaction chamber, and a plurality of evenly distributed guide holes are provided on the gas distribution plate.

[0012] In some embodiments, a stirring blade is fixedly provided on the gas distribution plate; a stirring shaft and a stirring drive member are provided on the reactor shell, and two ends of the stirring shaft are respectively connected to the gas distribution plate and the stirring drive member.

[0013] In some embodiments, a methanol collecting device is further provided between the mixing reaction formula and the dimethyl ether collecting device, and the methanol collecting device comprises: a first condenser connected to the mixing reactor via a pipeline, and configured to condense the gas after the reaction and liquefy the methanol; and A methanol collecting tank is connected to the outlet of the first condenser through a pipeline and is used to collect liquefied methanol.

[0014] In some embodiments, the dimethyl ether collection device comprises: a first gas compressor, the first gas compressor being connected to the gas outlet of the methanol collection tank via a pipeline for achieving gas pressurization; a second condenser connected to the first gas compressor via a pipeline, for condensing gas and liquefying dimethyl ether; and A dimethyl ether collecting tank is connected to the gas outlet of the second condenser through a pipeline and is used to collect liquefied dimethyl ether.

[0015] In a second aspect, the present invention further provides a method for preparing dimethyl ether, which uses the above-mentioned dimethyl ether preparation system and comprises the following steps: S1, collect carbon dioxide and prepare hydrogen required for the reaction; S2, introducing carbon dioxide and hydrogen into a slurry bed reactor, so that the mixed gas reacts with the catalyst in the slurry bed reactor; S3, condensing the gas after the reaction to obtain liquefied methanol; S4. Pressurizing the gas after the reaction and performing secondary condensation to obtain liquefied dimethyl ether.

[0016] Compared to existing technologies, the dimethyl ether production system and method provided by the present invention collects carbon dioxide from the air using an air carbon dioxide capture device and produces hydrogen using a hydrogen production device. The carbon dioxide and hydrogen are mixed in a mixing reactor and react with a catalyst, and the dimethyl ether in the reaction gas is collected using a dimethyl ether collection device. This method abandons the traditional method of using coal to produce dimethyl ether and achieves a one-step synthesis of dimethyl ether, which not only reduces energy consumption and carbon emissions but also greatly improves the production efficiency of dimethyl ether. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is a schematic diagram of the overall structure of a dimethyl ether preparation system according to an embodiment of the present invention; Figure 2 is a schematic structural diagram of an air carbon dioxide capture device according to one embodiment of the present invention; Figure 3 It is a structural schematic diagram of a hydrogen production device in one embodiment of the present invention; Figure 4is a first structural schematic diagram of a slurry bed reactor in one embodiment of the present invention; Figure 5 2 is a schematic diagram of the second structure of a state bed reactor according to one embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of a gas mixing layer according to an embodiment of the present invention; Figure 7 is a schematic structural diagram of a gas distribution plate in one embodiment of the present invention; Figure 8 1 is a schematic structural diagram of a stirring shaft and a stirring blade in one embodiment of the present invention; Figure 9 1 is a schematic flow chart of a method for preparing dimethyl ether in one embodiment of the present invention.

[0018] Description of reference numerals: 1. Air carbon dioxide capture device; 11. Gas adsorption module; 12. Heating and desorption module; 121. Heating wire; 122. Temperature control unit; 13. Carbon dioxide collection tank; 2. Hydrogen production device; 21. Cathode; 22. Anode; 23. Proton exchange membrane; 24. Hydrogen collection tank; 25. Power module; 26. Electrolyzer; 3. Slurry bed reactor; 31. Reactor housing; 311. Reaction inlet; 32. Reactor cover; 321. Pressure control valve; 322. Thermometer; 323. Stirring drive; 33. Heating assembly; 34. Gas distribution plate; 341. Stirring blades; 342. Diversion holes; 343. First reinforcement layer; 344. Second reinforcement layer; 35. Stirring shaft; 36. Reaction chamber; 361. Gas mixing zone; 362. Gas-liquid-solid mixing reaction chamber; 37. Gas mixing layer; 371. Honeycomb ceramic structured packing; 372. Hydrophobic silicon carbide coating; 4. Methanol collection device; 41. First condenser; 42. Methanol collection tank; 5. Dimethyl ether collection device; 51. First gas compressor; 52. Second condenser; 53. Dimethyl ether collection tank; 6. Fourier transform infrared spectrometer; 7. Second gas compressor. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] In order to solve the above technical problems, the present invention provides a dimethyl ether preparation system and a preparation method thereof, which can not only reduce energy consumption and carbon emissions, but also improve the preparation efficiency of dimethyl ether.

[0021] Example 1: See also Figure 1 , Figure 1 This is a schematic diagram of the overall structure of a dimethyl ether preparation system provided by the present invention, which includes an air carbon dioxide capture device 1, a hydrogen production device 2, a mixing reactor and a dimethyl ether collection device 5; wherein, the air carbon dioxide capture device 1 can collect carbon dioxide from the air, the hydrogen production device 2 can produce hydrogen required for the reaction, the carbon dioxide and hydrogen are mixed in the mixing reactor and react with the catalyst, and the dimethyl ether collection device 5 can process the gas after the reaction and collect dimethyl ether in the gas, thereby completing the preparation of dimethyl ether.

[0022] See also Figure 1-2 In this embodiment, the above-mentioned air carbon dioxide capture device 1 includes a gas adsorption module 11, a heating and desorption module 12 and a carbon dioxide collection tank 13. The gas adsorption module 11 can adsorb carbon dioxide in the air, and the heating and desorption module 12 heats the gas adsorption module 11, so that carbon dioxide is desorbed from the gas adsorption module 11 and finally collected by the carbon dioxide collection tank 13.

[0023] Specifically, the heating and desorption module 12 includes a heating base, within which a heating wire 121 may be disposed. To facilitate control of the heating temperature, a temperature control unit 122 may also be provided on the heating base. The temperature control unit 122 includes a temperature sensor and a corresponding control module. The control module is electrically connected to the heating wire 121 to control the power of the heating wire 121. The temperature control unit 122 enables real-time monitoring of the temperature within the heating base, facilitating control of the heating temperature of the heating wire 121. For example, in one embodiment, the heating temperature of the heating wire 121 can be controlled between 80°C and 120°C.

[0024] It is understandable that the specific structural composition of the temperature control unit 122 belongs to the prior art and is not the focus of the present invention, so it will not be described in detail here.

[0025] The gas adsorption module 11 is disposed as a whole on the upper side of the heating base. It can be made of a material with carbon dioxide adsorption function. The specific material used can be determined based on the adsorption capacity of different materials. For example, in one embodiment, the gas adsorption module 11 can be a Mg-MOFs-74 porous solid; in this case, the adsorption capacity of the gas adsorption module 11 can reach 0.08 mmol·g-1. Of course, the gas adsorption module 11 can also be made of other adsorption materials, provided that the carbon dioxide adsorption capacity requirements are met, and this is not specifically limited.

[0026] The above-mentioned carbon dioxide collection tank 13 can adopt any tank body with gas collection function, and the gas inlet on it is connected to the gas outlet on the heating base through a pipeline, and the gas outlet of the carbon dioxide collection tank 13 can be connected to the gas inlet of the mixing reactor through a pipeline.

[0027] See also Figure 3 In this embodiment, the above-mentioned hydrogen production device 2 can be a water electrolysis hydrogen production device, which produces hydrogen by electrolyzing water, which is clean and pollution-free and convenient for using green electricity.

[0028] Specifically, the hydrogen production device 2 includes an electrolytic cell 26, an electrolytic unit, a power module 25, and a hydrogen collection tank 24 connected to the electrolytic cell 26. The electrolytic cell 26 can be configured as a square tank structure or other structural forms, which is not specifically limited. The electrolytic unit includes a cathode 21 and an anode 22 fixedly arranged inside the electrolytic cell 26. The cathode 21 and the anode 22 can be respectively arranged on opposite sides of the electrolytic cell 26, and the surfaces of the cathode 21 and the anode 22 are both coated with a catalyst, which can be a Co3O4 catalyst or other similar catalyst. At the same time, a proton exchange membrane 23 is also provided between the cathode 21 and the anode 22, and the proton exchange membrane 23 can be fixed to the inside of the electrolytic cell 26 by a bracket. The power module 25 can adopt a DC power supply powered by solar green electricity, which can be connected to the cathode 21 and the anode 22 respectively by wires, thereby driving the hydrolysis reaction by DC voltage to achieve hydrogen production.

[0029] The above-mentioned hydrogen collection tank 24 can be any tank with a gas collection function, and the gas inlet thereon can be connected to the gas outlet of the electrolyzer 26 through a pipeline, and the gas outlet of the hydrogen collection tank 24 can be connected to the gas inlet of the mixing reactor through a pipeline.

[0030] See also Figure 4-5 The above-mentioned mixing reactor is mainly used to mix the carbon dioxide from the carbon dioxide collection tank 13 and the hydrogen from the hydrogen collection tank 24, and make them react with the catalyst in the mixing reactor.

[0031] In this embodiment, the mixing reactor can be a slurry bed reactor 3, which includes a reactor shell 31 and a reactor cover 32. The reactor shell 31 can be configured as a structure with a hollow interior and an open top. The reactor cover 32 is installed on the top of the reactor shell 31 and is preferably configured as a detachable structure on the reactor shell 31. A reaction inlet 311 for carbon dioxide and hydrogen is provided at the bottom of the reactor shell 31, and the interior space of the reactor shell 31 constitutes a reaction chamber 36. The reaction chamber 36 not only provides a mixing space for carbon dioxide and hydrogen, but also provides a space for the mixed gas to undergo a catalytic reaction with the catalyst.

[0032] To further enhance the reaction efficiency, the reaction chamber 36 can be divided into multiple distinct compartments as needed to accommodate gas mixing, catalytic reactions, or other requirements. For example, in one embodiment, the reaction chamber 36 includes, from bottom to top, a gas-phase mixing zone 361 and a gas-liquid-solid mixing reaction chamber 362. The gas-phase mixing zone 361 is primarily used for mixing carbon dioxide and hydrogen, while the gas-liquid-solid mixing reaction chamber 362 provides the space required for the reaction between the mixed gas and the catalyst.

[0033] Specifically, the gas phase mixing zone 361 can be set at the bottom of the reaction chamber 36, and the gas inlet of the slurry bed reactor 3 can also be set at the bottom of the reactor shell 31; in this way, when the gas (carbon dioxide and hydrogen) enters the reaction chamber 36 through the gas inlet on the slurry bed reactor 3, the gas needs to pass through the gas phase mixing zone 361 before entering the gas-liquid-solid mixing reaction chamber 362.

[0034] See also Figure 5-6 In order to improve the gas mixing effect, a gas mixing layer 37 is further provided in the gas phase mixing zone 361 for mixing the reaction gas; the gas mixing layer 37 can be provided in a structural form in which multiple layers of materials are compositely stacked in sequence from bottom to top. For example, in one embodiment, the gas mixing layer 37 includes a honeycomb ceramic structured filler 371 provided at the bottom of the gas phase mixing zone 361 and a hydrophobic silicon carbide coating 372 uniformly coated on the surface of the honeycomb ceramic structured filler 371; wherein, the honeycomb ceramic structured filler 371 can uniformly mix the carbon dioxide and hydrogen entering the gas phase mixing zone 361, and when the mixed gas passes through the hydrophobic silicon carbide coating 372, the hydrophobic silicon carbide coating 372 can remove moisture in the mixed gas.

[0035] The gas-liquid-solid mixing reaction chamber 362 is located above the gas-phase mixing zone 361 and contains a solid catalyst, which can be a composite catalyst of gallium nitride and CaCO3. Paraffin, an inert liquid, is also contained within the gas-liquid-solid mixing reaction chamber 362. This inert liquid provides a stable reaction environment for the reaction between the mixed gas and the catalyst, ensuring a smooth reaction and helping to improve the purity of the final product.

[0036] See also Figure 5 and Figure 7 A gas distribution plate 34 is also provided between the above-mentioned gas phase mixing zone 361 and the gas-liquid-solid mixing reaction chamber 362. The gas distribution plate 34 can not only separate the gas phase mixing zone 361 and the gas-liquid-solid mixing reaction chamber 362, but also can evenly divert the mixed gas, so that the mixed gas can fully contact the catalyst and fully react with it.

[0037] Specifically, the gas distribution plate 34 can be made of stainless steel and provided with a plurality of evenly distributed guide holes 342. The function of the guide holes 342 is to allow the mixed gas to pass through. The aperture size can be set as needed. However, considering the presence of liquid in the gas-liquid-solid mixing reaction chamber 362 above, the aperture of the guide holes 342 should not be too large. For example, in one embodiment, the aperture of the guide holes 342 can be set to 2μm.

[0038] In actual operation, carbon dioxide and hydrogen are mixed in the gas phase mixing zone 361. Under the pressure from the carbon dioxide collection tank 13 and the hydrogen collection tank 24, the mixed gas moves upward and passes through the guide hole 342 into the gas-liquid-solid mixing reaction chamber 362 above. During this process, due to the obstruction of the gas distribution plate 34, the mixed gas will be evenly dispersed along the plate surface of the gas distribution plate 34 and eventually enter the gas-liquid-solid mixing reaction chamber 362 through the guide hole 342, thereby achieving a uniform gas flow diversion effect. When the gas enters the gas-liquid-solid mixing reaction chamber 362, the mixed gas will react with the catalyst in the form of bubbles.

[0039] Considering that the gas distribution plate 34 is subject to pressure from both above and below, a reinforcement layer can be provided on the gas distribution plate 34. For example, in one embodiment, a first reinforcement layer 343 and a second reinforcement layer 344 are sequentially provided on one side of the gas distribution plate 34. The first reinforcement layer 343 can be made of stainless steel, with a hollow support structure in cross-section and a surface gap for gas to pass through. The second reinforcement layer 344 can also be made of stainless steel and have multiple air holes. The aperture of each air hole can be larger than the aperture of the guide holes 342 on the gas distribution plate 34. The first and second reinforcement layers 343 and 344 can enhance the structural strength of the gas distribution plate 34 and reduce the probability of deformation of the gas distribution plate 34.

[0040] It should be understood that the above-mentioned first reinforcement layer 343 and second reinforcement layer 344 are arranged on the same side of the gas distribution plate 34. Under the premise of not affecting the passage of gas, the first reinforcement layer 343 and the second reinforcement layer 344 can also be respectively arranged on both sides of the gas distribution plate 34, and the upper and lower relationship between the two can also be adjusted as needed, and the material of the first reinforcement layer 343 and the second reinforcement layer 344 can also be other materials that are not easy to rust, and there is no specific limitation on this.

[0041] See also Figure 5 and Figure 8 In order to further achieve sufficient reaction between the mixed gas and the catalyst, a stirring blade 341 is fixedly provided on the plate surface of the gas distribution plate 34 .

[0042] Correspondingly, the reactor housing 31 is also provided with a stirring shaft 35 and a stirring drive 323. The stirring shaft 35 is rotatably mounted on the reactor cover 32 via a bearing, and its ends are respectively connected to the gas distribution plate 34 and the stirring drive 323. The stirring drive 323 can be an asynchronous motor or other type of motor. For example, the asynchronous motor can be fixed to the reactor cover 32 via bolts, and the output shaft of the asynchronous motor can be connected to the stirring shaft 35 via a coupling.

[0043] During operation, the asynchronous motor can drive the stirring shaft 35 and the gas distribution plate 34 to rotate. With the help of the stirring blades 341 set on the gas distribution plate 34, the gas and the catalyst can be stirred, so that the gas can fully contact and react with the catalyst.

[0044] See also Figure 4-5 In order to further accelerate the reaction speed, a heating component 33 can be provided on the reactor housing 31. The heating component 33 can be an electric heating wire evenly distributed around the reaction chamber 36. By controlling the power of the electric heating wire, the internal temperature of the reaction chamber 36 can be controlled within a suitable temperature range to meet the temperature requirements of the reaction.

[0045] To precisely control the internal temperature of reaction chamber 36, a temperature control unit may be provided on reactor housing 31. The configuration of this temperature control unit may be similar to that of temperature control unit 122 described above and will not be further described here. Furthermore, to facilitate operators in understanding the internal temperature of reaction chamber 36, a thermometer 322 may be provided on reactor housing 31, allowing operators to visually view the temperature display.

[0046] In order to further achieve sufficient reaction, a pressure control valve 321 and a pressure detection gauge can be further provided on the reactor shell 31. Through the cooperation of the pressure control valve 321 and the pressure detection gauge, the internal pressure of the reaction chamber 36 can be controlled under relatively high conditions. For example, the internal pressure of the reaction chamber 36 can be controlled at 2 MPa or other pressure values. The higher pressure condition can effectively prevent gas diffusion and make the gas contact with the catalyst more complete.

[0047] See also Figure 1 A methanol collecting device 4 is also provided between the above-mentioned dimethyl ether collecting device 5 and the slurry bed reactor 3. The methanol collecting device 4 includes a first condenser 41. The gas inlet of the first condenser 41 can be connected to the gas outlet of the slurry bed reactor 3 through a pipeline, and the gas outlet of the first condenser 41 is also connected to a methanol collecting tank 42 through a pipeline.

[0048] After the reaction is complete within the slurry bed reactor 3, the reacted gas passes through the first condenser 41 and the methanol collection tank 42 via a pipeline. During this process, the first condenser 41 condenses the reacted gas, liquefying the methanol in the gas as it passes through the methanol collection tank 42 and is stored there. It should be noted that the condensation temperature of the first condenser 41 can be determined based on the characteristics of methanol. For example, in one embodiment, the temperature of the first condenser 41 can be set to 0°C.

[0049] The above-mentioned dimethyl ether collection device 5 includes a first gas compressor 51, the gas inlet of the first gas compressor 51 is connected to the gas outlet of the methanol collection tank 42 through a pipeline, and its gas outlet is connected to the second condenser 52 through a pipeline, and the gas outlet of the second condenser 52 is further connected to the dimethyl ether collection tank 53 through a pipeline.

[0050] After the methanol in the gas is liquefied and stored in the methanol collecting tank 42, the gas enters the first gas compressor 51, which can pressurize the gas. The pressurized gas is then condensed through the second condenser 52 and enters the dimethyl ether collecting tank 53; in the dimethyl ether collecting tank 53, the dimethyl ether in the gas will be liquefied and stored in the dimethyl ether collecting tank 53, and the remaining gas will be discharged through the gas outlet on the dimethyl ether collecting tank 53.

[0051] It should be understood that the pressure of the first gas compressor 51 and the temperature of the second condenser 52 can be flexibly set as needed. For example, in one embodiment, the pressure of the first gas compressor 51 can be set to 0.8 MPa, and the temperature of the second condenser 52 can be set to 0°C. As long as dimethyl ether can be liquefied in the dimethyl ether collection tank 53, the pressure of the first gas compressor 51 and the temperature of the second condenser 52 are not specifically limited.

[0052] In another embodiment, in order to further determine the content of the product in the dimethyl ether collecting tank 53, the dimethyl ether collecting tank 53 is further connected to a Fourier infrared spectrometer 6 to detect the composition of the product in the dimethyl ether collecting tank 53 to facilitate the determination of the dimethyl ether content.

[0053] In another embodiment, considering that the gas discharged from the dimethyl ether collection tank 53 may also contain a large amount of carbon dioxide and hydrogen, in order to further utilize this gas, the gas outlet of the dimethyl ether collection tank 53 is also connected to a second gas compressor 7 via a pipeline. The gas outlet of the second gas compressor 7 is connected to the gas inlet of the above-mentioned slurry bed reactor 3 via a pipeline, and the pressure value of the second gas compressor 7 can be consistent with the pressure of the above-mentioned carbon dioxide collection tank 13 and hydrogen collection tank 24. For example, the pressure of all three can be controlled at 2 MPa. In this way, after the gas is discharged from the dimethyl ether collection tank 53, the second gas compressor 7 can pressurize the discharged gas so that its pressure is consistent with the pressure of the carbon dioxide from the carbon dioxide collection tank 13 and the hydrogen from the hydrogen collection tank 24.

[0054] In this way, the reacted gas can enter the slurry bed reactor 3 together with the initially collected carbon dioxide and hydrogen and participate in the reaction together, thereby realizing recycling, thereby improving the utilization rate of carbon dioxide and hydrogen and reducing loss.

[0055] It is understood that the electricity used by the dimethyl ether preparation system provided in this embodiment can all be provided by solar green electricity. For example, the electricity required to operate components such as the heating and desorption module 12, the electrolysis unit, the heating device on the reactor housing 31, and the stirring drive 323 on the reactor housing 31 can all be provided by solar green electricity. In this way, the utilization rate of solar green electricity can be improved, gas emissions can be reduced, and efficient use of clean energy can be achieved.

[0056] Example 2: See also Figure 9 , Figure 9 The present invention provides a process flow diagram of a method for preparing dimethyl ether, which comprises the following steps: S1. Collect carbon dioxide and produce hydrogen required for the reaction.

[0057] In actual operation, carbon dioxide is collected by the air carbon dioxide capture device 1. The air carbon dioxide capture device 1 can adsorb carbon dioxide from the air through the gas adsorption module 11 and heat the gas adsorption module 11 using the heating and desorption module 12, so that the carbon dioxide is desorbed from the gas adsorption module 11 and enters the carbon dioxide collection tank 13 through a pipeline to complete the collection of carbon dioxide.

[0058] Hydrogen can be produced by electrolysis of water. Specifically, with the aforementioned hydrogen production device 2, the power module 25 uses solar energy to provide a DC voltage between the cathode 21 and anode 22. This, combined with the catalysts on the cathode 21 and anode 22, drives the hydrolysis reaction to produce the hydrogen required for dimethyl ether. The produced hydrogen is ultimately piped into a hydrogen collection tank 24 for storage and backup.

[0059] S2. Pass carbon dioxide and hydrogen into the slurry bed reactor 3, so that the mixed gas reacts with the catalyst in the slurry bed reactor 3.

[0060] After the carbon dioxide and hydrogen are collected, they enter reaction chamber 36 through the gas inlet of slurry bed reactor 3. In reaction chamber 36, the carbon dioxide and hydrogen first enter gas-phase mixing zone 361. Within gas-phase mixing zone 361, they are fully mixed by gas mixing layer 37 and ultimately enter gas-liquid-solid mixing reaction chamber 362 above through gas distribution plate 34. During this process, gas distribution plate 34 evenly distributes the mixed gas.

[0061] In the gas-liquid-solid mixing reaction chamber 362 , the stirring drive 323 drives the stirring shaft 35 and the stirring blade 341 to rotate and stir the mixed gas and the catalyst, so that the mixed gas and the catalyst are fully in contact and fully react in the paraffin inert liquid.

[0062] During the reaction, the heating wire and pressure control valve 321 provided on the reactor housing 31 can precisely control the temperature and pressure within the reaction chamber 36 to ensure a sufficient reaction. The temperature within the reaction chamber 36 can be controlled at approximately 360°C, and the pressure within the reaction chamber 36 can be controlled at 2 MPa.

[0063] S3. Condensing the gas after the reaction once to obtain liquefied methanol.

[0064] After the reaction is complete within the slurry bed reactor 3, the reacted gas passes through the first condenser 41 and the methanol collection tank 42 via a pipeline. During this process, the first condenser 41 condenses the reacted gas, liquefying the methanol in the gas as it passes through the methanol collection tank 42 and is stored there. It should be noted that the condensation temperature of the first condenser 41 can be determined based on the characteristics of methanol. For example, in one embodiment, the temperature of the first condenser 41 can be set to 0°C.

[0065] S4. Pressurizing the gas after the reaction and performing secondary condensation to obtain liquefied dimethyl ether.

[0066] After the methanol in the gas is liquefied and stored in the methanol collecting tank 42, the gas enters the first gas compressor 51, which can pressurize the gas. The pressurized gas is then condensed through the second condenser 52 and enters the dimethyl ether collecting tank 53; in the dimethyl ether collecting tank 53, the dimethyl ether in the gas will be liquefied and stored in the dimethyl ether collecting tank 53, and the remaining gas will be discharged through the gas outlet on the dimethyl ether collecting tank 53.

[0067] It should be understood that the pressure of the first gas compressor 51 and the temperature of the second condenser 52 can be flexibly set as needed. For example, in one embodiment, the pressure of the first gas compressor 51 can be set to 0.8 MPa, and the temperature of the second condenser 52 can be set to 0°C. As long as dimethyl ether can be liquefied in the dimethyl ether collection tank 53, the pressure of the first gas compressor 51 and the temperature of the second condenser 52 are not specifically limited.

[0068] Considering that the gas discharged from the dimethyl ether collecting tank 53 may still contain a large amount of carbon dioxide and hydrogen, after the gas is discharged from the dimethyl ether collecting tank 53, the second gas compressor 7 can pressurize the discharged gas so that its pressure is consistent with the pressure of the carbon dioxide from the carbon dioxide collecting tank 13 and the hydrogen from the hydrogen collecting tank 24, and further pass this part of the gas into the gas inlet on the slurry bed reactor 3, so that the reacted gas and the initially collected carbon dioxide and hydrogen enter the slurry bed reactor 3 at the same time and participate in the reaction together, realizing recycling, thereby improving the utilization rate of carbon dioxide and hydrogen and reducing loss.

[0069] See also Figure 1-8 In this embodiment, carbon dioxide and hydrogen are mixed and reacted with a catalyst (a composite catalyst of GaN and CaCO3) under heating and pressurizing conditions within reaction chamber 36 to produce dimethyl ether. The dimethyl ether is discharged from reaction chamber 36 along with the gas and eventually liquefied by condensation and stored in a dimethyl ether collection tank 53.

[0070] Experiments have shown that CO2 conversion improves with decreasing GaN crystal size, regardless of the H2 / CO2 ratio. Furthermore, when hydrogenation products are detected using a flame ionization detector (FID), dimethyl ether (DME) is the primary product, with larger GaN crystals favoring DME formation. Decreased DME selectivity is always accompanied by increased methanol selectivity. The increased activity with decreasing GaN size is primarily due to enhanced RWGS (reverse water-gas shift) reactions, with the highest DME yield achieved when the GaN crystal size is 26.6 nm.

[0071] Therefore, the gallium nitride in this embodiment is a pure tungsten structure with a crystal size of 26.6 nm and a crystal orientation of (110) plane. The molar ratio of the CaCO3 alkaline promoter to the gallium nitride is 1. This mixed catalyst has the highest dimethyl ether yield when participating in the reaction, which can reach 2.9 mmol g -1 h -1 .

[0072] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise expressly specified and limited, the terms "installed", "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 internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0073] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0074] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A dimethyl ether preparation system, characterized in that: include: Air carbon dioxide capture device, used to collect carbon dioxide from the air; A hydrogen production device for producing hydrogen; A mixing reactor connected to the air carbon dioxide capture device and the hydrogen production device for mixed catalytic reaction; as well as The dimethyl ether collecting device is connected to the mixing reactor and is used to collect dimethyl ether in the reaction gas.

2. The dimethyl ether preparation system according to claim 1, characterized in that: The air carbon dioxide capture device comprises: Gas adsorption module, used to adsorb carbon dioxide from the air; a heating and desorption module, connected to the gas adsorption module and used to heat the gas adsorption module; and The carbon dioxide collection tank is connected to the heating desorption module and the mixing reactor, and is used to collect the desorbed carbon dioxide and supply carbon dioxide to the mixing reactor.

3. The dimethyl ether preparation system according to claim 1, characterized in that: The hydrogen production device comprises: electrolytic cell; an electrolysis unit, disposed in the electrolytic cell, for electrolyzing water to produce hydrogen; and A hydrogen collecting tank is connected to the gas outlets of the mixing reactor and the electrolyzer, and is used to collect hydrogen and supply hydrogen to the mixing reactor.

4. The dimethyl ether preparation system according to claim 1, characterized in that: The mixing reactor is a slurry bed reactor, and the slurry bed reactor comprises: Reactor housing; A reaction chamber is located inside the reactor shell, and a catalyst is arranged in the reaction chamber; a heating device, disposed on the reactor housing, for heating the reaction chamber; and A pressure control valve is provided on the reactor shell and communicated with the reaction chamber, and is used for controlling the pressure inside the reaction chamber.

5. The dimethyl ether preparation system according to claim 4, characterized in that: The reaction chamber includes: a gas phase mixing zone, located at the bottom of the reaction chamber, wherein a gas mixing layer is provided in the gas phase mixing zone for mixing reaction gases; and The gas-liquid-solid mixing reaction chamber is located above the gas phase mixing zone, and the catalyst is located in the gas-liquid-solid mixing reaction chamber for mixing and reacting with the reaction gas.

6. The dimethyl ether preparation system according to claim 5, characterized in that: A gas distribution plate is further provided in the reaction chamber. The gas distribution plate is located between the gas phase mixing zone and the gas-liquid-solid mixing reaction chamber, and a plurality of evenly distributed guide holes are provided on the gas distribution plate.

7. The dimethyl ether preparation system according to claim 6, characterized in that: The gas distribution plate is also fixedly provided with a stirring blade; the reactor shell is provided with a stirring shaft and a stirring driving member, and the two ends of the stirring shaft are respectively connected to the gas distribution plate and the stirring driving member.

8. The dimethyl ether preparation system according to claim 1, characterized in that: A methanol collecting device is further provided between the mixed reaction formula and the dimethyl ether collecting device, and the methanol collecting device comprises: a first condenser connected to the mixing reactor via a pipeline, and configured to condense the gas after the reaction and liquefy the methanol; and A methanol collecting tank is connected to the outlet of the first condenser through a pipeline and is used to collect liquefied methanol.

9. The dimethyl ether preparation system according to claim 8, characterized in that: The dimethyl ether collection device comprises: a first gas compressor, the first gas compressor being connected to the gas outlet of the methanol collection tank via a pipeline for achieving gas pressurization; a second condenser connected to the first gas compressor via a pipeline, for condensing gas and liquefying dimethyl ether; and A dimethyl ether collecting tank is connected to the gas outlet of the second condenser through a pipeline and is used to collect liquefied dimethyl ether.

10. A method for preparing dimethyl ether, using the dimethyl ether preparation system according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, collect carbon dioxide and prepare hydrogen required for the reaction; S2, introducing carbon dioxide and hydrogen into a slurry bed reactor, so that the mixed gas reacts with the catalyst in the slurry bed reactor; S3, condensing the gas after the reaction to obtain liquefied methanol; S4. Pressurizing the gas after the reaction and performing secondary condensation to obtain liquefied dimethyl ether.

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