A system and method for catalytic reduction hydrogenation of carbon dioxide in a hollow tube

Abstract

The present disclosure relates to a system and method for catalytic reduction hydrogenation of carbon dioxide, which forms a feed chamber and a discharge chamber between a temperature regulating layer and a shell, and only communicates the feed chamber and the discharge chamber through a plurality of hollow tubular catalyst-coated optical fibers with photocatalysts attached to the inner walls, so that the hydrogenation reaction material is buffered in the feed chamber and then enters the plurality of catalyst-coated optical fibers to contact the catalyst for hydrogenation reaction. This can increase the specific surface area of the catalyst and the residence time of the hydrogenation reaction material in the photocatalyst reactor, thereby improving the hydrogenation reaction effect of carbon dioxide. In addition, by adjusting the flow direction of the separated gas phase according to the concentration of carbon dioxide in the gas phase, the conversion rate of carbon dioxide can be improved.

Description

Technical Field

[0001] This disclosure relates to the field of carbon dioxide capture, and more specifically, to a system and method for a hollow tube-type catalytic reduction hydrogenation reaction of carbon dioxide. Background Technology

[0002] In existing technologies, photocatalytic reduction is commonly used to effectively utilize carbon dioxide. This method converts captured carbon dioxide and hydrogen produced by electrolysis of water powered by renewable energy sources (solar, wind, biomass, etc.) into energy compounds under the catalysis of a photocatalyst. However, the photocatalytic reaction systems used in existing technologies have drawbacks such as a single reaction pathway, low light utilization, small total surface area of ​​the catalyst and hydrogenation reactants, and inflexible reaction conditions, which in turn affect the efficiency and quality of the photocatalytic reaction. Summary of the Invention

[0003] The purpose of this disclosure is to provide a system and method for a hollow tube-type carbon dioxide catalytic reduction hydrogenation reaction to solve the problems of single reaction pathway, low light utilization, small catalyst specific surface area, and inflexible reaction conditions in the prior art.

[0004] To achieve the above objectives, the first aspect of this disclosure provides a hollow tube-type carbon dioxide catalytic reduction hydrogenation reaction system, comprising a gas mixer, a photocatalytic reactor, a blower, a liquid collector, and a gas collector; the photocatalytic reactor comprises a shell with an overall cylindrical structure, a temperature regulating layer, a diffuse reflection layer, a catalyst-coated fiber optic assembly, and a tunable wavelength light source; the shell contains, from top to bottom, a feed chamber, a reaction chamber, and a discharge chamber; the temperature regulating layer covers the outside of the reaction chamber; the diffuse reflection layer, the catalyst-coated fiber optic assembly, and the tunable wavelength light source are arranged sequentially from the outside to the inside of the reaction chamber; the catalyst-coated fiber optic assembly comprises multiple catalyst-coated fibers, wherein the catalyst-coated fibers are... A hollow tube with photocatalyst attached to its inner wall; one end of the hollow tube extends to the feed chamber to form a material inlet, and the other end extends to the discharge chamber to form a material outlet; the feed chamber and the discharge chamber are respectively provided with a feed port and a discharge port; the feed port is connected to the outlet of the gas mixer, and the discharge port is connected to the inlet of the blower; the inlet of the liquid collector is connected to the outlet of the blower; the gas phase outlet pipeline of the liquid collector is divided into a circulating gas phase pipeline and a gas phase collection pipeline; the gas phase outlet of the liquid collector is connected to the feed port of the photocatalytic reactor through the circulating gas phase pipeline; the gas phase outlet of the liquid collector is connected to the inlet of the gas collector through the gas phase collection pipeline.

[0005] Optionally, the diffuse reflection layer is disposed on the inner wall of the temperature regulating layer; the tunable wavelength light source is disposed axially inside the reaction chamber, preferably coaxially with the reaction chamber; the tunable wavelength light source is coaxially with the housing.

[0006] Optionally, the catalyst-coated optical fiber is arranged axially inside the reaction chamber; the sidewall of the catalyst-coated optical fiber is provided with a plurality of reflective grooves; the ratio of the width of the reflective groove to the length of the catalyst-coated optical fiber is (0.05~0.2):1.

[0007] Optionally, a plurality of catalyst-coated optical fibers are arranged in parallel, and the plurality of catalyst-coated optical fibers are arranged at intervals along the same circumference on a plane perpendicular to the axial direction; the ratio of the length of the catalyst-coated optical fiber to the height of the housing is (0.6~0.8):1; the inner diameter of the catalyst-coated optical fiber is 1~10mm.

[0008] Optionally, the tunable wavelength light source includes one or more of the following: xenon lamp light source, QTH tunable quartz halogen lamp light source, deuterium lamp light source, and halogen tungsten lamp light source.

[0009] Optionally, the system further includes a control unit and a carbon dioxide concentration detector disposed at the feed inlet of the photocatalytic reactor; the control unit is electrically connected to the carbon dioxide concentration detector, the tunable wavelength light source and the temperature regulation layer respectively, and is used to receive the concentration signal from the carbon dioxide concentration detector and adjust the input power of the tunable wavelength light source and / or the temperature regulation layer according to the concentration signal.

[0010] The second aspect of this disclosure involves a method for performing a carbon dioxide catalytic reduction hydrogenation reaction using the system described in the first aspect. The method includes: mixing carbon dioxide and hydrogen in a gas mixer to obtain a hydrogenation reactant; introducing the hydrogenation reactant into a catalyst-coated optical fiber assembly in a photocatalytic reactor to contact the photocatalyst for hydrogenation reaction, obtaining a hydrogenation reaction product; allowing the hydrogenation reaction product to enter a liquid collector under the action of a fan for gas-liquid separation, obtaining a liquid phase product and a separated gas phase; when the carbon dioxide concentration in the separated gas phase is less than a collection threshold, allowing the separated gas phase to enter the gas collector; when the carbon dioxide concentration in the separated gas phase is greater than the collection threshold, returning the separated gas phase to the photocatalytic reactor to continue the reaction until the carbon dioxide content in the separated gas phase is less than the collection threshold, at which point the separated gas phase enters the gas collector; the collection threshold is 10-30% by volume.

[0011] Optionally, the conditions for the hydrogenation reaction include: a reaction temperature of 50-100°C, a reactant residence time of 5-10 seconds, and a light irradiance of 20-200 W / m² from a tunable wavelength light source. 2 .

[0012] Optionally, the photocatalyst comprises one or more of titanium dioxide particles, zinc oxide particles, and tin oxide particles.

[0013] Through the above technical solution, a feed chamber is formed between the temperature regulating layer and the top of the shell, and a discharge chamber is formed between the temperature regulating layer and the bottom of the shell. The feed chamber and discharge chamber are connected only by multiple hollow tubular catalyst-coated optical fibers with photocatalysts attached to their inner walls. This allows the hydrogenation reactants to enter the multiple catalyst-coated optical fibers after being buffered in the feed chamber, where they contact the catalyst for hydrogenation. This increases the total surface area of ​​contact between the hydrogenation reactants and the catalyst, while also increasing the residence time of the hydrogenation reactants in the photocatalytic reactor, thereby improving the hydrogenation effect of carbon dioxide. Furthermore, the diffuse reflection layer in the photocatalytic reactor allows light to be continuously reflected within a relatively small enclosed space, significantly improving light utilization and consequently increasing the efficiency and effect of the photocatalytic reaction. Additionally, by flexibly adjusting the flow of the separated gas phase to the gas collector or photocatalytic reactor according to the concentration of carbon dioxide in the separated gas phase, the conversion rate of carbon dioxide can be improved.

[0014] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of a cross-section of a photocatalytic reactor disclosed herein.

[0016] Figure 2 This is a top view of a photocatalytic reactor disclosed herein.

[0017] Figure 3 This is a schematic diagram of a catalyst-coated optical fiber used in a photocatalytic reactor disclosed herein.

[0018] Figure 4 This is a schematic diagram of a hollow tube-type carbon dioxide catalytic reduction hydrogenation system disclosed herein.

[0019] Figure 5 This is a schematic diagram of the photocatalytic reactor used in Comparative Example 1 of this disclosure.

[0020] Explanation of reference numerals in the attached figures 1 Gas mixer; 2 Photocatalytic reactor; 3 Fan; 4 Liquid collector; 5 Gas collector; 6 First valve; 7 Second valve; 8 Third valve; 9 Control unit; 20 Housing; 21 Temperature regulating layer; 22 Diffuse reflection layer; 23 Catalyst-coated optical fiber; 24 Tunable wavelength light source; 25 Feed chamber; 26 Discharge chamber; 28 Reflective groove; 29 Heating layer; 30 Reflective layer; 31 Reaction tube; 32 Light source. Detailed Implementation

[0021] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0022] In this disclosure, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its normal operating state, for example, as shown in the reference. Figure 1 In the drawing orientation, "inner" and "outer" refer to those relative to the outline of the device. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] like Figure 1 and Figure 4As shown, the first aspect of this disclosure provides a hollow tube-type carbon dioxide catalytic reduction hydrogenation reaction system, which includes a gas mixer 1, a photocatalytic reactor 2, a blower 3, a liquid collector 4, and a gas collector 5; the photocatalytic reactor 2 includes a shell 20 with an overall cylindrical structure, a temperature regulating layer 21, a diffuse reflection layer 22, a catalyst-coated optical fiber assembly, and a tunable wavelength light source 24; the shell 20 has a feed chamber 25, a reaction chamber, and a discharge chamber 26 arranged sequentially from top to bottom; the temperature regulating layer 21 covers the outside of the reaction chamber; the diffuse reflection layer 22, the catalyst-coated optical fiber assembly, and the tunable wavelength light source 24 are arranged sequentially from the outside to the inside of the reaction chamber; the catalyst-coated optical fiber assembly includes a plurality of catalyst-coated optical fibers 23, and the catalyst-coated optical fiber assembly... Fiber 23 is a hollow tube with photocatalyst attached to its inner wall; one end of the hollow tube extends to the feed chamber 25 to form a material inlet, and the other end extends to the discharge chamber 26 to form a material outlet; the feed chamber 25 and the discharge chamber 26 are respectively provided with a feed inlet and a discharge outlet; the feed inlet is connected to the outlet of the gas mixer 1, and the discharge outlet is connected to the inlet of the blower 3; the inlet of the liquid collector 4 is connected to the outlet of the blower 3; the gas phase outlet pipeline of the liquid collector 4 is divided into a circulating gas phase pipeline and a gas phase collection pipeline; the gas phase outlet of the liquid collector 4 is connected to the feed inlet of the photocatalytic reactor 2 through the circulating gas phase pipeline; the gas phase outlet of the liquid collector 4 is connected to the inlet of the gas collector 5 through the gas phase collection pipeline.

[0024] Through the above technical solution, a feed chamber is formed between the temperature regulating layer and the top of the shell, and a discharge chamber is formed between the temperature regulating layer and the bottom of the shell. The feed chamber and discharge chamber are connected only by multiple hollow tubular catalyst-coated optical fibers with photocatalysts attached to their inner walls. This allows the hydrogenation reactants to enter the multiple catalyst-coated optical fibers after being buffered in the feed chamber, where they contact the catalyst for hydrogenation. This increases the total surface area of ​​contact between the hydrogenation reactants and the catalyst, while also increasing the residence time of the hydrogenation reactants in the photocatalytic reactor, thereby improving the hydrogenation effect of carbon dioxide. Furthermore, the diffuse reflection layer in the photocatalytic reactor allows light to be continuously reflected within a relatively small enclosed space, significantly improving light utilization and consequently increasing the efficiency and effect of the photocatalytic reaction. Additionally, by flexibly adjusting the flow of the separated gas phase to the gas collector or photocatalytic reactor according to the concentration of carbon dioxide in the separated gas phase, the conversion rate of carbon dioxide can be improved.

[0025] The gas mixer used in this disclosure is a conventional choice in the art, and this application does not make any special requirements. For example, the gas mixer is generally cylindrical, with a hydrogen inlet and a carbon dioxide inlet on the top surface of the cylindrical body, and a mixed raw material gas outlet on the bottom surface of the cylindrical body; and multiple baffles are staggered inside the cylindrical body to make the hydrogen and carbon dioxide mix evenly under the action of the baffles.

[0026] In one embodiment, a first valve 6 is also provided on the outlet pipeline of the gas mixer 1 to control whether the hydrogenation reaction material enters the photocatalytic reactor 2.

[0027] The fan used in this disclosure is a conventional choice in the art, and this application does not make any special requirements, as long as it can transport the hydrogenation reaction products in the photocatalytic reactor to the liquid collector 4.

[0028] The liquid collector 4 and gas collector used in this disclosure are conventional choices in the art, and this application does not make any special requirements. For example, the liquid collector 4 can be selected from a gas-liquid separation tower and / or a gas-liquid separation tank. In this embodiment, the liquid collector 4 includes a hydrogenation reaction product inlet, a liquid phase product outlet, and a separated gas phase outlet. The hydrogenation reaction product inlet of the liquid collector 4 is connected to the outlet of the blower so that the hydrogenation reaction product can enter the liquid collector 4; the liquid phase product outlet of the liquid collector 4 is used to connect to a liquid phase product using device; the separated gas phase outlet of the liquid collector 4 is connected to the inlet of the gas collector so that the separated gas phase can be collected by the gas collector.

[0029] In one embodiment, the gas phase outlet pipeline of the liquid collector 4 is divided into a circulating gas phase pipeline and a gas phase collection pipeline; the gas phase outlet of the liquid collector is connected to the feed inlet of the photocatalytic reactor 2 through the circulating gas phase pipeline; the gas phase outlet of the liquid collector 4 is connected to the inlet of the gas collector 5 through the gas phase collection pipeline.

[0030] In one embodiment, a second valve 7 is provided on the gas phase collection pipeline, and a third valve 8 is provided on the circulating gas phase pipeline to control the return of the separated gas phase to the photocatalytic reactor 2 or into the gas collector 5.

[0031] In one embodiment, the system further includes a control unit 9 for flexibly controlling the operating status of each component.

[0032] In one embodiment, a carbon dioxide concentration detector is further provided at the gas phase product outlet of the liquid collector 4 to detect the carbon dioxide concentration in the separated gas phase. The control unit 9 is electrically connected to the carbon dioxide concentration detector, the first valve 6, the second valve 7, and the third valve 8, respectively, to receive the signal from the carbon dioxide concentration detector and adjust the opening and closing of the first valve 6, the second valve 7, and the third valve 8 according to the signal.

[0033] In this embodiment, the system's operating state can be divided into a first operating state and a second operating state through the adjustment method of the control unit 9. In the first operating state, the control unit keeps the first valve 6 and the second valve 7 open, and the third valve 8 closed, so that the mixture of hydrogen and carbon dioxide sequentially passes through the photocatalytic reactor 2, the fan 3, and the liquid collector 4, resulting in the liquid phase exiting the system and the separated gas phase directly entering the gas collector 5. In the second operating state, the first valve 6 and the second valve 7 are kept closed, and the third valve 8 is kept open, so that the mixture of hydrogen and carbon dioxide circulates sequentially between the photocatalytic reactor 2, the fan 3, and the liquid collector 4.

[0034] like Figure 1 and Figure 2 As shown, the temperature regulating layer 21 in the photocatalytic reactor 2 has an overall cylindrical structure, which is set inside the shell 20. The sidewall of the temperature regulating layer 21 is tightly connected to the inner wall of the shell 20, and the internal cavity of the temperature regulating layer 21 forms a reaction chamber. A gap is left between the top of the temperature regulating layer 21 and the top of the shell 20 to form a feed chamber 25, and a gap is left between the bottom of the temperature regulating layer 21 and the bottom of the shell 20 to form a discharge chamber 26.

[0035] In one embodiment, the temperature regulating device used in the temperature regulating layer 21 is a conventional choice in the art, and this application does not make any requirements. For example, the temperature regulating device used in the temperature regulating layer 21 is an electric heater.

[0036] In one embodiment, the ratio of the height of the temperature regulating layer 21 to the height of the housing 20 is (0.5~0.7):1, preferably (0.55~0.65):1.

[0037] In one embodiment, a diffuse reflection layer 22 is provided inside the reaction chamber and the diffuse reflection layer 22 is placed on the inner wall of the temperature regulating layer 21; the overall structure of the diffuse reflection layer 22 can be conventionally selected in the art, for example, the overall structure of the diffuse reflection layer 22 can be a square cylindrical structure, a circular cylindrical structure or an irregular cylindrical structure, preferably a circular cylindrical structure, and more preferably a circular cylindrical structure without a top surface and a bottom surface.

[0038] The diffuse reflection layer 22 and the inner wall of the temperature regulating layer 21 can be tightly bonded or have a certain gap. Preferably, the diffuse reflection layer 22 and the inner wall of the temperature regulating layer 21 are tightly bonded.

[0039] In one embodiment, the diffuse reflection layer 22 is a reflective grating layer, wherein the reflective grating layer contains 1000-1500 optical slits per millimeter of scribe line. The material of the reflective grating layer includes one or more environmentally friendly materials such as PET, PP, PVC, and TPU.

[0040] In one embodiment, the form of the tunable wavelength light source 24 is conventionally chosen in the art, and this application does not make any special requirements. For example, the light source used in this disclosure is a rod-shaped light source. The tunable wavelength light source 24 is axially disposed inside the reaction chamber. Preferably, the tunable wavelength light source 24 is coaxially disposed with the reaction chamber.

[0041] In one embodiment, the tunable wavelength light source 24 can be selected from the TLS series tunable wavelength light source or the CP-L series wavelength-tunable monochromatic light source; preferably, the tunable wavelength light source 24 includes one or more of xenon lamp sources, QTH tunable quartz halogen lamp sources, deuterium lamp sources, and halogen tungsten lamp sources. In this embodiment, the wavelength of the tunable wavelength light source 24 is 200nm-2500nm.

[0042] In one embodiment, the temperature regulating layer 21 and the tunable wavelength light source 24 are respectively provided with an electrical transmission device, so that the tunable wavelength light source 24 can adjust the light irradiance intensity according to the input power.

[0043] In one embodiment, the catalyst-coated fiber assembly includes a plurality of catalyst-coated fibers 23, which are uniformly disposed in the region between the inner side of the diffuse reflection layer 22 and the outer side of the tunable wavelength light source 24.

[0044] The catalyst-coated optical fiber 23 is parallel to the tunable wavelength light source 24, that is, the catalyst-coated optical fiber 23 is arranged along the axial direction of the housing 20.

[0045] The catalyst-coated optical fibers 23 are arranged in parallel, and are spaced apart along the same circumference on a plane perpendicular to the axial direction. In addition, the catalyst-coated optical fibers 23 penetrate the reaction chamber.

[0046] The ratio of the length of the catalyst-coated optical fiber 23 to the height of the housing 20 is (0.6~0.8):1, preferably (0.65~0.75):1; the inner diameter of the catalyst-coated optical fiber 23 is 1~10mm, preferably 5~10mm, and more preferably 7~8mm.

[0047] In one implementation, such as Figure 3 As shown, to further enhance the photocatalytic reaction effect, multiple reflective grooves 28 are provided on the sidewall of the catalyst-coated optical fiber 23 to increase side light reflection and improve light utilization. The ratio of the width of the reflective groove 28 to the length of the catalyst-coated optical fiber 23 is (0.05~0.2):1, preferably (0.1~0.15):1.

[0048] In this embodiment, the aforementioned reflective grooves 28 create staggered protrusions on the inner wall of the catalyst-coated optical fiber 23, thereby enhancing the contact between the hydrogenation reactants and the catalyst, and thus improving the hydrogenation reaction efficiency. Preferably, the extension directions of the plurality of reflective grooves 28 are at an angle to the axial direction of the catalyst-coated optical fiber 23, so that the protrusions on the inner wall of the catalyst-coated optical fiber 23 form an angle with the axial direction of the catalyst-coated optical fiber 23. This allows the hydrogenation reactants entering the fiber to flow in a spiral pattern, further increasing the residence time of the reactants inside the catalyst-coated optical fiber 23, thereby improving the hydrogenation reaction efficiency.

[0049] In one embodiment, a carbon dioxide concentration detector is provided at the feed inlet of the photocatalytic reactor 2 to detect the concentration of carbon dioxide in the material entering the photocatalytic reactor 2; the control unit 9 is electrically connected to the carbon dioxide concentration detector, the tunable wavelength light source 24 and the temperature regulating layer 21, and is used to receive the carbon dioxide concentration signal from the carbon dioxide concentration detector and adjust the input power of the tunable wavelength light source 24 and / or the temperature regulating layer 21 according to the concentration signal.

[0050] The second aspect of this disclosure involves a method for performing a carbon dioxide catalytic reduction hydrogenation reaction using the system described in the first aspect. The method includes: mixing carbon dioxide and hydrogen in a gas mixer 1 to obtain a hydrogenation reaction material; introducing the hydrogenation reaction material into a photocatalytic reactor 2 where it contacts a photocatalyst to undergo a hydrogenation reaction, yielding a hydrogenation reaction product; allowing the hydrogenation reaction product to undergo gas-liquid separation in a liquid collector 4 under the action of a fan 3, obtaining a liquid phase product and a separated gas phase; when the carbon dioxide concentration in the separated gas phase is less than a collection threshold, allowing the separated gas phase to enter the gas collector 5; when the carbon dioxide concentration in the separated gas phase is greater than the collection threshold, returning the separated gas phase to the photocatalytic reactor 2 to continue the reaction until the carbon dioxide content in the separated gas phase is less than the collection threshold, at which point the separated gas phase enters the gas collector 5; the collection threshold is 10-30% by volume, preferably 15-25% by volume, more preferably 15-20% by volume.

[0051] Through the above technical solution, the hydrogenation reaction material is subjected to hydrogenation reaction in photocatalytic reactor 2, and the hydrogenation reaction product is separated by liquid collector 4, so that the liquid phase product exits the system and the separated gas phase is collected; and, according to the concentration of carbon dioxide in the separated gas phase, the flow direction of the separated gas phase can be flexibly adjusted to improve the carbon dioxide conversion rate.

[0052] In one embodiment, the conditions for the hydrogenation reaction include: a reaction temperature of 50-100°C, preferably 60-80°C; a reactant residence time of 5-10 seconds, preferably 7-8 seconds; and a light irradiance of 20-200 W / m² from the tunable wavelength light source 24. 2 The preferred value is 50~150W / m 2 .

[0053] In this embodiment, the hydrogenation reaction rate increases with increasing reaction temperature because the activation energy decreases, molecular motion speed increases, and the collision frequency between reactant molecules increases. However, the reaction rate slows down when the temperature exceeds a critical point because the photocatalyst deactivates at high temperatures. Therefore, the heating layer is improved to be temperature-adjustable, and the optimal reaction temperature must be selected according to different catalysts to maximize reaction efficiency. Only light absorbed by the reaction system can trigger the photochemical reaction, and the system exhibits selective light absorption with a suitable wavelength.

[0054] In one embodiment, the hydrogen can be produced by electrolysis of water driven by renewable energy sources such as solar, wind, and biomass power generation, wherein the concentration of the hydrogen is 90% by volume or higher. The carbon dioxide can be sourced from one or more of the following: burning fossil fuels, industrial production, agricultural activities, and energy consumption, wherein the concentration of the carbon dioxide is 90% by volume or higher.

[0055] In this embodiment, since the hydrogen raw material is generated by water electrolysis, and the electricity generated by the aforementioned renewable energy source is unstable, there will be fluctuations in the hydrogen concentration. Therefore, the ratio of carbon dioxide to hydrogen in the hydrogenation reaction material obtained by mixing in gas mixer 1 is unstable. By using the method disclosed herein, the reaction conditions of the hydrogenation reaction can be flexibly adjusted according to the above ratio, and the problem of product quality deterioration caused by fluctuations in the quality of raw materials can be avoided.

[0056] In one embodiment, the molar ratio of hydrogen and carbon dioxide entering the gas mixer 1 is (2~4):1, preferably (2.5~3.5):1.

[0057] In one embodiment, the photocatalyst comprises one or more of titanium dioxide particles, zinc oxide particles, and tin oxide particles, preferably titanium dioxide particles. Preferably, the average particle size of the photocatalyst is 10-50 nm, more preferably 20-40 nm.

[0058] In this embodiment, when light with energy greater than or equal to the band gap irradiates the photocatalyst nanoparticles, electrons in their valence band will be excited and jump to the conduction band, leaving relatively stable holes in the valence band, thereby forming electron-hole pairs, which cause the carbon dioxide reduction reaction to occur. Therefore, the hydrogenation reaction of carbon dioxide and hydrogen needs to be carried out in the presence of a photocatalyst.

[0059] In one embodiment, the method further includes: allowing the hydrogenation reaction product to enter a liquid collector 4 under the action of the blower 3 for gas-liquid separation to obtain a liquid product and a separated gas phase; allowing the liquid product to exit the system; allowing a carbon dioxide concentration detector to detect the carbon dioxide concentration in the separated gas phase; and transmitting the detection result to a control unit 9. The control unit compares the result with a collection threshold and adjusts the system to either a first operating state or a second operating state. Specifically: When the carbon dioxide concentration in the separated gas phase is less than the collection threshold, the control unit 9 adjusts the system to a first operating state, allowing the separated gas phase to directly enter the gas collector 5. When the carbon dioxide concentration in the separated gas phase is greater than the collection threshold, the control unit 9 adjusts the system to a second operating state, allowing the separated gas phase to return to the photocatalytic reactor 2 to continue reacting until the carbon dioxide concentration in the separated gas phase is less than the collection threshold, at which point the separated gas phase enters the gas collector 5.

[0060] In this embodiment, the control unit 9 flexibly controls the flow direction of the separated gas phase. On the one hand, it can make full use of the reactants in the hydrogenation reaction and improve the conversion rate of carbon dioxide. On the other hand, it can reduce the volume of the collected gas, reduce the volume of the gas collector 5 and the storage difficulty, thereby reducing equipment investment and saving costs.

[0061] In one embodiment, the system of this disclosure cycles 2 to 5 times when it is in the second working state, preferably 3 to 4 times.

[0062] In one embodiment, a carbon dioxide concentration detector at the inlet of the photocatalytic reactor detects the carbon dioxide concentration in the hydrogenation reaction product, and transmits the detected result to a control unit 9, which compares the result with a first threshold and a second threshold.

[0063] In one embodiment, the obtained liquid product is fed into a fractionation device for separation, which can yield hydrocarbons with high purity. These hydrocarbons can be used directly as fuel or made into chemical reagents.

[0064] In one embodiment, the gaseous material collected by the gas collector 5 is fed into a hydrogen purification device for hydrogen purification treatment and then returned to the gas mixer for continued use.

[0065] In one embodiment, the liquid phase product obtained in liquid collector 4 mainly consists of hydrocarbons and water. The separated gas phase obtained in gas collector 5 mainly consists of hydrocarbons, hydrogen, and carbon dioxide. The hydrocarbons primarily include one or more of methane, ethylene, ethane, and propylene.

[0066] In one implementation, such as Figure 1 , Figure 2 and Figure 4 As shown, the methods for carrying out the catalytic reduction hydrogenation reaction of carbon dioxide include: Carbon dioxide and hydrogen are mixed in gas mixer 1 to obtain hydrogenation reaction material; wherein the molar ratio of hydrogen to carbon dioxide is (2~4):1; The hydrogenation reactants are introduced into the photocatalytic reactor 2 and buffered in the feed chamber 25 before entering the interior of multiple catalyst-coated optical fibers 23. Under the illumination of a tunable wavelength light source 24, the reactants contact the attached photocatalyst to undergo a hydrogenation reaction, and the resulting hydrogenation product enters the discharge chamber 26. The conditions for the hydrogenation reaction include: a reaction temperature of 50-100°C, a reactant residence time of 5-10 seconds, and an illumination intensity of 20-200 W / m² from the tunable wavelength light source 24. 2 ; The carbon dioxide concentration detector at the inlet of the photocatalytic reactor detects the carbon dioxide concentration in the hydrogenation reaction product and transmits the detection result to the control unit 9, which compares the result with a first threshold and a second threshold. The hydrogenation reaction products are introduced into a liquid collector 4 by the blower 3 for gas-liquid separation, resulting in a liquid product and a separated gas phase. The liquid product exits the system, and a carbon dioxide concentration detector detects the carbon dioxide concentration in the separated gas phase. The detection result is transmitted to a control unit 9, which compares the result with a collection threshold and adjusts the system to either a first or a second operating state. Specifically: when the carbon dioxide concentration in the separated gas phase is less than the collection threshold, the control unit 9 adjusts the system to the first operating state, allowing the separated gas phase to directly enter the gas collector 5. When the carbon dioxide concentration in the separated gas phase is greater than the collection threshold, the control unit 9 adjusts the system to the second operating state, allowing the separated gas phase to return to the photocatalytic reactor 2 for further reaction until the carbon dioxide concentration in the separated gas phase is less than the collection threshold, at which point the separated gas phase enters the gas collector 5. The collection threshold is 10-30% by volume.

[0067] The present disclosure is further illustrated by the following examples, but the present disclosure is not limited thereto. The hydrogen used in the present disclosure is produced by electrolyzing water with electricity generated by a wind turbine, and has a purity of 98% by volume; the carbon dioxide used in the present disclosure is obtained by burning fossil fuels and has a purity of 98% by volume.

[0068] Example 1 use Figure 4 The system performs a carbon dioxide catalytic reduction and hydrogenation reaction, wherein the photocatalytic reactor used is such as... Figure 1 and Figure 2 As shown, the shell of the photocatalytic reactor has a cylindrical structure with a height of 1.2m and a cross-sectional diameter of 1.0m. The reaction chamber has a height of 0.8m and a cross-sectional diameter of 0.8m. The photocatalytic reactor uses a catalyst-coated optical fiber as shown in the figure. Figure 3As shown, the catalyst-coated optical fiber has a length of 0.9m, an inner diameter of 5mm, and the photocatalyst attached to the inner wall is titanium dioxide particles with a particle size of 30nm.

[0069] Methods for the catalytic reduction hydrogenation of carbon dioxide include: Carbon dioxide and hydrogen are mixed in gas mixer 1 to obtain hydrogenation reaction material; wherein the molar ratio of hydrogen to carbon dioxide is 3:1. The hydrogenation reactants are introduced into the photocatalytic reactor 2, buffered in the feed chamber 25, and then enter the interior of multiple catalyst-coated optical fibers 23. Under the illumination of a tunable wavelength light source 24, they contact the attached photocatalyst to undergo a hydrogenation reaction, and the resulting hydrogenation product enters the discharge chamber 26. The conditions for the hydrogenation reaction include: a reaction temperature of 70°C, a reactant residence time of 7 seconds, and an illumination intensity of 50 W / m² for the tunable wavelength light source 24. 2 ; The carbon dioxide concentration detector at the inlet of the photocatalytic reactor detects the carbon dioxide concentration in the hydrogenation reaction product and transmits the detection result to the control unit 9, which compares the result with a first threshold and a second threshold. The hydrogenation reaction products are introduced into a liquid collector 4 by the blower 3 for gas-liquid separation, yielding a liquid product and a separated gas phase. The liquid product exits the system, and a carbon dioxide concentration detector monitors the carbon dioxide concentration in the separated gas phase. The result is transmitted to a control unit 9, which compares the result with a collection threshold and adjusts the system to either a first or a second operating state. Specifically: when the carbon dioxide concentration in the separated gas phase is less than the collection threshold, the control unit 9 adjusts the system to the first operating state, allowing the separated gas phase to directly enter the gas collector 5. When the carbon dioxide concentration in the separated gas phase is greater than the collection threshold, the control unit 9 adjusts the system to the second operating state, allowing the separated gas phase to return to the photocatalytic reactor 2 for further reaction until the carbon dioxide concentration in the separated gas phase is less than the collection threshold, at which point the separated gas phase enters the gas collector 5. The collection threshold is 20% of the volume.

[0070] Example 2 use Figure 4 The system performs a carbon dioxide catalytic reduction hydrogenation reaction, and the method for performing the carbon dioxide catalytic reduction hydrogenation reaction is the same as in Example 1, except that no carbon dioxide concentration detector is set at the inlet of the photocatalytic reactor of the system and no control unit is included, so that the reaction conditions of the photocatalytic reactor do not change with the concentration of carbon dioxide in the hydrogenation reaction material.

[0071] Comparative Example 1 use Figure 4 The system performs carbon dioxide catalytic reduction hydrogenation reaction, and the method for performing carbon dioxide catalytic reduction hydrogenation reaction is the same as in Example 1, except that no circulating gas phase pipeline is set in the system so that the separated gas phase from the gas phase outlet of the liquid collector 4 is directly sent to the gas collector 5.

[0072] Comparative Example 2 use Figure 4 The system performs the catalytic reduction and hydrogenation reaction of carbon dioxide, the difference being that it uses... Figure 5 The photocatalytic reactor in the reactor is used for hydrogenation. The reactor has a cylindrical structure and includes, from the outside to the inside, a heating layer 29, a reflective layer 30, a reaction tube 31, and a light source 32. The heating layer 29 is a hollow cylinder used to provide and maintain the required temperature for the entire reactor. The reflective layer 30 is attached to the inner wall of the heating layer 29 and is used to reflect the light emitted by the light source 32 multiple times. The light source 32 is rod-shaped and extends coaxially with the heating layer 29 to provide light radiation to perform the photocatalytic reaction. The reaction tube 31 is a hollow tube and extends spirally around the light source 32 through the entire heating layer. In addition, the two ends of the reaction tube 31 have a material inlet and a material outlet, respectively, and its inner wall is coated with a photocatalyst, thereby keeping the contents of the hollow tube spirally transported and reacting synchronously.

[0073] Table 1. Properties of the products in the examples and comparative examples.

[0074] As shown in Table 1, a comparison of the data from Examples 1-2 and Comparative Examples 1-2 shows that the method of this disclosure can improve the hydrogenation reaction effect of carbon dioxide. Specifically, a comparison of the data from Examples 1 and 2 shows that flexibly adjusting the hydrogenation reaction conditions according to the carbon dioxide concentration of the hydrogenation reactant at the inlet of the photocatalytic reactor can further improve the hydrogenation reaction effect of carbon dioxide; a comparison of the data from Examples 1 and Comparative Example 1 shows that flexibly adjusting the flow of the separated gas phase to the gas collector or photocatalytic reactor according to the carbon dioxide concentration of the separated gas phase obtained from the liquid collector can further improve the hydrogenation reaction effect of carbon dioxide; a comparison of the data from Examples 1 and Comparative Example 2 shows that using the photocatalytic reactor of this disclosure can further improve the hydrogenation reaction effect of carbon dioxide.

[0075] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0076] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0077] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A system for a hollow tube-type catalytic reduction and hydrogenation reaction of carbon dioxide, characterized in that, The system includes a gas mixer (1), a photocatalytic reactor (2), a fan (3), a liquid collector (4), and a gas collector (5). The photocatalytic reactor (2) includes a shell (20) with an overall cylindrical structure, a temperature regulating layer (21), a diffuse reflection layer (22), a catalyst-coated optical fiber assembly, and a tunable wavelength light source (24); the shell (20) is provided with a feed chamber (25), a reaction chamber, and a discharge chamber (26) from top to bottom; the temperature regulating layer (21) covers the outside of the reaction chamber; the diffuse reflection layer (22), the catalyst-coated optical fiber assembly, and the tunable wavelength light source (24) are arranged in sequence from the outside to the inside of the reaction chamber; The catalyst-coated fiber assembly includes multiple catalyst-coated fibers (23), and the catalyst-coated fiber (23) is a hollow tube with a photocatalyst attached to its inner wall; one end of the hollow tube extends to the feed chamber (25) to form a material inlet, and the other end of the hollow tube extends to the discharge chamber (26) to form a material outlet. The feed chamber (25) and the discharge chamber (26) are respectively provided with a feed inlet and a discharge outlet; the feed inlet is connected to the outlet of the gas mixer (1), and the discharge outlet is connected to the inlet of the blower (3); the inlet of the liquid collector (4) is connected to the outlet of the blower (3); the gas phase outlet pipeline of the liquid collector (4) is divided into a circulating gas phase pipeline and a gas phase collection pipeline; The gas phase outlet of the liquid collector (4) is connected to the feed inlet of the photocatalytic reactor (2) through the circulating gas phase pipeline; the gas phase outlet of the liquid collector (4) is connected to the inlet of the gas collector (5) through the gas phase collection pipeline. The diffuse reflection layer (22) is disposed on the inner wall of the temperature regulating layer (21); The adjustable wavelength light source (24) is arranged axially inside the reaction chamber and is coaxial with the reaction chamber; The adjustable wavelength light source (24) is coaxially arranged with the housing; The catalyst-coated optical fiber (23) is arranged axially inside the reaction chamber; The catalyst-coated optical fiber (23) has a plurality of reflective grooves (28) on its sidewall; the ratio of the width of the reflective groove (28) to the length of the catalyst-coated optical fiber (23) is (0.05~0.2):1; Multiple catalyst-coated optical fibers (23) are arranged in parallel, and the multiple catalyst-coated optical fibers (23) are arranged at intervals along the same circumference on a plane perpendicular to the axial direction; The ratio of the length of the catalyst-coated optical fiber (23) to the height of the shell is (0.6~0.8):1; The inner diameter of the catalyst-coated optical fiber (23) is 1~10mm; The system also includes a control unit (9) and a carbon dioxide concentration detector located at the inlet of the photocatalytic reactor (2); The control unit (9) is electrically connected to the carbon dioxide concentration detector, the tunable wavelength light source (24) and the temperature regulation layer (21) respectively, and is used to receive the concentration signal from the carbon dioxide concentration detector and adjust the input power of the tunable wavelength light source (24) and / or the temperature regulation layer (21) according to the concentration signal.

2. The system according to claim 1, characterized in that, The tunable wavelength light source (24) includes one or more of the following: xenon lamp light source, QTH tunable quartz halogen lamp light source, deuterium lamp light source and halogen tungsten lamp light source.

3. A method for performing a carbon dioxide catalytic reduction hydrogenation reaction using the system described in claim 1 or 2, characterized in that, The method includes: Carbon dioxide and hydrogen are mixed in a gas mixer (1) to obtain hydrogenation reaction material; the hydrogenation reaction material is then introduced into the catalyst-coated optical fiber assembly of the photocatalytic reactor (2) to contact the photocatalyst for hydrogenation reaction to obtain hydrogenation reaction product; The hydrogenation reaction product is introduced into the liquid collector (4) by the action of the blower (3) for gas-liquid separation to obtain liquid phase product and separated gas phase; When the carbon dioxide concentration in the separated gas phase is less than the collection threshold, the separated gas phase is allowed to enter the gas collector (5). When the carbon dioxide concentration in the separated gas phase is greater than the collection threshold, the separated gas phase is returned to the photocatalytic reactor (2) to continue the reaction until the carbon dioxide content in the separated gas phase is less than the collection threshold, at which point the separated gas phase enters the gas collector (5). The collection threshold is 10-30 units of volume.

4. The method according to claim 3, characterized in that, The conditions for the hydrogenation reaction include: a reaction temperature of 50~100℃, a reactant residence time of 5~10s, and a light irradiance of 20~200W / m² from the tunable wavelength light source (24). 2 .

5. The method according to claim 3, characterized in that, The photocatalyst includes one or more of titanium dioxide particles, zinc oxide particles, and tin oxide particles.

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