A system and method for multi-stage series carbon dioxide catalytic reduction hydrogenation reaction

Abstract

The present disclosure relates to a system and method for multi-stage series carbon dioxide catalytic reduction hydrogenation reaction, in which a temperature regulating layer of a photocatalytic reactor is formed between the top of a shell and a feed chamber, a discharge chamber is formed between the bottom of the shell and the temperature regulating layer, and only hollow tubular catalyst coated optical fibers with photocatalyst-attached inner walls are used to communicate between the feed chamber and the discharge chamber, so that the hydrogenation reaction material is buffered in the feed chamber and then enters the catalyst coated optical fibers to contact the catalyst for hydrogenation reaction, which can increase the specific surface area of the catalyst and the residence time of the hydrogenation reaction material in the photocatalytic reactor, thereby improving the hydrogenation reaction effect of carbon dioxide. Furthermore, multiple photocatalytic reactors are arranged in series in the photocatalytic reactor group to allow the hydrogenation reaction material to undergo multiple hydrogenation reactions in the photocatalytic reactor group, which can further improve the conversion rate of carbon dioxide.

Description

Technical Field

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

[0002] The widespread use of fossil fuels has led to massive emissions of carbon dioxide, exacerbating the greenhouse effect and severely impacting the global climate. How to effectively reduce carbon dioxide concentrations has become a major focus of attention.

[0003] In existing technologies, under light irradiation, captured carbon dioxide and green hydrogen are converted into C1-C3 organic compounds by a photocatalyst. The photocatalyst is typically a semiconductor material, excited by light, and the electrons and holes generated by the photocatalyst participate in the carbon dioxide hydrogenation reaction. When light with energy greater than or equal to the band gap irradiates semiconductor nanoparticles, the nanoparticles are excited, meaning electrons in the valence band are excited to the conduction band, leaving relatively stable holes in the valence band, thus forming electron-hole pairs and inducing the carbon dioxide reduction reaction. However, the hydrogenation reaction area in existing photocatalytic reactors and systems is relatively small, resulting in a low amount of photocatalyst or photocatalyst stacking within the hydrogenation reaction area. This leads to low light energy utilization and a small total surface area of ​​contact between the hydrogenation reactants and the catalyst, affecting the efficiency and quality of the photocatalytic reaction. Summary of the Invention

[0004] The purpose of this disclosure is to provide a system and method for a multi-stage tandem carbon dioxide catalytic reduction hydrogenation reaction, in order to solve the problems of small hydrogenation reaction area, low light utilization, small total surface area of ​​contact between hydrogenation reactants and catalyst, and inflexible hydrogenation reaction conditions in the prior art.

[0005] To achieve the above objectives, the first aspect of this disclosure provides a system for a multi-stage series carbon dioxide catalytic reduction hydrogenation reaction. The system includes a gas mixer, a photocatalytic reactor assembly, a blower, a liquid collector, and a gas collector. The photocatalytic reactor assembly includes multiple photocatalytic reactors arranged in series. Each photocatalytic reactor includes a cylindrical shell, 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 from the outside to the inside. The reaction chamber is located inside the reactor chamber. The catalyst-coated fiber optic assembly comprises multiple catalyst-coated fibers, each being a hollow tube with a photocatalyst attached to its inner wall. One end of each hollow tube extends into the feed chamber to form a material inlet, and the other end extends into 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 of the first-stage photocatalytic reactor is connected to the outlet of the gas mixer, and the discharge port of the last-stage photocatalytic reactor is connected to the inlet of the blower. The inlet of the liquid collector is connected to the outlet of the blower, and the gas phase outlet pipeline of the liquid collector is connected to the inlet of the gas collector.

[0006] 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.

[0007] 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.

[0008] Optionally, a plurality of the 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 to 0.8):1; the inner diameter of the catalyst-coated optical fiber is 1 to 10 mm.

[0009] 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.

[0010] Optionally, the system further includes a control unit and a carbon dioxide concentration detector disposed at the inlet of the photocatalytic reactor group; the number of photocatalytic reactors in the photocatalytic reactor group is three or more; the control unit is electrically connected to the carbon dioxide concentration detector, the tunable wavelength light source in each of the photocatalytic reactors and the temperature regulation layer in each of the photocatalytic reactors, respectively, for receiving the signal from the carbon dioxide concentration detector and adjusting the input power of the tunable wavelength light source and / or the temperature regulation layer in each of the photocatalytic reactors according to the signal.

[0011] The second aspect of this disclosure is 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 hydrogenation reaction material; sequentially introducing the hydrogenation reaction material into each photocatalytic reactor and contacting it with the photocatalyst attached to the catalyst-coated optical fiber assembly to perform a hydrogenation reaction, thereby obtaining a hydrogenation reaction product; and sequentially introducing the hydrogenation reaction product into a gas collector via a fan and a liquid collector.

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

[0013] Optionally, the conditions for the hydrogenation reaction include: a reaction temperature of 50–100°C, a reactant residence time of 5–10 s, and a light irradiance of 20–200 W / m² from a tunable wavelength light source. 2 .

[0014] Optionally, the method further includes a control unit adjusting the input power of the tunable wavelength light source and / or the temperature regulation layer in each photocatalytic reactor based on the concentration of carbon dioxide in the hydrogenation reactants and the number of photocatalytic reactors in the photocatalytic reactor group.

[0015] Through the above technical solution, a feed chamber is formed between the temperature regulation layer and the top of the shell of the photocatalytic reactor, and a discharge chamber is formed between the temperature regulation 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 come into contact with 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 photocatalytic reactor group is equipped with multiple photocatalytic reactors arranged in series, allowing the hydrogenation reactants to undergo multiple hydrogenation reactions within the photocatalytic reactor group, further improving the carbon dioxide conversion rate.

[0016] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0017] 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:

[0018] Figure 1 This is a schematic diagram of a cross-section of a photocatalytic reactor disclosed herein.

[0019] Figure 2 This is a top view of another photocatalytic reactor disclosed herein.

[0020] Figure 3 This is a schematic diagram of a catalyst-coated optical fiber used in a photocatalytic reactor disclosed herein.

[0021] Figure 4 This is a schematic diagram of a multi-stage series carbon dioxide catalytic reduction hydrogenation system disclosed herein.

[0022] Figure 5 This is a schematic diagram of the photocatalytic reactor used in Comparative Example 1 of this disclosure.

[0023] Explanation of reference numerals in the attached figures

[0024] 1. Gas mixer; 2. Photocatalytic reactor group; 2-1. Primary photocatalytic reactor; 2-2. Secondary photocatalytic reactor; 2-3. Tertiary photocatalytic reactor; 2-4. Quaternary photocatalytic reactor; 2-5. Fifth-stage photocatalytic reactor; 2-6. Sixth-stage photocatalytic reactor; 3. Fan; 4. Liquid collector; 5. Gas collector; 9. Control unit; 20. Shell; 21. Temperature regulation 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

[0025] 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.

[0026] 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 1In 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.

[0027] like Figure 1 and Figure 4 As shown, the first aspect of this disclosure provides a system for a multi-stage series catalytic reduction hydrogenation reaction of carbon dioxide. The system includes a gas mixer 1, a photocatalytic reactor group 2, a blower 3, a liquid collector 4, and a gas collector 5. The photocatalytic reactor group 2 includes multiple photocatalytic reactors arranged in series. Each photocatalytic reactor includes a cylindrical shell 20, a temperature regulating layer 21, a diffuse reflection layer 22, a catalyst-coated optical fiber group, and a tunable wavelength light source 24. The shell 20 contains, from top to bottom, a feed chamber 25, a reaction chamber, and a discharge chamber 26. The temperature regulating layer 21 covers the outside of the reaction chamber. The diffuse reflection layer 22, the catalyst-coated optical fiber group, and the tunable wavelength light source 24 are arranged from the outside to the inside. Inside the reaction chamber; the catalyst-coated fiber assembly includes multiple catalyst-coated fibers 23, each of which 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 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 of the first-stage photocatalytic reactor is connected to the outlet of the gas mixer 1, and the discharge outlet of the last-stage photocatalytic reactor 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; and the gas phase outlet pipeline of the liquid collector 4 is connected to the inlet of the gas collector 5.

[0028] Through the above technical solution, a feed chamber is formed between the temperature regulation layer and the top of the shell of the photocatalytic reactor, and a discharge chamber is formed between the temperature regulation 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 come into contact with the catalyst for hydrogenation. This increases the total surface area of ​​contact between the hydrogenation reactants and the photocatalyst, while also increasing the residence time of the hydrogenation reactants in the photocatalytic reactor, thereby improving the hydrogenation effect of carbon dioxide. Furthermore, the photocatalytic reactor group is equipped with multiple photocatalytic reactors arranged in series, allowing the hydrogenation reactants to undergo multiple hydrogenation reactions within the photocatalytic reactor group, further improving the carbon dioxide conversion rate.

[0029] 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.

[0030] 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 group 2.

[0031] 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.

[0032] 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 3 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.

[0033] In one embodiment, the number of photocatalytic reactors in the photocatalytic reactor group 2 is three or more; for example, the number of photocatalytic reactors in the photocatalytic reactor group 2 is three, four, five or six.

[0034] In one specific embodiment, the photocatalytic reactor group 2 of this disclosure comprises six photocatalytic reactors: a primary photocatalytic reactor 2-1, a secondary photocatalytic reactor 2-2, a tertiary photocatalytic reactor 2-3, a quaternary photocatalytic reactor 2-4, a quinary photocatalytic reactor 2-5, and a sixth-stage photocatalytic reactor 2-6. The inlet of the primary photocatalytic reactor 2-1 is connected to the outlet of the gas mixer 1; the outlet of the primary photocatalytic reactor 2-1 is connected to the inlet of the secondary photocatalytic reactor 2-2; the outlet of the secondary photocatalytic reactor 2-2 is connected to the inlet of the tertiary photocatalytic reactor 2-3; the outlet of the tertiary photocatalytic reactor 2-3 is connected to the inlet of the quaternary photocatalytic reactor 2-4; the outlet of the quaternary photocatalytic reactor 2-4 is connected to the inlet of the quinary photocatalytic reactor 2-5; the outlet of the quinary photocatalytic reactor 2-5 is connected to the inlet of the sixth-stage photocatalytic reactor 2-6; and the outlet of the sixth-stage photocatalytic reactor 2-6 is connected to the inlet of the fan 3.

[0035] like Figure 1 and Figure 2 As shown, the temperature regulating layer 21 in the photocatalytic reactor is generally cylindrical in shape. This cylindrical structure is disposed 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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 1-10 mm, preferably 5-10 mm, and more preferably 7-8 mm.

[0048] 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.

[0049] 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.

[0050] In one embodiment, the input power of the tunable wavelength light source 24 and / or the temperature regulation layer 21 in each photocatalytic reactor can be the same. Specifically, the system further includes a control unit 9 and a carbon dioxide concentration detector at the inlet of the photocatalytic reactor group 2. The control unit 9 is electrically connected to the carbon dioxide concentration detector, the tunable wavelength light source 24 in each photocatalytic reactor, and the temperature regulation layer 21 in each photocatalytic reactor, for receiving signals from the carbon dioxide concentration detector and adjusting the input power of the tunable wavelength light source 24 and / or the temperature regulation layer 21 in each photocatalytic reactor according to the signals.

[0051] In this embodiment, before the hydrogenation reaction, the photocatalytic reaction temperature is 50–100°C and the light irradiation intensity is 20–200 W / m². 2 In the input control unit 9, after the reaction temperature and light irradiation intensity in each photocatalytic reactor reach the input value, the control unit 9 receives the carbon dioxide concentration of the hydrogenation reaction material detected by the carbon dioxide concentration detector installed at the inlet of the photocatalytic reactor group 2. When the carbon dioxide concentration in the hydrogenation reaction material is less than a first threshold, the reaction temperature and / or the light irradiation intensity of the hydrogenation reaction are increased; the first threshold is 28-33% by volume. When the carbon dioxide concentration in the hydrogenation reaction material is greater than a second threshold, the reaction temperature and / or the light irradiation intensity of the hydrogenation reaction are decreased; the second threshold is 20-25% by volume.

[0052] In another embodiment, the input power of the tunable wavelength light source 24 and / or the temperature regulation layer 21 in each photocatalytic reactor can also decrease sequentially in the order of primary photocatalytic reactor 2-1, secondary photocatalytic reactor 2-2, tertiary photocatalytic reactor 2-3, quaternary photocatalytic reactor 2-4, quinary photocatalytic reactor 2-5 and sixth photocatalytic reactor 2-6. Specifically, the input power ratio of the temperature regulating layer 21 in the first-stage photocatalytic reactor 2-1, the second-stage photocatalytic reactor 2-2, the third-stage photocatalytic reactor 2-3, the fourth-stage photocatalytic reactor 2-4, the fifth-stage photocatalytic reactor 2-5, and the sixth-stage photocatalytic reactor 2-6 can be 1:(0.8~0.9):(0.7~0.8):(0.6~0.7):(0.5~0.6):(0.4~0.5), and the input power ratio of the tunable wavelength light source 24 can be 1:(0.8~0.9):(0.7~0.8):(0.6~0.7):(0.5~0.6):(0.4~0.5).

[0053] In this embodiment, before the hydrogenation reaction, the photocatalytic reaction temperature is 70°C and the light irradiation intensity is 50 W / m². 2 The corresponding proportions of each photocatalytic reactor are input into the control unit 9. When the temperature and light irradiance of each photocatalytic reactor reach the input values, the control unit 9 adjusts the reaction temperature and light irradiance of each photocatalytic reactor according to the input proportions. Then, the control unit 9 receives the carbon dioxide concentration of the hydrogenation reaction material detected by the carbon dioxide concentration detector at the inlet of the photocatalytic reactor group 2. When the carbon dioxide concentration in the hydrogenation reaction material is less than a first threshold, the reaction temperature and / or light irradiance of the hydrogenation reaction in each photocatalytic reactor are increased according to the corresponding proportions. The first threshold is 28-33% by volume. When the carbon dioxide concentration in the hydrogenation reaction material is greater than a second threshold, the reaction temperature and / or light irradiance of the hydrogenation reaction in each photocatalytic reactor are decreased according to the corresponding proportions. The second threshold is 20-25% by volume.

[0054] The second aspect of this disclosure is 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; sequentially introducing the hydrogenation reaction material into each photocatalytic reactor and contacting it with the photocatalyst attached to the catalyst-coated optical fiber assembly to perform a hydrogenation reaction, thereby obtaining a hydrogenation reaction product; and sequentially introducing the hydrogenation reaction product into a gas collector 5 via a fan 3 and a liquid collector 4.

[0055] In this embodiment, the hydrogenation reactants are subjected to hydrogenation reaction in a photocatalytic reactor group 2 consisting of multiple photocatalytic reactors connected in series, and the resulting hydrogenation reaction products are separated by a liquid collector 4. The resulting liquid phase product exits the system and the separated gas phase is collected. This allows the hydrogenation reactants to undergo multiple hydrogenation reactions in multiple reactors, thereby improving the conversion rate of carbon dioxide.

[0056] In one embodiment, the input power of the tunable wavelength light source 24 and / or the temperature regulating layer 21 in each photocatalytic reactor is the same, or it can decrease sequentially in the order of primary photocatalytic reactor 2-1, secondary photocatalytic reactor 2-2, tertiary photocatalytic reactor 2-3, quaternary photocatalytic reactor 2-4, quinary photocatalytic reactor 2-5, and sixth-stage photocatalytic reactor 2-6. Preferably, the input power of the tunable wavelength light source 24 and / or the temperature regulating layer 21 in each photocatalytic reactor is the same. Specifically, 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 s, preferably 7–8 s; and a light irradiance of 20–200 W / m² for the tunable wavelength light source 24. 2 Preferably, it is 50-150W / m 2 .

[0057] 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.

[0058] In one embodiment, the hydrogen is obtained by electrolysis of water driven by renewable energy sources such as solar, wind, and biomass power generation, wherein the concentration of the hydrogen can be 90% by volume or higher. The carbon dioxide can be obtained 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.

[0059] 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.

[0060] In one embodiment, the molar ratio of hydrogen and carbon dioxide feed into the gas mixer 1 is (2-4):1, preferably (2.5-3.5):1.

[0061] 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.

[0062] 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.

[0063] In one embodiment, the method further includes: allowing the hydrogenation reaction product to enter the liquid collector 4 under the action of the blower 3 for gas-liquid separation; allowing the obtained liquid phase product to enter the fractionation device for separation processing to obtain hydrocarbons with high purity, which can be used directly as fuel or made into chemical reagents; allowing the liquid phase product to exit the system; and allowing the separated gas phase to enter the gas collector 5.

[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:

[0067] Carbon dioxide and hydrogen are mixed in gas mixer 1 to obtain hydrogenation reaction material; wherein the molar ratio of carbon dioxide to hydrogen is (2-4):1.

[0068] The photocatalytic reaction temperature is 50–100℃, and the light irradiance is 20–200 W / m². 2 In the input control unit 9, after the reaction temperature and light irradiation intensity in each photocatalytic reactor reach the input value, the control unit 9 receives the carbon dioxide concentration of the hydrogenation reaction material detected by the carbon dioxide concentration detector installed at the inlet of the photocatalytic reactor group 2. When the carbon dioxide concentration in the hydrogenation reaction material is less than a first threshold, the reaction temperature and / or the light irradiation intensity of the hydrogenation reaction are increased; the first threshold is 30% by volume. When the carbon dioxide concentration in the hydrogenation reaction material is greater than a second threshold, the reaction temperature and / or the light irradiation intensity of the hydrogenation reaction are decreased; the second threshold is 22% by volume. The residence time of the hydrogenation reaction material is 7 seconds.

[0069] The hydrogenation reaction material is fed into the first-stage photocatalytic reactor of the photocatalytic reactor group 2, and after being buffered in the feed chamber 25 of the first-stage photocatalytic reactor, it enters the interior of multiple catalyst-coated optical fibers 23. Under the light irradiation of the tunable wavelength light source 24, it comes into contact with the attached photocatalyst to carry out the hydrogenation reaction, and the resulting material enters the discharge chamber 26. Furthermore, the material obtained from the first-stage photocatalytic reactor enters the next-stage photocatalytic reactor to continue the hydrogenation reaction, until the material obtained from the last-stage photocatalytic reactor is the hydrogenation reaction product.

[0070] The hydrogenation reaction product is introduced into a liquid collector 4 by the blower 3 for gas-liquid separation. The resulting liquid product is then introduced into a fractionation unit for further separation, yielding high-purity hydrocarbons that can be used directly as fuel or manufactured into chemical reagents. The liquid product exits the system, and the separated gas phase enters a gas collector 5. The gas phase material collected by the gas collector 5 is then introduced into a hydrogen purification unit for hydrogen purification before being returned to the gas mixer for continued use.

[0071] The present disclosure is further illustrated by the following examples, but the present disclosure is not limited thereto. The hydrogen used in this disclosure is produced by electrolyzing water using electricity generated by a wind turbine, and has a purity of 98% by volume; the carbon dioxide used in this disclosure is obtained by burning fossil fuels, and has a purity of 98% by volume.

[0072] Example 1

[0073] 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 photocatalytic reactor group contains six photocatalytic reactors. The shell of each reactor is cylindrical, 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 catalyst-coated optical fiber used in the photocatalytic reactor is as follows... Figure 3 As 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.

[0074] Methods for the catalytic reduction hydrogenation of carbon dioxide include:

[0075] 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.

[0076] The photocatalytic reaction temperature was 70℃ and the light irradiance was 50W / m². 2 In the input control unit 9, after the reaction temperature and light irradiation intensity in each photocatalytic reactor reach the input value, the control unit 9 receives the carbon dioxide concentration of the hydrogenation reaction material detected by the carbon dioxide concentration detector installed at the inlet of the photocatalytic reactor group 2. When the carbon dioxide concentration in the hydrogenation reaction material is less than a first threshold, the reaction temperature and / or the light irradiation intensity of the hydrogenation reaction are increased; the first threshold is 30% by volume. When the carbon dioxide concentration in the hydrogenation reaction material is greater than a second threshold, the reaction temperature and / or the light irradiation intensity of the hydrogenation reaction are decreased; the second threshold is 22% by volume. The residence time of the hydrogenation reaction material is 7 seconds.

[0077] The hydrogenation reaction material is fed into the first-stage photocatalytic reactor of the photocatalytic reactor group 2, and after being buffered in the feed chamber 25 of the first-stage photocatalytic reactor, it enters the interior of multiple catalyst-coated optical fibers 23. Under the light irradiation of the tunable wavelength light source 24, it comes into contact with the attached photocatalyst to carry out the hydrogenation reaction, and the resulting material enters the discharge chamber 26. Furthermore, the material obtained from the first-stage photocatalytic reactor enters the next-stage photocatalytic reactor to continue the hydrogenation reaction, until the material obtained from the last-stage photocatalytic reactor is the hydrogenation reaction product.

[0078] The hydrogenation reaction product is introduced into a liquid collector 4 by the blower 3 for gas-liquid separation. The resulting liquid product is then introduced into a fractionation unit for further separation, yielding high-purity hydrocarbons that can be used directly as fuel or manufactured into chemical reagents. The liquid product exits the system, and the separated gas phase enters a gas collector 5. The gas phase material collected by the gas collector 5 is then introduced into a hydrogen purification unit for hydrogen purification before being returned to the gas mixer for continued use.

[0079] Example 2

[0080] 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 group 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.

[0081] Comparative Example 1

[0082] 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 this embodiment replaces the photocatalytic reactor in Example 1 for hydrogenation. This reactor has a cylindrical structure and, from the outside in, includes 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 interior. The reflective layer 30 is attached to the inner wall of the heating layer 29 and is used to perform multiple reflections of the light emitted by the light source 32. The light source 32 is rod-shaped and extends coaxially with the heating layer 29 to provide illumination for the photocatalytic reaction. The reaction tube 31 is a hollow tube and extends spirally around the light source 32 through the entire heating layer. Furthermore, the reaction tube 31 has a material inlet and a material outlet at both ends, and its inner wall is coated with a photocatalyst, thereby maintaining a spiral transport and synchronous reaction within the hollow tube.

[0083] Table 1. Properties of the products in the examples and comparative examples.

[0084]

[0085]

[0086] As shown in Table 1, a comparison of the data from Examples 1-2 and Comparative Example 1 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 by flexibly adjusting the hydrogenation reaction conditions of the photocatalytic reactor according to the carbon dioxide concentration of the hydrogenation reactant at the inlet of the photocatalytic reactor group, the hydrogenation reaction effect of carbon dioxide can be further improved; a comparison of the data from Examples 1 and Comparative Example 1 shows that the photocatalytic reactor of this disclosure can further improve the hydrogenation reaction effect of carbon dioxide.

[0087] 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.

[0088] 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.

[0089] 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 multi-stage tandem carbon dioxide catalytic reduction hydrogenation reaction, characterized in that, The system includes a gas mixer (1), a photocatalytic reactor group (2), a fan (3), a liquid collector (4), and a gas collector (5); The photocatalytic reactor group (2) includes multiple photocatalytic reactors arranged in series; The photocatalytic reactor includes a cylindrical shell (20), a temperature regulating layer (21), a diffuse reflection layer (22), a catalyst-coated fiber optic 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 fiber optic assembly, and the tunable wavelength light source (24) are arranged 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 of the first-stage photocatalytic reactor is connected to the outlet of the gas mixer (1), and the discharge outlet of the last-stage photocatalytic reactor 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 connected to the inlet of the gas collector (5); 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 (20); 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 housing (20) 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 group (2); The number of photocatalytic reactors in the photocatalytic reactor group (2) is three or more; The control unit (9) is electrically connected to the carbon dioxide concentration detector, the tunable wavelength light source (24) in each of the photocatalytic reactors and the temperature regulation layer (21) in each of the photocatalytic reactors, respectively, for receiving the signal from the carbon dioxide concentration detector and adjusting the input power of the tunable wavelength light source (24) and / or the temperature regulation layer (21) in each of the photocatalytic reactors according to the 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: After carbon dioxide and hydrogen are mixed in a gas mixer (1), hydrogenation reaction material is obtained; The hydrogenation reactants are sequentially introduced into each photocatalytic reactor and come into contact with the photocatalyst attached to the catalyst-coated optical fiber assembly to carry out the hydrogenation reaction, thereby obtaining the hydrogenation reaction products. The hydrogenation reaction products are sequentially passed through a blower (3) and a liquid collector (4) into a gas collector (5).

4. 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.

5. 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 .

6. The method according to claim 3, characterized in that, The method further includes a control unit (9) adjusting the input power of the tunable wavelength light source (24) and / or the temperature regulation layer (21) in each photocatalytic reactor according to the concentration of carbon dioxide in the hydrogenation reactant and the number of photocatalytic reactors in the photocatalytic reactor group (2).

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