Flat plate type photocatalytic reaction device based on capillary self-driving and phase change circulation

Abstract

The invention belongs to the technical field of photocatalytic reactors, and particularly relates to a flat plate type photocatalytic reaction device based on capillary self-driving and phase change circulation, which comprises a hollow cavity, a liquid storage cavity, a porous reaction core layer and a condensation light transmission mechanism. The porous reaction core layer is used for self-driving and pumping the reaction liquid in the liquid storage cavity by virtue of capillary force, and is subjected to catalytic reaction under illumination; solar energy drives liquid evaporation phase change, the evaporation phase change absorbs excess heat in a reaction system, and accurate and passive temperature control is achieved; and the generated steam is condensed at the condensation light-transmitting mechanism to realize gas-liquid separation. By coupling capillary self-driven and reaction heat-driven phase change circulation, the systematic problems of strong external dependence, low mass transfer efficiency and extensive heat management of a traditional photocatalytic reactor are solved in a passive system, and unification of structure simplification and performance improvement is realized.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic reactor technology, and particularly relates to a flat-plate photocatalytic reaction device based on capillary self-drive and phase change cycle. Background Technology

[0002] Photocatalysis, as a green and environmentally friendly technology, has shown broad application prospects in environmental governance and energy conversion. Currently, the key bottleneck to achieving large-scale application of this technology lies in developing efficient, low-consumption, and stable photocatalytic reactors. Current mainstream photocatalytic reactors, such as suspended, fixed-bed, and various fluidized-bed reactors, have revealed several common fundamental technical defects in their pursuit of higher efficiency.

[0003] First, these systems are highly dependent on external active energy input, generally requiring mechanical pumps and stirrers to maintain reactant transport and mixing, and relying on independent heat exchange units to manage the heat released by the reaction. This not only leads to high system energy consumption and complex structure but also reduces operational reliability. Second, their core reaction mechanism is limited by slow molecular diffusion mass transfer, and there is a physical bottleneck in the rate at which reactants move to the catalyst surface and products leave the active sites, which easily leads to a "product inhibition" effect, restricting further improvement in reaction kinetics. In addition, the heat generated by the reaction is usually regarded as "waste heat" that needs to be removed and is not effectively utilized, resulting in energy waste and easily causing local overheating and deactivation of the catalyst surface.

[0004] Therefore, there is an urgent need for a planar photocatalytic reaction device based on capillary self-drive and phase change cycle to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a planar photocatalytic reaction device based on capillary self-drive and phase change cycle, suitable for liquid-phase driven photocatalytic reactions, such as water splitting to produce hydrogen, water oxidation, CO2 reduction, and organic matter degradation, to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention provides the following solution: A planar photocatalytic reaction device based on capillary self-drive and phase change cycle includes: A hollow cavity, the bottom of which is connected to a liquid storage chamber through a porous reaction core layer, the top of which is connected to a condensation and light-transmitting mechanism, and the hollow cavity is in a negative pressure environment; The porous reaction core layer includes a catalyst support layer, a photocatalyst, and a capillary structure layer. The catalyst support layer has a porous structure, the capillary structure layer is fixed at the bottom of the catalyst support layer, the photocatalyst is coated on the surface of the catalyst support layer, and the capillary structure layer extends into the liquid storage cavity and is immersed in the reaction liquid stored in the liquid storage cavity. The porous reaction core layer is fixed to the bottom of the hollow cavity by a support structure; Light passes through the condensation and light-transmitting mechanism and irradiates the catalyst support layer. The reaction liquid moves through the capillary structure layer to the catalyst support layer. The reaction liquid undergoes a photocatalytic reaction under the irradiation of the photocatalyst and light to produce a vapor mixture. The vapor mixture enters the upper part of the hollow cavity and contacts the condensation end of the condensation and light-transmitting mechanism. The liquid phase reactants in the vapor mixture condense upon cooling, and the gas in the vapor mixture is discharged through the gas outlet connected to the hollow cavity.

[0007] The catalyst support layer is a porous material with high porosity (>80%), large specific surface area, and thin thickness (3-5mm), and can be integrated with the capillary structure layer. The surface and skeleton of the catalyst support layer are provided with photocatalysts. The bottom of the porous reaction core layer extends into the liquid storage cavity and is immersed in the reaction liquid stored in the liquid storage cavity. The porous reaction core layer is fixed to the bottom of the hollow cavity by a support column; Light passes through the condensation and light transmission mechanism and irradiates the porous reaction core layer, causing the reaction liquid to undergo a photocatalytic reaction. The vapor products enter the upper part of the hollow cavity and come into contact with the condensation end of the condensation and light transmission mechanism, causing the liquid phase products / liquid phase reactants in the vapor, such as water, to condense upon cooling. The gaseous products are then collected from the gas outlet.

[0008] Optionally, the condensation and light transmission mechanism includes a glass cover plate for light to pass through. A cover body is coaxially fixed to the outer edge of the glass cover plate, and a coolant tank is coaxially arranged on the cover body. Coolant flows in the coolant tank, and the coolant is heat exchanged with the edge of the glass cover plate. The cover is also provided with a liquid collection tank, which is located in the hollow cavity, and the liquid inlet end of the liquid collection tank is connected to the bottom edge of the glass cover.

[0009] Optionally, the support structure includes multiple support columns, the bottom of which is fixed to the bottom wall of the liquid storage cavity; The porous reaction core layer is fixed on the plurality of support columns.

[0010] Optionally, the top of the hollow cavity is connected to an air outlet.

[0011] Optionally, the liquid collection tank is connected to a flow guide.

[0012] Optionally, the liquid storage chamber is connected to a liquid inlet.

[0013] Optionally, the liquid outlet of the guide port is connected to the liquid inlet of the reflux device, and the liquid outlet of the reflux device can be connected to the liquid storage chamber.

[0014] Optionally, the bottom of the glass cover is coated with a hydrophobic layer, and the glass cover is provided with multiple hydrophilic stripes, which are arranged radially from the center on the bottom of the glass cover.

[0015] Optionally, the support column is made of either copper or aluminum.

[0016] Compared with existing technologies, the core advantage of this invention lies in its ability to natively integrate and synergistically enhance functions that traditionally require multiple independent subsystems (such as transfer pumps, mixers, heat exchangers, and separators) within a completely passive, flat, sealed unit without moving parts. Its complete reaction process forms a self-circulating system: the liquid is first automatically pumped by capillary force to a porous reaction layer loaded with a catalyst; a catalytic reaction occurs under light, producing vapor from which the gas is discharged at the top outlet, while the liquid-phase reactants / products in the vapor are condensed and flow back to the system starting point by gravity, completing the cycle and achieving separation. This device provides a highly integrated, passively operated innovative solution for photocatalytic reactions. Its core advantage stems from the novel synergy between capillary self-pumping and photothermal-induced phase transition. The following detailed explanation uses photocatalytic water splitting for hydrogen production as an example: 1. Achieving continuous reactant supply and product mass transfer separation: The porous capillary structure continuously and uniformly transports reaction water to the entire catalyst surface through capillary force, ensuring the wetting of reaction sites. Under illumination, part of the light energy absorbed by the catalyst is used to drive the photocatalytic reaction, while the other part is inevitably converted into photothermal energy, causing the interfacial water film to undergo controlled evaporation. This process is crucial for hydrogen production: the generated water vapor and hydrogen products enter the vapor chamber together, achieving instantaneous stripping of hydrogen from the catalyst surface and efficient enrichment in the gas phase. This completely solves the core bottleneck of slow hydrogen bubble aggregation and desorption in traditional liquid-phase reactions, greatly improving the mass transfer rate and reaction kinetics.

[0017] 2. Achieving precise temperature control and energy reuse in the reaction system: Although the water splitting reaction is an endothermic process, the photothermal effect of the catalyst can cause the system temperature to rise. In this device, interfacial evaporation phase change actively absorbs this excess photothermal energy, effectively preventing local overheating of the catalyst by utilizing the latent heat of phase change, and stabilizing the reaction temperature within the optimal window. This is not utilizing "reaction waste heat," but rather redistributing the input light energy, transforming the harmful risk of overheating into a beneficial driving force for phase change, thus achieving in-situ energy management.

[0018] 3. Achieving a high degree of system simplification and pre-enrichment of hydrogen products: The device integrates water transport, photolysis reaction, in-situ separation of hydrogen and steam mixtures, and system temperature control into a passively operating flat-plate unit. The generated hydrogen and steam mixture allows for steam condensation and direct extraction of hydrogen, greatly simplifying the complex reaction liquid co-collection problem in traditional hydrogen production systems. The system requires only light illumination, operates through capillary and phase change passive physical processes, has a reliable structure, and extremely low energy consumption. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the condensation and light transmission mechanism of the present invention; Figure 3 This is a schematic diagram of the hollow cavity structure in this invention; Figure 4 This is a schematic diagram of the porous reaction core layer structure of the present invention; Figure 5 This is a schematic diagram of the liquid storage chamber structure of the present invention; Among them, 1. guide port; 2. air outlet; 3. glass cover plate; 4. liquid collection tank; 5. coolant; 6. support column; 7. porous reaction core layer; 8. reflux device; 9. reaction liquid; 10. liquid inlet. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, taking photocatalytic water splitting for hydrogen production as an example.

[0022] Reference Figures 1 to 5 This invention discloses A planar photocatalytic reaction device based on capillary self-drive and phase change cycle includes: The hollow cavity has a liquid storage chamber at the bottom connected to the porous reaction core layer 7, and a condensation and light transmission mechanism at the top. The hollow cavity is in a negative pressure environment. Among them, the porous reaction core layer 7 includes a catalyst support layer, a photocatalyst, and a capillary structure layer. The catalyst support layer has a porous structure, the capillary structure layer is fixed at the bottom of the catalyst support layer, the photocatalyst is coated on the surface of the catalyst support layer, and the capillary structure layer extends into the liquid storage chamber and is immersed in the reaction liquid 9 stored in the liquid storage chamber. The porous reaction core layer 7 is fixed to the bottom of the hollow cavity by a support structure; Light passes through the condensation and light transmission mechanism and irradiates the catalyst support layer. The reaction liquid 9 moves to the catalyst support layer through the capillary structure layer. The reaction liquid 9 undergoes a photocatalytic reaction through the photocatalyst and light irradiation to produce a steam mixture. The steam mixture enters the upper part of the hollow cavity and comes into contact with the condensation end of the condensation and light transmission mechanism. The liquid phase reactants in the steam mixture condense upon cooling, and the gas in the steam mixture is discharged through the outlet 2 connected to the hollow cavity.

[0023] The catalyst support layer is a porous material with high porosity (>80%), large specific surface area, and thin thickness (3-5mm), and can be integrated with the capillary structure layer; a photocatalyst is provided on the surface and skeleton of the catalyst support layer; the bottom of the porous reaction core layer 7 extends into the liquid storage cavity and is immersed in the reaction liquid 9 stored in the liquid storage cavity; The porous reaction core layer 7 is fixed to the bottom of the hollow cavity by support columns; Light passes through the condensation and light transmission mechanism and shines on the porous reaction core layer 7, causing the reaction liquid 9 to undergo a photocatalytic reaction to produce steam. The steam enters the upper part of the hollow cavity and comes into contact with the condensation end of the condensation and light transmission mechanism. The liquid phase reactants / products in the steam are condensed upon cooling and collected by reflux, while the gas is collected through the gas outlet 2.

[0024] During operation, the reaction liquid 9 stored at the bottom of the reservoir is automatically pumped upwards and fully wetted by the porous reaction core layer 7 at the top, like a wick, under capillary action. This process requires no external mechanical pump. Light passes through the condensation and light-transmitting mechanism at the top and irradiates the photocatalyst loaded in the pores of the porous reaction core layer 7, triggering a photocatalytic reaction. Simultaneously, some of the light energy absorbed by the catalyst is converted into heat due to the photothermal effect, raising the temperature of the extremely thin liquid film in contact with it and inducing local micro-boiling evaporation. This instantly carries the generated gaseous products, such as hydrogen, into the gas phase and concentrates the non-volatile reactants in the water at the catalyst interface. The water vapor produced by evaporation, mixed with the hydrogen and other products, immediately detaches from the catalyst surface and enters the vapor chamber. Because the vapor diffusion rate is much faster than the liquid diffusion rate, the hydrogen is instantly "removed" from the reaction site, completely avoiding product inhibition. The mixed vapor rises freely in the vapor chamber and flows towards the cooler condensation surface. The mixed vapors come into contact with the inner surface of the temperature-controlled glass cover plate 3. The water vapor releases its latent heat of phase change and condenses into pure liquid water droplets, while non-condensable gases such as hydrogen are enriched. The condensed water droplets converge on the cover plate surface and flow into the collection tank 4. Then, under the action of gravity or a slight pressure difference, they return to the liquid distribution chamber at the bottom through a reflux device to re-enter the circulation. The entire process requires no mechanical pumps, stirrers, or external heating exchangers, achieving synergistic integration of reaction, mass transfer enhancement, product separation, and thermal management within a simple and compact flat plate structure.

[0025] As an optional implementation, the condensation and light transmission mechanism includes a glass cover plate 3 for light to pass through. A cover body is coaxially fixed to the outer edge of the glass cover plate 3. A coolant tank is coaxially arranged on the cover body. Coolant 5 flows in the coolant tank and is heat exchanged with the edge of the glass cover plate 3. The cover is also provided with a liquid collection tank 4, which is located in the hollow cavity, and the liquid inlet end of the liquid collection tank 4 is connected to the bottom edge of the glass cover plate 3.

[0026] During operation, the coolant 5 flowing through the coolant tank actively cools the edge of the glass cover plate 3, forming a stable low-temperature condensation surface on its inner surface; the rising vapor condenses into droplets here and is efficiently guided to the collection tank 4 for collection, realizing precise temperature control of the condensation process and efficient product recovery.

[0027] The liquid collection tank 4 is located at the outermost edge of the cover plate, with its opening facing upwards and a cross-section in the shape of a "J" or a hook.

[0028] The upper lip of the liquid collection tank 4 extends inward, slightly lower than the condensation surface of the glass cover plate 3 by about 0.5-1mm. In this way, the liquid droplets that slide down along the glass cover plate 3 will be naturally caught by this "lip" and guided into the tank, with almost no possibility of falling off midway.

[0029] The inner surface of the liquid collection tank 4 is treated with strong hydrophilicity to ensure that the liquid can spread quickly and be completely absorbed by the tank without rebounding or splashing out.

[0030] Furthermore, a capillary lock is installed at the inlet of the liquid collection tank 4.

[0031] A porous hydrophilic material strip, such as a fine sintered metal mesh or ceramic fiber, is embedded in the slit between the upper lip of the liquid collection tank 4 and the cover plate. It can actively "suck" any liquid that may exist in the slit through capillary force and pull it into the tank, completely preventing liquid from crawling and overflowing due to surface tension.

[0032] The cover body is made of a metal substrate such as aluminum or copper, and the glass cover plate 3 is coaxially fixed in the middle of the cover body. The cooling tank surrounds the glass cover plate 3 to ensure that the coolant 5 can flow evenly through every area of ​​the cover plate and prevent local overheating.

[0033] The cooling tank is connected to the refrigeration thermostatic bath via piping. The thermostatic bath is an integrated device containing a refrigeration compressor, heater, liquid storage tank, circulation pump, and precision temperature controller.

[0034] The temperature control process is as follows: 1. Setting: Set your desired target temperature on the thermostat bath, for example, 25.0°C.

[0035] 2. Circulation: The circulating pump in the thermostatic bath pumps the coolant 5, usually water or ethylene glycol aqueous solution, into the cover plate flow channel at a constant flow rate.

[0036] 3. Heat exchange: Coolant 5 flows in the flow channel, absorbing the latent heat released by condensation on the inner surface of the cover plate, and its own temperature rises.

[0037] 4. Adjustment: After being heated, the coolant 5 returns to the constant temperature bath. If the temperature sensor detects that the return temperature is higher than the set value, the refrigeration system is activated for cooling; if it is lower than the set value, the heater is activated. Through this continuous closed-loop feedback control, the temperature of the output coolant 5 is stabilized at the set value.

[0038] As an optional implementation, the support structure includes multiple support columns 6, the bottom of which is fixed to the bottom wall of the liquid storage cavity; The porous reaction core layer 7 is fixed on multiple support columns 6.

[0039] Multiple support columns 6 provide stable support for the porous reactive core layer 7 to prevent it from deforming.

[0040] As an optional implementation, the top of the hollow cavity is connected to an air outlet 2.

[0041] During operation, the gaseous products generated by the photocatalytic reaction converge at the top of the hollow cavity and are continuously or intermittently discharged and collected through the gas outlet 2. This effectively maintains the negative pressure environment inside the cavity, thereby continuously promoting the evaporation and phase change process of the liquid.

[0042] As an optional implementation, the liquid collection tank 4 is connected to the guide port 1.

[0043] The coolant collected in the collection tank 4 is smoothly discharged from the system or returned to the storage chamber through the guide port 1 connected to it, thereby maintaining the balance of the internal liquid circulation and the stable operation of the system.

[0044] As an optional implementation, the liquid storage chamber is connected to a liquid inlet 10.

[0045] Fresh reaction liquid 9 can be added to the storage chamber through the liquid inlet 10 to maintain the concentration and level balance of reactants in the system, and ensure that the capillary pumping and phase change cycle process can be carried out continuously and stably.

[0046] As an optional implementation, the liquid outlet of the guide port 1 is connected to the liquid inlet of the reflux device 8, and the liquid outlet of the reflux device 8 is connected to the liquid storage chamber.

[0047] After condensation, the liquid collected in the collection tank 4 enters the return device 8 through the guide port 1, which then transports it back to the storage chamber, thus forming a complete closed loop. This realizes the internal recycling of the reaction liquid 9, reduces waste liquid discharge, and improves the system's self-sufficiency and resource utilization efficiency.

[0048] As an optional implementation, the bottom of the glass cover plate 3 is coated with a hydrophobic layer, and the glass cover plate 3 is provided with multiple hydrophilic stripes, which are arranged radially from the center on the bottom of the glass cover plate 3.

[0049] The droplets formed by the condensation of steam at the bottom of the glass cover plate 3 are spherical and easy to roll due to their hydrophobic layer. They are then actively captured by the hydrophilic stripes arranged radially from the center and quickly guided to the liquid collection tank 4 at the edge, thereby greatly improving the coolant removal efficiency and maintaining the high-efficiency condensation performance of the cover plate.

[0050] A superhydrophobic coating, such as fluorinated silane, is deposited on the main body area of ​​the glass cover plate 3. This results in a large contact angle for coolant droplets (>150°), making them easy to roll under gravity and less prone to spreading and residue.

[0051] At the edge of the glass cover plate 3, in the area leading to the liquid collection tank 4, several radial or grid-like hydrophilic stripes can be machined, which can be achieved through laser etching followed by hydrophilic treatment. These stripes, like "tracks," can actively adsorb and guide droplets rolling from the hydrophobic area, quickly converging towards the liquid collection tank 4.

[0052] Furthermore, the bottom of the glass cover plate 3 is provided with a conical concave surface, the apex of which is located at the center of the bottom of the glass cover plate 3, and the bottom edge of the glass cover plate 3 is lower than the center of the glass cover plate 3. The inclination angle of its slope is 1°-3°, which is sufficient to provide effective gravity guidance without introducing significant side effects.

[0053] As an optional implementation, the support column 6 is made of either copper or aluminum.

[0054] The support column 6, made of highly thermally conductive copper or aluminum, can quickly equalize its own temperature, effectively preventing steam from condensing prematurely on its surface, ensuring that steam smoothly reaches the top condensation end, and maintaining the efficient operation of the phase change cycle.

[0055] The design goal of the steam chamber is to become an "insulated isothermal steam transport channel". Ideally, the steam generated from the bottom evaporation surface does not exchange heat with any other surface before reaching the only low-temperature condensing glass cover plate 3 at the top.

[0056] To prevent condensation inside the steam chamber, a thermal management strategy must be adopted, the core idea of ​​which is "heat preservation and temperature equalization".

[0057] Outside the reactor, a high-performance insulation layer, such as a vacuum insulation panel or aerogel felt, is applied to the shell portion corresponding to the steam chamber. This is the most basic and necessary measure to minimize heat loss and maintain the inner wall temperature.

[0058] The support column 6 is made of high thermal conductivity materials such as copper and aluminum, rather than stainless steel. The purpose is to allow heat to be quickly conducted along the column, making its overall temperature as uniform as possible and close to the steam temperature, thus reducing the temperature difference between the top and bottom.

[0059] While ensuring mechanical strength, minimize the cross-sectional area of ​​the support column 6, such as by using thin columns, to reduce its total heat conduction as a "thermal bridge".

[0060] Specifically, this device includes the following structure: The condensation and light-transmitting mechanism consists of a condensation cover plate and a collection layer, located at the top of the device. The condensation cover plate is a glass cover plate 3, with a lower surface temperature for condensing rising steam. A liquid collection tank 4 is connected to the edge of the glass cover plate 3, coaxially fitted onto the outside of the glass cover plate 3, which collects the condensed liquid droplets. A guide port 1 is connected to one side of the liquid collection tank 4 to discharge the collected liquid, and an outlet 2 is connected to the top of the liquid collection tank 4.

[0061] The central part of the hollow cavity is a steam transfer chamber, which is located between the glass cover plate 3 and the porous reaction core layer 7.

[0062] The steam transfer chamber is a flat, hollow, sealed chamber. It is supported internally by multiple support columns 6. The function of the steam transfer chamber is to provide space for steam generated from the lower layer to rise freely and reach the glass cover 3 at the top.

[0063] The porous reaction core layer 7 is a composite functional layer, comprising a catalyst support layer, a catalyst, and a capillary structure layer. The catalyst support layer is a porous material with high porosity (>80%), large specific surface area, and a thin thickness (3-5 mm), and can be integrated with the capillary structure layer. A photocatalyst is embedded in the surface and framework of the catalyst support layer. The bottom of the porous reaction core layer 7 extends into the liquid storage chamber and is immersed in the reaction liquid 9 stored within the chamber. Under light irradiation, a photocatalytic reaction occurs here, generating vapor. Its porous structure generates capillary force, automatically drawing liquid from the lower layers.

[0064] The liquid storage chamber is located at the bottom of the device. The liquid storage chamber contains the reaction liquid 9.

[0065] The storage chamber is also connected to the inlet 10, which is used to replenish fresh reaction solution 9.

[0066] Furthermore, the liquid storage chamber is connected to the outlet of the reflux device 8 on its side, and the inlet of the reflux device 8 is connected to the guide port 1. The reflux device 8 can return the liquid collected from the upper condensation to this port.

[0067] Furthermore, welding methods such as argon arc welding and laser welding are used to permanently seal the liquid collection tank 4 to the cover.

[0068] The flow guide port 1 uses a flange with an O-ring or metal face seal to ensure zero leakage at the connection point.

[0069] The working process of this device is as follows: 1. Condensation: Droplets are generated in the main area of ​​the superhydrophobic glass cover plate 3 and are spherical.

[0070] 2. Collection: Under gravity and a very small tilt angle, the droplets roll to the edge, are captured by the hydrophilic stripes, and are accelerated and guided to the collection tank 4.

[0071] 3. Capture: The “lip-shaped” structure of the collection tank 4 unconditionally catches all incoming liquid.

[0072] 4. Locking: The hydrophilic tank body and capillary locking edge ensure that the liquid is firmly adsorbed in the tank.

[0073] 5. Outflow: The liquid gathers in the tank and is completely drawn out of the system through the guide port 1.

[0074] Compared with the prior art, the present invention has the following significant advantages: This device provides a highly integrated, passively operated innovative solution for photocatalytic reactions. Its core advantage stems from the novel synergy between capillary self-pumping and photothermal-induced phase transition.

[0075] Achieving continuous reactant supply and extreme mass transfer separation of products: The porous capillary structure continuously and uniformly transports reaction water to the entire catalyst surface through capillary forces, ensuring the wetting of reaction sites. Under illumination, part of the light energy absorbed by the catalyst is used to drive the photocatalytic reaction, while the other part is inevitably converted into photothermal energy, causing the interfacial water film to evaporate in a controlled manner. Taking the photocatalytic hydrogen production process as an example: the generated water vapor and hydrogen products enter the vapor chamber together, realizing the instantaneous stripping of hydrogen from the catalyst surface and its efficient enrichment in the gas phase. This completely solves the core bottleneck of slow hydrogen bubble aggregation and desorption in traditional liquid-phase reactions, greatly improving the mass transfer rate and reaction kinetics.

[0076] To achieve precise temperature control and energy reuse in the reaction system, taking photocatalytic water splitting as an example: Although water splitting is an endothermic process, the photothermal effect of the catalyst causes the system temperature to rise. In this device, interfacial evaporation phase change actively absorbs this excess photothermal energy, effectively preventing local overheating of the catalyst by utilizing the latent heat of phase change, thus stabilizing the reaction temperature within the optimal window. This does not utilize "reaction waste heat," but rather redistributes the input light energy, transforming the harmful risk of overheating into a beneficial driving force for phase change, achieving in-situ energy management.

[0077] Achieving a high degree of system simplification and product pre-enrichment, taking photocatalytic water splitting as an example: the device integrates water transport, photolysis reaction, in-situ separation of the hydrogen and steam mixture, and system temperature control into a passively operating flat-plate unit. The generated hydrogen and steam mixture is characterized by condensation of the steam and direct extraction of the hydrogen, greatly simplifying the complex product collection and separation processes in traditional hydrogen production systems. The system requires only light, operates through capillary and phase change passive physical processes, is structurally reliable, and has extremely low energy consumption.

[0078] The working principle of this device is: 1. Capillary pump self-driven transport: The reaction liquid 9 is first stored in the storage chamber, and then, under the strong capillary force of the porous reaction core layer 7, it is automatically pumped upward like a wick absorbing oil, reaching the reaction / evaporation zone above without additional power.

[0079] 2. Photocatalytic reaction and interfacial evaporation After the porous reaction core layer 7 is transported to the composite functional layer of the reaction / evaporation zone, the photocatalyst loaded on the porous reaction core layer 7 is uniformly wetted. When the light source shines on the catalyst surface through the high-transmittance glass cover plate 3, a photocatalytic reaction occurs. At the same time, part of the light energy absorbed by the catalyst is converted into heat due to the photothermal effect, which raises the temperature of the extremely thin liquid film in contact with it, inducing local micro-boiling evaporation, instantly carrying the generated gaseous products such as hydrogen into the gas phase, and concentrating the non-volatile reactants in the water at the catalyst interface.

[0080] 3. Steam transmission The mixed steam immediately detaches from the catalyst surface and enters the steam chamber. Because steam diffusion is much faster than liquid diffusion, gaseous products such as hydrogen are instantly "removed" from the reaction sites, completely avoiding product inhibition. The mixed steam rises freely within the steam chamber, flowing towards the cooler glass cover plate 3.

[0081] 4. Product separation and condensation When the mixed vapors come into contact with the inner surface of the temperature-controlled glass cover plate 3, the liquid-phase reactants / products release latent heat of phase change and condense into liquid phases for reflux collection, while non-condensable gases such as hydrogen are enriched. The heat released by condensation is continuously carried away by the cooling system inside the cover plate, thereby maintaining the low temperature of the glass cover plate 3.

[0082] 5. Reflux and Recirculation Cooling droplets adhering to the inner surface of the glass cover plate 3 enter the liquid collection tank 4 under the action of gravity, and are returned to the liquid distribution chamber through the reflux device 8. After mixing with the newly replenished reaction liquid 9, they are pumped again through the capillary core pump to participate in the reaction, forming an internal circulation and greatly reducing the generation of waste liquid.

[0083] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0084] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A planar photocatalytic reaction device based on capillary self-drive and phase change cycle, characterized in that, include: The hollow cavity has a liquid storage chamber at the bottom through a porous reaction core layer (7), and a condensation and light transmission mechanism at the top. The hollow cavity is in a negative pressure environment. The porous reaction core layer (7) includes a catalyst support layer, a photocatalyst, and a capillary structure layer. The catalyst support layer is porous, the capillary structure layer is fixed at the bottom of the catalyst support layer, the photocatalyst is coated on the surface of the catalyst support layer, and the capillary structure layer extends into the storage cavity and is immersed in the reaction liquid (9) stored in the storage cavity. The porous reaction core layer (7) is fixed to the bottom of the hollow cavity by a support structure; Light passes through the condensation and light transmission mechanism and irradiates the catalyst support layer. The reaction liquid (9) moves through the capillary structure layer to the catalyst support layer. The reaction liquid (9) undergoes a photocatalytic reaction through the photocatalyst and light irradiation to generate a steam mixture. The steam mixture enters the upper part of the hollow cavity and contacts the condensation end of the condensation and light transmission mechanism. The liquid phase reactants in the steam mixture condense upon cooling. The gas in the steam mixture is discharged through the outlet (2) connected to the hollow cavity.

2. The planar photocatalytic reaction device based on capillary self-drive and phase change cycle according to claim 1, characterized in that: The condensation and light transmission mechanism includes a glass cover plate (3), which is used for light to pass through. A cover body is coaxially fixed to the outer edge of the glass cover plate (3). A coolant tank is coaxially arranged on the cover body. Coolant (5) flows in the coolant tank. The coolant (5) is heat exchanged with the edge of the glass cover plate (3). The cover is also provided with a liquid collection tank (4), which is located in the hollow cavity, and the liquid inlet end of the liquid collection tank (4) is connected to the bottom edge of the glass cover plate (3).

3. The planar photocatalytic reaction device based on capillary self-drive and phase change cycle according to claim 1, characterized in that: The support structure includes multiple support columns (6), the bottom of which is fixed to the bottom wall of the liquid storage cavity; The porous reaction core layer (7) is fixed on the plurality of support columns (6).

4. The planar photocatalytic reaction device based on capillary self-drive and phase change cycle according to claim 1, characterized in that: The top of the hollow cavity is connected to an air outlet (2).

5. A planar photocatalytic reaction device based on capillary self-drive and phase change cycle according to claim 2, characterized in that: The liquid collection tank (4) is connected to a flow guide (1).

6. The planar photocatalytic reaction device based on capillary self-drive and phase change cycle according to claim 1, characterized in that: The liquid storage chamber is connected to a liquid inlet (10).

7. A planar photocatalytic reaction device based on capillary self-drive and phase change cycle according to claim 5, characterized in that: The outlet end of the guide port (1) is connected to the inlet end of the reflux device (8), and the outlet end of the reflux device (8) is connected to the storage chamber.

8. A planar photocatalytic reaction device based on capillary self-drive and phase change cycle according to claim 2, characterized in that: The bottom of the glass cover plate (3) is coated with a hydrophobic layer, and the glass cover plate (3) is provided with multiple hydrophilic stripes, which are arranged radially from the center at the bottom of the glass cover plate (3).

9. A planar photocatalytic reaction device based on capillary self-drive and phase change cycle according to claim 3, characterized in that: The support column (6) is made of either copper or aluminum.

Images