Photo-thermal catalysis device for controlling and enhancing incoming light flux
By introducing light guide elements into the photothermal catalytic reactor, the light of the light source is concentratedly transmitted to the reactor, and the problem of low efficiency of light energy and thermal energy utilization in the prior art is solved, and efficient photothermal synergistic catalysis is achieved.
Patent Information
- Application Number
- CN202411723662.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2025-03-04
AI Technical Summary
Existing photothermal catalytic reactors are difficult to take into account the high-temperature heating effect and the highest illumination intensity close to the near light source, resulting in low efficiency in both light and heat energy.
A light guide element is introduced in the photothermal catalytic reactor, through which the light guide element is concentratedly transmitted to the reactor, maximizing the irradiation flux received by the sample, and a light path channel is reserved in the design of the heating module to avoid light transmission losses.
By introducing light guide elements, the light utilization rate and reaction rate in the reactor are significantly increased, the high-temperature heating effect is maintained, and the light loss and thermal damage to the light source by the heating module are avoided.
Smart Images
Figure CN119549088A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a photothermal catalytic device for controlling and enhancing incoming light flux, belonging to the technical field of photothermal catalysis. Background Art
[0002] Catalytic reactions are almost present in the entire field of chemical reactions. The use of catalysts can increase the reaction rate without changing the chemical equilibrium. In modern chemical production, catalysts play a pivotal role.
[0003] Photocatalysis and thermocatalysis are two important fields in the discipline of catalysis. Thermocatalysis is a traditional catalytic reaction process that causes chemical reactions by overcoming the activation energy barrier under high temperature conditions. Fixed bed reactors, as one of the common reaction modes, are widely used in thermocatalytic reactions. Under the action of light of a certain wavelength, photocatalysis excites paired electron holes to participate in chemical reactions. Kettle reactors are one of the commonly used devices for photocatalytic reactions. In recent years, studies have found that when light and heat are applied to a part of the catalyst at the same time, there is a synergistic effect, that is, the performance of the catalyst will be higher than the single photocatalytic or thermocatalytic activity. Photothermal catalytic reactions use the synergistic effect of light and heat to promote each other and have important application value. At present, photothermal catalysis can be applied to a variety of reactions, and has been widely studied in Fischer-Tropsch synthesis, carbon dioxide reduction, organic matter degradation, ammonia synthesis, and water decomposition to produce hydrogen.
[0004] There are usually two ways to introduce heat sources for photothermal catalytic reactions: self-heating and auxiliary heating. Self-heating is to use the thermal effect of light through a converging lens to heat the catalyst in a smaller range; auxiliary heating is an external heat source, using a heating module around the reactor to heat the catalyst. Usually, the heat energy obtained by self-heating is limited and can only heat a small range of catalysts. There may be problems such as uneven heat energy distribution and difficulty in accurately controlling the temperature. External heating can more easily obtain a stable heat source.
[0005] In common photothermal catalytic reaction research, in addition to the heat source, it is also necessary to select a light source that matches the reaction. The artificial light sources used in the research and development of photothermal catalytic reactions can be simply divided into ultraviolet bands, visible light bands and infrared bands according to the wavelength. Commonly used light source systems in laboratories include xenon lamps, mercury lamps, LED light sources, etc. Xenon lamps are widely used in photothermal catalytic reactions because they are similar to the solar spectrum and include infrared to ultraviolet bands. Mercury lamps can usually cover the ultraviolet and visible light wavelength ranges and can obtain a large light intensity. LED light sources can make the luminous range cover different bands as needed. In addition, by combining the light source with a filter and a monochromator, monochromatic light can be generated for special photothermal catalytic reaction research. Generally speaking, the luminous intensity near the luminous surface of the artificial light source is higher than the irradiation intensity of sunlight on the ground. For example, a xenon lamp can reach more than ten times that of sunlight. However, when the distance between the irradiated object and the artificial light source increases, the irradiation intensity will drop rapidly.
[0006] In addition, the evaluation of photothermal catalyst performance and the study of reaction mechanisms rely on various characterization instruments and also require suitable reactors. Some photothermal catalytic reactions are carried out in closed containers containing reactants and catalysts (such as reactors, glass containers, etc.), and then the products are extracted for detection; in addition, more and more photothermal catalytic reactors use the same method as fixed bed reactors commonly used in thermal catalysis, fixing the catalyst, allowing the reactants to flow, and the products enter the product detector from one end of the reactor. With the deepening of research on photothermal catalytic reactions, the development and improvement of reactors have become more important.
[0007] The existing photothermal catalytic reactors are mainly aimed at the two types of existing photothermal catalysis, namely self-heating and auxiliary heating, and there are different photothermal reactors for each type. The self-heating reactor mainly introduces a converging lens in the light path from the light source to the catalyst, converges a large area of light source into a very small range, and uses the light source to heat the catalyst. For the photothermal reaction with auxiliary heating, similar to the traditional fixed-bed thermal catalytic reactor, a heating module is usually installed around the reactor to achieve the heating of the reactor. The heating module is equipped with a PID controller (Proportion Integration Differentiation, proportional-integral-differential controller) equipped with a thermocouple to accurately control the temperature, and can also achieve real-time temperature changes according to the reaction requirements.
[0008] For photothermal reactors, especially photothermal reactions that require auxiliary heating. The presence of the heating module will affect light transmission. In order to introduce light to the catalyst, the usual solution is to reserve a light path channel when designing the heating module. The design of the light path channel is determined according to the shape of the device and the requirements of the reaction. Usually, the heating module is in direct contact with the reactor. In order to leave enough space for the heating module and prevent high temperature from damaging the light source, there must be enough distance between the light source and the reactor. However, since the light is not parallel, the farther the distance, the smaller the radiation flux value received within the sample range. This reduces the light utilization rate and reaction rate. In addition, for traditional kettle reactors, the light-transmitting window is usually located at the top of the reactor, and the catalyst is generally located at the bottom of the reactor. There is also a long distance between the window and the catalyst. The radiation flux that is finally irradiated to the sample is lower, and it is difficult to obtain a larger light utilization rate.
[0009] The above shortcomings make it difficult for existing photothermal catalytic reactors to take into account both the high-temperature heating effect and the highest light intensity near the light source. If the irradiation intensity in the reactor is increased by increasing the luminous power of the artificial light source, the cost of the equipment will be greatly increased, which is also a waste of energy. Therefore, how to achieve the maximum simultaneous utilization of light energy and heat energy in the photothermal catalytic reactor is one of the problems currently faced by research. Summary of the invention
[0010] The purpose of the present invention is to solve the shortcomings of the existing photothermal catalytic reactor and provide a photothermal catalytic device for controlling and enhancing the light flux.
[0011] In order to achieve the above-mentioned purpose, the present invention provides a photothermal catalytic device for controlling and enhancing the incoming light flux, including a photothermal catalytic reactor provided with a heating module, a sample table provided in the photothermal catalytic reactor, and a light guiding element for introducing the light source and irradiating the sample table on the light inlet channel of the photothermal catalytic device.
[0012] Preferably, the heating module comprises a temperature controller and a heating element, and the heating element is configured to heat the photothermal catalytic reactor.
[0013] Preferably, the light inlet channel is arranged at one side of the photothermal catalytic reactor and is located above the sample stage, and the light guiding element is arranged in the light inlet channel and contacts the photothermal catalytic reactor.
[0014] Preferably, the light guide element is made of an optically transparent material, including but not limited to quartz glass, inorganic glass, and optical fiber material, etc. The inorganic glass may be borosilicate glass, alkali metal glass, lithium glass, etc., and the optical fiber material may be siloxane, fluoride optical fiber, etc.
[0015] Preferably, the photothermal catalytic reactor is a quartz tube reactor, and the heating element is made of metal, such as a metal heating wire, a heating tube, etc. The heating element can be set as a heating gun or a heating furnace, or the photothermal catalytic reactor can be directly heated by a heating wire or a heating tube.
[0016] Preferably, it also includes a light source, which is arranged above the light-guiding element, the top of which is close to the light source, and the bottom of which is arranged in the light inlet channel and in contact with the photothermal catalytic reactor.
[0017] Preferably, the distance between the light source and the bottom of the light guide element is determined by the length and shape of the light guide element itself. When the light guide element is columnar, the distance between the light source and the bottom of the light guide element may be 100-300 mm.
[0018] Preferably, the shape of the light guide element is set according to the operation of the light source and the photothermal catalytic device, and is usually but not limited to a cylindrical shape. For example, the light guide element may be a quartz column, and the height of the quartz column may be 25 to 200 mm.
[0019] Preferably, a coating (anti-reflection film) is provided on the cylindrical surface of the quartz column to further improve the light transmittance of the interface.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] (1) The device of the present invention is simple and easy to install and disassemble;
[0022] (2) Maximize the irradiation flux received by the sample, and keep the irradiation intensity of the irradiated object close to the luminous flux of the same area of the light source surface after increasing the distance;
[0023] (3) The irradiation flux received by the sample can be controlled. By using light guide elements of different lengths, the irradiation can be controlled to any value below the luminous flux of the same area on the luminous surface of the light source;
[0024] (4) The light source is not damaged by the heat of the heating module and can be operated safely outside the light guide element without light loss;
[0025] (5) Light guide components are easy to obtain, have low manufacturing costs, and have a long service life;
[0026] (6) The applicable temperature range is wide. For conventional materials, the light guide element can work stably at temperatures above 400°C. For materials such as quartz, it remains stable at 800-1000°C, meeting the needs of most photothermal reactions.
[0027] (7) High reliability, not affected by the external environment;
[0028] (8) The device is widely used and is applicable to various types of reactors including but not limited to fixed beds and kettle furnaces. It can be easily made into different shapes and sizes according to different special requirements. It has no special requirements for the reaction and can be applied to various photothermal catalytic reactions. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 It is a cross-sectional view of a photothermal catalytic reactor (based on a fixed bed structure) equipped with a light-guiding element in an embodiment of the present invention.
[0030] Figure 2 It is a schematic diagram of the structure of a cylindrical quartz light guide element.
[0031] Figure 3 The comparative light path diagram from the light source to the sample when the light guide element is set or not.
[0032] Figure 4 (a) Schematic diagram of the implementation of detection method 1: the distance between the light source and the light intensity detector remains fixed and (b) the irradiance detection value after adding light guide elements of different lengths in the light path.
[0033] Figure 5 (a) Schematic diagram of the implementation of detection method 2: adding a light guide element under different distances between the light source and the light intensity detector and (b) comparison of irradiance detection values before and after adding the light guide element.
[0034] Figure 6 It is a schematic diagram of the photothermal catalytic device of the present invention applied to photothermal catalytic water decomposition to produce hydrogen.
[0035] Figure 7 The actual pictures of the photothermal catalytic device are equipped with 50mm (a) and 150mm (b) cylindrical quartz light-guiding elements. DETAILED DESCRIPTION
[0036] In order to make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.
[0037] The present invention relates to an improvement on a common photothermal catalytic reactor in the prior art, introducing a light-guiding element into the light path, reducing the transmission loss in the light path, and maintaining the incoming light flux near the reactor close to the light flux of the same area near the light source while using a heating module to control the high temperature of the reactor, so as to maximize the use of the light source. Before adding the light-guiding element, due to the divergence and rectilinear propagation characteristics of the light emitted by the light source, only the light within a small solid angle range will eventually irradiate the sample to act, and most of the light will irradiate outside the sample area. When the light-guiding element is introduced into the light path, all the light intercepted by the light-guiding element near the light source will be transmitted along the inner wall and the interior to the bottom reactor. This scheme increases the incoming light flux of the photothermal catalytic reactor and improves the luminous utilization rate of the light source without changing the basic structure and light source of the photothermal catalytic reactor, and is suitable for different types of reaction devices. For example, for a kettle reactor, the window at the top is changed to a light-guiding element with a certain length extending from the top inward to the upper end of the catalyst, so that the light can be introduced from the light source into the reactor catalyst, reducing the loss caused by the transmission without the light-guiding element.
[0038] The material used to prepare the light-guiding element must have a large transmittance to ensure that it does not hinder the propagation of light. The refractive index of the material should be greater than 1.2, such as 1.5 for ordinary glass, 1.43 for fluorite, 1.52 for crown glass, 1.55 for quartz, 2.42 for diamond, etc. You can also choose a suitable optical fiber to ensure that the light is transmitted along the inner wall and the interior to minimize the transmission loss; at the same time, the refractive index of the sample is controlled not too high. Too high a refractive index will cause the corresponding material to reflect more light at the incident and exit interfaces, increasing additional light loss to ensure that as much light as possible enters. Because it needs to be adapted to high temperature conditions, the material of the light-guiding element should be able to remain stable at high temperatures, and it is not suitable to use materials with good thermal conductivity to avoid damage to the light source due to high temperature. Specifically, the material that can meet the requirements of transmittance and temperature resistance can be selected in combination with the physical properties of the material and the reaction temperature. The shape of the light-guiding element is generally pre-shaped into a certain shape, which can be roughly cylindrical, and the shape is allowed to be distorted to a certain extent according to the actual position relationship between the reactor and the light source. The surface of the light guide element is divided into the incident surface, the exit surface and the side surface, and the corresponding flatness should reach the optical polishing degree corresponding to the wavelength range of the light source. According to the needs, the cross-section preparation of the element can meet various shape requirements to meet the needs of the reactor.
[0039] The present invention provides a method for maximizing the light flux by setting a light guide element, while maintaining a sufficient distance between the light source and the catalyst. Figure 1As shown, it includes: a light guide element 1, a heating module 2, a quartz reaction tube 3, and a sample stage 4. The present invention adds a light guide element to the original reserved light path channel, and the light originally diffused and transmitted in the air is concentratedly transmitted to the reactor by the light guide element, so as to maximize the light intensity received by the catalyst.
[0040] Example 1: Using a cylindrical light guide element made of quartz material to increase the light flux
[0041] This embodiment provides a cylindrical light guide element made of quartz material, such as Figure 2 As shown, Figure 2 The three-view diagram and the stereogram of the cylindrical light guide element are shown, and 11, 12 and 13 represent the incident surface, the exit surface and the side surface of the light guide element respectively. To illustrate the principle that the present invention can enhance the illumination of the sample, the illumination intensity of the sample under the same light source is compared with and without the light guide element. The light transmission path is shown in FIG. Figure 3 As shown. When there is no light-guiding element in the optical path, when the light emitted by the light source irradiates the catalyst, only the light within the solid angle range of the sample corresponding to the light source takes effect, and the rest of the light is diverged outside the sample; in comparison, after adding a light-guiding element in the optical path, the larger divergence angle emitted by the light source corresponds to the solid angle range of the incident surface of the quartz column relative to the light source. The light enters the quartz column and is transmitted to the sample surface, thereby increasing the light flux. This embodiment uses two different methods to respectively detect the effect of the light-guiding element on the light intensity received by the sample under different conditions. The two detection methods and the results are shown respectively as follows. Figure 4 , Figure 5 shown.
[0042] In this embodiment, the light-guiding element is made of quartz material, which has low cost, high light transmittance and stable properties.
[0043] In this embodiment, the quartz material is processed into a cylindrical shape, and the two ends and the sides are polished to meet the light guiding requirements of the reactor. Figure 2 shown.
[0044] In this embodiment, a 300W xenon lamp with high universality and moderate price is used as the light source, which can simulate the wavelength range of sunlight and has a luminous power of 1475mW / cm 2 .
[0045] In this embodiment, a filter is used to simulate the filtering effect of the atmosphere on sunlight, so as to simulate the attenuation of sunlight under real lighting conditions.
[0046] The test method 1 settings and the results are as follows Figure 4As shown in the figure, in order to leave enough space for the heater in the real reaction device, the distance between the light source and the light intensity detector is fixed at 205mm. In the long optical path between the light source and the light intensity detector, quartz columns of different lengths (25, 50, 100, 150, 200mm) are added to detect the irradiance values respectively. The results show that the irradiance detection value increases with the increase of the quartz column length, which indicates that the quartz column in the optical path can play a role in increasing the light flux received by the reactor. When the length of the quartz column reaches 200mm, the detected irradiance is 1218mW / cm 2 , reaching the irradiance at the light source outlet (1475mW / cm 2 ) is 82.6%; the irradiance without light guide is less than 500mW / cm 2 After adding quartz column light guide elements of different lengths, the detected irradiance is 500-1218mW / cm 2 This result fully demonstrates that the addition of light-guiding elements can reduce the light attenuation during transmission. According to basic optical knowledge, the main loss after adding light-guiding elements is caused by the light being reflected twice by the incident surface (11) and the exit surface (13). This loss can be reduced by a multi-layer coating method. The coating refers to an anti-reflection film (anti-reflection film). Suitable coating materials may be, for example, MgF2, CaF2, Al2O3, SiO2, etc., but are not limited to the above materials; the coating mainly reduces or eliminates the reflected light from optical surfaces such as lenses. The effect of the anti-reflection film is related to the refractive index of the material. It is also necessary to match the films of different materials according to the designed thickness to achieve the effect of anti-reflection and anti-reflection. Different anti-reflection films may work in different light bands. Suitable coating materials can be selected according to actual reaction requirements.
[0047] The settings and results of detection method 2 are as follows Figure 5 As shown in the figure, taking the reactor and the heating module thickness, that is, the distance from the light source to the sample of 100mm, 150mm and 200mm as an example, the irradiance value detected when the light guide element is completely added to the light path is compared with that without the light guide element. The results show that under different distance conditions (100, 150, 200mm), adding a cylindrical light guide element to the light path can effectively improve the detected irradiance value. When there is no light guide element in the light path, the irradiance detection value increases from 802mW / cm to 1000mW / cm when the distance between the light source and the light intensity detector increases from 100mm to 200mm. 2 Down to 476mW / cm 2 , the amplitude will be more than 40%. The irradiance decreases greatly with distance and is much lower than the irradiance at the light source outlet (1475mW / cm 2 ), the proportion is 32%-54%. When there is a light guide element in the light path, the irradiance decreases from 1373mW / cm 2Only dropped to 1218mW / cm 2 The decrease is only 11%, which is much lower than the decrease without light guide element (41%), and relative to the irradiance at the light source outlet (1475mW / cm 2 ) has no obvious loss, the ratio is 83%-93%.
[0048] In summary, the test results of this embodiment clearly show that, compared with direct air transmission, the addition of light-guiding elements in the optical path greatly increases the incoming light flux, basically retains the original irradiation intensity near the light source, and can effectively enhance the light utilization rate.
[0049] Application example 1. Photothermal catalytic water decomposition to produce hydrogen
[0050] A schematic diagram of a photothermal catalytic device equipped with a light-guiding element and its application in photothermal catalytic water decomposition to produce hydrogen is shown in FIG. Figure 6 As shown; Figure 7 a and Figure 7 b is a physical picture of the device equipped with 50mm and 150mm cylindrical quartz light guide elements respectively. In this application example, TiO2 is used as a catalyst to complete the photolysis of water to produce hydrogen under the synergistic effect of light and heating. The reaction uses argon as a carrier gas, and the argon flow rate is controlled at about 10sccm. The reaction raw material liquid water is injected into the gas path using a constant flow pump, and the gas path is heated to vaporize the water. The vaporized water vapor is carried into the reactor by argon gas and decomposed under the action of light and heat on the solid phase catalyst. The flow rate of water is determined according to the flow rate of the carrier gas, which is slightly greater than the flow rate required to meet the saturated water vapor. Product detectors such as gas chromatography and mass spectrometry can be installed downstream of the reactor to complete product evaluation.
[0051] In this application example, high-purity argon (99.999%) was used as the carrier gas, and the carrier gas flow rate was controlled to 10 sccm by a mass flow controller;
[0052] In this application example, a high-pressure constant-flow pump is used to inject liquid water into the gas line, which can inject water into the pipeline at a stable flow rate for a long time;
[0053] In this application example, a quartz tube is used as a reactor. As a high temperature resistant material, quartz is stable and not easy to react with reactants, and has a high light transmittance, which is suitable for photocatalytic reactions.
[0054] In this application example, a metal heating element is used, which can achieve a temperature of 800°C and a heating rate greater than 10°C / min due to its good thermal conductivity;
[0055] In this application example, a 300W xenon lamp is used as the light source, which is easy to assemble and has a high degree of simulation with sunlight;
[0056] The improved photothermal catalytic reactor of the present invention is connected with the gas path device to build a complete photothermal catalytic reaction system, which effectively completes the catalyst evaluation of the water decomposition reaction under photothermal conditions. The xenon lamp light source works normally when the heater is set at 800°C, and there is no obvious temperature rise on the surface. Furthermore, the concept of adding a light guide element in the present invention can play a role in various other photothermal catalytic reaction devices.
[0057] The above description is only a preferred embodiment of the present invention and is not any formal or substantial limitation of the present invention. It should be pointed out that a person skilled in the art can make several improvements and supplements without departing from the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention.
Claims
1. A photothermal catalytic device for controlling and enhancing light flux, comprising a photothermal catalytic reactor provided with a heating module, wherein a sample stage is provided in the photothermal catalytic reactor, characterized in that: The light inlet channel of the photothermal catalytic device is provided with a light-guiding element for guiding the light source and irradiating it onto the sample stage.
2. The photothermal catalytic device according to claim 1, characterized in that: The heating module includes a temperature controller and a heating element, and the heating element is configured to heat the photothermal catalytic reactor.
3. The photothermal catalytic device according to claim 2, characterized in that: The light inlet channel is arranged at one side of the photothermal catalytic reactor and is located above the sample stage. The light guiding element is arranged in the light inlet channel and contacts the photothermal catalytic reactor.
4. The photothermal catalytic device according to claim 1, characterized in that: The light guide element is made of an optically transparent material.
5. The photothermal catalytic device according to claim 1, characterized in that: The photothermal catalytic reactor is a quartz tube reactor, and the heating element is made of metal.
6. The photothermal catalytic device according to claim 1, characterized in that: It also includes a light source, which is arranged above the light-guiding element. The top of the light-guiding element is close to the light source, and the bottom is arranged in the light inlet channel and in contact with the photothermal catalytic reactor.
7. The photothermal catalytic device according to claim 6, characterized in that: The distance between the light source and the bottom of the light guide element is determined by the length and shape of the light guide element itself.
8. The photothermal catalytic device according to claim 7, characterized in that: The shape of the light guide element is set according to the operation of the light source and the photothermal catalytic device.
9. The photothermal catalytic device according to claim 8, characterized in that: A coating is provided on the cylindrical surface of the quartz column to further improve the light transmittance of the interface.