Microwave reaction device for preparing micro-nano material by utilizing waveguide

Abstract

The utility model relates to a microwave reaction device for preparing a micro-nano material by utilizing waveguides. The device comprises a microwave source, a transmission waveguide, a reaction waveguide and a reaction container, the microwave source is used for generating microwaves; the transmission waveguide is arranged on one side of the microwave source and is used for transmitting microwaves to the reaction waveguide; the reaction waveguide is arranged on the other side of the transmission waveguide, and a wave-transparent partition plate is arranged between the reaction waveguide and the transmission waveguide; the reaction container is a concave box body, the top of the reaction container is open, and the notch of the reaction container faces one side of the microwave source; according to the microwave reaction device, the reaction container is arranged at the set position in the reaction waveguide for microwave heating, so that the heating uniformity of a sample can be improved, batch homogeneous preparation of target products is realized, a microwave heating system is greatly simplified, the equipment manufacturing cost is saved, and meanwhile, the energy consumption is reduced.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a microwave reaction device for preparing micro and nanomaterials using waveguides. Background Technology

[0002] Microwave heating technology, due to its unique heating mechanism and rapid, efficient, energy-saving, and environmentally friendly reaction process, is widely used in food processing, chemical synthesis, and materials preparation. In recent years, microwave heating technology has demonstrated significant advantages in the synthesis of micro and nanomaterials. However, as micro and nanomaterial preparation processes develop towards higher precision and higher throughput, the technical bottlenecks exposed in existing microwave reaction systems regarding heating uniformity control are becoming increasingly prominent, severely restricting the application of this technology in large-scale industrial production.

[0003] In existing technologies, the simplest way to improve the uniformity of microwave heating is to add a rotating device to ensure that the sample being heated is uniformly irradiated by microwaves. Alternatively, the uniformity of the microwave field can be improved by adding multiple microwave sources or using a frequency conversion microwave system. Furthermore, the heating uniformity can be improved by designing the structure of the reaction cavity. However, these methods all neglect the interaction between the microwaves and the sample being heated, failing to fundamentally improve heating uniformity. Therefore, the reaction cavity structure design is complex, requiring the introduction of multiple microwave sources or additional sample rotation modules, increasing equipment costs and energy consumption. Especially for special rapid reaction processes and extreme reaction conditions, existing microwave reaction systems cannot meet the needs of large-scale production. Utility Model Content

[0004] To address at least one of the problems in the prior art, the purpose of this invention is to provide a microwave reaction device for preparing micro / nano materials using waveguides. The device uses a concave reaction container to fill the sample raw materials and places the reaction container at a predetermined position within the reaction waveguide. This not only improves the uniformity of sample heating and achieves batch homogeneous preparation of the target product, but also greatly simplifies the microwave heating system, saves equipment manufacturing costs, and reduces energy consumption.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A microwave reaction device for preparing micro / nano materials using waveguides, comprising:

[0007] A microwave source, used to generate microwaves;

[0008] A transmission waveguide is disposed on one side of the microwave source to transmit microwaves to the reactive waveguide;

[0009] A reactive waveguide is disposed on the other side of the transmission waveguide, and a wave-transmitting septum is disposed between the reactive waveguide and the transmission waveguide;

[0010] The reaction container is a U-shaped box with an opening at the top, and the opening of the reaction container faces the microwave source.

[0011] Preferably, the outer contour of the reaction vessel has a length of A along the X-axis, a width of B along the Y-axis, and a height of E along the Z-axis. One side has a U-shaped protrusion with a length of C along the X-axis and a width of D along the Y-axis. The X-axis is horizontally perpendicular to the waveguide transmission direction, the Y-axis is the waveguide transmission direction, and the Z-axis is the opposite direction of the extension of the groove in the reaction vessel. X, Y, and Z are mutually perpendicular. The reaction waveguide in the microwave reaction device containing the reaction vessel has a long side length of a and a short side length of b, where A = (0.8~1)a, 2C <B<0.5A,C=D=(0.15~0.25)A,E=(0.6~1)b。

[0012] Preferably, it further includes:

[0013] A tail-end cutoff baffle is disposed at the tail end of the reactive waveguide to reflect the microwaves, causing them to form a standing wave within the reactive waveguide.

[0014] Preferably, the reaction vessel is a quartz glass vessel.

[0015] Preferably, the wave-transparent partition is a quartz glass plate.

[0016] Preferably, the wall thickness of the reaction vessel is no more than 5 mm.

[0017] Preferably, the geometric center of the reaction vessel is on the centerline of the reaction waveguide, and the distance between the geometric center of the reaction vessel and the tail-end cutoff baffle is ≤ , λ is the waveguide wavelength.

[0018] Preferably, the distance between the geometric center of the reaction vessel and the tail-end shut-off baffle is... or .

[0019] Preferably, the sidewall of the reactive waveguide is provided with an air inlet and an air outlet, the air inlet being used to connect to an inert gas supply device, and the air outlet being used to connect to a gas processing device.

[0020] Preferably, the sidewall of the reactive waveguide is provided with an observation window.

[0021] This utility model has the following advantages due to the adoption of the above technical solution:

[0022] The microwave reaction device for preparing micro and nano materials using waveguides provided by this utility model uses a concave reaction container to fill the sample raw materials and places the reaction container at a predetermined position within the reaction waveguide. This improves the uniformity of sample heating, enables the batch homogeneous preparation of target products, greatly simplifies the microwave heating system, saves equipment manufacturing costs, and reduces energy consumption. Attached Figure Description

[0023] Figure 1 This is a top view schematic diagram of a microwave reaction device for preparing micro / nano materials using waveguides, provided in an embodiment of this utility model.

[0024] Figure 2 This is a front view schematic diagram of a microwave reaction device for preparing micro / nano materials using waveguides, provided in an embodiment of this utility model.

[0025] Figure 3 This is a three-dimensional schematic diagram of the reaction vessel provided in this embodiment of the present invention.

[0026] Figure 4 This is a top view schematic diagram of the reaction vessel provided in this embodiment of the present invention.

[0027] Figure 5 This is a rear view schematic diagram of the reaction vessel provided in this embodiment of the present invention.

[0028] Figure 6 This is an interface diagram showing the electric field intensity distribution within the reactive waveguide under 25kW no-load conditions provided in this embodiment of the present invention.

[0029] Figure 7 This is a diagram showing the effect of heating the reaction vessel provided in this embodiment of the present invention.

[0030] Marked in the attached diagram:

[0031] 1 is the microwave source, 2 is the transmission waveguide, 3 is the reaction waveguide, 301 is the air inlet, 302 is the air outlet, 303 is the observation window, 4 is the reaction container, 5 is the wave-transparent baffle, 6 is the tail-end cutoff baffle, 7 is the power detection module, and 8 is the impedance adjustment unit. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0033] In the description of this utility model, it should be noted that the terms "upper", "lower", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the system or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0034] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "assembly," "setup," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0035] This invention provides a microwave reaction device for preparing micro and nano materials using waveguides. The device uses a concave reaction container to fill the sample raw materials and places the reaction container at a predetermined position within the reaction waveguide. This not only improves the uniformity of sample heating and achieves batch homogeneous preparation of the target product, but also greatly simplifies the microwave heating system, saves equipment manufacturing costs, and reduces energy consumption.

[0036] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0037] Example 1

[0038] Please refer to the reference. Figures 1 to 5 This embodiment provides a microwave reaction device for preparing micro and nano materials using waveguides, including a microwave source 1, a transmission waveguide 2, a reaction waveguide 3, and a reaction container 4;

[0039] Microwave source 1 is used to generate microwaves;

[0040] Transmission waveguide 2 is located on one side of microwave source 1 to transmit microwaves to reactive waveguide 3;

[0041] The reactive waveguide 3 is located on the other side of the transmission waveguide 2, and a wave-transmitting partition 5 is provided between the reactive waveguide 3 and the transmission waveguide 2.

[0042] The reaction vessel 4 is a U-shaped box with an opening at the top, and the opening of the reaction vessel 4 faces the microwave source 1.

[0043] In practical applications, microwave source 1 is used to generate microwaves and can be set to different operating frequencies. Microwave source 1 can adopt existing technology. Transmission waveguide 2 can adopt the existing standard BJ9 type rectangular waveguide. The rectangular waveguide is a metal rectangular cylinder that is hollow inside and at both ends. The cross-section of the reaction waveguide 3 is the same as the cross-sectional dimensions of the transmission waveguide 2, and the length of the reaction waveguide 3 is approximately 2... The length of the waveguide (waveguide wavelength). Specifically, the reactive waveguide 3 can be improved based on the existing standard BJ9 type rectangular waveguide, with a cross-sectional dimension of 247.65*123.82mm and a total length of 880mm.

[0044] In this embodiment, the outer contour of the reaction vessel 4 has a length of A along the X-axis, a width of B along the Y-axis, and a height of E along the Z-axis. The concave protrusion on one side has a length of C along the X-axis and a width of D along the Y-axis. The X-axis is horizontally perpendicular to the waveguide transmission direction, the Y-axis is the waveguide transmission direction, and the Z-axis is the opposite direction of the extension of the groove in the reaction vessel 4. X, Y, and Z are mutually perpendicular. The reaction waveguide 3 in the microwave reaction device containing the reaction vessel 4 has a long side length of a and a short side length of b, where A = (0.8~1)a, 2C <B<0.5A,C=D=(0.15~0.25)A,E=(0.6~1)b。

[0045] In practical applications, reaction vessel 4 is used to fill raw materials. It is made of heat-resistant quartz glass and machined by CNC. Reaction vessel 4 is a quartz glass container with an overall U-shaped shape and its opening facing upwards. The wall thickness of reaction vessel 4 is no more than 5 mm, and can specifically be 3 mm.

[0046] In this embodiment, the microwave reaction device further includes a tail-end cutoff baffle 6, which is disposed at the tail end of the reaction waveguide 3 and is bolted to the end face of the reaction waveguide 3. The tail-end cutoff baffle 6 is used to reflect microwaves, causing them to form a standing wave within the reaction waveguide 3, thereby effectively concentrating the microwave field strength.

[0047] In this embodiment, the wave-transparent partition 5 is a quartz glass plate, but it can also be made of other wave-transparent materials, such as alumina. The wave-transparent partition 5 isolates the transmission waveguide 2 from the reaction waveguide 3, preventing gas in the reaction waveguide 3 from entering the transmission waveguide 2.

[0048] In this embodiment, the reaction vessel 4 is disposed within the reaction waveguide 3, the geometric center of the reaction vessel 4 is on the centerline of the reaction waveguide 3, and the distance between the geometric center of the reaction vessel 4 and the tail-end cutoff baffle 6 is ≤ , The wavelength is defined as the waveguide wavelength. Within this range, heating the raw materials in reaction vessel 4 can improve the uniformity of sample heating. During operation, the notch of reaction vessel 1 faces the incident microwave, meaning the notch of reaction vessel 4 is perpendicular to the microwave source 1.

[0049] In practical applications, when the microwave source 1 operates at a frequency of 915 MHz, the transmission waveguide 2 is a standard BJ9 type waveguide, and the reaction waveguide 3 is an improved version of the standard BJ9 type waveguide. The raw materials are filled into the reaction container 4 through an opening, and then the reaction container 4 is placed at the designated position on the reaction waveguide 3 of the microwave reaction apparatus. The raw materials inside are then heated by microwaves. Please refer to the reference... Figure 6 The placement of reaction vessel 4 is guided by the electric field strength within reaction waveguide 3, and reaction vessel 4 can be placed at the optimal location for field strength distribution; when the distance between the geometric center of reaction vessel 4 and the tail-end cutoff baffle 6 is... or When λg is the waveguide wavelength, uniform heating over the entire area can be achieved. Please refer to [reference needed]. Figure 7 The color difference represents the heating uniformity, indicating that reaction vessel 4 can achieve uniform heating over the entire area. Reaction vessel 4 can also be scaled up proportionally for use in different types of waveguides.

[0050] In this embodiment, an air inlet 301 and an air outlet 302 are provided on the side wall of the reactive waveguide 3. The air inlet 301 is used to connect to an inert gas supply device, and the air outlet 302 is used to connect to a gas processing device.

[0051] Specifically, the inlet 301 and outlet 302 can be located on the sidewalls at both ends of the reaction waveguide 3. The raw materials in the reaction vessel 4 should ideally react in an inert gas environment. The inlet 301 provides the necessary inert atmosphere or reaction atmosphere conditions, while the outlet 302 discharges waste for centralized treatment. The placement of the inlet 301 and outlet 302, the selection of gas types, and the adjustment of flow rates can be flexibly adjusted according to experimental requirements.

[0052] In this embodiment, an observation window 303 is provided on the sidewall of the reactive waveguide 3.

[0053] Specifically, the distance from the sidewall of the reactive waveguide 3 to the tail baffle is 0.5. An observation window 303 with a diameter of 60 mm is provided at the location. The observation window 303 is equipped with transparent quartz glass. The reaction vessel 4 can be observed through the observation window 303 to observe the reaction process of the raw materials inside the reaction vessel 4.

[0054] The microwave reaction apparatus for preparing micro and nanomaterials using waveguides in this embodiment is used to prepare micro and nanomaterials, taking the microwave-assisted synthesis of AL2O3-graphene as a conductive filler as an example.

[0055] The dimensions of the reaction vessel 4 are: A=206mm, B=90mm, C=D=40mm, E=123mm. The initial power of the microwave source 1 is set to 6kW. Under no-load conditions, the reflected power reading is observed through the power detection module 7. The impedance adjustment unit 8 is adjusted to the minimum reflected power. Both the impedance adjustment unit 8 and the power detection module 7 are located on the transmission waveguide 2, which is existing technology. The geometric center of the reaction vessel 4, which is fully loaded with a mixture of graphene oxide and Al2O3 microspheres, is placed at a distance of 0.25λg (110mm) from the tail-end cutoff baffle 6. The connecting bolts between the tail-end cutoff baffle 6 and the reaction waveguide 3 are tightened. The inlet 301 is connected to the high-purity argon gas pipeline, and the outlet 302 is connected to the tail gas pipeline. Before the microwave is turned on, the high-purity argon gas supply equipment is continuously purged at a flow rate of 10L / min for 5 minutes to completely remove the air from the reaction waveguide 3. Then the flow rate is set to 3L / min. The microwave power of microwave source 1 was set to 15kW, and the reaction time was set to 10s. During the reaction, the mixed powder exhibited a rapid change in glow color within 0 to 2s, transitioning from dark red to bright red to bright yellow, and then remaining bright yellow. After the reaction, the current flow rate was maintained for 5 minutes. 45 Raman spectral sampling points of the reaction products were located at 1350 cm⁻¹. -1 Located at 1580cm -1 The peak intensity ratio at the point is 0.09~0.13, which indicates that the graphene oxide was uniformly and with high quality reduced to graphene. Compared with pure epoxy resin, the thermal conductivity of the composite material filled with 50 vol% AL2O3 / graphene is increased by 8 times.

[0056] Another example of using the microwave reaction apparatus of this embodiment to prepare micro and nano materials is to prepare micro and nano materials, and microwave-assisted synthesis of TiO2-graphene for use as a photocatalyst.

[0057] The dimensions of reaction vessel 4 are: A=240mm, B=110mm, C=D=50mm, E=90mm. A three-dimensional network structure mixture of graphene oxide and TiO2 is filled into reaction vessel 4. The geometric center of reaction vessel 4 is placed 0.75λg before the tail-end cutoff baffle 6. The inlet 301 is connected to a high-purity nitrogen pipeline, and the outlet 302 is connected to the tail gas pipeline. Before microwave activation, a high-purity nitrogen device is used to continuously purge at a flow rate of 10L / min for 5 minutes to completely remove air from the reaction waveguide 3. The flow rate is then set to 3L / min. The microwave power of microwave source 1 is set to 8kW, and the reaction time is set to 20s. During the reaction, the glow color of the mixture in reaction vessel 4 gradually changes from dark red to red. After the reaction, the current flow rate is maintained for 5 minutes. The Raman spectrum characterizes the defect density of graphene at 1350cm². -1 Located at 1580cm -1The peak intensity ratio at the point decreased from the initial 1.13 to 0.16, indicating that the defects in graphene oxide were largely repaired. Compared with pure TiO2, the catalytic activity of the reaction product was significantly improved. After three photocatalytic degradations, the degradation rate remained above 96% after 2 hours.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A microwave reaction device for preparing micro / nano materials using waveguides, characterized in that, include: A microwave source, used to generate microwaves; A transmission waveguide is disposed on one side of the microwave source to transmit microwaves to the reactive waveguide; A reactive waveguide is disposed on the other side of the transmission waveguide, and a wave-transmitting septum is disposed between the reactive waveguide and the transmission waveguide; The reaction container is a U-shaped box with an opening at the top, and the opening of the reaction container faces the microwave source.

2. The microwave reaction device for preparing micro / nano materials using waveguides according to claim 1, characterized in that, The outer contour of the reaction vessel has a length of A along the X-axis, a width of B along the Y-axis, and a height of E along the Z-axis. A U-shaped protrusion on one side has a length of C along the X-axis and a width of D along the Y-axis. The X-axis is horizontally perpendicular to the waveguide transmission direction, the Y-axis is the waveguide transmission direction, and the Z-axis is the opposite direction of the extension of the groove in the reaction vessel. X, Y, and Z are mutually perpendicular. The reaction waveguide in the microwave reaction device containing the reaction vessel has a long side length of a and a short side length of b, where A = (0.8~1)a, 2C <B<0.5A,C=D=(0.15~0.25)A,E=(0.6~1)b。 3. The microwave reaction device for preparing micro / nano materials using waveguides according to claim 1, characterized in that, Also includes: A tail-end cutoff baffle is disposed at the tail end of the reactive waveguide to reflect the microwaves, causing them to form a standing wave within the reactive waveguide.

4. The microwave reaction device for preparing micro / nano materials using waveguides according to claim 1, characterized in that, The reaction vessel is a quartz glass container.

5. The microwave reaction device for preparing micro / nano materials using waveguides according to claim 1, characterized in that, The wave-transparent partition is a quartz glass plate.

6. The microwave reaction device for preparing micro / nano materials using waveguides according to claim 1, characterized in that, The wall thickness of the reaction vessel shall not exceed 5 mm.

7. The microwave reaction device for preparing micro / nano materials using waveguides according to claim 3, characterized in that, The geometric center of the reaction vessel is on the centerline of the reaction waveguide, and the distance between the geometric center of the reaction vessel and the tail-end cutoff baffle is ≤ , λ is the waveguide wavelength.

8. The microwave reaction device for preparing micro / nano materials using waveguides according to claim 7, characterized in that, The distance between the geometric center of the reaction vessel and the tail-end shut-off baffle is or .

9. The microwave reaction device for preparing micro / nano materials using waveguides according to claim 1, characterized in that, The sidewall of the reactive waveguide is provided with an air inlet and an air outlet. The air inlet is used to connect to an inert gas supply device, and the air outlet is used to connect to a gas processing device.

10. The microwave reaction device for preparing micro / nano materials using waveguides according to claim 1, characterized in that, The reactive waveguide has an observation window on its sidewall.

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