Integrated apparatus and method for treating VOCs by adsorption-desorption-in-situ catalytic oxidation

Abstract

The application belongs to the technical field of waste gas treatment, and discloses a VOCs adsorption-desorption-in-situ catalytic oxidation integrated treatment device and treatment method. The device is sequentially provided with an air inlet, an airflow rectification and distribution structure, a first adsorption catalytic reaction zone, a second adsorption catalytic reaction zone and a terminal catalytic oxidation reaction zone from one side to the other side. The airflow rectification and distribution structure is arranged perpendicularly to the direction of the waste gas flow and comprises a plurality of airflow adjusting vanes arranged side by side. Each airflow adjusting vane comprises a vane body and a vane rotating shaft. The vane body is arranged on the vane rotating shaft. The end of the vane rotating shaft is connected with a driving motor through a coupling. The rotation angle of each airflow adjusting vane is adjusted to rectify and distribute the airflow along the cross-sectional direction. The microwave feeding device is arranged outside each adsorption-catalytic reaction zone, and the filler is arranged inside each adsorption-catalytic reaction zone. The adsorption catalyst is attached to the filler. The adsorption, desorption and in-situ catalytic oxidation of VOCs in the waste gas can be realized.

Description

Technical Field

[0001] This invention belongs to the field of volatile organic compound (VOCs) waste gas treatment technology, specifically relating to an integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device and method. It is particularly suitable for the efficient adsorption, rapid desorption, and in-situ catalytic degradation of VOCs under conditions of large air volume and fluctuating concentrations. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] The current mainstream treatment technology for large-volume, low-concentration VOCs waste gas is to use zeolite rotor adsorption concentration followed by catalytic combustion. This mainly includes the following steps: purifying large-volume, low-concentration VOCs waste gas using zeolite rotor adsorption; purging the saturated zeolite rotor with hot air to desorb the adsorbed VOCs, forming high-concentration, low-volume concentrated waste gas; and then heating the concentrated waste gas for catalytic combustion.

[0004] This treatment technology has the following problems: 1) Unsaturated VOCs such as styrene and acrylates are prone to polymerization and pore blockage during hot air desorption, leading to rapid deactivation of the adsorbent and a significantly shortened lifespan; 2) Mainstream Pt / Pd precious metal catalysts are easily deactivated by poisoning from sulfur, chlorine, and heavy metals in the waste gas, resulting in poor stability and high replacement costs; 3) The dynamic rotation structure of the rotor is not adaptable to fluctuations in air volume and concentration, and is prone to safety hazards such as VOC escape and local overheating; 4) The system consists of multiple units such as adsorption, desorption, catalysis, and heat exchange, making the equipment complex, occupying a large area, consuming high energy, and requiring cumbersome operation and maintenance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device and method. The present invention can achieve continuous uninterrupted operation of a single device, precise temperature control in zones, immediate degradation upon desorption, and wide operating condition adaptability. It can significantly simplify the system structure, reduce energy consumption and operation and maintenance costs, improve the catalyst's resistance to poisoning and polymerization, and has good operational safety.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides an integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device, comprising, from one side to the other, an air inlet, an airflow rectification and distribution structure, a first adsorption catalytic reaction zone, a second adsorption catalytic reaction zone, and a terminal catalytic oxidation reaction zone, wherein... The airflow rectification and distribution structure is set perpendicular to the direction of the exhaust airflow and includes several airflow regulating blades arranged in parallel. Each airflow regulating blade includes a blade body and a blade shaft. The blade body is set on the blade shaft, and the end of the blade shaft is connected to the drive motor through a coupling. By adjusting the rotation angle of each airflow regulating blade, the airflow is rectified and distributed along the cross-sectional direction. Each adsorption-catalysis reaction zone is equipped with a microwave feed device on its exterior and packing material inside, with adsorption catalyst attached to the packing material.

[0007] Secondly, the present invention provides an integrated treatment method for VOCs adsorption-desorption-in-situ catalytic oxidation, which is carried out using the aforementioned integrated treatment device and includes the following steps: When the VOCs concentration in the waste gas to be treated is higher than the emission standard limit, the waste gas is introduced from the inlet and enters the adsorption-catalytic reaction zone for adsorption under the rectification and distribution of the airflow rectification and distribution structure. The gas purified by adsorption is discharged from the outlet. When the concentration of VOCs in the exhaust gas exceeds the set value, the adsorption catalyst regeneration process is activated, and the inlet flow rate of the exhaust gas is reduced to serve as the exhaust gas carrier gas. First, start the microwave feed device of the terminal catalytic oxidation reaction zone to heat it to the catalytic decomposition temperature of VOCs and above; then turn on the microwave feed device of the first adsorption catalytic reaction zone and / or the second adsorption catalytic reaction zone to heat the inside, so that the VOCs adsorbed on the adsorption catalyst are desorbed and catalytically degraded in situ. At the same time, the waste gas carrier gas carries out the degraded gas, and the VOCs in the waste gas carrier gas are catalytically degraded by the adsorption catalyst. During the regeneration process, the airflow rectification and distribution structure distributes the waste gas carrier gas in the cross-sectional direction, so that the temperature of the adsorbed catalyst is evenly distributed in the cross-sectional direction.

[0008] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows: In this invention, the airflow rectification and distribution structure consists of several airflow regulating blades arranged in parallel, blade shafts, and drive motors. By adjusting the rotation angle of each airflow regulating blade, the width of the airflow channel is changed, so that the exhaust gas, which may have uneven flow velocity and turbulent direction, is regulated in the cross-sectional direction, forming a stable and uniform airflow. This avoids uneven load in the subsequent treatment area due to airflow turbulence, thereby improving treatment efficiency and effect.

[0009] Based on the processing capacity and requirements of different adsorption and catalytic reaction zones, the waste gas flow rate is rationally allocated to ensure that each zone receives an appropriate amount of waste gas for treatment, thereby achieving optimized operation of the entire device. The drive motor drives the blade shaft to rotate via a coupling, providing power support for blade angle adjustment and ensuring the realization of rectification and distribution functions.

[0010] The terminal catalytic oxidation reaction zone performs final catalytic oxidation treatment on any small amount of VOCs that may still escape after being treated in the first two adsorption catalytic reaction zones, preventing VOCs from escaping and ensuring that the exhaust gas can meet emission standards. Attached Figure Description

[0011] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0012] Figure 1 This is a schematic diagram of the overall structure of the integrated VOCs treatment device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the internal structure of the integrated VOCs treatment device according to an embodiment of the present invention; Figure 3 A schematic diagram of a glass fiber corrugated structured carrier. Figure 4 This is a schematic diagram of an airflow distribution device. Figure 5 This is a schematic diagram of the airflow regulating blade structure; Figure 6 This is a schematic diagram of the adsorption-catalysis reaction zone structure; Figure 7 This is a schematic diagram of the structure of the terminal catalytic oxidation reaction zone; Figure 8 This is a schematic diagram of the microwave feed and temperature measurement point distribution. Figure 9 This is a schematic diagram of the microstructure of a core-shell structured adsorption-catalysis composite material, in which: a molecular sieve adsorption core is used for selective adsorption, and a porous metal oxide catalytic shell is used to achieve microwave-responsive heating and catalytic oxidation, illustrating the migration pathway of VOC molecules (illustrated). Figure 10 For x% Fe 0.85 -Mn 0.1 -Ce 0.05 / UB50 adsorption catalyst, a comparison chart of the catalytic performance of the adsorption catalyst when the loading value x is different; Figure 11 For x% Fe 0.85 -Mn 0.1 -Ce 0.05 @UB50 catalytic stability test comparison chart; Figure 12The graph shows the dielectric constant performance of x%Fe-Mn-Ce / UB50 adsorption catalyst when x represents the different loading values ​​of Fe-Mn-Ce catalyst on UB50. Here, a is the real part of the dielectric constant, reflecting the degree of dielectric polarization; a larger value indicates stronger polarization. b is the imaginary part of the dielectric constant, also called the dielectric loss coefficient, representing the portion of energy from the alternating electric field in the dielectric that is converted into heat; a larger imaginary part indicates greater material loss and stronger heat generation. c is the loss tangent tanδ = ε″ / ε′, representing the ratio of heating rate to the ease of polarization. Figure 13 To adsorb 20% Fe after toluene saturation 0.85 -Mn 0.1 -Ce 0.05 @UB50 (0.2g) was directly subjected to microwave irradiation. The trend of CO2 concentration change in the gas after the reaction. Figure 14 The trend of catalytic performance of xy-GO / MnO2@UB50 adsorption catalysts (where x is the loading of MnO2 catalyst on UB50 and y is the percentage of GO in MnO2 catalyst) prepared by loading GO / MnO2 catalyst with different mass percentages onto UB50 adsorbents as catalytic oxidation temperature. Figure 15 The absorption characteristics parameters of different xy-GO / MnO2@UB50 adsorption catalysts are given, where a is the real part of the dielectric constant, reflecting the degree of dielectric polarization; the larger the value, the stronger the polarization. b is the imaginary part of the dielectric constant, also called the dielectric loss coefficient, which represents the part of the energy of the alternating electric field in the dielectric that is converted into heat; the larger the imaginary part value, the greater the material loss and the stronger the heat generation. c is the loss tangent tanδ = ε″ / ε′, which represents the ratio of heating rate to polarization difficulty. Figure 16 To load xy-GO / MnO2@UB50 onto a structured support, the adsorption curve (a) of toluene on the prepared monolithic adsorption catalyst and the desorption-degradation curve (b) of toluene under microwave irradiation are shown.

[0013] Wherein: 1-Air inlet; 2-Airflow rectification and distribution structure; 21-Airflow regulating blade; 211-Blade body; 212-Blade shaft; 22-Coupling; 23-Drive motor; 24-Motor bracket; 3-First adsorption-catalytic reaction zone; 4-Second adsorption-catalytic reaction zone; 41-First microwave feed device; 42-Packaging material; 5-End-stage catalytic oxidation reaction zone; 51-Second microwave feed device; 52-Cylindrical catalytic packing; 6-Gas outlet; 7-Microwave generator; 8-Reactor shell; 9-Insulation layer; 10-Gap; 11-VOCs concentration detector; 12-Glass fiber thermometer; 13-Temperature sensing element; 14-PLC control unit. Detailed Implementation

[0014] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0015] In a first aspect, the present invention provides an integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device, comprising, from one side to the other, an air inlet, an airflow rectification and distribution structure, a first adsorption catalytic reaction zone, a second adsorption catalytic reaction zone, and a terminal catalytic oxidation reaction zone, wherein... The airflow rectification and distribution structure is set perpendicular to the direction of the waste gas flow and includes several airflow regulating blades arranged in parallel. Each airflow regulating blade includes a blade body and a blade shaft. The blade body is set on the blade shaft, and the end of the blade shaft is connected to the drive motor through a coupling. By adjusting the rotation angle of each airflow regulating blade, the width of the airflow channel is adjusted, and the airflow is rectified and distributed along the cross-sectional direction. Each adsorption-catalysis reaction zone is equipped with a microwave feed device on its exterior and packing material inside, with adsorption catalyst attached to the packing material.

[0016] The airflow rectification and distribution structure consists of several airflow regulating blades arranged in parallel, blade shafts, and drive motors. By adjusting the rotation angle of each airflow regulating blade, the width of the airflow channel is changed, so that the exhaust gas, which may have uneven flow velocity and turbulent direction, is regulated in the cross-sectional direction, forming a stable and uniform airflow. This avoids uneven load in the subsequent treatment area due to airflow turbulence, thereby improving treatment efficiency and effect.

[0017] Based on the processing capacity and requirements of different adsorption and catalytic reaction zones, the waste gas flow rate is rationally allocated to ensure that each zone receives an appropriate amount of waste gas for treatment, thereby achieving optimized operation of the entire device. The drive motor drives the blade shaft to rotate via a coupling, providing power support for blade angle adjustment and ensuring the realization of rectification and distribution functions.

[0018] The adsorption catalysts on the packing material in both the first and second adsorption catalytic reaction zones have a large specific surface area and abundant pore structure, enabling them to efficiently adsorb VOCs molecules in the waste gas and transfer them from the gas phase to the solid phase, thus achieving preliminary purification of the waste gas. The arrangement of two adsorption catalytic reaction zones increases the contact time and contact area between the waste gas and the adsorption catalyst, improving adsorption efficiency and ensuring that more VOCs are adsorbed and removed.

[0019] Under the microwave heating provided by the microwave feed device, VOCs adsorbed by the adsorption catalyst are desorbed, and the adsorption catalyst is activated, promoting the catalytic oxidation reaction of the desorbed VOC molecules. Microwave heating has the advantages of rapid heating rate, uniform heating, and selective heating. It can achieve selective heating of the catalyst and efficient oxidation and decomposition of VOCs at a relatively low overall temperature, converting them into harmless substances such as CO2 and H2O, thus achieving the purpose of deep purification of waste gas.

[0020] The terminal catalytic oxidation reaction zone performs final catalytic oxidation treatment on any small amount of VOCs that may still escape after being treated in the first two adsorption catalytic reaction zones, preventing VOCs from escaping and ensuring that the exhaust gas can meet emission standards.

[0021] In some embodiments, the blade pivot is disposed on the central axis of the blade body.

[0022] When the shaft is located on the central axis of the blade, the centrifugal force, airflow impact force, and other external forces acting on the blade during rotation can be relatively evenly distributed on both sides of the shaft. This uniform stress state can effectively reduce local stress concentration on the blade, lower the risk of deformation, breakage, and other damage caused by uneven stress, and thus extend the service life of the blade.

[0023] The pivot position of the central axis helps the blades maintain good balance during rotation, and the blades will not generate additional vibration and sway due to the shift of the center of gravity during rotation.

[0024] The fact that the pivot is located on the central axis makes the blades' obstruction and guidance of airflow more precise and stable when they rotate, thus more effectively controlling the direction, speed and flow distribution of airflow.

[0025] In some embodiments, the cross-section of the integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device is rectangular.

[0026] Rectangular structures are relatively simple to manufacture. Whether it's cutting and welding metal sheets or making molds, they are easier to standardize and mass-produce than circular or other irregularly shaped structures. Rectangular cross-section devices can better adapt to the rectangular spatial layout of factory buildings, allowing for closer integration with other equipment and building structures, and reducing space waste.

[0027] The relatively regular internal space of a rectangular cross-section is conducive to the uniform distribution of airflow. During waste gas treatment, a uniform airflow distribution ensures sufficient contact between the waste gas and the adsorption catalyst and reaction medium, improving treatment efficiency and effectiveness. The rectangular structure provides greater flexibility for the arrangement of components such as the internal airflow rectification and distribution structure, the adsorption-catalytic reaction zone, and the terminal catalytic oxidation reaction zone.

[0028] Preferably, the blade body is rectangular.

[0029] Rectangular blades provide a more stable and uniform obstruction and guidance effect on airflow during rotation. The shape and size of rectangular blades are easier to design and manufacture precisely, allowing for more accurate control of the exhaust gas flow rate. By adjusting the rotation angle of the rectangular blades, the exhaust gas flow rate can be precisely adjusted to meet the treatment needs under different operating conditions.

[0030] In a further preferred embodiment, several airflow regulating blades are uniformly arranged along a cross-section perpendicular to the direction of exhaust gas flow.

[0031] More preferably, when each blade body is perpendicular to the exhaust gas flow direction, it covers at least 1 / 2 of the cross-sectional area of ​​the device.

[0032] In some embodiments, VOCs concentration detectors are provided at the air inlet, the two adjacent adsorption catalytic reaction zones, and the air outlet.

[0033] In some embodiments, the air inlet is an expanded diameter structure along the exhaust gas flow direction; the air outlet is a reduced diameter structure along the exhaust gas flow direction.

[0034] In some embodiments, microwave feeding devices are provided on both sides of the first adsorption catalytic reaction zone and the second adsorption catalytic reaction zone, and on the same side, two adjacent microwave feeding devices are arranged orthogonally.

[0035] If the microwave feed devices are set in parallel, the emitted microwaves may overlap in some areas, resulting in excessive local energy, while in other areas they may cancel each other out, causing energy waste and uneven distribution.

[0036] When microwave feed devices are orthogonally arranged, the microwaves they emit propagate perpendicularly to each other in space, reducing interference between microwave energies. This allows for a more uniform distribution of microwave energy within the reaction zone, improving energy utilization and ensuring that each adsorbed catalyst receives stable microwave energy, thereby enhancing the efficiency and stability of the catalytic reaction.

[0037] In some embodiments, the packing material in the adsorption catalytic zone is a glass fiber corrugated packing material coated with an adsorption catalyst.

[0038] Glass fiber corrugated carriers have low dielectric loss and microwave transparency, allowing microwaves to efficiently penetrate to the adsorption-catalytic materials loaded on the surface. At the same time, the carrier has low density and extremely low specific heat capacity, resulting in rapid bed heating and cooling. After regeneration, it can be quickly cooled to the adsorption temperature, providing key support for alternating regeneration in zones and rapid recovery of adsorption, and significantly improving the continuous operation capability of the device.

[0039] In some embodiments, the terminal catalytic oxidation reaction zone has a circular cross-section perpendicular to the exhaust gas flow direction, and the microwave feed device is installed in a tangential microwave feed manner.

[0040] By employing microwave tangential feeding, energy is concentrated, field strength is uniform, and heating rate is fast, forming a stable high-temperature catalytic protection layer for the deep degradation of residual VOCs.

[0041] In some embodiments, the packing material in the terminal catalytic oxidation zone is a glass fiber corrugated packing material coated with a microwave-absorbing catalyst.

[0042] In some embodiments, temperature sensors are distributed in different areas of the first adsorption catalytic reaction zone and the second adsorption catalytic reaction zone. The temperature sensors are glass fiber thermometers or armored thermocouples, preferably glass fiber thermometers (0~300℃). A temperature sensing element is installed at the center of the flue gas outlet behind the terminal catalytic oxidation zone to monitor and control the temperature of the microwave catalytic oxidation zone.

[0043] Preferably, it also includes a controller, which is connected to each temperature sensor, each VOCs concentration detector, each drive motor and microwave feed device.

[0044] Secondly, the present invention provides an integrated treatment method for VOCs adsorption-desorption-in-situ catalytic oxidation, which is carried out using the aforementioned integrated treatment device and includes the following steps: When the VOCs concentration in the waste gas to be treated is higher than the emission standard limit, the waste gas is introduced from the inlet and enters the adsorption-catalytic reaction zone for adsorption under the rectification and distribution of the airflow rectification and distribution structure. The gas purified by adsorption is discharged from the outlet. When the concentration of VOCs in the exhaust gas exceeds the set value, the adsorption catalyst regeneration process is activated, and the inlet flow rate of the exhaust gas is reduced to serve as the exhaust gas carrier gas. First, start the microwave feed device of the terminal catalytic oxidation reaction zone to heat it to the catalytic decomposition temperature of VOCs and above; then turn on the microwave feed device of the first adsorption catalytic reaction zone and / or the second adsorption catalytic reaction zone to heat the inside, so that the VOCs adsorbed on the adsorption catalyst are desorbed and catalytically degraded in situ. At the same time, the waste gas carrier gas carries out the degraded gas, and the VOCs in the waste gas carrier gas are catalytically degraded by the adsorption catalyst. During the regeneration process, the airflow rectification and distribution structure distributes the waste gas carrier gas in the cross-sectional direction, so that the temperature of the adsorbed catalyst is evenly distributed in the cross-sectional direction.

[0045] The terminal catalytic oxidation reaction zone is the key area where VOCs are ultimately oxidized and decomposed into harmless substances. Preheating it to the catalytic decomposition temperature of VOCs or above provides a stable high-temperature reaction environment for the subsequently desorbed VOCs. When the residual VOCs exit the adsorption catalytic reaction zone and enter the terminal catalytic oxidation reaction zone, they can immediately undergo an oxidation reaction under suitable temperature and catalyst conditions, ensuring the complete decomposition of VOCs.

[0046] In in-situ catalytic degradation, the temperature uniformity of the adsorption catalyst bed directly affects the efficiency of the catalytic reaction. Excessively high or low temperatures will affect catalyst activity, leading to a decrease in the catalytic reaction rate. Uniform temperature allows the active sites on the catalyst surface to fully function, promoting the catalytic degradation of VOCs and improving degradation efficiency. Simultaneously, uniform temperature can also reduce the occurrence of side reactions, ensuring the safety and effectiveness of waste gas treatment.

[0047] Uneven temperature can lead to localized overheating or undercooling of the adsorption catalyst bed, causing changes in thermal stress in the material and accelerating the detachment and deactivation of the adsorption catalyst from the support. By setting a uniform temperature in the adsorption catalyst bed, the impact of temperature variations on the adsorption catalyst can be reduced, extending its service life and lowering operating costs.

[0048] The airflow rectification and distribution structure can distribute the waste gas carrier gas entering the adsorption catalytic reaction zone in the cross-sectional direction. If the temperature of a certain area is too high, the flow rate of the waste gas flowing through that area can be increased; if the temperature of a certain area is too low, the flow rate of the waste gas flowing through that area can be reduced. This effectively regulates the temperature of the adsorption catalyst bed in that area, thereby ensuring the uniformity and efficiency of VOCs desorption and in-situ catalytic degradation.

[0049] In some embodiments, during the regeneration process, the first adsorption catalytic reaction zone is regenerated first, and after regeneration is completed, its microwave feed device is turned off; then the second adsorption catalytic reaction zone is regenerated, and after regeneration is completed, its microwave feed device is turned off, and the microwave feed device of the terminal catalytic oxidation reaction zone is also turned off.

[0050] During the regeneration process, the adsorption catalytic reaction zone is continuously heated by microwaves, resulting in a high temperature for the adsorption catalyst. Therefore, after regeneration, it cannot be directly used for VOCs adsorption in the waste gas. Thus, the first adsorption catalytic reaction zone is regenerated first, and after regeneration, its microwave feed device is turned off before regenerating the second adsorption catalytic reaction zone. During this process, the waste gas carrier gas is continuously introduced. While the second adsorption catalytic reaction zone is being regenerated, the first adsorption catalytic reaction zone, after regeneration, can be simultaneously cooled down, allowing for VOCs adsorption.

[0051] This partitioned regeneration method enables continuous, uninterrupted operation of a single device.

[0052] In some embodiments, during the adsorption stage, the angle of the blade body of the airflow rectification and distribution structure is adjusted so that the airflow channel in the central region is smaller than the airflow channels on both sides. This increases the edge airflow distribution, improves the utilization rate of the adsorbent at the edge of the bed, and avoids adsorption blind zones.

[0053] When exhaust gas enters the adsorption catalytic reaction zone, the airflow velocity and flow rate are generally higher in the central area. Without adjustment, the adsorption catalyst in the central area will adsorb a large amount of VOCs in a short time, reaching saturation, while the adsorption catalysts in the lateral areas still have significant adsorption potential. By reducing the airflow channel size in the central area, the airflow velocity and flow rate can be reduced, decreasing the adsorption load on the central adsorption catalyst and preventing over-saturation. Simultaneously, the adsorption catalyst at the edges of the adsorption catalytic reaction zone is fully utilized, improving its utilization rate.

[0054] In some embodiments, the inlet flow rate of the exhaust gas during the regeneration process is 1 / 20 to 1 / 5 of the inlet flow rate of the exhaust gas during the adsorption process.

[0055] During adsorption, waste gas passes through the adsorption catalytic reaction zone at a relatively high flow rate, and VOCs are adsorbed onto the surface of the adsorption catalyst. During regeneration, the inlet flow rate of the waste gas is set to 1 / 20 to 1 / 5 of that during adsorption. In this case, the introduced waste gas acts as a desorption medium, assisting in the desorption of VOCs adsorbed by the catalyst. A lower flow rate of waste gas significantly increases the residence time of the waste gas in the adsorption catalytic reaction zone. This longer residence time allows for sufficient contact between the waste gas and the adsorption catalyst, giving the VOCs adsorbed on the catalyst surface enough time to desorb, improving desorption efficiency, ensuring complete desorption of VOCs, and preventing residual VOCs from affecting the re-adsorption capacity of the catalyst.

[0056] In some embodiments, the adsorption catalyst comprises an adsorbent and a catalyst active component supported on the surface of the adsorbent, wherein the loading of the catalyst active component is 10-30 wt%, the adsorbent is a zeolite molecular sieve, and the catalyst active component is FeMnCeO. x Graphene-doped manganese oxide or Co3O4-MnO2-CuO composite catalysts.

[0057] The adsorption catalyst of this invention comprises an adsorbent and a catalyst active component supported on the surface of the adsorbent. The adsorbent serves two purposes: firstly, to support the catalyst active component, and secondly, to adsorb VOCs from the waste gas. When the loading of the catalyst active component is too small, although there is more space available for VOCs adsorption, its catalytic activity is low, which is detrimental to improving the catalytic degradation efficiency of VOCs. When the loading of the catalyst active component is too large, although there are sufficient catalytic active sites, the space on the adsorbent available for VOCs adsorption is reduced, resulting in a decrease in VOCs adsorption efficiency, which is also detrimental to improving the waste gas treatment efficiency.

[0058] The active component of the catalyst of the present invention is a non-precious metal oxide with high dielectric loss, strong microwave absorption, and high activity at low temperature.

[0059] Preferably, the adsorbent is selected from at least one of 13X, MCM 41, ZSM-5, NaY, USY, HY, and Beta molecular sieves; preferably, the support is selected from one or a combination of ZSM-5, HY, USY, or Beta molecular sieves.

[0060] More preferably, the adsorbent is a hydrophobic molecular sieve Beta-USY composite molecular sieve, and the mass ratio of the Beta and USY phases is 1:9 to 9:1, preferably 5:5 (that is, the mass of Beta and USY each accounts for 50%, abbreviated as UB50).

[0061] This composite adsorbent has advantages such as hydrophobicity and moisture resistance, and wide pore size distribution, which can effectively inhibit the polymerization and pore blockage of VOCs such as styrene.

[0062] Preferably, the graphene doping amount in the graphene-doped manganese oxide is 0.5 to 8 wt%, such as 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, or 8 wt%.

[0063] Preferably, in the graphene-doped manganese oxide composite catalyst, the doping amount of graphene is 4~7wt%. This catalyst has strong resistance to poisoning.

[0064] Preferably, in the adsorption catalyst, the loading of the catalyst active component on the adsorbent is 10~20wt%.

[0065] The composite material retains ≥50% of the original molecular sieve's adsorption capacity.

[0066] More preferably, the adsorption catalyst is 15-6-GO / MnO2@UB50, wherein 15 represents the GO / MnO2 loading rate on the UB50 molecular sieve as 15 wt%, and 6 represents the graphene doping rate in the graphene-doped manganese oxide composite catalyst GO / MnO2 as 6 wt%.

[0067] In some embodiments, when the concentration of VOCs in the waste gas to be treated is higher than a set value, the catalyst packing is heated to 200~300°C by microwave, and the VOCs in the waste gas to be treated undergo direct catalytic oxidation and decomposition on the catalyst surface.

[0068] Preferably, the microwave is turned off when the exothermic reaction of catalytic oxidation is sufficient to maintain the bed temperature; when the temperature of the catalyst packing drops due to fluctuations in the concentration of VOCs in the exhaust gas, the microwave is turned on for auxiliary heating.

[0069] The present invention will be further described below with reference to the embodiments.

[0070] Example 1 like Figure 1 and Figure 2 As shown, an integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device consists of an air inlet 1, an airflow rectification and distribution structure 2, a first adsorption catalytic reaction zone 3, a second adsorption catalytic reaction zone 4, an end catalytic oxidation reaction zone 5, and an air outlet 6, arranged sequentially from one side to the other. A microwave generator 7 is installed on the outer shell of each of the three adsorption catalytic reaction zones. The airflow rectification and distribution structure 2 is arranged perpendicular to the direction of the waste gas flow and includes several airflow regulating blades 21 arranged in parallel. Each airflow regulating blade 21 includes a blade body 211 and a blade shaft 212. The blade body 211 is disposed on the blade shaft 212. The end of the blade shaft 212 is connected to the drive motor 23 through a coupling 22. By adjusting the rotation angle of each airflow regulating blade 21, the width of the airflow channel is adjusted, and the airflow is rectified and distributed along the cross-sectional direction. The drive motor 23 is mounted through a motor bracket 24.

[0071] Each adsorption-catalysis reaction zone is equipped with a microwave feed device on its exterior and packing material inside, with adsorption catalyst attached to the packing material.

[0072] The blade shaft 212 is located on the central axis of the blade body 211; the cross-section of the integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device is rectangular; the blade body 211 is rectangular; Several airflow regulating blades 21 are evenly arranged along a cross section perpendicular to the direction of exhaust flow; when each blade body 211 is perpendicular to the direction of exhaust flow, it covers at least 1 / 2 of the cross-sectional area of ​​the device. VOCs concentration detectors 11 are installed at the air inlet 1, the two adjacent adsorption catalytic reaction zones, and the air outlet 6.

[0073] The air inlet 1 is an expanded structure along the direction of exhaust gas flow; the air outlet 6 is a reduced structure along the direction of exhaust gas flow.

[0074] Microwave feed devices are provided on both sides of the first adsorption catalytic reaction zone 3 and the second adsorption catalytic reaction zone 4. On the same side, two adjacent microwave feed devices are arranged orthogonally. The end catalytic oxidation reaction zone has a circular cross-section perpendicular to the direction of waste gas flow, and microwaves are fed tangentially from the microwave feed devices.

[0075] Specifically, the dimensions of the bed obtained by the filler can be 30-40cm in length, 30-40cm in width, and 30-40cm in height.

[0076] Temperature sensors, specifically glass fiber thermometers 12, are distributed across different areas of the first adsorption catalytic reaction zone 3 and the second adsorption catalytic reaction zone 4. These thermometers can collect real-time data on the internal temperature field of the bed, obtaining key parameters such as the temperature difference between the center and the edge, and the heating rate of each zone. After the terminal catalytic oxidation zone, a temperature sensing element 13 is installed at the center of the flue gas outlet to monitor and control the temperature of the microwave catalytic oxidation zone.

[0077] The air inlet 1 is used to introduce the VOCs waste gas to be treated; the airflow rectification and distribution structure 2 is used to rectify the inlet airflow and achieve uniform air distribution; the first adsorption catalytic reaction zone 3 is used for the first stage of VOCs adsorption and in-situ catalytic oxidation; the second adsorption catalytic reaction zone 4 is used for the second stage of VOCs adsorption and in-situ catalytic oxidation; the terminal catalytic oxidation reaction zone is used for the deep catalytic oxidation of residual VOCs; and the air outlet 6 is used to discharge the purified gas.

[0078] The reactor shell 8 is used to accommodate each reaction zone and form a sealed flow channel; the insulation layer 9 is used to reduce heat loss and suppress overheating of the outer wall; the gap 10 is used to separate adjacent reaction zones; the VOCs concentration detector 11 is used to detect the VOCs concentration at the inlet, interval, and outlet; the glass fiber thermometer 12 is used to collect the temperature signal of the adsorption catalytic bed in real time; the temperature sensing element 13 is used to monitor and control the temperature of the microwave catalytic oxidation area. The PLC control unit 14 is connected to each sensor and motor to adjust the microwave power and airflow distribution in a coordinated manner.

[0079] like Figure 4 and Figure 5As shown, the airflow regulating blade 21 is used to adjust the air distribution ratio between the center and the edge regions; the coupling 22 is used to connect the blade shaft 212 and the drive motor 23; the drive motor 23 is used to drive the airflow regulating blade 21 to rotate; the motor bracket 24 is used to install and fix the drive motor 23. The blade body 211 is used to form the dominant flow surface; the blade shaft 212 is used to cooperate with the coupling 22 to realize the blade rotation.

[0080] like Figure 6 As shown, the first microwave feeding device 41 is used to feed microwave energy into the adsorption-catalytic reaction zone; the packing material 42 is used to adsorb VOCs and perform in-situ catalytic oxidation. The second microwave feed device 51 is used to feed microwave energy into the end catalytic oxidation reaction zone; the cylindrical catalytic packing 52 is used for deep catalytic oxidation of residual VOCs.

[0081] The cylindrical catalytic packing 52 in the terminal catalytic oxidation reaction zone 5 has a diameter of 30-40 cm and a thickness of 15-20 cm. This catalytic module is a module formed by supporting a microwave-absorbing non-precious metal catalyst on a glass fiber corrugated structured support. Figure 3 , Figure 7 and Figure 8 As shown. A temperature sensing element 13 is installed inside the terminal catalytic oxidation reaction zone 5 for temperature control and heating of its interior.

[0082] Glass fiber corrugated carriers have low dielectric loss and microwave transparency, allowing microwaves to efficiently penetrate to the adsorption-catalytic materials loaded on the surface. At the same time, the carrier has low density and extremely low specific heat capacity, resulting in rapid bed heating and cooling. After regeneration, it can be quickly cooled to the adsorption temperature, providing key support for alternating regeneration in zones and rapid recovery of adsorption, and significantly improving the continuous operation capability of the device.

[0083] The adsorption catalyst comprises an adsorbent and a catalyst active component supported on the surface of the adsorbent. The loading of the catalyst active component is 10-30 wt%. The adsorbent is a hydrophobic zeolite molecular sieve, and the catalyst active component is FeMnCeO. x Graphene-doped manganese oxides or Co3O4-MnO2-CuO composite catalysts, such as Figure 9 As shown.

[0084] The metal oxide catalytic layer in the adsorption catalyst has a high dielectric loss factor, which can selectively absorb microwaves and convert them into heat energy, thereby achieving targeted heating of catalytic active sites, greatly improving microwave energy utilization, and promoting rapid desorption and in-situ catalytic oxidation of VOCs.

[0085] During actual runtime: Air distribution: The air intake module mainly consists of an air intake port and a housing. Inside the housing, there are 4 to 8 blades, which are installed in the bearing holes of the housing. The blades are connected to a rotating motor through a coupling. When the motor rotates, it can drive the blades to rotate 360°. The motors are arranged in parallel and are installed on the motor frame and placed in a closed housing to prevent gas leakage.

[0086] Adsorption process: Reduce the opening of the central valve, increase the distribution of airflow at the edge, improve the utilization rate of adsorbent at the edge of the bed, and avoid adsorption blind zones; Regeneration process: The fan frequency, airflow distribution and microwave system work together to first reduce the inlet air volume to 1 / 20 to 1 / 5 of the adsorption air volume by adjusting the fan frequency; the air distribution ratio is adjusted in real time according to the temperature difference between the center and edge of the bed, increasing the edge air volume and reducing the center air volume to achieve uniform heating throughout the entire area with a temperature difference ≤15℃, avoiding local overheating, incomplete desorption or VOCs escaping before degradation.

[0087] (3) Microwave zoned feed and precise temperature control system Single-zone microwave output power: 8~12kW; single microwave source power is 1~1.5kW, with multi-point distributed arrangement; three zones have independent start / stop, independent power adjustment, and independent temperature control.

[0088] Microwave sources are arranged on the upper and lower planes of each adsorption-catalytic reaction zone with (1 / 3x, 1 / 3y), (1 / 3x, 2 / 3y), (2 / 3x, 1 / 3y), and (2 / 3x, 2 / 3y) as the center points. Adjacent microwave sources in the same plane are arranged orthogonally, and the microwave sources on the upper and lower planes are also arranged orthogonally to each other. Through spatial orthogonal coupling, the microwave field is made more uniform, and the local overheating and undercooling temperature difference is significantly reduced.

[0089] Temperature measurement and closed-loop temperature control: The temperature measurement points are precisely located at (1 / 2x, 1 / 2y, 1 / 3z) and (1 / 2x, 1 / 2y, 1 / 2z); a high-temperature resistant glass fiber thermometer is used to collect the internal temperature of the bed in real time; the PLC system automatically adjusts the airfoil multi-blade airflow distribution valve according to the real-time temperature difference signal of the bed, and dynamically matches the center / edge air distribution ratio, thereby ensuring that the temperature field of the bed is highly uniform and stable.

[0090] The end-stage deep catalytic zone uses microwave tangential feeding, which concentrates energy, provides uniform field strength, and has a fast heating rate, forming a stable high-temperature catalytic protection layer for the deep degradation of residual VOCs.

[0091] Multi-point online detection: Three-point online VOCs concentration detection is set up along the airflow direction, combined with multi-point bed temperature monitoring: Inlet monitoring point: Real-time monitoring of VOCs inlet concentration, fluctuation range and load changes to provide a basis for judging the operation mode; Detection point between Zone 1 and Zone 2: accurately capture the position of the adsorption front, determine the adsorption saturation progress, predict the regeneration start-up time in advance, and avoid VOCs penetration; Export detection point: Monitors the final purified gas concentration to determine whether emissions meet standards, and also serves as the core trigger signal for starting the regeneration process and adjusting the catalytic intensity.

[0092] The system is also equipped with a glass fiber thermometer to collect the internal temperature field of the bed in real time, obtaining key parameters such as the temperature difference between the center and the edge, and the heating rate of each zone. The PLC control system is based on dual linkage of concentration signal and temperature signal, automatically executing closed-loop control of the entire process: adsorption → concentration prediction regeneration → end catalytic preheating → zoned microwave regeneration → in-situ catalytic oxidation → rapid cooling → adsorption recovery, realizing uninterrupted, continuous, and automated operation of the device without human intervention, and adapting to complex operating conditions with large air volume and concentration fluctuations.

[0093] The integrated VOCs treatment method is as follows: The operating mode is automatically switched according to the inlet VOCs concentration to achieve adaptive and efficient treatment over a wide concentration range.

[0094] (1) For low to medium concentration waste gas: adsorption-regeneration-in-situ catalysis mode (<1000 ppm) a. Adsorption stage: At room temperature, the waste gas is introduced into the reactor, where VOCs are efficiently adsorbed by the hydrophobic molecular sieve in the core of the core-shell structured adsorption catalyst; the gas flows through the glass fiber corrugated carrier to form a turbulent channel, which enhances gas-solid mass transfer and purifies the gas to meet emission standards.

[0095] b. Microwave regeneration and in-situ catalysis stage: When the VOCs concentration at the outlet detection point reaches the preset threshold, the PLC automatically starts the regeneration program. Microwaves are first activated in the terminal deep catalytic zone to preheat the zone to 220~300℃, thereby constructing a stable high-temperature catalytic protection layer to prevent VOCs from escaping during the regeneration process. Turn on the microwave feed device in the first adsorption-catalysis reaction zone and control the bed temperature to 120~250℃; the microwave selectively acts on the polar VOCs, which promotes the rapid desorption of adsorbed VOCs. The catalytic layer selectively absorbs microwave energy and heats up rapidly, and catalyzes the oxidation of VOCs to CO2 and H2O in situ at the high-temperature catalytic site. When the VOCs concentration at the detection point between the first adsorption-catalysis reaction zone and the second adsorption-catalysis reaction zone is lower than the inlet concentration, it is determined that the regeneration of the first adsorption-catalysis reaction zone is complete, and the microwave feed device of the first adsorption-catalysis reaction zone is turned off; at the same time, the microwave feed device of the second adsorption-catalysis reaction zone is turned on, and regeneration and in-situ catalysis are performed according to the same parameters.

[0096] After each zone is regenerated, the microwave is turned off sequentially. Relying on the rapid cooling characteristics of the glass fiber corrugated carrier, the bed quickly returns to the adsorption temperature and is put back into adsorption, achieving continuous operation without stopping.

[0097] (2) For high-concentration waste gas (VOCs concentration ≥1500 ppm), direct catalytic oxidation mode is used: The device automatically switches to catalytic reactor operation mode, rapidly heating the bed to 200~300℃ using multi-point distributed microwaves; VOCs undergo direct catalytic oxidation and decomposition on the surface of the catalytic layer; when the exothermic reaction is sufficient to maintain the bed temperature, the system automatically reduces or shuts down the microwave power; when concentration fluctuations cause the bed temperature to drop, the microwave system automatically intervenes to assist in heating and temperature control, ensuring continuous, stable, safe, and low-energy operation of the reaction.

[0098] Example 2 Screening of adsorption catalysts: A hydrophobic Beta-USY composite molecular sieve was used as the adsorbent, wherein the mass ratio of Beta to USY in the composite molecular sieve was 1:1, abbreviated as UB50. Using a co-precipitation method, the loading rate of Fe-Mn-Ce on the UB50 molecular sieve was adjusted (0~30%) to obtain x% Fe. 0.85 -Mn 0.1 -Ce 0.05 @UB50 composite structure microporous functional material.

[0099] The specific preparation method of the coprecipitation method is as follows: First, 11 g of sodium oxalate was dissolved in 150 ml of deionized water to form a saturated solution. Approximately 2 g of FeSO4·7H2O, 0.129 g of MnSO4, and 0.073 g of CeN3O9·6H2O were dissolved in deionized water at a molar ratio. The solution was stirred at 40 °C for 1 h to ensure complete dissolution. Next, 4 g of molecular sieve UB50 was dispersed into the solution, stirred until dissolved, and then sonicated for 30 minutes to enhance complexation. The resulting solution was then transferred to a saturated sodium oxalate solution and stirred for 1 h. After precipitation, the supernatant was allowed to become clear before filtration. The resulting sample was 10% Fe0.85-Mn0.1-Ce0.05 / UB50. The sample was washed twice or more with deionized water and centrifuged. The centrifuged composite catalyst was dried at 60 °C for 10 h and finally calcined at 300 °C for 2 h at a heating rate of 1 °C / min to obtain the final sample.

[0100] Under the same mass of molecular sieve, the mass of FeSO4·7H2O, MnSO4, and CeN3O9·6H2O were increased exponentially in the control group, resulting in 20% Fe... 0.85 -Mn 0.1 -Ce 0.05@UB50、30% Fe 0.85 -Mn 0.1 -Ce 0.05 @UB50 sample.

[0101] As shown in Table 1, the BET test indicates that 20% Fe 0.85 -Mn 0.1 -Ce 0.05 The @UB50 composite material retains approximately 70% of the original molecular sieve's specific surface area and pore volume. This composite material achieves a catalytic combustion conversion rate of over 90% for toluene at 230℃.

[0102] Table 1 BET Test Results

[0103] The adsorption and catalytic performance testing method for the adsorption catalyst is as follows: The testing system consists of a mass flow control system, a VOCs generation system, an adsorption / catalytic bed, and gas adsorption detection and gas composition detection units.

[0104] The mass flow control system includes a gas cylinder pressure reducing valve and a mass flow meter. The pressure reducing valve controls the gas back pressure, and the mass flow meter controls the gas flow rate. In experiments, the gas flow rate is generally set to 300 mL / min, which can be controlled and adjusted under different operating conditions.

[0105] In the VOCs generation system, liquid toluene is injected into the VOCs generator via a micro-injector and vaporized into gaseous toluene at 110°C. The toluene concentration is controlled at 500 ppm by adjusting the injection rate and carrier gas flow rate. To prevent condensation of the simulated gas, a heating cable is wrapped around the outside of the tubing for insulation. Synthetic air is used as the carrier gas, which carries the gaseous toluene through the VOCs generator into the fixed bed of the gas catalyst.

[0106] The fixed bed of adsorption catalyst is placed in a hollow quartz glass tube with an inner diameter of 10 mm and 35 mm. A quartz partition is fixed inside the reactor. For each experiment, 40-60 mesh powdered adsorption catalyst is placed on the partition, with both ends secured by quartz wool to prevent fine powder particles from being blown away by the airflow. After securing, the mixture is introduced into the detection unit for adsorption detection or catalytic oxidation performance testing. During catalytic oxidation performance testing, the glass tube is placed in an electric heating furnace, and the catalytic material inside is heated according to a pre-set heating program.

[0107] Gas adsorption detection is mainly performed at the adsorption bed outlet, and is completed by real-time online monitoring and data acquisition using a portable VOCs detector. The portable VOCs detector uses a PID photoionization sensor, which can ionize gas molecules into positively and negatively charged ions, which are then captured by a charge sensor to form a current signal. The detection range is 0-10000ppm, and the detection accuracy error is ≤2%. By continuously recording the outlet VOCs concentration at each time interval, a dynamic adsorption breakthrough curve is obtained, and the saturated adsorption capacity is calculated. The calculation formula is shown in equation (1). ; In the formula, q is the saturated adsorption capacity, mg / g; F is the gas flow rate, ml / min; m is the adsorbent mass, g; C0 and C t VOCs inlet and outlet concentrations, mg / m³ 3 t represents the adsorption time, in minutes.

[0108] Gas composition detection involves passing the outlet gas from the electric heating furnace into a gas chromatograph for concentration analysis. The gas chromatograph mainly consists of a flame ionization detector (FID) and a capillary column, allowing for online detection of VOC concentrations. The catalytic oxidation efficiency is determined by the VOC conversion rate (…). X VOCs , %) represents the value, and the calculation formula is shown in equation (2): ; In the formula [ VOCs ] in and[ VOCs ] out These represent the inlet and outlet concentrations of the simulated VOCs gas, respectively, in mg / m³. 3 .

[0109] Furthermore, Sco2 and Sco represent the selectivity of CO2 and the selectivity of CO, respectively, to calculate the amount of VOCs converted into CO2 and CO, as shown in formulas (3) and (4):

[0110]

[0111] In the formula [ Toluene ] in 、[ Toluene ] out These represent the toluene concentration before and after the reaction, respectively; [CO2] and [CO] represent the CO2 and CO concentrations at the outlet, respectively; the number "7" represents the number of C atoms in toluene, meaning that 1 mole of toluene is theoretically converted into 7 moles of CO2 or CO.

[0112] Figure 10 For x% Fe0.85 -Mn 0.1 -Ce 0.05 / UB50 catalyst, a comparison chart of catalytic performance tests when x takes different values, from Figure 10 It can be seen that among the three adsorption catalysts, 20% Fe0.85-Mn0.1-Ce0.05@UB50 exhibits superior catalytic oxidation performance, with a T90 temperature of 230℃.

[0113] The catalytic activity of 20% Fe0.85-Mn0.1-Ce0.05 / UB50 under different mass air velocities was further investigated. Although the temperature required for catalytic degradation efficiency shifted slightly to the higher temperature range with increasing gas space velocity, the corresponding T90 temperature gradually increased from 225℃ (90000 mL / (g·h)) to 228℃ (120000 mL / (g·h)), 232℃ (150000 mL / (g·h)), and finally reached 248℃ (180000 mL / (g·h), as shown in the figure. Figure 11 As shown, it still maintains high catalytic activity overall (T90 < 250℃).

[0114] Dielectric constant test of x%Fe-Mn-Ce / UB50 sample group: After loading with FeMnCe catalyst, the absorption characteristics of the composite material are significantly enhanced, especially those of 20% Fe. 0.85 -Mn 0.1 -Ce 0.05 @UB50, as Figure 12 As shown in Figures a, b, and c, the Fe-Mn-Ce ternary composite oxide monomer catalyst exhibits excellent dielectric properties. Both the real and imaginary parts of the dielectric constant are at high levels, and the loss tangent is considerable, indicating good microwave absorption and self-heating characteristics, enabling rapid heating and efficient energy conversion in microwave fields. In contrast, the porous molecular sieve-based material UB50 exhibits almost no dielectric properties, with extremely low imaginary parts and loss tangents, showing virtually no response to microwave electric fields and exhibiting typical dielectric inertness. After loading the Fe-Mn-Ce active component onto the molecular sieve support, the dielectric properties of the composite material change significantly. Both the real and imaginary parts of the dielectric constant increase to a moderate level, and the loss tangent also increases accordingly, indicating that the material has transformed from a dielectrically inert state into a microwave-responsive material with dielectric activity. The high-performance 20% Fe-Mn-Ce@UB50 material exhibits high real part (ε′≈ 2.6), imaginary part (ε″ ≈ 0.1), and tangent (tan δ ≈ 0.05) dielectric constant values ​​in a specific frequency band, which are close to the level of Fe-Mn-Ce monomer. This activation of dielectric properties is mainly attributed to the introduction of active components and the interfacial polarization effect generated at the interface between active components and the support.

[0115] Therefore, the Fe-Mn-Ce@UB50 composite material achieves a transformation of dielectric properties from "inert" to "active" through the loading of active components. Among them, 20% Fe-Mn-Ce@UB50, while maintaining the porous structure of the support, achieves a significant improvement in dielectric properties, providing an ideal dielectric basis for rapid self-heating and efficient catalytic reactions under microwave fields.

[0116] 20% Fe after toluene adsorption saturation 0.85 -Mn 0.1 -Ce 0.05 Using UB50 (0.2g) as the target, direct microwave irradiation was performed, and the CO2 concentration in the gas after the reaction was detected, finding that it instantly reached 7000ppm. Figure 13 As shown, this indicates that the desorbed VOCs were effectively degraded in situ.

[0117] Example 3 Screening of xy-GO / MnO2@UB50 composite catalysts: Graphene-manganese oxide was loaded onto UB50 zeolite molecular sieve using a one-step hydrothermal method to obtain xy-GO / MnO2@UB50 composite material.

[0118] The specific preparation method is as follows: First, 8.6 mL of graphene oxide suspension (700 mg / L) was diluted with deionized water to a total volume of 60 mL. Then, 0.79 g of KMnO4 and 0.32 g of MnSO4·H2O were added, and the mixture was magnetically stirred for 30 minutes until completely dissolved. Next, 2 g of UB50 molecular sieve was added to the solution to form a precursor suspension. The mixture was stirred and sonicated for 30 minutes to enhance dispersibility and strengthen the interaction between the molecular sieve interface and the active ingredient. The mixed solution was transferred to a 100 mL polytetrafluoroethylene-lined reactor and kept at 150°C for 12 h. After the reaction, the solid product was centrifuged, washed three times with deionized water, and dried in a forced-air drying oven at 105°C for 12 h. The resulting composite material was denoted as 15-2-GO / MnO2@UB50 (where "15" represents the MnO2 loading rate on the UB50 zeolite, and "2" represents the mass percentage of GO relative to MnO2).

[0119] Using the same synthetic scheme, 10-2-GO / MnO2@UB50 and 20-2-GO / MnO2@UB50 composites were prepared by adjusting the proportions of KMnO4 and MnSO4·H2O. Similarly, 15-4-GO / MnO2@UB50 and 15-6-GO / MnO2@UB50 were synthesized by increasing the amount of GO suspension to 17.2 mL and 25.8 mL, respectively.

[0120] For comparative studies, unloaded 2-GO / MnO2 composite materials were prepared using the same process without the addition of UB50 zeolite.

[0121] As shown in Tables 2 and 3, for composite materials with different 2-GO / MnO2 loadings (10%, 15%, and 20%), the specific surface area, micropore volume, and toluene adsorption capacity within the same time period all decreased with increasing loading, following a pattern of 10% > 15% > 20%. This indicates that the catalyst loading leads to a partial loss of micropore volume in UB50. Regarding the effect of GO content, when the MnO2 loading is kept at 15%, although increasing the GO doping amount (from 2% to 6%) leads to a decrease in specific surface area, micropore volume, and adsorption capacity, the overall impact of graphene doping on adsorption characteristics is relatively small compared to the MnO2 loading amount.

[0122] Considering that the loading amount directly affects catalytic activity, the composite material with a MnO2 loading of 15% maintains a high specific surface area, a well-distributed micro / mesoporous structure, and efficient mass transfer channels. This structural synergy ensures that VOCs molecules have sufficient adsorption sites (provided by micropores) and unobstructed diffusion paths (promoted by mesopores), thereby achieving efficient adsorption and catalytic degradation of VOCs.

[0123] Table 2. Specific surface area, pore volume, and pore size of composite materials

[0124] Table 3 Adsorption capacity of xy-GO / MnO2@UB50 adsorption catalyst

[0125] Figure 14 This is a comparison chart of toluene conversion rates for various adsorption catalysts at different catalytic oxidation temperatures. Figure 14 It can be seen that, at a certain temperature, 2-GO / MnO2 exhibits a more significant temperature response and higher degradation efficiency compared to the tested composite material. This trend is mainly attributed to its higher content of effective active components in the same mass (0.2 g) of catalyst. Pure 2-GO / MnO2 can achieve a toluene degradation rate of 90% at approximately 170°C, demonstrating its inherent high catalytic activity. Its excellent catalytic performance is not only due to its larger mesopore volume (0.301 cm³), but also... 3 The GO sheets (g) facilitate mass transfer and diffusion of toluene molecules; moreover, the GO sheets act as a conductive and dispersing matrix, anchoring MnO2 nanoparticles, preventing their aggregation, and promoting electron transfer during catalytic oxidation—these two factors together lower the activation energy barrier for the degradation of volatile organic compounds.

[0126] Observation of composite materials with the same GO content but different loading ratios (10%, 15%, 20%) shows that the composite material with a 15% loading exhibits the best low-temperature degradation stability, with a T90 value of 225°C. For composite materials with a fixed 15% loading but different GO contents (2%, 4%, 6%), the catalytic performance increases with increasing GO content, and the T90 value decreases from 225°C (2%) to 201°C (6%). Overall, 15-6-GO / MnO2@UB50 exhibits high adsorption capacity (183.46 mg / g) and catalytic activity (T90 = 201°C).

[0127] Furthermore, the dielectric constant was used to analyze the material's ability to absorb microwaves and convert them into heat energy under a microwave field, providing a direct reflection of the material's microwave heating characteristics. The dielectric constant was characterized using an Anritsu MS46122b vector network analyzer and a POS-141D probe. The complex dielectric constant and dielectric loss tangent were determined using the coaxial probe method. Before testing, 0.1g of the sample was weighed, dried, and pressed into a tablet. The network analyzer was connected to the probe and brought into contact with the flat surface of the material. The complex dielectric constant, loss tangent, and other performance parameters were measured and calculated within a set frequency range.

[0128] like Figure 15 As shown in a, b, and c, compared to UB50, GO / MnO2 exhibits higher real and imaginary dielectric constants and a higher loss tangent, demonstrating excellent microwave absorption and self-heating characteristics. The GO / MnO2-supported UB50 molecular sieve composite catalyst synthesized via a one-step hydrothermal method showed that the absorption characteristics of the composite material were significantly enhanced after loading with the GO / MnO2 catalyst, especially for 15-6-GO / MnO2@UB50. The 15-6-GO / MnO2@UB50 material exhibited higher real dielectric constant values ​​(ε′≈13), imaginary dielectric constant values ​​(ε″≈6), and loss tangent (tanδ≈0.5) in a specific frequency band, several orders of magnitude higher than UB50. This characteristic indicates that the material has transformed from "dielectrically inert" to "dielectrically active," possessing the ability to selectively and rapidly heat under microwaves, creating favorable conditions for the rapid initiation of in-situ catalytic degradation of VOCs under microwave irradiation.

[0129] Therefore, 15-6-GO / MnO2@UB50 was selected as the bulk material and loaded onto a structured carrier to obtain an integral composite material. Figure 16 To further load xy-GO / MnO2@UB50 onto a structured support, the adsorption curve (a) and desorption-degradation curve (b) of the prepared monolithic adsorption-catalyst under microwave irradiation are shown.

[0130] The adsorption capacity of the 15-6GM / UB50 monolithic adsorption-catalyst sample was approximately 214.01 mg / g after 2 hours, as measured by the adsorption curve. This is likely due to the increased specific surface area of ​​the bifunctional material loaded onto the support, leading to a slight increase in adsorption capacity compared to the monomer material. Microwave regeneration was performed on the adsorption-saturated material. Under conditions of WHSV = 100000 (ml / gh) and a toluene concentration of 250 ppm, a microwave source was used with a power of 1400 W. It was observed that within 5 minutes of microwave activation, the VOCs concentration remained consistent with the inlet gas concentration at 250 ppm, while the CO2 concentration ranged from 200 to 500 ppm. This was attributed to the use of a single-mode microwave heating device, which limited the heating area, allowing only a portion of the monolithic adsorption catalyst to initiate regeneration and in-situ degradation. After approximately 5 minutes, a large amount of CO2 was released, accompanied by a rapid decrease in toluene concentration, indicating that VOCs began to desorb and be degraded in situ. The core reason why this material achieves efficient adsorption-in-situ degradation integration under low-energy microwave heating conditions is that: First, the GO / MnO2 composite component has strong microwave absorption and excellent dielectric loss characteristics, which can rapidly heat up to 200℃ at low power (1400 W) to achieve in-situ thermal desorption and catalytic degradation; Second, the catalyst loading increases the specific surface area of ​​the composite material, enabling the in-situ degradation of desorbed VOCs.

[0131] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device, characterized in that: From one side to the other, the components are arranged in sequence: air inlet, airflow rectification and distribution structure, first adsorption-catalytic reaction zone, second adsorption-catalytic reaction zone, and terminal catalytic oxidation reaction zone. The airflow rectification and distribution structure is set perpendicular to the direction of the exhaust airflow and includes several airflow regulating blades arranged in parallel. Each airflow regulating blade includes a blade body and a blade shaft. The blade body is set on the blade shaft, and the end of the blade shaft is connected to the drive motor through a coupling. By adjusting the rotation angle of each airflow regulating blade, the airflow is rectified and distributed along the cross-sectional direction. Each adsorption-catalysis reaction zone is equipped with a microwave feed device on its exterior and a packing material inside, with an adsorption catalyst attached to the packing material. VOCs concentration detectors are installed at the air inlet, the two adjacent adsorption catalytic reaction zones, and the air outlet. Microwave feeding devices are provided on both sides of the first adsorption catalytic reaction zone and the second adsorption catalytic reaction zone. On the same side, two adjacent microwave feeding devices are orthogonally arranged. The cross-section of the terminal catalytic oxidation reaction zone perpendicular to the direction of waste gas flow is circular, and the microwave feed device is installed in a tangential microwave feed manner. Temperature sensors are installed in different areas of the first and second adsorption catalytic reaction zones; The packing material in the terminal catalytic oxidation zone is a glass fiber corrugated structure packing material coated with a microwave-absorbing catalyst; The processing method using this processing device includes the following steps: When the VOCs concentration in the waste gas to be treated is higher than the emission standard limit, the waste gas is introduced from the inlet and enters the adsorption-catalytic reaction zone for adsorption under the rectification and distribution of the airflow rectification and distribution structure. The gas purified by adsorption is discharged from the outlet. When the concentration of VOCs in the exhaust gas exceeds the set value, the adsorption catalyst regeneration process is activated, and the inlet flow rate of the exhaust gas is reduced to serve as the exhaust gas carrier gas. First, start the microwave feed device of the terminal catalytic oxidation reaction zone to heat it to the catalytic decomposition temperature of VOCs and above; then turn on the microwave feed device of the first adsorption catalytic reaction zone and / or the second adsorption catalytic reaction zone to heat the inside, so that the VOCs adsorbed on the adsorption catalyst are desorbed and catalytically degraded in situ. At the same time, the waste gas carrier gas carries out the degraded gas, and the VOCs in the waste gas carrier gas are catalytically degraded by the adsorption catalyst. During the regeneration process, the airflow rectification and distribution structure distributes the waste gas carrier gas in the cross-sectional direction, so that the temperature of the adsorbed catalyst is evenly distributed in the cross-sectional direction. The inlet flow rate of the exhaust gas during the regeneration process is 1 / 20 to 1 / 5 of the inlet flow rate of the exhaust gas during the adsorption process.

2. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 1, characterized in that: The blade shaft is located on the central axis of the blade body; Alternatively, the cross-section of the integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device is rectangular; Alternatively, the blade body may be rectangular; Alternatively, several airflow regulating blades may be evenly arranged along a cross-section perpendicular to the direction of exhaust gas flow. Alternatively, when each blade body is perpendicular to the exhaust gas flow direction, it covers at least 1 / 2 of the cross-sectional area of ​​the device.

3. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 1, characterized in that: The air inlet is an expanded diameter structure along the direction of exhaust gas flow; the air outlet is a contracted diameter structure along the direction of exhaust gas flow. Alternatively, the packing material in the adsorption catalytic zone may be a corrugated glass fiber packing material coated with an adsorption catalyst. The temperature sensor is a glass fiber thermometer or a sheathed thermocouple.

4. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 3, characterized in that: It also includes a controller, which is used to connect to the various temperature sensors, VOCs concentration detectors, drive motors and microwave feed devices.

5. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 1, characterized in that: During the regeneration process, the first adsorption catalytic reaction zone is regenerated first, and after the regeneration is completed, its microwave feed device is turned off; then the second adsorption catalytic reaction zone is regenerated, and after the regeneration is completed, its microwave feed device is turned off, and at the same time, the microwave feed device of the terminal catalytic oxidation reaction zone is turned off. Alternatively, during the adsorption stage, the angle of the blade body of the airflow rectification and distribution structure is adjusted so that the airflow channel in the central area is smaller than the airflow channels on both sides.

6. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 1, characterized in that: The adsorption catalyst comprises an adsorbent and a catalyst active component supported on the surface of the adsorbent. The loading of the catalyst active component is 10-30 wt%. The adsorbent is a zeolite molecular sieve, and the catalyst active component is FeMnCeO. x Graphene-doped manganese oxide or Co3O4-MnO2-CuO composite catalyst; in the graphene-doped manganese oxide, the doping amount of graphene is 0.5~8wt%.

7. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 6, characterized in that: The adsorbent is selected from at least one of 13X, MCM 41, ZSM-5, NaY, USY, HY, and Beta molecular sieves.

8. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 6, characterized in that: The adsorbent is a hydrophobic molecular sieve Beta-USY composite molecular sieve, with a mass ratio of Beta to USY phases of 1:9 to 9:

1.

9. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 6, characterized in that: In graphene-doped manganese oxides, the doping amount of graphene is 4~7wt%.

10. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 6, characterized in that: In the adsorption catalyst, the loading of the catalyst active component on the adsorbent is 10~20wt%.

11. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 6, characterized in that: The adsorption catalyst is 15-6-GO / MnO2@UB50, where 15 represents the GO / MnO2 loading on the UB50 molecular sieve as 15wt%, and 6 represents the graphene doping rate of 6wt% in the graphene-doped manganese oxide composite catalyst GO / MnO2.

12. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 6, characterized in that: The adsorption catalyst is 20% Fe. 0.85 -Mn 0.1 -Ce 0.05 @UB50, where 20% is the loading of the catalyst active component on the adsorbent.

13. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 1, characterized in that: When the concentration of VOCs in the waste gas to be treated is higher than the set value, the catalyst packing is heated to 200~300℃ by microwave, and the VOCs in the waste gas to be treated undergo direct catalytic oxidation and decomposition on the catalyst surface.

14. The integrated VOCs adsorption-desorption-in-situ catalytic oxidation treatment device according to claim 13, characterized in that: When the exothermic reaction from catalytic oxidation is sufficient to maintain the bed temperature, the microwave is turned off; when the temperature of the catalyst packing drops due to fluctuations in the VOCs concentration in the exhaust gas, the microwave is automatically turned on for auxiliary heating.

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