Low-carbon type VOCs adsorption concentration catalytic oxidation device and method

Abstract

This invention discloses a low-carbon VOCs adsorption, concentration, and catalytic oxidation device and method, comprising a hydrophobic multi-level porous molecular sieve processed into a disc shape as a rotating moving bed. The rotating moving bed is used to adsorb VOCs in a large volume of low-concentration waste gas, and then directly contacts high-temperature air at a temperature of 220-250°C for mass transfer, desorbing the VOCs into the high-temperature air. The resulting waste gas containing high concentrations of VOCs is sent to a dual-bed catalytic oxidation reactor to oxidize and purify the VOCs, and then discharged as high-temperature purified gas. The high-temperature purified gas is heated by a three-stage heat exchanger to desorb the VOCs from the multi-level porous molecular sieve. The rotating moving bed can adsorb and concentrate VOCs by 15-25 times. The transition bimetallic catalyst in the catalytic oxidation reactor has both adsorption and catalytic functions. This invention fully recovers and utilizes the heat generated by the catalytic oxidation of VOCs, eliminating the need for additional fuel to heat the waste gas for VOCs desorption, and realizing the self-heating catalytic oxidation of waste gas throughout the entire process.

Description

Technical Field

[0001] This invention relates to the fields of air pollution control and energy conservation and low-carbon technology, specifically to a low-carbon industrial VOCs adsorption, concentration, and catalytic oxidation device and process with adaptive adjustment function. Through three-stage waste heat recovery, system self-heating optimization, and low-temperature catalytic coupling, it achieves synergistic effects of efficient VOCs treatment and deep carbon reduction. It is particularly suitable for the efficient purification and low-carbon treatment of large-volume, low-concentration, and complex-component VOCs waste gas generated in industries such as coating, printing, chemical, and pharmaceutical. Background Technology

[0002] Volatile organic compounds (VOCs) are key precursors to the formation of ozone (O3) and fine particulate matter (PM2.5), and are also core pollutants controlled in air pollution prevention and control. Industries such as petrochemicals, coating, printing, and pharmaceuticals commonly exhibit VOC emissions characterized by large volumes, low to medium concentrations, high humidity, and complex compositions. Directly using catalytic oxidation processes would result in extremely high energy consumption and operating costs due to the large flow rate, low temperature, and low concentration of these gases, completely failing to meet the low-carbon and environmental protection requirements under the "dual carbon" goal.

[0003] Currently, zeolite rotor adsorption concentration + catalytic oxidation is the mainstream technical route for treating large volume, low concentration VOCs waste gas. Its core principle is to concentrate large volume, low concentration VOCs into small volume, high concentration waste gas through zeolite rotor, and then send it into catalytic oxidation furnace for high-temperature decomposition. However, the existing process has four major technical pain points, which seriously restrict its low-carbon application: (1) The waste heat recovery efficiency is extremely low: the high temperature purification gas above 400°C generated by the catalytic oxidation furnace is only preheated by a single-stage heat exchanger, and a large amount of waste heat is directly discharged, resulting in serious energy waste and a system thermal efficiency of less than 60%; (2) The system energy consumption and carbon emissions remain high: in order to maintain the reaction temperature of 300~400°C in the catalytic oxidation furnace, a large amount of natural gas, electricity and other external heating sources need to be continuously added, and the operating cost accounts for more than 70%, which directly leads to a surge in carbon emissions during the treatment process; (3) The process adaptability and stability are poor: the existing process does not optimize the waste heat distribution for the fluctuation of waste gas concentration and air volume, and is prone to the problem of "excessive waste heat in high concentration conditions and insufficient heat in low concentration conditions", the system has weak anti-fluctuation ability and poor operating stability; (4) The catalyst is expensive and easily deactivated: traditional processes mostly use Pt / Pd Precious metal catalysts have high procurement costs, high catalyst operating temperatures (350-450℃), and are easily affected by impurities in the exhaust gas, resulting in poisoning and deactivation. The catalyst has a short service life and needs to be replaced frequently, which greatly increases the equipment operation and maintenance costs. (5) Low level of intelligence: The equipment operation mainly relies on manual adjustment, and the response to changes in operating parameters such as VOCs concentration and temperature is lagging behind. It is easy to cause problems such as fluctuations in treatment efficiency and sudden increases in energy consumption, making it difficult to achieve stable operation. (6) Inadequate safety protection and potential operation hazards: There is a lack of perfect online monitoring and safety interlocking mechanisms. When the exhaust gas concentration changes suddenly or the system temperature is abnormal, it is easy to cause safety accidents such as fire and explosion. The safety and reliability of the equipment operation are insufficient.

[0004] To address the aforementioned shortcomings, although some technologies have attempted to optimize waste heat recovery, they have not yet broken through the core bottleneck of "single-stage heat exchange and dependence on external heat," failing to achieve end-to-end self-heating and deep carbon reduction. Therefore, developing a low-carbon VOCs adsorption, concentration, and catalytic oxidation process that enables efficient staged waste heat recovery, system self-heating operation, and long catalyst life has become a key technical challenge urgently needing to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned shortcomings of the prior art and provide a low-carbon industrial VOCs adsorption, concentration, and catalytic oxidation device. This device utilizes a multi-stage porous molecular sieve moving bed for high-rate concentration, three-stage waste heat recovery, precise temperature-controlled desorption, and low-temperature dual-bed catalytic oxidation. It addresses the pain points of traditional processes, such as low waste heat recovery efficiency, high system energy consumption, high carbon emissions, and easy catalyst deactivation. This achieves efficient purification of large volumes of medium-to-low concentration VOCs waste gas, deep energy saving and carbon reduction, and stable operation, helping industrial enterprises achieve "synergistic efficiency improvement through pollution reduction and carbon reduction."

[0006] The technical solution of this invention is a low-carbon VOCs adsorption, concentration, and catalytic oxidation method, comprising the following steps: Step S1: The cooled adsorbent comes into contact with the room temperature waste gas containing low concentrations of VOCs, transferring the VOCs into the adsorbent. The waste gas is then purified and discharged directly. Step S2: Use hot air to contact the rotating low-temperature adsorbent that adsorbs VOCs through mass transfer, transfer the VOCs into the hot air, and obtain waste gas containing high concentrations of VOCs at 220~230℃ and a thermal adsorbent for desorbing VOCs. Step S3: The waste gas containing high concentrations of VOCs is fed into two fixed beds connected in series in the catalytic oxidation reactor. In the first fixed bed, mass transfer occurs with the Fe1Mn2 / Al2O3 catalyst, which adsorbs VOCs and oxidizes them into CO2 and H2O, releasing heat and producing high-temperature waste gas. The Fe1Mn2 / Al2O3 catalyst in the second fixed bed reacts with the residual VOCs from the first fixed bed, and the high-temperature waste gas is converted into high-temperature purified gas with a temperature of not less than 400℃. At the same time, the carbon deposits in the Fe1Mn2 / Al2O3 catalyst in the second fixed bed are removed. Step S4: The high-temperature purified air with a temperature not lower than 400℃ is subjected to low-temperature waste heat recovery and heat exchange with preheated air in a heat exchanger to heat the preheated air to 220~230℃ hot air. Step S5: After VOCs are desorbed, the adsorbent is directly heated with room temperature air to preheat the air to 60~80℃, while the adsorbent itself is cooled to below 40℃. Step S6: After cooling, the adsorbent continues to rotate until it can contact the room-temperature waste gas containing low concentrations of VOCs, and continues to cycle according to the above steps S1-S5. The adsorbent is a disc-shaped rotating moving bed made of hydrophobic hierarchical porous zeolite molecular sieve.

[0007] Furthermore, the two fixed beds connected in series in the catalytic oxidation reactor exchange the order in which they first come into contact with the waste gas containing high concentrations of VOCs according to a preset cycle, and the volume of the waste gas to be treated at room temperature is at least 15 times that of room temperature air.

[0008] The technical solution of the present invention also includes a VOCs adsorption, concentration, and catalytic oxidation device, comprising an adsorbent / desorber, which is a disc-shaped shell. A rotating moving bed rotatable around a central axis is provided inside the disc-shaped shell. The rotating moving bed is a hydrophobic zeolite molecular sieve processed into a disc shape. Three spacers are provided on the inner wall of the disc-shaped shell, extending radially from the center of the front disc surface to the center of the rear disc surface. All three spacers are in frictional contact with the rotating moving bed, dividing the disc cavity of the disc-shaped shell into three sector-shaped regions along its circumference. Inlet ventilation pipes and outlet ventilation pipes are respectively provided on the front disc surfaces of the disc-shaped shell on the front and rear sides of the three sector-shaped regions. The three sector-shaped regions include a third sector-shaped region, a first sector-shaped region, and a second sector-shaped region. A dust filter, a demisting and dehumidifying unit, and an exhaust gas treatment fan are connected in series between the inlet ventilation pipe of the three sector-shaped zone and the exhaust gas inlet of the VOCs adsorption, concentration, and catalytic oxidation unit. The outlet ventilation pipe of the third sector-shaped zone of the adsorption-desorber is connected to the atmosphere, and the outlet duct of the air blower is connected to the inlet ventilation pipe of the first sector-shaped zone of the adsorption-desorber. The outlet ventilation pipe of the first sector-shaped zone of the adsorption-desorber is connected to the inlet ventilation pipe of the second sector-shaped zone of the adsorption-desorber through a pipe connected to the first medium channel of the heat exchanger. The outlet ventilation pipe of the second sector-shaped zone is connected to the main inlet pipe of the catalytic oxidation reactor, and the exhaust pipe of the catalytic oxidation reactor is connected to the second medium channel of the heat exchanger. Finally, the purified gas after heat exchange is discharged to the atmosphere. The catalytic oxidation reactor is filled with a catalyst for the degradation and oxidation of VOCs.

[0009] Furthermore, the catalytic oxidation reactor includes two vertical cylindrical fixed beds. Each fixed bed has an independent inlet branch pipe at its bottom, and the two inlet branch pipes and the main inlet pipe are connected by a two-position three-way directional valve. Each fixed bed has an independent exhaust branch pipe on its lower side wall, and the two exhaust branch pipes and the main exhaust pipe are connected by a two-position three-way directional valve. The tops of the two fixed beds are directly connected. The upper layer of each fixed bed is filled with a low-temperature Fe1Mn2 / Al2O3 catalyst bed, and the lower layer is filled with a porous alumina molecular sieve protective layer. Two-position three-way directional valves one and two-position three-way directional valves two are used. The exhaust gas flow from the intake manifold to the exhaust manifold is controlled to pass sequentially through two fixed beds connected in series. The two fixed beds periodically exchange the order in which the exhaust gas flow passes. The fixed bed that first exchanges mass with the exhaust gas acts as a reaction bed, adsorbing VOCs from the exhaust gas flow and oxidizing them into CO2 and H2O, releasing heat and purifying the exhaust gas flow. The fixed bed that then exchanges mass with the purified exhaust gas flow acts as a regeneration bed, using the high-temperature purified exhaust gas flow to remove the carbon on the catalyst surface and the adsorbed CO2 and H2O. The temperature of the regeneration bed drops to restore the catalyst activity.

[0010] Furthermore, the Fe1Mn2 / Al2O3 low-temperature catalyst is prepared by impregnation using 40-60 mesh porous alumina as a support. The preparation steps are as follows: (2) Immerse the porous alumina in the mixed metal salt solution for 12-24 hours; (3) Dry the impregnated porous alumina carrier in an oven at 100℃±5℃ for 10-12 hours; (4) The dried porous alumina loaded with iron and manganese bimetallic metals was calcined in a muffle furnace at 500℃±5℃ for 3-5 hours to obtain the primary product of the catalyst. (5) The primary product of the catalyst is compressed and molded in a molding die to prepare the final product of the honeycomb-shaped Fe1Mn2 / Al2O3 low-temperature catalyst. Further, the hydrophobic zeolite molecular sieve adsorbent is a silanized modified NaY type honeycomb zeolite molecular sieve with a temperature resistance ≥550℃, a moisture absorption rate <3%, a VOCs static adsorption capacity ≥220mg / g, and an adsorption capacity decay rate ≤10% in the relative humidity range of 0~90%RH; the areas of the first sector, the second sector, and the third sector account for 70%, 15%, and 15% of the rotating moving bed, respectively.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention relates to a VOCs adsorption, concentration, and catalytic oxidation device and method, which effectively addresses the technical pain points of traditional VOCs treatment equipment, such as high desorption energy consumption, easy catalyst deactivation, low waste heat utilization rate, and insufficient safety protection. It achieves synergistic effects in pollution reduction and carbon reduction, with the following comprehensive beneficial results: 1. High purification efficiency and strong adaptability to operating conditions: Utilizing a combination of Fe1Mn2 / Al2O3 low-temperature catalyst and hydrophobic zeolite molecular sieve, coupled with a dual fixed-bed alternating operation structure, it exhibits excellent degradation effects on both single and complex VOC components, with an inlet concentration of 80~120 mg / m³. 3 With a removal rate of ≥98%, and no significant attenuation of adsorbent and catalyst activity under high humidity conditions, this invention is suitable for the treatment needs of large-volume, low-concentration, and high-humidity VOCs in various industries such as coating, chemical, and pharmaceutical. The Fe1Mn2 / Al2O3 low-temperature catalyst, using porous alumina as a carrier, is inexpensive and readily available. Furthermore, the Fe1Mn2 / Al2O3 catalyst plays a secondary role in capturing or storing VOCs molecules in the catalytic oxidation reactor, avoiding escape problems caused by fluctuations in VOCs concentration. This invention breaks through the technical bottleneck of traditional single-stage heat exchange, using the 400-450℃ high-temperature hot gas generated by catalytic oxidation in three stages for waste heat power generation, preheating desorbed gas, and supplementing heat in the desorption zone, respectively. Waste heat recovery efficiency is increased to over 92%, and the system's self-heating rate reaches 100%, completely eliminating dependence on external heating sources. Compared to traditional processes, energy consumption is reduced by over 60%, operating costs are reduced by 70%, and the investment payback period is only 1.5 years, demonstrating excellent economic efficiency.

[0012] 2. Significant low-carbon and energy-saving effects: The dual independent gas path circulation design achieves closed-loop heat circulation. Combined with the alternating operation logic of dual fixed beds, the clean, high-temperature purified gas that generates its own heat from catalytic oxidation serves as the desorption heat source (and also as the regeneration purge gas for both beds). No external regeneration heat source or purge medium is required. The cascade waste heat recovery efficiency is ≥92%, and more than 88% of the desorption heat comes from the system's own heat release. The energy consumption per unit air volume is only 0.08 kW·h / 1000m³. 3 Compared to traditional equipment, this method reduces energy consumption and carbon emissions by 68%, significantly decreasing the need for auxiliary heating. It utilizes the heat generated from the catalytic oxidation of VOCs to heat the gas used for VOCs desorption, eliminating the need for additional fuel to heat the gas and achieving fully autothermal catalytic oxidation.

[0013] 3. Stable operation and long service life: The Fe1Mn2 / Al2O3 low-temperature catalyst has an ignition temperature of ≤200℃, and continuous operation under high space velocity and high humidity conditions shows no activity decay, with a cost of only 1 / 5 of that of precious metal catalysts; the dual-catalyst bed alternating reaction-regeneration design can remove carbon deposits on the catalyst surface in real time, completely avoiding catalyst deactivation due to carbon buildup. Compared with single-bed devices, the catalyst activity retention rate is increased by more than 30%, and the continuous operation capability is increased by more than 3 times; the hydrophobic molecular sieve, after modification, has excellent temperature resistance and moisture resistance, and its performance retention rate is high after multiple adsorption-desorption cycles, making the core components of the device suitable for long-term continuous industrial operation.

[0014] 4. The rotary moving bed concentration has a significantly higher concentration ratio than traditional adsorbers (up to 20 times or more), reducing the volume of large-volume waste gas by more than 20 times and increasing the concentration of waste gas by more than 20 times. The combined process of rotary moving bed adsorption and low-temperature dual-bed two-stage catalytic oxidation achieves a total VOCs removal rate of ≥99%, and the concentration of non-methane total hydrocarbons in the purified waste gas is ≤10mg / m³. 3 It stably meets national and local emission standards; through the intelligent control system, it can adapt to VOCs exhaust gas conditions with different air volume, concentration and humidity, with strong anti-fluctuation ability and high operational stability. 5. The multi-stage porous molecular sieve in the rotating moving bed can be used for different types and molecular weights of VOCs, improving the adaptability of the whole process and expanding its application range; 6. Without adding new core large-scale equipment, technological breakthroughs can be achieved through process route optimization, waste heat utilization, and catalyst upgrading. The investment cost is only 5% to 10% higher than that of traditional processes, but the operating cost is significantly reduced, the investment payback period is short, it is compatible with the transformation and upgrading of existing equipment, and the prospects for promotion and application are broad. Attached Figure Description

[0015] Figure 1 It is the core laboratory device for testing the catalytic oxidation performance of VOCs; Figure 2The pore structure characteristics of the porous FexMny / Al2O3 series catalysts are shown in (a) the nitrogen adsorption-desorption isotherm and (b) the pore size distribution curve. Figure 3 XRD patterns of porous FexMny / Al2O3 series catalysts; Figure 4 SEM and TEM images of the Fe1Mn2 / Al2O3 catalyst in the porous FexMny / Al2O3 series catalysts; Figure 5 XPS analysis results for porous FexMny / Al2O3 series catalysts; Figure 6 The image shows the H2-TPR (hydrogen temperature programmed reduction) spectrum of porous FexMny / Al2O3 series catalysts. Figure 7 The adsorption performance of porous FexMny / Al2O3 series catalysts on toluene is shown in (a) the dynamic adsorption breakthrough curve of toluene and (b) the relationship between toluene adsorption capacity and BET specific surface area. Figure 8 The activity of porous FexMny / Al2O3 series catalysts for the catalytic oxidation of toluene is shown in (a) the conversion curve of toluene catalytic oxidation and (b) the CO2 selectivity curve. Figure 9 Stability evaluation of Fe1Mn2 / Al2O3 catalysts in the porous FexMny / Al2O3 series catalysts; Figure 10 This is a flowchart of the process for a low-carbon industrial VOCs adsorption, concentration, and catalytic oxidation device. Detailed Implementation

[0016] The specific embodiments and working process of the present invention will be further described below with reference to the accompanying drawings. Example 1

[0017] This embodiment discloses porous Fe x The preparation steps, structural characterization, and performance testing of the Mnᵧ / Al2O3 catalyst were investigated, and the optimal ratio of Fe1Mn2 / Al2O3 was determined, providing a core low-temperature catalytic component for the device.

[0018] 1.1 Porous Fe x Mn y Preparation of Al2O3 catalyst (1) Prepare the solution. Based on the target design of the Fe to Mn molar ratio (1:0, 0:1, 1:1, 2:1, 1:2, 3:1), calculate the required mass of iron source (Fe(NO3)3·9H2O) and manganese source (Mn(CH3COO)2·4H2O) respectively, and accurately weigh the above metal salts. Dissolve the weighed iron salt and manganese salt together in deionized water and stir until completely clear to prepare a mixed metal salt solution.

[0019] (2) Impregnation: Immerse the porous alumina carrier with a pore size of 40-60 mesh in the solution for 12-24 hours to allow the metal components to be fully adsorbed into the pores of the carrier.

[0020] (3) Drying: Take out the impregnated carrier and dry it in an oven at about 100°C for 10-12 hours to remove moisture.

[0021] (4) Calcination: The dried sample is placed in a muffle furnace for high-temperature calcination at approximately 500°C for 3-5 hours to convert the metal into an active oxide, thus obtaining the finished product. This promotes strong interactions between Fe and Mn oxides and the Al2O3 support, resulting in abundant lattice oxygen and high-valence metal ions (Fe2O3). 3、 ,Mn 4、 ) Active site.

[0022] 1.2 Catalyst Performance Testing Device The experimental device for testing the catalytic oxidation performance of VOCs consists of a gas distribution and intake unit, a reaction unit, and a detection and control unit.

[0023] (1) Gas preparation and injection: The flow rates of carrier gas N2 and O2 are precisely controlled by mass flow controller (MFC), and toluene is introduced by micro-injection pump or bubbling method to prepare simulated industrial VOCs waste gas of different concentrations.

[0024] (2) Temperature-controlled reaction: The waste gas is preheated before entering the container filled with Fe. x The quartz tube reactor with Mnᵧ / Al2O3 catalyst undergoes catalytic oxidation in a tubular furnace. The device achieves automated control of temperature and flow rate through a programmed temperature controller (PTC) and a multi-channel temperature controller (TC), controlling the temperature at 200-400℃ to meet the low-temperature catalytic requirements of industrial equipment.

[0025] (3) Detection and collection: The gas after the reaction is analyzed online by gas chromatograph (GC) to calculate the toluene conversion rate and CO2 selectivity.

[0026] 1.3 Porous Fe x Mn y Performance testing of Al2O3 series catalysts.

[0027] (1) Pore structure properties: by Figure 2 It can be seen that the introduction of Mn effectively inhibits the aggregation of metal oxides and optimizes the pore structure of the support. With the increase of the Mn / Fe stoichiometric ratio, Fe... x The Mnᵧ / Al2O3 catalyst exhibits increased specific surface area and pore volume, with Fe1Mn3 / Al2O3 possessing the highest specific surface area and largest pore volume, which is beneficial for mass transfer of reactants and exposure of active sites.

[0028] (2) Crystal structure properties, Figure 3 It is Fe x X-ray diffraction (XRD) patterns of the Mnᵧ / Al₂O₃ series catalysts showed that all samples exhibited a stable γ-Al₂O₃ support structure. Clear Fe₂O₃ crystalline phase peaks were observed in the pure Fe / Al₂O₃ samples, while increasing the Mn content effectively suppressed Fe₂O₃ crystal growth and promoted high dispersion of iron species. Simultaneously, Mn oxides were uniformly distributed on the support surface in amorphous or ultrafine grain form, constructing abundant surface active sites and open porous structures, thus enhancing low-temperature catalytic oxidation performance.

[0029] (3) Microscopic morphology, Figure 4 The microstructure and crystal structure of the Fe1Mn2 / Al2O3 catalyst are shown, indicating that the Fe1Mn2 / Al2O3 catalyst exhibits a porous aggregate structure, with metal oxides uniformly distributed on the surface of the Al2O3 support in the form of nanoparticles; α-Fe2O3 exists in the form of nanocrystals, constituting the main active center.

[0030] (4) Surface chemical properties, Figure 5 The X-ray photoelectron spectroscopy (XPS) results confirmed that the catalyst surface was loaded with elements such as Fe, Mn, O, and Al, with Fe mainly in the form of Fe2+. 3+ It exists in the form of a small amount of Fe. 2+ It facilitates the formation of oxygen vacancies; Mn as Mn 3+ and Mn 4+ Mixed valence states exist, and oxygen species (O) are adsorbed on the Fe1Mn3 / Al2O3 surface. a d s () has the highest proportion.

[0031] (5) Redox properties, by Figure 6 The H2-TPR results show that with increasing Mn content, Fe... x Mn y The reduction peak of the / Al2O3 catalyst shifts towards lower temperatures. Fe1Mn3 / Al2O3 shows significant low-temperature reduction peaks at 248°C and 298°C, indicating a significant improvement in the redox performance of the catalyst.

[0032] (6) Adsorption performance, such as Figure 7 As shown, the dynamic adsorption breakthrough curve (a) and the correlation diagram of toluene adsorption capacity (b) of toluene demonstrate that the Fe1Mn3 / Al2O3 catalyst has the shortest dynamic adsorption duration for toluene and a static adsorption capacity of 79 mg / g, indicating that it has the ability to adsorb toluene.

[0033] (7) Core performance of catalytic oxidation, such as Figure 8 As shown, the Fe1Mn2 / Al2O3 catalyst exhibits the best low-temperature catalytic activity and CO2 selectivity, with both toluene conversion and CO2 selectivity approaching 100% at 240℃. 90 At approximately 230℃, it is significantly superior to other formulations and single-metal catalysts, enabling efficient and complete mineralization of toluene at low temperatures.

[0034] (8) Stability and moisture resistance, such as Figure 9 As shown, at 250℃ and a volumetric hourly space velocity of 80000 mL·g -1 ·h -1 Under high air velocity conditions, the Fe1Mn2 / Al2O3 catalyst maintained a stable toluene conversion rate of 100% throughout a 60-hour continuous operation test. After switching to a high-humidity atmosphere of 50% relative humidity for 25–50 hours, the catalyst activity showed no decline and remained stable even after returning to a dry atmosphere. These results indicate that the Fe1Mn2 / Al2O3 catalyst possesses excellent long-term stability and moisture resistance. Example 2

[0035] This embodiment describes a VOCs adsorption, concentration, and catalytic oxidation device. The overall structure, process flow, selection of core components, and operating parameters of the device are described in detail. Those skilled in the art can fully reproduce the device of the present invention based on this embodiment.

[0036] 1. Overall structure of the device like Figure 10As shown, the VOCs adsorption, concentration, and catalytic oxidation device of the present invention includes: an adsorbent / desorber 5, which is a disc-shaped shell. The disc cavity of the disc-shaped shell is divided into three sector-shaped areas along the circumference. A rotating moving bed that can rotate around the central axis is provided inside the disc-shaped shell. The rotating moving bed is a hydrophobic zeolite molecular sieve processed into a disc shape. Three partitions are provided on the inner wall of the disc-shaped shell, extending radially from the center of the front disc surface to the center of the rear disc surface. All three partitions are in frictional contact with the rotating moving bed, dividing the disc cavity of the disc-shaped shell into three sector-shaped areas along the circumference. An inlet ventilation pipe and an outlet ventilation pipe are respectively provided on the front disc surface of the disc-shaped shell on the front and rear sides of the three sector-shaped areas. The three sector-shaped areas include a first sector-shaped area 51, a second sector-shaped area 52, and a third sector-shaped area 53, which correspond to the cooling zone, the desorption zone, and the adsorption zone, respectively. The inlet ventilation pipe of the third sector 53 of the adsorption-desorber 5 is connected to the outlet of the exhaust gas treatment fan 1 of the low-carbon industrial VOCs adsorption concentration catalytic oxidation device; the outlet ventilation pipe of the third sector 53 of the adsorption-desorber 5 is connected to the atmosphere, and the outlet duct of the air blower 2 is connected to the inlet ventilation pipe of the first sector 51 of the adsorption-desorber 5; the outlet ventilation pipe of the first sector 51 of the adsorption-desorber 5 is connected to the inlet ventilation pipe of the second sector 52 of the adsorption-desorber 5 through a pipe that connects the first medium channel of the heat exchanger 6 in series; the outlet ventilation pipe of the second sector 52 of the adsorption-desorber 5 is connected to the main inlet pipe of the catalytic oxidation reactor 9; the exhaust pipe of the catalytic oxidation reactor 9 is connected to the waste heat boiler recovery unit 4 and the second medium channel of the heat exchanger 6; and finally, the purified gas after heat exchange is discharged to the atmosphere.

[0037] The catalytic oxidation reactor 9 includes two vertical cylindrical fixed beds. Each fixed bed has an independent air inlet branch pipe at its bottom. The two air inlet branch pipes and the main air inlet pipe are connected by a two-position three-way reversing valve. Each fixed bed has an independent exhaust branch pipe on its lower side wall. The two exhaust branch pipes and the main exhaust pipe are connected by a two-position three-way reversing valve. The tops of the two fixed beds are directly connected to form a common gas buffer chamber for uniformly collecting high-temperature purified gas. The upper layer of each fixed bed is filled with the low-temperature Fe1Mn2 / Al2O3 catalyst bed 92 of Example 1, and the lower layer is filled with a porous alumina molecular sieve protective layer 91. The two form a functionally layered and synergistically enhanced double-layer bed structure. Two-position three-way directional valves one and two-position three-way directional valves two are controlled, causing the exhaust gas flow from the intake manifold to the exhaust manifold to pass sequentially through two fixed beds connected in series. The two fixed beds periodically change the order in which the exhaust gas flow passes through them. The first fixed bed first undergoes mass exchange with the exhaust gas flow, acting as a reaction bed. It first adsorbs VOCs from the exhaust gas flow and continuously oxidizes them into CO2 and H2O, releasing heat. The exhaust gas flow temperature rises from 220~230℃ to 220-300℃, achieving low-temperature and high-efficiency oxidation, purifying the exhaust gas flow, with a toluene conversion rate ≥99%, and catalytic oxidation. The heat generated during the oxidation process is transferred to the porous alumina molecular sieve protective layer 91 for heat storage; after the second fixed bed, it undergoes gas-flow mass exchange with the purified waste gas, serving as a regeneration bed. Before becoming a regeneration bed, the second fixed bed has already acted as a reaction bed for catalytic oxidation and heat storage, containing residual VOCs and carbon deposits from the reaction. The residual VOCs in the high-temperature purified waste gas react with the catalyst, releasing heat and catalytic combustion. The airflow carries away the carbon deposits and adsorbed CO2 and H2O from the catalyst surface. After the high-temperature purified waste gas is heated to 400-500℃, the regeneration bed restores the catalyst activity. Figure 10 As shown, the dual fixed bed achieves alternating reaction-regeneration operation through two-position three-way reversing valve one and two-position three-way reversing valve two, with the reaction bed providing a stable backflush gas source for the regeneration bed.

[0038] The lower porous alumina molecular sieve protective layer 91 of the fixed bed has a pore size gradient distribution. From the lower gas inlet end to the upper catalyst bed end, the pore size decreases from large to small. It serves as a heat storage body to buffer temperature fluctuations and prevents radial concentration / temperature imbalance through uniform airflow. This achieves uniform airflow and temperature buffering, which improves the utilization rate of catalyst active sites by more than 30%. The dual-bed alternating regeneration avoids catalyst carbon deposition and deactivation, ensuring that the long-term operation of the catalyst has an activity retention rate of ≥88% and a stable catalytic oxidation efficiency of more than 98%.

[0039] Specifically, directional valve one has two valve positions, V1 and V2. When the valve core is in position V1, the main intake pipe is connected to the intake branch pipe of fixed bed A and disconnected from the bottom intake branch pipe of fixed bed B. When the valve core is in position V2, the main intake pipe is connected to the intake branch pipe of fixed bed B and disconnected from the bottom intake branch pipe of fixed bed A. directional valve two has two valve positions, V3 and V4. When the valve core is in position V3, the exhaust branch pipe of fixed bed A is connected to the main exhaust pipe and disconnected from the main exhaust pipe of fixed bed B. When the valve core is in position V4, the exhaust branch pipe of fixed bed B is connected to the main exhaust pipe and disconnected from the main exhaust pipe of fixed bed A. When directional valve one and directional valve two are operated, only valve positions V1 and V4, or valve positions V2 and V3, are allowed to occur simultaneously.

[0040] The hydrophobic zeolite molecular sieve is a honeycomb structure formed by pressing hydrophobic zeolite of aluminosilicate. It has a temperature resistance of ≥500℃, a moisture absorption rate of <3%, and a VOCs adsorption capacity of ≥200mg / g. The areas of the third sector 53, the first sector 51, and the second sector 52 account for 70%, 15%, and 15% of the rotary moving bed, respectively. The third sector 53 treats low-concentration waste gas at room temperature for VOCs adsorption, the first sector 51 is introduced with room temperature air for cooling and desorption of VOCs, and the second sector 52 is introduced with high-temperature concentrated waste gas at 220℃ for oxidation. The rotary moving bed rotates horizontally around its central axis at a speed of 1-3 rpm, precisely controlled by a drive motor.

[0041] 2. VOCs adsorption, concentration, and catalytic oxidation methods, including: Exhaust gas treatment fan 1 treats ambient temperature exhaust gas containing low concentrations of VOCs (air volume 100,000 m³ / h). 3 / h, VOCs concentration 200-300mg / m³ 3 After dust and mist removal, the gas first comes into mass transfer contact with the rotating, heated adsorbent that desorbs VOCs, transferring the VOCs into the adsorbent to obtain purified exhaust gas (VOCs concentration ≤10mg / m³). 3 ) and discharge; The adsorbent then reacts with ambient temperature air (5000m³) delivered by air blower 2. 3(h) Heat transfer: At room temperature, the desorbed high-temperature adsorbent is cooled to 40-60℃, restoring its adsorption performance. During cooling, the room temperature air absorbs heat and rises to 60-80℃, forming medium-temperature air. The 400-450℃ high-temperature purified gas discharged from the catalytic oxidation reactor 9 enters the waste heat boiler recovery unit 4 to generate electricity, which is used to power the exhaust gas treatment fan 1, air blower 2, and system control unit. The temperature of the high-temperature purified gas drops to 250-270℃. The preheated medium-temperature air is sent to the heat exchanger 6 to absorb the heat from the 250-270℃ high-temperature purified gas discharged from the waste heat boiler recovery unit 4. Through efficient heat exchange, the medium-temperature air absorbs the heat from the high-temperature exhaust gas, rising to 220-230℃, forming high-temperature desorption air. This air then comes into mass transfer contact with the rotating, cooled adsorbent, transferring VOCs to the hot air for thermal desorption of the saturated adsorbent transferred from the adsorption zone. The adsorbent is desorbed, forming a small-volume, high-concentration concentrated waste gas (concentration increased by 15-25 times, air volume is 4%-10% of the original waste gas, 5000m³). 3 / h, 4000-6000mg / m 3 This process yields waste gas containing high concentrations of VOCs and an adsorbent for desorbing VOCs by heating. Waste gas containing high concentrations of VOCs is fed into catalytic oxidation reactor 9 to oxidize VOCs and release heat, thereby obtaining high-temperature purified gas; The high-temperature purified gas is discharged after exchanging heat with preheated air in the waste heat boiler recovery unit 4 and heat exchanger 6. The above process utilizes the heat generated by the catalytic oxidation of VOCs in the catalytic oxidation reactor 9 to heat the preheated air, supplementing the heat consumed by the adsorbent in the desorption of VOCs. The exhaust gas containing high concentrations of VOCs undergoes self-thermal catalytic oxidation, eliminating the need for additional fuel to heat the preheated air.

[0042] The adsorbent is a disc-shaped rotating moving bed made of hydrophobic zeolite molecular sieve. The rotating moving bed is installed in the disc cavity of the adsorbent-desorber 5 and rotates. When a portion of the honeycomb units in the rotating moving bed rotates to the third sector 53 of the adsorption-desorption unit 5, it adsorbs VOCs from the waste gas containing low concentrations of VOCs. This process removes most of the VOCs from the waste gas, achieving a removal rate >95% and an outlet concentration ≤20 mg / m³. 3 The rotating bed rotates continuously, and after the honeycomb unit is saturated with adsorption, it automatically moves into the first sector 51 to exchange heat with room temperature air, cools the saturated adsorbent, and maintains the stability of the adsorbent.

[0043] The high-temperature purified exhaust gas (400-500℃) from the exhaust pipe of the catalytic oxidation reactor 9 is directly transported to the waste heat recovery unit 4 to recover waste heat. Then, it exchanges heat with preheated air in the heat exchanger 6, heating the preheated air to 220-230℃. This hot air passes through the rotating honeycomb cells (52) of the adsorbent-desorber 5, where it transfers heat to the molecular sieve via solid-phase heat conduction. This causes the VOC molecules within the honeycomb cells to be thermally desorbed. After heating, the gas is cooled to 220℃, resulting in a medium-temperature tail gas containing a high concentration of VOCs. This tail gas is discharged from the other side of the adsorbent-desorber 5 and then returned to the inlet pipe of the catalytic oxidation reactor 9. The desorbed VOCs honeycomb cells then rotate to the third sector 53 of the adsorbent-desorber 5. The medium-temperature tail gas containing high concentrations of VOCs undergoes catalytic oxidation and exothermic reaction in the catalytic oxidation reactor 9, decomposing the VOCs.

[0044] The rotating moving bed rotates continuously at a constant speed (1-5 r / h), and the adsorbent in the adsorption zone, desorption zone and cooling zone circulates in sequence, realizing continuous operation of adsorption, desorption and cooling. The system does not need to be stopped for regeneration, ensuring continuous and stable operation.

[0045] 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. A low-carbon VOCs adsorption, concentration, and catalytic oxidation method, characterized in that, Includes the following steps: Step S1: The cooled adsorbent comes into contact with the room temperature waste gas containing low concentrations of VOCs, transferring the VOCs into the adsorbent. The waste gas is then purified and discharged directly. Step S2: Use hot air to contact the rotating low-temperature adsorbent that adsorbs VOCs through mass transfer, transfer the VOCs into the hot air, and obtain waste gas containing high concentrations of VOCs at 220~230℃ and a thermal adsorbent for desorbing VOCs. Step S3: The waste gas containing high concentrations of VOCs is fed into two fixed beds connected in series in the catalytic oxidation reactor. In the first fixed bed, mass transfer occurs with the Fe1Mn2 / Al2O3 catalyst, which adsorbs VOCs and oxidizes them into CO2 and H2O, releasing heat and producing high-temperature waste gas. The Fe1Mn2 / Al2O3 catalyst in the second fixed bed reacts with the residual VOCs from the first fixed bed, and the high-temperature waste gas is converted into high-temperature purified gas with a temperature of not less than 400℃. At the same time, the carbon deposits in the Fe1Mn2 / Al2O3 catalyst in the second fixed bed are removed. Step S4: The high-temperature purified air with a temperature not lower than 400℃ is subjected to low-temperature waste heat recovery and heat exchange with preheated air in a heat exchanger to heat the preheated air to 220~230℃ hot air. Step S5: After VOCs are desorbed, the adsorbent is directly heated with room temperature air to preheat the air to 60~80℃, while the adsorbent itself is cooled to below 40℃. Step S6: After cooling, the adsorbent continues to rotate until it can contact the room-temperature waste gas containing low concentrations of VOCs, and continues to cycle according to the above steps S1-S5. The adsorbent is a disc-shaped rotating moving bed made of hydrophobic hierarchical porous zeolite molecular sieve.

2. The VOCs adsorption, concentration, and catalytic oxidation method according to claim 1, characterized in that, In the catalytic oxidation reactor, two fixed beds connected in series exchange contact with the waste gas containing high concentrations of VOCs according to a preset cycle. The volume of the waste gas to be treated at room temperature is at least 15 times that of room temperature air.

3. The VOCs adsorption, concentration, and catalytic oxidation method according to claim 1, characterized in that, The Fe1Mn2 / Al2O3 low-temperature catalyst was prepared by impregnation using 40-60 mesh porous alumina as a support. The preparation steps are as follows: (1) Weigh ferric nitrate nonahydrate and manganese acetate tetrahydrate according to the Fe to Mn molar ratio of 1:2, and dissolve them together in deionized water to prepare a mixed metal salt solution; (2) Immerse the porous alumina in the mixed metal salt solution for 12-24 hours; (3) Dry the impregnated porous alumina carrier in an oven at 100℃±5℃ for 10-12 hours; (4) The dried porous alumina loaded with iron and manganese bimetallic metals was calcined in a muffle furnace at 500℃±5℃ for 3-5 hours to obtain the primary product of the catalyst. (5) The primary product of the catalyst is compressed and molded in a molding die to prepare the honeycomb-shaped final product of the Fe1Mn2 / Al2O3 low-temperature catalyst.

4. The VOCs adsorption, concentration, and catalytic oxidation method according to claim 1, characterized in that, The hydrophobic hierarchical porous zeolite molecular sieve adsorbent is a silanized modified NaY type honeycomb zeolite molecular sieve with a temperature resistance ≥550℃, a moisture absorption rate <3%, a static VOCs adsorption capacity ≥220mg / g, and an adsorption capacity decay rate ≤10% in the relative humidity range of 0~90%RH. The areas of the first sector, the second sector, and the third sector account for 70%, 15%, and 15% of the rotating moving bed, respectively.

5. A VOCs adsorption, concentration, and catalytic oxidation device, characterized in that, The device includes an adsorbent / desorber with a disc-shaped shell. Inside the disc-shaped shell is a rotating moving bed that can rotatably rotate around a central axis. The rotating moving bed is a hydrophobic zeolite molecular sieve machined into a disc shape. The inner wall of the disc-shaped shell has three spacers extending radially from the center of the front disc surface to the center of the rear disc surface. All three spacers are in frictional contact with the rotating moving bed, dividing the disc cavity of the disc-shaped shell into three sector-shaped regions along its circumference. Inlet and outlet ventilation pipes are respectively installed on the front disc surfaces of the disc-shaped shell on the front and rear sides of each sector-shaped region. The three sector-shaped regions are: a third sector-shaped region, a first sector-shaped region, and a second sector-shaped region. The inlet ventilation pipe of the third sector-shaped region of the adsorbent / desorber is connected to the VOCs adsorption and concentration system. A dust filter, a demisting and dehumidifying unit, and an exhaust gas treatment fan are connected in series between the exhaust gas inlets of the catalytic oxidation unit. The outlet ventilation pipe of the third sector of the adsorption-desorber is connected to the atmosphere, and the outlet duct of the air blower is connected to the inlet ventilation pipe of the first sector of the adsorption-desorber. The outlet ventilation pipe of the first sector of the adsorption-desorber is connected to the inlet ventilation pipe of the second sector of the adsorption-desorber through a pipe that connects to the first medium channel of the heat exchanger. The outlet ventilation pipe of the second sector is connected to the main inlet pipe of the catalytic oxidation reactor, and the exhaust pipe of the catalytic oxidation reactor is connected to the waste heat boiler recovery unit and the second medium channel of the heat exchanger. Finally, the purified gas after heat exchange is discharged to the atmosphere. The catalytic oxidation reactor is filled with a low-temperature Fe1Mn2 / Al2O3 catalyst for the degradation and oxidation of VOCs.

6. The VOCs adsorption, concentration, and catalytic oxidation device according to claim 4, characterized in that, The catalytic oxidation reactor comprises two vertical cylindrical fixed beds. Each fixed bed has an independent inlet branch pipe at its bottom, which is connected to the main inlet pipe via a two-position three-way directional valve. Each fixed bed also has an independent exhaust branch pipe on its lower sidewall, which is connected to the main exhaust pipe via a two-position three-way directional valve. The tops of the two fixed beds are directly connected. Each fixed bed has a low-temperature Fe1Mn2 / Al2O3 catalyst bed in its upper layer and a porous alumina molecular sieve protective layer in its lower layer. The two-position three-way directional valves are actuated. The exhaust gas flow from the intake manifold to the exhaust manifold passes sequentially through two fixed beds connected in series. The two fixed beds periodically exchange the order in which the exhaust gas flow passes. The fixed bed that first exchanges mass with the exhaust gas acts as a reaction bed, adsorbing VOCs from the exhaust gas flow and oxidizing them into CO2 and H2O, releasing heat and purifying the exhaust gas flow. The fixed bed that then exchanges mass with the purified exhaust gas flow acts as a regeneration bed, using the high-temperature purified exhaust gas flow to remove the carbon on the catalyst surface and the adsorbed CO2 and H2O. The temperature of the regeneration bed then drops to restore the catalyst activity.

7. The VOCs adsorption, concentration, and catalytic oxidation device according to claim 5, characterized in that, The Fe1Mn2 / Al2O3 low-temperature catalyst was prepared by impregnation using 40-60 mesh porous alumina as a support. The preparation steps are as follows: (1) Weigh ferric nitrate nonahydrate and manganese acetate tetrahydrate according to the Fe to Mn molar ratio of 1:2, and dissolve them together in deionized water to prepare a mixed metal salt solution; (2) Immerse the porous alumina in the mixed metal salt solution for 12-24 hours; (3) Dry the impregnated porous alumina carrier in an oven at 100℃±5℃ for 10-12 hours; (4) The dried porous alumina loaded with iron and manganese bimetallic metals was calcined in a muffle furnace at 500℃±5℃ for 3-5 hours to obtain the primary product of the catalyst. (5) The primary product of the catalyst is compressed and molded in a molding die to prepare the honeycomb-shaped final product of the Fe1Mn2 / Al2O3 low-temperature catalyst.

8. The VOCs adsorption, concentration, and catalytic oxidation device according to claim 5, characterized in that, The hydrophobic hierarchical porous zeolite molecular sieve adsorbent is a silanized modified NaY type honeycomb zeolite molecular sieve with a temperature resistance ≥550℃, a moisture absorption rate <3%, a static VOCs adsorption capacity ≥220mg / g, and an adsorption capacity decay rate ≤10% in the relative humidity range of 0~90%RH. The areas of the first sector, the second sector, and the third sector account for 70%, 15%, and 15% of the rotating moving bed, respectively.

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