Simultaneous removal of no and vocs at medium-low temperature x Cryptomelane-based core-shell catalyst for simultaneous removal of no and vocs, and preparation method and application thereof

Abstract

The application discloses a kind of low-temperature synergic removal NO x And VOCs of cryptomelane-based core-shell catalyst and its preparation method and application.The catalyst is with cryptomelane supported copper oxide (Cu-OMS-2) as core, TiO2 as shell, and forms Cu-OMS-2@TiO2 core-shell composite structure, wherein TiO2 accounts for 20%~35%, CuO doping amount is 5%~20%, and the balance is cryptomelane (OMS-2).By using space limit under the condition of 175~300 ℃, the active sites are separated by coupling interface electron limit, the efficient synergic removal of NO x And VOCs is realized, and the efficiency is greater than 90%, which significantly relieves the mutual inhibition between the two types of reactions, reduces the generation of secondary pollutants, and has excellent stability.The catalyst is suitable for low-temperature industrial flue gas purification and has good industrial application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of environmental catalysis technology, and in particular to a kind of low-temperature synergistic removal of NO x And VOCs of cryptomelane-based core-shell catalyst and its preparation method and application. BACKGROUND

[0002] Nitrogen oxides (NO x ) emissions account for a significant proportion of total industrial emissions. In the steel production process, the main pollutants generated in the coking process include NO x and volatile organic compounds (VOCs). Achieving synergistic and efficient removal of NO x and VOCs has become a key technical problem that the industry needs to solve. NO x and VOCs not only directly harm human health, but also undergo photochemical reactions under light conditions to generate ozone and secondary fine particulate matter (PM 2.5 ), exacerbating haze and ozone pollution and causing respiratory and cardiovascular diseases. Toluene and other VOC components are toxic and carcinogenic, posing a serious threat to the environment and public safety.

[0003] Currently, ammonia selective catalytic reduction (NH3-SCR) is the most widely used denitration technology in industry, and the mainstream commercial catalyst is V2O5-WO3 / MoO3 / TiO2 catalyst. However, this type of catalyst has poor catalytic reduction activity for NO at low temperatures (180-320℃), and does not show significant removal effect for VOCs. However, coke oven flue gas has low exhaust gas temperature, complex composition, and large fluctuations in pollutant concentration, making it difficult for traditional vanadium-based catalysts to meet the current requirements for synergistic control of multiple pollutants.

[0004] Manganese-based catalysts, particularly manganese dioxide (MnO2), have shown good potential in low-temperature NH3-SCR and VOCs catalytic oxidation due to their multi-valence (Mn 2+ / Mn 3+ / Mn 4+ ) characteristics and excellent low-temperature redox ability. Among them, natural cryptomelane (OMS-2) has a unique 2×2 tunnel structure, which is beneficial to the adsorption and activation of NH3 molecules, and exhibits excellent low-temperature denitration performance. However, natural OMS-2 still has problems such as low specific surface area and insufficient exposure of active sites, which limits its catalytic performance and stability under real complex flue gas conditions. In addition, manganese-based catalysts often have low nitrogen selectivity and high N2O byproduct generation in SCR reactions, which can easily cause secondary pollution.

[0005] To improve the catalytic performance of natural OMS-2, researchers have explored various modification methods. Acid treatment (such as washing with glacial acetic acid) enhances the redox capacity of the catalyst by creating abundant defect structures and increasing the specific surface area on the catalyst surface, thereby increasing lattice oxygen activity and reducing the contact restriction between reactants and active sites. On the other hand, introducing copper species to form a Cu-O-Mn interface structure creates a highly efficient electron transport channel. Redox cycles enhance lattice oxygen mobility, accelerate oxygen vacancy generation, and improve low-temperature SCR activity. However, while single-doping modification (such as Cu modification) improves performance to some extent, it fails to fundamentally solve the problem of competitive adsorption and reaction inhibition between NH3 and VOCs (such as toluene) molecules at the same active sites, making it difficult to achieve truly efficient synergistic removal.

[0006] In summary, the development of a method for efficient and synergistic NO removal at medium and low temperatures is crucial. x Catalysts that can neutralize VOCs and possess high N2 selectivity and low secondary pollution characteristics have become an urgent need in the field of flue gas purification. Overcoming competition for active sites and interference with reaction pathways through material structure design is crucial for achieving NO reduction. x The key lies in the synergistic degradation with VOCs. Summary of the Invention

[0007] To address the limitations of existing manganese-based catalysts in the synergistic removal of NO x To address the technical problems encountered in the removal of NO from VOCs, such as insufficient low-temperature activity, low N2 selectivity, easy generation of secondary N2O pollution, and competitive adsorption of NH3 and VOCs molecules at active sites leading to mutual inhibition of the reaction, this invention provides a medium-to-low temperature synergistic removal method for NO. x A cryptomanganese potassium ore-based core-shell catalyst for NO and VOCs, its preparation method, and its application. This catalyst can achieve NO reduction in a low-temperature range of 175–300℃. x It can efficiently reduce VOCs while efficiently oxidizing them, and has good structural stability and nitrogen selectivity.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A medium-low temperature synergistic NO removal method x The cryptomonas-based core-shell catalyst for VOCs is a Cu-OMS-2@TiO2 core-shell structure with CuO-modified cryptomonas-2 as the core and ordered mesoporous TiO2 as the shell. The ordered mesoporous TiO2 shell layer is confined and coated on the surface of the Cu-OMS-2 core layer by a general kinetic control coating method.

[0010] Furthermore, based on the total mass of the catalyst being 100%, the composition of the cryptomanganese potassium ore-based core-shell catalyst is as follows:

[0011] TiO2: 20%~35% (more preferably 25%~30%), CuO: 5%~20% (more preferably 10%~15%), balance being cryptomonzoic acid ore OMS-2.

[0012] Furthermore, the ordered mesoporous TiO2 shell provides spatial confinement, interfacial electronic confinement, and lattice confinement effects for the Cu-OMS-2 core layer. The cryptomanganese potassium ore-based core-shell catalyst possesses a rich pore structure, with a specific surface area, total pore volume, and average pore size of 100-150 μm. 2 / g, 0.2-0.3cm 3 / g, 5-20nm.

[0013] The preparation method of the above-mentioned cryptomanganese potassium ore-based core-shell catalyst includes the following steps:

[0014] S1. Natural cryptomonazine ore is pretreated by water washing and acid washing to obtain acid-washed OMS-2 material, denoted as HAc-OMS-2.

[0015] S2. Using a deposition precipitation method, CuO is loaded onto the HAc-OMS-2 obtained in step S1 to obtain Cu-OMS-2 core layer material;

[0016] S3. Using a general kinetic controlled coating method, with tetrabutyl titanate as the titanium source, the Cu-OMS-2 core layer material obtained in step S2 is used to coat the TiO2 shell to obtain the precursor.

[0017] S4. The precursor obtained in step S3 is calcined to obtain the cryptomanganese potassium mineral-based core-shell catalyst Cu-OMS-2@TiO2.

[0018] Furthermore, in step S1, the acid used for pickling is a 0.75~1.25mol / L glacial acetic acid solution, the treatment temperature is 60±1℃, and the treatment time is 2~4h.

[0019] Furthermore, in step S2, the copper source is copper nitrate trihydrate, the precipitant is a 0.3~0.6 mol / L Na2CO3 solution, the pH of the reaction system is adjusted to 9~10, and the aging time is 40~80 min.

[0020] Further, in step S3, the general kinetic controlled coating method involves adding tetrabutyl titanate at a rate of 0.15~0.5 mL / min to a mixed system containing Cu-OMS-2, anhydrous ethanol and ammonia under a constant temperature of 45±1℃, and reacting for 12~36 hours, wherein the volume of ammonia accounts for 0.2%~0.4% of the mixed system.

[0021] Furthermore, in step S4, the calcination conditions are as follows: under an air atmosphere, the temperature is increased to 350-450°C at a rate of 1-5°C / min, and held for 3-6 hours.

[0022] The preparation principle of the aforementioned general kinetic-controlled coating method is as follows: During the construction of core-shell nanoparticles, a modified Stöber method is used to precisely control the dropping rate of the titanium source solution under a constant-temperature magnetic stirring environment. This method regulates the growth process of the mesoporous TiO2 shell, thereby achieving the controllable construction of the TiO2 shell in the core-shell structure. This method can control the hydrolysis and condensation rates by adjusting the ratio of ammonia to anhydrous ethanol (0.2~0.4 vol%), effectively controlling the growth rate and thickness of the shell, ensuring the order and integrity of the mesoporous structure, and providing a reliable process path for the structural regulation of core-shell nanoparticles.

[0023] The above-mentioned cryptomanganese potassium ore-based core-shell catalyst is used for the synergistic removal of nitrogen oxides (NOx) from flue gas at medium and low temperatures. x And volatile organic compounds (VOCs).

[0024] Furthermore, the atmospheric conditions for the flue gas are as follows: NO concentration 400~600 ppm, NH3 concentration 400~600 ppm, VOCs concentration 50~200 ppm, O2 volume fraction 8~12%, reaction temperature 175~300℃, and gas hourly space velocity 20000~60000 h⁻¹. -1 .

[0025] The ordered mesoporous TiO2-confined CuO / cryptomanganese potassium ore core-shell catalyst Cu-OMS-2@TiO2 of this invention can be used for the catalytic purification of NO and VOCs in low-temperature flue gas from stationary or mobile sources. This catalyst, through a precisely designed preparation process (including deionized water washing for impurity removal, glacial acetic acid washing modification, CuO doping via deposition precipitation, and TiO2 confinement coating using a general kinetic control method), achieves a unique triple confinement effect (spatial confinement, interface confinement, and lattice confinement) and optimized surface chemistry. During calcination, the confinement coating effect of TiO2 promotes the dispersion of CuO species and effectively inhibits CuO species aggregation, thereby maintaining activity. Its special core-shell structure and confinement effect bring more active oxygen and acidic sites, improving redox performance and facilitating synergistic catalytic reactions of multiple pollutants, thus showing broad application prospects and economic value in the field of flue gas purification.

[0026] Compared with the prior art, the advantages and effects of the present invention are as follows:

[0027] (1) The catalyst preparation process of this invention is simple, and can be completed by a series of simple and controllable treatment steps such as water washing, acid modification, loading and calcination. It does not require complex equipment or template agents, thus avoiding purity and pollution problems caused by template agent residues. The process is easy to scale up and standardize. The selected raw materials are inexpensive, readily available and environmentally friendly, and have the advantages of being both green and low-cost. Moreover, they do not contain toxic substances such as vanadium, which is more in line with the concept of green chemistry.

[0028] (2) By optimizing process parameters, the present invention can achieve a high yield in the laboratory, and the process is stable and easy to scale up, with good potential for industrial mass production, overcoming the problem that most core-shell catalysts have low yields due to complex preparation.

[0029] (3) The catalyst of this invention has a unique “heterogeneous dual-effect” synergistic mechanism: NO and NH3 can diffuse through the TiO2 shell pores to the core Mn site to undergo SCR reaction and realize the denitrification process; while VOCs (such as toluene) are spatially confined and are mainly catalytically oxidized at the Cu site of the shell and core-shell interface. This mechanism realizes the spatial separation of reaction sites, effectively avoids competitive adsorption, and significantly improves the synergistic removal efficiency.

[0030] (4) The catalyst of this invention has excellent NO content. x Reduction and VOCs oxidation performance. NO removal efficiency is above 70% within 100–350℃, and can reach over 90% within 125–300℃; the ignition temperature of toluene is as low as 175℃, with a conversion rate exceeding 90%. Simultaneous and efficient removal of NO and VOCs (efficiency > 90%) can be achieved within the 175–300℃ range, suitable for multi-pollutant control in medium- and low-temperature flue gas. Attached Figure Description

[0031] Figure 1 The NO2-based synergistic removal methods for low-temperature flue gas prepared in Examples 1 and 1 and 2 are described. x NO removal rate test graph of catalysts containing VOCs under the conditions of Example 2;

[0032] Figure 2 The NO2-based products prepared for the synergistic removal of NO2 from medium- and low-temperature flue gas in Examples 1 and 1 and 2 are as follows. x The toluene conversion test graph of the catalyst containing VOCs under the conditions of Example 2;

[0033] Figure 3 The NO2-based products prepared for the synergistic removal of NO2 from medium- and low-temperature flue gas in Examples 1 and 1 and 2 are as follows. x Nitrogen selectivity curve for catalysts containing VOCs under the conditions of Example 2;

[0034] Figure 4 The NO2-based products prepared for the synergistic removal of NO2 from medium- and low-temperature flue gas in Examples 1 and 1 and 2 are as follows.x Carbon dioxide selectivity curve of catalysts containing VOCs under the conditions of Example 2;

[0035] Figure 5 This is a scanning electron microscope (SEM) image of the OMS-2 catalyst prepared in Comparative Example 1 compared to Example 3;

[0036] Figure 6 Example 3 is a scanning electron microscope image of the Cu-OMS-2@TiO2 core-shell catalyst prepared in Example 1;

[0037] Figure 7 Example 3 shows the adsorption-desorption curves of the Cu-OMS-2@TiO2 core-shell catalyst prepared in Example 1;

[0038] Figure 8 Example 3 shows the pore size distribution of the Cu-OMS-2@TiO2 core-shell catalyst prepared in Example 1;

[0039] Figure 9 The image shown is the XRD pattern of the Cu-OMS-2@TiO2 core-shell catalyst prepared in Example 1, as shown in Example 4. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited thereto.

[0041] Example 1

[0042] The preparation method of the core-shell catalyst Cu-OMS-2@TiO2 is as follows:

[0043] (1) Weigh 6g of natural cryptomonium ore and place it in a 250mL beaker. Add 100mL of deionized water. Stir magnetically for 30min at room temperature (25℃), then let stand for 30min and discard the supernatant. Repeat the above stirring-standing-discarding operation twice, and then perform vacuum filtration. Wash the solid sample with deionized water during the vacuum filtration process. After vacuum filtration, transfer the filter paper with the sample to a clean beaker and place the beaker in a forced-air drying oven. Dry at 60℃ for 12h. Grind the dried sample to 60-100 mesh. This is the natural cryptomonium ore sample washed with deionized water, denoted as OMS-2.

[0044] (2) To prepare a 1 mol / L glacial acetic acid solution, take 90 mL of deionized water and pour it into a volumetric flask; use a pipette to take 5.75 mL of glacial acetic acid solution and transfer it to the volumetric flask; continue to add deionized water to the volumetric flask and make up to the 100 mL mark. Shake well to obtain a 1 mol / L glacial acetic acid solution.

[0045] (3) Glacial acetic acid modification treatment: Add 2g of 60-100 mesh OMS-2 prepared in step (1) to a 250mL beaker, and then pour in 100mL of 1mol / L glacial acetic acid solution prepared in step (2); place the beaker in a 60℃ water bath and stir magnetically for 3h; after stirring, let stand for 30min, and then perform vacuum filtration. During the vacuum filtration process, wash the solid sample with deionized water until the filtrate is neutral; after vacuum filtration, transfer the filter paper with the sample to a clean beaker, place it in a forced-air drying oven, and dry it at 60℃ for 12h. The dried sample is then ground to 60-100 mesh and recorded as HAc-OMS-2.

[0046] (4) To prepare 50 mL of 0.5 mol / L Na2CO3 solution, weigh 2.65 g of Na2CO3 solid, place it in a 100 mL beaker, add 30 mL of deionized water, and sonicate at 25 °C for 3 min to completely dissolve the Na2CO3. Transfer the solution to a 50 mL volumetric flask, wash the beaker 2-3 times with deionized water, and transfer the washing solution into the volumetric flask. Continue to add deionized water to the volumetric flask to the mark, stopper the flask, invert it and shake well to obtain 50 mL of 0.5 mol / L Na2CO3 solution for later use.

[0047] (5) Weigh 0.911 g of copper nitrate trihydrate, place it in a 250 mL beaker, add 90 mL of deionized water, and sonicate at 25 °C for 3 min until completely dissolved. Add 1.1 g of 60-100 mesh HAc-OMS-2 obtained in step (3) to the above solution, and continue sonicating at 25 °C for 5 min; then transfer the beaker to a water bath and stir magnetically at 25 °C. Take 10±1mL of the 0.5mol / L Na2CO3 solution prepared in step (4) and slowly drop it into the beaker. Adjust the pH of the system to 9~10 by pH meter. After the addition is completed, continue stirring for 20min. Stop stirring after a total of 30min. Then let the beaker stand at room temperature (25℃) for 1h to complete the aging. After the aging is completed, collect the solid sample by vacuum filtration. Wash with deionized water to remove impurities during the vacuum filtration. After the vacuum filtration is completed, transfer the filter paper with the sample attached to it to a clean beaker and place it in a forced-air drying oven. Dry it at 60℃ for 12h. Grind the dried sample to 60-100 mesh and record it as Cu-OMS-2.

[0048] (6) Preparation of solution A: Weigh 0.411g of 60-100 mesh Cu-OMS-2 obtained in step (5) and add it to a 250mL beaker containing 100mL of anhydrous ethanol and 0.3mL of ammonia solution with a mass fraction of 25~28%. Sonicate at 25℃ for 15min to obtain a mixed system, which is denoted as solution A.

[0049] (7) Titanium source loading: Transfer the beaker containing solution A to a 45℃ water bath for magnetic stirring; take 0.75 mL of tetrabutyl titanate solution and slowly inject it into solution A within 5 min; keep the magnetic stirring in the 45℃ water bath for 24 h and then centrifuge at 8000 rpm for 8 min; collect the solid sample after centrifugation and put it in a forced-air drying oven to dry at 60℃ for 12 h. The dried sample is named Cu-OMS-2@TiO2.

[0050] (8) The Cu-OMS-2@TiO2 obtained in step (7) is transferred to a crucible and placed in a muffle furnace for calcination. The temperature is increased to 400°C at a heating rate of 2°C / min under air atmosphere and held for 4h. After annealing and cooling for 400min, the powder sample is taken out and sieved. The sample with a mesh size of 60~100 mesh is selected as the core-shell catalyst Cu-OMS-2@TiO2, which is denoted as 15Cu-OMS-2@30TiO2, where 15 indicates that CuO accounts for 15% of the total mass of the catalyst and 30 indicates that TiO2 accounts for 30% of the total mass of the catalyst.

[0051] Comparative Example 1

[0052] The specific preparation steps for the catalyst OMS-2 in Comparative Example 1 are as follows:

[0053] Weigh 2g of natural cryptomanganese potassium ore that has not been washed with deionized water, transfer it to a crucible and place it in a muffle furnace for calcination. Under air atmosphere, heat the ore to 400℃ at a heating rate of 2℃ / min and hold for 4h. After annealing and cooling for 400min, remove the ore and sieve the powder sample. Select the sample with a mesh size of 60~100 as the OMS-2 catalyst.

[0054] Comparative Example 2

[0055] The specific preparation steps for the non-core-shell catalyst Cu-OMS-2 / TiO2 in Comparative Example 2 are as follows:

[0056] Weigh 1.4g of the Cu-OMS-2 sample prepared in step (5) of Example 1 and 0.6g of nano TiO2 powder (anatase, hydrophilic, 99.8%), add it to a 100mL beaker containing 50mL of deionized water, and ultrasonically disperse it at 25℃ for 10min. Then transfer the beaker to a magnetically stirred water bath, stir it at room temperature for 1 hour, then raise the water bath temperature to 80℃ and continue stirring until the deionized water is completely evaporated. Transfer the evaporated beaker to a 60℃ oven to dry for 12h. After drying, transfer the sample to a crucible and place it in a muffle furnace for calcination. In an air atmosphere, raise the temperature to 400℃ at a heating rate of 2℃ / min and hold for 4h. After annealing and cooling for 400min, take it out, sieve the powder sample, and select the 60~100 mesh sample as the Cu-OMS-2 / TiO2 non-core-shell catalyst.

[0057] Activity tests of the catalysts described in Example 1, Comparative Example 1, and Comparative Example 2 for synergistic removal of NO and toluene

[0058] 2.12 mL of catalyst was loaded into a quartz tube fixed-bed reactor with an inner diameter of 6 mm. The total gas flow rate was 400 mL / min and the volume hourly space velocity was 40,000 h⁻¹. -1 The reaction test temperature range was 100~350℃, and the simulated atmosphere composition was: 500ppm NO, 500ppm NH3, 50ppm toluene, 10 vol% O2, and the remainder N2. The performance of the catalyst in catalytically reducing NO and simultaneously catalytically oxidizing toluene under flue gas conditions with coexisting NO and toluene was tested. The test results are as follows: Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the results indicate that the 15Cu-OMS-2@30TiO2 core-shell catalyst prepared in Example 1 exhibits excellent performance in the synergistic degradation of NO and toluene under medium and low temperature conditions, and there is a significant mutual promoting effect between the selective catalytic reduction reaction of NH3 and the oxidation reaction of toluene.

[0059] SEM and BET tests of the catalyst of this invention

[0060] This invention utilizes a Thermo Fisher Scientific Apreo 2S field emission scanning electron microscope to observe the morphology and surface structure of the catalyst. N2 physical adsorption-desorption experiments were performed using a 3Flex America Micromeritics instrument to characterize the specific surface area and pore size distribution of the catalyst. After pretreatment of a 0.1 g sample, N2 was used as the adsorbent at 77 K. Appropriate specific surface area, total pore volume, and average pore size were obtained according to the Brunauer-Joyner-Halenda (BET) and Density Functional Theory (DFT) methods.

[0061] Taking the test results of the samples obtained in Example 1 and Comparative Example 1 as examples, the test results are as follows: Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown in the figure, the results indicate that the OMS-2 prepared in Comparative Example 1 exhibits a typical nanorod structure with a rough surface and a specific surface area of ​​30.42 m². 2 / g, pore volume is 0.22cm³ 3 / g, with an average pore size of 29.09 nm, the 15Cu-OMS-2@30TiO2 prepared in Example 1 maintained the nucleus morphology of OMS-2, with no obvious CuO species agglomeration. The outer layer was covered by a uniform, dense, and porous TiO2 shell, with a specific surface area of ​​104.40 m² / g. 2 / g, pore volume is 0.22cm³ 3 It has an average pore size of 8.43 nm and a rich micro-mesoporous structure and a large specific surface area.

[0062] XRD testing of the catalyst of this invention

[0063] The phase structure of the catalyst in this invention was analyzed and characterized using a Bruker-D8 ADVANCE X-ray diffractometer (Germany). The test conditions were: Cu target Kα rays (λ=1.5406Å), scanning 2θ range of 10°~80°, and scanning speed of 5° / min. The test results are as follows: Figure 9 As shown, OMS-2 (cryptomanganese potassium α-MnO2) exhibits characteristic diffraction peaks at 2θ values ​​of approximately 12.8°, 18.1°, 28.8°, 37.5°, 49.9°, 56.9°, 60.3°, and 69.7°, corresponding to the (110), (200), (310), (211), (411), (600), (521), and (541) crystal planes, respectively, which are similar to the standard tetragonal KMn8O 16 The structure (JCPDS No. 29-1020) is highly consistent. The anatase TiO2 phase exhibits significant peaks at 25.3°, 37.8°, 48.0°, 53.9°, 55.1°, 62.7°, and 75.0°, which are indexed to the (101), (004), (200), (105), (204), and (215) crystal planes, respectively, consistent with the anatase TiO2 reference standard (JCPDS No. 21-1272). The diffraction peaks of the 15Cu-OMS-2@30TiO2 catalyst mainly correspond to the α-MnO2 and anatase TiO2 phases, with a small contribution from CuMn2O4. This indicates that Cu was successfully incorporated into the OMS-2 framework, and that TiO2 was uniformly dispersed without significant phase separation. The (211) diffraction peak of 15Cu-OMS-2@30TiO2 shows a significant low-angle shift relative to OMS-2. This shift indicates an increase in the interlayer spacing within the (211) plane, confirming lattice expansion due to Cu incorporation. This is attributed to the larger ionic radius of Cu ions relative to Mn, leading to distortion of the OMS-2 tunnel structure. This lattice distortion achieves a lattice confinement effect, which, through the Cu-O-Mn interface modulation, promotes the generation of oxygen vacancies and electron transfer, thereby enhancing the redox performance and stability of the catalyst.

Claims

1. A method for synergistic NO removal at medium and low temperatures x A cryptomanganese potassium mineral-based core-shell catalyst for VOCs, characterized in that, The cryptomonopotassium ore-based core-shell catalyst is a Cu-OMS-2@TiO2 core-shell structure with CuO modified cryptomonopotassium ore as the core and ordered mesoporous TiO2 as the shell. The ordered mesoporous TiO2 shell layer is confined and coated on the surface of the Cu-OMS-2 core layer by a general kinetic control coating method.

2. The low-temperature synergistic NO removal method according to claim 1 x A cryptomanganese potassium mineral-based core-shell catalyst for VOCs, characterized in that, Based on the total mass of the catalyst (100%), the composition of the cryptomanganese potassium ore-based core-shell catalyst is as follows: TiO2: 20%~35%, CuO: 5%~20%, balance is cryptomonzoic acid ore OMS-2.

3. The low-temperature synergistic NO removal method according to claim 1 x A cryptomanganese potassium mineral-based core-shell catalyst for VOCs, characterized in that, The ordered mesoporous TiO2 shell provides spatial confinement, interfacial electronic confinement, and lattice confinement effects for the Cu-OMS-2 core layer. The surface area, total pore volume, and average pore size of the cryptomanganese potassium mineral-based core-shell catalyst are 100-150 μm. 2 / g, 0.2-0.3cm 3 / g, 5-20nm.

4. The method for preparing the cryptomanganese potassium ore-based core-shell catalyst according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Natural cryptomonazine ore is pretreated by water washing and acid washing to obtain acid-washed OMS-2 material, denoted as HAc-OMS-2. S2. Using a deposition precipitation method, CuO is loaded onto the HAc-OMS-2 obtained in step S1 to obtain Cu-OMS-2 core layer material; S3. Using a general kinetic controlled coating method, with tetrabutyl titanate as the titanium source, the Cu-OMS-2 core layer material obtained in step S2 is used to coat the TiO2 shell to obtain the precursor. S4. The precursor obtained in step S3 is calcined to obtain the cryptomanganese potassium mineral-based core-shell catalyst Cu-OMS-2@TiO2.

5. The method for preparing the cryptomanganese potassium ore-based core-shell catalyst according to claim 4, characterized in that, In step S1, the acid used for pickling is a 0.75~1.25mol / L glacial acetic acid solution, the treatment temperature is 60±1℃, and the treatment time is 2~4h.

6. The method for preparing the cryptomanganese potassium ore-based core-shell catalyst according to claim 4, characterized in that, In step S2, the copper source is copper nitrate trihydrate, the precipitant is a 0.3~0.6 mol / L Na2CO3 solution, the pH of the reaction system is adjusted to 9~10, and the aging time is 40~80 min.

7. The method for preparing the cryptomanganese potassium ore-based core-shell catalyst according to claim 4, characterized in that, In step S3, the general kinetic control coating method involves adding tetrabutyl titanate at a rate of 0.15 to 0.5 mL / min to a mixed system containing Cu-OMS-2, anhydrous ethanol, and ammonia under a constant temperature of 45±1℃, and reacting for 12 to 36 hours, wherein the volume of ammonia accounts for 0.2% to 0.4% of the mixed system.

8. The method for preparing the cryptomanganese potassium ore-based core-shell catalyst according to claim 4, characterized in that, In step S4, the calcination conditions are as follows: under an air atmosphere, the temperature is increased to 350-450℃ at a rate of 1-5℃ / min, and held for 3-6 hours.

9. The application of the cryptomanganese potassium ore-based core-shell catalyst according to any one of claims 1 to 3 or the cryptomanganese potassium ore-based core-shell catalyst obtained by the preparation method according to any one of claims 4 to 8, characterized in that, The cryptomanganese potassium ore-based core-shell catalyst is used for the synergistic removal of nitrogen oxides (NOx) from flue gas at medium and low temperatures. x And volatile organic compounds (VOCs).

10. The application according to claim 9, characterized in that, The atmospheric conditions for the flue gas were: NO concentration 400-600 ppm, NH3 concentration 400-600 ppm, VOCs concentration 50-200 ppm, O2 volume fraction 8-12%, reaction temperature 175-300℃, and gas hourly space velocity 20000-60000 h⁻¹. -1 .

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