Copper-based carbon zeolite composite substrate catalyst for complex vocs catalytic oxidation and preparation method thereof

Abstract

The application provides a copper-based carbon zeolite composite substrate catalyst for catalytic oxidation of complex VOCs and a preparation method thereof. A zeolite molecular sieve is ion exchanged by being added into a solution containing a metal coordination ion salt, then mixed with an organic ligand solution, and subjected to hydrothermal reaction at 80-160 DEG C. The obtained composite intermediate is carbonized at 350-800 DEG C in an inert atmosphere, a reducing atmosphere or a weak oxidizing atmosphere. In the carbonization process, the metal organic framework in the composite intermediate is converted into a porous carbon containing nano active metal oxide, and the porous carbon and the zeolite molecular sieve form a carbon-zeolite substrate with a hierarchical pore structure, the nano active metal oxide is uniformly dispersed and anchored on the carbon-zeolite substrate. The application forms new porous structures and adsorption centers, a multi-level pore structure and a heterogeneous chemical surface while forming the nano active metal oxide, and effectively improves the catalytic activity, stability and ability to adapt to complex working conditions of the catalyst.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials and relates to a copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs and its preparation method. Background Technology

[0002] Volatile organic compounds (VOCs) are important precursors to the formation of fine particulate matter (PM2.5) and ozone (O3), making the development of efficient VOCs removal technologies crucial for environmental remediation. Among existing VOCs purification technologies, catalytic oxidation has been widely used due to its advantages such as simple operation, low energy consumption, high treatment efficiency, and minimal secondary pollution. However, realizing the advantages of catalytic oxidation technology hinges on the development of low-temperature catalysts with high activity, high stability, and excellent water resistance.

[0003] Supported catalysts are a widely used type of catalyst, characterized by high dispersion of the active phase and excellent thermal stability of the metal and its oxides. Carbon / zeolite composites are novel materials based on porous carbon and zeolite molecular sieves, capable of forming hierarchical porous structures, more adsorption centers, and heterogeneous chemical surfaces, making them one of the ideal supports for preparing highly efficient VOCs oxidation catalysts. Currently, the main method for preparing carbon / zeolite composites involves adding biochar to a hot alkaline solution. To achieve catalytic functionalization, metals are often loaded through post-treatment methods such as physical mixing, impregnation, and vapor deposition. However, this approach suffers from problems such as large size of the active component, uneven distribution, and low loading, which are detrimental to improving catalytic reaction performance.

[0004] Metal-organic frameworks (MOFs) are crystalline porous materials with a periodic network structure formed by the self-assembly of metal ions and organic ligands. They possess high specific surface area, tunable porosity, and regular pore structure. After heat treatment, the metal clusters in MOFs transform into metal nanoparticles or metal oxide nanoparticles, and the organic framework transforms into porous carbon materials, resulting in materials where metal particles are coated with porous carbon. However, materials obtained by direct pyrolysis of MOFs have relatively low metal loading, and in actual high-temperature thermocatalysis processes, the organic framework cannot maintain a stable crystal structure, which reduces the activity and stability of the catalyst in application.

[0005] CN 106064087 A discloses a method for preparing a VOCs catalytic combustion catalyst, the operation of which is as follows: preparing a solution A containing at least one metal compound, preparing a solution B containing an organic ligand, adding solution B to solution A, and stirring to obtain a mixed solution; placing a support in the mixed solution and impregnating it at a constant temperature to obtain a MOF / support material; preparing a solution C containing at least one metal compound, placing the MOF / support material in solution C for loading; aging the obtained material, drying it, and then calcining it in an air atmosphere at 500-800℃ to convert the metal ions in the material into active oxide species loaded on the support material. Although the catalyst prepared by this method has a high metal loading due to the secondary loading of metal compounds in the ordered cavity of MOF, and the derived metal active centers are highly dispersed due to the unique network structure of MOF, the calcination process in the air atmosphere only forms active oxide species and loads them onto the support. It merely utilizes MOFs to provide metal oxide active centers and active center loading sites, without generating a synergistic effect between MOFs and the support material to further improve the catalyst performance. The utilization rate of the excellent potential of MOFs is low. Summary of the Invention

[0006] Existing methods for preparing catalysts for the catalytic oxidation of VOCs only utilize the active centers of metal oxides provided by MOF materials or as loading sites, resulting in low utilization of the excellent potential of MOF materials and insufficient improvement in the catalytic oxidation activity of the prepared catalysts for VOCs. Furthermore, addressing the current need for treating complex VOCs, this invention provides a copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs and its preparation method, thereby improving the catalyst's activity in catalytic oxidation of VOCs and endowing the catalyst with good stability and water resistance, achieving efficient catalytic oxidation removal of complex VOCs.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs includes the following steps:

[0009] (1) Dissolve the metal coordination ion salt in a mixed solvent of water and organic solvent to obtain solution A. The metal coordination ion salt includes at least a first coordination metal ion salt, which is a water-soluble copper salt. Disperse the zeolite molecular sieve fully in solution A and let it stand to allow for sufficient ion exchange to obtain dispersion A. In dispersion A, the mass ratio of zeolite molecular sieve to metal coordination ion salt is (0.1~1):1.

[0010] The organic ligand 1,3,5-benzenetricarboxylic acid was dissolved in a mixed solvent of water and organic solvent to obtain solution B;

[0011] (2) Add solution B to dispersion A, mix thoroughly, and control the ratio of dispersion A to solution B so that Cu 2+ The molar ratio with 1,3,5-benzenetricarboxylic acid is (0.2–3):1;

[0012] (3) Transfer the mixture obtained in step (2) to the reaction vessel and carry out a full hydrothermal reaction at 80-160℃. During the hydrothermal reaction, the organic ligand coordinates with the free metal coordination ions and the metal particles on the zeolite molecular sieve, and self-assembles in situ on the zeolite molecular sieve to form a metal-organic framework covering the zeolite molecular sieve. Centrifuge the obtained reaction solution, collect the solid product, wash and dry the solid product to obtain the composite intermediate.

[0013] (4) The composite intermediate obtained in step (3) is subjected to full carbonization at 350-800°C in an inert atmosphere, a reducing atmosphere or a weak oxidizing atmosphere with an oxygen content of less than 1.0 vol.%. During the carbonization process, the metal-organic framework in the composite intermediate is transformed into porous carbon containing nano-active metal oxides, and the porous carbon and zeolite molecular sieve form a carbon-zeolite substrate with a hierarchical pore structure. The nano-active metal oxides are uniformly dispersed and anchored on the carbon-zeolite substrate, thus obtaining the copper-based carbon-zeolite composite substrate catalyst.

[0014] In the above technical solution, the cation of the zeolite molecular sieve is Na. + Furthermore, the zeolite molecular sieve is a Y-type zeolite molecular sieve, an X-type zeolite molecular sieve, or a ZSM-type zeolite molecular sieve.

[0015] In the above technical solution, the organic solvent in step (1) is ethanol, or ethanol and N,N-dimethylformamide. Further, when the organic solvent in step (1) is ethanol, the volume ratio of water to ethanol in the mixed solvent of water and organic solvent is preferably 1:(0.8~1.2); when the organic solvent in step (1) is ethanol and N,N-dimethylformamide, the volume ratio of water, ethanol and N,N-dimethylformamide is preferably 1:(0.8~1.2):(0.8~1.2).

[0016] In step (2) of the above technical solution, solution B is added to dispersion A and thoroughly stirred and mixed. The ratio of dispersion A to solution B is controlled so that Cu 2+ The concentration is 0.1–0.3 mol / L.

[0017] In step (3) of the above technical solution, it is preferable to carry out the hydrothermal reaction under stirring conditions. For example, during the hydrothermal reaction, a homogeneous reaction vessel is used to apply stirring, and the stirring speed can usually be controlled to be 40 to 100 rpm.

[0018] In step (3) of the above technical solution, it is preferable to control the hydrothermal reaction time to be 6 to 36 hours.

[0019] In step (4) of the above technical solution, the carbonization time is preferably controlled to be 1 to 5 hours.

[0020] Furthermore, in step (4) of the above technical solution, the composite intermediate obtained in step (3) is placed in a tube furnace, and an inert atmosphere, a reducing atmosphere, or a weak oxidizing atmosphere with an oxygen content of less than 1.0 vol.% is introduced to remove air from the tube furnace. Then, under the condition of introducing an inert atmosphere, a reducing atmosphere, or a weak oxidizing atmosphere with an oxygen content of less than 1.0 vol.%, the temperature of the tube furnace is raised to 350-800°C at a heating rate of 1-10°C / min, and sufficient carbonization is carried out while maintaining the aforementioned temperature.

[0021] In step (4) of the above technical solution, the inert atmosphere can be a nitrogen atmosphere or an argon atmosphere; the reducing atmosphere can be a hydrogen atmosphere or a carbon monoxide atmosphere; the weak oxidizing atmosphere with an oxygen content of less than 1.0 vol.% is usually a mixture of oxygen and an inert gas, and the oxygen content in the mixture is less than 1.0 vol.%, for example, it can be a mixture of oxygen and nitrogen with an oxygen content of less than 1.0 vol.%.

[0022] In step (4) of the above technical solution, the preferred carbonization temperature is 400-600℃.

[0023] In the above technical solution, the metal coordination ion salt in step (1) further includes a second coordination metal ion salt, which includes at least one of water-soluble manganese salt, water-soluble cobalt salt, and water-soluble iron salt. When the metal coordination ion salt in step (1) simultaneously includes a first coordination metal ion salt and a second coordination metal ion salt, the prepared copper-based carbon zeolite composite substrate catalyst has multiple nano-active metal oxides, that is, the construction of multi-metal active centers is realized in the catalyst.

[0024] In the above technical solution, the pore structure of the carbon-zeolite substrate with hierarchical pore structure formed in step (4) consists of small pores with a pore size of no more than 2 nm, mesopores with a pore size of 5 to 50 nm, and macropores with a pore size of more than 50 nm but less than 200 nm.

[0025] The present invention also provides a copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs prepared by the above technical solution.

[0026] A feasible method for catalytic oxidation of VOCs using the aforementioned copper-based carbon zeolite composite substrate catalyst is as follows: Under normal pressure, the aforementioned copper-based carbon zeolite composite substrate catalyst is loaded into a fixed-bed reactor, and a gas containing VOCs is introduced. The VOCs are then catalytically oxidized under appropriate temperature conditions. Typically, the introduced gas containing VOCs can contain one or more types of VOCs, with a concentration of 100–2000 ppm. The oxygen concentration is controlled at 20 vol%, and nitrogen is used as the balance gas. The gas space velocity (GHSV) is 30,000–120,000 mL·g⁻¹. cat -1 ·h -1 Catalytic oxidation is carried out at a temperature of 250–330℃.

[0027] The principle of this invention is as follows: First, a zeolite molecular sieve, a solution containing a metal coordination ion salt, and an organic ligand solution are subjected to ion exchange, coordination, crystallization, and precipitation processes in a single pot. During this process, the zeolite molecular sieve induces the organic ligand to undergo a coordination reaction with the metal coordination ions therein, resulting in in-situ self-assembly of MOFs on the surface and pore structure walls of the zeolite molecular sieve. The formed MOFs encapsulate the metal ions within the porous structure of the zeolite molecular sieve and coat the zeolite molecular sieve, yielding a composite intermediate. This in-situ self-assembly method ensures that the active ingredients are uniformly distributed in situ, effectively reducing the agglomeration of active components during subsequent calcination, thereby achieving a high loading rate and high dispersion of the active components. Based on this, the composite intermediate is calcined in an inert, reducing, or weakly oxidizing atmosphere to achieve carbonization. During carbonization, the metal-organic framework in the composite intermediate is transformed into porous carbon containing nano-active metal oxides. The porous carbon and zeolite molecular sieves form a carbon-zeolite substrate with a hierarchical pore structure. The nano-active metal oxides are highly dispersed, uniformly dispersed, and anchored on the carbon-zeolite substrate, resulting in the copper-based carbon-zeolite composite substrate catalyst of this invention. The carbon-zeolite substrate formed by the method of this invention not only retains the pore structure and surface characteristics of the zeolite molecular sieve and porous carbon, but also exhibits synergistic and bifunctional effects. New porous structures and adsorption centers, hierarchical pore structures, and heterogeneous chemical surfaces are formed in the catalyst, all of which are beneficial for improving the accessibility of multidirectional active channels and the surface ion exchange and molecular selectivity in multiphase reactions. The hierarchical porous structure of this catalyst effectively enhances the mass transfer rate of reactant molecules during gas-solid catalytic reactions, while simultaneously providing ample reactive sites for surface adsorption and catalytic conversion due to its large specific surface area. The catalyst's carbon-zeolite substrate with its heterogeneous chemical surface and multi-element catalytic active centers improves its adaptability to complex industrial emission conditions. Furthermore, by employing hydrophobic zeolite molecular sieves with a high Si / Al ratio, the catalyst's hydrophilicity / hydrophobicity can be controlled, further enhancing its activity stability and adaptability to complex operating conditions.

[0028] Compared with the prior art, the technical solution provided by the present invention has the following beneficial technical effects:

[0029] 1. This invention provides a method for preparing a copper-based carbon-zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs, mainly comprising two steps: in-situ self-assembly to prepare a composite intermediate and pyrolysis of the composite intermediate. First, using zeolite molecular sieves, a solution containing metal coordination ions, and an organic ligand solution as the main reagents, a one-pot process including ion exchange, coordination, crystallization, and precipitation is carried out, allowing the organic ligands to coordinate with the metal coordination ions in the zeolite molecular sieve, resulting in in-situ self-assembly on the surface and pore walls of the zeolite molecular sieve to form a composite intermediate with MOFs coating the zeolite molecular sieve. Then, the composite intermediate is carbonized in an inert atmosphere, a reducing atmosphere, or a weakly oxidizing atmosphere, transforming the metal-organic framework in the composite intermediate into porous carbon containing nano-active metal oxides. This porous carbon is bonded to the zeolite molecular sieve to form a carbon-zeolite substrate with a hierarchical pore structure, while the nano-active metal oxides are uniformly dispersed and anchored on the carbon-zeolite substrate. Compared with existing methods for preparing catalysts based on MOFs, this invention fully utilizes the excellent potential of MOF materials. While forming nano-active metal oxides, it also forms new porous structures and adsorption centers, hierarchical pore structures, and heterogeneous chemical surfaces, which effectively improves the catalytic activity, stability, and ability to adapt to complex working conditions of the catalyst.

[0030] 2. Due to the excellent stability of zeolite molecular sieves, the catalysts prepared through in-situ self-assembly and pyrolysis carbonization also have excellent stability. At the same time, by selecting hydrophobic zeolite molecular sieves, the catalysts can also be endowed with excellent water resistance, thereby enabling the catalysts to better meet the requirements of complex working conditions in actual scenarios.

[0031] 3. Experiments have confirmed that the catalyst prepared by the method of this invention has excellent catalytic oxidation performance for VOCs, including toluene and acetone, especially in terms of time stability and water resistance.

[0032] 4. The method described in this invention has a simple process, strong controllability, and is conducive to reducing production costs and promoting its application. Attached Figure Description

[0033] Figure 1 Figures (A) and (B) are SEM images of CuC prepared in Example 1 and CuC@NaY prepared in Example 2.

[0034] Figure 2 Figures (A) to (C) are SEM-mapping images of CuC prepared in Comparative Example 1. Figure 2Figures (D) to (I) are SEM-mapping images of CuC@NaY prepared in Example 2.

[0035] Figure 3 Figures (A) and (B) show the nitrogen adsorption-desorption curves and pore size distribution of CuC@NaY, CuC@HZSM-5, and CuC@13X prepared in Examples 2-4.

[0036] Figure 4 The figures show the performance curves of Cu / NaY and CuC@NaY catalytic oxidation of toluene prepared in Comparative Example 2 and Example 2.

[0037] Figure 5 The figures show the performance curves of CuC prepared in Comparative Example 1, CuC@NaY-S prepared in Example 1, and CuC@NaY prepared in Example 2 for catalytic oxidation of toluene.

[0038] Figure 6 The performance curves of CuC@NaY, CuC@HZSM-5, and CuC@13X prepared in Examples 2-4 for catalytic oxidation of toluene and acetone are shown.

[0039] Figure 7 Figure (A) shows the CuC@NaY prepared in Example 5. 3.3：1 Performance curves of catalytic oxidation of complex VOCs Figure 7 Figure (B) shows the CuC@NaY prepared in Example 5. 3.3：1 The results of CO2 selectivity testing for complex VOCs are shown in the figure. T / Tol represents toluene, and A / Ac represents acetone.

[0040] Figure 8 Figures (A) and (B) show the CuC@NaY prepared in Example 5. 3.3：1 Stability and water resistance test results of catalytic oxidation of complex VOCs.

[0041] Figure 9 Figures (A) and (B) show CuC and CuC@NaY prepared in Comparative Example 1 and Example 5, respectively. 3.3：1 Stability and water resistance test results of catalytic oxidation of toluene.

[0042] Figure 10 Figures (A) and (B) show CuC and CuC@NaY prepared in Comparative Example 1 and Example 5, respectively. 3.3：1 Stability and water resistance test results of catalytic oxidation of acetone. Detailed Implementation

[0043] The following examples further illustrate the copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs provided by the present invention and its preparation method. It should be noted that the following examples are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0044] In the following examples and comparative examples, unless specific experimental conditions are specified, they were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, unless the manufacturer is specified, are all conventional products that can be purchased commercially.

[0045] Example 1

[0046] In this embodiment, a copper-based carbon zeolite composite substrate catalyst CuC@NaY-S for the catalytic oxidation of complex VOCs is prepared by the following steps:

[0047] (1) Dissolve Cu(NO3)2·3H2O in a mixture of deionized water, ethanol (EtOH) and N,N-dimethylformamide (DMF) (the volume ratio of deionized water, EtOH and DMF is 1:1:1) to obtain solution A.

[0048] Commercial NaY zeolite molecular sieve was added to solution A and ultrasonically treated for 10 min to ensure that the NaY zeolite molecular sieve was fully dispersed in solution A. Then, it was allowed to stand for 50 min to allow for sufficient ion exchange, resulting in dispersion A. In dispersion A, the mass ratio of NaY zeolite molecular sieve to Cu(NO3)2·3H2O was 0.2:1.

[0049] The organic ligand 1,3,5-benzenetricarboxylic acid (H3BTC) was dissolved in a mixture of deionized water, ethanol and DMF (the volume ratio of water, EtOH and DMF was 1:1:1) to obtain solution B.

[0050] (2) Quickly add solution B to dispersion A and stir at room temperature for 60 min to mix them thoroughly. Control the ratio of dispersion A to solution B so that the concentration of Cu(NO3)2·3H2O in the mixture obtained in this step is 0.1769 mol / L and the concentration of H3BTC is 0.0945 mol / L, that is, the molar ratio of Cu(NO3)2·3H2O to H3BTC is 1.87:1.

[0051] (3) Transfer the mixture obtained in step (2) to the reactor and carry out hydrothermal reaction under static conditions. Control the reaction temperature to 80℃ and the reaction time to 24h. Cool the obtained reaction solution to room temperature naturally, collect the solid product by centrifugation, wash the solid product with DMF and EtOH three times respectively, and then dry it at 80℃ overnight to obtain the composite intermediate CuBTC@NaY-S.

[0052] (4) Place the CuBTC@NaY-S obtained in step (3) into a tube furnace and continuously introduce nitrogen into the tube furnace at a flow rate of 100 mL / min. After completely removing the air from the tube furnace, heat the furnace to 500°C at a heating rate of 5°C / min and maintain the temperature for 2 hours to obtain the catalyst CuC@NaY-S.

[0053] Example 2

[0054] In this embodiment, a copper-based carbon zeolite composite substrate catalyst CuC@NaY was prepared for the catalytic oxidation of complex VOCs.

[0055] The operation of this embodiment is basically the same as that of embodiment 1, except that the homogeneous hydrothermal reaction is carried out at a stirring speed of 40 r / min in step (3).

[0056] Comparative Example 1

[0057] In this comparative example, the preparation of the metal-organic framework-derived copper-based carbon catalyst CuC follows these steps:

[0058] (1) Dissolve Cu(NO3)2·3H2O in a mixture of deionized water, EtOH and DMF (the volume ratio of deionized water, EtOH and DMF is 1:1:1) to obtain solution A.

[0059] H3BTC was dissolved in a mixture of deionized water, ethanol and DMF (the volume ratio of water, EtOH and DMF was 1:1:1) to obtain solution B.

[0060] (2) Quickly add solution B to solution A and stir at room temperature for 60 min to mix them thoroughly. Control the ratio of solution A to solution B so that the concentration of Cu(NO3)2·3H2O in the mixture obtained in this step is 0.1769 mol / L and the concentration of H3BTC is 0.0945 mol / L, that is, the molar ratio of Cu(NO3)2·3H2O to H3BTC is 1.87:1.

[0061] (3) Transfer the mixture obtained in step (2) to the reactor and carry out a homogeneous hydrothermal reaction at a stirring speed of 40 r / min. Control the reaction temperature to 80℃ and the reaction time to 24 h. Cool the obtained reaction solution to room temperature naturally, collect the solid product by centrifugation, wash the solid product with DMF and deionized water three times, and then dry it at 80℃ overnight to obtain the intermediate CuBTC.

[0062] (4) Place the CuBTC obtained in step (3) into a tube furnace and continuously introduce nitrogen into the tube furnace at a flow rate of 100 mL / min. After completely removing the air from the tube furnace, heat the furnace to 500°C at a heating rate of 5°C / min and maintain the temperature for 2 hours to obtain CuC.

[0063] Comparative Example 2

[0064] In this comparative example, the Cu-impregnated copper-based zeolite catalyst Cu / NaY was prepared using the following steps:

[0065] (1) Dissolve Cu(NO3)2·3H2O in deionized water, then add commercial NaY zeolite molecular sieve, sonicate for 10 min to fully disperse NaY zeolite molecular sieve in copper nitrate solution, and then shake at room temperature for 24 h to carry out sufficient ion exchange, controlling the mass ratio of NaY zeolite molecular sieve to Cu(NO3)2·3H2O to be 0.2:1.

[0066] (2) Centrifuge the reaction solution obtained by ion exchange in step (1), collect the solid product, wash the solid product with deionized water three times, and then dry it at 80°C overnight.

[0067] (3) Place the dried solid product obtained in step (2) into a tube furnace and continuously introduce nitrogen into the tube furnace at a flow rate of 100 mL / min. After completely removing the air from the tube furnace, heat the product to 500 °C at a heating rate of 5 °C / min and maintain the temperature for 2 hours to obtain the catalyst Cu / NaY.

[0068] Example 3

[0069] The operation of this embodiment is basically the same as that of embodiment 2. The only difference is that in step (1), the commercial NaY zeolite molecular sieve is replaced with the commercial HZSM-5 zeolite molecular sieve to prepare a copper-based carbon zeolite composite substrate catalyst CuC@HZSM-5 for the catalytic oxidation of complex VOCs.

[0070] Example 4

[0071] The operation of this embodiment is basically the same as that of Example 2. The only difference is that in step (1), the commercial NaY zeolite molecular sieve is replaced with the commercial 13X zeolite molecular sieve to prepare a copper-based carbon zeolite composite substrate catalyst CuC@13X for the catalytic oxidation of complex VOCs.

[0072] Example 5

[0073] The operation in this embodiment is basically the same as that in Example 2, except that the mass ratio of NaY zeolite molecular sieve to Cu(NO3)2·3H2O in dispersion A in step (1) is 0.3:1, thus preparing a copper-based carbon zeolite composite substrate catalyst CuC@NaY for the catalytic oxidation of complex VOCs. 3.3：1 .

[0074] Example 6

[0075] In this embodiment, the catalysts prepared in the aforementioned embodiments and comparative examples are characterized.

[0076] Scanning electron microscope (SEM) images, SEM-mapping images, nitrogen adsorption-desorption curves, and pore size distribution diagrams of the catalysts prepared in the aforementioned examples and comparative examples were tested. Figure 1 Figure (A) is a scanning electron microscope (SEM) image of CuC prepared in Comparative Example 1. Figure 1 Figure (B) is a SEM image of CuC@NaY prepared in Example 2. Figure 2 Figures (A) to (C) are SEM-mapping images of CuC prepared in Comparative Example 1. Figure 2 Figures (D) to (I) are SEM-mapping images of CuC@NaY prepared in Example 2. Figure 3 Figures (A) and (B) show the nitrogen adsorption-desorption curves and pore size distribution of CuC@NaY, CuC@HZSM-5, and CuC@13X prepared in Examples 2-4.

[0077] Depend on Figure 1 It can be seen that there are certain differences in morphology between CuC and CuC@NaY. The surface of CuC@NaY is relatively rougher and has a porous structure. Furthermore, the particle size of CuC@NaY is relatively smaller than that of CuC. The formation of the porous structure on the surface of CuC@NaY is mainly due to the porous structure of the carbon material formed by the pyrolysis of organic ligands during its preparation process. This porous carbon material is then coated onto the NaY zeolite molecular sieve. Figure 3It is evident that the CuC@NaY, CuC@HZSM-5, and CuC@13X prepared in Examples 2-4 all possess a hierarchical porous structure, primarily consisting of micropores with a pore size distribution within 2 nm, which mainly originate from the zeolite molecular sieve itself, as well as mesopores of 5-50 nm and macropores with a pore size exceeding 50 nm but less than 200 nm. These mesopores and macropores primarily originate from the pyrolysis and carbonization process of organic ligands during catalyst preparation. In other words, the catalyst prepared by the method described in this invention retains the microporous structure of the zeolite molecular sieve while also forming mesoporous and macroporous structures. Figure 2 It can be seen that the elemental distribution on the CuC@NaY surface is uniform, and no obvious agglomeration is observed, indicating that the active components on the CuC@NaY surface are highly dispersed. These characterization results demonstrate that the copper-based carbon zeolite composite substrate catalyst of this invention possesses highly dispersed active centers and a rich hierarchical porous structure.

[0078] Example 7

[0079] In this embodiment, the performance of CuC@NaY prepared in Example 2 and Cu / NaY prepared in Comparative Example 2 in catalytic oxidation of toluene was examined.

[0080] The CuC@NaY prepared in Example 2 and the Cu / NaY prepared in Comparative Example 2 were placed in a fixed bed and a mixed gas (20 vol% O2, 80 vol% N2) containing 1000 ppm toluene was introduced at a space velocity of 30000 mL·g. -1 ·h -1 Toluene in the mixed gas was catalytically oxidized under different temperatures under the specified conditions. After stabilization, the concentration of toluene in the fixed-bed outlet gas was measured. Specifically, the concentration of toluene in the outlet gas was determined online using a gas chromatograph equipped with an FID detector, and the toluene conversion rate was calculated using the following formula:

[0081] Toluene conversion rate = (Imported toluene concentration - Exported toluene concentration) / Imported toluene concentration × 100%

[0082] Figure 4 These are the performance curves of Cu / NaY and CuC@NaY catalytic oxidation of toluene prepared in Comparative Example 2 and Example 2. Figure 4It is evident that at temperatures below 325℃, the CuC@NaY catalyst exhibits a higher toluene conversion rate for toluene oxidation. However, above 325℃, the toluene conversion rates of Cu / NaY and CuC@NaY catalysts gradually converge, indicating that CuC@NaY possesses superior catalytic oxidation capability for toluene compared to Cu / NaY. This demonstrates that the present invention, by introducing porous carbon into a carbon-zeolite substrate with a hierarchical pore structure based on zeolite molecular sieves, and uniformly dispersing and anchoring nano-active metal oxides onto the carbon-zeolite substrate, effectively enhances the catalyst's ability to catalyze the oxidation of VOCs.

[0083] Example 8

[0084] In this embodiment, the catalysts prepared in the aforementioned examples and Comparative Example 1 were used in a VOCs thermocatalytic oxidation experiment to examine their performance in catalytic oxidation of VOCs.

[0085] (1) The CuC prepared in Comparative Example 1, the CuC@NaY-S prepared in Example 1, and the CuC@NaY prepared in Example 2 were placed in a fixed bed, and a mixed gas (20 vol% O2, 80 vol% N2) containing 1000 ppm VOCs (toluene) was introduced at a space velocity of 30000 mL·g. -1 ·h -1 Under certain conditions and at different temperatures, VOCs in the mixed gas were catalytically oxidized. After stabilization, the concentration of VOCs in the fixed-bed outlet gas was measured. Specifically, the concentration of VOCs in the outlet gas was measured online using a gas chromatograph equipped with an FID detector, and the VOCs conversion rate was calculated using the following formula:

[0086] VOCs conversion rate = (Imported VOCs concentration - Exported VOCs concentration) / Imported VOCs concentration × 100%

[0087] Figure 5 The figures show the performance curves of the catalytic oxidation of toluene by CuC prepared in Comparative Example 1, CuC@NaY-S prepared in Example 1, and CuC@NaY prepared in Example 2. Figure 5 It can be seen that, compared with the CuC prepared in Comparative Example 1, the CuC@NaY-S and CuC@NaY prepared in Examples 1 and 2 have stronger catalytic oxidation ability of toluene under the same temperature conditions; at the same time, compared with the CuC@NaY-S prepared in Example 1 by hydrothermal reaction under static conditions and subsequent carbonization operation, the CuC@NaY prepared in Example 2 by homogeneous hydrothermal reaction under stirring conditions and subsequent carbonization operation has better catalytic oxidation ability of toluene.

[0088] (2) The CuC@NaY, CuC@HZSM-5 and CuC@13X prepared in Examples 2-4 were placed in a fixed bed, and a mixed gas (20 vol% O2, 80 vol% N2) containing 1000 ppm VOCs (toluene or acetone) was introduced at a space velocity of 30000 mL·g. -1 ·h -1 Under certain conditions and at different temperatures, VOCs in the mixed gas were catalytically oxidized. After stabilization, the concentration of VOCs in the fixed-bed outlet gas was measured. Specifically, the concentration of VOCs in the outlet gas was measured online using a gas chromatograph equipped with an FID detector, and the VOCs conversion rate was calculated using the following formula:

[0089] VOCs conversion rate = (Imported VOCs concentration - Exported VOCs concentration) / Imported VOCs concentration × 100%

[0090] Figure 6 These are the performance curves of CuC@NaY, CuC@HZSM-5, and CuC@13X prepared in Examples 2-4 for the catalytic oxidation of toluene and acetone. Figures (A) and (B) show the performance curves for the catalytic oxidation of toluene and acetone, respectively. Figure 6 It can be seen that CuC@NaY, CuC@HZSM-5 and CuC@13X have excellent catalytic oxidation capabilities for toluene and acetone, especially CuC@NaY, which has relatively better catalytic oxidation capabilities for VOCs.

[0091] Example 9

[0092] In this embodiment, the CuC@NaY prepared in Example 5 is examined. 3.3：1 Performance of catalytic oxidation of complex VOCs.

[0093] CuC@NaY 3.3：1 The mixture was placed in a fixed bed and purged with either a gas mixture (20 vol% O2, 80 vol% N2) containing 1000 ppm toluene and 100 / 500 / 1000 ppm acetone, or a gas mixture (20 vol% O2, 80 vol% N2) containing 1000 ppm toluene, at a space velocity of 30000 mL·g⁻¹. -1 ·h -1 Under certain conditions and at different temperatures, VOCs in the mixed gas were catalytically oxidized. After stabilization, the concentration of VOCs (toluene or acetone) in the fixed-bed outlet gas was measured. Specifically, the concentration of VOCs in the outlet gas was measured online using a gas chromatograph equipped with an FID detector, and the VOCs conversion rate was calculated using the following formula:

[0094] VOCs conversion rate = (Imported VOCs concentration - Exported VOCs concentration) / Imported VOCs concentration × 100%

[0095] Figure 7 Figure (A) shows the CuC@NaY prepared in Example 5. 3.3：1 The conversion rates of toluene and acetone in complex VOCs are shown in the figure. In the figure, 1000T+100A(Ac) represents the conversion rate of acetone in a mixed gas with a toluene concentration of 1000 ppm and an acetone concentration of 100 ppm. The meanings of 1000T+500A(Ac) and 1000T+1000A(Ac) are similar. 1000T+100A(Tol) represents the conversion rate of toluene in a mixed gas with a toluene concentration of 1000 ppm and an acetone concentration of 100 ppm. The meanings of 1000T+500A(Tol) and 1000T+1000A(Tol) are similar. 1000Toluene represents the conversion rate of toluene in a mixed gas with a toluene concentration of 1000 ppm. As can be seen from the figure, the CuC@NaY prepared in Example 5... 3.3：1 It exhibits excellent catalytic oxidation performance for complex VOCs containing toluene and acetone.

[0096] Figure 7 Figure (B) shows the CuC@NaY prepared in Example 5. 3.3：1 The results of the CO2 selectivity test for complex VOCs, as shown in the figure, indicate that the CO2 selectivity decreases under the condition of coexistence of toluene and acetone, but when the temperature reaches 275℃, the CO2 selectivity of the two-component catalytic oxidation can be maintained at over 90%.

[0097] Example 10

[0098] In this embodiment, the CuC@NaY prepared in Example 5 is examined. 3.3：1 Stability and water resistance during catalytic oxidation of complex VOCs.

[0099] (1) CuC@NaY 3.3：1 The mixture was placed in a fixed bed and purged with a gas mixture (20 vol% O2, 80 vol% N2) containing 1000 ppm toluene and 500 ppm acetone at a space velocity of 30000 mL·g⁻¹. -1 ·h -1 Under these conditions, a continuous 72-hour test was conducted at 265℃. During the test, the concentration of VOCs (toluene or acetone) in the fixed-bed outlet gas was continuously monitored. Specifically, the concentration of VOCs in the outlet gas was determined online using a gas chromatograph equipped with an FID detector, and the VOCs conversion rate was calculated using the following formula:

[0100] VOCs conversion rate = (Imported VOCs concentration - Exported VOCs concentration) / Imported VOCs concentration × 100%

[0101] (2) CuC@NaY 3.3：1 The mixture was placed in a fixed bed and purged with a gas mixture (20 vol% O2, 80 vol% N2) containing 1000 ppm toluene and 500 ppm acetone at a space velocity of 30000 mL·g⁻¹. -1 ·h -1 The test was conducted continuously at 265℃ for 38 hours under the following conditions. Specific humidity conditions were as follows: at 0, 2, 6, 10, 14, 22, 26, 30, and 34 hours after the start of the reaction, the inlet water vapor concentration was adjusted to achieve humidity conditions in the fixed bed of 0% RH, 25% RH, 0% RH, 50% RH, 0% RH, 50% RH, 50% RH, and 0% RH. During the test, the concentration of VOCs (toluene or acetone) in the outlet gas of the fixed bed was continuously monitored. Specifically, the concentration of VOCs in the outlet gas was determined online using a gas chromatograph equipped with an FID detector, and the VOCs conversion rate was calculated using the following formula:

[0102] VOCs conversion rate = (Imported VOCs concentration - Exported VOCs concentration) / Imported VOCs concentration × 100%

[0103] Figure 8 Figures (A) and (B) are respectively CuC@NaY 3.3：1 Stability and water resistance test results of catalytic oxidation of complex VOCs. (From...) Figure 8 As shown in Figure (A), using CuC@NaY 3.3：1 When catalytically oxidizing the complex VOCs in this embodiment, the conversion rates of toluene and acetone remained essentially unchanged during continuous 72-hour operation. Figure 8 As shown in Figure (B), under a humidity condition of 25 RH%, CuC@NaY 3.3：1 During the catalytic oxidation of complex VOCs in this embodiment, a high catalytic oxidation conversion capacity for toluene and acetone was maintained throughout; under 50% RH humidity conditions, CuC@NaY was used. 3.3：1 In the catalytic oxidation of complex VOCs in this embodiment, CuC@NaY 3.3：1 The catalytic oxidation conversion ability to acetone remained essentially unchanged, while CuC@NaY 3.3：1 The catalytic oxidation ability to convert to toluene showed only a slight decrease, but after the humidity conditions returned to 25% RH, CuC@NaY 3.3：1 The catalytic oxidation capacity for toluene also recovers. Experimental results in this embodiment demonstrate that the catalyst prepared by the method described in this invention exhibits excellent stability and water resistance during the catalytic oxidation of VOCs.

[0104] Example 11

[0105] In this embodiment, the CuC prepared in Comparative Example 1 and the CuC@NaY prepared in Example 5 are examined. 3.3：1 Stability and water resistance during catalytic oxidation of toluene or acetone.

[0106] (1) CuC or CuC@NaY respectively 3.3：1 The mixture was placed in a fixed bed and a gas mixture (20 vol% O2, 80 vol% N2) containing 1000 ppm toluene or acetone was introduced at a space velocity of 30000 mL·g⁻¹. -1 ·h -1 Under the conditions specified (for CuC, the test temperatures for converting toluene and acetone are 275℃ and 230℃, respectively; for CuC@NaY...), the test temperatures for converting toluene and acetone are 275℃ and 230℃, respectively. 3.3：1 For the conversion of toluene and acetone, the test temperatures were 265℃ and 220℃, respectively, and the tests were conducted continuously for 72 hours. During the test, the concentration of VOCs (toluene or acetone) in the fixed bed outlet gas was continuously monitored. Specifically, the concentration of VOCs in the outlet gas was determined online using a gas chromatograph equipped with an FID detector, and the VOCs conversion rate was calculated using the following formula:

[0107] VOCs conversion rate = (Imported VOCs concentration - Exported VOCs concentration) / Imported VOCs concentration × 100%

[0108] (2) The CuC or CuC@NaY prepared in Comparative Example 1 or Example 5 were respectively used to prepare CuC or CuC@NaY 3.3：1 The mixture was placed in a fixed bed and a gas mixture (20 vol% O2, 80 vol% N2) containing 1000 ppm toluene or acetone was introduced at a space velocity of 30000 mL·g⁻¹. -1 ·h -1 Under the conditions specified in the test temperature (for CuC, the test temperatures for converting toluene and acetone are 275℃ and 230℃, respectively; for CuC@NaY...), the test temperatures for converting toluene and acetone are 275℃ and 230℃, respectively. 3.3：1 For the conversion of toluene and acetone, the test temperatures were 265℃ and 220℃, respectively, and the test was conducted continuously for 38 hours. Specific humidity conditions were as follows: at 0, 2, 6, 10, 14, 22, 26, 30, and 34 hours after the start of the reaction, the inlet water vapor concentration was adjusted to achieve humidity conditions in the fixed bed of 0% RH, 25% RH, 0% RH, 50% RH, 0% RH, 50% RH, 0% RH, 50% RH, 0% RH. During the test, the concentration of VOCs (toluene or acetone) in the outlet gas of the fixed bed was continuously monitored. Specifically, the concentration of VOCs in the outlet gas was determined online using a gas chromatograph equipped with an FID detector, and the VOCs conversion rate was calculated using the following formula:

[0109] VOCs conversion rate = (Imported VOCs concentration - Exported VOCs concentration) / Imported VOCs concentration × 100%

[0110] Figure 9 Figures (A) and (B) represent CuC and CuC@NaY, respectively. 3.3：1 Stability and water resistance test results of catalytic oxidation of toluene. Figure 10 Figures (A) and (B) represent CuC and CuC@NaY, respectively. 3.3：1 Stability and water resistance test results of catalytic oxidation of acetone. Figure 9 , 10 As shown in Figure (A), using CuC@NaY 3.3：1 When catalytically oxidizing toluene or acetone, the conversion rates of toluene and acetone remained essentially unchanged during continuous operation for 72 hours. (CuC@NaY) 3.3：1 The stability of CuC@NaY is significantly better than that of CuC. 3.3：1 The conversion rates of p-toluene and acetone were also significantly better than those of CuC; Figure 9 , 10 As shown in Figure (B), CuC@NaY 3.3：1 Its water resistance is also significantly better than CuC, and its performance can be completely reversibly restored after the influence of water vapor is removed.

[0111] Example 12

[0112] In this embodiment, a copper-based carbon zeolite composite substrate catalyst CuC@NaY was prepared for the catalytic oxidation of complex VOCs.

[0113] The operation of this embodiment is basically the same as that of embodiment 2, except that: in step (1), the mass ratio of NaY zeolite molecular sieve to Cu(NO3)2·3H2O is controlled to be 0.1:1; in step (2), the ratio of dispersion A to solution B is controlled so that the molar ratio of Cu(NO3)2·3H2O to H3BTC in the mixture obtained in this step is 1:1; in step (3), the reaction temperature of the hydrothermal reaction is controlled to be 85℃ and the reaction time is 36h; in step (4), the atmosphere introduced during the carbonization process is an oxygen-nitrogen mixture with an oxygen content of 0.5 vol.%, the carbonization temperature is controlled to be 400℃ and the carbonization time is 5h.

[0114] Example 13

[0115] In this embodiment, a copper-based carbon zeolite composite substrate catalyst CuC@NaY was prepared for the catalytic oxidation of complex VOCs.

[0116] The operation of this embodiment is basically the same as that of embodiment 2, except that: in step (1), the mass ratio of NaY zeolite molecular sieve to Cu(NO3)2·3H2O is controlled to be 1:1; in step (2), the ratio of dispersion A to solution B is controlled so that the molar ratio of Cu(NO3)2·3H2O to H3BTC in the mixture obtained in this step is 3:1; in step (3), the reaction temperature of the hydrothermal reaction is controlled to be 180℃ and the reaction time is 6h; in step (4), the atmosphere introduced during the carbonization process is carbon monoxide atmosphere, the carbonization temperature is controlled to be 600℃ and the carbonization time is 1h.

Claims

1. A method for preparing a copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs, characterized in that, Includes the following steps: (1) Dissolve the metal coordination ion salt in a mixed solvent of water and organic solvent to obtain solution A. The metal coordination ion salt includes at least a first coordination metal ion salt, which is a water-soluble copper salt. Disperse the zeolite molecular sieve fully in solution A and let it stand to allow for sufficient ion exchange to obtain dispersion A. In dispersion A, the mass ratio of zeolite molecular sieve to metal coordination ion salt is (0.1~1):

1. The zeolite molecular sieve is a Y-type zeolite molecular sieve, an X-type zeolite molecular sieve, or a ZSM-type zeolite molecular sieve. The organic ligand 1,3,5-benzenetricarboxylic acid was dissolved in a mixed solvent of water and organic solvent to obtain solution B; (2) Add solution B to dispersion A, mix thoroughly, and control the ratio of dispersion A to solution B so that Cu 2+ The molar ratio of 1,3,5-benzenetricarboxylic acid to 1,3,5-benzenetricarboxylic acid is (0.2~3):1; (3) Transfer the mixture obtained in step (2) to the reactor and carry out a full hydrothermal reaction at 80~160 °C. During the hydrothermal reaction, the organic ligands and the metal coordination ions in the zeolite molecular sieve undergo coordination reaction, and the metal-organic framework is formed on the zeolite molecular sieve to form a structure that covers the zeolite molecular sieve. Centrifuge the obtained reaction solution, collect the solid product, wash and dry the solid product to obtain the composite intermediate. (4) The composite intermediate obtained in step (3) is subjected to full carbonization at 350~800 °C in an inert atmosphere, a reducing atmosphere or a weak oxidizing atmosphere with an oxygen content of less than 1.0 vol.%. During the carbonization process, the metal-organic framework in the composite intermediate is transformed into porous carbon containing nano-active metal oxides, and the porous carbon and zeolite molecular sieve form a carbon-zeolite substrate with a hierarchical pore structure. The nano-active metal oxides are uniformly dispersed and anchored on the carbon-zeolite substrate, thus obtaining the copper-based carbon-zeolite composite substrate catalyst.

2. The method for preparing the copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs according to claim 1, characterized in that, The organic solvent in step (1) is ethanol, or a mixture of ethanol and... N,N -Dimethylformamide.

3. The method for preparing the copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs according to claim 2, characterized in that, When the organic solvent in step (1) is ethanol, the volume ratio of water to ethanol in the mixed solvent of water and organic solvent is 1:(0.8~1.2); when the organic solvent in step (1) is ethanol and N,N When dimethylformamide is used, water, ethanol and... N,N The volume ratio of dimethylformamide is 1:(0.8~1.2):(0.8~1.2).

4. The method for preparing the copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs according to claim 1, characterized in that, Step (3) The hydrothermal reaction is carried out under stirring conditions, and the hydrothermal reaction time is controlled to be 6~36 h.

5. The method for preparing the copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs according to claim 1, characterized in that, In step (4), the carbonization time is controlled to be 1~5 h.

6. The method for preparing the copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs according to claim 1, characterized in that, The metal coordination ion salt also includes a second coordination metal ion salt, which includes at least one of water-soluble manganese salt, water-soluble cobalt salt, and water-soluble iron salt.

7. The method for preparing the copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs according to claim 1, characterized in that, The pore structure of the carbon-zeolite substrate with hierarchical pore structure formed in step (4) consists of micropores with a pore size of no more than 2 nm, mesopores with a pore size of 5 to 50 nm, and macropores with a pore size of more than 50 nm but less than 200 nm.

8. A copper-based carbon zeolite composite substrate catalyst for the catalytic oxidation of complex VOCs prepared by the method of any one of claims 1 to 7.

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