Preparation of modified zeolite catalyst, and modified zeolite catalyst and gas purification method using same

Abstract

Provided are the preparation of a modified zeolite catalyst, a modified zeolite catalyst and an ozone purification method. The preparation is implemented by using a method comprising: mixing a metal salt solution with zeolite to form a non-Newtonian fluid mixture, drying the mixture by using microwaves, and finally calcining same, so as to obtain a zeolite catalyst. In the preparation method, microwaves are used to dry the mixture of the metal salt solution and the zeolite, the drying time is short, and the evaporation of water is quick, thereby maintaining the state of metal cations in a zeolite framework, and preventing catalyst particles (metal clusters) from being deintercalated from the zeolite framework and becoming aggregated. The zeolite catalyst prepared by using the preparation method contains metal clusters which are uniformly dispersed, and comprises an active component composed of a plurality of metal cations. The zeolite catalyst plays a crucial role during the catalytic decomposition process of ozone, and improves the low-temperature catalytic oxidation efficiency of O3.

Description

Preparation of modified zeolite catalyst, modified zeolite catalyst and gas purification method thereof Technical Field

[0001] The invention belongs to the field of modified zeolite preparation, and in particular relates to the preparation of a modified zeolite catalyst, a modified zeolite catalyst and a method for purifying gas thereof. Background Art

[0002] Production and daily life generate a large amount of gaseous pollutants, which can pose serious risks to human health and the climate. For example, organic compounds (VOCs) in the air undergo a series of chemical reactions under sunlight, generating ozone, which can contribute to global warming, affect air quality and the Earth's ecosystem, and harm human health. Nitrogen-containing waste gases generated during chemical production not only impact the surrounding environment and human health but also damage the ozone layer. Sulfur-containing pollutants emitted during the production of fossil fuels such as petroleum, if released into the atmosphere in gaseous form (such as gaseous sulfur dioxide and hydrogen sulfide), are highly likely to trigger natural disasters such as acid rain.

[0003] Common gas catalytic purification materials include activated carbon, precious metal-loaded catalysts, transition metal oxides, and zeolite molecular sieves. Activated carbon is low-cost and readily available, but poses a safety risk of explosion and is susceptible to structural erosion after long-term use. Precious metal-loaded catalysts offer high purification efficiency but are expensive. Transition metal oxides are inexpensive and highly active under dry conditions, but can deactivate catalytic sites over long periods of operation. Zeolites are typical microporous inorganic materials composed of AlO4 and SiO4 tetrahedrons. They possess micro-mesoporous channels and ample catalytically active sites, and are increasingly recognized as suitable materials for gas catalytic purification, attracting widespread attention.

[0004] Different from transition metal oxides, the high specific surface area (up to 800 m 2 Gases on zeolites with large pore volumes and specialized acidic sites undergo both physical adsorption within the pores and catalytic decomposition at Lewis acid sites (LAS). The tiny pores in the zeolite, similar in size to gas molecules, facilitate interaction between gas molecules and LAS. According to adsorption theory, this interaction is more pronounced at lower temperatures. Studies have found that the content and dispersion of LAS are related to the zeolite framework structure, silicon-aluminum ratio, cation type, and ion exchange method. The type and distribution of metal cations are the primary factors influencing catalytic activity. Therefore, by ion-modifying the zeolite and controlling the state of cations at the zeolite exchange sites, conversion efficiency can be significantly adjusted and selected.

[0005] The salt solution stirring and impregnation method is a traditional liquid-phase zeolite modification method. The zeolite is immersed in a prepared metal salt solution, and ion exchange is promoted by heating and stirring. It is then repeatedly washed with deionized water and dried and calcined to obtain a modified zeolite powder. This technology has the following disadvantages: ① The modification process is complicated, the amount of waste liquid is large, it is easy to cause environmental pollution, and it is not suitable for industrial applications; ② The degree of ion exchange is low, it is difficult to ensure the content of catalytically active components, and the metal in the modified zeolite framework is a single ion, with low catalytic activity; ③ The slow evaporation of water vapor during the drying process will cause the metal ions to detach from the zeolite framework along with the water molecules and agglomerate on the zeolite surface.

[0006] Furthermore, conventional gas purification catalysts in the prior art have low low-temperature catalytic activity, are prone to irreversible deactivation over long-term use, and exhibit poor regeneration performance. Existing modified zeolites have low metal ion exchange rates and use single metal ions as active components, resulting in low catalytic activity. Furthermore, there are currently no zeolite catalysts with uniform and highly dispersed metal ion clusters. Summary of the Invention

[0007] To address the above-mentioned issues, the present invention provides a method for preparing a modified zeolite catalyst, a modified zeolite catalyst, and gas purification methods thereof. The zeolite catalyst prepared by the preparation method comprises clusters of multiple, uniformly distributed metal cations as catalytically active components. The metal clusters in the zeolite catalyst exhibit enhanced catalytic activity, playing a crucial role in catalytic decomposition and improving the catalyst's low-temperature catalytic oxidation efficiency.

[0008] The present invention is achieved through the following technical solutions:

[0009] The first aspect of the present invention is to provide a method for preparing a modified zeolite catalyst, which adjusts the metal clusters in the modified zeolite framework, including mixing a metal salt solution with zeolite to form a non-Newtonian fluid mixture, using microwave drying to dry the mixture, and finally calcining to obtain the zeolite catalyst.

[0010] Furthermore, the preparation method specifically comprises the following steps:

[0011] Prepare metal salt solution and zeolite in a specified ratio respectively;

[0012] Preparing a non-Newtonian fluid mixture: mixing the metal salt solution and the zeolite with stirring to obtain the non-Newtonian fluid mixture;

[0013] drying the non-Newtonian fluid mixture by microwave;

[0014] The dried non-Newtonian fluid mixture is calcined to obtain the zeolite catalyst.

[0015] Furthermore, configuring the metal salt solution specifically includes:

[0016] Determine the amount of metal salt: Calculate the mass of the metal salt based on the silicon-aluminum ratio and the theoretical ion exchange degree;

[0017] Determine the amount of water required to prepare the metal salt solution: add deionized water dropwise to an equal amount of the zeolite and stir evenly until the mixture becomes a non-Newtonian fluid. The amount of water added is the amount of water required to prepare the metal salt solution.

[0018] mixing the metal salt with the amount of water to obtain the metal salt solution;

[0019] Furthermore, the molar ratio of the metal salt to the zeolite is in the range of 0 to 5, excluding 0.

[0020] Furthermore, the metal salt includes nitrate and / or acetate.

[0021] Furthermore, the metal clusters include: Mn 2+ 、Mn2O 2+ 、Mn3O3 2+ 、[AlO2] + 、[MnCuO] 2+ 、[Mn2CuO3] 2+ and [FeCoO] 2+ One, two or more of the following.

[0022] Furthermore, microwave drying the non-Newtonian fluid mixture specifically includes:

[0023] The mixture is evenly spread into a crucible, an evaporating dish, or a stainless steel beaker, and then rapidly heated in a microwave reactor at a power of 100-1000W for 30s-30min. During the microwave heating process, water in the mixture is rapidly evaporated, locking the polymer of metal salt ions in the zeolite pores to prevent them from adhering to the zeolite surface due to evaporation of water. At this time, at least one initial cluster is evenly distributed in the pores of the zeolite powder, and the initial cluster includes metal ions and nitrate ions.

[0024] A second aspect of the present invention is to provide a modified zeolite catalyst, wherein the zeolite catalyst is prepared using the above-mentioned method for preparing a modified zeolite catalyst, wherein a plurality of metal clusters are uniformly distributed in the pores of the zeolite powder in the zeolite catalyst; the metal clusters include metal ions and compatible oxygen atoms;

[0025] The number of the metal ions is at least 1; preferably, the number of the metal ions is 1-5.

[0026] The third aspect of the present invention is to provide an ozone purification method, wherein the ozone purification method uses the above-mentioned zeolite catalyst to purify ozone; the zeolite catalyst is heated at -10 to 300 ° C and the air velocity is 1×10 4 ~2×10 6 h -1 Ozone is removed under the conditions of , and the O3 removal rate is maintained at ≥ 90% for up to 2000min.

[0027] Furthermore, the zeolite catalyst is at room temperature and the flow rate is 1.0 L min -1 Under the conditions of 3000 ℃ and 8000 ℃, the O3 removal rate is maintained at ≥90% for up to 2000 minutes.

[0028] Furthermore, the scope of ozone purification includes low-temperature, large-flow aircraft cabin ozone removal, factory ozone waste gas treatment, and indoor ozone purification.

[0029] Furthermore, the zeolite catalyst forms include but are not limited to powder catalysts, granular catalysts (made by mixing with an adhesive) and monolithic catalysts (extruded or coated).

[0030] The first aspect of the present invention provides a method for preparing a modified zeolite catalyst, comprising mixing a metal salt solution with a zeolite to form a non-Newtonian fluid mixture, drying the mixture using microwaves, and finally calcining to obtain the zeolite catalyst. The preparation method adjusts the metal clusters within the modified zeolite framework, calculates the amount of metal salt based on the silicon-aluminum ratio and the theoretical ion exchange degree, and then calculates the amount of water in the metal salt solution based on the target exchange state, so that the polymer formed by the metal cations and water molecules is evenly distributed in the zeolite pores, thereby achieving adjustable and controllable metal ion exchange degree. The preparation method uses microwaves to dry the mixture of the metal salt solution and the zeolite, which has a short drying time and fast water evaporation. It can retain the state of the metal cations in the zeolite framework and prevent the catalyst particles (metal clusters) from escaping from the zeolite framework and aggregating. In addition, the preparation method adopts a simple mixing and stirring process, avoiding a long heating and stirring process. The catalyst preparation time is greatly shortened, and the energy consumption of the catalyst preparation process is greatly reduced.

[0031] The second aspect of the present invention provides a modified zeolite catalyst, which has a cluster of multiple metal cations as catalytically active components, and is evenly distributed. Compared with traditional single cation exchange modified zeolite catalysts, the metal clusters of the zeolite catalyst have higher catalytic activity and play a vital role in the catalytic decomposition of ozone (O3), improving the catalyst's low-temperature catalytic oxidation efficiency of O3. The zeolite catalyst has excellent low-temperature catalytic activity and stability, and can be used at room temperature with a flow rate of 1.0 L·min -1Under the conditions of 150°C, the O3 removal rate was maintained at ≥90% for up to 2000 minutes. In addition, the catalyst has excellent regeneration performance and can restore catalytic activity after low-temperature regeneration at 150°C.

[0032] The ozone purification method provided by the third aspect of the present invention can maintain an O3 removal rate of ≥90% for up to 2000 minutes; it is suitable for ozone removal in low-temperature, high-flow aircraft cabins, factory ozone waste gas treatment, indoor ozone purification, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 shows the zeolite catalysts (D1-Mn-FAU and D2-Mn-FAU) prepared by a modified zeolite catalyst preparation method in the embodiment of the present invention and the catalysts (T1-Mn-FAU and T2-Mn-FAU) prepared by the conventional liquid phase modification method, under an ozone concentration of 20 ppm, room temperature, and a flow rate of 1.0 L min -1 Schematic diagram of ozone conversion performance test results under conditions.

[0034] Figure 2 shows the zeolite catalyst D2-Mn-FAU prepared by the preparation method of a modified zeolite catalyst in an embodiment of the present invention at an ozone concentration of 20 ppm, room temperature, and a flow rate of 1.0 L·min -1 Regeneration performance test curve under conditions.

[0035] FIG3 is a schematic diagram showing a comparison of XRD characterization results of zeolite catalysts (D1-Mn-FAU and D2-Mn-FAU) prepared by a method for preparing a modified zeolite catalyst in an embodiment of the present invention and zeolite raw powder (FAU zeolite).

[0036] Figure 4 shows the zeolite catalyst single metal cluster catalyst (D1-Mn-FAU) and multi-metal cluster catalyst (D1-Mn2Cu-FAU) obtained by the preparation method of the embodiment of the present invention at an ozone concentration of 20 ppm, room temperature, and a flow rate of 1.0 L min -1 Schematic diagram of efficiency curve under different conditions.

[0037] FIG5 is a schematic diagram showing polyatomic metal clusters located in the zeolite framework structure in a zeolite catalyst prepared by a method for preparing a modified zeolite catalyst in an embodiment of the present invention.

[0038] FIG6 is a schematic diagram showing the calculation results of the reaction energy and transition state energy barrier of the modified catalyst obtained by the preparation method described in this embodiment using the CASTEP (plane wave pseudopotential method) module in Materials studio (material simulation calculation software). DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] On the contrary, the present invention covers any alternatives, modifications, equivalents, and solutions that fall within the spirit and scope of the present invention as defined by the claims. Furthermore, to facilitate a better understanding of the present invention, certain specific details are described in detail below in the detailed description of the present invention. Those skilled in the art will be able to fully understand the present invention without these details.

[0041] The following examples serve to illustrate the present invention. In the examples, unless otherwise indicated, parts are by weight, percentages are by weight, and temperatures are in degrees Celsius. The relationship between parts by weight and parts by volume is the same as the relationship between grams and cubic centimeters.

[0042] The term "MFI" stands for "Mobil five Instructure" in English, and both MFI and FUA are types of zeolite topology.

[0043] The first aspect of the embodiment of the present invention proposes a preparation method for a modified zeolite catalyst, which adjusts the metal clusters in the modified zeolite framework, including mixing a metal salt solution with zeolite to form a non-Newtonian fluid mixture, using microwave drying the mixture, and finally calcining to obtain the modified zeolite catalyst.

[0044] The preparation method of a modified zeolite catalyst proposed in the first aspect of the embodiment of the present invention includes mixing a metal salt solution with zeolite to form a non-Newtonian fluid mixture, drying the mixture using microwaves, and finally calcining to obtain the modified zeolite. The preparation method adjusts the metal clusters within the modified zeolite framework, calculates the amount of metal salt based on the silicon-aluminum ratio and the theoretical ion exchange degree, and then calculates the amount of water in the metal salt solution based on the target exchange state, so that the polymer formed by the metal cations and water molecules is evenly distributed in the zeolite pores, thereby achieving adjustable and controllable metal ion exchange degree. The preparation method uses microwaves to dry the mixture of the metal salt solution and zeolite. The drying time is short and the water evaporates quickly, which can retain the state of the metal cations in the zeolite framework and prevent the catalyst particles (metal clusters) from escaping from the zeolite framework and aggregating. In addition, the preparation method adopts a simple mixing and stirring process, avoiding the long-term heating and stirring process. The catalyst preparation time is greatly shortened, and the energy consumption of the catalyst preparation process is greatly reduced.

[0045] In some embodiments of the present invention, a method for preparing a modified zeolite catalyst is provided, the preparation method specifically comprising the following steps:

[0046] S1: Prepare metal salt solution and zeolite in a specified ratio;

[0047] S2 preparing a non-Newtonian fluid mixture: mixing the metal salt solution prepared in S1 with the zeolite and stirring to obtain a non-Newtonian fluid mixture;

[0048] S3 Microwave drying of non-Newtonian fluid mixtures;

[0049] S4 calcining the dried non-Newtonian fluid mixture to obtain a modified zeolite catalyst.

[0050] In some embodiments of the present invention, in the above step S1, preparing the metal salt solution specifically includes:

[0051] S1.1 Determine the amount of metal salt: Calculate the mass of the metal salt based on the silicon-aluminum ratio and the theoretical degree of ion exchange. The amount of metal salt added is calculated based on the silicon-aluminum ratio of the zeolite and the theoretical exchange rate. The silicon-aluminum ratio of the zeolite is any number greater than 1, and the target exchange state is a metal cluster with 1-5 metal ions. The amount of metal salt used is small, the cost is low, no waste liquid is generated, and it is environmentally friendly.

[0052] S1.2 Determine the amount of water required for the metal salt solution: Add deionized water dropwise to an amount of zeolite equal to that in S2, stirring evenly to form a non-Newtonian fluid. The amount of deionized water added at this point is the amount required to prepare the metal salt solution.

[0053] S1.3 Mix the metal salt in S1.1 with the water in S1.2 to obtain a metal salt solution. Mixing the calculated metal salt solution with the zeolite ensures the zeolite's metal ion loading while enabling adjustable and controllable ion exchange. The type and aggregation state of the metal ions in the zeolite pores are determined by the calculated dosage.

[0054] In some embodiments of the present invention, in the above-mentioned step S2, the specific content includes adding the prepared metal salt solution dropwise into the zeolite while stirring evenly so that the mixture is in a non-Newtonian fluid state; the purpose of this operation is to allow the metal salt ions and water to form charged ionic polymers that are evenly distributed in the zeolite pores.

[0055] In some embodiments of the present invention, taking a single metal cation exchange, nitrate, as an example, the required amount of metal salt is calculated as follows:

[0056] The molecular formula of the zeolite molecular sieve used is H(AlO2)(SiO2) n , n is any number not less than 1; the theoretical exchange of metal clusters is [M x O y ] z+ , M is metal, 0<x≤5、0≤y≤5、z> 0, x, y, z are all integers;

[0057] To modify 1 mol of zeolite molecular sieve, (x / z) mol of metal cations are required, and (x / z) mol of nitrate (or (x / z) mol of acetate) are required.

[0058] The mass of nitrate was calculated based on the molar masses of zeolite molecular sieve and nitrate.

[0059] In some embodiments of the present invention, the molar ratio of the metal salt to the zeolite is in the range of 0 to 5, excluding 0.

[0060] In some embodiments of the present invention, the metal salt is nitrate and / or acetate. Both types of salts are easily soluble in water, and the metals in the metal salt solution after dissolving in water are all free metal ions, which facilitates subsequent ion exchange.

[0061] In some embodiments of the present invention, the nitrates include nitrates of manganese, cobalt, copper, cerium, tin, lanthanum, praseodymium, samarium, europium, gadolinium, potassium, calcium, zinc, magnesium, and nickel.

[0062] In some embodiments of the present invention, the acetate salts include acetate salts of manganese, cobalt, copper, cerium, tin, lanthanum, praseodymium, samarium, europium, gadolinium, potassium, calcium, zinc, magnesium, and nickel.

[0063] In some embodiments of the present invention, the concentration of the metal salt solution is within the saturation concentration range.

[0064] In some embodiments of the present invention, in step S3, microwave drying the non-Newtonian fluid mixture specifically includes:

[0065] The non-Newtonian fluid mixture is evenly spread into a crucible, an evaporating dish or a stainless steel beaker, and then rapidly heated in a microwave reactor at a power of 100-1000W for 30s-30min;

[0066] During microwave heating, the mixture rapidly evaporates water, locking the metal salt ion polymers within the zeolite pores and preventing them from adhering to the zeolite surface as the water evaporates. At this point, the zeolite powder pores are uniformly distributed with 1-5 initial clusters consisting of metal ions and nitrate ions. Microwave drying, under high temperature and high pressure, rapidly evaporates water, locking the metal ion polymers within the zeolite pores, preventing the metal ions from migrating with water molecules and preserving their aggregated state and position. This specific number of metal polymers enhances catalytic activity and improves the low-temperature ozone conversion performance of the zeolite catalyst.

[0067] In some embodiments of the present invention, in the above step S4, calcining the dried non-Newtonian fluid mixture specifically includes:

[0068] The dried powder is calcined in an oven, hot plate, heating mantle, muffle furnace or tube furnace at a temperature of 300-1200°C for 1-12 hours. The calcination removes nitrate ions (the product of the exchange of nitrate with H ions in the zeolite is HNO3, which is decomposed and removed during the calcination process) and remaining water molecules in the zeolite pores, resulting in metal clusters formed by metal ions and oxygen atoms. The zeolite catalyst powder obtained after calcination has high catalytic activity.

[0069] A second aspect of an embodiment of the present invention provides a modified zeolite catalyst, wherein the zeolite catalyst is prepared using the above-mentioned method for preparing a modified zeolite catalyst, wherein a plurality of metal clusters are uniformly distributed in the pores of the zeolite powder in the zeolite catalyst; the metal clusters include metal ions and compatible oxygen atoms;

[0070] The number of metal ions is at least 1; preferably, the number of metal ions is 1-5.

[0071] The modified zeolite catalyst provided in the second aspect of the embodiment of the present invention has a cluster of multiple metal cations as catalytically active components, and the clusters are evenly distributed. Compared with the traditional modified zeolite catalyst with a single cation exchange, the metal clusters of the zeolite catalyst have higher catalytic activity and play a vital role in the catalytic decomposition of ozone (O3), thereby improving the catalyst's low-temperature catalytic oxidation efficiency of O3. The zeolite catalyst has excellent low-temperature catalytic activity and stability, and can be used at room temperature with a flow rate of 1.0 L·min -1 Under the conditions of 100% CO₂, the O₃ removal rate can be maintained at ≥90% for up to 2000 min. In addition, the catalyst has excellent regeneration performance and can restore catalytic activity after low-temperature regeneration at 150°C.

[0072] The third aspect of the embodiment of the present invention provides an ozone purification method, which uses the above-mentioned zeolite catalyst to purify ozone; the zeolite catalyst is heated at -10~300℃ and the air velocity is 1×10 4 ~2×10 6 h -1 Ozone is removed under the conditions of , and the O3 removal rate is maintained at ≥ 90% for up to 2000min.

[0073] The ozone purification method provided in the third aspect of the embodiment of the present invention can maintain an O3 removal rate of ≥90% for up to 2000 minutes; it is suitable for ozone removal in low-temperature, high-flow aircraft cabins, factory ozone waste gas treatment, indoor ozone purification, etc.

[0074] In some specific embodiments of the present invention, the zeolite catalyst is heated at room temperature and the flow rate is 1.0 L·min -1 Under the conditions of 3000 ℃ and 8000 ℃, the O3 removal rate is maintained at ≥90% for up to 2000 minutes.

[0075] In some specific embodiments of the present invention, the scope of ozone purification includes low-temperature, large-flow aircraft cabin ozone removal, factory ozone waste gas treatment, and indoor ozone purification.

[0076] In some specific embodiments of the present invention, the zeolite catalyst forms include but are not limited to powder catalysts, granular catalysts (made by mixing with a binder), and monolithic catalysts (extruded or coated).

[0077] The technical solution of the present invention is further described below with reference to embodiments. Example 1

[0078] A method for preparing a modified zeolite catalyst comprises the following steps:

[0079] ①Measure FAU zeolite and 50wt% manganese nitrate solution;

[0080] ② Determine the amount of water required for modification: Weigh 10g of zeolite and add deionized water dropwise to the zeolite powder while stirring evenly until the mixture becomes a non-Newtonian fluid. At this time, add 10.0ml of deionized water and record the required amount of water.

[0081] ③ Calculate the amount of zeolite and manganese nitrate solution: Based on the silicon-aluminum ratio of the zeolite used and the theoretical exchange rate, weigh 10g of zeolite and 4.26g of 50wt.% manganese nitrate solution to prepare 10ml of solution.

[0082] ④ Add the prepared manganese nitrate solution dropwise into the zeolite powder while stirring evenly to make it into a non-Newtonian fluid state.

[0083] ⑤ Spread the mixture evenly into an evaporating dish and quickly dry it using a microwave reactor at 800 W power for 4 minutes.

[0084] ⑥ The dried powder was calcined in a muffle furnace at 350°C for 3 hours at a heating rate of 2°C / min to obtain modified zeolite catalyst powder. Example 2

[0085] A method for preparing a modified zeolite catalyst. The method for preparing the modified zeolite catalyst in this embodiment is basically the same as that in Example 1, except that the theoretical exchange rate of metal ions in this embodiment is 3.0, and the theoretical exchanged metal clusters are [Mn3O3] 2+ . Example 3

[0086] A method for preparing a modified zeolite catalyst. The method for preparing the modified zeolite catalyst in this embodiment is basically the same as that in Example 1, except that the zeolite powder used is tZSM-5 with an MFI topological structure. Example 4

[0087] A method for preparing a modified zeolite catalyst. The method for preparing the modified zeolite catalyst in this embodiment is basically the same as that in Example 1, except that the drying power of the microwave reactor is 600 W and the drying time is 8 minutes. Example 5

[0088] A method for preparing a modified zeolite catalyst. The method for preparing the modified zeolite catalyst in this embodiment is basically the same as that in Example 1, except that the mixture is placed in an oven and dried at 160° C. for 2 h. Example 6

[0089] A method for preparing a modified zeolite catalyst is provided. The method for preparing the modified zeolite catalyst in this embodiment is substantially the same as that in Example 1, except that the dried powder is calcined at 450° C. for 3 h in a muffle furnace. Example 7

[0090] A method for preparing a modified zeolite catalyst. The method for preparing the modified zeolite catalyst in this embodiment is basically the same as that in Example 1, except that the theoretical exchange cluster is [Mn2CuO3] 2+ . Example 8

[0091] A method for preparing a modified zeolite catalyst. The method for preparing the modified zeolite catalyst in this embodiment is basically the same as that in Example 1, except that:

[0092] The preparation method further comprises the step ⑦ of grinding the zeolite catalyst powder, uniformly mixing the obtained zeolite fine powder with an adhesive, an additive, and deionized water in a certain proportion, forming the powder into a spherical or cylindrical shape, and drying and calcining the granular zeolite catalyst. Example 9

[0093] A method for preparing a modified zeolite catalyst. The method for preparing the modified zeolite catalyst in this embodiment is basically the same as that in Example 1, except that:

[0094] The preparation method also includes step ⑦ grinding the zeolite catalyst powder, mixing the zeolite fine powder with an adhesive, an additive, and deionized water in a certain proportion, extruding it into a honeycomb shape using a mold under a certain pressure, and drying and calcining it to obtain an extruded honeycomb zeolite catalyst. Example 10

[0095] A method for preparing a modified zeolite catalyst. The method for preparing the modified zeolite catalyst in this embodiment is basically the same as that in Example 1, except that:

[0096] The preparation method also includes step 7: grinding the zeolite catalyst powder, uniformly mixing the zeolite fine powder with an adhesive, an additive, and deionized water in a predetermined proportion to form a slurry of suitable viscosity, immersing a pre-prepared support in the slurry for 10 seconds to 30 minutes, removing the support, drying it, and calcining it to obtain a coated monolithic catalyst. Supports include metal supports, cordierite supports, glass, or ceramic fiber supports. Comparative Example 1

[0097] Catalyst samples (T1-Mn-FAU and T2-Mn-FAU) were obtained by salt solution stirring impregnation method (the existing traditional liquid phase modification method).

[0098] Next, the modified zeolite catalysts prepared in Examples 1 to 10 and Comparative Example 1 were analyzed.

[0099] As shown in FIG1 , the catalyst samples (T1-Mn-FAU and T2-Mn-FAU) obtained by the salt solution stirring impregnation method (the existing traditional liquid phase modification method) in Comparative Example 1 and the zeolite catalysts (D1-Mn-FAU and D2-Mn-FAU) prepared by the preparation method of Example 1 were subjected to an ozone concentration of 20 ppm, room temperature, and a flow rate of 1.0 L·min. -1 Schematic diagram of ozone conversion performance test results under different conditions. As shown in Figure 1, the modified sample was compressed using a tablet press, then ground into fine particles. A 40-60 mesh granular catalyst was screened to select. 30-1000 mg of the granular catalyst was then loaded into the reactor. The ozone concentration at the reactor inlet was maintained at 20 ppm, and the ozone concentration C at the reactor outlet was monitored and recorded in real time. The ozone conversion efficiency curve was plotted with time as the x-axis and 1-C / 20 as the y-axis. A comparison of the ozone purification efficiencies of zeolite catalysts obtained using different methods (salt solution stirring and impregnation method and DT method) shows that the sample obtained using the salt solution stirring and impregnation method rapidly deactivated after a period of testing, with catalytic activity far lower than that of D1-Mn-FAU and D2-Mn-FAU.

[0100] As shown in FIG2 , the zeolite catalyst D2-Mn-FAU prepared by the preparation method of a modified zeolite catalyst in Example 1 was subjected to an ozone concentration of 20 ppm, room temperature, and a flow rate of 1.0 L·min -1 As shown in Figure 2, the modified zeolite material can be regenerated under heating conditions at 150°C and its catalytic activity can be restored well.

[0101] Figure 3 shows a schematic diagram comparing the XRD characterization results of zeolite catalysts (D1-Mn-FAU and D2-Mn-FAU) prepared using the method for preparing a modified zeolite catalyst according to an embodiment of the present invention and zeolite powder (FAU zeolite). As shown in Figure 3, there is no significant difference in the XRD curves of the samples before and after modification, indicating that the modification process does not damage the zeolite framework.

[0102] As shown in FIG4 , the single metal cluster catalyst (D1-Mn-FAU) and the multi-metal cluster catalyst (D1-Mn2Cu-FAU) prepared by the preparation method of a modified zeolite catalyst of Example 1 and Example 7 were subjected to an ozone concentration of 20 ppm, room temperature, and a flow rate of 1.0 L·min -1 Figure 4 shows the ozone conversion performance test results under different conditions. As shown in Figure 4, the synergistic effect between the various elements in the catalyst can improve its catalytic performance.

[0103] As shown in Figure 5, a schematic diagram of the polyatomic metal clusters located in the zeolite framework structure in the zeolite catalyst prepared by the preparation method of Example 2. As can be seen from Figure 5, in the zeolite framework structure, a negatively charged [AlO2] - It can attract ion clusters composed of metal ions and oxygen atoms and become the location of metal clusters.

[0104] Referring to Figure 6, the results of the reaction energy and transition state energy barrier calculations using the CASTEP (plane wave pseudopotential method) module in Materials studio (material simulation software) for the modified zeolite catalysts prepared in Example 1 and Example 2 are shown in Figure 6. 2+ 、Mn2O 2+ 、Mn3O3 2+ In a zeolite catalyst model with Mn exchange, the adsorption energy of ozone molecules increases with the number of Mn atoms, while the transition state energy barrier of the rate-limiting step decreases with the increase in the number of Mn atoms. A metal cluster model consisting of three Mn atoms in the zeolite pores exhibits higher ozone adsorption energy and lower energy barriers for the rate-limiting step, resulting in higher catalytic activity than single-atom catalytic active sites.

[0105] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing a modified zeolite catalyst, characterized in that: The preparation method adjusts the metal clusters in the modified zeolite framework, including mixing a metal salt solution with zeolite to form a non-Newtonian fluid mixture, drying the mixture with microwaves, and finally calcining to obtain the zeolite catalyst.

2. The method for preparing a modified zeolite catalyst according to claim 1, characterized in that: The preparation method specifically comprises the following steps: The metal salt solution and the zeolite are respectively prepared in a specified ratio; Preparing a non-Newtonian fluid mixture: mixing the metal salt solution and the zeolite with stirring to obtain the non-Newtonian fluid mixture; Microwave drying the non-Newtonian fluid mixture; The non-Newtonian fluid mixture after drying is calcined to obtain the zeolite catalyst.

3. The method for preparing a modified zeolite catalyst according to claim 2, characterized in that: The metal salt solution is configured to specifically include: Determine the amount of metal salt: Calculate the mass of the metal salt based on the silicon-aluminum ratio and the theoretical ion exchange degree; Determine the amount of water required to prepare the metal salt solution: add deionized water dropwise to an equal amount of the zeolite, stir evenly until it becomes a non-Newtonian fluid state, and the amount of water added is the amount of water required to prepare the metal salt solution; The metal salt is mixed with the amount of water to obtain the metal salt solution.

4. The method for preparing a modified zeolite catalyst according to claim 2, characterized in that: The molar ratio of the metal salt to the zeolite is in the range of 0-5, excluding 0.

5. The method for preparing a modified zeolite catalyst according to claim 2, characterized in that: The metal salt includes nitrate and / or acetate.

6. The method for preparing a modified zeolite catalyst according to claim 2, characterized in that: Microwave drying of the non-Newtonian fluid mixture specifically comprises: The non-Newtonian fluid mixture is evenly spread into a crucible, an evaporating dish or a stainless steel beaker, and rapidly heated with a microwave reactor at a power of 100-1000 W for 30 s-30 min.

7. The method for preparing a modified zeolite catalyst according to claim 2, characterized in that: The metal clusters include: Mn 2+ 、Mn2O 2+ 、Mn3O3 2+ 、[AlO2] + , [MnCuO] 2+ 、[Mn2CuO3] 2+ , [FeCoO] 2+ One, two or more of the following.

8. A modified zeolite catalyst, characterized in that The zeolite catalyst is prepared by the preparation method according to any one of claims 1 to 7, and a plurality of metal clusters are evenly distributed in the pores of the zeolite powder in the zeolite catalyst; The metal clusters include metal ions and compatible oxygen atoms; The number of the metal ions is at least 1.

9. An ozone purification method, characterized in that: The ozone purification method uses the zeolite catalyst as claimed in claim 8 to purify ozone; The zeolite catalyst is heated at -10-300°C with a space velocity of 1×10 4 -2×10 6 h -1 The ozone is removed under the conditions of 10. The ozone purification method according to claim 9, characterized in that: The zeolite catalyst forms include but are not limited to powder catalyst, granular catalyst and monolithic catalyst.

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