A zeolite-based bimetallic catalyst for selective generation of active oxygen species and a preparation method and application thereof

Abstract

The present application relates to the field of water treatment catalysis, and discloses a zeolite-based bimetallic catalyst for selective generation of active oxygen species, a preparation method and application thereof, the preparation method comprising the following steps: step 1, treating a zeolite molecular sieve with an inorganic acid, filtering and drying the product to obtain a zeolite molecular cavity material with silanol cavity defects; step 2, mixing the zeolite molecular cavity material with a manganese salt solution, drying, grinding and calcining to obtain a manganese-doped catalyst; step 3, mixing the manganese-doped catalyst with a platinum salt solution, drying, grinding and calcining to obtain the zeolite-based bimetallic catalyst; by adjusting the molar ratio of manganese in the manganese salt and platinum in the platinum salt, the contribution rate of different active oxygen species generated by the zeolite-based bimetallic catalyst is controlled, and specific active oxygen species can be selectively generated under different environmental requirements, which is of great significance for efficient or selective degradation of organic pollutants under different environments.

Description

Technical Field

[0001] This invention relates to the field of water treatment catalysis technology, specifically to a zeolite-based bimetallic catalyst for the selective generation of active oxygen species, its preparation method, and its application. Background Technology

[0002] Advanced oxidation processes (AOPs), such as catalytic ozone oxidation, Fenton and Fenton-like processes, and persulfate catalytic oxidation, have become practical engineering technologies due to their flexibility and efficiency. These technologies generate reactive oxygen species (ROS), such as hydroxyl radicals (·OH) and superoxide radicals (·O). 2- ) and singlet oxygen ( 1 O2 promotes the degradation and mineralization of organic pollutants in water. Among these, free radicals (such as ·OH and ·O) contribute to this degradation. 2- The strong oxidizing properties and electrophilic addition nature of α-Fe make its dominant oxidation reactions widely used in water pollution control processes. 0.9 Mn 0.1 OOH aqueous suspension for the removal of iohexol. Yan et al., Appl. Catal. B-Environ. 2020, 277, 119055”), but the natural organic matter and anions coexisting in water can quench free radicals, thereby inhibiting the selective degradation of target organic pollutants by AOPs.

[0003] On the other hand, non-free radicals (e.g.) 1 Although the O2-dominated oxidation reaction has a low redox potential, its strong selectivity for unsaturated bonds and good resistance to environmental disturbances give it high degradation selectivity. 1 O2 toward nearly 100% selective degradation of organic pollutants. Yao et al., Environ. Sci. Technol. 2022, 56, 8833-8843. Therefore, it is necessary to selectively regulate the generation of specific ROS in AOPs for different environmental treatment needs, providing strong flexibility and applicability for achieving efficient aquatic environment catalysis.

[0004] Catalysts are key to controlling the selective formation of ROS. Zeolites, a type of green aluminosilicate material, possess high specific surface area, ordered pore structure, and excellent physicochemical stability. They inherently exhibit certain catalytic activities or readily combine with intercalated components to form catalytically active components. Certain variable-valence bimetals or their oxides can enhance the decomposition of oxidants (such as ozone and hydrogen peroxide) due to the synergistic effect between metal ions. Achieving selective ROS formation in AOPs to meet different environmental treatment needs is of great significance for solving the problem of efficient or selective degradation of organic pollutants under various environments. Summary of the Invention

[0005] This invention addresses the need for selective generation of ROS species in AOPs by providing a method for preparing a zeolite-based bimetallic catalyst that selectively generates reactive oxygen species. By adjusting the molar ratio of manganese and platinum in the reaction raw materials, the contribution rate of the zeolite-based bimetallic catalyst to the generation of different reactive oxygen species can be controlled, enabling the selective generation of specific ROS under different environmental conditions. This method is of great significance for solving the problem of efficient or selective degradation of organic pollutants under different environments.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a zeolite-based bimetallic catalyst with selective generation of active oxygen species, characterized by comprising the following steps:

[0008] Step 1: The zeolite molecular sieve is treated with inorganic acid, and the product is filtered and dried to obtain zeolite molecular nest material with silanol nest defects.

[0009] Step 2: The zeolite molecular nest material is mixed and reacted with a manganese salt solution, and then dried, ground and calcined to obtain a manganese-doped catalyst.

[0010] Step 3: The manganese-doped catalyst is mixed and reacted with a platinum salt solution, and then dried, ground, and calcined to obtain the zeolite-based bimetallic catalyst.

[0011] By adjusting the molar ratio of manganese in the manganese salt and platinum in the platinum salt, the contribution rate of the zeolite-based bimetallic catalyst to the generation of different active oxygen species can be controlled.

[0012] In this invention, a zeolite-based bimetallic catalyst is prepared by combining acid treatment, manganese impregnation, and platinum impregnation. A schematic diagram of the construction principle is shown below. Figure 1 As shown, acid treatment promotes the dealumination of the zeolite molecular sieve, and the resulting silanol nests are used to immobilize manganese oxides and further serve as anchoring sites for metallic platinum. The insertion of bimetallic manganese-platinum nanoclusters within the zeolite crystals and the increase in the platinum / manganese molar ratio promote the creation of oxygen vacancies and electron-rich, low-valence Pt. 2+ / Pt 4+The formation of active sites accelerates electron transfer and ozone decomposition in platinum oxide during redox processes, increasing the proportion of free radicals generated. When the platinum / manganese molar ratio decreases, platinum in the zeolite-based bimetallic catalyst is predominantly in the high valence state (Pt). 4+ It exists in a form that can oxidize superoxide radicals to form singlet oxygen, thereby increasing the proportion of non-radicals. Therefore, the selective generation of radicals and singlet oxygen can be achieved by adjusting the platinum / manganese ratio (see schematic diagram of catalytic principle). Figure 2 (As shown).

[0013] The zeolite molecular sieve is one or more of type 5A, Y, Beta, CHA, and ZSM; the pore size of the zeolite molecular sieve is... That's all. The dynamic diameter of an Al atom is... The pore size of zeolite molecular sieves should not be less than This facilitates the removal of Al atoms, leading to the formation of silanol nest defects.

[0014] The inorganic acid includes any one of nitric acid, sulfuric acid, and hydrochloric acid;

[0015] In step 1, the mass ratio of the zeolite molecular sieve to the inorganic acid solution is 1:2-50; the concentration of the inorganic acid is 1-13 mol / L, such as 1.5 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L, 12 mol / L, or any value between them. The treatment time is 5-20 hours. Under these conditions, the obtained zeolite molecular nest structure is stable and not prone to collapse, and manganese and platinum atoms can be effectively embedded.

[0016] Preferably, the mass ratio of the zeolite molecular sieve to the inorganic acid solution is 1:10-30; the concentration of the inorganic acid is 5-13 mol / L; and the reaction time is 8-16 h.

[0017] Preferably, the zeolite molecular sieve is type A or type Beta.

[0018] More preferably, when the zeolite molecular sieve is type 5A, the concentration of the inorganic acid is 6-13 mol / L; more preferably, when the zeolite molecular sieve is type Beta, the concentration of the inorganic acid is 1-8 mol / L.

[0019] Preferably, Beta-type zeolite is used as the matrix, and the inorganic acid includes any one of nitric acid, sulfuric acid, and hydrochloric acid. The mass ratio of zeolite molecular sieve to inorganic acid solution is 1:20, the concentration of inorganic acid is 6 mol / L, and the reaction time is 12 h, to ensure that the aluminum component in the zeolite molecular sieve is fully dissolved without affecting its crystal form and pore structure.

[0020] The manganese salt includes one or more of manganese sulfate, manganese nitrate, and manganese acetate.

[0021] The platinum salt includes one or more of tetraammineplatinum nitrate and chloroplatinic acid.

[0022] In step 2, the mass ratio of zeolite molecular nest material to manganese salt solution is 1:3-12, and the concentration of manganese salt solution is 0.05-0.3 mol / L;

[0023] In step 2, the stirring temperature is room temperature, and the stirring time is 20-60 minutes;

[0024] In step 2, the drying temperature is 40-80℃ and the drying time is 2-4 hours;

[0025] In step 2, the material is calcined at a temperature of 450-650℃ for 4-6 hours. Increasing the calcination temperature and extending the calcination time are beneficial for the formation of manganese active sites. At this temperature, manganese oxides decompose stably, manganese metal is less prone to agglomeration, and catalytic efficiency is high. Preferably, the calcination temperature is 550℃ and the calcination time is 5 hours to ensure that manganese is fully inserted into the zeolite molecular nests and that metal agglomeration does not occur.

[0026] The molar ratio of platinum in platinum salts to manganese in manganese salts is 0.1-10:1. Increasing the molar amount of platinum in the catalyst promotes electron migration from manganese to platinum, which is beneficial for electron-rich, low-valence Pt. 2+ / Pt 4+ The formation of active sites promotes the electron transfer ability and ozone decomposition of platinum oxides in the redox process, increases the proportion of free radical generation, and thus enhances catalytic performance; however, excessive platinum will cause metal nanoparticle agglomeration and zeolite channel blockage, reduce its specific surface area, and inhibit its catalytic activity.

[0027] When the molar ratio of platinum to manganese is 0.1-0.2:1, the contribution rate of singlet oxygen is 90%-100%.

[0028] When the molar ratio of platinum to manganese in the zeolite-based bimetallic catalyst is 1-5:1, the free radical contribution rate is 65%-100%; preferably, the molar ratio of platinum to manganese is 1.5-2.5:1, ensuring that the catalyst contains the most low-valence platinum and does not cause zeolite pore blockage or metal nanoparticle agglomeration, with a free radical contribution rate of 85%-100%. More preferably, the molar ratio of platinum to manganese is 2-2.5:1, with a free radical contribution rate of 95%-100%.

[0029] In step 3, the mass ratio of the manganese-doped catalyst to the platinum salt solution is 1:3-12, and the concentration of the platinum salt solution is 0.01-1.5 mol / L;

[0030] In step 3, the stirring temperature is room temperature, and the stirring time is 20-60 minutes;

[0031] In step 3, the drying temperature is 40-80℃ and the drying time is 2-4 hours;

[0032] The material is calcined at a temperature of 250-450℃ for 1-3 hours. Calcination at this temperature ensures sufficient exposure of the platinum active sites and prevents the agglomeration of metal nanoparticles. Preferably, the calcination temperature is 350℃ and the calcination time is 2 hours.

[0033] The reactive oxygen species include hydroxyl radicals, superoxide radicals, or singlet oxygen.

[0034] This invention also provides a zeolite-based bimetallic catalyst prepared according to the described method. Inserting the bimetallic manganese-platinum into the zeolite internal framework facilitates the formation of oxygen vacancies within the catalyst, thereby exposing more low-valence platinum active sites. Simultaneously, by adjusting the platinum-manganese molar ratio in the reactants, the contribution rates of hydroxyl radicals and superoxide radicals in the catalytic ozone oxidation reaction system can be controlled at 95%-100%; alternatively, the manganese-platinum molar ratio can be adjusted to control the singlet oxygen contribution rate at 90%-100%, thus achieving selective generation of reactive oxygen species and adapting to catalytic oxidation in different environments.

[0035] The present invention also provides the application of the zeolite-based bimetallic catalyst in the field of catalytic oxidation.

[0036] When multiple anions and target pollutants coexist in the environment where catalytic oxidation is required, it is preferable that the molar ratio of platinum to manganese in the zeolite-based bimetallic catalyst is 0.1-0.2, and the singlet oxygen contribution rate is 90%-100%, which can selectively remove target pollutants from the environment.

[0037] When the environment requiring catalytic oxidation is a single target pollutant, the molar ratio of platinum to manganese in the zeolite-based bimetallic catalyst is 2-2.5:1, and the free radical contribution rate is 95%-100%, which can efficiently degrade the target pollutant in the environment.

[0038] For complex environments, zeolite-based bimetallic catalysts with different platinum / manganese molar ratios can be used in combination to achieve efficient and selective degradation of target pollutants in the environment.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The zeolite-based bimetallic catalyst of the present invention first constructs silanol nest defects in zeolite, and then embeds manganese and platinum elements into the zeolite structure. The inserted bimetallic manganese-platinum promotes oxygen vacancies and electron-rich, low-valence Pt. 2+ / Pt 4+The formation of active sites accelerates the electron cycle and ozone decomposition of platinum oxides during the redox process, significantly enhancing the catalytic performance of the catalyst.

[0041] (2) The bimetallic catalyst of the present invention can selectively generate specific active oxygen species by adjusting the platinum / manganese molar ratio in the catalyst, adapting to the catalytic oxidation requirements of different environments, and has excellent catalytic performance, providing strong flexibility and applicability for achieving efficient water environment catalysis.

[0042] (3) The catalyst preparation process of the present invention is simple, does not require complex reaction equipment, can be produced on a large scale, and is suitable for industrial application. Attached Figure Description

[0043] Figure 1 This is a schematic diagram illustrating the construction principle of the zeolite-based bimetallic catalyst of the present invention.

[0044] Figure 2 This is a schematic diagram illustrating the mechanism of selective generation of free radicals and singlet oxygen in the catalytic ozone oxidation system of this invention.

[0045] Figure 3 XRD patterns of Beta zeolite molecular sieve, zeolite molecular nest prepared in Example 1, zeolite-based manganese-doped catalyst, zeolite-based bimetallic catalyst and zeolite-based bimetallic catalyst prepared in Example 9.

[0046] Figure 4 FTIR spectra of Beta zeolite molecular sieve, zeolite molecular nest prepared in Example 1, zeolite-based manganese-doped catalyst, zeolite-based bimetallic catalyst and zeolite-based bimetallic catalyst prepared in Example 9.

[0047] Figure 5 The image shows a TEM image of the zeolite-based bimetallic catalyst prepared in Example 9. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should be covered within the protection scope of this invention.

[0049] All raw materials used in the following specific implementation methods were purchased from the market.

[0050] Example 1

[0051] Step 1: 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L). The mixture was stirred at room temperature for 12 hours, then filtered. The mixture was thoroughly washed with deionized water until neutral, and then dried to obtain the zeolite molecular nest material. The crystal form and functional groups of the zeolite molecular nest material were observed using XRD and FTIR, respectively. The results are as follows: Figure 3-4 As shown, the zeolite molecular sieve retained its original BEA crystal form after acid treatment, which led to the formation of silanol functional groups.

[0052] Step 2: Add 1g of zeolite molecular nest powder to 5mL of manganese nitrate solution (0.15mol / L), mix and stir at room temperature for 40min, dry in an oven at 60℃ for 4h, cool naturally to room temperature, place in a muffle furnace, calcine at 550℃ for 5h, and cool naturally to room temperature to obtain zeolite-based manganese-doped catalyst.

[0053] Its crystal form and functional groups were observed using XRD and FTIR, respectively, and the results are as follows: Figure 3-4 As shown, the prepared manganese-doped zeolite molecular nests retain the original BEA crystal form; the peak representing the silanol functional group disappears and a new peak representing the Mn-O bond appears, indicating that manganese nitrate reacts with the silanol functional group to form Si-O-Mn bonds.

[0054] Step 3: Add 0.5g of zeolite-based manganese-doped catalyst to 2.5mL of tetraammine nitrate platinum solution (0.015mol / L), mix and stir at room temperature for 40min, dry in an oven at 60℃ for 4h, cool naturally to room temperature, place in a muffle furnace, calcine at 350℃ for 2h, and cool naturally to room temperature to obtain zeolite-based bimetallic catalyst.

[0055] Its crystal form and functional groups were observed using XRD and FTIR, respectively, and the results are as follows: Figure 3-4 As shown, the prepared zeolite-based bimetallic catalyst retains the original BEA crystal form and exhibits characteristic peaks of platinum, while a new peak representing Mn-O bonds appears, indicating that both manganese and platinum have been successfully inserted into the zeolite crystal.

[0056] Example 2

[0057] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0058] 1 g of zeolite molecular nest material was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0059] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (0.03 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0060] Example 3

[0061] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0062] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0063] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (0.045 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0064] Example 4

[0065] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0066] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0067] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (0.06 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0068] Example 5

[0069] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0070] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0071] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (0.075 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0072] Example 6

[0073] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0074] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0075] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0076] Example 7

[0077] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0078] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0079] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (0.225 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0080] Example 8

[0081] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0082] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0083] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (0.3 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0084] Example 9

[0085] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0086] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0087] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (0.375 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0088] Its crystal form and functional groups were observed using XRD and FTIR, respectively, and the results are as follows: Figure 3-4 As shown, the prepared zeolite-based bimetallic catalyst retains the original BEA crystal form and exhibits characteristic peaks of platinum, while a new peak representing Mn-O bonds appears, indicating that both manganese and platinum have been successfully inserted into the zeolite crystal.

[0089] TEM was used to observe the relative positions of manganese-platinum bimetallic oxide and zeolite molecular nests in the zeolite-based bimetallic catalyst. The results are as follows: Figure 5 As shown, it can be seen that the manganese-platinum bimetal has been uniformly inserted into the zeolite molecular nest crystal (the circle represents the metal nanoparticles).

[0090] Example 10

[0091] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0092] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0093] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (0.45 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0094] Example 11

[0095] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0096] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0097] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (0.6 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0098] Example 12

[0099] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0100] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0101] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (0.75 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0102] Example 13

[0103] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0104] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0105] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (1.05 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0106] Example 14

[0107] 1g of Beta zeolite molecular sieve powder was added to 13.2mL of nitric acid solution (2mol / L), mixed and stirred at room temperature for 12h, filtered, thoroughly washed with deionized water until neutral, and dried to obtain zeolite molecular nest material.

[0108] 1 g of zeolite molecular nest powder was added to 5 mL of manganese nitrate solution (0.15 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 550 °C for 5 h. After naturally cooling to room temperature, manganese-doped zeolite molecular nest catalyst was obtained.

[0109] 0.5 g of zeolite-based manganese-doped catalyst was added to 2.5 mL of tetraammine nitrate platinum solution (1.5 mol / L), mixed and stirred at room temperature for 40 min, dried in an oven at 60 °C for 4 h, and then naturally cooled to room temperature before being placed in a muffle furnace and calcined at 350 °C for 2 h. After naturally cooling to room temperature, the zeolite-based bimetallic catalyst was obtained.

[0110] Pt in Table 1 2+ / Pt 4+ The Pt 4f orbitals were determined using X-ray photoelectron spectroscopy (XPS). The contributions of free radicals and singlet states were calculated using a quenching quantitative method: free radical contribution = (k0–k1) / k0*100% + (k1–k2) / k0*100%, singlet state contribution = (k1–k3) / k0*100%, where k0, k1, k2, and k3 are the pseudo-first-order degradation rate constants (min) of zeolite-based bimetallic catalysts for phenol under the following conditions: no quencher, addition of tert-butanol, addition of p-benzoquinone, and addition of furfuryl alcohol, respectively. -1 The various indicators are shown in Table 1.

[0111] Table 1 Performance indicators of catalysts prepared in Examples 1-14

[0112]

[0113]

[0114] The results show that the zeolite-based bimetallic catalyst prepared in Example 9 has a higher free radical generation ratio (99.8%) compared to the zeolite-based bimetallic catalysts prepared in Examples 1-8 and 10-14. This is closely related to the preparation process used in this invention, especially the molar ratio of platinum and manganese in the reaction raw materials, resulting in more oxygen vacancies and Pt exposed in the final zeolite-based bimetallic catalyst. 2+ / Pt 4+ The active sites accelerate the electron cycle of platinum oxides during the redox process, promoting the decomposition of ozone to generate free radicals.

[0115] Comparing Examples 1-14, the concentrations of the tetraammineplatinum nitrate solution differ, indicating that the concentration of the tetraammineplatinum nitrate solution can affect the concentration of Pt in the zeolite-based bimetallic catalyst. 2+ / Pt 4+ The composition of the catalyst affects the proportion of reactive oxygen species generated. When the concentration of the tetraammineplatinum nitrate solution increases from 0.015 mol / L to 0.375 mol / L, the Pt content in the zeolite-based bimetallic catalyst... 2+ / Pt 4+ The composition increased from 0.11 to 0.83, and the higher proportion of low-valent platinum can decompose ozone into free radicals through electron transfer, thereby increasing the proportion of free radicals;

[0116] When the concentration of the tetraammineplatinum nitrate solution was further increased from 0.375 mol / L to 1.5 mol / L, the Pt in the zeolite-based bimetallic catalyst... 2+ / Pt 4+ The composition decreased from 0.83 to 0.43, presumably due to the agglomeration of metal nanoparticles caused by the excessive insertion of platinum, which simultaneously blocked the zeolite channels, reduced the specific surface area, and thus inhibited the generation of free radicals. Therefore, the zeolite-based bimetallic catalyst prepared at the optimized concentration of platinum tetraamminenitrate solution can selectively generate a larger proportion of free radicals. Conversely, in Example 1, due to the higher proportion of Pt... 4+ It can increase the proportion of non-free radicals by oxidizing superoxide free radicals to form singlet oxygen.

[0117] In practical applications, the manganese / platinum ratio can be adjusted according to the required treatment environment to efficiently generate free radicals or non-free radicals. This is of great significance for solving the problem of efficient or selective degradation of organic pollutants in different environments.

[0118] Application Example 1

[0119] The catalytic performance of the zeolite-based bimetallic catalysts prepared in Examples 1, 2, 8, and 9 in the catalytic oxidation and degradation of phenol in water was compared and tested. The process is as follows:

[0120] Before the reaction, the ozone generator was turned on for 30 minutes to preheat the gas and ensure the oxygen / ozone mixed gas flow rate was 0.4 L / min. 200 mL of phenol solution (20 mg / L) was added to the reactor and mixed thoroughly with magnetic stirring. 20 mg of the catalyst materials prepared in Examples 1, 2, 8, and 9 were added to the solution, and ozone was simultaneously introduced. After reacting for 60 minutes, approximately 2 mL of sample was taken from the reactor. The water sample was treated with a 0.22 μm microporous membrane, and the phenol concentration was determined using high-performance liquid chromatography (HPLC). The removal efficiency is shown in Table 2.

[0121] Application Example 2

[0122] The zeolite-based bimetallic catalysts prepared in Examples 1, 2, 8, and 9 were applied to the catalytic ozone oxidation degradation of Cl-containing anions. - The catalytic effect of phenol in water was tested. The process is as follows:

[0123] Before the reaction, the ozone generator was turned on for 30 minutes to preheat the gas and ensure the oxygen / ozone mixed gas flow rate was 0.4 L / min. 200 mL of a mixed solution of phenol and sodium chloride (initial phenol concentration 20 mg / L, initial sodium chloride concentration 10 mg / L) was added to the reactor and magnetically stirred until homogeneous. 20 mg of the catalyst materials prepared in Examples 1, 2, 8, and 9 were added to the solution, and ozone was simultaneously introduced. After reacting for 60 minutes, approximately 2 mL of sample was taken from the reactor. The water sample was treated with a 0.22 μm microporous membrane, and the phenol concentration was determined using high-performance liquid chromatography (HPLC). The removal efficiency is shown in Table 2.

[0124] Application Example 3

[0125] The catalytic performance of the zeolite-based bimetallic catalysts prepared in Examples 1, 2, 8, and 9 in the catalytic ozone oxidation degradation of anionic phenol in water was tested. The process is as follows:

[0126] Before the reaction, the ozone generator was turned on for 30 minutes to preheat the gas and ensure the oxygen / ozone mixed gas flow rate was 0.4 L / min. 200 mL of a mixed solution of phenol and sodium sulfate (initial concentration of phenol: 20 mg / L, initial concentration of sodium sulfate: 10 mg / L) was added to the reactor and magnetically stirred until homogeneous. 20 mg of the catalyst materials prepared in Examples 1, 2, 8, and 9 were added to the solution, and ozone was simultaneously introduced. After reacting for 60 minutes, approximately 2 mL of sample was taken from the reactor. The water sample was treated with a 0.22 μm microporous membrane, and the phenol concentration was determined using high-performance liquid chromatography (HPLC). The removal efficiency is shown in Table 2.

[0127] Table 2 shows the phenol removal efficiency of the catalysts in Application Examples 1-3.

[0128]

[0129]

[0130] In Application Examples 1-3, the zeolite-based bimetallic catalysts prepared in Examples 8 and 9 exhibited a higher free radical ratio (95%-100%), achieving a phenol removal efficiency of over 98% in water, indicating a high reaction rate for the free radical reaction. However, under conditions where anions, such as chloride or sulfate ions, coexisted, the phenol removal rate decreased by approximately 30%. This is presumably because the presence of coexisting anions in water quenches free radicals, thereby inhibiting their removal performance. This catalyst is more suitable for the removal and degradation of single-target pollutants in water.

[0131] The zeolite-based bimetallic catalysts prepared in Examples 1-2 have a higher proportion of non-radicals (90%-100%). Since the redox potential of non-radicals (such as singlet oxygen) is lower than that of free radicals (such as hydroxyl radicals and superoxide radicals), the removal efficiencies of the zeolite-based bimetallic catalysts prepared in Examples 1-2 for phenol removal from water (82.3% and 84.1%, respectively) are lower than those prepared in Examples 8 and 9. However, the non-radical reaction is not affected by coexisting anions in water. When chloride or sulfate ions are present, the removal efficiency of the zeolite-based bimetallic catalysts prepared in Examples 1 and 2 for phenol removal from water remains essentially unchanged, indicating that the non-radical reaction has good selectivity. Therefore, the catalysts of Examples 1-2 are more suitable for environments where multiple anions and target pollutants coexist in water.

[0132] Therefore, this invention provides a method for selectively generating active oxygen species in zeolite-based bimetallic catalysts. This method can selectively generate specific active oxygen species in the catalytic ozone oxidation reaction according to the degradation requirements of organic pollutants under different environments. For more complex environments, catalysts with high free radical contribution rates can be combined with catalysts with high non-free radical contribution rates to achieve efficient and selective degradation of organic pollutants in water, which has good application prospects.

Claims

1. A method for preparing a zeolite-based bimetallic catalyst with selective generation of active oxygen species, characterized in that, Including the following steps: Step 1: The zeolite molecular sieve is treated with an inorganic acid solution, and the product is filtered and dried to obtain a zeolite molecular nest material with silanol nest defects; the pore size of the zeolite molecular sieve is greater than 5 angstroms. Step 2: The zeolite molecular nest material is mixed and reacted with a manganese salt solution, and then dried, ground and calcined to obtain a manganese-doped catalyst. Step 3: The manganese-doped catalyst is mixed and reacted with a platinum salt solution, and then dried, ground, and calcined to obtain the zeolite-based bimetallic catalyst. The contribution rate of the zeolite-based bimetallic catalyst to the generation of different active oxygen species is controlled by adjusting the molar ratio of manganese in the manganese salt to platinum in the platinum salt; the molar ratio of platinum in the platinum salt to manganese in the manganese salt is 0.1-10:

1. When the molar ratio of platinum to manganese in the zeolite-based bimetallic catalyst is 0.1-0.2:1, the singlet oxygen contribution rate of the zeolite-based bimetallic catalyst is 90%-100%. When the molar ratio of platinum to manganese in the zeolite-based bimetallic catalyst is 1-5:1, the free radical contribution rate of the zeolite-based bimetallic catalyst is 65%-100%.

2. The method for preparing the zeolite-based bimetallic catalyst with selective generation of active oxygen species according to claim 1, characterized in that, The zeolite molecular sieve is one or more of the following types: 5A, Y, Beta, and ZSM.

3. The method for preparing the zeolite-based bimetallic catalyst with selective generation of active oxygen species according to claim 1, characterized in that, Inorganic acids include any one of nitric acid, sulfuric acid, and hydrochloric acid; And / or, in step 1, the mass ratio of the zeolite molecular sieve to the inorganic acid solution is 1:2-50; the concentration of the inorganic acid solution is 1-13 mol / L; and the treatment time is 5-20 h.

4. The method for preparing the zeolite-based bimetallic catalyst with selective generation of active oxygen species according to claim 1, characterized in that, The zeolite molecular sieve is of type 5A or type Beta.

5. The method for preparing the zeolite-based bimetallic catalyst with selective generation of active oxygen species according to claim 1, characterized in that, The manganese salt includes one or more of manganese sulfate, manganese nitrate, and manganese acetate; and / or, the platinum salt includes one or more of tetraammineplatinum nitrate and chloroplatinic acid.

6. The method for preparing the zeolite-based bimetallic catalyst with selective generation of active oxygen species according to claim 1, characterized in that, In step 2, the mass ratio of zeolite molecular nest material to manganese salt solution is 1:3-12, and the concentration of manganese salt solution is 0.05-0.3 mol / L; And / or, in step 2, after mixing, stir at room temperature for 20-60 minutes; And / or, in step 2, the drying temperature is 40-80℃ and the drying time is 2-4h; And / or, in step 2, the calcination temperature is 450-650℃ and the calcination time is 4-6h.

7. The method for preparing the zeolite-based bimetallic catalyst with selective generation of active oxygen species according to claim 1, characterized in that, In step 3, the mass ratio of the manganese-doped catalyst to the platinum salt solution is 1:3-12, and the concentration of the platinum salt solution is 0.01-1.5 mol / L; And / or, after mixing, stir at room temperature for 20-60 minutes; And / or, the drying temperature is 40-80℃, and the drying time is 2-4 hours; And / or, in step 3, the calcination temperature is 250-450℃ and the calcination time is 1-3h.

8. A zeolite-based bimetallic catalyst prepared by the preparation method according to any one of claims 1-7.

9. The application of the zeolite-based bimetallic catalyst according to claim 8 in the field of catalytic oxidation.

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