A catalyst for catalytic oxidation of toluene and its preparation method

Abstract

The present invention relates to the technical field of catalysts, and particularly to a catalyst for catalytic oxidation of toluene and a preparation method thereof. The preparation method includes the following steps: Step 1, dissolving 2-methylimidazole and a sulfur source in an organic solvent to obtain Solution 1; dissolving a zinc source, a nickel source and a quaternary ammonium salt in an organic solvent to obtain Solution 2; mixing the Solution 1 and the Solution 2 and stirring to obtain a mixed solution; Step 2, carrying out in-situ solvothermal synthesis on the mixed solution, and then centrifuging the obtained precipitate, washing, drying and grinding to obtain a precursor powder; Step 3, pyrolyzing the precursor powder under an inert atmosphere to obtain the catalyst for catalytic oxidation of toluene. The catalyst prepared by the present invention realizes effective degradation of toluene under normal temperature conditions without external energy (ultraviolet light irradiation, high temperature, high voltage discharge, ozone assistance) input, reduces the energy consumption in the treatment process, reduces the treatment cost, improves the reaction safety, and promotes the development of green catalysis of VOCs.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly to a catalyst for catalytic oxidation of toluene and a preparation method thereof. Background Art

[0002] Volatile organic compounds (VOCs) are an important type of air pollutant, mainly originating from processes such as transportation, fuel combustion, and industrial production emissions. VOCs participate in the formation processes of secondary organic aerosols, O3, NOx, haze, and other air pollutants in the environment, causing damage to the ecological environment. In addition, VOCs directly endanger human health. Exposure to high concentrations of VOCs can cause acute symptoms such as headache and vomiting, and may also lead to cardiovascular diseases, nervous system damage, organ failure, etc. Therefore, the control and treatment of VOCs are of crucial importance. Currently, VOCs treatment technologies mainly include adsorption, absorption, biodegradation, combustion, catalytic oxidation, photocatalysis, etc. Among them, the catalytic oxidation method can efficiently degrade VOCs at relatively low temperatures. However, traditional catalytic oxidation technologies require high-temperature and high-pressure conditions to achieve the catalytic reaction, not only with high energy consumption during the treatment process, but also having problems such as catalyst sintering and deactivation, and poor safety. The room-temperature catalytic oxidation technology can effectively avoid the heat energy consumption at high temperatures, and at the same time helps to improve the use stability of the catalyst and reduce the pollutant treatment cost, which is a current popular research direction.

[0003] Catalysts are the key to catalytic oxidation technology. Atomic-level active site catalysts show higher catalytic activity and stability in catalytic reactions due to their 100% atomic utilization rate, strong metal-support interaction, and unsaturated coordination environment. Toluene, as a typical VOC pollutant, is difficult to catalytically oxidize due to its stable six-membered ring structure. The reaction temperature of existing catalysts is still relatively high, and the related catalyst research mainly focuses on noble metal catalysts, with relatively high preparation costs. Therefore, in order to efficiently treat toluene and reduce energy and resource waste, it is urgent to construct a transition metal catalyst with high catalytic activity, good stability, simple preparation, and low price that can efficiently and thoroughly degrade toluene under normal temperature and pressure conditions. Summary of the Invention

[0004] Based on the above, the present invention provides a catalyst for catalytic oxidation of toluene (S-doped atomic-level active site ZnNi / SNC catalyst, hereinafter referred to as ZnNi / SNC catalyst) and a preparation method thereof. By doping and modifying with S atoms, the room-temperature catalytic activity of the catalyst for toluene is improved. The catalyst of the present invention can effectively degrade toluene under room-temperature conditions without the input of external energy (ultraviolet light irradiation, high temperature, high-voltage discharge, ozone assistance), solving the problems of poor catalyst activity, high catalytic reaction temperature, low economic efficiency, and poor safety existing in the prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is a catalyst for catalytic oxidation of toluene, which is an S-doped atomic active site ZnNi / SNC catalyst; the ZnNi / SNC catalyst uses Zn and Ni bimetals as active components and S as a doping component; the atomic ratio of Zn:Ni:S in the ZnNi / SNC catalyst is (20-50):1:(5-20).

[0007] Another technical solution of the present invention is a preparation method of the above-mentioned catalyst for catalytic oxidation of toluene, which includes the following steps:

[0008] Step 1: Dissolve 2-methylimidazole and a sulfur source in an organic solvent to obtain solution 1; dissolve a zinc source, a nickel source and a quaternary ammonium salt in an organic solvent to obtain solution 2; mix the solution 1 and the solution 2 and stir to obtain a mixed solution;

[0009] Step 2: Carry out in-situ solvothermal synthesis on the mixed solution, and then centrifuge the obtained precipitate, wash, dry and grind it to obtain a precursor powder;

[0010] Step 3: Pyrolyze the precursor powder under an inert atmosphere to obtain the catalyst for catalytic oxidation of toluene.

[0011] In step 1, the present invention uses Zn and Ni metal precursors and an organic ligand (2-methylimidazole) to form a zeolitic imidazolate framework material through a coordination reaction in a solvent, and this process is manifested as a clear solution turning into a suspension. The purpose of separately preparing the metal ion solution (i.e., solution 2) is to uniformly mix the metal precursors and then add them to an organic solvent. If all raw materials are added to the organic solvent together (i.e., the organic ligand 2-methylimidazole, the sulfur source, the zinc source, the nickel source, and the quaternary ammonium salt are added to the organic solvent together), it will cause certain differences in the bulk structure, microscopic morphology and surface characteristics of the material, affecting the catalytic performance. That is, the addition sequence and timing of the raw materials will affect the synthesis of the material and thus the catalytic performance of the finally prepared catalyst.

[0012] Further, in step 1, the sulfur source is one or more of thiourea, 2,5-thiophenedicarboxylic acid, and ammonium thiocyanate.

[0013] Further, in step 1, the zinc source is one or more of zinc nitrate hexahydrate, zinc sulfate, and zinc chloride.

[0014] Further, in step 1, the nickel source is one or more of nickel nitrate hexahydrate, nickel sulfate hexahydrate, nickel chloride hexahydrate, and nickel acetate tetrahydrate; the quaternary ammonium salt is cetyltrimethylammonium bromide.

[0015] Cetyltrimethylammonium bromide acts as a template agent in the present invention; the growth rate of the material can be adjusted by regulating the addition amount of cetyltrimethylammonium bromide, thereby controlling the crystal morphology, specific surface area and particle size. The effects of different types and concentrations of surfactants on the synthesis of ZIF materials are different.

[0016] Further, in step 1, the organic solvents in the preparation processes of solution 1 and solution 2 are both methanol.

[0017] The type of organic solvent will affect the crystal form, morphology, porosity, reaction rate and product purity of the material. Replacing methanol with commonly used reagents in the art such as water, ethanol, etc. will affect the catalytic performance of the finally prepared catalyst. Therefore, the present invention defines the organic solvent as methanol.

[0018] Further, in step 1, the molar ratio of 2-methylimidazole to the sulfur source, zinc source, and nickel source is (500 - 1250):(5 - 20):(20 - 50):1.

[0019] Further, in step 1, the concentration of 2-methylimidazole in the solution 1 is 0.45 g / mL; in the solution 2, the concentration of the zinc source is 0.03 g / mL.

[0020] Further, in step 1, the stirring rate is 200 r / min and the time is 0.5 - 1.5 h.

[0021] The purpose of stirring is to improve the uniformity of the reaction system, which is beneficial to the subsequent solvothermal reaction.

[0022] Further, in step 2, the temperature of the in-situ solvothermal synthesis is 100 - 180 °C and the time is 2 - 6 h.

[0023] Further, in step 3, the pyrolysis is specifically: heating to 800 - 1000 °C at a heating rate of 5 - 15 °C / min and holding for 1 - 4 h.

[0024] Under the above pyrolysis conditions, the sulfur source is carbonized during the high-temperature pyrolysis process, and S atoms are doped into the carbon framework, forming C-S-C coordination with C elements in the carbon framework or forming metal-S coordination configuration with metal atoms, which helps to regulate the active sites of metal atoms.

[0025] The third technical solution of the present invention is the application of the above-mentioned catalyst for catalytic oxidation of toluene in the degradation of volatile organic compounds, especially toluene.

[0026] The present invention discloses the following technical effects:

[0027] (1) The catalyst prepared by the present invention realizes the effective degradation of toluene under normal temperature conditions without the input of external energy (ultraviolet light irradiation, high temperature, high voltage discharge, ozone assistance), reduces the energy consumption in the treatment process, lowers the treatment cost, improves the reaction safety, and promotes the development of green catalysis for VOCs.

[0028] (2) The present invention uses S element doping to change the surface microstructure of the catalyst, forming a hierarchical porous structure, and at the same time regulating the neighboring coordination atoms of Ni active sites, improving the electron transfer ability of metal active sites, enhancing the adsorption and activation of toluene and O2 molecules by the catalyst, and breaking the catalytic kinetic limit through an efficient adsorption-catalysis mechanism to achieve the room-temperature catalytic oxidation of toluene.

[0029] (3) Currently, the atomic-level active site catalysts applied to VOCs degradation mainly focus on noble metal catalysts. Based on excellent catalytic effects, the transition metal catalyst modified by S doping in the present invention improves the utilization rate of transition metal atoms, can effectively replace noble metal catalysts, reduces the catalyst cost, and has certain economic feasibility in practical applications. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 It is the X-ray diffraction spectrum of the ZnNi / SNC catalyst in Example 1;

[0032] Figure 2 It is the aberration-corrected high-angle annular dark-field scanning transmission electron microscope image of the ZnNi / SNC catalyst in Example 1 at a 2nm scale;

[0033] Figure 3 It is the scanning electron microscope images of the ZnNi / NC catalyst in Comparative Example 1 (a) and the ZnNi / SNC catalyst in Example 1 (b) at a 100nm scale;

[0034] Figure 4 It is the X-ray photoelectron spectrum of S 2p of the ZnNi / SNC catalyst in Example 1. Detailed Embodiments

[0035] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0036] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0037] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0038] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0039] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0040] The "room temperature" described in the present invention, unless otherwise specified, all represents 15 - 35 °C.

[0041] The raw materials used in the examples of the present invention, unless otherwise specified, are all obtained through commercial channels.

[0042] Example 1

[0043] Step (1): Dissolve 9 g of 2-methylimidazole and 76.2 mg of thiourea in 20 mL of methanol solution to obtain Solution 1. Dissolve 1.2 g of zinc nitrate hexahydrate, 28.9 mg of nickel nitrate hexahydrate, and 20 mg of cetyltrimethylammonium bromide in 40 mL of methanol solution, stir evenly to obtain Solution 2. Then, mix Solution 1 and 2 and stir at room temperature for 0.5 h to obtain a turbid mixed solution.

[0044] Step (2): Transfer the mixed solution obtained in step (1) into a reaction kettle equipped with a polytetrafluoroethylene liner, and place the reaction kettle in an oven at 120 °C for reaction for 4 h. After cooling to room temperature, centrifuge the precipitate and wash it 3 times with methanol solution, and then dry it in an oven at 70 °C. After the sample is dried, grind it evenly to obtain the precursor powder.

[0045] Step (3): Place the precursor powder in a tube furnace, heat it to 950 °C at a heating rate of 5 °C / min in an N2 atmosphere for pyrolysis for 2 h, and after it naturally cools to room temperature, obtain the ZnNi / SNC catalyst, denoted as A.

[0046] Example 2

[0047] Step (1): Dissolve 9 g of 2-methylimidazole and 206.6 mg of 2,5-thiophenedicarboxylic acid in 20 mL of methanol solution to obtain solution 1. Dissolve 1.2 g of zinc nitrate hexahydrate, 23.12 mg of nickel nitrate hexahydrate and 10 mg of cetyltrimethylammonium bromide in 40 mL of methanol solution, stir evenly to obtain solution 2. Then, mix solution 1 and 2 and stir at room temperature for 1 h to obtain a turbid mixed solution.

[0048] Step (2): Transfer the mixed solution obtained in step (1) into a reaction kettle equipped with a polytetrafluoroethylene liner, and place the reaction kettle in an oven at 120 °C for reaction for 4 h. After cooling to room temperature, centrifuge the precipitate and wash it 3 times with methanol solution, and then dry it in an oven at 70 °C. After the sample is dried, grind it evenly to obtain the precursor powder.

[0049] Step (3): Place the precursor powder in a tube furnace, heat it to 900 °C at a heating rate of 10 °C / min in an N2 atmosphere for pyrolysis for 1 h, and after it naturally cools to room temperature, obtain the ZnNi / SNC catalyst, denoted as B.

[0050] Example 3

[0051] Step (1): Dissolve 9 g of 2-methylimidazole and 74.8 mg of ammonium thiocyanate in 20 mL of methanol solution to obtain solution 1. Dissolve 1.2 g of zinc nitrate hexahydrate, 38.5 mg of nickel nitrate hexahydrate and 20 mg of cetyltrimethylammonium bromide in 40 mL of methanol solution, stir evenly to obtain solution 2. Then, mix solution 1 and 2 and stir at room temperature for 1.5 h to obtain a turbid mixed solution.

[0052] Step (2): Transfer the mixed solution obtained in step (1) into a reaction kettle equipped with a polytetrafluoroethylene liner, and place the reaction kettle in an oven at 160 °C for reaction for 5 h. After cooling to room temperature, centrifuge the precipitate and wash it 3 times with methanol solution, and then dry it in an oven at 90 °C. After the sample is dried, grind it evenly to obtain the precursor powder.

[0053] Step (3): Place the precursor powder in a tubular furnace, heat it up to 1000 °C at a heating rate of 15 °C / min in an N2 atmosphere for pyrolysis for 2 h. After it naturally cools down to room temperature, the ZnNi / SNC catalyst is obtained, denoted as C.

[0054] Example 4

[0055] Step (1): Dissolve 9 g of 2-methylimidazole and 304.5 mg of thiourea in 20 mL of methanol solution to obtain Solution 1. Dissolve 1.2 g of zinc nitrate hexahydrate, 57.8 mg of nickel nitrate hexahydrate and 10 mg of cetyltrimethylammonium bromide in 40 mL of methanol solution, stir evenly to obtain Solution 2. Then, mix Solution 1 and 2 and stir at room temperature for 1 h to obtain a turbid mixed solution.

[0056] Step (2): Transfer the mixed solution obtained in Step (1) to a reaction kettle equipped with a polytetrafluoroethylene inner liner, place the reaction kettle in an oven at 100 °C and react for 6 h. After cooling to room temperature, centrifuge the precipitate and wash it 3 times with methanol solution, and then dry it in an oven at 80 °C. After the sample is dried, grind it evenly to obtain the precursor powder.

[0057] Step (3): Place the precursor powder in a tubular furnace, heat it up to 800 °C at a heating rate of 10 °C / min in an N2 atmosphere for pyrolysis for 4 h. After it naturally cools down to room temperature, the ZnNi / SNC catalyst is obtained, denoted as D.

[0058] Example 5

[0059] Step (1): Dissolve 9 g of 2-methylimidazole and 148.4 mg of thiourea in 20 mL of methanol solution to obtain Solution 1. Dissolve 1.2 g of zinc nitrate hexahydrate, 38.5 mg of nickel nitrate hexahydrate and 20 mg of cetyltrimethylammonium bromide in 40 mL of methanol solution, stir evenly to obtain Solution 2. Then, mix Solution 1 and 2 and stir at room temperature for 0.5 h to obtain a turbid mixed solution.

[0060] Step (2): Transfer the mixed solution obtained in Step (1) to a reaction kettle equipped with a polytetrafluoroethylene inner liner, place the reaction kettle in an oven at 180 °C and react for 2 h. After cooling to room temperature, centrifuge the precipitate and wash it 3 times with methanol solution, and then dry it in an oven at 60 °C. After the sample is dried, grind it evenly to obtain the precursor powder.

[0061] Step (3): Place the precursor powder in a tubular furnace, heat it up to 920 °C at a heating rate of 8 °C / min in an N2 atmosphere for pyrolysis for 3 h. After it naturally cools down to room temperature, the ZnNi / SNC catalyst is obtained, denoted as E.

[0062] Comparative Example 1

[0063] It is only different from Example 1 in that no sulfur source (thiourea) is added during the preparation process. The specific preparation steps are as follows:

[0064] Step (1): Dissolve 9 g of 2-methylimidazole in 20 mL of methanol solution to obtain Solution 1. Dissolve 1.2 g of zinc nitrate hexahydrate, 28.9 mg of nickel nitrate hexahydrate, and 20 mg of cetyltrimethylammonium bromide in 40 mL of methanol solution, stir evenly to obtain Solution 2. Then, mix Solution 1 and 2 and stir at room temperature for 0.5 h to obtain a turbid mixed solution.

[0065] Step (2): Transfer the mixed solution obtained in Step (1) to a reaction kettle equipped with a polytetrafluoroethylene inner liner, and place the reaction kettle in an oven at 120 °C for reaction for 4 h. After cooling to room temperature, centrifuge the precipitate and wash it 3 times with methanol solution, and then dry it in an oven at 70 °C. After the sample is dried, grind it evenly to obtain the precursor powder.

[0066] Step (3): Place the precursor powder in a tubular furnace, heat it to 950 °C at a heating rate of 5 °C / min under a N2 atmosphere for pyrolysis for 2 h, and after it naturally cools to room temperature, obtain the ZnNi / NC catalyst, denoted as F.

[0067] Comparative Example 2

[0068] It is only different from Example 1 in that no metal Ni precursor (nickel nitrate hexahydrate) is added during the preparation process. The specific preparation steps are as follows:

[0069] Step (1): Dissolve 9 g of 2-methylimidazole and 76.2 mg of thiourea in 20 mL of methanol solution to obtain Solution 1. Dissolve 1.2 g of zinc nitrate hexahydrate and 20 mg of cetyltrimethylammonium bromide in 40 mL of methanol solution, stir evenly to obtain Solution 2. Then, mix Solution 1 and 2 and stir at room temperature for 0.5 h to obtain a turbid mixed solution.

[0070] Step (2): Transfer the mixed solution obtained in Step (1) to a reaction kettle equipped with a polytetrafluoroethylene inner liner, and place the reaction kettle in an oven at 120 °C for reaction for 4 h. After cooling to room temperature, centrifuge the precipitate and wash it 3 times with methanol solution, and then dry it in an oven at 70 °C. After the sample is dried, grind it evenly to obtain the precursor powder.

[0071] Step (3): Place the precursor powder in a tubular furnace, heat it to 950 °C at a heating rate of 5 °C / min under a N2 atmosphere for pyrolysis for 2 h, and after it naturally cools to room temperature, obtain the Zn / SNC catalyst, denoted as G.

[0072] Evaluate the performance of the catalysts prepared in Examples 1-5 and Comparative Examples 1-2 as follows:

[0073] The catalysts of Examples 1-5 and Comparative Examples 1-2 were respectively loaded into a fixed-bed reactor with an inner diameter of 8 mm, and the initial concentration of toluene was controlled to be 1000 mg / m 3 , the reaction mass space velocity was 70000 mL / (g·h), the reaction temperature was 25 °C, the relative humidity was 10%, and the oxidant was air. Under these catalyst evaluation conditions, the toluene concentration in the tail gas was monitored by a gas chromatography FID detector, and the toluene removal rate was calculated. The results are shown in Table 1.

[0074] The calculation formula of the toluene removal rate is as follows:

[0075]

[0076] Where: X is the toluene removal rate, %; C in and C out represent the inlet and outlet concentrations of toluene, respectively, in mg / m 3 .

[0077] Table 1

[0078]

[0079]

[0080] It can be seen from Table 1 that the ZnNi / SNC catalysts (S-doped atomic active site ZnNi / SNC catalysts) prepared in Examples 1-5 have good toluene removal effects. Among them, the ZnNi / SNC catalyst prepared in Example 1 has a higher toluene removal rate compared with other catalysts, which can reach more than 99%. The X-ray diffraction spectrum of this catalyst is as Figure 1 , and it can be seen from Figure 1 that there are only two broad peaks attributed to the (002) and (101) crystal planes of graphite carbon in this catalyst, and no diffraction peaks related to Zn and Ni species appear, indicating that Zn and Ni atoms in the catalyst are uniformly dispersed. The aberration-corrected high-angle annular dark-field scanning transmission electron microscopy image is as Figure 2 , Figure 2 which further intuitively proves that the metal elements (Zn and Ni) in the catalyst are atomically distributed.

[0081] Compared with Example 1, the performance of the catalyst without S element doping in Comparative Example 1 is significantly reduced, which is because S atom doping can change the surface microstructure of the catalyst, Figure 3Scanning electron microscope images of the ZnNi / NC catalyst (a) in Comparative Example 1 and the ZnNi / SNC catalyst (b) in Example 1 at a scale of 100 nm. It can be clearly seen from the figure that after S element doping, the edges of the catalyst prisms are not obvious, the surface is granular and uneven, presenting a rough and porous irregular spherical structure, which affects the pore structure and surface defects of the catalyst. The formed hierarchical porous structure is beneficial to the adsorption and enrichment of reactants by the catalyst, and at the same time is conducive to exposing abundant active sites and enhancing the accessibility of reactants and key intermediates. In addition, through the peak fitting of the X-ray photoelectron spectroscopy of S 2p of the ZnNi / SNC catalyst, the results are as Figure 4 shown, indicating that S atoms can be doped into the carbon matrix to form C-S-C bonds to produce long-range interactions, and at the same time directly form Zn / Ni-S bonds with the active metal centers, successfully regulating the neighboring coordination atoms of the Zn and Ni active sites, promoting the electron transfer of the metal centers, improving the adsorption and activation of reactants and O2 molecules, effectively enhancing the catalytic activity and stability of the catalyst, breaking the kinetic limit of toluene catalytic oxidation at room temperature, and promoting the ring-opening degradation of toluene. Compared with Example 1, in Comparative Example 2, Ni was not added and only Zn was contained as a metal, and its catalytic effect was poor, indicating that the addition of metal Ni can effectively improve the catalytic activity of the catalyst, and there may be a synergistic effect of multi-metal active centers of Zn and Ni, which is beneficial to the catalytic oxidation of toluene at room temperature.

[0082] In the present invention, the adsorption-catalytic performance of the catalyst for toluene is improved by S element doping. The incorporation of S atoms can change the surface microtopography of the catalyst, which helps to form a rich porous structure. In addition, the doping of S atoms with a smaller electronegativity can replace the N atoms with a stronger electronegativity coordinated with the metal. S atoms can directly form metal-S bonds with the active metal centers, promoting the electron transfer of the active metal center Ni. At the same time, through the long-range interaction of C-S-C bonds in the carbon matrix, the adsorption and activation performance of the catalyst for reactants and O2 molecules is synergistically improved, effectively enhancing the catalytic activity and stability of the catalyst, breaking the kinetic limit of toluene catalytic oxidation at room temperature, and promoting the ring-opening degradation of toluene.

[0083] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A catalyst for catalytic oxidation of toluene, characterized in that, It is a ZnNi / SNC catalyst with S-doped atomic active sites; the ZnNi / SNC catalyst uses Zn and Ni bimetals as active components and S as a doping component; the atomic ratio of Zn:Ni:S in the ZnNi / SNC catalyst is (20-50):1:(5-20); The preparation method of the catalyst for catalytic oxidation of toluene includes the following steps: Step 1, dissolve 2-methylimidazole and a sulfur source in an organic solvent to obtain Solution 1; dissolve a zinc source, a nickel source and a quaternary ammonium salt in an organic solvent to obtain Solution 2; mix the Solution 1 and the Solution 2 and stir to obtain a mixed solution; Step 2, perform in-situ solvothermal synthesis on the mixed solution, and then wash, dry and grind the obtained precipitate by centrifugation to obtain a precursor powder; Step 3, pyrolyze the precursor powder under an inert atmosphere to obtain the catalyst for catalytic oxidation of toluene; In Step 1, the sulfur source is one or more of thiourea, 2,5-thiophenedicarboxylic acid and ammonium thiocyanate, the quaternary ammonium salt is cetyltrimethylammonium bromide, and the organic solvent in the preparation processes of the Solution 1 and the Solution 2 is methanol; In Step 2, the temperature of the in-situ solvothermal synthesis is 100-180 °C and the time is 2-6 h; In Step 3, the pyrolysis is specifically: heating at a heating rate of 5-15 °C / min to 800-1000 °C and holding for 1-4 h.

2. The catalyst for catalytic oxidation of toluene according to claim 1, characterized in that, In Step 1, the zinc source is one or more of zinc nitrate hexahydrate, zinc sulfate, zinc chloride.

3. The catalyst for catalytic oxidation of toluene according to claim 1, characterized in that, In Step 1, the nickel source is one or more of nickel nitrate hexahydrate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate.

4. The catalyst for catalytic oxidation of toluene according to claim 1, characterized in that, In Step 1, the molar ratio of 2-methylimidazole to the sulfur source, the zinc source and the nickel source is (500-1250):(5-20):(20-50):1; the concentration of the quaternary ammonium salt in the Solution 2 is 0.25-0.5 mg / mL.

5. Application of the catalyst for catalytic oxidation of toluene according to claim 1 in degradation of volatile organic compounds.

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