VOCs catalyst as well as preparation method and application thereof

Abstract

The invention provides a VOCs catalyst as well as a preparation method and application thereof, and belongs to the field of atmosphere prevention and control. The invention provides a VOCs (Volatile Organic Compounds) catalyst. The VOCs catalyst comprises a modified ZSM-5 zeolite molecular sieve and active metal and / or oxide of the active metal loaded on the modified ZSM-5 zeolite molecular sieve, the preparation method of the modified ZSM-5 zeolite molecular sieve comprises the following steps: mixing a ZSM-5 zeolite molecular sieve and an organic alkali solution, and carrying out a hydrothermal reaction to obtain an organic alkali-loaded ZSM-5 zeolite molecular sieve; and roasting the ZSM-5 zeolite molecular sieve loaded with the organic alkali, and removing the organic alkali to obtain the modified ZSM-5 zeolite molecular sieve, the organic alkali solution is a tetrapropylammonium hydroxide solution.

Description

Technical Field

[0001] The present invention relates to the field of air pollution control, and in particular to a VOCs catalyst and a preparation method and application thereof. Background Art

[0002] Volatile organic compounds (VOCs) refer to a series of organic compounds with a boiling point of 50 to 260°C at room temperature, and are important air pollutants. VOCs not only participate in the formation of photochemical smog, but can also cause respiratory and skin irritation, and even induce cancer in the body, posing a great threat to the environment and human health. Therefore, VOCs treatment technology has received increasing attention.

[0003] Applied VOCs treatment technologies include absorption, adsorption, condensation, membrane separation, biochemical, low-temperature plasma, photocatalytic oxidation, direct combustion and catalytic combustion, etc. Among them, catalytic oxidation to eliminate VOCs is the most promising technology, and toxic VOCs can be oxidized into CO2, water and other relatively less harmful substances at relatively low temperatures.

[0004] ZSM-5 zeolite molecular sieve is often used as a carrier for VOCs catalysts because of its high specific surface area, rich pore structure, strong hydrophobicity, more acid sites, complex channels and excellent thermal stability. However, ZMS-5 zeolite molecular sieve is prone to a series of problems such as deposition or pore blockage, acid site deactivation, etc. due to the production of by-products. Therefore, it is necessary to further improve the performance of ZSM-5 zeolite molecular sieve to improve the stability and anti-poisoning performance of the catalyst. Summary of the invention

[0005] The present invention provides a VOCs catalyst and a preparation method and application thereof. The active metal in the VOCs catalyst of the present invention has high dispersibility and excellent stability and anti-poisoning properties.

[0006] The present invention provides a VOCs catalyst, comprising a modified ZSM-5 zeolite molecular sieve and an active metal and / or an active metal oxide loaded on the modified ZSM-5 zeolite molecular sieve;

[0007] The preparation method of the modified ZSM-5 zeolite molecular sieve comprises the following steps:

[0008] The ZSM-5 zeolite molecular sieve and the organic base solution are mixed and then subjected to a hydrothermal reaction to obtain a ZSM-5 zeolite molecular sieve loaded with an organic base;

[0009] The organic base-loaded ZSM-5 zeolite molecular sieve is calcined to remove the organic base, thereby obtaining the modified ZSM-5 zeolite molecular sieve;

[0010] The organic alkali solution is tetrapropylammonium hydroxide solution.

[0011] Preferably, the silicon-aluminum ratio of the ZSM-5 zeolite molecular sieve is 25-85.

[0012] Preferably, the ZSM-5 zeolite molecular sieve includes H-ZSM-5 zeolite molecular sieve and / or Na-ZSM-5 zeolite molecular sieve.

[0013] Preferably, the ratio of the mass of the ZSM-5 zeolite molecular sieve to the amount of the organic base in the organic base solution is 5 g: 0.4-1 mol.

[0014] Preferably, the temperature of the hydrothermal reaction is 170° C. and the time is 72 h.

[0015] Preferably, the calcination temperature is 550° C. and the calcination time is 6 hours.

[0016] Preferably, the active metal comprises platinum and / or palladium.

[0017] Preferably, the mass ratio of the total active metal elements in the active metal and / or active metal oxide to the modified ZSM-5 zeolite molecular sieve is 1:0.005-0.01.

[0018] The present invention also provides a method for preparing the VOCs catalyst described in the above technical solution, comprising the following steps:

[0019] The modified ZSM-5 zeolite molecular sieve, water and an acid solution or a salt solution corresponding to an active metal element are mixed, and then the water in the obtained mixture is removed and then calcined to obtain the VOCs catalyst.

[0020] The present invention also provides the use of the VOCs catalyst described in the above technical solution or the VOCs catalyst prepared by the preparation method described in the above technical solution in treating tail gas containing VOCs.

[0021] The present invention utilizes tetrapropylammonium hydroxide to perform hydrothermal reaction and calcine on ZSM-5 zeolite molecular sieve, thereby manufacturing abundant defects on the surface of ZSM-5 zeolite molecular sieve (forming a porous structure, i.e., the confinement effect of the catalyst), providing more anchoring points for active metals, so that the active metals can be evenly dispersed in the ZSM-5 zeolite molecular sieve containing defects, avoiding the agglomeration of the active metals, and thus improving the surface area and reaction activity of the catalyst.

[0022] Compared with the traditional method, the ZSM-5 zeolite molecular sieve prepared by the present invention also makes the VOCs catalyst have excellent resistance to carbon deposition and anti-poisoning performance: by introducing the confinement effect, a tiny space can be formed on the catalyst surface to limit the diffusion of carbon deposition, thereby reducing the occurrence of carbon deposition and improving the stability and life of the catalyst; the confinement effect can form an isolation layer on the catalyst surface, reducing or blocking the contact between toxic substances and the catalyst, thereby reducing the risk of poisoning. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the BET diagram of ZSM-5 before and after alkali treatment in Example 1;

[0024] Figure 2 TEM image of ZSM-5 before alkali treatment in Example 1;

[0025] Figure 3 This is the TEM image of ZSM-5 after alkali treatment in Example 1. DETAILED DESCRIPTION

[0026] The present invention provides a VOCs catalyst, comprising a modified ZSM-5 zeolite molecular sieve and an active metal loaded on the modified ZSM-5 zeolite molecular sieve;

[0027] The preparation method of the modified ZSM-5 zeolite molecular sieve comprises the following steps:

[0028] The ZSM-5 zeolite molecular sieve and the organic base solution are mixed and then subjected to a hydrothermal reaction to obtain a ZSM-5 zeolite molecular sieve loaded with an organic base;

[0029] The organic base-loaded ZSM-5 zeolite molecular sieve is calcined to remove the organic base, thereby obtaining the modified ZSM-5 zeolite molecular sieve;

[0030] The organic alkali solution is tetrapropylammonium hydroxide solution.

[0031] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known in the art.

[0032] The invention mixes a ZSM-5 zeolite molecular sieve and an organic base solution and then performs a hydrothermal reaction to obtain a ZSM-5 zeolite molecular sieve loaded with an organic base.

[0033] Before the mixing, the present invention preferably calcines the ZSM-5 zeolite molecular sieve.

[0034] In the present invention, the calcination temperature is preferably 550° C. and the calcination time is preferably 3 hours. Calcination removes impurities in the ZSM-5 zeolite molecular sieve.

[0035] In the present invention, the ratio of the mass of the ZSM-5 zeolite molecular sieve to the amount of organic base in the organic base solution is preferably 5g: 0.4~1mol. In a specific embodiment of the present invention, the ratio of the mass of the ZSM-5 zeolite molecular sieve to the amount of organic base in the organic base solution can be 5g: 0.4mol / L, 5g: 0.7mol / L or 5g: 1mol / L; the silicon-aluminum ratio of the ZSM-5 zeolite molecular sieve is preferably 25~80. In a specific embodiment of the present invention, the silicon-aluminum ratio can be 25, 30, 40, 50, 60, 70 or 80; the ZSM-5 zeolite molecular sieve includes H-ZSM-5 zeolite molecular sieve and / or Na-ZSM-5 zeolite molecular sieve.

[0036] In the present invention, the mixing is preferably carried out under the condition of magnetic stirring, the speed of the magnetic stirring is preferably 500 r / min, and the time is preferably 5 h.

[0037] In the present invention, the temperature of the hydrothermal reaction is preferably 170° C., and the time is preferably 72 h.

[0038] After the hydrothermal reaction, the Si of the molecular sieve is dissolved and defects are formed on the surface, which is beneficial to the anchoring of the metal.

[0039] After the hydrothermal reaction, the present invention preferably cools the obtained product to room temperature naturally and then filters it, washes, filters and dries the obtained solid to obtain the organic base-loaded ZSM-5 zeolite molecular sieve.

[0040] The present invention has no particular limitation on the washing, and washing with alcohol and water until neutrality is sufficient. In a specific embodiment of the present invention, washing is performed three times with alcohol and twice with ultrapure water.

[0041] In the present invention, the drying temperature is preferably 60° C. and the drying time is preferably 12 hours.

[0042] After obtaining the organic base-loaded ZSM-5 zeolite molecular sieve, the present invention calcines the organic base-loaded ZSM-5 zeolite molecular sieve to remove the organic base, thereby obtaining the modified ZSM-5 zeolite molecular sieve.

[0043] In the present invention, the calcination temperature is preferably 550° C. and the calcination time is preferably 6 hours.

[0044] In the present invention, the mass ratio of the total active metal element mass in the active metal and / or active metal oxide to the modified ZSM-5 zeolite molecular sieve is preferably 1:0.005-0.01; the active metal preferably includes platinum and / or palladium.

[0045] The present invention also provides a method for preparing the VOCs catalyst described in the above technical solution, comprising the following steps:

[0046] The modified ZSM-5 zeolite molecular sieve, water and an acid solution or a salt solution corresponding to an active metal element are mixed, and then the water in the obtained mixture is removed and then calcined to obtain the VOCs catalyst.

[0047] In the present invention, the mixing preferably includes: mixing the modified ZSM-5 zeolite molecular sieve with water and then mixing with an acid solution or a salt solution corresponding to the active metal element.

[0048] In the present invention, the removing preferably comprises rotary evaporation followed by drying.

[0049] In the present invention, the temperature of the rotary evaporation is preferably 800° C. The present invention has no particular limitation on the time of the rotary evaporation, as long as the water is removed.

[0050] In the present invention, the drying temperature is preferably 100° C. and the drying time is preferably 12 hours.

[0051] In the present invention, the calcination temperature is preferably 550° C., and the calcination time is preferably 3 h; and the calcination is preferably carried out in air.

[0052] After the calcination, reduction is preferably performed.

[0053] In the present invention, the reduction is preferably carried out in a mixed atmosphere of H2 and N2, in which the volume content of H2 is preferably 10%, the reduction temperature is preferably 400-800°C, and the time is preferably 1-3h; in a specific embodiment of the present invention, the reduction temperature can be 400°C, 500°C, 600°C, 700°C or 800°C, and the time can be 1h, 2h or 3h.

[0054] The present invention also provides the use of the VOCs catalyst described in the above technical solution or the VOCs catalyst prepared by the preparation method described in the above technical solution in treating tail gas containing VOCs.

[0055] In the present invention, the application preferably includes:

[0056] The VOCs catalyst is placed in a fixed bed and a catalytic reaction is carried out in the tail gas containing VOCs.

[0057] In the present invention, the temperature of the catalytic reaction is preferably 150 to 390° C., and the catalytic reaction is preferably carried out under anhydrous conditions.

[0058] The VOCs catalyst provided by the present invention, its preparation method and application are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0059] Example 1

[0060] 1): Weigh 5 g of H-ZSM-5 zeolite molecular sieve with a silicon-aluminum ratio of 50 (specific surface area of ​​325.87 m 2 / g, with an average pore size of 8.9nm, i.e., ZSM-5 before alkali treatment) was placed in a muffle furnace and calcined for 3h at a calcination temperature of 550°C;

[0061] 2): Take 56.9408 mL of 0.7 mol / L tetrapropylammonium hydroxide solution into a volumetric flask, add ultrapure water to make the volume 100 mL, pour into a beaker, add the above-mentioned calcined molecular sieve, and then place on a magnetic stirrer at a speed of 500 r / min and stir for 5 h to obtain solution A;

[0062] 3): Pour the prepared solution into the polytetrafluoroethylene liner and seal it. The poured solution should not exceed two-thirds of the volume of the liner. Perform hydrothermal treatment in an oven at 170°C for 72 hours. Open the reactor after it cools to room temperature.

[0063] 4): Pour out the solution in the reactor cooled to room temperature, wash the solution with alcohol three times and ultrapure water twice until it is neutral, then filter it, collect the product by filtration, and dry the product in a 60°C oven for 12 hours. After drying, put the sample in a muffle furnace and roast it at 550°C for 6 hours. After the roasting is completed, the defective H-ZSM-5 zeolite molecular sieve (ZSM-5 after alkali treatment) will be obtained;

[0064] 5): Weigh 2g of the prepared H-ZSM-5 defective molecular sieve, add deionized water to dissolve it, take out 1mL of H2PtCl6 solution with a concentration of 0.9mol / L, and add it to the dissolved molecular sieve, then place it on a magnetic stirrer with a speed of 500r / min and stir for 2h. The mass ratio of the carrier to the Pt ion in the solution is 1:0.01. Pour the stirred solution into a rotary evaporator, remove excess water by rotary evaporation at 80°C, and then put it into a 100°C oven to dry for 12h. After drying, the obtained sample is calcined at 550°C in an air atmosphere for 3h to obtain a Pt / defective ZSM-5 catalyst.

[0065] Application Example 1

[0066] The catalyst prepared in Example 1 was used for VOCs catalytic oxidation experiment. The temperature of the quartz tube reactor was controlled at 300°C using a resistance furnace, and the activity of the catalyst was evaluated on a fixed bed continuous evaluation device. The device uses a quartz tube reactor with a specification of Φ8×200mm. A reaction gas containing VOCs standard gas, pure O2 and balanced N2 is introduced into a fixed bed reactor with a total flow rate of 50mL / min. The VOCs concentration in the reaction gas is 600ppm, the O2 content is 21vol.%, and N2 is the balance gas. The space velocity (GHSV) of the catalytic oxidation is 15000mL / (g·h). 0.20g of catalyst (40-60 mesh) was used in the test. The terminal gas enters a GC equipped with a TCD and FID detector. The temperature when the toluene conversion rate is tested is 80% is 195°C, the temperature when it is 90% is 205°C, and the temperature when it is 100% is 220°C (the lower the temperature, the better the performance of the catalyst).

[0067] Comparative Example 1

[0068] Weigh 2 g of H-ZSM-5 zeolite molecular sieve with a silicon-aluminum ratio of 50 (specific surface area of ​​325.87 m 2 / g, average pore size of 8.9nm), add deionized water to dissolve it, take out 1mL of H2PtCl6 solution with a concentration of 0.9mol / L, and add it to the dissolved molecular sieve, then place it on a magnetic stirrer with a speed of 500r / min and stir for 2h. The mass ratio of the carrier to the Pt ion in the solution is 1:0.01. Pour the stirred solution into a rotary evaporator, remove excess water by rotary evaporation at 80℃, and then put it into a 100℃ oven for drying for 12h. After drying, the obtained sample is calcined at 550℃ in air atmosphere for 3h, so as to obtain a Pt / ZSM-5 catalyst.

[0069] Comparative application example 1

[0070] The only difference from Application Example 1 is that the catalyst of Comparative Example 1 is used, and the rest is the same as Application Example 1.

[0071] The temperature at which the toluene conversion rate was 100% was 250°C.

[0072] Example 2

[0073] 1): Weigh 5 g of H-ZSM-5 zeolite molecular sieve with a silicon-aluminum ratio of 50 (specific surface area of ​​325.87 m 2 / g, average pore size of 8.9 nm) was placed in a muffle furnace and calcined for 3 h at a temperature of 550 ° C;

[0074] 2): Take 56.9408 mL of 0.7 mol / L tetrapropylammonium hydroxide solution into a volumetric flask, add ultrapure water to make the volume 100 mL, pour into a beaker, add the above-mentioned calcined molecular sieve, and then place on a magnetic stirrer at a speed of 500 r / min and stir for 5 h to obtain solution A;

[0075] 3): Pour the prepared solution into the polytetrafluoroethylene liner and seal it. The poured solution should not exceed two-thirds of the volume of the liner. Perform hydrothermal treatment in an oven at 170°C for 72 hours. Open the reactor after it cools to room temperature.

[0076] 4): Pour out the solution in the reactor cooled to room temperature, wash the solution with alcohol three times and ultrapure water twice until it is neutral, then filter it, collect the product by filtration, and dry the product in a 60°C oven for 12 hours. After drying, put the sample in a muffle furnace and roast it at 550°C for 6 hours. After the roasting is completed, the defective H-ZSM-5 zeolite molecular sieve will be obtained;

[0077] 5): Weigh 2g of the prepared H-ZSM-5 defective molecular sieve, add deionized water to dissolve it, take out 1mL of H2PtCl6 solution with a concentration of 0.9mol / L, and add it to the dissolved molecular sieve, then place it on a magnetic stirrer with a speed of 500r / min and stir for 2h. The mass ratio of the carrier to the Pt ion in the solution is 1:0.01. Pour the stirred solution into a rotary evaporator, remove excess water by rotary evaporation at 80°C, and then put it into a 100°C oven to dry for 12h. After drying, the obtained sample is calcined at 550°C in an air atmosphere for 3h to obtain a Pt / defective ZSM-5 catalyst;

[0078] 6): Treat the Pt / defective ZSM-5 catalyst in a mixed atmosphere of H2 and N2 (H2 volume content is 10%) for 2 hours at a treatment temperature of 500°C, and the desired catalyst is now prepared.

[0079] Application Example 2

[0080] The only difference from Application Example 1 is that the catalyst of Example 2 is used, and the rest is the same as Application Example 1.

[0081] The temperature at which the toluene conversion rate was tested to be 100% was 210°C.

[0082] Comparative Example 2

[0083] Weigh 2 g of H-ZSM-5 zeolite molecular sieve with a silicon-aluminum ratio of 50 (specific surface area of ​​325.87 m 2 / g, average pore size of 8.9nm), add deionized water to dissolve it, take out 1mL of H2PtCl6 solution with a concentration of 0.9mol / L, and add it to the above-dissolved molecular sieve, then place it on a magnetic stirrer with a speed of 500r / min and stir for 2h. The mass ratio of the carrier to the Pt ion in the solution is 1:0.01. Pour the stirred solution into a rotary evaporator, remove excess water by rotary evaporation at 80°C, and then put it into a 100°C oven for drying for 12h. After drying, the obtained sample is calcined at 550°C in an air atmosphere for 3h, and a Pt / defective ZSM-5 catalyst is obtained. The Pt / ZSM-5 catalyst is treated for 2h in a mixed atmosphere of H2 and N2 (H2 volume content is 10%), and the treatment temperature is 500°C, so that the required catalyst preparation is completed.

[0084] Comparative Application Example 2

[0085] The only difference from Application Example 1 is that the catalyst of Comparative Example 2 is used, and the rest is the same as Application Example 1.

[0086] The temperature at which the toluene conversion rate was 100% was 250°C.

[0087] Comparative Example 3

[0088] 1): Take 5g of H-ZSM-5 zeolite molecular sieve with a silicon-aluminum ratio of 50 (specific surface area of ​​325.87m 2 / g, average pore size of 8.9nm) was placed in a muffle furnace and calcined for 3h at a calcination temperature of 550°C.

[0089] 2): Take 56.9408mL of 0.7mol / L tetrapropylammonium hydroxide (TPAOH) solution into a volumetric flask, add ultrapure water to make the volume 100mL. Pour the solution into a beaker, add the above-mentioned calcined molecular sieve, and then place it on a magnetic stirrer at a speed of 500r / min and stir for 5h to obtain solution A.

[0090] 3): Take 56.9408mL of 0.7mol / L sodium hydroxide (NaOH) solution into another volumetric flask, add ultrapure water to make the volume 100mL. Pour the solution into another beaker, add the calcined molecular sieve, and then place it on a magnetic stirrer at a speed of 500r / min and stir for 5h to obtain solution B.

[0091] 4): Pour solution A, solution B and molecular sieve into the polytetrafluoroethylene liner and seal it. The poured solution shall not exceed two-thirds of the volume of the liner. Carry out hydrothermal treatment in an oven at a temperature of 170°C for 72 hours. Open the reactor after it cools to room temperature.

[0092] 5): Pour out the solution in the reactor cooled to room temperature, wash the solution with alcohol three times and ultrapure water twice until it is neutral, then filter and collect the product, and dry the product in a 60°C oven for 12 hours. After drying, place the sample in a muffle furnace and calcine at 550°C for 6 hours. After the calcination is completed, a defective H-ZSM-5 zeolite molecular sieve will be obtained.

[0093] 6): Weigh 2g of the prepared H-ZSM-5 defective molecular sieve and add deionized water to dissolve it. Take out 1mL of H2PtCl6 solution with a concentration of 0.9mol / L and add it to the dissolved molecular sieve, then place it on a magnetic stirrer with a speed of 500r / min and stir for 2h. The mass ratio of the carrier to the Pt ion in the solution is 1:0.01. Pour the stirred solution into a rotary evaporator, remove excess water by rotary evaporation at 80°C, and then put it in a 100°C oven to dry for 12h. After drying, the obtained sample is calcined at 550°C in an air atmosphere for 3h to obtain a Pt / defective ZSM-5 catalyst.

[0094] 7): Treat the Pt / defective ZSM-5 catalyst in a mixed atmosphere of H2 and N2 (H2 volume content is 10%) for 2 hours at a treatment temperature of 500°C, and the desired catalyst is now prepared.

[0095] Comparative Application Example 3

[0096] The only difference from Application Example 1 is that the catalyst of Comparative Example 3 is used, and the rest is the same as Application Example 1.

[0097] The test temperature when the toluene conversion rate was 80% was 205°C, the temperature when it was 90% was 210°C, and the temperature when it was 100% was 220°C.

[0098] The catalytic performance of the defective catalyst prepared by combining tetrapropylammonium hydroxide (TPAOH) and sodium hydroxide (NaOH) is significantly reduced compared to the defective catalyst prepared by using only tetrapropylammonium hydroxide. Although the two can act together on the H-ZSM-5 zeolite molecular sieve to generate defect sites during hydrothermal treatment, sodium hydroxide may introduce additional ion interference, resulting in damage to the acidity and pore structure of the catalyst, thereby affecting the catalyst activity of the catalytic process. Therefore, the defective catalyst prepared using only tetrapropylammonium hydroxide performs better in catalytic activity and stability.

[0099] Figure 1 This is the BET diagram of ZSM-5 before and after alkali treatment in Example 1.

[0100] Depend on Figure 1 It can be seen that the pore size distribution of the defective H-ZSM-5 zeolite molecular sieve in Example 1 has changed significantly, and the micropores have increased.

[0101] The content of micropores in ZSM-5 before alkali treatment is relatively low, indicating that the present invention can achieve confined treatment of the catalyst through tetrapropylammonium hydroxide treatment, thereby providing more space for metal loading.

[0102] Figure 2 is a TEM image of ZSM-5 before alkali treatment in Example 1, Figure 3 This is the TEM image of ZSM-5 after alkali treatment in Example 1.

[0103] Depend on Figures 2-3 It can be seen that the defective H-ZSM-5 zeolite molecular sieve of Example 1 has more defects after being treated with tetrapropylammonium hydroxide.

[0104] The catalyst prepared in Comparative Example 1 did not form defects without alkali treatment, indicating that the present invention can form defects on the catalyst through tetrapropylammonium hydroxide treatment, thereby forming a confinement effect on the active components.

[0105] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A VOCs catalyst, characterized in that: It comprises a modified ZSM-5 zeolite molecular sieve and an active metal and / or an active metal oxide loaded on the modified ZSM-5 zeolite molecular sieve; The preparation method of the modified ZSM-5 zeolite molecular sieve comprises the following steps: The ZSM-5 zeolite molecular sieve and the organic base solution are mixed and then subjected to a hydrothermal reaction to obtain a ZSM-5 zeolite molecular sieve loaded with an organic base; The organic base-loaded ZSM-5 zeolite molecular sieve is calcined to remove the organic base, thereby obtaining the modified ZSM-5 zeolite molecular sieve; The organic alkali solution is tetrapropylammonium hydroxide solution.

2. The VOCs catalyst according to claim 1, characterized in that The silicon-aluminum ratio of the ZSM-5 zeolite molecular sieve is 25-85.

3. The VOCs catalyst according to claim 1 or 2, characterized in that: The ZSM-5 zeolite molecular sieve includes H-ZSM-5 zeolite molecular sieve and / or Na-ZSM-5 zeolite molecular sieve.

4. The VOCs catalyst according to claim 1 or 2, characterized in that: The ratio of the mass of the ZSM-5 zeolite molecular sieve to the amount of the organic base in the organic base solution is 5 g: 0.4-1 mol.

5. The VOCs catalyst according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 170° C. and the time is 72 h.

6. The VOCs catalyst according to claim 1, characterized in that: The calcination temperature is 550° C. and the calcination time is 6 hours.

7. The VOCs catalyst according to claim 1, characterized in that: The active metal includes platinum and / or palladium.

8. The VOCs catalyst according to claim 1 or 7, characterized in that: The mass ratio of the total active metal elements in the active metal and / or active metal oxide to the modified ZSM-5 zeolite molecular sieve is 1:0.005-0.

01.

9. The method for preparing the VOCs catalyst according to any one of claims 1 to 8, characterized in that: The following steps are involved: The modified ZSM-5 zeolite molecular sieve, water and an acid solution or a salt solution corresponding to an active metal element are mixed, and then the water in the obtained mixture is removed and then calcined to obtain the VOCs catalyst.

10. Use of the VOCs catalyst according to any one of claims 1 to 8 or the VOCs catalyst prepared by the preparation method according to claim 9 in treating tail gas containing VOCs.

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