CN113145150B - A nitrogen-enriched hollow hybrid carbon catalytic material and its preparation method and application - Google Patents

Abstract

A nitrogen-enriched hollow hybrid carbon catalytic material and a preparation method and application thereof are disclosed, wherein Mn-Zn-ZIF and a triblock copolymer are added into deionized water to obtain a solution I; dissolving 1,3,5 trimethylbenzene and ammonia water in absolute ethyl alcohol to form a transparent solution II; mixing the solution I and the solution II to obtain a mixed solution, adding the mixed solution into an aqueous solution of dopamine hydrochloride, and reacting to obtain Mn-Zn-ZIF @ PDA; and carbonizing the Mn-Zn-ZIF @ PDA in an inert atmosphere to obtain the nitrogen-enriched hollow hybrid carbon catalytic material. The material has high nitrogen content, high specific surface area, high pore volume and rich adsorption and active sites on the surface, can obviously improve the degradation efficiency of toluene and can effectively inhibit a secondary pollutant O when used for the low-temperature plasma coordinated catalytic degradation of toluene ₃ Is generated.

Description

A nitrogen-enriched hollow hybrid carbon catalytic material and its preparation method and application

technical field

The invention relates to a low-temperature plasma synergistic catalytic oxidation volatile organic compound (VOCs) material, in particular to a nitrogen-enriched hollow hybrid carbon catalytic material, a preparation method and an application.

Background technique

As a class of important indoor and air pollutants, VOCs pose a huge threat to the environment and human health. Toluene (C ₇ H ₈ ) is not only a typical VOC emitted during industrial production, but also an important raw material for the synthesis of organic chemicals. It is considered to be a highly polluting molecule and an important precursor for the formation of photochemical smog and organic aerosols. Therefore, the emission control of C ₇ H ₈ has been widely concerned by researchers around the world. Nowadays, a variety of technologies have been used to remove VOCs, such as physical adsorption, chemical absorption, high-temperature incineration, and catalytic oxidation. However, the above-mentioned traditional VOCs treatment technology has the disadvantages of high energy consumption, high cost and relatively low treatment efficiency for low-concentration (<1000ppmv) and large-flow exhaust gas. In recent years, low-temperature plasma synergistic catalysis technology has been considered as an effective method to purify high-flow, low-concentration VOCs-containing exhaust gas.

At present, the materials used in low-temperature plasma synergistic catalysis are mostly transition metal oxides or noble metal nanoparticle-supported catalysts, but these catalysts often have low specific surface area, high price, and are easily poisoned, deactivated and difficult to regenerate after reaction. Therefore, the development of low-temperature plasma synergistic catalysts with high specific surface area, affordable price and recyclability is particularly important for the development of low temperature plasma synergistic catalytic oxidation of VOCs technology. Multi-element hybrid porous carbon-based materials have developed pores, low specific gravity, abundant catalytic active sites, good thermal and chemical stability, excellent adsorption performance, etc., which can make VOCs and plasma intermediate reactive species in the The adsorption and reaction in its pores can improve the degradation efficiency of VOCs and suppress secondary pollutants. Nitrogen-enriched hybrid carbon materials are a current research hotspot. Recent studies have shown that the introduction of other elements in carbon materials can significantly improve the catalytic activity, electrical conductivity, and surface acidity and alkalinity of the material surface. In most cases, the introduction of nitrogen or other metal elements into carbon materials requires different post-treatment processes, such as high-temperature activation of ammonia gas, impregnation of metal salt solutions, etc., but the nitrogen content introduced in the post-treatment process is low, the distribution of metal particles is uneven, and it is easy to agglomerate However, the original pores of the carbon-based material are blocked and the prepared material has no cavity structure. In order to overcome the above shortcomings, nitrogen-enriched hybrid carbon-based materials were prepared with metal-organic frameworks (MOFs) as precursors to obtain nitrogen-doped and uniformly dispersed metal nanoparticles.

However, the carbon-based materials prepared by using MOF as raw materials have low nitrogen introduction and undeveloped pore structure; and they are rarely used in the field of low-temperature plasma synergistic catalysis.

Contents of the invention

In order to overcome the problems in the prior art, the object of the present invention is to provide a nitrogen-enriched hollow hybrid carbon material and its preparation method and application. The nitrogen-enriched hollow hybrid carbon material prepared by the method has a super large cavity ( ~200nm), uniform, regular, dispersed micro-morphology, high pore structure, abundant catalytic active sites and other advantages can efficiently synergize with low-temperature plasma catalytic degradation of toluene and effectively inhibit O ₃ generation.

In order to achieve the above object, the technical scheme of the present invention is specifically as follows:

A method for preparing a nitrogen-enriched hollow hybrid carbon catalytic material, comprising the following steps:

(1) Add Mn-Zn-ZIF and triblock copolymer to deionized water to obtain solution I;

Dissolve 1,3,5 trimethylbenzene and ammonia water in absolute ethanol to form a transparent solution II;

Mix solution I and solution II to obtain a mixed solution, then add the mixed solution to the aqueous solution of dopamine hydrochloride, and after the reaction, Mn-Zn-ZIF@PDA is obtained;

(2) Mn-Zn-ZIF@PDA was carbonized under an inert atmosphere to obtain a nitrogen-enriched hollow hybrid carbon catalytic material.

The further improvement of the present invention is that Mn-Zn-ZIF is prepared by the following process: zinc nitrate hexahydrate and manganese nitrate are dissolved in methanol to form a uniform metal solution; then the metal solution is added to the methanol solution of 2-methylimidazole medium; standing at 0-80° C. for 12-36 hours, filtering, washing, and drying to obtain Mn-Zn-ZIF.

The further improvement of the present invention lies in that the concentration of zinc nitrate hexahydrate in the metal solution is 80-120 mmol/L; the concentration of manganese nitrate in the metal solution is 0-133 mmol/L.

The further improvement of the present invention lies in that the concentration of manganese nitrate in the metal solution is 40-133mmol/L.

The further improvement of the present invention is that the molar ratio of metal solution Zn ²⁺ to Mn ²⁺ is 1:(0.33～1.33); the concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole is 480～600mmol/L ; The volume ratio of the metal solution to the methanol solution of 2-methylimidazole is 1:(0.5～5).

The further improvement of the present invention lies in that the reaction temperature is 0-60° C., and the reaction time is 24-72 hours.

The further improvement of the present invention is that the mass concentration of Mn-Zn-ZIF in solution I is 0.5-1.5%; the mass concentration of triblock copolymer in solution I is 0-2.5%; The volume ratio of toluene and dehydrated alcohol is (0～0.15):1; The volume ratio of ammoniacal liquor and dehydrated alcohol is (0.025～0.5):1 in the solution II; The mass concentration of dopamine in the aqueous solution of described dopamine hydrochloride is 1 to 3%.

The further improvement of the present invention lies in that the mass concentration of the triblock copolymer in solution I is 1-2.5%; the volume ratio of 1,3,5 trimethylbenzene and absolute ethanol in solution II is (0.1-0.15):1.

The further improvement of the present invention lies in that the volume ratio of solution I, solution II and the aqueous solution of dopamine hydrochloride is (1-2):1:(0.5-1).

The further improvement of the present invention is that the tri-block copolymer is F127; the inert gas flow rate is 200-500mL/min; the temperature is raised from room temperature to the carbonization temperature at a heating rate of 1-5°C/min; the carbonization temperature is 400-800°C , the time is 2-4 hours; the inert atmosphere is N ₂ , Ar or He.

A nitrogen-enriched hollow hybrid carbon catalytic material prepared according to the above method, the material is in the form of monodisperse hollow rounded cubes, the particle size range is 200-400nm, the nitrogen element content is 20-30%, and the specific surface area is 1000-1500m ² /g.

The application of a nitrogen-enriched hollow hybrid carbon catalytic material prepared according to the above method in low-temperature plasma catalytic oxidation of volatile organic compounds.

Preferably, in step 1, the metal solution and the methanol solution of 2-methylimidazole are mixed and reacted at a temperature of 20-30° C. for 24-36 hours to obtain Mn-Zn-ZIF.

Preferably, the solute of solution I in step 2 is Mn-Zn-ZIF and F127 or Mn-Zn-ZIF. That is, the solute of solution I is Mn-Zn-ZIF, and does not contain F127.

Preferably, the solute of solution II in step 2 is 1,3,5 trimethylbenzene and concentrated ammonia water or concentrated ammonia water. That is, solution II may not contain 1,3,5-trimethylbenzene.

Preferably, in step 2, the mixed solution is mixed again with the aqueous solution of dopamine hydrochloride and reacted at a temperature of 20-30° C. for 48-72 hours to obtain Mn-Zn-ZIF@PDA.

The nitrogen source of the catalytic material of the present invention comes from both the core of Mn-Zn-ZIF and the shell of PDA. The hybridization elements of the catalytic material include N, O, Zn and Mn.

Preferably, the nitrogen-enriched hollow hybrid carbon catalytic material can efficiently degrade toluene and effectively suppress the generation of ozone (O ₃ ).

Compared with the prior art, the present invention has the beneficial effects:

The present invention uses dopamine as the carbon source, nitrogen source and shell precursor of the nitrogen-enriched hollow hybrid carbon material, Mn-Zn-ZIF as its own template, and prepares the nitrogen-enriched hollow hybrid carbon material by means of a self-sacrificing template. The dopamine used in the present invention is safe and non-toxic, has a wide source, sustainable regeneration, less environmental pollution, excellent biological activity and high carbonization rate; the material that can be prepared by the present invention has a high specific surface area and abundant and uniform catalytic active sites Point; the technological process of the present invention is safe and convenient, does not need expensive equipment, and the operation flow is simple.

The nitrogen-enriched hollow hybrid carbon material has a particle size of 200-400nm and a shell thickness of about 50nm. It has high nitrogen content, highly dispersed regular morphology, high specific surface area (1159m ² /g), and high pore volume (1.1cm ³ /g) , the heteroelements (N, O, Zn, and Mn) contained on the surface are evenly distributed and have abundant adsorption and catalytic active sites, which can be used for the efficient degradation of industrial VOCs and other adsorption or catalytic fields. The nitrogen-enriched hollow hybrid carbon material prepared by the invention overcomes the disadvantages of low specific surface area, high cost and uneven distribution of catalytic active sites of traditional plasma synergistic catalytic materials.

Applying the nitrogen-enriched hollow hybrid carbon material prepared in the present invention to low-temperature plasma for synergistic catalytic degradation of toluene has high activity and can effectively suppress the generation of O ₃ in the reaction process.

Description of drawings

Fig. 1 is the SEM figure of the Zn-ZIF that embodiment 1 obtains;

Fig. 2 is the SEM figure of the Mn-Zn-ZIF that embodiment 2 obtains;

Fig. 3 is the SEM figure of the Mn-Zn-ZIF that embodiment 3 obtains;

Fig. 4 is the SEM picture of the nitrogen-enriched hollow hybrid carbon catalytic material that embodiment 4 obtains;

Fig. 5 is the SEM figure of the nitrogen-enriched hollow hybrid carbon catalytic material that embodiment 5 obtains;

Fig. 6 is the SEM picture of the nitrogen-enriched hollow hybrid carbon catalytic material that embodiment 6 obtains;

Fig. 7 is the TEM picture of the nitrogen-enriched hollow hybrid carbon catalytic material that embodiment 6 obtains;

Fig. 8 is the EDS spectrogram of the nitrogen-enriched hollow hybrid carbon catalytic material obtained in Example 6;

Figure 9 shows the efficiency of the nitrogen-enriched hollow hybrid carbon catalytic material obtained in Example 7 to degrade toluene with low-temperature plasma and low-temperature plasma alone under different specific input energies;

Fig. 10 shows the concentration of O ₃ produced by each system under different specific input energies of the nitrogen-enriched hollow hybrid carbon catalytic material obtained in Example 7 in conjunction with low-temperature plasma and low-temperature plasma alone.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings.

A method for preparing a nitrogen-enriched hollow hybrid carbon material of the present invention is completed in the following steps:

1. Preparation of manganese (Mn) zinc (Zn) bimetallic organic framework (Mn-Zn-ZIF):

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ 6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; pour the metal solution quickly and with stirring into 2-formazan In the methanol solution of imidazole; stand at a temperature of 0-80°C for 12-36 hours, filter, wash twice with water, wash with methanol for 2-4 times, and then dry at a temperature of 80-120°C for 6-12 Hours, the Mn-Zn-ZIF of polyhedral shape is obtained;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in step 1 is 80-120 mmol/L;

The concentration of Mn(NO ₃ ) ₂ in the metal solution described in step 1 is 0-133mmol/L;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in step 1 is 480～600mmol/L;

The volume ratio of the metal solution described in step 1 to the methanol solution of 2-methylimidazole is 1:(0.5～5);

2. Preparation of polydopamine-coated Mn-Zn-ZIF composite Mn-Zn-ZIF@PDA:

Add the Mn-Zn-ZIF and triblock copolymer (F127) obtained in step 1 into deionized water, and stir while ultrasonically oscillating to fully disperse the polyhedral Mn-Zn-ZIF and F127 to obtain solution I;

Dissolve 1,3,5 trimethylbenzene and concentrated ammonia water (mass fraction 25-28%) in absolute ethanol to form a transparent solution II;

Mix solution I and solution II and stir for 2 to 5 minutes to obtain a mixed solution, then pour the mixed solution into the aqueous solution of dopamine hydrochloride while stirring, and continue to stir for 24 to 72 hours at a temperature of 0 to 60°C; Centrifuge at 7000 rpm, remove the supernatant, and obtain a black powder; use deionized water and methanol as detergents, first ultrasonically clean the black powder for 5 to 30 minutes, then use water as detergent to wash twice, and then wash with water Methanol is used as a detergent for centrifugal washing 2 to 4 times, and then vacuum dried at a temperature of 80 to 120°C for 6 to 12 hours to obtain a composite structure of Mn-Zn-ZIF@PDA;

The mass concentration of Mn-Zn-ZIF in solution I described in step 2 is 0.5-1.5%;

The mass concentration of F127 in solution I described in step 2 is 0-2.5%;

The volume ratio of 1,3,5 trimethylbenzene and absolute ethanol in solution II described in step 2 is (0-0.15):1;

The volume ratio of concentrated ammonia water and absolute ethanol in the solution II described in step 2 is (0.025～0.5):1;

The mass concentration of dopamine in the aqueous solution of dopamine hydrochloride described in step 2 is 1-3%;

The volume ratio of the aqueous solution of solution I, solution II and dopamine hydrochloride described in step 2 is (1～2):1:(0.5～1);

3. Preparation of nitrogen-enriched hollow hybrid carbon catalytic materials:

Put the Mn-Zn-ZIF@PDA obtained in step 2 into a tube furnace for carbonization and activation under an inert atmosphere. The temperature is 400-800° C. for 2-4 hours, and the nitrogen-enriched hollow hybrid carbon catalytic material is obtained.

The beneficial effect of this implementation mode:

1. The technological process of this embodiment is safe and convenient, does not require expensive equipment, and the operation process is simple;

2. The dopamine used in this embodiment is safe and non-toxic, has a wide source, sustainable regeneration, little environmental pollution, excellent biological activity and high carbonization rate;

3. High specific surface area and rich and uniform catalytic active sites have always been important indicators for improving catalyst activity and stability;

4. In this embodiment, dopamine is used as the carbon source, nitrogen source and shell precursor of the nitrogen-enriched hollow hybrid carbon catalytic material, and Mn-Zn-ZIF is used as its own template, and the nitrogen-enriched hollow hybrid is prepared by self-sacrificing template. The carbonized catalytic material has a particle size of 200-400nm and a shell thickness of about 50nm. It has a high nitrogen content, a highly dispersed regular shape, a high specific surface area (1159m ² /g), and a high pore volume (1.1cm ³ /g). Heteroelements (N, O, Zn and Mn) are evenly distributed and have abundant adsorption and catalytic active sites, which can be used for efficient degradation of industrial VOCs and other adsorption or catalytic fields;

5. The nitrogen-enriched hollow hybrid carbon catalytic material prepared in this embodiment overcomes the shortcomings of traditional plasma synergistic catalytic materials such as low specific surface area, high cost and uneven distribution of catalytic active sites;

6. This embodiment is suitable for preparing nitrogen-enriched hollow hybrid carbon catalytic materials;

7. The nitrogen-enriched hollow hybrid carbon catalytic material prepared in this embodiment has high activity and can effectively inhibit the generation of O ₃ in the reaction process when it is applied to low-temperature plasma for synergistic catalytic degradation of toluene.

Preferably, the molar ratio of Zn ²⁺ to Mn ²⁺ in the metal solution in step 1 is 1:(0.33˜1.33).

Preferably, in step 1, the metal solution and the methanol solution of 2-methylimidazole are mixed and reacted at a temperature of 20-30° C. for 24-36 hours to obtain Mn-Zn-ZIF.

Preferably, the solute of solution II in step 2 is 1,3,5 trimethylbenzene and concentrated ammonia water or concentrated ammonia water.

Preferably, in step 2, the mixed solution is mixed again with the aqueous solution of dopamine hydrochloride and reacted at a temperature of 20-30° C. for 48-72 hours to obtain Mn-Zn-ZIF@PDA.

Preferably, the inert atmosphere described in Step 3 is one of N ₂ , Ar and He.

Preferably, the nitrogen-enriched hollow hybrid carbon catalytic material prepared by the method is combined with low-temperature plasma catalytic oxidation of VOCs.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example 1

A kind of method for preparing monodisperse Zn-ZIF, specifically finish according to the following steps:

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; -in a methanol solution of methylimidazole; stand at room temperature for 24 hours, filter, wash twice with water and wash three times with methanol, and then dry at a temperature of 100° C. for 8 hours to obtain Zn-ZIF;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in the step is 100mmol/L;

The concentration of Mn(NO ₃ ) ₂ in the metal solution described in the steps is 0mmol/L;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in the step is 500mmol/L;

The volume ratio of the metal solution described in the step to the methanol solution of 2-methylimidazole is 1:1.

Fig. 1 is the SEM figure of the Zn-ZIF that embodiment 1 obtains; As can be seen from Fig. 1, the prepared Zn-ZIF of embodiment 1 is polyhedral structure, and its particle diameter is 100～200nm, and distribution is uniform, illustrates embodiment 1 The ZIF-like material obtained in the above preparation steps has a regular and uniform morphology, which is beneficial for the preparation of a hollow-structured carbon-based catalytic material using it as its own template as described later.

Example 2

A kind of method for preparing monodisperse Mn-Zn-ZIF, specifically finish according to the following steps:

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; - in a methanol solution of methylimidazole; stand at room temperature for 24 hours, filter, wash twice with water and wash three times with methanol, and then dry at 100°C for 8 hours to obtain Mn-Zn-ZIF;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in the step is 100mmol/L;

The concentration of Mn(NO ₃ ) ₂ in the metal solution described in the steps is 10mmol/L;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in the step is 500mmol/L;

The volume ratio of the metal solution described in the step to the methanol solution of 2-methylimidazole is 1:1.

Figure 2 is the SEM image of the Mn-Zn-ZIF obtained in Example 2; as can be seen from Figure 2, the Mn-Zn-ZIF prepared in Example 2 also exhibits polyhedral morphology, uniform dispersion, and a particle size range of 300 to 500nm It is larger than the Zn-ZIF prepared in Example 1, which shows that adding Mn ions in the metal solution described in Example 2 can effectively improve the crystal growth rate and make the Mn-Zn-ZIF particle size larger, which is for the preparation of the following Nitrogen-enriched hollow hybrid carbon catalytic materials with large cavities provide favorable conditions.

Example 3

A kind of method for preparing monodisperse Mn-Zn-ZIF, specifically finish according to the following steps:

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; - in a methanol solution of methylimidazole; stand at room temperature for 24 hours, filter, wash twice with water and wash three times with methanol, and then dry at 100°C for 8 hours to obtain Mn-Zn-ZIF;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in the step is 100mmol/L;

The concentration of Mn(NO ₃ ) ₂ in the metal solution described in the steps is 20mmol/L;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in the step is 500mmol/L;

The volume ratio of the metal solution described in the step to the methanol solution of 2-methylimidazole is 1:1.

Fig. 3 is the SEM figure of the Mn-Zn-ZIF that embodiment 3 obtains; As can be seen from Fig. 3, the Mn-Zn-ZIF prepared by embodiment 3 is also similar to the ZIF of polyhedral morphology and embodiment 1 and 2 gained, but Particle diameter is more than 1000nm, this further illustrates that adding Mn ion amount in the metal solution described in embodiment 3 increases and can effectively improve crystal growth rate and make Mn-Zn-ZIF particle diameter become larger; In the step, the concentration of Mn(NO ₃ ) ₂ in the metal solution is used to control the particle size of the prepared Mn-Zn-ZIF.

Example 4

A method for preparing a nitrogen-enriched hollow hybrid carbon catalytic material, specifically completed according to the following steps:

1. Preparation of manganese (Mn) zinc (Zn) bimetallic organic framework (Mn-Zn-ZIF):

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; - in a methanol solution of methylimidazole; stand at room temperature for 24 hours, filter, wash twice with water and wash three times with methanol, and then dry at 100°C for 8 hours to obtain Mn-Zn-ZIF;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in step 1 is 100mmol/L;

The concentration of Mn(NO ₃ ) ₂ in the metal solution described in step 1 is 10mmol/L;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in step 1 is 500mmol/L;

The volume ratio of the metal solution described in step 1 to the methanol solution of 2-methylimidazole is 1:1.

2. Preparation of polydopamine-coated Mn-Zn-ZIF composite Mn-Zn-ZIF@PDA:

Add the Mn-Zn-ZIF and tri-block copolymer (F127) obtained in step 1 into deionized water, ultrasonically oscillate while stirring to fully disperse the polyhedral-shaped Mn-Zn-ZIF and F127 to obtain solution I; mix 1, Dissolve 3,5 trimethylbenzene and concentrated ammonia water (25-28%) in absolute ethanol to form a transparent solution II; then mix solution I and solution II and stir for 3 minutes to obtain a mixed solution, then pour the mixed solution under stirring Add the aqueous solution of dopamine hydrochloride, then continue to stir at room temperature for 48 hours; centrifuge at 6500 rpm, remove the supernatant to obtain a black powder; use deionized water and methanol as detergents, and ultrasonically clean the black powder for 10 Minutes, washed twice with water, then three times with methanol, and then vacuum-dried at 100°C for 8 hours to obtain a composite structure of Mn-Zn-ZIF@PDA;

The mass concentration of Mn-Zn-ZIF in solution I described in step 2 is 0.8%;

The mass concentration of F127 in solution I described in step 2 is 0; that is, it does not contain F127.

The volume ratio of 1,3,5 trimethylbenzene and absolute ethanol in solution II described in step 2 is 0.125:1;

The volume ratio of concentrated ammonia water and absolute ethanol in the solution II described in step 2 is 0.15:1;

The mass concentration of dopamine in the aqueous solution of dopamine hydrochloride described in step 2 is 2%;

The volume ratio of the aqueous solution of solution I, solution II and dopamine hydrochloride described in step 2 is 1.25:1:0.75;

3. Preparation of nitrogen-enriched hollow hybrid carbon catalytic materials:

Put the Mn-Zn-ZIF@PDA obtained in step 2 into a tube furnace for carbonization and activation under an inert atmosphere. Insulated for 2 hours to obtain a nitrogen-enriched hollow hybrid carbon catalytic material.

Fig. 4 is the SEM image of the nitrogen-enriched hollow hybrid carbon catalytic material obtained in Step 3 of Example 4; as can be seen from Fig. 4, the nitrogen-enriched hollow hybrid carbon catalytic material obtained in Example 4 mostly presents a broken shell-like structure, The main reason may be that the solution I described in step 2 does not add surfactant F127, resulting in uneven and incomplete outer shell PDA-coated inner core Mn-Zn-ZIF, and then a broken shell-like structure after carbonization and activation.

Example 5

A method for preparing a nitrogen-enriched hollow hybrid carbon catalytic material, specifically completed according to the following steps:

1. Preparation of manganese (Mn) zinc (Zn) bimetallic organic framework (Mn-Zn-ZIF):

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; - in a methanol solution of methylimidazole; stand at room temperature for 24 hours, filter, wash twice with water and wash three times with methanol, and then dry at 100°C for 8 hours to obtain Mn-Zn-ZIF;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in step 1 is 100mmol/L;

The concentration of Mn(NO ₃ ) ₂ in the metal solution described in step 1 is 10mmol/L;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in step 1 is 500mmol/L;

The volume ratio of the metal solution described in step 1 to the methanol solution of 2-methylimidazole is 1:1.

2. Preparation of polydopamine-coated Mn-Zn-ZIF composite Mn-Zn-ZIF@PDA:

Add the Mn-Zn-ZIF and tri-block copolymer (F127) obtained in step 1 into deionized water, ultrasonically oscillate while stirring to fully disperse the polyhedral-shaped Mn-Zn-ZIF and F127 to obtain solution I; mix 1, Dissolve 3,5 trimethylbenzene and concentrated ammonia water (25-28%) in absolute ethanol to form a transparent solution II; then mix solution I and solution II and stir for 3 minutes to obtain a mixed solution, then pour the mixed solution under stirring Add the aqueous solution of dopamine hydrochloride, then continue to stir at room temperature for 48 hours; centrifuge at 6500 rpm, remove the supernatant to obtain a black powder; use deionized water and methanol as detergents, and ultrasonically clean the black powder for 10 Minutes, washed twice with water, then three times with methanol, and then vacuum-dried at 100°C for 8 hours to obtain a composite structure of Mn-Zn-ZIF@PDA;

The mass concentration of Mn-Zn-ZIF in solution I described in step 2 is 0.8%;

The mass concentration of F127 in solution I described in step 2 is 2.2%;

The volume ratio of 1,3,5 trimethylbenzene and absolute ethanol in the solution II described in step 2 is 0:1;

The volume ratio of concentrated ammonia water and absolute ethanol in the solution II described in step 2 is 0.15:1;

The mass concentration of dopamine in the aqueous solution of dopamine hydrochloride described in step 2 is 2%;

The volume ratio of the aqueous solution of solution I, solution II and dopamine hydrochloride described in step 2 is 1.25:1:0.75;

3. Preparation of nitrogen-enriched hollow hybrid carbon catalytic materials:

Put the Mn-Zn-ZIF@PDA obtained in step 2 into a tube furnace for carbonization and activation under an inert atmosphere. Insulated for 2 hours to obtain a nitrogen-enriched hollow hybrid carbon catalytic material.

Figure 5 is the SEM image of the nitrogen-enriched hollow hybrid carbon catalytic material obtained in Step 3 of Example 5; it can be seen from Figure 5 that the nitrogen-enriched hollow hybrid carbon catalytic material obtained in Example 5 is a completely coated rounded cube Morphology, the main reason for the above structure and morphology may be that the solution II described in step 2 did not add the pore-enlarging agent 1,3,5 trimethylbenzene, resulting in the shell PDA coating the core Mn-Zn-ZIF intact after carbonization activation No nitrogen-enriched hollow hybrid carbon catalytic material with a broken pore structure was found, which also reduces the porosity of the nitrogen-enriched hollow hybrid carbon catalytic material, which is not conducive to the adsorption and catalysis of pollutants.

Example 6

A method for preparing a nitrogen-enriched hollow hybrid carbon catalytic material, specifically completed according to the following steps:

1. Preparation of manganese (Mn) zinc (Zn) bimetallic organic framework (Mn-Zn-ZIF):

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; - in a methanol solution of methylimidazole; stand at room temperature for 24 hours, filter, wash twice with water and wash three times with methanol, and then dry at 100°C for 8 hours to obtain Mn-Zn-ZIF;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in step 1 is 100mmol/L;

The concentration of Mn(NO ₃ ) ₂ in the metal solution described in step 1 is 10mmol/L;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in step 1 is 500mmol/L;

The volume ratio of the metal solution described in step 1 to the methanol solution of 2-methylimidazole is 1:1.

2. Preparation of polydopamine-coated Mn-Zn-ZIF composite Mn-Zn-ZIF@PDA:

Add the Mn-Zn-ZIF and tri-block copolymer (F127) obtained in step 1 into deionized water, ultrasonically oscillate while stirring to fully disperse the polyhedral-shaped Mn-Zn-ZIF and F127 to obtain solution I; mix 1, Dissolve 3,5 trimethylbenzene and concentrated ammonia water (25-28%) in absolute ethanol to form a transparent solution II; then mix solution I and solution II and stir for 3 minutes to obtain a mixed solution, then pour the mixed solution under stirring Add the aqueous solution of dopamine hydrochloride, then continue to stir at room temperature for 48 hours; centrifuge at 6500 rpm, remove the supernatant to obtain a black powder; use deionized water and methanol as detergents, and ultrasonically clean the black powder for 10 Minutes, washed twice with water, then three times with methanol, and then vacuum-dried at 100°C for 8 hours to obtain a composite structure of Mn-Zn-ZIF@PDA;

The mass concentration of Mn-Zn-ZIF in solution I described in step 2 is 0.8%;

The mass concentration of F127 in solution I described in step 2 is 2.2%;

The volume ratio of 1,3,5 trimethylbenzene and absolute ethanol in solution II described in step 2 is 0.125:1;

The volume ratio of concentrated ammonia water and absolute ethanol in the solution II described in step 2 is 0.15:1;

The mass concentration of dopamine in the aqueous solution of dopamine hydrochloride described in step 2 is 2%;

The volume ratio of the aqueous solution of solution I, solution II and dopamine hydrochloride described in step 2 is 1.25:1:0.75;

3. Preparation of nitrogen-enriched hollow hybrid carbon catalytic materials:

Put the Mn-Zn-ZIF@PDA obtained in step 2 into a tube furnace for carbonization and activation under an inert atmosphere. Insulated for 2 hours to obtain a nitrogen-enriched hollow hybrid carbon catalytic material.

Figure 6 is the SEM image of the nitrogen-enriched hollow hybrid carbon catalytic material obtained in Step 3 of Example 6; it can be seen from Figure 6 that the nitrogen-enriched hollow hybrid carbon catalytic material obtained in Example 6 has a uniform appearance and a particle size range of 200-400nm rounded cubes with different degrees of holes are conducive to the diffusion of pollutants, illustrating the hollow structure of the nitrogen-enriched hollow hybrid carbon catalytic material obtained in Example 6; Figure 7 and Figure 8 are respectively Step 3 of Example 6 The obtained nitrogen-enriched hollow hybrid carbon catalytic material TEM diagram and EDS spectrogram; As can be seen from Figure 7, the nitrogen-enriched hollow hybrid carbon catalytic material shell thickness obtained in Example 6 is 50nm, further illustrating that the catalytic material obtained in Example 6 is Hollow cubic structure with rounded corners; as can be seen from Figure 8, the nitrogen-enriched hollow hybrid carbon catalytic material obtained in Example 6 contains rich nitrogen and hybrid atoms oxygen, zinc and manganese.

Example 7

A method for preparing a nitrogen-enriched hollow hybrid carbon catalytic material and the application of synergistic plasma catalytic degradation of toluene, specifically completed according to the following steps:

1. Preparation of manganese (Mn) zinc (Zn) bimetallic organic framework (Mn-Zn-ZIF):

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; - in a methanol solution of methylimidazole; stand at room temperature for 24 hours, filter, wash twice with water and wash three times with methanol, and then dry at 100°C for 8 hours to obtain Mn-Zn-ZIF;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in step 1 is 100mmol/L;

The concentration of Mn(NO ₃ ) ₂ in the metal solution described in step 1 is 10mmol/L;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in step 1 is 500mmol/L;

The volume ratio of the metal solution described in step 1 to the methanol solution of 2-methylimidazole is 1:1.

2. Preparation of polydopamine-coated Mn-Zn-ZIF composite Mn-Zn-ZIF@PDA:

Add the Mn-Zn-ZIF and tri-block copolymer (F127) obtained in step 1 into deionized water, ultrasonically oscillate while stirring to fully disperse the polyhedral-shaped Mn-Zn-ZIF and F127 to obtain solution I; mix 1, Dissolve 3,5 trimethylbenzene and concentrated ammonia water (25-28%) in absolute ethanol to form a transparent solution II; then mix solution I and solution II and stir for 3 minutes to obtain a mixed solution, then pour the mixed solution under stirring Add the aqueous solution of dopamine hydrochloride, and then continue to stir at room temperature for 48 hours; centrifuge at 6500 rpm, remove the supernatant, and obtain a black powder; use deionized water and methanol as detergents, and ultrasonically clean the black powder for 10 Minutes, centrifugal washing twice with water as detergent, three times with methanol as detergent, and then vacuum-dried at 100°C for 8 hours to obtain Mn-Zn-ZIF@PDA with composite structure;

The mass concentration of Mn-Zn-ZIF in solution I described in step 2 is 0.8%;

The mass concentration of F127 in solution I described in step 2 is 2.2%;

The volume ratio of 1,3,5 trimethylbenzene and absolute ethanol in solution II described in step 2 is 0.125:1;

The volume ratio of concentrated ammonia water and absolute ethanol in the solution II described in step 2 is 0.15:1;

The mass concentration of dopamine in the aqueous solution of dopamine hydrochloride described in step 2 is 2%;

The volume ratio of the aqueous solution of solution I, solution II and dopamine hydrochloride described in step 2 is 1.25:1:0.75;

3. Preparation of nitrogen-enriched hollow hybrid carbon catalytic materials:

Put the Mn-Zn-ZIF@PDA obtained in step 2 into a tube furnace for carbonization and activation under an inert atmosphere. Insulated for 2 hours to obtain a nitrogen-enriched hollow hybrid carbon catalytic material.

4. The application of nitrogen-enriched hollow hybrid carbon (N-HHC) catalytic materials in cooperation with low-temperature plasma for catalytic degradation of toluene:

The N-HHC catalytic material obtained in step 3 is pressed into tablets, and the granular N-HHC obtained by 40-60 mesh sieves is put into the downstream of the dielectric barrier discharge area, and low-concentration toluene (280ppm) is introduced, and the dilution gas is air, and the polluting gas The total flow rate is 500mL/min; no catalyst is placed in the low-temperature plasma reactor as a comparative experiment.

Fig. 9 and Fig. 10 are the toluene degradation efficiency and reaction system produced O concentration of N _- HHC cooperative low-temperature plasma, independent low-temperature plasma (NTP) catalyzed degradation toluene under different specific input energies respectively in step four; It can be seen from Figure 9 that the addition of catalyst N-HHC to the low-temperature plasma reaction device in step four can greatly improve the degradation efficiency of toluene. For example, the specific input energy required for the degradation efficiency of toluene in the N-HHC low-temperature plasma system to be 90% is 281J/ L, and under the same toluene degradation efficiency, the specific input energy required by the NTP system is 357J/L, which may be that the addition of N-HHC catalyst prolongs the contact reaction time between toluene and plasma active species to promote the degradation of toluene; from Fig. 10. It can be seen that the addition of catalyst N-HHC in the low _- temperature plasma reaction device in step 4 is significantly lower than that of NTP in the reaction system. The concentration of O ₃ is 128.7ppm, which is about half of that in the NTP system (261.6ppm), which shows that N-HHC can effectively inhibit and utilize O ₃ to degrade toluene, which can not only improve the degradation efficiency of toluene but also effectively inhibit secondary pollutants O ₃ production.

In the present invention, F127 can make the combination of PDA and Mn-Zn-ZIF intact so as not to cause broken shells, and 1,3,5 trimethylbenzene as a pore-enlarging agent can be a favorable reactant for producing holes of different sizes on the surface of the rounded cube N-HHC and The diffusion of products, in addition, the introduction of abundant heteroatoms on N-HHC provides a large number of adsorption and active sites for catalytic reactions. Therefore, using N-HHC as a catalyst for the synergistic degradation of toluene with low _- temperature plasma and NTP, not only the toluene degradation efficiency is improved but also the secondary pollutant O produced by the system is well suppressed.

Example 8

1. Preparation of manganese (Mn) zinc (Zn) bimetallic organic framework (Mn-Zn-ZIF):

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; pour the metal solution quickly and with stirring into the 2- In methanol solution of methylimidazole; stand at 0°C for 12 hours, filter, wash twice with water, wash with methanol for 2 to 4 times, and then dry at 80°C for 12 hours to obtain Mn-Zn-ZIF;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in step 1 is 80mmol/L;

The concentration of Mn(NO ₃ ) ₂ in the metal solution described in step 1 is 100mmol/L;

The molar ratio of metal solution Zn ²⁺ to Mn ²⁺ is 1:1.25;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in step 1 is 480mmol/L;

The volume ratio of the metal solution described in step 1 to the methanol solution of 2-methylimidazole is 1:0.5.

2. Preparation of polydopamine-coated Mn-Zn-ZIF composite Mn-Zn-ZIF@PDA:

Add the Mn-Zn-ZIF and triblock copolymer (F127) obtained in step 1 into deionized water, and stir while ultrasonically oscillating to fully disperse the polyhedral Mn-Zn-ZIF and F127 to obtain solution I;

Dissolve 1,3,5 trimethylbenzene and concentrated ammonia water (25-28%) in absolute ethanol to form a transparent solution II;

Mix solution I and solution II and stir for 2 minutes to obtain a mixed solution, then pour the mixed solution into the aqueous solution of dopamine hydrochloride while stirring, and then continue to stir at 0°C for 72 hours; centrifuge at 4000 rpm to remove supernatant to obtain a black powder; with deionized water and methanol as detergents, the black powder was ultrasonically cleaned for 5 minutes, water was used as a detergent for centrifugal washing twice, methanol was used as a detergent for centrifugal washing 2 times, and then at temperature Vacuum drying at 120°C for 6 hours to obtain a composite structure of Mn-Zn-ZIF@PDA;

The mass concentration of Mn-Zn-ZIF in solution I described in step 2 is 0.5%;

The mass concentration of F127 in solution I described in step 2 is 2.5%;

The volume ratio of 1,3,5 trimethylbenzene and absolute ethanol in the solution II described in step 2 is 0.1:1;

The volume ratio of concentrated ammonia water and absolute ethanol in the solution II described in step 2 is 0.025:1;

The mass concentration of dopamine in the aqueous solution of dopamine hydrochloride described in step 2 is 1%;

The volume ratio of the aqueous solution of solution I, solution II and dopamine hydrochloride described in step 2 is 1:1:1;

3. Preparation of nitrogen-enriched hollow hybrid carbon catalytic materials:

Put the Mn-Zn-ZIF@PDA obtained in step 2 into a tube furnace for carbonization and activation under _N2 atmosphere, in which the inert gas flow rate is 200mL/min, the heating rate of the device is 1°C/min, and the final temperature is 400 ℃ for 4 hours to obtain a nitrogen-enriched hollow hybrid carbon catalytic material.

Example 9

1. Preparation of manganese (Mn) zinc (Zn) bimetallic organic framework (Mn-Zn-ZIF):

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; pour the metal solution quickly and with stirring into the 2- In methanol solution of methylimidazole; standing reaction at 20°C for 36 hours, filtering, washing twice with water and three times with methanol, and then drying at 120°C for 6 hours to obtain Mn-Zn-ZIF;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in step 1 is 120mmol/L;

The concentration of Mn(NO ₃ ) ₂ in the metal solution described in step 1 is 40mmol/L;

The molar ratio of metal solution Zn ²⁺ to Mn ²⁺ is 1:3;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in step 1 is 600mmol/L;

The volume ratio of the metal solution described in step 1 to the methanol solution of 2-methylimidazole is 1:2.

2. Preparation of polydopamine-coated Mn-Zn-ZIF composite Mn-Zn-ZIF@PDA:

Add the Mn-Zn-ZIF and triblock copolymer (F127) obtained in step 1 into deionized water, and stir while ultrasonically oscillating to fully disperse the polyhedral Mn-Zn-ZIF and F127 to obtain solution I;

Dissolve 1,3,5 trimethylbenzene and concentrated ammonia water (25-28%) in absolute ethanol to form a transparent solution II;

Mix solution I and solution II and stir for 3 minutes to obtain a mixed solution, then pour the mixed solution into the aqueous solution of dopamine hydrochloride while stirring, and then continue to stir at 60°C for 24 hours; centrifuge at 7000 rpm, remove supernatant to obtain a black powder; with deionized water and methanol as detergents, the black powder was ultrasonically cleaned for 15 minutes, water was used as a detergent for centrifugal washing twice, methanol was used as a detergent for centrifugal washing 3 times, and then at temperature Vacuum drying at 100°C for 10 hours to obtain a composite structure of Mn-Zn-ZIF@PDA;

The mass concentration of Mn-Zn-ZIF in solution I described in step 2 is 1%;

The mass concentration of F127 in solution I described in step 2 is 1%;

The volume ratio of 1,3,5 trimethylbenzene and absolute ethanol in the solution II described in step 2 is 0.15:1;

The volume ratio of concentrated ammonia water and absolute ethanol in the solution II described in step 2 is 0.1:1;

The mass concentration of dopamine in the aqueous solution of dopamine hydrochloride described in step 2 is 2%;

The volume ratio of the aqueous solution of solution I, solution II and dopamine hydrochloride described in step 2 is 1:1:0.5;

3. Preparation of nitrogen-enriched hollow hybrid carbon catalytic materials:

Put the Mn-Zn-ZIF@PDA obtained in step 2 into a tube furnace for carbonization and activation under Ar atmosphere, in which the inert gas flow rate is 300mL/min, the heating rate is 2°C/min, and the final temperature is 500°C Insulated for 3 hours to obtain a nitrogen-enriched hollow hybrid carbon catalytic material.

Example 10

1. Preparation of manganese (Mn) zinc (Zn) bimetallic organic framework (Mn-Zn-ZIF):

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; pour the metal solution quickly and with stirring into the 2- In methanol solution of methylimidazole; standing reaction at 40°C for 30 hours, filtering, washing twice with water and four times with methanol, and drying at 110°C for 10 hours to obtain Mn-Zn-ZIF;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in step 1 is 90mmol/L;

The concentration of Mn(NO ₃ ) ₂ in the metal solution described in step 1 is 120mmol/L;

The molar ratio of metal solution Zn ²⁺ to Mn ²⁺ is 3:4;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in step 1 is 500mmol/L;

The volume ratio of the metal solution described in step 1 to the methanol solution of 2-methylimidazole is 1:3.

2. Preparation of polydopamine-coated Mn-Zn-ZIF composite Mn-Zn-ZIF@PDA:

Add the Mn-Zn-ZIF and triblock copolymer (F127) obtained in step 1 into deionized water, and stir while ultrasonically oscillating to fully disperse the polyhedral Mn-Zn-ZIF and F127 to obtain solution I;

Dissolve concentrated ammonia water (25-28%) in absolute ethanol to form a transparent solution II;

Mix solution I and solution II and stir for 4 minutes to obtain a mixed solution, then pour the mixed solution into the aqueous solution of dopamine hydrochloride while stirring, and then continue stirring at 20°C for 60 hours; centrifuge at 5000 rpm, remove supernatant to obtain a black powder; with deionized water and methanol as detergents, the black powder was ultrasonically cleaned for 20 minutes, water was used as a detergent for centrifugal washing twice, methanol was used as a detergent for centrifugal washing 4 times, and then at temperature Vacuum drying at 80°C for 12 hours to obtain a composite structure of Mn-Zn-ZIF@PDA;

The mass concentration of Mn-Zn-ZIF in solution I described in step 2 is 1.5%;

The mass concentration of F127 in solution I described in step 2 is 1.5%;

The volume ratio of concentrated ammonia water and absolute ethanol in the solution II described in step 2 is 0.3:1;

The mass concentration of dopamine in the aqueous solution of dopamine hydrochloride described in step 2 is 3%;

The volume ratio of the aqueous solution of solution I, solution II and dopamine hydrochloride described in step 2 is 2:1:0.7;

3. Preparation of nitrogen-enriched hollow hybrid carbon catalytic materials:

Put the Mn-Zn-ZIF@PDA obtained in step 2 into a tube furnace for carbonization activation under _N2 atmosphere, in which the inert gas flow rate is 400mL/min, the heating rate is 3°C/min, and the final temperature is 600°C Keeping the temperature for 2 hours at lower temperature to obtain a nitrogen-enriched hollow hybrid carbon catalytic material.

Example 11

1. Preparation of manganese (Mn) zinc (Zn) bimetallic organic framework (Mn-Zn-ZIF):

Dissolve zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and manganese nitrate (Mn(NO ₃ ) ₂ ) in methanol to form a homogeneous metal solution; pour the metal solution quickly and with stirring into the 2- In methanol solution of methylimidazole; standing reaction at 80°C for 20 hours, filtering, washing twice with water and twice with methanol, and drying at 100°C for 10 hours to obtain Mn-Zn-ZIF;

The concentration of Zn(NO ₃ ) ₂ ·6H ₂ O in the metal solution described in step 1 is 80mmol/L;

The concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole described in step 1 is 550mmol/L;

The volume ratio of the metal solution described in step 1 to the methanol solution of 2-methylimidazole is 1:5.

2. Preparation of polydopamine-coated Mn-Zn-ZIF composite Mn-Zn-ZIF@PDA:

Add the Mn-Zn-ZIF obtained in step 1 into deionized water, ultrasonically oscillate while stirring to fully disperse the polyhedral Mn-Zn-ZIF to obtain solution I;

Dissolve concentrated ammonia water (25-28%) in absolute ethanol to form a transparent solution II;

Mix and stir solution I and solution II for 5 minutes to obtain a mixed solution, then pour the mixed solution into the aqueous solution of dopamine hydrochloride while stirring, and then continue stirring at 30°C for 50 hours; centrifuge at 6000 rpm, remove supernatant to obtain a black powder; with deionized water and methanol as detergents, the black powder was ultrasonically cleaned for 30 minutes, water was used as a detergent for centrifugal washing twice, methanol was used as a detergent for centrifugal washing 4 times, and then at temperature Vacuum drying at 80°C for 12 hours to obtain a composite structure of Mn-Zn-ZIF@PDA;

The mass concentration of Mn-Zn-ZIF in solution I described in step 2 is 0.7%;

The volume ratio of concentrated ammonia water and absolute ethanol in the solution II described in step 2 is 0.5:1;

The mass concentration of dopamine in the aqueous solution of dopamine hydrochloride described in step 2 is 2%;

The volume ratio of the aqueous solution of solution I, solution II and dopamine hydrochloride described in step 2 is 1.5:1:0.8;

3. Preparation of nitrogen-enriched hollow hybrid carbon catalytic materials:

Put the Mn-Zn-ZIF@PDA obtained in step 2 into a tube furnace for carbonization activation under He atmosphere, in which the inert gas flow rate is 500mL/min, the heating rate is 5°C/min, and the final temperature is 800°C Insulated for 2 hours to obtain a nitrogen-enriched hollow hybrid carbon catalytic material.

The invention relates to the preparation of a MOF-derived carbon-based hollow structure catalytic material and its application in low-temperature plasma catalytic degradation of VOCs. A new type of plasmonic catalytic material with high specific surface area, developed pore structure, rich adsorption and active sites was prepared. The nitrogen-enriched hollow hybrid carbon catalytic material prepared by the present invention has a hollow structure with rounded corners, a particle size of 200-400nm, a shell thickness of about 50nm, regular dispersion, high nitrogen content, high specific surface area, high pore volume, and rich adsorption on the surface. And active sites, which are used in low-temperature plasma coordinated catalytic degradation of toluene can significantly improve the degradation efficiency of toluene and can effectively inhibit the generation of secondary pollutants O ₃ . The invention is suitable for preparing nitrogen-enriched hollow hybrid carbon catalytic materials, and has important applications in the field of catalysis.

Claims (9)

1. A method for preparing a nitrogen-enriched hollow hybrid carbon catalytic material, characterized in that, comprising the following steps: (1) Add Mn-Zn-ZIF and triblock copolymer to deionized water to obtain a solution І; among them, the triblock copolymer is F127; Dissolve 1,3,5 trimethylbenzene and ammonia water in absolute ethanol to form a transparent solution II; wherein, the volume ratio of 1,3,5 trimethylbenzene and absolute ethanol in solution II is (0.1～0.15):1; Mix solution І and solution Ⅱ to obtain a mixed solution, then add the mixed solution to the aqueous solution of dopamine hydrochloride, and after the reaction, Mn-Zn-ZIF@PDA is obtained; wherein, the reaction temperature is 0-60°C, and the time is 24- 72 hours; (2) Carbonize and activate Mn-Zn-ZIF@PDA in an inert atmosphere, where the heating rate is 1-5°C/min, and the final temperature is 400-800°C for 2-4 hours to obtain nitrogen-enriched hollow impurities. Carbonization Catalytic Materials. 2. the preparation method of a kind of nitrogen-enriched hollow hybrid carbon catalytic material according to claim 1 is characterized in that, Mn-Zn-ZIF is obtained by following process: zinc nitrate hexahydrate and manganese nitrate are dissolved in methanol , to form a uniform metal solution; then add the metal solution to the methanol solution of 2-methylimidazole; stand at a temperature of 0-80 ° C for 12-36 hours, filter, wash, and dry to obtain Mn-Zn-ZIF . 3. a kind of preparation method of nitrogen-enriched hollow hybrid carbon catalytic material according to claim 2, is characterized in that, the concentration of zinc nitrate hexahydrate in the metal solution is 80～120 mmol/L; Manganese nitrate in the metal solution The concentration is 40～133mmol/L. 4. the preparation method of a kind of nitrogen-enriched hollow hybrid carbon catalytic material according to claim 2, is characterized in that, the mol ratio of metal solution Zn ²⁺ and Mn ²⁺ is 1:(0.33～1.33); 2 - The concentration of 2-methylimidazole in the methanol solution of methylimidazole is 480-600 mmol/L; the volume ratio of the metal solution to the methanol solution of 2-methylimidazole is 1:(0.5-5). 5. The preparation method of a nitrogen-enriched hollow hybrid carbon catalytic material according to claim 1, characterized in that the mass concentration of Mn-Zn-ZIF in the solution І is 0.5 to 1.5%; The mass concentration of segment copolymer is 1-2.5%; the volume ratio of ammonia water to absolute ethanol in solution II is (0.025-0.5):1; the mass concentration of dopamine in the aqueous solution of dopamine hydrochloride is 1-3%. 6. the preparation method of a kind of nitrogen-enriched hollow hybrid carbon catalytic material according to claim 1, is characterized in that, the volume ratio of the aqueous solution of solution І, solution II and dopamine hydrochloride is (1～2):1: (0.5～1). 7. A method for preparing a nitrogen-enriched hollow hybrid carbon catalytic material according to claim 1, wherein the inert gas flow rate is 200-500 mL/min; The temperature is raised to the carbonization temperature; the inert atmosphere is N ₂ , Ar or He. 8. A nitrogen-enriched hollow hybrid carbon catalytic material prepared according to any one of claims 1-7, characterized in that the material is in the shape of a monodisperse hollow rounded cube with a particle size ranging from 200 to 400 nm, the nitrogen content is 20-30%, and the specific surface area is 1000-1500 m ² /g. 9. The application of the nitrogen-enriched hollow hybrid carbon catalytic material prepared by the method according to any one of claims 1-7 in low-temperature plasma catalytic oxidation of volatile organic compounds.

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