Monatomic manganese / graphdiyne catalyst, preparation method thereof and application of monatomic manganese / graphdiyne catalyst in catalytic ozonation toluene degradation

Abstract

The invention discloses a monatomic manganese / graphdiyne catalyst, a preparation method thereof and application of the monatomic manganese / graphdiyne catalyst in catalytic ozonation degradation of toluene, and belongs to the technical field of materials. The application of the monatomic manganese / graphdiyne catalyst in catalytic degradation of ozonized toluene comprises the following steps: putting the monatomic manganese / graphdiyne catalyst into a reaction tube, and introducing oxygen, nitrogen and toluene into the reaction tube. The preparation method of the monatomic manganese / graphdiyne catalyst comprises the following steps: dispersing graphdiyne powder in a first solvent to obtain a solution A; dispersing soluble manganese salt into a second solvent to obtain a solution B; mixing the solution A and the solution B to obtain dispersion liquid C; and drying the C dispersion liquid to obtain the monatomic manganese / graphdiyne catalyst. The monatomic manganese / graphdiyne catalyst provided by the invention is used for catalyzing ozone toluene, and shows 100% toluene catalytic decomposition activity and 100-hour catalytic stability under the conditions of room temperature and high humidity (RH = 30%).

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a single-atom manganese / graphene catalyst and a preparation method thereof, and application thereof in catalytic ozonation degradation of toluene. Background Art

[0002] Volatile organic compounds, commonly referred to as VOCs, are usually divided into several categories, such as non-methane hydrocarbons (NMHCs for short), oxygen-containing organic compounds, halogenated hydrocarbons, nitrogen-containing organic compounds, and sulfur-containing organic compounds. In recent years, many pollutant control technologies have been developed: such as thermal oxidation, non-thermal plasma, photocatalytic oxidation, and catalytic combustion. Among them, catalytic combustion is one of the most widely used technologies. However, the processing temperature of industrial catalytic combustion usually needs to be completed under the conditions of 500-800°C, which greatly increases the energy consumption and economic cost of the catalytic combustion process; the catalyst is also easily deactivated due to high-temperature sintering; the high-temperature catalytic process also brings greater safety risks to industrial production. Therefore, traditional industrial VOCs treatment technology can no longer meet the needs of green and sustainable development of enterprises and society. There are many types of VOCs involved in the actual industrial application process, but there are not many catalysts with good room temperature degradation effect for toluene in the industrial automobile spraying process, and the catalyst surface is more susceptible to water poisoning and deactivation at room temperature. Therefore, how to achieve catalytic decomposition of toluene at room temperature and high humidity (humidity 30%-90%) is a technical problem that the existing technology needs to solve. Summary of the invention

[0003] The purpose of the present invention is to overcome the above technical deficiencies, provide a single-atom manganese / graphene catalyst and a preparation method thereof and use thereof in catalytic ozonation degradation of toluene, and solve the technical problem of how to achieve catalytic decomposition of toluene at room temperature and high humidity in the prior art.

[0004] In order to achieve the above technical objectives, the technical solution of the present invention provides an application of a single-atom manganese / graphene catalyst in catalytic ozonation degradation of toluene.

[0005] In any embodiment, the above application includes placing a single-atom manganese / graphene catalyst in a reaction tube, and introducing oxygen, nitrogen and toluene into the reaction tube.

[0006] In any embodiment, the flow rate of oxygen is 30-35 mL / min, the flow rate of nitrogen balance gas is 35-40 mL / min, and the flow rate of toluene gas is 30-35 mL / min.

[0007] In any embodiment, the reaction temperature of the catalytic degradation is 20-30°C.

[0008] In addition, the present invention also provides a method for preparing a manganese graphyne catalyst, comprising the following steps:

[0009] Dispersing graphyne in a first solvent to obtain a solution A;

[0010] dispersing a soluble manganese salt in a second solvent to obtain a solution B;

[0011] Mixing solution A and solution B to obtain dispersion C;

[0012] The C dispersion is dried to obtain a manganese graphyne catalyst.

[0013] In any embodiment, the A solution and the B solution are mixed in a mass ratio of graphyne to soluble manganese salt of (3-5):(1-3) to obtain a C dispersion.

[0014] In any embodiment, the mass concentration of graphyne in the A solution is 3-5 mg / mL, and the mass concentration of soluble manganese salt in the B solution is 2-3 mg / mL.

[0015] In any embodiment, the first solvent or the second solvent is one of methanol, ethanol, ammonia water and water; and / or the soluble manganese salt is one or more of manganese nitrate, manganese chloride, manganese acetate or their respective corresponding hydrates.

[0016] In any embodiment, dispersing graphyne in a first solvent to obtain solution A comprises: mixing graphyne and the first solvent, and then ultrasonically obtaining solution A.

[0017] In any embodiment, dispersing the soluble manganese salt in the second solvent to obtain solution B includes: mixing the soluble manganese salt and the second solvent, and then ultrasonically obtaining the solution B; and / or, mixing solution A and solution B to obtain dispersion C includes: dropping solution B into solution A, and then stirring for 1.5-2.5 hours to obtain dispersion C; and / or, the temperature for drying the dispersion C is 50-60°C, and the drying time is more than 12 hours.

[0018] The present invention achieves atomic-level monodispersion of metallic manganese on the carrier graphyne through the strategy of loading metal atoms by dropwise addition method and low-temperature drying, thereby successfully avoiding the agglomeration of metallic manganese on the surface of the prepared graphyne-based catalyst.

[0019] Compared with the prior art, the beneficial effects of the present invention include: application of a single-atom manganese / graphene catalyst in catalytic ozonation degradation of toluene, the catalyst is an atomically dispersed catalyst, the catalyst can effectively decompose toluene, and exhibits 100% catalytic activity and 100 hours of stability at room temperature (25°C) and high humidity (humidity 30%-90%). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1This is a scanning electron microscope image of the single-atom manganese / graphene catalyst prepared in Example 1 of the present invention.

[0021] Figure 2 This is the XRD pattern of the single-atom manganese / graphene catalyst prepared in Example 1 of the present invention.

[0022] Figure 3 This is the Raman graph of the single-atom manganese / graphene catalyst prepared in Example 1 of the present invention.

[0023] Figure 4 This is the XPS spectrum of the single-atom manganese / graphene catalyst prepared in Example 1 of the present invention.

[0024] Figure 5 This is an activity curve diagram of the catalytic ozonation decomposition of toluene by the single-atom manganese / graphene catalyst prepared in Example 1 of the present invention.

[0025] Figure 6 This is a 100h stability test chart of the single-atom manganese / graphene catalyst prepared in Example 1 of the present invention.

[0026] Figure 7 This is a statistical chart of carbon balance data for the ozonation decomposition of toluene catalyzed by the single-atom manganese / graphene catalyst prepared in Example 1 of the present invention.

[0027] Figure 8 This is a comparison chart of the activity curves of the single-atom manganese / graphene catalyst prepared in Example 1 of the present invention for catalytic ozonation of toluene under the condition of humidity RH=0-90%.

[0028] Fig. 9 This is a comparison chart of the activity curves of catalytic ozonation of toluene by manganese-based catalysts of other carbon material carrier comparison samples and commercial manganese oxide catalysts prepared in Example 1 of the present invention.

[0029] Fig.10 The activity curves of the single-atom copper / graphene catalyst and the single-atom iron / graphene catalyst for catalytic ozonation of toluene are shown in Figure 1.

[0030] Fig.11 The temperature-programmed activity curves of the comparative samples single-atom copper / graphene catalyst and single-atom iron / graphene catalyst prepared in Example 1 of the present invention for catalytic oxidation of toluene are shown.

[0031] Fig.12 This is an activity curve of catalytic ozonation of toluene by the diatomic copper cobalt / graphene catalyst of the comparative sample prepared in Example 1 of the present invention.

[0032] Fig.13 This is an activity curve of the comparative sample diatomic copper cobalt graphyne catalyst prepared in Example 1 of the present invention for catalytic ozonation of ethyl acetate.

[0033] Fig.14 This is a comparison chart of the superoxide radical intensity signals of the single-atom manganese / graphite catalyst, nanoparticle manganese / graphite, and graphite catalyst prepared in Example 1 of the present invention.

[0034] Fig.15 This is a comparison chart of the hydroxyl radical intensity signals of the single-atom manganese / graphite catalyst, nanoparticle manganese / graphite, and graphite catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0036] If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0037] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0038] This specific embodiment provides a method for preparing a manganese graphyne catalyst, comprising the following steps:

[0039] Dispersing graphyne in a first solvent to obtain a solution A; the mass concentration of graphyne in the solution A is 3-5 mg / mL;

[0040] Dispersing a soluble manganese salt in a second solvent to obtain a solution B; the mass concentration of the soluble manganese salt in the solution B is 2-3 mg / mL; the first solvent or the second solvent is one of methanol, ethanol, ammonia water and water; the soluble manganese salt is one or more of manganese nitrate, manganese chloride, manganese acetate or their respective corresponding hydrates;

[0041] The A solution and the B solution are mixed in a mass ratio of graphyne to soluble manganese salt of (3-5):(2-3) to obtain a C dispersion;

[0042] The C dispersion is dried to obtain a manganese graphyne catalyst; the C dispersion is dried at a temperature of 50-60° C. and the drying time is more than 12 hours.

[0043] In some embodiments, dispersing graphyne in a first solvent to obtain solution A comprises: mixing graphyne and the first solvent, and then ultrasonically obtaining solution A.

[0044] In some embodiments, dispersing the soluble manganese salt in the second solvent to obtain the B solution comprises: mixing the soluble manganese salt and the second solvent, and then ultrasonicating to obtain the B solution.

[0045] In some embodiments, the mixing of solution A and solution B to obtain dispersion C comprises: adding solution B dropwise to solution A, followed by stirring for 1.5-2.5 hours to obtain dispersion C.

[0046] This specific embodiment also provides a manganese graphyne catalyst, which is prepared by the above preparation method.

[0047] This specific embodiment also proposes a manganese graphyne catalyst prepared by the above preparation method or the use of the above manganese graphyne catalyst in catalytic degradation of ozonated toluene, including placing a manganese graphyne catalyst in a reaction tube, and introducing oxygen, nitrogen and toluene into the reaction tube; the oxygen flow rate is 30-35mL / min, ozone is generated by an ozone generator with a concentration of 700ppm, the nitrogen balance gas flow rate is 35-40mL / min, the toluene gas flow rate is 30-35mL / min, and the toluene gas concentration after mixing is 100ppm; the temperature of the catalytic degradation is 20-30°C.

[0048] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0049] In the present invention, reference is made to “some embodiments”, “this embodiment”, examples, etc., which describe a subset of all possible embodiments, but it can be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0050] If similar descriptions of "first / second" appear in the application documents, the following instructions are added. In the following description, the terms "first\second\third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged in a specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0051] In this embodiment, the term "and / or" is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, object A and / or object B may represent three situations: object A exists alone, object A and object B exist at the same time, and object B exists alone.

[0052] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0053] The methanol solution in the following examples is pure methanol, using analytical grade reagents with a purity of 99%.

[0054] Example 1

[0055] This embodiment provides a single-atom manganese / graphene catalyst, which is prepared by the following steps:

[0056] 130 mg of gypsum powder was weighed and added to beaker A. A stirring bar was added to beaker A. Then 20 mL of methanol solution was measured with a measuring cylinder and added to beaker A. The gypsum powder was evenly dispersed under ultrasonic conditions for 5 min to obtain solution A.

[0057] Then transfer to a magnetic stirrer and stir at room temperature at 600 rpm for later use; weigh 30.0 mg of manganese nitrate (Mn(NO3)2) tetrahydrate using a 1 / 10,000 analytical balance and quickly add it to beaker B; then use a measuring cylinder to measure 10 mL of methanol solution and add it to the above beaker B; evenly disperse under ultrasonic conditions for 5 minutes to obtain a manganese nitrate methanol B solution of a certain concentration;

[0058] Subsequently, the manganese nitrate methanol solution B is added dropwise into the A solution using a rubber-tipped dropper or a syringe pump under stirring, and the reaction is fully stirred for 2 hours at room temperature to obtain a C dispersion. At this time, the metallic manganese has been successfully loaded on the graphyne carrier; the magnetic stirrer is removed, and the C dispersion is transferred to an oven and dried at a constant temperature of 60°C for 12 hours. After the methanol solvent is completely evaporated, a dry single-atom manganese graphyne-based catalyst sample is obtained, and the sample color is black (named: SA Mn / Graphdiyne).

[0059] For the prepared single atom manganese / graphene-based catalyst samples (SA Mn / Graphdiyne), the following Figure 1-4 The catalyst structure and morphology are characterized. Figure 1 The scanning electron microscope image shows that the prepared single-atom manganese / graphene-based catalyst sample is blocky and has no clear morphology. Figure 2 From the XRD pattern, it can be seen that there is no characteristic peak of Mn metal, and the metal manganese in the surface catalyst is atomically monodispersed, proving that the atomically dispersed manganese / graphene catalyst was successfully prepared; Figure 3 The Raman spectrum also further confirmed that the manganese atoms in the catalyst were monodispersed and the graphyne structure was not changed; Figure 4 The XPS spectrum shows that the manganese atoms on the surface of the catalyst exist in the form of divalent manganese atoms, which further proves that the manganese metal is successfully loaded on the graphyne carrier.

[0060] Example 2

[0061] This embodiment provides a single-atom manganese / graphene catalyst, which is prepared by the following steps:

[0062] 130 mg of gypsum powder was weighed and added to beaker A. A stirring bar was added to beaker A. Then 20 mL of methanol solution was measured with a measuring cylinder and added to beaker A. The gypsum powder was evenly dispersed under ultrasonic conditions for 5 min to obtain solution A.

[0063] Then transfer to a magnetic stirrer and stir at room temperature at 700 rpm for later use; weigh 26.0 mg of manganese nitrate (Mn(NO3)2) tetrahydrate using a 1 / 10,000 analytical balance and quickly add it to beaker B; then use a measuring cylinder to measure 10 mL of methanol solution and add it to the above beaker B; evenly disperse under ultrasonic conditions for 5 minutes to obtain a manganese nitrate methanol B solution of a certain concentration;

[0064] Subsequently, the manganese nitrate methanol solution B is added dropwise into the A solution using a rubber-tipped dropper or a syringe pump under stirring, and the reaction is fully stirred for 1.5 hours at room temperature to obtain a C dispersion. At this time, the metallic manganese has been successfully loaded on the graphyne carrier; the magnetic stirrer is removed, and the C dispersion is transferred to an oven and dried at a constant temperature of 55°C for 13 hours. After the methanol solvent is completely evaporated, a dry single-atom manganese / graphyne-based catalyst sample is obtained.

[0065] Example 3

[0066] This embodiment provides a single atom / manganese graphyne catalyst, which is prepared by the following steps:

[0067] 130 mg of gypsum powder was weighed and added to beaker A. A stirring bar was added to beaker A. Then 20 mL of methanol solution was measured with a measuring cylinder and added to beaker A. The gypsum powder was evenly dispersed under ultrasonic conditions for 5 min to obtain solution A.

[0068] Then transfer to a magnetic stirrer and stir at room temperature at 500 rpm for later use; weigh 78.0 mg of manganese nitrate (Mn(NO3)2) tetrahydrate using a 1 / 10,000 analytical balance and quickly add it to beaker B; then use a measuring cylinder to measure 10 mL of methanol solution and add it to the above beaker B; evenly disperse under ultrasonic conditions for 5 minutes to obtain a manganese nitrate methanol B solution of a certain concentration;

[0069] Subsequently, the manganese nitrate methanol solution B is added dropwise into the A solution using a rubber-tipped dropper or a syringe pump under stirring, and the reaction is fully stirred for 2 hours at room temperature to obtain a C dispersion. At this time, the metallic manganese has been successfully loaded on the graphyne carrier; the magnetic stirrer is removed, and the C dispersion is transferred to an oven and dried at a constant temperature of 50°C for 14 hours. After the methanol solvent is completely evaporated, a dry single-atom manganese / graphyne-based catalyst sample is obtained.

[0070] Example 4

[0071] This embodiment provides a manganese graphyne catalyst, which is prepared by the following steps:

[0072] Weigh 120 mg of gypsum powder and add it to beaker A. Add a stirrer to beaker A. Then use a measuring cylinder to measure 20 mL of methanol solution and add it to beaker A. Ultrasonicate for 5 min to evenly disperse the gypsum powder to obtain solution A.

[0073] Then transfer to a magnetic stirrer and stir at room temperature at 800 rpm for later use; use a 1 / 10,000 analytical balance to weigh 30.0 mg of manganese chloride and quickly add it to beaker B; then use a measuring cylinder to measure 10 mL of methanol solution and add it to the beaker B; uniformly disperse under ultrasonic conditions for 5 minutes to obtain a manganese nitrate methanol B solution of a certain concentration;

[0074] Subsequently, the manganese nitrate methanol solution B is added dropwise into the A solution using a rubber-tipped dropper or a syringe pump under stirring, and the reaction is fully stirred for 2.5 hours at room temperature to obtain a C dispersion. At this time, the metallic manganese has been successfully loaded on the graphyne carrier; the magnetic stirrer is removed, and the C dispersion is transferred to an oven and dried at a constant temperature of 60°C for 12 hours. After the methanol solvent is completely evaporated, a dry single-atom manganese / graphyne-based catalyst sample is obtained.

[0075] In order to further verify the advantages of single-atom manganese / graphdiyne catalysts in the field of VOCs degradation, we applied the single-atom manganese / graphdiyne-based catalyst prepared in Example 1 to the room temperature catalytic ozonation decomposition activity test of toluene; at the same time, nanoparticle manganese / graphdiyne (named: NP Mn / Graphdiyne) and pure graphdiyne were subjected to the same test for easy comparison.

[0076] The preparation method of the nanoparticle manganese / graphdiyne sample (NP Mn / Graphdiyne) is as follows: first, commercial nanoparticle manganese oxide (MnO2) is weighed according to a certain mass ratio and added into a container, and then a certain amount of graphdiyne catalyst is weighed and added to ensure that the mass ratio of Mn:graphdiyne is 5:100. After mechanical grinding for 20 minutes to mix evenly, the nanoparticle manganese / graphdiyne sample (NP Mn / Graphdiyne) uniformly dispersed on the surface of graphdiyne is obtained.

[0077] The selected test conditions are: the test gas is toluene, the concentration of the mixed gas cylinder is 300ppm. In a quartz tube glass reactor with an inner diameter of 6mm and an outer diameter of 8mm, 100mg of the above catalyst sample is loaded, the total gas flow rate is controlled to 100mL / min, and the volumetric space velocity is 60,000mL g -1 h -1 , where the oxygen flow rate is 30mL / min, the ozone concentration generated by the ozone generator is 700ppm, the N2 as the balance gas flow rate is 36.7mL / min, the toluene gas flow rate is 33.3mL / min, the toluene concentration after mixing is 100ppm, and the reaction test humidity is 30%. The toluene concentration in the tail gas is detected and analyzed by gas chromatography, and the ozone concentration is detected by an ozone detector. The reaction temperature during the test is room temperature (25°C) and the humidity is 30%.

[0078] The catalyst stability test conditions are consistent with the above-mentioned activity test conditions, except that the test time is extended to 100 hours.

[0079] The results are as follows Figure 5 and Figure 6 As shown, from Figure 5From the comparison of the activity curves of different catalysts, it can be seen that the single-atom manganese / graphene catalyst prepared in Example 1 exhibits 100% toluene catalytic ozonation activity at room temperature; Figure 6 From the catalyst stability test results shown, it can be seen that the single-atom manganese / graphene catalyst prepared in Example 1 shows good stability and can still maintain 100% toluene decomposition activity after 100 hours of catalytic test. The toluene catalytic activity of the comparison sample nanoparticle manganese / graphene decreased by 60% after 24 hours of activity test, while the toluene catalytic activity of pure graphene at room temperature is almost 0.

[0080] from Figure 7 The test results show that after toluene is oxidized, it is converted into CO2 and CO in a ratio of about 5:1, while after the nanoparticles / graphene catalyzes the decomposition of toluene, the ratio of CO2 and CO converted is about 1:1, with significantly less CO2 produced, further proving that single-atom manganese / graphene has better room-temperature toluene catalytic activity.

[0081] Further change the reaction test humidity, other test conditions remain the same as the above test, humidity RH = 30-90%, such as Figure 8 , the decomposition activity of single-atom manganese / graphene catalyzed ozonation of toluene at room temperature can be maintained at 100% conversion rate within 12 hours. However, when the humidity is 0%, the catalytic ozonation decomposition activity of toluene will rapidly drop to about 25% within 12 hours. Therefore, compared with the low humidity test conditions (humidity RH = 0%), it is further proved that the single-atom manganese / graphene catalyst has excellent performance in catalyzing the ozonation of toluene under high humidity (humidity RH = 30-90%), successfully solving the problem of catalyst deactivation in water under high humidity, and broadening its application in actual industrial VOCs treatment.

[0082] The test method for the catalytic performance of the catalyst used for comparison in the following description is also the same as the test method for the room temperature catalytic ozone decomposition activity of the catalyst in Example 1 above.

[0083] The preparation of the following comparative examples of activated carbon-supported manganese (Mn / Active carbon), carbon nanotube-supported manganese (Mn / CNT), and manganese / graphene (Mn / Graphene) is similar to the preparation method of single-atom manganese / hydrogenated graphene in Example 1, except that the carrier graphene is replaced. Fig. 9The test results show that other carbon material supported catalysts, such as manganese / carbon nanotubes (Mn / CNT), manganese / activated carbon (Mn / Active carbon), and manganese / graphene (Mn / Graphe ne), all showed worse toluene conversion rates, with conversion rates of 70%, 39%, and 52%, respectively. At the same time, compared with other commercial manganese oxide catalysts, the toluene conversion rate of manganese dioxide catalyst (coml.MnO2) dropped to 30% after 12 hours, while the manganese oxide catalyst (coml.MnO) was completely deactivated within 1 hour, with a toluene conversion rate of 0%. The same preparation method was further adopted, except that the metal manganese salt manganese nitrate was replaced by the metal copper salt copper nitrate and the metal iron salt iron nitrate, to prepare single-atom copper / graphene (named: SA Cu / Graphdiyne) and single-atom iron / graphene catalyst (named: SA Fe / G raphdiyne), and their activity test results are as follows: Fig.10 As shown, after 10 hours, the toluene decomposition activity of single-atom copper / graphene and single-atom iron / graphene catalysts both dropped to 10%, and the catalytic performance was significantly lower than that of single-atom manganese / graphene. Fig.11 The single-atom copper / gdyne and single-atom iron / gdyne catalysts were further tested for their high-temperature catalytic ozonation toluene decomposition activity by programmed temperature increase. The test results showed that the single-atom copper / gdyne temperature had to reach about 145°C to achieve complete conversion of toluene, while the single-atom iron / gdyne catalyst had to reach 165°C to achieve 100% toluene removal efficiency, demonstrating the low-temperature superiority of the single-atom manganese / gdyne catalyst in catalyzing the ozonation toluene decomposition of the present invention. Fig.12 , and compared with the diatomic copper cobalt / graphdiyne catalyst (CuCo / Graphdiyne), wherein the synthesis method of the diatomic catalyst is prepared by reference to Example 1 of the preparation method of the diatomic copper cobalt / graphdiyne catalyst in patent application number: 202310192712.7. The results show that whether the test humidity is 0% or 30%, the diatomic copper cobalt / graphdiyne catalyst has a room temperature catalytic ozonation toluene decomposition activity that will rapidly drop to 0%. Fig.13 The room temperature catalytic ozonation decomposition activity of ethyl acetate by the diatomic copper cobalt / graphene catalyst was further tested. The results showed that the room temperature catalytic ozonation decomposition activity of ethyl acetate was 10% under the condition of 30% humidity. When the test humidity was changed to 0%, the ethyl acetate decomposition activity was relatively good, and the conversion rate could be maintained at about 40%. Therefore, it was shown that the activation and resistance of the diatomic copper cobalt / graphene catalyst to water were significantly worse than those of the single atomic manganese / graphene catalyst in the present invention. The diatomic copper cobalt / graphene catalyst showed worse catalytic activity under the test conditions with water. Further, as Fig.14 and 15The free radical capture experiment (electron paramagnetic resonance) was used to test the types and intensities of free radicals generated during the ozonation reaction catalyzed by single-atom manganese / graphene, nanoparticle manganese / graphene and graphene catalyst. The results showed that compared with pure graphene and nanoparticle / graphene catalyst, single-atom manganese / graphene catalyst can significantly produce stronger superoxide free radicals (·O2 - ) and hydroxyl radical (·OH) signals. This further shows that the single-atom manganese / graphene catalyst can activate ozone to produce more active oxygen species during the reaction compared with other catalysts, promoting the room temperature catalytic ozone decomposition activity.

[0084] The catalysts prepared in Examples 2-4 have catalytic performance comparable to that of the catalyst prepared in Example 1.

[0085] Other beneficial effects:

[0086] 1. The present invention efficiently synthesizes atomically dispersed single-atom manganese / graphene catalysts through a simple impregnation method. The method is simple and efficient and can be applied to industrial large-scale preparation in the future.

[0087] 2. The present invention successfully applies the atomically dispersed single-atom manganese / graphite catalyst to the room temperature catalytic ozonation toluene decomposition, showing 100% catalytic activity and 100h stability under the condition of room temperature humidity RH=30%. Even under the condition of 90% humidity, the single-atom manganese / graphite catalyst can still maintain 100% room temperature toluene decomposition performance. This catalytic performance far exceeds the best performance reported in literature and patents.

[0088] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. Application of single-atom manganese / graphene catalyst in catalytic ozonation degradation of toluene.

2. The use according to claim 1, characterized in that: The method comprises placing a single-atom manganese / graphene catalyst in a reaction tube, and introducing oxygen, nitrogen and toluene into the reaction tube.

3. The use according to claim 2, characterized in that: The flow rate of oxygen is 30-35 mL / min, the flow rate of nitrogen balance gas is 35-40 mL / min, and the flow rate of toluene gas is 30-35 mL / min.

4. The use according to claim 1, characterized in that: The reaction temperature of the catalytic degradation is 20-30°C.

5. A method for preparing a single-atom manganese / graphene catalyst, characterized in that: The following steps are involved: Dispersing graphyne in a first solvent to obtain a solution A; dispersing a soluble manganese salt in a second solvent to obtain a solution B; Mixing solution A and solution B to obtain dispersion C; The C dispersion is dried to obtain a single-atom manganese / graphene catalyst.

6. The method for preparing the single-atom manganese / graphene catalyst according to claim 5, characterized in that: The A solution and the B solution are mixed in a mass ratio of graphyne to soluble manganese salt of (3-5):(1-3) to obtain a C dispersion.

7. The method for preparing the single-atom manganese / graphene catalyst according to claim 5, characterized in that: The mass concentration of graphyne in the solution A is 3-5 mg / mL, and the mass concentration of soluble manganese salt in the solution B is 2-3 mg / mL.

8. The method for preparing the single-atom manganese / graphene catalyst according to claim 5, characterized in that: The first solvent or the second solvent is one of methanol, ethanol, ammonia water and water; and / or the soluble manganese salt is one or more of manganese nitrate, manganese chloride, manganese acetate or their respective corresponding hydrates.

9. The method for preparing the single-atom manganese / graphene catalyst according to claim 5, characterized in that: The step of dispersing graphyne in a first solvent to obtain a solution A comprises: mixing graphyne and the first solvent, and then performing ultrasonic treatment to obtain the solution A.

10. The method for preparing the single-atom manganese / graphene catalyst according to claim 5, characterized in that: The method of dispersing the soluble manganese salt in the second solvent to obtain the B solution includes: mixing the soluble manganese salt and the second solvent, and then ultrasonically obtaining the B solution; and / or, the method of mixing the A solution and the B solution to obtain the C dispersion includes: dropping the B solution into the A solution, and then stirring for 1.5-2.5 hours to obtain the C dispersion; and / or, the C dispersion is dried at a temperature of 50-60°C and a drying time of more than 12 hours.

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