A manganese-based catalyst, its preparation method and application

Abstract

This invention provides a manganese-based catalyst, its preparation method, and its applications. The manganese-based catalyst of this invention comprises a manganese-based active phase and an alkaline earth metal oxide. The alkaline earth metal oxide can not only activate the lattice oxygen of the manganese-based active phase through electron-donating effects, thereby regulating the catalytic combustion activity of the catalyst, but also act as a chlorine acceptor site, thereby regulating the catalyst's resistance to chlorine poisoning. Specifically, the SmMn2O5-SrO catalyst, formed by the coupling of alkaline earth metal oxide SrO and the manganese-based active phase SmMn2O5, maintained a 100% chlorobenzene conversion rate without decrease after 100 hours of chlorobenzene catalytic combustion testing at 195°C. The catalyst provided by this invention exhibits superior catalytic combustion performance compared to traditional manganese-based catalysts. Furthermore, its preparation process is simple, convenient, and low-cost, with high conversion rates of chlorine-containing volatile organic compounds and strong resistance to poisoning and water, demonstrating significant industrial application value.

Description

Technical Field

[0001] This invention relates to the field of catalyst material preparation technology, and in particular to a manganese-based catalyst, its preparation method, and its application. Background Technology

[0002] Catalytic combustion is currently one of the most common methods for eliminating chlorinated volatile organic compounds (VOCs) in industry, avoiding the release of VOCs into the atmosphere and offering advantages such as high conversion efficiency, no pollution, and low operating temperature. Therefore, catalysts for the combustion of VOCs have received widespread attention from industry and academia. Manganese-based catalysts are effective materials for the complete oxidation of VOCs at low temperatures. Currently, to optimize the activity of manganese-based catalysts, numerous attempts have been made to adjust particle size, metal composition, and the metal-support interface, which have improved the activity of manganese-based catalysts in the catalytic combustion of VOCs to some extent. However, compared with improving catalytic activity, developing highly stable manganese-based catalysts remains quite challenging. For VOCs, catalytic combustion leads to the accumulation of chlorinated species on the active sites of the catalyst, which not only easily poisons the catalyst but also provides Lewis acid active sites for electrophilic chlorination reactions, thereby promoting the formation of polychlorinated toxic byproducts. Therefore, avoiding the accumulation of chlorine on the active sites of the catalyst is key to improving catalyst stability and preventing secondary pollution. Therefore, it is necessary to provide a new catalyst that avoids catalyst occurrence poisoning. Summary of the Invention

[0003] In view of this, the present invention provides a manganese-based catalyst, its preparation method and application, to overcome the defects existing in the prior art.

[0004] In a first aspect, the present invention provides a manganese-based catalyst comprising a manganese-based active phase and an alkaline earth metal oxide.

[0005] Preferably, the manganese-based catalyst comprises at least one of SmMn2O5, YMn2O5, CoMn2O4, MnO2, Mn2O3, and Mn3O4 as the manganese-based active phase.

[0006] Preferably, the manganese-based catalyst comprises at least one of MgO, CaO, SrO, and BaO.

[0007] Preferably, the manganese-based catalyst contains 10-90% by mass of alkaline earth metal oxides.

[0008] Secondly, the present invention also provides a method for preparing the manganese-based catalyst, comprising the following steps:

[0009] A mixture is obtained by mixing a manganese-based active phase and an alkaline earth metal oxide.

[0010] The mixture was calcined to obtain a manganese-based catalyst.

[0011] Preferably, the method for preparing the manganese-based catalyst involves mixing the manganese-based active phase and the alkaline earth metal oxide and then ball milling them to obtain a mixture; wherein the ball milling process parameters are: ball milling speed of 100-800 r / min and ball milling time of 10-300 min.

[0012] Preferably, the preparation method of the manganese-based catalyst has the following calcination process parameters: calcination temperature of 300-800℃ and calcination time of 2-4h.

[0013] Thirdly, the present invention also provides the application of the manganese-based catalyst described above or the manganese-based catalyst prepared by the preparation method described above in the catalytic combustion reaction of chlorine-containing volatile organic compounds.

[0014] Preferably, in the aforementioned application, the combustion reaction temperature of the chlorine-containing volatile organic compound is 150–300°C.

[0015] Preferably, in the application, the chlorine-containing volatile organic compound includes at least one of chlorobenzene, carbon tetrachloride, and dichloromethane.

[0016] The present invention has the following advantages over the prior art:

[0017] 1. To further improve the performance of manganese-based catalysts, this invention couples a manganese-based active phase with one or more alkaline earth metal oxides. The electron-donating effect of the alkaline earth metal oxides activates the lattice oxygen of the manganese-based active phase, enhancing the low-temperature catalytic combustion activity of the catalyst. This allows chlorine-containing volatile organic compounds to be completely degraded below the formation temperature of highly toxic byproducts. Furthermore, the strong adsorption capacity of alkaline earth metal oxides for chlorine prevents the accumulation of chlorine-containing species at active sites, thus avoiding catalyst poisoning and improving its stability in the catalytic combustion reaction of chlorine-containing volatile organic compounds.

[0018] 2. This invention prepares a manganese-based catalyst by coupling one or more alkaline earth metal oxides with one or more manganese-based active phases. The obtained catalyst exhibits high catalytic activity over a wide temperature range. For example, the SmMn2O5-SrO catalyst achieves 100% chlorobenzene conversion at 195℃, and its performance shows no decline after 100 hours of stability testing. The catalyst provided by this invention has a better purification effect than traditional manganese-based catalysts, and its preparation process is simple, convenient, low-cost, has a high conversion rate of chlorinated volatile organic compounds, and strong operational stability, making it of significant industrial application value. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The conversion rates of chlorobenzene catalyzed by the manganese-based catalysts in Examples 1-3 at different temperatures;

[0021] Figure 2 The graph shows the stability of the manganese-based catalyst prepared in Example 1 during the catalytic combustion of chlorobenzene at 195°C.

[0022] Figure 3 The graph shows the stability of the manganese-based catalyst prepared in Example 2 during the catalytic combustion of chlorobenzene at 250°C.

[0023] Figure 4 The conversion rate of carbon tetrachloride catalyzed by the manganese-based catalyst in Example 2 at different temperatures;

[0024] Figure 5 The conversion rate of dichloromethane catalyzed by the manganese-based catalyst in Example 2 at different temperatures is shown. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0027] This application provides a manganese-based catalyst, comprising a manganese-based active phase and an alkaline earth metal oxide.

[0028] In some embodiments, the manganese-based active phase includes at least one of SmMn2O5, YMn2O5, CoMn2O4, MnO2, Mn2O3, and Mn3O4.

[0029] In some embodiments, the alkaline earth metal oxide includes at least one of MgO, CaO, SrO, and BaO.

[0030] To further improve the performance of manganese-based catalysts, this invention couples a manganese-based active phase with one or more alkaline earth metal oxides. These alkaline earth metal oxides not only activate the lattice oxygen of the manganese-based active phase through electron-donating effects, thereby regulating the catalyst's catalytic combustion activity, but also act as chlorine acceptor sites, thus regulating the catalyst's resistance to chlorine poisoning. The electron-donating effect of the alkaline earth metal oxides activates the lattice oxygen of the manganese-based active phase, enhancing the catalyst's low-temperature catalytic combustion activity, ensuring the complete degradation of chlorine-containing volatile organic compounds below the formation temperature of highly toxic byproducts. Furthermore, the strong adsorption capacity of alkaline earth metal oxides for chlorine prevents the accumulation of chlorine-containing species at active sites, thus avoiding catalyst poisoning and improving its stability in the catalytic combustion reaction of chlorine-containing volatile organic compounds.

[0031] Specifically, the aforementioned SmMn2O5 is a samarium manganese mullite oxide.

[0032] In some embodiments, the mass fraction of alkaline earth metal oxides in the manganese-based catalyst is 10–90%.

[0033] In some embodiments, the alkaline earth metal oxide is 1 to 3 times the mass of the manganese-based active phase.

[0034] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned manganese-based catalyst, comprising the following steps:

[0035] S1. Mix the manganese-based active phase and the alkaline earth metal oxide to obtain a mixture;

[0036] S2. The mixture is calcined to obtain a manganese-based catalyst.

[0037] In some embodiments, the manganese-based active phase and alkaline earth metal oxide are mixed and then ball-milled to obtain a mixture; wherein the ball milling process parameters are: ball milling speed of 100-800 r / min and ball milling time of 10-300 min.

[0038] In some embodiments, the calcination process parameters are: calcination temperature of 300-800℃ and calcination time of 2-4h.

[0039] This invention prepares a manganese-based catalyst by coupling one or more alkaline earth metal oxides with one or more manganese-based active phases. The obtained catalyst exhibits high catalytic activity over a wide temperature range. For example, the SmMn2O5-SrO catalyst achieves 100% chlorobenzene conversion at 195℃, and its performance shows no decline after 100 hours of stability testing. The catalyst provided by this invention has a superior purification effect compared to traditional manganese-based catalysts. Furthermore, its preparation process is simple, easy to operate, low in cost, and exhibits high conversion rate of chlorinated volatile organic compounds and strong operational stability, demonstrating significant industrial application value.

[0040] Based on the same inventive concept, the present invention also provides the application of the above-mentioned manganese-based catalyst or the manganese-based catalyst prepared by the above-mentioned preparation method in the catalytic combustion reaction of chlorine-containing volatile organic compounds.

[0041] The manganese-based catalyst of this invention is used for the catalytic combustion reaction of chlorine-containing volatile organic compounds. It can be in particulate form or as a coating supported on a honeycomb carrier such as cordierite to prepare a monolithic porous catalyst. The manganese-based catalyst prepared by this invention has good catalytic activity and resistance to chlorine poisoning. It can achieve complete catalytic oxidation of chlorine-containing volatile organic compounds at temperatures below 250°C and maintain long-term stability.

[0042] In some embodiments, the combustion reaction temperature of the chlorine-containing volatile organic compounds described above is 150–300°C.

[0043] In some embodiments, the chlorine-containing volatile organic compounds described above include at least one of chlorobenzene, carbon tetrachloride, and dichloromethane.

[0044] Preferably, the catalytic combustion temperature of chlorobenzene is 200°C.

[0045] The following specific embodiments further illustrate the manganese-based catalyst of this application, its preparation method, and its application. This section further illustrates the content of the present invention with reference to specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0046] Example 1

[0047] This application provides a method for preparing a manganese-based catalyst, comprising the following steps:

[0048] S1. Mix SrO powder and SmMn2O5 powder at a mass ratio of 2:1, and then ball mill at 200 r / min for 10 min to obtain SmMn2O5-SrO mixture;

[0049] S2. The SmMn2O5-SrO mixture in S1 is calcined at 500℃ for 3h to obtain the SmMn2O5-SrO catalyst, which is a manganese-based catalyst.

[0050] Example 2

[0051] This application provides a method for preparing a manganese-based catalyst, comprising the following steps:

[0052] S1. CaO powder and SmMn2O5 powder are mixed at a mass ratio of 2:1 and then ball-milled at 200 r / min for 10 min to obtain a SmMn2O5-CaO mixture.

[0053] S2. The SmMn2O5-CaO mixture in S1 is calcined at 500℃ for 3 hours to obtain the SmMn2O5-SrO catalyst, which is a manganese-based catalyst.

[0054] Example 3

[0055] This application provides a method for preparing a manganese-based catalyst, comprising the following steps:

[0056] S1. Mix SrO powder and Mn2O3 powder at a mass ratio of 2:1, and then ball mill at 200 r / min for 10 min to obtain Mn2O3-SrO mixture;

[0057] S2. The Mn2O3-SrO mixture in S1 is calcined at 500℃ for 3 hours to obtain the Mn2O3-SrO catalyst, which is a manganese-based catalyst.

[0058] Catalytic performance test

[0059] The catalytic activity of the manganese-based catalysts prepared in Examples 1-3 was tested.

[0060] Specifically, the catalytic activity (catalytic combustion of p-chlorobenzene) of the manganese-based catalysts prepared in Examples 1-3 was tested in a fixed-bed reactor. The manganese-based catalyst was loaded with 0.3 g of material, with a particle size of 40-60 mesh. The initial gas concentrations were: chlorobenzene 100 ppm, oxygen 10 vol%, nitrogen as the carrier gas, and a mass hourly space velocity (MSV) of 20000 mL·g. -1 ·h -1 The test temperature was 100–400℃, and the conversion rate of chlorobenzene was tested. The results are as follows: Figure 1 As shown.

[0061] Figure 2 To test the stability of the manganese-based catalyst prepared in Example 1 for the catalytic combustion of chlorobenzene at 195°C, the test method was the same as above, except that the temperature was kept constant at 195°C during the test, and the chlorobenzene conversion rate was tested over time.

[0062] Figure 3 To test the stability of the manganese-based catalyst prepared in Example 2 for the catalytic combustion of chlorobenzene at 250°C, the test method was the same as above, except that the temperature was kept constant at 250°C during the test, and the chlorobenzene conversion rate was tested over time.

[0063] from Figure 1 It can be seen that the manganese-based catalysts prepared in Examples 1 to 3 can all achieve complete catalytic oxidation of chlorobenzene at temperatures below 300°C.

[0064] from Figure 2 and Figure 3 It can be seen that the manganese-based catalysts prepared in Examples 1 and 2 have excellent resistance to chlorine poisoning.

[0065] Further testing of the catalytic activity (catalytic combustion of carbon tetrachloride) of the manganese-based catalyst prepared in Example 2 was conducted in a fixed-bed reactor. The manganese-based catalyst was loaded with 0.3 g of material, with a particle size of 40–60 mesh. The initial gas concentrations were: carbon tetrachloride 100 ppm, oxygen 10 vol%, nitrogen as the carrier gas, and a mass hourly space velocity (HSV) of 20,000 mL·g. -1 ·h -1 The test temperature was 100–400℃, and the conversion rate of carbon tetrachloride was tested. The results are as follows: Figure 4 As shown.

[0066] Further testing of the catalytic activity (catalytic combustion of dichloromethane) of the manganese-based catalyst prepared in Example 2 was conducted in a fixed-bed reactor. The manganese-based catalyst was loaded with 0.3 g of material, with a particle size of 40–60 mesh. The initial gas concentrations were: dichloromethane 100 ppm, oxygen 10 vol%, nitrogen as the carrier gas, and a mass hourly space velocity (HSV) of 20,000 mL·g. -1 ·h -1 The test temperature was 100–400℃, and the conversion rate of dichloromethane was tested. The results are as follows: Figure 5 As shown.

[0067] from Figure 4 and Figure 5 It can be seen that the manganese-based catalyst prepared in Example 2 has excellent versatility and can achieve complete catalytic oxidation of a variety of chlorine-containing volatile organic compounds at temperatures below 300°C.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. The application of a manganese-based catalyst in the catalytic combustion reaction of chlorine-containing volatile organic compounds; The method for preparing the manganese-based catalyst includes the following steps: A mixture is obtained by mixing a manganese-based active phase and an alkaline earth metal oxide. The mixture was calcined to obtain a manganese-based catalyst; The manganese-based active phase is SmMn2O5, and the alkaline earth metal oxide is SrO; Alternatively, the manganese-based active phase may be Mn2O3, and the alkaline earth metal oxide may be SrO.

2. The application as described in claim 1, characterized in that, The manganese-based active phase and alkaline earth metal oxide were mixed and ball-milled to obtain a mixture; the ball milling process parameters were: ball milling speed of 100-800 r / min and ball milling time of 10-300 min.

3. The application as described in claim 1, characterized in that, The calcination process parameters are: calcination temperature of 300~800℃ and calcination time of 2~4h.

4. The application as described in claim 1, characterized in that, The combustion reaction temperature of the chlorine-containing volatile organic compounds is 150~300℃.

5. The application as described in claim 1, characterized in that, The chlorine-containing volatile organic compounds include at least one of chlorobenzene, carbon tetrachloride, and dichloromethane.

6. The application as described in claim 1, characterized in that, The mass of alkaline earth metal oxides is twice that of the manganese-based active phase.

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