Manganese-based catalyst as well as preparation method and application thereof

Abstract

The invention provides a manganese-based catalyst and application thereof, the manganese-based catalyst comprises pseudo-boehmite and an active component loaded on the pseudo-boehmite; the pseudo-boehmite is of an ordered cluster structure, and the surface of the pseudo-boehmite has hydroxyl; the active component is loaded on surface wrinkles or pore channels of the pseudo-boehmite, and the active component comprises manganese oxide. Pseudo-boehmite with the surface rich in hydroxyl serves as an aluminum source to synthesize a manganese-based material, the synergistic effect with plasma is enhanced, generation of free radicals and oxidation valence cycle of manganese are promoted, the catalytic activity is kept, adsorption of a synergistic system to chlorobenzene can be enhanced, the retention time of chlorobenzene in a reaction system is greatly prolonged, and the catalytic activity of chlorobenzene is improved. Therefore, the degradation efficiency of chlorobenzene is improved, and the generation of ozone and nitrogen oxides is inhibited.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic material preparation, and in particular relates to a manganese-based catalyst and application thereof. Background Art

[0002] In secondary nonferrous metal smelting, incomplete combustion products of fuels, such as chlorobenzene, can act as precursors to form dioxins (PCDD / Fs). Both dioxins and chlorobenzene are highly toxic, with the most toxic dioxin being 1,000 times more toxic than potassium cyanide (KCN), earning it the nickname "the most toxic poison on Earth."

[0003] At present, the main technologies for controlling the terminal chlorobenzene in smelting flue gas include activated carbon adsorption technology and catalytic oxidation technology. However, neither activated carbon adsorption technology nor catalytic technology can achieve efficient removal of chlorobenzene in low-temperature flue gas (flue gas temperature is often between 130°C and 160°C). The high-energy electrons and active free radical groups generated by plasma discharge can quickly convert VOCs molecules at room temperature and pressure, but the plasma degradation process is prone to produce intermediate toxic products such as ozone and nitrogen oxides, which can easily cause secondary pollution. In comparison, plasma synergistic catalytic technology can improve carbon dioxide selectivity and inhibit the formation of reaction by-products, but studies have found that due to the size of the plasma discharge area and the residence time of chlorobenzene in the system, the degradation rate of chlorobenzene is significantly lower than that of other organic matter in the flue gas. Summary of the Invention

[0004] Aiming to solve the technical problem of low chlorobenzene degradation rate in the above conventional technologies, the present invention provides a manganese-based catalyst comprising pseudo-boehmite and an active component supported thereon;

[0005] The pseudo-boehmite has an ordered cluster structure and has hydroxyl groups on its surface; the active component is loaded on the surface wrinkles or pores of the pseudo-boehmite, and the active component includes manganese oxide.

[0006] Furthermore, in terms of mass fraction, the mass proportion of manganese in the manganese-based catalyst is 1% to 20%, and the Mn in the manganese-based catalyst is 4+ With Mn 3+ The molar ratio is 31.51~52.41.

[0007] Furthermore, the specific surface area of the manganese-based catalyst is 184.3 to 219.5 m 2 / g, pore volume is 0.41~0.44cm 3 / g, and the average pore diameter is 8.0-8.6nm.

[0008] Furthermore, the adsorbed oxygen in the manganese-based catalyst accounts for 50.79% to 66.36% of the total amount of adsorbed oxygen and lattice oxygen.

[0009] Furthermore, the content of the characteristic peak of the weak acid site of the manganese-based catalyst is 0.8-0.9 mmol / g, and the content of the characteristic peak of the strong acid site is 1.9-2.0 mmol / g.

[0010] The present invention provides a method for preparing a manganese-based catalyst, comprising the steps of:

[0011] A manganese source reagent is mixed with the pseudo-boehmite slurry, and stirred at a temperature of 80 to 90° C. for 1.5 to 2.5 hours to obtain a mixed slurry; the manganese source in the manganese source reagent includes manganese acetate tetrahydrate, and the mass ratio of the manganese source to the pseudo-boehmite is 0.0445 g / 1.1647 g to 0.8909 g / 0.9412 g;

[0012] The mixed slurry is sequentially subjected to aging treatment, drying treatment and calcination treatment to obtain the manganese-based catalyst.

[0013] Furthermore, the temperature of the aging treatment is 10-40°C, the temperature of the drying treatment is 60-100°C, and the temperature of the calcination treatment is 500-600°C.

[0014] The present invention provides use of any one of the above manganese-based catalysts in the treatment of chlorobenzene.

[0015] Further, the steps include:

[0016] The chlorobenzene-containing flue gas is contacted with the manganese-based catalyst after plasma enhancement, and the chlorobenzene in the chlorobenzene-containing flue gas is converted into carbon dioxide and other organic matter through a catalytic oxidation reaction; wherein the temperature of the catalytic oxidation reaction is 10-40°C, and the space velocity of the catalytic oxidation reaction is 4000-12000h -1 .

[0017] Furthermore, during the plasma strengthening process, the discharge input voltage is set to 16-24VA, and the discharge current is set to 1.38A-1.59A.

[0018] Compared with the prior art, the present invention has at least the following advantages:

[0019] The present invention provides a manganese-based catalyst that can be combined with plasma technology for chlorobenzene treatment: the plasma technology synergistically promotes the generation of free radicals and the oxidation valence state cycle of manganese, so that the manganese-based catalyst maintains high activity during the catalytic oxidation reaction of chlorobenzene, significantly improving the chlorobenzene degradation efficiency; at the same time, compared with other carrier materials, the pore structure of the manganese-based catalyst with pseudo-boehmite as the carrier is significantly improved and the specific surface area is increased. Combined with the adsorption capacity of chlorobenzene by the rich hydroxyl groups on the surface of pseudo-boehmite, the manganese-based catalyst has improved capture and anchoring capabilities for chlorobenzene, which greatly increases the residence time of chlorobenzene in the reaction system and further optimizes the degradation effect of chlorobenzene. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0021] Figure 1(a) is a SEM image of PB in Analysis Example 1 of the present invention, Figure 1(b) is a SEM image of Mn-PB in Analysis Example 1 of the present invention, and Figure 1(c) is a SEM image of Mn-Al2O3 prepared in Analysis Example 1 of the present invention.

[0022] Figure 2 This is a bar chart of the chlorobenzene reaction efficiency corresponding to the single plasma system, plasma-assisted Mn-Al2O3 system, and plasma-assisted Mn-PB system in Analysis Example 2 of the present invention.

[0023] Figure 3 This is a curve diagram of the catalytic activity of the plasma system alone, the plasma-coordinated Mn-Al2O3 system, and the plasma-coordinated Mn-PB system as the voltage changes in Analysis Example 2 of the present invention.

[0024] Figure 4 This is a curve diagram showing the change of chlorobenzene catalytic combustion activity with voltage under different space velocity conditions in Analysis Example 3 of the present invention.

[0025] Figure 5 This is a graph showing the change in chlorobenzene degradation efficiency over time when chlorobenzene is treated by plasma in conjunction with the Mn-PB system in Analysis Example 4 of the present invention.

[0026] Figure 6 This is the NH3-TPD diagram before and after the Mn-PB reaction in Analysis Example 5 of the present invention.

[0027] Figure 7 This is the NH3-TPD diagram of Mn-PB and MnOx-Al2O3 in analysis example 5 of the present invention.

[0028] Figure 8 This is the XPS spectrum of O1s before and after the Mn-PB reaction in Analysis Example 5 of the present invention.

[0029] Figure 9 XPS spectra of O1s of Mn-PB and MnOx-Al2O3 in Example 5 of the present invention.

[0030] Figure 10 The Mn2p before and after the Mn-PB reaction in Example 5 of the present invention is analyzed. 1 / 2 XPS spectrum of . DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0032] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those in the examples of the present invention may also be used to implement the present invention.

[0034] In the smelting of secondary non-ferrous metals, raw materials contain significant amounts of organic impurities. Incomplete combustion of these impurities produces organic matter that reacts with various inorganic substances to form dioxins (PCDD / Fs). Incompletely destroyed PCDD / Fs may also be present in the waste residue of raw materials, releasing them before temperatures reach sufficient levels for their complete decomposition. Incomplete combustion of fuels produces incomplete combustion products, such as chlorobenzene, chlorophenols, and polychlorinated biphenyls (PCBs), which react with these precursors to form PCDD / Fs. Chlorinated organic compounds such as dioxins and chlorobenzene are highly toxic. The most toxic dioxin, chlorobenzene, is 1,000 times more toxic than potassium cyanide (KCN), earning it the nickname "the most toxic poison on Earth." Once released into the environment, these chlorinated organic pollutants pose a significant threat to ecosystems and human health.

[0035] Currently, the main terminal control technologies for CVOCs in smelting flue gas include activated carbon adsorption technology and catalytic oxidation technology.

[0036] The adsorption effect of activated carbon completes the collection of pollutants in the thermal desorption exhaust gas, but does not actually reduce the total amount of pollutants. The generated hazardous waste must be post-processed through complex processes to achieve the purpose of fundamental purification. Although activated carbon adsorption is currently the most widely used exhaust gas purification technology, from an overall and long-term perspective, the use of activated carbon to adsorb chlorine-containing organic pollutants to achieve exhaust gas purification still has major flaws. In addition, in experimental design, only the adsorption of a specific pollutant by activated carbon is often studied, and the moisture and other contents in the actual flue gas have not been considered. In actual incinerators, the exhaust gas may also contain water vapor, heavy metals, etc., which will compete with the pollutants for adsorption.

[0037] Catalytic oxidation technology can degrade CVOCs to produce carbon dioxide, hydrogen chloride, and water, offering low energy consumption, high efficiency, and few secondary pollutants. However, chlorobenzene catalytic degradation technology is expensive to operate and maintain, and some catalysts are susceptible to failure due to the presence of chlorine. Furthermore, commercial catalysts only exhibit significant catalytic activity above 300°C. Within this temperature range, chlorobenzene and chlorophenols in the flue gas are susceptible to heterogeneous synthesis reactions under the catalytic action of metals, posing the risk of dioxin formation. The constant wear and clogging of catalysts by large amounts of fly ash in the flue gas also significantly impacts catalyst life. Therefore, controlling dioxins in the flue gas requires placing the catalytic tower after the bag filter. However, the flue gas temperature after the bag filter is often around 160°C. To achieve catalytic activity, the flue gas temperature must be raised again, a process that consumes significant amounts of steam from the power plant and wastes energy.

[0038] The present invention provides a manganese-based catalyst, comprising pseudo-boehmite and an active component supported thereon;

[0039] The pseudo-boehmite has an ordered cluster structure and has abundant hydroxyl groups on its surface; the active component is uniformly and densely loaded on the surface wrinkles or pores of the pseudo-boehmite, and the active component includes manganese element.

[0040] In the present invention, the manganese element in the manganese-based catalyst accounts for 1% to 20% by mass. In some more specific embodiments, the manganese element in the manganese-based catalyst accounts for 1% to 5% by mass.

[0041] In the present invention, the specific surface area of the manganese-based catalyst is 184.3 to 219.5 m 2 / g, pore volume is 0.41~0.44cm 3 / g, and the average pore diameter is 8.0-8.6nm.

[0042] In the present invention, the adsorbed oxygen in the manganese-based catalyst accounts for 50.79% to 66.36% of the total amount of adsorbed oxygen and lattice oxygen.

[0043] In the present invention, the content of the characteristic peak of the weak acid site of the manganese-based catalyst is 0.8-0.9 mmol / g, and the content of the characteristic peak of the strong acid site is 1.9-2.0 mmol / g.

[0044] Compared with the prior art, the present invention has at least the following advantages:

[0045] The present invention provides a manganese-based catalyst that can be combined with plasma technology for chlorobenzene treatment: the plasma technology synergistically promotes the generation of free radicals and the oxidation valence state cycle of manganese, so that the manganese-based catalyst maintains high activity during the catalytic oxidation reaction of chlorobenzene, significantly improving the chlorobenzene degradation efficiency; at the same time, compared with other carrier materials, the pore structure of the manganese-based catalyst with pseudo-boehmite as the carrier is significantly improved and the specific surface area is increased. Combined with the adsorption capacity of chlorobenzene by the rich hydroxyl groups on the surface of pseudo-boehmite, the manganese-based catalyst has improved capture and anchoring capabilities for chlorobenzene, which greatly increases the residence time of chlorobenzene in the reaction system and further optimizes the degradation effect of chlorobenzene.

[0046] In the plasma reactor, high-voltage electric fields are used to excite gases to generate active species such as high-energy electrons, ions, and free radicals. These active species have strong oxidizing ability and can directly attack the benzene ring or chlorine atom in the chlorobenzene molecule, triggering ring-opening, hydroxylation, or dechlorination reactions.

[0047] Manganese oxide (MnOx) has multiple or mixed valences and is easy to undergo Mn 3+ / Mn 4+The redox cycle, variable electronic structure, high surface lattice oxygen mobility, various tunable crystal phase shapes, and specially exposed planes have led to widespread application in plasma catalysis. The synthesis of manganese-based materials using pseudo-boehmite, a hydroxyl-rich surface, as an aluminum source enhances synergy with the plasma, promoting the generation of free radicals and the cycling of manganese oxidation states, maintaining catalytic activity, and enhancing the adsorption of chlorobenzene by the synergistic system, significantly increasing the residence time of chlorobenzene in the reaction system, thereby improving the degradation efficiency of chlorobenzene and inhibiting the formation of ozone and nitrogen oxides.

[0048] The present invention provides a method for preparing a manganese-based catalyst, comprising the steps of:

[0049] The manganese source reagent is mixed with the pseudo-boehmite slurry, and stirred at a temperature of 80 to 90° C. for 1.5 to 2.5 hours to obtain a mixed slurry.

[0050] In the present invention, the manganese source reagent is a mixture of a manganese source and a solvent, and the manganese source includes manganese acetate tetrahydrate. In some embodiments, the solvent includes deionized water; in some specific embodiments, the preparation of the manganese source reagent may include: dissolving manganese acetate tetrahydrate in deionized water, wherein the mass volume ratio of manganese acetate tetrahydrate to deionized water may be 0.0445 to 0.8909 g / 10 ml. In the present invention, the pseudo-boehmite slurry may be a mixture of pseudo-boehmite and a solvent; in some embodiments, the solvent includes ethanol; in some specific embodiments, the preparation of the pseudo-boehmite slurry may include: adding pseudo-boehmite powder to anhydrous ethanol, wherein the mass volume ratio of pseudo-boehmite to anhydrous ethanol may be 0.9412 to 1.1647 g / 20 ml.

[0051] In the present invention, the mass ratio of the manganese source to the pseudo-boehmite can be 0.0445g / 1.1647g to 0.8909g / 0.9412g;

[0052] The mixed slurry is sequentially subjected to aging treatment, drying treatment and calcination treatment to obtain the manganese-based catalyst.

[0053] In the present invention, the temperature of the aging treatment is 10-40° C., the temperature of the drying treatment is 60-100° C., and the temperature of the calcination treatment is 500-600° C. In some embodiments, the aging treatment can be performed at room temperature.

[0054] In some embodiments, the aging treatment may last for 10 to 14 hours, the drying treatment may last for 10 to 14 hours, and the calcination treatment may last for 2 to 4 hours. The aging treatment may include: aging under ventilation at room temperature.

[0055] In some embodiments, the calcined sample obtained by the calcination process may be passed through a 60-mesh sieve.

[0056] In some specific implementations, the preparation of a manganese-based catalyst may include the following steps: dissolving 0.1339 g of manganese acetate tetrahydrate in 10 ml of deionized water, adding 1.1412 g of pseudo-boehmite powder to 20 ml of anhydrous ethanol, stirring until uniform, then adding the manganese acetate solution while stirring, and heating the mixed solution at 80°C with stirring for 2 hours. Thereafter, the sample is aged at room temperature for 12 hours, dried at 100°C for 12 hours, and then calcined at 550°C for 3 hours. The calcined sample is then passed through a 60-mesh sieve to produce the manganese-based catalyst.

[0057] The present invention also provides a use of any one of the above manganese-based catalysts in the treatment of chlorobenzene.

[0058] In the present invention, a manganese-based catalyst can be combined with plasma technology to be applied to chlorobenzene treatment, comprising the steps of:

[0059] The chlorobenzene-containing flue gas is contacted with the manganese-based catalyst after plasma enhancement, and the chlorobenzene in the chlorobenzene-containing flue gas is converted into carbon dioxide and other organic matter through a catalytic oxidation reaction; wherein the temperature of the catalytic oxidation reaction is 10-40°C, and the space velocity of the catalytic oxidation reaction is 6000-12000h -1 ; The mass ratio of the concentration of chlorobenzene in the chlorobenzene-containing flue gas to the manganese-based catalyst is 150-600 ppm / 0.1-0.3 g.

[0060] In some embodiments, the catalytic oxidation reaction can be performed at room temperature.

[0061] In some embodiments, the space velocity of the catalytic oxidation reaction can be 6000-7000 h -1 .

[0062] In the present invention, the chlorobenzene concentration in the chlorobenzene-containing flue gas may be 150 to 600 ppm. In some embodiments, the chlorobenzene-containing atmosphere may comprise 5% to 20% oxygen by volume, with the remainder being nitrogen. In more specific embodiments, the chlorobenzene-containing atmosphere may comprise 20% oxygen by volume, with the remainder being nitrogen.

[0063] In some embodiments, the flow rate of chlorobenzene-containing flue gas can be 300 mL to 1 L / min.

[0064] In the present invention, the plasma enhanced processing technology can be provided by a plasma reactor; in some embodiments, the plasma reactor can use the CTP-2000 low-temperature plasma experimental power supply of Nanjing Suman Plasma Technology Co., Ltd., with a center frequency of 9.6kHz, an output voltage of 0-30kV, an output frequency range of 5-20kHz, and a maximum output power of 500W.

[0065] In some embodiments, during the plasma enhancement process, the discharge input voltage is set to 16-24VA, and the discharge current is set to 1.38A-1.59A.

[0066] In some embodiments, the plasma-assisted catalyst catalytic degradation system for chlorobenzene may be composed of a gas distribution system, a chlorobenzene generation system, a temperature control system, a plasma reaction system, and a chlorobenzene decomposition product monitoring system.

[0067] In some embodiments, a syringe pump can be used to eject chlorobenzene at a constant rate. Chlorobenzene is rapidly vaporized at 120°C and carried by the reaction gas (20% oxygen, the rest nitrogen) to the plasma-assisted catalyst system for reaction. Chlorobenzene and other intermediates in the reaction exhaust gas are analyzed by GC-MS. The exhaust gas is collected by an air bag, and carbon monoxide and carbon dioxide are detected by chromatography.

[0068] In some embodiments, the degradation efficiency of chlorobenzene is calculated by monitoring the change in the signal value of chlorobenzene in a gas chromatography-mass spectrometer before and after the reaction.

[0069] The present invention provides a manganese-based catalyst prepared by the above-mentioned method for preparing the manganese-based catalyst.

[0070] In order to facilitate those skilled in the art to further understand the present invention, examples are given below:

[0071] Example 1

[0072] Synthesis of manganese-based catalysts

[0073] A pseudo-boehmite-supported MnOx-PB (Mn-PB) with high surface hydroxyl content was prepared by an impregnation method. First, 0.1339 g of manganese acetate tetrahydrate was dissolved in 10 ml of deionized water. 1.1412 g of pseudo-boehmite powder was added to 20 ml of anhydrous ethanol and stirred until uniform. The manganese acetate solution was then added while stirring. The mixture was heated and stirred at 80°C for 2 h. The sample was then aged at room temperature for 12 h, dried at 100°C for 12 h, and calcined at 550°C for 3 h. The sample was passed through a 60-mesh sieve to obtain the manganese-based catalyst, designated Mn-PB.

[0074] Comparative Example 1

[0075] Synthesis of Mn-PB (20% loading)

[0076] A 20%-loaded MnOx-PB (abbreviated as Mn-PB (20% loading)) with a pseudo-boehmite support and rich in surface hydroxyl groups was prepared by an impregnation method. First, 0.8909 g of manganese acetate tetrahydrate was dissolved in 10 ml of deionized water. 0.9412 g of pseudo-boehmite powder was added to 20 ml of anhydrous ethanol and stirred until homogeneous. The manganese acetate solution was then added while stirring. The mixture was heated and stirred at 80°C for 2 h. The sample was then aged at room temperature for 12 h, dried at 100°C for 12 h, and calcined at 550°C for 3 h. The sample was passed through a 60-mesh sieve to obtain the manganese-based catalyst, designated Mn-PB20.

[0077] Comparative Example 2

[0078] Synthesis of catalysts supported on alumina

[0079] Alumina-supported MnOx-Al2O3 (Mn-Al2O3) with high surface hydroxyl content was prepared by an impregnation method. First, 0.1339 g of manganese acetate tetrahydrate was dissolved in 10 ml of deionized water. 0.92 g of alumina powder was added to 20 ml of anhydrous ethanol and stirred until homogenous. The manganese acetate solution was then added while stirring. The mixture was heated and stirred at 80°C for 2 h. The sample was then aged at room temperature for 12 h, dried at 100°C for 12 h, and calcined at 550°C for 3 h. The sample was then passed through a 60-mesh sieve to obtain the alumina-supported catalyst, designated Mn-Al2O3.

[0080] It should be noted that the following Mn-PB was prepared by Example 1 of the present invention, Mn-Al2O3 was prepared by Comparative Example 2 of the present invention, and Mn-PB (20% loading) was prepared by Comparative Example 1 of the present invention.

[0081] Analysis example 1

[0082] BET test was performed on Mn-PB, Mn-Al2O3, Mn-PB (20% loading), and PB (i.e., alumina without active component loading, the same below).

[0083] As shown in Table 1, the specific surface area of Mn-PB is 219.5 m 2 / g, and the specific surface area of PB is much larger than that of Mn-Al2O3, indicating that the loading of a large amount of active components causes the catalyst surface to wrinkle or fill the pores, resulting in a decrease in its specific surface area. A larger specific surface area is conducive to the physical adsorption of pollutants, but it is not the only factor affecting catalytic activity. The specific surface area of the catalyst material with ordinary alumina as the carrier has dropped significantly, which is almost an order of magnitude different from other materials. This shows that the pore structure of the catalyst has changed significantly. It also shows that the use of pseudo-boehmite with rich surface hydroxyl groups as the carrier has significantly improved the pore structure of the catalyst, further proving that a high specific surface area is extremely beneficial for improving the reaction performance of the catalyst.

[0084] Table 1 Pore structure parameters of Mn-PB, Mn-Al2O3, Mn-PB (20% loading), and PB

[0085]

[0086]

[0087] SEM examination of Mn-PB, Mn-Al2O3, Mn-PB (20% loading), and PB

[0088] See Figure 1, in which Figure 1(a) is a SEM image of PB, Figure 1(b) is a SEM image of Mn-PB prepared in Example 1 of the present invention, and Figure 1(c) is a SEM image of Mn-Al2O3 prepared in Comparative Example 2 of the present invention. As can be seen from the figure, the surface of Al2O3 without active component loading has a large number of cavities and a large number of large depressions. The addition of Mn active component makes the catalyst surface denser, and the depressions on the catalyst surface are occupied by active components and appear convex, thereby increasing the number of active centers on the catalyst surface and improving the degradation efficiency of chlorobenzene. In contrast to the disordered free dispersion state of materials with ordinary alumina as the carrier, the material with pseudo-boehmite as the carrier forms a clear cluster structure, and the active components are more evenly and densely loaded on the catalyst surface. This is conducive to increasing the specific surface area of the metal oxide catalyst, improving the system's adsorption capacity for chlorobenzene, and thus improving the reaction performance of the catalyst, which is consistent with the BET data and experimental data.

[0089] Element content analysis of Mn-PB and Mn-Al2O3

[0090] The element content analysis results of Mn-PB and Mn-Al2O3 are shown in Table 1.

[0091]

[0092] As can be seen from Table 1, the manganese content in the material with pseudo-boehmite as the carrier is 1.6%, while in the commercial alumina material, the manganese content is only 0.5%. The analysis results of the crystal structure and surface elements show that manganese is well loaded on the pseudo-boehmite in an amorphous state.

[0093] Example 2

[0094] Application of Mn-PB in Chlorobenzene Treatment

[0095] Chlorobenzene was injected at a constant rate using a syringe pump. Chlorobenzene was rapidly vaporized at 120°C and carried by the reaction gas (20% oxygen, the rest nitrogen) to a plasma-assisted catalyst (the catalyst was a manganese-based catalyst Mn-PB) system for catalytic oxidation. The temperature of the catalytic oxidation reaction was 25°C, and the space velocity of the catalytic oxidation reaction was 4000 h-1. -1 Chlorobenzene and other intermediates in the reaction tail gas were analyzed by GC-MS, while the tail gas was collected by air bag and carbon monoxide and carbon dioxide were detected by chromatography.

[0096] Experimental results: The conditions were set as discharge input voltage 18V, discharge current 1.42A, initial chlorobenzene concentration 300ppm, catalyst dosage 0.2g, and gas flow rate 1L / min. The degradation efficiency of chlorobenzene was calculated by monitoring the change in the signal value of chlorobenzene in the gas chromatography-mass spectrometry before and after the reaction.

[0097] Comparative Example 3

[0098] Compared with Example 2, other conditions remain unchanged, only the Mn-PB in the ionic synergistic catalyst system is replaced by Mn-Al2O3

[0099] Comparative Example 4

[0100] Compared with Example 2, other conditions remain unchanged, only the plasma-coordinated catalyst system is replaced by a single plasma system.

[0101] Analysis example 2

[0102] Analysis of chlorobenzene reaction efficiency in different systems

[0103] See also Figure 2 , Figure 2The following bar charts show the chlorobenzene reaction efficiency for a single plasma system, a plasma-assisted Mn-Al2O3 system, and a plasma-assisted Mn-PB system. In the single plasma system, the chlorobenzene degradation efficiency was approximately 60%. However, in the synergistic system, after loading the plasma reactor with the catalyst material, the chlorobenzene reaction efficiency was significantly improved. Compared to conventional commercial alumina, the material supported by pseudoboehmite exhibited superior catalytic performance, with the chlorobenzene degradation efficiency increasing from 71% to 85%. This suggests that the abundant hydroxyl groups on the pseudoboehmite surface enhance the system's adsorption capacity for chlorobenzene and increase the generation of reactive oxygen species on the material's surface.

[0104] Analyze the catalytic activity of different systems as a function of voltage

[0105] See also Figure 3 , Figure 3 The catalytic activity curves for different systems vary with voltage. Comparing the catalytic activity curves for the plasma-alone system and the synergistic system shows that the catalytic degradation efficiency of chlorobenzene increases with increasing voltage. However, after the discharge voltage reaches 20V, further increases in voltage have little effect on the chlorobenzene degradation efficiency, indicating that the plasma's promoting effect on the reaction has reached saturation at this point, and further increases in voltage will not significantly improve the catalytic activity of chlorobenzene in the system.

[0106] Analysis example 3

[0107] The effect of space velocity on the catalytic combustion of chlorobenzene in plasma-assisted Mn-PB system is analyzed. Figure 4 , Figure 4 The curve of chlorobenzene catalytic combustion activity versus voltage under different space velocity conditions is shown in the figure. As can be seen from the results, with the increase of reaction space velocity, the chlorobenzene catalytic activity shows a trend of first increasing and then decreasing. The increase is because the increase in catalyst increases the residence time of chlorobenzene in the system, while the reason for the decrease in effect may be that too much catalyst changes the discharge parameters of the plasma. At this time, the synergistic effect of the catalyst and plasma is not good. The results show that the space velocity is 6000h -1 When the catalyst and plasma are combined, the best synergistic effect can be achieved.

[0108] Analysis example 4

[0109] Investigating the stability of the chlorobenzene catalytic combustion reaction during the application of Mn-PB in Example 2

[0110] See also Figure 5 , Figure 5 This is a curve showing the change in chlorobenzene degradation efficiency over time when the plasma synergistic Mn-PB system is used to treat chlorobenzene. It can be seen that after loading the manganese-based catalyst, the synergistic system can stably operate for 5.5 hours with a chlorobenzene degradation efficiency of about 85%.

[0111] Analysis example 5

[0112] Acidity analysis

[0113] like Figure 6 As shown, Figure 6 The NH3-TPD patterns before and after the Mn-PB reaction in Example 2 show characteristic peaks at around 100°C and 400°C, respectively, at weakly acidic and strongly acidic sites. These peaks, at concentrations of 0.87 mmol / g and 1.94 mmol / g, indicate strong acidic sites in the pre-reaction sample. These sites may be related to the surface properties of manganese oxide or the hydroxyl groups of pseudo-boehmite. After the reaction, the weak acid content decreased to 0.45 mmol / g, while the strong acid content decreased to 1.11 mmol / g. The desorption peaks significantly weakened and almost disappeared, indicating that the catalyst's acidic sites participated in the decomposition of chlorobenzene. The acid sites of the sample after the reaction were significantly reduced, which may be due to the consumption or coverage of the acid sites during the reaction. This shows that the acid sites play a vital role in the catalytic reaction of chlorobenzene. First, they activate the chlorobenzene molecules through electrostatic adsorption or coordination, reducing the C-Cl bond breaking energy. In addition, the acid sites can capture high-energy electrons in the plasma, promote the dissociation of O2, generate more free radicals, and effectively promote the catalytic reaction of chlorobenzene. At the same time, they can form key intermediates. Figure 7 As shown, the NH3-TPD diagrams of Mn-PB prepared in Example 1 and MnOx-Al2O3 prepared in Comparative Example 2 were analyzed. It can be seen that the desorption peak of MnOx-Al2O3 is weak and almost non-existent, and the surface weak acid sites and strong acid sites are only 0.14mmol / g and 0.44mmol / g, respectively, which are significantly less than those of MnOx-PB. Therefore, the decomposition performance of chlorobenzene is weaker. The surface acidity of the catalyst is improved compared with that of MnOx-Al2O3, indicating that the rich surface hydroxyl groups of the pseudo-boehmite support have a significant contribution to the formation of acid sites on the catalyst surface. The acidity of the material with pseudo-boehmite as the support is improved compared with ordinary alumina. This can also explain the synergy between the material with pseudo-boehmite as the support and the plasma to present a more excellent chlorobenzene conversion efficiency.

[0114] Elemental analysis

[0115] like Figure 8 As shown, Figure 8 The XPS spectra of O1s before and after the Mn-PB reaction in Example 2 of the present invention were analyzed. The XPS spectra of O1s before and after the Mn-PB reaction were compared and found that the proportion of surface adsorbed oxygen decreased significantly after the reaction, indicating that surface adsorbed oxygen (Oads) plays a key role in the catalytic reaction of chlorobenzene; see Figure 9 , Figure 9The O1s XPS spectra of Mn-PB prepared in Example 1 and MnOx-Al2O3 prepared in Comparative Example 2 show that MnOx-PB has a higher amount of surface adsorbed oxygen. Surface adsorbed oxygen can serve as a temporary electron storage site, accepting electrons from active sites or plasma radicals during the chlorobenzene oxidation process to maintain redox equilibrium. The adsorbed oxygen then transfers electrons back to the catalyst, achieving catalyst regeneration. Furthermore, the surface adsorbed oxygen can preferentially bind to chloride ions, reducing their toxic effects on the catalyst's active sites, thereby improving reaction durability. This is consistent with the excellent stability data for chlorobenzene degradation in the synergistic system. Furthermore, the high energy input provided by the plasma also reduces the activation energy of surface adsorbed oxygen, allowing it to efficiently participate in the reaction at low temperatures.

[0116] like Figure 10 As shown, the Mn2p before and after the Mn-PB reaction in Example 2 of the present invention is compared. 1 / 2 XPS spectrum, the tetravalent manganese content decreased after the reaction, Mn 4+ It can directly oxidize chlorobenzene molecules, causing CH bond cleavage and hydroxylation reaction, thereby reducing energy consumption. The high-energy electrons and active free radicals generated by the plasma interact with the manganese sites on the catalyst surface, promoting the 4+ and Mn 3+ The reversible conversion of chlorobenzene can be achieved, thereby promoting the catalytic combustion of chlorobenzene in the system.

[0117] Table 4 Elemental analysis of MnOx-Al2O3 and MnOx-PB before and after reaction in Example 2

[0118]

[0119] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A manganese-based catalyst, characterized in that It includes pseudo-boehmite and active components supported thereon; The pseudo-boehmite has an ordered cluster structure and has hydroxyl groups on its surface; the active component is loaded on the surface wrinkles or pores of the pseudo-boehmite, and the active component includes manganese oxide.

2. The manganese-based catalyst according to claim 1, characterized in that In terms of mass fraction, the mass proportion of manganese in the manganese-based catalyst is 1% to 20%, and the Mn in the manganese-based catalyst is 4+ With Mn 3+ The molar ratio is 31.51~52.

41.

3. The manganese-based catalyst according to claim 1, characterized in that The specific surface area of the manganese-based catalyst is 184.3 to 219.5 m 2 / g, pore volume is 0.41~0.44cm 3 / g, and the average pore diameter is 8.0-8.6nm.

4. The manganese-based catalyst according to claim 1, characterized in that The adsorbed oxygen in the manganese-based catalyst accounts for 50.79% to 66.36% of the total amount of adsorbed oxygen and lattice oxygen.

5. The manganese-based catalyst according to claim 1, characterized in that The content of the characteristic peak of the weak acid site of the manganese-based catalyst is 0.8-0.9 mmol / g, and the content of the characteristic peak of the strong acid site is 1.9-2.0 mmol / g.

6. A method for preparing a manganese-based catalyst, characterized in that: Including steps: A manganese source reagent is mixed with the pseudo-boehmite slurry, and stirred at a temperature of 80 to 90° C. for 1.5 to 2.5 hours to obtain a mixed slurry; the manganese source in the manganese source reagent includes manganese acetate tetrahydrate, and the mass ratio of the manganese source to the pseudo-boehmite is 0.0445 g / 1.1647 g to 0.8909 g / 0.9412 g; The mixed slurry is sequentially subjected to aging treatment, drying treatment and calcination treatment to obtain the manganese-based catalyst.

7. The method for preparing a manganese-based catalyst according to claim 6, wherein: The temperature of the aging treatment is 10-40°C, the temperature of the drying treatment is 60-100°C, and the temperature of the calcination treatment is 500-600°C.

8. Use of the manganese-based catalyst according to any one of claims 1 to 5 in the treatment of chlorobenzene.

9. Use of the manganese-based catalyst in chlorobenzene treatment according to claim 8, characterized in that Including steps: The chlorobenzene-containing flue gas is contacted with the manganese-based catalyst after plasma enhancement, and the chlorobenzene in the chlorobenzene-containing flue gas is converted into carbon dioxide and other organic matter through a catalytic oxidation reaction; wherein the temperature of the catalytic oxidation reaction is 10-40°C, and the space velocity of the catalytic oxidation reaction is 4000-12000h -1 .

10. Use of the manganese-based catalyst in chlorobenzene treatment according to claim 8, characterized in that: During the plasma strengthening process, the discharge input voltage is set to 16-24VA, and the discharge current is set to 1.38A-1.59A.

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