Plasma synergistic Pt-Mn2O3 catalyst, preparation method thereof and application of plasma synergistic Pt-Mn2O3 catalyst in removal of dichloromethane gas

Abstract

The invention discloses a plasma synergistic Pt-Mn2O3 catalyst, a preparation method of the plasma synergistic Pt-Mn2O3 catalyst and application of the plasma synergistic Pt-Mn2O3 catalyst to removal of dichloromethane gas, and relates to the technical field of gas purification. The invention relates to a plasma synergistic Pt-Mn2O3 catalyst. The plasma synergistic Pt-Mn2O3 catalyst comprises a Mn2O3 carrier and Pt nanoparticles uniformly embedded in the surface of the Mn2O3 carrier, wherein the Mn2O3 carrier has a three-dimensional ordered macroporous structure, and a plurality of oxygen vacancies and defect sites are distributed on the surface of the Mn2O3 carrier. According to the method, the catalytic activity of the Pt-Mn2O3 catalyst is improved through a plasma treatment technology, oxygen vacancies and defect sites are increased, the adsorption capacity of dichloromethane is remarkably improved, and the T90 temperature is reduced by 10-30 DEG C; meanwhile, the 3DOM structure can effectively inhibit high-temperature sintering of Pt particles, and 95% or above of catalytic activity is kept; the surface oxygen species distribution can be optimized by adjusting the plasma discharge time and power, so that the catalyst adapts to the treatment of dichloromethane gases with different concentrations and flow rates.

Description

Technical Field

[0001] The present invention relates to the technical field of gas purification, and in particular to a plasma-enhanced Pt-Mn2O3 catalyst, a preparation method thereof, and application thereof in removing dichloromethane gas. Background Art

[0002] Dichloromethane, a highly toxic and corrosive gas produced in industrial processes such as petrochemicals, natural gas extraction, and wastewater treatment, has long been a challenge in gas purification. While traditional catalytic oxidation methods can effectively remove dichloromethane, they suffer from significant drawbacks such as catalyst deactivation and insufficient low-temperature activity, resulting in low treatment efficiency at low temperatures in practical applications.

[0003] In the existing technology, although Pt-based catalysts have become a research hotspot due to their high low-temperature activity, they are prone to Pt particle sintering under high temperature or complex gas environments, that is, the phenomenon of particle agglomeration and growth under high temperature or specific conditions, which leads to a significant decrease in catalytic efficiency and seriously restricts their industrial application.

[0004] At the same time, although plasma technology can improve the activity by modifying the surface properties of catalysts, the synergistic mechanism between plasma and catalysts is still unclear, resulting in a lack of systematic guidance for the optimization of process parameters, further hindering the development and application of efficient treatment technologies.

[0005] Therefore, the inventors believe that how to solve the problem of low dichloromethane removal efficiency caused by the easy sintering of existing Pt-based catalysts in high temperature or complex environments, the insufficient low-temperature activity of traditional catalysts, and the difficulty in optimizing process parameters due to the unclear synergistic mechanism between plasma and catalyst are technical problems that need to be urgently solved by general technicians in this field.

[0006] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0007] In response to the above technical problems, the embodiments of the present invention provide a plasma-enhanced Pt-Mn2O3 catalyst, a preparation method thereof, and an application in removing dichloromethane gas to solve the problems raised in the above background technology.

[0008] 1. The design principles of the plasma-enhanced Pt-Mn2O3 catalyst, its preparation method, and its application in removing dichloromethane gas are as follows:

[0009] (1) Structural innovation of three-dimensional ordered macroporous (3DOM) carriers

[0010] The 3DOM Mn2O3 carrier was prepared by the template method. Its high specific surface area and regular pore structure were used to provide a spatial confining skeleton for Pt nanoparticles, which physically inhibited the migration and agglomeration of Pt at high temperatures, solving the problem of easy sintering of existing Pt-based catalysts.

[0011] The through-pores of the 3DOM structure not only improve the catalyst's adsorption capacity for dichloromethane, but also optimize the catalytic reaction path by enhancing mass transfer efficiency, so that the catalyst's activity retention rate remains above 95% after high-temperature calcination.

[0012] 2. Activity Control of Plasma Surface Modification

[0013] Through low-temperature plasma (NPC) discharge treatment, the oxygen vacancy concentration on the catalyst surface was precisely controlled. Experiments showed that plasma treatment for 30 minutes could increase the oxygen vacancy concentration to 2.73 (EPR value), significantly enhancing the adsorption and dissociation ability of dichloromethane, and reducing the T 90 The temperature is reduced by 10-30℃, solving the problem of insufficient low-temperature activity of traditional catalysts.

[0014] The high-energy particles generated by the plasma induce Mn2O3 lattice distortion, forming more active defect sites, which synergistically promote redox cycles with Pt nanoparticles and increase CO2 selectivity to 80%.

[0015] 3. Systematic Construction of Plasma-Catalyst Synergistic Mechanism

[0016] A correlation model between plasma discharge time, power and oxygen species distribution on the catalyst surface was established. Through verification through EPR and catalytic performance tests, it was found that 30min / 300W / 50Pa was the optimal processing parameter, which achieved quantitative optimization of process adaptability and broke through the bottleneck of unclear synergistic mechanism in existing technologies.

[0017] The structural stability of the 3DOM carrier, the catalytic activity of Pt and the surface modification effect of plasma are combined to form an integrated technical solution of "structural stability - activity enhancement - parameter adjustment", which is suitable for 10-5000ppm dichloromethane concentration and 10,000-100,000mL·g -1 Wide range of industrial demands for h-1 airspeed.

[0018] 2. A plasma-enhanced Pt-Mn2O3 catalyst comprising: a Mn2O3 carrier and Pt nanoparticles uniformly embedded on the surface of the Mn2O3 carrier;

[0019] Among them, the Mn2O3 carrier has a three-dimensional ordered macroporous structure, and several oxygen vacancies and defect sites are distributed on its surface.

[0020] Preferably, the Pt particle size is controlled to be 1.5-2.0 nm, and the mass of the Pt nanoparticles is 0.2-2.3% of the total mass of the catalyst.

[0021] Preferably, the specific surface area of ​​the Mn2O3 carrier is greater than 3000m 2 / g, and the pore size distribution is 100-500nm.

[0022] A method for producing the plasma-enhanced Pt-Mn2O3 catalyst according to the above-mentioned method comprises the following steps:

[0023] A template method was used to prepare a Mn2O3 support with a three-dimensional ordered macroporous structure;

[0024] Pt nanoparticles were uniformly embedded on the surface of the Mn2O3 support by impregnation to prepare the Pt-Mn2O3 precursor catalyst.

[0025] The Pt-Mn2O3 precursor catalyst was subjected to discharge treatment to prepare the Pt-Mn2O3 catalyst.

[0026] The discharge treatment operation is carried out in a low-temperature plasma reactor.

[0027] Preferably, the step of preparing a Mn2O3 carrier having a three-dimensional ordered macroporous structure by a template method specifically comprises: mixing a manganous nitrate solution with a polymethyl methacrylate microsphere template, and calcining to obtain a Mn2O3 carrier having a three-dimensional ordered macroporous structure.

[0028] Preferably, in the step of discharging the Pt-Mn2O3 precursor catalyst, the discharge parameters meet the following requirements: power is 10-500W; the gas atmosphere is selected from one of air, nitrogen or argon; and the pressure is 10Pa-100Pa.

[0029] Preferably, in the step of performing discharge treatment on the Pt-Mn2O3 precursor catalyst, the discharge time is 0-120 min.

[0030] Preferably, in the step of discharging the Pt-Mn2O3 precursor catalyst, the discharge time is 30 min; the power is 300 W; and the pressure is 50 Pa.

[0031] An application of the plasma-enhanced Pt-Mn2O3 catalyst described above in removing dichloromethane.

[0032] Preferably, the method for removing dichloromethane comprises:

[0033] Place the Pt-Mn2O3 catalyst in a fixed bed reactor and control the reaction temperature between 20-500°C;

[0034] A gas containing dichloromethane is introduced, and the gas composition satisfies: a dichloromethane concentration of 100-5000ppm; a space velocity of 10,000-100,000mL·g -1 ·h-1.

[0035] Preferably, the space velocity is 30,000 mL·g -1 ·h-1.

[0036] The plasma-enhanced Pt-Mn2O3 catalyst provided in the embodiments of the present invention, its preparation method, and its application in removing dichloromethane gas have the following beneficial effects:

[0037] (1) Improved catalytic activity: Plasma treatment creates oxygen vacancies and defect sites on the surface of the Pt-Mn2O3 catalyst, which enhances the adsorption capacity of dichloromethane. 90 Reduce the temperature by 10℃ to 30℃.

[0038] (2) Enhanced anti-sintering performance: The 3DOM structure effectively inhibits the migration and agglomeration of Pt particles at high temperatures. After high-temperature calcination, the catalyst activity retention rate reaches more than 95%.

[0039] (3) Wide process adaptability: By regulating the plasma discharge time and power, the distribution of oxygen species on the catalyst surface can be optimized to meet the treatment requirements of dichloromethane gas with different concentrations and flow rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A working system for the efficient removal of dichloromethane gas using plasma-enhanced Pt-Mn2O3 catalyst.

[0041] Figure 2 The dichloromethane conversion results of Examples 1-3 and Comparative Example 4 are shown.

[0042] Figure 3 These are the selectivity results of CO2 during the dichloromethane conversion process of Examples 1-3 and Comparative Example 4.

[0043] Figure 4 These are the EPR test results of Examples 1-3 and Comparative Example 4. DETAILED DESCRIPTION

[0044] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0045] In response to the above technical problems, the embodiments of the present invention provide a plasma-enhanced Pt-Mn2O3 catalyst, a preparation method thereof, and an application in removing dichloromethane gas to solve the problems raised in the above background technology.

[0046] 1. Preparation of different catalysts

[0047] Example 1:

[0048] (1) Manganous nitrate solution was mixed with polymethyl methacrylate microsphere template and calcined to prepare 3DOM Mn2O3 carrier.

[0049] (2) The Pt precursor (chloroplatinic acid) was loaded on the support surface by the equal volume impregnation method, and a 1 wt% Pt-Mn2O3 catalyst was prepared after ethylene glycol reduction.

[0050] (3) In an NPC reactor, nitrogen was used as the working gas and the catalyst was subjected to a 10-min discharge treatment to obtain a 1 wt% Pt-Mn2O3-10 min catalyst (power: 300 W, pressure: 50 Pa).

[0051] (4) The plasma-treated catalyst was loaded into a fixed bed reactor and a gas containing 800 ppm of dichloromethane (space velocity: 30,000 mL·g -1 ·h-1).

[0052] (5) A dichloromethane catalytic test was conducted on the 1wt% Pt-Mn2O3-10min catalyst at a reaction temperature of 25-500°C.

[0053] Example 2:

[0054] (1) Manganous nitrate solution was mixed with polymethyl methacrylate microsphere template and calcined to prepare 3DOM Mn2O3 carrier.

[0055] (2) The Pt precursor (chloroplatinic acid) was loaded on the support surface by the equal volume impregnation method, and a 1 wt% Pt-Mn2O3 catalyst was prepared after ethylene glycol reduction.

[0056] (3) In an NPC reactor, nitrogen was used as the working gas and the catalyst was subjected to a 30-min discharge treatment to obtain a 1 wt% Pt-Mn2O3-30 min catalyst (power: 300 W, pressure: 50 Pa).

[0057] (4) The plasma-treated catalyst was loaded into a fixed bed reactor and a gas containing 800 ppm of dichloromethane (space velocity: 30,000 mL·g -1 ·h-1).

[0058] (5) A dichloromethane catalytic test was conducted on the 1wt% Pt-Mn2O3-30min catalyst at a reaction temperature of 25-500°C.

[0059] Example 3:

[0060] (1) Manganous nitrate solution was mixed with polymethyl methacrylate microsphere template and calcined to prepare 3DOM Mn2O3 carrier.

[0061] (2) The Pt precursor (chloroplatinic acid) was loaded on the support surface by the equal volume impregnation method, and a 1 wt% Pt-Mn2O3 catalyst was prepared after ethylene glycol reduction.

[0062] (3) In an NPC reactor, nitrogen was used as the working gas and the catalyst was subjected to a 60 min discharge treatment to obtain a 1 wt% Pt-Mn2O3-60 min catalyst (power: 300 W, pressure: 50 Pa).

[0063] (4) The plasma-treated catalyst was loaded into a fixed bed reactor and a gas containing 800 ppm of dichloromethane (space velocity: 30,000 mL·g -1 ·h-1).

[0064] (5) A dichloromethane catalytic test was conducted on the 1wt% Pt-Mn2O3-60min catalyst at a reaction temperature of 25-500°C.

[0065] Comparative Example 4:

[0066] (1) Manganous nitrate solution was mixed with polymethyl methacrylate microsphere template and calcined to prepare 3DOM Mn2O3 carrier.

[0067] (2) The Pt precursor (chloroplatinic acid) was loaded on the support surface by the equal volume impregnation method, and a 1 wt% Pt-Mn2O3 catalyst was prepared after ethylene glycol reduction.

[0068] (3) The catalyst that had not been treated with plasma was loaded into a fixed bed reactor and a gas containing 800 ppm of dichloromethane (space velocity: 30,000 mL·g -1 ·h-1).

[0069] (5) A dichloromethane catalytic test was conducted on 1 wt% Pt-Mn2O3 catalyst at a reaction temperature of 25-500°C.

[0070] 2. Performance Test of Different Catalysts

[0071] The performance of Examples 1-3 and the comparative example is shown in Table 1.

[0072] Table 1: Dichloromethane catalytic performance and oxygen vacancy content of Examples 1-3 and Comparative Example 4

[0073]

[0074] Combine Figure 2-Figure 4 , and the data analysis in Table 1, the comparative analysis of the dichloromethane catalytic performance and oxygen vacancy concentration of Examples 1-3 and Comparative Example 4 shows that plasma discharge treatment is the core factor in improving catalyst performance.

[0075] Compared with Comparative Example 4, the T 90 The results show that plasma treatment can indeed reduce T 90 The temperature decreases and T 90 The temperature data decreased from 10°C to 30°C, reflecting the improvement of catalyst performance by plasma treatment.

[0076] After plasma pretreatment for 30 min, the oxygen vacancy concentration of Example 2 increased significantly (2.73), and its T 50 (340℃) and T 90 (400℃) is the lowest, and the CO2 selectivity reaches 80%, indicating that plasma enhances the low-temperature activity and reaction selectivity of the catalyst by introducing oxygen vacancies; these results show that the process parameters of Example 2 are the optimal parameters.

[0077] The oxygen vacancy concentration of Example 3 (2.24) is similar to that of Example 1 (2.15), but the plasma treatment optimizes its catalytic efficiency. The oxygen vacancy concentration of Comparative Example 4 without plasma treatment is the lowest (1.85), resulting in T 50 / T 90 The highest and the worst CO2 selectivity.

[0078] The study further demonstrated that plasma discharge significantly improved the dichloromethane oxidation performance of the Pt-Mn2O3 catalyst by regulating the oxygen vacancy concentration. The plasma treatment parameters of Example 2 were the optimal process conditions, providing a theoretical basis for industrial application.

[0079] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A plasma enhanced Pt-Mn2O3 catalyst, characterized in that: include: A Mn2O3 carrier and Pt nanoparticles uniformly embedded on the surface of the Mn2O3 carrier; wherein the Mn2O3 carrier has a three-dimensional ordered macroporous structure, and a plurality of oxygen vacancies and defect sites are distributed on its surface.

2. The plasma-enhanced Pt-Mn2O3 catalyst according to claim 1, characterized in that: The Pt particle size is controlled to be 1.5-2.0 nm, and the mass of the Pt nanoparticles is 0.2-2.3% of the total mass of the catalyst.

3. The plasma-enhanced Pt-Mn2O3 catalyst according to claim 1, characterized in that The specific surface area of ​​Mn2O3 carrier is greater than 3000m 2 / g, and the pore size distribution is 100-500nm.

4. A method for producing a plasma-enhanced Pt-Mn2O3 catalyst according to claim 1, characterized in that: The following steps are involved: A template method was used to prepare a Mn2O3 support with a three-dimensional ordered macroporous structure; Pt nanoparticles were uniformly embedded on the surface of the Mn2O3 support by impregnation to prepare the Pt-Mn2O3 precursor catalyst. The Pt-Mn2O3 precursor catalyst was subjected to discharge treatment to prepare the Pt-Mn2O3 catalyst.

5. The method for producing a plasma-enhanced Pt-Mn2O3 catalyst according to claim 3, wherein: The steps of preparing a Mn2O3 carrier with a three-dimensional ordered macroporous structure by a template method specifically include: mixing a manganous nitrate solution with a polymethyl methacrylate microsphere template, and calcining to obtain a Mn2O3 carrier with a three-dimensional ordered macroporous structure.

6. The method for producing a plasma-enhanced Pt-Mn2O3 catalyst according to claim 3, wherein: In the step of discharging the Pt-Mn2O3 precursor catalyst, the discharge parameters meet the following requirements: power is 10-500W; the gas atmosphere is selected from one of air, nitrogen or argon; and the pressure is 10Pa-100Pa.

7. The method for producing a plasma-enhanced Pt-Mn2O3 catalyst according to claim 3, wherein: In the step of discharging the Pt-Mn2O3 precursor catalyst, the discharge time is 0-120 minutes.

8. The method for producing a plasma-enhanced Pt-Mn2O3 catalyst according to claim 3, wherein: In the step of discharging the Pt-Mn2O3 precursor catalyst, the discharge time is 30 minutes, the power is 300W, and the pressure is 50Pa.

9. Use of the plasma-enhanced Pt-Mn2O3 catalyst according to claim 1 in removing dichloromethane, characterized in that: Methods for removing dichloromethane include: Place the Pt-Mn2O3 catalyst in a fixed bed reactor and control the reaction temperature between 20-500°C; A gas containing dichloromethane is introduced, and the gas composition satisfies: a dichloromethane concentration of 100-5000ppm; a space velocity of 10,000-100,000mL·g -1 ·h-1.

10. Use of the plasma-enhanced Pt-Mn2O3 catalyst in removing dichloromethane according to claim 9, characterized in that: Space velocity is 30,000 mL·g -1 ·h-1.

Images