Method for catalytic degradation of trimethylamine by plasma

Abstract

The application discloses a method for plasmonic catalytic degradation of trimethylamine, comprising the following steps: adding MnO2@LaO x The catalyst is filled into a discharge bed layer area of a plasma reactor to perform plasmonic catalytic degradation of trimethylamine; the MnO2@LaO x The catalyst comprises a nanorod-shaped MnO2 carrier and lanthanum oxide nanoparticles uniformly loaded on the surface of the nanorod-shaped MnO2 carrier; the MnO2@LaO x The preparation method of the catalyst comprises the following steps: under stirring, oxalic acid solution is added into a nanorod-shaped MnO2 carrier dispersion liquid and stirring is kept for 10-60 min, then lanthanum nitrate solution is added and stirring is kept for a period of time, and then the solid is washed, dried and calcined at 300-500 DEG C to obtain the MnO2@LaO x The catalyst. The application exhibits significant advantages in improving catalytic efficiency, reducing energy consumption, reducing environmental pollution, enhancing stability and simplifying the preparation process.

Description

Technical Field

[0001] This invention relates to the field of gaseous pollutant treatment technology, and specifically to a method for plasma-catalytic degradation of trimethylamine. Background Technology

[0002] Trimethylamine is a colorless gas with a fishy, ​​foul odor. It has a low boiling point, is highly volatile, and is flammable and toxic. The main hazards of trimethylamine to humans include irritation to the eyes, nose, throat, and respiratory tract. Long-term exposure can lead to dryness and discomfort in the eyes, nose, and throat, and in severe cases, can cause intense burning and redness of the skin. Therefore, the emission of trimethylamine not only pollutes the environment but also poses a serious threat to human health and safety; its remediation is of significant environmental and safety importance.

[0003] Plasma technology, as an emerging environmental remediation technology, is widely used for the treatment of gaseous pollutants due to its ability to generate high-energy electrons and reactive particles at room temperature, effectively decomposing organic pollutants. High-energy electrons in the plasma system can directly break the chemical bonds in organic molecules, achieving deodorization. However, plasma technology alone has some limitations in treating organic waste gas, such as low utilization of high-energy electrons leading to low treatment efficiency, and significant ozone escape in the exhaust gas causing secondary pollution. To overcome these problems, combining plasma technology with a catalyst can effectively improve the utilization rate of high-energy electrons, reduce ozone generation, and decrease the formation of byproducts. The introduction of a catalyst not only promotes the reaction between reactive species generated by the plasma and pollutants but also effectively reduces ozone escape and the formation of secondary pollutants.

[0004] Based on the above analysis, the existing technology has the following main problems: (1) The catalyst has low utilization efficiency for high-energy electrons in the field; (2) Traditional loading methods for surface nanoparticles lead to nanoparticle aggregation and poor dispersibility; (3) There is limited research on existing catalysts for nitrogen-containing odorous pollutants.

[0005] Patent specification CN105772072A discloses a catalyst suitable for low-temperature plasma treatment of organic waste gas, its preparation, and its application. The catalyst mainly consists of a molecular sieve and transition metals and rare earth metals supported on the molecular sieve. The transition metal is manganese or titanium, and the molar ratio of rare earth metal to transition metal is 0.5~2:1. The catalyst preparation method involves co-impregnating the rare earth metal and transition metal onto the molecular sieve and calcining it at 500~800℃. This catalyst can be used for dielectric barrier discharge (DBD) treatment of trimethylamine organic waste gas. The beneficial effect of this patented technology is that by loading specific rare earth metal cerium and transition metals titanium or manganese under specific conditions, proportions, and optimized preparation processes, heterojunctions and spinel structures can be formed on the catalyst surface, enhancing the electrical performance of the DBD reaction. Simultaneously, the Ce element can improve the catalyst dispersion. Example 3 of the patent specification provides a case of obtaining a catalyst by co-impregnating lanthanum + manganese onto silica and calcining it at 600℃, and using it for DBD treatment of toluene, but the effect was not good, with a toluene conversion rate of only 40%. Summary of the Invention

[0006] In a first aspect, the present invention provides a method for plasma-catalyzed degradation of trimethylamine, using MnO2@LaO x The catalyst is a low-temperature plasma catalyst, which is used for plasma catalytic degradation of trimethylamine.

[0007] A method for plasma-catalyzed degradation of trimethylamine, comprising: applying MnO2@LaO x The catalyst is filled into the discharge bed region of the plasma reactor to carry out plasma catalytic degradation of trimethylamine; The MnO2@LaO x The catalyst comprises a nanorod-shaped MnO2 support and lanthanum oxide (LaO2) uniformly supported on the surface of the nanorod-shaped MnO2 support. x Nanoparticles; The MnO2@LaO x The catalyst preparation method includes: adding oxalic acid solution to a nanorod-shaped MnO2 support dispersion under stirring and maintaining stirring for 10-60 min (e.g., 30 min), then adding lanthanum nitrate solution and maintaining stirring for a period of time, then taking the solid, washing, drying, and calcining at 300-500℃ (e.g., 400℃) to obtain the MnO2@LaO2 catalyst. x catalyst.

[0008] In some preferred embodiments, the preparation method of the nanorod-shaped MnO2 support adopts a one-step hydrothermal method without calcination.

[0009] In some preferred embodiments, the method for preparing the nanorod-shaped MnO2 support includes: Manganese sulfate and potassium permanganate were dissolved in deionized water and stirred. The resulting mixture was placed in a sealed container and subjected to hydrothermal reaction at 100-160°C (e.g., 140°C) under autogenous pressure for 8-15 hours (e.g., 12 hours) to obtain the nanorod-shaped MnO2 support.

[0010] In some preferred embodiments, the molar ratio of manganese sulfate to potassium permanganate is 2:1 in the preparation method of the nanorod-shaped MnO2 support.

[0011] In some preferred embodiments, the stirring time in the preparation method of the nanorod-shaped MnO2 support is 60 minutes.

[0012] In some preferred embodiments, the mass ratio of lanthanum oxide (La2O3) to the nanorod-shaped MnO2 support is 1:10 to 50, for example, 1:20.

[0013] In some preferred embodiments, the MnO2@LaO x In the catalyst preparation method, the molar ratio of nanorod-shaped MnO2 support to oxalic acid is 2:1. At this molar ratio, MnO2@LaO2 is obtained. x The catalyst is most effective in plasma-catalyzing the degradation of trimethylamine.

[0014] In some preferred embodiments, the MnO2@LaO x In the catalyst preparation method, the oxalic acid solution has a mass concentration of 10%.

[0015] In some preferred embodiments, the MnO2@LaO x In the catalyst preparation method, lanthanum nitrate solution is added and stirred for 6 hours.

[0016] In some preferred embodiments, the MnO2@LaO x In the catalyst preparation method, the calcination atmosphere is air.

[0017] In some preferred embodiments, the MnO2@LaO x In the catalyst preparation method, the calcination time is 1 to 2 hours.

[0018] Secondly, this invention provides MnO2@LaO x Applications of catalysts in the plasma-catalyzed degradation of trimethylamine include: using MnO2@LaO x The catalyst is filled into the discharge bed region of the plasma reactor to carry out plasma catalytic degradation of trimethylamine; The MnO2@LaO x The catalyst comprises a nanorod-shaped MnO2 support and lanthanum oxide nanoparticles uniformly supported on the surface of the nanorod-shaped MnO2 support. The MnO2@LaO x The catalyst preparation method includes: adding oxalic acid solution to a nanorod-shaped MnO2 support dispersion under stirring and maintaining stirring for 10-60 min (e.g., 30 min), then adding lanthanum nitrate solution and maintaining stirring for a period of time, then taking the solid, washing, drying, and calcining at 300-500℃ (e.g., 400℃) to obtain the MnO2@LaO2 catalyst. x catalyst.

[0019] In some preferred embodiments, the preparation method of the nanorod-shaped MnO2 support adopts a one-step hydrothermal method without calcination.

[0020] In some preferred embodiments, the method for preparing the nanorod-shaped MnO2 support includes: Manganese sulfate and potassium permanganate were dissolved in deionized water and stirred. The resulting mixture was placed in a sealed container and subjected to hydrothermal reaction at 100-160°C (e.g., 140°C) under autogenous pressure for 8-15 hours (e.g., 12 hours) to obtain the nanorod-shaped MnO2 support.

[0021] In some preferred embodiments, the molar ratio of manganese sulfate to potassium permanganate is 2:1 in the preparation method of the nanorod-shaped MnO2 support.

[0022] In some preferred embodiments, the stirring time in the preparation method of the nanorod-shaped MnO2 support is 60 minutes.

[0023] In some preferred embodiments, the mass ratio of lanthanum oxide (La2O3) to the nanorod-shaped MnO2 support is 1:10 to 50, for example, 1:20.

[0024] In some preferred embodiments, the MnO2@LaO x In the catalyst preparation method, the molar ratio of nanorod-shaped MnO2 support to oxalic acid is 2:1. At this molar ratio, MnO2@LaO2 is obtained. x The catalyst is most effective in plasma-catalyzing the degradation of trimethylamine.

[0025] In some preferred embodiments, the MnO2@LaO x In the catalyst preparation method, the oxalic acid solution has a mass concentration of 10%.

[0026] In some preferred embodiments, the MnO2@LaO x In the catalyst preparation method, lanthanum nitrate solution is added and stirred for 6 hours.

[0027] In some preferred embodiments, the MnO2@LaO x In the catalyst preparation method, the calcination atmosphere is air.

[0028] In some preferred embodiments, the MnO2@LaO x In the catalyst preparation method, the calcination time is 1 to 2 hours.

[0029] This invention uses oxalic acid to etch nanorod-shaped MnO2 supports to create vacancies suitable for loading lanthanum oxide nanoparticles on the surface of the nanorod-shaped MnO2 supports.

[0030] This invention MnO2@LaO x The catalyst preparation method is simple, low-cost, and easy to scale up. Furthermore, it possesses multiple functions in the plasma-catalyzed degradation of trimethylamine: the oxalic acid-etched nanorod-shaped MnO2 support exhibits strong electric field response, and this unique structure allows it to effectively capture and utilize high-energy electrons within the field; the oxalic acid-etched nanorod-shaped MnO2 support surface is uniformly loaded with LaO2. x Nanoparticles enhance the adsorption capacity of trimethylamine, enabling effective adsorption of trimethylamine; the redox pair formed between La and Mn accelerates the oxidation process, achieving higher removal efficiency with low energy consumption.

[0031] This invention reduces ozone escape and byproduct generation during the plasma-catalyzed degradation of trimethylamine, thereby reducing environmental pollution. It demonstrates unique advantages and broad application prospects in the application of plasma-catalyzed degradation of trimethylamine.

[0032] Compared with the prior art, the beneficial effects of this invention are as follows: The nanorod-shaped MnO2@LaO of the present invention x Plasma catalysts are produced by uniformly loading LaO2 onto the surface of oxalic acid-etched nanorod-shaped MnO2. x Nanoparticles form effective redox pairs, significantly improving the degradation efficiency of trimethylamine while reducing energy consumption.

[0033] This invention employs oxalic acid etching to process LaO. x The loading of nanoparticles effectively improved the particle dispersion and enhanced the interaction between MnO2 nanorods and LaO2. x Interactions between nanoparticles.

[0034] This invention demonstrates significant advantages in improving catalytic efficiency, reducing energy consumption, minimizing environmental pollution, enhancing stability, and simplifying the preparation process. Attached Figure Description

[0035] Figure 1 MnO2@LaO2 is from Example 1 x Scanning electron microscope (SEM) image of the catalyst.

[0036] Figure 2MnO2@LaO2 is from Example 1 x Transmission electron microscopy (TEM) image of the catalyst. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0038] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0039] Example 1: MnO2 nanorods were prepared via a one-step hydrothermal method. Manganese sulfate and potassium permanganate were dissolved in deionized water at a molar ratio of 2:1. After stirring for 60 minutes, the mixture was placed in a polytetrafluoroethylene liner for hydrothermal reaction at 140°C for 12 hours to obtain the MnO2 sample. Subsequently, 0.5 g of the MnO2 sample was dissolved in water, and a 10 wt% oxalic acid solution (oxalic acid:MnO2 molar ratio of 1:2) was added while stirring for 30 minutes. Next, lanthanum nitrate solution was added to the mixture at a La2O3:MnO2 mass ratio of 1:20, and stirring continued for 6 hours. After filtration, washing, and drying, the mixture was calcined in air at 400°C for 1 hour to obtain nanorod-shaped MnO2@LaO2. x Plasma catalyst.

[0040] Catalyst performance testing: The nanorod-shaped MnO2@LaO2 prepared according to the above steps... x 0.2 g of plasma catalyst was added to the discharge bed region of the plasma reactor for performance testing of plasma-catalyzed degradation of trimethylamine. In this embodiment, a pulse-modulated power supply was used to simulate odorous waste gas composed of N2, O2, and trimethylamine, with a trimethylamine concentration of 30 ppmv, O2 concentration of 20 vol%, and a waste gas flow rate of 2 L / min. Gas chromatography was used to determine the trimethylamine concentration in the waste gas, and an ozone analyzer was used to determine the ozone concentration. At an energy density of 110 J / L, the trimethylamine removal rate reached 90%; at an energy density of 130 J / L, the trimethylamine removal rate reached 100%, and the ozone concentration in the waste gas was less than 10 ppmv.

[0041] MnO2@LaO synthesized in Example 1 of this invention x The SEM and TEM images of the catalyst are as follows: Figure 1 , Figure 2 As shown.

[0042] Comparative Example 1: The performance was tested using the nanorod-shaped MnO2 from Example 1 as a catalyst, and the test conditions were the same as those in Example 1.

[0043] At an energy density of 130 J / L, the trimethylamine removal rate reached 67%, while the ozone concentration in the exhaust gas was approximately 20.5 ppmv. At an energy density of 150 J / L, the trimethylamine removal rate reached 91%, and the ozone concentration in the exhaust gas was approximately 32 ppmv.

[0044] Example 2: The only difference from Example 1 is that the hydrothermal reaction temperature in the one-step hydrothermal method for preparing nanorod-like MnO2 is changed to 100°C, while the other preparation and testing conditions are the same.

[0045] At an energy density of 130 J / L, the removal rate of trimethylamine was 75%, while the ozone concentration in the exhaust gas was approximately 16.5 ppmv. At an energy density of 150 J / L, the removal rate of trimethylamine reached 94%, and the ozone concentration in the exhaust gas was approximately 23 ppmv.

[0046] Example 3: The only difference from Example 1 is that the hydrothermal reaction time in the MnO2 prepared by the one-step hydrothermal method for nanorod structures is changed to 8 hours, while the other preparation and testing conditions are the same.

[0047] At an energy density of 130 J / L, the removal rate of trimethylamine was 75%, while the ozone concentration in the exhaust gas was approximately 13.8 ppmv. At an energy density of 150 J / L, the removal rate of trimethylamine reached 88%, and the ozone concentration in the exhaust gas was approximately 19.4 ppmv.

[0048] Example 4: The only difference from Example 1 is that the calcination temperature is changed to 300°C, while the other preparation and testing conditions are the same.

[0049] At an energy density of 130 J / L, the removal rate of trimethylamine was 83%, while the ozone concentration in the exhaust gas was approximately 15.2 ppmv. At an energy density of 150 J / L, the removal rate of trimethylamine reached 92%, and the ozone concentration in the exhaust gas was approximately 21.8 ppmv.

[0050] Example 5: The only difference from Example 1 is that lanthanum nitrate solution was added to the mixed system at a mass ratio of La2O3:MnO2 of 1:50; all other preparation and testing conditions were the same.

[0051] At an energy density of 130 J / L, the removal rate of trimethylamine was 75%, while the ozone concentration in the exhaust gas was approximately 17.4 ppmv. At an energy density of 150 J / L, the removal rate of trimethylamine reached 89.5%, and the ozone concentration in the exhaust gas was approximately 24.9 ppmv.

[0052] Example 6: The only difference from Example 1 is that lanthanum nitrate solution was added to the mixed system at a mass ratio of La2O3:MnO2 of 1:10; all other preparation and testing conditions were the same.

[0053] At an energy density of 130 J / L, the removal rate of trimethylamine was 91%, while the ozone concentration in the exhaust gas was approximately 8.8 ppmv. At an energy density of 150 J / L, the removal rate of trimethylamine reached 96.2%, and the ozone concentration in the exhaust gas was approximately 13.5 ppmv.

[0054] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for plasma-catalyzed degradation of trimethylamine, characterized in that, include: MnO2@LaO x The catalyst is filled into the discharge bed region of the plasma reactor to carry out plasma catalytic degradation of trimethylamine; The MnO2@LaO x The catalyst comprises a nanorod-shaped MnO2 support and lanthanum oxide nanoparticles uniformly supported on the surface of the nanorod-shaped MnO2 support. The MnO2@LaO x The catalyst preparation method includes: adding oxalic acid solution to a nanorod-shaped MnO2 support dispersion under stirring and maintaining stirring for 10-60 min, then adding lanthanum nitrate solution and maintaining stirring for a period of time, then taking the solid, washing, drying, and calcining at 300-500℃ to obtain the MnO2@LaO2 catalyst. x catalyst.

2. The method for plasma-catalyzed degradation of trimethylamine according to claim 1, characterized in that, The MnO2@LaO x In the preparation method of the catalyst: the solid is washed, dried, and calcined at 400℃ to obtain the MnO2@LaO2 catalyst. x catalyst.

3. The method for plasma-catalyzed degradation of trimethylamine according to claim 1, characterized in that, The preparation method of the nanorod-shaped MnO2 support includes: Manganese sulfate and potassium permanganate were dissolved in deionized water and stirred. The resulting mixture was placed in a sealed container and subjected to hydrothermal reaction at 100-160°C for 8-15 hours under autogenous pressure to obtain the nanorod-shaped MnO2 support.

4. The method for plasma-catalyzed degradation of trimethylamine according to claim 3, characterized in that, In the preparation method of the nanorod-shaped MnO2 support: The resulting mixture was placed in a sealed container and subjected to hydrothermal reaction at 140°C for 12 hours under autogenous pressure to obtain the nanorod-shaped MnO2 support.

5. The method for plasma-catalyzed degradation of trimethylamine according to claim 3, characterized in that, In the preparation method of the nanorod-shaped MnO2 support: The molar ratio of manganese sulfate to potassium permanganate is 2:1; The stirring time is 60 minutes.

6. The method for plasma-catalyzed degradation of trimethylamine according to claim 1, characterized in that, The mass ratio of lanthanum oxide (La2O3) to the nanorod-shaped MnO2 support is 1:10~50.

7. The method for plasma-catalyzed degradation of trimethylamine according to claim 6, characterized in that, The mass ratio of lanthanum oxide (La2O3) to the nanorod-shaped MnO2 support is 1:

20.

8. The method for plasma-catalyzed degradation of trimethylamine according to claim 1, characterized in that, The MnO2@LaO x In the preparation method of catalyst: The molar ratio of nanorod-shaped MnO2 support to oxalic acid is 2:1; The oxalic acid solution has a mass concentration of 10%; Add lanthanum nitrate solution and keep stirring for 6 hours; The calcination atmosphere is air; The calcination time is 1 to 2 hours. 9.MnO2@LaO x The application of the catalyst in the plasma-catalyzed degradation of trimethylamine is characterized by, include: MnO2@LaO x The catalyst is filled into the discharge bed region of the plasma reactor to carry out plasma catalytic degradation of trimethylamine; The MnO2@LaO x The catalyst comprises a nanorod-shaped MnO2 support and lanthanum oxide nanoparticles uniformly supported on the surface of the nanorod-shaped MnO2 support. The MnO2@LaO x The catalyst preparation method includes: adding oxalic acid solution to a nanorod-shaped MnO2 support dispersion under stirring and maintaining stirring for 10-60 min, then adding lanthanum nitrate solution and maintaining stirring for a period of time, then taking the solid, washing, drying, and calcining at 300-500℃ to obtain the MnO2@LaO2 catalyst. x catalyst.

10. The application according to claim 9, characterized in that, The MnO2@LaO x In the preparation method of the catalyst: the solid is washed, dried, and calcined at 400℃ to obtain the MnO2@LaO2 catalyst. x catalyst.

11. The application according to claim 9, characterized in that, The preparation method of the nanorod-shaped MnO2 support includes: Manganese sulfate and potassium permanganate were dissolved in deionized water and stirred. The resulting mixture was placed in a sealed container and subjected to hydrothermal reaction at 100-160°C for 8-15 hours under autogenous pressure to obtain the nanorod-shaped MnO2 support.

12. The application according to claim 11, characterized in that, In the preparation method of the nanorod-shaped MnO2 support: The resulting mixture was placed in a sealed container and subjected to hydrothermal reaction at 140°C for 12 hours under autogenous pressure to obtain the nanorod-shaped MnO2 support.

13. The application according to claim 11, characterized in that, In the preparation method of the nanorod-shaped MnO2 support: The molar ratio of manganese sulfate to potassium permanganate is 2:1; The stirring time is 60 minutes.

14. The application according to claim 9, characterized in that, The mass ratio of lanthanum oxide (La2O3) to the nanorod-shaped MnO2 support is 1:10~50.

15. The application according to claim 14, characterized in that, The mass ratio of lanthanum oxide (La2O3) to the nanorod-shaped MnO2 support is 1:

20.

16. The application according to claim 9, characterized in that, The MnO2@LaO x In the preparation method of catalyst: The molar ratio of nanorod-shaped MnO2 support to oxalic acid is 2:1; The oxalic acid solution has a mass concentration of 10%; Add lanthanum nitrate solution and keep stirring for 6 hours; The calcination atmosphere is air; The calcination time is 1 to 2 hours.

Images