A ZSM-5 molecular sieve loaded CuO catalyst, a preparation method and application thereof

Abstract

The application relates to a ZSM-5 molecular sieve loaded CuO catalyst and a preparation method and application thereof. The specific preparation steps are as follows: (1) preparing a water solution from a silicon source and an aluminum source; (2) adding a template agent and a surfactant into the water solution prepared in step (1), and preparing ellipsoidal ZSM-5 molecular sieve through hydrothermal preparation; (3) preparing a transparent solution from a copper salt; (4) loading the copper salt solution to the ellipsoidal ZSM-5 molecular sieve, and obtaining the ellipsoidal ZSM-5 molecular sieve loaded CuO (111) crystal plane catalyst for preparing acetic acid from methane and carbon dioxide after calcination under a protective atmosphere. The ellipsoidal ZSM-5 molecular sieve loaded CuO (111) catalyst provided by the application can catalyze the direct preparation of acetic acid from the co-conversion of methane and carbon dioxide, and has good catalytic activity and selectivity.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, to a ZSM-5 molecular sieve supported CuO catalyst and its preparation method and application, and in particular to an ellipsoidal ZSM-5 molecular sieve supported CuO (111) catalyst and its preparation method and application. Background Technology

[0002] Excessive greenhouse gas emissions leading to global warming are drawing unprecedented global attention. The increase in atmospheric CH4 and CO2 concentrations has triggered a series of environmental problems, including global warming, glacial melting, and ocean acidification. Converting CH4 and CO2 into clean fuels and chemicals can not only eliminate the impact of greenhouse gases but also reduce dependence on fossil fuels. In 2021, carbon dioxide and methane emissions accounted for over 90% of global emissions, and are considered major anthropogenic greenhouse gases (OurWorldInData.org. https: / / ourworldindata.org / co2-and-greenhouse-gas-emissions). Furthermore, these two gases have high bond energies and are considered C1 feedstocks for bulk chemical and fuel production, aligning with the vision of achieving a "dual-carbon" target strategy. Carbon dioxide and methane have attracted significant attention not only from energy and environmental perspectives but also due to their potential as alternative economic feedstocks. For the catalytic conversion of CH4 and CO2, surface activation using heterogeneous catalysts is considered one of the feasible methods to overcome extremely high thermodynamic and kinetic stability (Phys Chem Chem Phys., 2012, 14, 16588-16594). However, this reaction is thermodynamically very unfavorable (ΔG). 0 =16.98 kcal·mol -1 According to assessments, even under specific experimental conditions (725 °C, 100 atm, CO2 (95 vol%) and CH4 (5 vol%)), the thermodynamic equilibrium conversion rate of methane is as low as 1.6 × 10⁻⁶. -6 Furthermore, the simultaneous activation of two molecules seems attractive, but is more difficult [Nature., 2002, 417, 507-514.].

[0003] For acetic acid, the most common acetic acid production process is the methanol carbonylation process, which involves three steps in the presence of rhodium and iridium complexes and the HI system [J Catal., 1977, 50, 494-507.]. Therefore, simultaneously activating CH4 and CO2 molecules in the same catalyst system to produce acetic acid via methane carboxylation in a one-step process has significant advantages compared to the current main acetic acid processes. However, due to the high thermodynamic barrier, simultaneously activating two reactant molecules is very challenging. The earliest report described the homogeneous production of acetic acid from CH4 and CO2 in CF3COOH solvent using a Pd / Cu complex and K2S2O8 (15 mol%) as an oxidant, with an acetic acid yield of 7% (Org Lett., 2003, 5, 3193-3196). Heterogeneous catalytic conversion methods mostly use Co-Cu, V2O5-PdCl2 / Al2O3, Pd & Rh / TiO2, Pd & Rh / SiO2, Pd / C, and Pt / alumina as catalysts, employing two-step, stepwise, periodic, or cyclic reaction modes, with yields below 45 μmol·g. cat -1 ·h -1 The selectivity is also poor [J Nat Gas Chem., 2004, 13, 113-115. Fuel Process Technol., 2007, 88, 319-324.].

[0004] ZSM-5 molecular sieves have been widely used in fine chemicals, petroleum refining, environmental protection, and adsorption separation due to their excellent pore selectivity, ion exchange capacity, tunable acidity, and good hydrothermal stability (JCatal., 2023, 417, 226-247.). However, conventional microporous ZSM-5 molecular sieves have very limited mass transfer and diffusion capabilities, especially in the catalytic conversion of C1 molecules, where they suffer from low accessibility to acidic sites and poor resistance to carbon deposition. Therefore, the synthesis and application of ZSM-5 molecular sieves with special morphologies possessing numerous advantages have gradually become a research hotspot (Chem EnginJour, 2024, 483, 149123-149133.). Regarding the selection of active components, copper oxide, a transition metal oxide, is widely used in the preparation of supported catalysts due to its wide availability, low cost, good environmental compatibility, and high redox activity. However, CuO / ZSM-5 catalysts prepared by conventional methods in the present technology still have significant performance bottlenecks. On the one hand, copper oxide nanoparticles supported by traditional impregnation or precipitation methods are often unevenly dispersed on the ZSM-5 surface, with a wide particle size distribution. Furthermore, they are prone to migration and aggregation during subsequent calcination or reaction, leading to a decrease in the number of surface active sites and making it difficult to meet the requirements for long-term catalytic stability. On the other hand, deeper research shows that the catalytic activity of copper oxide exhibits a significant crystal facet dependence. Controlling the surface atomic arrangement, electronic structure, and defect states through crystal facet engineering has become a key strategy for optimizing activity and selectivity. However, how to achieve directional control of the exposed crystal facets of copper oxide in supported catalysts remains a technical challenge in this field. Conventional supports such as amorphous silica or commercially available ZSM-5 molecular sieves lack effective guidance for CuO crystal growth, resulting in supported copper oxide particles often existing in a thermodynamically stable mixed crystal facet form, making it difficult to expose the highly active (111) crystal facet.

[0005] Therefore, developing a method for a CuO-supported ellipsoidal ZSM-5 catalyst with high activity and a single exposed crystal facet is of great significance in this field. Summary of the Invention

[0006] One object of the present invention is to provide a CuO catalyst supported on ZSM-5 molecular sieve. Another object of the present invention is to provide a method for preparing the above-mentioned catalyst. A further object of the present invention is to provide the application of the above-mentioned catalyst in the co-conversion of CH4 and CO2 to prepare acetic acid.

[0007] The technical solution of the present invention is as follows: a ZSM-5 molecular sieve supported CuO catalyst; characterized in that the support is a ZSM-5 molecular sieve with an ellipsoidal structure, the active component is CuO, wherein the loading mass of CuO is 0.01~5% of the mass of the ZSM-5 support, and the loaded CuO particles expose the (111) crystal plane.

[0008] This invention also provides a method for preparing the above-mentioned ZSM-5 molecular sieve-supported CuO catalyst, the specific steps of which are as follows:

[0009] (1) Add silicon source and aluminum source to water and stir to prepare an aqueous solution;

[0010] (2) Add the template agent and surfactant to the aqueous solution prepared in step (1), and after hydrothermal reaction, cool, filter and vacuum dry;

[0011] (3) Add copper salt to solvent to make a transparent solution; grind the solid obtained in step (2) and add it to the transparent solution of copper salt for water bath aging. After filtration, washing and vacuum drying, grind the obtained solid and calcine it under a protective atmosphere to obtain ZSM-5 molecular sieve supported CuO catalyst.

[0012] The preferred silicon source in step (1) is one of silica sol, tetraethyl silicate or diatomaceous earth; the aluminum source is one of boehmite, aluminum nitrate, aluminum isopropoxide or sodium aluminate; the molar ratio of silicon source to aluminum source is 1: (1~25).

[0013] The preferred template agent in step (2) is one of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrapropylammonium bromide, or pyrrolidine; the surfactant is one of sodium dodecyl sulfate, sodium dodecyl sulfonate, or sodium stearate; the molar ratio of silicon source to template agent is 1:(1~10), and the molar ratio of silicon source to surfactant is 1:(1~10); the hydrothermal reaction temperature is 150~210 ℃, and the hydrothermal reaction time is 8~72 h.

[0014] In preferred step (3), the solvent is one of water, methanol or ethanol; the copper salt is one of copper nitrate, copper sulfate or copper citrate; the molar ratio of silicon source to copper salt is 1: (1~5), and the molar ratio of copper salt to solvent is 1: (4~500).

[0015] In preferred step (3), the water bath aging temperature is 20~80 ℃ and the aging time is 8~30 h; the vacuum drying temperature is 60~80 ℃ and the vacuum drying time is 8~24 h; the calcination temperature is 350 ℃~800 ℃ and the calcination time is 4~12 h; the protective atmosphere is one of hydrogen, argon, nitrogen or helium.

[0016] This invention also provides the application of the ZSM-5 molecular sieve-supported CuO catalyst in the production of acetic acid from methane and carbon dioxide. The specific steps are as follows:

[0017] (1) The catalyst described in claim 1 is packed into a plasma reactor, wherein the ratio of the packing mass of the catalyst to the volume of the plasma discharge region is 0.5~3 g / cm³. 3 The discharge length of the plasma reactor is 30~80 mm and the discharge gap is 1~4 mm;

[0018] (2) Control the temperature of the reactor in step (1) to be 0~80 ℃, set the actual plasma power to be 5~30 W, and the discharge frequency to be 5~15 Hz;

[0019] (3) Methane and carbon dioxide are continuously introduced into the plasma reactor, and the molar ratio of methane to carbon dioxide is controlled at (0.2~3):1, to prepare acetic acid.

[0020] Beneficial effects

[0021] This invention prepares a stable heterogeneous catalyst with ellipsoidal ZSM-5 molecular sieve as support and copper oxide with exposed CuO(111) crystal faces as active component. The catalyst of this invention is mainly used for plasma catalysis of methane and carbon dioxide to produce acetic acid. The method of this invention realizes the conversion of CH4 and CO2 into high-value-added product acetic acid under normal temperature and pressure conditions, avoiding the harsh requirements of high temperature and high pressure required by traditional CH4 and CO2 reactions. Moreover, the catalyst of this invention with ellipsoidal ZSM-5 molecular sieve supported on transition metal copper oxide and exposed copper oxide (111) crystal faces can significantly improve the selectivity and yield of the target product acetic acid. Attached Figure Description

[0022] Figure 1 This is a scanning electron microscope image of the CuO(111) / ZSM-5(Q) catalyst prepared in Example 4;

[0023] Figure 2 This is a transmission electron microscope image of the CuO(111) / ZSM-5(Q) catalyst prepared in Example 4. Detailed Implementation

[0024] The present invention will be described in more detail below with reference to the embodiments. These embodiments are merely descriptions of the best mode of implementation of the present invention and do not limit the scope of protection of the present invention in any way.

[0025] Example 1

[0026] Step 1. Add 0.001 mol tetraethyl silicate and 0.025 mol aluminum nitrate to deionized water and stir;

[0027] Step 2. Add 0.001 mol pyrrolidine and 0.002 mol sodium stearate to the above solution, stir, hydrothermally heat at 150 °C for 72 h, centrifuge, wash, and dry;

[0028] Step 3. Add 0.002 mol of copper sulfate to 1 mol of water to make an aqueous solution. Add the substance obtained in step (2) above, bathe in a water bath at 20 ℃ for 30 h, centrifuge, wash, and vacuum dry at 60 ℃ for 24 h. Calcine the obtained solid at 800 ℃ for 12 h under a hydrogen protective atmosphere to obtain an ellipsoidal ZSM-5 molecular sieve-supported CuO(111) catalyst, wherein the loading mass of copper oxide is 0.01%. The prepared catalyst has an ellipsoidal structure, and the supported CuO particles expose the (111) crystal plane. This catalyst is labeled as CuO(111) / ZSM-5(Q)-1.

[0029] Step 4. 0.2 g of catalyst was placed in a plasma device with a discharge length of 30 mm and a discharge gap of 1 mm. The actual power was set to 30 W, the reaction temperature was adjusted to 10 °C, the discharge frequency was 5 Hz, and methane and carbon dioxide in a molar ratio of 3:1 were introduced. The gaseous products were analyzed by chromatography, and the selectivity for acetic acid was 95.12%, with a space-time yield of 405 μmol·g⁻¹. cat -1 ·h -1 .

[0030] Example 2

[0031] Step 1. Add 0.01 mol silica sol and 0.01 mol sodium aluminate to deionized water and stir;

[0032] Step 2. Add 0.1 mol tetraethylammonium hydroxide and 0.08 mol sodium dodecyl sulfonate to the above solution, stir, hydrothermally heat at 160 °C for 12 h, centrifuge, wash, and dry;

[0033] Step 3. Add 0.01 mol copper sulfate to 0.1 mol ethanol to prepare an ethanol solution, add the substance obtained in step (2) above, bathe in a water bath at 30 ℃ for 26 h, centrifuge, wash, and vacuum dry at 70 ℃ for 20 h. Calcine the obtained solid at 700 ℃ for 10 h under an argon protective atmosphere to obtain an ellipsoidal ZSM-5 molecular sieve-supported CuO(111) catalyst, wherein the loading mass of copper oxide is 5%. The prepared catalyst has an ellipsoidal structure, and the supported CuO particles expose the (111) crystal plane. This catalyst is labeled as CuO(111) / ZSM-5(Q)-2.

[0034] Step 4. 0.8 g of catalyst was placed in a plasma device with a discharge length of 45 mm and a discharge gap of 2 mm. The actual power was set to 30 W, the reaction temperature was adjusted to 80 °C, and the discharge frequency was 15 Hz. Methane and carbon dioxide with a molar ratio of 2:1 were introduced. The gaseous products were analyzed by chromatography. The selectivity for acetic acid was 94.18%, and the space-time yield of acetic acid was 411 μmol·g. cat -1 ·h -1 .

[0035] Example 3

[0036] Step 1. Add 0.05 mol of diatomaceous earth and 0.1 mol of aluminum isopropoxide to deionized water and stir;

[0037] Step 2. Add 0.25 mol tetrapropylammonium bromide and 0.35 mol sodium dodecyl sulfate to the above solution, stir, hydrothermally heat at 180 °C for 10 h, centrifuge, wash, and dry;

[0038] Step 3. Add 0.25 mol copper citrate to 1 mol methanol to prepare a methanol solution, add the substance obtained in step (2) above, bathe in a water bath at 40 ℃ for 20 h, centrifuge, wash, and vacuum dry at 80 ℃ for 12 h. Calcine the obtained solid at 600 ℃ for 8 h under a nitrogen protective atmosphere to obtain an ellipsoidal ZSM-5 molecular sieve-supported CuO(111) catalyst, wherein the loading mass of copper oxide is 3%. The prepared catalyst has an ellipsoidal structure, and the supported CuO particles expose the (111) crystal plane. This catalyst is labeled as CuO(111) / ZSM-5(Q)-3.

[0039] Step 4. 1.3 g of catalyst was placed in a plasma apparatus with a discharge length of 58 mm and a discharge gap of 2 mm. The actual power was set to 10 W, the reaction temperature was adjusted to 60 °C, the discharge frequency was 10 Hz, and methane and carbon dioxide with a molar ratio of 0.2:1 were introduced. The gas phase products were analyzed by chromatography, and the selectivity for acetic acid was 92.32%, and the space-time yield of acetic acid was 441 μmol·g. cat -1 ·h -1 .

[0040] Example 4

[0041] Step 1. Add 0.04 mol of diatomaceous earth and 0.16 mol of aluminum isopropoxide to deionized water and stir;

[0042] Step 2. Add 0.25 mol tetrapropylammonium bromide and 0.24 mol sodium dodecyl sulfate to the above solution, stir, hydrothermally heat at 210 °C for 10 h, centrifuge, wash, and dry;

[0043] Step 3. Add 0.1 mol of copper nitrate to 20 mol of water to make an aqueous solution, add the substance obtained in step (2) above, bathe in a water bath at 60 ℃ for 16 h, centrifuge, wash, and vacuum dry at 80 ℃ for 8 h. Calcine the obtained solid at 500 ℃ for 6 h in a helium atmosphere to obtain an ellipsoidal ZSM-5 molecular sieve-supported CuO(111) catalyst, in which the loading mass of copper oxide is 2%; the prepared catalyst has an ellipsoidal structure (its SEM image is shown in Figure 1). Figure 1 As shown), and the supported CuO particles expose the (111) crystal plane (its TEM image is shown). Figure 2 As shown in the figure, the catalyst is labeled CuO(111) / ZSM-5(Q)-4.

[0044] Step 4. 2.2 g of catalyst was placed in a plasma apparatus with a discharge length of 62 mm and a discharge gap of 3 mm. The actual power was set to 10 W, the reaction temperature was adjusted to 20 °C, and the discharge frequency was 10 Hz. Methane and carbon dioxide with a molar ratio of 1:1 were introduced. The gaseous products were analyzed by chromatography. The selectivity for acetic acid was 96.61%, and the space-time yield of acetic acid was 470 μmol·g. cat -1 ·h -1 .

[0045] Example 5

[0046] Step 1. Add 0.03 mol tetraethyl silicate and 0.09 mol aluminum nitrate to deionized water and stir;

[0047] Step 2. Add 0.25 mol tetrapropylammonium bromide and 0.30 mol sodium dodecyl sulfate to the above solution, stir, hydrothermally heat at 210 °C for 8 h, centrifuge, wash, and dry;

[0048] Step 3. Add 0.1 mol of copper nitrate to 5 mol of water to make an aqueous solution, add the substance obtained in step (2) above, bathe in a water bath at 80 ℃ for 12 h, centrifuge, wash, and vacuum dry at 80 ℃ for 8 h. Calcine the obtained solid at 350 ℃ for 6 h in a helium protective atmosphere to obtain an ellipsoidal ZSM-5 molecular sieve-supported CuO(111) catalyst, wherein the loading mass of copper oxide is 0.4%. The prepared catalyst has an ellipsoidal structure, and the supported CuO particles expose the (111) crystal plane. This catalyst is labeled as CuO(111) / ZSM-5(Q)-5.

[0049] Step 4. 4.1 g of catalyst was placed in a plasma apparatus with a discharge length of 70 mm and a discharge gap of 4 mm. The actual power was set to 10 W, and the reaction temperature was adjusted to 50 °C. The discharge frequency was 10 Hz, and methane and carbon dioxide in a molar ratio of 1:1 were introduced. The gaseous products were analyzed by chromatography, and the selectivity for acetic acid was 93.54%, with a space-time yield of 460 μmol·g⁻¹. cat -1 ·h -1 .

[0050] Example 6

[0051] Step 1. Add 0.05 mol of diatomaceous earth and 1.25 mol of pseudoboehmite to deionized water and stir;

[0052] Step 2. Add 0.1 mol tetrapropylammonium hydroxide and 0.1 mol sodium dodecyl sulfate to the above solution, stir, hydrothermally heat at 210 °C for 8 h, centrifuge, wash, and dry;

[0053] Step 3. Add 0.1 mol of copper nitrate to 12 mol of water to make an aqueous solution, add the substance obtained in step (2) above, bathe in water at 80 ℃ for 8 h, centrifuge, wash, vacuum dry at 80 ℃ for 8 h, and calcine the obtained solid at 350 ℃ for 4 h in an argon protective atmosphere to obtain an ellipsoidal ZSM-5 molecular sieve supported CuO(111) catalyst, wherein the loading mass of copper oxide is 1%. The prepared catalyst has an ellipsoidal structure and the supported CuO particles expose the (111) crystal plane. The catalyst is labeled as CuO(111) / ZSM-5(Q)-6.

[0054] Step 4. 6.2 g of catalyst was placed in a plasma apparatus with a discharge length of 80 mm and a discharge gap of 4 mm. The actual power was set to 10 W, and the reaction temperature was adjusted to 40 °C. The discharge frequency was 10 Hz, and methane and carbon dioxide were introduced in a molar ratio of 1:1. The gaseous products were analyzed by chromatography, and the selectivity for acetic acid was 94.42%, with a space-time yield of 452 μmol·g⁻¹. cat -1 ·h -1 .

[0055] Comparative Example 1

[0056] 6.2 g of commercial CuO / ZSM-5 catalyst was placed in a plasma apparatus with a discharge length of 80 mm and a discharge gap of 4 mm. The actual power was set to 10 W, and the reaction temperature was adjusted to 40 °C. The discharge frequency was 10 Hz, and methane and carbon dioxide were introduced in a molar ratio of 1:1. The gaseous products were analyzed by chromatography, and the selectivity for acetic acid was 17.56%, with a space-time yield of acetic acid of 13 μmol·g⁻¹. cat -1 ·h -1 .

[0057] Comparative Example 2

[0058] 0.2 g of commercial CuO / ZSM-5 catalyst was placed in a plasma device with a discharge length of 30 mm and a discharge gap of 1 mm. The actual power was set to 30 W, the reaction temperature was adjusted to 10 °C, and the discharge frequency was 5 Hz. Methane and carbon dioxide in a molar ratio of 3:1 were introduced. The gas phase products were analyzed by chromatography, and the selectivity for acetic acid was 14.89%, with a space-time yield of acetic acid of 28 μmol·g⁻¹. cat -1 ·h -1 .

[0059] The performance test results of the CuO(111) / ZSM-5(Q) catalyst are shown in Table 1. The comparative examples show that, under the same conditions of using plasma technology to catalyze the conversion of methane and carbon dioxide to acetic acid, the ellipsoidal ZSM-5 molecular sieve-supported CuO(111) catalyst prepared in this invention exhibits higher selectivity for acetic acid. This indicates that the ellipsoidal ZSM-5 molecular sieve-supported CuO(111) catalyst prepared in this patent has good catalytic effect and product selectivity for this reaction.

[0060] Table 1. Performance test results of catalyst CuO(111) / ZSM-5(Q)

[0061] serial number Selectivity (%) <![CDATA[Maximum acetic acid production rate (μmol·g cat -1 ·h -1 ) <!-- 5 -->]]> Example 1 95.12 405 Example 2 94.18 411 Example 3 92.32 441 Example 4 96.61 470 Example 5 93.54 460 Example 6 94.42 452 Comparative Example 1 17.56 13 Comparative Example 2 14.89 28

Claims

1. A CuO catalyst supported on ZSM-5 molecular sieve; characterized in that, The support is ZSM-5 molecular sieve with an ellipsoidal structure, and the active component is CuO. The loading mass of CuO is 0.01~5% of the mass of ZSM-5 support, and the loaded CuO particles expose the (111) crystal plane.

2. A method for preparing the ZSM-5 molecular sieve-supported CuO catalyst as described in claim 1, comprising the following specific steps: (1) Add silicon source and aluminum source to water and stir to prepare an aqueous solution; (2) Add the template agent and surfactant to the aqueous solution prepared in step (1), and after hydrothermal reaction, cool, filter and vacuum dry; (3) Add copper salt to solvent to make a transparent solution; grind the solid obtained in step (2) and add it to the transparent solution of copper salt for water bath aging. After filtration, washing and vacuum drying, grind the obtained solid and calcine it under a protective atmosphere to obtain ZSM-5 molecular sieve supported CuO catalyst.

3. The method as described in claim 2, characterized in that: The silicon source mentioned in step (1) is one of silica sol, tetraethyl silicate or diatomaceous earth; the aluminum source is one of boehmite, aluminum nitrate, aluminum isopropoxide or sodium aluminate; the molar ratio of silicon source to aluminum source is 1: (1~25).

4. The method as described in claim 2, characterized in that: The template agent mentioned in step (2) is one of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrapropylammonium bromide or pyrrolidine; the surfactant is one of sodium dodecyl sulfate, sodium dodecyl sulfonate or sodium stearate; the molar ratio of silicon source to template agent is 1: (1~10), the molar ratio of silicon source to surfactant is 1: (1~10); the hydrothermal reaction temperature is 150~210 ℃, and the hydrothermal reaction time is 8~72 h.

5. The method as described in claim 2, characterized in that: In step (3), the solvent is one of water, methanol or ethanol; the copper salt is one of copper nitrate, copper sulfate or copper citrate; the molar ratio of silicon source to copper salt is 1: (1~5), and the molar ratio of copper salt to solvent is 1: (4~500).

6. The method as described in claim 2, characterized in that: In step (3), the water bath aging temperature is 20~80 ℃ and the aging time is 8~30 h; the vacuum drying temperature is 60~80 ℃ and the vacuum drying time is 8~24 h; the calcination temperature is 350 ℃~800 ℃ and the calcination time is 4~12 h; the protective atmosphere is one of hydrogen, argon, nitrogen or helium.

7. The application of the ZSM-5 molecular sieve-supported CuO catalyst as described in claim 1 in the production of acetic acid from methane and carbon dioxide.

8. The application as described in claim 7, wherein the specific steps are as follows: (1) The catalyst described in claim 1 is packed into a plasma reactor, wherein the ratio of the packing mass of the catalyst to the volume of the plasma discharge region is 0.5~3 g / cm³. 3 The discharge length of the plasma reactor is 30~80 mm and the discharge gap is 1~4 mm; (2) Control the temperature of the reactor in step (1) to be 0~80 ℃, set the actual plasma power to be 5~30 W, and the discharge frequency to be 5~15 Hz; (3) Methane and carbon dioxide are continuously introduced into the plasma reactor, and the molar ratio of methane to carbon dioxide is controlled at (0.2~3):1, to prepare acetic acid.

Images