Low-concentration methane oxidation method based on molecular sieve catalysts and ozone

Abstract

A method for the oxidation of low-concentration methane based on molecular sieve catalysts and ozone is disclosed. This method employs a molecular sieve catalyst that has undergone at least one ion exchange process, and additional ozone is introduced during the catalytic oxidation process to generate a synergistic effect, significantly reducing the ignition temperature of low-concentration CH4. This invention utilizes iron or cobalt ion-exchanged molecular sieves (Fe-SSZ-13, Co-SSZ-13, or Fe / Co-SSZ-13) to synergistically enhance the conversion rate of CH4 at low temperatures with ozone. This effectively reduces the ignition temperature of low-concentration CH4, eliminating the need for expensive precious metal materials and achieving low-temperature (<200℃) efficient oxidation of low-concentration (0.10%) CH4 at low cost. This provides a new technical approach to solving the problem of CH4 leakage in the exhaust gas of low-speed engines in natural gas ships.

Description

Technical Field

[0001] This invention relates to a technology in the field of environmental protection, specifically a technology at 80,000 mL·g -1 ·h -1 A low-concentration methane oxidation method based on molecular sieve catalyst and ozone at space velocity and 200℃. Background Technology

[0002] The concentration of unburned methane (CH4) in marine natural gas engines is approximately 0.05%-0.50%. Due to its difficulty in capture and utilization, it is usually directly emitted into the atmosphere. Catalytic oxidation is the main method for removing low-concentration CH4 from engine exhaust. However, CH4 has a stable tetrahedral structure and high chemical stability. To achieve a direct combustion temperature of 700℃ when the concentration reaches the combustible range (5%-15%) and oxygen is sufficient, it must be present. In contrast, the CH4 concentration in marine natural gas engine exhaust is below 0.50%, with low-speed and medium-speed engine exhaust temperatures of only 200-300℃ and 300-400℃ respectively, and containing a large amount of water vapor (approximately 10%-20%). This makes it difficult for CH4 to ignite properly, leading to leakage. Furthermore, the large amount of precious metals, primarily palladium (Pd), used in catalysts results in high catalyst development costs. Therefore, achieving low-temperature, high-efficiency oxidation of low-concentration CH4 at low cost has become a bottleneck scientific and technological challenge restricting the development of environmental protection equipment for natural gas-fired ships. Summary of the Invention

[0003] This invention addresses the problem that low-concentration CH4 in marine natural gas engine exhaust cannot be directly oxidized and removed, and the limitations of existing technologies in removing CH4 at concentrations between 80,000 and 240,000 mL·g. -1 ·h -1 To address the shortcomings in achieving low-temperature ignition and efficient oxidation of low-concentration methane under space velocity conditions, a low-concentration methane oxidation method based on molecular sieve catalysts and ozone is proposed. This method utilizes iron or cobalt ion-exchanged molecular sieves (Fe-SSZ-13, Co-SSZ-13, or Fe / Co-SSZ-13) to synergistically enhance CH4 conversion at low temperatures with ozone. This effectively reduces the ignition temperature of low-concentration CH4, eliminates the need for expensive precious metal materials, and achieves low-temperature (<200℃) efficient oxidation of low-concentration (0.10%) CH4 at low cost. This provides a new technical approach to solving the CH4 leakage problem in low-speed engine exhaust of natural gas ships.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a low-concentration methane oxidation method based on molecular sieve catalysts and ozone. It employs a molecular sieve catalyst that has undergone at least one ion exchange and introduces additional ozone during the catalytic oxidation process to generate a synergistic effect, thereby significantly reducing the ignition temperature of low-concentration CH4.

[0006] The at least one ion-exchange molecular sieve catalyst mentioned refers to Fe-SSZ-13, Co-SSZ-13 or Fe / Co-SSZ-13, wherein the ion exchange refers to: dissolving ferric nitrate nonahydrate Fe(NO3)3·9H2O or cobalt nitrate hexahydrate Co(NO3)2·6H2O in deionized water, adding H-SSZ-13 molecular sieve, mixing and then treating with water bath, and finally drying and calcining to obtain the catalyst.

[0007] The water bath treatment is preferably carried out by stirring at a constant temperature of 30°C for 1 hour until the mixture is fully dispersed and uniform, then adjusting the temperature of the water bath to 80°C and stirring at a constant temperature for 24 hours to ensure that the metal ions are fully exchanged onto the molecular sieve.

[0008] The drying process is preferably carried out in an oven at 110°C for 12 hours.

[0009] The calcination is preferably carried out in a muffle furnace at 550°C for 4 hours to obtain a powdered molecular sieve catalyst.

[0010] The H-SSZ-13 molecular sieve catalyst is preferably in the particle size range of 40 to 60 mesh, and the finished product has a specific surface area of ​​400-480 m². 2 / g, with a silicon-to-aluminum ratio of 10.

[0011] The low concentration of CH4 mentioned above has a volume ratio concentration of 0.10%.

[0012] In the catalytic oxidation process described above: the volume ratio concentration of methane (CH4) is 0.10%, the volume ratio concentration of oxygen (O2) is 10%, and the volume ratio concentration of ozone (O3) is 0.20%-0.80%.

[0013] The synergistic effect refers to the fact that the combined catalytic effect of molecular sieves and ozone in the catalytic oxidation system of low-concentration methane is greater than the sum of the catalytic effects of either molecular sieve or ozone alone. Furthermore, the synergistic effect of ozone with other oxide catalysts is far less pronounced than that of molecular sieves alone.

[0014] Technical effect

[0015] This invention utilizes ozone and iron-based or cobalt-based molecular sieve catalysts to synergistically remove low-concentration (0.10%) methane from marine engine exhaust. Under conditions where the exhaust temperature of marine low-speed and medium-speed natural gas engines is low (200-400℃) and contains a large amount of water vapor (concentration of about 10%-20%), the invention achieves, for the first time, ignition (conversion rate > 50%) and high-efficiency conversion (conversion rate > 90%) of low-concentration methane (0.10%) at 200℃ without the need for precious metal catalysts, by leveraging the synergistic effect of ozone and iron-based or cobalt-based molecular sieve catalysts. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the implementation environment for an example;

[0017] In the diagram: 1. High-purity oxygen cylinder; 2. CH4 / N2 dilution gas cylinder; 3. High-purity oxygen cylinder; 4. High-purity nitrogen cylinder; 5. Ozone generator; 6. Manual ball valve; 7. Mass flow controller; 8. Rotary tubular resistance furnace; 9. Quartz tube reactor loaded with molecular sieve catalyst; 10. Ozone concentration analyzer; 11. Fourier transform infrared spectrometer; 12. Ozone decomposition device. Detailed Implementation

[0018] In the following embodiments, the specific experimental procedures were as follows: H-SSZ-13 molecular sieves underwent metal ion exchange; the ion-exchange treated M-SSZ-13 (M = Fe, Ni, Co, Mn, Cu, Pd) molecular sieve catalyst was placed in a fixed-bed reactor, and natural gas engine exhaust gas was introduced; ozone was generated using an ozone generator and a certain volume fraction of ozone was introduced. Under normal pressure, the reaction temperature was 100 to 500°C; low concentrations of CH4 could be removed 90% to 100% within the 100-300°C range; and the simulated exhaust gas space velocity range of the natural gas engine was 80,000 to 240,000 mL·g. -1 ·h -1 The volume concentrations of O2, CH4, and ozone were 10%, 0.10%, 0.20%, 0.40%, 0.60%, and 0.80%, respectively. Example 1

[0019] Step 1) Synthesize Fe, Ni, Co, Mn, Cu, or Pd ion-exchange M-SSZ-13 molecular sieves using an ion exchange method. Specifically, this includes: weighing a certain mass of different metal nitrates, dissolving them in deionized water, and stirring thoroughly until the solution is homogeneous; then adding H-SSZ-13 molecular sieves to form mixtures A1, A2, A3, A4, A5, and A6; placing mixtures A1, A2, A3, A4, A5, and A6 in a water bath and stirring at 30°C for 1 hour until fully dispersed and homogeneous; then adjusting the water bath temperature to 80°C and stirring at this temperature for 24 hours to ensure complete exchange of the metal ions. After washing and filtering three times on a molecular sieve, the product was dried in an oven at 110℃ for 12 hours, and then calcined in a muffle furnace at 550℃ for 4 hours to obtain powdered M-SSZ-13 (M=Fe, Ni, Co, Mn, Cu, Pd) catalyst, namely products B1, B2, B3, B4, B5, and B6. After pressing, grinding, and sieving, molecular sieve catalyst particles of different metal ion exchange types (40-60 mesh) such as Fe-SSZ-13, Ni-SSZ-13, Co-SSZ-13, Mn-SSZ-13, Cu-SSZ-13, and Pd-SSZ-13 were finally obtained.

[0020] The different metal nitrates mentioned include ferric nitrate nonahydrate (Fe(NO3)3·9H2O), nickel nitrate hexahydrate (Ni(NO3)2·6H2O), cobalt nitrate hexahydrate (Co(NO3)2·6H2O), manganese nitrate dihydrate (Mn(NO3)2·2H2O), copper nitrate trihydrate (Cu(NO3)2·3H2O), and palladium nitrate dihydrate (Pd(NO3)2·2H2O), etc.

[0021] The mass of the different metal nitrates and H-SSZ-13 molecular sieves shall satisfy the following: 2.5 wt% of the mass fraction of H-SSZ-13 molecular sieve per 1 g.

[0022] The mixtures A1, A2, A3, A4, A5, and A6 are respectively: 1 g of H-SSZ-13 molecular sieve mixed with 0.181 g of Fe(NO3)3·9H2O, 0.124 g of Ni(NO3)2·6H2O, 0.123 g of Co(NO3)2·6H2O, 0.090 g of Mn(NO3)2·2H2O, 0.095 g of Cu(NO3)2·3H2O, and 0.299 g of Pd(NO3)2·2H2O.

[0023] The products B1, B2, B3, B4, B5, and B6 are molecular sieves of 2.5wt% Fe-SSZ-13, 2.5wt% Ni-SSZ-13, 2.5wt% Co-SSZ-13, 2.5wt% Mn-SSZ-13, 2.5wt% Cu-SSZ-13, and 2.5wt% Pd-SSZ-13, respectively.

[0024] Step 2) The M-SSZ-13 molecular sieve catalysts with different metal ion exchanges prepared in Step 1 are used in synergistic catalytic oxidation of low-concentration methane with ozone. Specifically, this includes: using... Figure 1 The reaction apparatus shown was used to evaluate the ability of molecular sieve catalysts such as 2.5wt%Fe-SSZ-13, 2.5wt%Co-SSZ-13, 2.5wt%Mn-SSZ-13, 2.5wt%Cu-SSZ-13, and 2.5wt%Pd-SSZ-13 to synergistically remove low concentrations of methane with ozone in a simulated exhaust atmosphere from a natural gas engine.

[0025] The simulated exhaust gas atmosphere of the natural gas engine is specifically defined as follows: under normal pressure, the reaction temperature range is 100 to 500°C, and the exhaust gas space velocity is 80,000 mL·g. -1 ·h -1 The volume concentration of O2 is 10%, and the volume concentration of CH4 is 0.10%. The volume concentration of O3 generated by the ozone generator is 0.60%.

[0026] Through specific experiments, the CH4 conversion rate and CO2 selectivity at 200℃ under normal pressure (expressed as X1% and S1%, respectively) and the temperature corresponding to 50% CH4 conversion rate (ignition temperature, T) were determined. 50 The evaluation standard for the methane oxidation performance of molecular sieve catalysts in the absence of ozone is based on the CH4 conversion and CO2 selectivity at 200℃ when O3 is introduced (expressed as X2% and S2%, respectively), and the temperature corresponding to 50% CH4 conversion (ignition temperature, T). 50 As an evaluation standard for the methane oxidation performance of molecular sieve catalysts under ozone conditions, the specific experimental data are as follows: Example 2

[0027] Step 1) Synthesis of Fe-SSZ-13 molecular sieve catalysts with different Fe addition amounts: Fe-SSZ-13 molecular sieve catalysts with different Fe addition amounts (Xwt%) were prepared using the ion exchange method. Specifically, different masses of ferric nitrate nonahydrate were weighed, dissolved in deionized water, and stirred thoroughly until the solution was homogeneous. Then, a certain mass of H-SSZ-13 molecular sieve was added to form mixtures A1, A2, A3, A4, and A5. Mixtures A1, A2, A3, A4, and A5 were placed in a water bath and stirred at 30°C for 2 hours until fully dispersed and homogeneous. The water bath temperature was then adjusted to 80°C and stirred at a constant temperature for 24 hours to ensure sufficient exchange of iron ions onto the molecular sieve. After washing and filtration three times, the mixture was dried in an oven at 110°C for 12 hours, and then calcined in a muffle furnace at 550°C for 4 hours to obtain powder (Xwt%). Fe-SSZ-13 (X=0.5, 1, 2.5, 5, 10) catalysts, namely products B1, B2, B3, B4, and B5, were obtained through steps such as tableting, grinding, and sieving. Finally, molecular sieve catalyst particle samples of different metal ion exchange 40-60 mesh were obtained, including 0.5wt%Fe-SSZ-13, 1wt%Fe-SSZ-13, 2.5wt%Fe-SSZ-13, 5wt%Fe-SSZ-13, and 10wt%Fe-SSZ-13.

[0028] The mixtures A1, A2, A3, A4, and A5 are respectively: 1 g of H-SSZ-13 molecular sieve mixed with 0.036 g of Fe(NO3)3·9H2O, 0.072 g of Fe(NO3)3·9H2O, 0.181 g of Fe(NO3)3·9H2O, 0.362 g of Fe(NO3)3·9H2O, and 0.723 g of Fe(NO3)3·9H2O.

[0029] The products B1, B2, B3, B4, and B5 are molecular sieves of 0.5wt%Fe-SSZ-13, 1wt%Fe-SSZ-13, 2.5wt%Fe-SSZ-13, 5wt%Fe-SSZ-13, and 10wt%Fe-SSZ-13, respectively.

[0030] Step 2) The Fe-SSZ-13 molecular sieve catalysts with different Fe addition amounts are synergistically catalyzed with ozone to oxidize low-concentration methane. Specifically, the following steps are taken: Figure 1 The reaction apparatus shown was used to evaluate the ability of molecular sieve catalysts of 0.5wt%Fe-SSZ-13, 1wt%Fe-SSZ-13, 2.5wt%Fe-SSZ-13, 5wt%Fe-SSZ-13, and 10wt%Fe-SSZ-13 to synergistically remove low concentrations of methane with ozone under different space velocity conditions in a simulated exhaust atmosphere of a natural gas engine.

[0031] The simulated exhaust atmosphere of the natural gas engine is as follows: under normal pressure, the reaction temperature range is 100 to 500°C, the O2 volume concentration is 10%, and the CH4 volume concentration is 0.10%. The O3 concentration generated by the ozone generator is 0.60%.

[0032] The different space velocity conditions mentioned are: 80,000 mL·g -1 ·h -1 160,000 mL·g -1 ·h -1 240,000 mL·g -1 ·h -1 .

[0033] The specific concentrations of ozone mentioned are: 80,000 mL·g -1 ·h -1 Under air velocity conditions, the volume concentration of ozone generated by the ozone generator in the total gas flow rate is 0.20%, 0.40%, 0.40%, and 0.80%.

[0034] Based on specific practical experiments, the CH4 conversion rate and CO2 selectivity at 200℃ under normal pressure (expressed as X1% and S1%, respectively) and the temperature corresponding to 50% CH4 conversion rate (ignition temperature, T) were determined. 50 The evaluation standard for the methane oxidation performance of molecular sieve catalysts in the absence of ozone is based on the CH4 conversion and CO2 selectivity at 200℃ when O3 is introduced (expressed as X2% and S2%, respectively), and the temperature corresponding to 50% CH4 conversion (ignition temperature, T). 50 This serves as an evaluation standard for the methane oxidation performance of molecular sieve catalysts under ozone conditions. Specific experimental data for Fe-SSZ-13 molecular sieve catalysts with different Fe addition amounts are as follows:

[0035] For the best-performing 1wt% Fe-SSZ-13 molecular sieve catalyst, the effects of reaction space velocity and ozone concentration on the synergistic methane oxidation ability were investigated. Specific experimental data are as follows: Example 3

[0036] Step 1) Synthesis of 1wt%Fe / Awt%Co-SSZ-13 molecular sieve catalysts with different Fe / Co ratios: Specifically, 1wt%Fe / Awt%Co-SSZ-13 molecular sieve catalysts (A=0.2, 0.4, 0.6, 0.8) with different Fe / Co addition amounts were prepared using the ion exchange method. The steps were as follows: Different masses of ferric nitrate nonahydrate and cobalt nitrate hexahydrate were weighed, dissolved in deionized water, and stirred thoroughly until the solution was homogeneous. Then, a certain mass of H-SSZ-13 molecular sieve was added to form mixtures A1, A2, A3, and A4. Mixtures A1, A2, A3, and A4 were placed in a water bath and stirred at 30℃ for 2 hours until fully homogeneous. The mixture was then evenly dispersed; the water bath temperature was adjusted to 80℃, and the mixture was stirred at a constant temperature for 24 hours to ensure that Fe ions were fully exchanged onto the molecular sieve. After washing and filtration three times, the mixture was dried in an oven at 110℃ for 12 hours, and then calcined in a muffle furnace at 550℃ for 4 hours to obtain powdered 1wt%Fe / Awt%Co-SSZ-13 (A=0.2, 0.4, 0.6, 0.8) catalysts, namely products B1, B2, B3, and B4. After pressing, grinding, and sieving, molecular sieve catalyst particle samples of 1wt%Fe / Awt%Co-SSZ-13 (A=0.2, 0.4, 0.6, 0.8) with different metal ion exchange meshes of 40-60 mesh were finally obtained.

[0037] The mixtures A1, A2, A3, and A4 are respectively: each 1 gh-SSZ-13 molecular sieve is a mixture of 0.072 g Fe(NO3)3·9H2O and 0.010 g Co(NO3)2·6H2O, 0.072 g Fe(NO3)3·9H2O and 0.020 g Co(NO3)2·6H2O, 0.072 g Fe(NO3)3·9H2O and 0.030 g Co(NO3)2·6H2O, and 0.072 g Fe(NO3)3·9H2O and 0.040 g Co(NO3)2·6H2O.

[0038] The products B1, B2, B3, and B4 are molecular sieve catalysts of 1wt%Fe / 0.2wt%Co-SSZ-13, 1wt%Fe / 0.4wt%Co-SSZ-13, 1wt%Fe / 0.6wt%Co-SSZ-13, and 1wt%Fe / 0.8wt%Co-SSZ-13, respectively.

[0039] Step 2) The synergistic removal of low-concentration methane using a 1wt%Fe / Awt%Co-SSZ-13 (A=0.2, 0.4, 0.6, 0.8) molecular sieve catalyst and ozone is employed. Specifically, the following steps are taken: Figure 1 The reaction apparatus shown was used to evaluate the ability of molecular sieve catalysts such as 1wt%Fe / 0.2wt%Co-SSZ-13, 1wt%Fe / 0.4wt%Co-SSZ-13, 1wt%Fe / 0.6wt%Co-SSZ-13, and 1wt%Fe / 0.8wt%Co-SSZ-13 to synergistically remove low concentrations of methane with ozone in a simulated exhaust atmosphere from a natural gas engine.

[0040] The simulated exhaust atmosphere of the natural gas engine is specifically defined as follows: under normal pressure conditions, the reaction temperature range is 100 to 500°C, the O2 volume concentration is 10%, the CH4 volume concentration is 0.10%, and the exhaust space velocity is 80,000 mL·g. -1 ·h -1 In addition, a 15% (v / v) water vapor (H2O) concentration is required for the water resistance test; a 0.005% (v / v) sulfur dioxide concentration is required for the sulfur resistance test. The ozone generator produces an O3 concentration of 0.60%.

[0041] Based on specific practical experiments, the CH4 conversion rate and CO2 selectivity at 200℃ under normal pressure (expressed as X1% and S1%, respectively) and the temperature corresponding to 50% CH4 conversion rate (ignition temperature, T) were determined. 50 The evaluation standard for the methane oxidation performance of molecular sieve catalysts in the absence of ozone is based on the CH4 conversion and CO2 selectivity at 200℃ when O3 is introduced (expressed as X2% and S2%, respectively), and the temperature corresponding to 50% CH4 conversion (ignition temperature, T). 50 As an evaluation standard for the methane oxidation performance of molecular sieve catalysts under ozone conditions, the specific experimental data are as follows:

[0042] For the best-performing 1wt%Fe / 0.2wt%Co-SSZ-13 molecular sieve catalyst, the CH4 conversion (X2%) and CO2 selectivity (S2%) of the catalyst synergistically with ozone in a 15% (v / v) water vapor atmosphere at 200℃ were investigated to characterize the catalyst's water resistance and sulfur resistance in a 0.005% SO2 atmosphere. Specific experimental data are as follows:

[0043] Compared with existing technologies, this method can significantly improve the conversion rate of low-concentration methane (CH4) at low temperatures. After...

[0044] The screening in Example 1, under the synergistic effect of 2.5 wt% Fe-SSZ-13 molecular sieve and ozone (O3) at a volume concentration of 0.60%, was able to achieve a concentration of 80,000 mL·g. -1 ·h -1 The ignition temperature of CH4 under space velocity conditions (the temperature corresponding to 50% conversion, T) 50 The temperature was reduced to 184℃; at 200℃, the CH4 conversion rate reached 58.6%, and the CO2 selectivity was 79.4%.

[0045] In Example 2, by further optimizing the amount of Fe added, under the synergistic effect of 1 wt% Fe-SSZ-13 molecular sieve and 0.60% O3 (volume concentration), it was possible to achieve a yield of 80,000 mL·g -1 ·h -1 Under airspeed conditions, the T of CH4 50 The temperature was lowered to 160℃; at 200℃, the CH4 conversion rate reached 80.8%, and the CO2 selectivity was 90.2%. Furthermore, with the synergistic effect of 1wt% Fe-SSZ-13 molecular sieve and 0.80% O3 (volume concentration), it was possible to achieve a conversion rate of 80,000 mL·g⁻¹. -1 ·h -1 Under airspeed conditions, the T of CH4 50 The temperature was lowered to 135℃; at 200℃, the CH4 conversion reached 98.2%, and the CO2 selectivity was 87.2%. Finally, at 240,000 mL·g -1 ·h -1 T of CH4 under high airspeed conditions 50 It can still be as low as 183℃; the CH4 conversion rate reaches 68.4% and the CO2 selectivity is 90.3% at 200℃.

[0046] In Example 3, further modification and optimization were achieved by adding Co. With the synergistic effect of 1wt% Fe / 0.2wt% Co-SSZ-13 molecular sieve and 0.60% O3 (volume concentration), it was possible to achieve a yield of 80,000 mL·g. -1 ·h-1 Under airspeed conditions, the T of CH4 50 The temperature was lowered to 160℃; at 200℃, the CH4 conversion rate reached 80.8%, and the CO2 selectivity was 90.2%. With the synergistic effect of 1wt% Fe / 0.2wt% Co-SSZ-13 molecular sieve and 0.60% O3 (volume concentration), after introducing 15% (volume fraction) water vapor at 200℃ for 4 hours, the CH4 conversion rate remained at 57.9%, and the CO2 selectivity remained at 95.9%; after shutting off the water vapor for 1 minute, the CH4 conversion rate increased to 93.2%, and the CO2 selectivity remained at 95.9%. After introducing 0.005% (volume fraction) sulfur dioxide at 200℃ for 4 hours, the CH4 conversion rate remained at 54.8%, and the CO2 selectivity remained at 95.7%; after desulfurization at 500℃ for 30 minutes, the CH4 conversion rate recovered to 87.5% and the CO2 selectivity remained at 95.4% within 6 hours of stabilization.

[0047] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A low-concentration methane oxidation method based on a molecular sieve catalyst and ozone, characterized by, By using a molecular sieve catalyst that has undergone at least one ion exchange and by introducing additional ozone during the catalytic oxidation process to generate a synergistic effect, the ignition temperature of low-concentration CH4 is significantly reduced. The at least one ion-exchange molecular sieve catalyst mentioned refers to Fe / Co-SSZ-13; the synergistic effect refers to the synergistic effect of 1wt% Fe / 0.2wt% Co-SSZ-13 molecular sieve and ozone with a volume concentration of 0.60%. The ion exchange refers to the process of dissolving ferric nitrate nonahydrate Fe(NO3)3·9H2O and cobalt nitrate hexahydrate Co(NO3)2·6H2O in deionized water, adding H-SSZ-13 molecular sieve, mixing, and then drying and calcining the mixture after water bath treatment.

2. The low-concentration methane oxidation method based on a molecular sieve catalyst and ozone according to claim 1, characterized by, The water bath treatment involves stirring at a constant temperature of 30°C for 1 hour until the ions are fully dispersed and homogeneous. Then, the temperature of the water bath is adjusted to 80°C and stirred at a constant temperature for 24 hours to ensure that the metal ions are fully exchanged onto the molecular sieve.

3. The method of claim 1, wherein the low-concentration methane oxidation method based on a molecular sieve catalyst and ozone is characterized by, The drying process involves drying in an oven at 110°C for 12 hours.

4. The method of claim 1, wherein the low-concentration methane oxidation method based on a molecular sieve catalyst and ozone is characterized by, The aforementioned calcination involves calcining the molecular sieve catalyst at 550°C for 4 hours in a muffle furnace to obtain powdered molecular sieve catalyst.

5. The low-concentration methane oxidation method based on molecular sieve catalyst and ozone according to claim 1, characterized in that, The H-SSZ-13 molecular sieve catalyst has a particle size range of 40 to 60 mesh, a specific surface area of 400-480 m 2 / g, and a silicon-aluminum ratio of 10.

6. The low-concentration methane oxidation method based on molecular sieve catalyst and ozone according to claim 1, characterized in that, In the catalytic oxidation process described above: the volume ratio concentration of methane (CH4) is 0.10%, the volume ratio concentration of oxygen (O2) is 10%, and the volume ratio concentration of ozone (O3) is 0.20%-0.80%.

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