A method of exhaust gas treatment

Abstract

The application discloses a waste gas treatment method. The application provides a waste gas treatment method which can efficiently treat waste gas containing nitrogen oxides and sulfur-containing gas. In order to treat the nitrogen oxides in the waste gas, the sulfur resistance of a FeMn / TiO2 catalyst can be significantly improved after the catalyst is doped with elemental ruthenium. When the molar ratio of Ru and Fe in the RuFeMn / TiO2 catalyst is 0.08-0.33:1, the initial conversion rate of NO in the waste gas and the conversion rate of NO after 5h are both higher than 80%, which indicates that the catalyst has good denitration performance and sulfur resistance and can meet the treatment requirements of nitrogen oxide waste gas.

Description

Technical Field

[0001] This invention relates to the field of waste gas separation, and more specifically to a waste gas treatment method. Background Technology

[0002] Nitrogen oxides (NOx) are a major class of gaseous pollutants that pose a series of hazards to human health and the ecological environment, such as affecting human health, causing photochemical smog and acid rain, damaging the ozone layer, and contributing to the greenhouse effect. In existing technologies, selective catalytic reduction (SCR) technology is applied to the removal of NOx. This involves using a catalyst to selectively react with NOx in the waste gas, reducing it to nitrogen gas. Among various catalysts, FeMn / TiO2 catalysts are widely used due to their good activity and environmental safety. However, when sulfur-containing substances are present in the waste gas, FeMn / TiO2 catalysts can be poisoned within a short period, leading to a decrease in the conversion rate of NOx. Therefore, there is an urgent need to improve the sulfur resistance of FeMn / TiO2 catalysts for treating NOx-containing waste gas. Summary of the Invention

[0003] The purpose of this invention is to provide a waste gas treatment method that can efficiently treat waste gases including nitrogen oxides and sulfur-containing gases.

[0004] The technical solution of the present invention is as follows:

[0005] A method for treating waste gas, the waste gas comprising nitrogen oxides and sulfur-containing gases, the method comprising reducing the nitrogen oxides with RuFeMn / TiO2, wherein the RuFeMn / TiO2 is prepared by the following method:

[0006] Iron precursor Fe(NO3)3·9H2O, manganese precursor Mn(NO3)2·4H2O, and ruthenium precursor RuCl3·3H2O were added to deionized water and stirred for 15-20 min to ensure thorough mixing. Then, TiO2 support was added to the precursor solution, and the mixture was stirred at 300-400 r / min for 3-5 h at 75-78 °C. Ammonia was added to adjust the pH to 9.2-9.6, followed by vacuum filtration. Dry at 120-130℃, and finally sinter in air at 550-580℃ for 4-5 hours. After cooling to room temperature, press, grind and sieve to obtain 80-120 mesh RuFeMn / TiO2 powder. By adjusting the amount of raw materials, the molar ratio of Ru, Fe, Mn and Ti in RuFeMn / TiO2 is (0.08-0.33):(1-1.2):(4-4.5):(8-9).

[0007] Preferably, the pH is 9.6.

[0008] Preferably, the drying temperature is 120°C.

[0009] Preferably, the sintering temperature is 580°C.

[0010] Preferably, the sintering time is 5 hours.

[0011] Preferably, the molar ratio of Ru, Fe, Mn, and Ti in the RuFeMn / TiO2 is 0.25:1:4:8.

[0012] This invention provides a waste gas treatment method that can efficiently treat waste gases including nitrogen oxides and sulfur-containing gases. To treat nitrogen oxides in the waste gas, the addition of ruthenium to the FeMn / TiO2 catalyst significantly improves its sulfur resistance. When the molar ratio of Ru to Fe in the RuFeMn / TiO2 catalyst is 0.08-0.33:1, the initial NO conversion rate and the NO conversion rate after 5 hours both exceed 80%, indicating that the catalyst possesses good denitrification and sulfur resistance performance, meeting the treatment requirements for nitrogen oxide waste gas. Detailed Implementation

[0013] The technical effects of the present invention will be verified through specific embodiments below, but the implementation of the present invention is not limited thereto.

[0014] Example 1

[0015] Iron precursor (Fe(NO3)3·9H2O), manganese precursor (Mn(NO3)2·4H2O), and ruthenium precursor (RuCl3·3H2O) were added to deionized water and stirred for 15 min to ensure thorough mixing. Then, TiO2 support was added to the precursor solution, and the mixture was stirred at 300 r / min for 3 h at 78 °C. Ammonia was added to adjust the pH to 9.6, followed by vacuum filtration and drying at 120 °C. Finally, the mixture was sintered in air at 550 °C for 5 h. After cooling to room temperature, the mixture was pressed into tablets, ground, and sieved to obtain an 80-120 mesh RuFeMn / TiO2 catalyst. By adjusting the amount of raw materials, the molar ratio of Ru, Fe, Mn, and Ti in the RuFeMn / TiO2 catalyst was made to be 0.08:1:4:8.

[0016] Example 2

[0017] Iron precursor (Fe(NO3)3·9H2O), manganese precursor (Mn(NO3)2·4H2O), and ruthenium precursor (RuCl3·3H2O) were added to deionized water and stirred for 15 min to ensure thorough mixing. Then, TiO2 support was added to the precursor solution, and the mixture was stirred at 300 r / min for 3 h at 78 °C. Ammonia was added to adjust the pH to 9.6, followed by vacuum filtration and drying at 120 °C. Finally, the mixture was sintered in air at 550 °C for 5 h. After cooling to room temperature, the mixture was pressed into tablets, ground, and sieved to obtain an 80-120 mesh RuFeMn / TiO2 catalyst. By adjusting the amount of raw materials, the molar ratio of Ru, Fe, Mn, and Ti in the RuFeMn / TiO2 catalyst was made to be 0.13:1:4:8.

[0018] Example 3

[0019] Iron precursor (Fe(NO3)3·9H2O), manganese precursor (Mn(NO3)2·4H2O), and ruthenium precursor (RuCl3·3H2O) were added to deionized water and stirred for 15 min to ensure thorough mixing. Then, TiO2 support was added to the precursor solution, and the mixture was stirred at 300 r / min for 3 h at 78 °C. Ammonia was added to adjust the pH to 9.6, followed by vacuum filtration and drying at 120 °C. Finally, the mixture was sintered in air at 550 °C for 5 h. After cooling to room temperature, the mixture was pressed into tablets, ground, and sieved to obtain an 80-120 mesh RuFeMn / TiO2 catalyst. By adjusting the amount of raw materials, the molar ratio of Ru, Fe, Mn, and Ti in the RuFeMn / TiO2 catalyst was made to be 0.19:1:4:8.

[0020] Example 4

[0021] Iron precursor (Fe(NO3)3·9H2O), manganese precursor (Mn(NO3)2·4H2O), and ruthenium precursor (RuCl3·3H2O) were added to deionized water and stirred for 15 min to ensure thorough mixing. Then, TiO2 support was added to the precursor solution, and the mixture was stirred at 300 r / min for 3 h at 78 °C. Ammonia was added to adjust the pH to 9.6, followed by vacuum filtration and drying at 120 °C. Finally, the mixture was sintered in air at 550 °C for 5 h. After cooling to room temperature, the mixture was pressed into tablets, ground, and sieved to obtain an 80-120 mesh RuFeMn / TiO2 catalyst. By adjusting the amount of raw materials, the molar ratio of Ru, Fe, Mn, and Ti in the RuFeMn / TiO2 catalyst was made to be 0.25:1:4:8.

[0022] Example 5

[0023] Iron precursor (Fe(NO3)3·9H2O), manganese precursor (Mn(NO3)2·4H2O), and ruthenium precursor (RuCl3·3H2O) were added to deionized water and stirred for 15 min to ensure thorough mixing. Then, TiO2 support was added to the precursor solution, and the mixture was stirred at 300 r / min for 3 h at 78 °C. Ammonia was added to adjust the pH to 9.6, followed by vacuum filtration and drying at 120 °C. Finally, the mixture was sintered in air at 550 °C for 5 h. After cooling to room temperature, the mixture was pressed into tablets, ground, and sieved to obtain an 80-120 mesh RuFeMn / TiO2 catalyst. By adjusting the amount of raw materials, the molar ratio of Ru, Fe, Mn, and Ti in the RuFeMn / TiO2 catalyst was made to be 0.33:1:4:8.

[0024] Comparative Example 1

[0025] Iron precursor (Fe(NO3)3·9H2O) and manganese precursor (Mn(NO3)2·4H2O) were added to deionized water and stirred for 15 min to ensure thorough mixing. Then, TiO2 support was added to the precursor solution and stirred at 300 r / min for 3 h at 78 °C. Ammonia was added to adjust the pH to 9.6. The solution was then vacuum filtered and dried at 120 °C. Finally, it was sintered in air at 550 °C for 5 h. After cooling to room temperature, the solution was pressed into tablets, ground, and sieved to obtain an 80-120 mesh FeMn / TiO2 catalyst. By adjusting the amount of raw materials, the molar ratio of Fe, Mn, and Ti in the FeMn / TiO2 catalyst was made to be 1:4:8.

[0026] Comparative Example 2

[0027] Iron precursor (Fe(NO3)3·9H2O), manganese precursor (Mn(NO3)2·4H2O), and ruthenium precursor (RuCl3·3H2O) were added to deionized water and stirred for 15 min to ensure thorough mixing. Then, TiO2 support was added to the precursor solution, and the mixture was stirred at 300 r / min for 3 h at 78 °C. Ammonia was added to adjust the pH to 9.6, followed by vacuum filtration and drying at 120 °C. Finally, the mixture was sintered in air at 550 °C for 5 h. After cooling to room temperature, the mixture was pressed into tablets, ground, and sieved to obtain an 80-120 mesh RuFeMn / TiO2 catalyst. By adjusting the amount of raw materials, the molar ratio of Ru, Fe, Mn, and Ti in the RuFeMn / TiO2 catalyst was made to be 0.6:1:4:8.

[0028] Next, we evaluated the catalytic and sulfur resistance performance of the samples in Examples 1-5 and Comparative Examples 1-2 at a test temperature of 100°C. The catalytic performance was evaluated by introducing a simulated waste gas containing 800 ppm NO, 300 ppm NH3, 6% O2, 10% H2O, and 84% N2 (concentrations here are volume concentrations, and the volume percentage of the simulated waste gas occupied by NO and NH3 is ignored). The catalytic performance was evaluated based on the NO conversion rate in the simulated waste gas. For sulfur resistance evaluation, 100 ppm SO2 was introduced into the simulated waste gas, and the sulfur resistance performance was evaluated based on the NO conversion rate 5 hours after SO2 introduction. The test results are shown in Table 1.

[0029] Table 1 Test data for each sample

[0030] Example 1 87.7 80.1 Example 2 89.3 85.6 Example 3 95.2 86.7 Example 4 >99.9 92.2 Example 5 91.2 83.2 Comparative Example 1 85.6 13.1 Comparative Example 2 81.6 68.9

[0031] As shown in Table 1, the addition of ruthenium to the FeMn / TiO2 catalyst significantly improves its sulfur resistance. When the molar ratio of Ru to Fe in the RuFeMn / TiO2 catalyst is 0.08-0.33:1, the initial NO conversion rate and the NO conversion rate after 5 hours in the exhaust gas both exceed 80%, indicating that the catalyst has good denitrification and sulfur resistance performance.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for treating waste gas, wherein the waste gas comprises nitrogen oxides and sulfur-containing gases, characterized in that, The waste gas treatment method includes reducing the nitrogen oxides with RuFeMn / TiO2, wherein RuFeMn / TiO2 is prepared by the following method: Iron precursor Fe(NO3)3·9H2O, manganese precursor Mn(NO3)2·4H2O, and ruthenium precursor RuCl3·3H2O were added to deionized water and stirred for 15-20 min to ensure thorough mixing. Then, TiO2 support was added to the precursor solution, and the mixture was stirred at 300-400 r / min for 3-5 h at 75-78 °C. Ammonia was added to adjust the pH to 9.2-9.6, followed by vacuum filtration. Dry at 120-130℃, and finally sinter in air at 550-580℃ for 4-5 hours. After cooling to room temperature, press, grind and sieve to obtain 80-120 mesh RuFeMn / TiO2 powder. By adjusting the amount of raw materials, the molar ratio of Ru, Fe, Mn and Ti in RuFeMn / TiO2 is (0.13-0.33):(1-1.2):(4-4.5):(8-9).

2. A waste gas treatment method as described in claim 1, characterized in that, The pH value is 9.

6.

3. A waste gas treatment method as described in claim 1, characterized in that, The drying temperature is 120°C.

4. A waste gas treatment method as described in claim 1, characterized in that, The sintering temperature is 580℃.

5. A waste gas treatment method as described in claim 1, characterized in that, The sintering time is 5 hours.

6. A waste gas treatment method as described in claim 1, characterized in that, The molar ratio of Ru, Fe, Mn, and Ti in the RuFeMn / TiO2 is 0.25:1:4:8.