Catalyst for removing carbon monoxide in dry quenching recycle gas as well as preparation method and application of catalyst
The Fe-Ce/Pd or Mn-Ce/Pd type catalyst prepared by the impregnation method solves the problem of low CO removal efficiency under complex flue gas atmosphere, and achieves an efficient and low-cost CO removal effect. The catalyst activity and sulfur resistance have also been significantly improved.
Patent Information
- Application Number
- CN202510050003.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-13
- Publication Date
- 2025-04-22
AI Technical Summary
The prior art is difficult to effectively and stably remove high concentrations of carbon monoxide (CO) in the dry quenching circulation gas under complex flue gas atmospheres, resulting in low treatment efficiency and high cost.
A metal-supported catalyst was prepared by the impregnation method, and the Fe-Ce/Pd type or Mn-Ce/Pd type catalyst was prepared by the interaction of the porous support and the metal salt aqueous solution, and contacted with the CO-enriched gas under the conditions of 360°C to 500°C to achieve efficient removal of CO.
The catalyst's CO removal rate in the dry quenching circulation gas reaches more than 90%, and has good sulfur resistance and stability. The catalyst activity remains above 98%, which significantly improves the CO conversion rate.
Smart Images
Figure BDA0005239698730000061 
Figure BDA0005239698730000071 
Figure BDA0005239698730000072
Abstract
Description
Technical Field
[0001] The invention belongs to the field of catalysts, and in particular relates to a catalyst for removing carbon monoxide from dry quenching circulating gas, and a preparation method and application thereof. Background Art
[0002] In recent years, with the continuous deepening of air pollution prevention and control work in my country, conventional air pollutants have been effectively controlled and environmental quality has been improved. At the same time, the emission of some unconventional pollutants (such as CO, ammonia escape, VOCs, etc.) has gradually attracted attention. Among them, carbon monoxide (CO) has become the focus of attention because it can easily combine with hemoglobin in the blood that carries oxygen. At low concentrations, it can cause hypoxia damage to humans or animals, causing dizziness and headaches in mild cases, permanent damage to brain cells in severe cases, and even suffocation and death.
[0003] my country is the largest producer of steel. Coal is used in the coking and sintering process in the steel industry. The flue gas discharged from the coke oven and sintering machine contains a high concentration of carbon monoxide (CO). For example, the CO content in the flue gas of the coke oven can reach up to 4000-6000ppm, the CO content in the flue gas of the sintering machine is as high as 8000-10000ppm, and the CO content in the flue gas of the dry quenching coke oven is as high as 60000-100000ppm. Efficient treatment of high concentrations of CO in flue gas has both energy-saving and environmental protection significance. On the one hand, eliminating CO can meet environmental protection requirements and reduce the emission of atmospheric pollutants CO; on the other hand, the flue gas volume of these industrial kilns is huge, and the treatment and utilization of CO can significantly recover energy. CO catalytic combustion is the main solution to control CO pollutants in flue gas, but there is no mature flue gas CO treatment technology at home and abroad. The main reason is that the stability of the catalyst in a complex flue gas atmosphere has not been solved. It is necessary to develop new high-efficiency and low-cost flue gas CO removal catalysts and removal processes.
[0004] With the development of coking technology, the quenching process of coking production is currently equipped with dry quenching equipment. After the red coke is loaded into the dry quenching furnace, the remaining hydrogen, methane, carbon monoxide in the red coke and the carbon monoxide generated by the reaction of the remaining carbon dioxide with the red coke in the high temperature zone all enter the dry quenching circulation system, posing an explosion risk. In order to achieve the safe operation of the dry quenching gas circulation system, part of the circulating gas is usually released after the circulating fan. This part of the released gas contains 6% CO and a small amount of combustible gases such as H2, which are currently discharged directly into the atmosphere without treatment. my country is a major producer of coke. According to estimates, the amount of CO released by the dry quenching section of coking enterprises across the country is as high as 5 to 8 million tons each year. The treatment and utilization of these CO will produce significant energy-saving benefits. Summary of the invention
[0005] Regarding the above technical issues:
[0006] The main purpose of the present invention is to provide a catalyst which can effectively reduce the content of CO in the dry quenching circulating gas.
[0007] Another object of the present invention is to provide a method for preparing the above catalyst, which is simple, convenient and easy to operate.
[0008] Another object of the present invention is to provide the use of the above catalyst in removing CO from dry quenching circulating gas.
[0009] To achieve the above object, on the one hand, the present invention provides a method for preparing a catalyst, the method comprising the following steps:
[0010] 1) After pre-treatment by drying, the porous carrier is directly impregnated with a metal salt aqueous solution, wherein the metal salt aqueous solution comprises ① Ce(NO3)3 and ② Fe(NO3)3 and / or Mn(NO3)2 as main catalyst precursors, and comprises one selected from palladium chloride and platinum chloride as a co-catalyst precursor;
[0011] 2) Drying and calcining the catalyst impregnated with the aqueous metal salt solution to obtain a metal-supported catalyst.
[0012] In a specific embodiment, in step 1), the porous carrier is cordierite, and its specific surface area is 450m 2 / g, pore volume is 0.22cm 3 / g.
[0013] In a specific embodiment, in step 1), the porous support is not surface modified.
[0014] In a specific embodiment, in step 1), the drying pretreatment refers to drying the cordierite carrier at 100-200° C. for 24 hours.
[0015] In a specific embodiment, in step 1), based on the total weight of the catalyst carrier, the loading amount of the main catalyst is 3-5% (calculated as metal), and the loading amount of the co-catalyst is 0.1-0.3% (calculated as metal).
[0016] In a specific embodiment, in step 1), based on the total weight of the catalyst carrier, the active components Fe, Ce and Mn in the main catalyst are loaded in amounts of 1.5-2.0%, 0.3-0.5% and 1.5-2.5%, respectively, and the active component of the co-catalyst is Pd, and its loading amount is 0.1-0.3%.
[0017] In a specific embodiment, in step 2), the catalyst immersed in the metal salt aqueous solution for more than 48 hours is dried at 50-100°C for 1-5 hours, then dried at 100-200°C for 2-5 hours, and then calcined at 300-800°C for 2-8 hours, with the heating rate controlled at 1-10°C / min to obtain a metal-supported catalyst.
[0018] In another aspect, the present invention provides a catalyst prepared by the above method.
[0019] In still another aspect, the present invention provides a method for removing CO, comprising contacting the above catalyst with a gas containing CO.
[0020] In a specific embodiment, the gas containing CO includes flue gas discharged from coke ovens and sintering machines, dry quenching coke oven flue gas, and dry quenching coke circulating exhaust gas.
[0021] In a specific embodiment, the gas containing CO is heated at 360°C-500°C and at a space velocity of 1800-5000h -1 When it comes into contact with the above-mentioned catalyst, the CO therein is catalytically converted into CO2.
[0022] The principle of CO removal from the exhaust gas of CDQ cycle is catalytic combustion reaction. On the surface of the catalyst, CO and H2 undergo oxidation reaction at a lower temperature and are converted into CO2 and H2O, while releasing heat:
[0023] 2H2+O2=2H2O、2CO+O2=2CO2
[0024] Beneficial Effects
[0025] 1) The present application adopts an impregnation method, utilizing the interaction between the characteristics of a porous carrier and metal ions, and directly adds a metal salt aqueous solution to the catalyst carrier during the catalyst preparation process to prepare the catalyst by direct impregnation. The preparation process is simple and reliable.
[0026] 2) The catalyst prepared by the impregnation method was used in the treatment of CO in the CDQ circulating gas, and the CO removal rate reached more than 90%. Moreover, the gas space velocity was maintained at 3038h -1 The catalyst has a certain sulfur resistance at different sulfur concentrations, and the catalyst activity is over 98%.
[0027] 3) Develop a new type of high-efficiency, low-cost flue gas CO removal catalyst and removal process. The catalyst prepared with Fe as the active component can significantly improve the CO conversion rate. Adding an appropriate amount of Mn to increase the surface alkalinity of the catalyst can further optimize the performance of the catalyst, increase the CO conversion rate, and promote the dissociative adsorption of CO, thereby increasing the CO conversion rate. Adding an appropriate amount of Ce components can often improve the activity, selectivity and stability of the catalyst in the catalytic reaction. DETAILED DESCRIPTION
[0028] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.
[0029] Materials and reagents
[0030] Reagents: Fe(NO3)3 (Tianjin Damao), Ce(NO3)3 (Tianjin Damao), Mn(NO3)2 (Tianjin Damao), PdCl2 (Tianjin Damao)
[0031] Materials: Cordierite carrier (200 mesh) (Tianma Industrial Ceramics, Pingxiang, Jiangxi Province), the main components are 40-50% alumina, 35-45% silicon dioxide, and 5-10% magnesium oxide. The cordierite carrier has a density of 2.2, a thermal expansion coefficient of 6, a specific heat of 1000, a thermal conductivity of 1.5-2.5, a thermal shock strength of >350, a softening temperature of 1250°C, a Y strength of 40-50, and an X strength of 15-45.
[0032] CO determination method: Use Testo 310 to detect the inlet and outlet CO concentration.
[0033] Example 1
[0034] 80 g of cordierite carrier was dried at 100-200° C. for 24 hours, and then immersed in a mixed solution of noble metal, non-noble metal and rare metal salts, wherein the noble metal salt was palladium chloride, Pd 2+ The concentration is 2g / L, and the rare metal salt is cerium nitrate, Ce 2+ The concentration is 25g / L, the non-precious metal salt is ferric nitrate, Fe 3+ The concentration is 30g / L. Immerse in the metal active solution for 48h. After forced air drying at 100℃ for 1h and at 200℃ for 2h, calcinate at 360℃ for 2h, and control the heating rate at 1-10℃ / min to obtain Fe-Ce / Pd type metal catalyst.
[0035] Example 2
[0036] 80 g of cordierite carrier was dried at 100-200° C. for 24 hours, and then immersed in a mixed solution of noble metal, non-noble metal and rare metal salts, wherein the noble metal salt was palladium chloride, Pd 2+The concentration is 2g / L, and the rare metal salt is cerium nitrate, Ce 2+ The concentration of is 25g / L, the non-precious metal salt is manganese nitrate, and the concentration of Mn is 30g / L. The impregnation time is 48 hours, and after being dried at 100℃ for 1 hour and 200℃ for 2 hours, it is calcined at 360℃ for 2 hours, and the heating rate is controlled at 1-10℃ / min to obtain a Mn-Ce / Pd type metal catalyst.
[0037] Example 3
[0038] 80 g of cordierite carrier was dried at 100-200° C. for 24 hours, and then immersed in a mixed solution of noble metal, non-noble metal and rare metal salts, wherein the noble metal salt was palladium chloride, Pd 2+ The concentration is 2g / L, and the rare metal salt is cerium nitrate, Ce 2+ The concentration is 25g / L, and the non-precious metal salts are ferric nitrate, manganese nitrate, Fe 3+ and Mn 2+ The concentration of each was 30 g / L. The impregnation time was 48 hours, and after being dried at 100°C for 1 hour and 200°C for 2 hours, the catalyst was calcined at 360°C for 2 hours, and the heating rate was controlled at 1-10°C / min to obtain a Fe-Mn-Ce / Pd type metal catalyst.
[0039] The catalyst prepared in Example 1-3 was used for the treatment of CO. The catalyst was contacted with a CO-containing gas at 260-450°C and a space velocity of 2000 h -1 -5000h -1 Under the conditions of catalytic oxidation, CO is catalytically oxidized to produce CO2.
[0040] The test results are shown in Table 1. CO is 10% gas, N2 is the balance gas, the reaction temperature is 260°C, and the gas space velocity is 2000h -1 .
[0041] Table 1 Catalytic efficiency of CO catalysis by different catalysts
[0042] catalyst Temperature / ℃ airspeed Outlet CO concentration / ppm Inlet CO concentration / ppm Conversion Rate % Example 1 260 2000 18000 50000 64 Example 2 260 2000 20000 50000 60 Example 3 260 2000 2800 50000.0 94.5
[0043] It can be seen from the data in Table 1 that Fe and Mn have an important influence on the catalytic efficiency of the catalyst for CO. The catalytic efficiency of the catalysts prepared in Example 1 (containing only Fe) and 2 (containing only Mn) is only about 60%, and the CO catalytic conversion rate of the catalyst prepared in Example 3 (containing both Fe and Mn) reaches 94.5%.
[0044] The catalyst prepared in Example 3 was subjected to a CO catalytic oxidation conversion test at different space velocities. The test data are shown in Table 2 below:
[0045] Table 2 CO removal efficiency at different space velocities
[0046]
[0047]
[0048] As shown in Table 2, the catalyst prepared in Example 3 was tested at different gas space velocities, with the gas space velocity ranging from 1899 h -1 Increased to 4937h -1 , the CO catalytic conversion rate can reach over 92%.
[0049] Table 3 CO conversion rate at different temperatures
[0050]
[0051] As shown in Table 3, the catalyst prepared in Example 3 was tested at different temperatures, and the gas space velocity was maintained at 3038h -1 , With the increase of temperature, the CO removal efficiency increases, and the removal efficiency reaches 98.5% at 500℃.
[0052] Table 4 Catalyst sulfur resistance test
[0053]
[0054] As shown in Table 4, the catalyst prepared in Example 3 was tested at different sulfur contents, the temperature was 260°C, and the gas space velocity was maintained at 3038h -1 The catalyst has a certain sulfur resistance at different sulfur concentrations, and the catalyst activity is over 98%.
Claims
1. A method for preparing a catalyst, the method comprising the following steps: 1) After the porous carrier is dried and pretreated, it is directly impregnated with a metal salt aqueous solution, wherein the metal salt aqueous solution contains ① Ce(NO3)3 and ② Fe(NO3)3 and / or Mn(NO3)2 as main catalyst precursors; and contains one selected from palladium chloride and platinum chloride as a co-catalyst precursor; as well as 2) Drying and calcining the catalyst impregnated with the aqueous metal salt solution to obtain a metal-supported catalyst.
2. The method according to claim 1, wherein: In step 1), the porous carrier is cordierite, and its specific surface area is 450m 2 / g, pore volume is 0.22cm 3 / g.
3. The method according to claim 1, wherein: In step 1), the porous support is not surface-modified.
4. The method according to claim 2, wherein: In step 1), the drying pretreatment refers to drying the cordierite carrier at 100-200° C. for 24 hours.
5. The method according to claim 1, wherein: In step 1), based on the total weight of the catalyst carrier, the loading amount of the main catalyst is 3-5%, and the loading amount of the co-catalyst is 0.1-0.3%. Preferably, the active components in the main catalyst are Fe, Ce and Mn, and their loading amounts are 1.5-2%, 0.3-0.5%, and 1.5-2.5%, respectively. The active component of the co-catalyst is Pd, and its loading amount is 0.1-0.3%.
6. The method according to claim 1, wherein in step 2), the catalyst immersed in the metal salt aqueous solution for more than 48 hours is dried at 50-100°C for 1-5 hours, then dried at 100-200°C for 2-5 hours, and then calcined at 300-800°C for 2-8 hours, with the heating rate controlled at 1-10°C / min to obtain a metal-supported catalyst.
7. A catalyst prepared by the method according to any one of claims 1 to 6.
8. A method for removing CO, the method comprising contacting the catalyst according to claim 7 with a gas containing CO.
9. The method according to claim 8, wherein: The gas containing CO includes flue gas discharged from coke ovens and sintering machines, dry quenching coke oven flue gas, and dry quenching coke circulating exhaust gas.
10. The method according to claim 8, wherein: The gas containing CO is heated at 360°C-500°C and at a space velocity of 1800-5000 h -1 The gas is contacted with the catalyst to catalytically convert the CO therein into CO2.