Sulfur-resistant wear-resistant denitration catalyst, preparation method and application thereof
By preparing cerium-zirconium composite oxides and catalysts combining Cr2O3/Al2O3 wear-resistant particles with titanium dioxide sol, the problem of reduced activity of denitrification catalysts under high sulfur and wear environments was solved, achieving excellent sulfur resistance, wear resistance, and efficient denitrification effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING TECH UNIV
- Filing Date
- 2024-08-16
- Publication Date
- 2026-07-24
AI Technical Summary
Existing denitrification catalysts are prone to clogging and wear in the presence of high dust and sulfur oxides, resulting in reduced activity and shortened service life.
A cerium-zirconium composite oxide was prepared by reacting a mixture of cerium and zirconium salts with ammonia water. This oxide, combined with Cr2O3/Al2O3 wear-resistant particles and titanium dioxide sol, forms a stable solid solution structure, thereby improving the catalyst's sulfur resistance and wear resistance.
It maintains high denitrification activity and stability under high sulfur and abrasion conditions, with an abrasion rate of less than 0.06%/kg, thus extending the catalyst's service life.
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Figure CN119034717B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a sulfur-resistant and wear-resistant denitrification catalyst, its preparation method and application, belonging to the field of catalyst and its preparation technology. Background Technology
[0002] In the current field of environmental protection technology, denitrification catalysts are key materials for reducing nitrogen oxide (NOx) emissions, and their performance directly affects the efficiency and stability of flue gas purification systems. In actual flue gas environments, even after desulfurization treatment, small amounts of SO2 may still be present. This SO2 reacts with NH3 to form ammonium sulfate, which coats the catalyst surface and blocks the catalyst pores. When H2O is also present in the flue gas, water vapor further promotes the deposition of ammonium sulfate on the catalyst surface, further exacerbating the blockage of the catalyst pores, thus significantly reducing the denitrification activity of the catalyst.
[0003] Meanwhile, the flue gas from industries such as cement manufacturing is characterized by high dust concentration, small particle size, and high viscosity, along with a high alkaline content and the presence of various heavy metals. These characteristics pose a severe challenge to the wear resistance of denitrification catalysts. High concentrations of dust particles easily cause erosion and wear on the catalyst surface as they pass through, shortening the catalyst's lifespan.
[0004] Therefore, there is an urgent need for a denitrification catalyst that combines excellent sulfur resistance and excellent wear resistance. Summary of the Invention
[0005] The purpose of this invention is to provide a sulfur-resistant and wear-resistant denitrification catalyst, its preparation method and application. This catalyst has excellent low-temperature sulfur-resistant denitrification performance and excellent wear resistance, which can improve denitrification efficiency and extend the service life of the catalyst.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A method for preparing a sulfur-resistant, wear-resistant, and denitrification catalyst, wherein the preparation method comprises: mixing cerium salt and zirconium salt and adding them to an ammonia solution for reaction; after the reaction, centrifuging, drying, and ball milling to obtain a catalyst precursor; then mixing the catalyst precursor, Cr2O3 / Al2O3 wear-resistant particles, and titanium dioxide sol, and then drying and calcining to obtain the sulfur-resistant, wear-resistant, and denitrification catalyst.
[0008] Preferably, the cerium salt is cerium nitrate; the zirconium salt is zirconium nitrate; and the molar ratio of cerium to zirconium in the cerium salt and zirconium salt is 1:(3-9).
[0009] Preferably, the drying conditions are: 85-100℃, 5-20h.
[0010] Preferably, the preparation method of Cr2O3 / Al2O3 wear-resistant particles is as follows: Al2O3 powder is added to deionized water containing Cr(NO3)3·9H2O, sodium hydroxide solution is added under stirring, and after no precipitate is formed, the supernatant is removed by standing, and then filtered, washed, dried and calcined to obtain Cr2O3 / Al2O3 wear-resistant particles.
[0011] Preferably, the mass ratio of Al2O3 powder to Cr(NO3)3·9H2O is (5-8):(2-3);
[0012] The drying conditions are: under vacuum, 100-130℃, for 10-15 hours;
[0013] The calcination conditions are: 400-550℃, 1.5-3h.
[0014] Preferably, the preparation method of titanium dioxide sol is as follows: tetrabutyl titanate, anhydrous ethanol and glacial acetic acid are mixed evenly in a mass ratio of (5-7):(8-11):(12-16) to obtain solution A; anhydrous ethanol, glacial acetic acid and deionized water are mixed evenly in a mass ratio of (4-7):(1-3):(1-2) to obtain solution B; under stirring, solution B is gradually added to solution A to obtain titanium dioxide sol.
[0015] Preferably, the mass ratio of titanium dioxide sol, Cr2O3 / Al2O3 wear-resistant particles and catalyst precursor is (70-85):(7-15):(6-13).
[0016] Preferably, the drying conditions are: 100-150℃, 2-5h;
[0017] The calcination conditions are: 400-750℃, 2-6h.
[0018] A sulfur-resistant and wear-resistant denitrification catalyst is prepared by any of the methods described above.
[0019] The sulfur-resistant and wear-resistant denitrification catalyst prepared by any of the above methods in NO x Applications in removal.
[0020] The beneficial effects of this invention are as follows:
[0021] This catalyst maintains high denitrification activity at 200-250℃ under sulfur-water conditions, with the highest denitrification efficiency at 200℃. Furthermore, due to the doping of Cr2O3 / Al2O3 wear-resistant particles, the catalyst exhibits excellent wear resistance; when tested using the method for measuring the wear rate of honeycomb flue gas denitrification catalysts, the wear rate is only 0.06% / kg. Attached Figure Description
[0022] Figure 1 The graph shows the denitrification reaction activity test results of the sulfur-resistant and wear-resistant denitrification catalysts prepared in Example 1, Comparative Examples 1 and 2.
[0023] Figure 2 The graph shows the water and sulfur resistance stability test results of the anti-sulfur and wear-resistant denitrification catalysts prepared in Example 1, Comparative Examples 1 and 2. Detailed Implementation
[0024] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0025] Example 1
[0026] 5g of Ce(NO3)3 and 58.2g of Zr(NO3)4 were mixed with water to prepare a 200ml mixed solution. The mixed solution was slowly added dropwise to 100ml of 20% ammonia water. After the addition was complete, the mixture was stirred at 45℃ under aeration for 2 hours to obtain a yellow suspension. The suspension was centrifuged, filtered, dried at 90℃ for 5 hours, pulverized, and sieved to obtain 150-250 mesh cerium-zirconium composite oxide particles.
[0027] Tetrabutyl titanate, anhydrous ethanol, and glacial acetic acid were mixed in a mass ratio of 7:11:14 and stirred at 500 rpm for 1 hour to obtain solution A. Anhydrous ethanol, glacial acetic acid, and deionized water were mixed in a mass ratio of 4:2:1 and stirred at 300 rpm for 1 hour to obtain solution B. Solution B was added to solution A at a volume ratio of 1:1 and at 300 rpm. After the addition was complete, the stirring speed was adjusted to 1000 rpm, and the mixture was stirred for 3 hours and then allowed to stand for aging to obtain titanium dioxide sol.
[0028] According to the mass ratio of Al2O3 powder:(Cr(NO3)3·9H2O)=7:3, Al2O3 powder was added to deionized water containing Cr(NO3)3·9H2O. Sodium hydroxide solution was added while stirring. After no precipitate was formed, the supernatant was removed by standing. After filtration and washing, the powder was dried at 100℃ for 12 hours under vacuum and then calcined at 450℃ for 2 hours to obtain Cr2O3 / Al2O3 wear-resistant particles.
[0029] Take 30g of cerium-zirconium composite oxide particles and 40g of Cr2O3 / Al2O3 wear-resistant particles, mix them with 375g of titanium dioxide sol at 500rpm for 5h, dry them at 120℃ for 5h, and then calcine them in a muffle furnace at 550℃ for 3h to obtain the catalyst.
[0030] Comparative Example 1
[0031] It is basically the same as Example 1, except that no Cr2O3 / Al2O3 wear-resistant particles were added in Comparative Example 1.
[0032] Specifically:
[0033] 5g of Ce(NO3)3 and 58.2g of Zr(NO3)4 were mixed with water to prepare a 200ml mixed solution. The mixed solution was slowly added dropwise to 100ml of 20% ammonia water. After the addition was complete, the mixture was stirred at 45℃ under aeration for 2 hours to obtain a yellow suspension. The suspension was centrifuged, filtered, dried at 90℃ for 5 hours, pulverized, and sieved to obtain 150-250 mesh cerium-zirconium composite oxide particles.
[0034] Tetrabutyl titanate, anhydrous ethanol, and glacial acetic acid were mixed in a mass ratio of 7:11:14 and stirred at 500 rpm for 1 hour to obtain solution A. Anhydrous ethanol, glacial acetic acid, and deionized water were mixed in a mass ratio of 4:2:1 and stirred at 300 rpm for 1 hour to obtain solution B. Solution B was added to solution A at a volume ratio of 1:1 and at 300 rpm. After the addition was complete, the stirring speed was adjusted to 1000 rpm, and the mixture was stirred for 3 hours and then allowed to stand for aging to obtain titanium dioxide sol.
[0035] According to the mass ratio of Al2O3 powder:(Cr(NO3)3·9H2O)=7:3, Al2O3 powder was added to deionized water containing Cr(NO3)3·9H2O. Sodium hydroxide solution was added while stirring. After no precipitate was formed, the supernatant was removed by standing. After filtration and washing, the powder was dried at 100℃ for 12 hours under vacuum and then calcined at 450℃ for 2 hours to obtain Cr2O3 / Al2O3 wear-resistant particles.
[0036] Take 30g of cerium-zirconium composite oxide particles, mix them with 375g of titanium dioxide sol at 500rpm for 5h, dry them at 120℃ for 5h, and then calcine them in a muffle furnace at 550℃ for 3h to obtain the catalyst.
[0037] Comparative Example 2
[0038] It is basically the same as Example 1, except that the amount of Cr2O3 / Al2O3 wear-resistant particles added in Comparative Example 2 is lower than that in Example 1.
[0039] Specifically:
[0040] 5g of Ce(NO3)3 and 58.2g of Zr(NO3)4 were mixed with water to prepare a 200ml mixed solution. The mixed solution was slowly added dropwise to 100ml of 20% ammonia water. After the addition was complete, the mixture was stirred at 45℃ under aeration for 2 hours to obtain a yellow suspension. The suspension was centrifuged, filtered, dried at 90℃ for 5 hours, pulverized, and sieved to obtain 150-250 mesh cerium-zirconium composite oxide particles.
[0041] Tetrabutyl titanate, anhydrous ethanol, and glacial acetic acid were mixed in a mass ratio of 7:11:14 and stirred at 500 rpm for 1 hour to obtain solution A. Anhydrous ethanol, glacial acetic acid, and deionized water were mixed in a mass ratio of 4:2:1 and stirred at 300 rpm for 1 hour to obtain solution B. Solution B was added to solution A at a volume ratio of 1:1 and at 300 rpm. After the addition was complete, the stirring speed was adjusted to 1000 rpm, and the mixture was stirred for 3 hours and then allowed to stand for aging to obtain titanium dioxide sol.
[0042] According to the mass ratio of Al2O3 powder:(Cr(NO3)3·9H2O)=7:3, Al2O3 powder was added to deionized water containing Cr(NO3)3·9H2O. Sodium hydroxide solution was added while stirring. After no precipitate was formed, the supernatant was removed by standing. After filtration and washing, the powder was dried at 100℃ for 12 hours under vacuum and then calcined at 450℃ for 2 hours to obtain Cr2O3 / Al2O3 wear-resistant particles.
[0043] Take 30g of cerium-zirconium composite oxide particles and 10g of Cr2O3 / Al2O3 wear-resistant particles, mix them with 375g of titanium dioxide sol at 500rpm for 5h, dry them at 120℃ for 5h, and then calcine them in a muffle furnace at 550℃ for 3h to obtain the catalyst.
[0044] Denitrification reaction activity test: The denitrification performance of the catalyst was tested using simulated flue gas. The simulated flue gas composition was: NO: 500 ppm, NH3: 500 ppm, O2: 5%, N2 as the balance gas, and the space velocity was 30,000 h⁻¹. -1 The flue gas flow rate was 300 ml / min. The same volume of catalyst was placed in a fixed bed reactor for testing. The denitrification efficiency of the catalyst at different temperatures was tested, and the reaction temperature was controlled between 150 and 350 ℃.
[0045] Water and sulfur resistance stability test: The catalyst denitrification performance was tested using simulated flue gas. The simulated flue gas composition was: NO: 500ppm, NH3: 500ppm, O2: 5%, H2O: 3%, SO2: 100ppm, with N2 as the balance gas, and a space velocity of 30,000 h⁻¹. -1The flue gas flow rate was 300 ml / min. The same volume of catalyst was placed in a fixed bed reactor for testing. The denitrification efficiency of the catalyst at different temperatures was tested, and the reaction temperature was controlled between 150 and 300 ℃.
[0046] The sulfur-resistant and wear-resistant denitrification catalysts prepared in Examples 1, 1, and 2 were subjected to the above-mentioned denitrification reaction activity and water-sulfur resistance stability tests, respectively. The results are as follows: Figure 1 , 2 As shown.
[0047] Depend on Figure 1 , Figure 2 It can be seen that, in both the denitrification reaction activity and the water and sulfur resistance stability test, the catalysts prepared in Example 1 and Comparative Examples 1-2 maintained high denitrification efficiency. The reason is that the cerium-zirconium composite oxide can form a stable solid solution structure. This structure helps to resist the influence of adverse factors such as high temperature and water vapor, maintain the activity and stability of the catalyst, and make it less likely to react chemically with sulfur, water and other components in the flue gas, thereby reducing the risk of catalyst deactivation.
[0048] Catalyst wear rate test: The wear rate of honeycomb flue gas denitrification catalyst was determined according to the method for determining the wear rate (GB / T31587-2015). The gas flow velocity in the catalyst channels was 14.5 m / s (standard conditions), and the concentration of abrasive (dry 0.300-0.425 mm high-hardness quartz sand) was 50 g / m³. 3 The flushing time is 2 hours.
[0049] The anti-sulfur denitrification catalysts prepared in Example 1, Comparative Examples 1 and 2 were subjected to catalyst wear rate tests, and the results are shown in Table 1.
[0050] Table 1. Results of denitrification catalyst wear rate
[0051] catalyst Wear rate (%) / kg Example 1 0.06 Comparative Example 1 0.27 Comparative Example 2 0.18
[0052] As can be seen from Table 1, the catalyst with Cr2O3 / Al2O3 wear-resistant particles has a lower wear rate. This is because the Cr2O3 / Al2O3 wear-resistant particles, which are fully dispersed in the titanium dioxide support, can resist wear caused by flue gas flow, fly ash impact, etc., and can improve its overall chemical stability and wear resistance, thus extending the service life of the catalyst.
[0053] 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 principle 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 preparing a sulfur-resistant, wear-resistant, and denitrification catalyst, characterized in that, The preparation method is as follows: cerium salt and zirconium salt are mixed and added to an ammonia solution for reaction. After the reaction, the mixture is centrifuged, dried, and ball-milled to obtain a catalyst precursor. The catalyst precursor, Cr2O3 / Al2O3 wear-resistant particles, and titanium dioxide sol are then mixed, dried, and calcined to obtain the sulfur-resistant, wear-resistant, and denitrification catalyst. The preparation method of Cr2O3 / Al2O3 wear-resistant particles is as follows: Al2O3 powder is added to deionized water containing Cr(NO3)3·9H2O, sodium hydroxide solution is added under stirring, and after no precipitate is formed, the supernatant is removed by standing, and then filtered, washed, dried and calcined to obtain Cr2O3 / Al2O3 wear-resistant particles; the mass ratio of Al2O3 powder to Cr(NO3)3·9H2O is (5-8):(2-3); The preparation method of titanium dioxide sol is as follows: tetrabutyl titanate, anhydrous ethanol and glacial acetic acid are mixed evenly in a mass ratio of (5-7):(8-11):(12-16) to obtain solution A; anhydrous ethanol, glacial acetic acid and deionized water are mixed evenly in a mass ratio of (4-7):(1-3):(1-2) to obtain solution B; under stirring, solution B is gradually added to solution A to obtain titanium dioxide sol. The mass ratio of titanium dioxide sol, Cr2O3 / Al2O3 wear-resistant particles and catalyst precursor is (70-85):(7-15):(6-13).
2. The preparation method of the sulfur-resistant and wear-resistant denitrification catalyst according to claim 1, characterized in that, The cerium salt is cerium nitrate; the zirconium salt is zirconium nitrate; and the molar ratio of cerium to zirconium in the cerium salt and zirconium salt is 1:(3-9).
3. The preparation method of the sulfur-resistant and wear-resistant denitrification catalyst according to claim 1, characterized in that, The drying conditions are: 85-100℃, 5-20h.
4. The preparation method of the sulfur-resistant and wear-resistant denitrification catalyst according to claim 1, characterized in that, In the preparation method of Cr2O3 / Al2O3 wear-resistant particles, the drying conditions are: under vacuum, 100-130℃, 10-15h; the calcination conditions are: 400-550℃, 1.5-3h.
5. The preparation method of the sulfur-resistant and wear-resistant denitrification catalyst according to claim 1, characterized in that, After the catalyst precursor, Cr2O3 / Al2O3 wear-resistant particles and titanium dioxide sol are mixed, the drying conditions are: 100-150℃, 2-5h; the calcination conditions are: 400-750℃, 2-6h.
6. A sulfur-resistant and wear-resistant denitrification catalyst, characterized in that, It is prepared by the method described in any one of claims 1-5.
7. The sulfur-resistant and wear-resistant denitrification catalyst prepared by the method according to any one of claims 1-5 in NO x Applications in removal.