Anti-alkali poisoning denitration catalyst as well as preparation method and application thereof

Abstract

The invention provides an anti-alkali poisoning denitration catalyst as well as a preparation method and application thereof. The anti-alkali poisoning denitration catalyst comprises a denitration component and an anti-alkali poisoning component, the denitration component comprises a vanadium-titanium catalyst, the anti-alkali poisoning component comprises a molecular sieve, and the molecular sieve comprises an H-type molecular sieve and / or an ammonium-type molecular sieve. The catalyst provided by the invention comprises a vanadium-titanium catalyst undertaking SCR reaction and a molecular sieve containing alkali metal and / or alkaline earth metal, and the vanadium-titanium catalyst and the molecular sieve are in a tight contact and uniform mixing state. Alkali metal and / or alkaline earth metal deposited on the vanadium-titanium catalyst can be migrated to acid sites of molecular sieve pore channels, so that the alkali resistance of the vanadium-titanium catalyst is improved; in addition, the preparation method provided by the invention is simple, and is especially suitable for the condition that the alkali metal content is relatively high in the ammonia selective reduction denitration process.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental catalysis, and relates to an anti-alkali-poisoning denitration catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] At present, the NH3 selective catalytic reduction of NO x (NH3-SCR) catalyst is mainly a vanadium-titanium catalyst (V2O5 / TiO2) system doped with WO3 or MoO3. This catalyst system has been widely used in the denitration of flue gas from fixed sources. During the denitration process of the V2O5 / WO3(MoO3)-TiO2 catalyst, it will be affected by alkali metals and alkaline earth metals brought by fly ash, resulting in a significant reduction in its catalytic activity. Therefore, the poisoning of the V2O5 / WO3(MoO3)-TiO2 catalyst by alkali (earth) metal elements is an important problem in its practical application.

[0003] Among the alkali (earth) metal elements, K, Na, Ca, and Mg have the greatest influence on the catalyst activity. Taking the K element as an example, 1% of K2O can almost completely deactivate the V2O5 / WO3(MoO3)-TiO2 catalyst (H. Kamata, K. Takahashi, C. U. Ingemar Odenbrand, J. Mol. Catal. A: Chem. 139 (1999) 189-198). In addition, the disadvantage that the V2O5 / WO3(MoO3)-TiO2 catalyst is easily poisoned by alkali metals and deactivated also limits its application in the denitration of flue gas with a high alkali metal content in ash, such as glass furnaces with an extremely high alkali metal content in ash.

[0004] Based on this, CN113797963A discloses a composite denitration powder and a preparation method thereof. The composite denitration powder is obtained by loading a denitration active component and an auxiliary agent on a core-shell structure CHA / AEI molecular sieve modified by a solid superacid and TiO2 as a carrier, wherein the solid superacid is the shell and the CHA / AEI molecular sieve is the core. Through such a structural setting, the alkali-poisoning resistance ability of the catalyst is improved; CN114733513A discloses a flue gas denitration catalyst and a preparation method thereof. The catalyst uses a microsphere with pores on the surface as a carrier, and alternately loads alkaline active centers and acidic active centers in sequence for multiple times, which also achieves the effect of preventing the catalyst from deactivating due to acid-base poisoning.

[0005] However, the above technical solutions all have the problems of complex catalyst structure and cumbersome preparation process, and it is difficult to cope with the situation of high alkali (earth) metal content in ash, which is not conducive to industrial application. Therefore, how to prepare a denitration catalyst with a simple structure and a wide application range is very important for extending the service life of the catalyst and broadening its application objects, and it is an urgent technical problem to be solved at present. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a denitration catalyst resistant to alkali poisoning, and its preparation method and application. The catalyst provided by the present invention comprises a vanadium titanium catalyst for SCR reaction and a molecular sieve containing alkali metals and / or alkaline earth metals, and the two are in a close contact and uniformly mixed state. When the vanadium titanium catalyst is operated in flue gas containing water vapor, the alkali metals and / or alkaline earth metals deposited on the vanadium titanium catalyst can migrate to the acidic sites of the molecular sieve pores, thereby improving the alkali resistance of the vanadium titanium catalyst; and the preparation method provided by the present invention is simple, and is particularly suitable for the case where the alkali metal content is high in the process of selective reduction denitration of ammonia.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an alkali-poisoning resistant denitrification catalyst, which comprises a denitrification component and an alkali-poisoning resistant component, wherein the denitrification component comprises a vanadium-titanium catalyst, and the alkali-poisoning resistant component comprises a molecular sieve, and the molecular sieve comprises an H-type molecular sieve and / or an ammonium-type molecular sieve.

[0009] It should be noted that the vanadium-titanium catalyst in the present invention refers to a catalyst with vanadium and titanium as main active substances, and may also include the case of containing other promoters, such as tungsten or molybdenum, and is not limited to containing only vanadium and titanium.

[0010] In the present invention, the vanadium-titanium catalyst and the molecular sieve are in a tightly combined and uniformly mixed state, and the molecular sieve provides a large number of sites for accommodating alkali metal and / or alkaline earth metal ions. When fly ash containing alkali metals in the flue gas is deposited on the catalyst, the alkali metal and / or alkaline earth metal ions deposited on the vanadium-titanium catalyst will migrate to the acidic sites of the molecular sieve under operating conditions, thereby protecting the active sites of the vanadium-titanium catalyst from being occupied. If the molecular sieve does not contain such exchangeable hydrogen ions and / or ammonium ions, the active sites in the vanadium-titanium catalyst will be more easily occupied, resulting in a significant weakening of the effect of the molecular sieve on the catalyst's resistance to alkali poisoning. In addition, it should be noted that the molecular sieve should be doped with other metals as much as possible, because the doped metals will occupy part of the acidic sites in the molecular sieve, which is not conducive to the improvement of the anti-alkali poisoning performance.

[0011] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0012] Preferably, the molecular sieve includes any one or a combination of at least two of BEA molecular sieve, AEI molecular sieve, Y molecular sieve, MFI molecular sieve, MOR molecular sieve, FER molecular sieve, FAU molecular sieve, CHA molecular sieve or KFI molecular sieve, and more preferably any one or a combination of at least two of BEA molecular sieve, Y molecular sieve or KFI molecular sieve.

[0013] It should be noted that the above-mentioned molecular sieves are all H-type molecular sieves and / or ammonium-type molecular sieves. In the present invention, by using the molecular sieve of the above configuration, due to its specific pore structure, acidic properties or ion exchange ability, it is more conducive to improving the alkali poisoning resistance of the catalyst; taking BEA molecular sieve, Y molecular sieve or KFI molecular sieve as examples, the pore diameters in BEA molecular sieve and Y molecular sieve are larger and the pore channels are rich in intersections. On the one hand, this structure is conducive to the diffusion of reactants and products, enabling the denitration reaction to proceed more efficiently. On the other hand, it can accommodate more alkali metal ions and reduce the direct attack of alkali metal ions on the active sites of the vanadium-titanium catalyst; while KFI molecular sieve uses K salt to adjust the alkalinity of the initial gel during synthesis and has a higher selectivity for K ions. This high-selectivity ion exchange ability gives KFI molecular sieve a unique advantage in anti-K poisoning and can more specifically protect the active sites of the vanadium-titanium catalyst.

[0014] Preferably, the silicon-aluminum ratio of the molecular sieve is (5-30):1, more preferably (5-20):1, such as 5:1, 10:1, 15:1, 20:1, 25:1 or 30:1, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0015] In the present invention, by regulating the silicon-aluminum ratio of the molecular sieve, the number of acidic sites in the molecular sieve can be regulated. By controlling the silicon-aluminum ratio of the molecular sieve within (5-30):1, and further within (5-20):1, it can ensure that there are sufficient acidic sites in the molecular sieve to combine with alkali metals and / or alkaline earth metals, which is more conducive to dealing with the situation where the content of alkali metals and / or alkaline earth metals in the ash is relatively high; while if the silicon-aluminum ratio is too high, the acidic sites in the molecular sieve will decrease, which is not conducive to the improvement of alkali poisoning resistance.

[0016] Preferably, the vanadium-titanium catalyst includes a carrier TiO2 and V2O5 supported on the TiO2.

[0017] Preferably, the structure of the TiO2 includes an anatase structure.

[0018] Preferably, the specific surface area of the TiO2 is 10m 2 / g to 40m 2 / g, such as 10m 2 / g, 15m2 / g, 20 m 2 / g, 25 m 2 / g, 30 m 2 / g, 35 m 2 / g or 40 m 2 / g etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0019] In the present invention, the loading amount of vanadium oxide can be regulated by controlling the specific surface area of TiO₂. When the specific surface area of TiO₂ is within the range of 10 m 2 / g to 40 m 2 / g, it is more conducive to loading vanadium oxide on the TiO₂ support in the form of aggregates, so that the catalyst can have high catalytic activity even at a relatively low vanadium loading, meeting the more stringent requirements for vanadium content in industry.

[0020] Preferably, based on the mass of the vanadium-titanium catalyst being 100 wt%, the mass proportion of V₂O₅ is (0.5 - 3) wt%, such as 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt% or 3 wt% etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0021] In the present invention, by controlling the mass proportion of V₂O₅ within the range of (0.5 - 3) wt%, it is more conducive to taking into account both the denitrification activity of the catalyst and industrial requirements.

[0022] Preferably, the mass ratio of the vanadium-titanium catalyst to the molecular sieve is (1 - 5):1, preferably (1.5 - 3):1, such as 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1 etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0023] In the present invention, by regulating the mass ratio of the vanadium-titanium catalyst to the molecular sieve, the denitrification activity and alkali poisoning resistance of the catalyst can be adjusted; by controlling the mass ratio of the vanadium-titanium catalyst to the molecular sieve within the range of (1 - 5):1 and further within the range of (1.5 - 3):1, it is more conducive to enabling the catalyst to simultaneously possess high denitrification activity and alkali poisoning resistance performance.

[0024] Second, the present invention provides a preparation method of an alkali poisoning resistant denitrification catalyst as described in the first aspect. The preparation method includes: mixing the vanadium-titanium catalyst and the molecular sieve to obtain the alkali poisoning resistant denitrification catalyst; the molecular sieve includes H-type molecular sieve and / or ammonium-type molecular sieve.

[0025] In the present invention, only by mixing a vanadium-titanium catalyst with an H-type molecular sieve and / or an ammonium-type molecular sieve to make them tightly combined together can the alkali poisoning resistance of the vanadium-titanium catalyst be significantly improved. The preparation method is simple and suitable for industrial application.

[0026] Preferably, the mass ratio of the vanadium-titanium catalyst to the molecular sieve is (1 - 5):1, preferably (1.5 - 3):1, such as 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0027] Preferably, the mixing includes ball milling, and more preferably wet ball milling.

[0028] Preferably, during the wet ball milling process, the mass ratio of the total mass of the vanadium-titanium catalyst and the molecular sieve to the mass of the solvent is (5 - 7):1, such as 5:1, 5.5:1, 6:1, 6.5:1 or 7:1, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0029] Preferably, the ball milling time is 0.5 h - 2 h, such as 0.5 h, 1 h, 1.5 h or 2 h, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0030] In the present invention, by adopting wet ball milling, controlling the mass ratio of the total mass of the vanadium-titanium catalyst and the molecular sieve to the solvent within (5 - 7):1, and controlling the ball milling time within the range of 0.5 h - 2 h, it is more conducive to obtaining catalyst powder with uniform mixing and tight combination.

[0031] Preferably, the preparation method of the vanadium-titanium catalyst includes: mixing a vanadium source solution and TiO₂, drying after evaporation, and finally calcining to obtain the vanadium-titanium catalyst.

[0032] Preferably, the vanadium source includes ammonium metavanadate.

[0033] Preferably, the ratio of the mass of TiO₂ to the volume of the vanadium source solution is (0.5 - 2):10, such as 0.5:10, 1:10, 1.5:10 or 2:10, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0034] Preferably, before mixing the vanadium source solution and TiO₂, the TiO₂ is pretreated.

[0035] Preferably, the pretreatment includes calcining the TiO₂.

[0036] Preferably, the temperature of the calcination treatment is 700°C to 800°C, such as 700°C, 720°C, 740°C, 750°C, 760°C, 780°C or 800°C, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0037] Preferably, the time of the calcination treatment is 3h to 8h, such as 3h, 4h, 5h, 6h, 7h or 8h, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0038] In the present invention, by calcining TiO2 at 700°C to 800°C for 3h to 8h, the specific surface area of TiO2 can be significantly reduced, thereby reducing the loading amount of vanadium oxide.

[0039] Preferably, the evaporation includes rotary evaporation.

[0040] Preferably, the temperature of the drying is 90 - 110°C, such as 90°C, 95°C, 100°C, 105°C or 110°C, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0041] Preferably, the temperature of the roasting is 400°C to 600°C, such as 400°C, 450°C, 500°C, 550°C or 600°C, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0042] Preferably, the time of the roasting is 2h to 4h, such as 2h, 2.5h, 3h, 3.5h or 4h, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0043] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0044] First, calcine TiO2 at 700°C to 800°C for 3h to 8h, mix the vanadium source solution with the calcined TiO2, evaporate and then dry, and finally roast to obtain a vanadium-titanium catalyst; then mix the vanadium-titanium catalyst and the molecular sieve in a mass ratio of (1.5 - 3):1, and then add a solvent to the ball-milling device according to a mass ratio of the total mass of the vanadium-titanium catalyst and the molecular sieve to the solvent of (5 - 7):1, and obtain the anti-alkali-poisoning denitration catalyst after ball-milling for 0.5h to 2h;

[0045] The molecular sieve includes an H-type molecular sieve or an ammonium-type molecular sieve.

[0046] In the third aspect, the present invention also provides an application of the anti-alkali-poisoning denitration catalyst as described in the first aspect, and the application includes ammonia selective catalytic reduction denitration.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The catalyst provided by the present invention has excellent ability to resist poisoning by alkali metals and alkaline earth metals, and the preparation method is simple, and it is especially suitable for the case where the alkali metal content in the ash of ammonia selective catalytic reduction denitration is relatively high. Description of the Drawings

[0049] Figure 1 is the NO conversion rate curve of the catalysts provided in Example 1, Comparative Example 1, Verification Example 1 and Comparative Verification Example 1.1 x conversion rate curve.

[0050] Figure 2 is the NO conversion rate curve of the catalysts provided in Comparative Verification Example 1.1 and Comparative Verification Example 1.2 x conversion rate curve. Detailed Embodiments

[0051] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the described embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above description of the drawings are intended to cover non-exclusive inclusion.

[0053] Example 1

[0054] This example provides an anti-alkali poisoning denitration catalyst, which includes a denitration component vanadium-titanium catalyst VTi and an anti-alkali poisoning component ammonium-type zeolite with BEA configuration. VTi includes a carrier TiO2 and a main active substance V2O5 loaded on TiO2; wherein, the loading amount of V2O5 is 1 wt%, the specific surface area of TiO2 is 85 m 2 / g, the silicon-aluminum ratio in the zeolite is 10:1, and the preparation method is as follows:

[0055] (1) Prepare the vanadium-titanium catalyst: Mix TiO2 and ammonium metavanadate solution in a ratio of 1:10 (g / mL), continuously stir at room temperature for 2 h, after rotary evaporation, put the obtained catalyst into an oven and dry it overnight at 100 °C, and finally calcine it in a muffle furnace at 500 °C in an air atmosphere for 3 h to obtain the vanadium-titanium catalyst VTi;

[0056] (2) Preparation of alkali-poisoning-resistant denitration catalyst: Add VTi and ammonium-type zeolite with BEA configuration into a ball mill at a ratio of 7:3, and add water at a mass ratio of 5:1 based on the total mass of VTi and zeolite. Ball mill for 1 h at room temperature to obtain the alkali-poisoning-resistant denitration catalyst VTi+BEA.

[0057] Example 2

[0058] This example provides an alkali-poisoning-resistant denitration catalyst, which includes a denitration component vanadium-titanium catalyst VTi and an alkali-poisoning-resistant component H-type zeolite with Y configuration. VTi includes a carrier TiO2 and a main active substance V2O5 supported on TiO2. Among them, the loading amount of V2O5 is 3 wt%, the specific surface area of TiO2 is 85 m 2 / g, the silica-alumina ratio in the zeolite is 20:1, and the preparation method is as follows:

[0059] (1) Preparation of vanadium-titanium catalyst: Mix TiO2 and ammonium metavanadate solution at a ratio of 1:10 (g / mL), continuously stir at room temperature for 2 h, after rotary evaporation, put the obtained catalyst into an oven and dry it overnight at 100 °C, and finally calcine it in a muffle furnace at 500 °C in an air atmosphere for 3 h to obtain the vanadium-titanium catalyst VTi;

[0060] (2) Preparation of alkali-poisoning-resistant denitration catalyst: Add VTi and H-type zeolite with Y configuration into a ball mill at a ratio of 3:1, and add water at a mass ratio of 6:1 based on the total mass of VTi and zeolite. Ball mill for 1.5 h at room temperature to obtain the alkali-poisoning-resistant denitration catalyst VTi+Y.

[0061] Example 3

[0062] This example provides an alkali-poisoning-resistant denitration catalyst, which includes a denitration component vanadium-titanium catalyst VTi and an alkali-poisoning-resistant component ammonium-type zeolite with KFI configuration. VTi includes a carrier TiO2 and a main active substance V2O5 supported on TiO2. Among them, the loading amount of V2O5 is 2 wt%, the specific surface area of TiO2 is 85 m 2 / g, the silica-alumina ratio in the zeolite is 5:1, and the preparation method is as follows:

[0063] (1) Preparation of vanadium-titanium catalyst: Mix TiO2 and ammonium metavanadate solution at a ratio of 1:10 (g / mL), continuously stir at room temperature for 2 h, after rotary evaporation, put the obtained catalyst into an oven and dry it overnight at 100 °C, and finally calcine it in a muffle furnace at 500 °C in an air atmosphere for 3 h to obtain the vanadium-titanium catalyst VTi;

[0064] (2) Preparation of an anti-alkali-poisoning denitration catalyst: Add VTi and an ammonium-type molecular sieve of the KFI configuration to a ball mill in a ratio of 1.5:1, and add water in a mass ratio of 7:1 based on the total mass of VTi and the molecular sieve. Ball mill at room temperature for 2 h to obtain the anti-alkali-poisoning denitration catalyst VTi + KFI.

[0065] Example 4

[0066] The difference between this example and Example 1 is that in this example, the specific surface area of TiO2 is 15 m 2 / g, and the loading amount of V2O5 is 0.5 wt%; in the preparation method, before step (1), TiO2 is calcined at 750 °C for 5 h;

[0067] The remaining preparation processes and parameters are the same as those in Example 1.

[0068] Example 5

[0069] The difference between this example and Example 1 is that in this example, the silica-alumina ratio in the molecular sieve is 25:1;

[0070] The remaining preparation processes and parameters are the same as those in Example 1.

[0071] Example 6

[0072] The difference between this example and Example 1 is that in this example, the silica-alumina ratio in the molecular sieve is 40:1;

[0073] The remaining preparation processes and parameters are the same as those in Example 1.

[0074] Example 7

[0075] The difference between this example and Example 1 is that in this example, the silica-alumina ratio in the molecular sieve is 3:1;

[0076] The remaining preparation processes and parameters are the same as those in Example 1.

[0077] Example 8

[0078] The difference between this example and Example 1 is that in this example, VTi and an ammonium-type molecular sieve of the BEA configuration are added to a ball mill in a ratio of 4:1;

[0079] The remaining preparation processes and parameters are the same as those in Example 1.

[0080] Example 9

[0081] The difference between this example and Example 1 is that in this example, VTi and an ammonium-type molecular sieve of the BEA configuration are added to a ball mill in a ratio of 6:1;

[0082] The remaining preparation processes and parameters are the same as those in Example 1.

[0083] Example 10

[0084] The difference between this example and Example 1 is that in this example, VTi and the ammonium-type molecular sieve with BEA configuration are added to the ball mill at a ratio of 0.5:1;

[0085] The remaining preparation processes and parameters are the same as those in Example 1.

[0086] Example 11

[0087] The difference between this example and Example 1 is that in this example, the molecular sieve is the ammonium-type molecular sieve with MFI configuration;

[0088] The remaining preparation processes and parameters are the same as those in Example 1.

[0089] Example 12

[0090] The difference between this example and Example 1 is that in this example, in step (2) of the preparation process, water is added at a mass ratio of 3:1 based on the total mass of VTi and the molecular sieve;

[0091] The remaining preparation processes and parameters are the same as those in Example 1.

[0092] Comparative Example 1

[0093] The difference between this comparative example and Example 1 is that in this comparative example, the alkali-poisoning resistant denitration catalyst only includes the denitration component vanadium-titanium catalyst VTi and does not contain a molecular sieve;

[0094] The remaining preparation processes and parameters are the same as those in Example 1.

[0095] Comparative Example 2

[0096] The difference between this comparative example and Example 1 is that in this comparative example, the molecular sieve is the Na-type molecular sieve with BEA configuration;

[0097] The remaining preparation processes and parameters are the same as those in Example 1.

[0098] To prove that the alkali-poisoning resistant denitration catalyst prepared by the present invention still has high denitration activity after experiencing alkali poisoning, and that its catalytic activity can be restored by mixing the poisoned catalyst and the molecular sieve, the following verification experiments were carried out:

[0099] Verification Example 1

[0100] Preparation of K-poisoned VTi+BEA: According to the K loading of 2 wt%, the VTi+BEA catalyst powder prepared in Example 1 was impregnated in KNO3 solution for 12 h, then dried in an oven at 100 °C, and then calcined in a muffle furnace at 500 °C for 3 h in an air atmosphere to obtain a powdered poisoned catalyst, denoted as K-VTi+BEA.

[0101] Verification Example 2

[0102] The difference between this verification example and Verification Example 1 is that the KNO3 solution was replaced with a NaNO3 solution, and the poisoned catalyst was Na-VTi+BEA;

[0103] The remaining preparation methods and parameters were the same as those in Verification Example 1.

[0104] Verification Example 3

[0105] The difference between this verification example and Verification Example 1 is that according to the Ca loading of 4 wt%, the KNO3 solution was replaced with a Ca(NO3)2 solution, and the poisoned catalyst was Ca-VTi+BEA;

[0106] The remaining preparation methods and parameters were the same as those in Verification Example 1.

[0107] Verification Examples 4-14

[0108] The difference between Verification Examples 4-14 and Verification Example 1 is that the catalyst powder prepared in Example 1 was replaced with the catalyst powders prepared in Examples 2-12;

[0109] The remaining preparation methods and parameters were the same as those in Verification Example 1.

[0110] Comparative Verification Example 1.1

[0111] Preparation of K-poisoned VTi: According to the K loading of 2 wt%, the VTi catalyst powder prepared in Comparative Example 1 was impregnated in KNO3 solution for 12 h, then dried in an oven at 100 °C, and then calcined in a muffle furnace at 500 °C for 3 h in an air atmosphere to obtain a powdered poisoned catalyst, denoted as K-VTi.

[0112] Comparative Verification Example 1.2

[0113] The poisoned catalyst K-VTi prepared in Verification Example 1 was mixed with an ammonium-type molecular sieve of BEA configuration in a ratio of 1:1, added to a ball mill and milled for 1 h. The mixed catalyst powder was pressed and sieved, and 40-60 mesh was taken. It was hydrothermally treated at 500 °C for 24 h in an atmosphere with a volume fraction of 10% H2O, 20% O2, and the rest balanced with N2.

[0114] Comparative Verification Example 2

[0115] The difference between this comparative verification example and Comparative Verification Example 1 is that the KNO3 solution is replaced with a NaNO3 solution, and the poisoned catalyst is Na-VTi+BEA;

[0116] The remaining preparation methods and parameters are the same as those in Comparative Verification Example 1.

[0117] Comparative Verification Example 3

[0118] The difference between this comparative verification example and Comparative Verification Example 1 is that according to a Ca loading of 4 wt%, the KNO3 solution is replaced with a Ca(NO3)2 solution, and the poisoned catalyst is Ca-VTi+BEA;

[0119] The remaining preparation methods and parameters are the same as those in Comparative Verification Example 1.

[0120] Comparative Verification Example 4

[0121] The difference between Comparative Verification Example 4 and Comparative Verification Example 1 is that the catalyst powder prepared in Comparative Example 1 is replaced with the catalyst powder prepared in Comparative Example 2;

[0122] The remaining preparation methods and parameters are the same as those in Comparative Verification Example 1.

[0123] Performance Test

[0124] The catalyst powders prepared in Example 1, Comparative Example 1, Verification Examples 1-14, and Comparative Verification Examples 1-4 were pressed into tablets and sieved. 40-60 mesh was taken and the activity was tested at different temperatures with the same mass; among them, the test space velocity was 80,000 h -1 , the composition of the test gas was 500 ppm of NO, 500 ppm of NH3, 5% of O2, 5% of H2O, and the balance gas was N2. The components in the tail gas were detected by a Fourier transform infrared spectrometer, and the conversion efficiency of NO x was calculated. The curve of the NO x conversion efficiency varying with the reaction temperature is as shown Figure 1-2 in the figure, and the relevant data are shown in Tables 1 and 2.

[0125] Table 1

[0126]

[0127] Table 2

[0128]

[0129]

[0130] From Figure 1As can be seen from Table 1, by combining molecular sieve with vanadium-titanium catalyst, the alkali-poisoning resistance of the catalyst is significantly improved. Taking 300 °C as an example, when the alkali metal poisoning dose is 2% or 4%, for NO x it still has a conversion rate of more than 85%, and the conversion rate decreases by less than 5% compared with that before poisoning. While for the catalyst without molecular sieve, when the alkali metal poisoning dose is 2% or 4%, the conversion rate of NO x is less than 5%, showing a significant decrease compared with the conversion rate before poisoning; moreover, through Figure 2 and the data comparison of Comparative Verification Examples 1.1 and 1.2 in Table 1, it can be seen that by combining the poisoned catalyst VTi with ammonium-type molecular sieve, the catalytic activity of VTi can be restored to a large extent. This also shows that the addition of molecular sieve provides a large number of sites for accommodating alkali metal and / or alkaline earth metal ions, enabling the alkali metal and / or alkaline earth metal ions deposited on the vanadium-titanium catalyst to migrate to the acidic sites of the molecular sieve under operating conditions, thus protecting the active sites of the vanadium-titanium catalyst from being occupied.

[0131] From the comparison between Verification Example 1 and Verification Example 6 in Table 2, it can be seen that pretreating TiO2 can reduce the vanadium oxide loading amount without reducing its conversion rate for NO x ; from Verification Examples 7 - 14, it can be known that the silica-alumina ratio in the molecular sieve, the mass ratio of vanadium-titanium catalyst to molecular sieve, the type of molecular sieve, and the addition amount of solvent in wet ball milling will all affect the activity of the catalyst in practical applications. By controlling the parameters of the above factors within the preferred range of the present invention, the conversion rate of the catalyst for NO x can be further improved.

[0132] The applicant declares that the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A denitration catalyst resistant to alkali poisoning, characterized in that: The alkali-poisoning-resistant denitration catalyst comprises a denitration component and an alkali-poisoning-resistant component, wherein the denitration component comprises a vanadium-titanium catalyst, and the alkali-poisoning-resistant component comprises a molecular sieve, wherein the molecular sieve comprises an H-type molecular sieve and / or an ammonium-type molecular sieve.

2. The alkali-poisoning-resistant denitration catalyst according to claim 1, characterized in that: The molecular sieve includes any one of BEA molecular sieve, AEI molecular sieve, Y molecular sieve, MFI molecular sieve, MOR molecular sieve, FER molecular sieve, FAU molecular sieve, CHA molecular sieve or KFI molecular sieve, or a combination of at least two of them, preferably any one of BEA molecular sieve, Y molecular sieve or KFI molecular sieve, or a combination of at least two of them.

3. The alkali-poisoning-resistant denitration catalyst according to claim 1 or 2, characterized in that: The silicon-aluminum ratio of the molecular sieve is (5-30):1, preferably (5-20):

1.

4. The alkali-poisoning-resistant denitration catalyst according to any one of claims 1 to 3, characterized in that: The vanadium-titanium catalyst comprises a carrier TiO2 and V2O5 supported on the TiO2; Preferably, the structure of the TiO2 comprises an anatase structure; Preferably, the specific surface area of ​​the TiO2 is 10m 2 / g~40m 2 / g; Preferably, based on the mass of the vanadium-titanium catalyst being 100 wt%, the mass of the V2O5 accounts for (0.5-3) wt%.

5. The alkali-poisoning-resistant denitration catalyst according to any one of claims 1 to 4, characterized in that: The mass ratio of the vanadium-titanium catalyst to the molecular sieve is (1-5):1, preferably (1.5-3):

1.

6. A method for preparing an alkali-poisoning-resistant denitration catalyst according to any one of claims 1 to 5, characterized in that: The preparation method comprises: mixing a vanadium-titanium catalyst and a molecular sieve to obtain the alkali-poisoning-resistant denitration catalyst; the molecular sieve comprises an H-type molecular sieve and / or an ammonium-type molecular sieve.

7. The method for preparing the alkali-poisoning resistant denitration catalyst according to claim 6, characterized in that: The mass ratio of the vanadium-titanium catalyst to the molecular sieve is (1-5):1, preferably (1.5-3):1; Preferably, the mixing comprises ball milling, more preferably wet ball milling; Preferably, during the wet ball milling process, the mass ratio of the total mass of the vanadium titanium catalyst and the molecular sieve to the mass of the solvent is (5-7):1; Preferably, the ball milling time is 0.5 h to 2 h.

8. The method for preparing the alkali-poisoning resistant denitration catalyst according to claim 6 or 7, characterized in that: The preparation method of the vanadium-titanium catalyst comprises: mixing a vanadium source solution and TiO2, drying after evaporation, and finally calcining to obtain the vanadium-titanium catalyst; Preferably, before the vanadium source solution and TiO2 are mixed, the TiO2 is pretreated; Preferably, the pretreatment comprises calcining TiO2; Preferably, the calcination temperature is 700°C to 800°C; Preferably, the calcination treatment time is 3h to 8h.

9. The method for preparing the alkali-poisoning resistant denitration catalyst according to claim 6, characterized in that: The preparation method comprises the following steps: firstly, calcining TiO2 at 700-800°C for 3-8h, mixing a vanadium source solution and the calcined TiO2, drying after evaporation, and finally calcining to obtain a vanadium-titanium catalyst; then, mixing the vanadium-titanium catalyst and a molecular sieve in a mass ratio of (1.5-3):1, and then adding a solvent to a ball mill in a mass ratio of the total mass of the vanadium-titanium catalyst and the molecular sieve to the solvent in a mass ratio of (5-7):1, and ball milling for 0.5-2h to obtain the alkali-poisoning-resistant denitration catalyst; The molecular sieve includes an H-type molecular sieve or an ammonium-type molecular sieve.

10. An application of the alkali-poisoning resistant denitration catalyst according to any one of claims 1 to 5, characterized in that: The applications include ammonia selective reduction denitrification.

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