Preparation method and application of a rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning

Abstract

The present invention belongs to the technical field of NH3-SCR catalysis, and relates to a preparation method and application of a rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning. In the present invention, a mixture of a silicon source, an aluminum source, an alkali source, a template agent, water, a rare earth source and a chelating agent is used as a first reaction system. After hydrothermal reaction, it is filtered, dried and calcined to obtain a first reaction product; the first reaction product is mixed with an ammonium source and used as a second reaction system, and a second reaction product is obtained through a first microwave ultrasonic reaction; the second reaction product is mixed with a copper source and used as a third reaction system, and a third reaction product is obtained through a second microwave ultrasonic reaction; the third reaction product is subjected to a calcination treatment to obtain the rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning. It has excellent alkali metal poisoning resistance and catalytic activity.

Description

Technical Field

[0001] The present invention relates to the field of NH 3 -SCR catalytic technology, and particularly to a preparation method and application of a rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning. Background Art

[0002] NH 3 Selective catalytic reduction of nitrogen oxides (NH 3 -SCR) is currently widely used in the elimination of nitrogen oxides in the diesel vehicle exhaust aftertreatment system.

[0003] In the prior art, Cu-SSZ-13 molecular sieve has excellent NH 3 -SCR catalytic performance and hydrothermal aging performance and is widely used in the purification of diesel vehicle exhaust NO x However, in the diesel vehicle exhaust aftertreatment NH 3 -SCR system, since the urea solution and the biodiesel additive in the engine lubricating oil contain alkali metals, these alkali metal oxides will react with the Cu-SSZ-13 molecular sieve catalyst, reducing the acid amount and the amount of active sites of the Cu-SSZ-13 molecular sieve, resulting in a decrease in catalytic activity.

[0004] Therefore, developing a denitration catalyst with excellent alkali metal resistance is of great significance for improving denitration efficiency and stability and reducing the frequent replacement of catalysts. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method and application of a rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning to solve the problems existing in the above prior art.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention: providing a preparation method of a rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning, the steps include:

[0008] Using a mixture of a silicon source, an aluminum source, an alkali source, a template agent, water, a rare earth source, and a chelating agent as a first reaction system, after hydrothermal reaction, through filtration, drying, and calcination, a first reaction product is obtained;

[0009] Mixing the first reaction product with an ammonium source and using it as a second reaction system, and obtaining a second reaction product through a first microwave ultrasonic reaction;

[0010] Mixing the second reaction product with a copper source and using it as a third reaction system, and obtaining a third reaction product through a second microwave ultrasonic reaction;

[0011] Performing a calcination treatment on the third reaction product gives the rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning.

[0012] Further, the molar ratio of the silicon source, aluminum source, alkali source, template agent, water, and rare earth source is 20-30:1:2-5:1-5:200-1000:0.05-2, preferably 20-30:1:2.5-4:1.1-4:200-1000:0.05-1.5; wherein, the silicon source is calculated as silicon dioxide, the aluminum source is calculated as aluminum oxide, the alkali source is calculated as OH - calculated, and the rare earth source is calculated as rare earth element.

[0013] Under the condition of the limited molar ratio of the rare earth source and the aluminum source, it is beneficial to improve the anti-K catalytic activity of the molecular sieve; under the condition of the limited molar ratio of the alkali source, template agent and aluminum source, the catalytic activity of the molecular sieve can be effectively improved.

[0014] Further, the molar ratio of the rare earth source to the chelating agent is 1:2-10, preferably 1:3-8.

[0015] Further, the chelating agent includes at least one of trisodium ethylenediamine-N,N-disuccinate, calcium trisodium diethylenetriaminepentaacetate, sodium diethyl oxalacetate, disodium ethylenediaminetetraacetate, pentasodium diethylenetriaminepentaacetate, tetrasodium ethylenediaminetetraacetate, trisodium nitrilotriacetate, calcium disodium ethylenediaminetetraacetate, trisodium N-hydroxyethyl ethylenediaminetriacetate, trisodium ethylenediaminetetraacetate, trisodium triphenylphosphine metasulfonate, magnesium disodium ethylenediaminetetraacetate, disodium N-methyliminodiacetate, sodium 1,3-benzoxazol-2-ylacetate, trisodium 6-phosphogluconate, and trisodium N-(2-hydroxyethyl)ethylenediamine-N,N and N-triacetate.

[0016] Further, the rare earth source includes at least one of rare earth nitrates, rare earth acetates, rare earth chlorides, and rare earth oxides, preferably rare earth nitrates or rare earth acetates. Among them, the rare earth elements include at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium, ytterbium, and yttrium. Preferably at least one of lanthanum, cerium, europium, ytterbium, and yttrium.

[0017] Further, the aluminum source includes at least one of pseudo-boehmite, aluminum hydroxide, aluminum sol, and sodium aluminate, preferably sodium aluminate and / or aluminum sol, more preferably sodium aluminate.

[0018] The solid content of the aluminum sol is 8-20 wt%, the pH is 3-6, the viscosity is 35-50 Pa·s, and the particle size is 5-15 nm.

[0019] Further, the silicon source includes at least one of silicate esters, silicon oxide, fumed silica, silica sol, and colloidal silica, preferably silica sol and / or fumed silica, and more preferably silica sol.

[0020] Preferably, the silica sol has a solid content of 15 - 30 wt%, a pH value of 3 - 10, a density of 1 - 2 g / cm 3 , and a particle size of 8 - 15 nm.

[0021] Further, the base source includes inorganic bases or organic bases.

[0022] Preferably, the inorganic base includes sodium hydroxide and / or potassium hydroxide.

[0023] Preferably, the organic base includes at least one of sodium alkoxide, potassium alkoxide, and tetraethylammonium hydroxide, and more preferably sodium alkoxide and / or potassium alkoxide.

[0024] Further, the template agent includes at least one of N,N,N-trimethyladamantylammonium, benzyltrimethylammonium, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide, and preferably N,N,N-trimethyladamantylammonium.

[0025] Further, the ammonium source includes ammonium nitrate and / or ammonium chloride.

[0026] Further, the molar ratio of the ammonium source to the aluminum source is 2.1 - 8:1, preferably 4 - 8:1, and more preferably 4 - 7:1, where the ammonium source is calculated as NH 4 + counted.

[0027] Further, the copper source includes at least one of copper nitrate, copper sulfate, copper chloride, copper gluconate, copper propionate, copper acetate, copper isopropionate, and copper glutamate chelate, preferably copper glutamate chelate and / or copper acetate, and particularly preferably copper acetate.

[0028] It should be noted that the copper source here is an aqueous solution, and the concentration of copper ions is 0.1 - 0.4 mol / L.

[0029] Further, the mass ratio of the sum of the masses of the aluminum source and the silicon source to the mass of the copper source is 1:0.5 - 8, preferably 1:1 - 4.

[0030] Further, the temperature of the hydrothermal reaction is 120 - 200 °C, and the time is 2 - 5 days.

[0031] Preferably, the temperature of the hydrothermal reaction is 140 - 180 °C, and the time is 3 - 4 days.

[0032] Further, the temperature of the first microwave ultrasonic reaction is 40 - 90 °C, and the time is 1 - 24 h.

[0033] Preferably, the temperature of the first microwave ultrasonic reaction is 70-90°C, and the time is 2-12 h.

[0034] Furthermore, the temperature of the second microwave ultrasonic reaction is 40-90°C, and the time is 1-24 h.

[0035] Preferably, the temperature of the second microwave ultrasonic reaction is 70-90°C, and the time is 2-12 h.

[0036] Furthermore, the microwave power of the first microwave ultrasonic reaction and the second microwave ultrasonic reaction is 0-1500 W, and the ultrasonic power is 0-1000 W, and it is not 0.

[0037] Preferably, the microwave power of the first microwave ultrasonic reaction and the second microwave ultrasonic reaction is 700-1000 W, and the ultrasonic power is 500-900 W.

[0038] Furthermore, the temperature of the drying is 60-110°C, and the time is 3-24 h.

[0039] Furthermore, the temperature of the calcination is 450-800°C, and the time is 1-5 h; the calcination temperature can be 500°C, 550°C, 600°C, 700°C or 800°C, and the calcination time can be 1 h, 2 h, 3 h, 4 h or 5 h.

[0040] Preferably, the temperature of the calcination is 500-600°C, and the time is 2-4 h.

[0041] Furthermore, the temperature of the calcination treatment is 450-800°C, and the time is 1-5 h; the temperature of the calcination treatment can be 500°C, 550°C, 600°C, 700°C or 800°C, and the time of the calcination treatment can be 1 h, 2 h, 3 h, 4 h or 5 h.

[0042] Preferably, the temperature of the calcination treatment is 500-600°C, and the time is 2-4 h.

[0043] The second technical solution of the present invention: Provide a rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning prepared by the above preparation method.

[0044] Furthermore, the mass fraction of rare earth elements in the rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning is 250 ppm-1 wt% (rare earth elements are counted as rare earth simple substances), and the content of copper elements is 2-4 wt% (copper elements are counted as Cu).

[0045] Furthermore, the alkali metal poisoning-resistant rare earth-based copper molecular sieve is a CHA-type Cu-SSZ-13 molecular sieve. The active components in the molecular sieve are rare earth elements and copper elements, and silicon elements and aluminum elements are the molecular sieve framework.

[0046] The third technical solution of the present invention: Provide an application of the above-mentioned rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning in NH 3 -SCR in an environment containing alkali metal oxides.

[0047] The present invention discloses the following technical effects:

[0048] The rare earth-based copper molecular sieve denitration catalyst prepared by the present invention can firmly embed rare earth ions into the rings in the molecular sieve during the synthesis of the molecular sieve framework. Subsequent microwave ultrasonic treatment can also embed active copper into the rings in the molecular sieve, thereby enhancing the interaction between rare earth and the molecular sieve.

[0049] The catalyst in the present invention has good alkali metal poisoning resistance. Through the synergistic effect of rare earth ions and active copper, the formation of inactive CuO x is inhibited, thereby improving its alkali metal poisoning resistance. Description of the Drawings

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0051] Figure 1 EPR diagrams of the catalysts prepared in Example 2 and Comparative Example 1 before and after poisoning;

[0052] Figure 2 XPS diagrams of the catalysts prepared in Example 2 and Comparative Example 2 after poisoning. Detailed Embodiments

[0053] Now, the various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0054] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0055] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0056] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the specification of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of this invention are obvious to those skilled in the art. The specification and examples of this invention are merely exemplary.

[0057] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0058] Example 1

[0059] The preparation steps of the rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning are as follows: S1. 0.012 mol of N,N,N-trimethyladamantammonium (template agent), 0.0084 mol of sodium hydroxide (alkali source), 0.0036 mol of potassium hydroxide (alkali source) and 2.23 mol of water are stirred evenly under the condition of heating under reflux at a temperature of 40 °C to form a first mixture. 0.006 mol of aluminum sol (aluminum source) (solid content 10 wt%, pH 4, viscosity 43 mPa·s, particle size 10 nm), 0.88 mmol of yttrium acetate (rare earth source), and 5.28 mmol of pentasodium diethylenetriaminepentaacetate (chelating agent) are added to the first mixture to form a second mixture. 0.12 mol of silica sol (silica source) (solid content 20%, pH 3.5, density 1.5 g / cm 3 ) is mixed with the second mixture and stirred until a homogeneous gel is formed to form a third mixture; the mixture is loaded into a hydrothermal reaction kettle lined with polytetrafluoroethylene, hydrothermally crystallized at 180 °C for 4 days, the crystallized product is washed three times with deionized water, microwave dried overnight at 110 °C, and microwave calcined at 600 °C for 4 h to obtain a first reaction product;

[0060] S2. The first reaction product is added to 25 mL of an aqueous solution of 1.5 mol / L ammonium nitrate, and the reaction is carried out at a microwave power of 1000 W, a constant ultrasonic power of 800 W, and a temperature of 70 °C for 5 h. The product is washed three times with deionized water and microwave dried overnight at 110 °C to obtain a second reaction product (ammonium-exchanged molecular sieve);

[0061] S3. Add the second reaction product (ammonium-exchanged molecular sieve) to 12 g of 0.35 mol / L aqueous solution of copper glutamate chelate. Under the conditions of microwave power of 1000 W, constant ultrasonic power of 800 W, and temperature of 70 °C, react for 4 h. Wash the exchanged product three times with deionized water, dry it overnight by microwave at 110 °C, and calcine it by microwave at 500 °C for 2 h to obtain the rare earth-based copper molecular sieve denitration catalyst.

[0062] Example 2

[0063] S1. The preparation steps of the alkali metal poisoning-resistant rare earth-based copper molecular sieve denitration catalyst are as follows: S1. Stir 0.012 mol of N,N,N-trimethyladamantammonium, 0.010 mol of sodium alkoxide, and 2.45 mol of water evenly under the condition of heating under reflux at a temperature of 30 °C to form a first mixture; add 0.0088 mol of sodium aluminate, 0.5 mmol of cerium acetate, and 3 mmol of trisodium (2-hydroxyethyl)ethylenediamine-N,N,N-triacetate solution to the first mixture to form a second mixture. Mix 0.11 mol of silica sol (solid content: 20%, pH: 3.5, density: 1.5 g / cm 3 ) with the second mixture and stir until a uniform gel is formed to form a third mixture; load the mixture into a hydrothermal reaction kettle lined with polytetrafluoroethylene, hydrothermally crystallize at 160 °C for 4 days, wash the crystallized product three times with deionized water, dry it overnight by microwave at 110 °C, and calcine it by microwave at 600 °C for 4 h to obtain the first reaction product;

[0064] S2. Add the first reaction product to 20 mL of 2 mol / L aqueous solution of ammonium chloride. Under the conditions of microwave power of 800 W, constant ultrasonic power of 600 W, and temperature of 80 °C, react for 4 h. Wash the product three times with deionized water, dry it overnight by microwave at 110 °C to obtain the second reaction product (ammonium-exchanged molecular sieve);

[0065] S3. Add the second reaction product to 10 g of 0.4 mol / L aqueous solution of copper acetate. Under the conditions of microwave power of 800 W, constant ultrasonic power of 600 W, and temperature of 80 °C, react for 2 h. Wash the exchanged product three times with deionized water, dry it overnight by microwave at 110 °C, and calcine it by microwave at 500 °C for 2 h to obtain the rare earth-based copper molecular sieve denitration catalyst.

[0066] Example 3

[0067] S1. 0.011 mol of N,N,N-trimethyladamantammonium, 0.012 mol of sodium hydroxide and 2.68 mol of water were stirred evenly under heating reflux at a temperature of 50 °C to form a first mixture; 0.0073 mol of sodium aluminate, 0.98 mmol of cerium nitrate and 3 mmol of ethylenediamine-N,N-disuccinic acid trisodium salt were added to the first mixture to form a second mixture, and 0.11 mol of silica sol (solid content: 20%, pH: 3.5, density: 1.5 g / cm 3 ) was mixed with the second mixture and stirred until a homogeneous gel was formed to form a third mixture; the mixture was loaded into a hydrothermal reaction kettle lined with polytetrafluoroethylene and hydrothermally crystallized at 140 °C for 3 days. The crystallized product was washed three times with deionized water, microwave dried at 110 °C overnight, and microwave calcined at 600 °C for 3 h;

[0068] S2. The first reaction product was added to 35 mL of an aqueous solution of 1 mol / L ammonium nitrate. Under the conditions of a microwave power of 900 W, a constant ultrasonic power of 500 W, and a temperature of 80 °C, the reaction was carried out for 3 h. The product was washed three times with deionized water and microwave dried at 110 °C overnight to obtain a second reaction product (ammonium-exchanged molecular sieve);

[0069] S3. The second reaction product was added to 30 g of an aqueous solution of 0.2 mol / L copper acetate. Under the conditions of a microwave power of 800 W, a constant ultrasonic power of 600 W, and a temperature of 80 °C, the reaction was carried out for 3 h. The exchanged product was washed three times with deionized water, microwave dried at 110 °C overnight, and microwave calcined at 500 °C for 2 h to obtain a rare earth-based copper molecular sieve denitration catalyst.

[0070] Comparative Example 1

[0071] The preparation steps of the denitration catalyst were as follows:

[0072] S1. 0.012 mol of N,N,N-trimethyladamantammonium, 0.010 mol of sodium alkoxide, and 0.0088 mol of sodium aluminate were added to 2.45 mol of water and 0.11 mol of silica sol (solid content: 20%, pH: 3.5, density: 1.5 g / cm 3 ) and stirred until a homogeneous gel was formed. The mixture was loaded into a hydrothermal reaction kettle lined with polytetrafluoroethylene and hydrothermally crystallized at 160 °C for 4 days. The crystallized product was washed three times with deionized water, dried overnight in air at 110 °C, and calcined in air at 600 °C for 4 h to obtain a first reaction product;

[0073] S2. The first reaction product was added to 20 mL of an aqueous solution of 2 mol / L ammonium chloride and reacted at room temperature for 4 h. The product was washed three times with deionized water and dried overnight at 110 °C to obtain a second reaction product (ammonium-exchanged molecular sieve);

[0074] S3. Add the second reaction product to 10 g of an aqueous solution of copper acetate at 0.4 mol / L, react at room temperature for 2 h, wash the exchanged product three times with deionized water, dry it overnight in air at 110 °C, and calcine it in air at 500 °C for 2 h to obtain a copper-containing molecular sieve.

[0075] Comparative Example 2

[0076] The preparation steps of the denitration catalyst are as follows:

[0077] Dissolve 0.5 mmol of cerium acetate in water, add H-type zeolite B of the CHA type, stir at room temperature for 12 hours, filter, wash the obtained product with deionized water, and then dry it at 110 °C for 24 hours to obtain zeolite B containing rare earth ions; add zeolite B containing rare earth ions to 10 g of 0.4 mol / L copper acetate, stir at room temperature for 12 h, filter, wash the obtained solid product with deionized water, and then dry it at 100 °C for 24 h. Calcinate the dried product in air at 500 °C for 2 h to obtain a rare earth-containing copper-based zeolite.

[0078] Test Example

[0079] Perform NH 3 -SCR activity tests on the catalysts in Examples 1 to 3 and Comparative Examples 1 to 2. The results of the nitrogen oxide conversion rate are shown in Table 1.

[0080] The test conditions are: [NO] = 500 ppm; [NH 3 = 500 ppm; [O 2 = 10%; [C 3 H 6 = 200 ppm; [CO] = 8 vol%; [H 2 O] = 5 vol%; N 2 is used as the balance gas; the total flow rate is 750 mL / min; the space velocity = 100000 h -1 .

[0081] Table 1

[0082]

[0083] Prepare the catalysts in Examples 1 to 3 and Comparative Examples 1 to 2 into alkali-poisoned catalysts, and perform NH 3 -SCR activity tests. The results of the nitrogen oxide conversion rate are shown in Table 2. The alkali poisoning method is as follows:

[0084] Take 5 g of the catalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 2, dissolve 0.39 g of KNO 3 in deionized water, and use the equal-volume impregnation method. Then add KNO 3The aqueous solution was dropped onto the above molecular sieve, impregnated at room temperature for 6 h, dried overnight by microwave at 110 °C, and calcined by microwave at 500 °C for 2 h to obtain K + a catalyst with a K loading of 3% K / gcat.

[0085] The test conditions were: [NO] = 500 ppm; [NH 3 = 500 ppm; [CO 2 = 8%; [C 3 H 6 = 200 ppm; [O 2 = 10%; [H 2 O] = 5 vol%; N 2 was used as the balance gas; the total flow rate was 750 mL / min; the space velocity = 100000 h -1 .

[0086] Table 2

[0087]

[0088] Figure 1 are the EPR diagrams of the catalysts prepared in Example 2 and Comparative Example 1 before and after poisoning, where the fresh one is before poisoning.

[0089] Figure 2 are the XPS diagrams of the catalysts prepared in Example 2 and Comparative Example 2 after poisoning, where the fresh one is before poisoning.

[0090] From Tables 1-2 and Figures 1-2 the content, it can be seen that:

[0091] In Table 1, before alkali poisoning, the addition timing of rare earth elements does not affect its SCR performance. However, in the SCR catalytic activity data after 3% K poisoning (Table 2), by comparing Examples 1-3 with Comparative Example 1, it can be seen that the NOx conversion rates of Comparative Example 1 at 250 °C, 300 °C, 350 °C, and 400 °C are much lower than those of Examples 1-3 (Table 2). This shows that after alkali metal K poisoning, adding rare earth during the synthesis of molecular sieve has excellent anti-K poisoning performance.

[0092] By comparing Examples 1-3 with Comparative Example 2, it can be seen that the NOx conversion rates of Comparative Example 2 at 250 °C, 300 °C, 350 °C, and 400 °C are much lower than those of Examples 1-3 (Table 2). This shows that after alkali metal K poisoning, the anti-K poisoning performance of rare earth-based copper molecular sieve synthesized by adding rare earth during the synthesis of molecular sieve is better than that of adding rare earth on the basis of molecular sieve.

[0093] By comparing Comparative Example 1 and Comparative Example 2, it can be seen that the NOx conversion rate of Comparative Example 1 at 250 °C, 300 °C, 350 °C and 400 °C is much higher than that of Comparative Example 2. The reason is that rare earth is added on the basis of the molecular sieve. The rare earth is not easy to have a strong interaction with active copper, and at the same time, a part of the active copper sites are covered by the formed rare earth oxides, resulting in a decrease in the anti-K activity.

[0094] The reason is that: adding rare earth ions during the synthesis of the molecular sieve can cause strong interaction between the rare earth ions and active Cu 2+ and inhibit the formation of inactive CuO x , thereby improving its performance of anti-alkali metal poisoning. It can be seen from its XPS ( Figure 2 ) that after adding rare earth Ce on the basis of the molecular sieve, the Ce mainly exists in the form of CeO 2 on the catalyst surface, and thus has a weak interaction with the active copper in the ring, resulting in poor anti-K poisoning performance.

[0095] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning, characterized in that the steps include: A first reaction product is obtained by using a mixture of a silicon source, an aluminum source, an alkali source, a template agent, water, a rare earth source and a chelating agent as a first reaction system, performing a hydrothermal reaction, filtering, drying and roasting; The first reaction product is mixed with an ammonium source to form a second reaction system, and subjected to a first microwave ultrasonic reaction to obtain a second reaction product; The second reaction product is mixed with a copper source to form a third reaction system, and subjected to a second microwave ultrasonic reaction to obtain a third reaction product; The third reaction product is subjected to calcination treatment to obtain the rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning; The molar ratio of the silicon source, aluminum source, alkali source, template, water and rare earth source is 20-30:1:2-5:1-5:200-1000:0.05-2; the molar ratio of the rare earth source to the chelating agent is 1:2-10; the molar ratio of the ammonium source to the aluminum source is 2.1-8:1; the mass ratio of the sum of the mass of the aluminum source and the silicon source to the mass of the copper source is 1:0.5-8; The chelating agent includes at least one of ethylenediamine-N,N'-disuccinic acid trisodium salt, diethylenetriamine pentaacetic acid calcium trisodium salt, diethyl oxalate sodium salt, ethylenediaminetetraacetic acid disodium salt, diethylenetriamine pentaacetic acid pentasodium salt, ethylenediaminetetraacetic acid tetrasodium salt, nitrilotriacetic acid sodium salt, ethylenediaminetetraacetic acid calcium disodium salt, N-hydroxyethylethylenediaminetriacetic acid trisodium salt, ethylenediaminetetraacetic acid trisodium salt, triphenylphosphine tris-sulfonic acid sodium salt, ethylenediaminetetraacetic acid disodium magnesium salt, N-methyliminodiacetic acid disodium salt, 1,3-benzoxazol-2-yl acetate sodium salt, 6-phosphogluconate trisodium salt and N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid trisodium salt; The rare earth source includes at least one of rare earth nitrate, rare earth acetate, rare earth chloride and rare earth oxide; The aluminum source includes at least one of pseudo-boehmite, aluminum hydroxide, aluminum sol and sodium metaaluminate; The silicon source includes at least one of silicate, fumed silica, silica sol and colloidal silica; The alkali source includes an inorganic base or an organic base; The template agent includes at least one of N,N,N-trimethyladamantanammonium, benzyltrimethylammonium, tetraethylammonium hydroxide and tetrapropylammonium hydroxide; The ammonium source includes ammonium nitrate and / or ammonium chloride; The copper source comprises at least one of copper nitrate, copper sulfate, copper chloride, copper gluconate, copper propionate, copper acetate, copper isopropionate and copper glutamate chelate; The inorganic base includes sodium hydroxide and / or potassium hydroxide; the organic base includes sodium alkoxide and / or potassium alkoxide; The rare earth-based copper molecular sieve resistant to alkali metal poisoning is a CHA type Cu-SSZ-13 molecular sieve.

2. The preparation method according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 120-200° C. and the time is 2-5 days.

3. The preparation method according to claim 1, characterized in that: The temperature of the first microwave ultrasonic reaction is 40~90°C, and the time is 1~24 h; the temperature of the second microwave ultrasonic reaction is 40~90°C, and the time is 1~24 h; the microwave power of the first microwave ultrasonic reaction and the second microwave ultrasonic reaction is 0~1500W, and the ultrasonic power is 0~1000W, and is not 0.

4. The preparation method according to claim 1, characterized in that: The drying temperature is 60-110° C., and the time is 3-24 hours; the calcination temperature is 450-800° C., and the time is 1-5 hours.

5. The preparation method according to claim 1, characterized in that: The calcination treatment is carried out at a temperature of 450-800° C. and for a time of 1-5 hours.

6. A rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning as claimed in claim 6 for NH3-SCR in an environment containing alkali metal oxides.

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