Preparation method and application of rare earth-based copper molecular sieve denitration catalyst capable of resisting alkali metal poisoning

Abstract

The 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 capable of resisting alkali metal poisoning. The preparation method comprises the following steps: by taking 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, carrying out hydrothermal reaction, filtering, drying and roasting to obtain a first reaction product; mixing the first reaction product with an ammonium source to obtain a second reaction system, and performing a first microwave ultrasonic reaction to obtain a second reaction product; mixing the second reaction product with a copper source to obtain a third reaction system, and performing a second microwave ultrasonic reaction to obtain a third reaction product; and roasting the third reaction product to obtain the rare earth-based copper molecular sieve denitration catalyst capable of resisting alkali metal poisoning. The catalyst has excellent alkali metal poisoning resistance and catalytic activity.

Description

Technical Field

[0001] The invention relates to the technical field of NH3-SCR catalysis, and in particular to a preparation method and application of a rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning. Background Art

[0002] NH3 selective catalytic reduction of nitrogen oxides (NH3-SCR) is currently widely used to eliminate nitrogen oxides in diesel vehicle exhaust aftertreatment systems.

[0003] In the prior art, Cu-SSZ-13 molecular sieve has excellent NH3-SCR catalytic performance and hydrothermal aging performance and is widely used in diesel vehicle exhaust NO x However, in the diesel exhaust aftertreatment NH3-SCR system, since the urea solution and the biodiesel additives 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 active site amount of the Cu-SSZ-13 molecular sieve, resulting in a decrease in catalytic activity.

[0004] Therefore, developing a denitrification catalyst with excellent resistance to alkali metals is of great significance for improving denitrification 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, so as to solve the problems existing in the above-mentioned prior art.

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

[0007] One of the technical solutions of the present invention is to provide a method for preparing a rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning, the steps comprising:

[0008] 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;

[0009] 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;

[0010] 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;

[0011] 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.

[0012] Furthermore, 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, 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, and the alkali source is calculated as OH. - Rare earth sources are calculated based on rare earth elements.

[0013] Rare earth source and aluminum source under limited molar ratio conditions are beneficial to improving the anti-K catalytic activity of molecular sieve; alkali source, template agent and aluminum source under limited molar ratio conditions can effectively improve the catalytic activity of molecular sieve.

[0014] Furthermore, 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 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 trisulfonic 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 and N-triacetic acid trisodium salt.

[0016] Further, the rare earth source includes at least one of rare earth nitrate, rare earth acetate, rare earth chloride and rare earth oxide, preferably rare earth nitrate or rare earth acetate. The rare earth element includes at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium, ytterbium and yttrium. Preferably, it is at least one of lanthanum, cerium, europium, ytterbium and yttrium.

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

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

[0019] Furthermore, the silicon source includes at least one of silicate, 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, and a density of 1-2 g / cm 3 , particle size is 8 to 15 nm.

[0021] Furthermore, the alkali source includes an inorganic base or an organic base.

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

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

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

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

[0026] Furthermore, the molar ratio of the ammonium source to the aluminum source is 2.1 to 8:1, preferably 4 to 8:1, and more preferably 4 to 7:1, wherein the ammonium source is NH4 + count.

[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, particularly preferably copper acetate.

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

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

[0030] Furthermore, 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] Furthermore, the temperature of the first microwave ultrasonic reaction is 40 to 90° C., and the time is 1 to 24 hours.

[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 to 90° C., and the time is 1 to 24 hours.

[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 to 1500 W, and the ultrasonic power is 0 to 1000 W, and is not 0.

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

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

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

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

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

[0042] Preferably, the calcination treatment is carried out at a temperature of 500 to 600° C. and for a time of 2 to 4 hours.

[0043] The second technical solution of the present invention is to provide a rare earth-based copper molecular sieve denitrification 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 250ppm-1wt% (the rare earth elements are calculated as rare earth elements), and the content of copper elements is 2-4wt% (the copper elements are calculated as Cu).

[0045] Furthermore, the rare earth-based copper molecular sieve resistant to alkali metal poisoning is a CHA type Cu-SSZ-13 molecular sieve, the active components of 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 is to provide an application of the above-mentioned rare earth-based copper molecular sieve denitrification catalyst resistant to alkali metal poisoning for NH3-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 enable rare earth ions to be firmly embedded in the rings in the molecular sieve during the synthesis of the molecular sieve framework, and subsequent microwave ultrasonic treatment can also embed active copper into the rings in the molecular sieve, thereby enhancing the interaction between the rare earth and the molecular sieve.

[0049] The catalyst of the present invention has good resistance to alkali metal poisoning. Through the synergistic effect of rare earth ions and active copper, the inactive CuO x The formation of alkali metal poisoning resistance is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0052] Figure 2 The XPS graphs of the catalysts prepared in Example 2 and Comparative Example 2 after being poisoned. DETAILED DESCRIPTION

[0053] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0054] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0055] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0056] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0057] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0058] Example 1

[0059] The preparation steps of the rare earth-based copper molecular sieve denitrification catalyst resistant to alkali metal poisoning are as follows: S1, 0.012 mol of N,N,N-trimethylammonium adamantane (template), 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 heating reflux at a temperature of 40°C to form a first mixed solution, 0.006 mol of aluminum sol (aluminum source) (solid content 10wt%, pH 4, viscosity 43mPa.s, particle size 10nm), 0.88mmol of yttrium acetate (rare earth source), and 5.28mmol of diethylenetriamine pentaacetic acid pentasodium salt (chelating agent) are added to the first mixture to form a second mixture, and 0.12 mol of silica sol (silicon source) (solid content 20%, pH 3.5, density 1.5g / cm 3 ) is mixed with the second mixture, stirred until a uniform gel is formed, to form a third mixture; the mixture is placed in a polytetrafluoroethylene-lined hydrothermal reactor, hydrothermally crystallized at 180° C. for 4 days, the crystallized product is washed three times with deionized water, microwave dried at 110° C. overnight, and microwave calcined at 600° C. for 4 hours to obtain a first reaction product;

[0060] S2, adding the first reaction product to 25 mL of an aqueous solution of 1.5 mol / L ammonium nitrate, reacting for 5 h at a microwave power of 1000 W, an ultrasonic power of 800 W, and a temperature of 70° C., washing the product three times with deionized water, and drying it 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) into 12 g of 0.35 mol / L aqueous solution of copper glutamate chelate, and react for 4 h under the conditions of microwave power of 1000 W, constant ultrasonic power of 800 W, and temperature of 70 ° C. Wash the exchanged product three times with deionized water, microwave dry at 110 ° C. overnight, and microwave calcine at 500 ° C. for 2 h to obtain a rare earth-based copper molecular sieve denitrification catalyst.

[0062] Example 2

[0063] S1. The preparation steps of a rare earth-based copper molecular sieve denitrification catalyst resistant to alkali metal poisoning are as follows: S1. 0.012 mol of N,N,N-trimethylammonium adamantane, 0.010 mol of sodium alcohol and 2.45 mol of water are stirred evenly under heating reflux at a temperature of 30° C. to form a first mixed solution; 0.0088 mol of sodium aluminate, 0.5 mmol of cerium acetate and 3 mmol of (2-hydroxyethyl)ethylenediamine-N,N,N-triacetic acid trisodium salt solution are added to the first mixture to form a second mixture; 0.11 mol of silica sol (solid content: 20%, pH: 3.5, density: 1.5 g / cm 3 ) is mixed with the second mixture and stirred until a uniform gel is formed to form a third mixture; the mixture is placed in a hydrothermal reactor lined with polytetrafluoroethylene, hydrothermally crystallized at 160° C. for 4 days, the crystallized product is washed three times with deionized water, microwave dried at 110° C. overnight, and microwave calcined at 600° C. for 4 hours to obtain a first reaction product;

[0064] S2, adding the first reaction product to 20 mL of an aqueous solution of 2 mol / L ammonium chloride, reacting for 4 h at a microwave power of 800 W, an ultrasonic power of 600 W, and a temperature of 80° C., washing the product three times with deionized water, and drying it overnight at 110° C. in a microwave oven to obtain a second reaction product (ammonium-exchanged molecular sieve);

[0065] S3. Add 10 g of 0.4 mol / L copper acetate aqueous solution to the second reaction product, and react for 2 h at a microwave power of 800 W, an ultrasonic power of 600 W, and 80° C. The exchanged product was washed three times with deionized water, dried overnight at 110° C., and calcined at 500° C. for 2 h to obtain a rare earth-based copper molecular sieve denitrification catalyst.

[0066] Example 3

[0067] S1. 0.011 mol of N,N,N-trimethylammonium adamantane, 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 mixed solution; 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; 0.11 mol of silica sol (solid content of 20%, pH: 3.5, density of 1.5 g / cm 3 ) is mixed with the second mixture and stirred until a uniform gel is formed to form a third mixture; the mixture is placed in a hydrothermal reactor lined with polytetrafluoroethylene, hydrothermally crystallized at 140° C. for 3 days, the crystallized product is washed three times with deionized water, microwave dried at 110° C. overnight, and microwave calcined at 600° C. for 3 h;

[0068] S2, adding the first reaction product to 35 mL of 1 mol / L ammonium nitrate aqueous solution, reacting for 3 h under the conditions of microwave power of 900 W, ultrasonic power of 500 W, and temperature of 80 ° C, washing the product three times with deionized water, and drying it overnight at 110 ° C in a microwave to obtain a second reaction product (ammonium exchanged molecular sieve);

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

[0070] Comparative Example 1

[0071] The preparation steps of the denitration catalyst are:

[0072] S1. Add 0.012 mol of N,N,N-trimethylammonium adamantanium, 0.010 mol of sodium alkoxide, and 0.0088 mol of sodium aluminate 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 ), stirring until a uniform gel is formed, the mixture is placed in a hydrothermal reactor lined with polytetrafluoroethylene, hydrothermally crystallized at 160° C. for 4 days, the crystallized product is washed three times with deionized water, dried overnight at 110° C. in air, and calcined at 600° C. in air for 4 hours to obtain a first reaction product;

[0073] S2, adding the first reaction product to 20 mL of an aqueous solution of 2 mol / L ammonium chloride, reacting at room temperature for 4 h, washing the product three times with deionized water, and drying at 110° C. overnight to obtain a second reaction product (ammonium-exchanged molecular sieve);

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

[0077] 0.5 mmol of cerium acetate was dissolved in water, and H-type zeolite B containing CHA type was added, stirred at room temperature for 12 hours, filtered, and the resulting product was washed with deionized water, and then dried at 110°C for 24 hours to obtain zeolite B containing rare earth ions; zeolite B containing rare earth ions was added to 10 g of 0.4 mol / L copper acetate, stirred at room temperature for 12 hours, filtered, and the resulting solid product was washed with deionized water, and then dried at 100°C for 24 hours. The dried product was calcined in air at 500°C for 2 hours to obtain a copper-based zeolite containing rare earths.

[0078] Test example

[0079] The catalysts in Examples 1 to 3 and Comparative Examples 1 to 2 were tested for NH3-SCR activity, and the nitrogen oxide conversion results are shown in Table 1.

[0080] Test conditions: [NO] = 500 ppm; [NH3] = 500 ppm; [O2] = 10%; [C3H6] = 200 ppm; [CO] = 8 vol%; [H2O] = 5 vol%; N2 as balance gas; total flow rate 750 mL / min; space velocity = 100000 h -1 .

[0081] Table 1

[0082]

[0083] The catalysts in Examples 1 to 3 and Comparative Examples 1 to 2 were prepared as alkali-poisoned catalysts, and NH3-SCR activity tests were performed. The results of nitrogen oxide conversion rates are shown in Table 2. The alkali poisoning method is as follows:

[0084] Take 5g of the catalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 2, dissolve 0.39g of KNO3 in deionized water, and then drop the KNO3 aqueous solution onto the molecular sieve using an equal volume impregnation method, impregnate at room temperature for 6h, microwave dry at 110°C overnight, and microwave roast at 500°C for 2h to obtain K + Catalyst with 3% K / gcat loading.

[0085] Test conditions: [NO] = 500 ppm; [NH3] = 500 ppm; [CO2] = 8%; [C3H6] = 200 ppm; [O2] = 10%; [H2O] = 5 vol%; N2 as balance gas; total flow rate 750 mL / min; space velocity = 100000 h -1 .

[0086] Table 2

[0087]

[0088] Figure 1 These are the EPR graphs 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 These are XPS graphs of the catalysts prepared in Example 2 and Comparative Example 2 after being poisoned, where the fresh ones are before being poisoned.

[0090] From Tables 1 to 2 and Figures 1-2 From the content we can see:

[0091] In Table 1, before alkali poisoning, the timing of adding rare earth elements will not affect its SCR performance. However, in the SCR catalytic activity data after 3% K poisoning (Table 2), by comparing Examples 1 to 3 with Comparative Example 1, it can be seen that the nitrogen oxide conversion rate of Comparative Example 1 at 250°C, 300°C, 350°C and 400°C is much lower than that of Examples 1 to 3 (Table 2), which indicates that after alkali metal K poisoning, by adding rare earth in the process of synthesizing molecular sieve, it has excellent anti-K poisoning performance.

[0092] By comparing Examples 1 to 3 with Comparative Example 2, it can be seen that the nitrogen oxide conversion rate of Comparative Example 2 at 250°C, 300°C, 350°C and 400°C is much lower than that of Examples 1 to 3 (Table 2), which indicates that after alkali metal K poisoning, the rare earth-based copper molecular sieve synthesized by adding rare earth in the process of synthesizing the molecular sieve has better anti-K poisoning performance than the one synthesized by adding rare earth on the basis of the molecular sieve.

[0093] Comparing Comparative Example 1 with Comparative Example 2, it can be seen that the nitrogen oxide 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 molecular sieve, and rare earth is not easy to interact strongly with active copper. At the same time, a part of the active copper sites are covered by the formed rare earth oxide, resulting in a decrease in anti-K activity.

[0094] The reason is that adding rare earth ions during the synthesis of molecular sieves can make the rare earth ions react with the active Cu 2+ There is a strong interaction between them, which inhibits the inactive CuO xThe generation of alkali metal poisoning resistance is improved. Figure 2 ) It can be seen that the rare earth Ce is added later on the basis of the molecular sieve, and its Ce mainly exists on the catalyst surface in the form of CeO2, which has a weak interaction with the active copper in the ring, resulting in its poor resistance to K poisoning.

[0095] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all 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.

2. The preparation method according to claim 1, characterized in that: 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 masses of the aluminum source and the silicon source to the copper source is 1:0.5-8.

3. The preparation method according to claim 1, characterized in that: 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 tri-metasulfonic acid sodium salt, ethylenediaminetetraacetic acid disodium magnesium salt, N-methyliminodiacetic acid disodium salt, 1,3-benzoxazol-2-yl acetic acid sodium salt, 6-phosphogluconate trisodium salt, and N-(2-hydroxyethyl)ethylenediamine-N,N and 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, silicon oxide, 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 includes at least one of copper nitrate, copper sulfate, copper chloride, copper gluconate, copper propionate, copper acetate, copper isopropionate and copper glutamate chelate.

4. The preparation method according to claim 3, characterized in that: The inorganic base includes sodium hydroxide and / or potassium hydroxide; the organic base includes at least one of sodium alkoxide, potassium alkoxide and tetraethylammonium hydroxide.

5. 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.

6. 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 1-24h; the temperature of the second microwave ultrasonic reaction is 40-90°C, and the time is 1-24h; 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.

7. 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 calcining temperature is 450-800° C., and the time is 1-5 hours.

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

9. 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 8.

10. Use of the rare earth-based copper molecular sieve denitration catalyst resistant to alkali metal poisoning as claimed in claim 9 for NH3-SCR in an environment containing alkali metal oxides.

Images