Preparation method and application of multilayer wear-controllable denitration catalyst

Abstract

The invention relates to the technical field of denitration catalysts, and provides a preparation method and application of a multi-layer controllable-abrasion denitration catalyst, the denitration catalyst with good denitration activity and poisoning resistance can be prepared through the preparation method, the stability is good in the long-term application process, the preparation technology is simple, and the production period is short. The preparation method comprises the following steps: S1, taking a denitration catalyst as a matrix, coating the matrix with intermediate layer slurry, then carrying out first drying at 40-80 DEG C, then heating to 150-200 DEG C, and carrying out second drying; after drying is completed, first roasting is conducted at the temperature of 250-300 DEG C, and then the temperature is increased to 550-650 DEG C for second roasting; s2, uniformly dipping the sample obtained in the step S1 in an outer layer solution, then carrying out third drying at 40-80 DEG C, then heating to 150-200 DEG C, and carrying out fourth drying; after drying is completed, third roasting is conducted at the temperature of 250-300 DEG C, and then the temperature is increased to 350-650 DEG C for fourth roasting.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of denitration catalyst, in particular to a preparation method and application of a multi-layer controllable abrasion denitration catalyst. BACKGROUND

[0002] The selective catalytic reduction (SCR) denitration technology is a kind of efficient, reliable and mature flue gas denitration technology, and the denitration catalyst is a key component of the technology. Since the implementation of the flue gas denitration in the thermal power and non-electricity industries, millions of tons of denitration catalysts have been put into use. In the long-term operation process, the denitration catalyst will gradually lose the denitration activity due to the long-term erosion and accumulation of the poisoning element substances such as alkali metals, alkaline earth metals, heavy metals and arsenic in the flue gas.

[0003] For the honeycomb type monolithic denitration catalyst, how to provide a denitration catalyst preparation technology capable of improving the anti-poisoning performance of the denitration catalyst, prolonging the service life and guaranteeing excellent denitration activity is one of the technical difficulties to be broken through in the field. SUMMARY

[0004] In view of at least one deficiency existing in the prior art, the present application provides a preparation method and application of a multi-layer controllable abrasion denitration catalyst. The preparation method provided by the present application can prepare a denitration catalyst which has good initial denitration activity and good activity stability in long-term application, and the preparation process is simple and the production cycle is short.

[0005] In order to achieve the purpose, the present application provides the following technical solutions: The present application provides a preparation method of a multi-layer controllable abrasion denitration catalyst, which comprises the following steps: S1, using a denitration catalyst as a substrate, coating an intermediate layer slurry on the substrate, then performing first drying at 40-80 DEG C, then heating to 150-200 DEG C to perform second drying; after drying, performing first calcination at 250-300 DEG C, then heating to 550-650 DEG C to perform second calcination; The carrier of the denitration catalyst as the substrate is one or more of titanium dioxide, silicon dioxide and aluminum trioxide; The intermediate layer slurry is prepared by using the following components by mass: 60-80 parts of titanium dioxide, 10-20 parts of a first main active component precursor, 10-20 parts of a first auxiliary active component precursor and 100-400 parts of deionized water; S2, uniformly immersing the sample obtained in step S1 in an outer layer solution, then performing third drying at 40-80 DEG C, then heating to 150-200 DEG C to perform fourth drying; after drying, performing third calcination at 250-300 DEG C, then heating to 350-650 DEG C to perform fourth calcination; The outer layer solution comprises the following components by mass fraction: 50-100 parts of the second main active component precursor, 0-50 parts of the second auxiliary active component precursor, 50-100 parts of the cosolvent, and 50-100 parts of deionized water.

[0006] Preferably, in step S1, the first main active component precursor in the intermediate layer slurry is selected from one or more of ammonium metavanadate and vanadyl oxalate; And / or, in step S1, the first auxiliary active component precursor in the intermediate layer slurry is selected from one or more of ammonium metatungstate, ammonium paratungstate, ammonium heptamolybdate, cerium nitrate, and copper nitrate; And / or, in step S2, the second main active component precursor in the outer layer solution is selected from one or more of ammonium metavanadate and vanadyl oxalate; And / or, in step S2, the second auxiliary active component precursor in the outer layer solution is selected from one or more of ammonium metatungstate, ammonium paratungstate, ammonium heptamolybdate, cerium nitrate, and copper nitrate; And / or, in step S2, the cosolvent is selected from one or more of oxalic acid, sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid, and preferably, the concentration of the sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid is 1-10 wt%.

[0007] Preferably, in step S1, the main component of the denitration catalyst as the substrate comprises the following components by mass fraction: 87-96% of the carrier, 4-8% of the main active component, and 0-5% of the auxiliary active component.

[0008] Preferably, in the substrate, the main active component is selected from one or more of vanadium pentoxide, tungsten trioxide, and molybdenum trioxide; Preferably, in the substrate, the auxiliary active component is selected from one or more of cerium oxide, copper oxide, manganese oxide, iron oxide, antimony oxide, niobium oxide, cobalt oxide, nickel oxide, zinc oxide, and tin oxide.

[0009] Further, the substrate is a honeycomb-type denitration catalyst.

[0010] Preferably, in step S1, the first drying time is 1-2 h; And / or, in step S1, the second drying time is 2-4 h; And / or, in step S1, after completing the first drying, the second drying is performed at a rate of 2-5 ℃ / min to 150-200 ℃.

[0011] Preferably, in step S1, the first calcination is performed at a rate of 2-5 ℃ / min to 250-300 ℃; And / or, in step S1, the second calcination is performed at a rate of 2-5℃ / min to the temperature of 550-650℃; And / or, in step S1, the second calcination is performed at a rate of 2-5℃ / min to the temperature of 550-650℃; And / or, in step S1, the second calcination is performed at a rate of 2-5℃ / min to the temperature of 550-650℃;

[0012] Preferably, in step S2, the third drying is performed at a rate of 2-5℃ / min to the temperature of 150-200℃; And / or, in step S2, the fourth drying is performed at a rate of 2-5℃ / min to the temperature of 150-200℃; And / or, in step S2, the fourth drying is performed at a rate of 2-5℃ / min to the temperature of 150-200℃;

[0013] Preferably, in step S2, the third calcination is performed at a rate of 2-5℃ / min to the temperature of 250-300℃; And / or, in step S2, the third calcination is performed at a rate of 2-5℃ / min to the temperature of 250-300℃; And / or, in step S2, the fourth calcination is performed at a rate of 2-5℃ / min to the temperature of 350-650℃; And / or, in step S2, the fourth calcination is performed at a rate of 2-5℃ / min to the temperature of 350-650℃;

[0014] Preferably, in step S1, the mass of the intermediate layer formed after the second calcination is 4-10% of the mass of the substrate; And / or, in step S2, the mass of the load formed after the fourth calcination by impregnating the outer layer solution is 1-3% of the mass of the sample obtained in step S1.

[0015] The application also provides the use of the multilayer controllable abrasion denitration catalyst prepared by the preparation method in flue gas denitration treatment.

[0016] The technical scheme provided by the application has the following beneficial effects: The multilayer controllable abrasion denitration catalyst prepared by the method comprises a substrate, an intermediate active component oxide layer and an outer active component oxide layer from inside to outside, forming a three-layer denitration structure. The catalyst can gradually peel off layer by layer and expose fresh catalyst layers as the running time continues and the flue gas is scoured. The catalyst has a moderate peeling rate and can maintain a relatively stable peeling rate in long-term application. The catalyst has a good initial denitration activity and a good activity stability in long-term application, and can also have a good resistance to poisoning. DETAILED DESCRIPTION

[0017] For the purpose of understanding the present application, the present application will be further described in conjunction with the examples. It should be understood that the following examples are only for a better understanding of the present application, and do not mean that the present application is limited to the following examples only.

[0018] Unless otherwise defined, 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 application belongs. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and should not be construed as indicating or implying relative importance.

[0019] The present application provides a preparation method of a multi-layer controllable wear denitration catalyst, comprising the following steps: S1, taking a denitration catalyst as a substrate, coating an intermediate layer slurry on the substrate, then performing first drying at 40-80℃ (such as 40, 60, 80℃, etc.), then increasing the temperature to 150-200℃ (such as 150, 170, 200℃, etc.) to perform second drying; after drying, performing first calcination at 250-300℃ (such as 250, 280, 300℃, etc.), then increasing the temperature to 550-650℃ (such as 550, 570, 600, 630, 650℃, etc.) to perform second calcination; Among them, the carrier of the denitration catalyst as the substrate is one or more of titanium dioxide, silicon dioxide and aluminum trioxide; The intermediate layer slurry is prepared by using the following components by mass: 60-80 parts (such as 60, 70, 80 parts, etc.) of titanium dioxide, 10-20 parts (such as 10, 15, 20 parts, etc.) of first main active component precursor, 10-20 parts (such as 10, 15, 20 parts, etc.) of first auxiliary active component precursor, and 100-400 parts (such as 100, 200, 300, 400 parts, etc.) of deionized water; S2, uniformly immersing the sample obtained in step S1 in an outer layer solution, then performing third drying at 40-80℃ (such as 40, 60, 80℃, etc.), then increasing the temperature to 150-200℃ (such as 150, 170, 200℃, etc.) to perform fourth drying; after drying, performing third calcination at 250-300℃ (such as 250, 280, 300℃, etc.), then increasing the temperature to 350-650℃ (such as 350, 400, 450, 500, 550, 600, 650℃, etc.) to perform fourth calcination; The outer layer solution comprises the following components by mass fraction: 50-100 parts (for example, 50, 70, 80, 100 parts, etc.) of the second main active component precursor, 0-50 parts (for example, 0, 10, 20, 30, 40, 50 parts, etc.) of the second auxiliary active component precursor, 50-100 parts (for example, 50, 70, 80, 100 parts, etc.) of the cosolvent, and 50-100 parts (for example, 50, 70, 80, 100 parts, etc.) of deionized water.

[0020] The catalyst obtained by the method of the present application comprises, from the inside out, a substrate, an intermediate active component oxide layer, and an outer active component oxide layer, forming a three-layer denitration structure. The catalyst can gradually peel off layer by layer and expose fresh catalyst layers as the running time continues and the flue gas is continuously scoured by fly ash, ensuring long-lasting and optimal denitration activity, good resistance to poisoning, and an extended service life of the denitration catalyst. The preparation method of the multi-layer controllable wear denitration catalyst provided by the present application has a simple preparation process and a relatively short production cycle.

[0021] In the method of the present application, the denitration catalyst with one or more of titanium dioxide, silicon dioxide, and aluminum trioxide as the carrier is used as the substrate. The intermediate layer slurry formed by the above-mentioned formula is coated on the substrate, and the titanium dioxide carrier is combined with the other components in the above-mentioned ratio in the intermediate layer slurry. The first / second drying and the first / second calcination are performed according to the above-mentioned step-by-step drying and calcination procedures. Then, the outer layer solution formed by the above-mentioned formula is impregnated on the substrate, and the third / fourth drying and the third / fourth calcination are performed according to the above-mentioned step-by-step drying and calcination procedures. The three-layer catalyst prepared by the process of the present application has an intermediate layer slurry treated by the above-mentioned drying and calcination procedures, which forms a valence bond structure with the denitration catalyst substrate, but is weaker than the mechanical strength of the denitration catalyst substrate itself. The outer layer solution impregnated on the basis is treated by the above-mentioned drying and calcination procedures, which is converted into an active component oxide and forms a weak valence bond structure with the intermediate slurry layer, but is weaker than the mechanical strength between the intermediate slurry layer and the denitration catalyst substrate. The catalyst prepared by the present application has a multi-layer denitration structure with a relatively moderate peeling rate, and the peeling rate is relatively stable in long-term application. The catalyst can gradually peel off layer by layer and expose fresh catalyst layers as the flue gas is continuously scoured by fly ash, which is beneficial to maintaining the excellent denitration activity of the catalyst. The gradual peeling off during use can remove the attached poisoning elements, and the catalyst has good resistance to poisoning. The catalyst of the present application can balance the good denitration activity and has good activity stability in long-term application.

[0022] In the preparation method, the denitration catalyst substrate with one or more of the carriers being titanium dioxide, silicon dioxide, and aluminum trioxide is prepared by combining and formulating the intermediate layer slurry with the above-mentioned amounts of titanium dioxide as the carrier and the first main active component precursor, the first auxiliary active component precursor, and deionized water, and the outer layer solution with the above-mentioned amounts of the second main active component precursor, the second auxiliary active component precursor, the cosolvent, and deionized water, and the obtained three-layer structure catalyst has a relatively suitable bonding strength between the layers, can take into account moderate and relatively stable shedding rate and good denitration activity, and can realize updating at a suitable peeling rate during use.

[0023] Preferably, in step S1, the first main active component precursor in the intermediate layer slurry is selected from one or more of ammonium metavanadate and vanadyl oxalate; preferably, in step S1, the first auxiliary active component precursor in the intermediate layer slurry is selected from one or more of ammonium metatungstate, ammonium paratungstate, ammonium heptamolybdate, cerous nitrate, and cupric nitrate. The use of the above-mentioned preferred first main active component precursor and first auxiliary active component precursor is conducive to obtaining better denitration activity.

[0024] In step S1, the intermediate layer slurry used can be obtained by mixing the required components and then grinding in a slurry preparation device such as a sand mill to obtain a homogeneous slurry, for example, in a sand mill for 30 min.

[0025] Preferably, in step S2, the second main active component precursor in the outer layer solution is selected from one or more of ammonium metavanadate and vanadyl oxalate; preferably, in step S2, the second auxiliary active component precursor in the outer layer solution is selected from one or more of ammonium metatungstate, ammonium paratungstate, ammonium heptamolybdate, cerous nitrate, and cupric nitrate; and preferably, in step S2, the cosolvent is selected from one or more of oxalic acid, sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid, wherein the concentration of the sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid is preferably 1-10 wt%, for example, 1, 3, 5, 7, 10 wt%, etc. The use of the above-mentioned preferred second main active component precursor and second auxiliary active component precursor is conducive to obtaining better denitration activity.

[0026] In step S2, the outer layer solution used can be obtained by mixing and heating to dissolve the components required for the outer layer solution.

[0027] In step S1, the denitration catalyst as the substrate has a carrier of one or more of titanium dioxide, silicon dioxide, and aluminum trioxide. The substrate can be a ready-made denitration catalyst product, or can be prepared by a preparation process known in the art (for example, but not limited to, CN102755887B “Preparation method of SCR denitration catalyst suitable for high-temperature flue gas conditions”, CN102755898B “SCR denitration catalyst suitable for high-dust flue gas conditions and preparation method thereof”, CN102764644B “Preparation method of SCR denitration catalyst suitable for high-calcium or high-sulfur flue gas conditions”, etc.), and there is no particular limitation. Preferably, in step S1, the main components of the denitration catalyst as the substrate include: the carrier 87-96% (for example, 87, 90, 96%, etc.), the main active component 4-8% (for example, 4, 5, 6, 7, 8%, etc.), and the auxiliary active component 0-5% (for example, 0, 1, 2, 3, 4, 5%, etc.), all in mass percentage.

[0028] Preferably, in the substrate, the main active component is selected from one or more of vanadium pentoxide, tungsten trioxide, and molybdenum trioxide; and preferably, in the substrate, the auxiliary active component is selected from one or more of cerium oxide, copper oxide, manganese oxide, iron oxide, antimony oxide, niobium oxide, cobalt oxide, nickel oxide, zinc oxide, and tin oxide.

[0029] Further, the substrate in the present application is a honeycomb-type denitration catalyst.

[0030] Preferably, in step S1, the first drying time is 1-2h; preferably, in step S1, after the first drying is completed, the second drying is performed at a rate of 2-5℃ / min to 150-200℃; preferably, in step S1, the second drying time is 2-4h. Preferably, in step S1, the first calcination is performed at a rate of 2-5℃ / min to 250-300℃; preferably, in step S1, the first calcination time is 2-4h; preferably, in step S1, the second calcination is performed at a rate of 2-5℃ / min to 550-650℃; preferably, in step S1, the second calcination time is 3-5h.

[0031] Preferably, in step S2, the third drying time is 1-3h; preferably, in step S2, the fourth drying is performed at a rate of 2-5℃ / min to 150-200℃; preferably, in step S2, the fourth drying time is 2-3h.

[0032] Preferably, in step S2, the third calcination is performed at a rate of 2-5℃ / min to the temperature of 250-300℃; preferably, in step S2, the time of the third calcination is 2-4h; preferably, in step S2, the fourth calcination is performed at a rate of 2-5℃ / min to the temperature of 350-650℃; preferably, in step S2, the time of the fourth calcination is 3-5h.

[0033] Preferably, in step S1, the mass of the intermediate layer formed from the intermediate layer slurry after the second calcination is 4-10%, for example 4, 5, 6, 7, 8, 9, 10%, etc. of the mass of the substrate. Preferably, in step S2, the mass of the load formed from the impregnated outer layer solution on the sample obtained in step S1 after the fourth calcination is 1-3%, for example 1, 2, 3%, etc. of the mass of the sample obtained in step S1.

[0034] The application also provides the use of the multilayer controllable wear denitration catalyst prepared by the preparation method described above in flue gas denitration treatment.

[0035] The application will be further described by examples below, but should not be understood as limiting the application to the examples.

[0036] If the specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions can be used. If the reagents or instruments used are not specified by the manufacturer, they are conventional products that can be obtained by purchase.

[0037] Detection method: Exfoliation rate: refer to GB / T 34496-2017 "Gas heavy-duty vehicle exhaust purification catalyst"; Denitration activity: refer to GB / T 31587-2015 "Honeycomb flue gas denitration catalyst".

[0038] In the performance detection of the following examples and comparative examples, "application for 600h" means that the denitration catalyst is applied in a flue gas pilot plant for 600h, and the flue gas conditions are: 380℃, flue gas flow 40000m 3 / h, dust content 30g / m 3 , NOx content 200mg / m 3 , NH3 content 200mg / m 3 .

[0039] In the following examples, the denitration catalyst used as the substrate is a conventional commercially available denitration catalyst product, the brand is Longyuan catalyst, the catalyst is in the form of a honeycomb long strip, the specification is 18*18 holes, and the main components of the denitration catalyst include, mass percentage: carrier 92%, main active component 6%, and auxiliary active component 2%. Based on the mass proportion in the catalyst, the carrier component is 86% titanium dioxide, 5% silicon dioxide, 1% aluminum trioxide; the main active component is 1% vanadium pentoxide, 5% tungsten trioxide; the secondary active component is 1% cerium oxide, 1% niobium oxide.

[0040] In the following examples, the parts of the materials involved refer to mass parts if not specifically stated, which will not be elaborated hereinafter.

[0041] Example 1 (1) Preparation of the intermediate layer slurry: Take 70 parts of titanium dioxide, 10 parts of the first main active component precursor, 20 parts of the first secondary active component precursor, and 200 parts of deionized water, and add them to a sand mill. Rotate at a speed of 2500 r / min for 30 min to prepare a homogeneous slurry. The first main active component precursor is ammonium metavanadate; the first secondary active component precursor is: 15 parts of ammonium metatungstate, 5 parts of heptamolybdate.

[0042] (2) Preparation of the outer layer solution: Take 50 parts of the second main active component precursor, 50 parts of the second secondary active component precursor, 100 parts of the cosolvent, and 100 parts of deionized water, and heat to 60°C for dissolution. The second main active component precursor is ammonium metavanadate; the second secondary active component precursor is: 25 parts of ammonium metatungstate, 25 parts of heptamolybdate; the cosolvent is oxalic acid.

[0043] (3) Intermediate layer slurry coating and drying and calcination treatment: Use a coating machine to uniformly coat the intermediate layer slurry in step (1) onto the denitration catalyst as the substrate; then perform first drying at 60°C for 2h; then perform second drying by increasing the temperature to 200°C at a rate of 4°C / min, and constant temperature drying for 3h; After drying, perform first calcination by increasing the temperature to 300°C at a rate of 4°C / min, and constant temperature calcination for 2h; then perform second calcination by increasing the temperature to 600°C at a rate of 4°C / min, and constant temperature calcination for 4h, to obtain a denitration catalyst coated with an intermediate layer. The mass of the formed intermediate layer is 7% of the mass of the substrate.

[0044] (4) Outer layer solution impregnation and drying and calcination treatment: Soak the denitration catalyst coated with the intermediate layer obtained in step (3) in the outer layer solution of step (2) to uniformly impregnate the outer layer solution onto the denitration catalyst coated with the intermediate layer; then perform third drying at 60°C for 2h; then perform fourth drying by increasing the temperature to 150°C at a rate of 4°C / min, and constant temperature drying for 3h; After drying, the third calcination is performed at a temperature increasing rate of 4℃ / min to 250℃, and the temperature is kept for 2h; then the fourth calcination is performed at a temperature increasing rate of 4℃ / min to 400℃, and the temperature is kept for 4h, to obtain the multi-layer controllable abrasion denitration catalyst. By weight calculation, the weight percentage increase of the final multi-layer controllable abrasion denitration catalyst compared with the denitration catalyst coated with the intermediate layer obtained in step (3) is 2%.

[0045] Experimental results:

[0046] The catalyst prepared in Example 1 has a moderate shedding rate, can realize shedding and updating during use, and can still maintain good denitration activity after 600h of pilot application, the shedding rate and the denitration activity are relatively stable, the increase of poisoning elements is small, and the catalyst has good anti-poisoning performance.

[0047] Example 2 (1) Preparation of intermediate layer slurry: 80 parts of titanium dioxide, 10 parts of first main active component precursor, 10 parts of first auxiliary active component precursor and 100 parts of deionized water were weighed and added into a sand mill, and the sand mill was rotated at a speed of 2000r / min for 40min to prepare a homogeneous slurry; The first main active component precursor is vanadyl oxalate, and the first auxiliary active component precursor is 5 parts of ammonium paratungstate and 5 parts of cerium nitrate.

[0048] (2) Preparation of outer layer solution: 80 parts of second main active component precursor, 40 parts of second auxiliary active component precursor, 80 parts of cosolvent and 90 parts of deionized water were weighed and heated to 40℃ for dissolution; The second main active component precursor is vanadyl oxalate, and the second auxiliary active component precursor is 20 parts of ammonium metatungstate and 20 parts of ammonium heptamolybdate; the cosolvent is oxalic acid.

[0049] (3) Intermediate layer slurry coating and drying and calcination treatment: The intermediate layer slurry in step (1) was uniformly coated on the denitration catalyst as the substrate by using a coating machine; then first drying was performed at 50℃, and the drying time was 2h; then second drying was performed at a temperature increasing rate of 3℃ / min to 150℃, and the temperature was kept for 4h; After drying, the first calcination was performed at a temperature increasing rate of 2℃ / min to 250℃, and the temperature was kept for 4h; then the second calcination was performed at a temperature increasing rate of 5℃ / min to 550℃, and the temperature was kept for 5h, to obtain the denitration catalyst coated with the intermediate layer. The mass of the formed intermediate layer is 6% of the mass of the substrate.

[0050] (4) Outer layer solution impregnation and drying and calcination treatment: The intermediate layer coated denitration catalyst obtained in step (3) is soaked in the outer layer solution of step (2) to uniformly impregnate the outer layer solution onto the intermediate layer coated denitration catalyst; then third drying is performed at 60℃ for 3h; then fourth drying is performed at 3℃ / min to 200℃, and constant temperature drying is performed for 2h; After drying, third calcination is performed at 5℃ / min to 300℃, and constant temperature calcination is performed for 2h; then fourth calcination is performed at 3℃ / min to 500℃, and constant temperature calcination is performed for 4h, to obtain the multi-layer controllable wear denitration catalyst. By weighing calculation, the weight gain percentage of the finally obtained multi-layer controllable wear denitration catalyst compared with the intermediate layer coated denitration catalyst obtained in step (3) is 1%.

[0051] Experimental results:

[0052] Example 3 (1) Preparation of intermediate layer slurry: Titanium dioxide 60 parts, first main active component precursor 20 parts, first auxiliary active component precursor 20 parts, and deionized water 350 parts are weighed and added into a sand mill, which is rotated at a speed of 1500r / min for 60min to prepare a homogeneous slurry; The first main active component precursor is ammonium metavanadate; the first auxiliary active component precursor is 10 parts of ammonium metatungstate and 10 parts of ammonium heptamolybdate.

[0053] (2) Preparation of outer layer solution: Second main active component precursor 100 parts, second auxiliary active component precursor 20 parts, cosolvent 50 parts, and deionized water 60 parts are weighed and heated to 80℃ for dissolution; The second main active component precursor is ammonium metavanadate; the second auxiliary active component precursor is 10 parts of ammonium metatungstate and 10 parts of cerium nitrate; and the cosolvent is oxalic acid.

[0054] (3) Intermediate layer slurry coating and drying and calcination treatment: The intermediate layer slurry in step (1) is uniformly coated onto the denitration catalyst as the substrate using a coating machine; then first drying is performed at 70℃ for 2h; then second drying is performed at 5℃ / min to 180℃, and constant temperature drying is performed for 2h; After drying, first calcination is performed at 5℃ / min to 300℃, and constant temperature calcination is performed for 3h; then second calcination is performed at 3℃ / min to 650℃, and constant temperature calcination is performed for 3h, to obtain the intermediate layer coated denitration catalyst. The mass of the formed intermediate layer is 8% of the mass of the substrate.

[0055] (4) outer layer solution impregnation and drying calcination treatment: The intermediate layer coated denitration catalyst obtained in step (3) is soaked in the outer layer solution of step (2), so that the outer layer solution is uniformly impregnated on the intermediate layer coated denitration catalyst; then third drying is carried out at 60℃, and the drying time is 3h; then fourth drying is carried out according to 5℃ / min to 180℃, and constant temperature drying is carried out for 3h; After drying, the temperature is raised to 250℃ according to 2℃ / min, and third calcination is carried out, and the constant temperature calcination is carried out for 4h; then the temperature is raised to 600℃ according to 5℃ / min, and fourth calcination is carried out, and the constant temperature calcination is carried out for 3h, to obtain a multi-layer controllable wear denitration catalyst. By weighing calculation, the weight gain percentage of the finally obtained multi-layer controllable wear denitration catalyst compared with the intermediate layer coated denitration catalyst obtained in step (3) is 3%.

[0056] Experimental results:

[0057] Comparative Example 1 Reference is made to Example 1, except that: In step (1), the titanium dioxide in the intermediate layer slurry is replaced by aluminum oxide.

[0058] Experimental results:

[0059] Comparative Example 2 Reference is made to Example 1, except that: In step (1), the amount of each component in the intermediate layer slurry is as follows: titanium dioxide 50 parts, first main active component precursor 5 parts, first auxiliary active component precursor 5 parts (3.5 parts of ammonium metatungstate, 1.5 parts of ammonium heptamolybdate), deionized water 50 parts.

[0060] Experimental results:

[0061] Comparative Example 3 Reference is made to Example 1, except that: In step (2), the amount of each component in the outer layer solution is as follows: second main active component precursor 130 parts, second auxiliary active component precursor 60 parts (30 parts of ammonium metatungstate, 30 parts of ammonium heptamolybdate), cosolvent 150 parts, deionized water 150 parts.

[0062] Experimental results:

[0063] Comparative Example 4 Reference is made to Example 1, except that: In step (3), the first drying is omitted, and the second drying is directly performed at a temperature increasing rate of 4°C / min to 200°C.

[0064] In step (4), the third drying is omitted, and the fourth drying is directly performed at a temperature increasing rate of 4°C / min to 150°C, and the constant temperature drying is performed for 3h.

[0065] Experimental results:

[0066] Comparative Example 5 Comparative Example 1 is referred to, except that: In step (3), after the first calcination is completed, the second calcination is performed at a temperature increasing rate of 4°C / min to 450°C.

[0067] Experimental results:

[0068] Comparative Example 6 Comparative Example 1 is referred to, except that: In step (4), the third calcination is omitted, and the fourth calcination is directly performed at a temperature increasing rate of 4°C / min to 400°C.

[0069] Experimental results:

[0070] Compared with the comparative examples, the catalyst prepared in the embodiments has higher initial denitration activity, and has better denitration activity stability and smaller denitration activity reduction in the long-term application process. In addition, compared with the comparative examples, the catalyst prepared in the embodiments has a moderate shedding rate, and the shedding rate remains relatively stable in the long-term application process. Meanwhile, the catalyst provided in the embodiments can have good resistance to poisoning.

[0071] In Comparative Examples 1, 2, 4 and 5, the shedding rate is relatively high, the denitration activity is relatively low, the shedding rate increases greatly in the long-term application process, the mass loss of the catalyst caused by erosion in the long-term application is relatively large, and the denitration activity greatly reduces in the long-term application process. In Comparative Examples 3 and 6, the denitration activity is relatively low, and the denitration activity greatly reduces in the long-term application process; the shedding rate greatly increases in the long-term application process, and the mass loss of the catalyst caused by erosion in the long-term application is relatively large.

[0072] It is easily understood that the above embodiments are only examples for clearly illustrating the present application, and do not mean that the present application is limited to this. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and impossible to exhaust all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for preparing a multilayer controllable abrasion denitrification catalyst, characterized in that, Includes the following steps: S1. Using a denitrification catalyst as a substrate, an intermediate layer slurry is coated onto the substrate, and then the substrate is dried at 40-80℃ for the first time, and then dried at 150-200℃ for the second time. After drying, the substrate is calcined at 250-300℃ for the first time, and then calcined at 550-650℃ for the second time. The support for the denitrification catalyst, which serves as the matrix, is one or more of titanium dioxide, silicon dioxide, and aluminum oxide. The intermediate layer slurry is prepared by comprising the following components in parts by weight: 60-80 parts of titanium dioxide, 10-20 parts of the first main active component precursor, 10-20 parts of the first secondary active component precursor, and 100-400 parts of deionized water. S2. The sample obtained in step S1 is uniformly immersed in the outer layer solution, and then dried at 40-80℃ for the third time, and then dried at 150-200℃ for the fourth time. After drying, the sample is calcined at 250-300℃ for the third time, and then calcined at 350-650℃ for the fourth time. The outer layer solution comprises the following components in parts by weight: 50-100 parts of the second main active component precursor, 0-50 parts of the second secondary active component precursor, 50-100 parts of the cosolvent, and 50-100 parts of deionized water.

2. The preparation method according to claim 1, characterized in that, In step S1, the first main active component precursor in the intermediate layer slurry is selected from one or more of ammonium metavanadate and vanadium oxalate. And / or, in step S1, the first secondary active component precursor in the intermediate layer slurry is selected from one or more of ammonium metatungstate, ammonium paratungstate, ammonium heptamolybdate, cerium nitrate, and copper nitrate; And / or, in step S2, the second main active component precursor in the outer layer solution is selected from one or more of ammonium metavanadate and vanadium oxalate; And / or, in step S2, the second sub-active component precursor in the outer layer solution is selected from one or more of ammonium metatungstate, ammonium paratungstate, ammonium heptamolybdate, cerium nitrate, and copper nitrate; And / or, in step S2, the co-solvent is selected from one or more of oxalic acid, sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid, preferably, the concentration of sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid is 1-10 wt%.

3. The preparation method according to any one of claims 1-2, characterized in that, In step S1, the main components of the denitrification catalyst, which serves as the matrix, include the following components by mass percentage: 87-96% of the support, 4-8% of the main active component, and 0-5% of the secondary active component. Preferably, in the matrix, the main active component is selected from one or more of vanadium pentoxide, tungsten trioxide, and molybdenum trioxide; Preferably, in the matrix, the secondary active component is selected from one or more of cerium oxide, copper oxide, manganese oxide, iron oxide, antimony oxide, niobium oxide, cobalt oxide, nickel oxide, zinc oxide, and tin oxide.

4. The preparation method according to any one of claims 1-3, characterized in that, The substrate is a honeycomb denitrification catalyst.

5. The preparation method according to claim 4, characterized in that, In step S1, the first drying time is 1-2 hours; And / or, in step S1, the second drying time is 2-4 hours; And / or, in step S1, after the first drying is completed, the temperature is increased to 150-200°C at a rate of 2-5°C / min to perform the second drying.

6. The preparation method according to claim 4, characterized in that, In step S1, the temperature is increased to 250-300℃ at a rate of 2-5℃ / min to perform the first calcination; And / or, in step S1, the first calcination time is 2-4 hours; And / or, in step S1, the temperature is increased to 550-650°C at a rate of 2-5°C / min to perform the second calcination; And / or, in step S1, the second calcination time is 3-5 hours.

7. The preparation method according to claim 4, characterized in that, In step S2, the third drying time is 1-3 hours; And / or, in step S2, the fourth drying is performed by raising the temperature to 150-200°C at a rate of 2-5°C / min; And / or, in step S2, the fourth drying time is 2-3 hours.

8. The preparation method according to claim 4, characterized in that, In step S2, the temperature is increased to 250-300℃ at a rate of 2-5℃ / min to carry out the third calcination; And / or, in step S2, the third calcination time is 2-4 hours; And / or, in step S2, the fourth calcination is performed by heating to 350-650°C at a rate of 2-5°C / min; And / or, in step S2, the fourth calcination time is 3-5 hours.

9. The preparation method according to any one of claims 1-3, characterized in that, In step S1, the mass of the intermediate layer formed after the second calcination is 4-10% of the mass of the substrate; And / or, in step S2, after the fourth calcination, the mass of the loading formed by impregnating the outer layer solution is 1-3% of the mass of the sample obtained in step S1.

10. The application of the multilayer controllable abrasion denitrification catalyst prepared by the preparation method according to any one of claims 1-9 in flue gas denitrification treatment.

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