Preparation method of inner wall surface loaded honeycomb SCR (Selective Catalytic Reduction) denitration catalyst

Abstract

The invention discloses a preparation method of an inner wall surface loaded honeycomb SCR denitration catalyst, and relates to the technical field of catalysts. The preparation method of the inner wall surface loaded honeycomb SCR denitration catalyst comprises the following steps: preparing the carrier, loading, drying and calcining. The carrier part of the catalyst product does not contain or contains a small amount of active substances, the production efficiency is high, and the product qualification rate is high; an additional calcining process is not needed; according to the present invention, the active component is loaded on the inner wall surface of the honeycomb pore channel of the honeycomb carrier in the permeation manner, such that the overall consumption of the active component can be effectively reduced, the SO2 oxidation side reaction can be reduced, the secondary pollution, the equipment blocking and other conditions can be avoided, and the production cost can be easily saved, the production efficiency can be easily improved, and the product performance quality can be easily improved.

Description

Technical Field

[0001] The present application relates to the field of catalyst technology, and in particular to a method for preparing an inner wall surface-loaded honeycomb SCR denitration catalyst. Background Art

[0002] Existing honeycomb SCR denitration catalysts usually adopt a homogeneous integral extrusion process, and the common process steps are: mixing → kneading / mixing → screening → aging → extrusion molding → drying → secondary drying → calcination → sawing → packaging. The characteristic of this process is that the process is relatively simple, the active substance and the carrier raw material are mixed in advance, and produced in one go. However, this process has the following problems: as the amount of active components increases, the difficulty of product extrusion increases, the production efficiency decreases, it is not easy to extrude products with thinner wall thickness, and the production qualification rate decreases, resulting in increased production costs. In addition, while catalyzing denitration, the active components of the SCR denitration catalyst will also catalytically oxidize SO2 in the flue gas to generate SO3. In order to pursue higher denitration performance and increase the amount of active substances, the SO2 oxidation rate will increase significantly, which will cause the risk of catalyst ammonium sulfate poisoning and catalyst downstream related equipment blockage to increase sharply.

[0003] Another production process of honeycomb SCR denitrification catalyst is the carrier impregnation process. The common process steps are: mixing → kneading / mixing → screening → aging → extrusion molding → primary drying → secondary drying → calcination → sawing → active material impregnation → tertiary drying → secondary calcination → packaging. The advantages of this process are: the production efficiency and qualified rate of carriers that do not contain (or have very low content) active components are high, and it is also easier to produce small pores and thin-walled products. However, there are also the following problems: an additional calcination process is required, which will increase additional calcination equipment and calcination costs; since the solution loading mass percentage of the carrier can reach 25-30%, the qualified rate and physical properties (for example: compressive resistance) of the catalyst are easily reduced during the impregnation and calcination process.

[0004] In addition, there is also a carrier coating process for producing honeycomb SCR denitration catalysts, which prepares a relatively viscous active component slurry and directly coats it on the surface of the inner wall of the honeycomb carrier channel. The advantage of this process is that the process is relatively mature, but the disadvantage is that the cost of the process raw materials is high, the commonly used carrier "cordierite" is expensive, and the coating layer has a greater risk of peeling off. Summary of the invention

[0005] The purpose of the present application is to provide a method for preparing an inner wall surface loaded honeycomb SCR denitrification catalyst, wherein the catalyst product carrier part does not contain active substances, has high production efficiency and high product qualification rate; no additional calcination process is required; the active components are loaded on the inner wall surface of the honeycomb pores of the honeycomb carrier in an impregnated manner, which can effectively reduce the overall dosage of the active components, while reducing the occurrence of SO2 oxidation side reactions, avoiding secondary pollution and equipment blockage, etc., which helps to save production costs, improve production efficiency, and enhance product performance quality.

[0006] The technical solution of this application is as follows:

[0007] The present application provides a method for preparing an inner wall surface supported honeycomb SCR denitration catalyst, which comprises the following steps:

[0008] Carrier preparation: preparing carrier raw materials, mixing and kneading them, and then extruding them into a honeycomb structure, and drying them to obtain a honeycomb carrier, wherein the honeycomb carrier has a plurality of honeycomb channels;

[0009] Loading: preparing an active component solution, and spraying the active component solution into the plurality of honeycomb channels using an atomizing loading device; wherein the atomizing loading device comprises a nozzle, and the nozzle cooperates with the honeycomb channels; the nozzle is used to spray the active component solution into the honeycomb channels, so that the active component penetrates and is loaded on the surface layer of the inner wall of the honeycomb channels;

[0010] Drying and calcination: The honeycomb carrier loaded with active components is dried and then calcined to obtain a finished catalyst.

[0011] The embodiment of the present application also provides an inner wall surface supported honeycomb SCR denitration catalyst, which is prepared by the above-mentioned preparation method.

[0012] Compared with the prior art, the embodiments of the present application have at least the following advantages or beneficial effects:

[0013] In view of the above aspects, an embodiment of the present application provides a method for preparing an inner wall surface loaded honeycomb SCR deNOx catalyst, which loads the active components onto the honeycomb carrier by atomization spraying and infiltration, so that the active components penetrate into the inner wall surface of the carrier honeycomb pores, and by adjusting the atomization spraying amount and the concentration of the active component solution, and cooperating with the subsequent drying and calcination process, the active components are basically fully loaded on the inner wall surface of the honeycomb pores; while deeper in the inner wall, that is, deep in the solid part of the honeycomb carrier, no active components will be loaded or only a small amount of active components will exist. Since the SO2 oxidation reaction is a slow reaction (usually SO2 / SO3 < 5%), it will occur in the entire catalyst body phase; and in the present application scheme, the active components of the catalyst are loaded on the surface layer, and the solid interior of the carrier does not contain or contains very little active components; therefore, the active components loaded on the surface layer can fully carry out a faster denitration reaction, so that the active components loaded on the surface layer can quickly play their role, and the inner layer does not contain or contains only a small amount of active components, so that the slow SO2 oxidation side reaction can be effectively reduced, which can not only ensure a good denitration effect, but also greatly reduce the SO2 / SO3 conversion rate, thereby avoiding secondary pollution, catalyst poisoning due to sulfur, and equipment blockage, etc., which helps to extend the life of the equipment and product catalyst. At the same time, only loading all or most of the active components on the surface of the honeycomb channel wall can effectively reduce the amount of active components used, and incidentally reduce the amount of active substance co-solvent used, which will correspondingly reduce the safety risk of combustion in the subsequent drying process, help reduce raw material costs, improve production efficiency and production safety, and ensure product quality.

[0014] In addition, the preparation process provided in the present application uses an atomization loading device in combination with spraying to directly spray the active component solution on the inside of the carrier honeycomb pores. Compared with the conventional impregnation process, the atomization process of the present application is combined with subsequent rapid drying, and there is no need for secondary calcination, which can further improve production efficiency, make product quality more stable, and be more conducive to production.

[0015] Furthermore, in some embodiments of the present application, the above-mentioned carrier raw materials include nano titanium dioxide powder, alkali-free glass fiber, polyethylene oxide, methyl hydroxypropyl cellulose, ammonia water, and deionized water.

[0016] Further, in some embodiments of the present application, in the above-mentioned loading step, the number of the above-mentioned nozzles is multiple;

[0017] The size of a single nozzle corresponds to the size of a single honeycomb channel;

[0018] Alternatively, the size of a single nozzle corresponds to the total size of a plurality of adjacent honeycomb channels.

[0019] In the above embodiments, different types of nozzles can be used in combination to perform load operations according to the different size specifications of the honeycomb carrier and its honeycomb pores; for example, a single nozzle can be matched with a single honeycomb pore to perform a one-to-one spray load operation; for smaller-sized carriers and honeycomb pores, it can be considered to use a larger single nozzle to spray multiple honeycomb pores at the same time.

[0020] Further, in some embodiments of the present application, in the loading step, the nozzle is inserted into the honeycomb channel to spray the active component solution on the inner wall surface of the honeycomb channel;

[0021] Alternatively, the nozzle is close to the inlet side of the honeycomb channel, and directly sprays the active component solution into the honeycomb channel.

[0022] In the above embodiments, different spray loading modes may be selected according to actual needs, size specifications of the honeycomb carrier and the honeycomb pores, and product design.

[0023] Furthermore, in some embodiments of the present application, in the above-mentioned carrier preparation step, the prepared honeycomb carrier is provided with a plurality of load areas.

[0024] Furthermore, in some embodiments of the present application, the plurality of load areas are distributed along a horizontal direction of a cross section of the honeycomb carrier and / or a length direction of the honeycomb carrier.

[0025] Furthermore, in some embodiments of the present application, in the loading step, the nozzle is used to spray active component solutions of the same or different compositions into the honeycomb pores in different loading areas.

[0026] In the above embodiments, different types of active components can be sprayed into the loading area according to the different functions required by the product catalyst design; by spraying different active component materials in different loading areas, the product catalyst can be loaded with multiple active components at the same time, and the multiple active component materials are loaded on different blocks, thereby achieving the effect of a single product playing multiple catalytic production roles at the same time.

[0027] Furthermore, in some embodiments of the present application, in the above-mentioned drying and calcining step, the honeycomb carrier loaded with active components is dried by high-temperature hot air drying or microwave drying.

[0028] Furthermore, in some embodiments of the present application, in the above-mentioned carrier preparation step, the honeycomb structure is formed by kneading and extruding, and then primary drying and secondary drying are performed in sequence, and after secondary drying, the honeycomb carrier is directly sawed to obtain.

[0029] In the above embodiment, the process can directly carry out sawing to obtain the finished carrier after secondary drying without the need for additional calcination steps. The process flow is optimized to improve production efficiency and reduce production costs.

[0030] Further, in some embodiments of the present application, in the above-mentioned loading step, the prepared active component solution contains one or more active substances;

[0031] When the active component solution contains multiple active substances, if the multiple active substances (precursor solutions) are miscible with each other, they can be configured as a mixed solution and sprayed simultaneously;

[0032] If there are problems such as co-precipitation or immiscibility between multiple active substances (precursor solutions), the multiple active substance solutions can be sprayed separately in sequence; at this time, after one active substance solution has been sprayed, a rapid drying process is required before spraying the next active substance solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 This is a schematic diagram of the preparation process of the embodiment of the present application;

[0035] Figure 2 This is a schematic diagram of the cross-sectional structure of a honeycomb carrier in an embodiment of the present application;

[0036] Figure 3 This is a schematic diagram of the load area distribution along the horizontal direction of the cross section of the honeycomb carrier in the embodiment of the present application;

[0037] Figure 4 Schematic diagram of the load area distribution along the length direction of the honeycomb carrier in the embodiment of the present application.

[0038] Figure numerals: 1-honeycomb channel, 2-channel wall, 3-hollow channel, 4-surface layer, 5-inner surface layer, 6-inner layer. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0040] In the description of the embodiments of the present application, it should be noted that if the terms "horizontal", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is usually placed when used. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0041] In the description of the embodiments of the present application, "plurality" means at least 2.

[0042] It should be noted that the term "include" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "include..." do not exclude the existence of other identical elements in the process, method, article or device including its elements.

[0043] At the same time, the embodiments in this application and the features in the embodiments may be combined with each other without conflict.

[0044] The features and performance of the present application are further described in detail below in conjunction with the embodiments.

[0045] Example 1

[0046] This embodiment provides an inner wall surface supported honeycomb SCR denitration catalyst;

[0047] like Figure 2 to Figure 4 As shown, it includes a honeycomb carrier, the honeycomb carrier is provided with a plurality of honeycomb channels 1, any of the honeycomb channels 1 includes a channel wall 2 and a hollow channel 3; any of the channel walls 2 is provided with a surface layer 4 and an inner layer 6, the surface layer 4 is provided on the surface of the channel wall 2 and exposed to the hollow interior of the hollow channel 3, and the inner layer 6 is located in the solid interior of the channel wall 2;

[0048] The active components of the catalyst are loaded on the surface layer 4;

[0049] Alternatively, the active components of the catalyst are simultaneously loaded on the surface layer 4 and the inner layer 6 , and the concentration of the active components loaded on the surface layer 4 is greater than the concentration of the active components loaded on the inner layer 6 .

[0050] Furthermore, the thickness of the surface layer 4 is 10 to 500 μm.

[0051] Furthermore, an inner surface layer 5 is further provided on a side of the surface layer 4 close to the inner layer 6 , and the inner surface layer 5 is located between the inner layer 6 and the surface layer 4 ; the inner surface layer 5 is also loaded with active components.

[0052] Furthermore, the inner surface layer 5 and the surface layer 4 are loaded with the same or several active components;

[0053] Alternatively, the inner layer 5 and the surface layer 4 are loaded with different active components.

[0054] like Figure 3-4 As shown, further, the honeycomb carrier is provided with a plurality of loading areas, and different loading areas are loaded with the same or different active components.

[0055] Furthermore, the plurality of load areas are arranged along the horizontal direction of the cross section of the honeycomb carrier (eg Figure 3 As shown, the entire rectangular pattern is a cross section of a honeycomb carrier, wherein the multiple squares represent honeycomb channels 1, and different color blocks represent different load areas) and / or the length direction of the honeycomb carrier (such as Figure 4 As shown, the entire strip structure pattern is a honeycomb carrier, and different color blocks represent different load areas) distribution.

[0056] Furthermore, the active components of the catalyst are loaded on the honeycomb carrier in a permeation manner.

[0057] Furthermore, the active component of the above catalyst is any one or more of a vanadium-containing precursor, a tungsten-containing precursor, and a transition metal oxide.

[0058] Example 2

[0059] The present application embodiment provides an inner wall surface supported honeycomb SCR denitration catalyst, the product catalyst structure of which is designed based on Example 1, and its general process flow is as follows: Figure 1 As shown; it is prepared by the following method:

[0060] Preparation of carrier: prepare carrier raw materials, and take 65% of nano titanium dioxide powder, 6% of alkali-free glass fiber, 1.2% of polyethylene oxide, 0.6% of methyl hydroxypropyl cellulose, 3.2% of ammonia water, and 24% of deionized water by mass percentage;

[0061] The above mixture is evenly kneaded, sieved, and then extruded into a honeycomb structure by an extruder. After primary and secondary drying, it is sawed to obtain a honeycomb carrier with a side length of 150mm×150mm, 16×16 holes, a wall thickness of 1.0mm, and a length of 1000mm.

[0062] Loading: According to the target that the vanadium content of the inner wall surface layer (the surface layer of the inner wall of the honeycomb channel) of the product catalyst is 3% and the tungsten content is 5%, a mixed solution of ammonium metavanadate and ammonium metatungstate is designed and prepared as an active component solution for standby use;

[0063] The prepared active component solution is loaded into the liquid storage tank of the atomization loading equipment, the pressure of the liquid storage tank is adjusted to 4.0MPa, the pressure of the atomization compressed air is adjusted to 6.0MPa, and the prepared active component solution is sprayed into the honeycomb channels of the honeycomb carrier at a flow rate of 4ml / s using a nozzle; the single-hole spraying time is 1s, the nozzle is facing the carrier channel entrance, and the inner surfaces of the inner walls of 16×16 channels are sprayed one by one to load the active components so that they penetrate and load the surface layer of the inner wall of the honeycomb channel;

[0064] Drying and calcining: The honeycomb carrier loaded with active components is quickly dried by microwave drying process: the microwave frequency is 2450MHz or 915MHz, 915MHz is selected in this embodiment, the microwave power is 45KW, the residence time in the microwave resonance cavity is 90s, and the cavity is ventilated;

[0065] After rapid drying, calcination is performed to obtain the product catalyst.

[0066] Example 3

[0067] This embodiment is based on Embodiment 2, and differs from Embodiment 2 in that:

[0068] In the carrier preparation step, the dimensions of the prepared product honeycomb carrier are: side length 151mm×151mm, 12×12 holes, inner wall thickness 1.25mm, and length 1200mm.

[0069] In the loading step: an additional active component solution is prepared, specifically, a mixed solution of ammonium metavanadate and ammonium heptamolybdate is prepared according to the target of 3% vanadium content and 5% molybdenum content of the inner wall surface layer (the surface layer of the inner wall of the honeycomb channel) of the product catalyst; the active component solution in the original embodiment 2 is recorded as active component solution A, and the additional active component solution prepared in this embodiment is recorded as active component solution B;

[0070] In the loading step, 2×6 nozzle groups are prepared for the atomization loading equipment. The nozzles are equipped with 750mm long extension rods. The nozzles have a ring spray function. Before spraying, the nozzle extension rods are inserted into the carrier honeycomb channel 700mm through the motion mechanism. The pressure of the solution storage tank is adjusted to 3.0MPa, and the atomization compressed air pressure is adjusted to 5.0MPa. During the spraying of the active substance solution, the nozzles are gradually withdrawn from the inside of the channel at a speed of 0.7m / s. Through 12 reciprocating actions, Figure 4 The 12×12 honeycomb channels at the end of the carrier A are sprayed with active component solution A;

[0071] Using the same method, set the spray depth of the nozzle extension rod in the channel to 500mm. Figure 4 The honeycomb channels at the end of the carrier B are sprayed with the active component solution B; the remaining operations and steps are the same as those in Example 2.

[0072] Example 4

[0073] This embodiment is based on Embodiment 2, and differs from Embodiment 2 in that:

[0074] In the carrier preparation step, the size specifications of the prepared product honeycomb carrier are: a honeycomb carrier with a side length of 151 mm×151 mm, 45×45 holes, an inner wall thickness of 0.52 mm, and a length of 400 mm;

[0075] In the loading step, 9 wide-width atomizing nozzles are prepared for the atomizing loading device, arranged in a 3×3 manner, and placed in front of the entrance of the carrier honeycomb channel; a single nozzle can spray about 15×15 honeycomb channels at the same time, and the spraying operation of 45×45 channels can be completed at one time without moving the nozzle; the remaining operations and steps are the same as Example 2.

[0076] Example 5

[0077] This embodiment is based on Embodiment 2, and differs from Embodiment 2 in that:

[0078] In the loading step, the amount of active component solution used for spraying loading into the carrier honeycomb channels is tripled.

[0079] Example 6

[0080] This embodiment is based on Embodiment 2, and differs from Embodiment 2 in that:

[0081] In the loading step, when preparing the mixed solution of ammonium metavanadate and ammonium metatungstate, the concentration of the ammonium metavanadate solution used is reduced by 50%.

[0082] Comparative Example 1

[0083] This comparative example provides a conventional homogeneous honeycomb SCR denitration catalyst, and its preparation method is as follows:

[0084] The target vanadium content of the product catalyst is 3% and the tungsten content is 5%;

[0085] The raw materials are taken in percentage by mass: 65% of nano titanium dioxide powder, 6% of alkali-free glass fiber, 1.2% of polyethylene oxide, 0.6% of methyl hydroxypropyl cellulose, 2.7% of ammonia water, 8.5% of ammonium metavanadate solution, 6% of ammonium metatungstate solution, and 10% of water; they are mixed evenly, kneaded and formed into a honeycomb structure by an extruder, and after drying, calcining and sawing, a homogeneous honeycomb SCR denitration catalyst with a side length of 150mm×150mm, 16×16 holes, a wall thickness of 1.0mm, and a length of 1000mm is made.

[0086] Comparative Example 2

[0087] This comparative example provides an impregnated honeycomb SCR denitration catalyst, the preparation process of which is basically the same as that of Example 2, except that the loading step is that this comparative example uses an impregnation process to load the active component instead of the atomization spray loading in Example 2;

[0088] Specifically:

[0089] The target vanadium content of the product catalyst is 3% and the tungsten content is 5%;

[0090] In the carrier preparation step, after primary drying and secondary drying, calcination is performed again, and then sawing is performed to obtain a carrier with a side length of 150 mm×150 mm, 16×16 holes, a wall thickness of 1.0 mm, and a length of 1000 mm;

[0091] In the loading step, a nozzle is not used for spray loading. Instead, the carrier is vertically immersed in an excess volume of active component solution so that the liquid level exceeds the upper surface of the carrier by more than 100 mm for 30 minutes, during which time the mixed solution is ensured to flow up and down; then, after three consecutive drying box calcinations, the product impregnated catalyst is obtained.

[0092] Test Example 1

[0093] Process test:

[0094] The relevant data of each production process in Examples 2 to 6 and Comparative Examples 1 to 3 were statistically analyzed, and the specific items and results are shown in Table 1:

[0095] Table 1

[0096]

[0097]

[0098] It can be seen from the results that the catalyst extrusion efficiency of the product provided in the embodiment of the present application is higher than that of the traditional homogeneous catalyst (Comparative Example 1), and the qualified rate of process products is generally higher.

[0099] Compared with the impregnated catalyst product (Comparative Example 2), the product of the embodiment of the present application has similar carrier extrusion efficiency, while the qualified rate of the process product of the embodiment of the present application is slightly higher than that of the comparative example 2.

[0100] Test Example 2

[0101] Product testing:

[0102] The active substance content of the carrier part of the catalyst of this embodiment and the comparative example was tested:

[0103] Test of active substance content on the carrier surface: The carrier portion of each group of product catalysts was cut and sampled to obtain circular sheet samples with a diameter of about 5 cm. The cross-sections were polished, taking care not to wear the surface. The active substance content of the samples was tested using a wavelength dispersive XRF instrument. The results are shown in Table 2.

[0104] Test of average active substance content of carrier: The catalyst carrier of each group of products was sampled and ground into powder and pressed into tablets, and then the active substance content was tested using a wavelength dispersive XRF instrument. The results are shown in Table 2.

[0105] Table 2

[0106]

[0107]

[0108] The active substance content of the catalyst product of this embodiment and the comparative example was tested:

[0109] Test of the content of active substances on the catalyst surface (inner wall surface of honeycomb channels): Cut each group of catalyst products, take a circular sheet with a diameter of about 5 cm as a complete inner wall as a sample, and grind the cross-section, taking care not to wear the inner wall surface area, and use a wavelength dispersive XRF instrument to quantitatively detect the active substances. The results are shown in Table 3;

[0110] Catalyst average active substance content test: Take samples of each group of catalyst products, grind them into powder, press them into tablets, and then use wavelength dispersive XRF instrument to test the active substance content. The results are shown in Table 3:

[0111] Table 3

[0112]

[0113] In the table, Example 3-A refers to the data in this column, which is the content data of the active component loaded on the carrier A end (active component solution A) in the product catalyst of Example 3; Example 3-B refers to the data in this column, which is the content data of the active component loaded on the carrier B end (active component solution B) in the product catalyst of Example 3.

[0114] Catalytic performance test of product catalyst:

[0115] The catalysts of Example 2 and Comparative Examples 1-2 were cut to obtain samples with 2×2 holes and a length of 260 mm. The denitration performance and SO2 / SO3 conversion rate were tested under the flue gas conditions shown in Table 4 (NH3 was not added when testing the SO2 / SO3 conversion rate). The results are shown in Table 5:

[0116] Table 4

[0117] Flue gas parameters unit Target value <![CDATA[O2 content]]> vol.%,dry 2 <![CDATA[H2O content]]> vol.%,wet 10 NO content vpm,STPdry 480 <![CDATA[NH3 content]]> vpm,STPdry 480 <![CDATA[SO2 content]]> vpm,STPdry 480 Total flue gas volume L / h,dry 918 temperature ℃ 380

[0118] Table 5

[0119]

[0120] From the above results, we can see that:

[0121] The carrier part of the catalyst of the product of the embodiment of the present application does not contain active substances (see Table 2). Combined with the results in Table 1, it can be seen that the process efficiency and product qualification rate of the product of the embodiment are significantly better than those of the traditional homogeneous catalyst (Comparative Example 1).

[0122] The content of active substances on the inner wall surface of the catalyst samples of Examples 2 to 6 is much higher than their average active substance content (see Table 3), and the average active component content of the products of the examples of the present application is significantly lower than that of the homogeneous catalyst (Comparative Example 1) and the impregnated catalyst (Comparative Example 2); This shows that the embodiments of the present application can achieve a high load on the inner wall surface of the pores, containing more active substances, while the solid interior of the carrier contains no or only a very small amount of active substances; and when the content of surface active substances is at the same level, the average active component usage of the process of this embodiment is significantly lower than that of Comparative Examples 1 and 2.

[0123] As can be seen from Table 3, Examples 2 to 4 respectively adopted three different nozzle configurations and spray loading methods, and achieved good loading effects of active substances on the inner wall surface for honeycomb SCR catalyst carriers with different pore sizes.

[0124] As can be seen from Table 5, compared with Comparative Examples 1 and 2, although the amount of active material used in Example 2 is greatly reduced, the denitration performance is basically the same, and the side reaction SO2 / SO3 conversion rate is lower, indicating that the product of Example 2 can achieve better catalytic performance.

[0125] Compared with Example 5, the spray loading amount of active substance in Example 2 was tripled, which did not significantly increase the content of active substance on the catalyst surface (see Table 3). However, the average active substance content of the catalyst in Example 5 was significantly increased. Combined with Table 2, the carrier part contained almost no active substance, indicating that changing the spraying amount of active substance can change the loading depth of the active substance on the inner wall surface of the catalyst carrier pore.

[0126] Compared with Example 6, the concentration of ammonium metavanadate solution used in the active component solution of Example 2 is reduced by 50%, and the content of active substances on the catalyst surface (see Table 3) is significantly reduced. The average active substance content of the catalyst is also reduced, indicating that the change in the concentration of the active component solution used can affect its loading effect.

[0127] In the scheme of Example 3, the carrier is provided with two ends A and B, and the active component solution A and the active component solution B are sprayed and loaded respectively; as can be seen from Table 3, the active substances vanadium and tungsten are loaded on the catalyst A end, and the active substances vanadium and molybdenum are loaded on the catalyst B end, which indicates that the preparation method of the present invention achieves the effect of partitioning and loading different types of active components on the catalyst carrier.

[0128] In summary, the embodiments of the present application provide a method for preparing an inner wall surface loaded honeycomb SCR deNOx catalyst, which loads the active components onto the honeycomb carrier by atomization spraying and infiltration, so that the active components penetrate into the inner wall surface of the carrier honeycomb pores, and adjust the atomization spraying amount and the concentration of the active component solution, in conjunction with the subsequent drying and calcining process, so that the active components are basically fully loaded on the inner wall surface of the honeycomb pores; while deeper in the inner wall, that is, deep in the solid part of the honeycomb carrier, no active components will be loaded or only a small amount of active components will exist. Since the SO2 oxidation reaction is a slow reaction (usually SO2 / SO3 < 5%), it will occur in the entire catalyst body phase; and in the present application scheme, the active components of the catalyst are loaded on the surface layer, and the solid interior of the carrier does not contain or contains very little active components; therefore, the active components loaded on the surface layer will first undergo a faster denitration reaction, so that the active components loaded on the surface layer can quickly play their role, while the inner layer does not contain or contains only a small amount of active components, so that the occurrence of the slower SO2 oxidation side reaction can be effectively reduced, which can not only ensure a good denitration effect, but also greatly reduce the SO2 / SO3 conversion rate, thereby avoiding secondary pollution, catalyst poisoning due to sulfur, and equipment blockage, etc., which helps to extend the life of the equipment and product catalyst. At the same time, only loading all or most of the active components on the surface of the honeycomb channel wall can effectively reduce the amount of active components used, and incidentally reduce the amount of active substance co-solvent used, which will correspondingly reduce the safety risk of combustion in the subsequent drying process, help reduce raw material costs, improve production efficiency and production safety, and ensure product quality. In addition, the preparation process provided in the present application uses an atomization loading device in combination with spraying to directly spray the active component solution on the inside of the carrier honeycomb pores. Compared with the conventional impregnation process, the atomization process of the present application is combined with subsequent rapid drying, and there is no need for secondary calcination, which can further improve production efficiency, make product quality more stable, and be more conducive to production.

[0129] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

Claims

1. A method for preparing an inner wall surface supported honeycomb SCR denitration catalyst, characterized in that: It includes the following steps: Carrier preparation: preparing carrier raw materials, mixing and kneading them, and then extruding them into a honeycomb structure, and drying them to obtain a honeycomb carrier having a plurality of honeycomb channels; Loading: preparing an active component solution, and spraying the active component solution into the plurality of honeycomb channels using an atomizing loading device; wherein the atomizing loading device comprises a nozzle, and the nozzle cooperates with the honeycomb channels; the nozzle is used to spray the active component solution into the honeycomb channels, so that the active component penetrates and is loaded on the surface layer of the inner wall of the honeycomb channels; Drying and calcining: The honeycomb carrier loaded with active components is quickly dried and then calcined to obtain a finished catalyst.

2. The method for preparing the inner wall surface supported honeycomb SCR denitration catalyst according to claim 1, characterized in that: The carrier raw materials include nano titanium dioxide powder, alkali-free glass fiber, polyethylene oxide, methyl hydroxypropyl cellulose, ammonia water, and deionized water.

3. The method for preparing the inner wall surface supported honeycomb SCR denitration catalyst according to claim 1, characterized in that: In the loading step, the number of the nozzles is multiple; The size of a single nozzle corresponds to the size of a single honeycomb channel; Alternatively, the size of a single nozzle corresponds to the total size of a plurality of adjacent honeycomb channels.

4. The method for preparing an inner wall surface supported honeycomb SCR denitration catalyst according to claim 1, characterized in that: In the loading step, the nozzle is inserted into the interior of the honeycomb channel to spray the active component solution on the inner wall surface of the honeycomb channel; Alternatively, the nozzle is close to the inlet side of the honeycomb channel, and directly sprays the active component solution into the honeycomb channel.

5. The method for preparing an inner wall surface supported honeycomb SCR denitration catalyst according to claim 1, characterized in that: In the carrier preparation step, the prepared honeycomb carrier is provided with a plurality of loading areas.

6. The method for preparing an inner wall surface supported honeycomb SCR denitration catalyst according to claim 5, characterized in that: The plurality of load areas are distributed along the horizontal direction of the cross section of the honeycomb carrier and / or the length direction of the honeycomb carrier.

7. The method for preparing an inner wall surface supported honeycomb SCR denitration catalyst according to claim 5, characterized in that: In the loading step, the nozzle is used to spray active component solutions of the same or different components into the honeycomb channels in different loading areas.

8. The method for preparing an inner wall surface supported honeycomb SCR denitration catalyst according to claim 1, characterized in that: In the drying and calcining step, the honeycomb carrier loaded with active components is quickly dried by high-temperature hot air drying or microwave drying.

9. The method for preparing an inner wall surface supported honeycomb SCR denitration catalyst according to claim 1, characterized in that: In the carrier preparation step, the honeycomb structure is formed by kneading and extruding, and then primary drying and secondary drying are performed in sequence. After the secondary drying, the honeycomb carrier is directly sawed to obtain the honeycomb carrier.

10. An inner wall surface supported honeycomb SCR denitration catalyst, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 9.

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