A catalyst for reducing nitrogen oxides in flue gas and its preparation and treatment methods

Abstract

This invention provides a flue gas nitrogen oxide reduction catalyst and its preparation and processing methods, relating to the field of industrial catalysis technology. The flue gas nitrogen oxide reduction catalyst has two functional zones, A and B, arranged sequentially along the flue gas flow direction. Functional zone A is a porous structure located at the inlet end for intercepting dust in the flue gas; functional zone B is located downstream of functional zone A and is the main reaction zone for the catalytic reduction of nitrogen oxides. The flue gas nitrogen oxide reduction catalyst provided by this invention protects the catalytic activity of functional zone B by intercepting dust in functional zone A. This partitioned design synergistically solves the problems of clogging and poisoning, significantly extending the catalyst's lifespan.

Description

Technical Field

[0001] This invention relates to the field of industrial catalysis technology, and more specifically, to a flue gas nitrogen oxide reduction catalyst and its preparation and processing methods. Background Technology

[0002] The rapid development of industrial production has led to the production of nitrogen oxides (NOx). x Emissions of air pollutants such as nitrogen oxides (NOx) continue to increase. NOx is one of the main precursors to photochemical smog and acid rain, posing a potential threat to the ecological environment and human health. Therefore, effective control of NOx in industrial flue gas has become an important issue in environmental protection. Among numerous flue gas denitrification technologies, selective catalytic reduction (SCR) technology is widely recognized as the most mainstream and effective approach due to its high denitrification efficiency, lack of secondary pollution, and mature technology. The core of this technology lies in the catalyst, which can selectively reduce NOx in flue gas to harmless nitrogen and water within a specific temperature window in the presence of a reducing agent (usually ammonia).

[0003] In existing industrial practices, especially in key sectors such as petrochemicals, SCR technology has been widely applied. For example, ethylene cracking furnaces, as core equipment in petrochemical processes, generate large amounts of flue gas containing nitrogen oxides during combustion. Currently, corrugated plate or honeycomb catalysts, using titanium dioxide as a carrier and loaded with active components such as vanadium pentoxide and tungsten trioxide, are commonly used to treat this flue gas. These catalysts exhibit good catalytic activity and stability under normal operating conditions and are one of the standard technical solutions for treating nitrogen oxides from stationary sources. By installing the catalyst module at an appropriate location in the convection section of the cracking furnace, the flue gas undergoes a reduction reaction on the catalyst surface, thereby controlling nitrogen oxide emissions.

[0004] However, directly applying traditional vanadium-titanium-based SCR catalysts to the complex flue gas environment of ethylene cracking furnaces exposes numerous technical drawbacks. The flue gas composition of ethylene cracking furnaces is extremely complex, containing not only conventional components but also heavy metal dust such as chromium and nickel generated from upstream processes or equipment pipelines. These micron-sized solid particles impact and deposit on the windward side of the catalyst with the high-speed flow of flue gas, gradually clogging the catalyst's micropore channels. This physical blockage not only significantly increases the operating pressure difference of the flue gas flowing through the catalyst bed, increasing system energy consumption, but can also lead to furnace pressure fluctuations in severe cases, affecting the stable operation of the entire cracking unit. Furthermore, these heavy metal components may chemically react with the active sites of the catalyst, causing catalyst poisoning and irreversibly reducing its catalytic activity.

[0005] Besides physical blockage and chemical poisoning, the wide temperature range during ethylene cracking furnace operation poses a severe challenge to catalyst durability. The unit experiences drastic temperature fluctuations during start-up, shutdown, and load adjustments. Prolonged exposure to high temperatures accelerates the phase transformation and grain growth of the catalyst support (such as anatase titanium dioxide), leading to thermal sintering. Sintering causes a sharp decrease in the catalyst's specific surface area and a significant loss of active sites, resulting in permanent high-temperature deactivation. In summary, existing catalysts used in ethylene cracking furnaces face multiple problems in practical applications, including blockage and poisoning caused by heavy metal dust, and high-temperature sintering deactivation due to wide-range operation. These problems combined significantly shorten the effective lifespan of the catalyst, increase the frequency and cost of replacement and maintenance, and fail to meet the urgent needs of modern chemical plants for long-term, high-efficiency, and low-cost operation.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a flue gas nitrogen oxide reduction catalyst and its preparation and treatment methods. The flue gas nitrogen oxide reduction catalyst synergistically solves the two major problems of catalyst blockage and poisoning, thereby significantly extending its service life and operational stability in high dust flue gas environments.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0009] In a first aspect, the present invention provides a flue gas nitrogen oxide reduction catalyst, wherein functional regions A and B are sequentially arranged along the flue gas flow direction;

[0010] Functional area A is located at the inlet end of the flue gas nitrogen oxide reduction catalyst and is a porous structure used to intercept dust in the flue gas; the dust includes heavy metals and / or carbon black;

[0011] The B functional region is located downstream of the A functional region and is the main reaction region for the catalytic reduction of nitrogen oxides.

[0012] In optional embodiments, the flue gas nitrogen oxide reduction catalyst is an integral structure composed of functional regions A and B; or, the flue gas nitrogen oxide reduction catalyst is a split structure composed of two separate catalysts, functional regions A and B, which are separable and can be longitudinally spliced ​​together along the flue gas flow direction; and / or, the shape of the flue gas nitrogen oxide reduction catalyst is corrugated plate, honeycomb, or flat plate; and / or, the height of functional region A accounts for 5% to 40% of the longitudinal height of the flue gas nitrogen oxide reduction catalyst; and / or, the height of functional region B accounts for 60% to 95% of the longitudinal height of the flue gas nitrogen oxide reduction catalyst; and / or, the average pore size range of functional region A is 2 μm to 50 μm; and / or, the specific surface area of ​​functional region A is greater than 200 m². 2 / g; and / or, the average pore size of the B functional region ranges from 2nm to 20nm; and / or, the specific surface area of ​​the B functional region is greater than 70m². 2 / g, thereby forming catalyst products covering millimeter-micrometer-nanopore structures.

[0013] In an optional embodiment, the A functional region is composed of a first framework, a first support, and a first catalytic component;

[0014] Wherein, the first skeleton includes at least one of glass fiber paper, glass fiber mat and metal wire mesh; and / or, the first support is γ-alumina; and / or, the first catalytic component includes magnesium oxide, cerium oxide and aluminum oxide.

[0015] In an optional embodiment, in the first catalytic component of the functional region A, the mass percentage of magnesium oxide is 5% to 10%, the mass percentage of cerium oxide is 3% to 5%, and the mass percentage of aluminum oxide is 4% to 9%.

[0016] In an optional implementation, a pore control agent is also added to functional region A;

[0017] The pore control agent includes at least one of guar gum powder, rice husk powder, starch, graphite and cellulose; and / or the addition ratio of the pore control agent is 1% to 4%.

[0018] In an optional embodiment, the B functional region is composed of a second framework, a second support, and a second catalytic component;

[0019] Wherein, the second skeleton includes at least one of glass fiber paper, glass fiber mat, and metal wire mesh; and / or, the second support is a mixture of titanium dioxide and zirconium oxide; and / or, the second catalytic component includes vanadium pentoxide, tungsten trioxide, molybdenum trioxide, and niobium pentoxide.

[0020] In an optional embodiment, the mass percentage of zirconium oxide in the second carrier of the B functional region is 4% to 18%; and / or, the mass percentage of vanadium pentoxide in the second catalytic component of the B functional region is 1% to 9%, the mass percentage of tungsten trioxide is 5% to 15%, the mass percentage of molybdenum trioxide is 2% to 5%, and the mass percentage of niobium pentoxide is 0.2% to 2.5%.

[0021] In a second aspect, the present invention provides a method for preparing a flue gas nitrogen oxide reduction catalyst as described in any of the foregoing embodiments, wherein the flue gas nitrogen oxide reduction catalyst comprises an integral structure and a split structure;

[0022] When the flue gas nitrogen oxide reduction catalyst has a split structure, the preparation method of the flue gas nitrogen oxide reduction catalyst includes: preparing the framework materials of functional regions A and B into corresponding geometric shapes as finished frameworks; preparing support slurries for functional regions A and B, immersing the finished frameworks into the corresponding support slurries, and obtaining the supports corresponding to functional regions A and B through a first drying and a first calcination; immersing the supports into corresponding catalytic component solutions, and performing a second drying and a second calcination to obtain functional regions A and B; and / or,

[0023] When the flue gas nitrogen oxide reduction catalyst is an integral structure, the preparation method of the flue gas nitrogen oxide reduction catalyst includes: preparing an integral geometric shape based on the framework materials of functional regions A and B, as a finished framework; preparing support slurries for functional regions A and B respectively; immersing one end of functional region A of the finished framework into the corresponding support slurry for a first drying of one end of functional region A; then immersing one end of functional region B of the finished framework into the corresponding support slurry for a first drying of one end of functional region B; and finally performing a first calcination on the whole to obtain a support composed of functional regions A and B; immersing one end of functional region A of the support into a corresponding catalytic component solution for a second drying of one end of functional region A; then immersing one end of functional region B of the support into the corresponding catalytic component solution for a second drying of one end of functional region B; and finally performing a second calcination on the whole to obtain the flue gas nitrogen oxide reduction catalyst.

[0024] Thirdly, the present invention provides a method for preparing a flue gas nitrogen oxide reduction catalyst as described in the foregoing embodiments, wherein the drying temperature of the first drying is 90℃~120℃; and / or, the calcination temperature of the first calcination is 500℃~660℃; and / or, the drying temperature of the second drying is 90℃~120℃; and / or, the calcination temperature of the second calcination is 380℃~520℃; and / or, the solid content of the support slurry is 20%~55%; and / or, the viscosity of the support slurry is 400 mPa·s~1800 mPa·s; and / or, the solid content of the catalytic component solution is 3%~27%; and / or, the viscosity of the catalytic component solution is 5 mPa·s~70 mPa·s.

[0025] Fourthly, the present invention provides a method for treating nitrogen oxides in flue gas from an ethylene cracking furnace, comprising:

[0026] The flue gas to be treated is sequentially guided through the A and B functional regions of the flue gas nitrogen oxide reduction catalyst as described in any of the foregoing embodiments.

[0027] This invention provides a flue gas nitrogen oxide reduction catalyst and its preparation and processing methods. Compared with the prior art, this flue gas nitrogen oxide reduction catalyst divides the catalyst into two functional regions, A and B, along the flue gas flow direction, thereby achieving a specialized division of catalyst functions and producing significant beneficial effects.

[0028] Firstly, the A functional zone at the inlet, a porous structure specifically designed to intercept heavy metals, carbon black, and other dust particles, plays a crucial protective role. It actively captures and contains solid particles carried in the flue gas, preventing these particles from directly impacting and clogging the core reaction area of ​​the catalyst. This structural design directly alleviates the catalyst channel blockage problem caused by dust accumulation, allowing flue gas to pass through more smoothly, significantly reducing the operating pressure differential of the catalyst bed, and contributing to the stable operation of the entire process system.

[0029] Secondly, because functional zone A undertakes the tasks of physical interception and filtration and chemical inhibition at the front end, it creates a cleaner reaction environment for functional zone B downstream. The main reaction zone (functional zone B) is thus protected from the physical covering and chemical poisoning of heavy metal dust, and its active sites for catalytic reduction of nitrogen oxides are effectively protected. This allows functional zone B to maintain its inherent high catalytic activity for a longer period, thereby ensuring the continuous and efficient removal of nitrogen oxides from the entire catalyst system and achieving a higher overall conversion efficiency.

[0030] This integrated structure, where functional zones A and B work in tandem, effectively solves the problem of traditional single-structure catalysts easily experiencing both blockage and poisoning failure in complex flue gas environments. Because the catalyst is a single unit or tightly connected components, it also saves internal reactor space. By separating the "protection" and "main reaction" functions, this design not only improves catalyst performance but, more importantly, slows down the catalyst deactivation process, significantly extending its overall service life and enabling the equipment to achieve longer-term continuous and stable operation. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the integrated structure of the flue gas nitrogen oxide reduction catalyst in the embodiments of this application;

[0033] Figure 2 This is a schematic diagram of the split structure of the flue gas nitrogen oxide reduction catalyst in the embodiments of this application;

[0034] Figure 3 This is a scanning electron microscope image of the catalyst inlet after use in Example 1 of the test experiment in this application;

[0035] Figure 4 This is a scanning electron microscope image of the catalyst inlet after use in Comparative Example 1 of the test experiment in this application.

[0036] Figure label:

[0037] 100, Flue gas nitrogen oxide reduction catalyst; 1, Functional zone A; 2, Functional zone B. Detailed Implementation

[0038] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0039] In this embodiment of the application, a flue gas nitrogen oxide reduction catalyst is provided, wherein functional regions A and B are sequentially arranged along the flue gas flow direction.

[0040] Functional area A is located at the inlet end of the flue gas nitrogen oxide reduction catalyst and is a porous structure used to intercept dust in the flue gas; the dust includes heavy metals and / or carbon black;

[0041] The B functional region is located downstream of the A functional region and is the main reaction region for the catalytic reduction of nitrogen oxides.

[0042] Flue gas nitrogen oxide reduction catalysts are functional materials used in industrial processes. Their core function is to act as a medium, promoting and accelerating the reduction of nitrogen oxides (NOx) in flue gas without consuming themselves. x The chemical transformation of nitrogen oxides is the ultimate goal, aiming to convert harmful nitrogen oxides into harmless substances, thereby purifying flue gas. This substance is itself a physical product used in flue gas treatment equipment.

[0043] The catalyst product is structurally divided into two core components: functional zone A and functional zone B. These two parts are not randomly mixed, but are arranged sequentially along the direction of flue gas flow, following the order of "A first, then B".

[0044] (1) Functional area A: This is the inlet part of the catalyst, which is the area where the flue gas first comes into contact.

[0045] (2) B functional region: This is the downstream part of the catalyst, which follows the A functional region.

[0046] This structural division is the most fundamental characteristic of the substance, meaning that it is not a homogeneous whole, but a complex with internal structure and functional gradients.

[0047] The function of functional zone A is defined as "intercepting heavy metals and / or carbon black dust in flue gas." Its primary task is physical action, acting like a filter or sieve to specifically capture and contain solid particulate pollutants (such as heavy metals and carbon black dust) carried in flue gas. Its structure is "porous," a feature designed to achieve its interception function. Simultaneously, functional zone A is loaded with alkaline catalytic components such as magnesium oxide, cerium oxide, and aluminum oxide, enabling it to chemically capture SO3 and carbon black, and oxidize the captured carbon black.

[0048] The aforementioned functional zone B is the "main reaction zone for the catalytic reduction of nitrogen oxides." In other words, the core task of functional zone B is chemical reaction, and it is the main site in the entire catalyst product where the target chemical reaction (i.e., nitrogen oxide reduction) actually occurs.

[0049] The catalyst works by employing a "division of labor" or "two-stage treatment" approach. It breaks down the complex task of flue gas treatment into two consecutive steps, each completed by a dedicated functional area.

[0050] (1) Pretreatment stage: The flue gas first enters functional area A. Here, the "impurities" (heavy metals, carbon black and other dust) in the flue gas are physically and chemically intercepted and removed. The purpose of this step is to purify the flue gas and clear the way for subsequent chemical reactions.

[0051] (2) Core reaction stage: The relatively clean flue gas, after pretreatment in functional zone A, enters functional zone B. Here, the target pollutants (nitrogen oxides) in the flue gas undergo a chemical reaction with the reducing agent under the action of a catalyst and are transformed into harmless substances.

[0052] The core idea of ​​this principle is to protect the core reaction zone (B function zone) by setting up a "protected zone" (A function zone), preventing the core reaction zone from failing prematurely due to blockage or poisoning by impurities.

[0053] This structural design offers significant advantages and benefits. By intercepting dust in functional zone A, physical blockage and chemical poisoning of the main reaction zone (functional zone B) are effectively prevented, thus delaying the decline of catalyst activity and enabling it to operate for a longer period. Because functional zone B is well protected, its catalytic activity can be maintained at a high level for a long time, ensuring that the flue gas treatment system can continuously, stably, and efficiently remove nitrogen oxides. In other words, it prevents catalyst blockage, avoids the problem of increased system pressure differential caused by obstructed flue gas passages, and ensures the stable and safe operation of the entire production process.

[0054] In some embodiments, the flue gas nitrogen oxide reduction catalyst is an integral structure composed of functional regions A and B (see reference). Figure 1 Alternatively, the flue gas nitrogen oxide reduction catalyst is a split structure consisting of two separate catalysts, functional regions A and B, which can be longitudinally assembled along the flue gas flow direction (see reference). Figure 2 ).

[0055] The catalyst product is structurally divided into two core components: functional zone A and functional zone B. These two parts are not randomly mixed, but rather arranged sequentially along the flue gas flow direction, following a "A first, then B" order. Functional zone A is the catalyst inlet section, the area where the flue gas first comes into contact with the catalyst; functional zone B is the downstream section of the catalyst, immediately following functional zone A. This structural division is the most fundamental characteristic of the material, meaning it is not a homogeneous whole, but a complex with internal structure and functional gradients.

[0056] To achieve the above division of functional regions A and B, the catalyst can adopt two specific physical structures:

[0057] (1) Integrated structure: This refers to the fact that functional regions A and B are manufactured on a single, continuous catalyst matrix. These two functional regions are different parts of the same physical entity and cannot be separated from each other. For example, on the same framework, a single catalyst module with functional region A in the front half and functional region B in the back half can be prepared by impregnating different slurries in sections.

[0058] (2) Split structure: This refers to two physically independent catalyst modules, A and B. They are manufactured separately and installed together by splicing and combining during use. This structure allows the two functional areas to be handled separately. For example, when functional area A, which serves as a protective layer, fails due to intercepting a large amount of dust, only functional area A module can be replaced without replacing the still effective functional area B module. This brings convenience and economy to maintenance and replacement.

[0059] In some embodiments, the flue gas nitrogen oxide reduction catalyst is in the shape of a corrugated plate, honeycomb, or flat plate.

[0060] In some embodiments, the height of functional zone A accounts for 5% to 40% of the longitudinal height of the flue gas nitrogen oxide reduction catalyst. For example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc.

[0061] In some embodiments, the height of functional zone B accounts for 60% to 95% of the longitudinal height of the flue gas nitrogen oxide reduction catalyst. For example, it can be 60%, 70%, 80%, 90%, 95%, etc.

[0062] In some embodiments, the average pore size of functional region A ranges from 2 μm to 50 μm. For example, it can be 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, etc.

[0063] In some implementations, the specific surface area of ​​functional region A is greater than 200 m². 2 / g.

[0064] In some implementations, the average aperture of the B functional region ranges from 2 nm to 20 nm. For example, it can be 2 nm, 5 nm, 10 nm, 15 nm, 20 nm, etc.

[0065] In some implementations, the specific surface area of ​​functional region B is greater than 70 m². 2 / g.

[0066] In some embodiments, the functional region A is composed of a first framework, a first support, and a first catalytic component;

[0067] Wherein, the first skeleton includes at least one of glass fiber paper, glass fiber mat and metal wire mesh; and / or, the first support is γ-alumina; and / or, the first catalytic component includes magnesium oxide, cerium oxide and aluminum oxide.

[0068] In some embodiments, in the first catalytic component of the functional region A, the mass percentage of magnesium oxide is 5% to 10% (e.g., 5%, 6%, 7%, 8%, 9%, 10%, etc.), the mass percentage of cerium oxide is 3% to 5% (e.g., 3%, 4%, 5%, etc.), and the mass percentage of aluminum oxide is 4% to 9% (e.g., 4%, 5%, 6%, 7%, 8%, 9%, etc.).

[0069] In some embodiments, a pore control agent is also added to functional region A;

[0070] The pore control agent includes at least one of guar gum powder, rice husk powder, starch, graphite and cellulose; and / or the addition ratio of the pore control agent is 1% to 4% (e.g., 1%, 2%, 3%, 4% etc.).

[0071] In some embodiments, the B functional region is composed of a second framework, a second support, and a second catalytic component;

[0072] Wherein, the second skeleton includes at least one of glass fiber paper, glass fiber mat, and metal wire mesh; and / or, the second support is a mixture of titanium dioxide and zirconium oxide; and / or, the second catalytic component includes vanadium pentoxide, tungsten trioxide, molybdenum trioxide, and niobium pentoxide.

[0073] In some embodiments, the zirconium oxide content in the second carrier of the B functional region is 4% to 18% by mass; and / or,

[0074] In the second catalytic component of the B functional region, the mass percentage of vanadium pentoxide is 1% to 9% (e.g., it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, etc.), the mass percentage of tungsten trioxide is 5% to 15% (e.g., it can be 5%, 8%, 10%, 12%, 15%, etc.), the mass percentage of molybdenum trioxide is 2% to 5% (e.g., it can be 2%, 3%, 4%, 5%, etc.), and the mass percentage of niobium pentoxide is 0.2% to 2.5% (e.g., it can be 0.2%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, etc.).

[0075] In this application embodiment, a method for preparing a flue gas nitrogen oxide reduction catalyst as described in any of the foregoing embodiments is provided, wherein the flue gas nitrogen oxide reduction catalyst includes an integral structure and a split structure;

[0076] (1) When the flue gas nitrogen oxide reduction catalyst has a split structure, the preparation method of the flue gas nitrogen oxide reduction catalyst includes: preparing the framework materials of functional region A and functional region B into corresponding geometric shapes as finished frameworks; preparing the support slurries of functional region A and functional region B; immersing the finished framework into the corresponding support slurries; and obtaining the supports corresponding to functional region A and functional region B through a first drying and a first calcination; immersing the supports into the corresponding catalytic component solutions; and performing a second drying and a second calcination to obtain functional region A and functional region B respectively.

[0077] The above-described skeleton forming steps can use fiberglass paper, fiberglass mat, or wire mesh as the "skeleton material" and process it into the required geometric shape, such as a corrugated plate. Since it is a split-type fabrication, two independent skeleton products with potentially different sizes will be obtained: one for the subsequent fabrication of functional region A, and the other for the fabrication of functional region B.

[0078] Next, the support loading step is performed, which forms the substrate for the supported catalyst. First, two different "support slurries" are prepared according to the different requirements of functional regions A and B (e.g., γ-alumina slurry is used for region A, and titanium dioxide-zirconia slurry is used for region B). Then, the two independent finished frameworks are immersed in their corresponding slurries. After drying (e.g., 90~120℃) to remove moisture, they are then calcined at high temperature (e.g., 500~660℃) to firmly attach the support material to the framework, forming a stable porous structure. After completion, two independent semi-finished products coated with support layers are obtained.

[0079] Finally, the catalyst component loading step is performed, which is the last step in forming catalytic activity. Similarly, solutions containing the required "catalytic components" for functional regions A and B (such as magnesium oxide and cerium oxide in region A; vanadium pentoxide and tungsten trioxide in region B) are prepared separately. The two semi-finished support products obtained in the previous step are immersed in their corresponding solutions. Finally, they are dried again (e.g., 90~120℃) and calcined (e.g., 380~520℃) to uniformly disperse and fix the catalytically active components on the support. After completing this step, two final, independently usable catalyst modules are obtained: the A functional region module and the B functional region module.

[0080] (2) When the flue gas nitrogen oxide reduction catalyst is an integral structure, the preparation method of the flue gas nitrogen oxide reduction catalyst includes: preparing an integral geometric shape based on the framework materials of functional regions A and B as a finished framework; preparing support slurries for functional regions A and B respectively; immersing one end of functional region A of the finished framework into the corresponding support slurry and performing a first drying of one end of functional region A; then immersing one end of functional region B of the finished framework into the corresponding support slurry and performing a first drying of one end of functional region B; finally performing a first calcination of the whole to obtain a support composed of functional regions A and B; immersing one end of functional region A of the support into the corresponding catalytic component solution and performing a second drying of one end of functional region A; then immersing one end of functional region B of the support into the corresponding catalytic component solution and performing a second drying of one end of functional region B; finally performing a second calcination of the whole to obtain the flue gas nitrogen oxide reduction catalyst.

[0081] Unlike the split-type skeleton forming process, the skeleton material described above is directly processed into a complete "connected" geometric shape of the required total length. This single finished skeleton will serve as the base for both functional areas A and B.

[0082] The carrier loading step is crucial for forming a single, integrated carrier. During operation, one end of the skeleton (functional area A) is first immersed in the carrier slurry in area A to a predetermined depth, then removed and dried. Next, the other end of the skeleton (functional area B) is immersed in the carrier slurry in area B, and similarly removed and dried. The most critical step is the "final overall first firing," which involves subjecting this dried skeleton, coated with different slurries at both ends, to a single high-temperature firing, thus forming a single, semi-finished carrier with two different carrier coatings.

[0083] The catalytic component loading process is similar to that of the support loading process. First, the A functional region end of the support semi-finished product is immersed in the A region catalytic component solution, and then dried. Next, its B functional region end is immersed in the B region catalytic component solution, and then dried. Finally, similarly, a "final whole-module second calcination" is performed to conduct a final calcination of the entire catalyst module to activate all catalytic components. After completing this step, a complete, integrated functional zone catalyst is obtained.

[0084] In this application embodiment, a method for preparing the flue gas nitrogen oxide reduction catalyst as described in the foregoing embodiments is provided, wherein the drying temperature of the first drying is 90℃~120℃. For example, it can be 90℃, 100℃, 110℃, 120℃, etc.

[0085] In some embodiments, the calcination temperature of the first calcination is 500°C to 660°C. For example, it can be 500°C, 550°C, 600°C, 6500°C, etc.

[0086] In some embodiments, the drying temperature of the second drying process is 90°C to 120°C. For example, it can be 90°C, 100°C, 110°C, 120°C, etc.

[0087] In some embodiments, the calcination temperature of the second calcination is 380°C to 520°C. For example, it can be 380°C, 400°C, 450°C, 500°C, 520°C, etc.

[0088] In some embodiments, the solid content of the carrier slurry is 20% to 55%. For example, it can be 20%, 30%, 40%, 50%, 55%, etc.

[0089] In some embodiments, the viscosity of the carrier slurry is 400 mPa·s to 1800 mPa·s. For example, it can be 400 mPa·s, 500 mPa·s, 800 mPa·s, 1000 mPa·s, 1500 mPa·s, 1800 mPa·s, etc.

[0090] In some embodiments, the solid content of the catalytic component solution is 3% to 27%. For example, it can be 3%, 5%, 10%, 15%, 20%, 25%, 27%, etc.

[0091] In some embodiments, the viscosity of the catalytic component solution is 5 mPa·s to 70 mPa·s. For example, it can be 5 mPa·s, 10 mPa·s, 15 mPa·s, 20 mPa·s, 30 mPa·s, 50 mPa·s, 60 mPa·s, 70 mPa·s, etc.

[0092] This application provides a method for treating nitrogen oxides in flue gas from an ethylene cracking furnace, comprising:

[0093] The flue gas to be treated is sequentially guided through the A and B functional regions of the flue gas nitrogen oxide reduction catalyst as described in any of the foregoing embodiments.

[0094] This method is specifically designed for the industrial scenario of "ethylene cracking furnaces." Ethylene cracking furnaces are core equipment in the petrochemical industry, and their emitted flue gas is characterized by high temperature, large temperature variations, and the presence of heavy metal dust such as chromium and nickel. Therefore, this method is a technique for treating nitrogen oxides (NOx) under specific harsh operating conditions. xThis invention describes a process for purifying industrial flue gas from an ethylene cracking furnace. The target gas for treatment is the flue gas from the furnace. The equipment used is specifically limited to the special catalyst with A / B functional zones provided in the aforementioned embodiments. The treatment sequence is clearly defined: the flue gas must flow through the zone sequentially, first through functional zone A, then through functional zone B. This sequence is crucial for achieving the technical effect of this method and cannot be reversed.

[0095] The effectiveness of this method stems entirely from the unique structure of the functionally partitioned catalyst it utilizes. The entire process can be understood as a highly efficient "two-stage purification" process:

[0096] (1) First stage: Physical pretreatment (completed in functional area A): When containing heavy metals, carbon black and other dust and NO x When the flue gas first enters functional zone A, functional zone A, with its large-pore, porous structure, acts as a "protective filter." It actively intercepts and captures dust particles such as heavy metals and carbon black in the flue gas. This step completes the physical pretreatment of the flue gas, and its direct beneficial effects are: preventing blockage: avoiding the direct impact and blockage of downstream core reaction zones by dust particles, thereby preventing a sharp increase in system operating pressure differential and ensuring stable process operation.

[0097] (2) Second stage: Chemical catalytic reduction (completed in functional zone B): The relatively clean flue gas, purified in functional zone A, then enters functional zone B. As the "main reaction zone," functional zone B's catalytic active sites are protected from dust and poisoning by functional zone A. Therefore, NOx can undergo a highly efficient and continuous catalytic reduction reaction with a reducing agent (such as ammonia) here, producing harmless nitrogen and water. The beneficial effect of this step is that, because the catalyst activity is protected, NOx... x The removal efficiency can be maintained at a high level for a long period of time. In addition, the deactivation rate of the entire catalyst is greatly slowed down, which enables the treatment method to support the long-term continuous operation of the ethylene cracking furnace, reduces downtime caused by catalyst replacement, and has significant economic value.

[0098] In summary, this method cleverly links physical filtration and chemical catalysis by forcibly specifying the order in which flue gas flows through a specific catalyst. This synergistically solves the dual problems of catalyst clogging and poisoning in existing technologies, thus providing a more stable, longer-lasting, and more efficient flue gas treatment solution in harsh industrial environments.

[0099] For example, specific methods for treating nitrogen oxides in flue gas from ethylene cracking furnaces may include:

[0100] (1) Catalyst encapsulation: The prepared catalyst is encapsulated in a metal shell. When separated, they are encapsulated separately. Functional area A and functional area B are connected by the shell and the shell is connected by a male and female buckle.

[0101] (2) Catalyst installation: The packaged catalyst is installed on the support frame in the ethylene cracking furnace, with functional area A facing the flue gas inlet. A stainless steel screen (40 mesh) is installed at the inlet to intercept large foreign objects.

[0102] (3) Flue gas treatment: The flue gas to be treated is controlled to be guided through the A and B functional zones of the flue gas nitrogen oxide reduction catalyst in sequence.

[0103] The present invention will be further illustrated below with specific embodiments. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0104] Example 1

[0105] In this embodiment, a flue gas nitrogen oxide reduction catalyst is prepared, installed, and used for flue gas treatment.

[0106] Experimental methods:

[0107] A three-dimensional corrugated plate catalyst with functional zones A and B was prepared using a glass fiber paper skeleton. The total height of the catalyst was 810 mm. The height of functional zone A was 270 mm, accounting for 33.3%, and the height of functional zone B was 540 mm, accounting for 66.7%.

[0108] Functional Area A: The carrier is γ-alumina, accounting for 81.6%. The catalytic components include magnesium oxide (7%), cerium oxide (3.5%), and alumina (6%). Guava powder is used as the pore control agent, with an addition ratio of 1.9%. The precursors for magnesium oxide, cerium oxide, and alumina in the above materials are nitrates; the rest are the bulk materials. Glass fiber paper is prepared into a corrugated shape with a wave height of 4.0 mm and a wavelength of 8 mm. A carrier slurry with a solid content of 38% and a viscosity of 650 mPa·s is prepared according to the specified ratio. The formed corrugated board skeleton material is immersed in the carrier slurry, then dried and calcined. The drying temperature is 105℃, the calcination temperature is 600℃, and the calcination time is constant for 3 hours. A catalytic component solution for functional region A was prepared, with a solid content of 11% and a viscosity of 9.6 mPa·s. The support for functional region A was immersed in the catalytic component solution, dried, and calcined. The drying temperature was 105℃, and the calcination temperature was 400℃ for 2 hours to obtain functional region A. The average pore size of functional region A ranged from 8 to 42 μm, and the specific surface area was 229 m². 2 / g.

[0109] Functional Zone B: The carriers are titanium dioxide and zirconium oxide, with titanium dioxide accounting for 80.4% and zirconium oxide accounting for 4.6%. The catalytic components include vanadium pentoxide, tungsten trioxide, molybdenum trioxide, and niobium pentoxide. Vanadium pentoxide accounts for 3.2%, tungsten trioxide for 8.5%, molybdenum trioxide for 2.7%, and niobium pentoxide for 0.6%. The precursors for zirconium oxide, molybdenum trioxide, and niobium pentoxide are nitrates, while vanadium pentoxide and tungsten trioxide are ammonium salts; the rest are the bulk materials. Glass fiber paper is prepared into a corrugated shape with a wave height of 4.0 mm and a wavelength of 8 mm. A carrier slurry with a solid content of 35% and a viscosity of 510 mPa·s is prepared according to the specified ratio. The formed corrugated board skeleton material is immersed in the carrier slurry, then dried and calcined. The drying temperature is 105℃, the calcination temperature is 520℃, and the calcination time is constant for 4 hours. A solution of the B-functional region catalytic component was prepared with a solid content of 16% and a viscosity of 11 mPa·s. The B-functional region support was immersed in the catalytic component solution, dried, and calcined. The drying temperature was 105℃, the calcination temperature was 430℃, and the calcination time was maintained at this temperature for 2.5 hours, thus obtaining the B-functional region catalyst. The average pore size of the B-functional region ranged from 4 to 20 nm, and the specific surface area was 79 m². 2 / g.

[0110] The A and B functional zones can be used by encapsulating the corrugated plate catalyst separately in a metal shell. The A and B functional zones are connected by a snap-fit ​​mechanism in the shell. The A functional zone is the flue gas inlet, and the B functional zone is the flue gas outlet.

[0111] Example 2

[0112] In this embodiment, a flue gas nitrogen oxide reduction catalyst is prepared, installed, and used for flue gas treatment.

[0113] Experimental methods:

[0114] A corrugated plate catalyst with integrated functional zones A and B was prepared using a glass fiber paper skeleton, with a total catalyst height of 750 mm. Functional zone A has a height of 210 mm, accounting for 28% of the total height, while functional zone B has a height of 540 mm, accounting for 72% of the total height.

[0115] Functional Zone A: The carrier is γ-alumina, with a proportion of 78%. Functional Zone B: The carrier is titanium dioxide and zirconium oxide, with titanium dioxide accounting for 78.7% and zirconium oxide accounting for 6%. The carrier slurry for Functional Zone A is prepared according to the proportions, with a solid content of 38% and a viscosity of 650 mPa·s. The carrier slurry for Functional Zone B is prepared according to the proportions, with a solid content of 35% and a viscosity of 510 mPa·s. Glass fiber paper is prepared into a corrugated shape with a wave height of 4.0 mm and a wavelength of 8 mm. It is first immersed in the carrier slurry for Functional Zone A to a depth of 210 mm, dried, and then the other end is immersed in the carrier slurry for Functional Zone B, dried, and then the entire piece is calcined. The drying temperature is 105℃, the calcination temperature is 600℃, and the calcination time is constant for 3 hours.

[0116] The catalytic components in functional zone A include magnesium oxide (8%), cerium oxide (4%), and aluminum oxide (7%). Starch is used as the pore control agent at a concentration of 3%. The precursors for magnesium oxide, cerium oxide, and aluminum oxide are nitrates; the rest are bulk materials. The catalytic components in functional zone B include vanadium pentoxide, tungsten trioxide, molybdenum trioxide, and niobium pentoxide. Vanadium pentoxide accounts for 3.5%, tungsten trioxide for 8%, molybdenum trioxide for 3%, and niobium pentoxide for 0.8%. The precursors for zirconium oxide, molybdenum trioxide, and niobium pentoxide are nitrates; vanadium pentoxide and tungsten trioxide are ammonium salts; the rest are bulk materials.

[0117] The catalytic component solution for functional zone A was prepared according to the formula ratio, with a solid content of 12.5% ​​and a viscosity of 10.3 mPa·s; the catalytic component solution for functional zone B was prepared according to the formula ratio, with a solid content of 17.9% and a viscosity of 13.2 mPa·s.

[0118] The A functional region of the integrated support was immersed in a solution of A functional catalytic components and dried. Then, the B functional region at the other end was immersed in a solution of B functional catalytic components and dried. The entire assembly was then calcined at 105℃ and 400℃ for 2 hours to obtain an integrated corrugated plate catalyst with A and B functional regions. The average pore size of the A functional region ranged from 10 μm to 49 μm, and the specific surface area was 233 m². 2 / g, the average pore size of functional region B ranges from 6 nm to 17 nm, and the specific surface area is 74 m². 2 / g. The integrated corrugated plate catalyst can be used by encapsulating it in a metal shell, where functional area A is the flue gas inlet and functional area B is the flue gas outlet.

[0119] Comparative Example 1

[0120] In this comparative example, a catalyst was installed and flue gas was treated.

[0121] Experimental methods:

[0122] The commonly used corrugated plate catalyst for ethylene cracking furnaces, model DNX-LD, is adopted.

[0123] The catalyst has a total height of 810 mm and consists of two layers: a lower layer with a height of 270 mm and an upper layer with a height of 540 mm. The catalyst has a wavelength of 8 mm and a height of 4.0 mm. The catalyst support is titanium dioxide (84.3%), and the catalytic components are vanadium pentoxide (3.8%) and tungsten trioxide (11.9%). The average pore size of the catalyst ranges from 2 nm to 19 nm, and the specific surface area is 77 m². 2 / g.

[0124] The two catalyst layers are encapsulated in a metal shell. The catalyst with a height of 270 mm is the flue gas inlet, and the catalyst with a height of 540 mm is the flue gas outlet.

[0125] Test experiment:

[0126] 1. Experimental Method:

[0127] The above three groups of catalysts were placed on an ethylene cracking furnace simulation test platform for performance testing.

[0128] (1) Test conditions: flue gas composition: NO x 800 ppm, NH3 800 ppm, SO2 50 ppm, O2 5%, H2O 8%, the remainder is nitrogen.

[0129] (2) Dust content: Prepare quartz sand dust with 5% chromium oxide and nickel oxide, concentration 200 mg / m³. 3 .

[0130] (3) Airspeed: 6000 h -1 ;

[0131] (4) Temperature: 450℃.

[0132] 2. Experimental Results:

[0133] After 720 hours of online testing, the results are shown in Table 1. Figure 3 and Figure 4 Example 1 ( Figure 3 ) and comparative examples ( Figure 4 Scanning electron microscope image of the catalyst inlet after use.

[0134] Table 1. Performance test results of the examples and comparative examples after 720 hours.

[0135]

[0136] 3. Analysis:

[0137] Refer to the data in Table 1 and Figure 3 To verify the technical effectiveness of the flue gas nitrogen oxide reduction catalyst provided in this application, Example 1 (split-type functional zone catalyst), Example 2 (integrated functional zone catalyst), and Comparative Example 1 (conventional commercially available catalyst without functional zones) were subjected to a 720-hour continuous performance test under simulated ethylene cracking furnace flue gas (containing heavy metal dust). The test results are shown in Table 1. Through in-depth analysis of the data in Table 1, the following conclusions can be drawn:

[0138] (1) Regarding the operating pressure differential, the primary problem this application aims to solve is the clogging of the catalyst in the dust-laden flue gas. As can be seen from the "Operating Pressure Differential" data in Table 1, after 720 hours of operation, the operating pressure differentials of Example 1 and Example 2 were 86 Pa and 88 Pa, respectively, remaining at a low and basically stable level. In stark contrast, the operating pressure differential of Comparative Example 1 increased sharply to 126 Pa, far exceeding that of the Examples.

[0139] The fundamental reason for this significant difference lies in the A / B functional zone design adopted in the technical solution of this application. The A functional zone in Examples 1 and 2 is designed as a porous structure with large pore size (e.g., the average pore size range of Example 1 is 8μm~42μm) and high specific surface area, specifically for intercepting heavy metal dust in flue gas. (See attached...) Figure 3 (Electron micrograph of Example 1) shows that dust particles are effectively captured and dispersed within the loose framework structure of functional region A, without forming a dense blocking layer. Comparative Example 1 uses a traditional homogeneous catalyst with a relatively small overall average pore size (2 nm~19 nm), lacking specialized dust interception and containment capabilities. Therefore, during the test, heavy metal dust directly impacts and accumulates at the catalyst inlet, as shown in the attached image. Figure 4 As shown, a dense covering layer formed, severely clogging the flue gas passage and causing a significant increase in its operating pressure differential. Experimental data strongly demonstrates that the design of functional zone A effectively solves the clogging problem of existing technologies, ensuring the long-term stable operation of the system.

[0140] (2) Regarding NO x Conversion rate; the ultimate goal of this application is the efficient removal of nitrogen oxides. From "NO..." x The conversion rate data shows that after 720 hours of operation, Examples 1 and 2 still maintained NO conversion rates as high as 94.5% and 93.8%, respectively. x Conversion rate. And compared to NO in ratio 1... x The conversion rate dropped to 86.2%.

[0141] This performance difference is also attributed to the synergistic effect of functional zones A and B. In Examples 1 and 2, functional zone A, acting as a physical barrier, successfully intercepted catalytically toxic heavy metal dust, creating a clean reaction environment for the downstream functional zone B. This protected the active sites in functional zone B (the main reaction zone) from physical covering and chemical poisoning, allowing them to maintain their inherent high catalytic activity for a long time. In contrast, the catalyst in Comparative Example 1 had all its active sites directly exposed to dusty flue gas. The dust covering and heavy metal poisoning caused a large number of its active sites to become inactive, and its catalytic performance declined significantly over time. Therefore, this data proves that the technical solution of this application effectively solves the problem of catalyst poisoning and deactivation by protecting the main reaction zone, ensuring long-term and efficient denitrification performance.

[0142] (3) Specific surface area is a key physical parameter for evaluating catalyst activity, and its degradation directly reflects the catalyst's stability. Test results show that after use, the specific surface area of ​​the core reaction zone (functional zone B) in Examples 1 and 2 reached as high as 78 m². 2 / g and 74 m 2 / g, compared to its initial value (79 m) 2 / g and 74 m 2 Compared to (g), there was almost no decrease in specific surface area. However, the specific surface area of ​​Comparative Example 1 decreased sharply to 47 m². 2 / g, compared to its initial value (77 m) 2 / g) decreased by nearly 40%.

[0143] This result verifies the superiority of the technical solution in this application at the material level. First, the protective effect of functional region A reduces the damage of dust to the structure of functional region B. Second, the support and catalytic components of functional region B in the embodiment have undergone special design (for example, zirconium oxide resistant to high-temperature sintering is added to the support, and tungsten trioxide and niobium pentoxide to enhance thermal stability are added to the catalytic components), giving it excellent resistance to high-temperature sintering. In contrast, the conventional catalyst in Comparative Example 1 underwent severe sintering and structural collapse under the dual effects of high temperature and dust, resulting in a significant reduction in specific surface area, which is the fundamental reason for its decreased NOx conversion rate. This data fully demonstrates that the technical solution of this application successfully solves the problem of easy sintering and deactivation in existing technologies under high temperature and dusty environments.

[0144] (4) Regarding SO2 conversion rate, data show that the SO2 conversion rates of Examples 1 and 2 are both below 1%, while that of Comparative Example 1 is 1.2%. A lower SO2 conversion rate is an advantageous technical indicator in SCR reactions because it reduces SO3 formation, thereby inhibiting the formation of byproducts such as ammonium bisulfate and avoiding additional clogging and corrosion problems. This is due to the addition of molybdenum trioxide to the catalytic component in functional zone B of the examples, which effectively inhibits the oxidation reaction of SO2.

[0145] In summary, a comprehensive analysis of the test data confirms that the A / B functional partition catalyst proposed in this application, through its innovative structural design and optimized material composition, successfully solves the three major technical challenges of clogging, poisoning, and high-temperature sintering in the flue gas environment of ethylene cracking furnaces, while maintaining extremely high NO levels. x While achieving high conversion rates, it also demonstrates excellent operational stability and a longer service life, fully achieving the invention objectives of this application.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A catalyst for reducing nitrogen oxides in flue gas, characterized in that, The flue gas nitrogen oxide reduction catalyst is arranged in functional zones A and B sequentially along the flue gas flow direction; The A functional region is located at the inlet end of the flue gas nitrogen oxide reduction catalyst and is a porous structure for intercepting dust in the flue gas; the dust includes heavy metals and / or carbon black; the average pore size of the A functional region ranges from 2 μm to 50 μm; the average pore size of the B functional region ranges from 2 nm to 20 nm. The functional region A is composed of a first framework, a first support, and a first catalytic component; the first catalytic component includes magnesium oxide, cerium oxide, and aluminum oxide; the first framework includes at least one of glass fiber paper, glass fiber mat, and metal mesh; the first support is γ-alumina. The B functional region is composed of a second framework, a second support, and a second catalytic component; the second framework includes at least one of glass fiber paper, glass fiber mat, and metal mesh; the second support is a mixture of titanium dioxide and zirconium oxide; the second catalytic component includes vanadium pentoxide, tungsten trioxide, molybdenum trioxide, and niobium pentoxide. The B functional region is located downstream of the A functional region and is the main reaction region for the catalytic reduction of nitrogen oxides.

2. The flue gas nitrogen oxide reduction catalyst as described in claim 1, characterized in that, The flue gas nitrogen oxide reduction catalyst is an integral structure composed of functional region A and functional region B; or, the flue gas nitrogen oxide reduction catalyst is a split structure composed of two separate catalysts, functional regions A and B, which can be separated and longitudinally spliced ​​together along the flue gas flow direction.

3. The flue gas nitrogen oxide reduction catalyst as described in claim 1, characterized in that, The shape of the flue gas nitrogen oxide reduction catalyst is corrugated plate, honeycomb or flat plate.

4. The flue gas nitrogen oxide reduction catalyst as described in claim 1, characterized in that, The height of functional zone A accounts for 5% to 40% of the longitudinal height of the flue gas nitrogen oxide reduction catalyst.

5. The flue gas nitrogen oxide reduction catalyst as described in claim 1, characterized in that, The height of functional zone B accounts for 60% to 95% of the longitudinal height of the flue gas nitrogen oxide reduction catalyst.

6. The flue gas nitrogen oxide reduction catalyst as described in claim 1, characterized in that, The specific surface area of ​​functional area A is greater than 200 m². 2 / g.

7. The flue gas nitrogen oxide reduction catalyst as described in claim 1, characterized in that, The specific surface area of ​​functional zone B is greater than 70m². 2 / g.

8. The flue gas nitrogen oxide reduction catalyst as described in claim 1, characterized in that, In the first catalytic component of functional region A, the mass percentage of magnesium oxide is 5% to 10%, the mass percentage of cerium oxide is 3% to 5%, and the mass percentage of aluminum oxide is 4% to 9%.

9. The flue gas nitrogen oxide reduction catalyst as described in claim 1, characterized in that, The A functional area is also equipped with a pore control agent; The pore control agent includes at least one of guar gum powder, rice husk powder, starch, graphite and cellulose; and / or the addition ratio of the pore control agent is 1% to 4%.

10. The flue gas nitrogen oxide reduction catalyst according to claim 1, characterized in that, In the second carrier of the B functional area, the mass percentage of zirconium oxide is 4% to 18%.

11. The flue gas nitrogen oxide reduction catalyst according to claim 1, characterized in that, In the second catalytic component of the B functional region, the mass percentage of vanadium pentoxide is 1% to 9%, the mass percentage of tungsten trioxide is 5% to 15%, the mass percentage of molybdenum trioxide is 2% to 5%, and the mass percentage of niobium pentoxide is 0.2% to 2.5%.

12. A method for preparing a flue gas nitrogen oxide reduction catalyst as described in any one of claims 1-11, characterized in that, The flue gas nitrogen oxide reduction catalyst can be either an integral structure or a split structure. When the flue gas nitrogen oxide reduction catalyst has a split structure, the preparation method of the flue gas nitrogen oxide reduction catalyst includes: preparing the framework materials of functional regions A and B into corresponding geometric shapes as finished frameworks; preparing support slurries for functional regions A and B, immersing the finished frameworks into the corresponding support slurries, and obtaining the supports corresponding to functional regions A and B through a first drying and a first calcination; immersing the supports into corresponding catalytic component solutions, and performing a second drying and a second calcination to obtain functional regions A and B; and / or, When the flue gas nitrogen oxide reduction catalyst is an integral structure, the preparation method of the flue gas nitrogen oxide reduction catalyst includes: preparing an integral geometric shape based on the framework materials of functional regions A and B, as a finished framework; preparing support slurries for functional regions A and B respectively; immersing one end of functional region A of the finished framework into the corresponding support slurry for a first drying of one end of functional region A; then immersing one end of functional region B of the finished framework into the corresponding support slurry for a first drying of one end of functional region B; and finally performing a first calcination on the whole to obtain a support composed of functional regions A and B; immersing one end of functional region A of the support into a corresponding catalytic component solution for a second drying of one end of functional region A; then immersing one end of functional region B of the support into the corresponding catalytic component solution for a second drying of one end of functional region B; and finally performing a second calcination on the whole to obtain the flue gas nitrogen oxide reduction catalyst.

13. The method for preparing the flue gas nitrogen oxide reduction catalyst as described in claim 12, characterized in that, The drying temperature of the first drying process is 90℃~120℃.

14. The method for preparing the flue gas nitrogen oxide reduction catalyst as described in claim 12, characterized in that, The roasting temperature for the first roasting is 500℃~660℃.

15. The method for preparing the flue gas nitrogen oxide reduction catalyst as described in claim 12, characterized in that, The drying temperature for the second drying process is 90℃~120℃.

16. The method for preparing the flue gas nitrogen oxide reduction catalyst as described in claim 12, characterized in that, The second roasting temperature is 380℃~520℃.

17. The method for preparing the flue gas nitrogen oxide reduction catalyst as described in claim 12, characterized in that, The solid content of the carrier slurry is 20% to 55%.

18. The method for preparing the flue gas nitrogen oxide reduction catalyst as described in claim 12, characterized in that, The viscosity of the carrier slurry is 400 mPa·s to 1800 mPa·s.

19. The method for preparing the flue gas nitrogen oxide reduction catalyst as described in claim 12, characterized in that, The solid content of the catalytic component solution is 3% to 27%.

20. The method for preparing the flue gas nitrogen oxide reduction catalyst as described in claim 12, characterized in that, The viscosity of the catalytic component solution is 5 mPa·s to 70 mPa·s.

21. A method for treating nitrogen oxides in flue gas from an ethylene cracking furnace, characterized in that, include: The flue gas to be treated is sequentially guided through functional regions A and B of the flue gas nitrogen oxide reduction catalyst as described in any one of claims 1-11.

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