Recycling method of renewable fine SCR (Selective Catalytic Reduction) denitration catalyst system

Abstract

The invention relates to a recycling method of a reproducible fine SCR (Selective Catalytic Reduction) denitration catalyst system, and the reproducible fine SCR denitration catalyst system comprises a catalyst module containing a reproducible low-temperature SCR denitration catalyst; a reactor for accommodating the catalyst module; the injection system is used for injecting a reducing agent into the reactor, and the low-temperature SCR denitration catalyst comprises a thermoplastic carrier framework; the low-temperature SCR denitration catalytic active component is compounded in the carrier framework. The method comprises the following steps: taking out a deactivated catalyst module from a reactor; the method comprises the following steps: carrying out pretreatment before regeneration on the inactivated low-temperature SCR denitration catalyst; the pretreated low-temperature SCR denitration catalyst is re-formed, and regeneration of the low-temperature SCR denitration catalyst is achieved while re-forming is conducted; and filling the regenerated low-temperature SCR denitration catalyst into the catalyst module, and reinstalling the catalyst module into the reactor to realize the recycling of the fine SCR denitration catalyst system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of SCR catalysts, and in particular to a fine SCR denitration catalyst and system, structure, configuration, and corresponding process method for nitrogen oxides (NO x ). More specifically, the present application relates to a recycling method for a regenerable fine SCR denitration catalyst system. BACKGROUND

[0002] Nitrogen oxides (NO x ) are one of the most important atmospheric pollutants at present, and their excessive emission not only seriously threatens human health, but also causes a series of environmental problems. At present, the proportion of flue gas NO x emission in non-electricity industries in China is increasing year by year, and achieving flue gas emission reduction in non-electricity industries is the focus of atmospheric pollution prevention and control work at the present stage.

[0003] Research and practice have found that ammonia-selective catalytic reduction (NH3-SCR) is the most mature technology for controlling NO x emission at present, and is one of the best technologies for controlling NO x emission, and the catalyst is the core of the SCR technology.

[0004] At present, the mainstream commercialized SCR denitration catalyst is a vanadium-based monolithic honeycomb catalyst (V2O5-WO3-TiO2), and its catalyst forming technology includes monolithic honeycomb forming, plate forming, and corrugated plate forming, and is mainly prepared using titanium white powder as the paste material. Not only is the preparation process complex, but also it cannot tolerate errors. Once the forming process deviates from the optimal working condition of the forming process, the catalyst cannot meet the use requirements and is discarded. Moreover, the catalyst is prone to breakage during transportation, resulting in product loss. In addition, due to the large density of this type of vanadium-based catalyst, it is difficult to apply it in equipment scenes such as ships and cars that have strict requirements on the weight of the catalyst.

[0005] In addition, the desired denitration temperature of flue gas of large-scale non-fire power plant, cement kiln, industrial boiler and the like is mostly below 300°C. The existing low-temperature denitration catalyst is easily affected by fly ash, SO2, H2O and the like in the actual production operation process, leading to rapid deactivation of the catalyst and inability to be used normally for a long time. The used catalyst (which cannot meet the denitration requirements due to wear or deactivation and the like) is generally discarded directly, which not only wastes resources but also easily causes environmental pollution by being discarded at will. Although there are currently some studies on cleaning and regeneration of the catalyst, such as cleaning by ultrasonic cleaning and then acid / alkali washing and the like to restore the activity. However, in the production process of the existing technology, on the one hand, the cost of cleaning and regeneration of the catalyst is relatively high (about 40% of the price of a new catalyst, and the chemical life is 80% of that of a new catalyst), and the catalyst after multiple services cannot be recycled, which is not a recycling method with economic and environmental benefits. On the other hand, the chemical cleaning process generally inevitably causes pollution. In other words, the disposal and recycling of the catalyst also causes more costs, more complex post-treatment and more serious environmental pollution and the like.

[0006] The technology of loading a catalyst with a noble metal base by impregnation method, although it is beneficial to the recovery and utilization of the noble metal component to a certain extent, still has other losses in the extraction and filtration process, so that the noble metal active substance cannot be completely recovered. Moreover, the recovery process still causes a large amount of wastewater, some toxic gases and only a low recovery rate, and the process method needs to be further improved.

[0007] The existing vanadium-based catalyst (V2O5-WO3TiO2) has problems of complex preparation process (calcination for 20-30 days is required), low mechanical strength (easy to be broken during transportation), difficulty in regeneration (acid / alkali washing is required, and the cost is high) and environmental pollution and the like. In addition, the low-temperature denitration catalyst is easily poisoned by SO2 and H2O, and the disposal cost of the discarded catalyst is high and the environment is polluted.

[0008] The advanced preparation technology and regeneration technology of the industrial denitration catalyst after deactivation are still a big problem to be solved for the denitration catalyst at present.

[0009] In actual production and application of enterprises, the yield of catalyst preparation, breakage during transportation and deactivation of the catalyst in the actual working environment are difficult to avoid, and there is a long-term demand in the industry that the catalyst can be operated stably, with high performance and high reliability, for a longer time at a lower price. However, the current preparation and regeneration technology cannot make the catalyst have a relatively low operating cost and always maintain a relatively high catalytic activity.

[0010] Moreover, the spent catalysts cannot be easily disposed of in an environmentally friendly manner because they contain harmful substances such as heavy metals, which can easily enter the environment during loading, transportation, storage, and disposal, and then harm the environment and the health of living beings (including humans) through contact, inhalation, and food chain, and even cause cancer. Some spent catalysts also contain toxic components such as arsenic trioxide, arsenic pentoxide, chromium trioxide (as an example, not a common toxic component in denitration catalysts, can be replaced by vanadium pentoxide, a common component in denitration catalysts), and the like. If not properly disposed of, they will occupy space, pollute water and soil, release harmful gases, and increase air particulate matter. If properly disposed of to meet environmental and legal requirements, the high cost of materials, equipment, and processes required to dispose of the waste makes it essentially impractical for industrial use. The above chemical waste catalysts, including the above-mentioned spent catalysts, cannot be treated as general solid waste and must be entrusted to professional units with hazardous waste operating permits for recycling, utilization, and disposal to prevent environmental risks and ensure health and safety.

[0011] A Chinese patent application for invention with publication number CN117019136A, filed by the same inventor as this application on July 28, 2023, discloses a monolithic low-temperature manganese / cerium honeycomb denitration catalyst, which is prepared by using cerium dioxide (CeO2) and manganese oxide (MnO x ) as the main active components, titanium dioxide (TiO2) as the paste material, and adding a structure aid, and using an extrusion method. The catalyst was evaluated for catalytic activity and SO2 poisoning resistance by simulating the test environment of actual industrial flue gas. Experimental data show that the catalyst exhibits excellent low-temperature denitration activity and SO2 poisoning resistance, and can achieve removal of nitrogen oxides in low-temperature flue gas in actual industrial applications.

[0012] However, the existing catalyst preparation process uses inorganic materials such as TiO2 as the paste material, which is prone to sintering and will lose adhesion after multiple calcinations, making it impossible to use normally; the yield of the catalyst, damage during transportation, and deactivation of the catalyst in actual working conditions are difficult to avoid. The TiO2 material after multiple calcinations will reduce the mechanical strength of the formed catalyst and damage the structure, resulting in the catalyst being scrapped due to inability to use. Moreover, the mechanical strength of the catalyst prepared using TiO2 as the paste material is limited, and the catalyst is brittle, which can easily cause damage and breakage during transportation and use.

[0013] In addition, in the recycling and disposal of spent catalysts, such as catalyst regeneration and hazardous waste disposal, the recovery of active components from a large amount of TiO2 requires a large amount of energy, resulting in a large amount of energy waste and environmental pollution problems.

[0014] In summary, the catalyst regeneration, recycling treatment technology of the prior art is difficult, high cost, and the technical effect and economic benefit are not good, so it is not widely used and has a bleak prospect; the treatment of hazardous waste of the catalyst of the prior art is easy to cause resource waste and environmental pollution; the activity substance extraction technology of the catalyst in recycling of the prior art, such as hydrometallurgy, pyrometallurgy and other process methods, is complicated, high energy consumption and time-consuming; the cleaning and active substance reloading (packing) of the catalyst in regeneration of the prior art not only has complicated process steps, but also affects the mechanical strength of the final regenerated catalyst product and greatly reduces the catalytic performance of the regenerated catalyst; the paste remolding of the catalyst in regeneration and waste treatment of the prior art affects the mechanical strength, and the hazardous waste needs special treatment.

[0015] Therefore, based at least on the above, there is a continuing need in the industry to innovate and create in the related preparation, material, structure, molding, regeneration and other technologies of the SCR catalyst, and to improve the existing catalyst molding and other technical modes. It is desirable to innovatively improve or realize a repeatedly molded, easy-to-process and material-recycled, regenerated and recycled molded catalyst and its preparation process, to reduce or even overcome the defects of the prior art, and to achieve more beneficial technical effects and technical progress. SUMMARY

[0016] The present application is proposed in view of the above and other more ideas.

[0017] The inventors of the present application surprisingly found through research and repeatedly tested and verified that the polymer (as a substrate / carrier / skeleton) supported catalyst can be regenerated and reused. The present application proves through research and testing that the polymer substrate (or carrier / skeleton) supported catalyst can be regenerated by a simplified remolding process suitable for industrial scale production, realize multiple uses, greatly reduce material and production costs, and greatly reduce or even substantially eliminate negative impacts on the environment.

[0018] One of the purposes of the present application is to provide a recycling method of a fine SCR denitration catalyst system which can be (repeatedly) regenerated. The fine SCR denitration catalyst system has a replaceable / reshapable regenerable low-temperature SCR catalyst module, which uses a thermoplastic as a carrier skeleton and contains a low-temperature SCR catalytically active component dispersed and supported in the carrier skeleton formed of the thermoplastic. Thus, the fine SCR denitration catalyst system of the present application can also be reshaped and regenerated by the preparation, reshaping and regeneration of the low-temperature SCR catalyst, and can achieve easier replacement / reshaping and regeneration and fine SCR denitration by, but not limited to, the segmented configuration of the catalyst module. In the recycling method, the low-temperature SCR denitration catalyst can be reshaped, and the regeneration of the low-temperature SCR denitration catalyst can be achieved at the same time of reshaping, so as to achieve the recycling of the fine SCR denitration catalyst system.

[0019] The inventors of the present application have surprisingly found that, by using a thermoplastic catalyst molding process, the thermoplastic material can be used instead of TiO2 and the like as the skeleton (carrier) material of the catalyst; at the same time, the powder catalyst component can be used as a binder for the thermoplastic material to help the various components / structures of the molded thermoplastic-based SCR catalyst to be better bonded and combined together. Finally, by the concept and technology of the present application, the powder catalyst thermoplastic is molded for the first time and repeatedly molded into an industrial catalyst which has substantially stable and unchanged catalyst activity, stable surface physical and chemical properties, firmness and lightness, and can be repeatedly reshaped and regenerated, which can replace the existing low-temperature denitration catalyst and can be applied to a wide range of application fields including ships, automobiles, thermal power plants, incineration plants, cement plants, gas scrubbing equipment and the like which require lightweight catalysts.

[0020] According to one aspect of the basic application concept of the present application, a low-temperature SCR catalyst is provided, in which a thermoplastic is used instead of a conventional carrier material such as TiO2 as a conventional skeleton (carrier) material, the preparation process is simplified by a thermoplastic / thermopressing / extrusion molding process and the like, and the pore / channel structure of the catalyst can be selectively increased by a pore-forming agent. The low-temperature SCR catalyst can be regenerated by reshaping after crushing after deactivation, so as to achieve regeneration and recycling.

[0021] Some important aspects of the inventive concept of the present application are further described as follows:

[0022] (1) The thermoplastic can be used instead of a conventional carrier material such as TiO2 as a catalyst carrier skeleton material, so as to simplify and facilitate the preparation process and regeneration process of the catalyst.

[0023] The industrial denitration catalyst (nitrogen oxides (NO xGenerally, TiO2 and other materials are used as the main paste material, and active components are mixed into the mud during the molding process or are impregnated into the support material after the preparation of the support material, and then the finished catalyst is obtained after calcination and cutting. The calcination process causes the active substance to precipitate from the solution and also causes the support material to sinter and thus adhere more closely together. The production of a batch of catalysts requires processes such as mixing, kneading, aging, extrusion, drying, calcination, and cutting, which takes about 20-30 days. The present application uses thermoplastic plastic as the carrier skeleton material instead of the existing process, which only needs to mix the thermoplastic plastic powder and the catalyst powder, and then perform a thermoplastic process in a mold. Due to the special surface properties of the plastic material, there is almost no mold sticking, and the desired monolithic catalyst material can be obtained from the raw materials in a very short time. The preparation by hot pressing method only takes a shorter time. The method disclosed in the present application is limited by the hot melting temperature of the plastic material, which is lower than the calcination temperature of TiO2 material and requires a shorter heating time, without the need for a drying process, and the integrated rapid forming.

[0024] (2) The low-temperature denitration catalyst is loaded on the polymer material (i.e. thermoplastic plastic material) to perform integrated monolithic forming, thereby improving the mechanical strength of the monolithic catalyst.

[0025] The traditional process for preparing industrial catalysts generally uses TiO2 and other materials as the main paste material, which has a certain mechanical strength. However, different denitration catalysts use different active components, and the addition of active components can improve the catalytic activity of the catalyst, but too much active component will reduce the adhesion of the TiO2 paste, leading to embryo body cracking, damage, and other problems during the drying process. Even if there is no cracking or damage during the preparation process, there is still a probability of catalyst cracking and damage after calcination due to uneven heating and excessive active component in some areas. More likely, the catalyst prepared from TiO2 and other materials is prone to crushing and collision during transportation, resulting in cracking and damage. In addition, catalysts with insufficient mechanical strength will collapse and crack due to excessive flue gas flow rate during use, which cannot be used anymore.

[0026] The preparation method using thermoplastic plastic as the carrier skeleton material introduced in the present application can use thermoplastic plastic material as the main body of the catalyst, which has stable physical and chemical properties and excellent mechanical strength. The catalyst can maintain the integrity of the structure during normal transportation and use, and can withstand greater flue gas pressure drop. In the preparation process, only a thermoplastic process is needed, which greatly simplifies the process flow, reduces the possibility of low yield caused by the process flow, and allows waste catalysts caused by misoperation to be remolded, saving resources.

[0027] In addition, various thermoplastics can be used to support the catalyst material stably and smoothly because their softening temperatures are higher than the working temperature window of the catalyst.

[0028] (3) The addition of pore-forming agents provides more pore structures for the catalyst

[0029] During the thermoplastic molding process, bubbles and cavities are generated due to uneven heating in the mold, which is undesirable in the preparation of plastic parts, but is desirable in the preparation of catalysts. The bubbles and channel structures can effectively increase the specific surface area and expose more active sites of the catalyst, thereby improving the catalytic activity. On this basis, we added pore-forming agents during the thermoplastic process and increased the water washing / solution immersion process to remove them (e.g., by dissolution), so that the final product can have more pore structures.

[0030] (4) Simplify the catalyst regeneration process and make the catalyst recyclable.

[0031] The main reasons for catalyst deactivation are fly ash blocking the catalyst pores and the catalyst being affected by SO2 and H2O, which leads to catalyst deactivation. For deactivated catalysts, we can simply clean them by washing off the fly ash and deposited ammonium sulfate salt components on the surface of the catalyst, then physically crush the shaped catalyst into powder, and then perform the thermoplastic molding process again. During the crushing process, all the crushed powder samples are collected, and during the reshaping process, only a small amount of catalyst powder needs to be added. After reshaping, the sample size hardly changes, the catalytic activity does not decrease, and the catalyst can almost be recycled.

[0032] (5) Change of substrate material to make the catalyst resistant to water poisoning.

[0033] Polymer materials can be used as catalyst carriers to solve the problem of water poisoning due to their stable physical and chemical properties and non-wetting surfaces. In other catalytic reactions, polymer substrates can effectively promote the rapid departure of water and improve reaction activity. Physical mixing of catalyst powder and hydrophobic polymer materials has been proven to improve the water poisoning resistance of the catalyst. This application uses thermoplastics as catalyst carrier materials. After the catalyst powder and thermoplastics are thoroughly mixed, for example, thermoplastic molding, there may be an immersion process during preparation, but it does not affect the catalytic activity of the catalyst because the hydrophobic polymer matrix material makes the catalyst have good water poisoning resistance.

[0034] According to the concept of one aspect of the present application, there is provided a recycling method of a regenerable fine SCR denitration catalyst system, the regenerable fine SCR denitration catalyst system comprising: a catalyst module containing a regenerable low-temperature SCR denitration catalyst, wherein the working temperature of the low-temperature SCR catalyst is below 300°C; a reactor for accommodating the catalyst module; and a spraying system for spraying a reducing agent into the reactor, the regenerable low-temperature SCR denitration catalyst comprising: a carrier skeleton formed of a thermoplastic plastic; and a low-temperature SCR denitration catalytically active component compounded in and supported by the carrier skeleton, the recycling method comprising: taking out the catalyst module whose low-temperature SCR denitration catalyst has been deactivated from the reactor; pre-treating the low-temperature SCR denitration catalyst of the catalyst module whose low-temperature SCR denitration catalyst has been deactivated before regeneration; re-molding the low-temperature SCR denitration catalyst after the pre-treatment, wherein the regeneration of the low-temperature SCR denitration catalyst is realized at the same time as the re-molding; and packing the regenerated low-temperature SCR denitration catalyst back into the catalyst module, and then re-packing the catalyst module back into the reactor, thereby realizing the recycling of the fine SCR denitration catalyst system.

[0035] According to one embodiment, the pre-treatment comprises the following step: crushing the low-temperature SCR denitration catalyst of the catalyst module whose low-temperature SCR denitration catalyst has been deactivated to obtain a regenerated powder within a desired size range.

[0036] According to one embodiment, the low-temperature SCR denitration catalyst of the catalyst module whose low-temperature SCR denitration catalyst has been deactivated is cleaned before or after the crushing.

[0037] According to one embodiment, a screening treatment is performed after the crushing.

[0038] According to one embodiment, at least one of a thermoplastic plastic powder and a low-temperature SCR denitration catalytically active component powder is added to the regenerated powder.

[0039] According to one embodiment, the added thermoplastic plastic powder and low-temperature SCR denitration catalytically active component powder is below 30% by weight of the regenerated powder.

[0040] According to one embodiment, the added thermoplastic plastic powder and low-temperature SCR denitration catalytically active component powder is below 10% by weight of the regenerated powder.

[0041] According to one embodiment, at least one of a pore-forming agent, a foaming agent and a plasticizer is added to the regenerated powder.

[0042] According to an embodiment, the re-shaping of the regenerated powder is selected from at least one of the following processes: thermoforming, hot press forming, extrusion forming, 3D printing forming, electrospinning forming, spray forming, injection molding, die molding, blow molding, calendering, rotational molding, suction molding, slush molding, casting, foaming, transfer molding and winding molding.

[0043] According to an embodiment, the re-shaping process of the regenerated powder is the same as the shaping process of the powder of the low-temperature SCR De-NOx catalyst before regeneration.

[0044] According to an embodiment, the final shape of the regenerated low-temperature SCR De-NOx catalyst is selected from at least one of the following: flat plate, corrugated plate, honeycomb, granular, cloth, tube, rod, mesh and porous sponge.

[0045] According to an embodiment, the catalyst module is a segmented catalyst module comprising a plurality of catalyst module segments, and the recycling method comprises replacing the deactivated catalyst module segment in the reactor with a brand new catalyst module segment or a regenerated catalyst module segment.

[0046] According to an embodiment, the final shape of the re-shaping of the regenerated powder is the same as the shape of the low-temperature SCR De-NOx catalyst before regeneration.

[0047] According to the concept of another aspect of the present application, there is provided a fine SCR De-NOx catalyst system capable of re-shaping and multiple regeneration, comprising: a catalyst module configured to be adapted for replacement, containing a regenerated low-temperature SCR De-NOx catalyst, wherein the working temperature of the low-temperature SCR catalyst is below 300°C; a reactor for accommodating the catalyst module; a spray system for spraying a reducing agent into the reactor, wherein the regenerated low-temperature SCR De-NOx catalyst comprises: a carrier skeleton formed of a thermoplastic plastic; and a low-temperature SCR De-NOx catalytically active component compounded in and supported by the carrier skeleton; the fine SCR De-NOx catalyst system is configured to facilitate the removal of the deactivated catalyst module and the replacement of a new catalyst module and / or a regenerated catalyst module; wherein the regenerated catalyst module is a catalyst module obtained by regenerating and reloading the regenerated low-temperature SCR De-NOx catalyst after being taken out of the deactivated catalyst module; and the regenerated low-temperature SCR De-NOx catalyst is capable of being regenerated by re-shaping of the carrier skeleton of the thermoplastic plastic.

[0048] According to an embodiment, a plurality of the catalyst modules are arranged inside the reactor spaced apart from each other. The shape of the carrier skeleton can be selected from at least one of a flat plate, a corrugated plate, a honeycomb, a granule, a cloth, a tube, a rod, a mesh, and a porous sponge. The carrier skeleton can have a porous structure.

[0049] The thermoplastic can be selected from at least one of PEEK, PFA, PPS, PTFE, PBT, PEI, PES, PCTFE, ETFE, PAI, PBI, PI, FEP, PPA, PSU, PPSU, PE, PP, fluoro rubber (FKM), silicone rubber (VMQ), and nylon (PA).

[0050] According to an embodiment, the carrier skeleton has a self-supporting configuration both before and after the reshaping, whereby the regenerable low-temperature SCR denitration catalyst has a self-supporting configuration without external support.

[0051] According to an embodiment, the reactor is configured with at least one of a homogenizer, a pressure equalization device, a flue gas temperature regulator, a temperature sensor, and a pressure sensor.

[0052] According to an embodiment, the injection system comprises a reducing agent injection system for injecting a reducing agent or a reducing agent solution into the reactor; and a reducing agent supply and storage system for storing and delivering the reducing agent to the injection system.

[0053] According to an embodiment, the low-temperature SCR catalyst has an operating temperature below 250°C.

[0054] The catalyst module can be a segmented catalyst module comprising a plurality of catalyst module segments spaced apart from each other.

[0055] The plurality of catalyst module segments can comprise at least two of a plate catalyst module segment, a honeycomb catalyst module segment, and a granule catalyst module segment, preferably all three.

[0056] According to an embodiment, the segmented catalyst module arranges the plate catalyst module segment, the honeycomb catalyst module segment, and the granule catalyst module segment in this order along the flue gas flow direction. In this order, as the flue gas flows through the plate catalyst module segment, the honeycomb catalyst module segment, and the granule catalyst module segment in this order, due to the internal configurations of these three catalyst module segments, naturally, the space velocity of the flue gas will decrease in this order, thereby effectively removing, in this order, step by step, the nitrogen oxides (NO x ) in the flue gas according to these three catalyst module segments, reducing the content of NO x , and achieving fine denitration in segments.

[0057] According to an embodiment, further comprising a control system for monitoring and / or adjusting the reaction conditions of the fine SCR De-NOx catalyst system.

[0058] According to an embodiment, the reshaped shape of the carrier skeleton is selected from at least one of flat plate, corrugated plate, honeycomb, granular, cloth, tube, rod, mesh, and porous sponge.

[0059] According to an embodiment, the low-temperature SCR De-NOx catalytically active component comprises at least one of Mn / Ce-based catalytic material, V-based catalytic material, or Cu-based catalytic material.

[0060] According to an embodiment, the carrier skeleton has an internal porous structure.

[0061] According to an embodiment, the internal porous structure accounts for more than 10% of the volume percentage of the carrier skeleton.

[0062] According to an embodiment, the reshaping is thermoplastic molding.

[0063] According to an embodiment, the thermoplastic suitable for thermoplastic molding is selected from at least one of PEEK, PFA, PPS, PTFE, PBT, PEI, PES, PCTFE, ETFE, PAI, PBI, PI, FEP, PPA, PSU, PPSU, PE, PP, fluoro rubber (FKM), silicone rubber (VMQ), and nylon (PA).

[0064] According to an embodiment, the carrier skeleton has a self-supporting configuration before and after the reshaping, thereby making the regenerable low-temperature SCR De-NOx catalyst have a self-supporting configuration without external support.

[0065] According to an embodiment, a plurality of layers of the catalyst modules are arranged inside the reactor and spaced apart from each other.

[0066] According to an embodiment, the low-temperature SCR catalyst can comprise a pore-forming agent and / or a foaming agent for forming an internal porous structure.

[0067] According to an embodiment, the internal porous structure accounts for more than 10% of the volume percentage of the carrier skeleton of the low-temperature SCR catalyst.

[0068] According to an embodiment, the low-temperature SCR catalyst active part comprises a low-temperature De-NOx catalytically active substance.

[0069] According to an embodiment, the low-temperature denitration catalytically active substance comprises at least one of Mn / Ce-based catalytic material, V-based catalytic material or Cu-based catalytic material. According to an embodiment, the low-temperature SCR catalytic active part is compounded in the form of dispersed particles in the carrier skeleton. According to an embodiment, the low-temperature SCR catalytic active part is compounded in the form of a thin film coated on the carrier skeleton. According to an embodiment, the working temperature of the low-temperature SCR catalyst is below 300°C.

[0070] According to an embodiment, the carrier skeleton of the low-temperature SCR catalyst has a self-supporting configuration before reshaping and after reshaping, thereby making the low-temperature SCR catalyst have a self-supporting configuration without external support in the set working temperature range.

[0071] The application also discloses the low-temperature SCR catalytic denitration use of the above-mentioned fine SCR denitration catalyst system capable of being reshaped and regenerated in the flue gas denitration of thermal power plants, incineration plants, cement plants and gas washing equipment or the exhaust gas treatment of internal combustion engine driven motor vehicles.

[0072] The application also discloses a low-temperature SCR catalyst capable of being reshaped and regenerated for the above-mentioned fine SCR denitration catalyst system, the low-temperature SCR catalyst comprising: a carrier skeleton of thermoplastic plastic, wherein the shape of the carrier skeleton of thermoplastic plastic is selected from at least one of flat plate, corrugated plate, honeycomb, granular, cloth, tubular, rod, mesh and porous sponge; a low-temperature SCR catalytic active part compounded on or in the carrier skeleton and supported thereby; the low-temperature SCR catalyst can be regenerated by reshaping the carrier skeleton of thermoplastic plastic into one of the following shapes: flat plate, corrugated plate, honeycomb, granular, cloth, tubular, rod, mesh and porous sponge. According to an embodiment, the low-temperature SCR catalytic active part comprises a low-temperature denitration catalytically active substance.

[0073] According to an embodiment, the low-temperature denitration catalytically active substance comprises at least one of Mn / Ce catalytic material, V-based catalytic material or Cu-based catalytic material. According to an embodiment, the carrier skeleton has an internal porous structure. According to an embodiment, the internal porous structure accounts for more than 10% of the volume percentage of the carrier skeleton. According to an embodiment, the low-temperature SCR catalytic active part is compounded in the form of dispersed particles in the carrier skeleton. According to an embodiment, the low-temperature SCR catalytic active part is compounded in the form of a thin film coated on the carrier skeleton. According to an embodiment, the working temperature of the low-temperature SCR catalyst is below 300°C. According to an embodiment, the carrier skeleton of the low-temperature SCR catalyst has a self-supporting configuration before reshaping and after reshaping, thereby making the low-temperature SCR catalyst have a self-supporting configuration without external support in the set working temperature range.

[0074] This application overcomes many technical defects of traditional technologies, including: overcoming the huge waste and high cost of traditional catalysts / modules caused by easy deactivation, inability to be reshaped and regenerated; the negative environmental impact and pollution caused by the disposal of traditional catalysts / modules; overcoming the lengthy, complex and costly process steps of traditional catalysts / modules; the lightweight catalyst module brought about by the inherent nature of the support material replaces the bulkiness of traditional catalysts, reducing the difficulty of disassembly, assembly and transportation of traditional catalysts / modules; and the fact that traditional catalyst systems cannot perform fine denitrification and cannot / are not easy to replace, update or regenerate, etc. Attached Figure Description

[0075] The above-described features and advantages of these embodiments, as well as other features and advantages, and the ways in which they are implemented, will become more apparent from the following description in conjunction with the accompanying drawings, and embodiments of this application can be better understood.

[0076] Figure 1A and Figure 1B These are, respectively, honeycomb catalyst products and granular catalyst products prepared by thermoplastic molding according to an embodiment of this application.

[0077] Figure 2A and Figure 2B These are three-dimensional schematic diagrams of industrial products of plastic honeycomb catalysts prepared by thermoplastic molding, for example, according to an embodiment of this application. Figure 2A ), and cross-sectional schematic diagram ( Figure 2B ),in Figure 2B The diagram schematically illustrates the presence of numerous pore structures in the flue gas channels of this thermoplastic honeycomb catalyst product.

[0078] Figure 3A A front view photograph of a plate-shaped catalyst product prepared by hot pressing according to an embodiment of this application is shown.

[0079] Figure 3B A perspective view of a thermoplastic plate catalyst product prepared by hot pressing according to an embodiment of this application is schematically shown.

[0080] Figure 3C schematically shown Figure 3A The image shown is an enlarged schematic of a single thermoplastic plate catalyst product, demonstrating the presence of numerous porous structures on the surface of the plate catalyst.

[0081] Figure 4 A schematic diagram of an activity evaluation apparatus for testing and evaluating the catalytic activity of the honeycomb low-temperature SCR catalyst of this application is shown.

[0082] Figure 5Performance comparison of PEEK based catalysts prepared by thermoforming process according to an embodiment of the present application with commercial catalysts is schematically shown.

[0083] Figure 6 Performance comparison of PEEK, PFA and PPS based catalysts prepared by thermoforming process according to an embodiment of the present application with commercial catalysts is schematically shown.

[0084] Figure 7 Performance comparison of different plastic based catalysts prepared by hot pressing process according to an embodiment of the present application is schematically shown.

[0085] Figure 8 SO2 poisoning performance test of PEEK based catalyst according to an embodiment of the present application and the results of SO2 poisoning performance test of PEEK based catalyst after re-shaping after deactivation by use are schematically shown.

[0086] Figure 9 Data of performance recovery of PEEK based catalyst after SO2 poisoning and regeneration according to an embodiment of the present application is schematically shown.

[0087] Figure 10 Performance test results of PEEK based catalyst after multiple re-shaping of PEEK based catalyst according to an embodiment of the present application at predetermined reasonable working temperature are schematically shown.

[0088] Figure 11 Thermoforming process example of thermoforming process for preparing low temperature SCR catalysts of the present application according to an embodiment of the present application is schematically shown.

[0089] Figure 12 Example of multiple regeneration capable fine SCR De-NOx catalyst system according to an embodiment of the present application is schematically shown for schematically showing and describing the system of segmented catalyst (module / segment) arrangement of the present application for fine SCR De-NOx and its general configuration. DETAILED DESCRIPTION

[0090] The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the application will be apparent from the description and drawings, and from the claims.

[0091] Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising" or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

[0092] The application will be described in greater detail below with reference to a number of specific embodiments of the application.

[0093] Generally speaking, the working principle of selective catalytic reduction (SCR) De-NOx catalyst mainly involves the following steps:

[0094] (i) External diffusion process: the process of diffusion of nitrogen oxides and ammonia from the gas phase bulk to the outer surface of the catalyst;

[0095] (ii) Internal diffusion process: diffusion of the reactants from the outer surface to the inner surface of the catalyst, and reaction at the active center;

[0096] (iii) Adsorption process: adsorption of the reactants at the active center;

[0097] (iv) Catalytic reaction: catalytic reduction reaction of adsorbed nitrogen oxides (NO x ) and ammonia at the active center of the catalyst and at a certain temperature, to generate nitrogen and water;

[0098] (v) Desorption process: desorption of the reaction products from the active center; and

[0099] (vi) Internal diffusion process: diffusion of the reaction products from the active center to the outer surface through the inner surface of the catalyst after desorption.

[0100] Low-temperature SCR De-NOx systems generally include a device for storing and injecting a reducing agent (such as ammonia NH3 or urea CO(NH2)2), an SCR control unit, and an SCR catalyst. Urea is hydrolyzed and decomposed to generate ammonia. At a suitable low-temperature condition (generally about 200-300°C or below), the ammonia-selective catalytic reduction (NH3-SCR) agent can directly catalyze the reaction of nitrogen oxides (NO x ) in flue gas with ammonia to generate harmless nitrogen and water, while also absorbing harmful flue gas particles. The corresponding reaction formula is as follows:

[0101] CO(NH2)2+ H2O = CO2↑+ 2NH2↑

[0102] 4NH3+ 4NO + O2 = > 4N2+ 6H2O

[0103] 4NH3+ 2NO2+ O2 = > 3N2+ 6H2O

[0104] In terms of conventional technology, TiO2-based catalysts gradually replace Pt-Rh and Pt series catalysts. The composition of such catalysts has V2O5 as the main active component and WO3, MoO3 as the anti-oxidation and anti-poisoning auxiliary components, for example, mainly composed of V2O5(WO3), Fe2O3, CuO, CrO x , MnO xMetal oxides such as TiO2, Al2O3, ZrO2, SiO2, activated carbon (AC), etc. or a mixture thereof as a carrier, and a reducing agent such as liquid ammonia or urea in the SCR system to form a reducing reaction, which is the mainstream catalyst product for the SCR denitration project in power plants.

[0105] The inventors of the present application found that in the field of catalysts, polymer-supported nanocatalyst particles as carrier materials can be regenerated and reused, which makes it possible for the nanocatalyst particles after service to be regenerated and reused in new or regenerated catalysts. This recyclable feature makes it possible for the pollutants generated during the production of catalysts not to flow back into the environment to cause pollution. The organic polymer carrier (or base, skeleton, etc.) of the catalyst has a relatively low degree of active site exposure due to its small surface area, and therefore needs to add other aids to help generate a large number of pore structures to increase its specific surface area. In addition, this method accelerates the diffusion of water out of the catalyst, which helps to improve the activity and long-term stability of the catalyst.

[0106] One of the main ideas of the present application is to use a hydrophobic organic polymer, especially a hydrophobic thermoplastic, as the carrier skeleton of a low-temperature SCR catalyst. On the one hand, it can achieve the above technical advantages and be technically applicable to the application of low-temperature SCR catalysts (here, "low temperature" refers to the normal working temperature of the SCR catalyst, which is generally below 300°C, and more preferably below 250°C). On the other hand, the thermoplasticity of such plastics makes it possible to scale the reforming and regeneration process of the low-temperature SCR catalyst.

[0107] Of course, those skilled in the art can understand that using thermoplastic plastics (such as but not limited to PPS, PEEK, PBT, etc.) as low-temperature SCR catalyst carrier / base materials can achieve more technical advantages and benefits, including but not limited to: easy cleaning, crushing, processing and reforming after sulfur (e.g., SO2) poisoning and deactivation (ammonium sulfate deposition); can be easily used in a wide range of application environments including low ash areas, and is easy to clean and regenerate; the characteristics of thermoplastic plastics make the low-temperature SCR catalyst product lightweight, easy to transport and install, and less brittle, which is not easy to damage during transportation, installation and use; wide availability, easy availability and low cost of materials; non-toxicity and environmental friendliness of materials; extremely high yield (theoretical yield 100%, no inferior products); extremely high recycling rate (theoretical recycling rate close to 100%).

[0108] The inventors of the present application have found that the carrier / base material suitable for low-temperature SCR catalysts can be selected to use a thermoplastic plastic material with relatively high plasticizing forming temperature (e.g. its forming temperature is generally above about 200℃) as the carrier skeleton forming agent, such as but not limited to PBI; PI; TPI; PAI; PEEK; PPS; PTFE; PFA; ETFE; PCTFE, etc. The normal working temperature of such thermoplastic plastic-based “low-temperature” SCR catalyst is generally below 300℃, more preferably below 250℃.

[0109] The forming process of thermoplastic plastic material in the preparation of low-temperature SCR catalysts of the present application can include but is not limited to: thermoforming, hot-press forming, extrusion forming, 3D printing forming, electrostatic spinning forming, spray forming, injection forming, die forming, blow forming, calendering forming, rotational molding forming, vacuum forming (suction forming), casting forming (injection forming), slush molding forming, flow casting forming, foaming forming, transfer molding forming (compression molding), winding forming, etc.

[0110] The shape (configuration) of the low-temperature SCR catalysts of the present application after preparation can include but is not limited to: honeycomb catalyst products, plate catalyst products, corrugated plate catalyst products, tubular catalyst products, rod catalyst products, granular catalyst products, mesh catalyst products, porous solid foam catalyst products, etc. According to the above concepts and features of the present application, these catalyst products can be reformed and regenerated after use.

[0111] According to the concept of one aspect of the present application, the thermoplastic forming of the low-temperature SCR catalysts of the present application can effectively perform rapid thermoplastic forming using polymeric thermoplastic as the carrier material of the catalyst; the combination effect is better after adding catalyst powder (which can act as a binder), and the forming effect is better; the large number of pore structures generated during the thermoplastic process can make the formed catalyst have a larger specific surface area, thereby improving the catalytic activity; the performance of the catalyst is directly related to the content of the catalyst during the forming process, and the thermoplastic formed low-temperature SCR catalysts of the present application have a larger proportion of catalyst components, so their catalytic performance is better than existing catalysts under the same test conditions.

[0112] The thermoplastic polymer materials suitable for the low-temperature SCR catalysts of the present application in thermoplastic forming and extrusion forming include: PEEK, PFA, PPS, PTFE, PBT, PEI, PES, PCTFE, ETFE, PAI, PBI, PI, FEP, PPA, PSU, PPSU, PE, PP, fluororubber (FKM), silicone rubber (VMQ), nylon (PA), etc. These materials are all polymer materials with rapid thermoplastic ability and stable physical and chemical properties.

[0113] In the present embodiment, the catalyst powder used is selected from catalyst materials having good low-temperature denitration performance, such as: Mn / Ce low-temperature denitration catalyst, V-based catalyst, Cu-based catalyst, and the like.

[0114] For detailed introduction of the Mn / Ce low-temperature denitration catalyst and related content of the formula, reference can be made to the Chinese patent application for invention CN117019136A filed by the inventor of the present application on July 28, 2023, which is incorporated herein by reference.

[0115] Examples of low-temperature SCR catalysts

[0116] Figure 1A and Figure 1B and Figure 2A and Figure 2B The thermoplastic forming method of the present application is schematically illustrated in the catalyst products prepared by the thermoplastic forming method. Among them, Figure 1A and Figure 1B are respectively a honeycomb catalyst product and a granular catalyst product prepared by the thermoplastic forming method according to an embodiment of the present application. Figure 2A and Figure 2B are respectively a perspective view ( Figure 2A ) and a cross-sectional view ( Figure 2B ) of a plastic honeycomb catalyst industrial product prepared by the thermoplastic forming method according to an embodiment of the present application, wherein Figure 2B schematically illustrates that there are a large number of pore structures in the flue gas channel of the thermoplastic honeycomb catalyst product, which are formed by the added pore-forming agent. Those skilled in the art can understand that, as mentioned above, the preparation of the low-temperature SCR catalyst (including but not limited to honeycomb) mentioned in the present application can also be implemented by other forming processes disclosed in the present application, and is not limited to thermoplastic forming.

[0117] Thermo-plastic forming of low-temperature SCR catalysts

[0118] Figure 11 schematically illustrates an example of the thermoplastic forming process for preparing the low-temperature SCR catalyst of the present application according to an embodiment of the present application.

[0119] Hereinafter, taking PEEK material as an example, the thermoplastic forming process of the low-temperature SCR catalyst of the present application is further introduced in combination with the accompanying Figure 11 schematically illustrates the thermoplastic forming process of the low-temperature SCR catalyst of the present application.

[0120] 1) Mix 200-mesh Mn / Ce catalyst powder (8 parts by weight) with PEEK powder (20 parts by weight), add NaCl, CaSO4, (NH4)2CO3, carbon powder, etc. as pore-forming agents (10 parts by weight), mix thoroughly, and then place in a cylindrical stainless steel mold.

[0121] 2) Seal the stainless steel mold with stainless steel press, put into the muffle furnace to heat up, plasticized forming at 300-320℃, about 10.0MPa pressure for 6 hours.

[0122] 3) After water cooling, soak for 1-24 hours to remove the pore-forming agent, dry to obtain a cake-shaped thermoplastic formed catalyst, and then carry out punching processing on the obtained catalyst on a numerical control machine tool to obtain a honeycomb-shaped low-temperature SCR catalyst product, for example Figure 1A and Figure 2A and Figure 2B as shown.

[0123] Thermo-compression formed low-temperature SCR catalysts

[0124] Figure 3A A front view of a plate-type catalyst product prepared by a hot-pressing forming method according to an embodiment of the present application is shown. Figure 3B A perspective view schematically showing a thermoplastic plate-type catalyst product prepared by a hot-pressing forming method according to an embodiment of the present application is shown. Figure 3C A photo of a single thermoplastic plate-type catalyst of the thermoplastic plate-type catalyst product shown in Figure 3A shows that a large number of pore structures exist on the surface of the plate-type catalyst.

[0125] The thermoplastic polymer materials suitable for use in the hot-pressing forming of the low-temperature SCR catalyst of the present application include ETFE, PFA, FEP, PPS, PBT, PBI, PEI, PSU, PEEK, fluororubber (FKM), silicone rubber (VMQ), nylon (PA), etc. These polymer materials are all materials having a suitable softening temperature, almost no flow in the molten state, good surface wettability, and stable physical and chemical properties.

[0126] Regeneration of low-temperature SCR catalysts

[0127] An important inventive concept and key advantage of the present application is that the low-temperature SCR catalyst of the present application can be conveniently regenerated by a re-forming process.

[0128] The process method for regenerating the low-temperature SCR catalyst of the present application is further introduced below by taking the PEEK-based low-temperature SCR catalyst of the present application as an example.

[0129] 1) The deactivated (for example, deactivated due to sulfur poisoning) PEEK-based thermoplastic formed catalyst is optionally cleaned first, for example, the surface fly ash and ammonium sulfate deposits are washed away by ultrasonic cleaning, and after drying, the catalyst is put into a clean crusher for crushing treatment, for example, after crushing processing, the regenerated powder for re-forming is obtained after passing through a 10-mesh sieve.

[0130] 2) Add a suitable proportion of a pore-forming agent (see previous examples) to the regenerated powder and mix thoroughly before placing in a mould.

[0131] The pore-forming agent can be, for example, NaCl, CaSO4, (NH4)2CO3, carbon powder, etc., and can be added in a proportion of, for example, 10% to 150% by weight of the regenerated powder. An example of a suitable proportion of NaCl is, for example, between 50% and 120% by weight of the regenerated powder.

[0132] 3) The mixed powder is then placed in a cylindrical mould, the mould is sealed with a press and placed in a muffle furnace to heat and perform hot plastic forming. The heating temperature is 300-320°C, the pressure is 1-5 MPa, and the hot plastic forming is performed for 2-12 hours. If the particles of the regenerated powder are larger, the forming time of the remoulding process can be appropriately extended.

[0133] 4) After hot plastic forming, the mould is cooled with water / air, and the catalyst is removed from the mould when it has cooled to room temperature. The catalyst is then again cooled with water, and is removed and transferred to a cleaning solution to wash away the pore-forming agent. The soaking time in the cleaning solution is 1-12 hours, and the cleaning solution can be one or more of ammonia, sodium bicarbonate, ammonium carbonate, and trisodium phosphate, and the pH of the solution can be maintained at 5-8. After this, the low-temperature SCR catalyst in honeycomb form is obtained by punching on a numerical control machine tool.

[0134] In this regard, those skilled in the art will understand that, in the above process step 1), a certain proportion of catalyst powder (for example, 10% of Mn / Ce-based catalyst powder) and / or PEEK powder can be optionally added to the above regenerated powder to make up for possible losses in composition and performance. Of course, this is not essential, and test studies have shown that the low-temperature SCR catalyst of the present application can still be successfully remoulded and regenerated without substantially affecting its catalytic performance, without adding catalyst and / or polymer powder. Experimental data show that the denitration efficiency of the low-temperature SCR catalyst of the present application after regeneration is comparable to that of existing industrial catalysts, and its activity can be maintained at at least 80% of the activity of the original catalyst.

[0135] Those skilled in the art will understand that the above low-temperature SCR catalyst in honeycomb form can be remoulded into other shapes as required, for example, a low-temperature SCR catalyst in the form of a rod or a pellet, etc., and it is not necessary to remould it into a low-temperature SCR catalyst in honeycomb form.

[0136] In this regard, it is appreciated by those skilled in the art that in the above process step 1), a certain percentage of catalyst powder (e.g. 10% of Mn / Ce powder) and / or PEEK powder can be optionally replenished in the above regenerated powder to make up for possible loss of ingredients and performance. Of course, this is not necessary, and test studies have shown that the low-temperature SCR catalyst of the present application can still be successfully reshaped and regenerated without substantially affecting its catalytic performance, without replenishing catalyst and / or polymer powder. Experimental data show that the low-temperature SCR catalyst of the present application has a denitration efficiency after regeneration that is comparable to that of existing industrial catalysts, and its activity can be maintained at least 80% or more, as described in detail below.

[0137] It is appreciated by those skilled in the art that the above honeycomb-shaped low-temperature SCR catalyst can be reshaped into other shapes as needed during reshaping and regeneration, such as rod-shaped, pellet-shaped low-temperature SCR catalyst, etc., and does not necessarily have to be reshaped into a honeycomb-shaped low-temperature SCR catalyst.

[0138] It is also appreciated by those skilled in the art that the above reshaping and regeneration of the low-temperature SCR catalyst can also be performed using other suitable and applicable process methods other than thermoplastic molding and hot-press molding, such as but not limited to: hot extrusion molding, 3D printing molding, electrospinning molding, spray molding, cold extrusion molding, die molding, blow molding, calender molding, rotational molding, vacuum molding (blister molding), casting molding (injection molding), slush molding, flow molding, foaming molding, press injection molding, winding molding, etc., which can be determined according to the material type of the thermoplastic plastic skeleton, the catalyst active ingredients and parameters, the shape of the low-temperature SCR catalyst required, the needs of the application, etc.

[0139] Fine SCR DeNOx catalyst system regenerable multiple times and its operation

[0140] Figure 12 An example of a regenerable fine SCR denitration catalyst system according to an embodiment of the present application is schematically shown, for illustratively showing and describing the system of the segmented catalyst (module / segment) arrangement of the present application for fine SCR denitration and its general configuration.

[0141] According to the present embodiment, a low-temperature selective catalytic reduction (SCR) system for flue gas denitration is introduced, which includes the low-temperature SCR catalyst of the present application, such as a catalyst module prepared using thermoplastic molding and extrusion molding processes.

[0142] The fine SCR denitration catalyst system of the present application has better performance in the molding process, catalytic activity and mechanical strength of the low-temperature SCR catalyst, such as providing higher catalytic activity and better mechanical strength.

[0143] In this embodiment, the fine SCR DeNOx catalyst system can be composed of several main parts:

[0144] (1) Replaceable catalyst modules: can include several (such as multiple layers) of the regenerable low-temperature SCR DeNOx catalyst products of the present application, such as plate, honeycomb and / or granular catalysts spaced apart from each other, for providing a staged / tiered low-temperature SCR DeNOx process, such as below 300°C.

[0145] Preferably, as introduced earlier, the regenerable low-temperature SCR DeNOx catalyst can include: a carrier skeleton formed of thermoplastic plastic; a low-temperature SCR DeNOx catalytically active component compounded in and supported by the carrier skeleton. The fine SCR DeNOx catalyst system is configured to facilitate the removal of the deactivated catalyst modules and replacement with new catalyst modules and / or regenerated catalyst modules, which are catalyst modules obtained by regenerating and reloading back into the deactivated catalyst modules after the removal of the regenerable low-temperature SCR DeNOx catalyst from the deactivated catalyst modules, which is capable of being regenerated by reshaping the carrier skeleton of thermoplastic plastic.

[0146] For example, the plurality of catalyst module segments includes at least two of a plate catalyst module segment, a honeycomb catalyst module segment and a granular catalyst module segment.

[0147] According to a preferred example, the staged catalyst modules are arranged in the order of a plate catalyst module segment, a honeycomb catalyst module segment and a granular catalyst module segment along the direction of the flue gas flow. In this order, as the flue gas flows through the plate catalyst module segment, the honeycomb catalyst module segment and the granular catalyst module segment in sequence, due to the internal structure of these three catalyst module segments, naturally, the flow rate of the flue gas will sequentially decrease in this order, thereby sequentially, progressively and effectively removing, in accordance with these three catalyst module segments, the nitrogen oxides (NO x ) in the flue gas, reducing the NO x content, and achieving fine DeNOx in stages.

[0148] (2) Reactor: for housing the catalyst modules and providing a suitable SCR DeNOx reaction environment.

[0149] The reactor can be generally made of stainless steel (e.g., 316L or 304) or carbon steel (coated with high-temperature resistant anticorrosive coating) and have a cylindrical or cuboid shape with a size designed according to the flue gas treatment capacity (e.g., 2-5 meters in diameter and 5-15 meters in length). The reactor can be provided with multiple layers of catalyst modules (e.g., arranged in sequence according to the flow direction of the flue gas, such as a plate catalyst module, a honeycomb catalyst module, and a granular catalyst) to optimize the gas flow distribution and reaction efficiency. The thickness of each layer of catalyst can be 300-500 mm or more, and the spacing between layers can be 50-100 mm. A homogenizer (e.g., a flow guide plate or a static mixer) can be arranged at the inlet of the reactor to ensure uniform mixing of the flue gas and ammonia. A pressure balancing device can be arranged at the outlet of the reactor to avoid gas flow disturbance.

[0150] The reactor can be equipped with a flue gas temperature adjustment system (e.g., a heat exchanger or a heater) to maintain the reaction temperature within a range of, for example, 200-300°C, to meet the requirements of low-temperature SCR catalysts.

[0151] The reactor can be provided with temperature sensors (e.g., thermocouples or infrared thermometers) and pressure sensors to monitor the operating state in real time and automatically adjust through a control system.

[0152] For example, commercially available reactors include the SCR-EE-LA / UR reactor produced by Hebei Chengyue Environmental Engineering Co., Ltd., which supports low-temperature denitrification and is suitable for boiler flue gas treatment due to its modular design; the double-path vertically arranged reactor produced by Shandong Shoufeng Intelligent Environmental Protection Equipment Co., Ltd., which is suitable for various dust flue gas conditions; the honeycomb catalyst integrated reactor provided by Yuanchen Environmental Protection Technology Co., Ltd., and the like.

[0153] (3) Injection system: used for injecting a reducing agent (e.g., ammonia water or urea solution) into the reactor.

[0154] The injection system can generally include:

[0155] An ammonia / ammonia water injection system can use stainless steel (e.g., 316L) or ceramic nozzles and can have a multi-hole atomizing type or a fan-shaped injection type with a hole diameter of 0.5-2 mm and an adjustable injection angle of 30-90° to ensure sufficient mixing of ammonia and flue gas. The nozzles can be uniformly distributed along the cross section of the flue duct with a spacing of, for example, 200-500 mm and arranged in a counterflow or co-flow direction with respect to the flue gas flow direction to enhance the mixing effect. The injection pressure and flow rate of ammonia / ammonia water can be 0.3-0.8 MPa and 50-500 L / min (which can be adjusted according to the NOx concentration of the flue gas), respectively. x The concentration of the reducing agent can be dynamically adjusted.

[0156] An ammonia supply and storage system can include a storage tank and a delivery device. The storage tank can have a volume of 10-50 m 3A stainless steel storage tank with a design pressure of 1.5 MPa, equipped with a liquid level gauge, a safety valve, and a leakage detection device. The delivery device may, for example, be a corrosion-resistant centrifugal pump (such as the Grundfos CR series) or a screw pump with a flow accuracy of ±2% and PLC remote control support.

[0157] Examples of commercially available injection systems include the SNCR-EE-LA / UR type provided by Hebei Chengyue Environmental Engineering Co., Ltd., equipped with high-pressure atomizing nozzles and a redundant safety system, and the "double-path ammonia injection system" (suitable for high-dust flue gas) from Shandong Shoufeng Intelligent Environmental Protection Equipment Co., Ltd., which can be integrated with a steam carrier gas device to enhance penetration.

[0158] (4) Optional control system: for monitoring and / or adjusting SCR reaction conditions such as temperature, pressure, and reducing agent injection amount, etc.

[0159] The control system can be either a component of the fine SCR denitration catalyst system or integrated into the control system of the application site or equipment of the fine SCR denitration catalyst system, such as a factory, a workshop, a waste gas treatment section, a ship, a car, etc.

[0160] As an example, the control system can be an automation system based on PLC (such as Siemens S7-1200), integrated with an ammonia flow meter (such as a mass flow meter), a NO x concentration sensor (such as an ultraviolet analyzer), and a temperature feedback module to achieve closed-loop control of the ammonia-nitrogen molar ratio (NH3 / NO x ) (target value 0.8-1.2). In the event of an emergency, an ammonia shut-off valve (such as an ASCO solenoid valve) can be triggered with a response time <1 second.

[0161] In this embodiment, the general operation of the fine SCR denitration catalyst system is as follows:

[0162] (1) System startup: After the system is started, the control system can automatically or manually adjust the reaction condition parameters in the reactor, such as reaction temperature, pressure, reducing agent injection amount, etc., according to the flue gas conditions.

[0163] (2) SCR catalytic denitration reaction: The injection system injects reducing agent into the reactor, which reacts with NO x in the flue gas on the surface of the low-temperature SCR catalyst to generate nitrogen and water.

[0164] (3) Monitoring and adjustment: The control system monitors the reaction efficiency in real time and adjusts the reaction conditions such as reaction temperature, pressure, reducing agent injection amount, and / or reaction time as needed.

[0165] (4) Regeneration of the fine SCR DeNOx catalyst system: After a period of time, or a predetermined period of use, the low-temperature SCR DeNOx catalyst product is removed from the catalyst module, and the low-temperature SCR DeNOx catalyst is subjected to a pre-treatment prior to re-shaping and regeneration according to the regeneration method of the present application (e.g., the regeneration of the low-temperature SCR catalyst is described above), the regenerated low-temperature SCR catalyst is re-installed into the catalyst module, and the regeneration of the fine SCR DeNOx catalyst system is completed. Thus, the regenerated fine SCR DeNOx catalyst system can be re-used and used normally.

[0166] More specifically, according to an example, the re-use method of the fine SCR DeNOx catalyst system that can be regenerated multiple times can include the following steps: removing the catalyst module that has been deactivated from the reactor; pre-treating the low-temperature SCR DeNOx catalyst of the catalyst module that has been deactivated prior to regeneration; re-shaping the low-temperature SCR DeNOx catalyst after the pre-treatment, and simultaneously regenerating the low-temperature SCR DeNOx catalyst during the re-shaping; and loading the regenerated low-temperature SCR DeNOx catalyst into the catalyst module, and then re-installing the catalyst module into the reactor, thereby re-using the fine SCR DeNOx catalyst system.

[0167] The pre-treatment can include the following steps: crushing the low-temperature SCR DeNOx catalyst of the catalyst module that has been deactivated to obtain regenerated powder in a desired size range. The low-temperature SCR DeNOx catalyst of the catalyst module that has been deactivated can be washed before or after the crushing. A screening process can be performed after the crushing.

[0168] The fine SCR DeNOx catalyst system that can be regenerated according to the present embodiment uses the low-temperature SCR DeNOx catalyst that can be re-shaped and regenerated according to the present application, has a lower cost, a very simple and efficient re-shaping and regeneration process, a nearly 100% re-use rate, a nearly 100% regenerated catalytic activity, and a better mechanical strength than existing catalyst products, and can be effectively re-used to reduce NOx emissions in flue gas, reduce energy consumption, reduce pollution, reduce waste, re-shape and regenerate, have a low maintenance cost, have a light weight of the catalyst (module) and facilitate installation and transportation, etc., and meet strict environmental protection and regulatory requirements. x

[0169] Testing and evaluation of low-temperature SCR catalysts

[0170] Figure 4 A schematic diagram of an activity evaluation device for testing and evaluating the catalytic activity of the honeycomb low-temperature SCR catalyst according to the present application is schematically shown. Through the activity evaluation device, the catalytic activity of the low-temperature SCR catalyst, for example, MnO x ​The catalytic activity of the honeycomb-shaped low-temperature SCR catalyst of the application with CeO2 catalyst component was tested and evaluated, wherein the reaction gas can be mixed with the simulated flue gas in a gas mixing tank through a mass flow meter to control the gas flow, and after the catalytic reaction treatment of the low-temperature SCR catalyst of the application, the flue gas NOx can be tested at the tail gas end. x Content test.

[0171] Figure 5 The performance comparison of the PEEK catalyst (i.e., the PEEK-based low-temperature SCR catalyst of the application) prepared by the thermoforming method according to an embodiment of the application and the industrial catalyst is schematically shown. In the test, the test carrier gas is N2, the gas flow rate is 2.1 m / s, NO: 500 ppm, NH3: 500 ppm, O2: 5%, and the volume space velocity GHSV is 6000 h -1 The test results of the catalytic activity performance test of the PEEK catalyst, the industrial small-scale catalyst, and the industrial catalyst under the same size and the same test conditions are shown. The test results show that the low-temperature SCR catalyst prepared by using PEEK plastic as the carrier material has high catalytic activity and is close to the performance of the industrial catalyst.

[0172] Figure 6 The performance comparison of the PEEK, PFA, and PPS-based catalysts prepared by the thermoforming method according to an embodiment of the application and the industrial catalyst is schematically shown. In the test, the test carrier gas is N2, the gas flow rate is 2.1 m / s, NO: 500 ppm, NH3: 500 ppm, O2: 5%, and the volume space velocity GHSV is 6000 h -1 The test results of the performance test of the catalysts prepared by the thermoforming of different materials and the industrial catalyst under the same size and the same test conditions are shown. The content in the brackets after the material refers to the mass ratio of the catalyst active component in the carrier material. It can be seen that in the temperature range of 150℃ to 200℃, the catalytic performance of the formed catalyst prepared by using PEEK and PFA materials as the base material is almost the same as that of the industrial catalyst.

[0173] Figure 7 The performance comparison of different plastic-based catalysts prepared by the hot-pressing forming method according to an embodiment of the application is schematically shown. In the test, the test carrier gas is N2, the gas flow rate is 2.1 m / s, NO: 500 ppm, NH3: 500 ppm, O2: 5%, and the volume space velocity GHSV is 1500 h -1 The performance of the plate-shaped catalyst products of the application prepared according to three different catalyst skeleton materials is close to the performance of the industrial catalyst.

[0174] Figure 8The SO2 poisoning performance test results of the PEEK-based catalyst according to an embodiment of the present application and the PEEK-based catalyst after remolding after use are schematically shown. In the test, the test carrier gas is N2, the gas flow rate is 2.1 m / s, NO is 500 ppm, NH3 is 500 ppm, O2 is 5%, SO2 is 200 ppm, the gas hourly space velocity GHSV is 9000 h-1, and the temperature is 300°C. -1 In the comparative experiment, the running state of the shaped catalyst prepared by taking the PEEK material as an example at a higher SO2 concentration of 200 ppm is tested. The catalyst activity slightly decreases within 24 h but is stabilized at about 80% and does not change any more. After 24 h of the test, the catalyst is taken out, remolded, and the remolded catalyst is subjected to the same anti-poisoning experiment again. The results show that the catalyst performance is still maintained at more than 80% and does not decrease in the next 24 h of SO2 poisoning test. This shows that the remolding process does not affect the catalyst activity.

[0175] Figure 9 The data of the performance recovery of the PEEK-based catalyst after SO2 poisoning and regeneration according to an embodiment of the present application are schematically shown.

[0176] Figure 10 The performance test results of the PEEK-based catalyst after multiple remolding and working at a predetermined reasonable working temperature are schematically shown. A small amount of broken powder is inevitably lost in the remolding process, and therefore the catalyst powder or thermoplastic powder can be appropriately added in the remolding process, so that the size of the remolded catalyst and the size before breaking are basically consistent. Generally, the amount of addition is preferably less than about 30% of the total catalyst amount before breaking. Too much addition of the active component will cause the specific gravity of the thermoplastic material to be small, the adhesion between the active components to be weak, and the molding to be difficult.

[0177] Introduction of some technical effects of low-temperature SCR catalysts

[0178] In the technical content of the present application, the thermoplastic material can be used as the carrier (or matrix, skeleton, carrier skeleton, etc.) material of the catalyst, replacing the existing TiO2 and other conventional materials, thereby simplifying the integrated forming process of the catalyst and the regeneration process (for example, by reshaping) of the catalyst. Using the polymer thermoplastic as the carrier material and the catalyst powder as the inorganic binder of the thermoplastic, the two are tightly combined during the thermoplastic forming process, improving the overall mechanical strength of the catalyst and avoiding the leaching of the active components of the catalyst. The addition of the pore-forming agent enables the monolithic catalyst to have more fine pore structures during the preparation process, thereby improving the specific surface area of the catalyst. Using the thermoplastic as the base material enables the catalyst to be reused, and the regeneration process is simple and fast, which can avoid the energy waste and environmental pollution existing in the traditional regeneration process, and greatly prolongs the service life of the catalyst.

[0179] The experiments prove that the catalyst prepared by the preferred formula of the present application has similar denitration activity to the traditional industrial catalyst under the same size and test conditions at 200℃, 150℃, and 100℃. Under the preferred catalyst formula of the present application, the catalyst can maintain a performance of more than 80% without decline under 200ppm SO2 for long-term continuous operation. After cleaning and reshaping the poisoned catalyst by the regeneration method introduced in the present application, the catalyst activity at 200℃, 150℃, and 100℃ is basically the same as that before reshaping. After reshaping the catalyst multiple times by the regeneration method introduced in the present application, the catalyst activity at 200℃, 150℃, and 100℃ is basically the same as that before the first reshaping.

[0180] The foregoing description of several embodiments of the present application has been presented for the purpose of illustration. Many modifications and variations can be made to the teachings of the present application based on the above teachings. The scope and all equivalents of the present application are intended to be limited by the appended claims.

Claims

1. A method of recycling a regenerable fine SCR De-NOx catalyst system, the regenerable fine SCR De-NOx catalyst system comprising: a catalyst module comprising a regenerable low-temperature SCR denitration catalyst, wherein the low-temperature SCR catalyst has an operating temperature of 300°C or lower; a reactor for accommodating the catalyst module; and a spraying system for spraying a reducing agent into the reactor, characterized in that the regenerable low-temperature SCR denitration catalyst comprises a carrier skeleton formed of a thermoplastic plastic and a low-temperature SCR denitration catalytically active component compounded in and supported by the carrier skeleton, the recycling method comprises: removing the catalyst module that has been deactivated from the reactor; pre-treating the low-temperature SCR denitration catalyst of the catalyst module that has been deactivated before regeneration; re-molding the low-temperature SCR denitration catalyst after the pre-treatment, wherein the regeneration of the low-temperature SCR denitration catalyst is realized at the same time as the re-molding; and loading the regenerated low-temperature SCR denitration catalyst back into the catalyst module, and then re-loading the catalyst module back into the reactor, thereby realizing the recycling of the fine SCR denitration catalyst system.

2. The recycling method according to claim 1, characterized in that, the pre-treatment comprises the following step: crushing the low-temperature SCR denitration catalyst of the catalyst module that has been deactivated to obtain regenerated powder within a desired size range.

3. The recycling method according to claim 2, characterized in that, the low-temperature SCR denitration catalyst of the catalyst module that has been deactivated is cleaned before or after the crushing.

4. The recycling method according to claim 2, wherein, a screening process is performed after the crushing.

5. The recycling method according to claim 2, wherein, at least one of thermoplastic plastic powder and low-temperature SCR denitration catalytically active component powder is added to the regenerated powder.

6. The recycling method according to claim 5, wherein, the added thermoplastic plastic powder and low-temperature SCR denitration catalytically active component powder is below 30% by weight of the regenerated powder.

7. The recycling method according to claim 6, characterized in that, the added thermoplastic plastic powder and low-temperature SCR denitration catalytically active component powder is below 10% by weight of the regenerated powder.

8. The recycling method according to any one of claims 2-7, characterized in that, at least one of pore-forming agent, foaming agent and plasticizer can be added to the regenerated powder.

9. The recycling method according to any one of claims 2-8, characterized in that, the re-molding of the regenerated powder is selected from at least one of the following processes: thermoplastic molding, hot-press molding, extrusion molding, 3D printing molding, electrostatic spinning molding, spray molding, injection molding, die molding, blow molding, calender molding, rotational molding, suction molding, slush molding, casting molding, flow casting molding, foaming molding, transfer molding and winding molding.

10. The recycling method according to claim 9, characterized in that, the re-molding process of the regenerated powder is the same as the molding process of the powder of the low-temperature SCR denitration catalyst before regeneration.

11. The recycling method according to claim 10, characterized in that, the shape of the finished product of the re-molding of the regenerated powder is the same as the shape of the low-temperature SCR denitration catalyst before regeneration.

12. The recycling method according to any one of claims 1 to 11, characterized in that, the catalyst module is a segmented catalyst module comprising a plurality of catalyst module segments, and wherein the method further comprises replacing the catalyst module segment that has been deactivated in the reactor with a brand-new catalyst module segment or a regenerated catalyst module segment.

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