A low temperature scr catalyst capable of re-shaping and regeneration

Abstract

The present application relates to a low-temperature SCR catalyst capable of being reshaped and regenerated, comprising: a carrier skeleton of thermoplastic plastic, wherein the shape of the carrier skeleton of thermoplastic plastic is selected from at least one of the following: flat plate, corrugated plate, honeycomb, granular, cloth, tubular, rod, mesh and porous sponge; a low-temperature SCR catalyst active part integrally formed with and supported by the carrier skeleton; wherein 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.

Description

Technical Field

[0001] This application relates to the field of SCR catalyst technology, and particularly to nitrogen oxides (NOx). x Fine SCR denitrification catalysts, their structure, configuration and corresponding process methods.

[0002] More specifically, this application relates to a low-temperature SCR catalyst that can be reformulated and regenerated, applicable to a wide range of applications including but not limited to industrial flue gas denitrification, marine and automotive exhaust treatment, thermal power plants, incineration plants, cement plants, and gas scrubbing equipment. Background Technology

[0003] Nitrogen oxides (NO) x NOx is one of the most significant air pollutants. Excessive emissions not only seriously threaten human health but also cause a series of environmental problems. Currently, NOx emissions from non-power industries in my country... x The proportion of emissions is increasing year by year, and reducing flue gas emissions from non-power industries is a key focus of current air pollution prevention and control efforts.

[0004] Research and practice have found that ammonia-selective catalytic reduction (NH3-SCR) is currently the most effective method for controlling NO. x The most mature technology for emitting NO is also the one for controlling NO. x One of the best technologies for emissions control, and catalysts are the core of SCR technology.

[0005] Currently, the mainstream commercial SCR denitrification catalyst is a vanadium-based monolithic honeycomb catalyst (V2O5-WO3-TiO2). Its catalyst forming technology includes monolithic honeycomb, plate, and corrugated plate forming. It is mainly prepared using titanium dioxide as the paste material. Not only is the preparation process complex, but it is also intolerant of errors. Once the forming process deviates from the optimal conditions, the catalyst will fail to meet the usage requirements and will be discarded. In addition, the catalyst is also prone to damage during transportation, resulting in product loss. Furthermore, due to its high density, this type of vanadium-based catalyst is difficult to apply in equipment scenarios such as ships and automobiles where the weight of the catalyst is strictly controlled.

[0006] Furthermore, in large-scale non-thermal power plants, cement kilns, and industrial boilers, the desired denitrification temperature is mostly below 300℃. Existing low-temperature denitrification catalysts are easily affected by fly ash, SO2, and H2O during actual production and operation, leading to rapid deactivation and preventing long-term normal use. These used catalysts (which fail to meet denitrification requirements due to wear or deactivation) are generally discarded directly, wasting resources and easily causing environmental pollution. Although some research has been conducted on catalyst cleaning and regeneration, such as using ultrasonic cleaning followed by acid / alkali washing to restore activity, under current production processes, the cost of catalyst cleaning and regeneration is high (approximately 40% of the price of new catalysts, with a chemical lifespan of 80%), and catalysts that have been used multiple times cannot be recycled, making it not an economically or environmentally efficient recycling method. Furthermore, chemical cleaning processes generally inevitably cause pollution. In other words, catalyst disposal and recycling also lead to higher costs, more complex post-processing, and more serious environmental pollution.

[0007] While the impregnation method for supporting precious metal-based catalysts has facilitated the recovery and utilization of precious metal components to some extent, there are still other losses during the extraction and filtration processes, resulting in incomplete recovery of the active precious metal substances. Furthermore, the recovery process still generates a large amount of wastewater and some toxic gases, and the recovery rate is only low. The process method needs further improvement.

[0008] Existing vanadium-based catalysts (V₂O₅-WO₃TiO₂) suffer from problems such as complex preparation processes (requiring calcination for 20-30 days), low mechanical strength (easily damaged during transportation), difficult regeneration (requiring acid / alkali washing, resulting in high costs), and environmental pollution. Furthermore, low-temperature denitrification catalysts are susceptible to SO₂ and H₂O poisoning, leading to high disposal costs and environmental pollution after disposal.

[0009] Advanced preparation technology and regeneration technology after deactivation of industrial denitration catalysts remain major challenges that need to be addressed.

[0010] In actual production applications, the yield rate of catalyst preparation, damage during transportation, and deactivation of catalysts under actual operating conditions are all unavoidable problems. There has been a long-standing demand in the industry for catalysts to operate stably, with high performance and high reliability for longer periods at a lower price. However, current preparation and regeneration technologies cannot enable catalysts to maintain high catalytic activity at a low operating cost.

[0011] Furthermore, discarded catalysts cannot be easily disposed of in an environmentally friendly manner. Because they contain heavy metals and other harmful substances, they can easily enter the environment during loading, unloading, transportation, storage, and disposal, thus harming the environment and the health of organisms (including humans) through contact, inhalation, and the food chain, and may even be carcinogenic. Some discarded catalysts also contain toxic components such as arsenic trioxide, arsenic pentoxide, and chromium trioxide (for example, not a common toxic component in denitrification catalysts, but can be replaced by vanadium pentoxide, a common component in denitrification catalysts). Improper disposal will occupy land, pollute water and soil, release harmful gases, and increase airborne particulate matter. The high cost of materials, equipment, and processes required for safe and proper disposal to meet environmental and legal compliance requirements makes it essentially unsuitable for industrial use. Therefore, the aforementioned chemical waste catalysts cannot be treated as general solid waste and must be entrusted to professional units with hazardous waste management licenses for recycling, utilization, and disposal to control environmental risks and ensure health and safety.

[0012] Chinese invention patent application CN117019136A, filed on July 28, 2023, by inventors who are partially identical to this application, discloses an integral low-temperature manganese / cerium honeycomb denitrification catalyst, wherein the catalyst is composed of cerium dioxide (CeO2) and manganese oxide (MnO2). x The catalyst, with titanium dioxide (TiO2) as the paste material and structural additives as the main active ingredient, was prepared by extrusion. Its catalytic activity and resistance to SO2 poisoning were evaluated under simulated industrial flue gas testing conditions. Experimental data show that the catalyst exhibits excellent low-temperature denitrification activity and resistance to SO2 poisoning, enabling the removal of nitrogen oxides from low-temperature flue gas in practical industrial applications.

[0013] However, existing catalyst preparation processes primarily use inorganic materials such as TiO2 as the paste material, which is prone to sintering. After repeated calcination, these materials lose their viscosity and become unusable. This makes it difficult to avoid issues such as low yield rates, damage during transportation, and catalyst deactivation under actual operating conditions. Catalysts prepared from TiO2 materials after multiple sinterings suffer reduced mechanical strength and structural damage, rendering them unusable. Furthermore, catalysts prepared using TiO2 and similar paste materials have limited mechanical strength and are brittle, making them susceptible to breakage and fracture during transportation and use.

[0014] Furthermore, in the recycling and treatment of catalysts after they have been deactivated, such as catalyst regeneration and hazardous waste treatment, the recovery of active components from large amounts of TiO2 is extremely energy-intensive, resulting in a large amount of energy waste and causing environmental pollution problems.

[0015] In summary, existing catalyst regeneration and recycling technologies are difficult and costly, resulting in poor technical performance and economic benefits, thus limiting their application and dim prospects. The disposal of hazardous waste from existing catalysts easily leads to resource waste and environmental pollution. Existing active material extraction technologies for catalyst recycling, such as hydrometallurgy and pyrometallurgy, are cumbersome, energy-intensive, and time-consuming. During catalyst regeneration, the cleaning and reloading (filling) of active materials are not only cumbersome but also significantly reduce the mechanical strength and catalytic performance of the final regenerated catalyst product. Furthermore, the remolding of the catalyst paste after regeneration affects its mechanical strength, and hazardous waste requires special treatment.

[0016] Therefore, based on the above, the industry needs to continuously innovate and create technologies related to the preparation, materials, structure, molding, and regeneration of SCR catalysts, and improve existing catalyst composition, structure, configuration, and molding techniques. It is necessary to innovatively improve or realize a molded catalyst and its preparation process that can be repeatedly molded, facilitates post-processing and material recycling, and is regenerable and recyclable, in order to mitigate or even overcome the shortcomings of existing technologies and achieve more beneficial technical effects and technological advancements.

[0017] The information included in this background section of this application specification, including any references cited herein and any descriptions or discussions thereof, is included for technical reference purposes only and is not intended to limit the scope of this application. Utility Model Content

[0018] This application is made in view of the foregoing and other further ideas.

[0019] The inventors of this application have surprisingly discovered, through research and repeated experiments and tests, that polymer-supported catalysts (as a substrate / carrier / backbone) can be regenerated and reused. This application demonstrates through research and testing that polymer-based (or carrier / backbone) catalysts can be regenerated using a simplified reforming process suitable for industrial-scale production, enabling multiple uses, significantly reducing material and production costs, and greatly reducing or even virtually eliminating negative environmental impacts.

[0020] The inventors of this application have surprisingly discovered through research that this application can utilize a thermoplastic catalyst molding process, using thermoplastic materials to replace TiO2 and other materials as the catalyst's framework (carrier) material. Simultaneously, the powdered catalyst components can act as a binder for the thermoplastic material, helping to better bond and combine the various components / structures of the molded thermoplastic-based SCR catalyst. Ultimately, through the concept and technology of this application, the powdered catalyst can be thermoplastically molded and repeatedly molded into an industrial-grade catalyst with substantially stable catalyst activity, stable surface physicochemical properties, robust and lightweight, and regenerable through repeated molding. This catalyst can replace existing low-temperature denitrification catalysts and can be applied in a wide range of fields, including ships, automobiles, thermal power plants, incineration plants, cement plants, and gas scrubbing equipment, where lightweight catalysts are required.

[0021] According to one aspect of the basic concept of this application, a low-temperature SCR catalyst is provided that uses thermoplastic plastics instead of traditional support materials, such as TiO2, as the traditional skeleton (support) material. The preparation process is simplified through molding processes such as thermoplasticizing / hot pressing / extrusion, and the pore / channel structure of the catalyst can be selectively increased by pore-forming agents. This low-temperature SCR catalyst can be regenerated after deactivation by crushing and reshaping, achieving regeneration and recycling.

[0022] Some key aspects of the inventive concept of this application are further described below:

[0023] (1) Thermoplastic plastics can replace traditional carrier materials such as TiO2 as catalyst carrier skeleton materials, simplifying and facilitating the preparation and regeneration processes of catalysts.

[0024] Industrial denitrification catalysts (nitrogen oxides (NOx)) prepared by traditional processes xGenerally, TiO2 and other materials are used as the main paste material. The active components are either mixed into the mud during the molding process or impregnated and loaded after the preform material is prepared. The finished catalyst is then obtained through calcination and cutting. The calcination process causes the active substances to precipitate from the solution and also sintersulates the preform material, making it more tightly bonded. The production of a batch of catalyst involves several processes: mixing, mud refining, aging, extrusion, drying, calcination, and cutting, which takes approximately 20-30 days. This application proposes using thermoplastic as the carrier skeleton material to replace the existing process. It only requires thorough mixing of thermoplastic powder and catalyst powder, followed by a thermoplastic process in a mold. After thermoplasticization, due to the special surface properties of the plastic material, there is almost no mold sticking, and the required monolithic catalyst material can be obtained from the raw materials in a very short time. Preparation by hot pressing requires even less time. Furthermore, the method reported in this application is limited by the hot melt temperature of the plastic material, which is lower than the calcination temperature of TiO2 material, resulting in a shorter heating time, no drying process, and rapid, integrated molding.

[0025] (2) The low-temperature denitrification catalyst is loaded with polymer material (i.e. thermoplastic material) and integrally molded to improve the mechanical strength of the integral catalyst.

[0026] Traditional industrial catalyst preparation processes typically use materials like TiO2 as the main paste material, which possesses a certain level of mechanical strength. However, different denitrification catalysts employ different active components. Adding active components can enhance catalytic activity, but excessive incorporation can reduce the binding properties of the TiO2 paste, leading to breakage and damage during the drying process. Even if no breakage or cracking occurs during preparation, uneven heating and excessive active component concentration in certain areas can cause catalyst breakage or damage after calcination. More likely, catalysts prepared from TiO2 are susceptible to compression and impact during transportation, resulting in breakage and damage. Furthermore, catalysts with insufficient mechanical strength may collapse and break during use due to excessively high flue gas flow rates and pressure drops, rendering them unusable.

[0027] The preparation method using thermoplastic as a carrier skeleton material described in this application enables the use of thermoplastic material as the catalyst body, resulting in stable physicochemical properties, superior mechanical strength, and the ability to maintain the overall structure of the catalyst during normal transportation and use without damage, while withstanding greater flue gas pressure drops. Furthermore, the preparation process eliminates the need for prolonged drying and calcination, requiring only a single thermoplasticizing process, significantly simplifying the process flow, reducing the possibility of low yield rates due to process errors, and allowing for the reshaping of waste catalysts resulting from operational errors, thus conserving resources.

[0028] In addition, various thermoplastics, because their softening temperature is higher than the catalyst's operating temperature window, can provide stable support for the catalyst material to operate smoothly, and the two can be combined very well.

[0029] (3) The addition of pore-forming agents provides more pore structures for the catalyst.

[0030] During the thermoplastic molding process, uneven heating within the mold naturally generates bubbles and voids, which is undesirable in plastic part manufacturing. However, this is desirable in catalyst preparation, as bubbles and channel structures effectively increase the specific surface area, exposing more catalyst active sites and thus enhancing catalytic activity. Building upon this, we added a pore-forming agent during the thermoplastic process and incorporated a water washing / solution immersion step to remove these bubbles (e.g., through dissolution), resulting in a final product with an even greater number of pores.

[0031] (4) Simplify the catalyst regeneration process and turn the catalyst from waste to recycling.

[0032] The main causes of catalyst deactivation are fly ash clogging the catalyst channels and the influence of SO2 and H2O. For deactivated catalysts, we perform a simple cleaning process to remove fly ash and deposited ammonium sulfate from the catalyst surface. Then, we physically crush the shaped catalyst into powder and re-thermoplasticize it. During the crushing process, we collect all the powder samples. In the re-forming process, almost no catalyst powder needs to be added, and the sample size remains almost unchanged after re-forming, with no decrease in catalytic activity, essentially achieving catalyst recycling.

[0033] (5) The change in the substrate material gives the catalyst resistance to water poisoning.

[0034] Polymer materials, due to their stable physicochemical properties and non-wetting properties, can be used as catalyst supports to address water poisoning issues. In other catalytic reactions, polymer substrates can effectively promote the rapid removal of water, thereby improving reaction activity. The physical mixing of catalyst powder and hydrophobic polymer materials has also been shown to enhance the catalyst's resistance to water poisoning. This application utilizes thermoplastics as the catalyst support material. After thorough mixing of the catalyst powder and thermoplastics, such as through thermoforming, there may be an immersion process during preparation, but this does not affect the catalyst's catalytic activity because the hydrophobic polymer matrix material provides the catalyst with excellent resistance to water poisoning.

[0035] According to one aspect of the concept of this application, a reformable and regenerable low-temperature SCR catalyst is provided, the low-temperature SCR catalyst comprising: a thermoplastic support framework, wherein the shape of the thermoplastic support framework is selected from at least one of flat, corrugated, honeycomb, granular, cloth, tubular, rod, mesh, and porous sponge; and a low-temperature SCR catalyst active portion integrally formed with and supported by the support framework; wherein the low-temperature SCR catalyst is configured to be regenerable by reforming the thermoplastic support framework into one of the following shapes: flat, corrugated, honeycomb, granular, cloth, tubular, rod, mesh, and porous sponge.

[0036] According to one embodiment, the active portion of the low-temperature SCR catalyst includes a low-temperature denitrification catalytic active material.

[0037] According to one embodiment, the low-temperature denitrification catalytic active material comprises at least one of Mn / Ce catalytic material, V-based catalytic material, or Cu-based catalytic material.

[0038] According to one embodiment, the carrier skeleton has an internal porous structure.

[0039] According to one embodiment, the internal porous structure accounts for more than 10% of the volume percentage of the carrier skeleton.

[0040] According to one embodiment, the active portion of the low-temperature SCR catalyst is composited in the support framework in the form of dispersed particles.

[0041] According to one embodiment, the active portion of the low-temperature SCR catalyst is coated and composited onto the support framework in the form of a thin film.

[0042] According to one embodiment, the operating temperature of the low-temperature SCR catalyst is below 300°C.

[0043] According to one embodiment, the thermoplastic 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, fluororubber (FKM), silicone rubber (VMQ), and nylon (PA).

[0044] According to one embodiment, the support framework of the low-temperature SCR catalyst has a self-supporting configuration both before and after reshaping, thereby enabling the low-temperature SCR catalyst to have a self-supporting configuration that does not require external support within a set operating temperature range.

[0045] This application overcomes many inherent 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 traditional production processes and steps of traditional catalysts / modules; and the lightweight catalyst module resulting from the nature of the carrier material in this application, which replaces the bulkiness of traditional catalysts / modules and reduces the difficulty of disassembly, assembly and transportation of traditional catalysts / modules, etc.

[0046] Further embodiments of this application can achieve other advantageous technical effects not listed one by one. These other technical effects may be partially described below and can be expected and understood by those skilled in the art after reading this application. Attached Figure Description

[0047] 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. A brief description of the drawings is as follows.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] Figure 5 This illustration schematically demonstrates a performance comparison between a PEEK-based catalyst prepared by thermoplastic molding according to an embodiment of this application and an industrial catalyst.

[0055] Figure 6 The illustration schematically shows a performance comparison between PEEK, PFA, and PPS-based catalysts prepared by thermoplastic molding according to an embodiment of this application and industrial catalysts.

[0056] Figure 7 The illustration schematically demonstrates a performance comparison of different plastic-based catalysts prepared by hot pressing according to an embodiment of this application.

[0057] Figure 8 The SO2 poisoning performance test results of a PEEK-based catalyst according to an embodiment of this application and the SO2 poisoning performance test results of a PEEK-based catalyst after deactivation and re-forming are illustrated schematically.

[0058] Figure 9 The data illustrating the performance recovery of a PEEK-based catalyst according to an embodiment of this application after SO2 poisoning regeneration are shown schematically.

[0059] Figure 10 The illustration schematically shows the performance test results of a PEEK-based catalyst according to an embodiment of this application after multiple remolding and operation at a predetermined reasonable operating temperature.

[0060] Figure 11 The illustration shows an example of a thermoplastic molding process for preparing the low-temperature SCR catalyst of this application according to an embodiment of the present application.

[0061] Figure 12 This illustration schematically demonstrates an example of a hot-pressing process for preparing the low-temperature SCR catalyst of this application according to an embodiment of the present application.

[0062] Figure 13 This illustration schematically demonstrates an example of a hot extrusion molding process for preparing the low-temperature SCR granular catalyst of this application according to an embodiment of the present application, which requires preheating.

[0063] Figure 14 This illustration schematically demonstrates an example of a preheating-required hot extrusion molding process for preparing the low-temperature SCR honeycomb catalyst of this application according to an embodiment of the present application.

[0064] Figure 15 This illustration demonstrates an example of an extrusion molding process for preparing the low-temperature SCR granular catalyst of this application according to an embodiment of the present application, which does not require preheating or additional heating treatment.

[0065] Figure 16 This illustration demonstrates an example of a coating molding process for preparing the low-temperature SCR plate catalyst of this application according to an embodiment of the coating molding method.

[0066] Figure 17 An example of a regenerable fine SCR denitrification catalyst system according to an embodiment of this application is illustrated to demonstrate and describe the system and general configuration of the segmented catalyst (module / segment) arrangement of this application for fine SCR denitrification. Detailed Implementation

[0067] The details of one or more embodiments of this application will be set forth in the following description of the accompanying drawings and specific embodiments. Other features, objects, and advantages of this application will become clear from these descriptions, drawings, and claims.

[0068] It should be understood that the illustrated and described embodiments are not limited in application to the details of the construction and arrangement of the components set forth in the following description or illustrated in the drawings. The illustrated embodiments may be other embodiments and can be implemented or performed in various ways. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the various embodiments / examples of this application without departing from the scope or spirit of this disclosure. For example, features illustrated or described as part of one embodiment may be used with another embodiment to still produce another embodiment. Therefore, this disclosure covers such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0069] Similarly, it is understood that the phrases and terms used in this document are for descriptive purposes and should not be considered restrictive. The use of “including,” “contains,” or “has,” and their variations, in this document is intended to include, in an open-ended manner, the items listed thereafter, their equivalents, and any additional items.

[0070] The present application will now be described in more detail with reference to several specific embodiments thereof.

[0071] Generally speaking, the working principle of selective catalytic reduction (SCR) denitration catalysts mainly involves the following steps:

[0072] (i) External diffusion process: The process by which nitrogen oxides and ammonia diffuse from the bulk gas phase to the outer surface of the catalyst;

[0073] (ii) Internal diffusion process: reactants diffuse from the outer surface of the catalyst to the inner surface so that the reaction can occur at the active site;

[0074] (iii) Adsorption process: adsorption of reactants at active sites;

[0075] (iv) Catalytic reaction: At the active site of the catalyst and at a certain temperature, adsorbed nitrogen oxides (NOx) x ) and ammonia undergo a catalytic reduction reaction to produce nitrogen and water;

[0076] (v) Desorption process: The reaction products are released from the active site; and

[0077] (vi) Internal diffusion process: After the reaction products desorb from the active center, they diffuse from the inner surface of the catalyst to the outer surface.

[0078] Low-temperature SCR denitrification systems typically include a device for storing and injecting reducing agents (such as ammonia (NH3) or urea (CO(NH2)2)), an SCR control unit, and an SCR catalyst. Urea hydrolyzes and decomposes to produce ammonia. Under suitable low-temperature conditions (generally below 200–300°C), ammonia-selective catalytic reduction (NH3-SCR) can directly catalyze the reduction of nitrogen oxides (NOx) in flue gas. x It reacts with ammonia to produce harmless nitrogen and water, and can also absorb harmful flue gas particles. The corresponding reaction formula is as follows:

[0079] CO(NH2)2 + H2O = CO2↑ + 2NH2↑

[0080] 4NH3 + 4NO + O2 => 4N2 + 6H2O

[0081] 4NH3 + 2NO2 + O2 => 3N2 + 6H2O

[0082] In terms of traditional technologies, TiO2-based catalysts have gradually replaced Pt-Rh and Pt-series catalysts. These catalysts primarily consist of V2O5 as the active component, with WO3 and MoO3 serving as antioxidant and anti-poisoning auxiliary components. For example, they mainly consist of V2O5 (WO3), Fe2O3, CuO, and CrO. x MnO x Composed of metal oxides such as MgO, MoO3, and NiO, or mixtures thereof, it typically uses TiO2, Al2O3, ZrO2, SiO2, and activated carbon (AC) as supports to undergo reduction reactions with reducing agents such as liquid ammonia or urea in the SCR system, making it the mainstream catalyst product for SCR denitrification engineering in power plants.

[0083] The inventors of this application have discovered that, in the field of catalysts, polymer-supported nanocatalytic particles, as carrier materials, can be regenerated and reused. This allows used nanocatalytic particles to be regenerated and reused in new or regenerated catalysts. This regenerable characteristic makes it possible for pollutants generated during catalyst production to not flow back into the environment and cause pollution. Organic polymer supports (or substrates, frameworks, etc.) for catalysts typically have a relatively low exposure of active sites due to their small surface area. Therefore, additional additives are needed to help generate a large number of porous structures and increase their specific surface area. Furthermore, this method accelerates the diffusion of water out of the catalyst, contributing to its high activity and long-term stability.

[0084] One of the main concepts of this application is that hydrophobic organic polymers, especially hydrophobic thermoplastics, are preferably used as the support framework for low-temperature SCR catalysts. On the one hand, this can achieve the above-mentioned technical advantages and is technically applicable to the application of low-temperature SCR catalysts (here, "low temperature" refers to the normal operating temperature of SCR catalysts, which is generally below 300°C, more preferably below 250°C). On the other hand, the thermoplasticity of such plastics makes it possible to carry out large-scale regeneration processes for the low-temperature SCR catalysts.

[0085] Of course, those skilled in the art will understand that using thermoplastics (such as, but not limited to, PPS, PEEK, PBT, etc.) as a carrier / substrate material for low-temperature SCR catalysts can achieve more technical advantages and benefits, including but not limited to: easy cleaning, crushing and reshaping after sulfur (e.g., SO2) poisoning and deactivation (ammonium sulfate deposition); easy operation in a wide range of application environments, including low-ash areas, and easy cleaning and regeneration; the properties of thermoplastics make low-temperature SCR catalyst products lightweight, easy to transport and install, and less brittle, not easily damaged during transportation, installation and use; wide availability, low cost of material sources; non-toxicity and environmental friendliness of materials; extremely high yield (theoretical yield 100%, no defective products); extremely high recycling rate (theoretical recycling rate close to 100%).

[0086] The inventors of this application have discovered that the support / substrate material suitable for low-temperature SCR catalysts can be a thermoplastic material with a relatively high plasticizing temperature (e.g., its molding temperature is typically above approximately 200°C) as the support skeleton molding agent, such as, but not limited to, PBI; PI; TPI; PAI; PEEK; PPS; PTFE; PFA; ETFE; PCTFE, etc. The normal operating temperature of such thermoplastic-based "low-temperature" SCR catalysts is generally below 300°C, more preferably below 250°C.

[0087] The molding process for thermoplastic materials in preparing the low-temperature SCR catalyst of this application may include, but is not limited to: thermoplastic molding, hot pressing, extrusion molding, 3D printing molding, electrospinning molding, spraying molding, injection molding, compression molding, blow molding, calendering, rotational molding, vacuum forming (thermoforming), casting molding (injection molding), slush molding, casting, foaming molding, transfer molding (compression molding), filament winding, etc.

[0088] The low-temperature SCR catalyst of this application can be shaped into various forms (configurations including but not limited to: honeycomb catalyst products, plate catalyst products, corrugated plate catalyst products, tubular catalyst products, rod-shaped catalyst products, granular catalyst products, network catalyst products, porous solid foam catalyst products, etc.) after preparation. Based on the above concept and features of this application, these catalyst products can be reshaped and regenerated after use.

[0089] Thermoplastic molding, thermo-extrusion molding, and extrusion molding of low-temperature SCR catalysts

[0090] According to one aspect of the concept of this application, the thermoplastic molding of the low-temperature SCR catalyst of this application can effectively and rapidly thermoplasticize using polymeric thermoplastic plastic as the catalyst carrier material; the bonding effect is better and the molding effect is better after adding catalyst powder (which can act as a binder); the large number of pores generated during the thermoplasticizing process can make the molded 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 molding process. The low-temperature SCR catalyst of this application, which is thermoplasticized, can have a larger proportion of catalyst components, so its catalytic performance is better than that of existing catalysts under the same test conditions.

[0091] The thermoplastic polymer materials suitable for use in the low-temperature SCR catalyst of this application during thermoplastic molding and extrusion molding include: PEEK, PFA, PPS, PTFE, PBT, PEI, PES, PCTFE, ETFE, PAI, PBI, PI, FEP, PPA, PSU, PPSU, PE, PP, fluororubber (FKM), silicone rubber (VMQ), and nylon (PA). These materials are all polymer materials with rapid thermoplasticization capabilities and stable physicochemical properties.

[0092] In this embodiment, the catalyst powder used is selected from catalyst materials with good low-temperature denitrification performance, such as: Mn / Ce low-temperature denitrification catalyst, V-based catalyst, Cu-based catalyst, etc.

[0093] For a detailed introduction to the Mn / Ce low-temperature denitrification catalyst and related formulations, please refer to Chinese invention patent application CN117019136A filed by the inventors of this application on July 28, 2023, the relevant content of which is incorporated herein by reference.

[0094] Figure 1A and Figure 1B as well as Figure 2A and Figure 2B The illustration shows the catalyst product prepared by the thermoplastic molding method of this application. Among them, 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. 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 illustration shows that there are a large number of pore structures in the flue gas channels of this thermoplastic honeycomb catalyst product, which are formed by the addition of pore-forming agents.

[0095] Figure 11 The illustration shows an example of a thermoplastic molding process for preparing the low-temperature SCR catalyst of this application according to an embodiment of the present application.

[0096] The following uses PEEK material as an example, combined with the attached... Figure 11 As shown, the thermoplastic molding process of the low-temperature SCR catalyst of this application is further described.

[0097] 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 place in a cylindrical stainless steel mold.

[0098] 2) Seal the stainless steel mold with a stainless steel press, place it in a muffle furnace and heat it at 300-320℃ and about 10.0MPa pressure for 6 hours to plasticize and form it.

[0099] 3) After water cooling, soak for 1-24 hours to remove the pore-forming agent, and dry to obtain a cake-shaped thermoplastic catalyst. Perform pore-drilling on a CNC machine tool to obtain a honeycomb-shaped low-temperature SCR catalyst product, for example... Figure 1A and Figure 2A and Figure 2B As shown.

[0100] The following section uses PEEK material as an example to further introduce the thermal extrusion molding process of the low-temperature SCR catalyst in this application.

[0101] 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 evenly to form an extrudable mixture;

[0102] 2) Load the mixture into the hopper of the extruder, set the heating temperature of the extruder to 320℃, and form a molten mixture;

[0103] 3) The molten mixture is extruded through the die of an extruder to form slender catalyst rods of the required cross-sectional size and shape, and then water-cooled;

[0104] 4) After water cooling, soak in the cleaning solution for 1.5 hours to remove the pore-forming agent, dry, and then cut using a cutting device to obtain granular low-temperature SCR catalyst of the desired size and dimensions, such as... Figure 1B As shown. The cleaning solution is one or more of the following: ammonia water, water, sodium bicarbonate, ammonium carbonate, and trisodium phosphate solution. The pH value of the solution should be maintained between 5 and 8, and the preferred pH value of the sodium bicarbonate solution is 7.5.

[0105] Figure 13 This illustration schematically demonstrates an example of a hot extrusion molding process for preparing the low-temperature SCR granular catalyst of this application according to an embodiment of the present application, which requires preheating.

[0106] The following uses PFA material as an example, combined with the attached... Figure 13 As shown, the following is an example of the hot extrusion molding process steps for the low-temperature SCR catalyst of this application:

[0107] 1) Mix 200-mesh Mn / Ce catalyst powder (8 parts by weight) with PFA powder (20 parts by weight), add NaCl, CaSO4, (NH4)2CO3, carbon powder, etc. as pore-forming agents (10 parts by weight), and mix thoroughly to form a thermo-extruded molding mixture.

[0108] 2) Load the mixture into the hopper of the extruder, set the heating temperature of the extruder to 350℃, and form a molten mixture;

[0109] 3) The molten mixture is extruded through the die of an extruder to form slender catalyst rods of the required cross-sectional size and shape, and then water-cooled;

[0110] 4) After water cooling, soak in the cleaning solution for 1.5 hours to remove the pore-forming agent, dry, and then cut using a cutting device to obtain granular low-temperature SCR catalyst of the desired size and dimensions, such as... Figure 1B As shown. The cleaning solution is one or more of the following: ammonia water, water, sodium bicarbonate, ammonium carbonate, and trisodium phosphate solution. The pH value of the solution should be maintained between 5 and 8, and the preferred pH value of the sodium bicarbonate solution is 7.5.

[0111] Figure 14 This illustration schematically demonstrates an example of a preheating-required hot extrusion molding process for preparing the low-temperature SCR honeycomb catalyst of this application according to an embodiment of the present application.

[0112] The following uses PFA material as an example, combined with the attached... Figure 14 As shown, the following is an example of the hot extrusion molding process steps for the low-temperature SCR catalyst of this application:

[0113] 1) Mix 200-mesh Mn / Ce catalyst powder (8 parts by weight) with PFA powder (20 parts by weight), add NaCl, CaSO4, (NH4)2CO3, carbon powder, etc. as pore-forming agents (10 parts by weight), and mix thoroughly to form a thermo-extruded molding mixture.

[0114] 2) Load the mixture into the hopper of the extruder, set the heating temperature of the extruder to 350℃, and form a molten mixture;

[0115] 3) The molten mixture is extruded through the honeycomb mold of the extruder to form a honeycomb catalyst with the required number and size of channels, and then immediately water-cooled.

[0116] 4) After water cooling, soak in the cleaning solution for 1.5 hours to remove the pore-forming agent, dry, and then cut using a cutting device to obtain the required length of honeycomb-shaped low-temperature SCR catalyst, for example... Figure 1A As shown. The cleaning solution is one or more of the following: ammonia water, water, sodium bicarbonate, ammonium carbonate, and trisodium phosphate solution. The pH value of the solution should be maintained between 5 and 8, and the preferred pH value of the sodium bicarbonate solution is 7.5.

[0117] Figure 15 This illustration demonstrates an example of an extrusion molding process for preparing the low-temperature SCR granular catalyst of this application according to an embodiment of the present application, which does not require preheating or additional heating treatment.

[0118] The following uses PFA material as an example, combined with the attached... Figure 15 As shown, the extrusion molding process steps of the low-temperature SCR catalyst of this application are further described below:

[0119] 1) Mix 200-mesh Mn / Ce catalyst powder (8 parts by weight) with PFA powder (20 parts by weight), add NaCl, CaSO4, (NH4)2CO3, carbon powder, etc. as pore-forming agents (10 parts by weight), and mix thoroughly to form a (cold) extrusion molding mixture.

[0120] 2) Load the mixture into the hopper of the extruder and set the pressure of the extruder to 30MPa. This process does not require heating / preheating.

[0121] 3) Fill the mixed powder into the mold opening of the extrusion molding machine, and use the extrusion mold to extrude the powder. The extrusion molding time is about 20 seconds. Open the extrusion mold to demold, and the granular catalyst falls into the collection bag through the demolding port.

[0122] 4) Immerse in the cleaning solution for 1.5 hours to remove the pore-forming agent, and dry to obtain granular low-temperature SCR catalyst of the desired size and shape, such as... Figure 1B As shown. The cleaning solution is one or more of the following: ammonia water, water, sodium bicarbonate, ammonium carbonate, and trisodium phosphate solution. The pH value of the solution should be maintained between 5 and 8, and the preferred pH value of the sodium bicarbonate solution is 7.5.

[0123] Hot pressing of low-temperature SCR catalysts

[0124] 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. 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. Figure 3C schematically shown Figure 3A The photograph shown is of a single thermoplastic plate catalyst, demonstrating the presence of numerous porous structures on the surface of the plate catalyst.

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

[0126] Figure 12 This illustration schematically demonstrates an example of a hot-pressing process for preparing the low-temperature SCR catalyst of this application according to an embodiment of the present application.

[0127] The following uses FEP material as an example, combined with the attached... Figure 12 As shown, the hot pressing process of the low-temperature SCR catalyst of this application is further described.

[0128] 1) Mix FEP emulsion (3 parts by weight) with catalyst powder (e.g., Mn / Ce low-temperature denitration catalyst, 10 parts by weight) thoroughly to obtain a mixed powder. Coat the mixed powder onto both sides of a thermoplastic sheet (e.g., FEP) to obtain a blank. Separate the blanks with polyimide film, cover both ends with stainless steel plates, and place them on a hot press.

[0129] 2) The hot pressing process is carried out in two stages on a hot press. The specific parameters for the hot pressing process are as follows:

[0130] The first stage of hot pressing temperature is 120-200℃, and the first stage of hot pressing pressure is 50-80 kg / cm². 2 Hot pressing time: 180 seconds (s);

[0131] The second stage hot-pressing temperature is 200-300℃, and the second stage hot-pressing pressure is 50-80 kg / cm². 2 Hot pressing time: 180s.

[0132] 3) Cool the hot-pressed catalyst to room temperature, clean and dry it, open the partition, and obtain the formed plate-type catalyst product, such as... Figures 3A-3C As shown schematically.

[0133] Those skilled in the art will understand that, in the above process step 1), a certain proportion of pore-forming agents, such as NaCl, CaSO4, (NH4)2CO3, carbon powder, etc., can be selectively added to the above mixture according to the target application and performance requirements.

[0134] Coating and molding of low-temperature SCR catalysts

[0135] Figure 16 This illustration shows an example of the coating molding process steps for preparing the low-temperature SCR plate catalyst of this application according to an embodiment of the coating molding method.

[0136] Weigh out 1 part of thermoplastic emulsion (or powder), such as 20% FEP content (by mass) FEP emulsion, and optionally add 1 part by mass of NaCl crystals (as a pore-forming agent). Mix thoroughly until almost completely dissolved, then add the resulting mixture to 1 part by mass of catalyst powder and mix. Stir the resulting slurry thoroughly for 10-15 minutes to obtain an FEP slurry material for coating molding.

[0137] The FEP mud-like material is then coated onto an 80-mesh metal mesh to obtain a coated sheet metal plate. The coated sheet metal plate is then placed in a 100℃ oven for initial drying for 15 minutes to ensure that all NaCl crystals, which serve as pore-forming agents, are precipitated. Subsequently, the metal plate is placed in a 260℃ oven for drying for 20-30 minutes. The coating process is repeated multiple times, for example, more than 3 times.

[0138] As an alternative skeleton, thermoplastic materials, including but not limited to FEP plastic skeletons, can be used to replace 80-mesh metal mesh. For example, alternatively, FEP paste-like material can also be coated onto a mesh-like, plate-like, or porous plate-like FEP plastic skeleton through at least one coating process, and if a pore-forming agent is added, an alternative precipitation process can be performed.

[0139] Afterwards, the NaCl crystals occupying the porous structure are washed away through a cleaning process, and then the product is dried to obtain a plate-shaped (plate-like) low-temperature denitration catalyst.

[0140] The aforementioned coated plate-type low-temperature denitrification catalyst will become deactivated after a period of low-temperature denitrification catalytic operation. The deactivated coated plate-type catalyst undergoes catalyst layer stripping (e.g., through mechanical stripping, chemical stripping, ultrasonic stripping, etc.). The collected broken block and sheet catalyst pieces are then pulverized and selectively supplemented with appropriate amounts of active components. The catalyst is then regenerated into a molded low-temperature denitrification catalyst through methods such as recoating, thermoplasticizing, hot pressing, or extrusion molding.

[0141] In the plate-shaped (plate-like) low-temperature denitration catalysts prepared by the above coating and molding methods, the preferred carrier skeleton is a thermoplastic carrier skeleton. For example, the carrier skeleton may have the same or different thermoplastic material composition as the thermoplastic emulsion (or powder). For example, the carrier skeleton may be metallic or a non-metallic material. The thermoplastic carrier skeleton preferably has the same plastic composition as the thermoplastic emulsion (or powder), thereby facilitating and benefiting subsequent remolding and recycling processes.

[0142] The carrier skeleton can have a shape selected from sheet, plate, corrugated plate, cloth, tubular, granular, mesh structure, honeycomb or porous sponge.

[0143] The above coating molding process is applicable to the following thermoplastics as carrier skeletons: PEEK, PFA, PPS, PTFE, PBT, PEI, PES, PCTFE, ETFE, PAI, PBI, PI, FEP, PPA, PSU, PPSU, PE, PP, fluororubber (FKM), silicone rubber (VMQ), and nylon (PA).

[0144] In the case where the above-mentioned coated plate-type low-temperature denitrification catalyst has a thermoplastic support skeleton, the above-mentioned coating process may further include: after cleaning, crushing and reshaping the deactivated low-temperature SCR catalyst skeleton, coating it with a preferably identical thermoplastic emulsion containing SCR catalytic active component powder, and reprocessing it (e.g., through drying, curing and other processes) to regenerate it.

[0145] In cases where the above-mentioned coated plate-type low-temperature denitrification catalyst has a non-thermoplastic plastic material, such as metal or infinitely non-metallic carrier skeleton, the above-mentioned coating molding process may further include: peeling off the deactivated catalyst coating layer of the coated plate-type catalyst (e.g., by mechanical peeling, chemical peeling, ultrasonic peeling, etc.), collecting the broken block or sheet catalyst after peeling, adding thermoplastic plastic material and crushing it to form a mixed powder, selectively adding appropriate amounts of active components and / or foaming agents, pore-forming agents, etc., and remolding it through a remolding process other than coating molding, such as but not limited to thermoplastic, hot pressing, extrusion molding, etc., to become a remolded and regenerable low-temperature denitrification catalyst, the shape of which is not limited to plate.

[0146] The above-mentioned coating and molding process enables the carrier skeleton to have a self-supporting configuration both before and after re-molding and coating, thereby enabling the low-temperature SCR catalyst to have a self-supporting structure without external support within the set operating temperature range.

[0147] Regeneration of low-temperature SCR catalyst

[0148] An important inventive concept and key advantage of this application is that the low-temperature SCR catalyst of this application can be easily regenerated through a reshaping (re-shaping) process.

[0149] The following section uses the PEEK-based low-temperature SCR catalyst of this application as an example to further introduce the process method for regenerating the low-temperature SCR catalyst of this application.

[0150] 1) The deactivated (e.g., deactivated due to sulfur poisoning) PEEK-based thermoplastic catalyst is selectively cleaned, for example by ultrasonic cleaning to remove fly ash and ammonium sulfate deposits from the surface, dried, and then placed in a clean crusher for pulverization, for example, after crushing and passing through a 10-mesh sieve to obtain recycled powder for remolding.

[0151] 2) Add an appropriate proportion of a pore-forming agent (refer to the previous example) to the above recycled powder, mix thoroughly, and then place in a mold.

[0152] Pore-forming agents include, for example, NaCl, CaSO4, (NH4)2CO3, carbon powder, etc., and the addition ratio can be, for example, 10%-150% by weight of the recycled powder. An example of a pore-forming agent is NaCl, which is added at a ratio between 50%-120% by weight of the recycled powder.

[0153] 3) Add the mixed powder into a cylindrical mold, seal the mold with a press, and place it in a muffle furnace for thermoplastic molding. Heat and plasticize at 300-320℃ and 1MPa-5MPa pressure for 2-12 hours. If the recycled powder particles are larger, the molding time in the remolding process can be appropriately extended.

[0154] 4) After thermoforming, the mold is water-cooled / air-cooled to lower the temperature. Once cooled to room temperature, the catalyst is removed from the mold and water-cooled again until completely cooled to room temperature. It is then transferred to a cleaning solution to wash away the pore-forming agent. The soaking time in the cleaning solution is 1-12 hours. The cleaning solution can be one or more of ammonia, sodium bicarbonate, ammonium carbonate, or trisodium phosphate solution, and its pH value can be maintained between 5 and 8. Afterwards, the catalyst is perforated on a CNC machine tool to obtain a honeycomb-shaped low-temperature SCR catalyst.

[0155] In this regard, those skilled in the art will understand that in the above-described process step 1), a certain proportion of catalyst powder (e.g., 10% Mn / Ce powder) and / or PEEK powder can be selectively added to the regenerated powder to compensate for possible losses in composition and performance. Of course, this is not necessary. Test studies have shown that without adding catalyst and / or polymer powder, the low-temperature SCR catalyst of this application can still be successfully regenerated with minimal impact on its catalytic performance. Experimental data show that the denitrification efficiency of the low-temperature SCR catalyst of this application after regeneration is comparable to that of existing industrial catalysts, and its activity can be maintained at least 80%, as detailed below.

[0156] Those skilled in the art will understand that the aforementioned honeycomb-shaped low-temperature SCR catalyst can be reshaped into other shapes as needed during remolding and regeneration, such as rod-shaped, granular low-temperature SCR catalysts, etc., and does not necessarily have to be reshaped into a honeycomb-shaped low-temperature SCR catalyst.

[0157] A fine SCR denitrification catalyst system capable of multiple regeneration and its operation

[0158] Figure 17 An example of a regenerable fine SCR denitrification catalyst system according to an embodiment of this application is illustrated to demonstrate and describe the system and general configuration of the segmented catalyst (module / segment) arrangement of this application for fine SCR denitrification.

[0159] According to this embodiment, a low-temperature selective catalytic reduction (SCR) system for flue gas denitrification is introduced, which includes the low-temperature SCR catalyst of this application, such as a catalyst module prepared by thermoplastic molding and extrusion molding processes.

[0160] The fine SCR denitrification catalyst system of this application has better performance in terms of low-temperature SCR catalyst molding process, catalytic activity and mechanical strength, such as providing higher catalytic activity and better mechanical strength.

[0161] In this embodiment, the fine SCR denitrification catalyst system can be composed of several main parts:

[0162] (1) Replaceable catalyst module: a regenerable low-temperature SCR denitrification catalyst product that may contain multiple (e.g., multilayer) spaced apart from each other, such as plate-shaped, honeycomb-shaped and / or granular catalysts of the present application, for providing segmented / staged low-temperature SCR denitrification processes, such as below 300°C.

[0163] Preferably, as described above, the regenerable low-temperature SCR denitration catalyst may include: a support framework formed of thermoplastic plastic; and a low-temperature SCR denitration catalytic active component composited in and supported by the support framework. This refined SCR denitration catalyst system is configured to facilitate the removal and replacement of deactivated catalyst modules with new and / or regenerated catalyst modules. The regenerated catalyst module is obtained by removing the regenerable low-temperature SCR denitration catalyst from the deactivated catalyst module, regenerating it, and then reloading it. This regenerable low-temperature SCR denitration catalyst can be regenerated by remolding the thermoplastic support framework.

[0164] For example, multiple catalyst module segments include at least two of plate catalyst module segments, honeycomb catalyst module segments, and granular catalyst module segments.

[0165] According to a preferred example, the segmented catalyst module is arranged sequentially along the flue gas flow direction, consisting of a plate catalyst module segment, a honeycomb catalyst module segment, and a granular catalyst module segment. Following 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, the flue gas velocity naturally decreases sequentially, thereby removing, gradually and effectively, nitrogen oxides (NOx) from the flue gas according to these three catalyst module segments. x ), reduce NO x To reduce the content and achieve segmented, precise denitrification.

[0166] (2) Reactor: used to house the catalyst module and provide a suitable environment for SCR denitrification reaction.

[0167] The reactor is typically made of stainless steel (such as 316L or 304) or carbon steel (coated with a high-temperature resistant and corrosion-resistant coating). Its structure is cylindrical or cuboid, with specific dimensions designed according to the flue gas treatment capacity (e.g., diameter 2-5 meters, length 5-15 meters). Multiple catalyst modules can be installed inside the reactor (e.g., designed according to the flue gas flow direction, with plate catalyst modules, honeycomb catalyst modules, and granular materials arranged sequentially). The catalyst layer thickness can be 300-500 mm or thicker, with a layer spacing of 50-100 mm to optimize airflow distribution and reaction efficiency. A homogenizer (such as a baffle plate or static mixer) can be installed at the reactor inlet to ensure uniform mixing of flue gas and ammonia; a pressure balancing device can be installed at the outlet to prevent airflow disturbance.

[0168] The reactor can be equipped with a flue gas temperature control system (such as a heat exchanger or heater) to maintain the reaction temperature in, for example, a range of 200-300°C, to meet the requirements of low-temperature SCR catalysts.

[0169] The reactor can be equipped with built-in temperature sensors (such as thermocouples or infrared thermometers) and pressure sensors to monitor its operating status in real time and automatically adjust it through the control system.

[0170] For example, commercially available reactors include: the SCR-EE-LA / UR type reactor produced by Hebei Chengyu Environmental Engineering Co., Ltd., which supports low-temperature denitrification, adopts a modular design, and is suitable for boiler flue gas treatment; the dual-path vertically arranged reactor produced by Shandong Shoufeng Intelligent Environmental Protection Equipment Co., Ltd., which is suitable for various dust and flue gas conditions; and the honeycomb catalyst integrated reactor provided by Yuanchen Environmental Protection Technology Co., Ltd., etc.

[0171] (3) Injection system: used to inject reducing agent (such as ammonia or urea solution) into the reactor.

[0172] A typical injection system may include:

[0173] The ammonia / ammonia water injection system uses stainless steel (e.g., 316L) or ceramic nozzles. The structure can be a multi-hole atomizing type or a fan-shaped injection type, with an orifice diameter of 0.5-2mm and an adjustable injection angle of 30-90° to ensure thorough mixing of ammonia and flue gas. The nozzles can be evenly distributed along the flue cross-section, with a spacing of, for example, 200-500mm. The injection direction is arranged counter-currently or concurrently with the flue gas flow direction to enhance the mixing effect. The injection pressure and flow rate of ammonia / ammonia water are: working pressure 0.3-0.8MPa, flow rate range 50-500L / min (adjustable according to flue gas NO₂). x (Dynamic concentration adjustment); and

[0174] Ammonia supply and storage system, which may include storage tanks and conveying devices. Storage tanks may, for example, have a volume of 10-50 m³. 3The stainless steel storage tank is equipped with a level gauge, safety valve, and leak detection device, with a design pressure of 1.5 MPa. The conveying device can be a corrosion-resistant centrifugal pump (such as the Grundfos CR series) or a screw pump, with a flow accuracy of ±2% and support for PLC remote control.

[0175] Commercially available examples of injection systems include: the SNCR-EE-LA / UR model provided by Hebei Chengyu Environmental Engineering Co., Ltd., equipped with high-pressure atomizing nozzles and redundant safety systems; the "dual-path ammonia injection system" (suitable for high-dust flue gas) from Shandong Shoufeng Intelligent Environmental Protection Equipment Co., Ltd., etc., which can integrate a steam carrier gas device to enhance penetration.

[0176] (4) Optional control system: for monitoring and / or adjusting SCR reaction conditions, such as temperature, pressure and reducing agent injection amount, etc.

[0177] This control system can be used as a component of a fine SCR denitrification catalyst system, or it can be integrated into the application scenarios or equipment of a fine SCR denitrification catalyst system, such as the control systems of factories, workshops, waste gas treatment plants, ships, automobiles, etc.

[0178] As an example, the control system could be a PLC-based (such as Siemens S7-1200) automation system that integrates ammonia flow meters (such as mass flow meters) and NO... x A concentration sensor (such as an ultraviolet analyzer) and a temperature feedback module are used to achieve the ammonia-nitrogen molar ratio (NH3 / NO3). x Closed-loop control (target value 0.8-1.2). Furthermore, in emergency situations, an ammonia shut-off valve (such as an ASCO solenoid valve) can be triggered with a response time of <1 second.

[0179] In this embodiment, the general operation of the fine SCR denitrification catalyst system is as follows:

[0180] (1) System startup: After the system is started, the control system can automatically or manually adjust the reaction condition parameters in the reactor according to the flue gas conditions, such as reaction temperature, pressure, reducing agent injection amount, etc.

[0181] (2) SCR catalytic denitrification reaction: The injection system injects a reducing agent into the reactor, which reacts with NO in the flue gas. x The low-temperature SCR catalyst of this application reacts on its surface to generate nitrogen and water.

[0182] (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.

[0183] (4) Regeneration of the fine SCR denitrification catalyst system: After a period of time or a predetermined service life, the low-temperature SCR denitrification catalyst product is removed from the catalyst module, and the low-temperature SCR denitrification catalyst is reshaped and regenerated according to the regeneration method of this application (e.g., the regeneration of the low-temperature SCR catalyst described above). The regenerated low-temperature SCR catalyst is then reinstalled back into the catalyst module, thereby completing the regeneration of the fine SCR denitrification catalyst system. Thus, the regenerated fine SCR denitrification catalyst system can be reused and used normally.

[0184] More specifically, according to one example, the recycling method of a regenerable fine SCR denitrification catalyst system may include the following steps: removing the deactivated catalyst module from the reactor; pre-treating the low-temperature SCR denitrification catalyst of the deactivated catalyst module before regeneration; reshaping the pre-treated low-temperature SCR denitrification catalyst, which can achieve regeneration of the low-temperature SCR denitrification catalyst at the same time as reshaping; loading the regenerated low-temperature SCR denitrification catalyst back into the catalyst module, and then reloading the catalyst module back into the reactor, thereby realizing the recycling of the fine SCR denitrification catalyst system.

[0185] Pretreatment may include the following steps: crushing the deactivated catalyst module's low-temperature SCR denitration catalyst to obtain regenerated powder within the desired size range. The deactivated catalyst module's low-temperature SCR denitration catalyst may be cleaned before or after crushing. Screening may also be performed after crushing.

[0186] The regenerable fine SCR denitrification catalyst system of this embodiment uses the remolded and regenerable low-temperature SCR denitrification catalyst of this application. It has lower cost, a very simple and efficient remolding and regeneration process, almost 100% recyclability, almost no loss of regenerable catalytic activity, and better mechanical strength than existing catalyst products. It can be effectively reused to reduce NO in flue gas. x Emissions reduction, energy consumption reduction, pollution reduction, waste reduction, remolding and recycling, low maintenance costs, lightweight catalyst (module) and easy installation and transportation, etc., while meeting strict environmental protection and regulatory requirements.

[0187] Testing and evaluation of low-temperature SCR catalysts

[0188] Figure 4 A schematic diagram of an activity evaluation device for testing and evaluating the catalytic activity of the honeycomb low-temperature SCR catalyst of this application is shown. This activity evaluation device can be used to evaluate, for example, the catalytic activity of MnO4. xThe catalytic activity of the honeycomb low-temperature SCR catalyst of this application, with CeO2 as the catalyst component, was tested and evaluated. The reaction gas flow rate was controlled by a mass flow meter, and the mixture was introduced into a simulated flue gas channel in a mixing tank. After catalytic reaction treatment by the low-temperature SCR catalyst of this application, NO2 in the flue gas could be removed at the tail gas end. x Content testing.

[0189] Figure 5 This illustration schematically demonstrates a performance comparison between a PEEK catalyst prepared according to an embodiment of this application via thermoplastic molding (i.e., the PEEK-based low-temperature SCR catalyst of this application) and an industrial catalyst. In this test, the carrier gas was N2, the gas flow rate was 2.1 m / s, NO: 500 ppm, NH3: 500 ppm, O2: 5%, and the volume hourly space velocity (GHSV) was 6000 h⁻¹. -1 The tests included catalytic activity performance evaluations of the PEEK catalyst, the industrial-scale pilot-scale catalyst, and the industrial-use catalyst under the same size and testing conditions. The results show that the low-temperature SCR catalyst prepared using PEEK plastic as the support material exhibits high catalytic activity, comparable to that of industrial catalysts.

[0190] Figure 6 This illustration schematically demonstrates a performance comparison between PEEK, PFA, and PPS-based catalysts prepared by thermoplastic molding according to an embodiment of this application and industrial catalysts. In this test, the carrier gas was N2, the gas flow rate was 2.1 m / s, NO: 500 ppm, NH3: 500 ppm, O2: 5%, and the volume hourly space velocity (GHSV) was 6000 h⁻¹. -1 The test results are the performance test results of catalysts prepared by thermoplastic molding of different materials and industrial catalysts under the same size and test conditions. The content in parentheses after the material indicates the mass ratio of the catalyst active component in the support material. It can be seen that in the temperature range of 150℃~200℃, the catalytic performance of the molded catalysts prepared with PEEK and PFA materials as the base materials is almost the same as that of the industrial catalysts.

[0191] Figure 7 This illustration schematically demonstrates a performance comparison of different plastic-based catalysts prepared by a hot-pressing method according to an embodiment of this application. In this test, the carrier gas was N2, the gas flow rate was 2.1 m / s, NO: 500 ppm, NH3: 500 ppm, O2: 5%, and the volume hourly space velocity (GHSV) was 1500 h⁻¹. -1 The performance of the plate-type catalyst products of this application, prepared based on three different catalyst framework materials, is close to that of industrial-application catalysts.

[0192] Figure 8The diagram schematically illustrates the SO2 poisoning performance test results of a PEEK-based catalyst according to an embodiment of this application, as well as the SO2 poisoning performance test results of a PEEK-based catalyst reshaped after deactivation. In this test, the carrier gas was N2, the gas flow rate was 2.1 m / s, NO: 500 ppm, NH3: 500 ppm, O2: 5%, SO2: 200 ppm, and the volume hourly space velocity (GHSV) was 9000 h⁻¹. -1 In this comparative experiment, the operating status of the molded catalyst prepared using PEEK material as an example was tested at a relatively high SO2 concentration of 200 ppm. Within 24 hours, the catalyst's catalytic activity decreased slightly but stabilized at around 80% and eventually remained unchanged. After 24 hours, the catalyst was removed and remolded. The remolded catalyst was then subjected to the same anti-poisoning experiment. The results showed that in a new round of 24-hour SO2 poisoning tests, the catalyst performance remained stable above 80% without any decrease. This indicates that the remolding process does not affect the catalyst activity.

[0193] Figure 9 The data illustrating the performance recovery of a PEEK-based catalyst according to an embodiment of this application after SO2 poisoning regeneration are presented, demonstrating the data and performance of performance recovery and regeneration after SO2 poisoning.

[0194] Figure 10 The illustration schematically demonstrates the performance test results of a PEEK-based catalyst operating at a predetermined reasonable operating temperature after multiple remolding processes according to an embodiment of this application. During the remolding process, a small amount of powder loss due to breakage is sometimes unavoidable. Therefore, catalyst powder or thermoplastic powder can be appropriately added during the remolding process to ensure that the remolded catalyst maintains substantially the same size as before breakage. Generally, the amount added is preferably less than about 30% of the total catalyst amount before breakage. Excessive addition of catalytically active components will lead to a lower specific gravity of the thermoplastic material, weaker bonding between active components, and difficulty in molding.

[0195] Introduction to some technical effects of low-temperature SCR catalysts

[0196] In this invention, thermoplastic materials can be used as catalyst carriers (or matrix, framework, support framework, etc.) to replace existing conventional materials such as TiO2, thereby simplifying the integrated molding process of the catalyst and the catalyst regeneration process (e.g., through remolding). Using polymer thermoplastics as the carrier material and catalyst powder as the inorganic binder of the thermoplastics allows for a tight bond between the two during thermoplastic molding, improving the overall mechanical strength of the catalyst and preventing the leaching of the active components. The addition of a pore-forming agent enables the monolithic catalyst to have more fine pore structures during preparation, increasing the catalyst's specific surface area. Using thermoplastics as the base material allows for catalyst reuse, and the regeneration process is simple and quick, avoiding the energy waste and environmental pollution associated with traditional regeneration processes, and significantly extending the catalyst's lifespan.

[0197] Experiments have proven that the catalyst prepared by the preferred formulation of this invention exhibits denitrification activity similar to that of traditional industrial catalysts under the same size and testing conditions at 200℃, 150℃, and 100℃. Under the preferred catalyst formulation of this invention, the catalyst maintains over 80% of its performance without decline during long-term continuous operation at 200ppm SO2. After cleaning and reshaping the poisoned catalyst using the regeneration method described in this invention, the catalyst activity remains essentially consistent with its performance before reshaping at 200℃, 150℃, and 100℃. After multiple reshaping processes using the regeneration method described in this invention, the catalyst activity remains essentially consistent with its performance before the first reshaping at 200℃, 150℃, and 100℃.

[0198] The foregoing description of several embodiments of this application has been provided for illustrative purposes. This foregoing description is not intended to be exhaustive, nor to limit the application to the precise steps and / or forms disclosed; obviously, many modifications and variations can be made in light of the teachings above. The scope of this application and all its equivalents are intended to be defined by the appended claims.

Claims

1. A low-temperature SCR catalyst capable of being reformulated and regenerated, characterized in that, The low-temperature SCR catalyst comprises: A carrier skeleton for a thermoplastic plastic, wherein the shape of the carrier skeleton is selected from at least one of flat, corrugated, honeycomb, granular, cloth-like, tubular, rod-like, mesh-like, and porous sponge-like structures; and The low-temperature SCR catalyst active portion is integrally formed with and supported by the carrier framework. The low-temperature SCR catalyst can be regenerated by reshaping the thermoplastic carrier skeleton into one of the following shapes: flat plate, corrugated plate, honeycomb, granular, cloth, tubular, rod, mesh, and porous sponge.

2. The low-temperature SCR catalyst according to claim 1, characterized in that, The active component of the low-temperature SCR catalyst includes low-temperature denitrification catalytic active material.

3. The low-temperature SCR catalyst according to claim 2, characterized in that, The low-temperature denitrification catalytic active material includes at least one of Mn / Ce catalytic materials, V-based catalytic materials, or Cu-based catalytic materials.

4. The low-temperature SCR catalyst according to claim 1, characterized in that, The carrier skeleton has an internal porous structure.

5. The low-temperature SCR catalyst according to claim 4, characterized in that, The internal porous structure accounts for more than 10% of the volume percentage of the carrier skeleton.

6. The low-temperature SCR catalyst according to any one of claims 1-5, characterized in that, The active portion of the low-temperature SCR catalyst is composited in the support framework in the form of dispersed particles.

7. The low-temperature SCR catalyst according to any one of claims 1-5, characterized in that, The active portion of the low-temperature SCR catalyst is coated and composited onto the support framework in the form of a thin film.

8. The low-temperature SCR catalyst according to any one of claims 1-5, characterized in that, The operating temperature of the low-temperature SCR catalyst is below 300℃.

9. The low-temperature SCR catalyst according to any one of claims 1-5, characterized in that, The thermoplastic 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, fluororubber (FKM), silicone rubber (VMQ), and nylon (PA).

10. The low-temperature SCR catalyst according to any one of claims 1-5, characterized in that, The support framework of the low-temperature SCR catalyst has a self-supporting configuration both before and after reshaping, thereby enabling the low-temperature SCR catalyst to have a self-supporting structure that does not require external support within the set operating temperature range.

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