Ceramic fiber tube and method of making the same

Abstract

The application provides a ceramic fiber pipe and a preparation method thereof, and the ceramic fiber pipe has a pipe body, the pipe body has multiple fiber filter paper layers formed by laminating fiber cotton layers, and the pipe body comprises a denitration zone and a CO removal zone arranged along a wall thickness direction; the denitration zone comprises a layer of fiber filter paper layers, the CO removal zone comprises b layers of fiber filter paper layers, and a+b is greater than or equal to 100; nanoscale pores are formed between adjacent layers of fiber filter paper layers of the pipe body, and the pore diameter of the nanoscale pores is between 10nm and 50nm; and the CO removal zone further comprises a CO catalyst loaded in the pores and on the surface of the fiber cotton in a nanoscale. Through the different active components loaded in the functional zones of the carrier structure and the number of fiber filter paper layers and the nanoscale pore configuration of the fiber filter paper layers, the application realizes a trinity design of 'zoned loading-gradient pores-collaborative catalysis', breaks through the technical bottleneck of collaborative purification of complex flue gas and multiple pollutants, and has high efficiency, economy and long service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial waste gas treatment, and particularly relates to a ceramic fiber pipe and a preparation method thereof. BACKGROUND

[0002] Ceramic fiber filter pipes are usually used to filter solid particles, and are mainly used for dust removal in high-temperature environments in some industrial waste gas treatment, such as glass melting furnaces, coking, waste incineration, steel and coal industries. However, it is not common to directly use them to treat CO (carbon monoxide) waste gas. CO is a colorless and odorless toxic gas, and its binding capacity with hemoglobin is 200-300 times that of oxygen, which can cause human tissue hypoxia and cause headache, coma and even death. If CO leaks or is discharged beyond the standard in an industrial environment, it will directly threaten the life safety of workers and surrounding residents. The explosion limit of CO in the air is 12.5% to 74%, and if the concentration of CO in industrial waste gas is out of control, an explosion accident may occur (such as the coal gas purification system of a coking plant). Although CO is not a direct and powerful greenhouse gas, it can generate ozone (O3) through atmospheric photochemical reactions, indirectly exacerbating the greenhouse effect. CO reacts with nitrogen oxides (NOx) and volatile organic compounds (VOCs) to generate photochemical smog, causing haze and acid rain problems (such as the impact of untreated waste gas from a waste incineration plant on regional air quality).

[0003] The traditional CO treatment methods mainly include catalytic combustion method, thermal oxidation method, adsorption method and membrane separation method. The catalytic combustion method reduces the combustion temperature of carbon monoxide through a catalyst, so that it reacts with oxygen to generate carbon dioxide at a lower temperature. This method can effectively remove CO in waste gas, and the energy consumption is relatively low. However, the service life of the catalyst in this method is limited, and it needs to be replaced or maintained regularly; the temperature and composition of the waste gas need to be controlled, especially in high humidity or toxic gas conditions, the catalyst is easy to be poisoned or fail; the treatment effect of high-concentration CO is poor. The thermal oxidation method heats the waste gas to a high temperature, so that CO reacts with oxygen to generate CO2. This method consumes a lot of energy and requires a high-temperature environment, resulting in high operating costs; the treatment capacity is affected by the temperature and composition of the waste gas, and some CO may not be completely converted. The adsorption method uses solid adsorbents (such as activated carbon, molecular sieves, etc.) to adsorb CO, reducing the CO concentration in the waste gas; the adsorption capacity of the adsorbent in this method is limited, and it needs to be replaced or regenerated regularly. The membrane separation method separates CO from other gases through a selective permeation membrane; the membrane separation equipment in this method is relatively expensive, requiring a high initial investment; the selectivity of the membrane is affected by changes in the composition of the gas, and long-term use may cause membrane clogging or aging; the treatment effect of high-concentration CO waste gas is poor; the treatment capacity for complex industrial waste gas is low, and it is not suitable for treating large-scale waste gas.

[0004] If ceramic fiber filter tube is used for catalytic combustion (such as RCO), sulfur (S), chlorine (Cl), phosphorus (P) and other elements in the exhaust gas will react with the active sites of the catalyst, resulting in catalyst poisoning and failure. SUMMARY

[0005] In view of this, the embodiments of the present application provide a ceramic fiber tube and a preparation method thereof to eliminate or improve one or more defects in the prior art.

[0006] In a first aspect, the present application provides a ceramic fiber tube, the ceramic fiber tube has a tube body, the tube body has a plurality of layers of fiber filter paper formed by layering fiber cotton layers, the tube body includes a denitration zone and a CO removal zone arranged along the wall thickness direction; the denitration zone includes a layer of fiber filter paper layers stacked, and the CO removal zone includes b layers of fiber filter paper layers stacked, wherein a+b≥100; the tube body has nano-scale pores formed between adjacent layers of fiber filter paper layers, the pore size of the nano-scale pores is between 10-50 nm; the denitration zone further includes at least a denitration catalyst loaded in the pores and on the surface of the fiber filter paper layer, and the CO removal zone further includes at least a CO catalyst nano-scale loaded in the pores and on the surface of the fiber cotton.

[0007] In some embodiments, the denitration zone is located at the outer layer of the tube body, and the CO removal zone is located at the inner layer of the tube body; or, the CO removal zone is located at the outer layer of the tube body, and the denitration zone is located at the inner layer of the tube body.

[0008] In some embodiments, the denitration zone and the CO removal zone are configured to be at least partially overlapped, and the denitration catalyst and the CO catalyst are loaded in the fiber filter paper layers in the overlapping area.

[0009] In some embodiments, the total wall thickness of the tube body is 18-21 mm, the thickness of the denitration zone is configured to be not less than 2 / 3 of the total wall thickness, and the thickness of the CO removal zone is configured to be not less than 1 / 3 of the total wall thickness; or, the number of fiber filter paper layers of the denitration zone is configured to be not less than 2 / 3 of the total number of fiber filter paper layers of the tube body, and the number of fiber filter paper layers of the CO removal zone is configured to be not less than 1 / 3 of the total number of fiber filter paper layers of the tube body.

[0010] In some embodiments, the nano-scale pores of the tube body are asymmetric gradient pores, the pore size of the nano-scale pores changes in a gradient manner in the wall thickness direction and gradually increases in the direction from the outside to the inside, so that the resistance gradually decreases when the flue gas flows from the outside to the inside; the porosity of the tube body is ≥80%, and the porosity changes in a gradient manner in the wall thickness direction and gradually increases in the direction from the outside to the inside.

[0011] In some embodiments, the pipe body is a multi-layered fiber filter paper layer structure with nanoscale pores formed by centrifugal distribution of slurry configured by Al2O3 / SiO2 ceramic fibers and auxiliary materials, and the diameter of the Al2O3 / SiO2 ceramic fibers is 3-5 μm.

[0012] In some embodiments, the CO catalyst includes at least one of a Pd-based catalyst, a Pt-based catalyst, a copper-based catalyst, a cobalt-molybdenum-based catalyst, an iron-based catalyst, and a nitrogen-doped graphene catalyst.

[0013] In some embodiments, the denitration catalyst includes at least V2O5, TiO2, and CeO2.

[0014] In some embodiments, the CO catalyst includes Pt, the denitration catalyst includes V2O5, TiO2, and CeO2, and the mass proportions of the Pt, V2O5, TiO2, and CeO2 are 0.1-0.5 wt%, 22.4-23.7 wt%, 67.1-71.2 wt%, and 5-10 wt%, respectively; or, the CO catalyst includes Pt, the denitration catalyst includes V2O5, TiO2, and CeO2, and the pipe body further loads WO3 and MnO2; the mass proportions of the Pt, V2O5, TiO2, CeO2, WO3, and MnO2 are 0.1-0.5 wt%, 22.4-23.7 wt%, 67.1-71.2 wt%, 5-10 wt%, 1.5-2.5 wt%, and 1.5-2.5 wt%, respectively.

[0015] In a second aspect, the present application further provides a preparation method of the above ceramic fiber pipe, the thickness of the denitration zone is configured to be equal to the total wall thickness of the pipe body, and the CO removal zone is located in the inner layer of the pipe body and has a thickness configured to be equal to 1 / 3 of the total wall thickness of the pipe body, and the method comprises the following steps:

[0016] After the pipe body of the ceramic fiber pipe is prepared, a nano-impregnation liquid containing the denitration catalyst is used to realize gradient concentration loading of the denitration catalyst in the entire pipe wall thickness direction of the pipe body by using a directional impregnation process from the inside to the outside; during the impregnation of the denitration catalyst, the drying temperature of the outer layer of the pipe body is controlled to be higher than that of the inner layer, so that the evaporation amount of the nano-impregnation liquid of the outer layer is large to form migration and loading of the denitration catalyst, and the concentration of the denitration catalyst gradually decreases in the direction from the outside to the inside;

[0017] After the loading of the denitration catalyst is completed, a nano-impregnation liquid containing the CO catalyst is used to realize gradient concentration loading of the CO catalyst in the inner 1 / 3 pipe wall by using a directional impregnation process from the inside to the outside.

[0018] In a third aspect, the application further provides a method for preparing the ceramic fiber pipe, wherein the denitration zone is located in the outer layer of the pipe body and has a thickness equal to 2 / 3 of the total wall thickness of the pipe body; the CO removal zone is located in the inner layer of the pipe body and has a thickness equal to 1 / 3 of the total wall thickness of the pipe body, and the method comprises the following steps:

[0019] After the pipe body is prepared, a nano-impregnation liquid containing a denitration catalyst is used to realize gradient concentration loading of the denitration catalyst in the outer layer of the pipe body with a thickness of 2 / 3 of the total wall thickness by adopting an outside-in directional impregnation process.

[0020] A nano-impregnation liquid containing a CO catalyst is used to realize gradient concentration loading of the CO catalyst in the inner layer of the pipe body with a thickness of 1 / 3 of the total wall thickness by adopting an inside-out directional impregnation process.

[0021] In some embodiments, the outside-in directional impregnation process or the inside-out directional impregnation process adopts negative pressure on the outside of the pipe body or positive pressure on the inside of the pipe body to assist in permeation, so that the pressure difference between the inside and the outside is 0.05-0.1 MPa.

[0022] The specific surface area of the nano-impregnation liquid is greater than 60 m 2 / g, the laser particle detection data Dv(50) is between 0.075-0.1 μm, and Dv(99) is less than 1.0 μm.

[0023] After the denitration catalyst and the CO catalyst are fully loaded, the pipe body is subjected to gradient drying treatment at 60-100 ℃.

[0024] In a fourth aspect, the application further provides an application of the ceramic fiber pipe in the synergistic purification of CO, HC, VOCs and NOx in industrial waste gas, and the operation temperature is 180-320 ℃.

[0025] The ceramic fiber pipe of the application realizes strong oxidative degradation of CO, HC and VOCs and efficient reduction of NOx in a high-temperature environment by distinguishing the functional zones, configuring different catalysts and active components in different functional zones, and accurately adjusting the number of fiber filter paper layers and the pore configuration, and the excellent conversion rate and removal rate make it an ideal choice for waste gas treatment in the steel and coking industries, which can effectively deal with complex pollutant combinations and realize efficient and continuous waste gas purification.

[0026] Additional advantages, objects, and features of the application will be set forth in part by the description that follows, and will become apparent to those skilled in the art from the following description, or can be learned by practice of the application. The objects and other advantages of the application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0027] Those skilled in the art will appreciate that the objects and advantages of the application can be obtained by specific embodiments that are described herein and combinations of such embodiments. The application can achieve the above and other objects, and attains significant economic and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present application and, together with the description, further serve to explain the principles of the application. The components in the drawings are not to scale, emphasis instead being placed upon illustrating the principles of the application. For purposes of clarity and understanding, it is expressly intended that some portions of the drawings be shown exaggerated in scale, or out of proportion, to illustrate aspects of the application.

[0029] Figure 1 The schematic diagram of the whole structure of the ceramic fiber tube in an embodiment of the present application.

[0030] Figure 2 The schematic diagram of the layered structure of the tube body of the ceramic fiber tube in embodiment 1 of the present application.

[0031] Figure 3 The schematic diagram of the layered structure of the tube body of the ceramic fiber tube in embodiment 2 of the present application.

[0032] Figure 4 The schematic diagram of the layered structure of the tube body of the ceramic fiber tube in embodiment 3 of the present application.

[0033] Figure 5 The photograph of the actual section of the ceramic fiber tube in an embodiment of the present application.

[0034] Figure 6 The electron microscope image of the internal fiber cotton mesh structure of the ceramic fiber tube in an embodiment of the present application.

[0035] Figure 7 The microscope image of the distribution of the catalyst on the surface of the fiber cotton in an embodiment of the present application.

[0036] Figure 8 The experimental data curve of the removal efficiency of the ceramic fiber tube in an embodiment of the present application under different high-concentration pollutants and different temperatures.

[0037] Reference signs: 11, denitration zone; 12, CO removal zone. DETAILED DESCRIPTION

[0038] In order to make the objects, technical solutions and advantages of the present application clearer, the present application is further described in detail below in combination with embodiments and drawings. Herein, the illustrative embodiments of the present application and the descriptions thereof are used to explain the present application, but are not intended to limit the present application.

[0039] It should be noted that, in order not to obscure the present application with unnecessary details, only the structures and / or processing steps closely related to the solution according to the present application are shown in the drawings, while other details not closely related to the present application are omitted.

[0040] It should be emphasized that the term "comprises / comprising" when used in this text refers to the presence of the features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components.

[0041] It should be noted that, in this text, the term "connected" can refer not only to direct connection, but also to indirect connection with the presence of an intermediate.

[0042] In the following, embodiments of the present application will be described with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or similar parts or the same or similar steps.

[0043] In order to solve the various problems of industrial waste gas CO processing in the prior art, and in order to realize the CO processing function of the ceramic fiber pipe, the present application creatively proposes a ceramic fiber pipe and a preparation method thereof, which divides the functional area of the ceramic fiber pipe, and at least greatly improves the CO processing capacity of the industrial waste gas.

[0044] In a first aspect, the present application provides a ceramic fiber pipe, such as Figure 1 As shown, the ceramic fiber pipe includes a flange and a pipe body, the pipe body is open at the flange end for outputting clean flue gas filtered by the pipe body and catalytically treated, and the other end of the pipe body is closed. The pipe body has a plurality of layers of fiber filter paper layers formed by layering fabric made of fiber cotton, it can be understood that the fiber cotton is ceramic fiber, and the slurry is centrifuged and layered to form a pipe body with certain strength. The layered structure of the pipe body can refer to the product cross-section photo of the ceramic fiber pipe shown in Figure 5 As shown, the product cross-section photo of the ceramic fiber pipe can show that the pipe body of the ceramic fiber pipe has a layer-by-layer stacked fiber filter paper layer structure.

[0045] Further, as shown in Figure 2 or Figure 3 Further, the denitration zone 11 includes a layer-by-layer stacked fiber filter paper layer, and the CO removal zone 12 includes b layer-by-layer stacked fiber filter paper layers, wherein a+b≥100. In the embodiment of the present application, each layer of fiber filter paper layer of the pipe body can provide a large specific surface area for loading various catalysts, such as denitration catalyst, CO oxidation catalyst, etc., and the total effective catalytic / adsorption area is increased by several orders of magnitude by stacking hundreds of layers. Referring to Figure 6, the flue gas path becomes extremely tortuous when it flows through the hundreds of layers of complex nano-scale fiber network, greatly extending the contact time between flue gas and catalytically active sites / adsorption sites; this design significantly improves the reaction efficiency and conversion rate of denitration (NOx reduction) and CO oxidation.

[0046] In the above embodiment, the denitration zone 11 and the CO removal zone 12 are partitioned and arranged, allowing independent optimization in the two zones; for example, the denitration catalyst most suitable for the SCR reaction can be loaded on the fibers in the denitration zone 11, and a high-activity CO catalyst can be loaded in the CO removal zone 12, avoiding mutual interference or deactivation between different catalysts. Further, the fiber density, porosity, and layer thickness of each zone can also be adjusted according to the reaction requirements. For example, the denitration reaction may require longer contact time, and a thicker or smaller-pored denitration zone 11 can be designed; the CO oxidation reaction is faster, and a relatively thinner or slightly larger-pored CO removal zone 12 can be designed to reduce the pressure drop. Alternatively, within the denitration zone 11 or the CO removal zone 12, a physical or chemical property gradient (such as porosity decreasing, catalyst concentration gradient) from the inlet to the outlet can also be achieved to match the pollutant concentration changes and reaction kinetics requirements in the reaction process, achieving the most efficient resource utilization and purification effect.

[0047] Further, the pipe body is stacked between adjacent layers of fiber filter paper layers to form nano-scale pores with a pore size of 10-50 nm. More specifically, referring to Figure 6 The hundreds of layers of fiber network form an extremely complex three-dimensional pore structure to ensure that the pore size is within the above range. The nano-scale pores enable particulate matter (especially sub-micron fine particulate matter PM2.5 / PM1) to be efficiently captured by various mechanisms such as inertial collision, interception, diffusion, and electrostatic attraction when flowing through the layers of fibers, with a much higher filtration efficiency than the simple structure of existing ceramic pipes. The multi-layer structure can effectively disperse the airflow, reduce channeling, and make the flue gas flow more uniformly through the entire filtration / catalysis area, fully utilizing all active surfaces.

[0048] The conventional fiber filter tube in the prior art mainly relies on micron-sized pores (>1 pm) to intercept larger particles, and the capture efficiency of PM1 (<1 pm) or even nano-sized particulate matter (such as oil fume, metal aerosol, carbon black) is limited. Compared with the conventional fiber filter tube, the 10-50 nm interlayer pore in the embodiment of the present application precisely covers the "most easily penetrated particle size" interval of the most difficult to filter PM0.1-PM0.5 (100-500 nm) ultrafine particulate matter. When the pollutant nanoparticles move in the 10-50 nm narrow pore, the probability of collision with the fiber surface increases exponentially due to the strong Brownian motion caused by gas molecule impact. If the fiber or the catalyst loaded is charged, the electrostatic force field is stronger in the nano-sized narrow space, which can efficiently attract the charged ultrafine particles; the capture efficiency of the ceramic fiber tube in the embodiment of the present application for PM0.1 or more particulate matter can reach more than 99.9%, achieving near-zero emission or theoretically achieving zero emission.

[0049] Further, the denitration zone 11 at least further comprises a denitration catalyst loaded in the pores and on the surface of the fiber filter paper layer, and the CO removal zone 12 at least further comprises a nano-sized CO catalyst loaded in the pores and on the surface of the fiber cotton. Figure 6 and Figure 7 (the protruding parts marked as 1-8 are catalysts / catalytically active sites attached to the surface of the fiber cotton), the micron-sized fiber spacing and the huge surface area greatly promote the diffusion mass transfer rate of pollutant molecules and the like from the gas phase to the fiber surface catalytically active sites, greatly improving the catalytic reaction efficiency.

[0050] In the above embodiment, the ceramic fiber tube structure formed by stacking the fiber filter paper layers of more than one hundred layers significantly improves the mechanical strength, rigidity and thermal shock resistance of the whole tube body, which can withstand the pressure difference fluctuation, airflow scouring in the operation of the flue gas system and the temperature change in the start-stop process, reduces the risk of cracking, deformation or collapse, and prolongs the service life.

[0051] In the above embodiment, under the synergistic design of the structure of the one hundred layers of fiber filter paper layers and the 10-50 nm interlayer nanopores, by nano-sized loading of the CO catalyst (such as Pt / Pd nanoclusters, CuO-MnO2 composite oxides, etc.) on the surface of the fiber and in the pores, the removal capacity of the ceramic fiber tube for CO has achieved a qualitative leap. The ceramic fiber tube realizes three-dimensional loading of the catalyst on the surface of the fiber cotton and in the pores, greatly improving the active site density; the ceramic fiber tube can embed 2-5 nm platinum nanoparticles into the pore inner wall, which can avoid the self-plugging phenomenon; the 10-50 nm pore setting can force the flue gas carrying pollutants to diffuse along the inner wall, greatly improving the collision frequency of pollutant molecules and the catalyst.

[0052] To further explain the reaction rate multiplication mechanism, taking the chemical reaction process of CO as an example, when CO and O2 are confined in a 10-50 nm pore, the mean free path of the molecules is compressed from the micron level to the nanometer level, the collision frequency of CO molecules in the pore is increased from 10 9 times per second to 10 12 times per second; the adsorption selectivity of the nanopore to O2 is higher than that to CO, an oxygen-rich microenvironment is formed on the surface of the catalyst, and local oxygen concentration polarization is achieved; the confined space can enhance the vibration energy of the Pt-CO bond, so that the activation energy is reduced from 80 kJ / mol to 50 kJ / m, and the apparent activation energy is reduced. The above examples can also reduce the CO light-off temperature, and realize the low-temperature route. The ceramic fiber filter tube can be suitable for high-concentration CO (such as 10000 mg / Nm3) flue gas treatment in the sintering link of the steel industry.

[0053] In the above examples, the present application can realize the synergistic treatment of multiple pollutants (such as dust, SO2, CO, NOx, HCl, HC, dioxin and VOCs, etc.) by the layered layout of the CO removal zone 12 and the denitration zone 11 on the pipe body, and by the filtering effect of the outer wall of the pipe body on dust and desulfurizing agent or adsorbent. It can also avoid mutual interference caused by mixed functions.

[0054] The present application makes full use of the characteristics of high specific surface area, high temperature resistance and processability into complex shapes of ceramic fiber materials, and is particularly suitable for high-end flue gas treatment application scenarios that require deep purification, high removal efficiency, treatment of complex pollutants and harsh working conditions (such as high temperature, high dust and corrosive atmosphere).

[0055] It can be understood that the above desulfurizing agent or adsorbent can be lime or bicarbonate, and the desulfurizing agent or adsorbent that reacts with SO2 is filtered through the outer wall of the pipe body, that is, the outer wall of the pipe body realizes the desulfurization bed or dust collection effect. The pollutant reaction process that can be treated by the desulfurizing agent or adsorbent is as follows:

[0056] SO2+Ca(OH)2=CaSO3+H2O

[0057] CaSO3+½O2=CaSO4

[0058] SO3+Ca(OH)2=CaSO4+H2O

[0059] 2HCl+Ca(OH)2=CaCl2+H2O

[0060] 2HF+Ca(OH)2=CaF2+2H2O

[0061] The denitration is achieved by using NH3 or urea as a reducing agent when passing through the denitration zone 11 of the pipe body. When the flue gas passes through the denitration zone 11, the denitration reaction is carried out under the action of the denitration catalyst, the removal rate is high, and the NH3 escape efficiency is low. The denitration reaction principle is as follows:

[0062] 4NO + 4NH3 + O2 = 4N2 + 6H2O

[0063] 2NO2 + 4NH3 + O2 = 3N2 + 6H2O

[0064] According to the actual situation, the distribution order and position of the denitration zone 11 and the CO removal zone 12 of the ceramic fiber pipe in the embodiment of the application can have various embodiments to adapt to different application scenarios.

[0065] Example 1

[0066] As shown in Figure 2 , the denitration zone 11 is located on the outer layer of the pipe body, and the CO removal zone 12 is located on the inner layer of the pipe body. In this embodiment, the application is reconstructed by “desulfurization-denitration-CO removal” partition, which strengthens the sulfur protection and heat utilization. Among them, the adsorbent dust collection effect realized by the outer wall of the pipe body preferentially removes SO2, avoids the sulfates from entering the denitration catalyst (such as V2O5-WO3 / TiO2) or CO catalyst (such as Pt / Al2O3) in the denitration zone 11, and can prolong the service life of the overall filter pipe. The high-temperature waste gas (such as steel sintering flue gas with a temperature of 300-400℃) enters the denitration zone 11 on the outer layer, and the required temperature (180-400℃) for the denitration reaction, while the inner layer CO catalytic combustion (such as 250-350℃) can be naturally maintained by waste heat, reducing the external heating energy consumption. N2 and H2O generated in the denitration zone 11 can dilute the CO concentration, reducing the explosion risk of the inner layer CO catalytic combustion. The NH3 not completely consumed in the denitration reaction can participate in the CO catalytic oxidation (such as 4CO + 2NO + 4NH3→ 4CO2+ 3N2+ 6H2O), which improves the cooperative removal rate of nitrogen oxides and CO. The layered arrangement of the pipe body in this embodiment can be applied to the treatment of high-dust, high-sulfur and high-temperature flue gas in coal-fired power plants, and the treatment of flue gas containing heavy metal dust and dioxin precursors in waste incinerators.

[0067] Example 2

[0068] As shown in Figure 3As shown, the CO removal zone 12 is located on the outer layer of the pipe body, and the denitrification zone 11 is located on the inner layer of the pipe body. In this embodiment, the Pt-based CO catalyst in the CO removal zone 12 can initiate CO oxidation at a relatively low temperature at the flue gas inlet, solving the problem of low denitrification efficiency under low-temperature conditions; the heat released during the CO oxidation and combustion removal process can heat the flue gas, thus achieving the preheating function of the flue gas and activating the catalytic effect of the inner denitrification zone 11. If sulfides are reacted by the desulfurizing agent or adsorbent, dust filtration and adsorption can be achieved on the outer wall of the pipe body; protecting the subsequent CO catalyst from poisoning; removing CO first can prevent CO from competing with NH3 (denitrification reducing agent) for adsorption on the catalyst in the denitrification zone 11, thereby improving the denitrification efficiency. The layered pipe body configuration of this embodiment is applicable to the treatment of low-temperature, high-CO-concentration flue gas in the steel sintering industry, and also to the treatment of flue gas containing large molecules such as tar in coking plant tail gas.

[0069] Example 3

[0070] like Figure 4 As shown, the denitrification zone 11 and the CO removal zone 12 are completely overlapped. Optionally, all of the more than one hundred layers of fiber filter paper are loaded with denitrification catalyst and CO catalyst. Each layer of fiber filter paper provides denitrification and CO catalytic sites, which can significantly shorten the reaction path and achieve a "NOx reduction-CO oxidation" relay reaction within the nanoscale pores, greatly improving the treatment effect. Optionally, the active component CeO2 carrier can not only provide oxygen vacancies for SCR, but also protect the CO catalyst from sulfur poisoning. This arrangement can reduce the resistance at the functional zone interface and reduce pressure drop. The pipe structure of this embodiment is applicable to compact flue gas treatment systems such as clean flue gas treatment for natural gas boilers and ship exhaust gas treatment.

[0071] Optionally, the denitrification zone 11 and the CO removal zone 12 are configured to at least partially overlap, with the denitrification catalyst and the CO catalyst loaded within the fiber filter paper layer in the overlapping area. This invention explores a new pathway for the synergistic treatment of multiple pollutants through the partial or complete overlap design of the denitrification zone 11 and the CO removal zone 12. The partial overlap of the denitrification zone 11 (SCR) and the CO removal zone 12, utilizing the oxidizing properties of the denitrification catalyst (such as V2O5-WO3 / TiO2), may promote the synergistic removal of CO and NOx (e.g., 4CO + 2NO2 → 4CO2 + N2), theoretically increasing the conversion efficiency by 10%~20%. The heat released from the catalytic combustion of CO (250~350℃) can provide temperature compensation for the denitrification reaction in the overlapping zone, which is particularly suitable for low-temperature exhaust gas scenarios and can reduce external heating energy consumption.

[0072] In some embodiments, the tube body in the present application can be configured with a wall thickness of about 20 mm, such as ± 2 mm. The thickness of each layer of fibrous filter paper layer is about 0.1-0.3 mm, and the centrifugal cloth process can precisely control the porosity of each layer of fibrous filter paper layer to achieve a balance between high throughput and high trapping efficiency.

[0073] Alternatively, the total wall thickness of the tube body is 18-21 mm, the thickness of the denitration zone 11 is configured to be no less than 2 / 3 of the total wall thickness, and the thickness of the CO removal zone 12 is configured to be no less than 1 / 3 of the total wall thickness; or it can also be designed that the number of fibrous filter paper layers of the denitration zone 11 is configured to be no less than 2 / 3 of the total number of fibrous filter paper layers of the tube body, and the number of fibrous filter paper layers of the CO removal zone 12 is configured to be no less than 1 / 3 of the total number of fibrous filter paper layers of the tube body. This design makes the ceramic fibrous filter tube have the thickness or number of layers advantage of the denitration zone 11, which can ensure high processing efficiency even if the denitration reaction is slow, and through the high-efficiency catalytic action of the CO removal zone 12 with less thickness or number of layers, low-temperature instantaneous purification of CO can be achieved.

[0074] In addition, the ceramic fibrous tube in the embodiments of the present application has a honeycomb-like network formed by nano-pores, which increases the specific surface area of the ceramic fiber to 300-500 m² / g (only 50-100 m² / g for traditional micropores), greatly increases the loading density of the CO catalyst, and increases the CO oxidation reaction rate to several times that of traditional filter tubes. The three-dimensional interconnected network formed by nano-pores can anchor the CO catalyst and inhibit migration and agglomeration at high temperatures. The capillary action of nano-pores can promote the rapid desorption of reaction products (such as CO2), reducing carbon deposition.

[0075] In some embodiments, the pores in the tube body of the ceramic fibrous tube are asymmetric gradient pores, the pore size of the nano-pores gradually increases in the direction from the outside to the inside, so that the resistance gradually decreases when the flue gas flows from the outside to the inside; this design is also different from existing ceramic tubes, overcoming the problem of excessive pressure drop caused by deep filtration of large wall thickness ceramic tubes.

[0076] Alternatively, the porosity of the tube body is ≥80%, and the porosity gradually increases in the direction from the outside to the inside. The high porosity design can provide growth space for the CO catalyst, and the number of catalytic active sites is greatly increased. In this embodiment, the combination of the double gradient change design of pore size and porosity can reduce the pressure drop and be suitable for high flow rate flue gas treatment; the service life of the ceramic fibrous tube is greatly improved; and the design can also realize low-temperature purification.

[0077] In some embodiments, the pipe body is a multi-layered fiber filter paper layer structure with nano-scale pores formed by centrifugal distribution of slurry configured by Al2O3 / SiO2 ceramic fibers and auxiliary materials, and the diameter of the Al2O3 / SiO2 ceramic fibers is 3-5 μm. The Al2O3 / SiO2 ceramic fibers can withstand high temperature above 1200°C (softening point > 1600°C), and are suitable for high-heat waste gas scenes such as glass melting furnace and steel sintering. The ceramic fiber pipe made of Al2O3 / SiO2 ceramic fibers has excellent corrosion resistance in the pH range of 3-11, and can resist acid (such as SO2 and HCl) and alkaline (such as NH3) gas erosion, and the service life is more than 50% higher than that of ordinary aluminum silicate fiber. The specific surface area of 3-5 μm fibers, such as 4 μm fibers, can reach 357 m 2 / g, which greatly improves the specific surface area and also realizes efficient capture of nanoparticles. SiO2 can provide Bronsted acid sites, and Al2O3 can provide Lewis acid sites, both of which can synergistically promote the SCR denitration reaction. The selected ratio of Al2O3 and SiO2 ceramic fibers can be set according to actual needs.

[0078] In some embodiments, the CO catalyst includes at least one of a Pd-based catalyst, a Pt-based catalyst, a copper-based catalyst, a cobalt-molybdenum-based catalyst, an iron-based catalyst, and a nitrogen-doped graphene catalyst. Among them, the Pd-based catalyst can use Pd-Cu / hydroxyapatite (HAP) catalyst and palladium gold series catalysts, etc. The Pt-based catalyst can use Pt / Al2O3. The copper-based catalyst can use Cu-Zn system catalyst, Fe-Cr system catalyst, and conventional copper oxide-manganese dioxide catalyst, etc.

[0079] In some embodiments, the denitration catalyst includes at least V2O5, TiO2, and CeO2. Among them, the V-Ti system is the main catalyst for SCR denitration, TiO2 can provide high specific surface area (> 80 m 2 / g) and sulfur resistance. CeO2 adjusts the oxidation-reduction cycle through oxygen storage capacity (OSC), promotes SO2→SO3 conversion, and inhibits sulfate deposition, solving the problem of sulfur poisoning.

[0080] In some embodiments, the CO catalyst includes Pt, and the denitration zone 11 further includes V2O5, TiO2, and CeO2 impregnated in the pores, and the mass ratio of the Pt, V2O5, TiO2, and CeO2 is 0.1-0.5wt%, 22.4-23.7wt%, 67.1-71.2wt%, and 5-10wt%, respectively. In this formula, Pt catalyzes CO at low temperature, V-Ti system denitrates, and CeO2 resists sulfur, and the three are gradiently distributed to form a complementary function, realizing efficient combination and use of multi-effect catalysts.

[0081] In some embodiments, the CO catalyst comprises Pt, the denitration catalyst comprises V2O5, TiO2 and CeO2, the pipe body is further loaded with WO3 and MnO2; the mass proportions of the Pt, Pt, V2O5, TiO2, CeO2, WO3 and MnO2 are 0.1-0.5 wt%, 22.4-23.7 wt%, 67.1-71.2 wt%, 5-10 wt%, 1.5-2.5 wt%, 1.5-2.5 wt% respectively. In this formula, Pt catalyzes CO at low temperature, V-Ti system denitrates, CeO2 is resistant to sulfur, WO3 can greatly improve the SCR reaction speed and reduce the light-off temperature; MnO2 can realize low-temperature oxidation of CO and protect Pt from poisoning by sulfides.

[0082] In a second aspect, the application further provides a preparation method of the ceramic fiber pipe, the thickness of the denitration zone 11 is equal to the total wall thickness of the pipe body, and the CO removal zone 12 is located in the inner layer of the pipe body and has a thickness equal to 1 / 3 of the total wall thickness of the pipe body, and the method comprises the following steps:

[0083] After the pipe body of the ceramic fiber pipe is prepared, a nano-impregnation solution containing a denitration catalyst is used to realize gradient concentration loading of the denitration catalyst in the entire pipe wall thickness direction of the pipe body by adopting a directional impregnation process from inside to outside; during the impregnation of the denitration catalyst, the drying temperature of the outer layer of the pipe body is controlled to be higher than that of the inner layer, so that the evaporation amount of the nano-impregnation solution of the outer layer is large to form migration and loading of the denitration catalyst, and the concentration of the denitration catalyst gradually decreases in the direction from outside to inside.

[0084] After the loading of the denitration catalyst is completed, a nano-impregnation solution containing a CO catalyst is used to realize gradient concentration loading of the CO catalyst in the inner 1 / 3 pipe wall by adopting a directional impregnation process from inside to outside.

[0085] In this embodiment, the preparation method of the ceramic fiber pipe realizes precise spatial gradient distribution of the catalyst while maintaining the simplicity of the process through the innovative design of “full-wall denitration gradient + CO local enrichment”; the denitration catalyst has the maximum concentration at the outer layer position of the pipe body, so that the active sites in the flue gas inlet area are greatly improved, and the catalyst usage can be reduced. The CO catalyst generally uses noble metals and is limited in the inner layer area of the pipe body, which is economical and can also avoid deactivation due to high-temperature sintering or poisoning by sulfides in the outer layer. The method realizes full-wall denitration gradient and inner layer CO catalyst gradient through double impregnation and temperature field regulation without complex masking.

[0086] In a third aspect, the application further provides a preparation method of the ceramic fiber pipe, the denitration zone 11 is located in the outer layer of the pipe body and has a thickness equal to 2 / 3 of the total wall thickness of the pipe body, and the CO removal zone 12 is located in the inner layer of the pipe body and has a thickness equal to 1 / 3 of the total wall thickness of the pipe body, and the method comprises the following steps:

[0087] After the pipe body of the ceramic fiber pipe is prepared, a nano-impregnation solution containing a denitration catalyst is used to realize gradient concentration loading of the denitration catalyst in the outer 2 / 3 total wall thickness of the pipe body by adopting an outside-in directional impregnation process; the denitration catalyst is impregnated from outside to inside, which can realize the effect of high concentration outside and low concentration inside of the denitration catalyst to match the concentration decay of NOx in flue gas.

[0088] A nano-impregnation solution containing a CO catalyst is used to realize gradient concentration loading of the CO catalyst in the inner 1 / 3 pipe wall of the pipe body by adopting an inside-out directional impregnation process. The impregnation of the CO catalyst from inside to outside can be distinguished from the impregnation process of the denitration catalyst.

[0089] In this embodiment, the method realizes the spatial precise distribution of the denitration zone 11 and the CO zone catalyst by the process design of bidirectional countercurrent gradient impregnation of the denitration catalyst and the CO catalyst respectively; the concentration configuration of the denitration catalyst is high outside and low inside, which can match the NOx decay kinetics, and the concentration configuration of the CO catalyst is high inside and low outside, which can adapt to the reaction heat release temperature field and improve the CO oxidation removal efficiency. The method can solve the problems of catalyst waste, cross contamination and pore blockage in the traditional process, and is especially suitable for complex flue gas scenes with high dust, high sulfur and high CO, and provides a manufacturing paradigm with high performance and low cost for near-zero emission.

[0090] In the foregoing two preparation methods, after the pipe body of the ceramic fiber pipe is prepared, a nano-impregnation solution containing a denitration catalyst is used to realize gradient concentration loading of the denitration catalyst in the outer 2 / 3 total wall thickness of the pipe body by adopting an outside-in directional impregnation process; the denitration catalyst is impregnated from outside to inside, which can realize the effect of high concentration outside and low concentration inside of the denitration catalyst to match the concentration decay of NOx in flue gas. 2 / g, laser particle detection data Dv(50) is between 0.075-0.1 μm, and Dv(99) <1.0 μm, a nano-impregnation solution containing chloroplatinic acid, ammonium metavanadate, titanium dioxide and cerium dioxide, is used to realize uniform loading of active components by adopting a directional impregnation process, and an external negative pressure of the filter pipe or an internal positive pressure of the filter pipe is used to assist penetration, so that the internal and external pressure difference is 0.05~0.1 MP; after sufficient impregnation, gradient drying at 60~100℃ is performed.

[0091] Alternatively, the pipe body of the ceramic fiber pipe can be prepared by a silica sol-ceramic fiber slurry, the silica sol is used as a binder to form nanoscale pores in the centrifugal distribution process, avoid the closed pore problem caused by traditional extrusion molding, and the pore distribution is uniform. The catalyst precursor in the nano-impregnation solution is loaded on the nano-TiO2 carrier to form a mesoporous network structure by a sol-gel method, and the pore size can be 2-8 nm.

[0092] Alternatively, chloroplatinic acid (H2PtCl6) is a Pt precursor, which can provide Pt active sites to catalyze low-temperature oxidation of CO. H2PtCl6·6H2O is dissolved in dilute hydrochloric acid (pH=2-3), and the concentration is controlled to be 0.01-0.05 mol / L. Chloroplatinic acid (H2PtCl6) has high dispersity and can provide a super-high active surface.

[0093] Optionally, ammonium metavanadate (NH4VO3) is the precursor of V2O5, which is the main active phase of De-NOx (SCR) and cooperates with TiO2. V2O5 is uniformly dispersed on the surface of TiO2. NH4VO3 is dissolved in ammonia water (pH = 8-9), and heated to 60°C to promote dissolution and avoid the formation of precipitates.

[0094] Optionally, titanium dioxide (TiO2) provides a high specific surface area (> 80 m 2 / g) to support the active layer. Sol-gel or hydrothermal synthesis can be used to prepare high specific surface area anatase TiO2 (e.g., specific surface area > 80 m 2 / g, pore size 5-10 nm).

[0095] Optionally, cerium dioxide (CeO2) is an oxygen storage aid that can resist sulfur poisoning and is used to regulate the redox cycle. CeO2 nanoparticles (particle size 30-50 nm) can be synthesized by the precipitation-calcination method and ultrasonically dispersed in deionized water.

[0096] Optionally, the four are mixed in proportion (Pt:V:Ti:Ce = 0.1-0.5:22.4-23.7:67.1-71.2:5-10), a dispersant (such as polyethylene glycol PEG-4000) is added, and magnetic stirring is performed for 2 hours. Further, to avoid agglomeration, an ultrasonic disrupter (power 500 W, frequency 20 kHz) is used for 30 minutes to break up the particle agglomeration. The pH of the mixture is adjusted to 4-5 (with acetic acid) to enhance the surface zeta potential of the nanoparticles (absolute value > 30 mV) to prevent settling.

[0097] Optionally, the particle size distribution in the nano-impregnation solution is configured as Dv(50) = 0.075-0.1 μm and Dv(99) < 1.0 μm, and high-pressure homogenization combined with ultrasonic cavitation can be used to control the particle distribution. Dv(50) is configured as 75-100 nm to match the 10-50 nm gap between ceramic fibers; Dv(99) is configured as less than 1000 nm to prevent clogging of the capillary channels or nano-scale pores.

[0098] Optionally, the impregnation solution is allowed to penetrate from the inner wall to the outer wall of the ceramic fiber pipe or from the outer wall to the inner wall by negative pressure suction, and the active components (Pt, V2O5) are preferentially enriched in the inner layer, and CeO2 is dispersed outward in a gradient, forming an "inner catalysis-outer protection" structure. The pore size of the carrier matches the particle size of the impregnation solution to ensure that the active components are anchored on the surface of the pores and avoid clogging.

[0099] Optionally, the gradient drying process can be configured as: drying at 60℃ for 2h→drying at 80℃ for 2h→drying at 100℃ for 1h, gradually removing moisture to prevent capillary force from destroying the pore structure. After gradient drying, the pipe body can also be calcined and activated, such as calcining at 350℃ for 2h (air atmosphere), so that NH4VO3 is decomposed into V2O5, and H2PtCl6 is reduced into Pt nanoparticles, so that the particle size is 2-5nm.

[0100]

[0101] The preparation method in the embodiment of the present application can match the nanopores with the particles to maximize the exposure of active sites; the directional impregnation and gradient drying process can avoid structural collapse and ensure long-term stability of the structure.

[0102] In the present application, the ceramic fiber pipe prepared by the above preparation method is experimentally verified under different temperatures and different CO and NOx concentration conditions. The experimental scene focuses on the flue gas of the sintering link in the steel industry, for example, the original concentration of CO in the sintering machine head exhaust is usually 5000-10000mg / m 3 , the original concentration of NOx is generally 200-600mg / m 3 , which belongs to high-concentration pollutant flue gas.

[0103] Combining Figure 8 and the following table content, it can be seen that the CO removal efficiency is higher at the starting point of 200℃, reaching 75.0%, and then steadily rising, entering the high-efficiency platform (removal efficiency > 85%) at about 240℃, and approaching saturation after about 280℃, and achieving high-temperature stability at about 300℃. The NOx removal rate is better than that of CO, maintaining high-efficiency removal efficiency throughout the temperature range of 180℃-320℃, with a removal rate of 97.1% at 295℃. The data prove that the ceramic fiber pipe can also be used in the low-temperature section (180℃-240℃), with a CO removal rate of ≥60.3% and a NOx removal rate of ≥75.2% for high-concentration pollutant flue gas. This temperature section is completely suitable for the treatment of low-concentration pollutants. The ceramic fiber pipe has excellent performance in the medium-temperature section (240℃-320℃), with a CO removal rate of ≥85.1% and a NOx removal rate of ≥92.3%.

[0104] In a fourth aspect, the application further provides a use of the ceramic fiber pipe in the synergistic purification of CO, HC, VOCs and NOx in industrial waste gas, and the operating temperature is 180-320 DEG C. The ceramic fiber pipe can not only efficiently remove CO in the waste gas, but also simultaneously treat harmful substances such as HC, VOCs, NOx and dioxin. The synergistic purification feature makes the filter pipe have a wide application potential in the treatment of industrial waste gas, especially when multiple pollutants need to be removed simultaneously in a complex waste gas source.

[0105] The ceramic fiber pipe of the application promotes the oxidation reaction of CO by the catalyst in the CO removal zone 12, converts it into carbon dioxide (CO2), and achieves the purpose of efficiently removing CO. VOCs (volatile organic compounds) are another important pollutant in industrial waste gas. The catalytic material in the ceramic fiber pipe can promote the oxidation reaction of VOCs, which is converted into harmless substances (such as water and carbon dioxide). The denitration catalyst in the filter pipe can remove NOx by selective catalytic reduction reaction, which is converted into nitrogen and water vapor. Due to the stability of the filter pipe at high temperature, it can be operated for a long time in a high-temperature industrial environment and maintain its filtering and catalytic performance. High-temperature conditions help to maintain the activity of the catalyst, and also accelerate the oxidation reaction of CO and VOCs, thereby improving the purification efficiency. Through experiments, it is verified that the ceramic fiber pipe realizes strong oxidation degradation of CO, HC and VOCs and efficient reduction of NOx in the range of 240-320 DEG C, the CO removal rate is greater than or equal to 85%, and the NOx removal rate is greater than or equal to 92%, which is suitable for the synergistic purification of multiple pollutants in complex flue gas in the steel and coking industries.

[0106] It should be noted that the application is not limited to the specific arrangements and processes described above and shown in the drawings. For the sake of brevity, detailed descriptions of well-known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the application is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order of the steps, after understanding the spirit of the application.

[0107] In the application, the features described and / or exemplified for one embodiment can be used in the same way or in a similar way in one or more other embodiments, and / or in combination with or instead of the features of other embodiments.

[0108] The above description is only the preferred embodiments of the application and is not intended to limit the application. Those skilled in the art can make various changes and modifications to the embodiments of the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A ceramic fiber pipe, characterized by, The ceramic fiber pipe has a pipe body with multiple layers of fiber filter paper formed by layering fiber cotton through a centrifugal distribution process, the pipe body including a denitration zone and a CO removal zone arranged along a wall thickness direction; The denitration zone includes a layer of fiber filter paper, and the CO removal zone includes b layers of fiber filter paper, wherein a+b≥100; The pipe body has nanoscale pores between adjacent layers of fiber filter paper, the nanoscale pores having a pore size of 10-50 nm; the nanoscale pores are asymmetric gradient pores, the pore size of the nanoscale pores gradually increases in a direction from outside to inside, so that the resistance gradually decreases when flue gas flows from outside to inside; The denitration zone further includes a denitration catalyst loaded in the nanoscale pores and on the surface of the fiber filter paper, and the CO removal zone further includes a CO catalyst loaded in the nanoscale pores and on the surface of the fiber cotton.

2. The ceramic fiber tube of claim 1, wherein, The denitration zone is located at an outer layer of the pipe body, and the CO removal zone is located at an inner layer of the pipe body; or The CO removal zone is located at an outer layer of the pipe body, and the denitration zone is located at an inner layer of the pipe body.

3. The ceramic fiber tube according to claim 1 or 2, characterized in that, The denitration zone and the CO removal zone are arranged at least partially overlapping, and the denitration catalyst and the CO catalyst are loaded in the fiber filter paper in the overlapping region.

4. The ceramic fiber tube of claim 3, wherein, The total wall thickness of the pipe body is 18-21 mm, the thickness of the denitration zone is configured to be not less than 2 / 3 of the total wall thickness, and the thickness of the CO removal zone is configured to be not less than 1 / 3 of the total wall thickness; or The number of layers of fiber filter paper in the denitration zone is configured to be not less than 2 / 3 of the total number of layers of fiber filter paper in the pipe body, and the number of layers of fiber filter paper in the CO removal zone is configured to be not less than 1 / 3 of the total number of layers of fiber filter paper in the pipe body.

5. The ceramic fiber tube of claim 3, wherein, The porosity of the pipe body is ≥80%, and the porosity gradually increases in a direction from outside to inside.

6. The ceramic fibrous pipe of claim 1, wherein, The pipe body is a multi-layer fiber filter paper structure with nanoscale pores formed by centrifugal distribution of a slurry configured from Al2O3 / SiO2 ceramic fibers and auxiliary materials, and the diameter of the Al2O3 / SiO2 ceramic fibers is 3-5 μm.

7. The ceramic fibrous pipe of claim 1, wherein The CO catalyst includes at least one of a Pd-based catalyst, a Pt-based catalyst, a copper-based catalyst, a cobalt-molybdenum-based catalyst, an iron-based catalyst, and a nitrogen-doped graphene catalyst.

8. The ceramic fibrous pipe of claim 1, wherein, The denitration catalyst includes at least V2O5, TiO2, and CeO2.

9. The ceramic fibrous pipe of claim 1, wherein, The CO catalyst includes Pt, the denitration catalyst includes V2O5, TiO2, and CeO2, and the mass proportions of the Pt, V2O5, TiO2, and CeO2 are 0.1-0.5 wt%, 22.4-23.7 wt%, 67.1-71.2 wt%, and 5-10 wt%, respectively; or The CO catalyst comprises Pt, the denitration catalyst comprises V2O5, TiO2 and CeO2, the pipe body is further loaded with WO3 and MnO2; the mass proportions of the Pt, V2O5, TiO2, CeO2, WO3 and MnO2 are 0.1-0.5 wt%, 22.4-23.7 wt%, 67.1-71.2 wt%, 5-10 wt%, 1.5-2.5 wt% and 1.5-2.5 wt% respectively.

10. A method of producing the ceramic fiber tube as claimed in any one of claims 1 to 9, characterized by, The thickness of the denitration zone is configured to be equal to the total wall thickness of the pipe body; the CO removal zone is located at the inner layer of the pipe body, and the thickness thereof is configured to be equal to 1 / 3 of the total wall thickness of the pipe body; and the method comprises the following steps: After the pipe body of the ceramic fiber pipe is prepared, a nano-impregnation solution containing the denitration catalyst is used, and a directional impregnation process from the outside to the inside is adopted to realize gradient concentration loading of the denitration catalyst in the entire pipe wall thickness direction of the pipe body; during the impregnation of the denitration catalyst, the drying temperature of the outer layer of the pipe body is controlled to be higher than that of the inner layer, so that the evaporation amount of the nano-impregnation solution of the outer layer is large, and migration and loading of the denitration catalyst are formed, so that the concentration of the denitration catalyst gradually decreases in the direction from the outside to the inside; After the loading of the denitration catalyst is completed, a nano-impregnation solution containing the CO catalyst is used, and a directional impregnation process from the inside to the outside is adopted to realize gradient concentration loading of the CO catalyst in the inner 1 / 3 pipe wall.

11. A method of producing the ceramic fiber tube as claimed in any one of claims 1 to 9, characterized by, The denitration zone is located at the outer layer of the pipe body, and the thickness thereof is equal to 2 / 3 of the total wall thickness of the pipe body; the CO removal zone is located at the inner layer of the pipe body, and the thickness thereof is equal to 1 / 3 of the total wall thickness of the pipe body; and the method comprises the following steps: After the pipe body of the ceramic fiber pipe is prepared, a nano-impregnation solution containing the denitration catalyst is used, and a directional impregnation process from the outside to the inside is adopted to realize gradient concentration loading of the denitration catalyst in the outer 2 / 3 total wall thickness of the pipe body; A nano-impregnation solution containing the CO catalyst is used, and a directional impregnation process from the inside to the outside is adopted to realize gradient concentration loading of the CO catalyst in the inner 1 / 3 pipe wall of the pipe body.

12. The production method according to claim 10 or 11, characterized by, The directional impregnation process from the outside to the inside or the directional impregnation process from the inside to the outside adopts negative pressure on the outside of the pipe body or positive pressure on the inside of the pipe body to assist in permeation, so that the pressure difference between the inside and the outside is 0.05-0.1 MP; The specific surface area of the nano-impregnation liquid is > 60 m 2 / g, laser particle detection data Dv(50) is between 0.075-0.1 pm, Dv(99) < 1.0 pm; After the denitration catalyst and the CO catalyst are fully loaded, the pipe body is subjected to gradient drying treatment at 60-100℃.

13. Application of the ceramic fiber pipe according to any one of claims 1-9 in the cooperative purification of CO, HC, VOCs and NOx in industrial waste gas, and the operating temperature is 180-320℃.

Images