Integrated ceramic catalytic filter tube and preparation method and application thereof

Abstract

This invention discloses an integrated ceramic catalytic filter tube, its preparation method, and its application, belonging to the field of industrial flue gas treatment. The integrated ceramic catalytic filter tube includes a ceramic filter tube substrate and a catalytic coating. The raw materials for the catalytic coating include a noble metal catalytic slurry and a vanadium-based catalytic slurry. The noble metal catalytic slurry includes a noble metal catalyst. The noble metal catalyst uses Nb-CeO2 / WO3 as a support and platinum and / or palladium as the active ingredient. The mass ratio between the active ingredient and the support is (0.1–0.15):1. The catalytic coating obtained by combining two different active catalytic slurries can compensate for each other's insufficient activity within different temperature ranges, improving the overall multi-pollutant removal efficiency of the catalytic coating. Furthermore, using a porous ceramic filter tube as the substrate material not only facilitates the distribution of the catalytic slurry but also helps retain particulate pollutants, achieving integrated denitrification and dust removal and efficient treatment of multiple pollutants in flue gas.

Description

Technical Field

[0001] This invention relates to the field of industrial flue gas treatment, and in particular to an integrated ceramic catalytic filter tube, its preparation method, and its application. Background Technology

[0002] Coke is mainly used as fuel and a reducing agent in ironmaking, and it has wide applications in many industries such as metallurgy, casting, chemicals, and energy. my country ranks first in the world in coke production. Coke production, as well as biomass boilers and refractory furnaces in other industries, have a significant impact on the energy structure and can greatly promote the rapid development of my country's industry.

[0003] However, coke production is also accompanied by serious air pollution problems. The flue gas produced by coke ovens and small and medium-sized industrial kilns contains a large amount of conventional and unconventional pollutants such as sulfur dioxide, dust, nitrogen oxides, and non-methane total hydrocarbons. The long-term accumulation of these pollutants in the atmosphere will seriously damage the environment and endanger human life, health and safety. With the increasing emphasis on environmental protection, how to effectively treat these pollutants is of great significance.

[0004] Currently, control measures for various pollutants in coke oven flue gas mainly include source control and end-of-pipe treatment. Source control includes blast furnace gas heating, reducing flue temperature, reducing excess air coefficient, adopting waste gas recirculation and segmented heating technologies, strengthening coke oven heating, and reducing coke oven leakage, etc., to help reduce pollutant generation at the source. End-of-pipe treatment includes desulfurization, denitrification, and dust removal processes. Common flue gas end-of-pipe treatment processes use different equipment to desulfurize, denitrify, and remove dust from the flue gas separately, which is a series treatment process. However, this process method uses many process treatment units, occupies a large area, has a complex process flow, and cumbersome process control. Moreover, there is no relevant equipment capable of treating non-methane total hydrocarbons.

[0005] To address this issue, a dust-nitrogen catalytic filter tube has been proposed for the denitrification and dust removal steps in industrial flue gas. This tube can achieve the synergistic treatment of multiple pollutants in the flue gas. However, the removal efficiency of this treatment method is currently poor, with a low removal rate at low temperatures. Furthermore, it does not effectively remove non-methane total hydrocarbons from the flue gas, and there is no efficient method for treating non-methane total hydrocarbons. Summary of the Invention

[0006] This invention provides an integrated ceramic catalytic filter tube, its preparation method, and its application, which can solve the problems of the difficulty in efficiently and synergistically removing multiple pollutants in industrial flue gas and the lack of efficient methods for treating non-methane total hydrocarbons in the prior art.

[0007] In a first aspect, the present invention provides an integrated ceramic catalytic filter tube, comprising a ceramic filter tube substrate and a catalytic coating; the raw materials for the catalytic coating include precious metal catalytic slurry and vanadium-based catalytic slurry;

[0008] The noble metal catalytic slurry includes a noble metal catalyst; the noble metal catalyst uses Nb-CeO2 / WO3 as a support and platinum and / or palladium as active components; the mass ratio between the active component and the support is (0.1~0.15):1.

[0009] Preferably, the SiO2 content in the ceramic filter tube matrix is ​​40-60%, and the Al2O3 content is 10-30%; the specific surface area of ​​the ceramic filter tube matrix is ​​10-15 m². 2 / g.

[0010] By adopting the above technical solution, the ceramic filter tube of the present invention is composited with a noble metal catalyst and a vanadium-based catalyst. The combination of the two can greatly improve the denitrification efficiency of the catalytic coating. The noble metal active component can exhibit good catalytic activity in the low temperature range and can convert nitrogen oxides into non-toxic nitrogen gas and water. The vanadium-based active component can realize the conversion of pollutants in the medium and high temperature range. In different temperature ranges, different catalysts can compensate for each other's insufficient activity, thereby maintaining a high overall denitrification rate.

[0011] Furthermore, the addition of precious metal catalytic slurry can catalytically remove non-methane total hydrocarbons from industrial flue gas. Non-methane total hydrocarbons refer to all volatile hydrocarbons other than methane, including alkanes, alkenes, aromatic hydrocarbons, etc. Precious metals can effectively adsorb non-methane total hydrocarbons and reduce the activation energy of chemical reactions, dissociating oxygen in the flue gas into active oxygen atoms, which then react and combine with non-methane total hydrocarbon compounds to generate non-toxic peroxides, thereby achieving the catalytic decomposition of non-methane total hydrocarbons.

[0012] Moreover, the catalytic coating of the present invention is composited on the surface of the ceramic filter tube, which has a rich pore structure. On the one hand, the catalytic slurry can be uniformly dispersed in the micropores of the ceramic filter tube, improving catalytic activity and thus increasing the conversion rate of pollutants. On the other hand, the ceramic filter tube itself can also use its pore structure to physically intercept particulate pollutants on the surface or inside of the ceramic filter tube, achieving integrated denitrification and dust removal.

[0013] The ceramic catalytic filter tube obtained by the above composite can promote the synergistic catalytic reaction of multiple pollutants, including non-methane total hydrocarbons, in industrial flue gas, thereby achieving the synergistic removal of multiple pollutants without changing the treatment unit. This not only saves floor space but also reduces operating costs, achieving efficient treatment of multiple pollutants in flue gas.

[0014] However, the flue gas is also rich in a large amount of sulfides. These sulfides are easily attracted by the active components of precious metals, covering the active sites in the precious metal catalytic slurry, thus losing catalytic activity. As a result, the low-temperature removal rate of the obtained ceramic catalytic filter tube is reduced. Moreover, it will work with water vapor to erode the catalytic coating and affect the removal efficiency.

[0015] To improve the water and sulfur resistance of ceramic catalytic filters, the noble metal catalyst in this invention uses Nb-CeO2 / WO3 as a support. The partial substitution of Nb creates oxygen vacancies in the support, which adsorb water molecules and accelerate their dissociation, thus reducing the physical occupancy of water molecules at the active sites of the noble metal catalyst. Furthermore, it promotes the generation of reactive oxygen species at the active sites, inhibiting the conversion of sulfides to sulfates and reducing sulfate coverage of the active sites. Simultaneously, CeO2 is also composited with WO3. The WO3 framework forms a physical barrier, protecting the noble metal active components from interference and limiting the diffusion of sulfides to them. This significantly improves the water and sulfur resistance of the catalytic coating, further enhancing the removal efficiency.

[0016] Furthermore, using Nb-CeO2 / WO3 as a carrier for the precious metal active ingredients can broaden the reaction temperature window of the precious metal active ingredients and improve the ability of ceramic catalytic filter tubes to denitrate and remove total non-methane hydrocarbons at low temperatures.

[0017] Preferably, the precious metal catalytic slurry comprises the following raw materials in the following mass fractions: 4-8 wt% precious metal catalyst, 10-14 wt% surfactant, and the balance water.

[0018] Preferably, the surfactant comprises one or a combination of two of hexadecyltrimethylammonium bromide and polyethylene glycol.

[0019] By adopting the above technical solution, the surfactant in the precious metal catalytic slurry can protect the precious metal catalyst, maintain the catalytic activity of the precious metal during the sintering process, and form an adsorption layer on the surface of the precious metal catalyst, physically blocking the influence of sulfides on the active components of the precious metal, and also facilitating the uniform dispersion of the precious metal catalyst.

[0020] Furthermore, the addition of surfactants can optimize the fluidity of the precious metal catalytic slurry and improve the uniformity of its distribution on the ceramic filter tube surface, thereby further amplifying the effect of the precious metal catalyst and improving the removal efficiency of the catalytic coating for multiple pollutants.

[0021] Preferably, the raw materials for the Nb-CeO2 / WO3 support include cerium salt, tungsten salt and niobium salt in a mass ratio of 1:(0.4-0.6):(0.05-0.1).

[0022] More preferably, the cerium salt includes one or a combination of two of cerium ammonium nitrate and cerium acetylacetonate.

[0023] More preferably, the tungsten salt includes one or more combinations of ammonium metatungstate, ammonium paratungstate, and ethyl tungstate.

[0024] More preferably, the niobium salt includes one or more combinations of niobium oxalate, niobium acetate, and niobium acetylacetonate.

[0025] Preferably, the noble metal catalyst is prepared according to the following method:

[0026] Cerium salt and tungsten salt were dissolved separately in alcohol solvent. Then, the cerium salt solution was added dropwise to the tungsten salt solution. After stirring and mixing for 3-4 hours, the mixture was allowed to stand for 20-25 hours. After drying and calcination, CeO2 / WO3 support was obtained. Niobium salt was dispersed in water, the pH was adjusted to neutral, and CeO2 / WO3 support was added and stirred evenly. After aging at 70-75℃ for 2-3 hours, Nb-CeO2 / WO3 support was obtained after filtration, washing, drying and calcination.

[0027] The noble metal salt was dissolved in water, and an Nb-CeO2 / WO3 support was added. The temperature was raised to 80-90℃, and the reaction was carried out for 2-3 hours. After washing, drying and calcination, the noble metal catalyst was obtained.

[0028] More preferably, the alcohol solvent includes any one of aqueous ethanol solution, aqueous methanol solution, aqueous isopropanol solution, and aqueous ethylene glycol solution.

[0029] More preferably, the precious metal salt includes one or a combination of two of palladium nitrate and platinum nitrate.

[0030] By employing the above technical solution, a composite of cerium dioxide and tungsten trioxide is formed through calcination, and then niobium is doped into it to obtain an Nb-CeO2 / WO3 support. Finally, a noble metal catalyst is formed by impregnation in a noble metal salt solution. In the Nb-CeO2 / WO3 support, CeO2 / WO3 forms the main framework, protecting the supported noble metal active components and preventing activity degradation during the sintering process of the ceramic catalytic filter. Simultaneously, the incorporation of niobium creates numerous oxygen vacancies, enhancing the noble metal catalyst's adsorption capacity for nitrides and non-methane hydrocarbons, increasing the conversion rate of multiple pollutants, and thus improving the catalytic removal efficiency of the catalytic coating for multiple pollutants. Furthermore, it provides protection for the noble metal active components, preventing sulfides or water molecules from covering and eroding the active sites.

[0031] Preferably, the vanadium-based catalytic slurry comprises the following raw materials in mass fractions: 8-15 wt% vanadium-based catalyst, 10-12 wt% dispersant, and the balance water; the vanadium-based catalyst comprises titanium dioxide and vanadium-based active ingredients in a mass ratio of (90-92):(8-10).

[0032] Preferably, the vanadium-based active ingredient includes 93-94 wt% ammonium metavanadate and 6-7 wt% catalytic promoter; the catalytic promoter includes ammonium metatungstate and / or ammonium heptamolybdate.

[0033] Preferably, the silicon dioxide is anatase titanium dioxide; the particle size of the titanium dioxide is 30-150 nm.

[0034] Preferably, the dispersant comprises one or a combination of two of polyethylene glycol and silicon nitride.

[0035] By adopting the above technical solution, the catalytic coating also incorporates a vanadium-based catalytic slurry. The vanadium-based catalyst in the vanadium-based catalytic slurry uses titanium dioxide as a support material, with the addition of ammonium metavanadate. After pyrolysis, vanadium pentoxide is generated, providing redox activity to the catalytic coating. This catalyzes the reduction of nitrogen compounds and the oxidation of organic matter, achieving synergistic removal of multiple pollutants in conjunction with the noble metal catalytic slurry. The titanium dioxide support helps disperse the vanadium-based active components in the slurry, inhibits agglomeration, amplifies catalytic efficiency, and forms a physical barrier, improving the anti-interference ability of the vanadium-based catalyst. While providing excellent denitrification, it also exhibits good water and sulfur resistance.

[0036] Furthermore, the vanadium-based active ingredient also includes a catalytic aid. The introduction of the catalytic aid can help improve the oxidation capacity of the vanadium-based active ingredient and its adsorption capacity for nitrogen compounds, thereby improving overall stability, widening the active temperature window, and increasing denitrification efficiency.

[0037] The catalytic coating composed of vanadium-based catalytic slurry and noble metal catalytic slurry can exhibit good catalytic activity in different temperature ranges. It significantly improves the removal efficiency of multiple pollutants, including non-methane total hydrocarbons. Moreover, the composite coating can greatly enhance the chemical poisoning and corrosion resistance of sulfides, protect the active ingredients from being affected, and thus improve the removal rate and stability.

[0038] Preferably, the loading amount of the precious metal catalytic slurry on the ceramic filter tube substrate is 0.05 to 0.15 wt%; the loading amount of the vanadium-based catalytic slurry on the ceramic filter tube substrate is 10 to 20 wt%.

[0039] Preferably, the catalytic coating is formed by first coating a noble metal catalytic slurry onto the surface of a ceramic filter substrate and then coating it with a vanadium-based catalytic slurry;

[0040] Alternatively, the catalytic coating can be formed by first coating a vanadium-based catalytic slurry onto the surface of a ceramic filter substrate and then coating it with a precious metal catalytic slurry.

[0041] Alternatively, the catalytic coating can be formed by mixing a noble metal catalytic slurry with a vanadium-based catalytic slurry and then coating the ceramic filter substrate together.

[0042] More preferably, the coating rate of the noble metal catalyst slurry is 0.05 to 0.1 m / s, and the coating cycle is 0.5 to 1 cycle; the coating rate of the vanadium-based catalyst slurry is 0.05 to 0.1 m / s, and the coating cycle is 2 to 4 cycles.

[0043] More preferably, the coating rate of the co-coating is 0.05 to 0.1 m / s, and the coating cycle is 2 to 4 times.

[0044] By adopting the above technical solution, coating the ceramic catalytic filter tube with two different catalytic slurries can ensure the uniformity of the catalytic coating, effectively improve the dispersion and adhesion of the slurry, and ensure that the catalytic coating will not crack after sintering. Moreover, after sintering, the catalytically active components in the two catalytic slurries can synergistically improve the overall denitrification and dust removal efficiency, achieve integrated removal of multiple pollutants, and also have good water and sulfur resistance, ensuring the catalytic activity of the catalytic coating.

[0045] Furthermore, the two catalytic slurries of the present invention can be directly mixed and coated onto the surface of ceramic filter tubes, which can greatly save process steps. Moreover, since the noble metal active component of the present invention is supported on the Nb-CeO2 / WO3 support, the vanadium-based catalytic active component will not conflict with the noble metal active component during the direct mixing process, thereby reducing the catalytic efficiency. In addition, the active sites between the two active components will not interfere with each other, thereby improving the adsorption and removal efficiency of nitrides by the catalytic coating.

[0046] Furthermore, the noble metal support of this invention also incorporates niobium. The introduction of niobium can improve the stability of the noble metal catalyst, preventing the active sites from being submerged and side reactions from catalytically combining with vanadium-based catalysts. At the same time, it can synergistically block the oxidation pathway of sulfides with the titanium dioxide support in the vanadium-based catalyst, and can also form oxygen vacancies with the vanadium-based active components to generate active oxygen. This not only improves the water and sulfur resistance of the catalytic coating, but also promotes the catalytic breakage of recalcitrant organic matter, and significantly enhances the removal of non-methane total hydrocarbons.

[0047] Secondly, the present invention provides a method for preparing an integrated ceramic catalytic filter tube, comprising the following process steps:

[0048] S1. Disperse the noble metal catalyst in water, add a surfactant, and mix thoroughly to obtain a noble metal catalyst slurry;

[0049] S2. Disperse titanium dioxide in water, stir and disperse, raise the temperature to 50-100℃, add vanadium-based active ingredients, stir and dissolve to form vanadium-based catalyst, then add dispersant, mix evenly to obtain vanadium-based catalytic slurry;

[0050] S3. The precious metal catalytic slurry and vanadium-based catalytic slurry are coated on the surface of the dried ceramic filter tube substrate. After drying, a catalytic coating is formed. Finally, the substrate is calcined at 300-400℃ for 2-3 hours to obtain an integrated ceramic catalytic filter tube.

[0051] By adopting the above technical solution, the present invention coats the surface of the ceramic filter tube substrate with a noble metal catalytic slurry and a vanadium-based catalytic slurry, thereby creating active sites on the filter tube surface for the synergistic removal of denitrification and non-methane total hydrocarbons, increasing the contact area between the active components in the catalytic coating and multiple pollutants, and achieving efficient synergistic removal of multiple pollutants.

[0052] Furthermore, the ceramic catalytic filter tube synthesis method of the present invention is simple and has a short cycle, and can achieve the synergistic removal of multiple pollutants without adding additional treatment units.

[0053] The third approach is to provide an application of an integrated ceramic catalytic filter tube, which is used for the synergistic removal of dust and multiple pollutants from industrial flue gas.

[0054] Preferably, the temperature for synergistic removal of pollutants is 180–400°C.

[0055] More preferably, the temperature for synergistic removal of pollutants is 200–300°C.

[0056] By adopting the above technical solution, the integrated ceramic catalytic filter tube provided by the present invention has excellent performance in decomposing nitrogen compounds and non-methane total hydrocarbons in different temperature ranges, good water and sulfur resistance, and high conversion rate of multiple pollutants.

[0057] The beneficial effects of this invention are:

[0058] 1. The ceramic catalytic filter tube of the present invention includes a catalytic coating on its surface. The catalytic coating is composed of a precious metal catalytic slurry and a vanadium-based catalytic slurry. This allows them to compensate for each other's insufficient activity in different temperature ranges, thereby improving the overall multi-pollutant removal efficiency of the catalytic coating. It can also maintain a good conversion rate at low temperatures. Furthermore, using the ceramic filter tube as the base material is not only beneficial for the distribution of the catalytic slurry but also for the interception of particulate pollutants, thus achieving integrated denitrification and dust removal and efficient treatment of multiple pollutants in flue gas.

[0059] 2. In the catalytic coating of the present invention, the noble metal catalytic alkaline solution includes a noble metal catalyst, wherein the noble metal active component is supported on an Nb-CeO2 / WO3 support. This amplifies the catalytic activity, improves the removal efficiency, and achieves the removal of non-methane total hydrocarbons. Furthermore, it protects the noble metal active component, improves the water and sulfur resistance of the catalytic coating, and reduces the poisoning and corrosion of the active material by sulfides. The introduction of the support also helps prevent conflicts between the noble metal active component and the vanadium-based active component when the noble metal catalytic slurry is directly mixed and coated with the vanadium-based catalytic slurry, thereby avoiding a reduction in the catalytic activity of the coating. Attached Figure Description

[0060] Figure 1 For the NO removal rate test in Experiment 1 of this invention, the NO content of Examples 1, 6, 7, 10, Comparative Examples 3, 5, and 6 as a function of temperature was measured. x A diagram illustrating the conversion rate test results;

[0061] Figure 2 This is a schematic diagram showing the conversion results of phCH3 as a function of temperature in Examples 1, 6, 7, 10, Comparative Examples 3, 5, and 6 during the removal rate test of Experiment 1 of the present invention.

[0062] Figure 3 In the stability test of Experiment 2 of this invention, Example 1 and Comparative Example 5 showed NO levels within a 168-hour operating time. x A schematic diagram of the conversion rate test results;

[0063] Figure 4 This is a schematic diagram showing the conversion rate test results of phCH3 in Example 1 and Comparative Example 5 during a 168-hour running time in the stability test of Experiment 2 of the present invention.

[0064] Figure 5 SEM images of the integrated ceramic catalytic filter tubes obtained in Examples 1, 6, 7 and 10 of this invention;

[0065] in Figure 5 In the examples, A and A1 are Example 1, B, B1 is Example 6, C, C1 is Example 7, D, and D1 is Example 10. Detailed Implementation

[0066] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0067] Preparation Example

[0068] Preparation Example 1: A noble metal catalyst was prepared according to the following method:

[0069] Dissolve 10g of cerium ammonium nitrate in 100mL of 20% ethanol aqueous solution to obtain a cerium salt solution; dissolve 5g of ammonium metatungstate in 100mL of 20% ethanol aqueous solution to obtain a tungsten salt solution.

[0070] The obtained cerium salt solution was added dropwise to the tungsten salt solution, stirred and mixed for 4 hours, allowed to stand for 24 hours, dried at 110℃, and then calcined at 400℃ for 3 hours to obtain the CeO2 / WO3 support.

[0071] 0.8 g of niobium oxalate was dispersed in 100 mL of water, the pH was adjusted to neutral, the CeO2 / WO3 support obtained above was added, and after stirring evenly, it was aged at 75 °C for 2 h. Finally, after filtration, washing, drying, and calcination at 350 °C for 3 h, Nb-CeO2 / WO3 support was obtained.

[0072] 1.2 g of palladium nitrate was dissolved in 250 mL of water, and 10 g of the Nb-CeO2 / WO3 support obtained above was added. The temperature was raised to 85 °C and the reaction was carried out for 2 h. After washing and drying, the catalyst was calcined at 300 °C for 2 h to obtain the noble metal catalyst.

[0073] Preparation Example 2, a noble metal catalyst, differs from Preparation Example 1 only in that the amount of ammonium metatungstate added is 4g, the amount of niobium oxalate added is 0.5g, and the amount of palladium nitrate added is 1g.

[0074] Preparation Example 3, a noble metal catalyst, differs from Preparation Example 1 only in that the amount of ammonium metatungstate added is 6g, the amount of niobium oxalate added is 1g, and the amount of palladium nitrate added is 1.5g.

[0075] Preparation Example 4, a noble metal catalyst, differs from Preparation Example 1 only in that an equal amount of platinum nitrate is used instead of palladium nitrate.

[0076] Preparation Example 5: A noble metal catalyst was prepared according to the following method:

[0077] Dissolve 10g of cerium ammonium nitrate in 100mL of 20% ethanol aqueous solution to obtain a cerium salt solution; dissolve 5g of ammonium metatungstate in 100mL of 20% ethanol aqueous solution to obtain a tungsten salt solution.

[0078] The obtained cerium salt solution was added dropwise to the tungsten salt solution, stirred and mixed for 4 hours, allowed to stand for 24 hours, dried at 110℃, and then calcined at 400℃ for 3 hours to obtain the CeO2 / WO3 support.

[0079] 1.2 g of palladium nitrate was dissolved in 250 mL of water, and 10 g of the CeO2 / WO3 support obtained above was added. The temperature was raised to 85 °C and the reaction was carried out for 2 h. After washing and drying, the catalyst was calcined at 300 °C for 2 h to obtain the noble metal catalyst.

[0080] Preparation Example 6: A noble metal catalyst was prepared according to the following method:

[0081] 10g of cerium ammonium nitrate was dissolved in 100mL of 20% ethanol aqueous solution to obtain a cerium salt solution; after standing for 24h, it was dried at 110℃ and then calcined at 400℃ for 3h to obtain a CeO2 support; 0.8g of niobium oxalate was dispersed in 100mL of water, the pH was adjusted to neutral, the CeO2 support obtained above was added, stirred evenly, aged at 75℃ for 2h, and finally filtered, washed, dried, and calcined at 350℃ for 3h to obtain a Nb-CeO2 support;

[0082] 1.2 g of palladium nitrate was dissolved in 250 mL of water, and 10 g of the Nb-CeO2 support obtained above was added. The temperature was raised to 85 °C and the reaction was carried out for 2 h. After washing and drying, the catalyst was calcined at 300 °C for 2 h to obtain the noble metal catalyst.

[0083] Preparation Example 7: A noble metal catalyst was prepared according to the following method:

[0084] 10g of cerium ammonium nitrate was dissolved in 100mL of 20% ethanol aqueous solution to obtain a cerium salt solution; after standing for 24h, it was dried at 110℃ and then calcined at 400℃ for 3h to obtain CeO2 support;

[0085] 1.2 g of palladium nitrate was dissolved in 250 mL of water, and 10 g of the CeO2 support obtained above was added. The temperature was raised to 85 °C and the reaction was carried out for 2 h. After washing and drying, the catalyst was calcined at 300 °C for 2 h to obtain the noble metal catalyst.

[0086] Example

[0087] Example 1: An integrated ceramic catalytic filter tube was prepared according to the following process steps:

[0088] S1. Disperse 0.6g of the noble metal catalyst prepared in Preparation Example 1 in 8.2g of water, add 1.2g of hexadecyltrimethylammonium bromide, mix well to obtain a noble metal catalyst slurry;

[0089] S2. Disperse 1.08g of titanium dioxide in 7.8g of water, stir and disperse, raise the temperature to 70℃, add 0.12g of vanadium-based active ingredient, which includes 94% ammonium metavanadate and 6% ammonium metatungstate, stir and dissolve to form a vanadium-based catalyst, then add 1g of polyethylene glycol, mix evenly to obtain vanadium-based catalyst slurry;

[0090] S3. The ceramic filter tube substrate is dried, and then the surface is coated with the above-obtained noble metal catalytic slurry at a coating rate of 0.05 m / s and a coating cycle of 1 time. Then, the surface is coated with the above-obtained vanadium-based catalytic slurry at a coating rate of 0.05 m / s and a coating cycle of 4 times. After drying at 110°C for 2 hours, a catalytic coating is formed. Finally, the substrate is calcined at 350°C for 2 hours to obtain an integrated ceramic catalytic filter tube.

[0091] The loading of the precious metal catalyst slurry was 0.1%, and the loading of the vanadium-based catalyst slurry was 13.1%.

[0092] Examples 2 and 3 describe an integrated ceramic catalytic filter tube, differing from Example 1 only in the adjustment of the raw material ratios of the precious metal catalytic slurry and the vanadium-based catalytic slurry, as shown in Table 1.

[0093] Table 1. Catalytic slurry formulations for Examples 1 to 3

[0094]

[0095] The noble metal catalysts used in all examples were those prepared in Example 1; the vanadium-based active components in Example 2 included 93% ammonium metavanadate and 7% ammonium metatungstate; the vanadium-based active components in Example 3 included 94% ammonium metavanadate and 6% ammonium metatungstate.

[0096] Example 4: An integrated ceramic catalytic filter tube, which differs from Example 1 only in that an equal amount of the noble metal catalyst prepared in Preparation Example 2 is used to replace the noble metal catalyst prepared in Preparation Example 1.

[0097] Example 5: An integrated ceramic catalytic filter tube, which differs from Example 1 only in that an equal amount of the noble metal catalyst prepared in Preparation Example 3 is used to replace the noble metal catalyst prepared in Preparation Example 1.

[0098] Example 6: An integrated ceramic catalytic filter tube, which differs from Example 1 only in that an equal amount of the noble metal catalyst prepared in Preparation Example 4 is used to replace the noble metal catalyst prepared in Preparation Example 1.

[0099] Example 7: An integrated ceramic catalytic filter tube, which differs from Example 1 only in that an equal amount of ammonium heptamolybdate is used to replace ammonium metatungstate, and the vanadium-based active ingredients include 94% ammonium metavanadate and 6% ammonium heptamolybdate.

[0100] Example 8, an integrated ceramic catalytic filter tube, differs from Example 1 only in that step S1 is prepared according to the following method:

[0101] 0.2g of the noble metal catalyst prepared in Preparation Example 1 was dispersed in 8.6g of water, and 1.2g of hexadecyltrimethylammonium bromide was added. After mixing evenly, a noble metal catalyst slurry was obtained.

[0102] Example 9: An integrated ceramic catalytic filter tube, differing from Example 1 only in that step S1 is prepared according to the following method:

[0103] 1.0 g of the noble metal catalyst prepared in Preparation Example 1 was dispersed in 7.8 g of water, and 1.2 g of cetyltrimethylammonium bromide was added. After mixing evenly, a noble metal catalyst slurry was obtained.

[0104] Example 10: An integrated ceramic catalytic filter tube, differing from Example 1 only in that step S3 is prepared according to the following method:

[0105] The ceramic filter substrate was dried, and the noble metal catalytic slurry prepared in Example 1 was mixed with vanadium-based catalytic slurry and then coated onto the surface of the ceramic filter substrate at a coating rate of 0.05 m / s and a coating cycle of 4 times. After drying at 110°C for 2 hours, a catalytic coating was formed. Finally, the substrate was calcined at 350°C for 2 hours to obtain an integrated ceramic catalytic filter.

[0106] Comparative Example

[0107] Comparative Example 1 is an integrated ceramic catalytic filter tube, which differs from Example 1 only in that an equal amount of the noble metal catalyst prepared in Preparation Example 5 is used to replace the noble metal catalyst prepared in Preparation Example 1.

[0108] Comparative Example 2, an integrated ceramic catalytic filter tube, differs from Example 1 only in that an equal amount of the noble metal catalyst prepared in Preparation Example 6 is used to replace the noble metal catalyst prepared in Preparation Example 1.

[0109] Comparative Example 3 is an integrated ceramic catalytic filter tube, which differs from Example 1 only in that an equal amount of the noble metal catalyst prepared in Preparation Example 7 is used to replace the noble metal catalyst prepared in Preparation Example 1.

[0110] Comparative Example 4, an integrated ceramic catalytic filter tube, differs from Example 1 only in that no catalytic aid is added to the vanadium-based active ingredient in step S2, and the vanadium-based active ingredient includes 100% ammonium metavanadate.

[0111] Comparative Example 5, an integrated ceramic catalytic filter tube, differs from Example 1 only in that step S1 is prepared according to the following method:

[0112] 0.072 g palladium nitrate was dispersed in 8.2 g water, and 1.2 g cetyltrimethylammonium bromide was added. After mixing evenly, a noble metal catalytic slurry was obtained.

[0113] Comparative Example 6: An integrated ceramic catalytic filter tube was prepared according to the following process steps:

[0114] S1. Disperse 0.072g palladium nitrate in 8.2g water, add 1.2g cetyltrimethylammonium bromide, mix well to obtain a noble metal catalytic slurry;

[0115] S2. Disperse 1.08g of titanium dioxide in 7.8g of water, stir and disperse, raise the temperature to 70℃, add 0.12g of vanadium-based active ingredient, which includes 94% ammonium metavanadate and 6% ammonium metatungstate, stir and dissolve to form a vanadium-based catalyst, then add 1g of polyethylene glycol, mix evenly to obtain vanadium-based catalyst slurry;

[0116] S3. The ceramic filter substrate is dried, and the above-mentioned precious metal catalytic slurry is mixed with vanadium-based catalytic slurry and then coated onto the surface of the ceramic filter substrate at a coating rate of 0.05 m / s and a coating cycle of 4 times. After drying at 110°C for 2 hours, a catalytic coating is formed. Finally, the substrate is calcined at 350°C for 2 hours to obtain an integrated ceramic catalytic filter.

[0117] Comparative Example 7: An integrated ceramic catalytic filter tube was prepared according to the following process steps:

[0118] S1. Disperse 1.08g of titanium dioxide in 7.8g of water, stir and disperse, raise the temperature to 70℃, add 0.12g of vanadium-based active ingredient, which includes 94% ammonium metavanadate and 6% ammonium metatungstate, stir and dissolve to form a vanadium-based catalyst, then add 1g of polyethylene glycol, mix evenly to obtain vanadium-based catalyst slurry;

[0119] S2. The ceramic filter tube substrate is dried, and the above-mentioned vanadium-based catalytic slurry is coated onto the surface of the ceramic filter tube substrate at a coating rate of 0.05 m / s and a coating cycle of 4 times. After drying at 110°C for 2 hours, a catalytic coating is formed. Finally, the substrate is calcined at 350°C for 2 hours to obtain an integrated ceramic catalytic filter tube.

[0120] Performance testing

[0121] The concentrations of the reactant gases involved in the removal reaction were adjusted to 500 ppm NO, 500 ppm NH2, 20 ppm SO2, 75 ppm ph CH3, 10% H2O and 10% O2, while maintaining the total flow rate of the reactant gases at 50 mL / min and the gas hourly space velocity (GHSV) at 60000 mL / g·h.

[0122] 1. Removal rate test: The integrated ceramic catalytic filter tubes obtained in the examples and comparative examples were cut into test samples with a size of 2mm×2mm×2mm. A small amount of quartz wool was added to the fixed bed reactor, and the test samples were placed on the quartz wool.

[0123] First, the reactant gas is introduced directly into the Gasmate (mixed gas permeation test and analyzer) detection system without passing through the test sample to ensure that the concentration of the prepared reactant gas reaches the set value. Then, the reactant gas is introduced into a fixed bed reactor and passed through the test sample. The heating rate is set to 10℃ / min, and the gas is kept at 200℃, 220℃, 240℃, 260℃, 280℃ and 300℃ for 1 hour respectively. Then, the composition of the outlet tail gas at each temperature point is tested.

[0124] Finally, NO was calculated at different temperature points. x Conversion rate (%) of phCH3.

[0125] The results of the above experiments are shown in Tables 2 and 3.

[0126] 2. Stability test: Cut a 30cm length of the integrated ceramic catalytic filter tube obtained in the examples and comparative examples, add a small amount of quartz wool to the fixed bed reactor, and place the test sample on the quartz wool.

[0127] First, the reactant gas was introduced directly into the Gasmate (mixed gas permeation analyzer) detection system without passing through the test sample to ensure that the concentration of the prepared reactant gas reached the set value. Then, the reactant gas was introduced into a fixed-bed reactor, passing through the test sample. The heating rate was set to 10℃ / min, and after the temperature reached 240℃, it was stabilized for 168 hours. The composition of the outlet exhaust gas before and after the operation was tested. Finally, the NO content was calculated before and after the operation. x Conversion rate (%) of phCH3.

[0128] The results of the above experiments are shown in Table 4.

[0129] Table 2 Results of Removal Rate Test 1

[0130]

[0131] Table 3 Results of Removal Rate Test 2

[0132]

[0133] Table 4 Stability Test Results

[0134]

[0135] According to Table 1, Table 2 and Figure 1 , Figure 2 , Figure 3 , Figure 4Based on Examples 1, 10, 5, 6 and 7, it can be seen that coating the surface of the ceramic filter tube with only one layer of vanadium-based catalytic slurry results in poor removal of non-methane total hydrocarbons, decreased stability, and reduced overall removal efficiency of multiple pollutants.

[0136] The noble metal catalyst in the noble metal catalytic slurry of this invention has a high removal rate and good stability because it uses Nb-CeO2 / WO3 as a support. It has a high removal efficiency for non-methane total hydrocarbons. Compared with Comparative Example 5, where the noble metal active components are not supported on the Nb-CeO2 / WO3 support, it can have excellent removal efficiency in different temperature ranges.

[0137] The integrated ceramic catalytic filter tube provided by this invention can still achieve good removal effect when the precious metal catalytic slurry and vanadium-based catalytic slurry are directly mixed, and maintains high stability after long-term operation. However, when the precious metal active component is not supported on the Nb-CeO2 / WO3 support and is directly mixed with the vanadium-based catalytic slurry, the two active components in the mixed slurry will conflict, the precious metal active component will be inhibited, the stability will decrease, and the removal rate of non-methane total hydrocarbons will be significantly reduced.

[0138] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An integrated ceramic catalytic filter tube, characterized in that, It includes a ceramic filter substrate and a catalytic coating; the raw materials for the catalytic coating include precious metal catalytic slurry and vanadium-based catalytic slurry; The noble metal catalytic slurry includes a noble metal catalyst; the noble metal catalyst uses Nb-CeO2 / WO3 as a support and platinum and / or palladium as active components; the mass ratio of the active component to the support is (0.1~0.15):1; The precious metal catalytic slurry comprises the following raw materials by mass fraction: 4-8 wt% precious metal catalyst, 10-14 wt% surfactant, and the balance water; The raw materials for the Nb-CeO2 / WO3 support include cerium salt, tungsten salt and niobium salt in a mass ratio of 1:(0.4~0.6):(0.05~0.1); The noble metal catalyst was prepared according to the following method: Cerium salt and tungsten salt were dissolved separately in alcohol solvent. Then, the cerium salt solution was added dropwise to the tungsten salt solution. After stirring and mixing for 3-4 hours, the mixture was allowed to stand for 20-25 hours. After drying and calcination, CeO2 / WO3 support was obtained. Niobium salt was dispersed in water, the pH was adjusted to neutral, and CeO2 / WO3 support was added and stirred evenly. After aging at 70-75℃ for 2-3 hours, Nb-CeO2 / WO3 support was obtained after filtration, washing, drying and calcination. The noble metal salt was dissolved in water, and an Nb-CeO2 / WO3 support was added. The temperature was raised to 80-90℃, and the reaction was carried out for 2-3 hours. After washing, drying and calcination, the noble metal catalyst was obtained. The vanadium-based catalytic slurry comprises the following raw materials by mass fraction: 8-15 wt% vanadium-based catalyst, 10-12 wt% dispersant, and the balance water; the vanadium-based catalyst comprises titanium dioxide and vanadium-based active ingredients in a mass ratio of (90-92):(8-10).

2. The integrated ceramic catalytic filter tube according to claim 1, characterized in that, The vanadium-based active ingredient comprises 93-94 wt% ammonium metavanadate and 6-7 wt% catalytic promoter; the catalytic promoter comprises ammonium metatungstate and / or ammonium heptamolybdate.

3. The integrated ceramic catalytic filter tube according to claim 1, characterized in that, The loading amount of the precious metal catalytic slurry on the ceramic filter substrate is 0.05 to 0.15 wt%; the loading amount of the vanadium-based catalytic slurry on the ceramic filter substrate is 10 to 20 wt%.

4. The integrated ceramic catalytic filter tube according to claim 1, characterized in that, The catalytic coating is formed by first coating a noble metal catalytic slurry onto the surface of a ceramic filter substrate and then coating it with a vanadium-based catalytic slurry. Alternatively, the catalytic coating can be formed by first coating a vanadium-based catalytic slurry onto the surface of a ceramic filter substrate and then coating it with a precious metal catalytic slurry. Alternatively, the catalytic coating can be formed by mixing a noble metal catalytic slurry with a vanadium-based catalytic slurry and then coating the ceramic filter substrate together.

5. A method for preparing an integrated ceramic catalytic filter tube according to any one of claims 1 to 4, characterized in that, The process includes the following steps: S1. Disperse the noble metal catalyst in water, add a surfactant, and mix thoroughly to obtain a noble metal catalyst slurry; S2. Disperse titanium dioxide in water, stir and disperse, raise the temperature to 50-100℃, add vanadium-based active ingredients, stir and dissolve to form vanadium-based catalyst, then add dispersant, mix evenly to obtain vanadium-based catalytic slurry; S3. The precious metal catalytic slurry and vanadium-based catalytic slurry are coated on the surface of the dried ceramic filter tube substrate. After drying, a catalytic coating is formed. Finally, the substrate is calcined at 300-400℃ for 2-3 hours to obtain an integrated ceramic catalytic filter tube.

6. An application of an integrated ceramic catalytic filter tube according to any one of claims 1 to 4, characterized in that, The integrated ceramic catalytic filter tube is used for the synergistic removal of dust and multiple pollutants from industrial flue gas.

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