Preparation method and application of dust and nitrogen integrated catalytic filter bag

Abstract

The application discloses a preparation method and application of dust and nitrogen oxide integrated catalytic filter bags and belongs to the field of industrial flue gas dust and nitrogen oxide collaborative treatment. The dust and nitrogen oxide integrated catalytic filter bag provided by the application is first subjected to modulation of vanadium-tungsten-titanium or vanadium-molybdenum-titanium catalytic slurry (solid content is 15-20 wt%) with different TiO2 particle sizes, then a programmable double-module membrane electrode spraying machine is used to spray the vanadium-based catalytic slurry on the wall surface of the catalytic filter bag, and finally the loading amount of the vanadium-based catalyst is 120-140 g / m 2 . The dust and nitrogen oxide integrated catalytic filter bag synthesis method is simple, the programmable double-module membrane electrode spraying machine can be used to realize large-area, uniform and controllable catalyst coating, and the production efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of synergistic treatment of industrial flue gas dust and nitrogen oxides, specifically relating to a method for preparing and applying an integrated dust and nitrogen oxide catalytic filter bag. Background Technology

[0002] With increasingly stringent global environmental standards, fine particulate matter (PM2.5) in industrial flue gas is becoming more prevalent. 2.5 / PM 10 ) and nitrogen oxides (NO) x The coordinated and efficient governance of dust and nitrogen oxides has become a key challenge. Although the traditional series process of "dust removal followed by denitrification" (such as bag filter + SCR) can meet the standards, it has inherent problems such as long process, high equipment investment and operating costs, easy deactivation and blockage of catalysts, and potential ammonia escape. Therefore, there is an urgent need to develop compact and efficient technologies that can achieve "dust removal and denitrification integration" in one unit to simplify the process, reduce costs and improve overall environmental efficiency.

[0003] Catalytic filter technology loads a denitrification catalyst (such as a TiO2-based catalyst) onto the surface of traditional filter bag fibers, enabling it to catalytically reduce or decompose NO using waste heat from flue gas while filtering and capturing particulate matter. x This achieves the goal of "single-bag synergistic removal" of particulate matter and nitrogen oxides. The principle is as follows: when dust-laden flue gas passes through the filter bag, particulate matter is intercepted and captured; simultaneously, the waste heat of the flue gas activates the surface catalyst, removing NO... x Selective catalytic reduction to N2. This technology effectively integrates two functions, significantly reducing equipment footprint and energy consumption, and has become a cutting-edge direction in the deep treatment of industrial flue gas.

[0004] However, the bottleneck for the large-scale application of this technology lies in the catalyst loading process. Currently, the mainstream industrial method is "impregnation" or "wash-coating": the entire filter bag or its base fabric is immersed in the catalyst slurry tank. This method has obvious drawbacks: (1) Low catalyst utilization efficiency and serious waste: a large amount of catalyst is deeply immersed in the fiber and cannot be exposed to the flue gas contact surface, resulting in more than 70% of precious metals or active components being ineffectively loaded; (2) Poor coating uniformity and controllability: it is easy to form local areas that are too thick or too thin, and it is difficult to accurately control the loading of specific areas of the filter bag (such as the dust-facing surface), affecting the uniformity of catalytic activity and the final denitrification efficiency; (3) Damage to physical structure and catalytic performance: drying and sintering after impregnation can easily cause the active components of the catalyst to agglomerate and migrate. At the same time, excessive slurry penetration may cause the filter bag pores to be blocked, increasing airflow resistance and reducing the overall filtration performance; (4) Large raw material loss, complicated process and poor environmental protection: the impregnation tank needs to be frequently replaced and a large amount of waste slurry needs to be treated, resulting in high maintenance costs. Therefore, there is an urgent need to invent a new catalyst loading technology to achieve uniform coating control while improving production efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing and applying an integrated dust and nitrogen oxide catalytic filter bag. The catalytic filter bag provided by this invention has a simple preparation method and excellent performance, achieving highly efficient catalytic removal of nitrogen oxides at 200-260 °C. Furthermore, the catalyst exhibits good water and sulfur resistance.

[0006] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is as follows: In a first aspect, embodiments of the present invention provide an integrated dust and nitrogen oxide catalytic filter bag, comprising catalytic slurry preparation and spraying; The vanadium-based catalyst slurry has a solid content of 15-20 wt%. The vanadium-based catalytic slurry is loaded at a rate of 120-140 g / m³ onto the catalytic filter bag. 2 .

[0007] Furthermore, the blank filter bag is woven from glass fibers with a diameter of 5~25 µm; Secondly, embodiments of the present invention provide a method for preparing the vanadium-based catalytic slurry described in the first aspect, comprising the following steps: Weigh out a TiO2 dispersion with a solid content of 10%, heat the TiO2 dispersion to 50-80 ℃, then add ammonium metavanadate, ammonium metatungstate or ammonium heptamolybdate. After it is completely dissolved, add cellulose or PTFE binder to finally obtain a catalytic slurry with a vanadium-based catalyst solid content of 15-20 wt%.

[0008] Furthermore, the TiO2 dispersion has a particle size of 30 nm, 150 nm, or 300 nm, and its crystal phase is anatase.

[0009] Thirdly, embodiments of the present invention provide a method for preparing the integrated dust and nitrogen oxide catalytic filter bag described in the first aspect, comprising the following steps: (1) After drying the catalytic filter bag with a dryer, lay it flat on a large-area vacuum heating adsorption table. Select ultrasonic atomization spraying or pneumatic atomization spraying according to the characteristics of the catalyst slurry (such as viscosity and particle size). The programmable spraying path is preset by the software, and the movement trajectory of the nozzle is precisely controlled by the XYZ three-axis motion system to cover a maximum spraying area of ​​400×400 mm. Spray the catalytic filter bag evenly for two rounds.

[0010] (2) The obtained catalytic filter bag is dried at 100-120 ℃ for 2-4 h, and then calcined at 200-300 ℃ for 2-4 h to obtain the dust-nitrification integrated catalytic filter bag.

[0011] Furthermore, the spraying described in step (1) is characterized in that ultrasonic atomization spraying or pneumatic atomization spraying is selected according to the properties of the slurry, and the spraying path can be controlled by programming.

[0012] Fourthly, embodiments of the present invention provide a method for testing the denitrification performance of the aforementioned integrated dust and denitrification catalytic filter bag, comprising the following steps: The test is conducted in a self-made multifunctional filter bag evaluation device for dust removal and denitrification catalytic fibers; the catalytic filter bag is cut into circular pieces with a diameter of 150 mm and added to the reactor; 500 ppm NH3 and 500 ppm NO are introduced. x The denitrification performance was tested at 180-260 ℃ with 10% O2, 5% H2O, 30ppm SO2, and N2 as the balance gas, and the wind speed was maintained at 0.5 m / min.

[0013] Fifthly, embodiments of the present invention provide a method for testing the water and sulfur resistance performance of the above-mentioned integrated dust and nitrogen removal catalytic filter bag, comprising the following steps: The test is conducted in a self-made multifunctional filter bag evaluation device for dust removal and nitrogen removal catalytic fibers; the catalytic filter bag is cut into circular pieces with a diameter of 150 mm and added to a reactor; 500 ppm NH3 and 500 ppm NO are introduced. x 10% O2 and N2 were used as the equilibrium gas, the wind speed was maintained at 0.5 m / min, and the test was carried out at 260 ℃. After the reaction stabilized, 5% H2O and 30 ppm SO2 were introduced and maintained for 8 h. Then H2O and SO2 were cut off, and the denitrification efficiency was tested.

[0014] The technical solutions provided in the embodiments of the present invention have the following advantages or beneficial results: The dust and nitrogen oxide integrated catalytic filter bag provided by the present invention achieves efficient combination of vanadium-based catalytic slurry and catalytic filter bag by modulating vanadium-based catalytic slurry with different TiO2 particle sizes, realizing low-temperature and efficient removal of nitrogen oxides, while having good water and sulfur resistance.

[0015] The dust and nitrogen integrated catalytic filter bag provided by this invention uses a programmable dual-module membrane electrode spraying machine to spray catalytic slurry, which achieves precise control over the position, thickness, and area of ​​the catalytic slurry coating, and the process is highly automated, thus improving production efficiency.

[0016] The dust and nitrogen oxide integrated catalytic filter bag provided by this invention has a simple synthesis method, short cycle, and requires readily available and inexpensive raw materials. It achieves integrated dust and nitrogen oxide removal without adding an additional treatment unit and has broad application prospects. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0018] Figure 1 The denitrification reaction activity of catalysts A, B, C, D, E, F, G, and H prepared in Examples 1-6 and Comparative Example 1 as a function of temperature is shown. Figure 2 These are the water and sulfur resistance test results of catalysts A and G prepared in Example 1 and Comparative Example 1 of this invention, respectively; Figure 3 The dust and nitrogen oxide integrated catalytic filter bags prepared in Examples 1-6 and Comparative Example 1 of this invention are represented by catalyst A, catalyst B, catalyst C, catalyst D, catalyst E, catalyst F, catalyst G, and catalyst H, respectively, corresponding to the corresponding examples and comparative examples. Figure 4 This is the preparation process of the dust and nitrogen oxide integrated catalytic filter bag described in this invention. Detailed Implementation

[0019] The embodiments of the present invention are described in detail below, and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0020] Example 1 80 g of TiO2 dispersion with a solid content of 10% and a particle size of 30 nm was weighed. The TiO2 dispersion was heated to 80 °C, and then 5 g of ammonium metavanadate and 4 g of ammonium heptamolybdate were added and stirred for 30 min. After complete dissolution, 2.5 g of PTFE binder was added, finally obtaining a catalytic slurry with a vanadium-based catalyst solid content of 19.6 wt%. After drying the catalytic filter bag with a dryer, it was laid flat on a large-area vacuum heating adsorption stage, and ultrasonic atomization spraying was selected. The programmable spraying path was preset in the software, and the catalytic filter bag was uniformly sprayed for two rounds. The resulting catalytic filter bag was dried at 105 °C for 2 h, and then calcined at 280 °C for 2 h to obtain a catalyst loading of 136 g / m³. 2 The dust and nitrogen integrated catalytic filter bag is denoted as catalyst A.

[0021] Example 2 80 g of TiO2 dispersion with a solid content of 10% and a particle size of 150 nm was weighed. The TiO2 dispersion was heated to 70 °C, and then 5 g of ammonium metavanadate and 4 g of ammonium heptamolybdate were added and stirred for 30 min. After complete dissolution, 2.5 g of PTFE binder was added, finally obtaining a catalytic slurry with a vanadium-based catalyst solid content of 19.1 wt%. The catalytic filter bag was dried in a dryer and then laid flat on a large-area vacuum heating adsorption stage. Ultrasonic atomization spraying was selected, and the catalytic filter bag was uniformly sprayed for two rounds using a programmable spraying path preset by software. The resulting catalytic filter bag was dried at 120 °C for 2 h, and then calcined at 280 °C for 3 h to obtain a catalyst loading of 132 g / m³. 2 The dust and nitrogen integrated catalytic filter bag is designated as catalyst B.

[0022] Example 3 80 g of TiO2 dispersion with a solid content of 10% and a particle size of 300 nm was weighed. The TiO2 dispersion was heated to 60 °C, and then 5 g of ammonium metavanadate and 4 g of ammonium heptamolybdate were added and stirred for 30 min. After complete dissolution, 2.5 g of PTFE binder was added, finally obtaining a catalytic slurry with a vanadium-based catalyst solid content of 18.8 wt%. After drying the catalytic filter bag with a dryer, it was laid flat on a large-area vacuum heating adsorption stage, and pneumatic atomization spraying was selected. The programmable spraying path was preset in the software, and the catalytic filter bag was uniformly sprayed for two rounds. The resulting catalytic filter bag was dried at 110 °C for 2 h, and then calcined at 260 °C for 3 h to obtain a catalyst loading of 130 g / m³. 2 The dust and nitrogen integrated catalytic filter bag is denoted as catalyst C.

[0023] Example 4 80 g of TiO2 dispersion with a solid content of 10% and a particle size of 30 nm was weighed. The TiO2 dispersion was heated to 70 °C, and then 5 g of ammonium metavanadate and 4 g of ammonium metatungstate were added and stirred for 30 min. After complete dissolution, 2.5 g of cellulose binder was added, finally obtaining a catalytic slurry with a vanadium-based catalyst solid content of 17.7 wt%. After drying the catalytic filter bag with a dryer, it was laid flat on a large-area vacuum heating adsorption stage, and ultrasonic atomization spraying was selected. The programmable spraying path was preset in the software, and the catalytic filter bag was uniformly sprayed for two rounds. The resulting catalytic filter bag was dried at 110 °C for 2 h, and then calcined at 280 °C for 2 h to obtain a catalyst loading of 125 g / m³. 2 The dust and nitrogen integrated catalytic filter bag is denoted as catalyst D.

[0024] Example 5 80 g of TiO2 dispersion with a solid content of 10% and a particle size of 150 nm was weighed. The TiO2 dispersion was heated to 80 °C, and then 5 g of ammonium metavanadate and 4 g of ammonium metatungstate were added and stirred for 30 min. After complete dissolution, 2.5 g of cellulose binder was added, finally obtaining a catalytic slurry with a vanadium-based catalyst solid content of 18.1 wt%. The catalytic filter bag was dried in a dryer and then laid flat on a large-area vacuum heating adsorption stage. Ultrasonic atomization spraying was selected, and the catalytic filter bag was uniformly sprayed for two rounds using a programmable spraying path preset by software. The resulting catalytic filter bag was dried at 120 °C for 3 h, and then calcined at 280 °C for 3 h to obtain a catalyst loading of 129 g / m³. 2 The dust and nitrogen integrated catalytic filter bag is denoted as catalyst E.

[0025] Example 6 80 g of TiO2 dispersion with a solid content of 10% and a particle size of 300 nm was weighed. The TiO2 dispersion was heated to 60 °C, and then 5 g of ammonium metavanadate and 4 g of ammonium metatungstate were added and stirred for 30 min. After complete dissolution, 2.5 g of cellulose binder was added, finally obtaining a catalytic slurry with a vanadium-based catalyst solid content of 17.4 wt%. After drying the catalytic filter bag with a dryer, it was laid flat on a large-area vacuum heating adsorption stage, and pneumatic atomization spraying was selected. The programmable spraying path was preset in the software, and the catalytic filter bag was uniformly sprayed for two rounds. The resulting catalytic filter bag was dried at 105 °C for 3 h, and then calcined at 260 °C for 2 h to obtain a catalyst loading of 133 g / m³. 2 The integrated dust and nitrogen catalytic filter bag is denoted as catalyst F.

[0026] Comparative Example 1 Unlike Examples 1-6, 80 g of TiO2 dispersion with a solid content of 10% and a particle size of 300 nm was weighed. The TiO2 dispersion was heated to 80 °C, and then 5 g of ammonium metavanadate, 4 g of ammonium heptamolybdate, or ammonium metatungstate were added and stirred for 30 min. After complete dissolution, 2.5 g of PTFE binder was added, finally yielding catalytic slurries with solid contents of 18.5 wt% and 18.2 wt% for vanadium-based catalysts, respectively. After drying the catalytic filter bags with a dryer, they were immersed in the above vanadium-molybdenum-titanium or vanadium-tungsten-titanium catalytic slurries for 10 min, respectively. The filter bags were then removed and dried at 110 °C for 2 h, followed by calcination at 260 °C for 2 h to obtain catalyst loadings of 122 g / m³. 2 and 126 g / m 2 The dust and nitrogen integrated catalytic filter bags are denoted as catalysts G and H, respectively.

[0027] Application Example 1 Testing the denitrification activity of catalysts A, B, C, D, E, F, G, and H. The catalytic filter bag was cut into 150 mm diameter discs and tested using a self-made multifunctional filter bag evaluation device for dust removal and denitrification catalytic fibers. The concentrations of the reactant gas components were adjusted to 500 ppm NO, 500 ppm NH3, 30 ppm SO2, 5% H2O, and 10% O2, maintaining a wind speed of 0.5 m / min. Testing was conducted using Gasmate. Before testing, the reactant gas was switched to bypass the sample tube and enter the detection system directly to ensure the configured gas concentrations met the set values. The reactant gas was then switched back to allow it to pass through the catalyst under test. Finally, a temperature control program was set with a heating rate of 10 °C / min. −1 The temperature was maintained at each temperature point for 1 hour, and the composition of the exhaust gas at the outlet was detected in real time using infrared technology.

[0028] Water and sulfur resistance tests of catalyst A and catalyst G Catalysts A and G were dried and calcined, then cut into 150 mm diameter discs and tested using a self-made multifunctional filter bag evaluation device for dust removal and denitrification catalytic fibers. The concentrations of the reactant gas components were adjusted to 500 ppm NO, 500 ppm NH3, and 10% O2, maintaining a wind speed of 0.5 m / min. Testing was conducted using Gasmate. Before testing, the reactant gas was switched to bypass the sample tube and enter the detection system directly to ensure the configured gas concentrations met the set values. The reactant gas was then switched back to allow it to pass through the catalyst under test. Finally, a heating control program was set with a heating rate of 10 °C / min. −1The composition of the exhaust gas was detected in real time using infrared spectroscopy. The test was conducted at 260 °C. After the reaction stabilized, 5% H2O and 30ppm SO2 were introduced and maintained for 8 h. Then, H2O and SO2 were cut off, and the denitrification efficiency was tested.

[0029] Figure 1 The denitrification reaction activities of catalysts A, B, C, D, E, F, G, and H prepared in Examples 1-6 and Comparative Example 1 of this invention are shown as a function of temperature. It can be seen that the catalytic filter bags obtained by spraying using a programmable dual-module membrane electrode spraying machine have better performance than those obtained by the impregnation method. Furthermore, the catalytic filter bags obtained by spraying with vanadium-molybdenum-titanium slurry have significantly better performance than those obtained by spraying with vanadium-tungsten-titanium slurry. Among the prepared integrated dust and denitrification catalytic filter bags, catalyst A exhibits the best performance.

[0030] Figure 2 The figure shows the water and sulfur resistance test results of catalyst A prepared in Example 1 and catalyst G prepared in Comparative Example 1. After the denitrification activity stabilized at 260℃, 5% H2O and 30ppm SO2 were introduced. It can be seen that the activity of catalyst A decreased from 99% to 94%, and the activity of catalyst G decreased from 88% to 75%. Both catalysts maintained stable denitrification efficiency for the next 480 minutes. After the water and sulfur supply was stopped, the denitrification conversion rate returned to the previous level, indicating that both catalyst A and catalyst G have good water and sulfur resistance, and catalyst A has better performance.

[0031] Figure 3 Images of catalysts A, B, C, D, E, F, G, and H prepared in Examples 1-6 and Comparative Example 1 of this invention are shown. The results indicate that the coatings of catalysts A, B, C, D, E, and F are significantly more uniform than those of catalysts G and H.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dust- and nitrogen-refining integrated catalytic filter bag, characterized in that, This includes preparing the catalyst slurry and spraying the catalyst slurry onto blank filter bags; The steps for preparing the catalytic slurry include: Weigh out a TiO2 dispersion with a solid content of 10%, heat the TiO2 dispersion to 50-80 ℃, then add ammonium metavanadate, ammonium metatungstate or ammonium heptamolybdate, and after it is completely dissolved, add cellulose or PTFE binder to finally obtain a catalytic slurry with a vanadium-based catalyst solid content of 15-20 wt%. The requirement for spraying catalytic slurry onto blank filter bags is that the loading of the catalytic slurry onto the filter bag is 120-140 g / m³. 2 .

2. The integrated dust and nitrogen catalytic filter bag according to claim 1, characterized in that, Blank filter bags are woven from glass fibers with a diameter of 5 to 25 µm.

3. The integrated dust and nitrogen catalytic filter bag according to claim 1, characterized in that, The TiO2 dispersion contains TiO2 particles with a diameter of 30 nm, 150 nm, or 300 nm, and the TiO2 crystal phase is anatase.

4. The method for preparing the integrated dust and nitrogen oxide catalytic filter bag according to any one of claims 1-3, characterized in that, Catalytic slurry spraying was performed using a programmable dual-module membrane electrode spraying machine. (1) After drying the blank filter bag with a dryer, lay it flat on a large-area vacuum heating adsorption table. Select ultrasonic atomization spraying or pneumatic atomization spraying according to the characteristics of the catalytic slurry. The programmable spraying path is preset by the software, and the movement trajectory of the nozzle is precisely controlled by the XYZ three-axis motion system to cover a maximum spraying area of ​​400×400 mm. Spray the catalytic filter bag evenly for two rounds. (2) The obtained catalytic filter bag is dried at 100-120 ℃ for 2-4 h, and then calcined at 200-300 ℃ for 2-4 h to obtain the dust-nitrification integrated catalytic filter bag.

5. A method for testing the denitrification performance of catalytic filter bags, characterized in that, The catalytic filter bag described in claims 1-4 is used, comprising the following steps: The evaluation was conducted using a self-made multifunctional filter bag for dust removal and denitrification catalytic fiber. The catalytic filter bag was cut into 150 mm diameter discs and added to the reactor. 500 ppm NH3 and 500 ppm NO were then introduced. x The denitrification performance was tested at 180-260 ℃ with 10% O2, 5% H2O, 30ppm SO2, and N2 as the balance gas, and the wind speed was maintained at 0.5 m / min.

6. A method for testing the water and sulfur resistance of catalytic filter bags, characterized in that, The catalytic filter bag described in claims 1-4 is used, comprising the following steps: The evaluation was conducted using a self-made multifunctional filter bag evaluation device for dust removal and denitrification catalytic fiber. The catalytic filter bag was cut into circular pieces with a diameter of 150 mm and added to the reactor. 500 ppm NH3 and 500 ppm NO were then introduced. x 10% O2 and N2 were used as the equilibrium gas, the wind speed was maintained at 0.5 m / min, and the test was carried out at 260 ℃. After the reaction stabilized, 5% H2O and 30ppm SO2 were introduced and maintained for 8 h. Then H2O and SO2 were cut off, and the denitrification efficiency was tested.

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