Disordered fiber environment catalytic material and preparation method and application thereof

Abstract

The application discloses a kind of disordered fiber environment catalytic materials and preparation method and application thereof, and the catalytic material takes titanium dioxide as carrier, tungsten cerium composite oxide is active component;With carrier mass as benchmark, the mass percentage content of active component is 5~20%.The catalytic material is environment-friendly, preparation process is simple, can efficiently catalyze oxidation chlorobenzene and catalytic reduction nitrogen oxide at low temperature, and has wide market application prospect.

Description

Technical Field

[0001] This invention relates to a disordered fiber environmental catalytic material, its preparation method, and its application, belonging to the field of air pollution control. Background Technology

[0002] The synergistic treatment of multiple pollutants in industrial flue gas has become a key technological challenge in the environmental protection field. With the continuous expansion of industrial capacity, the complex flue gas emitted from industries such as coal combustion, chemical processing, and waste incineration contains nitrogen oxides (NOx). x Pollutants such as NO and chlorinated aromatic hydrocarbons (e.g., chlorobenzene) exhibit significant coexistence characteristics. x Photochemical smog and acid rain are major contributors to nitrogen oxides (NOx). Chlorobenzene, a typical persistent organic pollutant, is highly carcinogenic, bioaccumulative, and chemically stable. It is difficult to degrade at low temperatures and readily forms highly toxic dioxins. Traditional stepwise treatment processes suffer from drawbacks such as equipment redundancy, high energy consumption, and a significant risk of secondary pollution. Therefore, developing a process that can simultaneously treat NOx is crucial. x Multifunctional materials that combine catalytic reduction and deep oxidation of chlorobenzene can not only significantly reduce pollution control costs, but are also an inevitable choice in response to the national strategy of "synergistic efficiency improvement in pollution reduction and carbon reduction".

[0003] Currently, regarding NO x Research on the synergistic removal of chlorobenzene is still in the exploratory stage. In terms of catalytic material design, the mainstream approaches focus on two main routes: one is to modify traditional vanadium-based denitration catalysts by loading transition metals (such as Cu, Mn, Ce) or noble metals (Pt, Pd) to endow them with the ability to oxidize chlorobenzene. However, the chlorine free radicals generated by chlorobenzene cracking attack the V-OH active sites, initiating vanadium species volatilization and TiO2 sulfation. The second approach is to develop composite metal oxides (such as perovskite and spinel), but these materials generally suffer from poor low-temperature activity, weak resistance to water and sulfur poisoning, and low mechanical strength. Summary of the Invention

[0004] The purpose of this invention is to address the current status and existing problems of existing simultaneous denitrification and dechlorination benzene catalysts, and to propose a disordered fiber environmental catalytic material, its preparation method, and its application.

[0005] A disordered fiber environmental catalytic material is characterized in that: the catalytic material uses titanium dioxide as a carrier and tungsten-cerium composite oxide as the active component, and is prepared by a combined method of turbulent assisted sol deposition-low temperature steam-strengthened fiber-step calcination to regulate the crystal phase; wherein, based on the mass of the carrier, the mass percentage of the active component is 5~20%.

[0006] A method for preparing the above-mentioned catalytic material, the method of which is as follows:

[0007] (1) Preparation of precursor networks by turbulent assisted sol deposition

[0008] Cerium salt, tungsten salt, citric acid, and deionized water were weighed and mixed to form a precursor solution. Titanium salt, acetylacetone, anhydrous ethanol, and isopropanol were weighed and mixed to form a chelation solution. Under constant temperature water bath stirring, the precursor solution was added dropwise to the chelation solution to form a mixed sol. The mixed sol was injected into three independent ultrasonic atomizers. Nitrogen gas flow controlled by three independent mass flow meters was used to carry the mixed sol droplets formed by the atomization of the sol in the three ultrasonic atomizers into three inlets of a four-necked round-bottom flask. The four-necked round-bottom flask was placed in a high-temperature oil bath. The fourth opening of the four-necked round-bottom flask was used as the gas outlet and sealed with a filter sponge. After the turbulent assisted sol deposition was completed, the powder on the inner wall of the round-bottom flask was scraped off to obtain the fiber precursor network.

[0009] (2) Preparation of fiber materials by low-temperature steam strengthening fiber

[0010] The fiber precursor network obtained in step (1) is first placed in a beaker and then placed in a hydrothermal reactor. Deionized water is added along the inner wall of the hydrothermal reactor. Finally, the hydrothermal reactor is placed in an oven for low-temperature steam strengthening. After the low-temperature steam strengthening is completed, the beaker is taken out and placed in an oven to dry to obtain the reinforced fiber material.

[0011] (3) Preparation of disordered fiber catalytic materials by step-calcination to regulate crystal phase

[0012] The reinforced fiber material obtained in step (2) is placed in a muffle furnace, heated to 200~250℃ and held for 2~3 hours, then heated to 350~450℃ and held for 2~4 hours, and finally heated to 500~600℃ and held for 1~2 hours to obtain disordered fiber catalytic material.

[0013] In the above method: the cerium salt mentioned in step (1) is cerium nitrate hexahydrate or cerium chloride, the tungsten salt is ammonium metatungstate, the titanium salt is tetrabutyl titanate, the molar ratio of tungsten to cerium in the tungsten-cerium composite oxide is 1~3:1~3, the mass ratio of cerium salt, citric acid and deionized water is 1:(2~4):(10~20), and the mass ratio of titanium salt, acetylacetone, anhydrous ethanol and isopropanol is 1:(0.5~1):(8~16):(3~6).

[0014] In the above method: the temperature of the continuous constant temperature water bath stirring in step (1) is 40~60℃, the speed of the continuous constant temperature water bath stirring is 50~100rpm, and the time of the continuous constant temperature water bath stirring is 6~12h.

[0015] In the above method: the mass ratio of the mixed sol injected into the three independent ultrasonic atomizers in step (1) is 1:(2~3):(4~6), the frequency of the ultrasonic atomizer atomizing the sol is 1.5~1.8MHz, and the droplet size of the ultrasonic atomizer atomizing the sol is 2~5μm.

[0016] In the above method: the gas flow rates of the nitrogen gas flow independently controlled by the three mass flow meters in step (1) are (100~200) mL / min, (200~600) mL / min and (400~1200) mL / min, respectively, and the temperature of the high-temperature oil bath is 260~280℃.

[0017] In the above method: the filter sponge mentioned in step (1) is a polyurethane filter sponge, which was purchased from Suzhou Jiahe Purification Technology Group Co., Ltd.

[0018] In the above method: the amount of deionized water added in step (2) is 8~16% of the volume of the hydrothermal reactor, the temperature of low-temperature steam enhancement is 110~120℃, the time of low-temperature steam enhancement is 10~20h, the drying temperature is 80~100℃, and the drying time is 6~12h.

[0019] The catalytic material prepared by the above method is used in the simultaneous denitration and dechlorination of benzene.

[0020] In the technical solution of this invention: the above-mentioned denitrification is selective catalytic reduction of nitrogen oxides, and the dechlorination of benzene is catalytic oxidation of chlorobenzene.

[0021] The experimental conditions for evaluating the catalyst activity of this invention were as follows: 0.5 g of 20-40 mesh catalyst was poured into a quartz tube with an inner diameter of 6 mm, fixed with quartz wool and wire mesh, and placed in a tube furnace. The actual temperature of the catalytic reaction was adjusted by controlling the heating temperature of the tube furnace. The inlet gas components were: NO (500 ppm), NH3 (500 ppm), O2 (10 vol.%), chlorobenzene (200 ppm), and the remainder being N2. The total gas flow rate was 500 mL / min, and the temperature was controlled between 160 and 300 °C, with a stabilization time of 30 min at every 20 °C. The NO concentration was measured using a flue gas analyzer, and the chlorobenzene concentration was measured using gas chromatography. Within the temperature range of 200-260 °C, the catalyst denitrification efficiency was consistently higher than 90%, and the chlorobenzene oxidation efficiency was consistently higher than 90%.

[0022] Beneficial effects:

[0023] (1) To avoid the problem of uniform fiber orientation and diameter distribution in conventional electrospinning or deposition methods, this invention uses turbulence-assisted sol deposition to prepare precursor networks. It mainly generates controllable turbulence in a limited space through three independently controlled nitrogen carrier gas flows with different flow rates. Nitrogen gas with different flow rates carries sol droplets and causes irregular collisions, aggregation and vortex motion in the reactor. When the droplets generated by ultrasonic atomization are deposited, pyrolyzed and nucleated on the hot substrate, they are disturbed by random momentum transfer and concentration fluctuations. This turbulent disturbance can effectively destroy the spatiotemporal symmetry of fiber growth and promote the non-steady-state condensation and precipitation of titanium, cerium and tungsten precursors, thereby spontaneously forming a three-dimensional disordered fiber network with alternating long and short, uneven thickness and mutual entanglement. Compared with fibers prepared by conventional electrospinning, disordered fibers can expose more lattice defects and edge active sites, forming more developed multi-level through-pores, thus providing ideal active sites for the diffusion and adsorption of reactant molecules and enhancing the low-temperature performance of catalytic materials.

[0024] (2) To avoid the problems of fiber sintering brittle fracture and pore collapse caused by traditional high-temperature calcination, this invention utilizes deionized water to generate saturated water vapor in a closed environment of a hydrothermal reactor. Then, the saturated water vapor provides a "gas-solid" reaction interface: the adsorption of water molecules on the fiber surface and the effect of capillary forces can promote slight local dissolution and surface hydroxylation of adjacent fibers at the contact point. Subsequently, during the drying process, strong chemical bonds of Ti-O-Ce, Ti-OW and WO-Ce are formed through hydrogen bonding and dehydration condensation, thereby enhancing the mechanical strength and structural stability of the fiber network. At the same time, the saturated water vapor can effectively promote the migration, hydrolysis and condensation of cerium nitrate and ammonium metatungstate precursors on the fiber surface and inside, achieving high dispersion and precrystallization of the cerium tungstate active component on the carrier. In addition, compared with the conventional hydrothermal reaction method, this invention physically isolates the fiber precursor network from deionized water through a beaker and reacts with it only through saturated water vapor, avoiding the transformation of the micro-fiber structure of the fiber precursor network in the liquid phase environment of the hydrothermal reaction.

[0025] (3) To avoid the problems of coarse grains, sudden drop in specific surface area, or phase separation caused by the difficulty in coordinating the kinetic contradiction between the crystallization of titanium dioxide support and the formation of the active phase of cerium tungstate in traditional single-stage rapid calcination, this invention adopts a three-stage heating program: The first stage (200~250℃) is mainly aimed at completely removing residual organic template agent and bound water in the precursor to achieve the initial "skeletonization" of the material; the second stage (350~450℃) is the window period for the controllable transformation of the amorphous phase of titanium dioxide to the highly active anatase phase. The relatively mild temperature avoids crystallization. The rapid growth of the particles is conducive to the formation of small-sized, highly crystalline TiO2 nanocrystals while maintaining the fibrous morphology. The third stage (500~600℃) drives the complete crystallization of cerium tungstate and the formation of a tight CeWO4 / TiO2 heterostructure interface with the titanium dioxide support, based on the already stable support structure. This synergistically optimizes the crystal structure, porosity and surface chemical properties of the material, so that the obtained catalytic material has both high specific surface area, abundant surface acidic sites and excellent redox ability, ultimately achieving efficient synergistic purification of nitrogen oxides and chlorobenzene systems.

[0026] Therefore, the catalytic material prepared by this invention is environmentally friendly, has a simple preparation process, low cost, and high cost-effectiveness. It also has advantages such as large specific surface area and sufficient exposure of active sites, enabling simultaneous denitrification and dechlorination of complex flue gas in non-electric industries, and has strong application and promotion value. Attached Figure Description

[0027] Figure 1 The image shows a scanning electron microscope (SEM) image of the catalyst prepared in Example 1.

[0028] Figure 2 The image shows a scanning electron microscope (SEM) image of the catalyst prepared in Example 1.

[0029] Figure 3 The image shows a scanning electron microscope (SEM) image of the catalyst prepared in Comparative Example 1.

[0030] Figure 4 The NO removal performance of the catalysts prepared in Examples 1-4 and Comparative Example 1 is shown in the graph.

[0031] Figure 5 The graph shows the chlorobenzene oxidation performance of the catalysts prepared in Examples 1-4 and Comparative Example 1. Detailed Implementation

[0032] The present invention will be further described below with reference to the embodiments. The embodiments are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0033] Example 1

[0034] (1) Preparation of precursor networks by turbulent assisted sol deposition

[0035] Weigh out 0.434g of cerium nitrate hexahydrate, 0.246g of ammonium metatungstate, 0.868g of citric acid, and 4.340g of deionized water and mix them to form a precursor solution. Then weigh out 34.427g of tetrabutyl titanate, 17.214g of acetylacetone, 275.416g of anhydrous ethanol, and 103.281g of isopropanol and mix them to form a chelation solution. Under constant temperature water bath stirring (50 rpm) at 40℃, the precursor solution is added dropwise to the chelation solution and stirred for 6 hours to form a mixed sol. The mixed sol is then injected into three independent ultrasonic atomizers (the masses of mixed sol injected into the three ultrasonic atomizers are 62.318g, 124.636g, and 249.272g, respectively). The frequency of the gel was 1.5MHz, and the droplet size of the sol atomized by the ultrasonic atomizer was 2μm. Then, the mixed sol droplets formed by the sol atomized by the three ultrasonic atomizers were introduced into the three inlets of a four-necked round-bottom flask using nitrogen gas flow rates controlled independently by three mass flow meters (gas flow rates of 100mL / min, 200mL / min and 400mL / min, respectively, with the nitrogen flow rate being proportional to the mass of the injected mixed sol). The four-necked round-bottom flask was placed in a 260℃ high-temperature oil bath. The fourth port of the four-necked round-bottom flask was used as the gas outlet and sealed with a polyurethane filter sponge (purchased from Suzhou Jiahe Purification Technology Group Co., Ltd.). After the turbulent assisted sol deposition was completed, the powder on the inner wall of the round-bottom flask was scraped off to obtain the fiber precursor network.

[0036] (2) Preparation of fiber materials by low-temperature steam strengthening fiber

[0037] The fiber precursor network obtained in step (1) was first placed in a 100mL beaker and then placed in a 200mL hydrothermal reactor. 16mL of deionized water was added along the inner wall of the hydrothermal reactor. Finally, the hydrothermal reactor was placed in an oven and steam-strengthened at 110℃ for 10h. After the steam-strengthening was completed, the beaker was removed and dried in an oven at 80℃ for 12h to obtain the reinforced fiber material.

[0038] (3) Preparation of disordered fiber catalytic materials by step-calcination to regulate crystal phase

[0039] The reinforced fiber material obtained in step (2) was placed in a muffle furnace, first heated to 200℃ and held for 3 hours, then heated to 450℃ and held for 2 hours, and finally heated to 500℃ and held for 2 hours to obtain disordered fiber catalytic material (based on the mass of the support, the mass percentage of the active component is 5%, and the scanning electron microscope image of the catalyst is shown in the figure). Figure 1 and Figure 2 (as shown)

[0040] (4) Catalytic activity test

[0041] Take 0.5g of 20-40 mesh catalyst and pour it into a quartz tube with an inner diameter of 6mm. Fix it with quartz wool and wire mesh. Place the quartz tube in a tube furnace and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tube furnace. Inlet gas components: NO (500ppm), NH3 (500ppm), O2 (10vol.%), chlorobenzene (200ppm), and the remainder is N2. The total gas flow rate is 500mL / min. The temperature is controlled between 160-300℃, and the temperature is maintained at 20℃ for 30min. The NO concentration is measured using a flue gas analyzer, and the chlorobenzene concentration is measured using gas chromatography. Within the temperature range of 200-260℃, the catalyst denitrification efficiency is higher than 90%, and the chlorobenzene oxidation efficiency is higher than 90%.

[0042] Example 2

[0043] (1) Preparation of precursor networks by turbulent assisted sol deposition

[0044] Weigh out 0.246g of cerium chloride, 0.246g of ammonium metatungstate, 0.984g of citric acid, and 4.920g of deionized water and mix them to form a precursor solution. Then weigh out 17.214g of tetrabutyl titanate, 17.214g of acetylacetone, 275.424g of anhydrous ethanol, and 103.284g of isopropanol and mix them to form a chelation solution. Under constant temperature water bath stirring (70rpm) at 50℃, the precursor solution is added dropwise to the chelation solution and stirred for 8 hours to form a mixed sol. The mixed sol is then injected into three independent ultrasonic atomizers (the masses of mixed sol injected into the three ultrasonic atomizers are 41.953g, 125.859g, and 251.718g, respectively, and the ultrasonic atomizers atomize the sol...). The ultrasonic atomizer atomized sol at a frequency of 1.7 MHz with a droplet size of 4 μm, and then nitrogen gas flow controlled independently by three mass flow meters (gas flow rates of 200 mL / min, 600 mL / min and 1200 mL / min, respectively, with the nitrogen flow rate proportional to the mass of the injected mixed sol) was used to carry the mixed sol droplets formed by the ultrasonic atomizer into three inlets of a four-necked round-bottom flask. The four-necked round-bottom flask was placed in a 270℃ high-temperature oil bath. The fourth port of the four-necked round-bottom flask was used as the gas outlet and sealed with polyurethane filter sponge (purchased from Suzhou Jiahe Purification Technology Group Co., Ltd.). After the turbulent assisted sol deposition was completed, the powder on the inner wall of the round-bottom flask was scraped off to obtain the fiber precursor network.

[0045] (2) Preparation of fiber materials by low-temperature steam strengthening fiber

[0046] The fiber precursor network obtained in step (1) was first placed in a 100mL beaker and then placed in a 200mL hydrothermal reactor. 20mL of deionized water was added along the inner wall of the hydrothermal reactor. Finally, the hydrothermal reactor was placed in an oven and steam-strengthened at 115℃ for 14h. After the steam-strengthening was completed, the beaker was removed and dried in an oven at 90℃ for 8h to obtain the reinforced fiber material.

[0047] (3) Preparation of disordered fiber catalytic materials by step-calcination to regulate crystal phase

[0048] The reinforced fiber material obtained in step (2) is placed in a muffle furnace, heated to 220°C and held for 2 hours, then heated to 400°C and held for 3 hours, and finally heated to 550°C and held for 1 hour to obtain disordered fiber catalytic material (based on the mass of the carrier, the mass percentage of the active component is 10%).

[0049] (4) Catalytic activity test

[0050] Take 0.5g of 20-40 mesh catalyst and pour it into a quartz tube with an inner diameter of 6mm. Fix it with quartz wool and wire mesh. Place the quartz tube in a tube furnace and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tube furnace. Inlet gas components: NO (500ppm), NH3 (500ppm), O2 (10vol.%), chlorobenzene (200ppm), and the remainder is N2. The total gas flow rate is 500mL / min. The temperature is controlled between 160-300℃, and the temperature is maintained at 20℃ for 30min. The NO concentration is measured using a flue gas analyzer, and the chlorobenzene concentration is measured using gas chromatography. Within the temperature range of 200-260℃, the catalyst denitrification efficiency is higher than 90%, and the chlorobenzene oxidation efficiency is higher than 90%.

[0051] Example 3

[0052] (1) Preparation of precursor networks by turbulent assisted sol deposition

[0053] Weigh out 0.434g of cerium nitrate hexahydrate, 0.246g of ammonium metatungstate, 1.302g of citric acid, and 6.510g of deionized water and mix them to form a precursor solution. Then weigh out 11.476g of tetrabutyl titanate, 9.181g of acetylacetone, 114.760g of anhydrous ethanol, and 57.380g of isopropanol and mix them to form a chelation solution. Under constant temperature water bath stirring (100rpm) at 60℃, the precursor solution is added dropwise to the chelation solution and stirred for 12h to form a mixed sol. The mixed sol is then injected into three independent ultrasonic atomizers (the masses of mixed sol injected into the three ultrasonic atomizers are 25.161g, 62.903g, and 113.225g, respectively). The frequency of the gel was 1.8MHz, and the droplet size of the sol atomized by the ultrasonic atomizer was 5μm. Then, the mixed sol droplets formed by the sol atomized by the three ultrasonic atomizers were introduced into the three inlets of a four-necked round-bottom flask using nitrogen gas flow rates controlled independently by three mass flow meters (gas flow rates of 120mL / min, 300mL / min and 540mL / min, respectively, with the nitrogen flow rate being proportional to the mass of the injected mixed sol). The four-necked round-bottom flask was placed in a high-temperature oil bath at 280℃. The fourth port of the four-necked round-bottom flask was used as the gas outlet and sealed with a polyurethane filter sponge (purchased from Suzhou Jiahe Purification Technology Group Co., Ltd.). After the turbulent assisted sol deposition was completed, the powder on the inner wall of the round-bottom flask was scraped off to obtain the fiber precursor network.

[0054] (2) Preparation of fiber materials by low-temperature steam strengthening fiber

[0055] The fiber precursor network obtained in step (1) was first placed in a 100mL beaker and then placed in a 200mL hydrothermal reactor. 32mL of deionized water was added along the inner wall of the hydrothermal reactor. Finally, the hydrothermal reactor was placed in an oven and steam-strengthened at 120℃ for 20h. After the steam-strengthening was completed, the beaker was removed and dried in an oven at 100℃ for 6h to obtain the reinforced fiber material.

[0056] (3) Preparation of disordered fiber catalytic materials by step-calcination to regulate crystal phase

[0057] The reinforced fiber material obtained in step (2) is placed in a muffle furnace, heated to 250°C and held for 2 hours, then heated to 350°C and held for 4 hours, and finally heated to 600°C and held for 1 hour to obtain disordered fiber catalytic material (based on the mass of the carrier, the mass percentage of the active component is 15%).

[0058] (4) Catalytic activity test

[0059] Take 0.5g of 20-40 mesh catalyst and pour it into a quartz tube with an inner diameter of 6mm. Fix it with quartz wool and wire mesh. Place the quartz tube in a tube furnace and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tube furnace. Inlet gas components: NO (500ppm), NH3 (500ppm), O2 (10vol.%), chlorobenzene (200ppm), and the remainder is N2. The total gas flow rate is 500mL / min. The temperature is controlled between 160-300℃, and the temperature is maintained at 20℃ for 30min. The NO concentration is measured using a flue gas analyzer, and the chlorobenzene concentration is measured using gas chromatography. Within the temperature range of 200-260℃, the catalyst denitrification efficiency is higher than 90%, and the chlorobenzene oxidation efficiency is higher than 90%.

[0060] Example 4

[0061] (1) Preparation of precursor networks by turbulent assisted sol deposition

[0062] Weigh out 0.246g of cerium chloride, 0.246g of ammonium metatungstate, 0.738g of citric acid, and 3.690g of deionized water to form a precursor solution. Then weigh out 8.607g of tetrabutyl titanate, 6.886g of acetylacetone, 103.284g of anhydrous ethanol, and 43.035g of isopropanol and mix them to form a chelation solution. Under constant temperature water bath stirring (100rpm) at 60℃, the precursor solution is added dropwise to the chelation solution and stirred for 12 hours to form a mixed sol. The mixed sol is then injected into three independent ultrasonic atomizers (the masses of mixed sol injected into the three ultrasonic atomizers are 18.524g, 55.572g, and 92.620g, respectively, and the ultrasonic atomizer atomization frequency of the sol is...). The ultrasonic atomizer atomized sol droplets with a frequency of 1.8 MHz and a droplet size of 5 μm were generated. Then, nitrogen gas flow was independently controlled by three mass flow meters (the gas flow rates were 150 mL / min, 450 mL / min and 750 mL / min, respectively, and the nitrogen flow rate was proportional to the mass of the injected mixed sol) to carry the mixed sol droplets formed by the ultrasonic atomizer into three inlets of a four-necked round-bottom flask. The four-necked round-bottom flask was placed in a 280℃ high-temperature oil bath. The fourth port of the four-necked round-bottom flask was used as the gas outlet and sealed with polyurethane filter sponge (purchased from Suzhou Jiahe Purification Technology Group Co., Ltd.). After the turbulent assisted sol deposition was completed, the powder on the inner wall of the round-bottom flask was scraped to obtain the fiber precursor network.

[0063] (2) Preparation of fiber materials by low-temperature steam strengthening fiber

[0064] The fiber precursor network obtained in step (1) was first placed in a 100mL beaker and then placed in a 200mL hydrothermal reactor. 32mL of deionized water was added along the inner wall of the hydrothermal reactor. Finally, the hydrothermal reactor was placed in an oven and steam-strengthened at 120℃ for 20h. After the steam-strengthening was completed, the beaker was removed and dried in an oven at 100℃ for 6h to obtain the reinforced fiber material.

[0065] (3) Preparation of disordered fiber catalytic materials by step-calcination to regulate crystal phase

[0066] The reinforced fiber material obtained in step (2) is placed in a muffle furnace, heated to 250°C and held for 2 hours, then heated to 350°C and held for 4 hours, and finally heated to 600°C and held for 1 hour to obtain disordered fiber catalytic material (based on the mass of the carrier, the mass percentage of the active component is 20%).

[0067] (4) Catalytic activity test

[0068] Take 0.5g of 20-40 mesh catalyst and pour it into a quartz tube with an inner diameter of 6mm. Fix it with quartz wool and wire mesh. Place the quartz tube in a tube furnace and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tube furnace. Inlet gas components: NO (500ppm), NH3 (500ppm), O2 (10vol.%), chlorobenzene (200ppm), and the remainder is N2. The total gas flow rate is 500mL / min. The temperature is controlled between 160-300℃, and the temperature is maintained at 20℃ for 30min. The NO concentration is measured using a flue gas analyzer, and the chlorobenzene concentration is measured using gas chromatography. Within the temperature range of 200-260℃, the catalyst denitrification efficiency is higher than 90%, and the chlorobenzene oxidation efficiency is higher than 90%.

[0069] Comparative Example 1

[0070] (1) Preparation of catalytic materials

[0071] Except that during the preparation of the catalyst material, the mixed sol was injected into three independent ultrasonic atomizers, each weighing 145.400g, and the flow rate of the nitrogen gas was controlled independently by three mass flow meters at 100mL / min, the other conditions were the same as in Example 1;

[0072] (2) Catalytic activity test

[0073] Take 0.5g of 20-40 mesh catalyst and pour it into a quartz tube with an inner diameter of 6mm. Fix it with quartz wool and wire mesh. Place the quartz tube in a tube furnace and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tube furnace. Inlet gas components: NO (500ppm), NH3 (500ppm), O2 (10vol.%), chlorobenzene (200ppm), and the remainder is N2. The total gas flow rate is 500mL / min. The temperature is controlled between 160-300℃, and the temperature is maintained at 20℃ for 30min. The NO concentration is measured using a flue gas analyzer, and the chlorobenzene concentration is measured using gas chromatography. Only at 260℃ are the catalyst denitrification efficiency and chlorobenzene conversion rate both higher than 90%.

[0074] (3) Comparison effect

[0075] Compared with Example 1, the injection mass of the mixed sol and the flow rate of the nitrogen gas in catalyst preparation step (1) are the same (the mass of the mixed sol in the ultrasonic atomizer needs to be proportional to the flow rate of the nitrogen gas, so the flow rate of the nitrogen gas also needs to be changed accordingly after the injection mass of the mixed sol changes). Although turbulence will also be formed due to different flask opening angles, the turbulence will cause regular collisions and aggregation in the reactor, which will not destroy the spatiotemporal symmetry of fiber growth, making it difficult to form disordered fibers, thereby making the fiber growth form an ordered structure, significantly reducing the number of lattice defects and edge active sites, and ultimately reducing the low-temperature catalytic activity.

Claims

1. A disordered fiber environmental catalytic material, characterized in that: The catalytic material uses titanium dioxide as a support and tungsten-cerium composite oxide as the active component. It is prepared by a combined method of turbulent assisted sol deposition, low-temperature steam-strengthened fiber, and step-calcination to regulate the crystal phase. The mass percentage of the active component is 5-20% based on the mass of the support.

2. A method for preparing the catalytic material according to claim 1, characterized in that: The preparation method of this catalytic material is as follows: (1) Preparation of precursor networks by turbulent assisted sol deposition A precursor solution was prepared by mixing cerium salt, tungsten salt, citric acid, and deionized water. A chelation solution was prepared by mixing titanium salt, acetylacetone, anhydrous ethanol, and isopropanol. The precursor solution was added dropwise to the chelation solution under constant temperature water bath stirring to form a mixed sol. The mixed sol was injected into three independent ultrasonic atomizers. Nitrogen gas flow controlled by three independent mass flow meters was used to carry the mixed sol droplets formed by the atomization of the sol by the three ultrasonic atomizers into three inlets of a four-necked round-bottom flask. The four-necked round-bottom flask was placed in a high-temperature oil bath. The fourth opening of the four-necked round-bottom flask was used as the gas outlet and sealed with a filter sponge. After the turbulent assisted sol deposition was completed, the powder on the inner wall of the round-bottom flask was scraped off to obtain the fiber precursor network. (2) Preparation of fiber materials by low-temperature steam strengthening fiber The fiber precursor network obtained in step (1) is first placed in a beaker and then placed in a hydrothermal reactor. Deionized water is added along the inner wall of the hydrothermal reactor. Finally, the hydrothermal reactor is placed in an oven for low-temperature steam strengthening. After the low-temperature steam strengthening is completed, the beaker is taken out and placed in an oven to dry to obtain the reinforced fiber material. (3) Preparation of disordered fiber catalytic materials by step-calcination to regulate crystal phase The reinforced fiber material obtained in step (2) is placed in a muffle furnace, heated to 200~250℃ and held for 2~3 hours, then heated to 350~450℃ and held for 2~4 hours, and finally heated to 500~600℃ and held for 1~2 hours to obtain disordered fiber catalytic material.

3. The preparation method according to claim 2, characterized in that: The cerium salt mentioned in step (1) is cerium nitrate hexahydrate or cerium chloride, the tungsten salt is ammonium metatungstate, and the titanium salt is tetrabutyl titanate; the molar ratio of tungsten to cerium in the tungsten-cerium composite oxide is 1~3:1~3, the mass ratio of cerium salt, citric acid and deionized water in the precursor solution is 1:(2~4):(10~20); the mass ratio of titanium salt, acetylacetone, anhydrous ethanol and isopropanol in the chelation solution is 1:(0.5~1):(8~16):(3~6).

4. The preparation method according to claim 2, characterized in that: The temperature of the continuous constant temperature water bath stirring in step (1) is 40~60℃, the speed of the continuous constant temperature water bath stirring is 50~100rpm, and the time of continuous constant temperature water bath stirring is 6~12h.

5. The preparation method according to claim 2, characterized in that: The mass ratio of the mixed sol injected into the three independent ultrasonic atomizers in step (1) is 1:(2~3):(4~6), the frequency of the ultrasonic atomizer atomizing the sol is 1.5~1.8MHz, and the droplet size of the ultrasonic atomizer atomizing the sol is 2~5μm.

6. The preparation method according to claim 2, characterized in that: The gas flow rates of the nitrogen gas flow independently controlled by the three mass flow meters in step (1) are (100~200) mL / min, (200~600) mL / min and (400~1200) mL / min, respectively, and the temperature of the high-temperature oil bath is 260~280℃.

7. The preparation method according to claim 2, characterized in that: The filter sponge mentioned in step (1) is a polyurethane filter sponge.

8. The preparation method according to claim 2, characterized in that: The amount of deionized water added in step (2) is 8-16% of the volume of the hydrothermal reactor, the temperature of low-temperature steam enhancement is 110-120℃, the time of low-temperature steam enhancement is 10-20h, the drying temperature is 80-100℃, and the drying time is 6-12h.

9. The application of the catalyst according to claim 1 in the simultaneous denitration and dechlorination of benzene.

10. The application according to claim 9, characterized in that, The denitrification process involves selective catalytic reduction of nitrogen oxides, and the dechlorination process involves catalytic oxidation of chlorobenzene.

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