A catalyst for chlorinated organic waste gas and its preparation method and application

Abstract

The present invention provides a catalyst for chlorinated organic waste gas, a preparation method thereof and an application thereof. The preparation method includes step S1: cleaning and filtering iron-containing dust to obtain iron sand; step S2: obtaining a crushed material, wherein the molar ratio of copper to praseodymium is 1:1; step S3: controlling the water content in the wet mixed material to be 20%-25%; step S4: successively aging, filtering and pre-extruding the wet mixed material to obtain a solid material, and extruding the solid material by an extruder to obtain a green body, and the green body is in a honeycomb shape or a column shape; step S5: drying and calcining the green body to obtain a catalyst for chlorinated organic waste gas. The catalyst for chlorinated organic waste gas is obtained by the preparation method. The application is the application of the catalyst for chlorinated organic waste gas in catalytic degradation of chlorinated organic waste gas. The catalyst prepared by the present invention has low cost, anti-chlorine poisoning, high activity, high stability and high selectivity.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas purification, and particularly relates to a catalyst for chlorinated organic waste gas, a preparation method thereof, and an application thereof. Background Art

[0002] Chlorinated organic waste gas (abbreviated as Cl-VOCs) is generated in industries such as industry, agriculture, pesticides, pharmaceuticals, and organic synthesis. Chlorinated organic waste gas is difficult to biodegrade, easily accumulates in organisms, and has the risks of carcinogenesis, teratogenesis, and mutagenesis. At present, the methods for treating organic waste gas include direct incineration method, catalytic combustion method, condensation method, biological method, photochemical oxidation method, ultraviolet photolysis method, absorption method, adsorption method, etc. Among them, the direct incineration method is often restricted due to problems such as secondary pollution (such as the generation of dioxins) and high cost. The condensation method, biological method, photochemical oxidation method, ultraviolet photolysis method, absorption method, and adsorption method have low treatment efficiency and are difficult to make the chlorinated organic waste gas meet the discharge standards; in addition, they often need to be used in combination with the destruction method. The catalytic combustion method is considered to be an efficient and low-cost treatment method, but chlorinated organic waste gas is likely to poison the catalyst and deactivate the catalyst; in addition, if the catalyst is used improperly, the catalytic combustion method will produce polychlorinated biphenyls. Polychlorinated biphenyls are precursors of dioxins, and their chemical properties are very stable and difficult to decompose in nature, belonging to persistent organic pollutants. Therefore, how to improve the catalyst in the catalytic combustion method is the key to degrading chlorinated organic waste gas.

[0003] Conventional organic waste gas catalysts mainly consist of a carrier and an active component. Among them, the carrier is a key component of the catalyst, and the commonly used carrier material for organic waste gas catalysts is cordierite. However, the production and preparation process of cordierite carrier materials is complex and the operation requirements are high, resulting in too high prices for catalyst products, which is not conducive to the sales of catalyst products and the popularization and application of organic waste gas catalytic purification technologies. In addition, the active component mostly uses precious metals such as Pt and Pd, which increases the cost of the catalyst. When catalyzing chlorinated organic waste gas, due to the strong electronegativity of chlorine, it is easily adsorbed on the active center of the catalyst to form PtOCl and PdOCl, which are difficult to desorb, causing catalyst poisoning.

[0004] Therefore, it is particularly important to develop a catalyst that can improve the stability of the catalyst, prevent the catalyst from being poisoned by chlorine, and improve the selectivity of the product chlorine or hydrogen chloride, and reduce the production of polychlorinated biphenyls. Zhang Yu et al. of East China University of Science and Technology used transition metal oxides such as iron oxide modified by sulfuric acid in the invention patent with publication number CN107008459A to improve the activity of chlorine-containing organic catalysts; Zhu Youfu used carbon nanotubes to load active components such as iron oxide in the invention patent with publication number CN107469832A to prepare a catalytic combustion catalyst for chlorine-containing organic waste gas. The iron oxides used in these methods are precursors of iron salts such as iron nitrate and iron sulfate, and the prepared catalysts have not been subjected to long-term stability experiments. They are also different in structure from the honeycomb catalysts widely used at this stage, and there is a problem of large pressure drop, which cannot be directly used in industry. The present invention intends to use iron-containing dust as an iron source to directly prepare a honeycomb catalyst with high activity, high stability and high selectivity, which can be directly used in industry.

[0005] As we all know, a large amount of iron-containing dust is produced in steel production, which contains about 40% Fe, about 30% CaO and SiO 2 The main impurities are Zn, C, Mg and other impurities. At present, the utilization of iron-containing dust is mainly based on recycling and reuse in blast furnaces, but the impurities in iron-containing dust will continue to circulate and accumulate in the blast furnace. Coupled with the continuous introduction of scrap steel and low-grade miscellaneous ores, it is easy to cause the blast furnace working conditions to deteriorate (such as throat nodules, refractory corrosion, and shortened life), affecting operation, resulting in a continuous decrease in the self-circulation digestion capacity of the blast furnace. A large amount of iron-containing dust can only be temporarily stored, which not only causes a waste of resources, but also brings secondary pollution and threatens the ecological environment. With the increasing pressure on environmental protection, the effective utilization of iron-containing dust solid waste has become a serious problem that needs to be solved urgently.

[0006] In summary, how to develop a low-cost, chlorine-poisoning-resistant, highly active, highly stable and highly selective chlorine-containing organic waste gas catalyst based on iron-containing dust and its preparation method and application are of great practical significance for the treatment of chlorine-containing organic waste gas. Summary of the invention

[0007] The present invention aims to provide a chlorine-containing organic waste gas catalyst and its preparation method and application. The specific technical scheme is as follows:

[0008] In a first aspect, the present invention provides a method for preparing a chlorine-containing organic waste gas catalyst, comprising the following steps:

[0009] Step S1, washing and filtering the iron-containing dust to obtain iron sand;

[0010] Step S2: By mass fraction, 0.5 - 2 parts of iron sand, 0.5 - 2 parts of mixed metal salts, 5 - 8.5 parts of kaolin, and 0.5 - 1 part of carrier are dry - mixed, dried, and pulverized to obtain a pulverized material; wherein, the mixed metal salts include copper salt and praseodymium salt, and the molar ratio of copper to praseodymium is 1:1;

[0011] Step S3: A binder, a pore - forming agent, and an extrusion aid are added to the pulverized material for dry - mixing to obtain a dry - mixed material; a lubricant is added to the dry - mixed material for premixing to obtain a premixed material; water is added to the premixed material in portions for wet - mixing to obtain a wet - mixed material, and an alkaline regulator is used to control the pH of the wet - mixed material to be 8 - 10; wherein, the amount of water added each time is 3% - 5% of the total mass of the premixed material, and finally the water content in the wet - mixed material is controlled to be 20% - 25%;

[0012] Step S4: The wet - mixed material is subjected to aging, filtration, and pre - extrusion treatment in sequence to obtain a solid material; the solid material is extruded by an extruder to obtain a green body, and the green body is in a honeycomb shape or a column shape;

[0013] Step S5: The green body is subjected to drying and roasting treatment to obtain a catalyst for chlorinated organic waste gas.

[0014] Optionally, in Step S2, the copper salt is copper nitrate trihydrate; the praseodymium salt is praseodymium nitrate hexahydrate;

[0015] The carrier includes nano - aluminum oxide;

[0016] The particle size of the pulverized material is 100 - 200 mesh.

[0017] Optionally, in Step S3, the alkaline regulator includes ammonia water;

[0018] The dosage of the binder is 1% of the total mass of the pulverized material, and it includes carboxymethyl cellulose;

[0019] The dosage of the pore - forming agent is 2% of the total mass of the pulverized material, and it includes at least one of urea and polyethylene glycol;

[0020] The dosage of the extrusion aid is 1% of the total mass of the pulverized material, and it includes dodecylbenzenesulfonic acid;

[0021] The dosage of the lubricant is 2% of the total mass of the dry - mixed material, and it includes talc powder.

[0022] Optionally, in Step S4, the process conditions for aging are an aging temperature of 30 - 50 °C and an aging time of 24 ± 2 h.

[0023] Optionally, in step S4, a clay kneader is used to filter and pre-extrude the aged wet mixture, and the operating temperature is not higher than 50°C.

[0024] Optionally, in step S4, the process conditions adopted by the extruder are an extrusion speed of 1±0.5 m / min, a pressure of 1-6 MPa, a temperature of 10-30°C, a vacuum degree less than -0.096 MPa, and an extrusion length of 100±50 mm.

[0025] Optionally, in step S5, the drying conditions are a drying temperature of 80±10°C and a drying time of 12±2 h; the roasting conditions are a roasting temperature of 600±20°C and a roasting time of 8±2 h.

[0026] Optionally, in step S1, the iron-containing dust is solid waste generated in steel production; the mass ratio of iron in the iron sand is not less than 45%.

[0027] In a second aspect, the present invention provides a catalyst for chlorinated organic waste gas, which is prepared by using the preparation method of the catalyst for chlorinated organic waste gas.

[0028] In a third aspect, the present invention provides an application of a catalyst for chlorinated organic waste gas, which is the application of the catalyst for chlorinated organic waste gas in catalytic degradation of chlorinated organic waste gas.

[0029] Applying the technical solution of the present invention has at least the following beneficial effects:

[0030] The catalyst for chlorinated organic waste gas prepared by the preparation method of the present invention has the best activity, selectivity and stability. Analyzed from the catalytic principle: the catalytic process of chlorinated organic waste gas by the catalyst for chlorinated organic waste gas has to go through external diffusion, internal diffusion, adsorption, catalytic reaction, desorption, internal diffusion and external diffusion. That is: the chlorinated reactants in the chlorinated organic waste gas diffuse from the gas phase main body to the outer surface of the catalyst, the chlorinated reactants diffuse from the outer surface of the catalyst to the inner surface, the chlorinated reactants are adsorbed on the active centers on the inner surface of the catalyst, and the chlorinated reactants adsorbed on the surface of the active centers are catalytically reacted to generate purified products; subsequently, the purified products are desorbed from the active centers on the inner surface of the catalyst, the purified products diffuse from the inner surface of the catalyst to the outer surface, and finally diffuse into the gas flow main body. Specifically, for the catalyst for chlorinated organic waste gas prepared by the present invention, the carrier is nano-aluminum oxide, which has a huge specific surface area and a rich pore structure. When carrying the active components, the dispersibility and stability of the active components are greatly improved. Moreover, for the catalyst for chlorinated organic waste gas prepared by the present invention, the active components are composed of composite oxides of iron, copper and praseodymium, and the active centers formed by the active components are uniformly dispersed on the carrier of the catalyst for chlorinated organic waste gas; on each active center, iron, copper and praseodymium act synergistically to ensure that the catalyst for chlorinated organic waste gas has high activity and stability. Among them, the molar ratio of copper to praseodymium is controlled to be 1:1 and used as the main active substance, and the addition of praseodymium improves the activity and stability of the catalyst; while iron and copper in the active centers can promote the reaction of chlorinated organic waste gas to generate chlorine gas, ensuring that the catalyst for chlorinated organic waste gas has high selectivity, reducing or avoiding the generation of polychlorinated biphenyl products, and at the same time, preventing the active centers from being poisoned by adsorbed chlorine. In the preparation method of the present invention, iron-containing dust is selected to provide iron, which can not only realize the resource utilization of waste, but also has important social and economic benefits.

[0031] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The following will refer to the drawings to further elaborate on the present invention in detail. Brief Description of the Drawings

[0032] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0033] Figure 1 It is a result graph of the stability test of the catalysts in Examples 1 and Comparative Examples 1, 3, 5-6 of the present invention in chlorobenzene.

[0034] Figure 2 It is a result graph of the stability test of the catalysts in Examples 1-3 of the present invention in chlorobenzene.

[0035] Figure 3XRD patterns of the catalysts prepared in Example 1 and Comparative Example 6 of the present invention. Detailed implementation manners

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0037] Example 1:

[0038] A preparation method of a catalyst for chlorinated organic waste gas, comprising the following steps:

[0039] Step S1: Wash and filter the iron-containing dust to obtain iron sand;

[0040] Step S2: By mass, 1 part of iron sand, 1.5 parts of mixed metal salts, 6.5 parts of kaolin and 1 part of carrier are dry-mixed, dried and pulverized to obtain a pulverized material; wherein, the mixed metal salts include copper salts and praseodymium salts, and the molar ratio of copper to praseodymium is 1:1;

[0041] Step S3: Add a binder, a pore-forming agent and an extrusion aid to the pulverized material for dry mixing for 30 minutes to obtain a dry-mixed material; add a lubricant to the dry-mixed material for premixing for 30 minutes to obtain a premixed material; add water to the premixed material in portions for wet mixing to obtain a wet-mixed material, and use an alkaline regulator to control the pH of the wet-mixed material to 8; wherein, the amount of water added each time is 4% of the total mass of the premixed material, and finally control the moisture content in the wet-mixed material to 23%;

[0042] Step S4: Subject the wet-mixed material to aging, filtration and pre-extrusion treatment in sequence to obtain a solid material; use an extruder to extrude the solid material to obtain a green body, and the green body is honeycomb-shaped;

[0043] Step S5: Subject the green body to drying and calcination treatment to obtain a catalyst for chlorinated organic waste gas. Before drying the green body, place it in a cardboard box with a sponge lining to facilitate protecting the shape of the green body.

[0044] In step S2, the copper salt is copper nitrate trihydrate; the praseodymium salt is praseodymium nitrate hexahydrate;

[0045] The carrier includes nano-aluminum trioxide;

[0046] The particle size of the pulverized material is 100-200 mesh.

[0047] In step S3, the alkaline regulator includes ammonia water;

[0048] The dosage of the binder is 1% of the total mass of the crushed material, and it includes carboxymethyl cellulose;

[0049] The dosage of the pore-forming agent is 2% of the total mass of the crushed material, and it includes urea and polyethylene glycol, and the mass ratio is 1:1;

[0050] The dosage of the extrusion aid is 1% of the total mass of the crushed material, and it includes dodecylbenzenesulfonic acid;

[0051] The dosage of the lubricant is 2% of the total mass of the dry-mixed material, and it includes talc powder.

[0052] In step S3, adding the lubricant and the binder separately is to prevent the lubricant from being agglomerated by the binder.

[0053] In step S4, the process conditions for aging are an aging temperature of 40 °C and an aging time of 24 h.

[0054] In step S4, a kneading machine is used to filter and pre-extrude the aged wet-mixed material, and the operating temperature is 40 °C.

[0055] In step S4, the process conditions for the extruder are an extrusion speed of 1 m / min, a pressure of 5 MPa, a temperature of 25 °C, a vacuum degree of -0.097 MPa, and an extrusion length of 100 mm.

[0056] In step S5, the drying conditions are a drying temperature of 80 °C and a drying time of 12 h; the roasting conditions are a roasting temperature of 600 °C and a roasting time of 8 h.

[0057] In step S1, the iron-containing dust is solid waste generated in the steel production of a certain steel enterprise; the substances and contents in the iron sand are as shown in Table 1 below:

[0058] Table 1 Substances and contents in the iron sand of Example 1

[0059] substance Fe and its oxides CaO <![CDATA[SiO 2 > others content / % 70 15.5 12.7 1.8

[0060] Example 2:

[0061] Different from Example 1, the dosage of iron sand is 0.5 parts, and the dosage of the mixed metal salt is 2 parts.

[0062] Example 3:

[0063] Different from Example 1, the dosage of iron sand is 2 parts, and the dosage of the mixed metal salt is 0.5 parts.

[0064] Comparative Example 1:

[0065] Different from Example 1, step S1 is cancelled, that is, the dosage of iron sand is 0.

[0066] Comparative Example 2:

[0067] Different from Example 1, the amount of iron sand used is 3 parts.

[0068] In Comparative Example 2, the experimental results show that too much iron sand is used, making it difficult for the catalyst to form. Therefore, the catalyst in Comparative Example 2 is not evaluated.

[0069] Comparative Example 3:

[0070] Different from Example 1, the amount of the mixed metal salt described in step S2 is 0.3 part.

[0071] Comparative Example 4:

[0072] Different from Example 1, the amount of the mixed metal salt described in step S2 is 3 parts.

[0073] In Comparative Example 4, the experimental results show that too much of the mixed metal salt is used, making it difficult for the catalyst to form. Therefore, the catalyst in Comparative Example 4 is not evaluated.

[0074] Comparative Example 5:

[0075] Commercially available anti-chlorine catalyst.

[0076] Comparative Example 6:

[0077] Different from Example 1, the addition order of the mixed metal salt described in step S2 is transferred to after step S5. Specifically, first, the catalyst obtained from step S5 is immersed in the mixed metal salt, and then the liquid in the honeycomb channels of the immersed catalyst is purged; dried at 80 °C for 12 h and calcined at 600 °C for 8 h to obtain a prefabricated catalyst; then, weighed, and the copper and praseodymium loading amounts in the prefabricated catalyst are calculated. If they are lower than the copper and praseodymium loading amounts in the chlorine-containing organic waste gas catalyst in Example 1, the impregnation, drying, and calcination are repeated until they are the same as the copper and praseodymium loading amounts in the chlorine-containing organic waste gas catalyst in Example 1.

[0078] The catalysts prepared in Examples 1-3 and Comparative Examples 1, 3, 5-6 were respectively subjected to activity and selectivity tests, as well as stability tests, in chlorine-containing organic waste gas chlorobenzene. The specific test methods are as follows:

[0079] (1) Activity and selectivity test method: The test conditions adopted are 1000 ppm of chlorobenzene and an airspeed GPSV = 15000 h -1 . The temperature at which chlorobenzene reaches 99% conversion rate under the action of each catalyst (i.e., T99) is measured, and the amount of by-product polychlorinated biphenyls at the T99 temperature. The test results are shown in Table 2.

[0080] (2) Stability test method: The test conditions adopted are 1000 ppm of chlorobenzene, space velocity GPSV = 15000 h -1 , and the temperature is 450 °C. The stability of each catalyst support during continuous operation for 100 h was measured. The test results are shown in Figure 1 and Figure 2 .

[0081] The test equipment used in test methods (1)-(2) is a fixed bed and a gas chromatograph detector. Among them, the gas chromatograph detector is FID, and the chromatographic column is a porapak q chromatographic column.

[0082] Table 2 shows the results of the activity and selectivity tests of the catalysts in Examples 1-3 and Comparative Examples 1, 3, 5-6 in chlorobenzene

[0083]

[0084] From the data in Table 2 and Figure 1 and Figure 2 it can be seen that:

[0085] Compared with Comparative Examples 1, 3, 5-6, the catalysts for chlorinated organic waste gas prepared in Examples 1-3 of the present invention have higher activity, selectivity and stability. Among them, the catalyst for chlorinated organic waste gas prepared in Example 1 of the present invention has the best activity, selectivity and stability, and the lowest T99.

[0086] Analyzed from the catalytic principle:

[0087] The catalytic process of the chlorine-containing organic waste gas by the chlorine-containing organic waste gas catalyst undergoes external diffusion, internal diffusion, adsorption, catalytic reaction, desorption, internal diffusion, and external diffusion. That is, the chlorine-containing reactants in the chlorine-containing organic waste gas diffuse from the gas phase main body to the outer surface of the catalyst, the chlorine-containing reactants diffuse from the outer surface of the catalyst to the inner surface, the chlorine-containing reactants are adsorbed on the active centers on the inner surface of the catalyst, and the chlorine-containing reactants adsorbed on the surface of the active centers are catalytically reacted to form purified products; subsequently, the purified products are desorbed from the active centers on the inner surface of the catalyst, the purified products diffuse from the inner surface of the catalyst to the outer surface, and finally diffuse into the gas flow main body. Specifically, the active components in the chlorine-containing organic waste gas catalysts prepared in Examples 1-3 of the present invention contain a composite oxide composed of iron, copper, and praseodymium, and the active centers formed by the active components are uniformly dispersed on the carrier of the chlorine-containing organic waste gas catalyst. Among them, iron is mainly responsible for binding with chlorine, withstanding the attack of chlorine elements, protecting copper and praseodymium, and resisting chlorine poisoning. Copper is mainly used to reduce the generation of polychlorinated biphenyls and improve the selectivity of the catalyst, while praseodymium mainly provides active sites; that is, the active components provided by the chlorine-containing organic waste gas catalysts prepared in Examples 1-3 of the present invention achieve the synergistic effect of iron, copper, and praseodymium, ensuring that the chlorine-containing organic waste gas catalyst has high activity and stability. Among them, the molar ratio of copper to praseodymium is controlled to be 1:1, which is used to provide the main active sites, assist the functions of iron and copper, and prevent the active centers from being poisoned due to the adsorption or binding of chlorine.

[0088] According to the above analysis of the catalytic principle:

[0089] In Comparative Example 1, no iron sand was added, and only copper and praseodymium played a catalytic role. The activity and stability were both reduced, the selectivity decreased, and a small amount of polychlorinated biphenyl products were formed;

[0090] In Comparative Example 3, too little copper and praseodymium were added. Since copper and praseodymium are the main active substances, too little addition results in too few active centers of the catalyst, and the activity, selectivity, and stability are significantly reduced;

[0091] Comparative Example 5 is a commercially available anti-chlorine catalyst. Although the activity is acceptable, the stability and selectivity are poor.

[0092] In Comparative Example 6, copper, praseodymium, and iron sand were added separately, making it difficult for the three metal elements of iron, copper, and praseodymium to fully combine and not being able to play the synergistic effect well, resulting in low activity and poor stability of the catalyst. However, due to the presence of the two elements of iron and copper, it can promote the reaction of the chlorine-containing organic waste gas to form chlorine gas or hydrogen chloride, making the catalyst have high selectivity.

[0093] The contents of the three metal elements of iron, copper, and praseodymium in Example 1 and Comparative Example 6 were tested by a test method. The specific test method is as follows:

[0094] Take 1 g each of the catalysts prepared in Example 1 and Comparative Example 6, and completely digest them with 20 wt% dilute nitric acid respectively for testing. The test results are shown in Table 3. Among them, the test instrument is ICP-OES PerkinElmer 8300.

[0095] Table 3 Contents of three metal elements, iron, copper, and praseodymium, in Example 1 and Comparative Example 6

[0096]

[0097]

[0098] As can be seen from Table 3, the contents of Fe, Cu, and Pr in the catalysts obtained in Example 1 and Comparative Example 6 are basically the same. This shows that the performance difference between the catalysts in Example 1 and Comparative Example 6 is not caused by the difference in the content of active elements, but by the preparation method.

[0099] Furthermore, from Figure 3 it can be seen that the catalysts in Example 1 and Comparative Example 6 both contain diffraction peaks of Fe, CaO, Fe 2 O 3 , but no diffraction peaks of species such as Cu and Pr are seen in Example 1 and Comparative Example 6. This indicates that Cu and Pr may form some amorphous species. By comparing and analyzing Example 1 and Comparative Example 6, it can be seen that the peak intensity of Fe or Fe 2 O 3 in Example 1 is significantly reduced. This is because part of the Fe or Fe 2 O 3 in Example 1 forms an amorphous crystal of a composite oxide composed of iron, copper, and praseodymium, resulting in a decrease in the amount of elemental Fe or Fe 2 O 3 , thus reducing the peak intensity. At the same time, this also indirectly explains the reasons for the anti-chlorine poisoning, high activity, high stability, and high selectivity of the catalyst prepared in Example 1. While the catalyst prepared in Comparative Example 6 only forms a composite oxide composed of copper and praseodymium, and Fe still exists in the form of elemental or Fe 2 O 3 . Fe, Cu, and Pr do not form a composite oxide well and cannot give full play to the synergistic effect, so its performance is inferior to that of Example 1.

[0100] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a catalyst for chlorine-containing organic waste gas, characterized in that, it comprises the following steps: Step S1: Clean and filter the iron-containing dust to obtain iron sand; Step S2: By mass parts, dry mix, dry and crush 0.5 - 2 parts of iron sand, 0.5 - 2 parts of mixed metal salts, 5 - 8.5 parts of kaolin and 0.5 - 1 part of a carrier to obtain a crushed material; wherein, the mixed metal salts include copper salts and praseodymium salts, and the molar ratio of copper to praseodymium is 1:1; Step S3: Add a binder, a pore-forming agent and an extrusion aid to the crushed material for dry mixing to obtain a dry mixture; add a lubricant to the dry mixture for premixing to obtain a premixed material; add water to the premixed material in portions for wet mixing to obtain a wet mixture, and use an alkaline regulator to control the pH of the wet mixture to be 8 - 10; wherein, the amount of water added each time is 3% - 5% of the total mass of the premixed material, and finally control the water content in the wet mixture to be 20% - 25%; Step S4: Subject the wet mixture to aging, filtration and pre-extrusion treatments in sequence to obtain a solid material; use an extruder to extrude the solid material to obtain a green body, and the green body is in a honeycomb shape or a column shape; Step S5: Dry and calcine the green body to obtain a catalyst for chlorine-containing organic waste gas.

2. The preparation method of the catalyst for chlorine-containing organic waste gas according to claim 1, characterized in that, in Step S2, the copper salt is copper nitrate trihydrate; the praseodymium salt is praseodymium nitrate hexahydrate; the carrier includes nano-aluminum trioxide; the particle size of the crushed material is 100 - 200 mesh.

3. The preparation method of the catalyst for chlorine-containing organic waste gas according to claim 1, characterized in that, in Step S3, the alkaline regulator includes ammonia water; the dosage of the binder is 1% of the total mass of the crushed material, and it includes carboxymethyl cellulose; the dosage of the pore-forming agent is 2% of the total mass of the crushed material, and it includes at least one of urea and polyethylene glycol; the dosage of the extrusion aid is 1% of the total mass of the crushed material, and it includes dodecylbenzenesulfonic acid; the dosage of the lubricant is 2% of the total mass of the dry mixture, and it includes talcum powder.

4. The preparation method of the catalyst for chlorine-containing organic waste gas according to claim 1, characterized in that, in Step S4, the process conditions for aging are an aging temperature of 30 - 50°C and an aging time of 24 ± 2 h.

5. The preparation method of the catalyst for chlorine-containing organic waste gas according to claim 1, characterized in that, in Step S4, use a clay kneader to filter and pre-extrude the aged wet mixture, and the operating temperature is not higher than 50°C.

6. The preparation method of the catalyst for chlorine-containing organic waste gas according to claim 1, characterized in that, in Step S4, the process conditions of the extruder are an extrusion speed of 1 ± 0.5 m / min, a pressure of 1 - 6 MPa, a temperature of 10 - 30°C, a vacuum degree less than -0.096 MPa, and an extrusion length of 100 ± 50 mm.

7. The preparation method of the catalyst for chlorine-containing organic waste gas according to claim 1, characterized in that, In step S5, the drying conditions adopted are a drying temperature of 80 ± 10 °C and a drying time of 12 ± 2 h; the calcination conditions adopted are a calcination temperature of 600 ± 20 °C and a calcination time of 8 ± 2 h.

8. The method for preparing a catalyst for chlorinated organic waste gas according to any one of claims 1-7, characterized in that, in step S1, the iron-containing dust is solid waste generated in steel production; the mass proportion of iron in the iron sand is not less than 45%.

9. A catalyst for chlorinated organic waste gas, characterized in that, it is prepared by using the method for preparing a catalyst for chlorinated organic waste gas according to claim 8.

10. An application of a catalyst for chlorinated organic waste gas, characterized in that, it is the application of the catalyst for chlorinated organic waste gas according to claim 9 in catalytic degradation of chlorinated organic waste gas.

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