A catalyst for catalytic combustion of chlorine-containing organic matter and a preparation method and application thereof

Abstract

The application discloses a catalyst for catalytic combustion of chlorine-containing organic matters and a preparation method and application thereof, and belongs to the technical field of environmental protection catalysts. In the application, the composite oxide active component is loaded on a molecular sieve through an impregnation method, and then the noble metal active component is adsorbed on the surface of the composite oxide active component through an electrostatic adsorption method, so that the noble metal is stabilized by using the strong interaction between the noble metal and the oxide, the utilization rate of the noble metal catalyst is improved, the activity and stability of the catalytic combustion of the chlorine-containing organic waste gas are improved, and the industrialization of the treatment of the chlorine-containing volatile organic matters by the catalytic combustion has important significance.

Description

Technical Field

[0001] This invention belongs to the field of environmental catalyst technology, and more specifically, relates to a catalyst for the catalytic combustion of chlorine-containing organic compounds, its preparation method, and its application. Background Technology

[0002] Chlorinated volatile organic compounds (VOCs) are widely used in industries such as pharmaceuticals, pesticides, and coatings, and are the main pollutants in the chlorinated organic waste gases emitted by these enterprises. Typical VOCs include dichloromethane, trichloromethane, dichloroethane, trichloroethylene, tetrachloroethylene, and chlorobenzene. VOCs not only cause low-altitude ozone pollution and trigger photochemical smog, severely polluting the atmospheric environment, but also possess characteristics such as being difficult to biodegrade and being teratogenic and carcinogenic, threatening human health.

[0003] Developing end-of-pipe treatment technologies is of significant practical importance for controlling chlorinated volatile organic compound (VOC) pollution. Currently, end-of-pipe treatment of VOCs mainly includes incineration, adsorption / absorption, and catalytic combustion. Among these, catalytic combustion, which oxidizes VOCs into carbon dioxide, water, hydrogen chloride, and chlorine under specific temperature and catalyst conditions, offers advantages such as mild conditions, low secondary pollution, and low energy consumption, making it one of the most promising end-of-pipe treatment technologies. The key to realizing this technology lies in the development of highly efficient and stable catalysts.

[0004] A search revealed that Chinese invention patent application CN103357415A, published on October 23, 2013, discloses a catalyst for the catalytic combustion of chlorinated organic waste gas. This catalyst does not contain precious metals and is composed of nickel oxide supported on TiO2, Al2O3, ZrO2, or SiO2, exhibiting low-temperature catalytic combustion efficiency for chlorinated volatile organic compounds. Chinese invention patent application CN107008459A, published on August 4, 2017, discloses a catalyst for the low-temperature catalytic combustion of chlorinated organic compounds, its preparation method, and its application. This catalyst is a sulfuric acid-modified transition metal oxide, exhibiting catalytic combustion activity for chlorinated aliphatic hydrocarbons and chlorinated aromatic hydrocarbons.

[0005] For example, Chinese invention patent application CN107469832A, published on December 15, 2017, discloses a catalyst for the catalytic combustion of chlorinated organic waste gas and its preparation method. The catalyst is a high specific surface area carbon nanotube-supported iron oxide and alkaline earth metal material, capable of completely catalyzing the combustion and degradation of chlorinated volatile organic compounds within a temperature range of 350-400℃. Chinese invention patent application CN109967085A, published on July 5, 2019, discloses a microfiber composite molecular sieve membrane catalyst for the catalytic combustion of chlorinated volatile organic compounds, its preparation method, and its application. In this method, a vanadium-modified microfiber composite molecular sieve membrane is prepared using vapor deposition and applied to the catalytic combustion of chlorinated volatile organic compounds, effectively reducing the generation of chlorinated byproducts. Chinese invention patent application CN112108191A, published on December 22, 2020, discloses a supported ruthenium-cobalt alloy nanocatalyst for the low-temperature catalytic combustion of 1,2-dichloroethane. The supported ruthenium-cobalt alloy nanocatalyst was prepared using a soft template-solvent thermal method and an ion exchange method, achieving good low-temperature catalytic combustion performance for 1,2-dichloroethane. Chinese invention patent application CN112682806A, published on April 20, 2021, discloses a method for the catalytic combustion and elimination of chlorine-containing volatile organic compounds. This method uses a hexaaluminate and pyrochlore-type composite oxide to catalyze the combustion and degradation of chlorine-containing volatile organic compounds, achieving catalytic combustion degradation within the temperature range of 500–1000℃ without the need for frequent regeneration.

[0006] Currently, most catalytic combustion catalysts for chlorinated organic waste gases primarily consist of transition metal oxides or noble metals as their active components. Oxides exhibit poor activity but good stability and are not prone to deactivation; noble metals show better activity but require larger quantities and are more expensive, and are prone to agglomeration and deactivation. Furthermore, noble metals supported on transition metal oxides have low dispersion, limiting the exposure of active components. Therefore, there is a need to develop a catalyst with high activity and high stability. Summary of the Invention

[0007] 1. The problem to be solved

[0008] To address the problems of poor stability and insufficient catalytic activity in existing catalysts used for the catalytic combustion of chlorinated organic waste gases, this invention provides a catalyst for the catalytic combustion of chlorinated organic compounds, its preparation method, and its application. This invention employs an impregnation method to load a composite oxide active component onto a molecular sieve, followed by electrostatic adsorption to adsorb a noble metal active component onto the surface of the composite oxide active component. The strong interaction between the noble metal and the oxide stabilizes the noble metal, improving its catalytic utilization rate and thus enhancing the catalytic combustion performance of chlorinated volatile organic compounds.

[0009] 2. Technical Solution

[0010] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0011] The present invention provides a catalyst for the catalytic combustion of chlorinated organic compounds, comprising a support and an active component, wherein the active component includes an oxide active component and a noble metal active component, the oxide active component being supported on the support and the noble metal active component being supported on the oxide active component; wherein the oxide active component includes cerium oxide and an auxiliary metal oxide, the auxiliary metal being one or more of Cu, Cr, and Co, and the noble metal active component being one or two of Pt and Pd.

[0012] Preferably, the carrier is HZSM-5 molecular sieve.

[0013] Preferably, the loading of the oxide active component is 10% to 25% of the carrier mass, wherein the mass ratio of cerium oxide to auxiliary metal oxide is 1:1.

[0014] Preferably, the loading of the noble metal active component is 0.001% to 0.2% of the carrier mass.

[0015] A method for preparing a catalyst for the catalytic combustion of chlorinated organic compounds according to the present invention includes the following steps:

[0016] S10. Using the impregnation method, the support is dispersed in a solution containing the oxide active component precursor, mixed and stirred, dried and then calcined to obtain an intermediate in which the oxide active component is loaded on the support.

[0017] S20. Using electrostatic adsorption, the intermediate is dispersed in a solution containing a precursor of noble metal active components. The pH is adjusted and the mixture is stirred to allow the noble metal active components to be adsorbed on the surface of the oxide active components. After drying, the mixture is calcined to obtain a catalyst for the catalytic combustion of chlorine-containing organic compounds.

[0018] Preferably, in step S10, the precursor of the oxide active component is cerium nitrate and an auxiliary metal nitrate in a mass ratio of 1:1, the auxiliary metal is one or more of Cu, Cr, and Co, and the precursor of the noble metal active component is one or both of chloropalladic acid and chloroplatinic acid.

[0019] Preferably, the specific process of step S10 is as follows: a certain amount of oxide active component precursor is dissolved in water to obtain a solution containing oxide active component precursor, HZSM-5 molecular sieve raw powder is added to it and mixed and stirred for 4 hours, evaporated and dried at 80℃~120℃, and then calcined at 400℃~600℃ in air atmosphere for 3 hours to obtain an intermediate with oxide active component loaded on HZSM-5 molecular sieve.

[0020] Preferably, the specific process of step S20 is as follows: a certain amount of noble metal active component precursor is dissolved in water to obtain a solution containing noble metal active component precursor, an intermediate is added to it, the pH is adjusted to 3-5 and mixed and stirred so that the noble metal active component is adsorbed on the surface of the oxide active component, filtered and washed, dried at 80℃-120℃, and calcined at 400℃-600℃ for 3 hours in an air atmosphere to obtain a catalyst for catalytic combustion of chlorine-containing organic compounds.

[0021] The application of the catalyst of the present invention or the catalyst prepared by the preparation method of the present invention in the catalytic combustion of chlorinated organic waste gas includes the following specific application methods: contacting the catalyst with chlorinated organic waste gas to undergo a catalytic reaction to generate carbon dioxide, water, hydrogen chloride and chlorine, wherein the concentration of chlorinated organic compounds in the chlorinated organic waste gas is 100 to 2000 ppm.

[0022] Preferably, the reaction temperature of the catalytic reaction is 200℃~300℃, and the volume hourly space velocity of the chlorinated organic waste gas is 500~30000h. -1 .

[0023] 3. Beneficial effects

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) The catalyst of the present invention for catalytic combustion of chlorinated organic compounds has an oxide active component loaded on a support and a precious metal active component loaded on a composite oxide active component. This overcomes the problems of conventional one-step impregnation method, where some precious metals are dispersed on the surface of the support, resulting in unstable precious metal particles that are easy to agglomerate and reduce catalytic efficiency, and another part of the precious metals form a solid solution with the oxide active component and are located inside the particles, which cannot contact the waste gas and result in low utilization of precious metals.

[0026] (2) A method for preparing a catalyst for catalytic combustion of chlorinated organic compounds according to the present invention, wherein the catalyst is constructed by tightly binding three components, which enables waste gas molecules to be broken down into small molecules at the same position and then rapidly oxidized and decomposed into harmless molecules.

[0027] (3) A method for preparing a catalyst for catalytic combustion of chlorinated organic compounds according to the present invention uses HZSM-5 molecular sieve as a carrier, utilizes the surface strong acid effect to crack the difficult-to-degrade waste gas into easily decomposable small molecules, uses impregnation method to load oxides + electrostatic adsorption method to load noble metals, so that all the noble metals are located on the surface of oxides, and uses the strong interaction between noble metals and oxides to stabilize noble metal particles and improve the catalytic utilization efficiency of noble metals.

[0028] (4) The catalyst of the present invention for catalytic combustion of chlorinated organic compounds has good catalytic combustion performance for various chlorinated volatile organic compounds in the treatment of chlorinated volatile organic compounds. It can significantly reduce the reaction temperature and prolong the catalytic stability time, which is of great significance for the industrialization of catalytic combustion treatment of chlorinated volatile organic compounds. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a method for preparing a catalyst for the catalytic combustion of chlorine-containing organic compounds according to the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments.

[0031] like Figure 1 As shown, a method for preparing a catalyst for the catalytic combustion of chlorinated organic compounds according to the present invention includes the following steps:

[0032] S10. A certain amount of oxide active component precursor is dissolved in water to obtain a solution containing oxide active component precursor. Using an impregnation method, the carrier HZSM-5 molecular sieve powder is dispersed in the solution containing oxide active component precursor and stirred for 4 hours. After evaporation and drying at 80℃~120℃, it is calcined at 400℃~600℃ for 3 hours in an air atmosphere to obtain an intermediate with oxide active component loaded on HZSM-5 molecular sieve. The oxide active component precursor is cerium nitrate and auxiliary metal nitrate in a mass ratio of 1:1. The auxiliary metal is one or more of Cu, Cr, and Co.

[0033] S20. A certain amount of noble metal active component precursor is dissolved in water to obtain a solution containing the noble metal active component precursor. An intermediate is dispersed in the solution containing the noble metal active component precursor using electrostatic adsorption. The pH is adjusted to 3-5 and the mixture is stirred to allow the noble metal active component to adsorb onto the surface of the oxide active component. The mixture is filtered and washed, dried at 80-120℃, and then calcined at 400-600℃ for 3 hours in air to obtain a catalyst for the catalytic combustion of chlorinated organic compounds. The noble metal active component precursor is one or both of chloropalladium acid and chloroplatinic acid. The catalyst for the catalytic combustion of chlorinated organic compounds prepared by the above method has an oxide active component loading of 10%-25% of the support mass and a noble metal active component loading of 0.001%-0.2% of the support mass.

[0034] It should be noted that the catalyst of this invention exhibits excellent catalytic combustion performance for various chlorine-containing volatile organic compounds (VOCs), significantly reducing reaction temperature and extending catalytic stability time. Its catalyst performance surpasses that of any single component or combination of two components from molecular sieves, composite oxides, and noble metals, and is superior to catalysts with the same composition as those described in this invention but prepared solely by a one-step impregnation method. Furthermore, the HZSM-5 molecular sieve support used in the catalyst of this invention can utilize its surface acidity to accelerate the decomposition of chlorine-containing VOCs, increasing the reaction rate. This not only reduces the amount of noble metals used and catalyst costs, but also fully leverages the advantages of transition metal oxides and noble metals, improving the activity and stability of catalytic combustion of chlorine-containing organic waste gas. This is of great significance for the industrialization of catalytic combustion treatment of chlorine-containing VOCs.

[0035] Example 1

[0036] This embodiment describes a method for preparing a catalyst for the catalytic combustion of chlorinated organic compounds. HZSM-5 molecular sieve is selected as the support, and the active components are 10 wt.% cerium oxide, 10 wt.% copper oxide, and 0.01 wt.% platinum (denoted as 10Ce10Cu / 0.01Pt). The specific preparation method includes the following steps:

[0037] S10. Using the impregnation method, 2.52g of cerium nitrate and 3.03g of copper nitrate were dissolved in 50mL of deionized water according to the composite oxide loading. 10g of HZSM-5 molecular sieve powder was added and mixed and stirred for 4 hours. The mixture was evaporated and dried at 80℃ and then calcined at 500℃ in air for 3 hours to obtain an intermediate in which the active component of the composite oxide is loaded on HZSM-5 molecular sieve.

[0038] S20. Using electrostatic adsorption, 2.65 mg of chloroplatinic acid was dissolved in deionized water according to the noble metal loading. Dilute hydrochloric acid was added dropwise to adjust the pH of the solution to 3.5. The intermediate powder obtained in step S10 was added to the solution and mixed and stirred. The mixture was filtered and washed, dried at 110°C, and then calcined at 550°C in air for 3 hours to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

[0039] The catalyst prepared above was used for a catalytic combustion reaction, and its catalytic performance was tested. In this example, the chlorine-containing volatile organic compound tested was dichloromethane at a concentration of 1000 ppm and a space velocity of 15000 h⁻¹. -1 The specific steps are as follows:

[0040] (1) The catalyst is placed in an atmospheric pressure fixed-bed reactor, and the catalytic combustion reaction is carried out in the atmospheric pressure fixed-bed reactor. The reactor is a quartz glass tube with an inner diameter of 22 mm, and the amount of catalyst used is 1 cm³. 3 ;

[0041] (2) Prepare a reaction gas containing chlorine volatile organic compounds with 20% oxygen and the remainder nitrogen. Pass the gas through the catalyst at a certain flow rate according to the space velocity. Raise the fixed bed temperature from room temperature to 300°C to carry out the reaction and collect the tail gas. Analyze the tail gas on gas chromatography to determine the initial conversion rate of chlorine volatile organic compounds and the selectivity of various products and by-products. Measure the reaction temperature T90 when the conversion rate reaches 90%. The smaller the T90, the better the catalytic activity.

[0042] (3) The reaction temperature was set at 300℃ and the reaction was carried out continuously for 120 hours. The time during which the catalyst could maintain a conversion rate of more than 90% at the beginning of the reaction was tested. The longer the stability time, the better the stability. The test results are shown in Table 1.

[0043] The test results of Example 1 in Table 1 show that the catalyst prepared in Example 1 can remove more than 90% of chlorine-containing volatile organic compounds in the waste gas at 240℃ under given reaction conditions, and can maintain an initial conversion rate of more than 90% at 300℃ and a reaction time of 120h, demonstrating excellent catalytic activity and stability.

[0044] Comparative Example 1

[0045] The basic content of this comparative example is the same as that of Example 1, except that: this comparative example uses HZSM-5 molecular sieve as the support, and the active components are 10 wt.% cerium oxide and 0.01 wt.% platinum (denoted as 10Ce / 0.01Pt), without any auxiliary metal oxide active components. The specific preparation method includes the following steps:

[0046] S10. Using the impregnation method, the corresponding mass of cerium nitrate is dissolved in deionized water according to the oxide loading, HZSM-5 molecular sieve powder is added and mixed and stirred for 4 hours. After the mixture is evaporated and dried at 80°C, it is calcined at 500°C in air atmosphere for 3 hours to obtain an intermediate with oxide active components loaded on HZSM-5 molecular sieve.

[0047] S20. Using electrostatic adsorption, dissolve the corresponding mass of chloroplatinic acid in deionized water according to the noble metal loading, add dilute hydrochloric acid to adjust the pH of the solution to 3.5, add the intermediate powder obtained in step S10 and mix and stir, filter and wash, dry at 110°C, and calcine at 550°C in air atmosphere for 3 hours to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

[0048] The catalyst prepared in this comparative example was used for a catalytic combustion reaction to test its performance. The chlorine-containing volatile organic compound tested was dichloromethane at a concentration of 1000 ppm and a space velocity of 15000 h⁻¹. -1 The test results are shown in Table 1.

[0049] The test results of Comparative Example 1 in Table 1 show that, under the same reaction conditions, the catalyst prepared in Comparative Example 1 can only remove 90% of the chlorine-containing volatile organic compounds when the reaction temperature reaches 285℃, and its activity drops to below 90% of the initial conversion rate after reacting at 300℃ for 72 hours. The catalytic activity and stability are significantly lower than those of the catalyst in Example 1.

[0050] Comparative Example 2

[0051] The basic content of this comparative example is the same as that of Example 1, except that: this comparative example uses HZSM-5 molecular sieve as the support, and the active components are 10 wt.% cerium oxide and 10 wt.% copper oxide (denoted as 10Ce10Cu), without any noble metal active components. The specific preparation method is as follows: using the impregnation method, according to the composite oxide loading, the corresponding mass of cerium nitrate and copper nitrate are dissolved in deionized water, HZSM-5 molecular sieve raw powder is added to it and mixed and stirred for 4 hours, the mixture is evaporated and dried at 80°C, and then calcined at 550°C in air atmosphere for 3 hours to obtain the catalyst.

[0052] The catalyst prepared in this comparative example was used for a catalytic combustion reaction to test its performance. The chlorine-containing volatile organic compound tested was dichloromethane at a concentration of 1000 ppm and a space velocity of 15000 h⁻¹. -1 The test results are shown in Table 1.

[0053] The test results of Comparative Example 2 in Table 1 show that, under the same reaction conditions, the catalyst prepared in Comparative Example 2 can only remove 90% of the chlorine-containing volatile organic compounds when the reaction temperature reaches 278°C. Its catalytic activity is significantly lower than that of the catalyst in Example 1, but it can still maintain an initial conversion rate of 90% after reacting at 300°C for 120 hours.

[0054] Comparative Example 3

[0055] The basic content of this comparative example is the same as that of Example 1, except that: this comparative example uses HZSM-5 molecular sieve as the support, and the active components are 10 wt.% copper oxide and 0.01 wt.% platinum (denoted as 10Cu / 0.01Pt), without cerium oxide active components. The specific preparation method includes the following steps:

[0056] S10. Using the impregnation method, copper nitrate of the corresponding mass is dissolved in deionized water according to the oxide loading, HZSM-5 molecular sieve powder is added and mixed and stirred for 4 hours. After the mixture is evaporated and dried at 80°C, it is calcined at 500°C in air for 3 hours to obtain an intermediate with oxide active components loaded on HZSM-5 molecular sieve.

[0057] S20. Using electrostatic adsorption, dissolve the corresponding mass of chloroplatinic acid in deionized water according to the noble metal loading, add dilute hydrochloric acid to adjust the pH of the solution to 3.5, add the intermediate powder obtained in step S10 and mix and stir, filter and wash, dry at 110°C, and calcine at 550°C in air atmosphere for 3 hours to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

[0058] The catalyst prepared in this comparative example was used for a catalytic combustion reaction to test its performance. The chlorine-containing volatile organic compound tested was dichloromethane at a concentration of 1000 ppm and a space velocity of 15000 h⁻¹. -1 The test results are shown in Table 1.

[0059] The test results of Comparative Example 3 in Table 1 show that, under the same reaction conditions, the catalyst prepared in Comparative Example 3 can only remove 90% of the chlorine-containing volatile organic compounds when the reaction temperature reaches 276°C, and its activity drops to below 90% of the initial conversion rate after reacting at 300°C for 38 hours. The catalytic activity and stability are significantly lower than those of the catalyst in Example 1.

[0060] Comparative Example 4

[0061] The basic content of this comparative example is the same as that of Example 1, except that: this comparative example uses Silicalite-1 molecular sieve as the carrier, and the active components are 10 wt.% cerium oxide, 10 wt.% copper oxide, and 0.01 wt.% platinum (denoted as 10Ce10Cu / 0.01Pt-Si). Pure silica Silicalite-1 molecular sieve has the same structure as HZSM-5 molecular sieve but its surface is not acidic.

[0062] The specific preparation method includes the following steps:

[0063] S10. Using the impregnation method, according to the loading of the composite oxide, the corresponding mass of cerium nitrate and copper nitrate are dissolved in deionized water, Silicalite-1 molecular sieve powder is added and mixed and stirred for 4 hours. After the mixture is evaporated and dried at 80°C, it is calcined at 500°C in air atmosphere for 3 hours to obtain the intermediate with the active component of the composite oxide loaded on Silicalite-1 molecular sieve.

[0064] S20. Using electrostatic adsorption, dissolve the corresponding mass of chloroplatinic acid in deionized water according to the noble metal loading, add dilute hydrochloric acid to adjust the pH of the solution to 3.5, add the intermediate powder obtained in step S10 and mix and stir, filter and wash, dry at 110°C, and calcine at 550°C in air atmosphere for 3 hours to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

[0065] The catalyst prepared in this comparative example was used for a catalytic combustion reaction to test its performance. The chlorine-containing volatile organic compound tested was dichloromethane at a concentration of 1000 ppm and a space velocity of 15000 h⁻¹. -1 The test results are shown in Table 1.

[0066] The test results of Comparative Example 4 in Table 1 show that, under the same reaction conditions, the catalyst prepared in Comparative Example 4 can only remove 90% of the chlorine-containing volatile organic compounds when the reaction temperature reaches 271°C. Its catalytic activity is significantly lower than that of the catalyst in Example 1, but it can still maintain an initial conversion rate of 90% after reacting at 300°C for 120 hours.

[0067] Comparative Example 5

[0068] The basic content of this comparative example is the same as that of Example 1, except that: HZSM-5 molecular sieve is selected as the carrier in this comparative example, and the active components are 10 wt.% cerium oxide, 10 wt.% copper oxide, and 0.01 wt.% platinum (denoted as 10Ce10Cu0.01Pt-1). Cerium oxide, copper oxide and the noble metal platinum are loaded simultaneously by a one-step impregnation method.

[0069] The specific preparation method is as follows: according to the loading of composite oxide and noble metal, the corresponding mass of cerium nitrate, copper nitrate and chloroplatinic acid are dissolved in deionized water, HZSM-5 molecular sieve powder is added and mixed and stirred for 4 hours, the mixture is evaporated and dried at 80°C, and then calcined at 550°C in air atmosphere for 3 hours to obtain the catalyst.

[0070] The catalyst prepared in this comparative example was used for a catalytic combustion reaction to test its performance. The chlorine-containing volatile organic compound tested was dichloromethane at a concentration of 1000 ppm and a space velocity of 15000 h⁻¹. -1 The test results are shown in Table 1.

[0071] The test results of Comparative Example 5 in Table 1 show that, under the same reaction conditions, the catalyst prepared in Comparative Example 5 can only remove 90% of the chlorine-containing volatile organic compounds when the reaction temperature reaches 265°C because the noble metal active components are mainly dispersed inside the composite oxide active components rather than on the surface. Furthermore, after reacting at 300°C for 96 hours, the activity drops to below 90% of the initial conversion rate. Both the catalytic activity and stability are significantly lower than those of the catalyst in Example 1.

[0072] Comparative Example 6

[0073] The basic content of this comparative example is the same as that of Example 1, except that: HZSM-5 molecular sieve is selected as the support in this comparative example, and the active components are 10 wt.% cerium oxide, 10 wt.% copper oxide, and 0.01 wt.% platinum (denoted as 10Ce10Cu / 0.01Pt-2). A two-step impregnation method is used to load the composite oxide active component and the noble metal active component respectively. The specific preparation method includes the following steps:

[0074] S10. Using the impregnation method, according to the loading of the composite oxide, the corresponding mass of cerium nitrate and copper nitrate are dissolved in deionized water, HZSM-5 molecular sieve powder is added and mixed and stirred for 4 hours. After the mixture is evaporated and dried at 80°C, it is calcined at 500°C in air atmosphere for 3 hours to obtain the intermediate with the active component of the composite oxide loaded on HZSM-5 molecular sieve.

[0075] S20. Using the impregnation method again, dissolve the corresponding mass of chloroplatinic acid in deionized water according to the noble metal loading, add the intermediate powder obtained in step S10 and mix and stir, filter and wash, dry at 110°C, and calcine at 550°C in air atmosphere for 3 hours to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

[0076] The catalyst prepared in this comparative example was used for a catalytic combustion reaction to test its performance. The chlorine-containing volatile organic compound tested was dichloromethane at a concentration of 1000 ppm and a space velocity of 15000 h⁻¹. -1 The test results are shown in Table 1.

[0077] The test results of Comparative Example 6 in Table 1 show that, under the same reaction conditions, the catalyst prepared in Comparative Example 6 can only remove 90% of the chlorine-containing volatile organic compounds when the reaction temperature reaches 270°C because the noble metal active component, namely chloroplatinate ions, is simultaneously loaded on the surface of the molecular sieve and the surface of the oxide active component. Furthermore, after reacting at 300°C for 88 hours, the activity drops to below 90% of the initial conversion rate. Both the catalytic activity and stability are significantly lower than those of the catalyst in Example 1.

[0078] Comparative Example 7

[0079] The basic content of this comparative example is the same as that of Example 1, except that: HZSM-5 molecular sieve is selected as the carrier in this comparative example, and the active components are 2 wt.% cerium oxide, 2 wt.% copper oxide, and 0.01 wt.% platinum (denoted as 2Ce2Cu / 0.01Pt). The loading of cerium oxide and copper oxide is relatively low.

[0080] The specific preparation method includes the following steps:

[0081] S10. Using the impregnation method, according to the composite oxide loading, the corresponding mass of cerium nitrate and chromium nitrate are dissolved in deionized water, HZSM-5 molecular sieve powder is added and mixed and stirred for 4 hours. After the mixture is evaporated and dried at 80°C, it is calcined at 500°C in air atmosphere for 3 hours to obtain the intermediate with the active component of the composite oxide loaded on HZSM-5 molecular sieve.

[0082] S20. Using electrostatic adsorption, chloroplatinic acid of the corresponding mass is dissolved in deionized water according to the noble metal loading. Dilute hydrochloric acid is added dropwise to adjust the pH of the solution to 3.5. Intermediate powder is added and mixed and stirred. After filtration and washing, the solution is dried at 110°C and then calcined at 550°C in air for 3 hours to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

[0083] The catalyst prepared in this comparative example was used for a catalytic combustion reaction to test its performance. The chlorine-containing volatile organic compound tested was dichloromethane at a concentration of 1000 ppm and a space velocity of 15000 h⁻¹. -1 The test results are shown in Table 1.

[0084] The test results of Comparative Example 7 in Table 1 show that, under the same reaction conditions, the catalyst prepared in Comparative Example 7 can only remove 90% of the chlorine-containing volatile organic compounds when the reaction temperature reaches 279°C. Its catalytic activity is significantly lower than that of the catalyst in Example 1, but it can still maintain an initial conversion rate of 90% after reacting at 300°C for 120 hours.

[0085] Comparative Example 8

[0086] The basic content of this comparative example is the same as that of Example 1, except that: HZSM-5 molecular sieve is selected as the carrier in this comparative example, and the active components are 15 wt.% cerium oxide, 15 wt.% copper oxide, and 0.01 wt.% platinum (denoted as 15Ce15Cu / 0.01Pt). The loading of cerium oxide and copper oxide is relatively high.

[0087] The specific preparation method includes the following steps:

[0088] S10. Using the impregnation method, according to the composite oxide loading, the corresponding mass of cerium nitrate and chromium nitrate are dissolved in deionized water, HZSM-5 molecular sieve powder is added and mixed and stirred for 4 hours. After the mixture is evaporated and dried at 80°C, it is calcined at 500°C in air atmosphere for 3 hours to obtain the intermediate with the active component of the composite oxide loaded on HZSM-5 molecular sieve.

[0089] S20. Using electrostatic adsorption, chloroplatinic acid of the corresponding mass is dissolved in deionized water according to the noble metal loading. Dilute hydrochloric acid is added dropwise to adjust the pH of the solution to 3.5. Intermediate powder is added and mixed and stirred. After filtration and washing, the solution is dried at 110°C and then calcined at 550°C in air for 3 hours to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

[0090] The catalyst prepared in this comparative example was used for a catalytic combustion reaction to test its performance. The chlorine-containing volatile organic compound tested was dichloromethane at a concentration of 1000 ppm and a space velocity of 15000 h⁻¹. -1 The test results are shown in Table 1.

[0091] The test results of Comparative Example 8 in Table 1 show that, under the same reaction conditions, the catalyst prepared in Comparative Example 8 can only remove 90% of the chlorine-containing volatile organic compounds when the reaction temperature reaches 265℃. Its catalytic activity is significantly lower than that of the catalyst in Example 1. However, it can still maintain an initial conversion rate of 90% after reacting at 300℃ for 120h.

[0092] Table 1. Catalytic performance test results of the catalysts prepared in Example 1 and Comparative Examples 1-8

[0093] Example 1 HZSM-5 molecular sieve 10Ce10Cu / 0.01Pt dichloromethane 240℃ 120h Comparative Example 1 HZSM-5 molecular sieve 10Ce / 0.01Pt dichloromethane 285℃ 72h Comparative Example 2 HZSM-5 molecular sieve 10Ce / 10Cu dichloromethane 278℃ 120h Comparative Example 3 HZSM-5 molecular sieve 10Cu / 0.01Pt dichloromethane 276℃ 38h Comparative Example 4 Silicalite-1 10Ce10Cu / 0.01Pt-S1 dichloromethane 271℃ 120h Comparative Example 5 HZSM-5 molecular sieve 10Ce10Cu0.01Pt-1 dichloromethane 265℃ 96h Comparative Example 6 HZSM-5 molecular sieve 10Ce10Cu0.01Pt-2 dichloromethane 270℃ 88h Comparative Example 7 HZSM-5 molecular sieve 2Ce2Cu / 0.01Pt dichloromethane 279℃ 120h Comparative Example 8 HZSM-5 molecular sieve 15Ce15Cu / 0.01Pt dichloromethane 265℃ 120h

[0094] Example 2

[0095] The basic content of this embodiment is the same as that of Embodiment 1, except that: HZSM-5 molecular sieve is selected as the support, and the active components are 10 wt.% cerium oxide, 10 wt.% chromium oxide, and 0.01 wt.% platinum (denoted as 10Ce10Cr / 0.1Pt). The specific preparation method includes the following steps:

[0096] S10. Using the impregnation method, according to the composite oxide loading, the corresponding mass of cerium nitrate and chromium nitrate are dissolved in deionized water, HZSM-5 molecular sieve powder is added and mixed and stirred for 4 hours. After the mixture is evaporated and dried at 80°C, it is calcined at 500°C in air atmosphere for 3 hours to obtain the intermediate with the active component of the composite oxide loaded on HZSM-5 molecular sieve.

[0097] S20. Using electrostatic adsorption, dissolve the corresponding mass of chloroplatinic acid in deionized water according to the noble metal loading, add dilute hydrochloric acid to adjust the pH of the solution to 3.5, add the intermediate powder obtained in step S10 and mix and stir, filter and wash, dry at 110°C, and calcine at 550°C in air atmosphere for 3 hours to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

[0098] The catalyst prepared in this embodiment was used for a catalytic combustion reaction, and its performance was tested. The chlorine-containing volatile organic compound tested was dichloromethane at a concentration of 500 ppm and a space velocity of 15000 h⁻¹. -1 The T90 temperature is 243℃, and the reaction stability time at 300℃ is 120h.

[0099] Example 3

[0100] The basic content of this embodiment is the same as that of Embodiment 1, except that: HZSM-5 molecular sieve is selected as the support, and the active components are 10 wt.% cerium oxide, 10 wt.% cobalt oxide, and 0.01 wt.% palladium (denoted as 10Ce10Co / 0.1Pd). The specific preparation method includes the following steps:

[0101] S10. Using the impregnation method, according to the loading of the composite oxide, the corresponding mass of cerium nitrate and cobalt nitrate are dissolved in deionized water, HZSM-5 molecular sieve powder is added and mixed and stirred for 4 hours. After the mixture is evaporated and dried at 80°C, it is calcined at 500°C in air atmosphere for 3 hours to obtain the intermediate with the active component of the composite oxide loaded on HZSM-5 molecular sieve.

[0102] S20. Using electrostatic adsorption, dissolve the corresponding mass of chloropalladium acid in deionized water according to the noble metal loading, add dilute hydrochloric acid to adjust the pH of the solution to 3.5, add the intermediate powder obtained in step S10 and mix and stir, filter and wash, dry at 110°C, and calcine at 550°C in air atmosphere for 3 hours to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

[0103] The catalyst prepared in this embodiment was used in a catalytic combustion reaction to test its performance. The chlorine-containing volatile organic compound tested was dichloroethane at a concentration of 1000 ppm and a space velocity of 15000 h⁻¹. -1 The T90 temperature is 236℃, and the reaction stability time at 300℃ is 120h.

[0104] Example 4

[0105] The basic content of this embodiment is the same as that of Embodiment 1, except that: HZSM-5 molecular sieve is selected as the support, and the active components are 5 wt.% cerium oxide, 5 wt.% chromium oxide, and 0.15 wt.% platinum (denoted as 5Ce5Cr / 0.15Pt). The specific preparation method includes the following steps:

[0106] S10. Using the impregnation method, according to the composite oxide loading, the corresponding mass of cerium nitrate and chromium nitrate are dissolved in deionized water, HZSM-5 molecular sieve powder is added and mixed and stirred for 4 hours. After the mixture is evaporated and dried at 80°C, it is calcined at 500°C in air atmosphere for 3 hours to obtain the intermediate with the active component of the composite oxide loaded on HZSM-5 molecular sieve.

[0107] S20. Using electrostatic adsorption, the appropriate mass of chloropalladium acid is dissolved in deionized water according to the noble metal loading. Dilute hydrochloric acid is added dropwise to adjust the pH of the solution to 4.0. Intermediate powder is added and mixed and stirred. After filtration and washing, the solution is dried at 110°C and then calcined at 550°C in air for 3 hours to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

[0108] The catalyst prepared in this embodiment was used for a catalytic combustion reaction, and its performance was tested. The chlorine-containing volatile organic compound tested was chlorobenzene with a concentration of 500 ppm and a space velocity of 5000 h⁻¹. -1 The T90 temperature is 238℃, and the reaction stability time is 120h at 300℃.

[0109] Example 5

[0110] The basic content of this embodiment is the same as that of Embodiment 1, except that: HZSM-5 molecular sieve is selected as the support, and the active components are 7.5 wt.% cerium oxide, 7.5 wt.% cobalt oxide, and 0.05 wt.% platinum (denoted as 7.5Ce7.5Co / 0.05Pt). The specific preparation method includes the following steps:

[0111] S10. Using the impregnation method, according to the loading of the composite oxide, the corresponding mass of cerium nitrate and cobalt nitrate are dissolved in deionized water, HZSM-5 molecular sieve powder is added and mixed and stirred for 4 hours. After the mixture is evaporated and dried at 80°C, it is calcined at 500°C in air atmosphere for 3 hours to obtain the intermediate with the active component of the composite oxide loaded on HZSM-5 molecular sieve.

[0112] S20. Using electrostatic adsorption, dissolve the corresponding mass of chloropalladium acid in deionized water according to the noble metal loading, add dilute hydrochloric acid to adjust the pH of the solution to 3.5, add the intermediate powder obtained in step S10 and mix and stir, filter and wash, dry at 110°C, and calcine at 550°C in air atmosphere for 3 hours to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

[0113] The catalyst prepared in this embodiment was used for a catalytic combustion reaction, and its performance was tested. The tested chlorine-containing volatile organic compound, trichloroethylene, had a concentration of 1000 ppm and a space velocity of 20000 h⁻¹. -1The T90 temperature is 245℃, and the reaction stability time is 120h at 300℃.

[0114] The test results of Examples 2-5 show that the catalyst can achieve a removal rate of over 90% for different types of chlorinated volatile organic compounds, such as dichloromethane, dichloroethane, chlorobenzene, and trichloroethylene, at temperatures below 250°C. Furthermore, it remains stable during the reaction at 300°C for 120 hours, maintaining a removal efficiency of over 90% of the initial conversion rate. This indicates that the catalyst of the present invention has good catalytic activity and stability when applied to the catalytic combustion treatment of chlorinated organic waste gas.

[0115] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the data used is only one embodiment of the present invention. The actual combination of data is not limited to this. Therefore, if those skilled in the art are inspired by this description and, without departing from the spirit of the present invention, devise similar embodiments and examples of the technical solution without creative design, all such embodiments and examples should fall within the protection scope of the present invention.

Claims

1. The application of a catalyst in the catalytic combustion of chlorine-containing organic waste gas, characterized in that: The catalyst is brought into contact with chlorinated organic waste gas to undergo a catalytic reaction, generating carbon dioxide, water, hydrogen chloride and chlorine gas, wherein the concentration of chlorinated organic matter in the chlorinated organic waste gas is 100~2000 ppm; The catalyst comprises a support and an active component. The active component includes an oxide active component and a noble metal active component. The oxide active component is loaded onto the support by an impregnation method, and the noble metal active component is loaded onto the oxide active component by an electrostatic adsorption method. The support is HZSM-5 molecular sieve, the loading of the oxide active component is 10% to 25% of the support mass, and the oxide active component includes cerium oxide and an auxiliary metal oxide, with a mass ratio of cerium oxide to auxiliary metal oxide of 1:

1. The auxiliary metal is one or more of Cu, Cr, and Co, and the noble metal active component is one or two of Pt and Pd.

2. The application according to claim 1, characterized in that: The catalytic reaction is carried out at a temperature of 200℃~300℃, and the volume hourly space velocity (VHSV) of the chlorinated organic waste gas is 500~30000 h⁻¹. -1 .

3. The application according to claim 1, characterized in that: The loading of the noble metal active component is 0.01% to 0.2% of the carrier mass.

4. The application according to claim 1, characterized in that: The method for preparing the catalyst includes the following steps: S10. Using the impregnation method, a certain amount of oxide active component precursor is dissolved in water to obtain a solution containing oxide active component precursor. HZSM-5 molecular sieve powder is added to the solution and mixed and stirred for 4 hours. After evaporation and drying at 80℃~120℃, the solution is calcined at 400℃~600℃ in air atmosphere for 3 hours to obtain an intermediate with oxide active component loaded on HZSM-5 molecular sieve. S20. Using electrostatic adsorption, a certain amount of noble metal active component precursor is dissolved in water to obtain a solution containing the noble metal active component precursor. An intermediate is added to the solution, the pH is adjusted to 3-5 and the mixture is stirred to allow the noble metal active component to be adsorbed on the surface of the oxide active component. The solution is filtered and washed, dried at 80℃-120℃, and then calcined at 400℃-600℃ for 3 hours in an air atmosphere to obtain a catalyst for the catalytic combustion of chlorinated organic compounds.

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