A perovskite-based catalyst with bifunctional sites, a method of making and use thereof in catalyzing chlorinated volatile organic pollutants

Abstract

The application discloses a perovskite-based catalyst with a bifunctional site, a preparation method and application of the catalyst in catalyzing chlorinated volatile organic pollutants, and relates to the technical field of catalysts. The preparation method comprises the following steps: adding citric acid and a modifier into a solution containing a lanthanum salt and a cobalt salt, and generating a gel under heating; aging and calcining the gel to obtain a powder; dispersing the powder in a nitric acid solution, separating, drying to obtain a dried powder, and then dispersing the dried powder into a phosphoric acid solution, separating, and drying to obtain the perovskite-based catalyst with the bifunctional site. The material preparation method is simple, economical and easy to operate, can effectively degrade CVOCs under low-temperature conditions by utilizing the synergistic effect between surface acidic sites and active sites, reduces the energy consumption of the reaction process, promotes the desorption of toxic species adsorbed on the surface of the material in the reaction process, inhibits the generation of toxic by-products, realizes the catalytic concept of economy and environmental protection, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of air pollution control technology, and relates to a perovskite-based catalyst with dual functional sites, its preparation method, and its application in catalyzing chlorine-containing volatile organic pollutants. Background Technology

[0002] Volatile organic compounds (VOCs) are fine particulate matter in the atmosphere (PM2.5). 2.5 It is an important precursor to both oxygen and ozone (O3), and its efficient control is an important issue in the field of air pollution control in my country at present.

[0003] VOCs generally refer to organic liquids and solids with a saturated vapor pressure greater than 70 Pa at room temperature and a boiling point below 260℃ at normal pressure. These compounds are widely used in industrial fields such as packaging printing, automotive painting, synthetic leather, and rubber recycling. Their main environmental sources are incomplete combustion of fuels and waste, organic emissions from chemical preparation processes (oil refining, petrochemicals, coatings, inks, adhesives, pesticides, and pharmaceuticals), and volatile emissions from solvent use (printing and packaging, automotive painting, furniture manufacturing, footwear and apparel manufacturing, and grain fumigation, etc.). They mainly include alkanes, aromatics, alkenes, halogenated hydrocarbons, esters, aldehydes, ketones, and others. Besides some general VOC pollution characteristics, chlorinated volatile organic compounds (CVOCs) mostly possess stable physicochemical properties. Therefore, the pollution from these substances, due to their high persistence, high mobility, and high toxicity, has become a key focus and challenge in research.

[0004] Currently, commonly used industrial CVOCs treatment methods can be divided into two main categories: non-destructive (physical adsorption, condensation, membrane separation, etc.) and destructive technologies (direct combustion, catalytic combustion, biodegradation, etc.). Among various CVOCs treatment technologies, low-temperature catalytic combustion is considered an economical and reliable method due to its advantages such as low ignition temperature, high reactivity, and controllable selectivity. Its core lies in catalyst design. Traditional noble metal-based catalysts are widely used for catalytic destruction of CVOCs and exhibit excellent catalytic activity. However, due to the presence of chloride (Cl), noble metal-based catalysts often encounter problems such as the formation of toxic chlorine byproducts and catalyst deactivation due to chloride poisoning, coking, and water competitive adsorption, making them unsuitable for sustained operation in industrial applications.

[0005] Perovskite-based catalysts are well-suited for thermal catalysis under real-world conditions (water vapor, thermal shock, chlorine poisoning) due to their excellent structural and thermal stability. However, pure perovskite-based catalysts exhibit less than ideal performance in the catalytic destruction of CVOCs due to their small specific surface area and poor redox capabilities (high complete destruction temperature and poor chlorine resistance). Therefore, developing a highly efficient and reliable industrial catalyst for the catalytic destruction of CVOCs has become a critical issue that urgently needs to be addressed. Summary of the Invention

[0006] To overcome the problems of insufficient low-temperature activity, poor resistance to poisoning, and generation of toxic byproducts in existing perovskite-based catalysts, the present invention aims to provide a perovskite-based catalyst with dual functional sites, a preparation method thereof, and its application in catalyzing chlorine-containing volatile organic pollutants. The perovskite-based catalyst with dual functional sites prepared by this method exhibits good low-temperature activity, chlorine resistance, and product selectivity, thereby achieving high catalytic efficiency, strong resistance to poisoning, and low byproduct yield while also realizing its environmentally friendly characteristics.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a perovskite-based catalyst with dual functional sites includes the following steps:

[0009] Citric acid and a modifier are added to a solution containing lanthanum and cobalt salts, and a gel is formed upon heating.

[0010] The gel was aged and then calcined to obtain a powder;

[0011] The powder was dispersed in a nitric acid solution, separated, and dried to obtain the dried powder. The dried powder was then dispersed in a phosphoric acid solution, separated, and dried to obtain a perovskite-based catalyst with bifunctional sites.

[0012] Furthermore, the lanthanum salt is lanthanum nitrate, and the cobalt salt is cobalt nitrate.

[0013] Furthermore, the mass ratio of lanthanum salt to cobalt salt is 4.3-10.8:2.9-7.3.

[0014] Furthermore, the mass ratio of citric acid to cobalt salt is 4.2-10.5:2.9-7.3.

[0015] Furthermore, the modifier is ethylene glycol, and the mass ratio of the modifier to the cobalt salt is 0.8-2.1:2.9-7.3.

[0016] Furthermore, the aging process is as follows: aging at 120-130℃ for 12-15 hours; the calcination process is as follows: first calcining at 350-400℃ for 3-4 hours, and then calcining at 750-850℃ for 3-4 hours.

[0017] Furthermore, the nitric acid solution concentration was 1 mol / L, and the dispersion time was 30 minutes; the phosphoric acid solution concentration was 0.1 mol / L, and the dispersion time was 40-50 minutes.

[0018] A perovskite-based catalyst with dual functional sites.

[0019] Application of a perovskite-based catalyst with dual functional sites in the catalysis of chlorine-containing volatile organic pollutants.

[0020] Furthermore, in the reaction of m-dichlorobenzene, the space velocity is 20,000–30,000 mL·h. -1 ·g -1 Under conditions of oxygen concentration of 10-21%, the catalyst degrades m-dichlorobenzene at 150-450℃.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention employs a two-step acid treatment strategy. First, the perovskite material surface is reconstructed to expose sufficient active sites and activate lattice oxygen, optimizing its redox capabilities. Then, the material surface is modified with phosphoric acid to introduce abundant... Acidic sites are added to increase the acidity of the material surface, thereby activating the synergistic effect between active and acidic sites. Compared with traditional modification strategies for perovskite-based catalysts, the two-step acid treatment modification strategy balances the catalyst's redox capacity and surface acidity. It achieves efficient and stable destruction of CVOCs through the synergistic effect between active and acidic sites. Furthermore, this modification method is simple, convenient, and quick, saving time and energy.

[0023] The P-Co-LaCoO3 perovskite catalyst prepared in this invention exhibits excellent low-temperature reduction performance, superior chlorine resistance, water resistance, and thermal shock resistance in the degradation of m-dichlorobenzene. This is particularly evident at a m-dichlorobenzene concentration of 500 ppm and a space velocity of 20000 mL·h⁻¹. -1 ·g -1Under suitable conditions, a 90% conversion rate was achieved at 350℃, and the conversion rate remained around 80% after 30 hours of continuous reaction, indicating excellent catalytic activity and chlorine resistance. No deactivation was observed after 30 hours of reaction at 500℃, demonstrating strong resistance to thermal shock. Furthermore, the introduction of 5 vol.% water vapor increased the catalytic activity by 15%, and the yield of toxic byproducts was only 10% of that under dry conditions, indicating excellent water resistance. The presence of water vapor also promoted the conversion of m-dichlorobenzene and inhibited the formation of toxic byproducts. This catalyst possesses advantages such as low cost, good low-temperature activity, strong water resistance, good resistance to poisoning, and high selectivity for byproducts, making it a promising candidate for low-temperature purification of chlorine-containing volatile organic pollutants. Attached Figure Description

[0024] Figure 1 This is the temperature-programmed reduction (H2-TPR) curve of the perovskite-based catalyst with dual functional sites in this invention;

[0025] Figure 2 The temperature-programmed desorption (NH3-TPD) curve of the perovskite-based catalyst with dual functional sites in this invention is shown.

[0026] Figure 3 The XPS curves show the valence state distribution of O1s elements in the perovskite-based catalyst with dual functional sites in this invention.

[0027] Figure 4 The activity test curve of the perovskite-based catalyst with dual functional sites in this invention for catalytic degradation of m-dichlorobenzene is shown.

[0028] Figure 5 The stability test curve of the perovskite-based catalyst with dual functional sites in this invention for catalytic degradation of m-dichlorobenzene is shown.

[0029] Figure 6 The thermal shock resistance test curve of the perovskite-based catalyst with dual functional sites in this invention for catalytic degradation of m-dichlorobenzene;

[0030] Figure 7 The water resistance test curve of the perovskite-based catalyst with dual functional sites in this invention for catalytic degradation of m-dichlorobenzene;

[0031] Figure 8 This is the byproduct distribution curve during the water resistance test of the perovskite-based catalyst with dual functional sites in this invention for catalytic degradation of m-dichlorobenzene. Detailed Implementation

[0032] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0033] This invention utilizes the sol-gel method and acid treatment to prepare a multifunctional perovskite-based catalyst, P-Co-LaCoO3, for the synergistic treatment of chlorinated volatile organic compounds. The main approach involves a two-step acid treatment modification strategy to directionally anchor phosphate ions onto lanthanum sites on the surface. Combined with selective nitric acid etching, this increases the content of surface defects, activates the synergistic effect between active and acidic sites, and enhances its low-temperature oxidation activity and resistance to poisoning. This perovskite-based catalyst successfully generates different functional centers on the material surface through the two-step acid treatment modification strategy, making it an effective degradation material for chlorinated volatile organic pollutants. The specific steps are as follows:

[0034] (1) Dissolve 4.3-10.8g of lanthanum nitrate in 40-100mL of deionized water and stir at 600-800r / min for 40min at room temperature until it is completely dissolved and a clear and transparent solution is formed.

[0035] (2) Dissolve 2.9-7.3g of cobalt nitrate in the clear solution obtained in step (1), stir at 600-800r / min for 40min at room temperature until it is completely dissolved and a clear and transparent solution is formed, and heat to 90℃;

[0036] (3) Dissolve 4.2-10.5g of citric acid in the clear solution obtained after heating in step (2), stir at 600-800r / min at 90℃ for 60min until it is completely dissolved and a clear and transparent solution is formed, and then cool down to 80℃.

[0037] (4) Add 0.8-2.1g of ethylene glycol (modifier) ​​dropwise to the solution in step (3). After the addition is complete, stir at 600-800r / min at 80℃ for 8 hours to promote the solution to fully react and form a gel.

[0038] (5) Place the gel obtained in step (4) in an oven at 120-130℃ for 12-15 hours to age it and obtain the precursor;

[0039] (6) The precursor obtained in step (5) is calcined in a muffle furnace at 350-400℃ for 2-4 hours, and then calcined at 750-850℃ for 3-4 hours to obtain a black solid powder.

[0040] (7) Redisperse 2g of the black powder obtained in step (6) in 40mL of nitric acid solution with a concentration of 1mol / L, and stir at 600-800r / min for 30min at room temperature;

[0041] (8) The solution obtained in step (7) was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain black powder. The obtained black powder was then placed in a vacuum drying oven and dried at 60°C for 10 hours until the powder was dry.

[0042] (9) Redisperse 1g of the black powder obtained in step (8) in 60mL of 0.1mol / L phosphoric acid solution and sonicate for 40-50min.

[0043] (10) The solution from step (9) was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain a black powder. The black powder was then placed in a vacuum drying oven and dried at 60°C for 10 hours until the powder was dry, thus obtaining the catalyst.

[0044] The catalyst prepared by this invention is selectively etched with surface metal elements by nitric acid treatment, exposing more surface active sites and activating lattice oxygen on the catalyst surface. Therefore, the material has excellent low-temperature redox ability and abundant active sites.

[0045] The catalyst prepared in this invention is treated with phosphoric acid, which allows the phosphate ions to be directionally anchored at lanthanum sites, resulting in abundant acidic sites on the material surface.

[0046] The catalyst prepared in this invention activates the synergistic effect between active sites and acidic sites through a two-step acid treatment. Co3O4 exposed on the material surface primarily provides low-temperature reduction active sites and enables deep oxidation of the target pollutant, while La mainly provides phosphate anchoring sites and promotes the transfer and removal of chlorine. The synergistic effect between these two functional sites simultaneously promotes the deep oxidation of m-dichlorobenzene.

[0047] The application of the perovskite-based catalyst with dual functional sites prepared in this invention for catalyzing chlorine-containing volatile organic pollutants, specifically in the reaction space velocity of 20,000–30,000 mL·h. -1 ·g -1 Under conditions of oxygen concentration of 10-21%, 90% degradation of intermediate dichlorobenzene, a typical industrial CVOC, can be achieved at around 350℃.

[0048] Example 1: Preparation of a perovskite-based catalyst with dual functional sites using the sol-gel method and acid treatment.

[0049] 7.58 g of lanthanum nitrate and 5.09 g of cobalt nitrate were dissolved in 70 mL of deionized water and stirred at 600 rpm for 40 min at room temperature until completely dissolved and a clear, transparent solution was formed. The solution was then heated to 90 °C. 7.35 g of citric acid was added, and the mixture was stirred at 600 rpm for 60 min at 90 °C until completely dissolved and a clear, transparent solution was formed. The temperature was then lowered to 80 °C. 1.45 g of ethylene glycol was then added dropwise, and the mixture was stirred at 600 rpm for 8 h at 80 °C to promote a complete reaction and gel formation. The gel was aged in an oven at 120 °C for 12 h to obtain a precursor. The precursor was then calcined in a muffle furnace at 350 °C for 2 h, followed by calcination at 800 °C for 3 h to obtain a black solid powder. Subsequently, 2g of the black powder was redispersed in 40mL of 1mol / L nitric acid solution and stirred at 800r / min for 30min at room temperature. The resulting liquid was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain the black powder. The black powder was then dried in a vacuum drying oven at 60℃ for 10h until dry. 1g of the prepared dried powder was redispersed in 60mL of 0.1mol / L phosphoric acid solution and sonicated for 40min. The resulting liquid was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain the black powder. The black powder was then dried in a vacuum drying oven at 60℃ for 10h until dry, finally yielding a perovskite-based catalyst with dual functional sites, namely P-Co-LaCoO3 oxide.

[0050] See Figure 1 As can be seen from the figure, the perovskite-based catalyst with bifunctional sites exhibits a reducible peak at 283℃, indicating that the material has excellent low-temperature reducibility and has a significant advantage in the field of catalytic oxidation.

[0051] See Figure 2 As can be seen, the perovskite-based catalyst with dual functional sites exhibited an ammonia desorption peak at 201℃, indicating that the material has excellent weak acidity performance and a good inhibitory effect on polychlorinated byproducts during the catalytic oxidation of chlorine-containing volatile organic compounds.

[0052] See Figure 3 It can be seen that the surface of the perovskite-based catalyst with dual functional sites contains abundant surface-adsorbed oxygen (531.2 eV), which can promote the deep oxidation of chlorine-containing volatile organic pollutants.

[0053] The catalyst prepared in this invention has a large specific surface area (50.74 m²). 2 ·g -1 ) and pore volume (0.274cm) 3 ·g -1This can effectively promote the transport and transfer of target pollutants on the surface of the catalytic material;

[0054] Example 2: Activity testing and evaluation of perovskite-based catalysts with dual functional sites for the catalytic degradation of m-dichlorobenzene.

[0055] The solid powder obtained in Example 1 was compressed into tablets and sieved (40-60 mesh). 0.3 g of the sieved catalyst was accurately weighed. Using m-dichlorobenzene as a probe gas, the concentration of the reactants was controlled at 500 ppm, and the reaction space velocity was 20000 mL·h. -1 ·g -1 Furthermore, under the condition of 21% oxygen concentration, the catalytic activity of the catalyst was tested at different temperatures (150, 200, 250, 300, 350, 380, 400, 430 and 450℃), and the reaction products were monitored and analyzed by gas chromatography.

[0056] See Figure 4 It can be seen that the perovskite-based catalyst with dual functional sites exhibits good low-temperature catalytic performance, achieving good performance at 350℃ and a reaction space velocity of approximately 20,000 mL·h. -1 ·g -1 Under these conditions, a 90% conversion of m-dichlorobenzene can be achieved, which can be applied to current industrial RCO catalytic reaction devices and achieve good results.

[0057] Example 3: Stability and thermal shock resistance test of perovskite-based catalyst with dual functional sites for catalytic degradation of m-dichlorobenzene.

[0058] The solid powder obtained in Example 1 was compressed into tablets and sieved (40-60 mesh). 0.3 g of the sieved catalyst was accurately weighed and placed in the fixed bed of the evaluation device. m-Dichlorobenzene was used as the probe gas, the concentration of the reactants was controlled at 500 ppm, and the reaction space velocity was 20000 mL·h. -1 ·g -1 The oxygen concentration was 21%, and the catalytic activity of the catalyst was continuously tested at 350℃ and 500℃. The reaction products were monitored and analyzed by gas chromatography.

[0059] See Figure 5 It can be seen that the perovskite-based catalyst with bifunctional sites can achieve good results at 350℃ and a reaction space velocity of approximately 20,000 mL·h. -1 ·g -1 Under these conditions, the catalyst maintained a conversion rate of approximately 80% for m-dichlorobenzene within 30 hours, demonstrating excellent oxidative stability for chlorinated volatile organic compounds. See also... Figure 6 It can be seen that the perovskite-based catalyst with bifunctional sites can achieve good results at 500℃ and a reaction space velocity of approximately 20,000 mL·h. -1 ·g -1Under these conditions, the catalyst maintained a conversion rate of approximately 100% for m-dichlorobenzene within 30 hours, demonstrating excellent thermal shock resistance.

[0060] Example 4: Analysis of the intermediate product of m-dichlorobenzene catalytic degradation by a perovskite-based catalyst with dual functional sites.

[0061] The solid powder obtained in Example 1 was compressed into tablets and sieved (40-60 mesh). 0.3 g of the sieved catalyst was accurately weighed. Using m-dichlorobenzene as a probe gas, the concentration of the reactants was controlled at 500 ppm, and the reaction space velocity was 20000 mL·h. -1 ·g -1 With an oxygen concentration of 21%, the generation of intermediate products of the catalyst at different temperatures (150, 200, 250, 300, 350, 380, 400, 430 and 450 °C) was tested. The reaction products were monitored and analyzed by gas chromatography and in-situ online mass spectrometry.

[0062] Example 5: Water resistance test and intermediate product analysis of the catalytic degradation of m-dichlorobenzene by a perovskite-based catalyst with dual functional sites.

[0063] The solid powder obtained in Example 1 was compressed into tablets and sieved (40-60 mesh). 0.3 g of the sieved catalyst was accurately weighed and placed in the fixed bed of the evaluation device. m-Dichlorobenzene was used as the probe gas, the concentration of the reactants was controlled at 500 ppm, and water vapor of different concentrations (1, 2, and 5 vol.%) was introduced. The reaction space velocity was 20000 mL·h. -1 ·g -1 The oxygen concentration was 21%, and the catalytic activity of the catalyst was continuously tested at 350℃. The reaction products were monitored and analyzed by gas chromatography.

[0064] See Figure 7 It can be seen that the perovskite-based catalyst with bifunctional sites can achieve good results at 350℃ and a reaction space velocity of approximately 20,000 mL·h. -1 ·g -1 Under certain conditions, within 30 hours, different concentrations of water vapor could improve the conversion rate of m-dichlorobenzene by this catalyst. Specifically, introducing 5 vol.% water vapor increased the catalytic activity from 80% to 95%. This catalyst exhibits excellent water resistance.

[0065] See Figure 8 It can be seen that the perovskite-based catalyst with bifunctional sites can achieve good results at 350℃ and a reaction space velocity of approximately 20,000 mL·h. -1 ·g -1Under the given conditions, water vapor of different concentrations could significantly inhibit the formation of byproducts within 30 hours. When 5 vol.% water vapor was introduced, the amount of byproducts generated was only 10% of that under dry conditions, indicating that water vapor present in actual working conditions has a significant promoting effect on the catalytic degradation of m-dichlorobenzene by this catalyst.

[0066] Example 6

[0067] 4.3 g of lanthanum nitrate and 2.9 g of cobalt nitrate were dissolved in 80 mL of deionized water and stirred at 600 rpm for 40 min at room temperature until completely dissolved and a clear, transparent solution was formed. The solution was then heated to 90 °C. 4.2 g of citric acid was added, and the mixture was stirred at 800 rpm for 60 min at 90 °C until completely dissolved and a clear, transparent solution was formed. The temperature was then lowered to 80 °C. 0.8 g of ethylene glycol was then added dropwise, and the mixture was stirred at 800 rpm for 8 h at 80 °C to promote a complete reaction and gel formation. The gel was aged in an oven at 120 °C for 15 h to obtain a precursor. The precursor was then calcined in a muffle furnace at 350 °C for 4 h, followed by calcination at 770 °C for 3 h to obtain a black solid powder. Subsequently, 2g of the black powder was redispersed in 40mL of 1mol / L nitric acid solution and stirred at 600r / min for 30min at room temperature. The resulting liquid was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain the black powder. The black powder was then dried in a vacuum drying oven at 60℃ for 10h until dry. 1g of the prepared dried powder was redispersed in 60mL of 0.1mol / L phosphoric acid solution and sonicated for 40min. The resulting liquid was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain the black powder. The black powder was then dried in a vacuum drying oven at 60℃ for 10h until dry, thus obtaining a perovskite-based catalyst with dual functional sites.

[0068] Example 7

[0069] 10.8 g of lanthanum nitrate and 7.3 g of cobalt nitrate were dissolved in 100 mL of deionized water and stirred at 800 rpm for 40 min at room temperature until completely dissolved and a clear, transparent solution was formed. The solution was then heated to 90 °C. 10.5 g of citric acid was added, and the mixture was stirred at 600 rpm for 60 min at 90 °C until completely dissolved and a clear, transparent solution was formed. The temperature was then lowered to 80 °C. 2.1 g of ethylene glycol was then added dropwise, and the mixture was stirred at 600 rpm for 8 h at 80 °C to promote a complete reaction and gel formation. The gel was aged in an oven at 130 °C for 12 h to obtain a precursor. The precursor was then calcined in a muffle furnace at 400 °C for 2 h, followed by calcination at 750 °C for 4 h to obtain a black solid powder. Subsequently, 2g of the black powder was redispersed in 40mL of 1mol / L nitric acid solution and stirred at 800r / min for 30min at room temperature. The resulting liquid was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain the black powder. The black powder was then dried in a vacuum drying oven at 60℃ for 10h until dry. 1g of the prepared dried powder was redispersed in 60mL of 0.1mol / L phosphoric acid solution and sonicated for 50min. The resulting liquid was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain the black powder. The black powder was then dried in a vacuum drying oven at 60℃ for 10h until dry, thus obtaining a perovskite-based catalyst with dual functional sites.

[0070] Example 8

[0071] 6.5 g of lanthanum nitrate and 4.4 g of cobalt nitrate were dissolved in 60 mL of deionized water and stirred at 700 rpm for 40 min at room temperature until completely dissolved and a clear, transparent solution was formed. The solution was then heated to 90 °C. 6.3 g of citric acid was added, and the mixture was stirred at 700 rpm for 60 min at 90 °C until completely dissolved and a clear, transparent solution was formed. The temperature was then lowered to 80 °C. 1.2 g of ethylene glycol was then added dropwise, and the mixture was stirred at 700 rpm for 8 h at 80 °C to promote a complete reaction and gel formation. The gel was aged in an oven at 125 °C for 13 h to obtain a precursor. The precursor was then calcined in a muffle furnace at 370 °C for 3 h, followed by calcination at 850 °C for 3 h to obtain a black solid powder. Subsequently, 2g of the black powder was redispersed in 40mL of 1mol / L nitric acid solution and stirred at 700r / min for 30min at room temperature. The resulting liquid was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain the black powder. The black powder was then dried in a vacuum drying oven at 60℃ for 10h until dry. 1g of the prepared dried powder was redispersed in 60mL of 0.1mol / L phosphoric acid solution and sonicated for 45min. The resulting liquid was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain the black powder. The black powder was then dried in a vacuum drying oven at 60℃ for 10h until dry, thus obtaining a perovskite-based catalyst with dual functional sites.

[0072] Example 9

[0073] 9.7 g of lanthanum nitrate and 6.5 g of cobalt nitrate were dissolved in 100 mL of deionized water and stirred at 650 rpm for 40 min at room temperature until completely dissolved and a clear, transparent solution was formed. The solution was then heated to 90 °C. Next, 9.5 g of citric acid was added, and the mixture was stirred at 750 rpm for 60 min at 90 °C until completely dissolved and a clear, transparent solution was formed. The temperature was then lowered to 80 °C. Then, 1.9 g of ethylene glycol was added dropwise, and the mixture was stirred at 800 rpm for 8 h at 80 °C to promote a complete reaction and gel formation. The gel was aged in an oven at 125 °C for 14 h to obtain a precursor. The precursor was then calcined in a muffle furnace at 380 °C for 2 h, followed by calcination at 800 °C for 3 h to obtain a black solid powder. Subsequently, 2g of the black powder was redispersed in 40mL of 1mol / L nitric acid solution and stirred at 800r / min for 30min at room temperature. The resulting liquid was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain the black powder. The obtained black powder was then placed in a vacuum drying oven and dried at 60℃ for 10h until the powder was dry. 1g of the prepared dried powder was redispersed in 60mL of 0.1mol / L phosphoric acid solution and sonicated for 40min. The resulting liquid was then filtered under vacuum and washed repeatedly with deionized water and anhydrous ethanol to obtain the black powder. The obtained black powder was then placed in a vacuum drying oven and dried at 60℃ for 10h until the powder was dry, thus obtaining a perovskite-based catalyst with dual functional sites.

[0074] The perovskite-based catalyst with dual functional sites prepared in this invention is synthesized via a sol-gel method and modified using a two-step acid treatment strategy. Nitric acid treatment exposes sufficient active sites (Co) on the perovskite material surface, followed by phosphoric acid modification to anchor phosphate ions at lanthanum sites on the surface. The prepared catalyst, P-Co-LaCoO3, is then applied to the catalytic degradation of CVOCs. This invention offers a simple, economical, and easy-to-operate method for material preparation. It effectively degrades CVOCs at low temperatures by utilizing the synergistic effect between surface acidic sites and active sites, reducing energy consumption in the reaction process. Furthermore, it promotes the desorption of toxic species adsorbed on the material surface during the reaction and inhibits the formation of toxic byproducts, achieving an economical and environmentally friendly catalytic approach with promising industrial application prospects.

[0075] The above description is only of the preferred embodiment of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All variations made within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

[0076] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. The application of a perovskite-based catalyst with dual functional sites in the catalysis of chlorine-containing volatile organic pollutants, characterized in that, The preparation method of the perovskite-based catalyst with dual functional sites includes the following steps: Citric acid and a modifier are added to a solution containing lanthanum salt and cobalt salt, and a gel is formed upon heating; wherein the modifier is ethylene glycol. The gel is aged and then calcined to obtain powder; the calcination process is as follows: first calcined at 350-400℃ for 3-4 h, and then calcined at 750-850℃ for 3-4 h. The powder was dispersed in a nitric acid solution, separated, and dried to obtain the dried powder. The dried powder was then dispersed in a phosphoric acid solution, separated, and dried to obtain a perovskite-based catalyst with bifunctional sites.

2. The application according to claim 1, characterized in that, Lanthanum salt is lanthanum nitrate, and cobalt salt is cobalt nitrate.

3. The application according to claim 2, characterized in that, The mass ratio of lanthanum salt to cobalt salt is 4.3-10.8:2.9-7.

3.

4. The application according to claim 1, characterized in that, The mass ratio of citric acid to cobalt salt is 4.2-10.5:2.9-7.

3.

5. The application according to claim 1, characterized in that, The mass ratio of modifier to cobalt salt is 0.8-2.1:2.9-7.

3.

6. The application according to claim 1, characterized in that, The aging process is as follows: aging at 120-130℃ for 12-15 hours.

7. The application according to claim 1, characterized in that, When the nitric acid solution has a concentration of 1 mol / L, the dispersion time for dispersing the powder in the nitric acid solution is 30 minutes; when the phosphoric acid solution has a concentration of 0.1 mol / L, the dispersion time for dispersing the dried powder in the phosphoric acid solution is 40-50 minutes.

8. The application according to claim 1, characterized in that, The chlorine-containing volatile organic pollutant is m-dichlorobenzene; the reaction space velocity of m-dichlorobenzene is 20000~30000 mL·h. -1 ·g -1 Under conditions of oxygen concentration of 10-21%, the catalyst degrades m-dichlorobenzene at 150-450℃.

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