Cerium-based VOCs purification catalyst, preparation method and application thereof
By preparing porous cerium-based organic framework materials with high specific surface area, the cost and stability issues of noble metal catalysts have been solved, achieving a highly efficient VOCs purification effect, which is suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF RESOURCES & ENVIRONMENT BEIJING ACAD OF SCI & TECH
- Filing Date
- 2023-10-19
- Publication Date
- 2026-05-29
Smart Images
Figure CN117654476B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of volatile organic compound (VOC) treatment technology, specifically relating to a cerium-based VOCs purification catalyst and its preparation method, and further relating to the application of a cerium-based VOCs purification catalyst. Background Technology
[0002] Volatile organic compounds (VOCs) are organic compounds with melting points below room temperature and boiling points between 50 and 260°C. Their main components are hydrocarbons, nitrogen- and sulfur-containing hydrocarbons, oxygenated hydrocarbons, halogenated hydrocarbons, alcohols, aldehydes, ketones, esters, and organic acids. They are a class of organic pollutants that are ubiquitous both indoors and outdoors and have complex compositions. VOCs can cause acid rain, photochemical smog, ozone depletion, the greenhouse effect, and even harm human health. Therefore, from the perspective of environmental protection and human health, VOCs control is essential. Among control methods, catalytic combustion technology has become the mainstream technology for VOCs control due to its advantages such as low ignition temperature, low energy consumption, and no secondary pollution. The key to this technology is the preparation and development of catalysts.
[0003] Currently used precious metal catalysts suffer from drawbacks such as high cost, high sintering risk, and susceptibility to poisoning, limiting their widespread application. Therefore, it is necessary to improve catalysts for VOCs removal. Summary of the Invention
[0004] This invention is based on the inventors' discoveries and understanding of the following facts and problems: Cerium dioxide (CeO2) possesses excellent redox properties, oxygen storage capacity (OSC), and various modification possibilities, effectively overcoming the problems of high cost, high sintering risk, and susceptibility to poisoning associated with precious metal catalysts, thus achieving high catalytic activity. From a synthetic perspective, traditional catalyst preparation methods, such as precipitation methods, while simple, often produce solid catalysts lacking porosity, which hinders the effective diffusion of reactants to active sites. Therefore, improvements are needed in catalyst preparation to enhance catalyst activity.
[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a method for preparing a cerium-based VOCs purification catalyst. The synthesis materials used in this method are relatively inexpensive, produce no secondary pollution, the process is simple, and it is easy to scale up for production. Furthermore, the catalyst prepared using porous organic framework materials with high specific surface area as precursors forms a mesoporous structure through the stacking of nanoparticles, which facilitates mass transfer during the reaction process, resulting in high catalytic activity and stability.
[0006] A method for preparing a cerium-based VOCs purification catalyst according to an embodiment of the present invention includes the following steps;
[0007] (1) Disperse the organic ligand and the cerium precursor in N,N-dimethylformamide to obtain an organic ligand solution and a cerium solution, respectively.
[0008] (2) The organic ligand solution obtained in step (1) is added to the cerium solution to carry out a hydrothermal reaction, and a solid product is obtained after solid-liquid separation;
[0009] (3) The solid product obtained in step (2) is washed, dried and calcined to obtain catalyst particles.
[0010] The advantages and technical effects of the preparation method of the cerium-based VOCs purification catalyst in this invention are as follows: 1. In the preparation method of this invention, N,N-dimethylformamide is used to disperse the organic ligand and the cerium precursor. N,N-dimethylformamide can highly disperse and fully contact the organic ligand and the cerium precursor, providing conditions for the formation of a cerium-based organic framework with a high specific surface area; 2. In the preparation method of this invention, the organic ligand and the cerium precursor solution are subjected to a hydrothermal reaction to prepare a porous cerium-based organic framework with a high specific surface area. The catalyst is then prepared using this porous organic framework material as a precursor. In the prepared catalyst, the active component CeO2 nanoparticles are stacked into a mesoporous structure, which is beneficial... 3. The mass transfer effect during the reaction process allows the crystal surface to be utilized to the maximum extent during catalysis; 4. The preparation method of the present invention produces a catalyst with high activity and stability, and effectively reduces the catalyst's activity temperature; 5. The method of the present invention can be used for the removal of volatile organic pollutants. It not only has high catalytic activity for the catalytic combustion of benzene pollutants, but also has a good removal effect for the catalytic combustion of aliphatic hydrocarbons. It can meet the treatment needs of various volatile organic pollutants and has good universality; 6. The preparation method of the present invention is simple, uses inexpensive synthetic materials, and does not generate secondary pollution, making it suitable for industrial production and application.
[0011] In some embodiments, the organic ligand includes at least one of 2-methylimidazole, terephthalic acid, trans-butenedioic acid, and trimesic acid.
[0012] In some embodiments, in step (1), the organic ligand includes at least two of 2-methylimidazole, terephthalic acid, fumaric acid, and trimellitic acid; preferably, the organic ligand is composed of two of 2-methylimidazole, terephthalic acid, fumaric acid, and trimellitic acid; more preferably, the molar ratio of the two organic ligands is 10:1 to 1:10.
[0013] In some embodiments, the organic ligand is composed of 2-methylimidazole and pyromellitic acid.
[0014] In some embodiments, in step (1), the concentration of the organic ligand solution is 0.1–2 mmol / mL, and the concentration of the cerium solution is 0.01–0.2 mmol / mL.
[0015] In some embodiments, in step (1), the cerium precursor comprises at least one of Ce(NH4)2(NO3)6 and Ce(NO3)3·6H2O.
[0016] In some embodiments, in step (2), the molar ratio of the organic ligand in the organic ligand solution to the cerium element in the cerium solution is 1:1 to 12:1; and / or, the reaction temperature of the hydrothermal reaction is 100 to 150°C, and the reaction time is 10 to 24 h.
[0017] This invention also provides a cerium-based VOCs purification catalyst, which is prepared using the preparation method of the cerium-based VOCs purification catalyst of this invention.
[0018] The advantages and technical effects of the cerium-based VOCs purification catalyst in this invention are as follows: 1. The catalyst in this invention has high activity and stability, low reaction activation temperature, and mild reaction conditions; 2. The catalyst in this invention has certain universality, not only having high catalytic activity for benzene-based substances, but also having good catalytic activity for aliphatic hydrocarbons.
[0019] This invention also provides an application of a cerium-based VOCs purification catalyst in the catalytic removal of VOCs gas.
[0020] The advantages and technical effects of the cerium-based VOCs purification catalyst in the catalytic removal of VOCs gas according to the embodiments of the present invention are as follows: 1. In the embodiments of the present invention, each gram of catalyst can process VOCs containing 1000-10000 mg / m³ per hour. 3 The amount of VOC waste gas is 10-120L, which can meet the application requirements; 2. In the embodiments of the present invention, the catalyst has a certain degree of universality and can improve the treatment efficiency of VOC waste gas.
[0021] In some embodiments, the VOCs gas includes at least one selected from benzene, halogenated hydrocarbons, esters, and acids; and / or, the temperature of the catalytic reaction is... 200-320℃ . Attached Figure Description
[0022] Figure 1 The graphs show the toluene catalytic combustion activity curves of the catalysts prepared in Examples 1-5.
[0023] Figure 2 The graphs show the toluene catalytic combustion activity curves of the catalysts prepared in Example 3 and Comparative Examples 1-3.
[0024] Figure 3 The following are the catalytic combustion activity curves of the catalysts prepared in Examples 1-3 for ethyl acetate.
[0025] Figure 4 The graph shows the stability of the toluene catalyst during combustion in Example 3.
[0026] Figure 5 The images show powder X-ray diffraction patterns of the catalysts prepared in Examples 1-5. Detailed Implementation
[0027] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0028] A method for preparing a cerium-based VOCs purification catalyst according to an embodiment of the present invention includes the following steps;
[0029] (1) Disperse the organic ligand and the cerium precursor in N,N-dimethylformamide to obtain an organic ligand solution and a cerium solution, respectively.
[0030] (2) The organic ligand solution obtained in step (1) is added to the cerium solution to carry out a hydrothermal reaction, and a solid product is obtained after solid-liquid separation;
[0031] (3) The solid product obtained in step (2) is washed, dried and calcined to obtain catalyst particles.
[0032] The preparation method of the cerium-based VOCs purification catalyst in this embodiment of the invention uses N,N-dimethylformamide to disperse organic ligands and cerium precursors. N,N-dimethylformamide enables the organic ligands and cerium precursors to be highly dispersed and fully contacted, providing conditions for the formation of a cerium-based organic framework with a high specific surface area. The preparation method of this embodiment of the invention involves a hydrothermal reaction of the organic ligand and cerium precursor solution to prepare a porous cerium-based organic framework with a high specific surface area. The catalyst is then prepared using this porous organic framework material as a precursor. In the prepared catalyst, the active component CeO2 nanoparticles are stacked into a mesoporous structure, which is beneficial for mass transfer during the reaction process. The method of this invention maximizes the utilization of the crystal surface during the catalytic process. The catalyst prepared by the method of this embodiment has high activity and stability, and effectively reduces the catalyst's activity temperature. The method of this embodiment can be used for the removal of volatile organic pollutants. It not only has high catalytic activity for the catalytic combustion of benzene pollutants, but also has a good removal effect on the catalytic combustion of aliphatic hydrocarbons. It can meet the treatment needs of various volatile organic pollutants and has good versatility. The preparation method of this embodiment is simple, uses inexpensive synthetic materials, and does not generate secondary pollution, making it suitable for widespread application in industrial production.
[0033] In some embodiments, in step (1), the organic ligand includes at least one of 2-methylimidazole, terephthalic acid, fumaric acid, and trimellitic acid; preferably, the organic ligand includes at least two of 2-methylimidazole, terephthalic acid, fumaric acid, and trimellitic acid; more preferably, the organic ligand is composed of two of 2-methylimidazole, terephthalic acid, fumaric acid, and trimellitic acid; more preferably, the molar ratio of the two ligands is 10:1 to 1:10. Most preferably, the organic ligand is composed of 2-methylimidazole and trimellitic acid or 2-methylimidazole and terephthalic acid; preferably, the molar ratio of 2-methylimidazole to trimellitic acid is 8-10:1, more preferably 10:1; the molar ratio of 2-methylimidazole to terephthalic acid is 8-10:1, more preferably 10:1.
[0034] In this embodiment of the invention, the types of organic ligands are preferred. In particular, when a mixed organic ligand is formed by combining two or more organic ligands, the binding mode and binding sequence with the central metal atom can be changed, thereby changing the microstructure of the prepared MOFs and thus affecting the catalytic effect.
[0035] In some embodiments, preferably, in step (1), the concentration of the organic ligand solution is 0.1–2 mmol / mL, and the concentration of the cerium solution is 0.01–0.2 mmol / mL. More preferably, the concentration of the organic ligand solution is 0.15–1.5 mmol / mL, and the concentration of the cerium solution is 0.1–0.2 mmol / mL.
[0036] In this embodiment of the invention, the concentrations of the ligand solution and the cerium solution are preferred. A suitable concentration is beneficial for the uniform dispersion of the organic ligand and the cerium precursor in the solvent, thereby ensuring the stability of the prepared catalyst.
[0037] In some embodiments, preferably, in step (1), the cerium precursor comprises at least one of Ce(NH4)2(NO3)6 and Ce(NO3)3·6H2O.
[0038] In some embodiments, preferably, in step (2), the molar ratio of the organic ligand in the ligand solution to the cerium element in the cerium solution is 1:1 to 12:1, preferably 8:1 to 12:1, and more preferably 10:1 to 12:1.
[0039] In this embodiment of the invention, the ratio of organic ligands to cerium is specified. A suitable ratio ensures that the prepared catalyst not only has good catalytic activity but also good stability. If too much cerium is added, Ce clusters will appear in the pores of the formed organic framework; if too little cerium is added, excess organic ligands will appear in the pores of the formed organic framework. Both of these situations are detrimental to the formation of the organic framework structure and thus hinder the improvement of catalyst yield and catalytic performance.
[0040] In some embodiments, preferably, in step (2), the hydrothermal reaction temperature is 100-150°C and the reaction time is 10-24h.
[0041] In this embodiment of the invention, a hydrothermal method was used to prepare cerium-containing organic framework materials, and the reaction conditions were optimized, which is beneficial to effectively control the particle size and morphology of the product, and the product has good dispersibility and stability.
[0042] In some embodiments, preferably, in step (3), the washing is performed by washing with ethanol and water three times each; the drying is performed by placing the product in a vacuum environment at 100-120°C for 12-24 hours; and the calcination is performed in an air atmosphere at 300-500°C for 2-6 hours.
[0043] In this embodiment of the invention, washing, drying and calcination can reduce the impurity content in the product and improve the catalytic effect of the catalyst.
[0044] This invention also provides a cerium-based VOCs purification catalyst, which is prepared using the preparation method of the cerium-based VOCs purification catalyst of this invention.
[0045] The cerium-based VOCs purification catalyst of this invention has high activity and stability, low reaction activation temperature, and mild reaction conditions. The catalyst has certain versatility, exhibiting high catalytic activity not only for benzene-based substances but also for aliphatic hydrocarbons.
[0046] This invention also provides an application of a cerium-based VOCs purification catalyst in the catalytic removal of VOCs gas.
[0047] The application of the cerium-based VOCs purification catalyst in the catalytic removal of VOCs gas according to embodiments of the present invention shows that each gram of catalyst can treat VOCs containing 1000-10000 mg / m³ per hour. 3 The catalyst can process 10-120L of VOC waste gas, which can meet the application requirements; the catalyst has a certain degree of versatility and can improve the treatment efficiency of VOC waste gas.
[0048] In some embodiments, preferably, the catalytic removal of VOCs gas involves a combustion reaction using air as an oxidant, causing the VOCs to catalytically combust, and the reaction temperature is 100–700°C. More preferably, the reactant temperature is 200–320°C.
[0049] In this embodiment of the invention, the use of this catalyst to treat VOCs waste gas can activate the catalyst at a lower temperature, reduce the reaction temperature of VOCs waste gas combustion, reduce energy consumption, ensure the catalytic activity of the catalyst, and improve the efficiency of VOCs waste gas treatment.
[0050] In some embodiments, preferably, the VOCs gas includes at least one of benzene, halogenated hydrocarbons, esters, and acids.
[0051] The technical solution of this application will be described below with reference to specific embodiments and accompanying drawings.
[0052] Example 1
[0053] (1) Dissolve 4.5 mmol of pyromellitic acid in 30 mL of N,N-dimethylformamide and stir until completely dissolved to obtain an organic ligand solution; dissolve 4.5 mmol of Ce(NO3)3·6H2O in 30 mL of N,N-dimethylformamide and stir until completely dissolved to obtain a cerium solution;
[0054] (2) The organic ligand solution was added dropwise to the cerium solution and stirred until homogeneous to obtain the Ce-based MOF precursor solution;
[0055] (3) The Ce-based MOF precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 120°C for 20 h. The mixture was then centrifuged to obtain a solid.
[0056] (4) The filtered solid product was washed three times with ethanol and three times with deionized water. The solid precipitate was dried at 120°C for 12 hours. After being removed, it was calcined at 400°C in air for 4 hours. Then it was pressed into tablets at 10 MPa, crushed, and sieved to obtain catalyst particles with a particle size of 40-60 mesh.
[0057] Example 2
[0058] (1) Dissolve 45 mmol of 2-methylimidazole in 30 mL of N,N-dimethylformamide and stir until completely dissolved to obtain an organic ligand solution; dissolve 4.5 mmol of Ce(NO3)3·6H2O in 30 mL of N,N-dimethylformamide and stir until completely dissolved to obtain a cerium solution;
[0059] (2) The organic ligand solution was added dropwise to the cerium solution and stirred until homogeneous to obtain the Ce-based MOF precursor solution;
[0060] (3) The Ce-based MOF precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 120°C for 20 h. The mixture was then centrifuged to obtain a solid.
[0061] (4) The filtered solid product was washed three times with ethanol and three times with deionized water. The solid precipitate was dried at 120°C for 12 hours. After being removed, it was calcined at 400°C in air for 4 hours. Then it was pressed into tablets at 10 MPa, crushed, and sieved to obtain catalyst particles with a particle size of 40-60 mesh.
[0062] Example 3
[0063] (1) Dissolve 30 mmol of 2-methylimidazole in 20 mL of N,N-dimethylformamide and stir until completely dissolved to obtain the first ligand solution; dissolve 3 mmol of trimesic acid in 20 mL of N,N-dimethylformamide and stir until completely dissolved to obtain the second ligand solution; dissolve 3 mmol of Ce(NO3)3·6H2O in 20 mL of N,N-dimethylformamide and stir until completely dissolved to obtain the cerium solution.
[0064] (2) Mix the first ligand solution and the second ligand solution and stir until homogeneous to obtain a mixed organic ligand solution; add the mixed organic ligand solution dropwise to the cerium solution and stir until homogeneous to obtain a Ce-based MOF precursor solution;
[0065] (3) The Ce-based MOF precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 120°C for 20 h. The mixture was then centrifuged to obtain a solid.
[0066] (4) The filtered solid product was washed three times with ethanol and three times with deionized water. The solid precipitate was dried at 100°C for 12 hours. After being removed, it was calcined at 400°C in air for 4 hours. Then it was pressed into tablets at 10 MPa, crushed, and sieved to obtain catalyst particles with a particle size of 40-60 mesh.
[0067] Example 4
[0068] (1) Dissolve 30 mmol of 2-methylimidazole in 20 mL of N,N-dimethylformamide and stir until completely dissolved to obtain the first ligand solution; dissolve 3 mmol of terephthalic acid in 20 mL of N,N-dimethylformamide and stir until completely dissolved to obtain the second ligand solution; dissolve 3 mmol of Ce(NO3)3·6H2O in 20 mL of N,N-dimethylformamide and stir until completely dissolved to obtain the cerium solution.
[0069] (2) Mix the first ligand solution and the second ligand solution and stir until homogeneous to obtain a mixed organic ligand solution; add the mixed organic ligand solution dropwise to the cerium solution and stir until homogeneous to obtain a Ce-based MOF precursor solution;
[0070] (3) The Ce-based MOF precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 120°C for 20 h. The mixture was then centrifuged to obtain a solid.
[0071] (4) The filtered solid product was washed three times with ethanol and three times with deionized water. The solid precipitate was dried at 120°C for 12 hours. After being removed, it was calcined at 400°C in air for 4 hours. Then it was pressed into tablets at 10 MPa, crushed, and sieved to obtain catalyst particles with a particle size of 40-60 mesh.
[0072] Example 5
[0073] (1) Dissolve 30 mmol of 2-methylimidazole in 20 mL of N,N-dimethylformamide and stir until completely dissolved to obtain the first ligand solution; dissolve 3 mmol of fumaric acid in 20 mL of N,N-dimethylformamide and stir until completely dissolved to obtain the second ligand solution; dissolve 3 mmol of Ce(NO3)3·6H2O in 20 mL of N,N-dimethylformamide and stir until completely dissolved to obtain the cerium solution.
[0074] (2) Mix the first ligand solution and the second ligand solution and stir until homogeneous to obtain a mixed organic ligand solution; add the mixed organic ligand solution dropwise to the cerium solution and stir until homogeneous to obtain a Ce-based MOF precursor solution;
[0075] (3) The Ce-based MOF precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 120°C for 20 h. The mixture was then centrifuged to obtain a solid.
[0076] (4) The filtered solid product was washed three times with ethanol and three times with deionized water. The solid precipitate was dried at 120°C for 12 hours. After being removed, it was calcined at 400°C in air for 4 hours. Then it was pressed into tablets at 10 MPa, crushed, and sieved to obtain catalyst particles with a particle size of 40-60 mesh.
[0077] Comparative Example 1
[0078] Weigh out 4.34 g of Ce(NO3)3·6H2O and 1 g of agar, and dissolve them in 100 mL of deionized water. Heat the mixed solution to 80 °C, magnetically stir until transparent, and allow it to cool naturally to room temperature for at least 72 hours. Calcine the synthesized gel at 400 °C in an air furnace for 4 hours, compress it into tablets at 10 MPa, pulverize it, and sieve it to obtain catalyst particles with a particle size of 40-60 mesh.
[0079] Comparative Example 2
[0080] Weigh 10g of Ce(NO3)3·6H2O and calcine it in an air atmosphere at 400℃ in a muffle furnace for 4 hours to obtain solid powder. Press the powder into tablets at 10MPa, crush it, and sieve it to obtain catalyst particles with a particle size of 40-60 mesh.
[0081] Comparative Example 3
[0082] The method is the same as in Example 1, except that in step (1), pyromellitic acid is dissolved in a mixed solution of ethanol and water with a volume ratio of 1:1, and Ce(NO3)3·6H2O is dissolved in deionized water.
[0083] The performance of the catalyst particles prepared in Examples 1-5 and Comparative Examples 1-3 was tested.
[0084] 1. Catalytic activity of toluene
[0085] Test conditions: Toluene concentration 500 ppm, remainder air, total flow rate 300 mL / min. -1 The reaction mass hourly space velocity (MHV) is 120,000 mL·h. -1 ·g -1 The mass hourly space velocity (MHV) refers to the amount of gas processed per gram of catalyst per hour, which is equivalent to a catalyst dosage of 0.15 g under the gas flow rate conditions specified in this test. The test results are shown in Table 1 and... Figure 1 and Figure 2 .
[0086] Table 1
[0087]
[0088] Figure 1 Catalysts prepared with different organic ligands and mixed organic ligands were used to catalytically oxidize toluene. Figure 1 As can be seen, the catalytic activity of Examples 3 to 5 is better than that of Examples 1 and 2 overall, with Example 3 showing the best activity. This indicates that the catalytic activity of the catalyst prepared by the mixed organic ligand is significantly better than that of the catalyst prepared by the single organic ligand, and that 2-methylimidazole and terephthalic acid are relatively suitable mixed organic ligands.
[0089] Figure 2 Catalytic oxidation curves of toluene prepared by different methods are shown in the figure. Figure 2 As can be seen, the catalyst prepared in Example 3 exhibits the best catalytic activity compared to the catalysts in Comparative Examples 1 and 2 that did not use organic ligands and Comparative Example 3 that did not use organic solvents.
[0090] 2. Catalytic activity of ethyl acetate
[0091] Test conditions: Ethyl acetate concentration 2000 ppm, remainder air, total flow rate 300 mL / min. -1 The reaction mass hourly space velocity (MHV) is 120,000 mL·h. -1 g -1 That is, under the gas flow rate conditions of this test, the catalyst dosage is 0.15g. The test results are as follows: Figure 3 As shown.
[0092] from Figure 3 As can be seen, the catalyst prepared in Example 3 exhibits the best catalytic activity in the catalytic oxidation of ethyl acetate.
[0093] 3. Catalyst stability
[0094] Test conditions: 0.15 g of the catalyst prepared in Example 3 was placed in a reaction tube, and the temperature was raised to 250 °C at a rate of 10 °C / min. A continuous toluene catalytic oxidation reaction was then carried out at this temperature for 12 hours. Afterward, the temperature was raised to 290 °C at a rate of 10 °C / min, and the continuous toluene catalytic oxidation reaction was carried out at this temperature for another 12 hours. The toluene concentration was 500 ppm, the remainder was air, and the total flow rate was 300 mL / min. -1 The reaction mass hourly space velocity (MHV) is 120,000 mL·h. -1 ·g -1 .
[0095] from Figure 4As can be seen from the data, the catalyst prepared in Example 3 maintained an activity of over 56% after being stable at 250℃ for 12 hours and maintained an activity of over 99% after being stable at 290℃ for 12 hours, indicating that the catalyst has good stability.
[0096] 4. Crystallization performance test
[0097] Test conditions: X-ray diffraction analysis was performed using a Rigaku RING / MAX-2500PC X-ray diffractometer (Japan). The excitation source was Cu Kα rays with a wavelength of 1.54056 Å, a tube current of 200 mA, and a tube voltage of 40 kV. The scanning range was 2θ = 10°–80°, the scanning speed was 5° / min, and the step size was 0.02°. Phase analysis of the samples was performed by referring to the JCPDS (Joint Powder Diffraction Standards Database).
[0098] from Figure 5 As can be seen from the X-ray diffraction patterns, the catalysts prepared in Examples 1 to 5 all have a certain degree of crystallinity and exhibit a CeO2 phase.
[0099] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0100] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.
Claims
1. The application of a cerium-based VOCs purification catalyst in the catalytic removal of VOCs gas, characterized in that, The preparation method of the cerium-based VOCs purification catalyst includes the following steps; (1) Disperse the organic ligand and the cerium precursor in N,N-dimethylformamide to obtain an organic ligand solution and a cerium solution, wherein the organic ligand is composed of two organic ligands, 2-methylimidazole and pyromellitic acid or 2-methylimidazole and terephthalic acid; (2) The organic ligand solution obtained in step (1) is added to the cerium solution to carry out a hydrothermal reaction, and a solid product is obtained after solid-liquid separation; (3) The solid product obtained in step (2) is washed, dried and calcined to obtain catalyst particles.
2. The application of the cerium-based VOCs purification catalyst according to claim 1 in the catalytic removal of VOCs gas, characterized in that, The molar ratio of the two organic ligands is 10:1 to 1:
10.
3. The application of the cerium-based VOCs purification catalyst according to claim 1 in the catalytic removal of VOCs gas, characterized in that, The organic ligand is composed of 2-methylimidazole and pyromellitic acid.
4. The application of the cerium-based VOCs purification catalyst according to any one of claims 1-3 in the catalytic removal of VOCs gas, characterized in that, In step (1), the concentration of the organic ligand solution is 0.1~2 mmol / mL, and the concentration of the cerium solution is 0.01~0.2 mmol / mL.
5. The application of the cerium-based VOCs purification catalyst according to claim 1 in the catalytic removal of VOCs gas, characterized in that, In step (1), the cerium precursor contains at least one of Ce(NH4)2(NO3)6 and Ce(NO3)3·6H2O.
6. The application of the cerium-based VOCs purification catalyst according to claim 1 in the catalytic removal of VOCs gas, characterized in that, In step (2), the molar ratio of the organic ligand in the ligand solution to the cerium element in the cerium solution is 1:1 to 12:1; and / or, the reaction temperature of the hydrothermal reaction is 100 to 150 °C. o C, the reaction time is 10~24h.
7. The application of the cerium-based VOCs purification catalyst according to claim 1 in the catalytic removal of VOCs gas, characterized in that, The VOCs gas includes at least one of benzene and esters; and / or, the temperature of the catalytic reaction is 200-320°C. o C.