Preparation and application of hydrophobic manganese-based ozone catalytic material

Abstract

The present application relates to a kind of hydrophobic manganese-based ozone catalytic material preparation and application.Catalytic material preparation method first uses coprecipitation method to introduce other metal ions, by mixing salt solution and mixed alkali solution under heating condition, centrifugal, washing, drying to obtain initial product;It is dissolved in deionized water, modifier is added, and it is reacted under heating condition, after reaction, it is washed and dried to obtain catalytic material.The hydrophobic ozone decomposition catalytic material prepared by the present application has abundant acid sites and good hydrophobic hydrotalcite sample, which shows excellent ozone decomposition capacity under high humidity condition.The hydrotalcite material prepared by the present application is synthesized by introducing other metal ions into a new type of five-membered hydrotalcite, which has high ozone decomposition performance.

Description

Technical Field

[0001] This invention belongs to the field of inorganic functional materials technology, and particularly relates to the preparation and application of a hydrophobic manganese-based ozone catalytic material. Background Technology

[0002] Ozone is a greenhouse gas, primarily composed of volatile organic compounds (VOCs) and nitrogen oxides (NOx). x Ozone is formed through photochemical reactions between molecules. Increased atmospheric ozone concentrations pose a significant threat to human health. Inhaling ozone can lead to weakened lung function and damage to epithelial cells. Furthermore, ozone is harmful to plant species; prolonged exposure can reduce seed yields and accelerate aging, severely impacting plant productivity. Ozone also reacts rapidly with building materials and home furnishings containing unsaturated organic compounds, causing problems such as dye fading, image layer discoloration, and tire aging. Therefore, research on ozone decomposition is of great significance for human health, environmental protection, and resource conservation.

[0003] Current literature reports ozone removal methods including thermal decomposition, adsorption decomposition, chemical absorption, and electromagnetic radiation decomposition; however, these methods still suffer from relatively low efficiency, high energy consumption, and secondary pollution. Catalytic decomposition, due to its cleanliness, high efficiency, and lack of secondary pollution, has become the most effective method for ozone removal.

[0004] The high cost of precious metals limits their application in practical production, while transition metal oxide catalysts, being inexpensive and abundant in nature, have become the most attractive active components. Among them, MnOx is one of the most promising oxides due to its excellent decomposition activity and low cost. Dhandapani and Oyama reported that MnO2 exhibited the highest ozone decomposition activity compared to other transition metal oxides supported on γ-Al2O3. Furthermore, many studies have shown that the catalytic activity of MnO2 for ozone decomposition is related to its multiple valence states, diverse structures, different morphologies, and surface oxygen vacancies. However, the accumulation of water or intermediate oxygen species during the reaction gradually deteriorates the catalytic performance. Therefore, there is an urgent need to develop a catalyst with high activity and high efficiency and moisture resistance. Summary of the Invention

[0005] The objective of this invention is to design a hydrophobic material to improve ozone decomposition performance under high humidity conditions.

[0006] In view of the technical problems existing in the prior art, this invention designs a method for preparing and applying a hydrophobic manganese-based ozone catalytic material. This invention increases the number of acidic sites by introducing other metal ions into the quaternary hydrotalcite layer, and synthesizes a highly hydrophobic pentagonal hydrotalcite through sodium stearate modification. This pentagonal hydrotalcite possesses numerous acidic sites and highly efficient hydrophobic capabilities, significantly improving the ozone decomposition performance under high humidity conditions.

[0007] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition definition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," etc., and similar meanings.

[0008] To solve the aforementioned technical problems, the present invention adopts the following solution:

[0009] [The first technical solution]

[0010] The preparation method of the manganese-based anti-ozone aging agent of the present invention is as follows: it is synthesized by co-precipitation method.

[0011] The preparation of a hydrophobic manganese-based ozone catalytic material is characterized by comprising the following steps:

[0012] Step 1: Place M 2+ and M 3+ Prepare a salt solution from a soluble salt; M a+ The soluble salt is dissolved in citric acid solution to prepare M. a+ A citric acid solution; the two solutions mentioned above are mixed to prepare a mixed salt solution.

[0013] Step 2: Weigh out the strong base, sodium salt, and hexadecyltrimethylammonium bromide (CTAB), dissolve them in deionized water to make a mixed alkaline solution;

[0014] Step 3: Add the mixed salt solution obtained in Step 1 and the mixed alkali solution obtained in Step 2 into a three-necked flask through a constant pressure funnel. The pH needs to be maintained at 9-11 throughout the process. React under heating conditions, centrifuge, wash, and dry to obtain the initial product.

[0015] Step 4: Weigh the initial product obtained in step 3 and dissolve it in deionized water. Place it in a three-necked flask, add the modifier, and react under heating conditions. After the reaction is complete, wash and dry to obtain the hydrophobic manganese-based ozone catalyst.

[0016] The hydrophobic manganese-based ozone catalytic material has a hydrotalcite structure;

[0017] [M 2+ 1-(x+y) M 3+ y Ma+ x (OH)2] q+ (A n- ) q / n •mH2O

[0018] Among them, M 2+ M represents the divalent metal cations on the plate. 2+ For Mn 2+ Combination with other soluble divalent metal cations;

[0019] M 3+ Represents the trivalent metal cations on the plate.

[0020] M a+ These represent trivalent or tetravalent metal cations on the representative layer;

[0021] M 2+ With M 3+ The molar ratio is 2-4:1.

[0022] Furthermore, the M mentioned above 2+ For Mn 2+ and Mg 2+ Ni 2+ Zn 2+ Ca 2+ Co 2+ Cu 2+ A combination of the two;

[0023] The M mentioned 3+ For Al 3+ Cr 3+ Fe 3+ and Ga 3+ One of them;

[0024] The M mentioned a+ Zr 4+ Ce 3+ Ga 3+ One of them.

[0025] Furthermore, the M mentioned above 2+ M 3+ Soluble salts refer to chlorides or nitrates;

[0026] Where Mn 2+ In M 2+ The proportion of medium molar ratio is 0.1-0.7;

[0027] M a+ With Mn 2+ The molar ratio is 0.2-0.5.

[0028] Furthermore, in step 1, the concentration of the citric acid solution is 0.2 M;

[0029] In step 2, the strong alkali is sodium hydroxide or potassium hydroxide;

[0030] The sodium salt mentioned is one of sodium carbonate, sodium chloride, sodium nitrate, and sodium sulfate;

[0031] The amount of strong alkali added is 1.5-2.5 times the total cation molar ratio;

[0032] The amount of sodium salt added is such that it satisfies the requirements of interlayer anions and M. 3+ The molar ratio is 1-6;

[0033] The amount of hexadecyltrimethylammonium bromide (CTAB) added is 8% of the total molar amount of the metal.

[0034] Furthermore, in step 3, the reaction under heating conditions refers to the reaction under conditions of 50-80℃ in a water bath for 2-4 hours.

[0035] In step 4, the modifier is one of sodium stearate, sodium dodecyl sulfonate, perfluorooctyltriethoxysilane, and dodecylfluoroheptyl methacrylate.

[0036] The mass of the modifier is 1%-10% of the mass of the initial product;

[0037] The reaction under heating conditions refers to the reaction at 70-90℃ for 2-3 hours.

[0038] In this invention, the M 2+ Mn is preferred 2+ and Ni 2+ Co 2+ Combination methods;

[0039] In this invention, the M 3+ Al is preferred 3+ ;

[0040] In this invention, the M a+ Zr is preferred 4+ .

[0041] In this invention, the soluble cobalt salt is cobalt nitrate or cobalt chloride, the soluble nickel salt is nickel nitrate or nickel chloride, the soluble manganese salt is manganese nitrate or manganese chloride, the soluble aluminum salt is aluminum nitrate or aluminum chloride, and the soluble Zr salt is zirconium oxynitrate.

[0042] In this invention, Mn is defined as follows: 2+ In M 2+The proportion means that the molar ratio of the other two soluble divalent metal cations in all divalent metal cations can be any value, and their amount does not affect the performance of the subsequent product.

[0043] In step 2, according to experimental needs, 0.1-1000 times the total mass of solids is added to deionized water to dissolve and prepare a mixed alkaline solution.

[0044] In this invention, the centrifugation process does not have specific requirements for the rotation speed, as long as a good solid-liquid separation effect is achieved. Similarly, the washing process does not have specific limitations on the number of washes, continuing until the solution is neutral. In some embodiments, the centrifugation speed can be 2500-4000 rpm, and the number of washes is 5-6.

[0045] The hydrophobic manganese-based ozone decomposition catalyst proposed in this invention is a layered double hydroxide (LDH), also known as hydrotalcite. Due to its unique layered structure and the tunable nature of its interlayer ions, layered hydrotalcite, with its supramolecular structure, is currently widely used in catalysis, photoelectric applications, and thermal stabilizers.

[0046] The selection of three divalent cations, one trivalent cation, and one other metal ion to synthesize the hydrotalcite structure in this invention has unique significance:

[0047] Manganese-free hydrotalcite typically lacks efficient redox cycle centers and mainly captures ozone through surface physical adsorption and weak chemical adsorption. The reaction mechanism is limited, resulting in low decomposition efficiency under high ozone concentrations and poor water resistance.

[0048] In the hydrotalcite selected in this invention, Mn provides redox activity and has multiple variable valence states that constitute an efficient redox cycle. Introducing Mn into the hydrotalcite layers effectively stabilizes and disperses manganese active sites within its layered structure. The other two divalent cations in the system synergistically work with Mn to stabilize the structure and regulate the electronic environment. Trivalent metal ions can regulate the charge density of the layers, further influencing the acidic sites of the catalyst. The introduction of other metal ions can modulate the electronic environment of the active metals, interacting with the divalent and trivalent metal ions in the layers to further stabilize the layered structure of the hydrotalcite and regulate the surface acidity of the catalyst, affecting the adsorption and activation of ozone. The synergistic effect of these five metals jointly optimizes the catalytic performance.

[0049] In a preferred embodiment of the present invention, Mn is selected. 2+ and Ni 2+ Co 2+ Combination methods, M 3+ Al is preferred 3+The M mentioned a+ Zr is preferred 4+ It will have excellent effects, and the mechanism is as follows:

[0050] Mn provides variable valence states and redox activity, Ni stabilizes the layered structure of the hydrotalcite and optimizes the redox capacity of Mn, Co and Mn have a synergistic effect, which can accelerate the rate of the entire redox cycle, Al, as a trivalent metal ion, provides a stable, positively charged layered framework, and the introduction of Zr can adjust the surface acidity of the catalyst, which is beneficial to the contact and activation of ozone on the surface. Zr interacts with other layered metal ions to stabilize the structure of the hydrotalcite and enhance catalytic activity. The five metals in the hydrotalcite selected in this invention work together to construct a highly efficient and stable catalytic system, thereby improving the activity of ozone decomposition.

[0051] In this invention, Zr in the highly hydrophobic ozone decomposition material 4+ It is easily hydrolyzed and requires pre-complexation of its nitrate and citric acid to form a stable complex, resulting in a clear and transparent solution.

[0052] In this invention, the alkaline solution and the metal salt solution need to be added slowly and vigorously stirred to avoid excessively high local concentrations and the generation of impurities.

[0053] In this invention, the final wash solution after centrifugation is taken, and AgNO3 solution is added. If no white precipitate forms, CTAB has been completely removed. Otherwise, residual CTAB will clog the pipeline and affect the catalytic performance.

[0054] [Second Technical Solution]

[0055] The present invention also discloses a hydrophobic manganese-based ozone catalytic material, which is prepared according to the above preparation method.

[0056] Furthermore, its general chemical formula is [M 2+ 1-(x+y) M 3+ y M a+ x (OH)2] q+ (A n- ) q / n •mH2O

[0057] M 2+ and M 3+ These represent divalent and trivalent metal cations on the plate, respectively;

[0058] M a+ The metal cations introduced on the representative layer;

[0059] An- Interlayer anions;

[0060] n is the charge number of the anion;

[0061] x+y is M 3+ +M a+ With M 2+ +M 3+ +M a+ The molar ratio has a range of 0.1 ≤ x ≤ 0.5;

[0062] m represents the number of water molecules in the interlayer, and its value ranges from 0 to m and from 6 to 6.

[0063] Furthermore, the M mentioned above 2+ For Mn 2+ and Mg 2+ Ni 2+ Zn 2+ Ca 2+ Co 2+ Cu 2+ A combination of the two;

[0064] The M mentioned 3+ For Al 3+ Cr 3+ Fe 3+ and Ga 3+ One of them;

[0065] The M mentioned a+ Zr 4+ Ce 3+ Ga 3+ One of them;

[0066] The A mentioned n- It is one of the following: carbonate, nitrate, chloride, and sulfate.

[0067] Furthermore, the M mentioned above 2+ With M 3+ The molar ratio is 2-4:1.

[0068] Mn 2+ In M 2+ The proportion in the middle is 0.1-0.7%;

[0069] M a+ With Mn 2+ The molar ratio is 0.2-0.5.

[0070] [The third technical solution]

[0071] The present invention also discloses the use of the above-mentioned hydrophobic manganese-based ozone catalyst in ozone decomposition.

[0072] The specific application methods are as follows:

[0073] Before loading, the prepared catalyst is dried at 60-80℃, and particles of 40-60 mesh are screened out for later use. This catalyst is then loaded into a fixed-bed catalyst reactor and can be used in scenarios such as ozone generator workshops and wastewater treatment plants where ozone-containing waste gas is generated.

[0074] It can also be used in air purifiers with ozone disinfection function, medical ozone disinfection cabinets, car air purifiers, etc. It can also be used in places that can generate ozone, such as libraries, laboratories, and archives. It is also very suitable for high humidity environments, such as the plum rain season in the south or aquaculture workshops.

[0075] This invention provides a method for preparing and applying a hydrophobic manganese-based ozone catalytic material, which has the following beneficial effects:

[0076] 1. The high-efficiency hydrophobic ozone decomposition material of the present invention has abundant acidic sites and good hydrophobicity. The hydrotalcite sample exhibits excellent ozone decomposition ability under high humidity conditions.

[0077] 2. The hydrotalcite material prepared by this invention is a novel pentagonal hydrotalcite synthesized by introducing other metal ions, thus preparing an ozone decomposition material with high moisture resistance.

[0078] 3. The highly efficient hydrophobic ozone decomposition material prepared in this invention has abundant acidic sites and good hydrophobicity. The synergistic effect of these two properties can effectively improve the ozone decomposition performance under high humidity conditions. Further research on the hydrophilicity and hydrophobicity of this material using water contact angles shows that hydrotalcite with water contact angles greater than 95° has excellent resistance to wet ozone decomposition. Attached Figure Description

[0079] Figure 1 : XRD patterns of CoNiMnAl-Zr-CO3-LDH-SS and CoNiMnAl-CO3-LDH-SS prepared in Example 1;

[0080] Figure 2 : NH3-TPD spectra of the CoNiMnAl-Zr-CO3-LDH-SS prepared in Example 1 and the products prepared in Comparative Examples 1 and 2;

[0081] Figure 3 : A schematic diagram of the water contact angle of CoNiMnAl-Zr-CO3-LDH-SS prepared in Example 1;

[0082] Figure 4 : This is a graph showing the ozone decomposition performance of CoNiMnAl-Zr-CO3-LDH-SS prepared in Example 1. Detailed Implementation

[0083] The present invention will be further described below with reference to specific embodiments and accompanying drawings:

[0084] Example 1:

[0085] Step 1: According to the cation ratio Co / Ni / Mn / Al / Zr molar ratio = 1:1:1:1:0.5, Mn 2+ In M 2+ The proportion of middle is 1 / 3; M 2+ With M 3+ The molar ratio is 3:1; in step 2, M a+ With Mn 2+ The molar ratio is 0.5.

[0086] Prepare 50 mL of 0.2 M citric acid solution, weigh 5.78 g of ZrO(NO3)2 and add it to the citric acid solution. According to the molar ratio of Zr:citric acid = 1:2, add 9.60 g of citric acid. Stir in a water bath at 40℃ for 30 minutes to form a completely clear solution.

[0087] Weigh 14.55 g Co(NO3)2·6H2O, 14.54 g Ni(NO3)2·6H2O, 8.96 g Mn(NO3)2, and 18.76 g Al(NO3)3·9H2O, mix and dissolve in deionized water;

[0088] The two solutions are mixed and dissolved together in 100 mL of deionized water to form a mixed salt solution.

[0089] Step 2: Weigh 16.00 g NaOH, 10.60 g Na2CO3, and 4.16 g CTAB and dissolve them together in 100 mL of deionized water to form a mixed alkaline solution.

[0090] Step 3: Add the mixed salt solution and mixed alkali solution to the three-necked flask through a constant pressure funnel. The pH needs to be maintained at 9-11 throughout the process. React in a water bath at 60°C for 2 hours. After the reaction is complete, centrifuge at 3000 rpm and wash 5-6 times until the solution is neutral. Finally, freeze-dry the sample in a freeze dryer to obtain the initial product, denoted as CoNiMnAl-Zr-CO3-LDH.

[0091] Weigh 5 g of dried CoNiMnAl-Zr-CO3-LDH and dissolve it in 100 mL of deionized water. Place the solution in a three-necked flask and add sodium stearate at 5% of the mass of CoNiMnAl-Zr-CO3-LDH. React at 80 °C for 2 h.

[0092] Step 4: After the reaction is complete, cool to room temperature, remove the sample, wash and dry it to obtain the desired sample CoNiMnAl-Zr-CO3-LDH-SS.

[0093] The sample was sieved to 40-60 mesh using a 40-60 mesh sieve for ozone decomposition performance testing.

[0094] The crystal structure of the samples prepared above was characterized using an X-ray diffractometer.

[0095] The results are as follows Figure 1 As shown, the sample conforms to the standard characteristic peaks of the layered structure of LDHs, and the prepared CoNiMnAl-Zr-CO3-LDH-SS sample exhibits a typical ordered layered structure without other impurities. The diffraction peak at 2θ = 11.1° is marked as the (003) plane of LDHs, indicating that carbonate ions were successfully intercalated between the LDHs layers. Compared with CoNiMnAl-CO3-LDH, the (003) peak is shifted to the left, indicating that Zr was successfully inserted into the layers, and the crystallinity is reduced, possibly due to the local lattice distortion caused by the introduction of Zr.

[0096] The samples prepared above were characterized for acidic sites using NH3-TPD.

[0097] The results are as follows Figure 2 As shown, peaks below 200℃ are attributed to weak acids, peaks between 200-400℃ are moderately strong acids, and peaks above 400℃ are strong acids. The total number of acidic sites can be calculated to be 52.2 mmol / g based on the peak areas.

[0098] The hydrophilicity and hydrophobicity of the prepared samples were characterized by water contact angle testing.

[0099] The results are as follows Figure 3 As shown, the water contact angle is 103.2°, indicating that the sample has good hydrophobicity, which is beneficial to ozone decomposition performance under high humidity conditions.

[0100] The prepared samples were placed in a fixed-bed continuous flow quartz reactor. Ozone was introduced, and the ozone concentrations at the inlet and outlet of the quartz tube reactor were measured to evaluate the ozone catalytic decomposition performance. The results are as follows: Figure 4 As shown.

[0101] The formula for calculating ozone conversion rate is: ,

[0102] Where C in and C out It refers to the inlet and outlet concentrations of ozone.

[0103] At RH = 90%, Cin At a concentration of 120 ppm, the ozone decomposition efficiency is 171.43 μmol g. -1 min -1 .

[0104] Example 2

[0105] Example 2 is the same as Example 1, except that:

[0106] In step 1, the cation ratio Co / Ni / Mn / Al / Zr molar ratio is 45:45:10:50:2, which means Mn 2+ In M 2+ The proportion of M is 0.1%; 2+ With M 3+ The molar ratio is 2:1; in step 2, M a+ With Mn 2+ The molar ratio is 0.2.

[0107] Weigh 13.10 g Co(NO3)2·6H2O, 13.09 g Ni(NO3)2·6H2O, 1.79 g Mn(NO3)2, 18.75 g Al(NO3)3·9H2O, weigh 0.46 g ZrO(NO3)2, add 0.77 g citric acid according to the Zr:citric acid molar ratio of 1:2, weigh 12.16 g NaOH, 10.60 g Na2CO3, and 4.43 g CTAB.

[0108] The sample in this embodiment conforms to the standard characteristic peaks of LDH layered structure, and the prepared CoNiMnAl-Zr-CO3-LDH-SS sample exhibits a typical ordered layered structure, free of other impurities. The water contact angle is 101.3° at RH = 90% and C... in At a concentration of 120 ppm, the ozone decomposition efficiency is 150.42 μmol g. -1 min -1 CoNiMnAl-Zr-CO3-LDH was prepared.

[0109] Example 3

[0110] Example 3 is the same as Example 1, except that:

[0111] In step 1, the cation ratio Co / Ni / Mn / Al / Zr molar ratio is 3:3:14:5:7, which means Mn 2+ In M 2+ The proportion of M is 0.7%; 2+ With M 3+ The molar ratio is 4:1; in step 2, Ma+ With Mn 2+ The molar ratio is 0.5.

[0112] Weigh 4.36 g Co(NO3)2·6H2O, 4.36 g Ni(NO3)2·6H2O, 12.53 g Mn(NO3) 2， 9.38 gAl(NO3)3·9H2O, weigh 8.09 g ZrO(NO3) 2， According to the Zr:citric acid molar ratio of 1:2, 13.45 g of citric acid was added, and 12.80 g of NaOH, 5.30 g of Na2CO3, and 8.60 g of CTAB were weighed out. CoNiMnAl-Zr-CO3-LDH was prepared.

[0113] The sample in this embodiment conforms to the standard characteristic peaks of LDH layered structure, and the prepared CoNiMnAl-Zr-CO3-LDH-SS sample exhibits a typical ordered layered structure, free of other impurities. The water contact angle is 98.5° at RH = 90% and C... in At a concentration of 120 ppm, the ozone decomposition efficiency is 142.56 μmol g. -1 min -1 .

[0114] Example 4

[0115] Example 4 is the same as Example 1, except that in step 1, the cation ratio Mg / Zn / Mn / Fe / Ce is 1:1:1:1:0.2. The difference is that: Mn 2+ and Mg 2+ Zn 2+ The combination of and ; the M mentioned 3+ For Fe 3+ The M mentioned a+ For Ce 3+ In step 3, the reaction under heating conditions refers to the reaction at 50°C in a water bath for 4 hours. In step 4, the modifier is perfluorooctyltriethoxysilane; the mass of the modifier is 1% of the mass of the initial product; the reaction under heating conditions refers to the reaction at 70°C for 3 hours.

[0116] Step 1: According to the cation ratio Mg / Zn / Mn / Fe / Ce molar ratio = 1:1:1:1:0.2, Mn 2+ In M 2+ The proportion of middle is 1 / 3; M 2+ With M 3+ The molar ratio is 3:1; M a+ With metal ions Mn 2+ The ratio is 0.2.

[0117] Weigh 10.16 g MgCl2·6H2O, 6.81 g ZnCl2, 9.89 g MnCl2·4H2O, 13.51 g FeCl3·6H2O, and 2.46 g CeCl3·7H2O, and dissolve them together in 100 mL of deionized water to form a mixed salt solution.

[0118] Step 2: Weigh 23.56 g KOH, 5.84 g NaCl, and 6.12 g CTAB and dissolve them together in 100 mL of deionized water to form a mixed alkaline solution.

[0119] Step 3: Add the mixed salt solution and mixed alkali solution to the three-necked flask through a constant pressure funnel. The pH needs to be maintained at 9-11 throughout the process. React in a water bath at 50°C for 4 hours. After the reaction is complete, centrifuge at 3000 rpm and wash 5-6 times until the solution is neutral. Finally, freeze-dry the sample in a freeze dryer to obtain the initial product, denoted as MgZnMnFe-Ce-CO3-LDH.

[0120] Weigh 5g of dried MgZnMnFe-Ce-CO3-LDH and dissolve it in 100 mL of deionized water. Place the solution in a three-necked flask and add 1% of perfluorooctyltriethoxysilane (FOTs) by mass of MgZnMnFe-Ce-CO3-LDH. React at 70°C for 3 h.

[0121] Step 4: After the reaction is complete, cool to room temperature, take out the sample, wash and dry it to obtain the desired sample MgZnMnFe-Ce-CO3-LDH-FOTs.

[0122] Example 5

[0123] Example 5 is the same as Example 1, except that in step 1, the cation ratio Ca / Cu / Mn / Cr / Ga molar ratio is 1:1:1:1:0.2. The difference is that Mn... 2+ and Ca 2+ Cu 2+ The combination of; the M 3+ For Cr 3+ The M mentioned a+ For Ga 3+ In step 3, "reaction under heating conditions" refers to a reaction at 80°C in a water bath for 3 hours. "Reaction under heating conditions" also refers to a reaction at 90°C for 2 hours.

[0124] Step 1: According to the cation ratio Ca / Cu / Mn / Cr / Ga molar ratio = 1:1:1:1:0.2, Mn 2+ In M 2+The proportion of middle is 1 / 3; M 2+ With M 3+ The molar ratio is 3:1;

[0125] Weigh 7.35 g CaCl2·2H2O, 8.52 g CuCl2·2H2O, 9.89 g MnCl2·4H2O, 13.32 g CrCl3·6H2O, and 4.18 g Ga(NO3)3·9H2O, and dissolve them together in 100 mL of deionized water to form a mixed salt solution.

[0126] Step 2: Weigh 8.40 g NaOH, 14.20 g Na2SO4, and 6.12 g CTAB and dissolve them together in 100 mL of deionized water to form a mixed alkaline solution.

[0127] Step 3: Add the mixed salt solution and mixed alkali solution to the three-necked flask through a constant pressure funnel. The pH needs to be maintained at 9-11 throughout the process. React in a water bath at 80°C for 3 hours. After the reaction is complete, centrifuge at 3000 rpm and wash 5-6 times until the solution is neutral. Finally, freeze-dry the sample in a freeze dryer to obtain the initial product, denoted as CaCuMnCrGa-SO4-LDH.

[0128] Weigh 5 g of dried CaCuMnCrGa-SO4-LDH and dissolve it in 100 mL of deionized water. Place the solution in a three-necked flask and add 10% (by weight of CaCuMnCrGa-SO4-LDH) of dodecafluoroheptyl methacrylate (DFHMA). React at 90 °C for 2 h.

[0129] Step 4: After the reaction is complete, cool to room temperature, remove the sample, wash and dry it to obtain the desired sample CaCuMnCrGa-SO4-LDH-DFHMA.

[0130] The catalysts prepared in Examples 4-5 also exhibit water contact angles exceeding 95°, demonstrating good hydrophobicity. Under RH = 90% conditions, their ozone decomposition efficiency reaches 140.00 μmol g. -1 min -1 It has good ozone decomposition performance.

[0131] Comparative Example 1:

[0132] The preparation method is the same as in Example 1, except that Zr is not introduced to obtain the desired CoNiMnAl-CO3-LDH.

[0133] The crystal structure of the samples prepared above was characterized using an X-ray diffractometer.

[0134] The results are as follows Figure 1 As shown, the sample conforms to the standard characteristic peaks of the layered structure of LDHs, and the prepared CoNiMnAl-CO3-LDH sample exhibits a typical ordered layered structure without other impurities. The diffraction peak at 2θ = 11.5° is marked as the (003) plane of LDHs, indicating that carbonate ions were successfully intercalated between the LDH layers.

[0135] The samples prepared above were characterized for acidic sites using NH3-TPD.

[0136] The results are as follows Figure 2 As shown, peaks below 200℃ are attributed to weak acids, peaks between 200-400℃ are attributed to moderately strong acids, and peaks above 400℃ are attributed to strong acids. The total number of acidic sites can be calculated to be 11.45 mmol / g based on the peak areas.

[0137] Comparative Example 2:

[0138] The preparation method is the same as in Example 1, except that sodium stearate is not introduced to obtain the desired CoNiMnAlZr-CO3-LDH.

[0139] The prepared sample was characterized by X-ray diffraction. The sample conformed to the standard characteristic peaks of LDH layered structure, and the prepared CoNiMnAlZr-CO3-LDH sample exhibited a typical ordered layered structure without other impurities. The diffraction peak at 2θ = 11.5° was marked as the (003) plane of LDH, indicating that carbonate ions were successfully intercalated between the LDH layers.

[0140] The samples prepared above were characterized for acidic sites using NH3-TPD. The results are as follows: Figure 2 As shown, peaks below 200℃ are attributed to weak acids, peaks between 200-400℃ are moderately strong acids, and peaks above 400℃ are strong acids. The total number of acidic sites can be calculated to be 34.80 mmol / g based on the peak areas.

[0141] Comparative Examples 1 and 2 primarily verified the effects of the modifier and Zr on acidic sites. The results demonstrate that the introduction of both the modifier and Zr can alter the number of acidic sites to varying degrees.

[0142] Zr 4+ These are strong Lewis acid sites. Their introduction can significantly increase the acidic sites on the catalyst surface and change the electronic environment of the surrounding metal ions, thereby better regulating the redox properties of the main active center and enhancing the stability of the hydrotalcite structure.

[0143] Modifiers such as sodium stearate can effectively alter the electronic structure of metal sites through electron-withdrawing induction, making the metal sites stronger Lewis acids, increasing the number of Lewis acid sites, promoting ozone contact and activation on the surface, and further improving ozone decomposition performance under high humidity conditions.

[0144] The present invention has been described above by way of example with reference to the embodiments and accompanying drawings. Obviously, the implementation of the present invention is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A method for preparing a hydrophobic manganese-based ozone catalytic material, characterized in that, Includes the following steps: Step 1: Place M 2+ and M 3+ Prepare a salt solution from a soluble salt; M a+ The soluble salt is dissolved in citric acid solution to prepare M. a+ A citric acid solution; the two solutions mentioned above are mixed to prepare a mixed salt solution. Step 2: Weigh out the strong base, sodium salt, and hexadecyltrimethylammonium bromide, dissolve them in deionized water to make a mixed alkaline solution; Step 3: Add the mixed salt solution obtained in Step 1 and the mixed alkali solution obtained in Step 2 into a three-necked flask through a constant pressure funnel. The pH needs to be maintained at 9-11 throughout the process. React under heating conditions, centrifuge, wash, and dry to obtain the initial product. Step 4: Weigh the initial product obtained in step 3 and dissolve it in deionized water. Place it in a three-necked flask, add the modifier, and react under heating conditions. After the reaction is complete, wash and dry to obtain the hydrophobic manganese-based ozone catalyst. The hydrophobic manganese-based ozone catalytic material has a hydrotalcite structure; [M 2+ 1-(x+y) M 3+ y M a+ x (OH)2] q+ (A n- ) q / n •mH2O wherein M 2+ represents a divalent metal cation on the layer, M 2+ is Mn 2+ and combinations of other soluble divalent metal cations; M 3+ representing a trivalent metal cation on the layer sheet, M a+ represents a trivalent or tetravalent metal cation on the layer sheet M 2+ With M 3+ The molar ratio is 2-4:1; The M 2+ is Mn 2+ and Mg 2+ , Ni 2+ , Zn 2+ , Ca 2+ , Co 2+ , Cu 2+ in combination of two The M 3+ is one of Al 3+ , Cr 3+ , Fe 3+ and Ga 3+ ; The M a+ is Zr 4+ , Ce 3+ , Ga 3+ one of The M 2+ , M 3+ soluble salt means a chloride or nitrate salt; wherein Mn 2+ In M 2+ The molar ratio of 0.1-0.

7. M a+ with a molar ratio of Mn 2+ 0.2-0.5; In step 4, the modifier is one of sodium stearate, sodium dodecyl sulfonate, perfluorooctyltriethoxysilane, and dodecylfluoroheptyl methacrylate.

2. The preparation method of the hydrophobic manganese-based ozone catalytic material according to claim 1, characterized in that: In step 1, the concentration of the citric acid solution is 0.2 M; In step 2, the strong alkali is sodium hydroxide or potassium hydroxide; The sodium salt mentioned is one of sodium carbonate, sodium chloride, sodium nitrate, and sodium sulfate; The amount of strong alkali added is 1.5-2.5 times the total cation molar ratio; The amount of the sodium salt added is such that the molar ratio of the interlayer anion to M 3+ is 1-6. The amount of hexadecyltrimethylammonium bromide added is 8% of the total molar amount of the metal.

3. The preparation method of the hydrophobic manganese-based ozone catalytic material according to claim 1, characterized in that: In step 3, the reaction under heating conditions refers to the reaction being carried out in a water bath at 50-80℃ for 2-4 hours. The mass of the modifier is 1%-10% of the mass of the initial product; The reaction under heating conditions refers to the reaction at 70-90℃ for 2-3 hours.

4. A hydrophobic manganese-based ozone catalytic material, characterized in that: It is prepared according to the preparation method described in any one of claims 1-3.

5. The hydrophobic manganese-based ozone catalytic material according to claim 4, characterized in that: with the general chemical formula [M 2+ 1-(x+y) M 3+ y M a+ x (OH)2] q+ (A n- ) q / n •mH2O in, M 2+ and M 3+ represent divalent and trivalent metal cations on the layer, respectively; M a+ represents a metal cation introduced on the layer; A n- Interlayer anions; n is the charge number of the anion; x+y is M 3+ +M a+ with M 2+ +M 3+ +M a+ in a molar ratio of 0.1≤x≤0.

5. m represents the number of water molecules in the interlayer, and its value ranges from 0 to m and from 6 to 6.

6. The hydrophobic manganese-based ozone catalytic material according to claim 5, characterized in that: The M 2+ is Mn 2+ and Mg 2+ , Ni 2+ , Zn 2+ , Ca 2+ , Co 2+ , Cu 2+ in combination of two The M 3+ is one of Al 3+ , Cr 3+ , Fe 3+ and Ga 3+ . The M a+ is Zr 4+ , Ce 3+ , Ga 3+ one of The A n- is one of carbonate, nitrate, chloride, sulfate.

7. The hydrophobic manganese-based ozone catalytic material according to claim 4, characterized in that: The M mentioned 2+ With M 3+ The molar ratio is 2-4:1; Mn 2+ In M 2+ 0.1-0.7; M a+ with a molar ratio of Mn 2+ 0.2-0.

5.

8. Use of the hydrophobic manganese-based ozone catalyst of claim 4 in ozone decomposition.

Images