A preparation method of an epsilon / delta-manganese dioxide composite material and a formaldehyde patch prepared by the same
Formaldehyde removal patches are made by synthesizing ε/δ-MnO2 composite materials at low temperatures, which solves the problems of high temperature requirements, precious metal load and secondary pollution of existing formaldehyde removal products. It achieves efficient catalytic degradation of formaldehyde at room temperature and is flexible and safe for use.
Patent Information
- Application Number
- CN202411950089.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2044-12-27
AI Technical Summary
Existing formaldehyde removal products have problems such as high temperature requirements, precious metal load, low energy efficiency, limited application scenarios, and easy to cause secondary pollution. In addition, the unevenness of the spray and the release of formaldehyde after the activated carbon adsorption is saturated can cause secondary pollution.
An ε/δ-MnO2 composite material was prepared by low-temperature synthesis and then made into a formaldehyde removal patch. This patch can catalytically oxidize formaldehyde into carbon dioxide and water at room temperature, thus avoiding secondary pollution.
It achieves efficient catalytic degradation of formaldehyde at room temperature, with excellent removal and conversion rates, flexible application scenarios, no secondary pollution, and high safety.
Smart Images
Figure CN119746847B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of formaldehyde catalytic materials, in particular to a preparation method of an epsilon / delta-MnO2 composite material and a formaldehyde sticker prepared therefrom. BACKGROUND
[0002] At present, formaldehyde, as an important harmful component of indoor pollution, mainly comes from building materials and furniture, which can pose a potential threat to human health. Exposure to high concentrations of formaldehyde can cause dizziness, tearing, allergies, bronchitis, leukemia and other symptoms, and even death in severe cases. In the 2017 carcinogen list published by the International Agency for Research on Cancer of the World Health Organization, formaldehyde is listed as a class 1 carcinogen. Therefore, how to efficiently remove formaldehyde without causing secondary pollution has become an important focus of scientific research. However, in previous studies, although the catalysts prepared have good catalytic degradation effect on formaldehyde, they usually have problems such as the need for high temperature conditions, the loading of expensive noble metals (Pt, Au, Ag, Pd, etc.) and the high demand for light intensity, which brings great challenges to practical application. Manganese dioxide has become the focus of current research due to its diversified crystal form, multiple valence state, good low-temperature catalytic ability and excellent environmental compatibility. However, the traditional preparation method of manganese dioxide is mainly through microwave, hydrothermal and other methods, which has low energy utilization rate and is not conducive to large-scale production and application.
[0003] The current market mainstream formaldehyde removal products have spray type formaldehyde remover, activated carbon and filter screen used with large equipment. The spray type formaldehyde remover mainly degrades formaldehyde in the air by dissolving formaldehyde catalyst into a solution and then spraying the solution in the form of mist, although it is simple to use and has a certain effect on removing formaldehyde, but it has many disadvantages. First, the release of formaldehyde is a long-term process, and the spray type formaldehyde remover can only reduce the formaldehyde content in the air in the short term, so it needs to be frequently sprayed. Second, the use of the spray largely depends on the uniformity and coverage of the spraying, so when the spraying is not uniform, the formaldehyde in some areas cannot be effectively removed. Third, the tiny solid particles left after the evaporation of the spray can cause particulate pollution, and some chemical components can cause irreversible damage to organisms and human health. In addition, long-term spraying of these high-solvent content spray type formaldehyde removers can also cause corrosion to furniture (wood components, etc.). At the same time, the use of formaldehyde sprays is also limited in space, such as kitchens, closets, and other places that have no contact with food, tableware, and skin, which are not suitable for use. As a simple formaldehyde adsorbent, activated carbon removes formaldehyde mainly through physical adsorption, and will reach adsorption saturation after a period of use. The adsorbed formaldehyde can also be re-released into the air, causing secondary pollution to the environment. Since the adsorbent such as activated carbon only spatially transfers formaldehyde, it cannot fundamentally remove formaldehyde. In addition, in a high-heat and high-humidity environment, the adsorption performance of activated carbon will rapidly decrease. The use of filter screen and large air equipment to remove formaldehyde is expensive and occupies a large area, and can only be used in fixed locations and consumes a large amount of electrical energy. Therefore, there is an urgent need to design a new type of formaldehyde removal product. SUMMARY
[0004] The purpose of the present application is to provide a preparation method of ε / δ-MnO2 composite material and a formaldehyde sticker prepared therefrom, so as to solve the above problems in the background art. The ε / δ-MnO2 composite material prepared by the present application has excellent catalytic degradation ability of formaldehyde at room temperature and under indoor fluorescent lamp, and excellent formaldehyde removal rate and conversion rate. The ε / δ-MnO2 composite material prepared by the present application can be made into a formaldehyde removal sticker, which can avoid the inconvenience of using existing formaldehyde removal products (such as sprays, etc.) and the limitation of use scene, and can be pasted in different occasions, with flexible use scene. The ε / δ-MnO2 composite material of the present application can remove formaldehyde at room temperature, and can completely catalyze the oxidation of formaldehyde into carbon dioxide and water, without causing secondary pollution.
[0005] To achieve the above purpose, the present application provides the following technical scheme:
[0006] One of the technical schemes of the present application provides a preparation method of ε / δ-MnO2 composite material, characterized in that it comprises the following steps:
[0007] Mixing MnCl2 and KMnO4 in a solvent to obtain a precursor solution, adjusting the pH value to pH=0.9-1.3, and aging to obtain the ε / δ-MnO2 composite material.
[0008] Preferably, the solvent is water.
[0009] Preferably, the molar ratio of MnCl2 to KMnO4 is 1.2:1.
[0010] The strong acid environment of the present application can enhance the oxidizing property of potassium permanganate, and is more conducive to the reaction. By adding excess potassium permanganate, the present application can ensure that the reaction is more complete.
[0011] Preferably, the concentration of manganese ions in the precursor solution is 0.12 mol / L.
[0012] Preferably, the pH value is adjusted by adding hydrochloric acid.
[0013] Preferably, the aging temperature is 25-30℃, and the aging time is 12-24h.
[0014] The second technical scheme of the present application provides an ε / δ-MnO2 composite material prepared by the above preparation method.
[0015] The third technical scheme of the present application provides a formaldehyde sticker, which is prepared by fixing the above ε / δ-MnO2 composite material on the outer side of a sticker.
[0016] Preferably, the formaldehyde sticker comprises a sticker with adhesion on the inner side, the ε / δ-MnO2 composite material covering the outer side of the sticker, and a filter screen for fixing the ε / δ-MnO2 composite material.
[0017] The fourth technical scheme of the present application provides an application of the above ε / δ-MnO2 composite material or formaldehyde sticker in the field of formaldehyde removal.
[0018] Compared with the traditional hydrothermal method for preparing MnO2 material, the present application proposes a method for effectively synthesizing ε / δ-MnO2 at low temperature. The present application selects MnCl2 as a raw material to prepare ε / δ-MnO2 with higher formaldehyde catalytic performance, and the product also has certain photocatalytic activity.
[0019] The formaldehyde sticker of the present application can be customized into any shape, can be used in more complex environments, will not cause secondary pollution, will not affect human health, and is more safe.
[0020] The beneficial technical effects of the present application are as follows:
[0021] The prepared epsilon / delta-MnO2 composite material has excellent catalytic degradation ability of formaldehyde at room temperature and under indoor fluorescent lamp, and has excellent formaldehyde removal rate and conversion rate. The prepared epsilon / delta-MnO2 composite material is made into a formaldehyde removal sticker, which can avoid the problems of inconvenient use and limited use scene of existing formaldehyde removal products (such as sprays), and can be pasted in different occasions, and has flexible use scene.
[0022] The epsilon / delta-MnO2 composite material can remove formaldehyde at room temperature, and can completely catalyze oxidation of formaldehyde into carbon dioxide and water, and does not cause secondary pollution. BRIEF DESCRIPTION OF DRAWINGS
[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.
[0024] Figure 1 XRD patterns of products of examples 1-3 and comparative examples 1-4.
[0025] Figure 2 Formaldehyde concentration change graph of products of examples 1-3 and comparative examples 1-4 during the test.
[0026] Figure 3 Carbon dioxide concentration change graph of products of examples 1-3 and comparative examples 1-4 during the test.
[0027] Figure 4 Cycle experiment graph of example 2.
[0028] Figure 5 UV-Vis diffuse reflectance spectrum graph of products of example 2 and comparative example 1 (the insert is the band gap graph of products of example 2 and comparative example 1).
[0029] Figure 6 Electrochemical impedance spectrum graph of products of example 2 and comparative example 1.
[0030] Figure 7 Structure schematic diagram of formaldehyde sticker of example 4. Wherein: 1 epsilon / delta-MnO2 composite material, 2 film net, 3 front sticker paper clothing, 4 main body sticker.
[0031] Figure 8 Formaldehyde conversion performance graph of products of examples 1-3 and comparative examples 1-4.
[0032] Figure 9A photograph of a formaldehyde patch made from the ε / δ-MnO2 composite material of Example 2. DETAILED DESCRIPTION
[0033] The following detailed description of various example embodiments of the application is not to be considered limiting of the scope or spirit of the application, but rather as a description of certain examples and aspects of the application, and as an exemplification of the application's certain features and embodiments. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting of the application.
[0034] Further, for numerical ranges that are expressed in a range format, it is intended that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range is also specifically disclosed. Each smaller range that falls within the integer ranges is also specifically disclosed. The upper and lower limits of these smaller ranges can independently be included or excluded in the range, and are also encompassed within the application, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of the limits are also included.
[0035] Unless defined otherwise, 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 application belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described.
[0036] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended and do not exclude additional elements or steps.
[0037] As used herein, the term "room temperature" means 10-30°C, unless otherwise specified.
[0038] The raw materials used in the following examples and comparative examples of the present application are commercially available.
[0039] Example 1
[0040] A method for preparing an ε / δ-MnO2 composite material, comprising the following steps:
[0041] 2.376 g of MnCl2-H2O (0.012 mol) was weighed into a beaker containing 100 mL of ultrapure water and stirred for 10 min. Then 1.58 g of KMnO4 (0.01 mol) was added, and the pH value was adjusted to pH = 1.3 by adding hydrochloric acid. After stirring for 1 h, the stirrer was removed by a magnet, and the mixture was aged at 30°C for 12 h. After aging, the mixture was washed by centrifugation with ultrapure water and ethanol, respectively. Finally, the mixture was dried in an oven at 80°C for 18 h to obtain an ε / δ-MnO2 composite material.
[0042] Example 2
[0043] A preparation method of an ε / δ-MnO2 composite material, steps as follows:
[0044] Take 2.376g MnCl2·H2O (0.012mol), put into a beaker containing 100mL ultrapure water and stir for 10min, then add 1.58g KMnO4 (0.01mol), and adjust the pH value to pH=1.3 by adding hydrochloric acid, stir for 1h, then remove the stirrer with a magnet, place at 30℃ for aging, aging time is 18h, after aging, sequentially wash with ultrapure water and ethanol, finally dry in an oven, drying temperature is 80℃, time is 18h, to obtain an ε / δ-MnO2 composite material.
[0045] Example 3
[0046] A preparation method of an ε / δ-MnO2 composite material, steps as follows:
[0047] Take 2.376g MnCl2·H2O (0.012mol), put into a beaker containing 100mL ultrapure water and stir for 10min, then add 1.58g KMnO4 (0.01mol), and adjust the pH value to pH=1.3 by adding hydrochloric acid, stir for 1h, then remove the stirrer with a magnet, place at 30℃ for aging, aging time is 24h, after aging, sequentially wash with ultrapure water and ethanol, finally dry in an oven, drying temperature is 80℃, time is 18h, to obtain an ε / δ-MnO2 composite material.
[0048] Comparative Example 1
[0049] A preparation method of an ε / δ-MnO2 composite material, steps as follows:
[0050] Take 2.376g MnCl2·H2O (0.012mol), put into a beaker containing 100mL ultrapure water and stir for 10min, then add 1.58g KMnO4 (0.01mol), and adjust the pH value to pH=1.3 by adding hydrochloric acid, stir for 1h, then remove the stirrer with a magnet, place at 30℃ for aging, aging time is 24h, after aging, sequentially wash with ultrapure water and ethanol, finally dry in an oven, drying temperature is 80℃, time is 18h, to obtain an ε / δ-MnO2 composite material.
[0051] Comparative Example 2
[0052] A preparation method of an ε / δ-MnO2 composite material, steps as follows:
[0053] Take 3.012 g of Mn(NO3)2·4H2O (0.012 mol), put it into a beaker containing 100 mL of ultrapure water and stir for 10 min, then add 1.58 g of KMnO4 (0.01 mol), and adjust the pH to 1.3 by adding nitric acid, stir for 1 h, then remove the stirrer with a magnet, and let it stand at 30°C for 18 h. After aging, wash it with ultrapure water and ethanol by centrifugation, and finally dry it in an oven at 80°C for 18 h to obtain the ε / δ-MnO2 composite material.
[0054] Comparative Example 3
[0055] A method for preparing a δ-MnO2 catalyst, the steps being as follows:
[0056] Take 20 mL of C2H5OH, put it into a beaker containing 80 mL of ultrapure water and stir for 10 min, then add 3.16 g of KMnO4 (0.02 mol), stir for 1 h, then remove the stirrer with a magnet, and let it stand at 30°C for 18 h. After aging, wash it with ultrapure water and ethanol by centrifugation, and finally dry it in an oven at 80°C for 18 h to obtain the δ-MnO2 catalyst.
[0057] Comparative Example 4
[0058] A method for preparing a ε-MnO2 catalyst, the steps being as follows:
[0059] Take 9.45 g of Mn(NO3)2·4H2O, put it into a beaker containing 70 mL of ultrapure water, and stir until the solution is clear to obtain a Mn(NO3)2 solution. Then dissolve 2.12 g of Na2CO3 in 70 mL of ultrapure water, and add it dropwise to the Mn(NO3)2 solution. Then adjust the pH of the solution to 8, and react at room temperature for 3 h to obtain a white solid. Centrifuge it, and then dry it in an oven at 80°C for 12 h. Then calcine the obtained white solid in a muffle furnace at a heating rate of 2°C / min from room temperature to 350°C, and keep it at 350°C for 4 h to obtain the ε-MnO2 catalyst.
[0060] Figure 1 XRD patterns of the products of Examples 1-3 and Comparative Examples 1-4.
[0061] From Figure 1It can be seen that diffraction peaks corresponding to δ-MnO2(JCPDS: 18-0802) and ε-MnO2(JCPDS: 30-0802) can be found in all of the examples 1-3 and comparative examples 1-2, which indicates that all of the five samples are ε / δ-MnO2 catalysts. However, only two weak diffraction peaks at 36.8° and 65.7° corresponding to (006) and (119) crystal planes of δ-MnO2 can be found in comparative example 3, which indicates that comparative example 3 is composed of δ-MnO2 only and has poor crystallinity. By comparing the XRD patterns of example 1-3 and comparative example 1-2, it can be seen that a broad peak at 20° appears in example 1-3, which is due to the overlapping of the diffraction peak of δ-MnO2 at 18.6° and the peak of ε-MnO2 at 21°. Comparative example 4 is prepared as monomer ε-MnO2, and diffraction peaks at about 56° appear in example 1-3, which further indicates that both ε-MnO2 and δ-MnO2 exist in example 1-3. And no obvious diffraction peak at 18.6° can be observed in comparative example 1-2, which is mainly due to its poor crystallinity.
[0062] Example 4
[0063] A method for preparing a formaldehyde sticker is as follows:
[0064] The ε / δ-MnO2 composite materials prepared in examples 1-3 are ground uniformly, and then the obtained catalyst powders are uniformly laid on one side of the double-sided adhesive tape. Due to the adhesion, the catalyst powders are fixed on the double-sided adhesive tape. In order to prevent the catalyst powders from falling off, a microporous filter film with a pore size of 0.45 μm is sealed on the surface of the catalyst powder layer, so that the catalyst powders can be prevented from falling off while air can quickly contact the catalyst, and a formaldehyde sticker is prepared.
[0065] Figure 9 A physical picture of the formaldehyde sticker prepared by using the ε / δ-MnO2 composite material of example 2.
[0066] Effect verification
[0067] Formaldehyde catalytic degradation experiment:
[0068] The performance of the catalysts prepared in Examples 1-3 and Comparative Examples 1-4 was tested in a 6L sealed chemical reactor lined with aluminum foil. The experimental procedure was as follows: first, 0.1 g of the sample was evenly spread on the surface of a 9 cm diameter petri dish, and the interaction of the catalyst with formaldehyde was adjusted by opening and closing the lid; then, the initial concentrations of water and carbon dioxide were adjusted to the same level by treating with a desiccant and sodium hydroxide as the experimental environment; then, a 38% mass fraction formaldehyde solution was injected into the system through the inlet using a syringe, and air circulation in the sealed chemical reactor was promoted by a 5w fan, and the light and dark environment was controlled by turning on and off the fluorescent lamp inside the sealed reactor, the test temperature was 25°C, and the test duration was 36 min. The test results are shown in Table 1.
[0069] The formula for the removal rate of formaldehyde is: (initial concentration - final concentration) / initial concentration.
[0070] The formula for the conversion rate of formaldehyde is: (final concentration of carbon dioxide - initial concentration of carbon dioxide) / initial concentration of formaldehyde.
[0071] Table 1: Removal and conversion efficiency of formaldehyde by samples under light / dark conditions
[0072]
[0073] Table 1 lists the removal efficiency of formaldehyde and the conversion efficiency of formaldehyde of all samples under light and dark conditions. It can be seen that the removal efficiency of formaldehyde of Examples 1-3 under dark conditions is 86.7%, 94.3% and 90.8% respectively, and the removal efficiency of formaldehyde under light is 87.9%, 88.8%, 85.8%, which is significantly higher than the 84.3%, 80.7%, 55.2%, 38.7% of Comparative Examples 1-4 under dark conditions and the 78.8%, 80.9%, 49.3%, 46.2% under light. The difference between the examples and the comparative examples in the conversion efficiency of formaldehyde is even greater than the removal efficiency. The conversion efficiency of formaldehyde of Examples 1-3 under dark conditions is 67.8%, 73%, 59% respectively, and the conversion efficiency of formaldehyde under light is 72.7%, 83.6%, 70.1% respectively, which is much higher than the 44%, 38.5%, 0%, 0% of Comparative Examples 1-4 under dark conditions and the 63.5%, 41.7%, 1%, 4.1% under light. For the same example, the conversion efficiency of formaldehyde under light is higher than the conversion efficiency of formaldehyde under dark conditions for the example. This indicates that the examples have good photocatalytic activity.
[0074] Figure 2 Figure of the change of formaldehyde concentration of the products of Examples 1-3 and Comparative Examples 1-4 during the test.
[0075] Figure 3 The carbon dioxide concentration change graph of the products of Examples 1-3 and Comparative Examples 1-4 during the test.
[0076] Figure 2 With Figure 3 The performance test graph of the prepared samples shows that the removal ability for formaldehyde is: Example 2 > Example 1 > Example 3 > Comparative Example 1 > Comparative Example 2 > Comparative Example 4 > Comparative Example 3, and the conversion ability for formaldehyde is: Example 2 > Example 1 > Example 3 > Comparative Example 1 > Comparative Example 2 > Comparative Example 4 > Comparative Example 3. Comparative Example 3 shows the worst formaldehyde removal ability compared with other samples, because Comparative Example 3 is only composed of δ-MnO2, and the pure phase δ-MnO2 has poor oxidation efficiency for formaldehyde at 25°C, and the pure phase ε-MnO2 also shows poor catalytic activity, which also indicates that the incorporation of ε-MnO2 and δ-MnO2 exists interaction, and can effectively improve the formaldehyde catalytic performance of the catalyst of the application.
[0077] The results of the cycle experiment under the above formaldehyde catalytic degradation experiment conditions are shown in Figure 4 .
[0078] Figure 4 The cycle experiment graph of Example 2 is shown in
[0079] Figure 4 The results show that Example 2 has good cycle stability and still has high removal ability for formaldehyde after four cycles.
[0080] Figure 5 The UV-Vis diffuse reflectance spectra of the products of Example 2 and Comparative Example 1 (the inset is the band gap diagram of the products of Example 2 and Comparative Example 1) are shown in
[0081] It can be seen from Figure 5 that the DRS spectrum proves that the prepared MnO2 has strong absorption ability for the entire solar spectrum, and Example 2 has stronger light absorption ability than Comparative Example 1. In addition, according to the linear extrapolation method, the band gaps of Example 2 and Comparative Example 1 are 2.32 eV and 2.41 eV, respectively. Example 2 has a relatively narrower band gap, which is more conducive to light response and electron migration.
[0082] Figure 6 The electrochemical impedance spectrograms of the products of Example 2 and Comparative Example 1 are shown in
[0083] It can be seen from Figure 6 that Example 2 has a smaller diameter, indicating that the charge transfer resistance is smaller, i.e. the photoelectron hole pairs are more easily separated and transferred. This is consistent with the phenomenon that the catalytic oxidation of formaldehyde performance of Example is significantly enhanced under light conditions.
[0084] Figure 7 The structural schematic diagram of the formaldehyde sticker of Example 4. Wherein: 1 ε / δ-MnO2 composite material, 2 film net, 3 front sticker paper clothing, 4 main body sticker.
[0085] Figure 8 The formaldehyde conversion performance diagram of the products of Examples 1-3 and Comparative Examples 1-4.
[0086] From the above data, it can be seen that the formaldehyde removal and conversion performance of each example are higher than those of the comparative examples, and the performance of the examples can be further improved under light conditions. Figure 8
[0087] The above examples only describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.
Claims
1. Use of ε / δ-MnO2 composite material in the field of formaldehyde removal, characterized in that, The preparation method of the epsilon / delta-MnO2 composite material comprises the following steps: MnCl2 and KMnO4 are mixed in a solvent to obtain a precursor solution, the pH value is adjusted to pH=0.9-1.3, and aging is performed to obtain the epsilon / delta-MnO2 composite material; The solvent is water; The molar ratio of MnCl2 to KMnO4 is 1.2:1; The aging temperature is 25-30 DEG C, and the aging time is 12-24 h.
2. Use according to claim 1, characterized in that, The concentration of manganese ions in the precursor solution is 0.12 mol / L.
3. Use according to claim 1, characterized in that, The pH value is adjusted by adding hydrochloric acid.
Citation Information
Patent Citations
Method for preparing manganese dioxide nano rod at low temperature
CN102070196A