CN107138153B - In-situ growth layered manganese oxide loaded carbon fiber felt and synthesis method and application thereof - Google Patents

In-situ growth layered manganese oxide loaded carbon fiber felt and synthesis method and application thereof Download PDF

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CN107138153B
CN107138153B CN201710271860.2A CN201710271860A CN107138153B CN 107138153 B CN107138153 B CN 107138153B CN 201710271860 A CN201710271860 A CN 201710271860A CN 107138153 B CN107138153 B CN 107138153B
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阚晓天
王敏
张玲霞
施剑林
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Shanghai Institute of Ceramics of CAS
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Abstract

The invention relates to an in-situ growth layered manganese oxide loaded carbon fiber felt and a synthesis method and application thereof. The method uses nitric acid to pretreat the carbon fiber felt carrier, and then reacts with the activated carbon fiber felt through potassium permanganate solution under an acidic condition to generate the manganese oxide material loaded on the carbon fiber felt in situ.

Description

In-situ growth layered manganese oxide loaded carbon fiber felt and synthesis method and application thereof
Technical Field
The invention belongs to the field of environmental catalysis, relates to a layered manganese oxide-loaded carbon fiber felt material, and particularly relates to a novel, green and efficient crystallization catalyst for catalytic oxidation of low-concentration formaldehyde, and a preparation method and application thereof.
Background
In recent years, as cheap chemical raw materials such as phenolic resin and urea resin are widely added into products such as coating, plate adhesives and the like, the problem of indoor formaldehyde pollution is increasingly serious. It is well known that formaldehyde is strongly irritant and is a teratogenic carcinogen. Therefore, for human health, the removal of formaldehyde is imperative.
At present, the main means for removing formaldehyde at room temperature include adsorption, plasma oxidation, catalytic oxidation (combustion), photocatalytic oxidation, and the like. The thermal catalytic oxidation method is to utilize high-efficiency catalyst to catalytically degrade VOCs into CO2And H2O, it has the advantages of high catalytic efficiency, no secondary pollution, easy control of operation and the like, and is a technology with great prospect. The catalysts used for removing VOCs mainly include transition metal oxide catalysts and noble metal supported catalysts. A common transition metal oxide catalyst is Co3O4、MnOx、CeO2And the like. The noble metal catalyst is platinum, palladium, gold, silver, etc., which are usually supported on a transition metal oxide or a mixture thereof. Compared with noble metal catalysts, the transition metal oxide catalyst obviously has the advantages of low price, large reserves and the like.
Among the transition metal oxides, manganese oxide is widely used in many catalysts due to its characteristics of low cost and no toxicityIn the chemical reaction, for example, CO oxidation, etc. Among the various crystal forms of manganese oxide, the catalytic effect of Birnessite, namely delta-MnO 2, is particularly good, the manganese oxide is of a layered structure formed by MnO6 regular octahedron as a group, and a certain number of water molecules and different cations (such as Na +, K + and Ca2+) are arranged among manganese oxide layers. The unique layered structure of Birnessite makes it a highly efficient catalyst for the removal of carbon monoxide and Volatile Organic Compounds (VOCs). Zhang J, Li Y, Wang L, ethyl, catalytic oxidation of formaldehyde over manganese oxides with a differential structure [ J].Catalysis Science&Technology,2015,5(4):2305-2313.) delta-MnO was found2The catalyst has higher catalytic activity than α and gamma-MnO 2 when removing formaldehyde.
The active carbon fiber material is one of the very popular materials in recent years, is formed by stacking organic fibers such as flake graphite microcrystals and the like along the axial direction of the fiber, has a microporous structure, has a relatively high specific surface area, is rich in surface groups, is favorable for the adsorption of formaldehyde gas, and can provide sufficient space and sufficiently dispersed active sites.
Formaldehyde is a typical hazardous organic compound. On the one hand, it is harmful to the environment and to the human body, causing anesthetic diseases and increasing photochemical smog pollution. On the other hand, it is doubtful that the catalytic oxidation strategy is one of the most promising methods for the efficient removal of formaldehyde at room temperature. Applicant has found that the MnxCo3-xO4 catalyst can completely catalyze the oxidation of formaldehyde at 75 ℃ and the catalyst life is as long as 50 hours. Zhou et al (Zhou Xin Yan, Zhang 33411, Jiang Han, etc. manganese oxide modified activated carbon removes formaldehyde [ J ] in air. environmental engineering reports, 2015,9(12): 5965) and 5972.) successfully prepare MnOx/GAC catalyst by impregnation method, and the huge specific surface area of the activated carbon is utilized to adsorb formaldehyde in air, thus improving the catalytic reaction efficiency of manganese oxide. But the adopted activated carbon adsorbent easily causes the problem of secondary pollution.
Disclosure of Invention
In view of the above problems, the present invention provides a novel catalyst for removing low-concentration formaldehyde, and a preparation method and applications thereof.
In one aspect, the invention provides a layered manganese oxide-loaded carbon fiber felt material, which comprises a carbon fiber felt and a delta-phase manganese oxide nanosheet grown in situ on the surface of a carbon fiber in the carbon fiber felt, wherein the delta-phase manganese oxide nanosheet has a layered crystal structure.
The layered manganese oxide-loaded carbon fiber felt material comprises: the carbon fiber felt comprises a carbon fiber felt and delta-phase manganese oxide nanosheets growing on the surfaces of carbon fibers in the carbon fiber felt in situ. The carbon fiber felt is used as an active carbon fiber material, is formed by piling up organic fibers such as flake graphite microcrystals and the like along the axial direction of the fiber, has a microporous structure, a relatively high specific surface area and abundant surface groups, is beneficial to the adsorption of formaldehyde gas, and can provide sufficient space and sufficiently dispersed active sites. In addition, the delta-phase manganese oxide nanosheets grown in situ on the surfaces of the carbon fibers in the carbon fiber felt have a layered crystal structure, and can provide more active sites to catalyze formaldehyde more effectively. In addition, the carbon fiber material loaded with the layered manganese oxide has different surface oxygen species (surface adsorbed oxygen, oxygen-containing group oxygen species on the surface of the carbon fiber and lattice oxygen) and certain low-temperature reducibility (the manganese oxide has certain low-temperature reducibility, the low-temperature reducibility is obtained by an H2-TPR experiment, and a first peak of the low-temperature reducibility corresponds to the low-temperature reducibility), which is beneficial to the catalytic oxidation reaction and can realize the purpose of removing low-concentration formaldehyde at room temperature.
Preferably, the content of the delta-phase manganese oxide nanosheet in the layered manganese oxide-loaded carbon fiber felt material is 21-24 wt%.
Preferably, the specific surface area of the layered manganese oxide-loaded carbon fiber felt material is 25.75-47.42 m2The diameter of the mesoporous pore canal is 14-19 nm.
On the other hand, the invention also provides a preparation method of the layered manganese oxide-loaded carbon fiber felt material, which comprises the following steps:
pretreating the carbon fiber felt by using strong oxidizing acid;
and (2) dipping the pretreated carbon fiber felt into a potassium permanganate solution, adding a certain amount of acid to enable the pH of the potassium permanganate solution to be 1-2, then reacting for 3-9 hours at the temperature of 60-80 ℃, washing, and drying at the temperature of 60-100 ℃ to obtain the layered manganese oxide-loaded carbon fiber felt material.
According to the invention, the carbon fiber felt is pretreated by using strong oxidizing acid, so that the surface of the activated (pretreated) carbon fiber material has abundant active groups (such as hydroxyl, carboxyl and the like), and the activated (pretreated) carbon fiber material is easier to react with potassium permanganate. Then, placing the activated (pretreated) carbon fiber material in a potassium permanganate solution, adding a certain amount of hydrochloric acid to enable the pH value of the potassium permanganate solution to be 1-2, and carrying out water bath heating to enable the potassium permanganate to react with carbon fibers in the carbon fiber felt: c +2KMnO4=K2MnO4+MnO2+ CO2 × (C @), resulting in layered manganese oxide (MnO) in the end2) Growing the carbon fiber felt material on the surface of the carbon fiber in situ to obtain the layered manganese oxide-loaded carbon fiber felt material, wherein the layered manganese oxide nanosheet material which is well crystallized is loaded on the carbon fiber.
Preferably, the carbon fiber felt is placed in strong oxidizing acid and heated in water bath for 3-5 hours at the temperature of 60-80 ℃ to obtain the pretreated carbon fiber felt.
Preferably, the strong oxidizing acid is selected from nitric acid or/and sulfuric acid, preferably concentrated nitric acid with a concentration of 69%.
Preferably, the mass ratio of the carbon fiber felt to the potassium permanganate is (2-4): 10.
preferably, the drying temperature is 60-100 ℃, and the drying time is 10-14 hours.
Preferably, the acid is hydrochloric acid or sulfuric acid, preferably hydrochloric acid with the concentration of 1-3 mol/L.
On the other hand, the invention also provides an application of the carbon fiber felt material loaded with the layered manganese oxide in formaldehyde catalysis.
The main advantages of the invention are:
the method uses nitric acid to pretreat the carbon fiber felt carrier, and then reacts with the activated carbon fiber felt through potassium permanganate solution under an acidic condition to generate the manganese oxide material loaded on the carbon fiber felt in situ. The catalyst provided by the invention is a carbon fiber material loaded with delta-phase manganese oxide nanosheets, wherein the manganese oxide nanosheets are of a layered crystal structure. Its layered crystal structure will contribute to providing more active sites. And the active carbon fiber material as the matrix has a porous structure, which is beneficial to adsorbing formaldehyde gas. The carbon fiber material loaded with the layered manganese oxide has different surface oxygen species and certain low-temperature reducibility, which are beneficial to the catalytic oxidation reaction.
Drawings
FIG. 1 is an FTIR spectrum of a carbon fiber mat material before and after activation;
FIG. 2 is an XRD pattern of different layered manganese oxide loaded carbon fiber materials and carbon fiber matrix materials prepared in examples 1-3;
fig. 3 is an SEM image and a TEM image of the layered manganese oxide-loaded carbon fiber material prepared in example 1;
FIG. 4 is an SEM image and a TEM image of the layered manganese oxide-loaded carbon fiber material prepared in example 2;
FIG. 5 is an SEM image and a TEM image of the layered manganese oxide-loaded carbon fiber material prepared in example 3;
FIG. 6 shows H of different carbon fiber materials loaded with layered manganese oxide prepared in examples 1 to 32-a TPR map;
FIG. 7 is O of different layered manganese oxide loaded carbon fiber materials prepared in examples 1-32-a TPD map;
FIG. 8 is NH of different layered manganese oxide loaded carbon fiber materials prepared in examples 1-33-a TPD map;
FIG. 9 is a graph of the catalytic efficiency over time for various layered manganese oxide-loaded carbon fiber materials prepared in examples 1-3 for formaldehyde removal.
Detailed Description
The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.
The layered manganese oxide-loaded carbon fiber felt material provided by the invention comprises a carbon fiber felt and a delta-phase manganese oxide nanosheet growing on the surface of carbon fiber in the carbon fiber felt in situ. Wherein the manganese oxide material (delta-phase manganese oxide nanosheet) is delta-MnO with good crystallization2. The layered manganese oxide-loaded carbon fiber felt material is provided with mesoporous channels, and the diameters of the mesoporous channels can be 14-19 nm. The specific surface area of the layered manganese oxide-loaded carbon fiber felt material is about 25.75-47.42 m2(ii) in terms of/g. Wherein delta-MnO2Has a layered crystal structure. In addition, the layered manganese oxide-loaded carbon fiber felt material also has certain low-temperature reducibility and different surface oxygen species. The content of the delta-phase manganese oxide nanosheet in the layered manganese oxide-loaded carbon fiber felt material can be 21-24 wt%.
The method comprises the steps of pretreating the carbon fiber felt by using strong oxidizing acid, and then loading the activated (pretreated) carbon fiber felt with the layered manganese oxide nanosheets. The preparation method of the layered manganese oxide-loaded carbon fiber felt material provided by the invention is exemplarily described below.
The carbon fiber felt is pretreated with a strong oxidizing acid. Specifically, the carbon fiber felt is placed in a strong oxidizing acid and heated in a water bath for 3 to 5 hours at 60 to 80 ℃ (for example, 70 ℃) to obtain the pretreated carbon fiber felt. The strong oxidizing acid can be at least one of nitric acid and sulfuric acid, and is preferably concentrated nitric acid with the concentration of 69%.
And loading layered manganese oxide nanosheets (delta-phase manganese oxide nanosheets) on the activated carbon fiber felt. Specifically, the carbon fiber felt material loaded with the layered manganese oxide is obtained by immersing the pretreated carbon fiber felt in a potassium permanganate solution, adding a certain amount of acid (such as hydrochloric acid, dilute sulfuric acid and the like) to adjust the pH value of the potassium permanganate solution to 1-2, reacting for 3-9 hours (such as 6 hours) at 60-80 ℃ (preferably 60-70 ℃, such as 65 ℃), washing, and drying at 60-100 ℃. Wherein the mass ratio of the carbon fiber felt to the potassium permanganate is (2-4): 10. the drying temperature can be 60-100 ℃, and the drying time can be 10-14 hours. The concentration of the hydrochloric acid can be 1-3 mol/L, such as 2 mol/L.
In a preferred scheme, a nitric acid solution is used for activating carbon fibers, and then an oxidation-reduction reaction between a potassium permanganate solution and the activated carbon fibers is utilized to prepare the activated carbon fiber felt catalyst of the supported lamellar manganese oxide material in a water bath at 65 ℃.
In a preferred embodiment, (a) a carbon fiber felt is pretreated with a nitric acid solution; (B) and loading the activated carbon fiber felt with layered manganese oxide nanosheets. In step (A), 2.5g of carbon fiber felt is treated with a certain amount of concentrated nitric acid solution with the concentration of 69% for 3-5 hours in a water bath at 70 ℃, and then washed and dried to obtain an activated carbon fiber felt material, which is marked as CF acid treatment. In step (B), 0.048mol of KMnO is added at 65 ℃4Dissolving the activated carbon fiber felt material in 100mL of water, violently stirring the mixture until the activated carbon fiber felt material is completely dissolved, then dropwise adding a certain amount of hydrochloric acid solution (2mol/L) to adjust the pH value of the solution to 1-2, reacting for 6 hours, taking out the solution, washing the solution, and drying the solution in an oven at 80 ℃ to obtain the layered manganese oxide-loaded carbon fiber felt material prepared by the in-situ growth method. Wherein, the nitric acid used in the step A) can be other acids with strong oxidizing property.
The manganese oxide in the catalyst is delta-phase manganese oxide with good crystallization, has a two-dimensional nanosheet shape and a layered crystal structure, and has a high specific surface area and a mesoporous structure, certain low-temperature reducibility and abundant surface oxygen species. When the catalyst is used for removing low-concentration formaldehyde, the catalytic efficiency of the material to formaldehyde in 5h is about 30%. The preparation method of the catalyst is simple and easy, is environment-friendly, has low cost, and can be used as a catalyst for removing low-concentration formaldehyde gas or Volatile Organic Compound (VOC) gas by catalytic oxidation.
The layered manganese oxide-loaded carbon fiber felt material is used as a catalyst for catalyzing and removing low-concentration formaldehyde gas. The catalytic performance was evaluated by removing formaldehyde gas at a flow rate of 52L/min and a concentration of 1 ppm. The experimental procedure was as follows: approximately 13g of catalyst was cut into 25mm by 25mm square pieces, stacked and placed in a sample bin for testing. In the whole reaction process, sampling is carried out by using a phenol reagent every 0.5-1h, and after the phenol reagent and the ferric ammonium sulfate solution are subjected to color development reaction, the formaldehyde content is detected by using an ultraviolet spectrometer.
The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below. Test methods in which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under conditions recommended by the manufacturer. All percentages and parts are by weight unless otherwise indicated. Unless otherwise specified, the carbon fiber mats used in the following examples are all commercially available finished PAN carbon mats (prepared by pre-oxidizing and carbonizing polyacrylonitrile-based flat plate raw mats, and are more convenient to obtain and apply.
Example 1
2.5g of carbon fiber felt was treated with a certain amount of 69% concentrated nitric acid solution in a water bath at 70 ℃ for 3 hours, followed by washing and drying to obtain an activated carbon fiber felt material, which was designated as CF acid treatment. In step (B), 0.048mol of KMnO is added at 65 ℃4Dissolving the activated carbon fiber felt material in 100mL of water, violently stirring until the activated carbon fiber felt material is completely dissolved, then dropwise adding a certain amount of hydrochloric acid solution (2mol/L) to adjust the pH value of the solution to 2, reacting for 6 hours, taking out, washing and drying in an oven at 80 ℃, thus obtaining the layered manganese oxide-loaded carbon fiber felt material prepared by an in-situ growth method, which is recorded as 3h-CF, wherein the content of delta-phase manganese oxide nanosheets in the layered manganese oxide-loaded carbon fiber felt material is 21.8 wt%.
Example 2
In order to examine the influence of different reaction pH values on the formaldehyde removal performance of the catalyst, 2.5g of the carbon fiber felt is treated by a certain amount of concentrated nitric acid solution with the concentration of 69 percent for 3 hours in a water bath at 70 ℃,followed by washing and drying to provide an activated carbon fiber felt material, designated as CF acid treatment. In step (B), 0.048mol of KMnO is added at 65 ℃4Dissolving the activated carbon fiber felt material in 100mL of water, violently stirring until the activated carbon fiber felt material is completely dissolved, then dropwise adding a certain amount of hydrochloric acid solution (2mol/L) to adjust the pH value of the solution to 1, reacting for 6 hours, taking out, washing and drying in an oven at 80 ℃, so as to obtain the layered manganese oxide-loaded carbon fiber felt material prepared by an in-situ growth method, and marking the layered manganese oxide-loaded carbon fiber felt material as 3h-CF-pH1, wherein the content of delta-phase manganese oxide nanosheets in the layered manganese oxide-loaded carbon fiber felt material is 23.1 wt%.
Example 3
In order to examine the influence of different pretreatment times of nitric acid on the performance of the catalyst for removing formaldehyde, 2.5g of the carbon fiber felt was treated with a certain amount of concentrated nitric acid solution with the concentration of 69% for 5 hours in a water bath at 70 ℃, and then washed and dried to obtain an activated carbon fiber felt material, which is marked as CF acid treatment. In step (B), 0.048mol of KMnO is added at 65 ℃4Dissolving the activated carbon fiber felt material in 100mL of water, violently stirring until the activated carbon fiber felt material is completely dissolved, then dropwise adding a certain amount of hydrochloric acid solution (2mol/L) to adjust the pH value of the solution to 2, reacting for 6 hours, taking out, washing and drying in an oven at 80 ℃, thus obtaining the layered manganese oxide-loaded carbon fiber felt material prepared by an in-situ growth method, and marking the material as 5h-CF, wherein the content of delta-phase manganese oxide nanosheets in the layered manganese oxide-loaded carbon fiber felt material is 22.6 wt%.
FIG. 1 is an FTIR spectrum of a carbon fiber mat material before and after activation. As shown in figure 1, the activated carbon fiber felt after nitric acid pretreatment is 1300-1600 nm-1And 3400 to 3700nm-1Obvious stretching vibration peaks appear at the positions of the carbon fibers and respectively correspond to hydroxyl and carboxyl, which shows that after the carbon fibers are pretreated by nitric acid, active groups of the hydroxyl and the carboxyl appear on the surfaces of the carbon fibers, and the reaction of the carbon fibers and potassium permanganate is facilitated.
FIG. 2 is XRD spectra of different prepared carbon fiber materials and carbon fiber matrix materials loaded with layered manganese oxide. As can be seen from FIG. 2, the carbon fiber matrix is loaded with crystallized delta-MnO2(JCPDS 80-1098) in which 2 θ is 12.5 °,25 °,36.5 ° and 65.5 ° in degreesCorresponding to the (001), (002), (-111) and (-321) crystal planes, respectively. This indicates that the carbon fiber was successfully loaded with the manganese oxide material.
Fig. 3 is an SEM image and a TEM image of the carbon fiber material loaded with the layered manganese oxide prepared in example 1, in fig. 3, a and b are SEM images of a 3h-CF sample, and it can be found that the surface of the carbon fiber is uniformly loaded with the layered manganese oxide material, and in fig. 3, c is a TEM image of the 3h-CF sample, and it can be found that the manganese oxide material is in a layer shape. Fig. 4 is an SEM image and a TEM image of the carbon fiber material loaded with layered manganese oxide prepared in example 2, wherein a and b in fig. 4 are SEM images of 3h-CF-pH1 samples, it can be found that the manganese oxide material grown on the surface of the carbon fiber starts to agglomerate with the increase of reaction pH (meaning that the pH is increased from 2 to 1), and c in fig. 4 is a TEM image of 3h-CF-pH1 samples, it can be found that the manganese oxide material is still in a lamellar state. In FIG. 5, a and b are SEM images of 5h-CF samples, and it was found that the pretreatment time with nitric acid was increased while the pH was kept constant. The carbon fiber surface was corroded to some extent, and c in fig. 5 is a TEM image of a 5h-CF sample, and it can be found that the manganese oxide material is still lamellar.
FIG. 6 is H of different layered manganese oxide-loaded carbon fiber materials prepared2-a TPR map. As can be seen from fig. 6: the peak at low temperature corresponds to Mn4+To Mn3+The peak at the middle temperature corresponds to the reduction of the active oxygen-containing groups on the surface of the carbon fiber, and the peak at the high temperature corresponds to Mn3+To Mn2+The transformation of (3). As can be seen from the relative areas of the peaks: the reaction is more completely carried out along with the increase of the reaction pH value, and the surface active groups are reduced; with increasing nitric acid pretreatment time, the surface active groups increased and were not completely reacted away. Therefore, the carbon fiber material loaded with the layered manganese oxide also has certain low-temperature reducibility.
FIG. 7 is O of different layered manganese oxide-loaded carbon fiber materials prepared2-a TPD profile. As can be seen from fig. 7: the peak at low temperature corresponds to adsorbed oxygen species, the peak at medium temperature corresponds to carbon fiber surface active oxygen-containing radical oxygen species, and the peak at high temperature corresponds to lattice oxygen. Thus, carrying layered manganese oxideCarbon fiber materials also have different surface oxygen species.
FIG. 8 shows NH of different prepared carbon fiber materials loaded with layered manganese oxide3-a TPD profile. As can be seen from fig. 8: the peak of the low temperature section corresponds to the acid adsorption site of the catalyst, and the relative area of the peak shows that the acid sites on the surface of the 3h-CF-pH1 sample are less, which is more beneficial to the adsorption of formaldehyde gas.
Table 1 shows the mesoporous parameters of the carbon fiber felt material loaded with layered manganese oxide nanosheets prepared in examples 1 to 3:
Figure GDA0002326731720000071
effects of the embodimentThe formaldehyde removal experiments were performed under dynamic conditions. The gas flow rate was 52L/min and the formaldehyde concentration was 1 ppm. The experimental procedure was as follows: about 13g of the catalyst (the layered manganese oxide-supporting carbon fiber material prepared in examples 1 to 3) was cut into a square sheet-like material of 25mm × 25mm, stacked, and placed in a sample chamber for testing, and the amount of the catalyst used was 10g in total. In the whole reaction process, sampling is carried out by using a phenol reagent every 0.5-1h, and after the phenol reagent and the ferric ammonium sulfate solution are subjected to color development reaction, the formaldehyde content is detected by using an ultraviolet spectrometer. The formaldehyde removal efficiency was calculated according to the following formula: removal efficiency ═ CInlet port-CAn outlet)/CInlet port
FIG. 9 is a graph of the catalytic efficiency of different prepared carbon fiber materials loaded with layered manganese oxide as a function of time for removing formaldehyde. The catalytic efficiency of the manganese oxide-loaded carbon fiber felt materials prepared in examples 1 and 3 was 30% or less for formaldehyde gas having a concentration of 1ppm within 5 hours. The manganese oxide-loaded carbon fiber felt material prepared in example 2 has relatively high catalytic efficiency of about 30% for formaldehyde gas with a concentration of 1ppm within 5 hours.
All documents referred to herein are incorporated by reference into this application as if each were individually incorporated by reference. Furthermore, it should be understood that various changes and modifications of the present invention can be made by those skilled in the art after reading the above teachings of the present invention, and these equivalents also fall within the scope of the present invention as defined by the appended claims.

Claims (5)

1. The application of the layered manganese oxide-loaded carbon fiber felt material in formaldehyde catalysis is characterized in that the layered manganese oxide-loaded carbon fiber felt material comprises a carbon fiber felt formed by stacking flake graphite microcrystals along the axial direction of fibers and a delta-phase manganese oxide nanosheet growing on the surface of carbon fibers in the carbon fiber felt in situ, wherein the delta-phase manganese oxide nanosheet has a layered crystal structure; the content of delta-phase manganese oxide nanosheets in the layered manganese oxide-loaded carbon fiber felt material is 22.6-24 wt%; the specific surface area of the layered manganese oxide-loaded carbon fiber felt material is 25.75-47.42 m2The diameter of the mesoporous pore channel is 14-19 nm;
the preparation method of the layered manganese oxide-loaded carbon fiber felt material comprises the following steps:
placing the carbon fiber felt in strong oxidizing acid, and heating the carbon fiber felt in water bath at the temperature of 60-80 ℃ for 3-5 hours to obtain the pretreated carbon fiber felt, wherein the strong oxidizing acid is selected from nitric acid or/and sulfuric acid;
dipping the pretreated carbon fiber felt in a potassium permanganate solution, adding a certain amount of acid to enable the pH of the potassium permanganate solution to be 1-2, then reacting for 3-9 hours at the temperature of 60-80 ℃, and then washing and drying to obtain the layered manganese oxide-loaded carbon fiber felt material;
the mass ratio of the carbon fiber felt to the potassium permanganate is 2-4: 10.
2. use according to claim 1, characterized in that said strong oxidizing acid is selected from concentrated nitric acid with a concentration of 69%.
3. The use according to claim 1, wherein the drying temperature is 60-100 ℃ and the drying time is 10-14 hours.
4. Use according to claim 1, wherein the acid is hydrochloric acid or sulfuric acid.
5. The use according to claim 4, wherein the acid is hydrochloric acid having a concentration of 1 to 3 mol/L.
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