A titanium dioxide / manganese dioxide / carbon composite catalyst supported on a macroscopic carrier, a preparation method thereof, and applications thereof

Abstract

The present invention discloses a titanium dioxide / manganese dioxide / carbon composite catalyst supported on a macroscopic carrier, a preparation method thereof and an application. The preparation process is as follows: titanium dioxide is added to deionized water, stirred, potassium permanganate is added, and stirring is continued; a carbon source is added, after stirring evenly, a macroscopic carrier is added, ultrasonic mixing is carried out, and reaction is carried out under water bath conditions. After the reaction is completed, it is cooled and dried to obtain the product. Compared with the existing formaldehyde removal materials, through the mutual synergistic effect among the components of the composite catalyst in the present invention, that is, the photo-thermal synergistic catalytic oxidation under light conditions and the adsorption / catalytic oxidation under dark conditions act together to mineralize formaldehyde into environmentally harmless water and carbon dioxide. In addition, the preparation method of the present invention has a simple operation process and low raw material prices. Combining the support on a macroscopic carrier and the synergistic effect among the composite catalysts, it has the characteristics of a wide range of applicable scenarios, convenient subsequent recovery, and all-weather formaldehyde removal, and has broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of removal of formaldehyde, an organic pollutant gas, and particularly relates to a titanium dioxide / manganese dioxide / carbon composite catalyst supported on a macroscopic carrier, a preparation method thereof, and an application thereof. Background Art

[0002] Air pollution appears in many places, and air pollution in relatively enclosed spaces seriously endangers human health. For example, volatile organic gases emitted from furniture, paint, and decoration materials indoors subtly affect the health of people staying indoors for a long time. Most of them have been proven to cause more or less adverse physiological reactions or even diseases to the human body. Among them, formaldehyde was classified as a Group 1 carcinogen by the International Agency for Research on Cancer of the World Health Organization in 2017. It has a long release period, is colorless and has a pungent odor, and can only be detected by the human body at relatively high concentrations. Formaldehyde is more likely to exceed the standard in cars, especially in new cars, where the concentration can be more than ten times higher than the national indoor environmental standard. With the rapid development of the national economy and the improvement of people's living standards, the number of cars is increasing day by day, and the problem of polluted air in cars has reached a critical stage. In addition to the above scenarios, many living environments are facing formaldehyde gas pollution. Therefore, formaldehyde removal has become one of the problems that must be solved in today's society.

[0003] So far, there are various methods for removing formaldehyde. Adsorption using the adsorption method is the fastest and most convenient method. The adsorption method has a low cost, but the adsorption capacity is limited and needs to be replaced regularly. Oxidizing formaldehyde into environmentally friendly water and carbon dioxide is considered the most valuable method. For example, plasma catalytic oxidation, photocatalytic oxidation, thermal catalytic oxidation, photothermal catalytic oxidation, etc. Among them, photocatalytic oxidation uses the energy of sunlight to generate strongly oxidizing free radicals by the catalyst for the oxidation of formaldehyde. TiO2 is a common photocatalyst, but the photocatalytic oxidation of formaldehyde by single TiO2 is limited by problems such as poor visible light response and weak adsorption. Then, studies have been carried out on loading noble metals on TiO2, such as Pt, Pd, Ag, etc., which greatly improve the formaldehyde removal performance. Among the numerous studies on the thermal catalytic removal of formaldehyde, MnO2 has been widely studied due to its characteristics such as variable valence states, easy regulation, and many active sites. However, single MnO2 requires a relatively high temperature to efficiently remove formaldehyde. Similarly, it has been reported that loading noble metals can quickly remove formaldehyde in a short time, but the high cost limits its large-scale practical application. In addition, strategies such as alkali metal doping, carbon doping, and carbon composite can all make up for the shortcoming that thermal catalytic oxidation requires a relatively high working temperature. For example, the combination of activated carbon (AC) and MnO2 realizes the synergistic effect of adsorption / catalytic oxidation and improves the formaldehyde removal performance. The combination of graphene oxide and MnO2 utilizes the good photothermal conversion ability of graphene oxide to realize the photothermal synergistic effect. However, in the absence of light, the synergistic effect has no effect. From the current research reports, it can be seen that the existing composite catalysts have problems such as high cost and many restricted conditions, and none of them can meet the requirement of removing formaldehyde all-weather. Therefore, developing a formaldehyde removal material with high efficiency, low cost, good stability, few restricted conditions, and applicable to all-weather is the demand for realizing real practical applications.

[0004] The object of the present invention is to solve the problems of the current formaldehyde removal methods, such as many restricted conditions, low efficiency, difficult recovery, high cost, etc. The TiO2 / MnO2 / C composite catalyst is in-situ loaded on the macroscopic carrier, and the efficient removal of formaldehyde all-weather is realized by the photothermal synergistic catalytic oxidation under light conditions and the synergistic effect of adsorption / catalytic oxidation under dark conditions. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies of the existing technology and provide a titanium dioxide / manganese dioxide / carbon (TiO2 / MnO2 / C) composite catalyst loaded on a macroscopic carrier, which overcomes the problems of many restricted conditions and inability to continuously remove formaldehyde all-weather in the existing removal methods. Compared with the existing formaldehyde removal catalysts, the present invention realizes the continuous removal of formaldehyde all-weather in various environments by in-situ loading TiO2 / MnO2 / C on the macroscopic carrier and giving full play to the photothermal synergistic catalytic oxidation and the synergistic effect of adsorption / catalytic oxidation.

[0006] The present invention also provides a TiO2 / MnO2 / C composite catalyst loaded on a macroscopic carrier, its preparation method, and its application in formaldehyde removal under different conditions.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A preparation method of a TiO2 / MnO2 / C composite catalyst loaded on a macroscopic carrier is to in-situ grow TiO2 / MnO2 / C on the macroscopic carrier. The specific steps are as follows:

[0009] Add titanium dioxide into deionized water, stir, add potassium permanganate, and continue stirring; add a carbon source, stir evenly, then add the macroscopic carrier, perform ultrasonic mixing, react under water bath conditions, and after the reaction is completed, cool and dry to obtain the TiO2 / MnO2 / C composite catalyst loaded on the macroscopic carrier.

[0010] Specifically, the mass ratio of titanium dioxide to potassium permanganate is (1 - 4):(1 - 4). Specifically, the mass of titanium dioxide is 0.15 - 0.6 g, and the stirring time after adding titanium dioxide is 10 - 20 min; the mass of potassium permanganate is 0.15 - 0.6 g, and the stirring time after adding potassium permanganate is 5 - 10 min; the carbon source is one of glucose, fructose, glycogen, cellulose, sucrose, etc.; the macroscopic carrier is one of melamine sponge, activated carbon fiber cloth, and non-woven fabric, and the ultrasonic time is 5 - 20 min.

[0011] Further, the mass ratio of potassium permanganate to the carbon source is 20:(1 - 6); the water bath temperature is 70 - 90 °C, and the water bath time is 10 - 20 min. The drying temperature is 60 - 105 °C, and the drying time is 6 - 12 h; the stirring rate is 500 - 1000 rpm; the ultrasonic frequency is 25 - 40 kHz.

[0012] Further, the mass-volume ratio of titanium dioxide to the macroscopic carrier is (0.15 - 0.6) g:(15 - 30) cm 3 .

[0013] The present invention also provides the application of the above-mentioned TiO2 / MnO2 / C composite catalyst loaded on a macroscopic carrier in formaldehyde removal under different conditions.

[0014] Furthermore, the application of the above-mentioned TiO2 / MnO2 / C composite catalyst loaded on a macroscopic carrier in formaldehyde removal is realized through the following steps:

[0015] a) Put the TiO2 / MnO2 / C composite catalyst loaded on the macroscopic carrier into a steady-state reactor;

[0016] b) Introduce formaldehyde gas with a certain concentration into the above-mentioned steady-state reactor, and comprehensively evaluate the performance of the composite catalyst for formaldehyde removal under light and dark conditions. Use acetylacetone spectrophotometry and gas chromatography to detect the concentrations of formaldehyde gas and carbon dioxide gas molecules at different reaction times respectively.

[0017] Specifically, in step b), the initial concentration of formaldehyde gas is 0.1 - 500 ppm. Formalin solution can be directly used, or synthetic air (including 80% N2 and 20% O2) with a certain flow rate can be used as the carrier gas to purge the solid polyformaldehyde powder placed in a water bath environment at 30 - 40 °C to obtain formaldehyde gas with an initial concentration of 0.1 - 500 ppm. After reacting for a period of time, the formaldehyde gas is completely mineralized into non-toxic CO2 and H2O.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The method of the present invention can obtain a TiO2 / MnO2 / C composite catalyst loaded on a macroscopic carrier that can efficiently remove formaldehyde all day long, which simultaneously has the ability of photo-thermal synergistic catalytic oxidation and the ability of adsorption / catalytic oxidation synergistic effect. The presence of carbon makes formaldehyde more easily adsorbed on the catalyst, and another advantage is its light absorption and heat absorption ability, which not only improves the absorption of sunlight by the composite catalyst but also raises the surface temperature of the catalyst, enabling the rapid removal of formaldehyde under the action of photo-thermal synergistic catalytic oxidation and adsorption / catalytic oxidation synergistic effect. Since it is loaded on a macroscopic carrier, it also overcomes the problems of harsh use scenarios and difficult recovery of traditional powder catalysts. In addition, the preparation method of the present invention has a simple operation process, low raw material prices, and convenient subsequent recovery of the catalyst, which is very conducive to the actual commercial application of formaldehyde removal. Description of the Drawings

[0020] Figure 1 is a performance comparison diagram of the formaldehyde removal rates of TiO2 / MnO2 / C composite catalysts with different loadings and mass ratios prepared from titanium dioxide and potassium permanganate loaded on melamine sponge in Examples 1 to 3, as well as titanium dioxide catalyst and manganese oxide / carbon catalyst;

[0021] Figure 2 is a curve graph of the change in CO2 concentration of the MS-1.5T / 3M / C composite catalyst under light and dark conditions;

[0022] Figure 3 It is a column chart of the cyclic stability of the formaldehyde removal rate performance of the MS-1.5T / 3M / C composite catalyst under light conditions;

[0023] Figure 4 is a scanning electron microscope image (SEM) of the TiO2 / MnO2 / C composite catalyst and manganese oxide / carbon catalyst supported on melamine sponge prepared with different mass ratios of titanium dioxide and potassium permanganate in Examples 1 to 3;

[0024] Figure 5 is a powder X-ray diffractometer image (XRD) of the TiO2 / MnO2 / C composite catalyst and titanium dioxide catalyst, manganese oxide / carbon catalyst supported on melamine sponge prepared with different mass ratios of titanium dioxide and potassium permanganate in Examples 1 to 3;

[0025] Figure 6 is an infrared spectrum of the TiO2 / MnO2 / C composite catalyst and manganese oxide / carbon catalyst supported on melamine sponge prepared with different mass ratios of titanium dioxide and potassium permanganate in Example 1;

[0026] Figure 7 Figure 10 shows the specific surface area (Figure a) and pore size distribution diagram (Figure b) of the TiO2 / MnO2 / C composite catalyst and manganese oxide / carbon catalyst, titanium dioxide supported on melamine sponge prepared with different mass ratios of titanium dioxide and potassium permanganate in Example 1;

[0027] Figure 8 is an ultraviolet-visible diffuse reflectance (UV-Vis DRS) image of the TiO2 / MnO2 / C composite catalyst and titanium dioxide catalyst, manganese oxide / carbon catalyst supported on melamine sponge prepared with different mass ratios of titanium dioxide and potassium permanganate in Example 1;

[0028] Figure 9 is a graph of the removal rate of formaldehyde by the MS-1.5T / 3M / C composite catalyst under natural light irradiation;

[0029] Figure 10 is a curve of the concentration change of CO2 generated by the MS-1.5T / 3M / C composite catalyst under natural light irradiation;

[0030] Figure 11 is a comparison chart of the formaldehyde removal rate performance of the AFC-1.5T / 3M / C, MS-1.5T / 3M / Cp, and MS-1.5T / 3M / Cz composite catalysts. Detailed implementation mode

[0031] To more clearly illustrate the present invention, the following further elaborates the present invention in conjunction with the attached drawings and preferred embodiments. The following specific embodiments are better illustrations of the present invention, rather than limiting the protection scope of the present invention.

[0032] In the following embodiments, all raw materials can be directly purchased.

[0033] Example 1

[0034] By changing the masses of potassium permanganate and titanium dioxide, a TiO2 / MnO2 / C composite catalyst supported on a macroscopic carrier was prepared, which was specifically achieved through the following synthesis steps:

[0035] (1) Different masses of titanium dioxide were added to 50 ml of deionized water and stirred for 20 min, then different masses of potassium permanganate were added (the mass groups of titanium dioxide and potassium permanganate were: 0.6 g of potassium permanganate and 0.6 g of titanium dioxide, 0.3 g of potassium permanganate and 0.3 g of titanium dioxide, 0.15 g of potassium permanganate and 0.15 g of titanium dioxide, 0.3 g of potassium permanganate and 0.15 g of titanium dioxide, 0.15 g of potassium permanganate and 0.3 g of titanium dioxide, 0.225 g of potassium permanganate and 0.225 g of titanium dioxide, 0.3375 g of potassium permanganate and 0.1225 g of titanium dioxide) and stirring was continued for 10 min. After stirring ended, fructose (the mass ratio of fructose to potassium permanganate was 3:20) was added and stirred for 3 min. Finally, a circular melamine sponge with a diameter of 7 cm and a thickness of 5 mm that had been cut to size was added and ultrasonicated for 10 min. After ultrasonication ended, it was left to react in a water bath at 80 °C for 15 min. After cooling to room temperature, it was dried at 105 °C for 12 h, and thus TiO2 / MnO2 / C composite catalysts with different loadings and mass ratios (2:1, 1:2, 1:1, 3:1) supported on melamine sponges were obtained (denoted as MS-TiO2 / MnO2 / C, abbreviated as MS-xT / yM / C, for example, the one prepared from 0.15 g of titanium dioxide and 0.3 g of potassium permanganate was denoted as MS-1.5T / 3M / C). The titanium dioxide used above was commercial P25, the stirring rate was 800 rpm, and the ultrasonic frequency was 40 kHz.

[0036] The application of the above composite catalyst in the oxidative removal of formaldehyde under room temperature light conditions was achieved through the following steps:

[0037] a) The TiO2 / MnO2 / C composite catalysts with different loadings and mass ratios supported on melamine sponges prepared above were respectively placed in a steady-state reactor.

[0038] b) In the steady-state reactor, formaldehyde gas generated from paraformaldehyde in a water bath at 40 °C was purged with synthetic air until the required concentration was reached. The fan was turned on to make the concentration uniform. When the concentration reached 100 ppm, the synthetic air purge was stopped. First, dark adsorption was carried out. After dark adsorption ended, a 300W xenon lamp (light power density: 100 mW / cm 2 , similar to outdoor sunlight; wavelength range was the full solar spectrum) was used to irradiate the composite catalyst for five hours, and the results are shown in Figure 1 .

[0039] From Figure 1From the test results, it can be seen that the removal rates of formaldehyde gas by composite catalysts with different loadings and mass ratios can all reach over 74% within 5 h. Among them, when the masses of potassium permanganate and titanium dioxide are 0.3 g and 0.15 g respectively, the performance of catalytic oxidation of formaldehyde is the best, and the removal rate of formaldehyde is as high as 82.54%.

[0040] Example 2

[0041] Taking the MS-1.5T / 3M / C composite catalyst with the best performance under light conditions in Example 1 as the research object, evaluate its performance of catalytic oxidation of formaldehyde under dark conditions, and test its cyclic stability under light conditions.

[0042] The experimental process of cyclic stability test is the same as that of Example 1. The difference between the experimental process of catalytic oxidation of formaldehyde under dark conditions and Example 1 is that the MS-1.5T / 3M / C composite catalyst is completely in a dark environment throughout the process. The results are shown in Figure 1 .

[0043] From Figure 1 the test results, it can be seen that: under the condition of no light, the removal rate of formaldehyde by the MS-1.5T / 3M / C composite catalyst can still reach 78.89%. Comparing the mineralization ability of Example 1 and the MS-1.5T / 3M / C without light test above, from Figure 2 it can be seen that the amount of CO2 generated under light conditions is significantly higher than that under dark conditions. This means that compared with the mineralization ability under dark conditions, this composite catalyst has a better mineralization effect on formaldehyde under light conditions, and formaldehyde is oxidized into environmentally harmless water and carbon dioxide in large quantities. And the change amount of CO2 gas molecules is significantly higher than that of HCHO gas molecules, mainly due to the adsorption of some HCHO gas molecules on the reactor surface. In the cyclic stability test of formaldehyde removal under light conditions, the results are shown in Figure 3 , from Figure 3 it can be seen that the removal rate fluctuates little after 4 cycles, indicating that it has good stability and durability.

[0044] Example 3

[0045] Systematically compare the formaldehyde removal performance of the MS-1.5T / 3M / C composite catalyst, titanium dioxide catalyst, and manganese oxide / carbon composite catalyst. Among them, the preparation of the titanium dioxide catalyst and the manganese oxide / carbon catalyst is achieved through the following steps:

[0046] (1) Add 0.15 g of titanium dioxide to 50 ml of deionized water and stir for 20 min. After stirring, add a cut circular melamine sponge with a diameter of 7 cm and a thickness of 5 mm and ultrasonicate for 10 min. After ultrasonication, let it react in a water bath at 80 °C for 15 min. After cooling to room temperature, dry it at 105 °C for 12 h to obtain a titanium dioxide catalyst supported on a melamine sponge (denoted as MS-1.5T).

[0047] (2) Add 0.3 g of potassium permanganate to 50 ml of deionized water and stir evenly. After stirring, add fructose (the mass ratio of fructose to potassium permanganate is 3:20) and stir for 3 min. Finally, add a cut circular melamine sponge with a diameter of 7 cm and a thickness of 5 mm and ultrasonicate for 10 min. After ultrasonication, let it react in a water bath at 80 °C for 15 min. After cooling to room temperature, dry it at 105 °C for 12 h to obtain a manganese oxide / carbon catalyst supported on a melamine sponge (denoted as MS-3M / C). The titanium dioxide used above is commercial P25, the stirring rate is 800 rpm, and the ultrasonic frequency is 40 kHz.

[0048] Compare its application in removing formaldehyde under room temperature light conditions. The experimental steps are the same as those in Example 1.

[0049] Perform relevant characterizations on the TiO2 / MnO2 / C composite catalysts (i.e., MS-1.125T / 3.375M / C, MS-1.5T / 3M / C, MS-2.25T / 2.25M / C, MS-3T / 1.5M / C) with different mass ratios (1:3, 1:2, 1:1, 2:1) supported on melamine sponges and MS-3M / C successfully prepared in Example 1 and Example 3. The results are shown in Figures 4 to 8 . Observe the morphology of the catalyst by scanning electron microscopy. The results are shown in Figure 4 . It can be seen from Figure 4 that the catalyst has uniform size ( Figure 4 In, A, B, C, D, and E are MS-3M / C, MS-1.125T / 3.375M / C, MS-1.5T / 3M / C, MS-2.25T / 2.25M / C, and MS-3T / 1.5M / C respectively), and there is no obvious change in the morphology of other catalysts except MS-1.125T / 3.375M / C. It is found by X-ray diffractometry (XRD) that the MS-3M / C has the characteristic peaks of this crystal form compared with the δ-MnO2 standard card, proving that it belongs to the δ-MnO2 crystal form. MS-1.125T / 3.375M / C, MS-1.5T / 3M / C, MS-2.25T / 2.25M / C, and MS-3T / 1.5M / C contain both the characteristic peaks of δ-MnO2 and titanium dioxide (seeFigure 5 ), which proves the successful compounding. Through infrared spectroscopy tests, a large number of hydroxyl functional groups are present on the surface of all catalysts (see Figure 6 ). In terms of specific surface area and pore size distribution, the composite catalyst has a large specific surface area and a rich mesoporous structure (see Figure 7 ), which is beneficial to the absorption and diffusion of formaldehyde. Through ultraviolet-visible diffuse reflectance (UV-Vis DRS) tests, it is found that the visible light absorption of all catalysts has been greatly improved (see Figure 8 ). All the characteristics proved by the above characterizations are beneficial to the adsorption and degradation of formaldehyde.

[0050] The test results show that the formaldehyde removal performance of MS-3M / C and MS-1.5T is lower than that of the best-performing MS-1.5T / 3M / C (see Figure 1), demonstrating the advantages of the composite catalyst under light conditions.

[0051] Example 4

[0052] The TiO2 / MnO2 / C composite catalyst MS-1.5T / 3M / C with the best performance loaded on melamine sponge was tested under outdoor sunlight irradiation conditions (autumn, temperature was 10 - 20 °C during the test period), and the application of formaldehyde removal performance.

[0053] The experimental process was the same as that in Example 1, except that the experiment was carried out outdoors and sunlight was used to replace the xenon lamp for irradiation. The results are shown in detail in Figure 9 and 10 .

[0054] The test results show that the formaldehyde removal can still reach 76.5% under outdoor sunlight irradiation (see Figure 9), and formaldehyde is also continuously mineralized to produce CO2 (see Figure 10). Moreover, the change amount of CO2 gas molecules is significantly higher than that of HCHO gas molecules, mainly due to the adsorption of some HCHO gas molecules on the reactor surface. The test results indicate that the composite catalyst prepared in the present invention still has high efficiency in removing formaldehyde under natural conditions.

[0055] Example 5

[0056] A TiO2 / MnO2 / C composite catalyst loaded on activated carbon fiber cloth was prepared using activated carbon fiber cloth as the macroscopic carrier, and it was specifically realized through the following synthesis steps:

[0057] (1) Add 0.15 g of titanium dioxide to 50 ml of deionized water and stir for 20 min. Then add 0.3 g of potassium permanganate and continue stirring for 10 min. After stirring, add fructose (the mass ratio of fructose to potassium permanganate is 3:20) and stir for 3 min. Finally, add a circular activated carbon fiber cloth with a cut diameter of 6 cm and a thickness of 10 mm and ultrasonicate for 10 min. After ultrasonication, let it stand and react in a water bath at 80 °C for 15 min. After cooling to room temperature, dry it at 105 °C for 12 h to obtain the TiO2 / MnO2 / C composite catalyst loaded on the activated carbon fiber cloth (denoted as ACF-1.5T / 3M / C). The titanium dioxide used above is commercial P25, the stirring rate is 1000 rpm, and the ultrasonic frequency is 40 kHz.

[0058] Application of the composite catalyst loaded on the activated carbon fiber cloth in removing formaldehyde under room temperature light conditions. The experimental steps are the same as those in Example 1.

[0059] The test results show that the final formaldehyde removal rate of ACF-1.5T / 3M / C reaches 78.88% (see Figure 11), showing excellent formaldehyde removal performance.

[0060] Example 6

[0061] Prepare the TiO2 / MnO2 / C composite catalyst loaded on melamine sponge using glucose and sucrose as carbon sources. The specific synthesis steps are as follows:

[0062] (1) Add 0.15 g of titanium dioxide to 50 ml of deionized water and stir for 20 min. Then add 0.3 g of potassium permanganate and continue stirring for 10 min. After stirring, add 0.045 g of glucose or 0.085 g of sucrose and stir for 3 min. Finally, add a circular melamine sponge with a cut diameter of 7 cm and a thickness of 5 mm and ultrasonicate for 10 min. After ultrasonication, let it stand and react in a water bath at 80 °C for 15 min. After cooling to room temperature, dry it at 105 °C for 12 h to obtain the TiO2 / MnO2 / C composite catalyst loaded on the melamine sponge (denoted as MS-1.5T / 3M / Cp when glucose is the carbon source and MS-1.5T / 3M / Cz when sucrose is the carbon source). The titanium dioxide used above is commercial P25, the stirring rate is 1000 rpm, and the ultrasonic frequency is 40 kHz.

[0063] Application of the above-prepared catalyst in removing formaldehyde under room temperature light conditions. The experimental steps are the same as those in Example 1.

[0064] The test results show that the final formaldehyde removal rates of MS-1.5T / 3M / Cp and MS-1.5T / 3M / Cz are both higher than 70% (see Figure 11), showing good formaldehyde removal performance.

[0065] In addition, the above-described embodiments are introduced for those skilled in the art to understand, recognize, and use this invention patent. It is very easy for those skilled in the art to make various modifications or changes to the present invention, and these changes that do not depart from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A preparation method of a TiO2 / MnO2 / C composite catalyst supported on a macroscopic carrier, characterized in that, Including the following steps: Add titanium dioxide to deionized water, stir, add potassium permanganate, and continue stirring; add a carbon source, stir evenly and then add a macro carrier, and perform ultrasonic mixing. React under water bath conditions. After the reaction is completed, cool and dry to obtain a TiO2 / MnO2 / C composite catalyst supported on the macro carrier; the mass ratio of titanium dioxide to potassium permanganate is (1~4):(1~4); the carbon source is one or more of glucose, fructose, glycogen, cellulose, and sucrose, and the macro carrier is one of melamine sponge and activated carbon fiber cloth; the mass ratio of potassium permanganate to the carbon source is 20:(1~6); the mass-volume ratio of titanium dioxide to the macro carrier is (0.15~0.6) g:(15~30) cm 3 ; the water bath temperature is 80~100 °C, and the water bath time is 10~20 min; the drying temperature is 60~105 °C, and the drying time is 6~12 h; the titanium dioxide is P25. The TiO2 / MnO2 / C composite catalyst supported on a macroscopic support prepared by the method according to claim 1.

3. Use of the TiO2 / MnO2 / C composite catalyst carried on the macroscopic carrier according to claim 2 in the removal of formaldehyde, characterized in that, Under one or more of the following conditions: a) The initial concentration of formaldehyde is 0.1 - 500 ppm; b) In the presence or absence of light; c) -5°C ≤ environmental temperature ≤ 100°C.

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