Vehicle-mounted formaldehyde removal agent and preparation method thereof

Abstract

The invention relates to the technical field of catalysts, and discloses a vehicle-mounted formaldehyde removal agent and a preparation method thereof.The vehicle-mounted formaldehyde removal agent is obtained by doping rare earth La into a cobalt salt solution, adjusting the solid-to-liquid ratio of reactants, washing and drying a product after hydro-thermal synthesis is finished, obtaining a rare earth La-doped rare earth element Co3O4 material, then loading mesoporous MnO2, and conducting roasting treatment; the microwave-hydrothermal method can enable the salt solution to be uniformly heated in a short time, and the influence of temperature gradient is greatly eliminated, so that uniform superfine powder is obtained; the vehicle-mounted formaldehyde removal agent shows long-term and efficient performance in the formaldehyde removal process, the activity of the vehicle-mounted formaldehyde removal agent is still kept to be 90% or above even if the vehicle-mounted formaldehyde removal agent reacts for a long time, the activity of the vehicle-mounted formaldehyde removal agent is not obviously reduced after the vehicle-mounted formaldehyde removal agent continuously reacts for 8 h, and the vehicle-mounted formaldehyde removal agent has good activity and stability; the catalyst can replace a traditional noble metal catalyst, and is low in cost, simple in preparation process, free of emission of three wastes, safe and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, in particular to a vehicle-mounted formaldehyde removal agent and a preparation method thereof. Background Art

[0002] Formaldehyde is a relatively common and highly toxic harmful substance that can cause serious impacts on human health, including irritation to the eyes, nose and throat, headaches, nausea and other symptoms. Long-term exposure may even lead to more serious health problems. However, formaldehyde is everywhere. Wherever adhesives are used in large quantities, formaldehyde will always be released. Most synthetic carpets and paints also contain a certain amount of formaldehyde. There is often residual formaldehyde gas inside new cars, mainly from vehicle interior materials, seats, floor mats, adhesives, etc. These materials used in the manufacturing and assembly process of new cars will release formaldehyde, posing a potential threat to the health of drivers and passengers. The use of on-board formaldehyde removers can effectively reduce the concentration of these harmful gases and provide a healthier in-car environment.

[0003] The interior of today's cars is closed for a long time and the temperature is suitable, which makes it difficult to discharge harmful gases such as formaldehyde and causes a large number of bacteria and viruses to breed, seriously endangering human health. At present, there are adsorption technology, photocatalytic degradation technology, low-temperature catalytic oxidation technology, etc. to remove formaldehyde in cars. Adsorption technology mainly uses materials with high specific surface area such as activated carbon and molecular sieves to adsorb formaldehyde, but the adsorption capacity of adsorption materials is very limited, and they need to be regenerated or replaced regularly, and they are prone to secondary pollution. Photocatalytic degradation technology mainly uses nano-TiO2 as a photocatalyst, which can decompose formaldehyde at room temperature through the action of active hydroxyl free radicals and superoxide free radicals. This technology has good application prospects, but the photocatalytic reaction currently requires ultraviolet excitation light source, and the utilization efficiency of visible light is extremely low. In addition, there are problems such as catalyst deactivation.

[0004] Catalytic oxidation technology can completely oxidize formaldehyde into non-toxic and harmless H2O and CO2 at a relatively low temperature, thus becoming the most promising method for removing formaldehyde. Patent CN108187688A discloses a method for preparing a catalyst that can completely catalytically oxidize formaldehyde at room temperature. Both of them also show a high removal efficiency in formaldehyde purification. However, although precious metal catalysts have good formaldehyde removal effects, they are too expensive and difficult to industrialize. Cheap transition metal catalysts usually have low catalytic activity at low temperatures, are easily deactivated, and take a long time to remove formaldehyde. Therefore, seeking cheap, long-lasting, and fast vehicle-mounted formaldehyde removers to replace traditional precious metal catalysts and promote their application has become a recent research hotspot. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a vehicle-mounted formaldehyde remover and a preparation method thereof, which has a high formaldehyde removal rate at room temperature, can replace traditional precious metal catalysts, greatly reduce manufacturing costs, and improve market competitiveness.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing a vehicle-mounted formaldehyde removal agent is carried out according to the following steps: Step (1), under a nitrogen atmosphere, add cobalt salt, La(NO3)3 and deionized water to a reaction bottle, stir to dissolve, add NH4HCO3, adjust the pH of the mixed solution to 7-9 with sodium hydroxide, place the reaction bottle in a microwave reaction vessel, perform microwave irradiation reaction, filter, wash with deionized water, grind and sieve, and then sinter in a high-temperature furnace, raise the temperature of the high-temperature furnace to 700-800°C at a rate of 2-5°C / min, keep warm for 3-6h, and cool with the furnace to obtain rare earth La-doped Co3O4 material; Step (2), dissolving the rare earth La doped Co3O4 material in deionized water, adding mesoporous MnO2, stirring at room temperature at a rotation speed of 500-800 r / min for 1-2 hours, drying and calcining, and crushing and sieving after cooling to obtain a vehicle-mounted formaldehyde remover.

[0007] Preferably, the cobalt salt in step (1) is any one of Co(NO3)2, CoSO4, and CoCl2.

[0008] Preferably, in step (1), the ratio of cobalt salt, La(NO3)3, and NH4HCO3 is (0.7-0.99) mol: (0.01-0.30) mol: (2.1-2.5) mol.

[0009] Preferably, the microwave power of the microwave irradiation reaction in step (1) is 120-150 W, the temperature is 140-160° C., and the time is 2-4 h.

[0010] Preferably, in step (2), the ratio of rare earth La-doped Co3O4 material to mesoporous MnO2 is 100g:0.5g.

[0011] Preferably, in step (2), the calcination temperature is 300-700° C., and the calcination time is 0.5-8 h.

[0012] Preferably, the preparation method of mesoporous MnO2 in step (2) is carried out according to the following steps: add template SBA-15 and deionized water to a reaction flask, stir evenly, add Mn(NO3)2, stir at room temperature for 2-5 hours, place in a muffle furnace after drying, calcine at 350-450°C for 5-10 hours, add to sodium hydroxide aqueous solution after cooling, heat and boil for 10-20 minutes, filter and wash until neutral, and obtain mesoporous MnO2 after drying.

[0013] Preferably, the ratio of template SBA-15 to Mn(NO3)2 is 1g:(2-3)g.

[0014] Preferably, the mass fraction of the sodium hydroxide aqueous solution is 15-25%.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) Mesoporous MnO2 has a layered structure with three-dimensional pores, and the pore size is between micropores and macropores. The active sites on its surface can activate oxygen and water molecules in the air to produce active oxygen (such as oxygen free radicals, oxygen anions, etc.), which can react with formaldehyde and decompose it into carbon dioxide and water. The mesoporous structure provides MnO2 with a larger specific surface area, which increases the contact area between the catalyst and formaldehyde. It has certain moisture resistance, excellent ion exchangeability and good redox properties. In addition, it also has excellent pore effect and adsorption effect, which enables many formaldehyde adsorption and decomposition processes to be realized in the pores. It not only has high catalytic efficiency and good activity, but is also easy to recycle and reuse, and has great environmental catalytic potential.

[0016] (2) The doping of rare earth La can change the surface properties of Co3O4 materials and increase the active sites on the surface of Co3O4. Formaldehyde molecules can contact the surface of Co3O4 modified by rare earth La through van der Waals force or chemical bond formation, thereby improving its adsorption capacity for formaldehyde molecules. At the same time, rare earth La-doped Co3O4 materials have the ability of redox cycling, that is, during the catalytic process, their valence state can change, thereby continuously catalyzing the oxidation of formaldehyde.

[0017] (3) The microwave-hydrothermal method can make the salt solution be heated uniformly in a short time, greatly eliminating the influence of temperature gradient, thereby obtaining uniform ultrafine powder; the vehicle-mounted formaldehyde remover of the present invention shows long-term and high-efficiency performance in the process of removing low-concentration formaldehyde, and the activity is still maintained above 90% even after a long reaction time. The activity does not decrease significantly after continuous reaction for 8 hours, and has good activity and stability; the formaldehyde remover of the present invention can be firmly fixed on various media to play the role of formaldehyde removal, replacing traditional precious metal catalysts, with low cost, simple preparation process, no "three wastes" emission, and safety and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The formaldehyde removal rate of Examples 1-5 and Comparative Example 1 was tested.

[0019] Figure 2 This is the test of formaldehyde removal rate in Examples 6-10.

[0020] Figure 3 It is a stability test for formaldehyde removal at room temperature. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Unless otherwise specified, the raw materials and reagents used in this application are commercially available or can be prepared by known methods.

[0023] Preparation method of template SBA-15: Take 4g of triblock copolymer P123, add it to 130mL of deionized water, then add 20mL of concentrated hydrochloric acid, mix well, put it in a 40℃ constant temperature water bath and stir for 4h until the solution is clear and transparent, add 8.8g of tetraethyl orthosilicate dropwise to the solution, continue stirring for 20h, transfer all the reactants to an 80mL high-pressure reactor, place it in a 120℃ oven, take it out after hydrothermal crystallization for 48h, take it out after natural cooling, take out the reactant, filter it, wash it with distilled water and anhydrous ethanol several times, dry it at 110℃ for 8h, and then place it in a muffle furnace and calcine it at 550℃ for 6h to obtain the template SBA-15.

[0024] Example 1

[0025] Under a nitrogen atmosphere, 9.9 mmol of Co(NO3)2, 0.1 mmol of La(NO3)3 and 50 mL of deionized water were added to the reaction bottle, stirred to dissolve, 23 mmol of NH4HCO3 was added, and the pH of the mixed solution was adjusted to 8 with sodium hydroxide. The reaction bottle was placed in a microwave reaction vessel, and microwaved at 140 W and 150°C for 3 h. The product was filtered, washed with deionized water, ground and sieved, and then sintered in a high-temperature furnace. The high-temperature furnace was raised to 750°C at a rate of 3°C / min, kept warm for 5 h, and cooled with the furnace to obtain rare earth La-doped Co3O4 material.

[0026] Example 2

[0027] Under a nitrogen atmosphere, 9.8 mmol of CoSO4, 0.2 mmol of La(NO3)3 and 50 mL of deionized water were added to the reaction bottle, stirred to dissolve, 21 mmol of NH4HCO3 was added, and the pH of the mixed solution was adjusted to 7 with sodium hydroxide. The reaction bottle was placed in a microwave reaction vessel, and microwaved at 150 W and 160 ° C for 2 h. The product was filtered, washed with deionized water, ground and sieved, and then sintered in a high-temperature furnace. The high-temperature furnace was raised to 800 ° C at a rate of 5 ° C / min, kept warm for 3 h, and cooled with the furnace to obtain rare earth La doped Co3O4 material.

[0028] Example 3

[0029] Under a nitrogen atmosphere, add 9.5 mmol of CoCl2, 0.5 mmol of La(NO3)3 and 50 mL of deionized water to the reaction bottle, stir to dissolve, add 25 mmol of NH4HCO3, adjust the pH of the mixed solution to 9 with sodium hydroxide, place the reaction bottle in a microwave reaction vessel, irradiate with microwaves at 120 W and 140 ° C for 4 h, filter, wash with deionized water, grind and sieve, and then sinter in a high-temperature furnace. The high-temperature furnace is raised to 700 ° C at a rate of 2 ° C / min, kept warm for 6 h, and cooled with the furnace to obtain rare earth La doped Co3O4 material.

[0030] Example 4

[0031] Under a nitrogen atmosphere, add 9 mmol of Co(NO3)2, 1 mmol of La(NO3)3 and 50 mL of deionized water to the reaction bottle, stir to dissolve, add 24 mmol of NH4HCO3, adjust the pH of the mixed solution to 8.5 with sodium hydroxide, place the reaction bottle in a microwave reaction vessel, irradiate with microwaves at 145 W and 150°C for 3 h, filter, wash with deionized water, grind and sieve, and then sinter in a high-temperature furnace. The high-temperature furnace is raised to 780°C at a rate of 4°C / min, kept warm for 4 h, and cooled with the furnace to obtain rare earth La-doped Co3O4 material.

[0032] Example 5

[0033] Under a nitrogen atmosphere, add 7 mmol of CoCl2, 3 mmol of La(NO3)3 and 50 mL of deionized water to the reaction bottle, stir to dissolve, add 22.5 mmol of NH4HCO3, adjust the pH of the mixed solution to 8 with sodium hydroxide, place the reaction bottle in a microwave reaction vessel, irradiate with microwaves at 150 W and 150°C for 4 h, filter, wash with deionized water, grind and sieve, and then sinter in a high-temperature furnace. The high-temperature furnace is raised to 720°C at a rate of 3°C / min, kept warm for 5 h, and cooled with the furnace to obtain rare earth La-doped Co3O4 material.

[0034] Comparative Example 1 Under a nitrogen atmosphere, add 10 mmol of Co(NO3)2 and 50 mL of deionized water to the reaction bottle, stir to dissolve, add 23 mmol of NH4HCO3, adjust the pH of the mixed solution to 8 with sodium hydroxide, place the reaction bottle in a microwave reaction vessel, irradiate with microwaves at 140 W and 150 ° C for 3 h, filter, wash with deionized water, grind and sieve, and then sinter in a high-temperature furnace. The high-temperature furnace is raised to 750 ° C at a rate of 3 ° C / min, kept warm for 5 h, and cooled with the furnace to obtain Co3O4 material.

[0035] Formaldehyde removal rate test: weigh 0.15g of the Co3O4 materials prepared in Examples 1-5 and Comparative Example 1, pretreat them at 150°C for 1h in an air atmosphere, and then load them into a glass reaction tube with an inner diameter of 6mm; the experimental conditions are: gas flow rate, 1L / min; reaction temperature, room temperature (35°C); air humidity, 50%-60%, the residence time of the air flow through the reaction chamber is expressed by the gas space velocity (GHSV, which refers to the intake air flow rate of the catalyst treatment per unit mass or volume). The gas space velocity in this experiment is 6000mL / (g·h), and a formaldehyde detector is used to test the inlet formaldehyde concentration C0 (ppm) and the outlet formaldehyde concentration C1 (ppm), and each time is repeated 3 times to take the average value.

[0036] Formaldehyde removal rate (%) = (C0-C1) / C0×100%.

[0037] From the attached Figure 1 It can be seen that the catalytic formaldehyde oxidation activity of pure Co3O4 in Comparative Example 1 is relatively low, with an initial activity of 65%, which drops to about 30% after 8 hours of reaction; when the rare earth content is between 2% and 5%, the initial activity is increased to more than 85%, and the activity decreases after 8 hours of reaction, but the activity is still higher than 60%; when the rare earth content is higher than 5%, the activity slowly decreases with the increase of the rare earth content. When the rare earth content is increased to 30%, its activity is equivalent to that of unmodified Co3O4. The main reason for the slow decrease in the activity of the Co-based catalyst with the extension of reaction time may be the high humidity of the reaction gas, and the water resistance of the Co-based catalyst is general, and water molecules are adsorbed on the active sites, resulting in catalyst deactivation.

[0038] Example 6

[0039] (1) Add 10 g of template SBA-15 and 180 mL of deionized water to a reaction flask, stir evenly, then add 25 g of Mn(NO3)2, stir at room temperature for 4 h, dry and place in a muffle furnace, calcine at 400 °C for 8 h, cool and add to a 20% sodium hydroxide aqueous solution, heat and boil for 15 min, filter and wash until neutral, and dry to obtain mesoporous MnO2.

[0040] (2) Dissolve 100 g of rare earth La-doped Co3O4 material (prepared in Example 3) in deionized water, add 0.5 g of mesoporous MnO2, stir at room temperature for 1 h at a rotation speed of 650 r / min, dry and calcine at 300°C for 0.5 to 8 h, crush and sieve after cooling to obtain a vehicle-mounted formaldehyde remover.

[0041] Example 7

[0042] (1) Add 10 g of template SBA-15 and 180 mL of deionized water to a reaction flask, stir evenly, then add 20 g of Mn(NO3)2, stir at room temperature for 2 h, dry and place in a muffle furnace, calcine at 450 °C for 5 h, cool and add to a 15% sodium hydroxide aqueous solution, heat and boil for 10 min, filter and wash until neutral, and dry to obtain mesoporous MnO2.

[0043] (2) Dissolve 100 g of rare earth La-doped Co3O4 material (prepared in Example 3) in deionized water, add 0.5 g of mesoporous MnO2, stir at room temperature at a speed of 800 r / min for 1 h, dry and calcine at 400°C for 0.5 to 8 h, crush and sieve after cooling to obtain a vehicle-mounted formaldehyde remover.

[0044] Example 8

[0045] (1) Add 10 g of template SBA-15 and 180 mL of deionized water to a reaction flask, stir evenly, then add 30 g of Mn(NO3)2, stir at room temperature for 5 h, dry and place in a muffle furnace, calcine at 350 °C for 10 h, cool and add to a 25% sodium hydroxide aqueous solution, heat and boil for 20 min, filter and wash until neutral, and dry to obtain mesoporous MnO2.

[0046] (2) Dissolve 100 g of rare earth La-doped Co3O4 material (prepared in Example 3) in deionized water, add 0.5 g of mesoporous MnO2, stir at room temperature for 2 h at a rotation speed of 500 r / min, dry and calcine at 500 °C for 0.5 to 8 h, crush and sieve after cooling to obtain a vehicle-mounted formaldehyde remover.

[0047] Example 9

[0048] (1) Add 10 g of template SBA-15 and 180 mL of deionized water to a reaction flask, stir evenly, then add 26 g of Mn(NO3)2, stir at room temperature for 3 h, dry and place in a muffle furnace, calcine at 420 °C for 7 h, cool and add to 18% sodium hydroxide aqueous solution, heat and boil for 12 min, filter and wash until neutral, and dry to obtain mesoporous MnO2.

[0049] (2) Dissolve 100 g of rare earth La-doped Co3O4 material (prepared in Example 3) in deionized water, add 0.5 g of mesoporous MnO2, stir at room temperature for 2 h at a rotation speed of 750 r / min, dry and calcine at 600 °C for 0.5 to 8 h, crush and sieve after cooling to obtain a vehicle-mounted formaldehyde remover.

[0050] Example 10

[0051] (1) Add 10 g of template SBA-15 and 180 mL of deionized water to a reaction flask, stir evenly, then add 22 g of Mn(NO3)2, stir at room temperature for 4 h, dry and place in a muffle furnace, calcine at 380 °C for 10 h, cool and add to a 22% sodium hydroxide aqueous solution, heat and boil for 18 min, filter and wash until neutral, and dry to obtain mesoporous MnO2.

[0052] (2) Dissolve 100 g of rare earth La-doped Co3O4 material (prepared in Example 3) in deionized water, add 0.5 g of mesoporous MnO2, stir at room temperature for 2 h at a rotation speed of 750 r / min, dry and calcine at 700 °C for 0.5 to 8 h, crush and sieve after cooling to obtain a vehicle-mounted formaldehyde remover.

[0053] Formaldehyde removal rate test: weigh 0.15g of each of the vehicle-mounted formaldehyde removers prepared in Examples 6-10, pretreat at 150°C for 1h in an air atmosphere, and then load them into a glass reaction tube with an inner diameter of 6mm; the experimental conditions are: gas flow rate, 1L / min; reaction temperature, room temperature (35°C); initial formaldehyde concentration of about 1.0mg / ml; air humidity, 50%-60%, the residence time of the air flow through the reaction chamber is expressed by the gas space velocity (GHSV, which refers to the intake air flow rate of the catalyst treatment per unit mass or volume). The gas space velocity in this experiment is 6000mL / (g·h), and a formaldehyde detector is used to test the inlet formaldehyde concentration C0 (ppm) and the outlet formaldehyde concentration C1 (ppm), each time repeated 3 times, and the average value is taken.

[0054] Formaldehyde removal rate (%) = (C0-C1) / C0×100%.

[0055] By the attached Figure 2It can be seen that the vehicle-mounted formaldehyde removal agent calcined at 300-500℃ has an activity of more than 90% after 8 hours of reaction, with no obvious downward trend, while the formaldehyde conversion rate of the vehicle-mounted formaldehyde removal agent calcined at 600℃ or 700℃ is less than 60% after 8 hours of reaction, and the activity continues to decline with the extension of reaction time. This shows that the catalyst has good catalytic performance when calcined between 300-500℃, and may achieve the goal of completely removing formaldehyde at room temperature, so it is possible to replace the commonly used precious metal-loaded catalysts on the market, greatly reduce the manufacturing cost of catalysts and finished instruments, and improve market competitiveness.

[0056] The rare earth La-doped Co3O4 material prepared in Example 3 and the vehicle-mounted formaldehyde removal agent prepared in Example 8 were tested for formaldehyde removal. Figure 3 It can be seen that the catalytic formaldehyde oxidation conversion rate at room temperature can reach 85%, and the activity does not decrease significantly after continuous reaction for 8 hours, showing good activity and stability.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a vehicle-mounted formaldehyde removal agent, characterized in that: The preparation method is carried out according to the following steps: Step (1), under a nitrogen atmosphere, add cobalt salt, La(NO3)3 and deionized water to a reaction bottle, stir to dissolve, add NH4HCO3, adjust the pH of the mixed solution to 7-9 with sodium hydroxide, place the reaction bottle in a microwave reaction vessel, perform microwave irradiation reaction, filter, wash with deionized water, grind and sieve, and then sinter in a high-temperature furnace, raise the temperature of the high-temperature furnace to 700-800°C at a rate of 2-5°C / min, keep warm for 3-6h, and cool with the furnace to obtain rare earth La-doped Co3O4 material; Step (2), dissolving the rare earth La doped Co3O4 material in deionized water, adding mesoporous MnO2, stirring at room temperature at a rotation speed of 500-800 r / min for 1-2 hours, drying and calcining, and crushing and sieving after cooling to obtain a vehicle-mounted formaldehyde remover.

2. The method for preparing the vehicle-mounted formaldehyde removal agent according to claim 1, characterized in that: The cobalt salt in step (1) is any one of Co(NO3)2, CoSO4, and CoCl2.

3. The method for preparing the vehicle-mounted formaldehyde removal agent according to claim 1, characterized in that: In the step (1), the ratio of cobalt salt, La(NO3)3 and NH4HCO3 is (0.7-0.99) mol: (0.01-0.30) mol: (2.1-2.5) mol.

4. The method for preparing the vehicle-mounted formaldehyde removal agent according to claim 1, characterized in that: The microwave power of the microwave irradiation reaction in step (1) is 120-150W, the temperature is 140-160°C, and the time is 2-4h.

5. The method for preparing the vehicle-mounted formaldehyde removal agent according to claim 1, characterized in that: In the step (2), the ratio of rare earth La-doped Co3O4 material to mesoporous MnO2 is 100g:0.5g.

6. The method for preparing the vehicle-mounted formaldehyde removal agent according to claim 1, characterized in that: In the step (2), the calcination temperature is 300-700° C. and the calcination time is 0.5-8 h.

7. The method for preparing the vehicle-mounted formaldehyde removal agent according to claim 1, characterized in that: The preparation method of mesoporous MnO2 in step (2) is carried out according to the following steps: add template SBA-15 and deionized water into a reaction flask, stir evenly, add Mn(NO3)2, stir at room temperature for 2-5 hours, place in a muffle furnace after drying, calcine at 350-450°C for 5-10 hours, add to sodium hydroxide aqueous solution after cooling, heat and boil for 10-20 minutes, filter and wash until neutral, and dry to obtain mesoporous MnO2.

8. The method for preparing the vehicle-mounted formaldehyde removal agent according to claim 7, characterized in that: The ratio of the template SBA-15 to Mn(NO3)2 is 1g:(2-3)g.

9. The method for preparing the vehicle-mounted formaldehyde removal agent according to claim 7, characterized in that: The mass fraction of the sodium hydroxide aqueous solution is 15-25%.

10. A vehicle-mounted formaldehyde removal agent, characterized in that: Obtained by the preparation method according to any one of claims 1 to 9.

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