A method of loading manganese on a hydrophilic carrier material

Abstract

The application discloses a method for loading manganese on a hydrophilic carrier material, and belongs to the technical field of formaldehyde removal. The modified catalyst is obtained by loading manganese on the hydrophilic carrier material, the inexpensive metal-based oxide is used to rapidly and efficiently degrade formaldehyde at room temperature, the preparation cost of the catalyst is greatly reduced by avoiding long-time loading production and using raw materials containing noble metals, the demand for the cost of the catalyst in actual application links is met, and the method has the characteristics of simple steps, mild conditions, short reaction period and high carrier applicability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of formaldehyde removal, and particularly relates to a method for loading manganese on a hydrophilic carrier material. BACKGROUND

[0002] In view of various hazards caused by indoor formaldehyde pollution, the World Health Organization (WHO) stipulates that the indoor formaldehyde concentration should not exceed 0.10 mg / m 3 3 , and subsequently further limits the indoor air formaldehyde concentration of civil buildings to 0.08 mg / m 3 in GB 50325-2020 “Standard for Indoor Environmental Pollution Control of Civil Building Engineering”. A type of building below requires that the formaldehyde concentration should be lower than 0.07 mg / m 3 .

[0003] In addition, according to the investigation on the excessive formaldehyde of domestic buildings, the formaldehyde excessive rate is as high as 95% within 1 year after the completion of house decoration, 83% within 2 years, and 74% within 3 years. The long-term continuous release of formaldehyde is extremely harmful to the health of residents. According to medical research, the human body will produce dizziness, headache, fatigue and other discomfort symptoms after continuously inhaling formaldehyde (>0.05 mg / m 3 ), and the skin will produce allergic dermatitis, color spots and other symptoms after excessive contact with formaldehyde, and in severe cases, it will cause respiratory difficulty, nerve disorder, induce tumor, and even death.

[0004] At present, the common formaldehyde removal methods on the market mainly include fresh air ventilation method, plant absorption method, plasma method and catalytic oxidation method. Among them, the catalytic oxidation technology has high research value due to its high efficient and green formaldehyde decomposition rate and wide application range.

[0005] However, most of the existing catalytic oxidation formaldehyde removal technologies have complex preparation processes, industrialization difficulties, long production cycle and high cost, which restrict the popularization and application of catalytic oxidation technology. For example, the photocatalyst is still mainly in powder form, and needs to use ultraviolet lamp (UV) as a medium, which has high production cost and structural requirement, and is difficult to be coupled with air purifiers.

[0006] The prior art CN114588892A discloses a preparation method of formaldehyde removal material, but in the preparation method, the loading process has a long cycle, the industrial production efficiency is low, and the equipment needs to be continuously operated, which is not conducive to the actual industrial production, and the catalyst has a high powder loss rate, which limits its application range and is not conducive to the promotion to the consumer market. In addition, the carrier of this method is limited to an anodized aluminum mesh, and the carrier has great limitations. SUMMARY​

[0007] To solve the above technical problems, the present application provides a method for loading manganese on a hydrophilic carrier material, which can quickly produce a modified catalyst for formaldehyde removal, has the characteristics of simple steps, mild conditions, short reaction period, and high applicability of the carrier. The present application uses inexpensive metal-based oxides to rapidly and efficiently degrade formaldehyde at room temperature, significantly reducing the cost of catalyst preparation by avoiding long-term loading production and using raw materials containing noble metals, meeting the demand for catalyst cost in practical application links.

[0008] To achieve the above-mentioned purpose, the present application provides a method for loading manganese on a hydrophilic carrier material, comprising the following steps:

[0009] In the mixed solution of neutral silica sol, water and titanium dioxide, ammonium polyacrylate is added, stirred uniformly, then water is added, and continues to be stirred uniformly, then sprayed on the surface of the hydrophilic carrier material, after the surface of the hydrophilic carrier material is completely changed to white, drying is carried out, to obtain a titanium-loaded hydrophilic carrier material;

[0010] The titanium-loaded hydrophilic carrier material is placed in a potassium permanganate solution and fully soaked, then removed, a mixed solution of manganese salt and potassium salt, or manganese salt and sodium salt is sprayed on the surface of the titanium-loaded hydrophilic carrier material, the spraying angle is kept as an acute angle, after the purple red color on the surface of the titanium-loaded hydrophilic carrier material is completely changed to brown black, washing, repeating the spraying and washing, and drying.

[0011] The principle of the present application is:

[0012] The present application uses a method of gluing to load titanium, without the need for chemical reaction, directly mixing titanium dioxide with adhesives and the like, and then spraying and adhering on the surface of the carrier to complete the modification. First loading titanium on the surface of the hydrophilic material and then loading manganese can improve the loading amount and dispersion of manganese, and further improve the de-aldehyde efficiency of the catalyst. Loading titanium alone does not have de-aldehyde effect. The in-situ synthesis method is used to load manganese on the surface of the titanium-loaded hydrophilic material, and a rapid reaction occurs directly on the surface of the carrier. After the active component fully soaks the carrier, the surface interaction between water molecules and the hydrophilic carrier material, the porous interface bonding strength of the hydrophilic carrier material is large, and the surface molecules or atoms have residual surface energy due to the unbalanced force. When the active component contacts the surface of the hydrophilic carrier material, it is attracted by these unbalanced forces and stays on the surface of the carrier, and a chemical reaction occurs rapidly on the surface, forming a binding force with the surface of the carrier, and completing the loading.

[0013] Compared with the previous patent CN114588892A, both manganese and titanium are loaded by redox deposition method, through long-term slow reaction, the active component is continuously deposited on the carrier, the present application greatly shortens the preparation time, and at the same time improves the activity of the modified catalyst.

[0014] Further, the hydrophilic carrier material is γ-Al2O3 / Al carrier, alumina ball, honeycomb aluminum, punched aluminum plate, carbon cloth, HEPA net or activated carbon filter cotton.

[0015] Further, the preparation method of the γ-Al2O3 / Al carrier is as follows: after the anodized aluminum substrate is calcined, porous anodic aluminum oxide (AAO) is obtained; through a thermal hydration reaction, boehmite (AlOOH) rich in hydroxyl groups is obtained; through secondary calcination, a γ-Al2O3 / Al carrier with a dense and ordered porous structure is obtained.

[0016] Further, the anodized aluminum substrate needs to be pretreated before use, and the pretreatment method is as follows: the aluminum substrate is pretreated with 5-15wt% NaOH solution and 5-15wt% HNO3 solution for 1-5min, respectively.

[0017] Further, the anodization conditions can be carried out by any one of the following methods:

[0018] Scheme A: the electrolyte is 1-5mol / L sulfuric acid solution, the temperature is 3-15℃, the oxidation voltage is 10-30V, and the electrolysis time is 2-12h.

[0019] Scheme B: the electrolyte is 0.1-0.8mol / L oxalic acid solution, the temperature is 20℃, the current density is 25A / m 2 , and the electrolysis time is 8-16h.

[0020] Further, the oxidation modes in schemes A and B are constant voltage gradient oxidation and constant current oxidation, respectively.

[0021] Further, in the preparation method of the γ-Al2O3 / Al carrier, the calcination temperature is 200-600℃, and the time is 1-3h; the thermal hydration reaction temperature is 30-95℃, and the time is 1-2h; the secondary calcination temperature is 300-600℃, and the time is 3-6h.

[0022] Further, the manganese salt is manganese sulfate, manganese chloride or manganese nitrate;

[0023] The potassium salt is potassium sulfate or potassium chloride;

[0024] The sodium salt is sodium sulfate or sodium chloride.

[0025] The application takes a hydrophilic material as a carrier, for example, reticular gamma-Al2O3 / Al (prepared by anodic oxidation technology), punched gamma-Al2O3 / Al (prepared by anodic oxidation technology), spherical alumina, honeycomb aluminum, columnar activated carbon, carbon cloth, activated carbon filter cotton or HEPA net, etc., and takes a non-noble metal as a main load; wherein the non-noble metal is preferably manganese potassium, manganese sodium, titanium manganese potassium or titanium manganese sodium mixture. The gamma-Al2O3 / Al carrier has a reticular structure, has the advantages of low pressure drop, easy shaping, light and thin volume and combination with an air purifier compared with other granular or powdered carriers.

[0026] Further, the temperature of the infiltration is 20-100℃, and the time is 10-60min.

[0027] Further, the spraying pressure is 1-2.5Mpa.

[0028] Further, the mass ratio of the neutral silicon sol, water and titanium dioxide is 5:2:2.

[0029] The ammonium polyacrylate accounts for 1wt% of the mass of the titanium dioxide.

[0030] Further, the neutral silicon sol is a 20-30wt% nanometer silicon dioxide dispersion in water, and pH=7.

[0031] Further, after the addition of the ammonium polyacrylate, the stirring temperature is 25-40℃, and the time is 1-3h.

[0032] The continued stirring time after the addition of the water is 1-3h, and the water accounts for 3-5wt% of the total mass.

[0033] Further, the method for loading manganese on the hydrophilic carrier material comprises the following steps:

[0034] The mass ratio of the neutral silicon sol, deionized water and titanium dioxide in the mixed solution is 5:2:2, 1wt% of the mass of the titanium dioxide is added to the ammonium polyacrylate, 3-5wt% of the total mass is added to the deionized water after the continuous stirring at 25-40℃ for 1-3h, so as to further improve the dispersion; the stirring is continued for 1-3h, then the hydrophilic carrier material surface is sprayed, after the hydrophilic carrier material surface is completely changed to white, drying is carried out at 120-200℃ for 1-2h, and the hydrophilic carrier material loaded with titanium is obtained;

[0035] Put the titanium-loaded hydrophilic carrier material in a potassium permanganate solution, stir at 20-100℃ for 10min-60min to fully soak it; take it out, lay it flat, and spray a mixed solution of manganese sulfate and potassium sulfate on the surface of the titanium-loaded hydrophilic carrier material after atomizing it into small particle size droplets of 0.3mm-1mm in a pressure spray gun, the spray angle is kept acute, the spray pressure is 1-2.5Mpa, after the purple red color on the surface of the titanium-loaded hydrophilic carrier material is completely changed to brown black, rinse, repeat the spraying for 4-12 rounds, and then dry naturally or dry at 20-120℃ for 1-8h.

[0036] The present application shortens the preparation time of the modified catalyst by improving the loading method, and reduces the required temperature and drug cost when loading the active component, that is, the modified catalyst can be successfully prepared.

[0037] The traditional spraying is to spray the prepared catalyst powder combined with an adhesive onto the surface of the catalyst carrier, which needs to be separately synthesized in advance and cannot be prepared in one step. The method of the present application is to adsorb a certain solution on the surface of the carrier by the hydrophilicity of the carrier itself, and then spray a reaction solution on the surface, so that the reaction occurs rapidly on the surface of the carrier to achieve the effect of one-step direct loading.

[0038] The present application has a wider range of applications and is suitable for a variety of carriers, and hydrophilic materials can be used (γ-Al2O3 / Al, spherical alumina, honeycomb aluminum, columnar activated carbon, carbon cloth, activated carbon filter cotton or HEPA, etc.).

[0039] The modified catalyst obtained by the present application has more improved activity than the previous patent (CN114588892A), and the national standard value can be reached in only 25min (the previous patent needs >40min), and the CADR value of formaldehyde is related to the degradation speed.

[0040] Further, the concentrations of the potassium permanganate solution, the manganese sulfate solution and the potassium sulfate solution are 0.1-0.3mol / L, 0.1-0.6mol / L and 0.025-0.1mol / L, respectively, and preferably the concentrations of the potassium permanganate solution, the manganese sulfate solution and the potassium sulfate solution are 0.2mol / L, 0.5mol / L and 0.05mol / L, respectively.

[0041] Further, the manganese sulfate can be replaced by manganese chloride or manganese nitrate; and the potassium sulfate can be replaced by potassium chloride, sodium sulfate or sodium chloride.

[0042] Further, the size of the titanium dioxide particles is 5nm-1μm.

[0043] A modified catalyst obtained by the above loading method.

[0044] Application of the modified catalyst in formaldehyde removal.

[0045] Compared with the prior art, the present application has the following advantages and technical effects:

[0046] (1) The present application has low requirements for the carrier, and can be widely used in various air purification filter materials.

[0047] (2) When the carrier is a structured integrated gamma-Al2O3 / Al with stable properties, sulfuric acid is used as an electrolyte for oxidation in the production process, which has small environmental pollution, long service life of the electrolyte and low industrial cost.

[0048] (3) The present application uses pressure spraying to realize one-step rapid loading of titanium oxide and manganese oxide in the loading process, which has shorter time consumption, does not require step-by-step synthesis of the catalyst, has simple reaction conditions, low device requirements, can be mass-produced in industry, has a light and thin integrated structure, can be coupled to air purifier filter cartridges and other products, and has high firmness of the active component and the carrier, and is not easy to fall off.

[0049] (4) The present application uses only non-noble metal oxides as active components, which can achieve high catalytic activity of formaldehyde, reduce the amount of drugs, reduce costs and simplify the preparation process. The catalyst can also remove formaldehyde at room temperature. The modified catalyst can reduce the formaldehyde concentration from 0.9 ppm to 0.06 ppm in 25 minutes at room temperature, and can reduce the formaldehyde concentration from 0.9 ppm to 0.03 ppm in 60 minutes, which has excellent activity effect, is better than the best catalyst in patent CN114588892A, and has a formaldehyde residual concentration lower than the highest requirement (<0.07 mg / m 3 ) of the current national standard for indoor formaldehyde concentration limit, and has certain improvement in service life and moisture resistance. BRIEF DESCRIPTION OF DRAWINGS

[0050] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0051] Figure 1 A scanning electron microscope image of the gamma-Al2O3 / Al carrier prepared in Example 1;

[0052] Figure 2 A formaldehyde catalytic decomposition efficiency diagram of the MnO2 / K / TiO2 / gamma-Al2O3 / Al catalyst prepared in Example 1;

[0053] Figure 3 A formaldehyde catalytic decomposition efficiency diagram of the TiO2 / gamma-Al2O3 / Al catalyst prepared in Example 1;

[0054] Figure 4 Graph showing the catalytic decomposition efficiency of formaldehyde for the Mn02 / K / γ-A1203 / AI catalyst prepared in Example 2;

[0055] Figure 5 Graph showing the decomposition efficiency of formaldehyde for the manganese-based catalysts prepared in Example 1, Example 2, and Comparative Example 1;

[0056] Figure 6 Scanning electron microscope image of the Mn02 / K / Ti02 / γ-A1203 / AI catalyst prepared in Example 1;

[0057] Figure 7 Scanning electron microscope image of the Mn02 / K / γ-A1203 / AI catalyst prepared in Example 2;

[0058] Figure 8 Graph showing the catalytic decomposition efficiency of formaldehyde for the catalysts prepared in Examples 4-6 as a purification filter cartridge;

[0059] Figure 9 Graph showing the catalytic decomposition efficiency of formaldehyde for the catalysts prepared in Examples 3, 7-9 as a purification filter cartridge;

[0060] Figure 10 Graph showing the appearance of the supports selected for Examples 3-9, a-punched aluminum plate; b-honeycomb aluminum; c-spherical alumina; d-cylindrical activated carbon; e-carbon cloth; f-HEPA mesh;

[0061] Figure 11 Graph showing the comparison of the powdering of the manganese-based catalysts prepared in Example 1 (right side) and Comparative Example 1 (left side). DETAILED DESCRIPTION

[0062] A number of exemplary embodiments of the present application are now described in detail below. The following description of the exemplary embodiments is not intended to be a limitation on the scope of the present application, but rather merely an illustration.

[0063] 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 present application. Additionally, for the purposes of the present application, the term "about" means plus or minus 10% of the value being described, unless otherwise indicated. Furthermore, it is to be understood that the use of a singular term, such as, but not limited to, "a," "an," and "the" include the plural and vice versa unless the context clearly dictates otherwise. It is also to be understood that the term "or" as used herein encompasses both exclusive and inclusive meanings unless otherwise indicated. Additionally, it is to be understood that the use of "or" in the "and / or" context includes an exclusive "or" at least once true in the claim context.

[0064] Unless otherwise indicated, all technical and scientific terms have the same meaning as those one of ordinary skill in the art of the disclosure would understand. Although preferred methods and materials are described, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure. All documents mentioned herein are incorporated by reference to disclose and describe in further detail the methods and / or materials associated with the documents. In the case of conflict between the content of the specification and that of any document incorporated by reference, the content of the specification controls.

[0065] Many modifications and variations of the present disclosure described in the specification are possible without departing from the scope or spirit of the present disclosure. Other implementations of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the present disclosure. The specification and examples of the present disclosure are illustrative only.

[0066] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", and the like are open-ended terms that are intended to permit but not limit the inclusion of elements or the number of elements, as well as the possibility that one or more other elements can be added or otherwise included.

[0067] Normal temperature in the embodiments of the present disclosure refers to 25±2℃.

[0068] Example 1

[0069] After the aluminum mesh (Yejia Hardware and Building Materials Business Department of Qindong City, 1016 type aluminum material, mesh size 1*2mm) was pretreated with 10wt% NaOH solution and 10wt% HNO3 solution for 4min and 2min respectively, it was anodized in a sulfuric acid solution with a concentration of 4mol / L at 3℃ for 2.5h, and the oxidation tank voltage was set to 5-stage gradient: 18V, 20V, 22V, 24V, 26V, and the oxidation time of each stage was 15min, 25min, 35min, 45min, and 30min respectively. The voltage of each stage was kept constant during oxidation. After oxidation, the mesh was soaked in the sulfuric acid solution for 45min. After rinsing and drying, the mesh was calcined at 350℃ for 1h. Then the mesh was hydrated in deionized water at 80℃ for 1h and dried at room temperature. Finally, the mesh was calcined at 500℃ for 4h to obtain a γ-Al2O3 / Al carrier.

[0070] A neutral silica sol (30wt% SiO2, pH=7), deionized water, and titanium dioxide with a particle size of 100nm were weighed in a mass ratio of 5:2:2. Ammonium polyacrylate was added at a mass fraction of 1wt% of the titanium dioxide. After continuous stirring at 30℃ for 2h, 5wt% deionized water was added, and stirring was continued for 1h. After stirring was completed, the mixture was uniformly sprayed onto the surface of the γ-Al2O3 / Al carrier. The carrier surface was completely turned white, and the process was stopped. The mixture was dried at 160℃ for 1h. After drying, a titanium-based catalyst was prepared, which was denoted as TiO2 / γ-Al2O3 / Al.

[0071] The TiO2 / γ-Al2O3 / Al catalyst is immersed in 0.2 mol / L potassium permanganate solution, and is fully immersed for 30 min under stirring in a thermostatic water bath at 60°C. A mixed solution of 0.5 mol / L manganese sulfate and 0.05 mol / L potassium sulfate is prepared. After the carrier is fully immersed, the mixed solution of manganese sulfate and potassium sulfate is atomized into small droplets of 0.3-1 mm in size by using a pressure spray gun, and is uniformly sprayed onto the front and back surfaces of the carrier. The manganese dioxide with fine particle size and uniform dispersion is generated by the rapid reaction of the mixed solution with the potassium permanganate solution adsorbed on the surface of the carrier. The angle is kept as an acute angle during the spraying process, and the spraying pressure is 1.8 MPa. The spraying process is stopped when the purple-red color on the surface of the carrier is completely converted into brown-black. The manganese dioxide precipitate that is not firmly combined with the surface of the aluminum mesh is washed off, and the above steps are repeated for 12 rounds. After washing, the manganese titanium-based catalyst is naturally air-dried for 6 h, and is denoted as MnO2 / K / TiO2 / γ-Al2O3 / Al.

[0072] Figure 1 The scanning electron microscope image of the γ-Al2O3 / Al carrier prepared in Example 1 is shown in FIG. 1. Figure 1 As can be seen, the prepared γ-Al2O3 / Al carrier has a dense and ordered porous nanostructure, a large specific surface area, and thus good hydrophilicity and adsorption performance, and can be used for catalyst loading.

[0073] Example 2

[0074] The same as Example 1, except that the loading of titanium dioxide is cancelled, and the γ-Al2O3 / Al carrier is directly immersed in 0.2 mol / L potassium permanganate solution, taken out after full immersion, and then sprayed with a mixed solution of 0.5 mol / L manganese sulfate and 0.05 mol / L potassium sulfate for reaction. The above steps are repeated for 12 rounds, and the manganese-based catalyst is prepared by reaction, and is denoted as MnO2 / K / γ-Al2O3 / Al.

[0075] Example 3

[0076] The same as Example 2, except that the aluminum mesh used for anodic oxidation is replaced by a punched aluminum plate (purchased from Shenzhen Hongnian Metal Material Co., Ltd., with a hole diameter of 2 mm) as the carrier for anodic oxidation, and is denoted as MnO2 / K / punched aluminum plate.

[0077] Example 4

[0078] The same as Example 2, except that the γ-Al2O3 / Al obtained by anodic oxidation is not used as the carrier, and spherical aluminum oxide (purchased from Henan Dongshuo Environmental Protection Filter Material Co., Ltd., with a particle size of 3-5 mm and a specific surface area of about 300 m 2(g) As a carrier, after being hydrated in deionized water at 80°C for 1 h and dried in a vacuum drying oven at 80°C for 12 h, it was immersed in 0.2 mol / L potassium permanganate solution, sprayed with a mixed solution of 0.5 mol / L manganese sulfate and 0.05 mol / L potassium sulfate, and reacted. Repeat the above steps, spray 6 rounds, prepare a manganese-based catalyst, marked as MnO2 / K / spherical alumina.

[0079] Example 5

[0080] The same as Example 2, except that the γ-Al2O3 / Al obtained by anodic oxidation is not used as a carrier, and a honeycomb aluminum (purchased from Zhongshan Shangcheng Environmental Protection Technology Co., Ltd., pore size 2 mm, thickness 2 cm) is directly used as a carrier. The honeycomb aluminum is treated with 10wt% NaOH solution and 10wt% HNO3 solution for 4 min and 2 min respectively to make its surface rough. Then it is immersed in 0.2 mol / L potassium permanganate solution, sprayed with a mixed solution of 0.5 mol / L manganese sulfate and 0.05 mol / L potassium sulfate, and reacted. Repeat the above steps, spray 12 rounds, prepare a manganese-based catalyst, marked as MnO2 / K / honeycomb aluminum.

[0081] Example 6

[0082] The same as Example 2, except that the γ-Al2O3 / Al obtained by anodic oxidation is not used as a carrier, and a coal columnar activated carbon (purchased from Guangdong Wanghong Activated Carbon Co., Ltd., particle size 2-4 mm, specific surface area about 800 m 2 (g) As a carrier, after being hydrated in deionized water at 95°C for 2 h, pretreated to remove surface dust, dried in a vacuum drying oven at 80°C for 12 h, immersed in 0.2 mol / L potassium permanganate solution, sprayed with a mixed solution of 0.5 mol / L manganese sulfate and 0.05 mol / L potassium sulfate, and reacted. Repeat the above steps, spray 6 rounds, prepare a manganese-based catalyst, marked as MnO2 / K / columnar activated carbon.

[0083] Example 7

[0084] The same as Example 2, except that the γ-Al2O3 / Al obtained by anodic oxidation is not used as a carrier, and a carbon cloth (purchased from Jinan Weishirong Purification Material Co., Ltd., with activated carbon powder loaded on the fiber cloth) is directly used as a carrier. It is immersed in 0.2 mol / L potassium permanganate solution, sprayed with a mixed solution of 0.5 mol / L manganese sulfate and 0.05 mol / L potassium sulfate, and reacted. Repeat the above steps, spray 4 rounds, prepare a manganese-based catalyst, marked as MnO2 / K / carbon cloth.

[0085] Example 8

[0086] The same as example 7, except that activated carbon filter cotton (purchased from Suzhou Carbon Cyclone Activated Carbon Co., Ltd., activated carbon powder loaded on polyurethane foam) was used as the carrier to prepare a manganese-based catalyst, denoted as MnO2 / K / activated carbon filter cotton.

[0087] Example 9

[0088] The same as example 7, except that HEPA net (purchased from Juyou Environmental Protection Purification Co., Ltd., with certain hydrophilicity) was used as the carrier to prepare a manganese-based catalyst, denoted as MnO2 / K / HEPA.

[0089] Comparative example 1 (the best-performing catalyst in CN114588892A)

[0090] The aluminum net was pretreated with 10wt% NaOH solution for 4min and 10wt% HNO3 solution for 2min, respectively, and then placed in an anodizing tank to be anodized in an oxalic acid solution with a current density of 25A / m 2 2 and a concentration of 0.4mol / L at 20℃ for 10h, air-dried, and then calcined at 350℃ for 1h; then hydrated in deionized water at 80℃ for 1h, dried at room temperature; and then calcined at 500℃ for 4h to obtain a γ-Al2O3 / Al carrier.

[0091] The above γ-Al2O3 / Al carrier was immersed in a potassium titanium oxalate solution with a concentration of 0.23mol / L at 85℃ for 4h, air-dried, and then calcined at 500℃ for 4h. Then the γ-Al2O3 / Al carrier loaded with titanium was immersed in a potassium permanganate solution with a concentration of 0.4mol / L at 50℃ for 40min. Then vacuum dried at 50℃ for 2h to prepare a flexible purification filter element, denoted as Mn / Ti / γ-Al2O3 / Al-original patent.

[0092] Test example 1

[0093] The catalyst obtained in the examples of the present application was evaluated for application, and the application evaluation conditions were as follows: according to national standard GB-18204.2-2014, 1 piece of 28*38cm catalyst or 300g of granular catalyst was placed in an air purifier (air volume: 250-300m 3 / h), a certain volume of formaldehyde solution was injected into a 3m 3 cabin, and after volatilization and uniform mixing, the formaldehyde concentration was 1mg / m 3 , the formaldehyde removal rate test was carried out under the conditions of normal pressure, reaction temperature of 25℃, relative humidity of 40-60%, and cross-sectional flow rate of 2.5m / s.

[0094] Test example 2

[0095] The same as test example 1, the air purifier is replaced by a desktop purifier (air volume: 30-80 m 3 / h) for testing, and 1 piece of 10*10 cm or 30 g of catalyst is put in.

[0096] Test example 3

[0097] The catalysts obtained from example 1 and comparative example 1 of the present application are subjected to falling experiment evaluation, and the evaluation conditions are: 1 piece of 10*10 cm catalyst is cut, weighed and recorded, and then placed at a height of 30 cm to fall naturally, and the catalyst mass after the first, fifth, tenth and thirtieth times is recorded, the mass loss rate (calculated from the carrier loading) is calculated, and the catalyst powder loss rate test is performed.

[0098] Figure 2 The MnO2 / K / TiO2 / γ-Al2O3 / Al catalyst prepared in example 1 is used as a formaldehyde degradation efficiency schematic diagram of a purification filter core. From Figure 2 It can be seen that the MnO2 / K / TiO2 / γ-Al2O3 / Al can reduce the formaldehyde in the cabin to below the national standard value within 25 min, the formaldehyde removal efficiency within 30 min is 95.0%, and the formaldehyde removal efficiency within 60 min is 98.1%, which shows that the purification filter core has good formaldehyde removal effect.

[0099] Figure 4 The MnO2 / K / γ-Al2O3 / Al catalyst prepared in example 2 is used as a formaldehyde degradation efficiency schematic diagram of a purification filter core. From Figure 4 It can be seen that the MnO2 / K / γ-Al2O3 / Al has a formaldehyde removal efficiency of 86.0% within 30 min, which is 9.0% lower than that of MnO2 / K / TiO2 / γ-Al2O3 / Al, and the formaldehyde removal rate within 60 min is 96.3%. This shows that titanium dioxide doping can effectively improve the formaldehyde degradation rate of the filter core.

[0100] Figure 5 The manganese-based catalysts prepared in example 1, example 2 and comparative example 1 are used as a comparison diagram of formaldehyde degradation efficiency of a purification filter core, from Figure 5 It can be seen from the comparison diagram that the MnO2 / K / TiO2 / γ-Al2O3 / Al has a faster formaldehyde degradation rate than the catalyst of comparative example 1, can reach below the national standard value faster, and has better catalytic activity.

[0101] Figure 6 The MnO2 / K / TiO2 / γ-Al2O3 / Al catalyst prepared in example 1 is used as a scanning electron microscope diagram of a purification filter core, from Figure 6It can be seen that the catalyst surface is successfully loaded with a layer of nanoflower spherical manganese dioxide (delta crystal form) with a particle size of about 250-300 nm, which plays an effective role in catalytic decomposition of formaldehyde.

[0102] Figure 7 The scanning electron microscope image of the MnO2 / K / γ-Al2O3 / Al catalyst prepared in Example 2 as a purification filter core is shown in Fig. 2. Figure 7 It can be seen that the catalyst surface is also successfully loaded with a layer of nanoflower spherical manganese dioxide (delta crystal form), which plays an effective role in catalytic decomposition of formaldehyde, and the particle size of the manganese dioxide on the surface of the MnO2 / K / γ-Al2O3 / Al catalyst is about 150-200 nm, which is relatively small, so the catalytic activity is weaker than that of the MnO2 / K / TiO2 / γ-Al2O3 / Al catalyst prepared in Example 1.

[0103] Figure 8 The formaldehyde degradation efficiency diagram of the catalyst prepared in Examples 4-6 as a purification filter core is shown in Fig. 4, which is tested according to the test conditions of Test Example 2.

[0104] Figure 9 The formaldehyde degradation efficiency diagram of the catalyst prepared in Examples 3, 7-9 as a purification filter core is shown in Fig. 3, which is tested according to the test conditions of Test Example 1.

[0105] Figure 10 The appearance diagram of the carriers selected in Examples 3-9 is shown in Fig. 5, a-punched aluminum plate; b-honeycomb aluminum; c-spherical alumina; d-columnar activated carbon; e-carbon cloth; f-HEPA net, the carriers all have a certain hydrophilicity.

[0106] Figure 11 The catalyst prepared in Example 1 (right side) and Comparative Example 1 (left side) is compared in terms of powder falling, which is tested according to the test conditions of Test Example 3. It can be seen from Fig. 6 that Example 1 has no component falling off, while Comparative Example 1 has obvious powder falling, and there are more manganese dioxide powders on the white paper at the bottom. Figure 10 It can be seen from Fig. 6 that Example 1 has no component falling off, while Comparative Example 1 has obvious powder falling, and there are more manganese dioxide powders on the white paper at the bottom.

[0107] Table 1 is a summary of the formaldehyde degradation removal rate data of Examples 1-9, and it can be seen that the manganese and / or titanium loaded on various carriers by the method of the present application all have good catalytic activity. Under a wind volume of 250 m 3 / h, the formaldehyde degradation rate in 1 h can reach more than 90%, and under a wind volume of 80 m 3 / h, the formaldehyde degradation rate in 1 h can reach more than 60%, which shows that the loading method has wide applicability and can have good formaldehyde catalytic activity on different carriers.

[0108] Table 1

[0109]

[0110]

[0111] The comparison of part of the properties of the modified catalyst Mn / Ti / γ-Al2O3 / Al prepared in the patent CN 114588892 A and the MnO2 / K / TiO2 / γ-Al2O3 / Al prepared in the present application (the same test standards) is shown in Table 2. As shown in Table 2, the activity of the catalyst can be greatly improved by the present application.

[0112] Table 2

[0113]

[0114] Table 3 is a summary of the related falling experiment data of the manganese-based catalyst prepared in Example 1. It can be seen that the manganese and / or titanium catalyst prepared by the method of the present application has a firm combination of the loaded components. After 30 consecutive falls, the mass loss rate still remains 0%, which shows that the method has good process advantages, does not fall off, and is suitable for the preparation of catalysts.

[0115] Table 3

[0116]

[0117]

[0118] Note: Mass loss rate (%) = {total mass of catalyst before test (g) - total mass of catalyst after test (g)} / {total mass of catalyst before test (g) * manganese loading of manganese dioxide (wt %)}.

[0119] Table 4 is a summary comparison of the preparation time of the catalyst prepared in the present application and the catalyst prepared in the patent CN 114588892 A. As shown in Table 4, the total preparation time of the present application is 8-29 h, while the total preparation time of the patent CN 114588892 A is 46-108 h, which is greatly shortened.

[0120] Among them, the MnO2 / K / TiO2 / γ-Al2O3 / Al catalyst prepared in Example 1 of the present application (≈25 min to reach the national standard for the degradation of formaldehyde) has a production efficiency improved by 282.3% compared with the Mn / Ti / γ-Al2O3 / Al catalyst prepared in Example 6 of the patent CN 114588892 A (the best effect: ≈40 min to reach the national standard for the degradation of formaldehyde), and has better catalytic activity;

[0121] Further, the MnO2 / K / γ-Al2O3 / Al catalyst prepared in Embodiment 2 of the present application (≈45 min to reach the national standard for degradation of formaldehyde) still has a production efficiency increased by 106.7% and better catalytic activity compared with the Mn / γ-Al2O3 / Al catalyst prepared in Embodiment 1 of CN 114588892 A (shortest preparation time; >100 min to reach the national standard for degradation of formaldehyde);

[0122] The catalyst synthesized by the preparation method in the present application has better catalytic activity and higher production efficiency, has industrial practical value, and has a simple loading method, wide application range, and can be produced in batches, and is widely used in the field of air purification.

[0123] Table 4

[0124]

[0125] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for loading manganese onto a hydrophilic carrier material, characterized in that, Includes the following steps: Ammonium polyacrylate is added to a mixed solution of neutral silica sol, water and titanium dioxide, and stirred until homogeneous. Then water is added and stirred until homogeneous again. The solution is then sprayed onto the surface of a hydrophilic carrier material. After the surface of the hydrophilic carrier material turns completely white, it is dried to obtain a titanium-loaded hydrophilic carrier material. The titanium-loaded hydrophilic carrier material is placed in a potassium permanganate solution and fully immersed; it is then removed and a mixed solution of manganese salt and potassium salt, or manganese salt and sodium salt, is sprayed onto the surface of the immersed titanium-loaded hydrophilic carrier material. The spraying angle is kept acute. After the purplish-red surface of the titanium-loaded hydrophilic carrier material completely turns brownish-black, it is rinsed, sprayed repeatedly, rinsed and dried. The hydrophilic carrier material is γ-Al2O3 / Al carrier, perforated aluminum plate, carbon cloth, HEPA mesh or activated carbon filter cotton. The preparation method of the γ-Al2O3 / Al support is as follows: the aluminum substrate obtained by anodizing is calcined to obtain porous anodic aluminum oxide; a hydroxyl-rich boehmite is obtained through a hot water synthesis reaction; and the γ-Al2O3 / Al support is obtained through a second calcination. The manganese salt is manganese sulfate, manganese chloride, or manganese nitrate; the potassium salt is potassium sulfate or potassium chloride; the sodium salt is sodium sulfate or sodium chloride. The immersion temperature is 20-100℃, and the time is 10-60 minutes; The spraying pressure is 1-2.5 MPa.

2. The method for loading manganese onto a hydrophilic carrier material according to claim 1, characterized in that, The mass ratio of neutral silica sol, water, and titanium dioxide in the mixed solution is 5:2:2; Ammonium polyacrylate accounts for 1 wt% of the mass of titanium dioxide.

3. The method for loading manganese onto a hydrophilic carrier material according to claim 1, characterized in that, After adding ammonium polyacrylate, the stirring temperature is 25-40℃ and the stirring time is 1-3 hours; Continue stirring for 1-3 hours after adding water.

4. A modified catalyst, characterized in that, Obtained by the method according to any one of claims 1-3.

5. The application of the modified catalyst according to claim 4 in formaldehyde removal.

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