Photocatalyst spray and method for preparing the same

Abstract

The application discloses a photocatalyst spray and a preparation method thereof, and belongs to the field of photocatalysis. The photocatalyst spray comprises photocatalyst powder and water; the solid content of the photocatalyst powder in the photocatalyst spray is 0.0001-10.00 wt%; the photocatalyst powder comprises a silicon dioxide in-situ core and titanium dioxide attached to the silicon dioxide in-situ core, wherein the titanium dioxide is in an anatase type; the apparent particle is spherical, and the particle size is less than 100 nm; the BET specific surface area is greater than or equal to 100 m 2 / g, and the problems of strong dependence on light conditions and large pollution of the existing photocatalyst catalyst are solved.

Description

Technical Field

[0001] This invention relates to the field of photocatalysis, specifically to a photocatalytic spray and its preparation method. Background Technology

[0002] Photocatalytic sprays are widely used for removing organic matter indoors and in vehicles. The main drawbacks of existing photocatalytic sprays are their dependence on specific light conditions, significantly reduced effectiveness, and potential secondary pollution and health risks.

[0003] Specifically, there are the following main points: (1) Core weakness: It is extremely dependent on light conditions; this is the most fundamental limitation of photocatalytic spray. Its core components (such as nano titanium dioxide) need to absorb ultraviolet light to work effectively. Indoor ultraviolet light is severely insufficient: In the rooms where we live, the window glass blocks most of the ultraviolet light in the sunlight, and the intensity of ultraviolet light from ordinary lamps is negligible. Calculations show that when the distance from the light source is 2.5 meters, the intensity of light radiation will be lost by more than 2,500 times, and the catalytic efficiency is extremely low. In places where formaldehyde is most likely to accumulate, such as drawers, the back of cabinets, and under the bed, where light cannot reach, the spray basically has no effect. Although there are "visible light response" or even "no light" technology products on the market, they are either limited in effect (blue light absorption rate of less than 5%) or expensive and rare in the market; (2) by adding precious metal / manganese-based catalyst modification technology, but heavy metals are not friendly to human health during use and heavy metal poisoning is very easy to occur; or strong oxidants such as chlorine dioxide are used directly, which, while eliminating formaldehyde, also generate new chlorine pollution, accelerates the aging of furniture, home appliances and leather products, and causes metal parts to rust; the preparation process of using alcohol to dissolve titanium source will also cause environmental pollution; (3) Real dilemma: the actual effect is far from the publicity and is ineffective against high concentration pollution sources: facing artificial board furniture that continuously releases formaldehyde (the release cycle can reach 3-15 years), the existing photocatalyst sprays on the market seem powerless. In a high concentration of formaldehyde environment, the reaction products may also cover the coating surface, leading to "poisoning" failure. Summary of the Invention

[0004] To alleviate or partially alleviate the above-mentioned technical problems, the solution of the present invention is as follows:

[0005] A photocatalyst spray comprises photocatalyst powder and water; the solid content of the photocatalyst powder in the photocatalyst spray is 0.0001-10.00 wt%.

[0006] The photocatalyst powder comprises an in-situ silica core and titanium dioxide attached to the silica core, wherein the titanium dioxide is anatase type; the apparent particles are spherical with a particle size of less than 100 nm; and the BET specific surface area is ≥100 m². 2 / g.

[0007] This solution also provides a method for preparing the aforementioned photocatalytic spray, including:

[0008] Step S1: Mix titanate, nano-silica and ammonium-rich solution to carry out the reaction;

[0009] Step S2: After the reaction is complete, the product is separated and washed with anhydrous ethanol.

[0010] Step S3: The washed product is subjected to a first-stage calcination and a second-stage calcination. The calcined product is then ground to obtain photocatalyst powder.

[0011] Step S4: Disperse the photocatalyst powder and dispersant in water to obtain a photocatalyst spray.

[0012] Preferably, in step S1, the titanate is selected from tetrabutyl titanate or tetraisobutyl titanate;

[0013] Preferably, the ammonium-rich solution is selected from any one or more combinations of aqueous solutions of ammonium salts, ammonia water, liquid ammonia, or organic amine salts;

[0014] The ammonium salt is selected from one of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate, ammonium bicarbonate, or ammonium sulfide;

[0015] The organic amine salt is selected from methylamine or ethylamine.

[0016] Preferably, step S1 includes:

[0017] First, nano-silica is added to an ammonium-rich solution to obtain a silica dispersion;

[0018] Titanate ester is then added dropwise to the silica dispersion. After the addition is complete, the reaction is carried out at a constant temperature.

[0019] Preferably, the mass-to-volume ratio of nano-silica to ammonium-rich solution in step S1 is 1-200 g / L;

[0020] Preferably, the molar concentration of the ammonium-rich solution is 0.01-2.5 mol / L.

[0021] Preferably, the ratio of nano-silica to titanate in step S1 is 1: (1-1000) g / mL.

[0022] Preferably, the first roasting in step S3 includes: first increasing the temperature from room temperature to 450°C at a rate of 2°C / min;

[0023] The second roasting process involves increasing the temperature from 450°C to 600°C at a rate of 1°C / min and holding the temperature for 2–3 hours.

[0024] During the roasting process, amorphous TiO2 is transformed into pure anatase, suppressing the rutile impurity phase; SiO2 remains amorphous.

[0025] Preferably, the grinding in step S3 is performed by air jet milling, planetary ball milling, or agate grinding through a 400–1000 mesh sieve.

[0026] Preferably, the content of the dispersant in step S4 is 0.01wt%-0.05wt%; the dispersant is selected from metal phosphates or organic dispersants, the metal phosphates are selected from sodium tripolyphosphate, sodium hexametaphosphate or sodium pyrophosphate; the organic dispersants are selected from at least one of triethylhexyl phosphate, sodium dodecyl sulfate, methyl pentanol, cellulose derivatives, polyacrylamide, glucon or fatty acid polyethylene glycol esters.

[0027] An amphiphilic reagent is added as a dispersant to form a stable suspension in order to prevent particle sedimentation and aggregation.

[0028] The technical solution of this invention has the following beneficial technical effects:

[0029] It can continuously and rapidly produce modified nano-SiO2-TiO2 photocatalyst powder. SiO2 is coated in anatase TiO2 in an amorphous form, which has high production efficiency, good catalytic activity, good transparency, and excellent safety and environmental friendliness.

[0030] The production process of this solution does not require the use of alcohol solutions to dissolve titanate and nano-silica, making the preparation process green and environmentally friendly. Attached Figure Description

[0031] Figure 1 These are the XRD and SEM images of the photocatalyst powder prepared in Example 1;

[0032] Figure 2 This is a BET specific surface area test diagram of the photocatalyst powder prepared in Example 1;

[0033] Figure 3 This is a picture of the photocatalyst spray from this solution;

[0034] Figure 4 This is the test report on the formaldehyde removal rate of the photocatalyst in this solution;

[0035] Figure 5 The results show the photocatalytic removal of Rhodamine B by the blank sample, the photocatalyst of this scheme, and commercially available TiO2 for 2 hours under sunlight. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] Example 1

[0038] First, 50g of nano-silica was added to 1L of ammonium chloride solution with a molar concentration of 0.1mol / L to obtain a silica dispersion.

[0039] Then add 100 mL of tetrabutyl titanate to the silica dispersion, and after the addition is complete, maintain the reaction temperature.

[0040] After the reaction is complete, the product is separated and washed with anhydrous ethanol;

[0041] The washed product was first heated from room temperature to 450°C at 2°C / min; then heated from 450°C to 600°C at 1°C / min and held for 2 hours. The calcined product was then ball-milled through a 500-mesh sieve to obtain photocatalyst powder.

[0042] A photocatalyst spray is obtained by dispersing photocatalyst powder and sodium tripolyphosphate with a solid content of 3 wt% in deionized water.

[0043] Example 2

[0044] First, 200g of nano-silica was added to 1L of ammonium sulfide solution with a molar concentration of 2.5mol / L to obtain a silica dispersion.

[0045] Then, 200 mL of tetraisobutyl titanate was added dropwise to the silica dispersion. After the addition was complete, the reaction was carried out at a constant temperature. After the reaction was complete, the product was separated and washed with anhydrous ethanol.

[0046] The washed product was first heated from room temperature to 450°C at 2°C / min; then heated from 450°C to 600°C at 1°C / min and held for 3 hours. The calcined product, agate, was ground and passed through a 400-mesh sieve to obtain photocatalyst powder.

[0047] A photocatalyst spray is obtained by dispersing photocatalyst powder and triethylhexylphosphoric acid with a solid content of 10 wt% in deionized water.

[0048] Example 3

[0049] First, 1g of nano-silica was added to 1L of ammonia solution with a molar concentration of 0.01mol / L to obtain a silica dispersion.

[0050] Then, 1000 mL of tetrabutyl titanate was added dropwise to the silica dispersion. After the addition was complete, the reaction was carried out at a constant temperature. After the reaction was completed, the product was separated and washed with anhydrous ethanol.

[0051] The washed product was first heated from room temperature to 450°C at 2°C / min; then heated from 450°C to 600°C at 1°C / min and held for 3 hours. The calcined product was then pulverized by air jet and passed through a 1000-mesh sieve to obtain photocatalyst powder.

[0052] A photocatalyst spray is obtained by dispersing photocatalyst powder and sodium dodecyl sulfate at a solid content of 0.0001 wt% in deionized water.

[0053] Example 4

[0054] First, 20g of nano-silica was added to 1L of ammonium chloride solution with a molar concentration of 0.2mol / L to obtain a silica dispersion.

[0055] Then, add 40 mL of tetrabutyl titanate to the silica dispersion. After the addition is complete, maintain the reaction temperature.

[0056] After the reaction is complete, the product is separated and washed with anhydrous ethanol;

[0057] The washed product was subjected to a first-stage calcination and a second-stage calcination. The calcined product was then ball-milled and passed through a 400-mesh sieve to obtain photocatalyst powder. The first calcination included: heating from room temperature to 450°C at a rate of 2°C / min; the second calcination included: heating from 450°C to 600°C at a rate of 1°C / min and holding at that temperature for 2.5 h.

[0058] A photocatalyst spray is obtained by dispersing photocatalyst powder and sodium dodecyl sulfate (0.05 wt%) in deionized water with a solid content of 2 wt%.

[0059] Example 1: Ammonia-modified nano-SiO2-TiO2 powder was prepared by polymerization-hydrolysis. After high-temperature calcination and grinding, the photocatalytic powder mainly exhibited anatase TiO2 crystal structure. Figure 1 As shown in Figure a, the strongest peak in the spectrum is located at 2θ≈25.3°, corresponding to the characteristic crystal plane of anatase (101); subsequently, ~37.8°: (004) crystal plane, ~48.1°: (200) crystal plane, ~54°~55°: (105) / (211) crystal plane, ~62.7°: (204) crystal plane appear in sequence, proving that amorphous TiO2 is transformed into pure anatase after two-stage high-temperature calcination; the strongest characteristic peak of rutile at 27.4° does not appear, indicating that there is no rutile impurity phase and the crystal purity is high.

[0060] In the 2θ≈20–25° range, baseline elevation and diffuse broad bulges are visible, typical scattering characteristics of amorphous silica. The absence of sharp diffraction peaks for crystalline SiO2 throughout the spectrum indicates that SiO2 maintained its amorphous structure throughout the polymerization-hydrolysis preparation and subsequent calcination processes, being amorphously coated and doped within anatase TiO2 without the formation of titanium silicate or crystalline silicon oxide impurities. Furthermore, the absence of diffraction peaks for amino-related crystalline byproducts, titanium nitride, and other impurities suggests that the amino modification was a surface functional group modification, without the formation of crystalline nitrogen-containing phases. The modification occurred only on the powder surface and did not alter the main crystal structure.

[0061] Figure 1 The SEM image of b shows that the apparent particles are spherical and the particle size is less than 100 nm.

[0062] Figure 2 The prepared photocatalytic powder exhibits an extremely high BET specific surface area, reaching 100 m². 2 / g or more, far superior to commercially available nano-titanium dioxide (e.g., Evonik's nano-titanium dioxide has a specific surface area of ​​approximately 30~60m²). 2 / g).

[0063] Photocatalyst powder with a solid content of 5 wt% was dispersed in deionized water to obtain a photocatalyst spray, such as... Figure 3 As shown, the prepared photocatalyst spray is a blue transparent solution, which we call "Tech Blue." The blue color is more noticeable against a dark background, while it appears colorless against a white background, giving it a strong technological feel. Figure 4 The test report showed that, under 30W fluorescent light irradiation for 24 hours, it could reduce the concentration of 2.4 mg / m³. 3 The formaldehyde level dropped to 0.069 mg / m³. 3 This means that the formaldehyde removal rate under fluorescent light for 24 hours exceeds 97%.

[0064] Using commercially available photocatalysts and the high specific surface area modified nano-titanium dioxide photocatalyst of this solution, a 50 mg / L Rhodamine B aqueous solution was exposed to direct sunlight for 2 hours. The fading of Rhodamine B was as follows: Figure 5 As shown, the blank sample without photocatalyst remained a bright red, the sample with commercially available Evonik-TiO2 photocatalyst still showed a noticeable light red hue, while the sample with the photocatalyst from this solution completely lost its color, becoming a colorless and transparent liquid. This demonstrates that the photocatalyst from this solution exhibits significantly stronger photocatalytic degradation performance for dyes than the commercially available Evonik-TiO2 photocatalyst.

[0065] To better illustrate the present invention, numerous specific details have been provided in the detailed embodiments described above. Those skilled in the art should understand that the present invention can be practiced even without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of the present invention.

[0066] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A photocatalytic spray, characterized in that, It includes photocatalyst powder and water; the solid content of the photocatalyst powder in the photocatalyst spray is 0.0001-10.00 wt%; The photocatalyst powder comprises an in-situ silica core and titanium dioxide attached to the silica core, wherein the titanium dioxide is anatase type; the apparent particles are spherical with a particle size of less than 100 nm; and the BET specific surface area is ≥100 m². 2 / g.

2. The method for preparing a photocatalytic spray according to claim 1, characterized in that, include: Step S1: Mix titanate, nano-silica and ammonium-rich solution to carry out the reaction; Step S2: After the reaction is complete, the product is separated and washed with anhydrous ethanol. Step S3: The washed product is subjected to a first-stage calcination and a second-stage calcination. The calcined product is then ground to obtain photocatalyst powder. Step S4: Disperse the photocatalyst powder and dispersant in water to obtain a photocatalyst spray.

3. The method for preparing a photocatalytic spray according to claim 2, characterized in that, In step S1, the titanate is selected from tetrabutyl titanate or tetraisobutyl titanate.

4. The method for preparing a photocatalytic spray according to claim 2, characterized in that, The ammonium-rich solution is selected from any one or more combinations of aqueous solutions of ammonium salts, ammonia water, liquid ammonia, or organic amine salts; The ammonium salt is selected from one of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate, ammonium bicarbonate, or ammonium sulfide; The organic amine salt is selected from methylamine or ethylamine.

5. The method for preparing a photocatalytic spray according to claim 2, characterized in that, Its features are, Step S1 includes: First, nano-silica is added to an ammonium-rich solution to obtain a silica dispersion; Titanate ester is then added dropwise to the silica dispersion. After the addition is complete, the reaction is carried out at a constant temperature.

6. The method for preparing a photocatalytic spray according to claim 5, characterized in that, In step S1, the mass-to-volume ratio of nano-silica to ammonium-rich solution is 1-200 g / L; The molar concentration of the ammonium-rich solution is 0.01-2.5 mol / L.

7. The method for preparing a photocatalytic spray according to claim 5, characterized in that, In step S1, the ratio of nano-silica to titanate is 1:(1-1000) g / mL.

8. The method for preparing a photocatalytic spray according to claim 2, characterized in that, The first roasting in step S3 includes: first raising the temperature from room temperature to 450°C at a rate of 2°C / min; The second roasting process involves increasing the temperature from 450°C to 600°C at a rate of 1°C / min and holding the temperature for 2–3 hours.

9. The method for preparing a photocatalytic spray according to claim 2, characterized in that, The grinding described in step S3 is air jet milling, planetary ball milling, or agate grinding through a 400–1000 mesh sieve.

10. The method for preparing a photocatalytic spray according to claim 2, characterized in that, In step S4, the content of the dispersant is 0.01wt%-0.05wt%; the dispersant is selected from metal phosphates or organic dispersants, the metal phosphates are selected from sodium tripolyphosphate, sodium hexametaphosphate or sodium pyrophosphate; the organic dispersants are selected from at least one of triethylhexyl phosphate, sodium dodecyl sulfate, methyl pentanol, cellulose derivatives, polyacrylamide, glucon or fatty acid polyethylene glycol esters.

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