Titanium-based modified honeycomb activated carbon composite material, preparation method and application thereof

Abstract

The application belongs to the technical field of honeycomb active carbon production, and particularly relates to a titanium modified honeycomb active carbon composite material, a preparation method and application thereof. The titanium modified honeycomb active carbon composite material is prepared by the following steps: mixing tetrabutyl titanate, acetylacetone and anhydrous ethanol, adding a dispersing agent and stirring to obtain a titanium dioxide sol; dipping the honeycomb active carbon in an alkali solution, washing, drying to obtain a substrate; vacuum negative pressure dipping the substrate in the sol; introducing inert gas to calcine the substrate to form an amorphous TiO2 layer; introducing ammonia gas to calcine to form nitrogen-doped TiO2; dipping the calcined substrate in F127 n-propanol solution, spraying an ethanol suspension containing polystyrene microspheres after the F127 n-propanol solution volatilizes, and calcining in inert gas to form through pores. The composite material provided by the application has excellent adsorption performance and high specific surface area, and can be used in the fields of air purification, industrial waste gas treatment, water body remediation and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of honeycomb activated carbon production, and particularly relates to a titanium modified honeycomb activated carbon composite material and a preparation method and application thereof. BACKGROUND

[0002] As a kind of porous adsorption material, activated carbon has been widely used in water treatment (such as removal of organic pollutants and heavy metal ions), air purification, industrial waste gas treatment (benzene series and hydrogen sulfide capture), medical protection (mask filter core) and electrochemical energy storage due to its high specific surface area, rich surface functional groups and controllable pore structure.

[0003] In recent years, in order to improve the functionality of activated carbon, many researchers have tried to give it catalytic and magnetic response properties by metal / metal oxide modification to form a dual functional composite material. However, although the existing commercial honeycomb activated carbon has the advantage of forming, it still has problems such as low adsorption capacity, single function and poor moisture resistance. The traditional modification technology (such as TiO2 loading) easily blocks the original pore, resulting in a decrease in specific surface area, and the mechanical strength is insufficient, which is difficult to meet the demand of complex working conditions, and it is difficult to balance the adsorption capacity, high catalytic activity and engineering applicability. SUMMARY

[0004] In view of the deficiencies of the prior art, the application provides a titanium modified honeycomb activated carbon composite material and a preparation method and application thereof.

[0005] The first aspect of the application is to provide a preparation method of a titanium modified honeycomb activated carbon composite material, comprising the following steps:

[0006] S1: titanium tetrabutoxide, acetylacetone and anhydrous ethanol are mixed in a molar ratio of 1-1.5:0.2-0.5:5, a dispersing agent is added and stirred to obtain a titanium dioxide sol;

[0007] S2: the honeycomb activated carbon is immersed in an alkali solution, washed and dried to obtain a substrate;

[0008] S3: the substrate is immersed in the titanium dioxide sol and vacuum negative pressure immersed;

[0009] S4: the substrate immersed in S3 is calcined under the condition of introducing inert gas to form an amorphous TiO2 layer, and then calcined under the condition of introducing ammonia to generate nitrogen-doped TiO2:

[0010] S5: the substrate obtained after calcination in S4 is immersed with F127 n-propanol solution, and after volatilization of the F127 n-propanol solution, an ethanol suspension containing polystyrene microspheres is sprayed, and the substrate is calcined in inert gas to form through pores, thereby obtaining the titanium modified honeycomb activated carbon composite material.

[0011] It should be noted that acetylacetone as a chelating agent can form a stable complex with Ti 4+ , inhibit the rapid hydrolysis of titanate, prevent the sol from condensation, and thus ensure the sol homogeneity, the complex decomposes to generate an amorphous TiO2 layer, the ultra-thin amorphous TiO2 layer can be loaded on the surface of the honeycomb activated carbon, avoid the blockage of the honeycomb activated carbon micropore, so that the honeycomb activated carbon always maintains a high specific surface area, and the adsorption capacity and adsorption ability are improved.

[0012] In some embodiments, the dispersion agent is carbon nanotube with a concentration of 0.8-1wt%, and the stirring and ultrasonic treatment is performed at 40-50℃ for 30-35min.

[0013] It should be noted that the carbon nanotube dispersion agent has abundant functional groups on the surface, which can prevent the aggregation of nano-TiO2 particles through electrostatic repulsion and steric hindrance effect, control the nano-TiO2 particle size in a suitable range, and improve the electrical conductivity of the material.

[0014] In some embodiments, the immersion time in S2 is 1-1.5h, the immersion temperature is 60-70℃, the washing step is washing with deionized water until neutral, and the drying temperature is 60-65℃.

[0015] In some embodiments, the alkali solution is sodium hydroxide solution or potassium hydroxide solution.

[0016] In the application, the honeycomb activated carbon is immersed in an alkali solution, the wall pores are corroded by the alkali solution, the micropores are expanded to mesopores, the diffusion resistance of micropore molecules is large, and the micropores are easily blocked by macromolecules or high-flow-rate gas, the presence of mesopores can reduce the diffusion resistance, accelerate the material transmission speed, reduce the pore blockage caused by pollutant retention, and improve the overall treatment efficiency.

[0017] In some embodiments, the vacuum degree in S3 is 0.02-0.04MPa, and the immersion time is 2-3h.

[0018] In some embodiments, in S4, the inert gas is introduced and calcined at 250-300℃ for 2-3h, and the ammonia gas is introduced and calcined at 500-600℃ for 1-1.5h.

[0019] In the application, the vacuum negative pressure immersion increases the penetration depth of the sol and improves the internal titanium loading uniformity; the segmented calcination method is used to calcine with inert gas, so as to avoid the reaction of activated carbon with oxygen at high temperature, form an amorphous TiO2 layer, prevent the collapse of the matrix and the loss of specific surface area, and retain a high active surface; then the ammonia gas is introduced for calcination, the NH3 molecules are preferentially adsorbed on the oxygen vacancies on the surface of TiO2, and at high temperature, the NH3 adsorbed on the surface is dissociated to generate NH2 - and H + , NH2 -The nitrogen atom in the F127 n-propanol solution replaces part of the oxygen atom in the TiO2 to form a N-TiO2 structure, reduces the band gap of the N-doped TiO2, and expands the light absorption range from only ultraviolet light to the visible light region, which can greatly improve the degradation rate of pollutants (such as toluene, formaldehyde, tetracycline, etc.) by the honeycomb activated carbon, and at the same time, it can reduce the dependence on ultraviolet lamps and reduce the risk of pump pollution.

[0020] In some embodiments, the concentration of the F127 n-propanol solution in S5 is 3-5wt%, the impregnation time is 30-40min, the volatilization temperature is 60-80℃, and the calcination temperature is 450-500℃, and the calcination time is 2-3h.

[0021] In some embodiments, the polystyrene microspheres have a particle size of 200-500nm, and the mass percentage of the polystyrene microspheres in the ethanol suspension is 20-25%.

[0022] It should be noted that the F127 n-propanol solution (i.e., a solution formed by dissolving Pluronic F127 in n-propanol) is used to impregnate the substrate, F127 (Pluronic F127) is a polyoxyethylene-polyoxypropylene block copolymer that can self-assemble into micelles in solution to guide the formation of mesopores; n-propanol is used to dissolve F127, and the micelles are fixed on the inner wall of the pore to form a pore structure at 60-80℃. The F127 at a concentration of 3-5wt% reaches the critical concentration for micelle formation in n-propanol, and the micelle spacing is moderate at this concentration, forming a through mesoporous network, loading nano-TiO2 particles in the mesopores, which can provide catalytic reaction space and optimize the mass transfer path.

[0023] In addition, the ethanol suspension containing polystyrene microspheres is sprayed, and the polystyrene microspheres are decomposed to generate gas products when calcined at high temperature, forming pores in the honeycomb activated carbon and leaving cavities to form macropores, thereby constructing a through macroporous structure in the material, which can improve the flow and diffusion of fluids. At the same time, inert gas is introduced when the polystyrene microspheres are calcined at high temperature, which is to prevent the polystyrene microspheres from burning violently, and to isolate oxygen to make the polystyrene microspheres pyrolyze at high temperature instead of burning. In the presence of oxygen, the local temperature will rise sharply due to the violent heat release, which will damage the pore structure of the activated carbon, and even cause the collapse of the carbon skeleton of the material.

[0024] The second aspect of the present application provides a titanium-based modified honeycomb activated carbon composite material.

[0025] The third aspect of the present application provides a titanium-based modified honeycomb activated carbon composite material for use in the field of adsorbent materials.

[0026] The titanium-based modified honeycomb activated carbon composite material provided by the present application can be applied to the fields of air purification, industrial waste gas treatment, water remediation, etc.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] 1、The present application loads an ultrathin amorphous TiO2 layer on the surface of honeycomb activated carbon through vacuum impregnation and staged calcination, covers the pore surface but does not block the pores, retains a high specific surface area, provides high catalytic active sites, improves mass transfer efficiency, forms an N-TiO2 structure through ammonia calcination, and expands the light absorption range. The titanium-based modified honeycomb activated carbon composite provided by the technical scheme can effectively adsorb pollutants such as toluene and formaldehyde under indoor natural light or LED lighting without relying on ultraviolet lamps.

[0029] 2、The present application loads an ultrathin amorphous layer in the micropore region through a "micropore-mesopore-macropore" structure, retains a high specific surface area, uses F127 n-propanol solution soft film plates to construct mesopores and load nano TiO2 particles inside, and constructs macropores by spraying an ethanol suspension containing polystyrene microspheres, realizing a working mode of micropore adsorption of pollutants, mesopore photocatalytic degradation, and macropore rapid mass transfer and diffusion, and breaking through the bottleneck of single function and mutually exclusive performance of traditional materials through "adsorption-catalysis-mass transfer" synergy. DETAILED DESCRIPTION

[0030] The present application will be further described in detail below in conjunction with examples.

[0031] Example 1

[0032] A preparation method of a titanium-based modified honeycomb activated carbon composite, comprising the following steps:

[0033] S1: titanium tetrabutoxide, acetylacetone, and anhydrous ethanol are mixed in a molar ratio of 1:0.3:5, and 0.8wt% carbon nanotubes are added for ultrasonic stirring at 40℃ for 30min to obtain a titanium dioxide sol;

[0034] S2: honeycomb activated carbon is immersed in a sodium hydroxide solution at 60℃ for 1h, then washed with deionized water until neutral, and dried at 65℃ to obtain a substrate;

[0035] S3: the substrate is immersed in the titanium dioxide sol, and vacuum impregnation is performed at a vacuum degree of 0.02MPa for 2h;

[0036] S4: under nitrogen protection, the substrate after completion of impregnation in S3 is calcined at 250℃ for 2.5h to form an amorphous TiO2 layer; the nitrogen valve is closed, ammonia gas is introduced, and calcination is performed at 600℃ for 1.5h to generate nitrogen-doped TiO2:

[0037] S5: the substrate obtained after S4 is immersed in 3wt% F127 n-propanol solution for 30min, the F127 n-propanol solution is volatilized at 60℃, then a suspension of 20wt% polystyrene microspheres (particle size 200-500nm) in ethanol is sprayed, and the substrate is calcined at 450℃ for 3h under nitrogen protection to form through channels, thereby obtaining the titanium modified honeycomb activated carbon composite material.

[0038] Example 2

[0039] A method for preparing a titanium modified honeycomb activated carbon composite material, comprising the following steps:

[0040] S1: tetrabutyl titanate, acetylacetone, and anhydrous ethanol are mixed in a molar ratio of 1.5:0.5:5, and 0.9wt% carbon nanotubes are added to obtain a titanium dioxide sol by ultrasonic stirring at 45℃ for 30min;

[0041] S2: the honeycomb activated carbon is immersed in a potassium hydroxide solution at 70℃ for 1.5h, then washed with deionized water until neutral, and dried at 60℃ to obtain a substrate;

[0042] S3: the substrate is immersed in the titanium dioxide sol, and vacuum immersion is performed at a vacuum degree of 0.04MPa for 3h;

[0043] S4: the substrate after S3 is immersed is calcined at 300℃ for 2h under nitrogen protection to form an amorphous TiO2 layer; the nitrogen valve is closed, ammonia gas is introduced, and calcination is performed at 500℃ for 1.5h to generate nitrogen-doped TiO2:

[0044] S5: the substrate obtained after S4 is immersed in 5wt% F127 n-propanol solution for 40min, the F127 n-propanol solution is volatilized at 80℃, then a suspension of 25wt% polystyrene microspheres (particle size 200-500nm) in ethanol is sprayed, and the substrate is calcined at 500℃ for 2h under nitrogen protection to form through channels, thereby obtaining the titanium modified honeycomb activated carbon composite material.

[0045] Example 3

[0046] A method for preparing a titanium modified honeycomb activated carbon composite material, comprising the following steps:

[0047] S1: tetrabutyl titanate, acetylacetone, and anhydrous ethanol are mixed in a molar ratio of 1:0.2:5, and 0.9wt% carbon nanotubes are added to obtain a titanium dioxide sol by ultrasonic stirring at 45℃ for 30min;

[0048] S2: the honeycomb activated carbon is immersed in a potassium hydroxide solution at 70℃ for 1h, then washed with deionized water until neutral, and dried at 60℃ to obtain a substrate;

[0049] S3: immerse the substrate into the titanium dioxide sol, and immerse under negative pressure at a vacuum degree of 0.03 MPa for 3 h;

[0050] S4: calcine the substrate immersed in S3 under nitrogen protection at 250℃ for 2.5 h to form an amorphous TiO2 layer; close the nitrogen valve and introduce ammonia gas to calcine at 550℃ for 1.5 h to form nitrogen-doped TiO2;

[0051] S5: immerse the substrate calcined in S4 in 4wt% F127 n-propanol solution for 35 min, volatilize the F127 n-propanol solution at 70℃, then spray an ethanol suspension containing 23wt% polystyrene microspheres (200-500 nm in diameter), and calcine under nitrogen protection at 450℃ for 2.5 h to form through channels, thereby obtaining the titanium-based modified honeycomb activated carbon composite material.

[0052] Example 4

[0053] A method for preparing a titanium-based modified honeycomb activated carbon composite material, comprising the following steps:

[0054] S1: mix tetrabutyl titanate, acetylacetone and anhydrous ethanol according to a molar ratio of 1.3:0.4:5, and add 1wt% carbon nanotubes to obtain a titanium dioxide sol by ultrasonic stirring at 45℃ for 35 min;

[0055] S2: immerse the honeycomb activated carbon in a sodium hydroxide solution at 65℃ for 1 h, then wash with deionized water until neutral, and dry at 65℃ to obtain a substrate;

[0056] S3: immerse the substrate into the titanium dioxide sol, and immerse under negative pressure at a vacuum degree of 0.03 MPa for 2.5 h;

[0057] S4: calcine the substrate immersed in S3 under nitrogen protection at 300℃ for 2 h to form an amorphous TiO2 layer; close the nitrogen valve and introduce ammonia gas to calcine at 500℃ for 1.5 h to form nitrogen-doped TiO2;

[0058] S5: immerse the substrate calcined in S4 in 3wt% F127 n-propanol solution for 40 min, volatilize the F127 n-propanol solution at 60℃, then spray an ethanol suspension containing 20wt% polystyrene microspheres (200-500 nm in diameter), and calcine under nitrogen protection at 500℃ for 2 h to form through channels, thereby obtaining the titanium-based modified honeycomb activated carbon composite material.

[0059] Example 5

[0060] A method for preparing a titanium-based modified honeycomb activated carbon composite material, comprising the following steps:

[0061] S1: tetrabutyl titanate, acetylacetone, anhydrous ethanol were mixed in a molar ratio of 1:0.5:5, and 0.8wt% carbon nanotubes were added to the mixture, which was then stirred under ultrasonic at 45℃ for 35min to obtain a titanium dioxide sol;

[0062] S2: the honeycomb activated carbon was immersed in a sodium hydroxide solution at 65℃ for 1h, then washed with deionized water until neutral, and dried at 65℃ to obtain a substrate;

[0063] S3: the substrate was immersed in the titanium dioxide sol, and vacuum impregnation was carried out at a vacuum degree of 0.03MPa for 2.5h;

[0064] S4: the substrate after S3 impregnation was calcined at 300℃ for 2h under nitrogen protection, to form an amorphous TiO2 layer; the nitrogen valve was closed, and ammonia was introduced to calcine at 500℃ for 1.5h, to form nitrogen-doped TiO2:

[0065] S5: the substrate after S4 calcination was immersed in a 5wt% F127 n-propanol solution for 40min, the F127 n-propanol solution was volatilized at 60℃, then an ethanol suspension containing 25wt% polystyrene microspheres (particle size 200-500nm) was sprayed, and calcination was carried out at 500℃ for 2h under nitrogen protection to form through channels, thereby obtaining a titanium-modified honeycomb activated carbon composite material.

[0066] Comparative Example 1 used a traditional impregnation method

[0067] First step: consistent with Example S1;

[0068] Second step: consistent with Example S2, except that the immersion time was 6h;

[0069] Third step: the substrate obtained in the second step was placed in a muffle furnace under air atmosphere, heated to 450℃ at a rate of 5℃ / min, and calcined at constant temperature for 3h, then naturally cooled to room temperature, thereby obtaining a TiO2 / activated carbon composite material.

[0070] Comparative Example 2 without nitrogen doping

[0071] Consistent with Example 1, except that no staged calcination was carried out in S4, and calcination was carried out only under nitrogen protection without introducing ammonia.

[0072] Comparative Example 3 without mesopore formation and reduced nano-TiO2 particle loading

[0073] Consistent with Example 1, except that the F127 n-propanol solution immersion was omitted in S5, and the ethanol suspension containing polystyrene microspheres was directly sprayed.

[0074] In order to verify that the titanium-modified honeycomb activated carbon composite material provided by the present application has excellent adsorption performance and a high specific surface area, the examples and comparative examples were tested.

[0075] Adsorption performance test: the titanium modified honeycomb activated carbon composite material prepared by the examples and the comparative examples is placed in a closed device containing pollutants, the pollutants in the device are gas containing formaldehyde and total suspended particulate, the same device is placed in ultraviolet light and indoor natural light respectively, the pollutant content in the device is detected after 2h; specific surface area test: the BET specific surface area of the material is tested by nitrogen adsorption isotherm method, as shown in Table 1.

[0076] Table 1

[0077]

[0078] Through the comparison of pollutant absorption experiments of examples and comparative examples under different light and specific surface area test, it can be seen that the titanium modified honeycomb activated carbon composite material provided by the examples has a formaldehyde purification efficiency of more than 97% and a total suspended particulate absorption rate of more than 98% under ultraviolet light or natural light, which is far superior to the comparative examples, and the specific surface area is also more than 1320m 2 / g.

[0079] In combination with the comparative examples, the comparative example 1 uses the traditional impregnation method to uniformly load the titanium precursor on the surface of the activated carbon, the specific surface area of the material is greatly reduced, and the purification efficiency of formaldehyde is also much lower than that of the examples; the honeycomb activated carbon obtained by the comparative example 2 without section calcination has poor adaptability to LED light source, and the formaldehyde purification efficiency under indoor light source is obviously lower than that of other groups; and the comparative example 3 does not use F127 n-propanol solution, and does not form a penetrating mesoporous network in the activated carbon, so as to load nano TiO2 particles, resulting in a great discount of the formaldehyde purification efficiency and the suspended particulate absorption rate.

[0080] The above only describes some embodiments of the present application. For those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application.

Claims

1. A method for producing a titanium-modified honeycomb activated carbon composite material, characterized by comprising: a step of mixing a titanium compound and a honeycomb activated carbon; and a step of heating the mixture to a temperature of 400 to 800°C in an inert gas atmosphere. It comprises the following steps: S1: mixing tetrabutyl titanate, acetylacetone and anhydrous ethanol according to a molar ratio of 1-1.5:0.2-0.5:5, adding a dispersant to obtain a titanium dioxide sol; the dispersant is carbon nanotubes with a concentration of 0.8-1wt%; S2: immersing the honeycomb activated carbon in an alkali solution, washing and drying to obtain a substrate; S3: immersing the substrate in the titanium dioxide sol and vacuum negative pressure immersion; S4: calcining the substrate immersed in S3 under the conditions of passing inert gas and 250-300℃ for 2-3h to form an amorphous TiO2 layer; then calcining under the conditions of passing ammonia and 500-600℃ for 1-1.5h to generate nitrogen-doped TiO2; S5: immersing the substrate obtained after calcination in S4 in F127 n-propanol solution, spraying an ethanol suspension containing polystyrene microspheres after volatilizing the F127 n-propanol solution, and calcining in inert gas at 450-500℃ for 2-3h to form through channels, thereby obtaining the titanium-modified honeycomb activated carbon composite material.

2. The method for producing a titanium-modified honeycomb activated carbon composite material according to claim 1, characterized by, In S1, after adding the dispersant, ultrasonic stirring is performed at 40-50℃ for 30-35min.

3. The method for producing a titanium-modified honeycomb activated carbon composite material according to claim 1, characterized by, In S2, the immersion time is 1-1.5h and the immersion temperature is 60-70℃; the washing step specifically comprises washing with deionized water until neutral, and the drying temperature is 60-65℃.

4. The method for producing a titanium-modified honeycomb activated carbon composite material according to claim 3, characterized by, The alkali solution is a sodium hydroxide solution or a potassium hydroxide solution.

5. The method for producing a titanium-modified honeycomb activated carbon composite material according to claim 1, characterized by, In S3, the vacuum degree is 0.02-0.04MPa and the immersion time is 2-3h.

6. The method for producing a titanium-modified honeycomb activated carbon composite material according to claim 1, characterized by, In S5, the concentration of the F127 n-propanol solution is 3-5wt%, the immersion time is 30-40min, and the volatilization temperature is 60-80℃.

7. The method for producing a titanium-modified honeycomb activated carbon composite material according to claim 6, characterized by, The polystyrene microspheres have a particle size of 200-500nm, and the mass percentage of polystyrene microspheres in the ethanol suspension is 20-25%.

8. A titanium-modified honeycomb activated carbon composite material prepared by the preparation method according to any one of claims 1-7.

9. Use of the titanium-modified honeycomb activated carbon composite material according to claim 8 in the field of adsorption materials.

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