Titanium modified honeycomb activated carbon composite material as well as preparation method and application thereof

Abstract

The invention 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. The titanium modified honeycomb activated carbon composite material is prepared by the following steps: mixing tetrabutyl titanate, acetylacetone and absolute ethyl alcohol, adding a dispersing agent, and stirring to obtain titanium dioxide sol; dipping honeycomb active carbon in an alkali solution, washing and drying to obtain a substrate; immersing the matrix into the sol for vacuum negative pressure impregnation; inert gas is introduced to calcine the matrix, and an amorphous TiO2 layer is formed; the preparation method comprises the following steps of: soaking a calcined matrix in an F127 normal propyl alcohol solution, spraying an ethanol suspension containing polystyrene microspheres after the F127 normal propyl alcohol solution is volatilized, and calcining in inert gas to form a through pore channel. The composite material provided by the invention 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 present invention belongs to the technical field of honeycomb activated carbon production, and in particular relates to a titanium-modified honeycomb activated carbon composite material, a preparation method thereof, and an application thereof. Background Art

[0002] As a 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 (capture of benzene series and hydrogen sulfide), medical protection (mask filter elements) 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, magnetic response and other properties through metal / metal oxide modification to form bifunctional composite materials. However, although the existing commercially available honeycomb activated carbon has the advantage of molding, it still has problems such as low adsorption capacity, single function, and poor moisture resistance. Traditional modification technologies (such as TiO2 loading) easily clog its original pores, resulting in a decrease in specific surface area, and insufficient mechanical strength, making it difficult to meet the needs of complex working conditions and difficult to take into account adsorption capacity, high-efficiency catalytic activity and engineering applicability. Summary of the Invention

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

[0005] The first aspect of the present invention is to provide a method for preparing a titanium-modified honeycomb activated carbon composite material, comprising the following steps:

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

[0007] S2: Immersing the honeycomb activated carbon in an alkaline solution, washing and drying it to obtain a matrix;

[0008] S3: Immersing the substrate into the titanium dioxide sol under vacuum and negative pressure;

[0009] S4: calcining the substrate impregnated in S3 under the condition of passing inert gas to form an amorphous TiO2 layer; and then calcining under the condition of passing ammonia to generate nitrogen-doped TiO2:

[0010] S5: The matrix obtained after calcination in S4 is impregnated with F127 n-propanol solution. After the F127 n-propanol solution evaporates, an ethanol suspension containing polystyrene microspheres is sprayed on the matrix. The matrix is calcined in an inert gas to form through pores, thereby obtaining a titanium-modified honeycomb activated carbon composite material.

[0011] It should be noted that acetylacetone as a chelating agent can 4+ The formation of a stable complex inhibits the rapid hydrolysis of titanate and prevents the coagulation of the sol, thereby ensuring the uniformity of the sol. The complex decomposes to form an amorphous TiO2 layer. The ultra-thin amorphous TiO2 layer can be loaded on the surface of the honeycomb activated carbon to avoid clogging the micropores of the honeycomb activated carbon, so that the honeycomb activated carbon always maintains a high specific surface area and improves the adsorption capacity and adsorption ability.

[0012] In some embodiments, after adding a dispersant to S1, ultrasonic stirring is performed at 40-50° C. for 30-35 minutes; the dispersant is carbon nanotubes with a concentration of 0.8-1 wt %.

[0013] It should be noted that the surface of the carbon nanotube dispersant is rich in functional groups, which can prevent the aggregation of nano-TiO2 particles through electrostatic repulsion and steric hindrance effects, control the particle size of nano-TiO2 within an appropriate range, and improve the conductivity of the material.

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

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

[0016] The present invention immerses the honeycomb activated carbon in an alkaline solution, uses the alkaline solution to corrode the wall pores, and expands the micropores to mesopores. The micropores have large molecular diffusion resistance and are easily clogged by large molecules or high-flow gases. The presence of mesopores can reduce the diffusion resistance, speed up the material transmission speed, reduce the pore blockage caused by the retention of pollutants, and improve the overall treatment efficiency.

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

[0018] In some embodiments, in S4, an inert gas is introduced and the calcination is carried out at 250-300° C. for 2-3 h, and ammonia is introduced and the calcination is carried out at 500-600° C. for 1-1.5 h.

[0019] The present invention increases the penetration depth of the sol and improves the uniformity of the internal titanium load through vacuum negative pressure impregnation; through segmented calcination, inert gas is used for calcination to avoid the reaction of activated carbon with oxygen at high temperature to form an amorphous TiO2 layer, prevent the matrix from collapsing and the loss of specific surface area, and retain the highly active surface; then ammonia is introduced for calcination, and NH3 molecules are preferentially adsorbed on the oxygen vacancies on the TiO2 surface. At high temperature, the NH3 adsorbed on the surface dissociates to generate NH2 - and H + , NH2 -The nitrogen atoms in the honeycomb replace some of the oxygen atoms in TiO2 to form an N-TiO2 structure, which reduces the band gap of N-doped TiO2 and expands the light absorption range from only absorbing ultraviolet light to the visible light region. It can greatly improve the degradation rate of honeycomb activated carbon for pollutants (such as toluene, formaldehyde, tetracycline, etc.), and at the same time reduce 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 3-5 wt %, the impregnation time is 30-40 min, the volatilization temperature is 60-80° C., the calcination temperature is 450-500° C., and the calcination time is 2-3 h.

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

[0022] It should be noted that the present invention impregnates the substrate with an n-propanol solution of Pluronic F127 (i.e., a solution formed by dissolving Pluronic F127 in n-propanol). Pluronic F127 is a polyoxyethylene-polyoxypropylene block copolymer that self-assembles into micelles in solution, guiding the formation of mesopores. The n-propanol is used to dissolve the F127 and volatilizes at 60-80°C, where the micelles are fixed to the inner walls of the pores, forming a pore structure. A concentration of 3-5wt% of F127 in n-propanol reaches the critical concentration for micelle formation. At this concentration, the micelles are spaced appropriately apart, forming a permeable mesoporous network. The mesopores are loaded with nano-TiO2 particles, providing space for catalytic reactions and optimizing mass transfer pathways.

[0023] In addition, the present invention sprays an ethanol suspension containing polystyrene microspheres. The polystyrene microspheres are decomposed when calcined at high temperature to generate gaseous products, which form pores in the honeycomb activated carbon, leaving cavities to form macropores, thereby constructing a through-hole macroporous structure in the material, which can improve the flow and diffusion of fluids. At the same time, an inert gas is introduced when the polystyrene microspheres are calcined at high temperature. The purpose is to prevent the polystyrene microspheres from burning violently, isolating oxygen so that the polystyrene microspheres are pyrolyzed at high temperature rather than burned. In the presence of oxygen, the intense heat release will cause a sudden increase in local temperature, destroying the activated carbon pore structure and even causing the carbon skeleton of the material to collapse.

[0024] The second aspect of the present invention is to provide a titanium-modified honeycomb activated carbon composite material.

[0025] The third aspect of the present invention is to provide an application of a titanium-modified honeycomb activated carbon composite material in the field of adsorption materials.

[0026] The titanium-modified honeycomb activated carbon composite material provided by the present invention can be applied to fields such as air purification, industrial waste gas treatment, and water body restoration.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention loads an ultra-thin amorphous TiO2 layer on the surface of honeycomb activated carbon through vacuum impregnation and segmented calcination, covering the pore surface but not blocking the pores, retaining a high specific surface area, providing high catalytic active sites, and improving mass transfer efficiency. The N-TiO2 structure is formed by calcination with ammonia, which expands the light absorption range. The titanium-modified honeycomb activated carbon composite material provided by this technical solution does not need to rely on ultraviolet lamps and can effectively adsorb pollutants such as toluene and formaldehyde under indoor natural light or LED lighting.

[0029] 2. The present invention adopts a "micropore-mesopore-macroporous" structure, loads an ultra-thin amorphous layer in the micropore area, retains a high specific surface area, uses F127 n-propanol solution soft film to construct mesopores and load nano-TiO2 particles inside, and constructs macropores by spraying an ethanol suspension containing polystyrene microspheres. This realizes a working mode of micropore adsorption of pollutants, mesopore photocatalytic degradation, and macropore rapid mass transfer and diffusion. Through the synergistic "adsorption-catalysis-mass transfer", it breaks through the bottleneck of traditional materials with single functions and mutually exclusive performances. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to the embodiments.

[0031] Example 1

[0032] A method for preparing a titanium-modified honeycomb activated carbon composite material comprises the following steps:

[0033] S1: Tetrabutyl titanate, acetylacetone, and anhydrous ethanol were mixed in a molar ratio of 1:0.3:5, and carbon nanotubes with a concentration of 0.8 wt% were added and ultrasonically stirred at 40°C for 30 min to obtain a titanium dioxide sol;

[0034] S2: The honeycomb activated carbon was immersed in a sodium hydroxide solution at 60°C for 1 hour, then washed with deionized water until neutral, and dried at 65°C to obtain a matrix;

[0035] S3: Immerse the substrate in titanium dioxide sol and immerse it under negative pressure at a vacuum degree of 0.02 MPa for 2 h;

[0036] S4: Under nitrogen protection, the substrate impregnated in S3 was calcined at 250°C for 2.5 hours to form an amorphous TiO2 layer; the nitrogen valve was closed, and ammonia was introduced and calcined at 600°C for 1.5 hours to generate nitrogen-doped TiO2:

[0037] S5: The matrix obtained after calcination in S4 was impregnated with 3wt% F127 n-propanol solution for 30 minutes. The F127 n-propanol solution was evaporated at 60°C, and then sprayed with an ethanol suspension containing 20wt% polystyrene microspheres (particle size 200-500nm). The matrix was calcined at 450°C for 3 hours under nitrogen protection to form through channels, thereby obtaining a titanium-modified honeycomb activated carbon composite material.

[0038] Example 2

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

[0040] S1: Tetrabutyl titanate, acetylacetone, and anhydrous ethanol were mixed in a molar ratio of 1.5:0.5:5, and carbon nanotubes with a concentration of 1 wt% were added and ultrasonically stirred at 50°C for 35 min to obtain a titanium dioxide sol;

[0041] S2: The honeycomb activated carbon was immersed in a potassium hydroxide solution at 70°C for 1.5 hours, then washed with deionized water until neutral, and dried at 60°C to obtain a matrix;

[0042] S3: Immerse the substrate in titanium dioxide sol and immerse it under negative pressure at a vacuum degree of 0.04 MPa for 3 hours;

[0043] S4: Under nitrogen protection, the substrate impregnated in S3 was calcined at 300°C for 2 hours to form an amorphous TiO2 layer; the nitrogen valve was closed, and ammonia was introduced and calcined at 500°C for 1.5 hours to generate nitrogen-doped TiO2:

[0044] S5: The matrix obtained after calcination in S4 was impregnated with 5wt% F127 n-propanol solution for 40 minutes. The F127 n-propanol solution was evaporated at 80°C, and then sprayed with an ethanol suspension containing 25wt% polystyrene microspheres (particle size 200-500nm). The matrix was calcined at 500°C for 2 hours under nitrogen protection to form through channels, thereby obtaining a titanium-modified honeycomb activated carbon composite material.

[0045] Example 3

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

[0047] S1: Tetrabutyl titanate, acetylacetone, and anhydrous ethanol were mixed in a molar ratio of 1:0.2:5, and carbon nanotubes with a concentration of 0.9 wt% were added and ultrasonically stirred at 45 °C for 30 min to obtain a titanium dioxide sol;

[0048] S2: The honeycomb activated carbon was immersed in a potassium hydroxide solution at 70°C for 1 hour, then washed with deionized water until neutral, and dried at 60°C to obtain a matrix;

[0049] S3: Immerse the substrate in titanium dioxide sol and immerse it under negative pressure at a vacuum degree of 0.03 MPa for 3 hours;

[0050] S4: Under nitrogen protection, the substrate impregnated in S3 was calcined at 250°C for 2.5 hours to form an amorphous TiO2 layer; the nitrogen valve was closed, and ammonia was introduced and calcined at 550°C for 1.5 hours to generate nitrogen-doped TiO2:

[0051] S5: The substrate obtained after calcination in S4 was impregnated with 4 wt% F127 n-propanol solution for 35 minutes. The F127 n-propanol solution was evaporated at 70°C, and then sprayed with an ethanol suspension containing 23 wt% polystyrene microspheres (particle size 200-500 nm). The substrate was calcined at 450°C for 2.5 hours under nitrogen protection to form through channels, thereby obtaining a titanium-modified honeycomb activated carbon composite material.

[0052] Example 4

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

[0054] S1: Tetrabutyl titanate, acetylacetone, and anhydrous ethanol were mixed in a molar ratio of 1.3:0.4:5, and carbon nanotubes with a concentration of 1 wt% were added and ultrasonically stirred at 45°C for 35 min to obtain a titanium dioxide sol;

[0055] S2: The honeycomb activated carbon was immersed in a sodium hydroxide solution at 65°C for 1 hour, then washed with deionized water until neutral, and dried at 65°C to obtain a matrix;

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

[0057] S4: Under nitrogen protection, the substrate impregnated in S3 was calcined at 300°C for 2 hours to form an amorphous TiO2 layer; the nitrogen valve was closed, and ammonia was introduced and calcined at 500°C for 1.5 hours to generate nitrogen-doped TiO2:

[0058] S5: The substrate obtained after calcination in S4 was impregnated with 3 wt% F127 n-propanol solution for 40 min. The F127 n-propanol solution was evaporated at 60°C, and then sprayed with an ethanol suspension containing 20 wt% polystyrene microspheres (particle size 200-500 nm). The substrate was calcined at 500°C for 2 h under nitrogen protection to form through channels, thereby obtaining a titanium-modified honeycomb activated carbon composite material.

[0059] Example 5

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

[0061] S1: Tetrabutyl titanate, acetylacetone, and anhydrous ethanol were mixed in a molar ratio of 1:0.5:5, and carbon nanotubes with a concentration of 0.8 wt% were added and ultrasonically stirred at 45 °C for 35 min to obtain a titanium dioxide sol;

[0062] S2: The honeycomb activated carbon was immersed in a sodium hydroxide solution at 65°C for 1 hour, then washed with deionized water until neutral, and dried at 65°C to obtain a matrix;

[0063] S3: Immerse the substrate in titanium dioxide sol and immerse it under negative pressure at a vacuum degree of 0.03 MPa for 2.5 h;

[0064] S4: Under nitrogen protection, the substrate impregnated in S3 was calcined at 300°C for 2 hours to form an amorphous TiO2 layer; the nitrogen valve was closed, and ammonia was introduced and calcined at 500°C for 1.5 hours to generate nitrogen-doped TiO2:

[0065] S5: The matrix obtained after calcination in S4 was impregnated with 5wt% F127 n-propanol solution for 40 minutes. The F127 n-propanol solution was evaporated at 60°C, and then sprayed with an ethanol suspension containing 25wt% polystyrene microspheres (particle size 200-500nm). The matrix was calcined at 500°C for 2 hours under nitrogen protection to form through channels, thereby obtaining a titanium-modified honeycomb activated carbon composite material.

[0066] Comparative Example 1: Traditional dipping method

[0067] The first step is the same as in Example S1;

[0068] Step 2: The same as Example S2, except that the immersion time is 6 hours;

[0069] Step 3: Place the substrate obtained in the second step in a muffle furnace under air atmosphere and heat it to 450°C at 5°C / min, calcine at constant temperature for 3 hours, and cool it naturally to room temperature to obtain a TiO2 / activated carbon composite material.

[0070] Comparative Example 2: No nitrogen doping

[0071] The process is consistent with Example 1, except that in S4, no staged calcination is performed, and calcination is performed only under nitrogen protection without introducing ammonia.

[0072] Comparative Example 3 does not form mesopores and reduces the loading of nano-TiO2 particles

[0073] The same as Example 1, the only difference is that the immersion in the F127 n-propanol solution is omitted in S5, and the ethanol suspension containing polystyrene microspheres is directly sprayed.

[0074] In order to verify that the titanium-modified honeycomb activated carbon composite material provided by the present invention 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 materials prepared in the examples and comparative examples were placed in a closed device containing pollutants. The pollutants in the device were gases containing formaldehyde and total suspended particulate matter. The same device was placed under ultraviolet light and indoor natural light, respectively. The pollutant content in the device was detected after 2 hours. Specific surface area test: The BET specific surface area of the material was tested using the nitrogen adsorption isotherm method, as shown in Table 1.

[0076] Table 1

[0077]

[0078] By comparing the absorption experiments of pollutants under different light and the specific surface area test of the embodiment and the comparative example, it can be seen that the titanium modified honeycomb activated carbon composite material provided by the embodiment of the present invention has a formaldehyde purification efficiency of more than 97% under both ultraviolet light and natural light, and the total suspended particulate matter absorption rate is more than 98%, which is much better than the comparative example, and the specific surface area is also 1320m 2 / g or above.

[0079] In combination with the comparative examples, comparative example 1 adopts 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 formaldehyde purification efficiency is also far lower than that of the embodiment; the honeycomb activated carbon obtained by comparative example 2 without segmented calcination has poor adaptability to LED light sources, and the formaldehyde purification efficiency under indoor light sources is significantly lower than that of other groups; and comparative example 3 does not use F127 n-propanol solution, and no through-mesoporous network is formed in the activated carbon, so that nano-TiO2 particles cannot be loaded, resulting in a significant reduction in the formaldehyde purification efficiency and the absorption rate of suspended particulate matter.

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

Claims

1. A method for preparing a titanium modified honeycomb activated carbon composite material, characterized in that: The following steps are involved: S1: Tetrabutyl titanate, acetylacetone, and anhydrous ethanol are mixed in a molar ratio of 1-1.5:0.2-0.5:5, and a dispersant is added and stirred to obtain a titanium dioxide sol; S2: Immersing the honeycomb activated carbon in an alkaline solution, washing and drying to obtain a matrix; S3: Immersing the substrate in the titanium dioxide sol under vacuum negative pressure; S4: calcining the substrate impregnated in S3 under the condition of passing inert gas to form an amorphous TiO2 layer; and then calcining under the condition of passing ammonia to generate nitrogen-doped TiO2: S5: impregnating the substrate obtained after calcination in S4 with F127 n-propanol solution, spraying an ethanol suspension containing polystyrene microspheres after volatilization of the F127 n-propanol solution, and calcining in an inert gas to form through channels, thereby obtaining the titanium-modified honeycomb activated carbon composite material.

2. The method for preparing the titanium modified honeycomb activated carbon composite material according to claim 1, characterized in that: In the above S1, after adding the dispersant, ultrasonic stirring is carried out at 40-50° C. for 30-35 minutes; the dispersant is carbon nanotubes with a concentration of 0.8-1 wt%.

3. The method for preparing the titanium modified honeycomb activated carbon composite material according to claim 1, characterized in that: In the step S2, the immersion time is 1-1.5 hours, the immersion temperature is 60-70°C, the washing step is specifically washing with deionized water until neutral, and the drying temperature is 60-65°C.

4. The method for preparing the titanium modified honeycomb activated carbon composite material according to claim 3, characterized in that: The alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution.

5. The method for preparing the titanium modified honeycomb activated carbon composite material according to claim 1, characterized in that: In the S3, the vacuum degree is 0.02-0.04 MPa, and the immersion time is 2-3 hours.

6. The method for preparing the titanium modified honeycomb activated carbon composite material according to claim 1, characterized in that: In the step S4, an inert gas is introduced and the mixture is calcined at 250-300° C. for 2-3 hours, and ammonia is introduced and the mixture is calcined at 500-600° C. for 1-1.5 hours.

7. The method for preparing the titanium modified honeycomb activated carbon composite material according to claim 1, characterized in that: In the S5, the concentration of the F127 n-propanol solution is 3-5 wt %, the immersion time is 30-40 min, the volatilization temperature is 60-80° C., the calcination temperature is 450-500° C., and the calcination time is 2-3 h.

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

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

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

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