A honeycomb-shaped activated carbon for solvent recovery and its preparation method

Abstract

The present invention relates to a honeycomb-shaped activated carbon for solvent recovery and a preparation method thereof, belonging to the technical field of activated carbon. The preparation method comprises the following steps: S1. Take bamboo, wash, dry and sterilize it to obtain clean raw materials; S2. After heating and raising the temperature, add a carbon body, start a vacuum pump to control the pressure, after heat preservation and pressure maintenance treatment, cool to room temperature and then pulverize it, and at the same time spray with an acidic solution, after solid-liquid separation, obtain a mixed material; S3. Grind it into powder by ball milling, screen the mixed material after ball milling to obtain a mixed powder; S4. Add an acid solution and mix and stir, activate it in a water vapor atmosphere, and after cooling, obtain an activated product; S5. Wash and filter, take the solid matter and dry it to obtain activated carbon. The use of a water vapor atmosphere is beneficial to the formation of mesopores in the activated carbon during the phosphoric acid activation process. Combining with the added microporous activated carbon can overcome the defects of pore structure collapse and yield decline caused by over-activation.

Description

Technical Field

[0001] The present invention belongs to the technical field of activated carbon, and relates to a honeycomb solvent recovery activated carbon and a preparation method thereof. Background Art

[0002] Solvent recovery activated carbon generally refers to activated carbon for organic solvent recovery, which is mainly used for high-end air purification or various gas solvent recoveries. Currently, coal-based granular carbon, coal-based columnar carbon, and coconut shell granular carbon are mostly used. Coal is a non-renewable resource. The demand for wood-based activated carbon is increasing continuously, but the trees for producing charcoal grow very slowly. To alleviate the contradiction between charcoal demand and ecological resource protection, bamboo activated carbon produced by burning bamboo combined with chemical activation method can be used to prepare activated carbon. However, the traditional use of phosphoric acid activation method has problems such as too long reaction time and low efficiency. The main reason is that the binding force in bamboo is high, the structure is stable and not easily damaged. Some studies have shown that by comparing the preparation of activated carbon by activating hemp stalks with phosphoric acid in N2 and H2O atmospheres, the steam atmosphere is more conducive to the formation of mesopores during the phosphoric acid activation process, and the specific surface area reaches 2500m 2 / g, and the micropore volume can reach 0.89cm 3 / g, and the mesopore pore volume can reach 1.80cm 3 / g. Although the activated carbon prepared by this method can combine the advantages of different activation methods of steam and phosphoric acid activation, it also has corresponding disadvantages that cannot be overcome, such as the collapse of the pore structure caused by over-activation, energy waste, complex steps, and the decrease in yield. Summary of the Invention

[0003] The purpose of the present invention is to provide a honeycomb solvent recovery activated carbon and a preparation method thereof, which adopt a steam atmosphere to be conducive to the formation of mesopores during the phosphoric acid activation process, and combine with the added microporous activated carbon to overcome the defects of the collapse of the pore structure and the decrease in yield caused by over-activation.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] A honeycomb solvent recovery activated carbon, and the preparation method of the activated carbon includes the following steps:

[0006] S1. Take bamboo, perform ultrasonic cleaning, dry and sterilize it to obtain clean raw materials;

[0007] S2. Heat and raise the temperature of the clean raw materials, add a carbon body, start a vacuum pump to control the pressure, perform heat preservation and pressure maintenance treatment, cool to room temperature and then crush, and at the same time spray with an acidic solution, and after solid-liquid separation, obtain a mixed material;

[0008] S3. Grind the mixed material into powder, screen the mixed material after ball milling to obtain a mixed powder;

[0009] S4. Add acid solution to the mixed powder, mix and stir, and activate it under a steam atmosphere. After cooling, an activated product is obtained;

[0010] S5. Take the activated product for washing and filtering, and take the solid for drying to obtain activated carbon.

[0011] As a preferred technical solution of the present invention, in step S1, the conditions for ultrasonic cleaning are to place the bamboo in distilled water and perform ultrasonic cleaning for 30 - 45 min; the conditions for drying are to dry in an oven at 75 - 80 °C for 8 - 10 h; the conditions for sterilization are to use ultraviolet irradiation for sterilization.

[0012] As a preferred technical solution of the present invention, in step S2, the conditions for heating and raising the temperature are to heat to 90 - 95 °C; the time for heat preservation and pressure maintenance treatment is 30 - 45 min.

[0013] As a preferred technical solution of the present invention, in step S2, the mass ratio of the clean raw material to the carbon body is 10:1 - 1.5, and the carbon body is microporous activated carbon. Among them, the micropore diameter of the microporous activated carbon is <2 nm, and the micropore volume ratio is 75 - 80%; the conditions for controlling the pressure are to adjust the pressure to 0.01 - 0.05 pa; the acidic solution is a phosphoric acid solution with a concentration of 7 - 10 mol / L; adding microporous activated carbon can rapidly reduce the bonding strength of the bamboo in the state of overloading carbon with added microporous activated carbon and make it easy to crush. By combining with spraying the phosphoric acid solution and spraying in a small amount and intermittently, the crushing efficiency can be greatly improved, and it is more energy-saving and the cost is reduced; during this process, using the phosphoric acid solution can also pre-activate the bamboo raw material; the micropore diameter of the added microporous activated carbon is <2 nm, and the micropore volume ratio is 75 - 80%, which is dissolved in the activated carbon with a rich microporous structure, greatly increasing the contact area between the phosphoric acid solution activator and the activated carbon raw material in the subsequent activation process, greatly improving the activation efficiency, and these microporous structures are all activated into mesoporous or macroporous structures in the later stage.

[0014] As a preferred technical solution of the present invention, in step S3, the conditions for ball milling are at a rotation speed of 200 - 300 r / min and a ball milling time of 1 - 1.5 h; the conditions for screening are to pass through an 80-mesh sieve.

[0015] As a preferred technical solution of the present invention, in step S4, the mass ratio of the mixed powder to the acid solution is 1:3.5 - 4.0, and the conditions for cooling are to cool to room temperature.

[0016] As a preferred technical solution of the present invention, in step S4, the acid solution is a phosphoric acid solution with a concentration of 10-11 mol / L; the activation conditions are as follows: the heating rate is 6-8 °C / min, the temperature is heated to 520-550 °C, and the activation time is 60-70 min. The solution of the present invention is conducive to the formation of mesopores during the phosphoric acid activation process by adopting a water vapor atmosphere. Combining with the microporous activated carbon added in the above steps, it is beneficial to the activation process and reduces the impact on the surface of the raw material. The microporous activated carbon penetrates into the structure of the raw material, fills the over-large pores, and overcomes the defects of pore structure collapse and yield reduction caused by over-activation. Among them, the water vapor atmosphere adopted in the examples and comparative examples of the present invention is to disconnect nitrogen in a nitrogen atmosphere and introduce water vapor at a rate of 5 mL / min under a pressure of 0.4 MPa.

[0017] As a preferred technical solution of the present invention, in step S5, the cleaning conditions are to clean with deionized water until the pH value of the cleaning solution is neutral; the drying conditions are to dry at 105-110 °C for 5.5-6.0 h.

[0018] As a preferred technical solution of the present invention, activated carbon prepared by the preparation method of the above-mentioned honeycomb-shaped solvent recovery activated carbon is applied to solvent recovery; among them, the pore diameter of the macropores of the activated carbon prepared by the present invention is >50 nm, the pore diameter of the mesopores is 2-50 nm, and the pore diameter of the micropores is <2 nm.

[0019] The beneficial effects of the present invention:

[0020] (1) The solution of the present invention is conducive to the formation of mesopores during the phosphoric acid activation process by adopting a water vapor atmosphere. Combining with the added microporous activated carbon, it is beneficial to the activation process and reduces the impact on the surface of the raw material. The microporous activated carbon penetrates into the structure of the raw material, fills the over-large pores, and overcomes the defects of pore structure collapse and yield reduction caused by over-activation.

[0021] (2) By adding microporous activated carbon, the bonding strength of bamboo rapidly decreases in the state of overloaded carbon with added microporous activated carbon and is easy to crush. By combining with spraying a phosphoric acid solution in a small intermittent spraying manner, the crushing efficiency can be greatly improved. At the same time, using the phosphoric acid solution can also pre-activate the bamboo raw material.

[0022] (3) The micropore diameter of the added microporous activated carbon is <2 nm, and the micropore volume ratio is 75-80%. It is dissolved in the activated carbon with a rich microporous structure, greatly increasing the contact area between the phosphoric acid solution activator and the activated carbon raw material in the subsequent activation process, greatly improving the activation efficiency, and these microporous structures are all activated into mesopore or macropore structures in the later stage. Detailed implementation mode

[0023] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following will, in conjunction with embodiments, elaborate in detail on the specific implementation manners, structures, features and their effects of the present invention as follows.

[0024] Example 1

[0025] A preparation method of honeycomb-shaped activated carbon for solvent recovery includes the following steps:

[0026] S1. Take bamboo, perform ultrasonic cleaning, drying and sterilization to obtain clean raw materials. Among them, the conditions for ultrasonic cleaning are to place the bamboo in distilled water and perform ultrasonic cleaning for 30 minutes; the conditions for drying are to dry in an oven at 75°C for 10 hours; the conditions for sterilization are to use ultraviolet irradiation for sterilization.

[0027] S2. Heat up the clean raw materials and add carbon bodies, start the vacuum pump for pressure control, after heat preservation and pressure maintenance treatment, cool to room temperature and then crush, and at the same time spray with an acidic solution, and after solid-liquid separation, obtain a mixed material. Among them, the mass ratio of the clean raw materials to the carbon bodies is 10:1, the carbon bodies are microporous activated carbon, among which, the micropore diameter of the microporous activated carbon is <2 nm, and the micropore volume ratio is 75%; the conditions for pressure control are to adjust the pressure to 0.01 pa; the acidic solution is a phosphoric acid solution with a concentration of 7 mol / L; the conditions for heating up are to heat to 90°C; the time for heat preservation and pressure maintenance treatment is 45 minutes.

[0028] S3. Ball-mill the mixed material into powder, screen the ball-milled mixed material to obtain a mixed powder. Among them, the conditions for ball-milling are to ball-mill at a rotation speed of 200 r / min for 1.5 hours; the conditions for screening are to pass through an 80-mesh sieve.

[0029] S4. Add acid solution to the mixed powder and mix and stir, and perform activation in a water vapor atmosphere. After cooling, obtain an activated product. Among them, the mass ratio of the mixed powder to the acid solution is 1:3.5, the acid solution is a phosphoric acid solution with a concentration of 10 mol / L; the conditions for activation are to heat at a heating rate of 6°C / min, heat to 520°C, and activate for 70 minutes.

[0030] S5. Take the activated product for cleaning and filtration, take the solid matter for drying, and obtain activated carbon. Among them, the conditions for cleaning are to clean with deionized water until the pH value of the cleaning solution is neutral; the conditions for drying are to dry at a temperature of 105°C for 6.0 hours.

[0031] Example 2

[0032] A preparation method of honeycomb-shaped activated carbon for solvent recovery includes the following steps:

[0033] S1. Take bamboo, conduct ultrasonic cleaning, dry and sterilize it to obtain clean raw materials. Among them, the conditions for ultrasonic cleaning are to place the bamboo in distilled water and conduct ultrasonic cleaning for 38 minutes; the conditions for drying are to dry in an oven at 78 °C for 9 hours; the conditions for sterilization are to use ultraviolet irradiation for sterilization.

[0034] S2. Heat up the clean raw materials and add carbon bodies, start the vacuum pump to control the pressure, after heat preservation and pressure maintenance treatment, cool to room temperature and then crush, and at the same time spray with an acidic solution. After solid-liquid separation, obtain a mixed material. Among them, the mass ratio of the clean raw materials to the carbon bodies is 10:1.2, the carbon bodies are microporous activated carbons, among which, the micropore diameter of the microporous activated carbon is <2 nm, and the micropore volume ratio is 78%; the conditions for pressure control are to adjust the pressure to 0.03 pa; the acidic solution is a phosphoric acid solution with a concentration of 8.5 mol / L; the conditions for heating and temperature rise are to heat to 92.5 °C; the time for heat preservation and pressure maintenance treatment is 38 minutes.

[0035] S3. Grind the mixed material into powder, screen the mixed material after grinding to obtain a mixed powder. Among them, the conditions for grinding are to grind at a rotation speed of 250 r / min for 1.25 hours; the conditions for screening are to pass through an 80-mesh sieve.

[0036] S4. Add acid solution to the mixed powder and mix and stir, conduct activation in a water vapor atmosphere, and after cooling, obtain an activated product. Among them, the mass ratio of the mixed powder to the acid solution is 1:3.8, the acid solution is a phosphoric acid solution with a concentration of 10.5 mol / L; the conditions for activation are to heat at a heating rate of 7 °C / min, heat to 535 °C, and activate for 65 minutes.

[0037] S5. Take the activated product for cleaning and filtration, take the solid matter for drying to obtain activated carbon. Among them, the conditions for cleaning are to clean with deionized water until the pH value of the cleaning solution is neutral; the conditions for drying are to dry at a temperature of 108 °C for 5.8 hours.

[0038] Example 3

[0039] A preparation method of honeycomb-shaped solvent recovery activated carbon includes the following steps:

[0040] S1. Take bamboo, conduct ultrasonic cleaning, dry and sterilize it to obtain clean raw materials. Among them, the conditions for ultrasonic cleaning are to place the bamboo in distilled water and conduct ultrasonic cleaning for 45 minutes; the conditions for drying are to dry in an oven at 80 °C for 8 hours; the conditions for sterilization are to use ultraviolet irradiation for sterilization.

[0041] S2. Heat up the clean raw materials and then add the carbon body. Start the vacuum pump to control the pressure. After heat preservation and pressure maintenance treatment, cool to room temperature and then crush, and at the same time spray with an acidic solution. After solid-liquid separation, a mixed material is obtained. Among them, the mass ratio of the clean raw materials to the carbon body is 10:1.5. The carbon body is microporous activated carbon, where the micropore diameter of the microporous activated carbon is <2 nm and the micropore volume ratio is 80%. The condition for pressure control is to adjust the pressure to 0.05 pa. The acidic solution is a phosphoric acid solution with a concentration of 10 mol / L. The condition for heating and temperature rise is to heat to 95 °C. The time for heat preservation and pressure maintenance treatment is 30 min.

[0042] S3. Grind the mixed material into powder by ball milling, and screen the mixed material after ball milling to obtain a mixed powder. Among them, the condition for ball milling is to ball mill for 1 h at a rotation speed of 300 r / min. The condition for screening is to pass through an 80-mesh sieve.

[0043] S4. Add acid solution to the mixed powder and mix and stir. Activate in a water vapor atmosphere. After cooling, an activated product is obtained. Among them, the mass ratio of the mixed powder to the acid solution is 1:4.0. The acid solution is a phosphoric acid solution with a concentration of 11 mol / L. The condition for activation is to heat at a heating rate of 8 °C / min, heat to 550 °C, and activate for 60 min.

[0044] S5. Take the activated product for cleaning and filtration, and take the solid for drying to obtain activated carbon. Among them, the condition for cleaning is to clean with deionized water until the pH value of the cleaning solution is neutral. The condition for drying is to dry at a temperature of 110 °C for 5.5 h.

[0045] Example 4

[0046] Compared with Example 2, the difference is that the micropore volume ratio of the microporous activated carbon in step S² of Example 4 is 75%, and the other components, preparation steps, and parameters are the same.

[0047] Comparative Example 1

[0048] S2. Heat up the clean raw materials and then add the carbon body. Start the vacuum pump to control the pressure. After heat preservation and pressure maintenance treatment, cool to room temperature and then crush, and at the same time spray with an acidic solution. After solid-liquid separation, a mixed material is obtained. Among them, the mass ratio of the clean raw materials to the carbon body is 10:0.5. The carbon body is microporous activated carbon, where the micropore diameter of the microporous activated carbon is <2 nm and the micropore volume ratio is 78%. The condition for pressure control is to adjust the pressure to 0.03 pa. The acidic solution is a phosphoric acid solution with a concentration of 8.5 mol / L. The condition for heating and temperature rise is to heat to 92.5 °C. The time for heat preservation and pressure maintenance treatment is 38 min.

[0049] Compared with Example 2, the difference is that in Comparative Example 1, the mass ratio of the clean raw material to the carbon body in step S2 is 10:0.5, and the other components, preparation steps and parameters are the same.

[0050] Comparative Example 2

[0051] S2. After heating and raising the temperature of the clean raw material, add the carbon body, start the vacuum pump to control the pressure. After heat preservation and pressure maintenance treatment, cool to room temperature and then crush, and at the same time spray with an acidic solution. After solid-liquid separation, a mixed material is obtained; wherein, the mass ratio of the clean raw material to the carbon body is 10:1.2, the carbon body is microporous activated carbon, wherein the micropore diameter of the microporous activated carbon is <2 nm, the mesopore diameter is 2 - 50 nm, the micropore volume ratio is 30%, and the mesopore volume ratio is 48%; the condition for controlling the pressure is to adjust the pressure to 0.03 pa; the acidic solution is a phosphoric acid solution with a concentration of 8.5 mol / L; the condition for heating and raising the temperature is to heat to 92.5 °C; the time for heat preservation and pressure maintenance treatment is 38 min;

[0052] Compared with Example 2, the difference is that in Comparative Example 2, the micropore diameter of the microporous activated carbon in step S2 is <2 nm, the mesopore diameter is 2 - 50 nm, the micropore volume ratio is 30%, and the mesopore volume ratio is 48%, and the other components, preparation steps and parameters are the same.

[0053] Comparative Example 3

[0054] S2. After heating and raising the temperature of the clean raw material, add the carbon body, start the vacuum pump to control the pressure. After heat preservation and pressure maintenance treatment, cool to room temperature and then crush to obtain a mixed material; wherein, the mass ratio of the clean raw material to the carbon body is 10:1.2, the carbon body is microporous activated carbon, wherein the micropore diameter of the microporous activated carbon is <2 nm, and the micropore volume ratio is 78%; the condition for controlling the pressure is to adjust the pressure to 0.03 pa; the condition for heating and raising the temperature is to heat to 92.5 °C; the time for heat preservation and pressure maintenance treatment is 38 min;

[0055] Compared with Example 2, the difference is that in Comparative Example 3, no phosphoric acid solution is used for spraying, and the other components, preparation steps and parameters are the same.

[0056] Comparative Example 4

[0057] Compared with Example 2, the difference is that in step S2 of Comparative Example 4, a phosphoric acid solution with a concentration of 5 mol / L is used for spraying, and the other components, preparation steps and parameters are the same.

[0058] Comparative Example 5

[0059] Compared with Example 2, the difference lies in that in step S2 of Comparative Example 5, a phosphoric acid solution with a concentration of 12 mol / L was used for spraying, and the other components, preparation steps, and parameters were the same.

[0060] Comparative Example 6

[0061] Compared with Example 2, the difference lies in that in Comparative Example 6, the mass ratio of the mixed powder to the acid solution in step S4 is 1:5, and the other components, preparation steps, and parameters are the same.

[0062] Comparative Example 7

[0063] Compared with Example 2, the difference lies in that in Comparative Example 7, the acid solution in step S4 is a phosphoric acid solution with a concentration of 13 mol / L, and the other components, preparation steps, and parameters are the same.

[0064] Comparative Example 8

[0065] Compared with Example 2, the difference lies in that in Comparative Example 8, a nitrogen atmosphere was used for activation instead of a steam atmosphere in step S4, and the other components, preparation steps, and parameters were the same.

[0066] Adsorption performance test

[0067] Weigh 0.02 g of the activated carbon prepared in Examples 1-4 and Comparative Examples 1-8 respectively, add them to 200 mL of methylene blue, acid red 18, and congo red test solutions with a concentration of 200 mg / L, and measure the concentration of organic matter in the test solution after 2 hours of adsorption, and then calculate the adsorption capacity. The test results are shown in Table 1.

[0068] Table 1

[0069]

[0070] It can be seen from the test results in Table 1 that compared with the activated carbon prepared in Comparative Examples 1-8, the activated carbon prepared in Examples 1-4 of the present invention has significantly better adsorption effects on methylene blue, acid red 18, and congo red than Comparative Examples 1-8.

[0071] Comparative analysis of Examples 1-4 and Comparative Examples 1-2 shows that the addition of too little microporous activated carbon reduces the crushing effect and is not conducive to later activation. The microporous activated carbon has more mesopores, which may lead to over-activation and collapse in the later stage.

[0072] Comparative analysis of Examples 1-4 and Comparative Examples 3-7 shows that spraying an appropriate amount of phosphoric acid solution for auxiliary crushing and using a small amount of intermittent spraying method can greatly improve the crushing efficiency. At the same time, using phosphoric acid solution can also pre-activate the bamboo raw materials, which is conducive to the later phosphoric acid activation and can avoid over-activation.

[0073] Comparative analysis of Examples 1-4 and Comparative Example 8 shows that the use of a water vapor atmosphere is beneficial to the formation of mesopores during the phosphoric acid activation process.

[0074] The above are only the preferred embodiments of the present invention, and do not impose any formal limitations on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications within the scope of the technical solution of the present invention to obtain equivalent embodiments with equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of honeycomb solvent recovery activated carbon, characterized in that The preparation method includes the following steps: S1. Take bamboo, perform ultrasonic cleaning, dry and sterilize it to obtain clean raw materials; S2. After heating and raising the temperature of the clean raw materials, add carbon bodies, start a vacuum pump to control the pressure, perform heat preservation and pressure maintenance treatment, cool to room temperature and then pulverize, and at the same time spray with an acidic solution. After solid-liquid separation, obtain a mixed material; S3. Grind the mixed material into powder, screen the mixed material after ball milling to obtain mixed powder; S4. Add acid solution to the mixed powder and mix and stir, activate it under a water vapor atmosphere, and after cooling, obtain an activated product; S5. Take the activated product for cleaning and filtering, take the solid for drying to obtain activated carbon; In step S2, the mass ratio of the clean raw materials to the carbon bodies is 10:1 - 1.5, the acidic solution is a phosphoric acid solution with a concentration of 7 - 10 mol / L, the carbon bodies are microporous activated carbons, the micropore diameter of the microporous activated carbon is <2 nm, and the micropore volume ratio is 75 - 80%; the condition for pressure control is to adjust the pressure to 0.01 - 0.05 pa; In step S4, the mass ratio of the mixed powder to the acid solution is 1:3.5 - 4.0, and the acid solution is a phosphoric acid solution with a concentration of 10 - 11 mol / L.

2. The preparation method of a honeycomb solvent recovery activated carbon according to claim 1, characterized in that: In step S1, the condition for ultrasonic cleaning is to place the bamboo in distilled water and perform ultrasonic cleaning for 30 - 45 min; the condition for drying is to dry it in an oven at 75 - 80 °C for 8 - 10 h; the condition for sterilization is to sterilize it by ultraviolet irradiation.

3. The preparation method of a honeycomb solvent recovery activated carbon according to claim 1, characterized in that: In step S2, the condition for heating and raising the temperature is to heat to 90 - 95 °C; the time for heat preservation and pressure maintenance treatment is 30 - 45 min.

4. The preparation method of a honeycomb solvent recovery activated carbon according to claim 1, characterized in that: In step S3, the condition for ball milling is to ball mill at a rotation speed of 200 - 300 r / min for a ball milling time of 1 - 1.5 h; the condition for screening is to pass through an 80 - mesh sieve.

5. The preparation method of a honeycomb solvent recovery activated carbon according to claim 1, characterized in that: In step S4, the condition for activation is to activate at a heating rate of 6 - 8 °C / min, heat to 520 - 550 °C, and activate for 60 - 70 min.

6. The preparation method of a honeycomb solvent recovery activated carbon according to claim 1, characterized in that: In step S5, the condition for cleaning is to clean with deionized water until the pH value of the cleaning solution is neutral; the condition for drying is to dry at a temperature of 105 - 110 °C for 5.5 - 6.0 h.

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