Modified activated carbon for removing n-butane and method for preparing the same

Abstract

The present application relates to the technical field of adsorption material preparation, and particularly relates to a modified activated carbon for removing n-butane and a preparation method thereof, comprising the following steps: S1, impregnating and activating coconut shell carbon to obtain activated carbon after activation; S2, reacting the activated carbon after activation with polyethyleneimine and epichlorohydrin to obtain activated carbon loaded with polyethyleneimine; S3, dispersing the activated carbon loaded with polyethyleneimine in DMF, adding EDC, NHS and 2,5-bis(trifluoromethyl) terephthalic acid, and reacting to obtain functionalized activated carbon; S4, reacting modified molecular sieve of sucrose with aminosilane coupling agent to obtain composite modified molecular sieve; and S5, reacting the composite modified molecular sieve, the functionalized activated carbon and glutaraldehyde to obtain modified activated carbon. The functionalized activated carbon and the composite modified molecular sieve are covalently connected by a chemical crosslinking agent, multiple adsorption sites are formed, and the adsorption capacity of the modified activated carbon for n-butane is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of adsorption material preparation technology, and in particular to a modified activated carbon for removing n-butane and its preparation method. Background Technology

[0002] n-Butane is an important chemical raw material, a flammable and explosive gas, posing certain dangers during storage and transportation. In industrial production, if n-butane leaks and accumulates in the air, it can cause a violent explosion upon contact with an ignition source. In daily life, n-butane is one of the heavier-than-air pollutants in automobile exhaust, traveling long distances and widely distributed in ambient air. When mixed with air, n-butane forms an explosive mixture. Under fire and high-temperature conditions, n-butane can produce a flammable explosion; inhalation may cause dizziness, nausea, and adverse health effects in humans. For the treatment of organic waste gases such as n-butane, researchers have developed various control technologies, including adsorption, condensation, absorption, as well as biochemical and membrane separation methods. Among these, adsorption is considered one of the most effective removal methods due to its high efficiency. Compared with other treatment methods, adsorption technology has advantages such as high removal rate, thorough purification, low energy consumption, mature technology, and the ability to recover and reuse solvents, and it is relatively simple to operate.

[0003] Activated carbon stands out among many adsorption materials due to its large specific surface area, high adsorption capacity, excellent treatment efficiency, low cost, and abundant resource reserves, making it an ideal choice for widespread application in such scenarios. Activated carbon not only excels in mitigating environmental pollution but also effectively controls long-term operating costs through its recyclable nature, achieving a win-win situation for both economic and ecological benefits. However, traditional activated carbon suffers from low adsorption capacity when treating oil and gas. This challenge has prompted researchers to continuously explore activated carbon modification technologies to enhance its adsorption efficiency and make it more adaptable to diverse application needs.

[0004] Existing patent CN202111112607.5 discloses a type of wood-based activated carbon for automotive carbon canisters and its preparation technology. The activated carbon preparation method disclosed in this invention is as follows: 1. Peach shell powder and other wood powders are mixed and sieved at a certain mass ratio, then phosphate is added for curing, followed by the addition of 5-20 wt% of a pore-expanding agent such as zinc chloride for kneading. 2. The product is blended with 1%-10 wt% of a binder such as sodium carboxymethyl cellulose and extruded at high temperature. 3. The formed product is hardened at 180-250℃ for 12-36 hours, and then activated at 450-700℃ for 1-4 hours under a protective atmosphere. 4. After washing, drying, and sieving the activated product, activated carbon granules are obtained. The activated carbon granules obtained by this invention have high n-butane adsorption capacity and wear resistance, meeting the application requirements of next-generation automotive carbon canister activated carbon. However, the above technical solutions mainly optimize the internal pores of activated carbon by using specific pore-expanding agents to match the adsorption and desorption characteristics of n-butane. They mainly rely on physical adsorption and have disadvantages such as low adsorption selectivity and unstable adsorption performance, resulting in low adsorption efficiency for n-butane. Summary of the Invention

[0005] In view of this, the present invention proposes a method for preparing modified activated carbon for removing n-butane, so as to solve the problem of low adsorption efficiency of activated carbon for n-butane in the prior art.

[0006] The technical solution of this invention is achieved as follows: This invention provides a method for preparing modified activated carbon for removing n-butane, comprising the following steps:

[0007] S1. The coconut shell charcoal is impregnated in an impregnation solution and then activated to obtain activated charcoal.

[0008] S2. Disperse the activated carbon in deionized water, then add polyethyleneimine and epichlorohydrin to it, and stir the reaction at 60-70℃ for 4-6 hours to obtain activated carbon loaded with polyethyleneimine.

[0009] S3. Disperse the activated carbon loaded with polyethyleneimine in DMF, add EDC and NHS, then add 2,5-bis(trifluoromethyl)terephthalic acid, stir the reaction at room temperature for 8-10 h to obtain functionalized activated carbon.

[0010] S4. Disperse the sucrose-modified molecular sieve in DMF, then add an aminosilane coupling agent, and stir at 70-80℃ for 3-6 hours to obtain a composite modified molecular sieve.

[0011] S5. Disperse the composite modified molecular sieve and functionalized activated carbon in water, add sodium bicarbonate solution to adjust the pH to 7.5-9, add glutaraldehyde, and stir the reaction at 40-50℃ for 8-12 hours. After the reaction is completed, filter, wash and dry to obtain modified activated carbon.

[0012] In this invention, activated carbon is functionalized by introducing 2,5-bis(trifluoromethyl)terephthalic acid, and molecular sieves are modified with sucrose and aminated. Glutaraldehyde is then used to covalently link the functionalized activated carbon with the composite modified molecular sieve, forming a structurally stable composite material. The modified activated carbon prepared through this technical solution not only possesses an excellent pore structure but also combines CH...F hydrogen bonding with the selective adsorption of molecular sieves, enabling efficient and selective removal of n-butane, thereby achieving highly efficient adsorption of n-butane.

[0013] Based on the above technical solutions, preferably, step S1 specifically includes:

[0014] S11. Crush and sieve the coconut shell charcoal to obtain granular charcoal with a mesh size of 30-60 mesh;

[0015] S12. Disperse the granular carbon in the impregnation solution for impregnation treatment. The impregnation treatment temperature is 30-80℃ and the impregnation treatment time is 2-15h.

[0016] S13. The impregnated granular carbon is heated to 650-750℃ at a rate of 2.3-2.7℃ / min under a nitrogen atmosphere and the activation reaction is carried out for 1.5-2.5h to obtain activated carbon.

[0017] Based on the above technical solutions, preferably, in step S12, the mass ratio of granular carbon to impregnation solution is 1:2.8-3.2, the concentration of impregnation solution is 5%-15%, and the impregnation solution is any one of potassium hydroxide solution, sodium hydroxide solution, ammonium chloride solution, and acetic acid solution.

[0018] In step S11, crushing and screening the coconut shell charcoal can improve the uniformity of the raw materials; in step S12, the impregnation solution can effectively etch the surface of the coconut shell charcoal to form more pore structures; in step S13, the activation treatment further improves the specific surface area and porosity of the activated carbon.

[0019] Based on the above technical solutions, preferably, in step S2, the mass ratio of activated carbon, polyethyleneimine and epichlorohydrin is 6-9:4-6:2-4.

[0020] Based on the above technical solutions, preferably, in step S3, the mass ratio of activated carbon loaded with polyethyleneimine, 2,5-bis(trifluoromethyl)terephthalic acid, EDC and NHS is 10-15:1-2:0.5-0.8:0.5-0.8.

[0021] The initial functionalization modification of activated carbon is achieved by the ring-opening reaction between the amino groups on the polyethyleneimine molecular chain and the epoxy groups of epichlorohydrin to form stable chemical bonds, thereby fixing the polyethyleneimine molecules on the surface of activated carbon. Then, the amino groups remaining on the activated carbon loaded with polyethyleneimine undergo an amidation reaction with the carboxyl groups of 2,5-bis(trifluoromethyl)terephthalic acid, thereby introducing a benzene ring structure containing trifluoromethyl groups onto the surface of the activated carbon.

[0022] Based on the above technical solutions, the preferred method for preparing sucrose-modified molecular sieves in step S4 is as follows: sucrose is dissolved in water to prepare a sucrose-modified solution, molecular sieves are added, the mixture is placed in an ultrasonic cleaner and sonicated for 2 hours, and then calcined under a nitrogen atmosphere to obtain sucrose-modified molecular sieves.

[0023] Based on the above technical solutions, preferably, the amount of sucrose added is 0.8-1.2 times the mass of the molecular sieve, and the molecular sieve is MCM-48.

[0024] Based on the above technical solutions, preferably, in step S4, the mass ratio of sucrose-modified molecular sieve to aminosilane coupling agent is 5-8:1, and the aminosilane coupling agent is 3-aminopropyltriethoxysilane or 3-aminopropyltrimethoxysilane.

[0025] During calcination under a nitrogen atmosphere, sucrose undergoes pyrolysis and carbonization, forming a uniform carbon layer on the surface and in the channels of the molecular sieve, thereby increasing the nonpolarity of the molecular sieve surface. Then, the alkoxy groups in the silane coupling agent undergo a condensation reaction with the hydroxyl groups on the surface of the molecular sieve to introduce amino functional groups into the surface of the molecular sieve, providing active sites for subsequent reactions.

[0026] Based on the above technical solutions, preferably, in step S5, the mass ratio of the composite modified molecular sieve to the functionalized activated carbon is 1:1-1.5, and the amount of glutaraldehyde added is 5-15% of the mass of the functionalized activated carbon.

[0027] Functionalized activated carbon and sucrose-modified molecular sieves are chemically compounded using glutaraldehyde crosslinking agent to form a composite material with synergistic adsorption effect. The two components are firmly linked by covalent bonds, ensuring the structural stability of the composite material during use. At the same time, the flexible characteristics of the glutaraldehyde molecular chain provide a certain structural buffer space for the composite material, which is conducive to maintaining the structural integrity of the material during adsorption-desorption.

[0028] The present invention also provides a modified activated carbon for removing n-butane prepared by the preparation method described in any of the preceding claims.

[0029] The modified activated carbon for removing n-butane and its preparation method of the present invention have the following advantages over the prior art:

[0030] Beneficial effects:

[0031] (1) The modified activated carbon formed by covalently linking functionalized activated carbon and composite modified molecular sieve with a chemical crosslinking agent creates multiple adsorption sites, which have a good effect on the adsorption of n-butane and can significantly improve the adsorption capacity of n-butane. Among them, the selective adsorption sites provided by the functionalized activated carbon and the high specific surface area and optimized pore structure provided by the composite modified molecular sieve complement each other, successfully realizing the synergistic effect of physical adsorption and chemical adsorption, thereby significantly improving the adsorption capacity and selectivity of the material for n-butane;

[0032] (2) This invention significantly improves the adsorption selectivity of activated carbon for n-butane by introducing trifluoromethylbenzene ring groups on the surface of activated carbon through functional modification. Specifically, the trifluoromethyl groups containing CF bonds significantly enhance the specificity of adsorption by forming stable CH...F hydrogen bonds with n-butane molecules. In addition, the chemical modification process on the surface of activated carbon maintains the good pore structure of the raw materials and endows it with excellent surface properties, thus making up for the shortcomings of traditional activated carbon, which mainly relies on physical pore adsorption, and achieving improved selectivity.

[0033] (3) This invention prepares a composite modified molecular sieve by modifying the molecular sieve with sucrose and further reacting it with a silane coupling agent, which significantly improves the adsorption performance and chemical reactivity of the molecular sieve. Sucrose modification forms a uniform carbon layer on the surface of the molecular sieve through a carbonization process, which optimizes the pore size distribution of the molecular sieve, enhances the hydrophobicity of the material, and facilitates the adsorption of n-butane; at the same time, the amino functional groups introduced by the silane coupling agent can further improve the adsorption capacity through hydrogen bonding or electrostatic interaction, and provide active sites for surface functionalization and chemical cross-linking with activated carbon during the reaction process. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a flowchart of the preparation method of the modified activated carbon for removing n-butane according to the present invention. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] It should be noted that the MCM-48 molecular sieve was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and its particle size is 2.6 nm.

[0038] Example 1

[0039] like Figure 1 As shown, this embodiment provides a method for preparing modified activated carbon for removing n-butane, including the following steps:

[0040] S1. 10g of coconut shell charcoal is crushed and sieved to obtain 45-mesh granular charcoal. The granular charcoal is washed with deionized water and dried for later use. Then, 30g of potassium hydroxide is dissolved in deionized water to prepare a 10% potassium hydroxide solution. 10g of dried granular charcoal is dispersed in the potassium hydroxide solution and impregnated at 55℃ for 8.5h. After impregnation, it is dried in an oven at 110℃. Under nitrogen protection, the atmosphere protection furnace is heated to 700℃ at a heating rate of 2.5℃ to activate the impregnated granular charcoal for 2h. After the reaction is completed, it is cooled to room temperature to obtain activated carbon.

[0041] S2. Disperse 16g of activated carbon in 160ml of deionized water, then add 10g of polyethyleneimine and 6g of epichlorohydrin, stir and react at 65℃ for 5h. After the reaction is completed, filter, wash and dry to obtain activated carbon loaded with polyethyleneimine.

[0042] S3. Take 12.5g of activated carbon loaded with polyethyleneimine and disperse it in 125ml of DMF. Add 0.65g of EDC and 0.65g of NHS, then add 1.5g of 2,5-bis(trifluoromethyl)terephthalic acid. Stir the reaction at room temperature for 9h. After the reaction is completed, filter, wash and dry to obtain functionalized activated carbon.

[0043] S4. Dissolve 10g of sucrose in water to prepare a sucrose-modified solution, add 10g of MCM-48 molecular sieve, put the mixture into an ultrasonic cleaner and sonicate for 2 hours, wash and dry, and then calcine at 550℃ for 4.5 hours under a nitrogen atmosphere to obtain sucrose-modified molecular sieve.

[0044] 6.5g of sucrose-modified molecular sieve was dispersed in DMF, and then 1g of 3-aminopropyltriethoxysilane was added. The mixture was stirred at 75℃ for 4.5h. After the reaction was completed, the mixture was filtered, washed and dried to obtain the composite modified molecular sieve.

[0045] S5. Disperse 1g of composite modified molecular sieve and 1.25g of functionalized activated carbon in 200ml of water, add sodium bicarbonate solution (mass percentage of 1-2%) to adjust the pH to 7.5-9, add 0.12g of glutaraldehyde, stir and react at 45℃ for 10h. After the reaction is completed, filter, wash and dry to obtain modified activated carbon.

[0046] Example 2

[0047] This embodiment provides a method for preparing modified activated carbon for removing n-butane, comprising the following steps:

[0048] S1. 10g of coconut shell charcoal is crushed and sieved to obtain granular charcoal with a mesh size of 30. The granular charcoal is washed with deionized water and dried for later use. Then, 28g of sodium hydroxide is dissolved in deionized water to prepare a 5% sodium hydroxide solution. 10g of dried granular charcoal is dispersed in the sodium hydroxide solution and impregnated at 30℃ for 15h. After impregnation, it is dried in an oven at 110℃. Under nitrogen protection, the atmosphere protection furnace is heated to 650℃ at a heating rate of 2.3℃. The impregnated granular charcoal is activated for 2.5h. After the reaction is completed, it is cooled to room temperature to obtain activated carbon.

[0049] S2. Disperse 12g of activated carbon in 200ml of deionized water, then add 8g of polyethyleneimine and 4g of epichlorohydrin to it, stir and react at 60℃ for 6h. After the reaction is completed, filter, wash and dry to obtain activated carbon loaded with polyethyleneimine.

[0050] S3. Take 10g of activated carbon loaded with polyethyleneimine and disperse it in 100ml of DMF. Add 0.5g of EDC and 0.5g of NHS, then add 1g of 2,5-bis(trifluoromethyl)terephthalic acid. Stir the reaction at room temperature for 10h. After the reaction is completed, filter, wash and dry to obtain functionalized activated carbon.

[0051] S4. Dissolve 8g of sucrose in water to prepare a sucrose-modified solution, add 10g of MCM-48 molecular sieve, put the mixture into an ultrasonic cleaner and sonicate for 2 hours, wash and dry, and then calcine at 450℃ for 6 hours under a nitrogen atmosphere to obtain sucrose-modified molecular sieve.

[0052] 5g of sucrose-modified molecular sieve was dispersed in DMF, and then 1g of 3-aminopropyltriethoxysilane was added. The mixture was stirred at 70℃ for 6 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the composite modified molecular sieve.

[0053] S5. Disperse 1g of composite modified molecular sieve and 1g of functionalized activated carbon in 200ml of water, add sodium bicarbonate solution (mass percentage of 1-2%) to adjust the pH to 7.5-9, add 0.05g of glutaraldehyde, stir and react at 40℃ for 12h. After the reaction is completed, filter, wash and dry to obtain modified activated carbon.

[0054] Example 3

[0055] This embodiment provides a method for preparing modified activated carbon for removing n-butane, comprising the following steps:

[0056] S1. 10g of coconut shell charcoal is crushed and sieved to obtain 60-mesh granular charcoal. The granular charcoal is washed with deionized water and dried for later use. Then, 32g of acetic acid is dissolved in deionized water to prepare a 15% acetic acid solution. 10g of dried granular charcoal is dispersed in the acetic acid solution and impregnated at 80℃ for 2h. After impregnation, it is dried in an oven at 110℃. Under nitrogen protection, the atmosphere protection furnace is heated to 750℃ at a heating rate of 2.7℃. The impregnated granular charcoal is activated for 1.5h. After the reaction is completed, it is cooled to room temperature to obtain activated carbon.

[0057] S2. Disperse 18g of activated carbon in 200ml of deionized water, then add 12g of polyethyleneimine and 8g of epichlorohydrin to it, stir and react at 70℃ for 4h. After the reaction is completed, filter, wash and dry to obtain activated carbon loaded with polyethyleneimine.

[0058] S3. Take 15g of activated carbon loaded with polyethyleneimine and disperse it in 100ml of DMF. Add 0.8g of EDC and 0.8g of NHS, then add 2g of 2,5-bis(trifluoromethyl)terephthalic acid. Stir the reaction at room temperature for 8h. After the reaction is completed, filter, wash and dry to obtain functionalized activated carbon.

[0059] S4. Dissolve 12g of sucrose in water to prepare a sucrose-modified solution, add 10g of MCM-48 molecular sieve, put the mixture into an ultrasonic cleaner and sonicate for 2 hours, wash and dry, and then calcine at 650℃ for 3 hours under a nitrogen atmosphere to obtain sucrose-modified molecular sieve.

[0060] 8g of sucrose-modified molecular sieve was dispersed in DMF, and then 1g of 3-aminopropyltriethoxysilane was added. The mixture was stirred at 80℃ for 3h. After the reaction was completed, the mixture was filtered, washed and dried to obtain the composite modified molecular sieve.

[0061] S5. Disperse 1g of composite modified molecular sieve and 1.5g of functionalized activated carbon in 200ml of water, add sodium bicarbonate solution (mass percentage of 1-2%) to adjust the pH to 7.5-9, add 0.22g of glutaraldehyde, stir and react at 50℃ for 8h. After the reaction is completed, filter, wash and dry to obtain modified activated carbon.

[0062] Comparative Example 1

[0063] This comparative example provides a method for preparing modified activated carbon for removing n-butane, comprising the following steps:

[0064] S1. 10g of coconut shell charcoal is crushed and sieved to obtain 45-mesh granular charcoal. The granular charcoal is washed with deionized water and dried for later use. Then, 30g of potassium hydroxide is dissolved in deionized water to prepare a 10% potassium hydroxide solution. 10g of dried granular charcoal is dispersed in the potassium hydroxide solution and impregnated at 55℃ for 8.5h. After impregnation, it is dried in an oven at 110℃. Under nitrogen protection, the atmosphere protection furnace is heated to 700℃ at a heating rate of 2.5℃ to activate the impregnated granular charcoal for 2h. After the reaction is completed, it is cooled to room temperature to obtain activated carbon.

[0065] S2. Dissolve 10g of sucrose in water to prepare a sucrose-modified solution, add 10g of MCM-48 molecular sieve, put the mixture into an ultrasonic cleaner and sonicate for 2 hours, wash and dry, and then calcine at 550℃ for 4.5 hours under a nitrogen atmosphere to obtain sucrose-modified molecular sieve.

[0066] S3. Disperse 1g of sucrose-modified molecular sieve and 1.25g of activated carbon in 200ml of water, add sodium bicarbonate solution (mass percentage 1-2%) to adjust the pH to 7.5-9, add 0.12g of glutaraldehyde, stir and react at 45℃ for 10h. After the reaction is completed, filter, wash and dry to obtain modified activated carbon.

[0067] Comparative Example 2

[0068] This comparative example provides a method for preparing modified activated carbon for removing n-butane, comprising the following steps:

[0069] S1-S2 are the same as in Example 1;

[0070] S3. Dissolve 10g of sucrose in water to prepare a sucrose-modified solution, add 10g of MCM-48 molecular sieve, put the mixture into an ultrasonic cleaner and sonicate for 2 hours, wash and dry, and then calcine at 550℃ for 4.5 hours under a nitrogen atmosphere to obtain sucrose-modified molecular sieve.

[0071] 6.5g of sucrose-modified molecular sieve was dispersed in DMF, and then 1g of 3-aminopropyltriethoxysilane was added. The mixture was stirred at 75℃ for 4.5h. After the reaction was completed, the mixture was filtered, washed and dried to obtain the composite modified molecular sieve.

[0072] S4. Disperse 1g of composite modified molecular sieve and 1.25g of activated carbon loaded with polyethyleneimine in 200ml of water, add sodium bicarbonate solution (mass percentage of 1-2%) to adjust the pH to 7.5-9, add 0.12g of glutaraldehyde, stir and react at 45℃ for 10h. After the reaction is completed, filter, wash and dry to obtain modified activated carbon.

[0073] Comparative Example 3

[0074] This comparative example provides a method for preparing modified activated carbon for removing n-butane, comprising the following steps:

[0075] S1-S3 are the same as in Example 1;

[0076] S4. Dissolve 10g of sucrose in water to prepare a sucrose-modified solution, add 10g of MCM-48 molecular sieve, put the mixture into an ultrasonic cleaner and sonicate for 2 hours, wash and dry, and then calcine at 550℃ for 4.5 hours under a nitrogen atmosphere to obtain sucrose-modified molecular sieve.

[0077] S5. Disperse 1g of sucrose-modified molecular sieve and 1.25g of functionalized activated carbon in 200ml of water, add sodium bicarbonate solution (mass percentage of 1-2%) to adjust the pH to 7.5-9, add 0.12g of glutaraldehyde, stir and mix at 45℃ for 10h. After mixing, filter, wash and dry to obtain modified activated carbon.

[0078] Comparative Example 4

[0079] This comparative example provides a method for preparing modified activated carbon for removing n-butane, comprising the following steps:

[0080] S1-S4 are the same as in Example 1;

[0081] S5. Disperse 1g of composite modified molecular sieve and 1.25g of functionalized activated carbon in 200ml of water, add sodium bicarbonate solution (mass percentage of 1-2%) to adjust the pH to 7.5-9, stir and mix at room temperature for 10h, after mixing, filter, wash and dry to obtain modified activated carbon.

[0082] Performance testing

[0083] The modified activated carbon prepared in the examples and comparative examples was tested according to the national standard GB / T 20449-2006 "Test Method for Butane Working Capacity of Activated Carbon". The test conditions are as follows:

[0084] Carbon layer height: (10±0.2)cm.

[0085] n-Butane flow rate: (250±5) mL / min.

[0086] Nitrogen or air flow rate: (300±5) mL / min.

[0087] Adsorption and desorption temperatures: (25±0.5)℃

[0088] Result calculation:

[0089] Butane working capacity (BWC)

[0090]

[0091] In the formula:

[0092] BWC V : Working volume capacity of activated carbon butane, in grams per 100 milliliters (g / 100ml);

[0093] ρ: Apparent density or packing density of activated carbon sample, in grams per milliliter (g / ml);

[0094] m1: The mass of the sample tube and stopper, in grams (g);

[0095] m2: The mass of carbon and stopper added to the sample tube before adsorption, in grams (g);

[0096] m3: The mass of carbon, n-butane, and stopper added to the sample tube after saturated adsorption, in grams (g);

[0097] m4: The mass of carbon added to the sample tube after desorption, the undesorbed n-butane, and the stopper, in grams (g).

[0098] The test results are shown in Table 1.

[0099] Table 1 n-Butane Adsorption Capacity

[0100] Adsorption capacity (g / 100ml) Example 1 23.20 Example 2 21.68 Example 3 22.96 Comparative Example 1 10.52 Comparative Example 2 13.08 Comparative Example 3 14.16 Comparative Example 4 15.44

[0101] As shown in Table 1, the modified activated carbon prepared by the technical solution of the present invention has a better n-butane adsorption effect, and can greatly improve the working volume capacity of activated carbon for n-butane compared with the technical solution of the comparative example.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing modified activated carbon for removing n-butane, characterized in that: Includes the following steps: S1. The coconut shell charcoal is impregnated in an impregnation solution and then activated to obtain activated charcoal. S2. Disperse the activated carbon in deionized water, then add polyethyleneimine and epichlorohydrin to it, and stir the reaction at 60-70℃ for 4-6 hours to obtain activated carbon loaded with polyethyleneimine. S3. Disperse the activated carbon loaded with polyethyleneimine in DMF, add EDC and NHS, then add 2,5-bis(trifluoromethyl)terephthalic acid, stir the reaction at room temperature for 8-10 h to obtain functionalized activated carbon. S4. Disperse the sucrose-modified molecular sieve in DMF, then add an aminosilane coupling agent, and stir at 70-80℃ for 3-6 hours to obtain a composite modified molecular sieve. S5. Disperse the composite modified molecular sieve and functionalized activated carbon in water, add sodium bicarbonate solution to adjust the pH to 7.5-9, add glutaraldehyde, and stir the reaction at 40-50℃ for 8-12 hours. After the reaction is completed, filter, wash and dry to obtain modified activated carbon.

2. The method for preparing modified activated carbon for removing n-butane as described in claim 1, characterized in that: Step S1 specifically includes: S11. Crush and sieve the coconut shell charcoal to obtain granular charcoal with a mesh size of 30-60 mesh; S12. Disperse the granular carbon in the impregnation solution for impregnation treatment. The impregnation treatment temperature is 30-80℃ and the impregnation treatment time is 2-15h. S13. The impregnated granular carbon is heated to 650-750℃ at a rate of 2.3-2.7℃ / min under a nitrogen atmosphere and the activation reaction is carried out for 1.5-2.5h to obtain activated carbon.

3. The method for preparing modified activated carbon for removing n-butane as described in claim 2, characterized in that: In step S12, the mass ratio of granular carbon to impregnation solution is 1:2.8-3.2, the concentration of impregnation solution is 5%-15%, and the impregnation solution is any one of potassium hydroxide solution, sodium hydroxide solution, ammonium chloride solution, and acetic acid solution.

4. The method for preparing modified activated carbon for removing n-butane as described in claim 1, characterized in that: In step S2, the mass ratio of activated carbon, polyethyleneimine, and epichlorohydrin is 6-9:4-6:2-4.

5. The method for preparing modified activated carbon for removing n-butane as described in claim 1, characterized in that: In step S3, the mass ratio of activated carbon loaded with polyethyleneimine, 2,5-bis(trifluoromethyl)terephthalic acid, EDC and NHS is 10-15:1-2:0.5-0.8:0.5-0.

8.

6. The method for preparing modified activated carbon for removing n-butane as described in claim 1, characterized in that: In step S4, the preparation method of sucrose modified molecular sieve is as follows: sucrose is dissolved in water to prepare a sucrose modified solution, molecular sieve is added, the mixture is placed in an ultrasonic cleaner and ultrasonicated for 2 hours, and then calcined under a nitrogen atmosphere to obtain sucrose modified molecular sieve.

7. The method for preparing modified activated carbon for removing n-butane as described in claim 6, characterized in that: The amount of sucrose added is 0.8-1.2 times the mass of the molecular sieve, and the molecular sieve is MCM-48.

8. The method for preparing modified activated carbon for removing n-butane as described in claim 1, characterized in that: In step S4, the mass ratio of sucrose-modified molecular sieve to aminosilane coupling agent is 5-8:1, and the aminosilane coupling agent is 3-aminopropyltriethoxysilane or 3-aminopropyltrimethoxysilane.

9. The method for preparing modified activated carbon for removing n-butane as described in claim 1, characterized in that: In step S5, the mass ratio of the composite modified molecular sieve to the functionalized activated carbon is 1:1-1.5, and the amount of glutaraldehyde added is 5-15% of the mass of the functionalized activated carbon.

10. A modified activated carbon for removing n-butane prepared by the preparation method according to any one of claims 1-9.

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