Modified activated carbon for removing n-butane and preparation method thereof

Abstract

The invention relates to the technical field of adsorption material preparation, in particular to modified activated carbon for removing n-butane and a preparation method thereof.The preparation method comprises the following steps that S1, coconut shell charcoal is impregnated and activated, and activated activated carbon is obtained; s2, enabling the activated active carbon to react with polyethyleneimine and epoxy chloropropane to obtain polyethyleneimine-loaded active carbon; s3, dispersing the active carbon loaded with polyethyleneimine in DMF, adding EDC, NHS and 2, 5-bis (trifluoromethyl) terephthalic acid, and reacting to obtain functionalized active carbon; s4, reacting the sucrose modified molecular sieve with an aminated silane coupling agent to obtain a composite modified molecular sieve; s5, reacting the composite modified molecular sieve, the functionalized activated carbon and glutaraldehyde to obtain the modified activated carbon. The functionalized activated carbon and the composite modified molecular sieve are covalently linked through the chemical cross-linking agent to form multiple adsorption sites, so that the adsorption capacity of the modified activated carbon to n-butane is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of adsorption materials, and particularly to a modified activated carbon for removing n-butane and a preparation method thereof. Background Art

[0002] n-Butane is an important chemical raw material and a flammable and explosive gas, and there are also certain risks during storage and transportation. In industrial production, if n-butane leaks and accumulates in the air, a violent explosion may occur when encountering a fire source. In daily life, n-butane is one of the pollutants heavier than air in vehicle exhaust, with a long propagation distance and wide distribution in ambient air. When mixed with air, n-butane forms an explosive mixture. In the case of fire and high temperature, n-butane will produce a combustible explosion, and human inhalation may cause dizziness, nausea and adverse health manifestations. For the treatment of organic waste gases such as n-butane, researchers have developed a variety of control technologies, including adsorption, condensation, absorption, as well as biochemical and membrane separation methods. Among them, the adsorption method is considered to be one of the most effective removal means due to its high efficiency. Compared with other treatment methods, the adsorption technology has the advantages of high removal rate, thorough purification, low energy consumption, mature process, etc., and can realize the recycling of solvents, and is also 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 rich resource reserves, and becomes an ideal choice widely used in such scenarios. Activated carbon not only performs excellently in reducing environmental pollution, but also effectively controls the long-term operation cost through its renewable and recyclable characteristics, achieving a win-win situation of economic and ecological benefits. However, traditional activated carbon has the characteristic of small adsorption capacity when treating oil and gas adsorption, and this challenge has prompted scientific researchers to continuously explore the modification technology of activated carbon to enhance its adsorption efficiency and make it more adaptable to diverse application requirements.

[0004] The existing patent CN202111112607.5 discloses a wood-based activated carbon for vehicle carbon canisters and its preparation technology. The preparation method of the activated carbon disclosed in the present invention is as follows: 1. After mixing and screening wood powders such as peach shell powder in a certain mass ratio, add phosphoric acid for ripening, and then add an expanding agent such as 5-20 wt% of zinc chloride for kneading. 2. Blend the product with a binder such as 1%-10 wt% of sodium carboxymethyl cellulose and extrude it at high temperature. 3. The formed product is hardened at 180-250 °C for 12-36 h, and then activated at 450-700 °C for 1-4 h under a protective atmosphere. 4. After washing, drying and sieving the activated product, activated carbon particles can be obtained. The activated carbon particles prepared by this invention have a high n-butane adsorption capacity and wear resistance, and can meet the application requirements of the new generation of vehicle carbon canister activated carbon. However, in the above technical solution, the internal pore channels of the activated carbon are mainly optimized by a specific expanding agent to fit the adsorption and desorption characteristics of n-butane. It mainly relies on physical adsorption, and has disadvantages such as low adsorption selectivity and unstable adsorption performance, resulting in low adsorption efficiency of n-butane. Summary of the Invention

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

[0006] The technical solution of the present invention is realized as follows: The present invention provides a preparation method of modified activated carbon for removing n-butane, including the following steps:

[0007] S1. Impregnate coconut shell charcoal in an impregnating solution and perform activation to obtain activated carbon after activation;

[0008] S2. Disperse the activated carbon after activation in deionized water, then add polyethyleneimine and epichlorohydrin thereto, and stir and react at 60-70 °C for 4-6 h to obtain activated carbon loaded with polyethyleneimine;

[0009] S3. Disperse the activated carbon loaded with polyethyleneimine in DMF, add EDC and NHS, and then add 2,5-bis(trifluoromethyl)terephthalic acid, and stir and react 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 thereto, and stir at 70-80 °C for 3-6 h to obtain a composite modified molecular sieve;

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

[0012] In the present invention, by functionalizing activated carbon, introducing 2,5-bis(trifluoromethyl)terephthalic acid, modifying molecular sieve with sucrose and amino modification, and covalently connecting the functionalized activated carbon with the composite modified molecular sieve by glutaraldehyde, a composite material with stable structure is formed. The modified activated carbon prepared by the above technical solution not only has excellent pore structure, but also combines C-H...F hydrogen bond interaction and the selective adsorption of molecular sieve, and can efficiently and selectively remove n-butane, thereby realizing the efficient adsorption of n-butane.

[0013] On the basis of the above technical solution, preferably, step S1 specifically includes:

[0014] S11. Crushing and screening coconut shell charcoal to obtain granular charcoal with a mesh number of 30-60;

[0015] S12. Dispersing the granular charcoal in an impregnation solution for impregnation treatment, the temperature of the impregnation treatment is 30-80 °C, and the time of the impregnation treatment is 2-15 h;

[0016] S13. Heating the impregnated granular charcoal to 650-750 °C at a rate of 2.3-2.7 °C / min in a nitrogen atmosphere and activating for 1.5-2.5 h to obtain activated activated carbon.

[0017] On the basis of the above technical solution, preferably, in step S12, the mass ratio of the granular charcoal to the impregnation solution is 1:2.8-3.2, the concentration of the 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, by crushing and screening the coconut shell charcoal, the uniformity of the raw materials can be improved; 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 specific surface area and porosity of the activated carbon are further improved by the activation treatment.

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

[0020] On the basis of the above technical solution, preferably, in step S3, the mass ratio of the 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 amino groups on the polyethyleneimine molecular chain undergo ring-opening reactions with the epoxy groups of epichlorohydrin to form stable chemical bonds, thereby fixing the polyethyleneimine molecules on the surface of activated carbon and achieving preliminary functional modification of the activated carbon; then, amidation reactions occur between the residual amino groups of the activated carbon loaded with polyethyleneimine and the carboxyl groups of 2,5-bis(trifluoromethyl)terephthalic acid, thereby introducing a benzene ring structure containing trifluoromethyl groups on the surface of the activated carbon.

[0022] Based on the above technical solutions, preferably, in step S4, the preparation method of the sucrose-modified molecular sieve: dissolve sucrose in water to prepare a sucrose-modified solution, add the molecular sieve, place the mixture in an ultrasonic washer and ultrasonicate for 2 h, and then calcine in a nitrogen atmosphere to obtain the sucrose-modified molecular sieve.

[0023] Based on the above technical solutions, preferably, the addition amount of sucrose 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 the sucrose-modified molecular sieve to the aminated silane coupling agent is 5 - 8:1, and the aminated silane coupling agent is 3-aminopropyltriethoxysilane or 3-aminopropyltrimethoxysilane.

[0025] During the calcination process in a nitrogen atmosphere, sucrose undergoes pyrolytic carbonization reactions to form a uniform carbon layer on the surface and in the pores of the molecular sieve, improving the non-polarity of the molecular sieve surface; then, condensation reactions occur between the alkoxy groups in the silane coupling agent and the hydroxyl groups on the surface of the molecular sieve to introduce amino functional groups on 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 addition amount of glutaraldehyde is 5 - 15% of the mass of the functionalized activated carbon.

[0027] The functionalized activated carbon and the sucrose-modified molecular sieve are chemically compounded through a glutaraldehyde cross-linking agent to form a composite material with a synergistic adsorption effect. The two components are firmly connected 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 the adsorption-desorption process.

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

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

[0030] Beneficial effects:

[0031] (1) The modified activated carbon formed by covalently connecting functionalized activated carbon and composite modified molecular sieve through a chemical cross-linking agent in the present invention forms multiple adsorption sites and has a good effect when applied to n-butane adsorption, which 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 enhancing the adsorption capacity and selectivity of the material for n-butane;

[0032] (2) Through the functionalization modification of activated carbon in the present invention, a trifluoromethyl benzene ring group is introduced onto the surface of the activated carbon, significantly improving the adsorption selectivity of the activated carbon for n-butane. Specifically, the trifluoromethyl group containing a C-F bond forms a stable C-H...F hydrogen bond with the n-butane molecule, significantly enhancing the specificity of the adsorption effect. In addition, the chemical modification process on the surface of the activated carbon not only maintains the good pore structure of the raw material but also endows it with excellent surface characteristics, making up for the deficiency of traditional activated carbon mainly relying on physical pore adsorption from the adsorption mechanism and realizing the improvement of selectivity;

[0033] (3) Through the sucrose modification of molecular sieve and further reaction with a silane coupling agent in the present invention, a composite modified molecular sieve is prepared, significantly improving the adsorption performance and chemical reaction activity of the molecular sieve. The sucrose modification forms a uniform carbon layer on the surface of the molecular sieve through the carbonization process, optimizing the pore size distribution of the molecular sieve, enhancing the hydrophobicity of the material, and contributing to 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 It is a flow chart of the preparation method of the modified activated carbon for removing n-butane of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope 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 the particle size was 2.6 nm.

[0038] Example 1

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

[0040] S1. Crush and screen 10 g of coconut shell charcoal to obtain granular charcoal with a mesh size of 45, wash the granular charcoal with deionized water, and dry it for later use; then dissolve 30 g of potassium hydroxide in deionized water to prepare a 10% potassium hydroxide solution, disperse 10 g of the dried granular charcoal in the potassium hydroxide solution, and carry out impregnation treatment at 55 °C for 8.5 h. After the impregnation is completed, dry it in an oven at 110 °C; under nitrogen protection, raise the temperature of the atmosphere protection furnace to 700 °C at a heating rate of 2.5 °C, activate the impregnated granular charcoal for 2 h, and after the reaction is completed, cool it to room temperature to obtain activated carbon after activation;

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

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

[0043] S4. Dissolve 10 g of sucrose in water to prepare a sucrose modification solution, add 10 g of MCM-48 molecular sieve, put the mixture into an ultrasonic washer and ultrasonicate for 2 h, wash and dry, and then calcine at 550 °C for 4.5 h in a nitrogen atmosphere to obtain sucrose-modified molecular sieve;

[0044] Disperse 6.5 g of sucrose-modified molecular sieve in DMF, then add 1 g of 3-aminopropyltriethoxysilane thereto, stir at 75 °C for 4.5 h. After the reaction is completed, filter, wash, and dry to obtain a composite-modified molecular sieve;

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

[0046] Example 2

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

[0048] S1. Crush and screen 10 g of coconut shell charcoal to obtain granular charcoal with a mesh number of 30, wash the granular charcoal with deionized water, and dry it for standby; then dissolve 28 g of sodium hydroxide in deionized water to prepare a 5% sodium hydroxide solution, disperse 10 g of the dried granular charcoal in the sodium hydroxide solution, and soak it at 30 °C for 15 h. After the soaking is completed, dry it in an oven at 110 °C; under nitrogen protection, raise the temperature of the atmosphere protection furnace to 650 °C at a heating rate of 2.3 °C, and activate the soaked granular charcoal for 2.5 h. After the reaction is completed, cool to room temperature to obtain activated carbon after activation;

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

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

[0051] S4. Dissolve 8 g of sucrose in water to prepare a sucrose-modified solution, add 10 g of MCM-48 molecular sieve, put the mixed solution into an ultrasonic washer and ultrasonicate for 2 h, wash and dry, and then calcine at 450 °C for 6 h under a nitrogen atmosphere to obtain sucrose-modified molecular sieve;

[0052] Disperse 5 g of sucrose-modified molecular sieve in DMF, then add 1 g of 3-aminopropyltriethoxysilane thereto, stir at 70 °C for 6 h, after the reaction is completed, filter, wash, and dry to obtain a composite-modified molecular sieve;

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

[0054] Example 3

[0055] This example provides a preparation method of modified activated carbon for removing n-butane, including the following steps:

[0056] S1. Crush and screen 10 g of coconut shell charcoal to obtain granular charcoal with a mesh number of 60, wash the granular charcoal with deionized water, and dry it for standby; then dissolve 32 g of acetic acid in deionized water to prepare a 15% acetic acid solution, disperse 10 g of the dried granular charcoal in the acetic acid solution, impregnate at 80 °C for 2 h, and dry it in an oven at 110 °C after impregnation; under nitrogen protection, raise the temperature of the atmosphere protection furnace to 750 °C at a heating rate of 2.7 °C, activate and react the impregnated granular charcoal for 1.5 h, after the reaction is completed, cool to room temperature to obtain activated carbon after activation;

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

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

[0059] S4. Dissolve 12 g of sucrose in water to prepare a sucrose-modified solution, add 10 g of MCM-48 molecular sieve, put the mixed solution into an ultrasonic washer and ultrasonicate for 2 h, wash and dry, and then calcine at 650 °C for 3 h in a nitrogen atmosphere to obtain sucrose-modified molecular sieve;

[0060] Disperse 8 g of sucrose-modified molecular sieve in DMF, then add 1 g of 3-aminopropyltriethoxysilane thereto, stir at 80 °C for 3 h, after the reaction is completed, filter, wash, and dry to obtain a composite-modified molecular sieve;

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

[0062] Comparative Example 1

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

[0064] S1. Crush and screen 10 g of coconut shell charcoal to obtain granular charcoal with a mesh size of 45, wash the granular charcoal with deionized water, and dry it for standby; then dissolve 30 g of potassium hydroxide in deionized water to prepare a 10% potassium hydroxide solution, disperse 10 g of the dried granular charcoal in the potassium hydroxide solution, impregnate at 55 °C for 8.5 h, and after the impregnation is completed, dry it in an oven at 110 °C; under nitrogen protection, raise the temperature of the atmosphere protection furnace to 700 °C at a heating rate of 2.5 °C, activate and react the impregnated granular charcoal for 2 h, and after the reaction is completed, cool to room temperature to obtain the activated activated carbon;

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

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

[0067] Comparative Example 2

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

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

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

[0071] Disperse 6.5 g of sucrose-modified molecular sieve in DMF, then add 1 g of 3-aminopropyltriethoxysilane thereto, stir at 75 °C for 4.5 h. After the reaction is completed, filter, wash, and dry to obtain a composite-modified molecular sieve;

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

[0073] Comparative Example 3

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

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

[0076] S4. Dissolve 10 g of sucrose in water to prepare a sucrose-modified solution, add 10 g of MCM-48 molecular sieve, put the mixture into an ultrasonic washer and ultrasonicate for 2 h, wash and dry, and then calcine at 550 °C for 4.5 h in a nitrogen atmosphere to obtain a sucrose-modified molecular sieve;

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

[0078] Comparative Example 4

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

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

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

[0082] Performance detection

[0083] The modified activated carbons prepared in the examples and comparative examples are 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] Height of carbon layer: (10 ± 0.2) cm.

[0085] Flow rate of n-butane: (250 ± 5) mL / min.

[0086] Flow rate of nitrogen or air: (300 ± 5) mL / min.

[0087] Adsorption and desorption temperature: (25 ± 0.5) °C

[0088] Result calculation:

[0089] Butane working capacity (BWC)

[0090]

[0091] In the formula:

[0092] BWC V : Butane working volume capacity of activated carbon, unit: gram per hundred milliliters (g / 100ml);

[0093] ρ: Apparent density or packing specific gravity of the activated carbon sample, unit: gram per milliliter (g / ml);

[0094] m1: Mass of the sample tube together with the stopper, unit: gram (g);

[0095] m2: Mass of the sample tube with carbon and stopper before adsorption, unit: gram (g);

[0096] m3: Mass of the sample tube with carbon, n-butane and stopper after saturated adsorption, unit: gram (g);

[0097] m4: Mass of the sample tube with carbon, un-desorbed n-butane and stopper after desorption, unit: gram (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 can be seen from Table 1, the modified activated carbon prepared by the technical solution of the present invention has a good n-butane adsorption effect, and can greatly improve the butane working volume capacity of the activated carbon compared with the technical solution of the comparative example.

[0102] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a modified activated carbon for removing n-butane, characterized in that: It includes the following steps: S1. Impregnate coconut shell charcoal in an impregnation solution and activate it to obtain activated activated carbon; S2. Disperse the activated activated carbon in deionized water, then add polyethyleneimine and epichlorohydrin thereto, and stir and react at 60 - 70 °C for 4 - 6 h 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, and stir and react at room temperature for 8 - 10 h to obtain functionalized activated carbon; S4. Disperse the sucrose - modified molecular sieve in DMF, then add an amino - functionalized silane coupling agent thereto, and stir at 70 - 80 °C for 3 - 6 h to obtain a composite - modified molecular sieve; S5. Disperse the composite - modified molecular sieve and the functionalized activated carbon in water, add a sodium bicarbonate solution to adjust the pH to 7.5 - 9, add glutaraldehyde, and stir and react at 40 - 50 °C for 8 - 12 h. After the reaction, filter, wash, and dry to obtain modified activated carbon.

2. The preparation method of a modified activated carbon for removing n-butane according to claim 1, characterized in that: Step S1 specifically includes: S11. Crush and screen coconut shell charcoal to obtain granular charcoal with a mesh size of 30 - 60 meshes; S12. Disperse the granular charcoal in the impregnation solution for impregnation treatment. The temperature of the impregnation treatment is 30 - 80 °C, and the time of the impregnation treatment is 2 - 15 h; S13. Under a nitrogen atmosphere, heat the impregnated granular charcoal to 650 - 750 °C at a rate of 2.3 - 2.7 °C / min, and carry out an activation reaction for 1.5 - 2.5 h to obtain activated activated carbon.

3. The preparation method of a modified activated carbon for removing n-butane according to claim 2, characterized in that: In step S12, the mass ratio of the granular charcoal to the impregnation solution is 1:2.8 - 3.2, the concentration of the 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 preparation method of a modified activated carbon for removing n-butane according to claim 1, characterized in that: In step S2, the mass ratio of the activated activated carbon, polyethyleneimine, and epichlorohydrin is 6 - 9:4 - 6:2 - 4.

5. The preparation method of a modified activated carbon for removing n-butane as described in claim 1, characterized in that: In step S3, the mass ratio of the 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 preparation method of a modified activated carbon for removing n-butane according to claim 1, characterized in that: In step S4, the preparation method of the sucrose - modified molecular sieve: Dissolve sucrose in water to prepare a sucrose - modified solution, add a molecular sieve, put the mixture into an ultrasonic washer and ultrasonicate for 2 h, and then calcine under a nitrogen atmosphere to obtain the sucrose - modified molecular sieve.

7. The preparation method of a modified activated carbon for removing n-butane according to claim 6, characterized in that: The addition amount of sucrose is 0.8 - 1.2 times the mass of the molecular sieve, and the molecular sieve is MCM - 48.

8. The preparation method of a modified activated carbon for removing n-butane according to claim 1, characterized in that: In step S4, the mass ratio of the sucrose - modified molecular sieve to the amino - functionalized silane coupling agent is 5 - 8:1, and the amino - functionalized silane coupling agent is 3 - aminopropyltriethoxysilane or 3 - aminopropyltrimethoxysilane.

9. The preparation method of a modified activated carbon for removing n-butane according to 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 addition amount of glutaraldehyde 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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