Preparation method of biomass-based activated carbon for carbon tank

Abstract

The invention belongs to the technical field of activated carbon, and particularly relates to a preparation method of biomass-based activated carbon for a carbon tank. The preparation method comprises the following steps: (1) uniformly mixing 40-45 parts by weight of powdered activated carbon, 19-23 parts by weight of modified phenolic resin, 5-10 parts by weight of a binder and 55-60 parts by weight of water, and kneading to obtain activated carbon mud; (2) extruding the activated carbon mud into granular activated carbon mud, and drying to obtain dried granular activated carbon; (3) in a nitrogen atmosphere, heating the dried granular activated carbon to 250-260 DEG C, and keeping the temperature for 1-1.5 h; and heating to 500-540 DEG C, preserving heat for 9-12 hours, finally heating to 700-760 DEG C, and preserving heat for 5-7 hours to obtain the biomass-based activated carbon for the carbon tank. The biomass-based activated carbon for the carbon tank prepared by the invention simultaneously realizes high adsorption and low impedance, and is high in strength.

Description

Technical Field

[0001] The invention belongs to the technical field of activated carbon, and in particular relates to a method for preparing biomass-based activated carbon for a carbon canister. Background Art

[0002] As a key component in the fuel evaporation control system of gasoline vehicles, the carbon canister's main function is to reduce the fuel vapor emitted by the fuel system into the atmosphere, especially to prevent gasoline vapor from escaping directly into the air, so as to achieve the purpose of energy conservation and environmental protection. This process relies on the core material inside the carbon canister - activated carbon, which can efficiently adsorb the fuel vapor escaping from the fuel tank and recycle it for reuse. In order to ensure optimal performance, the molded activated carbon used in the carbon canister needs to meet a series of strict technical requirements. First, it must have an extremely high specific surface area, which means that the activated carbon has a large surface area per unit mass, which can provide more pore structures to adsorb gasoline molecules. High specific surface area and developed pore structure help improve adsorption efficiency and ensure that fuel vapor can be effectively captured under various working conditions. Activated carbon also needs to have sufficient mechanical strength to withstand various physical stresses that may be encountered during installation and use, including vibration, impact, etc. This is because carbon canisters are usually located at the bottom of the vehicle or in the engine compartment, which are easily affected by the external environment. High-strength activated carbon not only ensures its structural stability, but also extends the service life of the carbon canister and reduces maintenance requirements.

[0003] At present, the activated carbon used in automobile carbon canisters in my country is prepared from sawdust as raw material, which has the following defects: (1) Low strength: During the production process, sawdust is mixed with a chemical activator (such as phosphoric acid) and then extruded and shaped, followed by high-temperature carbonization and activation. This series of process steps will cause the formed sawdust material to shrink and crack significantly. (2) Poor adsorption and desorption performance: The existing process adopts a production process of first forming and then activating. The sawdust is screened and dried, and then phosphoric acid solution is added to stir the core to make wood particles. The product obtained by carbonization and activation has poor pore structure and pore size distribution uniformity; (3) Low durability and service life: Activated carbon will be affected by temperature changes, humidity, vibration and other factors in the automobile environment, which may gradually reduce its performance. In order to extend the service life of the carbon canister, it is necessary to improve the durability of activated carbon so that it can maintain high adsorption capacity for a long time.

[0004] The activated carbon with high adsorption performance prepared by the prior art generally has high ventilation impedance, or the activated carbon with low ventilation impedance has poor adsorption performance. Chinese patent CN201710531774.0 discloses wood granular activated carbon for automobile carbon canisters and its preparation method, and the preparation method includes two main processes of preparing wood activated carbon powder and preparing wood granular activated carbon.

[0005] Therefore, there is an urgent need for a method for preparing biomass-based activated carbon for carbon canisters. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing biomass-based activated carbon for a carbon canister.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing biomass-based activated carbon for a carbon canister comprises the following steps:

[0009] (1) 40-45 parts by weight of powdered activated carbon, 19-23 parts by weight of modified phenolic resin, 5-10 parts by weight of a binder and 55-60 parts by weight of water are uniformly mixed and kneaded to obtain activated carbon mud;

[0010] (2) extruding the activated carbon mud into granular activated carbon mud, and drying it to obtain dry granular activated carbon;

[0011] (3) Under a nitrogen atmosphere, the dried granular activated carbon is heated to 250-260°C at a heating rate of 5-10°C / min and kept warm for 1-1.5 h; heated to 500-540°C at a heating rate of 10-15°C / min and kept warm for 9-12 h; and finally heated to 700-760°C at a heating rate of 10-15°C / min and kept warm for 5-7 h to obtain biomass-based activated carbon for carbon canisters.

[0012] Furthermore, the powdered activated carbon comprises coconut shell powdered activated carbon I, coconut shell powdered activated carbon II and coconut shell powdered activated carbon III in a weight ratio of 1: (0.2-0.5): (1.4-1.7); the particle size of coconut shell powdered activated carbon I is 5-20 μm, and the specific surface area is 800 m 2 / g; the particle size of coconut shell powdered activated carbon II is 80-100μm, and the specific surface area is 1200m2 / g; the particle size of coconut shell powdered activated carbon III is 120-160μmmm, and the specific surface area is 1400m 2 / g. .

[0013] At present, most of the powdered activated carbons produced by activated carbon manufacturers on the market have a specific surface area of ​​less than 1500. The present invention mixes the existing activated carbon on the market with modified phenolic resin by proportioning, and the activated carbon prepared has a higher specific surface area. The combination of activated carbon with different parameters and modified phenolic resin makes the final product have a wider pore size distribution, covering multiple scales from micropores to macropores. This optimized pore size distribution not only increases the specific surface area, but also enhances the adsorption capacity of activated carbon.

[0014] Furthermore, the preparation method of the modified phenolic resin comprises the following steps:

[0015] (1) mixing graphene oxide and deionized water, and ultrasonicating to obtain a mixed solution;

[0016] (2) 4-6 parts by weight of phenol, 6-8 parts by weight of formaldehyde, 0.3-0.6 parts by weight of NaOH and 60-70 parts by weight of graphene oxide solution are mixed evenly, heated to 65-70° C., kept warm for reaction for 1.5-1.8 hours, then heated to 85-90° C., kept warm for reaction for 1.5-2 hours, to obtain a modified phenolic resin.

[0017] Furthermore, the graphene oxide has a thickness of 0.55-1.2 nm, a diameter of 0.5-3 μm, and a number of layers of 1-5, and is purchased from Beijing Dekedaojin Technology Co., Ltd.

[0018] The present invention can improve the ventilation impedance of biomass-based activated carbon for carbon canisters by modifying phenolic resin with graphene oxide. The introduction of graphene oxide in phenolic resin can form more micropores, mesopores and macropores during the carbonization process. The two-dimensional sheet structure of graphene oxide can be evenly dispersed in the phenolic resin, ensuring the uniform distribution of pores throughout the activated carbon. This uniform pore distribution allows gas to pass through the activated carbon bed more smoothly, reducing the possibility of local blockage and further reducing ventilation impedance. An appropriate amount of micropores, mesopores and macropores to ensure that gas molecules can smoothly enter the micropores for adsorption, while quickly diffusing through the mesopores and macropores. This optimized pore size distribution not only improves the adsorption efficiency of the activated carbon, but also reduces the resistance to gas flow and reduces ventilation impedance.

[0019] Further, graphene oxide and deionized water in a weight ratio of 1:(7-9) are mixed and ultrasonicated for 0.5 to 1 h to obtain a mixed solution.

[0020] Furthermore, in the step (1), kneading is performed at 40-50° C. for 1-1.5 hours.

[0021] Furthermore, in the step (2), the activated carbon mud is extruded into granular activated carbon mud at 25-30°C.

[0022] Furthermore, in the step (2), the granular activated carbon mud is dried at 90-100° C. for 1-2 hours.

[0023] Furthermore, the binder in step (1) comprises silica sol and aluminum dihydrogen phosphate in a weight ratio of 1: (1.3-1.6).

[0024] Furthermore, the activated carbon mud is extruded into cylindrical particles in step (2).

[0025] Furthermore, in the step (2), the cylindrical shape has a diameter of 2-4 mm and a length of 5-8 mm.

[0026] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0027] 1. The present invention mixes the existing activated carbon on the market with modified phenolic resin through proportioning, and the prepared activated carbon has a higher specific surface area.

[0028] 2. The present invention can improve the ventilation impedance of biomass-based activated carbon for carbon canisters by modifying phenolic resin with graphene oxide, and at the same time improve the strength of activated carbon. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The raw materials used in the following examples of the present invention are all commercially available products:

[0031] Silica sol, brand Kangda additives, model JN-20.

[0032] Example 1

[0033] This embodiment provides a method for preparing biomass-based activated carbon for a carbon canister, characterized in that it comprises the following steps:

[0034] (1) 42 parts by weight of powdered activated carbon, 20 parts by weight of modified phenolic resin, 7 parts by weight of a binder and 58 parts by weight of water were uniformly mixed and kneaded at 45° C. for 1.2 hours to obtain activated carbon sludge; the binder included silica sol and aluminum dihydrogen phosphate in a weight ratio of 1:1.4.

[0035] (2) Extruding activated carbon mud into granular activated carbon mud at 27° C., and drying the granular activated carbon mud at 100° C. for 1.5 hours to obtain dry granular activated carbon; the activated carbon mud is cylindrical; the cylindrical circular diameter is 3 mm and the length is 6 mm.

[0036] (3) Under a nitrogen atmosphere, the dried granular activated carbon was heated to 255°C at a heating rate of 7°C / min and kept warm for 1.2 h; heated to 520°C at a heating rate of 12°C / min and kept warm for 10 h; and finally heated to 730°C at a heating rate of 12°C / min and kept warm for 6 h to obtain biomass-based activated carbon for carbon canisters.

[0037] The powdered activated carbon includes coconut shell powdered activated carbon I, coconut shell powdered activated carbon II and coconut shell powdered activated carbon III in a weight ratio of 1:0.4:1.6; the particle size of coconut shell powdered activated carbon I is 5-20 μm, and the specific surface area is 800 m 2 / g; the particle size of coconut shell powdered activated carbon II is 80-100μm, and the specific surface area is 1200m2 / g; the particle size of coconut shell powdered activated carbon III is 120-160μmmm, and the specific surface area is 1400m 2 / g.

[0038] The preparation method of the modified phenolic resin comprises the following steps:

[0039] S1: mixing graphene oxide and deionized water in a weight ratio of 1:8, and ultrasonicating for 0.7 h to obtain a mixed solution (graphene oxide solution);

[0040] The graphene oxide has a thickness of 0.55-1.2 nm, a diameter of 0.5-3 μm, and a number of 1-5 layers, and is purchased from Beijing Dekedaojin Technology Co., Ltd.

[0041] S2: Take 5 parts by weight of phenol, 7 parts by weight of formaldehyde, 0.4 parts by weight of NaOH and 65 parts by weight of graphene oxide solution, mix them evenly, heat them to 67° C., keep them warm for 1.6 hours, then heat them to 88° C., keep them warm for 1.7 hours to obtain modified phenolic resin.

[0042] Example 2

[0043] A method for preparing biomass-based activated carbon for a carbon canister, characterized by comprising the following steps:

[0044] (1) 40 parts by weight of powdered activated carbon, 23 parts by weight of modified phenolic resin, 5 parts by weight of a binder and 60 parts by weight of water were uniformly mixed and kneaded at 40° C. for 1.5 hours to obtain activated carbon sludge; the binder included silica sol and aluminum dihydrogen phosphate in a weight ratio of 1:1.3.

[0045] (2) Extruding activated carbon mud into granular activated carbon mud at 25° C., and drying the granular activated carbon mud at 100° C. for 2 hours to obtain dry granular activated carbon; the activated carbon mud is cylindrical; the cylindrical circular diameter is 3 mm and the length is 6 mm.

[0046] (3) Under a nitrogen atmosphere, the dried granular activated carbon was heated to 250°C at a heating rate of 10°C / min and kept warm for 1.5 h; heated to 540°C at a heating rate of 10°C / min and kept warm for 9 h; and finally heated to 700°C at a heating rate of 15°C / min and kept warm for 7 h to obtain biomass-based activated carbon for carbon canisters.

[0047] The powdered activated carbon includes coconut shell powdered activated carbon I, coconut shell powdered activated carbon II and coconut shell powdered activated carbon III in a weight ratio of 1:0.2:1.4; the particle size of coconut shell powdered activated carbon I is 5-20 μm, and the specific surface area is 800 m 2 / g; the particle size of coconut shell powdered activated carbon II is 80-100μm, and the specific surface area is 1200m2 / g; the particle size of coconut shell powdered activated carbon III is 120-160μmmm, and the specific surface area is 1400m 2 / g.

[0048] The preparation method of the modified phenolic resin comprises the following steps:

[0049] S1: mixing graphene oxide and deionized water in a weight ratio of 1:9, and ultrasonicating for 1 h to obtain a mixed solution (graphene oxide solution);

[0050] The graphene oxide has a thickness of 0.55-1.2 nm, a diameter of 0.5-3 μm, and a number of 1-5 layers, and is purchased from Beijing Dekedaojin Technology Co., Ltd.

[0051] S2: Take 5 parts by weight of phenol, 8 parts by weight of formaldehyde, 0.3 parts by weight of NaOH and 70 parts by weight of graphene oxide solution, mix them evenly, heat them to 70°C, keep them warm for 1.5 hours, then heat them to 90°C, keep them warm for 1.5 hours to obtain modified phenolic resin.

[0052] Comparative Example 1

[0053] The difference between this comparative example and Example 1 is that the powdered activated carbon comprises coconut shell powdered activated carbon I, coconut shell powdered activated carbon II and coconut shell powdered activated carbon III in a weight ratio of 1:1:1; the particle size of coconut shell powdered activated carbon I is 5-20 μm, and the specific surface area is 800 m 2 / g; the particle size of coconut shell powdered activated carbon II is 80-100μm, and the specific surface area is 1200m 2 / g; the particle size of coconut shell powdered activated carbon III is 120-160μmmm, and the specific surface area is 1400m 2 / g.

[0054] Comparative Example 2

[0055] The difference between this comparative example and Example 1 is that the particle size of the powdered activated carbon is 80-100 μm, and the specific surface area is 1200 m 2 / g.

[0056] Comparative Example 3

[0057] The difference between this comparative example and Example 1 is that the phenolic resin is not modified.

[0058] The preparation method of the phenolic resin comprises the following steps: taking 5 parts by weight of phenol, 7 parts by weight of formaldehyde, 0.4 parts by weight of NaOH and 65 parts by weight of graphene oxide solution, mixing them evenly, heating them to 67° C., keeping the temperature for reaction for 1.6 hours, then heating them to 88° C., keeping the temperature for reaction for 1.7 hours, and obtaining the phenolic resin.

[0059] Comparative Example 4

[0060] The difference between this comparative example and Example 1 is: under a nitrogen atmosphere, the dried granular activated carbon is heated to 260°C at a heating rate of 2°C / min and kept warm for 3.2 hours; heated to 560°C at a heating rate of 7°C / min and kept warm for 10 hours; finally, heated to 790°C at a heating rate of 7°C / min and kept warm for 4 hours to obtain biomass-based activated carbon for carbon canisters.

[0061] Comparative Example 5

[0062] The difference between this comparative example and Example 1 is that under a nitrogen atmosphere, the dried granular activated carbon is heated to 230°C at a heating rate of 7°C / min and kept warm for 1.2 hours; it is heated to 700°C at a heating rate of 12°C / min and kept warm for 16 hours to obtain biomass-based activated carbon for carbon canisters.

[0063] Comparative Example 6

[0064] The difference between this comparative example and Example 1 is that the graphene oxide has a thickness of 3 to 5 nm, a diameter of 18 to 20 μm, and 1 to 3 layers.

[0065] Performance Testing

[0066] The performance of the biomass-based activated carbon for carbon canisters prepared in Examples 1-2 and Comparative Examples 1-6 was tested.

[0067] Refer to GB / T19587-2017 to test specific surface area.

[0068] Refer to GB / T20449-2006 to test butane working capacity.

[0069] Refer to ASTM D3802 for strength testing.

[0070] The ventilation impedance at a flow rate of 70 L / min was measured with reference to GB / T32560-2016.

[0071] Table 1 Performance test results

[0072]

[0073] It can be seen from the above performance test results that the biomass-based activated carbon for carbon canisters of Examples 1-2 has excellent comprehensive performance, especially the comprehensive performance of Example 1 is the most outstanding, which is mainly due to the synergistic effect between the components.

[0074] However, the comparative examples are obviously inferior to the embodiments in the corresponding performance tests because they do not adopt the necessary technical solutions. In comparative examples 1 and 2, the ratio of powdered activated carbon is changed, and it can be seen that the specific surface area of ​​the product decreases. In comparative example 3, the phenolic resin is not modified, the ventilation impedance of the product becomes higher, and the strength becomes worse. In comparative example 4, the carbonization conditions are changed, and the comprehensive performance of the product decreases to varying degrees, indicating that the carbonization conditions of the present invention have an impact on the performance of the product. In comparative example 6, the parameters of graphene oxide are different, and the ventilation impedance of the product becomes higher. The above experimental results further prove the importance of the technical solution defined in the present invention for its technical effect.

[0075] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing biomass-based activated carbon for a carbon canister, characterized in that: The following steps are involved: (1) 40-45 parts by weight of powdered activated carbon, 19-23 parts by weight of modified phenolic resin, 5-10 parts by weight of a binder and 55-60 parts by weight of water are uniformly mixed and kneaded to obtain activated carbon mud; (2) extruding the activated carbon mud into granular activated carbon mud, and drying it to obtain dry granular activated carbon; (3) Under a nitrogen atmosphere, the dried granular activated carbon is heated to 250-260°C at a heating rate of 5-10°C / min and kept warm for 1-1.5 h; heated to 500-540°C at a heating rate of 10-15°C / min and kept warm for 9-12 h; and finally heated to 700-760°C at a heating rate of 10-15°C / min and kept warm for 5-7 h to obtain biomass-based activated carbon for carbon canisters.

2. The method for preparing biomass-based activated carbon for carbon canisters according to claim 1, characterized in that: The powdered activated carbon comprises coconut shell powdered activated carbon I, coconut shell powdered activated carbon II and coconut shell powdered activated carbon III in a weight ratio of 1: (0.2-0.5): (1.4-1.7); the particle size of coconut shell powdered activated carbon I is 5-20 μm, and the specific surface area is 800 m 2 / g; the particle size of coconut shell powdered activated carbon II is 80-100μm, and the specific surface area is 1200m 2 / g; the particle size of coconut shell powdered activated carbon III is 120-160μmmm, and the specific surface area is 1400m 2 / g.

3. The method for preparing biomass-based activated carbon for carbon canisters according to claim 1, characterized in that: The preparation method of the modified phenolic resin comprises the following steps: S1: mixing graphene oxide and deionized water, and ultrasonicating to obtain a mixed solution; S2: Take 4-6 parts by weight of phenol, 6-8 parts by weight of formaldehyde, 0.3-0.6 parts by weight of NaOH and 60-70 parts by weight of graphene oxide solution, mix them evenly, heat them to 65-70°C, keep them warm for 1.5-1.8h, then heat them to 85-90°C, keep them warm for 1.5-2h to obtain modified phenolic resin.

4. The method for preparing biomass-based activated carbon for carbon canisters according to claim 1, characterized in that: The graphene oxide has a thickness of 0.55 to 1.2 nm, a diameter of 0.5 to 3 μm, and a number of layers of 1 to 5.

5. The method for preparing biomass-based activated carbon for carbon canisters according to claim 1, characterized in that: Graphene oxide and deionized water in a weight ratio of 1:(7-9) were mixed and ultrasonicated for 0.5 to 1 h to obtain a mixed solution.

6. The method for preparing biomass-based activated carbon for carbon canisters according to claim 1, characterized in that: In the step (1), kneading is performed at 40-50° C. for 1-1.5 hours.

7. The method for preparing biomass-based activated carbon for carbon canisters according to claim 1, characterized in that: In the step (2), the activated carbon mud is extruded into granular activated carbon mud at 25-30°C.

8. The method for preparing biomass-based activated carbon for carbon canisters according to claim 1, characterized in that: In the step (2), the granular activated carbon mud is dried at 90-100° C. for 1-2 hours.

9. The method for preparing biomass-based activated carbon for carbon canisters according to claim 1, characterized in that: The binder in step (1) comprises silica sol and aluminum dihydrogen phosphate in a weight ratio of 1: (1.3-1.6).

10. The method for preparing biomass-based activated carbon for carbon canisters according to claim 1, characterized in that: The activated carbon mud is extruded into cylindrical particles in step (2); the cylindrical particles have a circular diameter of 2-4 mm and a length of 5-8 mm.

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