阅读说明：本技术 改性活性炭及活性炭改性方法 (Modified activated carbon and activated carbon modification method ) 是由 常超 杨阳 徐冬 高腾飞 孙振新 徐妍 于 2020-12-30 设计创作，主要内容包括：本发明涉及活性炭改性技术领域,公开了一种活性炭改性方法,该方法在惰性气体保护下进行：1)将活性炭进行第一次热处理,得到改性活性炭I；2)将改性活性炭I与聚亚胺混合后进行第二次热处理,得到改性活性炭II；3)将改性活性炭II与硅氧烷混合后进行第三次加热处理,得到改性活性炭。本发明通过调整聚亚胺和硅氧烷的用量以及热处理温度调节活性炭性能,不仅改性过程简单,操作方便,而且能显著提高改性活性炭的二氧化碳吸附容量及耐水抗磨性能。(The invention relates to the technical field of active carbon modification, and discloses an active carbon modification method, which is carried out under the protection of inert gas: 1) carrying out first heat treatment on the activated carbon to obtain modified activated carbon I; 2) mixing the modified activated carbon I with polyimide, and then carrying out secondary heat treatment to obtain modified activated carbon II; 3) and mixing the modified activated carbon II with siloxane, and then carrying out third heating treatment to obtain the modified activated carbon. The invention adjusts the performance of the activated carbon by adjusting the dosage of the polyimide and the siloxane and the heat treatment temperature, not only has simple modification process and convenient operation, but also can obviously improve the carbon dioxide adsorption capacity and the water-resistant and wear-resistant performance of the modified activated carbon.)

1. A modified method of activated carbon, which is carried out under the protection of inert gas, comprises the following steps:

(1) carrying out first heat treatment on the activated carbon to obtain modified activated carbon I;

(2) mixing the modified activated carbon I with polyimide, and then carrying out secondary heat treatment to obtain modified activated carbon II;

(3) and mixing the modified activated carbon II with siloxane, and then carrying out third heating treatment to obtain the modified activated carbon.

2. The modification method according to claim 1, wherein in the step (1), the activated carbon is shell activated carbon selected from at least one of coconut shell activated carbon, peach shell activated carbon, walnut shell activated carbon and jujube shell activated carbon.

3. The modification method according to claim 1 or 2, wherein, in the step (1), the treatment temperature of the first heat treatment is 550-750 ℃, preferably 600-700 ℃; the treatment time is 1-3h, preferably 1.5-2.5 h.

4. The modification method according to any one of claims 1 to 3, wherein in step (2), the polyethyleneimine is a polyethyleneimine and/or a polyetherimide, preferably a polyethyleneimine.

5. The modification method according to any one of claims 1 to 4, wherein in the step (2), the mass ratio of the modified activated carbon I to the polyimine is 1: 0.01 to 1.2, preferably 1: 0.2-0.4.

6. The modification method according to any one of claims 1 to 5, wherein, in the step (2), the treatment temperature of the second heat treatment is 140-200 ℃, preferably 160-180 ℃, and the heating time is 1-3h, preferably 1.5-2 h.

7. The modification method according to any one of claims 1 to 6, wherein in the step (3), the siloxane is at least one selected from polydimethylsiloxane, cyclomethicone, aminosiloxane and polymethylphenylsiloxane, and is preferably polydimethylsiloxane.

8. The modification method according to any one of claims 1 to 7, wherein in the step (3), the mass ratio of the modified activated carbon II to the siloxane is 1: 0.001-0.3, preferably 1: 0.005-0.01.

9. The modification method according to any one of claims 1 to 8, wherein in the step (3), the treatment temperature of the third heat treatment is 370-450 ℃, preferably 390-410 ℃, and the heating time is 1-3h, preferably 1.5-2.5 h.

10. A modified activated carbon prepared by the modification method of claims 1-9.

Technical Field

The invention relates to the technical field of active carbon modification, in particular to modified active carbon and an active carbon modification method.

Background

The activated carbon has strong adsorbability, no toxicity, environmental protection and low price, and is a common adsorption material. In the field of pressure swing adsorption of tail flue gas carbon dioxide of a thermal power plant, due to the scouring action of water-containing flue gas, the abrasion loss of activated carbon is generally serious, and a large amount of activated carbon powder is brought into a pressure swing adsorption program control valve by the flue gas, so that the valve is easy to block and damage. Therefore, in order to be suitable for the working environment, the activated carbon needs to have stronger water and abrasion resistance.

Before the activated carbon is not modified, the problems of low strength, easy abrasion and poor water resistance generally exist. The conventional common modification methods for the activated carbon comprise surface oxidation modification, surface reduction modification, loaded metal modification, microwave modification and the like, the modification mainly changes the physical and chemical properties of the activated carbon, the focus is on selectivity and adsorption capacity, and reports of increasing the adsorption capacity and the water and wear resistance at the same time are not found at present.

CN103769065A discloses an active carbon modification method for improving the adsorption rate of nonpolar molecules, and the preparation method of the material comprises the steps of firstly placing common active carbon in a high-temperature oven to be heated in an environment with the volume fraction of vacuum, pure nitrogen or oxygen being lower than 5%, then placing Polydimethylsiloxane (PDMS) and the active carbon heated by the oven into the oven according to a certain mass ratio, and heating the active carbon after sealing. Although the method can effectively solve the problem that common activated carbon preferentially adsorbs polar molecules and improve the adsorption rate of non-polar molecules, the method cannot break through the water resistance and wear resistance of the activated carbon body and can also cause the reduction of the adsorption quantity of the activated carbon.

Therefore, it is highly desirable to provide a method for modifying activated carbon, which is used to prepare activated carbon with high adsorption capacity and good water resistance and abrasion resistance.

Disclosure of Invention

The invention aims to solve the problems of low strength, easy abrasion, poor water resistance and low carbon dioxide adsorption capacity of the active carbon in the prior art, and provides the active carbon modification method which has the advantages of simple operation, good water resistance and wear resistance of the prepared active carbon and high carbon dioxide adsorption capacity.

In order to achieve the above object, a first aspect of the present invention provides an activated carbon modification method, which is performed under an inert gas atmosphere, and comprises the following steps:

(1) carrying out first heat treatment on the activated carbon to obtain modified activated carbon I;

(2) mixing the modified activated carbon I with polyimide, and then carrying out secondary heat treatment to obtain modified activated carbon II;

(3) and mixing the modified activated carbon II with siloxane, and then carrying out third heating treatment to obtain the modified activated carbon.

In a second aspect, the present invention provides a modified activated carbon prepared by the modification method of the first aspect of the present invention.

Through the technical scheme, the beneficial technical effects obtained by the invention are as follows: the active carbon modification method of the invention utilizes siloxane and polyimide for modification, has simple modification process and convenient operation, and can obviously improve the carbon dioxide adsorption capacity and the water and abrasion resistance of the modified active carbon.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a modified method of activated carbon, which is carried out under the protection of inert gas and comprises the following steps:

(1) carrying out first heat treatment on the activated carbon to obtain modified activated carbon I;

(2) mixing the modified activated carbon I with polyimide, and then carrying out secondary heat treatment to obtain modified activated carbon II;

(3) and mixing the modified activated carbon II with siloxane, and then carrying out third heating treatment to obtain the modified activated carbon.

The inert gas in the present invention refers to a gas that does not chemically react with activated carbon, polyimide and siloxane, and particularly does not contain oxygen or contains oxygen in an amount of 0.5% by volume or less, and may be, for example, nitrogen, argon or helium.

The inventor of the invention discovers through research that a layer of polyimide film is formed on the surface of the activated carbon in an anaerobic environment, then a layer of siloxane film is formed on the surface of the activated carbon, and the polyimide film and the siloxane film act together, so that the adsorption capacity of the activated carbon on carbon dioxide can be obviously increased, and the water resistance and the wear resistance of the activated carbon can be obviously improved.

In step (1):

in a preferred embodiment, the activated carbon is shell activated carbon, and is selected from at least one of coconut shell activated carbon, peach shell activated carbon, walnut shell activated carbon and jujube shell activated carbon, and is further preferably coconut shell activated carbon.

In a preferred embodiment, the coconut shell activated carbon has a particle size of 2-5mm, an iodine value of 900mg/L or more, a hardness of 92% or more, and an ash content of 5-10%.

In a preferred embodiment, the first heat treatment is carried out at a temperature of 550-750 ℃, preferably 600-700 ℃, and for a time of 1-3h, preferably 1.5-2.5 h.

In a preferred embodiment, after the first heat treatment is finished, the temperature is reduced to room temperature to obtain modified activated carbon I.

In step (2):

in a preferred embodiment, the polyimide is a polyethyleneimine and/or a polyetherimide, preferably a polyethyleneimine.

The polyethyleneimine is not particularly limited in the present invention, and is preferably a polyethyleneimine having an average molecular weight (LS) of 200,000-300,000, and more preferably a branched polyethyleneimine having an average molecular weight (LS) -270,000.

In a preferred embodiment, the mass ratio of the modified activated carbon I to the polyimide is 1: 0.01 to 1.2, preferably 1: 0.2-0.4.

In a preferred embodiment, the treatment temperature of the second heat treatment is 140-.

And through the second heat treatment, the polyimide can form a layer of polyimide film on the surface of the activated carbon, so that the activated carbon is modified.

In step (3):

in a preferred embodiment, the silicone is selected from at least one of polydimethylsiloxane, cyclomethicone, aminosiloxane and polymethylphenylsiloxane, preferably polydimethylsiloxane.

In the invention, the cyclomethicone can be dodecamethylcyclohexasiloxane, the aminosiloxane can be 3- (2-aminoethylamino) propyltrimethoxysilane, and the polymethylphenylsiloxane can be phenyl trimethicone, also called as polyphenyl methylsilicone.

In a preferred embodiment, the mass ratio of the modified activated carbon II to the siloxane is 1: 0.001-0.3, preferably 1: 0.005-0.01.

In a preferred embodiment, the treatment temperature of the third heat treatment is 370-450 ℃, preferably 390-410 ℃, and the heating time is 1-3h, preferably 1.5-2.5 h.

Wherein, through the third heat treatment, siloxane can form a layer of siloxane film on the surface of the active carbon, thereby playing the role of modifying the active carbon.

In a second aspect, the present invention provides a modified activated carbon prepared by the modification method of the first aspect of the present invention.

In a preferred embodiment, the surface of the modified activated carbon is sequentially covered with a polyimide film layer and a siloxane film layer from inside to outside, wherein the mass ratio of the activated carbon to the polyimide film layer to the siloxane film layer is 1: 0.01-1.2: 0.001-0.03, preferably 1: 0.2-0.4: 0.005-0.02.

In a preferred embodiment, the specific surface area of the modified activated carbon is 1850-³(ii)/g, preferably 1880-2120m³/g。

In a preferred embodiment, the modified activated carbon has the adsorption capacity of carbon dioxide of 3.6-3.9mmol/g, the wear-resistant strength of more than or equal to 98% and the water-resistant strength of 3-3.7 MPa.

In a further preferable embodiment, the adsorption capacity of the modified activated carbon to carbon dioxide is 3.7-3.8mmol/g, the abrasion resistance is more than or equal to 98.5%, and the water resistance strength is 3.4-3.6 MPa.

The present invention will be described in detail below by way of examples. The coconut shell activated carbon in the examples and the comparative examples is purchased from a Beishan mountain Daqing activated carbon factory of Jiangyi city, the particle size of the coconut shell activated carbon is 3mm, the iodine value is more than or equal to 950mg/L, the hardness is more than or equal to 92 percent, and the ash content is 5-8 percent. Polyethyleneimine was purchased from Sigma-Aldrich under the cat # 904759-100G. The polyetherimide was purchased from Sigma-Aldrich under the designation 700193-250G. Polydimethylsiloxane was purchased from Sigma-Aldrich under the designation DMPSV-500G.

Example 1

Under the protection of nitrogen, the nitrogen is used for protecting the air,

1) placing coconut shell activated carbon in a closed rotary furnace, treating for 2 hours at 650 ℃, and then cooling to room temperature to obtain modified activated carbon I;

2) mixing 10g of modified activated carbon I and 3g of polyethyleneimine, placing the mixture in a closed rotary furnace, treating the mixture at 170 ℃ for 1.5h, and then cooling the mixture to room temperature to obtain modified activated carbon II;

3) and mixing 10g of modified activated carbon II and 0.05g of polydimethylsiloxane, placing the mixture in a closed rotary furnace, treating the mixture at 400 ℃ for 1h, and then cooling the mixture to room temperature to obtain the modified activated carbon.

Example 2

Under the protection of nitrogen, the nitrogen is used for protecting the air,

1) placing coconut shell activated carbon in a closed rotary furnace, treating for 1.5h at 700 ℃, and then cooling to room temperature to obtain modified activated carbon I;

2) mixing 10g of modified activated carbon I and 3g of polyethyleneimine, placing the mixture in a closed rotary furnace, treating the mixture at 180 ℃ for 1.5h, and then cooling the mixture to room temperature to obtain modified activated carbon II;

3) and mixing 10g of modified activated carbon II and 0.07g of polydimethylsiloxane, placing the mixture in a closed rotary furnace, treating the mixture at 390 ℃ for 2.5h, and then cooling the mixture to room temperature to obtain the modified activated carbon.

Example 3

Under the protection of nitrogen, the nitrogen is used for protecting the air,

1) placing coconut shell activated carbon in a closed rotary furnace, treating for 2.5h at 600 ℃, and then cooling to room temperature to obtain modified activated carbon I;

2) mixing 10g of modified activated carbon I and 3g of polyethyleneimine, placing the mixture in a closed rotary furnace, treating the mixture at 160 ℃ for 2 hours, and then cooling the mixture to room temperature to obtain modified activated carbon II;

3) and mixing 10g of modified activated carbon II and 0.1g of polydimethylsiloxane, placing the mixture in a closed rotary furnace, treating the mixture at 410 ℃ for 1.5h, and then cooling the mixture to room temperature to obtain the modified activated carbon.

Example 4

Under the protection of nitrogen, the nitrogen is used for protecting the air,

1) placing coconut shell activated carbon in a closed rotary furnace, treating for 3h at 550 ℃, and then cooling to room temperature to obtain modified activated carbon I;

2) mixing 10g of modified activated carbon I and 2g of polyetherimide, placing the mixture in a closed rotary furnace, treating the mixture at 200 ℃ for 1 hour, and then cooling the mixture to room temperature to obtain modified activated carbon II;

3) 10g of modified activated carbon II and 0.1g of 3- (2-aminoethylamino) propyl trimethoxy silane are mixed and then placed in a closed rotary furnace, the mixture is treated at 450 ℃ for 1h, and then the temperature is reduced to room temperature, so that the modified activated carbon is obtained.

Comparative example 1

Similar to the modification method of example 1 except that step (2) is omitted.

Comparative example 2

Similar to the modification method of example 1 except that step (3) is omitted.

Test example 1

The coconut shell activated carbon, the modified activated carbons prepared in examples 1 to 4 and comparative examples 1 to 2 were tested for specific surface area and adsorption amount of carbon dioxide gas having a purity of 99.9% by using a fully automatic specific surface area and porosity analyzer ASAP 2060 of mack corporation, and the test results are shown in table 1.

Test example 2

The coconut shell activated carbon, the modified activated carbon prepared in examples 1 to 4 and comparative examples 1 to 2 were subjected to the abrasion resistance test according to the test method for coal-based granular activated carbon for desulfurization and denitrification part 3, abrasion resistance and compressive strength GB/T30202.3-2013, and the test results are shown in Table 1.

Test example 3

After the coconut shell activated carbon before modification, the modified activated carbons prepared in examples 1-4 and comparative examples 1-2 were soaked in water for 60 days, the water resistance strength test was performed according to the strength test method of GB T20451-.

TABLE 1

As can be seen from table 1, the modified activated carbon prepared in comparative example 1 is good in water resistance and abrasion resistance, but poor in adsorption capacity to carbon dioxide; the modified activated carbon prepared in comparative example 2 was poor in water and abrasion resistance, but good in carbon dioxide adsorption capacity. The modified activated carbon prepared in the embodiments 1 to 4 has large carbon dioxide adsorption capacity, high wear resistance and good water resistance, and the comprehensive performance of the modified activated carbon is obviously improved.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.