Preparation process of modified activated carbon

Abstract

The invention discloses a preparation process of modified activated carbon, which comprises the following steps: (1) firstly putting activated carbon into an enhanced activation solution, stirring, filtering, and then carrying out constant-temperature heat treatment to obtain primarily modified activated carbon; and (2) mixing the preliminarily modified activated carbon with a silane coupling agent solution, performing ultrasonic dispersion treatment, performing heating reflux treatment, filtering, and performing segmented heat treatment to obtain the modified activated carbon. According to the preparation process disclosed by the invention, the modified activated carbon has excellent wear resistance and water resistance, and the adsorption capacity of the modified activated carbon to carbon dioxide is also improved.

Description

Technical Field

[0001] The present invention relates to a preparation process of modified activated carbon, belonging to the technical field of activated carbon modification. Background Art

[0002] Activated carbon is a porous black solid carbonaceous material with strong adsorption capacity, which can be used for air or water purification and is a commonly used adsorption material.

[0003] The adsorption performance of unmodified activated carbon mainly depends on physical adsorption, with relatively low adsorption capacity and selectivity, and low strength, being prone to pulverization, having problems of poor abrasion resistance and water resistance; modifying activated carbon through preparation processes such as surface oxidation modification, surface reduction modification, and metal loading modification will improve the adsorption capacity, adsorption selectivity or pertinence of activated carbon, but the improvement degree of the abrasion resistance and water resistance performance of activated carbon is relatively small. Summary of the Invention

[0004] At least aiming at one of the above problems existing in the prior art, the present invention provides a preparation process of modified activated carbon, which can make the modified activated carbon have excellent abrasion resistance and water resistance, while taking into account the improvement of the adsorption capacity for pollutants such as carbon dioxide, VOCs, metal ions, and organic substances.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: A preparation process of modified activated carbon, comprising the following steps:

[0006] (1) First, place the activated carbon in an enhanced activation solution, stir, filter, and then perform constant temperature heat treatment to obtain preliminarily modified activated carbon;

[0007] (2) Then, mix the preliminarily modified activated carbon with a silane coupling agent solution, perform ultrasonic dispersion treatment, then heat reflux treatment, filter, and then perform segmented heat treatment to obtain modified activated carbon.

[0008] Preferably, for the stirring treatment: the temperature is 20 - 25 °C, the stirring rate is 200 - 250 rpm, and the time is 20 - 28 h.

[0009] Preferably, for the constant temperature heat treatment: in an inert atmosphere, the temperature is 620 - 660 °C, and the time is 60 - 90 min.

[0010] Preferably, the enhanced activation solution uses water as the solvent and diammonium hydrogen phosphate and potassium hydroxide as the enhanced activation agents.

[0011] Preferably, in the enhanced activation solution, the content of diammonium hydrogen phosphate is 25 - 32 wt%, and the content of potassium hydroxide is 8 - 12 wt%.

[0012] Preferably, the mass ratio of the enhanced activation solution to the activated carbon is 4.5 - 5.6:1.

[0013] Preferably, for ultrasonic dispersion treatment: the power is 1500 - 1800 W and the time is 5 - 10 min.

[0014] Preferably, for heating reflux treatment: the time is 2 - 3 h.

[0015] Preferably, for segmented heat treatment: under an inert atmosphere, first preliminarily heat up to 75 - 85 °C and hold for 60 - 90 min, then heat up at the same rate to 185 - 195 °C and hold for 120 - 150 min, and finally accelerate the heating to 530 - 570 °C and hold for 120 - 150 min.

[0016] Preferably, the rate of preliminary heating and heating at the same rate is 10 - 15 °C / min, and the rate of accelerated heating is 30 - 40 °C / min.

[0017] Preferably, the silane coupling agent solution uses ethanol as the solvent and amino silane and epoxy silane as the coupling agents.

[0018] Preferably, in the silane coupling agent solution, the mass ratio of the silane coupling agent to ethanol is 1:6 - 8, and the mass ratio of amino silane to epoxy silane is 3 - 4:1.5.

[0019] Preferably, the mass ratio of the silane coupling agent solution to the activated carbon is 3.5 - 4.5:1.

[0020] Preferably, the amino silane coupling agent is γ-aminopropyltriethoxysilane (KH-550), N-phenyl-γ-aminopropyltrimethoxysilane, etc.

[0021] Preferably, the epoxy silane coupling agent is γ-glycidoxypropyltrimethoxysilane (KH-560), γ-(2,3-epoxypropoxy)propyltriethoxysilane.

[0022] Advantages of the present invention: The preparation process of the modified activated carbon of the present invention uses an enhanced activator and a silane coupling agent for modification and combines post-treatment, effectively improving the wear resistance and water resistance of the modified activated carbon and increasing the adsorption capacity for carbon dioxide and formaldehyde; the preparation process of the modified activated carbon of the present invention has a simple process and convenient operation; the preparation process of the modified activated carbon of the present invention uses diammonium hydrogen phosphate and potassium hydroxide in combination as the enhanced activator, and the two work synergistically to simultaneously increase the adsorption capacity and strength of the modified activated carbon; the preparation process of the modified activated carbon of the present invention uses an amino silane coupling agent and an epoxy silane coupling agent in combination, and the two work synergistically to simultaneously increase the wear resistance and water resistance of the modified activated carbon; the preparation process of the modified activated carbon of the present invention. Detailed implementation manners

[0023] The following is a clear and complete description of the technical solutions in the implementation of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer.

[0024] Example 1

[0025] A preparation process of modified activated carbon is as follows:

[0026] (1) First, place 15 g of coconut shell activated carbon in 75 g of enhanced activation solution, stir at a temperature of 20 - 25 °C and a rate of 200 rpm for 28 h, filter, and then perform isothermal heat treatment at 620 °C in a nitrogen atmosphere for 90 min to obtain preliminarily modified activated carbon;

[0027] Among them, the enhanced activation solution is prepared from water, diammonium hydrogen phosphate, and potassium hydroxide, and the content of diammonium hydrogen phosphate is 28 wt%, and the content of potassium hydroxide is 10 wt%;

[0028] (2) Then mix the above-mentioned preliminarily modified activated carbon with 53 g of silane coupling agent solution, perform ultrasonic dispersion treatment at a power of 1500 W for 10 min, then perform heating reflux treatment for 3 h, filter, and then perform segmented heat treatment: in a nitrogen atmosphere, first heat up to 75 °C at a rate of 10 °C / min, hold for 90 min, then heat up to 185 °C at a rate of 10 °C / min, hold for 120 min, and finally heat up to 530 °C at a rate of 30 °C / min, hold for 150 min to obtain modified activated carbon;

[0029] Among them, the silane coupling agent solution is prepared from ethanol, KH-550, and KH-560, and the mass ratio of KH-550 to KH-560 is 3:1.5, and the mass ratio of the sum of the masses of KH-550 and KH-560 to ethanol is 1:6.

[0030] Example 2

[0031] A preparation process of modified activated carbon is as follows:

[0032] (1) First, place 15 g of coconut shell activated carbon in 84 g of enhanced activation solution, stir at a temperature of 20 - 25 °C and a rate of 220 rpm for 24 h, filter, and then perform isothermal heat treatment at 640 °C in a nitrogen atmosphere for 75 min to obtain preliminarily modified activated carbon;

[0033] Among them, the enhanced activation solution is prepared from water, diammonium hydrogen phosphate, and potassium hydroxide, with the content of diammonium hydrogen phosphate being 25 wt% and the content of potassium hydroxide being 8 wt%.

[0034] (2) Then mix the above-mentioned preliminarily modified activated carbon with 67 g of the silane coupling agent solution, perform ultrasonic dispersion treatment at a power of 1600 W for 8 min, then perform heating reflux treatment for 2.5 h, filter, and then perform segmented heat treatment: under a nitrogen atmosphere, first heat up to 80 °C at a rate of 12 °C / min, hold for 75 min, then heat up to 180 °C at a rate of 12 °C / min, hold for 135 min, and finally heat up to 550 °C at a rate of 35 °C / min, hold for 135 min to obtain modified activated carbon.

[0035] Among them, the silane coupling agent solution is prepared from ethanol, KH-550, and KH-560, and the mass ratio of KH-550 to KH-560 is 3.5:1.5, and the mass ratio of the sum of the masses of KH-550 and KH-560 to ethanol is 1:7.

[0036] Example 3

[0037] A preparation process of modified activated carbon, and the specific process steps are as follows:

[0038] (1) First, place 15 g of coconut shell activated carbon in 68 g of the enhanced activation solution, perform stirring treatment at a temperature of 20 - 25 °C and a rate of 250 rpm for 20 h, filter, and then perform constant temperature heat treatment at a nitrogen atmosphere and a temperature of 660 °C for 60 min to obtain preliminarily modified activated carbon.

[0039] Among them, the enhanced activation solution is prepared from water, diammonium hydrogen phosphate, and potassium hydroxide, with the content of diammonium hydrogen phosphate being 32 wt% and the content of potassium hydroxide being 12 wt%.

[0040] (2) Then mix the above-mentioned preliminarily modified activated carbon with 60 g of the silane coupling agent solution, perform ultrasonic dispersion treatment at a power of 1800 W for 5 min, then perform heating reflux treatment for 2 h, filter, and then perform segmented heat treatment: under a nitrogen atmosphere, first heat up to 85 °C at a rate of 15 °C / min, hold for 60 min, then heat up to 195 °C at a rate of 15 °C / min, hold for 120 min, and finally heat up to 530 °C at a rate of 40 °C / min, hold for 120 min to obtain modified activated carbon.

[0041] Among them, the silane coupling agent solution is prepared from ethanol, KH-550, and KH-560, and the mass ratio of KH-550 to KH-560 is 4:1.5, and the mass ratio of the sum of the masses of KH-550 and KH-560 to ethanol is 1:8.

[0042] Comparative Example 1

[0043] A preparation process of modified activated carbon, different from Example 1: (1) First, 15 g of activated carbon is subjected to isothermal heat treatment at 620 °C in a nitrogen atmosphere for 90 min to obtain preliminarily modified activated carbon.

[0044] Comparative Example 2

[0045] A preparation process of modified activated carbon, different from Example 1: First, 15 g of activated carbon is placed in 75 g of enhanced activation solution, stirred at a temperature of 20 - 25 °C and a rate of 200 rpm for 28 h, filtered, and dried in a nitrogen atmosphere at 60 °C for 150 min to obtain preliminarily modified activated carbon.

[0046] Comparative Example 3

[0047] A preparation process of modified activated carbon, different from Example 1: The enhanced activation solution used is composed of water and diammonium hydrogen phosphate, with the content of diammonium hydrogen phosphate being 25 wt%.

[0048] Comparative Example 4

[0049] A preparation process of modified activated carbon, different from Example 1: (2) Then, the above-mentioned preliminarily modified activated carbon and 53 g of silane coupling agent solution are mixed, ultrasonically dispersed at a power of 1500 W for 10 min, then filtered, and then subjected to segmented heat treatment: in a nitrogen atmosphere, first heated to 75 °C at a rate of 10 °C / min, held for 90 min, then heated to 185 °C at a rate of 10 °C / min, held for 120 min, and finally heated to 530 °C at a rate of 30 °C / min, held for 150 min to obtain modified activated carbon.

[0050] Comparative Example 5

[0051] A preparation process of modified activated carbon, different from Example 1: (2) Then, the above-mentioned preliminarily modified activated carbon and 53 g of silane coupling agent solution are mixed, ultrasonically dispersed at a power of 1500 W for 10 min, then subjected to heat reflux treatment for 3 h, filtered, and then subjected to isothermal heat treatment: in a nitrogen atmosphere at 530 °C for 240 min.

[0052] Comparative Example 6

[0053] A preparation process of modified activated carbon, different from Example 1: (2) Then, the above-mentioned preliminarily modified activated carbon and 53 g of silane coupling agent solution are mixed, ultrasonically dispersed at a power of 1500 W for 10 min, then subjected to heat reflux treatment for 3 h, filtered, and then subjected to segmented heat treatment: in a nitrogen atmosphere, first treated at 75 °C for 90 min, and then treated at 530 °C for 210 min.

[0054] Comparative Example 7

[0055] A preparation process of modified activated carbon, different from Example 1: The silane coupling agent solution used is prepared from ethanol and KH-550, and the mass ratio of the sum of the masses of KH-550 to ethanol is 1:6.

[0056] Comparative Example 8

[0057] A preparation process of modified activated carbon, different from Example 1: The silane coupling agent solution used is prepared from ethanol and KH-560, and the mass ratio of the sum of the masses of KH-560 to ethanol is 1:6.

[0058] The modified activated carbons prepared in Examples 1 to 3 and Comparative Examples 1 to 8 were tested, and coconut shell activated carbon was used as the control group; the results are shown in the following table of product performance.

[0059] 1. The abrasion resistance was measured with reference to GB / T30202.3-2013.

[0060] 2. After the modified activated carbon was soaked in water for 90 days, the water resistance strength was measured with reference to GB / T20451-2016.

[0061] 3. The specific surface area was measured using a fully automatic specific surface area and porosity analyzer, and the adsorption capacities for carbon dioxide gas and VOCs were measured at a temperature of 30°C and a humidity of 90%.

[0062] Product performance

[0063]

[0064] As can be seen from the above table, through the preparation process of the present invention, the modified activated carbons prepared in Examples 1 to 3 have higher abrasion resistance and water resistance strengths, and the adsorption capacities for carbon dioxide and formaldehyde are improved.

[0065] In summary, the preparation process of the present invention uses an enhanced activator and a silane coupling agent for modification, combined with subsequent heat treatment, so that the abrasion resistance and water resistance of the modified activated carbon are effectively improved, and the adsorption capacities for carbon dioxide, formaldehyde, metals, etc. are also improved.

[0066] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit and basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

[0067] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A preparation process of modified activated carbon, characterized in that, It includes the following steps: (1) First, place the activated carbon in the enhanced activation solution, stir, filter, and then perform constant-temperature heat treatment to obtain preliminarily modified activated carbon; (2) Then, mix the preliminarily modified activated carbon with the silane coupling agent solution, perform ultrasonic dispersion treatment, then perform heating reflux treatment, filter, and then perform segmented heat treatment to obtain modified activated carbon.

2. The preparation process of a modified activated carbon according to claim 1, characterized in that, The constant-temperature heat treatment: Under an inert atmosphere, the temperature is 620 - 660 °C, and the time is 60 - 90 min.

3. The preparation process of a modified activated carbon according to claim 1, characterized in that, The segmented heat treatment: Under an inert atmosphere, first preliminarily raise the temperature to 75 - 85 °C, hold for 60 - 90 min, then raise the temperature at the same speed to 185 - 195 °C, hold for 120 - 150 min, and finally accelerate the temperature rise to 530 - 570 °C, hold for 120 - 150 min.

4. The preparation process of a modified activated carbon according to claim 3, characterized in that, The rate of preliminary temperature rise and temperature rise at the same speed is 10 - 15 °C / min; the rate of accelerated temperature rise is 30 - 40 °C / min.

5. The preparation process of a modified activated carbon according to claim 1, characterized in that, The heating reflux treatment: The time is 2 - 3 h.

6. The preparation process of a modified activated carbon according to claim 1, characterized in that, The stirring treatment: The temperature is 20 - 25 °C, the stirring rate is 200 - 250 rpm, and the time is 20 - 28 h.

7. The preparation process of a modified activated carbon according to claim 1, characterized in that, The enhanced activation solution uses water as the solvent and diammonium hydrogen phosphate and potassium hydroxide as the enhanced activators; the silane coupling agent solution uses ethanol as the solvent and amino silane and epoxy silane as the coupling agents.

8. The preparation process of a modified activated carbon according to claim 1 or 7, characterized in that, In the enhanced activation solution, the content of diammonium hydrogen phosphate is 25 - 32 wt%, and the content of potassium hydroxide is 8 - 12 wt%; in the silane coupling agent solution, the mass ratio of the silane coupling agent to ethanol is 1:6 - 8, and the mass ratio of amino silane to epoxy silane is 3 - 4:1.

5.

9. The preparation process of a modified activated carbon according to claim 8, characterized in that, The amino silane coupling agent is one of γ-aminopropyltriethoxysilane or N-phenyl-γ-aminopropyltrimethoxysilane; the epoxy silane coupling agent is one of γ-glycidoxypropyltrimethoxysilane or γ-(2,3-epoxypropoxy)propyltriethoxysilane.

10. The preparation process of a modified activated carbon according to claim 1, characterized in that, The mass ratio of the enhanced activation solution to the activated carbon is 4.5 - 5.6:1; the mass ratio of the silane coupling agent solution to the activated carbon is 3.5 - 4.5:1.

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