Preparation process of modified activated carbon

Abstract

The application discloses a preparation process of modified activated carbon, which comprises the following steps: (1) first, the activated carbon is placed in an enhanced activation solution, stirred, filtered, and then subjected to constant temperature heat treatment to obtain preliminary modified activated carbon; (2) then, the preliminary modified activated carbon is mixed with a silane coupling agent solution, subjected to ultrasonic dispersion treatment, and then subjected to heating reflux treatment, filtration and segmented heat treatment to obtain modified activated carbon. The preparation process makes the modified activated carbon have excellent wear resistance and water resistance, and also improves the carbon dioxide adsorption capacity of the modified activated carbon.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation process of modified activated carbon, and belongs to the technical field of activated carbon modification. BACKGROUND

[0002] Activated carbon is a kind of porous black solid carbon, which has strong adsorption capacity and can purify air or water, and is a commonly used adsorbent.

[0003] The adsorption performance of unmodified activated carbon mainly depends on physical adsorption, and the adsorption capacity and selectivity are relatively low, and the strength is low, which is easy to pulverize, and has the problems of poor wear resistance and water resistance. After surface oxidation modification, surface reduction modification, and metal loading modification, the adsorption capacity, adsorption selectivity, or specificity of the modified activated carbon are improved, but the wear resistance and water resistance of the activated carbon are less improved. SUMMARY

[0004] At least for one problem of the prior art, the present application provides a preparation process of modified activated carbon, which can make the modified activated carbon have excellent wear resistance and water resistance, and at the same time improve the adsorption capacity of carbon dioxide, VOCs, metal ions, and organic pollutants.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: a preparation process of modified activated carbon, comprising the following steps:

[0006] (1) first, the activated carbon is placed in an enhanced activation solution, stirred, filtered, and then subjected to constant temperature heat treatment to obtain a preliminary modified activated carbon;

[0007] (2) then, the preliminary modified activated carbon is mixed with a silane coupling agent solution, subjected to ultrasonic dispersion treatment, and then subjected to heating reflux treatment, filtration, and then subjected to stepwise heat treatment to obtain a modified activated carbon.

[0008] Preferably, the stirring treatment is carried out at a temperature of 20-25℃, a stirring rate of 200-250rpm, and a time of 20-28h.

[0009] Preferably, the constant temperature heat treatment is carried out at a temperature of 620-660℃ under an inert atmosphere for 60-90min.

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

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

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

[0013] Preferably, the ultrasonic dispersion treatment is performed at a power of 1500-1800 W for 5-10 min.

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

[0015] Preferably, the stepwise heat treatment is performed as follows: first, the temperature is preliminarily raised to 75-85 DEG C under an inert atmosphere, and maintained for 60-90 min; then, the temperature is raised to 185-195 DEG C at the same speed, and maintained for 120-150 min; finally, the temperature is accelerated to 530-570 DEG C, and maintained for 120-150 min.

[0016] Preferably, the preliminary temperature raising and the temperature raising at the same speed are performed at a speed of 10-15 DEG C / min, and the accelerated temperature raising is performed at a speed of 30-40 DEG C / min.

[0017] Preferably, the silane coupling agent solution uses ethanol as the solvent, and uses aminosilane and epoxysilane 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 aminosilane to epoxysilane 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 aminosilane coupling agent is gamma-aminopropyl triethoxysilane (KH-550), N-phenyl-gamma-aminopropyl trimethoxysilane, etc.

[0021] Preferably, the epoxysilane coupling agent is gamma-glycidoxypropyl trimethoxysilane (KH-560), gamma-(2,3-epoxypropoxy) propyl triethoxysilane.

[0022] The present application has the following advantages: the preparation process of the modified activated carbon of the present application uses an enhanced activation agent and a silane coupling agent for modification, and combines post-treatment, so that the wear resistance and water resistance of the modified activated carbon are effectively improved, and the adsorption capacity for carbon dioxide and formaldehyde is improved; the preparation process of the modified activated carbon of the present application is simple and easy to operate; the preparation process of the modified activated carbon of the present application uses diammonium hydrogen phosphate and potassium hydroxide in combination as the enhanced activation agent, and the two agents are synergistic, so that the adsorption capacity and strength of the modified activated carbon are simultaneously improved; the preparation process of the modified activated carbon of the present application uses aminosilane coupling agents and epoxysilane coupling agents in combination, and the two agents are synergistic, so that the wear resistance and water resistance of the modified activated carbon are simultaneously improved; and the preparation process of the modified activated carbon of the present application. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solutions in the embodiments of the present application. The described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. If specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used.

[0024] Embodiment 1

[0025] A preparation process of modified activated carbon, the specific process steps are as follows:

[0026] (1) First, 15 g of coconut shell activated carbon is placed in 75 g of enhanced activation solution, stirred at a temperature of 20-25℃ and a rate of 200 rpm for 28 h, filtered, and then subjected to constant temperature heat treatment at a temperature of 620℃ under a nitrogen atmosphere for 90 min to obtain a preliminary modified activated carbon;

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

[0028] (2) Then, the preliminary modified activated carbon and 53 g of silane coupling agent solution are mixed, ultrasonically dispersed at a power of 1500W for 10 min, and then heated and refluxed for 3 h, filtered, and then subjected to stepwise heat treatment: first, heated to 75℃ at a rate of 10℃ / min under a nitrogen atmosphere, kept for 90 min, then heated to 185℃ at a rate of 10℃ / min, kept for 120 min, and finally heated to 530℃ at a rate of 30℃ / min, kept for 150 min, to obtain a modified activated carbon;

[0029] 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 mass of KH-550 and KH-560 to the mass of ethanol is 1:6.

[0030] Embodiment 2

[0031] A preparation process of modified activated carbon, the specific process steps are as follows:

[0032] (1) First, 15 g of coconut shell activated carbon is placed in 75 g of enhanced activation solution, stirred at a temperature of 20-25℃ and a rate of 200 rpm for 28 h, filtered, and then subjected to constant temperature heat treatment at a temperature of 620℃ under a nitrogen atmosphere for 90 min to obtain a preliminary modified activated carbon;

[0033] The enhanced activation solution is prepared from water, diammonium hydrogen phosphate and potassium hydroxide, and the content of diammonium hydrogen phosphate is 25wt%, and the content of potassium hydroxide is 8wt%;

[0034] (2) The preliminary modified activated carbon is mixed with 67g of the silane coupling agent solution, and is subjected to ultrasonic dispersion treatment at a power of 1600W for 8min, and is then subjected to heating reflux treatment for 2.5h, and is filtered, and is then subjected to staged heat treatment: under a nitrogen atmosphere, first, the temperature is increased to 80℃ at a rate of 12℃ / min, and is maintained for 75min, then the temperature is increased to 180℃ at a rate of 12℃ / min, and is maintained for 135min, and finally, the temperature is increased to 550℃ at a rate of 35℃ / min, and is maintained for 135min, to obtain the modified activated carbon;

[0035] 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 mass of KH-550 and the mass of KH-560 to the mass of ethanol is 1:7.

[0036] Example 3

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

[0038] (1) First, 15 coconut shell activated carbons are placed in 68g of an enhanced activation solution, and are subjected to stirring treatment at a temperature of 20-25℃ and a rate of 250rpm for 20h, and are filtered, and are then subjected to constant temperature heat treatment under a nitrogen atmosphere at a temperature of 660℃ for 60min, to obtain a preliminary modified activated carbon;

[0039] The enhanced activation solution is prepared from water, diammonium hydrogen phosphate and potassium hydroxide, and the content of diammonium hydrogen phosphate is 32wt%, and the content of potassium hydroxide is 12wt%;

[0040] (2) The preliminary modified activated carbon is mixed with 60g of the silane coupling agent solution, and is subjected to ultrasonic dispersion treatment at a power of 1800W for 5min, and is then subjected to heating reflux treatment for 2h, and is filtered, and is then subjected to staged heat treatment: under a nitrogen atmosphere, first, the temperature is increased to 85℃ at a rate of 15℃ / min, and is maintained for 60min, then the temperature is increased to 195℃ at a rate of 15℃ / min, and is maintained for 120min, and finally, the temperature is increased to 530℃ at a rate of 40℃ / min, and is maintained for 120min, to obtain the modified activated carbon;

[0041] 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 mass of KH-550 and the mass of KH-560 to the mass of ethanol is 1:8.

[0042] Comparative Example 1

[0043] A preparation process of modified activated carbon, which is different from example 1: (1) first heat treat 15g activated carbon under nitrogen atmosphere at 620℃ for 90min to obtain preliminary modified activated carbon.

[0044] Comparative example 2

[0045] A preparation process of modified activated carbon, which is different from example 1: first put 15g activated carbon into 75g enhanced activation solution, stir at 20-25℃ and 200rpm for 28h, filter, and dry at 60℃ under nitrogen atmosphere for 150min to obtain preliminary modified activated carbon.

[0046] Comparative example 3

[0047] A preparation process of modified activated carbon, which is different from example 1: the enhanced activation solution used is prepared from water and diammonium hydrogen phosphate, and the content of diammonium hydrogen phosphate is 25wt%.

[0048] Comparative example 4

[0049] A preparation process of modified activated carbon, which is different from example 1: (2) mix the preliminary modified activated carbon above with 53g silane coupling agent solution, ultrasonic dispersion treatment at 1500W for 10min, then filter, and then perform stepwise heat treatment: first heat to 75℃ at 10℃ / min under nitrogen atmosphere, keep for 90min, then heat to 185℃ at 10℃ / min, keep for 120min, and finally heat to 530℃ at 30℃ / min, keep for 150min to obtain modified activated carbon.

[0050] Comparative example 5

[0051] A preparation process of modified activated carbon, which is different from example 1: (2) mix the preliminary modified activated carbon above with 53g silane coupling agent solution, ultrasonic dispersion treatment at 1500W for 10min, then heat reflux treatment for 3h, filter, and then perform constant temperature heat treatment: 240min at 530℃ under nitrogen atmosphere.

[0052] Comparative example 6

[0053] A preparation process of modified activated carbon, which is different from example 1: (2) mix the preliminary modified activated carbon above with 53g silane coupling agent solution, ultrasonic dispersion treatment at 1500W for 10min, then heat reflux treatment for 3h, filter, and then perform stepwise heat treatment: first heat at 75℃ for 90min under nitrogen atmosphere, and then heat at 530℃ for 210min.

[0054] Comparative example 7

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

[0056] Comparative example 8

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

[0058] The modified activated carbon prepared in example 1 to example 3 and comparative example 1 to comparative example 8 is tested, and coconut shell activated carbon is used as a control group; the results are shown in the following table of product performance.

[0059] 1. The abrasion resistance is determined according to GB / T30202.3-2013.

[0060] 2. After the modified activated carbon is soaked in water for 90 days, the water resistance is determined according to GB / T20451-2016.

[0061] 3. The specific surface area is determined by using a full-automatic specific surface and porosity analyzer, and the adsorption capacity of carbon dioxide gas and VOCs at a temperature of 30℃ and a humidity of 90%.

[0062] Product performance

[0063]

[0064] As shown in the above table, by the preparation process of the present application, the modified activated carbon prepared in example 1 to example 3 has higher abrasion resistance and water resistance, and the adsorption capacity of carbon dioxide and formaldehyde is improved.

[0065] In summary, by the preparation process of the present application, the activated carbon is modified by using an enhanced activator and a silane coupling agent, and the subsequent heat treatment is used to effectively improve the abrasion resistance and water resistance of the modified activated carbon, and the adsorption capacity of carbon dioxide, formaldehyde and metal is also improved.

[0066] It is apparent for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit and essential characteristics of the present application. Therefore, the embodiments should be considered in all aspects as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

[0067] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes every feature described. The specification can include implicit combinations of explicitly mentioned features and / or explicit combinations of implicitely mentioned features. Each embodiment depends on the explicit combinations of features and / or the implicit combinations of features made specifically within that embodiment, and each such embodiment can be combined with every other such embodiment to create further embodiments.

Claims

1. A process for the preparation of a modified activated carbon, characterized in that, It comprises the following steps: (1) first, the activated carbon is placed in the enhanced activation solution, stirred, filtered, and then subjected to constant temperature heat treatment to obtain preliminary modified activated carbon; (2) then, the preliminary modified activated carbon is mixed with a silane coupling agent solution, subjected to ultrasonic dispersion treatment, and then heated to reflux, filtered, and then subjected to segmented heat treatment to obtain modified activated carbon; The segmented heat treatment is as follows: under an inert atmosphere, first, the temperature is preliminarily increased to 75-85℃, maintained for 60-90min, then increased to 185-195℃ at the same speed, maintained for 120-150min, and finally accelerated to 530-570℃, maintained for 120-150min; The enhanced activation solution uses water as the solvent and diammonium hydrogen phosphate and potassium hydroxide as the enhanced activation agent; the silane coupling agent solution uses ethanol as the solvent and amino silane and epoxy silane as the coupling agent; In the enhanced activation solution, the content of diammonium hydrogen phosphate is 25-32wt%, and the content of potassium hydroxide is 8-12wt%; in the silane coupling agent solution, the mass ratio of silane coupling agent to ethanol is 1:6-8, and the mass ratio of amino silane to epoxy silane is 3-4:1.

5.

2. The process for preparing a modified activated carbon according to claim 1, characterized in that, The constant temperature heat treatment is as follows: under an inert atmosphere, the temperature is 620-660℃, and the time is 60-90min.

3. The process for preparing a modified activated carbon according to claim 1, characterized in that, The preliminary temperature increase and the constant speed temperature increase rate are 10-15℃ / min; The accelerated temperature increase is 30-40℃ / min.

4. The process for preparing a modified activated carbon according to claim 1, characterized in that, The heating reflux treatment time is 2-3h.

5. The process for preparing a modified activated carbon according to claim 1, characterized in that, The stirring treatment temperature is 20-25℃, the stirring rate is 200-250rpm, and the time is 20-28h.

6. The process for preparing a modified activated carbon according to claim 1, characterized in that, The amino silane is one of γ-aminopropyl triethoxysilane or N-phenyl-γ-aminopropyl trimethoxysilane; the epoxy silane is one of γ-glycidyl ether propyl trimethoxysilane or γ-(2,3-epoxypropoxy) propyl triethoxysilane.

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

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