KR20130118007A - Process for preparing carbon dioxide adsorbent by amine enrichment - Google Patents

Abstract

PURPOSE: A manufacturing method for a carbon dioxide adhesive using an amine concentration method is provided to manufacture a carbon dioxide adhesive having high capturing ability and excellent selectivity within a short time without the consumption of excessive energy. CONSTITUTION: A manufacturing method for a carbon dioxide adhesive having a nitrogen functional group comprises: a step which mixes and stirs activated charcoal and amine solutions; and a step which concentrates the mixed solution with reduced pressure by a rotary evaporator. The specific surface area of the activated charcoal is 1200-1500 m/g. And the particle size of the activated charcoal is 5-10 mm.

Description

Process for Preparing Carbon Dioxide Adsorbent by Amine Enrichment

The present invention relates to a method for producing a carbon dioxide adsorbent using amine concentration. More specifically, the present invention relates to a method for producing a carbon dioxide adsorbent having excellent selective capturing ability to carbon dioxide simply and efficiently by using an amine concentration method.

Since carbon dioxide deteriorates the quality of indoor air and is a major culprit of global warming, there is an urgent need to develop a technology that can control the concentration of carbon dioxide.

Activated carbon (AC) has a large specific surface area, which has a large adsorption capacity for gas molecules including odors, and developed micropores are exposed to the surface of pores, so adsorption speed is high. Removal ability is high. In addition, unlike zeolite, a well-known carbon dioxide absorbent, it has a relatively low effect on moisture and is widely used at a low price. However, since the capturing ability of carbon dioxide, which is a greenhouse gas and one of indoor air pollutants, is very low, efforts have been made to overcome it through various surface modifications.

Specifically, research and development such as reforming by an acid-base reaction or forming an alkali functional group through amine or ammonia surface treatment are underway. However, most of the techniques use wet ion exchange or impregnation methods, which require very long manufacturing times, require secondary treatment of contaminants generated during washing after impregnation, and the uneven distribution of nitrogen functional groups formed on the adsorbent surface. There is a problem that is difficult to maximize the selective collection effect of.

On the other hand, while the dry method shows a good removal rate of carbon dioxide, it requires a relatively high energy consumption because most of the heat should be applied to 200 to 800 ℃.

The present inventors have diligently studied to overcome the problems of the conventional dry method, wet ion exchange or impregnation method as described above. The present invention was completed by finding out that a carbon dioxide adsorbent having a functional group can be prepared.

Accordingly, it is an object of the present invention to provide a method for the simple and efficient preparation of a carbon dioxide adsorbent having an excellent selective capture capacity for carbon dioxide.

The present invention relates to a method for producing a carbon dioxide adsorbent having a nitrogen functional group, the method of the present invention

(i) mixing and stirring the activated carbon and amine solution; And

(ii) concentrating the stirred liquid mixture under reduced pressure with a rotary still.

The activated carbon in step (i) may be activated carbon having a specific surface area of 1200 to 1500 m ² / g and a particle size of 5 to 10 mm, but is not limited thereto.

The amine solution in step (i) includes a solution of amine dissolved in water, ethanol or methanol, preferably a solution dissolved in methanol. The concentration of the amine solution is preferably 1.0 to 3.0 M.

The amine may be monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (triethanolamine), ethylenediamine (ethylenediamine), and the like, and monoethanolamine is preferable.

The mixing ratio of the activated carbon and the amine solution may be 1: 1 to 1: 3 (w / v).

In the above steps (i) and (ii), the stirring and concentration temperature is preferably 30 to 50 ° C.

In step (ii), the boiling point difference is used to remove the solvent in a short time so that the nitrogen functional group can be impregnated into the activated carbon particles while minimizing the loss of the nitrogen functional group.

In the production method of the present invention, the steps (i) and (ii) may be repeated two or more times to increase the content of nitrogen functional groups.

The carbon dioxide adsorbent prepared according to the present invention is preferably used after drying at 40 to 60 ℃.

The carbon dioxide adsorbent prepared according to the present invention has a uniform distribution of nitrogen functional groups on the surface of the granular activated carbon, so that the carbon dioxide trapping ability is very excellent.

According to the manufacturing method of the carbon dioxide adsorbent using the amine concentration method according to the present invention, it is possible to produce a carbon dioxide adsorbent having excellent selectivity and high carbon dioxide trapping ability in a short time without excessive energy consumption. In addition, unlike the conventional impregnation method, the manufacturing method according to the present invention does not require a separate washing step, thereby reducing the generation of contaminants. In addition, the carbon dioxide adsorbent prepared according to the present invention is significantly better than the carbon dioxide adsorbent prepared by using the conventional impregnation method as well as untreated activated carbon.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are for illustrative purpose only and that the scope of the present invention is not limited to these embodiments.

Example 1-5 Preparation of Adsorbents Using Concentration (I)

Monoethanolamine (MEA) was dissolved in the following solvent at the following concentration to prepare a MEA solution.

division menstruum MEA concentration (M) Example 1 water 1.0 Example 2 ethanol 1.0 Example 3 Methanol 1.0 Example 4 Methanol 2.0 Example 5 Methanol 3.0

After mixing 10 g of coconut activated carbon (specific surface area: 1369.60 m ² / g, size: 5-10 mm, WSC-470, Calgon, USA) with 20 ml of the MEA solution prepared as described above, the temperature was maintained at 40 ° C. The resultant was stirred for 20 minutes in a rotary evaporator (Heidolph). After the stirring was completed, the nitrogen functional group was concentrated on the surface of the activated carbon using a boiling point difference by operating a cooler and a vacuum pump. After the reaction was completed, the adsorbent was dried at 50 ° C.

Example 6-8 Preparation of Adsorbents Using Concentration (II)

Monoethanolamine (MEA) was dissolved in the following solvent at the following concentration to prepare a MEA solution.

division menstruum MEA concentration (M) Example 6 Methanol 1.0 Example 7 Methanol 2.0 Example 8 Methanol 3.0

After mixing 10 g of coconut activated carbon (specific surface area: 1369.60 m ² / g, size: 5-10 mm, WSC-470, Calgon, USA) with 20 ml of the MEA solution prepared as described above, the temperature was maintained at 40 ° C. The resultant was stirred for 20 minutes in a rotary evaporator (Heidolph). After the stirring was completed, the nitrogen functional group was concentrated on the surface of the activated carbon using a boiling point difference by operating a cooler and a vacuum pump.

Then, the MEA solution was added to the concentrated adsorbent and the above procedure was repeated. After the reaction was completed, the adsorbent was dried at 50 ° C.

Comparative Example 1-3: Preparation of Adsorbent Using Impregnation Method

Monoethanolamine (MEA) was dissolved in the following solvent at the following concentration to prepare a MEA solution.

division menstruum MEA concentration (M) Comparative Example 1 water 1.0 Comparative Example 2 ethanol 1.0 Comparative Example 3 Methanol 1.0

10 g of coconut activated carbon (specific surface area: 1369.60 m ² / g, size: 5 to 10 mm, WSC-470, Calgon, USA) and 20 ml of the MEA solution prepared as described above are mixed and the reactor is maintained at 40 ° C. It was impregnated for 24 hours using a hot water bath at. After sufficient impregnation, the granular activated carbon adsorbent was separated through a vacuum filter and then dried at 50 ° C.

Test Example 1: Nitrogen Content Analysis

The nitrogen content of the surface of the adsorbents prepared in Examples 1 to 8 and Comparative Examples 1 to 3 was quantitatively analyzed using X-ray photoelectron spectroscopy (XPS: K-Alpha, Thermo Electron), and the results are shown in Table 4 below. Indicated.

division menstruum MEA concentration (M) Number of Concentrations (times) Nitrogen content (%) Example 1 water 1.0 One 2.4 Example 2 ethanol 1.0 One 2.5 Example 3 Methanol 1.0 One 2.5 Example 4 Methanol 2.0 One 3.7 Example 5 Methanol 3.0 One 4.6 Example 6 Methanol 1.0 2 2.8 Example 7 Methanol 2.0 2 4.6 Example 8 Methanol 3.0 2 4.6 Comparative Example 1 water 1.0 1.8 Comparative Example 2 ethanol 1.0 1.8 Comparative Example 3 Methanol 1.0 2.0 Untreated activated carbon 0.7

It can be seen from the results of Table 4 that the nitrogen content was increased through the MEA solution treatment. In Comparative Examples 1 to 3, in which the adsorbent was prepared using the impregnation method, the nitrogen content was 1.8 to 2.0% depending on the type of the solvent, whereas Examples 1 to 8 prepared the adsorbent using the concentration method according to the present invention. In the case of nitrogen, it was observed that the nitrogen content of 2.4 to 4.6% depending on the type of solvent and the concentration of MEA and the number of concentrations. In particular, when the MEA concentration was concentrated once or twice to 2.0 and 3.0 M, the nitrogen content was significantly increased.

Test Example 2: Carbon Dioxide Adsorption Test

In order to confirm the carbon dioxide trapped amount of the adsorbent, an adsorption test apparatus including a test gas supply unit, an adsorption reaction unit, and a gas analyzer was prepared.

A fixed bed reactor made of stainless steel with an inner diameter of 10 mm was filled with 3 g of each of the adsorbents prepared in Examples 1 to 8 and Comparative Examples 1 to 3, and the volume-based concentration of carbon dioxide, a target material to be collected, was 3000 ppm. Air flow was supplied. The feed rate was maintained at 2 LPM (liter / min), and the diluent gas was selected as dry air. In the adsorption test, the concentration change of carbon dioxide before and after the reactor was measured by a carbon dioxide analyzer (SenseAir, ASEN ALARM) at room temperature and atmospheric pressure. The results are shown in Table 5 below.

division menstruum MEA concentration (M) Number of Concentrations (times) Carbon dioxide adsorption amount (mmol / g) Example 1 water 1.0 One 0.124 Example 2 ethanol 1.0 One 0.119 Example 3 Methanol 1.0 One 0.194 Example 4 Methanol 2.0 One 0.228 Example 5 Methanol 3.0 One 0.322 Example 6 Methanol 1.0 2 0.231 Example 7 Methanol 2.0 2 0.564 Example 8 Methanol 3.0 2 0.414 Comparative Example 1 water 1.0 0.023 Comparative Example 2 ethanol 1.0 0.022 Comparative Example 3 Methanol 1.0 0.028 Untreated activated carbon 0.016

From the results in Table 5, it was confirmed that the carbon dioxide adsorption amount of 0.016 mmol / g in the case of untreated activated carbon. This is thought to be due to the low affinity for carbon dioxide, which is an acid gas, with only physical adsorption. In Comparative Examples 1 to 3, in which the adsorbent was prepared using the impregnation method, the adsorption amount of carbon dioxide was 0.022 to 0.028 mmol / g, whereas in Examples 1 to 8, which prepared the adsorbent using the concentration method according to the present invention, The carbon dioxide adsorption amount was 0.119 to 0.564 mmol / g. In particular, when methanol was used as the solvent, it showed the highest adsorption amount among the three solvents. It is presumed that this was able to induce the volatilization of methanol and the impregnation of a large amount of nitrogen functionalities at the same time as the solvent volatilized at a relatively low boiling point (64.7 ° C.).

Claims (10)

(i) mixing and stirring the activated carbon and amine solution; And
(ii) a method of producing a carbon dioxide adsorbent having a nitrogen functional group, comprising the step of concentrating the stirred mixed solution under reduced pressure with a rotary still. The method according to claim 1, wherein the specific surface area of the activated carbon is 1200 to 1500 m ² / g and the particle size is 5 to 10 mm. The method according to claim 1, wherein the amine solution is a solution of amine dissolved in water, ethanol or methanol. 4. A process according to claim 3, wherein the amine solution is a solution of amine dissolved in methanol. The method according to claim 1, wherein the concentration of the amine solution is 1.0 to 3.0 M. The method of claim 1, wherein the amine is monoethanolamine (MEA). The method of claim 1, wherein the mixing ratio of the activated carbon and the amine solution is 1: 1 to 1: 3 (w / v). The process according to claim 1, wherein the stirring and concentration temperatures in the steps (i) and (ii) are 30 to 50 ° C. The process according to claim 1, wherein steps (i) and (ii) are repeated twice to increase the content of nitrogen functional groups. The method of claim 1 further comprising the step of drying the carbon dioxide adsorbent at 40 to 60 ° C.