JPH06102153B2 - Modification method of carbon black - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for modifying a carbon black for the purpose of imparting to the carbon black the ability to selectively adsorb an acidic gas such as carbon dioxide. .

[Conventional technology]

Carbon dioxide is used not only for urea synthesis, but also for casting (mold hardening aid), welding (inert gas for welding), dry ice production, etc. Does it industrially heat limestone? It is also manufactured by burning coal or the like.

In general, carbon dioxide is separated and purified by absorbing it in a cold aqueous solution of a carbonate such as sodium carbonate or amines such as ethanolamine, and then heating and collecting it. It is unavoidable that water is mixed in carbon dioxide, and there are disadvantages such that the process is restricted because the liquid absorbent is used.

As a large-scale application of carbon dioxide, which has recently received attention,
Enhanced oil recovery is an example. This is to inject carbon dioxide into the oil layer targeted for secondary recovery to reduce the viscosity of crude oil and recover crude oil. Here, combustion exhaust gas etc. serve as a carbon dioxide source, so it is effective. The development of new carbon dioxide separation technology is desired.

On the other hand, as a life support system for manned space equipment such as spacecraft and space bases, a device for removing carbon dioxide released from the human body is indispensable.
It is said that a solid adsorbent which is easy to handle under zero gravity is suitable.

[Problems to be solved by the invention]

Since amines such as the already mentioned ethanolamine have the property of selectively absorbing acidic gases such as carbon dioxide, carbon dioxide can be adsorbed and separated in principle if a resin with an amine structure is used. However, in order to impart a sufficient function as an adsorbent to the resin, it is necessary to sufficiently increase the gas contact area by a method such as making the resin into a porous body or atomizing.

[Means for solving problems]

The inventors conducted extensive research to create an adsorbent that is completely different from the adsorbent in which a resin having an amine structure has a geometric shape such that the gas contact area becomes large. After having thionyl halide act on the carbon black which it has, by acting an azo compound of an alkali metal, and then acting on polyethyleneimine, the ability to selectively adsorb an acidic gas such as carbon dioxide to the carbon black is obtained. Find that it will be granted,
The present invention has been completed. That is, the present invention provides a method for modifying a carbon black, which comprises reacting a carbon black having a carboxyl group with a thionyl halide, followed by an azide compound of an alkali metal, and then with a polyethyleneimine. is there.

In the method for modifying a carbon black of the present invention, first, by reacting a thionyl halide SOX ₂ (where X is a halogen) such as thionyl chloride or thionyl bromide, the carboxyl groups present on the surface of the carbon black particles are COX
Group, and then by the action of an alkali metal azide MN ₃ (where M is an alkali metal) such as sodium azide, potassium azide, etc. to a —CON ₃ group, and then polyethyleneimine By the action of, the carbon black is endowed with the ability to bond with polyethyleneimine and selectively adsorb an acidic gas such as carbon dioxide.

This adsorption capacity is due to the fact that the polyethyleneimine used for the reforming of the present invention has a property of selectively absorbing an acidic gas such as carbon dioxide, but the polyethyleneimine itself is at room temperature. It is a liquid or viscous fluid and cannot be handled as a solid absorbent. However, the carbon black to which polyethyleneimine is bound by the modification method of the present invention is a powdery solid, and it is formed into an arbitrary shape by the powdery state or a method such as compression, and an acidic state such as carbon dioxide. It can be used for adsorption separation of gas.

Carbon black is classified according to its manufacturing method into fannes black, channel black, lamp black, thermal black, acetylene black, and the like. Since the carboxyl group is present and the content of the carboxyl group can be increased by a method such as nitric acid oxidation, the modification method of the present invention can be applied to any carbon black.

The reforming method of the present invention will be specifically described. For example, in order to modify 10 g of the carbon black, 50 to 120 ° C. is added to the carbon black in a solvent such as 0 to 5000 ml, preferably 150 to 300 ml of benzene, Preferably 1 to 1 at 70 to 80 °
000 ml, preferably 20-50 ml of thionyl halide 1-1
After stirring for 50 hours, preferably 20 to 80 hours, the solvent and unreacted thionyl halide are distilled off under reduced pressure, and 20 to 5000 ml, preferably 100 to 200 ml of a solvent such as tetrahydrofuran, 50 to 20 ° C, preferably -5 to 5 ° C
5 × 10 ^{-4 to} 5 mol, preferably 10 ^-2 to 10 ^-1 mol of an azide compound of an alkali metal for 1 to 100 hours, preferably 5
After stirring for 20 hours, the carbon black is separated by a method such as passing, and after washing with cold water, cold methanol, etc., 20 to 5000 ml, preferably 150 to 300 ml of a solvent such as dimethyl sulfoxide. Among them, at 20 to 150 ° C, preferably 50 to 100 ° C, 10 to 2000
g preferably 100-200 g of polyethyleneimine 0.5-500
It is allowed to act with stirring for 10 to 30 hours, and then unreacted polyethyleneimine may be removed by a method such as Soxhlet extraction using water or methanol as a solvent.

Next, the present invention will be further described with reference to examples.

Example 1 Modification of a carbon black by the method of the present invention was carried out as follows. First, Colombian Carbon
ian Carbon Co.) carbon black Neospectra II (specific surface area 906m ² / g, carboxyl group content 0.4m mol / g) 5g 5mm
After drying under reduced pressure of Hg at 10 ° C. for 5 hours, the mixture was mixed with 18 ml of thionyl chloride in 120 ml of benzene and reacted at 70 ° C. for 50 hours while stirring. Then, benzene and unreacted thionyl chloride were distilled off from this mixture at room temperature under reduced pressure of 5 mmHg, and further dried at 110 ° C. under reduced pressure of 5 mmHg for 5 hours, and then 70 ml of tetrahydrofuran.
Was added and the temperature of this mixture was brought to 0 ° C.

Then add 1.3 g of sodium azide (0.02 mo
l) was dissolved in a small amount of water and added, and the mixture was reacted at 0 ° C. for 10 hours with stirring. After the reaction, separate and wash several times with water at 0 ° C, and then wash with methanol at 0 ° C.
It was dried at room temperature under reduced pressure of mHg for 10 hours. Then
1.5 g of this carbon black and 20 g of polyethyleneimine (average molecular weight of about 30,000) manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd. were added to 30 ml of dimethyl sulfoxide, and the mixture was reacted at 80 ° C. for 24 hours while stirring, and then methanol was added as a solvent to 100 ml.
3.1 g of carbon black modified by the method of the present invention by performing Soxhlet extraction for a period of time to remove unreacted polyethyleneimine and drying at 120 ° C. for 5 hours under a reduced pressure of 5 mmHg (per 1 g of carbon black The amount of polyethyleneimine bound was 1.07 g.

Experimental Example 1 2.0 g of the carbon black modified in the same manner as in Example 1 was placed in an eggplant-shaped flask having an internal volume of 100 ml and kept at 120 ° C. for 1 hour while exhausting under a reduced pressure of 5 mmHg, and then at room temperature under a reduced pressure of 5 mmHg. I left it until.

Next, this eggplant-shaped flask was combined with a container containing 1 atm of carbon dioxide 3, and carbon dioxide was brought into contact with the carbon black at room temperature, and the amount of carbon dioxide adsorbed was measured by a gas biuret method.

The adsorption of carbon dioxide starts immediately and 1.76 after 10 minutes.
The amount of carbon dioxide adsorbed 60 minutes after the adsorption of m mol carbon dioxide reached 4.61 mmol.

Next, using a vacuum pump, the inside of the eggplant-shaped flask containing this carbon black was evacuated for 20 minutes at room temperature under a reduced pressure of 5 mmHg to release the adsorbed carbon dioxide, and then this eggplant-shaped flask was operated at 1 atm. It was combined with a container containing carbon dioxide 3 and carbon dioxide was brought into contact with the carbon black at room temperature.

The adsorption of carbon dioxide starts immediately, and after 10 minutes, 1.
72m mol of carbon dioxide was adsorbed, and the amount of adsorbed carbon dioxide after 60 minutes reached 4.50m mol.

After that, even if the above operation was repeated, no change was observed in the adsorption rate and adsorption amount of carbon dioxide.

Experimental Example 2 2.0 g of the carbon black modified in the same manner as in Example 1 was placed in a round-bottomed flask having an internal volume of 100 ml, kept at 120 ° C. for 1 hour while exhausting under a reduced pressure of 5 mmHg, and then at room temperature under a reduced pressure of 5 mmHg. I left it until.

Next, this eggplant-shaped flask was combined with a container containing 1 atm of carbon dioxide 3, and carbon dioxide was brought into contact with the carbon black at room temperature, and the amount of carbon dioxide adsorbed was measured by the gas visual method.

The adsorption of carbon dioxide starts immediately and 1.76 after 10 minutes.
After adsorbing 60 mol of carbon dioxide, the amount of carbon dioxide adsorbed after 60 minutes reached 4.61 mmol.

Next, this carbon black was heated to 120 ° C. under 1 atm, and the amount of carbon dioxide released was measured by a gas view method. Carbon dioxide was released promptly, reaching 4.59 mmol after 20 minutes. As a result of analyzing the released gas by a gas chromatograph, the released gas was only carbon dioxide, and other components were not detected.

After that, after allowing to cool while passing nitrogen into the eggplant-shaped flask containing the carbon black from which this carbon dioxide was released, it was combined with a container containing 1 atm of carbon dioxide 3, and carbon dioxide was contacted with the carbon black at room temperature. Let

The adsorption of carbon dioxide starts immediately, and after 10 minutes, 1.
75m mol of carbon dioxide was adsorbed, and the amount of carbon dioxide adsorbed after 60 minutes reached 4.59m mol.

When this carbon black is heated to 120 ° C under 1 atm,
Carbon dioxide is released promptly, and the amount released is 20 minutes later 4.
Reached 59 mmol.

After that, no change was observed in the adsorption rate and the adsorption amount of carbon dioxide even if the above operation was repeated.

〔effect〕

As described above in detail, the use of the carbon black modified by the method of the present invention as the adsorbent brings about an effect that carbon dioxide can be easily separated from the mixed gas.

The carbon dioxide adsorption capacity of the carbon black modified by the method of the present invention is due to the fact that the polyethyleneimine used for the modification has a property of selectively absorbing an acidic gas. The carbon black also produces an effect that it can be used for adsorption separation of acidic gas other than carbon dioxide, for example, hydrogen sulfide.

Claims (1)

[Claims] 1. A method for modifying a carbon black, which comprises reacting a carbon black having a carboxyl group with a thionyl halide, an azide compound of an alkali metal, and then a polyethyleneimine.