JP4747402B2 - Adsorbent for aldehydes - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a deodorizing adsorbent for the purpose of adsorbing and removing aldehydes.
[0002]
[Prior art]
Deodorizing filters are widely used by being mounted on air purifiers, and various attempts have been made to improve the adsorptivity of adsorbents for deodorizing filters by attaching chemical substances. In particular, it is a well-known technique to attach an amine compound in order to stably adsorb aldehydes, which are strong odorous substances. JP-A 56-53744 discloses that aniline is attached. In JP-A-71193, JP-A-10-99418, JP-A-5-23588, etc., an aromatic acid amine compound having an amino group and an acidic functional group or an aromatic aminocarboxylic acid is attached to an aromatic ring. Is disclosed.
[0003]
By the way, the odor is composed of a plurality of components, and there are various types depending on the space. For example, cigarette odor, which is a typical odor in a living room space, is a mixed odor such as acetaldehyde, ammonia, acetic acid, and hydrocarbon, and hydrogen sulfide derived from automobile exhaust gas is also present in the car interior space. In order to cope with such various odors, Japanese Patent Application Laid-Open No. 7-136502 discloses a technique for simultaneously adsorbing aldehydes and ammonia with an adsorbent adsorbed with aminobenzenesulfonic acid.
[0004]
[Problems to be solved by the invention]
However, aminobenzene sulfonic acid, aminobenzoic acid, etc. disclosed in JP-A-5-23588, JP-A-7-136502, JP-A-10-71193, and JP-A-10-99418 are all included. These are compounds in which an acidic functional group is directly bonded to the aromatic ring of an aromatic amine, but these compounds show good aldehyde adsorption when the acidic functional group is used in the proton form, but are basic substances. In other words, when the pH of the adsorption atmosphere is in a neutral to basic region, there is a disadvantage that the aldehyde adsorptivity is suddenly lost.
[0005]
This is presumed to be due to the effect of π electron resonance between the aromatic ring and the acidic functional group directly bonded to it, and this phenomenon is present, so in the prior art, the amount of the basic compound mixed with the aromatic amine is adjusted. That is, there is a limitation that the adsorbent must be used in an acidic to weakly basic region. For this reason, in the field of the air purifier where the adsorption target gas is diversified, there is a drawback that the specification of the deodorizing filter is largely regulated.
[0006]
An object of the present invention is to solve such problems and to provide an adsorbent that stably adsorbs aldehydes in a wide pH range where the adsorption atmosphere is strongly acidic to strongly basic.
[0007]
[Means for Solving the Problems]
The adsorbent for aldehydes of the present invention is an adsorbent for aldehydes formed by attaching an organic acid having an amino group and an aromatic ring in the same molecule and / or a salt thereof to a porous carrier. , Aminophenylacetic acid or (aminophenyl) methanesulfonic acid .
[0008]
If an organic acid (or a salt thereof) having an alkane carbon atom between an amino group and an aromatic ring, for example, an organic acid (or a salt thereof) having an (aminoalkyl) phenyl group, the amino group has an alkane carbon atom. Therefore, the π electron resonance of the phenyl group is interrupted at the alkane carbon atom portion, and the amino group does not participate in the π electron resonance of the aromatic ring. In addition, if an organic acid (or a salt thereof) having an alkane carbon atom between an acidic functional group and an aromatic ring, for example, an organic acid (or a salt thereof) having a (aminophenyl) methane skeleton, the aminophenyl group is Since it is bonded to the acidic functional group of the organic acid via the alkane carbon atom, the π electron resonance of the phenyl group is interrupted at the alkane carbon atom portion, and the amino group on the aminophenyl group and the acidic functional group are conjugated double bonds. Therefore, even if the organic acid becomes a basic salt, π electron resonance from the acidic functional group does not interfere with the amino group. Therefore, according to the adsorbent of the present invention, the adsorptivity of aldehydes can be stably expressed in a wide pH range from strong acidity to strong basicity.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0010]
The adsorbent for aldehydes of the present invention is obtained by adhering an organic acid selected from aminophenylacetic acid and (aminophenyl) methanesulfonic acid to a porous carrier .
[0011]
The organic acid according to the present invention, 4 - and amino phenylacetic acid, such as amino phenyl acetic acid, (aminophenyl) methane sulfonic acid, such as (4-aminophenyl) methane sulfonic acid.
[0012]
These organic acid salts are preferably alkali metal or alkaline earth metal salts such as sodium, potassium and magnesium salts, but are not limited thereto.
[0013]
Examples of the porous carrier to which these organic acids and / or salts thereof are impregnated include activated carbon, alumina, zeolite, silica and diatomaceous earth, but are not limited thereto, and activated carbon is preferably used. When producing the adsorbent for aldehydes of the present invention, the method for attaching the organic acid and / or salt thereof to the porous carrier is not particularly limited, and there are ordinary methods such as dipping and spray coating. Can be adopted. In general, an amino aromatic acid compound is neutrally insoluble in water, but in the present invention, a strongly basic solution can be used as a solvent, so that a high-concentration solution can be obtained. When applying by law, efficient attachment can be performed, which is advantageous. The amount of attachment to the porous carrier is not particularly limited, but in general, the amount of attachment to the porous carrier is preferably about 0.1 to 30% by weight.
[0014]
When the adsorbent for aldehydes of the present invention thus obtained is to be adsorbed together with an acid gas, the adsorption system may be a strongly basic atmosphere. Acid gas can also be adsorbed, and ammonia can be adsorbed together with aldehydes by making the adsorption system a strongly acidic atmosphere, which is extremely effective for deodorizing a wide variety of odors.
[0015]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0016]
Example 1
An aqueous solution in which sodium hydroxide was mixed with 0.5 g of 4-aminophenylacetic acid at a molar ratio of 1.0 / 1.0 and 1.0 / 3.0, respectively, and dissolved in 100 mL of water, and 4-aminophenylacetic acid 7 g of activated carbon was mixed with each 0.5 wt% aqueous solution and gently stirred, and allowed to stand for 1 hour. This was collected by filtration and dried at 110 ° C. for 3 hours to obtain the adsorbent of the present invention. The obtained adsorbent is obtained by adhering 3 to 5% by weight of 4-aminophenylacetic acid or 4-aminophenylacetic acid sodium salt to activated carbon.
[0017]
Each 1 g of these activated carbons is filled in a 14 mmφ glass tube, clean air containing 50 ppm acetaldehyde is aerated at a flow rate of 1 liter per minute at room temperature, and the acetaldehyde concentration before and after passing through the adsorbent is measured over time. Thus, the acetaldehyde removal rate was calculated and the acetaldehyde adsorptivity was evaluated. For comparison, the adsorptivity of acetaldehyde was similarly evaluated for activated carbon not impregnated with 4-aminophenylacetic acid. These results are shown in FIG.
[0018]
As is clear from FIG. 1, 4-aminophenylacetic acid or its sodium salt impregnated showed a stable acetaldehyde removal rate regardless of the pH (molar ratio of sodium hydroxide).
[0019]
Example 2
In Example 1, (4-aminophenyl) methanesulfonic acid was used instead of 4-aminophenylacetic acid, and the molar ratio of sodium hydroxide was changed as shown in FIG. Evaluation was performed and the results are shown in FIG.
[0020]
As is clear from FIG. 2, (4-aminophenyl) methanesulfonic acid or its sodium salt is also stable acetaldehyde removal, regardless of pH (molar ratio of sodium hydroxide), similarly to 4-aminophenylacetic acid. Showed the rate.
[0021]
Comparative Example 1
In 100 mL of a 0.5 wt% aqueous solution of 4-aminobenzoic acid and 0.5 g of 4-aminobenzoic acid, sodium hydroxide was mixed at a molar ratio of 1.0 / 1.0, and dissolved in 100 mL of water. Then, 7 g of activated carbon was mixed and gently stirred, and allowed to stand for 1 hour. This was collected by filtration and dried at 110 ° C. for 3 hours to obtain two adsorbents to which 4-aminobenzoic acid and its sodium salt were attached. About this adsorbent, the adsorptivity of acetaldehyde was evaluated by the same method as in Example 1, and the results are shown in FIG.
[0022]
From FIG. 3, it can be seen that aminobenzoic acid has acetaldehyde adsorptivity in the acid state, but the sodium salt significantly deteriorates with time and cannot be used in the alkaline region.
[0023]
【The invention's effect】
As described above in detail, according to the present invention, an adsorbent capable of adsorbing aldehydes stably in a pH range where the adsorption atmosphere is strongly acidic to strongly basic is provided.
[Brief description of the drawings]
1 is a graph showing the change over time in the aldehyde removal rate of aminophenylacetic acid and its sodium salt in Example 1. FIG.
2 is a graph showing the change over time in the aldehyde removal rate of (4-aminophenyl) methanesulfonic acid and its sodium salt in Example 2. FIG.
FIG. 3 is a graph showing the change over time in the aldehyde removal rate of aminobenzoic acid and its sodium salt in Comparative Example 1.

Claims (5)

An adsorbent for aldehydes formed by attaching an organic acid having an amino group and an aromatic ring in the same molecule and / or a salt thereof to a porous carrier, wherein the organic acid is aminophenylacetic acid or (aminophenyl) methane An adsorbent for aldehydes, which is a sulfonic acid . The adsorbent for aldehydes according to claim 1, wherein the aminophenylacetic acid is 4-aminophenylacetic acid. The adsorbent for aldehydes according to claim 1, wherein the (aminophenyl) methanesulfonic acid is (4-aminophenyl) methanesulfonic acid. The adsorbent for aldehydes according to any one of claims 1 to 3 , wherein the organic acid salt is an alkali metal salt and / or an alkaline earth metal salt. The adsorbent for aldehydes according to any one of claims 1 to 4 , wherein the porous carrier is one or more selected from the group consisting of activated carbon, alumina, zeolite, silica, and diatomaceous earth.

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