JPS60202735A - Adsorbent of aldehydes in gaseous phase - Google Patents

Abstract

PURPOSE:To obtain an adsorbent capable of removing aldehydes in a gaseous phase for a long period by depositing an aliphatic primary amine or a secondary amine on an activated carbon material having specified pore volume. CONSTITUTION:An aliphatic primary amine or a secondary amine having <=10mm.Hg vapor pressure at 20 deg.C is deposited on an activated carbon material having <=3.00Angstrom pore diameter and >=0.4cc/g pore volume wherein the volume occupied by the pores having <=30Angstrom pore diameter is regulated to >=80%. The adsorptive performance is further improved by depositing said amine buffered with a weak acid (e.g., acetic acid) having 3.5-5.5pKa. The obtained adsorbent shows an excellent adsorptive performance to poisonous and highly irritant gaseous aldehyde, and the rescattering of the deposited chemicals is eliminated, and the deterioration due to the adsorption of other organic gases is reduced. The ventilation resistance is low when used in an automobile or in a living room, and the air conditioning effect is not decreased significantly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an activated carbon adsorbent that exhibits excellent adsorption performance for aldehydes in the gas phase.

There is an increasing demand for a filter that efficiently removes irritating components (eg, acetaldehyde, formaldehyde) from cigarette smoke in a small, closed space.

Conventional granular activated carbon adsorbents are currently widely used because they adsorb harmful substances in the air (eg, benzene, chloroform, etc.) with a relatively high equilibrium adsorption amount even at low concentrations. However, these adsorbents have the disadvantage that the equilibrium adsorption amount is low for highly irritating aldehyde gas components such as formaldehyde, acetaldehyde, and acrolein, and that the adsorbed gas is concentrated and desorbed. Was.

In order to eliminate the above drawbacks, for example, Japanese Patent Application Laid-Open No. 56-53744
As described in the above publication, a method has been attempted in which aldehydes in the gas phase are removed using an adsorbent in which activated carbon is impregnated with aniline. However, this method does not give very satisfactory results. The activated carbon used is regular coconut shell activated carbon! 2 1- bayya-sxr,a
a, +4-1+-1+ -P A1. 7+11? +
Since the pore volume of ym−9 or less is small, the adhesive (
However, the impregnant (aniline) itself has the disadvantage of being unstable over time when adsorbing aldehydes, and is said to be carcinogenic. However, there were problems in putting it into practical use.

As a result of studies aimed at improving this conventional technology, the present inventors have discovered that an adsorbent made by impregnating a specific amine compound with an activated carbon material having a unique pore structure has no adverse effect on the human body and has no adverse effect on the human body. The present invention was achieved by discovering that aldehydes in the phase can be efficiently removed over a long period of time.

The pore diameter and pore volume of activated carbon are determined by Cranston-Inkley (C
Ranston-Inkley) calculation method. The relationship between the multimolecular adsorption layer and the relative pressure is expressed by the modified Frenkel-Halsey (t(X) = 3.54(5/1n(PS/P))'f).
ey) (Keii Tominaga "Adsorption" Kyoritsu Shuppan).

However, the ratio (1,5
The value multiplied by 84×10−3) was regarded as the total pore volume with a pore diameter of 3ooX or less.

First, the activated carbon material used in the present invention will be explained. The activated carbon material used in the present invention has a pore volume of 0.4 cc/f or more with a pore diameter of 300X or less, and a pore diameter of ao
It is essential that the activated carbon material has a ratio of pore volume of X or less to pore volume of pore diameter of 300X or less (hereinafter abbreviated as α) of 80% or more.

That is, the pore volume Vl with a pore diameter of 300X or less is 0.4e.
If an activated carbon material is used in which the ratio α of the pore diameter aoX or less is less than 80%, no matter how much the amine compound of the present invention is impregnated, the impregnation effect and lifespan will be insufficient, resulting in unfavorable results. I won't give it.

The above activated carbon material having a specific pore structure is manufactured, for example, by the following method. Namely, (1) a method in which regenerated cellulose fibers or novolac type phenolic resin fibers are carbonized and then subjected to high temperature activation treatment with steam; (2) a method in which commercially available granular coconut shell activated carbon is subjected to reactivation treatment with steam at high temperature, etc. be able to.

Of course, the pore volume of pore diameters of 300X or less is 0.4c.
The method is not limited to the above method as long as it provides activated carbon with a ratio of 80% or more of the pore volume having a diameter of c/f' or more and a pore diameter of aoX or less.

The activated carbon material may be in the form of powder, granules, or fibers as described above, but from the viewpoint of adsorption and ease of impregnation, fine particles or powder, particularly fine powder with a particle size of 30 μm or less, are preferable. .

The present invention uses the above-mentioned activated carbon material to physically increase the adsorption area of the impregnating layer and efficiently remove aldehydes in the gas phase.On the other hand, the impregnant itself used is a known one. In contrast, it chemically adsorbs aldehydes without any time dependence, and these physical and chemical effects work synergistically to achieve remarkable aldehyde adsorption.
This is the first time it has been removed.

Next, the amine compound used in the present invention will be explained. The amine compound used in the present invention has a vapor pressure of 1 O at 20°C.
+trmHt or less aliphatic primary amine or secondary
It is essential that it be a class amine. Among primary amines/secondary amines, those having a vapor pressure exceeding 10 rmnHf have many problems such as scattering after impregnation or emitting odor. As the aliphatic primary amine or secondary amine used in the present invention, monoethanolamine, N-aminoethylethanolamine, N-methylethanolamine, ethylmonoethanolamine, dimethylethanolamine,
Ethanol-based amines such as diethylethanolamine; monoisopropanolamine: triethylenetetramine;
Tetraethylenepentamine, hexamethylenediamine,
Examples include benzylamine, xylylene diamine, etc., and preferably the above-mentioned ethanol amines (in addition, the aliphatic amine of the present invention is an amine compound in which the N atom is not directly bonded to the aromatic ring; (Includes those in which a CH2 group is interposed between the aromatic ring and the N atom, such as amines and xylylene diamines). Note that aliphatic tertiary amines are not used in the present invention because they have low reactivity with aldehydes. In addition, aromatic amines (aniline, phenylenediamine, naphthylamine, etc.) are harmful to the human body, as mentioned above, and decompose during storage (filters made with these amines are stored), resulting in poor adsorption performance. Since it decreases over time, it is not adopted in the present invention.

Further, the adsorbent of the present invention is produced by impregnating the above amine compound onto an activated carbon material, and the amount of the amine compound impregnated onto the activated carbon material is 0.1 to 50% by weight, preferably 1 to 30% by weight. . Impregnation is carried out at a vapor pressure of 10 mm at 20°C) II
A method of spraying a solution of aliphatic primary amine or secondary amine of F or less on an activated carbon material and then drying it, or immersing a predetermined amount of the activated carbon material in a solution of the amine compound with a predetermined concentration and filtering it. This can be achieved by

Furthermore, the amine has a pKa of 3.5 to 3.5 as shown below.
When a weak acid buffered with 5.5 is impregnated, the removal effect on aldehyde gas is further improved. Namely, acetic acid, propionic acid, butyric acid, phenolic acid, capric acid, enanthic acid (
CH3(CH2)5C0OH), pelargonic acid (C
Examples include saturated monocarboxylic acids such as H3-(CH2)7-Coon), lactic acid, succinic acid, benzoic acid, glutamic acid, carboxymethylcellulose (CMC), alginic acid, polymetallic acid, and the like. Buffering methods include a method of adding a weak acid or a salt of a weak acid to an aqueous amine solution, or a method of adding a weak acid or a salt of a weak acid to an activated carbon slurry on which an amine has been adsorbed.

The adsorbent according to the present invention is applied, for example, to filter applications. A filter to which the adsorbent of the present invention is applied is produced by (1) impregnating the amine of the present invention on the finely powdered activated carbon material of the present invention, and then impregnating it with a solution such as sodium alginate, carboxymethyl cellulose, water glass, silica sol, or polystyrene solution. A method in which the activated carbon material is dispersed, applied to paper, nonwoven fabric, foam material, honeycomb filter, porous granular material, etc., and dried; (g) A method in which the amine of the present invention is impregnated with a finely divided activated carbon material and then sprinkled on a nonwoven fabric, tow, textile, etc. with an adhesive.

In particular, coating filters with honeycomb-like filters or porous urethane foam (product name: Ever Light Scotto; Prigiston Tire KK) have a good balance between adsorbent contact efficiency with aldehyde gases and air permeability. Use is preferred.

The adsorbent of the present invention has an amine with a specific molecular structure impregnated on an activated carbon bed with a specific pore distribution, so it exhibits excellent adsorption performance for harmful and highly irritating aldehyde gas. It has the characteristics that there is no re-scattering of chemicals, and because it chemically adsorbs selectively only to aldehyde gas, there is little deterioration due to adsorption of other organic gases.

Therefore, if a filter using the adsorbent of the present invention is installed in the interior of a car, train car, coffee shop, scissor art gallery, playground, or living room where formaldehyde, acetaldehyde, etc. are likely to be filled, the above harmful gases can be efficiently removed. It has the advantage of eliminating airflow, low ventilation resistance, and less deterioration of indoor heating and cooling effects. Also, cigarettes
When used as an adsorbent for filters, it efficiently removes the irritating components of tobacco smoke, thereby improving smoking taste.

Examples of the present invention will be described below, but the present invention is not limited to these Examples in any way.

Example 1 A 1.5 d recycled cellulose fiber was impregnated with 10% by weight of ammonium phosphate, dried, and heated from room temperature to 6 % by weight in an inert gas.
Heat treatment was performed to 300C at a heating rate of 0C/h to obtain flame-resistant fibers. Next, this flame-resistant fiber was heated to 900° C. at a heating rate of 400° C./hr in an inert gas containing water vapor, maintained at that temperature for 1 hr, and subjected to an activation treatment.

vl is 0.78 cc/? , α-92% fibrous activated carbon was obtained. 60 parts of the above activated carbon material, offshore water temperature is 5R
Activated carbon paper was made with a Yankee type wet paper machine to a weight of 452/m2 using a composition of 40 parts of NBKP pulp (softwood Pulichinda kraft pulp) beaten to 30° and 7 parts of polyvinyl alcohol fiber. Paper thickness ◆0.
A 20+as+ activated alumina paper was obtained. Next, the carbon paper was processed using a corrugating machine to a pitch width of 3.1 mm and a pitch height of 2.1 mm.
The body was formed into a corrugated pole sheet on one side.

The single-sided corrugated sheet was coated with a layer length of 2. After slitting it into 0 cm, it was rolled up into a disk shape with a diameter of 15 crn to obtain a nicum-shaped filter.

The honeycomb filter was immersed for 30 minutes in a 20% by weight aqueous solution of aminoethyl ethanolamine (vapour pressure at 20°C of 0.01+llInHf or less) whose pH was adjusted to 7kmM with succinic acid, and then air-dried. A filter was obtained in which 20% by weight of impregnated with. The aldehyde gas adsorption properties of the obtained filters were evaluated based on the following method.

That is, the filter was loaded into a commercially available small indoor air purifier (Air Refle, manufactured by Matsushita Electric Works).

The air purifier contains about 2.7-m of acetaldehyde gas.
Installed in the center of a plastic box filled with ppm, the wind was 0.53rr? I drove at /jth. The decay curve of acetaldehyde gas was measured over 30 minutes using an FrD gas chromatograph. Assuming that the attenuation curve is a first-order reaction equation, the reaction rate constant was calculated and used as a measure of the filter's ability to absorb acetaldehyde gas. Table 1 shows the acetaldehyde adsorption performance of the filter based on the above evaluation. In addition, in Table 1, 3 hours after warming
rs, 1 week indicates the filter performance after being left for 3 hours after filter production and for 1 week. The location where the filter was left was a movie theater.

Comparative Example 1 The activation conditions of Example 1 were changed to 850° C. for 0.5 hr, and fibrous activated carbon with V1 = 0.35 cc/fα = 97% was obtained.

Using the activated carbon, paper making, corrugated holes,
Example 1 by impregnating 20% by weight of succinic acid neutralized aminoethylethanolamine to form a honeycomb filter
We attempted to evaluate the performance of acetaldehyde using the same method. Table 1 shows the results.

Comparative Example 2 The regenerated cellulose-based activated carbon fiber obtained in Example 1 was impregnated and impregnated with acetic acid magnezwood and then subjected to reactivation treatment in a steam-containing combustion gas atmosphere at 900°C, resulting in a Vl of 0.90 c.
Fibrous activated carbon with c/t α of 55% was obtained. Using this, paper, cardboard, and honeycomb filters were made in the same manner as in Example 1, impregnated with 20% by weight of succinic acid neutralized aminoethylethanolamine, and the performance of acetaldehyde was evaluated in the same manner as in Example 1. I tried.

Table 1 shows the results.

Example 2 A 7-borac type phenolic resin fiber of 2d was activated by holding it at a temperature of 900° C. for 2 hours at a heating rate of 400° C./h in an inert gas containing water vapor.

Fibrous activated carbon with a Vl of 0.80 cc/f α of 95% was obtained. Using this, paper, cardboard, and honeycomb filters were made in the same manner as in Example 1, impregnated with 20% by weight of propionic acid neutralized aminoethylethanolamine, and the performance of acetaldehyde was evaluated in the same manner as in Example 1. I tried. Table 1 shows the results.

Comparative Example 3 Commercially available coconut shell activated carbon Vl = 0.30 cc/? After coarsely pulverizing α=97%, it was pulverized to a fine powder with an average particle size of 20 μm using a ball mill. After making paper and corrugating the activated carbon in the same manner as in Example 1, a vanicum filter was made, and after being impregnated with 20% by weight of propionic acid neutralized aminoethylethanolamine, it was processed in the same manner as in Example 1. The absorption rate of acetaldehyde was measured. The results are shown in Table 1.

Comparative Example 4 After pulverizing commercially available coal-based activated carbon V1 = 0.50 cc / f α = 60% to an average particle size of 20 μm using a pole mill, paper, cardboard, and honeycomb filters were made in the same manner as in Example 1. 20 parts of amine ethyl ethanolamine
% impregnation treatment and the absorption rate of acetaldehyde was measured. The results are shown in Table 1.0 Comparative Example 5 The honeycomb filter of Example 2 was impregnated with 20% by weight of propionic acid-neutralized tributylamine, and the absorption rate of acetaldehyde was measured.

Comparative Example 6 The honeycomb filter of Example 2 was impregnated with 20% by weight of propionic acid-neutralized triethanolamine, and the absorption rate of acetaldehyde was measured.

Example 3 The coconut shell activated carbon of 8 to 14 meshes used in Comparative Example 3 was coarsely ground into 50 to 105 meshes, and subjected to reactivation treatment in a rotary kiln furnace for 5 hours in a combustion gas atmosphere at 900°C, resulting in Vl = 0.59. cc/? Activated carbon with α=85% was obtained.

The activated carbon was pulverized in a ball mill to an average particle size of 20 μm. Using the activated carbon, the activated carbon was made into paper, stage molded, and honeycomb filtered in the same manner as in Example 1, and then impregnated with an aqueous solution of N-methylethanolamine adjusted to pH 7 with acetic acid and dried to obtain 20% by weight of the amine. After impregnation, the absorption rate of acetaldehyde was measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 7 Actual 1 m Example, 2 aniline was applied to the honeycomb filter of 3.
The absorption rate of acetaldehyde was measured in the same manner as in Example 1 after 0% by weight impregnation treatment. The results are shown in Table 1. It can be seen that when using aniline, the adsorption properties decrease significantly over time.

Comparative Example 8 Triethylenediamine (1,4 diazabicyclo[2,2,2]octane) in the honeycomb filter of 7F[3]
The absorption rate of acetaldehyde was measured in the same manner as in Example 1.

The results are shown in Table 1.

Comparative Example 9 The honeycomb filter of Example 3 was impregnated with 20% by weight of n-propylamine (vapor pressure 250 +++ mHf at 20°C), and the absorption rate of acetaldehyde was measured. The results are shown in Table 1.

Claims (3)

[Claims] (1) Pore diameter a, pore volume below ooX is 0.4 c
C71 or more, and the ratio of the pore volume of the pores having a pore diameter of aoX or less is 80% or more, and an aliphatic primary amine or a secondary
An adsorbent for aldehydes in a gas phase, characterized by impregnating a class amine. (2) The adsorbent according to claim (1), wherein the aliphatic amine is an ethanol amine. (3) The adsorbent according to claim (1), wherein the amine is buffered with a weak acid having a pKa of 3.5 to 5.5.