JP4554004B2 - Lower aldehyde adsorbent - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an adsorbent having excellent adsorption performance for lower aldehydes such as formaldehyde and acetaldehyde.
[0002]
[Prior art]
Lower aldehydes represented by formaldehyde, acetaldehyde and the like are all toxic gases having a unique irritating odor. Among them, formaldehyde has a provisional value of 0.5 ppm in the air, and acetaldehyde is designated as a malodorous substance. Formaldehyde sources include formaldehyde manufacturing plants, urea, melamine, phenol, etc., and resin manufacturing plants using formaldehyde as raw materials, processing plants that use these resins, and building materials and furniture that use these resins. For example, a factory for manufacturing various processed products. It is also said that it is generated from incomplete combustion of formalin and petroleum stoves used as disinfectants, and is also contained in a lot of sidestream smoke. Recently, formaldehyde generated from building materials has become a problem even in rooms using new building materials. As a source of acetaldehyde, it is generated at the time of heat treatment of sewage sludge in addition to a manufacturing factory for acetaldehyde and its derivatives, and is also contained in the mainstream smoke of cigarettes. In recent years, harmfulness and odor have been a problem for these lower aldehydes in terms of both improvement of working environment and improvement of living environment, and effective exclusion measures against them have been strongly demanded.
[0003]
Conventionally, as an adsorbent for lower aldehydes, activated carbon, activated clay, silica gel, activated alumina, clay mineral, and the like can be mentioned, and among them, activated carbon has been often used. However, these adsorbents, including activated carbon, have disadvantages in that their amount of adsorption to lower aldehydes such as formaldehyde and acetaldehyde is small and their lifetime is short. As an improvement measure, compounds having reactivity with lower aldehydes in the adsorbent, for example, organic compounds such as hydrazines, aliphatic amines, aromatic amines, ureas, ammonium salts, sulfites, There have been proposed those supporting inorganic compounds such as oxides and hydroxides of alkali metals or alkaline earth metals, iodine, bromine and compounds thereof with alkali metals or alkaline earth metals. Further, a catalyst in which a platinum group compound is supported on the adsorbent has been proposed. However, the adsorbent carrying an organic compound has problems with the stability, toxicity, odor, etc. of the organic compound, and in particular, those carrying aniline (Japanese Examined Patent Publication No. 60-54095) have aniline itself as a lower aldehyde. It has the disadvantage that it is unstable over time with respect to the adsorption of aldehydes, and has a problem in practical use because it is considered to be carcinogenic. Furthermore, the adsorbents of lower aldehydes carrying such organic compounds generally have the disadvantage of poor heat resistance. Adsorbents supporting inorganic compounds do not have sufficient adsorption rates for low concentrations of lower aldehydes. In addition, the catalyst loaded is expensive and has a low removal effect at room temperature. Thus, none of the conventional techniques is satisfactory for the removal of lower aldehydes.
[0004]
[Problems to be solved by the invention]
It is an object of the present invention to provide an adsorbent that efficiently adsorbs and removes lower aldehydes over a long period of time and exhibits excellent adsorption ability.
[0005]
[Means for Solving the Problems]
As a result of intensive studies in view of the above points, the present inventors have found that, in addition to morpholine, piperidine, or piperazine , at least one of phosphoric acid, sulfuric acid, citric acid , urea, and thiourea is supported on activated carbon. It has been found that aldehydes can be efficiently removed at room temperature over a long period of time, and a stable, safe and inexpensive adsorbent can be obtained, and the present invention has been completed based on this finding.
That is, the present invention
(1) morpholine, piperidine or piperazine, phosphoric acid, sulfuric acid, citric acid, and at least one selected from urea and thiourea and our sorbent lower aldehydes comprising brought supported on activated carbon (2) activated carbon The adsorbent for lower aldehydes according to the above (1), which is a honeycomb-like activated carbon,
It is.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The amount of morpholine, piperidine or piperazine added to the activated carbon used in the present invention is 1 to 50% by weight, preferably 5 to 20% by weight, based on the weight of the activated carbon anhydride.
Phosphoric acid used in the present invention, the addition amount sulfate, for the activated carbon of citric acid, 0.5 to 40 wt% per weight of activated carbon anhydride, preferably 1 to 20 wt%. In the present invention, phosphoric acid, sulfuric acid, instead of citric acid, or both, and a urea or thiourea is supported on activated carbon, the addition amount of the urea or thiourea activated carbon anhydride weight per 0.5 to 40 % By weight, preferably 1 to 20% by weight .
[0007]
Examples of the activated carbon raw material include plant raw materials such as wood powder and coconut shells, fossil raw materials such as anthracite, petroleum pitch, and coke, and various synthetic resin raw materials such as a phenol resin and a vinyl acetate resin. These activated carbon raw materials are carbonized and activated in, for example, a fixed bed, a moving bed, and a fluidized bed. Examples of activation include gas activation using water vapor, hydrogen chloride, carbon monoxide, carbon dioxide, oxygen, and chemical activation using alkali, acid, or zinc chloride. In the present invention, any of them is activated. But it can be used.
The activated carbon used in the present invention, BET specific surface area by nitrogen adsorption of liquid nitrogen temperature conditions usually 350~3,500m ² / g, preferably at the 500~3,000m ² / g.
In order to support activated carbon with morpholine, piperidine, piperazine , phosphoric acid, sulfuric acid, citric acid , urea, thiourea, the following methods can be mentioned depending on whether or not these substances are soluble in water. .
In the case of a substance that is soluble in water: a method in which the substance is dissolved in water in advance and the activated carbon is immersed in this aqueous solution and then filtered; a method in which the aqueous solution of the substance is sprayed or sprayed while stirring and mixing the activated carbon ; A method of granulating and molding activated carbon and an aqueous solution of the substance, and adding a binder as necessary.
[0008]
In the case of a substance insoluble in water: a method of physically mixing powdered activated carbon and the powdered substance. A method in which powdered activated carbon and the powdered substance are mixed in advance, and water and a binder are added to perform granulation and molding. A method in which a slurry is prepared in advance by adding the substance and binder to water, and the slurry is sprayed or sprayed on activated carbon and mixed.
Any of these substances may be supported on activated carbon first, or simultaneously. In the loading method, known binders are used as necessary. Examples thereof include carboxymethyl cellulose, polyvinyl alcohol, and arabic rubber, and the smaller the amount used, the better.
In the present invention, in addition to morpholine, piperidine or piperazine , an alkali metal or alkaline earth metal halide is further supported, so that the heat resistance of the adsorbent obtained can be improved.
[0009]
Examples of the alkali metal forming the halide include sodium and potassium, and examples of the alkaline earth metal include magnesium and calcium. Moreover, as a halogen, an iodine and a bromine are used preferably, for example. The amount of the halide added to the activated carbon is preferably 0.5 to 20% by weight, more preferably 1 to 10% by weight, based on the weight of the activated carbon anhydride. Such alkali metal and alkaline earth metal halides are supported on activated carbon by a method similar to the method for supporting morpholine, piperidine or piperazine . At this time, either morpholine, piperidine or piperazine and a halide may be supported first, or may be simultaneously supported. The shape of the adsorbent of the present invention is not particularly limited. For example, powder, granule, sphere, honeycomb or the like, or powder, granule, sphere, etc. are attached to nonwoven fabric, urethane foam, paper, processing board, etc. The shape can be raised.
The adsorbent thus obtained can be filled or contained as it is or in a suitable air-permeable container or adsorber so that it can be easily filled with lower aldehydes such as formaldehyde and acetaldehyde, in automobiles, coffee shops, conference rooms, workplaces or homes. Air purification can be achieved by placing it in the living room. When used in tobacco filters, harmful and irritating components such as formaldehyde and acetaldehyde in tobacco smoke can be efficiently removed.
[0010]
Among the adsorbent shapes described above, the honeycomb activated carbon is particularly preferable as the adsorbent shape of the present invention because it can significantly reduce the airflow resistance without significantly reducing the adsorption capacity over time. . Production of honeycomb activated carbon is known, and a method for producing honeycomb activated carbon is disclosed in, for example, Japanese Patent Publication No. 57-95816. The number of cells of the honeycomb activated carbon used in the present invention is about 10 to 1,500 cells / in ² , preferably about 50 to 1,000 cells / in ² . The thickness of the honeycomb-like activated carbon can be selected within a range in which the removal performance of lower aldehydes does not deteriorate, but is usually 5 to 200 mm, preferably about 7.5 to 150 mm. A plurality of these honeycomb-shaped carriers can be used by overlapping them as necessary. Typical examples of the lower aldehydes are those having 1 to 5 carbon atoms, particularly formaldehyde and acetaldehyde. On the other hand, there is a need for an adsorbent that is effective in combating odors. The adsorbent of the present invention can be expected to be effective for these aldehydes, and is particularly effective for the adsorption of formaldehyde and acetaldehyde.
[0011]
Examples The present invention will be described more specifically with reference to the following examples and test examples.
[Example 1]
Production of Adsorbents A to G (1) As activated carbon , honeycomb activated carbon having a BET specific surface area of 850 m ² / g, a cell number of 300 / in ² and a thickness of 20 mm was used. This honeycomb was cut into a diameter of 20 mm and used as an adsorbent A. The weight was 1.70 g.
(2) To the adsorbent A obtained in (1) above, 1.5 ml of an aqueous solution containing 170 mg of morpholine was sprayed uniformly and dried at 40 ° C. to produce Adsorbent B.
(3) To the adsorbent A obtained in (1) above, 1.5 ml of an aqueous solution containing 170 mg of morpholine and 64 mg of phosphoric acid was sprayed uniformly and dried at 40 ° C. to produce adsorbent C.
(4) To the adsorbent A obtained in (1) above, 1.5 ml of an aqueous solution containing 170 mg of morpholine and 96 mg of sulfuric acid was sprayed uniformly and dried at 40 ° C. to produce adsorbent D.
(5) To the adsorbent A obtained in (1) above, 1.5 ml of an aqueous solution containing 170 mg of morpholine and 96 mg of citric acid was evenly sprayed and dried at 40 ° C. to produce adsorbent E.
(6) To the adsorbent A obtained in the above (1), 1.5 ml of an aqueous solution containing 170 mg of morpholine and 59 mg of urea was uniformly sprayed and dried at 40 ° C. to produce adsorbent F.
(7) To the adsorbent A obtained in the above (1), 1.5 ml of an aqueous solution containing 170 mg of morpholine and 84 mg of thiourea was uniformly sprayed and dried at 40 ° C. to produce an adsorbent G.
[0012]
[Test Example 1]
5% breakthrough rate of formaldehyde-containing atmosphere 5 hour adsorption diameter A to G obtained in (1) to (7) above is stacked on each column on a column with an inner diameter of 20 mmφ, and each column contains 15 ppm formaldehyde Air (25 ° C., 70% relative humidity) was passed at 18.9 liters / minute, and the gas at the inlet and outlet of the column was analyzed by gas chromatography to determine the breakthrough rate of formaldehyde {(outlet concentration / inlet concentration) × The time (minutes) at which 100} is 5% was measured. The results are shown in [Table 1].
[0013]
[Table 1]
As is apparent from [Table 1], all of the adsorbents C to G of the present invention have a breakthrough rate of 5% reaching time of 200 minutes or more, and particularly, urea and thiourea-supported adsorbents F and G exceed 400 minutes. . In contrast, both the adsorbent A without chemicals and the adsorbent B supporting only morpholine have a breakthrough rate exceeding 5% before reaching 200 minutes. From this, it is clear that the adsorbent of the present invention exhibits formaldehyde adsorption ability over a long period of time.
[0014]
[Example 2]
Adsorbent H was granular coconut shell activated carbon having a BET specific surface area of 1200 m ² / g granulated to 4 to 6.5 mesh (according to the new JIS standard sieve mesh). Various chemicals were supported on the granular activated carbon H in the same manner as in Example 1 to produce adsorbents I, J, K, and L as shown in [Table 2]. In addition, in order to spray the aqueous solution uniformly, it was performed while rotating and mixing granular activated carbon.
[0015]
[Test Example 2]
Adsorbents H to L were packed in a column having an inner diameter of 40 mm to a layer height of 40 mm, and air containing 250 ppm acetaldehyde (25 ° C., relative humidity 70%) was passed through each column at 1.5 liters / minute. Measurement was made with gas detector tubes at the inlet and outlet of the column, and the time when the breakthrough rate of acetaldehyde {(outlet concentration / inlet concentration) × 100} exceeded 5% was examined.
[Table 2]
As is apparent from [Table 2], the adsorbents I to L using granular activated carbon carrying chemicals as the activated carbon of the present invention have a breakthrough rate of 5% reaching time of 2630 to 2850 hours. In contrast, in the case of the adsorbent H without a chemical, the breakthrough rate reached 5% in 390 minutes. From this, it is clear that the adsorbent carrying the chemical of the present invention exhibits acetaldehyde adsorption ability over a long period of time.
[0016]
【The invention's effect】
The adsorbent of the present invention can efficiently remove lower aldehydes at room temperature over a long period of time, and can be produced at low cost.

Claims (2)

An adsorbent for lower aldehydes, wherein morpholine, piperidine or piperazine and at least one selected from phosphoric acid, sulfuric acid, citric acid , urea and thiourea are supported on activated carbon . The adsorbent for lower aldehydes according to claim 1, wherein the activated carbon is honeycomb activated carbon.