JP4452935B1 - Lower aldehyde adsorbent and process for producing the same - Google Patents

Abstract

The present invention provides an excellent adsorbent for lower aldehydes that is thermally stable, safe for the environment, and capable of efficiently adsorbing and removing lower aldehydes over a long period of time. Objective.
The above-described problem is solved by heating a very small amount of an aqueous solution containing a predetermined amount of an alkali metal salt of urea and primary phosphoric acid and / or an alkali metal salt of acidic sulfuric acid to 40 to 95 ° C. and attaching the solution to activated carbon. Settled.
[Selection figure] None

Description

  The present invention relates to a very excellent adsorbent for lower aldehydes that is thermally stable, safe for the environment, and capable of efficiently adsorbing and removing lower aldehydes over a long period of time.

Lower aldehydes such as formaldehyde and acetaldehyde are harmful gases that emit unique irritating odors. Formaldehyde is said to have a carcinogenicity and an allowable concentration in air as low as 0.3 ppm. In addition, acetaldehyde and other C ₁ -C ₄ aliphatic lower aldehydes are designated as specific malodorous substances in Japan, and all of them are substances that have a very low olfactory threshold and cause odor pollution.
Formaldehyde generation sources include formaldehyde manufacturing plants, resin manufacturing plants made from urea, melamine, phenol, etc., processing plants for these resins, and manufacturing plants for building materials and furniture using these resins. Is mentioned. It is also contained in formaldehyde as a disinfectant, incomplete combustion exhaust gas of petroleum, and sidestream smoke of tobacco. Recently, formaldehyde generated from new building materials and furniture has become a problem even indoors.
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, harmful substances and odors have been seen as problems with these lower aldehydes from the viewpoint of improving the working environment and living environment. From this viewpoint, gas, especially lower aldehydes in the air are efficiently removed. There is a strong demand for the development of adsorbents.
Conventionally, as adsorbents for lower aldehydes, activated carbon, activated alumina, silica gel and the like have been used, and among them, activated carbon has been widely used. There are drawbacks in that the adsorption capacity for aldehydes is small and the lifetime is short.
As an improvement measure, a compound that reacts with the lower aldehydes, for example, an organic compound such as urea, aliphatic amines, aromatic amines, etc. supported on the adsorbent is proposed.

For example, an adsorbent in which urea and sodium carbonate are supported on a porous inorganic sintered body (Patent Document 1), an adsorbent in which urea and ammonium sulfate, urea and sodium hydroxide are supported on activated carbon (Patent Document 2), Adsorbents (Patent Document 3) in which urea and calcium chloride, urea and magnesium chloride are supported on a porous material have been devised.
However, the adsorption performance of these lower aldehyde adsorbents is not always satisfactory.
In addition, in the Japanese Patent Application No. 2008-170621, the inventor impregnated activated carbon with urea, carbonic acid, phosphoric acid, sulfuric acid, and an alkali metal salt of a C ₁ -C ₆ carboxylic acid at a temperature of 45 to 195 ° C. Although an adsorbent for lower aldehydes obtained by heating and drying has been proposed, the removal performance of lower aldehydes, particularly acetaldehyde, cannot be said to be sufficient.

JP-A-62-286464 JP-A-9-313828 JP-A-11-285633

  The present invention provides a very excellent adsorbent for lower aldehydes that is thermally stable, safe for the environment, and capable of efficiently adsorbing and removing lower aldehydes over a long period of time. It is aimed.

The present inventor has intensively studied in view of the above points, and contains 150 to 300 mg of urea (a) and 10 to 80 mg of alkali metal salt of primary phosphoric acid and / or alkali metal salt of acidic sulfuric acid (b). 30 to 95 ° C., preferably by contacting an aqueous solution of 300~1000μL was warmed to 40 to 95 ° C. in the activated carbon 1g, adsorbent obtained by impregnating the addition of chemicals is very long-term lower aldehydes to It has been found that an adsorbent that can be efficiently adsorbed and removed can be obtained.
By heating the aqueous solution to 30 to 95 ° C., it is possible to easily dissolve a predetermined amount of urea and the alkali metal salt required for attachment to a very small amount of the aqueous solution. By bringing this aqueous solution into contact with activated carbon, a predetermined amount of urea and the above alkali metal salt can be instantly attached to the activated carbon surface, and the lower aldehydes are adsorbed very well without being dried after the addition.・ It was found that the adsorbent can be removed.
In the prior art, in order to prevent chemical adhesion, etc., use a large amount of aqueous solution in which chemical is dissolved in porous adsorbent such as activated carbon, soak the porous adsorbent in this aqueous solution, filter it, etc. After the solid-liquid separation by this method, the product was dried for a long time at a temperature of about 100 ° C., and the finished product of the aldehyde adsorbent was obtained only after removing the water adhering to the adsorbent. On the other hand, in the present invention, since only a very small amount of a chemical-containing aqueous solution in which a large amount of adsorbing chemical is dissolved to near the saturation concentration is used, even the adsorbent immediately after adsorbing the chemical on activated carbon adsorbs the lower aldehydes very efficiently.・ We found that it can be removed. This is considered to be due to the fact that the adsorbing chemical is supported at a higher density than the conventional product on the adsorbent surface in contact with the gas containing the lower aldehyde.
Moreover, lower aldehydes can be better adsorbed and removed by previously oxidizing the activated carbon.

As the activated carbon used in the present invention, any activated carbon may be used as long as it is activated by a normal method using charcoal, coke, coal, coconut shell, resin, or the like as a raw material. The shape may be any shape such as powder, crushed, columnar, spherical, honeycomb, or fiber. The specific surface area of the activated carbons include, ^{50 m} 2 / g or more, preferably 100~2500m ² / g. In the case of activated carbon such as honeycomb and fiber, a predetermined amount of chemical can be contained, and a predetermined amount of heated aqueous solution can be attached to the predetermined amount of activated carbon using a spray or the like.
By pre-oxidizing activated carbon, the adsorption performance of lower aldehydes is significantly improved. Examples of the method for oxidizing activated carbon include nitric acid, nitrogen oxide (NOx), sulfuric acid, sulfur oxide (SOx), sulfur trioxide, chlorine dioxide, hydrogen peroxide, ozone, oxygen-containing gas (for example, air, combustion) For example, oxidation may be performed in a liquid phase or a gas phase with an oxidizing agent such as exhaust gas. In the case of NOx, SOx, etc., the activated carbon may be oxidized by a method such as repeated adsorption and desorption of NOx and SOx-containing gas on the activated carbon. In addition, when the oxidizing power for activated carbon is weak, such as gas phase oxidation with an oxygen-containing gas, the temperature is higher than room temperature, for example, 200 ° C. or higher, preferably 200 to 800 ° C., depending on the oxygen concentration in the gas. More preferably, it is efficient to carry out at a temperature of 250 to 600 ° C. In addition, spent activated carbon used for many years at ozone treatment plants in water treatment plants in large cities has produced a large amount of oxygen-containing groups on its surface due to ozone oxidation in the liquid phase. Such activated carbon can be effectively used in the present invention.

Such an oxidation treatment produces oxygen-containing groups on the activated carbon surface. In the oxidation treatment of the present invention, the amount of these oxidizing agents used for activated carbon depends on the treatment method and oxidation conditions (for example, treatment temperature, time, etc.), but is usually 10 mg or more in terms of oxygen atom per gram of activated carbon. The amount is preferably 20 mg or more, and more preferably 30 to 2000 mg.
By these oxidation treatments, for example, oxygen-containing groups such as a carbonyl group, a carboxyl group, and a phenolic hydroxyl group are generated on the activated carbon surface. This surface oxygen-containing group is 1% by weight or more, preferably 2% by weight or more, more preferably 3 to 80% by weight of the activated carbon as oxygen atoms.

In the present invention, the alkali metal salt of primary phosphoric acid and the alkali metal salt of acidic sulfuric acid used include lithium salt, sodium salt, potassium salt, rubidium salt, and cesium salt. It is more preferable because it is stable and safe for the environment. Accordingly, examples of the salt include monobasic sodium phosphate, primary potassium phosphate, acidic sodium sulfate, and acidic potassium sulfate. In addition, when the alkali metal salt of urea and primary phosphoric acid and the alkali metal salt of acidic sulfuric acid are dissolved in water, it is easier to dissolve urea and these alkali metal salts by adding an acid such as phosphoric acid or sulfuric acid. At the same time, improving the adsorption performance of the lower aldehyde, particularly the initial adsorption performance, is one of the major features of the present invention. The amount of phosphoric acid and sulfuric acid to be added is 0.1 to 20 mol, preferably 0.2 to 15 and more preferably 0.2 to 10 mol with respect to 1 mol of these alkali metal salts.
Further, in the present invention, neutralization reaction between sulfuric acid and an alkaline alkali metal compound as an alkali metal salt of phosphoric acid and an alkaline alkali metal compound, and an alkaline metal salt of acidic sulfuric acid as an alkali metal salt of primary phosphoric acid. Another major feature is the use of the product. Here, the alkaline alkali metal compound is, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like. When using a neutralization reaction product as these alkali metal salts, the theoretical amount of the adsorbent produced by using phosphoric acid and sulfuric acid in excess of the theoretical amount necessary for the neutralization reaction should be used. It has also been found that the adsorption performance of lower aldehydes, especially the initial adsorption performance, is improved compared to the case where it was present. The excessive amount of phosphoric acid and sulfuric acid is 1.1 to 20 times the theoretical amount, preferably 1.2 to 15 times, more preferably 1.2 to 10 times.
Further, when a neutralization reaction product is used as these alkali metal salts, it is more desirable to first add a predetermined amount of urea to the aqueous solution after completion of the neutralization reaction and attach it to activated carbon. By doing in this way, since the temperature of aqueous solution rises with the heat of neutralization, warming of the aqueous solution for attachment becomes easier.

  The lower aldehyde adsorbent of the present invention is an aqueous solution containing urea (a) and an alkali metal salt of primary phosphoric acid and / or an alkali metal salt of acidic sulfuric acid (b) heated to 30 to 95 ° C. and attached to activated carbon. Is easily obtained. The impregnation can be performed by spraying and spraying the aqueous solution on activated carbon, for example, and stirring as necessary. Warming of an aqueous solution containing an alkali metal salt of urea and primary phosphoric acid and / or an alkali metal salt of acidic sulfuric acid can be performed directly or indirectly by a conventional method. The time for heating the aqueous solution containing the alkali metal salt of urea and primary phosphoric acid and / or the alkali metal salt of acidic sulfuric acid to 30 to 95 ° C. is not particularly limited. In short, it is only necessary that the temperature of the aqueous solution containing the alkali metal salt of urea and primary phosphoric acid and / or the alkali metal salt of acidic sulfuric acid becomes a predetermined temperature and becomes a uniform solution. If the temperature of the aqueous solution containing the alkali metal salt of urea and primary phosphoric acid and / or the alkali metal salt of acidic sulfuric acid exceeds 95 ° C., these chemicals are altered and a large amount of water vapor is generated, which is not preferable. On the other hand, when the water temperature is less than 30 ° C., it is difficult to dissolve the amount of urea and alkali metal salt necessary for the addition with a very small amount of aqueous solution, and the lower aldehyde adsorbing performance of the adsorbent after the addition is decreased, which is preferable. Absent.

The lower aldehydes to be removed in the present invention refer to aldehydes having 6 or less carbon atoms and a boiling point of 100 ° C. or less, such as formaldehyde, acetaldehyde, propionaldehyde, acrolein, and 3-methyl-butyraldehyde. Formaldehyde and acetaldehyde.
In the present invention, aldehydes can be efficiently removed by allowing the aldehyde adsorbent obtained as described above to exist in a space or in an apparatus. In the case where the aldehyde adsorbent is present in the space, for example, the aldehyde adsorbent may be formed into a sheet shape, included in a building material, or a method that is usually performed. Moreover, when it exists in an apparatus etc., the method etc. which fill a tower, a container, etc., and ventilate the gas containing aldehydes to these are considered.

  The aldehyde adsorbent of the present invention is an odorless and chemically and thermally stable solid composition of urea and primary phosphoric acid alkali metal salt and / or acidic sulfuric acid near the room temperature where it is used. Since the alkali metal salt is impregnated with activated carbon, it is thermally stable, safe for the environment, and can efficiently adsorb and remove lower aldehydes over a long period of time, compared to conventional lower aldehyde adsorbents. It is an excellent adsorbent for lower aldehydes.

  The present invention will be specifically described with reference to the following examples.

As shown in Table 1, 150 to 2500 μL of an aqueous solution containing 300 mg of urea and 40 mg of primary potassium phosphate is heated to 80 ° C. per 1 g of 8-32 mesh bituminous coal-based activated carbon A (BET specific surface area of 1150 m ² / g). Each sample was prepared by being attached to and left in the atmosphere for 12 hours.
200 mg of each of these samples was weighed into a 3 L tetrabag and filled with air. A predetermined amount of acetaldehyde aqueous solution was injected into each tetrabag to adjust the acetaldehyde concentration (C ₀ ) in each tetrabag to 650 ppm. The acetaldehyde concentration (C) in each tetrabag after 24 hours was measured. The values obtained by the following formula as acetaldehyde removal performance are shown in Table 1.
Acetaldehyde removal performance = (1-C / C ₀ ) × 100 (%)

As is apparent from Table 1, when the amount of aqueous solution containing urea and primary potassium phosphate is in the range of 300 to 1000 μL per gram of activated carbon, the acetaldehyde removal performance is 90% or more, but when it is 1800 μL or more, the performance deteriorates. . In the prior art, the amount of the aqueous solution containing chemicals is usually 1100 μL or more per gram of activated carbon in order to prevent adhesion.

Each sample which 300 microliters aqueous solution which contains 300 mg of urea and 40 mg of monobasic potassium phosphate with respect to 1 g of activated carbon A of Example 1 at 20-95 degreeC was attached as shown in Table 2, and was left to stand in air | atmosphere for 12 hours. Was prepared.
Table 2 shows the results of measuring the acetaldehyde removal performance of each of these 200 mg samples in the same manner as in Example 1.

From Table 2, it is clear that the temperature of the aqueous solution for attachment containing chemicals is preferably in the range of 30 to 95 ° C. In the prior art, the temperature of the aqueous solution for attachment is usually room temperature (around 25 ° C.).

Each sample which was heated at 80 ° C. for 300 μL of an aqueous solution containing 300 mg of urea and 40 mg of various inorganic salts with respect to 1 g of activated carbon A of Example 1 and attached as shown in Table 3, and left in the atmosphere for 12 hours. Was prepared.
Table 3 shows the results of measuring the acetaldehyde removal performance of each of these 200 mg samples in the same manner as in Example 1.

From Table 3, among the inorganic chemicals combined with urea, the chemicals of the present invention (primary sodium phosphate, acidic sodium sulfate, acidic potassium sulfate) are all very good at 100% acetaldehyde removal performance. On the other hand, those of the prior art other than these chemicals have a very bad acetaldehyde removal performance of 55 to 85%.

Sample No. 1 of Example 1 2 and Sample 3 of Example 3. 50 mg of each sample of 15-23 was weighed into a 3 L tetra bag and filled with air. A predetermined amount of formaldehyde aqueous solution was injected into each tetrabag, and the formaldehyde concentration (C ₀ ) in each tetrabag was set to 300 ppm. The formaldehyde concentration (C) in each tetrabag after 24 hours was measured. Table 4 shows the value obtained by the following formula as the formaldehyde removal performance.
Formaldehyde removal performance = (1-C / C ₀ ) × 100 (%)

This result is almost the same as the result shown in Table 3.

300 g of urea and the amount of primary potassium phosphate as shown in Table 5 are added to 300 μL of water per 1 g of 8-32 mesh coconut shell activated carbon B (BET specific surface area of 1200 m ² / g) and heated to 80 ° C. Each sample was prepared by being warmed and impregnated and allowed to stand in the atmosphere for 12 hours.
Table 5 shows the results of measuring the acetaldehyde removal performance of each of these 200 mg samples in the same manner as in Example 1.

From this experimental result, it is understood that when the urea addition amount is constant at 300 mg / g, the range of the first potassium phosphate addition amount is 10 to 150 mg. When the amount of primary potassium phosphate added is 300 mg / g or more, the activated carbon surface is covered with chemicals, and the acetaldehyde adsorption / removal performance is lowered.

  In Example 5, acidic potassium sulfate was used instead of primary potassium phosphate. The results are shown in Table 6.

The acidic potassium sulfate has the same result as the primary potassium phosphate shown in Table 5.

300 g of an aqueous solution containing 300 mg of urea and 40 mg of monobasic sodium phosphate was added to 1 g of activated carbon A of Example 1 at 80 ° C. and attached. After the application, samples were prepared that were allowed to stand in air for 5 minutes, 30 minutes, 12 hours, and 1 week.
Table 7 shows the results of measuring the acetaldehyde removal performance of each of these 200 mg samples in the same manner as in Example 1.

From Table 7, it is clear that the adsorbent immediately after chemical addition exhibits excellent acetaldehyde removal performance. In the prior art, a porous adsorbent such as activated carbon is immersed in a large amount of a chemical-containing aqueous solution. It is in a state where even the weighing of the sample for the adsorption test cannot be performed.

By filling each 30g of activated carbon A Example 1 in a quartz glass tube 55Mmfai, respectively 250,400,500, and _O 2 _-10.0vol% content of _{N 2} gas linear flow rate 5cm at each temperature of 600 ° C. After being circulated for 20 minutes at / second, the mixture was cooled to room temperature in N ₂ gas to obtain activated carbons C, D, E, and F.
For the activated carbons C, D, E, and F subjected to oxidation treatment, the surface oxygen amounts attributable to the surface oxides or oxygen-containing groups measured by the following method were 5.5% by weight, 8.9% by weight, and 12. 3% and 16.1% by weight. The oxygen content of the activated carbon A that was not oxidized was 0.7% by weight.
"Measurement method of surface oxygen content of activated carbon"
3 g of sample activated carbon was placed in a quartz column having a diameter of 20 mm and a length of 1,000 mm, and the sample was fixed on quartz glass wool that had been sufficiently dried before and after the sample and set in an electric annular furnace. In addition, the quartz column has a hole for introducing nitrogen and a hole for discharging nitrogen by capping the front and back with rubber stoppers. While flowing nitrogen through the quartz column at a flow rate of 100 ml / min, the temperature was raised to 100 ° C., and then the outlet gas was connected to a tetra-buck and heated to 900 ° C. at a rate of 400 ° C./hour. After reaching 900 ° C., hold at 900 ° C. for another 30 minutes, then remove the tetraback, measure the amount of gas collected, and add the total concentration of CO and CO ₂ in the collected gas with a methane converter. The amount of surface oxygen was calculated by gas chromatography with a FID detector.
In 400 μL of water, 250 mg of urea and 60 mg of monobasic potassium phosphate are added, heated to 80 ° C. to completely dissolve them, and uniformly attached to 1 g of each of activated carbon A, C, D, E and F. Left in it for 12 hours.
100 mg of each of these samples was weighed into a 3 L tetrabag and filled with air. A predetermined amount of acetaldehyde aqueous solution was injected into each tetrabag to adjust the acetaldehyde concentration (C ₀ ) in each tetrabag to 650 ppm. The acetaldehyde concentration (C) in each tetrabag after 24 hours was measured. Table 8 shows the values obtained by the following formula as acetaldehyde removal performance.
Acetaldehyde removal performance = (1-C / C ₀ ) × 100 (%)

As is apparent from Table 8, it can be seen that the removal performance of acetaldehyde is remarkably improved by subjecting the activated carbon to oxygen oxidation treatment.

100 ml of activated carbon B of Example 5 was placed in an acrylic column having an inner diameter of 94 mmφ in a stainless steel wire mesh container to form an activated carbon packed layer. Air containing about 180 ppm of ozone was circulated through the activated carbon layer at a flow rate of 5 L / min for 25 days to obtain ozone-oxidized activated carbon G in the gas phase. The surface oxygen amounts of the activated carbons B and G were 0.5% by weight and 12.5% by weight, respectively.
For activated carbon B and G, put 250 mg of urea and 30 mg of monobasic sodium phosphate in 400 μL of water, heat to 80 ° C. to completely dissolve them, and uniformly impregnate each 1 g of activated carbon B and G. Left in it for 12 hours.
Table 9 shows the results of measuring acetaldehyde removal performance of 100 mg of each sample thus obtained in the same manner as in Example 8.

As shown in Table 9, acetaldehyde removal performance is improved by ozone oxidation of activated carbon.

A 500 mL beaker was charged with 100 mL of 5 wt% hydrogen peroxide and heated to 80 ° C in an 80 ° C water bath. 10 g of the activated carbon A of Example 1 was put in this hydrogen peroxide solution and oxidized for 30 minutes while stirring. The oxidized activated carbon was filtered and dried at 100 ° C. The surface oxygen amount of the activated carbon H subjected to the oxidation treatment was 8.5% by weight.
For activated carbon A and H, 300 mg of urea and 40 mg of acidic potassium sulfate were added to 400 μL of water, heated to 80 ° C. to completely dissolve them, and uniformly attached to 1 g of each of activated carbon A and H. And left for 12 hours.
Table 10 shows the results of measuring the acetaldehyde removal performance in the same manner as in Example 8 for 100 mg of each sample thus obtained.

From the results shown in Table 10, it is clear that the effect of the hydrogen peroxide oxidation treatment is exhibited.

The activated carbon A of Example 1 was used for 3 years in an ozone process advanced water treatment plant, and the activated carbon which was ozone-oxidized in the liquid phase was dried at 110 ° C. for 1 hour. The surface oxygen content of this used activated carbon I was 25.6% by weight.
About activated carbon A and activated carbon I, urea 300 mg and acidic sodium sulfate 40 mg were put in 400 μL of water, heated to 80 ° C. to completely dissolve them, and uniformly attached to each 1 g of activated carbon A and activated carbon I. It was left in the atmosphere for 12 hours.
Table 11 shows the results of measuring the acetaldehyde removal performance of 100 mg of each sample thus obtained in the same manner as in Example 8.

From Table 11, it is clear that the acetaldehyde removal performance is improved by applying the method of the present invention to activated carbon that has been subjected to ozone oxidation for a long time in an advanced water purification plant.

In 3,000 μL of water, 227 μL of 85% phosphoric acid (containing 324 mg as H ₃ PO ₄ ) and 185 mg of caustic potassium were added and stirred at room temperature for 5 minutes to complete the neutralization reaction, thereby producing about 450 mg of primary potassium phosphate. After adding 3000 mg of urea to this aqueous solution and heating to 80 ° C., sample NO44 was prepared by attaching to 10 g of activated carbon A of Example 1 and leaving it in the atmosphere for 12 hours.
About 200 mg of this sample, the acetaldehyde removal performance was measured by the same method as in Example 1. As a result, the acetaldehyde removal performance was 100%. This sample is a sample No. 1 of Example 1. Similar to 2 (one obtained by adding 300 mg of urea and 40 mg of primary potassium phosphate per gram of activated carbon A), it exhibited very excellent acetaldehyde removal performance.

In 2000 μL of water, 1100 μL of 3 mol / L sulfuric acid (containing 324 mg as H ₂ SO ₄ ) and 228 mg of potassium carbonate were added and stirred at room temperature for 5 minutes to complete the neutralization reaction, thereby producing about 450 mg of acidic potassium sulfate. . After adding 3000 mg of urea to this aqueous solution and heating to 80 ° C., it was attached to 10 g of activated carbon A of Example 1 and left in the atmosphere for 12 hours. 45 was prepared.
About 200 mg of this sample, the acetaldehyde removal performance was measured by the same method as in Example 1. As a result, the acetaldehyde removal performance was 100%. This sample is the sample No. 3 of Example 3. As in 17 (300 mg of urea and 40 mg of acidic potassium sulfate per 1 g of activated carbon A), very good acetaldehyde removal performance was exhibited.

In Example 12, using 85% phosphoric acid 454μL instead of 85% phosphoric acid 227μL _(324mg containing as H 3 PO _{4) (648mg} containing as H 3 PO _4), samples were prepared in the same manner as in Example 12 method No . 46 was created.
Sample No. 12 in Example 12 44 and sample no. Each 46 mg of 100 was weighed into a 3 L tetrabag and filled with air. A predetermined amount of acetaldehyde aqueous solution was injected into each tetrabag to adjust the acetaldehyde concentration (C ₀ ) in each tetrabag to 650 ppm. The acetaldehyde concentration (C) in each tetrabag after 3 hours and 24 hours was measured. Table 3 shows the 3-hour value and 24-hour value obtained by the following formula as the acetaldehyde removal performance.
Acetaldehyde removal performance = (1-C / C ₀ ) × 100 (%)

No. No. 46 contains about 324 mg per gram of activated carbon as free phosphoric acid, so No. 46 containing no free phosphoric acid. Compared to 44, the performance of the 3-hour value is very good as well as the 24-hour value.

2200 μL of 3 mol / L sulfuric acid (containing 648 mg as H ₂ SO ₄ ) and 228 mg of potassium carbonate were added to 1000 μL of water and stirred at room temperature for 5 minutes to complete the neutralization reaction, thereby producing about 450 mg of acidic potassium sulfate. . This aqueous solution contained about 324 mg of free sulfuric acid. After adding 3000 mg of urea to this aqueous solution and heating to 80 ° C., it was attached to 10 g of activated carbon A of Example 1 and left in the atmosphere for 12 hours. 47 was prepared.
Sample No. 13 in Example 13 45 and sample no. 47 mg of each 100 mg was weighed into a 3 L tetrabag and filled with air. A predetermined amount of acetaldehyde aqueous solution was injected into each tetrabag to adjust the acetaldehyde concentration (C ₀ ) in each tetrabag to 650 ppm. The acetaldehyde concentration (C) in each tetrabag after 3 hours and 24 hours was measured. Table 13 shows the 3-hour value and 24-hour value obtained by the following formula as the acetaldehyde removal performance.
Acetaldehyde removal performance = (1-C / C ₀ ) × 100 (%)

No. No. 47 contains about 324 mg / g of activated carbon as free sulfuric acid and no free phosphoric acid. Compared to 45, it is evident that the performance of the 3-hour value as well as the 24-hour value is significantly improved.

  300 μL of an aqueous solution containing 300 mg of urea, 41 mg (about 0.3 mmol) of primary potassium phosphate and the amount of sulfuric acid as shown in Table 14 was prepared. This aqueous solution was heated to 80 ° C., attached to 1 g of the activated carbon A of Example 1, and 100 mg of each sample left in the atmosphere for 12 hours in the same manner as in Example 15 to remove acetaldehyde (3 Time values and 24 hour values) were measured and the results are shown in Table 14.

Figures in parentheses: molar ratio of sulfuric acid / monobasic potassium phosphate

From Table 14, it can be seen that the addition of 0.2 to 10 mmol of sulfuric acid to 1 mmol of primary potassium phosphate dramatically improves the acetaldehyde removal performance in particular for 3 hours.

  The adsorbent for lower aldehydes according to the present invention can be used in factories, medical facilities, sewage treatment plants, garbage incinerators, smoking rooms, etc. where aldehydes such as formaldehyde and acetaldehyde are generated. Adsorbs and removes well.

Claims (8)

A 300 to 1000 μL aqueous solution containing 150 to 300 mg of urea (a) and 10 to 80 mg of an alkali metal salt of primary phosphoric acid and / or an alkali metal salt of acidic sulfuric acid (b) and heated to 30 to 95 ° C. lower aldehydes adsorbent obtained by Rukoto is affixed in addition to the activated charcoal 1g. 150 to 300 mg of urea (a), alkali metal salt of primary phosphoric acid and / or 10 to 80 mg of alkali metal salt of acidic sulfuric acid (b) and 1 mol of the alkali metal salt (b) phosphoric acid and / or sulfuric acid (c ) and contains 0.2 to 10 mol, and lower aldehydes adsorbent obtained by Rukoto is impregnated with an aqueous solution of 300~1000μL warmed to 30 to 95 ° C. in addition to the activated charcoal 1g.   The lower aldehyde adsorbent according to claim 1 or 2, wherein the activated carbon is activated carbon previously oxidized.   The lower aldehyde adsorbent according to claim 1 or 2, wherein the alkali metal salt of primary phosphoric acid is a neutralization reaction product of phosphoric acid and an alkaline alkali metal compound.   The lower aldehyde adsorbent according to claim 1 or 2, wherein the alkali metal salt of acidic sulfuric acid is a neutralization reaction product of sulfuric acid and an alkaline alkali metal compound.   The lower aldehyde adsorbent according to claim 4, wherein phosphoric acid is used in an amount of 1.2 to 10 times the theoretical amount when the alkali metal salt of primary phosphoric acid is produced by a neutralization reaction.   The lower aldehyde adsorbent according to claim 5, wherein sulfuric acid is used in an amount of 1.2 to 10 times the theoretical amount when the alkali metal salt of acidic sulfuric acid is produced by a neutralization reaction.   Heated to 30-95 ° C. containing 150-300 mg of urea (a) and alkali metal salt of primary phosphoric acid and / or alkali metal salt of acidic sulfuric acid (b) 10-80 mg per 1 g of activated carbon A method for producing a lower aldehyde adsorbent in which 1000 μL of an aqueous solution is contacted.