JP4759757B2 - Aldehyde adsorbent and adsorption filter - Google Patents

Description

  The present invention relates to an adsorbent and an adsorption filter used for adsorbing and removing aldehydes such as formaldehyde and acetaldehyde in the air.

Aldehydes in the air are pollutants that adversely affect health. Formaldehyde is a chemical building material, acetaldehyde is a malodorous gas mainly produced by cigarettes and automobile exhaust gas, and indoor air pollution is a problem. Removal of these aldehydes is essential for people to live comfortably.
In adsorbents for removing aldehydes in the air, not only the physical adsorption action of adsorbents such as activated carbon, but also the adsorption performance is improved by chemically modifying the adsorbent surface. It is.
As a method for improving such adsorption performance, a method of supporting a basic compound such as an amino group-containing compound on a carrier has been developed (see Patent Documents 1 to 6). These methods are methods using an amino group-containing organosilicon compound such as 3-aminopropyltrimethoxysilane (APTMS) or a hydroxylamine such as hydroxylammonium phosphate (HAP) as a basic compound, This utilizes a Schiff base reaction between an amino group that modifies the carrier surface and a CHO group of an aldehyde.
Although the adsorption performance is improved in these methods, it is desired to further increase the adsorption amount and improve the sustainability of the activity.

Japanese Patent No. 3489136 Japanese Patent No. 3430955 Japanese Patent No. 3455000 JP-A-8-257346 JP 2006-312164 A JP 2002-282683 A

  An object of the present invention is to improve the amount of adsorption and sustainability in an adsorbent and a filter used for adsorbing and removing aldehydes such as formaldehyde and acetaldehyde.

The present inventors diligently studied a method using a carrier surface-modified with an amino group-containing organosilicon compound such as 3-aminopropyltrimethoxysilane (APTMS) as a method for adsorbing and removing aldehydes using a Schiff base reaction. I have done it. As a result, it has been found that there is a quantitative limit to bind the amino group-containing organosilicon compound as it is to the support surface, and the support is first treated with alkali to increase the number of silanol groups on the surface before binding APTMS and the like. As a result, it was found that the adsorption amount of aldehydes can be increased, and a patent application was filed (Patent Document 5).
In addition, the present inventors have developed a method using hydroxylammonium phosphate (HAP) as a surface modifier of the carrier (Patent Document 6). However, when the development was further continued, it was found that HAP can improve the adsorption amount as compared with the case of using APTMS, but it has been found that there is a problem that deterioration due to heat is quick. Therefore, as a result of intensive studies on an adsorbent that can be used for a long time without causing deterioration due to heat, it is possible to stabilize HAP by adding a polymer having a functional group that interacts with the amino group of HAP, such as polystyrene sulfonic acid. The headline, the present invention has been reached.

That is, the present invention relates to the following adsorbent.
(1) An aldehyde adsorbent characterized in that a hydroxylamine and a polymer having a functional group that interacts with an amino group of the hydroxylamine are attached to a carrier.
(2) The aldehyde adsorbent according to (1), wherein the hydroxylamine is one or more of hydroxylamine or an addition salt thereof.
(3) The aldehyde adsorbent according to (2) above, wherein the addition salt of hydroxylamine is hydroxylamine phosphate, hydroxylamine hydrochloride, hydroxylamine nitrate, hydroxylamine oxalate or hydroxylamine sulfate.
(4) The aldehyde adsorbent according to (1) above, wherein the hydroxylamine is hydroxylamine phosphate.
(5) The aldehyde adsorbent according to any one of (1) to (4), wherein the polymer chain of the polymer having a functional group that interacts with an amino group of hydroxylamines is polystyrene.
(6) The aldehyde adsorbent according to any one of (1) to (5), wherein the functional group that interacts with the amino group of hydroxylamines is a sulfone group.
(7) The aldehyde adsorbent according to any one of (1) to (6), wherein the polymer having a functional group that interacts with an amino group of hydroxylamines is polystyrenesulfonic acid.
(8) The aldehyde adsorbent according to any one of (1) to (7), wherein the carrier is activated carbon or an inorganic oxide.
(9) The aldehyde adsorbent according to (8), wherein the carrier is alumina.
(10) The aldehyde adsorbent according to any one of (1) to (9), wherein the aldehyde is acetaldehyde.

  The present invention also relates to a method for producing the adsorbent and a filter in which the adsorbent is held on a support.

  According to the present invention, in the adsorbent and the filter used for adsorbing and removing aldehydes such as formaldehyde and acetaldehyde, the adsorption amount of aldehydes can be improved and the heat resistance can be improved and the life can be increased.

The present invention will be specifically described below, but the present invention is not limited thereto.
The aldehyde adsorbent and filter of the present invention can be used to clean air containing aldehydes, particularly indoor air. In particular, the gas adsorbent and the filter of the present invention are effective for use in cleaning the air inside the automobile.

In the present invention, aldehydes are compounds having an aldehyde group in the molecule, and are represented by formaldehyde and acetaldehyde.
Formaldehyde is mainly a new building material, and acetaldehyde is the main source of generation of cigarettes and automobile exhaust gas.

The hydroxylamines used in the present invention refer to hydroxylamine and its addition salt.
Hydroxylamine addition salts include hydroxylamine phosphate (NH ₃ OH) PO ₄ ; hydroxylamine sulfate (NH ₃ OH) SO ₄ ; hydroxylamine nitrate (NH ₃ OH) NO ₃ ; hydroxylamine oxalate (NH ₃ OH) ₂ C ₂ O ₄ ; hydroxylamine hydrochloride (NH ₃ OH) Cl may be mentioned, but hydroxylamine phosphate is most preferable from the viewpoint of the amount of adsorption.

  The carrier that can be used in the present invention is activated carbon or inorganic oxides such as silica, alumina, titania, zirconia, and zeolite, cloths, glasses, resins, paper, woods and the like. As fabrics, natural fibers or synthetic fibers represented by cotton, acrylic fiber, polyester fiber, wool, cellulose fiber, polyurethane, polyvinyl alcohol fiber, vinylon; as glass, glass beads, glass fiber; as resin, Styrol resin, ABS resin, polycarbonate resin, POM resin (polyacetal resin), acrylic resin, vinyl chloride resin, phenol resin, urethane resin, epoxy resin, polyethylene resin, polypropylene resin, polyvinyl acetate, polyvinylidene chloride, polymethyl methacrylate And synthetic resins represented by urea resin, melamine resin, alkyd resin, ion exchange resin, polyamide resin, and polyimide resin. Of these, alumina is particularly preferable. When the shape of the carrier is activated carbon or an inorganic oxide, a powder or a granular material is preferable.

The polymer having a functional group that interacts with the amino group of hydroxylamines in the present invention is a polymer that can interact with the amino group to suppress decomposition of hydroxylamine. The interaction may be an ionic interaction or a physical interaction such as van der Waals force.
Examples of the functional group of the polymer having a functional group that interacts with the amino group of hydroxylamine include sulfone group, hydroxy group, peroxy, ketone, aldehyde group, acetal, hemiacetal, carboxyl group and its acid anhydride, acid halide , Acid hydrazone, acid azide, peracid, thioester, nitrate ester, amide, thioamide, imide, amidine, cyano, oxime, thiol, sulfide, urea, guanidine, thiourea, isonitrile, cumulene, ketene, diimide, isocyanate, thioisocyanate, Examples include a carbonyl group, an amino group, an imino group, a cyano group, an azo group, an azide group, a thiol group, a nitro group, an ether bond, an ester bond, an amide bond, and a urethane bond, and a sulfone group is most preferable.
Polymer chains include polyolefin, polystyrene, polyvinyl, polyacryl, polyhaloolefin, polydiene, polyether, polysulfide, polyester, polyamide, polyurethane, polyurea, polyimide, polyanhydride, polycarbonate, polyimine, polysiloxane, poly Examples include phosphazenes, polyketones, polysulfones, polyphenylenes, polysaccharides, and polypeptides, with polystyrene being most preferred.
Regarding a polymer having a functional group that interacts with the amino group of hydroxylamines, as a polymer in which the functional group is a sulfone group and the polymer chain is polystyrene, polystyrene (polystyrenesulfonic acid) Poly (4-styrenesulfonic acid) (PSS), poly-4- An example is propoxysulfonylstyrene poly [4- (propoxysulfonyl) styrene]. In addition, as a copolymer partially containing polystyrene sulfonic acid, poly [vinylbenzene-co- (4-vinylbenzenesulfonic acid)] poly [vinylbenzene-co- (4-vinylbenzenesulfonic acid)], poly [pyrrole-co- ( 4-sulfostyrene)] poly [pyrrole-co- (4-sulfostyrene)], poly [styrene-co- (4-vinylbenzenesulfonic acid) -co- (4-vinylpyridine) -co- (ethyl acrylate)] poly [styrene-co- (4-vinylbenzenesulfonic acid) -co- (4-vinylpyridine) -co- (ethyl acrylate)], poly [ethene-co- (4-vinylbenzenesulfonic acid)], partially sulfonated poly [styrene- Co- (p-divinylbenzene)] partially sulfonated poly [styrene-co- (p-divinylbenzene)], sulfonated, hydrogenated poly (styrene-block-butadiene), poly ( 1,1-difluoroethylene) -poly {1- [4- (Chloromethyl) phenyl] ethylene / 1- [3- (chloromethyl) phenyl] ethylene / 1- (4-sulfophenyl) ethylene} poly (1,1-difluoroethylene) -poly {1- [4- (chloromethyl) phenyl] ethylene / 1- [3- (chloromethyl) phenyl] ethylene / 1- (4-sulfophenyl) ethylene}, poly {1-phenylethylene / 1- [ethane-1,1,2-tolyl-1] -(4,1-phenylene)] sulfonyloxyzincoxysulfonyl-4,1-phenylene} ethylene} poly {1-phenylethylene / 1- [ethane-1,1,2-triyl-1- (4,1-phenylene) )] sulfonyloxyzincoxysulfonyl-4,1-phenylene} ethylene}, poly {1-phenylethylene / 1- [ethane-1,1,2-tolyl-1- (4,1-phenylene)] sulfonyloxyzincoxysulfonyl-4 , 1-phenylene} ethylene} / but-2-ene-1,4-diyl / 1-vinylethylene} poly {1-phenylethylene / 1- [eth ane-1,1,2-triyl-1- (4,1-phenylene)] sulfonyloxyzincoxysulfonyl-4,1-phenylene} ethylene / but-2-ene-1,4-diyl / 1-vinylethylene}, poly [1 -Methyl-1-({2-[(nonadecafluorononyl) oxy] ethoxy} carbonyl) ethylene] -poly [1-phenylethylene / 1- (4-sulfophenyl) ethylene]} poly [1-methyl-1 -({2-[(nonadecafluorononyl) oxy] ethoxy} carbonyl) ethylene] -poly [1-phenylethylene / 1- (4-sulfophenyl) ethylene]}.

The adsorbent of the present invention can be produced by immersing a carrier in an aqueous solution containing both hydroxylamines and a polymer having a functional group that interacts with an amino group, followed by drying.
The concentration in the aqueous solution is not limited to hydroxylamines, but is preferably 20% by weight or less, and more preferably about 2% by weight. The concentration of the polymer having a functional group that interacts with an amino group is preferably 80% by weight or less, and more preferably about 4% by weight.
As a specific example, a PSS aqueous solution having a polystyrenesulfonic acid (PSS) concentration of 0.5 to 5% by weight is prepared. Hydroxylamine phosphate (HAP) is added to the PSS aqueous solution to prepare a 2.0 to 2.8% by weight PSS / HAP mixed aqueous solution. Alumina pellets are added to the PSS / HAP mixed aqueous solution and stirred for 24 hours. After stirring, the mixture was filtered and dried at 90 ° C. for 6 hours to produce an adsorbent.
Alternatively, the support may be dipped in an aqueous solution containing hydroxylamines and dried, and then further dipped in an aqueous solution containing a polymer having a functional group that interacts with an amino group and dried.
Further, the above immersion treatment and the drying treatment may be repeated a plurality of times like immersion, drying, immersion and drying.

When the adsorbent of the present invention is a powder or a granular material, the adsorbent may be supported on a support such as supported on a nonwoven fabric or honeycomb, or may be used as a filter. A filter having such a form is suitable for use as a cabin air filter for cleaning automobile interiors. The support is not limited to non-woven fabrics and honeycombs, and fabrics, glasses, resins, paper, and woods can also be used.
As fabrics, natural fibers or synthetic fibers represented by cotton, acrylic fiber, polyester fiber, wool, cellulose fiber, polyurethane, polyvinyl alcohol fiber, vinylon; as glass, glass beads, glass fiber; as resin, Styrol resin, ABS resin, polycarbonate resin, POM resin (polyacetal resin), acrylic resin, vinyl chloride resin, phenol resin, urethane resin, epoxy resin, polyethylene resin, polypropylene resin, polyvinyl acetate, polyvinylidene chloride, polymethyl methacrylate And synthetic resins represented by urea resin, melamine resin, alkyd resin, ion exchange resin, polyamide resin, and polyimide resin.
In order to support the adsorbent on the support, the adsorbent dispersion may be dipped in the support and dried, or instead of the dipping treatment, a cast method, a roll coat method, a spin coat method, a spray method may be used. It may be applied by a coating method such as.

Hereinafter, the present invention will be described in more detail by taking acetaldehyde as an example of aldehydes.
The inventors of the present invention have first worked on the preparation of an aldehyde removal filter using activated carbon, but since activated carbon is a non-polar adsorbent that physically adsorbs gas in its micropores, various kinds of materials can be used regardless of polarity. Although gas can be adsorbed, desorption is easy, and the adsorbed gas is re-released.

Therefore, the present inventors improved the adsorption amount and stability by chemically reacting with the acetaldehyde on the adsorbent surface in order to produce a high-performance acetaldehyde adsorbent with excellent adsorption amount and stability for practical use. Therefore, we focused on using the following Schiff base reaction.
That is, an adsorption amount and stability are improved by attaching an amino group-containing compound that undergoes a Schiff base reaction with an aldehyde to the adsorbent surface.

Since the present inventors have used 3-aminopropyltrimethoxysilane (APTMS) and hydroxylammonium phosphate (HAP) as such a surface modifier having an amino group (Patent Documents 5 and 6). First, activated alumina modified with these was prepared, and the acetaldehyde adsorption amount was compared.
The adsorbent was prepared by immersing activated alumina in a 4 wt% aqueous solution of APTMS or a 2 wt% aqueous solution of HAP for 24 hours and drying at 90 ° C. for 6 hours.

The adsorption amount of the produced adsorbent was measured with the apparatus shown in FIG. A fan (2) for circulating air in the system and a fan (3) for blowing air into a filter containing an adsorbent were installed in a 9 L capacity desiccator having a gas inlet (1). (4) is an adsorbent, and (5) is a pipe for directly sending air in the system to gas chromatography.
The adsorption test of the produced adsorbent was performed by the following procedures (i) to (viii).
(i) Install 1.0 g of the adsorbent in the system so as not to scatter and rotate the fan (2).
(ii) A certain amount of vaporized acetaldehyde gas is injected into the system from the gas inlet (1).
(iii) Let stand for 4 minutes to make the gas concentration in the system uniform.
(iv) The concentration of acetaldehyde in the system is measured using gas chromatography.
(v) Rotate the fan (3) and leave it for 30 minutes.
(vi) After 30 minutes, stop the fan (3) and measure the acetaldehyde concentration in the system again.
(vii) The adsorption amount is calculated from the concentration before and after the rotation of the fan (3).
(viii) The operation is repeated until the density after rotation of the fan (3) becomes 50% or less of the density before rotation.

The results are shown in FIG. FIG. 2 also shows activated alumina that is not surface-modified for comparison.
The activated alumina alone hardly adsorbed acetaldehyde, but the amount of acetaldehyde adsorbed markedly increased by surface modification with APTMS or HAP. When APTMS and HAP are compared, the adsorption amount of HAP is larger. Since HAP has higher amine polarity than APTMS, it is presumed that acetaldehyde is easily adsorbed.

To find the most suitable compound among hydroxylamines, hydroxylamine hydrochloride ((NH ₃ OH) Cl), hydroxylamine sulfate ((NH ₃ OH) SO ₄ ), hydroxylamine phosphate ((NH ₃ OH) PO ₄ ) The adsorption amount was measured for these three types. Since the number of hydroxylamines per molecule was different, the aqueous solution concentration was adjusted so that the total number of hydroxylamines was the same, so that the hydroxylamine phosphate aqueous solution concentration was 1% by weight. 3 g of alumina pellets were immersed in each aqueous solution with stirring for 24 hours, filtered, and dried at 90 ° C. for 6 hours. The results of the adsorption test are shown in FIG.
FIG. 3 shows that the amount of adsorption is phosphate>sulfate> hydrochloride.

Furthermore, in order to measure the stability of the produced adsorbent, a heat resistance test was performed.
In the heat resistance evaluation, after the adsorbent was placed in an atmosphere of 50 ° C. for 24 hours, the adsorbed amount was measured according to the above procedure, and the comparison was performed before and after heating. The temperature of 50 ° C is assumed to be the temperature in the car in summer. The results are shown in Fig. 4.
From the results of FIG. 4, it was found that when the surface modification with APTMS did not change the adsorption amount before and after heating, the adsorption amount decreased after heating when HAS was used. That is, it was found that although HAS has a larger amount of adsorption, there is a problem in heat resistance stability.
The reason why the heat stability is inferior is considered to be that the hydroxylamine moiety of the hydroxylamine phosphate is liberated and decomposed to reduce the adsorption sites.

Therefore, as a method of improving the heat stability, we studied to suppress the release and decomposition of hydroxylamine by adding a polymer having a functional group that interacts with hydroxylamine.
As shown in the following formula, it is known that an amino group interacts with a sulfone group by van der Waals force.
Vanden-Walls force is physical adsorption and is weaker than chemical adsorption. However, it is considered that release and decomposition can be suppressed more than those without interaction.

As a polymer having a functional group that interacts with hydroxylamine, it was confirmed by X-ray photoelectron spectroscopy (XPS) whether the amino group and the sulfone group interacted with each other using polystyrene sulfonic acid (PSS) of the following formula. . The XPS S (2p) spectrum is shown in FIG.
As shown in FIG. 5, it can be seen that the peak position of PSS is shifted when hydroxylamine phosphate is added (PSS + HAP). From this, it is presumed that the amino group and the sulfone group interact with each other.
Based on the above knowledge, in the present invention, the adsorption amount, heat resistance, and life of the aldehyde adsorbent were improved by allowing the hydroxylamines to coexist with a polymer having a functional group that interacts with the amino group of the hydroxylamines. .
Hereinafter, the present invention will be described more specifically by way of examples.

The effect of adsorbent on the heat resistance associated with the addition of PSS to HAP was evaluated.
The prepared adsorbent was placed in an atmosphere of 50 ° C. for 24 hours, and the accumulated amount of acetaldehyde adsorbed before and after heating was compared. Adsorbent modified with hydroxylamine phosphate (2.0 g) aqueous solution, modified with 0.5 wt.% PSS aqueous solution (HAP 2.2 g), and modified with 5.0 wt.% PSS aqueous solution (HAP 2.8 g) What was done was used. Table 1 shows the amount of adsorption before and after each heating.

From Table 1, it can be seen that the degree of decrease in the amount of adsorption before and after heating is 52%, 31%, and 4% in order, and decreases as the concentration of the PSS aqueous solution increases. This is presumably because the release and decomposition of the hydroxylamine moiety was suppressed by the interaction between the sulfone group of the PSS molecule and the amino group of hydroxylamine phosphate.

Furthermore, the peak change of the amine before and after heating was analyzed using a Fourier transform infrared spectrophotometer (FT-IR). In the analysis, the same sample was used before and after heat treatment. The results are shown in FIG.
A charged amine peak is observed at 3350 cm ^{−1 to} 3150 cm ⁻¹ . When only HAS is attached from the left figure in FIG. 6, it can be seen that the peak that existed before the heat treatment disappears due to the heat treatment. However, when PAP of HAP is added from the right figure in FIG. However, a peak was confirmed at the same position. From this, it can be said that the release / decomposition of hydroxylamine is suppressed by the presence of the PSS molecule.

  From the above results, it was found that heat resistance was improved by adding PSS. This is due to the interaction by van der Waals force between the sulfone group of the PSS molecule and the amino group of hydroxylamine phosphate, and it was found that the heat resistance increases as the PSS concentration increases.

  By attaching hydroxylamines and a polymer having a functional group that interacts with the amino group of hydroxylamines to a carrier, it is possible to provide an aldehyde adsorbent with improved both adsorption amount and stability, and a filter thereof. It was.

1 shows an apparatus for the adsorption test of the present invention. A comparison of the amount of acetaldehyde adsorbed when HAP is attached and when APTMS is attached is shown. The difference of the acetaldehyde adsorption amount by the difference in the kind of hydroxylamine salt is shown. The heat resistance evaluation result of an adsorbent is shown. The XPS chart which shows the interaction of an amino group and a sulfone group. FT-IR chart for heat resistance evaluation.

Explanation of symbols

1: Gas inlet 2: Fan for circulating air in the system 3: Fan for blowing air into the filter 4: Adsorbent 5: Pipe for sending the air in the system to gas chromatography

Claims (6)

One or more of hydroxylamine or an addition salt thereof and a sulfone group are obtained by immersing the carrier in an aqueous solution containing one or more of hydroxylamine or an addition salt thereof and a polymer having a sulfone group and drying. An aldehyde adsorbent characterized by adhering a polymer having a carrier to a carrier. The aldehyde adsorbent according to claim 1 , wherein the addition salt of hydroxylamine is hydroxylamine phosphate, hydroxylamine hydrochloride, hydroxylamine nitrate, hydroxylamine oxalate or hydroxylamine sulfate. The aldehyde adsorbent according to claim 1 or 2 , wherein the polymer chain of the polymer having a sulfone group is polystyrene. The aldehyde adsorbent according to any one of claims 1 to 3 , wherein the polymer having a sulfone group is polystyrene sulfonic acid. The aldehyde adsorbent according to any one of claims 1 to 4 , wherein the carrier is activated carbon or an inorganic oxide. Aldehyde adsorption filter is held to the support aldehydes adsorbent according to any one of claims 1-5.