JPH06319992A - 69-319922 adsorbent - Google Patents

Abstract

PURPOSE:To provide an adsorbent with such advantages as having the same high adsorptive properties as those of active carbon and controlling properties of functional group and no generation of electrically conductive dust, which properties have never been attained by the conventional active carbon. CONSTITUTION:An adsorbent with a specific surface area of at least 1,000m<2>/g and a ratio of micropores with a diameter of 10-30Angstrom of at least 65% wherein an org. arom. polymer is a main component is provided. Such org. arom. polymer as this can be synthesized by making a copolymer of an arom. monovinyl monomer and an arom. polyvinyl monomer into multiporous substance by swelling and gelation and immobilizing stably the multiporous condition by performing high density crosslinking treatment. As electrically conductive dust is not produced, it is possible to use it at a place where an electronic instrument is installed and it is also possible to control freely adsorptive characteristics by controlling the functional group and to use it in a wide range of adsorptive fields.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is as high as activated carbon in adsorbing gas components such as organic solvent gas, monomer vapor, pesticide vapor and poison gas and adsorbing and removing odorous components and color components in liquid phase. The present invention relates to an adsorbent exhibiting adsorption performance. The adsorbent according to the present invention is described in "Activated Carbon-Basics and Applications" edited by Carbon Society of Japan, Kodansha Scientific, Chapter 6 (19).
84), and Seiichi Kondo, "Adsorption Chemistry", Maruzen, Chapter 7 (1991), and can be used for various adsorption applications, as well as controllability of functional groups introduced into adsorbents. And has advantages such as no generation of conductive dust. Therefore, the present invention provides an adsorbent that can be used in a clean room where electronic equipment is installed and can be used for adsorption and removal of a wider range of substances than activated carbon.

[0002]

2. Description of the Related Art Inorganic porous materials represented by activated carbon and activated carbon fibers are used as adsorbents because of their high specific surface area. Activated carbon-based adsorbents having a large amount of micropores with a diameter of 30 Å or less and a high specific surface area have become possible to synthesize, and are used as adsorbents in a gas phase and a liquid phase. The micropores are
Relatively small in gas components or liquid phase (eg molecular weight 50
It is particularly effective for the adsorption of molecules (below 00).

However, it is known that activated carbon and activated carbon fibers have low strength and are powdered by vibration or the like to generate dust. In particular, dust from activated carbon and activated carbon fibers has electrical conductivity, so when attached to electronic devices,
It causes serious problems such as breakdown and malfunction. For this reason, it has been extremely difficult to use an adsorbent such as activated carbon or activated carbon fiber in a clean room where precision equipment is installed. Further, in the manufacturing process of activated carbon or activated carbon fiber, most of the functional groups possessed by the raw materials disappear in the firing process. After firing, it is also difficult to add a functional group by a chemical reaction or the like. These indicate that it is difficult to control the affinity between the adsorbent and the adsorbent, that is, the adsorption property.

On the other hand, in organic resin type adsorbents, JP-A-61-69816 and JP-A-55-18297.
As represented by macroreticular (macro
A granular adsorbent made of a porous copolymer having a reticular structure is known. These organic resin-based adsorbents have advantages that they have a relatively high strength as compared with activated carbon and activated carbon fibers, and that they do not generate the above-mentioned conductive dust. These porous copolymers also have an advantage that the surface condition can be controlled from hydrophilicity to hydrophobicity relatively easily by providing a surface functional group.

However, these organic resin-based adsorbents have a large average pore diameter of 40 Å or more, and a high molecular weight substance typified by a protein in a liquid phase system such as a chromatographic resin. It is most suitable for adsorption separation, but when used as an adsorbent for low molecular weight substances in gas components and liquid phase, the pore size is too large and the amount of adsorption that can be effectively adsorbed is very small. It was

With respect to the above, in the conventional organic resin type adsorbent, for example, in the above-mentioned JP-A-55-18297, "pores having a diameter of 30 Å or less disappear from the polymer structure when the polymer is dried. Virtually no pores at all. " As described above, it has been conventionally considered difficult to produce an adsorbent having a large amount of stable micropores of 30 Å or less as a main component in the organic resin material.

[0007]

Conventionally, inorganic adsorbents represented by activated carbon have many problems in terms of strength and controllability of adsorption characteristics. Is required. However, in the conventional organic resin-based adsorbent, the micropores disappear due to the thermal motion of the molecules, and stable adsorption properties cannot be exhibited.

[0008]

According to the present invention, the total specific surface area determined by the BET method is 1000 m ² / g or more, and the cumulative specific surface area of pore diameters 10 to 30 Å is 65% or more of the total specific surface area. It is an adsorbent mainly composed of an organic aromatic polymer.

Further, in the present invention, in the organic aromatic polymer, the ratio of the aromatic polyvinyl monomer in the raw material monomer is in the range of 0.1 to 8% by weight, and the swelling ratio of the adsorbent is It is possible to provide an adsorbent characterized by being 100% or less.

Further, according to the present invention, in an adsorbent made of a copolymer having a chloromethylstyrene component ratio of 85% by weight or more, the chlorine content of the adsorbent is 4% by weight or less. Material can be provided.

The organic aromatic polymer in the present invention is synthesized by polymerizing an aromatic monovinyl monomer and an aromatic polyvinyl monomer. As the aromatic monovinyl monomer,
Various substitution products of styrene represented by styrene, chloromethylstyrene, methylstyrene (o, m, p) and α-methylstyrene are used. Divinylbenzene (for example, commercially available divinylbenzene having an ethylvinylbenzene content of less than 45% by weight) is most suitable as the aromatic polyvinyl monomer, and other divinylbenzene derivatives such as trivinylbenzene are also suitable. Corresponding ones can also be used. Further, both of the aromatic monovinyl monomer and the aromatic polyvinyl monomer in which the benzene ring portion is replaced with a naphthalene ring can be similarly used.

The copolymerization of vinyl monomer in the present invention is
Suspension polymerization is most desirable. The suspension polymerization is preferably carried out in a water / organic solvent system. The organic solvent dissolves the vinyl monomer but does not dissolve the copolymer after polymerization, and has a boiling point of 70.
A wide range of solvents can be used as long as they are in the range of 180 ° C. When the boiling point is 70 ° C. or lower, the temperature that can be heated in the polymerization is limited by the boiling point of the solvent, which may cause a problem that heating cannot be sufficiently performed in the polymerization. When the boiling point is 180 ° C. or higher, high energy is required to remove the solvent, which is not desirable.

The total specific surface area of the adsorbent in the present invention determined by the BET method is preferably 1000 m ² / g or more,
When it is lower than 1000 m ² / g, the adsorption amount per unit weight becomes low, which is not desirable. At the same time, the cumulative specific surface area of the pore diameters of 10 to 30Å is preferably 65% or more, more preferably 70% or more of the total specific surface area. When the cumulative specific surface area of the pore diameters of 10 to 30Å is lower than 65%, in the adsorption application intended by the present invention,
There are many pores that do not substantially affect adsorption, leading to a decrease in adsorption capacity, and the diffusion and transfer of the substance to be adsorbed to the micropores with a pore diameter of 10 to 30 Å are hindered by the pores with a diameter of more than 30 Å It is not desirable because it causes a decrease in the adsorption rate.

The formation of micropores is started by immersing and swelling the above-mentioned copolymer in a solvent to form a gel. For immersion and swelling, it is desirable to use a solvent having a volume twice or more that of the copolymer, and the immersion time is desirably 2 hours or more. The types of solvents include dichloroethane (ethylene dichloride), chlorobenzene, dichlorobenzene,
Chlorine-based solvents such as trichlorethylene and perchlorethylene are most desirable, and at the same time, the boiling point range of the solvent is desirably 80 ° C. or higher. When the boiling point of the solvent is lower than 80 ° C., there is a possibility that the heat necessary for the reaction may not be sufficiently given in the stabilization treatment of the micropores by the crosslinking treatment described later. Among the solvents other than those mentioned above, there are solvents having the same gelling effect when heated or stirred, but these solvents can be similarly preferably used as long as they have a boiling point of 80 ° C or higher. The micropores generated by the swelling and gelation as described above are thermally unstable and disappear due to molecular motion when the solvent is removed as it is.

The most important point in the present invention is the treatment for stabilizing the micropores existing in the gel state by the high density crosslinking under the above-mentioned solvent immersion. Crosslinking can be carried out by adding a crosslinkable functional group to the monovinyl monomer or polyvinyl monomer and reacting them. In the pore immobilization treatment, it is important that the density of the actually reacted cross-linking group is high, and even if a large amount of the cross-linkable functional group remains unreacted, it is an object of the present invention. Can not be achieved.

Regarding this cross-linking, a copolymer is prepared in advance by the above-mentioned polymerization using a monovinyl monomer or a polyvinyl monomer having a cross-linking reactive functional group, and the obtained copolymer is immersed in a solvent. After being swollen and made into a gel state, the functional group can be subjected to a crosslinking reaction. On the other hand, after polymerizing the vinyl monomer, a cross-linking reactive functional group may be introduced. In this case, after the copolymer is prepared by the polymerization of vinyl monomer, a crosslinkable functional group is introduced into the obtained copolymer, and the copolymer is swollen and gelated by immersion in a solvent. It is possible to crosslink the introduced functional group.

A more specific method for immobilizing pores is to use chloromethylstyrene as a monovinyl monomer, and use a chloromethyl group in the presence of a Friedel-Crafts catalyst (zinc chloride, tin chloride, aluminum chloride, etc.). (-CH ₂
Cl group) can be reacted to cause a crosslinking reaction.
The fact that the chloromethyl group has a cross-linking reactivity is shown in Polymer Experimental Science Course, Volume 12-4, Kyoritsu Shuppan, 1980. In this case, in order to increase the reaction efficiency of the crosslinking reaction,
In addition to the basic operation of introducing dry nitrogen during the reaction, it is necessary to avoid mixing of water into the reaction system by various methods described below. The heating temperature is preferably 80 ° C or higher. If the heating temperature is lower than 80 ° C., the reaction rate will decrease, and it will be difficult to achieve the object of the present invention. Further, the reaction time requires heating for at least 8 hours in order to increase the reaction efficiency, and is preferably 15 hours or more. Since chlorine is desorbed from the copolymer after the reaction, the reaction efficiency can be measured by quantifying the amount of chlorine remaining in the adsorbent after the pore fixing treatment.

It is also possible to introduce a chloromethyl group after polymerizing the above-mentioned various monomers and to carry out the same crosslinking reaction as above. For example, styrene can be chloromethylated and used, or paramethylstyrene can be chlorinated and chloromethylated and used in the same manner.

A specific method for increasing the ratio of the cumulative specific surface area having pore diameters of 10 to 30Å to the total specific surface area will be described. The content of the aromatic polyvinyl monomer in all the vinyl monomers added as a raw material is preferably in the range of 0.1 to 8% by weight. In the finally obtained adsorbent, the ratio (S10-30 / S) of the cumulative specific surface area (S10-30) of the pore diameter 10 to 30Å to the total specific surface area (S) and the aromatic polyvinyl monomer This is because the content has the relationship shown in FIG. From Figure 1,
In order for the ratio (S10-30 / S) to be 65% or more, the content ratio of the aromatic polyvinyl monomer is preferably 8% by weight or less, and further to be 70% or more, the content ratio of the aromatic polyvinyl monomer. Is preferably 5% by weight or less. In addition, the content ratio of the aromatic polyvinyl monomer is 0.1
When the content is less than the weight%, there is a problem that the copolymer is dissolved in the solvent used in the gelation treatment described later, which is not desirable.

Next, a specific method for obtaining a high specific surface area will be described. In the adsorbent of the present invention, the higher the degree of immobilization of pores (degree of crosslinking), the more stable the micropores are, without being affected by molecular thermal motion. As a result, the surface area is increased by increasing the amount of effectively acting pores. In the present invention, the crosslinking reaction is 70 mol% or more based on the total number of moles of the vinyl monomer molecules used (degree of crosslinking is 70% or more).
Is important to achieve. The degree of cross-linking is obtained as the molar amount of the functional group that actually undergoes the cross-linking reaction in the pore fixing treatment, and the degree of cross-linking is easily obtained by measuring the swelling ratio of the adsorbent. The fact that the degree of cross-linking can be expressed as a function of the swelling rate is described in "Plastic Materials Course 10-Polyester Resin", Nikkan Kogyo Shimbun, 1970, Chapter 3, p.
J. It is described by citing the results of the study of Flory et al.
The relationship between the degree of crosslinking and the swelling ratio in the present invention is shown in FIG.
From FIG. 2, the degree of crosslinking is 70% or more, that is, the swelling rate is 100%.
In the case of having a high degree of crosslinking corresponding to the following range, it corresponds to the glass transition temperature of pure styrene polymer.
Even when heated at 00 ° C. (nitrogen atmosphere) for 12 hours, stable micropores whose pore distribution does not substantially change can be obtained.

The relationship shown in FIG. 2 was obtained by the following measuring method. In the adsorbent sample before and after the pore immobilization treatment, the amount of crosslinkable functional groups (for example, the number of moles of —CH ₂ Cl groups) was measured, and the actual amount of reacted functional groups (moles) was determined from the difference between the two. , And the degree of cross-linking (%) converted to the value (percentage) per total number of moles of vinyl monomer molecules of the adsorbent material
And The swelling ratio was obtained by first crushing an adsorbent (dry weight: 0.5 g) and sieving to a size of 25 ± 5 μm, and measuring the apparent volume (V0). Chloroform (15g), which has a small molecular size and a high swelling effect
Was added and left for 24 hours, and then the volume (V1) of the adsorbent after swelling was measured while being immersed in chloroform. The swelling ratio (%) was calculated by the following formula.

[0022]

Swelling rate (%) = ((V1−V0) / V0) × 100 Further, the proportion of polyvinyl monomer in the raw material is 0.1 to 8%.
The relationship in FIG. 2 was almost the same and did not change even when the range was changed.

In the copolymer obtained by further performing polymerization or a treatment after the polymerization, it is desirable that the proportion of chloromethylstyrene is 85% by weight or more in order to increase the degree of crosslinking. When the proportion of chloromethylstyrene is lower than 85% by weight, a sufficient degree of cross-linking cannot be obtained because the amount of cross-linking reactive functional groups is insufficient. The chlorine content remaining in the adsorbent is preferably 4% by weight or less. When the residual chlorine amount is higher than 4% by weight, it means that a large amount of unreacted crosslinking-reactive functional groups remain, which is not desirable.

In order to increase the reaction rate of the crosslinking reaction, it is most important to avoid mixing of water, and the following method is effective. After carrying out suspension polymerization, the polymerized sample is immersed in a large amount of methanol and heated under reflux to completely replace methanol with water. If vacuum drying is carried out after this operation, water will not remain inside the pores, and the reaction efficiency can be increased in the subsequent crosslinking reaction. When a small amount of a polymerization initiator is added during the above heating under reflux, the remaining monomers can be polymerized, and the polymerized product can be stabilized and the pores can be made uniform at the same time. It is also effective to add a dehydrating agent to the reaction system for the above crosslinking reaction. As the dehydrating agent, any one can be used as long as it does not decompose or cause a side reaction when added to the above reaction system. An inorganic salt such as sodium sulfate or an adsorbent such as activated carbon can also be used as a dehydrating agent. Furthermore, it is very effective to use a porous non-woven fabric made of polypropylene or fluororesin or a container having fine holes in which the dehydrating agent is wrapped, because the separation is easy after the reaction. The solvent used as the swelling gelling agent is preferably used after being dehydrated with a molecular sieve and then filtered with a filter paper.

The method for determining the specific surface area in the present invention is shown below. The adsorption amount of nitrogen gas was measured at the liquid nitrogen temperature, and the total specific surface area was calculated by the BET method.
The pore distribution was determined by the Ston-Inkley method, and the cumulative specific surface area of the pore diameters of 20Å to 30Å was calculated. Specifically, the measurement was performed using Carlo Erba Co., soapmatic, SSII-80.

A commercially available aromatic polyvinyl monomer such as divinylbenzene contains a large amount of aromatic monovinyl monomer such as ethylvinylbenzene. Therefore, the amounts of the aromatic monovinyl monomer and the aromatic polyvinyl monomer in the present invention are all displayed as the amount of each pure monomer in terms of purity, not the amount of the raw material containing impurities. I shall.

[0027]

EXAMPLES The present invention will be described below with reference to examples.

Example 1 10 equipped with a stirrer, reflux condenser, thermometer, nitrogen inlet tube
In a 00 cc four-necked flask, 1 g of polyvinyl alcohol (polymerization degree: 500) was previously dissolved in 750 cc of deionized water, a stirrer was set to 300 rpm, and 98 g of chloromethylstyrene and divinyl were introduced with nitrogen introduced. 1.1 g of benzene and 0. ethyl vinylbenzene.
9 g, benzoyl peroxide (25% water content) 7 g, and toluene 150 g are added. The oil bath was heated and the mixture was kept at 80 ° C. for 8 hours. After allowing to cool, washing with water and filtration are sufficiently performed. Put the polymer in the same reaction vessel as above, 900 cc of methanol, benzoyl peroxide (25% water content)
After adding 2 g, stirrer at a speed of 150 rpm for 5
Reflux for a period of time. The obtained sample is 300 cc
After washing and filtering with methanol of 1 hour, at 60 ℃ for 10 hours, 1
Vacuum drying was performed at 00 ° C. for 10 hours (polyvinyl monomer ratio = 1.1%). Further, subsequently, 30 g of the dried sample and 400 cc of dichloroethane dehydrated by the molecular sieve 4A for 40 hours or more were put into a 1000 cc four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube. Further, 20 g of anhydrous sodium sulfate was completely wrapped with a polypropylene non-woven fabric and put into dichloroethane. Here, a sealed state in which moisture did not enter from the outside was made, and it was left at room temperature for 20 hours for swelling gelation. Subsequently, in a state where nitrogen was introduced, 50 g of stannic chloride was added, and the mixture was stirred and heated in the nitrogen atmosphere as it was.
Refluxed for 0 hours. After allowing to cool, 300 cc of acetone was slowly added dropwise over about 15 minutes while cooling in a water bath.
After the sample was filtered to remove the dehydrating agent wrapped with the non-woven fabric, the sample was sequentially put into three kinds of cleaning solutions of 1000 cc of 10% hydrochloric acid aqueous solution, deionized water, and acetone, followed by stirring and filtering. 100 samples in vacuum dryer
Dried at 24 ° C. for 24 hours. Characteristics of sample: total specific surface area (S) 1350 m ² / g, cumulative specific surface area of pore diameter 10 to 30 Å (S10-30) 1020 m ² / g (S10-
30 / S × 100 = 75.6%), swelling ratio 74%, moisture content 0.9% at relative humidity 70%, residual chlorine content 3.2.
% By weight.

Example 2 90 g of chloromethylstyrene, 5.5 of divinylbenzene
g and ethyl vinylbenzene 4.5 g, toluene 30
cc, using 7 g of benzoyl peroxide (25% water content),
The mixture was kept at 80 ° C. for 6 hours for polymerization, and then the same treatment as in Example 1 was performed (polyvinyl monomer ratio =
5.5%). Further, after swelling gelation with 400 cc of dichloroethane, 70 g of zinc chloride was added as a catalyst and the mixture was refluxed for 48 hours. The other conditions were the same as in Example 1. Sample characteristics: Total specific surface area (S) 1050 m ² /
g, cumulative specific surface area of pore diameter 10 to 30 Å (S10-3
0) 760 m ² / g (S10-30 / S × 100 = 7)
2.3%), the swelling rate was 76%, the moisture content was 0.6% at a relative humidity of 70%, and the residual chlorine amount was 2.8% by weight.

Example 3 85 g of styrene, 8.3 g of divinylbenzene and 6.7 g of ethylvinylbenzene, benzoyl peroxide (25%
Polymerization was performed under the same conditions as in Example 1 using 7 g of water-containing material and 150 g of toluene (polyvinyl monomer ratio =).
8.3%). Further, 15 g of the dried sample of the above polymer and 50 g of chloromethyl methyl ether were placed in a 300 cc four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, and left for 30 minutes. At this time, the polymerized sample was in a swollen state with chloromethyl methyl ether. With the nitrogen introduced, 50 cc of dried dichloroethane was added, and the reaction system was cooled to about 0 to 3 ° C with ice water. In the cooled state, 25 g of stannic chloride was slowly added dropwise over about 20 minutes, and 2
It was left standing for a while to proceed the chloromethylation reaction. Next, after adding 150 cc of dichloroethane in a nitrogen atmosphere, the reaction system was returned to room temperature and left standing for 3 hours to cause swelling gelation, and then the reaction system was heated and refluxed for 20 hours. After this,
The same cleaning treatment as in Example 1 was performed. Characteristics of sample: total specific surface area (S) 1030 m ² / g, pore diameter 10
~ 30Å cumulative specific surface area (S10-30) 700 m ² /
g (S10-30 / S × 100 = 68.0%), swelling ratio 76%, relative humidity 70%, moisture content 1.2%, residual chlorine content 2.3% by weight.

Example 4 10 g of the sample obtained in Example 1 was added to dichloroethane 5
Place in 0 cc and leave for 2 hours. While cooling the reaction system with water, 50 g of chlorosulfonic acid was gradually added dropwise, and the mixture was stirred at room temperature for 4 hours. Next, glacial acetic acid 5 with ice cooling to 0-2 ° C
0 g was gradually added dropwise and stirred for 1 hour. 5 reactants
The mixture was placed in a container of 000 cc, separated by gradient separation, filtered, washed with a large amount of acetone, and vacuum dried at 100 ° C. for 24 hours. From the results of elemental analysis, 0.4 sulfonic acid groups were introduced per benzene aromatic ring. Sample characteristics: Total specific surface area (S) 1360 m ² /
g, cumulative specific surface area of pore diameter 10 to 30 Å (S10-3
0) 1090 m ² / g (S10-30 / S × 100 = 8)
0.1%), the swelling rate was 71%, the relative humidity was 70%, the moisture content was 59.4%, and the residual chlorine content was 3.0% by weight.

Comparative Example 1 As a comparative example, SP-8, which is a typical example of a conventional commercially available organic resin-based adsorbent (styrene-divinylbenzene copolymer).
50 (Mitsubishi Kasei), Amberlite XAD-4
The characteristics of activated carbon fiber AN-065 (Toyobo Co., Ltd.) as a representative example of the carbon-based adsorbent are shown in Table 1 together with the results of the examples.

The moisture content of the adsorbent in the present invention is determined by JIS
The measurement was performed according to the hygroscopicity test of Z0701-1977.

[0034]

[Table 1]

[0035]

As described above, the adsorbent according to the present invention has a large number of stable micropores having a pore diameter of 30 Å or less, and exhibits the same excellent gas component adsorbability as activated carbon. In addition, no conductive dust is generated, the control of functional groups is very easy, and it has many characteristics that conventional adsorbents do not have. Therefore, the present invention can be usefully used in a wide range of adsorption applications and can bring great industrial utility.

[Brief description of drawings]

FIG. 1 shows the content of aromatic polyvinyl monomer and 10 to 3
It is a figure which shows the relationship with the ratio of the micropore of 0Å.

FIG. 2 is a diagram showing a relationship between a swelling ratio and a degree of crosslinking.

Claims (3)

[Claims] 1. The total specific surface area determined by the BET method is 10
An adsorbent mainly composed of an organic aromatic polymer, which has a cumulative specific surface area of 00 m ² / g or more and a pore diameter of 10 to 30 Å of 65% or more of the total specific surface area. 2. The organic aromatic polymer is obtained by copolymerizing an aromatic monovinyl monomer and an aromatic polyvinyl monomer, and the aromatic polyvinyl monomer in the raw material monomer. Is in the range of 0.1 to 8% by weight,
The adsorbent according to claim 1, wherein the swelling rate is 100% or less. 3. A ratio of a chloromethylstyrene component in the organic aromatic polymer is 85% by weight or more, and a chlorine content is 4% by weight or less.
The adsorbent according to claim 2.