JPH06319991A - Adsorptive separation - Google Patents

Abstract

PURPOSE:To perform inexpensively and efficiently adsorptive separation of an aimed isomer from a mixture of isomers. CONSTITUTION:A clay intercalation compd. is used as an adsorbent and after an aimed substance is adsorbed thereon by bringing it into contact with a mixture of isomers, the aimed substance is separated by eliminating it therefrom. In another way, unnecessary substances are adsorbed to obtain the aimed substance from the mixture. It is possible thereby to perform easily and efficiently separation of isomers each other which can be hardly done by means of the conventional techniques as the clay intercalation compd. gives a large fine pore diameter and the fine pore diameter can continuously be controlled. It is also possible to easily control selectivity of adsorption and to cope with various purposes for separation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adsorption separation method, and more particularly, to a highly efficient adsorption separation method for isomers using a clay intercalation compound.

[0002]

2. Description of the Related Art Separation process is a basic process in chemical engineering, such as distillation method, crystallization method, supercritical extraction method, separation method by complex formation (inclusion compound, addition compound, complex formation, etc.), etc. It has been known. However, when attempting to separate isomers by distillation, which is the most common separation method, isomers usually require a multi-step process and a large amount of energy because their boiling points are close to each other. To do.
In particular, a compound having a large molecular diameter (for example, an aromatic compound having two or more rings) has a high boiling point, so that separation of isomers by a distillation method is extremely difficult. Further, the crystallization method, the supercritical extraction method, and the separation method by forming a complex have problems such as high separation cost or poor separation efficiency.

In recent years, a method using zeolite has been widely used as a method for separating isomers. That is, isomers having different molecular diameters are separated by utilizing the pore size of zeolite.

[0004]

However, this method cannot separate isomers having a pore size larger than that of zeolite,
Further, since it is difficult to continuously control the pore size of zeolite, there is a drawback that the separation efficiency is poor.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a method for inexpensively and efficiently adsorbing and separating a desired isomer from an isomer mixture.

[0006]

According to the adsorption separation method of claim 1, a mixture of a substance to be separated and an isomer of the target substance or other impurities (hereinafter referred to as "isomer mixture") is selected. A method for separating the target substance, wherein the mixture is brought into contact with an adsorbent to adsorb the target substance on the adsorbent, and then the target substance is desorbed from the adsorbent, A clay intercalation compound is used as the agent.

The adsorption separation method according to claim 2 is a method of separating the target substance from a mixture of the target substance and an isomer of the target substance or other impurities, wherein the mixture is an adsorbent. In the method in which the isomer or other impurities are adsorbed to the adsorbent by contacting with the adsorbent to form only the target substance from the mixture, a clay intercalation compound is used as the adsorbent.

A third aspect of the adsorption separation method according to the first aspect is that the adsorption treatment and the desorption treatment are performed in a liquid phase or a gas phase.

The adsorption separation method according to claim 4 is the method according to claim 1 or 2 or 3, wherein the clay intercalation compound is a pore of a clay-crosslinked porous body in which an inorganic pillar is inserted between layers of a swelling clay mineral. It is characterized in that a hydrolysis product of a metal salt is deposited on the part.

The adsorption separation method of claim 5 is the method of claim 4, wherein the clay intercalation compound is a metal salt in the pores of a clay-crosslinked porous body in which pillars of an inorganic substance are inserted between layers of swelling clay minerals. The porous body formed by depositing the hydrolysis product of 1. is heated to 100 to 800 ° C.

The adsorption separation method according to claim 6 is the method according to claim 1 or 2 or 3, wherein the clay intercalation compound is a pillar of a clay-crosslinked porous body in which an inorganic pillar is inserted between layers of a swelling clay mineral. It is characterized in that a composite with a pillar is formed.

The adsorption separation method of claim 7 is the method of claim 6, wherein the clay intercalation compound comprises a pillar of a clay crosslinked porous body in which pillars of an inorganic material are inserted between layers of a swelling clay mineral, and the clay intercalation compound is combined with the pillar. 10 porous materials formed by
It is characterized by being heated to 0 to 800 ° C.

The adsorption and separation method according to claim 8 is characterized in that, in the method according to any one of claims 1 to 7, the isomer is a polycyclic aromatic compound.

An adsorption separation method according to a ninth aspect is the method according to any one of the first to seventh aspects, wherein the isomer is an aliphatic compound.

It is known that a clay-crosslinked porous body having inorganic pillars inserted between layers of a swelling clay mineral has a pore size larger than that of zeolite. The present inventor has developed a method for controlling the pore diameter while investigating the method for synthesizing the clay-crosslinked porous body and controlling the pore diameter of the clay-crosslinked body (Japanese Patent Application Laid-Open No. 4-2191931; Gazette). As a result of intensive studies on the use of the crosslinked clay, the mixture of isomers was brought into contact with the clay intercalation compound in the liquid phase or in the gas phase, and the desired isomer was adsorbed on the adsorbent, and then the adsorbent Desorb the adsorbate. Alternatively, it has been found that the unnecessary isomers are adsorbed on the adsorbate and only the target substance is obtained from the mixture, whereby the isomers can be efficiently separated at low cost. In particular, this clay intercalation compound has a larger pore size than zeolite and can control the pore size continuously, so large isomer molecules that were difficult to separate with zeolite, such as polycyclic aromatic isomers and aliphatic isomers It was found to be effective for the separation of isomers of. The present invention has been completed based on the above findings.

The present invention will be described in detail below. First, the clay intercalation compound used as an adsorbent in the present invention will be described.

A method for synthesizing a clay-crosslinked porous body in which an inorganic pillar is inserted between layers of a swelling clay mineral is already known. The swelling clay mineral is a cation (cation) -exchangeable silicate clay mineral having a layered structure, and examples thereof include smectite group clay minerals such as montmorillonite, beidellite, hectorite, saponite, and nontronite. In addition, swellable fluoromica-based minerals that are artificial compounds and substitution products of the same type are also included in this. Cations such as sodium ions and calcium ions are coordinated between the layers of these swelling clay minerals, and these ions have the property of easily exchanging with other cations (ion exchange property). . By substituting the exchangeable cations between the layers with another large bulky cation, a porous body in which the layers are spread can be obtained. That is, the bulky cations play a role of supporting pillars for supporting the silicate layer of the swelling clay, and expand the layers, and those having such a role are generally called pillars. Moreover, when a porous body having such pillars inserted therein is fired, the pillars become pillars of an oxide. Such a compound is called an intercalation compound or a clay-crosslinked porous body. Conventionally, as such a compound, a clay-crosslinked porous body has been obtained by ion-exchange introducing polynuclear cations such as aluminum, zirconium, titanium, and iron between layers (for example, JP-B-62-2013).
No. 0, JP-A-54-5884, JP-B-63-
28842, JP-A-59-216631. However, since the size of the pores in these clay-crosslinked porous bodies is limited to one type, it is not suitable for separating isomers using pores such as zeolite.

However, the pore size of these clay-crosslinked porous bodies can be easily controlled by depositing a hydrolysis product of an aqueous solution of a metal salt such as a metal hydroxide or a basic salt of a metal in the pores. . For example, after adding and mixing the clay cross-linked porous body to the metal salt aqueous solution to prepare a suspension, hydrolyzing the metal salt aqueous solution to deposit a hydrolysis product in the pores of the clay cross-linked porous body. The pores are controlled by (Japanese Patent Application Laid-Open No. 4-2191931).

Another method for controlling the pore size is a method of forming a composite with pillars of a clay-crosslinked porous body. For example, the pores can be controlled by contacting the clay-crosslinked porous material with a reactant that selectively reacts with the pillar constituents in the liquid phase or the gas phase to form a composite with the pillars (Japanese Patent Laid-Open No. H10 (1999) -242242). 4-2950
08 publication).

Since the clay-crosslinked porous body whose pore size is controlled in this way has a pore size larger than that of zeolite and the pore size can be controlled continuously, efficient separation of isomers can be achieved. In addition, it is effective for separating large isomer molecules, which were difficult to separate with zeolite.

There are roughly three functions of separation using the pores of such a clay-crosslinked porous body. One is the effect of sieving using the size of the pores. That is, molecules larger than the pore size are not adsorbed in the pores, and as a result, isomer molecules having different molecule sizes can be separated (equilibrium molecular sieving effect).

The second is the kinetic molecular sieve effect. That is, the separation is based on the difference in the diffusion rate of molecules in the pores.

The third is separation based on the affinity of the pores. Examples of the effect of affinity include the effect of selective adsorption due to hydrophilic-hydrophobic recognition of pores and the selective adsorption of polar molecules due to the presence of an electrostatic field of pores.

Specific isomer separation according to the present invention is performed as follows. First, the isomer mixture is brought into contact with the clay intercalation compound to adsorb the target substance (one isomer) to the clay intercalation compound. Then, the adsorbed target substance is desorbed from the clay intercalation compound. The adsorption of the target substance to the clay intercalation compound and the desorption of the clay intercalation compound from the clay intercalation compound can be carried out in the liquid phase or in the gas phase, and the adsorption temperature is preferably about room temperature to 300 ° C. Conversely, unnecessary substances may also be adsorbed to the clay intercalation compound by bringing the isomer mixture into contact with the clay intercalation compound. When the equilibrium molecular sieving effect is used, the adsorption operation is preferably carried out under the condition that sufficient adsorption equilibrium can be obtained by batch treatment. When utilizing the kinetic molecular sieving effect, the separation operation is performed by means such as column chromatography. When the effect of separation due to the affinity of the pores is used, it can be obtained by heating the clay-crosslinked porous body to 100 to 800 ° C. That is, a porous body obtained by depositing a hydrolysis product of an aqueous solution of a metal salt such as a metal hydroxide or a basic salt of a metal in the pores of the clay-crosslinked porous body, or a pillar of the clay-crosslinked porous body and a pillar. The porous body formed by the composite is 100-800.
By heating to ° C, its affinity changes significantly. For example, if there are metal hydroxides in the pores, 30
Since the hydroxide is dehydrated by heating at 0 to 500 ° C, the affinity can be greatly controlled. Therefore, the adsorption separation efficiency can be exhibited by changing the heat treatment temperature according to the isomer to be separated.

In the present invention, the kinds of isomers to be adsorbed and separated are not particularly limited, but the present invention adsorbs large isomer molecules which are difficult to separate with conventional zeolites, such as polycyclic aromatic compounds and aliphatic compounds. Especially effective for separation.

[0026]

[Function] Since the clay intercalation compound can obtain a large pore size and can control the pore size continuously, it is easy and efficient to separate isomers which are difficult to separate by the conventional method. Can be done

The adsorption separation using such a clay intercalation compound can be industrially advantageously carried out in a liquid phase or a gas phase.

The pore diameter of the clay intercalation compound is controlled by a porous body obtained by depositing a hydrolysis product of an aqueous solution of a metal salt such as a metal hydroxide or a basic salt of a metal on the pore portion of the clay crosslinked porous body. This can be easily carried out by forming a clay-crosslinked porous body pillar into which a composite with pillars is formed.

Further, 100% of such a clay-crosslinked porous body is prepared.
By heating to ~ 800 ° C, the affinity of the clay intercalation compound can be changed and the adsorption separation efficiency can be increased.

[0030]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 0.2 M (= mol / l) aqueous solution of aluminum chloride 75
While stirring 0 ml, 3750 ml of 0.1 M sodium hydroxide aqueous solution was added thereto at a rate of 50 ml / hr. This was heated and refluxed at 98 ° C. for 48 hours to synthesize an aluminum polynuclear cation. To this was added 15 g of sodium tetrasilicon mica (made by Topy Industries) at room temperature,
The mixture was further heated and refluxed at 98 ° C. for 24 hours. Next, tetrasilicon mica was separated by centrifugation and further washed with distilled water until chlorine ions were not observed in the washing liquid. Thereafter, the centrifuged tetrasilicon mica was heated at 500 ° C. for 4 hours to obtain a clay-crosslinked porous body in which pillars of Al ₂ O ₃ were coordinated between the layers of the tetrasilicon mica. This clay-crosslinked porous body 2.
0 g was added to 200 ml of 0.1 M nickel nitrate aqueous solution,
1 ml of 0.1 M sodium hydroxide aqueous solution with stirring
/ Hr as shown in Table 1, OH / Ni (0.1-0.
4) was changed and added (it is not added in sample No. 1).
As a result, a clay-crosslinked porous body having various amounts of nickel hydroxide deposited in the pores was obtained. This clay-crosslinked porous body was further heated at 400 ° C. for 3 hours to convert nickel hydroxide to nickel oxide, and to prepare sample No. 1 to 5 clay intercalation compound samples were obtained.

Separately, 2,3-dimethylnaphthalene 200
mg and 1,6-dimethylnaphthalene 200 mg were added to hexane 1 liter to prepare an isomer mixed solution. Add 1.0 g of each sample to 100 ml of this solution,
Adsorption was carried out by stirring at 5 ° C for 5 days. Next, the adsorbent and the solution were separated by filtration, the adsorbate in the adsorbent was desorbed with a para-xylene solution, and the components of the adsorbate were quantified by gas chromatography. The results are shown in Table 1. Here, the adsorption selectivity is (amount of adsorbed 2,3-dimethylnaphthalene)
/ (Amount of 1,6-dimethylnaphthalene adsorbed).

From Table 1, the synthesized clay intercalation compounds are:
It was confirmed that the pores were controlled by the OH / Ni ratio, which changed the adsorption selectivity, and was excellent as an adsorbent for separating dimethylnaphthalene isomers.

[0034]

[Table 1]

Example 2 1 liter of a 0.5 M zirconium oxychloride aqueous solution was added to 1 liter.
The mixture was heated under reflux at 00 ° C for 1 hr. To this, at room temperature, Na-montmorillonite (“Kunipia-F” manufactured by Kunimine Industries) 30
g was added, and the mixture was further heated under reflux at 100 ° C. for 1 hr. The montmorillonite was separated by centrifugation and further washed with distilled water until chlorine ions were not observed in the washing liquid. After this, centrifuge the montmorillonite to 100
After drying at ℃, a clay-crosslinked porous material in which zirconium polynuclear cations were coordinated between the layers of montmorillonite was obtained. 2.0 g of this clay-crosslinked porous material was added to 200 ml of 0.1 M magnesium nitrate aqueous solution, and 0.1 M sodium hydroxide aqueous solution was stirred at 1 ml / hr with stirring to obtain OH as shown in Tables 2 and 3.
/ Hg (0.1-0.4) was changed and added (No. 6,
No addition was made for 11. ). As a result, a clay-crosslinked porous body having various amounts of magnesium hydroxide deposited in the pores was obtained. Part of this clay-crosslinked porous body (No. 11 to 15)
Sample No. 3 was baked at 500 ° C. for 4 hours to obtain zirconium polynuclear cation zirconium oxide between layers. 6 ~
Fifteen clay intercalation compound samples were obtained.

Separately, perfluorocaprylic acid (C ₇ F ₁₅
COOH) normal and iso form 400mg each 1
An isomer mixed solution was prepared by adding liter of n-decane. 1.0 g of each sample was added to 100 ml of this solution, and the mixture was stirred at 25 ° C. for 5 days for adsorption. Next, the adsorbent and the solution were separated by centrifugation, the adsorbate in the adsorbent was desorbed with a para-xylene solution, and the components of the adsorbate were quantified by gas chromatography. The results are shown in Tables 2 and 3. Here, the adsorption selectivity is (amount of adsorbed n-perfluorocaprylic acid) / (amount of adsorbed iso-perfluorocaprylic acid).

From Tables 2 and 3, the synthesized clay intercalation compound has its pores controlled by the OH / Mg ratio.
Further, it was confirmed that the adsorption selectivity was changed according to the heat treatment, and that it was excellent as an adsorbent for separating isomers of perfluorocaprylic acid.

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

As described in detail above, according to the adsorption separation method of the present invention, the target substance is selectively and easily adsorbed and separated from the isomer mixture, which has hitherto been difficult to separate. It is possible to carry out various separations. Moreover, it is easy to control the selectivity of the adsorption, and it is possible to meet various separation purposes.

According to the third to seventh aspects, a more excellent adsorption separation effect can be obtained. Such an adsorption separation method of the present invention is particularly effective for separating polycyclic aromatic or aliphatic isomer compounds.

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Claims (9)

[Claims] 1. A method for separating a target substance from a mixture of the target substance and an isomer of the target substance or other impurities, which comprises contacting the mixture with an adsorbent to obtain the adsorbent. In the method for desorbing the target substance from the adsorbent after adsorbing the target substance onto the adsorbent, a clay intercalation compound is used as the adsorbent. 2. A method for separating a target substance from a mixture of the target substance and an isomer of the target substance or other impurities, which comprises contacting the mixture with an adsorbent to obtain the adsorbent. In the method for adsorbing the isomer or other impurities to, to obtain only the target substance from the mixture, a clay intercalation compound is used as the adsorbent. 3. The adsorption separation method according to claim 1 or 2, wherein the adsorption treatment and the desorption treatment are performed in a liquid phase or a gas phase. 4. The method according to claim 1, 2 or 3,
A method for adsorption separation, wherein the clay intercalation compound is obtained by depositing a hydrolysis product of a metal salt in the pores of a clay-crosslinked porous body in which pillars of an inorganic substance are inserted between layers of a swelling clay mineral. 5. The method according to claim 4, wherein the clay intercalation compound is such that a hydrolysis product of a metal salt is deposited in pores of a clay-crosslinked porous body in which pillars of an inorganic substance are inserted between layers of a swelling clay mineral. An adsorption separation method characterized in that the porous body obtained by heating is heated to 100 to 800 ° C. 6. The method according to claim 1, 2 or 3, wherein
A method for adsorption separation, wherein the clay intercalation compound is formed by forming a composite with pillars of a pillar of a clay-crosslinked porous body in which pillars of an inorganic material are inserted between layers of a swelling clay mineral. 7. The method according to claim 6, wherein the clay intercalation compound is formed by forming a composite with pillars in a pillar of a clay-crosslinked porous body in which pillars of an inorganic material are inserted between layers of swelling clay minerals. An adsorption separation method characterized in that the body is heated to 100 to 800 ° C. 8. The adsorption separation method according to any one of claims 1 to 7, wherein the isomer is a polycyclic aromatic compound. 9. The adsorption separation method according to any one of claims 1 to 7, wherein the isomer is an aliphatic compound.