JP2001335562A - Method for adsorbing and separating substituted pyridine compund - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently separating a specific substituted pyridine compound from a mixture comprising two or more pyridine compounds. SOLUTION: A zeolite is used as an adsorbent, and at least one kind of an amino compound selected from anilines, aliphatic amines and different substituted pyridines from the objective pyridine is used as a desorbent for the separation of the objective pyridine from the mixture comprising at lest the two or more substituted pyridine compounds by an adsorbing method. A mixture comprising at least two or more kinds of 2,6-dimethylpyridine, 3- methylpyridine and 4-methylpyridine is cited as the mixture of the substituted pyridine compounds as a concrete example.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for separating a specific substituted pyridine compound from a mixture containing at least two or more types of substituted pyridine compounds by an adsorption separation method. In particular, a fraction containing methylpyridines such as a coal tar fraction, particularly a mixture containing at least two or more of 2,6-dimethylpyridine, 3-methylpyridine and 4-methylpyridine is specified by an adsorption separation method. And a method for separating methylpyridine.

[0002]

2. Description of the Related Art Coke oven gas and coal tar derived from high-temperature carbonization of coal include pyridine, methylpyridines, and the like.
Organic bases such as quinoline, methylquinolines and isoquinoline are included. These organic bases are indispensable as raw materials for organic synthesis of pharmaceuticals, agricultural chemicals, etc., for example, after absorption from a coke oven gas with a sulfuric acid aqueous solution,
Cracking-by distillation and from coal tar-
It is recovered as a pyridine-containing fraction by acid extraction. Of these organic bases, methylpyridines are 2,
Recovered as a mixture of 6-dimethylpyridine, 3-methylpyridine and 4-methylpyridine.

However, 2,6-dimethylpyridine (boiling point: 143 to 145 ° C.), 3-methylpyridine (boiling point: 144 ° C.), 4-methylpyridine (boiling point: 145)
° C) is close to the boiling point, so it is difficult to separate the mixture from the mixture by distillation, which is a general-purpose separation technique.

As an industrial method for separating and recovering methylpyridines from a fraction containing methylpyridines such as a coal tar fraction, there is known an urea adduct method (A) (JP-A-58-74664). In this method, 2,6-dimethylpyridine is separated from a mixture of methylpyridines as a urea adduct, purified, and thermally decomposed with water in a specific solvent to obtain high-purity 2,6-dimethylpyridine.

[0005] Further, (B) a mixture of pyridine bases and a specific oxyflavan are mixed to form an inclusion complex with the specific bases, so that the boiling point of the mixture cannot be increased by distillation. A method of separating adjacent pyridine bases is also known (JP-A-61-85364).

Further, as a method for separating (C) methylpyridines by an adsorption method, basic adsorption data using silica-alumina as an adsorbent ("Resources and Environment" 199)
2, 1 (3), 201 to 207), a geometric isomer separation method using an ion exchange resin, silica, alumina, and aluminosilicate as an adsorbent (French Patent No. 2593409)
No.).

Then, there is a method of separating (D) faujasite-type zeolite as an adsorbent. (Japanese Patent Laid-Open No. 9-
No. 143162, Japanese Unexamined Patent Application Publication No. 10-25230, EP173440)

[0008]

However, in the method (A), the recovery rate is limited because 2,6-dimethylpyridine and water azeotrope, and 3-methylpyridine and 4-methylpyridine are not azeotropic.
Methylpyridine is obtained only as a mixture. Also,
Both (B) and (C) have poor separation efficiency and are industrially less practical. Further, in the method (D), n-pentadecane, a hydrocarbon of isooctane, and a heterocyclic compound of pyridine are used as a desorbent in the presence of a faujasite-type zeolite. Does not exhibit the proper desorption performance required for this purpose. Therefore,
Separation efficiency deteriorates.

Accordingly, an object of the present invention is to provide a method for efficiently separating a specific substituted pyridine compound from a mixture containing at least two or more substituted pyridine compounds by an adsorption separation method.

[0010]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a mixture containing at least two substituted pyridine compounds can be desorbed using zeolite as an adsorbent. Anilines,
It has been found that a specific pyridine compound can be efficiently separated by using at least one selected from aliphatic amines and substituted pyridines different from the object to be separated, leading to the present invention.

That is, the present invention provides a method for separating a specific substituted pyridine compound from a mixture containing at least two or more substituted pyridine compounds by an adsorption separation method, wherein zeolite is used as an adsorbent; A method for adsorptive separation of a substituted pyridine compound, characterized by using at least one selected from anilines, aliphatic amines and substituted pyridines different from the object to be separated. "

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The substituted pyridine compound to be separated in the present invention includes α-picoline, β-picoline, γ-picoline, 3,5-lutidine, 2,6-lutidine, 2,4-lutidine, 2,
5-lutidine, 3,4-lutidine, 2,3-lutidine, 2,4,6-collidine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2-vinylpyridine, 3-vinylpyridine, 4 -Vinylpyridine, 2-pyridinemethanol, 3-pyridinemethanol, 4-pyridinemethanol, 2-aminopyridine, 3-
Aminopyridine, 4-aminopyridine, 2-dimethylaminopyridine, 3-dimethylaminopyridine, 4-dimethylaminopyridine, 2-aldehydepyridine, 3-aldehydepyridine, 4-aldehydepyridine, nicotinic acid, isonicotinic acid, picolinic acid , 2-chloropyridine, 3-chloropyridine, 4-chloropyridine, 3,5-dichloropyridine, 2,6-dichloropyridine, 2,4-dichloropyridine, 2,5-dichloropyridine, 3,4-dichloropyridine , 2,3-dichloropyridine, 2-cyanopyridine, 3-cyanopyridine, 4-cyanopyridine, 2-chloro-5-methylpyridine, 2-chloro-4-methylpyridine, 2-chloro-3-methylpyridine, 2-chloro-6-
Methyl pyridine and the like can be mentioned.

[0013] The zeolite used in the present invention is described in W. M. WM Meier, De. H. The book "Atlas Obzeolites Structure Types (ATLAS) by DH Olson et al.
OF ZEOLITE STRUCTURE TYPES) "(Zeolites 17,1 / 2,199
6; Elsevier Co., Ltd.), but any of the structures described in detail is preferable, but the faujasite type, MFI type, mordenite type and beta type are more preferable, and the faujasite type is more preferable. Zeolites are preferred.

The zeolite used in the present invention is
A so-called isomorphous zeolite in which part of silica (silicon), which is a component of zeolite, is replaced by germanium, or part of aluminum is replaced by gallium, chromium, iron, or the like, may be used.

The zeolite used in the present invention is:
A synthesized product may be used, or a commercially available product may be used. When a synthesized product is used, zeolite can be synthesized by a known method. For example, the synthesis method of faujasite type zeolite is disclosed in JP-B-52-1540.
No. 0, U.S. Pat. No. 2,882,244, U.S. Pat. No. 3,130,007, etc., and a method for synthesizing beta zeolite is disclosed in U.S. Pat.
No. 08,069 and Japanese Patent Publication No. 7-223989, and a method for synthesizing a mordenite-type zeolite is disclosed in, for example, Japanese Patent Publication No. 47-46677 and Japanese Patent Application Laid-Open No.
No. 26529, Japanese Patent Publication No. 2-31006 and the like, and the synthesis method of MFI type zeolite is described in, for example, US Pat. No. 3,702,886 and US Pat. No. 4,511,547. , Tokiko 60-3528
No. 4 and the like.

The faujasite-type zeolites preferably used in the present invention are X-type zeolites and Y-type zeolites, which are crystalline aluminosilicates represented by the following formula.

0.9 ± 0.2 M _{2 / n} O: Al ₂ O ₃ : xS
iO ₂ : yH ₂ O where M represents a cation and n represents its valence. In the faujasite-type zeolite, x in the above formula is usually in the range of 2 to 6. The faujasite-type zeolite is an X-type zeolite in which x is 2-3, and x
Are classified into Y-type zeolites having 3 to 6. Also y
Depends on the degree of hydration.

In the present invention, a zeolite containing at least one cation selected from an alkali metal, an alkaline earth metal and silver is preferably used, and more preferably a silver cation. Examples of the alkali metal include lithium, sodium, potassium, cesium, rubidium and the like, and examples of the alkaline earth metal include magnesium, calcium, strontium and barium.

The exchangeable cation in the zeolite can be replaced by various cations by ion exchange.
The cation exchange method is usually carried out by bringing zeolite into contact with an aqueous solution of a compound containing a desired cation, for example, a hydrochloride, nitrate, sulfate, carbonate, hydroxide or the like. The amount of ion exchange varies depending on the type of cation, but can be arbitrarily set depending on the concentration of the aqueous solution.
In particular, silver ions are preferably exchanged with an aqueous solution containing silver equivalent to 0 to 50% of the ion exchange sites, and more preferably exchanged with an aqueous solution containing silver equivalent to 2 to 20%. After the ion exchange, the substrate is sufficiently washed with water to remove sodium ions, for example, chloride ions and nitrate ions, which have been exchanged and eluted in the aqueous solution.

Further, the adsorbent used in the present invention may be a solidified zeolite alone or a granulated with a binder such as silica, alumina, silica-alumina, magnesia or clay mineral.

The zeolite used in the present invention may be used as a mixture of two or more zeolites, if necessary.

It is preferable that the adsorbent removes water of crystallization in the zeolite before use. Usually 200 to 60
By heating at 0 ° C., most of the crystallization water can be removed.

The adsorption separation technique for adsorbing and separating a specific substituted pyridine compound from a mixture containing at least two substituted pyridine compounds using the adsorbent of the present invention may be a so-called chromatographic preparative method. Alternatively, an adsorption / separation method using a simulated moving bed in which this is continuous may be used.

The continuous adsorption / separation technique using a simulated moving bed is carried out as a basic operation by continuously circulating the following adsorption operation, concentration operation and desorption operation. (1) Adsorption operation: A raw material feed containing a mixture containing at least two or more substituted pyridine compounds is brought into contact with the adsorbent of the present invention, and the strongest adsorbed component is selectively adsorbed. The strongest adsorbed component is recovered as an extract component together with a desorbing agent described later. (2) Concentration operation: The raffinate containing a large amount of weakly adsorbed components is further contacted with an adsorbent, and the strongest adsorbed components are selectively adsorbed, so that the weakly adsorbed components in the raffinate are highly purified. (3) Desorption operation: The highly purified weakly adsorbed component is recovered as raffinate, while the strongest adsorbed component is expelled from the adsorbent by the desorbent and recovered as an extract component with the desorbent. .

As the desorbing agent used in the above-mentioned adsorption separation method, it is essential to use at least one selected from anilines, aliphatic amines and substituted pyridines different from those to be separated. More preferred are anilines.

Specific examples of anilines include aniline,
Examples include methylaniline, dimethylaniline, diphenylamine, triphenylamine, toluidine, anisidine, chloroaniline, bromoaniline, nitroaniline, dinitroaniline, trinitroaniline, and phenylenediamine.

Specific examples of the aliphatic amines include methylamine, dimethylamine, ethylamine, triethylamine, n-propylamine, di-n-propylamine,
Tri-n-propylamine, isopropylamine, n-
Butylamine, isobutylamine, sec-butylamine,
tert-butylamine, cyclohexylamine, benzylamine, α-phenylethylamine, β-phenylethylamine, ethylenediamine, tetramethylenediamine,
Hexamethylenediamine, piperazine, piperidine, pyrrolidine and the like can be mentioned.

Specific examples of substituted pyridines different from those to be separated include picoline, chloropyridine, bromopyridine, aminopyridine, nitropyridine, ethylpyridine, lutidine and the like. In this case, they are contained in the liquid to be separated. Must be different from the substituted pyridine compound used.

When separating a mixture of methyl-substituted pyridine compounds, it is preferable to use anilines as a desorbing agent.

These desorbing agents may be used alone or as a mixture.

As operating conditions for the adsorption separation method, the temperature is preferably from room temperature to 350 ° C., and more preferably from 50 to 350 ° C.
The temperature is 250 ° C., and the pressure is preferably from atmospheric pressure to 4 MPa, more preferably from atmospheric pressure to 3 MPa. Although the adsorption separation process of the present invention can be carried out in the gas phase, it is preferably carried out in the liquid phase to reduce the operating temperature and reduce undesired side reactions of the feedstock or desorbent.

Generally, to express the adsorption characteristics of an adsorbent,
The adsorption selectivity (α) of the following equation (1) is used.

[0033]

(Equation 1)

Here, A and B represent any one of the substituted pyridine compounds, S represents an adsorption phase, and L represents a liquid phase in equilibrium with the adsorption phase.

If the value α _{A / B in the} above equation is 1.0, A, B
There is no selective adsorption between components. When α _{A / B} is larger than 1.0, the component A is selectively adsorbed, and when α _{A / B} is smaller than 1, the component B is selectively adsorbed. In the above formula, the adsorbent having α _{A / B} larger than 1 (or the adsorbent having α _{A / B} smaller than 1 and close to 0) becomes easier to adsorb and separate A and B.

The adsorption rate is calculated using the following equation (2).

[0037]

(Equation 2)

[0038]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

(Preparation of adsorbent) A list of adsorbents used is shown in Table 1.
Shown in The preparation method will be described later. Adsorbent 1: Na-Y Sodium type Y-type zeolite (hereinafter referred to as Na-Y) (manufactured by Toso Co., Ltd., Zeolam Na-5.1Y powder) 100 parts by weight of alumina sol (Nissan Chemical) as a binder No. 200; Al ₂ O ₃ = 10 wt%) was added in an amount of 15 parts by weight in terms of alumina, and NaY-type zeolite granulated to 0.15 to 0.5 mmφ was dried at 120 ° C.
C. for 2 hours. Adsorbent 2: Na-X sodium type X zeolite (hereinafter referred to as Na-X) (Zeolam F-9 powder product, manufactured by Tosoh Corporation) 10
20 parts by weight of bentonite gel (Bengel) was added as a binder to 0 parts by weight, and the NaX-type zeolite granulated to 0.15 to 0.3 mmφ was dried at 120 ° C.
C. for 2 hours. Adsorbent 3: Ag-Na-Y Using an aqueous silver nitrate solution (in terms of moles of metal) corresponding to 50% of the Na cation sites of Na-Y (adsorbent 1) (solid-liquid ratio: 3.0 L / kg) at room temperature for 30 days For 1 hour at 85 ° C., and after washing thoroughly with distilled water,
C., and baked for 2 hours at 500.degree. Adsorbent 4: Ag-Na-X Using a silver nitrate aqueous solution (in terms of moles of metal) corresponding to 50% of the Na cation site of Na-X (adsorbent 2) (solid-liquid ratio: 3.0 L / kg) at room temperature for 30 days For 1 hour at 85 ° C., wash thoroughly with distilled water,
It was dried at 0 ° C. and calcined at 500 ° C. for 2 hours.

(Adsorption Experiment) Example 1 α-picoline: β-picoline: 2,6-lutidine: 2,4
A raw material was prepared by mixing lutidine: n-nonane = 1: 1: 1: 1: 1 (weight ratio). To this, 50 parts by weight of aniline based on the raw material was added as a desorbing agent. In addition,
n-Nonane is a substance which is added as an internal standard substance in the gas chromatography method and is substantially inert to adsorption in the above experiment. 2. Baking with 2.7 ml of the liquid phase mixture for 2 hours at 500 ° C. in an autoclave having an inner volume of 5 ml.
3 ml of the adsorbent 3 was filled and left at 150 ° C. for 1 hour with occasional stirring. The composition of the liquid phase mixture after contact with the adsorbent was analyzed by gas chromatography, and the adsorption selectivity (α) and the adsorption rate (C) were determined using the above formulas (1) and (2).

Example 2 The procedure of Example 1 was repeated, except that the adsorbent was changed from the adsorbent 3 to the adsorbent 4.

Example 3 The same operation as in Example 1 was carried out except that the desorbent was changed from aniline to o-toluidine.

Example 4 An experiment was carried out in the same manner as in Example 3, except that the adsorbent was changed from the adsorbent 3 to the adsorbent 4.

Example 5 The same operation as in Example 1 was carried out except that the desorbent was changed from aniline to p-toluidine.

Example 6 An experiment was carried out in the same manner as in Example 5 except that the adsorbent was changed from the adsorbent 3 to the adsorbent 4.

Comparative Example 1 The same procedure was performed as in Example 2 except that the desorbing agent was changed from aniline to pyridine.

Table 1 shows the results.

[0048]

[Table 1]

When 2,6-lutidine is separated as a raffinate, α _{2,4 / 2,6} is smaller than 1.0 in Comparative Example 1, and separation is not possible. On the other hand, when aniline or toluidine was used as the desorbing agent, the separation coefficient α was all larger than 1.0, and the value was also higher than when pyridine of the comparative example was used as the desorbing agent.

[0050]

According to the present invention, a mixture containing at least two or more substituted pyridine compounds can be separated by adsorption by a separation method.
A specific substituted pyridine compound can be efficiently separated.

Claims (7)

[Claims] When separating a specific substituted pyridine compound from a mixture containing at least two or more substituted pyridine compounds by an adsorption separation method, zeolite is used as an adsorbent, and anilines and fats are used as desorbents. A method for adsorptive separation of a substituted pyridine compound, comprising using at least one selected from aromatic amines and substituted pyridines different from the separation target. 2. The method according to claim 1, wherein the substituted pyridine compound to be separated is an alkyl group-substituted pyridine compound. 3. The method according to claim 2, wherein the alkyl group-substituted pyridine compound to be separated is a methyl group-substituted pyridine compound. 4. The method for adsorbing and separating a substituted pyridine compound according to claim 1, wherein the desorbing agent is an aniline. 5. The zeolite according to claim 1, wherein the zeolite is a zeolite containing at least one cation selected from alkali metals, alkaline earth metals and silver.
The method for adsorptive separation of a substituted pyridine compound according to any one of the above. 6. The method for adsorptive separation of a substituted pyridine compound according to claim 5, wherein the zeolite contains a silver cation. 7. The zeolite according to claim 1, wherein the zeolite is at least one zeolite selected from faujasite type, mordenite type, beta type and MFI type.
7. The method for adsorptive separation of a substituted pyridine compound according to any one of 6.