JPH09143162A - Method for separating methylpyridines - Google Patents

Abstract

(57) Abstract: Provided is an industrial method for efficiently separating and recovering methylpyridines from a fraction containing methylpyridines, particularly a mixture of two or more kinds of methylpyridine isomers and dimethylpyridine. SOLUTION: A faujasite-type zeolite is used as an adsorbent in a method for recovering methylpyridines from a methylpyridine-containing fraction by an adsorption separation method. As the faujasite-type zeolite, Y-type faujasite-type zeolite substituted with sodium, magnesium, nickel or iron ions is preferable. [Effect] 3-methylpyridine, 4-methylpyridine, and 2,6-dimethylpyridine can be efficiently separated and recovered from the methylpyridine-containing fraction.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fraction containing methylpyridines such as a coal tar fraction, and particularly to at least two kinds of 2,6-dimethylpyridine, 3-methylpyridine and 4-methylpyridine. The present invention relates to a method of separating and recovering methylpyridines from a mixture by an adsorption method.

[0002]

BACKGROUND ART Coke oven gas and coal tar derived from high temperature carbonization of coal include pyridine, methylpyridines,
Organic bases such as quinoline, methylquinolines and isoquinoline are included. These organic bases are indispensable as a raw material for organic synthesis of pharmaceuticals, agricultural chemicals, etc., for example, after absorption from a coke oven gas with a sulfuric acid aqueous solution,
Decomposition-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)
Since the boiling points of (.degree. C.) are close to each other, it is difficult to separate them from the mixture by a distillation method which is a general-purpose separation technique.

The urea adduct method is known as an industrial method for separating and recovering methylpyridines from a methylpyridine-containing fraction such as coal tar fraction (Japanese Patent Laid-Open No. 58-58).
-74664 gazette). In this method, 2,6-dimethylpyridine is separated from a mixture of methylpyridines as a urea adduct, purified, and then thermally decomposed with water in a specific solvent to obtain highly pure 2,6-dimethylpyridine. But,
Since 2,6-dimethylpyridine and water are azeotropically distilled, the recovery rate is limited, and 3-methylpyridine and 4-methylpyridine can be obtained only as a mixture.

Further, a specific oxyflavane is mixed with a mixture of pyridine bases to form an inclusion complex with the specific bases, and pyridine having a boiling point close to that which is impossible by the distillation method. A method for separating bases is also known (Japanese Patent Laid-Open No. 61-85364).

Further, as a method for separating methylpyridines by an adsorption method, basic adsorption data using silica-alumina as an adsorbent (“Resources and Environment” 1992, 1
(3), 201-207) or an ion exchange resin for the adsorbent,
There is a geometric isomer separation method (French Patent No. 2593409) using silica, alumina, and aluminosilicate, but all of them have poor separation efficiency and are industrially low in practicality.

[0007]

DISCLOSURE OF THE INVENTION The object of the present invention is to obtain methylpyridine-containing fractions, especially 2,6-dimethylpyridine,
An object of the present invention is to provide an industrial method for efficiently separating and recovering methylpyridines from a mixture containing at least two kinds of 3-methylpyridine and 4-methylpyridine.

[Means for Solving the Problems]

That is, the present invention is a method for separating methylpyridines from a methylpyridine-containing fraction by an adsorption separation method, in which a faujasite-type zeolite is used as an adsorbent,
The separation method is preferably a Y-type faujasite-type zeolite as an adsorbent, and more preferably a Y-type faujasite-type zeolite substituted with sodium, magnesium, nickel or iron ions.

The adsorbent used in the present invention is a faujasite type zeolite. The faujasite-type zeolite is a crystalline aluminosilicate represented by the following formula. 0.9 ± 0.2 M _{2 / n} O: Al ₂ O ₃ : xSiO ₂ : y
H ₂ O Here, M represents a cation and n represents its valence.
The faujasite-type zeolite of the above formula includes X-type and Y-type, X-type is x = 2 to 3, Y-type is x = 3 to 6, and y varies depending on the degree of hydration.

In the present invention, of the faujasite type zeolites, the Y-type faujasite type zeolite is the preferred adsorbent.

The faujasite-type zeolite used in the present invention may be of the hydrogen ion or ammonium ion type, but is preferably replaced with one or more metal ions. The amount of metal ion substitution is not limited, and part or all of the cations may be substituted. It is preferably 10% or more.

The metal ions to be substituted include, for example,
Sodium, potassium, silver, calcium, strontium, barium, zinc, lead, cerium, magnesium,
Examples include ions of copper, aluminum, zirconium, vanadium, molybdenum, manganese, iron, cobalt, nickel, platinum and the like.

Of these, Periodic Tables Ia, IIa, II
A metal ion selected from groups b, IIIa and VIII is preferable, and examples thereof include ions of potassium, sodium, magnesium, calcium, strontium, barium, zinc, iron, cobalt and nickel.

Particularly, as the adsorbent of the present invention, the Y-type faujasite type zeolite substituted with sodium, magnesium, nickel or iron ions is most preferable. These zeolites may be commercially available sodium Y-type zeolites themselves, or may be Y-type zeolites obtained by substituting them with magnesium, nickel or iron ions.

The ion exchange method for these cations is carried out by bringing the zeolite into contact with a water-soluble salt of an ion to be exchanged, for example, an aqueous solution of hydrochloride, nitrate, sulfate, carbonate or the like. The metal ion concentration of the aqueous solution varies depending on the type of the metal salt, but is preferably about 1 to 10% by weight. The method may be a batch type or a flow type. The contact may be repeated several times as necessary. The temperature at this time may be about 20 to 100 ° C. The ion exchange amount varies depending on the type of ions, but can be arbitrarily set depending on the concentration of the solution, the temperature at the time of ion exchange, and the like.

Y-type zeolite and X used in the present invention
The shape of the type zeolite is appropriately selected according to the method of contacting the substance to be separated and the zeolite, and may be a compression molded product, a molded product by spray drying, or a powder.

As the releasing agent used in the present invention, known releasing agents can be used. For example, ethers such as diethyl ether, isopropyl ether, n-propyl ether and anisole, for example, ethyl acetate. ,
Esters such as n-propyl acetate, isopropyl acetate, n-butyl acetate and isobutyl acetate, for example, ketones such as acetone, methyl ethyl ketone, n-propyl ketone and cyclohexanone, for example, methanol, ethanol, n-propyl alcohol, isopropyl alcohol , N-butanol and other alcohols, for example, pyridine, quinoline, 2-methylquinoline, 8-methylquinoline, dimethylquinoline and other organic bases, and acetonitrile and the like. Of these, esters, alcohols, pyridine and alkylquinolines, acetonitrile and the like are preferable, and ethyl acetate, butyl acetate, methanol, isopropyl alcohol, pyridine, quinoline, and acetonitrile are particularly preferable.

Fractions containing methylpyridine include 2,6
-It is sufficient that at least two or more of dimethylpyridine, 3-methylpyridine and 4-methylpyridine are contained, but preferably, acid extraction and distillation from coal tar, coke oven gas, tar gas oil, coal liquefied oil and the like. It is a fraction containing components having a boiling point in the range of 140 to 150 ° C., which is recovered through such operations. It is desirable to remove acidic components such as phenols and heavy components such as pitch in advance.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The method for adsorptive separation of methylpyridines by the method of the present invention may be a chromatographic preparative method or a continuous adsorptive separation method using a simulated moving bed.

The continuous adsorption separation method using a simulated moving bed is as follows:
This is an industrial process in which a plurality of adsorption towers are installed and the adsorption, concentration, and desorption operations are carried out in each tower, and these towers are sequentially switched to carry out each operation continuously. First, a methylpyridine-containing fraction or a feedstock diluted with a diluent as necessary is contacted with a faujasite-type zeolite adsorbent to selectively adsorb strongly adsorbed components, while weakly adsorbed components as raffinate. Separate (adsorption operation). Next, the raffinate rich in weakly adsorbed components is further contacted with an adsorbent to adsorb the remaining strongly adsorbed components, and the weakly adsorbed components of the raffinate are concentrated (concentration operation). Further, the strongly adsorbed component that has been adsorbed is desorbed from the adsorbent by the desorbent, and is recovered as an extract together with the desorbent (desorption operation).

The adsorption / separation operation of the present invention can be carried out either in the gas phase or in the liquid phase, but it is preferable to carry out in the liquid phase because lowering the temperature can suppress side reactions. As operating conditions, the temperature is from room temperature to 350 ° C., preferably 5
The pressure is preferably from 0 to 250 ° C. and the pressure is from atmospheric pressure to 50 kg / cm ² · G.

[0022]

The present invention will be described in detail below with reference to examples. In Examples and Comparative Examples, the adsorption characteristics were determined according to the following (1).
It is represented by the separation coefficient α in the equation.

[0023]

(Equation 1)

In the following Examples and Comparative Examples, α was calculated using 4-methylpyridine as the A component and 2,6-dimethylpyridine as the B component. Also, the amounts of each component are based on weight.

In equation (1), if α is 1.0,
There is no selective adsorption between A and B components. Α is 1.0
If it is larger, the component A is selectively adsorbed, and if it is smaller than 1.0, the component B is selectively adsorbed. Therefore, it can be seen that the more the α is larger than 1.0 or smaller than 1.0, the easier the separation and separation of the A component and the B component are from the A component and the B component.

Example 1 Commercially available Na-substituted Y-type faujasite zeolite (silica / alumina ratio: 5.5) was calcined at 350 ° C. for 4 hours,
Cooled in a dessicator. 10 g of this adsorbent and 5 raw materials
0.1 g was placed in a flask and shaken at 50 ° C. for 3 hours to bring them into sufficient contact. The composition ratio of the raw materials is 2,6-dimethylpyridine: 4-methylpyridine: n-pentadecane:
Isooctane = 2: 2: 46: 0.1 (weight ratio). Then, the product obtained by the adsorption operation is analyzed by gas chromatography, and from the composition ratio, α of the formula (1) is calculated.
I asked. Isooctane was added as an internal standard substance for gas chromatography analysis. Table 1 shows the results.

Example 2 Instead of the Na-substituted Y-type faujasite zeolite of Example 1, a commercially available K-substituted Y-type faujasite zeolite (silica / alumina ratio: 5.7) was used as an adsorbent. The experiment was conducted in the same manner as in Example 1. Table 1 shows the results.

Example 3 Fe (Na) Y type zeolite was prepared by partially substituting sodium in the Na-substituted Y type faujasite zeolite of Example 1 with iron ions by an ion exchange method. Using this as an adsorbent, an experiment was performed in the same manner as in Example 1. Table 1 shows the results.

Example 4 Ni (Na) Y type zeolite was prepared by partially substituting sodium in the Na-substituted Y type faujasite zeolite of Example 1 with nickel ions by an ion exchange method. Using this as an adsorbent, an experiment was performed in the same manner as in Example 1. Table 1 shows the results.

Example 5 Ag (Na) Y type zeolite was prepared by partially substituting sodium of the Na-substituted Y type faujasite zeolite of Example 1 with silver ions by an ion exchange method. Using this as an adsorbent, an experiment was performed in the same manner as in Example 1. Table 1 shows the results.

Example 6 A Zn (Na) Y type zeolite was prepared by partially substituting sodium of the Na-substituted Y type faujasite zeolite of Example 1 with zinc ions by an ion exchange method. Using this as an adsorbent, an experiment was performed in the same manner as in Example 1.
Table 1 shows the results.

Example 7 A Mg (Na) Y type zeolite was prepared by partially substituting sodium in the Na-substituted Y type faujasite zeolite of Example 1 with magnesium ions by an ion exchange method. Using this as an adsorbent, an experiment was performed in the same manner as in Example 1. Table 1 shows the results.

Example 8 In place of the Na-substituted Y-type faujasite zeolite of Example 1, a commercially available HY-type faujasite zeolite (silica / alumina ratio: 5.6) was used as an adsorbent. An experiment was conducted in the same manner as in. Table 1 shows the results.

Example 9 Instead of the Na-substituted Y-type faujasite zeolite of Example 1, a commercially-available Na-substituted X-type faujasite zeolite (silica / alumina ratio: 2.5) was used as an adsorbent. The experiment was conducted in the same manner as in Example 1. Table 1 shows the results.

Comparative Example The same experiment as in Example 1 was conducted using a commercially available Na-substituted mordenite type zeolite as an adsorbent instead of the Na-substituted Y type faujasite zeolite of Example 1. Table 1 shows the results.

[0036]

[Table 1]

Example 10 A commercially available Na-substituted Y-type faujasite zeolite was used as 35
It was calcined at 0 ° C. for 4 hours and cooled in a desiccator. Charge 10 g of this adsorbent and 50.1 g of raw material into a flask, and
The plate was shaken at 0 ° C. for 3 hours to make sufficient contact. The composition ratio of the raw materials was 2,6-dimethylpyridine: 4-methylpyridine: 3-methylpyridine: n-pentadecane: isooctane = 2: 2: 2: 44: 0.1 (weight ratio).
Then, the product obtained by the adsorption operation was analyzed by gas chromatography, and α in the formula (1) was determined from the composition ratio. Table 2 shows the results.

[0038]

[Table 2]

[0039]

According to the separation method of the present invention, 3-methylpyridine, 4-methylpyridine and 2,6-dimethylpyridine are extracted from a methylpyridine-containing fraction, particularly a mixture of methylpyridine isomers and dimethylpyridine. , Each can be efficiently separated.

Claims (3)

[Claims] 1. A method for separating methylpyridines from a methylpyridine-containing fraction by an adsorption separation method, wherein a faujasite-type zeolite is used as an adsorbent, the method for separating methylpyridines. 2. The method for separating methylpyridines according to claim 1, wherein the adsorbent is Y-type faujasite zeolite. 3. The adsorbent is sodium, magnesium,
The method for separating methylpyridines according to claim 1, which is a Y-type faujasite-type zeolite substituted with nickel or iron ions.