JPH09151139A - Separation and recovery of benzothiophere and naphthalene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a method for efficiently separating both the subject compounds from a mixture containing benzothiophene and naphthalene by a simple adsorption method using a specific adsorbent. SOLUTION: Benzothiophene and naphthalene are adsorbed and separated from a mixture containing the benzothiophene and the naphthalene, such as a distillate containing components having boiling points of 215-225 deg.C, which is obtained by distilling a coal tar, a coal-liquidized oil, a coal gasification distillate, etc., using faujasite type zeolite as an adsorbent. The adsorbent is preferably Y type faujasite, most preferably the Y type faujasite substituted with zinc, iron or nickel ions. The method enables to recover or purify either one of the benzothiophene and the naphthalene and further to separate, recover or purify both the compounds.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for separating or recovering benzothiophene and naphthalene from a mixture containing benzothiophene and naphthalene by an adsorption separation method.

[0002]

2. Description of the Related Art Benzothiophene is a substance useful as a raw material for synthesis of pharmaceuticals, agricultural chemicals and the like. This benzothiophene is contained in a fraction derived from high-temperature thermal decomposition of coal or petroleum, for example, coal tar fraction, fluid catalytic cracking oil, etc., and is particularly concentrated in residual oil obtained by recovering naphthalene from coal tar. Exist in large quantities. Further, although naphthalene is also a useful substance, there are many applications in which the presence of sulfur compounds as impurities is not desired.

However, benzothiophene (boiling point:
218 ° C.) and naphthalene (boiling point: 221 ° C.) are close to each other in boiling point, so that it is difficult to separate or recover each from a mixture by a distillation method which is a general-purpose separation technique. In addition, since benzothiophene and naphthalene form a eutectic, it is similarly difficult to employ a crystallization method which is an industrial separation technique.

Further, as a method of separating benzothiophene by an adsorption method, a method of using polyethylene glycol-supported alumina as an adsorbent (German Patent 7
2-2263992) or a method using silica gel carrying palladium chloride (Fuel, 1986, 65, p27).
0) and the like have been proposed, but the supporting metal is desorbed and eluted during the separation operation, and in either case, the separation efficiency is poor and it is not practical.

[0005]

An object of the present invention is to provide such a mixture comprising benzothiophene and naphthalene,
An object of the present invention is to provide an industrial method for efficiently separating or recovering both components.

[0006]

That is, the present invention provides a mixture containing benzothiophene and naphthalene,
Using faujasite type zeolite as an adsorbent,
A method for separating or recovering benzothiophene and naphthalene, characterized by adsorbing and separating both components.

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 represented by 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 one substituted 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.

Examples of the metal ion to be substituted are, for example,
Periodic table Ia of lithium, sodium, potassium, rubidium, cesium, etc., periodic table IIa of magnesium, calcium, strontium, barium, etc., periodic table IIb of zinc, etc., periodic table Ib of copper, silver, etc. One or more metal ions selected from the group consisting of Group VIII, Group VIII of the periodic table such as iron, cobalt and nickel, and rare earth elements such as yttrium, lanthanum and cerium.

Among these metal ions, preferred are ions of potassium, sodium, magnesium, calcium, strontium, barium, zinc, iron, cobalt, nickel and the like.

Particularly, as the adsorbent of the present invention, Y-type faujasite type zeolite substituted with zinc, iron or nickel ions is most preferable.

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.

Further, as the releasing agent used in the present invention,
Known elimination 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, n-butyl acetate, isopropyl acetate, isobutyl acetate, for example, ketones such as acetone, methyl ethyl ketone, n-propyl ketone, cyclohexanone, for example, methanol, ethanol, n-propyl alcohol, isopropyl alcohol , Alcohols such as n-butanol, for example, pyridines such as pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2,5-dimethylpyridine, and 2,6-dimethylpyridine, acetonitrile, aliphatic Hydrocarbons and aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, diethylbenzene, 1-methylnaphthalene, 2-methylnaphthalene, tetralin, decalin, ethylbiphenyl, and diethylbiphenyl. . Of these, aliphatic hydrocarbons and aromatic hydrocarbons are preferred, especially toluene,
Xylene, ethylbenzene, diethylbenzene, tetralin, decalin are most suitable.

The mixture containing benzothiophene and naphthalene has a boiling point of 215 to 225 obtained by distilling coal tar, coal liquefied oil, coal gasification distillate or the like.
Fractions containing components in the ° C range are included. Further, it may be one that is further distilled or crystallized to increase the concentration, or one obtained by another method. When benzothiophene or naphthalene is collected or purified, the concentration of the target substance is preferably increased. It is preferable that acidic components such as phenols and heavy components such as pitch be removed in advance.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION To adsorb and separate benzothiophene and naphthalene by using the adsorbent of the present invention, any of ordinary adsorption separation operation, batch separation method and continuous separation method can be applied. The industrial separation operation may be a so-called chromatographic separation method, or an adsorption separation method using a continuous simulated moving bed.

In the continuous adsorption separation method using a simulated moving bed, a plurality of adsorption towers are installed, adsorption, concentration, and desorption operations are performed in each tower, and these towers are sequentially switched to perform each operation. It is an industrial process of continuously performing.

First, a mixture containing benzothiophene and naphthalene or a feed material obtained by diluting the mixture with a diluent as necessary is brought into contact with a faujasite-type zeolite adsorbent to selectively adsorb strongly adsorbed components. , Weakly adsorbed components are separated as raffinate (adsorption operation).

Then, the raffinate rich in the weakly adsorbed component is further contacted with the adsorbent to adsorb the remaining strongly adsorbed component, and the weakly adsorbed component of the raffinate is concentrated (concentration operation).

Further, the strongly adsorbed component adsorbed is desorbed from the adsorbent by the desorbent and 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. Operating conditions include a temperature of room temperature to 350 ° C., preferably 50 to 150 ° C., and a pressure of atmospheric pressure to 10 ° C., depending on the type of the desorbent used and the type of the diluent used as necessary.
The range of MPa is preferable, and the range of atmospheric pressure to 5 MPa is preferable.

The present invention can be applied to recovering or purifying either benzothiophene or naphthalene, or separating, recovering or purifying both.

[0024]

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

[0025]

(Equation 1)

In Examples and Comparative Examples, α was calculated using naphthalene as the A component and benzothiophene 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 as α is larger than 1.0 or smaller than 1.0, the adsorption separation of the component A and the component B becomes easier.

Example 1 Commercially available Na-substituted Y-type faujasite zeolite (silica / alumina ratio: 5.5) was calcined at 350 ° C. for 3 hours,
Cooled in a dessicator. 10 g of this adsorbent and 50.1 g of the following liquid phase mixture were charged into a flask and the mixture was stirred at 50 ° C. for 3 hours.
It was shaken for a long time to make sufficient contact. The composition ratio of the charged liquid phase mixture was naphthalene: benzothiophene: n-pentadecane: isooctane = 2: 2: 46: 0.1 (weight ratio).

Then, the liquid phase mixture after contact with the adsorbent was analyzed by gas chromatography, and α was determined from its composition ratio. Isooctane was added as an internal standard substance for gas chromatography analysis. The results are listed in Table 1.

Example 2 In place 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. The results are listed in Table 1.

Examples 3 to 7 The Na-substituted Y-type faujasite zeolite of Example 1 was immersed in a 2N aqueous solution of nitrate or hydrochloride of metal ion to be exchanged at 95 ° C. for 3 hours. After repeating this operation twice, it was washed with water and dried at 120 ° C. Before use, it was calcined at 350 ° C. for 3 hours and cooled in a desiccator.
Thus, the M (Na) Y-type zeolite was prepared by partially substituting the metal ions (M ^{n +} ) to be exchanged by the ion exchange method. Using this as an adsorbent, an experiment was performed in the same manner as in Example 1. The results are listed in Table 1.

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. The results are listed in Table 1.

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. The results are listed in Table 1.

[0034]

[Table 1]

Comparative Examples 1 and 2 Instead of the Na-substituted Y-type faujasite zeolite of Example 1, a commercially available A-type zeolite (4A, powder) and Na were used.
An experiment was conducted in the same manner as in Example 1 using a substituted mordenite type zeolite (powder) as an adsorbent. The results are listed in Table 2.

[0036]

[Table 2]

* Mordenite type From Table 2, it can be seen that these zeolites are not practical because they have a small adsorption capacity and a low separation coefficient.

Example 10 An example of separating and recovering benzothiophene and naphthalene by using the adsorbent of the present invention with the residual oil obtained by recovering naphthalene from coal tar as a feedstock will be given. The composition of the naphthalene recovery residue oil of the feedstock is naphthalene 78.5.
%, Benzothiophene 18.9%, others 2.
It was 6% by weight.

In the same manner as in Example 4, Ni (N
a) Y-type zeolite (0.4 mmφ molded product) was prepared. 17 g of this zeolite is used for a tube inner diameter of 8 mm and a length of 50
It was packed in a 0 mm steel pipe to make an adsorption column. The column was kept at a temperature of 80 ° C., and para-xylene was used as a developing agent.
The column was filled with para-xylene by supplying at 5 ml / min.

Then, 5 g of a 25% by weight paraxylene solution of the feed material (adding 2% by weight of 1,3,5-triisopropylbenzene as an internal standard substance) was supplied to the column. Subsequently, para-xylene was supplied at a rate of 2.5 ml / min for 20 minutes, and the effluent was collected every 0.3 minutes and analyzed by gas chromatography. The results are shown in Figure 1.

In FIG. 1, the horizontal axis represents the outflow time (minutes),
The vertical axis represents the normalized concentration of each component. According to FIG. 1, it can be seen that benzothiophene and naphthalene are completely separated.

Further, samples having an outflow time of 12 to 18 minutes were collected, and paraxylene was distilled off to carry out dry weight measurement and component analysis. As a result, it was found that the sample having an outflow time of 12 to 18 minutes contained 93% by weight of benzothiophene and the recovery rate thereof was 99%.

[0043]

According to the separation and recovery method of the present invention, both components can be efficiently separated from a mixture containing benzothiophene and naphthalene by a simple adsorption method.
It is useful as a method for recovering or purifying benzothiophene and / or naphthalene.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the normalized concentration of each component in the effluent and the outflow time.

Claims (4)

[Claims] 1. A method for separating benzothiophene and naphthalene from a mixture containing benzothiophene and naphthalene using a faujasite-type zeolite as an adsorbent and adsorbing and separating both components. 2. The method for separating benzothiophene and naphthalene according to claim 1, wherein the adsorbent is Y-type faujasite-type zeolite. 3. A method for recovering benzothiophene and / or naphthalene, which comprises adsorbing and separating a mixture containing benzothiophene and naphthalene using a faujasite type zeolite adsorbent. 4. A method for purifying naphthalene, which comprises adsorbing and separating a mixture containing benzothiophene and naphthalene using a faujasite-type zeolite adsorbent.