JP2000229892A - Separation and collection of benzothiophene and naphthalene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separation and collection method capable of effectively separating naphthalene and benzothiophene from a mixture including both components in a simple absorbing method and capable of separating components having resembling boiling point such as dimethylindane or the like at the same time. SOLUTION: In this absorption and separation of both components from the mixture including benzothiophene and naphthalene, a β-type zeolite is used as the absorbent in the absorption and separation. The β-type zeolite obtained by ion exchanging with metals belonging to Ia or IIa groups of the periodic system is preferred, and a 6-12C aliphatic hydrocarbon or 6-10C aromatic hydrocarbon are used as a desorbing agent in the absorption and separation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating or recovering benzothiophene and naphthalene from a mixture containing benzothiophene and naphthalene by adsorption separation.

[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 fractions derived from high-temperature pyrolysis of coal and petroleum, for example, coal tar fractions, fluid catalytic cracking oils, etc., and is particularly concentrated in residual oil obtained by recovering naphthalene from coal tar. Present in large quantities. Naphthalene is also a useful substance, but there are many uses where it is not desired that a sulfur compound is present as an impurity.

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. Further, since benzothiophene and naphthalene form a solid solution, it is similarly difficult to carry out crystallization, which is an industrial separation technique.

Further, as a method of separating benzothiophene by adsorption separation, a method using polyethylene glycol-supported alumina as an adsorbent (German Patent No. 7)
However, polyethylene glycol elutes during the separation operation, resulting in poor separation efficiency. In addition, a method using palladium chloride-supported silica gel (F
uel, 1986, 65, p270), but the supported metal is desorbed and eluted, resulting in poor separation efficiency.
Both have practical problems.

On the other hand, a method using a metal-exchanged zeolite X as an adsorbent (Koks. Khimm, 1985, 8,
p35, USSR1174424), a method using a faujasite-type zeolite such as a method using a metal-exchanged Y-type zeolite (Japanese Unexamined Patent Publication No. 9-151139) is excellent in the performance of separating both, but the residual oil and the like In some cases, separation of impurities mixed in trace amounts is not sufficient.
In such a case, an operation for removing trace impurities may be necessary before or after the adsorption separation.

[0006]

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.

[0007]

That is, the present invention is characterized in that when separating and adsorbing both components from a mixture containing benzothiophene and naphthalene, a beta-type zeolite is used as an adsorbent. It is a separation and recovery method. The term “separation / recovery” shall mean not only the separation between the two but also the purification, separation or recovery of either or one of them.

[0008] The adsorbent used in the present invention is a beta zeolite. Beta zeolite is a crystalline aluminosilicate known in U.S. Pat. No. 3,308,089. Its characteristic is that it is a kind of so-called high silica zeolite with high silica / alumina ratio,
It has a relatively large pore diameter having a 12-membered ring structure, a channel having a unique three-dimensional network structure, and the like. Table 1 shows an example of the plane spacing of beta zeolite and the relative intensity of the diffraction line obtained by X-ray diffraction.

[0009]

[Table 1]

The silica / alumina ratio of the beta zeolite used in the present invention is not particularly limited, but is usually 20 to
200, preferably 25 to 150. The beta zeolite may be of the hydrogen ion or ammonium ion type, but is preferably one substituted with one or more metal ions. Then, part or all of the ion exchange site may be replaced. The substitution rate is preferably 10% or more.

The metal ions to be substituted include lithium,
Group Ia periodic table of sodium, potassium, rubidium, cesium, etc. or Periodic table IIa of beryllium, magnesium, calcium, strontium, barium, etc.
Group metal ions are preferred.

The method of ion exchange of these cations is carried out by bringing zeolite into contact with an aqueous solution of a water-soluble salt of the ion to be exchanged, for example, 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 amount of ion exchange varies depending on the type of ion, but can be arbitrarily set depending on the concentration of the solution, the temperature at the time of ion exchange, and the like.

The shape of the zeolite used in the present invention is as follows:
It is appropriately selected according to the method of contacting the mixture containing benzothiophene and naphthalene with zeolite, and may be a compression molded product, a molded product by a spray dryer or the like, or a powder.

As the desorbing agent used in the adsorption separation, a known desorbing agent can be used, for example, ethers such as diethyl ether, isopropyl ether, n-propyl ether, anisole, and the like. Esters such as ethyl acetate, n-propyl acetate, n-butyl acetate, isopropyl acetate and isobutyl acetate, for example, ketones such as acetone, methyl ethyl ketone, n-propyl ketone and cyclohexanone, for example, methanol, ethanol, n-propyl Alcohols such as alcohol, isopropyl alcohol and n-butanol, for example, pyridine, 2-methylpyridine, 3-methylpyridine,
Methylpyridine, 2,5-dimethylpyridine, 2,6-
Pyridines such as dimethylpyridine, acetonitrile, for example, hexane, octane, cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, isopropylcyclohexane, decalin, aliphatic hydrocarbons such as bicyclohexyl, for example, benzene, toluene, xylene, ethylbenzene And aromatic hydrocarbons such as isopropylbenzene, diethylbenzene, 1-methylnaphthalene, 2-methylnaphthalene, tetralin, ethylbiphenyl and diethylbiphenyl.

Of these, aliphatic hydrocarbons and aromatic hydrocarbons are preferred, and particularly, C ₆ to C ₁₀ aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, isopropylbenzene, diethylbenzene, hexane, heptane, and the like. Most preferred are C ₆ to C ₁₂ aliphatic hydrocarbons such as octane, isooctane, nonane, decane, cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, isopropylcyclohexane, decalin, bicyclohexyl and the like.

The mixture containing benzothiophene and naphthalene has a boiling point of 215 to 225 obtained by distilling coal tar, coal liquefied oil, coal gasified distillate and the like.
Fractions containing components in the ° C range. This was further distilled and crystallized. The concentration may be increased, or may be obtained by another method.

When benzothiophene or naphthalene is recovered or purified, the concentration of the target compound is preferably increased. It is preferable that acidic components such as phenols and heavy components such as pitch be removed in advance.

[0018]

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 or continuous separation method can be applied. As an industrial separation operation, a so-called chromatographic preparative method may be used, or an adsorptive separation method using a simulated moving bed in which this is continuous may be used.

In the continuous adsorption separation method using a simulated moving bed, a plurality of adsorption columns are installed, and the operations of adsorption, concentration and desorption are performed in each column, and these columns are sequentially switched to obtain the following. This is an industrial process in which such operations are continuously performed.

First, a mixture containing benzothiophene and naphthalene or a feedstock obtained by diluting the mixture with a diluent as required is brought into contact with a beta-type zeolite adsorbent,
Strongly adsorbed components are selectively adsorbed, while weakly adsorbed components are separated as raffinates (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 adsorbed strongly adsorbed component is desorbed from the adsorbent by a desorbing agent, and recovered together with the desorbing agent as an extract (desorption operation).

The adsorption / separation operation of the present invention can be carried out in either a gas phase or a liquid phase. However, it is preferable to carry out the adsorption / separation operation in a liquid phase because a lower temperature can suppress side reactions. As operating conditions, the temperature ranges from room temperature to 200 ° C., preferably 50 to 150 ° C., and the pressure ranges from atmospheric pressure to 5 MPa.

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

[0025]

The present invention will be described below in detail with reference to examples. The feedstock used in Examples and Comparative Examples is a residual oil (hereinafter referred to as “raw material”) by-produced when producing purified naphthalene by acid extraction, distillation, and crystallization of coal tar oil, and its composition (% by weight). Was as follows.

Naphthalene 93.0% Benzothiophene 6.0% 1-methylnaphthalene 0.1% 2-methylnaphthalene 0.1% Quinoline 0.1% Others (dimethylindane, etc.) 0.7%

Example 1 Commercially available beta zeolite (silica / alumina ratio: 5)
0, molded product) and sieved (26 mesh-48 mesh)
h) was used for classification. The classified zeolite was exchanged with calcium ions using calcium chloride to prepare a calcium beta-type zeolite, which was calcined at 350 ° C. for 4 hours and cooled with a desiccator. 20 g of this adsorbent
Was packed in a steel cylindrical tube having an inner diameter of 8 mm and a length of 500 mm to form an adsorption column. Maintaining the column temperature at 50 ° C.
Cyclohexane was supplied to the column at a rate of 5 ml / min as a desorbing agent, and packed in the column.

Raw materials (1,3,5-
1.25m)
and then cyclohexane was supplied at a rate of 1 ml / min for 60 minutes. At this time, the effluent was collected every 30 seconds and analyzed by gas chromatography. The time was plotted on the horizontal axis and the analysis value was plotted on the vertical axis, and the point at which naphthalene and benzothiophene had the highest concentrations was measured as the retention time. Table 2 shows the results. The larger the retention time difference between naphthalene and benzothiophene, the easier the separation.

Example 2 Using calcium beta zeolite prepared in Example 1 and methylcyclohexane as a desorbing agent, the retention time was measured in the same manner as in Example 1. Table 2 shows the results.

Example 3 The retention time was measured in the same manner as in Example 1 using the calcium beta zeolite prepared in Example 1 and ethyl cyclohexane as the desorbing agent. Table 2 shows the results.

Example 4 The retention time was measured in the same manner as in Example 1 using the calcium beta zeolite prepared in Example 1 and isopropylcyclohexane as the desorbing agent. Table 2 shows the results.

Example 5 The calcium beta zeolite prepared in Example 1 was used, and 1,2-dimethylcyclohexane was used as a desorbing agent.
The retention time was measured in the same manner as in Example 1. Table 2 shows the results.

Example 6 Using calcium beta zeolite prepared in Example 1 and decalin as a desorbing agent, the retention time was measured in the same manner as in Example 1. Table 2 shows the results.

Example 7 The retention time was measured in the same manner as in Example 1 using the calcium beta-type zeolite prepared in Example 1 and bicyclohexyl as the desorbing agent. Table 2 shows the results.

Example 8 Using calcium beta zeolite prepared in Example 1 and hexane as a desorbing agent, the retention time was measured in the same manner as in Example 1. Table 2 shows the results.

Example 9 Using calcium beta zeolite prepared in Example 1 and heptane as a desorbing agent, the retention time was measured in the same manner as in Example 1. Table 2 shows the results.

Example 10 Using the calcium beta zeolite prepared in Example 1 and octane as the desorbing agent, the retention time was measured in the same manner as in Example 1. Table 2 shows the results.

Example 11 Using calcium beta zeolite prepared in Example 1 and isooctane as a desorbing agent, the retention time was measured in the same manner as in Example 1. Table 2 shows the results.

Example 12 Using the calcium beta zeolite prepared in Example 1 and toluene as the desorbing agent, the retention time was measured in the same manner as in Example 1. Table 2 shows the results.

Example 13 The retention time was measured in the same manner as in Example 1 using the calcium beta-type zeolite prepared in Example 1 and paraxylene as the desorbing agent. Table 2 shows the results.

Example 14 Using sodium beta zeolite prepared in the same manner as in Example 1, and using ethylcyclohexane as the desorbing agent, the retention time was measured in the same manner as in Example 1. Table 2 shows the results.

Example 15 Using potassium beta zeolite prepared in the same manner as in Example 1, ethyl cyclohexane as a desorbing agent,
The retention time was measured in the same manner as in Example 1. Table 2 shows the results. In each of the examples, the retention time of dimethylindane was clearly shifted between naphthalene and benzothiophene.

Comparative Example 1 Using a commercially available Na-substituted A-type zeolite and using ethylcyclohexane as a desorbing agent, the retention time was measured in the same manner as in Example 1. Table 3 shows the results. It can be seen that the retention times of naphthalene and benzothiophene were the same, indicating no separation.

Comparative Example 2 Using a commercially available Na-substituted A-type zeolite and using toluene as a desorbing agent, the retention time was measured in the same manner as in Comparative Example 1. Table 3 shows the results. It can be seen that the retention times of naphthalene and benzothiophene were the same, indicating no separation.

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

According to the separation and recovery method of the present invention, both components can be efficiently separated from a mixture containing naphthalene and benzothiophene by a simple adsorption method, so that naphthalene and / or benzothiophene can be recovered. Or it is useful as a purification method. In addition, components having similar boiling points, such as dimethylindane, can be separated at the same time.

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Claims (3)

[Claims] 1. Separation and recovery of benzothiophene and naphthalene from a mixture containing benzothiophene and naphthalene, wherein the two components are adsorbed and separated using a beta-type zeolite as an adsorbent when both components are adsorbed and separated. Method. 2. Ia group or IIa of the periodic table as an adsorbent
The method for separating and recovering benzothiophene and naphthalene according to claim 1, wherein the adsorption and separation are performed using a beta zeolite ion-exchanged with a metal belonging to the group III. 3. The method according to claim 1, wherein a desorbing agent is used in the adsorption separation, and an aliphatic hydrocarbon having 6 to 12 carbon atoms or an aromatic hydrocarbon having 6 to 10 carbon atoms is used as the desorbing agent. Or the method for separating and recovering benzothiophene and naphthalene according to 2.