JPS5988432A - Method for separating methylnaphthalene - Google Patents

Abstract

PURPOSE:To separate 2-methylnaphthalene efficiently from a mixture of organic compounds containing 1-methylnaphthalene and the 2-methylnaphthalene, by adsorbing and separating the 2-methylnaphthalene chromatographically using zeolite having a specific open pore diameter. CONSTITUTION:A fraction of organic compounds consisting substantially of carbon, hydrogen, oxygen and nitrogen, and containing 1-methylnaphthalene and 2- methylnaphthalene, preferably a coal tar fraction or the faction treated with a caustic alkali, washed with an acid or treated with an adsorbent, etc. is brought into contact with zeolite having about >=6Angstrom open pore diameter, preferably zeolite Y containing copper in most of the substituted cation, and the adsorbed compounds are developed with a developing agent to separate advantageously the 2-methylnaphthalene useful as a raw material for vitamin K from the above- mentioned mixture. In case the zeolite is the above-mentioned zeolite Y, tetralin or anisole is preferred for the developing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for separating and obtaining 2-methylnaphthalene from a mixture of organic compounds containing 1-methylnaphthalene and 2-methylnaphthalene. More specifically, it relates to a method of chromatographic adsorption separation using zeolite.

Methylnaphthalene is useful as a solvent, a dye carrier, and a raw material for various organic synthesis, even in the form of mixtures, but among these, 2-methylnaphthalene is a raw material for vitamins, and its added value is high, so demand has increased in recent years. Since the amount of 2-methylnaphthalene is increasing, it would be of great significance if 2-methylnaphthalene could be separated industrially.

2-Methylnaphthalene is usually contained in crude methylnaphthalene obtained by fractional distillation of coal tar. However, this crude methylnaphthalene also contains 1-methylnaphthalene, biphenyl, acenaphthene, diphenylene oxide, indole, dimethylnaphthalene, and the like. Among these, 1
- Methylnaphthalene has a boiling point of 244.8°C, which is close to the boiling point of 2-methylnaphthalene, 241.4°C, and it is difficult to separate it by distillation, so if you want to obtain highly pure 2-methylnaphthalene, l -Separation from methylnaphthalene is the biggest problem. Also, 2-methylnaphthalene and 1-
Since methylnaphthalene forms a eutectic mixture with 17.5% by weight of 2-methylnaphthalene, it is difficult to separate it by cooling crystallization.

J, Soc, Chem, Ind, , 53, 7
31f1934), the methylnaphthalene fraction (236-240°C) of coal tar was treated with picric acid, and the resulting methylnaphthalene mixture was sulfonated by decomposition of vicrate, and then 2 - It is described that 1-methylnaphthalene was obtained by separating methylnaphthalene derivatives and insoluble 1-methylnaphthalene based on the difference in solubility and steam decomposition in 70% sulfuric acid kept at 150°C. This method has many process steps and is not an efficient method.

As described above, in the conventional techniques, separation of 2-methylnaphthalene and 1-methylnaphthalene is extremely troublesome, and an efficient separation method is not yet known.

The present inventors changed their thinking in order to overcome the drawbacks and problems of conventional methods, and as a result of intensive research into the feasibility of a molecular sieve separation method that had never been proposed before, they found that: - When separating and obtaining 2-methylnaphthalene from a mixture of organic compounds consisting essentially of carbon, hydrogen, oxygen and/or nitrogen, including methylnaphthalene and 2-methylnaphthalene, the above mixture is added to a zeolite with an opening diameter of about 6 Å or more. It has been discovered that 2-methylnaphthalene can be efficiently separated by contacting with 2-methylnaphthalene and developing it chromatographically with a developing agent, leading to the present invention.

That is, when the above mixture or a solution of the above mixture dissolved in an appropriate solvent is brought into contact with a zeolite having an opening diameter of about 6 Å or more, each component in the mixture is adsorbed by the zeolide, but 1-methylnaphthalene and 2-methyl Because naphthalene and naphthalene have different adsorption properties, they are each developed and separated as they are repeatedly adsorbed and desorbed by the developing agent in the developing column.

The purpose is achieved by collecting the separated parts.

Many types of zeolites are known, including naturally occurring ones and artificially synthesized ones. However, these zeola,
Not all of them are effective as adsorbents for separating 2-methylnaphthalene according to the present invention, but those having an opening diameter larger than the molecular size of methylnaphthalene, that is, about 6 or more are effective. .

Zeolites with an opening diameter of 6 Å or more include the ZSM group represented by X type, Y type, L type 4, omega type, faujasite, mordenite, and ZSM-5.

Among these, when evaluated from an industrial standpoint, the most preferred adsorbents are X-type zeolite and Y-type zeolite, which are produced on an industrial scale.

X-type zeolite is expressed as an oxide: Na2O・Al2O
3.2.55i02.6H20, unit cell constant display:
Na36C (AI OJg6(Sin),.6]・2
64 H2O, density: 1.93v hawk, unit cell constant: 25.02-24.86 large, void volume: 0.5
0CC/ω, open diameter = 12-membered ring - 7.4 people, 6-membered ring - 2
, 2A, is a zeolite characterized by velocity aperture diameter: 8.1.

Y-type zeolite has an oxide display: Na2O・A1□0
3・4.8SiO2・8.9H20, unit cell constant display: Na56 ((A102)56 (Sf02)136
) ・250-H2O, density: 1.92 t/cc1 unit cell constant: 24.85-24.61 i, void volume = 0.48 CC/CC, open diameter: 12-membered ring-7,4
Person, 6-membered ring - 2, 2 large, speed opening diameter: 8. It is a zeolite characterized by lA.

Therefore, the X-type zeolite and Y-type zeolite used in the present invention may be any composition having the crystal structure as described above, and any X-type zeolite synthesized by a conventionally known method may be used.
Type zeolite and Y type zeolite can also be used.

1. In the above description of X-type zeolite and Y-type zeolite, Na is used mainly due to threat requirements during the synthesis of zeolite, and in order to achieve the purpose of the present invention, Na is used in X-type zeolite and Y-type zeolite. It is necessary to substitute some or all of the cations constituting the zeolide with a specific metal ion to exhibit a high degree of selective separation.

By changing the type of metal ion, the opening diameter changes,
In addition, the interaction between the metal ion and the substance to be separated changes, and the selective separation properties change due to both effects.

The separation coefficient described below is used as a measure of selective separability. The separation coefficient is the value of component A when a liquid containing two specific components A and B is brought into contact with an adsorbent and an equilibrium state is reached.
, B are the values of B defined by the above formula, where XA and XB are the concentrations of the liquid phase, respectively, and YA and YB are the concentrations of the adsorbed phase, respectively.

As an example, commercially available A, Add Zeolite) 0.52 to .07 and heat to 70°C.
After contacting for 4 hours, the separation coefficient was determined. The results are shown in Table 1, which explains which metal ions are preferred.

In Table 1, the adsorption capacity W is also listed together with the separation coefficient.

The adsorption capacity is defined by the following formula, and the larger this value is, the higher the actual separation efficiency is, so it is preferable.

As for the performance of the adsorbent, it is preferable that the separation coefficient between 1-methylnaphthalene and 2-methylnaphthalene be high, and the adsorption capacity must also be at a certain level or higher (approximately 1507 nf/li' zeolite).

Looking at Table 1 from the above perspective, we can see that Y-type zeolite ion-exchanged with potassium, barium, silver or copper;
X-type zeolite ion-exchanged with silver or potassium is preferred. Preferably, these substituted cations replace at least 60% of the exchange capacity of the zeolite. A-type zeolite, which has a small opening diameter of about 4, has a small adsorption capacity and is not suitable for use.

Cation exchange can be carried out using water-soluble salts of the ions to be exchanged, such as hydrochlorides, nitrates, sulfates, carbonates, etc., or compounds that generate the ions to be exchanged, such as metals, oxides, hydroxides, etc. This is carried out by bringing zeolite into contact with a solution dissolved in hydrochloric acid, nitric acid, sulfuric acid, etc. The amount of cations used is preferably 0.8@ or more of the equivalent of exchangeable cations in the zeolite. The ion concentration of the solution in the trench ion exchange reservoir is selected to be an appropriate concentration below the saturation concentration, and is usually between 0.01 and 4 normal and below the saturation concentration. When performing ion exchange with mixed metal ions, a solution of a common anion is utilized.

The shapes of the X-type zeolite and Y-type zeolite used in the present invention are appropriately selected depending on the method of contacting the mixture to be separated and the zeolite. It may be in powder form or crushed form,
It may be a molded product obtained by single-sided compression molding, extrusion molding, molding with a marmerizer, molding with a spray ryer, or the like.

Next, the developing agent must be selected appropriately, taking into account the substituted metal ions of the zeolite used.

In fact, when chromatographically separating 1-methylnaphthalene and 2-methylnaphthalene, chromatographic separation is only possible if zeolite substituted with the above-mentioned preferred metal ions and a specific developing agent corresponding thereto are available. In the present invention, when the zeolite is Y-type and the cation is copper, the suitable developer is tetralin or anisole.

To separate methylnaphthalene using the adsorbent and developing agent of the present invention, commonly used adsorption separation operations, ie, batch chromatographic separation method and continuous chromatographic separation method, are applied. The batch chromatographic separation method herein refers to the following operations.

1. A developing column filled with adsorbent to the required length is first filled with the developing agent, and from one end of the column, a mixture containing 1-methylnaphthalene and 2-methylnaphthalene or this mixture is poured into a suitable solvent. A predetermined amount of the solution dissolved in the . Next, a predetermined amount of developing agent is introduced from the rear of the mixture, the developing agent moving from the rear detaches the adsorption zone, and each component is moved forward while being expanded. Each component in the mixture begins to separate in the developing column depending on the difference in adsorption power. When the separation of 1-methylnaphthalene and 2-methylnaphthalene has sufficiently progressed, the portion rich in 2-methylnaphthalene is extracted. Also 2
- It is also possible to measure the increase in the concentration of 2-methylnaphthalene recovered by feeding a portion of the part where methylnaphthalene is not completely separated from other components before and after feeding the mixture.

Continuous chromatographic separation is a method in which the mixture inlet is moved to an appropriate position in the adsorption zone according to the advancing speed of the adsorption zone separated into each component as it progresses in the developing column. l-methylnaphthalene and 2 from the respective positions.
- A steady state is achieved by withdrawing the methylnaphthalene-rich liquid and replenishing the insufficient developing agent from an appropriate location outside the staghorn zone, which continuously produces 1-methylnaphthalene and 2-methylnaphthalene.
This is a method to separate methylnaphthalene.

In both batch and continuous processes, the product is usually obtained in a state dissolved in a developer, but the developer of the present invention and methylnaphthalene have considerably different boiling points and can be separated by year-round distillation.

The temperature at which the mixture and the developer are brought into contact with the zeolite must be at least the temperature at which the mixture coagulates and licks, and specifically preferably at room temperature or higher. The upper limit of temperature varies depending on the boiling point of the developing agent used. In the case of the present invention,
The boiling point of tetralin is 207℃, and the boiling point of anisole is 15℃.
The temperature is 4℃, and it can be used up to quite high temperatures, but it can be used up to 190℃.
The above is economically unfavorable because the energy required for heating becomes too large. Therefore, it is preferable to operate at a temperature of room temperature or higher and lower than 190°C.

The mixture to be separated which can be applied to the present invention may be any mixture of organic compounds consisting essentially of carbon, hydrogen, oxygen and/or nitrogen, including 1, 2-methylnaphthalene and 2-methylnaphthalene.

A suitable example is coal tar fraction. In addition, for the purpose of refining this coal tar fraction, caustic alkali treatment,
It can also be applied to fractions that have been subjected to acid washing, distillation, adsorbent treatment, etc.

According to the present invention, l-
It becomes possible to separate methylnaphthalene and 2-methylnaphthalene, and its industrial significance is significant.

Examples of the present invention and comparative examples outside the present invention are shown below, but the present invention is not limited to these Examples.

Example 1 A commercially available Y-type zeolite powder was granulated by spray drying to form spheres with a particle size of approximately 200 to 300 μm, which were then treated with an approximately 2N chloride aqueous solution at 70° C. for 4 hours. Perform this operation 3
After repeated washing, it was washed with water and dried at 90°C for 6 hours. Next, the zeolite treated as described above was calcined at 400° C. for 4 hours and cooled in a desiccator. This is 2.2m in diameter
, and packed into a 3 m long cylindrical stainless steel column.

The temperature of the crumb was maintained at 150°C, and from one end of the column,
Anisole as a developing agent at a superficial flow rate of 5 m/br
When anisole begins to flow out from the other end, switch the supply cock and add 10μ of the liquid to be separated with the following composition.
1 was fed at the same flow rate.

Next, anisole as a developing agent was fed again at the same rate until the substance to be separated was eluted from the column.

Effluent was collected at regular intervals and subjected to analysis. The relationship between the outflow (elution) time and the concentration of each component is shown in Figure 1, and it can be seen that 1-methylnaphthalene and 2-methylnaphthalene are separated.

Example 2 Tetralin was used as a developing agent, and the column temperature was set to 180℃.
1-Methylnaphthalene and 2-methylnaphthalene were separated in the same manner as in Example 1 except that the temperature was maintained at .degree.

FIG. 2 shows the relationship between the outflow (on the bath) time and the temperature of each component. In this case as well, 1-methylnaphthalene and 2-methylnaphthalene are separated.

Comparative Example 1 A commercially available Y-type zeolite powder was granulated by spray drying to form spheres with a particle size of approximately 200 to 300 μm, which were then treated with an approximately 2N aqueous potassium chloride solution at 70° C. for 4 hours. This operation was repeated three times, followed by washing with water and drying at 90° C. for 6 hours. Next, the above-treated zeolite was heated at 400°C (4:1-1) and calcined, and cooled in a desiccator. Ethylbenzene as a developing agent was supplied from one end at a superficial flow rate of 5 f?'L/hT, and when ethylbenzene began to flow out from the other end, the supply cock was switched, and 10 μl of the liquid to be separated with the following composition was added at the same flow rate. supplied.

Next, ethylpenzene as a developing agent was fed again at the same rate as U, and this was continued until the substance to be separated was eluted from the column.

Effluent was collected at regular intervals and subjected to analysis. The relationship between the outflow (elution) time and the concentration of each component is shown in Figure 3, which shows that the components are not separated.

[Brief explanation of the drawing]

FIG. 1 illustrates the relationship between time and the concentration of each component in the effluent from the column in Example 1. FIG. 2 illustrates the relationship between time and the concentration of each component in the effluent from the column in Example 2. FIG. 3 illustrates the relationship between ll:j4 and the daughterness of each component for the effluent from the column in Comparative Example 1. Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] 1. When separating and obtaining 2-methylnaphthalene from a mixture of organic compounds consisting essentially of carbon, hydrogen, oxygen and/or nitrogen containing 1-methylnaphthalene and 2-methylnaphthalene, the opening diameter is about 6λ or more. A method for separating methylnaphthalene characterized by contacting the above mixture with zeolite and separating it by developing it chromatographically with a developing agent 11-Methylnaphthalene and 2-methylnaphthalene containing substantially carbon, hydrogen, oxygen and/or A method for separating methylnaphthalene according to claim 1, characterized in that the mixture of organic compounds consisting of nitrogen is a coal tar fraction. Claim 1, characterized in that the mixture of organic compounds consisting of , oxygen and/or nitrogen is a fraction obtained by subjecting a coal tar fraction to caustic alkali treatment, acid washing, distillation, adsorbent treatment, etc. Method for separating methylnaphthalonone as described in Claim 4-- The zeolite having an opening diameter of about 6 Å or more is a Y-type zeolide, and most of the substituent cations are I copper, Method 5 for separating methylnaphthalene according to any one of Items 2 and 3, 75iY-type zeolite (zeolite with an aperture diameter of about 6λ or more), in which most of the substituted cations are I copper, and the developing agent is The method for separating methylnaphthalene according to any one of claims 1, 2 and 3, characterized in that it is tetralin or anisole.