JPH09216839A - Production of vinyl biphenyl - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain continuously stably, for a long period of time and inexpensively a vinyl biphenyl mixture in a liquid at a normal temperature by using an ethyl biphenyl mixture as a starting raw material and passing through a dehydrogenation reaction, etc. SOLUTION: A raw material oil containing ethyl biphenyl is brought into contact with a dehydrogenating catalyst to dehydrogenate in the presence of steam and the resultant product gas containing a vinyl biphenyl is quenched by adding with a cooling solvent, then the vinyl biphenyl is recovered as a solution or a dispersion of the solvent, thus subjected to a purifying process. Preferably, in the ethyl vinyl, a concentration of 3-ethyl biphenyl is <=65wt.% and a concentration of 4-ethyl biphenyl is <=15wt.%, and the solvent is benzene, etc., and the purifying process is decoloration by an activated carbon and/or a purification by distillation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing vinylbiphenyl useful as a resin modifier or a monomer for polymerization or copolymerization from a feedstock oil containing an ethylbiphenyl isomer mixture.

[0002]

As a method for producing vinyl biphenyl, a coupling reaction utilizing a complex of an alkyl halide and a metal (Burnagin NA et al., Metaloo).
rg. Khim. , 1989, 2 (4) 893-89.
7; Izv. Akad. NaukSSSR, Ser. K
him. , 1985, (9) 2120-2129). This method is suitable for small-scale production, but it is necessary to strictly control the mixing of water and other polar compounds in the feed oil, and further it is necessary to decompose the metal complex after the reaction. It is not suitable for large production.

In addition, a photolysis reaction is used (Takamaku
Setsuo et al., The Chemical Society of Japan, 1984 (1) 67-74).
Although it is also known, it uses light having a high level of energy and is not a method suitable for industrial mass production.

Further, as in the dehydrogenation reaction of ethylbenzene, a production method by a dehydrogenation reaction of ethylbiphenyl can be considered. However, if the technique for producing styrene by dehydrogenation of ethylbenzene is applied as it is, there is a problem that the vinyl biphenyl polymer is clogged inside the heat exchanger that condenses the gas produced by the dehydrogenation reaction and continuous operation cannot be performed.

As a means for solving this problem, Japanese Patent Laid-Open No. 4-2
No. 02145 discloses a production method for obtaining 4-vinylbiphenyls by adding a good solvent to a dehydrogenation reaction product, quenching the solution, concentrating the good solvent, and then adding a lower alcohol having a purity of 95% or more to crystallize the product. Is disclosed. The product obtained here is solid at room temperature. However, this method has complicated purification steps and requires crystallization equipment and solvent recovery equipment, so it cannot be said to be an industrial method.

A mixture containing 3-vinylbiphenyl as a main component is also an industrially useful substance, but the one obtained by the dehydrogenation reaction of 3-ethylbiphenyl has a poor color tone and affects the quality of the final product. , Can not be used industrially,
Its use was limited.

[0007]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent, during the production of a vinylbiphenyl mixture by a dehydrogenation reaction of an ethylbiphenyl mixture, a blockage due to the deposition or polymerization of a crystalline compound at the outlet of the dehydrogenation reactor. Another object of the present invention is to provide a method for industrially producing a vinylbiphenyl mixture that is liquid and is liquid at room temperature.

[0008]

[Means for Solving the Problems] That is, according to the present invention, a feed oil containing ethylbiphenyl is dehydrogenated by contacting it with a dehydrogenation catalyst in the presence of steam, and cooled to a reaction product gas containing vinylbiphenyl. Add solvent and quench,
In the method for producing vinylbiphenyl, vinylbiphenyl is recovered as a solution or dispersion of the cooling solvent and then subjected to a refining operation.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The ethylbiphenyl used as a raw material in the present invention may be a single compound or a mixture of several isomers. Further, ethylbiphenyl may contain some impurities. The feedstock oil may be ethyl biphenyl itself or may be one obtained by dissolving it in an aromatic hydrocarbon solvent having a substituent that does not undergo a dehydrogenation reaction such as toluene or an unsubstituted aromatic hydrocarbon solvent.

For the production of the vinylbiphenyl isomer mixture or 3-vinylbiphenyl, the concentration of 3-ethylbiphenyl in the raw material ethylbiphenyl is set to 65% by weight or more, or the concentration of 4-ethylbiphenyl is set to 15% by weight or less, preferably. It is preferable that the 3-ethylbiphenyl concentration is 75% by weight or more or the 4-ethylbiphenyl concentration is 10% by weight or less. When the concentration of 3-ethylbiphenyl in the starting material ethylbiphenyl is low or the concentration of 4-ethylbiphenyl is high, crystalline components are deposited at the outlet of the dehydrogenation reactor, and the polymerization inhibiting effect is weakened.

The dehydrogenation reaction is carried out by charging ethylbiphenyl and steam into a reactor filled with a dehydrogenation reaction catalyst. The reaction temperature varies depending on the type of catalyst, SV, feed oil composition, steam ratio, etc., but is preferably in the range of 580 to 680 ° C. The steam ratio (to ethyl biphenyl) is usually 1 to
20 times by weight, preferably 3 to 12 times by weight. The dehydrogenation reaction catalyst, a catalyst used in the dehydrogenation reaction of ethylbenzene, for example, iron-potassium-chromium-oxygen system,
Examples thereof include iron-chromium-vanadium-cobalt-potassium-oxygen-based iron oxide catalysts and the like.

The reaction product gas flowing out from the reactor is, in addition to vinylbiphenyl, reaction by-products such as methylbiphenyl and biphenyl, and high-boiling compounds such as unreacted ethylbiphenyl and low-boiling compounds or gases such as steam and hydrogen. It is mainly composed of minutes and has a temperature close to the above reaction temperature. This reaction product gas is cooled, and vinylbiphenyl is recovered by separating it into an oil phase and an aqueous phase.However, when it is cooled with an ordinary heat exchanger, the clogging inside the heat exchanger is severe, so continuous operation is not possible. Have difficulty. Also, when an oil containing 4-ethylbiphenyl in a ratio other than the above range is used when producing a vinylbiphenyl mixture, crystalline 4-vinylbiphenyl is deposited or polymerized inside the reactor. Therefore, blockage occurs inside the heat exchanger. Therefore, in the present invention, a cooling solvent is added to the reaction product gas flowing out from the reactor, preferably the reaction product gas immediately after flowing out, to quench it, and as described above, the ethylbiphenyl isomer ratio in the feed oil is adjusted. This solved the blockage problem.

The cooling solvent used in the present invention preferably has a high thermal stability and a large difference in boiling point and melting point with vinyl biphenyl, ethyl biphenyl and the like. It is a solvent with excellent cooling capacity and vinyl biphenyl dissolution capacity. In this case, the cooling capacity of the reaction product gas is more important than the dissolution capacity of vinylbiphenyl. Specific examples of the cooling solvent include benzene, alkylbenzene, alkylbiphenyl, polyalkylbenzene, polyalkylbiphenyl, and alkylated residual oil having a carbon number of 1 to 12 per side chain alkyl group having a melting point of 10 Examples thereof include aromatic hydrocarbons having a temperature of not more than 0 ° C., aliphatic hydrocarbons having a total carbon number of 5 to 12, and water. And as a cooling solvent, you may use 1 type among these, and may use 2 or more types together.

The amount of the cooling solvent used is at least an amount sufficient to cool the reaction product gas, and preferably 1 to 20 times the volume of the raw material ethylbiphenyl. Further, the liquid temperature of the cooling solvent is preferably kept at room temperature or lower temperature. Then, the cooling solvent is preferably sprayed uniformly to the heat exchanger in order to charge it for the purpose of preventing thermal polymerization of the crystal component in the apparatus.

The reaction product obtained here comprises an aqueous phase and an oil phase containing vinylbiphenyl and the like, and vinylbiphenyl can be recovered by gas-liquid separation and oil-water separation from this. Gas-liquid separation can be performed by a known method, and oil-water separation can be performed by specific gravity difference separation. The obtained oil phase, that is, the produced oil, contains vinylbiphenyl, ethylbiphenyl, etc. and the added cooling solvent as the main components. The recovered ethylbiphenyl can be reused as a raw material for dehydrogenation reaction.

Examples of the refining operation of the product oil containing vinylbiphenyl include decolorization treatment with activated carbon and distillation refining, and if necessary, both may be combined. Thus, according to the present invention, it is possible to produce vinylbiphenyl which is industrially advantageous at low cost. It should be noted that, in Japanese Patent Publication No. 4-202145, the boiling point of 4-vinylbiphenyl is so high that purification by distillation is difficult, but in the present invention, the ratio of 4-vinylbiphenyl is lowered to By using vinyl biphenyl as the main component, it became possible to purify by ordinary distillation.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the examples.

Examples 1 and 2 500 ml of iron oxide type catalyst (Nissan Gardler G-84D) was filled in a dehydrogenation reaction tube having an inner diameter of 40 mm and a length of 1 m, and 3-ethylbiphenyl (hereinafter referred to as a raw material oil A) was used as a raw material oil. Was sent to the vaporizer at 100 ml / hour for vaporization and charged into the reactor together with steam. The steam ratio (to 3-ethylbiphenyl) was 5 times by weight. 10 from reactor outlet
A cooling solvent spray nozzle was provided at a position of cm, and water as a cooling solvent was spray-added 10 times by volume to the reaction product gas flowing out from the reactor. This dehydrogenation reaction was continued for 60 hours,
Stable operation was possible without blockages in the piping. The produced oil obtained by gas-liquid separation and oil-water separation of the effluent was analyzed by gas chromatography. Then, after maintaining the liquid temperature of the produced oil at 20 ° C., 0.05 weight times of activated carbon was added to the produced oil, and the mixture was shaken at 20
It was shaken for a minute to be decolorized, and this was filtered off with a filter paper to obtain a purified oil. The produced oil and the refined oil are VR manufactured by JASCO Corporation.
Absorbance was measured using -510. Table 1 shows the reaction temperature and the experimental results, and Table 2 shows the analysis results of the feed oil A and the produced oil.
Table 3 shows the absorbances of the produced oil and the refined oil.

Examples 3 and 4 As the feedstock, the isomer ratio (3-ethylbiphenyl / 4-
An experiment was conducted in the same manner as in Examples 1 and 2 except that an ethylbiphenyl mixture having an ethylbiphenyl of 8 (hereinafter, referred to as raw oil B) was used. The reaction conditions and results are shown in Table 1,
Table 2 shows the analysis results of the raw oil B and the produced oil, and Table 3 shows the absorbances of the produced oil and the refined oil.

Comparative Example 1 Except that water as a cooling solvent was not sprayed onto the dehydrogenation reaction product gas,
An experiment was conducted in the same manner as in Example 2 using the raw material oil A. When this experiment was continued for 2 hours, the operation inside had to be stopped because of blockages in the piping. The reaction temperature and the experimental results are listed in Table 1.

Comparative Example 2 Except that water as a cooling solvent was not sprayed on the dehydrogenation reaction product gas,
An experiment was conducted in the same manner as in Example 4 using the stock oil B. When this experiment was continued for 2 hours, the operation inside had to be stopped because of blockages in the piping. The reaction temperature and the experimental results are listed in Table 1.

[0022]

[Table 1]

In Table 1, the selectivities represent the selectivities of 3-vinylbiphenyl and 4-vinylbiphenyl.

[0024]

[Table 2]

In Table 2, BP is biphenyl, 3-M
BP is 3-methylbiphenyl, 4-MBP is 4-methylbiphenyl, 3-EBP is 3-ethylbiphenyl, 4-
EBP is 4-ethylbiphenyl, 3-VBP is 3-vinylbiphenyl, 4-VBP is 4-vinylbiphenyl, N
D represents non-detection, and the numerical value is% by weight.

[0026]

[Table 3]

[0027]

According to the production method of the present invention, an ethylbiphenyl mixture is used as a starting material, and a dehydrogenation reaction method and a simple decolorization treatment or distillation operation are carried out to continuously produce a vinylbiphenyl mixture which is liquid at room temperature. Can be stably manufactured at low cost for a long period of time. In addition, by adjusting the mixing ratio of the ethylbiphenyl isomers, the problem of clogging of the reactor due to the deposition and polymerization of crystalline compounds was solved, and continuous operation for a long period of time became possible. It is extremely useful as a manufacturing method.

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Claims (5)

[Claims] 1. A feedstock containing ethylbiphenyl,
Dehydrogenation by contacting with a dehydrogenation catalyst in the presence of steam,
A method for producing vinylbiphenyl, which comprises adding a cooling solvent to a reaction product gas containing vinylbiphenyl, quenching the solution, recovering vinylbiphenyl as a solution or dispersion of the cooling solvent, and then subjecting it to a refining operation. 2. The method for producing vinylbiphenyl according to claim 1, wherein the concentration of 3-ethylbiphenyl in ethylbiphenyl is 65% by weight or more. 3. The method for producing vinylbiphenyl according to claim 1, wherein the concentration of 4-ethylbiphenyl in ethylbiphenyl is 15% by weight or less. 4. The melting point of benzene, alkylbenzene, alkylbiphenyl, polyalkylbenzene, polyalkylbiphenyl, alkylated residual oil, etc. having a carbon number of 1 to 12 per side chain alkyl group as the cooling solvent is 10
The method for producing vinyl biphenyl according to claim 1, wherein the solvent is at least one solvent selected from the group consisting of aromatic hydrocarbons having a temperature of not higher than ° C, aliphatic hydrocarbons having a total carbon number of 5 to 12, and water. 5. The method for producing vinylbiphenyl according to claim 1, wherein the refining operation is decolorization with activated carbon and / or purification with distillation.