JPH08183750A - Production of m-ethylphenol - Google Patents

Abstract

PURPOSE: To efficiently produce m-ethylphenol under the suppression of the formation of impurities by reacting o- or p-ethylphenol in the presence of a solid acid catalyst and phenol. CONSTITUTION: A process for converting o- or p-ethylphenol to m-ethylphenol in the presence of a solid acid catalyst (e.g. silica-alumina catalyst) is carried out under the coexistence of phenol. Phenol is added in a molar ratio of 0.2-5 based on the total amount of the monoethylphenols. The conversion is carried out at 330-430 deg.C through an isomerization reaction or a transalkylation reaction. Further, when a continuous system is applied to the process, the formation of the byproducts of diethylphenols is more effectively suppressed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for efficiently producing m-ethylphenol from o- or p-ethylphenol.

[0002]

2. Description of the Prior Art m-Ethylphenol was obtained in a relatively high yield by the sulfonated alkali-melting method of ethylbenzene and is currently produced exclusively by this method. However, since a large amount of harmful wastewater is produced as a by-product, a method using ethylation of phenol instead of this is being studied. In this way, a mixture of o-, m-, p-ethylphenol is obtained, which is separated by distillation and then
M-Ethylphenol is separated and collected by adsorption separation or the like. In order to increase the yield of m-ethylphenol, it is reported that the recovered p-ethylphenol can be contacted with a solid acid catalyst or the like to isomerize to m-ethylphenol (US2551628 and the like).

[0003]

However, in the case of this method, m-ethylphenol is produced, and phenol and diethylphenol are by-produced by the concurrent disproportionation reaction, resulting in a decrease in m-ethylphenol yield. Further, depending on the type of diethylphenols produced as a by-product, they cannot be easily separated by distillation, which is one of the factors that hinder high purification.

The present invention comprises o-ethylphenol and p
-Production of m-ethylphenol capable of suppressing the by-product of undesired impurities such as diethylphenol when isomerizing ethylphenol to produce m-ethylphenol and improving the yield of m-ethylphenol It is intended to provide a way.

[0005]

The present invention has been made to solve the above-mentioned problems, and when o- or p-ethylphenol is converted to m-ethylphenol in the presence of a solid acid catalyst, The object is achieved by a method for producing m-ethylphenol, which is characterized by coexisting with phenol. By applying this production to a continuous reaction, the objective could be achieved to a higher degree.

The raw material for converting to m-ethylphenol is o
-Ethylphenol or p-ethylphenol may be used as long as it contains one or both of them, but usually o
It is a mixture of two or three ethylphenol isomers among the-, p-, and m-forms, and may further contain diethylphenol. A particularly suitable starting material for the process of the invention is the residue obtained by separating these desired ethylphenols from the ethylphenol isomer mixture formed during the production of m-ethylphenol or p-ethylphenol by ethylation of phenol. By-products can be mentioned. Since the o-form of the three isomers can be separated by distillation, the main object is a mixture having the m-form and the p-form as products.

The present invention is characterized in that such a raw material contains phenol. The content of phenol is 0.2 to 5, preferably 0.5 to 2, in molar ratio with respect to the whole monoethylphenol. In addition to newly adding phenol, the phenol is ethylated to m- or o-
You may operate by adjusting reaction conditions at the time of manufacturing ethylphenol, so that a predetermined amount of phenol may remain in a by-product.

Furthermore, when this production method is applied to a continuous reaction, the production of by-products can be reduced to a higher degree.

Examples of the solid acid catalyst include silica-alumina, zeolite, tungstosilicic acid, solid phosphoric acid and γ-alumina. This catalyst may be any one that can convert o-ethylphenol or p-ethylphenol into m-ethylphenol, and this conversion may be based on a transalkylation reaction in addition to an isomerization reaction.

The reaction temperature is suitably 330 to 430 ° C, preferably 370 to 430 ° C. Reaction temperature is 330 ℃
Below, a sufficient yield of m-ethylphenol cannot be obtained,
Further, if the temperature is higher than 430 ° C., by-product gas is generated, which is not preferable. The reaction pressure is atmospheric pressure, and the gas phase reaction takes place considering the boiling point.

As the reactor, an ordinary reactor for carrying out a catalytic reaction may be used.

Since the product is usually a mixture of o-, m-, p-form and phenol, the m-form is separated therefrom. First, of the components contained in the product, the phenol and the o-form can be separated from the m-form by distillation. Therefore, if they are removed by distillation prior to the above-mentioned adsorption separation, the load of the adsorption separation step can be reduced. Next, the method for separating the m- and p-forms is not particularly limited, but the adsorption separation method is preferred. Zeolite-based adsorbents are preferred for adsorption separation. The zeolite may be either synthetic zeolite or natural zeolite. A preferred zeolite is a crystalline aluminosilicate of Y-type zeolite having potassium or barium as a cation at an exchangeable cation position. Alcohol or the like can be used as the desorbent. Preferred alcohols are those of C ₃ -C _6. The peak is detected by GC or the like. Since the m-form comes out first due to desorption, it is separated and the alcohol is removed by distillation or the like, and is sent as it is or after further purification to the commercialization process. Since the p-form comes out later, the alcohol is removed by distillation or the like and circulated to the raw material.

The above separation method is used as a pre-stage of the method of the present invention, and the product is used as it is or with phenol and o-.
If the residue obtained by separating the body by distillation is circulated to the raw material of the method of the present invention, the whole method can be further efficiently carried out.

[0014]

When a mixture of ethylphenol isomers containing a large amount of p-ethylphenol after separating m-ethylphenol is catalytically reacted with a solid acid catalyst, isomerization of ethylphenol isomers and transalkylation of the isomers are performed. Reactions such as liquefaction and disproportionation occur, phenol and m-ethylphenol are produced, and further diethylphenol is by-produced. In the present invention, by-product of diethylphenol is suppressed by adding phenol to this step, and m-
It has been found that it promotes the production of ethylphenol.

Up to now, there has been a method of producing p-cresol by bringing phenol into the coexistence upon transalkylation and isomerization of a mixture of p-cresol isomers with a solid acid catalyst. (JP-A-2-83344) However, this method is obviously different in that it is an intramolecular or intermolecular transfer reaction of a methyl group, and the isomerization of ethylphenol of the present invention is a transfer reaction of an ethyl group.

[0016]

【Example】

Example 1 Using 20 g of p-ethylphenol and 10 g of phenol (molar ratio 1: 0.8) as raw materials, 1.0 g of silica alumina was filled in a 100 cc stainless autoclave, and a reaction was carried out at a reaction temperature of 350 ° C. for 1 hr. Table 1 shows the results. As can be seen from this example, in a system in which phenol coexists, by-products such as diethylphenols are less than in Comparative Example 1 below.

[0017]

[Table 1]

Comparative Example 1 The results of a reaction experiment conducted in the same manner as in Example 1 except that 30 g of p-ethylphenol was used as a raw material are shown in Table 2.
Shown in As can be seen from this example, if phenol is not added, a large amount of by-products such as diethylphenol are produced.

[0019]

[Table 2]

Example 2 As Example 1, except that phenol was added as a raw material to a mixture of p-ethylphenol and m-ethylphenol and the reaction was carried out under the conditions of a liquid hourly space velocity of 1.0 hr ^-1 , which is a continuous reaction. Table 3 shows the results of similar reaction experiments. As can be seen from this example, phenol is present in the same amount in a weight ratio with respect to the total amount of ethylphenol, and in a continuous system, there are less by-products such as diethylphenol than in Example 1, and phenol is removed. The yield of m-ethylphenol is also high.

[0021]

[Table 3]

Example 3 Table 4 shows the results of a reaction experiment carried out in the same manner as in Example 2 except that phenol was added to p-ethylphenol at a molar ratio of 1: 1.6 as a raw material. As can be seen from this example, the system in which phenol coexists has less by-products such as diethylphenols and the m-ethylphenol yield excluding phenol is higher than in Comparative Example 1.

[0023]

[Table 4]

Comparative Example 2 In order to investigate the reaction product in transalkylation and isomerization when a mixture of p-ethylphenol and m-ethylphenol was used as a raw material, a silica-alumina catalyst was used, and the reaction temperature was 400 ° C. The reaction treatment was performed under the conditions of a space velocity of 1.0 hr ⁻¹ . The results are shown in Table 5.

[0025]

[Table 5]

Reference Example 1 Table 6 shows the results of an experiment conducted at a reaction temperature of 300 ° C. in the same manner as in Example 3 except that phenol was added to p-ethylphenol as a raw material. When the reaction temperature is lowered, the yield of m-ethylphenol is lower than that in Example 3.

[0027]

[Table 6]

Comparative Example 3 p-Ethylphenol was used as a raw material, and a silica-alumina catalyst was used in the same manner as in Example 2 except that phenol was not added. The reaction temperature was 400 ° C. and the liquid hourly space velocity was 1.0 hr ⁻¹ . Table 7 shows the results of the reaction treatment performed in Step 1. The yield of m-ethylphenol is low.

[0029]

[Table 7]

Next, an example of a preferable apparatus used for the method of the present invention will be described with reference to the drawings. The ethylphenol isomer mixture as a raw material is supplied to the adsorption separation device 1 through a line 7. At this time, the adsorption separation device 1 has a fourth
A mixture of m, p-ethylphenol isomers, which is separated as a top from the distillation column 6 and is circulated through a line 19, is supplied. In the adsorption / separation device 1, for example, adsorption separation of an ethylphenol isomer mixture using a zeolite-based adsorbent as an adsorbent and an alcohol as a desorbent is performed, and a raffinate composed of m-ethylphenol and alcohol is provided in line 8.
Through the first distillation column 3 to collect alcohol as a product from the top of the column through a line 9 and from the bottom of the column through a line 10 as m-ethylphenol.

On the other hand, the extract containing a large amount of p-ethylphenol is sent to the second distillation column 2 through the line 11, and the alcohol is passed from the top of the column through the line 12 and the m, p-ethylphenol mixture is passed from the bottom of the line through the line 13. After being obtained, it is mixed with phenol through line 14 and sent to the isomerization reactor 4.

Ethylphenol after isomerization is obtained by line 17
Phenol and o-ethylphenol obtained from the top of the column and sent to the third distillation column 5 are circulated to the isomerization reactor 4 through a line 15. M, p-Ethylphenol and diethylphenols are obtained from the bottom of the column and line 1
It is sent to the fourth distillation column 6 via 8.

In the fourth distillation column 6, m, p-ethylphenol and diethylphenol are separated, and m, p-ethylphenol is separated as a column top fraction and circulated to the adsorption / separation unit 1 through a line 19. Diethylphenol is recycled to the isomerization reactor 4 via line 16 as a bottoms fraction.

[0034]

Industrial Applicability As described above, according to the present invention, by adding phenol, m-ethylphenol can be synthesized from an ethylphenol isomer mixture as a raw material with less by-products, and a continuous reaction is applied. As a result, the treatment can be performed at a higher level, which is a very advantageous industrial production method as compared with conventional methods.

[Brief description of drawings]

FIG. 1 is a flow sheet showing the configuration of an example of an apparatus to which the method of the present invention is applied.

Claims (3)

[Claims] 1. When converting o- or p-ethylphenol to m-ethylphenol in the presence of a solid acid catalyst,
Method for producing m-ethylphenol, characterized by allowing phenol to coexist 2. The method for producing m-ethylphenol according to claim 1, which is carried out by a continuous reaction. 3. The method for producing m-ethylphenol according to claim 1, wherein the amount of phenol is 0.5 to 2 in a molar ratio with respect to the total amount of monoethylphenol.