JP2002275111A - Method for producing cresol and xylenol each methylated at m- or p-position - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably produce cresol and xylenol each methylated at the m- or p-position for a long period without deteriorating the activity of a catalyst. SOLUTION: This method for producing the cresol and the xylenol each methylated at the m- or p-position comprises (1) methylating (transalkylating) a phenol compound of raw material such as phenol or o-cresol with a methylating agent selected from anisol, cresol, xylenol, trimethylphenol or methanol, (2) isomerizing a phenol compound selected from anisol, cresol, xylenol and trimethylphenol, or (3) methylating and isomerizing (transalkylating) the above- described phenol compound of raw material with at least two kinds of compounds selected from methylating agents and phenol compounds, wherein the reactions and isomerizations are carried out by bringing them into contact with a solid catalyst at reaction temperature of 350 to 700 deg.C at a reaction pressure of >=5 MPa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing cresol and xylenol in which the m-position or the p-position is methylated.

[0002]

2. Description of the Related Art Cresol and xylenol in which the m-position or the p-position is methylated are used as materials for flame retardants and solvents for electric wire varnishes. For these uses, those containing only a small amount of methylated only at the o-position, such as o-cresol and 2,6-xylenol, are preferred. Specifically, those used as a solvent for electric wire varnish or a raw material of a flame retardant include m-cresol, p-cresol, 2,4-xylenol, 2,5-xylenol, 3,5-xylenol, 2,3-xylenol Or a mixture thereof, and the content of these compounds is 70% by weight or more, preferably 90% by weight or more. These cresols and xylenol have a boiling point of 19
It is contained in a coal tar fraction at 0 to 220 ° C., and JP-A-60-248638 discloses a method in which cresol and xylenol are extracted from the coal tar fraction with an aqueous sodium hydroxide solution, neutralized with sulfuric acid or the like, and then further purified by distillation. Has been introduced. Further, JP-A-1-202990 describes a method for separating cresol methylated at the m-position and the p-position from a coal tar fraction.
No. 739 describes a method for separating xylenol methylated at the m-position from a coal tar fraction. Methods for separating these coal tar fractions include extraction, distillation,
In addition to the necessity of many steps such as neutralization, there is a drawback that the production amount is limited by the amount of coal tar generated.

Also, Applied Catalysis, 64 83-99 (199
0) is phenol and methanol at 200 to 500 ° C,
A method for synthesizing cresol and xylenol by contacting a solid acid catalyst in the gas phase under normal pressure is described. In this document, the higher the reaction temperature is, the higher the proportion of cresol methylated at the m- and p-positions is, but the higher the temperature is, the more remarkable the accumulation of carbides on the catalyst surface is, and the shorter the catalyst life is. This is not a practical synthesis method. JP-A-5-32574 discloses that cresol isomers are contacted with a solid acid catalyst to undergo isomerization transalkylation,
Although a method of obtaining m-cresol by precision distillation and adsorptive separation thereof is described, this method also has a possibility that the catalytic activity is reduced in a relatively short time. Therefore, in order to economically obtain cresol and cresol in which the m-position or the p-position is methylated by a synthesis method, it is necessary to select reaction conditions under which the catalyst life does not decrease even at a high temperature.

[0004]

DISCLOSURE OF THE INVENTION The present invention is directed to an m-position or a p-position.
It is an object of the present invention to economically produce cresol and xylenol having a methylated position under reaction conditions in which the catalytic activity does not decrease with time.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies on reaction conditions under which the catalyst life does not decrease even at a high temperature, and as a result, phenol, anisole, cresol, It has been found that the object can be achieved by bringing a reaction raw material such as xylenol, trimethylphenol, or methanol into contact with a solid catalyst at a higher density than the gas phase. That is, the present invention is a phenol, anisole, cresol, xylenol,
Trimethylphenol, a mixture of two or more of methanol or anisole, cresol, xylenol, trimethylphenol at 350 to 700 ° C and 5MPa
A method for producing cresol and xylenol in which the m-position or the p-position is methylated, wherein the cresol and the xylenol are methylated at the m-position or the p-position.

According to the present invention, there is provided at least one raw material phenol selected from phenol, cresols having a hydrogen which can be substituted at the m-position or p-position, and anisole;
At least one methylating agent selected from anisole, cresol, xylenol, trimethylphenol and methanol (however, the raw material phenol and the methylating agent are not the same) are solidified at 350 to 700 ° C and 5 MPa or more. A method for producing cresol or xylenol in which the m-position or the p-position is methylated, which is characterized by contacting with a catalyst. In addition, the present invention relates to a method for preparing at least one phenol selected from anisole, cresol, xylenol and trimethylphenol by 350 to 70.
A method for producing cresol or xylenol in which the m-position or the p-position is methylated, wherein the method is contacted with a solid catalyst at 0 ° C. and 5 MPa or more. Further, the present invention provides
The raw material phenols and at least two kinds selected from methylating agents and phenols are subjected to
Production of cresol or xylenol in which the m-position or the p-position is methylated by simultaneously contacting a solid catalyst under a condition of MPa or more and performing at least two kinds of reactions selected from a methylation reaction, a transmethylation reaction, and an isomerization reaction. Is the way. The present invention further provides a methylation reaction and a transmethylation reaction in which the raw material phenol and at least two selected from a methylating agent and a phenol are brought into contact with a solid catalyst at 350 to 700 ° C. and 5 MPa or more. And a method for producing cresols or xylenols in which at least one reaction selected from isomerization reactions is performed.

In general, a method for introducing a methyl group into a phenol skeleton includes (1) a methylation reaction of a raw material phenol having a replaceable hydrogen with a methylating agent such as methanol, and (2) a methylation reaction. A transmethylation reaction of a raw phenol having hydrogen and a methylphenol having at least one methyl group is known. In addition, as a method for producing methylated cresol or xylenol at the m-position or the p-position, (3) isomerization reaction of methylphenols having one or more methyl groups is known. The above three reactions all take place in the presence of a catalyst such as a solid acid catalyst. Even if any of the reactions can be prioritized by selecting the starting materials and reaction conditions, the above three reactions are simultaneously performed.
Two reactions often occur in parallel. In particular, the methylation reaction of phenols has strong o- and p-orientation,
In order to produce cresol or xylenol in which the m-position or the p-position is methylated, the reaction conditions must be strict, and the above three reactions often occur in parallel. However, even if the reaction conditions are strict, although the production ratio of the m-form is relatively low, the separated o-form can be reused as a raw material for isomerization or transalkylation.

According to the present invention, at least one of the above-mentioned methylation, transmethylation and isomerization reactions is carried out under specific conditions in the presence of a solid catalyst to obtain the m-position or the m-position. It is for producing cresol and / or xylenol (hereinafter, also referred to as mp-CXs) in which the p-position is methylated. As a solid catalyst, an inorganic substance is preferable instead of an organic substance because the reaction temperature becomes a high temperature of 200 ° C. or higher,
Specifically, solid acid catalysts such as alumina, silica, silica-alumina, zeolite, phosphate, and sulfate are preferred.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. First, a method for producing mp-CXs by a methylation reaction (including a transmethylation reaction) between a raw material phenol and a methylating agent will be described. The starting phenols include at least one starting phenol selected from phenol, cresols having a substitutable hydrogen at the m-position or the p-position, and anisole. Preferably, it is phenol or o-cresol. As the methylating agent, at least one selected from anisole, cresol, xylenol, trimethylphenol and methanol
There is one type of methylating agent (however, the starting phenols and the methylating agent are not the same). Here, when the methylating agent is other than methanol, a methylation reaction such as a transmethylation reaction occurs.

In the case of a methylation reaction using methanol, if phenol is used in excess of methanol, it is economical because there is no need to recover unreacted methanol in a subsequent step. Specifically, phenols / methanol =
It is preferably from 20/1 to 1/1 (molar ratio), more preferably from 5/1 to 1/1 (molar ratio). In the case of a methylation reaction (transmethylation reaction) using a methylating agent other than methanol, the use ratio of the reaction raw materials is not limited, but the molar ratio of methyl group / phenol ring is 1 to 2/1.
It is good to set in the range which becomes.

In the case of an isomerization reaction (including a transmethylation reaction), at least one selected from anisole, cresol, xylenol and trimethylphenol is used.
Species phenols are used as raw materials and there is no clear distinction from methylating agents and the like. Phenols as raw materials are o
-50 w of cresol, 2,6-xylenol and anisole
Those containing at least t% are preferred. Note that anisole is a reaction for transferring a methyl group within a molecule or between molecules, and thus is included in an isomerization reaction (including a transmethylation reaction).

The above-mentioned methylation reaction, isomerization reaction, and transmethylation reaction (these reactions are sometimes collectively referred to as the present reaction because these reactions cannot be clearly distinguished) are performed at 350 ° C. or higher on a solid catalyst. Can be produced in parallel by contacting with each other, so that one of the raw material phenols, methylating agent and phenols
The reaction can be carried out using one or more species. However, when the methylating agent is methanol and when the starting phenol is phenol, the reaction is carried out using two or more kinds. Thus, the methylating agent is methanol,
Except for the case where the raw material phenol is phenol, the raw materials used may be used alone or mixed at an arbitrary ratio. These reactions may be used alone or in combination to form a phenol ring with 1 to 5
It is possible to introduce one methyl group.

The reaction temperature of the above reaction must be 350 ° C. or higher. Reaction temperature 200 ° C ~ 35
In the range of 0 ° C., methylation at the o-position proceeds preferentially,
As the temperature increases, the methylation at the m- and p-positions takes precedence. In order to synthesize cresol and xylenol in which the m-position or the p-position is methylated, which is the object of the present invention, 350 ° C. or more is required. At a high temperature of 700 ° C. or more, demethylation from the phenol ring takes precedence. Therefore, the reaction temperature is 350 ° C to 700 ° C, preferably 400 ° C to 5 ° C.
00 ° C. Incidentally, the present invention is o-cresol or 2,6-
In order to synthesize xylenol, we do not care about yield,
This can be applied when importance is placed on the catalyst life.

The pressure of this reaction for introducing a methyl group into a carbon atom constituting the ring of the phenol ring is such that under normal pressure conditions in which the catalyst surface comes into contact with the gas phase, carbides precipitate on the catalyst surface, so that the catalytic activity decreases with time. I do. This tendency is particularly remarkable at 350 ° C. or higher where the methylation of the m-position and the p-position to the phenol skeleton takes precedence, so that the methylation reaction of the m-position and the p-position to the phenol skeleton is practically difficult in the gas phase. It is. However, when the reaction pressure is increased and the catalyst surface comes into contact with a fluid having a higher density than the gas phase, the carbide deposited on the catalyst surface is washed away by the high-density fluid, so that the decrease in activity over time is suppressed. Specifically, in any of the methylation reaction, transmethylation reaction, and isomerization reaction, deterioration with time of the solid acid catalyst can be suppressed at 5 MPa or more, and preferably 10 MPa.
That is all. The higher the reaction pressure, the more the deterioration of the catalytic activity with time can be suppressed. However, an ultra-high pressure of 30 MPa or more is not economical because the equipment construction cost becomes high.

This reaction can be carried out by a flow system or a batch system.
Are more economical to use in circulation. High for flow-through type
In SV, methylation reaction, transmethylation reaction, isomerization
The efficiency of the reaction decreases. Also, low SV reduces productivity
It is not economical. Therefore, the LHSV value is 0.1
~ 20h^-1And more preferably 0.5 to 5 hours ^-1
It is.

The reaction mixture obtained in this reaction is advantageously separated by distillation in the order of the boiling points. Water, which is the lowest boiling fraction, is removed out of the reaction system, and phenol can be reused as raw phenol. The next fraction, o-cresol, can be reused as a raw material for a methylation or transmethylation reaction. Next, m-cresol, p-cresol, and 2,6-xylenol can be recovered as the same fraction. Subsequently, 2,4-xylenol and 2,5-xylenol are recovered as the same fraction, and 3,5-xylenol, 2,3-xylenol and 3,4-xylenol are recovered as the same fraction. it can. Trimethylphenols, which are higher boiling fractions, can be reused as transmethylation raw materials. Further, the reaction mixture obtained in this reaction can be recovered by mixing with a tar acid fraction from coal tar.

[0017]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited by these examples. In the examples, “%” represents “mol%” unless otherwise specified. In the table, C represents cresol, X represents xylenol, and TMP represents trimethylphenol.

EXAMPLE 1 An inner diameter of 13 mm and an height of 1 with an electric heater attached to the outside.
A 50 mm stainless steel cylindrical reactor was filled with 20 ml (18 g) of a γ-alumina catalyst (N612N manufactured by JGC Chemicals) and phenol / methanol = 2/1 (molar ratio), and the reaction raw material was adjusted to 20 ml with a metering pump. / H and fed into the reactor to perform a methylation reaction. At this time, the reaction temperature was adjusted to 350 ° C. by an electric heater, and the pressure was adjusted to 10 MPa by a control valve at the outlet of the reactor. Table 1 shows the result of gas chromatography analysis of the composition of the residue obtained by removing water and phenol from the reaction mixture by distillation.

Examples 2 to 5 The same operation as in Example 1 was performed except that the reaction temperature was set at 400 ° C., 500 ° C., 600 ° C., and 700 ° C. Table 1 shows the results of gas chromatography analysis of the composition of the residue obtained by removing phenol from the reaction mixture by distillation.

Comparative Examples 1 and 2 The same operation as in Example 1 was performed except that the reaction temperature was set at 300 ° C. and 750 ° C. Table 1 shows the results of gas chromatography analysis of the composition of the residue obtained by removing phenol from the reaction mixture by distillation. As shown in Table 1, when the reaction temperature is low, the number of compounds in which the o-position is methylated, such as 2,6-xylenol, increases. When the reaction temperature is high, the demethylation reaction proceeds, and as a result, the phenol conversion rate decreases. I understand.

[0021]

[Table 1]

EXAMPLE 6 An inner diameter of 13 mm and an height of 1 with an electric heater attached to the outside.
20 ml (18 g) of a silica-alumina catalyst (N632L, manufactured by JGC Chemicals) in a 50 mm stainless steel cylindrical reactor
And phenol / 2,6-xylenol = 1/1
(Mole ratio) 20m
At 1 / h, the mixture was fed into the reactor to perform a transmethylation reaction. At this time, the reaction temperature was adjusted to 400 ° C. by an electric heater, and the pressure was adjusted to 5 MPa by a control valve at the outlet of the reactor.
The reaction mixture was collected over time, and its composition was analyzed by gas chromatography to determine the conversion of 2,6-xylenol from the content of 2,6-xylenol. Table 2 shows the results.

Examples 7 to 9 Same as Example 6 except that the reaction pressure was set to 10 MPa, 20 MPa, and 30 MPa. Table 2 shows the results.

Comparative Examples 3 and 4 The procedure was the same as in Example 6, except that the reaction pressure was 0.1 MPa and 3 MPa. Table 2 shows the results. In Table 2, the yield is expressed as (mC + pC + 2,4-X + 2.5 in the reaction mixture).
-X + 2,3-X + 3,5-X + 3,4-X) / (Phenol +
2,6-X) × 100.

[0025]

[Table 2]

EXAMPLE 10 An inner diameter of 13 mm with an electric heater attached to the outside, and a height of 1
In a 50 mm stainless steel cylindrical reactor, 20 ml of silica-alumina catalyst (N632HN manufactured by JGC Chemicals) (18
g) and phenol / anisole = 1/1 (molar ratio), and the reaction raw material was adjusted to 20 ml / h with a metering pump.
And supplied to the reactor to perform an isomerization reaction. At this time, the reaction temperature was adjusted to 500 ° C. with an electric heater, and the pressure was adjusted to 10 MPa with a control valve at the outlet of the reactor. Table 3 shows the result of gas chromatography analysis of the composition of the residue obtained by removing phenol from the reaction mixture by distillation.

Example 11 An inner diameter of 13 mm and an height of 1 with an electric heater attached to the outside
In a 50 mm stainless steel cylindrical reactor, 20 ml of silica-alumina catalyst (N632HN manufactured by JGC Chemicals) (18
g), phenol / o-cresol / trimethylphenol = 2/3/1 (molar ratio), and feed the reaction raw material into the reactor at a rate of 20 ml / h using a quantitative pump to perform a transmethylation reaction. Was. The reaction temperature at this time was adjusted to 450 ° C. with an electric heater, and the pressure was adjusted to 10 MPa with a control valve at the outlet of the reactor. Table 3 shows the result of gas chromatography analysis of the composition of the residue obtained by removing phenol from the reaction mixture by distillation.

Example 12 An inner diameter of 13 mm and an height of 1 with an externally provided electric heater.
A 50 mm stainless steel cylindrical reactor was charged with 20 ml (18 g) of a γ-alumina catalyst (N612N manufactured by JGC Chemicals), and the reaction was adjusted to anisole / o-cresol / trimethylphenol = 1/2/1 (molar ratio). The raw material was supplied into the reactor at a rate of 20 ml / h by a metering pump, and an isomerization reaction and a transmethylation reaction were simultaneously performed. At this time, the reaction temperature was adjusted to 400 ° C. by an electric heater, and the pressure was adjusted to 10 MPa by a control valve at the outlet of the reactor. Table 3 shows the result of gas chromatography analysis of the composition of the residue obtained by removing phenol from the reaction mixture by distillation.

Example 13 An inner diameter of 13 mm and an height of 1 with an electric heater attached to the outside
A 50 mm stainless steel cylindrical reactor was charged with 20 ml (18 g) of a γ-alumina catalyst (N612N manufactured by JGC Chemicals), and phenol / methanol / o-cresol / 2,6
-Xylenol = 2/1/1/1 (molar ratio) The reaction raw material was fed into the reactor at a rate of 20 ml / h by a metering pump, and the methylation reaction and the transmethylation reaction were simultaneously performed. At this time, the reaction temperature was adjusted to 400 ° C. by an electric heater, and the pressure was adjusted to 10 MPa by a control valve at the outlet of the reactor. Table 3 shows the result of gas chromatography analysis of the composition of the residue obtained by removing water and phenol from the reaction mixture by distillation.

[0030]

[Table 3]

[0031]

According to the present invention, cresol and xylenol in which the m-position or the p-position is methylated can be produced economically under reaction conditions in which the catalytic activity does not decrease over time. The present invention is also effective for producing or co-producing cresol and xylenol substituted at the o-position depending on the purpose.

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Claims (4)

[Claims] 1. A raw material phenol selected from phenol, cresols having hydrogen substitutable at m-position or p-position and anisole, and selected from anisole, cresol, xylenol, trimethylphenol and methanol. Contacting at least one methylating agent (provided that the starting phenol and the methylating agent are not the same) with the solid catalyst at 350 to 700 ° C. and 5 MPa or more; A method for producing cresol or xylenol in which is methylated. 2. At least one selected from anisole, cresol, xylenol and trimethylphenol.
A method for producing cresol or xylenol in which the m-position or the p-position is methylated, wherein a kind of phenol is brought into contact with a solid catalyst at 350 to 700 ° C and 5 MPa or more. 3. A raw material phenol according to claim 1 and at least two selected from a methylating agent and a phenol according to claim 2 are contacted with a solid catalyst at 350 to 700 ° C. and 5 MPa or more. A method for producing cresol or xylenol in which the m-position or the p-position is methylated, wherein at least two kinds of reactions selected from a methylation reaction, a transmethylation reaction and an isomerization reaction are simultaneously performed. 4. A raw material phenol according to claim 1 and at least two selected from a methylating agent and a phenol according to claim 2 are contacted with a solid catalyst at 350 to 700 ° C. and 5 MPa or more. And producing at least one reaction selected from a methylation reaction, a transmethylation reaction and an isomerization reaction.