JPH0438736B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a method of combining phenol or/and orthocresol and methanol in the presence of a metal oxide.
The present invention relates to a method for economically separating a main product from a reaction product in a method for producing an ortho-methylated phenol compound through gas phase contact using a fluidized bed reaction.

The ortho-methylated phenol compound, such as 2,6-xylenol, produced by the method of the present invention is a raw material for polyphenylene oxide and 2,6-xylidine, which is a raw material for agricultural chemical ingredients; Orthocresol is a raw material for pharmaceutical and agricultural products, and both are useful as industrial raw materials.

(Prior Art) A method for producing an ortho-methylated phenol compound by bringing phenol or/or orthocresol into contact with methanol in the gas phase is known, and is carried out using a fixed bed reactor.

Generally, when exothermic reactions are carried out using a fixed bed reactor, local heating tends to occur, which is extremely disadvantageous in terms of reaction, so methods using a fluidized bed reactor have been proposed (especially Kosho 52-
46930).

Famous examples of practical applications of the fluidized bed method include the fluid catalytic cracking (FCC) process and the acrylonitrile production process, and the catalyst used must contain particles of 44μ or less to facilitate fluidity.
A mixing ratio of 20 to 40% is considered appropriate.

Therefore, one of the drawbacks of the fluidized bed method is the constant catalyst loss of fine powder particles, and it is extremely important in the fluidized bed process how advantageously the dispersed catalyst can be treated.

As a method for removing the scattered catalyst, it is common sense to remove it from the condensate of the reaction product using a precoat filter, but this method is complicated and cannot be said to be an industrially advantageous process. In the example of the acrylonitrile production process, a method has been proposed in which preliminary washing with hot water is performed as a pre-process of washing with sulfuric acid to collect high-boiling substances and catalyst particles in the gas, but a method for producing ortho-methylated phenol compounds has been proposed. If you try to apply it to other countries, the equipment would be huge and it would be impractical.

In the process of producing ortho-methylated phenol compounds, if the scattered catalyst from the fluidized bed reactor is introduced untreated into the separation column without being discharged to the outside of the system midway, the final product column 2,
The fine powder catalyst will be discharged from the bottom of the 6-xylenol tower, but the catalyst will accumulate inside the separation tower, significantly reducing the separation performance. Contamination of the exchanger causes a reduction in heat transfer ability, making it virtually impossible to continue continuous operation.

(Problems to be Solved by the Invention) As mentioned above, when producing an ortho-methylated phenol compound using a fluidized bed method, there is no established industrial process for treating the scattered catalyst. be.

(Means for Solving the Problems) As a result of intensive studies to solve the above-mentioned problems, the present inventors have completed the present invention, which is industrially extremely advantageous.

That is, the present invention involves reacting phenol or/and orthocresol with methanol in the presence of a metal oxide to produce ortho-methylated phenolic compounds, high-boiling byproducts, unreacted methanol, and a reaction containing phenol. After separating gaseous by-products from the mixture, separating unreacted methanol and produced water from the resulting mixture, and further separating phenol by distillation, orthocresol and 2,6-xylenol are separated, and then 2,6-xylenol is separated. ,6
- In a method for producing an ortho-methylated phenol compound in which xylenol is separated by distillation, the reaction is carried out by a fluidized bed reaction, and high-boiling substances are separated by distillation before the phenol is separated by distillation, so that the fine powder catalyst is scattered from the reactor. This is a method for producing an ortho-methylated phenol compound, which is characterized in that the compound is discharged from the system together with a high-boiling point substance.

First, a conventional process will be specifically explained using examples of manufacturing 2,6-xylenol and orthocresol shown in FIG.

Phenol and methanol react in the gas phase in the presence of a catalyst in reactor 1, and apart from the main products 2,6-xylenol and orthocresol, small amounts of 2,4-xylenol, 2,5-xylenol and 2 , 4,6-trimethylphenol, etc.
and high-boiling products are formed, forming a mixture with unreacted methanol, phenol and produced water.

After this hot gaseous mixture is cooled in a heat exchanger 2, it is sent to a gas separation tower 3 to separate the gaseous by-products and the mixture. Here, the gaseous by-products include hydrogen gas, carbon monoxide, carbon dioxide gas, methane gas, and the like. Water passes from the bottom of the gas separation tower 3 through a line 4 and is distilled and separated in a dehydration tower 5.

Methanol and water distilled from the top of the dehydration tower 5 pass through a line 6 and are distilled and separated in a methanol tower 7. The recovered methanol distilled from line 8 at the top of the methanol column is recycled and reused in the reaction system.

On the other hand, the bottom liquid of the dehydration tower 5 passes through a line 9 to a phenol tower 10, where unreacted phenol is separated by distillation. The recovered phenol distilled from the line 11 at the top of the phenol column is recycled and reused in the reaction system together with the recovered methanol. Phenol tower 1
The bottom liquid of 0 passes through line 12 and is distilled and separated in orthocresol column 13 as orthocresol product. The bottom liquid of the orthocresol tower 13 is
2,6-xylenol is distilled and separated as a product in a 2,6-xylenol column 16 through a line 15.

From the bottom of the 2,6-xylenol tower 16,
High boiling products including 2,4,6-trimethylphenol, 2,4-xylenol, 2,5-xylenol, etc. are discharged.

As the distillation column, a bubble column, a tray column, and a packed column are usually used. In addition, dehydration towers and methanol towers are usually operated under normal pressure, phenol towers, orthocresol towers,
2,6-xylenol towers are often operated at reduced pressure.

The conventional manufacturing method for 2,6-xylenol is as described above, and in some cases, when separating orthocresol and 2,6-xylenol, it is also possible to perform extraction separation using aliphatic saturated hydrocarbons, etc. It is.

When a fluidized bed system is adopted as a reactor for the above-mentioned 2,6-xylenol production method, a small amount of catalyst fine powder scattered from the reactor impairs the operational performance of the distillation column.

That is, orthocresol containing catalyst fine powder,
2,6-xylenol and the above-mentioned high-boiling products can be produced in a phenol tower, an orthocresol tower, a 2,6-xylenol
- When introduced into the xylenol column, it stagnates in areas of the column where the liquid flows poorly, and catalyst fine powder accumulates, deteriorating separation performance and promoting fouling of the reboiler transfer surface of the distillation column, resulting in insufficient heat transfer ability. In addition, in some cases, there was a drawback that continued operation was impossible.

As mentioned above, when producing ortho-methylated phenolic compounds by fluidized bed reaction, it is extremely important to establish a separation process for the fine powder catalyst that is scattered from the reactor. It was in an unestablished state.

The present invention is a method for producing an ortho-methylated phenol compound by a fluidized bed reaction, in which a high-boiling point substance is distilled off before phenol is distilled off. Since it is discharged to the outside of the system along with boiling point substances, it can be produced industrially with great advantage.

Catalysts applicable to the present invention do not need to be specified, and all catalysts used in the synthesis of ortho-methylated phenol compounds are covered. For example, metal components include iron, vanadium, manganese, magnesium, chromium, and indium, singly or in combination, and in addition, alkali metals, alkaline earth metals, rare earth metals, etc. are added to these components. There is.

In the case of the present invention, the molar ratio of methanol to phenol or/and orthocresol in the feedstock varies depending on the catalyst species, but ranges from 1:1 to 20
It is. Further, water vapor or an inert gas can be introduced as necessary, but in the case of water vapor, the molar ratio to phenol and/or orthocresol is preferably 1:0 to 15.

The reaction temperature varies depending on the catalyst type, but is between 250 and 600℃.
A range of is preferred.

The reaction can be carried out at normal pressure, reduced pressure or increased pressure.

In the reaction of the present invention, for example, anisole, 2,4-xylenol, 2,5-xylenol, etacresol, para-cresol, 2,4,
6-Trimethylphenol and high-boiling substances with a boiling point higher than 2,4,6-trimethylphenol are produced as by-products. Refers to a substance that has a boiling point. The fine powder scattered from the fluidized bed reactor varies depending on the performance of the reactor, but the fine powder referred to in the present invention is particles of 30 μm or less, and in practice, many particles are within this range.

In the separation process of the fine catalyst in the present invention, water is distilled and separated in a dehydration tower, and then the phenolic mixture containing the fine catalyst is discharged to the outside of the system as a high-boiling substance containing the fine catalyst in a high-boiling substance separation tower. There are two methods: a method in which the methanol and phenol mixture containing the fine catalyst from the bottom of the gas separation tower is discharged to the outside of the system as a high boiling substance containing the fine catalyst in the high boiling point substance separation tower. It exists as a separation process prior to separating phenol by distillation.

(Effects of the Invention) In the present invention, the fine powder catalyst can be removed from the system together with high-boiling substances before the phenol compound is separated by distillation. Contamination of the heat exchanger can be prevented, and there is no need to increase the heat exchanger capacity. In other words, stable, continuous operation for a long period of time is possible.

(Example) The present invention will be explained below with reference to Examples.

Example 1 The experiment was carried out according to the flow sheet shown in FIG. Phenol and methanol are reacted in the presence of a metal oxide in a fluidized bed reactor 1', and the reaction product is cooled in a heat exchanger 2, passes through a line 4 from the bottom of a gas separation tower 3, and is transferred to a dehydration tower 5. After water is distilled off at the top of the dehydration tower 5, methanol and water distilled from the top of the dehydration tower 5 pass through a line 6 and are distilled off at a methanol tower 7, and the phenolic mixture containing the fine catalyst passes through a line 9. High boiling point substance separation column 1
9, and the high-boiling substances containing the fine catalyst are discharged to the outside of the system through line 20. The top liquid is rye 2
1, and is introduced into a phenol column 10, then an orthocresol column 13, and further introduced into a 2,6-xylenol column 16. An orthocresol product is obtained from line 14, and a 2,6-xylenol product is obtained from line 17.

As distillation columns, we used a packed column for the phenol column, an orthocresol column, and a tray column for the 2,6-xylenol column, but all of these columns did not reduce separation performance due to clogging, etc., and at the same time, the heating source of the distillation column It was possible to operate the heat exchanger without reducing its capacity.

Example 2 The experiment was carried out according to the flow sheet shown in FIG. Phenol and methanol are reacted in the presence of a metal oxide in a fluidized bed reactor 1', and the reaction product is cooled in a heat exchanger 2 and passed through a line 4 from the bottom of a gas separation column 3 to collect high-boiling substances. The high-boiling point substances, which are introduced into the separation column 19 and contain the finely divided catalyst, are discharged to the outside of the system through a line 20. Top liquid is line 2
1, water is distilled and separated in a dehydration tower 5, and then introduced into a phenol tower 10, then an orthocresol tower 13, and then a 2,6-xylenol tower 16.
An orthocresol product is obtained from line 14 and a 2,6-xylenol product is obtained from line 17.

As distillation columns, we used a packed column for the phenol column, an orthocresol column, and a tray column for the 2,6-xylenol column, but all of these columns did not degrade separation performance due to clogging, etc., and at the same time, the heating source of the distillation column It was possible to operate the heat exchanger continuously for a long period of time without decreasing its capacity.

The present invention is as described above, and by separating and discharging the fine powder catalyst scattered from the fluidized bed reactor in a high-boiling separation column, the distillation column in the next step is free from deterioration of separation performance due to clogging etc. This prevents a decrease in heat exchanger capacity and achieves highly stable operation.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing the conventional process for producing an ortho-methylated phenol compound, FIG. 2 is a flow sheet showing the production process of Example 1, and FIG. 3 is a flow sheet showing the manufacturing process of Example 2.

Claims (1)

[Claims] 1 Reacting phenol or/and orthocresol with methanol in the presence of a metal oxide to produce ortho-methylated phenol compounds, high-boiling byproducts and unreacted methanol,
Gaseous byproducts are separated from the reaction mixture containing phenol, unreacted methanol and produced water are separated from the resulting mixture, phenol is further separated by distillation, and orthocresol and 2,6-xylenol are separated. In the method for producing an ortho-methylated phenol compound in which 2,6-xylenol is then separated by distillation, the reaction is carried out by a fluidized bed reaction, and the high boiling point substance is further separated by distillation before the phenol is separated by distillation. A method for producing an ortho-ethylated phenol compound, which comprises discharging a fine powder catalyst scattered from a reactor to the outside of the system together with high-boiling substances.