JPH0395136A - Production of methyl isobutyl ketone - Google Patents

Abstract

PURPOSE:To obtain the high-purity objective substance by feeding a reaction solution of acetone and H2 to a first distillation column, recycling unreacted acetone from the top of the column, bringing a liquid at the bottom of the column into contact with H2, sending the liquid to a second distillation column, distilling low boiling by-products from the top of the column and distilling the liquid at the bottom of the column. CONSTITUTION:Fresh acetone from a line 1, acetone recycled from a first distillation column 9 through a line 3 and H2 from a line 2 are fed to a reactor 4 and reacted in the presence of a catalyst (e.g. niobic acid and Pd) to form MIBK. The reaction solution is sent to a gas-liquid separator 6, H2 is purged and then a liquid at the bottom of the column, consisting essentially of MIBK is obtained from the first distillation column 9. The liquid is introduced to a liquid-liquid separator 11, an oily layer and H2 from a line 15 are fed to 4 hydrogenating rector 14 and mesityl oxide contained in the liquid is converted into MIBK. The reaction solution is successively passed through a second distillation column 17 and a third distillation column 20 and high-purity MIBK is obtained from a line 22 in high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing methyl isobutyl ketone through a stage reaction using acetone and hydrogen as raw materials.

Methyl isobutyl ketone (hereinafter sometimes referred to as rMIBKj) is useful as a raw material for organic solvents, paints, stabilizers, and the like.

BACKGROUND ART MIBK is usually produced industrially using acetone and hydrogen as raw materials by the following three-step process.

Condensed Acetone Diacetone Alcohol Dehydrated Mesityl Oxide Hydrogenated Methyl Isobutyl Ketone The feature of this three-step process is that the steps of condensation, dehydration, and hydrogenation shown in the above formula are carried out sequentially. First, acetone is converted to 10% by using a solid base catalyst such as barium hydroxide.
Diacetone alcohol is synthesized by reacting at ~20'C in the liquid phase at normal pressure, and then the diacetone alcohol obtained by condensation is reacted in the liquid phase in the presence of an acid catalyst such as sulfuric acid or phosphoric acid. The mixture is heated to 100 to 120'C to carry out a dehydration reaction to obtain mesityloquindo. Subsequently, this mesityl oxide is separated and purified, and then hydrogenated in the presence of a Raney nickel catalyst or the like to produce MIBK.

This method, which is widely used industrially, involves three reaction steps: condensation, dehydration, and hydrogenation, and in each step, intermediates such as diacetone alcohol and mesityl oxide are separated and purified. is required and the operation is complicated. Furthermore, since the condensation reaction from acetone to diacetone alcohol is an equilibrium reaction, there is a problem that the conversion rate is as low as about 15%.

For this reason, studies are being conducted to produce MIBK in one step from acetone and hydrogen. This method is advantageous in terms of equilibrium, can increase the raw material conversion rate per pass, and is economically advantageous compared to the three-stage method.

Several processes have been proposed as methods for producing MIBK using such a one-step method (for example, Bul
letein of The Japan Petro
leumInstitute 16 (1) P55～
59, Hydrocarbon Processin
g1985 Dec. P51-52, Hydro
ocarbon Processing 1977No.
v. P184, Chemical Engine
ering 1968 May P108), all of them only disclose a general method using a combination of distillation columns for the purification step after the reaction.

Problems to be Solved by the Invention The present invention aims to obtain high-purity MIBK in a high yield in a method for producing MIBK using acetone and hydrogen as raw materials.

Means for Solving the Problems> As a result of intensive studies to achieve the above object, the present inventors discovered that mesityl oxide (CH3COCHC(CH3)
2) inevitably occurs as a by-product, resulting in wasted raw materials and
Since the reaction yield decreases and furthermore, the boiling point of mesityl oxide is 129°C, which is close to the boiling point of M I B K, 117°C, purification by distillation, which is conventionally carried out, is not enough. It has been found that it is difficult to sufficiently separate it from MIBK, and this results in a decrease in the purity of the product MIBK. Therefore, we further investigated the method of removing the mesityl oxide and found that prior to the distillation of JiIBK, the mesityl oxide contained in MIBK is converted to MIBK by reacting with hydrogen, resulting in a decrease in the reaction yield. The present invention was achieved based on the knowledge that the purity of the product MIBK can be maintained at a high level without the above-mentioned problems.

In other words. The present invention provides a method for producing methyl isobutyl ketone from acetone and hydrogen, including a step of supplying acetone and hydrogen to a reactor having a +a+ catalyst and reacting the acetone and hydrogen to produce methyl isobutyl ketone. (The reaction liquid obtained in step al is supplied to the first distillation column, and the liquid obtained from the top of the column, whose main component is unreacted acetone, is recycled to the reactor used in step (a) above, and is sent to the bottom of the column. Step of obtaining a liquid containing methyl isobutyl ketone as a main component, fcl The liquid containing methyl isobutyl ketone as a main component obtained in the above (bl step) is brought into contact with hydrogen in the presence of a hydrogenation catalyst to obtain the methyl A step of converting mesityl oxide contained in a liquid containing isobutyl ketone as a main component to methyl isobutyl ketone, (d) The liquid obtained in the above FCL step is supplied to the second distillation column, and a light distillation is carried out from the top of the column. A step of distilling off by-products and obtaining a liquid containing methyl isobutyl ketone as the main component at the bottom of the column, te+ The liquid containing methyl isobutyl ketone as the main component obtained in step f(1) above is transferred to the third distillation column. This relates to a method for producing methyl isobutyl ketone, which is characterized by comprising the following steps:

The method of the present invention will be explained below with reference to the flowchart shown in FIG.

Fresh acetone supplied from line 1 and
A mixture of acetone recycled from distillation column 9 through line 3 and hydrogen gas supplied from line 2 are led to reactor 4 .

The reactor 4 is filled with a catalyst, and MIBK is produced by the reaction of acetone and hydrogen in the presence of the catalyst. In addition, isopropanol, mesityl oxide, diisobutyl ketone, methyl isobutyl carbinol, water, etc. are produced as by-products. Catalysts in the reactor 4 include acid type ion exchange resin and palladium-carbon (for example, see Teuts Patent No. 1238453), a catalyst in which palladium is supported on zirconium phosphate (for example, Japanese Patent Publication No.
6994), a catalyst in which palladium is supported on H-type zeolite (for example, see Japanese Patent Publication No. 46-2643), a catalyst consisting of niobic acid and palladium (for example, see Japanese Patent Application Laid-Open No. 61-78745) ) etc. are used.

Although reaction conditions vary depending on the catalyst used, the reaction temperature is usually 100 to 200°C and the reaction pressure is 5 to 50 atmospheres.

The reaction liquid discharged from the reactor 4 passes through a line 5 and is led to a gas separator 6, where unreacted hydrogen gas is purged from a line 7.

The reaction liquid from which unreacted hydrogen gas has been removed is led to a first distillation column 9 through a line 8.

In the first distillation column 9, unreacted acetone is distilled off at the top of the column.
A liquid containing mainly MIBK is extracted from the bottom of the column.

Unreacted acetone extracted from the top of the column passes through line 3 and is recycled to reactor 4 again. The operating conditions of the first distillation column 9 are not particularly limited, but usually the bottom temperature is 80 to 110°C and the top pressure is 700 to 800 mm.
It is Hg.

On the other hand, the liquid mainly composed of MIBK extracted from the bottom of the first distillation column 9 passes through the line 10 to the liquid-liquid separator 11.
The water produced by the reaction is separated into a liquid consisting of an oil layer containing MIBK, and the water is purged out of the system through line 12.

After water has been separated, a liquid consisting of an oil layer containing MIBK is led to a hydrogenation reactor 14 through a line 13. In the hydrogenation reactor 14, hydrogen supplied from the line 15 reacts with mesityl oxide contained in the liquid led from the line 13 in the presence of a hydrogenation catalyst, and menthyl oxide is converted into M
Converted to I B K. Derived from line 13,
The content of menthyl oxide contained in the liquid varies depending on the catalyst and reaction conditions used in the reactor 4, but it is 0.
It is about 5 to 5% by weight. As the hydrogenation catalyst for the hydrogenation reactor 14, a palladium-based catalyst, a nickel-based catalyst, or the like is used, and preferably a palladium-based catalyst is used. The hydrogenation reaction conditions are usually a reaction temperature of 50 to 150°C and a reaction pressure of 2 to 20 atmospheres. By carrying out the reaction under such conditions, mesityloxytoxin is almost completely converted to MIBK.

By converting mesityl oxide into MIBK in the hydrogenation reactor 14, the yield of MIBK is improved, and mesityl oxide contained in the purified X1 BK obtained through the line 22 is eliminated. There is an advantage that the purity of MIBK is improved.

The liquid discharged from the hydrogenation reactor 14 passes through line 16 to the second
It is guided to a distillation column 17. The operating conditions of the second distillation column are not particularly limited, but usually the bottom temperature is 110~
130'C, top pressure 700-800 mmHg
It is. Light boiling by-products such as isopropanol produced in the reactor 4 are distilled off from the top of the second distillation column 17 through a line 18. The liquid at the bottom of the column passes through line 19 to the third
It is guided to a distillation column 20 and is extracted from the top of the third distillation column 20 through a line 22 to extract high-purity M I B K.

On the other hand, by-products such as methyl isobutyl carbinol and diisobutyl ketone are discharged from the bottom of the third distillation column 20 through a line 21.

The operating conditions of the third distillation column are not particularly limited, but are usually a bottom temperature of 150 to 180°C and a top pressure of 700 to 800 mmHg.

As explained above, after recovering unreacted acetone in the first distillation column 9, the by-product mesityl oxide is converted to MIBK in the hydrogenation reactor 14, and then in the second and third distillation columns.
By performing the distillation, highly pure M I B K can be obtained in good yield.

Examples> The present invention will be explained below with reference to Examples, but the scope of the present invention is not limited thereby.

Example 1 Catalyst obtained by immersing niobic acid (manufactured by CBMM, cylindrical) in an aqueous solution of palladium chloride, reducing it with hydrazine, and calcining it at 300°C (palladium supported amount: 0.1% by weight)
40 ml was filled into a vertically arranged reaction tube with an inner diameter of 28 mm, and 158 g/hr (LHSV=5) of aceto7 was added under conditions of a temperature of 150°C and a pressure of 20 kg/cm.
, hydrogen was introduced into the reactor at a supply rate of 256 Nml/min, and the reaction was carried out to obtain a reaction solution having the composition shown in Table 1.

The reaction solution was analyzed by gas chromatography and Karl Fischer.

Table 1 Reaction liquid composition After distilling the reaction liquid obtained in the above reaction and distilling off unreacted acetone, the distillation residue was separated into an oil layer and a water layer. I got it.

Note that the distillation conditions are as follows.

Distillation column theoretical plate number: 10 plates Reflux ratio: 1. ○ Top pressure: 620 mmHg Table 2 Composition of liquid in oil layer
．． 3%) was introduced into a vertically arranged reaction tube with an inner diameter of 28 mm under conditions of a temperature of 150'C and a pressure of 10 kg/cm2 at a supply rate of 64 g/hr (LHSV=4) and 4QNml/min of water. , a hydrogenation reaction was performed.

The composition of the reaction solution obtained by this reaction was as follows.

Table 3 Composition of hydrogenation reaction solution 600g of the solution obtained in the above hydrogenation reaction was mixed with 20 theoretical plates.
The mixture was charged into a distillation column, and distillation was carried out under the conditions of a reflux ratio of 2.5 and a column top pressure of 300 mmHg. When each distilled fraction was separated and analyzed by gas chromatography, the fraction containing MIBK as the main component was collected, and its weight was 502 g, and its purity was 99.6% by weight. Met.

Comparative Example 1 Using 600 g of the liquid before being subjected to the hydrogenation reaction in Example 1, distillation was carried out under the same conditions as for the liquid after the hydrogenation reaction in Example 1.

When each distilled fraction was separated and analyzed by gas chromatography, the fraction containing MIBK as the main component was collected, and its weight was 470 g, and its purity was 98.5%. can be. It contained 1.1% mesityl oxide.

<Effects of the Invention> As explained above, according to the present invention, highly purified methyl isobutyl ketone can now be obtained in good yield.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a preferred embodiment of the present invention. 9. First distillation column 11: Liquid-liquid separator 12: Purge water flow 14: Hydrogenation reactor 15. Hydrogen flow 17:
Second distillation column 18: Light boiling byproduct stream 20: Third distillation column 2
1: By-product stream 22: High purity MIBK stream 5, 8,
10. 13. 16, 19: Above the pipeline

Claims (1)

[Claims] (1) In a method for producing methyl isobutyl ketone from acetone and hydrogen, (a) supplying acetone and hydrogen to a reactor having a catalyst;
a step of reacting acetone and hydrogen to produce methyl isobutyl ketone; (b) supplying the reaction solution obtained in step (a) above to the first distillation column, and converting unreacted acetone obtained from the top of the column as the main component; A step of recycling the liquid obtained in step (a) above to the reactor to obtain a liquid containing methyl isobutyl ketone as a main component at the bottom of the column, (c) recycling the methyl isobutyl ketone obtained in step (b) above. a step of contacting the liquid containing the main component with hydrogen in the presence of a hydrogenation catalyst to convert mesityl oxide contained in the liquid containing methyl isobutyl ketone as the main component to methyl isobutyl ketone; (d) the above ( A step of supplying the liquid obtained in step c) to a second distillation column, distilling off light-boiling byproducts from the top of the column, and obtaining a liquid containing methyl isobutyl ketone as the main component at the bottom of the column; (e) the above step; A step of supplying the liquid containing methyl isobutyl ketone as a main component obtained in step (d) to a third distillation column to obtain highly pure methyl isobutyl ketone from the top of the column. , a method for producing methyl isobutyl ketone.