JP2528866B2 - Acetic acid and methyl acetate production method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing acetic acid and methyl acetate from methanol and carbon monoxide as raw materials.

[Conventional technology]

Carbonylation of alcohol, that is, as a method of synthesizing a monocarboxylic acid by reacting alcohol with carbon monoxide, a cobalt compound such as cobalt acetate is used as a catalyst, and an iodine compound such as potassium iodide or methyl iodide is used. Used as a co-catalyst, 483-523K, 50-70MPa,
A high-pressure method in which an alcohol and carbon monoxide are reacted in a liquid state has been put into practical use.

In recent years, a liquid phase method of Japanese Patent Publication No. 47-3334 has been developed, which uses a rhodium complex catalyst and uses methyl iodide or hydrogen iodide as a cocatalyst, and the reaction is performed at a temperature of 448 to 518 K and a pressure of 1.0 to 3.0 MPa. The low-pressure method was put into practical use.

In this method, the reaction proceeds under remarkably mild conditions as compared with the above high-pressure method, and the yield of acetic acid is also based on carbon monoxide.
90% and 99% based on methanol, which is very high. Various methods for producing acetic acid and the like from alcohol and carbon monoxide by a vapor phase method have been studied, but no technique has been put to practical use so far.

[Problems to be Solved by the Invention]

The low-pressure method currently in practical use has the great disadvantage that rhodium, which is extremely expensive as a catalyst and is difficult to obtain in terms of resources, must be used, and at the same time, halogen compounds such as iodides are used as a promoter in a liquid phase. Corrosion of the equipment is severe because it is used under conditions. In order to withstand this corrosion, the device must be constructed of expensive materials such as Hastelloy.

Further, since acetic acid is circulated as a carrier for the catalyst and the co-catalyst, the utility consumption is large and there are various problems as an industrial manufacturing method.

On the other hand, in the gas phase synthesis method, the catalytic activity is generally low,
Since the catalyst has a short life and a low selectivity, the yields of acetic acid and methyl acetate are low, and the selectivity of acetic acid is lower than that of methyl acetate.

An object of the present invention is to provide a method for producing acetic acid and methyl acetate by vapor phase carbonylation of methanol, which has a high acetic acid yield.

Another object of the present invention is to provide a method for producing acetic acid and methyl acetate by vapor phase carbonylation of methanol, which has improved catalytic activity and high product yield.

Other objects of the present invention will be apparent from the following description.

[Means for solving the problem]

In the production of acetic acid by a gas-phase synthesis reaction, the production of methane is a factor in the decrease in the yield of acetic acid and the like, and when the raw material carbon monoxide and the like react with hydrogen, methane is produced. Therefore, it was said that the presence of hydrogen in the reaction system would lead to a decrease in the acetic acid yield, but the inventors of the present invention accidentally used a metallic nickel catalyst supported on a carbonaceous carrier in the repeated process of the experiment. As a result, it was discovered that the presence of a small amount of hydrogen in the reaction system unexpectedly increases the acetic acid yield, and the present invention was reached.

The method for producing acetic acid and methyl acetate according to the present invention comprises methanol and carbon monoxide at a pressure of 0.1 to 30 MPa and a pressure of 37 MPa.
At the temperature of 3 to 673 K, when acetic acid and methyl acetate are produced by gas phase reaction in the presence of a catalyst composed of metallic nickel supported on a carbonaceous support and a cocatalyst composed of a volatile halogen compound, It is characterized in that the reaction is carried out in the presence of hydrogen at 1 to 40 mol% of carbon oxide.

The method of the present invention is carried out in the vapor phase. It is desirable that the reaction is carried out under the condition that both the raw material and the product remain in the gas phase, but the reaction does not hinder even if a high-boiling substance such as alcohol or monocarboxylic acid is present in a liquid state. proceed.

The reaction temperature is in the range of 373 to 673K, preferably 423 to 573K.

The reaction pressure is in the range of 0.1 to 30 MPa, preferably 0.1 to 10 MPa.

The content ratio of methanol to carbon monoxide in the raw material may basically be a stoichiometric amount, but either may be present in excess.

In the process according to the invention, the molar ratio of methanol to carbon monoxide is preferably chosen in the range of 100: 1 to 1: 100, particularly preferably 10: 1 to 1:10.

The raw material carbon monoxide does not have to be pure, and the inclusion of some impurities is acceptable.

The catalyst used in the method of this invention comprises metallic nickel supported on a carbonaceous support.

As the carbonaceous carrier, activated carbon, carbon black, coke, etc. are used, or carbon-deposited silica, alumina, silica-alumina, etc. are used.
After the active ingredient nickel is supported on an inorganic carrier such as silica, alumina, or silica-alumina, carbon may be deposited.

The loading rate of metallic nickel is not particularly limited, but is preferably within the range of 0.1 to 40 wt%, particularly preferably 0.5 to 20 wt%.
It is selected within the range of%.

In the catalyst used in this invention, nickel and carbon are
Direct, intimate contact is important.

In the method of the present invention, a small amount of hydrogen is allowed to exist in the reaction system to accelerate the reaction.

Since the separation of hydrogen contained in industrially produced carbon monoxide is omitted or simplified, the industrial significance of this constituent factor is great.

The amount of hydrogen is 1 to 40 with respect to 100 mol of carbon monoxide.
It is selected in the range of 5 mol, preferably 5 to 30 mol.

In the method of the present invention, a volatile halogen compound such as iodine or bromine is allowed to be present as a cocatalyst in the reaction system together with the above catalyst and hydrogen.

As the halogen compound, alkyl iodide such as methyl iodide and alkyl bromide such as methyl bromide are suitable.

These halogen compounds are bound to the metallic nickel surface of the catalyst component during the reaction.

In order to make this bonding appropriate, it is sufficient to include a volatile halogen compound in the raw material stream, but it is desirable to carry out a halogenation treatment of the catalyst as a catalyst activation treatment.

In the method of the present invention, the presence of hydrogen in the reaction system enhances the cocatalyst action of the halogen compound, and improves both the reaction rate and the selectivity.

The amount of these cocatalysts is not particularly limited, but methanol
It is preferably selected within the range of 0.1 to 50 mol, particularly preferably within the range of 1 to 30 mol, relative to 100 mol.

A promoter may be present in the catalyst in order to further increase the reaction rate and suppress methane generation and nickel volatilization.

As suitable promoters, alkali metals, iron, copper, silver, molybdenum, chromium, tungsten, tin, vanadium, zinc, antimony, zirconium, lead, bismuth, magnesium and the like, or compounds of these metals are effective.

〔Example〕

Example 1 Commercially available granular activated carbon, "Shirasagi C" (trade name) manufactured by Takeda Yakuhin Kogyo Co., Ltd. was crushed and classified, and 100 g of fine granular activated carbon of 20 to 40 mesh obtained was nickel nitrate aqueous solution containing 2.6 g of metallic nickel. After being mixed with and thoroughly mixed with water, water was removed by evaporation, and the mixture was dried and kept at 393 K for 24 hours to be completely dried.

After this drying, it was heat-treated in a nitrogen atmosphere at 673K for 2 hours, and then reduced in a hydrogen stream at 673K for 2 hours, and then in a carbon monoxide atmosphere containing 1 vol.% Of methyl iodide. It was pretreated for 2 hours at 523K.

By this pretreatment, a catalyst having a ratio of the amount of supported nickel to the amount of iodine on the catalyst of 1.2 was obtained.

0.5 g of this catalyst was packed as a fixed catalyst bed in a pressure resistant reactor having an inner diameter of 4 mm.

This pressure resistant reactor was used for the experiment with the following conditions.

Feedstock composition ratio Carbon monoxide: Methanol: Methyl iodide = 500: 95: 5 Contact time W / F 5g-catalyst · h / mol (However, hydrogen is ignored.) Reaction temperature 523K Reaction pressure 1.1MPa Reaction system state After stabilization, the gaseous mixture flowing out of the reactor was cooled to 276 K or less by a gas cooler, and the obtained condensate and gaseous mixture were analyzed by gas chromatography.

In this experiment, the amount of hydrogen present in the reaction system was 0 (comparative example), (hereinafter, example) 30, relative to 500 mol of carbon monoxide.
The molar amount of each of 60, 100 and 140 was changed stepwise.

The reaction product composition corresponding to this change in the amount of hydrogen was as shown in the following table.

Reaction conditions Example 2 Commercially available granular activated carbon, BAC MQ-50801 manufactured by Kureha Chemical Industry
(Trade name) was classified, and finely divided activated carbon having an average particle size of 80 microns was used. A catalyst was prepared in the same manner as in Example 1 and used under the same conditions.

 However, the feedstock composition ratio was changed as follows.

Carbon monoxide: methanol: methyl iodide = 530: 90: 10 The results of this experiment are shown in the table below.

The reaction conditions COMPARATIVE EXAMPLE EXAMPLES H ₂ / CO (molar ratio) 0/530 150/530 methanol reaction ratio (%) 88.0 100.0 product composition (methanol-based mole%) acetic acid 31.0 91.0 methyl acetate 50.0 3.5 dimethyl ether 5.1 0 methane 1.5 5.0 carbon dioxide 2.40 Example 3 The same catalyst as in Example 1 was used under the same conditions,
The raw material supply composition was classified into the following two types.

(1) Carbon monoxide: methanol: methyl iodide = 500: 95: 5 (2) Carbon monoxide: methanol: methyl iodide = 500: 97.
5: 2.5 The results of Example 3 are shown in FIG.

As shown in FIG. 1, when the methyl iodide concentration is low,
The catalytic activity increases temporarily at the start of hydrogen introduction, but then decreases fairly rapidly.

It can be seen from FIG. 1 that a high methyl iodide partial pressure of the feed stream is required to maintain the iodine / nickel ratio adjusted by the pretreatment.

〔The invention's effect〕

First, as is clear from the above-mentioned Examples and Comparative Examples, by using a metallic nickel catalyst supported on a carbonaceous carrier and a co-catalyst, and by allowing hydrogen to be present in the reaction system, total acetic acid and methyl acetate were collected. As the rate increases, the catalytic activity improves and the yield of acetic acid improves.

Second, the condensable products present in the reaction system, that is, acetic acid, methyl acetate, water, etc., and unreacted products of gas, such as carbon monoxide, hydrogen, and methane, are easily separated and Gaseous substances such as carbon oxide and hydrogen can be easily returned to the reaction zone under high pressure. Therefore, the utilization rate of carbon monoxide can be easily increased.

Thirdly, a hydrogen-containing low-purity source gas can be used to allow hydrogen to be present in the reaction system. Since the hydrogen partial pressure in the reaction system can be increased, it is possible to directly separate and remove hydrogen from the return flow to the reaction zone, and it is also easy to control to the optimum hydrogen partial pressure.

Fourth, the methanol conversion rate is easily 100%
Therefore, the circulating flow of methanol, methyl acetate, etc. in the reaction system is reduced, and the purification process of the product can be simplified.

Fifth, under the reaction conditions of the method of the present invention, since the amount of water present in the reaction system is small and the water content in the crude product is very small,
The capacity of the dehydrator in the refining process is reduced and the utility is also reduced.

Sixth, since the method of the present invention is based on a gas phase reaction, even if a by-product is produced, its separation is easy and the treatment after separation is also easy. Further, the problem of corrosion of the device does not occur.

[Brief description of drawings]

 FIG. 1 is a graph showing the results of Example 3.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location // B01J 23/755 C07B 61/00 300 C07B 61/00 300 B01J 23/74 321X (56) Reference References JP-A-59-20236 (JP, A) JP-A-59-139330 (JP, A) JP-A-60-36438 (JP, A) JP-A-56-104839 (JP, A)

Claims (1)

(57) [Claims] 1. Methanol and carbon monoxide are mixed at 0.1 to 30 MPa.
To produce acetic acid and methyl acetate by gas phase reaction in the presence of a catalyst composed of metallic nickel supported on a carbonaceous support and a cocatalyst composed of a volatile halogen compound at a pressure of 373 to 673 K and a temperature of 373 to 673 K. The method for producing acetic acid and methyl acetate is characterized in that the reaction is carried out in the presence of hydrogen at 1 to 40 mol% of carbon monoxide.