JPS6033417B2 - Method for producing acetate ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing acetic acid ester by reacting acetic acid with an aliphatic lower olefin in a gas phase, and particularly to a method for producing ethyl acetate from acetic acid and ethylene.

The method for producing the corresponding carboxylic acid ester from an olefin and a carboxylic acid is broadly divided into a gas phase method and a liquid phase method based on the reaction mode. The gas phase method can be said to have great advantages in that there is no recovery burden and no complicated operations are required to separate the target product from the reaction solution. Conventionally, many reports have been made regarding catalysts for carrying out such gas phase methods, including sulfuric acid, ethyl sulfuric acid, and jetyl sulfuric acid.

Among these, aromatic disulfonic acid silica catalysts such as benzenedisulfonic acid described in Samurai Sekisho 50-46 Ida No. 7 are considered to be useful as they cause relatively little corrosion of the equipment, and the present inventors et al. conducted a study focusing on this catalyst, and found that it is a catalyst that is expected to be put into practical use as it exhibits less activity decline than sulfuric acid catalysts and provides a high space-time yield (STY). did. However, according to the findings of the present inventors, when using this catalyst, carboxylic acid esters are obtained with high activity and high space-time yield in the early stage of the reaction, but as the reaction progresses, the catalyst activity decreases and the space-time yield of the carboxylic acid esters gradually decreases. It was found that this method was disadvantageous when producing carboxylic acid esters on an industrial basis because the yield was reduced.

However, the inventors of the present invention have conducted extensive research in order to find a method for producing carboxylic acid esters with good yield over a long period of time while preventing such a decrease in the activity of the catalyst. The inventors have discovered that this object can be achieved when acetic acid and aliphatic lower olefin are reacted in the gas phase on a solid catalyst supporting aromatic disulfonic acid and/or its ester, and have completed the present invention. .

The feature of the present invention is that the silica carrier is treated with a strong acid in advance to prevent the activity of the catalyst from decreasing over time.
Examples of strong acids include inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, and organic acids such as benzene monosulfonic acid, benzene disulfonic acid, naphthalene disulfonic acid, and naphthalene trisulfonic acid.

Treatment with strong acid involves adding silica to the acid,
Any method can be used, such as filling a tube or cylinder with silica and injecting strong acid from the top, but usually the silica is immersed in the strong acid and heated at about 100 to 200°C for 5 to 2 times. Thereafter, it is cooled, thoroughly washed with water, and then heated and dried under reduced pressure and then under increased pressure. A practical silica carrier has a specific surface area of about 100 to 300 meters. An aromatic disulfonic acid catalyst is supported on the silica treated with a strong acid. Aromatic disulfonic acid catalysts used in the present invention include benzene-1,2-disulfonic acid, benzene-1,3-disulfonic acid, benzene-1,4-disulfonic acid, naphthalene-1,5-disulfonic acid, and naphthalene-2,6-disulfonic acid. Acid, naphthalene-2,7-
Examples include disulfonic acid.

Benzene-1,3-disulfonic acid and bufthalene-2,
6-disulfonic acid is particularly effective. Such disulfonic acids may be not only free acids but also esters thereof. It is practical to match the type of ester to the type of olefin used; for example, when ethylene is used as a raw material, ethyl ester of aromatic disulfonic acid is used. The catalyst may be used alone or in combination with acids, esters, a mixture of acids and esters, etc. There is no particular limitation on the pressing method and any method can be used, but usually impregnation method,
That is, a method is carried out in which aromatic disulfonic acid is dissolved in water or acetic acid, the silica is diluted in the solution, and the solvent is distilled off and dried. The supporting ratio of aromatic disulfonic acid is selected from the range of 1.0 to 3.0 meq/catalyst as sulfonic acid groups.

Acetic acid and aliphatic lower olefin are reacted using such a catalyst, and ethylene, propylene, 1-butene, etc. are used as the olefin.

In the present invention, ethyl acetate is preferably produced using ethylene, and isopropyl acetate is produced using propylene. The reaction can be carried out in any manner such as fixed bed or fluidized bed.

The reaction is carried out by continuously or intermittently introducing acetic acid vapor and aliphatic lower olefin into the reactor. At this time, it is of course possible to introduce an inert gas if necessary. The acetic acid concentration of the feedstock is 5-3% by volume, preferably 6%.
~2 cough volume%, molar ratio of lower olefin/acetic acid is ~3
20/1, and the space velocity of the raw material gas is 300 to 5000.
The soot/catalyst/hour is preferably adjusted to 500 to 2000 N/soot/hour. It is also advantageous to add a small amount of water vapor during the reaction because it further prevents the activity of the catalyst from decreasing over time. The supply ratio of steam is 0.3 to 15% by weight relative to the charged acetic acid, preferably 0.5 to 1.
A range of 15% by weight or less is desirable; below 0.3% by weight, the effect of preventing the catalyst's activity from decreasing over time is poor;
If it exceeds this level, the activity of the catalyst itself decreases, which poses a practical problem.

The reaction temperature is 130-200qo, preferably 160-18
The reaction pressure at 0°C is normal pressure to 20 kg'G, preferably 5 to 1
5k9' ground G are appropriate. After cooling and collecting the generated gas leaving the reactor, the target product is isolated by a conventional method such as distillation or extraction.

Next, the method of the present invention will be explained in more detail with reference to implementation. Example 1 13 parts of sulfuric acid, 30 parts of water, and 50 parts of silica were mixed, dried, and then heated at 165°C for one hour.

After cooling, it was thoroughly washed with water and dried at 100°C for 2 hours. Next, a solid catalyst 80' in which benzene-1,3-disulfonic acid was supported on the silica carrier at a ratio of 2 meq/unit catalyst in terms of sulfonic acid groups was placed on Shigeru Uchi's side in a stainless steel carrier with a length of 78 m. Fill the reaction tube, heat it to 165℃, and then add a mixed gas consisting of ethylene, acetic acid vapor, and water vapor under a pressure of 6k9/g from the top of the reaction tube (the acetic acid concentration is 10 volumes based on the total amount of acetic acid and ethylene). %, the amount of water vapor was 2% by weight based on the charged acetic acid) was introduced at a space velocity of 85 plates/1 touch/hour to carry out the reaction.

The produced reaction gas was collected by cooling, and the space-time yield (STY) of the produced ethyl acetate was monitored over time using gas chromatography. As a result, STY was 2 hours from the start of the reaction (S
Up to TY-1) averages 190 ta'ku catalyst/day, Matsu~2
The average time (STY-0) was 164 evenings/one catalyst day and the average time (STY one day) was 153 evenings/day, indicating that high activity was maintained over a long period of time.

Comparative Example When untreated silica was used in Example 1, STY-1 was 177 t/day, STY-ro was 147 t/day, and STY-m was 132 t/day.
The activity of the catalyst decreased significantly.

Examples 2 to 5 Experiments were conducted according to Example 1 under the conditions shown in Table 1. The results are shown in Table 1. Table 1

Claims (1)

[Claims] 1. Reacting acetic acid and an aliphatic lower olefin in the gas phase on a solid catalyst in which an aromatic disulfonic acid and/or its ester is supported on a silica carrier that has been treated with a strong acid and then washed with water. A method for producing an acetate ester, characterized by: 2. The manufacturing method according to claim 1, wherein the aromatic disulfonic acid is benzenesulfonic acid or naphthalene disulfonic acid. 3. The manufacturing method according to claim 1, wherein an olefin having 4 or less carbon atoms is used as the fatty acid olefin.