JPS6017775B2 - 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 and an aliphatic lower olefin in a gas phase method, and particularly relates to a method for producing ethyl acetate from acetic acid and ethylene.

Methods for producing corresponding carboxylic acid esters from olefins and carboxylic acids are broadly divided into gas phase methods and liquid phase methods based on the reaction form, but they do not require harsh conditions such as high temperature and high pressure, and they require the use of solvents. It can be said that the gas phase method has great advantages in that there is no recovery burden, and there is no need for troublesome operations 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 catalysts such as benzenedisulfonic acid described in Tokkokukan Sho 50-46587 are considered to be useful in that they cause relatively little corrosion of equipment, and the present inventors have After considering the following, we found that
It has been found that this catalyst exhibits less decrease in activity than other catalysts such as sulfuric acid, provides a high space-time yield (STY), and is expected to be put to practical use. However, according to the findings of the present inventors, when using this catalyst, carboxylic acid esters are obtained with high activity and a high space-time yield in the early stage of the reaction, but as the reaction progresses, the catalytic activity decreases and the carboxylic acid esters are gradually reduced. It has been found that the space-time yield decreases, which is disadvantageous when producing carboxylic acid esters on an industrial basis.

However, the inventors of the present invention have conducted extensive research in order to find a method for producing carboxylic acid esters over a long period of time and at a high yield while preventing such a decrease in the activity of the catalyst. The present inventors have discovered that this object can be achieved when acetic acid and aliphatic lower olefin are reacted in the gas phase in the presence of water vapor over a solid catalyst, and have completed the present invention.

A feature of the present invention is to prevent the activity of the catalyst from decreasing over time by allowing water vapor to coexist in the system during the reaction between acetic acid and aliphatic lower olefin. It is remarkable only in combination with a specific catalyst called ester.

That is, even when using other known catalysts such as sulfuric acid, the presence of water vapor contributes to preventing a decrease in activity to some extent, but it cannot reach a practical level. Furthermore, depending on the type of catalyst or the amount of water vapor present, the activity of the catalyst may be inhibited, and the aromatic disulfonic acid or ester catalyst of the present application exhibits a unique behavior. Conventionally, when producing acetate ester through a gas phase reaction between acetic acid and olefin, no technology has been attempted to actively coexist water vapor in the system; conversely, the coexistence of water vapor inhibits the reaction. Considering the fact that it has been reported that this is undesirable, the method of the present invention must be said to be a completely unexpected phenomenon based on conventional knowledge. Furthermore, the present invention has the great advantage that corrosion of the equipment, which is said to be a drawback of the gas phase method when a strong acid catalyst is used, is significantly improved. In the present invention, when acetic acid and aliphatic lower olefin are reacted, ethylene, propylene, butenes, etc. are used as the aliphatic lower olefin, and ethyl acetate is produced using ethylene, and isopropyl acetate is produced using propylene. This is preferably carried out in some cases.
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. Examples include disulfonic acid, naphthalene-2,7-disulfonic acid, and the like.

Benzene-1,3-disulfonic acid and naphthalene-2,
6-disulfonic acid is particularly effective. Such disulfonic acids may be not only free acids but also their esters. 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. The catalyst is used by being supported on a suitable solid carrier.

As the carrier, silica is preferably used, and in particular, one having a specific surface area of 100 to 300 mm and an alumina content of 5% by weight or less is advantageous. The supporting method is not particularly limited and any method can be used, but the usual method is an impregnation method, that is, a method in which aromatic disulfonic acid is dissolved in water or acetic acid, silica is soaked in the solution, and the solvent is distilled off and dried. will be held. The carrying rate of aromatic disulfonic acid is 1.0 to 3.0 as a sulfonic acid group.
meq' is selected from a range of catalysts.

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, aliphatic lower olefin and water vapor into the reactor. At this time, it is of course possible to introduce an inert gas if necessary. The concentration of acetic acid in the feedstock is 5-3% by volume, preferably 6-20% by volume, the lower olefin/acetic acid molar ratio is 3-20/1, and the space velocity of the raw material gas is 300% by volume.
~5000N so'〆One touch/hour Preferably 500~2
000N so/so-catalyst/hour, respectively. Further, the supply ratio of steam is desirably in the range of 0.3 to 15% by weight, preferably 0.5 to 10% by weight, based on the acetic acid charged.
．． If the amount is less than 15% by weight, the effect of preventing the catalyst from decreasing in activity over time is poor, while if it is more than 15% by weight, the activity of the catalyst itself decreases, causing a practical problem.

The reaction temperature is 130-200℃, preferably 160-180℃
oo, reaction pressure is normal pressure ~ 20 kg/G, preferably 5 ~
15k9/mass G is suitable for each. 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 by giving examples. Example 1 A solid catalyst, in which benzene-1,3-disulfonic acid was supported on a silica carrier at a ratio of 2 meq' in terms of sulfonic acid groups, was placed in a stainless steel reaction tube with an inner diameter of 22 mm and a length of 780 mm. A mixed gas consisting of ethylene, acetic acid vapor and water vapor (acetic acid concentration is 10% by volume based on the total amount of acetic acid and ethylene, water vapor The reaction was carried out by introducing an amount of 2% by weight based on the charged acetic acid at a space velocity of 85 mm/touch soot/hour.

The reaction collection liquid obtained by cooling and condensing the generated reaction gas was analyzed by gas chromatography, and the space-time yield (STY) of the generated ethyl acetate was monitored over time. As a result, STY averaged 177 evenings/Yuichi catalyst day for 2 hours from the start of the reaction (STY-1), and 147 evenings/Yuichi catalyst day for 22 to 2 hours (STY-B), 46 ~4 report time (STY-
The average of m) was 132 evening/evening-catalyst/day, and high activity was maintained over a long period of time.

Control Examples 1-2 When the use of water vapor was omitted in Example 1, STY
-1 was 185 evening/evening catalyst/day, STY-0 was 88 mu catalyst/day, and STY-m was 55 evening/evening** soot/day, indicating that the activity of the catalyst decreased significantly over time.

Also, in Example 1, a sulfuric acid catalyst was used instead of benzene-1,3-disulfonic acid (however, the reaction pressure was 2k9/G, the reaction temperature was 15600, and the space velocity of the raw material was 800N.
Then, ST
Y-1 is 70 evenings/-catalyst day, STY-ro is 73 evenings/
Evening-catalyst day, STY 1m was 63 evening/evening-catalyst day.

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 * The loading rate for NRIKA is 2meq.

Hornworm soot BDS; benzene-1,3-disulfonic acid BDS
E; benzene-1,3-disulfonic acid jetyl esbul NDS; naphthalene convex 2,6-disulfonic acid example
6 Using the reactor of Example 1 and the same catalyst 80', reaction temperature 14700, under pressure of 2k9/sg, propylene 6/day, acetic acid 29'/day and water 0.46
The reaction was carried out by supplying raw materials in the evening/day ratio.

Claims (1)

[Scope of Claims] 1. An acetic acid ester characterized by reacting acetic acid and an aliphatic lower olefin in the gas phase in the presence of water vapor on a solid catalyst supporting an aromatic disulfonic acid and/or its ester. manufacturing method. 2. The manufacturing method according to claim 1, wherein the aromatic disulfonic acid is benzenedisulfonic acid or naphthalenedisulfonic acid. 3 The ratio of water vapor supplied to the charged acetic acid is 0.5 to 1.
The manufacturing method according to claim 1, wherein the content is 5% by weight. 4. The manufacturing method according to claim 1, wherein an olefin having 4 or less carbon atoms is used as the aliphatic lower olefin.