JPH0249743A - Production of allyl alcohol - Google Patents

Abstract

PURPOSE:To advantageously produce allyl alcohol stably for a long period by hydrolyzing allyl acetate using a cation exchange resin having a crosslinking degree and moisture content within specific ranges. CONSTITUTION:Allyl acetate and water are subjected to hydrolytic reaction in the liquid phase in the presence of a cation exchange resin having >=55%, preferably >=65% moisture content and >=6%, preferably >=4% crosslinking degree to afford allyl alcohol. The unreacted allyl acetate is preferably used as a circulating liquid to the hydrolytic step and acetic acid is preferably circulated to synthetic reaction of the allyl acetate for use.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing allyl alcohol. More specifically, the present invention relates to an improvement in a method of hydrolyzing allyl acetate by contacting it with a cation exchange resin during the process of hydrolyzing allyl acetate to produce allyl alcohol.

[Problems to be Solved by the Invention] Various methods are known for producing allyl alcohol, one of which is to hydrolyze allyl acetate produced by reacting propylene, oxygen, and acetic acid. It is known that this is industrially advantageous. The reaction is a reversible reaction carried out by equation (1), and the equilibrium constant shown by equation (2) is as small as 0.39.

CHCOOC3H5+H20 =; C3H,, OH+CH3CO0H...
(1) Equilibrium constant (2) A cation exchange resin is usually used as a catalyst to advantageously promote this hydrolysis, but chemically the equilibrium constant decreases over time, and physically the cation exchange resin Due to equipment problems caused by swelling of the resin, allyl alcohol cannot be obtained stably for a long period of time, and the resin must be replaced frequently.

The present inventors focused on this problem and conducted intensive studies to improve the lifespan of cation exchange resins, and found that by using cation exchange resins with a degree of crosslinking and water content within a specific range. It was discovered that long-term stable operation is possible.

[Means for Solving the Problems] The present inventors have intensively studied a method for industrially advantageously producing allyl alcohol, particularly a process for obtaining allyl alcohol by hydrolyzing allyl acetate. It was discovered that an ion exchange resin having a water content of 55% or more and a degree of crosslinking of 6% or less is suitable for long-term stable operation, and the present invention was achieved. The type of resin to be used may be either a gel type or a porous type; the porous type is better in terms of longevity and less decline in catalytic activity, but it is more expensive than the gel type, so considering economic efficiency, All you have to do is choose one.

It is known that the factors that shorten the catalyst life of conventional allyl acetate hydrolysis include easily polymerizable low-boiling components such as acrolein in the hydrolysis feed solution and high-boiling components such as allylidene diacetate that produce acrolein upon hydrolysis. Many attempts have been made to remove these catalyst-adverse substances from the hydrolysis feed solution in advance. However, the low boiling point components and high boiling point components, which are side reaction products, are in trace amounts, and it requires a large amount of energy to remove them in advance. This method is disadvantageous in terms of process and energy, as acetic acid, which is a high-boiling point component, is produced, forcing removal of the high-boiling point component again.

As a result of investigating a method for stably performing hydrolysis over a long period of time without suffering from these adverse effects, we found that not only the degree of crosslinking of cation exchange resins, which had been previously pointed out, but also the water content have a large effect on the catalyst life of the resin. This is what I discovered.

That is, as a criterion for selecting a resin to be used for this hydrolysis from commercially available cation exchange resins with a degree of crosslinking of 2 to 16% and a water content of 25 to 85%, first of all, the water content is closely related to the swelling of the resin. , the higher the water content, the less swelling there is, and the equipment can be used stably for a long time.
5% or more, preferably 60% or more, more preferably 65%
It is preferable to use a resin having a moisture content of at least 10%.

Further, the degree of crosslinking has a great effect on the hydrolysis reaction rate, and the lower the degree of crosslinking, the higher the reaction rate, and the less decrease in reaction rate due to changes over time, allowing stable operation over a long period of time as a process. Specifically, a resin having a degree of crosslinking of 6% or less, preferably 4% or less is suitable, but due to problems with the strength of the resin, the lower limit is about 2%.

The present invention will be specifically explained below.

First, propylene, oxygen, and acetic acid are reacted in the gas phase in the presence of a synthesis catalyst to obtain allyl acetate. Subsequently, the reaction gas is cooled and separated into a condensed component consisting essentially of allyl acetate, acetic acid, and water, and a non-condensable component consisting of propylene, CO3, and oxygen.

The condensed component is mixed with a circulating liquid containing allyl acetate as a main component, which is separated in the allyl alcohol purification step after hydrolysis, and introduced into the hydrolysis tower. In the hydrolysis tower, allyl acetate and water undergo a hydrolysis reaction in the liquid phase in the presence of a cation exchange resin to produce allyl alcohol and acetic acid. Although the form of the hydrolysis tower feed liquid may be a heterogeneous phase, it is desirable to have a homogeneous phase as much as possible from the viewpoint of reaction stability and long catalyst life, and if necessary, acetic acid to be separated in the next step is mixed by circulation. This hydrolysis reaction is an equilibrium reaction, and water may be added to the feed liquid to advantageously guide the reaction.

There is no particular restriction on the reaction temperature, but if it is too low, the catalyst activity will be insufficient, and if it is too high, it will cause deterioration of the resin.
Usually 50 to 130°C, preferably 60 to 100°C is selected. The time required for the reaction varies depending on the reaction temperature and the composition of the feed solution, but it is usually sufficient if it is selected from the range of several minutes to several hours.

Subsequently, the hydrolyzed reaction liquid, which essentially consists of allyl alcohol, allyl acetate, acetic acid, and water, is separated into each component by distillation or other separation operations, and allyl alcohol is extracted as a product, and allyl acetate is hydrolyzed. Acetic acid is recycled to the allyl acetate synthesis reaction as a circulating liquid to the column.

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

Note that the present invention is not limited to these Examples.

[Example 1] The main components are a condensate obtained by cooling the reaction gas obtained by reacting propylene, oxygen, and acetic acid, and allyl acetate from the step of hydrolyzing the condensate to purify allyl alcohol. Allyl acetate 25.2%, water 31% as circulating fluid mixture
．． 1%, allyl alcohol 2.4%, acetic acid 34.4%,
A liquid containing 6.9% was obtained.

A hydrolysis reaction was carried out by flowing 50 cc/II of this solution into a glass jacketed chromatography tube filled with 20 cc of cation exchange resin. The reaction temperature was maintained at 80° C. by flowing hot water through the outer tube. Degree of crosslinking as cation exchange resin: 4
%, and a porous resin with a water content of 78% was used.

Table 1 shows changes in reaction time, hydrolysis reaction equilibrium constant, and resin swelling ratio.

There was little swelling, and the equilibrium constant remained constant and at a high level for a long period of time.

The swelling ratio is defined as:

[Example 2] A hydrolysis reaction was carried out in the same manner as in Example 1, except that a porous resin having a degree of crosslinking of 4% and a water content of 68% was used as the cation exchange resin.

Table 1 shows changes in reaction time, hydrolysis reaction equilibrium constant, and resin swelling ratio.

There was little swelling, and the equilibrium constant remained constant and at a high level for a long time.

[Example 3] A hydrolysis reaction was carried out in the same manner as in Example 1, except that a porous resin with a degree of crosslinking of 6% and a water content of 65% was used as the cation exchange resin.

Table 1 shows changes in reaction time, hydrolysis reaction equilibrium constant, and resin swelling ratio.

The equilibrium constant also remained constant and at a high level for a long period of time.

Although the swelling of the resin is larger than that in Example 2, it is within a range that can be used in actual equipment.

[Example 4] A hydrolysis reaction was carried out in the same manner as in Example 1, except that a gel type resin with a degree of crosslinking of 6% and a water content of 63% was used as the cation exchange resin.

Table 1 shows changes in reaction time, hydrolysis reaction equilibrium constant, and resin swelling ratio.

The decrease in the equilibrium constant is slightly larger than that of the porous type. Although the swelling of the resin is larger than that in Example 2, it is within a range that can be used in actual equipment.

[Example 5] A hydrolysis reaction was carried out in the same manner as in Example 1, except that a porous resin having a degree of crosslinking of 6% and a water content of 55% was used as the cation exchange resin.

Table 1 shows changes in reaction time, hydrolysis reaction equilibrium constant, and resin swelling ratio.

The equilibrium constant also remained constant and at a high level for a long period of time, but the swelling of the resin was larger than the others and was judged to be the upper limit that can be used in actual equipment.

[Comparative Example 1] A hydrolysis reaction was carried out in the same manner as in Example 1, except that a porous resin having a degree of crosslinking of 14% and a water content of 64% was used as the cation exchange resin.

Table 1 shows changes in reaction time, hydrolysis reaction equilibrium constant, and resin swelling ratio.

Although the swelling of the resin is comparable to that of Examples 3 and 4, it is judged that the resin can be used, but the equilibrium constant is lower than the initial value and the decrease over time is large, making it unsuitable for use in actual equipment.

(The following is a blank space) [Effects of the Invention] By using the cation exchange resin of the present invention, it has become possible to stably produce allyl alcohol by hydrolyzing allyl acetate for a long period of time.

Claims (1)

[Claims] A method for producing allyl alcohol, which comprises using a cation exchange resin having a water content of 55% or more and a degree of crosslinking of 6% or less when producing allyl alcohol by hydrolyzing allyl acetate.