JPS5822449B2 - Production method of alkylene glycol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing alkylene glycol by the hydration reaction of alkylene oxide, and more specifically, the hydration reaction of alkylene oxide is carried out as a catalyst in an alkali metal halide in the coexistence of alkylene carbonate. The method of producing alkylene glycol by the hydration reaction of 6-alkylene oxide is well known, and generally alkylene oxide is reacted with a large amount of water in the presence or absence of a catalyst to produce an alkylene glycol of 100-200%
A method of carrying out an aqueous phase reaction at a temperature of °C has been used.

In this method, unless a large amount of water is present in the reaction system, dialkylene glycol, trialkylene glycol, and other by-products are produced significantly.
Since the yield of alkylene glycol is low and impractical, for example, in the case of producing ethylene glycol from ethylene oxide, 1 mole of ethylene oxide
The reaction is carried out in the presence of a large excess of water, such as 0 to 15 mol, or in the case of producing propylene glycol from propylene oxide, 15 to 20 mol per mol of propylene oxide.

However, even if such a large amount of water is used, relatively large amounts of by-products such as diglycol and triglycol are unavoidable, and since a large amount of water is used, the reaction products are naturally quite dilute. Therefore, the separation and purification of the reaction product after the reaction is completed requires the consumption of correspondingly large amounts of equipment and energy.

As a way to overcome the difficulties in conventional methods,
Recently, a method has been proposed for producing alkylene glycol by reacting alkylene oxide with water and carbon dioxide using a specific catalyst (Japanese Patent Publication No. 49-24448
, Japanese Unexamined Patent Application Publication No. 51-127010, Japanese Unexamined Patent Publication No. 54-19905, etc.)
.

According to these methods, water is used in a nearly stoichiometric amount relative to alkylene oxide, and the desired product (monocarbons) can be obtained with high yield without producing large amounts of by-products such as diglycol and triglycol. ) alkylene glycol was obtained, and it has been shown that the drawbacks of the above-mentioned conventional methods can be largely improved.

However, when these methods are carried out industrially, it is necessary to install equipment that can supply a large amount of carbon dioxide near the alkylene glycol manufacturing equipment, for example,
In plants that produce propylene oxide by the chlorohydrin method and propylene glycol by its hydration, it is not necessarily easy to improve existing facilities using the above method if there is no carbon dioxide supply facility nearby. As a result of various studies, the inventors added alkylene carbonate to the reaction system from the beginning of the reaction,
When alkylene oxide is reacted in aqueous phase in the presence of a catalyst, the amount of water required for the reaction can be reduced to almost the stoichiometric amount without supplying carbon dioxide. High yields can be obtained with very little by-products such as triglycol, and since the reaction system does not contain a large amount of gas phase, the reaction is smooth and operation is easy. It has now been found that the target alkylene glycols can be advantageously prepared.

That is, the present invention aims to provide a method for producing alkylene glycol, which is characterized by carrying out an aqueous phase reaction of alkylene oxide using an alkali metal halide as a catalyst in the coexistence of alkylene carbonate.

The method of the present invention will be explained in more detail below.

The alkali metal halides used as catalysts in the process of the invention are preferably eg sodium chloride (
Salt), thorium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, etc. are themselves non-volatile and stable inorganic salts that are economically inexpensive, odorless, and have high catalytic activity. , it can be said that it is practical.

However, it is not necessarily limited to these.

The amount of the catalyst used is at least 0.005 mol %, preferably at least 0.005 mol %, based on the raw material alkylene oxide.
05 mol%, and the reaction is accelerated as the amount increases.

However, as a matter of course, there is a limit to the effect that the catalyst can bring, and even if it is used in too large an amount, it will not necessarily be possible to obtain an effect proportional to the amount.

Therefore, in practice, it is used in a saturation amount of 0.005 mol % to the reaction solution, preferably 0.005 mol % to 10 mol %, most preferably 0.1 to 1.0 mol %.

In particular, ethylene oxide, propylene oxide, and butylene oxide are used as the raw material alkylene oxide.

The amount of water relative to the raw material oxide is stoichiometric (molar ratio 1
．． 0) is sufficient, and depending on the reaction format, it may be possible to carry out the reaction at a lower amount, but from a practical standpoint, it is preferable to carry out the reaction at a slightly excess to about 2.5 times the stoichiometric amount.

The amount of alkylene carbonate to be added to the reaction system from the beginning of the reaction is at least 0.001 mol, preferably at least 0.01 mol, per 1 mol of raw material alkylene oxide, and the more it is, the more effective it is.

However, usually a sufficient effect can be obtained with about 0.05 to 0.20 mol.

The reaction temperature varies depending on the type of raw material oxide, the type of catalyst, the composition of the reaction liquid at the beginning of the reaction, etc., and cannot be uniformly prescribed, but it is generally 40 to 180°C, preferably 100 to 150°C.
It is carried out in the range of 0°C.

The reaction is carried out at the naturally occurring pressure of the reaction system, which is usually maintained under liquid phase conditions, and no special pressurization or depressurization is required.

However, there is no problem in adjusting the pressure inside the reactor as necessary.

Although the reaction of the present invention is carried out under liquid phase conditions, there are no particular restrictions on the reaction mode.

Example 1 46.5P of propylene oxide, 19.1' of water, 20.4S' of propylene carbonate, and 1.8 g of I-lium iodide were placed in an autoclave with an internal volume of 300 m1, and nitrogen gas was pressurized to 10 kg/ciG. After that, the mixture was heated in an electric furnace and reacted at 120°C for 2 hours with stirring.

The liquid obtained after the reaction was clear and colorless, and the analysis results were as follows.

Incidentally, it was observed that almost all of the amounts of propylene carbonate and sodium iodide added at the beginning of the reaction remained as they were.

Example 2 35.2 g of ethylene oxide and 19.8 L of water were placed in an autoclave with an internal volume of 100 m1. , 17.6 P of ethylene carbonate and 1°99 g of potassium iodide were charged,
After pressurizing nitrogen gas to 10 kg/caG, it was heated in an electric furnace and reacted at 120° C. for 2 hours with stirring.

The liquid obtained after the reaction was clear and colorless, and the analysis results were as follows.

Incidentally, it was found that almost all of the amounts of ethylene carbonate and potassium iodide added at the beginning of the reaction remained as they were.

Example 3 In an autoclave with an internal volume of 100 m1, 19.8 g of ethylene oxide, 19.8 S' of water, and 1 ethylene carbonate were added.
-1,7,6P and 0.71' of sodium chloride were charged, nitrogen gas was injected until the pressure reached 10 kg/c77 fG, and the mixture was heated in an electric furnace and reacted at 120° C. for 2 hours with stirring.

The liquid obtained after the reaction was transparent and colorless, and the analysis results were as follows.

It was found that almost all of the amounts of ethylene carbonate and sodium chloride added at the beginning of the reaction remained as they were.

Example 4 In an autoclave with an internal volume of 100 m1, 35.2 fI of ethylene oxide and 19.1 fI of water were placed. ethylene carbonate 1
7.1' and 1.81 g of sodium bromide were charged, nitrogen gas was pressurized until the ratio was 10 to 9/cwtG, and the mixture was heated in an electric furnace and reacted at 120° C. for 2 hours with stirring.

The liquid obtained after the reaction is clear and colorless. The results of the analysis were as described above.

Incidentally, it was found that almost all of the amounts of ethylene carbonate and sodium bromide added at the beginning of the reaction remained as they were.

Example 5 35.2 f of ethylene oxide, 19.8 P of water, and 1 liter of ethylene carbonate were placed in an autoclave with an internal volume of 100 m1.
7.6'? After charging 1.04 f of lithium bromide and pressurizing nitrogen gas to 10 kg/c77 fG, the reactor was heated in an electric furnace and reacted at 120'C for 2 hours with stirring.

The liquid obtained after the reaction was clear and colorless, and the analysis results were as follows.

Incidentally, it was found that almost all of the amounts of ethylene carbonate and lithium bromide added at the beginning of the reaction remained as they were.

Example 6 Ethylene oxide 35.2P and water 19.8P were placed in an autoclave with an internal volume of 100ml. , 4.4P of ethylene carbonate and 1.99P of potassium iodide were charged,
After pressurizing nitrogen gas to 10 kg/caG, it was heated in an electric furnace and reacted at 120° C. for 2 hours with stirring.

The liquid obtained after the reaction was clear and colorless, and the analysis results were as follows.

Incidentally, it was found that almost all of the amounts of ethylene carbonate and potassium iodide added at the beginning of the reaction remained as they were.

Example 7 In an autoclave with an internal volume of 100 m1, 352 g of ethylene oxide, 19.8 g of water, and 17 g of ethylene carbonate were placed.
．． After charging 6P and 1.02 kg of potassium iodide and pressurizing nitrogen gas to 10 kg/crAG, the reactor was heated in an electric furnace and reacted at 120°C for 2 cycles with stirring.

The liquid obtained after completion of the reaction was colorless and transparent, and the analysis results were as follows.

Incidentally, it was found that almost all of the amounts of ethylene carbonate and potassium iodide added at the beginning of the reaction remained as they were.

Example 8 35.2 f of ethylene oxide and 27 f of water in an autoclave with an internal volume of 100 m1? , ethylene carbonate 17
．． After charging 6P and 1.91' of potassium iodide and pressurizing nitrogen gas to 10 kg/crA, it was heated in an electric furnace and reacted at 150°C for 2 hours with stirring.

The liquid obtained after the reaction was clear and colorless, and the analysis results were as follows.

Incidentally, it was found that almost all of the amounts of ethylene carbonate and potassium iodide added at the beginning of the reaction remained as they were.

Example 9 Ethylene oxide 35.2 cm in an autoclave with an internal volume of 100 m1. , water 19.8 g, ethylene carbonate 1
7.6f? and potassium fluoride 0.70 f? After charging and pressurizing nitrogen gas to 10 kg/crAG,
The mixture was heated in an electric furnace and reacted at 120° C. for 2 hours with stirring.

The liquid obtained after the reaction was clear and colorless, and the analysis results were as follows.

Incidentally, it was found that almost all of the amounts of ethylene carbonate and potassium fluoride added at the beginning of the reaction remained as they were.

Comparative Example 1 Example 1 without adding propylene carbonate
When the reaction was carried out in the same manner as above, the reaction solution obtained was colorless and transparent, and the analysis results were as follows.

Comparative Example 2 A reaction was carried out in the same manner as in Example 2 except that potassium iodide was not added. The reaction solution obtained was colorless and transparent, and the analysis results were as follows.

Claims (1)

[Claims] 1. A method for producing alkylene glycol, which comprises subjecting alkylene oxide to a water-use reaction using an alkali metal halide as a catalyst in the coexistence of alkylene carbonate.