JPS5823369B2 - Method for producing alkylene glycol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing alkylene glycol by a hydration reaction of alkylene oxide, and more specifically, a method characterized by carrying out a hydration reaction of alkylene oxide using an ammonium salt as a catalyst in the coexistence of alkylene carbonate. Regarding.

The method of producing alkylene glycol by the hydration reaction of alkylene oxide is well known, and generally involves hydrating alkylene oxide with a large amount of water at a temperature of 100 to 200°C in the presence or absence of a catalyst. method is being done.

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,
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 large. It is obtained as a dilute aqueous solution, and therefore a large amount of equipment and energy must be consumed to separate and purify the reaction product after the reaction is completed.

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. 49-2444-
8, JP-A No. 51-127010, JP-A No. 54-19905, etc.).

According to these methods, for alkylene oxide,
Using water close to the stoichiometric amount, and without producing large amounts of by-products such as diglycol and triglycol,
It has been shown that the desired (mono)alkylene glycol can be obtained with a high yield, and 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 for producing propylene oxide using the chlorohydrin method and propylene glycol using water, it is not necessarily easy to improve existing facilities using the above method if there is no carbon dioxide supply facility nearby.

Therefore, as a result of various studies, the present inventors have found that when alkylene carbonate is added to the reaction system from the beginning of the reaction and alkylene oxide is subjected to a water-use reaction in the presence of a catalyst, it is possible to do so without supplying carbon dioxide. , the amount of water required for the reaction can be reduced to almost the stoichiometric amount, and the by-products such as diglycol and triglycol are also very small, resulting in high yields. It has been found that since the process does not contain a gas phase, the reaction can be carried out smoothly and operation is easy, making it possible to produce the target alkylene glycol with great industrial advantage.

That is, the present invention provides a method for producing alkylene glycol, which is characterized by carrying out a water-use reaction of alkylene oxide using an ammonium salt as a catalyst in the coexistence of alkylene carbonate.

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

The ammonium salt used as a catalyst in the method of the present invention is represented by the following general formula.

(However, R1, R2, R3 and R4 are each a hydrogen atom, an alkyl group, an alkenyl group or an aryl group,
X represents an iodine atom, a bromine atom or a chlorine atom.

) Some typical examples of ammonium salts used in the method of the present invention include tetramethylammonium iodide, tetramethylammonium bromide, tribenzylmethylammonium chloride, and triiodide.

Examples include methylammonium, diethylammonium bromide, and ammonium chloride.

In order to obtain these, substances which form the desired catalysts may also be added to the reaction mixture, for example a mixture of trimethylamine and methyl iodide forming tetramethylammonium iodide.

The amount of these catalysts 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 a catalyst can bring, and even if it is used in an excessively large amount, an effect proportional to the amount cannot necessarily be obtained.

Therefore, in practice, it is used in a saturation amount of 0.005 mol% to the reaction solution, preferably 0.05 to 10 mol%, optimally 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 °C.

The reaction is carried out at the naturally occurring pressure of the reaction system, which is usually kept 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 46.6 mm of propylene oxide was placed in an autoclave with an internal volume of 1001 rLl. ! l, water 19.8. i7, 20.4 g of propylene carbonate and 3.08 g of tetraethylammonium iodite were charged, and 10 kg/g of nitrogen gas was charged.
After press-fitting until it becomes CrIf, G, it is heated in an electric furnace for 12
The reaction was allowed to proceed at 0° C. for 2 hours with stirring.

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

Propylene oxide conversion rate 98.0% Selectivity: Propylene glycol 98.0% Cyfropylene glycol 2.0% In addition, almost all of the amounts of propylene carbonate and tetraethylammonium iodite added at the beginning of the reaction remain. This was recognized.

Example 2 In an autoclave with an internal volume of 100TLl, 35.2g of ethylene oxide, 19.8g of water, and 17.6j of ethylene carbonate! and 2.45 g of tetramethylammonium iodite, and nitrogen gas was added to 10 to 9/crit.
After press-fitting until it reaches G, heat it in an electric furnace and heat it at 120℃ for 2
The reaction was allowed to take place under stirring for an hour.

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

2 Ethylene oxide conversion rate 98.6% selectivity: ethylene glycol 98.3% diethylene glycol 1.7% In addition, almost all of the amounts of ethylene carbonate and tetramethylammonium iodite added at the beginning of the reaction remain as they are. was recognized.

Example 3 In an autoclave with an internal volume of 100 m1, 35°2 g of ethylene oxide, 19.8 g of water, and 1 part of ethylene carbonate were placed.
7.6.9 and 1.85g of tetramethylammonium bromide, and nitrogen gas was added at 10kg/critG.
After the mixture was press-fitted until it became , 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.

Ethylene oxide conversion rate 99.0% selectivity: ethylene glycol 97.9% diethylene glycol 2.1% It should be noted that almost all of the amounts of ethylene carbonate and tetramethylammonium bromide added at the beginning of the reaction remained as they were. Admitted.

Example 4 In an autoclave with an internal volume of 100 m1, 36.5 g of ethylene oxide, 19.8 g of water, and 1 part of ethylene carbonate were placed.
7.69 and trimethylbenzylammonium chloride 2,23.9, and nitrogen gas at 10Kg/iG.
After the mixture was press-fitted until it became , 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.

Ethylene oxide conversion rate 98.5% Selectivity: Ethylene glycol 96.9% Diethylene glycol 3.1% It was observed that almost all of the amounts of ethylene carbonate and trimethylbenzylammonium chloride that were added at the beginning of the reaction remained as they were. It was done.

Example 5 36.5 g of ethylene oxide, 19.8 g of water, 17.6 g of ethylene carbonate, and 2.24 g of trimethylammonium iodite were charged into an autoclave with an internal volume of 10,011 Ll, and nitrogen gas was pressurized until the pressure reached 10y/ff1G. The mixture was heated in a 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.

Ethylene oxide conversion rate 98.4% Selectivity: ethylene glycol 98.1% diethylene glycol 1.9% It was observed that almost all of the amounts of ethylene carbonate and trimethylammonium chloride added at the beginning of the reaction remained as they were. Ta.

Example 6 35.2 g of ethylene oxide, 19.8 g of water, 4.4 g of ethylene carbonate, and 2.41 g of tetramethylammonium iodite were charged into an autoclave with an internal volume of 1001 rLl, and nitrogen gas was pressurized until the pressure reached 10 kg/citG. Heat in an electric furnace at 120℃ for 2 hours.
The reaction was carried out under stirring.

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

Ethylene oxide conversion rate 98.2% Selectivity: Ethylene glycol 93.1% Diethylene glycol 6.9% It should be noted that almost all of the amounts of ethylene carbonate and tetramethylammonium iodite added at the beginning of the reaction remained as they were. Admitted.

Example 7 In an autoclave with an internal volume of 100 m1, 35.2 g of ethylene oxide, 19.8 g of water, and 1 part of ethylene carbonate were placed.
7.6g and 1 tetramethylammonium iodite
．． After charging 21 g of nitrogen gas and pressurizing it until the concentration was 10 Kg/crItG, 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.

Ethylene oxide conversion rate 98.0% Selectivity: Ethylene glycol 92.2% Diethylene glycol 7.8% It should be noted that almost all of the amounts of ethylene carbonate and tetramethylammonium iodite added at the beginning of the reaction remained as they were. was recognized.

Example 8 In an autoclave with an internal volume of 1007111, 35.2 g of ethylene oxide, 27 g of water, and ethylene carbonate I-
17.6 g and 2.41 g of tetramethylammonium iodite were fed with nitrogen gas at 10 Kg/crit.
After press-fitting until it reached G, 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.

Ethylene oxide conversion rate 99.6% selectivity: ethylene glycol 95.3% diethylene glycol 4.7% It should be noted that almost all of the amounts of ethylene carbonate and tetramethylammonium iodite added at the beginning of the reaction remained as they were. Admitted.

Example 9 In an autoclave with an internal volume of 100 m1, 35.2 g of ethylene oxide, 19.8 g of water, and 1 part of ethylene carbonate were placed.
7.6g, trimethylamine 0.719 and methyl iodide L709 were charged, and nitrogen gas was added at 10kg/ff1G.
After press-fitting until
The reaction was allowed to take place under stirring for an hour.

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

Ethylene oxide conversion rate 98.5% Selectivity: ethylene glycol 98.1% diethylene glycol 1.9% It was observed that almost the entire amount of ethylene carbonate added at the beginning of the reaction remained as is.

Comparative Example 1 All the same as Example 1 except that propylene carbonate was not added.
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.

Propylene oxide conversion rate 80.0% Selectivity: Propylene glycol 33.5% Cyfropylene glycol 37.0% Tripropylene glycol/L/ 16.2% Other low boiling substances 13.3 Comparative example 2 Tetramethylammonium iodine The reaction was carried out in the same manner as in Example 2, except that the additive was not added. The reaction solution obtained was colorless and transparent, and the analysis results were as follows.

Ethylene oxide conversion rate 21.6% Selectivity: Ethylene glycol 61.2% Diethylene glycol 28.3% Triethylene glycol 4.5%

Claims (1)

[Claims] 1. A method for producing alkylene glycol, which comprises hydrating alkylene oxide using an ammonium salt as a catalyst in the coexistence of alkylene carbonate.