JPS6056141B2 - 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 reacting alkylene oxide and water.

Specifically, the present invention relates to a method for producing alkylene glycol by reacting alkylene oxide and water in the presence of carbon dioxide using a halogen-type anion exchanger as a catalyst. Alkylene glycols such as ethylene glycol and propylene glycol are used in a wide range of applications as raw materials for polyesters, polyethers, antifreezes, surfactants, and the like.

Conventionally, methods for producing alkylene glycol by reacting alkylene oxide and water include a method using a catalyst such as sulfuric acid (US Pat. No. 2,255,411) and a method in which the reaction is carried out at high temperature and high pressure without using a catalyst. have been adopted on an industrial scale.

These methods inevitably produce by-products of large amounts of dialkylene glycols, tolyls, and polyalkylene glycols in addition to monoalkylene glycols. However, among alkylene glycols, dialkylene glycols, trialkylene glycols, tetraalkylene glycols, and polyalkylene glycols generally have fewer uses than monoalkylene glycols. Therefore, when producing alkylene chlorine from alkylene oxide and water, it is desired to develop a method for producing alkylene glycol that can increase the proportion of monoalkylene glycol produced. Therefore, since the production ratio of alkylene glycols obtained by the reaction of alkylene oxide and water is determined by the molar ratio of water to alkylene oxide, it is necessary to increase the production ratio of monoalkylene glycol in the composition of alkylene glycols. To achieve this, the molar ratio of water to alkylene oxide must be increased. Generally, the raw material is heated at a pressure of 5 to 25 to 9/c#fG and at a temperature of 16 to 200 °C in the presence or absence of a catalyst using a large excess of water of 10 to 30 times the mole relative to the alkylene oxide. A method has been adopted in which the reaction is completed by converting alkylene oxide to alkylene glycol. However, the product obtained by reacting water in large excess with respect to alkylene oxide is a dilute alkylene glycol aqueous solution with a concentration of 5 to 1%. In order to separate and purify alkylene glycol from this dilute aqueous solution, it is necessary to remove a large excess of water, which has the drawback of requiring complicated equipment such as an evaporator and a large amount of energy. Recently, in a method for producing alkylene glycol from alkylene oxide and water, the amount of water relative to alkylene oxide is reduced to about 1 to 5 times the stoichiometric amount in the reaction, and the proportion of monoalkylene glycol produced is increased. Several methods are provided.

For example, in Japanese Patent Publication No. 49-24448, the pressure 1
A method of hydration reaction of alkylene oxide using an alkali metal halide or quaternary ammonium salt as a catalyst in the presence of carbon dioxide at a leakage pressure of 0 to 8 and a temperature of 80 to 220°C, JP-A-1983-1999- 1270W describes a method for producing alkylene glycol by reacting the corresponding alkylene oxide with water and carbon dioxide in an organic base such as triethylamine or pyridine, and JP-A-Sho?
19905 discloses a method of hydrating alkylene oxide in the coexistence of carbon dioxide using a quaternary phosphonium salt as a catalyst. However, the catalytic action of these methods is still insufficient, and there are still points to be improved. Therefore, an object of the present invention is to provide a novel method for producing alkylene glycol.

Another object of the present invention is to obtain an alkylene oxide which is completely simple and chemically capable of producing an alkylene oxide, especially a monoalkylene glycol, with a high selectivity at a low reaction temperature. An object of the present invention is to provide a method for producing glycol. These objects are achieved by a method for producing alkylene glycol, which is characterized in that alkylene oxide and water are reacted in the presence of carbon dioxide using a halogen-type anion exchanger as a catalyst. The alkylene oxide used in the method of the present invention is mainly represented by the general formula (1) (wherein, Rl
, R2, R3 and R4 are hydrogen atoms, carbon atoms 1 to 3
represents an alkyl group having 6 carbon atoms, an aryl group having 6 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, or a cycloalkyl group having 3 to 6 carbon atoms.

), typical examples are ethylene oxide, propylene oxide, isobutylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, bentylene oxide, styrene oxide, etc.
Preferred are ethylene oxide and propylene oxide. As the alkylene oxide as a reaction raw material, alkylene oxide obtained by any method can be used.

For example, raw material ethylene oxide can be obtained by a catalytic oxidation method in which ethylene is reacted with a molecular oxygen-containing gas such as air, oxygen-enriched air, pure oxygen, etc. in the gas phase over a catalyst mainly composed of silver. ethylene oxide can be used. In particular, ethylene oxide purified to substantially 100% is preferred, but impure ethylene oxide and ethylene oxide aqueous solutions obtained before the ethylene oxide purification step can also be used. The general formula (■) corresponds to the alkylene oxide used (wherein, Rl, R2, R3 and R are the same as in the above general formula 1).

) are mainly obtained, typical examples of which are ethylene glycol, 1,2-propylene glycol, isobutylene glycol, and 1,2-propylene glycol.
-butylene glycol, 2,3-butylene glycol,
Bentilene glycol, styrene glycol, styrene glycol, etc. Any water can be used as the reaction raw material, and in particular, fresh water, ion-exchanged water, condensed water of steam, condensed water from the dehydration process in alkylene oxide and alkylene glycol production equipment, etc. can be used.

The amount of water relative to alkylene oxide can be about 1 to 30 times the amount by mole. The anion exchanger used as a catalyst in the present invention is a general anion exchanger having an anion exchange function such as a commercially available organic anion exchange resin, but is made of anion exchangers such as chlorine, bromine, and iodine. In particular, basic anion exchange resins can be mentioned.

Specifically, a halogen type anion exchange resin (trade name: DOwexMSA-1, manufactured by The Tau Co., Ltd.) is preferable. In the catalyst according to the present invention, the exchange capacity of the halogen-type anion exchanger is 0.001 mol% or more, preferably 0.01 to 20 mol%, more preferably 0.1 to 10 mol%, based on the alkylene oxide. It is.

In the present invention, carbon dioxide is alkylene oxide 1
It is used in an amount of 0.00001 to 1 mol, preferably 0.0001 to 1 mol, based on the conditions of the present invention.

Carbon dioxide can usually be added in gaseous form. The reaction temperature varies depending on the type of catalyst, the composition of the reaction liquid at the beginning of the reaction, etc., but is usually 20 to 250°C, preferably 50 to 20°C.
0°C, most preferably 80-200°C. The reaction pressure is 0-30k so that the alkylene oxide remains in the liquid phase.
g/C7l! G is preferably in the range of 2 to 25 kg/C7llG. Of course, there is no particular problem in adjusting the pressure within the reactor as necessary. The reaction format in the present invention can be any of a batch type, semi-batch type and continuous type. As described above, according to the present invention, alkylene oxide and water are reacted at a molar ratio close to stoichiometric amount in the presence of carbon dioxide using a halogen-type anion exchanger as a catalyst. By-products such as alkylene glycol, trialkylene glycol, and polyalkylene glycol are reduced, and monoalkylene glycol can be obtained with relatively high selectivity.

Hereinafter, the method of the present invention will be specifically explained using examples, but it goes without saying that these are merely illustrative examples and the present invention is not limited by these examples. Of course, various implementations may be made within the scope.

Here, the conversion rate of alkylene oxide, the selectivity of monoalkylene glycol, dialkylene glycol, trialkylene glycol, etc. are derived from the following formula. Example 1 In a stainless steel autoclave with an internal volume of 200 m1 and equipped with a stirrer, 30 m1 of 20.3y1 chlorine type anion exchange resin (DOwex MSA-1 manufactured by The Tau Co., Ltd.) was charged with ion-exchanged water, and the inside of the system was immediately flushed with carbon dioxide gas. After substitution, 33.0f of liquefied ethylene oxide was injected under pressure with carbon dioxide gas.

Furthermore, the system pressure was increased to 6k9/CllG with carbon dioxide gas.
After that, the autoclave was immersed in an oil bath at 150°C to carry out a reaction.

Pressure is 12kg/C7l after 20 minutes! After rising to G, it suddenly dropped to 4.3k9/CIiG and rose again to 6k9/DG.

The reaction solution temperature was a maximum of 130C. The autoclave was taken out from the oil bath, and after cooling, the contents were passed through a glass filter and the resulting mouth fluid was analyzed, and no unreacted ethylene oxide was observed, and the results are as shown in Table 1.

Example 2 In Example 1, a catalytic anion exchange resin (the
The same procedure as in Example 1 was conducted except that DOwex MSA-1 (manufactured by I-Tau) was changed from the chlorine type to the iodine type.

The results were as shown in Table 1. Comparative Example 1 The same procedure as in Example 1 was carried out except that the carbon dioxide gas in Example 1 was replaced with nitrogen gas.

The results were as shown in Table 1. Comparative Example 2 The same procedure as in Example 1 was conducted except that the halogen-type anion exchange resin was not used.

Claims (1)

[Claims] 1. A method for producing alkylene glycol, which comprises using a halogen-type anion exchanger as a catalyst in the presence of carbon dioxide when producing alkylene glycol by the reaction of alkylene oxide and water.