JPH0645563B2 - Method for producing ethylene glycol and / or propylene glycol - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing ethylene glycol and / or propylene glycol.

More specifically, a hydration reaction of ethylene oxide and / or propylene oxide (hereinafter, generally referred to as lower alkylene oxide) is carried out using a metal salt of formic acid as a catalyst to give ethylene glycol and / or propylene glycol (hereinafter, as a general rule). (Generally referred to as lower alkylene glycol).

Incidentally, lower alkylene glycol is polyester,
It is a compound useful as a raw material for antifreeze, polyether polyol, wetting agent, surfactant and the like.

(Prior Art) Conventionally, as a method for producing a lower alkylene glycol, a lower alkylene oxide which is an epoxy compound and water are used under non-catalytic conditions or under an acid catalyst (a mineral acid such as sulfuric acid is used exclusively). The method of hydration reaction in the presence is widely adopted industrially (eg, Chemical Industry Association, Process Compilation, pages 507-510, 585-589 (Tokyo Kagaku Dojin, published March 3, 1968). ), Edited by SA Miller. Ethylene and i
ts Industrial Derivatives. pp. 588-594 (Ernest Benn
Ltd., published 1969)].

However, according to this method, it is necessary to suppress by-products of multimers such as diethylene glycol, triethylene glycol, dipropylene glycol, and tripropylene glycol, which are less demanded in the market as much as possible. Since it is unavoidable to use a large excess of water of about 30 mol times, the target lower alkylene glycol can be obtained as a low-concentration aqueous solution.

Therefore, when the reaction mass after the hydration reaction is concentrated, dehydrated, and rectified, a large amount of energy is consumed in the final product, which is economically disadvantageous.

Although the use of a base catalyst has the effect of accelerating the hydration reaction, it usually increases the by-product ratio of the polymer as compared with the non-catalyst or acid-catalyzed hydration reaction described above. The selectivity of lower alkylene glycol tends to decrease (for example, the above-mentioned Ethylene and its Industrial Derivative
s. 594. See lines 16 to 24), so the fact is that the hydration reaction with a base catalyst has not been carried out industrially.

On the other hand, in recent years, as a method for overcoming the above-mentioned drawbacks of the production method, a lower alkylene oxide and water in an amount close to a stoichiometric amount are used, and a tetraalkylammonium salt or a quaternary phosphonium salt is catalyzed in the presence of carbon dioxide. Has been proposed as a method for carrying out a high-concentration hydration reaction (for example, Japanese Patent Publication No.
48 publication. See Japanese Examined Patent Publication No. 55-47617).

(Problems to be Solved by the Invention) However, the above-mentioned method for carrying out the hydration reaction in the coexistence of carbon dioxide is not sufficiently satisfactory in terms of the performance and cost of the catalyst to be used, and the reaction conditions Some of them also have a drawback that a cyclic carbonic acid ester, which is a reaction product of a lower alkylene oxide and carbon dioxide, that is, etalene carbonate and propylene carbonate are by-produced in a considerably large amount.

Further, the production method of lower alkylene glycol using these carbon dioxide requires a considerably high reaction pressure as compared with the above-mentioned industrial production method which is widely used at present, so that the construction cost of the plant is relatively high. It has the drawback that

Therefore, under the present circumstances, the development of a new hydration reaction technique that enables a high-concentration hydration reaction of lower alkylene oxide and that can more advantageously produce lower alkylene glycol with a high selectivity and a high yield is currently desired. is there.

(Means for Solving Problems) The inventors of the present invention focused on a high-concentration hydration reaction technique based on a new idea of not using carbon dioxide in order to overcome the defects of the conventional techniques, and in particular, As a result of extensive and detailed examination of the hydration reaction with a base catalyst whose practical value has not been recognized or a catalyst similar thereto, surprisingly, the metal salt of formic acid was found to have high concentration under the hydration reaction conditions. Even in this case, it was found that a polymer and a by-product were suppressed and a good catalytic action was exhibited, and the present invention was completed.

That is, the present invention is a method for producing ethylene glycol and / or propylene glycol, which comprises using a metal salt of formic acid as a catalyst in the hydration reaction of ethylene oxide and / or propylene oxide.

The present invention will be described in detail below.

The starting materials to which the method of the present invention is applied are ethylene oxide and propylene oxide. Usually, these are individually subjected to a hydration reaction and used for the production of ethylene glycol or propylene glycol, but it is also possible to use both together.

Next, the water as the other starting material is not particularly limited, and tap water, ion-exchanged water, condensed water of steam, and crude water-containing lower alkylene glycol in the lower alkylene glycol production apparatus according to the method of the present invention are used. Condensed water or the like that is recovered when concentrating or dehydrating can be arbitrarily used.

The amount of water used with respect to the lower alkylene oxide can be reduced to a stoichiometric amount, and may be less than the stoichiometric amount depending on the reaction mode, but from a practical viewpoint, it is at least equal to or higher than the stoichiometric amount. It is desirable to use water.

Specifically, the amount of water is about 1 to 15 mol times, preferably 1 to 7 mol times, and more preferably 1 to 5 mol times, per mol of the lower alkylene oxide.

Although water can be used in a larger amount than 15 times by mole, use of a large amount of water is energetically disadvantageous as described above, and the above range is practically sufficient.

Particularly in the case of the present invention, the permissible limit of the by-product rate of the multimer such as dialkylene glycol and trialkylene glycol, the concentration after the hydration reaction, the dehydration, and the energy consumption in the whole production process including the rectification process From a comprehensive viewpoint of reduction and the like, it is most advantageous to keep the amount of water to the necessary minimum amount of about 1 to 3 mol times per mol of the lower alkylene oxide.

The catalyst used in the method of the present invention is a metal salt of formic acid, specifically, an alkali metal salt such as lithium salt, sodium salt, potassium salt, etc., an alkaline earth metal salt such as magnesium salt, calcium salt, barium salt, etc., Typical examples are copper group metal salts, zinc group metal salts, aluminum group metal salts, titanium group metal salts, manganese group metal salts, iron group metal salts and the like. Particularly, formic acid alkali metal salts and alkaline earth metal salts. Is most preferably used.

Incidentally, according to the results of studies conducted by the present inventors, metal salts of aliphatic lower monovalent carboxylic acids such as acetic acid and propionic acid also have some catalytic effect, but their performance is higher than that of formic acid metal salts. It is far inferior and cannot be put to practical use. Further, metal salts of aromatic carboxylic acids such as benzoic acid and metal salts of aliphatic divalent carboxylic acids such as oxalic acid, malonic acid and succinic acid show almost no catalytic action. Therefore, the excellent effect of the present invention is considered to be a property peculiar to the metal salt of formic acid.

The metal salt of formic acid described above does not necessarily have to be prepared in advance. For example, in the case of an alkaline metal salt of formic acid, free formic acid and an alkaline metal simple substance, alkaline metal water At least one kind of an alkaline metal compound selected from the group consisting of an oxide, an alkaline metal salt, an alkaline metal hydrogen carbonate, an alkaline metal compound and the like is separately charged into a hydration reactor, It is also possible to use a method of forming both salts, that is, an alkali metal salt of formic acid in the reactor. Of course, the case of using such a method is also included in the scope of the present invention. The amount of the catalyst used cannot be uniformly defined because it depends on the type of metal salt and the like, but is usually 1 to 50 mol%, preferably 2 to 30 mol%, and most preferably 1 mol per 1 mol of the lower alkylene oxide. It is 3 to 20 mol%.

When the amount of the catalyst used is less than the above lower limit value, the effect is not sufficiently exhibited, and when the amount exceeds the upper limit value and a large amount is used, it is not economical and the above range is preferable.

The hydration reaction is usually carried out in a liquid phase, and the reaction formation may be a batch system, a semi-batch system, or a continuous system. The type of the reactor is 3 types of lower alkylene oxide, water and catalyst.
There is no particular limitation as long as it is designed so that a person can sufficiently contact it and remove the heat of reaction, and for example, a stirred tank reactor, a tubular reactor, etc. can be arbitrarily used. . The reaction temperature varies depending on the type and amount of catalyst used, the type of lower alkylene oxide, the molar ratio of lower alkylene oxide and water, etc., and cannot be specified uniformly, but it is usually 30 to 300 ° C., preferably 50. ~ 250 ° C, most preferably 80-200 ° C.

The reaction pressure is preferably such that the lower alkylene oxide as a raw material maintains a liquid phase, and is usually 0 to 50 kg / cm ² G, preferably 3 to 40 kg / cm ² G, and most preferably 5 to 30 kg / cm ² G.
Is.

After completion of the hydration reaction, water and catalyst present in the reaction product are removed by an arbitrary method, and the target lower alkylene glycol is purified by distillation or the like, whereby a highly pure product can be obtained. .

Since the catalyst is not substantially consumed, it is more economical if it is recovered and reused.

(Operation) According to the production method of the present invention, the amount of water used in the hydration reaction can be significantly reduced, and a high-concentration hydration reaction is possible. Therefore, the reaction mass after the hydration reaction is low. Obtained as a highly concentrated aqueous solution of alkylene glycol. Moreover, the target lower alkylene glycol can be produced with high selectivity and high yield. Another major feature is that it does not require the combined use of a third component such as CO ₂ .

Therefore, it is extremely advantageous from the viewpoint of energy saving and resource saving, and has high industrial utility value.

(Example) Hereinafter, the present invention will be described in more detail with reference to an example.

Example 1 Propylene oxide was placed in a stainless steel autoclave with an internal volume of 200 ml equipped with a stirrer, a thermometer and a pressure gauge.
58g (1mol), water 36g (2mol) and sodium formate
After charging 2.04 g (0.03 mol), the autoclave was placed in an electric furnace, the internal temperature was raised to 160 ° C. with stirring, and the reaction was carried out at that temperature for 1 hour.

The reactor was heated up to a maximum of 15 kg / cm ² G, then the internal pressure decreased as the hydration reaction proceeded, and the internal pressure at the end of the reaction was 5 kg / cm ^2.
It was cm ² G.

Next, after cooling the autoclave to room temperature, a part of the reaction solution was sampled and subjected to quantitative analysis of unreacted propylene oxide and the products propylene glycol, dipropylene glycol and tripropylene glycol by a gas chromatography method. The results are shown in the table.

Examples 2 to 9 The same autoclave as in Example 1 was used to carry out the hydration reaction of propylene oxide by variously changing the charged amount, the kind and the charged amount of the catalyst, the reaction temperature and the like to the raw materials as described in the table. . The results are shown in the table.

Comparative Example 1 The hydration reaction of propylene oxide was carried out under the same conditions as in Example 1 except that no catalyst was used. The results are shown in the table.

Comparative Example 2 Sodium acetate 2.46 was used in place of the sodium formate of Example 1.
Hydration reaction of propylene oxide was performed under the same conditions as in Example 1 except that g (0.03 mol) was used. The results are shown in the table.

Comparative Example 3 The hydration reaction of propylene oxide was performed under the same conditions as in Example 1 except that 4.32 g (0.03 mol) of sodium benzoate was used instead of the sodium formate of Example 1. The results are shown in the table.

Comparative Example 4 The hydration reaction of propylene oxide was performed under the same conditions as in Example 1 except that 4.02 g (0.03 mol) of disodium oxalate was used instead of the sodium formate of Example 1. The results are shown in the table.

Example 10 Ethylene oxide was added to the same autoclave as in Example 1.
44 g (1 mol), water 36 g (2 mol) and sodium formate
After charging 6.8 g (0.1 mol), the temperature was raised to 140 ° C. with stirring, and the reaction was carried out at that temperature for 1 hour.

As a result of analyzing the reaction solution by the same method as in Example 1, the conversion rate of ethylene oxide was 100%, and the composition of the product was 91.5% by weight of ethylene glycol, 7.8% by weight of diethylene glycol, and triethylene glycol. It was 0.7% by weight.

(Effects of the Invention) As described in detail in the above Examples and Comparative Examples, the method for producing ethylene glycol and / or propylene glycol of the present invention is a method for producing ethylene glycol and / or propylene oxide in water using a metal salt of formic acid as a catalyst. The current industry Ethylene glycol and / or the target product even in the hydration reaction in which the concentration of ethylene oxide and / or propylene oxide is significantly higher than that of the conventional production method (catalytic hydration method or mineral acid catalyst hydration method). It is also clear that propylene glycol can be produced with high selectivity and high yield.

Claims (7)

[Claims] 1. A method for producing ethylene glycol and / or propylene glycol, which comprises using a metal salt of formic acid as a catalyst in the hydration reaction of ethylene oxide and / or propylene oxide. 2. The amount of formic acid metal salt used relative to ethylene oxide and / or propylene oxide is 1 to 50 mol%.
The method of claim 1 wherein: 3. The amount of formic acid metal salt used is 2 to 30 mol% based on ethylene oxide and / or propylene oxide.
The method of claim 2 wherein: 4. The method according to claim 1 or 2, wherein the metal salt of formic acid is an alkaline metal salt of formic acid. 5. The method according to any one of claims 1 to 3, wherein the metal salt of formic acid is an alkaline earth metal salt of formic acid. 6. The method according to claim 1, wherein the amount of water used is 1 to 15 mol times per mol of ethylene oxide and / or propylene oxide. 7. The method according to claim 6, wherein the amount of water used is 1 to 3 mol per mol of ethylene oxide and / or propylene oxide.