JP2001031601A - Production of highly pure monoethylene glycol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing monoethylene glycol by which the generation of ethylene chlorohydrin is prevented at the time of purification of monoethylene glycol by fixing the inorganic chlorine generated in a hydration reaction liquid, before the chlorine is fed to a monoethylene glycol-purifying column in the method for producing the monoethylene glycol by using an unpurified crude ethylene oxide as a raw material for hydration reaction. SOLUTION: This method for producing monoethylene glycol by using an unpurified crude ethylene oxide containing a chlorine compound comprises adding alkaline material in an amount regulated so that the atomic equivalent may be >=0.5 based on 1 atom inorganic chlorine generated in a hydration reaction liquid after the hydration reaction, and feeding the resultant liquid to a rectifier 107 of monoethylene glycol to purify the monoethylene glycol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a silver catalyst in the presence of a silver catalyst.
Unrefined crude ethylene oxide containing chlorine compounds obtained in the process of purifying ethylene oxide by catalytic gas phase oxidation of ethylene with molecular oxygen is used as a raw material for the hydrolysis reaction, and it has fiber grade quality and thermal stability. The present invention relates to a method for producing good high-purity monoethylene glycol.

[0002]

2. Description of the Related Art Conventionally, an ethylene glycol obtained by using crude crude ethylene oxide obtained in a process of purifying ethylene oxide by catalytic vapor phase oxidation of ethylene with molecular oxygen in the presence of a silver catalyst as a raw material for a hydrolysis reaction. (1) As described in JP-B-61-3772, vapor coming from the top of an ethylene oxide stripping tower is condensed in two condensers, and the condensate is refluxed to the stripping tower. There is a method in which the uncondensed gas is sent to a third condenser to be condensed, and the condensate is sent to a hydrolysis reactor to carry out a glycolation reaction. Further, (2) In the method described in US Pat. No. 3,904,656, a gas coming from the top of a stripping tower is led to a reabsorbing tower, where the gas is absorbed by an absorbing solution containing water as a main component, and the absorbing solution having absorbed ethylene oxide is hydrolyzed. The reaction is sent to the reactor. Also, (3) JP-B-54-882 discloses that the gas at the top of the stripping tower is condensed by a condenser, the condensate is returned to the stripping tower as reflux, and the uncondensed gas is guided to the reabsorbing tower and absorbed. There is a method in which an absorbing solution having absorbed the obtained ethylene oxide is introduced into a water reactor to cause a reaction.

Japanese Unexamined Patent Publication No. Sho 56-104829 discloses a process for producing high-purity monoethylene glycol, which comprises adding an alkali metal between a hydrolysis reactor and a monoethylene glycol rectification column for distilling off monoethylene glycol from the top. The aqueous solution of the compound is added to the reaction product, and the reaction product when entering the monoethylene glycol rectification column has a pH of 7 to 10.
A process for producing high-purity monoethylene glycol, characterized in that it is added to the reaction product in an amount having a value, is disclosed. However, the above-mentioned JP-A-56-104829
In the invention described in Japanese Patent Application Laid-Open Publication No. H11-150, the contamination of the organic chlorine compounds such as ethylene dichloride and ethylene chlorohydrin is not mentioned in ethylene oxide (crude ethylene oxide) as the raw material for the hydrolysis reaction, and these organic chlorine compounds are contained. There is no disclosure of a technical problem that arises when a raw material for a hydrolysis reaction is used and a solution to the technical problem.

[0004] The present applicant also discloses in Japanese Patent Publication No. 61-3772, for example, crude crude ethylene oxide obtained in the process of purifying ethylene oxide by catalytic gas phase oxidation of ethylene with molecular oxygen in the presence of a silver catalyst. We have proposed a method for producing high-purity monoethylene glycol used as a raw material for the hydrolysis reaction.However, there is no need to consider measures for inorganic chlorine caused by chlorine compounds in crude ethylene oxide. No purification of monoethylene glycol was carried out.

Therefore, a method for producing high-purity monoethylene glycol using unpurified crude ethylene oxide containing an organic chlorine compound as a raw material for the hydrolysis reaction has not been proposed so far. It can be said that there is.

[0006]

As in the conventional method, the gas at the top of the ethylene oxide stripping tower is condensed, the condensate is refluxed, and the water obtained by cooling or absorbing the uncondensed gas undergoes a hydrolysis reaction. In this case, the chlorine compound is transferred to the first-stage condensate or the bottom liquid, so that the chlorine compound is not mixed into ethylene oxide obtained from the first-stage uncondensed gas. Therefore, it can be said that ethylene glycol obtained by hydrolyzing the ethylene oxide contains only a trace of these chlorine compounds.

[0007] However, the present inventors, without being satisfied with the prior art, have tried to convert ethylene into molecular form in the presence of a silver catalyst for the purpose of further simplifying the process of producing monoethylene glycol and saving energy. In the process of purifying ethylene oxide obtained by catalytic gas phase oxidation with oxygen, it was examined whether crude crude ethylene oxide obtained without refluxing the top of the ethylene oxide stripping tower could be used as a raw material for the hydrolysis reaction did. As a result, when unpurified crude ethylene oxide was used as a raw material for the hydrolysis reaction,
The heating stability of the resulting monoethylene glycol product was insufficient, and a fiber grade product could not be obtained.

That is, in the process of purifying ethylene oxide by catalytic gas-phase oxidation of ethylene with molecular oxygen in the presence of a silver catalyst, the organic chlorine compounds such as ethylene dichloride and ethylene chlorohydrin are combined with ethylene oxide and the like to form ethylene oxide. It comes out from the top of the stripping tower. Although such organic chlorine compounds are removed by a subsequent distillation separation operation, if the condensate obtained from the gas coming from the top of the ethylene oxide stripping tower is used as it is as a raw material for the hydrolysis reaction, It has been found that the obtained monoethylene glycol is contaminated with a chlorine compound in an amount corresponding to about 20% of the organic chlorine compounds in the raw material for the hydrolysis reaction.

The inventors of the present invention have conducted intensive studies to determine the cause, and as a result, have found that organic chlorine compounds such as ethylene dichloride contained in the unpurified crude ethylene oxide (the molecular weight of ethylene in the presence of a silver catalyst is reduced). (Added during the process of producing ethylene oxide by catalytic gas phase oxidation with oxygen in the form of oxygen)), inorganic chlorine is generated in the hydrolysis reaction solution, and impurities such as ethylene chlorohydrin are generated during the ethylene glycol dehydration process. It was found that the quality of the product monoethylene glycol, such as thermal stability, deteriorated because it was mixed with the rectified monoethylene glycol.

Accordingly, an object of the present invention is to simplify the production process and operation and achieve energy saving in a process for producing monoethylene glycol, and to reduce impurities such as ethylene chlorohydrin in a monoethylene glycol product. It is an object of the present invention to provide a method for producing high-purity monoethylene glycol which can suppress contamination and satisfy the product specification value required for fiber-grade high-purity monoethylene glycol.

[0011] Another object of the present invention is to provide a monoethylene glycol product obtained by using purified ethylene oxide as a raw material for a hydrolysis reaction even if crude ethylene oxide containing a chlorine compound is used as a raw material for a hydrolysis reaction. It is another object of the present invention to provide a production method capable of obtaining a fiber grade high-purity monoethylene glycol product having high heat stability, in which impurities are suppressed from being mixed.

[0012]

Means for Solving the Problems In order to achieve the above objects, the present inventors have conducted intensive studies on a method for producing high-purity monoethylene glycol. As a result, the present inventors obtained the method without refluxing the top of the ethylene oxide stripping tower. The crude crude ethylene oxide containing the chlorine compound is used as a raw material for the hydrolysis reaction to save energy, and a complicated treatment form and equipment are used for new impurities attributed to the crude crude ethylene oxide. By using an extremely simple means without adding or adding many steps, inorganic chlorine that cannot be removed by ordinary distillation operation and is generated by decomposition of a part of the organic chlorine compound After fixing, the monoethylene glycol is purified in a monoethylene glycol rectification column to obtain ethylene chlorohydride as an impurity. Suppressing the generation of organic chlorine compounds such as down, we found that it is possible to prevent infiltration into the product, and have reached to complete the present invention. That is, the object of the present invention is achieved by the following (1) to (6).

(1) In a method for producing monoethylene glycol by using crude crude ethylene oxide containing a chlorine compound as a raw material for a hydrolysis reaction, one atom of inorganic chlorine contained in the hydrolysis reaction solution after the hydrolysis reaction A method for producing high-purity monoethylene glycol, characterized in that an alkaline substance is added so as to have an atomic equivalent of 0.5 or more, and then supplied to a monoethylene glycol rectification column for purification.

(2) The method according to the above (1), wherein the alkaline substance to be added is an oxide, hydroxide or basic salt of an alkali metal or alkaline earth metal.

(3) The above (1) or (2), wherein the amount of alkali to be added is in the range of 0.5 to 2 atomic equivalents per 1 atom of inorganic chlorine in the hydrolysis reaction solution. the method of.

(4) The crude crude ethylene oxide containing the chlorine compound is obtained by condensing part or all of the ethylene oxide-containing vapor obtained from the top of the ethylene oxide stripping tower by cooling and / or absorption. The method according to any one of the above (1) to (3), wherein the condensate obtained is ethylene oxide.

(5) The crude liquid obtained by condensing part or all of the ethylene oxide-containing vapor obtained from the top of the ethylene oxide stripper with the crude crude ethylene oxide containing the chlorine compound, The method according to any one of the above (1) to (4), which is obtained without refluxing in the column.

(6) The crude crude ethylene oxide containing the chlorine compound partially condenses the ethylene oxide-containing vapor obtained from the top of the ethylene oxide stripping tower to obtain a first condensate, and the remaining crude The above-mentioned (1) to (5), wherein the condensed gas is further condensed or introduced as it is into an ethylene oxide dehydration tower, and the obtained dehydrated ethylene oxide is mixed with the first condensate. The method according to any one of the preceding claims.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing high-purity monoethylene glycol according to the present invention comprises the steps of: using unpurified crude ethylene oxide containing a chlorine compound as a raw material for a hydrolysis reaction; After that, after adding an alkaline substance so as to have an atomic equivalent of 0.5 or more with respect to one atom of inorganic chlorine present in the hydrolysis reaction liquid, the resultant is supplied to a monoethylene glycol rectification column for purification. Is what you do. In this way, in the process up to the purification of monoethylene glycol, the inorganic chlorine generated in the hydrolysis reaction solution is fixed in a stable form that can be easily separated from monoethylene glycol, and is removed from the bottom liquid side of the rectification column. Can be. As a result, the contamination of impurities caused by inorganic chlorine into the monoethylene glycol fraction can be suppressed, so that the quality of the rectified monoethylene glycol after heating, for example, the ultraviolet transmittance, can be greatly increased. A fiber grade high-purity monoethylene glycol product having high heat stability can be obtained.

As the crude crude ethylene oxide containing a chlorine compound, which is a raw material for a hydrolysis reaction, which can be used in the production method of the present invention, ethylene is subjected to catalytic gas phase oxidation with molecular oxygen in the presence of a silver catalyst. Any crude crude ethylene oxide containing chlorine compounds obtained in the process of purifying ethylene oxide is not particularly limited, but from the viewpoint of further simplifying the production process / operation and saving energy, What is obtained without refluxing the condensate of the vapor at the top of the stripping tower is preferred.

Unpurified crude ethylene oxide used in the conventional method can be used. For example, the above-mentioned JP-B-61-3772, US Pat. No. 3,904,656,
JP-B-54-882 or JP-A-52-3661.
Unrefined crude ethylene oxide used in the method described in, for example, Japanese Patent Publication No. B. overhead fraction of ethylene oxide stripping tower; B. overhead fraction of ethylene oxide dehydration tower, B. bottom liquid of ethylene oxide dehydration tower; A bottom liquid of an ethylene oxide rectification column, and E. And a bottom liquid of a reabsorption tower. These may be used alone or as a mixture of two or more.

Furthermore, the present inventors have conducted intensive studies from the viewpoint of simplification of the process and reduction of the size of equipment such as a condenser and a reflux pump at the top of the column, and as a result, have found the following chlorine compounds shown below. Crude crude ethylene oxide containing compounds. In the case of crude crude ethylene oxide shown below, in the above case, a large amount of water and ethylene oxide are returned to the ethylene oxide stripping tower, so that the amount of steam consumed in the ethylene oxide stripping tower increases, or the amount of introduced steam is large. Unreacted crude ethylene oxide sent to the hydrolysis reactor, whereas a large amount of absorption liquid is required because it contains water and a large amount of energy is required when dehydrating from glycol after performing the hydrolysis reaction. This is preferable in that steam coming out from the top of the ethylene oxide stripping tower can be reduced without diluting the aqueous solution.

The ethylene oxide-containing vapor obtained from the top of the ethylene oxide stripping tower is cooled and / or cooled.
Or ethylene oxide in a condensed liquid obtained by condensing part or all of the condensate by absorption, condensed liquid obtained by condensing part or all of ethylene oxide-containing vapor obtained from the top of the ethylene oxide stripping tower, The first condensate is obtained by partially condensing the product obtained without refluxing into the stripper and the ethylene oxide-containing vapor obtained from the top of the ethylene oxide stripper, and further condensing the remaining uncondensed gas Alternatively, at least one of the resulting dehydrated ethylene oxide mixed with the first condensate may be used as a suitable raw material for a hydrolysis reaction.

In the present invention, except for the operation of adding an alkaline substance so as to have an atomic equivalent of 0.5 or more with respect to 1 atom of inorganic chlorine generated from a chlorine compound present in the reaction solution after the hydrolysis reaction, The method is not limited, and a conventionally known method can be appropriately used, as described in JP-B-61-3772, US Pat.
6, by the conventionally known production method described in JP-B No. 54-882 and the like, the raw material for the hydrolysis reaction is reacted in a reactor, the reaction product is distilled water in a plurality of distillation columns, water and A method of sequentially distilling low boiling components from monoethylene glycol and then distilling monoethylene glycol to obtain high-purity monoethylene glycol can be appropriately used.

The term "hydrolysis reaction solution" as used in the present invention refers to a reaction product obtained by subjecting the above-mentioned hydrolysis reaction raw material to a hydrolysis reaction in a reactor, or a monoethylene glycol obtained by distilling the reaction product. Any one of the reaction products before the distillation product is used. That is, in the present invention, the alkaline substance is used after the hydrolysis reaction operation and before the monoethylene glycol distillation operation, in other words,
The monoethylene glycol may be added after the water reactor and before the column which distills off from the top. That is, the timing of addition of the alkaline substance to the hydrolysis reaction solution is as described above, and is not particularly limited as long as the immobilization of inorganic chlorine is optimally performed, and one step (location) Or a plurality of steps (locations), and may be added all at once, or may be added continuously. However, since the substance that interferes with the effect of alkali addition is the least, It is desirable to add an alkaline substance in a line fed from the bottom of the ethylene glycol dehydration column to the monoethylene glycol rectification column.

The alkaline substance that can be used in the present invention is not particularly limited as long as it is a substance that dissolves in water and shows basicity, and may be an oxide of an alkali metal or an alkaline earth metal. , Hydroxides and carbonates are preferred. Therefore, specific examples of the alkaline substance include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide, hydroxides of alkaline earth metals such as magnesium hydroxide and calcium hydroxide, and sodium carbonate. And sodium bicarbonate, but hydroxides of alkali metals and alkaline earth metals are preferred because of their high solubility in glycols. Also,
In the present invention, these alkaline substances may be used alone or in a mixture of two or more at an appropriate ratio.

The amount of the alkaline substance to be added is not particularly limited as long as the inorganic chlorine contained in the hydrolysis reaction solution can be suitably immobilized. It may be added, but preferably, an alkaline substance is added in an amount of 0.5 or more, more preferably 0.5 to 2, to 1 atom of inorganic chlorine generated in the reaction solution.
It is particularly desirable to add so as to have an atomic equivalent of 0.5 to 1. When the alkaline substance has an atomic equivalent of less than 0.5 with respect to one atom of the inorganic chlorine generated in the hydrolysis reaction liquid, the inorganic chlorine contained in the bottom liquid of the monoethylene glycol dehydration tower, particularly the monochlorinated water dehydration tower, is used. Insufficient inorganic chlorine component reacts with ethylene glycol in the monoethylene glycol purification tower to produce ethylene chlorohydrin, which is insufficient to sufficiently immobilize, and is mixed into the monoethylene glycol product . Therefore, when this monoethylene glycol product is heated, methyl dioxolane is generated due to the presence of ethylene glycol and ethylene chlorohydrin, which causes a deterioration in ultraviolet transmittance after heating. On the other hand, when the alkaline substance has an atomic equivalent of more than 2 with respect to one atom of the inorganic chlorine generated in the reaction solution, even if a monovalent alkali metal hydroxide or the like is used, the alkaline substance may be used. The inorganic chlorine can be sufficiently immobilized by the addition, and there is no particular problem in this respect. However, no further effect corresponding to the excessive addition having an atomic equivalent exceeding 2 is obtained, and the excess alkalinity is not obtained. This is not preferable in that it is uneconomical, for example, the amount of waste liquid when separating substances is increased. It should be noted that the pH of the hydrolysis reaction solution is increased by the addition of the alkaline substance. Since the composition of the target hydrolysis reaction solution varies depending on the timing of adding the alkaline substance, the pH of the hydrolysis reaction liquid after the addition of the alkaline substance cannot be uniquely defined, but increases to approximately 5 to 9 But 5-7
Is enough.

The exact amount of the inorganic chlorine in the hydrolysis reaction solution can be measured by a measuring method such as ion chromatography.

The form of addition of the alkaline substance is not particularly limited, and may be solid or liquid, but it is a line fed from the bottom of the ethylene glycol dehydration column to the monoethylene glycol rectification column. When adding an alkaline substance, it is not desirable to add it in the form of an aqueous solution.For example, it is recommended to use an alkaline solution diluted with high-purity monoethylene glycol to an appropriate concentration to mix water with the product. It can be said that it is preferable from the viewpoints of ease of handling and mixing, in addition to suppression of the amount.

Hereinafter, embodiments of the present invention will be described more specifically with reference to the drawings.

FIG. 1 is a partial schematic view of a typical apparatus configuration used in the method for producing high-purity monoethylene glycol according to the present invention. In the method for producing ethylene glycol, an alkaline substance is added to the line fed from the bottom of the dehydration tower to the monoethylene glycol rectification column in the amount specified above, and the pH of the feed liquid to the monoethylene glycol rectification column is adjusted. After raising to about 5,
This shows a case where monoethylene glycol is purified in a monoethylene glycol rectification column.

As shown in FIG. 1, in the apparatus configuration of this embodiment, first, crude crude ethylene oxide containing a chlorine compound is used as a raw material for a hydrolysis reaction, and the raw material for a hydrolysis reaction is used in a hydrolysis reactor. The water is allowed to react, and then the can solution (ethylene glycol) concentrated in the ethylene glycol concentration step in the evaporator is sent to the ethylene glycol dehydration tower 101 through the pipe 103. The can solution sent to the dehydration tower 101 is
It is distilled under reduced pressure at 1 and fractionated into water and ethylene glycol. The water vapor from the top of the dehydration tower 101
Distilled through 05, and all condensed and liquefied by a suitable cooling means (not shown) provided on the path of the pipe 105 (if necessary, partly returned to the dehydration column 101 as reflux through the pipe, and the rest) It is removed from the system through the pipe 105 and dehydrated. On the other hand, an ethylene glycol liquid substantially free of water is obtained at the bottom of the dehydration tower 101. The ethylene glycol liquid is withdrawn from the bottom of the dehydration column 101 through the pipe 109 and sent to the monoethylene glycol rectification column 107. At this time, an alkaline substance in an amount specified above with respect to the amount of inorganic chlorine in the ethylene glycol liquid is added to the ethylene glycol liquid flowing through the pipe 109 from the alkali storage tank (not shown) through the pipe 111. Thereby, the inorganic chlorine in the ethylene glycol liquid is fixed. Rectification tower 10
The ethylene glycol liquid sent to 7 is distilled under reduced pressure in the rectification column 107, and is fractionated into a low-boiling fraction monoethylene glycol and a high-boiling fraction such as diethylene glycol containing immobilized inorganic chlorine. . The monoethylene glycol vapor distilled from the top of the rectification column 107 is converted into a monoethylene glycol liquid which is totally condensed and liquefied by a condenser 115 provided on a pipe 113. A part of the monoethylene glycol liquid is returned to the rectification column 107 through the branch pipe 117 and returned, and the remaining monoethylene glycol liquid is
Collected as a high-purity product in a product storage tank (not shown) through 8. On the other hand, the high-boiling fraction remaining at the bottom of the rectification column 107 is sent to a diethylene glycol treatment step outside the system via a pipe 119, where the immobilized inorganic chlorine is separated and removed.

The above is a method for producing high-purity monoethylene glycol using the apparatus configuration of the present embodiment. As described above, these methods are of a continuous type, and are most suitable for producing ethylene glycol on an industrial scale. However, there is no harm in performing it in batch mode.

[0034]

EXAMPLES The present invention will now be described more specifically with reference to examples.

Example 1 A crude ethylene oxide containing chlorine compounds was obtained by condensing the vapor at the top of an EO stripper without reflux. The component composition of the crude crude ethylene oxide was 10% by weight of ethylene oxide, 55% by weight of impurities (including 2.8% by weight as an organic chlorine compound and 52% by weight of an aldehyde content in terms of acetaldehyde).
m, and remaining water. The unpurified crude ethylene oxide was used as a raw material for a hydrolysis reaction, and supplied to a pressurized reactor. The inlet temperature was 124 ° C., the outlet temperature was 165 ° C., 2.5 M
The reaction was continuously performed under Pa. Next, the mixture was concentrated and dehydrated to a glycol concentration of 90% by weight using a quadruple effect can, and the final solution in the evaporator was sent to an ethylene glycol dehydration tower.
The operation was performed under a pressure of 70 mmHg, and steam was distilled off from the top of the ethylene glycol dehydration column to perform dehydration.
On the other hand, an ethylene glycol liquid was withdrawn from the bottom of the ethylene glycol dehydration column and fed to a monoethylene glycol rectification column. At this time, while feeding from the bottom of the ethylene glycol dehydration column to the monoethylene glycol rectification column, potassium hydroxide was added so as to have an atomic equivalent of 1 atom of inorganic chlorine generated in the ethylene glycol liquid. . The amount of inorganic chlorine in the ethylene glycol solution was measured by using ion chromatography for the ethylene glycol solution extracted from the bottom of the ethylene glycol dehydration tower. Thereby, the pH of the feed solution to the monoethylene glycol rectification column was adjusted to 50
3.8 to 5.0 to 5.0.
Rose to 1. The ethylene glycol solution was purified in a monoethylene glycol rectification column, and monoethylene glycol was distilled off from the top of the rectification column and collected. The concentration of ethylene chlorohydrin in the obtained monoethylene glycol was determined using a gas chromatograph mass spectrometer (manufactured by Shimadzu Corporation:
QP-5000). Furthermore, after heating the obtained monoethylene glycol at 260 ° C. for 1 hour and 10 minutes,
The ultraviolet transmittance at 220 nm was measured with an absorptiometer (U3200, manufactured by Hitachi, Ltd.). The results of these measurements are shown in Table 1 below.

Comparative Example 1 In Example 1, without adding potassium hydroxide to the pipe fed from the bottom of the ethylene glycol dehydration column to the monoethylene glycol rectification column (therefore, the pH of the rectification column feed solution was not changed). Was not increased and the pH was 3.8), and monoethylene glycol was purified in the rectification column. The concentration of ethylene chlorohydrin in the obtained monoethylene glycol was measured with a gas chromatograph mass spectrometer (QP-5000, manufactured by Shimadzu Corporation). Further, the obtained monoethylene glycol was heated at 260 ° C. for 1 hour.
After heating for 10 minutes, the UV transmittance at 220 nm was measured with an absorptiometer (U3200, manufactured by Hitachi, Ltd.). The results of these measurements are shown in Table 1 below.

[0037]

[Table 1]

[0038]

According to the method for producing high-purity monoethylene glycol of the present invention, by using unpurified crude ethylene oxide containing a chlorine compound as a raw material for the hydrolysis reaction, the process can be simplified and energy saving can be achieved. Addition of a predetermined amount of an alkaline substance to the hydrolytic reaction solution can fix the inorganic chlorine, thereby preventing the reaction with ethylene glycol and suppressing the production of organic chlorine compounds during monoethylene glycol purification. Thus, the ultraviolet transmittance of the rectified monoethylene glycol after heating can be greatly increased, and a fiber grade high-purity monoethylene glycol product having high heat stability can be obtained.

In addition, the production method of the present invention is economically advantageous because it is only necessary to add an alkaline substance addition line to a part of the existing production equipment, and the existing production equipment can be used. is there.

Further, according to the present invention, as crude ethylene oxide which is unpurified, (1) ethylene oxide-containing vapor obtained from the top of the ethylene oxide stripping tower is obtained by condensing part or all of the vapor by cooling and / or absorption. (2) Condensate obtained by condensing part or all of the ethylene oxide-containing vapor obtained from the top of the ethylene oxide stripping tower, and (2) the condensate obtained without refluxing the stripping tower (3) Partially condensing the ethylene oxide-containing vapor obtained from the top of the ethylene oxide stripping tower to obtain a first condensate, and further condensing the remaining uncondensed gas or decomposing ethylene oxide as it is. Led to a column and the resulting dehydrated ethylene oxide was mixed with the first condensate By using at least one of the above, it is possible to save energy in the process of producing monoethylene glycol (it becomes possible to save energy more than when refluxing the top of the ethylene oxide stripping tower), which is more advantageous. .

[Brief description of the drawings]

FIG. 1 is a schematic partial process diagram of a typical apparatus used in a method for producing high-purity monoethylene glycol according to the present invention, wherein crude crude ethylene oxide is used as a raw material for a hydrolysis reaction, In the method for producing ethylene glycol, an alkaline substance is added in an amount specified above to a line fed from the bottom of the dehydration tower to the monoethylene glycol rectification column, and p of the rectification column feed liquid is added.
It is a process schematic diagram which shows the part which raises H to about 5 and refine | purifies monoethylene glycol in a monoethylene glycol rectification column.

[Explanation of symbols]

 101 ... ethylene glycol dehydration tower, 103, 105, 109, 111, 113, 117, 118, 119 ... piping, 107 ... monoethylene glycol rectification tower, 115 ... condenser.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kenji Suzuki 14-1 Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Nippon Shokubai Co., Ltd. (72) Inventor Hironori Horie 14-1 Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa Co., Ltd. Within Nippon Shokubai (72) Inventor Makoto Furukawa 14-1 Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term (reference) 4H006 AA02 AC41 AD11 BC37 BD10 BE10 BE11 BE60 FE11 FG24

Claims (6)

[Claims] 1. A method for producing monoethylene glycol using a crude crude ethylene oxide containing a chlorine compound as a raw material for a hydrolysis reaction, comprising the steps of: A method for producing high-purity monoethylene glycol, comprising adding an alkaline substance so as to have an atomic equivalent of 0.5 or more, and then supplying the purified substance to a monoethylene glycol rectification column for purification. 2. The method according to claim 1, wherein the alkaline substance to be added is an oxide, hydroxide or basic salt of an alkali metal or alkaline earth metal. 3. The method according to claim 1, wherein the amount of alkali added is in the range of 0.5 to 2 atomic equivalents per 1 atom of inorganic chlorine in the reaction solution. 4. The crude crude ethylene oxide containing a chlorine compound is obtained by condensing part or all of ethylene oxide-containing vapor obtained from the top of an ethylene oxide stripping tower by cooling and / or absorption. 4. The method according to claim 1, wherein the condensate is ethylene oxide. 5. A condensate obtained by condensing part or all of the ethylene oxide-containing vapor obtained from the top of the ethylene oxide stripping tower with the crude crude ethylene oxide containing a chlorine compound is converted to a condensate liquid. The method according to any one of claims 1 to 4, wherein the method is obtained without reflux. 6. The crude crude ethylene oxide containing a chlorine compound partially condenses a vapor containing ethylene oxide obtained from the top of an ethylene oxide stripping tower to obtain a first condensate, and obtains the remaining uncondensed liquid. 6. The gas according to claim 1, wherein the gas is further condensed or introduced as it is into an ethylene oxide dehydration tower, and the obtained dehydrated ethylene oxide is mixed with the first condensate. The method described in the section.