JPS6147813B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new method for producing ethylene glycol, and in particular, a method for producing ethylene glycol using oxalic acid diester obtained by a gas phase reaction of carbon monoxide and nitrite as a raw material. It provides a continuous process.

Ethylene glycol has many industrial uses, such as as a raw material for polyester fibers, a raw material for alkyd resins, a cold-resistant coolant, a solvent, or a reagent.

Conventionally, there has been known a method for producing ethylene glycol by bringing oxalic acid diester into gas phase contact with hydrogen under a hydrogenation catalyst. Furthermore, as a method for producing oxalic acid diester, a method of bringing carbon monoxide and nitrite into gas phase contact under a platinum group metal catalyst is also known.

This invention provides a continuous process that can industrially advantageously produce ethylene glycol from carbon monoxide, nitrite, and hydrogen by skillfully combining the oxalate diester production method and the ethylene glycol production method. It is something to do.

That is, this invention provides: (1) carbon monoxide and nitrite ester-containing gas,
A first step of contacting a platinum group metal solid catalyst in the gas phase to obtain a product containing an oxalic acid diester; (2) condensing the product of the first step to obtain the monoxide produced in the contact reaction of the first step; a second step of separating into a non-condensable gas containing nitrogen and a condensate containing oxalic acid diester; (4) The condensate containing the oxalic acid diester in the second step is brought into contact with hydrogen in the gas phase to a hydrogenation catalyst, a fourth step of obtaining a product containing glycol; (5) a fifth step of distilling the product in the fourth step to distill off alcohol to obtain ethylene glycol; (6) a step of distilling the alcohol in the fifth step into a This invention relates to a continuous method for producing ethylene glycol, which consists of each step, including the sixth step, in which the alcohol is supplied as an alcohol source for three steps.

Next, each step of this invention will be explained.

First step: A raw material gas containing carbon monoxide and nitrite is introduced into a reactor filled with a platinum group metal solid catalyst and subjected to a catalytic reaction in the gas phase.

A single-tube or multi-tubular catalyst packed column is effective as the reactor, and the contact time between the platinum group metal solid catalyst and the raw material gas is set to be 10 seconds or less, preferably 0.2 to 5 seconds. is desirable.

Palladium is the most effective platinum group metal solid catalyst, but platinum, rhodium, ruthenium, iridium, etc. are also useful, and nitrates, nitrates, phosphates, halides, acetates, oxalates, Salts such as benzoates also come into use. These include, for example, activated carbon, alumina,
It is used supported on an inert carrier such as silica, silica-alumina, diatomaceous earth, pumice, magnesia, zeolite, and molecular sieve. In addition, the amount used is 0.01 to 0.01 to the carrier in terms of platinum group metal.
10% by weight, usually in the range 0.2-2% by weight.

Carbon monoxide and nitrite ester-containing gases, which are raw material gases, are usually used after being diluted with a gas inert to the reaction, such as nitrogen gas or carbon dioxide gas.

The nitrite ester is preferably an ester of nitrous acid and a saturated monovalent aliphatic alcohol or alicyclic alcohol having 1 to 8 carbon atoms, and examples of the alcohol component include methanol, ethanol,
n-(and iso-)propanol, n-(iso-)
-, sec-, tert-) butanol, n- (and
iso-)amyl alcohol, hexanol, aliphatic alcohols such as octanol, and alicyclic alcohols such as cyclohexanol, methylcyclohexanol, etc. These alcohols include, for example, It may contain substituents that do not inhibit the reaction. Among these, it is preferable to use methyl nitrite and ethyl nitrite.

This reaction needs to be carried out under conditions such that no liquid phase is formed in the reaction zone. The conditions under which a liquid phase is not formed in the reaction zone vary depending on conditions such as reaction temperature, reaction pressure, type of nitrite ester, and concentration used, and cannot be uniformly determined.

However, regarding the reaction temperature, the reaction proceeds sufficiently quickly even at low temperatures, and the lower the reaction temperature, the fewer side reactions occur, so as long as the desired space-time yield is maintained, the reaction temperature is relatively low, that is, usually 50 to 200°C, preferably. is carried out at a temperature of 80-150°C. Regarding the reaction pressure, the reaction is usually carried out at a pressure of normal pressure to 10 kg/cm ² (gauge pressure), preferably normal pressure to 5 kg/cm ² (gauge pressure), and in some cases slightly lower than normal pressure. It may be under pressure.

The concentration of nitrite ester in the raw material gas can be varied over a wide range, but in order to obtain a satisfactory reaction rate, it is necessary to have the nitrite present at a concentration of 1% by volume or more; It is 5 to 30% by volume.

The concentration of carbon monoxide in the feed gas may vary over a wide range and is usually chosen in the range of 10 to 90% by volume.

Second Step The product from the first step is introduced into a condenser, cooled to a temperature at which the oxalic acid diester in the product condenses, and then separated into a condensed liquid and a non-condensable gas.

The main component of this separated condensate is oxalic acid diester. On the other hand, the non-condensable gas contains unreacted carbon monoxide, nitrite ester, etc. in addition to nitrogen monoxide generated in the contact reaction in the first step.

In this step, a part of the oxalic acid diester is entrained in the non-condensable gas, which is hydrolyzed by the water generated during the regeneration of nitrogen monoxide into nitrite ester in the third step described below, and the oxalic acid diester is generated. may accumulate in the gas circulation system. Also,
When the melting point is relatively high, such as dimethyl oxalate, the target substance solidifies and adheres to the walls of the condenser.
There is a fear that it will eventually become blocked.

Therefore, in order to solve these problems, the first
It is also possible to apply a method in which the product in the step is brought into contact with alcohol and cooled and condensed at a temperature below the boiling point of the alcohol. For example, if the target material is dimethyl oxalate, add 0.01 to 0.1 methanol to 100 parts by volume of the material to be treated.
It is preferable to cool and condense the liquid at a temperature of 30 to 60°C while flowing it onto the wall surface of the capacity vessel.

Third step The non-condensable gas separated in the second step is led to a regeneration tower and brought into contact with a molecular oxygen-containing gas and an alcohol solution to regenerate nitrogen monoxide in the gas into nitrite ester.

As the regeneration tower in this step, a normal gas-liquid contact device such as a packed tower, bubble tower, spray tower, or tray tower is used. The alcohol to be used is preferably the same alcohol as the alcohol component that is a constituent of the nitrite ester used above.

The non-condensable gas and the molecular oxygen-containing gas to be contacted with the alcohol can be introduced into the regeneration tower individually or in a mixed state.

In this regeneration tower, a part of nitrogen monoxide is oxidized to nitrogen dioxide, and the nitrogen monoxide is absorbed and reacted with alcohol to be regenerated into nitrite ester.

In this step, the concentration of nitrogen monoxide in the gas discharged from the regeneration tower is regulated within the range of 2 to 7% by volume, and nitrogen dioxide and oxygen are not contained in the gas as much as possible. is preferred. That is, when the concentration of nitrogen monoxide in the regenerating gas is made larger than the above-mentioned upper limit, when the gas is recycled to the reactor of the first step, the reaction rate for producing the oxalic acid diester decreases and the yield thereof decreases. On the other hand, if the concentration is lower than the lower limit, a considerable amount of nitrogen dioxide and oxygen will be contained in the regeneration gas, which will reduce the activity of the platinum group metal solid catalyst in the first step, It also becomes a factor that increases the by-product of carbon dioxide.

For this purpose, 0.08 to 0.2 mole of molecular oxygen-containing gas is supplied on an oxygen basis per 1 mole of nitrogen monoxide in the gas introduced into the regeneration tower, and these gases are kept at a temperature below the boiling point of the alcohol to be used. It is preferable to contact the alcohol with the alcohol at a temperature of 0.5 to 20 seconds. In addition, the amount of alcohol used is more than the amount necessary to completely absorb and react the nitrogen dioxide and nitrogen monoxide that are produced, and the amount of alcohol used is usually 1 part by volume of nitrogen monoxide in the gas introduced into the regeneration tower. 2 to 5 alcohol
It is preferable to use capacitive parts.

The lost nitrogen can be replenished by supplying nitrite ester to the reactor in the first step, or by supplying nitrogen monoxide, nitrogen dioxide, dinitrogen trioxide, dinitrogen tetroxide, etc. to the regeneration tower in the third step. This can also be done by introducing nitrogen oxides or nitric acid.

In addition, if the content of nitrogen monoxide in the non-condensable gas in the second step is large, and when the nitrogen monoxide is regenerated into nitrite ester in the third step, more nitrite ester than the required amount can be obtained. A part of the non-condensable gas is directly sent to the first regeneration tower without introducing the entire amount to the regeneration tower.
It may be recycled and fed to the reactor in the process.

The nitrite-containing gas discharged from the regeneration tower is recycled to the first step reactor. In addition, this regenerated gas may be mixed with carbon monoxide, another raw material, and then supplied to the reactor.The regenerated nitrite ester may be n-butyl nitrite, n-butyl nitrite, or n-butyl nitrite.
- In the case of an ester of an alcohol having 4 or more carbon atoms, such as amyl, it forms an azeotropic composition with the water produced as a by-product during the regeneration reaction, and the water is entrained in the regeneration gas. Therefore, if this gas is supplied as it is to the reactor in the first step, the water will suppress the oxalic acid diester production reaction, so it is necessary to remove the water in the gas by distillation or other operations and then recirculate it to the reactor. is preferred. On the other hand, when the regenerated nitrite ester is methyl nitrite, ethyl nitrite, n-propyl nitrite, or i-propyl nitrite, it does not form an azeotropic composition with water as a by-product during the regeneration reaction. Since the regeneration gas does not contain water, it can be circulated and supplied to the reactor as is.

The liquid discharged from the regeneration tower is an alcohol solution containing water produced as a by-product in the regeneration reaction. This is used as the alcohol source in the third step, and in some cases in the second step, after the alcohol is purified to a water content of 5% by volume or less, preferably 2% by volume or less, by distillation, extraction, or other operations. May be reused as an alcohol source.

4th Step The condensate containing the oxalic acid diester in the 2nd step and hydrogen are introduced into a reactor filled with a hydrogenation catalyst and brought into a contact reaction in the gas phase.

A fixed bed or a fluidized bed is effective as the reaction vessel, and the contact time between the hydrogenation catalyst and the raw material gas is preferably set to 5 seconds or less, preferably 0.2 to 2 seconds.

Known hydrogenation catalysts are used, such as copper chromite, copper zinc chromite, barium chromite, copper ammonium chromate, zinc chromate, Raney nickel, manganese chromite, magnesium chromite, etc. Can be mentioned. These can be used alone, but for example activated carbon,
Alumina, silica, diatomaceous earth, pumice, zeolite,
It may be used by supporting it on an inert carrier such as molecular sheep.

Hydrogen should generally be used in excess of the stoichiometric amount needed to convert the oxalate diester to ethylene glycol and the alcohol corresponding to the ester residue of the ester of the oxalate diester.

The reaction temperature is usually 150 to 300°C, preferably
The temperature is 180-230℃. Further, the reaction pressure is at least atmospheric pressure, preferably 10 to 40 kg/cm ² G.

The reaction product in this process is mostly alcohol corresponding to the ester residue of ethylene glycol and oxalic acid diester, but it also contains a small amount of glycolic acid ester in which only one ester of oxalic acid diester is hydrogenated. ing.

5th and 6th steps The product in the 4th step is led to a distillation column and distilled using normal operations to distill off the alcohol corresponding to the ester residue of the oxalic acid diester, and the target product, ethylene glycol, is removed from the distillation residue. Obtained as a liquid.

The distilled alcohol is recycled and supplied as part of the alcohol source to the regeneration tower in the third step. In addition, in the second step, when the non-condensable gas is condensed while being brought into contact with alcohol, it can also be circulated and supplied as part of the alcohol source.

In addition to the target product ethylene glycol, the distillation residual liquid contains a small amount of glycolic acid ester, but purified ethylene glycol can be obtained by distilling this liquid and distilling off the glycolic acid ester. can. Note that the glycolic acid ester is hydrogenated under the hydrogenation conditions in the fourth step.
Since it is hydrogenated to ethylene glycol like the oxalic acid diester, the distilled glycolic acid ester can also be recycled and supplied to the fourth step.

Next, the process of this invention will be specifically explained according to a flow sheet drawing showing one embodiment of this invention. In addition, in the figure, 1 and 5 are reactors, 2 and 7
3 is a condenser, 3 is a regeneration column, 8 and 9 are distillation columns, 4 is a heater, 5 is a heat exchanger, and 20 to 45 are conduits.

In a reactor 1 filled with a platinum group metal solid catalyst,
Carbon monoxide from the conduit 20 and gas containing nitrite, nitrogen monoxide, etc. from the conduit 21 are pressurized by a gas circulator (not shown) and transferred to the conduit 22.
introduced through. A catalytic reaction is carried out in the gas phase in the reactor 1, and the reaction product gas that has passed through the catalyst layer is taken out from the lower part and introduced into the condenser 2 through the conduit 23.

In the condenser 2, the reaction product gas is condensed while being brought into contact with alcohol introduced from the conduit 25 if necessary, and the condensed liquid mainly containing oxalic acid diester is led out through the conduit 30. On the other hand, non-condensable gases including unreacted carbon monoxide and nitrite ester, and by-product nitrogen monoxide,
It is introduced into the lower part of the regeneration tower 3 through a conduit 24.

In the regeneration tower 3, the non-condensable gas is passed through a conduit 2 at the bottom.
The molecular oxygen-containing gas introduced through 7 and the alcohol introduced at the top through conduit 28 are reacted in countercurrent contact to form nitrite esters. In this regeneration tower 3, following the oxidation reaction of nitrogen monoxide to nitrogen dioxide, an absorption reaction of the nitrogen monoxide to alcohol takes place. Note that if there is insufficient nitrogen source to produce nitrite ester, nitrogen oxides may be mixed in through the conduit 26.

The nitrite-containing gas generated in the regeneration tower 3 is circulated and supplied to the reactor 1 through conduits 21 and 22 together with carbon monoxide newly supplied from the conduit 20. On the other hand, water produced as a by-product in the regeneration tower 3 is taken out from the bottom through a conduit 29 in the form of an aqueous alcohol solution. This alcohol aqueous solution may be reused as an alcohol source to be supplied to the regeneration tower 3 or condenser 2 through the conduit 28 or 25 after removing water in the liquid by an operation such as distillation.

The oxalic acid diester-containing condensate in the condenser 2 is passed through conduit 30, where it is optionally mixed with the glycolic ester from conduit 44, and after being boosted to the desired pressure by a boost pump (not shown), it is passed through conduit 31 to the heater. 4 and contacted with hydrogen from conduit 32. The resulting gaseous mixture is introduced through conduit 33 into reactor 5 filled with hydrogenation catalyst;
Catalytic reactions are carried out in the gas phase. The reaction product gas is passed through the conduit 34
After being taken out through the heat exchanger 6 and cooled,
It is led to the condenser 7 through a conduit 35.

In the condenser 7, the reaction product gas is condensed, and the condensed liquid containing ethylene glycol as a main component is sent to the conduit 38.
It is led to the distillation column 8 through the distillation column 8. On the other hand, non-condensable gas containing hydrogen as a main component is taken out through a conduit 36, boosted to a desired pressure by a boost pump (not shown), heated by a heat exchanger 6, and passed through a conduit 37 to a conduit 3.
It is mixed with hydrogen from 2 and led to heater 4.

In the distillation column 8, alcohol is distilled off through a conduit 39, and this alcohol is recycled as an alcohol source to be supplied to the regeneration column 3 through conduits 40, 41 and conduit 28. A portion of this alcohol may also be transferred to conduit 42 and conduit 25 as the case may be.
It can also be reused as an alcohol source to be supplied to the condenser 2 through. The distillation residue is transferred to conduit 4
3 and led to a distillation column 9.

The by-product glycolic acid ester distilled in the distillation column 9 may be passed through a conduit 44 and optionally mixed with the oxalic acid diester from the conduit 30, and then led to the heater 4 through the conduit 31. On the other hand, the target ethylene glycol, which is the distillation residue, is obtained through the conduit 45.

Next, the present invention will be specifically explained using examples.

Example 1 Inside the tubes of a stainless steel multi-tube reactor A consisting of six tubes with an inner diameter of 36.7 mm and a height of 550 mm,
3 kg (3 kg) of pellet-shaped γ-alumina catalyst with a diameter of 5 mm and a height of 3 mm supporting 0.5% by weight of palladium.
) was filled.

A mixed gas (pressure: 0.2 Kg/cm ² G, composition:
carbon monoxide 22.0% by volume, methyl nitrite 9.1% by volume, nitrogen monoxide 3.1% by volume, methanol 9.4% by volume, carbon dioxide 8.5% by volume and nitrogen 47.0% by volume)
12.0Nm ³ / after preheating to approximately 90℃ using a heat exchanger.
hr and the temperature of the catalyst layer was maintained at 104-117°C by passing hot water through the shell side of the reactor.

The gas that has passed through the catalyst layer is
Methanol is introduced into the bottom of a 1400 mm Raschig ring packed gas-liquid contact condenser A, and methanol is pumped from the top of the column at a rate of 5.6/hr.
countercurrent contact was carried out at a rate of approximately 35°C (tower top temperature: 30°C, tower bottom temperature: 40°C). 2.8 kg/hr of condensate (composition: 46.6% by weight of dimethyl oxalate, 4.9% by weight of dimethyl carbonate, 0.03% by weight of methyl formate and 48.0% by weight of methanol) was obtained from the bottom of the column, while non-condensable gas (composition: 1% by weight) was obtained from the top of the column. Carbon oxide 15.4% by volume, methyl nitrite 3.9% by volume, nitrogen monoxide 6.8% by volume, methanol 24.2% by volume, oxygen supply gas 7.6% by volume and nitrogen 41.4% by volume) 13.6Nm ³ /hr were obtained.

After mixing 140/hr of oxygen and 9/hr of nitrogen monoxide into this non-condensable gas (molar ratio of oxygen to nitrogen monoxide in the gas = 0.15), the inner diameter was 158 mm, the height was
Methanol is introduced into the bottom of a 1400 mm gas-liquid contact type regeneration tower, and methanol (including methanol circulated in the regeneration tower) is fed from the top of the tower.
40/hr (of which 2.2/hr is distillation column A described later)
It was supplied from. ) at a rate of
Countercurrent contact was carried out at approximately 35°C (tower top temperature: 30°C, tower bottom temperature: 40°C), and nitrogen monoxide in the gas was regenerated into methyl nitrite. Regeneration gas in the regeneration tower (composition: carbon monoxide 15.4% by volume, methyl nitrite 8.0% by volume, nitrogen monoxide 2.8% by volume, methanol 24.2% by volume, carbon dioxide 7.6% by volume and nitrogen 41.3% by volume) 13.6Nm ³ /
After mixing 550/hr of carbon monoxide, the gas was compressed and supplied to the gas circulation pump, and the discharged gas was cooled to 20° C. to separate condensed methanol and led to reactor A.
On the other hand, 1.4/hr of an aqueous methanol solution containing 20.0% by weight of water was discharged from this regeneration tower and, after water was removed by distillation, was reused as a methanol source in the tower.

2.8Kg/hr of condensate drawn out from the condenser A
and methyl glycolate in distillation column B described later.
After mixing 0.05Kg/hr and increasing the pressure to 30Kg/cm ² G,
A gas consisting of 74.0% by volume of hydrogen and 25.2% by volume of nitrogen at the same pressure was mixed at 29.8Nm ³ /hr and heated to about 200°C. The resulting mixed gas is
mm reactor B (manufactured by Sakai Chemical Co., Ltd., Cu-Cr-Ba system ST-
203 catalyst 3.0 filling).

The gas that has passed through the catalyst layer is
It was led to a 1500 mm condenser B and cooled to about 40° C., and 2.85 kg/hr of condensate (composition: 22.8% by weight of ethylene glycol, 75.4% by weight of methanol, and 1.7% by weight of methyl glycolate) was obtained from the bottom of the column. On the other hand, 28.6 Nm ³ /hr of non-condensable gas (composition: hydrogen 73.8% by volume, nitrogen 26.2% by volume) led out from the top of the column was circulated and supplied as the hydrogen source.

The condensate 2.85Kg/hr obtained from condenser B was
mm, led to distillation column A with a height of 3000 mm, and the top temperature was 65 mm.
Distilled at a bottom temperature of 158°C. 2.7/hr of methanol distilled from the top of the column was circulated and supplied to the regeneration column and condenser A. On the other hand, the distillation residue obtained from the bottom of the column (composition: ethylene glycol 91.6% by weight,
Methyl glycolate 7.0% by weight) 0.71Kg/hr,
The mixture was introduced into a distillation column B having an inner diameter of 30 mm and a height of 3000 mm, and distillation was carried out at a top temperature of 95°C and a bottom temperature of 158°C. Methyl glycolate (0.05 kg/hr) distilled from the top of the column is circulated and supplied to the reactor B, while 0.70 kg/hr of ethylene glycol with a purity of 98.5% by weight is fed from the bottom of the column as a distillation residue.
Kg/hr was obtained.

Example 2 Inside the tubes of a stainless steel multi-tube reactor A consisting of six tubes with an inner diameter of 36.7 mm and a height of 550 mm,
2.5 kg (2.5
) was filled.

A mixed gas (composition: carbon monoxide 20.0% by volume, methyl nitrite) of carbon monoxide compressed to a pressure of 1.8 kg/cm ² G and the regeneration gas in the regeneration tower (described later) is passed through the catalyst bed from above using a diaphragm gas circulation pump.
15.1% by volume, 3.1% by volume of nitric oxide, methanol
13.2% by volume, 2.0% by volume of carbon dioxide and 46.9% by volume of nitrogen) was preheated to approximately 90°C in a heat exchanger.
By supplying hot water at a rate of 5.4Nm ³ /hr and passing hot water through the shell side of the reactor, the temperature of the catalyst layer is maintained at approximately 110℃.
was held at

The gas that has passed through the catalyst layer is
Methanol is introduced into the bottom of a 1400 mm Raschig ring packed gas-liquid contact condenser A, and methanol is pumped from the top of the column at a rate of 1.3/hr.
countercurrent contact was carried out at a tower top temperature of 40°C and a tower bottom temperature of 43°C. Condensate from the bottom of the tower (composition: dimethyl oxalate 48.0% by weight, dimethyl carbonate 1.5% by weight,
Methyl formate 0.3% by weight and methanol 48.0% by weight) 2.2Kg/hr were obtained, while non-condensable gas (composition: carbon monoxide 13.3% by volume, methyl nitrite 7.4% by volume) was obtained from the top of the column.
% by volume, nitric oxide 11.9% by volume, methanol 14.2
% by volume, 2.4% by volume of carbon dioxide and 50.9% by volume of nitrogen) 5.0 Nm ³ /hr was obtained.

After mixing 104.0/hr of oxygen into this non-condensable gas (molar ratio of oxygen to nitrogen monoxide in the mixed gas = 0.18), it is guided to the bottom of a gas-liquid contact type regeneration tower with an inner diameter of 158 mm and a height of 1400 mm. methanol from the top of the tower
The gas was introduced at a rate of 5.0/hr (of which 2.0/hr was supplied from distillation column A described later), and was brought into countercurrent contact at a tower top temperature of 40°C and a tower bottom temperature of 42°C. Nitric oxide was regenerated into methyl nitrite. Regeneration gas in the regeneration tower (composition: carbon monoxide 13.0% by volume, methyl nitrite 16.3% by volume, nitrogen monoxide 3.4% by volume, methanol 14.7% by volume, carbon dioxide 2.3% by volume and nitrogen 50.0% by volume) 5.1Nm ³ /hr was supplied to the gas circulation pump and compressed. Then the discharge gas
4.7Nm ³ /hr, carbon monoxide 66.8% by volume, methyl nitrite 6.3% by volume, methanol 1.3% by volume, nitrogen 25.6%
A mixed gas containing % by volume of 0.7 Nm ³ /hr was mixed and introduced into reactor A. On the other hand, 94.5% methanol aqueous solution derived from this regeneration tower 4.15/hr
was reused as the methanol source in the column after removing water by distillation.

2.2Kg/hr of condensate drawn out from the condenser A
and methyl glycolate in distillation column B described later.
After mixing 72.5g/hr and increasing the pressure to 30Kg/cm ² G,
A gas of 10.0 Nm ³ /hr consisting of 83.2% by volume of hydrogen and 14.0% by volume of nitrogen at the same pressure was mixed and heated to about 200°C. The resulting mixed gas is
mm reactor B (manufactured by Sakai Chemical Co., Ltd., Cu-Cr-Ba system ST-
203 catalyst (3.0 filling).

The gas that has passed through the catalyst layer is
It was led to a 1500 mm condenser B and cooled to about 40° C., and 2.3 kg/hr of condensate (composition: 23.1% by weight of ethylene glycol, 72.5% by weight of methanol and 3.2% by weight of methyl glycolate) was obtained from the bottom of the column. On the other hand, 9.2 Nm ³ /hr of non-condensable gas (composition: hydrogen 83.7% by volume, nitrogen 15.5% by volume) led out from the top of the column was circulated and supplied as the hydrogen source.

The condensate 2.3Kg/hr obtained from condenser B was
mm, led to distillation column A with a height of 3000 mm, and the top temperature was 65 mm.
Distilled at a bottom temperature of 158°C. 2.0/hr of methanol distilled from the top of the column was circulated and supplied to the regeneration column. On the other hand, the distillation residue obtained from the bottom of the column (composition:
84.7% by weight of ethylene glycol, 12.2% by weight of methyl glycolate) 0.59Kg/hr, inner diameter 30mm, height
The mixture was introduced into a 3000 mm distillation column B, and distilled at a top temperature of 95°C and a bottom temperature of 158°C. 72.5 g/hr of methyl glycolate distilled from the top of the column was circulated and supplied to the reactor B, while 0.51 kg/hr of ethylene glycol with a purity of 98.1% by weight was obtained as a distillation residue from the bottom of the column.

[Brief explanation of the drawing]

The figure shows a blow sheet showing an example of an embodiment of the present invention, in which 1 and 5 are reactors, 2 and 7 are condensers,
3 is a regeneration column, 8 and 9 are distillation columns, 4 is a heater, and 6 is a heat exchanger.

Claims (1)

[Claims] 1. Carbon monoxide and nitrite ester-containing gas,
A first step of contacting a platinum group metal-based solid catalyst in the gas phase to obtain a product containing an oxalic acid diester; A second step of separating the contained non-condensable gas and a condensate containing the oxalic acid diester; A third step in which the containing gas is circulated and supplied to the first step; 4. The condensate containing the oxalic acid diester in the second step is brought into contact with hydrogen in a gas phase to a hydrogenation catalyst to form a product containing ethylene glycol. 5 A fifth step in which the product in the fourth step is distilled to distill off the alcohol to obtain ethylene glycol; 6 A fourth step in which the alcohol in the fifth step is circulated and supplied as an alcohol source to the third step. It is characterized by consisting of six steps. Continuous production of ethylene glycol.