JPH10152450A - Production of butanediol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing highly pure butanediol useful as a raw material for a polyester resin, etc., by performing acetoxylation of butadiene used as a raw material, further hydrogenating the product to provide diacetoxybutane and hydrating the diacetoxybutane. SOLUTION: This method for producing butanediol is performed by reducing the content of diacetoxyoctane of <=0.5wt.%, and the reduction of the content is preferably performed by distilling and removing the one because the process is simplified. The acetoxylation is performed at 40-180 deg.C, preferably 60-150 deg.C at a pressure over a normal pressure, and normally <=300kg/cm<2> . The hydrogenation reaction is performed at 40-180 deg.C at a pressure equal to or over a normal pressure and normally <=150kg/cm<2> in the presence of a catalyst such as Pd. The amount of hydrogen is usually 1-50 mol per mol diacetoxybuytene and the hydration reaction is performed in the presence of a solid acid catalyst by using 2-100 mol water per mol diacetoxybutane at 30-110 deg.C usually under a pressure between a normal pressure and 10kg/cm<2> G.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing high-purity butanediol. More specifically, the present invention relates to an improvement in a method for producing butanediol by hydrolyzing diacetoxybutane obtained by acetoxylation and hydrogenation of butadiene. Butanediol is a compound useful as a solvent or a synthetic material such as a polyester resin, γ-butyrolactone, and tetrahydrofuran.

[0002]

2. Description of the Related Art As a method for producing butanediol, butadiene, acetic acid and oxygen are reacted in the presence of a palladium-based catalyst to obtain diacetoxybutene, and then a palladium-based or nickel-based catalyst is used. A method is known in which diacetoxybutane obtained by hydrogenation reaction is hydrolyzed into butanediol (see, for example,
2-7909, 52-133912, JP-A-7-82
No. 191).

In this method using butadiene as a raw material, a large amount of acetic acid is used in the acetoxylation step of butadiene,
It is necessary to remove unreacted acetic acid and by-produced water, and a large amount of water is used in the hydrolysis process of diacetoxybutane.
Because it is necessary to remove unreacted water and acetic acid produced as a by-product,
Various proposals have been made to collect and recycle these while maintaining product purity (see the above publications).
On the other hand, for the use of butanediol, particularly for polyester resin raw materials, and for tetrahydrofuran used as a polyether raw material such as polytetramethylene ether glycol, the purity of butanediol depends on the speed of the polymerization reaction and the molecular weight of the obtained polymer. Therefore, high-purity butanediol that does not affect the polymerization reaction is required.

[0004]

In the above-mentioned method, the reaction product obtained by hydrolyzing diacetoxybutane is subjected to distillation, and usually, the bottom of the column obtained by distilling off water, acetic acid and other light boilers is removed. A component containing butanediol is obtained as a liquid, and the bottoms are further distilled to distill, for example, light boiling components from the top, diacetoxybutane, hydroxyacetoxybutane, etc. High-purity butanediol is obtained by rectifying butanediol distilled from a stream or the bottom of the column, but this method does not always sufficiently remove impurities. The present invention uses butadiene as a raw material,
To provide a method for industrially and advantageously producing high-purity butanediol suitable for use as a polyester resin raw material, a tetrahydrofuran raw material, or the like, by acetoxylating this and then hydrolyzing diacetoxybutane obtained by hydrogenation. With the goal.

[0005]

Means for Solving the Problems As a result of intensive studies on a method for producing high-purity butanediol, the present inventors have found that butanediol obtained from butadiene contains impurities which are difficult to separate by distillation. The impurity that is difficult to separate is monoacetoxyoctanol, and the boiling point of monoacetoxyoctanol is estimated to be about 270 ° C. From the measurement results of the vapor-liquid equilibrium, it is found that 1,4-butanediol (boiling point 230 ° C) It was found that separation by distillation was more difficult than expected from the boiling point difference of about 40 ° C., and that the impurity monoacetoxyoctanol was formed by hydrolysis of diacetoxyoctane contained in diacetoxybutane. The present invention has been completed.

That is, the present invention relates to a method for producing butanediol by hydrolyzing diacetoxybutane, wherein the content of diacetoxyoctane in the diacetoxybutane subjected to the hydrolysis reaction is 0.5% by weight or less. An object of the present invention is to provide a method for producing butanediol, which is characterized in that: By adjusting the content of diacetoxyoctane to 0.5% by weight or less, preferably 0.01 to 0.2% by weight, the hydrolysis reaction product is subjected to distillation according to a conventional method, and water and acetic acid and other light The bottoms bottoms from which the boiled substances have been distilled off are distilled to distill the butanediol fraction from which the light boiling point has been distilled off, whereby the content of the impurity monoacetoxyoctanol is 1% by weight or less, that is, the purity is 99%. High purity 1,4% by weight or more
-Butanediol can be obtained.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As a method for reducing the content of diacetoxyoctane in diacetoxybutane to 0.5% by weight or less, a diacetoxybutane obtained by distilling and recovering diacetoxybutene from an acetoxylation reaction product is used. A method of reducing the amount of diacetoxyoctadiene in acetoxybutene to a predetermined amount (0.5% by weight) or less, and diacetoxyoctane in diacetoxybutane which is a hydrogenation reaction product obtained by hydrogenating diacetoxybutene. The total amount of diacetoxyoctane in diacetoxybutane is reduced to 0 by combining the method of removing by distillation to 0.5% by weight or less and the method of reducing the corresponding impurities in each of the above steps, in whole or in part. A method of adjusting the content to 0.5% by weight or less can be appropriately adopted. From the viewpoint of energy load of the entire process and simplification of the process, a method of distilling and removing diacetoxyoctadiene is preferable.

Hereinafter, an example of a production process for obtaining diacetoxybutene from butadiene as a raw material by an acetoxylation reaction and subjecting it to a hydrogenation reaction and a hydrolysis reaction to form butanediol will be described with reference to the drawings. In FIG. 1, 1 is an acetoxylation reactor, 2 is a first distillation column, 3 is a second distillation column, 4 is a hydrogenation reactor, 5 is a third distillation column, 6 is a hydrolysis reactor, and 7 is a fourth reactor. A distillation column, 8 is a fifth distillation column, and 9 is a sixth distillation column.

(1) Acetoxylation reaction step of reacting butadiene with acetic acid and molecular oxygen to obtain diacetoxybutene: In the acetoxylation reaction, butadiene, acetic acid, and molecular oxygen are converted in the presence of a palladium-based catalyst. The reaction is carried out by a known method for causing a reaction in the reactor (1). As the palladium-based catalyst, palladium metal or a salt thereof (for example, an organic or inorganic acid salt such as palladium chloride, palladium nitrate, and palladium acetate) alone or as a co-catalyst such as bismuth, selenium, antimony, tellurium, and copper is used. Metals or their salts, acids, and oxides (for example, bismuth oxide, selenic acid, tellurium oxide, antimony chloride, orthotelluric acid, copper chloride, and the like) are used in combination. The catalyst is preferably used by being supported on a carrier such as silica, alumina or activated carbon. The amount of the catalyst metal in the supported catalyst is usually 0.1 to 20% by weight of palladium metal, and another promoter metal is used. In this case, the metal is 0.01 to 30% by weight.
Is selected in the range.

The acetoxylation reaction is carried out by a known fixed bed method,
It is carried out by any method such as a fluidized bed system and a catalyst suspension system. The reaction is carried out at 40 to 180 ° C, preferably at 60 to 150 ° C.
Above normal pressure, usually 300 kg / cm
² [29.4 MPa] or less, preferably 30 to 150 k
It is carried out under a pressure of g / cm ² [2.94 to 14.7 MPa]. Since the reaction product of acetoxylation thus obtained contains unreacted butadiene and the like, it is general to obtain diacetoxybutene after degassing and distillation.

The distillation is usually carried out in a first distillation column (2) using water,
Acetic acid is distilled off from the top of the column, and the bottom liquid is removed from the second distillation column (3).
And diacetoxybutene is obtained from the top of the column, and a high-boiling substance containing diacetoxyoctadiene is withdrawn from the bottom of the column. At this time, the bottom liquid of the second distillation column (3) is supplied to a thin-film evaporator to increase the efficiency of separation from high-boiling substances (for details, see Japanese Patent Application Laid-Open No.
321861).

The amount of diacetoxyoctadiene contained in the diacetoxybutene recovered from the top is determined by the amount of diacetoxyoctadiene in the diacetoxybutene supplied to the second distillation column (3) and the amount of diacetoxyoctadiene in the second distillation column. Usually, the amount of diacetoxyoctadiene in diacetoxybutene supplied to the second distillation column (3) is about 3% by weight, which is determined by the operating conditions of the column. The second distillation column (3) has a theoretical plate of 5
In 10 to 10 stages, the top pressure is 5 to 200 mmHg (0.7 to 2
6.7 kPa), tower bottom temperature 190 ° C. or less, reflux ratio 0.1
1, operating at a distillation rate of 70 to 99% from the top.

The amount of diacetoxyoctadiene in diacetoxybutene withdrawn from the top of the second distillation column under the above operating conditions is about 0.1 to 2.5% by weight. When combined with the method of removing diacetoxyoctane by distillation, the distillation conditions are set so as to be 1.0 to 2.5% by weight, preferably 1.5% by weight or less, and only diacetoxyoctadiene is removed by distillation. In this case, the distillation conditions are set so as to be 0.5% by weight or less, preferably 0.1% by weight or less. In order to improve the removal of impurities in diacetoxybutene, a method of increasing the number of theoretical plates or the reflux ratio and narrowing the distilling rate under distillation conditions is usually employed. The distillation column
The operation is carried out at 5 to 20 theoretical stages, with a reflux ratio of 0.1 to 10 and a distillate rate of 70 to 97% from the top.

(2) Hydrogenation step of hydrogenating the reaction product obtained in the acetoxylation reaction step to obtain diacetoxybutane: Diacetoxybutene obtained from the top of the second distillation column (3) is then It is subjected to a hydrogenation reaction to produce diacetoxybutane. The hydrogenation reaction is usually carried out by contacting acetoxybutene with hydrogen in the reactor (4) in the presence of a noble metal catalyst such as palladium or ruthenium or a nickel catalyst, and
In a temperature range of 180 ° C., normal pressure or higher, usually 150 kg /
It is carried out by reacting under a pressure up to cm ² [14.7 MPa].

The hydrogenation reaction is carried out by any known method such as a fixed bed system, a fluidized bed system and a catalyst suspension system. The hydrogen used in the hydrogenation reaction may be not only high-purity hydrogen but also hydrogen diluted with another gas that does not adversely affect the reaction. The amount used is usually 1 to 50 mol, preferably 2 to 20 mol, per 1 mol of diacetoxybutene.

The hydrogenated reaction product is subjected to degassing of unreacted hydrogen and then distilled in a third distillation column (5) to obtain diacetoxybutane. In the distillation, diacetoxybutane is generally distilled from the top of the column, and a high-boiling product containing diacetoxyoctane, which is a hydride of diacetoxyoctadiene, is removed from the bottom of the column. The third distillation column (5) has 5 to 10 theoretical plates and a top pressure of 5 to 200 mmHg [0.7 to 26.7 kPa];
The operation is performed at a bottom temperature of 190 ° C. or lower, a reflux ratio of 0.1 to 1, and a distilling rate of 70 to 99% from the top of the column.

The amount of diacetoxyoctane in diacetoxybutane supplied to the third distillation column (5) is determined by the operating conditions of the second distillation column (3). When the diacetoxyoctadiene is removed to 0.5% by weight or less in the second distillation column, the content is 0.5% by weight or less, preferably 0.1% by weight or less. Diacetoxyoctadiene in the tower
When it is 2.5% by weight, preferably 1.5% by weight or less, it is 1.0 to 2.5% by weight, preferably 1.5% by weight or less. If the diacetoxyoctadiene is not sufficiently distilled off in the second distillation column and exceeds 2.5% by weight, the diacetoxyoctane in the diacetoxybutane supplied to the third distillation column exceeds 2.5% by weight, Depending on the distillation conditions of the third distillation column, diacetoxyoctadiene needs to be 0.5% by weight or less.

When the removal of diacetoxyoctadiene in the second distillation column and the removal of diacetoxyoctane in the third distillation column are combined, the relationship between the removal amounts of the two distillation columns depends on the distillation load of each column. Although appropriately set, it is preferable that the removal ratio of diacetoxyoctadiene in the second distillation column is 50% or more of the predetermined removal amount. The amount of diacetoxyoctane in diacetoxybutane withdrawn from the top is 1.0 when the second distillation column is under normal operating conditions.
To 2.5% by weight, and 0.5% by weight in the method of the present invention.
Hereinafter, the conditions of the third distillation column are set so as to be preferably 0.2% by weight or less. Specifically, the third distillation column (5)
Is operated in 5 to 20 theoretical stages, with a reflux ratio of 0.1 to 10 and a distillate rate of 70 to 97% from the top of the column. When the content of diacetoxyoctane exceeds 0.5 weight, it is contained as monoacetoxyoctanol in butanediol obtained by hydrolyzing it, and it is difficult to remove it by distillation.

(3) Step of hydrolyzing the hydrogenation reaction product to obtain butanediol: The hydrolysis reaction is usually carried out in a reactor (6) in the presence of a solid acid catalyst such as a cation exchange resin. Contacting diacetoxybutane and water, 30-110
C., preferably in a temperature range of 40 to 90.degree. C., under such a pressure as to prevent a boiling state from occurring or to generate remarkable gas bubbles due to a dissolved gas during the reaction.
It is performed in the range of 0 kg / cm ² G [0.098 to 1.08 MPa]. The amount of water used for the reaction is usually 2 to 100 mol, preferably 4 to 50 mol, based on 1 mol of diacetoxybutane. When the amount of water is too small, the reaction rate decreases, while If the amount is too large, a large amount of heat energy is required to recover butanediol from the reaction product, which is not preferable.

The reaction is carried out by any method such as a batch system and a continuous system. When the ion exchange resin is used, the reaction may be carried out in a suspended state, or the reaction raw material may be passed through a packed bed of the ion exchange resin. The fixed bed continuous method is industrially advantageous. When the reaction is carried out in a suspension bed, the amount of the ion exchange resin used is 0.1 to 50% by weight, preferably 1 to 10% by weight, based on the weight of the liquid. In the case of the fixed bed continuous method, water and diacetoxybutane are continuously supplied to the ion-exchange resin packed bed reactor maintained at a predetermined temperature, and the produced butanediol and acetic acid are mixed as an excess water. It is performed by extracting continuously.

Diacetoxybutane and water reactor (6)
The components may be supplied separately or in a mixture, or may be supplied in a uniform liquid phase in the presence of butanediol or monohydroxyacetoxybutane as a reaction product. In the case of a fixed bed, it is preferable to supply a uniform liquid phase in order to smoothly promote the reaction. The reaction product liquid contains acetic acid and water, a partial hydrolysis product, some by-product tetrahydrofuran, and the like, in addition to the intended butanediol. After completion of the reaction, the catalyst is filtered off from the reaction solution, if necessary, and distilled to obtain butanediol. In the distillation, usually, water and acetic acid are distilled off from the top in a fourth distillation column (7), and the bottom liquid is supplied to a fifth distillation column (8), and unreacted diacetoxybutane is supplied from the top. And isomers,
The bottom liquid mainly containing 4-butanediol is supplied to the sixth distillation column (9), and the desired product 1,4-
Butanediol is obtained and high boilers are removed from the bottom of the column. The amount of monoacetoxyoctanol in the product 1,4-butanediol is less than 1% by weight, preferably 0-0.5% by weight.

[0022]

The present invention will be described more specifically with reference to the following experimental examples. In the examples, “parts” means “parts by weight”.
And “%” means “% by weight”. (Reference Example 1) Acetoxylation reaction In an acetoxylation reactor, 1,3-butadiene 170 parts /
hr, acetic acid 3000 parts / hr, and oxygen 530 parts / hr
And reacted at 9 MPa and 100 ° C. in the presence of a catalyst in which 3% of palladium and 0.6% of tellurium are supported on activated carbon, followed by degassing, and 14.2% of diacetoxybutene.
A reaction product containing 0.6% of diacetoxyoctadiene was obtained. The reaction product was fed to the first distillation column at 3100 parts / hr, most of water and acetic acid were distilled off at the top at 252 parts / hr, and diacetoxybutene 84.5%, diacetoxyoctadiene 3 Of the bottom liquid containing 0.2% by weight of 580 parts /
Canned at hr.

Example 1 The bottom liquid obtained in Reference Example 1 was used for the second step.
It is supplied at 580 parts / hr to a distillation column (actual number of plates is 20),
Distillation was performed under the conditions of a top pressure of 2.7 kPa and a reflux ratio of 0.5.
A liquid containing 86.3% of diacetoxybutene and 1.0% of diacetoxyoctadiene was distilled at 550 parts / hr from the top of the tower. The obtained diacetoxybutene fraction is supplied to a hydrogenation reactor filled with a palladium catalyst and a ruthenium catalyst, and a hydrogenation reaction is carried out at a reaction pressure of 5 MPa and a temperature of 70 ° C. under a hydrogen flow, and diacetoxybutane 86.5. % And diacetoxyoctane 1.0%. The reaction solution is
After the gas-liquid separation, 550 parts /
hr, an overhead pressure of 2.0 kPa and a reflux ratio of 0.2
Distilled under the conditions of 5 and diacetoxybutane from the top of the column.
A solution containing 1% and diacetoxyoctane 0.2% is 520
Parts / hr.

The obtained hydrogenated reaction solution was charged at 520 parts / hr.
The mixture was supplied to a hydrolysis reactor filled with a strongly acidic ion exchange resin (Diaion SK-1B; trade name of Mitsubishi Chemical Corporation) together with 500 parts of water / hr, and a hydrolysis reaction was performed at a temperature of 50 ° C. A reaction solution containing 10.2% of 4-butanediol and 0.04% of monoacetoxyoctanol was obtained. The reaction solution was supplied to the fourth distillation column at 1020 parts / hr, and most of water and acetic acid were distilled off at the top at 660 parts / hr,
A bottom liquid containing 28.9% of 1,4-butanediol and 0.1% of monoacetoxyoctanol was withdrawn at 360 parts / hr, and the bottom liquid was supplied to a fifth distillation column, and unreacted from the top of the column. After distilling diacetoxybutane and the like, the bottom product of the fifth distillation column is supplied to the sixth distillation column to remove high-boiling substances from the bottom of the column, and from the top of the column, 99.3% pure 1,9 is removed. 4-butanediol was obtained. The monoacetoxyoctanol concentration in 1,4-butanediol was 0.4%.

(Embodiment 2) In Embodiment 1, reference example 1
Distillation was carried out under the same conditions as in Example 1 except that the reflux ratio of the second distillation column to which the bottom liquid obtained in the above was supplied was set to 5, 87.1% of diacetoxybutene and 0.1% of diacetoxyoctadiene from the top of the column.
A distillate containing 1% was obtained. The obtained diacetoxybutene fraction was supplied to a hydrogenation reaction under the same conditions as in Example 1 to obtain a reaction solution containing 87.3% of diacetoxybutane and 0.1% of diacetoxyoctane.

After the obtained hydrogenated reaction solution is subjected to gas-liquid separation,
Without supplying to the distillation column, a hydrolysis reaction was directly carried out under the same conditions as in Example 1 to give 1,4-butanediol 10.4
%, And a reaction liquid containing 0.02% of monoacetoxyoctanol was obtained. The reaction solution was supplied to the fourth, fifth, and sixth distillation columns in the same manner as in Example 1, and from the top of the sixth distillation column, 1,4 with a purity of 99.5% was added. -Butanediol was obtained. Monoacetoxyoctanol concentration 0.2%
Met.

(Comparative Example 1) Distillation was carried out under the same conditions as in Example 1 except that the reflux ratio of the second distillation column was changed to 0.05, and 85.0% of diacetoxybutene was added from the top of the column. A distillate containing 1.7% of diacetoxyoctadiene was obtained.
The obtained diacetoxybutene fraction was supplied to a hydrogenation reaction in the same manner as in Example 2, and the obtained hydrogenation reaction solution (diacetoxybutane 85.1%, diacetoxyoctane 1.6%) Was not supplied to the third distillation column after gas-liquid separation, and the hydrolysis reaction was directly carried out under the same conditions as in Example 1 to obtain 9.9% of 1,4-butanediol and 0.3 of monoacetoxyoctanol. % Was obtained. The reaction solution was subjected to a fourth distillation tower, a fifth distillation tower,
And a sixth distillation column to obtain 1,4-butanediol having a purity of 95.1% from the top of the sixth distillation column. The monoacetoxyoctanol concentration was 3.2%.

[0028]

According to the present invention, as a raw material for polyester, tetrahydrofuran or the like having a content of monoacetoxyoctanol, which is an impurity difficult to separate by distillation contained in butanediol obtained by a butadiene method, being 1% by weight or less. High-purity 1,4-butanediol suitable for use can be industrially advantageously obtained.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing an example of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Acetoxylation reactor 2 1st distillation tower 3 2nd distillation tower 4 Hydrogenation reactor 5 3rd distillation tower 6 Hydrolysis reactor 7 4th distillation tower 8 5th distillation tower 9 6th distillation tower

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C07C 67/283 C07C 67/283 69/16 69/16 // C07B 61/00 300 C07B 61/00 300

Claims (8)

[Claims] 1. A method for producing butanediol by hydrolyzing diacetoxybutane, wherein the content of diacetoxyoctane in diacetoxybutane subjected to the hydrolysis reaction is 0.5% by weight or less. A method for producing butanediol, which is characterized by: 2. The method according to claim 1, wherein the diacetoxybutane is obtained by hydrogenating diacetoxybutene. 3. The method according to claim 1, wherein the diacetoxybutane is obtained by using butadiene as a raw material, acetoxylating this, and further hydrogenating it. 4. The method according to claim 3, wherein the acetoxylation of butadiene is obtained by reacting butadiene, acetic acid and molecular oxygen in the presence of a palladium-based catalyst to obtain diacetoxybutene. 5. A diacetoxyoctane content of 0.2
The production method according to claim 1, wherein the content is not more than% by weight. 6. The diacetoxybutene having a diacetoxyoctadiene content of 0.2% by weight or less.
The production method described in 1. 7. The method according to claim 1, wherein the butanediol is 1,4-butanediol. 8. The method according to claim 7, wherein the content of monoacetoxyoctanol in 1,4-butanediol is 1% by weight or less.