JPH11106359A - Production of butane diol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for industrially advantageously producing butane diol by reducing a using amount of vapor for separating water and acetic acid derived from hydrolysis in the production of butane diol by hydrolysis of diacetoxybutane. SOLUTION: This method for producing highly purified butane diol is performed by bringing diacetoxybutane into contact with water in the presence of a solid acid catalyst to hydrolyze, separating water and acetic acid from crude butane diol and purifying the crude butane diol. In the method, at least two combinations of a hydrolysis reaction process and subsequent separating process of water and acetic acid from the crude butane diol are repeated and a part of the water and acetic acid recovered from a hydrolysis reacted solution after the second stage process is extracted from the reaction system, then is used as a raw material water of a hydrolysis reaction in a pre-stage of the second hydrolysis reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing butanediol. More specifically, the present invention relates to an improvement in a method for producing butanediol by hydrolysis of diacetoxybutane. 1,4-Butanediol is a substance useful as a raw material of PBT resin and γ-butyrolactone, a raw material of an organic solvent, and tetrahydrofuran used as a raw material of polytetramethylene ether glycol (PTMG).

[0002]

2. Description of the Related Art A method for producing butanediol by hydrolyzing diacetoxybutane is disclosed in, for example, JP-A-52-7909. This method provides a method for producing butanediol by mixing butanediol and / or hydroxyacetate with a raw material diacetate and performing one-stage hydrolysis. Since the hydrolysis reaction is an equilibrium reaction, a large amount of water must be used to perform the hydrolysis in a single step, and therefore a large amount of energy is required to separate the product, which is economical. Not advantageous.

On the other hand, a countercurrent two-stage reaction has been disclosed as an efficient hydrolysis method (Japanese Patent Laid-Open No. 52-6 / 1982).
No. 5208). According to this method, the hydrolysis reaction can be carried out more efficiently with a smaller amount of raw water than the one-stage method described in the above publication. In this method, acetic acid is contained in the water recovered from the second reactor,
The inlet of the reactor has a uniform composition, and the unreacted raw materials and monoesters and the like recovered in the unreacted material recovery step are returned to the subsequent reactor, so that the reaction proceeds advantageously. I have.

[0004]

However, this method also requires a large amount of energy for separating water and acetic acid, and further improvement has been desired. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for performing a hydrolysis reaction of diacetoxybutane by reducing steam for separating water and acetic acid by hydrolysis of diacetoxybutane.

[0005]

Means for Solving the Problems As a result of intensive studies in view of the above circumstances, the present inventors have found that, when carrying out hydrolysis of diacetoxybutane using a plurality of reactors having a solid acid catalyst, When a mixture of water and acetic acid distilled and separated from the hydrolysis reaction solution is used as a raw material for the hydrolysis in the preceding step,
The present inventors have found that the object is achieved by supplying a part of the water to the acetic acid recovery step and using the remaining water as the raw material water for the hydrolysis reaction in the preceding step, thereby completing the present invention.

That is, the gist of the present invention is that diacetoxybutane is brought into contact with water in the presence of a solid acid catalyst to hydrolyze, then water, acetic acid and crude butanediol are separated, and then crude butanediol is separated. A method for producing high-purity butanediol by purification, comprising at least two combinations of a hydrolysis reaction step and a subsequent separation step of water, acetic acid and crude butanediol, and the second and subsequent hydrolysis steps Water recovered from the reaction solution, a method for producing butanediol, characterized in that after extracting a part of the acetic acid out of the system, it is used as raw water for the hydrolysis reaction preceding the hydrolysis reaction. It is in. Hereinafter, the present invention will be described in detail.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for producing 1,4-butanediol from butadiene as a raw material through an acetoxylation reaction, followed by hydrogenation and hydrolysis steps has been conventionally known. The acetoxylation reaction is performed by a known method of reacting butadiene, acetic acid, and molecular oxygen in the presence of a palladium-based catalyst.

As the palladium-based catalyst, palladium metal or a salt thereof is used alone, or bismuth,
It is used in combination with a metal such as selenium, antimony, tellurium, copper or a salt thereof. The catalyst is silica, alumina,
It is preferable to use the carrier supported on a carrier such as activated carbon. The acetoxylation reaction is usually performed in a temperature range of 40 to 180 ° C. under a pressure equal to or higher than normal pressure. The amount of acetic acid used is desirably used in a large excess also as a solvent, and is usually 5 to 60 mol, preferably 10 to 1 mol per conjugated diene.
４０40 mol.

The acetoxylation reaction is carried out by any known method such as a fixed bed system, a fluidized bed system, and a catalyst suspension system. From the reaction product, diacetoxybutene and other light boilers including water, acetic acid and monoacetoxybutene are separated by distillation. Water containing monoacetoxybutene,
The distillate containing acetic acid as a main component is sent to an acetic acid purification step.

[0010] Diacetoxybutene is separated from high boiling substances and then hydrogenated to give diacetoxybutane. The hydrogenation reaction is carried out by bringing diacetoxybutene into contact with hydrogen in the presence of a noble metal catalyst such as palladium or ruthenium, usually at 40 to
The reaction is carried out in a temperature range of 180 ° C. at a reaction pressure of normal pressure or higher. 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 produced diacetoxybutane is contacted with water in the presence of a solid acid catalyst and hydrolyzed to obtain butanediol. As the raw material diacetoxybutane used in the present invention, in addition to those mainly containing 1,4-diacetoxybutane, depending on the production and purification treatment steps,
Also included are isomer mixtures of 1,4-diacetoxybutane, 1,2-diacetoxybutane, 1,3-diacetoxybutane, and the like.

In some cases, the hydrolysis reaction is allowed to proceed to some extent, and then water and acetic acid are removed from 1,4-diacetoxybutane, 1,4-monohydroxyacetoxybutane and 1,4-butanediol. Mixtures are also available.
Examples of the solid acid catalyst used in the present invention include silica-alumina, activated earth, silica, and a cation exchange resin. However, since the cation exchange resin has a high hydrolysis rate and has few by-products such as tetrahydrofuran. preferable. As the cation exchange resin, a sulfonic acid type strongly acidic ion exchange resin having a copolymer of styrene and divinylbenzene as a base is suitable, and may be a gel type resin or a porous type resin. Specific examples thereof include SK1B, SK104, SK108, and PK20 manufactured by Mitsubishi Chemical Corporation.
8, PK216, PK228, and the like.

The hydrolysis reaction is usually carried out at 30 to 120 ° C.
It is preferably carried out at 40 to 100 ° C. If the temperature is too low, the reaction rate will be extremely slow, requiring a large amount of catalyst, while if the temperature is too high, side reactions to tetrahydrofuran, dihydrofuran, etc. will increase. The reaction pressure is not particularly limited, but a pressure that prevents a boiling state during the reaction or generation of remarkable bubbles due to a dissolved gas or the like is used.
It is in the range of 10 kg / cm ² G.

The ratio of diacetoxybutane to water is more than the stoichiometric amount, since water is a raw material and a solvent at the same time. In order to smoothly carry out the hydrolysis reaction, it is desirable to carry out the reaction in a homogeneous liquid phase. Acetoxybutane dissolves in a large amount of water to form a homogeneous liquid phase, and the larger the amount of water, the higher the conversion of the reaction. However, the cost of recovering a large amount of water is expensive and not economical. However, if the amount of water used is too small, the conversion of the reaction decreases. Therefore, the molar ratio of diacetoxybutane to water is usually in the range of 2 to 100, preferably 4 to 50.

[0015] The hydrolysis reaction is carried out by any method such as a batch system or a continuous system. When an ion exchange resin is used, a method in which the reaction is carried out in a suspended state or a method in which the reaction raw material is passed through a packed bed of the ion exchange resin may be used, and the fixed bed continuous method is industrially advantageous. Since the hydrolysis reaction is an equilibrium reaction, it is efficient and preferable to employ a multistage reaction system.

In the countercurrent multistage hydrolysis reaction, diacetoxybutane as a raw material is supplied to the first reactor, and raw water is supplied to the last reactor. For example, in the three-stage hydrolysis reaction shown in FIG. 1, diacetoxybutane is supplied to a first hydrolysis reactor, and raw water is supplied to a third hydrolysis reactor. The reaction liquid flowing out of each reactor is distilled at normal pressure or reduced pressure in a water, acetic acid separation tower following each reactor,
Water and acetic acid are distilled from the top of the column, and a hydrolysis product is obtained from the bottom of the column. Water, acetic acid (water:
(20 to 70% by weight / acetic acid: 80 to 30% by weight) is sent to an acetic acid recovery step to recover acetic acid. Water and acetic acid (water: 30 to 90% by weight / acetic acid: 7) separated in the second aqueous acetic acid separation tower
0 to 10% by weight) and water and acetic acid ((water: 50 to 95% by weight / acetic acid: 50 to 5% by weight)) separated in the third water acetic acid separation tower are used as raw water for the hydrolysis in the first stage. The hydrolysis products obtained from the bottoms of the first and second aqueous acetic acid separation towers are sent to the next hydrolysis reactor for further hydrolysis.
The product obtained from the bottom of the third water acetic acid separation tower is sent to the unreacted material recovery tower, and after separating the unreacted material and 1,4-butanediol, the unreacted material is subjected to the hydrolysis step. It is recycled or partly supplied to the THF conversion step as a raw material for THF.

The first aqueous acetic acid separation column usually has 3 to 15 theoretical plates and a top pressure of 50 Torr to a normal pressure (6.67 to
101.3 kPa), operating at a bottom temperature of 100 to 250 ° C. and a reflux ratio of 0.01 to 5.0, the second water acetic acid separation column is
Usually, the number of theoretical plates is 3 to 15, the top pressure is 50 Torr to normal pressure (6.67 to 101.3 kPa), the bottom temperature is 100 to
Operating at 250 ° C. and a reflux ratio of 0.01 to 5.0, the third aqueous acetic acid separation column usually has 3 to 15 theoretical plates and a top pressure of 5
The operation is performed at 0 Torr to normal pressure (6.67 to 101.3 kPa), a bottom temperature of 100 to 250 ° C., and a reflux ratio of 0.01 to 5.0.

[0018] Also in the countercurrent multistage hydrolysis, it is necessary to increase the amount of raw water to be supplied in order to increase the production amount of 1,4-butanediol. In such a case,
Unreacted water must be distilled in each distillation column, which increases the amount of steam used. In order to reduce the amount of steam without significantly affecting the hydrolysis reaction, analysis of the countercurrent multi-stage hydrolysis revealed that the final hydrolysis reaction governed the hydrolysis reaction results. It was also found that the hydrolysis reaction in the second stage was not significantly affected even if the amount of supplied water was reduced to some extent. This is because the hydrolysis reaction is equilibrium, and acetic acid is contained in the raw material water supplied to the first and second stage hydrolysis reactions. By not receiving it. The hydrolysis reaction proceeds more advantageously if an amount of new water corresponding to the water reduced in the first and second stage reactions is additionally supplied to the third stage hydrolysis reaction.

The amount of the water and acetic acid mixture extracted from the second water acetic acid separation column to the acetic acid recovery step is not preferable because an excessively large amount will affect the hydrolysis reaction. The amount of the water and acetic acid mixture extracted from the third water acetic acid separation column is preferably 40 to 60% by weight of the mixture distilled from the third water acetic acid separation column.
% By weight or less is preferred.

The concentration of acetic acid in the distillate of the second water acetic acid separation tower supplied to the first hydrolysis reactor is higher than the concentration of acetic acid in the distillate of the third water acetic acid separation tower. If the distillate sent from the third water acetic acid separation tower to the acetic acid recovery step is used as the raw water to be supplied to the acetic acid recovery step, and the distillate water sent from the second water acetic acid separation tower to the acetic acid recovery step is increased, the hydrolysis will more advantageously Can be implemented.

The crude butanediol thus obtained and obtained from the bottom of the third water acetic acid separation column is sent to the unreacted material recovery column and distilled. Crude butanediol is 1,2-diacetoxybutane (1,2 DAB), 1-hydroxy-
2-acetoxybutane (1,2HAB), 2-hydroxy-1-acetoxybutane (2,1HAB), 1,2-
Butanediol (1,2BG), 1,4-diacetoxybutane (1,4DAB), 1-hydroxy-4-acetoxybutane (1,4HAB), 1,4-butanediol (1,4BG), and the structure Contains unknown high boilers and some light boilers. The crude butanediol is distilled to obtain a fraction mainly composed of a light boiler, 1,2 DAB, 1,2 HAB, 2,1 HAB and 1,2BG, and 1,4 DA
B, a fraction mainly composed of 1,4HAB (fraction),
4BG and bottoms containing high boiling point.

Incidentally, the unreacted material recovery column usually has 80 to 110 theoretical plates and a top pressure of 50 to 400 Torr (6.
(67-53.3 kPa), operating at a bottom temperature of 150-250 ° C. The fraction can be further purified, if necessary, to give high-purity 1,2BG. The fraction is returned to the hydrolysis reaction to hydrolyze unreacted substances to produce 1,4BG. Thus, in countercurrent multistage hydrolysis,
When a mixture of water and acetic acid separated from the hydrolysis reaction liquid is used for the hydrolysis reaction in the preceding stage, a part of the mixture is extracted in the acetic acid recovery step, whereby efficient hydrolysis can be performed.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. The following “%” represents “% by weight”. Example 1 The reaction was carried out according to the attached drawings. 1, 2 DAB
2%, 1,2HAB 4.2%, 1,4DAB
15930 kg / hr of a diacetoxybutane-containing liquid containing 2% and 2.6% of 1,4HAB was mixed with 5420 kg / h of a mixture of water and acetic acid distilled from the top of the second water acetic acid separation column.
r, a mixture of 5110 kg / hr of water and acetic acid distilled from the top of the third water acetic acid separation tower was continuously supplied to the first hydrolysis reactor together with 5110 kg / hr to perform a hydrolysis reaction. At this time, 5000 kg / hr of the hydrolysis reaction liquid obtained from the outlet of the reactor
Was circulated to the reactor inlet. The first hydrolysis reactor is an ion exchange resin (manufactured by Mitsubishi Chemical Corporation, SK-1BH) 60 m
^In a reactor filled with ³ , pressure 0.2MPa, temperature 50 ℃
Driven by

The hydrolysis reaction solution flowing out from the bottom of the first reactor was supplied to a first water acetic acid separation column to separate water and acetic acid. The acetic acid separation column is a distillation column having five theoretical stages, and is subjected to reduced pressure (0.04
(MPa), and the acetic acid concentration in the bottom liquid was adjusted to 0.5% or less. 12080 kg of the obtained bottom liquid
/ Hr was supplied to the second hydrolysis reactor together with a mixture of water and acetic acid (11900 kg / hr) which had flowed out from the top of the third acetic acid separation tower to perform a hydrolysis reaction. Mixture of water and acetic acid distilled from the first water acetic acid separation tower 14390 kg / hr
Was supplied to an acetic acid recovery step to recover acetic acid.

The second hydrolysis reactor was a reactor filled with 60 m ³ of an ion exchange resin (manufactured by Mitsubishi Chemical Corporation, SK-1BH) and operated under the same conditions as the first hydrolysis reactor. The reaction solution flowing out of the second hydrolysis reactor was supplied to a second acetic acid separation tower to separate water and acetic acid. The second acetic acid separation tower is a distillation column having five theoretical stages, and under reduced pressure (0.04MP
The operation was carried out in a) so that the acetic acid concentration in the bottom liquid was 0.5% or less. Mixture of effluent water, acetic acid 1358
Of the 0 kg / hr, 5420 kg / hr was supplied to the first hydrolysis reactor, and the remainder was supplied to the acetic acid recovery step to recover acetic acid. The product obtained from the bottom is supplied to a middle side stream 30 containing freshly supplied water of 15480 kg / hr and 1,4-diacetoxybutane recovered in the unreacted material recovery tower.
Together with 00 kg / hr to a third hydrolysis reactor,
A hydrolysis reaction was performed. The third hydrolysis reactor is an ion exchange resin (manufactured by Mitsubishi Chemical Corporation, SK-1BH) of 80 m.
^{It was} packed with ³ and operated under the same conditions as the first hydrolysis reactor. The reaction liquid flowing out of the third hydrolysis reactor is the third liquid.
The mixture was supplied to an acetic acid separation tower to separate water and acetic acid. The third acetic acid separation column is a distillation column having five theoretical stages, and is under reduced pressure (0.04MP
The operation was carried out in a) so that the acetic acid concentration in the bottom liquid was 0.5% or less. Mixture of effluent water, acetic acid 1704
Of the 0 kg / hr, 11930 kg / hr was supplied to the second hydrolysis reactor, and the remainder was supplied to the first hydrolysis reactor. From the bottom, a product having the composition shown in Table 1 was obtained, supplied to the unreacted material recovery tower, and the unreacted material and 1,4-butanediol were separated. The mixture of water and acetic acid distilled here was 44980 kg / hr in total, and the steam used for distillation was 64000 kg / hr including the acetic acid recovery step. (0.4MPa steam conversion)

[0026]

[Table 1] Table-1 1,2HAB 1.2% 1,2BG 12.4% 1,4DAB 1.4% 1,4BG 63.3%

The unreacted material recovery column is a distillation column having a packing of 96 theoretical plates, and has a top pressure of 0.01 MPa and a reflux ratio of 8
0, and distillate 1040 kg / hr of a fraction containing 1,2-butanediol as the main component from the top of the column,
1,4-diacetoxybutane 1
2.9%, 1-hydroxy-4-acetoxybutane 6
5160 kg / hr of a side stream containing 4.9% and 19.1% of 1,4-butanediol was distilled off, and 1,4-butanediol (purity: 99.5%) was removed from the bottom of the column at 5370k.
g / hr was extracted. 3000 kg / hr of side flow
Was supplied to the THF conversion step as a raw material for THF, and the remainder was supplied to the third hydrolysis reactor.

Comparative Example 1 Using the same raw materials as in Example 1, the amount of raw water newly supplied to the hydrolysis reaction so that the composition of the bottoms of the third water acetic acid separation column is the same as in Example 1. Was adjusted to perform a hydrolysis reaction. During this period, the entire amount of the mixture of water and acetic acid distilled off in the second and third water acetic acid separation towers was supplied to the hydrolysis reactor at the preceding stage, and the hydrolysis reaction was performed at the same temperature and pressure as in Example 1. The amount of raw water supplied to the third hydrolysis reactor is 13
The mixture of water and acetic acid distilled from the first, second, and third water acetic acid separation columns at a rate of 100 kg / hr was 2007, respectively.
0 kg / hr, 16000 kg / hr, 14400 kg
/ Hr, which is 50470 kg / hr in total.
The total amount of steam used for distillation was 66
000 kg / hr. (0.4MPa steam conversion)

[0029]

According to the present invention, in the production of butanediol by hydrolysis of diacetoxybutane, the amount of steam used for separating water and acetic acid obtained by hydrolysis is reduced, which is industrially advantageous. Butanediol can be produced.

[Brief description of the drawings]

FIG. 1 is a flow sheet of Example 1.

[Explanation of symbols]

 I First hydrolysis reactor I 'First water acetic acid separation tower II Second hydrolysis reactor II' Second water acetic acid separation tower III Third hydrolysis reactor III 'Third water acetic acid separation tower IV Unreacted material recovery Tower

Claims (3)

[Claims] Claims 1. A diacetoxybutane is hydrolyzed by contacting it with water in the presence of a solid acid catalyst, separating water, acetic acid and crude butanediol, and then purifying the crude butanediol to obtain a high-purity crude butanediol. In the method for producing butanediol, the method has at least two combinations of a hydrolysis reaction step and a subsequent separation step of water, acetic acid and crude butanediol, and is recovered from the hydrolysis reaction liquid of the second and subsequent stages. A method for producing butanediol, comprising extracting a part of water and acetic acid out of the system, and then using it as a raw material water for a hydrolysis reaction preceding the hydrolysis reaction. 2. The method according to claim 1, wherein the method comprises at least three combinations of a hydrolysis reaction step and a subsequent separation step of water, acetic acid and crude butanediol. 3. The water and acetic acid mixture circulated from the second water acetic acid separation column by circulating 40 to 80% by weight of the water and acetic acid mixture from the second water acetic acid separation column to the first hydrolysis reactor. 6 of
The method according to claim 1 or 2, wherein 0% by weight or more is circulated to the second hydrolysis reactor.