JPH06321846A - Method for recovering acetic acid from waste oil mixture - Google Patents

Abstract

PURPOSE:To efficiently recover acetic acid as an active ingredient from a waste oil mixture comprising a high-boiling substance occurring in a process for producing 1,4-butanediol and tetrahydrofuran from butadiene, acetic acid, etc., as starting raw materials. CONSTITUTION:A waste oil mixture composed of one or more high-boiling substances of (1) a first high-boiling substance obtained after separation of diacetoxybutene by distillation from a reactional product prepared by reacting butadiene with acetic acid and oxygen, (2) a second high-boiling substance 7 obtained after separation of diacetoxybutane from a reactional product prepared by hydrogenating diacetoxybutene and (3) a third high-boiling substance 14 obtained after separation of butanediol and/or tetrahydrofuran from a reactional product prepared by reacting diacetoxybutane with water in the presence of an acid catalyst is hydrolyzed 17 in the presence of 100-5,000wt. ppm based on the waste oil mixture of a mineral acid at 40-150 deg.C and then distilled 18 to give a method for recovering acetic acid from the waste oil mixture, characterized by acquisition of water and acetic acid as distillate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for recovering acetic acid from a waste oil mixture. More specifically, it relates to a method for acetic acidification of butadiene with acetic acid and oxygen, followed by hydrogenation, hydrolysis and cyclization to recover acetic acid from a waste oil mixture produced in each step of producing 1,4-butanediol and tetrahydrofuran.

[0002]

2. Description of the Related Art The so-called butadiene method, which is characterized in that butadiene is acetoxylated, then hydrogenated, and further hydrolyzed or deacetic acid-cyclized, is a typical method for industrially producing 1,4-butanediol and tetrahydrofuran. Method. Also in this butadiene method, as in the case of industrial processes of other chemicals,
Separation of inevitable by-products and efficiency of treatment are important problems.

For example, a large amount of acetic acid and water in the reaction solution can be separated and recovered, and most of them can be reused as a reaction raw material. In addition, among the diacetoxybutenes produced by acetoxylation of butadiene, various isomers such as 2,4, 3,4, etc. other than 1,4 as an active ingredient are usually discarded after separation. However, it is also possible to isomerize the 1,4 compound using a catalyst and reuse it.

Further, in JP-A-52-148014, after diacetoxylating butadiene, 1,4-diacetoxybutene, which is an active ingredient, is separated, and the balance is kept at 300 ° C. or lower in the presence of an acid catalyst. A method is disclosed in which heat treatment is performed to decompose butadiene and acetic acid, and the butadiene and acetic acid are recycled to the reaction step.

[0005]

As described above, as described above,
As for by-products, various proposals have been made regarding the method of recycling specific components such as light-boiling solvent components and isomers. However, the high-boiling components, which accumulate in small amounts at each step of the manufacturing process, and which are usually difficult to identify the structure in many cases, have conventionally been discarded exclusively as a waste oil mixture.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies over the years for rationalizing the production process of 1,4-butanediol and tetrahydrofuran by the butadiene method. As a result, the waste oil recovered in the production process It was found that a large amount of a compound having an acetic acid ester structure was contained in the mixture, and based on this, a method for efficiently recovering acetic acid from the waste oil mixture was investigated, and the present invention was completed.

That is, the gist of the present invention is (1) a first high boiling point product obtained by distilling and separating diacetoxybutene from a reaction product obtained by reacting butadiene, acetic acid and oxygen,
(2) A second high-boiling substance obtained by distilling and separating diacetoxybutane from a reaction product obtained by hydrogenating diacetoxybutene, (3) obtained by reacting diacetoxybutane with water in the presence of an acid catalyst. A waste oil mixture comprising a third high boiling point obtained by distilling and separating butanediol and / or tetrahydrofuran from the reaction product obtained, and a waste oil mixture comprising any one or more of the above high boiling points (1) to (3), For 100 ~
40-150 ° C. in the presence of 5000 ppm by weight of mineral acid
The method comprises recovering acetic acid from a waste oil mixture, which is characterized in that water and acetic acid are obtained as a distillate by hydrolyzing with, followed by distillation.

The present invention will be described in detail below. The waste oil mixture targeted by the present invention comprises any one or more of acetoxylation reaction of butadiene, hydrogenation reaction of diacetoxybutene, or reaction of 1,4-diacetoxybutane in the presence of water and an acid catalyst. It is a high boiling point product of the reaction. That is, it means a high-boiling substance generated in the reaction of a series of steps for producing 1,4-butanediol or tetrahydrofuran using butadiene, acetic acid or the like as a starting material. A large amount of acetic acid ester is contained in the waste oil mixture, and the main ones are 1,4-diacetoxybutane,
Examples are 1,4-diacetoxybutene, 1,1,4-triacetoxybutene, 1,1,4-triacetoxybutane, diacetoxyoctene, and diacetoxyoctane. However, most of the acetic acid ester is considered to be a polymer derived from diacetoxybutene or butadiene, and it is difficult to specify its structure. Then, it is estimated that these waste oil mixtures usually contain about 30 to 60% of acetate roots.

The above waste oil mixture is by-produced and recovered in the steps of the following known reaction method. (1) Acetoxylation step Usually, it is carried out by reacting butadiene, acetic acid and molecular oxygen in the presence of a palladium-based catalyst, usually in a temperature range of 40 to 180 ° C. under a pressure condition of atmospheric pressure or higher. As a method for separating diacetoxybutene from the reaction product,
A method in which water, acetic acid, and other light-boiling components are first separated by distillation, and then diacetoxybutene and high-boiling substances are separately separated by distillation is preferable.

(2) Hydrogenation step Usually, diacetoxybutene is brought into contact with hydrogen in the presence of a noble metal catalyst such as palladium or ruthenium, and usually 40 to 1
It is carried out by reacting in a temperature range of 80 ° C. under a pressure condition of atmospheric pressure or higher. The reaction product is usually subjected to distillation,
Separated into diacetoxybutane and high boilers.

(3) Hydrolysis or Deacetic Acid Cyclization Step When diacetoxybutane is reacted with water in the presence of an acid catalyst and the reaction conditions are selected to mainly produce butanediol, tetrahydrofuran is mainly used. In the case of producing, butanediol is mainly produced in the first reaction, and then unreacted diacetoxybutane or a reaction intermediate monoacetoxybutane is recovered and another reaction is performed with respect to these to produce tetrahydrofuran, or butanediol It is possible to coproduce both and tetrahydrofuran at a desired ratio.

The acid catalyst used in the reaction is usually a solid acid catalyst, preferably a strongly acidic cation exchange resin. As the reaction conditions, the reaction temperature is usually 40 to 100 ° C. in the case of hydrolysis reaction, and is usually 50 to 120 ° C. in the case of cyclization reaction during deacetic acid. Is set to a higher temperature condition. However, the reaction selectivity can be adjusted by appropriately setting other conditions such as the residence time of the reaction solution in the reaction zone and the amount of the reaction solution circulated to the reaction zone (Japanese Patent Laid-Open No. 52-1).
11557, JP-A-53-87305, JP-A-54-3
2409, JP-A-57-108030, etc.). Since the reaction product contains various components such as acetic acid, water, other light-boiling components, high-boiling substances, unreacted raw materials, and intermediates, usually, a plurality of distillation columns are installed to separate each component. .

The present invention is characterized in that the waste oil mixture obtained by recovering the high boiling point product from the above steps is treated by a specific method to recover the acetic acid content as an active ingredient. The method for treating a waste oil mixture according to the present invention is 100 to 5 for the waste oil mixture.
000 weight ppm, preferably 300 to 2000 weight p
40-150 ° C., preferably 60, in the presence of pm mineral acid.
Hydrolysis is carried out at a temperature of 130 ° C. Under such conditions, the acetic acid ester in the waste oil mixture can be efficiently hydrolyzed even with a low concentration of mineral acid. If the amount of mineral acid exceeds 2000ppm, or if the temperature is 150
When the temperature is higher than 0 ° C, the economic merit is lowered, and it is not preferable in view of safety, corrosiveness of the material of the reactor and the like. Also, the amount of mineral acid is less than 100 ppm,
Alternatively, if the temperature is lower than 40 ° C., the hydrolysis rate remarkably decreases, which is not efficient. The mineral acid used is not particularly limited, such as nitric acid, sulfuric acid, phosphoric acid, but the formation of a polymer,
Nitric acid is preferable because of problems such as corrosiveness.

In addition, as the condition of hydrolysis, the amount of water added to the reaction system is not particularly limited, but is usually 30 to 70% by weight with respect to the waste oil mixture, and a large amount of acetate is contained in the waste oil mixture. However, it is preferable to increase the amount of water. The pressure in the reaction zone is not particularly limited and may be normal pressure, reduced pressure or increased pressure. The reaction time for the above hydrolysis is usually 1 to 20 hours, preferably 3 to 10 hours, and is carried out in a batch or continuous reactor.
The material of the reactor is preferably one having excellent corrosion resistance, but usually SUS-304, SUS-31
A general stainless steel mesh such as 6 is sufficient.

The reaction liquid after hydrolysis is distilled in a distillation column to obtain water and acetic acid as distillates. The conditions of the distillation column are not particularly limited, but the column bottom temperature is usually 120 to 19
It is preferable to carry out at 0 ° C. and the column top pressure in the range of 30 to 300 mmHg. The acetic acid in the distillate can be reused as a raw material for the acetoxylation reaction of butadiene described above, but is not particularly limited thereto. In addition, the bottom liquid is removed from the system and is normally discarded, but again subjected to the above-mentioned hydrolysis treatment,
It is also possible to recover the residual acetic acid content.

[0016]

EXAMPLES The present invention will now be described in more detail with reference to examples. Example 1 A treatment example of a waste oil mixture in the process for producing butanediol and tetrahydrofuran from butadiene and acetic acid raw materials shown in FIG. 1 will be described.

Reactor 1 filled with a palladium-supported catalyst
, Butadiene 1.6 t / H, air 1100 Nm ³ / H,
Acetic acid was supplied at 30 t / H and reacted at 90 KG and 100 ° C. The reaction liquid was subjected to solid-liquid separation (not shown), then acetic acid, water, and other light-boiling components were distilled off in the distillation column 2, and diacetoxybutene was distilled in the distillation column 3. Further, the bottoms of the distillation column 3 is distilled by the thin film evaporator 4 operated at a pressure lower than the bottom pressure of the distillation column 3, and the distillate is circulated to the distillation column 3 so as to have a higher boiling point than the bottom of the column. Was extracted at 150 Kg / H.

Next, the diacetoxybutene distilled from the distillation column 3 was subjected to hydrogenation reaction at a reaction pressure of 10 KG and a temperature of 90 ° C. under hydrogen flow in a reactor 5 filled with a palladium catalyst. Then, the reaction solution was distilled in the distillation column 6 to distill diacetoxybutane. The bottoms of the distillation column 6 is a high boiling point recovery column 7 operated at a pressure lower than the bottom pressure of the distillation column 6.
The distillation was circulated in the distillation column 6, and the high-boiling substance was extracted from the bottom of the column at 30 kg / H.

Next, the diacetoxybutane distilled from the distillation column 6 is a reactor 8 filled with a strongly acidic ion exchange resin,
In 10 to carry out a two-stage hydrolysis reaction at 50 ° C.,
A reaction mixture containing butanediol, hydroxyacetoxybutane and diacetoxybutane as main components was prepared. From the hydrolyzed liquid, acetic acid, water and other light boiling components were distilled off in distillation columns 9 to 11. The bottoms of the distillation column 11 were supplied to the distillation column 12 to distill light fractions from the top, diacetoxybutane and hydroxyacetoxybutane from the upper side stream, and butanediol from the middle side stream. Then, butanediol was rectified in the distillation column 13 and recovered as a product stream of butanediol. Further, the bottom liquid of the distillation columns 12 and 13 is distilled in a high boiling point recovery column 14 operated at a pressure lower than that of the distillation columns 12 and 13, and the distillate is circulated to the distillation column 12. Then, the high boiling substance was extracted from the bottom of the column at 50 kg / H.

The upper side stream of the distillation column 12 is supplied to a reactor 15 filled with a strongly acidic ion exchange resin, and the temperature is 80 ° C.
After carrying out the deacetic acid cyclization with, the reaction solution was sent to the distillation column 16,
Tetrahydrofuran was distilled off, part of the bottom liquid was returned to the reactor 15, and the other was returned to the distillation column 6 to recover unreacted materials.

The acetoxylation of butadiene as described above,
Waste oil mixture 230 kg / H (about 45% by weight of acetate radical: alkali hydrolyzate) consisting of a high boiling point collected in each step of hydrogenation of diacetoxybutene, hydrolysis of diacetoxybutane and deacetic acid cyclization. Value analyzed by chromatography), water 150 kg / H and 60% by weight nitric acid 0.
The liquid in which 5 kg / H was mixed in advance was supplied to the hydrolysis reactor 17 made of SUS-304. In the hydrolysis reactor 17, the hydrolysis reaction was carried out at a temperature of 92 ° C. and normal pressure for 7 hours (amount of nitric acid to the waste oil mixture was 600 ppm by weight). Next, the hydrolysis reaction liquid was distilled in a distillation column 18 under conditions of a column top pressure of 100 mHg and a column bottom temperature of 148 ° C., and 180 parts of acetic acid aqueous solution (45% by weight of acetic acid) was obtained as a distillate ( Acetate recovery from waste oil mixture 60%).

[0022]

According to the present invention, it has been conventionally discarded.
Since the waste oil mixture consisting of high-boiling substances generated in the step of producing 1,4-butanediol or tetrahydrofuran using butadiene, acetic acid or the like as a starting material, the acetic acid content as an active ingredient can be efficiently recovered, The unit can be greatly improved.

[Brief description of drawings]

FIG. 1 is an example of an embodiment of the present invention.

[Explanation of symbols]

1, 5, 8, 10, 16 ... Reactor of each step 2, 3, 6, 9, 11, 12, 13, 16, 18 ... Distillation tower 4 ... Thin film distiller 7, 14 ... High boiling point recovery tower 17 … Hydrolysis reactor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number in the agency FI technical display location // C07B 61/00 300 (72) Inventor Kazu Amane Suma 2-5 Marunouchi, Chiyoda-ku, Tokyo Sanritsu Kasei Co., Ltd.

Claims (2)

[Claims] 1. A first high boiling point product obtained by distilling and separating diacetoxybutene from a reaction product obtained by reacting butadiene, acetic acid and oxygen, and (2) obtained by hydrogenating diacetoxybutene. Second high boiling point after diacetoxybutane is separated from the reaction product by distillation, (3) Butanediol and / or tetrahydrofuran is obtained from the reaction product obtained by reacting diacetoxybutane with water in the presence of an acid catalyst. The third high-boiling substance after separation by distillation, and a waste oil mixture comprising any one or more of the above high-boiling substances (1) to (3) is added to the waste oil mixture in an amount of 100 to 500.
A method for recovering acetic acid from a waste oil mixture, characterized in that water and acetic acid are obtained as distillates by hydrolyzing at 40 to 150 ° C. in the presence of 0 ppm by weight of mineral acid, and then distilling. 2. The method of claim 1 wherein the mineral acid is nitric acid.