JPH09208515A - Production of acrylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently, economically and advantageously produce high-quality acrylic acid useful as a monomer for various polymers or a raw material for various polymerizable esters. SOLUTION: The azeotropic dehydration treatment of an acrylic acid- containing oxidation product liquid obtained by catalytically oxidizing propylene and/or acrolein in the vapor phase is carried out and an agent for removing aldehydes (e.g. hydrazine hydrate or o-phenylenediamine) is then added thereto. The distillation and purification are subsequently performed to afford the objective acrylic acid. At least one amine selected from aliphatic amines, heterocyclic amines and aromatic amines and the agent for removing the aldehydes are preferably added to the liquid undergoing the azeotropic dehydration treatment at this time.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing acrylic acid, and more specifically, to efficiently produce acrylic acid of excellent quality from an acrylic acid-containing oxidation product solution obtained by catalytic gas phase oxidation of propylene or acrolein. In addition, the present invention relates to a method for producing acrylic acid which is economically and advantageously recovered.

[0002]

2. Description of the Related Art Acrylic acid is a highly reactive α, β-unsaturated carboxylic acid, and as a monomer of various polymers,
Alternatively, it is an important compound used as a raw material for various polymerizable esters, and is widely used in many fields. This acrylic acid is currently industrially produced by the direct oxidation method of propylene. The method for producing acrylic acid by direct oxidation of propylene can be roughly classified into a one-step oxidation method and a two-step oxidation method. The former one-step oxidation method is a method of directly obtaining acrylic acid from propylene,
Acrolein produced as a by-product is recycled. On the other hand, the two-stage oxidation method is a method of first producing acrolein by oxidation of propylene and then reoxidizing acrolein to obtain acrylic acid. The oxidation product liquid obtained by these oxidation methods is in the form of an acrylic acid-containing aqueous solution because steam is used for the reaction. Therefore, in order to recover acrylic acid from this oxidation product liquid, usually, first,
A method is used in which acrylic acid is obtained by subjecting an oxidation product solution to dehydration treatment and then distillation purification.

As a method for dehydrating the above-mentioned oxidation product solution,
The solvent extraction method and the azeotropic dehydration method are generally known, but the latter azeotropic dehydration method is economically advantageous. by the way,
This oxidation product solution contains aldehydes such as furfural and benzaldehyde, which are difficult to separate from acrylic acid by distillation, and it is necessary to remove these aldehydes in order to obtain good quality acrylic acid. There is.
Therefore, conventionally, a method has been adopted in which, after dehydration treatment of an oxidation product liquid, for example, hydrazine hydrate is added to the treatment liquid to react with aldehydes, and then purified by distillation. However, in the oxidation product liquid, maleic acid is contained as a by-product together with the above-mentioned aldehydes, and when this maleic acid adopts an azeotropic dehydration method as a dehydration treatment method,
It remains in the treatment liquid without being removed. Therefore, when hydrating hydrazine is added to this treatment liquid for the purpose of removing aldehydes such as furfural, hydrating hydrazine easily reacts with maleic acid to form maleic acid hydrazide, and thus a large amount of hydrating hydrazine is added. Need to be added,
It is inevitable that the cost will increase.

On the other hand, when the solvent extraction method is adopted as the dehydration method, maleic acid is easily removed. Therefore, it is not necessary to add a large amount of hydrated hydrazine as in the above azeotropic dehydration method, but the solvent extraction method is used. As such, it is more costly than the azeotropic dehydration method. Therefore, until now, it has been attempted to add various dealdehyde agents other than hydrated hydrazine to the treated liquid after the azeotropic dehydration treatment of the oxidation product liquid for purification by distillation, but the effect is insufficient. In reality, it has not been put to practical use because the dealdehyde agent is expensive.

[0005]

SUMMARY OF THE INVENTION Under the circumstances, the present invention has a low content of aldehydes such as furfural from an acrylic acid-containing oxidation product solution obtained by catalytic gas phase oxidation of propylene or acrolein. It is an object of the present invention to provide a practical acrylic acid production method capable of efficiently and economically recovering acrylic acid of excellent quality.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventor has carried out an azeotropic dehydration treatment on an acrylic acid-containing oxidation product solution, and then de-aldehydeing this treatment solution. When an acrylic acid is added by distillation to purify acrylic acid, maleic acid easily reacts with amines by adding amines capable of reacting with maleic acid and a dealdehyde agent to the azeotropic dehydration treatment liquid. Since the consumption of maleic acid in the aldehyde agent is suppressed, it has been found that acrylic acid of excellent quality can be efficiently obtained and the object thereof can be achieved even if a small amount of dealdehyde agent is added. The present invention has been completed based on such findings. That is, the present invention is an azeotropic dehydration treatment of an acrylic acid-containing oxidation product liquid obtained by catalytic vapor phase oxidation of propylene and / or acrolein, and then a dialdehyde agent is added to distill and purify acrylic acid. For boiling dehydration treatment liquid,
Provided is a method for producing acrylic acid, which comprises adding at least one amine selected from an aliphatic amine, a heterocyclic amine and an aromatic monoamine and a dealdehyde agent.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the method of the present invention, an acrylic acid-containing oxidation product liquid obtained by catalytic gas phase oxidation of propylene and / or acrolein is used. The acrylic acid-containing oxidation product liquid may be a reaction product liquid obtained by the one-stage oxidation method of propylene or a reaction product liquid obtained by the two-stage oxidation method. Since this acrylic acid-containing oxidation product liquid uses water vapor for the reaction,
Obtained in the form of an aqueous solution of acrylic acid. The composition of the acrylic acid-containing oxidation product liquid varies depending on the type of oxidation method, reaction conditions, etc., but in general, the content of each component is 50-80% by weight of acrylic acid, 20-50% by weight of water, Maleic acid is 0.2 to 1.0% by weight, furfural 100 to 500 ppm by weight, and benzaldehyde 100 to 500 ppm by weight. In the method of the present invention, first, this acrylic acid-containing oxidation product liquid is subjected to azeotropic dehydration treatment to remove water. The azeotropic dehydration treatment method is not particularly limited, and a method conventionally used in the production of acrylic acid can be used. For example, as an azeotropic agent, toluene, heptane, methyl isobutyl ketone, diisobutyl ketone, diisobutylene, or the like is used, and 100 to 150 is used.
Azeotropic dehydration is performed at a pressure of about torr. Due to this azeotropic dehydration treatment, the water content in the oxidation product liquid is usually 100.
It becomes less than ppm by weight.

Next, amines and a dealdehyde agent are added to the azeotropic dehydration treatment liquid thus obtained. The former amines are for removing maleic acid, and the latter dealdehyde agents are for removing aldehydes such as furfural and benzaldehyde. It is necessary that the amines have reactivity with maleic acid, and in the present invention, aliphatic amines, alicyclic amines, and aromatic monoamines are used. The type of these amines is not particularly limited as long as it easily reacts with maleic acid and the reaction product does not decompose during distillation, and various types can be used. For example, as the aliphatic amine, a straight chain having 1 to 10 carbon atoms,
Branched and cyclic alkyl monoamines and alkylene polyamines, as well as monoamines and polyamines in which amines have been introduced into the side alkyl groups of arylalkyl groups, such as methylamine, ethylamine, n-propylamine, isopropylamine , Butylamine, hexylamine, ethanolamine, propanolamine, ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine, cyclopentylamine, cyclohexylamine, cyclohexylenediamine, benzylamine, phenethylamine, xylylenediamine and the like. Moreover, examples of the heterocyclic amine include pyridine, piperidine, piperazine, and pyrrolidine. Further, examples of the aromatic monoamine include aniline, toluidine, xylidine and the like. Among these amines, aliphatic amines are preferable from the viewpoint of reactivity with maleic acid and economy.
Particularly, ethylenediamine and diethylenetriamine are preferable. These amines may be used alone or in combination of two or more.

On the other hand, the dealdehyde agent is not particularly limited as long as it can easily react with aldehydes such as furfural and benzaldehyde, but is not particularly limited, but from the viewpoint of effect and economical efficiency, hydrazine hydrate and free hydrazine can be used. Hydrazine,
Hydrazines such as hydrazine salts and phenylenediamines are preferable, and hydrated hydrazine and o-phenylenediamine are particularly preferable. These dealdehyde agents may be used alone or in combination of two or more. In the present invention, the azeotropic dehydration treatment liquid is subjected to distillation by adding amines and a dealdehyde agent, but the addition method of the amines and a dealdehyde agent is not particularly limited,
Various methods can be used. For example, (1) a method in which amines and a dealdehyde agent are simultaneously added to an azeotropic dehydration treatment liquid, then light components are separated by distillation, and then acrylic acid is distilled and purified, and (2) an azeotropic dehydration treatment liquid. , Firstly adding amines and reacting with maleic acid, then adding dealdehyde agent and reacting with aldehydes such as furfural, then distilling and separating light components, and then distilling and refining acrylic acid. Method, (3) First, after adding amines to the azeotropic dehydration treatment liquid, the light fraction is separated by distillation, then a dealdehyde agent is added to the light fraction separation treatment liquid, and then acrylic acid is purified by distillation. How to do,
(4) A method in which an azeotropic dehydration treatment liquid, an amine and a dealdehyde agent are separately and simultaneously supplied to a light fraction separation column, and they are brought into contact with each other in the column. After adding the amines, the light fraction is separated by distillation, and then the light fraction separation treatment liquid and the dealdehyde agent are simultaneously and separately added to the distillation purification column of acrylic acid, and they are contacted in the column. Method (6) An azeotropic dehydration treatment liquid and amines are separately supplied to a light fraction separation column at the same time, and they are brought into contact with each other, and then a dealdehyde agent is added to the light fraction separation component. After that, the method of distilling and refining acrylic acid, and (7) separately supplying the azeotropic dehydration treatment liquid and the amines to the light fraction separation column at the same time to bring them into contact with each other, and then the light fraction. Distillation of acrylic acid with separation treatment liquid and dealdehyde agent At the same time supplied separately to the manufacturing tower,
A method of bringing them into contact with each other in the tower can be used.

Among the above methods, the methods (3) and (6) are particularly preferable in order to achieve the object of the present invention more effectively. The amount of amines added to the azeotropic dehydration treatment liquid is preferably 0.5 times equivalents or more, and particularly preferably 1 times equivalents or more, with respect to the maleic acid present. The amount of the treatment liquid is usually about 0.1 to 1.0% by weight. From the viewpoint of the effect, the addition temperature is usually about 15 to 100 ° C., preferably 20 to 50 ° C. in the case of (3) and 50 to 70 ° C. in the case of (6). Further, the contact time is not particularly limited, but several seconds to 10 minutes is sufficient. On the other hand, the addition amount of the dealdehyde agent to the azeotropic dehydration treatment liquid or the light fraction separation treatment liquid is preferably 0.5 times equivalent or more, and particularly preferably 2 times equivalent or more with respect to the existing aldehydes. In addition, the processing liquid is usually 0.01 to 0.5.
It is about% by weight. From the viewpoint of effect, the addition temperature is usually 1
It is in the range of about 5 to 100 ° C, preferably 20 to 50 ° C. Further, the contact time is not particularly limited, but is several seconds to 1
It takes about 0 minutes. Distillation of light components is usually performed at a pressure of 80.
It is carried out under conditions of about 130 torr and a bottom liquid temperature of about 80 to 110 ° C. By this operation, the light components generated by the oxidation reaction and the azeotropic agent are removed. Further, the distillation purification of acrylic acid is usually carried out under the conditions of a pressure of about 50 to 100 torr and a bottom liquid temperature of about 60 to 90 ° C. By such an operation, high-quality acrylic acid having a purity of 99% or more with a low content of aldehydes such as furfural and maleic acid can be easily produced.

[0011]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The analysis of aldehydes and maleic acid is performed by gas chromatography, and
The water concentration in the purified acrylic acid was measured by the Karl Fischer method and the gas chromatography method.

Example 1 Acrylic acid-containing oxidation product liquid obtained by one-step catalytic gas phase oxidation of propylene (59% by weight of acrylic acid, 40% by weight of water, 0.5% by weight of maleic acid, 150 ppm by weight of furfural, 200 of benzaldehyde) (Ppm by weight) was subjected to the following operation to obtain purified acrylic acid. (1) Azeotropic dehydration treatment A small distillation apparatus (dehydration tower) having a diameter of 1 inch and a length of 60 cm filled with a filler was charged with the above oxidation product solution at a rate of 35 ml / hour and toluene as an azeotropic agent. 13
It was supplied at a rate of 5 ml / hour, and azeotropic dehydration treatment was performed under the conditions of a pressure of 130 torr at the top and a temperature of 47 ° C. As a result, acrylic acid 90 wt%, toluene 9 wt%, maleic acid 7330 wt ppm, furfural 313 wt ppm, benzaldehyde 458 wt p
An azeotropic dehydration treatment liquid containing pm and a water content of less than 100 ppm by weight was obtained. (2) Distillation separation treatment of light components To the azeotropic dehydration treatment liquid obtained in the above (1), 4000 ppm by weight of ethylenediamine was added at 90 ° C., and this liquid was filled with a filler to a diameter of 1 inch. , A small distillation apparatus (light fraction separation column) with a length of 60 cm was supplied at a rate of 30 ml / hour, and the pressure at the top was 110 torr.
r, temperature 52 ° C., pressure at bottom 110 torr,
Distillation separation treatment of light components was performed under the condition of a temperature of 91 ° C. (3) Distillation purification treatment of acrylic acid 2280 ppm by weight of hydrazine hydrate was added at 25 ° C. to the light component separation treatment liquid obtained in the above (2), and the liquid was filled with a filler having a diameter of 1 30 ml / in a small distillation unit (acrylic acid refining tower) with an inch and a length of 60 cm
Supply at the speed of time, pressure 70tor at the top
The distillation purification treatment of acrylic acid was performed under the conditions of r, temperature 62 ° C., bottom pressure 70 torr, and temperature 80 ° C.

As a result, maleic acid and furfural were almost completely removed, and the water content in the purified acrylic acid was 560 ppm by weight. The results are shown in Table 1. Examples 2 and 3 In Example 1, ethylenediamine 4000 weight pp
In place of m, the type and amount of amine shown in Table 1 is used,
Moreover, purified acrylic acid was obtained in the same manner as in Example 1, except that the amount of hydrated hydrazine was changed as shown in Table 1. The results are shown in Table 1. Example 4 In Example 1, ethylenediamine 4000 weight pp
8000 weight ppm of diethylenetriamine instead of m
Was used, and purified acrylic acid was obtained in the same manner as in Example 1 except that 1620 ppm by weight of o-phenylenediamine was used instead of 2280 ppm by weight of hydrated hydrazine. The results are shown in Table 1. Comparative Example 1 Purified acrylic acid was obtained in the same manner as in Example 1 except that ethylenediamine was not added and the amount of hydrated hydrazine was changed to 3760 ppm by weight. The results are shown in Table 1. Comparative Examples 2 to 4 In Example 1, ethylenediamine 4000 weight pp
Purified acrylic acid was obtained by treating in the same manner as in Example 1 except that the kind and amount of amine shown in Table 1 were used in place of m and no hydrazine hydrate was added. First result
It is shown in the table.

[0014]

[Table 1]

[0015]

[Table 2]

As a result of the above, the method of the present invention (Examples 1 to 1)
In 4), maleic acid and furfural are found to be almost completely removed. On the other hand, Comparative Example 1 is the addition of hydrated hydrazine alone without addition of amine. In this case, a large amount of hydrated hydrazine is required to remove furfural, and as a result, the water concentration in purified acrylic acid is increased. You can see that is getting higher. In Comparative Examples 2 to 4, no dealdehyde agent was added, and amines were added alone.
In this case, it is understood that the removal rates of furfural and maleic acid are low, and the water concentration in the purified acrylic acid is high.

[0017]

EFFECTS OF THE INVENTION According to the method of the present invention, high-quality acrylic acid can be efficiently and economically recovered from an oxidation product solution obtained by catalytic vapor-phase oxidation of propylene or acrolein. it can.

Claims (7)

[Claims] 1. An azeotropic method for azeotropically dehydrating an acrylic acid-containing oxidation product solution obtained by catalytic vapor-phase oxidation of propylene and / or acrolein and then adding a dealdehyde agent to distill and purify acrylic acid. For dehydration treatment liquid,
A method for producing acrylic acid, which comprises adding at least one amine selected from an aliphatic amine, a heterocyclic amine and an aromatic monoamine and a dealdehyde agent. 2. The dealdehyde agent is hydrazine and / or
Alternatively, the production method according to claim 1, which is a phenylenediamine. 3. The production method according to claim 2, wherein the hydrazine is hydrazine hydrate. 4. The production method according to claim 2, wherein the phenylenediamines are o-phenylenediamines. 5. The method according to claim 1, wherein the amines are aliphatic amines. 6. The method according to claim 5, wherein the aliphatic amine is ethylenediamine and / or diethylenetriamine. 7. The production method according to claim 1, wherein amines are added to the azeotropic dehydration treatment liquid, and then a dealdehyde agent is added.