JP2001181233A - Method for producing (meth)acrylic ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing (meth)acrylic ester through an esterification step where the (meth)acrylic ester is produced by esterification reaction between (meth)acrylic acid and a 1-4C aliphatic alcohol in the presence of an acid catalyst and a separation/purification step where the (meth)acrylic ester is separated and purified from the resultant (meth)acrylic ester-containing mixture, involving an acid separation column, a low-boiling fraction separation column and a rectifier; wherein a polymerization inhibitor contained in the bottoms of the rectifier is effectively reused and the remaining (meth)acrylic ester in the bottoms is recovered efficiently. SOLUTION: This method for producing (meth)acrylic ester comprises circulating the bottoms from the rectifier to the esterification step and/or separation/ purification step described above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a (meth) acrylic acid ester, and more particularly, to an esterification step of performing an esterification reaction between (meth) acrylic acid and an alcohol, and an acid separation tower, a light boiler separation tower, and the like. In a method for producing a (meth) acrylic acid ester through a separation and purification step including a rectification column, a bottom product of the rectification column is subjected to an esterification step and / or
Alternatively, the present invention relates to a method of recycling the polymerization inhibitor in the bottom liquid by circulating the separation / purification step.

[0002]

2. Description of the Related Art Esterification of (meth) acrylic acid and an aliphatic alcohol having 1 to 4 carbon atoms in the presence of an acidic catalyst,
It is generally industrially practiced to produce a (meth) acrylate by separating and purifying the (meth) acrylate from the obtained esterification reaction mixture.

[0003] As a method of separating and purifying (meth) acrylic acid ester from the esterification reaction mixture, for example,
Japanese Patent Publication No. 7-64787 discloses an alcohol recovery tower,
It describes a method of providing a light-boiling matter separation tower and a high-boiling matter separation tower to separate and purify (meth) acrylic acid ester to obtain high-purity (meth) acrylic acid ester.

[0004]

The object of the present invention is to produce (meth) acrylic acid ester in high yield and to reduce the production cost of (meth) acrylic acid ester, thereby making (meth) acrylic acid ester economically advantageous. It is needless to say that it is industrially desirable to manufacture the product. Thus, an object of the present invention is to provide a method for producing a (meth) acrylic acid ester with high yield and economical advantage.

[0005]

According to the study of the present inventors, according to the method described in Japanese Patent Publication No. 7-64787, a polymerization inhibitor contained in the bottoms of a high-boiling matter separation column. Has no significant alteration, can be recycled as it is to the esterification step and the separation / purification step, and can be obtained in high yield of (meth) acrylic acid ester. The present invention has been completed based on such findings. It should be noted that the present inventors have found for the first time that the polymerization inhibitor contained in the bottoms does not have any significant deterioration.

That is, the present invention provides an esterification step of producing a (meth) acrylic acid ester by subjecting (meth) acrylic acid and an aliphatic alcohol having 1 to 4 carbon atoms to an esterification reaction in the presence of an acidic catalyst. To separate and purify the (meth) acrylic ester from the mixture containing the (meth) acrylic ester and the (meth) acrylic ester through a separation and purification process including an acid separation tower, a light-boiling matter separation tower and a rectification tower Wherein the bottom product of the rectification column is circulated to an esterification step and / or a separation / purification step.

[0007]

FIG. 1 is a system diagram showing one embodiment of the method of the present invention, and FIG. 2 is a system diagram showing another embodiment. 1 and 2, 1 is an esterification reactor, 2 is an acid separation column, 3 is a light-boiling matter separation column, 4 is a rectification column, 5
Indicates a high boiling matter separation column. Hereinafter, the present invention will be described with reference to FIG.

In the esterification reactor 1, (meth) acrylic acid and an aliphatic alcohol having 1 to 4 carbon atoms (methanol,
(Meth) acrylic acid ester is produced by subjecting it to an esterification reaction in the presence of an acidic catalyst (such as a strongly acidic cation exchange resin).

The mixture containing (meth) acrylic ester obtained in the esterification reactor 1 (referred to as (meth) acrylic ester-containing mixture in the present invention) is introduced into an acid separation column 2 where (meth) The acrylic acid is separated, and a mixture containing the remaining (meth) acrylic acid ester, unreacted alcohol, water and the like is recovered from the top of the tower.

This mixture is separated into oil and water, and the oil phase is introduced into the light-boiling substance separation column 3, where a part of the produced (meth) acrylate, unreacted alcohol, water and the like are distilled off.
The remaining crude (meth) acrylate is recovered from the bottom of the column.

Next, the crude (meth) acrylate is supplied to the rectification column 4 to recover the product (meth) acrylate from the top of the column. Then, the bottoms are circulated to, for example, the acid separation tower 2 or the light-boiling substances separation tower 3 to reuse the polymerization inhibitor in the bottoms.

A feature of the present invention is that the bottom product from the rectification column 4 is circulated to an optional portion in the esterification step and / or the separation / purification step. Specifically, the esterification reactor 1 and the acid separation column 2. It circulates to one or more of the light-boiling matter separation tower 3 and the rectification tower 4 or the high-boiling matter separation tower 5. As a result, the polymerization inhibitor contained in the bottom of the rectification column 4 can be reused for preventing polymerization in the esterification step and the separation / purification step. Therefore, the amount of the novel polymerization inhibitor used in the esterification step and the separation / purification step can be reduced, and the (meth) acrylic acid ester contained in the bottom liquid can be effectively recovered. It is possible to produce (meth) acrylic acid ester with high yield.

As the polymerization inhibitor, those generally used in this type of reaction can be used. For example, N-oxyl compounds such as hydroquinone, phenothiazine, t-butylcatechol, p-benzoquinone, hydroquinone monomethyl ether, methylene blue, diphenylamine, and 4-hydroxy-2,2,6,6-tetramethylpipericinooxyl are used alone. Or 2
It can be used as a mixture of more than one species.

In the embodiment shown in FIG. 2, an extraction column 14 is provided. Then, a mixture containing (meth) acrylic acid ester, unreacted alcohol, water and the like from the acid separation tower 2 is introduced into the extraction tower 14, and the oil phase obtained by extraction with water is separated into light boilers. Introduce into tower 3. The crude (meth) acrylate obtained in the light-boiling matter separation tower 3 is introduced into the rectification tower 4, and the product (meth) acrylate is recovered from the top of the tower. Then, the bottoms are circulated to, for example, the acid separation tower 2 or the light-boiling substances separation tower 3 to reuse the polymerization inhibitor in the bottoms.

The circulation position of the bottoms is the same as in the embodiment shown in FIG. 1 (except for the extraction column 14).
It can be circulated to any positions in the esterification step and the separation / purification step.

In the present invention, the bottom product from the rectification column 4 may be entirely circulated to the esterification step and / or the separation / purification step, or may be partially circulated.

[0017]

According to the method of the present invention, the polymerization inhibitor contained in the bottom of the rectification column can be effectively reused.
The production cost of the (meth) acrylate can be reduced. Further, since the residual (meth) acrylate in the bottom liquid can be effectively recovered, the (meth) acrylate can be produced in a high yield.

[0018]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples.

Example 1 According to the system diagram shown in FIG. 1, butyl acrylate was produced. 0.15 kg / h of acrylic acid containing 0.1% by weight of phenothiazine as a polymerization inhibitor, 0.16 kg / h of n-butanol, and a high-boiling substance separation column into which a bottom liquid of the acid separation column 2 and a part thereof are introduced. 5 with the overhead liquid,
56.2% by weight of butyl acrylate, 25.3% of acrylic acid
A strongly acidic cation exchange resin was charged using 1.34 kg / h of a liquid containing 8.4% by weight of a high-boiling substance containing 8.4% by weight of n-butanol, 7.1% by weight of n-butanol, 2.0% by weight of water, and phenothiazine as a catalyst. The recovered liquid containing n-butanol, which was introduced into the esterification reactor 1 made of glass and collected from the top of the light-boiling substance separation column 3, was subjected to a distillation column (Dickson packing packing column) attached to the esterification reactor 1. Was introduced. While removing water produced by the reaction from the top of the column, 60.2% by weight of butyl acrylate, 20.0% by weight of acrylic acid, 9.4% by weight of n-butanol, and 2.
1.70 kg / h of a reaction solution containing 3% by weight and 8.1% by weight of a high-boiling substance containing phenothiazine was obtained.

This reaction solution is introduced into the bottom of the acid separation column 2 of an old-shaw distillation column (all stages 20) made of glass and having an inner diameter of 50 mm. , N-butanol and water were distilled off. At this time, in order to prevent polymerization in the acid separation column 2, phenothiazine was dissolved in the reflux solution at 5 g / h and introduced.

Next, the distillate from the acid separation column 2 is separated into oil and water by an oil / water separator 6 attached to the acid separation column 2 and the oil phase is made of glass and has an inner diameter of 32 mm and an Oldershaw type distillation column (all stages). 2
Introduced into the sixth stage from the top of the light-boiling substance separation column 3 in 0). Butyl acrylate 7 recovered from the top of the light boiler separation tower 3
6.1% by weight, 13.3% by weight of n-butanol, water 1
0.08 kg / h of the 0.6% by weight liquid was returned to the distillation column attached to the esterification reactor 1, and 0.26 kg of crude n-butanol-free crude butyl acrylate was recovered from the bottom of the column.
/ H was withdrawn and introduced into the bottom of the rectification column 4. On this occasion,
In order to prevent polymerization in the light-boiling substance separation column 3, 1 g / h of phenothiazine was dissolved and introduced into the reflux liquid.

From the bottom of the acid separation tower 2, 55.8% by weight of butyl acrylate, 25.1% by weight of acrylic acid, 7.0% by weight of n-butanol, 2.0% by weight of water and 2.0% by weight of phenothiazine 1.36 kg of a liquid having a boiling weight of 10.1%
/ H, a part of it is introduced into the top of a high-boiling substance separation column 5 of an Oldershaw-type distillation column (all stages 5) made of glass and having an inner diameter of 32 mm, and high-boiling substances are discarded from the bottom of the column and distilled. The liquid was returned to the esterification reactor 1 together with the remaining bottom liquid from the acid separation column 2.

In order to prevent polymerization, 1 g of hydroquinone monomethyl ether was added to the rectification column 5 of an old-shaw distillation column (all stages 10) made of glass and having an inner diameter of 32 mm to prevent polymerization.
h was dissolved in the reflux liquid and introduced, and 0.25 kg / h of butyl acrylate was obtained from the top of the tower. Butyl acrylate was recovered from the bottom, including phenothiazine and hydroquinone monomethyl ether brought in from the previous step. Analysis of the bottoms revealed that 97% of the phenothiazine charged and 99% of the hydroquinone monomethyl ether remained, and were reused as stabilizers in the acid separation tower 2 and the light boiler separation tower 3.

Example 2 Methyl acrylate was produced according to the system diagram shown in FIG. To a stainless steel esterification reactor 1 filled with a strongly acidic cation exchange resin as a catalyst, 1.00 kg / h of acrylic acid, 0.43 kg / h of methanol and 0.43 kg / h of methanol were added with 0.1% by weight of hydroquinone as a polymerization inhibitor. Recovery liquid obtained by mixing the bottom liquid of the separation tower 2 and the top liquid of the high-boiling substance separation tower 5 into which a part thereof is introduced, and the alcohol recovery tower 13
10.8% by weight of methyl acrylate obtained by combining the recovery liquid containing methanol recovered from the top of
When 4.17 kg / h of a liquid containing 1.4 wt%, 13.8 wt% of methanol, 4.7 wt% of water, and 19.3 wt% of a high-boiling substance containing hydroquinone were introduced, the esterification reactor 1 At the outlet, a reaction liquid of 38.0% by weight of methyl acrylate, 27.5% by weight of acrylic acid, 3.6% by weight of methanol, 10.5% by weight of water, and 20.4% by weight of a high-boiling substance containing hydroquinone was obtained. Was.

This reaction solution is introduced into the bottom of the acid separation column 2 of an Oldershaw distillation column (all stages 20) made of glass and having an inner diameter of 50 mm, and methyl acrylate substantially containing no acrylic acid is introduced from the top of the column. 90.1% by weight, 3.3% by weight of methanol and 6.6% by weight of water were distilled at a rate of 3.93 kg / h. At this time, 2.5 g / h of hydroquinone was dissolved and introduced into the reflux liquid in order to prevent polymerization in the acid separation column 2. 13. methyl acrylate from the bottom of the acid separation tower 2;
8% by weight, acrylic acid 44.9% by weight, methanol 0.
A liquid of 83.4% by weight, 33.4% by weight of a high-boiling substance containing 7.0% by weight of water and hydroquinone was withdrawn at a rate of 2.55 kg / h, and a part thereof was made of glass and had an inner diameter of 32 mm, which was an Oldershaw distillation column ( The high-boiling substance is introduced into the top of the high-boiling substance separation column 5 in all stages 5), high-boiling substances are discarded from the bottom of the column, and the distillate is sent to the esterification reactor 1 together with the remaining bottom liquid from the acid separation column 2. I put it back.

Next, the distillate of the acid separation column 2 and the distillate of the light boiler separation column 3 containing 15.5% by weight of methyl acrylate, 4.5% by weight of methanol and 80.0% by weight of water. 0.
14 kg / h with an inner diameter of 100 mm was introduced into the Kuuni-type liquid-liquid extraction tower 14, extracted with 1.29 kg / h of water, and extracted with 96.7% by weight of methyl acrylate, 0.2% by weight of methanol,
An oil phase of 3.1% by weight of water was obtained at 3.59 kg / h. The aqueous phase is introduced into the alcohol recovery tower 13 and 0.24k from the top
Distilled at g / h, circulated to the esterification reactor 1, and part of the bottom liquid was reused as water introduced into the extraction column 14.

The oil phase obtained from the extraction column 14 is made of glass and has an inner diameter of 50 mm and is an old-shaw distillation column (all stages 20).
And the methanol and methyl acrylate are recovered from the top of the column at normal pressure and returned to the extraction column 14, and contain substantially no methanol obtained from the bottom of the column. Crude methyl acrylate is added to acid separation tower 2
Except that it is used as a reflux solution of 1.1 in the bottom of the rectification column 4.
Introduced at 4 kg / h. At this time, in order to prevent polymerization in the light boiler separation column 3, hydroquinone was added to the reflux liquid.
5 g / h was dissolved and introduced.

In order to prevent polymerization, 2.5 g / h of hydroquinone was dissolved in the reflux liquid and introduced into the rectification column 4 of an old-shaw distillation column (all stages 10) made of glass and having an inner diameter of 32 mm. Product methyl acrylate from 1.09
kg / h. From the column bottom, including the hydroquinone brought in from the previous step, it was recovered together with methyl acrylate. When this bottom liquid was analyzed, 98% of the charged hydroquinone remained, and was reused as a stabilizer for the acid separation column 2 and the light-boiling substance separation column 3.

[0029]

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of the method of the present invention.

FIG. 2 is a system diagram showing another embodiment. REFERENCE SIGNS LIST 1 esterification reactor 2 acid separation tower 3 light-boiling matter separation tower 4 rectification tower 5 high-boiling matter separation tower 6 oil-water separator 7 raw material alcohol 8 raw material acid 9 product 10 polymerization inhibitor-containing liquid (bottom liquid) 11 wastewater 12 Waste oil 13 Alcohol recovery tower 14 Extraction tower 15 Water

Claims (1)

[Claims] An esterification step of subjecting (meth) acrylic acid and an aliphatic alcohol having 1 to 4 carbon atoms to an esterification reaction in the presence of an acidic catalyst to produce a (meth) acrylic acid ester, and (meth) ) Separating and purifying the (meth) acrylate from the acrylate-containing mixture,
In a method for producing a (meth) acrylic acid ester through a separation / purification step including an acid separation tower, a light-boiling matter separation tower and a rectification tower, the bottom product of the rectification tower is esterified and / or separated. A method for producing a (meth) acrylic ester, wherein the method is circulated to a purification step.