KR20120031040A - Process for preparing alkyl (meth)acrylate - Google Patents

Abstract

PURPOSE: A manufacturing method of alkyl(meth)acrylate is provided to have high recycle and reuse rate of a catalyst, to prevent pipe clogging phenomenon, and to the amount of reduce waste catalyst. CONSTITUTION: A manufacturing method of alkyl(meth)acrylate comprises: a step of esterification reacting a reactant comprising (meth)acrylic acid and alkanol under the presence of organic acidic catalyst; a step of purifying the reaction product in a distillation column in which a heat flow reboiler is equipped in bottom; a step of collecting top discharge liquid containing alkyl(meth)acrylate and water in the top of the distillation column, and collecting bottom discharge liquid containing addition product with high boiling point and water in the bottom of the distillation column; and a step of recirculating the separated water for re-using for the esterification.

Description

Production method of alkyl (meth) acrylate {PROCESS FOR PREPARING ALKYL (METH) ACRYLATE}

The present invention relates to a process for producing alkyl (meth) acrylates.

Generally alkyl (meth) acrylates are prepared via esterification of (meth) acrylic acid with alkanols in the presence of an acid catalyst. Since the esterification reaction is an equilibrium reaction, by removing the generated water out of the reactor, the reaction equilibrium can be shifted to the forward reaction to increase the conversion to alkyl (meth) acrylate.

As the acid catalyst used in the esterification reaction, inorganic acids such as sulfuric acid, organic acids such as alkanesulfonic acid, and ion exchange resins are generally used.

Since sulfuric acid is used as a catalyst, it is highly corrosive, so the wall of the reactor should be treated with a corrosion resistant material, and the esterification reaction should be carried out using a batch reactor rather than a continuous reactor, and neutralized with a basic substance after the reaction is completed. The catalyst must be removed in such a way that, in this case, a large amount of water is required, thereby increasing the cost of wastewater treatment.

On the other hand, when the ion exchange resin is used as a catalyst, since the activity of the catalyst is generally drastically decreased at a temperature of 90 ° C. or higher, the reaction temperature cannot be increased to 90 ° C. or higher, and thus the reaction is performed at a relatively low temperature. The reaction rate is lowered and the conversion rate of the overall reaction is lowered. As a result, the amount of recycled unreacted materials to the reactor is increased, thereby reducing process efficiency and reducing productivity, such as the need to periodically replace the catalyst.

On the other hand, when the organic acid is used as a catalyst, since the corrosiveness is lower than that of the inorganic acid catalyst such as sulfuric acid, reactors or columns of various materials can be used, and the purification process can be continuously performed without additional salt treatment after the reaction.

However, the price of organic acid catalyst is several times to several tens of times higher than that of inorganic acid catalyst such as sulfuric acid, which increases the manufacturing cost. In addition, when an organic acid is used as a catalyst, the catalyst is mixed with a high boiling point adduct, which is a side reaction product of an esterification reaction, to generate a tar-like material, which is deposited on a wall of a heat exchanger such as a reactor or a distillation column to hinder heat exchange. High boiling point adduct decomposition may cause pipe blockage in the reactor.

In addition, some of the organic acid catalyst is discharged into the waste oil together with the heavy material. Since the amount of the catalyst has to be replenished into the esterification reactor, it is necessary to minimize the amount of the emitted catalyst. In addition, the waste oil is incinerated to recover some of the energy with steam. Waste oil containing an organic acid catalyst may cause environmental problems during incineration, and thus, pretreatment such as salt treatment should be performed before incineration, and sulfuric acid may be incinerated. There are problems such as the need to handle the cargo separately.

Accordingly, various studies have been made on how to increase the recovery and reuse rate of the organic acid catalyst and reduce the amount of the organic acid catalyst finally discarded in the process of preparing alkyl (meth) acrylate, but the degree is still insufficient. It is true.

The present invention provides a method for producing an alkyl (meth) acrylate using an organic acid catalyst, while increasing the recovery and reuse rate of the catalyst, it is possible to prevent the blockage of the pipe in the high boiling point addition product decomposition reactor, and finally discarded catalyst It provides a method for producing an alkyl (meth) acrylate that can reduce the amount of.

The present invention

Esterifying the reactant comprising (meth) acrylic acid and alkanol with conversion of at least 70% in the presence of an organic acid catalyst;

Supplying and purifying the reaction product of the esterification reaction to a distillation column having a heat flow reboiler at the bottom;

Recovering an upper effluent including alkyl (meth) acrylate and water in the upper part of the distillation column, and recovering a lower effluent including high boiling point adduct and water in the lower part of the distillation column;

Separating the bottom discharge liquid of the distillation column into a water layer and an organic layer; And

Recycling the water layer separated from the bottom effluent to be used in the esterification reaction, wherein each step occurs continuously,

The water contained in the bottom discharge liquid of the distillation column provides a method for producing alkyl (meth) acrylate is 2 to 25% by weight based on the total weight of the discharge liquid.

The method of preparing the alkyl (meth) acrylate may further include supplying 1.01 to 1.20 times of water from the top of the distillation column relative to the weight of water contained in the discharge liquid discharged to the top of the distillation column.

In addition, the pressure of the top of the distillation column and the temperature of the liquid in the heat flow supply unit are 130 Torr or more and less than 170 Torr and 65 to 90 ℃, respectively; 170 Torr or more and less than 200 Torr and 70 to 95 ° C; Or 200 Torr or more and less than 230 Torr and 75 to 100 ° C.

In addition, the method of producing the alkyl (meth) acrylate is the pressure of the top of the distillation column and the temperature of the liquid in the heat flow supply unit is 130 Torr or more and less than 170 Torr and 65 to 90 ℃, 170 Torr or more and less than 200 Torr and 70 to 95, respectively Or 200 Torr or more and less than 230 Torr and 120 to 140 ° C; The method may further include supplying 1.01 to 1.20 times the amount of water from the top of the distillation column relative to the weight of the water contained in the discharge liquid discharged to the top of the distillation column.

In addition, the water layer separated from the bottom discharge of the distillation column may include at least 50% by weight of the organic acid catalyst supplied to the esterification reaction.

In addition, the manufacturing method according to the present invention may further include a step of supplying the organic layer separated from the bottom discharge of the distillation column to the high boiling point addition product decomposition reactor for the decomposition reaction.

The decomposition reaction may be carried out under the conditions of temperature 120 to 220 ℃, pressure 30 to 760 Torr. In this case, the residence time of the decomposition reaction is not limited in its configuration, but may be 1 to 40 hours residence time in consideration of the feed rate of the reactants.

In addition, the production method according to the present invention may further comprise the step of supplying a portion of the water layer separated from the bottom discharge of the distillation column to the high boiling point adduct decomposition reactor. In this case, the catalyst included in the decomposition reactor may be included in 0.01 to 5% by weight based on the total weight of the reaction solution supplied to the decomposition reactor.

In addition, the production method according to the present invention may further comprise the step of recycling the top discharge of the decomposition reaction to the esterification step. Or recycling the upper effluent of the decomposition reaction to the purification step of the esterification reaction product.

In addition, the catalyst contained in the bottom discharge liquid of the high boiling point adduct decomposition product may be 10% by weight or less based on the total weight of the bottom discharge liquid.

On the other hand, the esterification reaction can be carried out in one or more continuous reactors connected in series. At this time, it may further include a water separation tower for purifying the water discharged from the top of each of the continuous reactor.

In addition, the esterification reaction may be carried out under the conditions of temperature 70 to 150 ℃ and pressure 50 to 760 Torr.

The molar ratio of alkanol to (meth) acrylic acid included in the reactant in the esterification step may be 1.05 to 5. In addition, the content of the organic acid catalyst in the esterification step may be 0.01 to 5% by weight based on the total weight of the reactant.

On the other hand, the alkanol may be an alkanol having 4 to 8 carbon atoms.

In addition, the organic acid catalyst may be at least one selected from the group consisting of alkanesulfonic acid and arylsulfonic acid.

The method for preparing alkyl (meth) acrylate according to the present invention, while having a high recovery and reuse rate of the catalyst, can secure the fluidity in the high-boiling addition product decomposition reactor to prevent pipe blockage, and finally There is an advantage to reduce the amount.

1 is a process diagram schematically showing a manufacturing process of an alkyl (meth) acrylate according to an embodiment of the present invention.

Hereinafter, a method for preparing alkyl (meth) acrylate according to embodiments of the present invention will be described.

Prior to this, unless otherwise stated throughout the specification, '(meth) acrylic acid' is defined as collectively acrylic acid or methacrylic acid; 'Alkyl (meth) acrylate' is defined as collectively referred to as alkyl acrylate or alkyl methacrylate.

In addition, the term 'reactant' is defined as including a mixture of (meth) acrylic acid and alkanol for the esterification reaction; 'Conversion rate' refers to the reaction amount expressed as a percentage of the supply of the limiting reactant (limiting reactant) of the reactants.

In addition, the 'reaction product' is defined as including an adduct, an unreacted reactant, a catalyst, and the like, in addition to the alkyl (meth) acrylate produced after the esterification reaction.

In addition, the term 'high boiling materials' refers to a mixture of reactants and products, or adducts produced by Michael reaction (Michael reaction) between reactants. It means a material that is higher than the alkyl (meth) acrylate.

In addition, the term 'heavies' refers to a mixture of the high boiling point adduct, the catalyst used in the alkyl (meth) acrylate manufacturing process, the polymerization inhibitor and other polymers.

The inventors of the present invention, in the course of studying the method for producing alkyl (meth) acrylate, the alkyl (meth) acrylate azeotrope with the alkanol and water in the step of purifying the esterification reaction product to the distillation column By using, the amount of water in the reflux supplied to the top of the distillation column is supplied more than the amount of water recovered from the top of the distillation column, or the temperature of the liquid in the heat flow supply of the distillation column according to the pressure range of the distillation column in the purification step to a specific range Or, if the two conditions are satisfied at the same time, the amount of water contained in the bottom discharge liquid of the distillation column can be adjusted to a specific range, so that the bottom discharge liquid can be easily separated into the water layer and the organic layer, By effectively recovering the organic acid catalyst included in the water layer, it is possible to minimize the waste of the catalyst, In addition, the present invention was completed by confirming that it is possible to prevent the blockage of the pipe by securing fluidity in the high-boiling addition product decomposition reactor.

Such the present invention, according to one embodiment,

Esterifying the reactant comprising (meth) acrylic acid and alkanol with conversion of at least 70% in the presence of an organic acid catalyst;

Supplying and purifying the reaction product of the esterification reaction to a distillation column having a heat flow reboiler at the bottom;

Recovering an upper effluent including alkyl (meth) acrylate and water at the top of the distillation column, and recovering an effluent including high boiling point adduct and water at the bottom of the distillation column;

Separating the bottom discharge liquid of the distillation column into a water layer and an organic layer; And

Recycling the water layer separated from the bottom effluent to be used in the esterification reaction, wherein each step occurs continuously,

The water contained in the bottom discharge liquid of the distillation column provides a method for producing alkyl (meth) acrylate of 2 to 25% by weight based on the total weight of the discharge liquid.

Hereinafter, each step that may be included in the method for preparing alkyl (meth) acrylate according to the present invention will be described in more detail.

First, a method of preparing an alkyl (meth) acrylate according to an embodiment of the present invention comprises the steps of esterifying a reactant comprising (meth) acrylic acid and an alkanol in the presence of an organic acid catalyst (hereinafter 'esterification step' It includes).

The esterification step is an esterification reaction of (meth) acrylic acid and alkanol as a reactant, and may be performed in the presence of an organic acid catalyst, and the reaction product according to the step may include alkyl (the desired product). Meth) acrylate and by-product water (H ₂ O) is mainly included, in addition to unreacted and side reaction products may be included.

In the present invention, the esterification step may be performed under conventional apparatus and conditions in the art to which the present invention pertains, except that the conversion rate of the defined reactants in the reactants is 70% or more.

In this case, the conversion rate may be defined as in Formula 1 below, the conversion rate is 70% or more, preferably 90% or more, more preferably in order to increase the productivity by generating as much alkyl (meth) acrylate by the esterification reaction as much as possible Preferably from 95 to 99.9%. The conversion can be confirmed using a conventional method such as a gas chromatograph.

[Calculation 1]

The (meth) acrylic acid in the reactants is not particularly limited because it can be used in the art.

In addition, the alkanol of the reactants can be appropriately selected and used according to the desired (meth) acrylate, but the configuration thereof is not particularly limited, but alkanols having 4 to 8 carbon atoms are preferred, and more preferably n-butanol, It may be at least one selected from the group consisting of i-butanol, t-butanol, n-pentanol, t-amyl alcohol, n-hexanol, n-heptanol, n-octanol and 2-ethylhexyl alcohol. .

In this case, the ratio of (meth) acrylic acid and alkanol in the esterification reactor may be determined in various ranges in consideration of reaction efficiency, preferably 1.05 to 5 moles of alkanol per 1 mole of (meth) acrylic acid, more preferably May be used in a ratio of 1.05 to 3 moles. That is, the esterification reaction of (meth) acrylic acid and alkanol is an equilibrium reaction, and in the case of a continuous manufacturing process, water (H ₂ O) is continuously removed from the reaction product and excess of (meth) acrylic acid or alkanol as a starting material is used. It is advantageous to continuously prepare the (meth) acrylate.

In addition, the organic acid catalyst used in the above step may use a conventional organic acid catalyst that can be used in the esterification reaction in the art, preferably one or more selected from the group consisting of alkanesulfonic acid and arylsulfonic acid. It may be more preferably one or more selected from the group consisting of methane sulfonic acid, benzene sulfonic acid, para toluene sulfonic acid and linear alkylbenzene sulfonic acid.

The content of the organic acid catalyst may be appropriately determined according to the kind of reactants used or the kind of catalyst, but preferably 0.1 to 5 wt% or more, and more preferably 0.1 to 3 wt% of the catalyst, based on the reactant. have.

On the other hand, a polymerization inhibitor may be used for the purpose of preventing the polymerization of the reactant (meth) acrylic acid and the product alkyl (meth) acrylate. Under the present circumstances, the said polymerization inhibitor is not specifically limited, Any thing can be used as long as it has a polymerization prevention effect with respect to (meth) acrylic acid and alkyl (meth) acrylate. Preferably, the polymerization inhibitor is a phenol-based compound including hydroquinone, paramethoxy phenol and the like; Phenothiazine, N-phenyl-N'-isopropyl paraphenylene diamine, N, N'-di-2-naphthyl paraphenylene diamine, N-phenyl-N '-(1,3-dimethylbutyl) para Amine compounds including phenylene diamine and the like; 4-hydroxy-2,2,6,6-tetramethyl piperidine-N-oxyl, 4-benzoyloxy-2,2,6,6, -tetramethyl piperidine-N-oxyl, 4-acetyl N-oxyl-based compounds including amino-2,2,6,6, -tetramethyl piperidine-N-oxyl and the like.

The amount of the polymerization inhibitor may be appropriately determined depending on the kind of the reactant used or the type of the polymerization inhibitor, but may preferably be included as 0.01 to 1% by weight based on the total weight of the resulting alkyl (meth) acrylate. More preferably 0.05 to 0.5% by weight.

In addition, the esterification reaction can be carried out under reaction conditions commonly applied in the art to which the present invention belongs, in order to achieve a more efficient reaction, the reaction temperature of 70 to 150 ℃, preferably 70 to 130 ℃, more Preferably it may be carried out at 80 to 120 ℃. The pressure may be determined in the range of 50 to 760 Torr at a pressure capable of continuously removing water generated at each reaction temperature.

In this case, as a reactor for performing the esterification step, a continuous stirred-tank reactor conventional in the art may be used in consideration of manufacturing efficiency. In addition, such a continuous reactor may be one or more connected in series for efficient process management. In this case, in order to move the reaction equilibrium toward the forward reaction by removing the water produced as a by-product from the esterification reaction, it is preferable to remove the water through each upper portion of the continuous reactor, the water separation tower is added to the reactor top It can be provided as.

1 is a process diagram schematically showing a process for preparing an alkyl (meth) acrylate according to an embodiment of the present invention, for example with reference to this esterification step, the esterification reaction is connected in series 2 Can be carried out in two continuous reactors (R1 and R2).

The first reactor (R1) is a pre-reactor, (meth) acrylic acid, alkanol and catalyst can be continuously supplied through the first to third flows, the residence time of the reactants 0.1 to The preliminary reaction may be performed such that the conversion rate of the limited reactant is about 20 to 80% for 2 hours. In addition, in the second reactor (R2), the first conversion (R1) followed by the residence time of the reactants 1 to 3 hours, the final conversion of the reactant is at least 70%, preferably at least 90%, more preferably 95 to 99.9% The esterification reaction may proceed to be.

At this time, the water may be removed through the upper portion of each of the continuous reactors (R1 and R2), and azeotropically discharged together with water, alkanol, alkyl (meth) acrylate in the upper portion of the water separation tower (D) The upper discharge liquid is separated into a water layer and an organic layer in a decanter and receiver (T1), and the water layer may include a part of alkanol. The organic layer may be recycled to the first reactor (R1), and the water layer may be recovered to a decanter and receiver (T3) connected to the distillation column (D2) of the purification step to be described later, and used as a reflux solution of the purification step.

However, the present invention is not limited by the example of FIG. 1 described above, and in order to optimize the reaction process by controlling the conversion rate of the limited reactants in a series of continuous reactors connected in series, reaction temperature, type and amount of catalysts , The residence time (or reactor volume) of the reactants and reaction products, the type of reactor, and the like can be variously designed.

On the other hand, in the production method according to the present invention, after the esterification step, it is possible to perform the step of purifying the reaction product of the esterification reaction by supplying to the distillation column (hereinafter referred to as "purification step").

The purification step is a step for separating the desired product alkyl (meth) acrylate from the reaction product of the aforementioned esterification step by distillation.

At this time, the distillation column in the purification step may be used in the art to which the present invention belongs. Preferably, the distillation column may be provided with a heat flow supply (reboiler) at the bottom, the shape of the heat flow supply (reboiler) is that of the conventional form in the art to which the present invention belongs, such as Kettle type, Shell and Tube type. Can be. In addition, the distillation column may use a tray-type or downcomer-type tower such as a charging tower, an alder show, a lift tray, or the like, filled with a filler such as Hereypak, Magmahorn, and Cascade mini-ring. In addition, the number of theoretical stages of the distillation column is preferably 20 or more stages in view of separation ability, efficiency, and the like, and may be 60 or less stages in view of low pressure difference.

In particular, in the present invention, in order to ensure that the amount of water included in the bottom discharge of the distillation column in a recovery step which is continued with the refining step is included in a specific content according to the present invention, i) added as reflux in the refining step Adjusting the amount of water to be made; Ii) adjusting the amount of heat supplied to the heat flow reboiler provided in the lower portion of the distillation column according to the pressure range of the upper part of the distillation column to adjust the temperature of the liquid in the heat flow supply to a specific range; Or iii) a method of adjusting to satisfy the two conditions at the same time.

Specifically, iii) the method for adjusting the amount of water added to the reflux in the purification step, the step of supplying 1.01 to 1.20 times the water in the top of the distillation column relative to the weight of the water contained in the discharge liquid discharged to the top of the distillation column It can be carried out by a method further comprising. At this time, the amount of water supplied from the top of the distillation column may be performed to be 1.01 to 1.20 times, preferably 1.01 to 1.15 times, more preferably 1.01 to 1.10 times the weight of the water contained in the discharge liquid discharged to the top of the distillation column. have.

That is, in the purification step, water, alkanol, and alkyl (meth) acrylate are discharged to form an azeotrope with a specific composition at an operating pressure, and the flow rate of water can be known through the flow rate discharged to the top of the distillation column. The amount of water added to the reflux from the total amount discharged to the top of the distillation column may be adjusted to fall within the above range. For example, when the content of water in the azeotropic composition at the top of the distillation column is 40% by weight, the amount of water added as reflux can be adjusted to be 40.4 to 48% by weight of the total flow rate discharged to the top of the column.

In addition, ii) the method for adjusting the temperature of the liquid in the heat flow supply unit according to the pressure range of the upper part of the distillation column, the pressure of the top of the distillation column and the temperature of the liquid in the heat flow supply unit in the refining step, respectively 130 Torr or less than 170 Torr and 65 to 90 ° C; 170 Torr or more and less than 200 Torr and 70 to 95 ° C; Or 200 Torr or less and less than 230 Torr and 75 to 100 ° C.

Further, iii) the amount of water added to the reflux can be adjusted to the above range, and the temperature of the liquid in the heat flow supply can be adjusted to the above range according to the pressure range of the upper part of the distillation column.

As such, the content of the water contained in the bottom discharge liquid of the distillation column through the above method can be adjusted to the content range according to the present invention, thereby separating the bottom discharge liquid of the distillation column into a water layer and an organic layer to achieve the object of the present invention. You can do it. This will be described later.

Referring to FIG. 1, an example of the purification step will be described. The reaction product prepared in the above-described esterification step is supplied to a distillation column (D2), and the supplied reaction product is a hot stream provided at the bottom of the distillation column (D2). Distillation is carried out for a certain period of time in the feed. In this case, a reflux solution including water may be supplied to the upper portion of the distillation column D2 through the decanter and the receiver T3. However, the present invention is not limited to the examples described above.

On the other hand, the production method according to the invention, after the purification step, recovering the upper effluent containing the alkyl (meth) acrylate, alkanol and water at the top of the distillation column, and adding a high boiling point at the bottom of the distillation column A step of recovering the bottoms effluent including heavy substances such as a product, (meth) acrylic acid, alkanol, alkyl (meth) acrylate and water may be performed.

In general, the alkyl (meth) acrylate is recovered at the top of the distillation column azeotropic with water and alkanol, and further water and alkanol as reflux to recover the alkyl (meth) acrylate to the top of the column. It can be put in.

Alkyl (meth) acrylate, alkanol and water recovered to the top of the distillation column in the purification step may be separated through an additional distillation apparatus, respectively, through which a high purity alkyl (meth) acrylate may be obtained. At this time, the separated water and alkanol may be recycled to the esterification step or purification step.

Meanwhile, in the purification step, mainly unreacted (meth) acrylic acid, an organic acid catalyst, a polymerization inhibitor, water, and a high boiling point adduct are mixed and recovered as the lower part of the distillation column, and alkyl (meth) which is not discharged to the top of the distillation column is recovered. ) Acrylates and alkanols, and the like. The bottom discharge of the distillation column is recycled back to the esterification step.

Here, the high boiling point adducts, as defined above, are mainly adducts produced by the Michael reaction (Michael reaction) between the reactants and the product, or are reacted with alkyl (meth) acrylates. High molecular weight, high boiling point, can be decomposed under high heat and acid catalyst to reuse the decomposition products. Representative examples of the high boiling point adducts that may be produced in the manufacturing process of butyl acrylate in alkyl (meth) acrylate include β-butoxypropionic acid (C ₄ H ₉ OCH ₂ CH ₂ COOH) , n-Butyl diacrylate, CH ₂ CHCOOCH ₂ CH ₂ COOC ₄ H ₉ , Butyl-β-Butoxypropionate, C ₄ H ₉ OCH ₂ CH ₂ COOC _4, there may be mentioned H ₉₎ or the like.

In particular, according to the present invention, the amount of water contained in the bottom discharge liquid of the distillation column is 2 to 25% by weight, preferably 3 to 20% by weight, and more preferably 3 to 15% by weight, based on the total weight of the bottom discharge liquid. Is advantageously maintained. That is, when the amount of water included in the bottom discharge liquid of the distillation column satisfies the above range, the bottom discharge liquid of the distillation column may be separated into the water layer and the organic layer in the subsequent step, so that the recovery of the organic acid catalyst used in the reaction It can be done easily. More details about this will be described later.

On the other hand, the production method according to the present invention, after the recovery step, the step of separating the bottom discharge liquid of the distillation column into a water layer and an organic layer; And recycling the water layer separated from the bottom discharge liquid to be used in the esterification reaction.

The bottom discharge of the distillation column contains heavy substances such as high boiling point adducts, catalysts, polymerization inhibitors, etc., and when it is recycled to the esterification step as it is, the heavy substances accumulate and the heat exchanger or pipe of the reactor or distillation column is accumulated. Problems such as depositing on can occur. Therefore, a certain amount should be discharged out of the system so that the heavy material does not accumulate.

In general, the previous alkyl (meth) acrylate manufacturing process has a separate process of cracking a high boiling point adduct of the heavy material by removing a predetermined amount from the bottom discharge of the distillation column, and the high boiling point adduct is an organic acid. When hydrolyzed or thermally decomposed in the presence of a catalyst, it may be recovered as (meth) acrylic acid, alkanol or alkyl (meth) acrylate, or the like.

However, in the process of decomposing the high boiling point adduct, the organic acid catalyst is discharged and disposed together with the heavy material as waste oil. Here, the amount of the organic acid catalyst discharged is not only supplemented to the esterification reactor, but also the organic acid catalyst. Since waste oil containing a large amount of waste may cause serious environmental pollution problems, it is necessary to minimize the amount of catalyst discharged into the waste oil while maintaining the minimum amount of catalyst required for the decomposition of high-boiling side products. have.

However, in the conventional general alkyl (meth) acrylate manufacturing process, the amount of catalyst discharged along with the waste oil is large, requiring a large amount of expensive organic acid catalyst, and thus there is a problem in that the manufacturing efficiency is lowered.

In view of this, the present inventors add 알킬) alkyl (meth) acrylate as a reflux in azeotrope with water and alkanol to discharge to the top of the distillation column in the step of purifying and supplying the esterification reaction product to the distillation column. Or ii) adjusting the temperature of the liquid in the heat flow supply in accordance with the pressure range of the top of the distillation column in the refining step, or iii) adjusting to satisfy both of the above conditions at the same time. The amount of water included can be adjusted, through which the lower effluent can be easily separated into the water layer and the organic layer, confirming that the organic acid catalyst contained in the water layer can be effectively recovered and reused to complete the present invention. .

* That is, the production method according to the present invention is adjusted to satisfy the conditions of i), ii) or iii) described above in the refining step, so that the amount of water contained in the bottom discharge liquid of the distillation column is the total weight of the bottom discharge liquid. 2 to 25% by weight, preferably 3 to 20% by weight, more preferably 3 to 15% by weight can be maintained.

In other words, in order to allow the bottom discharge liquid of the distillation column to be separated into the water layer and the organic layer, the amount of water included in the bottom discharge liquid of the distillation column is preferably 2% by weight or more based on the total weight of the bottom discharge liquid.

That is, when the amount of water contained in the bottom of the distillation column is less than 2% by weight based on the total weight of the bottom of the discharge liquid, the bottom discharge liquid may not be separated into the water layer and the organic layer, or separated according to the type of organic acid catalyst to be used. Even if the amount of the organic acid catalyst may be included in the water layer is not enough recovery amount of the catalyst, which leads to a problem that the amount of catalyst discarded in the high-boiling addition reaction cracking reactor increases. For example, when the amount of water included in the bottom discharge liquid of the distillation column is less than 2% by weight based on the total weight of the bottom discharge liquid, when the paratoluene sulfonic acid is used as the organic acid catalyst, the bottom discharge liquid is the water layer and the organic layer. Cannot be separated. In addition, when methane sulfonic acid or benzene sulfonic acid is used as the organic acid catalyst, the bottom discharge liquid may be separated into the water layer and the organic layer, but the amount of the catalyst that may be included in the water layer is supplied to the esterification reaction. May be less than 50% by weight, resulting in insufficient recovery of the catalyst.

In addition, when excess water is refluxed in the upper part of the distillation column or the temperature of the liquid in the heat flow supply part is lowered more than necessary according to the pressure range of the upper part of the distillation column, the content of water in the lower part of the distillation column bottom is increased to be treated in the reactor. Since the amount of water increases, which causes an increase in energy cost and a decrease in reaction rate, the amount of water included in the bottom discharge of the distillation column is preferably 25% by weight or less based on the total weight of the bottom discharge. Do.

As such, by adjusting the amount of water contained in the bottom discharge liquid of the distillation column, the bottom discharge liquid of the distillation column may be separated into a water layer and an organic layer, and in the separated water layer, most of the organic acid catalyst used in the esterification reaction is exist. That is, methane sulfonic acid and benzene sulfonic acid are known to have almost infinite solubility in water, and paratoluene sulfonic acid, which is another example, has a high solubility of 67 g per 100 ml of water. Easily soluble in the water layer in the liquid. In addition, since the organic acid catalyst has a relatively high specific gravity compared to the bottom discharge of the distillation column, almost all of the organic acid catalyst can be easily dissolved in the water layer even with a short residence time.

Accordingly, the water layer separated from the bottom discharge of the distillation column may contain at least 50% by weight, preferably at least 60% by weight, more preferably 70 to 99% by weight of the organic acid catalyst supplied to the esterification reaction. Can be.

Separating the bottom discharge of the distillation column into a water layer and an organic layer, as illustrated in Figure 1, may be made in a separate decanter and receiver (T2), where the separated water layer is recycled to the esterification step ( 10 times). Through this, the production method according to the present invention can easily recover the organic acid catalyst before the decomposition reaction step of the high-boiling addition product, which will be described later, to minimize the amount of the discarded catalyst, which is generated from the discarded catalyst Environmental problems can be reduced, and pipe clogging due to slurry generation can be alleviated, resulting in stable process operation.

On the other hand, the production method according to the present invention may further include a step of decomposition reaction by supplying the organic layer separated from the bottom discharge of the distillation column to the high boiling point addition product decomposition reactor.

The organic layer separated from the bottom effluent of the distillation column contains most of the high boiling point adducts. The high boiling point adducts are hydrolyzed or thermally decomposed in the presence of an organic acid catalyst in a separate decomposition reactor to form alkyl (meth) acrylates. , Alkanol, (meth) acrylic acid, and the like, and undecomposed high-boiling adducts and heavy substances such as polymerization inhibitors and organic acid catalysts can be discharged and disposed of.

In this case, the entire organic layer separated from the bottom discharge of the distillation column may be supplied to the high boiling point addition product decomposition reactor, or 5 to 50 wt%, preferably 5 to 40 wt% of the organic layer in consideration of the efficiency of the continuous process. %, More preferably 5 to 30% by weight may be fed to the high boiling point adduct decomposition reactor for decomposition reaction, and the remainder may be recycled to the esterification step.

On the other hand, the decomposition reaction of the high boiling point addition product in consideration of the efficiency of the decomposition reaction temperature 120 to 220 ℃, preferably 120 to 200 ℃, more preferably 120 to 180 ℃; And residence time 1 to 40 hours, preferably 2 to 30 hours, more preferably 3 to 20 hours. At this time, the pressure in the high boiling point addition product decomposition reactor depends on the temperature, and the decomposition products (meth) acrylic acid, alkanol, alkyl (meth) acrylate, etc. can be maintained to the degree that can be recovered to the top of the reactor, preferably Preferably from 30 to 760 Torr.

In addition, the decomposition reaction of the high boiling point adduct may be further promoted in the presence of an acid catalyst. Therefore, the manufacturing method according to the present invention may further include supplying a portion of the water layer separated from the bottom discharge of the distillation column to the high boiling point adduct decomposition reactor.

That is, since the water layer separated from the bottom discharge of the distillation column contains a large amount of the organic acid catalyst, it can be further promoted the decomposition reaction of heavy materials by supplying it to the high boiling point addition product decomposition reactor.

In this case, the amount of the catalyst included in the high boiling point addition product decomposition reactor is 0.01 to 5 weight based on the total weight of the reaction liquid supplied to the decomposition reactor (that is, the total weight of the organic layer supplied into the high boiling point addition product decomposition reactor). %, Preferably 0.05 to 3% by weight, more preferably 0.1 to 2% by weight, thereby promoting decomposition reaction of the high boiling point adduct and ensuring fluidity in the decomposition reactor to prevent pipe blockage. At the same time, it is possible to minimize the amount of catalyst discarded.

Here, the method of supplying a portion of the water layer separated from the bottom discharge of the distillation column to the high boiling point addition product decomposition reactor, the water layer is continuously supplied or intermittently so that the concentration of the organic acid catalyst to satisfy the above range It can be used to supply the method.

As such, when the decomposition reaction step of the high boiling point addition product is performed, the upper effluent of the decomposition reactor may include alkyl (meth) acrylate, alkanol, (meth) acrylic acid, etc. due to decomposition of the high boiling point addition product. This may be recycled to the esterification step or purification step of the esterification product.

That is, the production method according to the present invention may further comprise the step of recycling the top discharge of the decomposition reactor to the esterification step, or, the purification of the esterification reaction product of the top discharge of the decomposition reactor It may also include recycling to the step.

On the other hand, the lower discharge of the decomposition reactor may be mixed with an organic acid catalyst and undecomposed heavy materials such as tar component.

In the previous method for preparing alkyl (meth) acrylate, the amount of catalyst contained in the lower discharge of the decomposition reactor is discarded, so that a large amount of expensive organic acid catalyst is required, resulting in low production efficiency, and containing a large amount of organic acid catalyst. In the process of disposing waste oil, there was a problem causing serious environmental pollution.

However, as described above, the production method according to the present invention has an advantage of minimizing the amount of the catalyst discarded as it effectively recovers most of the organic acid catalyst before the decomposition reaction step of the high boiling point adduct. That is, in the production method according to the present invention, the amount of catalyst contained in the bottom discharge liquid of the high boiling point addition product decomposition reactor is 10% by weight or less, preferably 5% by weight or less, based on the total weight of the bottom discharge liquid. Preferably there is an advantage of 1 to 5% by weight.

According to one embodiment of the present invention, in the decomposition reaction step of the high boiling point addition product, as illustrated in FIG. 1, the organic layer separated from the decanter and the receiver T2 is supplied to the high boiling point addition product decomposition reactor R3. The top effluent of the decomposition reactor R3 may be recycled to the esterification reactor R1 (flow 12) or recycled to the distillation column D2 (not shown). In this case, in order to promote the decomposition reaction, a portion of the water layer separated from the decanter and the receiver T2 may be supplied to the decomposition reactor R3. In addition, the bottom discharge liquid of the decomposition reactor (R3) may be disposed of as waste oil (flow 13).

As such, the method for producing an alkyl (meth) acrylate according to the present invention

Esterifying the reactant comprising (meth) acrylic acid and alkanol with conversion of at least 70% in the presence of an organic acid catalyst; Supplying and purifying the reaction product of the esterification reaction to a distillation column having a heat flow reboiler at the bottom; Recovering an upper effluent including alkyl (meth) acrylate and water in the upper part of the distillation column, and recovering a lower effluent including high boiling point adduct and water in the lower part of the distillation column; Separating the bottom discharge liquid of the distillation column into a water layer and an organic layer; And recycling the water layer separated from the bottom effluent for use in the esterification reaction, wherein each step occurs continuously, and the amount of water contained in the bottom effluent of the distillation column is the total amount of the bottom effluent. It can be carried out by a method such that 2 to 25% by weight relative to the weight is maintained.

However, in addition to the above-described steps, it may further include a step that can be conventionally performed in the art before or after each of the above steps, the manufacturing method of the present invention is limited by the above steps It doesn't happen.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments are described to facilitate understanding of the present invention. However, the following examples are intended to illustrate the present invention without limiting it thereto.

In particular, the following examples describe the production method of butyl acrylate, but the production method of the present invention is not limited thereto, and is produced by esterification using (meth) acrylic acid and alkanol having 4 to 8 carbon atoms. It is equally applicable to the manufacturing method of the alkyl (meth) acrylate which becomes.

Comparative example  One

Butyl acrylate was prepared from the target material of alkyl (meth) acrylate.

To this end, acrylic acid and n-butanol were used as starting materials, paratoluene sulfonic acid was used as a catalyst, and phenothiazine was used as a polymerization inhibitor.

As the esterification reactor, a reactor having a volume of 2.5 L and a volume of 5 L was continuously installed and used as a distillation column for a purification step, using a tray column of a 40-stage downcomer type, and a heat flow supply unit provided at the bottom of the distillation column. Reboiler used a thermo siphon type of 400 ml capacity. In addition, the high-boiling addition product decomposition reactor was a reactor in the form of a double jacket (jacket) capacity of 300 ml to maintain the volume of the liquid to 200 ml.

Into the first reactor (R1) of the esterification reactor at a flow rate of 346 g / hr acrylic acid, 359 g / hr n-butanol, respectively, the organic acid catalyst was dissolved continuously in n-butanol 3.0 g / hr paratoluene sulfonic acid The mixed liquid containing n-butanol: butyl acrylate: water as 7: 2: 1 was added to the upper portion of the water separation tower D1, and was further recycled by refining the organic layer recovered to the top of the distillation column in the purification process. Was added at a flow rate of 191 g / hr.

The residence time of the reactants in the first reactor (R1) of the esterification reactor is 1.4 hours, the reaction temperature is 95 ℃, the reaction pressure is 330 Torr, the residence time of the reactants in the second reactor (R2) is 2.9 hours, the reaction temperature is The esterification reaction was carried out such that the reaction pressure was 330 Torr at 103 ° C., and the content of the catalyst in the second reactor (R2) was 1.01 wt%.

Subsequently, the reaction liquid discharged from the second reactor (R2) of the esterification reactor was introduced into the bottom of the distillation column (D2), wherein the upper pressure of the distillation column (D2) was 150 Torr and the upper temperature was 54 ° C. The temperature of the liquid in the heat flow reboiler provided at the bottom of the distillation column was adjusted to 92 ° C.

In addition, a reflux solution containing 96.5% by weight of water and 3.5% by weight of n-butanol was added at a flow rate of 540 g / hr at the top of the distillation column (D2), with butylacrylate containing 1.5% by weight of phenothiazine. It was introduced at a flow rate of g / hr.

On the other hand, the upper discharge liquid of the distillation column (D2) was discharged at a flow rate of 1319 g / hr, the lower discharge liquid 742 g / hr, respectively. At this time, the composition of the top discharge of the distillation column (D2) was butyl acrylate: water: n-butanol ratio of 48.5: 39.5: 12.0, acrylic acid was less than 1 ppm. That is, the amount of water previously supplied from the upper portion of the distillation column D2 (521.1 g / hr) is approximately equal to the amount of water recovered from the upper portion of the distillation column (521.005 g / hr) (about 1.00 times). ).

In addition, the bottom discharge of the distillation column (D2) is less than 1% by weight of water, 2.5% by weight of acrylic acid, 7.4% by weight of n-butanol, 57% by weight of butyl acrylate, the rest of the high boiling point addition product, polymerization inhibitor and catalyst It was a heavy substance such as.

At this time, the bottom discharge liquid of the distillation column (D2) was not separated into the water layer and the organic layer, 148 g / hr which is part of the bottom discharge liquid was introduced into the high boiling point addition product decomposition reactor (R3), the rest of the first ester Recycled to the reactor (R1).

The residence time in the high boiling point addition product decomposition reactor (R3) was 7.5 hours, and the decomposition reaction was performed under conditions of a temperature of 157 ° C. and a pressure of 100 Torr. The top discharge of the cracking reactor (R3) was discharged at a flow rate of 122 g / hr, which was recycled to the first esterification reactor (R1). In addition, the bottom discharge of the heavy material decomposition reactor (R3) was discharged at a flow rate of 26.5 g / hr, of which the content of the organic acid catalyst was 11.5% by weight based on the total weight of the bottom discharge.

When the process was operated for about 70 hours under the above conditions, the solid slurry was deposited in the high boiling point adduct decomposition reactor (R3), and thus, operation was impossible.

Example  One

Butyl acrylate was prepared from the target material of alkyl (meth) acrylate.

To this end, acrylic acid and n-butanol were used as starting materials, methane sulfonic acid was used as a catalyst, and phenothiazine was used as a polymerization inhibitor. In addition, the structure of the used esterification reactor, the distillation column, the heat flow supply part of a distillation column, the high boiling point addition product decomposition reactor, etc. used the same thing as the comparative example 1.

First, 347 g / hr acrylic acid and 360 g / hr n-butanol were introduced into the first reactor (R1) of the esterification reactor, and the organic acid catalyst was dissolved in n-butanol by dissolving 0.7 g / hr of methane sulfonic acid in n-butanol. (At this time, in Example 1, since the amount of catalyst recovered in the step to be described later could be increased and the amount of catalyst discarded was reduced, the amount of catalyst replenished in comparison with Comparative Example 1 in the continuous process was reduced). In the upper portion of the water separation tower D1, a mixed liquid containing n-butanol: butyl acrylate: water as 7: 2: 1 is further recycled by further purifying the organic layer recovered to the top of the distillation column in the purification step. It was introduced at a flow rate of 191 g / hr.

The residence time of the reactants in the first reactor (R1) of the esterification reactor is 1.41 hours, the reaction temperature is 95 ℃, the reaction pressure is 330 Torr, the residence time of the reactants in the second reactor (R2) is 2.9 hours, the reaction temperature is The esterification reaction was performed so that the reaction pressure was 330 Torr at 103 ° C., and the content of the catalyst in the second reactor (R2) was 0.96 wt%.

Subsequently, the reaction liquid discharged from the second reactor (R2) of the esterification reactor was introduced into the bottom of the distillation column (D2), wherein the upper pressure of the distillation column (D2) was 150 Torr and the upper temperature was 54 ° C. The temperature of the liquid in the heat flow reboiler provided at the bottom of the distillation column was adjusted to 83 ° C.

In addition, a reflux liquid of 96.5 wt% water and 3.5 wt% n-butanol was added at a flow rate of 561 g / hr at the top of the distillation column D2.

On the other hand, the upper discharge liquid of the distillation column (D2) was discharged at a flow rate of 1323 g / hr, the lower discharge liquid 761 g / hr. At this time, the composition of the top discharge of the distillation column (D2) was butyl acrylate: water: n-butanol ratio of 48.5: 39.5: 12.0, acrylic acid was less than 1 ppm. That is, the amount of water supplied from the top of the distillation column D2 (converted value 543.365 g / hr) was maintained to be about 1.04 times the amount of water (converted value 522.585 g / hr) recovered from the upper part of the distillation column in the recovery step. .

In addition, the bottom discharge of the distillation column (D2) is 4.8% by weight of water, 2.4% by weight of acrylic acid, 7.2% by weight of n-butanol, 57% by weight of butyl acrylate, and the rest are high boiling point adducts, polymerization inhibitors and catalysts. It was heavy.

At this time, the bottom discharge of the distillation column (D2) was separated into a water layer and an organic layer, 89% by weight of the catalyst used in the esterification reaction was present in the water layer, the water layer is the first esterification reactor (R1) Recycled.

A portion of the organic layer, 150 g / hr, was introduced into the high boiling point adduct decomposition reactor (R3) and the remainder was recycled to the first esterification reactor (R1). In addition, the catalyst concentration in the decomposition reactor (R3) was maintained at 2.8 ~ 3.0% by weight, for this purpose, the water layer separated from the bottom discharge of the distillation column (D2) was intermittently supplied to the decomposition reactor (R3).

The residence time in the high boiling point addition product decomposition reactor (R3) was 8 hours, and the decomposition reaction was performed under conditions of a temperature of 157 ° C. and a pressure of 100 Torr. The top discharge of the cracking reactor (R3) was discharged at a flow rate of 126 g / hr, which was recycled to the first esterification reactor (R1). In addition, the bottom discharge of the decomposition reactor (R3) was discharged at a flow rate of 24 g / hr, wherein the content of the organic acid catalyst was 2.9% by weight relative to the total weight of the bottom discharge.

Even if the process was operated for about 300 hours under the above conditions, the fluidity in the high boiling point addition product decomposition reactor (R3) did not matter.

Example  2

Butyl acrylate was prepared from the target material of alkyl (meth) acrylate.

To this end, acrylic acid and n-butanol were used as starting materials, para toluene sulfonic acid was used as a catalyst, and phenothiazine was used as a polymerization inhibitor. In addition, the structure of the esterification reactor, the distillation column, the heat flow supply part of a distillation column, the high boiling point addition product decomposition reactor, etc. used the same thing as Example 1.

Into the first reactor (R1) of the esterification reactor at a flow rate of acrylic acid 345 g / hr, n-butanol 358 g / hr, respectively, the organic acid catalyst was dissolved by dissolving para toluene sulfonic acid 0.75 g / hr in n-butanol continuously To the top of the water separation column (D1), a mixed solution containing n-butanol: butyl acrylate: water 7: 2: 1 was introduced at a flow rate of 189 g / hr.

The residence time of the reactants in the first reactor (R1) of the esterification reactor is 1.4 hours, the reaction temperature is 95 ℃, the reaction pressure is 330 Torr, the residence time of the reactants in the second reactor (R2) is 2.9 hours, the reaction temperature is The esterification reaction was carried out such that the reaction pressure was 330 Torr at 103 ° C., and the content of the catalyst in the second reactor (R2) was 1.01 wt%.

Subsequently, the reaction liquid discharged from the second reactor (R2) of the esterification reactor was introduced into the bottom of the distillation column (D2), wherein the upper pressure of the distillation column (D2) was 150 Torr and the upper temperature was 54 ° C. The temperature of the liquid in the heat flow reboiler provided at the bottom of the distillation column was adjusted to 76 ° C.

In addition, a reflux solution of 96.5% by weight of water and 3.5% by weight of n-butanol was added at a flow rate of 604 g / hr at the top of the distillation column (D2), with butylacrylate containing 1.5% by weight of phenothiazine. It was introduced at a flow rate of g / hr.

On the other hand, the upper discharge liquid of the distillation column (D2) was discharged at a flow rate of 1315 g / hr, the lower discharge liquid 802 g / hr. At this time, the composition of the top discharge of the distillation column (D2) was butyl acrylate: water: n-butanol ratio of 48.5: 39.5: 12.0, acrylic acid was less than 1 ppm. That is, the amount of water supplied from the top of the distillation column (D2) (equivalent value 582.86 g / hr) was maintained to be about 1.12 times the amount of water (equivalent value 519.425 g / hr) recovered to the top of the distillation column in the recovery step. .

In addition, the bottom discharge of the distillation column (D2) is 10.1% by weight of water, 2.3% by weight of acrylic acid, 6.9% by weight of n-butanol, 54% by weight of butyl acrylate, and the rest are high boiling point addition products, polymerization inhibitors and catalysts. It was heavy.

At this time, the bottom discharge of the distillation column (D2) was separated into a water layer and an organic layer, 78.3% by weight of the catalyst used in the esterification reaction was present in the water layer, the water layer is the first esterification reactor (R1) Recycled.

158 g / hr, part of the organic layer, was introduced into the high boiling point adduct decomposition reactor (R3) and the remainder was recycled to the first esterification reactor (R1). In addition, the catalyst concentration in the decomposition reactor (R3) was maintained at 3.1% by weight, and for this purpose, the water layer separated from the bottom discharge of the distillation column (D2) was intermittently supplied to the decomposition reactor (R3).

The residence time in the high boiling point addition product decomposition reactor (R3) was 8 hours, and the decomposition reaction was performed under conditions of a temperature of 157 ° C. and a pressure of 100 Torr. The top discharge of the cracking reactor (R3) was discharged at a flow rate of 134 g / hr, which was recycled to the first esterification reactor (R1). In addition, the bottom discharge of the decomposition reactor (R3) was discharged at a flow rate of 24 g / hr, wherein the content of the organic acid catalyst was 3.1% by weight relative to the total weight of the bottom discharge.

Even if the process was operated for about 300 hours under the above conditions, the fluidity in the high boiling point addition product decomposition reactor (R3) did not matter.

Example  3

Butyl acrylate was prepared from the target material of alkyl (meth) acrylate.

To this end, acrylic acid and n-butanol were used as starting materials, para toluene sulfonic acid was used as a catalyst, and phenothiazine was used as a polymerization inhibitor. In addition, the structure of the esterification reactor, the distillation column, the heat flow supply part of a distillation column, the high boiling point addition product decomposition reactor, etc. used the same thing as Example 1.

The first reactor (R1) of the esterification reactor was introduced at a flow rate of 348 g / hr acrylic acid and 362 g / hr n-butanol, respectively, and the organic acid catalyst was continuously dissolved by dissolving 0.83 g / hr of para-toluene sulfonic acid in n-butanol. To the top of the water separation column (D1), a mixed solution containing n-butanol: butyl acrylate: water 7: 2: 1 was introduced at a flow rate of 192 g / hr.

The residence time of the reactants in the first reactor (R1) of the esterification reactor is 1.4 hours, the reaction temperature is 95 ℃, the reaction pressure is 330 Torr, the residence time of the reactants in the second reactor (R2) is 2.9 hours, the reaction temperature is The esterification reaction was carried out such that the reaction pressure was 330 Torr at 103 ° C., and the content of the catalyst in the second reactor (R2) was 1.1 wt%.

Subsequently, the reaction liquid discharged from the second reactor (R2) of the esterification reactor was introduced into the bottom of the distillation column (D2), wherein the upper pressure of the distillation column (D2) was 190 Torr and the upper temperature was 58.6 ° C. The temperature of the liquid in the heat flow reboiler provided at the bottom of the distillation column was adjusted to 87 ° C.

In addition, a reflux solution of 96.5% by weight of water and 3.5% by weight of n-butanol was added at a flow rate of 611 g / hr at the top of the distillation column (D2), and butyl acrylate containing 1.5% by weight of phenothiazine was added. It was introduced at a flow rate of g / hr.

On the other hand, the upper discharge liquid of the distillation column (D2) was discharged at a flow rate of 1331 g / hr, the lower discharge liquid 781 g / hr. At this time, the composition of the top discharge of the distillation column (D2) was butyl acrylate: water: n-butanol ratio of 48.5: 39.5: 12.0, acrylic acid was less than 1 ppm. That is, the amount of water supplied from the upper portion of the distillation column D2 (589.615 g / hr) was maintained to be about 1.12 times the amount of water recovered from the upper portion of the distillation column (525.745 g / hr). .

In addition, the bottom discharge of the distillation column (D2) is 6.5% by weight of water, 2.4% by weight of acrylic acid, 7.1% by weight of n-butanol, 55% by weight of butyl acrylate, the remainder of the high boiling point adduct, polymerization inhibitor and catalyst, etc. It was heavy.

At this time, the bottom discharge of the distillation column (D2) was separated into a water layer and an organic layer, 83% by weight of the catalyst used in the esterification reaction was present in the water layer, the water layer is the first esterification reactor (R1) Recycled.

154 g / hr, part of the organic layer, was introduced into the high boiling point adduct decomposition reactor (R3) and the remainder was recycled to the first esterification reactor (R1). In addition, the catalyst concentration in the decomposition reactor (R3) was maintained at 3.4% by weight, and for this purpose, the water layer separated from the bottom discharge of the distillation column (D2) was intermittently supplied to the decomposition reactor (R3).

The residence time in the high boiling point addition product decomposition reactor (R3) was 8 hours, and the decomposition reaction was performed under conditions of a temperature of 157 ° C. and a pressure of 100 Torr. The top discharge of the cracking reactor (R3) was discharged at a flow rate of 129 g / hr, which was recycled to the first esterification reactor (R1). In addition, the bottom discharge of the decomposition reactor (R3) was discharged at a flow rate of 24 g / hr, wherein the content of the organic acid catalyst was 3.4% by weight relative to the total weight of the bottom discharge.

Even if the process was operated for about 300 hours under the above conditions, the fluidity in the high boiling point addition product decomposition reactor (R3) did not matter.

R1 and R2: esterification reactor
R3: high boiling point adduct decomposition reactor
D1: water separation tower
D2: esterification reactant distillation column
B: heat flow reboiler of esterification reactant distillation column
D3: low boiling point material separation tower
D4: Alcohol Recovery Tower
T1, T2, and T4: decanters and receivers
T3: catalyst recovery tank
1 to 3: reactant and catalyst feed lines
4 to 22: reaction product transfer line

Claims (19)

Esterifying the reactant comprising (meth) acrylic acid and alkanol with conversion of at least 70% in the presence of an organic acid catalyst;
Supplying and purifying the reaction product of the esterification reaction to a distillation column having a heat flow reboiler at the bottom;
Recovering an upper effluent including alkyl (meth) acrylate and water in the upper part of the distillation column, and recovering a lower effluent including high boiling point adduct and water in the lower part of the distillation column;
Separating the bottom discharge liquid of the distillation column into a water layer and an organic layer; And
Recycling the water layer separated from the bottom effluent to be used in the esterification reaction, wherein each step occurs continuously,
The water contained in the bottom discharge of the distillation column is 2 to 25% by weight based on the total weight of the discharge liquid alkyl (meth) acrylate manufacturing method.
The method of claim 1,
The method of producing an alkyl (meth) acrylate further comprising the step of supplying 1.01 to 1.20 times the water in the top of the distillation column relative to the weight of the water contained in the discharge liquid discharged to the top of the distillation column.
The method of claim 1,
The pressure of the upper part of the distillation column and the temperature of the liquid in the heat flow supply part are 130 Torr or more and less than 170 Torr and 65 to 90 ° C., respectively;
170 Torr or more and less than 200 Torr and 70 to 95 ° C; or
Process for producing alkyl (meth) acrylates operating at 200 Torr or less and less than 230 Torr and 75 to 100 ° C.
The method of claim 1,
The pressure of the top of the distillation column and the temperature of the liquid in the heat flow supply unit are 130 Torr or more and less than 170 Torr and 65 to 90 ℃, respectively,
170 Torr or more and less than 200 Torr and 70 to 95 ° C, or
Operating at 200 Torr or more and less than 230 Torr and 120 to 140 ° C;
The method of producing an alkyl (meth) acrylate further comprising the step of supplying 1.01 to 1.20 times the water in the top of the distillation column relative to the weight of the water contained in the discharge liquid discharged to the top of the distillation column.
The method of claim 1,
The water layer separated from the bottom discharge of the distillation column is a method for producing an alkyl (meth) acrylate containing at least 50% by weight of the organic acid catalyst supplied to the esterification reaction.
The method of claim 1,
The method of producing an alkyl (meth) acrylate further comprises the step of supplying the organic layer separated from the bottom discharge of the distillation column to the high boiling point addition product decomposition reactor for the decomposition reaction.
The method according to claim 6,
The decomposition reaction proceeds under the conditions of the temperature of 120 to 220 ℃, pressure of 30 to 760 Torr.
The method according to claim 6,
And supplying a portion of the water layer separated from the bottom discharge of the distillation column to the high boiling point adduct decomposition cracking reactor.
The method of claim 8,
The catalyst contained in the high boiling point addition product cracking reactor is 0.01 to 5% by weight relative to the total weight of the reaction liquid supplied to the cracking reactor.
The method according to claim 6,
Recycling the top discharge of the decomposition reactor to the esterification step further comprising the step of producing an alkyl (meth) acrylate.
The method according to claim 6,
Recycling the top effluent of the decomposition reactor to the purification step of the esterification reaction product.
The method according to claim 6,
After the decomposition reaction step, the catalyst contained in the bottom discharge of the decomposition reactor is a method of producing an alkyl (meth) acrylate is 10% by weight or less based on the total weight of the bottom discharge.
The method of claim 1,
Wherein said esterification reaction proceeds in one or more continuous reactors connected in series.
The method of claim 13,
Method for producing an alkyl (meth) acrylate further comprises a water separation column for purifying the water discharged from the top of each of the continuous reactor.
The method of claim 1,
The esterification reaction is carried out under the conditions of temperature 70 to 150 ℃ and pressure 50 to 760 torr alkyl (meth) acrylate production method.
The method of claim 1,
The molar ratio of alkanol to (meth) acrylic acid included in the reactants in the esterification step is 1.05 to 5, wherein the alkyl (meth) acrylate.
The method of claim 1,
The content of the organic acid catalyst in the esterification step is 0.01 to 5% by weight based on the total weight of the reactants.
The method of claim 1,
The alkanol is a method for producing an alkyl (meth) acrylate is an alkanol having 4 to 8 carbon atoms.
The method of claim 1,
The organic acid catalyst is a method for producing an alkyl (meth) acrylate is one or more selected from the group consisting of alkanesulfonic acid and arylsulfonic acid.

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