KR20200064619A - A Method for Manufacturing Dialkyl Terephthalate-based Composition - Google Patents

Abstract

The present invention relates to a method for manufacturing a dialkyl terephthalate-based composition. The manufacturing method of the present invention can reduce additional energy consumption required for heating alcohol by keeping the temperature of a primary alcohol to be re-input relatively high, thereby being economical.

Description

A method for manufacturing dialkyl terephthalate-based composition

The present invention relates to a method for preparing a dialkyl terephthalate-based composition, specifically, energy consumed for additional heating by controlling the temperature of primary alcohol that is refluxed and fed back into the reactor and unreacted alcohol that has not been used in the previous process. It relates to a method for producing an economical dialkyl terephthalate-based composition by reducing the.

Phthalate plasticizers account for 92% of the global plasticizer market (Mustafizur Rahman and Christopher S.Brazel "The plasticizer market: an assessment of traditional plasticizers and research trends to meet new challenges" Progress in Polymer Science 2004, 29, 1223-1248 Note), mainly used to improve the processability by giving flexibility, durability, cold resistance, etc. to polyvinyl chloride (hereinafter referred to as PVC) and lowering the viscosity during melting. From hard products to soft, yet stretchable, soft products that can be used for food packaging, blood bags, flooring, etc., it has a close connection with real life than any other material and is widely used for direct contact with the human body.

However, despite its compatibility with PVC and phthalate-based plasticizers, and excellent softness, recently, PVC products containing phthalate-based plasticizers leaked little by little to the outside of the product, resulting in endocrine system disorders (environmental hormone) and heavy metal levels. Controversy has been raised about the potential to act as a carcinogen (NR Janjua et al. "Systemic Uptake of Diethyl Phthalate, Dibutyl Phthalate, and Butyl Paraben Following Whole-body Topical Application and Reproductive and Thyroid Hormone Levels in Humans" Environmental Science and Technology 2008, 42, 7522-7527). In particular, the environmental hormone was introduced in the 1990s after reports of di-(2-ethylhexyl) phthalate (DEHP), which is the most used phthalate plasticizer in the United States, leaked outside PVC products in the 1960s. With increasing interest in phthalate-based plasticizers, global environmental regulations have started to be implemented, including various studies on human health hazards.

In response, many researchers have developed a new non-phthalate-based alternative plasticizer that eliminates phthalic anhydride used in the production of phthalate-based plasticizers or suppresses the outflow of phthalate-based plasticizers to counter environmental hormone problems and environmental regulations caused by phthalate-based plasticizer spills. Research is underway to develop a spill control technology that can significantly reduce risks and meet environmental standards.

On the other hand, as a non-phthalate-based plasticizer, terephthalate-based plasticizers are not only at the same level in terms of physical properties as phthalate-based plasticizers, but are also in the spotlight as materials free from environmental problems, and various types of terephthalate-based plasticizers are being developed. In addition, research on developing terephthalate-based plasticizers having excellent physical properties as well as research on facilities for manufacturing such terephthalate-based plasticizers has been actively conducted, and more efficient, economical and simple process design in terms of process design Is required.

Representative terephthalate plasticizers include dibutyl terephthalate, dibutyl terephthalate is prepared by transesterification of dioctyl terephthalate and butyl alcohol, and the dioctyl terephthalate is prepared by esterifying terephthalic acid and octanol. It is common to do. However, there is a problem that water, a product produced in the manufacturing process of the dioctyl terephthalate, and octanol, a reactant, are easily evaporated at a temperature at which the esterification reaction is performed. Was used, and refluxed octanol was introduced into the reactor again, and at the beginning of the process, the unreacted octanol remaining from the previous process was also used. On the other hand, in this conventional technique, the octanol evaporated during the reaction and the unreacted octanol, which was not used in the previous process, had to be condensed to input the octanol back into the reactor. Since the esterification reaction can be performed only when the silver is heated again, there is a problem in that energy is consumed.

Mustafizur Rahman and Christopher S. Brazel "The plasticizer market: an assessment of traditional plasticizers and research trends to meet new challenges" Progress in Polymer Science 2004, 29, 1223-1248 N. R. Janjua et al. "Systemic Uptake of Diethyl Phthalate, Dibutyl Phthalate, and Butyl Paraben Following Whole-body Topical Application and Reproductive and Thyroid Hormone Levels in Humans" Environmental Science and Technology 2008, 42, 7522-7527

The present invention is to solve the problems of the prior art as described above, by reducing the supercooling of unreacted alcohol and reflux alcohol to be re-introduced, to provide an energy-efficient method for producing a dialkyl terephthalate-based composition.

In order to solve the above problems, the present invention is a step of generating dialkyl terephthalate and water having 7 to 10 carbon atoms of an alkyl group by introducing terephthalic acid and a primary alcohol having 7 to 10 carbon atoms into a reactor and performing an esterification reaction (S1). ); In the alcohol and water vaporized during the reaction, the step of selectively separating the alcohol through condensation and layer separation to re-enter the reactor (S2); Extracting water and unreacted primary alcohol after the reaction is completed (S3); And, among the extracted water and unreacted primary alcohol, selectively unreacted primary alcohol through condensation and layer separation to re-enter the reactor (S4); Including, wherein the step S2 is performed intermittently or continuously while the step S1 is performed, and the temperature of the alcohol re-introduced into the reactor in the step S2 or S4 is controlled to be 60 to 95° C. The dialkyl terephthalate system Provides a method for preparing the composition.

In the manufacturing method of the present invention, since alcohol having a relatively higher temperature is refluxed and reused than the conventional manufacturing method, it is economical because less energy is consumed to increase the temperature for the reaction.

1 is a simplified diagram of a manufacturing method of an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail.

The terms or words used in the specification and claims should not be interpreted as being limited to ordinary or lexical meanings, and the inventor can appropriately define the concept of terms in order to explain his or her invention in the best way. Based on the principle that it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.

The present invention is a step of generating a dialkyl terephthalate and water having 7 to 10 carbon atoms of an alkyl group by introducing terephthalic acid and a primary alcohol having 7 to 10 carbon atoms into a reactor and performing an esterification reaction (S1);

In the alcohol and water vaporized during the reaction, the step of selectively separating the alcohol through condensation and layer separation to re-enter the reactor (S2);

Extracting water and unreacted primary alcohol after the reaction is completed (S3); And

A step of selectively separating unreacted primary alcohol through condensation and layer separation from the extracted water and unreacted primary alcohol and re-injecting it into the reactor (S4); It includes,

The step S2 is performed intermittently or continuously while the step S1 is performed,

Provided is a method for preparing a dialkyl terephthalate-based composition in which the temperature of the alcohol re-entered into the reactor in the step S2 or S4 is controlled to 60 to 95°C.

Hereinafter, the manufacturing method of the present invention will be described in detail step by step.

The manufacturing method of the present invention includes the step (S1) of introducing dialkyl terephthalate and water having 7 to 10 carbon atoms of the alkyl group by introducing terephthalic acid and primary alcohol having 7 to 10 carbon atoms into the reactor and performing an esterification reaction. .

The step S1 is a step in which a reactant terephthalic acid and a primary alcohol having 7 to 10 carbon atoms are introduced into a reactor and reacted to obtain a dialkyl terephthalate compound having 7 to 10 carbon atoms of the product alkyl group.

The esterification reaction of step S1 may be performed as shown in Scheme 1 below:

[Scheme 1]

.

.

In Reaction Scheme 1, R ₁ may be a monovalent hydrocarbon group having 7 to 10 carbon atoms. The esterification reaction may be carried out under an acid catalyst or a metal catalyst, and when the catalyst is used, the reaction time may be shortened.

Sulfuric acid, methanesulfonic acid or p-toluenesulfonic acid may be used as the acid catalyst, and an organometallic catalyst, metal oxide catalyst, metal salt catalyst or metal itself may be used as the metal catalyst, and the metal component of the metal catalyst As tin, titanium, zirconium, etc. may be used, and it is preferable to use titanium.

The catalyst may be a catalyst that requires a catalyst neutralization step afterwards, and the catalyst neutralization step may be performed after all the production methods of the present invention are performed. The catalyst neutralization may be performed using an aqueous soda ash or caustic soda solution, and preferably may be performed using soda ash.

As a product of the esterification reaction, dialkyl terephthalate having 7 to 10 carbon atoms is produced, and water is produced as a by-product. The water is evaporated during the reaction and then discharged in step S2.

The esterification reaction may be performed at a temperature of 185 to 220°C, preferably at a temperature of 185 to 215°C, more preferably at a temperature of 185 to 210°C. Therefore, the step S1 may include a temperature increase step of raising the temperature of the reactor after the deposit.

When the esterification reaction is performed at such a high temperature, formation of H ⁺ ions necessary for the reaction may be easy, and water generated as a result of the reaction evaporates, and the chemical equilibrium of the esterification reaction moves in the positive reaction direction to finalize the product. There is an advantage that the yield can be high. When the temperature of the reactor is lower than 185°C, the technical advantages of the above-described high temperature reaction may not be sufficiently exhibited, and when the temperature is higher than 220°C, not only water, but also primary alcohols having 7 to 10 carbon atoms as reactants are excessively large. As it evaporates, the concentration of reactants may drop and reaction progress may be difficult.

The reactor used for the reaction may be a batch reactor.

Reflux stage (S2 stage)

The manufacturing method of the present invention includes the step (S2) of re-injection into the reactor by selectively separating the alcohol through condensation and layer separation in alcohol and water vaporized during the reaction.

In step S2, after condensing the mixed gas of water and alcohol, the layers are separated and only alcohol can be re-introduced into the reactor. The step S2 may be performed intermittently or continuously while the step S1 is performed.

As described in step S1, in the process of preparing a dialkyl terephthalate-based composition, which is generally performed at a high temperature of 185° C. or higher, there is a problem of evaporating not only water as a by-product, but also alcohol as a reactant, compared to terephthalic acid. The process economy was secured by using excess alcohol, condensing the evaporated water and alcohol, and then separating only the alcohol and refluxing it back to the reactor.

However, since the above method also condenses and separates and the alcohol that is re-entered into the reactor is supercooled in the condensation step, there is another problem that additional energy is consumed in order to increase the temperature of the alcohol again. The loss of unnecessary energy increases more as the size of the entire process increases, and the amount of alcohol to be heated again increases, so it is a part that must be minimized for economic efficiency of the process.

Accordingly, the inventors of the present invention control the temperature of the alcohol that is condensed and separated and re-entered into the reactor in advance to a suitable range, and then input to the reactor to dialkyl terephthalate-based composition capable of minimizing the energy consumed to further heat the alcohol I would like to propose a manufacturing method of.

Specifically, in the method for preparing the dialkyl terephthalate-based composition of the present invention, the temperature of the alcohol re-introduced into the reactor in step S2 may be controlled to 60 to 95°C, and more specifically, to 70 to 95°C. It can be. If the temperature is lower than this, the amount of energy used to heat the alcohol again is too small, and thus there is no technical advantage of the present invention, and when it is higher, the condensation of the alcohol is not properly performed, and the separation of the layer of water and alcohol after condensation Since it is not clear, there is a problem that it is difficult to separate water from alcohol and to re-enter alcohol.

The temperature control of the alcohol may be performed during condensation. For example, when condensing gaseous alcohol, the temperature of the condensed alcohol can be controlled by controlling the flow rate of the cooling water used in the condenser. The flow rate may be appropriately selected within a range for achieving the object of the present invention according to the temperature value desired by a person skilled in the art, the temperature of the cooling water used, or the heat exchanger design of the condenser.

The separation is performed by the density difference between condensed alcohol and water. The density of alcohol having 7 to 10 carbon atoms is lower than that of water, and the alcohol is located in the upper layer and the lower layer, and the separated layer is discharged or re-entered into the reactor. For example, since the density of octanol is about 780 to 810kg/m ³ in the temperature range, and the density of water is 960 to 990kgm/m ³ , octanol with low density is refluxed in the upper portion and re-entered into the reactor, and water with high density Is discharged from the lower layer.

Reuse of unreacted primary alcohol (S3 and S4)

Even if the esterification reaction to produce dialkyl terephthalate and water is terminated, for chemical equilibrium, some of the reactant primary alcohols must remain unreacted. Therefore, when the remaining unreacted primary alcohol is collected and used as a reactant again in the next process, the cost consumed in the entire process can be reduced.

The unreacted primary alcohol and water are present in the state of a mixed gas because the remaining unreacted primary alcohol is present in the gas state in the reactor after the reaction is over, and the product water is also present in the gas state in the reactor. Therefore, in order to use the unreacted primary alcohol again in the next step, it is necessary to selectively separate the unreacted primary alcohol mixture from the mixture. The separation may be performed through condensation and layer separation as previously performed in step S2.

As in the step S2, since the unreacted primary alcohol re-introduced in the step S4 must also be heated to the above-mentioned temperature range for the esterification reaction, additional heating is performed when the temperature of the unreacted primary alcohol is also controlled in advance. In order to reduce the energy consumed.

Therefore, the temperature of the unreacted primary alcohol re-introduced in the step S4 of the manufacturing method of the present invention may be controlled to 60 to 95°C, and specifically, may be controlled to 70 to 95°C. When the temperature of the re-injected unreacted primary alcohol is outside the above temperature range, the problems described in the step S2 may be the same.

The temperature control may be performed in step S2 or S4, and preferably performed in step S4. When the temperature control is performed in step S4, more energy can be saved than in the step S2.

The temperature of the primary alcohol re-introduced into the reactor in the step S2 or S4 can be controlled through various methods. Specifically, it can be controlled by adjusting the flow rate of the cooling water during condensation. The flow rate may be appropriately selected within a range for achieving the object of the present invention according to the temperature value desired by a person skilled in the art, the temperature of the cooling water used, or the heat exchanger design of the condenser.

The primary alcohol having 7 to 10 carbon atoms as a reactant of the present invention is 1-heptanol, 2-methylhexyl alcohol, 3-methylhexyl alcohol, 2-ethylpentyl alcohol, 3-ethylpentyl alcohol, 1-octanol, 2 -Methylheptyl alcohol, 3-methylheptyl alcohol, 2-ethylhexyl alcohol, and the like, and preferably 2-ethylhexyl alcohol.

The reactor used in the production method of the present invention may be a batch reactor.

Example

Hereinafter, preferred embodiments are provided to help understanding of the present invention. The following examples are only intended to illustrate the invention and are not intended to limit the scope of the invention.

In the embodiment of the present invention, the temperature of the alcohol re-introduced into the reactor in the steps S2 and S4 is controlled through simulation, and thus, it is confirmed how the total amount of heat consumed in heating the reactor changes. Simulation was performed on a process of preparing a dialkyl terephthalate-based composition containing dioctyl terephthalate (DOTP) using 2-ethylhexyl alcohol as an alcohol having 7 to 10 carbon atoms. As a reactor, a batch reactor was selected, and Aspen Batch Modeler from AspenTech was used for the simulation program. The process of this example is simplified and shown in FIG. 1.

The temperature of the re-used alcohol and the alcohol to be re-entered into the reactor was different, and a total of 11 examples and 1 comparative example were carried out, and the re-used alcohol of each example and the comparative example and the alcohol to be re-entered into the reactor separately The temperature is summarized in Table 1 below.

S4 step re-injection alcohol temperature (℃) S2 step re-injection alcohol temperature (℃) Example 1 95 95 Example 2 95 50 Example 3 90 50 Example 4 80 50 Example 5 70 50 Example 6 60 50 Example 7 50 95 Example 8 50 90 Example 9 50 80 Example 10 50 70 Example 11 50 60 Comparative Example 1 50 50

Experimental Example-Checking calories consumed

For Examples 1 to 11 and Comparative Example 1, the total amount of heat consumed per ton of the reactant terephthalic acid (TPA) was calculated, and indexed. The indexing was performed by normalizing 10130 to the minimum value. The results are summarized in Table 2 below.

Annual total heat consumed per tonne of reactant TPA (GJ) Calorie index Example 1 10151 18.7 Example 2 10154 20.9 Example 3 10163 28.6 Example 4 10178 41.8 Example 5 10194 56.0 Example 6 10210 70.3 Example 7 10223 81.3 Example 8 10224 82.4 Example 9 10224 82.4 Example 10 10224 82.4 Example 11 10225 83.5 Comparative Example 1 10244 100

From Table 2, it was confirmed that when preparing the dialkyl terephthalate-based composition through the manufacturing method of the present invention, a large amount of annual energy can be saved. When comparing the annual consumed energy of Example 1 in which the least energy was consumed and Comparative Example 1 in which the most energy was consumed, it was possible to reduce energy equivalent to 93 GJ per year based on the TPA 1-ton process, and in general, 0.5 Gcal. Considering that 1 ton of steam is required to perform heating, it has been confirmed that about 44.5 tons of steam can be saved per year. Since this is based on a 1 ton process, it was confirmed that when applied to a process for producing a large amount of dialkyl terephthalate-based composition, a significant amount of energy can be saved annually through the manufacturing method of the present invention.

Claims (6)

Introducing terephthalic acid and a primary alcohol having 7 to 10 carbon atoms into the reactor and esterifying to generate dialkyl terephthalate and water having 7 to 10 carbon atoms in the alkyl group (S1);
In the alcohol and water vaporized during the reaction, the step of selectively separating the alcohol through condensation and layer separation to re-enter the reactor (S2);
Extracting water and unreacted primary alcohol after the reaction is completed (S3); And
A step of selectively separating unreacted primary alcohol through condensation and layer separation from the extracted water and unreacted primary alcohol and re-injecting it into the reactor (S4); It includes,
The step S2 is performed intermittently or continuously while the step S1 is performed,
The method of preparing a dialkyl terephthalate-based composition wherein the temperature of the alcohol re-introduced into the reactor in step S2 or S4 is controlled to 60 to 95°C.
According to claim 1,
The method of preparing a dialkyl terephthalate-based composition wherein the temperature of the alcohol re-introduced into the reactor is controlled at 70 to 95°C.
According to claim 1,
The method of preparing a dialkyl terephthalate-based composition wherein the temperature of the alcohol re-introduced into the reactor in step S4 is controlled to 60 to 95°C.
According to claim 1,
The temperature of the alcohol to be re-entered into the reactor is controlled by controlling the flow rate of cooling water during the condensation.
According to claim 1,
The method for producing a dialkyl terephthalate-based composition wherein the primary alcohol having 7 to 10 carbon atoms is 2-ethylhexyl alcohol.
According to claim 1,
The reactor is a batch reactor, a method for producing a dialkyl terephthalate-based composition.

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