1,5,9-cyclododecatriene composition and continuous production method thereof

Abstract

The present invention provides a process for continuously producing cyclododecatriene, which comprises mixing butadiene, a main catalyst, and a co-catalyst in a toluene solvent to produce a reaction composition, and reacting the reaction composition at a reaction pressure exceeding the vapor pressure of the butadiene, and a cyclododecatriene composition produced thereby.

Description

[Technical Field]

[0001] The present invention relates to a 1,5,9-cyclododecatriene composition and a continuous process for producing the same. [Background technology]

[0002] 1,5,9-Cyclododecatriene (CDT) is a useful intermediate in the production of organic compounds such as lactams, polyamides, and dicarboxylic acids. 1,5,9-Cyclododecatriene can be synthesized by the cyclotrimerization of 1,3-butadiene. This trimerization reaction is typically carried out by mixing 1,3-butadiene, a catalyst, and other components in a solvent. Examples of solvents used for this reaction include hexane, heptane, octane, decane, cyclohexane, cyclooctane, cyclodecane, cyclododecane, benzene, toluene, and xylene. While benzene has traditionally been used as a solvent, its toxicity to humans and its handling difficulties necessitate the development of alternatives. Toluene, which has similar physical properties to benzene, is just as toxic to humans as benzene, but is relatively easy to handle. However, when toluene is used as a solvent, it has been found that new by-products are generated that are different from the by-products generated when the reaction is carried out in the conventional benzene solvent. Typically, the toluene-C4 complex is formed in excess, resulting in a significant decrease in CDT selectivity.

[0003] Furthermore, this problem did not arise when the reaction was carried out at the conventional laboratory level or in a batch reactor or CSTR reactor, which are types of reactors. However, when mass production is required, such as in the commercial process of CDT, foaming occurs in the reactor, causing a significant decrease in conversion rate.

[0004] Therefore, there is a need for optimized reactor operating conditions to suppress the formation of by-products such as toluene-C4 that are generated when the trimerization reaction is carried out in a toluene solvent, reduce the foaming that occurs in the commercial process for mass-producing CDT, and improve the CDT conversion rate and production volume. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to suppress the production of by-products such as VCH (4-vinylcyclohexane), COD (cyclooctadiene), and toluene-C4 complex in a method for continuously producing CDT.

[0006] In addition, we aim to suppress the foaming phenomenon that occurs during the commercial mass production process of CDT. In addition, the optimized process operating conditions for improving the conversion rate and yield of CDT products can be proposed. [Means for solving the problem]

[0007] One embodiment provides a process for continuously producing cyclododecatriene, comprising mixing butadiene, a main catalyst, and a co-catalyst in a toluene solvent to produce a reaction composition, and reacting the reaction composition at a reaction pressure exceeding the vapor pressure of the butadiene.

[0008] The main catalyst may be one or more of titanium chloride and titanium alkoxide. In the reaction composition, the concentration of the main catalyst may be more than 0.5 mmol / L and less than 2.5 mmol / L.

[0009] The main catalyst and the co-catalyst may be mixed so that the molar ratio of aluminum / titanium (Al / Ti) is 10-100. The butadiene may be mixed in liquid form. The butadiene and toluene solvent may be contained in a weight ratio of 1:1 to 3:1.

[0010] The reaction pressure may be 5 to 10 bar. In the production method, the reaction composition may be reacted at a reaction temperature of 30 to 70°C. In the production method, the reaction composition may be reacted for 30 to 80 minutes.

[0011] Another embodiment provides a cyclododecatriene composition produced by the above production method, wherein the butadiene conversion is 85 wt% or more and the cyclododecatriene selectivity is 85 wt% or more.

[0012] The cyclododecatriene composition may have a VCH (4-vinylcyclohexane) selectivity of less than 1 wt%. The cyclododecatriene composition may have a COD (cyclooctadiene) selectivity of less than 0.2 wt%. The cyclododecatriene composition may have a toluene-C4 (Tol-C4) selectivity of less than 15 wt %. [Effects of the Invention]

[0013] It suppresses the formation of by-products such as toluene-C4, reduces the foaming phenomenon that occurs during the commercial mass production process of CDT, and improves the CDT conversion rate and production volume. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a graph comparing butadiene conversion rates according to main catalyst concentrations in Examples 2 to 6. [Figure 2] 1 is a graph comparing CDT selectivity according to the concentration of the main catalyst in Examples 2 to 6. [Figure 3] 1 is a graph comparing the selectivity of reaction by-products (VCH, COD) according to the concentration of the main catalyst in Examples 2 to 6. [Figure 4]1 is a graph comparing the selectivity of reaction by-products (Tol-C4) according to the concentration of the main catalyst in Examples 2 to 6. DETAILED DESCRIPTION OF THE INVENTION

[0015] The continuous production method for cyclododecatriene (1,5,9-CDT) according to the present invention will be described in detail below. Unless otherwise defined, the technical and scientific terms used herein have the meanings that are commonly understood by those having ordinary skill in the technical field to which the invention pertains. In the following description, descriptions of known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted.

[0016] The present invention addresses the above-mentioned problems of the prior art and proposes a continuous process for producing cyclododecatriene that can achieve high conversion and selectivity in a very economical manner.

[0017] In this specification, unless otherwise specified, butadiene may mean 1,3-butadiene. The toluene solvent may contain toluene in an amount of 90% by volume or more, preferably 95% by volume or more, and more preferably 99% by volume or more, based on the total volume of the solvent.

[0018] Furthermore, in the cyclododecatriene composition, the CDT selectivity, VCH selectivity, COD selectivity, and toluene-C4 selectivity (wt%) may each mean the content (wt%) in the cyclododecatriene composition.

[0019] Furthermore, A to B can mean a range of A or more and B or less. Furthermore, the word "including" in this specification does not exclude other configurations, and should be understood as meaning that other configurations not mentioned may also be included.

[0020] Hereinafter, a method for continuously producing cyclododecatriene (CDT) according to one embodiment is provided, which comprises mixing butadiene, a main catalyst, and a co-catalyst in a toluene solvent to prepare a reaction composition, and reacting the reaction composition at a reaction pressure exceeding the vapor pressure of the butadiene.

[0021] The reaction composition may contain butadiene and toluene in a weight ratio of 1:1 to 3:1, for example, 1:1 to 2:1, preferably 1:1 to 1.5:1. In the present invention, the butadiene and toluene are mixed in the above content ratio in the reaction composition for a commercial process in which the reaction is carried out continuously due to the demand for mass production of CDT. Excessive injection of butadiene caused foaming in the reactor. This foaming is thought to occur due to a rapid increase in temperature in the reactor as the butadiene trimerization reaction proceeds, which leads to a phase change, such as butadiene boiling, which results in contact interruption between the catalyst and butadiene, the formation of a dead zone in the reactor, and an increase in the space velocity of the reaction composition, resulting in a decrease in conversion.

[0022] However, when the process operating conditions of the continuous reactor of the present invention, such as the reaction pressure, reaction temperature, space velocity of the reaction composition, and reactor combination, are applied, butadiene can be added as the reaction composition in an amount greater than the weight of the toluene solvent, thereby suppressing foaming and achieving excellent butadiene conversion, CDT selectivity, and CDT production. For example, if the weight ratio of butadiene to toluene is less than 1:1, CDT production is insufficient, and if the weight ratio exceeds 3:1, butadiene conversion decreases, and it is difficult to optimize the reactor operating conditions, resulting in problems such as increased operating costs due to sludge generation.

[0023] As previously mentioned, toluene as a solvent for trimerization has the advantages of being easy to handle, less harmful to humans, and readily available, while possessing similar physical properties to conventionally used benzene. However, while by-products reportedly generated when using benzene solvent include 4-vinylcyclohexane (VCH), cyclooctadiene (COD), polymers, and 1-phenyl butene (PhB), the use of the toluene solvent of the present invention poses the problem of excessive production of toluene-C4 (toluene-C4) complexes in addition to VCH (4-vinylcyclohexane) and COD (cyclooctadiene), resulting in a significant decrease in CDT selectivity. However, the formation of toluene-C4 complexes can be suppressed by applying the process operating conditions of the CSTR reactor of the present invention, such as the reaction pressure, reaction temperature, space velocity of the reaction composition, and reactor combination.

[0024] The main catalyst may include one or more of titanium chloride and titanium alkoxide, and the co-catalyst may include one or more of organoaluminum, such as ethoxydiethylaluminum, diethylaluminum chloride, and ethylaluminum sesquichloride (EASC). Preferably, titanium tetrachloride (TiCl4) or titanium alkoxide may be used as the main catalyst, and ethoxydiethylaluminum or EASC may be used as the co-catalyst, but is not limited thereto.

[0025] The main catalyst may be contained in an amount of 0.001 to 0.1 wt%, for example, 0.01 to 0.1 wt%, preferably 0.01 to 0.07 wt%, more preferably 0.01 to 0.05 wt%, or 0.01 to 0.04 wt%, based on the total weight of the reaction composition. The concentration of the main catalyst in the reaction composition may be more than 0.5 mmol / L and less than 2.5 mmol / L, preferably 0.6 to 2 mmol / L, or 0.6 to 1.5 mmol / L, more preferably 0.6 to 1.3 mmol / L, or 0.7 to 1.1 mmol / L, and most preferably 0.6 to 1 mmol / L, or 0.7 to 0.9 mmol / L.

[0026] If the content of the main catalyst is too low, it is difficult to provide sufficient active sites, and the butadiene trimerization reaction may not proceed satisfactorily. If the content of the main catalyst is too high, the temperature of the reactor may rise rapidly, accelerating the formation of reaction by-products and causing sludge accumulation in the reactor.

[0027] The co-catalyst may be contained in an amount of 0.01 to 5% by weight, for example, 0.1 to 5% by weight, preferably 0.5 to 5% by weight, and more preferably 1 to 3% by weight, relative to the total weight of the reaction composition, but the present invention is not limited thereto.

[0028] The main catalyst and co-catalyst may be included in the reaction composition such that the aluminum / titanium molar ratio (Al / Ti molar ratio) is 10 to 100, preferably 20 to 80, or 30 to 70, and more preferably 35 to 65, or 40 to 60. It is generally known that when the aluminum / titanium molar ratio of the co-catalyst to the main catalyst is 15 to 20 or more, the CDT selectivity and butadiene conversion rate decrease (see Korean Chem. Eng. Res., 51(3), 394-402 (2013), Synthesis of Cyclododecatriene from 1,3-Butadiene by Trimerization over Amine-Titanium Complex Catalyst, Table 2). However, under the reaction conditions of the present invention, even better CDT selectivity and butadiene conversion rate can be obtained within the above ranges, which reduces the amount of main catalyst used and simplifies the main catalyst regeneration process, thereby improving process efficiency.

[0029] The reaction is characterized by being carried out at a reaction pressure exceeding the vapor pressure of the butadiene. Therefore, the butadiene may be injected in liquid form, or may be injected at an equal weight or an excess weight relative to the toluene solvent. For example, if the reaction pressure is lower than the vapor pressure of butadiene, foaming may occur in the reactor, reducing the butadiene conversion and CDT selectivity. If the reaction pressure is too high, CDT selectivity may also decrease.

[0030] Specifically, the butadiene trimerization polymerization reaction may be carried out at a reaction temperature of 30 to 70°C, preferably 40 to 60°C, more preferably 45 to 55°C, and at a reaction pressure of 5 to 10 bar, preferably 5 to 9 bar, more preferably 5 to 7 bar, or 5 to 6 bar.

[0031] The trimerization reaction is carried out by increasing the reactor temperature from an initial temperature of 25°C (room temperature) to about 30-50°C and maintaining the temperature within the above reaction temperature range. If the reaction temperature is too low, the catalytic activity is poor, resulting in a low butadiene conversion rate. If the reaction temperature is too high, foaming may occur, reducing the butadiene conversion rate and increasing the VCH selectivity among the by-products.

[0032] The butadiene trimerization polymerization reaction may be carried out for 30 to 80 minutes, preferably 40 to 70 minutes, under the above reaction temperature and reaction pressure conditions, but the present invention is not limited thereto.

[0033] Meanwhile, the butadiene trimerization polymerization reaction may be carried out in at least one selected from a continuous stirred tank reactor (CSTR) and a plug flow reactor (PFR), thereby producing CDT continuously.

[0034] A CSTR is a type of continuous reactor that allows the reaction components to be continuously added and provides a stirring effect during the reaction, thereby maintaining a uniform temperature during the reaction and reducing the likelihood of localized hot spots. However, it has the disadvantages of a low conversion rate of the reaction components per reactor volume and a broad molecular weight distribution of the reaction product due to residual polymers that are not discharged within the residence time.

[0035] In addition, PFR, which is one of the other continuous reactors, is relatively easy to maintain because it does not require stirring and has a high conversion rate per reactor volume, but it has the disadvantages of being difficult to control the temperature inside the reactor and having a high probability of localized hot spots occurring when the reaction is exothermic.

[0036] However, according to one embodiment of the present invention, while maintaining high CDT productivity, it is possible to suppress the generation of by-products such as a broad molecular weight distribution, thereby achieving high CDT selectivity and butadiene conversion, thereby enabling highly efficient and optimized continuous CDT production.

[0037] Another embodiment of the present invention provides a cyclododecatriene composition produced by the above-mentioned continuous production method of cyclododecatriene and having the following physical properties:

[0038] The cyclododecatriene composition may have a butadiene (BD) conversion rate of 85 wt% or more, 87 wt% or more, 90 wt% or more, or 95 wt% or more.

[0039] The cyclododecatriene composition may have a cyclododecatriene (CDT) selectivity (content) of 85 wt% or more, 87 wt% or more, 90 wt% or more, 91 wt% or more, 92 wt% or more, 95 wt% or more, or 97 wt% or more.

[0040] The cyclododecatriene composition may have a VCH (4-vinylcyclohexane) selectivity (content) of less than 1 wt%, less than 0.8 wt%, less than 0.5 wt%, or less than 0.3 wt%.

[0041] The cyclododecatriene composition may have a COD (cyclooctadiene) selectivity (content) of less than 0.2 wt%, less than 0.19 wt%, less than 0.18 wt%, less than 0.17 wt%, less than 0.15 wt%, less than 0.14 wt%, or less than 0.13 wt%.

[0042] The cyclododecatriene composition may have a toluene-C4 (Tol-C4) selectivity (content) of less than 15 wt%, less than 13 wt%, less than 11 wt%, less than 9 wt%, less than 7 wt%, less than 5 wt%, less than 3 wt%, or less than 1 wt%.

[0043] Therefore, it is possible to suppress the formation of by-products such as toluene-C4, reduce the foaming phenomenon that occurs in the commercial process of mass-producing CDT, and improve the CDT conversion rate and production volume.

[0044] An example according to an embodiment will be described below. However, the following example is provided to explain in detail an example of the present invention and to facilitate a better understanding of the present invention, and it is clear that the scope of the present invention is not limited thereto.

[0045] Example Example 1 At least three batches of CSTR reactions were conducted in a 0.6 L reactor, each containing 200 g of toluene, 200 g of 1,3-butadiene, 1 mmol / L of TiCl4, and a 56 molar ratio of EASC (Al / Ti = 56). The CSTR operating conditions were 50°C and 5 bar, with a residence time of 20 min per batch and a fixed agitation speed of 500 rpm. The selectivity and butadiene conversion of the reaction products were calculated by GC (gas chromatography). The presence or absence of sludge inside the CSTR was visually confirmed, and the results are shown in Table 1 below.

[0046] Evaluation example Evaluation example 1: Evaluation of butadiene conversion rate and sludge generation due to changes in CSTR reaction pressure (Comparative Example 1) The same procedure as in Example 1 was carried out, except that the CSTR operating conditions were 50°C and 1.5 bar.

[0047] [Table 1]

[0048] (Evaluation of sludge generation: ◎: sludge present, ○: small amount of sludge present, X: no sludge present)

[0049] 1,3-butadiene injected in liquid form has a boiling point of -4.4°C and a vapor pressure of 2.5 bar at 20°C and 5.7 bar at 50°C, which are the reaction conditions. Referring to Table 1, it was confirmed that CDT yield and selectivity were ensured when the reaction was carried out at a reaction pressure exceeding the vapor pressure. This result was analyzed to be due to the suppression of vaporization and foaming of 1,3-butadiene.

[0050] Furthermore, toluene, which was used as a solvent, has similar physical properties to benzene but is easy to handle, less harmful to humans than conventional benzene solvents, and is readily available. However, in Comparative Example 1, an excess of toluene-C4 complex was generated as a reaction by-product, significantly reducing CDT selectivity. In contrast, in Example 1, the CDT production reaction was carried out at a reaction pressure exceeding the vapor pressure of butadiene, thereby suppressing the production of toluene-C4.

[0051] Evaluation example 2: Evaluation of butadiene conversion and reaction product selectivity depending on the concentration of the main catalyst Examples 2 to 5 The same procedures as in Example 1 were carried out, except that the concentrations of the main catalyst and the co-catalyst were as shown in Table 2 below. The selectivity and butadiene conversion of the reaction products of Examples 2 to 6 were calculated by GC (gas chromatography) analysis, and the results are shown in Figures 1 to 4.

[0052] [Table 2]

[0053] Figure 1 is a graph comparing butadiene conversion rates according to the main catalyst concentration. Referring to Figure 1, in Examples 3 and 4, the butadiene conversion rate increased to 90% or more, whereas in Example 2 the butadiene conversion rate was less than 90%, and in Examples 5 and 6 the butadiene conversion rate deteriorated to less than 85%. This confirms that the preferred range of the main catalyst concentration is 0.75 to 1 mmol / L. This result is analyzed to be due to the fact that when the main catalyst concentration is less than 0.75 mmol / L, sufficient active sites are not provided, making it difficult for the butadiene trimerization reaction to proceed, and when the concentration exceeds 1 mmol / L, the temperature in the reactor rises sharply.

[0054] Figure 2 is a graph comparing CDT selectivity by main catalyst concentration. Referring to Figure 2, it was confirmed that Examples 3 to 6 had high CDT selectivity of 90% or more, and the preferred range of main catalyst concentration was 0.75 mmol / L.

[0055] 3 and 4 are graphs comparing the selectivity to reaction by-products (VCH, COD, Tol-C4) depending on the concentration of the main catalyst. Referring to FIG. 3, it was analyzed that VCH increases in proportion to the catalyst concentration, while COD remains almost unchanged over the entire concentration range. Referring to FIG. 4, Tol-C4 showed a tendency to be inversely proportional to the catalyst concentration, and it was analyzed that there was no significant difference in the production amount between 0.75 and 1 mmol / L.

[0056] From the results in Table 2 and Figures 1 to 4, it can be seen that the concentration of the main catalyst for optimal reactivity of the butadiene trimerization reaction is more than 0.5 mmol / L and less than 1 mmol / L, preferably 0.75 mmol / L.

[0057] Evaluation Example 3: Evaluation of butadiene conversion and reaction product selectivity for each promoter concentration (Al / Ti molar ratio) Examples 7 to 9 The butadiene trimerization reaction was carried out for 60 minutes at the optimum concentration of the main catalyst of 0.75 mmol / L and at different concentrations of the cocatalyst EASC (Al / Ti mole ratio). The results are shown in Table 3 below.

[0058] [Table 3]

[0059] From the results in Table 3, it was found that the concentration of the co-catalyst for the optimum reactivity of the butadiene trimerization reaction is an Al / Ti ratio of 30 to 70 moles, preferably 40 to 60 moles.

[0060] Although the present invention has been described above using specific details and limited examples, these are merely provided for a more comprehensive understanding of the present invention, and the present invention is not limited to the above examples. Those skilled in the art will appreciate that various modifications and variations can be made from these descriptions. Therefore, the scope of the present invention should not be limited to the described examples, and all equivalent or similar modifications to the claims, as well as the following claims, are considered to fall within the scope of the present invention.

Claims

1. mixing butadiene, a main catalyst, and a cocatalyst in a toluene solvent to produce a reaction composition; reacting the reaction composition at a reaction temperature of 40 to 60°C and a reaction pressure of 5 to 10 bar; the reaction composition is free of Lewis bases; The butadiene and the toluene solvent are contained in a weight ratio of 1:1 to 3:1, The main catalyst contains at least one of titanium chloride and titanium alkoxide, The co-catalyst comprises at least one organoaluminum selected from the group consisting of ethoxydiethylaluminum, diethylaluminum chloride, and ethylaluminum sesquichloride (EASC).

2. 2. The continuous process for producing cyclododecatriene according to claim 1, wherein the concentration of the main catalyst in the reaction composition is more than 0.5 and less than 2.5 mmol / L.

3. 2. The method for continuously producing cyclododecatriene according to claim 1, wherein the main catalyst and the co-catalyst are mixed so that the aluminum / titanium molar ratio (Al / Ti molar ratio) is 10 to 100.

4. 2. The continuous process for producing cyclododecatriene according to claim 1, wherein the butadiene is mixed in a liquid state.

5. 2. The continuous process for producing cyclododecatriene according to claim 1, wherein the reaction composition is reacted for 30 to 80 minutes.

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