Preparation system of phthalonitrile-based compounds and preparation method of phthalonitrile-based compounds using the same

Abstract

The invention discloses a system for preparing a phthalonitrile compound and a method for preparing a phthalonitrile compound using the system. The system for preparing a phthalonitrile compound is a system for preparing a phthalonitrile compound using a continuous process, and comprises: a first reaction section filled with a mixture containing a phthalic acid compound and a nitrile compound; a second reaction section connected to the first reaction section; and a discharge section connected to the second reaction section, wherein a fluid flows from the first reaction section to the discharge section in the second reaction section, and a length of the second reaction section in the fluid flow direction is more than 10 times the square root of an average cross-sectional area perpendicular to the fluid flow direction.

Description

Technical Field

[0001] The invention relates to a system for preparing a phthalonitrile compound and a method for preparing the phthalonitrile compound using the system. Background Art

[0002] Phthalonitrile compounds are important compounds used as intermediates in the preparation of linear fiber-forming polymers. Phthalonitrile compounds are also used as organic synthesis intermediates for various fine chemical products such as amines, amides and complex nitrogen dyes. They are also used as high value-added raw materials for plasticizers, alkyd resin modifiers, pesticides, etc.

[0003] In the past, phthalonitrile compounds were prepared by contacting xylene compounds with ammonia and oxygen-containing gas in the presence of an oxidation catalyst and performing a dehydration reaction. However, the above method uses ammonia gas as a harmful chemical substance, and is an ammoxidation (ammoxidation) reaction carried out in the presence of a catalyst under high temperature and high pressure, so the process is complicated, and it is also necessary to separate high-boiling impurities by distillation purification, so there is a problem of being difficult to remove by-products. In addition, in this existing preparation method of phthalonitrile compounds, the yield of the product changes according to the type of catalyst used in the ammoxidation reaction and the oxygen-containing gas ratio, and the conversion rate of the xylene compounds as precursor substances changes according to the reaction temperature, so it is difficult to control the process.

[0004] Therefore, there is an increasing demand for processes for preparing high-purity phthalonitrile-based compounds in an economical and environmentally friendly manner. Summary of the invention

[0005] Technical issues

[0006] The present invention aims to provide a method for directly preparing phthalonitrile compounds from phthalic acid compounds in an environmentally friendly manner and a preparation system suitable therefor.

[0007] Technical Solution

[0008] According to one aspect, a system for preparing phthalonitrile compounds is provided, which is a system for preparing phthalonitrile compounds using a continuous process, and the system for preparing phthalonitrile compounds comprises: a first reaction section filled with a mixture containing phthalic acid compounds and nitrile compounds; a second reaction section connected to the first reaction section; and a discharge section connected to the second reaction section; in the second reaction section, there is a fluid flow from the direction of the first reaction section to the direction of the discharge section, and the length of the second reaction section in the fluid flow direction is more than 10 times the square root of the average cross-sectional area perpendicular to the fluid flow direction.

[0009] In one embodiment, a pressure regulating part may be further included between the first reaction part and the second reaction part.

[0010] In one embodiment, at least one of the first reaction part, the second reaction part and the discharge part may further include a temperature adjustment part.

[0011] In one embodiment, based on 100 parts by volume of the first reaction part, the capacity of the second reaction part may be 1 part by volume to 50 parts by volume.

[0012] In one embodiment, the flow rate of the fluid flow can be adjusted to a rate of 0.01 volume parts / minute to 1.00 volume parts / minute of the capacity of the first reaction part.

[0013] According to another aspect, a method for preparing a phthalonitrile compound is provided, which is a method using the preparation system as described above, and the method comprises: step (a), adding a mixture containing a phthalic acid compound and a nitrile compound to the first reaction section; step (b), transporting the mixture to the second reaction section while causing the mixture to react; and step (c), obtaining the phthalonitrile compound in the discharge section; the step (b) is performed under supercritical conditions of the nitrile compound.

[0014] In one embodiment, the phthalic acid compound may be isophthalic acid, terephthalic acid or a mixture thereof.

[0015] In one embodiment, the nitrile compound may be at least one selected from the group consisting of hydrogen cyanide, acetonitrile, acrylonitrile, butyronitrile, isobutyronitrile, pivalonitrile, succinonitrile, fumaronitrile, crotononitrile and benzonitrile.

[0016] In one embodiment, the mixture in step (a) may be composed of phthalic acid compounds and nitrile compounds.

[0017] In one embodiment, in the step (a), based on 1 part by weight of the phthalic acid compound, the content of the nitrile compound may be 1 part by weight to 500 parts by weight.

[0018] In one embodiment, in the step (a), the water content of the mixture may be less than 6,000 ppm.

[0019] In one embodiment, the step (b) may be performed at 260° C. to 350° C. and 40 bar to 200 bar.

[0020] In one embodiment, the step (b) may be performed for 1 minute to 500 minutes.

[0021] In one embodiment, the step (c) may be a step of separating and purifying the phthalonitrile compounds from the product obtained in the discharge section.

[0022] In one embodiment, the residual compound separated in the step (c) can be reused in the step (a).

[0023] Technical Effects

[0024] According to one aspect, phthalonitrile-based compounds can be directly prepared from phthalic acid-based compounds in an environmentally friendly manner.

[0025] According to another aspect, a process for producing a phthalonitrile-based compound from a phthalic acid-based compound can be performed more efficiently.

[0026] The effects of one aspect of the present specification are not limited to the effects described above, and should be understood to include all effects that can be inferred from the detailed description of the present specification or the structure of the invention described in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The gas chromatography results of the products prepared according to Comparative Example 1-2 of this specification;

[0028] Figure 2 The gas chromatography results of the products prepared according to Examples 1-2 of this specification;

[0029] Figure 3 A system for preparing phthalonitrile compounds according to a specific embodiment of the present specification is schematically shown;

[0030] Figure 4 A system for preparing phthalonitrile compounds according to another specific embodiment of the present specification is schematically shown;

[0031] Figure 5 A system for preparing phthalonitrile compounds according to another specific embodiment of the present specification is schematically shown;

[0032] Figure 6 A system for preparing phthalonitrile compounds according to another specific embodiment of the present specification is schematically shown.

[0033] Description of Reference Numerals

[0034] 100: First reaction department

[0035] 200: Second reaction unit

[0036] 300: Emissions Department

[0037] 120, 220, 320: Temperature adjustment unit

[0038] 400: Pressure regulation unit

[0039] Embodiments of the invention

[0040] One aspect of the present specification will be described below with reference to the accompanying drawings. However, the matters described in the present specification can be implemented in many different forms and should not be construed as being limited to the embodiments described herein. In the accompanying drawings, in order to clearly illustrate one aspect of the present specification, parts that are not related to the description are omitted, and the same reference numerals always indicate the same components.

[0041] Throughout the specification, when it is stated that a certain part is "connected" to other parts, this includes not only the case of "direct connection" but also the case of "indirect connection" with other components arranged in between. Furthermore, when it is stated that a certain part "includes" a certain structural element, unless there is a special statement to the contrary, this means that other structural elements are not excluded but may be included.

[0042] In this specification, when describing a series of numerical ranges, unless otherwise specifically stated, these values ​​have a precision of significant figures provided according to standard rules in chemistry for significant figures. For example, 10 includes a range of 5.0 to 14.9, and the number 10.0 includes a range of 9.50 to 10.49.

[0043] Hereinafter, one embodiment of the present specification will be described in detail with reference to the accompanying drawings.

[0044] Preparation system of phthalonitrile compounds

[0045] According to one aspect, a system for preparing phthalonitrile compounds is a system for preparing phthalonitrile compounds using a continuous process, which includes: a first reaction unit 100 filled with a mixture containing a phthalic acid compound and a nitrile compound; a second reaction unit 200 connected to the first reaction unit; and a discharge unit 300 connected to the second reaction unit; in the second reaction unit, there is a fluid flow from the first reaction unit 100 to the discharge unit 300, and the length of the second reaction unit 200 in the fluid flow direction can be more than 10 times the square root of the average cross-sectional area perpendicular to the fluid flow direction.

[0046] The first reaction unit 100 may be a tank reactor and may include a stirring unit (not shown). In the first reaction unit 100, a primary reaction of the phthalic acid-based compound and the nitrile-based compound may be started and performed.

[0047] The phthalic acid compound may be a compound having an aromatic ring and two or more carboxyl groups. In one embodiment, the phthalic acid compound may be isophthalic acid, terephthalic acid or a mixture thereof.

[0048] The nitrile compound may be one or more selected from the group consisting of hydrogen cyanide, acetonitrile, acrylonitrile, butyronitrile, isobutyronitrile, pivalonitrile, succinonitrile, fumaronitrile, crotonitrile and benzonitrile, but is not limited thereto. For example, when the nitrile compound is hydrogen cyanide, the reaction in the first reaction unit 100 and / or the second reaction unit 200 may be performed at a temperature of 183.5°C or more and a pressure of 50 bar or more. When the nitrile compound is acetonitrile, the reaction in the first reaction unit 100 and / or the second reaction unit 200 may be performed at a temperature of 272°C or more and a pressure of 48.7 bar or more. When the nitrile compound is acrylonitrile, the reaction in the first reaction unit 100 and / or the second reaction unit 200 may be performed at a temperature of 267°C or more and a pressure of 46 bar or more. When the nitrile compound is butyronitrile, the reaction in the first reaction unit 100 and / or the second reaction unit 200 may be performed at a temperature of 309°C or more and a pressure of 37.8 bar or more. When the nitrile compound is isobutyronitrile, the reaction in the first reaction unit 100 and / or the second reaction unit 200 can be performed at a temperature of 336°C or higher and a pressure of 40 bar or higher. When the nitrile compound is pivalonitrile, the reaction in the first reaction unit 100 and / or the second reaction unit 200 can be performed at a temperature of 343°C or higher and a pressure of 34.4 bar or higher. In addition, depending on the type of the nitrile compound, the reaction conditions in the first reaction unit 100 and / or the second reaction unit 200 can be changed. Therefore, the above conditions are illustrative and do not limit the scope of the matters recorded in this specification. The nitrile compound can be either a solvent or a reactant.

[0049] The second reaction unit 200 may be a tubular reactor in which the length in the direction of fluid flow is greater than the length perpendicular to the direction of fluid flow. Figures 3 to 6 The second reaction part 200 and the fluid flow direction are shown by a straight line and a thin solid arrow, but the present invention is not limited thereto. In addition to a straight line, the second reaction part 200 and the fluid flow direction may be a curve such as a coil shape.

[0050] In the present specification, the length of the second reaction part 200 refers to a distance from one end connected to the first reaction part 100 to the other end connected to the discharge part 300 through which the fluid flows.

[0051] In this specification, the cross-sectional area of ​​the second reaction part 200 refers to the area perpendicular to the flow direction of the fluid.

[0052] In this specification, when the cross-sectional area of ​​the second reaction part 200 does not change according to the position, the "square root of the average cross-sectional area" may refer to the square root value of the cross-sectional area. When the cross-sectional area of ​​the second reaction part 200 changes according to the position, the "square root of the average cross-sectional area" may refer to the square root value of the cross-sectional area. sqrt value.

[0053] [Mathematical formula]

[0054]

[0055] In the above formula, L is the length of the second reaction part 200, A(x) is the cross-sectional area value from one end (0) connected to the first reaction part 100 to the other end (L) connected to the discharge part 300, S sqrt It refers to the square root of the above average cross-sectional area.

[0056] The length of the second reaction section 200 may be more than 10 times the square root of the average cross-sectional area. For example, the length of the second reaction section 200 may be 10 times, 15 times, 20 times, 25 times, 30 times, 35 times, 40 times, 45 times, 50 times, 55 times, 60 times, 65 times, 70 times, 75 times, 80 times, 85 times, 90 times, 95 times, 100 times, 105 times, 110 times, 115 times, 120 times, 125 times, 130 times, 135 times, 140 times, 145 times, 150 times, 155 times, 160 times, 165 times, 170 times, 175 times, 180 times, 185 times, 190 times, 195 times, 200 times, 205 times, 210 times, 215 times, 220 times, 225 times, 230 times, 235 times, 240 times, 245 times, 250 times, 255 times, 260 times, 265 times, 270 times, 275 times, 280 times, 285 times, 290 times, 295 times, 300 times, 305 times, 310 times, 315 times, 320 times, 325 times, 330 times, 335 times, 340 times, 345 times, 350 times, 355 times, 360 times, 365 times, 370 times, 375 times, 380 times, 385 times, 390 times, 395 times, 400 times, 405 times, 410 times, 415 times, 420 times, 425 times, 430 times, 435 times, 440 times, 445 times, 450 times, 455 times, 460 times, 465 times, 470 times, 475 times, 480 times, 485 times, 490 times, 495 times, 500 times, 505 times, 510 times, 515 times, 520 times, 525 times, 530 times, 535 times, 540 times, 545 times, 550 times, 555 times, 560 times, 565 times, 570 times, 575 times, 580 times, 585 times, 590 times, 595 times, 600 times, 605 times, 610 times, 615 times, 620 times, 625 times, 630 times, 635 times, 640 times, 645 times, 650 times, 655 times, 660 times, 665 times, 670 times, 675 times, 680 times, 685 times, 690 times, 695 times, 700 times, 715 times, 720 times, 725 times, 730 times, 735 times, 740 times, 745 times, 750 times, 755 times, 760 times, 765 times, 770 times, 775 times, 780 times, 785 times, 790 times, 795 times, 800 times, 805 times, 810 times, 815 times, 820 times, 825 times, 830 times, 835 times, 840 times, 845 times, 850 times, 855 times, 860 times, 865 times, 870 times, 875 times, 880 times, 885 times, 890 times, 895 times, 900 times, 905 times, 910 times, 915 times, 920 times, 925 times, 930 times, 935 times, 940 times, 945 times, 950 times, 955 times, 960 times, 965 times, 970 times, 975 times, 980 times, 985 times,990 times, 995 times, 1,000 times, a range between any two of these values, or 1,000 times or more, for example, it can be 10 times to 1,000 times the square root of the average cross-sectional area, but the present invention is not limited thereto.

[0057] When the length of the second reaction unit 200 exceeds the above range, the purity of the product may be reduced due to insufficient control of the reaction temperature and / or reaction pressure, or the process may take too long, thereby reducing productivity.

[0058] Figure 3 The preparation system of the phthalonitrile compound is schematically shown, and the reaction is carried out by connecting the second reaction unit 200 as a tubular reactor to the first reaction unit 100 as a tank reactor, and the product is obtained in the discharge unit 300, thereby improving the problem of reduced purity of the product due to changes in reaction temperature and / or reaction pressure. The first reaction unit 100 and the second reaction unit 200 can adjust the amount (flow rate) of the mixture fed into the second reaction unit 200 by using a valve (not shown in the figure) such as a flow meter.

[0059] Referring to another example of the preparation system of the above-mentioned phthalonitrile compound Figure 4 A pressure regulating unit 400 may be further included between the first reaction unit 100 and the second reaction unit 200 and / or between the second reaction unit 200 and the discharge unit 300. When the pressure regulating unit 400 is further included, the reaction pressure may be further precisely controlled.

[0060] Referring to another example of the preparation system of the above-mentioned phthalonitrile compound Figure 5 At least one of the first reaction part 100, the second reaction part 200 and the discharge part 300 may further include a temperature adjustment part 120, 220, 320. The temperature adjustment part 120, 220 of the first reaction part 100 or the second reaction part 200 may help maintain a high reaction temperature in the form of surrounding each reaction part 100, 200, and the temperature adjustment part 320 of the discharge part 300 may be located at the front end of the discharge part 300 and used to cool the product, but the present invention is not limited thereto.

[0061] Referring to another example of the preparation system of the above-mentioned phthalonitrile compound Figure 6 , may include at least one of the temperature regulating parts 120, 220, 320 and at least one of the pressure regulating parts 400. The positions of the temperature regulating part 320 and the pressure regulating part 400 may be changed to each other.

[0062] Based on the capacity of the above-mentioned first reaction part 100 of 100 parts by volume, the capacity of the above-mentioned second reaction part 200 can be 1 part by volume to 50 parts by volume, for example, can be 1 part by volume, 5 parts by volume, 10 parts by volume, 15 parts by volume, 20 parts by volume, 25 parts by volume, 30 parts by volume, 35 parts by volume, 40 parts by volume, 45 parts by volume, 50 parts by volume or the range between any two values ​​in these values, but the present invention is not limited thereto. When the capacity of the above-mentioned second reaction part 200 is too large compared with the above-mentioned first reaction part 100, process efficiency may be reduced, and when the capacity of the above-mentioned second reaction part 200 is too small compared with the above-mentioned first reaction part 100, the effect of improving product purity by controlling reaction conditions may be insufficient.

[0063] The flow rate of the above-mentioned fluid flow can be adjusted to 0.01 volume parts / minute to 1.00 volume parts / minute of the capacity of the above-mentioned first reaction part 100, for example, 0.01 volume parts / minute, 0.05 volume parts / minute, 0.10 volume parts / minute, 0.15 volume parts / minute, 0.20 volume parts / minute, 0.25 volume parts / minute, 0.30 volume parts / minute, 0.35 volume parts / minute, 0.40 volume parts / minute, 0.45 volume parts / minute, 0.50 volume parts / minute, 0.55 volume parts / minute, 0.60 volume parts / minute, 0.65 volume parts / minute, 0.70 volume parts / minute, 0.75 volume parts / minute, 0.80 volume parts / minute, 0.85 volume parts / minute, 0.90 volume parts / minute, 0.95 volume parts / minute, 1.00 volume parts / minute or a rate within the range between any two of these values. When the flow rate of the above-mentioned fluid flows exceeds the above-mentioned range, the process efficiency is reduced due to the reaction time being too long, or the purity of the product is reduced due to the reaction time being too short.

[0064] Preparation method of phthalonitrile compounds

[0065] According to another aspect, a method for preparing a phthalonitrile compound is a method using the above-mentioned preparation system, and the above-mentioned method for preparing a phthalonitrile compound comprises: step (a), adding a mixture comprising a phthalic acid compound and a nitrile compound to the above-mentioned first reaction unit 100; step (b), transporting the above-mentioned mixture to the above-mentioned second reaction unit 200 while causing the above-mentioned mixture to react; and step (c), obtaining the phthalonitrile compound in the above-mentioned discharge unit 300, and the above-mentioned step (b) can be performed under the supercritical condition of the above-mentioned nitrile compound.

[0066] In the above preparation method, for example, after the mixture is put into the first reaction unit 100, the temperature is raised to 275°C to 285°C and the reaction pressure reaches 90 bar to 95 bar, and the reaction is carried out by stirring for a predetermined time, and the reactants are transported to the second reaction unit 200 and further reacted to obtain a phthalonitrile compound in the discharge unit 300, but the present invention is not limited to this.

[0067] As described above, the reaction temperature of the above-mentioned step (b) can be adjusted according to the type of the above-mentioned nitrile compound. For example, when the above-mentioned nitrile compound is hydrogen cyanide, the above-mentioned step (b) can be performed under the conditions of a temperature of 183.5°C or more and a pressure of 50 bar or more. When the above-mentioned nitrile compound is acetonitrile, the above-mentioned step (b) can be performed under the conditions of a temperature of 272°C or more and a pressure of 48.7 bar or more. When the above-mentioned nitrile compound is acrylonitrile, the above-mentioned step (b) can be performed under the conditions of a temperature of 267°C or more and a pressure of 46 bar or more. When the above-mentioned nitrile compound is butyronitrile, the above-mentioned step (b) can be performed under the conditions of a temperature of 309°C or more and a pressure of 37.8 bar or more. When the above-mentioned nitrile compound is isobutyronitrile, the above-mentioned step (b) can be performed under the conditions of a temperature of 336°C or more and a pressure of 40 bar or more. When the above-mentioned nitrile compound is pivalonitrile, the above-mentioned step (b) can be performed under the conditions of a temperature of 343°C or more and a pressure of 34.4 bar or more. In addition, the conditions of the above step (b) may be changed according to the type of the above nitrile compound. Therefore, the above conditions are illustrative and do not limit the scope of the matters described in this specification. The above nitrile compound may be a solvent or a reactant.

[0068] In the above step (a), based on 1 part by weight of the above phthalic acid compound, the content of the above nitrile compound can be 1 part by weight to 500 parts by weight. For example, based on 1 part by weight of the above phthalic acid compound, the content of the above nitrile compound can be 1 part by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, 95 parts by weight, 100 parts by weight, 105 parts by weight, 110 parts by weight, 115 parts by weight, 120 parts by weight, 125 parts by weight, 130 parts by weight, 135 parts by weight, 140 parts by weight, 145 parts by weight, 150 parts by weight, 160 parts by weight, 165 parts by weight, 170 parts by weight, 175 parts by weight, 180 parts by weight, 185 parts by weight, 190 parts by weight, 200 parts by weight, 210 parts by weight, 215 parts by weight, 220 parts by weight, 230 parts by weight, 240 parts by weight, 250 parts by weight, 260 parts by weight, 270 parts by weight, 280 parts by weight, 290 parts by weight, 300 parts by weight, 310 parts by weight, 310 parts by weight, 320 parts by weight, 330 parts by weight, 350 parts by weight, 360 parts by weight, 370 parts 0 parts by weight, 125 parts by weight, 130 parts by weight, 135 parts by weight, 140 parts by weight, 145 parts by weight, 150 parts by weight, 155 parts by weight, 160 parts by weight, 165 parts by weight, 170 parts by weight, 175 parts by weight, 180 parts by weight, 185 parts by weight, 190 parts by weight, 195 parts by weight, 200 parts by weight, 205 parts by weight, 210 parts by weight, 215 parts by weight, 220 parts by weight, 225 parts by weight, 230 parts by weight, 235 parts by weight, 240 parts by weight, 245 parts by weight, 250 parts by weight , 255 parts by weight, 260 parts by weight, 265 parts by weight, 270 parts by weight, 275 parts by weight, 280 parts by weight, 285 parts by weight, 290 parts by weight, 295 parts by weight, 300 parts by weight, 305 parts by weight, 310 parts by weight, 315 parts by weight, 320 parts by weight, 325 parts by weight, 330 parts by weight, 335 parts by weight, 340 parts by weight, 345 parts by weight, 350 parts by weight, 355 parts by weight, 360 parts by weight, 365 parts by weight, 370 parts by weight, 375 parts by weight, 380 parts by weight , 385 weight parts, 390 weight parts, 395 weight parts, 400 weight parts, 405 weight parts, 410 weight parts, 415 weight parts, 420 weight parts, 425 weight parts, 430 weight parts, 435 weight parts, 440 weight parts, 445 weight parts, 450 weight parts, 455 weight parts, 460 weight parts, 465 weight parts, 470 weight parts, 475 weight parts, 480 weight parts, 485 weight parts, 490 weight parts, 495 weight parts, 500 weight parts or the scope between any two values ​​in these values. When the content of above-mentioned nitrile compound is greater than the content of above-mentioned phthalic acid series compound, the purity of product can rise, but if above-mentioned nitrile compound is too large, it may be disadvantageous in economic aspect.

[0069] In the above step (a), the moisture content of the above mixture may be less than 6,000 ppm. For example, the moisture content of the above mixture may be less than 6,000 ppm, less than 5,000 ppm, less than 4,000 ppm, less than 3,000 ppm, less than 2,000 ppm, less than 1,000 ppm, less than 750 ppm, less than 500 ppm or less than 250 ppm. The lower the moisture content of the above mixture, the higher the purity of the product.

[0070] The reaction of the above step (b) may be di-nitrilation by a direct substitution reaction of a carboxyl group and a nitrile group, and an example thereof may be represented by the following reaction formula.

[0071]

[0072] In the above reaction formula, R is an aromatic ring such as phenylene, and R' may be an alkyl group having 1 to 20 carbon atoms, for example, methyl, ethyl, isopropyl, tert-butyl, and the like.

[0073] In the step (b), the reaction temperature is increased according to the above range, and the pressures of the first reaction unit 100, the second reaction unit 200 and the discharge unit 300 are adjusted to be within the above reaction pressure range, so that the reaction and the transport can be performed.

[0074] In the above step (b), the reaction can be carried out without a separate additive such as ammonia, high concentration oxygen or a catalyst. Since the reaction of the above step (b) can be carried out without a separate additive, the mixture of the above step (a) can be composed of a phthalic acid compound and a nitrile compound, but the present invention is not limited thereto. For example, the above mixture can be a mixture formed by dissolving a solid phthalic acid compound in a nitrile compound solvent, but the present invention is not limited thereto.

[0075] When the temperature and pressure conditions of the above-mentioned step (b) are above the critical point of the above-mentioned nitrile compound, the reaction can be carried out. The above-mentioned step (b) can be performed under 260°C to 350°C temperature and 40 bar to 200 bar pressure conditions. For example, the above-mentioned step (b) can be performed under a reaction temperature in the range of 260°C, 265°C, 270°C, 275°C, 280°C, 285°C, 290°C, 295°C, 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, 350°C or any two values ​​in these values. For example, the step (b) may be carried out at a reaction pressure of 40 bar, 45 bar, 50 bar, 55 bar, 60 bar, 65 bar, 70 bar, 75 bar, 80 bar, 85 bar, 90 bar, 95 bar, 100 bar, 105 bar, 110 bar, 115 bar, 120 bar, 125 bar, 130 bar, 135 bar, 140 bar, 145 bar, 150 bar, 155 bar, 160 bar, 165 bar, 170 bar, 175 bar, 180 bar, 185 bar, 190 bar, 195 bar, 200 bar, or any two of these values. When the reaction temperature of the step (b) is too low, the purity of the product may be reduced, or the reaction may not be carried out. When the reaction temperature of the step (b) is too high, the amount of by-products produced increases, resulting in reduced purity. When the reaction pressure of the step (b) is too low, the reaction may not proceed. When the reaction pressure of the step (b) is too high, the safety may be reduced.

[0076] When the above-mentioned system for preparing phthalonitrile-based compounds is used, the final product purity is high, the total reaction time is reduced, and the productivity is excellent by more accurately controlling the reaction temperature and pressure.

[0077] The step (b) can be performed for 1 minute to 500 minutes. For example, the step (b) can be performed for 1 minute, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes, 120 minutes, 125 minutes, 130 minutes. , 135 minutes, 140 minutes, 145 minutes, 150 minutes, 155 minutes, 160 minutes, 165 minutes, 170 minutes, 175 minutes, 180 minutes, 185 minutes, 190 minutes, 195 minutes, 200 minutes, 205 minutes, 210 minutes, 215 minutes, 220 minutes, 225 minutes, 230 minutes, 235 minutes, 240 minutes, 245 minutes, 250 minutes, 255 minutes, 26 0 minutes, 265 minutes, 270 minutes, 275 minutes, 280 minutes, 285 minutes, 290 minutes, 295 minutes, 300 minutes, 305 minutes, 310 minutes, 315 minutes, 320 minutes, 325 minutes, 330 minutes, 335 minutes, 340 minutes, 345 minutes, 350 minutes, 355 minutes, 360 minutes, 365 minutes, 370 minutes, 375 minutes, 380 minutes, 385 minutes The reaction time of step (b) can be as follows: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 40, 410, 415, 420, 425, 430, 435, 440, 445, 450, 455, 460, 465, 470, 475, 480, 485, 490, 495 or 500 minutes, and can include ranges intermediate to these values. As the reaction time of step (b) increases, the purity of the product rises, but if the reaction time is too long, the productivity may decrease.

[0078] The step (c) may be a step of separating and purifying the phthalonitrile compound from the product obtained in the discharge unit 300. The separation and purification may be separation of the phthalonitrile compound and residual compounds, which may be performed by various known methods such as distillation separation. For example, the residual compound may include one or more selected from the group consisting of unreacted phthalic acid compounds, unreacted nitrile compounds, and phthalic acid nitrile compounds in which only a part of the carboxyl groups of the phthalic acid compounds react, but the present invention is not limited thereto.

[0079] The residual compounds other than the phthalonitrile-based compounds separated in the above step (c) can be reused in the above step (a). The preparation method of the phthalonitrile-based compounds according to one embodiment of the present specification can be carried out without using a separate additive such as a catalyst, so the residual compounds can be reused without a separate purification process.

[0080] The purity of the product of the above-mentioned method for preparing phthalonitrile compounds using the above-mentioned system for preparing phthalonitrile compounds can be 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more or 95% or more.

[0081] Below, the embodiments of this specification will be described in more detail. However, the following experimental results are only representative experimental results in the above embodiments, and the scope and content of this specification cannot be narrowed or interpreted restrictively due to the embodiments, etc. Each effect in the various embodiments of this specification that is not clearly shown below will be specifically described in the corresponding part.

[0082] Reactor

[0083] First reactor: a tank reactor equipped with a stirrer and having a capacity of 100 parts by volume

[0084] Second reactor: a tubular reactor with a length of 670 times the square root of the cross-sectional area and a capacity of 6 parts by volume

[0085] Comparative Example 1

[0086] 5 parts by weight of isophthalic acid (IPA) and 100 parts by weight of acetonitrile (ACN) are added to a first reactor equipped with an agitator to form a reaction system. Nitrogen is replaced three times at a pressure of 2 to 3 bars inside the first reactor. Stirring is performed at 400 rpm under normal pressure in the first reactor and the internal temperature is raised to 290°C. The reaction is carried out for 1 to 4 hours while maintaining the reaction temperature, at which time the reaction pressure is 90 to 95 bars. After the reaction is completed, the reaction system is cooled to room temperature. Thereafter, the reaction system is subjected to reduced pressure distillation to separate acetonitrile and isophthalonitrile (IPN). Acetonitrile is reused, and the purity of the product is confirmed by analyzing isophthalonitrile by gas chromatography.

[0087] Comparative Example 2

[0088] 5 parts by weight of terephthalic acid (TPA) and 100 parts by weight of acetonitrile are added to a first reactor equipped with an agitator to form a reaction system. Nitrogen is replaced three times at a pressure of 2 to 3 bars inside the first reactor. Stirring is performed at 400 rpm under normal pressure in the first reactor and the internal temperature is raised to 290°C. The reaction is carried out for 1 to 4 hours while maintaining the reaction temperature, at which time the reaction pressure is 90 to 95 bars. After the reaction is completed, the reaction system is cooled to room temperature. Afterwards, the reaction system is subjected to reduced pressure distillation to separate acetonitrile and terephthalonitrile (TPN). Acetonitrile is reused, and the purity of the product is confirmed by gas chromatography analysis of terephthalonitrile.

[0089] Example 1

[0090] 5 parts by weight of isophthalic acid and 100 parts by weight of acetonitrile are added to a first reactor equipped with a stirrer. Nitrogen is replaced 3 times at a pressure of 2 to 3 bars inside the first reactor. Stirring is performed at 150 rpm in the first reactor and the internal temperature of the first and second reactors is raised to 275 to 285° C. The reaction is carried out for 1 hour while maintaining a reaction temperature of 275 to 285° C. and a reaction pressure of 90 to 95 bars, and then the pressure and flow are controlled and the reactants are transported through the second reactor. The product obtained at the end of the second reactor is analyzed by gas chromatography at intervals of 30 minutes to confirm the purity of the product.

[0091] Example 2

[0092] 5 parts by weight of terephthalic acid and 100 parts by weight of acetonitrile were added to a first reactor equipped with a stirrer. Nitrogen was replaced 3 times at a pressure of 2 to 3 bar inside the first reactor. Stirring was performed at 150 rpm in the first reactor and the internal temperature of the first and second reactors was raised to 280 to 300° C. The reaction was carried out for 1 hour while maintaining a reaction temperature of 280 to 300° C. and a reaction pressure of 70 to 100 bar, and then the pressure and flow were controlled and reactants were transported through the second reactor. The product obtained at the end of the second reactor was analyzed by gas chromatography at intervals of 30 minutes to confirm the purity of the product.

[0093] The reaction conditions and product purity of the above comparative examples and embodiments are summarized in Table 1 below. Also, the gas chromatography results of the products prepared according to Comparative Examples 1-2 are shown in Figure 1 The gas chromatography results of the products prepared according to Example 1-2 are shown in Figure 2 middle.

[0094] Table 1

[0095]

[0096] When comparing Comparative Example 1 which is a batch process using a first reactor and Example 1 which is a continuous process using a first reactor and a second reactor, under the same reactant and reaction temperature conditions, although the reaction time of Example 1 is only half of that of Comparative Example 1, it can be confirmed that the purity is higher.

[0097] Furthermore, when Example 2 in which terephthalonitrile was prepared by a continuous process was compared with Comparative Example 2 in which terephthalonitrile was prepared by a batch process, it was confirmed that terephthalonitrile with a higher purity could be prepared by only half to 63% of the reaction time.

[0098] Referring to Example 1-1, Example 1-2 and Example 1-6, the higher the reaction temperature, the higher the purity of the product. At a reaction temperature of 275° C., a portion of unreacted isophthalic acid was detected.

[0099] With reference to Examples 1-3 to 1-7, as the reaction time increases, the purity of the product also increases, and a high-purity product can be produced even in a reaction time that is shorter than that of a batch reactor.

[0100] With reference to Examples 1-2 and 1-8, it can be confirmed that the higher the content of the phthalic acid compound is than that of the nitrile compound, the higher the purity of the product tends to be.

[0101] Referring to the above-mentioned Example 1 and Example 2, unlike the preparation process using the existing ammoxidation reaction using harmful compounds such as ammonia and an acid catalyst, in one embodiment of the present invention, a phthalonitrile-based compound can be prepared from a phthalic acid-based compound in high yield without adding a separate catalyst or additive. In addition, a higher purity product can be prepared by a shorter reaction time than the comparative example using a continuous process for a batch reaction.

[0102] And, refer to Figure 1 and Figure 2 , unlike the comparative example in which 15 wt % to 20 wt % of the intermediate (3-CBA) remained, the residual intermediate (3-CBA) in the example was reduced to less than half.

[0103] Specifically, in the above embodiment, isophthalic acid or terephthalic acid as a phthalic acid compound is used as a reactant, and acetonitrile as an organic nitrile is used as a solvent and a reactant. Their mixture is directly heated without adding a separate catalyst or additive, thereby forming a supercritical state of high temperature and pressure (Tc: above 275°C, Pc: above 48 bar), inducing an exchange reaction between the acid and the nitrile, and directly generating a phthalonitrile compound. In addition, by dividing the above reaction into a tank reactor and a tubular reactor, a high-purity product can be prepared in a shorter time. As a result, purification and separation of the final product are easier.

[0104] The above description of this specification is only illustrative, and any person skilled in the art of one aspect of this specification will understand that it can be easily transformed into other specific forms without changing the technical ideas or essential features recorded in this specification. Therefore, the above-mentioned embodiments are only illustrative in various aspects, but are not limited to this. For example, each structural component described as a single type can also be implemented in a dispersed manner, and similarly, the structural components described using dispersed methods can also be implemented in a combined form.

[0105] The scope of the present specification is indicated by the appended claims, and all changes or modifications derived from the meaning, scope and equivalent concepts of the claims should be interpreted as being included in the scope of the present specification.

Claims

1. A method for preparing a phthalonitrile compound, which adopts a continuous process preparation system, the method comprising: Step (a), adding a mixture comprising a phthalic acid compound and a nitrile compound to the first reaction part; Step (b), transporting the mixture to a second reaction part connected to the first reaction part while reacting the mixture; and Step (c), obtaining a phthalonitrile compound in a discharge section connected to the second reaction section, The step (b) is performed under supercritical conditions of the nitrile compound. The nitrile compound is one selected from the group consisting of hydrogen cyanide, acetonitrile, acrylonitrile, butyronitrile, isobutyronitrile and pivalonitrile. When the nitrile compound is hydrogen cyanide, the reactions in the first reaction unit and the second reaction unit are performed at a temperature of 183.5° C. or higher and a pressure of 50 bar or higher; When the nitrile compound is acetonitrile, the reactions in the first reaction unit and the second reaction unit are performed at a temperature of 272° C. or higher and a pressure of 48.7 bar or higher; When the nitrile compound is acrylonitrile, the reactions in the first reaction unit and the second reaction unit are performed at a temperature of 267° C. or higher and a pressure of 46 bar or higher; When the nitrile compound is butyronitrile, the reactions in the first reaction unit and the second reaction unit are performed at a temperature of 309° C. or higher and a pressure of 37.8 bar or higher; When the nitrile compound is isobutyronitrile, the reactions in the first reaction unit and the second reaction unit are performed at a temperature of 336° C. or higher and a pressure of 40 bar or higher; When the nitrile compound is pivalonitrile, the reaction in the first reaction unit and the second reaction unit is performed at a temperature of 343° C. or higher and a pressure of 34.4 bar or higher. In the second reaction part, there is a fluid flow from the first reaction part to the discharge part. The length of the second reaction part in the fluid flow direction is 10 to 1000 times the square root of the average cross-sectional area perpendicular to the fluid flow direction.

2. The method for preparing a phthalonitrile compound according to claim 1, wherein The phthalic acid compound is isophthalic acid, terephthalic acid or a mixture thereof.

3. The method for preparing a phthalonitrile compound according to claim 1, wherein The mixture in the step (a) is composed of a phthalic acid compound and the nitrile compound.

4. The method for preparing a phthalonitrile compound according to claim 1, wherein In the step (a), the content of the nitrile compound is 1 part by weight to 500 parts by weight based on 1 part by weight of the phthalic acid compound.

5. The method for preparing a phthalonitrile compound according to claim 1, wherein: In the step (a), the moisture content of the mixture is less than 6,000 ppm.

6. The method for preparing a phthalonitrile compound according to claim 1, wherein: The above step (b) is performed for 1 minute to 500 minutes.

7. The method for preparing a phthalonitrile compound according to claim 1, wherein The step (c) is a step of separating and purifying the phthalonitrile compound from the product obtained in the discharge section.

8. The method for preparing a phthalonitrile compound according to claim 7, wherein: The residual compound separated in the above step (c) is reused in the above step (a).

9. The method for preparing a phthalonitrile compound according to claim 1, wherein: The system for preparing phthalonitrile-based compounds includes a pressure regulating unit between the first reaction unit and the second reaction unit.

10. The method for preparing a phthalonitrile compound according to claim 1, wherein: At least one of the first reaction part, the second reaction part and the discharge part further includes a temperature adjustment part.

11. The method for preparing a phthalonitrile compound according to claim 1, wherein: The capacity of the second reaction part is 1 part by volume to 50 parts by volume based on 100 parts by volume of the capacity of the first reaction part.

12. The method for preparing a phthalonitrile compound according to claim 1, wherein: The flow rate of the fluid flow is adjusted to a rate of 0.01 to 1.00 parts by volume per minute of the capacity of the first reaction part.

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