Methods for chlorinating aromatic compounds

Abstract

This invention relates to a method for chlorinating aromatic compounds, and more particularly to a method for chlorinating aromatic compounds that prevents reduced responsiveness due to foaming and prevents backflow of the fluid. In the method for chlorinating aromatic compounds according to the invention, a plurality of column reactors are connected in series such that reaction products generated in one reactor are introduced into the next reactor, and chlorine gas is introduced to the bottom of each reactor to an equal extent. Therefore, a chlorination reaction occurs in each reactor, and hydrogen chloride gas generated in each reactor is discharged from each reactor.

Description

Technical Field

[0001] The present invention relates to a method for chlorinating aromatic compounds, and more particularly to a method for chlorinating aromatic compounds that can prevent the decrease in reactivity caused by foaming and prevent backflow of fluid. Background Technology

[0002] Chlorobenzene or chlorotoluene is a material used in various industrial fields and is formed through the chlorination reaction of aromatic compounds such as benzene and toluene. As a specific example, monochlorotoluene, such as o-chlorotoluene and p-chlorotoluene, can be prepared by reacting toluene and chlorine in the presence of a catalyst such as FeCl3. Specifically, when toluene and chlorine react in the presence of a catalyst, the chlorine atom undergoes substitution to produce monochlorotoluene, such as o-chlorotoluene and p-chlorotoluene.

[0003] Conventionally, when aromatic compounds are chlorinated as described above to prepare chlorobenzene or chlorotoluene, over-chlorination byproducts, such as dichlorobenzene or dichlorotoluene, may be generated depending on the supply ratio of the aromatic compound and chlorine. To minimize the generation of byproducts, in common production methods, an excess of benzene or toluene is used compared to chlorine, and a large amount of unreacted benzene or toluene mixed with the products after the reaction is recovered and reused as a reactant.

[0004] However, as with common production methods, even when using large amounts of benzene or toluene compared to chlorine, significant amounts of byproducts such as dichlorobenzene or dichlorotoluene are generated, thus the selectivity and yield do not increase beyond a certain level.

[0005] To address such problems in the prior art, in Korean Patent Registration No. 10-1759512 previously filed by the applicant, toluene and chlorine were reacted in a reactor having a multi-stage structure (including a reaction unit and a cooling unit) to improve the selectivity of chlorotoluene and p-chlorotoluene, thereby increasing the reaction yield.

[0006] However, in reactors with multi-stage structures, as the chlorination reaction occurs, the gas ratio increases over time, and the residence time of chlorine decreases towards the top, making it difficult to control the linear velocity of the gas in the reactor. Specifically, as the reaction time progresses, the linear velocity of the gas in the reactor increases, and exceeding a certain linear velocity generates foam, thereby reducing reactivity and ultimately decreasing the yield.

[0007] Therefore, the inventors have conducted in-depth research on an effective method to improve product yield by maintaining high reactivity even as chlorination reaction time passes. Summary of the Invention

[0008] Technical issues

[0009] One object of the present invention is to provide a method for chlorinating aromatic compounds, which can prevent the decrease in reactivity caused by foaming and prevent backflow of liquid in the reactor.

[0010] Technical solution

[0011] In one general aspect, a method for chlorinating an aromatic compound includes: introducing reaction products generated in a preceding reactor into a subsequent reactor in a plurality of column reactors connected in series; introducing the same amount of chlorine gas into the lower part of each reactor to carry out a chlorination reaction in each reactor; and discharging hydrogen chloride gas generated in each reactor from each reactor.

[0012] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, the reaction products generated in the previous reactor can be cooled by a heat exchanger disposed between adjacent reactors and quantitatively introduced into the lower part of the subsequent reactor.

[0013] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, hydrogen chloride gas can be further discharged from the reaction products generated in the previous reactor through a buffer drum, and then the reaction products can be supplied to the next reactor.

[0014] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, chlorine gas may be introduced into the lower part of a reactor via a gas distributor disposed in each reactor and having a plurality of holes formed thereon.

[0015] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, the diameter of the orifice of the gas distributor can be from 1 mm to 5 mm.

[0016] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, chlorine gas can be introduced through a gas distributor orifice at a linear velocity of 5 m / s to 10 m / s.

[0017] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, the aromatic compound and chlorine gas may be introduced in a ratio of 1:1 / 16 to 1:1 / 8 based on the total molar amount.

[0018] In a method for chlorinating aromatic compounds according to an exemplary embodiment of the present invention, the conversion rate in each reactor can be from 1% to 15%.

[0019] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, the aromatic compound is introduced into the lower part of the reactor through a raw material supply nozzle disposed in a portion of the reactor lower than the gas distributor, and the aromatic compound can be introduced through the raw material supply nozzle at a linear velocity of 10 m / s to 40 m / s.

[0020] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, the linear velocity of the gas in each reactor may be 7 cm / s or less.

[0021] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, the reaction product may be cooled to a temperature of 0°C or higher and 25°C or lower by a heat exchanger.

[0022] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, the diameter of the chlorine gas bubbles introduced into each reactor may be 0.1 mm or larger and 5 mm or smaller.

[0023] In a method for chlorinating aromatic compounds according to an exemplary embodiment of the present invention, the reaction in each reactor can be carried out in the presence of a main catalyst and a co-catalyst.

[0024] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, the main catalyst may be at least one selected from FeCl3, ferrocene, PtO2, SbCl3 and Fe.

[0025] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, the co-catalyst is selected from S2Cl2, thiamethoxam, diphenylselenide, and tetrachlorophene. At least one of tetrachlorophenoxathin, dichlorothiathane, tetrachlorothiathane, and polychlorothiathane.

[0026] In a method for chlorinating an aromatic compound according to an exemplary embodiment of the present invention, the content of the main catalyst and the co-catalyst (main catalyst: co-catalyst) can be 1:0.59 or greater and 1:0.76 or less, based on the molar ratio.

[0027] Beneficial effects

[0028] In the method for reacting aromatic compounds according to the invention, the same amount of chlorine gas is supplied to a plurality of reactors arranged in series, and the reaction products generated in the previous reactor are supplied to the next reactor, thereby preventing foaming and reduced chlorination reactivity due to the increase in gas volume with reaction time, and thus increasing the reaction yield of the product to be prepared.

[0029] Furthermore, the conversion rate of reaction products is improved, thereby reducing the formation of waste materials such as chlorine as unreacted reactants and hydrogen chloride (HCl) as a reaction byproduct, and thus providing an environmentally friendly and economical method for reacting aromatic compounds. Attached Figure Description

[0030] Figure 1 This is an exemplary schematic diagram of a reaction apparatus used in a method for chlorinating aromatic compounds according to an exemplary embodiment of the present invention. Detailed Implementation

[0031] Unless otherwise defined herein, all terms used in this specification (including technical and scientific terms) may have the meanings commonly understood by those skilled in the art. Throughout this specification, unless otherwise specifically stated, the phrase "comprising" of a component shall be understood to mean that other components are also included, without excluding any other components. Furthermore, unless otherwise specifically stated, the singular forms herein include the plural forms.

[0032] The terms “about,” “substantially,” etc., used in this specification are used in a numerical sense or in a sense close to the numerical sense when they indicate that the unique manufacturing and materials allow for tolerances, and are intended to prevent unfair use by unreasonably infringing parties of the disclosure which mentions standards or absolute values ​​for the purpose of better understanding this application.

[0033] In this specification, the term "combination thereof" included in the Markush format means a mixture of one or more of the constituent elements described in the Markush format, and means including one or more of the constituent elements.

[0034] Conventionally, when aromatic compounds are chlorinated to prepare chlorobenzene or chlorotoluene, over-chlorination byproducts, such as dichlorobenzene or dichlorotoluene, are produced depending on the supply ratio of the aromatic compound and chlorine. Therefore, the aim is to improve the reaction yield and selectivity for o-chlorotoluene and p-chlorotoluene by reacting toluene and chlorine in a reactor with a multi-stage structure (including reaction and cooling units). However, because the chlorination reaction occurs in a multi-stage reactor, the gas ratio increases over time, causing the residence time of chlorine to decrease towards the top, and making it difficult to control the linear velocity of the gas in the reactor. Therefore, as the reaction time progresses, the linear velocity exceeds a certain level, leading to foaming and thus reducing the yield.

[0035] In this invention, a plurality of column reactors are connected in series, such that the reaction products generated in one reactor are introduced into the next, an equal amount of chlorine gas is introduced into the lower part of each reactor to carry out the chlorination reaction in each reactor, and the hydrogen chloride gas generated in each reactor is discharged from each reactor. Therefore, foaming and reduced chlorination reactivity due to gas volume increase caused by the passage of reaction time are prevented, thereby improving the reaction yield of the product to be prepared.

[0036] Furthermore, the improved product conversion rate reduces the generation of waste materials such as chlorine as unreacted reactants and hydrogen chloride (HCl) as a reaction byproduct, thus providing an environmentally friendly and economical method for reacting aromatic compounds.

[0037] Specifically, in a plurality of reactors arranged in series, the reaction products generated in the first reactor, which is located at the very front and in which chlorine is first supplied to the raw material containing aromatic compounds, can be supplied to the next reactor adjacent to it, and then sequentially supplied through each reactor to the reactor located at the last stage.

[0038] In each reactor, chlorine is injected into the reaction products (i.e., raw materials containing aromatic compounds) generated in the previous stage of the reaction to produce products through the chlorination reaction of aromatic compounds and chlorine.

[0039] In one exemplary embodiment of the invention, the aromatic compound may be benzene or toluene, and the product may be its chlorinated product, but they are not limited thereto. In a specific example, chlorine may be supplied to toluene, which is an aromatic compound, to produce o-chlorotoluene and p-chlorotoluene. More specifically, an excess of the aromatic compound may be supplied to the interior of each reactor, wherein, as a specific example, "excess" means an environment in which toluene is present in an amount greater than the stoichiometric equivalence ratio (1:1) of toluene and chlorine, which are reactants in the following reaction formula 1. Thus, in this environment, all the chlorine to be injected may react with toluene.

[0040] The step of supplying chlorine gas to toluene to produce o-chlorotoluene and p-chlorotoluene can be carried out by a reaction represented by the following reaction formula 1:

[0041] [Reaction Formula 1]

[0042]

[0043] Thus, because hydrogen chloride gas is included in the final product, the chlorination reaction of the aromatic compounds of the present invention has an increasing gas ratio as the reaction proceeds, and foaming may occur due to the increased linear velocity of the gas in the reactor. Therefore, the yield of the final product may be affected.

[0044] In this invention, since the hydrogen chloride gas produced in each reactor is discharged to the top, the hydrogen chloride gas is removed from the reaction products when the reaction products are supplied from the previous reactor to the next stage. Of course, in addition to hydrogen chloride gas, unreacted chlorine gas can also be discharged.

[0045] This invention prevents foaming caused by the increase in gas linear velocity due to the increase in gas volume in the reactor over time. Furthermore, because a constant gas linear velocity can be maintained in each reactor, the linear velocity is easily controlled, which facilitates the design and maintenance of the production process. Additionally, it prevents backflow when supplying liquids, such as raw materials, due to the increase in gas volume inside the reactor.

[0046] In one exemplary embodiment of the invention, the reaction product generated in the preceding reactor can be supplied to the subsequent reactor after further venting hydrogen chloride gas through a buffer tank disposed between adjacent reactors. As the buffer tank, a buffer tank for removing hydrogen chloride gas in the art can be used, forming a containment space capable of holding the reaction product from which hydrogen chloride gas has already been vented for the first time in the preceding reactor, and for a second venting of hydrogen chloride gas to remove as much hydrogen chloride gas as possible from the reaction product. The reaction product from which hydrogen chloride gas has been removed for the second time can be supplied to the subsequent reactor within the buffer tank. Therefore, when the reaction product from the preceding reactor is supplied to the subsequent reactor through the buffer tank, hydrogen chloride gas in the reaction product can be removed for the second time, thus producing a high-purity product, and also making it easier to adjust the linear velocity of the gas in the reactor.

[0047] Meanwhile, since the reaction between aromatic compounds and chlorine is exothermic, the temperature of the reaction solution increases as the reaction proceeds. Therefore, the more chlorine gas introduced into excess toluene, the more the reaction proceeds, and the higher the temperature of the reaction solution rises. Because the selectivity of the chlorination products of aromatic compounds, such as o-chlorotoluene and p-chlorotoluene, tends to decrease with increasing reaction temperature, the selectivity may decrease if the reaction proceeds too far.

[0048] Therefore, in one exemplary embodiment of the invention, the reaction products generated in the preceding reactor can be cooled and quantitatively introduced into the lower part of the following reactor via a heat exchanger disposed between adjacent reactors. Cooling can be carried out at a temperature of 0°C or higher and about 50°C or lower, specifically 5°C or higher and 30°C or lower, but cooling can be carried out without limitation, as long as the chlorine does not liquefy. Specifically, depending on the chlorine supply pressure, the temperature can be 25°C at 7.81 bara, and the temperature can be 10°C when the chlorine supply pressure is 5.07 bara. When the chlorine supply pressure is 3.7 bara, cooling can be carried out at 0°C. However, to lower the chlorine temperature, a refrigerant with a temperature lower than the cooling temperature is required, and exceeding the required cooling leads to excessive investment. Therefore, considering the chlorine liquefaction temperature, operating costs, etc., which depend on the operating pressure, the above ranges may be preferred. However, the invention is not limited thereto.

[0049] In one exemplary embodiment of the invention, chlorine injection can be performed using a gas distributor disposed in each reactor and having a plurality of orifices formed thereon. Specifically, the gas distributor is disposed in the lower part of the reactor interior and introduces chlorine into the lower part of the reactor interior. The gas distributor is not limited and any gas distributor can be used, provided it is applicable in the art. The diameter of the orifice (nozzle) of the gas distributor from which chlorine is injected can be from 0.5 mm to 5 mm, specifically from 1 mm to 3 mm, but is not limited thereto. However, the linear velocity of the chlorine can be easily set within this range.

[0050] Chlorine gas can be supplied in the same quantity in each reactor and can be introduced (injected) through the gas distributor orifice at a linear velocity of 1 m / s to 20 m / s, specifically 5 m / s to 10 m / s. Because chlorine gas is injected at such a linear velocity, a linear velocity of 1 cm / s to 7 cm / s can be observed in the reactor, and the linear velocity decreases upwards in the column reactor, thus solving the problems of reduced reaction rate and foaming caused by gas particle aggregation.

[0051] Based on the total molar amount of excess toluene in the raw materials (reaction solution) containing aromatic compounds, the amount of chlorine in the reactor can be less than 1 / 8. More specifically, it can be greater than 1 / 16 and less than 1 / 8, or 1 / 14 or greater and 1 / 10 or less, but is not limited thereto. However, by introducing chlorine within the above range, the reaction between toluene and chlorine can proceed with high selectivity throughout the process.

[0052] The diameter of the chlorine gas bubbles to be injected can be 0.1 mm or larger and 5 mm or smaller. Preferably, the chlorine gas to be injected into the reaction solution has a uniform size distribution. When the chlorine gas bubbles are too small, the reactivity of the by-products may increase, thereby reducing selectivity. When the chlorine gas bubble diameter is too large, the reactivity of the chlorine gas decreases, making the reactor size need to be large, and therefore, process costs such as investment and operating costs may increase unnecessarily.

[0053] In one exemplary embodiment of the invention, the injection of aromatic compounds can be performed via a feed nozzle disposed in a portion of each reactor lower than the gas distributor. The feed material containing the aromatic compounds can be supplied to the portion of the reactor below the chlorine gas level via the feed nozzle disposed in the portion below the gas distributor. The diameter of the orifice (nozzle) of the feed nozzle from which the aromatic compounds are sprayed can be from 1 mm to 9 mm, specifically from 1 mm to 5 mm, but is not limited thereto. The aromatic compounds can be introduced via the feed nozzle at a linear velocity of 10 m / s to 60 m / s, specifically from 10 m / s to 40 m / s, but is not limited thereto. However, within this range, the linear velocity of the liquid in the reactor can be observed, as described later.

[0054] In the reactor, the average liquid linear velocity can be 0.1 cm / s or greater and 100 cm / s or less. Within this range, adjusting the residence time of the reactants in the reactor allows for the expression of excellent reactivity.

[0055] Specifically, as a method to increase the liquid linear velocity inside the reactor for effective heat removal (cooling), increasing the flow inside the reactor causes backmixing through countercurrent, thereby reducing selectivity. Furthermore, when the linear velocity of chlorine is increased by increasing the liquid linear velocity, the chlorine conversion rate is less than 100%, and the chlorine consumption increases. When the chlorine conversion rate is low, it is difficult to separate hydrogen chloride gas and chlorine gas, which are reaction products, and therefore, chlorine gas is treated as a large amount of waste.

[0056] Because the aromatic compounds and chlorine are supplied within the aforementioned range, the gas in the reactor in this invention has a constant linear velocity, and reduced selectivity and chlorine waste due to backmixing can be prevented. Specifically, the linear velocity of the gas inside each reactor can be 10 cm / s or less, more specifically 4 cm / s or less. Since foaming is significantly suppressed within this range, the product can be produced in high yield. In this document, the gas may include hydrogen chloride gas produced by the reaction and chlorine gas in the reactor.

[0057] In one exemplary embodiment of the invention, chlorine gas can be introduced at a rate of 5 L / min to 10 L / min in a reactor with an inner diameter of 13 cm and a height of 600 cm, based on an aromatic compound introduced at a rate of 650 g / min. The conversion rate in each reactor is in the range of 1% to 15%, and excellent conversion rates can be observed.

[0058] In one exemplary embodiment of the present invention, the reaction can be carried out in the presence of a main catalyst and a co-catalyst. Specifically, the main catalyst can be one or more selected from FeCl3, ferrocene, PtO2, SbCl3, and Fe. The co-catalyst can be selected from S2Cl2, thiaanthracene, diphenylselenide, and tetrachlorophene. One or more of thiamethoxam, dichlorothiathane, tetrachlorothiathane, and polychlorothiathane.

[0059] Furthermore, based on the molar ratio, the content of the main catalyst and the co-catalyst (main catalyst: co-catalyst) can be 1:0.59 or greater and 1:0.76 or less. This is a condition for increasing the selectivity of o-chlorotoluene and p-chlorotoluene to about 99.5% or higher, as recognized with reference to Korean Patent Application No. 10-2016-0069830, which is the prior invention of the inventor.

[0060] Although the content of the main catalyst and co-catalyst of the present invention is not limited to the range described, when this technology is applied to the present invention, the effect of improving selectivity can be further enhanced.

[0061] In a chlorination method according to an exemplary embodiment of the present invention, the products can be separated and recovered after the reaction is completed in the last reactor. In addition to the desired products, unreacted aromatic compounds, excess chlorination byproducts, the main catalyst, and the co-catalyst remain after the reaction of aromatic compounds with chlorine, and therefore need to be separated for reuse. This separation can be performed using various methods known in the art.

[0062] In the following text, reference will be made to Figure 1 A specific example of a reaction method according to an exemplary embodiment of the present invention is described, such as in the case of a plurality of reactors connected in series.

[0063] First, six identical column reactors are arranged in a row parallel to the ground, with buffer tanks and heat exchangers placed between them. As shown in the attached diagram, a buffer tank can also be placed in the stage following the last reactor.

[0064] In addition, raw materials containing chlorine and excess aromatic compounds are introduced through a gas distributor and a raw material supply nozzle located in the front-stage reactor, respectively.

[0065] The chlorination method of the present invention can be carried out by passing the chlorination reaction in each reactor sequentially from the first reactor to the last reactor.

[0066] In the following description, it is assumed that the reactor located in the first stage is referred to as the first reactor 11, the reactor located in the next adjacent stage is referred to as the second reactor 12, the reactors located in the next adjacent stages up to the last stage are referred to as the first reactor to the sixth reactor 11, 12, 13, 14, 15 and 16 respectively, and in this way, the buffer tanks are referred to as the first buffer tanks to the sixth buffer tanks 21, 22, 23, 24, 25 and 16, and the heat exchangers are referred to as the first heat exchangers to the fifth heat exchangers 31, 32, 33, 34 and 35.

[0067] The reaction products generated in the first reactor 11 can undergo a first removal of hydrogen chloride gas from the first reactor 11, followed by a second removal of hydrogen chloride gas through the first buffer tank 21. Afterwards, it can be supplied to the first heat exchanger 31, cooled by the first heat exchanger 31, and then supplied to the second reactor 12. In this way, it can pass through the second reactor to the fifth reactors 12, 13, 14, and 15, the second buffer tank to the fifth buffer tanks 22, 23, 24, and 25, and the second heat exchanger to the fifth heat exchangers 32, 33, 34, and 35, and finally be supplied to the sixth reactor 16. The reaction products that finally complete the reaction in the sixth reactor 16 can be passed through the sixth buffer tank 26 to remove hydrogen chloride.

[0068] Chlorine gas is supplied equally to each of the first through sixth reactors 11, 12, 13, 14, 15, and 16, and in each reactor, the introduced chlorine gas is reacted with a raw material containing an aromatic compound or a reaction product supplied from the previous reactor to produce a chlorinated product. The reaction products supplied to each reactor are passed through the first through fifth heat exchangers 31, 32, 33, 34, and 35 to be cooled to 0°C or higher and 25°C or lower. The reason for cooling to the stated temperature range is as described above.

[0069] Preferred embodiments and comparative examples of the present invention will be described below. However, the following embodiments are merely preferred exemplary implementations of the present invention, and the present invention is not limited thereto.

[0070] (Example 1)

[0071] Toluene and chlorine gas were introduced into a reactor with an inner diameter of 13 cm and a height of 600 cm. The linear velocity of the gas in the reactor was adjusted as follows: chlorine gas was introduced at a linear velocity of 5 m / s to 10 m / s through a gas distributor orifice, and the raw material containing toluene was introduced at a linear velocity of 10 m / s to 40 m / s through a raw material supply nozzle. At this point, the molar ratio of toluene to chlorine was 2:1. FeCl3 was used as the catalyst, and S2Cl2 was used as the co-catalyst, with concentrations of 300 ppm for FeCl3 and 150 ppm for S2Cl2.

[0072] Subsequently, the gas retention rate, which is the gas volume fraction in the total gas-liquid phase, was measured. The surface area was measured by the bubble size and the gas retention rate in the reactor to determine whether foam formation occurred in the reactor. The chlorine bubbles in the distributor nozzles were injected with a size of 2 mm. The results are shown in Table 1 below.

[0073] [Table 1]

[0074]

[0075] Referring to Table 1, it was determined that almost no foam is formed at a linear velocity of 4 or less.

[0076] (Example 2)

[0077] Toluene is introduced at a rate of 650 g / min and chlorine at a rate of 5 L / min into a reactor with an inner diameter of 13 cm and a height of 600 cm. Chlorine is supplied at a rate of 7 m / s through a gas distributor orifice, and toluene is supplied at a rate of 20 m / s through a liquid distributor orifice.

[0078] The linear velocity of the gas in the reactor is 1.77 cm / s.

[0079] At this point, the toluene conversion rate is calculated using the following formula 1:

[0080] (Calculation Formula 1)

[0081] Toluene conversion rate = (supply amount - toluene after reaction) / supply amount

[0082] In Example 2, the toluene conversion rate was determined to be 2.7%, which is the theoretical conversion rate. Therefore, it is determined that the chlorination reaction in this invention is very easy to design.

[0083] While the invention has been described above with reference to specific details, exemplary embodiments, and accompanying drawings, these are provided only to aid in the overall understanding of the invention. Therefore, the invention is not limited to the exemplary embodiments. Various modifications and changes can be made by those skilled in the art based on this description.

[0084] Therefore, the spirit of the present invention should not be limited to the above exemplary embodiments, and the appended claims and all modifications identical or equivalent to the claims are intended to fall within the scope and spirit of the present invention.

Claims

1. A method for chlorinating an aromatic compound, the method comprising: In a series of multiple column reactors, the reaction products generated in the previous reactor are introduced into the next reactor. The same amount of chlorine gas is introduced into the lower part of each reactor to carry out the chlorination reaction in each reactor, and The hydrogen chloride gas produced in each of the reactors is discharged from each reactor. The aromatic compound mentioned therein is toluene.

2. The method for chlorinating an aromatic compound according to claim 1, wherein the reaction product generated in the preceding reactor is cooled by a heat exchanger disposed between adjacent reactors and quantitatively introduced into the lower part of the subsequent reactor.

3. The method for chlorinating an aromatic compound according to claim 1, wherein the hydrogen chloride gas is further discharged from the reaction product generated in the preceding reactor by means of a buffer tank disposed between adjacent reactors, and then the reaction product is supplied to the subsequent reactor.

4. The method for chlorinating an aromatic compound according to claim 1, wherein the chlorine gas is introduced into the lower part of the reactor through a gas distributor, the gas distributor being disposed in each reactor and having a plurality of holes formed thereon.

5. The method for chlorinating an aromatic compound according to claim 4, wherein the diameter of the orifice of the gas distributor is 1 mm to 5 mm.

6. The method for chlorinating an aromatic compound according to claim 4, wherein the chlorine gas is introduced through the orifice of the gas distributor at a linear velocity of 5 m / s to 10 m / s.

7. The method for chlorinating an aromatic compound according to claim 1, wherein the aromatic compound and the chlorine gas are introduced at a ratio of 1:1 / 16 to 1:1 / 8 based on the total molar amount.

8. The method for chlorinating aromatic compounds according to claim 7, wherein the conversion rate in each reactor is 1% to 15%.

9. The method for chlorinating an aromatic compound according to claim 4, wherein the aromatic compound is introduced into a lower portion of the reactor via a liquid distributor disposed in a portion of the reactor lower than the gas distributor and having orifices of a plurality of raw material supply nozzles formed thereon, and The aromatic compound is introduced through the raw material supply nozzle at a linear velocity of 10 m / s to 40 m / s.

10. The method for chlorinating aromatic compounds according to claim 1, wherein the linear velocity of the gas in each reactor is 47 cm / s or less.

11. The method for chlorinating an aromatic compound according to claim 2, wherein the reaction product is cooled to a temperature of 0°C or higher and 25°C or lower via the heat exchanger.

12. The method for chlorinating an aromatic compound according to claim 10, wherein the chlorine gas introduced into each of the reactors has a bubble diameter of 0.1 mm or greater and 5 mm or less.

13. The method for chlorinating aromatic compounds according to claim 1, wherein the reaction in each of the reactors is carried out in the presence of a main catalyst and a co-catalyst.

14. The method for chlorinating an aromatic compound according to claim 13, wherein the main catalyst is selected from at least one of FeCl3, ferrocene, PtO2, SbCl3 and Fe.

15. The method for chlorinating aromatic compounds according to claim 13, wherein the co-catalyst is selected from S2Cl2, thiamethoxam, diphenylselenide, and tetrachlorophene. At least one of thiamethoxam, dichlorothiathane, tetrachlorothiathane, and polychlorothiathane.

16. The method for chlorinating an aromatic compound according to claim 13, wherein the content of the main catalyst and the co-catalyst is 1:0.59 or greater and 1:0.76 or less, based on a molar ratio.

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