Preparation method and application of 2-alkyl anthracene

Abstract

The invention relates to the technical field of preparation of 2-alkyl anthracene, and discloses a preparation method and application of 2-alkyl anthracene, the preparation method comprises the following steps: (1) in the presence of a catalyst, anthracene and heavy alkyl anthracene are mixed for a transalkylation reaction; and (2) stopping the transalkylation reaction when the concentration of anthracene in the product of the transalkylation reaction is detected to be less than or equal to 0.2 wt% through gas chromatography, and carrying out reduced pressure distillation on the product of the transalkylation reaction to obtain a light fraction containing 2-alkylanthracene. According to the method, the alkyl anthracene mixed product basically containing no anthracene can be prepared through the transalkylation reaction of the heavy alkyl anthracene and the anthracene, and the heavy alkyl anthracene raw material solution in the reaction can simultaneously play a good role of solvent for dissolving the anthracene; and the source of device blockage caused by anthracene contained in the separation process of the alkyl anthracene mixture in the prior art is eliminated as far as possible.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of 2-alkylanthracene, and in particular to a preparation method of 2-alkylanthracene and application thereof. Background Art

[0002] At present, the main industrial technology for producing hydrogen peroxide at home and abroad is the anthraquinone process. The 2-alkylanthraquinone in this process, as the "carrier" of the process, directly affects the quality of hydrogen peroxide. The main method for producing 2-alkylanthraquinone is the phthalic anhydride method, but this process has serious pollution problems. To produce 1 ton of 2-ethylanthraquinone, 1.76 tons of AlCl 3 and 4.2 tons of oleum (20%), and both are difficult to recycle. Therefore, from the perspective of environmental protection and clean production, it is very important to develop a green production process for 2-alkylanthraquinone.

[0003] US4255343A discloses a method for synthesizing 2-tert-amyl anthracene, wherein anthracene, trichlorobenzene and methanesulfonic acid are mixed at a certain temperature and pressure, and then an olefin is introduced into the system to undergo an alkylation reaction with anthracene. The solid product is mainly the remaining anthracene and a series of alkyl anthracene products, of which anthracene accounts for 42%, 2-alkyl anthracene accounts for 47%, and the rest are anthracene disubstituted products and other by-products. The product contains a large amount of unreacted anthracene, which is difficult to separate.

[0004] CN111825545A discloses a method for separating 2-alkylanthracene from a product containing alkylanthracene and preparing 2-alkylanthraquinone by a catalytic oxidation process, wherein anthracene and an alkylating agent are subjected to an alkylation reaction to prepare a mixture containing unconverted anthracene and alkylanthracene; the reaction mixture containing anthracene and alkylanthracene is melt-crystallized to separate anthracene; and the alkylanthracene mixture from which anthracene is removed is further distilled to separate 2-alkylanthracene. The method involves steps such as melt-crystallization separation and distillation separation, and the process is complicated, and it is difficult to completely separate the unreacted raw material anthracene from the alkylanthracene mixture containing anthracene.

[0005] Due to the crystallization and high-temperature sublimation properties of anthracene, in the distillation process of alkylanthracene containing anthracene, even in trace amounts of anthracene, anthracene crystallization is very likely to occur during the fractionation process, blocking device-related channels such as condenser tubes, instrument connection pipelines, and other devices. In addition, it is very difficult to match the receiving device for the anthracene vapor condensation to directly enter the solid phase, making the industrial production of 2-alkylanthracene difficult to achieve. At the same time, a large amount of low-boiling point solvents need to be introduced into the conventional alkylation reaction, which also brings about problems of solvent recovery and low production efficiency.

[0006] In the prior art, during the alkylation reaction of anthracene with an alkylating agent, if the conversion rate of anthracene is to be further improved, a reaction ratio in which the alkylating agent is greatly in excess of anthracene is required, which will result in the generation of polyalkylated products. Although this helps to reduce the content of anthracene in the alkylation reaction product, the generation of polyalkylated products reduces the selectivity of the reaction and the yield of the target product 2-alkylanthracene. Further high-temperature and reduced-pressure distillation is performed to produce multi-stage fractions. For example, CN109704910A discloses a method for separating a mixture containing anthracene alkylation reaction products, including alkylation solvent separation, melt crystallization, and multi-stage reduced-pressure distillation. Higher temperature and vacuum degree are required, and the production device consumes too much energy, generates carbon deposits, and there is also the problem that the heavy components cannot be recycled.

[0007] Therefore, how to solve the problem of device blockage caused by the sublimation and condensation crystallization of anthracene in the distillation process from the source, while simplifying the process and reducing energy consumption, is an important issue in the industrialization of 2-alkylanthracene. Summary of the invention

[0008] The purpose of the present invention is to overcome the problems in the prior art that it is difficult to balance the conversion rate of anthracene and the yield of 2-alkylanthracene, and that the sublimation and condensation crystallization of anthracene in the distillation process cause device blockage, and to provide a preparation method of 2-alkylanthracene and its application. The preparation method has the advantages of being able to balance high anthracene conversion rate and high 2-alkylanthracene yield, and obtaining an alkylanthracene mixture with extremely low anthracene content or no anthracene, thereby eliminating the problem of device blockage caused by the anthracene content of the distillation product from the source.

[0009] In order to achieve the above object, the present invention provides a method for preparing 2-alkylanthracene, which comprises:

[0010] (1) mixing anthracene and heavy alkyl anthracene in the presence of a catalyst to carry out a transalkylation reaction;

[0011] (2) When the concentration of anthracene in the product of the transalkylation reaction is ≤0.2 wt % as detected by gas chromatography, the transalkylation reaction is stopped, and the product of the transalkylation reaction is subjected to reduced pressure distillation to obtain a light fraction containing 2-alkylanthracene.

[0012] Another aspect of the present invention provides application of the above-mentioned preparation method of 2-alkylanthracene in the preparation process of 2-alkylanthraquinone.

[0013] The preparation method provided by the present invention can prepare an alkyl anthracene mixed product substantially free of anthracene through the transalkylation reaction of heavy alkyl anthracene and anthracene, and the heavy alkyl anthracene raw material liquid in the reaction can also play a good role as a solvent for dissolving anthracene. By controlling the feed mass ratio of heavy alkyl anthracene: anthracene, the content of anthracene in the alkyl anthracene product is controlled to be ≤0.2%, and preferably the content of anthracene detected by GC is zero, which can eliminate the root cause of device blockage caused by the presence of anthracene in the separation process of the alkyl anthracene mixture in the prior art as much as possible. In the preferred case, the present invention can repeatedly recover heavy alkyl anthracene, avoid the problems of product purity, solvent recovery, excessive energy consumption, and hidden operational safety hazards brought by the use of non-anthracene homologues and low-boiling aromatic solvents, so that the cost of preparing alkyl anthracene by anthracene alkylation is greatly reduced. Since the product substantially does not contain anthracene, the problem of high operational difficulty in the anthracene-alkyl anthracene product separation process in the prior art can be significantly reduced, and the yield of the target product 2-alkyl anthracene is improved.

[0014] The method is simple in process, reasonable and feasible, has low cost, is safe and reliable, and is environmentally friendly, thus opening up a new industrialization route for the green preparation of 2-alkylanthraquinone as a carrier of hydrogen peroxide working fluid. DETAILED DESCRIPTION

[0015] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0016] In one aspect, the present invention provides a method for preparing 2-alkylanthracene, the method comprising:

[0017] (1) mixing anthracene and heavy alkyl anthracene in the presence of a catalyst to carry out a transalkylation reaction;

[0018] (2) When the concentration of anthracene in the product of the transalkylation reaction is ≤0.2 wt % as detected by gas chromatography, the transalkylation reaction is stopped, and the product of the transalkylation reaction is subjected to reduced pressure distillation to obtain a light fraction containing 2-alkylanthracene.

[0019] In the present invention, "alkylanthracene" has the conventional definition in the art, and refers to anthracene substituted with an alkyl group. "2-alkylanthracene" refers to the 2-alkylation product of anthracene, for example, it can be 2-alkylanthracene (C4-C6 alkyl), preferably 2-pentylanthracene.

[0020] In the prior art, 2-alkylanthracene is usually prepared by alkylation reaction of anthracene with alkylating agents such as hydrocarbons under acid catalysis. Generally, the progress of the reaction needs to be controlled. If the conversion rate of anthracene is too high, the content of polyalkyl substituted products of anthracene in the product increases significantly, and the selectivity of 2-alkylanthracene is too low. It is difficult to improve the conversion rate of anthracene while ensuring a certain selectivity of 2-alkylanthracene. Therefore, the conversion rate of anthracene generally needs to be controlled at 10-60%. However, it is well known in the art that if the raw material anthracene cannot be completely converted, the reaction product still contains residual anthracene. Due to the crystallization property and high-temperature sublimation property of anthracene, in the distillation process of alkylanthracene containing anthracene, even containing trace amounts of anthracene, the crystallization of anthracene is very likely to occur in the fractionation process, blocking the channels related to the device, such as the condenser tubes, instrument connection pipelines and other devices, seriously affecting the continuous and stable operation of the factory.

[0021] The inventors of the present invention creatively proposed that heavy alkyl anthracene and anthracene are used for transalkylation reaction, and the reaction conditions can be controlled to ensure that anthracene is completely converted into alkyl anthracene, so that the transalkylation product does not contain or substantially contains anthracene, and further, there is no need to separate anthracene additionally. Since the various types of alkyl anthracene in the alkyl anthracene mixture have low melting points and no crystalline properties, there is no difficulty in heat preservation of the device. The alkyl anthracene of different temperature fractions can be easily separated by traditional vacuum distillation, which greatly improves the production efficiency of the device and saves energy, and obtains the target product of 2-alkyl anthracene. The essential factor of the device blockage caused by the anthracene content in the distillation product is fundamentally eliminated.

[0022] According to the present invention, during the transalkylation reaction, the content of anthracene in the reaction mixture is monitored by gas chromatography (GC), and the transalkylation reaction is stopped when the concentration of anthracene is ≤0.2wt%, preferably, the transalkylation reaction is stopped when the concentration of anthracene is ≤0.02wt%, and more preferably, the concentration of anthracene is 0. In the present invention, when the concentration of anthracene cannot be detected by gas chromatography, the concentration of anthracene is deemed to be 0.

[0023] In the present invention, the heavy alkyl anthracene refers to a monoalkyl anthracene having a total carbon number higher than the target 2-alkyl anthracene or a polyalkyl anthracene having a total carbon number not lower than the target 2-alkyl anthracene. The heavy alkyl anthracene may be a single substance or a mixture of various alkyl anthracenes, and the present invention has no particular limitation on this.

[0024] In the present invention, preferably, the heavy alkyl anthracene includes at least one of the alkyl anthracenes with a boiling point of ≥250° C., preferably, the heavy alkyl anthracene includes at least one of the alkyl anthracenes with a boiling point of 280-350° C. In the present invention, the boiling point involved refers to the boiling point of the substance at an absolute pressure of 2.5 kPa.

[0025] Preferably, the heavy alkyl anthracene comprises a monoalkyl anthracene with a carbon number of 21-30 and / or a polyalkyl anthracene with a carbon number of 16-30; preferably, the polyalkyl anthracene comprises a combination of one or more of a dialkyl anthracene with a carbon number of 16-30, a trialkyl anthracene with a carbon number of 17-30, and a tetraalkyl anthracene with a carbon number of 18-30. Preferably, the total carbon number of the heavy alkyl anthracene is not less than 20.

[0026] Preferably, based on the total weight of the heavy alkyl anthracene, the content of C18-C20 heavy alkyl anthracene is 0.5-5wt%, the content of C22-C26 heavy alkyl anthracene is 50-60wt%, and the content of ≥C29 heavy alkyl anthracene is 40-50wt%.

[0027] The present invention has no particular requirements for the source of the heavy alkyl anthracene. Preferably, the heavy alkyl anthracene is provided by a heavy byproduct obtained by the alkylation reaction of anthracene with an alkylating agent. Preferably, it is a heavy fraction obtained by removing 2-alkyl anthracene (C4-C6), preferably 2-pentyl anthracene, from the product obtained by the alkylation reaction of anthracene with an alkylating agent.

[0028] The present invention has no particular limitation on the specific manner and conditions of the alkylation reaction of anthracene with the alkylating agent, and the alkylation reaction can be carried out in a conventional manner in the art, which is well known to those skilled in the art.

[0029] According to some preferred embodiments of the present invention, the process of the alkylation reaction of anthracene with an alkylating agent comprises: contacting anthracene with an alkylating agent under alkylation conditions and in the presence of an alkylation reaction solvent and a catalyst for alkylation reaction. The alkylating agent is selected from at least one of C2-C8 olefins, alcohols and halogenated hydrocarbons, preferably at least one of C4-C6 olefins, alcohols and halogenated hydrocarbons, more preferably C4-C6 monoolefins, and most preferably C5 olefins. The method of the alkylation reaction can refer to the operation mode and conditions of the alkylation reaction disclosed in CN11825545A.

[0030] According to the present invention, the amount of heavy alkyl anthracene added has a wide range of selection, and the amount of heavy alkyl anthracene added can be controlled to control the anthracene content in the product to be ≤0.2wt%. The heavy alkyl anthracene can be added to the reactor at once, or in stages, and the heavy alkyl anthracene can be added according to the GC detection results, and the addition method can be batch or continuous.

[0031] According to some preferred embodiments of the present invention, the mass ratio of the heavy alkyl anthracene to anthracene is (1-20):1, preferably (1-5):1, for example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1 and other specific but non-limiting mass ratios or ranges between any two. Further preferably, the mass ratio of the heavy alkyl anthracene to anthracene is (1-3):1. The use of the above preferred embodiments is conducive to improving the conversion efficiency of anthracene and facilitating the complete dissolution of anthracene, thereby helping to simplify the operation process and ensure the continuity of public welfare operations.

[0032] In the present invention, in order to make the transalkylation reaction easier to carry out, the transalkylation reaction is carried out in the presence of a catalyst. The present invention has a wide range of selection for the catalyst, and any type and form of catalyst having catalytic transalkylation reaction activity in the art can be applied to the present invention. Preferably, the catalyst is a liquid acid, preferably methanesulfonic acid and / or p-toluenesulfonic acid, more preferably methanesulfonic acid.

[0033] The present invention has no particular limitation on the amount of the catalyst, and the conventional amount in the art can be referred to. Preferably, based on the total mass of anthracene, heavy alkyl anthracene and the catalyst, the content of the catalyst is 0.1-20wt%, for example, it can be 0.1wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt% or any range between the two, preferably, based on the total mass of anthracene, heavy alkyl anthracene and the catalyst, the content of the catalyst is 1-10wt%.

[0034] Preferably, before the reduced pressure distillation, the preparation method further comprises: removing the catalyst from the product of the transalkylation reaction. The present invention does not particularly limit the specific method for removing the catalyst from the product of the transalkylation reaction, and those skilled in the art can select a conventional separation method in the art to separate the catalyst according to the properties of the catalyst.

[0035] When the catalyst is methanesulfonic acid and / or p-toluenesulfonic acid, the catalyst can be removed by, for example, sedimentation separation.

[0036] According to some preferred embodiments of the present invention, no solvent is present in the transalkylation reaction.

[0037] In the prior art anthracene alkylation reaction, low-boiling aromatic hydrocarbons are usually introduced as reaction solvents. The inventors of the present invention have found that heavy alkyl anthracenes can be directly melted and used as reaction solvents. At the same time, heavy alkyl anthracenes are also reaction raw materials, which can avoid the use of low-boiling aromatic hydrocarbon solvents, thereby avoiding the problems of recycling, energy consumption, and non-homologous by-product impurities.

[0038] The present invention has no particular requirements for the mixing method or the order of adding materials in step (1), as long as the anthracene and the catalyst can be evenly dispersed in the heavy alkyl anthracene. According to some preferred embodiments of the present invention, the mixing method in step (1) includes: heating and melting the heavy alkyl anthracene to obtain a raw material liquid, and then adding anthracene and the catalyst to the raw material liquid. The use of the above preferred embodiments helps to ensure the effective dissolution of anthracene.

[0039] Preferably, the mixing is performed under stirring conditions. The present invention has no particular limitation on the specific stirring conditions, and conventional experimental conditions can be used.

[0040] The present invention has a wide range of selection of conditions for the transalkylation reaction, as long as the concentration of anthracene in the product of the transalkylation reaction can be ensured to be ≤0.2wt%, preferably ≤0.02wt%.

[0041] According to some preferred embodiments of the present invention, the conditions of the transalkylation reaction include: reaction temperature of 100-200°C, preferably 100-170°C; reaction pressure of 0-0.2MPa, preferably 0-0.1MPa; reaction time of 0.1-48h, preferably 1-12h. The reaction pressure is gauge pressure.

[0042] Preferably, the transalkylation reaction is carried out under an inert atmosphere, which is preferably provided by nitrogen.

[0043] In the present invention, since the product of the transalkylation reaction contains substantially no anthracene or no anthracene at all, the 2-alkylanthracene in the transalkylation product has the lowest boiling point in the product mixture, and therefore, a light fraction containing 2-alkylanthracene can be directly obtained by vacuum distillation separation. The vacuum distillation can be carried out in a distillation kettle or a vacuum distillation tower, and the 2-alkylanthracene product is obtained by cutting the light fraction at the top of the tower or the top of the kettle by vacuum distillation. The present invention has a wide range of selection for the specific operating conditions of the vacuum distillation. Preferably, the conditions of the vacuum distillation include: a tower top pressure of 0-10kPa, preferably 0.01-5kPa, more preferably 0.1-2kPa; a tower top temperature of 180-360°C, preferably 210-340°C, more preferably 250-300°C.

[0044] According to the present invention, the light fraction obtained by the vacuum distillation is 2-alkylanthracene, and the bottom fraction is the heavy fraction containing heavy alkylanthracene. The heavy fraction containing heavy alkylanthracene can be used to provide the heavy alkylanthracene described in step (1). By adopting the above preferred embodiment, the heavy alkylanthracene component is effectively recycled, the high-temperature vacuum distillation process and process of alkylanthracene are further simplified, a large amount of energy is saved, and the by-product heavy alkylanthracene fraction produced by the reaction is effectively utilized. At the same time, the cost of the process for preparing alkylanthracene by anthracene alkylation is greatly reduced, and the operation is simpler and easier.

[0045] In the present invention, there is no special requirement for the number of vacuum distillations. Vacuum distillations can be performed 1-2 times according to actual product needs to obtain fraction cutting (or composition) components. Since further vacuum distillation requires a higher temperature, it will cause side reactions such as carbon deposition in the distillation apparatus, consume a lot of energy, and the operating conditions are more stringent. In the present invention, it is preferred to perform only one vacuum distillation.

[0046] In the present invention, since the heavy alkyl anthracene fractions except 2-alkyl anthracene in the products of the transalkylation reaction are all by-products, the present invention can completely recycle the heavy alkyl anthracene fractions, and therefore, it is not necessary to further perform multi-stage distillation of higher boiling point fractions at a higher temperature, and the heavy fractions after the 2-alkyl anthracene is removed can be directly reused as reaction solvents and raw materials, saving a lot of energy and operation time, while helping to avoid carbon deposition of hydrocarbons at high temperatures and the difficulty of operating the device, and most importantly, it is conducive to improving the production efficiency of the target product and completely recycling the by-products.

[0047] According to a particularly preferred embodiment of the present invention, the method for preparing 2-alkylanthracene comprises:

[0048] (1) mixing anthracene and heavy alkyl anthracene in the presence of a catalyst to carry out a transalkylation reaction;

[0049] Wherein, the heavy alkyl anthracene comprises at least one of the alkyl anthracenes with a boiling point of ≥250°C; no solvent is present in the transalkylation reaction; the mass ratio of the heavy alkyl anthracene to anthracene is (0.5-20):1;

[0050] (2) stopping the transalkylation reaction when the concentration of anthracene in the product of the transalkylation reaction is ≤0.2 wt % by gas chromatography, and subjecting the product of the transalkylation reaction to reduced pressure distillation to obtain a light fraction containing 2-alkyl anthracene and a heavy fraction containing heavy alkyl anthracene;

[0051] (3) recycling the heavy fraction containing heavy alkyl anthracene to step (1) to provide the heavy alkyl anthracene.

[0052] Another aspect of the present invention provides application of the above-mentioned preparation method of 2-alkylanthracene in the preparation process of 2-alkylanthraquinone.

[0053] The present invention will be described in detail below through examples.

[0054] Example 1

[0055] The composition of heavy alkyl anthracene is shown in Table 1.

[0056] Table 1

[0057] Components Content wt% C18-C20 2％ C22-C26 55％ ≥C29 43％

[0058] (1) At room temperature, 356 g of heavy alkyl anthracene was added to a 2 L stirred kettle, heated to 135° C., 178 g of anthracene and 13.5 g of methanesulfonic acid were added according to a mass ratio of heavy alkyl anthracene to anthracene of 2:1, and a transalkylation reaction was carried out under stirring. The reaction was carried out at normal pressure and 135° C. for 20 h. The concentration of anthracene in the product was less than 0.02 wt % as determined by gas chromatography (GC), and the reaction was terminated.

[0059] (2) After the reaction product is separated from the catalyst by sedimentation, it is sent to a vacuum distillation tower for vacuum distillation, with a tower top pressure of ≤1 kPa, and a fraction with a tower top temperature of 250-280° C. is cut to obtain a 2-alkyl anthracene product (C4-C6). The residue at the bottom of the tower is a heavy alkyl anthracene mixture, which is returned to step (1) as a new heavy alkyl anthracene raw material. 240 g of the tower top fraction is collected, and 294 g of the tower bottom fraction is collected. The yield of 2-alkyl anthracene (C4-C6) is calculated to be 45 wt%.

[0060] in,

[0061] Yield (%) of 2-alkylanthracene (C4-C6) = weight of top fraction / (weight of top fraction+weight of bottom fraction)×100%.

[0062] Example 2

[0063] The composition of heavy alkyl anthracene is shown in Table 2.

[0064] Table 2

[0065]

[0066]

[0067] (1) at room temperature, 356 g of heavy alkyl anthracene was added to a 2 L stirred kettle, heated to 165° C., 178 g of anthracene and 17.8 g of methanesulfonic acid were added according to a mass ratio of heavy alkyl anthracene to anthracene of 2:1, and a transalkylation reaction was carried out under stirring. The reaction was carried out at normal pressure and 165° C. for 10 h. The concentration of anthracene in the product was less than 0.02 wt % as determined by gas chromatography (GC), and the reaction was terminated.

[0068] (2) After the reaction product is separated from the catalyst by sedimentation, it is sent to a vacuum distillation tower for vacuum distillation, with a tower top pressure of ≤1 kPa, and a fraction with a tower top temperature of 250-280° C. is cut to obtain a 2-alkyl anthracene product (C4-C6). The residue at the bottom of the tower is a heavy alkyl anthracene mixture, which is returned to step (1) as a new heavy alkyl anthracene raw material. 256 g of the tower top fraction and 278 g of the tower bottom fraction are collected, and the yield of 2-alkyl anthracene (C4-C6) is calculated to be 48 wt%.

[0069] Example 3

[0070] The composition of the heavy alkyl anthracene used is the same as that in Example 1.

[0071] (1) At room temperature, 534 g of heavy alkyl anthracene was added to a 2 L stirred kettle, heated to 165° C., 178 g of anthracene and 21.3 g of methanesulfonic acid were added according to a mass ratio of heavy alkyl anthracene to anthracene of 3:1, and a transalkylation reaction was carried out under stirring. The reaction was carried out at normal pressure and 165° C. for 8 h. The concentration of anthracene in the product was less than 0.02 wt % as determined by gas chromatography (GC), and the reaction was terminated.

[0072] (2) After the reaction product is separated from the catalyst by sedimentation, it is sent to a vacuum distillation tower for vacuum distillation, with a tower top pressure of ≤1 kPa, and a fraction with a tower top temperature of 250-280° C. is cut to obtain a 2-alkyl anthracene product (C4-C6). The residue at the bottom of the tower is a heavy alkyl anthracene mixture, which is returned to step (1) as a new heavy alkyl anthracene raw material. 249 g of the tower top fraction and 320 g of the tower bottom fraction are collected, and the yield of 2-alkyl anthracene (C4-C6) is calculated to be 35 wt%.

[0073] Example 4

[0074] The composition of the heavy alkyl anthracene used is the same as that in Example 1.

[0075] The method of Example 1 is followed, except that the amount of heavy alkyl anthracene added is 1000 g, the mass ratio of heavy alkyl anthracene to anthracene is about 6:1, the reaction is carried out at normal pressure and 135°C for 20 hours, and the concentration of anthracene in the product is less than 0.02wt% as determined by gas chromatography (GC), and the reaction is terminated.

[0076] After the reaction product is separated from the catalyst by sedimentation, it is sent to a vacuum distillation tower for vacuum distillation, with a tower top pressure of ≤1 kPa, and a fraction with a tower top temperature of 250-280° C. is cut to obtain a 2-alkyl anthracene product (C4-C6). The residue at the bottom of the tower is a heavy alkyl anthracene mixture, which is returned to step (1) as a new heavy alkyl anthracene raw material. 210 g of the tower top fraction and 968 g of the tower bottom fraction are collected, and the yield of 2-alkyl anthracene (C4-C6) is calculated to be 18 wt%.

[0077] Example 5

[0078] The composition of the heavy alkyl anthracene used is the same as that in Example 1.

[0079] The method of Example 1 was followed, except that the reaction temperature was 125° C. After 30 hours of reaction, the concentration of anthracene in the product was less than 0.02 wt % as determined by gas chromatography (GC), and the reaction was terminated.

[0080] After the reaction product is separated from the catalyst by sedimentation, it is sent to a vacuum distillation tower for vacuum distillation, with a tower top pressure of ≤1 kPa, and a fraction with a tower top temperature of 250-280° C. is cut to obtain a 2-alkyl anthracene product (C4-C6). The residue at the bottom of the tower is a heavy alkyl anthracene mixture, which is returned to step (1) as a new heavy alkyl anthracene raw material. 160 g of the tower top fraction and 374 g of the tower bottom fraction are collected, and the calculated yield of 2-alkyl anthracene (C4-C6) is 29%.

[0081] Example 6

[0082] The composition of the heavy alkyl anthracene used is the same as that in Example 1.

[0083] The method of Example 1 was followed, except that after 10 hours of reaction, the concentration of anthracene in the product was 0.11 wt % as determined by gas chromatography (GC), and the reaction was terminated.

[0084] After the reaction product is separated from the catalyst by sedimentation, it is sent to a vacuum distillation tower for vacuum distillation, with a tower top pressure of ≤1 kPa, and a fraction with a tower top temperature of 250-280° C. is cut to obtain a 2-alkyl anthracene product (C4-C6). The residue at the bottom of the tower is a heavy alkyl anthracene mixture, which is returned to step (1) as a new heavy alkyl anthracene raw material. 165 g of the tower top fraction and 369 g of the tower bottom fraction are collected, and the calculated yield of 2-alkyl anthracene (C4-C6) is 31%.

[0085] It can be seen from the above examples that in the embodiments of the present invention, a mixed alkyl anthracene reaction product containing 2-alkyl anthracene is generated by the transalkylation reaction of heavy alkyl anthracene to anthracene, and further, a 2-monoalkyl anthracene light fraction and a heavy alkyl anthracene heavy fraction are easily obtained by conventional vacuum distillation. Since the distilled reaction mixture does not contain anthracene, the device blockage caused by the unreacted anthracene in the kettle top fraction is completely avoided. Since the present invention does not require further vacuum distillation at a higher temperature after obtaining the light fraction, it can avoid the carbon deposition of the device materials, greatly reduce the production energy consumption, and simplify the harsh process flow. The present invention directly uses heavy alkyl anthracene as a raw material liquid, avoids the method of preparing alkyl anthracene using low-boiling aromatic hydrocarbons as a reaction solvent in the prior art, greatly improves the equipment utilization rate, realizes the inherent safety production of the device, greatly improves the production efficiency, reduces the production cost, and completely recycles the heavy components in the reaction mixture. There is no by-product impurity generated by non-anthracene homologues, and the product quality is significantly improved.

[0086] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing 2-alkylanthracene, characterized in that: The preparation method comprises: (1) mixing anthracene and heavy alkyl anthracene in the presence of a catalyst to carry out a transalkylation reaction; (2) When the concentration of anthracene in the product of the transalkylation reaction is ≤0.2 wt % as detected by gas chromatography, the transalkylation reaction is stopped, and the product of the transalkylation reaction is subjected to reduced pressure distillation to obtain a light fraction containing 2-alkylanthracene.

2. The preparation method according to claim 1, wherein The heavy alkyl anthracene comprises at least one of the alkyl anthracenes having a boiling point of ≥250°C, preferably, the heavy alkyl anthracene comprises at least one of the alkyl anthracenes having a boiling point of 280-350°C; Preferably, the heavy alkyl anthracene comprises a monoalkyl anthracene having a carbon number of 18-30 and / or a polyalkyl anthracene having a carbon number of 16-30; the polyalkyl anthracene is preferably at least one of a dialkyl anthracene having a carbon number of 16-30, a trialkyl anthracene having a carbon number of 17-30, and a tetraalkyl anthracene having a carbon number of 18-30; Preferably, the heavy alkyl anthracene is provided by a heavy component byproduct obtained by reacting anthracene with an alkylating agent; Preferably, the alkylating agent is selected from at least one of C2-C8 olefins, alcohols and halogenated hydrocarbons.

3. The preparation method according to claim 1 or 2, wherein The mass ratio of the heavy alkyl anthracene to anthracene is (1-20):1, preferably (1-5):1, and more preferably (1-3):

1.

4. The preparation method according to any one of claims 1 to 3, wherein The catalyst is a liquid acid, preferably methanesulfonic acid and / or p-toluenesulfonic acid; Preferably, based on the total mass of anthracene, heavy alkyl anthracene and catalyst, the content of the catalyst is 0.1-20wt%, preferably 1-10wt%; Preferably, no solvent is present in the transalkylation reaction.

5. The preparation method according to any one of claims 1 to 4, wherein: The mixing method in step (1) includes: heating and melting heavy alkyl anthracene to obtain a raw material liquid, and then adding anthracene and a catalyst to the raw material liquid; Preferably, the mixing is performed under stirring conditions.

6. The preparation method according to any one of claims 1 to 5, wherein: The conditions of the transalkylation reaction include: reaction temperature of 100-200°C, preferably 100-170°C; reaction pressure of 0-0.2MPa, preferably 0-0.1MPa; reaction time of 0.1-48h, preferably 1-20h; Preferably, the transalkylation reaction is carried out under an inert atmosphere, which is preferably provided by nitrogen.

7. The preparation method according to any one of claims 1 to 6, wherein: When the concentration of anthracene in the product of the transalkylation reaction is ≤0.02 wt % as detected by gas chromatography, the transalkylation reaction is stopped, and the product of the transalkylation reaction is subjected to reduced pressure distillation; Preferably, before the reduced pressure distillation, the preparation method further comprises: removing the catalyst in the product of the transalkylation reaction.

8. The preparation method according to any one of claims 1 to 7, wherein: The conditions for the reduced pressure distillation include: a tower top pressure of 0-10 kPa, preferably 0.01-5 kPa, more preferably 0.1-2 kPa; a tower top temperature of 180-360°C, preferably 210-340°C, more preferably 250-300°C.

9. The preparation method according to any one of claims 1 to 8, wherein: A light fraction containing 2-alkyl anthracene and a heavy fraction containing heavy alkyl anthracene are obtained by the reduced pressure distillation; The heavy fraction containing heavy alkyl anthracene is used to provide the heavy alkyl anthracene described in step (1).

10. Use of the method for preparing 2-alkylanthracene according to any one of claims 1 to 9 in the preparation process of 2-alkylanthraquinone.

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