Separation method of anthracene alkylation reaction product
Anthracene and alkylanthracene are separated by azeotropic distillation and cooling crystallization technology, which solves the problem of pipeline blockage caused by the easy sublimation of anthracene, achieves efficient and stable separation effects, and improves the yield and purity of anthracene and alkylanthracene.
Patent Information
- Application Number
- CN202510648964.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-20
- Publication Date
- 2025-09-16
AI Technical Summary
In existing alkylanthracene separation methods, anthracene is easy to sublime and has high boiling and melting points, which leads to pipeline blockage during the distillation process, affecting the stable operation of the process, and making it difficult to ensure the yield and purity of anthracene and alkylanthracene.
Azeotropic distillation is used to separate anthracene and alkylanthracene by adding a specific entrainer to form an azeotrope with anthracene, combined with cooling crystallization technology, to avoid the precipitation of anthracene in the pipeline and improve the yield and purity.
The pipeline blockage problem was effectively alleviated, the system was able to operate stably for a long time, and the yield and purity of anthracene and alkylanthracene were improved.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of alkylanthracene production, in particular to a method for separating anthracene alkylation reaction products. Background Art
[0002] The anthraquinone process is the primary route for hydrogen peroxide production. Alkyl anthraquinone, a key "carrier" in this process, has a composition and purity that directly impacts the quality and yield of the hydrogen peroxide product. The traditional phthalic anhydride process for producing alkyl anthraquinones is plagued by equipment corrosion and severe environmental pollution, making it difficult to meet the requirements of a sustainable green economy. Therefore, the development of new, green processes for alkyl anthraquinone production is crucial.
[0003] The oxidation of alkylanthracenes to produce alkylanthraquinones is a feasible and promising process. This process is simple, utilizes a wide range of raw materials, and minimizes environmental pollution, making it the most promising alternative to the phthalic anhydride process. The key raw material, alkylanthracene, can be obtained through the alkylation reaction of anthracene with an alkylating agent under specific catalytic conditions. Following anthracene alkylation, the reaction solution undergoes a series of separation techniques before being oxidized with an oxidizing agent to yield the alkylanthraquinone.
[0004] Existing methods for separating alkylanthracenes primarily rely on distillation or rectification (e.g., patent CN109704910A). A thorough analysis of the composition and physical properties of anthracene alkylation products reveals that both anthracene and alkylanthracenes are polycyclic aromatic hydrocarbons with high boiling and melting points. Conventional distillation not only consumes a lot of energy, but also, due to anthracene's unique properties (such as easy sublimation and high boiling and melting points), can easily clog the distillation pipeline during the distillation process, affecting the continuous and stable operation of the process. Therefore, it is necessary to develop an efficient technology for separating anthracene alkylation reaction products that can effectively prevent pipeline clogging and achieve efficient and stable separation of the alkylation reaction products. Summary of the Invention
[0005] To address the problem of pipeline blockage during the separation of anthracene alkylation products by distillation or rectification, the present invention provides a method for separating anthracene alkylation reaction products. This separation method enables long-term stable system operation while achieving high anthracene and alkylanthracene yields and purities.
[0006] The specific technical solutions of the present invention are: A method for separating anthracene alkylation reaction products comprises the following steps: S1: pretreating the anthracene alkylation reaction product to remove part of the anthracene to obtain a pretreated product; S2: mixing the pretreated product and the entrainer, and performing distillation at 100-250° C. and 1-120 kPa to obtain a light component I and a heavy component I; the light component I comprises an azeotrope of the reaction solvent and the entrainer in the anthracene alkylation reaction product; S3: distilling the heavy component I at 100-300° C. and 0.5-100 kPa to obtain a light component II and a heavy component II; the light component II contains an azeotrope of anthracene and the entrainer; S4: Cooling and crystallizing the heavy component II, and performing solid-liquid separation to obtain alkyl anthracene.
[0007] The distillation pressures involved in the present invention are all absolute pressures.
[0008] The present invention is to separate the anthracene alkylation product as follows: in step S1, a portion of anthracene can be recovered by pretreatment, and the feed liquid includes unrecovered anthracene, alkyl anthracene and reaction solvent. In step S2, the reaction solvent can be removed by adding an entrainer and performing rectification under certain temperature and pressure conditions. The obtained light component I includes an azeotrope formed by the reaction solvent and the entrainer (the content in the light component I can reach 99.0wt% and above), and the heavy component I includes anthracene, alkyl anthracene and a small amount of entrainer. In step S3, the heavy component I is further distilled under certain temperature and pressure conditions to separate anthracene and alkyl anthracene. The obtained light component II includes an azeotrope formed by anthracene and the entrainer (the content in the light component II can reach 99.0wt% and above), and the heavy component II includes alkyl anthracene, a small amount of entrainer and other impurities. In step S4, the alkyl anthracene can be separated from the heavy component II by cooling crystallization.
[0009] In the process of separating anthracene and alkylanthracene by conventional distillation or rectification mode, due to the characteristics of anthracene easy to sublime, boiling point and melting point are higher, it is impossible to maintain a stable fluid state, and in the place where the temperature such as the pipeline wall is lower than the rectification temperature, it is easy to precipitate into a solid form, causing the pipeline to be easily blocked. In the present invention, by adding a specific entrainer, anthracene and alkylanthracene are separated by azeotropic distillation. After the entrainer forms an azeotrope with anthracene, anthracene is not easy to sublime, and the azeotrope can keep the state of a homogeneous fluid in the pipeline, thus effectively alleviating the occurrence of pipeline blockage phenomenon, so that the anthracene alkylation reaction product separation system can be stably operated for a long time, while also improving the yield and purity of anthracene and alkylanthracene. Moreover, the entrainer used in the present invention can be separated from anthracene and alkylanthracene by the mode of temperature reduction crystallization, so that the introduction of the entrainer will not cause the purification difficulty of anthracene and alkylanthracene to increase, and the anthracene and alkylanthracene yield and purity obtained by separation decrease.
[0010] Preferably, after step S3, the light component II is subjected to cooling crystallization and solid-liquid separation to obtain anthracene.
[0011] By cooling and crystallizing the light component II, anthracene and the entrainer can be separated, thereby recovering anthracene with higher purity.
[0012] Furthermore, the cooling rate for crystallizing the light component II is 1-25°C / h (further preferably 5-20°C / h), and the end point temperature is 40-80°C (further preferably 50-70°C); alternatively, the cooling rate for crystallizing the light component II is 20-100°C / h, and the end point temperature is 40-80°C (further preferably 50-70°C). After completing the crystallization and solid-liquid separation, the obtained solid component is washed with 40-80°C hot water to obtain anthracene.
[0013] Preferably, the specific process of step S1 includes: cooling and crystallizing the anthracene alkylation reaction product, removing the solid phase, and obtaining the liquid phase as the pretreatment product.
[0014] Furthermore, in step S1, the cooling crystallization process is carried out in the presence of seed crystals; the seed crystals are at least one of anthracene, ethylanthracene, butylanthracene and pentylanthracene, and the amount used is 0.2-2% of the mass of the anthracene alkylation reaction product; the terminal temperature of the cooling crystallization is 5-20°C.
[0015] Preferably, the specific process of step S1 includes: subjecting the anthracene alkylation reaction product to vacuum distillation at 150-300° C. and 0.5-150 kPa, and obtaining a heavy fraction as a pretreatment product.
[0016] Preferably, in step S2, the entrainer includes at least one of alkanes, aromatic hydrocarbons, alcohols, esters and ethers, wherein the alkane is at least one of C8-C18 straight-chain alkanes and branched alkanes, the aromatic hydrocarbon is at least one of benzene and an alkyl substituent of benzene in which the sum of the number of carbon atoms in all substituents is 2-10, the alcohol is at least one of methanol, ethanol, glycerol, diethylene glycol, triethylene glycol and tetraethylene glycol, the ester is at least one of methyl acetate, methyl benzoate, butyl acetate and phenyl acetate, and the ether is at least one of methyl ether, ethyl ether, dimethyl ether and sulfolane.
[0017] Furthermore, in step S2, the entrainer is glycerol or diethylene glycol, the distillation temperature is 150-180°C, and the pressure is 30-55 kPa; in step S3, the distillation temperature is 166-178°C, and the pressure is 7-12 kPa.
[0018] Furthermore, in step S2, the entrainer is glycerol and diethylene glycol in a mass ratio of 0.1-1:1, the distillation temperature is 150-180°C, and the pressure is 10-55kPa; in step S3, the distillation temperature is 165-180°C, and the pressure is 7-20kPa.
[0019] When the above two-component composition is used as an azeotropic agent, the glycerol therein tends to form an azeotrope with the reaction solvent in the anthracene alkylation reaction product and is separated during the distillation process in step S2. The diethylene glycol tends to form an azeotrope with anthracene and is separated during the distillation process in step S3. Compared to the solution using a single azeotropic agent, the combined use of the above two components as an azeotropic agent can improve the selective separation of the reaction solvent and anthracene, thereby increasing the purity and yield of the recovered anthracene.
[0020] Preferably, in step S2, the amount of the entrainer is 10-30 times the volume of the feed liquid.
[0021] Furthermore, in step S2, the amount of the entrainer is 18-25 times the volume of the feed liquid.
[0022] Preferably, the specific process of step S4 includes: The heavy component II is subjected to cooling crystallization at a cooling rate of 1-25°C / h (more preferably 5-20°C / h) and an end point temperature of 40-80°C (more preferably 50-70°C), followed by solid-liquid separation to obtain alkyl anthracene; or, The heavy component II is cooled and crystallized at a cooling rate of 20-100°C / h and an end point temperature of 40-80°C (more preferably 50-70°C), followed by solid-liquid separation. The obtained solid component is washed with 40-80°C hot water to obtain alkyl anthracene.
[0023] Preferably, in step S1, the reaction solvent in the anthracene alkylation reaction product is at least one of benzene and an alkylated substituent of benzene in which the sum of the carbon atoms in all substituents is 3-10.
[0024] Furthermore, in step S1, the reaction solvent in the anthracene alkylation reaction product is at least one of benzene, o-xylene, p-xylene, m-xylene, mesitylene, unsymmetrical trimethylolene and tetramethylbenzene.
[0025] Preferably, in step S4, the alkyl anthracene is at least one of ethyl anthracene, butyl anthracene, pentyl anthracene and hexyl anthracene.
[0026] Compared with the prior art, the present invention has the following advantages: (1) The present invention can alleviate the occurrence of distillation pipeline blockage by introducing a specific entrainer, thereby enabling the system to maintain stable operation for a long time, while also improving the yield and purity of anthracene and alkyl anthracene.
[0027] (2) The entrainer used in the present invention can be separated from anthracene and alkyl anthracene by crystallization through cooling, thereby not increasing the difficulty of purifying anthracene and alkyl anthracene after distillation, and not causing a decrease in the yield and purity of anthracene and alkyl anthracene. DETAILED DESCRIPTION
[0028] The present invention will be further described below with reference to the embodiments.
[0029] Overall embodiment A method for separating anthracene alkylation reaction products comprises the following steps: S1: pretreating the anthracene alkylation reaction product to remove part of the anthracene to obtain a pretreated product; S2: mixing the pretreated product and the entrainer, and performing distillation at 100-250° C. and 1-120 kPa to obtain a light component I and a heavy component I; the light component I comprises an azeotrope of the reaction solvent and the entrainer in the anthracene alkylation reaction product; S3: distilling the heavy component I at 100-300° C. and 0.5-100 kPa to obtain a light component II and a heavy component II; the light component II contains an azeotrope of anthracene and the entrainer; S4: Cooling and crystallizing the heavy component II, and performing solid-liquid separation to obtain alkyl anthracene.
[0030] In some specific embodiments, in step S1, the reaction solvent in the anthracene alkylation reaction product is at least one of benzene and an alkylated substituent of benzene in which the sum of the carbon atoms in all substituents is 3-10.
[0031] In some specific embodiments, step S1 includes: cooling and crystallizing the anthracene alkylation reaction product, removing the solid phase, and obtaining a liquid phase as the pretreatment product. Optionally or preferably, the cooling and crystallization process is performed in the presence of seed crystals; the seed crystals are at least one of anthracene, ethylanthracene, butylanthracene, and pentylanthracene, and the amount used is 0.2-2% of the mass of the anthracene alkylation reaction product; and the endpoint temperature of the cooling and crystallization is 5-20°C.
[0032] In some other specific embodiments, the specific process of step S1 includes: subjecting the anthracene alkylation reaction product to vacuum distillation at 150-300° C. and 0.5-150 kPa, and obtaining a heavy fraction as a pretreated product.
[0033] In some specific embodiments, in step S2, the entrainer includes at least one of an alkane, an aromatic hydrocarbon, an alcohol, an ester and an ether, wherein the alkane is at least one of a C8-C18 straight-chain alkane and a branched-chain alkane, the aromatic hydrocarbon is at least one of benzene and an alkyl substituent of benzene in which the sum of the number of carbon atoms in all substituents is 2-10, the alcohol is at least one of methanol, ethanol, glycerol, diethylene glycol, triethylene glycol and tetraethylene glycol, the ester is at least one of methyl acetate, methyl benzoate, butyl acetate and phenyl acetate, and the ether is at least one of methyl ether, ethyl ether, dimethyl ether and sulfolane.
[0034] Optionally, as a specific embodiment, in step S2, the entrainer is glycerol or diethylene glycol, the distillation temperature is 150-180°C, and the pressure is 30-55kPa; in step S3, the distillation temperature is 166-178°C, and the pressure is 7-12kPa. As another specific embodiment, in step S2, the entrainer is glycerol and diethylene glycol in a mass ratio of 0.1-1:1, the distillation temperature is 150-180°C, and the pressure is 10-55kPa; in step S3, the distillation temperature is 165-180°C, and the pressure is 7-20kPa.
[0035] In some specific embodiments, in step S2, the amount of the entrainer is 10-30 times the volume of the feed liquid.
[0036] In some specific embodiments, after step S3, the light component II is subjected to cooling crystallization at a cooling rate of 1-25°C / h and an end point temperature of 40-80°C, followed by solid-liquid separation to obtain anthracene.
[0037] In other specific embodiments, after step S3, the light component II is cooled and crystallized at a cooling rate of 20-100°C / h and an end point temperature of 40-80°C, followed by solid-liquid separation, and the obtained solid component is washed with 40-80°C hot water to obtain anthracene.
[0038] In some specific embodiments, the specific process of step S4 includes: cooling and crystallizing the heavy component II at a cooling rate of 1-25°C / h and an end temperature of 40-80°C, and then solid-liquid separation to obtain alkyl anthracene.
[0039] In other specific embodiments, the specific process of step S4 includes: cooling and crystallizing the heavy component II at a cooling rate of 20-100°C / h and an end temperature of 40-80°C, followed by solid-liquid separation, and washing the obtained solid component with 40-80°C hot water to obtain alkyl anthracene.
[0040] In some specific embodiments, in step S4, the alkyl anthracene is at least one of ethyl anthracene, butyl anthracene, pentyl anthracene and hexyl anthracene. Specific embodiments The present invention is described below by way of specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, any changes and advantages that can be imagined by those skilled in the art are included in the present invention, and the scope of protection of the present invention is defined by the appended claims and any equivalents thereof.
[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used herein are conventional in the art and can be obtained from conventional commercial sources. The methods used herein are conventional in the art, unless otherwise specified.
[0043] Example 1 A method for separating anthracene alkylation reaction products (the reaction product of anthracene and tert-amyl alcohol to prepare amyl anthracene by alkylation, wherein the reaction solvent used is mesitylene) comprises the following steps: S1: The anthracene alkylation reaction product is transferred to a crystallization kettle, anthracene is added as a seed crystal in an amount of 1% of the mass of the anthracene alkylation reaction product, the temperature is lowered to 20°C for crystallization, and then filtered to obtain a solid phase and a feed liquid.
[0044] S2: The feed liquid obtained in step S1 is mixed with the entrainer glycerol in a volume ratio of 1:12, and the mixture is conveyed together to a first vacuum azeotropic distillation tower for distillation at a temperature of 159° C. and a pressure of 55 kPa to obtain a light component I and a heavy component I.
[0045] S3: The heavy component I obtained in step S2 is transferred to a second vacuum azeotropic distillation tower and distilled at a temperature of 175° C. and a pressure of 10 kPa to obtain a light component II and a heavy component II.
[0046] S4: Cooling the light component II obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain anthracene.
[0047] S5: Cooling the heavy component II obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain amylanthracene.
[0048] Example 2 A method for separating anthracene alkylation reaction products (the reaction product of anthracene and tert-amyl alcohol to prepare amyl anthracene by alkylation, wherein the reaction solvent used is mesitylene) comprises the following steps: S1: The anthracene alkylation reaction product is transported to a vacuum distillation tower and distilled at a temperature of 260° C. and a distillation pressure of 30 kPa to obtain a light component I and a heavy component I.
[0049] S2: The heavy component I obtained in step S1 is mixed with the entrainer diethylene glycol in a volume ratio of 1:13, and the mixture is transferred to a first vacuum azeotropic distillation tower for distillation at a temperature of 164° C. and a pressure of 50 kPa to obtain a light component II and a heavy component II.
[0050] S3: The heavy component II obtained in step S2 is transferred to a second vacuum azeotropic distillation tower and distilled at a temperature of 175° C. and a pressure of 12 kPa to obtain a light component III and a heavy component III.
[0051] S4: Cooling the light component III obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain anthracene.
[0052] S5: Cooling the heavy component III obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain amylanthracene.
[0053] Example 3 A method for separating anthracene alkylation reaction products (the reaction product of anthracene and tert-amyl alcohol to prepare amyl anthracene by alkylation, wherein the reaction solvent used is mesitylene) comprises the following steps: S1: The anthracene alkylation reaction product is transferred to a crystallization kettle, anthracene is added as a seed crystal in an amount of 1% of the mass of the anthracene alkylation reaction product, the temperature is lowered to 20°C for crystallization, and then filtered to obtain a solid phase and a feed liquid.
[0054] S2: The feed liquid obtained in step S1 is mixed with the entrainer diethylene glycol in a volume ratio of 1:18, and the mixture is conveyed together to a first vacuum azeotropic distillation tower for distillation at a temperature of 154° C. and a pressure of 40 kPa to obtain a light component I and a heavy component I.
[0055] S3: The heavy component I obtained in step S2 is transferred to a second vacuum azeotropic distillation tower and distilled at a temperature of 178° C. and a pressure of 8 kPa to obtain a light component II and a heavy component II.
[0056] S4: Cooling the light component II obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain anthracene.
[0057] S5: Cooling the heavy component II obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain amylanthracene.
[0058] Example 4 A method for separating anthracene alkylation reaction products (the reaction product of anthracene and tert-amyl alcohol to prepare amyl anthracene by alkylation, wherein the reaction solvent used is mesitylene) comprises the following steps: S1: The anthracene alkylation reaction product is transferred to a crystallization kettle, anthracene is added as a seed crystal in an amount of 1% of the mass of the anthracene alkylation reaction product, the temperature is lowered to 20°C for crystallization, and then filtered to obtain a solid phase and a feed liquid.
[0059] S2: The feed liquid obtained in step S1 is mixed with the entrainer diethylene glycol in a volume ratio of 1:16, and the mixture is conveyed together to a first vacuum azeotropic distillation tower for distillation at a temperature of 150° C. and a pressure of 30 kPa to obtain a light component I and a heavy component I.
[0060] S3: The heavy component I obtained in step S2 is transferred to a second vacuum azeotropic distillation tower and distilled at a temperature of 166° C. and a pressure of 7 kPa to obtain a light component II and a heavy component II.
[0061] S4: Cooling the light component II obtained in step S3 to 60° C. at a rate of 100° C. / h for crystallization, and then filtering. Washing the obtained filter cake with hot water at 60° C. and drying to obtain anthracene.
[0062] S5: Cooling the heavy component II obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain amylanthracene.
[0063] Example 5 A method for separating anthracene alkylation reaction products (the reaction product of anthracene and tert-amyl alcohol to prepare amyl anthracene by alkylation, wherein the reaction solvent used is mesitylene) comprises the following steps: S1: The anthracene alkylation reaction product is transferred to a crystallization kettle, anthracene is added as a seed crystal in an amount of 1% of the mass of the anthracene alkylation reaction product, the temperature is lowered to 20°C for crystallization, and then filtered to obtain a solid phase and a feed liquid.
[0064] S2: The feed liquid obtained in step S1 is mixed with the entrainer diethylene glycol in a volume ratio of 1:13, and the mixture is conveyed together to a first vacuum azeotropic distillation tower for distillation at a temperature of 159° C. and a pressure of 55 kPa to obtain a light component I and a heavy component I.
[0065] S3: The heavy component I obtained in step S2 is transferred to a second vacuum azeotropic distillation tower and distilled at a temperature of 175° C. and a pressure of 10 kPa to obtain a light component II and a heavy component II.
[0066] S4: Cooling the light component II obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain anthracene.
[0067] S5: The heavy component II obtained in step S3 is cooled to 60° C. at a rate of 100° C. / h for crystallization, and then filtered. The filter cake is washed with hot water at 60° C. and dried to obtain amylanthracene.
[0068] Example 6 The only difference between this example and Example 4 is that the type of entrainer is changed in step S2, and the distillation temperature and pressure in steps S2 and S3 are adjusted accordingly to achieve the purpose of distillation. Specifically, in this example, the method for separating the anthracene alkylation reaction product (the reaction product of anthracene and tert-amyl alcohol to prepare amyl anthracene through alkylation, wherein the reaction solvent used is mesitylene) is as follows: S1: The anthracene alkylation reaction product is transferred to a crystallization kettle, anthracene is added as a seed crystal in an amount of 1% of the mass of the anthracene alkylation reaction product, the temperature is lowered to 20°C for crystallization, and then filtered to obtain a solid phase and a feed liquid.
[0069] S2: The feed liquid obtained in step S1 is mixed with an entrainer (glycerol and diethylene glycol with a mass ratio of 0.1:1) in a volume ratio of 1:16, and then conveyed together to a first vacuum azeotropic distillation tower, and distilled at a temperature of 175°C and a pressure of 10 kPa to obtain a light component I and a heavy component I.
[0070] S3: The heavy component I obtained in step S2 is transferred to a second vacuum azeotropic distillation tower and distilled at a temperature of 175° C. and a pressure of 10 kPa to obtain a light component II and a heavy component II.
[0071] S4: Cooling the light component II obtained in step S3 to 60° C. at a rate of 100° C. / h for crystallization, and then filtering. Washing the obtained filter cake with hot water at 60° C. and drying to obtain anthracene.
[0072] S5: Cooling the heavy component II obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain amylanthracene.
[0073] Example 7 The only difference between this example and Example 4 is that the type of entrainer is changed in step S2, and the distillation temperature and pressure in steps S2 and S3 are adjusted accordingly to achieve the purpose of distillation. Specifically, in this example, the method for separating the anthracene alkylation reaction product (the reaction product of anthracene and tert-amyl alcohol to prepare amyl anthracene through alkylation, wherein the reaction solvent used is mesitylene) is as follows: S1: The anthracene alkylation reaction product is transferred to a crystallization kettle, anthracene is added as a seed crystal in an amount of 1% of the mass of the anthracene alkylation reaction product, the temperature is lowered to 20°C for crystallization, and then filtered to obtain a solid phase and a feed liquid.
[0074] S2: The feed liquid obtained in step S1 is mixed with an entrainer (glycerol and diethylene glycol in a mass ratio of 1:1) in a volume ratio of 1:16, and then conveyed together to a first vacuum azeotropic distillation tower, and distilled at a temperature of 178°C and a pressure of 10 kPa to obtain a light component I and a heavy component I.
[0075] S3: The heavy component I obtained in step S2 is transferred to a second vacuum azeotropic distillation tower and distilled at a temperature of 175° C. and a pressure of 10 kPa to obtain a light component II and a heavy component II.
[0076] S4: Cooling the light component II obtained in step S3 to 60° C. at a rate of 100° C. / h for crystallization, and then filtering. Washing the obtained filter cake with hot water at 60° C. and drying to obtain anthracene.
[0077] S5: Cooling the heavy component II obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain amylanthracene.
[0078] Comparative Example 1 This comparative example differs from Example 1 only in that the entrainer glycerol is not added in step S2, and the distillation temperature and pressure in steps S2 and S3 are adjusted accordingly to achieve the purpose of distillation. Specifically, in this comparative example, the method for separating the anthracene alkylation reaction product (the reaction product of anthracene and tert-amyl alcohol to prepare amyl anthracene by alkylation, wherein the reaction solvent used is mesitylene) is as follows: S1: The anthracene alkylation reaction product is transferred to a crystallization kettle, anthracene is added as a seed crystal in an amount of 1% of the mass of the anthracene alkylation reaction product, the temperature is lowered to 20°C for crystallization, and then filtered to obtain a solid phase and a feed liquid.
[0079] S2: The feed liquid obtained in step S1 is conveyed to a first vacuum azeotropic distillation tower, and distilled at a temperature of 163° C. and a pressure of 60 kPa to obtain a light component I and a heavy component I.
[0080] S3: The heavy component I obtained in step S2 is transferred to a second vacuum azeotropic distillation tower and distilled at a temperature of 210° C. and a pressure of 6 kPa to obtain a light component II and a heavy component II.
[0081] S4: Cooling the light component II obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain anthracene.
[0082] S5: Cooling the heavy component II obtained in step S3 to 60° C. at a rate of 25° C. / h for crystallization, and then filtering, and drying the obtained filter cake to obtain amylanthracene.
[0083] Test Case The duration of stable operation of the system in each embodiment and comparative example (i.e., the duration from the start of operation to the occurrence of blockage) was recorded, and the yield and purity of anthracene and alkylanthracene were detected. The purity was determined by high performance liquid chromatography, and the yield was calculated as follows: (1) Calculation formula of anthracene yield: (2) Calculation formula for alkyl anthracene yield:
[0084] The test results are shown in Table 1.
[0085] Table 1 From Table 1 we can see that: (1) Compared with Comparative Example 1, the systems of Examples 1 to 5 can operate stably for a longer period of time, and the yield and purity of anthracene and alkyl anthracene are higher. The reason for this is that in Comparative Example 1, due to the characteristics of anthracene such as easy sublimation, high boiling point and melting point, it is impossible for it to maintain a stable fluid state. When it encounters a place where the temperature is lower than the distillation temperature, such as the pipe wall, it is easy to precipitate into a solid form, causing the pipe to be easily blocked. Compared with Comparative Example 1, an entrainer is added to Examples 1 to 5, and anthracene and alkyl anthracene are separated by azeotropic distillation. After the entrainer forms an azeotrope with anthracene, anthracene is not easy to sublime. The azeotrope can maintain a homogeneous fluid state in the pipe, thereby effectively alleviating the occurrence of pipe blockage, enabling the anthracene alkylation reaction product separation system to operate stably for a long time, and at the same time improving the yield and purity of anthracene and alkyl anthracene.
[0086] (2) Compared with Example 4, the purity and yield of anthracene in Examples 6 and 7 are higher. The reason is that: in Examples 6 and 7, glycerol and diethylene glycol are used as entrainers, and the glycerol tends to form an azeotrope with the reaction solvent in the anthracene alkylation reaction product and is separated in the distillation process of step S2, and the diethylene glycol tends to form an azeotrope with anthracene and is separated in the distillation process of step S3. Compared with the solution of using a single entrainer in Example 4, Examples 6 and 7 use the above two components in combination as entrainers, which can improve the selective separation effect of the reaction solvent and anthracene, thereby improving the purity and yield of the recovered anthracene.
[0087] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.
Claims
1. A method for separating anthracene alkylation reaction products, characterized in that: The following steps are involved: S1: pretreating the anthracene alkylation reaction product to remove part of the anthracene to obtain a pretreated product; S2: mixing the pretreated product and the entrainer, and performing distillation at 100-250° C. and 1-120 kPa to obtain a light component I and a heavy component I; the light component I comprises an azeotrope of the reaction solvent and the entrainer in the anthracene alkylation reaction product; S3: distilling the heavy component I at 100-300° C. and 0.5-100 kPa to obtain a light component II and a heavy component II; the light component II contains an azeotrope of anthracene and the entrainer; S4: Cooling and crystallizing the heavy component II, and performing solid-liquid separation to obtain alkyl anthracene.
2. The separation method according to claim 1, wherein After step S3, the light component II is cooled and crystallized, and solid-liquid separation is performed to obtain anthracene.
3. The separation method according to claim 1, characterized in that The specific process of step S1 includes: cooling and crystallizing the anthracene alkylation reaction product, removing the solid phase, and obtaining the liquid phase as the pretreatment product.
4. The separation method according to claim 3, characterized in that In step S1, the cooling crystallization process is carried out in the presence of seed crystals; the seed crystals are at least one of anthracene, ethylanthracene, butylanthracene and pentylanthracene, and the amount used is 0.2-2% of the mass of the anthracene alkylation reaction product; the terminal temperature of the cooling crystallization is 5-20°C.
5. The separation method according to claim 1, characterized in that The specific process of step S1 includes: performing vacuum distillation on the anthracene alkylation reaction product at 150-300° C. and 0.5-150 kPa, and obtaining a heavy fraction as a pretreatment product.
6. The separation method according to claim 1, characterized in that In step S2, the entrainer includes at least one of an alkane, an aromatic hydrocarbon, an alcohol, an ester and an ether, wherein the alkane is at least one of a C8-C18 straight-chain alkane and a branched-chain alkane, the aromatic hydrocarbon is at least one of benzene and an alkyl substituent of benzene in which the sum of the number of carbon atoms in all substituents is 2-10, the alcohol is at least one of methanol, ethanol, glycerol, diethylene glycol, triethylene glycol and tetraethylene glycol, the ester is at least one of methyl acetate, methyl benzoate, butyl acetate and phenyl acetate, and the ether is at least one of methyl ether, ethyl ether, dimethyl ether and sulfolane.
7. The separation method according to claim 6, wherein: In step S2, the entrainer is glycerol or diethylene glycol, the distillation temperature is 150-180°C, and the pressure is 30-55 kPa; in step S3, the distillation temperature is 166-178°C, and the pressure is 7-12 kPa; or, In step S2, the entrainer is glycerol and diethylene glycol in a mass ratio of 0.1-1:1, the distillation temperature is 150-180°C, and the pressure is 10-55kPa; in step S3, the distillation temperature is 165-180°C, and the pressure is 7-20kPa.
8. The separation method according to claim 1, 6 or 7, characterized in that: In step S2, the amount of the entrainer is 10-30 times the volume of the feed liquid.
9. The separation method according to claim 1, characterized in that The specific process of step S4 includes: The heavy component II is subjected to cooling crystallization at a cooling rate of 1-25°C / h and an end point temperature of 40-80°C, followed by solid-liquid separation to obtain alkyl anthracene; or, The heavy component II is subjected to cooling crystallization at a cooling rate of 20-100°C / h and an end point temperature of 40-80°C, followed by solid-liquid separation. The obtained solid component is washed with 40-80°C hot water to obtain alkyl anthracene.
10. The separation method according to claim 1, characterized in that In step S1, the reaction solvent in the anthracene alkylation reaction product is at least one of benzene and an alkylated substituent of benzene in which the sum of the carbon atoms in all substituents is 3-10; in step S4, the alkyl anthracene is at least one of ethyl anthracene, butyl anthracene, pentyl anthracene and hexyl anthracene.
Citation Information
Patent Citations
Separation method for mixture containing anthracene alkylation reaction products
CN109704910A