Method for simultaneously separating durene, prehnitene and pseudocumene from C10 aromatic hydrocarbons

Abstract

The present invention relates to the technical field of durene preparation, and discloses a method for simultaneously separating durene, prehnitene and pseudodurene from C10 aromatics. In this method, the C10 aromatics are distilled to remove heavy components, and after obtaining a durene mixture, atmospheric distillation is carried out to obtain a first durene-enriched liquid, a first prehnitene-enriched liquid and a first pseudodurene-enriched liquid; then the three durene-enriched liquids are respectively subjected to vacuum distillation to obtain a second durene-enriched liquid, a second prehnitene-enriched liquid and a second pseudodurene-enriched liquid; the second durene-enriched liquid is subjected to first cooling crystallization to obtain durene; the second pseudodurene-enriched liquid is subjected to second cooling crystallization to obtain pseudodurene; the second prehnitene-enriched liquid is contacted with a metal-organic framework material and then separated to obtain prehnitene. This method can not only separate the three durenes from C10 aromatics, but also take into account the purity and yield of the three durenes.

Description

Technical Field

[0001] The present invention relates to the technical field of durene preparation, and particularly to a method for simultaneously separating durene, prehnitene and pseudodurene from C10 aromatics. Background Art

[0002] Heavy aromatics are by-products in the processes of petroleum and coal processing, mainly C9 aromatics and C10 aromatics. Heavy aromatics mainly come from the catalytic reforming unit of refineries, the wide-cut catalytic reforming unit of polyester plants, ethylene plants and high-temperature coal coking plants. Among them, C10 aromatics mainly refer to the aromatic fractions containing ten carbon atoms obtained by catalytic reforming and ethylene production by cracking. The main components thereof include prehnitene, pseudodurene, durene, methylpropylbenzene, butylbenzene, diethylbenzene, methylindene, naphthalene, etc. In reformed aromatics, C10 aromatics account for about 5%, and among them, tetramethylbenzenes account for 2-3%; in pyrolysis gasoline heavy aromatics, C10 aromatics account for 10%, and among them, tetramethylbenzenes account for about 0.5%. There are dozens of components in the C10 aromatic fraction, and their boiling points are very close, making it difficult to separate them one by one. The existing technology generally directly makes petroleum resins from the mixed C9 and C10 aromatics or uses them as high-grade carbon and high-temperature solvents, etc.

[0003] The use value of C10 aromatics themselves is relatively low, but the added value of the tetramethylbenzenes (durene, prehnitene, pseudodurene) contained therein is relatively high. Among them, durene (1,2,4,5-tetramethylbenzene) is an important organic chemical raw material, mainly used for synthesizing pyromellitic dianhydride (referred to as PMDA for short) and preparing polyimide, epoxy resin curing agent and heat-resistant lubricating oil, etc. Prehnitene (1,2,3,4-tetramethylbenzene) can be used as the starting material for high-performance film materials such as polyimide and polyamide or the synthetic raw material for plasticizers of polymer materials. Pseudodurene (1,2,3,5-tetramethylbenzene) can be used as a fragrance additive and an intermediate for synthetic materials. With the continuous increase in the demand for polyimide, polymer materials and high-performance film materials, the markets for durene, prehnitene and pseudodurene are gradually expanding.

[0004] Among the tetramethylbenzenes, the preparation methods of durene are divided into two categories: one is the chemical synthesis method, including isomerization method, alkylation method and disproportionation reaction method, etc., but the chemical synthesis method has the disadvantages of complex process and high cost; the other is the separation and purification method, mainly separating and purifying durene with C10 aromatics as the raw material. Compared with the chemical synthesis method, this method can simplify the process, save energy consumption and reduce production costs at the same time. Prehnitene and pseudodurene are mainly prepared by synthesis, but due to the high preparation cost, there has been no industrial production so far.

[0005] Although there are many reports on the utilization of heavy aromatics at home and abroad, the utilization rate of C10 aromatics is still not high enough. Most of them are used as fuel, wasting the high-value tetramethylbenzene resources contained in C10 aromatics. Therefore, how to develop and utilize tetramethylbenzene in C10 aromatics is of great significance. In the prior art, there are many studies on the separation and purification of durene. Mainly, C10 aromatics (containing about 8-12% durene) are used as raw materials for the separation and purification of durene. The fraction with a boiling point of 190-200°C is cut by distillation. This fraction is a mixture of durene and its homologues, etc. The content of pseudocumene and vicinal tetramethylbenzene is relatively high, and their boiling points are close. It is impossible to separate them solely by distillation. Durene can be easily separated by methods such as crystallization, centrifugal separation, and pressing. However, the residual oil obtained after separation by this method still contains a large amount of durene and homologues. Some enterprises choose to repeat the above separation process for the residual oil again. Since the boiling points of homologues are very close to that of durene, it is very difficult to effectively separate and recycle the durene in the residual oil by using methods such as distillation, crystallization, centrifugal separation, and pressing again. Moreover, the repeated separation not only has a high production cost but also a low recovery rate. Another part of the enterprises, considering the processing economy, no longer separates and recycles the residual oil, but chooses to sell the residual oil directly as waste or directly mix it in the residual oil for sale, still unable to effectively utilize the high-value tetramethylbenzene resources in C10 aromatics. In order to improve the utilization rate of C10 aromatics, Li Huimin et al. (Isomerization of Pseudocumene to Durene in Liquid Phase [J]. Chemistry and Adhesion, 1992, 000(002): 72-76.) while concentrating, freezing, and separating and extracting durene from C10 aromatics, isomerize the pseudocumene therein to obtain durene.

[0006] However, in the prior art, there is no report on the method for simultaneously separating durene, vicinal tetramethylbenzene, and pseudocumene from C10 aromatics. Summary of the Invention

[0007] The object of the present invention is to overcome the problem in the prior art of how to develop and utilize the three tetramethylbenzenes in C10 aromatics, and to provide a method for simultaneously separating durene, vicinal tetramethylbenzene, and pseudocumene from C10 aromatics. This method can obtain durene with a purity of 92-98 wt%, pseudocumene with a purity of 75-78 wt%, and vicinal tetramethylbenzene with a purity of 82-85 wt%.

[0008] In order to achieve the above object, the present invention provides a method for simultaneously separating durene, vicinal tetramethylbenzene, and pseudocumene from C10 aromatics. The method includes the following steps:

[0009] (1) Distill C10 aromatics to remove heavy components to obtain a tetramethylbenzene mixture, and the boiling point of the tetramethylbenzene mixture is lower than 210°C;

[0010] (2) The pseudocumene mixture is subjected to atmospheric distillation to obtain a first mesitylene-enriched liquid, a first 1,2,4,5-tetramethylbenzene-enriched liquid, and a first pseudocumene-enriched liquid; wherein, the boiling range of the first mesitylene-enriched liquid is 195 - 198 °C, the boiling range of the first 1,2,4,5-tetramethylbenzene-enriched liquid is 199 - 202 °C, and the boiling range of the first pseudocumene-enriched liquid is 203 - 205 °C;

[0011] (3) The first mesitylene-enriched liquid, the first 1,2,4,5-tetramethylbenzene-enriched liquid, and the first pseudocumene-enriched liquid are respectively subjected to vacuum distillation to obtain a second mesitylene-enriched liquid, a second 1,2,4,5-tetramethylbenzene-enriched liquid, and a second pseudocumene-enriched liquid; wherein, the boiling range of the second mesitylene-enriched liquid is 100 - 104 °C, the boiling range of the second 1,2,4,5-tetramethylbenzene-enriched liquid is 105 - 110 °C, and the boiling range of the second pseudocumene-enriched liquid is 120 - 130 °C;

[0012] (4) The second mesitylene-enriched liquid is subjected to the first cooling crystallization to obtain mesitylene;

[0013] (5) The second pseudocumene-enriched liquid is subjected to the second cooling crystallization to obtain pseudocumene;

[0014] (6) The second 1,2,4,5-tetramethylbenzene-enriched liquid is contacted with a metal-organic framework material and then separated to obtain 1,2,4,5-tetramethylbenzene.

[0015] Through the above technical solution, when separating three kinds of tetramethylbenzenes from C10 aromatics by using the method provided by the present invention, the purity and yield of the three kinds of tetramethylbenzenes are taken into account simultaneously. By combining the processes of distillation, atmospheric distillation, and vacuum distillation under specific reaction conditions, three kinds of tetramethylbenzene-enriched liquids are obtained, and then they are respectively subjected to cooling crystallization or adsorbed and separated by using a specific adsorbent. While the energy consumption is relatively low, high-yield target products can be obtained, and the product purity is relatively high. Finally, mesitylene with a purity of 92 - 98 wt% and a yield of 65 - 75%, pseudocumene with a purity of 75 - 78 wt% and a yield of 18 - 23%, and 1,2,4,5-tetramethylbenzene with a purity of 82 - 85 wt% and a yield of 18 - 22% can be obtained. Description of the Drawings

[0016] Figure 1 is a schematic flow chart of the method provided by the present invention. Detailed Embodiments

[0017] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0018] In the present invention, without explicit specification, "first" and "second" do not represent the order of precedence, nor do they limit each material or operation. They are only used to distinguish each material or operation. For example, "first durene enrichment liquid" and "second durene enrichment liquid" are only used to distinguish to indicate that these are not the same durene enrichment liquid; "first cooling crystallization" and "second cooling crystallization" are only used to distinguish to indicate that these are not the same cooling crystallization. The same applies to the rest of the terms and will not be elaborated here.

[0019] The present invention provides a method for simultaneously separating durene, prehnitene, and pseudodurene from C10 aromatics. The method comprises the following steps:

[0020] (1) Distilling the C10 aromatics to remove heavy components to obtain a mixed xylene liquid, wherein the boiling point of the mixed xylene liquid is lower than 210 °C;

[0021] (2) Subjecting the mixed xylene liquid to atmospheric distillation to obtain a first durene enrichment liquid, a first prehnitene enrichment liquid, and a first pseudodurene enrichment liquid; wherein, the boiling range of the first durene enrichment liquid is 195 - 198 °C, the boiling range of the first prehnitene enrichment liquid is 199 - 202 °C, and the boiling range of the first pseudodurene enrichment liquid is 203 - 205 °C;

[0022] (3) Subjecting the first durene enrichment liquid, the first prehnitene enrichment liquid, and the first pseudodurene enrichment liquid to vacuum distillation respectively to obtain a second durene enrichment liquid, a second prehnitene enrichment liquid, and a second pseudodurene enrichment liquid; wherein, the boiling range of the second durene enrichment liquid is 100 - 104 °C, the boiling range of the second prehnitene enrichment liquid is 105 - 110 °C, and the boiling range of the second pseudodurene enrichment liquid is 120 - 130 °C;

[0023] (4) Subjecting the second durene enrichment liquid to a first cooling crystallization to obtain durene;

[0024] (5) Subjecting the second pseudodurene enrichment liquid to a second cooling crystallization to obtain pseudodurene;

[0025] (6) Contacting the second prehnitene enrichment liquid with a metal-organic framework material, and then separating to obtain prehnitene.

[0026] According to some embodiments of the present invention, preferably, in the C10 aromatics, the content of durene is 5 - 8 wt%, the content of prehnitene is 5 - 8 wt%, and the content of pseudodurene is 10 - 12 wt%.

[0027] According to some embodiments of the present invention, preferably, in step (1), the mixed xylene liquid is a fraction at 180 - 210 °C.

[0028] According to some embodiments of the present invention, preferably, in step (2), the conditions for atmospheric distillation include: the total reflux time is 0.5 - 24 hours, preferably 2 - 10 hours; the reflux ratio is 2 - 20:1, preferably 2 - 10:1; in this preferred case, both purity and energy consumption can be taken into account simultaneously.

[0029] According to some embodiments of the present invention, preferably, in the first mesitylene enriched liquid, the content of mesitylene is 20 - 30 wt%.

[0030] According to some embodiments of the present invention, preferably, in the first prehnitene enriched liquid, the content of prehnitene is 28 - 35 wt%.

[0031] According to some embodiments of the present invention, preferably, in the first pseudocumene enriched liquid, the content of pseudocumene is 35 - 42 wt%.

[0032] According to some embodiments of the present invention, preferably, in step (3), the conditions for vacuum distillation include: the pressure is 40 - 80 mmHg, preferably 50 - 70 mmHg; the total reflux time is 0.5 - 24 hours, preferably 3 - 9 hours; the reflux ratio is 2 - 20:1, preferably 8 - 20:1; in this preferred case, both purity and yield can be taken into account simultaneously.

[0033] According to some embodiments of the present invention, preferably, in the second mesitylene enriched liquid, the content of mesitylene is 28 - 32 wt%. In the method provided by the present invention, carried out under the above-defined conditions, the yield of the target product mesitylene can be 72 - 75%.

[0034] According to some embodiments of the present invention, preferably, in the second prehnitene enriched liquid, the content of prehnitene is 45 - 46 wt%. In the method provided by the present invention, carried out under the above-defined conditions, the yield of the target product prehnitene can be 19 - 22%.

[0035] According to some embodiments of the present invention, preferably, in the second pseudocumene enriched liquid, the content of pseudocumene is 49 - 52 wt%. In the method provided by the present invention, carried out under the above-defined conditions, the yield of the target product pseudocumene can be 20 - 23%.

[0036] According to some embodiments of the present invention, preferably, in step (4), the conditions for the first cooling crystallization include: a temperature of -35°C to 10°C and a time of 0.5 - 10 hours; more preferably, the conditions for the first cooling crystallization include: a temperature of -25°C to -15°C and a time of 2 - 10 hours. In this preferred case, both purity and yield can be taken into account simultaneously.

[0037] According to some embodiments of the present invention, preferably, in step (5), the conditions for the second cooling crystallization include: a temperature of -25°C to 10°C and a time of 0.5 - 10 hours; more preferably, the conditions for the second cooling crystallization include: a temperature of -10°C to 0°C and a time of 2 - 10 hours. In this preferred case, both purity and yield can be taken into account simultaneously.

[0038] According to some embodiments of the present invention, in step (6), a metal-organic framework material is used to separate and purify 1,2,4,5-tetramethylbenzene. Different from traditional zeolite and molecular sieve adsorbents, the metal-organic framework material has a high porosity and specific surface area, and can adsorb more tetramethylbenzene molecules, thereby achieving the purpose of purifying 1,2,4,5-tetramethylbenzene. The present invention has a wide selection range for the metal-organic framework material. Preferably, the metal-organic framework material is selected from at least one of MIL-101, MIL-53(Cu), NH 2 -UiO-66, Cu-BTC, ZIF-8, and MIL-53(Al). More preferably, the metal-organic framework material is selected from at least one of MIL-101, MIL-53(Cu), and MIL-53(Al). In this preferred case, the method can further improve the purity of 1,2,4,5-tetramethylbenzene.

[0039] According to some embodiments of the present invention, preferably, the metal-organic framework material is prepared by a solvothermal synthesis method and then washed with methanol to purify the material.

[0040] According to some embodiments of the present invention, in order to further improve the purity of 1,2,4,5-tetramethylbenzene, preferably, the mass ratio of the second 1,2,4,5-tetramethylbenzene enrichment liquid to the metal-organic framework material is 1:3 - 6.

[0041] According to some embodiments of the present invention, preferably, in step (6), the conditions for the contact include: a temperature of 25 - 35°C and a time of 6 - 24 hours.

[0042] According to some embodiments of the present invention, preferably, the purity of the durene simultaneously separated from the C10 aromatics by the method is 92 - 98 wt%, the purity of the 1,2,4,5-tetramethylbenzene is 82 - 85 wt%, and the purity of the pseudocumene is 75 - 78 wt%.

[0043] According to some embodiments of the present invention, preferably, the yield of durene simultaneously separated from C10 aromatics by using the method is 65 - 75%, the yield of prehnitene is 18 - 22%, and the yield of pseudocumene is 18 - 23%.

[0044] According to some embodiments of the present invention, in the C10 aromatics, each enriched liquid, and the product, the contents of durene, prehnitene, and pseudocumene are measured by gas chromatography - mass spectrometry.

[0045] Figure 1 FIG. is a schematic flow chart of the method provided by the present invention. The raw material C10 aromatics are distilled to remove heavy components to obtain a mixed xylene liquid; the mixed xylene liquid is subjected to atmospheric distillation to obtain a first durene - enriched liquid, a first prehnitene - enriched liquid, and a first pseudocumene - enriched liquid; the first durene - enriched liquid, the first prehnitene - enriched liquid, and the first pseudocumene - enriched liquid are respectively subjected to vacuum distillation to obtain a second durene - enriched liquid, a second prehnitene - enriched liquid, and a second pseudocumene - enriched liquid;

[0046] The second durene - enriched liquid is subjected to a first cooling crystallization to obtain durene;

[0047] The second pseudocumene - enriched liquid is subjected to a second cooling crystallization to obtain pseudocumene;

[0048] The second prehnitene - enriched liquid is contacted with a metal - organic framework material and then separated (i.e., adsorption separation) to obtain prehnitene.

[0049] The present invention will be described in detail below through examples.

[0050] In the following examples and comparative examples, the raw material is C10 aromatics provided by the Zhenhai Refining & Chemical catalytic reforming unit. This C10 aromatics contains 7 wt% of durene, 7 wt% of prehnitene, 11 wt% of pseudocumene, 18% of naphthalene, and 4% of 1 - methyl - 3 - n - propylbenzene.

[0051] Examples 1 - 3 are used to illustrate the method for simultaneously separating durene, prehnitene, and pseudocumene from C10 aromatics.

[0052] Example 1

[0053] (1) Take 500 mL of C10 aromatics and place them in the still pot of the distillation device. Turn on the heating device and intercept the fraction at 180 - 210 °C to obtain a mixed xylene liquid, and the boiling point of this mixed xylene liquid is lower than 210 °C;

[0054] (2) The tetramethylbenzene mixture is fed into an atmospheric distillation unit for atmospheric distillation. The total reflux time is 2 hours, the reflux ratio is 10:1, to obtain a first mesitylene-rich liquid with a boiling range of 195 - 198 °C, a first 1,2,3,4-tetramethylbenzene-rich liquid with a boiling range of 199 - 202 °C, and a first pseudocumene-rich liquid with a boiling range of 203 - 205 °C;

[0055] Among them, the content of mesitylene in the first mesitylene-rich liquid is 20 wt%, the content of 1,2,3,4-tetramethylbenzene in the first 1,2,3,4-tetramethylbenzene-rich liquid is 28 wt%, and the content of pseudocumene in the first pseudocumene-rich liquid is 35 wt%;

[0056] (3) The first mesitylene-rich liquid, the first 1,2,3,4-tetramethylbenzene-rich liquid, and the first pseudocumene-rich liquid are respectively fed into a vacuum distillation unit for vacuum distillation. The pressure is 40 mmHg, the total reflux time is 3 hours, the reflux ratio is 8:1, to obtain a second mesitylene-rich liquid with a boiling range of 100 - 104 °C, a second 1,2,3,4-tetramethylbenzene-rich liquid with a boiling range of 105 - 110 °C, and a second pseudocumene-rich liquid with a boiling range of 120 - 130 °C;

[0057] Among them, the content of mesitylene in the second mesitylene-rich liquid is 28 wt%, the yield is 75%, the content of 1,2,3,4-tetramethylbenzene in the second 1,2,3,4-tetramethylbenzene-rich liquid is 45 wt%, the yield is 22%, the content of pseudocumene in the second pseudocumene-rich liquid is 49 wt%, and the yield is 23%;

[0058] (4) The second mesitylene-rich liquid is fed into a crystallizer. The cooling circulating water is turned on, and crystallization is carried out for 2 hours under the conditions of a stirring speed of 150 rpm and a temperature of -25 °C, and then suction filtration is carried out for 30 minutes to obtain mesitylene with a purity of 95 wt% and a yield of 65%;

[0059] (5) The second pseudocumene-rich liquid is fed into a crystallizer. The cooling circulating water is turned on, and crystallization is carried out for 2 hours under the conditions of a stirring speed of 150 rpm and a temperature of -10 °C, and then suction filtration is carried out for 30 minutes to obtain pseudocumene with a purity of 76 wt% and a yield of 20%;

[0060] (6) 5 g of the metal-organic framework material MIL-101 is put into 5 mL of the second 1,2,3,4-tetramethylbenzene-rich liquid, and after adsorption at 35 °C for 8 hours, the supernatant is separated to obtain 1,2,3,4-tetramethylbenzene with a purity of 82 wt% and a yield of 18%.

[0061] Example 2

[0062] (1) Take 500 mL of C10 aromatics and place them in the distillation unit kettle. Turn on the heating device and intercept the fraction with a boiling range of 180 - 210 °C to obtain a tetramethylbenzene mixture, and the boiling point of this tetramethylbenzene mixture is lower than 210 °C;

[0063] (2) The tetramethylbenzene mixture is introduced into an atmospheric distillation unit for atmospheric distillation. The total reflux time is 6 hours, the reflux ratio is 10:1, and a first mesitylene-rich liquid with a boiling range of 195 - 198 °C, a first pseudocumene-rich liquid with a boiling range of 199 - 202 °C, and a first prehnitene-rich liquid with a boiling range of 203 - 205 °C are obtained;

[0064] Among them, the content of mesitylene in the first mesitylene-rich liquid is 28 wt%, the content of pseudocumene in the first pseudocumene-rich liquid is 32 wt%, and the content of prehnitene in the first prehnitene-rich liquid is 40 wt%;

[0065] (3) The first mesitylene-rich liquid, the first pseudocumene-rich liquid, and the first prehnitene-rich liquid are respectively introduced into a vacuum distillation unit for vacuum distillation. The pressure is 80 mmHg, the total reflux time is 6 hours, the reflux ratio is 8:1, and a second mesitylene-rich liquid with a boiling range of 100 - 104 °C, a second pseudocumene-rich liquid with a boiling range of 105 - 110 °C, and a second prehnitene-rich liquid with a boiling range of 120 - 130 °C are obtained;

[0066] Among them, the content of mesitylene in the second mesitylene-rich liquid is 30 wt%, the yield is 72%, the content of pseudocumene in the second pseudocumene-rich liquid is 46 wt%, the yield is 20%, the content of prehnitene in the second prehnitene-rich liquid is 51 wt%, and the yield is 21%;

[0067] (4) The second mesitylene-rich liquid is introduced into a crystallizer. The cooling circulating water is turned on, and crystallization is carried out for 2 hours under the conditions of a stirring speed of 150 rpm and a temperature of -20 °C, and then suction filtration is carried out for 30 minutes to obtain mesitylene with a purity of 94 wt% and a yield of 70%;

[0068] (5) The second prehnitene-rich liquid is introduced into a crystallizer. The cooling circulating water is turned on, and crystallization is carried out for 2 hours under the conditions of a stirring speed of 150 rpm and a temperature of -5 °C, and then suction filtration is carried out for 30 minutes to obtain prehnitene with a purity of 75 wt% and a yield of 21%;

[0069] (6) 5 g of the metal-organic framework material MIL-53(Cu) is put into 5 mL of the second pseudocumene-rich liquid. After adsorption at 25 °C for 8 hours, the upper clear liquid is separated to obtain pseudocumene with a purity of 83 wt% and a yield of 20%.

[0070] Example 3

[0071] (1) 500 mL of C10 aromatics is placed in the still pot of a distillation device. The heating device is turned on, and the fraction with a boiling range of 180 - 210 °C is intercepted to obtain a tetramethylbenzene mixture, and the boiling point of this tetramethylbenzene mixture is lower than 210 °C;

[0072] (2) The pseudocumene mixture is introduced into an atmospheric distillation unit for atmospheric distillation. The total reflux time is 10 hours, the reflux ratio is 10:1, and a first pseudocumene enriched liquid with a boiling range of 195 - 198 °C, a first durene enriched liquid with a boiling range of 199 - 202 °C, and a first prehnitene enriched liquid with a boiling range of 203 - 205 °C are obtained;

[0073] Among them, the content of pseudocumene in the first pseudocumene enriched liquid is 30 wt%, the content of durene in the first durene enriched liquid is 35 wt%, and the content of prehnitene in the first prehnitene enriched liquid is 42 wt%;

[0074] (3) The first pseudocumene enriched liquid, the first durene enriched liquid, and the first prehnitene enriched liquid are respectively introduced into a vacuum distillation unit for vacuum distillation. The pressure is 60 mmHg, the total reflux time is 9 hours, the reflux ratio is 8:1, and a second pseudocumene enriched liquid with a boiling range of 100 - 104 °C, a second durene enriched liquid with a boiling range of 105 - 110 °C, and a second prehnitene enriched liquid with a boiling range of 120 - 130 °C are obtained;

[0075] Among them, the content of pseudocumene in the second pseudocumene enriched liquid is 32 wt%, the yield is 73%, the content of durene in the second durene enriched liquid is 48 wt%, the yield is 19%, the content of prehnitene in the second prehnitene enriched liquid is 52 wt%, and the yield is 23%;

[0076] (4) The second pseudocumene enriched liquid is introduced into a crystallizer. The cooling circulating water is turned on, and crystallization is carried out for 2 hours under the conditions of a stirring speed of 150 rpm and a temperature of -15 °C, and then suction filtration is carried out for 30 minutes to obtain pseudocumene with a purity of 96 wt% and a yield of 68%;

[0077] (5) The second prehnitene enriched liquid is introduced into a crystallizer. The cooling circulating water is turned on, and crystallization is carried out for 2 hours under the conditions of a stirring speed of 150 rpm and a temperature of 0 °C, and then suction filtration is carried out for 30 minutes to obtain prehnitene with a purity of 78 wt% and a yield of 18%;

[0078] (6) 5 g of the metal-organic framework material MIL-53(Al) is put into 5 mL of the second durene enriched liquid, and after reacting at 15 °C for 8 hours, the supernatant is separated to obtain durene with a purity of 85 wt% and a yield of 19%.

[0079] As Figure 1 shown, the raw material C10 aromatics are distilled to remove heavy components to obtain a pseudocumene mixture, and the boiling point of the pseudocumene mixture is lower than 210 °C;

[0080] The mixed solution of tetramethylbenzenes is subjected to atmospheric distillation to obtain a first mesitylene-enriched liquid, a first pyromellitic acid-enriched liquid, and a first pseudocumene-enriched liquid. Among them, the boiling range of the first mesitylene-enriched liquid is 195 - 198 °C, the boiling range of the first pyromellitic acid-enriched liquid is 199 - 202 °C, and the boiling range of the first pseudocumene-enriched liquid is 203 - 205 °C;

[0081] The first mesitylene-enriched liquid, the first pyromellitic acid-enriched liquid, and the first pseudocumene-enriched liquid are respectively subjected to vacuum distillation to obtain a second mesitylene-enriched liquid, a second pyromellitic acid-enriched liquid, and a second pseudocumene-enriched liquid. Among them, the boiling range of the second mesitylene-enriched liquid is 100 - 104 °C, the boiling range of the second pyromellitic acid-enriched liquid is 105 - 110 °C, and the boiling range of the second pseudocumene-enriched liquid is 120 - 130 °C;

[0082] The second mesitylene-enriched liquid is subjected to the first cooling crystallization to obtain mesitylene, with a purity of 92 - 98 wt% and a yield of 65 - 70%;

[0083] The second pseudocumene-enriched liquid is subjected to the second cooling crystallization to obtain pseudocumene, with a purity of 75 - 78 wt% and a yield of 18 - 20%;

[0084] The second pyromellitic acid-enriched liquid is contacted with a metal-organic framework material and then separated (i.e., adsorption separation) to obtain pyromellitic acid, with a purity of 82 - 85 wt% and a yield of 18 - 21%.

[0085] From the above results, it can be seen that by using the method provided by the present invention to separate three kinds of tetramethylbenzenes from C10 aromatics, high-yield target products can be obtained, and the product purities are all relatively high. Mesitylene with a purity of 92 - 98 wt% and a yield of 65 - 75%, pseudocumene with a purity of 65 - 75 wt% and a yield of 18 - 23%, and pyromellitic acid with a purity of 82 - 85 wt% and a yield of 18 - 22% can be obtained.

[0086] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for simultaneously separating durene, prehnitene, and pseudodurene from C10 aromatics, characterized in that, the method comprises the following steps: (1) Distilling C10 aromatics to remove heavy components to obtain a mixed xylene solution, and the boiling point of the mixed xylene solution is lower than 210 °C; (2) Subjecting the mixed xylene solution to atmospheric distillation to obtain a first durene-enriched solution, a first prehnitene-enriched solution, and a first pseudodurene-enriched solution; wherein, the boiling range of the first durene-enriched solution is 195-198 °C, the boiling range of the first prehnitene-enriched solution is 199-202 °C, and the boiling range of the first pseudodurene-enriched solution is 203-205 °C; (3) Subjecting the first durene-enriched solution, the first prehnitene-enriched solution, and the first pseudodurene-enriched solution to vacuum distillation respectively to obtain a second durene-enriched solution, a second prehnitene-enriched solution, and a second pseudodurene-enriched solution; wherein, the boiling range of the second durene-enriched solution is 100-104 °C, the boiling range of the second prehnitene-enriched solution is 105-110 °C, and the boiling range of the second pseudodurene-enriched solution is 120-130 °C; (4) Subjecting the second durene-enriched solution to the first cooling crystallization to obtain durene; (5) Subjecting the second pseudodurene-enriched solution to the second cooling crystallization to obtain pseudodurene; (6) Contacting the second prehnitene-enriched solution with a metal-organic framework material, and then separating to obtain prehnitene; wherein, in step (2), the conditions of the atmospheric distillation include: the reflux ratio is 10-20:1; wherein, in step (3), the conditions of the vacuum distillation include: the pressure is 40-80 mmHg; the reflux ratio is 8-20:1; wherein, in step (4), the conditions of the first cooling crystallization include: the temperature is -25 °C to -15 °C; wherein, in step (5), the conditions of the second cooling crystallization include: the temperature is -10 °C to 0 °C.

2. The method according to claim 1, wherein, in the C10 aromatics, the content of durene is 5-8 wt%, the content of prehnitene is 5-8 wt%, and the content of pseudodurene is 10-12 wt%.

3. The method according to claim 1 or 2, wherein, in step (1), the mixed xylene solution is a fraction at 180-210 °C.

4. The method according to claim 1 or 2, wherein, in step (2), the conditions of the atmospheric distillation include: the time of total reflux is 0.5-24 hours.

5. The method according to claim 4, wherein, in step (2), the conditions of the atmospheric distillation include: the time of total reflux is 2-10 hours.

6. The method according to claim 1 or 2, wherein, in the first durene-enriched solution, the content of durene is 20-30 wt%.

7. The method according to claim 1 or 2, wherein, in the first prehnitene-enriched solution, the content of prehnitene is 28-35 wt%.

8. The method according to claim 1 or 2, wherein, in the first pseudodurene-enriched solution, the content of pseudodurene is 35-42 wt%.

9. The method according to claim 1 or 2, Among them, In step (3), the conditions for vacuum distillation include: the time of total reflux is 0.5 - 24 hours.

10. The method according to claim 9, Among them, In step (3), the conditions for vacuum distillation include: the time of total reflux is 3 - 9 hours.

11. The method according to claim 1 or 2, Among them, In step (3), the conditions for vacuum distillation include: the pressure is 50 - 70 mmHg.

12. The method according to claim 1 or 2, Among them, In the second mesitylene enriched liquid, the content of mesitylene is 28 - 32 wt%.

13. The method according to claim 1 or 2, Among them, In the second durene enriched liquid, the content of durene is 45 - 46 wt%.

14. The method according to claim 1 or 2, Among them, In the second pseudocumene enriched liquid, the content of pseudocumene is 49 - 52 wt%.

15. The method according to claim 1 or 2, Among them, In step (4), the conditions for the first cooling crystallization include: the time is 0.5 - 10 hours.

16. The method according to claim 15, Among them, In step (4), the conditions for the first cooling crystallization include: the time is 2 - 10 hours.

17. The method according to claim 1 or 2, Among them, In step (5), the conditions for the second cooling crystallization include: the time is 0.5 - 10 hours.

18. The method according to claim 17, Among them, In step (5), the conditions for the second cooling crystallization include: the time is 2 - 10 hours.

19. The method according to claim 1 or 2, Among them, In step (6), the metal-organic framework material is selected from at least one of MIL-101, MIL-53-Cu, NH 2 -UiO-66, Cu-BTC, ZIF-8, and MIL-53-Al.

20. The method according to claim 19, Among them, In step (6), the metal-organic framework material is selected from at least one of MIL-101, MIL-53-Cu, and MIL-53-Al.

21. The method according to claim 1 or 2, Among them, The mass ratio of the second durene enriched liquid to the metal-organic framework material is 1:3 - 6.

22. The method according to claim 1 or 2, Among them, In step (6), the conditions for the contact include: the temperature is 25 - 35 °C, and the time is 6 - 24 hours.

23. The method according to claim 1 or 2, Among them, The purity of mesitylene is 92 - 98 wt%, the purity of durene is 82 - 85 wt%, and the purity of pseudocumene is 75 - 78 wt%.

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