Process and apparatus for producing mesitylene

Abstract

The present application relates to C9 and above heavy aromatic hydrocarbon processing technical field, it is a kind of production mesitylene method and device, the former is carried out according to the following method: under catalyst, C9 and above heavy aromatic hydrocarbon and hydrogen are carried out dealkylation isomerization reaction, then liquid phase product is separated by dehydrogenation, after three-stage rectification, mesitylene is obtained.The present application uses C9 and above heavy aromatic hydrocarbon to carry out dealkylation isomerization process, eliminates the interference of methyl ethyl benzene to mesitylene separation, maximizes the production of mesitylene, methyl ethyl benzene content <0.5%, the yield of mesitylene is greater than 25%, its process is simple, the yield of mesitylene is high, the production cost is low, compared with the traditional production BTX or blending gasoline route, the method for producing mesitylene of the present application realizes the maximization of C9 and above heavy aromatic hydrocarbon resources.

Description

Technical Field

[0001] This invention relates to the field of C9 and above heavy aromatic hydrocarbon processing technology, and is a method and apparatus for producing mesitylene. Background Technology

[0002] Since there are nine isomers of C9 and above heavy aromatic hydrocarbons, after separation, the industrially available products include mesitylene, pseudotrimethylbenzene, m-methylethylbenzene, and p-methylethylbenzene, among which mesitylene has the highest added value. Mesitylene (1,3,5-trimethylbenzene) is an important chemical raw material, and based on it, various dye intermediates and important fine chemical products such as pyromellitic anhydride, mesityleneamine, pyromellitic acid, and terpene alcohols can be produced.

[0003] The main industrial production methods for mesitylene are synthesis and separation and purification. The synthesis method uses pseudotrimethylbenzene as raw material (pseudotrimethylbenzene raw material is mostly separated from reformed or cracked C9 aromatics) to generate mesitylene by isomerization. The separation and purification method uses C9 mixed aromatics by-products from catalytic reforming units, paraxylene units, etc. as raw materials to directly separate and extract mesitylene.

[0004] From the perspective of existing technologies, the difficulty in producing and separating mesitylene lies in the presence of C9 aromatic isomers such as ethylbenzene and propene in the raw materials. These isomers have boiling points very close to that of mesitylene. The boiling points of mesitylene are also very close to those of p-ethylbenzene, m-ethylbenzene, and o-ethylbenzene, especially o-ethylbenzene, whose boiling point differs from that of mesitylene by only 0.3°C. Industrially, distillation is not feasible, and the industrial production of mesitylene is mainly affected by the interference of ethylbenzene. Therefore, simple separation and purification is extremely difficult and costly. Alkylation, isomerization, and other methods can be used to utilize the structural differences between ethylbenzene and mesitylene, and the components can be separated through chemical reactions.

[0005] Chinese patent document CN103772121A discloses a method for cracking C9 and above heavy aromatic hydrocarbons to produce more tricresylene. This method involves hydrogenating and dealkylating C9 and above heavy aromatic hydrocarbons and subjecting them to alkyl transfer with light aromatic hydrocarbons, thereby enriching the tricresylene in the C9 aromatic hydrocarbons. Light hydrocarbons, BTX, mesitylene, and pseudotrimethylbenzene fractions, as well as C9 aromatic hydrocarbons and trimethylbenzene fractions, are separated. While this method cracks non-aromatic and heavy aromatic hydrocarbons, reducing the difficulty of separation, it fails to produce mesitylene. Furthermore, the yields of light hydrocarbons and BTX are relatively high, while the yield of tricresylene is low, indicating that the product's value needs further improvement.

[0006] Chinese patent document CN1139095A discloses a method for separating and preparing mesitylene from C9 mixed aromatics. The method involves first distilling a C9 mixed aromatic feedstock containing more than 22% methyl ethyl benzoate (MEBenz) through primary distillation. Then, a mixed fraction containing MEBenz, pseudotrimethylbenzene, and ortho-, meta-, and para-MEBenz is used as the reaction feedstock. Tert-butanol, concentrated sulfuric acid, aluminum trichloride, and hydrochloric acid are added, followed by alkylation and sedimentation to convert MEBenz into high-boiling-point compounds. Further distillation separation yields a MEBenz product with a purity greater than 98%. However, this method, while converting MEBenz, also converts a large amount of pseudotrimethylbenzene into alkyl aromatics with more carbon atoms, resulting in a loss of MEBenz. Furthermore, this method causes severe corrosion to equipment, making it difficult to apply industrially.

[0007] Chinese patent document CN1313269A discloses a process for separating high-purity pseudotrimethylbenzene from reformed heavy aromatics. The process involves continuously distilling heavy aromatics from a refinery reforming unit through two packed towers to separate a high-purity pseudotrimethylbenzene fraction, but it does not yield high-purity mesitylene.

[0008] Chinese patent document CN1974500A discloses a trimethylbenzene serial separation device and method, which uses a three-tower serial process to separate reformed heavy aromatics, and can produce high-purity pseudotrimethylbenzene and co-produce enriched mesitylene with a purity of more than 35%, although the mesitylene has a low purity.

[0009] Among the existing technologies mentioned above, the process for separating and producing mesitylene is relatively long and complex, and the yield of mesitylene is low, the production cost is high, and the industrial application is difficult. Summary of the Invention

[0010] This invention provides a method and apparatus for producing mesitylene, which overcomes the shortcomings of the prior art and effectively solves the problems of long process, complex process and low yield of existing mesitylene production methods.

[0011] One of the technical solutions of the present invention is achieved through the following measures: a method for producing mesitylene, carried out according to the following method:

[0012] S1, C9 and above heavy aromatics are mixed with hydrogen and sent to a dealkylation isomerization reactor filled with catalyst to react and obtain reaction products;

[0013] S2, the reaction product is sent to a high-pressure separator for dehydrogenation separation to obtain hydrogen and liquid products, and the hydrogen is recycled;

[0014] S3, the liquid product is sent to the BTX column for separation to obtain BTX product and C9 and above component products. The C9 and above component products are sent from the bottom of the column to the mesitylene column for separation to obtain mesitylene product and C9 and above component products after removing mesitylene.

[0015] S4, the C9 and above components of the product after removing mesitylene are sent from the bottom of the tower to the terephthalene and terephthalene tower for further separation to obtain a mixture of C10 and above heavy aromatics, terephthalene and terephthalene.

[0016] S5, the mixture of pseudotrimethylbenzene and terephthalene is returned from the top of the column to the dealkylation isomerization reactor for reaction, whereby the mixture of pseudotrimethylbenzene and terephthalene is converted into mesitylene.

[0017] The following are further optimizations and / or improvements to one of the above-mentioned inventive technical solutions:

[0018] In step S1 above, the mass hourly space velocity (WHSV) of C9 and above heavy aromatics is 1 h⁻¹. -1 up to 6h -1 The molar ratio of hydrogen to C9 and above heavy aromatics is 2 to 4:1.

[0019] In step S1 above, the reaction temperature is 300℃ to 420℃ and the reaction pressure is 0.5MPa to 3.0MPa.

[0020] The operating temperature of the BTX tower is 162℃ to 164℃, the operating temperature of the mesitylene tower is 165℃ to 167℃, and the operating temperature of the cycloxylene and cycloxylene tower is 177℃ to 179℃.

[0021] The catalysts mentioned above are molecular sieve catalysts supported with 0.1 wt% to 5 wt% metal. The molecular sieve support is NKF-5 type molecular sieve, and the metal is one or more of Co, Ni and Mo.

[0022] The catalyst was obtained by impregnating a molecular sieve support with a metal-containing impregnation solution using an equal-volume impregnation method, followed by drying and calcination.

[0023] The aforementioned dealkylation isomerization reactor is a fixed-bed reactor.

[0024] One of the technical solutions of this invention is achieved through the following measures: an apparatus for implementing a method for producing mesitylene, comprising a dealkylation isomerization reactor, a high-pressure separator, a BTX tower, a mesitylene tower, and a meta- and terephthalene tower; the top inlet of the dealkylation isomerization reactor is fixedly connected to a feed pipeline of C10 and above heavy aromatics; a hydrogen pipeline is fixedly connected to the feed pipeline of C10 and above heavy aromatics; a first processing pipeline is fixedly connected between the bottom outlet of the dealkylation isomerization reactor and the side inlet of the high-pressure separator; a second processing pipeline is fixedly connected between the bottom outlet of the high-pressure separator and the side inlet of the BTX tower; and a third processing pipeline is fixedly connected between the top outlet of the high-pressure separator and the feed pipeline of C10 and above heavy aromatics. A hydrogen recycling pipeline is fixedly connected between the above heavy aromatics feed pipelines. A third processing pipeline is fixedly connected between the bottom outlet of the BTX tower and the side inlet of the mesitylene tower. A BTX product conveying pipeline is fixedly connected to the top outlet of the BTX tower. A fourth processing pipeline is fixedly connected between the bottom outlet of the mesitylene tower and the side inlet of the methyltrimethylbenzene and methyltrimethylbenzene towers. A mesitylene product conveying pipeline is fixedly connected to the top outlet of the methyltrimethylbenzene and methyltrimethylbenzene towers. A mixture conveying pipeline of methyltrimethylbenzene and methyltrimethylbenzene is fixedly connected between the top outlet of the methyltrimethylbenzene and methyltrimethylbenzene towers and the feed pipeline of C10 and above heavy aromatics. A C10 and above heavy aromatics conveying pipeline is fixedly connected to the bottom outlet of the methyltrimethylbenzene and methyltrimethylbenzene towers.

[0025] This invention employs a dealkylation isomerization process using C9 and higher heavy aromatics, eliminating the interference of ethylbenzene on the separation of mesitylene and maximizing the production of mesitylene. The ethylbenzene content is <0.5%, and the mesitylene yield is greater than 25%. The process is simple, has a high mesitylene yield, and low production cost. Compared with traditional routes for producing BTX or blended gasoline, this invention's method for producing mesitylene maximizes the utilization of C9 and higher heavy aromatic resources. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the process flow of Embodiment 15 of the present invention.

[0027] The codes in the attached diagram are as follows: 1 is the dealkylation isomerization reactor, 2 is the high-pressure separator, 3 is the BTX tower, 4 is the mesitylene tower, 5 is the pseudotrimethylbenzene and teremethylbenzene tower, 6 is the feed pipeline for C9 and above heavy aromatics, 7 is the hydrogen pipeline, 8 is the first processing pipeline, 9 is the second processing pipeline, 10 is the hydrogen recycling pipeline, 11 is the third processing pipeline, 12 is the BTX product conveying pipeline, 13 is the fourth processing pipeline, 14 is the mesitylene product conveying pipeline, 15 is the C10 and above heavy aromatics conveying pipeline, and 16 is the conveying pipeline for a mixture of pseudotrimethylbenzene and teremethylbenzene. Detailed Implementation

[0028] This invention is not limited to the following embodiments; specific implementation methods can be determined according to the technical solution of this invention and actual conditions. Unless otherwise specified, all chemical reagents and chemical products mentioned in this invention are well-known and commonly used chemical reagents and chemical products in the prior art; unless otherwise specified, all percentages in this invention are mass percentages.

[0029] The present invention will be further described below with reference to embodiments:

[0030] Example 1: As Figure 1 As shown, the method for producing mesitylene is carried out according to the following procedure:

[0031] S1, C9 and above heavy aromatics are mixed with hydrogen and sent to dealkylation isomerization reactor 1 filled with catalyst to react and obtain reaction products;

[0032] S2, the reaction product is sent to high-pressure separator 2 for dehydrogenation separation to obtain hydrogen and liquid products, and the hydrogen is recycled;

[0033] S3, the liquid product is sent to BTX column 3 for separation to obtain BTX product and C9 and above component products. The C9 and above component products are sent from the bottom of the column to mesitylene column 4 for separation to obtain mesitylene product and C9 and above component products after removing mesitylene.

[0034] S4, the C9 and above components of the product after removing mesitylene are sent from the bottom of the tower to the terephthalene and terephthalene tower 5 for further separation to obtain a mixture of C10 and above heavy aromatics, terephthalene and terephthalene.

[0035] S5, the mixture of pseudotrimethylbenzene and terephthalene is returned from the top of the column to the dealkylation isomerization reactor 1 for reaction, and the mixture of pseudotrimethylbenzene and terephthalene is converted into mesitylene.

[0036] In this invention, the reaction product obtained in step S1 contains less than 31% BTX, more than 55% trimethylbenzene, no propylbenzene, less than 0.5% methyl ethylbenzene, and a yield of more than 25% mesitylene.

[0037] Example 2: As an optimization of the above example, in step S1, the mass hourly space velocity (MSV) of C9 and above heavy aromatics is 1 h⁻¹. -1 up to 6h -1 The molar ratio of hydrogen to C9 and above heavy aromatics is 2 to 4:1.

[0038] Example 3: As an optimization of the above example, in step S1, the reaction temperature is 300°C to 420°C and the reaction pressure is 0.5MPa to 3.0MPa.

[0039] Example 4: As an optimization of the above example, the operating temperature of BTX tower 3 is 162°C to 164°C, the operating temperature of mesitylene tower 4 is 165°C to 167°C, and the operating temperature of cyclohexylene and cyclohexylene tower 5 is 177°C to 179°C.

[0040] Example 5: As an optimization of the above examples, the catalyst is a molecular sieve catalyst supported with 0.1 wt% to 5 wt% metal, the molecular sieve support is NKF-5 type molecular sieve, and the metal is one or more of Co, Ni and Mo.

[0041] Example 6: As an optimization of the above examples, the catalyst was obtained by the following method: the molecular sieve support was impregnated with a metal-containing impregnation solution by an equal volume impregnation method, and then dried and calcined.

[0042] Example 7: As an optimization of the above example, the dealkylation isomerization reactor 1 is a fixed-bed reactor.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] Firstly, by using C9 and above heavy aromatics as raw materials and through dealkylation isomerization reaction, the content of methyl ethylbenzene can be significantly reduced, the interference of methyl ethylbenzene on the separation of mesitylene can be eliminated, and as much mesitylene as possible can be retained. Furthermore, the composition of mesitylene can be brought to near equilibrium, which greatly reduces the process and cost of producing mesitylene from traditional C9 and above heavy aromatics and significantly improves the yield of mesitylene.

[0045] Secondly, the dealkylation isomerization reaction conditions are mild, with few side reactions, low hydrogen consumption, very low dry gas and LPG (liquefied petroleum gas) content in the product, low BTX (benzene-toluene-xylene mixture) content, small loss of trimethylbenzene, high yield of mesitylene, enrichment of mesitylene concentration in C10 and above heavy aromatics, and excellent distribution of dealkylation reaction products.

[0046] Third, the separated BTX product can be further utilized, and the concentration of mesitylene in C10 and above heavy aromatics is also increased, which facilitates the subsequent separation of mesitylene.

[0047] In summary, compared to traditional routes for producing BTX or blended gasoline, the method for producing mesitylene of this invention maximizes the utilization of C9 and higher heavy aromatic hydrocarbon resources.

[0048] Example 8:

[0049] The method for producing mesitylene is carried out as follows:

[0050] S1, C9 and higher heavy aromatics generated by the catalytic reloading unit are mixed with hydrogen and then fed into a dealkylation isomerization reactor 1 packed with a catalyst (NKF-5 molecular sieve loaded with 5 wt% Ni) for reaction. The reaction temperature in the dealkylation isomerization reactor 1 is controlled at 310℃ to 320℃, the reaction pressure at 1.0 MPa, and the feed mass hourly space velocity at 2.0 h⁻¹. -1 The molar ratio of hydrogen to C9 and above heavy aromatic hydrocarbons is 4:1, and the reaction product is obtained.

[0051] S2, the reaction product is sent to the high-pressure separator 2 for dehydrogenation separation to obtain hydrogen and liquid products. The hydrogen is returned to the dealkylation isomerization reactor 1 for recycling.

[0052] S3, the liquid product is sent to BTX column 3 for separation. The operating temperature of BTX column 3 is controlled at 162℃ to 164℃. The BTX product with a boiling point lower than 164℃ is sent out from the top of the column. The C9 and above components with a boiling point higher than 164℃ are sent from the bottom of the column to mesitylene column 4 for separation. The operating temperature of mesitylene column 4 is controlled at 165℃ to 167℃. The mesitylene product with a boiling point lower than 167℃ is sent out from the top of the column.

[0053] S4, the C9 and above components with boiling points higher than 167℃ after removing mesitylene are sent from the bottom of the column to the terephthalene column 5 for further separation. The operating temperature of the terephthalene column 5 is controlled at 177℃ to 179℃, and the C10 and above heavy aromatics with boiling points higher than 179℃ are sent out from the bottom of the column.

[0054] S5, the mixture of pseudotrimethylbenzene and terephthalene with a boiling point of less than 179℃ is sent out from the top of the column and returned to the dealkylation isomerization reactor 1 for reaction, and the mixture of pseudotrimethylbenzene and terephthalene is converted into mesitylene.

[0055] Example 9: The difference from Example 8 of this invention is that the reaction temperature of the dealkylation isomerization reactor 1 is 370°C to 380°C, the pressure is 2.5 MPa, and the feed mass hourly space velocity is 6.0 h⁻¹. -1 The molar ratio of hydrogen to C9 and above heavy aromatics is 5:1, and the remaining steps are the same.

[0056] Example 10: The difference from Example 8 of this invention is that the reaction temperature of the dealkylation isomerization reactor 1 is 330°C to 340°C, the pressure is 1.2 MPa, and the feed mass hourly space velocity is 3.0 h⁻¹. -1 The molar ratio of hydrogen to C9 and above heavy aromatics is 4:1, and the remaining steps are the same.

[0057] Example 11: The difference from Example 8 of this invention is that the reaction temperature of the dealkylation isomerization reactor 1 is 350°C to 360°C, the pressure is 1.5 MPa, and the feed mass hourly space velocity is 1.0 h⁻¹. -1 The molar ratio of hydrogen to C9 and above heavy aromatics is 3:1, and the remaining steps are the same.

[0058] Example 12: The difference from Example 8 of this invention is that the reaction temperature of the dealkylation isomerization reactor 1 is 300°C to 310°C, the pressure is 1.0 MPa, and the feed mass hourly space velocity is 4.0 h⁻¹. -1 The molar ratio of hydrogen to C9 and above heavy aromatics is 4:1, and the remaining steps are the same.

[0059] Example 13: The difference from Example 8 of this invention is that the reaction temperature of the dealkylation isomerization reactor 1 is 320°C to 330°C, the pressure is 2.0 MPa, and the feed mass hourly space velocity is 2.0 h⁻¹. -1 The molar ratio of hydrogen to C9 and above heavy aromatics is 6:1, and the remaining steps are the same.

[0060] Example 14: The method for producing mesitylene according to the present invention can ultimately convert C9 and above heavy aromatics into a large amount of mesitylene, a small amount of BTX, and a small amount of C10 and above heavy aromatics. The composition and content of the reaction products obtained by the method for producing mesitylene according to Examples 8 to 13 of the present invention are shown in Table 1. As can be seen from Table 1, after the dealkylation isomerization reaction of C9 and above heavy aromatics, the content of ethylbenzene decreased from 11.49% to below 0.50%, especially the content of o-ethylbenzene decreased to below 0.1%, overcoming the interference of ethylbenzene on mesitylene. The content of trimethylbenzene is greater than 55%, the loss of trimethylbenzene is small, and the yield of mesitylene in the reaction products is greater than 25%. The interference of ethylbenzene and the isomerization of trimethylbenzene can be eliminated in one step, which greatly reduces the difficulty of separating mesitylene and maximizes the production of mesitylene.

[0061] Example 15: As Figure 1As shown, the apparatus for producing mesitylene includes a dealkylation isomerization reactor 1, a high-pressure separator 2, a BTX tower 3, a mesitylene tower 4, and a metasitylene / trimethylammonium tower 5. The top inlet of the dealkylation isomerization reactor 1 is fixedly connected to a C9 and above heavy aromatic hydrocarbon feed line 6. A hydrogen line 7 is fixedly connected to the C9 and above heavy aromatic hydrocarbon feed line 6. A first processing line 8 is fixedly connected between the bottom outlet of the dealkylation isomerization reactor 1 and the side inlet of the high-pressure separator 2. A second processing line 9 is fixedly connected between the bottom outlet of the high-pressure separator 2 and the side inlet of the BTX tower 3. A third processing line 9 is fixedly connected between the top outlet of the high-pressure separator 2 and the C9 and above heavy aromatic hydrocarbon feed line 6. A hydrogen recycling pipeline 10 is fixedly connected to a third processing pipeline 11 between the bottom outlet of BTX tower 3 and the side inlet of mesitylene tower 4; a BTX product conveying pipeline 12 is fixedly connected to the top outlet of BTX tower 3; a fourth processing pipeline 13 is fixedly connected to the bottom outlet of mesitylene tower 4 and the side inlet of terephthalene and terephthalene tower 5; a mesitylene product conveying pipeline 14 is fixedly connected to the top outlet of mesitylene tower 4; a mixture conveying pipeline 16 of terephthalene and terephthalene is fixedly connected to the top outlet of terephthalene and terephthalene tower 5 and the feed pipeline 6 of C9 and above heavy aromatics; and a C10 and above heavy aromatics conveying pipeline 15 is fixedly connected to the bottom outlet of terephthalene and terephthalene tower 5.

[0062] The process of using the apparatus for the method of producing mesitylene according to the present invention is as follows:

[0063] First, C9 and above heavy aromatics are fed into dealkylation isomerization reactor 1 to react with hydrogen to obtain reaction products. The reaction products are then sent to high-pressure separator 2 via first processing pipeline 8 for dehydrogenation separation to obtain hydrogen and liquid products. The hydrogen is then sent back to dealkylation isomerization reactor 1 for reuse.

[0064] Then, the liquid product is sent from the second processing line 9 to the BTX tower 3 for separation to obtain BTX product and C9 and above component products. The BTX product is sent out by the BTX product delivery line 12. The C9 and above component products are sent from the third processing line 11 to the mesitylene tower 4 for separation to obtain mesitylene product and C9 and above component products after removing mesitylene. The mesitylene product is sent out by the mesitylene product delivery line 14. The C9 and above component products after removing mesitylene are sent from the fourth processing line 13 to the metatrimethylbenzene and teremethylbenzene tower 5 for further separation to obtain a mixture of C10 and above heavy aromatics and metatrimethylbenzene and teremethylbenzene. The C10 and above heavy aromatics are sent out by the C10 and above heavy aromatics delivery line 15.

[0065] Finally, the mixture of pseudotrimethylbenzene and terephthalene is returned to the dealkylation isomerization reactor 1 via the pseudotrimethylbenzene and terephthalene mixture transport line 16 for further reaction, whereby the mixture of pseudotrimethylbenzene and terephthalene is converted into mesitylene.

[0066] In summary, this invention employs a dealkylation isomerization process using C9 and higher heavy aromatics, eliminating the interference of ethylbenzene on the separation of mesitylene, maximizing the production of mesitylene, achieving an ethylbenzene content of <0.5%, and a mesitylene yield of greater than 25%. The process is simple, yields high mesitylene, and has low production costs. Compared to traditional routes for producing BTX or blended gasoline, this invention's method for producing mesitylene maximizes the utilization of C9 and higher heavy aromatic resources.

[0067] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

[0068]

Claims

1. A method for producing mesitylene, characterized in that, Perform it as follows: S1, C9 and above heavy aromatics are mixed with hydrogen and then fed into a dealkylation isomerization reactor packed with a catalyst to react and obtain reaction products. The catalyst is a molecular sieve catalyst supported with 0.1 wt% to 5 wt% metal, the molecular sieve support is NKF-5 type molecular sieve, and the metal is one or more of Co, Ni and Mo. During the reaction, the reaction pressure is 1.5 MPa to 2.5 MPa, the molar ratio of hydrogen to C9 and above heavy aromatics is 2 to 4:1, and the reaction temperature is 300℃ to 420℃. S2, the reaction product is sent to a high-pressure separator for dehydrogenation separation to obtain hydrogen and liquid products, and the hydrogen is recycled; S3, the liquid product is sent to the BTX column for separation to obtain BTX product and C9 and above component products. The C9 and above component products are sent from the bottom of the column to the mesitylene column for separation to obtain mesitylene product and C9 and above component products after removing mesitylene. The operating temperature of the BTX column is 162℃ to 164℃, and the operating temperature of the mesitylene column is 165℃ to 167℃. S4, the C9 and above components of the product after removing mesitylene are sent from the bottom of the column to the terephthalene column for further separation to obtain a mixture of C10 and above heavy aromatics, terephthalene and terephthalene, wherein the operating temperature of the terephthalene column is 177℃ to 179℃. S5, the mixture of pseudotrimethylbenzene and terephthalene is returned from the top of the column to the dealkylation isomerization reactor for reaction, whereby the mixture of pseudotrimethylbenzene and terephthalene is converted into mesitylene.

2. The method for producing mesitylene according to claim 1, characterized in that, In step S1, the mass hourly space velocity (MSV) of C9 and higher heavy aromatic hydrocarbons is 1 h⁻¹. -1 up to 6h -1 .

3. The method for producing mesitylene according to claim 1 or 2, characterized in that, The catalyst is obtained by impregnating a molecular sieve support with a metal-containing impregnation solution using an equal-volume impregnation method, followed by drying and calcination.

4. The method for producing mesitylene according to claim 3, characterized in that, The dealkylation isomerization reactor is a fixed-bed reactor.

5. An apparatus for producing mesitylene according to any one of claims 1 to 4, characterized in that, The system includes a dealkylation isomerization reactor, a high-pressure separator, a BTX tower, a mesitylene tower, and a cyclohexylene / trimethylbenzene tower. The top inlet of the dealkylation isomerization reactor is fixedly connected to a feed pipeline for C9 and above heavy aromatics. A hydrogen pipeline is fixedly connected to the C9 and above heavy aromatics feed pipeline. A first processing pipeline is fixedly connected between the bottom outlet of the dealkylation isomerization reactor and the side inlet of the high-pressure separator. A second processing pipeline is fixedly connected between the bottom outlet of the high-pressure separator and the side inlet of the BTX tower. A hydrogen recycling pipeline is fixedly connected between the top outlet of the high-pressure separator and the C9 and above heavy aromatics feed pipeline. A third processing pipeline is fixedly connected between the bottom outlet of the BTX tower and the side inlet of the mesitylene tower. A BTX product conveying pipeline is fixedly connected to the top outlet of the BTX tower. A fourth processing pipeline is fixedly connected between the bottom outlet of the mesitylene tower and the side inlet of the methyltrimethylbenzene and methyltrimethylbenzene towers. A mesitylene product conveying pipeline is fixedly connected to the top outlet of the mesitylene and methyltrimethylbenzene towers. A mixture conveying pipeline of mesitylene and methyltrimethylbenzene is fixedly connected between the top outlet of the mesitylene and methyltrimethylbenzene towers and the feed pipeline for C9 and above heavy aromatics. A C10 and above heavy aromatics conveying pipeline is fixedly connected to the bottom outlet of the mesitylene and methyltrimethylbenzene towers.

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