Method for producing mesitylene from C9 heavy aromatics

Abstract

The invention relates to the technical field of mesitylene production, in particular to a method for producing mesitylene from C9 heavy aromatics, which comprises the following steps of: carrying out hydrodealkylation reaction on C9 heavy aromatics and hydrogen, separating an obtained dealkylation reaction product, returning a gas-phase product to a reverse dealkylation reactor, separating a liquid-phase product, feeding a BTX tower bottom product into a mesitylene tower for separation, and separating the mesitylene from the BTX tower bottom product. A mesitylene tower bottom product enters a mixing tower to be separated, and after a mixing tower top product is subjected to an isomerization reaction, an isomerization reaction product is separated to obtain mesitylene. The process flow is simple, the C9 heavy aromatics are adopted as the raw material, and the combined production process of dealkylation reaction and trimethylbenzene isomerization reaction is adopted, so that side reactions are few, hydrogen consumption is low, by-products can be further utilized, the content of methyl-ethylbenzene in the obtained product is lower than 0.5%, interference of methyl-ethylbenzene on trimethylbenzene separation is eliminated, and the yield of trimethylbenzene is increased. The yield and the purity of mesitylene are improved, the production cost is reduced, and the utilization value of C9 heavy aromatic hydrocarbon resources is improved.

Description

Technical Field

[0001] The invention relates to the technical field of mesitylene production, in particular to a method for producing mesitylene from carbon nine heavy aromatic hydrocarbons. Background Art

[0002] There are nine isomers of C9 aromatics, which can be separated and used as industrial products: mesitylene, unimitation trimethylbenzene, meta-ethylmethylbenzene and para-ethylmethylbenzene. Among them, mesitylene and unimitation trimethylbenzene have the highest added value.

[0003] Mesitylene (1,3,5-trimethylbenzene) is an important chemical raw material. Based on it, a variety of fuel intermediates and important fine chemical products such as trimesic anhydride, mesitylene amine, trimesic acid and terpene alcohol can be produced. Its industrial production methods mainly include synthesis and separation and purification. The synthesis method uses trimethylol as raw material (trimethylol raw material is also mostly separated from reforming or cracking C9 aromatics) to isomerize and generate trimethylol. The separation and purification method uses C9 mixed aromatics produced by catalytic reforming units, para-xylene units, etc. as raw materials to directly separate and extract trimethylol. From the existing technology, the difficulty in producing and separating trimethylol is that there are many substances such as methylbenzene, ethylbenzene, propylbenzene and other carbon nine aromatic isomers and butylbenzene in the raw materials. The boiling point of some carbon nine and above aromatics is very close to trimethylol.

[0004] It is known that among the composition and physical properties of reformed C9 aromatics, the boiling point difference between mesitylene and o-ethylmethylbenzene is only 0.3°C, and it is impossible to separate them by industrial distillation. Moreover, the boiling points of mesitylene, p-ethylmethylbenzene and m-ethylmethylbenzene are also very close, making separation very difficult. The industrial production of mesitylene is also mainly subject to the interference of ethylmethylbenzene. Therefore, simple separation and purification is very difficult and the separation cost is very high. Alkylation, isomerization and other methods can be used to utilize the structural differences between ethylmethylbenzene and mesitylene to achieve component separation with the help of chemical reactions.

[0005] A Chinese patent document with publication number CN103772121A discloses a method for cracking C9 and above heavy aromatic components to produce more trimethylbenzenes, which is a method of dealkylating C9 aromatics by hydrogenation and undergoing alkyl transfer with light aromatics, thereby enriching the trimethylbenzenes in C9 aromatics, and separating light hydrocarbons, BTX, mesitylene and partial trimethylbenzene fractions, carbon nine aromatics and trimethylbenzene fractions, cracking non-aromatic and heavy aromatics, and reducing the difficulty of separation, but failing to obtain the product mesitylene, and having a high yield of light hydrocarbons and BTX, while a low yield of trimethylbenzenes, and the value of the product needs to be further improved.

[0006] A Chinese patent document with publication number CN1139095A discloses a method for separating and preparing mesitylene from C9 mixed aromatics. The method comprises the following steps: firstly subjecting a C9 mixed aromatics raw material having a methyl and ethyl benzene content of greater than 22% to primary distillation, and then using a mixed fraction containing mesitylene, unsymmetrical trimethylolene, and o-, m-, and p-methyl and ethyl benzene as a reaction raw material, adding tert-butyl alcohol, concentrated sulfuric acid, aluminum chloride, and hydrochloric acid, etc., and subjecting the methyl and ethyl benzene to an alkylation reaction and sedimentation treatment, converting the methyl and ethyl benzene into high-boiling products, and then subjecting the product to distillation separation to finally obtain a mesitylene product having a purity greater than 98%. This method converts a large amount of unsymmetrical trimethylolene into alkyl aromatics with a higher carbon number while converting the methyl and ethyl benzene, resulting in a loss of trimethylol. In addition, this method causes severe corrosion to equipment and is difficult to be applied in industry.

[0007] The Chinese patent document with publication number CN1313269A states that heavy aromatics from a reforming unit of an oil refinery need to be continuously distilled through two packed towers to separate a relatively high purity trimethylol fraction, but high purity mesitylene cannot be obtained.

[0008] The Chinese patent document with publication number CN1974500A adopts a three-tower serial process to separate reformed heavy aromatics, which can produce relatively high-purity trimethylolus and co-produce enriched mesitylene with a purity of more than 35%. The purity of mesitylene is relatively low.

[0009] The Chinese patent document with publication number CN102746092A discloses a method for producing mesitylene by hydrocracking and separation of heavy aromatics, which is to mix the heavy aromatics raw material with hydrogen and then enter a ten-membered ring zeolite catalyst filled with precious metals Pt or Pb to carry out a hydrocracking reaction. The reaction product is separated into secondary hydrogen gas and light hydrocarbon components through a high separation tank and a stripping tower, and the liquid hydrocarbon enters the BTX tower to recover BTX, and the heavy component enters the mesitylene tower to separate mesitylene. The remaining C9 aromatics and heavy components are recycled back to the hydrocracking reactor for further cracking, thereby increasing the production of BTX and separating mesitylene. The method has a simple reaction and the product is easy to separate, but the product is mainly BTX (light aromatics), the yield of mesitylene is low, and there are many light hydrocarbon components in the by-product. The yield of mesitylene and the utilization value of heavy aromatics resources need to be further improved.

[0010] Therefore, the process flow of separating and producing mesitylene in the prior art is long and complicated, and the yield of mesitylene is low, the production cost is high, and the industrial application is difficult. If many substances with a boiling point close to that of mesitylene, including methyl ethyl benzene, propyl benzene and other carbon nine aromatic isomers, are removed, the process of separating mesitylene becomes shorter, the equipment is simplified, and the production cost is reduced. Summary of the invention

[0011] The present invention provides a method for producing mesitylene from nine-carbon aromatics, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problems of complex process flow, low mesitylene yield and high production cost in the existing mesitylene production.

[0012] The technical solution of the present invention is achieved by the following measures: A method for producing mesitylene from carbon nine heavy aromatics is carried out according to the following steps: In the first step, a required amount of raw material carbon nine aromatics is mixed with hydrogen, and then sent into a dealkylation reactor equipped with a dealkylation catalyst to perform a hydrogenation dealkylation reaction to obtain a dealkylation reaction product; In the second step, the dealkylation reaction product is separated in a high-pressure separation tank to obtain a liquid phase product and a gas phase product; In the third step, the gas phase product returns to the reverse dealkylation reactor for recycling, and the liquid phase product enters the BTX tower for separation to obtain the BTX tower top product and the BTX tower bottom product; In the fourth step, the BTX tower bottom product enters the mesitylene tower for separation to obtain mesitylene and mesitylene tower bottom product; In the fifth step, the mesitylene bottom product enters a mixing tower for separation to obtain a mixed tower top product and a mixed tower bottom product; Step 6, the top product of the mixed tower is mixed with hydrogen and then enters a trimethylbenzene isomerization reactor equipped with an isomerization catalyst to perform an isomerization reaction to obtain an isomerization reaction product; In the seventh step, the isomerization reaction product is returned to the high-pressure separation tank for separation to obtain mesitylene.

[0013] The following are further optimizations and / or improvements to the above technical solutions: In the first step, the conditions for the hydrodealkylation reaction are: reaction temperature 300°C to 440°C, pressure 0.5MPa to 3.0MPa, mass space velocity 1h -1 Until 6h -1 , hydrogen to oil molar ratio 1 to 4:1.

[0014] In the first step above, in the dealkylation reaction product, the mass ratio of liquefied petroleum gas to the mass ratio of raw material carbon nine-fold aromatics is less than 1%, the mass ratio of light aromatics to the mass ratio of raw material carbon nine-fold aromatics is less than 30%, the mass ratio of methyl and ethyl benzene to the mass ratio of raw material carbon nine-fold aromatics is less than 0.5%, and the dealkylation reaction product does not contain propylbenzene.

[0015] In the above second step, the liquid phase product is a mixture of light aromatics, trimethylbenzene, methyl ethyl benzene, C10 heavy aromatics and a small amount of liquefied petroleum gas, and the gas phase product contains hydrogen and a small amount of methane and ethane, among which the volume content of hydrogen is higher than 90%.

[0016] In the third step, the BTX tower top product includes light aromatics and a small amount of liquefied petroleum gas, and the BTX tower bottom product includes components after light aromatics and liquefied petroleum gas are removed.

[0017] In the fourth step, the bottom product of the mesitylene tower is a mixture of para-trimethylbenzene, tri-trimethylbenzene and C10 heavy aromatic hydrocarbons, and the purity of mesitylene is higher than 98%.

[0018] In the fifth step, the top product of the mixed tower is a mixture of trimethylol and trimethylol, and the bottom product of the mixed tower is C10 heavy aromatics.

[0019] In the above six steps, the conditions for the isomerization reaction are: reaction temperature of 260°C to 360°C, pressure of 0.5MPa to 3.0MPa, mass space velocity of 1h -1 Until 6h -1 , hydrogen to oil molar ratio 1 to 4:1.

[0020] The above-mentioned dealkylation reactor and trimethylbenzene isomerization reactor are both fixed bed reactors.

[0021] The process flow of the invention is simple, and nine-carbon aromatic hydrocarbons are used as raw materials. Through a combined production process of dealkylation reaction and trimethylbenzene isomerization reaction, side reactions are reduced, hydrogen consumption is low, and by-products can be further utilized. The content of methyl and ethyl benzene in the obtained product is less than 0.5%, and the interference of methyl and ethyl benzene on trimethylbenzene separation is eliminated, the yield and purity of trimethylbenzene are improved, the production cost is reduced, and the utilization value of the nine-carbon aromatic hydrocarbon resources is improved. DETAILED DESCRIPTION

[0022] The present invention is not limited by the following embodiments, and the specific implementation method can be determined according to the technical scheme of the present invention and the actual situation. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all chemical reagents and chemicals known and used in the prior art; unless otherwise specified, the percentages in the present invention are all mass percentages; unless otherwise specified, the solutions in the present invention are all aqueous solutions with water as the solvent.

[0023] The present invention will be further described below in conjunction with embodiments: Example 1: The method for producing mesitylene from nine-carbon aromatic hydrocarbons is carried out according to the following steps: In the first step, a required amount of raw material carbon nine aromatics is mixed with hydrogen, and then sent into a dealkylation reactor equipped with a dealkylation catalyst to perform a hydrogenation dealkylation reaction to obtain a dealkylation reaction product; In the second step, the dealkylation reaction product is separated in a high-pressure separation tank to obtain a liquid phase product and a gas phase product; In the third step, the gas phase product returns to the reverse dealkylation reactor for recycling, and the liquid phase product enters the BTX tower for separation to obtain the BTX tower top product and the BTX tower bottom product; In the fourth step, the BTX tower bottom product enters the mesitylene tower for separation to obtain mesitylene and mesitylene tower bottom product; In the fifth step, the mesitylene bottom product enters a mixing tower for separation to obtain a mixed tower top product and a mixed tower bottom product; Step 6, the top product of the mixed tower is mixed with hydrogen and then enters a trimethylbenzene isomerization reactor equipped with an isomerization catalyst to perform an isomerization reaction to obtain an isomerization reaction product; In the seventh step, the isomerization reaction product is returned to the high-pressure separation tank for separation to obtain mesitylene.

[0024] The present invention eliminates the interference of ethylmethylbenzene and maximizes the production of mesitylene by adopting a combined process of dealkylation reaction of carbon nine heavy aromatics (C9) and isomerization reaction of trimethylolbenzene, with the ethylmethylbenzene content being less than 0.5%. The process is simple, the yield of mesitylene is high, the production cost is low, the product value is high, and the product distribution can be flexibly adjusted. Compared with the traditional route of producing BTX or blending gasoline, the utilization value of C9 heavy aromatics resources is significantly improved.

[0025] Example 2: As an optimization of the above example, in the first step, the conditions for the hydrodealkylation reaction are: reaction temperature 300°C to 440°C, pressure 0.5MPa to 3.0MPa, mass space velocity 1h -1 Until 6h -1 , hydrogen to oil molar ratio 1 to 4:1.

[0026] Example 3: As an optimization of the above example, in the first step, in the dealkylation reaction product, the mass ratio of liquefied petroleum gas to the mass ratio of raw material carbon nine-fold aromatics is less than 1%, the mass ratio of light aromatics to the mass ratio of raw material carbon nine-fold aromatics is less than 30%, the mass ratio of methyl and ethyl benzene to the mass ratio of raw material carbon nine-fold aromatics is less than 0.5%, and the dealkylation reaction product does not contain propylbenzene.

[0027] Example 4: As an optimization of the above example, in the second step, the liquid phase product is a mixture of light aromatics, trimethylbenzene, ethylmethylbenzene, C10 heavy aromatics and a small amount of liquefied petroleum gas, and the gas phase product contains hydrogen and a small amount of methane and ethane, wherein the hydrogen volume content is higher than 90%.

[0028] Example 5: As an optimization of the above example, in the third step, the BTX tower top product includes light aromatics and a small amount of liquefied petroleum gas, and the BTX tower bottom product includes components after removing light aromatics and liquefied petroleum gas.

[0029] Example 6: As an optimization of the above example, in the fourth step, the mesitylene bottom product is a mixture of partial trimethylol, trimethylol and C10 heavy aromatics, and the purity of mesitylene is higher than 98%.

[0030] Example 7: As an optimization of the above example, in the fifth step, the top product of the mixed tower is a mixture of trimethylol and trimethylol, and the bottom product of the mixed tower is ten-carbon heavy aromatics.

[0031] Example 8: As an optimization of the above example, in the sixth step, the isomerization reaction conditions are: reaction temperature of 260°C to 360°C, pressure of 0.5MPa to 3.0MPa, mass space velocity of 1h -1 Until 6h -1 , hydrogen to oil molar ratio 1 to 4:1.

[0032] Example 9: As an optimization of the above example, in the sixth step, in the isomerization reaction product, the mass content of methyl and ethyl benzene is less than 0.1%, the mass content of mesitylene is greater than 20%, the mass content of light aromatic hydrocarbons is 1% to 8%, and the mass content of C10 heavy aromatic hydrocarbons is less than 3%.

[0033] Example 10: As an optimization of the above example, the dealkylation reactor and the trimethylbenzene isomerization reactor are both fixed bed reactors.

[0034] Example 11: The carbon nine heavy aromatics with a purity higher than 70% produced by catalytic reforming are subjected to a hydrodealkylation reaction in a dealkylation reactor, and the reaction temperature is controlled to be 310°C to 320°C, the pressure is 1.0 MPa, and the feed weight space velocity is 1.0 h -1 , the feed hydrogen-oil molar ratio is 4:1, the catalyst is loaded in the dealkylation reactor in the form of a fixed bed, the reaction product is dehydrogenated and separated in a high-pressure separation tank, the separated hydrogen is returned to the dealkylation reactor for recycling, the liquid product enters the BTX tower, and the working temperature of the BTX tower is controlled to be 162°C to 164°C (because it is difficult to control the temperature at a specific precise value, so it is appropriate as long as it fluctuates within a certain range, the same below), so that the light components such as LPG (liquefied petroleum gas), BTX (light aromatics), n-propylbenzene, isopropylbenzene, m-ethylethylbenzene, p-ethylmethylbenzene, etc. with a boiling point lower than 164°C are vaporized and discharged from the top of the BTX tower; The components with a boiling point higher than 164°C retained at the bottom of the BTX tower are sent to the mesitylene tower, and the operating temperature of the mesitylene tower is controlled at 165°C to 167°C, so that the mesitylene with a boiling point lower than 167°C and a very small amount of o-methylethylbenzene are discharged from the top of the mesitylene tower; The remaining carbon nine and carbon ten heavy aromatic components with a boiling point higher than 167°C at the bottom of the mesitylene tower are sent to a mixing tower of trimethylol and trimethylol, and the operating temperature of the mixing tower is controlled at 177°C to 179°C. The trimethylol and trimethylol with a boiling point lower than 179°C are separated from the top of the mixing tower, mixed with hydrogen, and then sent to a trimethylol isomerization reactor. The heavy components with a boiling point higher than 179°C at the bottom of the mixing tower are discharged; The isomerization catalyst was loaded in the trimethylbenzene isomerization reactor in the form of a fixed bed, and the reaction temperature was controlled at 270°C to 280°C, the reaction pressure was 1.0 MPa, and the feed weight space velocity was 1.0 h -1 The molar ratio of feed hydrogen to oil is 4:1, and the isomerization reaction product is recycled back to the high-pressure separation tank for separation to obtain mesitylene.

[0035] In Example 11, the compositions of the dealkylation reaction product and the isomerization reaction product are shown in Table 1.

[0036] Example 12: Compared with Example 11, the difference is that in the hydrodealkylation reaction, the reaction temperature is controlled to be 360°C to 380°C, the pressure is 2.0 MPa, and the feed weight space velocity is 2.0 h -1 , the feed hydrogen-to-oil molar ratio is 5:1; The isomerization reaction of trimethylbenzene was carried out by controlling the reaction temperature between 310°C and 320°C, the reaction pressure at 2.0 MPa, and the feed weight space velocity at 2.0 h -1 , the feed hydrogen oil molar ratio is 4: 1. The remaining steps, raw materials and other processes remain unchanged.

[0037] In Example 12, the compositions of the dealkylation reaction product and the isomerization reaction product are shown in Table 1.

[0038] Example 13: Compared with Example 11, the difference is that in the hydrodealkylation reaction, the reaction temperature is controlled to be 330°C to 340°C, the pressure is 0.7MPa, and the feed weight space velocity is 1.0h -1 , the feed hydrogen-to-oil molar ratio is 2:1; The isomerization reaction of trimethylbenzene was carried out at a temperature of 290°C to 300°C, a pressure of 1.2 MPa, and a feed weight space velocity of 2.0 h -1 , the feed hydrogen oil molar ratio is 2: 1. The remaining steps, raw materials and other processes remain unchanged.

[0039] In Example 13, the compositions of the dealkylation reaction product and the isomerization reaction product are shown in Table 1.

[0040] Example 14: Compared with Example 11, the difference is that in the hydrodealkylation reaction, the reaction temperature is controlled to be 310°C to 320°C, the pressure is 1.2 MPa, and the feed weight space velocity is 2.0 h -1 , the feed hydrogen-to-oil molar ratio is 6:1; The isomerization reaction of trimethylbenzene was carried out by controlling the reaction temperature between 270°C and 280°C, the reaction pressure at 1.6 MPa, and the feed weight space velocity at 3.0 h -1 , the feed hydrogen oil molar ratio is 5: 1. The remaining steps, raw materials and other processes remain unchanged.

[0041] In Example 14, the compositions of the dealkylation reaction product and the isomerization reaction product are shown in Table 1.

[0042] Example 15: Compared with Example 11, the difference is that in the hydrodealkylation reaction, the reaction temperature is controlled to be 350°C to 360°C, the pressure is 2.0 MPa, and the feed weight space velocity is 4.0 h -1 , the feed hydrogen-to-oil molar ratio is 4:1; The isomerization reaction of trimethylbenzene was carried out by controlling the reaction temperature between 330°C and 340°C, the reaction pressure at 1.5 MPa, and the feed weight space velocity at 2.0 h -1 , the feed hydrogen oil molar ratio is 4: 1. The remaining steps, raw materials and other processes remain unchanged.

[0043] In Example 15, the compositions of the dealkylation reaction product and the isomerization reaction product are shown in Table 1.

[0044] It can be seen from Table 1 that in Examples 11 to 15 of the present invention, after the dealkylation reaction of C9 heavy aromatics, the content of methyl ethyl benzene can be reduced from 5.42% to 0.18%, a reduction of 96.68%, the content of trimethylbenzene is slightly reduced, and the content of mesitylene in the product can be increased to 16.06% at most, and the ratio of mesitylene to methyl ethyl benzene is greatly improved, especially the content of o-methyl ethyl benzene is reduced to below 0.1%; after the isomerization reaction of para-trimethylbenzene and trimethylbenzene, the content of mesitylene is increased by more than 20%, and there are fewer by-products such as BTX and C10. The isomerized product contains almost no methyl ethyl benzene, which can overcome the interference of methyl ethyl benzene and maximize the production of mesitylene.

[0045] In summary, the process flow of the present invention is simple, and nine-carbon aromatic hydrocarbons are used as raw materials. Through a combined production process of dealkylation reaction and trimethylol isomerization reaction, there are fewer side reactions and low hydrogen consumption. The by-products can be further utilized, and the content of methyl and ethyl benzene in the obtained product is less than 0.5%, eliminating the interference of methyl and ethyl benzene on the separation of trimethylol, improving the yield and purity of trimethylol, reducing production costs, and enhancing the utilization value of nine-carbon aromatic hydrocarbon resources.

[0046] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A method for producing mesitylene from nine-carbon aromatics, Features Follow the steps below: In the first step, a required amount of raw material carbon nine aromatics is mixed with hydrogen, and then sent into a dealkylation reactor equipped with a dealkylation catalyst to perform a hydrogenation dealkylation reaction to obtain a dealkylation reaction product; In the second step, the dealkylation reaction product is separated in a high-pressure separation tank to obtain a liquid phase product and a gas phase product; In the third step, the gas phase product returns to the reverse dealkylation reactor for recycling, and the liquid phase product enters the BTX tower for separation to obtain the BTX tower top product and the BTX tower bottom product; In the fourth step, the BTX tower bottom product enters the mesitylene tower for separation to obtain mesitylene and mesitylene tower bottom product; In the fifth step, the mesitylene bottom product enters a mixing tower for separation to obtain a mixed tower top product and a mixed tower bottom product; Step 6, the top product of the mixed tower is mixed with hydrogen and then enters a trimethylbenzene isomerization reactor equipped with an isomerization catalyst to perform an isomerization reaction to obtain an isomerization reaction product; In the seventh step, the isomerization reaction product is returned to the high-pressure separation tank for separation to obtain mesitylene.

2. The method for producing mesitylene from carbon nine heavy aromatics according to claim 1, Features In the first step, the conditions for the hydrodealkylation reaction are: reaction temperature 300°C to 440°C, pressure 0.5MPa to 3.0MPa, mass space velocity 1h -1 Until 6h -1 , hydrogen to oil molar ratio 1 to 4:

1.

3. The method for producing mesitylene from carbon nine heavy aromatics according to claim 1 or 2, Features In the first step, in the dealkylation reaction product, the mass ratio of liquefied petroleum gas to the mass ratio of raw material carbon nine-fold aromatics is less than 1%, the mass ratio of light aromatics to the mass ratio of raw material carbon nine-fold aromatics is less than 30%, the mass ratio of methyl and ethyl benzene to the mass ratio of raw material carbon nine-fold aromatics is less than 0.5%, and the dealkylation reaction product does not contain propylbenzene.

4. The method for producing mesitylene from carbon nine heavy aromatics according to claim 1, 2 or 3, Features In the second step, the liquid phase product is a mixture of light aromatics, trimethylbenzene, ethylmethylbenzene, C10 heavy aromatics and a small amount of liquefied petroleum gas, and the gas phase product contains hydrogen and a small amount of methane and ethane, among which the volume content of hydrogen is higher than 90%.

5. The method for producing mesitylene from carbon nine heavy aromatics according to claim 1, 2, 3 or 4, Features In the third step, the BTX tower top product includes light aromatics and a small amount of liquefied petroleum gas, and the BTX tower bottom product includes components after the light aromatics and liquefied petroleum gas are removed.

6. The method for producing mesitylene from nine-carbon aromatic hydrocarbons according to any one of claims 1 to 5, Features In the fourth step, the bottom product of the mesitylene tower is a mixture of para-trimethylbenzene, tri-trimethylbenzene and C10 heavy aromatics, and the purity of mesitylene is higher than 98%.

7. The method for producing mesitylene from nine-carbon aromatic hydrocarbons according to any one of claims 1 to 6, Features In the fifth step, the top product of the mixed tower is a mixture of trimethylol and trimethylol, and the bottom product of the mixed tower is C10 heavy aromatics.

8. The method for producing mesitylene from nine-carbon aromatic hydrocarbons according to any one of claims 1 to 7, Features In the sixth step, the isomerization reaction conditions are: reaction temperature of 260°C to 360°C, pressure of 0.5MPa to 3.0MPa, mass space velocity of 1h -1 Until 6h -1 , hydrogen to oil molar ratio 1 to 4:

1.

9. The method for producing mesitylene from nine-carbon aromatic hydrocarbons according to any one of claims 1 to 8, Features In the sixth step, in the isomerization reaction product, the mass content of methyl and ethyl benzene is less than 0.1%, the mass content of mesitylene is greater than 20%, the mass content of light aromatic hydrocarbons is 1% to 8%, and the mass content of C10 heavy aromatic hydrocarbons is less than 3%.

10. The method for producing mesitylene from nine-carbon aromatic hydrocarbons according to any one of claims 1 to 9, Features Both the dealkylation reactor and the trimethylbenzene isomerization reactor are fixed bed reactors.

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