A method for preparing mesitylene

Abstract

This invention provides a method for preparing mesitylene, comprising the following steps: reacting C9 aromatics with methanol in the presence of a catalyst to obtain mesitylene; wherein the reaction temperature is 350–420°C, the reaction pressure is 0.5–5.0 MPa, the molar ratio of methanol to C9 aromatics is 1:1–7:1, and the catalyst is a modified HZSM-5 molecular sieve. In this method for preparing mesitylene, C9 aromatics directly participate in the reaction without separation, resulting in high production efficiency, a short process, and low cost.

Description

Technical Field

[0001] This invention relates to a method for preparing mesitylene and co-producing BTX by directly reacting C9 aromatics with methanol via alkylation. Background Technology

[0002] Aromatic hydrocarbons, as a basic raw material for the petrochemical industry, play an important role in my country's modern national economy. Among them, benzene, toluene, and xylene are the three most basic light aromatic compounds (BTX), which can be used to synthesize a range of chemical products such as plastics, fibers, and rubber.

[0003] Heavy aromatics are byproducts of petroleum and coal processing, primarily C9 and C10 aromatics, mainly derived from catalytic reforming units in oil refineries, wide-fraction catalytic reforming units in polyester plants, ethylene plants, and high-temperature coking units in coal. Their applications vary depending on market demand and separation levels. One important component, 1,2,4,5-tetramethylbenzene (1,2,4,5-Tetramethylbenzene) or Durone (Durene or Durol), is an important organic chemical raw material, primarily used in the production of pyromellitic dianhydride or pyromellitic anhydride, PMDA. Currently, it is mainly separated from C10 aromatics. While C10 heavy aromatics contain a relatively large number of components, 1,2,4,5-tetramethylbenzene, the economically valuable component, comprises only about 8%–9%.

[0004] Chinese patent CN 108722475 A discloses a catalyst for producing mesitylene from pseudotrimethylbenzene and its preparation method. The catalyst uses Na-ZSM-5 molecular sieve as the main component, with other types of molecular sieves as auxiliary agents, and is mixed with a binder and a pore-forming agent in a certain proportion. The mixture is extruded, calcined, and then subjected to ion exchange, high-temperature steam treatment, acid washing, and water washing. Finally, it undergoes halogen and specific metal element impregnation modification to obtain the catalyst product. This catalyst has the advantages of high selectivity for mesitylene and few byproducts. The Si / A ratio of the Na-ZSM-5 molecular sieve is 80, the auxiliary agent is β-molecular sieve, the binder is boehmite, and the pore-forming agent is guar gum powder. The component ratio is molecular sieve main component: auxiliary agent: binder: pore-forming agent = 60:30:9:1. The calcination methods were 350℃ for 3 hours, 500-550℃ for 3 hours, and 600-900℃ for 4 hours, respectively. The resulting catalyst was reacted at 1.0 MPa, 350℃, and 0.1 h⁻¹. The imported feedstock composition was: methanol 21%, 1,2,4-trimethylbenzene 75%, and other components 4%. The single-pass reaction results were: methanol conversion 100%, pseudotrimethylbenzene conversion 49.96%, mesitylene selectivity 47.91%, C1-C2 yield 0.36%, and C3-C4 yield 2.18%.

[0005] Chinese patent CN 107365240 A discloses a method for preparing BTX and co-producing mesitylene from C9+ heavy aromatics. First, the C9+ heavy aromatics are preheated and then fed into a catalytic cracking reactor. Under conditions of 400–600℃, 0.1–1.0 MPa, and a mass hourly space velocity (MHSV) of 0.5–2.5 h⁻¹, they are converted into a first-stage hydrocarbon mixture mainly composed of BTX and tricresylbenzene. This first-stage hydrocarbon mixture is then separated by a deethaner, debutanizer, dehexaneizer, BTX remover, and tricresylbenzene remover to obtain dry gas, liquefied petroleum gas (LPG), C5–C6 non-aromatics, BTX, tricresylbenzene, and C10+ heavy aromatics. The tricresylbenzene and a certain amount of methanol are then fed into an alkylation reactor. Under conditions of 320–480℃, 0.1–1.0 MPa, and a feedstock MHSV of 1.0–4.0 h⁻¹, the reaction proceeds to the alkylation reactor. -1 The reaction of trimethylbenzene and methanol at a molar ratio of 1:1 to 5:1 yields dry gas, wastewater, and liquid hydrocarbons rich in mesitylene. The liquid hydrocarbon product is returned to the deethanizer for further separation. The C10+ heavy components are further separated by a crystallization separation system to obtain mesitylene and heavy component residue. Mesitylene and part of the heavy component residue are used as products, while the remaining heavy component residue is returned to the catalytic cracking reactor. The reaction results of the separated trimethylbenzene with methanol are as follows: BTX yield 53.6%, mesitylene yield 24.3%, dry gas 6.4%, liquefied petroleum gas 5.7%, C5-C6 non-aromatic hydrocarbons 1.1%, and heavy component residue 8.9%. This method has a long process flow and will affect the amount of C9 aromatic hydrocarbons used in the toluene disproportionation unit for existing aromatic hydrocarbon plants.

[0006] The existing technology involves lightening heavy aromatics, followed by high-temperature cracking and separation to obtain products such as BTX and pseudotrimethylbenzene. Pseudotrimethylbenzene is then reacted with methanol to produce mesitylene. This process is lengthy and complex, and further research is needed in this field on the production method of mesitylene. Summary of the Invention

[0007] The main objective of this invention is to provide a method for preparing mesitylene, which overcomes the shortcomings of existing technologies such as excessively long preparation processes, complex procedures, and the need for pre-separation and purification of raw materials.

[0008] To achieve the above objectives, the present invention provides a method for preparing mesitylene, comprising the following steps:

[0009] C9 aromatics are reacted with methanol in the presence of a catalyst to produce mesitylene;

[0010] The reaction temperature is 350–420℃, the reaction pressure is 0.5–5.0 MPa, the molar ratio of methanol to C9 aromatics is 1:1–7:1, and the catalyst is modified HZSM-5 molecular sieve.

[0011] The method for preparing mesitylene according to the present invention, wherein the C9 aromatic hydrocarbon is derived from a catalytic reforming unit, an ethylene unit, or a high-temperature coal coking unit.

[0012] The method for preparing mesitylene according to the present invention, wherein the C9 aromatic hydrocarbons include pseudotrimethylbenzene, ethylbenzene, mesitylene, and terephthalene, wherein, based on the total volume of the C9 aromatic hydrocarbons, the content of pseudotrimethylbenzene is 20-40%, the content of mesitylene is 5-20%, the content of terephthalene is 10-18%, and the content of ethylbenzene is 15-30%.

[0013] The method for preparing mesitylene according to the present invention, wherein the modifying element in the modified HZSM-5 molecular sieve is a metal element or a non-metal element, wherein the metal element is Ga, Zn, Sn, Ni, Mn, Mg, Cr, Cu, Ag, Pd, Ir or Ru, and the non-metal element is P or B.

[0014] The method for preparing mesitylene according to the present invention includes a reaction between C9 aromatic hydrocarbons and methanol carried out in a reactor, wherein the feed mass hourly space velocity (WHSV) of the C9 aromatic hydrocarbons and methanol is 0.1–10.0 h⁻¹. -1 .

[0015] The method for preparing mesitylene according to the present invention, wherein the reactor is a fixed bed or a moving bed reactor.

[0016] The method for preparing mesitylene according to the present invention further includes: separating the reaction mixture obtained by reacting C9 aromatic hydrocarbons with methanol to obtain wastewater, C1-C4 hydrocarbons and C5+ hydrocarbons, wherein the mesitylene is present in the C5+ hydrocarbons.

[0017] The method for preparing mesitylene according to the present invention further includes separating the C5+ hydrocarbon to obtain benzene, toluene, xylene, trimethylbenzene, and C10+ heavy aromatic hydrocarbons, wherein the mesitylene is present in the C10+ heavy aromatic hydrocarbons.

[0018] The method for preparing mesitylene according to the present invention involves crystallizing and separating C10+ heavy aromatic hydrocarbons to obtain mesitylene.

[0019] The method for preparing mesitylene according to the present invention includes a reaction mixture obtained by reacting C9 aromatics with methanol, wherein the mass content of mesitylene reaches 44.01% and the mass content of BTX reaches 33.24%.

[0020] The beneficial effects of this invention are:

[0021] (1) C9 aromatics participate directly in the reaction without separation, resulting in high production efficiency, short process and low cost.

[0022] (2) The reaction product of this invention has a maximum mass content of 44.01% for mesitylene and 33.24% for BTX, which maintains a high BTX yield while efficiently generating mesitylene. Detailed Implementation

[0023] The following provides a detailed description of the embodiments of the present invention. These embodiments are implemented based on the technical solution of the present invention and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0024] This invention provides a method for preparing mesitylene, using C9 aromatics as raw materials, that is, a mixture containing multiple aromatic compounds as raw materials. This eliminates the need for raw material separation, greatly reduces the steps of pre-treatment of raw materials, and simplifies the process.

[0025] The preparation method of mesitylene of the present invention includes the following steps:

[0026] C9 aromatics are reacted with methanol in the presence of a catalyst to produce mesitylene;

[0027] The reaction temperature is 350–420℃, the reaction pressure is 0.5–5.0 MPa, the molar ratio of methanol to C9 aromatics is 1:1–7:1, and the catalyst is modified HZSM-5 molecular sieve.

[0028] The C9 aromatics of this invention can originate from catalytic reforming units, ethylene units, or high-temperature coal coking units. In one embodiment, the C9 aromatics include pseudotrimethylbenzene, ethylbenzene, mesitylene, and terephthalene, wherein, based on the total volume of the C9 aromatics, the pseudotrimethylbenzene content is 20-40%, the mesitylene content is 5-20%, the terephthalene content is 10-18%, and the ethylbenzene content is 15-30%, and may also include 1-5% of other aromatics. Therefore, the C9 aromatics of this invention are a mixture, including at least mesitylene and pseudotrimethylbenzene. Under the action of a catalyst, the methyl group from methanol decomposition adds to the existing aromatics in an alkylation reaction. Simultaneously, the alkyl groups on some of the aromatics in the C9 feedstock also undergo alkyl transfer under the action of the catalyst, thereby generating benzene, toluene, xylene, tetramethylbenzene, etc. Therefore, the method of this invention for preparing mesitylene eliminates the need for separation and purification of the raw C9 aromatics, simplifying the process and producing BTX as a byproduct during the production of mesitylene.

[0029] In one embodiment, the modifying element in the modified HZSM-5 molecular sieve of the present invention is a metallic element or a non-metallic element, wherein the metallic element is Ga, Zn, Sn, Ni, Mn, Mg, Cr, Cu, Ag, Pd, Ir or Ru, and the non-metallic element is P or B.

[0030] This invention does not specifically limit the preparation method of modified HZSM-5 molecular sieve. In one embodiment, the preparation method of modified HZSM-5 molecular sieve includes:

[0031] ZSM-5 molecular sieve products with a silicon-to-aluminum ratio of 30–100 were heated and stirred in an oil bath at 80°C for 12 hours in a 1 mol / L ammonium salt aqueous solution for ion exchange. After washing with deionized water and filtration, the product was dried and then calcined at 450–580°C for 2–8 hours to obtain HZSM-5 with reactive properties.

[0032] The prepared HZSM-5 molecular sieve was uniformly mixed with a binder and extruded into shape. After crushing, sieving, and calcination, granular HZSM-5 was obtained. Then, the HZSM-5 molecular sieve was modified by impregnating the filter cake with a compound solution containing metal or non-metal elements. During the impregnation process, the pH of the impregnation solution was adjusted to 7-8 with ammonia water. After drying, the mixture was calcined at 500-550℃ for 3-5 hours to obtain the modified HZSM-5 molecular sieve catalyst.

[0033] The modifying elements are divided into metallic elements and non-metallic elements; the metallic elements include Ga, Zn, Sn, Ni, Mn, Mg, Cr, Cu, Ag, Pd, Ir, and Ru, and the non-metallic elements include P and B; molecular sieve modification can be single-component modification or modification of two or more components; the total proportion of modifying elements in the modified molecular sieve is 0.5-20% of the mass of the modified molecular sieve.

[0034] The binder can be one or more of the commonly used clays such as kaolin, montmorillonite, and diatomaceous earth; or one or more of the common silicon-based and aluminum-based binders such as alumina, silica, and aluminosilicate sol.

[0035] The ammonium salt can be one or more of ammonium sulfate, ammonium chloride, and ammonium nitrate, with ammonium chloride being preferred.

[0036] The reaction of C9 aromatics with methanol in this invention is carried out in a reactor, and the feed mass hourly space velocity (WHSV) of the C9 aromatics and methanol is 0.1–10.0 h⁻¹. -1 In one embodiment, the reactor is a fixed-bed or moving-bed reactor.

[0037] The method for preparing mesitylene of the present invention further includes: separating the reaction mixture obtained by reacting C9 aromatics with methanol to obtain wastewater, C1-C4 hydrocarbons and C5+ hydrocarbons, wherein the mesitylene is present in the C5+ hydrocarbons. Separating the C5+ hydrocarbons yields benzene, toluene, xylene, trimethylbenzene, and C10+ heavy aromatics, wherein the mesitylene is present in the C10+ heavy aromatics. Crystallizing the C10+ heavy aromatics yields mesitylene.

[0038] Therefore, the present invention provides a method for producing mesitylene by reacting C9 aromatics with methanol, without the need to separately separate mesitylene from C9 aromatics, but can directly use C9 aromatics to react with methanol, producing high yield of BTX while producing mesitylene.

[0039] In one specific embodiment, the preparation method of the present invention for mesitylene includes the following steps:

[0040] (1) C9 aromatics and a certain amount of methanol are introduced into the reactor and react with the catalyst. The reaction is carried out at a temperature of 350–420℃, a pressure of 0.1–3.0 MPa, a molar ratio of methanol to C9 aromatics of 1:1–4:1, and a total feed mass hourly space velocity of 0.1–10.0 h⁻¹. -1 The reaction was carried out under certain conditions to obtain a hydrocarbon mixture rich in BTX and mesitylene.

[0041] The hydrocarbon mixture includes water, C1-C4 hydrocarbons, and other C5+ hydrocarbons;

[0042] (2) After the hydrocarbon mixture is separated by a three-phase separator, wastewater, C1-C4 hydrocarbons and C5+ hydrocarbons are obtained. The wastewater exits the system, and the main components of C1-C4 hydrocarbons are ethylene and propylene, which can be comprehensively utilized.

[0043] (3) After separating the C5+ hydrocarbon material, the main products benzene, toluene, xylene, trimethylbenzene and C10+ heavy aromatic hydrocarbons are obtained. The C10+ heavy aromatic hydrocarbons are separated by mesitylene crystallization to obtain mesitylene.

[0044] In one embodiment, the C1-C4 hydrocarbons are mainly composed of ethylene and propylene, and small amounts of methane, propane, and isobutane.

[0045] This invention uses an alkylation catalyst to directly react C9 aromatics with methanol, which can increase the yield of mesitylene while simultaneously producing high levels of BTX. This achieves the lightening of heavy aromatics and significantly increases the content of mesitylene, which has high utilization value, in the reaction products, thereby improving the economics of C9 aromatics.

[0046] Using the method of the present invention, the mass content of mesitylene in the resulting reaction mixture can reach more than 44%, and the mass content of BTX can reach 33.24%, thus maintaining a high BTX yield while efficiently generating mesitylene.

[0047] The present invention will be further described below with reference to specific embodiments, but it is by no means limited thereto.

[0048] The reaction used C9 aromatics from the top of a heavy aromatics separation tower in a certain factory as raw material, and the specific product composition is shown in Table 1.

[0049] Example 1

[0050] ZSM-5 molecular sieve product with a silicon-to-aluminum ratio of 30 was heated in an oil bath at 80°C and stirred for 12 hours for ion exchange. It was then washed with deionized water, filtered, dried, and calcined at 500°C for 5 hours, followed by loading with 2 wt% Zn. This yielded HZSM-5 with reactive properties.

[0051] The reaction was conducted in a 100 ml fixed-bed apparatus with a methanol to C9 aromatics molar ratio of 2:1, a reaction temperature of 350 °C, a pressure of 0.5 MPa, and a total feed mass hourly space velocity of 1 h⁻¹. -1 The product distribution results under these conditions are shown in Table 3.

[0052] Example 2

[0053] ZSM-5 molecular sieve product with a silicon-to-aluminum ratio of 30 was heated in an oil bath at 80°C and stirred for 12 hours for ion exchange. It was then washed with deionized water, filtered, dried, and calcined at 500°C for 5 hours, followed by loading with 2 wt% Zn. This yielded HZSM-5 with reactive properties.

[0054] The reaction was conducted in a 100 ml fixed-bed apparatus with a methanol to C9 aromatics molar ratio of 3:1, a reaction temperature of 370 °C, a pressure of 0.5 MPa, and a total feed mass hourly space velocity of 1 h⁻¹. -1 The product distribution results under these conditions are shown in Table 3.

[0055] Example 3

[0056] ZSM-5 molecular sieve product with a silicon-to-aluminum ratio of 30 was heated in an oil bath at 85°C and stirred for 12 hours for ion exchange. After washing with deionized water and filtration, it was dried and calcined at 500°C for 5 hours, followed by loading with 3% Zn. This yielded HZSM-5 with reactive properties.

[0057] The reaction was conducted in a 100 ml fixed-bed apparatus with a methanol to C9 aromatics mass ratio of 3:1, a reaction temperature of 400 °C, a pressure of 0.5 MPa, and a total feed mass hourly space velocity of 1 h⁻¹. -1 The product distribution results under these conditions are shown in Table 3.

[0058] Example 4

[0059] ZSM-5 molecular sieve product with a silica-to-alumina ratio of 30 was subjected to ion exchange in a 1 mol / L NH4Cl aqueous solution at 85°C with stirring in an oil bath for 12 h. After washing with deionized water and filtration, the product was dried and calcined at 500°C for 5 h, followed by loading with 3 wt% Zn. This yielded reactive HZSM-5. The reaction was carried out in a 100 ml fixed-bed apparatus with a methanol to C9 aromatics molar ratio of 4:1, a reaction temperature of 370°C, a pressure of 1.0 MPa, and a total feed space velocity of 1 h⁻¹. -1 The product distribution results under these conditions are shown in Table 3.

[0060] Example 5

[0061] ZSM-5 molecular sieve product with a silica-to-alumina ratio of 50 was subjected to ion exchange in a 1 mol / L NH4Cl aqueous solution at 85°C with stirring in an oil bath for 6 hours. After rinsing with deionized water and filtration, the product was dried and calcined at 500°C for 5 hours, followed by loading with 3 wt% Zn. This yielded HZSM-5 with reactive properties.

[0062] The reaction was conducted in a 100 ml fixed-bed apparatus with a methanol to C9 aromatics molar ratio of 3:1, a reaction temperature of 400 °C, a pressure of 0.5 MPa, and a total feed mass hourly space velocity of 1 h⁻¹. -1 The product distribution results under these conditions are shown in Table 3.

[0063] Example 6

[0064] ZSM-5 molecular sieve product with a silicon-to-aluminum ratio of 60 was subjected to ion exchange in a 1 mol / L NH4Cl aqueous solution at 85°C with stirring in an oil bath for 6 hours. After washing with deionized water and filtration, the product was dried and calcined at 500°C for 5 hours, followed by loading with 6 wt% Mg. This yielded the reactive HZSM-5.

[0065] The reaction was conducted in a 100 ml fixed-bed apparatus with a methanol to C9 aromatics molar ratio of 3:1, a reaction temperature of 370 °C, a pressure of 2.0 MPa, and a total feed mass hourly space velocity of 1 h⁻¹. -1 The product distribution results under these conditions are shown in Table 3.

[0066] Example 7

[0067] ZSM-5 molecular sieve product with a silicon-to-aluminum ratio of 150 was subjected to ion exchange in a 1 mol / L NH4Cl aqueous solution at 80°C with stirring in an oil bath for 12 h. After washing with deionized water and filtration, the product was dried and calcined at 500°C for 5 h, followed by loading with 3 wt% Mg. This yielded the reactive HZSM-5.

[0068] The reaction was conducted in a 100 ml fixed-bed apparatus with a methanol to C9 aromatics molar ratio of 3:1, a reaction temperature of 420 °C, a pressure of 3.5 MPa, and a total feed mass hourly space velocity of 1 h⁻¹. -1 The product distribution results under these conditions are shown in Table 3.

[0069] Example 8

[0070] ZSM-5 molecular sieve product with a silica-to-alumina ratio of 300 was subjected to ion exchange in a 1 mol / L NH4Cl aqueous solution at 85°C with stirring in an oil bath for 6 hours. After rinsing with deionized water and filtration, the product was dried and calcined at 500°C for 5 hours, followed by loading with 3 wt% Mg. This yielded the reactive HZSM-5.

[0071] The reaction was conducted in a 100 ml fixed-bed apparatus with a methanol to C9 aromatics molar ratio of 5:1, a reaction temperature of 370 °C, a pressure of 2.0 MPa, and a total feed mass hourly space velocity of 1 h⁻¹. -1 The product distribution results under these conditions are shown in Table 3.

[0072] Example 9

[0073] ZSM-5 molecular sieve product with a silica-to-alumina ratio of 360 was subjected to ion exchange in a 1 mol / L NH4Cl aqueous solution at 85°C with stirring in an oil bath for 6 hours. After rinsing with deionized water and filtration, the product was dried and calcined at 500°C for 5 hours, followed by loading with 2 wt% Mg. This yielded the reactive HZSM-5.

[0074] The reaction was conducted in a 100 ml fixed-bed apparatus with a methanol to C9 aromatics molar ratio of 6:1, a reaction temperature of 400 °C, a pressure of 3.5 MPa, and a total feed mass hourly space velocity of 1 h⁻¹. -1 The product distribution results under these conditions are shown in Table 3.

[0075] Example 10

[0076] ZSM-5 molecular sieve product with a silicon-to-aluminum ratio of 100 was heated in an oil bath at 80°C and stirred for 12 hours for ion exchange. After washing with deionized water and filtration, it was dried and calcined at 500°C for 5 hours, then loaded with 1 wt% P and 3 wt% Zn. This yielded HZSM-5 with reactive properties.

[0077] The reaction was conducted in a 100 ml fixed-bed apparatus with a methanol to C9 aromatics molar ratio of 7:1, a reaction temperature of 370 °C, a pressure of 2.5 MPa, and a total feed mass hourly space velocity of 1 h⁻¹. -1 The product distribution results under these conditions are shown in Table 3.

[0078] Table 1. Composition of C9 aromatic feedstock (wt%)

[0079] sequence n-Alkanes P Isoalkanes Olefins Cycloalkanes N Aromatic A C8 2.743 C9 70.509 C10 0.177 4.107 0.174 16.473 C11 0.721 1.5 0.111 0.824 C12 1.005 1.562 C13 0.097

[0080] The proportion of major aromatic hydrocarbons in C9 aromatic feedstock is shown in Table 2 below.

[0081] Table 2. Proportion of major aromatic hydrocarbons in C9 feedstock (wt%)

[0082]

[0083]

Claims

1. A method for preparing mesitylene, characterized in that, Includes the following steps: C9 aromatics are reacted with methanol in the presence of a catalyst to produce mesitylene; The reaction temperature is 350~420℃, the reaction pressure is 0.5~5.0MPa, the molar ratio of methanol to C9 aromatics is 1:1~7:1, and the catalyst is a modified HZSM-5 molecular sieve, with the modifying elements being Zn, Mg, or a mixture of Zn and P. The C9 aromatics are derived from catalytic reforming units, ethylene units, or high-temperature coal coking units; the C9 aromatics include pseudotrimethylbenzene, ethylbenzene, mesitylene, and terephthalene.

2. The method for preparing mesitylene according to claim 1, characterized in that, Based on the total volume of C9 aromatics, the content of pseudotrimethylbenzene is 20-40%, the content of mesitylene is 5-20%, the content of thionylbenzene is 10-18%, and the content of methyl ethylbenzene is 15-30%.

3. The method for preparing mesitylene according to claim 1, characterized in that, The reaction of C9 aromatics with methanol is carried out in a reactor with a feed mass hourly space velocity (MSV) of 0.1–10.0 h⁻¹. -1 .

4. The method for preparing mesitylene according to claim 3, characterized in that, The reactor is a fixed-bed or moving-bed reactor.

5. The method for preparing mesitylene according to claim 1, characterized in that, Also includes: The reaction mixture obtained by reacting C9 aromatics with methanol is separated to obtain wastewater, C1-C4 hydrocarbons and C5+ hydrocarbons, wherein the mesitylene is present in the C5+ hydrocarbons.

6. The method for preparing mesitylene according to claim 5, characterized in that, It also includes separating the C5+ hydrocarbons to obtain benzene, toluene, xylene, trimethylbenzene, and C10+ heavy aromatics, wherein the mesitylene is present in the C10+ heavy aromatics.

7. The method for preparing mesitylene according to claim 6, characterized in that, Mesitylene was obtained by crystallization and separation of C10+ heavy aromatics.

8. The method for preparing mesitylene according to claim 5, characterized in that, The reaction mixture obtained by reacting C9 aromatics with methanol contains 44.01% by mass of mesitylene and 33.24% by mass of BTX.

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