Method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene

Abstract

The invention discloses a method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene, and relates to the technical field of organic compound preparation. The method comprises the following steps: filling a fixed bed reactor with a modified molecular sieve catalyst, then introducing a mixture of 2-methylnaphthalene and diisopropylbenzene at a certain temperature, pressure and space velocity, carrying out an isopropylation reaction, and carrying out transalkylation to generate 2-isopropyl-6-methylnaphthalene. The 2-methylnaphthalene and diisopropylbenzene mixture is fed, and the solid 2-methylnaphthalene raw material does not need to be heated or a solvent does not need to be used, so that the operation difficulty is reduced. And the ratio of 2-methylnaphthalene to diisopropylbenzene can be changed, so that the conversion rate of 2-methylnaphthalene can be up to 96.0%.

Description

Technical Field

[0001] This invention relates to the field of organic compound preparation technology, specifically to a method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene. Background Technology

[0002] 2-Isopropyl-6-methylnaphthalene (2,6-MIPN) is an important fine chemical product. Its oxidation yields 2,6-naphthalenedicarboxylic acid (2,6-NDCA). 2,6-Naphthalenedicarboxylic acid is used to synthesize polyethylene naphthalate (PEN) and liquid crystal polyester (LCP). Both PEN and LCP are new materials with excellent properties, but their widespread application is limited by the production cost of naphthalenedicarboxylic acid. High-purity 2,6-dialkylnaphthalene is an important raw material for the production of naphthalenedicarboxylic acid.

[0003] Existing methods for synthesizing 2-isopropyl-6-methylnaphthalene include: Japanese Patent (JP 63-243043) proposes a method for synthesizing 2-isopropyl-6-methylnaphthalene by alkylation of 2-methylnaphthalene with propylene, but the selectivity of 2-isopropyl-6-methylnaphthalene is relatively low. Japanese Patent (JP 11-139999) uses 2-methylnaphthalene as a raw material and propylene as an alkylating agent, with a molar ratio of 2-methylnaphthalene to propylene of 1:1.1, and synthesizes 2-isopropyl-6-methylnaphthalene at a temperature of 200–490 °C and a pressure of 1–50 kg / cm² under a solid acid catalyst.

[0004] During the alkylation reaction of 2-methylnaphthalene and propylene, excess propylene will cause propylene molecules to polymerize in the molecular sieve channels, which will significantly shorten the catalyst lifetime. Therefore, the molar ratio of 2-methylnaphthalene to propylene is about 1:1, with only a slight excess of propylene, which limits the further improvement of the conversion rate of 2-methylnaphthalene.

[0005] 2-Methylnaphthalene is a solid at room temperature. Feeding it into a fixed-bed reactor requires either adding a heating element to the equipment or dissolving the 2-methylnaphthalene in a solvent before feeding. The former increases additional equipment costs, while the latter increases energy consumption in subsequent separation processes. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the prior art by providing a method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene. This method is a high-conversion, high-yield alkyltransfer method for preparing 2-isopropyl-6-methylnaphthalene. It utilizes a modified molecular sieve catalyst, and the alkyltransfer reaction between 2-methylnaphthalene and diisopropylbenzene (DIPB, in this invention referring to a mixture of three isomers) yields 2-isopropyl-6-methylnaphthalene with high selectivity. Diisopropylbenzene, as a byproduct of isopropylbenzene, contains two isopropyl groups per molecule and can serve as a source of isopropyl groups. Furthermore, it exhibits good solubility for 2-methylnaphthalene, with a boiling point of 200-210 °C at ambient pressure, allowing 2-methylnaphthalene to be dissolved in diisopropylbenzene and mixed into the feed, thus simplifying the reaction equipment. Additionally, excess isopropyl groups undergo intermolecular alkyltransfer in diisopropylbenzene, unlike propylene which polymerizes, thus improving catalyst lifetime.

[0007] To achieve the above-mentioned objectives, the specific technical solution of the present invention is as follows: A method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene via alkylation, comprising the following steps: A molecular sieve catalyst is loaded into a fixed-bed reactor, and then a mixture of 2-methylnaphthalene and isopropylating agent (diisopropylbenzene) is introduced under certain temperature, pressure and space velocity to carry out the isopropylation reaction. After alkyl transfer, 2-isopropyl-6-methylnaphthalene is generated.

[0008] Furthermore, in the method for preparing 2-isopropyl-6-methylnaphthalene by alkylation of 2-methylnaphthalene, the isopropylating agent includes cumene, three diisopropylbenzene isomers (m-DIPB, o-DIPB, p-DIPB, respectively) or a mixture thereof.

[0009] Furthermore, in the method for preparing 2-isopropyl-6-methylnaphthalene by alkylation of 2-methylnaphthalene, the isopropylating agent is more preferably a mixture of three diisopropylbenzene isomers (m-DIPB, o-DIPB, and p-DIPB, respectively).

[0010] Furthermore, in the method for preparing 2-isopropyl-6-methylnaphthalene by alkylation of 2-methylnaphthalene, the isopropylation reaction conditions are as follows: The reaction temperature is 150~300 ℃ (specifically, it can be 150 ℃, 200 ℃, 250 ℃, 300 ℃, etc.); the reaction pressure is 1~5 MPa (specifically, it can be 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, etc.); the space velocity of 2-methylnaphthalene is 0.01~1 h. -1The molar ratio of 2-methylnaphthalene to diisopropylbenzene (isopropylating agent) is 1:0.5 to 1:10 (specifically, it can be 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.).

[0011] Furthermore, in a method for preparing 2-isopropyl-6-methylnaphthalene by alkylation of 2-methylnaphthalene, the molecular sieve catalyst includes, but is not limited to, Beta, Morden, MCM-22, ZSM-5, and HUSY.

[0012] Furthermore, in a method for preparing 2-isopropyl-6-methylnaphthalene by alkylation of 2-methylnaphthalene, a modified molecular sieve catalyst is more preferably used; The preparation method of the modified molecular sieve catalyst includes the following steps: The molecular sieve was placed in a muffle furnace and calcined for a period of time. The calcined molecular sieve was immersed in an acid solution at room temperature, filtered, and washed with ultrapure water to obtain a solid sample. The obtained solid sample was dried and then calcined in a muffle furnace to obtain the modified molecular sieve catalyst.

[0013] Furthermore, in the preparation method of the modified molecular sieve catalyst, the conditions for calcining the molecular sieve in a muffle furnace are: air atmosphere, calcination temperature of 550±10℃, and calcination time of 3-6 hours (specifically 3 hours, 4 hours, 5 hours, 6 hours, etc.).

[0014] Furthermore, in the preparation method of the modified molecular sieve catalyst, the impregnation time in the organic acid compound at room temperature is 2-24 hours (specifically, it can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, etc.).

[0015] Furthermore, in the method for preparing a modified molecular sieve catalyst, the acid solution comprises any one or a mixture of several organic or inorganic acids. The organic acids include oxalic acid, citric acid, caffeic acid, and EDTA (ethylenediaminetetraacetic acid); the inorganic acids include nitric acid, phosphoric acid, nitrates (such as ammonium nitrate), and phosphates (such as diammonium hydrogen phosphate).

[0016] Furthermore, the acid solution is more preferably an NH4NO3 solution.

[0017] Furthermore, in the method for preparing the modified molecular sieve catalyst, the solid sample is preferably dried in air at 120±5℃.

[0018] The conditions for roasting in the muffle furnace are: air atmosphere, roasting temperature of 550℃±10℃, and roasting time of 3-6 hours (specifically 3 hours, 4 hours, 5 hours, 6 hours, etc.).

[0019] The present invention also protects the use of the modified molecular sieve prepared by the above method in the preparation of 2-isopropyl-6-methylnaphthalene by alkylation of 2-methylnaphthalene.

[0020] Compared with the prior art, the positive effects of the present invention are reflected in: (1) When feeding a mixture of 2-methylnaphthalene and diisopropylbenzene, it is not necessary to heat the solid 2-methylnaphthalene raw material or use a solvent, which reduces the difficulty of operation.

[0021] (2) In this method, the conversion rate of 2-methylnaphthalene can be adjusted by changing the ratio of 2-methylnaphthalene and diisopropylbenzene, and the conversion rate of 2-methylnaphthalene can reach up to 96.0%.

[0022] (3) The use of this modified catalyst enabled the alkyl transfer reaction method to achieve a high conversion rate of 2-methylnaphthalene, resulting in a high yield of 2-isopropyl-6-methylnaphthalene. Detailed Implementation

[0023] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0024] Any feature disclosed in this specification (including the claims and abstract) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0025] In this application, all percentages not explicitly stated represent mass percentage content.

[0026] In this invention, some conventional operating equipment, devices and components have been omitted or only briefly described.

[0027] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0028] The diisopropylbenzene used in the following examples are all three diisopropylbenzene isomers (respectively...) m -DIPB、 o -DIPB、p The mixture of -DIPB) is mixed in the following proportions by mass percentage: m -DIPB45.27%, o -DIPB 3.68%, p -DIPB51.05%.

[0029] Example 1: Preparation of Molecular Sieve Catalysts Preparation of Beta catalysts: NaBeta zeolite molecular sieve powder was calcined in a muffle furnace at 550 °C for 5 h to obtain NaBeta zeolite molecular sieve powder with the organic template removed. The molecular sieve was then reacted with 0.5 mol / L NH4NO3 solution at a ratio of 10 ml / g in a water bath with stirring for 1 h, followed by washing several times with deionized water. The resulting filter cake was dried at 120 °C to obtain NH4β zeolite molecular sieve. The obtained NH4β zeolite molecular sieve was then calcined in a muffle furnace at 550 °C for 5 h to obtain Beta zeolite molecular sieve powder, i.e., the Beta catalyst.

[0030] Preparation of ZSM-5 zeolite molecular sieve catalyst: ZSM-5 zeolite molecular sieve powder was calcined in a muffle furnace at 550 °C for 4 h to obtain ZSM-5 zeolite molecular sieve powder with the organic template removed. The molecular sieve was then exchanged with 0.5 mol / L NH4NO3 solution at a ratio of 10 ml / g in a water bath with stirring for 1 h, followed by washing several times with deionized water. The resulting filter cake was dried at 120 °C to obtain NH4-ZSM-5 zeolite molecular sieve. The obtained NH4-ZSM-5 zeolite molecular sieve was then calcined in a muffle furnace at 550 °C for 5 h to obtain the ZSM-5 catalyst.

[0031] Preparation of MCM-22 zeolite molecular sieve catalyst: MCM-22 zeolite molecular sieve powder was calcined in a muffle furnace at 550 °C for 4 h to obtain MCM-22 zeolite molecular sieve powder with the organic template removed. The molecular sieve was then exchanged with 0.5 mol / L NH4NO3 solution at a ratio of 10 ml / g in a water bath with stirring for 1 h, followed by washing several times with deionized water. The resulting filter cake was dried at 120 °C for 2 h to obtain MCM-22 zeolite molecular sieve. The obtained MCM-22 zeolite molecular sieve was then calcined in a muffle furnace at 550 °C for 4 h to obtain the MCM-22 catalyst.

[0032] Preparation of modified MCM-22 zeolite molecular sieve catalyst: MCM-22 zeolite molecular sieve powder was calcined in a muffle furnace at 550 °C for 4 h to obtain MCM-22 zeolite molecular sieve powder with the organic template removed. The molecular sieve was then exchanged with a 0.5 mol / L NH4NO3 solution at a ratio of 10 ml / g in a water bath with stirring for 1 h. After washing several times with deionized water, the resulting filter cake was dried at 120 °C for 2 h. Next, the molecular sieve was exchanged with a 0.5 mol / L citric acid aqueous solution at a ratio of 10 ml / g in a water bath with stirring for 4 h. After washing several times with deionized water, the resulting filter cake was dried at 120 °C for 2 h to obtain the MCM-22 zeolite molecular sieve. The obtained MCM-22 zeolite molecular sieve was then calcined in a muffle furnace at 550 °C for 4 h to obtain the c-MCM-22 catalyst.

[0033] Preparation of mordenite zeolite molecular sieve catalysts: The mordenite molecular sieve was directly calcined in a muffle furnace at 550 °C for 4 h to obtain the mordenite molecular sieve.

[0034] Preparation of HUSY zeolite molecular sieve catalyst: HUSY zeolite molecular sieve was obtained by directly calcining it in a muffle furnace at 550 °C for 4 h.

[0035] Example 2: 3.0 g of the c-MCM-22 catalyst prepared in Example 1 was loaded into a 10 mL fixed-bed reactor. A mixed solution of 2-methylnaphthalene and diisopropylbenzene was prepared, with a molar ratio of 1:10. The solution was introduced into the reactor using a plunger pump, with the feed material flowing from top to bottom. The reaction temperature was set at 200 °C, and the pressure was maintained at 5.0 MPa. The mass hourly space velocity (WHSV) of 2-methylnaphthalene was 0.1 h⁻¹. -1 After 24 hours of reaction, the liquid product was collected at the end of the apparatus. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0036] Measurements showed that the conversion rate of 2-methylnaphthalene was 52.9%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 62.6%.

[0037] Example 3: 3.0 g of the c-MCM-22 catalyst prepared in Example 1 was loaded into a 10 mL fixed-bed reactor. A mixed solution of 2-methylnaphthalene and diisopropylbenzene was prepared, with a molar ratio of 1:10. The solution was introduced into the reactor using a plunger pump, with the feed material flowing from top to bottom. The reaction temperature was set at 240 °C, and the pressure was maintained at 5.0 MPa. The mass hourly space velocity (WHSV) of 2-methylnaphthalene was 0.1 h⁻¹. -1 The liquid product was collected at the end of the apparatus after 24 hours of reaction. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0038] Measurements showed that the conversion rate of 2-methylnaphthalene was 90.1%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 41.1%.

[0039] Example 4: 3.0 g of the c-MCM-22 catalyst prepared in Example 1 was loaded into a 10 mL fixed-bed reactor. A mixed solution of 2-methylnaphthalene and diisopropylbenzene was prepared, with a molar ratio of 1:10. This solution was introduced into the reactor using a plunger pump, with the feed material flowing from top to bottom. The reaction temperature was set at 280 °C, and the pressure was maintained at 5.0 MPa. The mass hourly space velocity (WHSV) of 2-methylnaphthalene was 0.1 h⁻¹. After a certain reaction time, the liquid product was collected at the end of the apparatus. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0040] Measurements showed that the conversion rate of 2-methylnaphthalene was 96.0%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 19.9%.

[0041] Example 5: 3.0 g of the c-MCM-22 catalyst prepared in Example 1 was loaded into a 10 mL fixed-bed reactor. A mixed solution of 2-methylnaphthalene and diisopropylbenzene was prepared, with a molar ratio of 1:1. This solution was introduced into the reactor using a plunger pump, with the feed material flowing from top to bottom. The reaction temperature was set at 200 °C, and the pressure was maintained at 3.0 MPa. The mass hourly space velocity (WHSV) of 2-methylnaphthalene was 0.01 h⁻¹. -1 The liquid product was collected at the end of the apparatus after 24 hours of reaction. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0042] Measurements showed that the conversion rate of 2-methylnaphthalene was 68.9%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 51.7%.

[0043] Example 6: 3.0 g of c-MCM-22 catalyst was loaded into a 10 mL fixed-bed reactor. A mixed solution of 2-methylnaphthalene and cumene was prepared, with a molar ratio of 1:10. This solution was introduced into the reactor using a plunger pump, with the feed material flowing from top to bottom. The reaction temperature was set at 240 °C, and the pressure was maintained at 5.0 MPa. The mass hourly space velocity (WHSV) of 2-methylnaphthalene was 0.1 h⁻¹. After 24 h of reaction, the liquid product was collected at the end of the apparatus. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0044] Measurements showed that the conversion rate of 2-methylnaphthalene was 11.0%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 52.1%.

[0045] Comparative Example 1: 3.0 g of the c-MCM-22 catalyst prepared in Example 1 was loaded into a 10 mL fixed-bed reactor. A 0.1 g / mL decahydronaphthalene solution was prepared from purified 2-methylnaphthalene feedstock and introduced into the reactor using a plunger pump, with the feedstock flowing from top to bottom. Propylene was introduced into the reactor using a dual-plunger pump. The reaction temperature was set at 200 °C, and the pressure was maintained at 5.0 MPa. The 2-methylnaphthalene mass hourly space velocity (WHSV) was 0.1 h⁻¹. -1 The molar ratio of 2-methylnaphthalene to propylene was 1:1. The liquid product was collected at the end of the apparatus after 24 h of reaction. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0046] Measurements showed that the conversion rate of 2-methylnaphthalene was 44.5%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 63.8%.

[0047] Comparative Example 2: 3.0 g of the c-MCM-22 catalyst prepared in Example 1 was loaded into a 10 mL fixed-bed reactor. A mixed solution of 2-methylnaphthalene and 1,3,5-triisopropylbenzene was prepared, with a molar ratio of 1:10. The solution was introduced into the reactor using a plunger pump, with the feed material flowing from top to bottom. The reaction temperature was set at 240 °C, and the pressure was maintained at 5.0 MPa. The mass hourly space velocity (WHSV) of 2-methylnaphthalene was 0.1 h⁻¹. -1 The liquid product was collected at the end of the apparatus after 24 hours of reaction. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0048] Measurements showed that the conversion rate of 2-methylnaphthalene was 12.6%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 43.9%.

[0049] Comparative Example 3: 3.0 g of the Beta catalyst prepared in Example 1 was loaded into a 10 mL fixed-bed reactor. A mixed solution of 2-methylnaphthalene and diisopropylbenzene was prepared, with a molar ratio of 1:10. The solution was introduced into the reactor using a plunger pump, with the feed material flowing from top to bottom. The reaction temperature was set at 240 °C, and the pressure was maintained at 5.0 MPa. The mass hourly space velocity (WHSV) of 2-methylnaphthalene was 0.1 h⁻¹. -1 The liquid product was collected at the end of the apparatus after 24 hours of reaction. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0050] Measurements showed that the conversion rate of 2-methylnaphthalene was 2.90%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 0%.

[0051] Comparative Example 4: 3.0 g of the mordenite catalyst prepared in Example 1 was loaded into a 10 mL fixed-bed reactor. A mixed solution of 2-methylnaphthalene and diisopropylbenzene was prepared, with a molar ratio of 1:10. The solution was introduced into the reactor using a plunger pump, with the feed material flowing from top to bottom. The reaction temperature was set at 240 °C, and the pressure was maintained at 5.0 MPa. The mass hourly space velocity (WHSV) of 2-methylnaphthalene was 0.1 h⁻¹. -1 The liquid product was collected at the end of the apparatus after 24 hours of reaction. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0052] Measurements showed that the conversion rate of 2-methylnaphthalene was 2.63%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 57.2%.

[0053] Comparative Example 5: 3.0 g of the HUSY catalyst prepared in Example 1 was loaded into a 10 mL fixed-bed reactor. A mixed solution of 2-methylnaphthalene and diisopropylbenzene was prepared, with a molar ratio of 1:10. The solution was introduced into the reactor using a plunger pump, with the feed material flowing from top to bottom. The reaction temperature was set at 240 °C, and the pressure was maintained at 5.0 MPa. The mass hourly space velocity (WHSV) of 2-methylnaphthalene was 0.1 h⁻¹. -1 The liquid product was collected at the end of the apparatus after 24 hours of reaction. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0054] Measurements showed that the conversion rate of 2-methylnaphthalene was 48.87%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 48.98%.

[0055] Comparative Example 6: 3.0 g of the ZSM-5 catalyst prepared in Example 1 was loaded into a 10 mL fixed-bed reactor. A mixed solution of 2-methylnaphthalene and diisopropylbenzene was prepared, with a molar ratio of 1:10. The solution was introduced into the reactor using a plunger pump, with the feed material flowing from top to bottom. The reaction temperature was set at 240 °C, and the pressure was maintained at 5.0 MPa. The mass hourly space velocity (WHSV) of 2-methylnaphthalene was 0.1 h⁻¹. -1 The liquid product was collected at the end of the apparatus after 24 hours of reaction. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0056] Measurements showed that the conversion rate of 2-methylnaphthalene was 2.9%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 0%.

[0057] Comparative Example 7: 3.0 g of the MCM-22 catalyst prepared in Example 1 was loaded into a 10 mL fixed-bed reactor. A mixed solution of 2-methylnaphthalene and diisopropylbenzene was prepared, with a molar ratio of 1:10. The solution was introduced into the reactor using a plunger pump, with the feed material flowing from top to bottom. The reaction temperature was set at 240 °C, and the pressure was maintained at 5.0 MPa. The mass hourly space velocity (WHSV) of 2-methylnaphthalene was 0.1 h⁻¹. -1 The liquid product was collected at the end of the apparatus after 24 hours of reaction. Quantitative analysis of the reactants and products was performed using GC, and qualitative analysis was performed using GC-MS.

[0058] Measurements showed that the conversion rate of 2-methylnaphthalene was 80.72%, and the selectivity of 2-isopropyl-6-methylnaphthalene was 32.78%.

[0059] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0060] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene, characterized in that... Includes the following steps: A molecular sieve catalyst is loaded into a fixed-bed reactor, and then 2-methylnaphthalene and an isopropylating agent are introduced under certain temperature, pressure and space velocity to carry out an isopropylation reaction. After alkyl transfer, 2-isopropyl-6-methylnaphthalene is generated.

2. The method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene according to claim 1, characterized in that: The isopropylating agent includes cumene, three diisopropylbenzene isomers, or a mixture thereof.

3. The method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene according to claim 1, characterized in that, The reaction conditions for isopropylation are: The reaction temperature was 150–300 °C; the reaction pressure was 1–5 MPa; and the space velocity of 2-methylnaphthalene was 0.01–1 h⁻¹. -1 .

4. The method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene according to claim 1, characterized in that: The molar ratio of 2-methylnaphthalene to the isopropylating agent is 1:0.5 to 1:

10.

5. The method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene according to claim 1, characterized in that: The molecular sieve catalyst mentioned is a modified molecular sieve catalyst.

6. The method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene according to claim 2, characterized in that: The isopropylating agent is a mixture of three diisopropylbenzene isomers.

7. The method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene according to claim 1 or 5, characterized in that: The molecular sieves include, but are not limited to, Beta, Mercerized, MCM-22, ZSM-5, and HUSY.

8. The method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene according to claim 5, characterized in that, The preparation method of the modified molecular sieve catalyst includes the following steps: The molecular sieve was placed in a muffle furnace for calcination under air atmosphere, at a temperature of 550±10℃, and for 3-6 hours. The calcined molecular sieve was immersed in an acid solution at room temperature, filtered, and washed with ultrapure water to obtain a solid sample. The obtained solid sample was dried and then calcined in a muffle furnace to obtain the modified molecular sieve catalyst.

9. The method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene according to claim 8, characterized in that, The acid solution is an organic acid or an inorganic acid; the organic acids include oxalic acid, citric acid, caffeic acid, and EDTA; the inorganic acids include nitric acid, phosphoric acid, nitrates, and phosphates; the calcined molecular sieve is immersed in the acid solution at room temperature for 2-24 hours.

10. The method for preparing 2-isopropyl-6-methylnaphthalene from 2-methylnaphthalene according to claim 8, characterized in that, The solid samples were dried in air at 120℃±5℃; the calcination conditions in the muffle furnace were air atmosphere, calcination temperature was 550℃±10℃, and calcination time was 3-6 hours.