Methylnaphthalene alkylation catalyst as well as preparation method and application thereof

Abstract

The invention provides a methylnaphthalene alkylation catalyst as well as a preparation method and application thereof. The methylnaphthalene alkylation catalyst is obtained by carrying out variable-pressure hydrothermal aging and acid pickling on an HMCM-22 molecular sieve; the external specific surface area of the methylnaphthalene alkylation catalyst is 100-140 m < 2 > / g, and the mesoporous volume is 0.8-1.5 cm < 3 > / g; the strong acid center at the temperature of 370-485 DEG C accounts for 80-90% of the weak acid center at the temperature of 200-350 DEG C; the total acid amount is 0.5 to 1.9 [mu] mol / NH3. The methylnaphthalene alkylation catalyst has good stability on the premise of ensuring high activity, is used for catalyzing alkylation of 2-methylnaphthalene and methanol to prepare 2, 6-dimethylnaphthalene, and has good selectivity on DMN and 2, 6-DMN.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical technology, and particularly relates to a methyl naphthalene alkylation catalyst and a preparation method and application thereof. BACKGROUND

[0002] As a new high-performance polyester material, polyethylene naphthalate (PEN) has excellent mechanical properties, heat resistance, gas barrier properties, chemical stability, modulus and dimensional stability, and the like, and the performance is superior to that of traditional polyethylene terephthalate (PET), and is widely used in electronic components, films, packaging, fibers, nanometer plastics, aviation and atomic energy materials, and the like, so it will have huge market space and excellent application prospect in the future, and thus the demand for 2,6-naphthalene dicarboxylic acid, an important raw material for synthesizing PEN, also increases sharply.

[0003] At present, 2,6-naphthalene dicarboxylic acid is mainly prepared by oxidizing 2,6-alkyl naphthalene. Compared with other 2,6-dialkyl naphthalenes (such as 2,6-diethyl naphthalene, 2,6-dibutyl naphthalene and 2,6-dipropyl naphthalene, etc.), 2,6-dimethyl naphthalene (2,6-DMN) is more easily oxidized and no carbon atom is lost in the oxidation process, and is the most suitable raw material for synthesizing 2,6-naphthalene dicarboxylic acid, so 2,6-DMN is an important monomer for synthesizing PEN polyester material.

[0004] Amoco Company developed 2,6-DMN by using o-xylene and butadiene as raw materials, through four-step reactions of side chain alkylation, cyclization, dehydrogenation and isomerization, but the synthesis process is very complex, so the production of 2,6-DMN is small and the cost is high, thereby restricting the application development of PEN. 2,6-DMN can be directly separated and extracted from raw materials containing DMN such as coal tar and petroleum cracking heavy aromatic hydrocarbons, but due to the limited abundance (0.5-5%) of 2,6-DMN in the raw materials, the simple separation and purification route still cannot meet the demand of downstream PEN polyester; meanwhile, other naphthalene components such as naphthalene, methyl naphthalene, dimethyl naphthalene, etc. are also effectively enriched in the process of separating and extracting 2,6-DMN, and the route of synthesizing 2,6-DMN by using molecular sieve to catalyze the alkylation reaction of 2-methyl naphthalene (2-MN) and methanol (CH3OH) has the advantages of simple process, wide raw material sources and low price, and is beneficial to reducing the production cost of PEN. Therefore, the synthesis of 2,6-DMN by using molecular sieve to catalyze the alkylation reaction of 2-MN and CH3OH is a promising synthesis route.

[0005] Among petrochemical raw materials, both catalytic cracking cycle oil (LCO) and ethylene tar are rich in naphthalene-based polycyclic aromatic hydrocarbons, and the production is more than 10 million tons and more than 1 million tons, respectively. At present, the utilization route of LCO mainly includes blending gasoline and diesel oil, and obtaining BTX chemical products through hydroconversion. The utilization route of ethylene tar mainly includes producing petroleum resin, producing carbon fiber through polycondensation, or directly as fuel, etc. Separating and purifying 2,6-DMN from LCO or ethylene tar at the same time, and obtaining 2,6-DMN through catalytic conversion of other naphthalene-based enriched components form a complete process route, which can effectively ensure the yield of 2,6-DMN, further improve the added value of raw materials, meet the current demand of refining transformation to improve high value-added products, and solve the key technology of refining transformation.

[0006] Lijun Jin et al. (Lijun Jin, Yunming Fang, Haoquan Hu; Selective synthesis of 2,6-dimethylnaphthalene by methylation of 2-methylnaphthalene with methanol on Zr / (Al)ZSM-5; Catalysis Communications, 2006, 7(5): 255-259) used (NH4)2ZrF6 to modify HZSM-5 molecular sieve to catalyze 2-MN alkylation reaction, found that Zr atoms replaced part of Al atoms in the framework to reduce the acid strength, which was conducive to the generation of 2,6-DMN, so that the selectivity of 2,6-DMN increased to 56.0%, and the ratio of 2,6- / 2,7-DMN increased to 3.0. Although Zr-modified HZSM-5 showed obvious shape selectivity, the conversion rate of 2-MN was only 10% within 2h, and the conversion rate rapidly decreased with time. Moreover, the HZSM-5 used in this technology has poor activity and stability.

[0007] Jin LJ et al. (Jin LJ, Hu HQ, Wang XY, Liu C; Methylation of 2-methylnaphthalene with methanol to 2,6-dimethylnaphthalene over ZSM-5 modified by Zr and Si; Industrial & Engineering Chemistry Research, 2006, 45(10): 3531-3536) further modified the Zr-modified HZSM-5 with (NH4)2SiF6. The results showed that the stability of the catalyst was improved due to the introduction of Si, and the conversion of 2-MN decreased from 32% at the beginning of the reaction to 20% after 10 h of reaction, and the selectivity of 2,6-DMN was best at 52%. The HZSM-5 molecular sieve used in this technology has poor activity and stability.

[0008] US 5001295A discloses comparative studies of the catalytic performance of HZSM-5 and HMCM-22 molecular sieves in the alkylation of 2-MN with CH3OH, and it is found that, compared with HZSM-5 molecular sieves, the pore diameter (0.41 x 0.51 nm

[001] ) of HMCM-22 molecular sieves is smaller than the molecular diameter of 2-MN (0.58 nm), which makes the alkylation of 2-MN occur in the pores on the outer surface of the molecular sieve, so that the HMCM-22 molecular sieve exhibits better reaction activity and stability, and is expected to realize efficient and stable conversion of 2-MN in industrial production. However, since the alkylation reaction is not limited by the pore, the HMCM-22 molecular sieve exhibits lower selectivity of 2,6-DMN and a lower ratio of 2,6- / 2,7-DMN. In addition, due to the local over-high acidity of the molecular sieve and the uncoordinated ratio of strong and weak acids, methanol is inevitably converted into coke under the catalytic action of the acid centers, which leads to a decrease in reaction stability, and the conversion of 2-MN remains in a downward trend within 240 h of reaction. Although the HMCM-22 molecular sieve catalyzing the alkylation of 2-MN with CH3OH exhibits better reaction activity, the selectivity of DMN and the selectivity of 2,6-DMN are not high, which leads to a low yield of 2,6-DMN. At the same time, the generation of coke leads to a decrease in reaction stability.

[0009] The synthesis of 2,6-DMN by the alkylation of 2-methylnaphthalene with methanol catalyzed by molecular sieves is a promising synthetic route, but since methanol is reactive, it is easy to undergo alkylation side reactions when it encounters solid acid, which promotes the generation of coke and leads to a decrease in reaction stability. SUMMARY

[0010] In order to solve the above problems, the present application aims to provide a methyl naphthalene alkylation catalyst and its preparation method and application, which has good stability under the premise of ensuring high activity, and has good selectivity to DMN and 2, 6-DMN in the preparation of 2, 6-dimethylnaphthalene by catalyzing the alkylation of 2-methylnaphthalene and methanol.

[0011] In order to achieve the above-mentioned purpose, the present application provides a methyl naphthalene alkylation catalyst, which is obtained by pressure swing hydrothermal aging and acid washing of HMCM-22 molecular sieve; the external specific surface area of the methyl naphthalene alkylation catalyst is 100-140m 2 / g, the mesopore volume is 0.8-1.5cm 3 / g; the strong acid center at 370℃-485℃ accounts for 80%-90% of the weak acid center at 200-350℃; and the total acid amount is 0.5-1.9μmol / NH3.

[0012] According to a specific embodiment of the present application, preferably, the total specific surface area of the methyl naphthalene alkylation catalyst is 340-590m 2 / g, the total pore volume is 0.9-1.7cm 3 / g, and the framework aluminum content is 92-96%.

[0013] According to a specific embodiment of the present application, preferably, the total specific surface area of the methyl naphthalene alkylation catalyst is 450-560m 2 / g, the external specific surface area is 105-135m 2 / g, the total pore volume is 0.95-1.21cm 3 / g, the mesopore volume is 0.8-1cm 3 / g; in the Si / Al nuclear magnetic analysis result, the framework aluminum content is 92-96%; in the NH3-TPD analysis result, the strong acid center at 370℃-485℃ accounts for 80%-90% of the weak acid center at 200-350℃; and the total acid amount is 0.9-1.4μmol / NH3.

[0014] According to a specific embodiment of the present application, preferably, the mass ratio of SiO2 / Al2O3 of the methyl naphthalene alkylation catalyst is 25-65.

[0015] The present application also provides a preparation method of the above-mentioned methyl naphthalene alkylation catalyst, which comprises the following steps:

[0016] (1) activating the HMCM-22 molecular sieve at 200-400℃ for 1-4 hours;

[0017] (2) pressure swing hydrothermal aging the activated HMCM-22 molecular sieve, the temperature of pressure swing hydrothermal aging being 300-700℃, and the time being 1-10 hours.

[0018] (3) performing acid washing treatment on the HMCM-22 molecular sieve after pressure swing hydrothermal aging, and then performing drying and calcination to obtain the methylnaphthalene alkylation catalyst.

[0019] According to a specific embodiment of the present application, preferably, the HMCM-22 molecular sieve has a lamellar porous structure.

[0020] According to a specific embodiment of the present application, preferably, in step (1), the SiO2 / Al2O3 mass ratio of the HMCM-22 molecular sieve is 25-65, the total specific surface area is 300-550 m 2 / g, the external specific surface area is 85-125 m 2 / g, the total pore volume is 0.7-1.5 cm 3 / g, and the mesopore volume is 0.6-1.0 cm 3 / g.

[0021] According to a specific embodiment of the present application, preferably, in step (1), the framework aluminum content of the HMCM-22 molecular sieve is 80-90%.

[0022] According to a specific embodiment of the present application, preferably, in step (1), the 370-480℃ strong acid sites of the HMCM-22 molecular sieve account for 91-102% of the 200-350℃ weak acid sites; and the total acid amount is 1.2-2.1 μmol / NH3.

[0023] According to a specific embodiment of the present application, preferably, in step (2), the pressure swing hydrothermal aging is performed by using water vapor, and the pressure swing hydrothermal aging comprises the following steps: introducing 10%-100% water vapor into the reaction tube at an initial pressure of 0.09-0.11 MPa, a pressure increasing rate of 0.1-1 MPa / hour, and a water vapor flow rate of 1-10 ml / hour, and performing pressure swing hydrothermal aging, and the final pressure is ≤4 MPa.

[0024] According to a specific embodiment of the present application, preferably, steps (1) and (2) are operated according to the following steps: placing the HMCM-22 molecular sieve in the reaction tube of the hydrothermal aging device, heating to 200-400℃ at a rate of 5-10℃ / min for activation, and then introducing 10%-100% water vapor into the reaction tube at an initial pressure of 0.1 MPa, a pressure increasing rate of 0.1-1 MPa / hour, and a water vapor flow rate of 1-10 ml / hour, and performing pressure swing hydrothermal aging, and the final pressure is ≤4 MPa.

[0025] According to a specific embodiment of the present application, preferably, in step (3), the acid source used for acid washing includes one or a combination of more than two of hydrochloric acid, acetic acid, and citric acid.

[0026] According to the specific embodiment of the present application, preferably, in step (3), the mass ratio of the acid source solution used in the acid washing to the HMCM-22 molecular sieve subjected to the pressure swing hydrothermal aging is 10-50:1.

[0027] According to the specific embodiment of the present application, preferably, in step (3), the concentration of the acid source solution used in the acid washing is 1-8 mol / L.

[0028] According to the specific embodiment of the present application, preferably, in step (3), the temperature of the acid washing is 30-100℃, and the time is 1-12 hours.

[0029] According to the specific embodiment of the present application, preferably, in step (3), the drying condition is drying at 80-120℃ for 12-24 hours; and the calcination condition is calcination at 400-550℃ for 2-6 hours.

[0030] According to the specific embodiment of the present application, preferably, in step (3), after the acid washing treatment, the HMCM-22 molecular sieve is dried at 80-120℃ for 12-24 hours when the pH of the washing liquid is 6-7, and then is calcined at 400-550℃ for 2-6 hours.

[0031] The present application also provides the use of the above-mentioned methyl naphthalene alkylation catalyst in the preparation of 2,6-dimethyl naphthalene by catalyzing the alkylation of 2-methyl naphthalene with methanol, which comprises the following steps:

[0032] (1) loading the methyl naphthalene alkylation catalyst into a fixed bed reactor, and in-situ activating and pretreating at 200-600℃ for 1-8 hours under a nitrogen atmosphere;

[0033] (2) mixing 2-methyl naphthalene, methanol and a solvent to obtain a raw material liquid; and then introducing the raw material liquid into the fixed bed reactor to contact and react with the catalyst bed to obtain a product containing 2,6-dimethyl naphthalene.

[0034] According to the specific embodiment of the present application, preferably, the molar ratio of methanol to 2-methyl naphthalene is 0.5-2.5, and the mass ratio of 2-methyl naphthalene to the solvent is 2-5.

[0035] According to the specific embodiment of the present application, preferably, the solvent comprises one or a combination of two or more of benzene, toluene, xylene, trimethylbenzene and tetramethylbenzene, and more preferably is mesitylene.

[0036] According to the specific embodiment of the present application, preferably, the reaction temperature is 300-490℃; the reaction pressure is 0-10 MPa (more preferably 0-4 MPa, for example 1-4 MPa); and the mass space velocity of the raw material liquid is 0.2-6.0 h-1 (more preferably 0.5-4.0 h-1, for example 1.0-3.0 h-1) calculated by the mass space velocity of 2-methyl naphthalene.-1 ; more preferably, the reaction temperature is 300-400℃; the mass space velocity of the raw material liquid is 0.2-3.0h -1 .

[0037] The present application adjusts the acidity of the HMCM-22 molecular sieve with a sheet-shaped porous structure by pressure swing hydrothermal aging and acid treatment modification, reduces the acid strength on the premise of not losing a large amount of acid, thereby reducing the side reaction of methanol in the molecular sieve, reducing the generation of carbon deposition, and using the acid washing process to remove amorphous aluminum in the molecular sieve, improving the crystallinity of the molecular sieve, and introducing secondary mesopores, which is more conducive to the diffusion of 2-MN, 2,6-DMN and carbon deposition precursors; the catalyst of the present application effectively controls the acidity, effectively modifies the pore structure, and improves the crystallinity, and at the same time, can keep the initial activity without attenuation for 400h under the premise of ensuring high activity, which has significant industrial application value. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 NH3-TPD graph of the molecular sieve. DETAILED DESCRIPTION

[0039] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the technical solutions of the present application are described in detail as follows, but cannot be understood as limiting the scope of the present application.

[0040] Unless otherwise specified, the raw material molecular sieve (HMCM-22 molecular sieve) used in the following examples and comparative examples is the same as the HMCM-22 molecular sieve used in Comparative Example 1.

[0041] Example 1

[0042] The present embodiment provides a methylnaphthalene alkylation catalyst, which is prepared by the following steps:

[0043] HMCM-22 molecular sieve (SiO2 / Al2O3 mass ratio of 28) was placed in the middle of the stainless steel reaction tube of the hydrothermal aging device, heated to 200°C at a rate of 5°C / min, and activated for 2 h; then, the high-pressure pump was turned on to introduce 80% (initial pressure of 0.1 MPa, pressure increasing rate: 1 MPa / hour, final pressure of 2.1 MPa) water vapor into the reaction tube at a rate of 5 ml / h, and treated at 350°C for 2 h; the pressure-variable hydrothermally aged HMCM-22 molecular sieve was added to 2 mol / L hydrochloric acid solution at a liquid-solid mass ratio of 20:1, heated to 80°C, and soaked for 2 h; then, the acid-treated molecular sieve sample was washed with deionized water, and when the pH of the washing liquid was 6-7, the molecular sieve sample was dried at 80°C for 12 h, calcined at 500°C for 4 h, and the obtained molecular sieve was recorded as HMCM-22-350-2-AT.

[0044] The acid characterization NH3-TPD results of the molecular sieve HMCM-22-350-2-AT are shown in Table 1, the channel characterization results are shown in Table 2, and the crystallinity characterization results are shown in Table 2. Figure 1

[0045] Example 2

[0046] This example provides a methylnaphthalene alkylation catalyst, which is prepared by the following steps:

[0047] HMCM-22 molecular sieve (SiO2 / Al2O3 mass ratio of 28) was placed in the middle of the stainless steel reaction tube of the hydrothermal aging device, heated to 350°C at a rate of 5°C / min, and activated for 2 h; then, the high-pressure pump was turned on to introduce 80% (initial pressure of 0.1 MPa, pressure increasing rate: 0.4 MPa / hour, final pressure of 2.5 MPa) water vapor into the reaction tube at a rate of 5 ml / h, and treated at 550°C for 6 h; the pressure-variable hydrothermally aged HMCM-22 molecular sieve was added to 2 mol / L hydrochloric acid solution at a liquid-solid mass ratio of 20:1, heated to 80°C, and soaked for 2 h; then, the acid-treated molecular sieve sample was washed with deionized water, and when the pH of the washing liquid was 6-7, the molecular sieve sample was dried at 80°C for 12 h, calcined at 500°C for 4 h, and the obtained molecular sieve was recorded as HMCM-22-550-6-AT.

[0048] The acid characterization NH3-TPD results of the molecular sieve HMCM-22-550-6-AT are shown in Table 1, the channel characterization results are shown in Table 2, and the crystallinity characterization results are shown in Table 2. Figure 1

[0049] Example 3

[0050] This example provides a methylnaphthalene alkylation catalyst, which is prepared by the following steps:​​

[0051] HMCM-22 molecular sieve (SiO2 / Al2O3 mass ratio of 28) was placed in the middle of the stainless steel reaction tube of the hydrothermal aging device, heated to 350°C at a rate of 5°C / min, and activated for 2 h; then, the high-pressure pump was turned on to introduce 100% (initial pressure of 0.1 MPa, pressure increasing rate: 0.75 MPa / hour, final pressure of 1.6 MPa) water vapor into the reaction tube at a rate of 6 ml / h, and treated at 350°C for 2 h; the pressure-variable hydrothermally aged HMCM-22 molecular sieve was added to 4 mol / L hydrochloric acid at a liquid-solid mass ratio of 20:1, heated to 80°C, and soaked for 2 h; then, the acid-treated molecular sieve sample was washed with deionized water, and when the pH of the washing liquid was 6-7, the molecular sieve sample was dried at 80°C for 12 h, calcined at 500°C for 4 h, and the obtained molecular sieve was recorded as HMCM-22-350-2-AT-1.

[0052] The acid characterization NH3-TPD results of the molecular sieve HMCM-22-350-2-AT-1 are shown in Table 1, the channel characterization results are shown in Table 2, and the crystallinity characterization results are shown in Table 2. Figure 1

[0053] Example 4

[0054] The present example provides a methylnaphthalene alkylation catalyst, which is prepared by the following steps:

[0055] HMCM-22 molecular sieve (SiO2 / Al2O3 mass ratio of 28) was placed in the middle of the stainless steel reaction tube of the hydrothermal aging device, heated to 350°C at a rate of 5°C / min, and activated for 2 h; then, the high-pressure pump was turned on to introduce 100% (initial pressure of 0.1 MPa, pressure increasing rate: 0.75 MPa / hour, final pressure of 1.6 MPa) water vapor into the reaction tube at a rate of 6 ml / h, and treated at 350°C for 2 h; the pressure-variable hydrothermally aged HMCM-22 molecular sieve was added to 4 mol / L hydrochloric acid at a liquid-solid mass ratio of 20:1, heated to 80°C, and soaked for 2 h; then, the acid-treated molecular sieve sample was washed with deionized water, and when the pH of the washing liquid was 6-7, the molecular sieve sample was dried at 80°C for 12 h, calcined at 500°C for 4 h, and the obtained molecular sieve was recorded as HMCM-22-350-2-AT-1.

[0056] The acid characterization NH3-TPD results of the molecular sieve HMCM-22-450-8-AT are shown in Table 1, the channel characterization results are shown in Table 2, and the crystallinity characterization results are shown in Table 2. Figure 1

[0057] Comparative Example 1

[0058] ​​The comparative example 1 provides a methylnaphthalene alkylation catalyst which is prepared by the following steps: Figure 1 The results of the acid characterization of the molecular sieve HMCM-22-350-4 are shown in Table 1, the results of the channel characterization are shown in Table 2, and the results of the crystallinity characterization are shown in Table 2.

[0059] Comparative example 2

[0060] The comparative example 1 provides a methylnaphthalene alkylation catalyst which is prepared by the following steps:

[0061] The HMCM-22 molecular sieve (SiO2 / Al2O3 mass ratio of 28) is placed in the middle of the stainless steel reaction tube of the hydrothermal aging device, heated to 350°C at a rate of 5°C / min, and activated for 2 h. Then, the high-pressure pump is turned on to introduce 100% (initial pressure of 0.1 MPa, pressure increasing rate: 1 MPa / hour, final pressure of 4.1 MPa) water vapor into the reaction tube at a rate of 5 ml / h, and treated at 350°C for 4 h. The obtained molecular sieve is denoted as HMCM-22-350-4.

[0062] The results of the acid characterization of the molecular sieve HMCM-22-350-4 are shown in Table 1, the results of the channel characterization are shown in Table 2, and the results of the crystallinity characterization are shown in Table 2. Figure 1

[0063] Comparative example 3

[0064] The comparative example 1 provides a methylnaphthalene alkylation catalyst which is prepared by the following steps:

[0065] The HMCM-22 molecular sieve (SiO2 / Al2O3 mass ratio of 28) is placed in the middle of the stainless steel reaction tube of the hydrothermal aging device, heated to 450°C at a rate of 5°C / min, and activated for 2 h. Then, the high-pressure pump is turned on to introduce 100% (0.1 MPa) water vapor into the reaction tube at a rate of 4 ml / h, and treated at 750°C for 2 h. The hydrothermally aged HMCM-22 molecular sieve is added to a 2 mol / L citric acid solution according to a liquid-solid mass ratio of 20:1, heated to 80°C, and soaked for 2 h. Then, the acid-treated molecular sieve sample is washed with deionized water, and when the pH of the washing liquid is 6-7, the molecular sieve sample is dried at 80°C for 12 h, and calcined at 500°C for 4 h. The obtained molecular sieve is denoted as HMCM-22-750-2-AT.

[0066] The results of the acid characterization of the molecular sieve HMCM-22-750-2-AT are shown in Table 1, the results of the channel characterization are shown in Table 2, and the results of the crystallinity characterization are shown in Table 2. Figure 1

[0067] ​​Reaction evaluation

[0068] Test Example 1

[0069] This test example investigates the catalytic performance of HMCM-22-350-2-AT molecular sieve in the alkylation of 2-methylnaphthalene, using a stainless steel reactor with an inner diameter of 10 mm, and a reaction pressure of 2.5 MPa, in accordance with the following specific process:

[0070] 5.0 g of the molecular sieve catalyst was loaded into the reactor; then, in-situ activation pretreatment was carried out at 200°C for 7 h under a nitrogen atmosphere; next, the raw material liquid was prepared in accordance with the ratio of methanol / 2-methylnaphthalene = 1.02 (mol / mol), 2-methylnaphthalene / (2-methylnaphthalene + 1,3,5-trimethylbenzene) = 0.8 (wt / wt), and was mixed uniformly; the raw material liquid was introduced into the reactor to contact the catalyst bed layer using a metering pump, and the reaction conditions were as follows: a temperature of 350°C, a pressure of 2.5 MPa, and a space velocity (based on the mass of 2-methylnaphthalene) of 0.3 h -1 The product was sampled after condensation and analyzed on a gas chromatograph, and the reaction results are shown in Table 3.

[0071] Test Example 2

[0072] This test example investigates the catalytic performance of HMCM-22-550-6-AT molecular sieve in the alkylation of 2-methylnaphthalene, using a stainless steel reactor with an inner diameter of 10 mm, and a reaction pressure of 2.5 MPa, in accordance with the following specific process:

[0073] 5.0 g of the molecular sieve catalyst was loaded into the reactor; then, in-situ activation pretreatment was carried out at 200°C for 7 h under a nitrogen atmosphere; next, the raw material liquid was prepared in accordance with the ratio of methanol / 2-methylnaphthalene = 1.02 (mol / mol), 2-methylnaphthalene / (2-methylnaphthalene + 1,3,5-trimethylbenzene) = 0.8 (wt / wt), and was mixed uniformly; the raw material liquid was introduced into the reactor to contact the catalyst bed layer using a metering pump, and the reaction conditions were as follows: a temperature of 350°C, a pressure of 2.5 MPa, and a space velocity (based on the mass of 2-methylnaphthalene) of 0.3 h -1 The product was sampled after condensation and analyzed on a gas chromatograph, and the reaction results are shown in Table 3.

[0074] Test Example 3

[0075] This test example investigates the catalytic performance of HMCM-22-350-2-AT-1 molecular sieve in the alkylation of 2-methylnaphthalene, using a stainless steel reactor with an inner diameter of 10 mm, and a reaction pressure of 2.5 MPa, in accordance with the following specific process:

[0076] 5.0 g of molecular sieve catalyst was loaded into the reactor; then, it was pretreated in situ at 200 °C for 7 h under a nitrogen atmosphere; next, a feed solution was prepared according to the ratio of methanol / 2-methylnaphthalene = 1.02 (mol / mol) and 2-methylnaphthalene (2-methylnaphthalene + 1,3,5-trimethylbenzene) = 0.8 (wt / wt), and the mixture was homogeneous; the feed solution was introduced into the reactor into contact with the catalyst bed using a metering pump, and the reaction conditions were: temperature 350 °C, pressure 2.5 MPa, and space velocity (based on the mass of 2-methylnaphthalene) 0.3 h⁻¹. -1 The product was condensed and sampled for analysis using a gas chromatograph. The reaction results are shown in Table 3.

[0077] Test Example 4

[0078] This test case investigated the catalytic performance of HMCM-22-450-8-AT molecular sieve in the alkylation of 2-methylnaphthalene in a fixed-bed reactor. A 10mm inner diameter stainless steel reactor was used, and the reaction pressure was 2.5MPa. The specific process is as follows:

[0079] 5.0 g of molecular sieve catalyst was loaded into the reactor; then, it was pretreated in situ at 200 °C for 7 h under a nitrogen atmosphere; next, a feed solution was prepared according to the ratio of methanol / 2-methylnaphthalene = 1.02 (mol / mol) and 2-methylnaphthalene / (2-methylnaphthalene + 1,3,5-trimethylbenzene) = 0.8 (wt / wt), and the mixture was homogeneous; the feed solution was introduced into the reactor into contact with the catalyst bed using a metering pump, and the reaction conditions were: temperature 350 °C, pressure 2.5 MPa, and space velocity (based on the mass of 2-methylnaphthalene) 0.3 h⁻¹. -1 The product was condensed and sampled for analysis using a gas chromatograph. The reaction results are shown in Table 3.

[0080] Comparative Test Example 1

[0081] This comparative test case investigated the catalytic performance of HMCM-22 molecular sieve in the alkylation of 2-methylnaphthalene in a fixed-bed reactor. A 10mm inner diameter stainless steel reactor was used, and the reaction pressure was 2.5MPa. The specific process is as follows:

[0082] 5.0 g of molecular sieve catalyst was loaded into the reactor; then, it was pretreated in situ at 200 °C for 7 h under a nitrogen atmosphere; next, a feed solution was prepared according to the ratio of methanol / 2-methylnaphthalene = 1.02 (mol / mol) and 2-methylnaphthalene (2-methylnaphthalene + 1,3,5-trimethylbenzene) = 0.8 (wt / wt), and the mixture was homogeneous; the feed solution was introduced into the reactor into contact with the catalyst bed using a metering pump, and the reaction conditions were: temperature 350 °C, pressure 2.5 MPa, and space velocity (based on the mass of 2-methylnaphthalene) 0.3 h⁻¹. -1 The product was condensed and sampled for analysis using a gas chromatograph. The reaction results are shown in Table 3.

[0083] Comparative Test Example 2

[0084] This comparative test example investigates the catalytic performance of HMCM-22-350-4 molecular sieve in the alkylation of 2-methylnaphthalene in a fixed bed reactor. A stainless steel reactor with an inner diameter of 10 mm is used, and the reaction pressure is 2.5 MPa. The specific process is as follows:

[0085] 5.0 g of the molecular sieve catalyst is loaded into the reactor, then in-situ activation pretreatment is carried out at 200°C for 7 h under a nitrogen atmosphere. Next, the raw material solution is prepared according to the ratio of methanol / 2-methylnaphthalene = 1.02 (mol / mol), 2-methylnaphthalene / (2-methylnaphthalene + 1,3,5-trimethylbenzene) = 0.8 (wt / wt), and mixed uniformly. The raw material solution is introduced into the reactor to contact the catalyst bed by a metering pump, and the reaction conditions are as follows: temperature 350°C, pressure 2.5 MPa, space velocity (based on the mass of 2-methylnaphthalene) 0.3 h -1 The product is sampled after condensation and analyzed on a gas chromatograph, and the reaction results are shown in Table 3.

[0086] Comparative Test Example 3

[0087] This comparative test example investigates the catalytic performance of HMCM-22-750-2-AT molecular sieve in the alkylation of 2-methylnaphthalene in a fixed bed reactor. A stainless steel reactor with an inner diameter of 10 mm is used, and the reaction pressure is 2.5 MPa. The specific process is as follows:

[0088] 5.0 g of the molecular sieve catalyst is loaded into the reactor, then in-situ activation pretreatment is carried out at 200°C for 7 h under a nitrogen atmosphere. Next, the raw material solution is prepared according to the ratio of methanol / 2-methylnaphthalene = 1.02 (mol / mol), 2-methylnaphthalene / (2-methylnaphthalene + 1,3,5-trimethylbenzene) = 0.8 (wt / wt), and mixed uniformly. The raw material solution is introduced into the reactor to contact the catalyst bed by a metering pump, and the reaction conditions are as follows: temperature 350°C, pressure 2.5 MPa, space velocity (based on the mass of 2-methylnaphthalene) 0.3 h -1 The product is sampled after condensation and analyzed on a gas chromatograph, and the reaction results are shown in Table 3.

[0089] Table 1

[0090]

[0091] Table 2

[0092]

[0093] Table 3

[0094]

[0095] In Table 3, the 2-MN conversion rate (x, %), the DMN selectivity (s DMN , %), and the 2,6-DMN selectivity (s 2,6-DMN , %) are calculated according to the following formula:

[0096] X = (1 - m2-MN - m1-MN x 100%

[0097]

[0098]

[0099] In the above formula, m 2-MN , m 1-MN , m 2,6-DMN , and m DMN respectively represent the mass fraction of 2-MN, 1-MN, 2,6-DMN, and DMN in the product.

[0100] In combination with Test Examples 1, 3-4 and Comparative Test Examples 1, 4, the pore structure of the molecular sieve catalyst subjected to hydrothermal aging and acid treatment is effectively optimized, and the increase in the external pore surface area is more conducive to the diffusion of reactants, thereby achieving a higher reaction conversion rate. The results of Comparative Example 2 and Comparative Test Example 2 show that the molecular sieve catalyst not subjected to acid treatment has more amorphous aluminum, which causes the blockage of the catalyst pores, thereby affecting the reaction conversion rate and stability. The results of Comparative Example 3 and Comparative Test Example 3 show that the use of a higher hydrothermal treatment temperature leads to a large loss of the total acid amount of the catalyst, a decrease in the active sites of the catalyst, and a significant decrease in the reaction conversion rate and stability.

[0101] As can be seen from the data in Tables 1-3 and Figure 1 , the 2-methylnaphthalene conversion rate of the catalyst of the present application used in the 2-methylnaphthalene alkylation reaction can reach more than 42%, the DMN selectivity is 55%-60%, and the 2,6-DMN selectivity is 12%-15%. At the same time, the catalyst has good reaction stability, and the methylnaphthalene conversion rate of the molecular sieve subjected to hydrothermal aging and acid treatment is maintained stable within 400h of the catalytic alkylation reaction, which can meet the requirements of industrial application and is convenient for large-scale industrial production.

[0102] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the present application and fall within the protection scope of the present application.

Claims

1. A methyl naphthalene alkylation catalyst, which is obtained by pressure swing hydrothermal aging and acid washing of HMCM-22 molecular sieve. The methyl naphthalene alkylation catalyst has an external specific surface area of 100-140 m 2 / g, a mesopore volume of 0.8-1.5 cm 3 / g; 370℃-485℃ strong acid centers account for 80%-90% of 200-350℃ weak acid centers; and a total acid amount of 0.5-1.9 μmol / NH3.

2. The methylnaphthalene alkylation catalyst of claim 1, wherein, The total specific surface area of the methylnaphthalene alkylation catalyst is 340-590 m 2 / g, and the total pore volume is 0.9-1.7 cm 3 / g, and the skeletal aluminum proportion is 92-96%. 3.A method for preparing the methyl naphthalene alkylation catalyst according to claim 1 or 2, comprising the following steps: (1) activating the HMCM-22 molecular sieve at 200-400℃ for 1-4 hours; (2) pressure swing hydrothermal aging the activated HMCM-22 molecular sieve at 300-700℃ for 1-10 hours; (3) acid washing the pressure swing hydrothermal aged HMCM-22 molecular sieve, and then drying and calcining to obtain the methyl naphthalene alkylation catalyst.

4. The production method according to claim 3, wherein In step (1), the mass ratio of SiO2 / Al2O3 of the HMCM-22 molecular sieve is 25-65, the total specific surface area is 300-550 m 2 / g, the external specific surface area is 85-125 m 2 / g, the total pore volume is 0.7-1.5 cm 3 / g, and the mesopore volume is 0.6-1.0 cm 3 / g.

5. The production method according to claim 3, wherein In step (1), the framework aluminum content of the HMCM-22 molecular sieve is 80-90%; and / or, the 370-480℃ strong acid sites of the HMCM-22 molecular sieve account for 91-102% of the 200-350℃ weak acid sites; the total acid amount is 1.2-2.1μmol / NH3.

6. The production method according to claim 3, wherein In step (2), the pressure swing hydrothermal aging is performed using water vapor, and the pressure swing hydrothermal aging comprises the following steps: introducing 10%-100% water vapor into the reaction tube at an initial pressure of 0.09-0.11MPa, a pressure increase rate of 0.1-1MPa / h, and a water vapor flow rate of 1-10ml / h, and the final pressure is ≤4MPa.

7. The production method according to claim 3, wherein In step (3), the acid source used for acid washing includes one or a combination of more than two of hydrochloric acid, acetic acid, and citric acid; and / or, in step (3), the mass ratio of the acid source solution to the pressure swing hydrothermal aged HMCM-22 molecular sieve is 10-50:1; and / or, in step (3), the concentration of the acid source solution used for acid washing is 1-8mol / L.

8. The production method according to claim 3, wherein In step (3), the acid washing temperature is 30-100℃, and the acid washing time is 1-12 hours; and / or, the calcination conditions are calcination at 400-550℃ for 2-6h. 9.Use of the methyl naphthalene alkylation catalyst according to claim 1 or 2 in the catalytic alkylation of 2-methylnaphthalene with methanol to prepare 2,6-dimethylnaphthalene, which comprises the following steps: (1) loading the methyl naphthalene alkylation catalyst into a fixed bed reactor, and in-situ activating and pretreating at 200-600℃ under a nitrogen atmosphere for 1-8h; (2) mixing 2-methylnaphthalene, methanol, and a solvent to obtain a raw material solution; then introducing the raw material solution into the fixed bed reactor to react with the catalyst bed layer to obtain a product containing 2,6-dimethylnaphthalene.

10. Use according to claim 9, wherein, The molar ratio of methanol to 2-methylnaphthalene is 0.5-2.5, and the mass ratio of 2-methylnaphthalene to the solvent is 2-5. And / or, the reaction temperature is 300-490℃; the reaction pressure is 0-10 MPa; the mass space velocity of the raw material liquid is 0.2-6.0 h -1 .

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