A zsm-22 molecular sieve, a preparation method and application thereof

Abstract

The application provides a ZSM-22 molecular sieve, a preparation method and application thereof, wherein the total 2,6-dimethylpyridine infrared B acid amount of the ZSM-22 molecular sieve is 0.07-0.51 mmol / g, preferably 0.08-0.49 mmol / g; in the 2,6-dimethylpyridine infrared B acid, the B acid amount with a desorption temperature > 420 DEG C is 0-0.12 mmol / g, preferably 0.01-0.10 mmol / g; preferably, the ratio of the B acid amount with a desorption temperature > 420 DEG C to the total 2,6-dimethylpyridine infrared B acid amount is 0-22:100, preferably 2-20:100. The ZSM-22 molecular sieve has less strong B acid sites on the outer surface and the pore mouth, and when applied to a hydroisomerization reaction process, the yield and quality of the target product can be greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of molecular sieve preparation technology, and relates to a ZSM-22 molecular sieve, its preparation method and application. Background Technology

[0002] As a microporous silica-alumina molecular sieve, ZSM-22 molecular sieve possesses one-dimensional channels composed of ten-membered rings, parallel to the (001) direction. Due to its unique channel structure, ZSM-22 molecular sieve exhibits excellent catalytic performance when applied in the field of shape-selective catalysis. The synthesis of ZSM-22 molecular sieve typically uses organic amines such as ethylenediamine and 1,6-hexanediamine as template agents, resulting in products with strong β-acidic sites. Researchers often adjust the acidity of ZSM-22 molecular sieves by optimizing the synthesis method or post-processing techniques to further improve its catalytic performance.

[0003] Patent CN104211080A discloses a method for preparing Fe isomorphously substituted ZSM-22 molecular sieve. The method includes the following steps: (1) preparing aqueous solutions of an aluminum source, an alkali source, a silicon source, and a template agent, respectively, mixing them, and aging them to obtain a directing agent; (2) further preparing aqueous solutions of the aluminum source, the alkali source, the silicon source, and the iron source, respectively, and mixing them with the directing agent to obtain an initial gel; the initial gel is crystallized in a crystallization reactor to obtain the Fe isomorphically substituted ZSM-22 molecular sieve.

[0004] The article (Zhang Xiaoxiao et al., Applied Chemical Engineering, 2019, 48(07):1516-1520) first treated ZSM-22 molecular sieve with a certain concentration of Na2CO3 solution, and then acid washed with HCl solution. The acid content and acid strength of ZSM-22 molecular sieve were reduced by alkaline acid treatment.

[0005] The above methods can only generally remove or weaken the strong Brønsted acid sites of ZSM-22 molecular sieves, and have limited ability to adjust acidity. When the obtained ZSM-22 molecular sieves are applied to the hydroisomerization reaction process, the yield and quality of the target product need to be further improved. Summary of the Invention

[0006] During their research, the inventors discovered that if there are many strong Brønsted acid sites on the outer surface and pores of ZSM-22 molecular sieve, it will promote side reactions such as cracking during the hydroisomerization reaction, thereby affecting the yield and quality of the target product.

[0007] Based on the above research results, this invention provides a ZSM-22 molecular sieve, its preparation method, and its application. The ZSM-22 molecular sieve has fewer strong β-acid sites on its outer surface and pores, which can significantly improve the yield and quality of the target product when applied in a hydroisomerization reaction process.

[0008] The first aspect of the present invention provides a ZSM-22 molecular sieve, wherein the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy in the ZSM-22 molecular sieve is 0.07–0.51 mmol / g, preferably 0.08–0.49 mmol / g; in the Brønsted acid of 2,6-dimethylpyridine infrared spectroscopy, the amount of Brønsted acid with a desorption temperature >420°C is 0–0.12 mmol / g, preferably 0.01–0.10 mmol / g; preferably, the ratio of the amount of Brønsted acid with a desorption temperature >420°C to the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 0–22:100, more preferably 2–20:100.

[0009] In the ZSM-22 molecular sieve described above, the total β-carboxylic acid content of pyridine in infrared spectroscopy is 0.10–0.54 mmol / g, preferably 0.12–0.52 mmol / g; preferably, the ratio of the total β-carboxylic acid content of 2,6-dimethylpyridine in infrared spectroscopy to the total β-carboxylic acid content of pyridine in infrared spectroscopy in the ZSM-22 molecular sieve is 67–95:100, more preferably 70–93:100.

[0010] A second aspect of this invention provides a method for preparing ZSM-22 molecular sieve, the method comprising the following steps:

[0011] (1) A mixture of silicon source, template agent 1 and water is subjected to a crystallization reaction, and the solid phase material is separated from the material after the reaction.

[0012] (2) The solid material obtained in step (1), the fatty amine and the inorganic base are mixed and subjected to a first low temperature treatment. Then, ZSM-22 seed crystals are added and subjected to a second low temperature treatment to obtain a mixture.

[0013] (3) Mix the aluminum source, template agent 2 and the mixture obtained in step (2), and then crystallize, filter, wash, dry and calcine in sequence to obtain the final ZSM-22 molecular sieve.

[0014] In step (1) of the above method, the silicon source is one or more of silica, silica sol, water glass, fumed silica, and tetraethyl orthosilicate, preferably silica sol and / or fumed silica.

[0015] In step (1) of the above method, the template agent 1 is one or more of hexamethylenediamine, ethanol, and n-hexamethylenediamine, preferably hexamethylenediamine and / or ethanol.

[0016] In step (1) of the above method, the molar ratio of water, template agent 1 and silicon source (calculated as SiO2) is (20-80):(0.1-1):1, preferably (30-70):(0.15-0.8):1.

[0017] In step (1) of the above method, the crystallization reaction conditions are as follows: the crystallization temperature is 120-220℃, the crystallization time is 8-48h, and the preferred crystallization temperature is 140-200℃ and the crystallization time is 12-30h.

[0018] In step (2) of the above method, the fatty amine is a C12-C18 fatty amine, preferably one or more of oleylamine, octadecylamine, and dodecylamine; the liquid-solid ratio of the fatty amine to the solid material obtained in step (1) is 0.3-3 mL / g, preferably 0.5-2.0 mL / g.

[0019] In step (2) of the above method, the inorganic base is any one of sodium hydroxide, potassium hydroxide and ammonia water.

[0020] In step (2) of the above method, the inorganic alkali is used in the form of an alkaline solution, the concentration of which is 0.003 to 0.015 mol / L, preferably 0.005 to 0.010 mol / L; the liquid-solid ratio of the alkaline solution to the solid material obtained in step (1) is 2 to 20 mL / g, preferably 5 to 15 mL / g.

[0021] In step (2) of the above method, based on the weight of the solid material obtained in step (1), the amount of ZSM-22 seed crystals added is 0.1 to 8.0 wt%, preferably 0.5 to 5.0 wt%.

[0022] In step (2) of the above method, the temperature of the first low-temperature treatment is 20-40℃ and the time is 3-15h; the temperature of the second low-temperature treatment is 60-120℃ and the time is 6-30h; preferably, the temperature of the second low-temperature treatment is higher than the temperature of the first low-temperature treatment.

[0023] In step (3) of the above method, the aluminum source is one or more of aluminum sulfate, aluminum isopropoxide, sodium aluminate and aluminum hydroxide, preferably aluminum sulfate; the molar ratio of the aluminum source (calculated as Al2O3) to the solid material obtained in step (1) (calculated as SiO2) is 0.002 to 0.015, preferably 0.005 to 0.01.

[0024] In step (3) of the above method, the template agent 2 is one or more of 1,6-hexanediamine and ethylenediamine, preferably ethylenediamine; the molar ratio of the template agent 2 to the solid material (calculated as SiO2) obtained in step (1) is 0.05 to 0.25, preferably 0.08 to 0.20.

[0025] In step (3) of the above method, the crystallization temperature is 180-220℃ and the crystallization time is 24-72h.

[0026] In step (3) of the above method, the drying temperature is 80-120℃ and the drying time is 6-12h; the calcination temperature is 540-560℃ and the calcination time is 3-8h.

[0027] The third aspect of this invention provides the application of the above-mentioned ZSM-22 molecular sieve in the hydroisomerization reaction process.

[0028] Compared with the prior art, the ZSM-22 molecular sieve, its preparation method and application of the present invention have the following advantages:

[0029] (1) The ZSM-22 molecular sieve provided by the present invention has a small number and proportion of strong B acid sites on the outer surface and pores of the molecular sieve. Furthermore, the outer surface and pores are rich in B acid sites. When applied to the hydroisomerization reaction process, it can significantly improve the yield and quality of the target product.

[0030] (2) In the preparation method of ZSM-22 molecular sieve provided by the present invention, firstly, a mixture of silicon source, template agent 1 and water undergoes a crystallization reaction to generate hydroxyl-rich molecular sieve primary structural unit silicon-oxygen tetrahedron and secondary structural unit. Then, hydrophobic long-chain aliphatic amine molecules are combined with the hydroxyl groups on the surface of the structural unit through hydrogen bonds and arranged in an orderly and uniformly dispersed manner. Under the action of alkali, they dissociate into uniform structural segments with specific channels. Then, with the assistance of ZSM-22 seed crystals, they are rapidly assembled into metastable ZSM-22 nanocrystals of pure silicon. Afterward, aluminum species and template agent 1 combine to form a chelate, which combines with the hydroxyl groups at specific sites on the surface of metastable ZSM-22 nanocrystals. During the high-temperature crystallization process, the chelate is embedded in the framework structure and grows into a ZSM-22 molecular sieve with a small number and proportion of strong B acid sites on the outer surface and pores, but a large number and proportion of B acid sites. Attached Figure Description

[0031] Figure 1 The image shows the XRD pattern of the synthesized product in Example 1 of this invention. Detailed Implementation

[0032] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0033] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] In this invention, "total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy" is used to represent the amount of Brønsted acid distributed on the pores and outer surface of ZSM-22 molecular sieves, and "the amount of Brønsted acid with a desorption temperature >420℃ in 2,6-dimethylpyridine infrared spectroscopy" is used to represent the amount of strong Brønsted acid distributed on the outer surface and pores of ZSM-22 molecular sieves. The determination is performed using 2,6-dimethylpyridine adsorption infrared spectroscopy. The specific process involves preparing the molecular sieve sample into a self-supporting wafer (5-6 mg / cm³). 2 The sample was placed in an in-situ cell and treated under vacuum at 400℃ for 4 hours, then cooled to 50℃, and spectra were collected. After adsorbing 2,6-dimethylpyridine for 10 minutes, the sample was heated to 150℃ for desorption for 1 hour, cooled to room temperature, and spectra were collected to calculate the total Brønsted acid content of 2,6-dimethylpyridine in the infrared spectrum. The sample was then heated to 420℃ for desorption for 1 hour, cooled to room temperature, and spectra were collected to calculate the Brønsted acid content of 2,6-dimethylpyridine in the infrared spectrum where the desorption temperature was >420℃. The Brønsted acid content was calculated according to the Lambert-Beer law, using a 1630 cm⁻¹ spectral density. -1 1650cm -1 The amount of Brønsted acid is calculated by measuring the area of ​​the absorption peak.

[0035] In this invention, "total Brønsted acid content in pyridine infrared spectroscopy" is used to represent the total Brønsted acid content in ZSM-22 molecular sieves, including Brønsted acid on the outer surface of the molecular sieve, at the pore openings, and within the pores. It is determined by pyridine adsorption infrared spectroscopy. The specific process is as follows: ZSM-22 molecular sieve samples are prepared into self-supporting wafers (5-6 mg / cm³). 2 The sample was placed in an in-situ cell and treated under vacuum at 400℃ for 4 hours, then cooled to 50℃, and spectra were collected. After adsorbing pyridine for 10 minutes, the sample was heated to 150℃ for desorption for 1 hour, cooled to room temperature, and spectra were collected. The total Brønsted acid content of pyridine was calculated. The Brønsted acid content was calculated according to the Lambert-Beer law, using a 1540 cm⁻¹ spectral depth. -1 The amount of Brønsted acid is calculated by measuring the area of ​​the absorption peak.

[0036] Example 1

[0037] 4.68 g of hexamethylenediamine was weighed, and then deionized water and fumed silica (calculated as SiO2) were added sequentially according to a molar ratio of 30:0.4:1. The mixture was stirred at room temperature (25°C) for 1 hour, and then transferred to a 100 mL reactor lined with polytetrafluoroethylene for crystallization at 150°C for 24 hours. The reacted material was centrifuged to obtain 6.59 g of solid material.

[0038] Add 10 mL of oleylamine to the solid material, mix thoroughly in a shaker, and stir at 25°C for 0.5 h at a stirring rate of 200 rpm. Then add 42 mL of 0.008 mol / L NaOH solution, and perform a low-temperature treatment under stirring conditions: temperature 25°C, time 6 h, stirring rate 200 rpm, to obtain a mixed solution. Disperse 0.16 g of ZSM-22 seed crystals in 20 mL of deionized water, and add the obtained ZSM-22 seed crystal solution to the above mixed solution for a second low-temperature treatment: temperature 80°C, time 16 h, stirring rate 200 rpm, to obtain a mixed material.

[0039] 0.67 g of Al2(SO4)3·18H2O and 0.32 g of ethylenediamine were dissolved in 20 mL of deionized water, then mixed with the above mixture, and transferred to a 150 mL reactor lined with polytetrafluoroethylene. Dynamic crystallization was carried out at 180 °C for 48 h at a rotation speed of 40 rpm. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and calcined at 550 °C for 4 h to obtain the final ZSM-22 molecular sieve, named Z-1.

[0040] The total Brønsted acid content of Z-1 molecular sieve pyridine infrared spectroscopy is 0.235 mmol / g, and the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 0.201 mmol / g. The ratio of the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy to the total Brønsted acid content of pyridine infrared spectroscopy is 85.5:100. Among the Brønsted acid in 2,6-dimethylpyridine infrared spectroscopy, the Brønsted acid content with a desorption temperature >420℃ is 0.006 mmol / g, and the ratio of the Brønsted acid content with a desorption temperature >420℃ to the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 3:100.

[0041] Example 2

[0042] 5.81 g of hexamethylenediamine was weighed, and then deionized water and fumed silica (calculated as SiO2) were added sequentially according to a molar ratio of deionized water, hexamethylenediamine, and fumed silica (calculated as SiO2) of 70:0.5:1. The mixture was stirred at room temperature (25°C) for 1 hour, then transferred to a 100 mL reactor lined with polytetrafluoroethylene (PTFE) for crystallization at 150°C for 24 hours. The reacted material was centrifuged to obtain 6.63 g of solid material.

[0043] Add 8 mL of oleylamine to the solid material, mix thoroughly in a shaker, and stir at 25°C for 0.5 h at a stirring rate of 200 rpm. Then add 42 mL of 0.01 mol / L NaOH solution and perform a low-temperature treatment under stirring conditions: temperature 25°C, time 6 h, stirring rate 200 rpm, to obtain a mixed solution. Add 0.16 g of ZSM-22 seed crystals to 20 mL of deionized water and disperse evenly. Add the obtained ZSM-22 seed crystal solution to the above mixed solution and perform a second low-temperature treatment: temperature 80°C, time 16 h, stirring rate 200 rpm, to obtain a mixed material.

[0044] 0.83 g of Al2(SO4)3·18H2O and 0.32 g of ethylenediamine were dissolved in 20 mL of deionized water, then mixed with the above mixture, and transferred to a 150 mL reactor lined with polytetrafluoroethylene. Dynamic crystallization was carried out at 180 °C for 48 h at a rotation speed of 40 rpm. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and calcined at 550 °C for 4 h to obtain the final ZSM-22 molecular sieve, named Z-2.

[0045] The total Brønsted acid content of Z-2 molecular sieve pyridine infrared spectroscopy is 0.402 mmol / g, and the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 0.323 mmol / g. The ratio of the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy to the total Brønsted acid content of pyridine infrared spectroscopy is 80.4:100. Among the Brønsted acid in 2,6-dimethylpyridine infrared spectroscopy, the Brønsted acid content with a desorption temperature >420℃ is 0.035 mmol / g, and the ratio of the Brønsted acid content with a desorption temperature >420℃ to the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 11:100.

[0046] Example 3

[0047] 4.68 g of hexamethylenediamine was weighed, and then deionized water and fumed silica (calculated as SiO2) were added sequentially according to a molar ratio of deionized water, hexamethylenediamine, and fumed silica (calculated as SiO2) of 40:0.4:1. The mixture was stirred at room temperature (30°C) for 1 hour, then transferred to a 100 mL reactor lined with polytetrafluoroethylene (PTFE) for crystallization at 180°C for 24 hours. The reacted material was centrifuged to obtain 6.60 g of solid material.

[0048] Add 3.6 mL of oleylamine to the solid material, mix thoroughly in a shaker, and stir at 25°C for 0.5 h at a stirring rate of 200 rpm. Then add 42 mL of 0.008 mol / L NaOH solution, and perform a low-temperature treatment under stirring conditions: temperature 20°C, time 3 h, stirring rate 200 rpm, to obtain a mixed solution. Add 0.03 g of ZSM-22 seed crystals to 20 mL of deionized water and disperse evenly. Add the obtained ZSM-22 seed crystal solution to the above mixed solution and perform a second low-temperature treatment: temperature 60°C, time 30 h, stirring rate 200 rpm, to obtain a mixed material.

[0049] 0.67 g of Al2(SO4)3·18H2O and 0.32 g of ethylenediamine were dissolved in 20 mL of deionized water, then mixed with the above mixture, and transferred to a 150 mL reactor lined with polytetrafluoroethylene. Dynamic crystallization was carried out at 200 °C for 48 h at a rotation speed of 40 rpm. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and calcined at 550 °C for 4 h to obtain the final ZSM-22 molecular sieve, named Z-3.

[0050] The total Brønsted acid content of Z-3 molecular sieve pyridine infrared spectroscopy is 0.228 mmol / g, and the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 0.166 mmol / g. The ratio of the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy to the total Brønsted acid content of pyridine infrared spectroscopy is 72.8:100. Among the Brønsted acid in 2,6-dimethylpyridine infrared spectroscopy, the Brønsted acid content with a desorption temperature >420℃ is 0.033 mmol / g, and the ratio of the Brønsted acid content with a desorption temperature >420℃ to the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 19.9:100.

[0051] Example 4

[0052] 4.68 g of hexamethylenediamine was weighed, and then deionized water and fumed silica (calculated as SiO2) were added sequentially according to a molar ratio of deionized water, hexamethylenediamine, and fumed silica (calculated as SiO2) of 45:0.4:1. The mixture was stirred at room temperature (25°C) for 1 hour, then transferred to a 100 mL reactor lined with polytetrafluoroethylene (PTFE) for crystallization at 200°C for 12 hours. The reacted material was centrifuged to obtain 6.72 g of solid material.

[0053] Add 10 mL of oleylamine to the solid material, mix thoroughly in a shaker, and stir at 25°C for 0.5 h at a stirring rate of 200 rpm. Then add 42 mL of 0.006 mol / L NaOH solution, and perform a low-temperature treatment under stirring conditions: temperature 20°C, time 12 h, stirring rate 200 rpm, to obtain a mixed solution. Disperse 0.33 g of ZSM-22 seed crystals in 20 mL of deionized water, and add the obtained ZSM-22 seed crystal solution to the above mixed solution for a second low-temperature treatment: temperature 120°C, time 20 h, stirring rate 200 rpm, to obtain a mixed material.

[0054] 0.99 g of Al2(SO4)3·18H2O and 0.26 g of ethylenediamine were dissolved in 20 mL of deionized water, then mixed with the above mixture, and transferred to a 150 mL reactor lined with polytetrafluoroethylene. Dynamic crystallization was carried out at 180 °C for 48 h at a rotation speed of 40 rpm. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and calcined at 550 °C for 4 h to obtain the final ZSM-22 molecular sieve, named Z-4. The total Brønsted acid content of Z-4 molecular sieve pyridine infrared spectroscopy is 0.513 mmol / g, and the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 0.420 mmol / g. The ratio of the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy to the total Brønsted acid content of pyridine infrared spectroscopy is 82:100. Among the Brønsted acid in 2,6-dimethylpyridine infrared spectroscopy, the Brønsted acid content with a desorption temperature >420℃ is 0.061 mmol / g, and the ratio of the Brønsted acid content with a desorption temperature >420℃ to the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 14.7:100.

[0055] Example 5

[0056] ZSM-22 molecular sieve was prepared according to the method in Example 1, except that the same weight of undecylamine was used instead of oleylamine to obtain ZSM-22 molecular sieve, which was named Z-5.

[0057] The total Brønsted acid content of Z-5 molecular sieve pyridine infrared spectroscopy is 0.213 mmol / g, and the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 0.162 mmol / g. The ratio of the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy to the total Brønsted acid content of pyridine infrared spectroscopy is 76.4:100. Among the Brønsted acid in 2,6-dimethylpyridine infrared spectroscopy, the Brønsted acid content with a desorption temperature >420℃ is 0.021 mmol / g, and the ratio of the Brønsted acid content with a desorption temperature >420℃ to the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 12.8:100.

[0058] Comparative Example 1

[0059] ZSM-22 molecular sieve was prepared according to the method in Example 1, except that oleylamine was not added during the preparation process, and ZSM-22 molecular sieve DZ-1 was obtained.

[0060] The total Brønsted acid content of pyridine infrared spectroscopy in DZ-1 molecular sieve is 0.241 mmol / g, and the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 0.121 mmol / g. The ratio of the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy to the total Brønsted acid content of pyridine infrared spectroscopy is 50.3:100. Among the Brønsted acid in 2,6-dimethylpyridine infrared spectroscopy, the Brønsted acid content with a desorption temperature >420℃ is 0.049 mmol / g, and the ratio of the Brønsted acid content with a desorption temperature >420℃ to the total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy is 40.7:100.

[0061] Application Examples 1-5 and Comparative Example 1: Using the ZSM-22 molecular sieve samples prepared in Examples 1-5 and Comparative Example 1 as carriers, catalyst powders were prepared by loading 0.5 wt.% of noble metal Pt using the impregnation method.

[0062] The performance of ZSM-22 molecular sieve samples was evaluated in a fixed-bed microreactor: Catalyst powder was compressed into tablets and pulverized into 5-10 mesh particles, which were then loaded into the fixed-bed microreactor. The hydrogenation of ethylcyclohexane was used as a model reaction, with a mixture of 90 wt.% decahydronaphthalene and 10 wt.% ethylcyclohexane as the reactants. The reaction temperature was 300℃, and the liquid hourly space velocity was 1.0 h⁻¹. -1 The hydrogen-to-oil volume ratio was 600, and the reaction pressure was 6.0 MPa. The catalytic results are shown in Table 1.

[0063] Table 1 Catalytic Results

[0064]

[0065] As can be seen from the results in Table 1 above, when the hydrogenation catalyst using the ZSM-22 molecular sieve of the present invention as a support is applied to the hydroisomerization reaction process, it can significantly improve the yield and quality of the target product.

Claims

1. A ZSM-22 molecular sieve, characterized in that: The ZSM-22 molecular sieve has a total Brønsted acid content of 2,6-dimethylpyridine infrared spectroscopy of 0.07~0.51 mmol / g, preferably 0.08~0.49 mmol / g; among the Brønsted acid of 2,6-dimethylpyridine infrared spectroscopy, the amount of Brønsted acid with a desorption temperature >420℃ is 0~0.12 mmol / g, preferably 0.01~0.10 mmol / g; preferably, the ratio of the amount of Brønsted acid with a desorption temperature >420℃ to the amount of total Brønsted acid of 2,6-dimethylpyridine infrared spectroscopy is 0~22:100, more preferably 2~20:

100.

2. The molecular sieve according to claim 1, characterized in that: The total β-carboxylic acid content of the molecular sieve in infrared spectroscopy is 0.10~0.54 mmol / g, preferably 0.12~0.52 mmol / g; preferably, the ratio of the total β-carboxylic acid content of 2,6-dimethylpyridine in infrared spectroscopy to the total β-carboxylic acid content of pyridine in infrared spectroscopy in the ZSM-22 molecular sieve is 67~95:100, preferably 70~93:

100.

3. A method for preparing ZSM-22 molecular sieve, characterized in that: The method includes the following: (1) A mixture of silicon source, template agent 1 and water is subjected to a crystallization reaction, and the solid phase material is separated from the reacted material; (2) The solid material obtained in step (1), the fatty amine and the inorganic base are mixed and subjected to a low temperature treatment, and then ZSM-22 seed crystals are added and subjected to a second low temperature treatment to obtain a mixture. (3) Mix the aluminum source, template agent 2 and the mixture obtained in step (2), and then crystallize, filter, wash, dry and calcine in sequence to obtain the final ZSM-22 molecular sieve.

4. The method according to claim 3, characterized in that: In step (1), the silicon source is one or more of silica, silica sol, water glass, fumed silica, and tetraethyl orthosilicate, preferably silica sol and / or fumed silica.

5. The method according to claim 3, characterized in that: In step (1), the template agent 1 is one or more of hexamethylenediamine, ethanol, and n-hexamethylenediamine, preferably hexamethylenediamine and / or ethanol.

6. The method according to claim 3, characterized in that: In step (1), the molar ratio of water, template agent 1 and silicon source (calculated as SiO2) is (20~80):(0.1~1):1, preferably (30~70):(0.15~0.8):

1.

7. The method according to claim 3, characterized in that: In step (1), the crystallization reaction conditions are as follows: the crystallization temperature is 120~220 ℃, the crystallization time is 8~48 h, and the preferred crystallization temperature is 140~200 ℃ and the crystallization time is 12~30 h.

8. The method according to claim 3, characterized in that: In step (2), the fatty amine is a C12-C18 fatty amine, preferably one or more of oleylamine, octadecylamine, and dodecylamine; the liquid-solid ratio of the fatty amine to the solid material obtained in step (1) is 0.3~3 mL / g, preferably 0.5~2.0 mL / g.

9. The method according to claim 3, characterized in that: In step (2), the inorganic base is any one of sodium hydroxide, potassium hydroxide, and ammonia water.

10. The method according to claim 3, characterized in that: In step (2), the inorganic alkali is used in the form of an alkaline solution with a concentration of 0.003~0.015 mol / L, preferably 0.005~0.010 mol / L; the liquid-solid ratio of the alkaline solution to the solid material obtained in step (1) is 2~20 mL / g, preferably 5~15 mL / g.

11. The method according to claim 3, characterized in that: In step (2), based on the weight of the solid material obtained in step (1), the amount of ZSM-22 seed crystals added is 0.1~8.0 wt%, preferably 0.5~5.0 wt%.

12. The method according to claim 3, characterized in that: In step (2), the temperature of the first low-temperature treatment is 20~40 ℃ and the time is 3~15 h; the temperature of the second low-temperature treatment is 60~120 ℃ and the time is 6~30 h; preferably, the temperature of the second low-temperature treatment is higher than the temperature of the first low-temperature treatment.

13. The method according to claim 3, characterized in that: In step (3), the aluminum source is one or more of aluminum sulfate, aluminum isopropoxide, sodium aluminate and aluminum hydroxide, preferably aluminum sulfate; the molar ratio of the aluminum source (calculated as Al2O3) to the solid material obtained in step (1) (calculated as SiO2) is 0.002~0.015, preferably 0.005~0.

01.

14. The method according to claim 3, characterized in that: In step (3), the template agent 2 is one or more of 1,6-hexanediamine and ethylenediamine, preferably ethylenediamine; the molar ratio of the template agent 2 to the solid material (calculated as SiO2) obtained in step (1) is 0.05~0.25, preferably 0.08~0.

20.

15. The method according to claim 3, characterized in that: In step (3), the crystallization temperature is 180~220 ℃ and the crystallization time is 24~72 h.

16. The method according to claim 3, characterized in that: In step (3), the drying temperature is 80~120 ℃ and the drying time is 6~12 h; the calcination temperature is 540~560 ℃ and the calcination time is 3~8 h.

17. The application of the ZSM-22 molecular sieve according to any one of claims 1-2 in the hydroisomerization reaction process.

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