ZSM-23 molecular sieve, preparation method therefor, and catalyst comprising same

Abstract

Provided are a ZSM-23 molecular sieve, a preparation method therefor, and a catalyst comprising same. The preparation method comprises: mixing a silicon source, an aluminum source, an alkali source, an organic structure directing agent, a mesoporous template agent, a crystal growth inhibitor, and water, crystallizing, washing, drying, and roasting to obtain the ZSM-23 molecular sieve, wherein the crystal growth inhibitor comprises at least one of trimethoxy[3-(phenylamino)propyl]silane, sodium dodecyl sulfate, tetradecylphosphoric acid, and glutamic acid. The method implements one-step synthesis of a ZSM-23 molecular sieve having a small crystal grain size and a hierarchical pore structure.

Description

ZSM-23 molecular sieve, its preparation method, and catalyst

[0001] This application claims priority to Chinese Patent Application No. 202411548164.8, filed on October 31, 2024, entitled "ZSM-23 molecular sieve and its preparation method and catalyst", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of lubricating oil hydrogenation catalysis technology, and in particular to a ZSM-23 molecular sieve, its preparation method, and catalyst. Background Technology

[0003] N-alkanes constitute a large proportion of petroleum fractions and Fischer-Tropsch synthetic oils. However, isoalkanes have several performance advantages over n-alkanes, thus the hydroisomerization of n-alkanes has received widespread attention in recent years. Specifically, the hydroisomerization of C4-C8 n-alkanes can significantly increase the octane number of gasoline, offsetting the reduction in octane number caused by strict controls on olefin and aromatic content. The hydroisomerization of C10-C22 alkanes can adjust the cold filter plugging point, viscosity, and pour point of diesel fuel, improving its low-temperature flow properties. N-alkanes with more than 20 carbon atoms are commonly referred to as waxes; hydroisomerization can be used as a dewaxing method for lubricating oils, producing lubricating oils with high viscosity and low pour point. Therefore, the hydroisomerization of n-alkanes is a technology with high economic benefits and environmental advantages.

[0004] ZSM-23 molecular sieves are one of the supports for preparing catalysts for the hydroisomerization reaction of n-alkanes. Currently, methods for synthesizing hierarchical ZSM-23 molecular sieves can be broadly categorized into in-situ synthesis, post-treatment, and micro / mesoporous molecular sieve composite methods. Post-treatment often uses alkali desilication; however, this mesoporous method can lead to the collapse of the molecular sieve crystal framework, significantly reducing the crystallinity, mechanical strength, and hydrothermal properties of the molecular sieve. In in-situ synthesis, using hard templates such as carbon materials or relatively heavy soft mesoporous templates such as starch or cellulose can cause coking during calcination and demolding, clogging the pores. The preparation process of composite molecular sieves is generally cumbersome, and it is difficult to control the pore and acid distribution.

[0005] CN107311202A discloses a method for synthesizing ZSM-22 / ZSM-23 composite molecular sieves with low template agent dosage. The ZSM-22 and ZSM-23 molecular sieves obtained by this method are both microporous structures. Therefore, the mesoporous structures involved are mainly stacked pores, which have poor regularity and stability.

[0006] CN116116456A discloses a method for preparing a modified Pt / ZSM-23 catalyst. This method requires the addition of seed crystals. However, the addition of seed crystals usually increases production costs and can easily produce white silica components in the product.

[0007] CN114715913A discloses a ZSM-23 molecular sieve and its preparation method. The silicon source used in this method requires pretreatment, which is not only cumbersome and difficult to control, but also generates a large amount of alkaline wastewater, which is not conducive to environmental protection.

[0008] CN107519924A discloses a method for preparing a composite material containing regular mesoporous Y / EU-1 / ZSM-23 / ZSM-5 / ASA. The synthesis of this composite molecular sieve is too complicated, and the pore dispersion and acidity control are difficult. Among them, the composite ZSM-5 molecular sieve is a three-dimensional porous molecular sieve. Bifunctional catalysts prepared with this composite molecular sieve support are more likely to cause the cracking of long-chain reaction intermediates.

[0009] Therefore, there is a need for a direct, simple, economical and efficient method for synthesizing hierarchical porous ZSM-23 molecular sieve supports. Summary of the Invention

[0010] To overcome the above problems, the present invention aims to provide a ZSM-23 molecular sieve, its preparation method, and a catalyst. The preparation method provided by the present invention, by employing modifiers such as crystal growth inhibitors, can simultaneously regulate the grain and pore structure of the molecular sieve, generating a small-grained, mesoporous ZSM-23 molecular sieve in one step.

[0011] To achieve the above objectives, the present invention provides a method for preparing ZSM-23 molecular sieve, the method comprising:

[0012] A raw material solution is formed by mixing silicon source, aluminum source, alkali source, organic structure directing agent, mesoporous template agent, crystal growth inhibitor, and water. The solution is then crystallized, washed, dried, and calcined to obtain the ZSM-23 molecular sieve.

[0013] The crystal growth inhibitor includes one or more of the following: trimethoxy[3-(phenylamino)propyl]silane, sodium dodecyl sulfate, tetradecyl phosphate, and glutamic acid.

[0014] This method prepares hierarchical porous ZSM-23 molecular sieves through in-situ synthesis. The added mesoporous template agent acts as a pore-forming agent. After the primary structure is formed during the crystallization induction period, the molecular dynamic radius of the pore-forming agent is larger than the main pore size, which disrupts the formation of micropores and promotes the formation of more mesopores. This, combined with the silicon and aluminum sources, forms a hierarchical porous structure. During the nucleation period, growth inhibitors adhere to the initial structure of the crystal nuclei, hindering the aggregation between nuclei and restricting growth along the main pore direction, which is beneficial for the formation of small-crystal ZSM-23 molecular sieves. Therefore, this method can synthesize hierarchical porous-small-crystal ZSM-23 molecular sieves in one step. The direct formation of small crystals with mesoporous and microporous structures during the synthesis of ZSM-23 molecular sieves facilitates product diffusion from the pores, improves reaction efficiency and isomer conversion rate, reduces cracking rate, and decreases the amount of ZSM-23 molecular sieve used in the catalyst.

[0015] In the above preparation method, the molar ratio of SiO2 to Al2O3 in the raw material solution can generally be 1:0.005-0.5, specifically 1:0.005, 1:0.01, 1:0.015, 1:0.02, 1:0.025, 1:0.03, 1:0.035, 1:0.04, 1:0.045, 1:0.05, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, etc., as well as a range with any two of the above specific values ​​as endpoints; further, it can be controlled to 1:0.008-0.3.

[0016] In the above preparation method, the OH in the raw material solution - The molar ratio of hydroxide ions to SiO2 can generally be 0.01-0.8:1, specifically 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, etc., as well as any two of the above specific values ​​as endpoints; it can be further controlled to 0.05-0.7:1.

[0017] In the above preparation method, the molar ratio of organic structure directing agent to SiO2 in the raw material solution can generally be 0.1-5:1, specifically 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 2:1, 3:1, 4:1, 5:1, etc., and a range with any two of the above specific values ​​as endpoints; further, it can be controlled to 0.4-3:1 or 0.1-3:1.

[0018] In the above preparation method, the molar ratio of mesoporous template agent to SiO2 in the raw material solution is generally 0.001-0.09:1, specifically 0.001:1, 0.002:1, 0.003:1, 0.004:1, 0.005:1, 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, etc., and a range with any two of the above specific values ​​as endpoints; further, it can be controlled to 0.003-0.09:1, and even further, it can be 0.003-0.07:1.

[0019] In the above preparation method, the molar ratio of crystal growth inhibitor to SiO2 in the raw material solution is generally 0.01-0.6:1, specifically 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, etc., and a range with any two of the above specific values ​​as endpoints; further, it can be controlled to 0.04-0.4:1 or 0.1-0.4:1.

[0020] In the above preparation method, the raw material solution generally satisfies the following molar ratio: H2O:SiO2 = 20-120:1, specifically it can be 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, 110:1, 120:1, etc., and the range with any two of the above specific values ​​as endpoints; further, it can be controlled to 30-101:1, and even further, it can be controlled to 30-100:1.

[0021] In the above preparation method, the raw material solution satisfies the following molar ratio: SiO2:Al2O3:OH - Organic structure guiding agent: mesoporous template agent: crystal growth inhibitor: H2O = 1: 0.005-0.5: 0.01-0.8: 0.1-5: 0.001-0.09: 0.01-0.6: 20-120; further, the following molar ratio can be satisfied: SiO2: Al2O3: OH - Organic structure guiding agent: mesoporous template agent: crystal growth inhibitor: H2O = 1: 0.008-0.3: 0.05-0.7: 0.4-3: 0.003-0.07: 0.04-0.4: 30-100.

[0022] In the above preparation method, the crystal growth inhibitor can reduce the crystal size of ZSM-23 molecular sieve, thereby shortening the diffusion distance of reaction intermediates in ZSM-23 molecular sieve and reducing the cracking probability. The crystal growth inhibitor may include one or more of trimethoxy[3-(phenylamino)propyl]silane, sodium dodecyl sulfate, tetradecyl phosphoric acid, glutamic acid, etc. Glutamic acid is acidic in solution; sodium dodecyl sulfate and trimethoxy[3-(phenylamino)propyl]silane have long molecular chains; tetradecyl phosphoric acid is both acidic in solution and has a long molecular chain. In some specific embodiments, tetradecyl phosphoric acid has a better crystal growth inhibition effect than trimethoxy[3-(phenylamino)propyl]silane, sodium dodecyl sulfate, glutamic acid, etc.

[0023] In the above preparation method, the mesoporous template agent can introduce a mesoporous structure into the ZSM-23 molecular sieve, giving the ZSM-23 molecular sieve a hierarchical porous structure, improving the diffusion efficiency of reaction intermediates in the ZSM-23 molecular sieve, thereby increasing the isomerization conversion rate and reducing the cracking rate. The mesoporous template agent can be a soft mesoporous template agent, specifically including one or more of L-lysine, hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride. L-lysine not only has a solution acidity / alkalinity similar to that of hexadecyltrimethylammonium bromide, but also can ionize in solution, exhibiting better pore-forming effect than hexadecyltrimethylammonium bromide. Sodium dodecylbenzenesulfonate and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride also have good pore-forming effects. The above-mentioned mesoporous template agent has good water or alcohol solubility and can be removed by dissolving in water or alcohol during the washing process of ZSM-23 molecular sieve.

[0024] This invention synthesizes hierarchical ZSM-23 molecular sieves through a one-step hydrothermal synthesis by adding a suitable soft mesoporous template agent. This method is direct, simple, economical, and effective. In the above method, the crystal growth inhibitor and the mesoporous template agent can be synergistically combined to improve the mesoporous structure and catalytic performance of the ZSM-23 molecular sieve. The combination of the crystal growth inhibitor and the mesoporous template agent includes, but is not limited to, at least one of trimethoxy[3-(phenylamino)propyl]silane, sodium dodecyl sulfate, tetradecyl phosphate, and glutamic acid, combined with at least one of L-lysine, hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride.

[0025] In some specific embodiments, the combination of the crystal growth inhibitor and the mesoporous template agent may include, but is not limited to, the following: a combination of L-lysine and trimethoxy[3-(phenylamino)propyl]silane, a combination of L-lysine and tetradecyl phosphate, a combination of L-lysine and glutamic acid, a combination of L-lysine and sodium dodecyl sulfate, a combination of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride and trimethoxy[3-(phenylamino)propyl]silane, a combination of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride and tetradecyl phosphate, and a combination of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride and... Combinations of glutamic acid, dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride and sodium dodecyl sulfate, sodium dodecylbenzenesulfonate and trimethoxy[3-(phenylamino)propyl]silane, sodium dodecylbenzenesulfonate and tetradecyl phosphoric acid, sodium dodecylbenzenesulfonate and glutamic acid, sodium dodecylbenzenesulfonate and sodium dodecyl sulfate, hexadecyltrimethylammonium bromide and trimethoxy[3-(phenylamino)propyl]silane, hexadecyltrimethylammonium bromide and tetradecyl phosphoric acid, hexadecyltrimethylammonium bromide and glutamic acid, hexadecyltrimethylammonium bromide and sodium dodecyl sulfate, etc.

[0026] In some specific embodiments, the combination of the crystal growth inhibitor and the mesoporous template agent may include at least one of the following combinations: a combination of hexadecyltrimethylammonium bromide and glutamic acid, a combination of L-lysine and trimethoxy[3-(phenylamino)propyl]silane, a combination of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride and sodium dodecyl sulfate, and a combination of sodium dodecylbenzenesulfonate and tetradecyl phosphate.

[0027] In the above preparation method, the silicon source may include one or more of tetraethyl orthosilicate, silica sol, sodium silicate, and silica fume.

[0028] In the above preparation method, the aluminum source may include one or more of the following: sodium aluminate, boehmite (e.g., boehmite NB-01, which can be purchased from Sinopharm Group), aluminum isopropoxide, and aluminum sulfate.

[0029] In the above preparation method, the organic structure directing agent may include one or more of pyrrolidine, isopropylamine, ethylene glycol, N,N-dimethylformamide, etc.

[0030] In the above preparation method, the alkali source may include one or a combination of two or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, barium hydroxide, and ammonia.

[0031] In the above preparation method, the crystallization temperature can be controlled between 120-200℃, for example, specific values ​​such as 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, and any two of the above specific values ​​as endpoints; the crystallization time can be controlled between 24h-120h, for example, specific values ​​such as 24h, 36h, 48h, 60h, 72h, 84h, 96h, 108h, 120h, and any two of the above specific values ​​as endpoints.

[0032] In the above preparation method, the calcination temperature is 550℃-580℃, for example, specific values ​​such as 550℃, 555℃, 560℃, 565℃, 570℃, 575℃, 580℃, and any two of the above specific values ​​as endpoints; the calcination time is 6-8 hours, for example, specific values ​​such as 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, and any two of the above specific values ​​as endpoints.

[0033] This invention also provides a ZSM-23 molecular sieve, which is obtained by the above-described preparation method. Compared with conventional ZSM-23 molecular sieves, the ZSM-23 molecular sieve provided by this invention has smaller crystallites, a richer mesoporous structure, and a hierarchical pore structure.

[0034] In some specific embodiments, the particle size of the ZSM-23 molecular sieve can be 0.08μm-1μm, for example, it can be specific values ​​such as 0.08μm, 0.09μm, 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, etc., and a range with any two of the above specific values ​​as endpoints; further, it can be 0.3-1μm or 0.08-0.13μm.

[0035] In some specific embodiments, the average particle size of the ZSM-23 molecular sieve along its a-axis can be 0.08-1 μm, for example, specific values ​​such as 0.08 μm, 0.09 μm, 0.1 μm, 0.11 μm, 0.12 μm, 0.13 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 0.93 μm, 1 μm, etc., and a range with any two of the above specific values ​​as endpoints; further, it can be 0.08-0.13 μm.

[0036] In some specific embodiments, the average particle size of the ZSM-23 molecular sieve in directions other than the a-axis can be 0.09-0.1 μm, for example, it can be specific values ​​such as 0.09 μm, 0.091 μm, 0.092 μm, 0.093 μm, 0.094 μm, 0.095 μm, 0.096 μm, 0.097 μm, 0.098 μm, 0.099 μm, 0.1 μm, etc., as well as a range with any two of the above specific values ​​as endpoints.

[0037] In some specific embodiments, the total pore volume of the ZSM-23 molecular sieve is 0.32 cm³. 3 / g-0.4cm 3 / g, for example, can be 0.32cm 3 / g, 0.33cm 3 / g, 0.34cm 3 / g, 0.35cm 3 / g, 0.36cm 3 / g, 0.37cm 3 / g, 0.38cm 3 / g, 0.39cm 3 / g, 0.4cm 3 The specific values ​​such as / g and the range with any two of the above specific values ​​as endpoints.

[0038] In some specific embodiments, the mesopore volume of the ZSM-23 molecular sieve is 0.19 cm³. 3 / g-0.32cm 3 / g, for example, can be 0.19cm 3 / g, 0.20cm 3 / g, 0.21cm 3 / g, 0.22cm 3 / g, 0.23cm 3 / g, 0.24cm 3 / g, 0.25cm 3 / g, 0.26cm 3 / g, 0.27cm 3 / g, 0.28cm 3 / g, 0.29cm 3 / g, 0.3cm 3 / g, 0.31cm 3 / g, 0.32cm 3 Specific values ​​such as / g and a range with any two of the above specific values ​​as endpoints; further, it can be 0.24cm. 3 / g-0.32cm 3 / g.

[0039] In some specific embodiments, the micropore volume of the ZSM-23 molecular sieve is 0.07-0.2 cm³. 3 / g, for example, 0.07cm 3 / g, 0.073cm 3 / g, 0.08cm 3 / g, 0.09cm 3 / g, 0.10cm 3 / g, 0.11cm 3 / g, 0.12cm 3 / g, 0.13cm 3 / g, 0.14cm 3 / g, 0.15cm 3 / g, 0.16cm 3 / g, 0.17cm 3 / g, 0.18cm 3 / g, 0.19cm 3 / g, 0.2cm 3 The specific values ​​such as / g and the range with any two of the above specific values ​​as endpoints.

[0040] The present invention also provides a catalyst made from the aforementioned ZSM-23 molecular sieve. In some specific embodiments, the catalyst can be used in the hydroisomerization reaction of n-alkanes, for example, it is suitable for the hydroisomerization reaction of n-alkanes having 4 or more carbon atoms.

[0041] The beneficial effects of this invention are as follows:

[0042] 1. This invention uses specific types of modifiers (crystal growth inhibitors, mesoporous template agents, etc.) to generate ZSM-23 molecular sieves with hierarchical pores (at least including mesopores and micropores) with small crystals in one step. Compared with existing methods for synthesizing ZSM-23 molecular sieves, the method of this invention can simultaneously regulate the crystal structure and pore structure.

[0043] 2. The ZSM-23 molecular sieve provided by this invention has a hierarchical porous structure, which improves the diffusion efficiency of reaction intermediates on bifunctional catalysts, reduces cracking rate, and increases yield.

[0044] 3. Compared with conventional ZSM-23 molecular sieves, the ZSM-23 molecular sieve of the present invention has a smaller crystal size, which can shorten the diffusion distance of reaction intermediates on the catalyst and further reduce the cracking probability.

[0045] 4. The modification of one-dimensional ZSM-23 molecular sieve can be applied to the preparation of high-quality Group III lubricating oil base oil with low turbidity point and high viscosity index using FT synthetic oil as raw material, and can also be applied to the preparation of aviation kerosene. Attached Figure Description

[0046] Figure 1 shows the XRD patterns of ZSM-23 molecular sieves from Examples 1 to 4.

[0047] Figure 2 shows the SEM image and particle size distribution along the a-axis of the ZSM-23 molecular sieve from Example 1.

[0048] Figure 3 shows the SEM image and particle size distribution along the a-axis of the ZSM-23 molecular sieve of Comparative Example 3.

[0049] Figure 4 shows the SEM image and particle size distribution along the a-axis of the ZSM-23 molecular sieve in Comparative Example 1.

[0050] Figure 5 shows the SEM image and particle size distribution along the a-axis of the ZSM-23 molecular sieve in Example 2.

[0051] Figure 6 shows the particle size distribution of the ZSM-23 molecular sieve in Example 1, excluding the a-axis.

[0052] Figure 7 shows the particle size distribution of ZSM-23 molecular sieve in Comparative Example 3, excluding the a-axis.

[0053] Figure 8 shows the particle size distribution of ZSM-23 molecular sieve in Comparative Example 1, excluding the a-axis.

[0054] Figure 9 shows the particle size distribution of the ZSM-23 molecular sieve in Example 2, excluding the a-axis. Detailed Implementation

[0055] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0056] In the following experiments, the average particle size of the molecular sieve was obtained by selecting 50 particle sizes in a scanning electron microscope and calculating the average value according to their distribution.

[0057] Example 1

[0058] This embodiment provides a ZSM-23 molecular sieve, the preparation method of which includes:

[0059] A raw material solution was prepared by uniformly mixing 6.5623 g of tetraethyl orthosilicate, 0.0409 g of boehmite, 0.4872 g of sodium hydroxide, 6.7216 g of pyrrolidine, 0.0344 g of cetyltrimethylammonium bromide, 1.0197 g of glutamic acid, and 56.169 g of water. The solution was crystallized at 120 °C for 72 h, washed, dried, and calcined at 550 °C for 6 h to obtain ZSM-23 molecular sieve.

[0060] The raw material solution satisfies the following molar ratio: SiO2:Al2O3 = 120; OH -SiO2 = 0.38; IPA (organic structure directing agent): SiO2 = 2.99; mesoporous template agent: SiO2 = 0.003; crystal growth inhibitor: SiO2 = 0.22; H2O: SiO2 = 99.99.

[0061] Figure 1 shows the XRD pattern of the ZSM-23 molecular sieve of this embodiment. XRD testing confirmed that the molecular sieve in this embodiment is ZSM-23. Figure 2 shows the SEM image and particle size distribution along the a-axis of the ZSM-23 molecular sieve of this embodiment. The grain size of the ZSM-23 molecular sieve is shown in Figure 2. The ZSM-23 molecular sieve grows along the a-axis, with an average particle size of 0.08 micrometers along the a-axis. Figure 6 shows the particle size distribution of the ZSM-23 molecular sieve in directions other than the a-axis, with an average particle size of 0.095 micrometers.

[0062] Example 2

[0063] This embodiment provides a ZSM-23 molecular sieve, the preparation method of which includes:

[0064] 29.4611g of silica sol, 5.4199g of aluminum isopropoxide, 0.1280g of potassium hydroxide, 4.6669g of ethylene glycol, 0.5535g of L-lysine, 1.5666g of trimethoxy[3-(phenylamino)propyl]silane, and 30.3240g of water were uniformly mixed to form a raw material solution. The solution was crystallized at 200℃ for 24h, washed, dried, and calcined at 550℃ for 6h to obtain ZSM-23 molecular sieve.

[0065] The raw material solution satisfies the following molar ratio: SiO2:Al2O3 = 3.34; OH - SiO2 = 0.0516; Organic structure directing agent: SiO2 = 1.754; Mesoporous template agent: SiO2 = 0.090; Crystal growth inhibitor: SiO2 = 0.143; H2O: SiO2 = 39.687.

[0066] Figure 1 shows the XRD pattern of the molecular sieve of this embodiment, which is ZSM-23 molecular sieve. Figure 5 shows the SEM image and particle size distribution along the a-axis of the ZSM-23 molecular sieve of this embodiment. As shown in Figure 5, the average particle size of the ZSM-23 molecular sieve along the a-axis is 0.93 micrometers. Figure 9 shows the particle size distribution of the ZSM-23 molecular sieve in directions other than the a-axis, with an average particle size of 0.095 micrometers.

[0067] Example 3

[0068] This embodiment provides a ZSM-23 molecular sieve, the preparation method of which includes:

[0069] 19.0633g sodium metasilicate nonahydrate, 6.8146g aluminum sulfate isooctadecyl sulfate, 7.4061g barium hydroxide, 1.5700g isopropylamine, 1.9846g dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, 8.4253g sodium dodecyl sulfate, and 258.47g water were uniformly mixed to form a raw material solution. The solution was crystallized at 160℃ for 120h, washed, dried, and calcined at 550℃ for 6h to obtain ZSM-23 molecular sieve.

[0070] The raw material solution satisfies the following molar ratio: SiO2:Al2O3 = 31.0429; OH - SiO2 = 0.528; Organic structure directing agent: SiO2 = 0.167; Mesoporous template agent: SiO2 = 0.0257; Crystal growth inhibitor: SiO2 = 0.184; H2O: SiO2 = 91.360.

[0071] Figure 1 shows the XRD pattern of the ZSM-23 molecular sieve of this embodiment. XRD testing confirmed that the molecular sieve of this embodiment is ZSM-23. Measurements showed that the average particle size along the a-axis of the ZSM-23 molecular sieve of this embodiment is 0.08 micrometers. The average particle size of the ZSM-23 molecular sieve in directions other than the a-axis is 0.093 micrometers.

[0072] Example 4

[0073] This embodiment provides a ZSM-23 molecular sieve, the preparation method of which includes:

[0074] 2.1145g of silica, 0.04662g of sodium aluminate, 0.043g of lithium hydroxide, 4.3948g of N,N-dimethylformamide, 0.4712g of sodium dodecylbenzenesulfonate, 3.9986g of tetradecyl phosphoric acid, and 63.4010g of water were uniformly mixed to form a raw material solution. The solution was crystallized at 120℃ for 24h, washed, dried, and calcined at 550℃ for 6h to obtain ZSM-23 molecular sieve.

[0075] The raw material solution satisfies the following molar ratio: SiO2:Al2O3 = 123.76; OH - SiO2 = 0.098; Organic structure directing agent: SiO2 = 0.708; Mesoporous template agent: SiO2 = 0.0391; Crystal growth inhibitor: SiO2 = 0.408; H2O: SiO2 = 101.034.

[0076] Figure 1 shows the XRD pattern of the ZSM-23 molecular sieve of this embodiment. XRD testing confirmed that the molecular sieve in this embodiment is ZSM-23. The average particle size along the a-axis of the ZSM-23 molecular sieve was measured to be 0.13 micrometers. The average particle size along other directions of the ZSM-23 molecular sieve, excluding the a-axis, was 0.096 micrometers.

[0077] Comparative Example 1

[0078] This comparative example provides a ZSM-23 molecular sieve, the preparation method of which includes:

[0079] 29.4611g of silica sol, 5.4199g of aluminum isopropoxide, 0.1280g of potassium hydroxide, 4.6669g of ethylene glycol, 1.5666g of trimethoxy[3-(phenylamino)propyl]silane, and 30.3240g of water were uniformly mixed to form a raw material solution. The solution was crystallized at 200℃ for 24h, washed, dried, and calcined at 550℃ for 6h to obtain ZSM-23 molecular sieve.

[0080] The raw material solution satisfies the following molar ratio: SiO2:Al2O3 = 3.34; OH - : SiO2 = 0.0516; Organic structure directing agent: SiO2 = 1.754; Crystal growth inhibitor: SiO2 = 0.143; H2O: SiO2 = 39.687.

[0081] Figure 4 shows the SEM image and particle size distribution along the a-axis of the ZSM-23 molecular sieve in this comparative example. As shown in Figure 4, the average particle size along the a-axis of the ZSM-23 molecular sieve is 1.15 μm. Figure 8 shows the particle size distribution of the ZSM-23 molecular sieve in directions other than the a-axis, with an average particle size of 0.094 μm.

[0082] Comparative Example 2

[0083] This comparative example provides a ZSM-23 molecular sieve, the preparation method of which includes:

[0084] 29.4611g of silica sol, 5.4199g of aluminum isopropoxide, 0.1280g of potassium hydroxide, 4.6669g of ethylene glycol, 0.5535g of L-lysine, and 30.3240g of water were uniformly mixed to form a raw material solution, which was crystallized at 200℃ for 24h, washed, dried, and calcined at 550℃ for 6h.

[0085] The raw material solution satisfies the following molar ratio: SiO2:Al2O3 = 3.34; OH -The BET test results are shown in Table 1. As can be seen from Table 1, the addition of L-lysine alone does indeed play a role in creating mesoporous structures.

[0086] Measurements showed that the average particle size of the ZSM-23 molecular sieve along the a-axis was 1.6 micrometers. The average particle size of the ZSM-23 molecular sieve in directions other than the a-axis was 0.090 micrometers.

[0087] Comparative Example 3

[0088] This comparative example provides a ZSM-23 molecular sieve, the preparation method of which includes:

[0089] 6.5623g of tetraethyl orthosilicate, 0.0409g of boehmite, 0.4872g of sodium hydroxide, 6.7216g of pyrrolidine, 0.0344g of cetyltrimethylammonium bromide, and 56.169g of water were uniformly mixed to form a raw material solution, which was then crystallized at 120℃ for 72h, washed, dried, and calcined at 550℃ for 6h.

[0090] The raw material solution satisfies the following molar ratio: SiO2:Al2O3 = 120; OH - SiO2 = 0.38; IPA: SiO2 = 2.99; Mesoporous template agent: SiO2 = 0.003; H2O: SiO2 = 99.99.

[0091] Figure 3 shows the SEM image and particle size distribution along the a-axis of the ZSM-23 molecular sieve in this comparative example. As shown in Figure 3, the average particle size along the a-axis of the ZSM-23 molecular sieve is 0.16 μm. Figure 7 shows the particle size distribution of the ZSM-23 molecular sieve in directions other than the a-axis, with an average particle size of 0.092 μm.

[0092] Comparative Example 4

[0093] This comparative example provides a ZSM-23 molecular sieve, the preparation method of which includes:

[0094] 2.1145g of silica, 0.04662g of sodium aluminate, 0.043g of lithium hydroxide, 4.3948g of N,N-dimethylformamide, and 63.4010g of water were uniformly mixed to form a raw material solution. The raw material solution was crystallized at 120℃ for 24h, washed, dried, and calcined at 550℃ for 6h.

[0095] The raw material solution has the following molar ratio: SiO2:Al2O3 = 123.76; OH -: SiO2 = 0.098; Organic structure directing agent: SiO2 = 0.708; H2O: SiO2 = 101.034.

[0096] Measurements showed that the average particle size of the ZSM-23 molecular sieve along the a-axis was 0.87 micrometers. The average particle size of the ZSM-23 molecular sieve along directions other than the a-axis was 0.093 micrometers.

[0097] Comparative Example 5

[0098] This comparative example provides a ZSM-23 molecular sieve, the preparation method of which includes:

[0099] 29.4611g of silica sol, 5.4199g of aluminum isopropoxide, 0.1280g of potassium hydroxide, 4.6669g of ethylene glycol, and 30.3240g of water were uniformly mixed to form a raw material solution, which was crystallized at 200℃ for 24h, washed, dried, and calcined at 550℃ for 6h to obtain ZSM-23 molecular sieve.

[0100] The raw material solution satisfies the following molar ratio: SiO2:Al2O3 = 3.34; OH - : SiO2 = 0.0516; Organic structure directing agent: SiO2 = 1.754; H2O: SiO2 = 39.687.

[0101] The average particle size of the ZSM-23 molecular sieve along the a-axis is 1.75 micrometers. The average particle size of the ZSM-23 molecular sieve in directions other than the a-axis is 0.098 micrometers.

[0102] Comparative Example 6

[0103] This comparative example provides a ZSM-23 molecular sieve, the preparation method of which includes:

[0104] 2.1145g of silica, 0.04662g of sodium aluminate, 0.043g of lithium hydroxide, 4.3948g of N,N-dimethylformamide, 0.4712g of sodium dodecylbenzenesulfonate, and 63.4010g of water were uniformly mixed to form a raw material solution. The solution was crystallized at 120℃ for 24h, washed, dried, and calcined at 550℃ for 6h to obtain ZSM-23 molecular sieve.

[0105] The raw material solution satisfies the following molar ratio: SiO2:Al2O3 = 123.76; OH - SiO2 = 0.098; Organic structure directing agent: SiO2 = 0.708; Mesoporous template agent: SiO2 = 0.0391; H2O: SiO2 = 101.034.

[0106] Measurements showed that the average particle size of the ZSM-23 molecular sieve along the a-axis was 0.80 micrometers. The average particle size of the ZSM-23 molecular sieve along directions other than the a-axis was 0.094 micrometers.

[0107] The BET test data and particle size distribution data of the ZSM-23 molecular sieves prepared in the above embodiments and comparative examples are summarized in Table 1.

[0108] Table 1

[0109] In the comparative examples above, Comparative Example 1 did not contain a mesoporous template agent compared to Example 2; Comparative Example 2 did not contain a crystal growth inhibitor compared to Example 2; Comparative Example 5 did not contain either a crystal growth inhibitor or a mesoporous template agent compared to Example 2; Comparative Example 3 did not contain a crystal growth inhibitor compared to Example 1; Comparative Example 4 did not contain either a crystal growth inhibitor or a mesoporous template agent compared to Example 4; and Comparative Example 6 did not contain a crystal growth inhibitor compared to Example 4.

[0110] As shown in Table 1, the total pore volume of Comparative Example 2 is significantly lower than that of Example 2, while the total pore volume of Comparative Examples 1 and 6 is significantly higher than that of Comparative Example 2, with a significant decrease in particle size along the a-axis. The mesopore volume of Comparative Example 2 is significantly lower than that of Example 2. The total pore volume and mesopore volume of Comparative Example 3 are significantly lower than those of Example 1, while the micropore volume is essentially the same. These results indicate that adding a mesoporous template agent is beneficial for increasing the mesopores in ZSM-23 molecular sieves, but it increases the size along the a-axis and reduces the overall specific surface area of ​​the ZSM-23 molecular sieve. Adding a crystal growth inhibitor can reduce the particle size along the a-axis, thereby increasing the specific surface area. Adding a crystal growth inhibitor to the mesoporous template agent can simultaneously increase both the mesopore volume and the total pore volume, constructing a small-crystal hierarchical porous structure.

[0111] The BET results of ZSM-23 molecular sieves in the examples and comparative examples in Table 1 were analyzed as follows:

[0112] (1) In Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 5:

[0113] Comparing Comparative Example 5 with Example 2, it can be seen that the mesopore volume of the ZSM-23 molecular sieve in Comparative Example 5 decreased significantly when the mesopore template agent and crystal growth inhibitor were omitted. Comparing Comparative Example 2 with Example 2, it can be seen that both the mesopore volume and micropore volume of the ZSM-23 molecular sieve in Comparative Example 2 decreased significantly when the crystal growth inhibitor was omitted. Comparing Comparative Example 1 with Example 2, it can be seen that the mesopore volume increased significantly and the micropore volume decreased when the mesopore template agent was added, resulting in an increase in the total pore volume. This is because after adding the mesopore template agent, some micropores were converted into mesopores.

[0114] (2) In Example 4, Comparative Example 4 and Comparative Example 6:

[0115] It can be seen that, when both crystal growth inhibitors and mesoporous templates are omitted, the mesoporous volume of Comparative Example 4 decreases compared to Example 4, while the micropore volume increases compared to Example 4; when crystal growth inhibitors are omitted, both the mesoporous volume and micropore volume of Comparative Example 6 decrease compared to Example 4. These results indicate that the addition of mesoporous templates significantly damages the micropores, while the addition of growth inhibitors can only increase the micropore volume to a limited extent while reducing the grain size.

[0116] (3) In Example 1 and Comparative Example 3, without omitting crystal growth inhibitors, the mesopore volume and micropore volume of Comparative Example 3 decreased compared to Example 1.

[0117] The above results indicate that adding reagents such as L-lysine as mesoporous templates is beneficial to increasing the mesopores in ZSM-23 molecular sieves; adding reagents such as tetradecyl phosphate as crystal growth inhibitors is also beneficial to increasing the mesopores in ZSM-23 molecular sieves.

[0118] The particle size of the ZSM-23 molecular sieves in the examples and comparative examples in Table 1 was analyzed as follows:

[0119] (1) In Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 5, the dimensions in the a-axis direction from largest to smallest are: Comparative Example 2 > Comparative Example 5 > Comparative Example 1 > Example 2;

[0120] (2) In Example 4, Comparative Example 4 and Comparative Example 6, the dimensions along the a-axis from largest to smallest are: Comparative Example 4 > Comparative Example 6 > Example 4;

[0121] (3) In Example 1 and Comparative Example 3, the a-axis dimension of Comparative Example 3 is larger than the a-axis dimension of Example 1.

[0122] The results above demonstrate that adding crystal growth inhibitors and mesoporous templates can effectively shorten the a-axis dimension of ZSM-23 molecular sieves. Among these, the crystal growth inhibitors show a more significant effect in inhibiting the a-axis dimension.

[0123] Test Example 1

[0124] This test example provides the performance evaluation results of the ZSM-23 molecular sieve prepared in the above embodiments as a catalyst.

[0125] ZSM-23 molecular sieves from Examples 2 and 4, and Comparative Examples 1-2 and 4-6, were used as supports for loading with the same noble metal, Pt. The loading process employed conventional methods in the art, using vacuum loading. The precursor was tetraammineplatinum(II) dichloride, and the Pt loading was 0.3%. Hydrocracking tail oil from a refining and chemical enterprise was used as feedstock, with a density (20°C) of 0.8567 g / cm³. 3 Total sulfur = 2.14 μg / g, total nitrogen < 2 μg / g, viscosity (100℃) = 8.623 mm. 2 / s, isomerization was performed. An industrial catalyst (with a noble metal loading of 0.3%) was provided as a control. The final test and evaluation data are shown in Tables 2 and 3. Yield = Mass of fraction above 460℃ / Mass of total fraction × 100%.

[0126] Table 2

[0127] Table 3

[0128] Comparing the data in Table 2, it can be seen that compared with the ZSM-23 molecular sieves of Comparative Examples 4 and 6, the yield of the ZSM-23 molecular sieve phase in Example 4 is significantly improved in the fraction above 460°C, and the product has higher viscosity and lower cloud point at 100°C. However, compared with the ZSM-23 molecular sieve of Comparative Example 6, which only omitted the crystal growth inhibitor, the ZSM-23 molecular sieve of Comparative Example 4, which omitted both the crystal growth inhibitor and the mesoporous template agent, has lower yield and viscosity and higher cloud point.

[0129] Comparing the data in Table 3, it can be seen that compared with the ZSM-23 molecular sieves of Comparative Examples 1, 2, and 5, the ZSM-23 molecular sieve phase of Example 2 has a significantly higher yield of fractions above 460°C, and the product has higher viscosity and lower cloud point at 100°C. However, compared with the ZSM-23 molecular sieve of Comparative Example 1, which omits the mesoporous template agent, the ZSM-23 molecular sieve of Comparative Example 2, which omits the crystal growth inhibitor, has lower yield and viscosity, and higher cloud point.

[0130] The above results indicate that by adding mesoporous template agents and crystal growth inhibitors during the synthesis of ZSM-23 molecular sieves, cracking products can be reduced and yield increased; moreover, crystal growth inhibitors have a greater impact on the catalytic performance of ZSM-23 molecular sieves than mesoporous template agents.

[0131] As can be seen from Tables 2 and 3, the ZSM-23 molecular sieves synthesized in Examples 3 and 4 have high yields, indicating that they have low light hydrocarbon content and low cracking rate. This further demonstrates that the ZSM-23 molecular sieve synthesized in this invention can reduce the cracking rate and increase the yield.

Claims

1. A method for preparing ZSM-23 molecular sieve, the method comprising: A raw material solution is formed by mixing silicon source, aluminum source, alkali source, organic structure guiding agent, mesoporous template agent, crystal growth inhibitor, and water. The solution is then crystallized, washed, dried, and calcined to obtain the ZSM-23 molecular sieve. The crystal growth inhibitor includes one or more of the following: trimethoxy[3-(phenylamino)propyl]silane, sodium dodecyl sulfate, tetradecyl phosphate, and glutamic acid.

2. The preparation method according to claim 1, wherein, The mesoporous template agent includes one or more of L-lysine, hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride.

3. The preparation method according to claim 1, wherein, The silicon source includes one or more of tetraethyl orthosilicate, silica sol, sodium silicate, and silica fume.

4. The preparation method according to claim 1, wherein, The aluminum source includes one or more of sodium aluminate, boehmite NB-01, aluminum isopropoxide, and aluminum sulfate.

5. The preparation method according to claim 1, wherein, The organic structure directing agent includes one or more of pyrrolidine, isopropylamine, ethylene glycol, and N,N-dimethylformamide.

6. The preparation method according to claim 1, wherein, The alkaline source includes one or a combination of two or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, barium hydroxide, and ammonia water.

7. The preparation method according to claim 1, wherein, The raw material solution satisfies the following molar ratio: SiO2:Al2O3:OH - Organic structure guiding agent: mesoporous template agent: crystal growth inhibitor: H2O = 1: 0.005-0.5: 0.01-0.8: 0.1-5: 0.001-0.09: 0.01-0.6: 20-120.

8. The preparation method according to claim 1, wherein, The raw material solution satisfies the following molar ratio: SiO2:Al2O3:OH - Organic structure guiding agent: mesoporous template agent: crystal growth inhibitor: H2O = 1: 0.008-0.3: 0.05-0.7: 0.4-3: 0.003-0.07: 0.04-0.4: 30-100.

9. The preparation method according to claim 1, wherein, The crystallization temperature is 120-200℃, and the crystallization time is 24h-120h.

10. A ZSM-23 molecular sieve, which is obtained by the preparation method according to any one of claims 1-9.

11. The ZSM-23 molecular sieve according to claim 10, wherein, The ZSM-23 molecular sieve has a particle size of 0.08-1 μm.

12. The ZSM-23 molecular sieve according to claim 10, wherein, The total pore volume of the ZSM-23 molecular sieve is 0.32 cm³. 3 / g-0.4cm 3 / g.

13. The ZSM-23 molecular sieve according to claim 10, wherein, The ZSM-23 molecular sieve has a mesopore volume of 0.24 cm³. 3 / g-0.32cm 3 / g.

14. A catalyst made from the ZSM-23 molecular sieve according to any one of claims 10-13.

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