A method for synthesizing a zsm-12 molecular sieve and the synthesized molecular sieve and applications thereof

Abstract

The application discloses a synthesis method of ZSM-12 molecular sieve, a synthesized molecular sieve and application of the synthesized molecular sieve. The method comprises the following steps: mixing an aluminum source, a silicon source, sodium hydroxide, a template agent, N-methyl-2-pyrrolidone and water, crystallizing in a closed container, washing, separating, drying, and obtaining the ZSM-12 molecular sieve. By changing the amount of NMP and reasonably matching the synthesis conditions, the ZSM-12 molecular sieve in a coral shape is obtained, the product has high crystallinity, and the efficient, stable and economic synthesis of the ZSM-12 molecular sieve can be realized.

Description

Technical Field

[0001] This application relates to a method for synthesizing ZSM-12 molecular sieve, the synthesized molecular sieve, and its applications, belonging to the field of molecular sieves. Background Technology

[0002] ZSM-12 molecular sieve (US3832449A) is a molecular sieve developed by Mobil Petroleum Corporation in the United States. It features a one-dimensional linear non-cross-channel structure with an MTW (Medium-Through) pore size of [missing information]. Its unique pore structure and adjustable acidity make it widely used in petroleum refining reaction processes, exhibiting excellent catalytic performance.

[0003] Currently, the most commonly used organic template agents for synthesizing ZSM-12 molecular sieves are tetraethylammonium (TEA). + ) ions, methyltriethylammonium (MTEA) + ( ) halogenated compounds or hydroxides of ions. ZSM-12 molecular sieves prepared with different template agents have different morphologies. (Based on MTEA) + Molecular sieves synthesized using TEA as a template agent are mostly spindle-shaped with a grain size of approximately 2-5 μm; + Most molecular sieves synthesized using template agents are cubic in shape. The morphology of molecular sieves affects the diffusion of reactant molecules within the sieve crystal and their catalytic activity. Therefore, the synthesis of ZSM-12 molecular sieves with special morphologies has attracted widespread attention from researchers both domestically and internationally. CN106564909A discloses a two-stage hydrothermal crystallization method for preparing six-lobed snowflake-shaped ZSM-12 zeolite molecular sieves using 1,n-bis(N-methylpyrrolidine)alkyl styrene chloride (n=4-6) as a structure-directing agent. CN103922362A discloses a method for synthesizing ZSM-12 molecular sieves using 1,n-bis(N-methylpyrrolidine)alkane divalent cations (n=3-7) as structure-directing agents; the resulting ZSM-12 molecular sieves have a regular morphology, exhibiting a 10 μm hexagonal disk shape. CN116022805A discloses a method for preparing small-crystal ZSM12 molecular sieves, using a silica-alumina gel with a high silica-alumina ratio as a composite silica-alumina source and 1,4-bis(N-methylpyrrolidine)butane halide as a template agent. The synthesized ZSM12 molecular sieves have a crystal size between 100 and 200 nm.

[0004] The methods described above for synthesizing ZSM-12 molecular sieves with special morphologies all suffer from problems such as cumbersome synthesis steps and expensive template agents. Therefore, it is of great significance to develop an efficient, stable, and economical method for synthesizing ZSM-12 molecular sieves with special morphologies. Summary of the Invention

[0005] This invention develops a method for synthesizing ZSM-12 molecular sieves. By changing the amount of NMP and reasonably matching the synthesis conditions, coral-shaped ZSM-12 molecular sieves are obtained. The synthesized ZSM-12 molecular sieves have high crystallinity and an adjustable silicon-aluminum ratio.

[0006] According to one aspect of this application, a method for synthesizing ZSM-12 molecular sieves is provided, comprising the following steps:

[0007] An aluminum source, a silicon source, sodium hydroxide, a template agent, N-methyl-2-pyrrolidone, and water are mixed in a sealed container, crystallized, washed, separated, and dried to obtain the ZSM-12 molecular sieve.

[0008] Optionally, the following steps are included:

[0009] Aluminum source, silicon source, sodium hydroxide, template agent and water are mixed and stirred thoroughly. Then N-methyl-2-pyrrolidone is added and mixed thoroughly. The mixture is then crystallized, washed, separated and dried in a sealed container to obtain the ZSM-12 molecular sieve.

[0010] The aluminum source is selected from one of sodium aluminate, boehmite, aluminum chloride, aluminum sulfate, aluminum nitrate, or aluminum hydroxide.

[0011] The silicon source is selected from one of solid silica gel, fumed silica, silica sol or tetraethyl orthosilicate;

[0012] The template agent is at least one of methyltriethylammonium chloride (MTEACl), methyltriethylammonium bromide (MTEABr), and methyltriethylammonium hydroxide (MTEAOH).

[0013] The molar ratio of the silicon source to the aluminum source is 50 to 200;

[0014] The molar ratio of the template agent to the silicon source is 0.2 to 0.3;

[0015] The molar ratio of sodium hydroxide to silicon source is 0.05 to 0.10;

[0016] The molar ratio of water to silicon source is 10 to 20;

[0017] The molar ratio of N-methyl-2-pyrrolidone to the silicon source is 0.5 to 1.0;

[0018] The molar amount of silicon source is measured by the molar amount of silicon dioxide contained therein.

[0019] The crystallization temperature is 140–170°C;

[0020] The crystallization time is 36–72 hours.

[0021] According to another aspect of this application, a ZSM-12 molecular sieve prepared by the above-described preparation method is provided, wherein the ZSM-12 molecular sieve has a coral-like morphology.

[0022] The synthesized ZSM-12 molecular sieve is a sodium-type molecular sieve. It can be obtained as a hydrogen-type ZSM-12 molecular sieve through calcination and ion exchange, or as a functionalized ZSM-12 molecular sieve through other post-processing methods.

[0023] According to another aspect of this application, an application of the above-mentioned ZSM-12 molecular sieve is provided for the alkylation reaction of light aromatics with isobutylene;

[0024] The light aromatic hydrocarbon is selected from at least one of toluene and ethylbenzene.

[0025] The beneficial effects that this application can produce include:

[0026] This application discloses a method for synthesizing ZSM-12 molecular sieve, the synthesized molecular sieve, and its applications.

[0027] By changing the amount of NMP and properly matching the synthesis conditions, coral-shaped ZSM-12 molecular sieves were obtained. The product has high crystallinity, and the efficient, stable and economical synthesis of ZSM-12 molecular sieves can be achieved. Attached Figure Description

[0028] Figure 1 The image shows the X-ray diffraction pattern of the product from Example 1.

[0029] Figure 2 The image shown is a scanning electron microscope image of the product from Example 1, with a scale of 2 μm. Detailed Implementation

[0030] The present invention will be further illustrated by the following examples, but the present invention is not limited to the examples listed.

[0031] Example 1

[0032] The raw materials used are as follows:

[0033] 1. Silica sol (30.0 wt% SiO2);

[0034] 2. Sodium aluminate (16.0 wt% Al2O3);

[0035] 3. Sodium hydroxide (99.0 wt%);

[0036] 4. Methyltriethylammonium chloride (98.0 wt%)

[0037] 5. Deionized water (homemade);

[0038] 6. N-methyl-2-pyrrolidone (99.0 wt%).

[0039] According to the molar ratio: 0.06Na₂O: 0.014Al₂O₃: 1.0SiO₂: 0.25MTEACl: 12H₂O: 0.75NMP, 200g silica sol, 8.9g sodium aluminate, 38.3g MTEACl, 3.7g sodium hydroxide, 69.4g deionized water, and 75g NMP were mixed in a specific order and stirred until homogeneous. The mixture was then added to a stainless steel reactor and sealed, allowing it to crystallize dynamically at 150℃ for 60 hours. The solid product was washed with deionized water until the washing solution was neutral. After centrifugation and drying, the ZSM-12 molecular sieve was obtained. Its X-ray diffraction (XRD) spectrum (…) Figure 1 The scanning electron microscope image shows that it is a pure-phase ZSM-12 molecular sieve. Figure 2 It shows that its shape is coral-shaped.

[0040] Example 2

[0041] The raw materials used are as follows:

[0042] 1. Silica gel (dry basis 92.7wt%);

[0043] 2. Boehmite (77.5 wt% on a dry basis);

[0044] 3. Sodium hydroxide (99.0 wt%);

[0045] 4. Methyltriethylammonium bromide (99.0 wt%)

[0046] 5. Deionized water (homemade);

[0047] 6. N-methyl-2-pyrrolidone (99.0 wt%).

[0048] According to the molar ratio of 0.05Na₂O:0.01Al₂O₃:1.0SiO₂:0.2MTEABr:20H₂O:1.0NMP, 64.7g silica gel, 1.3g boehmite, 39.2g MTEABr, 4.0g sodium hydroxide, 355g deionized water, and 100g NMP were mixed in a specific order and stirred until homogeneous. The mixture was then added to a synthesis vessel and sealed. Dynamic crystallization was carried out at 160℃ for 48h. The solid product was washed with deionized water until the washings were neutral, and the solid product was obtained by centrifugation. It was dried overnight at 120℃ to obtain the ZSM-12 molecular sieve product, whose X-ray diffraction (XRD) spectrum is similar to... Figure 1 Similarly, its scanning electron microscope (SEM) images are similar to Figure 2 similar.

[0049] Example 3

[0050] The raw materials used are as follows:

[0051] 1. Silica (86.6 wt% on a dry basis);

[0052] 2. Sodium aluminate (16.0 wt% Al2O3);

[0053] 3. Sodium hydroxide (99.0 wt%);

[0054] 4. Methyltriethylammonium hydroxide (20.0 wt%)

[0055] 5. Deionized water (homemade);

[0056] 6. N-methyl-2-pyrrolidone (99.0 wt%).

[0057] According to the molar ratio of 0.10 Na₂O: 0.01 Al₂O₃: 1.0 SiO₂: 0.30 MTEAOH: 15 H₂O: 0.5 NMP, 69.3 g of silica, 6.4 g of sodium aluminate, 7.2 g of sodium hydroxide, 199.8 mL of MTEAOH solution, 96.1 g of deionized water, and 50 g of NMP were mixed in a specific order and stirred until homogeneous. The mixture was then added to a synthesis vessel, sealed, and dynamically crystallized at 140 °C for 72 h. The solid product was washed with deionized water until the washings were neutral. The solid product was obtained by centrifugation, and its X-ray diffraction (XRD) spectrum was consistent with... Figure 1 Similarly, its scanning electron microscope (SEM) images are similar to Figure 2 similar.

[0058] Example 4

[0059] The raw materials used are as follows:

[0060] 1. Silica (86.6 wt% on a dry basis);

[0061] 2. Aluminum chloride hexahydrate (99.9 wt%);

[0062] 3. Sodium hydroxide (99.0 wt%);

[0063] 4. Methyltriethylammonium chloride (98 wt%)

[0064] 5. Deionized water (homemade);

[0065] 6. N-methyl-2-pyrrolidone (99.0 wt%).

[0066] According to the molar ratio of 0.10Na₂O:0.005Al₂O₃:1.0SiO₂:0.25MTEACl:10H₂O:0.8NMP, 69.3g of silica, 2.4g of aluminum chloride hexahydrate, 8.0g of sodium hydroxide, 38.3g of MTEACl, 170.7g of deionized water, and 80g of NMP were mixed in a specific order and stirred until homogeneous. The mixture was then added to a synthesis reactor, sealed, and dynamically crystallized at 170℃ for 36 hours. The solid product was washed with deionized water until the washing solution was neutral. The solid product was obtained by centrifugation, and its X-ray diffraction (XRD) spectrum was consistent with... Figure 1 Similarly, its scanning electron microscope (SEM) images are similar to Figure 2 similar.

[0067] Example 5

[0068] The raw materials used are as follows:

[0069] 1. Tetraethyl orthosilicate (28.4 wt% SiO2);

[0070] 2. Aluminum sulfate (99.0 wt%);

[0071] 3. Sodium hydroxide (99.0 wt%);

[0072] 4. Methyltriethylammonium chloride (98 wt%)

[0073] 5. Deionized water (homemade);

[0074] 6. N-methyl-2-pyrrolidone (99.0 wt%).

[0075] According to the molar ratio of 0.05Na₂O:0.01Al₂O₃:1.0SiO₂:10H₂O:0.25MTEACl:0.75NMP, 211.3g of tetraethyl orthosilicate, 3.4g of aluminum sulfate, 4.0g of sodium hydroxide, 38.3g of MTEACl, 180g of deionized water, and 75g of NMP were mixed in a specific order and stirred until homogeneous. The mixture was then added to a synthesis vessel, sealed, and dynamically crystallized at 155℃ for 48 hours. The solid product was washed with deionized water until the washings were neutral. The solid product was obtained by centrifugation, and its X-ray diffraction (XRD) spectrum was consistent with... Figure 1 Similarly, its scanning electron microscope (SEM) images are similar to Figure 2 similar.

[0076] Example 6

[0077] The raw materials used are as follows:

[0078] 1. Silica sol (30.0 wt% SiO2);

[0079] 2. Aluminum hydroxide (99.9 wt%);

[0080] 3. Sodium hydroxide (99.0 wt%);

[0081] 4. Methyltriethylammonium bromide (99.0 wt%)

[0082] 5. Deionized water (homemade);

[0083] 6. N-methyl-2-pyrrolidone (99.0 wt%).

[0084] According to the molar ratio of 0.1Na₂O:0.02Al₂O₃:1.0SiO₂:15H₂O:0.25MTEABr:1.0NMP, 200g silica sol, 1.6g aluminum hydroxide, 8.0g sodium hydroxide, 39.2g MTEABr, 130g deionized water, and 100g NMP were mixed in a specific order and stirred until homogeneous. The mixture was then added to a synthesis vessel, sealed, and dynamically crystallized at 150℃ for 48h. The solid product was washed with deionized water until the washing solution was neutral. The solid product was obtained by centrifugation, and its X-ray diffraction (XRD) spectrum was consistent with... Figure 1 Similarly, its scanning electron microscope (SEM) images are similar to Figure 2 similar.

[0085] Example 7

[0086] The raw materials used are as follows:

[0087] 1. Silica gel (dry basis 92.7wt%);

[0088] 2. Aluminum nitrate nonahydrate (99.0 wt%);

[0089] 3. Sodium hydroxide (99.0 wt%);

[0090] 4. Methyltriethylammonium chloride (99 wt%)

[0091] 5. Deionized water (homemade);

[0092] 6. N-methyl-2-pyrrolidone (99.0 wt%).

[0093] According to the molar ratio of 0.10Na₂O:0.01Al₂O₃:1.0SiO₂:20H₂O:0.25MTEACl:0.75NMP, 64.7g silica gel, 3.8g aluminum nitrate, 8.0g sodium hydroxide, 38.3g MTEACl, 353.6g deionized water, and 75g NMP were mixed in a specific order and stirred until homogeneous. The mixture was then added to a synthesis vessel, sealed, and dynamically crystallized at 170℃ for 36 hours. The solid product was washed with deionized water until the washings were neutral. The solid product was obtained by centrifugation, and its X-ray diffraction (XRD) spectrum was consistent with... Figure 1 Similarly, its scanning electron microscope (SEM) images are similar to Figure 2 similar.

[0094] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A method for synthesizing ZSM-12 molecular sieve, characterized in that, Includes the following steps: An aluminum source, a silicon source, sodium hydroxide, a template agent, N-methyl-2-pyrrolidone, and water are mixed in a sealed container, crystallized, washed, separated, and dried to obtain the ZSM-12 molecular sieve.

2. The method according to claim 1, characterized in that, Includes the following steps: Aluminum source, silicon source, sodium hydroxide, template agent and water are mixed and stirred thoroughly. Then N-methyl-2-pyrrolidone is added and mixed thoroughly. The mixture is then crystallized, washed, separated and dried in a sealed container to obtain the ZSM-12 molecular sieve.

3. The method according to claim 1, characterized in that, The aluminum source is selected from one of sodium aluminate, boehmite, aluminum chloride, aluminum sulfate, aluminum nitrate, or aluminum hydroxide. The silicon source is selected from one of solid silica gel, fumed silica, silica sol or tetraethyl orthosilicate; The template agent is at least one of methyltriethylammonium chloride, methyltriethylammonium bromide, and methyltriethylammonium hydroxide.

4. The method according to claim 1, characterized in that, The molar ratio of the silicon source to the aluminum source is 50 to 200; The molar ratio of the template agent to the silicon source is 0.2 to 0.3; The molar ratio of sodium hydroxide to silicon source is 0.05 to 0.10; The molar ratio of water to silicon source is 10 to 20; The molar ratio of N-methyl-2-pyrrolidone to the silicon source is 0.25 to 1.0; The molar amount of silicon source is calculated as the molar amount of silicon dioxide therein, and the molar amount of aluminum source is calculated as the molar amount of aluminum oxide therein.

5. The method according to claim 1, characterized in that, The crystallization temperature is 140–170°C; The crystallization time is 36–72 hours.

6. A ZSM-12 molecular sieve prepared by the preparation method according to any one of claims 1 to 5, characterized in that, The ZSM-12 molecular sieve has a coral-like morphology.

7. An application of the ZSM-12 molecular sieve according to claim 6, characterized in that, Used in the alkylation reaction of light aromatics with isobutylene; The light aromatic hydrocarbon is selected from at least one of toluene and ethylbenzene.

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