A molecular sieve crystallization aid, its preparation method and application

Abstract

This invention discloses a molecular sieve crystallization aid, its preparation method, and its application. The two-dimensional image of the crystals in this molecular sieve crystallization aid is rectangular, with a length dimension of 5.0-18.0 nm and a width dimension of 2.0-6.0 nm, resulting in a length-to-width ratio of 1.5-3.5. Adding this molecular sieve crystallization aid to the formulation of conventional synthetic molecular sieves can significantly shorten the crystallization time and reduce the crystal size of the molecular sieve.

Description

Technical Field

[0001] This invention belongs to the technical field of catalytic chemistry and chemical engineering, and in particular relates to a molecular sieve crystallization aid, its preparation method and application. Background Technology

[0002] In order to shorten the crystallization time of molecular sieves, reduce the crystal size, or obtain molecular sieve products with special morphologies, specific additives are usually added during the molecular sieve crystallization process to assist crystallization.

[0003] Patent CN110217804A discloses a ZSM-5 molecular sieve, its preparation method, a hydrogen-form ZSM-5 molecular sieve, its application, and a method for methanol conversion. In this method, spherical ZSM-5 molecular sieves containing a template agent are added as seed crystals during the ZSM-5 molecular sieve crystallization process. The resulting molecular sieve significantly improves the selectivity of propylene and butene in methanol conversion to olefins and extends the catalyst lifetime. While this method uses seed crystals to assist crystallization, the seed crystals are spherical ZSM-5 molecular sieve powder containing a template agent. Since the synthesis process of ZSM-5 molecular sieve powder is lengthy, this undoubtedly increases the production cost of the final product.

[0004] Patent CN114573003A discloses a method for synthesizing SSZ-39 molecular sieves using a seed crystal method. In this method, pre-synthesized SSZ-39 molecular sieve powder is added as a seed crystal to assist crystallization, resulting in a cubic morphology and uniform particle size of the obtained SSZ-39 molecular sieve. However, this method also involves adding SSZ-39 molecular sieve powder, which has a relatively long synthesis process, to assist crystallization, leading to a longer production cycle and a significant increase in cost for the final product.

[0005] Patent CN105645430A discloses a method for rapid synthesis of Ti-MWW molecular sieves using a seed crystal method. First, seed crystals are added to a reaction gel. Then, the reaction gel is sealed in a crystallization vessel. The crystallization vessel is then rotated along a horizontal axis for aging and crystallization. The total time for this process is greater than or equal to 48 hours and less than or equal to 60 hours, significantly shortening the synthesis time of Ti-MWW molecular sieves and saving production costs. The seed crystals play an auxiliary role in the crystallization process, effectively shortening the crystallization time. The seed crystals disclosed in this method are Ti-MWW molecular sieve raw powder.

[0006] In summary, as can be seen from the publicly reported literature, adding molecular sieve powder as a seed crystal to assist crystallization during molecular sieve synthesis can change the morphology of the molecular sieve or shorten the crystallization time. However, the molecular sieve powder synthesis process is lengthy, generally involving steps such as batching, gelation, crystallization, solid-liquid separation, drying, and calcination. In actual industrial production, this will undoubtedly lead to a significant increase in the production cost of the finished molecular sieve product and a longer production cycle. Furthermore, the production process will generate some ammonia nitrogen wastewater containing organic amines, which is environmentally unfriendly. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, this invention provides a molecular sieve crystallization aid, its preparation method, and its application. Using the molecular sieve crystallization aid of this invention can effectively alter the crystal morphology of molecular sieves, improve catalytic performance, significantly shorten the crystallization time of molecular sieves, and reduce production costs.

[0008] The first aspect of this invention provides a method for preparing a molecular sieve crystallization aid, comprising the following steps:

[0009] (a) A mixture A is obtained by contacting a silicon source, an aluminum source, water, organic matter 1, and organic matter 2;

[0010] (b) The mixture A is treated to obtain a molecular sieve crystallization aid.

[0011] In the above technical solution, preferably, the silicon source in step (a) is one or more of tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, and tetraphenyl silicate, and more preferably one or more of tetraethyl silicate, tetrapropyl silicate, and tetraphenyl silicate.

[0012] In the above technical solution, preferably, the aluminum source in step (a) is one or more of aluminum sulfate, aluminum isopropoxide, sodium aluminate, and boehmite, and more preferably one or more of aluminum sulfate and boehmite.

[0013] In the above technical solution, preferably, the organic compound 1 in step (a) is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, ethylamine, ethylenediamine, n-butylamine, butanediamine, hexamethyleneimine, piperidine, piperazine, and dicyclohexylamine, and more preferably one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, ethylamine, n-butylamine, and hexamethyleneimine.

[0014] In the above technical solution, preferably, the organic compound 2 in step (a) has the structural formula shown in Formula I, wherein R1-R6 are each independently selected from methyl, ethyl, propyl or phenyl, and at least one group in R1-R6 is phenyl. Preferably, there are 4 to 6 phenyl groups in R1-R6.

[0015]

[0016] In the above technical solution, preferably, the molar ratio of silicon source, aluminum source, water, and organic matter 1 in step (a) is silicon source: aluminum source: water: organic matter 1 = 1:(0-0.05):(5-30):(0.1-1), where the silicon source is calculated as SiO2 and the aluminum source is calculated as Al2O3. The ratio of the mass of organic matter 2 to the sum of the masses of silicon source, aluminum source, water, and organic matter 1 is (0.05-0.2):1, where the total mass is calculated according to the actual mass of the substances.

[0017] In the above technical solution, preferably, the treatment in step (b) is carried out under stirring, and the treatment conditions are 60-85℃ for 4-24 hours, preferably in a sealed environment.

[0018] A second aspect of the present invention provides a molecular sieve crystallization aid prepared by the above-described preparation method.

[0019] In the above technical solution, the two-dimensional image of the crystal in the molecular sieve crystallization aid is rectangular, the length of the crystal is 5.0-18.0 nm, the width is 2.0-6.0 nm, and the length-to-width ratio is 1.5-3.5.

[0020] In the above technical solution, preferably, the length of the crystal is 5.0-15.0 nm and the width is 2.5-5.0 nm.

[0021] In the above technical solution, preferably, the molecular sieve crystallization aid contains phenyl, and the content of phenyl is 1.5%-15% based on the mass of the aid, preferably 5%-15%.

[0022] In the above technical solution, preferably, the molecular sieve crystallization aid is a suspension under normal temperature and pressure conditions.

[0023] A third aspect of the present invention provides the application of the above-mentioned molecular sieve crystallization aid in molecular sieve synthesis.

[0024] In the above technical solutions, preferably, the molecular sieve crystallization aid is used in the synthesis of silicon-aluminum molecular sieves containing 10-membered ring structures or 12-membered ring structures.

[0025] In the above technical solution, preferably, the silica-alumina molecular sieve is a ZSM-5 molecular sieve.

[0026] In the above technical solution, preferably, the preparation method of the ZSM-5 molecular sieve includes: mixing a silicon source, an aluminum source, an alkali source, an organic template agent, the molecular sieve crystallization aid, and water, and crystallizing to obtain the ZSM-5 molecular sieve.

[0027] In the above technical solution, the silicon source, aluminum source, alkali, and organic template agent are the silicon source, aluminum source, alkali source, and organic template agent conventionally used in the synthesis of ZSM-5 in this field.

[0028] In the above technical solution, the reaction mixture is in the following molar ratio: SiO2:Al2O3:template agent:OH-:H2O=1:(0.005~0.05):(0.05~0.2):(0.01~0.1):(10~20).

[0029] In the above technical solution, the ratio of the mass of phenyl in the molecular sieve crystallization aid to the total mass of silicon source (SiO2) and aluminum source (Al2O3) is (0.005~0.06):1.

[0030] In the above technical solution, the crystallization temperature is 150-180℃, and the crystallization time is 6-30 hours, preferably 10-12 hours.

[0031] In the above technical solution, the crystal size of the ZSM-5 molecular sieve is 30-800 nm, preferably 50-400 nm.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The molecular sieve crystallization aid of the present invention is a suspension under normal temperature and pressure conditions. The crystals in the molecular sieve crystallization aid are small in size, with a length range of only 5.0-18.0 nm and a width range of only 2.0-6.0 nm. Compared with conventional powdered molecular sieve crystallization aids, it has the advantage of having a small and large number of crystal nuclei during the molecular sieve crystallization process, which can significantly shorten the crystallization time of the molecular sieve and reduce the crystal size of the molecular sieve.

[0034] 2. The inventors discovered through research that by controlling the phenyl content in organic matter 2 and the processing temperature, the specific molecular sieve crystallization aid of this invention can be obtained. In particular, controlling the phenyl content in organic matter 2 is beneficial to inhibiting crystal growth during the molecular sieve crystallization process, thus acting as a growth inhibitor and reducing the molecular sieve crystal size. Controlling the processing temperature results in a large number of crystal nuclei in the molecular sieve crystallization aid, which is beneficial to accelerate the nucleation rate and shorten the molecular sieve crystallization time during the molecular sieve crystallization process. Attached Figure Description

[0035] Figure 1 This is a TEM image of the crystals in the molecular sieve crystallization aid prepared in Example 1 of the present invention;

[0036] Figure 2 This is a TEM image of the crystals in the molecular sieve crystallization aid prepared in Comparative Example 1 of this invention;

[0037] Figure 3This is a TEM image of the crystals in the molecular sieve crystallization aid prepared in Comparative Example 2 of this invention;

[0038] Figure 4 The XRD pattern of the molecular sieve prepared in Example 4 of this invention;

[0039] Figure 5 This is a SEM image of the molecular sieve prepared in Example 4 of the present invention;

[0040] Figure 6 The XRD pattern of the molecular sieve prepared in Comparative Example 3 of this invention is shown.

[0041] Figure 7 The XRD pattern of the molecular sieve prepared in Comparative Example 4 of this invention is shown.

[0042] Figure 8 This is a SEM image of the molecular sieve prepared in Comparative Example 4 of this invention. Detailed Implementation

[0043] The present invention will now be described in detail with reference to specific embodiments, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0044] In this invention, the size of the crystals in the molecular sieve crystallization aid is obtained by analyzing TEM images. TEM images are obtained using a G2F30 transmission electron microscope manufactured by FEI Corporation, USA. Before testing, a large amount of ethanol is added to the sample to be tested and ultrasonically dispersed evenly. Then, the suspension is dropped onto a copper grid, and the test can be performed after the ethanol has completely evaporated.

[0045] In this invention, the XRD pattern of the molecular sieve was obtained using a Rigaku Ultima IV X-ray powder diffractometer (Japan). The voltage was set to 35 kV, the current to 30 mA, and the scan rate to 1°·min⁻¹. 1 When scanning with a wide angle, the 2θ angle is 5-35°.

[0046] In this invention, SEM images were obtained using a Hitachi S-4800 cold field emission high-resolution scanning electron microscope manufactured by Hitachi Corporation.

[0047]

Example 1

[0048] This embodiment is used to synthesize a molecular sieve crystallization aid. The specific preparation process is as follows: 208.3 g of tetraethyl silicate, 6.7 g of aluminum sulfate octadechydrate, 360 g of water, 61 g of tetrapropylammonium hydroxide, and 63.6 g of organic compound 2 (the structural formula of organic compound 2 is...) are added. (where R1, R3, R4, and R6 are phenyl groups, and R2 and R5 are methyl groups) are mixed evenly to obtain mixture A1. Then, mixture A1 is stirred in a closed space at 70°C for 5 hours. After the treatment, it is cooled to room temperature to obtain molecular sieve crystallization aid B1.

[0049] TEM image of crystal B1 in molecular sieve crystallization aid as shown Figure 1 As shown, the two-dimensional image is rectangular, with a length of 13.2 nm and a width of 4.2 nm, resulting in a length-to-width ratio of 3.1. Calculations indicate that the phenyl content in the molecular sieve crystallization aid is 6.9%.

[0050]

Example 2

[0051] This embodiment is used to synthesize a molecular sieve crystallization aid. The specific preparation process is as follows: 400g of tetraphenyl silicate, 540g of water, 147g of tetraethylammonium hydroxide, and 54.4g of organic compound 2 (the structural formula of organic compound 2 is...) are mixed. Where R1 and R4 are phenyl, and R2, R3, R5 and R6 are methyl) are mixed evenly to obtain mixture A2. Then, mixture A2 is treated in a closed space at 85°C for 4 hours. After the treatment, it is cooled to room temperature to obtain molecular sieve crystallization aid B2.

[0052] The TEM image of crystal B2 in the molecular sieve crystallization aid is a rectangular two-dimensional image with a length dimension of 18.0 nm and a width dimension of 5.6 nm, resulting in a length-to-width ratio of 3.2. Calculations indicate that the phenyl content in the molecular sieve crystallization aid is 1.6%.

[0053]

Example 3

[0054] This embodiment is used to synthesize a molecular sieve crystallization aid. The specific preparation process is as follows: 208.3 g of tetraethyl silicate, 5.1 g of boehmite, 90 g of water, 20.3 g of tetrapropylammonium hydroxide, and 64.7 g of organic compound 2 (the structural formula of organic compound 2 is...) are added. (where R1, R2, R3, R4, R5 and R6 are all phenyl) are mixed evenly to obtain mixture A3. Then, mixture A3 is stirred in a closed space at 60°C for 24 hours. After the treatment, it is cooled to room temperature to obtain molecular sieve crystallization aid B3.

[0055] The TEM image of crystal B3 in the molecular sieve crystallization aid is a rectangular two-dimensional image with a length dimension of 5.0 nm and a width dimension of 2.8 nm, resulting in a length-to-width ratio of 1.8. Calculations indicate that the phenyl content in the molecular sieve crystallization aid is 14.4%.

[0056] Comparative Example 1

[0057] Compared with Example 1, the only difference is that no organic matter 2 was added. The specific preparation process is as follows: 208.3 g of tetraethyl silicate, 6.7 g of aluminum sulfate octadecyl water, 360 g of water and 61 g of tetrapropylammonium hydroxide were mixed evenly to obtain mixture A4. Then, mixture A4 was stirred in a closed space at 70°C for 5 hours. After the treatment, it was cooled to room temperature to obtain molecular sieve crystallization aid B4.

[0058] TEM image of crystal B4 in molecular sieve crystallization aid as shown below Figure 2 As shown, the two-dimensional image is approximately circular, with a size of 50-60 nm. The phenyl content in the molecular sieve crystallization aid is 0.

[0059] Comparative Example 2

[0060] Compared with Example 1, the only difference is that an equal mass of vinyltriethoxysilane is used to replace organic compound 2. The specific preparation process is as follows: 208.3 g of tetraethyl silicate, 6.7 g of aluminum sulfate octadecyl water, 360 g of water, 61 g of tetrapropylammonium hydroxide and 63.6 g of vinyltriethoxysilane are mixed evenly to obtain mixture A5. Then, mixture A5 is stirred in a closed space at 70°C for 5 hours. After the treatment, it is cooled to room temperature to obtain molecular sieve crystallization aid B5.

[0061] TEM images of crystal B5 in molecular sieve crystallization aids are shown below. Figure 3 As shown, the two-dimensional image is approximately circular and exhibits adhesion, with a size of 70-90 nm. The phenyl content in the molecular sieve crystallization aid is 0.

[0062]

Example 4

[0063] The molecular sieve crystallization aid B1 prepared in Example 1 was added to the molecular sieve synthesis mother liquor to synthesize ZSM-5 molecular sieves, specifically as follows: 60 g of silica, 6.7 g of aluminum sulfate octadecylhydrate, 270 g of water, 20.3 g of tetrapropylammonium hydroxide, 2 g of sodium hydroxide, and 12 g of molecular sieve crystallization aid B1 were mixed evenly, and then treated at 160°C for 12 hours in a sealed space. After treatment, the mixture was cooled, centrifuged, dried at 120°C for 10 hours, and calcined at 550°C for 5 hours to obtain molecular sieve C1. The XRD pattern of molecular sieve C1 is shown below. Figure 4 As shown, these are typical characteristic peaks of ZSM-5 molecular sieve. The SEM image of molecular sieve C1 is shown below. Figure 5 As shown, the grain size is 220-400nm.

[0064] Comparative Example 3

[0065] Compared with Example 4, the only difference is that molecular sieve crystallization aid B1 was not added during the molecular sieve synthesis process. Specifically, 60 g of silica, 6.7 g of aluminum sulfate octadechydrate, 270 g of water, 20.3 g of tetrapropylammonium hydroxide, and 2 g of sodium hydroxide were mixed evenly and then treated at 160°C for 12 hours in a sealed space. After treatment, the mixture was cooled, centrifuged, dried at 120°C for 10 hours, and calcined at 550°C for 5 hours to obtain molecular sieve C2. The XRD pattern of molecular sieve C2 is shown below. Figure 6 As shown, the XRD baseline is uneven, and bulges appear at an angle of about 20-25 degrees at 2Theta, indicating that the molecular sieve is not completely crystallized.

[0066] Comparative Example 4

[0067] Compared with Example 4, the difference is that molecular sieve crystallization aid B1 was not added during the molecular sieve synthesis process, and the sealed treatment time was extended to 48 hours, as follows: 60 g of silica, 6.7 g of aluminum sulfate octadechydrate, 270 g of water, 20.3 g of tetrapropylammonium hydroxide, and 2 g of sodium hydroxide were mixed evenly, and then treated in a sealed space at 160°C for 48 hours. After the treatment, the mixture was cooled, centrifuged, dried at 120°C for 10 hours, and calcined at 550°C for 5 hours to obtain molecular sieve C3. The XRD pattern of molecular sieve C3 is shown below. Figure 7 As shown, these are typical characteristic peaks of ZSM-5 molecular sieve. The SEM image of molecular sieve C3 is shown below. Figure 8 As shown, the crystal size is 660-1100 nm. This demonstrates that adding the molecular sieve crystallization aid prepared in this invention during the molecular sieve synthesis process can significantly shorten the crystallization time and reduce the crystal size of the molecular sieve.

[0068]

Example 5

[0069] Compared with Example 4, the difference lies in the addition of crystallization aid B2 from Example 2 during the molecular sieve synthesis process, and the extended sealing treatment time to 16 hours. Specifically, the molecular sieve crystallization aid B2 prepared in Example 2 was added to the molecular sieve synthesis mother liquor for ZSM-5 molecular sieve synthesis. Specifically, 60 g of silica, 6.7 g of aluminum sulfate octadecylhydrate, 270 g of water, 20.3 g of tetrapropylammonium hydroxide, 2 g of sodium hydroxide, and 12 g of molecular sieve crystallization aid B2 were mixed evenly, and then treated in a sealed space at 160°C for 16 hours. After treatment, the mixture was cooled, centrifuged, dried at 120°C for 10 hours, and calcined at 550°C for 5 hours to obtain molecular sieve C4. The XRD pattern of molecular sieve C4 is similar to... Figure 4 Similarly, the characteristic peaks of typical ZSM-5 molecular sieves are shown in the SEM image of molecular sieve C4. Figure 5 Similarly, the crystal size of molecular sieve C4 is 430-650 nm.

[0070]

Example 6

[0071] Compared with Example 4, the difference lies in the addition of crystallization aid B3 from Example 3 during the molecular sieve synthesis process. Specifically, the molecular sieve crystallization aid B3 prepared in Example 3 was added to the molecular sieve synthesis mother liquor for ZSM-5 molecular sieve synthesis. Specifically, 60 g of silica, 6.7 g of aluminum sulfate octadechydrate, 270 g of water, 20.3 g of tetrapropylammonium hydroxide, 2 g of sodium hydroxide, and 12 g of molecular sieve crystallization aid B3 were mixed evenly and then treated at 160°C for 12 hours in a sealed space. After treatment, the mixture was cooled, centrifuged, dried at 120°C for 10 hours, and calcined at 550°C for 5 hours to obtain molecular sieve C5. The XRD pattern of molecular sieve C5 is similar to... Figure 4 Similarly, the characteristic peaks of typical ZSM-5 molecular sieves are shown in the SEM image of molecular sieve C5. Figure 5 Similarly, the crystal size of molecular sieve C5 is 160-350 nm.

[0072]

Example 7

[0073] Compared to Example 4, the difference lies in changing the proportions of each material in the molecular sieve synthesis mother liquor. Specifically, 60g of silica, 30g of aluminum sulfate octadechydrate, 360g of water, 40g of tetrapropylammonium hydroxide, 4g of sodium hydroxide, and 20g of molecular sieve crystallization aid B1 were mixed evenly, then treated at 170°C for 10 hours in a sealed space. After treatment, the mixture was cooled, centrifuged, dried at 120°C for 10 hours, and calcined at 550°C for 5 hours to obtain molecular sieve C9. The XRD pattern of molecular sieve C9 is similar to... Figure 4 Similarly, the characteristic peaks of typical ZSM-5 molecular sieves are shown in the SEM image of molecular sieve C9. Figure 5 Similarly, the crystal size of molecular sieve C9 is 200-360 nm.

[0074] Comparative Example 5

[0075] Compared with Example 4, the difference lies in the addition of crystallization aid B4 from Comparative Example 1 during the molecular sieve synthesis process, and the extended sealing treatment time to 36 hours. Specifically, the molecular sieve crystallization aid B4 prepared in Comparative Example 1 was added to the molecular sieve synthesis mother liquor for ZSM-5 molecular sieve synthesis. Specifically, 60 g of silica, 6.7 g of aluminum sulfate octadecylhydrate, 270 g of water, 20.3 g of tetrapropylammonium hydroxide, 2 g of sodium hydroxide, and 12 g of molecular sieve crystallization aid B4 were mixed evenly, and then treated in a sealed space at 160°C for 36 hours. After the treatment, the mixture was cooled, centrifuged, dried at 120°C for 10 hours, and calcined at 550°C for 5 hours to obtain molecular sieve C6. The XRD pattern of molecular sieve C6 showed typical characteristic peaks of ZSM-5 molecular sieve, and the crystallite size of molecular sieve C6 was 520-880 nm.

[0076] Comparative Example 6

[0077] Compared with Example 4, the difference lies in the addition of crystallization aid B5 from Comparative Example 2 during the molecular sieve synthesis process, and the extended sealing treatment time to 36 hours. Specifically, the molecular sieve crystallization aid B5 prepared in Comparative Example 2 was added to the molecular sieve synthesis mother liquor for ZSM-5 molecular sieve synthesis. Specifically, 60 g of silica, 6.7 g of aluminum sulfate octadecylhydrate, 270 g of water, 20.3 g of tetrapropylammonium hydroxide, 2 g of sodium hydroxide, and 12 g of molecular sieve crystallization aid B5 were mixed evenly, and then treated in a sealed space at 160°C for 36 hours. After the treatment, the mixture was cooled, centrifuged, dried at 120°C for 10 hours, and calcined at 550°C for 5 hours to obtain molecular sieve C7. The XRD pattern of molecular sieve C7 showed typical characteristic peaks of ZSM-5 molecular sieve, and the crystallite size of molecular sieve C7 was 580-950 nm.

[0078] Comparative Example 7

[0079] Synthesis of molecular sieve crystallization aids:

[0080] 208.3 g of tetraethyl silicate, 6.7 g of aluminum sulfate octadechydrate, 360 g of water, 61 g of tetrapropylammonium hydroxide, and 63.6 g of organic compound 2 (the structural formula of organic compound 2 is...) Where R1, R3, R4 and R6 are phenyl, and R2 and R5 are methyl) are mixed evenly to obtain mixture A6. Then, mixture A6 is stirred in a closed space at 150°C for 48 hours. After the treatment, it is cooled to room temperature, filtered, washed and dried to obtain molecular sieve crystallization aid B6.

[0081] The crystals in molecular sieve crystallization aid B6 are in powder form with a size of 300-800 nm.

[0082] Synthesis of molecular sieves:

[0083] The molecular sieve crystallization aid B6 prepared above was added to the molecular sieve synthesis mother liquor to synthesize ZSM-5 molecular sieve, specifically as follows: 60 g of silica, 6.7 g of aluminum sulfate octadecylhydrate, 270 g of water, 20.3 g of tetrapropylammonium hydroxide, 2 g of sodium hydroxide and 20 g of molecular sieve crystallization aid B6 were mixed evenly, and then treated at 160 °C for 48 hours in a closed space. After the treatment, the mixture was cooled, centrifuged, dried at 120 °C for 10 hours and calcined at 550 °C for 5 hours to obtain molecular sieve C8. The XRD pattern of molecular sieve C8 showed typical characteristic peaks of ZSM-5 molecular sieve, and the crystallite size of molecular sieve C8 was 550-1050 nm.

[0084] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a molecular sieve crystallization aid, comprising the following steps: (a) A mixture A is obtained by contacting a silicon source, an aluminum source, water, organic matter 1, and organic matter 2; (b) Treating mixture A yields a molecular sieve crystallization aid; The organic compound 1 mentioned in step (a) is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, ethylamine, ethylenediamine, n-butylamine, butanediamine, hexamethyleneimine, piperidine, piperazine, and dicyclohexylamine; The structural formula of organic compound 2 mentioned in step (a) is: R1-R6 are each independently selected from methyl, ethyl, propyl or phenyl, and R1-R6 contain 4 to 6 phenyl groups; In step (a), the molar ratio of silicon source, aluminum source, water, and organic matter 1 is silicon source: aluminum source: water: organic matter 1 = 1:(0-0.05):(5-30):(0.1-1), where silicon source is calculated as SiO2 and aluminum source is calculated as Al2O3; the ratio of the mass of organic matter 2 to the total mass of silicon source, aluminum source, water, and organic matter 1 is (0.05-0.2):1, where silicon source is calculated as SiO2 and aluminum source is calculated as Al2O3. The treatment conditions described in step (b) are 60-85 ℃ sealed treatment for 4-24 hours.

2. The preparation method according to claim 1, characterized in that, The silicon source mentioned in step (a) is one or more of tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, and tetraphenyl silicate; And / or, the aluminum source is one or more of aluminum sulfate, aluminum isopropoxide, sodium aluminate, and boehmite; And / or, the organic compound 1 is one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, ethylamine, n-butylamine and hexamethyleneimine.

3. The preparation method according to claim 2, characterized in that, The silicon source mentioned in step (a) is one or more of tetraethyl silicate, tetrapropyl silicate, and tetraphenyl silicate; And / or, the aluminum source is one or more of aluminum sulfate and boehmite.

4. The molecular sieve crystallization aid obtained by the preparation method according to any one of claims 1-3.

5. The molecular sieve crystallization aid according to claim 4, characterized in that, The two-dimensional image of the crystals in the molecular sieve crystallization aid is rectangular. The length of the crystals is 5.0-18.0 nm, the width is 2.0-6.0 nm, and the length-to-width ratio is 1.5-3.

5.

6. The molecular sieve crystallization aid according to claim 5, characterized in that, The molecular sieve crystallization aid contains phenyl groups, with a phenyl content of 1.5%-15%.

7. The molecular sieve crystallization aid according to claim 6, characterized in that, The molecular sieve crystallization aid contains phenyl, with a phenyl content of 5%-15%.

8. The molecular sieve crystallization aid according to claim 5, characterized in that, Molecular sieve crystallization aids are suspensions under normal temperature and pressure conditions.

9. The use of the molecular sieve crystallization aid according to any one of claims 4-8 in the synthesis of molecular sieves.

10. The application according to claim 9, characterized in that, The molecular sieve crystallization aid is used in the synthesis of silicon-aluminum molecular sieves containing 10-membered ring structures or 12-membered ring structures.

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