A method for synthesizing MSE molecular sieve

Abstract

The invention provides a method for synthesizing an MSE molecular sieve, and belongs to the technical field of molecular sieves. The invention uses tetramethylammonium hydroxide and tetrapropylammonium hydroxide as mixed template agents, stirs and mixes a silicon source, an aluminum source, sodium oxide, potassium oxide, a template agent and water, and then directly crystallizes, and then washes, dries and calcines to synthesize an MSE molecular sieve. The method for synthesizing an MSE molecular sieve provided by the invention does not require the addition of external crystal seeds, has easily available raw materials, is low in cost, and has simple steps, thus laying a foundation for further industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of molecular sieves, and in particular to a method for synthesizing an MSE molecular sieve. Background Art

[0002] Molecular sieves are porous materials with regular and uniform 3D channels composed of basic structural units of TO4 tetrahedrons (silicon-oxygen tetrahedrons, aluminum-oxygen tetrahedrons or phosphorus-oxygen tetrahedrons, etc.). Molecular sieves play an important role in the field of catalysis and green chemistry due to their uniform and regular microporous structure, excellent hydrothermal stability and high specific surface area. MSE molecular sieve is a large-pore silica-aluminum zeolite molecular sieve with a unique three-dimensional channel structure, which is formed by the intersection of a linear twelve-membered ring (0.64×0.68nm) channel and two independent curved ten-membered ring (0.52×0.58nm and 0.52×0.52nm) channels. Among them, four ten-membered rings are distributed in the straight channel of the twelve-membered ring, thus forming a 12×18-membered cylindrical supercage with only ten-membered ring windows. MSE has unique acid catalytic properties and shows excellent catalytic performance in reactions such as phenol hydroxylation, olefin epoxidation, aromatic alkylation and petroleum cracking. It is a very promising catalyst. MSE molecular sieves can also be used as catalyst carriers, such as preparing Ti-MSE catalysts for phenol hydroxylation and Fe-MSE catalysts for toluene benzylation.

[0003] In recent years, researchers have conducted relevant research on the synthesis route of MSE molecular sieves and obtained a series of results. According to the different organic structure-directing agents and strategies used in the synthesis process, they are named MCM-68, UZM-35, YNU-2, YNU-3, etc. At present, the commonly used template agents for the synthesis of MSE molecular sieves are mainly divided into N,N,N′,N′-tetraethyl-exo,exo-bicyclo[2.2.2]oct-7-ene-2,3,5,6-bipyrrole diiodide ammonium salt (TEBOP(I-)2) and dimethyldipropylammonium hydroxide. For example, the paper "Preparation of MSE molecular sieves and their application in alkylation reactions, Li Jintao, Nankai University" discloses a method for synthesizing MSE molecular sieves. The paper requires the synthesis of N,N,N′,N′-tetraethyl-exo, exo-bicyclo[2.2.2]oct-7-ene-2,3,5,6-bipyrrole diiodide ammonium salt (TEBOP(I-)2) template through three steps of amidation, carbon-based reduction, and quaternization. This technology not only has a complex preparation process, but also has expensive and difficult-to-obtain raw materials. The paper "Preparation, chemical modification and catalytic performance of Ti-MSE molecular sieves, Yin Jianyong, East China Normal University" uses dimethyldipropylammonium hydroxide as a template and introduces MCM-68 into the synthesis formula to assist crystallization to synthesize a molecular sieve with MSE structure. The template used in the paper, dimethyldipropylammonium hydroxide, is not easily available on the market and is expensive, and requires the addition of MSE seeds.

[0004] Therefore, the synthesis of MSE molecular sieves is still faced with the problems of few types of templates, complex preparation process, long cycle, high cost, and the need to add additional crystal seeds, which greatly limits the industrial application of this type of catalyst. Therefore, it is of great research significance to develop a new method for synthesizing MSE molecular sieves that is cheap and easy to obtain and does not require the addition of additional crystal seeds. Summary of the invention

[0005] In view of this, the present invention provides a method for synthesizing an MSE molecular sieve, the method comprising: firstly mixing a silicon source, an aluminum source, sodium oxide, potassium oxide, a template and water to obtain a mixed gel, then crystallizing the mixed gel at 160-180° C. for 144-240 hours, cooling after the crystallization, filtering, washing, drying and calcining to obtain an MSE molecular sieve;

[0006] The template agent consists of tetramethylammonium hydroxide and tetrapropylammonium hydroxide.

[0007] Furthermore, the mass ratio of the tetramethylammonium hydroxide to the tetrapropylammonium hydroxide is 1:3-4.

[0008] Furthermore, the silicon source includes silica sol, and the aluminum source includes aluminum sol.

[0009] Furthermore, the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the molar ratio of silicon oxide, aluminum oxide, sodium oxide, potassium oxide, tetramethylammonium hydroxide, tetrapropylammonium hydroxide and water in the mixed gel is 1:0.07-0.08:0.02-0.03:0.04-0.05:0.2-0.3:0.3-0.4:14-16.

[0010] Furthermore, the drying temperature is 100-120° C., and the drying time is 10-12 hours.

[0011] Furthermore, the calcination temperature is 500° C. and the calcination time is 6 to 8 hours.

[0012] Furthermore, the stirring temperature is room temperature.

[0013] The present invention also provides an MSE molecular sieve synthesized according to the method, and application of the MSE molecular sieve in preparing a Ti-MSE catalyst.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The invention uses cheap and readily available tetramethylammonium hydroxide and tetrapropylammonium hydroxide as mixed template agents, does not need to add external crystal seeds, stirs and mixes silicon source, aluminum source, alkali source, template agent and water, directly crystallizes, and then washes, dries and calcines to synthesize MSE molecular sieve.

[0016] The invention provides a novel template agent for synthesizing MSE molecular sieves, thereby solving the problems of high cost and difficulty in obtaining the template agent in the process of synthesizing MSE molecular sieves in the prior art.

[0017] The MSE molecular sieve synthesis method provided by the present invention has readily available raw materials, low cost and simple steps, thus laying a foundation for further industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a SEM image of the MSE molecular sieve prepared in Example 1 of the present invention.

[0019] Figure 2 This is a SEM image of the MSE molecular sieve prepared in Comparative Example 1 of the present invention.

[0020] Figure 3 This is a SEM image of the MSE molecular sieve prepared in Comparative Example 2 of the present invention.

[0021] Figure 4 This is a SEM image of the MSE molecular sieve prepared in Comparative Example 3 of the present invention.

[0022] Figure 5 This is a SEM image of the MSE molecular sieve prepared in Comparative Example 4 of the present invention.

[0023] Figure 6 This is a SEM image of the MSE molecular sieve prepared in Comparative Example 5 of the present invention. DETAILED DESCRIPTION

[0024] The invention provides a method for synthesizing an MSE molecular sieve, which comprises: firstly mixing a silicon source, an aluminum source, sodium oxide, potassium oxide, a template agent and water and stirring them uniformly to obtain a mixed gel, then crystallizing the mixed gel at 160-180° C. for 144-240 hours, cooling after the crystallization, filtering, washing with water, drying and calcining to obtain the MSE molecular sieve; the template agent is composed of tetramethylammonium hydroxide and tetrapropylammonium hydroxide.

[0025] In some embodiments of the present invention, the mass ratio of the tetramethylammonium hydroxide to the tetrapropylammonium hydroxide is 1:3-4. Preferably, the mass ratio of the tetramethylammonium hydroxide to the tetrapropylammonium hydroxide is 1:3.5-4.0.

[0026] In some embodiments of the present invention, the silicon source includes silica sol, and the aluminum source includes aluminum sol.

[0027] In some embodiments of the present invention, the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the molar ratio of silicon oxide, aluminum oxide, sodium oxide, potassium oxide, tetramethylammonium hydroxide, tetrapropylammonium hydroxide and water in the mixed gel is 1: 0.07-0.08: 0.02-0.03: 0.04-0.05: 0.2-0.3: 0.3-0.4: 14-16. Preferably, the molar ratio of each material in the mixed gel is silicon oxide: aluminum oxide: sodium oxide: potassium oxide: tetramethylammonium hydroxide: tetrapropylammonium hydroxide: water = 1: 0.075-0.08: 0.02-0.03: 0.045-0.05: 0.2-0.24: 0.33-0.38: 14.7-15.5.

[0028] In some embodiments of the present invention, the crystallization temperature is 160° C. and the crystallization time is 144 h.

[0029] In some embodiments of the present invention, the drying temperature is 100-120° C., and the drying time is 8-12 hours. Preferably, the drying temperature is 100° C., and the drying time is 8 hours.

[0030] In some embodiments of the present invention, the calcination temperature is 500° C., and the calcination time is 6 to 8 hours. Preferably, the calcination temperature is 500° C., and the calcination time is 6 hours.

[0031] In some embodiments of the present invention, the stirring temperature is room temperature.

[0032] The present invention also provides an MSE molecular sieve synthesized according to the method, and application of the MSE molecular sieve in preparing a Ti-MSE catalyst.

[0033] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0034] The experimental methods or test methods described in the following examples are conventional methods unless otherwise specified; the raw materials and auxiliary agents are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0035] The tetramethylammonium hydroxide (mass fraction of 25%) used in the following examples and comparative examples was purchased from Kent Catalytic Materials Co., Ltd. Tetrapropylammonium hydroxide (mass fraction of 25%) was purchased from Kent Catalytic Materials Co., Ltd. Sodium hydroxide (purity greater than 99%) was purchased from Dalian Shengjia Chemical. Potassium hydroxide (purity 85%) was purchased from Tianjin Komio Chemical Reagent Co., Ltd. Aluminum sol (aluminum oxide mass content of 20%) was purchased from Zhejiang Delixin Micronano Technology Co., Ltd. Alumina powder (aluminum oxide content of 70%) was purchased from Yangzhou Zhongtianli New Materials Co., Ltd. Silica sol (silicon oxide mass content of 30%) was purchased from Dalian Huihe Silicon Products Co., Ltd. White carbon black (silicon oxide mass content greater than 99.8%) was purchased from Jiangxi Black Cat Carbon Black Co., Ltd.

[0036] The catalyst scanning electron microscopy (SEM) characterization was measured by scanning electron microscope (Hitachi, SU5000).

[0037] Example 1

[0038] 0.23 g of sodium hydroxide, 0.62 g of potassium hydroxide, 26.13 g of deionized water, 7.10 g of tetramethylammonium hydroxide and 27.71 g of tetrapropylammonium hydroxide were mixed and stirred for 10 min, 3.72 g of aluminum sol was added and stirred for 1 h, 19.49 g of silica sol was added and stirred for 4 h to obtain a mixed gel; the mixed gel was loaded into a crystallization kettle, heated to 160°C, and kept warm for 144 h. After the insulation was completed, the temperature was lowered and the kettle was taken out, filtered and washed with water until neutral, dried at 100°C for 8 h, and calcined at 500°C for 6 h to obtain an MSE molecular sieve, which was recorded as MSE-1.

[0039] See the attached SEM photo of sample MSE-1 Figure 1 .

[0040] Example 2

[0041] Mix 0.20g sodium hydroxide, 0.63g potassium hydroxide, 26.00g deionized water, 7.52g tetramethylammonium hydroxide, and 27.15g tetrapropylammonium hydroxide and stir for 10 minutes, add 3.85g aluminum sol, and stir for 1 hour. Add 19.66g silica sol and stir for 4 hours to obtain a mixed gel. Put the mixed gel into a crystallization kettle, heat it to 160℃, and keep it warm for 144 hours. After the insulation is completed, cool it down and take it out of the kettle, filter it and wash it with water until it is neutral, dry it at 100℃ for 8 hours, and roast it at 500℃ for 6 hours to obtain MSE molecular sieve, which is recorded as MSE-2.

[0042] Example 3

[0043] Mix 0.21g sodium hydroxide, 0.58g potassium hydroxide, 26.09g deionized water, 7.49g tetramethylammonium hydroxide, and 28.11g tetrapropylammonium hydroxide and stir for 10min, add 3.81g aluminum sol and stir for 1h. Add 18.71g silica sol and stir for 4h to obtain a mixed gel. Put the mixed gel into a crystallization kettle, heat it to 160℃, keep it warm for 240h, cool it down after the insulation is completed, filter it and wash it with water until it is neutral, dry it at 100℃ for 8h, and roast it at 500℃ for 6h to obtain MSE molecular sieve, which is recorded as MSE-3.

[0044] Example 4

[0045] Mix 0.21g sodium hydroxide, 0.58g potassium hydroxide, 26.76g deionized water, 7.53g tetramethylammonium hydroxide, and 26.40g tetrapropylammonium hydroxide and stir for 10 minutes, add 3.81g aluminum sol, and stir for 1 hour. Add 19.70g silica sol and stir for 4 hours to obtain a mixed gel. Put the mixed gel into a crystallization kettle, heat it to 160℃, and keep it warm for 168 hours. After the insulation is completed, cool it down and take it out of the kettle, filter it and wash it with water until it is neutral, dry it at 100℃ for 8 hours, and roast it at 500℃ for 6 hours to obtain MSE molecular sieve, which is recorded as MSE-4.

[0046] Comparative Example 1

[0047] Mix 0.25g sodium hydroxide, 0.59g potassium hydroxide, 28.45g deionized water, and 30.17g tetrapropylammonium hydroxide and stir for 10 minutes, add 4.32g aluminum sol, and stir for 1 hour. Add 21.22g silica sol and stir for 4 hours to obtain a mixed gel. Put the mixed gel into a crystallization kettle, heat it to 160℃, and keep it warm for 168 hours. After the insulation is completed, cool it down and take it out of the kettle, filter it, wash it with water until it is neutral, dry it at 100℃ for 8 hours, and roast it at 500℃ for 6 hours to obtain MSE molecular sieve, which is recorded as MSE-D1.

[0048] See the attached SEM photo of sample MSE-D1 Figure 2 .

[0049] Comparative Example 2

[0050] Mix 0.29g sodium hydroxide, 0.89g potassium hydroxide, 38.27g deionized water, and 12.23g tetramethylammonium hydroxide and stir for 10 minutes, add 5.34 aluminum sol, and stir for 1 hour. Add 27.98g silica sol and stir for 4 hours to obtain a mixed gel. Put the mixed gel into a crystallization kettle, heat it to 160℃, and keep it warm for 168 hours. After the insulation is completed, cool it down and take it out of the kettle, filter it and wash it with water until it is neutral, dry it at 100℃ for 8 hours, and roast it at 500℃ for 6 hours to obtain MSE molecular sieve, which is recorded as MSE-D2.

[0051] See the attached SEM photo of sample MSE-D2 Figure 3 .

[0052] Comparative Example 3

[0053] Mix 0.17g sodium hydroxide, 0.50g potassium hydroxide, 21.74g deionized water, 7.33g tetramethylammonium hydroxide, and 35.98g tetrapropylammonium hydroxide and stir for 10 minutes, add 3.16g aluminum sol, and stir for 1 hour. Add 16.11g silica sol and stir for 4 hours to obtain a mixed gel. Put the mixed gel into a crystallization kettle, heat it to 160℃, and keep it warm for 168 hours. After the insulation is completed, cool it down and take it out of the kettle, filter it and wash it with water until it is neutral, dry it at 100℃ for 8 hours, and roast it at 500℃ for 6 hours to obtain MSE molecular sieve, which is recorded as MSE-D3.

[0054] See the attached SEM photo of sample MSE-D3 Figure 4 .

[0055] Comparative Example 4

[0056] Mix 0.22g sodium hydroxide, 0.63g potassium hydroxide, 27.10g deionized water, 7.31g tetramethylammonium hydroxide, and 28.54g tetrapropylammonium hydroxide and stir for 10 minutes, add 1.12g alumina powder (alumina content 70%), and stir for 1 hour. Add 20.08g silica sol and stir for 4 hours to obtain a mixed gel. Put the mixed gel into a crystallization kettle, heat it to 160°C, and keep it warm for 168 hours. After the insulation is completed, cool it down and take it out of the kettle, filter it and wash it with water until it is neutral, dry it at 100°C for 8 hours, and roast it at 500°C for 6 hours to obtain MSE molecular sieve, which is recorded as MSE-D4.

[0057] See attached for the SEM photo of sample MSE-D4 Figure 5 .

[0058] Comparative Example 5

[0059] Mix 0.24g sodium hydroxide, 0.69g potassium hydroxide, 29.66g deionized water, 9.60g tetramethylammonium hydroxide, and 33.92g tetrapropylammonium hydroxide and stir for 10 minutes, add 4.31g aluminum sol, and stir for 1 hour. Add 6.59g white carbon black (silicon oxide mass content is greater than 99.8%), stir for 4 hours, and obtain a mixed gel. Put the mixed gel into a crystallization kettle, heat it to 160°C, and keep it warm for 168 hours. After the insulation is completed, cool it down and take it out of the kettle, filter it, wash it with water until it is neutral, dry it at 100°C for 8 hours, and roast it at 500°C for 6 hours to obtain MSE molecular sieve, which is recorded as MSE-D5.

[0060] See the attached SEM photo of sample MSE-D5 Figure 6 .

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for synthesizing an MSE molecular sieve, characterized in that: The method comprises: firstly mixing and stirring a silicon source, an aluminum source, sodium oxide, potassium oxide, a template agent and water to obtain a mixed gel, then crystallizing the mixed gel at 160 to 180° C. for 144 to 240 hours, cooling after the crystallization, filtering, washing, drying and calcining to obtain an MSE molecular sieve; The template agent consists of tetramethylammonium hydroxide and tetrapropylammonium hydroxide.

2. The method for synthesizing the MSE molecular sieve according to claim 1, characterized in that: The mass ratio of the tetramethylammonium hydroxide to the tetrapropylammonium hydroxide is 1:3-4.

3. The method for synthesizing the MSE molecular sieve according to claim 1, characterized in that: The silicon source includes silica sol, and the aluminum source includes aluminum sol.

4. The method for synthesizing the MSE molecular sieve according to claim 1, characterized in that: The silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the molar ratio of silicon oxide, aluminum oxide, sodium oxide, potassium oxide, tetramethylammonium hydroxide, tetrapropylammonium hydroxide and water in the mixed gel is 1:0.07-0.08:0.02-0.03:0.04-0.05:0.2-0.3:0.3-0.4:14-16.

5. The method for synthesizing the MSE molecular sieve according to claim 1, characterized in that: The drying temperature is 100-120° C., and the drying time is 10-12 hours.

6. The method for synthesizing the MSE molecular sieve according to claim 1, characterized in that: The calcination temperature is 500° C. and the calcination time is 6 to 8 hours.

7. The method for synthesizing the MSE molecular sieve according to claim 1, characterized in that: The stirring temperature is room temperature.

8. An MSE molecular sieve synthesized according to the method according to any one of claims 1 to 7.

9. Use of the MSE molecular sieve synthesized by the method according to any one of claims 1 to 7 or the MSE molecular sieve according to claim 8 in the preparation of a Ti-MSE catalyst.

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