Composition for preparing SSZ-39 molecular sieve and preparation method of SSZ-39 molecular sieve

Abstract

The invention provides a composition for preparing an SSZ-39 molecular sieve, a preparation method of SSZ-39 molecular sieve raw powder and a preparation method of the SSZ-39 molecular sieve. The composition comprises a silicon source, an aluminum source, a mineralizing agent, a template agent M, an AEI seed crystal and water. The composition for preparing the SSZ-39 molecular sieve provided by the invention does not contain raw materials with FAU structural units, such as USY and the like, and the use amount of the template agent is very low, so that the preparation cost of the SSZ-39 molecular sieve can be remarkably reduced, and the synthesis steps are simplified.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve preparation, and more specifically to compositions for preparing SSZ-39 molecular sieves, methods for preparing molecular sieve raw powders, and methods for preparing SSZ-39 molecular sieves. Background Technology

[0002] SSZ-39 molecular sieve is a small-pore silica-alumina molecular sieve with an AEI topology. Its basic structural unit is a double six-membered ring, which is connected by four-membered rings to form three-dimensional eight-membered ring channels and a special pear-shaped cage-like cavity. The channel size is 3.8 Å. The structural characteristics of SSZ-39 make it an excellent small-pore shape-selective molecular sieve catalyst, exhibiting excellent catalytic performance in reactions such as selective catalytic reduction of nitrogen oxides, partial oxidation of methane, and methanol-to-olefins.

[0003] The preparation process of SSZ-39 usually involves adding raw materials such as USY and NH4Y containing FAU structural units to an organic template agent and then converting them into crystals.

[0004] US5958370 first reported the use of FAU topological molecular sieves to transform SSZ-39 molecular sieves, which employed a variety of organic template agents in large quantities, ranging from 0.1 to 0.5 (molar ratio) of the silicon source.

[0005] CN113039158A discloses a method for preparing zeolite with AEI framework structure through solventless zeolite interconversion. The preparation method involves grinding and mixing FAU framework zeolite, sodium hydroxide, and AEI seed crystals, then adding an organic template agent to form a thick paste, and then crystallizing it.

[0006] CN112299438A discloses a method for preparing SSZ-39 molecular sieve, which synthesizes two types of gels. First, a gel containing USY is crystallized, and then a second gel containing USY is added for secondary crystallization. Finally, solid-liquid separation is performed, and the product is obtained by calcination.

[0007] US20180093257A1 discloses a method for preparing SSZ-39 with a high silicon-to-aluminum ratio. It uses USY with a high silicon-to-aluminum ratio as a raw material, supplemented with an organic template agent, to obtain SSZ-39 molecular sieves with a silicon-to-aluminum ratio (Si / Al) of 20-50, with a yield of over 30%.

[0008] CN110980756A discloses a method for preparing SSZ-39 molecular sieve using phosphorus-modified Y molecular sieve as raw material. The method involves first impregnating the Y molecular sieve with a phosphorus-containing solution, then calcining it to obtain phosphorus-doped Y molecular sieve. Next, deionized water, alkali source, template agent, and silicon source are mixed and stirred evenly according to the specified ratio. The phosphorus-doped Y molecular sieve is then added to prepare a sol. The sol is then transferred to a crystallization kettle for crystallization to obtain the product.

[0009] CN110785379A discloses a morpholine-based quaternary ammonium cation and the AEI-type zeolite prepared therefrom. The obtained AEI zeolite crystals are in the form of microplates. The preparation process mainly involves a crystallization reaction of silicon oxide, octahedral zeolite, a quaternary ammonium compound containing 2,4,4,6-tetramethylmorpholine cation, an alkali metal hydroxide, and water to obtain AEI zeolite crystals.

[0010] Currently, the synthesis cost of SSZ-39 mainly comes from two parts: firstly, the high cost of raw materials such as USY and NH4Y; and secondly, the large amount of organic template agent used. Generally, the molar ratio of organic template agent to silica in the raw materials is above 0.15, and in some cases even as high as 0.5. The future direction for SSZ-39 synthesis is to avoid using high-cost raw materials like USY and to minimize the amount of organic template agent used. However, existing synthesis techniques have not effectively reduced the cost of SSZ-39 molecular sieve synthesis. Summary of the Invention

[0011] In a first aspect, this application provides a composition for preparing SSZ-39 molecular sieve, the composition comprising a silicon source, an aluminum source, a mineralizing agent, a template agent M, AEI seed crystals, and water.

[0012] According to some embodiments of the present invention, the composition comprises a silicon source, an aluminum source, a mineralizer, a template agent M, an AEI seed crystal, and water.

[0013] According to some embodiments of the present invention, the silicon source is selected from silica gel, fumed silica, silica sol, tetraethyl orthosilicate, and any combination thereof.

[0014] According to some embodiments of the present invention, the aluminum source is selected from aluminum sulfate, aluminum nitrate, sodium aluminate, aluminum hydroxide, boehmite, and any combination thereof.

[0015] According to some embodiments of the present invention, the mineralizing agent is selected from sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia, and any combination thereof.

[0016] According to some embodiments of the present invention, the template agent is selected from N,N-dimethyl-3,5-dimethylpiperidine hydroxide, N,N-dimethyl-2,6-dimethylpiperidine hydroxide, N,N-diethyl-2,6-dimethylpiperidine hydroxide, N,N-diethyl-2-diethylpiperidine hydroxide, N-ethyl-N-methyl-2,6-dimethylpiperidine hydroxide, tetraethylphosphorus hydroxide, and any combination thereof.

[0017] According to some embodiments of the present invention, the AEI seed crystal is of the hydrogen form or sodium form, and the silicon-to-aluminum ratio (SiO2 / Al2O3) is preferably 10-50. In some embodiments, the silicon-to-aluminum molar ratio (SiO2 / Al2O3) of the AEI seed crystal is 15-40, preferably 15-35, for example 15, 20, 25, 30 or 35.

[0018] According to some embodiments of the present invention, the weight of the AEI seed crystal is 2-20% of the weight of the silicon source, preferably 4-15%. In some embodiments, the weight of the AEI seed crystal is 5%, 7.5%, 10%, or 14.6% of the weight of the silicon source.

[0019] According to some embodiments of the present invention, the mass ratio of the template agent M to the silicon source (based on SiO2) is (0.01-0.05):1. In this invention, seed crystals are primarily used as guiding agents, with the template agent serving as an auxiliary agent; therefore, the amount of template agent used can be relatively small.

[0020] According to some embodiments of the present invention, the molar ratio of silicon source (SiO2), aluminum source (Al2O3), mineralizer (Na2O), and water is 1:(0.01-0.1):(0.1-0.8):(5-20). According to some embodiments of the present invention, the molar ratio of silicon source (SiO2), aluminum source (Al2O3), mineralizer (Na2O), and water is 1:(0.01-0.08):(0.1-0.6):(5-20) or 1:(0.01-0.05):(0.1-0.6):(5-18). In some embodiments, the molar ratio of silicon source (SiO2), aluminum source (Al2O3), mineralizer (Na2O), and water is 1:(0.01-0.05):(0.15-0.5):(9-18).

[0021] According to some embodiments of the present invention, the water in the composition is deionized water.

[0022] In a second aspect, the present invention also provides a method for preparing SSZ-39 molecular sieve raw powder, which includes or consists of the following steps:

[0023] (1) The components in the composition described in the first aspect are mixed and aged to form a molecular sieve mother liquor;

[0024] (2) The molecular sieve mother liquor is crystallized, separated into solid and liquid, washed and dried in sequence to obtain the SSZ-39 molecular sieve raw powder.

[0025] According to some embodiments of the present invention, the crystallization temperature is 110℃-180℃, preferably 120℃-160℃. The crystallization described in the present invention is preferably a one-step crystallization.

[0026] According to some embodiments of the present invention, the crystallization time is 24h-120h, preferably 48h-72h.

[0027] According to some embodiments of the present invention, the crystallization is dynamic crystallization, preferably with a rotational speed of 10-30 rpm during the dynamic crystallization.

[0028] According to some embodiments of the present invention, the aging temperature is 15-40°C.

[0029] According to some embodiments of the present invention, the aging time is 1-4 hours, preferably 1.5-2.5 hours.

[0030] Thirdly, this application provides a method for preparing SSZ-39 molecular sieve, which includes or consists of the following steps: calcining the SSZ-39 molecular sieve raw powder prepared by the preparation method described in the second aspect.

[0031] According to some embodiments of the present invention, the calcination temperature is 500-700°C, preferably 530-600°C.

[0032] According to some embodiments of the present invention, the roasting time is 4-8 hours, preferably 5-6 hours.

[0033] According to some embodiments of the present invention, the SSZ-39 molecular sieve has a blocky morphology and a grain size of 1-2 μm.

[0034] Fourthly, this application provides an application of the SSZ-39 molecular sieve prepared by the preparation method described in the third aspect in the selective catalytic reduction of nitrogen oxides, partial oxidation of methane, or methanol to olefins.

[0035] The beneficial effects of this invention are:

[0036] The composition for preparing SSZ-39 molecular sieve provided by this invention does not contain raw materials with FAU structural units such as USY, and the amount of template agent used is very low, which can significantly reduce the preparation cost of SSZ-39 molecular sieve and simplify the synthesis steps. Attached Figure Description

[0037] Figure 1 These are the XRD diffraction patterns of the molecular sieves obtained in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0038] Figure 2 The crystal morphology of the molecular sieve obtained in Example 1 is shown. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and techniques have also been described in many publications.

[0040] Example 1

[0041] Weigh 0.8 g of mineralizing agent NaOH and 0.4 g of aluminum hydroxide (alumina content 64%) and add them to 5 g of deionized water. Stir and mix evenly. Then, add 10 g of silica sol (SiO2 content 40%), 1 g of template agent M, N,N-dimethyl-3,5-dimethylpiperidine hydroxide (35%), and 0.2 g of AEI seed crystals (SiO2 / Al2O3 = 18). Stir and mix evenly and age for 2 hours to obtain molecular sieve solution. The molar ratio of SiO2:Al2O3:Na2O:M:H2O in the solution is 1:0.038:0.15:0.033:9.71, and the AEI seed crystals are 5 wt%. Then, seal the solution in a synthesis vessel and dynamically crystallize at 160℃ (20 rpm) for 72 hours. Then, perform solid-liquid separation. The obtained solid is dried at 120℃ for 12 hours and calcined at 550℃ for 6 hours to obtain the finished molecular sieve.

[0042] The molecular sieve obtained in Example 1 was characterized for its crystal phase structure. Figure 1 Analysis was performed using a Rigaku Ultima IV X-ray powder diffractometer (Japan). A CuKα ray source was used. XRD diffraction patterns were obtained by scanning and recording under the following conditions: a nickel filter, a diffraction angle 2θ scanning range of 5–50°, an operating voltage of 35 kV, a current of 25 mA, and a scanning speed of 10° / min. The XRD diffraction patterns confirmed that the molecular sieve prepared in this invention is SSZ-39 molecular sieve.

[0043] The molecular sieve obtained in Example 1 was characterized for crystal morphology. Figure 2 The instrument uses a Japanese HITACHI S-4800 Scanning Electron Microcope with a resolution of 2nm@3KV.

[0044] Example 2

[0045] Weigh 0.8 g NaOH and 0.4 g sodium aluminate (alumina content 55%) and add them to 20 g deionized water. Stir and mix thoroughly. Then, add 6.2 g silica gel, 1 g N,N-dimethyl-3,5-dimethylpiperidine hydroxide (35%), and 0.25 g AEI seed crystals (SiO2 / Al2O3 = 18) sequentially. Stir and mix thoroughly, and age for 2 hours to obtain a molecular sieve solution. The molar ratio of SiO2:Al2O3:Na2O:M:H2O in the solution is 1:0.021:0.12:0.021:11.1, and the AEI seed crystals are 4.03 wt%. Then, seal the solution in a synthesis reactor and dynamically crystallize at 160℃ for 72 hours. Then, perform solid-liquid separation, dry at 120℃ for 12 hours, and calcine at 550℃ for 6 hours to obtain the finished molecular sieve. The molecular sieve obtained in this embodiment was characterized by its crystal phase structure. The XRD pattern was similar to that of Example 1, confirming that the finished molecular sieve prepared in this embodiment was SSZ-39 molecular sieve.

[0046] Example 3

[0047] Weigh 1.5 g NaOH and 0.15 g sodium aluminate (alumina content 55%) and add them to 5 g deionized water. Stir and mix thoroughly. Then, add 8.2 g silica sol (SiO2 content 40%), 0.5 g N,N-dimethyl-2,6-dimethylpiperidine hydroxide (35%), and 0.6 g AEI seed crystals (SiO2 / Al2O3 = 25). Stir and mix thoroughly, and age for 2 hours to obtain a molecular sieve solution. The molar ratio of SiO2:Al2O3:Na2O:M:H2O in the solution is 1:0.015:0.36:0.020:10.4, and the AEI seed crystals are 18.3 wt%. Then, seal the solution in a synthesis reactor and dynamically crystallize at 160℃ for 72 hours. Then, perform solid-liquid separation, dry at 120℃ for 12 hours, and calcine at 550℃ for 6 hours to obtain the finished molecular sieve. The molecular sieve obtained in this embodiment was characterized by its crystal phase structure. The XRD pattern was similar to that of Example 1, confirming that the finished molecular sieve prepared in this embodiment was SSZ-39 molecular sieve.

[0048] Example 4

[0049] Weigh 1.5 g NaOH and 0.2 g sodium aluminate (alumina content 55%) and add them to 15 g deionized water. Stir and mix thoroughly. Then, add 12 g tetraethyl orthosilicate, 1 g N,N-dimethyl-2,6-dimethylpiperidine hydroxide (35%), and 0.5 g AEI seed crystals (SiO2 / Al2O3 = 25). Stir and mix thoroughly, and age for 2 hours to obtain a molecular sieve solution. The molar ratio of SiO2:Al2O3:Na2O:M:H2O in the solution is 1:0.019:0.36:0.039:15.5, and the AEI seed crystals are 14.9 wt%. Then, seal the solution in a synthesis reactor and dynamically crystallize at 160℃ for 72 hours. Then, perform solid-liquid separation, dry at 120℃ for 12 hours, and calcine at 550℃ for 6 hours to obtain the finished molecular sieve. The molecular sieve obtained in this embodiment was characterized by its crystal phase structure. The XRD pattern was similar to that of Example 1, confirming that the finished molecular sieve prepared in this embodiment was SSZ-39 molecular sieve.

[0050] Example 5

[0051] Weigh 1.8 g NaOH and 0.5 g aluminum sulfate and add them to 15 g deionized water. Stir and mix thoroughly. Then, add 4 g silica gel, 1 g N,N-dimethyl-3,5-dimethylpiperidine hydroxide (35%), and 0.3 g AEI seed crystals (SiO2 / Al2O3 = 25). Stir and mix thoroughly, and age for 2 hours to obtain a molecular sieve solution. The molar ratio of SiO2:Al2O3:Na2O:M:H2O in the solution is 1:0.011:0.34:0.033:13.0, and the AEI seed crystals are 7.5 wt%. Then, seal the solution in a synthesis reactor and dynamically crystallize at 160℃ for 72 hours. Then, perform solid-liquid separation, dry at 120℃ for 12 hours, and calcine at 550℃ for 6 hours to obtain the finished molecular sieve. The molecular sieve obtained in this embodiment was characterized by its crystal phase structure. The XRD pattern was similar to that of Example 1, confirming that the finished molecular sieve prepared in this embodiment was SSZ-39 molecular sieve.

[0052] Example 6

[0053] Weigh 1.9 g NaOH and 0.5 g aluminum sulfate and add them to 20 g deionized water. Stir and mix thoroughly. Then, add 4 g silica, 1 g N,N-dimethyl-3,5-dimethylpiperidine hydroxide (35%), and 0.4 g AEI seed crystals (SiO2 / Al2O3 = 25). Stir and mix thoroughly, and age for 2 hours to obtain a molecular sieve solution. The molar ratio of SiO2:Al2O3:Na2O:M:H2O in the solution is 1:0.011:0.36:0.033:17.2, and the AEI seed crystals are 10.0 wt%. Then, seal the solution in a synthesis reactor and dynamically crystallize at 160℃ for 72 hours. Then, perform solid-liquid separation, dry at 120℃ for 12 hours, and calcine at 550℃ for 6 hours to obtain the finished molecular sieve. The molecular sieve obtained in this embodiment was characterized by its crystal phase structure. The XRD pattern was similar to that of Example 1, confirming that the finished molecular sieve prepared in this embodiment was SSZ-39 molecular sieve.

[0054] Example 7

[0055] Weigh 0.8 g NaOH and 1.8 g aluminum nitrate and add them to 10 g deionized water. Stir and mix thoroughly. Then, add 12 g tetraethyl orthosilicate, 1 g N,N-dimethyl-2,6-dimethylpiperidine hydroxide (35%), and 0.5 g AEI seed crystals (SiO2 / Al2O3 = 18). Stir and mix thoroughly, and age for 2 hours to obtain a molecular sieve solution. The molar ratio of SiO2:Al2O3:Na2O:M:H2O in the solution is 1:0.043:0.18:0.039:10.6, and the AEI seed crystals are 14.9 wt%. Then, seal the solution in a synthesis reactor and dynamically crystallize at 160 °C for 72 hours. Then, perform solid-liquid separation, dry at 120 °C for 12 hours, and calcine at 550 °C for 6 hours to obtain the finished molecular sieve. The molecular sieve obtained in this embodiment was characterized by its crystal phase structure. The XRD pattern was similar to that of Example 1, confirming that the finished molecular sieve prepared in this embodiment was SSZ-39 molecular sieve.

[0056] Example 8

[0057] Weigh 1.2 g NaOH and 2.5 g aluminum nitrate and add them to 10 g deionized water. Stir and mix thoroughly. Then, add 12 g silica sol (SiO2 content 40%), 1 g N,N-dimethyl-2,6-dimethylpiperidine hydroxide (35%), and 0.7 g AEI seed crystals (SiO2 / Al2O3 = 18). Stir and mix thoroughly, and age for 2 hours to obtain a molecular sieve solution. The molar ratio of SiO2:Al2O3:Na2O:M:H2O in the solution is 1:0.042:0.19:0.028:12.4, and the AEI seed crystals are 14.6 wt%. Then, seal the solution in a synthesis reactor and dynamically crystallize at 160℃ for 72 hours. Then, perform solid-liquid separation, dry at 120℃ for 12 hours, and calcine at 550℃ for 6 hours to obtain the finished molecular sieve. The molecular sieve obtained in this embodiment was characterized by its crystal phase structure. The XRD pattern was similar to that of Example 1, confirming that the finished molecular sieve prepared in this embodiment was SSZ-39 molecular sieve.

[0058] Comparative Example 1

[0059] The preparation process was the same as in Example 1, except that no organic template agent and AEI seed crystals were added. The molecular sieve of Comparative Example 1 was characterized for crystal phase structure ( Figure 1 The specific conditions are the same as in Example 1.

[0060] Comparative Example 2

[0061] The preparation process was the same as in Example 1, except that no organic template agent was added. The molecular sieve of Comparative Example 2 was characterized for crystal phase structure ( Figure 1 The specific conditions are the same as in Example 1.

[0062] Comparative Example 3

[0063] Example 1 involved the same preparation process as Example 1 with the addition of DMP, except that AEI seeds were not added and the amount of organic template agent added was 6 grams. The molecular sieve of Comparative Example 3 was characterized for its crystal structure. Figure 1 The specific conditions are the same as in Example 1.

[0064] Depend on Figure 1 As can be seen, the product of Example 1 of the present invention is SSZ-39 molecular sieve, the product of Comparative Example 1 is mordenite, the product of Comparative Example 2 is a mixed-phase molecular sieve of mordenite and SSZ-39, and the product of Comparative Example 3 is a mixed-phase molecular sieve of mordenite and P zeolite.

[0065] Figure 2 The SSZ-39 sample of Example 1 of this invention has a blocky morphology and a grain size of 1-2 μm.

[0066] The preferred 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 combinations of 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 composition for preparing SSZ-39 molecular sieve, comprising or consisting of a silicon source, an aluminum source, a mineralizer, a template agent M, AEI seed crystals and water.

2. The composition according to claim 1, characterized in that The silicon source is selected from silica gel, white carbon black, silica sol, tetraethyl orthosilicate and any combination thereof; and / or The aluminum source is selected from aluminum sulfate, aluminum nitrate, sodium aluminate, aluminum hydroxide, pseudo-boehmite and any combination thereof; and / or The mineralizer is selected from sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia water and any combination thereof; and / or The template agent is selected from N,N-dimethyl-3,5-dimethylpiperidinium hydroxide, N,N-dimethyl-2,6-dimethylpiperidinium hydroxide, N,N-diethyl-2,6-dimethylpiperidinium hydroxide, N,N-diethyl-2-diethylpiperidinium hydroxide, N-ethyl-N-methyl-2,6-dimethylpiperidinium hydroxide, tetraethylphosphonium hydroxide and any combination thereof.

3. The composition according to claim 1, characterized in that The AEI seed crystal is of hydrogen type or sodium type, and the silicon-aluminum ratio (SiO2 / Al2O3) is 10-40, preferably 15-35.

4. The composition according to claim 1, characterized in that The weight of the AEI seed crystal is 2-20% of the weight of the silicon source, preferably 4-15%.

5. The composition according to claim 1, characterized in that The molar ratio of the template M to the silicon source in terms of SiO2 is (0.01-0.05):1; and / or The molar ratio of silicon source as SiO2, aluminum source as Al2O3, mineralizer as Na2O and water is: SiO2:Al2O3:Na2O:H2O=1:(0.01-0.1):(0.1-0.8):(5-20), Preferably, SiO2:Al2O3:Na2O:H2O=1:(0.01-0.08):(0.1-0.6):(5-18).

6. A method for preparing SSZ-39 molecular sieve raw powder, comprising or consisting of the following steps: (1) mixing the components in the composition according to any one of claims 1 to 5 and aging them to form a molecular sieve mother solution; (2) The molecular sieve mother liquor is sequentially subjected to crystallization, solid-liquid separation, washing and drying to obtain the SSZ-39 molecular sieve raw powder.

7. The preparation method according to claim 6, characterized in that: The crystallization temperature is 110°C-180°C, preferably 120°C-160°C; and / or the crystallization time is 24h-120h, preferably 48h-72h.

8. The preparation method according to claim 6, characterized in that: The aging temperature is 15-40° C., and the aging time is 1-4 hours, preferably 1.5-2.5 hours.

9. A method for preparing SSZ-39 molecular sieve, comprising or consisting of the following steps: The SSZ-39 molecular sieve raw powder prepared by the preparation method according to any one of claims 6 to 8 is calcined, preferably, the calcination temperature is 500-700° C., preferably 530-600° C., and. or the calcination time is 4-8 hours, preferably 5-6 hours; Preferably, the SSZ-39 molecular sieve has a block-like morphology and a grain size of 1-2 um.

10. Use of the SSZ-39 molecular sieve prepared by the preparation method according to claim 9 in selective catalytic reduction of nitrogen oxides, partial oxidation of methane or methanol to olefins.

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