Preparation method and application of SAPO-34 / SAPO-5 composite molecular sieve

Abstract

The application provides a preparation method of SAPO-34 / SAPO-5 composite molecular sieve, the SAPO-34 / SAPO-5 composite molecular sieve and application. The preparation method of the SAPO-34 / SAPO-5 composite molecular sieve provided by the application comprises S1: subjecting a first mixture comprising a silicon source, an aluminum source, a phosphorus source, a first structure directing agent and water to a first crystallization treatment to obtain a first crystallization product; S2: mixing a second structure directing agent with the first crystallization product and then subjecting to a second crystallization treatment; wherein the first structure directing agent is selected from tetraethylammonium hydroxide and / or morpholine, and the second structure directing agent is selected from tetraethylammonium hydroxide and / or morpholine. When the SAPO-34 / SAPO-5 composite molecular sieve prepared by the application is used in a methanol-to-olefin reaction, the selectivity of C4 olefin in the methanol-to-olefin reaction can be effectively improved, and the SAPO-34 / SAPO-5 composite molecular sieve has a good industrial application prospect.

Description

Technical Field

[0001] This application belongs to the field of catalysts, specifically relating to a method for preparing SAPO-34 / SAPO-5 composite molecular sieves, SAPO-34 / SAPO-5 composite molecular sieves and their applications. Background Technology

[0002] SAPO molecular sieves were invented by Union Carbide Corporation (UCC). These sieves are aluminosilicate phosphate molecular sieves with pore sizes of approximately 0.4 nm. SAPO molecular sieves consist of a three-dimensional crystal structure composed of AlO4, SiO4, and PO4 tetrahedra sharing oxygen atoms. Within the pores of the crystal, Si... 4+ Partially replaces P 5+ Or Al 3+ It produces acidity. SAPO series molecular sieves possess excellent thermal and hydrothermal stability, moderate acidity, high specific surface area, and highly ordered microporous channels, making them widely used in modern petroleum processing industries. The most notable SAPO series molecular sieve is SAPO-34, which exhibits excellent catalytic performance in the methanol-to-olefins (MTO) reaction: methanol conversion reaches 100%; ethylene and propylene selectivity can exceed 70%; however, the selectivity for C4 olefins is typically below 10%.

[0003] C4 olefins refer to monoolefins containing four carbon atoms and a double bond, such as 1-butene, 2-butene, and isobutene. C4 olefins have a wide range of applications. They can be used to manufacture various chemical products such as synthetic rubber, plastics, and fibers, including styrene-butadiene rubber, nitrile rubber, and ethylene-propylene copolymers, which are widely used in the automotive tire, rubber product, and plastics industries. Furthermore, C4 olefins can also be used to synthesize pharmaceuticals; for example, butene can be used to prepare hormone drugs and medical-grade butenol. Therefore, C4 olefins play a vital role in the chemical and pharmaceutical fields as an important class of chemicals.

[0004] In conclusion, designing and synthesizing a molecular sieve that enhances the production of C4 olefins in the MTO reaction is of great significance as it can improve product value and increase the market competitiveness of enterprises. Summary of the Invention

[0005] To address the issue that existing SAPO-34 / SAPO-5 composite molecular sieves catalyze MTO reactions with a low proportion of C4 olefins in the products, this application provides a method for preparing SAPO-34 / SAPO-5 composite molecular sieves and the SAPO-34 / SAPO-5 composite molecular sieve itself.

[0006] Firstly, the preparation method of the SAPO-34 / SAPO-5 composite molecular sieve provided in this application includes:

[0007] S1: A first mixture comprising a silicon source, an aluminum source, a phosphorus source, a first structure directing agent, and water is subjected to a first crystallization treatment to obtain a first crystallization product;

[0008] S2: After mixing the second structure directing agent with the first crystallization product, a second crystallization treatment is performed;

[0009] The first structure directing agent is selected from tetraethylammonium hydroxide and / or morpholine, and the second structure directing agent is selected from tetraethylammonium hydroxide and / or morpholine.

[0010] In some embodiments, the first structure-directing agent is tetraethylammonium hydroxide, and the second structure-directing agent is morpholine.

[0011] In the synthesis of SAPO-34 / SAPO-5 composite molecular sieves, morpholine is miscible with water and has two hydrogen bond acceptors, making it a relatively strong Lewis base. It generates strong interactions with inorganic precursors, resulting in better crystal growth.

[0012] In some embodiments, the molar ratio of the first structure-directing agent to the second structure-directing agent is (0.1-15):1, for example, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.3:1, 2.5:1, 2.7:1, 2.9:1, 3:1, 3.3:1, 3. 5:1, 3.7:1, 3.9:1, 4:1, 4.3:1, 4.5:1, 4.7:1, 4.9:1, 5:1, 5.3:1, 5.5:1, 5.7:1, 5.9:1, 6:1, 6.3:1, 6.5:1, 6.7:1, 6.9:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, 10:1, 10.5:1, 11:1, 11.5:1, 12:1, 12.5:1, 13:1, 13.5:1, 14:1, 14.5:1, or any value between them.

[0013] In some embodiments, the molar ratio of the first structural directing agent to the second structural directing agent is (0.5-8):1. In some embodiments, the molar ratio of the first structural directing agent to the second structural directing agent is (0.8-5):1. In some embodiments, the molar ratio of the first structural directing agent to the second structural directing agent is (0.8-2):1.

[0014] In some embodiments, the aluminum source is Al2O3, and the molar ratio of the total molar amount of the first and second structure-directing agents to the aluminum source is (1-3):1, for example, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.3:1, 2.5:1, 2.7:1, 2.9:1, or any value between them. In some embodiments, the molar ratio of the total molar amount of the first and second structure-directing agents to the aluminum source is (1.5-2):1.

[0015] In some embodiments, the silicon source is selected from one or more of silica sol, silica, and tetraethyl orthosilicate.

[0016] In some embodiments, the phosphorus source is selected from one or more of phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, ammonium hydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, potassium hydrogen phosphate, sodium phosphate, disodium hydrogen phosphate, and sodium hydrogen phosphate.

[0017] In some embodiments, the aluminum source is selected from one or more of boehmite, aluminum isopropoxide, aluminum oxide, aluminum nitrate, aluminum chloride, and aluminum sulfate.

[0018] In some embodiments, the silicon source is SiO2 and the aluminum source is Al2O3, with a molar ratio of silicon to aluminum of (0.2-0.9):1, for example, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, or any value between them. In some embodiments, the molar ratio of silicon to aluminum is (0.3-0.6):1.

[0019] In some embodiments, the aluminum source is Al2O3, the phosphorus source is H3PO4, and the molar ratio of the phosphorus source to the aluminum source is (1.0-5.0):1, for example, 1.1:1, 1.3:1, 1.5:1, 1.7:1, 1.9:1, 2:1, 2.1:1, 2.3:1, 2.5:1, 2.7:1, 2.9:1, 3:1, 3.3:1, 3.5:1, 3.7:1, 3.9:1, 4:1, 4.3:1, 4.5:1, 4.7:1, 4.9:1, or any value between them. In some embodiments, the molar ratio of the phosphorus source to the aluminum source is (1.5-3.0):1.

[0020] In some embodiments, the aluminum source is Al2O3, and the molar ratio of water to aluminum source is (30-95):1, for example, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, or any value between them. In some embodiments, the molar ratio of water to aluminum source is (40-70):1.

[0021] In some embodiments, the aluminum source is calculated as Al2O3, the phosphorus source as H3PO4, the silicon source as SiO2, the first structure directing agent as R1, and the first structure directing agent as R2. Then the total raw material molar ratio is Al2O3:H3PO4:R1:R2:SiO2:H2O, which is (0.7-1.3):(1.5-3.0):(0.5-1.5):(0.5-1.5):(0.2-0.9):(40-95).

[0022] In some embodiments, in step S1, the first crystallization treatment is selected from rotational crystallization treatment. In some embodiments, the rotational speed is 5 rpm to 50 rpm, for example, 10 rpm, 20 rpm, 30 rpm or 40 rpm.

[0023] In some embodiments, the temperature of the first crystallization treatment is 120°C-200°C, for example, 130°C, 150°C, 170°C, 190°C, or 200°C. In some embodiments, the temperature of the crystallization treatment is 130°C-180°C.

[0024] In some embodiments, the first crystallization treatment time is 1 hour to 30 hours, for example, 5 hours, 10 hours, 15 hours, 20 hours, or 25 hours. In some embodiments, the first crystallization treatment time is 3 hours to 10 hours.

[0025] In some embodiments, in step S2, the second crystallization treatment is selected from rotational crystallization treatment. In some embodiments, the rotational speed is 5 rpm to 50 rpm, for example, 10 rpm, 20 rpm, 30 rpm or 40 rpm.

[0026] In some embodiments, the temperature of the second crystallization treatment is 150°C-250°C, for example, 170°C, 180°C, 200°C, 210°C, or 230°C. In some embodiments, the temperature of the second crystallization treatment is 190°C-210°C.

[0027] In some embodiments, the crystallization treatment time is 5h-70h, for example, 10h, 20h, 25h, 30h, 35h, 40h, 45h, 50h, 55h, 60h, or 65h. In some embodiments, the crystallization treatment time is 20h-50h.

[0028] In some embodiments, the preparation method further includes calcining the second crystallized product after treatment to obtain the SAPO-34 / SAPO-5 composite molecular sieve.

[0029] In some embodiments, the calcination temperature is 400°C-600°C, for example, 450°C, 500°C, or 550°C. In some embodiments, the calcination time is 3h-12h, for example, 6h, 9h, or 10h.

[0030] In some embodiments, the processing is a conventional post-processing step, such as separation, washing, and drying, wherein the separation, washing, and drying processes can be carried out using conventional methods, such as separation by centrifugation, washing by deionized water, and drying in an oven.

[0031] In some embodiments, the drying conditions may be: drying at 30-120°C for 2-30 hours.

[0032] Secondly, this application provides a SAPO-34 / SAPO-5 composite molecular sieve prepared using the preparation method described in the first aspect.

[0033] In some embodiments, the SAPO-5 molecular sieve content in the composite molecular sieve is 10%-50%, for example, 13%, 15%, 17%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 43%, 45%, 47%, or any value between them. In some embodiments, the SAPO-5 molecular sieve content in the composite molecular sieve is 10%-45%. In some embodiments, the SAPO-5 molecular sieve content in the composite molecular sieve is 25%-40%.

[0034] In some embodiments, the composite molecular sieve comprises molecular sieve particles having a cubical structure, wherein the molecular sieve particles include random nanoparticles.

[0035] In some embodiments, the longest side dimension of the cubic-like structure is 0.3 μm-10 μm, for example, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, or any value between them. In some embodiments, the longest side dimension of the cubic-like structure is 0.5 μm-5 μm.

[0036] In some embodiments, the nanoparticles have a particle size of 0.1 μm to 1.5 μm, for example, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or any value between them.

[0037] Thirdly, this application provides the application of the SAPO-34 / SAPO-5 composite molecular sieve prepared according to the preparation method described in the first aspect or the SAPO-34 / SAPO-5 composite molecular sieve described in the second aspect in the methanol-to-olefins reaction.

[0038] In some embodiments, the reaction conditions for the methanol-to-olefins reaction are: a reaction pressure of 0.1 MPaG-1.0 MPaG, a reaction temperature of 390℃-550℃, and a methanol feed weight hourly space velocity of 1 h⁻¹. -1 -50h -1 .

[0039] In some embodiments, the reaction pressure for methanol-to-olefins is 0.1 MPaG-1.0 MPaG; for example, 0.1 MPaG, 0.3 MPaG, 0.5 MPaG, 0.8 MPaG or 1.0 MPaG.

[0040] In some embodiments, the reaction temperature for methanol-to-olefins is 390°C-550°C; for example, 390°C, 400°C, 450°C, 480°C, 500°C, or 530°C.

[0041] In some embodiments, the methanol feed weight hourly space velocity (WHSV) for the methanol-to-olefins process is 1 h⁻¹. -1 -50h -1 For example, 1 hour -1 3h -1 5h -1 7h -1 10h -1 15h -1 20h -1 25h -1 30h -1 35h -1 40h -1 or 45h -1 .

[0042] In some embodiments, the total yield of C4 olefins in the methanol-to-olefins reaction is greater than or equal to 10 wt%, for example, greater than or equal to 15 wt%.

[0043] Compared with the prior art, this application has the following advantages:

[0044] (1) The preparation method of SAPO-34 / SAPO-5 composite molecular sieve in this application is simple and has low equipment requirements, which reduces the synthesis cost of SAPO-34 molecular sieve and has good industrial application prospects.

[0045] (2) When the SAPO-34 / SAPO-5 composite molecular sieve of this application is used in the methanol-to-olefins reaction, it can effectively improve the selectivity of C4 olefins in the methanol-to-olefins reaction and has a good industrial application prospect. Attached Figure Description

[0046] Figure 1 These are the XRD patterns of the SAPO-34 / SAPO-5 composite molecular sieves obtained in Examples 1-6 of this application.

[0047] Figure 2 These are SEM images of the SAPO-34 / SAPO-5 composite molecular sieve obtained in Example 1 of this application; the left image shows the overall appearance of the molecular sieve, and the right image is a magnified view of a part of it.

[0048] Figure 3 These are SEM images of the SAPO-34 / SAPO-5 composite molecular sieve obtained in Example 2 of this application; the left image shows the overall appearance of the molecular sieve, and the right image is a magnified view of a part of it.

[0049] Figure 4 These are SEM images of the SAPO-34 / SAPO-5 composite molecular sieve obtained in Example 3 of this application; the left image shows the overall appearance of the molecular sieve, and the right image is a magnified view of a part of it.

[0050] Figure 5 These are SEM images of the SAPO-34 / SAPO-5 composite molecular sieve obtained in Example 4 of this application; the left image shows the overall appearance of the molecular sieve, and the right image is a magnified view of a part of it.

[0051] Figure 6 These are SEM images of the SAPO-34 / SAPO-5 composite molecular sieve obtained in Example 5 of this application; the left image shows the overall appearance of the molecular sieve, and the right image is a magnified view of a part of it.

[0052] Figure 7 These are SEM images of the SAPO-34 / SAPO-5 composite molecular sieve obtained in Example 6 of this application; the left image shows the overall appearance of the molecular sieve, and the right image is a magnified view of a part of it.

[0053] Figure 8 This is the XRD pattern of the molecular sieve obtained in Comparative Example 1 of this application.

[0054] Figure 9 The images shown are SEM images of the molecular sieve obtained in Comparative Example 1 of this application; the left image shows the overall appearance of the molecular sieve, and the right image is a magnified view of a portion of the sieve.

[0055] Figure 10 This is the XRD pattern of the molecular sieve obtained in Comparative Example 2 of this application.

[0056] Figure 11 These are SEM images of the molecular sieve obtained in Comparative Example 2 of this application; the left image shows the overall appearance of the molecular sieve, and the right image is a magnified view of a part of the sieve.

[0057] Figure 12 This is the XRD pattern of the molecular sieve obtained in Comparative Example 3 of this application.

[0058] Figure 13 These are SEM images of the molecular sieve obtained in Comparative Example 3 of this application; the left image shows the overall appearance of the molecular sieve, and the right image is a magnified view of a part of the sieve.

[0059] Figure 14 This is the XRD pattern of the molecular sieve obtained in Comparative Example 4 of this application.

[0060] Figure 15 These are SEM images of the molecular sieve obtained in Comparative Example 4 of this application; the left image shows the overall appearance of the molecular sieve, and the right image is a magnified view of a part of it.

[0061] Figure 16 This is the XRD pattern of the molecular sieve obtained in Comparative Example 5 of this application.

[0062] Figure 17 These are SEM images of the molecular sieve obtained in Comparative Example 5 of this application; the left image shows the overall appearance of the molecular sieve, and the right image is a magnified view of a part of it. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and technologies have also been described in numerous publications.

[0064] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0065] In the context of this specification, including the following examples and comparative examples, XRD data were obtained using a Bruker AXSD8 Advance X-ray diffractometer (Germany) under Cu Kα radiation (40 kV, 40 mA). The test step size is 0.02, the step time is 12.6s, and the test 2θ range is 5-50°.

[0066] In the context of this specification, including the following examples and comparative examples, SEM images were obtained using a Japanese HITACHI S4800 field emission scanning electron microscope under test conditions of 3 kV and 10 μA.

[0067] Unless otherwise specified, the pressures mentioned in the following examples and comparative examples are gauge pressures, and % represents mass percentage.

[0068] The present application will be further described below with reference to the embodiments, but the embodiments do not limit the scope of protection of the present application.

[0069] Example 1

[0070] Silica sol (40 wt% SiO2), pseudoboehmite (70 wt% Al2O3), and phosphoric acid (85 wt% H3PO4) were used as silicon, aluminum, and phosphorus sources, respectively, with morpholine MOR as the first structure directing agent. The silicon, aluminum, phosphorus, and morpholine MOR were added to water and mixed to obtain a mixture. The molar ratio of the raw materials was Al2O3:H3PO4:MOR:SiO2:H2O of 1.0:2.0:1.0:0.3:55.

[0071] The mixture was crystallized at 160°C and 30 rpm for 5 hours, then the temperature was lowered to 25°C. Subsequently, a second structure-directing agent, tetraethylammonium hydroxide (TEAOH), was added, with a molar ratio of TEAOH to the aluminum source (based on Al₂O₃) of 1.0. The mixture was then crystallized at 200°C and 30 rpm for 48 hours.

[0072] After crystallization, the crystallized product was cooled, centrifuged, washed, dried at 100℃ for 6 hours, and calcined at 550℃ for 6 hours to obtain SAPO-34 / SAPO-5 composite molecular sieve.

[0073] The XRD pattern of the molecular sieve obtained in Example 1 is shown below. Figure 1 As shown, from Figure 1 It can be seen that the synthesized molecular sieve has the characteristic diffraction peaks of SAPO-34 and SAPO-5 molecular sieves. 2θ diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31°, while 2θ diffraction peaks belonging to SAPO-5 molecular sieve appear at 7.4°.

[0074] The mass fraction of SAPO-5 in the molecular sieve was calculated based on the peak intensities of the diffraction peaks at 7.4° and 9.5°: I(7.4°) / (I(7.4°)+I(9.5°))=21.1%.

[0075] The SEM image of the molecular sieve obtained in Example 1 is shown below. Figure 2 As shown, from Figure 2 It can be seen that the molecular sieve particles are cubic particles (traditional SAPO-34 morphology), with the longest side length being 2-5 μm; there are some irregular nanoparticles on the particles, with a particle size of 0.2-1.0 μm, which belong to SAPO-5 molecular sieve.

[0076] Example 2

[0077] Silica sol (40 wt% SiO2), pseudoboehmite (70 wt% Al2O3), and phosphoric acid (85 wt% H3PO4) were used as the silicon source, aluminum source, and phosphorus source, respectively, with tetraethylammonium hydroxide (TEAOH) as the first structure directing agent. The silicon source, aluminum source, phosphorus source, and TEAOH were added to water and mixed to obtain a mixture. The molar ratio of the raw materials was Al2O3:H3PO4:TEAOH:SiO2:H2O of 1.0:2.0:1.0:0.3:55.

[0078] The mixture was crystallized at 160°C and 30 rpm for 5 hours, then the temperature was lowered to 25°C. Subsequently, a second structure-directing agent, morpholine (MOR), was added at a molar ratio of 1.0 to the aluminum source (based on Al₂O₃). The mixture was then crystallized at 200°C and 30 rpm for 48 hours.

[0079] After crystallization, the crystallized product was cooled, centrifuged, washed, dried at 100℃ for 6 hours, and calcined at 550℃ for 6 hours to obtain SAPO-34 / SAPO-5 composite molecular sieve.

[0080] The XRD pattern of the molecular sieve obtained in Example 2 is shown below. Figure 1 As shown, from Figure 1 It can be seen that the synthesized molecular sieve has the characteristic diffraction peaks of SAPO-34 and SAPO-5 molecular sieves. 2θ diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31°, while 2θ diffraction peaks belonging to SAPO-5 molecular sieve appear at 7.4°.

[0081] The mass fraction of SAPO-5 in the molecular sieve was calculated based on the peak intensities of the diffraction peaks at 7.4° and 9.5°: I(7.4°) / (I(7.4°)+I(9.5°))=38.4%.

[0082] The SEM image of the molecular sieve obtained in Example 2 is shown below. Figure 3 As shown, from Figure 3 It can be seen that the molecular sieve particles are cubic particles (traditional SAPO-34 morphology), with the longest side length being 3-6 μm. There are some irregular nanoparticles on the particles, with a particle size of 0.1-1 μm, which belong to SAPO-5 molecular sieve.

[0083] Example 3

[0084] Silica sol (40 wt% SiO2), pseudoboehmite (70 wt% Al2O3), and phosphoric acid (85 wt% H3PO4) were used as the silicon source, aluminum source, and phosphorus source, respectively, with tetraethylammonium hydroxide (TEAOH) as the first structure directing agent. The silicon source, aluminum source, phosphorus source, and TEAOH were added to water and mixed to obtain a mixture. The molar ratio of the raw materials was Al2O3:H3PO4:TEAOH:SiO2:H2O of 1.0:2.0:1.0:0.4:55.

[0085] The mixture was crystallized at 160°C and 30 rpm for 5 hours, then the temperature was lowered to 25°C. Subsequently, a second structure-directing agent, morpholine (MOR), was added at a molar ratio of 1.0 to the aluminum source (based on Al₂O₃). The mixture was then crystallized at 200°C and 30 rpm for 48 hours.

[0086] After crystallization, the crystallized product was cooled, centrifuged, washed, dried at 100℃ for 6 hours, and calcined at 550℃ for 6 hours to obtain SAPO-34 / SAPO-5 composite molecular sieve.

[0087] The XRD pattern of the molecular sieve obtained in Example 3 is shown below. Figure 1 As shown, from Figure 1 It can be seen that the synthesized molecular sieve has the characteristic diffraction peaks of SAPO-34 and SAPO-5 molecular sieves. 2θ diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31°, while 2θ diffraction peaks belonging to SAPO-5 molecular sieve appear at 7.4°.

[0088] The mass fraction of SAPO-5 in the molecular sieve was calculated based on the peak intensities of the diffraction peaks at 7.4° and 9.5°: I(7.4°) / (I(7.4°)+I(9.5°))=26.8%.

[0089] The SEM image of the molecular sieve obtained in Example 3 is shown below. Figure 4 As shown, from Figure 4It can be seen that the molecular sieve particles are cubic particles (traditional SAPO-34 morphology), with the longest side length being 1-2 μm. There are some irregular nanoparticles on the particles, with a particle size of 0.2-0.8 μm, which belong to SAPO-5 molecular sieve.

[0090] Example 4

[0091] Silica sol (40 wt% SiO2), pseudoboehmite (70 wt% Al2O3), and phosphoric acid (85 wt% H3PO4) were used as the silicon source, aluminum source, and phosphorus source, respectively, with tetraethylammonium hydroxide (TEAOH) as the first structure directing agent. The silicon source, aluminum source, phosphorus source, and TEAOH were added to water and mixed to obtain a mixture. The molar ratio of the raw materials was Al2O3:H3PO4:TEAOH:SiO2:H2O of 1.0:2.0:0.5:0.3:55.

[0092] The mixture was crystallized at 160°C and 30 rpm for 5 hours, then the temperature was lowered to 25°C. Subsequently, a second structure-directing agent, morpholine (MOR), was added at a molar ratio of 1.5 to the aluminum source (based on Al₂O₃). The mixture was then crystallized at 200°C and 30 rpm for 48 hours.

[0093] After crystallization, the crystallized product was cooled, centrifuged, washed, dried at 100℃ for 6 hours, and calcined at 550℃ for 6 hours to obtain SAPO-34 / SAPO-5 composite molecular sieve.

[0094] The XRD pattern of the molecular sieve obtained in Example 4 is shown below. Figure 1 As shown, from Figure 1 It can be seen that the synthesized molecular sieve has the characteristic diffraction peaks of SAPO-34 and SAPO-5 molecular sieves. 2θ diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31°, while 2θ diffraction peaks belonging to SAPO-5 molecular sieve appear at 7.4°.

[0095] The mass fraction of SAPO-5 in the molecular sieve was calculated based on the peak intensities of the diffraction peaks at 7.4° and 9.5°: I(7.4°) / (I(7.4°)+I(9.5°))=26.5%.

[0096] The SEM image of the molecular sieve obtained in Example 4 is shown below. Figure 5 As shown, from Figure 5 It can be seen that the molecular sieve particles are cubic particles (traditional SAPO-34 morphology), with the longest side length being 1-4 μm. There are some irregular nanoparticles on the particles, with a particle size of 0.1-2.0 μm, which belong to SAPO-5 molecular sieve.

[0097] Example 5

[0098] Silica sol (40 wt% SiO2), pseudoboehmite (70 wt% Al2O3), and phosphoric acid (85 wt% H3PO4) were used as silicon, aluminum, and phosphorus sources, respectively, with tetraethylammonium hydroxide (TEAOH) as the first structure directing agent. The silicon, aluminum, and phosphorus sources were added to water and mixed to obtain a mixture. The molar ratio of the raw materials was Al2O3:H3PO4:TEAOH:SiO2:H2O of 1.0:2.0:1.5:0.3:55.

[0099] The mixture was crystallized at 160°C and 30 rpm for 5 hours, then the temperature was lowered to 25°C. Subsequently, a second structure-directing agent, morpholine (MOR), was added at a molar ratio of 0.5 to the aluminum source (based on Al₂O₃). The mixture was then crystallized at 200°C and 30 rpm for 48 hours.

[0100] After crystallization, the crystallized product was cooled, centrifuged, washed, dried at 100℃ for 6 hours, and calcined at 550℃ for 6 hours to obtain SAPO-34 / SAPO-5 composite molecular sieve.

[0101] The XRD pattern of the molecular sieve obtained in Example 5 is shown below. Figure 1 As shown, from Figure 1 It can be seen that the synthesized molecular sieves possess the characteristic diffraction peaks of SAPO-34 and SAPO-5 molecular sieves. 2θ diffraction peaks at 9.5°, 15.9°, 20.5°, 26°, and 31° belong to SAPO-34 molecular sieves. A diffraction peak at 7.4° belongs to SAPO-5 molecular sieves.

[0102] The mass fraction of SAPO-5 in the molecular sieve was calculated based on the peak intensities of the diffraction peaks at 7.4° and 9.5°: I(7.4°) / (I(7.4°)+I(9.5°))=16.7%.

[0103] The SEM image of the molecular sieve obtained in Example 5 is shown below. Figure 6 As shown, from Figure 6 It can be seen that the molecular sieve particles are cubic particles (traditional SAPO-34 morphology), with the longest side length being 2-5 μm. There are some irregular nanoparticles on the particles, with a particle size of 0.1-0.4 μm, which belong to SAPO-5 molecular sieve.

[0104] Example 6

[0105] Silica sol (40 wt% SiO2), pseudoboehmite (70 wt% Al2O3), and phosphoric acid (85 wt% H3PO4) were used as silicon, aluminum, and phosphorus sources, respectively, with tetraethylammonium hydroxide (TEAOH) as the first structure directing agent. The silicon, aluminum, and phosphorus sources were added to water and mixed to obtain a mixture. The molar ratio of the raw materials was Al2O3:H3PO4:TEAOH:SiO2:H2O of 1.0:2.0:0.8:0.3:75.

[0106] The mixture was crystallized at 160°C and 30 rpm for 5 hours, then the temperature was lowered to 25°C. Subsequently, a second structure-directing agent, morpholine (MOR), was added at a molar ratio of 1.2 to the aluminum source (Al₂O₃). The mixture was then crystallized at 200°C and 30 rpm for 48 hours.

[0107] After crystallization, the crystallized product was cooled, centrifuged, washed, dried at 100℃ for 6 hours, and calcined at 550℃ for 6 hours to obtain SAPO-34 / SAPO-5 composite molecular sieve.

[0108] The XRD pattern of the molecular sieve obtained in Example 6 is shown below. Figure 1 As shown, from Figure 1 It can be seen that the synthesized molecular sieve has the characteristic diffraction peaks of SAPO-34 and SAPO-5 molecular sieves. 2θ diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31°, while 2θ diffraction peaks belonging to SAPO-5 molecular sieve appear at 7.4°.

[0109] The mass fraction of SAPO-5 in the molecular sieve was calculated based on the peak intensities of the diffraction peaks at 7.4° and 9.5°: I(7.4°) / (I(7.4°)+I(9.5°))=10.9%.

[0110] The SEM image of the molecular sieve obtained in Example 6 is shown below. Figure 7 As shown, from Figure 7 It can be seen that the molecular sieve particles are cubic particles (traditional SAPO-34 molecular sieves) with a size of 1-4 μm. There are some irregular nanoparticles on the particles with a size of 0.1-0.8 μm, which belong to SAPO-5 molecular sieves.

[0111] Comparative Example 1

[0112] Silica sol (40 wt% SiO2), pseudoboehmite (70 wt% Al2O3), and phosphoric acid (85 wt% H3PO4) were used as silicon, aluminum, and phosphorus sources, respectively, with morpholine (MOR) and tetraethylammonium hydroxide (TEAOH) as organic template agents. The silicon, aluminum, and phosphorus sources, along with morpholine (MOR) and TEAOH, were added to water and mixed to obtain a mixture. The molar ratio of the raw materials was Al2O3:H3PO4:MOR:TEAOH:SiO2:H2O of 1.0:2.0:1.0:1.0:0.3:55.

[0113] The mixture was crystallized at 200°C and rotated at 30 rpm for 40 hours.

[0114] After crystallization, the crystallized product was cooled, centrifuged, washed, dried at 100℃ for 6 hours, and calcined at 550℃ for 6 hours to obtain the molecular sieve sample.

[0115] The XRD pattern of the molecular sieve obtained in Comparative Example 1 is shown below. Figure 8 As shown, from Figure 8 It can be seen that the synthesized molecular sieve only has the characteristic diffraction peaks of SAPO-34 molecular sieve. 2θ diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31°, while no diffraction peak belonging to SAPO-5 molecular sieve appears at 7.4°.

[0116] The SEM image of the molecular sieve obtained in Comparative Example 1 is shown below. Figure 9 As shown, from Figure 9 It can be seen that the molecular sieve particles are cubic nanoparticles with a size of 0.05-0.5μm.

[0117] Comparative Example 2

[0118] Silica sol (40 wt% SiO2), pseudoboehmite (70 wt% Al2O3), and phosphoric acid (85 wt% H3PO4) were used as the silicon source, aluminum source, and phosphorus source, respectively, with tetraethylammonium hydroxide (TEAOH) as the first structure directing agent. The silicon source, aluminum source, phosphorus source, and TEAOH were added to water and mixed to obtain a mixture. The molar ratio of the raw materials was Al2O3:H3PO4:TEAOH:SiO2:H2O of 1.0:2.0:1.0:0.3:55.

[0119] The mixture was crystallized at 160°C and 30 rpm for 5 hours, then the temperature was lowered to 25°C, and then the second structure directing agent, triethylamine (TEA), was added. The molar ratio of triethylamine (TEA) to aluminum source (calculated as Al2O3) was 1.0. The mixture was then crystallized at 200°C and 30 rpm for 48 hours.

[0120] After crystallization, the crystallized product was cooled, centrifuged, washed, dried at 100°C for 6 hours, and calcined at 550°C for 6 hours to obtain SAPO-34 molecular sieve.

[0121] The XRD pattern of the molecular sieve obtained in Comparative Example 2 is shown below. Figure 10 As shown, from Figure 10 It can be seen that the synthesized molecular sieve only has the characteristic diffraction peaks of SAPO-34 molecular sieve. 2θ diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31°, while no diffraction peak belonging to SAPO-5 molecular sieve appears at 7.4°.

[0122] The SEM image of the molecular sieve obtained in Comparative Example 2 is shown below. Figure 11 As shown, from Figure 11 It can be seen that the molecular sieve particles are cubic nanoparticles with a size of 0.2-0.7 μm.

[0123] Comparative Example 3

[0124] Silica sol (40 wt% SiO2), pseudoboehmite (70 wt% Al2O3), and phosphoric acid (85 wt% H3PO4) were used as silicon, aluminum, and phosphorus sources, respectively, with tetraethylammonium hydroxide (TEAOH) as the first structure directing agent. The silicon, aluminum, and phosphorus sources were added to water and mixed to obtain a mixture. The molar ratio of the raw materials was Al2O3:H3PO4:TEAOH:SiO2:H2O of 1.0:2.0:2.0:0.3:55.

[0125] The mixture was crystallized at 160°C and 30 rpm for 5 hours, then the temperature was lowered to 25°C, and a second structure directing agent, morpholine (MOR), was added. The molar ratio of morpholine (MOR) to the aluminum source (calculated as Al2O3) was 0.1. The mixture was then crystallized at 200°C and 30 rpm for 48 hours.

[0126] After crystallization, the crystallized product was cooled, centrifuged, washed, dried at 100°C for 6 hours, and calcined at 550°C for 6 hours to obtain SAPO-34 molecular sieve.

[0127] The XRD pattern of the molecular sieve obtained in Comparative Example 3 is shown below. Figure 12 As shown, from Figure 12 It can be seen that the synthesized molecular sieve only has the characteristic diffraction peaks of SAPO-34 molecular sieve. 2θ diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31°, while no diffraction peak belonging to SAPO-5 molecular sieve appears at 7.4°.

[0128] The SEM image of the molecular sieve obtained in Comparative Example 3 is shown below. Figure 13 As shown, from Figure 13 It can be seen that the molecular sieve particles are irregular nanoparticles with a size of 0.05-0.5μm.

[0129] Comparative Example 4

[0130] Silica sol (40 wt% SiO2), pseudoboehmite (70 wt% Al2O3), and phosphoric acid (85 wt% H3PO4) were used as the silicon source, aluminum source, and phosphorus source, respectively, with tetraethylammonium hydroxide (TEAOH) as the first structure directing agent. The silicon source, aluminum source, phosphorus source, and TEAOH were added to water and mixed to obtain a mixture. The molar ratio of the raw materials was Al2O3:H3PO4:TEAOH:SiO2:H2O of 1.0:2.0:1.0:0.3:55.

[0131] The mixture was crystallized at 160°C and 30 rpm for 5 hours, then the temperature was lowered to 25°C. Subsequently, a second structure directing agent, piperazine (PIPZ), was added at a molar ratio of 1.0 to the aluminum source (based on Al2O3). The mixture was then crystallized at 200°C and 30 rpm for 48 hours.

[0132] After crystallization, the crystallized product was cooled, centrifuged, washed, dried at 100℃ for 6 hours, and calcined at 550℃ for 6 hours to obtain SAPO-34 / SAPO-5 composite molecular sieve.

[0133] The XRD pattern of the molecular sieve obtained in Comparative Example 4 is shown below. Figure 14 As shown, from Figure 14 It can be seen that the synthesized molecular sieve has the characteristic diffraction peaks of SAPO-34 and SAPO-5 molecular sieves. 2θ diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31°, while 2θ diffraction peaks belonging to SAPO-5 molecular sieve appear at 7.4°.

[0134] The mass fraction of SAPO-5 in the molecular sieve was calculated based on the peak intensities of the diffraction peaks at 7.4° and 9.5°: I(7.4°) / (I(7.4°)+I(9.5°))=23.16%.

[0135] The SEM image of the molecular sieve obtained in Comparative Example 4 is shown below. Figure 15 As shown, from Figure 15 It can be seen that the molecular sieve has two morphologies: cubic particles, which are SAPO-34 molecular sieves with the longest side length of 2-4 μm, and hexagonal particles, which are SAPO-5 particles, which are broken and have a size of 0.3-3 μm.

[0136] Comparative Example 5

[0137] Silica sol (40 wt% SiO2), pseudoboehmite (70 wt% Al2O3), and phosphoric acid (85 wt% H3PO4) were used as the silicon source, aluminum source, and phosphorus source, respectively. Tetraethylammonium hydroxide (TEAOH) was used as the first structure directing agent, and morpholine (MOR) was used as the second structure directing agent. The molar ratio of the raw materials was Al2O3:H3PO4:MOR:TEAOH:SiO2:H2O of 1.0:2.0:1.0:1.0:0.3:55.

[0138] First, a silicon source and tetraethylammonium hydroxide (TEAOH) were added to water and mixed to obtain a mixture. The mixture was crystallized at 160°C and 30 rpm for 5 hours, and then the temperature was lowered to 25°C. Subsequently, an aluminum source, a phosphorus source, and a second structure-directing agent, morpholine (MOR), were added. The mixture was then crystallized at 200°C and 30 rpm for 48 hours.

[0139] After crystallization, the crystallized product was cooled, centrifuged, washed, dried at 100°C for 6 hours, and calcined at 550°C for 6 hours to obtain SAPO-34 molecular sieve.

[0140] The XRD pattern of the molecular sieve obtained in Comparative Example 5 is shown below. Figure 16 As shown, from Figure 16 It can be seen that the synthesized molecular sieve only has the characteristic diffraction peaks of SAPO-34 molecular sieve. 2θ diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31°, while no diffraction peak belonging to SAPO-5 molecular sieve appears at 7.4°.

[0141] The SEM image of the molecular sieve obtained in Comparative Example 5 is shown below. Figure 17 As shown, from Figure 17 It can be seen that the molecular sieve is a cubic nanoparticle, which is SAPO-34 molecular sieve with the longest side length being 0.2-1.5 μm.

[0142] Test case

[0143] The molecular sieves obtained in the above examples and comparative examples were used as catalysts in the methanol-to-olefins reaction at atmospheric pressure (0.1 MPa). The application test conditions were: WHSV = 6 h. -1 The reaction temperature is 460℃. Specific reaction performance details are listed in Table 1.

[0144] The diene yield is the sum of the ethylene and propylene yields. The conversion and selectivity of the products are calculated using gas chromatography based on CH2. C4 olefins include butene, etc.

[0145] Product yields are expressed by mass. Catalyst lifetime refers to the time it takes for the diene yield to reach its maximum; as the reaction continues, the diene yield will decrease rapidly, and byproducts will increase rapidly.

[0146] Table 1. Catalytic results of the molecular sieves obtained in the examples and comparative examples in methanol-to-olefins.

[0147]

[0148]

[0149] As can be seen from Table 1, the SAPO-34 / SAPO-5 composite molecular sieve prepared by the method of this application can improve the yield of C4 olefins in the methanol-to-olefins reaction, which is significantly higher than that of the comparative sample.

[0150] The preferred embodiments of this application have been described in detail above; however, this application is not limited thereto. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in this application and are all within the protection scope of this application.

Claims

1. A method for preparing a SAPO-34 / SAPO-5 composite molecular sieve, comprising: S1: A first mixture comprising a silicon source, an aluminum source, a phosphorus source, a first structure directing agent, and water is subjected to a first crystallization treatment to obtain a first crystallization product; S2: After mixing the second structure directing agent with the first crystallization product, a second crystallization treatment is performed; The first structure directing agent is selected from tetraethylammonium hydroxide and / or morpholine, and the second structure directing agent is selected from tetraethylammonium hydroxide and / or morpholine.

2. The preparation method according to claim 1, characterized in that, The first structure-directing agent is tetraethylammonium hydroxide, and the second structure-directing agent is morpholine.

3. The preparation method according to claim 1 or 2, characterized in that, The molar ratio of the first structure-directing agent to the second structure-directing agent is (0.1-15):1, preferably (0.5-8):1, more preferably (0.8-5):1, and even more preferably (0.8-2):

1.

4. The preparation method according to any one of claims 1-3, characterized in that, The aluminum source is Al2O3, and the molar ratio of the total molar amount of the first structural directing agent and the second structural directing agent to the aluminum source is (1-3):1, preferably (1.5-2):

1.

5. The preparation method according to any one of claims 1-4, characterized in that, The silicon source is selected from one or more of silica sol, silica, and tetraethyl orthosilicate; and / or The phosphorus source is selected from one or more of phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, ammonium hydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, potassium hydrogen phosphate, sodium phosphate, disodium hydrogen phosphate, and sodium hydrogen phosphate; and / or The aluminum source is selected from one or more of boehmite, aluminum isopropoxide, alumina, aluminum nitrate, aluminum chloride, and aluminum sulfate; and / or The silicon source is SiO2, and the aluminum source is Al2O3. The molar ratio of the silicon source to the aluminum source is (0.2-0.9):1, preferably (0.3-0.6):1; and / or The aluminum source is calculated as Al2O3, and the phosphorus source is calculated as H3PO4. The molar ratio of the phosphorus source to the aluminum source is (1.0-5.0):1, preferably (1.5-3.0):1; and / or The aluminum source is Al2O3, and the molar ratio of water to aluminum source is (30-95):1, preferably (40-70):

1.

6. The preparation method according to any one of claims 1-5, characterized in that, In step S1, the first crystallization treatment is selected from rotational crystallization treatment, preferably the rotation speed is 5 rpm to 50 rpm; and / or The temperature of the first crystallization treatment is 120℃-200℃, preferably 130℃-180℃; and / or The first crystallization treatment takes 1-30 hours, preferably 3-10 hours; and / or In step S2, the second crystallization treatment is selected from rotational crystallization treatment, preferably the rotation speed is 5 rpm to 50 rpm; and / or The temperature of the second crystallization treatment is 150℃-250℃, preferably 190℃-210℃; and / or The second crystallization treatment takes 5-70 hours, preferably 20-50 hours.

7. The preparation method according to any one of claims 1-6, characterized in that, The preparation method further includes calcining the second crystallized product after treatment to obtain the SAPO-34 / SAPO-5 composite molecular sieve. Preferably, the roasting temperature is 400℃-600℃, and the roasting time is 3h-12h.

8. A SAPO-34 / SAPO-5 composite molecular sieve prepared by the preparation method according to any one of claims 1-7; Preferably, the content of SAPO-5 molecular sieve in the composite molecular sieve is 10%-50%, more preferably 15%-40%; Preferably, the composite molecular sieve comprises molecular sieve particles with a cubic-like structure, and the molecular sieve particles include random nanoparticles. Preferably, the longest side dimension of the cubic-like structure is 0.3μm-10μm, more preferably 0.5μm-6μm. Preferably, the nanoparticles have a particle size of 0.1 μm to 1.5 μm.

9. The application of a SAPO-34 / SAPO-5 composite molecular sieve prepared by any one of claims 1-7 or the SAPO-34 / SAPO-5 composite molecular sieve of claim 8 in the methanol-to-olefins reaction.

10. The application according to claim 9, characterized in that, The reaction conditions for the methanol-to-olefins reaction are as follows: reaction pressure of 0.1 MPaG-1.0 MPaG, reaction temperature of 390℃-550℃, and methanol feed weight hourly space velocity of 1 h⁻¹. -1 -50h -1 , Preferably, in the methanol-to-olefins reaction, the total yield of C4 olefins is greater than or equal to 10 wt%, and more preferably greater than or equal to 15 wt%.

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