Structure-oriented composition for preparing SAPO-34 molecular sieve, SAPO-34 molecular sieve and preparation method of SAPO-34 molecular sieve
By using triethylamine and quaternary ammonium salt compounds as structural guides, the multi-stage pore SAPO-34 molecular sieve was prepared by hydrothermal synthesis method, which solved the problems of shape selection restriction and pore blockage of existing SAPO-34 catalysts, and achieved the High-efficiency catalytic effect and simplified synthesis process, suitable for methanol-to-olefin reaction.
Patent Information
- Application Number
- CN202310776381.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-28
- Publication Date
- 2025-01-03
AI Technical Summary
The existing SAPO-34 molecular sieve catalysts have shape selection restrictions and pore blockage problems in the methanol-to-olefin reaction, resulting in limited catalytic performance, and fewer preparation methods for multi-stage porous materials, and the existing synthesis methods are complex and costly.
Using triethylamine and/or tetraethylammonium hydroxide as the first structural guide agent, combining specific quaternary ammonium salt compounds as the second structural guide agent, and preparing cube-like multi-stage pore SAPO-34 through hydrothermal synthesis method Molecular sieve forms mesoporous and macroporous structures to improve catalytic performance.
The prepared SAPO-34 molecular sieve has good catalytic effect, and the pore size distribution is 10nm-1500nm, which simplifies the synthesis process and reduces costs. It is suitable for catalysis, adsorption and separation fields.
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Figure CN119240736A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of catalysts, and in particular relates to a structure-directed composition for preparing a SAPO-34 molecular sieve and a SAPO-34 molecular sieve and a preparation method thereof. Background Art
[0002] SAPO molecular sieve was invented by Union Carbide Corporation (UCC) of the United States. It is a silicoaluminophosphate molecular sieve with a pore size of about 0.4nm. SAPO molecular sieve is a three-dimensional crystal structure formed by AlO4, SiO4 and PO4 tetrahedrons sharing oxygen atoms. 4+ Partially replace P 5+ or Al 3+ The SAPO series of molecular sieves have good thermal and hydrothermal stability, moderate acidity, high specific surface area and highly ordered micropores, and are widely used in the modern petroleum processing industry. The most eye-catching is the SAPO-34 molecular sieve, which exhibits very good catalytic performance in the methanol to olefins (MTO) reaction: the conversion rate of methanol reaches 100%; the selectivity of ethylene and propylene can exceed 70%; C 5+ The content of components is low, and almost no aromatics are generated. However, the pore size of SAPO-34 molecular sieve is 0.38nm, which is an eight-membered ring pore, showing severe shape selection limitations. On the one hand, it hinders the contact between the raw material molecules and the active centers inside the pores, and on the other hand, it restricts the diffusion and mass transfer of reactants, intermediate transition products and final products. It is very easy for the pores to be blocked due to carbon deposition, resulting in the deactivation of the catalyst and limiting its catalytic performance.
[0003] So far, the methods for hydrothermal synthesis of hierarchical porous silicoaluminophosphate molecular sieves can be divided into post-treatment method, hard template method and soft template method. SAPO-34 molecular sieve has strict requirements on the conditions of post-treatment method, because the stability of silicoaluminophosphate molecular sieve is relatively poor compared with that of silicoaluminophosphate molecular sieve, and the conditions need to be precisely controlled when removing aluminum or silicon atoms with acid or alkali (Jiawei Zhong, Yingxu Wei, Chunshan Song and Zhongmin Liu, Catal. Sci. Technol., 2017, 7, 4905–4923), and the post-treatment method will cause a large amount of loss of the molecular sieve crystal structure, destroying the crystal structure and the acidity and alkalinity of the molecular sieve (X. Chen, A. Vicente, Z. Qin, V. Ruaux, J. P. Gilson and V. Valtchev, Chem. Commun., 2016, 52, 3512–3515.). Kaskel et al. added carbon materials (carbon nanotubes and carbon nanoparticles) during the synthesis of SAPO-34 molecular sieves, and eventually formed mesopores embedded in the molecular sieve crystals or running through the entire crystal particles in large SAPO-34 molecular sieve particles (F. Schmidt, S. Paasch, E. Brunner and S. Kaskel, Microporous Mesoporous Mater., 2012, 164, 214–221.). This method of synthesizing multi-level porous SAPO-34 molecular sieves using carbon materials as hard templates has a relatively complicated synthesis step, requiring the hard template to be synthesized first, and then the hard template must be removed by burning or other means after the synthesis of the multi-level porous molecular sieve. Danilina and Chen Lu et al. used a multifunctional long-chain organosilicon as the silicon source to hydrothermally synthesize SAPO-34 molecular sieves with a hierarchical pore structure (Chen Lu, Wang Runwei, Ding Shuang et al. Journal of Chemistry of Universities, 2010; 31(9): 1693-1696.); Liu Zhongmin et al. (J. Mater. Chem. A, 2015, 3, 5608-5616) used [3-(trimethoxysilyl)propyl]octadecyldimethylammonium chloride (TPOAC) as a surfactant to guide the synthesis of spherical SAPO-34 molecular sieves formed by lamellar stacking; Cui et al. (Cui Y, Zhang Q, He J, et al. Particuology, 2013; 11(4): 468-474.) used polyethylene glycol (PEG) as a mesoporous template to synthesize SAPO-34 molecular sieves with a hierarchical pore structure under hydrothermal conditions, and the size of the mesopores can be changed by adjusting the amount of PEG.
[0004] In summary, the preparation of hierarchical pore materials is currently a hot topic for scientific researchers, but there are still few existing methods for preparing hierarchical pore SAPO-34 molecular sieves. In view of this, it is still of great practical significance to develop a simple and low-cost synthetic hierarchical pore SAPO-34 molecular sieve preparation route. Summary of the invention
[0005] In view of the problems existing in the prior art, the present invention provides a structure-directed composition for preparing SAPO-34 molecular sieve and SAPO-34 molecular sieve and a preparation method thereof. The SAPO-34 molecular sieve prepared by the method provided by the present invention is a multi-level pore molecular sieve with a cubic morphology, which has a large number of mesopores and macropores inside, and can obtain a good catalytic effect when used in the methanol to olefin reaction.
[0006] In a first aspect, the structure-directing composition for preparing SAPO-34 molecular sieve provided by the present invention comprises a first structure-directing agent and a second structure-directing agent, wherein the first structure-directing agent comprises triethylamine and / or tetraethylammonium hydroxide, and the second structure-directing agent comprises a compound represented by formula I,
[0007]
[0008] In formula I, X is selected from halogen, and R is selected from C3-C10 straight or branched alkyl.
[0009] In the present invention, halogen is fluorine, chlorine, bromine or iodine.
[0010] In some embodiments, X is selected from bromine.
[0011] In some embodiments, R is selected from propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, n-heptyl, 2-methylhexyl, 3-methylhexyl, n-octyl, 2-methylheptyl, 3-methylheptyl, n-nonyl or n-decyl. In some embodiments, R is selected from C4-C8 straight chain alkyl.
[0012] In some embodiments, the second structure directing agent is selected from one or more of triethyl-n-butylammonium bromide, triethyl-n-hexylammonium bromide, and triethyl-n-octylammonium bromide.
[0013] In some embodiments, the molar ratio of the second structure directing agent to the first structure directing agent is (0.1-0.5): 1. In some embodiments, the molar ratio of the second structure directing agent to the first structure directing agent is 0.15: 1, 0.2: 1, 0.23: 1, 0.25: 1, 0.27: 1, 0.3: 1, 0.33: 1, 0.35: 1, 0.37: 1, 0.4: 1, 0.43: 1, 0.45: 1, 0.47: 1 or any value therebetween. In some embodiments, the molar ratio of the second structure directing agent to the first structure directing agent is (0.2-0.4): 1.
[0014] In a second aspect, the present invention provides a raw material for preparing a SAPO-34 molecular sieve, comprising an aluminum source, a phosphorus source, a silicon source and the structure-directed composition described in the first aspect.
[0015] In some embodiments, the SAPO-34 molecular sieve has a cube-like morphology. In some embodiments, the longest side length of the cube-like shape of the SAPO-34 molecular sieve is 1 μm-8 μm.
[0016] In some embodiments, the SAPO-34 molecular sieve has a multi-level pore structure, and the pore size distribution of the multi-level pores is 10 nm-1500 nm.
[0017] In some embodiments, the SAPO-34 molecular sieve contains mesopores / macropores, wherein the mesopores / macropores have a pore size distribution of 10 nm to 1500 nm. In some embodiments, the mesopores / macropores have a pore size distribution of 20 nm to 800 nm.
[0018] In some embodiments, the SAPO-34 molecular sieve can be used in the fields of catalysis, adsorption and separation.
[0019] In some embodiments, the aluminum source is calculated as Al2O3, and the molar ratio of the second structure directing agent to the aluminum source is (0.3-2.0):1. In some embodiments, the molar ratio of the second structure directing agent to the aluminum source is 0.35:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1.0:1, 1.05:1, 1.1:1, 1.15:1, 1.2:1, 1.25:1, 1.3:1, 1.35:1, 1.4:1, 1.55:1, 1.5:1, 1.55:1, 1.6:1, 1.65:1, 1.7:1, 1.75:1, 1.8:1, 1.85:1, 1.9:1, or any value therebetween. In some embodiments, the aluminum source is calculated as Al2O3, and the molar ratio of the second structure directing agent to the aluminum source is (0.4-1.5): 1. In some embodiments, the molar ratio of the second structure directing agent to the aluminum source is (0.6-1.2): 1. When the molar content of the second structure directing agent is too high, for example, higher than 2.0: 1, it will affect the formation of SAPO-34 crystals and guide the synthesis of excessive impurities; when it is too low, it will have little effect on SAPO-34 crystals and cannot significantly reduce the crystal size or produce a multi-level pore structure.
[0020] In some embodiments, the aluminum source is calculated as Al2O3, and the molar ratio of the first structure directing agent to the aluminum source is (1.5-5):1, for example, 2:1, 2.5:1, 3:1, 3.3:1, 3.5:1, 3.7:1, 4:1 or 4.5:1. In some embodiments, the molar ratio of the first structure directing agent to the aluminum source is (2.5-4):1.
[0021] In some embodiments, the aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, and the molar ratio of the silicon source to the aluminum source is (0.1-1.0):1, for example, 0.15:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1 or 0.9:1. In some embodiments, the molar ratio of the silicon source to the aluminum source is (0.2-0.5):1.
[0022] In some embodiments, the aluminum source is calculated as Al2O3, the phosphorus source is calculated as H3PO4, and the molar ratio of the phosphorus source to the aluminum source is (1-3):1, for example, 1.7:1, 2:1 or 2.3:1. In some embodiments, the molar ratio of the phosphorus source to the aluminum source is (1.5-2.5):1.
[0023] In some embodiments, the preparation raw material further comprises water. In some embodiments, the aluminum source is calculated as Al2O3, and the molar ratio of the water to the aluminum source is (30-90):1, for example, 35:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1 or 85:1. In some embodiments, the molar ratio of the water to the aluminum source is (40-80):1.
[0024] In some embodiments, the aluminum source is calculated as Al2O3, the phosphorus source is calculated as H3PO4, and the silicon source is calculated as SiO2, and the molar ratio of aluminum source:phosphorus source:second structure directing agent:second structure directing agent:silicon source:water is (0.7-1.5):(1.4-3.0):(0.4-1.5):(2-5):(0.2-0.9):(40-90).
[0025] In some embodiments, the aluminum source is selected from one or more of pseudo-boehmite, aluminum isopropoxide, aluminum oxide, aluminum nitrate, aluminum chloride, and aluminum sulfate.
[0026] 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.
[0027] In some embodiments, the silicon source is selected from one or more of silica sol, white carbon and tetraethyl orthosilicate.
[0028] In a third aspect, the present invention provides a method for preparing a SAPO-34 molecular sieve comprising:
[0029] S1: providing a mixture including an aluminum source, a phosphorus source, a silicon source, a first structure directing agent, a second structure directing agent and water;
[0030] S2: crystallizing the mixture in S1;
[0031] Wherein, the first structure directing agent comprises triethylamine and / or tetraethylammonium hydroxide, and the second structure directing agent comprises a compound represented by formula I,
[0032]
[0033] In formula I, X is selected from halogen, and R is selected from C3-C10 straight or branched alkyl.
[0034] In the present invention, by adopting a combination of a first structure directing agent and a quaternary ammonium salt structure directing agent shown in Formula I, the crystal size of the synthesized SAPO-34 molecular sieve can be reduced or a multi-level pore structure can be formed in the crystal, which is beneficial to the transmission of substances and improves the catalytic performance of the synthesized SAPO-34 molecular sieve.
[0035] In some embodiments, X is selected from bromine.
[0036] In some embodiments, R is selected from propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, n-heptyl, 2-methylhexyl, 3-methylhexyl, n-octyl, 2-methylheptyl, 3-methylheptyl, n-nonyl or n-decyl. In some embodiments, R is selected from C4-C8 straight chain alkyl.
[0037] In some embodiments, the second structure directing agent is selected from one or more of triethyl-n-butylammonium bromide, triethyl-n-hexylammonium bromide, and triethyl-n-octylammonium bromide.
[0038] In some embodiments, the molar ratio of the second structure directing agent to the first structure directing agent is (0.1-0.5): 1. In some embodiments, the molar ratio of the second structure directing agent to the first structure directing agent is 0.15: 1, 0.2: 1, 0.23: 1, 0.25: 1, 0.27: 1, 0.3: 1, 0.33: 1, 0.35: 1, 0.37: 1, 0.4: 1, 0.43: 1, 0.45: 1, 0.47: 1 or any value therebetween. In some embodiments, the molar ratio of the second structure directing agent to the first structure directing agent is (0.2-0.4): 1.
[0039] In some embodiments, the aluminum source is calculated as Al2O3, and the molar ratio of the second structure directing agent to the aluminum source is (0.3-2.0):1. In some embodiments, the molar ratio of the second structure directing agent to the aluminum source is 0.35:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1.0:1, 1.05:1, 1.1:1, 1.15:1, 1.2:1, 1.25:1, 1.3:1, 1.35:1, 1.4:1, 1.55:1, 1.5:1, 1.55:1, 1.6:1, 1.65:1, 1.7:1, 1.75:1, 1.8:1, 1.85:1, 1.9:1, or any value therebetween. In some embodiments, the aluminum source is calculated as Al2O3, and the molar ratio of the second structure directing agent to the aluminum source is (0.4-1.5): 1. In some embodiments, the molar ratio of the second structure directing agent to the aluminum source is (0.6-1.2): 1. When the molar content of the second structure directing agent is too high, for example, higher than 2.0: 1, it will affect the formation of SAPO-34 crystals and guide the synthesis of excessive impurities; when it is too low, it will have little effect on SAPO-34 crystals and cannot significantly reduce the crystal size or produce a multi-level pore structure.
[0040] In some embodiments, the aluminum source is calculated as Al2O3, and the molar ratio of the first structure directing agent to the aluminum source is (1.5-5):1, for example, 2:1, 2.5:1, 3:1, 3.3:1, 3.5:1, 3.7:1, 4:1 or 4.5:1. In some embodiments, the molar ratio of the first structure directing agent to the aluminum source is (2.5-4):1.
[0041] In some embodiments, the aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, and the molar ratio of the silicon source to the aluminum source is (0.1-1.0):1, for example, 0.15:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1 or 0.9:1. In some embodiments, the molar ratio of the silicon source to the aluminum source is (0.2-0.5):1.
[0042] In some embodiments, the aluminum source is calculated as Al2O3, the phosphorus source is calculated as H3PO4, and the molar ratio of the phosphorus source to the aluminum source is (1-3):1, for example, 1.7:1, 2:1 or 2.3:1. In some embodiments, the molar ratio of the phosphorus source to the aluminum source is (1.5-2.5):1.
[0043] In some embodiments, the aluminum source is calculated as Al2O3, and the molar ratio of the water to the aluminum source is (30-90):1, for example, 35:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1 or 85:1. In some embodiments, the molar ratio of the water to the aluminum source is (40-80):1.
[0044] In some embodiments, the aluminum source is calculated as Al2O3, the phosphorus source is calculated as H3PO4, and the silicon source is calculated as SiO2, and the molar ratio of aluminum source:phosphorus source:second structure directing agent:second structure directing agent:silicon source:water is (0.7-1.5):(1.4-3.0):(0.4-1.5):(2-5):(0.2-0.9):(40-90).
[0045] In some embodiments, the aluminum source is selected from one or more of pseudo-boehmite, aluminum isopropoxide, aluminum oxide, aluminum nitrate, aluminum chloride, and aluminum sulfate.
[0046] 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.
[0047] In some embodiments, the silicon source is selected from one or more of silica sol, white carbon and tetraethyl orthosilicate.
[0048] In some embodiments, the crystallization process is performed under stirring. In some embodiments, the stirring speed is 5 rpm to 50 rpm, for example, 10 rpm, 15 rpm, 20 rpm, 25 rpm, 30 rpm, 35 rpm, 40 rpm or 45 rpm.
[0049] In some embodiments, the crystallization process includes a first crystallization process, a second crystallization process, and a third crystallization process performed sequentially.
[0050] In some embodiments, the temperature of the first crystallization treatment is 120° C.-160° C., for example, 130° C., 140° C. or 150° C. In some embodiments, the time of the first crystallization treatment is 3 h-12 h, for example, 4 h, 6 h, 8 h or 10 h.
[0051] In some embodiments, the temperature of the second crystallization treatment is 190° C.-210° C., for example, 195° C., 200° C. or 205° C. In some embodiments, the time of the second crystallization treatment is 20 h-60 h, for example, 30 h, 40 h or 5 h.
[0052] In some embodiments, the temperature of the third crystallization treatment is 100° C.-150° C., for example, 110° C., 120° C., 130° C. or 140° C. In some embodiments, the time of the third crystallization treatment is 5 h-20 h, for example, 8 h, 10 h, 12 h, 14 h, 16 h or 18 h.
[0053] In some embodiments, conventional post-processing steps such as separation, washing and drying may be used after crystallization, wherein the separation, washing and drying processes may be carried out by conventional methods, such as separation may be carried out by centrifugal separation, washing may be carried out by deionized water, and drying may be carried out in an oven. For example, the drying conditions are: drying at 30° C.-120° C. for 2 h-20 h.
[0054] In some embodiments, the method further comprises calcining the product after post-treatment after crystallization. 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 3 h-12 h, for example, 4 h, 6 h, 8 h or 10 h.
[0055] In some embodiments, the present invention also provides a SAPO-34 molecular sieve prepared by the preparation method described in the third aspect.
[0056] In some embodiments, the SAPO-34 molecular sieve has a cube-like morphology. In some embodiments, the longest side length of the cube-like shape of the SAPO-34 molecular sieve is 1 μm-8 μm.
[0057] In some embodiments, the SAPO-34 molecular sieve contains mesopores / macropores, wherein the mesopores / macropores have a pore size distribution of 10 nm to 1500 nm. In some embodiments, the mesopores / macropores have a pore size distribution of 20 nm to 800 nm.
[0058] In some embodiments, the SAPO-34 molecular sieve can be used in the fields of catalysis, adsorption and separation.
[0059] In a fourth aspect, the present invention provides use of the SAPO-34 molecular sieve described in the second aspect or the SAPO-34 molecular sieve prepared by the preparation method described in the third aspect in a methanol to olefin reaction.
[0060] In some embodiments, the reaction conditions of the methanol to olefins reaction are: reaction pressure is atmospheric pressure-1.0 MPa, reaction temperature is 390°C-515°C, methanol feed weight space velocity is 1h -1 -100h -1 .
[0061] Compared with the prior art, the present invention has the following advantages:
[0062] 1. The SAPO-34 molecular sieve prepared by the present invention has a cubic morphology, and the pore size distribution of mesopores / macropores is 10nm-1500nm, and can obtain a good catalytic effect when used in the methanol to olefin reaction.
[0063] 2. The preparation method of the SAPO-34 molecular sieve of the present invention is simple, has low requirements on equipment, and has high product yield, so the present invention has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0064] Figure 1 1 is the XRD diagram of the SAPO-34 molecular sieve obtained in Examples 1-4 of the present invention.
[0065] Figure 2 This is a SEM image of the SAPO-34 molecular sieve obtained in Example 1 of the present invention; the left image is the overall appearance of the molecular sieve, and the right image is a partial enlarged image.
[0066] Figure 3 This is a SEM image of the SAPO-34 molecular sieve obtained in Example 2 of the present invention; the left image is the overall appearance of the molecular sieve, and the right image is a partial enlarged image.
[0067] Figure 4 This is a SEM image of the SAPO-34 molecular sieve obtained in Example 3 of the present invention; the left image is the overall appearance of the molecular sieve, and the right image is a partial enlarged image.
[0068] Figure 5 This is a SEM image of the SAPO-34 molecular sieve obtained in Example 4 of the present invention; the left image is the overall appearance of the molecular sieve, and the right image is a partial enlarged image.
[0069] Figure 6 This is the XRD pattern of the molecular sieve obtained in Example 5.
[0070] Figure 7 This is a SEM image of the molecular sieve obtained in Example 5; the left image is the overall appearance of the molecular sieve, and the right image is a partial enlarged image.
[0071] Figure 8 This is the XRD pattern of the molecular sieve obtained in Example 6.
[0072] Fig. 9 This is a SEM image of the molecular sieve obtained in Example 6; the left image is the overall appearance of the molecular sieve, and the right image is a partial enlarged image.
[0073] Fig.10 This is the XRD pattern of the molecular sieve obtained in Example 7.
[0074] Fig.11This is a SEM image of the molecular sieve obtained in Example 7; the left image is the overall appearance of the molecular sieve, and the right image is a partial enlarged image.
[0075] Fig.12 The XRD pattern of the molecular sieve obtained in Example 8 is
[0076] Fig.13 This is a SEM image of the molecular sieve obtained in Example 8; the left image is the overall appearance of the molecular sieve, and the right image is a partial enlarged image
[0077] Fig.14 This is the XRD diagram of the molecular sieve obtained in Comparative Example 1.
[0078] Fig.15 This is the SEM image of the molecular sieve obtained in Comparative Example 1. DETAILED DESCRIPTION
[0079] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and drawings. The specific embodiments described herein are only used to explain the present invention and are not intended to constitute any limitation to the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts of the present disclosure. Such structures and technologies are also described in many publications.
[0080] The endpoints and any values of the ranges disclosed in this article 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 each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.
[0081] In the context of this specification, including in the following examples and comparative examples, XRD data were measured using a German Bruker AXS D8 Advance X-ray diffractometer, and the test conditions were 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°.
[0082] In the context of this specification, including in the following examples and comparative examples, SEM images were obtained by a Japanese HITACHI S4800 field emission scanning electron microscope, and the test conditions were 3KV and a current of 10μA.
[0083] In the context of this specification, including the following examples and comparative examples, the pore volume and specific surface area of the molecular sieve are measured by nitrogen physical adsorption and desorption method (BET method): the nitrogen physical adsorption and desorption isotherm of the molecular sieve is measured by a physical adsorption instrument (Micromeritics TriStar 3000 physical adsorption instrument), and then calculated by the BET equation and t-plot equation. The experimental conditions are: the measurement temperature is 75K, and the molecular sieve is vacuum pretreated at 350°C for 4 hours before the measurement.
[0084] The present invention will be further described below in conjunction with examples, but the examples do not limit the protection scope of the present invention.
[0085] Example 1
[0086] Silica sol (40 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) were used as silicon source, aluminum source and phosphorus source respectively, and triethylamine TEA was used as a structure directing agent. Add into water and mix to obtain a mixture, the molar ratio of raw materials is Al2O3:H3PO4: auxiliary structure directing agent C4: structure directing agent: SiO2:H2O is 1.0:2.0:0.75:3.3:0.3:72.
[0087] The mixture was crystallized at 150°C at 30 rpm for 6 hours, then the temperature was raised to 200°C and crystallized for 48 hours, then the temperature was lowered to 120°C and crystallized for 6 hours.
[0088] After the crystallization is completed, the crystallized product is cooled, centrifuged, washed, dried at 100° C. for 6 hours, and calcined at 550° C. for 6 hours to obtain SAPO-34 molecular sieve.
[0089] The XRD spectrum of the sample is as follows Figure 1 As shown, from Figure 1 It can be seen that the synthesized molecular sieve has characteristic diffraction peaks of SAPO-34 molecular sieve, and diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31° at 2θ.
[0090] The SEM images of the samples are shown in Figure 2 As shown, from Figure 2 It can be seen that the molecular sieve has a cubic morphology, a particle size of 1 to 3 μm, and a multi-level pore structure on the particles.
[0091] The pore size distribution of the molecular sieve is 20 nm to 800 nm, and other properties are shown in Table 2.
[0092] Example 2
[0093] Silica sol (40 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) were used as silicon source, aluminum source and phosphorus source respectively, and triethylamine TEA was used as a structure directing agent. Add into water and mix to obtain a mixture, the molar ratio of raw materials is Al2O3:H3PO4: auxiliary structure directing agent C6: structure directing agent: SiO2:H2O is 1.0:2.0:0.75:3.2:0.3:72.
[0094] The mixture was crystallized at 150°C at 30 rpm for 6 hours, then the temperature was raised to 200°C and crystallized for 48 hours, then the temperature was lowered to 120°C and crystallized for 6 hours.
[0095] After the crystallization is completed, the crystallized product is cooled, centrifuged, washed, dried at 100° C. for 6 hours, and calcined at 550° C. for 6 hours to obtain SAPO-34 molecular sieve.
[0096] The XRD spectra of the samples are shown in Figure 1 ,from Figure 1 It can be seen that the diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31° of 2θ.
[0097] The SEM images of the samples are shown in Figure 3 As shown, from Figure 3 It can be seen that the molecular sieve has a cubic morphology and a particle size of 2 to 5 μm.
[0098] The pore size distribution of the molecular sieve is 100 nm to 1500 nm. Other properties are shown in Table 2.
[0099] Example 3
[0100] Silica sol (40 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) were used as silicon source, aluminum source and phosphorus source respectively, and triethylamine TEA was used as a structure directing agent. Add into water and mix to obtain a mixture, the molar ratio of raw materials is Al2O3:H3PO4: auxiliary structure directing agent C8: structure directing agent: SiO2:H2O is 1.0:2.0:0.75:3.2:0.3:72.
[0101] The mixture was crystallized at 150°C at 30 rpm for 6 hours, then the temperature was raised to 200°C and crystallized for 48 hours, then the temperature was lowered to 120°C and crystallized for 6 hours.
[0102] After the crystallization is completed, the crystallized product is cooled, centrifuged, washed, dried at 100° C. for 6 hours, and calcined at 550° C. for 6 hours to obtain SAPO-34 molecular sieve.
[0103] The XRD spectra of the samples are shown in Figure 1 ,from Figure 1 It can be seen that the diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31° of 2θ.
[0104] The SEM images of the samples are shown in Figure 4 As shown, from Figure 4 It can be seen that the molecular sieve has a cubic morphology, a particle size of 1.5 to 4 μm, and a multi-level pore structure on the particles.
[0105] The pore size distribution of the molecular sieve is 20 nm to 800 nm, and other properties are shown in Table 2.
[0106] Example 4
[0107] Silica sol (40 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) are respectively used as silicon source, aluminum source and phosphorus source, and triethylamine TEA is used as structure directing agent. The silicon source, aluminum source, phosphorus source, triethylamine TEA and auxiliary structure directing agent C8 are added to water and mixed to obtain a mixture, and the molar ratio of the raw materials is Al2O3:H3PO4:auxiliary structure directing agent C8:structure directing agent:SiO2:H2O is 1:2:0.7:3.0:0.25:63.
[0108] The mixture was crystallized at 150°C at 30 rpm for 6 hours, then the temperature was raised to 200°C and crystallized for 48 hours, then the temperature was lowered to 120°C and crystallized for 6 hours.
[0109] After the crystallization is completed, the crystallized product is cooled, centrifuged, washed, dried at 100° C. for 6 hours, and calcined at 550° C. for 6 hours to obtain SAPO-34 molecular sieve.
[0110] The XRD spectra of the samples are shown in Figure 1 ,from Figure 1 It can be seen that diffraction peaks appear at 9.5°, 15.9°, 20.5°, 26° and 31° for 2θ, indicating that the synthesized product is a pure SAPO-34 molecular sieve.
[0111] The SEM images of the samples are shown in Figure 5 As shown, from Figure 5 It can be seen that the molecular sieve has a cubic morphology, a particle size of 3 to 8 μm, and a multi-level pore structure on the particles.
[0112] The pore size distribution of the molecular sieve is 100 nm to 800 nm, and other properties are shown in Table 2.
[0113] Example 5
[0114] Silica sol (40 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) are respectively used as silicon source, aluminum source and phosphorus source, and triethylamine TEA is used as structure directing agent. The silicon source, aluminum source, phosphorus source, triethylamine TEA and auxiliary structure directing agent C4 are added to water and mixed to obtain a mixture, and the molar ratio of the raw materials is Al2O3:H3PO4:auxiliary structure directing agent C4:structure directing agent:SiO2:H2O is 1.0:2.0:0.35:3.2:1.0:72.
[0115] The mixture was crystallized at 150°C at 30 rpm for 6 hours, then the temperature was raised to 200°C and crystallized for 48 hours, then the temperature was lowered to 120°C and crystallized for 6 hours.
[0116] After the crystallization is completed, the crystallized product is cooled, centrifuged, washed, dried at 100° C. for 6 hours, and calcined at 550° C. for 6 hours to obtain SAPO-34 molecular sieve.
[0117] The XRD spectrum of the sample is as follows Figure 6 As shown, from Figure 6 It can be seen that the synthesized molecular sieve has the characteristic diffraction peaks of SAPO-34 molecular sieve, and the diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31° at 2θ.
[0118] The SEM images of the samples are shown in Figure 7 As shown, the molecular sieve has a cubic morphology, a rough particle surface, and a particle size of 0.5 to 4 μm.
[0119] Example 6
[0120] Silica sol (40 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) are respectively used as silicon source, aluminum source and phosphorus source, and triethylamine TEA is used as structure directing agent. The silicon source, aluminum source, phosphorus source, triethylamine TEA and auxiliary structure directing agent C4 are added to water and mixed to obtain a mixture, and the molar ratio of the raw materials is Al2O3:H3PO4:auxiliary structure directing agent C4:structure directing agent:SiO2:H2O is 1.0:2.0:1.2:3.3:0.3:72.
[0121] The mixture was crystallized at 150°C at 30 rpm for 6 hours, then the temperature was raised to 200°C and crystallized for 48 hours, then the temperature was lowered to 120°C and crystallized for 6 hours.
[0122] After the crystallization is completed, the crystallized product is cooled, centrifuged, washed, dried at 100° C. for 6 hours, and calcined at 550° C. for 6 hours to obtain SAPO-34 molecular sieve.
[0123] The XRD spectrum of the sample is as follows Figure 8 As shown, from Figure 8 It can be seen that the synthesized molecular sieve has the characteristic diffraction peaks of SAPO-34 molecular sieve, and the diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31° at 2θ.
[0124] The SEM images of the samples are shown in Fig. 9 As shown, the molecular sieve has a cubic morphology, a particle size of 1 to 4 μm, and a multi-level pore structure on the particles.
[0125] The pore size distribution of the molecular sieve is 20 nm to 150 nm. Other properties are shown in Table 2.
[0126] Example 7
[0127] Silica sol (40 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) are respectively used as silicon source, aluminum source and phosphorus source, and triethylamine TEA is used as structure directing agent. The silicon source, aluminum source, phosphorus source, triethylamine TEA and auxiliary structure directing agent C4 are added to water and mixed to obtain a mixture, and the molar ratio of the raw materials is Al2O3:H3PO4:auxiliary structure directing agent C4:structure directing agent:SiO2:H2O is 1.0:2.0:1.6:3.3:0.3:72.
[0128] The mixture was crystallized at 150°C at 30 rpm for 6 hours, then the temperature was raised to 200°C and crystallized for 48 hours, then the temperature was lowered to 120°C and crystallized for 6 hours.
[0129] After the crystallization is completed, the crystallized product is cooled, centrifuged, washed, dried at 100° C. for 6 hours, and calcined at 550° C. for 6 hours to obtain SAPO-34 molecular sieve.
[0130] The XRD spectrum of the sample is as follows Fig.10 As shown, from Fig.10 It can be seen that the synthesized molecular sieve has the characteristic diffraction peaks of SAPO-34 molecular sieve, and the diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31° at 2θ.
[0131] The SEM images of the samples are shown in Fig.11 As shown, the molecular sieve has a cubic morphology, a particle size of 0.8 to 3.5 μm, and a multi-level pore structure on the particles.
[0132] The pore size distribution of the molecular sieve is 20 nm to 150 nm. Other properties are shown in Table 2.
[0133] Example 8
[0134] Silica sol (40 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) are respectively used as silicon source, aluminum source and phosphorus source, and tetraethylammonium hydroxide is used as structure directing agent. The silicon source, aluminum source, phosphorus source, tetraethylammonium hydroxide and auxiliary structure directing agent C8 are added to water and mixed to obtain a mixture, and the molar ratio of the raw materials is Al2O3:H3PO4:auxiliary structure directing agent C8:structure directing agent:SiO2:H2O is 1.0:2.0:0.75:3.3:0.3:72.
[0135] The mixture was crystallized at 150°C at 30 rpm for 6 hours, then the temperature was raised to 200°C and crystallized for 48 hours, then the temperature was lowered to 120°C and crystallized for 6 hours.
[0136] After the crystallization is completed, the crystallized product is cooled, centrifuged, washed, dried at 100° C. for 6 hours, and calcined at 550° C. for 6 hours to obtain SAPO-34 molecular sieve.
[0137] The XRD spectrum of the sample is as follows Fig.12 As shown, from Fig.12 It can be seen that the synthesized molecular sieve has the characteristic diffraction peaks of SAPO-34 molecular sieve, and the diffraction peaks belonging to SAPO-34 molecular sieve appear at 9.5°, 15.9°, 20.5°, 26° and 31° at 2θ.
[0138] The SEM images of the samples are shown in Fig.13As shown, the molecular sieve has a cubic morphology, a particle size of 0.9 to 3 μm, and a multi-level pore structure on the particles.
[0139] The pore size distribution of the molecular sieve is 20 nm to 100 nm. Other properties are shown in Table 2.
[0140] Comparative Example 1
[0141] Silica sol (40 wt% SiO2), pseudo-boehmite (70 wt% Al2O3) and phosphoric acid (85 wt% H3PO4) are respectively used as silicon source, aluminum source and phosphorus source, and triethylamine TEA is used as structure directing agent. The silicon source, aluminum source, phosphorus source and triethylamine TEA are added into water and mixed to obtain a mixture, and the molar ratio of the raw materials is Al2O3:H3PO4:structure directing agent:SiO2:H2O is 1.0:2.0:3.3:0.3:72.
[0142] The mixture was crystallized at 180°C at 20 rpm for 60 hours, then the temperature was raised to 200°C and crystallized for 20 hours, then the temperature was lowered to 120°C and crystallized for 10 hours.
[0143] After the crystallization is completed, the crystallized product is cooled, centrifuged, washed, dried at 100° C. for 6 hours, and calcined at 550° C. for 6 hours to obtain SAPO-34 molecular sieve.
[0144] The XRD spectrum of the sample is as follows Fig.14 As shown, from Fig.14 It can be seen that the synthesized molecular sieve has characteristic diffraction peaks of SAPO-34 molecular sieve, and diffraction peaks belonging to SAPO-34 appear at 9.5°, 15.9°, 20.5°, 26° and 31° at 2θ.
[0145] The SEM images of the samples are shown in Fig.15 As shown, from Fig.15 It can be seen that the molecular sieve has a cube-like appearance (typical SAPO-34 molecular sieve morphology), and the particle size of SAPO-34 particles is 4-8 μm. There are no multi-level pores on the SAPO-34 cube-like particles.
[0146] Test Case
[0147] The molecular sieves obtained in the above examples and comparative examples were used as catalysts in the methanol to olefins reaction, wherein the application test conditions were: WHSV was 6h -1 , the reaction temperature is 460°C. The specific reaction performance is listed in Table 1.
[0148] Among them, the diene yield is the sum of the ethylene yield and the propylene yield.
[0149] Product conversions and selectivities were calculated on a CH2 basis.
[0150] The life of the catalyst refers to the time when the diene yield reaches the highest point. If the reaction continues, the diene yield will drop rapidly and the by-products will increase rapidly.
[0151] Table 1 Catalytic results of molecular sieves obtained in Examples and Comparative Examples in methanol to olefins
[0152]
[0153] Note: In the present invention, the yield of each product is based on mass.
[0154] Table 2 Properties of the molecular sieve samples obtained in Examples and Comparative Examples
[0155]
[0156] It can be seen from Table 1 that the catalytic effect of the embodiment is significantly better than that of the comparative example 1, which proves that the SAPO-34 synthesized by the present invention can improve the diene yield in the methanol to olefin reaction and has a longer catalyst life.
[0157] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.
Claims
1. A structure-directing composition for preparing a SAPO-34 molecular sieve, comprising a first structure-directing agent and a second structure-directing agent, wherein the first structure-directing agent comprises triethylamine and / or tetraethylammonium hydroxide, and the second structure-directing agent comprises a compound represented by formula I, In formula I, X is selected from halogen, and R is selected from C3-C10 straight or branched alkyl.
2. The structure-directed composition according to claim 1, characterized in that: X is selected from bromine, R is selected from a C4-C8 straight-chain alkyl group, preferably, the second structure directing agent is selected from one or more of triethyl-n-butylammonium bromide, triethyl-n-hexylammonium bromide and triethyl-n-octylammonium bromide; and / or The molar ratio of the second structure directing agent to the first structure directing agent is (0.1-0.5):1, preferably (0.2-0.4):
1.
3. A SAPO-34 molecular sieve, wherein the raw materials for its preparation include an aluminum source, a phosphorus source, a silicon source and the structure-directed composition according to claim 1 or 2, Preferably, the SAPO-34 molecular sieve has a cubic morphology; Preferably, the SAPO-34 molecular sieve has a multi-level pore structure, and the pore size distribution of the multi-level pores is 10nm-1500nm. Preferably, the aluminum source is selected from one or more of pseudo-boehmite, aluminum isopropoxide, alumina, aluminum nitrate, aluminum chloride and aluminum sulfate; 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 silicon source is selected from one or more of silica sol, white carbon black and tetraethyl orthosilicate.
4. A method for preparing SAPO-34 molecular sieve, comprising: S1: providing a mixture including an aluminum source, a phosphorus source, a silicon source, a first structure directing agent, a second structure directing agent and water; S2: crystallizing the mixture in S1; Wherein, the first structure directing agent comprises triethylamine and / or tetraethylammonium hydroxide, and the second structure directing agent comprises a compound represented by formula I, In formula I, X is selected from halogen, and R is selected from C3-C10 straight or branched alkyl.
5. The preparation method according to claim 4, characterized in that: X is selected from bromine, R is selected from a C4-C8 straight chain alkyl group, Preferably, the second structure directing agent is selected from one or more of triethyl-n-butylammonium bromide, triethyl-n-hexylammonium bromide and triethyl-n-octylammonium bromide.
6. The preparation method according to claim 4 or 5, characterized in that: The aluminum source is calculated as Al2O3, and the molar ratio of the second structure directing agent to the aluminum source is (0.3-2.0):1, preferably (0.4-1.5):1, and more preferably (0.6-1.2):1; and / or The molar ratio of the second structure directing agent to the first structure directing agent is (0.1-0.5):1, preferably (0.2-0.4):
1.
7. The preparation method according to any one of claims 4 to 6, characterized in that: The aluminum source is calculated as Al2O3, and the molar ratio of the first structure directing agent to the aluminum source is (1.5-5):1, preferably (2.5-4):1; and / or The aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, and the molar ratio of the silicon source to the aluminum source is (0.1-1.0):1, preferably (0.2-0.5):1; and / or The aluminum source is calculated as Al2O3, the phosphorus source is calculated as H3PO4, and the molar ratio of the phosphorus source to the aluminum source is (1-3):1, preferably (1.5-2.5):1; and / or The aluminum source is calculated as Al2O3, and the molar ratio of the water to the aluminum source is (30-90):1, preferably (40-80):
1.
8. The preparation method according to any one of claims 4 to 7, characterized in that: The aluminum source is selected from one or more of pseudo-boehmite, aluminum isopropoxide, aluminum oxide, aluminum nitrate, aluminum chloride and aluminum sulfate; 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 silicon source is selected from one or more of silica sol, white carbon black and tetraethyl orthosilicate.
9. The preparation method according to any one of claims 4 to 8, characterized in that: The crystallization treatment is carried out under stirring conditions, and preferably the stirring speed is 5 rpm to 50 rpm; Preferably, the crystallization process includes a first crystallization process, a second crystallization process and a third crystallization process performed sequentially. More preferably, the temperature of the first crystallization treatment is 120°C-160°C, and the time of the first crystallization treatment is 3h-12h; the temperature of the second crystallization treatment is 190°C-210°C, and the time of the second crystallization treatment is 20h-60h; the temperature of the third crystallization treatment is 100°C-150°C, and the time of the third crystallization treatment is 5h-20h.
10. Use of the SAPO-34 molecular sieve according to claim 3 or the SAPO-34 molecular sieve prepared by the preparation method according to any one of claims 4 to 9 in a methanol to olefins reaction; Preferably, the reaction conditions of the methanol to olefins reaction are: reaction pressure is normal pressure-1.0 MPa, reaction temperature is 390°C-515°C, methanol feed weight space velocity is 1h -1 -100h -1 .