Nanometer SAPO-34 molecular sieve as well as preparation method and application thereof

Abstract

The invention discloses a nano SAPO-34 molecular sieve and a preparation method and application thereof.The method comprises the steps that an aluminum source, a phosphorus source, a silicon source, modified silane, organic amine, mother liquor and water are mixed and stirred to be uniform, and initial gel is obtained; heating and crystallizing the initial gel, separating, washing and drying to obtain the nano SAPO 34 molecular sieve, the average crystal particle size of the nano SAPO 34 molecular sieve obtained by the method is 100-900 nm, and the nano SAPO 34 molecular sieve has excellent performance when being used for catalyzing the process of preparing olefin or gas adsorption separation from methanol and / or dimethyl ether.

Description

Technical Field

[0001] The present application relates to a nano SAPO-34 molecular sieve and a preparation method and application thereof, belonging to the technical field of molecular sieve catalysts. Background Art

[0002] SAPO-34 is a zeolite with a chabazite (CHA) configuration, first synthesized by Union Carbide in 1984. It features an ellipsoidal cage of eight-membered rings stacked together by double six-membered rings and a three-dimensional intersecting pore structure. Its pore size is 0.38 nm × 0.38 nm, and its cage size is 1.0 nm × 0.67 nm, making it a small-pore molecular sieve. SAPO-34 exhibits exceptional shape selectivity (>80%) for ethylene and propylene in the methanol-to-olefins (MTO) reaction due to its excellent shape-selective properties, moderate acid strength, and good hydrothermal stability. Therefore, SAPO-34 is considered an ideal catalyst for this reaction and is the primary active component of current commercial MTO catalysts.

[0003] The MTO reaction is a typical acid-catalyzed reaction. However, the catalyst is highly susceptible to carbon deposition and deactivation during the MTO process. This is because the microporous structure of the SAPO-34 molecular sieve itself limits its mass transfer efficiency, resulting in low utilization of the active sites of the SAPO-34 molecular sieve catalyst and prone to pore blockage and carbon deposition. Although fluidized bed technology allows for the regeneration of SAPO-34 molecular sieve catalysts and has been applied in commercial MTO processes, regeneration still cannot avoid carbon loss, and the catalyst is subject to wear and tear. To address this issue, attempts have been made to synthesize nano-SAPO-34 molecular sieves, specifically small crystals of nano-SAPO-34 molecular sieves, to reduce mass transfer resistance during the reaction, enhance molecular diffusion during the reaction, and improve the reaction life and selectivity for light olefins.

[0004] However, although there are more than 85 organic templates that can be used to generate SAPO-34 molecular sieves, the synthesis of small-crystal SAPO-34 reported so far mostly relies on the same organic template, tetraethylammonium hydroxide (TEAOH), and the template is used in large quantities, is expensive, and has stringent requirements on the types of raw materials and synthesis conditions. In addition, the prior art also discloses strategies such as solvent-free solid-phase synthesis, steam-assisted method, and gas-phase transport method to achieve the synthesis of nano SAPO-34 molecular sieves. Some prior art also combines physical auxiliary means such as microwaves and ultrasound to achieve the synthesis of nano SAPO-34 molecular sieves. However, these methods are either too complex and expensive in terms of templates; or have many synthetic steps and complicated operations; or the synthetic products are accompanied by the presence of amorphous phases and large micron-sized grains, irregular product morphology, low crystallinity, difficulty in removing the template, and difficulty in centrifugal separation of the product, making them difficult to scale up industrially.

[0005] Furthermore, with increasing environmental pressure on businesses, higher demands are being placed on the green production of SAPO-34 molecular sieve catalysts. Furthermore, with the widespread adoption of MTO technology, annual consumption of MTO catalysts has exceeded 10,000 tons. Traditional SAPO-34 molecular sieve synthesis is achieved via a hydrothermal process, which typically produces a large amount of mother liquor containing unreacted raw materials and organic templates. Discharge of this mother liquor not only wastes raw materials but also causes environmental pollution. Summary of the Invention

[0006] The present application provides a preparation method for synthesizing nano SAPO-34 molecular sieves by recycling mother liquor, and its products and applications, which can realize resource utilization of synthetic mother liquor and obtain nano SAPO-34 molecular sieves with good catalytic performance.

[0007] The first aspect of the present application provides a method for synthesizing nano-SAPO-34 molecular sieves, comprising the following steps:

[0008] a) mixing an aluminum source, a phosphorus source, a silicon source, a modified silane, an organic amine, a mother liquor and water and stirring them uniformly to obtain an initial gel;

[0009] b) heating and crystallizing the initial gel under closed conditions to obtain a crystallized product;

[0010] c) separating, washing, and drying the crystallized product to obtain the nano SAPO-34 molecular sieve.

[0011] Optionally, the modified silane is selected from at least one of octyltrimethoxysilane, nonyltrimethoxysilane, decyltrimethoxysilane, undecyltrimethoxysilane, dodecyltrimethoxysilane, tridecyltrimethoxysilane, tetradecyltrimethoxysilane, pentadecyltrimethoxysilane, hexadecyltrimethoxysilane, heptadecyltrimethoxysilane and octadecyltrimethoxysilane.

[0012] Optionally, the silicon source is selected from at least one of tetraethyl orthosilicate, silica sol, silica gel, white carbon black, activated silica and metakaolin.

[0013] Optionally, the organic amine is selected from at least one of diethylamine, triethylamine, di-n-propylamine, diisopropylamine, n-butylamine, morpholine, cyclohexylamine, piperazine and tetraethylammonium hydroxide.

[0014] Optionally, the aluminum source is selected from at least one of aluminum isopropoxide, pseudo-boehmite, aluminum oxide, aluminum hydroxide and sodium metaaluminate.

[0015] Optionally, the phosphorus source is selected from at least one of orthophosphoric acid, metaphosphoric acid, phosphorous acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, organic phosphides and phosphorus oxides.

[0016] Optionally, the aluminum source is calculated as Al2O3, the phosphorus source is calculated as P2O5, the silicon source and the modified silane are each calculated as SiO2, and the molar ratio of the components in the initial gel is, aluminum source: phosphorus source: silicon source: modified silane: organic amine: water = 1.0: 0.5~2.0: 0.05~1.2: 0.01~0.5: 1.0~6.0: 20~200; preferably, aluminum source: phosphorus source: silicon source: modified silane: organic amine: water = 1.0: 0.8~1.5: 0.1~1.0: 0.01~0.3: 2.0~4.0: 30~100.

[0017] Optionally, the ratio of the mass of the silicon-phosphorus-aluminum oxides contained in the mother solution to the total mass of the silicon-phosphorus-aluminum oxides contained in the initial gel is 1% to 60%.

[0018] The second aspect of the present application provides a nano SAPO-34 molecular sieve prepared according to the method of the first aspect of the present application, wherein the average crystal size of the nano SAPO-34 molecular sieve is 100 nm to 900 nm.

[0019] The third aspect of the present application provides the use of the nano SAPO-34 molecular sieve provided in the second aspect of the present application in the reaction of producing olefins from methanol and / or dimethyl ether.

[0020] The fourth aspect of the present application provides the use of the nano SAPO-34 molecular sieve provided in the second aspect of the present application in a gas adsorption separation process.

[0021] The beneficial effects of this application include:

[0022] (1) The present application adopts the synergistic effect of modified silane and recycled mother liquor to synthesize nano SAPO-34 molecular sieves. The process is simple and has good repeatability, which is conducive to large-scale industrial production; at the same time, it reduces pollution and lowers production costs.

[0023] (2) By using the method of the present application, the average crystal particle size of the product nano SAPO-34 molecular sieve can be adjusted within a certain range by adjusting the molar ratio of the silicon source and the modified silane.

[0024] (3) The synthesis method of the present application has a fast crystallization speed and a short crystallization time, which can save energy and further reduce production costs.

[0025] (4) The nano SAPO-34 molecular sieve prepared in this application has high crystallinity, high purity and high yield, and the average crystal particle size of the nano SAPO-34 molecular sieve can be adjusted between 100 nm and 900 nm.

[0026] (5) The nano SAPO-34 molecular sieve prepared in this application is used in the reaction of methanol and / or dimethyl ether to olefins and has a good catalytic effect.

[0027] (6) The nano SAPO-34 molecular sieve prepared in this application can be used in gas adsorption separation processes and has good regeneration performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the X-ray powder diffraction pattern of the nano SAPO-34 molecular sieve prepared in Example 1.

[0029] Figure 2 This is a SEM photograph of the nano SAPO-34 molecular sieve prepared in Example 1, with a scale of 1 μm. DETAILED DESCRIPTION

[0030] The first aspect of the present application provides a method for synthesizing nano-SAPO-34 molecular sieves, comprising the following steps:

[0031] a) mixing an aluminum source, a phosphorus source, a silicon source, a modified silane, an organic amine, a mother liquor and water and stirring them uniformly to obtain an initial gel;

[0032] b) heating and crystallizing the initial gel under closed conditions to obtain a crystallized product;

[0033] c) separating, washing, and drying the crystallized product to obtain the nano SAPO-34 molecular sieve.

[0034] In the present application, the mother liquor refers to the mother liquor generated after the crystallization of SAPO-34 molecular sieve is completed. The mother liquor may be diluted with water or concentrated, and may also contain the washing liquid of the molecular sieve, which does not affect the use effect.

[0035] In some embodiments, the modified silane is selected from at least one of octyltrimethoxysilane, nonyltrimethoxysilane, decyltrimethoxysilane, undecyltrimethoxysilane, dodecyltrimethoxysilane, tridecyltrimethoxysilane, tetradecyltrimethoxysilane, pentadecyltrimethoxysilane, hexadecyltrimethoxysilane, heptadecyltrimethoxysilane, and octadecyltrimethoxysilane.

[0036] In some embodiments, the silicon source is selected from at least one of tetraethyl orthosilicate, silica sol, silica gel, white carbon black, activated silica, and metakaolin.

[0037] In some embodiments, the organic amine is used as a template agent, which is selected from at least one of diethylamine (DEA), triethylamine (TEA), di-n-propylamine (DPA), diisopropylamine (DiPA), n-butylamine (BA), morpholine (MOR), cyclohexylamine (CA), piperazine (PIP) and tetraethylammonium hydroxide (TEAOH).

[0038] In some embodiments, the aluminum source is selected from at least one of aluminum isopropoxide, pseudo-boehmite, alumina, aluminum hydroxide, and sodium metaaluminate.

[0039] In some embodiments, the phosphorus source is selected from at least one of orthophosphoric acid, metaphosphoric acid, phosphorous acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, organic phosphorus compounds, and phosphorus oxides.

[0040] In some embodiments, the aluminum source is calculated as Al2O3, the phosphorus source is calculated as P2O5, the silicon source and the modified silane are each calculated as SiO2, and the molar ratio of the components in the initial gel is, aluminum source: phosphorus source: silicon source: modified silane: organic amine: water = 1.0: 0.5~2.0: 0.05~1.2: 0.01~0.5: 1.0~6.0: 20~200.

[0041] In some embodiments, in the initial gel, the molar ratio of Al2O3 to P2O5 can be independently selected from any value among 1:0.5, 1:0.7, 1:1.0, 1:1.2, 1:1.5, 1:1.7, 1:2.0, or any range therebetween.

[0042] In some embodiments, in the initial gel, the molar ratio of Al2O3 to SiO2 can be independently selected from any value among 1:0.05, 1:0.07, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.5, 1:0.7, 1:1.0, 1:1.2, or any range between two values.

[0043] In some embodiments, in the initial gel, the molar ratio of Al2O3 to modified silane can be independently selected from any value among 1:0.01, 1:0.03, 1:0.07, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.5, or any range therebetween.

[0044] In some embodiments, in the initial gel, the molar ratio of Al2O3 to the organic amine can be independently selected from any value among 1:1.0, 1:1.5, 1:2.0, 1:2.5, 1:3.0, 1:3.5, 1:4.0, 1:4.5, 1:5.0, 1:5.5, 1:6.0, or any range between two values.

[0045] In some embodiments, in the initial gel, the molar ratio of Al2O3 to H2O can be independently selected from any value among 1:20, 1:40, 1:50, 1:80, 1:100, 1:120, 1:140, 1:150, 1:180, 1:200, or any range therebetween.

[0046] In some preferred embodiments, the molar ratio of the components in the initial gel is: aluminum source: phosphorus source: silicon source: modified silane: organic amine: water = 1.0: 0.8-1.5: 0.1-1.0: 0.01-0.3: 2.0-4.0: 30-100.

[0047] In some preferred embodiments, the ratio of the mass of the silicon-phosphorus-aluminum oxides contained in the mother solution to the total mass of the silicon-phosphorus-aluminum oxides contained in the initial gel is 1% to 60%.

[0048] In some embodiments, the water is deionized water.

[0049] It should be noted that, in the present application, the mother liquor also contains water. The water in the initial gel of the present application includes the water in the mother liquor and the added water. The water in the molar ratio of each component in the initial gel refers to the final water content.

[0050] In some embodiments, in step a), the aluminum source, phosphorus source, silicon source, modified silane, organic amine, mother liquor, and optionally, water are mixed and stirred at room temperature for 12 to 24 hours to obtain a uniform gel.

[0051] In some embodiments, the content of water and silicon-aluminum-phosphorus oxide in the mother liquor can be calculated first, and then the addition amount of aluminum source, phosphorus source, silicon source, organic amine template, modified silane and water can be calculated based on the components of the mother liquor, so that the molar ratio of each component in the initial gel is in line with the scope of this application.

[0052] In some embodiments, in step b), the heating crystallization process comprises: heating to 180-250° C. at a rate of 1-10° C. / min, and hydrothermal crystallization under autogenous pressure for 0.5-90 h.

[0053] In some embodiments, the heating crystallization temperature can be independently selected from any value of 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, or any range therebetween.

[0054] In some embodiments, the crystallization time can be independently selected from any value among 0.5, 1, 2, 3, 5, 8, 12, 24, 36, 48, 60, 90 hours, or any range therebetween.

[0055] In some embodiments, the heating crystallization process may include two stages:

[0056] The first stage: the temperature is raised to 120-170°C at a rate of 1-10°C / min, and hydrothermal crystallization is carried out under autogenous pressure for 3-24 hours;

[0057] The second stage: raise the temperature to 180-250°C at a rate of 1-10°C / min, and hydrothermally crystallize under autogenous pressure for 0.5-60h.

[0058] In some embodiments, the heating rates of the first stage and the second stage can be independently selected from any value of 1, 3, 5, 8, 10° C. / min or any range therebetween.

[0059] The inventors found that the modified silane and mother liquor in the initial gel can work synergistically to achieve an average crystal particle size of 100nm to 900nm under different reaction materials and crystallization conditions, and the method has universal applicability.

[0060] In this application, the "sealed conditions" are well known in the field of molecular sieve preparation, usually a pressure vessel. Those skilled in the art may also select other sealing conditions according to specific needs, and this application does not limit them here.

[0061] In some embodiments, in step b), the heating crystallization can be performed in a high-pressure synthesis reactor.

[0062] In some embodiments, in step c), after the crystallization is completed, the crystallized product can be rapidly cooled to room temperature in a synthesis reactor, solid-liquid separation can be performed, washed with deionized water, and dried to obtain nano SAPO-34 molecular sieve.

[0063] In the present application, the separation, washing and drying of the crystallized product are conventional technical means in the art and are not limited in the present application.

[0064] The second aspect of the present application provides a nano SAPO-34 molecular sieve prepared according to the method of the first aspect of the present application, wherein the average crystal size of the nano SAPO-34 molecular sieve is 100 nm to 900 nm.

[0065] In the present application, the average crystal size can be adjusted within the above range by adjusting the molar ratio of the silicon source and the modified silane in the initial gel during the preparation process, combined with the crystallization temperature and crystallization time.

[0066] In some embodiments, the average particle size of the nano SAPO-34 molecular sieve crystals can be independently selected from any value of 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, or any range between the two.

[0067] The nano SAPO-34 molecular sieve prepared by the above method of the present application can be used as a catalyst for the reaction of methanol and / or dimethyl ether to olefins and the dehydration reaction of alcohols after high-temperature calcination, and can also be used as a gas adsorbent.

[0068] SAPO-34 molecular sieve is calcined at high temperature to remove residual organic matter in the product, such as organic amine template agents, etc. This is a common technical means in this field. Those skilled in the art can select the calcination conditions according to the specific situation, and this application does not limit it here.

[0069] The third aspect of the present application provides the use of the nano SAPO-34 molecular sieve provided in the second aspect of the present application in the reaction of producing olefins from methanol and / or dimethyl ether.

[0070] The fourth aspect of the present application provides the use of the nano SAPO-34 molecular sieve provided in the second aspect of the present application in a gas adsorption separation process.

[0071] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0072] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0073] The analysis method in the examples of this application is as follows:

[0074] X-ray powder diffraction (XRD) phase analysis was performed using an X'PertPRO X-ray diffractometer from PANalytical, the Netherlands, using a Cu target, a Kα radiation source (λ=0.15418 nm), a voltage of 40 kV, and a current of 40 mA.

[0075] X-ray fluorescence spectrometry (XRF) elemental composition analysis was performed using a Magic-601 analyzer from Philips, the Netherlands. Measurement conditions: voltage 40 kV, current 40 mA; samples were pelletized before testing.

[0076] The micromorphology of the samples was observed using a Hitachi SU8020 scanning electron microscope (SEM) with an accelerating voltage of 2.0 kV. The samples were not subjected to gold spraying after calcination.

[0077] The average crystal particle size of the sample was measured using a Zetasizer Nano laser scattering particle size distribution analyzer from Malvern Company to measure the crystal median diameter (D50) of the SAPO-34 molecular sieve, and ethanol was used as the dispersant.

[0078] Preparation Example 1 Preparation of mother liquor

[0079] The mother liquor can be any industrial mother liquor produced by any company using any recipe to produce SAPO-34 molecular sieves, or it can be a mother liquor obtained by diluting or concentrating such a mother liquor; or it can be a diluted or concentrated SAPO-34 molecular sieve washing liquid. This example describes a mother liquor produced independently to illustrate this invention and does not limit this application in any way.

[0080] Refer to Sample 1 in Table 1 #The initial gel ratio was set at 1.0 Al2O3:1.0 P2O5:0.3 SiO2:2.0 DEA:50 H2O. The process was as follows: 618.8 g of 70% pseudo-boehmite was added to 3256.9 g of deionized water, stirred evenly, and then 980.0 g of 85% H3PO4 solution was added. Stirring continued for 12 hours. 268.6 g of 98% ethyl orthosilicate was then added to the synthesized sol. 628.2 g of 99% DEA was added while stirring, and stirring continued until a uniform gel formed. This was the initial gel. The gel was then placed in a sealed stainless steel reactor and heated to 200°C at a rate of 1°C / min for 24 hours for crystallization. After crystallization, the material was directly treated with organic amine evaporation. The resulting solid product was centrifuged, washed with deionized water until neutral, and dried in air at 120°C for 24 hours. XRD analysis confirmed the product as SAPO-34 molecular sieve. The supernatant obtained from the centrifugation was the crystallization mother liquor (designated MY1). MY1 was concentrated to obtain a concentrated mother liquor (designated MY2). The dry matter content of MY1 and MY2 was determined, and the silicon, phosphorus, and aluminum oxide content was determined using XRF. The results are shown in Table 2.

[0081] Example 1 Sample 1 # Preparation

[0082] According to sample 1 in Table 1 # The initial gel ratio was 1.0Al2O3:1.0P2O5:0.3SiO2:0.2MSA:2.0DEA:50H2O. 40g of mother liquor MY1 was used, and the amounts of aluminum, silicon, and phosphorus sources required were calculated based on the ratio. The mass ratio of silicon, phosphorus, and aluminum oxides contained in the added 40g mother liquor to the mass of silicon, phosphorus, and aluminum oxides contained in the synthesized gel was 24.2%. Specifically, first, 5.54g of 98% pseudo-boehmite was added to 40g of mother liquor MY1, stirred evenly, and then 8.51g of 85% H3PO4 solution was added thereto, and stirring was continued for 12 hours; then 2.84g of 98% ethyl orthosilicate was added to the synthetic sol, and 7.39g of 99% DEA and 2.38g of 98.5% octyltrimethoxysilane (MSA) were added under stirring, and then 3.27g of deionized water was added and stirring was continued until a uniform gel was formed, which was the initial gel. The gel was placed in a stainless steel reactor with a polytetrafluoroethylene lining and sealed, and heated to 250°C at a heating rate of 2°C / min for crystallization for 0.5h. The obtained solid product was centrifuged, washed with deionized water until neutral, and dried in air at 120°C for 24h to obtain 1# Sample. XRD analysis showed 1 # The XRD patterns of the samples showed a classic CHA structure, such as Figure 1 As shown; This shows that 1 # The sample is SAPO-34 molecular sieve. The characterization results of nano laser scattering particle size distribution analyzer show that 1 # The crystal median diameter (D50) of the sample is 200nm. # The sample is nano SAPO-34 molecular sieve. Figure 2 The synthesized nano SAPO-34 molecular sieve (sample 1 # ) Typical morphology. Sample 1 # The types of raw materials, molar ratio, crystallization temperature, crystallization time and average crystal particle size of the product in the initial gel are shown in Table 1.

[0083] Example 2 Sample 2 # Preparation

[0084] According to sample 2 in Table 1 # The initial gel ratio was 1.0Al2O3:0.9P2O5:0.20SiO2:0.10MSB:3.0TEA:60H2O. 30g of mother liquor MY2 was used, and the amounts of aluminum, silicon, and phosphorus sources required were calculated based on the ratio. The mass ratio of silicon, phosphorus, and aluminum oxides in the added 30g mother liquor to the mass of silicon, phosphorus, and aluminum oxides in the synthesized gel was 39.6%. Specifically, first add 25.22g of deionized water and 4.61g of aluminum hydroxide with a mass fraction of 70% to 30.0g of mother liquor MY2, stir evenly, then add 5.86g of H3PO4 solution with a mass fraction of 85%, and continue stirring for 24 hours; then add 1.63g of silica sol with a mass fraction of 30% to the synthetic sol, and continue to add 11.08g of TEA with a mass fraction of 99% and 1.28g of nonyltrimethoxysilane (MSB) with a mass fraction of 97% under stirring, and continue stirring until a uniform gel is formed, which is the initial gel. The gel is placed in a stainless steel reactor with a polytetrafluoroethylene lining and sealed, heated to 240°C at a heating rate of 3°C / min and crystallized for 1h. The obtained solid product is centrifuged, washed with deionized water until neutral, and dried in air at 120°C for 24h to obtain 2 # Sample. XRD analysis showed 2 # The XRD peak positions of the samples and Figure 1 The XRD is consistent; this shows that 2 # The sample is SAPO-34 molecular sieve. The characterization results of nano laser scattering particle size distribution analyzer show that 2 # The crystal median diameter (D50) of the sample is 200nm. #The sample is nano SAPO-34 molecular sieve. Sample 2 # The types of raw materials, molar ratio, crystallization temperature, crystallization time and average crystal particle size of the product in the initial gel are shown in Table 1.

[0085] Example 3-Example 9 Sample 3 # -9 # Preparation

[0086] Sample 3 # -9 # Nano SAPO-34 molecular sieves are also synthesized using an organic amine template and modified silane synergistic system: Sample 3 # -9 # The specific glue preparation process refers to sample 2 in Example 3. # The batching process; Order No. Sample 3 # , 5 # , 7 # , 9 # Use mother liquor MY1 for batching, even number sample 4 # , 6 # , 8 # The mother liquor MY2 is used for batching; the amount of aluminum source, silicon source, and phosphorus source to be added is calculated based on the gel ratio of each ingredient; the mass ratio of silicon, phosphorus, and aluminum oxides contained in the added mother liquor to the mass ratio of silicon, phosphorus, and aluminum oxides contained in the synthetic gel is 15%. Sample 3 # -9 # The crystallization was carried out by heating at a rate of 1°C / min. XRD analysis showed that the synthesized 3 # -9 # The XRD peak positions of the samples and Figure 1 The XRD is consistent; this shows that 3 # -9 # The sample is SAPO-34 molecular sieve. The characterization results of nano laser scattering particle size distribution analyzer show that 3 # -9 # The average crystal size of the sample is between 100 and 500 nm. # -9 # All samples are nano SAPO-34 molecular sieve. Sample 3 # -9 # The raw material types, molar ratios, crystallization temperatures, crystallization times and average crystal particle sizes of the products are shown in Table 1.

[0087] Example 10-Example 18 Sample 10 # -18 # Preparation

[0088] Sample 10 # -18 #The nano SAPO-34 molecular sieve is also synthesized using an organic amine template and a modified silane synergistic system: Sample 10 # -18 # The specific preparation process can be synthesized according to the example 1 # -9 # ; Sample No. 11 # , 13 # , 15 # 、17 # Use mother liquor MY1 for batching, even number sample 10 # , 12 # 、14 # , 16 # , 18 # The mother liquor MY2 is used for batching; the amount of aluminum source, silicon source and phosphorus source to be added is calculated based on the gel ratio of each ingredient; the mass ratio of silicon, phosphorus and aluminum oxides contained in the added mother liquor to the mass ratio of silicon, phosphorus and aluminum oxides contained in the synthetic gel is 10%. Sample 10 # -18 # The crystallization was carried out by a two-stage heating method (heating rate of 4℃ / min). XRD analysis showed that the synthesized 10 # -18 # The XRD peak positions of the samples and Figure 1 The XRD is consistent; this shows that 10 # -18 # The sample is SAPO-34 molecular sieve. The characterization results of nano laser scattering particle size distribution analyzer show that 10 # -18 # The average crystal size of the sample is between 200 and 900 nm. # -18 # All samples are nano SAPO-34 molecular sieve. Sample 10 # -18 # The specific raw material types, molar ratios, crystallization temperatures, crystallization times and average crystal particle sizes of the products are shown in Table 1.

[0089] Example 19-Example 24 Sample 19 # -twenty four # Preparation

[0090] Sample 19 # -twenty four # Nano-SAPO-34 molecular sieves were also synthesized using a dual organic amine template and modified silane synergistic system: Sample 19 # -twenty four # The specific preparation process can be synthesized according to the example 1 # -18 # Any sample batching order is carried out, sample 19# -twenty one # The mother liquor MY1 was used for batching and crystallization was carried out in a one-stage heating method (heating rate was 2°C / min); Sample 22 # -twenty four # The mother liquor MY2 was used for batching and crystallization was carried out in a two-stage heating process (heating rate of 1°C / min). The amount of aluminum source, silicon source, and phosphorus source required was calculated based on the gel ratio of each ingredient; the mass ratio of silicon, phosphorus, and aluminum oxides contained in the added mother liquor to the mass ratio of silicon, phosphorus, and aluminum oxides contained in the synthesis gel was 6%. XRD analysis showed that the synthesized 19 # -twenty four # The XRD peak positions of the samples and Figure 1 The XRD results are consistent; this indicates that 19 # -twenty four # The sample is SAPO-34 molecular sieve. The characterization results of nano laser scattering particle size distribution analyzer show that 19 # -twenty four # The average crystal size of the sample is between 100 and 300 nm. # -twenty four # All samples are nano SAPO-34 molecular sieve. Sample 19 # -twenty four # The specific raw material types, molar ratios, crystallization temperatures, crystallization times and average crystal particle sizes of the products are shown in Table 1.

[0091] Comparative Example 1 Comparative Sample S1

[0092] According to sample 2 in Table 1 # The initial gel ratio is 1.0Al2O3:0.9P2O5:0.20SiO2:0.10MSB:3.0TEA:60H2O. The specific batching process is the same as that of Example 2, except that no mother liquor is added in the preparation step of the synthetic gel, but is completely replaced by deionized water and silicon, phosphorus and aluminum raw materials; other specific raw material types, crystallization temperature and crystallization time are exactly the same as those of Sample 2. # The resulting sample was designated as comparative sample S1. XRD analysis showed that the SAPO-34 molecular sieve peak was completely absent from the XRD peak position of sample S1, indicating that the synthesized sample S1 was an uncrystallized amorphous phase. Nanolaser scattering particle size distribution analyzer characterization results showed that the average crystal size of sample S1 was 35 nm; this result is consistent with the XRD characterization results, indicating that S1 was an uncrystallized amorphous phase. The synthetic raw material types, molar ratios, crystallization temperature, crystallization time, and average crystal size of the product of comparative sample S1 are shown in Table 1.

[0093] Comparative Example 2 Preparation of Comparative Sample S2

[0094] According to sample 2 in Table 1# The initial gel ratio is 1.0Al2O3:0.9P2O5:0.20SiO2:3.0TEA:60H2O. The specific batching process is the same as that of sample 2 in Example 2. # The difference is that nonanyltrimethoxysilane (MSB) is not added in the preparation step of the synthetic gel; the obtained sample is recorded as comparative sample S2. XRD analysis shows that the XRD peak position of sample S2 is Figure 1 The XRD patterns are consistent, indicating that sample S2 is SAPO-34 molecular sieve. Nanolaser scattering particle size distribution analysis results show that the average crystal size of sample S2 is 1.5 μm. This indicates that sample S2 is a micron-sized SAPO-34 molecular sieve. Table 1 shows the raw material types, molar ratios, crystallization temperature, crystallization time, and average crystal size of the product for comparative sample S2.

[0095] Comparative Example 3 Comparative Sample S3

[0096] Refer to Sample 1 in Table 1 # The initial gel ratio is 1.0Al2O3:0.9P2O5:0.20SiO2:3.0TEA:60H2O for preparation. The specific preparation process is the same as that in Example 1, with two differences: first, the mother liquor is not added in the preparation step of the synthetic gel, but is replaced by ionized water and silicon-phosphorus-aluminum raw materials; second, nonyltrimethoxysilane (MSB) is not added in the preparation step of the synthetic gel; other specific raw material types are exactly the same as in Example 2. The obtained synthetic gel is heated to 200°C at a heating rate of 1°C / min and crystallized for 24h. The crystallized product is centrifuged, washed and dried to obtain comparative sample S3. XRD analysis shows that the XRD peak position of sample S3 and Figure 1 The XRD patterns are consistent, indicating that sample S3 is SAPO-34 molecular sieve. Nanolaser scattering particle size distribution analysis results show that the average crystal size of sample S3 is 20 μm. This indicates that sample S3 is a micron-sized SAPO-34 molecular sieve. Table 1 shows the raw material types, molar ratios, crystallization temperature, crystallization time, and average crystal size of the product for comparative sample S3.

[0097] Table 1 Example 1 # -twenty four # Molecular sieve synthesis ingredients and crystallization conditions

[0098]

[0099]

[0100] Note: Aluminum source: a. Pseudo-boehmite; b. Aluminum hydroxide; c. Aluminum oxide; d. Sodium metaaluminate; e. Aluminum isopropoxide.

[0101] Note: Phosphorus sources: f orthophosphoric acid, g metaphosphoric acid, h phosphorous acid, i ammonium hydrogen phosphate, j ammonium dihydrogen phosphate.

[0102] Note: Silicon source: k tetraethyl orthosilicate; l silica sol; m white carbon black; n silica gel; o activated silica; p metakaolin.

[0103] Note: Modified silane: octyltrimethoxysilane (MSA), nonyltrimethoxysilane (MSB), decyltrimethoxysilane (MSC), undecyltrimethoxysilane (MSD), dodecyltrimethoxysilane (MSE), tridecyltrimethoxysilane (MSF), tetradecyltrimethoxysilane (MSG), pentadecyltrimethoxysilane (MSH), hexadecyltrimethoxysilane (MSI), heptadecyltrimethoxysilane (MSJ), octadecyltrimethoxysilane (MSK).

[0104] Note: Organic amines: diethylamine (DEA), triethylamine (TEA), di-n-propylamine (DPA), diisopropylamine (DiPA), n-butylamine (BA), morpholine (MOR), cyclohexylamine (CA), piperazine (PIP), tetraethylammonium hydroxide (TEAOH).

[0105] Note Φ : The mother liquor used in the synthesis.

[0106] Note & : D50 is the median diameter of the crystallized product obtained by nano-laser particle size analyzer.

[0107] Comparison of the crystallization results of Example 2 with Comparative Examples 1, 2, and 3 in Table 1 shows that the addition of mother liquor to the synthesis system can reduce the average particle diameter of the target product to a certain extent; the addition of modified silane to the synthesis system can also reduce the average particle diameter of the target product to a certain extent. However, only when both the mother liquor and modified silane are added to the synthesis system, their synergistic effect can produce the nanoscale target product.

[0108] Table 2 Dry basis content in mother liquor and content of silicon, phosphorus and aluminum components therein (in terms of oxides, mass %)

[0109]

[0110] Test Example 1 Methanol to Olefins Reaction Performance Test of Samples

[0111] Select Example Sample 2 # 、11 # and 15 #The performance of methanol to olefins reaction was studied. The experimental steps are as follows: the sample was calcined at 600 ° C for 4 hours with air, and then tableted and crushed into 40-60 mesh. 1.0g of sample was weighed and loaded into a fixed bed reactor for evaluation of methanol conversion to olefins reaction. Nitrogen was activated at 550 ° C for 1 hour, and then the temperature was lowered to 470 ° C for reaction. Methanol was carried by nitrogen with a nitrogen flow rate of 40ml / min and a methanol weight space velocity of 2.0h 1 The reaction products were analyzed by online gas chromatography (Varian 3800, FID detector, capillary column PoraPLOT Q-HT). The results of the methanol to olefins reaction are shown in Table 3.

[0112] Table 3 Methanol conversion to olefins reaction results of samples

[0113]

[0114] ※ : Highest (ethylene + propylene) selectivity at 100% methanol conversion

[0115] Test Example 2 Adsorption performance test of samples

[0116] Select Example Sample 7 # Used as a propylene adsorbent. The adsorption isotherm of the sample was measured on an ASAP2020 instrument from Micromeritics, USA. The adsorbed gases were propylene (99.99%) and propane (99.99%). In order to avoid the influence of physically adsorbed water in the molecular sieve on the adsorption test, the sample was calcined at 600°C for 4 hours before the adsorption test and then further treated in the ASAP2020. The treatment conditions were: in an extremely low vacuum (5×10 -3 mmHg), the temperature was raised to 350℃ at a rate of 1℃ / min and maintained for 8 hours. The gas adsorption temperature was controlled by a constant temperature water bath (accuracy: ±0.05℃) and the adsorption temperature was 298K. The results showed that sample 7 # The adsorption capacities for propylene and propane were 2.05 and 1.02 mmol / g, respectively (at a pressure of 101 kPa). The adsorption selectivity calculated at this point was propylene / propane = 2.01.

[0117] After the adsorption experiment, 7 # After the sample was vacuum treated on the ASAP2020 device at room temperature for 30 minutes, the adsorption isotherm was measured again. # The adsorption capacities of the samples for propylene were 2.11 and 1.05 mmol / g, respectively (at a pressure of 101 kPa), indicating that the samples have good regeneration properties and can be regenerated under mild conditions.

[0118] The nano SAPO-34 molecular sieve prepared by the above-mentioned method of the present application has the advantages of high purity, high crystallinity and high yield, has a regular cubic morphology, and the crystal grain size can be adjusted within a certain range; the preparation process of the present application is relatively simple, easy to operate, and has good repeatability, which is more conducive to large-scale industrial production.

[0119] The nano SAPO-34 molecular sieve prepared by the above method of the present application can be used as a catalyst for the methanol to olefin reaction after high-temperature calcination, and can also be used as a propylene adsorbent.

[0120] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for synthesizing nano SAPO-34 molecular sieve, characterized in that: The following steps are involved: a) mixing an aluminum source, a phosphorus source, a silicon source, a modified silane, an organic amine, a mother liquor and water and stirring them uniformly to obtain an initial gel; b) heating and crystallizing the initial gel under closed conditions to obtain a crystallized product; c) separating, washing, and drying the crystallized product to obtain the nano SAPO-34 molecular sieve.

2. The method according to claim 1, characterized in that The modified silane is at least one selected from octyltrimethoxysilane, nonyltrimethoxysilane, decyltrimethoxysilane, undecyltrimethoxysilane, dodecyltrimethoxysilane, tridecyltrimethoxysilane, tetradecyltrimethoxysilane, pentadecyltrimethoxysilane, hexadecyltrimethoxysilane, heptadecyltrimethoxysilane, and octadecyltrimethoxysilane; Preferably, the silicon source is selected from at least one of tetraethyl orthosilicate, silica sol, silica gel, white carbon black, activated silica and metakaolin.

3. The method according to claim 1, characterized in that The organic amine is at least one selected from diethylamine, triethylamine, di-n-propylamine, diisopropylamine, n-butylamine, morpholine, cyclohexylamine, piperazine and tetraethylammonium hydroxide.

4. The method according to claim 1, wherein The aluminum source is selected from at least one of aluminum isopropoxide, pseudo-boehmite, aluminum oxide, aluminum hydroxide and sodium metaaluminate.

5. The method according to claim 1, wherein The phosphorus source is selected from at least one of orthophosphoric acid, metaphosphoric acid, phosphorous acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, organic phosphides and phosphorus oxides.

6. The method according to any one of claims 1 to 5, characterized in that The aluminum source is calculated as Al2O3, the phosphorus source is calculated as P2O5, the silicon source and the modified silane are each calculated as SiO2, and the molar ratio of each component in the initial gel is: aluminum source: phosphorus source: silicon source: modified silane: Organic amine: water = 1.0: 0.5-2.0: 0.05-1.2: 0.01-0.5: 1.0-6.0: 20-200; preferably, aluminum source: phosphorus source: silicon source: modified silane: Organic amine: water = 1.0: 0.8~1.5: 0.1~1.0: 0.01~0.3: 2.0~4.0: 30~100.

7. The method according to any one of claims 1 to 5, characterized in that The ratio of the mass of the silicon-phosphorus-aluminum oxides contained in the mother solution to the total mass of the silicon-phosphorus-aluminum oxides contained in the initial gel is 1% to 60%.

8. The nano SAPO-34 molecular sieve prepared by the method according to any one of claims 1 to 7, characterized in that: The average crystal particle size of the nano SAPO-34 molecular sieve is 100 nm to 900 nm.

9. Use of the nano SAPO-34 molecular sieve prepared by the method according to any one of claims 1 to 7 or the nano SAPO-34 molecular sieve according to claim 8 in the reaction of methanol and / or dimethyl ether to olefins.

10. Use of the nano SAPO-34 molecular sieve prepared by the method according to any one of claims 1 to 7 or the nano SAPO-34 molecular sieve according to claim 8 in a gas adsorption separation process.

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