Method for preparing SAPO co-crystalline molecular sieves using methanol to olefins catalysts

Abstract

The application discloses a method for preparing SAPO eutectic molecular sieves, such as SAPO-18 / SAPO-34 eutectic molecular sieves, by using a methanol-to-olefin (MTO) catalyst. The method uses the MTO catalyst as part of a silicon-aluminum-phosphorus source in a synthesis raw material, and then mixes the MTO catalyst with a silicon source, an aluminum source, a phosphorus source, an organic amine R and deionized water and the like, hydrothermally crystallizes, centrifugally washes and dries to obtain the SAPO eutectic molecular sieves. The method for preparing the SAPO eutectic molecular sieves by using the MTO catalyst solves the problem of large emission of MTO waste catalysts, and also realizes efficient and rapid utilization of the waste catalysts. The SAPO eutectic molecular sieves synthesized by the application are expected to be applied in MTO reactions, removal of nitrogen oxides (NO x ) in motor vehicle exhaust, catalytic methane-to-methanol, gas adsorption separation and the like.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology. Specifically, this invention relates to a method for preparing SAPO eutectic molecular sieves using methanol-to-olefins (MTO) catalysts, such as a method for preparing SAPO-18 / SAPO-34 eutectic molecular sieves.

[0002] This invention also relates to the application of the SAPO eutectic molecular sieve prepared above in the methanol-to-olefins (MTO) reaction or in the treatment of nitrogen oxides (NOx) in motor vehicle exhaust. x Applications in industrial processes such as removal of slag, catalytic production of methanol from methane, and gas adsorption separation. Background Technology

[0003] Energy and the environment are two major themes in today's society. Given my country's resource endowment of "lacking oil and gas but rich in coal", the coal-based route for synthesizing low-carbon olefins (ethylene and propylene), namely the technology for synthesizing low-carbon olefins (MTO) from methanol or dimethyl ether, has been a strategic priority for development in my country.

[0004] MTO technology was commercialized as early as 2010. Currently, the main component of the commercial catalyst for this technology is SAPO-34 molecular sieve. CHA-type SAPO-34 exhibits an ellipsoidal three-dimensional cage-like pore structure with eight-membered ring pores; the diameter of the CHA cage is 0.94 nm, and its pore diameter is only 0.38 nm; therefore, SAPO-34 is highly susceptible to deactivation due to coking. Under high reaction temperatures and high space velocities, the single-pass catalyst lifetime is short. In addition, because MTO industrial plants use fluidized bed reactors, the MTO catalyst continuously circulates and regenerates between the reactor and the regenerator under the action of airflow. Catalyst particles in industrial fluidized bed plants undergo continuous and complex mechanical, thermal, and chemical actions, leading to catalyst wear and breakage. After multiple regenerations, these worn and broken catalysts become fine catalyst powder with significantly reduced catalytic activity. When the activity drops to an unacceptable level, it becomes waste catalyst and cannot be reused in MTO industrial fluidized bed plants.

[0005] The carbon deposits in spent MTO industrial catalysts are mostly polycyclic aromatic hydrocarbons (PAHs). Simple landfill disposal will pollute soil and surface water resources, and the catalysts are expensive, so simple disposal will also result in economic losses. Therefore, recycling the aforementioned SAPO series spent catalysts can reduce environmental pollution and lower the cost of methanol-to-olefins (MTO), which is of great significance for the development of my country's coal chemical industry.

[0006] There are currently few reported methods for the resource utilization of industrial MTO waste catalysts.

[0007] Patent CN101157051A reports a method of using waste catalyst to be recycled as a binder, mixing it with raw materials for preparing fresh microsphere catalysts in a certain proportion, and then spray-drying and calcining it at high temperature after slurry grinding to obtain new microsphere catalysts.

[0008] Patent CN102389834B reports the process of calcining the catalyst micropowder produced during the MTO reaction to remove carbon deposits, and separating the molecular sieve from the binder, filler, etc. by crushing. The separated binder and matrix carrier are also used as binders in the new catalyst.

[0009] Patent CN112708761A reports a method for recovering phosphorus and aluminum from spent MTO catalysts. Patent CN109455747A reports a method for preparing alumina and phosphorus-containing ternary compound fertilizers from spent MTO catalysts.

[0010] Apart from this, no reports have been found on recycling technologies that convert spent MTO catalysts into molecular sieve-type special functional materials. Summary of the Invention

[0011] This application provides a method for preparing SAPO eutectic molecular sieves using an MTO catalyst, such as a method for preparing SAPO-18 / SAPO-34 eutectic molecular sieves. This method has the advantages of being simple and easy to mass-produce industrially. The SAPO eutectic molecular sieve prepared by this invention can be used in methanol-to-olefins (MTO) reactions and in the production of nitrogen oxides (NOx) from motor vehicle exhaust. x It has broad application prospects in processes such as removal, catalytic production of methanol from methane, and gas adsorption separation.

[0012] One aspect of this application provides a method for preparing SAPO eutectic molecular sieves, comprising the following steps:

[0013] (1) Mix the raw materials containing organic amine R, water, silicon source, aluminum source and phosphorus source, stir and age to obtain synthetic gel;

[0014] The molar ratio of each component in the synthetic gel is SiO2:Al2O3:P2O5:R:H2O = 0-1.0:1.0:0.7-1.5:0.5-10.0:25.0-400.0;

[0015] The raw materials include an MTO catalyst; the MTO catalyst provides at least a portion of a silicon source, an aluminum source, and a phosphorus source.

[0016] (2) The synthesized gel is crystallized and separated to obtain the SAPO eutectic molecular sieve;

[0017] The number of moles of silicon source is calculated as the number of moles of SiO2; the number of moles of aluminum source is calculated as the number of moles of Al2O3; the number of moles of phosphorus source is calculated as the number of moles of P2O5; the number of moles of template agent is calculated as the number of moles of its own R; and the number of moles of water is calculated as the number of moles of its own H2O.

[0018] Optionally, the molar ratio of each component in the synthetic gel is SiO2:Al2O3:P2O5:H2O:R = 0.1:1:1.0:50:2.0, 0.1:1:1.0:50:2.0, or 0.15:1:0.95:60:3.0.

[0019] 0.2:1:0.9:70:3.0, 0.25:1:0.85:80:3.0, 0.3:1:0.8:90:2.0, 0.35:1:1.05:100:2.0, 0.4:1:1.1:30:2.0, 0.45:1:1.15:40:2.0, 0.5:1:1.2:75:2.5, 0.4:1:1.2:55:3.0, 0.5:1:1.15:65:3, 0.3:1:1. 1:45:3.0, 0.2:1:1.05:85:3.0, 0.1:1:1.0:35:3.0, 0.15:1:0.95:95:3.0, 0.25:1:0.9:60:3.0, 0.35:1:0.85:40:3.0, 0.45:1:0.8:65:3.0, 0.25:1:1.0:55:2.0, 0.3:1:0.9:75:3.5, and the range between any two ratios.

[0020] Optionally, the SAPO eutectic molecular sieve is a SAPO-18 / SAPO-34 eutectic molecular sieve.

[0021] Optionally, the aluminum source is selected from one or a mixture of several of aluminum isopropoxide, boehmite, alumina, aluminum hydroxide, and sodium aluminate;

[0022] The silicon source is selected from one or a mixture of several of tetraethyl orthosilicate, silica sol, silica gel, silica fume and metakaolin.

[0023] The phosphorus source is selected from one or a mixture of several of orthophosphoric acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, organophosphorus compounds or phosphorus oxides;

[0024] The organic amine R is selected from any one, two or more of N,N-diisopropylethylamine (DiEA), N-methyldiethanolamine (MDEA), tetraethylammonium hydroxide (TEAOH), triethylamine (TEA), di-n-propylamine (DPA), diisopropylamine (DiPA), n-butylamine (BTA), and morpholine (MP).

[0025] Optionally, in step (1), the dry basis amount of the MTO catalyst added is 10 to 80% of the total dry basis mass of the inorganic matter in the synthetic gel.

[0026] Optionally, whether step (1) requires the addition of silicon, aluminum, and phosphorus sources other than the MTO catalyst depends on whether the silicon, aluminum, and phosphorus sources provided by the MTO catalyst meet the required amounts of silicon, aluminum, and phosphorus sources in the synthesized gel: that is, if the amount of MTO catalyst does not meet the required amounts of silicon, aluminum, and phosphorus sources in the synthesized gel, then the corresponding silicon, aluminum, and phosphorus sources need to be added; if the amount of MTO catalyst already meets the required amounts of silicon, aluminum, and phosphorus sources in the synthesized gel, then no additional addition is required.

[0027] Optionally, in step (1), in addition to the MTO catalyst, the raw material is supplemented with at least one of a silicon source, an aluminum source, and a phosphorus source;

[0028] Preferably, with a molar amount of Al2O3 of 1, the amount of silicon source added is Al2O3:SiO2 = 1:0.1-0.5;

[0029] Preferably, with a molar amount of Al2O3 of 1, the amount of phosphorus source added is Al2O3:P2O5 = 1:0.8-1.2;

[0030] Preferably, with a molar amount of Al2O3 of 1, the amount of organic amine R added is Al2O3:R = 1:1.0-3.0;

[0031] Preferably, with a molar amount of Al2O3 of 1, the amount of water added is Al2O3:H2O = 1:30-100.

[0032] Optionally, in step (1), the aging process includes:

[0033] The MTO catalyst, water, and phosphorus source are mixed for aging; or the MTO catalyst, water, and organic amine R are mixed for aging.

[0034] Optionally, in step (1), the aging process involves stirring at 10-100°C for 6-24 hours.

[0035] Optionally, in step (2), the crystallization temperature is 120–200°C;

[0036] The crystallization time is 6-120 hours.

[0037] Optionally, in step (2), the crystallization temperature is 130–180°C;

[0038] The crystallization time is 12-72 hours.

[0039] Optionally, in step (1), SAPO eutectic molecular sieve seed crystals are added to the raw materials;

[0040] Preferably, the amount of seed crystals added is 0.5% to 4% of the total dry mass of inorganic substances in the synthetic gel.

[0041] Optionally, the SAPO eutectic molecular sieve seed crystal added in step (1) is in the form of raw powder containing template agent, or is a molecular sieve with template agent removed by calcination.

[0042] Optionally, the MTO catalyst is a fresh catalyst or a spent MTO catalyst discharged from an industrial plant.

[0043] Optionally, the MTO waste catalyst needs to be roasted at high temperature before use to remove any residual carbon that may be present.

[0044] As one embodiment, this application provides a method for preparing SAPO eutectic molecular sieves using spent MTO catalyst, the preparation process including the following steps:

[0045] 1) Mix the calcined MTO waste catalyst, organic amine R, and deionized water in a certain proportion, stir at room temperature until the synthesis liquid is homogeneous, and continue aging for 6-24 hours.

[0046] 2) Add silicon source, aluminum source and phosphorus source to the homogeneous mixture formed in step 1), and continue stirring at room temperature until the mixture is homogeneous to obtain the desired synthetic gel;

[0047] The molar ratio of each component in the synthetic gel is SiO2:Al2O3:P2O5:R:H2O = 0-1.0:1.0:0.7-1.5:0.5-10.0:25.0-400.0;

[0048] 3) Transfer the gel obtained in step 2) into a high-pressure synthesis reactor and seal it. Perform hydrothermal crystallization at 120-200°C under autogenous pressure for 6-120 hours.

[0049] 4) After crystallization, the synthesized product from step 3) is rapidly cooled to room temperature, then the solid and liquid are separated, washed with deionized water, and dried to obtain SAPO eutectic molecular sieve.

[0050] As one embodiment, this application provides a method for preparing SAPO eutectic molecular sieves using spent MTO catalyst, the preparation process including the following steps:

[0051] 1) Mix the calcined MTO waste catalyst, phosphorus source, and deionized water in a certain proportion, stir at room temperature until the synthesis liquid is homogeneous, and continue aging for 6-24 hours.

[0052] 2) Add silicon source, aluminum source and organic amine R to the homogeneous mixture formed in step 1), and continue stirring at room temperature until the mixture is homogeneous to obtain the desired synthetic gel;

[0053] The molar ratio of each component in the synthetic gel is SiO2:Al2O3:P2O5:R:H2O = 0-1.0:1.0:0.7-1.5:0.5-10.0:25.0-400.0;

[0054] 3) Transfer the gel obtained in step 2) into a high-pressure synthesis reactor and seal it. Perform hydrothermal crystallization at 130-180°C under autogenous pressure for 6-120 hours.

[0055] 4) After crystallization, the synthesized product from step 3) is rapidly cooled to room temperature, then the solid and liquid are separated, washed with deionized water, and dried to obtain SAPO eutectic molecular sieve.

[0056] As one implementation method, when preparing SAPO eutectic molecular sieves using MTO waste catalyst, whether to add silicon source, aluminum source and phosphorus source in step 2) depends on whether the amount of silicon source, aluminum source and phosphorus source in the total feed gel ratio is met; if the amount of silicon source, aluminum source and phosphorus source does not meet the amount of silicon source, aluminum source and phosphorus source in the gel ratio, then additional silicon source, aluminum source and phosphorus source need to be added; otherwise, no additional addition is required.

[0057] In one embodiment, the silicon source is one or a mixture of several of tetraethyl orthosilicate, silica sol, silica gel, silica fume and metakaolin.

[0058] The aluminum source is one or a mixture of several of aluminum isopropoxide, boehmite, alumina, aluminum hydroxide, and sodium aluminate;

[0059] The phosphorus source is one or a mixture of several of orthophosphoric acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, organophosphorus compounds or phosphorus oxides;

[0060] The organic amine R is selected from any one, two or more of N,N-diisopropylethylamine (DiEA), N-methyldiethanolamine (MDEA), tetraethylammonium hydroxide (TEAOH), triethylamine (TEA), di-n-propylamine (DPA), diisopropylamine (DiPA), n-butylamine (BTA), and morpholine (MP).

[0061] In one embodiment, when preparing SAPO eutectic molecular sieve using MTO waste catalyst, the preferred addition amount of silicon is Al2O3:SiO2 = 1:0.1-0.5; the preferred addition amount of phosphorus is Al2O3:P2O5 = 1:0.8-1.2; the preferred addition amount of organic amine R is Al2O3:R = 1:1.0-3.0; the preferred addition amount of water is Al2O3:H2O = 1:30-100; the preferred crystallization temperature is 130-180℃; and the preferred crystallization time is 12-72 hours.

[0062] According to another aspect of the invention, the application of SAPO eutectic molecular sieves prepared according to any of the above methods is provided in the methanol and / or dimethyl ether to olefins (MTO) reaction.

[0063] According to another aspect of the invention, the application of SAPO eutectic molecular sieves prepared according to any of the above methods in the treatment of nitrogen oxides in automobile exhaust is provided.

[0064] According to another aspect of the invention, the application of SAPO eutectic molecular sieves prepared according to any of the above methods in the catalytic reaction of methane to methanol is provided.

[0065] According to another aspect of the present invention, the application of SAPO eutectic molecular sieves prepared according to any of the above methods in the field of gas separation is provided.

[0066] The beneficial effects that this application may produce include at least the following:

[0067] 1) The method for preparing SAPO eutectic molecular sieves using MTO waste catalyst provided in this application can reduce the environmental pollution caused by MTO waste catalyst and reduce the production cost of catalyst, thus having good economic benefits.

[0068] 2) The preparation method of SAPO eutectic molecular sieve using MTO waste catalyst provided in this application is simple and conducive to large-scale industrial production.

[0069] 3) The preparation method of SAPO eutectic molecular sieve using MTO waste catalyst provided in this application has the advantage of high yield.

[0070] 4) The method for preparing SAPO eutectic molecular sieves using MTO waste catalyst provided in this application has the advantages of short crystallization time and high crystallinity. Attached Figure Description

[0071] Figure 1 Example Sample 1 # ~20 # X-ray powder diffraction pattern of the prepared SAPO-18 / SAPO-34 eutectic molecular sieve.

[0072] Figure 2 The image shows the X-ray powder diffraction pattern of sample S1.

[0073] Figure 3 The X-ray powder diffraction pattern of sample S3 is shown for comparison. Detailed Implementation

[0074] The present application is further illustrated below with reference to specific embodiments. The following descriptions are merely a few embodiments of the present application and are not intended to limit the present application in any way. Although the present application discloses preferred embodiments as follows, they are not intended to limit the present application. Any modifications or variations made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

[0075] Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased commercially and used directly without any special treatment.

[0076] The product analysis method in the embodiments of the present invention is as follows:

[0077] X-ray powder diffraction (XRD) phase analysis was performed using an X'Pert PRO X-ray diffractometer from PANalytical, Netherlands, with a Cu target, a Kα radiation source (λ = 0.15418 nm), a voltage of 40 kV, and a current of 40 mA.

[0078] Example 1: Sample 1 # Preparation

[0079] First, 1.14 g of spent MTO catalyst (its composition is shown in Table 1) was added to 39.89 g of deionized water and stirred until homogeneous. Then, 11.84 g of 80% H3PO4 solution was added, and stirring continued for 24 hours. Next, 18.11 g of aluminum isopropoxide and 1.13 g of SAPO-18 / SAPO-34 eutectic seed crystals were added, followed by the addition of 13.1 g of 99% DIEA solution while stirring. Stirring continued until a homogeneous gel was formed, which is the synthesized gel. The gel was placed in a stainless steel reactor with a polytetrafluoroethylene liner and sealed. The temperature was raised to 180℃ for crystallization for 48 hours. The resulting solid product was centrifuged, washed with deionized water until neutral, dried in air at 120℃, and finally calcined in a muffle furnace at 600℃ for 5 hours to obtain 11.7 g of SAPO-18 / SAPO-34 eutectic molecular sieve, designated as sample 1. # Sample 1 prepared # The types of raw materials, molar ratios, amount of MTO waste catalyst, amount of seed crystals, crystallization temperature, crystallization time, and yield in the synthetic gel are shown in Table 1.

[0080] Example 2: Sample 2 # Preparation

[0081] First, 1.71g of spent MTO catalyst was added to 47.37g of deionized water and stirred until homogeneous. Then, 17.9g of 99% MDEA solution was added, and stirring continued for 12 hours. Next, 6.04g of 70% boehmite, 11.01g of 80% H3PO4 solution, and 0.86g of SAPO-18 / SAPO-34 eutectic seed crystals were added, and stirring continued until a homogeneous gel was formed, which was the synthesized gel. The gel was placed in a stainless steel reactor with a PTFE liner and sealed. The mixture was heated to 180℃ and crystallized for 60 hours. The resulting solid product was centrifuged, washed with deionized water until neutral, dried in air at 120℃, and finally calcined in a muffle furnace at 600℃ for 5 hours to obtain 10.65g of SAPO-18 / SAPO-34 eutectic molecular sieve, designated as sample 2. # Sample 2 prepared # The types of raw materials, molar ratios, amount of MTO waste catalyst, amount of seed crystals, crystallization temperature, crystallization time, and yield in the synthetic gel are shown in Table 1.

[0082] Example 3: Sample 3 # ~20 # Preparation

[0083] Sample 3 # ~8 # The SAPO-18 / SAPO-34 eutectic molecular sieve was synthesized using a single template agent system; Sample 9 # ~20 # The SAPO-18 / SAPO-34 eutectic molecular sieve was synthesized using a dual template agent system; Sample 3 # ~20 # The specific preparation process can be carried out according to Example 1 or Example 2; the types of raw materials, molar ratios, amount of MTO waste catalyst fed, amount of seed crystals, crystallization conditions and product yield are shown in Table 1.

[0084] Example 4: Preparation of Sample S1

[0085] The specific ingredient preparation process is the same as that for sample 1 in Examples 1-20. # ~20 # The difference lies in the preparation method: no seed crystals are added during the gel synthesis step. The synthesis ratio is 0.1SiO2. a Al2O3 h :1.0P2O5 o The resulting sample is denoted as sample S1, and the solution is 50H2O:2.0DiEA.

[0086] Example 5: Preparation of Sample S2

[0087] The specific ingredient preparation process is the same as that for sample 1 in Examples 1-20. # ~20 # The preparation method differs from the previous one in that the spent MTO catalyst in the synthesis raw materials is replaced with fresh MTO catalyst. Otherwise, all other aspects are identical. The synthesis ratio is 0.3SiO2. b Al2O3 k 1.1P2O5 q The mixture of 45H2O, 1.0TEA, and 2.0DiPA was used to obtain the sample, which was denoted as sample S2.

[0088] Comparative Example 1: Preparation of Comparative Sample S3

[0089] The specific ingredient preparation process differs from that in Examples 1-3 and Comparative Examples 1-2 in that all raw materials are added at once, without any aging process; otherwise, everything else (including the order of ingredient addition) is completely identical. The synthesis ratio is 0.2SiO2. c Al2O3 j 1.05P2O5 q The mixture of 85H2O, 0.5BTA, and 2.5MP was used to obtain the control sample S3.

[0090] Sample 1 # ~20 # Characterization analysis of samples S1, S2 and S3

[0091] X-ray diffraction method and sample 1 were used # ~20 # The phase composition of samples S1, S2 and S3 was analyzed.

[0092] The results showed that samples 1 prepared in Examples 1, 2, and 3 were... # ~20 # All are high-purity, high-crystallinity, and high-yield SAPO-18 / SAPO-34 eutectic molecular sieves, with typical examples being... Figure 1 Medium sample 1 # XRD pattern.

[0093] The XRD pattern of sample S1 is as follows Figure 2As shown, although the purity of sample S1 was guaranteed, the crystallinity was slightly reduced, and the yield also decreased to 53%. It is evident that in the synthesis of SAPO-18 / SAPO-34 eutectic molecular sieves using MTO waste catalyst according to this application, while the addition of seed crystals is not essential, it can accelerate the crystallization rate of SAPO-18 / SAPO-34 eutectic molecular sieves. This is key to the rapid and high-yield preparation of SAPO-18 / SAPO-34 eutectic molecular sieves using MTO waste catalyst.

[0094] XRD pattern of sample S2 and Figure 1 and Figure 2 The same applies, and will not be repeated here. Furthermore, the synthesized SAPO-18 / SAPO-34 eutectic molecular sieve exhibits high crystallinity and yield. This indicates that the method of the present invention for preparing SAPO-18 / SAPO-34 eutectic molecular sieve using methanol-to-olefins (MTO) catalyst is applicable to both spent and fresh MTO catalysts.

[0095] The XRD pattern of sample S3 is shown below. Figure 3 As shown, its diffraction analysis results are the same as those of the previous analysis. Figure 1 and Figure 2 The XRD diffraction patterns differ. In the XRD diffraction pattern of the control sample S3, in addition to the diffraction peaks of SAPO-18 / SAPO-34, a diffraction peak also appeared at 2θ = 7.44 (black pentagram). This indicates that the control sample S3 is a miscible phase of SAPO-5 molecular sieve and SAPO-18 / SAPO-34 molecular sieve. This also demonstrates that in the method of preparing SAPO-18 / SAPO-34 molecular sieve using methanol-to-olefins (MTO) catalyst of the present invention, the aging process in the batching step is a necessary step to obtain pure-phase SAPO-18 / SAPO-34 eutectic molecular sieve.

[0096] Table 1. Molecular sieve synthesis ingredients and crystallization conditions

[0097]

[0098] Note * Silicon source: a Tetraethyl orthosilicate; b Silica sol; c Silicone gel; d Silica; e Kaolinite.

[0099] Note ** Aluminum source: h Aluminum isopropoxide; i pseudoboehmite; j Alumina; k Aluminum hydroxide; l Sodium aluminate.

[0100] Note *** Phosphorus source: o orthophosphoric acid; p Ammonium hydrogen phosphate; q Ammonium dihydrogen phosphate.

[0101] Note **** Organic amines R: N,N-diisopropylethylamine (DiEA), N-methyldiethanolamine (MDEA), tetraethylammonium hydroxide (TEAOH), triethylamine (TEA), di-n-propylamine (DPA), diisopropylamine (DiPA), n-butylamine (BTA), morpholine (MP).

[0102] Note ***** The composition of the spent MTO catalyst is: SiO2% = 26.4%, Al2O3% = 51.2%, P2O5% = 21.1%.

[0103] Note ****** Yield = Sample / (MTO waste catalyst + SiO2 + Al2O3 + P2O5 + seed) * 0.85 * 100%.

[0104] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A method for preparing SAPO eutectic molecular sieves, characterized in that, Includes the following steps: 1) Mix the MTO catalyst, organic amine R, and deionized water in a certain proportion, stir evenly, and continue aging for 6-24 hours; 2) Add silicon source, aluminum source and phosphorus source other than MTO catalyst to the mixture in step 1), and stir at room temperature until the mixture is homogeneous. 3) Add SAPO eutectic molecular sieve seed crystals to the homogeneous mixture formed in step 2), stir until homogeneous, and obtain the desired synthetic gel; The molar ratio of each component in the synthetic gel is SiO2: Al2O3: P2O5: R: H2O = 0-1.0: 1.0: 0.7-1.5: 0.5-10.0: 25.0-400.0, and the content of SiO2 is not zero; The amount of seed crystals added is 0-5% of the total dry weight of inorganic matter in the synthetic gel, and the content of seed crystals is not zero. 4) Transfer the gel obtained in step 3) into a high-pressure synthesis reactor and seal it. Perform hydrothermal crystallization at 120~200℃ under autogenous pressure for 6~120 hours. 5) After crystallization, the synthesis vessel is rapidly cooled to room temperature, followed by solid-liquid separation, washing with deionized water, and drying to obtain SAPO eutectic molecular sieve; or Includes the following steps: 1) Mix the MTO catalyst, phosphorus source, and deionized water in a certain proportion, stir evenly at room temperature, and continue aging for 6-24 hours. 2) Add silicon source, aluminum source and organic amine R (excluding MTO catalyst) to the homogeneous mixture formed in step 1), and continue stirring at room temperature until the mixture is homogeneous; 3) Add SAPO eutectic molecular sieve seed crystals to the mixture formed in step 2), and stir at room temperature until the mixture is homogeneous to obtain the desired synthetic gel; The molar ratio of each component in the synthetic gel is SiO2: Al2O3: P2O5: R: H2O = 0-1.0: 1.0: 0.7-1.5: 0.5-10.0: 25.0-400.0, and the content of SiO2 is not zero; The amount of seed crystals added is 0-5% of the total dry weight of inorganic matter in the synthetic gel, and the content of seed crystals is not zero. 4) Transfer the gel obtained in step 3) into a high-pressure synthesis reactor and seal it. Perform hydrothermal crystallization at 120~200℃ under autogenous pressure for 6~120 hours. 5) After crystallization, the synthesis vessel is rapidly cooled to room temperature, the solid and liquid are separated, washed with deionized water, and dried to obtain SAPO eutectic molecular sieve.

2. The method according to claim 1, characterized in that, The SAPO eutectic molecular sieve is a SAPO-18 / SAPO-34 eutectic molecular sieve.

3. The method according to claim 1, characterized in that, The aluminum source is selected from one or a mixture of several of aluminum isopropoxide, boehmite, alumina, aluminum hydroxide and sodium aluminate; The silicon source is selected from one or a mixture of several of tetraethyl orthosilicate, silica sol, silica gel, silica fume and metakaolin. The phosphorus source is selected from one or a mixture of several of orthophosphoric acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, organophosphorus compounds or phosphorus oxides; The organic amine R is selected from any one or a mixture of two or more of N,N-diisopropylethylamine (DIEA), N-methyldiethanolamine (MDEA), tetraethylammonium hydroxide (TEAOH), triethylamine (TEA), di-n-propylamine (DPA), diisopropylamine (DIPA), n-butylamine (BTA), and morpholine (MP).

4. The method according to claim 1, characterized in that, In step 1), the dry basis amount of the MTO catalyst added is 10-80% of the total dry basis mass of inorganic matter in the synthetic gel.

5. The method according to claim 1, characterized in that, The amount of seed crystals added is 0.5-4% of the total dry mass of inorganic matter in the synthetic gel.

6. The method according to claim 1, characterized in that, The SAPO eutectic molecular sieve seed crystals added in step 3) are either in the form of raw powder containing template agent, or molecular sieves with template agent removed by calcination.

7. The method according to claim 1, characterized in that, The MTO catalyst is either a fresh catalyst or a spent MTO catalyst discharged from an industrial plant.

8. The method according to claim 7, characterized in that, The MTO waste catalyst needs to be roasted at high temperature before use to remove any residual carbon that may be present.

9. The use of the SAPO eutectic molecular sieve prepared by the method of any one of claims 1-8 in the reaction of methanol and / or dimethyl ether to olefins.

10. The application of the SAPO eutectic molecular sieve prepared by the method according to any one of claims 1-8 in the removal reaction of nitrogen oxides in motor vehicle exhaust.

11. The application of the SAPO eutectic molecular sieve prepared by the method according to any one of claims 1-8 in the catalytic process of methane to methanol.

12. The application of the SAPO eutectic molecular sieve prepared by the method according to any one of claims 1-8 in the gas adsorption and separation process.

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