阅读说明：本技术 Sapo复合分子筛及其制备方法和其用途 (SAPO composite molecular sieve, and preparation method and application thereof ) 是由 丁佳佳 刘红星 赵昱 陆贤 于 2020-06-01 设计创作，主要内容包括：本发明公开了一种SAPO复合分子筛及其制备方法和其用途。所述的SAPO复合分子筛为SAPO-34/SAPO-18复合分子筛,晶体形貌呈板状结构,长为0.1～2.0微米,宽为0.1～2.0微米,厚度为0.04～0.4微米。其制备方法包括：将用于合成SAPO-34分子筛的原料与用于合成SAPO-18分子筛的原料中的其一制成凝胶,另一制成含初始结构的分子筛浆料,然后将两者混合,在水热晶化条件下制备出SAPO复合分子筛。将该复合分子筛作为催化剂用于甲醇制烯烃工艺中,能够提高双烯收率,且催化剂具有较好的稳定性。(The invention discloses an SAPO composite molecular sieve, a preparation method and application thereof. The SAPO composite molecular sieve is an SAPO-34/SAPO-18 composite molecular sieve, the crystal appearance is of a plate-shaped structure, the length is 0.1-2.0 micrometers, the width is 0.1-2.0 micrometers, and the thickness is 0.04-0.4 micrometers. The preparation method comprises the following steps: preparing one of the raw materials for synthesizing the SAPO-34 molecular sieve and the raw materials for synthesizing the SAPO-18 molecular sieve into gel, preparing the other one into molecular sieve slurry containing an initial structure, mixing the two, and preparing the SAPO composite molecular sieve under the hydrothermal crystallization condition. The composite molecular sieve is used as a catalyst in a process for preparing olefin from methanol, so that the yield of diene can be improved, and the catalyst has good stability.)

1. The SAPO composite molecular sieve is an SAPO-34/SAPO-18 composite molecular sieve, the crystal appearance of the SAPO composite molecular sieve is a plate-shaped structure, the length of the SAPO composite molecular sieve is 0.1-2.0 micrometers, the width of the SAPO composite molecular sieve is 0.1-2.0 micrometers, and the thickness of the SAPO composite molecular sieve is 0.04-0.4 micrometers.

2. The composite molecular sieve of claim 1, wherein: the SAPO composite molecular sieve has a plate-shaped crystal morphology, the length of the SAPO composite molecular sieve is 0.5-1.0 micron, the width of the SAPO composite molecular sieve is 0.5-1.0 micron, and the thickness of the SAPO composite molecular sieve is 0.1-0.2 micron.

3. The composite molecular sieve of claim 1, wherein: in the SAPO composite molecular sieve, the mass ratio of SAPO-34 to SAPO-18 is 2-15: 85-98.

4. The composite molecular sieve of claim 1, wherein: in the SAPO composite molecular sieve, the mass ratio of SAPO-18 to SAPO-34 is 2-15: 85-98.

5. A preparation method of the SAPO composite molecular sieve comprises the following steps:

preparing one of the raw materials for synthesizing the SAPO-34 molecular sieve and the raw materials for synthesizing the SAPO-18 molecular sieve into gel, preparing the other one into molecular sieve slurry containing an initial structure, mixing the two, and preparing the SAPO composite molecular sieve under the hydrothermal crystallization condition; wherein the solid content of the molecular sieve slurry containing the initial structure accounts for 30-60% by mass fraction.

6. The method of claim 5, wherein: the mass content of the corresponding molecular sieve in the molecular sieve slurry containing the initial structure is 10-100%, preferably 20-95%, and the grain size is 0.1-1.0 micron.

7. The method of claim 5 or 6, wherein: the dosage of the gel and the molecular sieve slurry containing the initial structure is such that the mass fraction of the solid content introduced by the molecular sieve slurry containing the initial structure in the total solid content of the gel and the slurry is 1-30%, preferably 3-25%.

8. The method of claim 5, wherein: the raw materials for synthesizing the SAPO-34 molecular sieve comprise: a first silicon source, a first aluminum source, a first phosphorus source, a first template agent and water;

wherein the process of preparing the gel from the raw materials for synthesizing the SAPO-34 molecular sieve is as follows: mixing the first aluminum source, the first silicon source, the first phosphorus source, the first template agent and water to prepare gel, wherein Al is used₂O₃：SiO₂：P₂O₅：R1：H₂The molar ratio of O is 1: (0.2-0.8): (0.3-2.0): (1-8): (20 to 100), preferably 1: (0.2-0.6): (0.6-1.2): (3-6): (30-80), wherein the used template R1 is a mixed template of tetraethyl ammonium hydroxide and triethylamine, and the molar ratio of the tetraethyl ammonium hydroxide to the triethylamine is 1: (1-3).

9. The method of claim 5, wherein: the raw materials for synthesizing the SAPO-34 molecular sieve comprise: a first silicon source, a first aluminum source, a first phosphorus source, a first template agent and water;

the process for preparing the molecular sieve slurry containing the initial structure from the raw materials for synthesizing the SAPO-34 molecular sieve is as follows: the process of claim 7, wherein the raw material for synthesizing SAPO-34 molecular sieve is made into gel, and the gel is crystallized to obtain molecular sieve slurry containing initial structure, wherein the crystallization conditions are as follows: the temperature is 150-210 ℃, preferably 180-200 ℃, and the time is 3-24 hours, preferably 8-18 hours.

10. A method according to claim 5 or 9, characterized by: the raw materials for synthesizing the SAPO-18 molecular sieve comprise: a first silicon source, a first aluminum source, a first phosphorus source, a first template agent and water;

wherein the process of preparing the gel from the raw materials for synthesizing the SAPO-18 molecular sieve is as follows: mixing the second aluminum source, the second silicon source, the second phosphorus source, the second template agent and water to prepare gel, wherein Al is used₂O₃：SiO₂：P₂O₅：R2：H₂The molar ratio of O is 1: (0.05-1.0): (0.1-1.0): (1-8): (10 to 100), preferably 1: (0.1-0.8): (0.2-0.9): (2-6): (30-80); the template R2 is at least two of N, N-diisoethylpropylamine, tetraethylammonium hydroxide and triethylamine.

11. The method of claim 5 or 8, wherein: the raw materials for synthesizing the SAPO-18 molecular sieve comprise: a first silicon source, a first aluminum source, a first phosphorus source, a first template agent and water;

the process for preparing the molecular sieve slurry containing the initial structure from the raw materials for synthesizing the SAPO-18 molecular sieve is as follows: the process of claim 9, wherein the raw material for synthesizing SAPO-18 molecular sieve is made into gel, and said gel is crystallized to obtain molecular sieve slurry containing initial structure, wherein the crystallization conditions are as follows: the temperature is 150-190 ℃, preferably 160-190 ℃, and the time is 5-24 hours.

12. The method of claim 5, wherein: the crystallization conditions of the mixture of the gel and the molecular sieve slurry containing the initial structure under the hydrothermal condition are as follows: the temperature is 160-230 ℃, preferably 180-200 ℃, and the time is 8-35 hours, preferably 10-30 hours.

13. Use of a SAPO composite molecular sieve according to any one of claims 1 to 4 or a SAPO composite molecular sieve prepared by a method according to any one of claims 5 to 12 in a reaction for producing olefins from oxygenates.

Technical Field

The invention relates to an SAPO composite molecular sieve and a preparation method thereof, in particular to an SAPO-34/SAPO-18 composite molecular sieve and a preparation method thereof, which are particularly suitable for the reaction of preparing olefin from oxygen-containing compounds.

Background

In 1984, united states of america united carbides (UCC) invented a silicoaluminophosphate molecular sieve (SAPO molecular sieve for short) with a pore size of about 0.4 nm. The SAPO molecular sieve is prepared from AlO₄、SiO₄And PO₄Crystal network structure composed of tetrahedrons, pore channels in the crystal being formed by Si⁴⁺Substituted P⁵⁺Or Al³⁺The resulting acidity can be either replaced with a metal to produce acidity. Wherein the crystal structure of the SAPO-34 molecular sieve is a CHA type structure, the basic composition structural units of the SAPO-34 molecular sieve are double six-membered rings and CHA cages, the crystal structure of the SAPO-18 molecular sieve is an AEI structure, and the microporous pore channel structure of the molecular sieve is similar to the CHA structure. Among SAPO series of molecular sieves, SAPO-34 molecular sieve is widely used in modern petroleum processing industry because of its good thermal and hydrothermal stability, moderate acidity, high specific surface area and highly ordered microporous channels. The molecular sieve is most attractive when applied to Methanol To Olefin (MTO) reaction, the conversion rate of methanol can reach 100 percent, the selectivity of ethylene and propylene can exceed 80 percent, and C is₅ ⁺The content of the components is small and almost no aromatic hydrocarbon is generated. The SAPO-18 molecular sieve has weaker surface acidity, and shows excellent catalytic performance and longer catalyst stability in the MTO process. At present, the shape of the SAPO-34 molecular sieve prepared under the conventional conditions is cubic, and the grain size is several microns. In addition, the narrow and long microporous pore channels of the molecular sieve present serious shape-selective limitations, which on one hand prevent the raw material molecules from contacting with the active centers in the pore channels and on the other hand prevent the raw material molecules from contacting with the active centers in the pore channelsThe diffusion and mass transfer of reactants, intermediate transition products and final products are limited, and the catalyst is easy to deactivate due to the blockage of pore channels caused by carbon deposition.

In order to solve the problems of easy deactivation and reduced catalytic performance of the catalyst caused by the oversize molecular sieve crystal grains, researchers solve the problems from the following two aspects: firstly, the grain size is reduced, the reduction of the grain size can shorten the diffusion path of reactants, intermediate transition state products and final products, and can prolong the stability of the catalyst; another method is to prepare a novel molecular sieve material combining the advantages of various pore channels, namely a hierarchical pore structure molecular sieve. According to the structure type of the pore channel, the hierarchical pore molecular sieves can be divided into the following two types: one is a micropore-micropore composite molecular sieve formed by two-phase cocrystallization molecular sieves, and the material consists of two or more than two composite micropore pore canals; the other type is a mesoporous/macroporous-microporous composite molecular sieve, the material has a microporous channel system and a mesoporous/macroporous channel system, the diffusion performance of the material can be greatly improved, the catalytic performance of the material is improved, and the material shows good catalytic conversion performance in reactions involving macromolecules and reactions requiring rapid diffusion.

The method comprises the steps of changing an aluminum source, enabling the aluminum source to react with a template agent and phosphoric acid rapidly to form a colloid in a metastable state, using a liquid silicon source to form a precursor solution with higher concentration, adding the template agent with good solubility, introducing ultrasound or microwaves, controlling aging conditions and the like, and reducing the grain size of the molecular sieve, but the problems of difficult separation, reduced molecular sieve yield and the like are caused after the grain size of the molecular sieve is reduced to a nanometer level. In addition, a mesoporous template is added into a gel system, and then a composite pore structure molecular sieve containing a mesoporous structure can be prepared by a hydrothermal synthesis preparation method, and Choi and the like report that an AlPO with a mesoporous structure is synthesized by one-step hydrothermal synthesis by using a silanized long-chain alkyl quaternary ammonium salt as the template₄N-series molecular sieves (Choi M, Srivastava R, Ryoo R.chemical Communications, 2006; (42): 4380-4382.); then, Danilina, chrysolel and the like take multifunctional long-chain organosilicon as a silicon source to respectively hydrothermally synthesize SAPO-5(Danilina N, Krumeich F, van Bokh) with a hierarchical pore structureJournal of Catalysis,2010,272(1):37-43.) and SAPO-34 molecular sieves (celluloid, royal jelly, butandin, et al, advanced chemical bulletin, 2010; 31(9):1693-1696.). However, the mesoporous template used in these methods is difficult to prepare and expensive, which affects the synthesis cost of the molecular sieve. In order to solve the problem, Ren et al modify the conventional SAPO-34 molecular sieve by acid treatment to obtain the SAPO-34 molecular sieve with the hierarchical pore structure (Ren S, Liu G, Wu X, et al Chinese Journal of Catalysis, 2017; 38(1): 123-; 130.), the method firstly synthesizes the conventional SAPO-34 molecular sieve by a hydrothermal method, and then carries out modification treatment on the conventional SAPO-34 molecular sieve by organic acid after cooling, washing, separating and drying, thereby obtaining the SAPO-34 molecular sieve with the hierarchical pore structure, and the molecular sieve shows good catalytic performance in the reaction of preparing olefin from methanol. However, the method firstly needs to separate and dry the conventional molecular sieve, and then can carry out modification treatment, so the operation steps are long, and the loss of the molecular sieve is more after the molecular sieve is separated for many times.

The SAPO-18 and SAPO-34 molecular sieves are compounded to form the eutectic SAPO molecular sieve, the eutectic molecular sieve has the pore canal and the acidity of two crystal phase structures, and often shows better performance than a single molecular sieve when used for catalytic reaction, and can effectively solve the problems of low catalytic activity and stability and the like of the single molecular sieve caused by single pore diameter. CN101076401A discloses a silicoaluminophosphate molecular sieve comprising intergrowth of CHA and AEI structures, which is mainly used for determining the ratio of AEI to CHA. CN103878018A discloses a method for preparing a small-grain SAPO-18/SAPO-34 eutectic molecular sieve, which is prepared by adding a crystal growth inhibitor into a crystallization liquid, and is granular with the shape of less than 1 micron. CN103833047A discloses a SAPO-5/SAPO-18/SAPO-34 intergrowth composite molecular sieve and a preparation method thereof, the composite molecular sieve obtained by the method has the grain size of 3-10 microns, and has the typical sheet layer structure of the SAPO-5 molecular sieve and the SAPO-18 molecular sieve and the cubic structure of the SAPO-34 molecular sieve.

In prior art oxygenate to olefin catalysts, molecular sieves, matrices, binders, and the like are incorporated into catalyst microspheres. The molecular sieve is used as an active center required by the reaction and is a key component of the catalyst, and the morphology and the pore structure of the molecular sieve can influence the diffusion and mass transfer of reactants, intermediate transition products and final products, so that the conversion of raw materials, the composition of the products and the stability of the catalyst are influenced. The technology for preparing olefin from methanol is developed to date, the yield of diene (ethylene and propylene) reaches 80-83%, and on the basis, if the yield is only improved by 1%, the yield can be increased by about 8000 tons of low-carbon olefin for an industrial device with annual treatment capacity of 180 ten thousand tons of methanol, and the economic benefit can be increased by 8000 thousands. Therefore, if a molecular sieve with more excellent catalytic performance can be developed under the conditions of reducing the preparation cost and simplifying the operation procedure, the catalytic performance of olefin preparation from oxygen-containing compounds is improved, and the method has important practical significance for improving the profit level of production enterprises.

Disclosure of Invention

The invention provides a novel SAPO composite molecular sieve, a preparation method thereof and application thereof in reaction for preparing olefin from oxygen-containing compounds. The composite molecular sieve is used as a catalyst in a process for preparing olefin from methanol, can improve the yield of diene, and has better stability.

The invention provides an SAPO composite molecular sieve, which is an SAPO-34/SAPO-18 composite molecular sieve, wherein the crystal appearance of the SAPO composite molecular sieve is a plate-shaped structure, the length of the SAPO composite molecular sieve is 0.1-2.0 micrometers, the width of the SAPO composite molecular sieve is 0.1-2.0 micrometers, and the thickness of the SAPO composite molecular sieve is 0.04-0.4 micrometer.

In the technical scheme, the SAPO composite molecular sieve has a plate-shaped crystal morphology, the length of the SAPO composite molecular sieve is 0.5-1.0 micron, the width of the SAPO composite molecular sieve is 0.5-1.0 micron, and the thickness of the SAPO composite molecular sieve is 0.1-0.2 micron.

In the technical scheme, the crystal morphology of the SAPO composite molecular sieve is of a plate-shaped structure, and the ratio of the length to the height of the SAPO composite molecular sieve is 2-5: 1, the ratio of width to height is 2-5: 1, the ratio of the length to the width is 1-2: 1.

in the technical scheme, in the SAPO composite molecular sieve, the mass ratio of SAPO-34 to SAPO-18 is 2-15: 85-98.

In the technical scheme, in the SAPO composite molecular sieve, the mass ratio of SAPO-18 to SAPO-34 is 2-15: 85-98.

The second aspect of the present invention provides a preparation method of a SAPO composite molecular sieve, comprising:

preparing one of the raw materials for synthesizing the SAPO-34 molecular sieve and the raw materials for synthesizing the SAPO-18 molecular sieve into gel, preparing the other one into molecular sieve slurry containing an initial structure, mixing the two, and preparing the SAPO composite molecular sieve under the hydrothermal crystallization condition; wherein the solid content of the molecular sieve slurry containing the initial structure accounts for 30-60% by mass fraction.

In the above technical scheme, the mass content of the corresponding molecular sieve in the molecular sieve slurry containing the initial structure is 10% -100%, preferably 20% -95%, and the grain size is 0.1-1.0 micron. The corresponding molecular sieve is the same molecular sieve corresponding to the raw material for synthesizing the molecular sieve, namely the corresponding molecular sieve in the molecular sieve slurry containing the initial structure prepared by adopting the raw material for synthesizing the SAPO-18 molecular sieve is SAPO-18, and the corresponding molecular sieve in the molecular sieve slurry containing the initial structure prepared by adopting the raw material for synthesizing the SAPO-34 molecular sieve is SAPO-34. The mass content of the corresponding molecular sieve in the molecular sieve slurry containing the initial structure is calculated by adopting XRD after the slurry is dried.

In the technical scheme, the use amount of the gel and the molecular sieve slurry containing the initial structure is such that the mass fraction of the solid content introduced by the molecular sieve slurry containing the initial structure in the total solid content of the gel and the slurry is 1-30%, preferably 3-25%.

In the technical scheme, the raw materials for synthesizing the SAPO-34 molecular sieve comprise: the device comprises a first silicon source, a first aluminum source, a first phosphorus source, a first template and water.

In the technical scheme, the process for preparing the gel from the raw materials for synthesizing the SAPO-34 molecular sieve comprises the following steps: mixing the first aluminum source, the first silicon source, the first phosphorus source, the first template agent and water to prepare gel, wherein Al is used₂O₃：SiO₂：P₂O₅：R1：H₂The molar ratio of O is 1: (0.2-0.8): (0.3-2.0): (1-8): (20 to 100), preferably 1: (0.2-0.6): (0.6-1.2): (3-6): (30-80), the template R1 is tetraethyl ammonium hydroxide and trisA mixed template agent of ethylamine, wherein the molar ratio of tetraethyl ammonium hydroxide to triethylamine is 1: (1-3).

In the technical scheme, the process for preparing the molecular sieve slurry containing the initial structure from the raw materials for synthesizing the SAPO-34 molecular sieve is as follows: by adopting the method, the raw materials for synthesizing the SAPO-34 molecular sieve are prepared into gel, and the gel is crystallized to obtain the molecular sieve slurry containing the initial structure. Wherein the crystallization conditions are as follows: the temperature is 150-210 ℃, preferably 180-200 ℃, and the time is 3-24 hours, preferably 8-18 hours.

In the technical scheme, the raw materials for synthesizing the SAPO-18 molecular sieve comprise: the device comprises a first silicon source, a first aluminum source, a first phosphorus source, a first template and water.

In the technical scheme, the process for preparing the gel from the raw materials for synthesizing the SAPO-18 molecular sieve comprises the following steps: mixing the second aluminum source, the second silicon source, the second phosphorus source, the second template agent and water to prepare gel, wherein Al is used₂O₃：SiO₂：P₂O₅：R2：H₂The molar ratio of O is 1: (0.05-1.0): (0.1-1.0): (1-8): (10 to 100), preferably 1: (0.1-0.8): (0.2-0.9): (2-6): (30-80). The template R2 is at least two of N, N-diisoethylpropylamine, tetraethylammonium hydroxide and triethylamine.

In the technical scheme, the process for preparing the molecular sieve slurry containing the initial structure from the raw materials for synthesizing the SAPO-18 molecular sieve is as follows: by adopting the method, the raw materials for synthesizing the SAPO-18 molecular sieve are prepared into gel, and the gel is crystallized to obtain the molecular sieve slurry containing the initial structure. Wherein the crystallization conditions are as follows: the temperature is 150-190 ℃, preferably 160-190 ℃, and the time is 5-24 hours.

In the above technical scheme, the crystallization conditions of the mixture of the gel and the molecular sieve slurry containing the initial structure under the hydrothermal condition are as follows: the temperature is 160-230 ℃, preferably 180-200 ℃, and the time is 8-35 hours, preferably 10-30 hours.

In the above technical solution, the first aluminum source or the second aluminum source is selected from at least one of aluminum isopropoxide, pseudo-boehmite or aluminum oxide, the first silicon source or the second silicon source is selected from at least one of tetraethoxysilane, white carbon black or silica sol, and the first phosphorus source or the second phosphorus source is selected from at least one of phosphoric acid, phosphate or phosphorous acid. The first aluminum source and the second aluminum source may be the same or different, the first silicon source and the second silicon source may be the same or different, and the first phosphorus source and the second phosphorus source may be the same or different.

In the technical scheme, after crystallization is finished, the crystallized product can be cooled, filtered, washed, dried, roasted and the like according to requirements.

The third aspect of the invention also provides an application of the SAPO composite molecular sieve in the reaction of preparing olefin from the oxygen-containing compound.

In the above technical scheme, the oxygen-containing compound is selected from methanol, ethanol, n-propanol, isopropanol and C_4-20Alcohol, methyl ethyl ether, dimethyl ether, diethyl ether, diisopropyl ether, formaldehyde, dimethyl carbonate, dimethyl ketone, preferably methanol or dimethyl ether. The olefin comprises ethylene, propylene, or a combination thereof.

In the technical scheme, when the SAPO composite molecular sieve catalyzes oxygen-containing compounds to prepare olefin, the temperature is 200-700 ℃, and the weight hourly space velocity is 1-1000 hours^-1The pressure is 0.5 kPa-5 MPa.

The SAPO composite molecular sieve has the shape of a small-crystal-grain plate, and has good activity, diene selectivity and stability when being used in the process of preparing olefin from methanol.

The method for preparing the SAPO composite molecular sieve adopts SAPO-34 gel and SAPO-18 slurry for mixing crystallization, or adopts SAPO-18 gel and SAPO-34 slurry for mixing crystallization, wherein the specific slurry is favorable for forming the small-grain composite molecular sieve with uniform grain size distribution, and the composite molecular sieve has good stability. The method for preparing the composite molecular sieve has simple operation process and easy implementation.

In addition, the technology for preparing olefin from methanol is developed to date, the yield of diene (ethylene + propylene) reaches 80-83%, and on the basis, if the yield is improved by 0.5%, the economic benefit is considerable for a ten-thousand-ton device. The SAPO composite molecular sieve of the invention is used as the active component of the catalyst in the process of preparing olefin from oxygen-containing compounds, shows good catalytic performance, can improve the yield of diene (ethylene + propylene), can also obviously improve the reaction stability of the catalyst, and obtains better technical effect.

Drawings

Fig. 1 is an XRD spectrum and an SEM photograph of the slurry after crystallization of gel I prepared [ example 1 ];

fig. 2 is an XRD spectrum and an SEM photograph of the slurry after crystallization of the prepared gel I [ example 2 ];

FIG. 3 is an XRD spectrum and SEM photograph of the slurry after crystallization of the prepared gel I [ example 3 ];

figure 4 is an XRD spectrum of the SAPO composite molecular sieve prepared [ example 4 ];

figure 5 is an SEM photograph of SAPO composite molecular sieves prepared [ example 4 ];

figure 6 is an SEM photograph of SAPO composite molecular sieves prepared [ example 8 ];

fig. 7 is an XRD spectrum and SEM photograph of the SAPO composite molecular sieve prepared in comparative example 1;

fig. 8 is an XRD spectrum and SEM photograph of the SAPO composite molecular sieve prepared in comparative example 2.

Detailed Description

As one embodiment of the present invention, it should be noted that the scope of the present invention is not limited by these specific embodiments, but is defined by the claims.

In the present invention, the molecular sieve (referred to as a single crystal) has a crystal morphology of a plate-like structure, particularly a primary crystal morphology of a plate-like structure, when observed with a Scanning Electron Microscope (SEM). Here, the crystal morphology refers to an external shape that a single molecular sieve crystal exhibits in an observation field of the scanning electron microscope, and the grain size refers to a grain size of a crystal grain of the single crystal. In the present invention, the length of the size of the molecular sieve crystal grains of the plate-like structure is defined as the longest side of the crystal, i.e., the a-axis direction of the molecular sieve crystal, the width is defined as the next longest side of the crystal, i.e., the b-axis direction of the molecular sieve crystal, and the thickness is defined as the shortest side of the crystal, i.e., the c-axis direction of the molecular sieve crystal.

In the invention, XRD data is measured by adopting a German Bruker AXS D8 advanced X-ray diffractometer and is used for representing the crystal structure, the relative crystallinity and the calculation of the content of the molecular sieve; SEM pictures were obtained from a field emission scanning electron microscope, FEI Quanta200F, the netherlands, and used to characterize the morphology of the molecular sieves.

In the invention, the solid content refers to the mass fraction of the dried material in the slurry. Wherein the drying temperature is generally 80-120 ℃.

The present invention is further illustrated by the following specific examples, which are only exemplary and do not limit the scope of the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention, and that such changes and modifications may be made without departing from the spirit and scope of the invention.

[ example 1 ]

Preparation of SAPO-18 slurry

With silica sol (30% by weight SiO)₂) Pseudo-boehmite (70 wt% Al)₂O₃) And phosphoric acid (85 wt% H)₃PO₄) Respectively a silicon source, an aluminum source and a phosphorus source, and a mixture of tetraethylammonium hydroxide and N, N-diisoethylpropylamine is taken as a template agent according to SiO₂：Al₂O₃：P₂O₅：R：H₂O ═ 0.3: 1.0: 0.9: 2.0: 45 to obtain a mixture gel I, wherein the proportion of tetraethylammonium hydroxide and N, N-diisoethylpropylamine is 2: 3, crystallizing the mixture gel I at 190 ℃ for 24 hours. And after crystallization is finished, cooling the crystallized product to obtain the molecular sieve slurry. And (3) taking a part of the slurry, directly drying the part of the slurry for calculating the solid content and the content of the molecular sieve in the solid product, and drying the other part of the slurry for 6 hours at 100 ℃ after filtering and washing to obtain a sample for characterization, wherein the sample is marked as A.

The solid content of the molecular sieve was calculated to be 42 wt% based on the dried sample weight.

The XRD spectrum and SEM photograph are shown in figure 1, and the result shows that the synthesized molecular sieve has the characteristic diffraction peak of the SAPO-18 molecular sieve, wherein the content of the SAPO-18 molecular sieve is 90 wt%. SEM photos show that the grain size of the prepared SAPO-18 molecular sieve is 0.2-0.5 micron crystal.

[ example 2 ]

Preparation of SAPO-18 slurry

As in example 1, except that the mixture gel I was crystallized at 170 ℃ for 5 hours. And after crystallization is finished, cooling the crystallized product to obtain the molecular sieve slurry. And taking part of the slurry, directly drying the part of the slurry for calculating the solid content and the content of the molecular sieve in the solid product, and filtering and washing the other part of the slurry, and drying the other part of the slurry for 6 hours at 100 ℃ to obtain a sample for characterization, wherein the sample is marked as B.

And calculating the solid content of the molecular sieve to be 40 wt% according to the weight of the dried sample.

The XRD pattern and SEM photograph are shown in FIG. 2, and the results show that the synthesized sample has the characteristic peak of SAPO-18 molecular sieve, wherein the content of SAPO-18 molecular sieve is about 15 wt%. SEM photos show that the grain size of the prepared SAPO-18 molecular sieve is 0.1-0.3 micron crystal.

[ example 3 ]

Preparation of SAPO-34 slurry

With silica sol (30% by weight SiO)₂) Pseudo-boehmite (70 wt% Al)₂O₃) And phosphoric acid (85 wt% H)₃PO₄) Respectively serving as a silicon source, an aluminum source and a phosphorus source, and tetraethylammonium hydroxide and triethylamine serving as template agents, wherein the proportion of the tetraethylammonium hydroxide to the triethylamine is 1: 2, according to SiO₂：Al₂O₃：P₂O₅：R：H₂O ═ 0.4: 1.0: 0.8: 4.0: 60 to obtain a mixture gel I, and crystallizing the mixture gel I at 195 ℃ for 10 hours. And after crystallization is finished, cooling the crystallized product to obtain the molecular sieve slurry. Taking part of the slurry and drying part of the slurry directly for calculationSolid content and molecular sieve content in the solid product, and the other part was filtered and washed, and then dried at 100 ℃ for 6 hours to obtain a sample for characterization, which was designated as C.

According to the weight of the dried sample, the solid content of the molecular sieve is calculated to be 35 wt%.

The XRD pattern and SEM photograph are shown in FIG. 3, and the result shows that the synthesized molecular sieve has the characteristic diffraction peak of SAPO-34 molecular sieve, wherein the content of SAPO-34 is 35 wt%. SEM photos show that the grain size of the prepared SAPO-34 molecular sieve is 0.1-0.3 micron crystal.

[ example 4 ]

Preparation of SAPO composite molecular sieve

With silica sol (30% by weight SiO)₂) Pseudo-boehmite (70 wt% Al)₂O₃) And phosphoric acid (85 wt% H)₃PO₄) Respectively as Si, Al and P sources, triethylamine NEt₃And tetraethylammonium hydroxide TEAOH as a template agent according to SiO₂：Al₂O₃：P₂O₅：NEt₃：TEAOH：H₂O ═ 0.6: 1.0: 0.6: 3.0: 1.0: 50, adding the molecular sieve slurry prepared by the method (example 1), and continuously stirring for more than 2 hours, wherein the adding amount of the SAPO-18 molecular sieve slurry accounts for 10 wt% in terms of solid content. The mixture was crystallized at 200 ℃ for 20 hours. And after crystallization is finished, cooling, filtering, washing and drying the crystallized product, and roasting at 550 ℃ for 5 hours to obtain the SAPO composite molecular sieve marked as D.

The XRD spectrum of D is shown in figure 4, and it can be seen from figure 4 that the synthesized molecular sieve has the characteristic diffraction peak of the SAPO-34/SAPO-18 molecular sieve, which indicates that the synthesized product is the SAPO composite molecular sieve, and the XRD quantitative method can be used to know that the content of the SAPO-18 molecular sieve in the composite molecular sieve is 8 wt% and the content of the SAPO-34 molecular sieve is 92 wt%.

D, an SEM photograph is shown in figure 5, wherein the molecular sieve is in a plate shape, the length of the molecular sieve is 0.5-1.0 micron, the width of the molecular sieve is 0.5-1.0 micron, and the thickness of the molecular sieve is 0.1-0.2 micron.

According to the results of XRD (X-ray diffraction) patterns and SEM (scanning electron microscope) photographs, the prepared SAPO composite molecular sieve with the plate-shaped structural morphology is proved to be enough.

[ example 5 ]

Preparation of SAPO composite molecular sieve

Similarly [ example 4 ], except that the amount of SAPO-18 molecular sieve slurry added was 20 wt% based on the solid content, the resulting product was designated as E.

The XRD spectrum of E is similar to that of FIG. 4, and the content of the molecular sieve with SAPO-18 structure in the composite molecular sieve is 12 wt% and the content of the molecular sieve SAPO-34 in the composite molecular sieve is 88 wt% by using the XRD quantitative method.

The SEM photograph of E is similar to that of FIG. 5, the molecular sieve has a plate-like shape, a length of 0.5-1.0 micron, a width of 0.5-1.0 micron and a thickness of 0.1-0.2 micron.

According to the results of an XRD (X-ray diffraction) spectrum and an SEM (scanning electron microscope) picture, the prepared SAPO composite molecular sieve with the plate-shaped structural morphology is proved to be enough.

[ example 6 ]

Preparation of SAPO composite molecular sieve

Likewise [ example 4 ], but SiO of the gel mixture₂：Al₂O₃The product obtained was noted F, 0.2.

The XRD spectrum of F is similar to that of FIG. 4, and the content of SAPO-18 molecular sieve in the composite molecular sieve is 12 wt% and the content of SAPO-34 molecular sieve is 88 wt% by using the XRD quantitative method.

The SEM photograph of F is similar to that of FIG. 5, the molecular sieve has a plate-like shape, a length of 0.5-1.0 micron, a width of 0.5-1.0 micron and a thickness of 0.1-0.2 micron.

According to the results of an XRD (X-ray diffraction) spectrum and an SEM (scanning electron microscope) picture, the prepared SAPO composite molecular sieve with the plate-shaped structural morphology is proved to be enough.

[ example 7 ]

Preparation of SAPO composite molecular sieve

The same as in example 4, except that the SAPO-18 molecular sieve slurry used was synthesized as in example 2, and the resulting product was noted G.

The XRD spectrum of G is similar to that of FIG. 4, and it can be known that the content of SAPO-18 molecular sieve in the composite molecular sieve is 5 wt%, and the content of SAPO-34 molecular sieve is 95 wt% by using XRD quantitative method.

The SEM photograph of G is similar to that of FIG. 5, the molecular sieve has a plate-like shape, a length of 0.5-1.0 micron, a width of 0.5-1.0 micron and a thickness of 0.1-0.2 micron.

According to the results of XRD (X-ray diffraction) patterns and SEM (scanning electron microscope) photographs, the prepared SAPO composite molecular sieve with the plate-shaped structural morphology is proved to be enough.

[ example 8 ]

Preparation of SAPO composite molecular sieve

With silica sol (30% by weight SiO)₂) Pseudo-boehmite (70 wt% Al)₂O₃) And phosphoric acid (85 wt% H)₃PO₄) Respectively a silicon source, an aluminum source and a phosphorus source, and a mixture of tetraethylammonium hydroxide and N, N-diisoethylpropylamine is taken as a template agent according to SiO₂：Al₂O₃：P₂O₅：R：H₂O ═ 0.3: 1.0: 0.9: 2.0: 45, wherein the ratio of tetraethylammonium hydroxide to N, N-diisoethylpropylamine is 2: and 3, adding the molecular sieve slurry prepared by the method in the embodiment 3, and continuously stirring for more than 2 hours, wherein the adding amount of the SAPO-34 molecular sieve slurry accounts for 10 wt% of the solid content. The mixture was crystallized at 200 ℃ for 24 hours. And after crystallization is finished, cooling, filtering, washing and drying the crystallized product, and roasting at 550 ℃ for 5 hours to obtain the SAPO composite molecular sieve, wherein the SAPO composite molecular sieve is marked as H.

The XRD spectrogram of H proves that the synthesized molecular sieve has the characteristic diffraction peaks of the SAPO-34 and SAPO-18 molecular sieves, which indicates that the synthesized product is the SAPO composite molecular sieve, and the XRD quantitative method can be used for knowing that the composite molecular sieve contains 92 wt% of the SAPO-18 molecular sieve and 8 wt% of the SAPO-34 molecular sieve.

The SEM photograph of H is shown in FIG. 6, the molecular sieve is plate-shaped, the length is 0.3-0.8 micrometer, the width is 0.3-0.8 micrometer, and the thickness is 0.1-0.2 micrometer.

According to the results of XRD (X-ray diffraction) patterns and SEM (scanning electron microscope) photographs, the prepared SAPO composite molecular sieve with the plate-shaped structural morphology is proved to be enough.

Comparative example 1

As in example 4, except that the slurry of molecular sieve prepared as in example 1 was not added during the synthesis, the resulting product was noted as I.

The XRD spectrogram and SEM photograph of the compound I are shown in figure 7, and the synthesized molecular sieve has the characteristic diffraction peak of the SAPO-34 molecular sieve; the crystal of the molecular sieve is cubic, the grain size is 2-3 microns, and the surface is smooth.

According to the results of XRD spectrogram and SEM photograph, the prepared molecular sieve is proved to be a cubic SAPO-34 molecular sieve.

Comparative example 2

As in example 4 except that the centrifuged and dried solid seed powder prepared in example 1 was added during the synthesis in place of the molecular sieve slurry, the product was noted as J.

The XRD spectrogram and SEM photograph of J are shown in FIG. 8, and it can be seen from FIG. 8 that the synthesized molecular sieve has the characteristic diffraction peak of the SAPO-34/SAPO-18 molecular sieve, which indicates that the synthesized product is the SAPO composite molecular sieve, and the XRD quantitative method can be used to know that the content of the SAPO-18 molecular sieve in the composite molecular sieve is 6 wt% and the content of the SAPO-34 molecular sieve is 94 wt%. The molecular sieve has a cubic and plate-shaped appearance and an irregular appearance of lamellar stacking, and the grain size distribution is wide and is 0.3-3.0 microns.

According to the results of XRD spectrogram and SEM photograph, the prepared SAPO composite molecular sieve is proved.

[ example 9 ]

The molecular sieves obtained in examples 4 to 8 and comparative examples 1 to 2 were tabletted to prepare catalysts for the reaction of producing olefins from methanol. A fixed bed catalytic reaction device is adopted, a reactor is a stainless steel tube, and the used process conditions are considered as follows: the catalyst loading is 2.0g, the reaction temperature is 460 ℃, and the weight space velocity is 3h^-1The pressure was 0.1MPa, and the evaluation results are shown in Table 1, wherein the lifetime of the catalyst is the time corresponding to the time at which the diene selectivity reached the maximum, and the gas-phase product analysis results in Table 1 are data on the time at which the lifetime of the catalyst reached. It can be seen that the composite molecular sieve of the invention is used in MTO reaction, can obviously improve the yield of diene, and the catalyst has better stability. In the present invention, the yield of each product is as followsAnd (4) measuring the mass.

TABLE 1