Synthesis method of molecular sieve
阅读说明：本技术 一种分子筛的合成方法 (Synthesis method of molecular sieve ) 是由 韩蕾 王鹏 达志坚 宋海涛 林伟 严加松 于 2020-06-30 设计创作，主要内容包括：本发明属于分子筛合成技术领域,涉及一种分子筛的合成方法,该方法包括如下步骤：(1)第一β分子筛合成液在温度为50-250℃下反应2-36小时进行第一晶化,第一晶化结束后,过滤、洗涤、干燥、焙烧；(2)步骤(1)产物与水混合；(3)ZSM-5分子筛与步骤(2)产物混合,搅拌,形成浆液,过滤；(4)步骤(3)产物与第二β分子筛合成液混合,进行第二晶化。该方法可以合成核壳分子筛。(The invention belongs to the technical field of molecular sieve synthesis, and relates to a synthesis method of a molecular sieve, which comprises the following steps: (1) reacting the first beta molecular sieve synthetic solution at 50-250 ℃ for 2-36 hours to carry out first crystallization, and after the first crystallization is finished, filtering, washing, drying and roasting; (2) mixing the product of the step (1) with water; (3) mixing a ZSM-5 molecular sieve with the product obtained in the step (2), stirring to form slurry, and filtering; (4) and (4) mixing the product obtained in the step (3) with a second beta molecular sieve synthetic solution, and carrying out second crystallization. The method can synthesize the core-shell molecular sieve.)
1. A method for synthesizing a core-shell molecular sieve comprises the following steps:
(1) reacting the first beta molecular sieve synthetic solution at the temperature of 50-250 ℃ for 2-36 hours to perform first crystallization, and filtering, washing, drying and roasting after the first crystallization is finished to obtain a first solid;
(2) mixing the first solid obtained in the step (1) with water to obtain first slurry;
(3) mixing a ZSM-5 molecular sieve with the first slurry obtained in the step (2), stirring to form second slurry, and filtering to obtain a second solid;
(4) and (4) mixing the second solid obtained in the step (3) with a second beta molecular sieve synthetic solution, and carrying out second crystallization.
2. The synthesis method according to claim 1, wherein the first crystallization of step (1): the crystallization temperature is 70-200 ℃, and the crystallization time is 5-30 hours.
3. The synthesis process according to claim 1 or 2, wherein the first solid obtained in step (1) is subjected to XRD analysis and has a peak at 22.4 ° 2 θ and no peak at 21.2 ° 2 θ.
4. The method as claimed in claim 1, wherein in the step (2), the solid content of the slurry formed by mixing the first solid obtained in the step (1) and water is 2-50 wt%.
5. The process of claim 1 or 3, wherein in step (3) the ZSM-5 molecular sieve is mixed with the first slurry obtained in step (2) in a weight ratio of dry ZSM-5 molecular sieve to dry first slurry obtained in step (2) of 1-10: 1.
6. The process of claim 1 or 5, wherein in step (3), the weight ratio of ZSM-5 molecular sieve dry basis to the first slurry obtained in step (2) is 0.01-0.5: 1.
7. The method of claim 1 or 5, wherein in step (3), the stirring is high shear stirring, and in one embodiment, the high shear stirring is performed by: mixing a ZSM-5 molecular sieve with the product obtained in the step (2) to form a mixture, and shearing the mixture at the temperature of between 30 and 80 ℃ and at the shearing speed of between 6000 and 20000r/min for 0.1 to 2 hours.
8. The synthesis method of claim 1, wherein the ZSM-5 molecular sieve of step (3) has a Si/Al molar ratio of SiO2/Al2O3In the amount of 10- ∞, for example, 30 to 300.
9. The process of claim 1, wherein in step (4), the weight ratio of the second solid of step (3) to the second beta molecular sieve synthesis solution on a dry basis is 0.1-0.5:1, such as 0.15-0.4: 1.
10. the molecular sieve synthesis process of claim 1 or 8, wherein the second crystallization in step (4): the crystallization temperature is 50-300 ℃, and the crystallization time is 0.5-480 hours.
11. The method for synthesizing the molecular sieve according to claim 1 or 10, wherein in the step (4), the second solid in the step (3) is added into the beta molecular sieve synthesis solution, and then is crystallized at 100-250 ℃ for 20-350 hours; the crystallization temperature of the second crystallization is preferably 100 to 200 c, for example, 120 to 180 c, and the crystallization time of the second crystallization is preferably 36 to 120 hours.
12. The synthesis method according to claim 1, wherein the first beta molecular sieve synthesis solution and the second beta molecular sieve synthesis solution each contain a silicon source, an aluminum source, a template agent and water, and wherein the molar ratios of the silicon source, the aluminum source, the template agent and the water in the first beta molecular sieve synthesis solution and the second beta molecular sieve synthesis solution are each set to be equal to each otherThe method comprises the following steps: R/SiO20.1-10, e.g. 0.1-3:1 or 0.2-2.2:1, H2O/SiO22-150 e.g. 10-120:1, SiO2/Al2O310-800 or 20-800, Na2O/SiO20-2, for example 0.01-1.7 or 0.05-1.3:1 or 0.1-1.1:1, wherein R represents a templating agent.
13. The synthesis method according to claim 1 or 12, wherein the preparation method of each of the first beta molecular sieve synthesis solution of step (1) and the second beta molecular sieve synthesis solution of step (4) comprises: and mixing a silicon source, an aluminum source, a template agent and water to obtain the beta molecular sieve synthetic solution.
14. The method of synthesis of claim 12 or 13, wherein the source of aluminum is selected from at least one of aluminum sulfate, aluminum isopropoxide, aluminum nitrate, aluminum sol, sodium metaaluminate or gamma-alumina; the template agent is selected from at least one of tetraethylammonium fluoride, tetraethylammonium hydroxide, tetraethylammonium bromide, tetraethylammonium chloride, tetraethylammonium iodide, polyvinyl alcohol, triethylamine, isopropylamine, di-n-propylamine, hexadecyltrimethylammonium bromide, isopropanol, triethanolamine and sodium carboxymethylcellulose.
15. The synthesis method according to claim 12, 13 or 14, wherein the silicon source used in the first beta molecular sieve synthesis solution in step (1) is at least one selected from ethyl orthosilicate, water glass and silica sol; and (4) selecting at least one silicon source from tetraethoxysilane, water glass, coarse-pore silica gel, silica sol, white carbon black and activated clay in the second beta molecular sieve synthetic solution.
16. A core shell molecular sieve obtainable by a process for synthesizing a core shell molecular sieve according to any one of claims 1 to 15.
17. The core shell molecular sieve of claim 16, wherein the shell molecular sieve has a silica to alumina molar ratio in SiO2/Al2O3In the range of 10-500, for example 25-200。
18. The core shell molecular sieve of claim 16, wherein the core shell molecular sieve is a ZSM-5/β core shell molecular sieve having an XRD pattern with a ratio of peak height at 22.4 ° 2 θ to peak height at 23.1 ° 2 θ of 0.1 to 10:1 or 0.1 to 0.35: 1.
19. the core shell molecular sieve of claim 16, wherein the core-shell molecular sieve has a ratio of core phase to shell phase of 0.2-20:1, e.g., 1-15:1, and the shell molecular sieve of the core shell molecular sieve has a thickness of 10nm-2000 nm.
20. Core shell molecular sieve according to claim 16, wherein the core shell molecular sieve shell coverage is 50-100%, such as 80-100%.
21. Use of the core shell molecular sieve of any of claims 16-20 in catalytic cracking of hydrocarbon oils.
Technical Field
The invention belongs to the technical field of molecular sieve synthesis, and relates to a synthesis method of a core-shell molecular sieve suitable for hydrocarbon cracking.
Background
Zeolite molecular sieves are microporous crystalline materials with framework structures, have pore channel structures with specific sizes and shapes, large specific surfaces and strong adjustable acid properties, and are widely applied to petroleum refining and processing processes, such as catalytic reactions of catalytic cracking, alkane isomerization, catalytic reforming, toluene disproportionation and the like.
Beta molecular sieves having the BEA topology and ZSM-5 molecular sieves having the MFI topology are two molecular sieves that are widely used in industry. Beta zeolite is the only macroporous three-dimensional structure high-silica zeolite with a crossed twelve-membered ring channel system discovered so far, and has both acid catalytic property and structure selectivity due to structural particularity. The catalyst has the characteristics of good thermal and hydrothermal stability, moderate acidity and acid stability and hydrophobicity, and shows that the hydrocarbon reaction is not easy to coke and the service life is long in catalytic application. ZSM-5 belongs to the orthorhombic system and has unit cell parameter ofThe number of Al atoms in the unit cell can vary from 0 to 27, the silicon to aluminum ratio can vary over a wide range; the ZSM-5 skeleton contains two 10-membered ring channel systems which are crossed with each other, wherein the channel is S-shaped and bent, and the aperture isThe pore canal is in a linear shape and has a pore diameter of
In recent years, the combination of two molecular sieves has been studied for use in catalytic reaction processes. One way is to form the two molecular sieves into a core shell molecular sieve. However, the prior art does not disclose how to combine two molecular sieves to form a core-shell molecular sieve with better catalytic cracking effect. CN101885493A discloses a method for synthesizing a ZSM-5/beta core-shell zeolite molecular sieve, which comprises the steps of adopting a ZSM-5 nuclear phase molecular sieve as a seed crystal, performing surface pretreatment and adsorbing beta nanocrystalline, and then using at least one of cheap and easily obtained water glass, silica sol, sodium silicate, white carbon black or activated clay as a silicon source to prepare the ZSM-5/beta core-shell zeolite molecular sieve with high shell coverage. The disclosed synthesis process uses a surfactant when adsorbing the beta molecular sieve nanocrystals, increasing the synthesis cost. The disclosed core-shell molecular sieve has poor effect on preparing olefin by catalytic cracking.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for synthesizing a core-shell molecular sieve, which synthesizes the core-shell molecular sieve with higher shell coverage without using a surfactant.
The invention provides a synthesis method of a core-shell molecular sieve, which comprises the following steps:
(1) reacting the first beta molecular sieve synthetic solution at 50-250 ℃ for 2-36 hours to carry out first crystallization, and after the first crystallization is finished, filtering, washing, drying and roasting to obtain a solid product called as a first solid;
(2) mixing the first solid obtained in the step (1) with water to form slurry, namely first slurry;
(3) mixing a ZSM-5 molecular sieve (raw material) with the product obtained in the step (2), namely the first slurry, stirring to form a second slurry, and filtering to obtain a solid product called as a second solid;
(4) and (4) mixing the second solid obtained in the step (3) with a second beta molecular sieve synthetic solution, and carrying out second crystallization.
The invention also provides a molecular sieve material obtained by the synthesis method of the core-shell molecular sieve.
The synthesis method of the core-shell molecular sieve can obtain the ZSM-5/beta core-shell molecular sieve. No surfactant is used in the synthesis process. The obtained core-shell molecular sieve product has high shell coverage which can reach more than 50%. The core-shell molecular sieve synthesized by the method for synthesizing the core-shell molecular sieve can have a unique pore channel structure and acid distribution. The core-shell molecular sieve obtained by the synthesis method of the core-shell molecular sieve is used for catalytic cracking reaction of hydrocarbon oil, and has higher selectivity of low-carbon olefin, especially obviously higher yield of ethylene and/or propylene.
The core-shell molecular sieve provided by the invention can be used for catalytic cracking of hydrocarbon oil. The heavy oil catalytic cracking conversion method comprises a step of contacting and reacting hydrocarbon oil with a catalyst containing the core-shell molecular sieve, wherein the reaction conditions can adopt the existing catalytic cracking reaction conditions, for example, the contact reaction conditions comprise: the reaction temperature is 450-700 ℃, such as 500-650 ℃ or 550-630 ℃, the reaction time is 0.5-10s, such as 1-8 or 2-5s, and the catalyst-oil ratio is 3-40:1, such as 5-30:1 or 5-20:1 by weight. Steam is generally introduced during the reaction in a steam-to-oil ratio (weight ratio of steam to oil), for example from 0.05 to 10:1 or from 0.1 to 5:1 or from 0.15 to 1:1 or from 0.2 to 0.5: 1.
Drawings
FIG. 1 is an XRD pattern of ZSM-5/beta core-shell molecular sieve prepared in example 1 of the present invention, and it can be seen that characteristic peaks of ZSM-5 and beta exist simultaneously in the XRD pattern
Detailed Description
The dry basis of the invention is as follows: the solid product obtained after calcining the material in air at 850 ℃ for 1 hour.
According to the synthesis method of the core-shell molecular sieve provided by the invention, in the step (1), the first beta molecular sieve synthetic liquid is subjected to crystallization reaction, and the process can be carried out under stirring or standing. Step (1), the first crystallization: the crystallization temperature is 70-200 ℃, and the crystallization time is 5-30 h. Preferably, the first crystallization: the crystallization temperature is 75-200 ℃, and the crystallization time is 5-28 h; more preferably, the first crystallization: the crystallization temperature is 70-180 deg.C, the crystallization time is 6-28 hr, such as 10-28 hr, for example, the crystallization temperature is 70-150 deg.C, the crystallization time is 6-28 hr or the crystallization temperature is 80-150 deg.C, and the crystallization time is 6-18 hr.
According to the method for synthesizing the core-shell molecular sieve, the first beta molecular sieve synthetic solution contains a silicon source, an aluminum source, a template agent (represented by R) and water. In one embodiment, the method for preparing the first beta molecular sieve synthesis solution in step (1) comprises: and (3) preferably deionizing and mixing a silicon source, an aluminum source, a template agent and water to obtain the beta molecular sieve synthetic solution. Wherein the molar ratio of the silicon source to the aluminum source to the template to the water is as follows: R/SiO20.1-10, e.g. 0.1-3:1 or 0.2-2.2:1, H2O/SiO22-150 e.g. 10-120:1, SiO2/Al2O310-800 e.g. 20-800, Na2O/SiO20-2, for example 0.01-1.7 or 0.05-1.3:1 or 0.1-1.1: 1.
According to the method for synthesizing the core-shell molecular sieve provided by the invention, in the step (1), preferably, the silicon source used in the first beta molecular sieve synthesis solution is at least one selected from a liquid silicon source such as tetraethoxysilane, water glass and silica sol, and the use of the silicon source can have a better effect. The aluminum source may be selected from at least one of aluminum sulfate, aluminum isopropoxide, aluminum nitrate, aluminum sol, sodium metaaluminate, or gamma-alumina. The template agent (R) is, for example, one or more of tetraethylammonium fluoride, tetraethylammonium hydroxide, tetraethylammonium bromide, tetraethylammonium chloride, tetraethylammonium iodide, polyvinyl alcohol, triethylamine, isopropylamine, di-n-propylamine, hexadecyltrimethylammonium bromide, isopropanol, triethanolamine, and sodium carboxymethylcellulose.
According to the synthesis method of the core-shell molecular sieve provided by the invention, in the step (1), the washing can be performed by washing with water, for example, deionized water and the first crystallized product can be mixed according to the weight ratio of the first crystallized product to water of 1:5-1:20 on a dry basis, and the washing can be performed one or more times until the pH value of the water after washing is less than 9, for example, 8-9. The drying mode has no special requirements, and can be drying, flash drying and air flow drying; the conditions for drying are, for example: the temperature for drying is 50 ℃ to 150 ℃ and the drying time is not limited as long as the sample is dried, and may be, for example, 0.5 hour to 4 hours. The roasting condition is as follows: the calcination temperature may be at least 300 deg.C, for example, 300 deg.C-700 deg.C, and the calcination time may be, for example, 0.5 hour-8 hours.
According to the synthesis method of the core-shell molecular sieve, the first solid obtained in the step (1) is subjected to XRD analysis, and the XRD pattern of the first solid has a spectrum peak at the position of 22.4 degrees 2 theta and has no spectrum peak at the position of 21.2 degrees 2 theta. The ratio of the intensity of the peak at 22.4 ° 2 θ to the intensity of the peak at 21.2 ° 2 θ is infinite. The crystallization reaction in the step (1) enables the crystallization state of the obtained synthetic liquid after the crystallization reaction to be a state that crystal grains are not appeared yet, and the synthetic liquid is about to enter a crystal nucleus rapid growth stage near the end of a crystallization induction period. The peak at 22.4 ° means a peak in the range of 22.4 ° ± 0.1 ° 2 θ, and the peak at 21.2 ° 2 θ means a peak in the range of 21.2 ° ± 0.1 ° 2 θ.
According to the synthesis method of the core-shell molecular sieve provided by the invention, in the step (2), the product obtained in the step (1) is mixed with water such as deionized water to form slurry, and the solid content of the slurry is preferably 2-50 wt%, such as 5-50 wt% or 2-30 wt%.
According to the synthesis method of the core-shell molecular sieve, provided by the invention, in the step (3), the ZSM-5 molecular sieve (raw material) and the product obtained in the step (2), namely the first slurry are mixed, and the dry weight ratio of the ZSM-5 molecular sieve (raw material) to the product obtained in the step (2) is 1-10:1, such as 2-8: 1. In one embodiment, the weight ratio of ZSM-5 molecular sieve (feedstock) to the slurry obtained in step (2) (first slurry) is in the range of from 0.01 to 0.5:1, e.g., or from 0.03 to 0.3: 1. The stirring is preferably intensive stirring such as high shear stirring, and in one embodiment, the high shear stirring is performed by: the mixture obtained by mixing the ZSM-5 molecular sieve (raw material) and the product obtained in the step (2) is sheared for 0.1h-2h at the temperature of 30-80 ℃ under a high-speed shearing machine, and the shearing rotating speed is 6000r/min-20000r/min for example.
According to the synthesis method of the core-shell molecular sieve, provided by the invention, the silica-alumina molar ratio of the ZSM-5 molecular sieve (raw material) in the step (3) is SiO2/Al2O3Calculated as 10- ∞; such as the ZSM-5 molecular sieve(raw material) Si/Al molar ratio in terms of SiO2/Al2O3It may be 20-infinity, or 50-infinity, or 30-300, or 30-200, or 20-80, or 25-70, or 30-60.
According to the synthesis method of the core-shell molecular sieve provided by the invention, in the step (4), the weight ratio of the second solid obtained in the step (3) to the second beta molecular sieve synthesis solution on a dry basis is 0.1-0.5, such as 0.15-0.4:1 or 0.1-0.25: 1.
according to the synthesis method of the core-shell molecular sieve provided by the invention, in the step (4), the second solid product obtained in the step (3) is mixed with the second beta molecular sieve synthetic fluid, and the weight ratio of the second beta molecular sieve synthetic fluid to the ZSM-5 molecular sieve (raw material) on a dry basis is preferably 2-10:1, for example 4-10: 1.
The synthesis method of the core-shell molecular sieve provided by the invention comprises the following steps of (1) carrying out second crystallization: the crystallization temperature is 50-300 ℃, and the crystallization time is 0.5-480 h, preferably 10-400 h, for example 20-200 h. In one embodiment, in the step (4), the product of the step (3) is added into the beta molecular sieve synthesis solution, and then crystallized for 20h to 350h at 100 ℃ to 250 ℃, preferably at 100 ℃ to 200 ℃, for example, 120 ℃ to 180 ℃, and for 36h to 120 h.
According to the method for synthesizing the core-shell molecular sieve, the second beta molecular sieve synthetic solution contains a silicon source, an aluminum source, a template agent (represented by R) and water, wherein the molar ratio of the silicon source to the aluminum source to the template agent to the water is as follows: R/SiO20.1-10, e.g. 0.1-3:1 or 0.2-2.2:1, H2O/SiO22-150 e.g. 10-120:1, SiO2/Al2O310-800 or 20-800, Na2O/SiO20-2, for example 0.01-1.7 or 0.05-1.3:1 or 0.1-1.1: 1. The first beta molecular sieve synthetic fluid and the second beta molecular sieve synthetic fluid can have the same or different compositions.
According to the synthesis method of the core-shell molecular sieve provided by the invention, the preparation method of the second beta molecular sieve synthetic fluid in the step (4) comprises the following steps: and (3) preferably deionizing and mixing a silicon source, an aluminum source, a template agent and water to obtain the beta molecular sieve synthetic solution.
According to the synthesis method of the core-shell molecular sieve provided by the invention, in the step (4), the silicon source used in the second beta molecular sieve synthetic solution can be at least one selected from ethyl orthosilicate, water glass, coarse silica gel, silica sol, white carbon black or activated clay; the aluminum source may be selected from at least one of aluminum sulfate, aluminum isopropoxide, aluminum nitrate, aluminum sol, sodium metaaluminate, or gamma-alumina. The template agent (R) may be one or more of tetraethylammonium fluoride, tetraethylammonium hydroxide, tetraethylammonium bromide, tetraethylammonium chloride, tetraethylammonium iodide, polyvinyl alcohol, triethylamine, isopropylamine, di-n-propylamine, hexadecyltrimethylammonium bromide, isopropanol, triethanolamine, and sodium carboxymethylcellulose.
The synthesis method of the core-shell molecular sieve provided by the invention further comprises the step of recovering a core-shell molecular sieve product. The recovering typically comprises subjecting the second crystallized product to one or more of filtering, washing, drying, and calcining, for example, the second crystallized product is sequentially subjected to filtering, washing, drying, and calcining. Methods of filtration, washing, drying, calcination are well known to those skilled in the art and reference may be made to the prior art. In one embodiment, the washing may be water washing, for example, deionized water and crystallized product may be washed according to a weight ratio of core-shell molecular sieve to water of 1:5 to 1:20, and the washing may be performed one or more times until the pH of the water after washing is 9 or less, for example, 8 to 9. The drying conditions are, for example: the drying temperature may be from room temperature to 200 deg.C, such as from 50 deg.C to 150 deg.C, the drying temperature may be from 80 deg.C to 120 deg.C, and the drying time may be, for example, from 0.5h to 24 h; the drying may be pneumatic drying, flash drying, oven drying or air drying. The roasting condition is as follows: the calcination temperature is at least 300 ℃, for example, 300 ℃ and 700 ℃, and the calcination time is 0.5 to 8 hours; preferably, the roasting temperature is 300-650 ℃, and the roasting time is 1-6 h.
The core-shell molecular sieve provided by the invention is characterized in that the silica-alumina molar ratio of the shell molecular sieve is SiO2/Al2O3In terms of silicon to aluminium ratio, from 10 to 500, preferably from 10 to 300, for example from 30 to 200 or from 25 to 200.
The core-shell molecular sieve according to the present invention, wherein the XRD spectrum of the core-shell molecular sieve is such that the ratio of the peak height of the peak at 22.4 ° (D1) to the peak height of the peak at 23.1 ° (D2) at 2 θ is, for example, 0.1 to 10:1, such as 0.1 to 8:1 or 0.8 to 8:1 or 0.1 to 5:1 or 0.1 to 0.35: 1. the peak at 22.4 ° is a peak in the range of 22.4 ° ± 0.1 ° in the X-ray diffraction pattern, and the peak at 23.1 ° is a peak in the range of 23.1 ° ± 0.1 ° in the X-ray diffraction pattern.
The core-shell molecular sieve provided by the invention has the advantages that the ratio of the core phase to the shell layer of the core-shell molecular sieve is 0.2-20:1, such as 1-15:1, and the ratio of the core phase to the shell layer can be calculated by adopting the peak area of an X-ray diffraction spectrum.
The thickness of the shell layer molecular sieve of the core-shell molecular sieve is 10nm to 2000nm, for example, 50nm to 2000 nm.
The core-shell molecular sieve provided by the invention is characterized in that the silica-alumina molar ratio of the core-phase molecular sieve of the core-shell molecular sieve is SiO2/Al2O3In the amount of 10- ∞, for example 20- ∞ or 50- ∞ or 30-300 or 30-200 or 20-80 or 25-70 or 30-60.
The core-shell molecular sieve of the present invention, wherein the shell coverage of the core-shell molecular sieve is 50% to 100%, for example 80% to 100%.
According to the ZSM-5/beta core-shell molecular sieve provided by the invention, in one embodiment, the total specific surface area of the ZSM-5/beta core-shell molecular sieve (also called the specific surface area of the ZSM-5/beta core-shell molecular sieve) is more than 420m2G is, for example, 420m2/g-650m2The total specific surface area of the ZSM-5/beta core-shell molecular sieve is preferably more than 450m2G is, for example, 450m2/g-620m2(iv)/g or 480m2/g-600m2G or 490m2/g-580m2G or 500m2/g-560m2/g。
The ZSM-5/beta core-shell molecular sieve provided by the invention has the advantages that the proportion of the pore surface area to the total surface area (or the specific surface area of the mesopores to the total specific surface area) of the ZSM-5/beta core-shell molecular sieve is 10-40%, such as 12-35%. Wherein, the mesopores refer to pores with a pore diameter of 2nm to 50 nm.
The following examples further illustrate the invention but are not intended to limit the invention thereto.
Raw materials used in examples and comparative examples:
ZSM-5 molecular sieve, H type, silica alumina ratio (in SiO)2/Al2O3Mole ratio) of 30, crystallinity of 93.0%, factory: qilu division, petrochemical catalyst, Inc., China.
In the examples, the cutter used was an IKA T25 digital model, and the manufacturer was IKA instruments and equipment limited (IKA china).
In the examples and comparative examples, XRD analysis was performed using the following instruments and test conditions: the instrument comprises the following steps: empyrean. And (3) testing conditions are as follows: tube voltage 40kV, tube current 40mA, Cu target Ka radiation, 2 theta scanning range 5-35 degrees, scanning speed 2(°)/min. And (3) calculating the proportion of the nuclear phase and the shell layer by analyzing the spectrum peak through X-ray diffraction, and performing fitting calculation by using a fitting function pseudo-voigt through JADE software.
The thickness of the shell layer molecular sieve is measured by adopting a TEM method, the thickness of a shell layer at a certain position of one core-shell molecular sieve particle is randomly measured, 10 particles are measured, and the average value is taken.
The coverage of the molecular sieve is measured by adopting an SEM method, the proportion of the outer surface area of a shell layer of one nuclear phase particle to the outer surface area of the nuclear phase particle is calculated, the coverage of the particle is taken as the coverage, 10 particles are randomly measured, and the average value is taken.
And measuring the silicon-aluminum ratio of the shell layer molecular sieve by adopting a TEM-EDS method.
The mesopore surface area (mesopore specific surface area), the specific surface area, the pore volume (total pore volume) and the pore size distribution are measured by adopting a low-temperature nitrogen adsorption capacity method, an ASAP2420 adsorption instrument of American Micromeritics company is used, samples are respectively degassed for 0.5h and 6h at 100 ℃ and 300 ℃, an N2 adsorption and desorption test is carried out at 77.4K, the adsorption capacity and the desorption capacity of the samples to nitrogen under different specific pressures are tested, and N is obtained2Adsorption-desorption isotherm curve. The BET specific surface area (total specific surface area) was calculated using the BET formula, and the micropore area was calculated using t-plot.
Example 1
(1) 2.0g of aluminum isopropoxide was dissolved in 30.0g of deionized water, 1.30g of NaOH pellets were added, and then 40.0g of silica Sol (SiO) was added in sequence225.0 weight percent of sodium oxide, pH value of 10 and sodium oxide content of 0.10 weight percent, and 20.0g of tetraethylammonium hydroxide solution (the weight percentage of tetraethylammonium hydroxide in the tetraethylammonium hydroxide solution is 25 weight percent), stirring uniformly, transferring into a reaction kettle with a polytetrafluoroethylene lining for crystallization, crystallizing at 80 ℃ for 18 hours, filtering, washing, drying and roasting at 550 ℃ for 2 hours; the XRD spectrum of the obtained product has a peak at the 2 theta-22.4 degrees and has no peak at the 2 theta-21.2 degrees;
(2) uniformly mixing the product obtained in the step (1) with 70.0g of deionized water;
(3) adding 15.0g of ZSM-5 molecular sieve (calculated on a dry basis) into the slurry obtained in the step (2), shearing at a high speed for 1h under the condition of water bath at the temperature of 60 ℃, rotating at the speed of 15000r/min, and filtering to obtain a second solid;
(4) dissolving 1.0g sodium metaaluminate in 15.0g deionized water, adding 0.36g NaOH granules, and sequentially adding 10.0g coarse-pore silica gel (SiO)2Content 98.0 wt%) and 18g tetraethylammonium hydroxide solution (mass fraction of tetraethylammonium hydroxide in tetraethylammonium hydroxide solution is 25 wt%), stirring for 1h, adding the second solid obtained in step (3), and stirring for 30 min; transferring into a reaction kettle with a polytetrafluoroethylene lining for crystallization, crystallizing at 150 ℃ for 54h, filtering, washing, drying, and roasting at 550 ℃ for 2 h.
Example 2
(1) 2.0g of alumina sol (Al)2O3Is 25% by weight, the aluminium to chlorine molar ratio is 1.1; ) Dissolving in 5.0g deionized water, adding 0.3g NaOH granules, and sequentially adding 40mL water glass (SiO)2251g/L of concentration, 2.5 of modulus) and 12.5g of tetraethylammonium hydroxide solution (the weight percentage of tetraethylammonium hydroxide in the tetraethylammonium hydroxide solution is 25 percent), evenly stirred, transferred into a reaction kettle with a polytetrafluoroethylene lining for crystallization, crystallized for 6 hours at 150 ℃, filtered, washed, dried and roasted for 2 hours at 550 ℃; the XRD spectrum of the obtained product has a peak at the 2 theta-22.4 degrees and has no peak at the 2 theta-21.2 degrees;
(2) uniformly mixing the product obtained in the step (1) with 100.0g of deionized water;
(3) adding 15.0g of ZSM-5 molecular sieve into the slurry obtained in the step (2), shearing at a high speed of 80 ℃ for 0.5h at a rotating speed of 10000r/min, and filtering;
(4) dissolving 4.5 aluminum sol in 15.0g deionized water, adding 0.40g NaOH particles, and sequentially adding 10.0g coarse silica gel (SiO)2Content 98.0%) and 17.5g tetraethylammonium hydroxide solution (mass fraction of tetraethylammonium hydroxide in tetraethylammonium hydroxide solution is 25 wt%), stirring for 1h, adding the product obtained in step (3), and stirring for 30 min; transferring into a reaction kettle with a polytetrafluoroethylene lining for crystallization, crystallizing at 130 ℃ for 36 hours, filtering, washing, drying, and roasting at 550 ℃ for 2 hours.
Example 3
(1) Dissolving 3.0g of aluminum nitrate in 69.0g of deionized water, adding 2.4g of NaOH particles, sequentially adding 30.0g of ethyl orthosilicate and 28g of tetraethylammonium hydroxide solution (the mass fraction of the tetraethylammonium hydroxide in the tetraethylammonium hydroxide solution is 25 wt%), stirring uniformly, transferring into a reaction kettle with a polytetrafluoroethylene lining for crystallization, crystallizing at 100 ℃ for 10 hours, filtering, washing, drying, and roasting at 550 ℃ for 2 hours; the XRD spectrum of the obtained product has a peak at the 2 theta-22.4 degrees and has no peak at the 2 theta-21.2 degrees;
(2) uniformly mixing the product obtained in the step (1) with 50.0g of deionized water;
(3) adding 12.0g of ZSM-5 molecular sieve into the slurry obtained in the step (2), shearing at a high speed for 1h under the condition of 40 ℃ water bath, rotating speed of 15000r/min, and filtering;
(4) 3.0g of aluminum nitrate is dissolved in 15.0g of deionized water, 0.38g of NaOH particles are added, and 20.0g of white carbon black (SiO) is sequentially added2Content 98.0 wt%) and 38g tetraethylammonium hydroxide solution (mass fraction of tetraethylammonium hydroxide in tetraethylammonium hydroxide solution is 25 wt%), stirring for 1h, adding the product of step (3), and stirring for 30 min; transferring into a reaction kettle with a polytetrafluoroethylene lining for crystallization, crystallizing at 180 ℃ for 36 hours, filtering, washing, drying, and roasting at 550 ℃ for 2 hours.
Example 4
(1) 1.2g of aluminum chloride was dissolved in 6.7g of deionized water, and 0.25g of NaOH pellets were addedThen, 35.0mL of water glass (SiO) is added in turn2251g/L of concentration, 2.5 of modulus) and 22g of tetraethylammonium hydroxide solution (the mass fraction of tetraethylammonium hydroxide in the tetraethylammonium hydroxide solution is 25 wt%), stirring uniformly, transferring into a reaction kettle with a polytetrafluoroethylene lining for crystallization, crystallizing at 70 ℃ for 28h, filtering, washing, drying, and roasting at 550 ℃ for 2 h; the XRD spectrum of the obtained product has a peak at the 2 theta-22.4 degrees and has no peak at the 2 theta-21.2 degrees;
(2) uniformly mixing the product obtained in the step (1) with 60.0g of deionized water;
(3) adding 12.0g of ZSM-5 molecular sieve into the slurry obtained in the step (2), shearing at a high speed for 0.5h under the condition of 80 ℃ water bath, rotating at the speed of 15000r/min, and filtering;
(4) 2.0g of aluminum chloride was added to 15.0g of deionized water, 0.32g of NaOH pellets were added, and 15.0g of coarse silica gel (SiO) was added sequentially2Content 98.0 wt%) and 29g tetraethylammonium hydroxide solution (mass fraction of tetraethylammonium hydroxide in tetraethylammonium hydroxide solution: 25 wt%), stirring for 1h, then adding the product of step (3), and stirring for 30 min; transferring into a reaction kettle with a polytetrafluoroethylene lining for crystallization, crystallizing at 90 ℃ for 72 hours, filtering, washing, drying, and roasting at 550 ℃ for 2 hours.
Example 5
Referring to the method of example 1, except that the silicon source used in step (1) is a coarse silica gel, the SiO of which is2Amount of SiO2/Al2O3、H2O/SiO2、Na2O/SiO2R/SiO template2The ratio of (a) to (b) was the same as in example 1.
Comparative example 1
(1) Using water glass, aluminum sulfate and ethylamine water solution as raw materials according to the mol ratio of SiO2：A12O3：C2H5NH2：H20-40: 1: 10: 1792 gelatinizing, crystallizing at 140 deg.C for 3 days, and synthesizing large-grain cylindrical ZSM-5 molecular sieve (grain size 4.0 μm);
(2) pretreating the synthesized large-grain cylindrical ZSM-5 molecular sieve for 30min by using a sodium chloride salt solution (NaCl concentration is 5 wt%) of 0.5 wt% of methyl methacrylate, filtering, drying, adding into a beta molecular sieve suspension (a nano beta molecular sieve, the mass ratio of the ZSM-5 molecular sieve to the beta molecular sieve suspension is 1:10) which is dispersed by deionized water, adhering for 30min, filtering, drying, and roasting at 540 ℃ for 5h to obtain a nuclear phase molecular sieve;
(3) white carbon black and Tetraethoxysilane (TEOS) are used as silicon source, sodium aluminate and TEAOH are used as raw materials according to the proportion of TEAOH to SiO2:A12O3:H2Feeding materials with the ratio of O to 13:30:1:1500, adding the nuclear phase molecular sieve obtained in the step (2), and then putting the nuclear phase molecular sieve into a stainless steel kettle with a tetrafluoroethylene lining for crystallization at 140 ℃ for 54 hours;
(4) after crystallization, the mixture was filtered, washed, dried and then calcined at 550 ℃ for 4 hours.
Comparative example 2
Prepared according to the method of example 1, except that the steps (1) and (2) are not performed.
Dissolving 1.0g sodium metaaluminate in 15.0g deionized water, adding 0.36g NaOH granules, and sequentially adding 10.0g coarse-pore silica gel (SiO)2Content 98.0 wt.%) and 18g tetraethylammonium hydroxide solution (the weight fraction of tetraethylammonium hydroxide in the tetraethylammonium hydroxide solution is 25 wt.%), stirring for 1h, then adding 15.0g of ZSM-5 molecular sieve, and stirring for 30 min; transferring into a reaction kettle with a polytetrafluoroethylene lining for crystallization, crystallizing at 150 ℃ for 54h, filtering, washing, drying, and roasting at 550 ℃ for 2 h. A mixture of ZSM-5 and beta molecular sieve is obtained, and the core-shell molecular sieve is not obtained.
Comparative example 3
(1) Adding ZSM-5 into a suspension dispersed with deionized water and containing 0.5 wt% of beta molecular sieve (beta molecular sieve, the silica-alumina ratio is 30, the crystallinity is 95.0%, and the average grain size is 500nm), adhering for 30min, filtering, drying, and roasting at 540 ℃ for 2h to obtain a nuclear phase molecular sieve;
(2) dissolving 1.0g sodium metaaluminate in 15.0g deionized water, adding 0.36g NaOH granules, and sequentially adding 10.0g coarse-pore silica gel (SiO)2Content 98.0%) and 18g of tetraethylammonium hydroxide solution (mass fraction of tetraethylammonium hydroxide in the tetraethylammonium hydroxide solution: 25% by weight) to obtain a synthesis solution, and the nuclear phase molecular sieve of step (1) (of step (1) was added to the synthesis solutionThe weight ratio of the nuclear phase molecular sieve to the synthesis solution on a dry basis was 1: 30. ) Then the mixture is put into a stainless steel kettle with a tetrafluoroethylene lining for crystallization for 54 hours at the temperature of 140 ℃;
(3) after crystallization, the mixture is filtered, washed, dried and roasted at 550 ℃ for 2 hours. Obtaining the beta molecular sieve, and not obtaining the core-shell molecular sieve.
Molecular sieve evaluation reaction
The ZSM-5/β core-shell type molecular sieve samples prepared in examples 1 to 5 and comparative examples 1 to 3 above were ammonium exchanged to a sodium oxide content of less than 0.1 wt% to obtain an H-type molecular sieve, the ammonium exchange conditions being: molecular sieve: ammonium chloride: h2O is 1:0.5:10 weight ratio, the ammonium exchange temperature is 85 ℃, and the ammonium exchange time is 1 h. After ammonium exchange, filtering, washing and drying, and then roasting at 550 ℃ for 2 h.
The obtained core-shell molecular sieve is aged for 4 hours at the temperature of 800 ℃ by 100 percent of water vapor respectively. The evaluation was carried out on fixed bed micro-reverse FB, the feed oil was a hydroupgraded oil (see Table 2 for composition and physical properties), and the evaluation conditions were: the reaction temperature was 550 ℃, the agent-to-oil ratio (by weight) was 3, and the oil feed time was 150 seconds. The results are shown in Table 3.
TABLE 1
Example numbering
1
Comparative example 1
2
3
4
5
D1/D2
1:3
0.01
1:6
1:5
1:8
1:7
Ratio of core to shell
4:1
5:2
3:2
7:3
6:1
Thickness of shell molecular sieve, mum
0.5
0.06
1.0
0.5
0.5
1.0
Silica to alumina mole ratio of nuclear phase molecular sieve
30
30
30
30
30
30
Si/Al molar ratio of shell layer
31
31
32
34
38
31
The degree of coverage of the shell,%
95
75
85
87
90
92
Specific surface area, m2/g
529
398
531
524
519
507
The mesopore surface area accounts for the total surface area%
26
45
24
28
31
25
TABLE 2
Hydro-upgrading heavy oil properties
1
Density (20 ℃ C.)/(kg/m)3)
890.0
Sulfur/(microgram/gram)
<200
Ni + V/(microgram/gram)
<1
Content of hydrogen/%)
12.90
Content of naphthenic ring hydrocarbons/%)
44.67％
End point of distillation
630℃
TABLE 3
Sample source
Example 1
Comparative example 1
Comparative example 2
Comparative example 3
Example 2
Example 3
Example 4
Example 5
Reaction temperature/. degree.C
550
550
550
550
550
550
550
550
Reaction pressure/MPa
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
Reaction time/s
150
150
150
150
150
150
150
150
Agent to oil ratio/weight ratio
3
3
3
3
3
3
3
3
Product yield/%
H2-C2 (ethylene free)
3.25
1.98
2.07
1.97
2.49
2.24
4.02
2.14
Ethylene
7.18
4.85
5.18
3.54
6.02
6.35
6.58
6.12
C3-C4(propylene-free)
7.45
4.87
5.18
5.26
5.03
5.87
5.41
6.89
Propylene (PA)
7.95
5.98
6.35
5.14
7.72
7.64
7.45
7.04
Gasoline (gasoline)
13.98
10.28
11.15
11.94
9.89
10.20
11.30
11.64
Diesel oil
10.37
11.89
10.44
11.54
12.33
12.46
11.37
12.48
Heavy oil
49.06
59.75
59.04
60.21
56.08
54.52
53.06
52.99
Coke
0.76
0.40
0.59
0.40
0.42
0.73
0.81
0.70
As can be seen from table 3, the core-shell molecular sieve obtained by the synthesis method provided by the present invention has the advantages of higher ethylene yield, higher propylene yield, higher total yield of ethylene and propylene, and higher heavy oil conversion rate.
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