Amorphous silica-alumina coated y-zeolite composite material, method for preparing the same, and use thereof
By pretreating NaY molecular sieves with fluorosilicone compounds and mixing them with surfactants and aluminum sources, an amorphous silica-alumina shell is formed to coat Y-type molecular sieves. This solves the problem of low catalyst activity in high-nitrogen environments and achieves efficient heavy oil cracking and selectivity for target products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-05
- Publication Date
- 2026-06-05
AI Technical Summary
Existing hydrocracking catalysts exhibit low activity and poor nitrogen resistance in high-nitrogen crude oil environments, and the amorphous silica and alumina are not tightly bonded to the Y-type molecular sieve, which affects cracking performance.
After pretreatment of NaY molecular sieve, it is treated with fluorosilicone compounds and supplemented with silicon source. Combined with surfactant, it is mixed with aluminum source in acidic environment to form an amorphous silicon-aluminum shell coating Y-type molecular sieve, forming a core-shell structure and optimizing its specific surface area, pore volume and acid properties.
The prepared catalyst exhibits high nitrogen resistance and high target selectivity, making it suitable for the stepwise cracking of heavy and inferior oils. It improves the cracking efficiency of heavy oil macromolecules and reduces post-processing steps and costs.
Smart Images
Figure CN122141735A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of molecular sieves, specifically to an amorphous silica-alumina coated Y-type molecular sieve composite material, its preparation method, and its application. Background Technology
[0002] Molecular sieves and amorphous silica-alumina are commonly used acidic components in hydrocracking catalysts. Amorphous silica-alumina is relatively weakly acidic, resulting in low catalyst activity when used alone. Molecular sieves, on the other hand, are characterized by strong acidity and numerous acid centers, leading to high activity in catalysts containing them and milder reaction conditions. Y-type molecular sieves are the most widely used molecular sieves in industrial hydrocracking catalysts. Hydrocracking catalysts containing Y-type molecular sieves exhibit advantages such as high cracking activity, good ring-opening properties, and good stability. However, the strong acidity of Y-type molecular sieves can easily lead to acid site poisoning in high-nitrogen crude oil environments. Amorphous silica-alumina supports, due to their high specific surface area, large pore volume and mesopore size, suitable moderate to strong acidity, and certain nitrogen resistance, demonstrate excellent performance under conditions of heavy and degraded crude oil.
[0003] Currently, the preparation of hydrocracking catalysts typically involves mechanically mixing Y-type molecular sieves with amorphous silica and alumina as the acidic component, without maximizing the combined advantages of both properties. For example, CN102451740A discloses a method for preparing a nano-Y-type molecular sieve / amorphous silica and alumina composite material. This method involves adding amorphous silica and alumina raw materials during the synthesis of Y-type molecular sieves to directly synthesize the composite material. However, this composite material still requires multiple post-processing steps during its later use, significantly increasing the cost. Furthermore, the bonding between amorphous silica and alumina and Y-type molecular sieves is not tight enough, which can easily affect subsequent cracking performance. "Preparation and Hydrocracking Performance of Y / ASA Composite Material", Meng Qinglei et al., Journal of Fuel Chemistry, 2012, 40(3), 354-358, uses synthesized NaY molecular sieves as the core phase, and still requires multiple post-processing steps during its later use, increasing the cost.
[0004] The challenge in this field is to uniformly coat amorphous silica and aluminum onto the outer surface of Y-type molecular sieves, so that the catalysts prepared from them have high nitrogen resistance and high target selectivity. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides an amorphous silica-alumina coated Y-type molecular sieve composite material, its preparation method, and its applications. This amorphous silica-alumina coated Y-type molecular sieve composite material, used as a cracking component in a hydrocracking catalyst, exhibits high nitrogen resistance and high target selectivity in the prepared hydrocracking catalyst.
[0006] The first aspect of this invention provides an amorphous silica-alumina coated Y-type molecular sieve composite material, the properties of which include: a total specific surface area of 200-900 m².2 / g, preferably 400-850mg 2 / g, with an external specific surface area of 100–700 m² 2 / g, preferably 250-550m 2 / g; total pore volume is 0.18-0.50 mL / g, preferably 0.20-0.45 mL / g; the thickness of the amorphous silicon-aluminum shell is 30-100 nm, preferably 30-60 nm, and the amount of medium-strong acid accounts for 30%-70% of the total acid content, preferably 30%-50%.
[0007] Furthermore, the total acid content of the amorphous silica-alumina coated Y-type molecular sieve composite material is 0.9–2.0 mmol / g.
[0008] Furthermore, based on the total mass of the amorphous silica-alumina coated Y-type molecular sieve composite material, the mass content of the amorphous silica-alumina shell layer is 10% to 80%, preferably 30% to 75%.
[0009] A second aspect of the present invention provides a method for preparing the above-mentioned amorphous silica-alumina coated Y-type molecular sieve composite material, comprising:
[0010] (1) Pretreatment of NaY molecular sieve;
[0011] (2) The molecular sieve pretreated in step (1) is subjected to dealuminization and silicon replenishment treatment to obtain modified Y molecular sieve;
[0012] (3) Stir the silicon source in an acidic environment to obtain solution 1;
[0013] (4) Stir the modified Y-type molecular sieve obtained in step (2) in an acidic environment and add a surfactant during the stirring process to obtain slurry 2;
[0014] (5) Mix the solution 1 and slurry 2, and add aluminum source during stirring until the aluminum source is completely dissolved. Adjust the pH and carry out the reaction. After the reaction is completed, perform post-processing to obtain amorphous silicon-aluminum coated Y-type molecular sieve composite material.
[0015] Further, in step (1), the pretreatment method includes: sequentially subjecting the NaY molecular sieve to ammonium exchange treatment, hydrothermal treatment and acid treatment to obtain the pretreated molecular sieve.
[0016] Furthermore, the properties of the NaY molecular sieve include: a SiO2 / Al2O3 molar ratio of 3.0 to 7.0, and a total specific surface area of 600 to 900 m². 2 / g, with a pore volume of 0.35~0.45mL / g.
[0017] Further, the ammonium exchange treatment includes: preparing an ammonium salt solution, and then treating it at 60–100°C for 0.5–5.0 h, with 1–5 ammonium exchange cycles; preferably, treating it at 70–95°C for 1.0–4.0 h, with 1–3 ammonium exchange cycles.
[0018] Furthermore, the ammonium salt solution is an aqueous solution of an ammonium salt, which is one or more of ammonium chloride, ammonium nitrate, and ammonium sulfate. The concentration of the ammonium salt solution is 0.5 mol / L to 5.0 mol / L.
[0019] Furthermore, after the ammonium exchange treatment, the mixture is filtered, dried, and then subjected to hydrothermal treatment. The drying temperature is 100–200°C, and the drying time is 12–48 hours.
[0020] Furthermore, the conditions for the hydrothermal treatment include: a hydrothermal treatment temperature of 350–950°C, preferably 400–900°C; a hydrothermal treatment pressure of 0.05–0.2 MPa, preferably 0.08–0.15 MPa; and a hydrothermal treatment time of 0.5–5.0 h, preferably 1.0–3.0 h.
[0021] Further, the acid treatment uses an acid solution concentration of 0.2–3.0 mol / L, a treatment temperature of 40–95°C, preferably 60–80°C, and a treatment time of 0.5–4.0 h, preferably 1.0–3.0 h. The acid solution can be at least one of inorganic acid solutions, organic acid solutions, or strong acid-weak base salt solutions, for example, one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, citric acid, stearic acid, oxalic acid, tartaric acid, aluminum sulfate, aluminum nitrate, aluminum phosphate, aluminum chloride, and ammonium chloride.
[0022] Further, in step (2), the molecular sieve pretreated in step (1) is subjected to dealuminization and silicon replenishment treatment using a fluorosilicone compound solution. Specifically, the molecular sieve pretreated in step (1) is first mixed with water, and the temperature is controlled at 50℃~95℃, preferably 65~95℃. Then, the fluorosilicone compound solution is added dropwise, and the reaction continues for 1~8h after the addition is completed.
[0023] Further, the molecular sieve pretreated in step (1) is mixed with water, and the solid-liquid mass-volume ratio of the two is 1:5 to 1:10 g / mL.
[0024] Further, the fluorosilicone compound is selected from one or more of ammonium fluorosilicate, fluorosilicic acid, silicon tetrafluoride, silicon trifluoride and silicon pentafluoride; the concentration of the fluorosilicone compound is 0.05 mol / L to 0.60 mol / L, preferably 0.10 mol / L to 0.50 mol / L.
[0025] Further, in step (2), after the molecular sieve pretreated in step (1) is subjected to dealumination and silicon replenishment treatment using a fluorosilicone compound solution, a certain amount of silicon source is preferably added and stirred to obtain modified Y molecular sieve. The silicon source is selected from one or more of tetraethyl orthosilicate and propyl orthosilicate. The amount of silicon source added is 1% to 10% of the mass of the molecular sieve pretreated in step (1), preferably 3% to 8%, based on SiO2. After adding the silicon source, the stirring time is 1 to 5 hours.
[0026] Further, after the dealuminization and silicon replenishment treatment in step (2), the modified Y molecular sieve is obtained by washing, filtering, and drying. The drying conditions are: drying at 90-200℃ for 6-24 hours.
[0027] Further, in step (2), the silicon-aluminum molar ratio (SiO2 / Al2O3) of the modified Y molecular sieve is in the range of 6.0 to 50.0, preferably 15 to 45.
[0028] Further, in step (3), the silicon source is one or more of tetraethyl orthosilicate, silica, acidic silica sol, and neutral silica sol. The acidic environment is an environment with a pH value of 1 to 5, preferably a pH value of 1 to 4. For example, the silicon source can be added to a hydrochloric acid solution and stirred. The stirring conditions are not particularly limited, as long as the silicon source is fully dissolved.
[0029] Furthermore, in step (4), the acidic environment is an environment with a pH value of 1 to 5, preferably a pH value of 1 to 4. For example, the modified Y-type molecular sieve can be added to the hydrochloric acid solution and stirred. The stirring conditions are not particularly limited, as long as the mixture is stirred evenly.
[0030] Further, in step (4), the surfactant is one or more of cationic surfactants, anionic surfactants, nonionic surfactants and amphoteric surfactants, preferably cationic surfactants, and more preferably one or more of tetraethylammonium bromide (TEAB), hexadecyltrimethylamine bromide (CTAB), tetraethylammonium hydroxide (TEAOH), tetramethylammonium bromide (TMAB), tetrapropylammonium bromide (TPAB), tetramethylammonium hydroxide (TMAOH), and tetrapropylammonium hydroxide (TPAOH).
[0031] Further, in step (4), the amount of surfactant added is 5% to 40% of the modified Y molecular sieve, based on the mass of the added modified Y molecular sieve.
[0032] Furthermore, in step (5), the aluminum source is one or more of aluminum isopropoxide, aluminum hydroxide, aluminum sulfate, aluminum nitrate, and aluminum chloride.
[0033] Further, in step (5), the mass ratio of the silicon source (calculated as SiO2), aluminum source (calculated as Al2O3) used in solution 1 and the modified Y molecular sieve used in slurry 2 is SiO2:Al2O3:modified Y molecular sieve = (0.25~3.0):(0.05~0.75):1.
[0034] Further, in step (5), the pH is adjusted to 6-8, preferably 6.5-7.5.
[0035] Furthermore, in step (5), the pH can be adjusted using a conventional alkaline solution, such as ammonia.
[0036] Furthermore, in step (5), the reaction temperature is 80-150°C, preferably 90-120°C, and the reaction time is 12-48h, preferably 16-30h.
[0037] Further, in step (5), the post-processing includes filtration, drying, and calcination. The drying conditions are: drying at 90–200°C for 6–24 hours. The calcination conditions are: calcination at 450–700°C for 2–5 hours.
[0038] The third aspect of the present invention provides an application of the above-mentioned amorphous silica-alumina coated Y-type molecular sieve composite material in hydrocracking catalysts.
[0039] Furthermore, amorphous silica-alumina coated Y-type molecular sieve composite materials, used as the cracking component of a hydrocracking catalyst, can achieve stepwise cracking of polycyclic aromatic hydrocarbon macromolecules. Specifically, heavy, low-quality oil with a high dry point (540–700℃) and high nitrogen content (nitrogen mass content not less than 1000 ppm) is used as raw material, including at least one of vacuum gas oil, fluidized bed gas oil, slurry bed gas oil, deasphalted oil, and waste plastic pyrolysis oil. The nitrogen mass content in the refined oil obtained by hydrorefining the heavy, low-quality oil is 10–80 ppm, preferably 30–80 ppm.
[0040] Further, the hydrocracking catalyst comprises an active metal component, the amorphous silica-alumina-coated Y-type molecular sieve composite material, and alumina. The active metal component comprises Group VIB metals and Group VIII metals. The Group VIB metals are preferably tungsten (W) and / or molybdenum (Mo), and the Group VIII metals are preferably cobalt (Co) and / or nickel (Ni). Based on the weight of the hydrocracking catalyst, the mass content of the amorphous silica-alumina-coated Y-type molecular sieve composite material is 6%–65%, preferably 10%–65%; the mass content of alumina is 5%–25%, preferably 8%–20%; the mass content of the Group VIB metals (based on oxides) is 10%–35%, preferably 15%–28%; and the mass content of the Group VIII metals (based on oxides) is 2%–10%, preferably 3%–8%.
[0041] Furthermore, the hydrocracking catalyst is used in the hydrocracking process under the following reaction conditions: in the presence of hydrogen, the reaction pressure is 4–20 MPa, the reaction temperature is 300–430 °C, the hydrogen-to-oil volume ratio is 500–1800:1, and the liquid hourly space velocity is 0.5–5.0 h⁻¹. -1 .
[0042] Compared with the prior art, the present invention has the following advantages:
[0043] This invention utilizes amorphous silica-alumina as a shell layer coated on the outer layer of a Y-type molecular sieve, forming a core-shell structure with a shell thickness of approximately 30–100 nm and a mesoporous microporous structure. This structure possesses a large specific surface area, large pore volume, and suitable medium-to-strong acid content. The amorphous silica-alumina-coated Y-type molecular sieve composite material of this invention serves as a cracking component in the hydrocracking catalyst for the production of heavy naphtha and / or jet fuel. The hydrocracking catalyst prepared from this material plays a stepwise cracking role in the macromolecular cracking process of heavy oil, exhibiting high nitrogen resistance and high target selectivity.
[0044] In the preparation method of this invention, the NaY molecular sieve is first pretreated with a specific pretreatment, followed by treatment with a fluorosilicon compound. This process is more conducive to the synergy with subsequent steps, thereby forming a uniform amorphous aluminosilicate shell layer on the outer surface of the Y molecular sieve. The hydrocracking catalyst prepared from this shell exhibits high nitrogen resistance and high target selectivity for the production of heavy naphtha and / or jet fuel. Preferably, a silicon source is introduced after the NaY molecular sieve undergoes dealumination and silicon replenishment, which further facilitates the uniform distribution of the amorphous aluminosilicate shell layer and adjusts the overall performance of the resulting amorphous aluminosilicate-coated Y-type molecular sieve. The catalyst prepared from this shell has strong adaptability to feedstock oils and is suitable for treating high-nitrogen, high-dry-point feedstock oils, significantly improving its nitrogen resistance and selectivity for the target products, heavy naphtha and jet fuel. In addition, the synthesis environment is sodium-free, and the synthesized amorphous aluminosilicate-coated Y-type molecular sieve composite material does not require further post-treatment processes such as ammonium exchange and can be directly used as a cracking component in the hydrocracking catalyst. Attached Figure Description
[0045] Figure 1 The image shows the SEM image of the amorphous silica-alumina coated Y-type molecular sieve composite material obtained in Example 1.
[0046] Figure 2 This is a TEM image of the amorphous silica-alumina coated Y-type molecular sieve composite material obtained in Example 1;
[0047] Figure 3 The pore size distribution diagrams are shown for the modified Y-type molecular sieve obtained in step (2) of Example 1 and the final amorphous silica-alumina coated Y-type molecular sieve composite material. Detailed Implementation
[0048] The following examples and comparative examples further illustrate the function and effect of the method of the present invention, but the following examples do not constitute a limitation on the method of the present invention. Unless otherwise specified, % in the context of the present invention should be understood as a percentage by mass.
[0049] In this invention, the sample SEM images were obtained using a JOEL JSM-6390 scanning electron microscope.
[0050] In this invention, the TEM images of the samples were obtained using a Tecnai G2-F20 high-resolution transmission electron microscope to analyze the microstructure of the catalyst, with an accelerating voltage of 200 kV.
[0051] In this invention, N2 adsorption-desorption characterization was performed using an ASAP 2420 from Microsystems, USA. Specific surface area (total specific surface area and external specific surface area) and pore volume were calculated using the DFT model and the t-plot model, respectively.
[0052] In this invention, the acid content of the sample was tested using a Micron 2920 chemisorption analyzer. Specifically, 100 mg of sample particles were placed in a quartz tube and activated with high-purity helium gas. After activation, ammonia gas was adsorbed. After 1 hour of adsorption, the sample was heated to 500°C at a heating rate of 10°C / min, and the desorbed ammonia gas signal was detected using a TCD detector. The NH3 temperature-programmed desorption method (NH3-TPD) utilizes NH3 as a basic gas probe molecule to determine the number and intensity of acidic sites in the zeolite sample. The peak area of the NH3-TPD curve represents the number of acidic sites, while the peak position and shape reflect the intensity of the acidic sites. The temperature range of 250-400°C is for medium-strong acids, and the temperature range of 150-500°C is for total acids.
[0053] Example 1
[0054] (1) Prepare a 2.0 mol / L ammonium chloride solution for NaY molecular sieve (silicon-aluminum molar ratio of SiO2 / Al2O3 = 4.9, total specific surface area of 849 m²). 2 The ammonium-type molecular sieve (with a pore volume of 0.37 mL / g) underwent ammonium exchange treatment once at 85℃ for 2 hours. After filtration, it was placed in a 120℃ oven for 24 hours. The dried ammonium-type molecular sieve was then subjected to hydrothermal treatment at 0.1 MPa and 600℃ for 2 hours, followed by treatment with 2.0 mol / L nitric acid solution at 60℃ for 1 hour to obtain the pretreated molecular sieve.
[0055] (2) Add deionized water at a solid-liquid mass-volume ratio of 1g / 10mL, weigh 10g of the pretreated molecular sieve obtained in step (1), stir evenly, and set the temperature to 80℃. Prepare a 0.20mol / L ammonium fluorosilicate solution, and add the ammonium fluorosilicate solution to the solution over 2 hours. After all the ammonium fluorosilicate solution has been added dropwise, continue stirring the system for 2 hours, then add 1.8g of tetraethyl orthosilicate, continue stirring for 2 hours, wash, filter, and dry at 120℃ for 12 hours to obtain a modified Y-type molecular sieve (the silicon-aluminum molar ratio of the modified Y-type molecular sieve is 32.6).
[0056] (3) Prepare an HCl solution with pH=1. Add 40g of tetraethyl orthosilicate (TEOS, containing 28% SiO2) while stirring to fully dissolve the silicon source. This solution is called solution 1.
[0057] (4) Prepare an HCl solution with pH=1, weigh 10g of the modified Y molecular sieve obtained in step (2), stir and disperse it in the HCl solution, add 3g of CTAB during the stirring process, stir for 4h to make the surfactant fully contact the molecular sieve, and record it as slurry 2.
[0058] (5) Mix solution 1 and slurry 2 and stir. Add 23.1 g of aluminum isopropoxide while stirring until the aluminum source is completely dissolved. Adjust the pH of the solution to 7 with ammonia water and place the solution at 90℃ for 24 h to crystallize. Filter the crystallized product, dry it at 120℃ for 12 h, and calcine it at 500℃ for 3 h to obtain an amorphous silicon-aluminum coated Y-type molecular sieve composite material.
[0059] Example 2
[0060] (1) Prepare a 2.0 mol / L ammonium chloride solution for NaY molecular sieve (silicon-aluminum molar ratio of SiO2 / Al2O3 = 4.9, total specific surface area of 849 m²). 2 The ammonium-type molecular sieve (with a pore volume of 0.37 mL / g) underwent ammonium exchange treatment once at 85℃ for 2 hours. After filtration, it was placed in a 120℃ oven for 24 hours. The dried ammonium-type molecular sieve was then subjected to hydrothermal treatment at 0.1 MPa and 600℃ for 2 hours, followed by treatment with 2.0 mol / L nitric acid solution at 60℃ for 1 hour to obtain the pretreated molecular sieve.
[0061] (2) Add deionized water at a solid-liquid mass-volume ratio of 1g / 10mL, weigh 10g of the pretreated molecular sieve obtained in step (1), stir evenly, and set the temperature to 80℃. Prepare a 0.20mol / L ammonium fluorosilicate solution, and add the ammonium fluorosilicate solution to the solution over 2 hours. After all the ammonium fluorosilicate solution has been added dropwise, continue stirring the system for 2 hours, then add 1.8g of tetraethyl orthosilicate, continue stirring for 1 hour, wash, filter, and dry at 150℃ for 10 hours to obtain a modified Y-type molecular sieve (the silicon-aluminum molar ratio of the modified Y-type molecular sieve is 32.6).
[0062] (3) Prepare an HCl solution with pH=1, and add 7.5g of acidic silica sol (SiO2 content 40%) while stirring to fully dissolve the silicon source. This solution is called solution 1.
[0063] (4) Prepare an HCl solution with pH=1, weigh 10g of the modified Y molecular sieve obtained in step (2), stir and disperse it in the HCl solution, add 4g of TEAOH during the stirring process, stir for 1h to make the surfactant fully contact the molecular sieve, and record it as slurry 2.
[0064] (5) Mix solution 1 and slurry 2 and stir. Add 9.8g of aluminum chloride while stirring until the aluminum source is completely dissolved. Adjust the pH of the solution to 6.5 with ammonia water and place the solution at 100℃ for 30h to crystallize. Filter the crystallized product, dry it at 150℃ for 10h, and calcine it at 550℃ for 3h to obtain the most amorphous silicon-aluminum coated Y-type molecular sieve composite material.
[0065] Example 3
[0066] (1) Prepare a 2.0 mol / L ammonium chloride solution for NaY molecular sieve (silicon-aluminum molar ratio of SiO2 / Al2O3 = 4.9, total specific surface area of 849 m²). 2 The ammonium-type molecular sieve (with a pore volume of 0.37 mL / g) underwent ammonium exchange treatment once at 85℃ for 2 hours. After filtration, it was placed in a 120℃ oven for 24 hours. The dried ammonium-type molecular sieve was then subjected to hydrothermal treatment at 0.1 MPa and 600℃ for 2 hours, followed by treatment with 2.0 mol / L nitric acid solution at 60℃ for 1 hour to obtain the pretreated molecular sieve.
[0067] (2) Add deionized water at a solid-liquid mass-volume ratio of 1g / 10mL, weigh 10g of the pretreated molecular sieve obtained in step (1), stir evenly, and set the temperature to 60℃. Prepare a 0.20mol / L ammonium fluorosilicate solution, and add the ammonium fluorosilicate solution to the solution over 2 hours. After all the ammonium fluorosilicate solution has been added dropwise, continue stirring the system for 2 hours, then add 1.8g of tetraethyl orthosilicate, continue stirring for 2 hours, wash, filter, and dry at 100℃ for 12 hours to obtain a modified Y-type molecular sieve (the silicon-aluminum molar ratio of the modified Y-type molecular sieve is 32.6).
[0068] (3) Prepare an HCl solution with pH=1, and add 76.9g of neutral silica sol (SiO2 content 26%) while stirring to fully dissolve the silicon source. This solution is called solution 1.
[0069] (4) Prepare an HCl solution with pH=1. Weigh 10g of the modified Y molecular sieve obtained in step (2) and stir and disperse it in the HCl solution. Add 14g of TPAOH during the stirring process and stir for 4h to allow the surfactant to fully contact the molecular sieve. This is recorded as slurry 2.
[0070] (5) Mix solution 1 and slurry 2 and stir. Add 13.0 g of aluminum nitrate while stirring until the aluminum source is completely dissolved. Adjust the pH of the solution to 7 with ammonia water and place the solution at 90℃ for 24 h to crystallize. Filter the crystallized product, dry it at 100℃ for 12 h, and calcine it at 500℃ for 5 h to obtain an amorphous silicon-aluminum coated Y-type molecular sieve composite material.
[0071] Example 4
[0072] (1) Prepare a 1.0 mol / L ammonium sulfate solution for NaY molecular sieve (silicon-aluminum molar ratio of SiO2 / Al2O3 = 4.9, total specific surface area of 849 m²). 2 The ammonium-type molecular sieve (with a pore volume of 0.37 mL / g) underwent ammonium exchange treatment once at 95℃ for 2 hours. After filtration, it was placed in a 100℃ oven for 24 hours. The dried ammonium-type molecular sieve was then subjected to hydrothermal treatment at 0.15 MPa and 700℃ for 3 hours, followed by treatment with 1.0 mol / L sulfuric acid solution at 80℃ for 1 hour to obtain the pretreated molecular sieve.
[0073] (2) Add deionized water at a solid-liquid mass-to-volume ratio of 1 g / 8 mL, weigh 10 g of the pretreated molecular sieve obtained in step (1), stir evenly, and set the temperature to 90℃. Prepare a 0.30 mol / L fluorosilicic acid solution, and add the fluorosilicic acid solution to the solution over 2 hours. After all the fluorosilicic acid solution has been added dropwise, continue stirring the system for 4 hours, then add 2.3 g of propylene silicate, continue stirring for 1 hour, wash, filter, and dry at 180℃ for 6 hours to obtain the modified Y-type molecular sieve (the silicon-aluminum molar ratio of the modified Y-type molecular sieve is 24.2 SiO2 / Al2O3).
[0074] (3) Prepare a nitric acid solution with pH=1. Add 28g of silica while stirring to fully dissolve the silicon source. This solution is called solution 1.
[0075] (4) Prepare a nitric acid solution with pH=1. Weigh 10g of the modified Y molecular sieve obtained in step (2), stir and disperse it in the nitric acid solution, add 3g of tetraethylammonium bromide during the stirring process, stir for 3h to allow the surfactant to fully contact the molecular sieve, and record it as slurry 2.
[0076] (5) Mix solution 1 and slurry 2 and stir. Add 13.1g of aluminum sulfate while stirring until the aluminum source is completely dissolved. Adjust the pH of the solution to 7.5 with ammonia water and place the solution at 120℃ for 16h to crystallize. Filter the crystallized product, dry it at 180℃ for 6h, and calcine it at 600℃ for 2h to obtain an amorphous silicon-aluminum coated Y-type molecular sieve composite material.
[0077] Example 5
[0078] (1) Prepare a 2.0 mol / L ammonium chloride solution for NaY molecular sieve (silicon-aluminum molar ratio of SiO2 / Al2O3 = 4.9, total specific surface area of 849 m²). 2 The ammonium-type molecular sieve (with a pore volume of 0.37 mL / g) underwent ammonium exchange treatment once at 85℃ for 2 hours. After filtration, it was placed in a 120℃ oven for 24 hours. The dried ammonium-type molecular sieve was then subjected to hydrothermal treatment at 0.1 MPa and 600℃ for 2 hours, followed by treatment with 2.0 mol / L nitric acid solution at 60℃ for 1 hour to obtain the pretreated molecular sieve.
[0079] (2) Add deionized water at a solid-liquid mass-to-volume ratio of 1 g / 10 mL, weigh 10 g of the pretreated molecular sieve obtained in step (1), stir evenly, and set the temperature to 80℃. Prepare a 0.20 mol / L ammonium fluorosilicate solution, and add the ammonium fluorosilicate solution to the solution over 2 hours. After all the ammonium fluorosilicate solution has been added dropwise, continue stirring the system for 2 hours to obtain the modified Y-type molecular sieve (the silicon-aluminum molar ratio SiO2 / Al2O3 of the modified Y-type molecular sieve is 17.6);
[0080] (3) Prepare an HCl solution with pH=1. Add 40g of tetraethyl orthosilicate (TEOS, containing 28% SiO2) while stirring to fully dissolve the silicon source. This solution is called solution 1.
[0081] (4) Prepare an HCl solution with pH=1, weigh 10g of the modified Y molecular sieve obtained in step (2), stir and disperse it in the HCl solution, add 3g of CTAB during the stirring process, stir for 4h to make the surfactant fully contact the molecular sieve, and record it as slurry 2.
[0082] (5) Mix solution 1 and slurry 2 and stir. Add 23.1 g of aluminum isopropoxide while stirring until the aluminum source is completely dissolved. Adjust the pH of the solution to 7 with ammonia water and place the solution at 90℃ for 24 h to crystallize. Filter the crystallized product, dry it at 120℃ for 12 h, and calcine it at 500℃ for 3 h to obtain an amorphous silicon-aluminum coated Y-type molecular sieve composite material.
[0083] Comparative Example 1
[0084] Compared with Example 1, the only difference is that step (2) is not performed during the preparation process.
[0085] Comparative Example 2
[0086] Compared with Example 1, the only difference is that CTAB is not added in step (4).
[0087] Comparative Example 3
[0088] Compared with Example 1, the only difference is that only steps (1) and (2) are performed in the preparation process to obtain the modified Y-type molecular sieve.
[0089] Comparative Example 4
[0090] (1) Prepare an HCl solution with pH=1. Add 40g of tetraethyl orthosilicate (TEOS, containing 28% SiO2) while stirring to fully dissolve the silicon source. This solution is denoted as solution 1.
[0091] (2) To prepare an HCl solution with pH = 1, weigh 10g of NaY molecular sieve (silicon-aluminum molar ratio of SiO2 / Al2O3 = 4.9, total specific surface area of 849m²). 2 / g, with a pore volume of 0.37mL / g), was dispersed in HCl solution by stirring. During the stirring process, 3g of CTAB was added and stirred for 4 hours to ensure that the surfactant and molecular sieve were in full contact. This was recorded as slurry 2.
[0092] (3) Mix solution 1 and slurry 2 and stir. Add 23.1g of aluminum isopropoxide while stirring until the aluminum source is completely dissolved. Adjust the pH of the solution to 7 with ammonia water and place the solution at 90℃ for 24h to crystallize. Filter the crystallized product, dry it at 120℃ for 12h, and calcine it at 500℃ for 3h to obtain the final product.
[0093] Table 1. Physicochemical properties of the products obtained from the examples and comparative examples.
[0094] Example 1 Example 2 Example 3 Example 4 Example 5 <![CDATA[Total specific surface area, m 2 / g]]> 802 822 761 718 675 Total pore volume, mL / g 0.37 0.30 0.35 0.40 0.41 <![CDATA[External specific surface area, m 2 / g]]> 542 543 510 475 438 Average amorphous silicon-aluminum shell thickness, nm 55 35 76 78 90 Amorphous silicon-aluminum content in the shell, wt% 48.5 33.6 53.8 59.5 66.3 Medium-strong acid content / total acid content, % 38 24 43 49 53 Total acid content, mmol / g 1.524 1.335 1.256 1.187 0.942
[0095] Continued from Table 1
[0096] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 <![CDATA[Total specific surface area, m 2 / g]]> 386 183 815 514 Total pore volume, mL / g 0.22 0.13 0.32 0.56 <![CDATA[External specific surface area, m 2 / g]]> 143 53 582 109 Average amorphous silicon-aluminum shell thickness, nm 15 — — 110 Amorphous silicon-aluminum content in the shell, wt% 12.1 — — 78.3 Medium-strong acid content / total acid content, % 7 — — 65
[0097] Experimental evaluation of cracking performance of amorphous silica-alumina coated Y molecular sieve composite materials:
[0098] Catalyst preparation method: The amorphous silica-alumina coated Y molecular sieve composite materials obtained in Examples 1, 2, and 5, and the products obtained in Comparative Examples 1, 3, and 4, were mixed with alumina, molybdenum oxide, and nickel nitrate (based on NiO content) in a ratio of 65:15:17:3 to prepare catalysts, which were respectively denoted as catalyst 1, catalyst 2, catalyst 3, catalyst 4, catalyst 5, and catalyst 6.
[0099] Catalyst evaluation conditions: The properties of the feedstock oil used in the experiment are shown in Table 2. The evaluation process conditions were: reaction pressure 15.0 MPa, volume hourly space velocity 0.7 h⁻¹. -1 The hydrogen-to-oil volume ratio was 1000:1, and the reaction temperature was 380℃. The comparison results are shown in Table 3.
[0100] Table 2 Properties of Crude Oil
[0101] <![CDATA[Density (20 °C), g / cm 3 > 0.9186 Distillation range / ℃ IBP / EBP 315 / 595 Nitrogen content, ppm 1365 Mass spectrometry composition, wt% Alkanes 15.3 Cycloalkanes 35.6 Aromatics 48.4 gelatin 0.7
[0102] Table 3 Product Distribution
[0103]
[0104] Continued from Table 3
[0105]
[0106] As shown in Table 3, when the reaction temperature is controlled at the same level, the organic nitrogen content of the feed oil in the hydrorefining catalyst bed needs to be controlled at 40 ppm. The tail oil yield of catalysts 1-3 is significantly lower than that of catalysts 4-6, while the heavy naphtha and jet fuel yields of catalysts 1-3 are higher than those of catalysts 4-6. This indicates that the amorphous silica-alumina coated Y molecular sieve composite material of the present invention has good nitrogen resistance and is suitable for the preparation of hydrocracking catalysts in high nitrogen reaction environments.
Claims
1. An amorphous silica-alumina coated Y-type molecular sieve composite material, characterized in that, The properties of the amorphous silica-alumina coated Y-type molecular sieve composite material include: a total specific surface area of 200–900 m². 2 / g, preferably 400-850mg 2 / g, with an external specific surface area of 100–700 m² 2 / g, preferably 250-550m 2 / g; total pore volume is 0.18-0.50 mL / g, preferably 0.20-0.45 mL / g; the thickness of the amorphous silicon-aluminum shell is 30-100 nm, preferably 30-60 nm, and the amount of medium-strong acid accounts for 30%-70% of the total acid content, preferably 30%-50%.
2. The amorphous silica-alumina coated Y-type molecular sieve composite material according to claim 1, characterized in that, Based on the total mass of the amorphous silica-alumina coated Y-type molecular sieve composite material, the mass content of the amorphous silica-alumina shell layer is 10% to 80%, preferably 30% to 75%.
3. The amorphous silica-alumina coated Y-type molecular sieve composite material according to claim 1, characterized in that, The total acid content of the amorphous silica-alumina coated Y-type molecular sieve composite material is 0.9–2.0 mmol / g.
4. A method for preparing an amorphous silica-alumina coated Y-type molecular sieve composite material, characterized in that, include: (1) Pretreatment of NaY molecular sieve; (2) The molecular sieve pretreated in step (1) is subjected to dealuminization and silicon replenishment treatment to obtain modified Y molecular sieve; (3) Stir the silicon source in an acidic environment to obtain solution 1; (4) Stir the modified Y-type molecular sieve obtained in step (2) in an acidic environment and add a surfactant during the stirring process to obtain slurry 2; (5) Mix the solution 1 and slurry 2, and add aluminum source during stirring until the aluminum source is completely dissolved. Adjust the pH and carry out the reaction. After the reaction is completed, perform post-processing to obtain amorphous silicon-aluminum coated Y-type molecular sieve composite material.
5. The method according to claim 4, characterized in that, In step (1), the pretreatment method includes: sequentially subjecting the NaY molecular sieve to ammonium exchange treatment, hydrothermal treatment and acid treatment to obtain the pretreated molecular sieve.
6. The method according to claim 4 or 5, characterized in that, The properties of the NaY molecular sieve include: a SiO2 / Al2O3 molar ratio of 3.0–7.0, and a total specific surface area of 600–900 m². 2 / g, with a pore volume of 0.35~0.45mL / g.
7. The method according to claim 5, characterized in that, The ammonium exchange treatment includes: preparing an ammonium salt solution, and then treating it at 60–100°C for 0.5–5.0 h, with 1–5 ammonium exchange cycles; preferably, treating it at 70–95°C for 1.0–4.0 h, with 1–3 ammonium exchange cycles. Preferably, the ammonium salt solution is an aqueous solution of an ammonium salt, wherein the ammonium salt is one or more selected from ammonium chloride, ammonium nitrate, and ammonium sulfate; and the concentration of the ammonium salt solution is 0.5 mol / L to 5.0 mol / L. And / or, the conditions for the hydrothermal treatment include: a hydrothermal treatment temperature of 350–950°C, preferably 400–900°C; a hydrothermal treatment pressure of 0.05–0.2 MPa, preferably 0.08–0.15 MPa; and a hydrothermal treatment time of 0.5–5.0 h, preferably 1.0–3.0 h. And / or, the acid treatment uses an acid solution concentration of 0.2–3.0 mol / L, an acid treatment temperature of 40–95°C, preferably 60–80°C, and an acid treatment time of 0.5–4.0 h, preferably 1.0–3.0 h; the acid solution is at least one of inorganic acid solution, organic acid solution, and strong acid-weak base salt solution.
8. The method according to claim 4, characterized in that, In step (2), the molecular sieve pretreated in step (1) is subjected to dealuminization and silicon replenishment treatment using a fluorosilicone compound solution. Specifically, the molecular sieve pretreated in step (1) is first mixed with water, and the temperature is controlled at 50℃~95℃, preferably 65~95℃. Then, a fluorosilicone compound solution is added dropwise, and the reaction continues for 1~8h after the addition is completed. And / or, the molecular sieve pretreated in step (1) is mixed with water, and the solid-liquid mass-volume ratio of the two is 1:5 to 1:10 g / mL; And / or, the fluorosilicone compound is selected from one or more of ammonium fluorosilicate, fluorosilicic acid, silicon tetrafluoride, silicon trifluoride and silicon pentafluoride; the concentration of the fluorosilicone compound is 0.05 mol / L to 0.60 mol / L, preferably 0.10 mol / L to 0.50 mol / L.
9. The method according to claim 4, characterized in that, In step (2), after the molecular sieve pretreated in step (1) is subjected to dealuminization and silicon replenishment treatment using a fluorosilicone compound solution, a silicon source is preferably added and stirred to obtain a modified Y molecular sieve. The silicon source is selected from one or more of tetraethyl orthosilicate and propyl orthosilicate. The amount of silicon source added is 1% to 10% of the mass of the molecular sieve pretreated in step (1), preferably 3% to 8%, based on SiO2. After adding the silicon source, the stirring time is 1 to 5 hours.
10. The method according to claim 4 or 9, characterized in that, In step (2), the silicon-aluminum molar ratio (SiO2 / Al2O3) of the modified Y molecular sieve is in the range of 6.0 to 50.0, preferably 15 to 45.
11. The method according to claim 4, characterized in that, In step (3), the silicon source is one or more of tetraethyl orthosilicate, silica, acidic silica sol, and neutral silica sol; the acidic environment is an environment with a pH value of 1 to 5, preferably with a pH value of 1 to 4.
12. The method according to claim 4, characterized in that, In step (4), the acidic environment is an environment with a pH value of 1 to 5, preferably with a pH value of 1 to 4; And / or, in step (4), the surfactant is one or more of cationic surfactants, anionic surfactants, nonionic surfactants and amphoteric surfactants, preferably cationic surfactants, and more preferably one or more of tetraethylammonium bromide, hexadecyltrimethylamine bromide, tetraethylammonium hydroxide, tetramethylammonium bromide, tetrapropylammonium bromide, tetramethylammonium hydroxide, and tetrapropylammonium hydroxide. And / or, in step (4), the amount of surfactant added is 5% to 40% of the modified Y molecular sieve, based on the mass of the added modified Y molecular sieve.
13. The method according to claim 4, characterized in that, In step (5), the aluminum source is one or more of aluminum isopropoxide, aluminum hydroxide, aluminum sulfate, aluminum nitrate, and aluminum chloride; And / or, the mass ratio of the silicon source (SiO2) and aluminum source (Al2O3) used in solution 1 to the modified Y molecular sieve used in slurry 2 is SiO2:Al2O3:modified Y molecular sieve = (0.25~3.0):(0.05~0.75):1; And / or, in step (5), the pH is adjusted to 6-8, preferably 6.5-7.5; And / or, in step (5), the temperature of the reaction is 80-150°C, preferably 90-120°C, and the reaction time is 12-48h, preferably 16-30h; And / or, in step (5), the post-processing includes filtration, drying and calcination; the drying conditions are: drying at 90-200°C for 6-24 hours; the calcination conditions are: calcination at 450-700°C for 2-5 hours.
14. The application of the amorphous silica-alumina coated Y-type molecular sieve composite material according to any one of claims 1-3 or the amorphous silica-alumina coated Y-type molecular sieve composite material prepared by any one of claims 4-13 in hydrocracking catalysts.