An ultra-stable y-type molecular sieve, a preparation method and application thereof

Abstract

The application discloses an ultra-stable Y-type molecular sieve and a preparation method and application thereof. The preparation method comprises the following steps: (1) mixing a first aluminum source, a first alkali source, a first Fe source, a first silicon source and water to obtain an Fe-containing Y molecular sieve directing body; (2) mixing a second aluminum source, a second silicon source, a second Fe source, a second alkali source, water and the directing body in step (1) to obtain a gel; (3) performing crystallization treatment on the gel in step (2); and (4) performing ammonium exchange, hydrothermal treatment and acid washing treatment on the crystallization product obtained in step (3) to obtain the ultra-stable Y-type molecular sieve. When the ultra-stable Y-type molecular sieve prepared by the method is used in a hydrocracking catalyst, the activity and selectivity are both significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of Y-type molecular sieve preparation technology, specifically relating to an ultrastable Y-type molecular sieve, its preparation method, and its application. Background Technology

[0002] Hydrocracking catalysts are bifunctional catalysts, and Y-type molecular sieves are widely used as the main cracking component in hydrocracking catalysts. Modification of the molecular sieve can improve its catalytic performance. Currently, there are many methods for modifying Y-type molecular sieves, but they are basically conventional post-treatment modifications. These methods have limited impact on the properties of Y-type molecular sieves, and other atoms are difficult to integrate into the Y-type molecular sieve framework. For example, CN104828839A discloses a method for preparing small-crystal Y-type molecular sieves. This method treats small-crystal NaY molecular sieves with an alkaline solution, and then performs dealumination and silicon replenishment modification on the resulting Y-type molecular sieve with an ammonium fluorosilicate aqueous solution, followed by hydrothermal treatment to further increase the framework silicon-aluminum ratio. However, this method suffers from problems such as complex modification processes and long modification times. Furthermore, the molecular sieve needs to undergo three processes: ammonium exchange, ammonium fluorosilicate modification, and hydrothermal treatment, resulting in low product yield and hindering large-scale industrial applications.

[0003] Microporous molecular sieves have limited pore sizes, and their reaction performance is restricted by the pore structure. Therefore, it is necessary to synthesize a stable Y-type molecular sieve with a hierarchical pore structure to overcome the diffusion limitations of macromolecular reactants.

[0004] In summary, constructing heteroatom-modified Y-type molecular sieves during the synthesis of Y-type molecular sieves, and then regulating the relevant properties of the molecular sieves, can greatly simplify the modification steps of Y-type molecular sieves, thereby preparing hydrocracking catalysts with better performance, which is an urgent problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an ultrastable Y-type molecular sieve, its preparation method, and its applications. The ultrastable Y-type molecular sieve of this invention is particularly suitable as an acidic component in hydrocracking catalysts, which is beneficial for improving the catalyst's activity and selectivity.

[0006] The first aspect of this invention provides a method for preparing an ultrastable Y-type molecular sieve, comprising the following steps:

[0007] (1) Mix the first aluminum source, the first alkali source, the first Fe source, the first silicon source and water to obtain a Fe-containing Y molecular sieve guide body;

[0008] (2) Mix the second aluminum source, the second silicon source, the second Fe source, the second alkali source, water and the guide body from step (1) to obtain a gel;

[0009] (3) Crystallize the gel from step (2);

[0010] (4) The crystallized product obtained in step (3) is subjected to ammonium exchange, hydrothermal treatment and acid washing to obtain ultra-stable Y-type molecular sieve, namely USY molecular sieve.

[0011] Further, in step (1), the method for preparing the Fe-containing Y molecular sieve guide preferably includes: mixing a first aluminum source, a first alkali source, a first Fe source, a first silicon source, and water, and allowing the mixture to stand to obtain the Fe-containing Y molecular sieve guide. The first Fe source is selected from at least one of ferric chloride, ferric sulfate, and ferric nitrate. The first aluminum source is selected from at least one of sodium aluminate and aluminum sulfate. The first alkali source is selected from at least one of NaOH and KOH. The first silicon source is selected from at least one of silica sol and water glass.

[0012] Further, in step (1), in the method for preparing the Fe-containing Y molecular sieve guide, the first aluminum source is calculated as Al2O3, the first alkali source is calculated as NaOH, the first Fe source is calculated as Fe2O3, the first silicon source is calculated as SiO2, and the molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O is 1:(11~42):(0.05~10.0):(5~25):(180~450), preferably 1:(15~35):(0.05~8.0):(5~18):(180~400).

[0013] Furthermore, in step (1), in the preparation method of the Fe-containing Y molecular sieve guide, preferably, the standing temperature is 10-50°C and the standing time is 15-35 hours.

[0014] Further, in step (1), in the method for preparing the Fe-containing Y molecular sieve guide, preferably, the first aluminum source and the first alkali source are mixed and dissolved in water, and then the first Fe source and the first silicon source are added in sequence, mixed evenly, and allowed to stand to obtain the Fe-containing Y molecular sieve guide.

[0015] Further, in step (2), the matrix mixture is a second aluminum source, a second silicon source, a second Fe source, a second alkali source, and water.

[0016] Further, in step (2), the second Fe source is selected from at least one of ferric chloride, ferric sulfate, and ferric nitrate. The second aluminum source is selected from at least one of sodium aluminate and aluminum sulfate. The second alkali source is selected from at least one of NaOH and KOH. The second silicon source is selected from at least one of silica sol and water glass.

[0017] Further, in step (2), in the matrix mixture, the second aluminum source is calculated as Al2O3, the second alkali source is calculated as NaOH, the second Fe source is calculated as Fe2O3, and the second silicon source is calculated as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O is 1:(1.5~15.0):(0.05~12.0):(1.5~12.0):(80~400), preferably 1:(1.5~10.0):(0.05~8.0):(1.5~8.0):(80~350).

[0018] Furthermore, in step (2), the amount of Fe-containing Y molecular sieve guide added is 10.0% to 45.0% of the total mass of the matrix mixture.

[0019] Further, in step (2), the second Fe source is introduced into the reaction system as a second Fe source feed, and the second Fe source feed is preferably prepared by at least one of the following methods:

[0020] a. At least a portion of the second Fe source and at least a portion of the second silicon source are used to form a second Fe source feed.

[0021] b. At least a portion of the second Fe source and at least a portion of the second aluminum source are used to form a second Fe source feed.

[0022] c. At least a portion of the second Fe source, together with at least a portion of the second aluminum source and at least a portion of the second silicon source, forms the second Fe source feed.

[0023] Further, in step (2), the Fe mass content (based on oxides) in the second Fe source feed is 0.5% to 12.0%, preferably 4.0% to 12.0%. Preferably, the second Fe source feed is ultrasonically treated and then subjected to a settling process (preferably, the settling time is 1 to 48 hours, more preferably 12 to 24 hours) before being introduced into the reaction system. Preferably, the ultrasonic treatment conditions are as follows: temperature 20 to 80°C, more preferably 20 to 60°C, ultrasonic frequency 20 to 50 kHz, time 1 to 8 hours, more preferably 1 to 4 hours.

[0024] Further, in step (2), the matrix mixture (second aluminum source, second silicon source, second Fe source, second alkali source and water) is mixed with the guide body from step (1) to obtain a gel. Specifically, the second alkali source and the second silicon source are mixed evenly with water, and then the guide body, the second Fe source and the second aluminum source obtained in step (1) are added in sequence and mixed evenly to obtain a gel.

[0025] Further, in step (2), the matrix mixture (second aluminum source, second silicon source, second Fe source, second alkali source and water) is mixed with the guide body from step (1) to obtain a gel. Preferably, the second Fe source is introduced into the reaction system as a second Fe source feed. Specifically, the second alkali source and the remaining second silicon source are mixed evenly with water, and then the guide body obtained in step (1), the second Fe source feed, and the remaining second aluminum source are added in sequence and mixed evenly to obtain a gel. The remaining second silicon source or the remaining second aluminum source refers to the second silicon source or the second aluminum source remaining after the second silicon source or the second aluminum source used in preparing the second B source feed.

[0026] Furthermore, in step (3), the crystallization adopts a three-stage temperature-increasing crystallization method. The first-stage crystallization temperature is 30-40°C, the second-stage crystallization temperature is 30-35°C higher than the first-stage temperature, and the third-stage crystallization temperature is 25-50°C higher than the second-stage temperature, with the highest temperature not exceeding 110°C. The crystallization time for each stage is 12-36 hours, preferably 15-24 hours.

[0027] Further, in step (4), the ammonium exchange is a conventional ammonium exchange. The ammonium salt used can be one or more of ammonium chloride, ammonium nitrate, and ammonium sulfate, wherein the concentration of the ammonium salt solution is 0.1–3.0 mol / L, the pH value is 1.0–7.0, preferably 2.0–7.0. The ammonium exchange temperature is 30–90℃, preferably 40–60℃, and the number of ammonium exchanges is 1–5. The solid-liquid volume ratio of each ammonium exchange is 1:10–1:20, and the treatment time for each ammonium exchange is 3–6 hours.

[0028] Further, in step (4), the hydrothermal treatment is performed 1 to 3 times, preferably 2 times, and the conditions for each hydrothermal treatment are as follows: temperature of 500 to 650°C, 100% steam treatment, and treatment time of 1 to 6 hours. The steam treatment can be closed steam treatment or flowing steam treatment, preferably flowing steam treatment.

[0029] Further, in step (4), the acid used in the pickling treatment is selected from at least one of citric acid, oxalic acid, and tartaric acid, and the acid concentration is 0.1–3.0 mol / L. The solid-liquid ratio in the pickling treatment is 1.0 g: (5.0–20.0) mL, the temperature of the pickling treatment is 30.0–95.0 °C, and the pickling time is 1–6 hours.

[0030] The second aspect of the present invention provides an ultrastable Y-type molecular sieve prepared by the above method.

[0031] Furthermore, the molecular sieve has the following properties: the mesoporous pore volume accounts for 35% to 65% of the total pore volume of the molecular sieve, preferably 35% to 55%.

[0032] Furthermore, the molecular sieve has the following properties: a specific surface area of ​​550–655 m². 2 / g, with a pore volume of 0.42~0.48mL / g.

[0033] Furthermore, in the molecular sieve, the average size of the crystal grains is 0.4–1.2 μm, preferably 400–600 nm.

[0034] Furthermore, the unit cell constant of the molecular sieve is

[0035] Furthermore, in the molecular sieve, the SiO2 / Al2O3 molar ratio is 12.0 to 24.0, preferably 17.0 to 20.0.

[0036] A third aspect of the present invention provides the application of the above-described molecular sieve in hydrocracking catalysts.

[0037] Furthermore, the application is to use USY molecular sieves in the manufacture of flexible hydrocracking catalysts.

[0038] Furthermore, the hydrocracking catalyst comprises a USY molecular sieve and a hydrocracking active metal component. The hydrocracking active metal is preferably a Group VIB or Group VIII metal, more preferably molybdenum, tungsten, or nickel. Based on the weight of the catalyst, the content of the USY molecular sieve is 15.0%-45.0%, the content of molybdenum (calculated as oxide) is 3.0%-12.0%, the content of tungsten (calculated as oxide) is 10.0%-18.0%, and the content of nickel (calculated as oxide) is 2.0%-8.0%.

[0039] Furthermore, the hydrocracking catalyst also includes alumina, with the alumina content ranging from 40% to 70% based on the weight of the catalyst.

[0040] Furthermore, the hydrocracking catalyst is particularly suitable for the catalytic cracking of polycyclic macromolecules. The feedstock can be vacuum gas oil with an initial boiling point of 350-370℃ and a final boiling point of 515-540℃. The main target products are heavy naphtha and jet fuel.

[0041] Furthermore, before use, the hydrogenation catalyst can be pre-sulfurized according to conventional methods in the art. The pre-sulfurization method can be: pre-sulfurizing the hydrogenation catalyst with sulfur, hydrogen sulfide or sulfur-containing raw materials in the presence of hydrogen at 165-320°C.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] Conventional Y-type molecular sieves have a relatively stable framework, and even hydrothermal treatment results in a limited number of mesopores. The inventors discovered that introducing Fe atoms into the molecular sieve framework, due to the larger bond length of the Fe-O bond compared to the Al-O bond length, is more conducive to reducing the framework distortion of heteroatom-modified Y-type molecular sieves, thus weakening the framework's stability. Furthermore, combined with the hydrothermal treatment and acid washing processes, which remove non-framework iron and aluminum from the molecular sieve channels, the proportion of mesopores in the molecular sieve is further increased, thereby improving the overall performance of the Y-type molecular sieve.

[0044] The Fe-modified Y molecular sieve of this invention differs from previous post-processing modified Y molecular sieves. Instead, Fe is first introduced into the guiding agent during Y molecular sieve synthesis to form crystal nuclei containing unstable "sites." Then, Fe is introduced again into the matrix solution used for Y molecular sieve synthesis. This "two-step method" controls both the nucleation and crystal growth processes, resulting in a more significant modification effect of heteroatoms (Fe) on the Y molecular sieve. The inherent properties of Fe atoms are fully utilized to promote framework instability. Finally, combined with the dealumination process in a hydrothermal manner, the generation of mesopores in the Y molecular sieve is significantly promoted, thereby greatly increasing the proportion of mesopores in the total pore volume of the Y molecular sieve. When this Y molecular sieve is used as a hydrocracking catalyst, its adsorption, diffusion, and shape selectivity are improved, enhancing reaction activity and selectivity.

[0045] The method of this invention can yield USY-type molecular sieves with high silica-to-alumina ratio, large specific surface area, and large pore volume, which can be used as cracking components in hydrocracking catalysts. The flexible hydrocracking catalysts prepared from these sieves exhibit significantly improved activity and selectivity. Attached Figure Description

[0046] Figure 1 The image shows the XRD pattern of the USY molecular sieve obtained in Example 1. Detailed Implementation

[0047] The technical solutions and effects of the present invention will be further illustrated below with reference to the embodiments, but the invention is not limited to the following embodiments.

[0048] In this invention, the pore volume, pore distribution, most probable pore size, and specific surface area of ​​the molecular sieve are determined using a physical adsorption instrument via a low-temperature nitrogen adsorption-desorption method. The pore volume and pore size distribution are obtained using the BJH method, and the specific surface area is obtained using the BET method.

[0049] In this invention, X-ray diffraction (XRD) was used to determine the phase composition and cell constant of the molecular sieve, and the Breck-Flanigen formula was used to calculate the silicon-to-aluminum ratio of the molecular sieve. The experimental conditions were: CuKα radiation, tube voltage 40 kV, and tube current 40 mA.

[0050] In this invention, scanning electron microscopy is used to statistically analyze the particle size distribution of molecular sieves.

[0051] In this invention, the distillation range of heavy naphtha is 65–177°C, and the distillation range of jet fuel is 177–260°C.

[0052] In this invention, the yield of heavy naphtha refers to the mass ratio of heavy naphtha to fresh hydrocracking feedstock (vacuum oil) in the hydrocracking products, and the yield of jet fuel refers to the mass ratio of jet fuel to fresh hydrocracking feedstock in the hydrocracking products.

[0053] Example 1

[0054] (1) Preparation of Fe-containing Y-type molecular sieve guide: The first Fe source was ferric chloride, the first aluminum source was sodium aluminate, the first alkali source was NaOH, and the first silicon source was silica sol. The first aluminum source and the first alkali source were mixed and dissolved in water, then the first Fe source and the first silicon source were added sequentially, mixed thoroughly, and allowed to stand to obtain the Fe-containing Y-type molecular sieve guide. The first aluminum source was calculated as Al2O3, the first alkali source as NaOH, the first Fe source as Fe2O3, and the first silicon source as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the feed was 1:32:0.80:14:320. The standing temperature was 45℃, and the standing time was 18 hours.

[0055] (2) Preparation of matrix mixture; the second Fe source in the matrix mixture is ferric chloride, the second aluminum source is sodium aluminate and aluminum sulfate (the molar ratio of sodium aluminate and aluminum sulfate, calculated as aluminum, is 1:0.55), the second alkali source is selected from NaOH, and the second silicon source is water glass. In the matrix solution, the second aluminum source is calculated as Al2O3, the second alkali source is calculated as NaOH, the second Fe source is calculated as Fe2O3, and the second silicon source is calculated as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the feed is 1:5.5:0.40:5.4:140. The amount of Fe-containing Y molecular sieve guide added in step (1) is 16.0% of the total mass of the matrix mixture. The second Fe source is dissolved in the aqueous solution of the second aluminum source sodium aluminate, wherein the mass content of Fe (calculated as oxide) is 6.0%. After ultrasonic treatment (frequency 35kHz) for 5h and a standing process for 20h, the second Fe source feed is obtained. Mix the second alkali source and the second silicon source with the remaining water until homogeneous, then add the guide body obtained in step (1), the second Fe source feed, and the second aluminum source aluminum sulfate in sequence, mix them until homogeneous, and obtain a gel.

[0056] (3) The gel obtained in step (2) is subjected to crystallization treatment; the crystallization adopts a three-stage temperature-increasing crystallization, with the first-stage crystallization temperature at 30℃, the second-stage crystallization temperature at 65℃, and the third-stage crystallization temperature at 100℃. The crystallization time for each stage is 20h.

[0057] (4) The crystallized product obtained in step (3) is subjected to ammonium exchange, hydrothermal treatment, and acid washing to obtain USY molecular sieve (its XRD is shown in Figure 3). Figure 1 ,Depend on Figure 1 As can be seen, it exhibits diffraction peaks characteristic of Y-type molecular sieves. Ammonium exchange was performed using conventional methods. The ammonium salt used was ammonium nitrate, with a concentration of 0.1 mol / L and a pH of 6.7. The ammonium exchange temperature was 60℃, and the exchange was performed twice. The solid-liquid volume ratio for each exchange was 1:10, and the treatment time was 6 hours. Hydrothermal treatment was performed twice, with the following conditions: temperature 620℃, 100% steam, and treatment time 6 hours. The steam treatment process used flowing steam. Then, 0.3 mol / L citric acid was used at a solid-liquid ratio of 1.0 g: 6.0 mL at 80℃ for 4 hours.

[0058] Example 2

[0059] (1) Preparation of Fe-containing Y-type molecular sieve guide: The first Fe source was ferric chloride, the first aluminum source was sodium aluminate, the first alkali source was NaOH, and the first silicon source was silica sol. The first aluminum source and the first alkali source were mixed and dissolved in water, then the first Fe source and the first silicon source were added sequentially, mixed evenly, and allowed to stand to obtain the Fe-containing Y-type molecular sieve guide. The first aluminum source was calculated as Al2O3, the first alkali source as NaOH, the first Fe source as Fe2O3, and the first silicon source as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the Y-type molecular sieve guide was 1:28:0.6:16:340. The standing temperature was 40℃, and the standing time was 24 hours.

[0060] (2) Preparation of matrix mixture; the second Fe source in the matrix mixture is ferric sulfate, the second aluminum source is sodium aluminate and aluminum sulfate (the molar ratio of sodium aluminate and aluminum sulfate, calculated as aluminum, is 1:0.53), the second alkali source is selected from NaOH, and the second silicon source is water glass. In the matrix solution, the second aluminum source is calculated as Al2O3, the second alkali source is calculated as NaOH, the second Fe source is calculated as Fe2O3, and the second silicon source is calculated as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the feed is 1:4.8:0.4:6.2:180. The amount of Fe-containing Y molecular sieve guide added in step (1) is 15.0% of the total mass of the matrix mixture. The second Fe source is dissolved in the aqueous solution of the second aluminum source sodium aluminate, wherein the mass content of Fe (calculated as oxide) is 8.0%. After ultrasonic treatment (frequency 35kHz) for 3h and a standing process for 18h, the second Fe source feed is obtained. Mix the second alkali source and the second silicon source with the remaining water until homogeneous, then add the guide body obtained in step (1), the second Fe source feed, and the second aluminum source aluminum sulfate in sequence, mix them until homogeneous, and obtain a gel.

[0061] (3) The gel obtained in step (2) is subjected to crystallization treatment; the crystallization is carried out by three-stage temperature rise crystallization, with the first-stage crystallization temperature being 30℃, the second-stage crystallization temperature being 65℃, and the third-stage crystallization temperature being 100℃. The crystallization time for each stage is 18h.

[0062] (4) The crystallized product obtained in step (3) was subjected to ammonium exchange, hydrothermal treatment, and acid washing to obtain USY molecular sieve. The ammonium exchange was a conventional ammonium exchange. The ammonium salt used was ammonium nitrate, with a concentration of 0.1 mol / L and a pH of 6.8. The ammonium exchange temperature was 60℃, and the ammonium exchange was performed twice. The solid-liquid volume ratio for each ammonium exchange was 1:10, and the treatment time for each ammonium exchange was 6 hours. The hydrothermal treatment was performed twice, with the following conditions for each hydrothermal treatment: temperature of 620℃, 100% steam treatment, and treatment time of 6 hours. The steam treatment process was a flowing steam treatment. Then, 0.3 mol / L citric acid was used at a solid-liquid ratio of 1.0 g: 6.0 mL at 70℃ for 5 hours.

[0063] Example 3

[0064] (1) Preparation of Fe-containing Y-type molecular sieve guide: The first Fe source was ferric chloride, the first aluminum source was sodium aluminate, the first alkali source was NaOH, and the first silicon source was silica sol. The first aluminum source and the first alkali source were mixed and dissolved in water, then the first Fe source and the first silicon source were added sequentially, mixed evenly, and allowed to stand to obtain the Fe-containing Y-type molecular sieve guide. The first aluminum source was calculated as Al2O3, the first alkali source as NaOH, the first Fe source as Fe2O3, and the first silicon source as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the feed was 1:30:0.5:15:300. The standing temperature was 25℃, and the standing time was 22 hours.

[0065] (2) Preparation of matrix mixture; the second Fe source in the matrix mixture is ferric chloride, the second aluminum source is sodium aluminate and aluminum sulfate (the molar ratio of sodium aluminate and aluminum sulfate, calculated as aluminum, is 1:0.50), the second alkali source is selected from NaOH, and the second silicon source is water glass. In the matrix solution, the second aluminum source is calculated as Al2O3, the second alkali source is calculated as NaOH, the second Fe source is calculated as Fe2O3, and the second silicon source is calculated as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the feed is 1:5.0:0.43:5.5:140. The amount of Fe-containing Y molecular sieve guide added in step (1) is 10.0% of the total mass of the matrix mixture. The second Fe source is dissolved in the aqueous solution of the second aluminum source sodium aluminate, wherein the mass content of Fe is 10.0%. After ultrasonic treatment (frequency 35kHz) for 4 hours and a standing process for 18 hours, the second Fe source feed is obtained. Mix the second alkali source and the second silicon source with the remaining water until homogeneous, then add the guide body obtained in step (1), the second Fe source feed, and the second aluminum source aluminum sulfate in sequence, mix them until homogeneous, and obtain a gel.

[0066] (3) The gel obtained in step (2) is subjected to crystallization treatment; the crystallization is carried out by three-stage temperature rise crystallization, with the first-stage crystallization temperature being 30℃, the second-stage crystallization temperature being 65℃, and the third-stage crystallization temperature being 100℃. The crystallization time for each stage is 18h.

[0067] (4) The crystallized product obtained in step (3) was subjected to ammonium exchange, hydrothermal treatment, and acid washing to obtain USY molecular sieve. The ammonium exchange was a conventional ammonium exchange. The ammonium salt used was ammonium nitrate, with a concentration of 0.1 mol / L and a pH of 6.8. The ammonium exchange temperature was 60℃, and the ammonium exchange was performed twice. The solid-liquid volume ratio for each ammonium exchange was 1:10, and the treatment time for each ammonium exchange was 6 hours. The hydrothermal treatment was performed twice, with the following conditions for each hydrothermal treatment: temperature of 620℃, 100% steam treatment, and treatment time of 6 hours. The steam treatment process was a flowing steam treatment. Then, 0.3 mol / L citric acid was used at a solid-liquid ratio of 1.0 g: 6.0 mL at 60℃ for 3 hours.

[0068] Example 4

[0069] (1) Preparation of Fe-containing Y-type molecular sieve guide: The first Fe source was ferric chloride, the first aluminum source was sodium aluminate, the first alkali source was NaOH, and the first silicon source was silica sol. The first aluminum source and the first alkali source were mixed and dissolved in water, then the first Fe source and the first silicon source were added sequentially, mixed evenly, and allowed to stand to obtain the Fe-containing Y-type molecular sieve guide. The first aluminum source was calculated as Al2O3, the first alkali source as NaOH, the first Fe source as Fe2O3, and the first silicon source as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the feed was 1:30:0.5:15:300. The standing temperature was 25℃, and the standing time was 22 hours.

[0070] (2) Preparation of matrix mixture; the second Fe source in the matrix mixture is ferric chloride, the second aluminum source is sodium aluminate and aluminum sulfate (the molar ratio of sodium aluminate and aluminum sulfate, calculated as aluminum, is 1:0.5), the second alkali source is selected from NaOH, and the second silicon source is water glass. In the matrix solution, the second aluminum source is calculated as Al2O3, the second alkali source is calculated as NaOH, the second Fe source is calculated as Fe2O3, and the second silicon source is calculated as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the feed is 1:5.2:0.45:5.6:120. The amount of Fe-containing Y molecular sieve guide added in step (1) is 15.0% of the total mass of the matrix mixture. The second Fe source is dissolved in the aqueous solution of the second aluminum source aluminum sulfate, wherein the mass content of Fe is 12.0%. After ultrasonic treatment (frequency 40kHz) for 1 hour and a standing process, the standing time is 18 hours, to obtain the second Fe source feed. Mix the second alkali source and the second silicon source with the remaining water until uniform, and then add the guide body obtained in step (1), the second Fe source feed, and the second aluminum source sodium aluminate in sequence, mix them evenly, and obtain a gel.

[0071] (3) The gel obtained in step (2) is subjected to crystallization treatment; the crystallization adopts a three-stage temperature-increasing crystallization, with the first-stage crystallization temperature at 40℃, the second-stage crystallization temperature at 75℃, and the third-stage crystallization temperature at 110℃. The crystallization time for each stage is 12h.

[0072] (4) The crystallized product obtained in step (3) was subjected to ammonium exchange, hydrothermal treatment, and acid washing to obtain USY molecular sieve. The ammonium exchange was a conventional ammonium exchange. The ammonium salt used was ammonium nitrate, with a concentration of 0.1 mol / L and a pH of 6.8. The ammonium exchange temperature was 60℃, and the ammonium exchange was performed twice. The solid-liquid volume ratio for each ammonium exchange was 1:10, and the treatment time for each ammonium exchange was 6 hours. The hydrothermal treatment was performed twice, with the following conditions for each hydrothermal treatment: temperature of 620℃, 100% steam treatment, and treatment time of 6 hours. The steam treatment process was a flowing steam treatment. Then, 0.3 mol / L oxalic acid was used at a solid-liquid ratio of 1.0 g: 6.0 mL at 60℃ for 4 hours.

[0073] Example 5

[0074] (1) Preparation of Fe-containing Y-type molecular sieve guide: The first Fe source was ferric chloride, the first aluminum source was sodium aluminate, the first alkali source was NaOH, and the first silicon source was silica sol. The first aluminum source and the first alkali source were mixed and dissolved in water, then the first Fe source and the first silicon source were added sequentially, mixed evenly, and allowed to stand to obtain the Fe-containing Y-type molecular sieve guide. The first aluminum source was calculated as Al2O3, the first alkali source as NaOH, the first Fe source as Fe2O3, and the first silicon source as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the feed was 1:30:0.5:15:300. The standing temperature was 25℃, and the standing time was 22 hours.

[0075] (2) Preparation of matrix mixture; the second Fe source in the matrix mixture is ferric chloride, the second aluminum source is sodium aluminate and aluminum sulfate (the molar ratio of sodium aluminate and aluminum sulfate, calculated as aluminum, is 1:0.52), the second alkali source is selected from NaOH, and the second silicon source is water glass. In the matrix solution, the second aluminum source is calculated as Al2O3, the second alkali source is calculated as NaOH, the second Fe source is calculated as Fe2O3, and the second silicon source is calculated as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the feed is 1:5.2:0.45:5.6:120. The amount of Fe-containing Y molecular sieve guide added in step (1) is 15.0% of the total mass of the matrix mixture. The second Fe source is dissolved in the second silicon source water glass solution, wherein the mass content of Fe is 4.0%. After ultrasonic treatment (frequency 20kHz) for 4h and a standing process, the standing time is 18h, to obtain the second Fe source feed. Mix the second alkali source with the remaining water until homogeneous, then add the guide body obtained in step (1), the second Fe source feed, the second aluminum source sodium aluminate, and the second aluminum source aluminum sulfate in sequence, mix them until homogeneous, and obtain a gel.

[0076] (3) The gel obtained in step (2) is subjected to crystallization treatment; the crystallization is carried out by three-stage temperature rise crystallization, with the first-stage crystallization temperature being 30℃, the second-stage crystallization temperature being 65℃, and the third-stage crystallization temperature being 100℃. The crystallization time for each stage is 18h.

[0077] (4) The crystallized product obtained in step (3) was subjected to ammonium exchange, hydrothermal treatment, and acid washing to obtain USY molecular sieve. The ammonium exchange was a conventional ammonium exchange. The ammonium salt used was ammonium chloride, with a concentration of 0.1 mol / L and a pH of 5.2. The ammonium exchange temperature was 80℃, and the ammonium exchange was performed twice. The solid-liquid volume ratio for each ammonium exchange was 1:10, and the treatment time for each ammonium exchange was 4 hours. The hydrothermal treatment was performed twice, with the following conditions for each hydrothermal treatment: a temperature of 600℃, 100% steam treatment, and a treatment time of 4 hours. The steam treatment process was a flowing steam treatment. Then, 0.3 mol / L citric acid was used at a solid-liquid ratio of 1.0 g: 6.0 mL at 50℃ for 6 hours.

[0078] Example 6

[0079] (1) Preparation of Fe-containing Y-type molecular sieve guide: The first Fe source was ferric chloride, the first aluminum source was sodium aluminate, the first alkali source was NaOH, and the first silicon source was silica sol. The first aluminum source and the first alkali source were mixed and dissolved in water, then the first Fe source and the first silicon source were added sequentially, mixed evenly, and allowed to stand to obtain the Fe-containing Y-type molecular sieve guide. The first aluminum source was calculated as Al2O3, the first alkali source as NaOH, the first Fe source as Fe2O3, and the first silicon source as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the feed was 1:30:0.50:15:300. The standing temperature was 25℃, and the standing time was 22 hours.

[0080] (2) Preparation of matrix mixture; the second Fe source in the matrix mixture is ferric chloride, the second aluminum source is sodium aluminate and aluminum sulfate (the molar ratio of sodium aluminate and aluminum sulfate, calculated as aluminum, is 1:0.52), the second alkali source is selected from NaOH, and the second silicon source is water glass. In the matrix solution, the second aluminum source is calculated as Al2O3, the second alkali source is calculated as NaOH, the second Fe source is calculated as Fe2O3, and the second silicon source is calculated as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O in the feed is 1:5.2:0.45:5.6:120. The amount of Fe-containing Y molecular sieve guide added in step (1) is 15.0% of the total mass of the matrix mixture. The second Fe source is dissolved in water, in which the mass content of Fe (calculated as oxide) is 6.0%. After ultrasonic treatment (frequency 25kHz) for 4 hours and a settling process for 18 hours, the second Fe source feed is obtained. Mix the second alkali source and the second silicon source with the remaining water until uniform, and then add the guide body obtained in step (1), the second Fe source feed, the second aluminum source sodium aluminate, and the second aluminum source aluminum sulfate in sequence, mix them evenly, and obtain a gel.

[0081] (3) The gel obtained in step (2) is subjected to crystallization treatment; the crystallization is carried out by three-stage temperature rise crystallization, with the first-stage crystallization temperature being 30℃, the second-stage crystallization temperature being 65℃, and the third-stage crystallization temperature being 100℃. The crystallization time for each stage is 18h.

[0082] (4) The crystallized product obtained in step (3) was subjected to ammonium exchange, hydrothermal treatment, and acid washing to obtain USY molecular sieve. The ammonium exchange was a conventional ammonium exchange. The ammonium salt used was ammonium nitrate, with a concentration of 0.1 mol / L and a pH of 6.8. The ammonium exchange temperature was 60℃, and the ammonium exchange was performed twice. The solid-liquid volume ratio for each ammonium exchange was 1:10, and the treatment time for each ammonium exchange was 6 hours. The hydrothermal treatment was performed twice, with the following conditions for each hydrothermal treatment: temperature of 620℃, 100% steam treatment, and treatment time of 6 hours. The steam treatment process was a flowing steam treatment. Then, 0.3 mol / L citric acid was used at a solid-liquid ratio of 1.0 g: 6.0 mL at 80℃ for 4 hours.

[0083] Example 7

[0084] The difference from Example 1 is that the water vapor treatment process in step (4) is a closed process.

[0085] Comparative Example 1

[0086] Compared with Example 1, the difference is that the Y molecular sieve guide prepared in step (1) does not contain the first Fe source, but only the first aluminum source, the first alkali source, the first silicon source and water are mixed and left to stand to obtain the Y molecular sieve guide.

[0087] Comparative Example 2

[0088] Compared with Example 1, the difference is that in step (2), the amount of Fe-containing Y molecular sieve guide added to the matrix mixture is 8.0% of the total mass of the matrix solution.

[0089] Comparative Example 3

[0090] Compared with Example 1, the difference is that the three-stage temperature rise crystallization process was not used in step (3), but the crystallization temperature was 65°C for 54 hours.

[0091] Application examples

[0092] This invention provides examples of the application of molecular sieves in flexible hydrocracking catalysts: the molecular sieves, alumina, molybdenum oxide, tungsten oxide, nickel oxide and guar gum powder prepared in each example are mixed evenly in a certain proportion, an inorganic acid is added as a binder, the powder is uniformly rolled into shape, dried at 120°C for 4 hours, and then calcined at 500°C for 6 hours to obtain a hydrocracking catalyst, the properties of which are shown in Table 2. The catalyst numbers are A-1 to A-7 and D-1 to D-3 in sequence.

[0093] Catalyst Evaluation: The catalysts prepared above were evaluated using a 200 mL small-scale hydrocracking unit. The catalysts underwent a pre-sulfurization process before reaction. The properties of the feedstock used in the evaluation tests are shown in Table 3. The process conditions and reaction performance results of the evaluation tests are shown in Tables 4 and 5. When evaluating this flexible hydrocracking catalyst, the feedstock was sequentially passed through two beds: one for hydrorefining catalyst and the other for the flexible hydrocracking catalyst prepared above. During the hydrorefining catalyst bed, the organic nitrogen content in the feedstock was controlled to be less than 10 ppm.

[0094] Table 1 shows the properties of the molecular sieves prepared in each example.

[0095]

[0096] Table 2 Composition of hydrocracking catalyst

[0097]

[0098]

[0099] Table 3 Properties of the feedstock oil used in the evaluation test

[0100] <![CDATA[Density (20 °C), g / cm 3 > 0.89 Distillation range, °C IBP / EBP 355 / 511 Pour point, ℃ 32 Residual carbon, wt% 0.21 S, wt% 1.4 N, wt% 0.16

[0101] Table 4. Process conditions and reaction performance results of the catalyst evaluation test of the present invention.

[0102]

[0103] Table 5 compares the process conditions and reaction performance results of the catalyst evaluation test.

[0104]

[0105] As shown in Tables 4 and 5, when the conversion rate of the controlled reaction is the same, the catalyst of the present invention exhibits better reaction activity and selectivity for the target product.

[0106] The embodiments described above are merely detailed descriptions of the technical solutions of the present invention, but the present invention is not limited to the above embodiments, that is, the present invention does not depend on the steps described in the above embodiments to be implemented. In summary, any improvements made to the present invention by those skilled in the art, including the substitution of the raw materials and additives described in the present invention, the selection of specific implementation methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an ultrastable Y-type molecular sieve, characterized in that: The molecular sieve has the following properties: mesoporous pore volume accounts for 35% to 65% of the total pore volume of the molecular sieve; the preparation method of the molecular sieve includes the following steps: (1) Mix the first aluminum source, the first alkali source, the first Fe source, the first silicon source and water to obtain a Fe-containing Y molecular sieve guide body; (2) Mix the second aluminum source, the second silicon source, the second Fe source, the second alkali source, water and the guide body from step (1) to obtain a gel; (3) Crystallize the gel from step (2); (4) The crystallized product obtained in step (3) is subjected to ammonium exchange, hydrothermal treatment, and acid washing to obtain an ultrastable Y-type molecular sieve; The crystallization in step (2) adopts a three-stage temperature rise crystallization. The first-stage crystallization temperature is 30~40℃, the second-stage crystallization temperature is 30~35℃ higher than the first-stage temperature, and the third-stage crystallization temperature is 25~50℃ higher than the second-stage temperature, and the highest temperature does not exceed 110℃. In step (2), the amount of Fe-containing Y molecular sieve guide added is 10.0% to 45.0% of the total mass of the matrix mixture, and the matrix mixture is a second aluminum source, a second silicon source, a second Fe source, a second alkali source and water.

2. The preparation method according to claim 1, characterized in that: In step (1), the first aluminum source, the first alkali source, the first Fe source, the first silicon source and water are mixed and allowed to stand to obtain the Fe-containing Y molecular sieve guide body.

3. The preparation method according to claim 2, characterized in that: The settling temperature is 10~50℃, and the settling time is 15~35 hours.

4. The preparation method according to claim 1 or 2, characterized in that: The first aluminum source is calculated as Al2O3, the first alkali source as NaOH, the first Fe source as Fe2O3, and the first silicon source as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O is 1:(11~42):(0.05~10.0):(5~25):(180~450).

5. The preparation method according to claim 4, characterized in that: The first aluminum source is calculated as Al2O3, the first alkali source as NaOH, the first Fe source as Fe2O3, and the first silicon source as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O is 1:(15~35):(0.05~8.0):(5~18):(180~400).

6. The preparation method according to claim 1, characterized in that: In step (2), the second aluminum source is calculated as Al2O3, the second alkali source is calculated as NaOH, the second Fe source is calculated as Fe2O3, and the second silicon source is calculated as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O is 1:(1.5~15.0):(0.05~12.0):(1.5~12.0):(80~400).

7. The preparation method according to claim 6, characterized in that: In step (2), the second aluminum source is calculated as Al2O3, the second alkali source is calculated as NaOH, the second Fe source is calculated as Fe2O3, and the second silicon source is calculated as SiO2. The molar ratio of Al2O3:NaOH:Fe2O3:SiO2:H2O is 1:(1.5~10.0):(0.05~8.0):(1.5~8.0):(80~350).

8. The preparation method according to claim 1, characterized in that: In step (2), the second Fe source is introduced into the reaction system as a second Fe source feed, and the second Fe source feed is prepared by at least one of the following methods: a. At least a portion of the second Fe source and at least a portion of the second silicon source are used to form a second Fe source feed. b. At least a portion of the second Fe source and at least a portion of the second aluminum source are used to form a second Fe source feed. c. At least a portion of the second Fe source, together with at least a portion of the second aluminum source and at least a portion of the second silicon source, forms the second Fe source feed.

9. The preparation method according to claim 8, characterized in that: In step (2), the second Fe source feed is ultrasonically treated and then allowed to stand before being introduced into the reaction system.

10. The preparation method according to claim 9, characterized in that: The settling time is 1 to 48 hours.

11. The preparation method according to claim 10, characterized in that: The settling time is 12-24 hours.

12. The preparation method according to claim 8, characterized in that: In the second Fe source feed, the Fe mass content, calculated as oxides, is 0.5%~12.0%; And / or, the ultrasonic treatment conditions are as follows: temperature 20~80℃, ultrasonic frequency 20~50kHz, time 1~8h.

13. The preparation method according to claim 12, characterized in that: The ultrasonic treatment conditions are as follows: temperature 20~60℃, time 1~4h.

14. The preparation method according to claim 1, characterized in that: The first Fe source or the second Fe source is independently selected from at least one of ferric chloride, ferric sulfate, and ferric nitrate; the first aluminum source or the second aluminum source is independently selected from at least one of sodium aluminate and aluminum sulfate; the first alkali source or the second alkali source is independently selected from at least one of NaOH and KOH; and the first silicon source or the second silicon source is independently selected from at least one of silica sol and water glass.

15. The preparation method according to claim 1, characterized in that: The crystallization time for each stage is 12 to 36 hours.

16. The preparation method according to claim 15, characterized in that: The crystallization time for each stage is 15 to 24 hours.

17. The preparation method according to claim 1, characterized in that: In step (4), the hydrothermal treatment is performed 1 to 3 times, and the conditions for each hydrothermal treatment are as follows: temperature is 500 to 650°C, treatment time is 1 to 6 hours under 100% water vapor treatment conditions.

18. The preparation method according to claim 17, characterized in that: The steam treatment is either a closed steam treatment or a flowing steam treatment.

19. The preparation method according to claim 18, characterized in that: The steam treatment is a flowing steam treatment.

20. The preparation method according to claim 1, characterized in that: In step (4), the acid used in the pickling treatment is selected from at least one of citric acid, oxalic acid, and tartaric acid, and the concentration of the acid solution is 0.1~3.0 mol / L; And / or, the solid-liquid ratio in the pickling process is 1.0g:5.0~20.0mL, the pickling temperature is 30.0~95.0℃, and the pickling time is 1~6 hours.

21. The ultrastable Y-type molecular sieve prepared by any one of the methods described in claims 1-20.

22. The molecular sieve according to claim 21, characterized in that: In the molecular sieve, the SiO2 / Al2O3 molar ratio is 7.0~27.5; and / or, the mesoporous pore volume accounts for 35%~55% of the total pore volume of the molecular sieve; and / or, the specific surface area is 550~655 m². 2 / g, with a pore volume of 0.42~0.48mL / g; and / or, with an average grain size of 0.4~1.2μm; and / or, with a cell constant of 23.28~24.40Å.

23. The molecular sieve according to claim 22, characterized in that: In the molecular sieve, the SiO2 / Al2O3 molar ratio is 17.0~20.0; and / or, the mesoporous pore volume accounts for 38%~55% of the total pore volume of the molecular sieve; and / or, the average size of the crystals is 400~600 nm.

24. The use of the ultrastable Y-type molecular sieve according to any one of claims 21-23 in hydrocracking catalysts.

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