Composite catalysts, their preparation methods and applications

Abstract

This disclosure relates to a composite catalyst, its preparation method, and its application. The composite catalyst comprises a phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve, a second molecular sieve, and a support. Based on the dry weight of the composite catalyst, the content of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 5-35% by weight, the content of the second molecular sieve is 10-50% by weight, and the content of the support is 30-80% by weight. The second molecular sieve is a molecular sieve with a pore size of 0.56-0.75 nm, or it is a rare-earth-containing Y-type molecular sieve. The composite catalyst of this disclosure exhibits superior molecular diffusion performance, resulting in higher low-carbon olefin yields when used in LCO hydrocracking or heavy oil catalytic cracking.

Description

Technical Field

[0001] This disclosure relates to a composite catalyst, its preparation method, and its application. Background Technology

[0002] Ethylene and propylene are very important chemical raw materials. Currently, the world mainly uses naphtha steam cracking to produce low-carbon olefins. However, naphtha production is limited, while the global demand for low-carbon olefins is increasing. Therefore, developing and utilizing other raw materials to produce low-carbon olefins is of great significance.

[0003] In catalysts for producing low-carbon olefins, ZSM-5 molecular sieves with MFI topology and β-molecular sieves with BEA topology are commonly used. While ZSM-5 molecular sieves possess shape-selective properties, their small pore size hinders the diffusion and adsorption of large molecular reactants, especially cyclic hydrocarbons, resulting in low yields of low-carbon olefins. Currently, many synthetic routes exist based on ZSM-5 hierarchical porous molecular sieve materials, but these methods all have certain limitations, such as requiring the use of special raw materials or template agents to construct mesopores, or adding additional raw materials to the gel and then removing them through post-treatment, thus limiting their widespread application. Summary of the Invention

[0004] The purpose of this disclosure is to provide a composite catalyst, its preparation method, and its application to significantly improve the yield of low-carbon olefins.

[0005] To achieve the above objectives, in a first aspect, this disclosure provides a composite catalyst comprising a phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve, a second molecular sieve, and a support, wherein, based on the dry weight of the composite catalyst, the content of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 5-35% by weight, the content of the second molecular sieve is 10-50% by weight, and the content of the support is 30-80% by weight.

[0006] The phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve has a hollow structure, an average grain size of 0.2-3.0 μm, and a bulk silicon-aluminum molar ratio to surface silicon-aluminum molar ratio of 1.0-1.5; the phosphorus-aluminum molar ratio of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 0.1-1.5; and the total specific surface area of ​​the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 340-400 m². 2 / g, mesoporous specific surface area is 40-150m² 2 / g, wherein the mesoporous specific surface area accounts for 15-40% of the total specific surface area; the strong Brønsted acid content of the phosphorus-containing hollow ZSM-5 multi-level porous molecular sieve accounts for 65-80% of the total Brønsted acid content, and the strong Lewis acid content accounts for 50-75% of the total Lewis acid content.

[0007] The second molecular sieve is a molecular sieve with a pore size of 0.56-0.75 nm, or the second molecular sieve is a Y-type molecular sieve containing rare earth elements.

[0008] Optionally, the phosphorus-aluminum molar ratio of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 0.2-1.3.

[0009] Optionally, the average grain size of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve crystals is 0.4-2.5 μm, the ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio is 1.1-1.4, and the relative crystallinity is 75-90%.

[0010] Optionally, the total specific surface area of ​​the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 350-400 m². 2 / g, mesoporous specific surface area is 45-140m² 2 / g, wherein the mesoporous specific surface area accounts for 20-35% of the total specific surface area.

[0011] Optionally, the molecular sieve with an aperture size of 0.56-0.75 nm is one or more of the molecular sieves having structures of AET, AFR, AFS, AFI, BEA, BOG, CFI, CON, GME, IFR, ISV, LTL, MEI, MOR, OFF, and SAO; preferably at least one of Beta, SAPO-5, SAPO-40, SSZ-13, CIT-1, ITQ-7, ZSM-18, mordenite, and sodium chalcogenide.

[0012] The rare earth content of the Y-type molecular sieve, calculated as rare earth element oxides, is 2-25% by weight, and the rare earth element is lanthanum and / or cerium; the phosphorus content of the Y-type molecular sieve, calculated as P2O5, is 0-10% by weight; the Y-type molecular sieve is selected from one or more of REY molecular sieve, DASY molecular sieve, USY molecular sieve, phosphorus-containing DASY molecular sieve, phosphorus-containing USY molecular sieve, PSRY molecular sieve, HRY molecular sieve, HSY molecular sieve, SCY molecular sieve, and RSCY molecular sieve.

[0013] Optionally, the carrier is selected from one or more of natural clay, alumina carrier, silica carrier, aluminum phosphate carrier and silica-alumina oxide carrier;

[0014] Preferably, the silica support is one or more of neutral silica sol, acidic silica sol, or alkaline silica sol; the alumina support is one or more of alumina sol, acidified boehmite, hydrated alumina, and activated alumina; the aluminum phosphate support is aluminum phosphate gel; and the aluminosilicate support is selected from one or more of solid aluminosilicate materials, aluminosilicate sol, and aluminosilicate gel.

[0015] Optionally, the support comprises a silica support; based on the dry weight of the composite catalyst, the silica support contains 1-20% by weight of SiO2.

[0016] A second aspect of this disclosure provides a method for preparing the composite catalyst described in the first aspect of this disclosure, the method comprising: subjecting a slurry containing a support, a phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve, a second molecular sieve, and water to a first drying and optionally a first calcination.

[0017] Optionally, the preparation steps of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve include:

[0018] (1) Mix and stir the first organosilicon source and the first solvent at 30-50°C for 0.5-5 hours, then heat to 70-100°C and mix and stir for 2-10 hours. Mix the resulting mixed liquid with the first template agent at 20-30°C for 0.5-3.0 hours to obtain the first mixed product.

[0019] (2) Mix the first alkali metal hydroxide (calculated as alkali metal oxide), the second solvent, and the first aluminum source (calculated as Al2O3) in a molar ratio of (1.5-5):(60-350):1 at 20-80°C for 0.5-2.0 hours to obtain the second mixed product;

[0020] (3) The first mixed product and the second mixed product are mixed and then dynamically crystallized. The resulting solid is taken out and subjected to a second calcination to obtain the first solid product.

[0021] (4) The first solid product is mixed with the first alkaline solution, and the temperature is raised to the reaction temperature at a rate of 1-5℃ / min. The reaction is carried out at the reaction temperature for 10-90 min to obtain the second solid product. The reaction temperature is 60-90℃, and the alkaline content in the first alkaline solution is 0.45-2 mol / L.

[0022] (5) The second solid product is subjected to a first ammonium exchange and optionally a sixth calcination to obtain a third solid product;

[0023] (6) The third solid product is mixed with a second solution containing a phosphorus source, and the resulting first slurry is subjected to a second drying and a third calcination; or,

[0024] The preparation steps of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve include:

[0025] S1. The second template agent, the second inorganic silicon source, and the third solvent are mixed at 30-50°C for 0.5-3.0 hours. The resulting third mixed product is subjected to a first hydrothermal treatment and a second hydrothermal treatment in sequence to obtain a fourth mixed product. The conditions for the first hydrothermal treatment are: temperature 80-150°C and time 1-6 hours; the conditions for the second hydrothermal treatment are: temperature 160-180°C and time 4-60 hours.

[0026] S2. Mix the second alkali metal hydroxide (calculated as alkali metal oxide), the fourth solvent, and the second aluminum source (calculated as Al2O3) in a molar ratio of (1.5-5):(60-350):1 at 20-80°C for 0.5-2.0 hours to obtain the fifth mixed product.

[0027] S3. Mix the fourth mixed product and the fifth mixed product, subject the resulting mixture to a third hydrothermal treatment, remove the resulting solid and subject it to a fourth calcination to obtain a fourth solid product;

[0028] S4. The fourth solid product is mixed with the third alkaline solution, and the temperature is increased to the reaction temperature at a rate of 1-5℃ / min. The mixture is then reacted at the reaction temperature for 10-90 min to obtain the fifth solid product. The reaction temperature is 60-90℃, and the alkaline content in the third alkaline solution is 0.45-2 mol / L.

[0029] S5. The fifth solid product is subjected to a second ammonium exchange, and optionally a seventh calcination is performed to obtain the sixth solid product.

[0030] S6. The sixth solid product is mixed with the fourth solution containing a phosphorus source, and the resulting second slurry is subjected to a third drying and a fifth calcination.

[0031] Optionally, the first organosilicon source is selected from one or more of methyl orthosilicate and tetraethyl orthosilicate;

[0032] The second inorganic silicon source is selected from one or more of silica sol, water glass, and solid silica gel;

[0033] The first template agent and the second template agent are each independently selected from one or more of tetrapropylammonium bromide, tetrapropylammonium hydroxide, n-butylamine and hexamethylenediamine;

[0034] The first aluminum source and the second aluminum source are each independently selected from one or more of sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum isopropoxide and aluminum sol;

[0035] The first alkali metal hydroxide and the second alkali metal hydroxide are each independently selected from one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide;

[0036] The first alkaline solution and the third alkaline solution are each independently selected from one or more of sodium hydroxide solution, potassium hydroxide solution, lithium hydroxide solution and barium hydroxide solution;

[0037] The phosphorus source is selected from one or more of phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and ammonium phosphate.

[0038] Optionally, the molar ratio of the total amount of the first template agent, the first solvent, and the second solvent, the first alkali metal hydroxide, to the amount of the first organosilicon source is (0.06-0.55):(10-100):(0.02-1.5):1; the molar ratio of the first organosilicon source to the first aluminum source is (20-500):1; wherein the first organosilicon source is calculated as SiO2, the first alkali metal hydroxide is calculated as alkali metal oxide, and the first aluminum source is calculated as Al2O3;

[0039] Preferably, in step (2), the molar ratio of the first alkali metal hydroxide (calculated as alkali metal oxide), the second solvent, and the first aluminum source (calculated as Al2O3) is (2-4.5):(80-350):1;

[0040] Preferably, in step (4), the molar ratio of the first solid product to the first alkaline solution is 1:(2-10), the first solid product is calculated as SiO2, and the first alkaline solution is calculated as alkali metal oxide; the ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio of the first solid product is 1.2-5.0.

[0041] Preferably, in step (6), the weight ratio of the second solution containing the phosphorus source to the third solid product is 1:(0.5-2.0);

[0042] The total amount of the second template agent, the third solvent, and the fourth solvent, and the molar ratio of the amount of the second alkali metal hydroxide and the second inorganic silicon source are (0.06-0.55):(10-100):(0.02-1.5):1, and the molar ratio of the second inorganic silicon source to the second aluminum source is (20-500):1; wherein the second inorganic silicon source is calculated as SiO2, the second alkali metal hydroxide is calculated as alkali metal oxide, and the second aluminum source is calculated as Al2O3;

[0043] Preferably, in step S2, the molar ratio of the second alkali metal hydroxide (calculated as alkali metal oxide), the fourth solvent, and the second aluminum source (calculated as Al2O3) is (2-4.5):(80-350):1;

[0044] Preferably, in step S4, the molar ratio of the fourth solid product to the alkali-containing third solution is 1:(2-10), the fourth solid product is calculated as SiO2, the alkali-containing third solution is calculated as alkali metal oxide, and the ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio of the fourth solid product is 1.2-5.0.

[0045] Preferably, in step S6, the weight ratio of the fourth solution containing the phosphorus source to the sixth solid product is 1:(0.5-2.0).

[0046] Optionally, the conditions for dynamic crystallization include: a temperature of 160-180°C and a time of 12-60 hours;

[0047] The conditions for the third hydrothermal treatment include: a temperature of 160-180℃ and a time of 12-60 hours;

[0048] The conditions for the second, third, fourth, and fifth calcinations each independently include: a temperature of 400-600℃ and a time of 2-6 hours;

[0049] The conditions for the second drying and the third drying each independently include: a temperature of 90-120°C and a time of 2-24 hours.

[0050] Optionally, the method further includes: mixing catalyst particles obtained from the first drying and optionally the first calcination, ammonium salt and a fifth solvent in a weight ratio of 1:(0.1-1):(5-15) for a third ammonium exchange, and optionally washing;

[0051] The conditions for the third ammonium exchange include: a temperature of 50-100℃ and a time of 0.5-2 hours;

[0052] The ammonium salt is selected from one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate.

[0053] A third aspect of this disclosure provides the application of the composite catalyst described in the first aspect of this disclosure in increasing the production of low-carbon olefins in hydrocracking of LCO or heavy oil catalytic cracking.

[0054] Through the above technical solution, this disclosure uses a combination of phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve and a second molecular sieve as the main active component of the catalyst, which makes the catalyst have better accessibility of active centers and diffusion performance of reaction molecules. When used in hydrogenation LCO catalytic cracking or heavy oil catalytic cracking, it can effectively improve the yield of low carbon olefins.

[0055] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0056] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0057] Figure 1 This is a SEM image of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve prepared in Example 1 of this disclosure;

[0058] Figure 2 This is a SEM image of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve prepared in Example 2 of this disclosure;

[0059] Figure 3 These are SEM images of the second molecular sieve (a β molecular sieve with a pore size of 0.59 nm) in Examples 4-6 of this disclosure;

[0060] Figure 4 These are SEM images of the second molecular sieve (Y-type molecular sieve) in Examples 7-9 of this disclosure. Detailed Implementation

[0061] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0062] In a first aspect, this disclosure provides a composite catalyst comprising a phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve, a second molecular sieve, and a support. Based on the dry weight of the composite catalyst, the content of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 5-35% by weight, the content of the second molecular sieve is 10-50% by weight, and the content of the support is 30-80% by weight. The phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve has a closed hollow structure, an average grain size of 0.2-3.0 μm, and a bulk silicon-aluminum molar ratio to surface silicon-aluminum molar ratio of 1.0-1.5. The phosphorus-aluminum molar ratio of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 0.1-1.5. The total specific surface area of ​​the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 340-400 m². 2 / g, mesoporous specific surface area is 40-150m² 2 / g, wherein the mesoporous specific surface area accounts for 15-40% of the total specific surface area; the strong Brønsted acid content of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve accounts for 65-80% of the total Brønsted acid content, and the strong Lewis acid content accounts for 50-75% of the total Lewis acid content; the second molecular sieve is a molecular sieve with a pore size of 0.56-0.75nm, or the second molecular sieve is a rare earth-containing Y-type molecular sieve.

[0063] The composite catalyst disclosed herein contains a phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve. Its hierarchical porous structure gives the catalyst better accessibility of active centers and diffusion performance for reactant molecules, and can reduce the secondary conversion of low-carbon olefins. When combined with a second molecular sieve, its application in hydrogenation LCO catalytic cracking or heavy oil catalytic cracking can effectively improve the yield of low-carbon olefins.

[0064] In one specific embodiment of this disclosure, the phosphorus-aluminum molar ratio of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 0.2-1.3. In this disclosure, the phosphorus-aluminum molar ratio of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is determined by XRF fluorescence method.

[0065] In one specific embodiment of this disclosure, the average grain size of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve crystals is 0.4-2.5 μm, preferably 0.6-2.5 μm. The ratio of the bulk silicon-aluminum molar ratio (as SiO2 / Al2O3) to the surface silicon-aluminum molar ratio (as SiO2 / Al2O3) is 1.1-1.4, and the relative crystallinity is 75-90%. In this disclosure, grain size refers to the size of the widest part of the grain, which can be obtained by measuring the size of the widest part of the grain projection plane in the SEM or TEM image of the sample. The average grain size is obtained by selecting any 10 molecular sieves in the SEM or TEM image and calculating their average value. The bulk silicon-aluminum molar ratio refers to the overall silicon-aluminum molar ratio of the ZSM-5 nanocrystalline material, which is determined by the XRF method. The surface silicon-aluminum molar ratio is determined by the XPS method. The specific testing methods are well known to those skilled in the art and will not be described in detail here. The bulk silicon-aluminum molar ratio is 15-200. In this disclosure, the relative crystallinity of the molecular sieve is based on the XRD standard ZSM-5 molecular sieve standard from the China Petroleum and Chemical Research Institute, and the crystallinity of the standard is considered to be 100%.

[0066] In one specific embodiment of this disclosure, the total specific surface area of ​​the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve before phosphorus modification is 350-400 m². 2 / g, mesoporous specific surface area is 45-140m² 2 / g, wherein the mesoporous specific surface area accounts for 20-35% of the total specific surface area, and the N2 adsorption-desorption curve exhibits an H4-type hysteresis loop. In this disclosure, the total specific surface area and mesoporous specific surface area are obtained using BET analysis.

[0067] In one specific embodiment of this disclosure, the proportion of the strong Brønsted acid to the total Brønsted acid is 70-80%, and the proportion of the strong Leucine to the total Leucine is 55-70%. The strong Brønsted acid and the total Brønsted acid are prepared using a pyridine infrared acidic method, and the strong Leucine and the total Leucine are prepared using a pyridine infrared acidic method.

[0068] According to this disclosure, the molecular sieve with an aperture size of 0.56-0.75 nm can be one or more of the molecular sieves having structures of AET, AFR, AFS, AFI, BEA, BOG, CFI, CON, GME, IFR, ISV, LTL, MEI, MOR, OFF, and SAO; preferably at least one of Beta, SAPO-5, SAPO-40, SSZ-13, CIT-1, ITQ-7, ZSM-18, mordenite, and sodium chalcogenide.

[0069] According to this disclosure, the Y-type molecular sieve can be a hydrothermally or gas-phase stabilized Y-type molecular sieve. The rare earth content of the Y-type molecular sieve, calculated as rare earth element oxides (RE2O3), is 2-25% by weight, and the rare earth element can be lanthanum and / or cerium; the Y-type molecular sieve may contain phosphorus or not, specifically, the phosphorus content of the Y-type molecular sieve, calculated as P2O5, is 0-10% by weight; the Y-type molecular sieve can be selected from one or more of REY molecular sieves, DASY molecular sieves, USY molecular sieves, phosphorus-containing DASY molecular sieves, phosphorus-containing USY molecular sieves, PSRY molecular sieves, HRY molecular sieves, HSY molecular sieves, SCY molecular sieves, and RSCY molecular sieves.

[0070] According to this disclosure, the carrier is selected from one or more of natural clay, alumina carrier, silica carrier, aluminum phosphate carrier, and aluminosilicate carrier. In one embodiment, the silica carrier is one or more of neutral silica sol, acidic silica sol, or alkaline silica sol; the alumina carrier is one or more of alumina sol, acidified boehmite, hydrated alumina, and activated alumina; the aluminum phosphate carrier is aluminum phosphate gel; and the aluminosilicate carrier is selected from one or more of solid aluminosilicate materials, aluminosilicate sol, and aluminosilicate gel.

[0071] In one specific embodiment of this disclosure, the support comprises a silica support; based on the dry weight of the composite catalyst, the silica support has a SiO2 content of 1-20% by weight.

[0072] In one specific embodiment of this disclosure, based on the dry weight of the composite catalyst, the composite catalyst contains 20-35 wt% phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve, 10-20 wt% molecular sieve with a pore size of 0.56-0.75 nm, 20-60 wt% (e.g., 25-50 wt%) clay, 5-35 wt% (e.g., 10-30 wt%) acidified pseudoboehmite, 3-25 wt% (e.g., 5-15 wt%) or 3-20 wt% alumina sol, and 0-15 wt% (e.g., 3-10 wt%) or 5-15 wt% silica sol.

[0073] In one specific embodiment of this disclosure, based on the dry weight of the catalyst, the composite catalyst contains 5-20 wt% phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve, 15-50 wt% rare earth-containing Y-type molecular sieve, 20-60 wt% (e.g., 25-50 wt%) clay, 5-35 wt% (e.g., 10-30 wt%) acidified pseudoboehmite, 3-25 wt% (e.g., 5-15 wt%) or 3-20 wt% alumina sol, and 0-15 wt% (e.g., 3-10 wt%) or 5-15 wt% silica sol.

[0074] In one specific embodiment of this disclosure, based on the dry weight of the composite catalyst, the sodium oxide content in the composite catalyst is preferably less than 0.15% by weight.

[0075] The second aspect of this disclosure provides a method for preparing the composite catalyst provided in the first aspect of this disclosure, the method comprising: subjecting a slurry containing a support, a phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve, a second molecular sieve and water to a first drying and optionally a first calcination.

[0076] This disclosure does not limit the specific form of the first drying, which can be conventionally used by those skilled in the art. In a preferred embodiment, the first drying is spray drying, which can dry the material while also shaping the catalyst. Spray drying is well known to those skilled in the art, and specific methods will not be described in detail here.

[0077] In one specific embodiment of this disclosure, the preparation steps of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve include: (1) mixing and stirring a first organosilicon source and a first solvent at 30-50°C for 0.5-5 hours, then heating to 70-100°C and mixing and stirring for 2-10 hours, and mixing the resulting mixed liquid with a first template agent at 20-30°C for 0.5-3.0 hours to obtain a first mixed product; (2) mixing a first alkali metal hydroxide (calculated as alkali metal oxide), a second solvent, and a first aluminum source (calculated as Al2O3) in a molar ratio of (1.5-5):(60-350):1 at 20-80°C for 0.5-2.0 hours to obtain a second mixed product; (3) mixing the first... The mixed product is mixed with the second mixed product and then subjected to dynamic crystallization. The obtained solid is taken out and subjected to a second calcination to obtain the first solid product; (4) The first solid product is mixed with the first solution containing alkali and heated to the reaction temperature at a heating rate of 1-5℃ / min. The reaction is carried out at the reaction temperature for 10-90min to obtain the second solid product; wherein the reaction temperature is 60-90℃ and the alkali content in the first solution containing alkali is 0.45-2mol / L; (5) The second solid product is subjected to the first ammonium exchange to obtain the third solid product; (6) The third solid product is mixed with the second solution containing phosphorus source and the obtained first slurry is subjected to the second drying and the third calcination.

[0078] According to this disclosure, the total amount of the first template agent, the first solvent, and the second solvent, and the molar ratio of the first alkali metal hydroxide and the first organosilicon source to the total amount can vary within a wide range, for example, it can be (0.06-0.55):(10-100):(0.02-1.5):1, preferably (0.08-0.50):(15-85):(0.03-1.2):1, and the molar ratio of the first organosilicon source to the first aluminum source can be (20-500):1, preferably (23-200):1; wherein, the first organosilicon source is calculated as SiO2, the first alkali metal hydroxide is calculated as an alkali metal oxide (for example, when the first alkali metal hydroxide is NaOH, the first alkali metal hydroxide is calculated as Na2O), and the first aluminum source is calculated as Al2O3. In one embodiment, the first template agent and the first alkali metal hydroxide contain OH. - The ratio of the total molar amount to the molar amount of the first organosilicon source, calculated as SiO2, is (0.01-1.5):1, preferably (0.02-1.2):1.

[0079] According to this disclosure, in step (2), the molar ratio of the first alkali metal hydroxide (calculated as alkali metal oxide), the second solvent, and the first aluminum source (calculated as Al2O3) is preferably (2.0-4.5):(80-350):1.

[0080] According to this disclosure, in step (3), dynamic crystallization is well known to those skilled in the art, and the conditions for dynamic crystallization may include: a temperature of 80-200°C and a time of 4-80 hours; preferably, a temperature of 160-180°C and a time of 12-60 hours.

[0081] According to this disclosure, in step (4), the weight ratio of the first solid product to the amount of the first alkali-containing solution can be 1:(2-10); the ratio of the bulk silicon-aluminum molar ratio and the surface silicon-aluminum molar ratio of the first solid product is 1.2-5.0.

[0082] According to this disclosure, in step (5), the first ammonium exchange of the second solid product includes: mixing the second solid product, the first ammonium source, and the fifth solvent in a weight ratio of 1:(0.5-2.0):(5-20), and reacting the resulting mixture at 50-100°C, preferably 60-90°C, for 0.5-2 hours. The first ammonium source is selected from one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate. The ammonium exchange can be performed once or multiple times. Optionally, the product obtained from the first ammonium exchange is filtered, washed, and dried; alternatively, the product obtained from the first ammonium exchange is subjected to a sixth calcination; preferably, the product obtained from the first ammonium exchange is filtered, washed, and dried before undergoing a sixth calcination; the temperature of the sixth calcination can be 400-600°C, and the time can be 1-24 hours, preferably 1-10 hours or 1.5-6 hours, more preferably, the temperature is 450-580°C, and the time is 2-4.5 hours.

[0083] According to this disclosure, in step (6), the weight ratio of the second solution containing the phosphorus source to the third solid product can be 1:(0.5-2.0). The mass content of the phosphorus source in the second solution is, for example, 1-10%.

[0084] According to this disclosure, compared with the first solid product, the hollow ZSM-5 multi-level porous molecular sieve (third solid product) has a mesopore specific surface area increased by 100-500%, a mesopore volume increased by 150-600%, and a total acid content increased by 50-250%.

[0085] In another specific embodiment of this disclosure, the preparation steps of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve include: S1, mixing the second template agent, the second inorganic silicon source, and the third solvent at 30-50°C for 0.5-3.0 hours, and subjecting the obtained third mixed product to a first hydrothermal treatment and a second hydrothermal treatment in sequence to obtain a fourth mixed product; wherein, the conditions for the first hydrothermal treatment include: a temperature of 80-150°C and a time of 1-6 hours; the conditions for the second hydrothermal treatment include: a temperature of 160-180°C and a time of 4-60 hours; S2, mixing the second alkali metal hydroxide (calculated as alkali metal oxide), the fourth solvent, and the second aluminum source (calculated as Al2O3) in a molar ratio of (1.5-5):(60-350):1 at 20-80°C for 0.5-2 hours. S3. After 0 hours, a fifth mixed product is obtained; S4. The fourth mixed product and the fifth mixed product are mixed, and the resulting mixture is subjected to a third hydrothermal treatment. The resulting solid is taken out and subjected to a fourth calcination to obtain a fourth solid product; S5. The fourth solid product is mixed with a third solution containing alkali, and the temperature is raised to the reaction temperature at a heating rate of 1-5℃ / min. The reaction is carried out at the reaction temperature for 10-90 min to obtain a fifth solid product; wherein the reaction temperature is 60-90℃, and the alkali content in the third solution containing alkali is 0.45-2 mol / L; S6. The fifth solid product is subjected to a second ammonium exchange to obtain a sixth solid product; S7. The sixth solid product is mixed with a fourth solution containing a phosphorus source, and the resulting second slurry is subjected to a third drying and a fifth calcination.

[0086] According to this disclosure, the total amount of the second template agent, the third solvent, and the fourth solvent, and the molar ratio of the second alkali metal hydroxide to the second inorganic silicon source can vary within a wide range, for example, it can be (0.06-0.55):(10-100):(0.02-1.5):1, preferably (0.08-0.50):(15-85):(0.03-1.2):1, and the molar ratio of the second inorganic silicon source to the second aluminum source can be (20-500):1; wherein, the second inorganic silicon source is calculated as SiO2, the second alkali metal hydroxide is calculated as an alkali metal oxide (for example, when the second alkali metal hydroxide is NaOH, the second alkali metal hydroxide is calculated as Na2O), and the second aluminum source is calculated as Al2O3. In one embodiment, the second template agent and the second alkali metal hydroxide contain OH. - The ratio of the total molar amount to the molar amount of the second inorganic silicon source in terms of SiO2 (abbreviated as OH / SiO2) is (0.01-1.5):1, preferably (0.02-1.2):1.

[0087] According to this disclosure, hydrothermal treatment is well known to those skilled in the art and can be carried out, for example, in a heat-resistant, sealed container. This disclosure does not limit the pressure of the hydrothermal treatment; it can be carried out under the autogenous pressure of the reaction system or under an applied pressure, preferably under autogenous pressure.

[0088] According to this disclosure, in step S2, the molar ratio of the second alkali metal hydroxide (calculated as alkali metal oxide), the fourth solvent, and the second aluminum source (calculated as Al2O3) is preferably (2.0-4.5):(80-350):1.

[0089] In one embodiment, the conditions for the third hydrothermal treatment include: a temperature of 160-180°C and a time of 12-60 hours.

[0090] According to this disclosure, in step S4, the weight ratio of the fourth solid product to the third alkali-containing solution can be 1:(2-10), and the ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio of the fourth solid product is 1.2-5.0.

[0091] According to this disclosure, in step S5, the second ammonium exchange of the fifth solid product includes: mixing the fifth solid product, the second ammonium source, and the sixth solvent in a weight ratio of 1:(0.5-2):(5-20), and reacting the resulting mixture at 50-100°C, preferably 60-90°C, for 0.5-2 hours. The second ammonium source is selected from one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate. The ammonium exchange can be performed once or multiple times. Optionally, the product obtained from the second ammonium exchange is filtered, washed, and dried; alternatively, the product obtained from the second ammonium exchange is subjected to a seventh calcination; preferably, the product obtained from the second ammonium exchange is filtered, washed, and dried before undergoing a seventh calcination; the temperature of the seventh calcination can be 400-600°C, and the time can be 1-24 hours, preferably 1-10 hours or 1.5-6 hours, more preferably, the temperature is 450-580°C, and the time is 2-4.5 hours.

[0092] According to this disclosure, in step S6, the weight ratio of the fourth solution containing the phosphorus source to the sixth solid product can be 1:(0.5-2.0). The mass content of the phosphorus source in the fourth solution is, for example, 1-10%.

[0093] According to this disclosure, compared with the fourth solid product, the hollow ZSM-5 multi-level porous molecular sieve (sixth solid product) has a mesopore specific surface area increased by 100-500%, a mesopore volume increased by 150-600%, and a total acid content increased by 50-250%.

[0094] According to this disclosure, roasting is a technical means conventionally used by those skilled in the art, and roasting can be carried out in a muffle furnace, tube furnace, etc. The conditions for the second, third, fourth, and fifth roastings each independently include: a temperature of 400-600°C and a time of 2-6 hours, preferably, a temperature of 450-580°C and a time of 2.5-4.5 hours.

[0095] According to this disclosure, drying is a technique conventionally employed by those skilled in the art, and calcination can be carried out in a constant temperature drying oven. The conditions for the second drying and the third drying each independently include: a temperature of 90-120°C and a time of 2-24 hours.

[0096] According to this disclosure, the first organosilicon source is selected from one or more of methyl orthosilicate and tetraethyl orthosilicate; the second inorganic silicon source is selected from one or more of silica sol, water glass, and solid silica gel; the first template agent and the second template agent are each independently selected from one or more of tetrapropylammonium bromide, tetrapropylammonium hydroxide, n-butylamine, and hexamethylenediamine; the first aluminum source and the second aluminum source are each independently selected from one or more of sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum isopropoxide, and aluminum sol; the first alkali metal hydroxide and the second alkali metal hydroxide are each independently selected from one or more of lithium hydroxide, sodium hydroxide, and potassium hydroxide; the first alkaline solution and the second alkaline solution are each independently selected from one or more of sodium hydroxide solution, potassium hydroxide solution, lithium hydroxide, and barium hydroxide; and the phosphorus source is selected from at least one or more of phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and ammonium phosphate.

[0097] In one specific embodiment of this disclosure, the method further includes: mixing catalyst particles obtained from the first drying and optionally the first calcination, ammonium salt, and a fifth solvent in a weight ratio of 1:(0.1-1):(5-15) and then performing a third ammonium exchange, and optionally washing; the conditions for the third ammonium exchange include: a temperature of 50-100°C and a time of 0.5-2 hours; the solution containing ammonium salt is calculated as ammonium salt, and the ammonium salt is selected from one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate. The ammonium exchange can be performed multiple times.

[0098] According to this disclosure, in one embodiment, the first solvent, the second solvent, the third solvent, the fourth solvent, the fifth solvent, and the sixth solvent are each water.

[0099] This disclosure provides a third aspect of the application of the composite catalyst provided in the first aspect of this disclosure in increasing the production of low-carbon olefins in hydrocracking of LCO or heavy oil catalytic cracking. Specifically, when the second molecular sieve is a molecular sieve with a pore size of 0.56-0.75 nm, the composite catalyst is beneficial for increasing the production of low-carbon olefins in hydrocracking of LCO; when the second molecular sieve is a rare-earth-containing Y-type molecular sieve, the composite catalyst is beneficial for increasing the production of low-carbon olefins in heavy oil catalytic cracking.

[0100] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0101] Unless otherwise specified, all raw materials used in the following examples and comparative examples were commercially available. Kaolin was an industrial product of China Kaolin Corporation, with a solid content of 75% by weight; boehmite was produced by Shandong Aluminum Plant, with an alumina content of 65% by weight; alumina sol was produced by Qilu Branch of Sinopec Catalyst Co., Ltd., with an alumina content of 21% by weight; silica sol was produced by Beijing Chemical Plant, with a silica content of 25% by weight (acidic silica sol, pH 3.0); concentrated hydrochloric acid was chemically pure and produced by Beijing Chemical Plant. β-molecular sieve, grade BETA-25-NKC, with a pore size of 0.59 nm, was produced by Tianjin Nanhua Catalyst Co., Ltd., and its SEM image is shown below. Figure 3 As shown. Y-type molecular sieve, grade SCY-12, rare earth content 12% by weight, produced by Qilu Branch of Sinopec Catalyst Co., Ltd., its SEM image is shown below. Figure 4 As shown.

[0102] In the examples and comparative examples, the crystal size of the molecular sieve was measured by SEM. Ten crystal sizes were randomly measured, and the average value was taken to obtain the average crystal size of the molecular sieve sample.

[0103] The bulk silica-alumina ratio of the samples was determined by XRF using a ZSX Primus II (Rigaku) ​​X-ray fluorescence spectrometer. Test conditions included an excitation voltage of 50 kV, an excitation current of 50 mA, and rhodium and palladium. The elemental composition of the molecular sieve was analyzed by measuring the peak intensity of each element using a scintillation counter and a proportional counter.

[0104] The surface silicon-to-aluminum molar ratio of the samples was determined by XPS using a Thermo Fisher ESCALab 250 X-ray photoelectron spectrometer. The testing conditions were: monochromatic Al Kα X-rays as the excitation source, excitation energy 1496.6 eV, and power 150 W. The electron binding energy was corrected using the C1s peak (284.8 eV) of the contaminating carbon.

[0105] The total specific surface area, mesoporous specific surface area, and N2 adsorption-desorption curves of the samples were determined using the BET adsorption-desorption total analysis method. Instrument: Micromeritics ASAP 2420 adsorption analyzer (USA). Test conditions: The samples were degassed under vacuum at 100℃ and 300℃ for 0.5 h and 6 h, respectively, and then N2 adsorption-desorption tests were conducted at 77.4 K. The adsorption and desorption amounts of nitrogen in the purified samples under different specific pressures were measured, and N2 adsorption-desorption isotherms were obtained. The BET specific surface area was calculated using the BET formula, the micropore area was calculated using t-plot, and the pore size distribution was calculated using the BJH method.

[0106] The relative crystallinity of the samples was determined by X-ray diffraction. Instrument: Empyrean. Test conditions: tube voltage 40kV, tube current 40mA, Cu target Kα radiation, 2θ scan range 5°-35°, scan rate 2 (°) / min.

[0107] The phosphorus-aluminum molar ratio of the sample was determined using X-ray fluorescence spectrometry. Instrument: ZSX Primus II (Rigaku) ​​X-ray fluorescence spectrometer. Test conditions: excitation voltage 50 kV, excitation current 50 mA, rhodium-palladium. The intensity of each elemental peak was determined using a scintillation counter and a proportional counter to analyze the elemental composition of the molecular sieve.

[0108] The amounts of strong Brønsted acid and total Brønsted acid in the samples were determined using pyridine infrared adsorption. The amounts of strong Lewis acid and total Lewis acid were also determined using the same method. Instrument: NICOLET 6700 Fourier transform infrared spectrometer (BIQ-RAD, USA). Test method: The samples were compressed into pellets and sealed in the in-situ cell of the infrared spectrometer. Adsorption and desorption were performed according to the set program. The amount of pyridine-adsorbed acid was calculated based on the peak area.

[0109] Examples 1-3 are examples of preparing phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieves.

[0110] Example 1

[0111] (1) Weigh 456.0 g of tetraethyl orthosilicate, add 3115.7 g of deionized water, stir and heat in a water bath at 40°C for 2 h, then raise the water bath temperature to 70°C and stir and heat for 4 h to remove the ethanol produced by the hydrolysis of the silicon source. During this process, water that evaporates at the same time as the ethanol is intermittently added to the system. The resulting mixed liquid is mixed and stirred with 558.3 ​​g of tetrapropylammonium hydroxide aqueous solution (mass fraction of 25.0%) at 25°C for 1 h to obtain the first mixed product.

[0112] (2) Weigh 17.2 g of sodium hydroxide granules, add 384.0 g of deionized water to completely dissolve the sodium hydroxide, then add 40.8 g of aluminum nitrate nonahydrate, stir at room temperature for 1.0 h to obtain the second mixed product (i.e. aluminum source solution);

[0113] (3) The second mixed product is slowly added to the first mixed product and mixed evenly. The mixture is stirred at room temperature for 4.0 h. The resulting precursor liquid is transferred to the synthesis vessel and dynamically crystallized at 170 °C for 48 h. After crystallization, the product is centrifuged, filtered, washed, dried, and calcined at 550 °C for 4 h to obtain the first solid product (denoted as molecular sieve I-M1).

[0114] (4) Mix the first solid product with a sodium hydroxide solution with a concentration of 0.5 mol / L. The mass ratio of the first solid product to the alkaline solution is 1:10. Heat the solution to 80°C at a heating rate of 2°C / min and stir it at that temperature for 30 min. Filter, wash and dry to obtain the second solid product (denoted as molecular sieve I-S1-Na).

[0115] (5) Mix the second solid product, ammonium chloride, and deionized water at a weight ratio of 1:1:10, stir and heat in an 80°C water bath for 30 min, filter, wash, and dry. Mix the obtained solid product, ammonium chloride, and deionized water at a weight ratio of 1:0.5:10, perform a second ammonium exchange, filter, wash, dry, and calcine at 550°C for 2 h to obtain the third solid product (a hydrogen-type hollow ZSM-5 multi-level porous molecular sieve, denoted as I-S1-H).

[0116] (6) Dissolve 2.69 g of H3PO4 solution (concentration 85% by weight) in 46.25 g of deionized water, stir until fully dissolved, to obtain a phosphorus-containing solution; spread 50 g of the third solid product in a petri dish, slowly add the phosphorus-containing solution dropwise, mix thoroughly until the molecular sieve becomes a "viscous paste", dry in air at 115℃ for 4 h, and then calcine at 550℃ for 2 h to obtain a phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve, denoted as SS-1, and its SEM image is shown below. Figure 1 As shown, the properties of the samples are listed in Table 1.

[0117] Example 2

[0118] (1) Weigh 550.0 g of methyl orthosilicate, add 2975.0 g of deionized water, stir and heat in a water bath at 30°C for 5 h, then raise the water bath temperature to 70°C and stir for 4 h to remove the ethanol produced by the hydrolysis of the silicon source. During this process, water that evaporates at the same time as the ethanol is intermittently added to the system. The resulting mixed liquid is mixed and stirred with 241.5 g of tetrapropylammonium bromide aqueous solution (mass fraction of 25.0%) at 20°C for 0.5 h to obtain the first mixed product.

[0119] (2) Weigh 9.1 g of sodium hydroxide granules, add 217.0 g of deionized water to completely dissolve the sodium hydroxide, then add 6.0 g of sodium aluminate (alumina content is 62.0%), stir at 20°C for 2.0 h to obtain the second mixed product;

[0120] (3) The second mixed product is slowly added to the first mixed product and mixed evenly. Stirred at room temperature for 4.0 h. The resulting precursor liquid is transferred to the synthesis vessel and dynamically crystallized at 180 °C for 24 h. After crystallization, it is centrifuged, filtered, washed, dried, and calcined at 550 °C for 4 h to obtain the first solid product (denoted as molecular sieve I-M2).

[0121] (4) Mix the first solid product and a sodium hydroxide alkaline solution with a concentration of 0.6 mol / L evenly. The mass ratio of the first solid product to the alkaline solution is 1:10. Heat the product to 80°C at a heating rate of 4°C / min, and then heat and stir at 80°C for 30 min. Filter, wash and dry to obtain the second solid product (denoted as molecular sieve I-S2-Na).

[0122] (5) The second solid product: ammonium chloride: deionized water were mixed evenly in a weight ratio of 1:1:10. The mixture was stirred and heated in an 80°C water bath for 30 min. After filtration, washing and drying, the resulting solid product: ammonium chloride: deionized water were mixed evenly in a weight ratio of 1:0.5:10. The mixture was subjected to a second ammonium exchange, filtered, washed and dried, and calcined at 550°C for 2 h to obtain the third solid product (hydrogen-type hollow ZSM-5 multi-level porous molecular sieve, denoted as I-S2-H).

[0123] (6) Dissolve 2.68g of ammonium dihydrogen phosphate in 44.21g of deionized water until fully dissolved and stirred until homogeneous to obtain a phosphorus-containing solution; spread 50g of the third solid product in a petri dish, slowly add the prepared phosphorus-containing solution dropwise, and mix thoroughly until the molecular sieve becomes a "viscous paste"; dry in air at 110℃ for 4h, and calcine at 550℃ for 2h to obtain a phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve, designated as SS-2, and its SEM image is shown below. Figure 2 As shown, the properties of the samples are listed in Table 1.

[0124] Example 3

[0125] (1) Weigh 455.9 g of tetrapropylammonium hydroxide aqueous solution (mass fraction of 25.0%), add 3238.3 g of deionized water, stir at room temperature for 10 min, then add 1156.4 g of silica sol (SiO2 content of 25%), stir at 50℃ water bath for 1.0 h, transfer the obtained third mixed product into the reaction vessel, crystallize at 80℃ for 2 h, then raise the temperature to 170℃ and crystallize for 12 h to obtain the fourth mixed product;

[0126] (2) Weigh 9.7 g of sodium hydroxide granules, add 277.9 g of deionized water to completely dissolve the sodium hydroxide, then add 33.3 g of aluminum nitrate nonahydrate, stir at 25°C for 1.0 h to obtain the fifth mixed product;

[0127] (3) Add the fourth mixed product to the fifth mixed product, stir evenly, and continue to crystallize at 170℃ for 36h; after crystallization, centrifuge and filter, wash, dry, and calcine at 550℃ for 4h to obtain the fourth solid product (denoted as molecular sieve I-M3).

[0128] (4) Mix the fourth solid product with a sodium hydroxide solution with a concentration of 1.0 mol / L. The mass ratio of the fourth solid product to the alkaline solution is 1:10. Heat the solution to 80°C at a heating rate of 5°C / min and stir it at that temperature for 30 min. Filter, wash and dry to obtain the fifth solid product (denoted as molecular sieve I-S3-Na).

[0129] (5) Mix the fifth solid product, ammonium chloride, and deionized water in a weight ratio of 1:1:10. Stir and heat in an 80°C water bath for 30 min. Filter, wash, and dry. Then mix the obtained solid product, ammonium chloride, and deionized water in a weight ratio of 1:0.5:10. Perform a second ammonium exchange, filter, wash, and dry. Calcine at 550°C for 2 h to obtain the sixth solid product (denoted as I-S3-H).

[0130] (6) Dissolve 1.71g of H3PO4 solution (concentration 85% by weight) in 42.49g of deionized water, stir until fully dissolved, and obtain a phosphorus-containing solution; spread 50g of the sixth solid product in a petri dish, slowly add the prepared phosphorus-containing solution, mix thoroughly until the molecular sieve is in the form of a "viscous paste"; dry in air at 115℃ for 4h, and then calcine at 550℃ for 2h to obtain a phosphorus-containing hollow ZSM-5 multi-level porous molecular sieve, denoted as SS-3, and its properties are listed in Table 1.

[0131] Comparative Example 1

[0132] The conventional ZSM-5 molecular sieve DSS-1 was purchased from Sinopec Catalyst Company Qilu Branch, with a silicon-aluminum molar ratio (SiO2 / Al2O3) of 25. Its properties are listed in Table 1.

[0133] Table 1

[0134]

[0135]

[0136] In Table 1, R represents the template agent, and the ratio of bulk to surface silicon-aluminum molar ratio represents the ratio of bulk silicon-aluminum molar ratio to surface silicon-aluminum molar ratio.

[0137] Increase in mesoporous specific surface area = 100% × [Mesoporous specific surface area of ​​hollow ZSM-5 hierarchical molecular sieve (or hollow hierarchical ZSM-5 nanocrystalline material, hydrogen-type hollow ZSM-5 hierarchical molecular sieve before the introduction of phosphorus) / mesoporous specific surface area of ​​the first solid product (or the fourth solid product) - 1];

[0138] Mesoporous volume increase = 100% × [Mesoporous volume of hollow ZSM-5 hierarchical molecular sieve (or hollow hierarchical ZSM-5 nanocrystalline material, hydrogen-type hollow ZSM-5 hierarchical molecular sieve before the introduction of phosphorus) / mesoporous volume of the first solid product (or the fourth solid product) - 1];

[0139] Total acid content increase = 100% × [total acid content of hollow ZSM-5 hierarchical porous molecular sieve (or hollow hierarchical porous ZSM-5 nanocrystalline material, hydrogen-type hollow ZSM-5 hierarchical porous molecular sieve before the introduction of phosphorus) / total acid content of the first solid product (or the fourth solid product) - 1].

[0140] Examples 4-9 and Comparative Examples 2-5 are examples of preparing composite catalysts.

[0141] Examples 4-6

[0142] Catalysts were prepared using the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieves prepared in Examples 1-3, respectively, and the catalyst numbers are A1-A3.

[0143] Methods for preparing composite catalysts include:

[0144] (1) Mix boehmite and water evenly, and add concentrated hydrochloric acid with a concentration of 36% by weight while stirring. The acid-aluminum molar ratio is 0.2 (the weight ratio of HCl to boehmite calculated as Al2O3). The resulting mixture is aged at 70°C for 1.5 hours to obtain an aged boehmite slurry. The alumina content of the aged boehmite slurry is 12% by weight.

[0145] (2) The phosphorus-containing hollow ZSM-5 multi-level porous molecular sieve, β molecular sieve, alumina sol, silica sol, kaolin, and the above-prepared aged pseudoboehmite slurry and deionized water are mixed evenly to form a slurry with a solid content of 30% by weight, and spray-dried to obtain catalyst microspheres.

[0146] (3) The catalyst microspheres were calcined at 550℃ for 4 hours;

[0147] (4) The calcined catalyst microspheres were exchanged at 80°C for 1 hour according to the weight ratio of catalyst microspheres: ammonium salt: H2O = 1:1:10, filtered, and the above exchange and filtration process was repeated once. The catalyst was then dried. The ammonium salt was ammonium chloride, and the sodium oxide content in the obtained composite catalyst was less than 0.15% by weight. The composition of the prepared catalyst is shown in Table 2.

[0148] Comparative Example 2

[0149] Catalyst DA1 was prepared using the same method as in Example 4, except that molecular sieve DSS-1 from Comparative Example 1 was used instead of molecular sieve SS-1 prepared in Example 1. The composition of the prepared catalyst is shown in Table 2.

[0150] Comparative Example 3

[0151] Catalyst DA2 was prepared using the same method as in Example 4, except that phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve was not added. The composition of the prepared catalyst is shown in Table 2.

[0152] Examples 7-9

[0153] Catalysts were prepared using the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieves prepared in Examples 1-3, following the method of Example 4. The only difference was that the second molecular sieve in Examples 7-9 was a Y-type molecular sieve (SCY-12 molecular sieve), and the catalysts were numbered A4-A6 in sequence. The composition of the prepared catalysts is shown in Table 2.

[0154] Comparative Example 4

[0155] Catalyst DA3 was prepared using the same method as in Example 7, except that molecular sieve DSS-1 from Comparative Example 1 was used instead of molecular sieve SS-1 prepared in Example 1. The composition of the prepared catalyst is shown in Table 2.

[0156] Comparative Example 5

[0157] Catalyst DA4 was prepared using the same method as in Example 7, except that phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve was not added. The composition of the prepared catalyst is shown in Table 2.

[0158] Table 2

[0159]

[0160] Test Example 1

[0161] The composite catalysts prepared in Examples 4-6 and Comparative Examples 2-3 were aged at 820°C and 100% vol% steam for 30 hours. Their performance in the hydrogenation catalytic cracking of LCO was then evaluated in a small fixed fluidized bed reactor under the following conditions: reaction temperature 620°C and weight hourly space velocity (WHSV) 4 h⁻¹. -1 The agent-to-oil weight ratio was 12. The properties of hydrogenated LCO are shown in Table 3, and the reaction results are shown in Table 4. The product mass distribution was calculated based on the feedstock.

[0162] Table 3

[0163]

[0164]

[0165] Table 4

[0166] Example 4 Example 5 Example 6 Comparative Example 2 Comparative Example 3 catalyst A1 A2 A3 DA1 DA2 Dry gas, % by weight 14.37 14.34 13.02 6.81 2.54 Liquefied petroleum gas, % by weight 38.64 37.46 36.53 20.13 8.59 Gasoline, % by weight 26.30 26.80 27.91 38.49 15.63 Diesel fuel, % by weight 12.05 13.41 14.73 23.01 37.50 Heavy oil, % by weight 1.67 1.97 2.67 7.80 34.87 Coke, % by weight 6.97 6.02 5.14 3.76 0.87 Low carbon olefins, % by weight 39.79 39.22 37.47 19.9 6.11 Ethylene, % by weight 9.64 9.13 8.97 4.38 1.01 Propylene, % by weight 19.46 19.67 18.63 10.05 2.67 Butene, % by weight 10.69 10.42 9.87 5.47 2.43

[0167] As shown in Table 4, the composite catalyst provided in this disclosure has better hydrogenation LCO catalytic cracking ability and higher low-carbon olefin yield.

[0168] Test Example 2

[0169] The composite catalysts prepared in Examples 7-9 and Comparative Examples 4-5 were aged at 820°C and 100% (v / v) water vapor for 30 hours. Their heavy oil catalytic cracking performance was then evaluated in a small fixed fluidized bed reactor under the following conditions: reaction temperature 520°C and catalyst-to-oil weight ratio 10. The heavy oil properties are shown in Table 5, and the reaction results are shown in Table 6. The product mass distribution was calculated based on the feedstock.

[0170] Table 5

[0171]

[0172]

[0173] Table 6

[0174] Example 7 Example 8 Example 9 Comparative Example 4 Comparative Example 5 catalyst A4 A5 A6 DA3 DA4 Dry gas, % by weight 8.6 8.4 8.27 5.18 3.69 Liquefied petroleum gas, % by weight 38.47 37.67 36.49 33 28.42 Gasoline, % by weight 36.52 36.84 35.53 33.67 42.62 Diesel fuel, % by weight 7.75 7.18 6.87 16.07 14.28 Heavy oil, % by weight 3.58 4.05 5.97 8.02 7.11 Coke, % by weight 5.08 5.86 6.87 4.06 3.88 Ethylene, % by weight 4.01 3.84 3.65 3.08 2.27 Propylene, % by weight 16.54 15.14 14.06 10.57 4.59 C4 olefins, % by weight 10.02 9.04 8.76 6.25 3.42

[0175] As shown in Table 6, the composite catalyst provided in this disclosure has better heavy oil conversion capability and higher low-carbon olefin yield.

[0176] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0177] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0178] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A composite catalyst, characterized in that, The composite catalyst contains a phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve, a second molecular sieve, and a support. Based on the dry weight of the composite catalyst, the content of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 5-35% by weight, the content of the second molecular sieve is 10-50% by weight, and the content of the support is 30-80% by weight. The phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve has a hollow structure, an average grain size of 0.2-3.0 μm, and a bulk silicon-aluminum molar ratio to surface silicon-aluminum molar ratio of 1.0-1.5; the phosphorus-aluminum molar ratio of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 0.1-1.5; and the total specific surface area of ​​the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve is 340-400 m². 2 / g, mesoporous specific surface area is 40-150m² 2 / g, wherein the mesoporous specific surface area accounts for 15-40% of the total specific surface area; the strong Brønsted acid content of the phosphorus-containing hollow ZSM-5 multi-level porous molecular sieve accounts for 65-80% of the total Brønsted acid content, and the strong Lewis acid content accounts for 50-75% of the total Lewis acid content. The second molecular sieve is a molecular sieve with a pore size of 0.56-0.75 nm, or the second molecular sieve is a Y-type molecular sieve containing rare earth elements.

2. The composite catalyst according to claim 1, wherein, The phosphorus-aluminum molar ratio of the phosphorus-containing hollow ZSM-5 multi-level porous molecular sieve is 0.2-1.

3.

3. The composite catalyst according to claim 1, wherein, The average grain size of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve crystals is 0.4-2.5 μm, the ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio is 1.1-1.4, and the relative crystallinity is 75-90%.

4. The composite catalyst according to claim 1, wherein, The total specific surface area of ​​the phosphorus-containing hollow ZSM-5 multi-level porous molecular sieve is 350-400 m². 2 / g, mesoporous specific surface area is 45-140m² 2 / g, wherein the mesoporous specific surface area accounts for 20-35% of the total specific surface area.

5. The composite catalyst according to claim 1, wherein, The molecular sieve with an aperture size of 0.56-0.75 nm is one or more of the molecular sieves having AET, AFR, AFS, AFI, BEA, BOG, CFI, CON, GME, IFR, ISV, LTL, MEI, MOR, OFF and SAO structures; The rare earth content of the Y-type molecular sieve, calculated as rare earth element oxides, is 2-25% by weight, and the rare earth element is lanthanum and / or cerium; the phosphorus content of the Y-type molecular sieve, calculated as P2O5, is 0-10% by weight; the Y-type molecular sieve is selected from one or more of REY molecular sieve, DASY molecular sieve, USY molecular sieve, phosphorus-containing DASY molecular sieve, phosphorus-containing USY molecular sieve, PSRY molecular sieve, HRY molecular sieve, HSY molecular sieve, and SCY molecular sieve.

6. The composite catalyst according to claim 5, wherein, The molecular sieve with an aperture size of 0.56-0.75 nm is at least one of Beta, SAPO-5, SAPO-40, SSZ-13, CIT-1, ITQ-7, ZSM-18, mordenite, and sodium chalcogenide.

7. The composite catalyst according to claim 1, wherein, The carrier is selected from one or more of the following: natural clay, alumina carrier, silica carrier, aluminum phosphate carrier, and silica-alumina oxide carrier.

8. The composite catalyst according to claim 7, wherein, The silica carrier is one or more of neutral silica sol, acidic silica sol, or alkaline silica sol; the alumina carrier is one or more of alumina sol, acidified boehmite, hydrated alumina, and activated alumina; the aluminum phosphate carrier is aluminum phosphate gel; and the aluminosilicate carrier is selected from one or more of solid aluminosilicate materials, aluminosilicate sol, and aluminosilicate gel.

9. The composite catalyst according to claim 1, wherein, The support includes a silica support; based on the dry weight of the composite catalyst, the silica support has a SiO2 content of 1-20% by weight.

10. A method for preparing the composite catalyst according to any one of claims 1-9, the method comprising: The slurry containing a carrier, a phosphorus-containing hollow ZSM-5 multi-level porous molecular sieve, a second molecular sieve, and water is subjected to a first drying and optionally a first calcination.

11. The method according to claim 10, wherein, The preparation steps of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve include: (1) Mix and stir the first organosilicon source and the first solvent at 30-50°C for 0.5-5 hours, then heat to 70-100°C and mix and stir for 2-10 hours. Mix the resulting mixed liquid with the first template agent at 20-30°C for 0.5-3.0 hours to obtain the first mixed product. (2) Mix the first alkali metal hydroxide (calculated as alkali metal oxide), the second solvent, and the first aluminum source (calculated as Al2O3) in a molar ratio of (1.5-5):(60-350):1 at 20-80°C for 0.5-2.0 hours to obtain the second mixed product; (3) The first mixed product and the second mixed product are mixed and then dynamically crystallized. The resulting solid is taken out and subjected to a second calcination to obtain the first solid product. (4) The first solid product is mixed with the first alkaline solution, and the temperature is raised to the reaction temperature at a rate of 1-5℃ / min. The reaction is carried out at the reaction temperature for 10-90 min to obtain the second solid product. The reaction temperature is 60-90℃, and the alkaline content in the first alkaline solution is 0.45-2 mol / L. (5) The second solid product is subjected to a first ammonium exchange and optionally a sixth calcination to obtain a third solid product; (6) The third solid product is mixed with a second solution containing a phosphorus source, and the resulting first slurry is subjected to a second drying and a third calcination; or, The preparation steps of the phosphorus-containing hollow ZSM-5 hierarchical porous molecular sieve include: S1. The second template agent, the second inorganic silicon source, and the third solvent are mixed at 30-50°C for 0.5-3.0 hours. The resulting third mixed product is subjected to a first hydrothermal treatment and a second hydrothermal treatment in sequence to obtain a fourth mixed product. The conditions for the first hydrothermal treatment are: temperature 80-150°C and time 1-6 hours; the conditions for the second hydrothermal treatment are: temperature 160-180°C and time 4-60 hours. S2. Mix the second alkali metal hydroxide (calculated as alkali metal oxide), the fourth solvent, and the second aluminum source (calculated as Al2O3) in a molar ratio of (1.5-5):(60-350):1 at 20-80°C for 0.5-2.0 hours to obtain the fifth mixed product. S3. Mix the fourth mixed product and the fifth mixed product, subject the resulting mixture to a third hydrothermal treatment, remove the resulting solid and subject it to a fourth calcination to obtain a fourth solid product; S4. The fourth solid product is mixed with the third alkaline solution, and the temperature is increased to the reaction temperature at a rate of 1-5℃ / min. The mixture is then reacted at the reaction temperature for 10-90 min to obtain the fifth solid product. The reaction temperature is 60-90℃, and the alkaline content in the third alkaline solution is 0.45-2 mol / L. S5. The fifth solid product is subjected to a second ammonium exchange, and optionally a seventh calcination is performed to obtain the sixth solid product. S6. The sixth solid product is mixed with the fourth solution containing a phosphorus source, and the resulting second slurry is subjected to a third drying and a fifth calcination.

12. The method according to claim 11, wherein, The first organosilicon source is selected from methyl orthosilicate and / or ethyl orthosilicate; The second inorganic silicon source is selected from one or more of silica sol, water glass, and solid silica gel; The first template agent and the second template agent are each independently selected from one or more of tetrapropylammonium bromide, tetrapropylammonium hydroxide, n-butylamine and hexamethylenediamine; The first aluminum source and the second aluminum source are each independently selected from one or more of sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum isopropoxide and aluminum sol; The first alkali metal hydroxide and the second alkali metal hydroxide are each independently selected from one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide; The first alkaline solution and the third alkaline solution are each independently selected from one or more of sodium hydroxide solution, potassium hydroxide solution, lithium hydroxide solution and barium hydroxide solution; The phosphorus source is selected from one or more of phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and ammonium phosphate.

13. The method according to claim 11, wherein, The molar ratio of the total amount of the first template agent, the first solvent, and the second solvent, the first alkali metal hydroxide, to the amount of the first organosilicon source is (0.06-0.55):(10-100):(0.02-1.5):1; the molar ratio of the first organosilicon source to the first aluminum source is (20-500):1; wherein, the first organosilicon source is calculated as SiO2, the first alkali metal hydroxide is calculated as alkali metal oxide, and the first aluminum source is calculated as Al2O3; The total amount of the second template agent, the third solvent, and the fourth solvent, the molar ratio of the second alkali metal hydroxide to the second inorganic silicon source is (0.06-0.55):(10-100):(0.02-1.5):1, and the molar ratio of the second inorganic silicon source to the second aluminum source is (20-500):1; wherein the second inorganic silicon source is calculated as SiO2, the second alkali metal hydroxide is calculated as alkali metal oxide, and the second aluminum source is calculated as Al2O3.

14. The method according to claim 13, wherein, In step (2), the molar ratio of the first alkali metal hydroxide (calculated as alkali metal oxide), the second solvent, and the first aluminum source (calculated as Al2O3) is (2-4.5):(80-350):1; In step S2, the molar ratio of the second alkali metal hydroxide (calculated as alkali metal oxide), the fourth solvent, and the second aluminum source (calculated as Al2O3) is (2-4.5):(80-350):

1.

15. The method according to claim 13, wherein, In step (4), the molar ratio of the first solid product to the first alkaline solution is 1:(2-10), the first solid product is calculated as SiO2, and the first alkaline solution is calculated as alkali metal oxide; the ratio of the bulk silicon-aluminum molar ratio to the surface silicon-aluminum molar ratio of the first solid product is 1.2-5.

0. In step S4, the molar ratio of the fourth solid product to the third alkaline solution is 1:(2-10), the fourth solid product is calculated as SiO2, the third alkaline solution is calculated as alkali metal oxide, and the ratio of the bulk silicon-aluminum molar ratio and the surface silicon-aluminum molar ratio of the fourth solid product is 1.2-5.

0.

16. The method according to claim 13, wherein, In step (6), the weight ratio of the second solution containing the phosphorus source to the third solid product is 1:(0.5-2.0); In step S6, the weight ratio of the fourth solution containing the phosphorus source to the sixth solid product is 1:(0.5-2.0).

17. The method according to claim 11, wherein, The conditions for dynamic crystallization include: a temperature of 160-180℃ and a time of 12-60 hours; The conditions for the third hydrothermal treatment include: a temperature of 160-180℃ and a time of 12-60 hours; The conditions for the second, third, fourth, and fifth calcinations each independently include: a temperature of 400-600℃ and a time of 2-6 hours; The conditions for the second drying and the third drying each independently include: a temperature of 90-120°C and a time of 2-24 hours.

18. The method according to claim 10, wherein, The method further includes: mixing catalyst particles obtained from the first drying and optionally the first calcination, ammonium salt and a fifth solvent in a weight ratio of 1:(0.1-1):(5-15) for a third ammonium exchange, and optionally washing; The conditions for the third ammonium exchange include: a temperature of 50-100℃ and a time of 0.5-2 hours; The ammonium salt is selected from one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate.

19. The application of the composite catalyst according to any one of claims 1-9 in increasing the production of low-carbon olefins in hydrogenated LCO catalytic cracking or heavy oil catalytic cracking.

Images