Single-crystal hollow ZSM-5 molecular sieve, and catalyst containing molecular sieve and preparation method therefor and use thereof

Abstract

A single-crystal hollow ZSM-5 molecular sieve, and a catalyst containing the molecular sieve and a preparation method therefor and a use thereof. Particles of the single-crystal hollow ZSM-5 molecular sieve have a single-crystal structure with an average crystal grain size of 0.8-3.5 μm, and have an internally and externally nested double-layer cavity structure, wherein an inner cavity is at least partially closed by a first molecular sieve wall layer, an outer cavity is completely closed by a second molecular sieve wall layer, and an epitaxially grown nanorod shell layer is provided on the second molecular sieve wall layer. The single-crystal hollow ZSM-5 molecular sieve can be used for macromolecular catalytic cracking reaction, allowing for a higher low-carbon olefin yield, a higher BTX yield, and a higher ethylene / propylene ratio.

Description

A single crystal hollow ZSM-5 molecular sieve, a catalyst containing the molecular sieve, and its preparation method and use Technical Field

[0001] The present invention belongs to the technical field of catalytic materials, and relates to a single crystal hollow ZSM-5 molecular sieve, a preparation method and use thereof, and also relates to a catalytic cracking catalyst comprising the single crystal hollow ZSM-5 molecular sieve, a preparation method and use thereof. Background Art

[0002] Petroleum is an important source of automotive fuel and organic raw materials. Petroleum is a mixture of hydrocarbons that is often fractionated during processing, leaving a large portion of the product as heavy oil. However, heavy oil is difficult to use directly and requires further processing and conversion. Refineries often catalytically crack heavy oil into different products and adjust the ratio of these products based on market demand. For example, some refineries primarily produce automotive fuels such as gasoline and diesel, others focus on gasoline and light olefins, and still others focus on producing chemical raw materials, aiming to minimize gasoline and diesel production. A key factor in the catalytic cracking of heavy oil into different products is the catalytic cracking catalyst.

[0003] Catalytic cracking catalysts are the technical core of the petrochemical industry and the source of technological progress in the petrochemical industry. Catalytic cracking to produce light olefins is a typical high-temperature acid-catalyzed reaction, and its core is the development and design of catalytic materials. Catalytic cracking often adjusts the target product according to market demand. ZSM-5 molecular sieve has a unique pore structure, adjustable acidity and high thermal / hydrothermal stability, making it the first choice for hydrocarbon catalytic cracking catalysts. However, although its regular and orderly microporous structure enhances the selectivity of specific products, it also limits the diffusion of large molecular hydrocarbon reactants and products, and also promotes the formation of carbon deposits, further covering active sites and causing catalyst deactivation. The existing technology has proposed hollow ZSM-5 molecular sieves, but these hollow ZSM-5 molecular sieves have a single morphology and are mostly synthesized using a large amount of organic templates.

[0004] Light olefins (ethylene, propylene, etc.) are important petrochemical raw materials. With the rapid development of the global economy, the petrochemical industry is experiencing rapid growth, and demand for light olefins is increasing dramatically. Ethylene, in particular, is a crucial raw material supporting national economic and social development and is known as the "mother of petrochemicals." The scale, output, and technological level of its industrial production have become important indicators of a country's chemical industry status. Catalytic cracking of hydrocarbons is an important method for converting larger hydrocarbons into smaller hydrocarbons, such as ethylene and propylene. During the cracking process, hydrocarbons undergo a large number of parallel and sequential reactions. In addition to cracking to produce smaller hydrocarbons, they may also aromatize to form aromatics. The resulting side-chain aromatics may further crack or dealkylate to form BTX light aromatics, or they may undergo hydrogen transfer to form heavier aromatics. In refineries, production of more ethylene and more propylene may be desired, depending on the needs of the refinery, requiring the ability to flexibly adjust the product ratio.

[0005] Ethylene production primarily involves naphtha cracking, coal / methanol to olefins, heavy oil catalytic cracking / catalytic cracking, and light hydrocarbon cracking. Catalytic cracking, using heavy oil, naphtha, and light olefins as primary feedstocks, can produce ethylene at relatively low reaction temperatures under the action of a catalyst. This offers advantages such as flexible product distribution, lower energy consumption, and a relatively eco-friendly profile.

[0006] Catalytic cracking of heavy oils involves converting heavy oils under more demanding conditions, using catalysts that increase the yield of light olefins and appropriately adjusting reaction conditions, such as increasing the reaction temperature, based on catalytic cracking. Catalytic cracking catalysts are a key factor influencing the catalytic cracking of heavy oils. Co-production of BTX during the catalytic cracking reaction provides flexibility for subsequent product adjustments. Aromatic hydrocarbons generated by hydrocarbon cracking are a byproduct of light olefin production. However, prior art does not disclose how to simultaneously achieve higher BTX yields while achieving higher ethylene yields.

[0007] CN103157507A discloses a catalytic cracking catalyst comprising 2-50% by weight of an ultrastable rare earth Y-type molecular sieve, 0.5-30% by weight of one or more other molecular sieves, 0.5-70% by weight of clay, 1.0-65% by weight of a high-temperature-resistant inorganic oxide, and 0.01-12.5% ​​by weight of a rare earth oxide. The catalyst has strong heavy oil conversion capabilities and a high light oil yield. This catalyst is primarily used to increase gasoline yield, but has limited contribution to increasing light olefin yields.

[0008] CN112138712A discloses a catalytic cracking catalyst, a preparation method thereof, and a method for catalytic cracking of hydrocarbon oil. The catalyst contains 1 to 30 weight percent, based on dry weight, of a Y-type molecular sieve; 5 to 55 weight percent, based on dry weight, of a mesoporous, phosphorus- and metal-containing MFI-structured molecular sieve; 1 to 60 weight percent, based on dry weight, of an inorganic binder; and optionally, 0 to 60 weight percent, based on dry weight, of a second clay. The inorganic binder includes a phosphorus-aluminum inorganic binder and / or other inorganic binders. The catalyst has better ethylene selectivity in the catalytic cracking reaction of petroleum hydrocarbons and can simultaneously produce more propylene and BTX.

[0009] In recent years, the raw materials have become heavier and inferior in quality. The existing technology does not involve catalysts that can further improve the conversion of heavy oil and increase the yield of light olefins under different working conditions.

[0010] Summary of the Invention

[0011] The present invention aims to provide a novel molecular sieve that can be used in the fields of petrochemicals and / or fine chemicals, as well as a preparation method and use thereof. This molecular sieve can be used to prepare catalysts used in the fields of petrochemicals and / or fine chemicals, in particular to prepare catalytic cracking catalysts for increasing the production of light olefins such as ethylene, propylene and BTX in catalytic cracking reactions.

[0012] The inventors have discovered that by adjusting the pore structure and acid center distribution of the molecular sieve, the formation of aromatics can be partially inhibited or promoted. This adjustable property makes it possible to adjust the distribution of catalytic cracking products. Not only can light olefins be produced through catalytic cracking, but a higher BTX component can also be obtained in the cracking products, providing a reasonable product distribution for subsequent utilization of the products. However, to date, those skilled in the art do not know how to perform such adjustments.

[0013] To this end, according to the first aspect of the present invention, the present invention provides a single-crystal hollow ZSM-5 molecular sieve, wherein the particles of the single-crystal hollow ZSM-5 molecular sieve have a single-crystal structure, an average grain size of 0.8-3.5 μm, and a double-layer cavity structure with inner and outer layers nested, wherein the inner cavity is at least partially enclosed by a first molecular sieve wall layer, and the outer cavity is completely enclosed by a second molecular sieve wall layer, and an epitaxially grown nanorod shell layer is provided on the second molecular sieve wall layer; preferably, the ZSM-5 molecular sieve crystals grow along the ac axis direction.

[0014] According to a second aspect of the present invention, the present invention provides a method for preparing a single-crystal hollow ZSM-5 molecular sieve, wherein the particles of the single-crystal hollow ZSM-5 molecular sieve have a single crystal structure, an average grain size of 0.8-3.5 μm, and a double-layer cavity structure with an inner and outer layer and an epitaxially grown nanorod shell, wherein the inner cavity is at least partially enclosed by a first molecular sieve wall layer, and the outer cavity is completely enclosed by a second molecular sieve wall layer. The method comprises the steps of (A) preparing a molecular sieve seed solution and (B) preparing a single-crystal hollow ZSM-5 molecular sieve:

[0015] Wherein step (A) comprises the following sub-steps:

[0016] (A1) mixing a first silicon source, a template, and water to obtain a first mixed solution;

[0017] (A2) subjecting the first mixed solution obtained in sub-step (A1) to hydrothermal dynamic crystallization to obtain a seed solution;

[0018] Step (B) comprises the following sub-steps:

[0019] (B1) adding the alkaline source solution, the second silicon source dispersion, and the aluminum source dispersion sequentially into water under stirring to obtain a second mixed solution;

[0020] (B2) adding a certain amount of the seed solution to the second mixed solution under stirring to obtain a third mixed solution;

[0021] (B3) subjecting the third mixed solution to hydrothermal dynamic crystallization; filtering the obtained product, optionally washing, drying, and calcining to obtain a parent molecular sieve;

[0022] (B4) mixing the obtained parent molecular sieve with an alkali solution to obtain a solid product; and optionally

[0023] (B5) treating the obtained solid product to obtain an H-type single crystal hollow ZSM-5 molecular sieve, and optionally

[0024] (B6) Introducing phosphorus into the H-type single crystal hollow ZSM-5 molecular sieve obtained in sub-step (B5).

[0025] According to the third aspect of the present invention, the present invention also relates to the use of a single crystal hollow ZSM-5 molecular sieve provided according to the above first aspect or a single crystal hollow ZSM-5 molecular sieve obtained by the method according to the above second aspect, for example, in the fields of petrochemicals and / or fine chemicals.

[0026] According to the fourth aspect of the present invention, the present invention also provides a catalyst, especially a catalytic cracking catalyst, containing a single crystal hollow ZSM-5 molecular sieve provided by the above first aspect or a single crystal hollow ZSM-5 molecular sieve obtained by the method according to the above second aspect.

[0027] According to a fifth aspect of the present invention, the present invention also provides a method for preparing the catalyst according to the fourth aspect.

[0028] According to the sixth aspect of the present invention, the present invention also relates to the use of the catalyst according to the fourth aspect for catalytic cracking of heavy oil to increase the production of light olefins (ethylene, propylene, etc.) and BTX. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to illustrate the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention.

[0030] FIG1 shows a transmission electron microscope image of the single-crystalline hollow ZSM-5 molecular sieve prepared in Example 1.

[0031] FIG2 shows the Fourier transform diffraction spectrum of the single crystal hollow ZSM-5 molecular sieve prepared in Example 1. DETAILED DESCRIPTION

[0032] The following specific embodiments describe the preferred technical solutions of the present invention in detail. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the scope of the present invention.

[0033] Any specific numerical value disclosed in the present specification (including the endpoints of a numerical range) is not limited to the exact value of the numerical value, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Moreover, for a disclosed numerical range, the values ​​between the endpoints of the range, between the endpoints and the specific points in the range, and between the specific points can be arbitrarily combined to form one or more new numerical ranges, and these new numerical ranges should also be considered to be specifically disclosed herein.

[0034] Unless otherwise specified, the terms used in the specification of the present invention have the same meanings as commonly understood by those skilled in the art. If a term is defined herein and its definition is different from the commonly understood meaning in the art, the definition in this article shall prevail.

[0035] In the description of the present invention, except for the contents explicitly described, any matters or issues not mentioned are directly applicable to those known in the art without any changes. Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas formed thereby are considered part of the original disclosure or original description of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0036] All patent and non-patent literature, including but not limited to textbooks and journal articles, mentioned in the specification of the present invention are incorporated herein by reference in their entirety.

[0037] In the present description, the term "comprising" is synonymous with "including" and "containing", and is inclusive or open, without excluding other elements not specified. It should be understood that the term "comprising" includes the exclusive and closed term "consisting of . . . "Based on" is synonymous with "comprising at least 80% by weight". In the absence of explicit instructions, the percentages given are weight %. In addition, in this description, the term "substantially" or "essentially" corresponds to an approximation of ±5%, preferably ±1%, very preferably ±0.5%, for example ±0.1%. For example, an effluent that substantially comprises compound A or is substantially composed of compound A corresponds to an effluent that comprises at least 95% by weight of compound A.

[0038] The measurement of various parameters disclosed in the specification of the present invention, unless otherwise specified, is carried out by the most common methods in the art.

[0039] As described above, according to the first aspect of the present invention, the present invention provides a single-crystal hollow ZSM-5 molecular sieve, the particles of which have a double-layer cavity structure with inner and outer layers nested and an epitaxially grown nanorod shell, wherein the inner cavity is at least partially enclosed by the first molecular sieve wall layer, and the outer cavity is completely enclosed by the second molecular sieve wall layer; preferably, the ZSM-5 molecular sieve crystals grow along the ac axis direction.

[0040] For the single crystal hollow ZSM-5 molecular sieve according to the present invention, as shown in FIG1 , the expression “double layer” is intended to indicate that the single crystal hollow ZSM-5 molecular sieve comprises two molecular sieve wall layers (a first molecular sieve wall layer and a second molecular sieve wall layer) alternately surrounding each other and two inner and outer cavities, that is, the first molecular sieve wall layer at least partially surrounds the inner cavity and exists in the form of an at least partially complete molecular sieve wall layer between the inner cavity and the outer cavity of the molecular sieve crystal, and the second molecular sieve wall layer surrounds the outer cavity and exists in the form of a complete molecular sieve between the outer cavity of the molecular sieve crystal and the outside of the crystal. The ZSM-5 molecular sieve particles are in the form of a single-crystal ZSM-5 molecular sieve wall layer, and further include an epitaxially grown nanorod shell layer on the outer wall of the second molecular sieve wall layer; the expression "single crystal" is intended to indicate that the ZSM-5 molecular sieve particles have a single-crystal structure; the expression "hollow" and the expression "cavity" in this specification can be used equivalently, and are intended to indicate that there is a space in the ZSM-5 molecular sieve grains that does not contain the ZSM-5 molecular sieve, and the space is at least partially enclosed by a ZSM-5 molecular sieve wall layer having a certain thickness, that is, the cavity of the molecular sieve can be formed by partially enclosing the molecular sieve wall or by completely enclosing the molecular sieve wall.

[0041] The single crystal hollow ZSM-5 molecular sieve according to the present invention is a single crystal structure with an average grain size of 0.8-3.5 μm, preferably 1.0-3.2 μm, more preferably 1.5-3.0 μm; a nanorod structure is provided on the surface of the single crystal, the axial direction of the nanorod structure extending along the ac axis direction (along the 010 plane), and the growth orientation of the individual grains of the single crystal hollow ZSM-5 molecular sieve is consistent, that is, growing along the ac axis direction. And the morphological characteristics of this nanorod shell have the characteristics of "short straight channels and long sinusoidal channels", which increases the number of straight channel orifices (further significantly improves the accessibility of the active center), increases the number of channel cross cavities, that is, increases the ratio of acidic sites at the cross channels, and realizes the dual modulation of the molecular sieve channel structure and acid properties. The crystal structure and growth orientation of the single crystal hollow ZSM-5 molecular sieve can be observed by a high-power spherical aberration electron microscope.

[0042] As described above, the single crystal hollow ZSM-5 molecular sieve provided by the present invention has a double-layer closed cavity and an epitaxially grown nanorod shell; more specifically, the single crystal hollow ZSM-5 molecular sieve has a grain length of 0.8-3.5 μm, preferably 1.0-3.0 μm, for example, 1.5 μm, 2.0 μm or 2.5 μm, and a grain width of 0.5-2.0 μm, preferably 0.8-1.7 μm, for example, 1.0 μm, 1.2 μm or 1.5 μm; the length of the inner cavity is 0.5-2.0 μm, preferably 0.8-1.5 μm, for example, 1.0 μm, 1.2 μm or 1.5 μm. 1.4 μm; the width of the inner cavity is 0.3-1.0 μm, preferably 0.4-0.8 μm, for example 0.5 μm, 0.6 μm or 0.7 μm; the thickness of the first molecular sieve wall layer (i.e. the distance between the outer wall surface of the inner cavity and the inner wall surface of the outer cavity) is generally less than 500 nm, for example 100-400 nm, preferably 200-350 nm, for example 250 nm, 280 nm or 300 nm; the thickness of the second molecular sieve wall layer (i.e. the distance between the outer wall surface of the outer cavity and the outer wall surface of the molecular sieve crystal) is generally less than 500 nm, for example 40-400 nm, preferably 100-300 nm, and the length of the epitaxially grown nanorods is 0.5-1.0 μm, preferably 0.6-0.9 μm, for example 0.7 μm or 0.8 μm.

[0043] The "grain size" of a molecular sieve refers to the size of the largest dimension of the grain, which can be obtained by measuring the size of the widest part of the grain projection in the SEM or TEM image of the molecular sieve sample. The average grain size is obtained by selecting any 10 molecular sieve grains in the SEM or TEM image and calculating the arithmetic mean of their grain sizes. The grain length refers to the length along the ac axis, and the width refers to the dimension perpendicular to the length direction. For the purposes of the present invention, the "grain size" of a molecular sieve is equivalent to the "grain length". The length of the inner cavity refers to the dimension of the longest projection of the inner cavity, the width of the inner cavity refers to the dimension perpendicular to the length direction of the inner cavity, the thickness of the first molecular sieve wall layer (i.e., the distance between the outer wall surface of the inner cavity and the inner wall surface of the outer cavity) is the distance obtained by randomly measuring between the outer wall surface of the inner cavity and the inner wall surface of the outer cavity; the length of the outer cavity refers to the dimension of the longest projection of the outer cavity structure, the width of the outer cavity refers to the dimension perpendicular to the length direction of the outer cavity, the thickness of the second molecular sieve wall layer (i.e., the distance between the outer wall surface of the outer cavity and the outer wall surface of the molecular sieve crystal, excluding the thickness of the nanorod-shaped shell layer) is the distance obtained by randomly measuring between the inner wall of the outer cavity and the outer wall of the molecular sieve crystal. As an illustration, the grain length, grain width, cavity length, cavity width and molecular sieve wall thickness of the molecular sieve sample are obtained by randomly selecting 10 molecular sieve grains from the SEM or TEM image of the molecular sieve sample, measuring their grain length, grain width, cavity length, cavity width and molecular sieve wall thickness, and calculating their arithmetic average.

[0044] The molecular sieve obtained by modifying the single crystal hollow ZSM-5 molecular sieve under the condition of a phosphorus / aluminum molar ratio of 1 has a crystallization retention rate greater than or equal to 90%, for example, 90-98% or 90.2-95%, and / or an acid retention rate greater than or equal to 30%, for example, 30-40% or 30.5-35%, after hydrothermal treatment at 800°C for 17 hours, indicating that the molecular sieve has good hydrothermal stability after phosphorus modification. The crystallinity retention refers to the ratio of the relative crystallinity of the product obtained after the molecular sieve is modified at a phosphorus / aluminum molar ratio of 1 and then hydrothermally treated at 800°C for 17 hours (referred to as the relative crystallinity after hydrothermal treatment) to the relative crystallinity of the product obtained after the molecular sieve is modified at a phosphorus / aluminum molar ratio of 1 (referred to as the relative crystallinity before hydrothermal treatment); the acidity retention refers to the ratio of the acidity of the product obtained after the molecular sieve is modified at a phosphorus / aluminum molar ratio of 1 and then hydrothermally treated at 800°C for 17 hours (referred to as the acidity after hydrothermal treatment) to the acidity of the product obtained after the molecular sieve is modified at a phosphorus / aluminum molar ratio of 1 (referred to as the acidity before hydrothermal treatment). The hydrothermal treatment is carried out in an atmosphere of 100% by volume water vapor.

[0045] The modification of the single crystal hollow ZSM-5 molecular sieve under the condition of a phosphorus / aluminum molar ratio of about 1 can be implemented by an equal volume impregnation method, which is as follows: the molecular sieve sample is evenly spread on a watch glass or a crucible, and the phosphorus-containing solution is slowly poured onto the molecular sieve sample so that the molecular sieve sample finally presents a "slurry state", and after stirring evenly, it is dried in an oven; then it is evenly ground and calcined at 550°C for 4 hours. Usually, the mass ratio of the phosphorus-containing solution to the molecular sieve is 1-3. The phosphorus-containing solution is, for example, a phosphoric acid solution or an ammonium dihydrogen phosphate solution or a diammonium hydrogen phosphate solution. In the present invention, the phosphorus / aluminum molar ratio of the single crystal hollow ZSM-5 molecular sieve can be obtained by XRF fluorescence detection.

[0046] The relative crystallinity of the molecular sieve according to the present invention is calculated based on the XRD standard ZSM-5 molecular sieve standard sample of Sinopec Research Institute of Petroleum Processing Co., Ltd., and the crystallinity of the standard sample is regarded as 100%.

[0047] According to a preferred embodiment of the first aspect above, the mesoporous specific surface area of ​​the single crystal hollow ZSM-5 molecular sieve accounts for 15-25% of the total specific surface area, preferably 18-23%, and more preferably 20-22%.

[0048] According to a preferred embodiment of the first aspect above, the mesopore volume of the single crystal hollow ZSM-5 molecular sieve accounts for 40-60% of the total pore volume, preferably 45-55%, and more preferably 48-52%.

[0049] The total specific surface area, mesopore specific surface area, micropore specific surface area, and pore volume of the single crystal hollow ZSM-5 molecular sieve according to the present invention are measured using a low-temperature nitrogen adsorption method, the BET specific surface area is calculated using the BET formula, the micropore area is calculated using a t-plot, and the pore size distribution is calculated using BJH. Therefore, the single crystal hollow molecular sieve of the present invention is mainly microporous and rich in mesopores and macropores, which can further provide multi-directional diffusion paths, expand the confined space, improve the accessibility of the active center of the molecular sieve, and have the ability to catalyze the cracking of macromolecular hydrocarbon compounds.

[0050] The single crystal hollow ZSM-5 molecular sieve according to the present invention can be an H-type single crystal hollow ZSM-5 molecular sieve or a phosphorus-containing single crystal hollow ZSM-5 molecular sieve. The phosphorus content of the phosphorus-containing single crystal hollow ZSM-5 molecular sieve can be greater than 0 to 15% by weight, for example, 0.5-10% by weight, calculated as P2O5. In the phosphorus-containing double-layer single crystal mesoporous ZSM-5 molecular sieve, the phosphorus / aluminum molar ratio (P / Al molar ratio) is preferably 0.5-1.5, for example, 0.8-1.2 or 1.

[0051] According to a second aspect of the present invention, the present invention provides a method for preparing a single-crystalline hollow ZSM-5 molecular sieve, in particular a single-crystalline hollow ZSM-5 molecular sieve according to the first aspect of the present invention, wherein the particles of the single-crystalline hollow ZSM-5 molecular sieve have a double-layer cavity structure with an inner and outer layer nested and an epitaxially grown nanorod shell, wherein the inner cavity is at least partially enclosed by a first molecular sieve wall layer, and the outer cavity is completely enclosed by a second molecular sieve wall layer, the ZSM-5 molecular sieve grows along the ac axis direction, and the entire particle has a single crystal structure, the method comprising step (A) for preparing a seed solution and step (B) for preparing a single-crystalline hollow ZSM-5 molecular sieve:

[0052] Wherein, step (A) comprises the following sub-steps:

[0053] (A1) mixing a first silicon source, a template, and water to obtain a first mixed solution;

[0054] (A2) subjecting the first mixed solution obtained in sub-step (A1) to hydrothermal dynamic crystallization to obtain a seed solution;

[0055] Step (B) comprises the following sub-steps:

[0056] (B1) adding the alkaline source solution, the second silicon source dispersion, and the aluminum source dispersion sequentially into water under stirring to obtain a second mixed solution;

[0057] (B2) adding a certain amount of the seed solution to the second mixed solution under stirring to obtain a third mixed solution;

[0058] (B3) subjecting the third mixed solution to hydrothermal dynamic crystallization; filtering the obtained product, optionally washing, drying, and calcining to obtain a parent molecular sieve;

[0059] (B4) mixing the obtained parent molecular sieve with an alkali solution to obtain a solid product; and optionally

[0060] (B5) treating the obtained solid product to obtain an H-type single crystal hollow ZSM-5 molecular sieve, and optionally

[0061] (B6) Introducing phosphorus into the H-type single crystal hollow ZSM-5 molecular sieve obtained in sub-step (B5).

[0062] According to a specific embodiment of the above-mentioned method for preparing molecular sieves, the present invention provides a method for preparing a single crystal hollow ZSM-5 molecular sieve, in particular a method for preparing a single crystal hollow ZSM-5 molecular sieve according to the first aspect of the present invention, the method comprising step (A) for preparing a seed solution and step (B) for preparing a single crystal hollow ZSM-5 molecular sieve:

[0063] Wherein, step (A) comprises the following sub-steps:

[0064] Step (A) comprises the following sub-steps:

[0065] (A1) mixing a first silicon source, a template, and water under stirring, preferably at 30-60° C. for 2-6 hours to obtain a mixed solution, referred to as a first mixed solution;

[0066] (A2) subjecting the first mixed solution obtained in sub-step (A1) to hydrothermal dynamic crystallization at a temperature of 140-180° C. for, for example, 8-24 hours, preferably 10-18 hours, by transferring the mixed solution to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and subjecting the mixture to hydrothermal crystallization under stirring to obtain a solution containing a crystallized product, referred to as a seed solution;

[0067] Step (B) comprises the following sub-steps:

[0068] (B1-1) dissolving an alkali source in water and stirring uniformly to obtain an alkali source solution;

[0069] (B1-2) mixing an aluminum source with water and stirring uniformly to obtain an aluminum source dispersion;

[0070] (B1-3) mixing the second silicon source with the alkali source solution obtained in sub-step (B1-1) under stirring, preferably at room temperature for more than 5 minutes, for example, 10-30 minutes;

[0071] (B1-4) optionally mixing the product obtained in sub-step (B1-3) with a certain amount of dilution water, and then mixing with the aluminum source dispersion obtained in sub-step (B1-2) under stirring, preferably stirring at room temperature for a sufficient time, for example, more than 1 minute, preferably 30-60 minutes, to obtain a mixed solution, referred to as a second mixed solution;

[0072] (B2) adding a certain amount of the seed solution obtained in sub-step (A2) to the second mixed solution obtained in sub-step (B1-4) under stirring, preferably stirring at room temperature for more than 10 minutes, for example, stirring for 1-6 hours, to obtain a mixed solution, referred to as a third mixed solution; preferably, the ratio of the mass of SiO2 in the seed solution to the mass of SiO2 in the product obtained in sub-step (B1-4) is 5-20:100, for example, 10:100 or 15:100;

[0073] (B3) subjecting the third mixed solution obtained in sub-step (B2) to hydrothermal dynamic crystallization at a temperature above 100° C. for, for example, more than 1 hour, for example, at a temperature of 140-180° C., preferably 150-170° C., for 6-48 hours, preferably 10-40 hours; filtering the obtained product, optionally washing, drying, and calcining to obtain a parent molecular sieve;

[0074] (B4) mixing the parent molecular sieve obtained in sub-step (B3) with an alkali-containing solution under stirring, for example, at a temperature of 60-90° C. for 20-60 minutes, preferably, the alkali content in the alkali-containing solution is 0.4-2.0 mol / L, to obtain a solid product; and optionally

[0075] (B5) treating the solid product obtained in sub-step (B4) to obtain an H-type single crystal hollow ZSM-5 molecular sieve; and optionally

[0076] (B6) Introducing phosphorus into the H-type single crystal hollow ZSM-5 molecular sieve obtained in sub-step (B5).

[0077] For the purposes of the present invention, room temperature refers to a temperature of 20-35°C.

[0078] According to a preferred embodiment of the above-mentioned method for preparing molecular sieves, the silicon source (first silicon source) used in sub-step (A1) is selected from one or more of methyl orthosilicate and ethyl orthosilicate, and the template is selected from one or more of tetrapropylammonium hydroxide and tetrapropylammonium bromide.

[0079] According to a preferred embodiment of the above method for preparing molecular sieves, the molar ratio R / SiO2 of the template R used in sub-step (A1) to SiO2 in the first silicon source is 0.05-0.50, for example 0.1-0.4, and the molar ratio H2O / SiO2 is 10-80, for example 25-65.

[0080] According to a preferred embodiment of the above-mentioned method for preparing molecular sieves, the grain size of the seed crystals obtained in sub-step (A2) is 200-800 nm, preferably 300-700 nm, for example 400 nm, 500 nm or 600 nm; the grain size of the seed crystals is obtained by measuring the size of the largest dimension of randomly selected grains and then calculating their average value.

[0081] According to a preferred embodiment of the above method for preparing molecular sieves, in sub-step (B1-1), the concentration of the alkali source solution can be 10-30% by weight, preferably 15-25% by weight. The alkali source is selected from one or more of potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

[0082] According to a preferred embodiment of the above-mentioned method for preparing molecular sieves, in sub-step (B1-2), the concentration of the aluminum source solution is 5-20 weight %, preferably 10-15 weight %; and the aluminum source is selected from one or more of aluminum sulfate, aluminum nitrate, aluminum isopropoxide, sodium aluminate and aluminum chloride.

[0083] According to a preferred embodiment of the above-mentioned method for preparing molecular sieves, in sub-step (B1-3), the second silicon source is a silica sol, preferably selected from ammonium silica sol, sodium silica sol or a mixture thereof. Preferably, the SiO2 content in the silica sol is 15-45% by weight, for example, it can be 15% by weight, 25% by weight, 30% by weight, 45% by weight, relative to the total weight of the silica sol, or any value within the content range formed by combining any two of the above-mentioned values ​​as endpoints.

[0084] According to a preferred embodiment of the above-mentioned method for preparing molecular sieves, the molar ratio of the second mixed solution obtained in sub-step (B1-4) is: n(SiO2) / n(Al2O3)=20-200, for example, 30-100, preferably 40-80, more preferably 45-65; n(M12O) / n(SiO2)=0.2-0.5, for example, 0.22-0.5, preferably 0.25-0.50, more preferably 0.22-0.35; n(H2O) / n(SiO2)=50-150, for example, 60-120, preferably 75-110, wherein M1 represents an alkali metal, selected from one or more of K, Rb or Cs, preferably K.

[0085] According to a preferred embodiment of the above-mentioned method for preparing molecular sieves, in sub-step (B2), the ratio of the weight content of SiO2 in the seed solution to the weight content of SiO2 in the silicon source (called the second silicon source) in sub-step (B1-3) is 5-20:100, for example 6-10:100.

[0086] According to a preferred embodiment of the above-mentioned method for preparing molecular sieves, in sub-step (B3), the mixed solution obtained in sub-step (B2) is subjected to hydrothermal dynamic crystallization at a temperature above 100°C for more than 0.5 hours, preferably at a temperature of 140-180°C for 6-48 hours. For example, the mixed solution obtained in sub-step (B2) can be transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner, and then subjected to hydrothermal dynamic crystallization. The dynamic crystallization refers to performing a crystallization reaction on the mixed solution while in motion, such as under stirring.

[0087] According to a preferred embodiment of the above-mentioned method for preparing molecular sieves, in sub-step (B3), the obtained product is filtered to separate the crystallized molecular sieve from the mother liquor, and then washed with water to remove the mother liquor attached to the molecular sieve, for example, using deionized water, and then dried and calcined. The drying is carried out at a temperature above 40°C, for example, at a temperature of 50-150°C, for more than 0.5 hours, preferably 1-48 hours; the calcination can be carried out at a calcination temperature of 450-600°C, for example, 500-600°C, for more than 0.5 hours, for example, the calcination time is 2-12 hours, for example, 3-6 hours.

[0088] In sub-step (B3), the parent molecular sieve is obtained, which exists mainly in the form of solid crystals, the central part of which is rich in silicon and the peripheral part of which is rich in aluminum.

[0089] According to a preferred embodiment of the method for preparing molecular sieves, in sub-step (B4), the parent molecular sieve is mixed with an alkaline solution for more than 5 minutes under stirring, for example, at a temperature of 60-90 ° C, and stirred for 20-60 minutes, and the molecular sieve crystals are treated to form a hollow structure. The solid obtained is then recovered and filtered, and optionally washed, for example, with deionized water to wash away the residual alkali solution in the treated parent molecular sieve, and then dried to obtain a molecular sieve solid. The alkaline solution is, for example, an alkaline solution containing one or more of sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. The content of alkali in the alkaline solution is 0.4-2.0 mol / L in terms of metal molar amount, for example, 0.4-1 mol / L.

[0090] According to a preferred embodiment of the above-mentioned method for preparing molecular sieves, in sub-step (B5), the solid product obtained in sub-step (B4) is treated to obtain an H-type single crystal hollow ZSM-5 molecular sieve. According to one embodiment, the treatment includes subjecting the solid product obtained in sub-step (B4) to ion exchange, such as ammonium exchange, filtering, optionally washing, and then drying and calcining. The operation methods of the ammonium exchange, drying and calcining are well known to those skilled in the art. For example, drying can be carried out at a temperature above 40°C for at least 0.5 hours, and calcination can be carried out at a temperature above 400°C, preferably 500-600°C, for more than 0.5 hours, preferably 1-5 hours. According to a preferred embodiment, the ammonium exchange is referred to as the first ammonium exchange, wherein the temperature of the first ammonium exchange can be 50-95°C, the exchange time can be 0.5-2 hours, wherein the mass ratio of ZSM-5 molecular sieve, ammonium salt and water can be 1: (0.1-1): (5-15); the ammonium salt can be selected from one or more of ammonium chloride, ammonium sulfate and ammonium nitrate. The first ammonium exchange can be carried out once or multiple times.

[0091] According to a preferred embodiment of the above-mentioned method for preparing molecular sieves, in sub-step (B6), phosphorus is introduced into the H-type single crystal hollow ZSM-5 molecular sieve to obtain a phosphorus-containing single crystal hollow ZSM-5 molecular sieve. The method of introducing phosphorus can be carried out according to existing methods, for example, phosphorus can be introduced into the H-type single crystal hollow ZSM-5 molecular sieve by an impregnation method, which generally includes the steps of contacting the H-type single crystal hollow ZSM-5 molecular sieve with an impregnation solution, drying, and roasting. The impregnation solution can be a phosphoric acid solution, an ammonium phosphate solution, a diammonium hydrogen phosphate solution or an ammonium dihydrogen phosphate solution or a mixture of these solutions. The drying and roasting methods can be carried out according to existing methods, for example, drying, air flow drying, and rotary drying; and roasting can be carried out at a temperature of 450-600°C for 1-6 hours.

[0092] According to a third aspect of the present invention, the present invention relates to applications of a single crystal hollow ZSM-5 molecular sieve provided according to the first aspect of the present invention, particularly in the fields of petrochemicals and / or fine chemicals.

[0093] According to an embodiment of the third aspect, the single crystal hollow ZSM-5 molecular sieve according to the present invention can be applied to the adsorption separation or catalytic cracking / cracking of hydrocarbon compounds. When the single crystal hollow ZSM-5 molecular sieve is used in the catalytic cracking reaction of hydrocarbon compounds, it is possible to obtain a higher light olefin (ethylene and propylene) yield and BTX yield, as well as a higher ethylene / propylene ratio. Therefore, the single crystal hollow ZSM-5 molecular sieve according to the present invention has good industrial application value.

[0094] According to an embodiment of the third aspect, the single crystal hollow ZSM-5 molecular sieve is used for the catalytic cracking of hydrocarbon oil, which includes contacting the hydrocarbon oil with the single crystal hollow ZSM-5 molecular sieve to carry out a catalytic cracking reaction step. According to a preferred embodiment, the single crystal hollow ZSM-5 molecular sieve is a hydrogen-type molecular sieve. According to a preferred embodiment, the single crystal hollow ZSM-5 molecular sieve contains phosphorus, which is called a phosphorus-containing single crystal hollow ZSM-5 molecular sieve, wherein the phosphorus content can be, for example, 0.5-10% by weight, such as 6% by weight, 7% by weight, 8% by weight or 9% by weight, relative to the weight of the molecular sieve.

[0095] Since the single crystal hollow ZSM-5 molecular sieve according to the present invention has a double-layer closed cavity and an epitaxially grown nanorod shell, the morphological characteristics of this nanorod shell have the characteristics of "short straight pores and long sinusoidal pores", the number of straight pore openings is increased (further improving the accessibility of the active center), the number of pore cross cavities is increased, that is, the proportion of acid sites at the cross pores is increased, and the dual modulation of the molecular sieve pore structure and acid properties is achieved. Moreover, the molecular sieve wall layer has a rich pore structure, including a microporous structure, a mesoporous structure, and a macroporous structure. Therefore, the single crystal hollow ZSM-5 molecular sieve according to the present invention can provide a multi-directional diffusion path for macromolecular reactants, improve the accessibility of the active center of the molecular sieve, and have excellent catalytic performance. Since the single crystal hollow ZSM-5 molecular sieve has the accessibility of the active site of the molecular sieve, it has an improved ability to catalyze the cracking reaction of macromolecular hydrocarbon compounds. For example, when it is used in the catalytic cracking reaction of macromolecular hydrocarbon compounds, it can have a higher yield of light olefins and BTX yield, as well as a higher ethylene / propylene ratio.

[0096] The single crystal hollow ZSM-5 molecular sieve synthesis method provided by the second aspect of the present invention can obtain the single crystal hollow ZSM-5 molecular sieve according to the present invention. Moreover, in the single crystal hollow ZSM-5 molecular sieve synthesis method according to the present invention, there is no need to use a large amount of organic template agent, making the synthesis method environmentally friendly.

[0097] For the present invention, the total specific surface area, mesopore specific surface area, micropore specific surface area and pore volume of the single crystal hollow ZSM-5 molecular sieve of the present invention are measured by low-temperature nitrogen adsorption method, wherein the instrument used in the low-temperature nitrogen adsorption analysis is ASAP2420 physical adsorption instrument (from American Mac Instrument Company), and the following experimental method is used: the first step is to pretreat the sample: weigh a certain amount of sample and put it into a sample tube that has been measured with a blank, put it into a degassing treatment unit, and degas for 6 hours at a furnace temperature of 300°C and a vacuum degree of less than 1.33 Pa. The second step is to measure the sample: put the pretreated sample tube into the measurement unit, fill the Dewar flask with liquid nitrogen, input the analysis file to start the measurement, and the measurement process is to use the static capacity method to measure the adsorption isotherm, calculate the total pore volume according to the adsorption amount of P / P0=0.98, calculate the pore size distribution according to the BJH method, obtain the mesopore volume, and calculate the specific surface area using the BET formula. Test conditions: Samples were vacuum degassed at 100°C and 300°C for 0.5 hours and 6 hours, respectively. N2 adsorption-desorption tests were then conducted at 77.4K. The adsorption and desorption of nitrogen from the purified samples were measured under different pressure ratios, and N2 adsorption-desorption isotherms were obtained. The BET specific surface area was calculated using the BET formula, the micropore area was calculated using a t-plot, and the pore size distribution was calculated using the BJH method.

[0098] The acidity of the molecular sieve according to the present invention is obtained using the NH3-TPD method. The acidity of the molecular sieve is determined using an AutochemII 2920 temperature-programmed desorber from Mack, USA. Specific testing method: 0.2 g of a 20-40 mesh molecular sieve is weighed in a sample tube and placed in a heating furnace. Using He as the carrier gas at a flow rate of 25 ml / min, the temperature is raised to 600°C at 20°C / min and purged for 90 minutes to remove impurities adsorbed on the molecular sieve surface. The temperature is then lowered to 150°C and maintained at this temperature for 5 minutes. NH3-He gas (10% by mass NH3 and 90% by mass He) is introduced into the system for 60 minutes of adsorption, followed by a He purge for 120 minutes until the baseline is stable to desorb physically adsorbed ammonia. The temperature is then programmed to 600°C at a temperature ramp rate of 10°C / min for desorption, held for 60 minutes, and desorption is completed. TCD is used to detect changes in gas composition, and the instrument automatically integrates to obtain the total acidity.

[0099] Fourier transform diffraction spectrum, measuring instrument and method: The electron microscope model is JEM-ARM200F, and the electron diffraction pattern of the electron microscope is directly photographed.

[0100] According to the fourth aspect of the present invention, the present invention also relates to a catalyst containing the single crystal hollow ZSM-5 molecular sieve according to the first aspect or the single crystal hollow ZSM-5 molecular sieve obtained by the method according to the second aspect, especially a catalytic cracking catalyst.

[0101] According to the first series of schemes of the fourth aspect of the present invention, the present invention provides a catalytic cracking catalyst, which contains a single crystal hollow ZSM-5 molecular sieve, a Y-type molecular sieve and a carrier; preferably, the content of the single crystal hollow ZSM-5 molecular sieve is 20-50 weight%, the content of the Y-type molecular sieve is 10-30 weight%, and the content of the carrier is 20-70 weight%.

[0102] According to a preferred embodiment of the first series of solutions, the Y-type molecular sieve is a rare earth Y-type molecular sieve and / or an ultrastable Y-type molecular sieve, for example, a Y-type molecular sieve that has been hydrothermally ultrastable and / or vapor-phase ultrastable. Preferably, the rare earth (RE) content of the Y-type molecular sieve, calculated as RE2O3 oxide, relative to the total weight of the Y-type molecular sieve is 2-25%. In the present invention, the rare earth content can be determined by XRF fluorescence detection. The rare earth element is preferably one or both of lanthanum and cerium.

[0103] The main active component in the catalyst includes a single crystal hollow ZSM-5 molecular sieve according to the present invention, which has a double-layer cavity and an epitaxially grown nanorod shell. The nanorod shell grows along the ac axis direction (010 plane). The morphology of this nanorod shell has the characteristics of "short straight channels and long sinusoidal channels", which increases the number of straight channel openings (further improving the accessibility of active centers). The increase in the number of channel intersection cavities, that is, the increase in the proportion of acidic sites at the intersection channels, achieves dual modulation of the molecular sieve pore structure and acid properties, so that the obtained catalyst can be used in the catalytic cracking reaction of large molecular hydrocarbon compounds, with higher ethylene yield and BTX yield, as well as a higher ethylene / propylene ratio.

[0104] According to one embodiment of the first series of schemes, the single crystal hollow ZSM-5 molecular sieve contains phosphorus and has a phosphorus / aluminum molar ratio of greater than 1. After hydrothermal treatment at 800°C for 17 hours, the crystallization retention rate is greater than or equal to 90%, for example, 90-98% or 90.2-95%, and / or the acid retention rate is greater than or equal to 30%, for example, 30-40% or 30.5-35%.

[0105] According to one embodiment of the first series of schemes, the single crystal hollow ZSM-5 molecular sieve does not contain phosphorus or the phosphorus / aluminum molar ratio is less than 1. When the single crystal hollow ZSM-5 molecular sieve is modified under the condition of a phosphorus / aluminum molar ratio of 1, the obtained molecular sieve is hydrothermally treated at 800°C for 17 hours, and the crystal retention is greater than or equal to 90%, for example, 90-98% or 90.2-95%, and / or the acid retention is greater than or equal to 30%, for example, 30-40% or 30.5-35%. This indicates that the single crystal hollow ZSM-5 molecular sieve has good hydrothermal stability. The phosphorus / aluminum molar ratio of the single crystal hollow ZSM-5 molecular sieve can be obtained by XRF fluorescence detection.

[0106] According to one embodiment of the first series of solutions, the Y-type molecular sieve contains rare earths and may contain or be free of phosphorus. The rare earth content of the Y-type molecular sieve, calculated as RE2O3, is 2-25% by weight, for example, 8-15% by weight. The phosphorus content, calculated as P2O5, may be 0-10% by weight, for example, 2-9% by weight, relative to the total weight of the Y-type molecular sieve.

[0107] According to one embodiment of the first series of schemes, the Y-type molecular sieve is an ultrastable Y-type molecular sieve and / or a rare earth Y-type molecular sieve. The ultrastable Y-type molecular sieve can be a Y-type molecular sieve that has been subjected to hydrothermal ultrastable and / or gas-phase ultrastable treatment, for example, a hydrothermal ultrastable Y-type molecular sieve, a gas-phase ultrastable Y-type molecular sieve, or a Y-type molecular sieve that has been subjected to both hydrothermal ultrastable and gas-phase ultrastable treatments.

[0108] The "hydrothermal ultra-stabilization" refers to treating the Y molecular sieve in the presence of water vapor to dealuminate the molecular sieve so as to increase the silicon-to-aluminum ratio of the Y molecular sieve. The "gas-phase ultra-stabilization" refers to treating the Y molecular sieve in the presence of silicon tetrachloride to dealuminate and siliconize the molecular sieve so as to increase the silicon-to-aluminum ratio of the molecular sieve. According to one embodiment, a Y molecular sieve that has undergone hydrothermal ultra-stabilization and gas-phase ultra-stabilization is obtained as follows: the Y molecular sieve is usually first subjected to a certain degree of hydrothermal ultra-stabilization treatment, and then subjected to gas-phase ultra-stabilization treatment. Since the gas-phase ultra-stabilization method and the hydrothermal ultra-stabilization method are well known to those skilled in the art, they will not be repeated here.

[0109] The gas-phase ultrastable molecular sieve is selected from one or more of HSY-4, HSY-12, SCY-4, and SCY-12. The hydrothermal ultrastable molecular sieve is selected from one or more of DASY-2.0, DSCY-2, RSCY-12, RSCY, SOY-2, SOY-8, and SOY-12. The RSCY molecular sieve typically has a rare earth content (calculated as RE2O3) of 16% to 18% by weight. The rare earth Y molecular sieve can be selected from one or more of REY and HRY.

[0110] According to one embodiment of the first series of schemes, the carrier is selected from one or more of natural clay, alumina carrier, silica carrier, aluminum phosphate carrier and silica-alumina carrier.

[0111] According to a preferred 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 aluminum sol, acidified pseudo-boehmite, hydrated alumina and activated alumina; the aluminum phosphate carrier is phosphate aluminum gel; the silica aluminum oxide carrier is one or more of solid silica aluminum material, silica aluminum sol and silica aluminum gel.

[0112] According to one embodiment of the first series of schemes, based on the dry mass of the catalytic cracking catalyst, the content of sodium oxide in the catalytic cracking catalyst is preferably 0.15 wt% or less.

[0113] According to a preferred embodiment of the first series of schemes, the carrier comprises a silicon oxide carrier; preferably, the content of the silicon oxide carrier in terms of SiO2 is 1-20 wt% based on the dry mass of the catalyst.

[0114] According to one embodiment of the first series of schemes, based on the dry basis mass of the catalytic cracking catalyst, the content of the single crystal hollow ZSM-5 molecular sieve is 20-50 weight%, for example, 25-45 weight%, or 30-40 weight%, and / or the content of the Y-type molecular sieve is 10-30 weight%, preferably 10-25 weight%, for example, 12-23 weight%, and the content of the carrier is 20-70 weight%, preferably 30-60 weight%, for example, 40-50 weight%.

[0115] According to one embodiment of the first series of schemes, the carrier includes clay, aluminum sol, pseudo-boehmite and silica sol. According to a preferred embodiment, in the catalytic cracking catalyst, the content of the single crystal hollow ZSM-5 molecular sieve is 20-50% by weight, for example, 25-45% by weight or 30-40% by weight, the content of the Y-type molecular sieve is 10-30% by weight, for example, 10-25% by weight, the content of the silica sol is 2-20% by weight, for example, 3-15% by weight or 3-10% by weight, calculated as SiO2, the content of the pseudo-boehmite (abbreviated as aluminum sol) is 5-35% by weight, for example, 10-25% by weight, calculated as Al2O3, the content of the aluminum sol is 3-30% by weight, for example, 5-20% by weight, calculated as Al2O3, and the content of the clay is 15-50% by weight, for example, 20-40% by weight.

[0116] According to one embodiment of the first series of schemes, based on the dry mass of the catalyst, the catalytic cracking catalyst contains 20-50% by weight, preferably 25-45% by weight, more preferably 30-40% by weight of single crystal hollow ZSM-5 molecular sieve, 10-30% by weight, preferably 10-20% by weight of Y-type molecular sieve, 20-50% by weight, preferably 20-40% by weight of clay, 10-30% by weight, preferably 10-20% by weight of acidified pseudo-boehmite, 3-20% by weight, preferably 5-18% by weight of aluminum sol and 2-15% by weight, preferably 3-10% by weight of silica sol.

[0117] According to the second series of solutions of the fourth aspect of the present invention, the present invention provides a catalytic cracking catalyst comprising a single-crystal hollow ZSM-5 molecular sieve, a Y-type molecular sieve, a multi-level pore MFI molecular sieve, a nanomolecular sieve, and a support. The catalyst can efficiently promote the conversion of heavy oil and, when used in the catalytic cracking process of heavy oil, can effectively increase the yield of light olefins (ethylene, propylene, and C4 olefins) and BTX.

[0118] According to an embodiment of the second series of schemes of the fourth aspect above, in the catalytic cracking catalyst, based on the dry weight of the catalytic cracking catalyst, the content of the single crystal hollow ZSM-5 molecular sieve is 10-30% by weight, preferably 12-28% by weight, preferably 15-25% by weight, the content of the Y-type molecular sieve is 5-20% by weight, preferably 10-15% by weight, the content of the multi-level pore MFI molecular sieve is 5-20% by weight, preferably 10-15% by weight, the content of the nano molecular sieve is 3-10% by weight, preferably 5-8% by weight, and the content of the The content of the carrier is 20-70% by weight, preferably 30-60% by weight; the single crystal hollow ZSM-5 molecular sieve has a double-layer closed cavity and an epitaxially grown nanorod shell, the nanorod shell grows along the ac axis, and the entire particle has a single crystal structure; preferably, the rare earth content of the Y-type molecular sieve is 0-25% in terms of RE2O3 (rare earth oxide), relative to the total dry weight of the Y-type molecular sieve; the nano molecular sieve has the following nano characteristics: an average grain size of 50nm-500nm, and a pore size of 0.56-0.75nm.

[0119] According to one embodiment of the second series of schemes of the fourth aspect above, the catalytic cracking catalyst comprises a single crystal hollow ZSM-5 molecular sieve, a Y-type molecular sieve, a multi-level pore MFI molecular sieve, a nanomolecular sieve, clay, pseudo-boehmite (abbreviated as diaspore), aluminum sol and silica sol. Based on the dry weight of the catalytic cracking catalyst, the catalytic cracking catalyst contains 10-30 weight% and preferably 15-25 weight% of the single crystal hollow ZSM-5 molecular sieve on a dry basis, 10-20 weight% and preferably 13-18 weight% of the Y-type molecular sieve on a dry basis, and 5-20 weight% and preferably 10-25 weight% of the Y-type molecular sieve on a dry basis. 15 wt% of multi-level pore MFI molecular sieve, 3-10 wt% on a dry basis, for example 5-10 wt% of nano molecular sieve, 10-55 wt% on a dry basis, for example 20-50 wt% of clay, 10-30 wt% on a dry basis, for example 10-20 wt% of pseudo-boehmite, 3-20 wt% on a Al2O3 basis, for example 8-15 wt% of aluminum sol and 2-15 wt% on a SiO2 basis, for example 2-8 wt% of silica sol, the pseudo-boehmite is preferably acidified pseudo-boehmite, and the acidification is carried out by a method well known to those skilled in the art.

[0120] The single crystal hollow ZSM-5 molecular sieve can be a hydrogen-type single crystal hollow ZSM-5 molecular sieve or a phosphorus-containing single crystal hollow ZSM-5 molecular sieve. The phosphorus content of the phosphorus-containing single crystal hollow ZSM-5 molecular sieve can be greater than 0 to 15% by weight in terms of P2O5, for example, 0.5-10% by weight. Preferably, the phosphorus / aluminum molar ratio (i.e., the molar ratio of phosphorus / aluminum) of the phosphorus-containing single crystal hollow ZSM-5 molecular sieve is referred to as phosphorus / aluminum ratio and is 0.8-1.2, for example, greater than 1 and less than 1.2. The phosphorus / aluminum molar ratio of the single crystal hollow ZSM-5 molecular sieve can be obtained by XRF fluorescence detection.

[0121] When the single crystal hollow ZSM-5 molecular sieve contains phosphorus or phosphorus is introduced so that the phosphorus / aluminum molar ratio is 1 or greater, after hydrothermal treatment at 800° C. for 17 hours, the crystal retention is greater than or equal to 90% and / or the acid retention is greater than or equal to 30%. When the single crystal hollow ZSM-5 molecular sieve does not contain phosphorus or has a phosphorus / aluminum molar ratio of less than 1, the molecular sieve has the following properties: after hydrothermal treatment at 800° C. for 17 hours, the molecular sieve having a phosphorus / aluminum molar ratio of 1 obtained by introducing phosphorus into the single crystal hollow ZSM-5 molecular sieve that does not contain phosphorus or has a phosphorus / aluminum molar ratio of less than 1 has a crystal retention of greater than or equal to 90% and / or an acid retention of greater than or equal to 30% compared to the molecular sieve having a phosphorus / aluminum molar ratio of 1 before the hydrothermal treatment.

[0122] According to one embodiment of the second series of solutions of the fourth aspect, the mesopore volume of the multi-level pore MFI molecular sieve accounts for 40-70% of the total pore volume, preferably 50-60%. The multi-level pore MFI molecular sieve can be commercially available or prepared according to existing methods, such as the method disclosed in patent CN114715911A, for example, according to the methods disclosed in the examples or claims of the patent.

[0123] According to one embodiment of the second series of schemes of the fourth aspect, based on the dry weight of the catalytic cracking catalyst, the content of sodium oxide in the catalytic cracking catalyst is preferably 0.15 wt% or less.

[0124] According to one embodiment of the above-mentioned second series of schemes, the nanomolecular sieve is a molecular sieve with a pore size of 0.56-0.75 nm, which can be selected from one or more molecular sieves having an AET, AFR, AFS, AFI, BEA, BOG, CFI, CON, GME, IFR, ISV, LTL, MEI, MOR, OFF or SAO structure; the nanomolecular sieve is preferably selected from at least one of Beta, SAPO-5, SAPO-40, SSZ-13, CIT-1, ITQ-7, ZSM-18, mordenite and gmelinite.

[0125] According to one embodiment of the second series of solutions, the Y-type molecular sieve has a rare earth content of 0-25% by weight, preferably 2-15% by weight, calculated as RE2O3 oxide. The rare earth element is preferably selected from one or both of lanthanum and cerium. In the present invention, the rare earth content can be determined by XRF fluorescence detection.

[0126] Preferably, the Y-type molecular sieve contains rare earth and may or may not contain phosphorus. The rare earth content in the Y-type molecular sieve calculated as RE2O3 is 0-25% by weight, and the phosphorus content calculated as P2O5 may be 0-10% by weight.

[0127] The Y-type molecular sieve can be a conventional Y-type molecular sieve and / or an ultrastable Y-type molecular sieve. The ultrastable Y-type molecular sieve is preferably a Y-type molecular sieve that is hydrothermally ultrastable and / or gas-phase ultrastable, for example, it can be a Y-type molecular sieve that is only hydrothermally ultrastable, a Y-type molecular sieve that is only gas-phase ultrastable, or a Y-type molecular sieve that is hydrothermally ultrastable and gas-phase ultrastable. The conventional Y-type molecular sieve can be a rare earth-containing Y-type molecular sieve, the rare earth-containing Y-type molecular sieve being one or more of a REY molecular sieve and a HRY molecular sieve, the hydrothermal ultrastable Y-type molecular sieve being, for example, a DASY molecular sieve, a phosphorus-containing DASY molecular sieve and / or an RSCY molecular sieve, and the gas-phase ultrastable Y-type molecular sieve being, for example, a USY molecular sieve, a phosphorus-containing USY molecular sieve and / or an SCY molecular sieve.

[0128] According to a preferred embodiment of the second series of schemes, the Y-type molecular sieve is a rare earth Y-type molecular sieve and / or an ultra-stable Y-type molecular sieve containing rare earth; preferably, the gas-phase ultra-stable Y-type molecular sieve containing rare earth is, for example, one or more of HSY-4, HSY-12, SCY-4, and SCY-12, and / or the hydrothermal ultra-stable Y-type molecular sieve containing rare earth is, for example, one or more of DASY-2.0, DSCY-2, RSCY-12, RSCY (the rare earth content calculated as RE2O3 is, for example, 16% to 18% by weight), SOY-2, SOY-8, and SOY-12. The rare earth Y-type molecular sieve is, for example, one or more of REY and HRY molecular sieves.

[0129] According to a preferred embodiment of the above-mentioned second series of schemes, the Y-type molecular sieve is 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.

[0130] According to a preferred embodiment of the second series of schemes, the carrier is selected from one or more of natural clay, alumina carrier, silica carrier, aluminum phosphate carrier and silica-alumina carrier.

[0131] According to a preferred implementation manner of the above-mentioned second series of schemes, 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 aluminum sol, acidified pseudo-boehmite, hydrated alumina and activated alumina; the aluminum phosphate carrier is phosphate aluminum gel; the silica aluminum oxide carrier is selected from one or more of solid silica aluminum material, silica aluminum sol and silica aluminum gel.

[0132] According to a preferred embodiment of the second series of schemes, the carrier comprises a silica carrier; based on the dry weight of the catalyst, the content of the silica carrier in terms of SiO2 is 1-20 wt%, for example 5-15 wt%.

[0133] According to a preferred embodiment of the above-mentioned second series of schemes, based on the dry weight of the catalytic cracking catalyst, the content of the single crystal hollow ZSM-5 molecular sieve is 10-30% by weight, preferably 15-25% by weight, more preferably 18-22% by weight, the content of the Y-type molecular sieve is 10-20% by weight, preferably 13-18% by weight, the content of the multi-level pore MFI molecular sieve is 5-20% by weight, preferably 10-15% by weight, the content of the nano molecular sieve is 5-10% by weight, preferably 6-8% by weight, and the content of the carrier is 20-65% by weight, for example 25-60% by weight or 30-55% by weight.

[0134] According to a fifth aspect of the present invention, the present invention also relates to a method for preparing the catalytic cracking catalyst according to the fourth aspect of the present invention.

[0135] According to the first series of schemes of the fifth aspect above, the present invention also provides a method for preparing a catalytic cracking catalyst according to the first series of schemes of the fourth aspect of the present invention, the method comprising: spray drying and optionally calcining a slurry containing a carrier, a single crystal hollow ZSM-5 molecular sieve, a Y-type molecular sieve and water, wherein the single crystal hollow ZSM-5 molecular sieve has a double-layer closed cavity and an epitaxially grown nanorod shell, and the average grain size of the single crystal hollow ZSM-5 molecular sieve is preferably 0.8-3.5 μm; the nanorods of the single crystal hollow ZSM-5 molecular sieve grow along the ac axis direction, and the entire particle has a single crystal structure.

[0136] According to one embodiment of the first series of solutions of the fifth aspect, the method comprises: mixing and slurrying a support, a single crystal hollow ZSM-5 molecular sieve, a Y-type molecular sieve, and water to form a slurry comprising the support, the single crystal hollow ZSM-5 molecular sieve, the Y-type molecular sieve, and water; and then spray drying the mixture to form catalyst particles. The mixing and slurrying method is well known to those skilled in the art.

[0137] The carrier is selected from one or more of clay, alumina, silica, aluminum phosphate, and silica-alumina oxide carriers. The silica carrier is, for example, silica sol, which can be one or more of neutral silica sol, acidic silica sol, or alkaline silica sol. The alumina carrier is, for example, one or more of aluminum sol, acidified pseudo-boehmite, hydrated alumina, and activated alumina. The aluminum phosphate carrier is phosphate aluminum gel; the silica-alumina oxide carrier is selected from one or more of solid silica-alumina materials, silica-alumina sol, and silica-alumina gel. The clay is, for example, one or more of kaolin, halloysite, montmorillonite, diatomaceous earth, and terpentine.

[0138] According to an embodiment of the first series of schemes of the fifth aspect above, the formed slurry containing the carrier, the single crystal hollow ZSM-5 molecular sieve, the Y-type molecular sieve and water is spray dried and calcined. Spray drying can form the catalyst while drying the material. Spray drying and calcination can be carried out by spray drying and calcination methods conventionally used by those skilled in the art. According to a preferred embodiment, the calcination temperature can be, for example, 450-600° C., and the calcination time can be, for example, 1-5 hours.

[0139] According to one embodiment of the first series of solutions of the fifth aspect, in the method for preparing a catalytic cracking catalyst, the catalyst particles obtained by spray drying may be further subjected to ammonium exchange to reduce the sodium oxide content in the catalyst. The ammonium exchange may be performed before or after calcination.

[0140] According to a preferred embodiment of the first series of schemes of the fifth aspect above, the method further comprises: mixing the catalyst particles obtained by spray drying, ammonium salt and water in a mass ratio of 1: (0.1-1): (5-15) for ammonium exchange, which is referred to as the second ammonium exchange, and optional washing; preferably, the conditions of the second ammonium exchange include: a temperature of 50-100°C, for example, 60-80°C, and a time of 0.5-2 hours, for example, 1-1.5 hours; the ammonium salt can be selected from one or more of ammonium chloride, ammonium sulfate and ammonium nitrate. The second ammonium exchange can be carried out once or multiple times. The catalyst after ammonium exchange is optionally calcined. Preferably, the second ammonium exchange causes the sodium oxide content in the obtained catalytic cracking catalyst to be no higher than 0.15% by weight.

[0141] According to the second series of schemes of the above-mentioned fifth aspect, the present invention also provides a method for preparing a catalytic cracking catalyst according to the second series of schemes of the fourth aspect of the present invention, the method comprising: spray drying and calcining a slurry containing a carrier, a single crystal hollow ZSM-5 molecular sieve, a Y-type molecular sieve, a multi-level pore MFI molecular sieve, a nanomolecular sieve and water.

[0142] According to one embodiment of the second series of schemes of the fifth aspect, the method comprises: mixing a carrier, a single crystal hollow ZSM-5 molecular sieve, a Y-type molecular sieve, a multi-level pore MFI molecular sieve, a nanomolecular sieve, and water; beating the carrier, the single crystal hollow ZSM-5 molecular sieve, the Y-type molecular sieve, the multi-level pore MFI molecular sieve, the nanomolecular sieve, and water to form a slurry; and then spray-drying the slurry to form catalyst particles. The above-mentioned mixing, beating, and spray-drying methods are well known to those skilled in the art, and the present invention has no special requirements for these methods.

[0143] The carrier includes, for example, one or more of clay, aluminum oxide, silicon oxide, aluminum phosphate, and silicon aluminum oxide. The silicon oxide carrier, for example, is silica sol, which can be one or more of neutral silica sol, acidic silica sol, or alkaline silica sol. The aluminum oxide carrier, for example, is one or more of aluminum sol, acidified pseudo-boehmite, hydrated alumina, and activated alumina. The aluminum phosphate carrier is aluminum phosphate gel; the silicon aluminum oxide carrier is selected from one or more of solid silicon aluminum materials, silicon aluminum sol, and silicon aluminum gel. The clay, for example, is one or more of kaolin, halloysite, montmorillonite, diatomaceous earth, and terpentine.

[0144] According to an embodiment of the second series of schemes of the fifth aspect above, the formed slurry containing a carrier, a single crystal hollow ZSM-5 molecular sieve, a Y-type molecular sieve, a multi-level pore MFI molecular sieve, a nanomolecular sieve and water is spray dried and calcined. Spray drying can form the catalyst while drying the material. Spray drying and calcination can be implemented by spray drying and calcination methods conventionally used by those skilled in the art. According to a preferred embodiment, the calcination temperature can be, for example, 450-600° C., and the calcination time can be, for example, 1-5 hours.

[0145] According to one embodiment of the second series of solutions of the fifth aspect, in the method for preparing a catalytic cracking catalyst, the catalyst particles obtained by spray drying may be further subjected to ammonium exchange to reduce the sodium oxide content in the catalyst. The ammonium exchange may be performed before or after calcination.

[0146] According to one embodiment of the second series of schemes of the fifth aspect above, the method for preparing a catalytic cracking catalyst provided by the present invention further includes: mixing the catalyst particles obtained by the spray drying, ammonium salt and water in a weight ratio of 1: (0.1-1): (5-15) and performing ammonium exchange, referred to as the second ammonium exchange, and optional washing. Preferably, the conditions for the second ammonium exchange include: a temperature of 50-100°C, such as 60-80°C, and a time of 0.5-2 hours, such as 1-1.5 hours; the ammonium salt can be selected from one or more of ammonium chloride, ammonium sulfate and ammonium nitrate. The second ammonium exchange can be carried out once or multiple times. The catalyst after ammonium exchange is optionally calcined. Preferably, the second ammonium exchange causes the sodium oxide content in the obtained catalytic cracking catalyst to be no higher than 0.15% by weight.

[0147] According to a sixth aspect of the present invention, the present invention also provides use of the catalytic cracking catalyst according to the present invention for catalytic cracking of heavy oil to increase production of light olefins (ethylene, propylene, etc.) and BTX.

[0148] According to the first series of schemes of the sixth aspect, the present invention provides a use of a catalytic cracking catalyst according to the first series of schemes of the fourth aspect for increasing the production of ethylene and BTX in catalytic cracking of heavy oil, wherein the catalytic cracking catalyst contains the single crystal hollow ZSM-5 molecular sieve, Y-type molecular sieve and a carrier according to the present invention; preferably, the catalytic cracking catalyst is contacted with heavy oil in a fluidized bed reactor to carry out a catalytic cracking reaction.

[0149] According to a preferred embodiment of the first series of schemes of the sixth aspect, the catalytic cracking reaction temperature is 550-650°C, preferably 580-620°C, the catalyst-oil ratio by weight is 5-30, preferably 8-20, and the weight hourly space velocity is 5-30h -1 , for example 8-20h -1 .

[0150] According to a preferred embodiment of the first series of schemes of the sixth aspect, the catalytic cracking catalyst comprises a single crystal hollow ZSM-5 molecular sieve with a nanorod shell layer, an ultra-stable Y-type molecular sieve and a carrier according to the present invention. The multidimensional pore structure and a large number of active centers of the single crystal hollow ZSM-5 molecular sieve enable the catalyst to have better accessibility to active centers and diffusion performance for large reaction molecules, allowing for efficient promotion of heavy oil conversion. Using this catalyst in the catalytic cracking process of heavy oil can effectively increase the yield of ethylene and BTX.

[0151] The catalytic cracking method provided by the present invention can promote the cracking of heavy oil, reduce the yields of diesel and heavy oil, and significantly improve the yields of ethylene and BTX.

[0152] According to the second series of schemes of the sixth aspect, the present invention relates to a catalytic cracking catalyst according to the second series of schemes of the fourth aspect of the present invention for increasing the production of light olefins and BTX in catalytic cracking of heavy oil, preferably, the light olefins are selected from ethylene, propylene and C4 olefins.

[0153] According to one embodiment of the second series of schemes of the sixth aspect, the catalytic cracking is carried out in a fluidized bed reactor. Preferably, the reaction temperature of the catalytic cracking is 550-650°C, preferably 580-620°C, the catalyst-oil ratio by weight is 5-30, preferably 8-20, and the weight hourly space velocity is, for example, 5-30h -1 , for example 8-20h -1 .

[0154] Other features and advantages of the present invention will be described in detail in the following specific embodiments.

[0155] In the following examples and comparative examples, all raw materials used, unless otherwise specified, were commercially available. Kaolin was an industrial product from China Kaolin Corporation, with a solids content of 75% by weight; pseudo-boehmite was supplied by Shandong Aluminum Plant, with an alumina content of 65% by weight; alumina sol was supplied by the Qilu Branch of Sinopec Catalyst Co., Ltd., with an alumina content of 20% by weight; silica sol was supplied by Beijing Chemical Plant, with a silica content of 25% by weight (alkaline silica sol, pH 9.5); and concentrated hydrochloric acid was chemically pure and supplied by Beijing Chemical Plant. Y-type molecular sieves, designated RSCY-12 (rare earth content of 12% by weight, silicon / aluminum molar ratio (SiO2 / Al2O3) of 5.2, and relative crystallinity of 65%) or DSCY-2 (rare earth content of 2% by weight, silicon / aluminum molar ratio (SiO2 / Al2O3) of 5.2, and relative crystallinity of 67%), were supplied by the Qilu Branch of Sinopec Catalyst Co., Ltd. Hierarchical pore size MFI molecular sieve with a silicon-aluminum (SiO2 / Al2O3) molar ratio of 25, sold by Sinopec Catalyst Co., Ltd. Qilu Branch, has a P2O5 content of 6.5% by weight and is commercially available under the RMPZ designation. Beta molecular sieve, designated BETA-25-NKC, has a pore size of 0.59 nm and an average crystallite size of 200 nm and is sold by Tianjin Nanhua Catalyst Co., Ltd.

[0156] The total specific surface area and mesopore specific surface area of ​​the molecular sieve samples were determined using the BET adsorption full analysis method. Instrument: ASAP2420 adsorption instrument, Micromeritics, USA. Test conditions: Samples were vacuum degassed at 100°C and 300°C for 0.5 hours and 6 hours, respectively. N2 adsorption-desorption tests were performed at 77.4K. The adsorption and desorption amounts of nitrogen on the purified samples were measured under different specific pressures, and N2 adsorption-desorption isotherms were obtained. The BET specific surface area was calculated using the BET formula, the micropore area was calculated using a t-plot, and the pore size distribution was calculated using the BJH method.

[0157] The relative crystallinity of the molecular sieve samples was determined by X-ray diffraction using an Empyrean instrument. Test conditions included a tube voltage of 40 kV, a tube current of 40 mA, Cu target Kα radiation, a 2θ scanning range of 5°-35°, and a scanning rate of 2° / min.

[0158] The acid content of molecular sieves was determined using a Micromeritics Autochem II 2920 programmed temperature desorber. The test method: 0.2 g of 20-40 mesh molecular sieve was weighed into a sample tube and placed in a heating furnace. Using He as the carrier gas at a flow rate of 25 ml / min, the temperature was raised at 20°C / min to 600°C. The system was then purged for 90 minutes to remove impurities adsorbed on the molecular sieve surface. The temperature was then lowered to 150°C and held constant for 5 minutes. NH3-He gas (10% NH3 and 90% He by mass) was then introduced into the system for adsorption for 60 minutes. The system was then purged with He for 120 minutes until the baseline stabilized, thereby desorbing the physically adsorbed ammonia. The temperature was then programmed to 600°C at a rate of 10°C / min, held for 60 minutes, and desorption was completed. The gas composition changes were detected using a TCD, and the instrument automatically integrated the data to obtain the total acid content.

[0159] The room temperature involved in the following examples and comparative examples is 26°C.

[0160] Examples 1-4 are examples of preparing single crystal hollow ZSM-5 molecular sieves.

[0161] Example 1

[0162] Prepare seed solution:

[0163] (A1) 30.0 g of ethyl orthosilicate, 34.0 g of tetrapropylammonium hydroxide, and 44.2 g of deionized water were mixed and heated with stirring at 40° C. for 4 hours;

[0164] (A2) The mixture of sub-step (A1) was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and dynamically crystallized at 170° C. for 12 hours. After the crystallization was completed, the crystallized product was removed from the reactor and recorded as seed solution 1.

[0165] Preparation of single crystal hollow ZSM-5 molecular sieve:

[0166] (B1-1) Add 5.21 g of potassium hydroxide to 15.63 g of deionized water and stir well.

[0167] (B1-2) Add 1.8 g of aluminum sulfate 18hydrate to 16.2 g of deionized water and stir well.

[0168] (B1-3) Slowly adding 30.20 g of silica sol (sodium silica sol, 30 wt % silicon oxide content, 0.22 wt % sodium oxide content, pH 9.2) to the alkaline source solution of substep (B1-1) and stirring at room temperature for 30 minutes;

[0169] (B1-4) adding 214.47 g of deionized water to sub-step (B1-3), then adding the aluminum source solution from sub-step (B1-2) with stirring, and stirring at room temperature for 30 minutes to obtain a mixed solution;

[0170] (B2) adding 6.34 g of the seed solution 1 obtained in sub-step (A2) to the mixed solution obtained in sub-step (B1-4), and stirring at room temperature for 4 hours to obtain a mixed solution;

[0171] (B3) transferring the mixed solution obtained in substep (B2) to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and subjecting it to hydrothermal dynamic crystallization at 170° C. for 48 hours; filtering, washing, drying, and calcining the obtained product at 550° C. for 2 hours (the same below) to obtain molecular sieve M-1;

[0172] (B4) molecular sieve M-1 and a 0.6 mol / L sodium hydroxide solution were mixed uniformly, with the mass ratio of molecular sieve M-1 to sodium hydroxide solution being 1:10. The mixture was heated to 80° C. at a heating rate of 4° C. / min, stirred at the same temperature for 30 minutes, filtered, washed, and dried to obtain molecular sieve M-1-J.

[0173] (B5) Mix molecular sieve M-1-J: ammonium chloride: deionized water in a mass ratio of 1:1:10, stir and heat in a water bath at 80°C for 30 minutes, filter, wash and dry, then mix the dried solid: ammonium chloride: deionized water in a mass ratio of 1:0.5:10, perform a second ammonium exchange, filter, wash, dry, and calcine at 550°C for 2 hours to obtain a hydrogen-type single crystal hollow ZSM-5 molecular sieve, recorded as M-1-JH.

[0174] Figure 1 is a transmission electron microscope image of the single crystal hollow ZSM-5 molecular sieve M-1-JH, and Figure 2 is a Fourier transform diffraction spectrum of the single crystal hollow ZSM-5 molecular sieve. According to Figure 2, it can be seen that the single crystal hollow ZSM-5 molecular sieve has a single crystal structure.

[0175] Example 2

[0176] Prepare seed solution:

[0177] (A1) 54.8 g of ethyl orthosilicate, 29.7 g of tetrapropylammonium hydroxide, and 240.5 g of deionized water were mixed and heated with stirring at 40° C. for 4 hours;

[0178] (A2) The solution from sub-step (A1) was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and subjected to dynamic crystallization at 170° C. for 12 hours; the resulting crystallized product was designated as seed solution 2.

[0179] Preparation of single crystal hollow ZSM-5 molecular sieve:

[0180] (B1-1) Add 5.46 g of potassium hydroxide to 24.87 g of deionized water and stir to obtain an alkaline source solution;

[0181] (B1-2) Add 1.24 g of aluminum isopropoxide to 14.26 g of deionized water and stir to obtain an aluminum source solution;

[0182] (B1-3) Slowly adding 35.80 g of silica sol (silicon oxide content 30 wt %, same as Example 1) to the alkaline source solution of substep (B1-1) and stirring at room temperature for 30 minutes;

[0183] (B1-4) Add 181.37 g of deionized water to sub-step (B1-3), then add the aluminum source solution from sub-step (B1-2) with stirring, and stir at room temperature for 30 minutes;

[0184] (B2) adding 10.74 g of seed solution 2 to the solution of sub-step (B1-4) and stirring at room temperature for 4 hours;

[0185] (B3) transferring the mixed solution obtained in substep (B2) to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and subjecting it to hydrothermal dynamic crystallization at 170° C. for 48 hours; filtering, washing, drying, and calcining the obtained product to obtain molecular sieve M-2;

[0186] (B4) molecular sieve M-2 and a 0.4 mol / L sodium hydroxide solution were mixed uniformly, with the mass ratio of molecular sieve M-2 to the alkaline solution being 1:10. The mixture was heated to 80° C. at a heating rate of 4° C. / min, stirred at the same temperature for 30 minutes, filtered, washed, and dried to obtain molecular sieve M-2-J.

[0187] (B5) Molecular sieve M-2-J: ammonium chloride: deionized water were mixed in a mass ratio of 1:1:10, stirred and heated in a water bath at 80°C for 30 minutes, filtered, washed, and dried, and then the dried solid: ammonium chloride: deionized water were mixed in a mass ratio of 1:0.5:10, subjected to a second ammonium exchange, filtered, washed, dried, and calcined at 550°C for 2 hours to obtain a hydrogen-type single crystal hollow ZSM-5 molecular sieve, recorded as M-2-JH.

[0188] Example 3

[0189] Prepare seed solution:

[0190] (A1) 47.6 g of ethyl orthosilicate, 70.4 g of tetrapropylammonium hydroxide, and 187.6 g of deionized water were mixed and heated with stirring at 40° C. for 4 hours;

[0191] (A2) The solution from sub-step (A1) was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and dynamically crystallized at 170° C. for 12 hours. After the crystallization was completed, the solution was taken out and recorded as seed solution 3.

[0192] Preparation of single crystal hollow ZSM-5 molecular sieve:

[0193] (B1-1) Add 6.70 g of potassium hydroxide to 26.80 g of deionized water and stir well.

[0194] (B1-2) Add 1.20 g of sodium aluminate to 10.80 g of deionized water and stir well.

[0195] (B1-3) Slowly adding 56.80 g of silica sol (silicon oxide content 30 wt %, same as Example 1) to the alkali source solution of substep (B1-1) and stirring at room temperature for 30 minutes;

[0196] (B1-4) Add 363.30 g of deionized water to sub-step (B1-3), then add the aluminum source solution from sub-step (B1-2) while stirring, and stir at room temperature for 30 minutes;

[0197] (B2) adding 6.34 g of the seed solution 3 obtained in sub-step (A2) to the mixed solution obtained in sub-step (B1-4), and stirring at room temperature for 4 hours;

[0198] (B3) transferring the mixed solution obtained in substep (B2) to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and subjecting it to hydrothermal dynamic crystallization at 170° C. for 48 hours; filtering, washing, drying, and calcining the obtained product to obtain molecular sieve M-3;

[0199] (B4) mixing molecular sieve M-3 and a 1.0 mol / L sodium hydroxide solution in a mass ratio of 1:10, heating the mixture to 80° C. at a heating rate of 4° C. / min, stirring the mixture at the same temperature for 30 minutes, filtering, washing, and drying to obtain molecular sieve M-3-J;

[0200] (B5) Molecular sieve M-3-J: ammonium chloride: deionized water were mixed in a mass ratio of 1:1:10, stirred and heated in a water bath at 80°C for 30 minutes, filtered, washed, and dried, and then the dried solid: ammonium chloride: deionized water were mixed in a mass ratio of 1:0.5:10, subjected to a second ammonium exchange, filtered, washed, dried, and calcined at 550°C for 2 hours to obtain a hydrogen-type single crystal hollow ZSM-5 molecular sieve, recorded as M-3-JH.

[0201] Example 4

[0202] Prepare seed solution:

[0203] (A1) 43.5 g of ethyl orthosilicate, 35.9 g of tetrapropylammonium hydroxide, and 166.4 g of deionized water were mixed and heated with stirring at 40° C. for 4 hours;

[0204] (A2) The solution from sub-step (A1) was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and dynamically crystallized at 170° C. for 12 hours. After the crystallization was completed, the solution was taken out and recorded as seed solution 4.

[0205] Preparation of single crystal hollow ZSM-5 molecular sieve:

[0206] (B1-1) Add 6.50 g of potassium hydroxide to 15.17 g of deionized water and stir well.

[0207] (B1-2) Add 2.56 g of aluminum nitrate nonahydrate to 10.24 g of deionized water and stir well.

[0208] (B1-3) Slowly adding 64.9 g of silica sol (15 wt% silica content) to the alkali source solution of substep (B1-1) and stirring at room temperature for 30 minutes;

[0209] (B1-4) Add 225.39 g of deionized water to sub-step (B1-3), then add the aluminum source solution from sub-step (B1-2) with stirring, and stir at room temperature for 30 minutes;

[0210] (B2) adding 6.81 g of the seed solution 4 from sub-step (A2) to the solution from sub-step (B1-4) and stirring at room temperature for 4 hours;

[0211] (B3) transferring the mixed solution of substep (B2) to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and subjecting it to hydrothermal dynamic crystallization at 170° C. for 48 hours; filtering, washing, drying, and calcining the obtained product to obtain molecular sieve M-4;

[0212] (B4) molecular sieve M-4 and a 0.6 mol / L sodium hydroxide solution were mixed uniformly, with the mass ratio of molecular sieve M-4 to the sodium hydroxide solution being 1:10, and the mixture was heated to 80° C. at a heating rate of 4° C. / min, stirred at the same temperature for 30 minutes, filtered, washed, and dried to obtain molecular sieve M-4-J;

[0213] (B5) Molecular sieve M-4-J: ammonium chloride: deionized water were mixed in a mass ratio of 1:1:10, stirred and heated in a water bath at 80°C for 30 minutes, filtered, washed, and dried, and then the dried solid: ammonium chloride: deionized water were mixed in a mass ratio of 1:0.5:10, subjected to a second ammonium exchange, filtered, washed, dried, and calcined at 550°C for 2 hours to obtain a hydrogen-type single crystal hollow ZSM-5 molecular sieve, recorded as M-4-JH.

[0214] Comparative Example 1

[0215] Conventional ZSM-5 molecular sieve was purchased from Sinopec Catalyst Company Qilu Branch, with a silicon / aluminum molar ratio (SiO2 / Al2O3 of 25), and was denoted as DB1-H.

[0216] Comparative Example 2

[0217] (1) conventional ZSM-5 molecular sieve (the same as the ZSM-5 molecular sieve in Comparative Example 1) and a 0.2 mol / L sodium hydroxide solution were mixed uniformly, wherein the mass ratio of the ZSM-5 molecular sieve to the alkaline solution was 1:10, heated and stirred at 80°C for 30 minutes, filtered, washed, and dried;

[0218] (2) The alkali-treated conventional ZSM-molecular sieve, ammonium chloride, and deionized water were uniformly mixed in a mass ratio of 1:1:10, stirred and heated in a water bath at 80°C for 30 minutes, filtered, washed, and dried. The dried solid, ammonium chloride, and deionized water were then uniformly mixed in a mass ratio of 1:0.5:10, subjected to a second ammonium exchange, filtered, washed, dried, and calcined at 550°C for 2 hours to obtain a hydrogen-type molecular sieve DB2-H. The obtained hydrogen-type molecular sieve DB2-H does not have a cavity and does not have a rod-like structure.

[0219] Comparative Example 3

[0220] Conventional ZSM-5 molecular sieve was purchased from Sinopec Catalyst Company Qilu Branch, with a silicon / aluminum molar ratio (SiO2 / Al2O3) of 25, which is the same as the conventional ZSM-5 molecular sieve in Comparative Example 1.

[0221] (1) The conventional ZSM-5 molecular sieve and a 1.0 mol / L sodium hydroxide solution were mixed uniformly, wherein the mass ratio of the ZSM-5 molecular sieve to the alkaline solution was 1:10, heated and stirred at 80° C. for 30 minutes, filtered, washed, and dried;

[0222] (2) The alkali-treated ZSM-5 molecular sieve: ammonium chloride: deionized water were mixed uniformly in a mass ratio of 1:1:10, stirred and heated in a water bath at 80°C for 30 minutes, filtered, washed, and dried, and then the dried solid: ammonium chloride: deionized water were mixed uniformly in a mass ratio of 1:0.5:10, subjected to a second ammonium exchange, filtered, washed, dried, and calcined at 550°C for 2 hours to obtain a hydrogen-type molecular sieve DB3-H, which does not have a rod-like structure and does not have a cavity.

[0223] Table 1

[0224] The molecular sieve synthesis ratios in Table 1 are those of the product of step (B1-4). Seed size refers to the average size of the seed crystals, and its measurement method is as described above; the molecular sieve grain size refers to the average grain size of the final product, and its measurement method is as described above.

[0225] Molecular sieve evaluation

[0226] The molecular sieves prepared according to the embodiments and comparative examples were modified and calcined under a phosphorus / aluminum molar ratio of 1:1 (the method is as follows: the molecular sieve sample was evenly spread on a watch glass or a crucible, and the phosphorus-containing solution was slowly poured onto the molecular sieve sample so that the molecular sieve sample finally presented a "slurry state", stirred evenly and dried in an oven; then ground evenly and calcined at 550°C for 4 hours), aged and deactivated for 17 hours at 800°C and 100% water vapor atmosphere, tableted and sieved to obtain 40-60 mesh particles, and evaluated on a fixed bed microreactor FB. The model compounds were n-hexadecane and 1,3,5-triisopropylbenzene. The evaluation conditions were: reaction temperature 620°C, agent-oil ratio (mass ratio) of 0.75, oil feed rate 0.4 g / min, and oil feed time 300 seconds. The results are listed in Tables 2 and 3.

[0227] Table 2. n-Hexadecane conversion results

[0228] Table 3.1,3,5-Triisopropylbenzene conversion results

[0229] As can be seen from Tables 2 and 3 above, compared with the molecular sieves of the comparative example, the single crystal hollow ZSM-5 molecular sieve provided by the present invention has unique morphological characteristics and high diffusion properties. In the catalytic cracking reaction of long-chain alkanes (n-hexadecane) and macromolecular aromatics (1,3,5-triisopropylbenzene), it has higher diene yields and BTX yields, and has a higher ethylene / propylene ratio.

[0230] In Tables 2 and 3, "diene" refers to ethylene and propylene, and "BTX" refers to benzene, toluene, and xylene.

[0231] The following Examples 5-7 are used to illustrate the catalytic cracking catalysts according to the first series of schemes of the fourth aspect of the present invention.

[0232] The following Examples 5-7 and Comparative Example 4 are examples of preparing catalytic cracking catalysts.

[0233] Examples 5-7

[0234] Examples 5-7, respectively, used the single crystal hollow ZSM-5 molecular sieves prepared in Examples 1-3 to prepare catalytic cracking catalysts, with the catalysts numbered A1, A2, and A3. The single crystal hollow ZSM-5 molecular sieves prepared in Examples 1-3 were phosphorus-modified using an equal volume impregnation method at a phosphorus-to-aluminum ratio of 1:1, dried, and calcined prior to use. The resulting phosphorus-containing single crystal hollow ZSM-5 molecular sieves were designated M-1-J-HP, M-2-J-HP, and M-3-J-HP, respectively. The preparation method of the catalytic cracking catalyst comprises: (1) uniformly mixing pseudo-boehmite (abbreviated as diaspore) and water, adding concentrated hydrochloric acid with a concentration of 36% by mass under stirring, and the acid / aluminum weight ratio is 0.2, that is, the weight ratio of hydrochloric acid (calculated as hydrochloric acid with a HCl concentration of 36%) to pseudo-boehmite calculated as Al2O3; aging the obtained mixture at 70°C for 1.5 hours to obtain an aged pseudo-boehmite slurry; the aged pseudo-boehmite slurry has an alumina content of 12% by mass; (2) mixing the above-prepared single crystal hollow ZSM-5 molecular sieve, Y-type molecular sieve, aluminum The sol, silica sol, kaolin, the aged pseudo-boehmite slurry, and deionized water were uniformly mixed to form a slurry having a solid content of 30 wt %. The slurry was spray-dried to obtain catalyst microspheres. (3) The catalyst microspheres were calcined at 550° C. for 4 hours. (4) The calcined catalyst microspheres were ammonium exchanged at 80° C. for 1 hour in a mass ratio of catalyst microspheres: ammonium salt: H 2 O = 1:1:10, filtered, and the above-mentioned exchange and filtration process was repeated once. The catalyst was then dried, wherein the ammonium salt was ammonium chloride. The sodium oxide content of the obtained catalytic cracking catalyst was less than 0.15 wt %. The composition of the prepared catalyst is shown in Table 4.

[0235] Comparative Example 4

[0236] Comparative Example 4 illustrates the preparation of a catalytic cracking catalyst using the molecular sieve DB1-H provided in Comparative Example 1. Following the catalyst preparation method of Example 5, phosphorus was introduced into the molecular sieve DB1-H (denoted as DB1-HP), mixed with Y-type molecular sieve, pseudo-boehmite, silica sol, kaolin, water, and aluminum sol, and spray-dried to prepare a microsphere catalyst named DB2.

[0237] Comparative Example 5

[0238] A hollow molecular sieve was prepared according to Example 1 in Chinese patent CN116174024A, and then a catalyst was prepared according to the composition ratio and method of Example 5, and named DB3.

[0239] Comparative Example 6

[0240] The catalyst was prepared according to the method of Example 5, except that the contents of ZSM-5 molecular sieve and Y molecular sieve were different, as shown in Table 4. The catalyst was named DB4.

[0241] Table 4. Catalyst composition

[0242] In Table 4, ZSM-5 molecular sieve refers to the single crystal hollow ZSM-5 molecular sieve according to the present invention.

[0243] Performance Testing

[0244] The catalytic cracking catalysts prepared in Examples 5-7 and Comparative Examples 4-6 were aged at 800°C and 100% by volume water vapor for 17 hours, and then their catalytic cracking reaction performance was evaluated in a small fixed fluidized bed reactor. The evaluation conditions were a reaction temperature of 600°C, a catalyst-to-oil ratio of 10 by mass, and a weight hourly space velocity of 10 h. -1 The properties of heavy oil are shown in Table 5, and the reaction results are shown in Table 6.

[0245] Table 5. Heavy oil properties

[0246] Table 6. Catalytic performance evaluation results

[0247] As can be seen from Table 6, the catalytic cracking catalyst provided by the present invention has significantly higher ethylene yield and BTX yield.

[0248] The following Examples 8-12 are used to illustrate the catalytic cracking catalysts according to the second series of solutions of the fourth aspect of the present invention. The following Examples 8-12, Comparative Examples 7-10 and Reference Example 1 are examples of preparing catalytic cracking catalysts.

[0249] Examples 8-12

[0250] Catalysts were prepared using the single crystal hollow ZSM-5 molecular sieves prepared in Examples 1-3, and the catalyst numbers were A4, A5, and A6, respectively. The single crystal hollow ZSM-5 molecular sieves prepared in Examples 1-3 were phosphorus-modified using an equal volume impregnation method with a phosphorus-to-aluminum ratio of 1:1, dried, and calcined before use, and were designated M-1-J-HP, M-2-J-HP, and M-3-J-HP, respectively. The preparation method of the catalytic cracking catalyst comprises: (1) uniformly mixing pseudo-boehmite and water, adding concentrated hydrochloric acid with a concentration of 36% by weight while stirring, and an acid / aluminum weight ratio of 0.2 (i.e., the weight ratio of hydrochloric acid (calculated as hydrochloric acid with a HCl concentration of 36% by weight) to pseudo-boehmite calculated as Al2O3); aging the resulting mixture at 70°C for 1.5 hours to obtain an aged pseudo-boehmite slurry. The aged pseudo-boehmite slurry has an alumina content of 12 wt %; (2) the phosphorus-containing single crystal hollow ZSM-5 molecular sieve, Y-type molecular sieve, multi-level pore MFI molecular sieve, nanomolecular sieve, aluminum sol, silica sol, kaolin, the aged pseudo-boehmite slurry, and deionized water are uniformly mixed to form a slurry with a solid content of 30 wt %, and spray-dried to obtain catalyst microspheres; (3) the catalyst microspheres are calcined at 550° C. for 4 hours; (4) the calcined catalyst microspheres are exchanged at 80° C. for 1 hour in a weight ratio of catalyst microspheres: ammonium salt: H 2 O = 1:1:10, filtered, and the above exchange and filtration processes are repeated once, and then dried, wherein the ammonium salt is ammonium chloride. The sodium oxide content of the obtained catalytic cracking catalyst is less than 0.15 wt %. The composition of the prepared catalyst is shown in Table 7.

[0251] Comparative Example 7

[0252] Comparative Example 7 illustrates the preparation of a catalytic cracking catalyst using the molecular sieve DB1-H provided in Comparative Example 1. According to the catalyst preparation method of Example 8, phosphorus was introduced into the molecular sieve DB1-H at a phosphorus / aluminum molar ratio of 1 to obtain DB1-HP, and then a catalyst was prepared according to the method of Example 8, which was recorded as DB5.

[0253] Reference Example 1

[0254] The catalyst was prepared by the method of Example 8, except that the multi-level pore MFI molecular sieve and nanomolecular sieve were not used, but were replaced by an equal mass of single crystal hollow ZSM-5 molecular sieve, and RSCY-12 was used instead of the DSCY-2. The proportions are shown in Table 7. This catalyst was named BJ1.

[0255] Comparative Example 8

[0256] A catalyst was prepared according to the method of Example 8, except that the nano molecular sieve was not added and an equal mass of Y molecular sieve was used instead. The composition ratio is shown in Table 7. This catalyst was named DB6.

[0257] Comparative Example 9

[0258] A catalyst was prepared according to the method of Example 8, except that the multi-level pore MFI molecular sieve was not added, but an equal mass of single crystal hollow ZSM-5 molecular sieve was used instead. The composition ratio is shown in Table 7. This catalyst was named DB7.

[0259] Comparative Example 10

[0260] A catalyst was prepared according to the method of Example 8, without adding Y molecular sieve, multi-level pore size MFI molecular sieve and nano molecular sieve. The composition ratio is shown in Table 7. This catalyst was named DB8.

[0261] Table 7. Catalyst composition

[0262] *In Table 7, the first ZSM-5 molecular sieve refers to the single crystal hollow ZSM-5 molecular sieve according to the present invention.

[0263] Performance Testing

[0264] The catalytic cracking catalysts prepared in Examples 8-12, Reference Example 1 and Comparative Examples 7-10 were aged at 800°C and 100% by volume of water vapor for 17 hours, and then their catalytic cracking reaction performance was evaluated in a small fixed fluidized bed reactor. The evaluation conditions were a reaction temperature of 600°C, a catalyst-to-oil ratio of 10 by mass, and a weight hourly space velocity of 10h. -1 , heavy oil properties are shown in Table 5, and reaction results are shown in Table 8.

[0265] Table 8. Catalytic performance evaluation results

[0266] In Table 8, light olefins are the sum of ethylene, propylene, and C4 olefins (olefins with 4 carbon atoms in their molecules). BTX is the sum of benzene, toluene, and xylene.

[0267] As can be seen from Table 8, the catalytic cracking catalyst provided by the present invention has higher light olefins and BTX yields than the comparative catalytic cracking catalyst.

Claims

1. A single crystal hollow ZSM-5 molecular sieve, characterized in that: The particles of the single-crystal hollow ZSM-5 molecular sieve have a single-crystal structure, and the average grain size of the molecular sieve is 0.8-3.5 μm; and have a double-layer cavity structure with inner and outer layers nested, wherein the inner cavity is at least partially enclosed by the first molecular sieve wall layer, and the outer cavity is completely enclosed by the second molecular sieve wall layer, and an epitaxially grown nanorod shell layer is provided on the second molecular sieve wall layer.

2. The single crystal hollow ZSM-5 molecular sieve according to claim 1, characterized in that: The ZSM-5 molecular sieve crystals grow along the ac axis direction, and / or the single crystal hollow ZSM-5 molecular sieve grain length is 0.8-3.5 μm, the grain width is 0.5-2.0 μm, the length of the inner cavity is 0.5-2.0 μm, the width of the inner cavity is 0.3-1.0 μm, the thickness of the first molecular sieve wall is less than 500 nm, and / or the length of the epitaxially grown nanorods is 0.5-1.0 μm.

3. The single crystal hollow ZSM-5 molecular sieve according to any one of claims 1 to 2, characterized in that: After the single crystal hollow ZSM-5 molecular sieve is modified under the condition of a phosphorus / aluminum molar ratio of 1, the obtained single crystal hollow ZSM-5 molecular sieve has a crystal retention greater than or equal to 90% and / or an acid retention greater than or equal to 30% after hydrothermal treatment at 800° C. for 17 hours.

4. The single crystal hollow ZSM-5 molecular sieve according to any one of claims 1 to 2, characterized in that: The mesopore specific surface area of ​​the single crystal hollow ZSM-5 molecular sieve accounts for 15-25% of the total specific surface area, and / or the mesopore volume accounts for 40-60% of the total pore volume.

5. A method for preparing a single crystal hollow ZSM-5 molecular sieve, characterized in that: The particles of the single-crystal hollow ZSM-5 molecular sieve have a single-crystal structure, an average grain size of 0.8-3.5 μm, and a double-layer cavity structure with inner and outer layers nested, wherein the inner cavity is at least partially enclosed by a first molecular sieve wall layer, and the outer cavity is completely enclosed by a second molecular sieve wall layer, and an epitaxially grown nanorod shell layer is provided on the second molecular sieve wall layer, wherein the method comprises step (A) for preparing a seed solution and step (B) for preparing a single-crystal hollow ZSM-5 molecular sieve, wherein: Step (A) comprises the following sub-steps: (A1) mixing a first silicon source, a template and water to obtain a first mixed solution; (A2) subjecting the first mixed solution obtained in sub-step (1) to hydrothermal dynamic crystallization to obtain a seed solution; Step (B) comprises the following sub-steps: (B1) Under stirring, the alkali source solution, the second silicon source dispersion and the aluminum source dispersion are sequentially added. Add to water to obtain a second mixed solution, (B2) adding a certain amount of the seed solution to the second mixed solution under stirring to obtain a third mixed solution; (B3) subjecting the third mixed solution to hydrothermal dynamic crystallization; filtering the obtained product, and optionally washing, drying, and calcining to obtain a parent molecular sieve; (B4) mixing the obtained parent molecular sieve with an alkali solution to obtain a solid product; and optionally (B5) treating the obtained solid product to obtain an H-type single crystal hollow ZSM-5 molecular sieve, and optionally (B6) Introducing phosphorus into the H-type single crystal hollow ZSM-5 molecular sieve obtained in sub-step (5).

6. The method according to claim 5, characterized in that The method comprises step (A) for preparing a seed solution and step (B) for preparing a single crystal hollow ZSM-5 molecular sieve, wherein: Step (A) comprises the following sub-steps: (A1) mixing a first silicon source, a template and water under stirring, preferably stirring and heating at a temperature of 30-60° C. for 2-6 hours to obtain a mixed solution, referred to as a first mixed solution; (A2) subjecting the first mixed solution obtained in sub-step (A1) to hydrothermal dynamic crystallization at a temperature of 140-180° C. for more than 1 hour, for example, 8-24 hours, preferably 10-18 hours, for example, transferring the mixed solution to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and subjecting the mixed solution to hydrothermal crystallization under stirring to obtain a solution containing a crystallized product, referred to as a seed solution; Step (B) comprises the following sub-steps: (B1-1) dissolving an alkali source in water and stirring to obtain an alkali source solution; (B1-2) mixing an aluminum source with water and stirring to obtain an aluminum source dispersion; (B1-3) mixing the second silicon source with the alkali source solution obtained in sub-step (B1-1) under stirring, preferably at room temperature for more than 5 minutes, for example 10-30 minutes; (B1-4) the product obtained in sub-step (B1-3) is optionally mixed with a certain amount of dilution water, and then mixed with the aluminum source dispersion obtained in sub-step (B1-2) under stirring, preferably at room temperature for more than 1 minute, preferably for 30-60 minutes, to obtain a mixed solution, referred to as a second mixed solution; (B2) adding a certain amount of the seed solution obtained in sub-step (A2) to the second mixed solution obtained in sub-step (B1-4) under stirring, preferably stirring at room temperature for more than 10 minutes, for example, stirring for 1-6 hours, to obtain a mixed solution, referred to as a third mixed solution; preferably, the mass of SiO2 in the seed solution is equal to the mass of SiO2 obtained in sub-step (B1-4). The mass ratio of SiO2 in the product is 5-20:100, such as 10:100 or 15:100; (B3) subjecting the third mixed solution obtained in sub-step (B2) to hydrothermal dynamic crystallization at a temperature higher than 100° C., for example, for more than 1 hour, preferably at a temperature of 140-180° C., preferably 150-170° C., for 6-48 hours, preferably 10-40 hours; filtering the obtained product, and optionally washing, drying, and calcining to obtain a parent molecular sieve; (B4) mixing the parent molecular sieve obtained in sub-step (B3) with an alkali-containing solution under stirring, for example, at a temperature of 60-90° C. for, for example, 20-60 minutes, preferably, the alkali content in the alkali-containing solution is 0.4-2.0 mol / L, to obtain a solid product; and optionally (B5) treating the solid product obtained in sub-step (B4) to obtain an H-type single crystal hollow ZSM-5 molecular sieve; and optionally (B6) Introducing phosphorus into the H-type single crystal hollow ZSM-5 molecular sieve obtained in sub-step (B5).

7. The method according to claim 6, characterized in that In sub-step (A1), the first silicon source is one or more of methyl orthosilicate or ethyl orthosilicate, and / or the template is one or more of tetrapropylammonium hydroxide or tetrapropylammonium bromide. Preferably, the molar ratio of the template R / SiO2 is 0.1-0.40, and / or the molar ratio of H2O / SiO2 is 25-65, and / or, in sub-step (A2), the grain size of the seed crystal is 200-800nm.

8. The method according to any one of claims 6 to 7, characterized in that: In sub-step (B1-1), the concentration of the alkali source solution is 10-30 wt %, and the alkali source is selected from one or more of potassium hydroxide, rubidium hydroxide or cesium hydroxide, and / or the concentration of the aluminum source dispersion is 5-20 wt %, and the aluminum source is selected from one or more of aluminum sulfate, aluminum nitrate, aluminum isopropoxide, sodium aluminate or aluminum chloride.

9. The method according to any one of claims 6 to 8, characterized in that: The molar ratio of the second mixed liquid is: n(SiO2) / n(Al2O3)=20-200, for example 30-100, preferably 40-80, more preferably 45-65; n(M12O) / n(SiO2)=0.2-0.5, for example 0.22-0.4, more preferably 0.22-0.35; n(H2O) / n(SiO2)=50-150, for example 60-120, preferably 75-110, wherein M1 represents an alkali metal, preferably one or more selected from K, Rb or Cs.

10. The method according to any one of claims 6 to 9, characterized in that: In sub-step (B1-3), the second silicon source is silica sol, preferably, the silica sol is selected from ammonium silica sol, sodium silica sol or a mixture thereof; the SiO2 content in the silica sol is 15-45% by weight.

11. The method according to any one of claims 6 to 10, characterized in that: In sub-step (B1-3), the stirring time at room temperature is 10-30 minutes, in sub-step (B1-4), the stirring time at room temperature is 30-60 minutes, and / or in sub-step (B3), the stirring time at room temperature is 1-6 hours, and / or in sub-step (B2), the mass ratio of SiO2 in the seed solution to SiO2 in the second silicon source in sub-step (B1-3) is 5-20:100 or 5-10:

100.

12. Use of the single crystal hollow ZSM-5 molecular sieve according to any one of claims 1 to 4 or the single crystal hollow ZSM-5 molecular sieve obtained by the method according to any one of claims 5 to 11, for catalyzing the catalytic cracking reaction of hydrocarbon oil.

13. A catalyst, in particular a catalytic cracking catalyst, characterized in that The catalyst comprises the single crystal hollow ZSM-5 molecular sieve according to any one of claims 1 to 4 or the single crystal hollow ZSM-5 molecular sieve obtained by the method according to any one of claims 5 to 11.

14. The catalyst according to claim 13, characterized in that The catalyst further comprises a Y-type molecular sieve and a carrier. Preferably, based on the dry basis mass of the catalyst, in the catalyst, the content of the single crystal hollow ZSM-5 molecular sieve is 20-50% by weight, the content of the Y-type molecular sieve is 10-30% by weight, and the content of the carrier is 20-70% by weight.

15. The catalyst according to claim 14, characterized in that Based on the dry basis weight of the catalytic cracking catalyst, the catalytic cracking catalyst contains 20-50 wt % of single crystal hollow ZSM-5 molecular sieve, 10-30 wt % of Y-type molecular sieve, 20-50 wt % of clay, 10-30 wt % of acidified pseudo-boehmite, 3-20 wt % of aluminum sol and 2-15 wt % of silica sol.

16. The catalyst according to claim 13, characterized in that The catalyst also comprises a Y-type molecular sieve, a multi-level pore MFI molecular sieve, a nano molecular sieve and a carrier. Preferably, based on the dry weight of the catalyst, in the catalyst, the content of the single crystal hollow ZSM-5 molecular sieve is 10-30% by weight, the content of the Y-type molecular sieve is 5-20% by weight, the content of the multi-level pore MFI molecular sieve is 5-20% by weight, the content of the nano molecular sieve is 3-10% by weight, and the content of the carrier is 20-70% by weight.

17. The catalyst according to claim 16, characterized in that The nano molecular sieve is selected from 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; preferably at least one of Beta, SAPO-5, SAPO-40, SSZ-13, CIT-1, ITQ-7, ZSM-18, mordenite and sodium chabazite.

18. The catalyst according to any one of claims 16-17, wherein The mesopore volume of the multi-level pore MFI molecular sieve accounts for 40-70% of the total pore volume.

19. The catalyst according to any one of claims 13 to 18, characterized in that The single crystal hollow ZSM-5 molecular sieve contains phosphorus or does not contain phosphorus, and its phosphorus content is 0-15% by weight, preferably 0.5-10% by weight, and preferably, the phosphorus / aluminum molar ratio is 0.5-1.

5.

20. The catalyst according to any one of claims 14 to 19, characterized in that The Y-type molecular sieve is a conventional Y-type molecular sieve, for example, one or more selected from rare earth-containing Y-type molecular sieves, hydrothermally ultrastable and / or gas-phase ultrastable Y-type molecular sieves.

21. The catalyst according to any one of claims 14 to 20, characterized in that The carrier is selected from one or more of natural clay, alumina carrier, silica carrier, aluminum phosphate carrier and silica-alumina oxide carrier; preferably, the silica carrier is selected from one or more of neutral silica sol, acidic silica sol or alkaline silica sol; the alumina carrier is selected from one or more of aluminum sol, acidified pseudo-boehmite, hydrated alumina and activated alumina; the aluminum phosphate carrier is selected from phosphate aluminum gel; the silica-alumina oxide carrier is selected from one or more of solid silica-alumina material, silica-alumina sol and silica-alumina gel; preferably, the carrier includes a silica carrier, and the content of the silica carrier in terms of SiO2 is 1-20% by weight based on the dry basis mass of the catalyst.

22. A method for preparing the catalyst according to any one of claims 14-15, characterized in that: The method comprises: spray drying a slurry containing a carrier, a single crystal hollow ZSM-5 molecular sieve, a Y-type molecular sieve and water.

23. A method for preparing a catalyst according to any one of claims 16 to 18, characterized in that: The method comprises: spray drying a slurry containing a carrier, a single crystal hollow ZSM-5 molecular sieve, a Y-type molecular sieve, a multi-level pore MFI molecular sieve, a nano molecular sieve and water.

24. Use of the catalyst according to any one of claims 13 to 15 for catalytic cracking of heavy oil to increase the production of ethylene and BTX.

25. Use of the catalyst according to any one of claims 13 and 16-18 for catalytic cracking of heavy oil to increase the production of light olefins and BTX.

26. A method for catalytic cracking of hydrocarbon oil, comprising contacting the hydrocarbon oil with the single crystal hollow ZSM-5 molecular sieve according to any one of claims 1 to 4 or the catalyst according to any one of claims 13 to 21, preferably, the single crystal hollow molecular sieve is a phosphorus-containing single crystal hollow ZSM-5 molecular sieve and / or an H-type single crystal hollow ZSM-5 molecular sieve.

Images