Catalyst for mass production of propylene and butene, and preparation method therefor and use thereof

Abstract

The present invention belongs to the field of catalytic cracking, and provides a catalyst, more specifically, a catalytic cracking catalyst for mass production of propylene and butene from wax oil distillate and a preparation method therefor. The catalyst comprises 45-80 wt% of a matrix and 20-55 wt% of a molecular sieve, wherein the molecular sieve comprises an MFI type molecular sieve and an optional FAU type molecular sieve, and the MFI type molecular sieve is newly developed particles, and is a ZSM-5 molecular sieve with higher hydrothermal stability, in which secondary particles are formed by the aggregation of primary particles. The catalyst is used for catalytic cracking of wax oil distillate, exhibits good hydrothermal stability and catalytic effect, and can significantly improve the yield of ethylene and propylene.

Description

Catalyst for increasing production of propylene and butene, preparation method thereof, and application thereof Technical Field

[0001] The present invention relates to a catalytic cracking catalyst, a preparation method and application thereof, and more particularly to a catalytic cracking catalyst for producing more propylene and butene using wax oil fraction as a raw material, a preparation method and application thereof. Background Art

[0002] Propylene and butene are important petrochemical products, with demand increasing in recent years. Their primary production pathways include catalytic cracking, steam cracking, and catalytic cracking. Catalytic cracking, under the action of a catalyst, operates at lower temperatures than steam cracking, and offers flexible and adjustable product distribution. Therefore, significantly increasing propylene and butene production through catalytic cracking is a highly effective way to meet growing demand.

[0003] ZSM-5 is a key active component in existing catalytic cracking catalysts. Industrial ZSM-5 zeolites are primarily sized between 2 and 5 microns, primarily containing micropores. However, due to diffusion limitations within the micropores of conventional ZSM-5 zeolites, conversion of large molecules is poor. The zeolite's grain size affects the diffusion of reactant and product molecules, which in turn affects the reconversion of target products such as light olefins. To improve diffusivity, researchers have developed nanoscale zeolites, which enhance diffusion and reaction by optimizing pore length and width. These zeolites typically range in size from 50 nm to 1 micron. For the same mass, nanoscale zeolites have more pores and shorter pores, allowing reactant molecules more opportunities to enter the pores for reaction while allowing product molecules to diffuse more freely out of the pores, preventing reconversion reactions. This improves the selectivity of target products such as light olefins and reduces the selectivity of coke.

[0004] Chinese invention patent CN1730391A reports a method for synthesizing nano-ZSM-5 molecular sieves using a template and microwave method. The method involves uniformly mixing the template agent tetrapropylammonium hydroxide, a silicon source, and an aluminum source. The mixture is then microwaved for 3 to 180 minutes, or microwaved for 3 to 30 minutes followed by crystallization at 150 to 190°C for 1 to 3 days to produce ZSM-5 molecular sieves with a grain size of 50 to 300 nm.

[0005] The paper "Low temperature synthesis and properties of ZSM-5 aggregates formed by ultra-small nanocrystals" describes a method for synthesizing nano-ZSM-5 using low-temperature crystallization and a template. This method uses TPAOH, TEOS, and isopropyl aluminum as raw materials. Crystallization is performed at 70-90°C for more than 12 days to produce ZSM-5 aggregates composed of 10-20 nm ZSM-5 molecular sieves with a silicon-to-aluminum ratio of less than 60 and a TPAOH / Si ratio of approximately 0.36. However, this method produces a relatively low molecular sieve yield.

[0006] Chinese invention patent CN101837298B discloses a method for synthesizing ZSM-5 molecular sieves with a particle size of 60 to 100 nm using a ternary organic template, wherein the ternary organic template comprises an alkyl alcohol, an alkylamine, and an aromatic amine.

[0007] However, the existing small-grain ZSM-5 molecular sieve has the problem of low stability.

[0008] Existing catalytic cracking catalysts often contain other molecular sieves and matrices to enable gradient reactions and adjust reaction products, thereby causing the hydrocarbon feedstock to undergo stepwise cracking in the catalyst. However, the existing technology does not provide a method for further improving the propylene and butene yields of catalytic cracking catalysts.

[0009] Wax oil distillate is one of the commonly used feedstocks for producing light olefins. However, the catalytic cracking capacity and light olefin yield of catalytic cracking catalysts prepared using existing ZSM-5 molecular sieves still need to be improved. The existing technology does not provide a method for developing high-performance catalytic cracking catalysts for wax oil distillate to fully utilize wax oil distillate resources and further increase the yields of propylene and butene.

[0010] It should be noted that the information disclosed in the aforementioned background technology section is only used to enhance the background understanding of the present invention, and therefore it may include information that does not constitute the prior art known to ordinary technicians in this field. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a catalytic cracking catalyst and a preparation method and application of the catalyst, in particular a catalyst for catalytic cracking of wax oil fractions to produce more propylene and butene and a preparation method and application of the catalyst.

[0012] After extensive research, the inventors have discovered that the yields of propylene and butene in the catalytic cracking products can be increased by using a catalyst comprising a ZSM-5 molecular sieve having specific physical properties as an MFI molecular sieve and, optionally, a FAU molecular sieve. The present invention further provides a method for preparing and using the catalyst.

[0013] More specifically, the present invention provides a catalyst, characterized in that, based on the total weight of the catalyst, the catalyst comprises 45 to 80 wt% of a matrix and 20 to 55 wt% of a molecular sieve, wherein the molecular sieve comprises an MFI type molecular sieve and optionally a FAU type molecular sieve.

[0014] The MFI type molecular sieve is a ZSM-5 molecular sieve, and the ZSM-5 molecular sieve is a secondary particle formed by the aggregation of primary particles;

[0015] The proportion of aluminum forming Al-pair in the ZSM-5 molecular sieve to the total framework aluminum is no more than 20%, preferably no more than 18%.

[0016] In the catalyst of the present invention, the FAU type molecular sieve is optional. When the FAU type molecular sieve is present, the weight ratio of the FAU type molecular sieve to the MFI type molecular sieve is 0.18 to 1.5:1, for example, 0.25 to 1.1:1, more preferably 0.3 to 1:1.

[0017] In the catalyst of the present invention, based on the total dry weight of the catalyst, the matrix content is 50-78 weight %, the FAU structure molecular sieve content is 0-20 weight %, and the MFI structure molecular sieve content is 10-30 weight %.

[0018] In the catalyst of the present invention, based on the total dry weight of the catalyst, the matrix content is 55-75 weight %, the FAU molecular sieve content is 5-16 weight %, and the ZSM-5 molecular sieve content is 12-30 weight %.

[0019] The present invention further provides a method for preparing the catalyst, wherein the matrix, molecular sieve and water are slurried to form a slurry, which is then spray-dried.

[0020] The present invention also provides use of the catalyst of the present invention in catalytic cracking of wax oil fractions.

[0021] Technical Effects

[0022] The present invention provides a catalyst cracking catalyst having excellent hydrothermal stability. Furthermore, when the ZSM-5 molecular sieve of the present invention is used for catalytic conversion of wax oil fractions, higher propylene yield and butene yield are exhibited.

[0023] The catalyst cracking catalyst provided by the invention is suitable for converting wax oil fractions to increase the production of propylene and butene. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is an XRD pattern of the ZSM-5 molecular sieve obtained in Example 1.

[0025] Figure 2 is a SEM scanning electron microscope photograph of the ZSM-5 molecular sieve obtained in Example 2.

[0026] FIG3 is an XRD pattern of the ZSM-5 molecular sieve obtained in Example 4.

[0027] FIG4 is a SEM scanning electron microscope photograph of the ZSM-5 molecular sieve obtained in Comparative Example 1.

[0028] Figure 5 is the XRD pattern of the ZSM-5 molecular sieve obtained in Comparative Example 3. DETAILED DESCRIPTION

[0029] The structure, principle and preparation process of the catalyst of the present invention are further described in detail below.

[0030] In the present invention, except for the contents explicitly described, any matters or issues not mentioned are directly applicable to the contents 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 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.

[0031] All features disclosed in the present invention may be combined in any combination, and such combinations should be understood as disclosed or described in the present invention. Unless a person skilled in the art considers such combination to be obviously unreasonable, such combinations should be considered as specifically disclosed and described in the present invention. Unless otherwise specified, the numerical values ​​disclosed in this specification include not only the numerical values ​​specifically disclosed in the examples but also the endpoints of the numerical ranges in the specification. Any combination of these numerical values ​​should be considered as the range disclosed or described in the present invention.

[0032] Technical and scientific terms in the present invention shall be understood according to their definitions if they are defined, and shall be understood according to their general meanings in the art if they are not defined.

[0033] In the context of the present invention, unless otherwise specified, the physical properties of a substance (such as boiling point) are all measured values ​​at normal temperature (25° C.) and normal pressure (101325 Pa).

[0034] In the present invention, the wax oil distillate can be, for example, a distillate obtained by distillation of paraffinic crude oil, such as vacuum wax oil or atmospheric wax oil. In one embodiment of the present invention, the saturated hydrocarbon content in the wax oil distillate is not less than 50% by weight, for example, 50 to 85% by weight.

[0035] The first aspect of the present invention provides a catalyst, characterized in that, based on the total weight of the catalyst, the catalyst comprises 45 to 80 wt% of a matrix and 20 to 55 wt% of a molecular sieve, wherein the molecular sieve comprises an MFI type molecular sieve and an optional FAU type molecular sieve.

[0036] The MFI type molecular sieve is a ZSM-5 molecular sieve, and the ZSM-5 molecular sieve is a secondary particle formed by the aggregation of primary particles;

[0037] The proportion of aluminum forming Al-pair in the ZSM-5 molecular sieve to the total framework aluminum is no more than 20%, preferably no more than 18%.

[0038] In the present invention, the Al-pair (Al pair or aluminum pair) in the molecular sieve refers to: in ZSM-5, Al-O-(Si-O) n In an -Al structure, when the number of silicon atoms between two aluminum atoms is 1 to 3 (i.e., n is 1 to 3), the structure is called an Al-pair. For details, see the description in Engineering of Transition Metal Catalysts Confined in Zeolites (Chem. Mater. 2018, 30, 10, 3177-3198).

[0039] In one embodiment of the present invention, the ratio of aluminum forming Al-pair in the ZSM-5 molecular sieve to the total framework aluminum is 0, that is, the molecular sieve does not contain aluminum forming Al-pair.

[0040] In the present invention, the primary particles of ZSM-5 molecular sieve refer to the crystallites of ZSM-5 molecular sieve.

[0041] In the present invention, the secondary particles of the ZSM-5 molecular sieve refer to particles formed by the growth of primary particles in a dense and / or loose manner.

[0042] In the present invention, the average crystal grain size of primary particles and the average particle size of secondary particles are measured according to the methods described in Examples.

[0043] In the present invention, the relative crystallinity of ZSM-5 molecular sieve is measured by XRD. Powder X-ray diffraction (XRD) is measured on an X-ray diffractometer with Cu-Kα radiation (λ = 1.5406á) with a 2θ range of 5° to 50° and a scanning speed of 2° min -1 . See NB / SH / T6024-2021.

[0044] In the present invention, the ZSM-5 molecular sieve is a nano-sized ZSM-5 molecular sieve with high hydrothermal stability.

[0045] In one embodiment of the present invention, the ZSM-5 molecular sieve is a ZSM-5 molecular sieve having the following properties: phosphorus is introduced into the ZSM-5 molecular sieve to obtain a molecular sieve with a P / Al molar ratio of 1, and the molecular sieve with a P / Al molar ratio (sometimes referred to as the phosphorus-aluminum ratio in the present invention) of 1 is aged for 30 hours at 800°C and 100% by volume of water vapor. The crystal retention rate is not less than 90% relative to the molecular sieve with a P / Al molar ratio of 1 before aging, and the crystal retention rate is preferably 90-99% or 91-98%.

[0046] In one embodiment of the present invention, the ZSM-5 molecular sieve is a ZSM-5 molecular sieve having the following properties: phosphorus is introduced into the ZSM-5 molecular sieve to obtain a molecular sieve with a P / Al molar ratio of 1, and the molecular sieve with a P / Al molar ratio of 1 is aged for 30 hours at 800°C and 100% by volume of water vapor. The acid retention rate measured by NH3-TPD is not less than 30% relative to the molecular sieve with a P / Al molar ratio of 1 before aging, and the acid retention rate is preferably 32-48% or 35-42%.

[0047] In one embodiment of the present invention, the method of introducing phosphorus as described above can be carried out as follows: phosphorus is impregnated into the ZSM-5 molecular sieve according to a P / Al ratio of 1 (molar ratio), optionally dried, and optionally calcined to obtain a phosphorus-containing ZSM-5 molecular sieve; for the phosphorus impregnation method, an aqueous solution containing one or more of orthophosphoric acid, phosphorous acid, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, aluminum phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, pyrophosphoric acid or ammonium phosphate can be used, and the impregnation is carried out by an equal volume impregnation or excess impregnation method, and the P / Al molar ratio in the molecular sieve is made to be 1 by the impregnation. For example, in one embodiment of the present invention, the preparation method of the phosphorus-containing ZSM-5 molecular sieve is to introduce phosphorus by impregnation in an equal volume manner according to a P / Al molar ratio of 1, drying, and calcining at 550°C for 3h.

[0048] In one embodiment of the present invention, the ZSM-5 molecular sieve may or may not contain phosphorus. The phosphorus content of the ZSM-5 molecular sieve, calculated as P2O5, is 0 to 15 wt%, for example, 0 to 10 wt%. In the present invention, unless otherwise specified, ZSM-5 molecular sieves, regardless of whether they contain phosphorus, may be collectively referred to as ZSM-5 molecular sieves.

[0049] In the present invention, the ZSM-5 molecular sieve containing phosphorus is also referred to as a phosphorus-containing ZSM-5 molecular sieve, and the ZSM-5 molecular sieve not containing phosphorus is also referred to as a phosphorus-free ZSM-5 molecular sieve. In one embodiment of the present invention, the phosphorus content of the phosphorus-containing ZSM-5 molecular sieve is 0.5 to 15 wt%, for example, 1 to 10 wt% or 1 to 8 wt%, calculated as P2O5.

[0050] In one embodiment of the present invention, when the ZSM-5 molecular sieve contains phosphorus and the P / Al molar ratio is greater than 1, the phosphorus-containing ZSM-5 molecular sieve is aged at 800°C and 100% by volume of water vapor for 30 hours. The crystal retention rate is not less than 90%, for example, 90-99% or 91-98%, relative to the phosphorus-containing ZSM-5 molecular sieve before aging.

[0051] In one embodiment of the present invention, when the ZSM-5 molecular sieve contains phosphorus and the P / Al molar ratio is above 1, the phosphorus-containing ZSM-5 molecular sieve is aged at 800°C and 100% by volume of water vapor for 30 hours. The acid retention rate measured by NH3-TPD is not less than 30%, for example, 32-48% or 35-42%, relative to the phosphorus-containing ZSM-5 molecular sieve before aging.

[0052] In one embodiment of the present invention, the phosphorus-free ZSM-5 molecular sieve and the phosphorus-containing ZSM-5 molecular sieve with a P / Al molar ratio of less than 1 have the following properties: when phosphorus is introduced into the phosphorus-free ZSM-5 molecular sieve or the phosphorus-containing ZSM-5 molecular sieve with a P / Al molar ratio of less than 1 to obtain a molecular sieve with a P / Al molar ratio of 1, the molecular sieve with a P / Al molar ratio of 1 is aged for 30 hours at 800°C and 100% by volume of water vapor, and the crystallization retention rate is not less than 90%, for example, 90-99% or 91-98%, relative to the molecular sieve with a P / Al molar ratio of 1 before aging.

[0053] In one embodiment of the present invention, the phosphorus-free ZSM-5 molecular sieve and the phosphorus-containing ZSM-5 molecular sieve with a P / Al molar ratio of less than 1 have the following properties: when phosphorus is introduced into the phosphorus-free ZSM-5 molecular sieve or the phosphorus-containing ZSM-5 molecular sieve with a P / Al molar ratio of less than 1 to obtain a molecular sieve with a P / Al molar ratio of 1, the molecular sieve with a P / Al molar ratio of 1 is aged for 30 hours at 800°C and 100% by volume of water vapor, and the acid retention measured by NH3-TPD is not less than 30%, for example, 32 to 48% or 35 to 42% relative to the molecular sieve with a P / Al molar ratio of 1 before aging.

[0054] In the present invention, whether it is a phosphorus-free ZSM-5 molecular sieve, a phosphorus-containing ZSM-5 molecular sieve with a P / Al molar ratio of 1 or more, or a phosphorus-containing ZSM-5 molecular sieve with a P / Al molar ratio of less than 1, they are all ZSM-5 molecular sieves of the present invention.

[0055] The crystallinity retention of the ZSM-5 molecular sieve in the present invention is represented by: 1) when the molecular sieve is a phosphorus-free ZSM-5 molecular sieve and a phosphorus-containing ZSM-5 molecular sieve with a P / Al molar ratio of less than 1, phosphorus is introduced into the phosphorus-free ZSM-5 molecular sieve or the phosphorus-containing ZSM-5 molecular sieve with a P / Al molar ratio of less than 1 to obtain a molecular sieve with a P / Al molar ratio of 1, and the molecular sieve with a P / Al molar ratio of 1 is aged at 800° C. and 100% by volume of water vapor for 30 hours, and the crystallinity retention is calculated relative to the molecular sieve with a P / Al molar ratio of 1 before aging (see the examples for the calculation formula); 2) when the molecular sieve is a phosphorus-containing ZSM-5 molecular sieve and the P / Al molar ratio is greater than 1, the crystallinity retention is calculated relative to the phosphorus-containing ZSM-5 molecular sieve before aging after aging at 800° C. and 100% by volume of water vapor for 30 hours (see the examples for the calculation formula).

[0056] The acid retention of the ZSM-5 molecular sieve in the present invention is represented by: 1) when the molecular sieve is a phosphorus-free ZSM-5 molecular sieve and a phosphorus-containing ZSM-5 molecular sieve with a P / Al molar ratio of less than 1, phosphorus is introduced into the phosphorus-free ZSM-5 molecular sieve or the phosphorus-containing ZSM-5 molecular sieve with a P / Al molar ratio of less than 1 to obtain a molecular sieve with a P / Al molar ratio of 1, and the molecular sieve with a P / Al molar ratio of 1 is aged at 800°C and 100% by volume of water vapor for 30 hours, relative to the acid retention before aging The molecular sieve having a P / Al molar ratio of 1 and an acid retention rate measured by NH3-TPD (see the example for the calculation formula); 2) when the molecular sieve is a phosphorus-containing ZSM-5 molecular sieve and the P / Al molar ratio is above 1, the phosphorus-containing ZSM-5 molecular sieve is aged at 800°C and 100% by volume of water vapor for 30 hours, relative to the molecular sieve having a P / Al molar ratio of 1 or above before aging, the acid retention rate measured by NH3-TPD (see the example for the calculation formula).

[0057] The results of the above aging tests, in particular, the crystal retention and acid retention of the molecular sieve of the present invention are within specific ranges, indicating that the ZSM-5 molecular sieve of the present invention has excellent hydrothermal stability.

[0058] When preparing the catalyst of the present invention, ZSM-5 molecular sieves that do not contain phosphorus or ZSM-5 molecular sieves that contain phosphorus can be directly used.

[0059] In other words, in the present invention, the technical problem of the present invention can be solved when the phosphorus content in the ZSM-5 molecular sieve is 0-15% in terms of P2O5.

[0060] In one embodiment of the present invention, the ZSM-5 molecular sieve is preferably a phosphorus-containing ZSM-5 molecular sieve. In this case, the phosphorus content in the phosphorus-containing ZSM-5 molecular sieve is 0.5 to 15 weight %, for example, 1 to 10 weight % or 1 to 8 weight %, calculated as P2O5.

[0061] In one embodiment of the present invention, the ZSM-5 molecular sieve is a phosphorus-containing ZSM-5 molecular sieve, and the f value of the phosphorus distribution in the ZSM-5 molecular sieve satisfies: 55%≤f≤85%, and f=P2 / P1×100%, wherein P1 represents the phosphorus mass content of any crystal surface of the molecular sieve grains measured by the XPS method, and P2 represents the phosphorus mass content of any crystal surface of the molecular sieve grains after ion sputtering for 100s measured by the XPS method.

[0062] The XPS measurement method is: X-ray photoelectron spectroscopy (XPS, Thermo Scientific ESCALAB Xi +Equipped with a monochromatic 150W Al Kα radiation source combined with argon ion etching, the chemical state and distribution of elements on and within the ZSM-5 molecular sieve were analyzed. Binding energies were calibrated using the C1s peak of exogenous carbon at 284.8eV.

[0063] In the present invention, the phosphorus-containing ZSM-5 molecular sieve is treated by ion sputtering method, which is to use argon ions on Ta2O5 at a sputtering rate of 0.3nm / s for 100s, thereby performing argon ion sputtering stripping on the sample surface.

[0064] In the present invention, by making the f value of phosphorus distribution in the phosphorus-containing ZSM-5 molecular sieve satisfy the following conditions: 55%≤f≤85%, phosphorus can be distributed in the ZSM-5 grains in a special distribution state.

[0065] In one embodiment of the present invention, the sodium oxide content in the ZSM-5 molecular sieve is preferably no more than 0.15 wt % based on the dry weight of the ZSM-5 molecular sieve.

[0066] In one embodiment of the present invention, the ZSM-5 molecular sieve is a secondary particle formed by aggregation of primary particles, and the average particle size of the secondary particles is 100 to 900 nm, preferably 200 to 700 nm.

[0067] In one embodiment of the present invention, the variance of the average particle size of the secondary particles of the ZSM-5 molecular sieve does not exceed 0.03 μm. 2 , for example, 0.001 to 0.03 μm 2 or not more than 0.015μm 2 or not more than 0.01μm 2 Or 0.001~0.0012μm 2 The ZSM-5 molecular sieve has a small variance in the size of secondary particles, good uniformity in particle distribution, and good hydrothermal stability.

[0068] In one embodiment of the present invention, the primary particles of the ZSM-5 molecular sieve are ZSM-5 molecular sieve grains, and the average grain size of the primary particles does not exceed 100 nm. For example, the average grain size of the primary particles is 10 to 100 nm, for example, 30 to 99 nm, 35 to 95 nm, or 50 to 95 nm.

[0069] In one embodiment of the present invention, the relative crystallinity of the ZSM-5 molecular sieve may be 50% to 80%, for example, 50% to 70% or 65% to 80% or 70% to 75%.

[0070] In one embodiment of the present invention, the silicon-aluminum ratio of the ZSM-5 molecular sieve can be 20-60, for example, 20-50 or 20-40, calculated as SiO2 / Al2O3 molar ratio.

[0071] In one embodiment of the present invention, the ZSM-5 molecular sieve has a rich intercrystalline mesoporous structure. Wherein, the mesopore volume of the ZSM-5 molecular sieve exceeds 35%, for example, the mesopore volume accounts for not less than 35% and not more than 86%, for example, 40% to 70% or 42% to 65%. In the present invention, the mesopore volume ratio refers to the ratio of the mesopore volume to the total pore volume. The mesopore volume and the total pore volume are determined by the nitrogen adsorption capacity method, the specific surface area is calculated according to the BET equation, and the pore size distribution is calculated by the BJH method. For the measurement method, see NB / SH / T0959-2017.

[0072] In one embodiment of the present invention, the ZSM-5 molecular sieve can be manufactured by a preparation method comprising the following steps:

[0073] (1) mixing an alkali, a silicon source, water, a seed crystal, and an optional aluminum source to form a crystallization solution; the amount of the seed crystal containing a weak acid does not exceed 35 ml / g;

[0074] (2) performing step-by-step crystallization of the crystallization solution; wherein the first step crystallization temperature is 5° C. to 90° C., the first step crystallization time is 0.5 h or more, for example, 0.5 to 48 h, the second step crystallization temperature is greater than 120° C., and the second step crystallization time is 3 to 72 h;

[0075] (3) Recovering ZSM-5 molecular sieve.

[0076] According to the catalyst of the present invention, wherein, in step (1) of the preparation method of the ZSM-5 molecular sieve, alkali, silicon source, water, seed crystal and optional aluminum source are mixed to form a crystallization solution. In one embodiment of the present invention, the seed crystal contains ZSM-5 molecular sieve, wherein the content of ZSM-5 molecular sieve in the seed crystal containing ZSM-5 molecular sieve is preferably not less than 8 weight %, such as 8 to 99 weight %, such as 35 to 70 weight %. In one embodiment of the present invention, the seed crystal is ZSM-5 molecular sieve.

[0077] In one embodiment of the present invention, in the seed crystals, the volume of particles having a particle size of no more than 80 microns accounts for more than 95% of the total particle volume. In the present invention, the particle size of the seed crystals is measured by laser particle size analysis, as described in standard NB / SH / T 0951-2017.

[0078] In one embodiment of the present invention, according to the catalyst of the present invention, in the preparation method of the ZSM-5 molecular sieve, the specific surface area of ​​the seed crystal is not less than 180m 2 / g is, for example, 180 to 500 m2 / g,

[0079] In one embodiment of the present invention, according to the catalyst of the present invention, in the preparation method of the ZSM-5 molecular sieve, the weak acid amount of the seed crystal does not exceed 35 ml / g, for example, 0-30 ml / g or 0-25 ml / g or 0-20 ml / g or 0.1-30 ml / g or 0.5-20 ml / g. In the present invention, the weak acid amount of the seed crystal is the acid amount at 120-300°C measured by the NH3-TPD method, and the acid amount is the volume of ammonia desorbed at 120-300°C converted to standard conditions.

[0080] In one embodiment of the present invention, according to the catalyst of the present invention, in the preparation method of the ZSM-5 molecular sieve, in step (1), the amount of the alkali, silicon source and aluminum source is adjusted so that the molar ratio of the mineralizer metal oxide, silicon source SiO2, aluminum source Al2O3 and H2O in the crystallization solution is (0.01~0.15):1:(0~0.055):(5~100), preferably (0.05~0.15):1:(0.005~0.04):(10~50). In the present invention, the amount of silicon source SiO2 is obtained by converting the amount of silicon element in the silicon source into the amount of SiO2, the amount of aluminum source Al2O3 is obtained by converting the amount of aluminum element in the aluminum source into the amount of Al2O3, and the amount of mineralizer metal oxide is the total amount of the amount of mineralizer metal element in the alkali, aluminum source, and silicon source converted into the amount of mineralizer metal oxide. The mineralizer metal is an alkali metal (represented by M) and / or an alkaline earth metal (represented by M'), preferably an alkali metal. The oxide of the alkali metal is calculated as M2O, and the oxide of the alkaline earth metal is calculated as M'O. Therefore, the amount of the mineralizer metal oxide refers to the total amount of (M2O + M'O).

[0081] In one embodiment of the present invention, according to the catalyst of the present invention, in the preparation method of the ZSM-5 molecular sieve, in step (1), the amount of the seed crystal added does not exceed 30% by weight of the amount of the silicon source SiO2, for example, 0.5 to 30% by weight or 5 to 20% by weight, and the amount of the silicon source SiO2 is the amount of silicon element in the silicon source converted into SiO2.

[0082] In one embodiment of the present invention, in step (1) of the preparation method of the ZSM-5 molecular sieve, the mineralizer metal is an alkali metal, the alkali metal is represented by M, and the ratio of the alkali metal to the silicon source SiO2 is 0.05 to 0.15:1 in terms of the molar ratio of M2O:SiO2, preferably 0.1 to 0.15:1.

[0083] In one embodiment of the present invention, the ratio of the aluminum source Al2O3 to the silicon source SiO2 is 0 to 0.055:1, preferably 0.005 to 0.045:1, in terms of the molar ratio of Al2O3:SiO2.

[0084] In one embodiment of the present invention, the ratio of water to the silicon source SiO2 is 10 to 100:1, preferably 10 to 50:1, and more preferably 10 to 30:1, in terms of H2O:SiO2 molar ratio.

[0085] In one embodiment of the present invention, the ratio of the seed crystal to the silicon source SiO2 is 0.05 to 0.3:1, preferably 0.1 to 0.25:1, in terms of the seed crystal / SiO2 weight ratio. The silicon source SiO2 amount is the amount of silicon element in the silicon source converted into SiO2.

[0086] In one embodiment of the present invention, the pH value of the crystallization solution obtained in step (1) is 11.0 to 13.5.

[0087] In one embodiment of the present invention, in step (1) of the preparation method of the ZSM-5 molecular sieve, the aluminum source can be one or more of aluminum hydroxide, pseudo-boehmite, sodium aluminate, aluminum isopropoxide, aluminum sulfate, aluminum acetate, elemental aluminum, aluminum nitrate, aluminum sol, aluminum oxide and aluminum chloride.

[0088] In one embodiment of the present invention, in step (1) of the method for preparing the ZSM-5 molecular sieve, the silicon source may be one or more of silica sol, white carbon black, tetramethyl orthosilicate, tetraethyl orthosilicate, sodium silicate, water glass, solid silica gel and sodium fluorosilicate.

[0089] In one embodiment of the present invention, in step (1) of the method for preparing the ZSM-5 molecular sieve, the base may be an alkali metal and / or alkaline earth metal and / or a basic compound of nitrogen, for example, one or more of sodium carbonate, sodium hydroxide, sodium bicarbonate, potassium carbonate, potassium bicarbonate, potassium hydroxide, aqueous ammonia, and calcium hydroxide.

[0090] In one embodiment of the present invention, the base includes a first base and / or a second base, for example, a first base and an optional second base, wherein the first base is a mineralizer base, for example, one or more of sodium carbonate, sodium hydroxide, sodium bicarbonate, potassium carbonate, potassium bicarbonate or potassium hydroxide, and calcium hydroxide, and the second base is a pH adjustment base, for example, aqueous ammonia, and the pH of the crystallization solution can be adjusted to preferably 11.0 to 13.5 by adding the second base.

[0091] In one embodiment of the present invention, in step (1) of the method for preparing ZSM-5 molecular sieve, the water may be one or more of cation exchange water, anion exchange water, deionized water, and distilled water.

[0092] In one embodiment of the present invention, in step (2) of the preparation method of the ZSM-5 molecular sieve, the crystallization liquid is crystallized in steps; the crystallization temperature of the first step crystallization is 5°C to 90°C, and the crystallization time is 0.5 to 48 hours; the crystallization temperature of the second step crystallization exceeds 120°C, and the crystallization time of the second step is 3 to 72 hours.

[0093] In one embodiment of the present invention, in step (2) of the method for preparing ZSM-5 molecular sieve, the crystallization temperature of the first crystallization step is 25°C to 90°C, for example, 25°C to 80°C or 25°C to 70°C.

[0094] In one embodiment of the present invention, in step (2) of the method for preparing the ZSM-5 molecular sieve, the crystallization time of the first crystallization step is 0.5 to 24 hours, such as 0.5 to 20 hours or 8 to 20 hours.

[0095] In one embodiment of the present invention, in step (2) of the method for preparing ZSM-5 molecular sieve, the crystallization temperature of the second step crystallization is greater than 120°C and less than 200°C, preferably 150°C to 180°C.

[0096] In one embodiment of the present invention, in step (2) of the method for preparing the ZSM-5 molecular sieve, the crystallization time of the second step is 3 to 72 hours, preferably 10 to 60 hours.

[0097] In one embodiment of the present invention, in step (2) of the preparation method of the ZSM-5 molecular sieve, the crystallization temperature of the second step crystallization is 150°C to 180°C, for example, 160°C to 175°C, and the crystallization time of the second step crystallization is 10 to 60 hours, for example, 20 to 60 hours or 20 to 48 hours.

[0098] In one embodiment of the present invention, in step (2) of the method for preparing ZSM-5 molecular sieve, after the first crystallization step, the temperature is raised to the crystallization temperature of the second crystallization step, and the heating rate is preferably 2-10°C / min.

[0099] In one embodiment of the present invention, in step (2) of the method for preparing the ZSM-5 molecular sieve, the first crystallization step can be performed under stirring or under static crystallization, and the stirring speed of the crystallization under stirring can be 1 to 1000 rpm.

[0100] In one embodiment of the present invention, in step (2) of the method for preparing ZSM-5 molecular sieve, the second crystallization step is preferably carried out under stirring at a stirring speed of 1 to 1000 rpm; a crystallized product liquid is obtained after the second crystallization step.

[0101] In one embodiment of the present invention, in the method for preparing the ZSM-5 molecular sieve, step (3) of recovering the molecular sieve can be performed according to conventional recovery methods for preparing molecular sieves in the art.

[0102] In one embodiment of the present invention, the recovery in step (3) comprises separation, optional washing, optional exchange of alkali metals, optional drying and optional roasting.

[0103] In one embodiment of the present invention, in step (3) of the method for preparing the ZSM-5 molecular sieve, in the operation of recovering the molecular sieve, the separation can be carried out by filtration or centrifugation, and conventional filtration or centrifugation methods well known to those skilled in the art can be used. The ZSM-5 molecular sieve obtained by separation is an alkali metal-containing ZSM-5 molecular sieve.

[0104] In one embodiment of the present invention, in step (3) of the method for preparing the ZSM-5 molecular sieve, during the molecular sieve recovery operation, the separated ZSM-5 molecular sieve may be further washed to remove impurities such as unreacted raw materials. The washing method may refer to the washing method of the prior art, for example, water washing may be used, followed by filtration or centrifugation.

[0105] In one embodiment of the present invention, in step (3) of the preparation method of the ZSM-5 molecular sieve, in the molecular sieve recovery operation, the exchange of alkali metal is to reduce the alkali metal content, such as sodium content, in the molecular sieve by exchange, which can be carried out in a manner known in the art. Specifically, the washed ZSM-5 molecular sieve is subjected to ion exchange, and the exchange method is well known to those skilled in the art, such as contacting the separated and / or washed ZSM-5 molecular sieve with an ammonium salt and / or an acid aqueous solution to exchange the alkali metal oxide, such as sodium oxide, in the obtained ZSM-5 molecular sieve to no more than 0.15% by weight, such as 0.01 to 0.15% by weight. In one embodiment of the present invention, the exchange is carried out at 50 to 90° C. with an aqueous solution of ammonium salt according to a weight ratio of ammonium salt aqueous solution: molecular sieve = 5 to 15: 1, and the concentration of ammonium salt in the aqueous solution of ammonium salt can be 1 to 10% by weight.

[0106] In one embodiment of the present invention, in step (3) of the method for preparing ZSM-5 molecular sieve, in the molecular sieve recovery operation, the calcination can be conventional, for example, calcination can be performed at a temperature of 400-600°C for 1-5 hours.

[0107] In one embodiment of the present invention, the preparation method of the ZSM-5 molecular sieve may further include step (4), wherein the ZSM-5 molecular sieve obtained in step (3) is further subjected to phosphorus modification to obtain a phosphorus-containing ZSM-5 molecular sieve. In one embodiment of the present invention, phosphorus modification can be performed by methods known in the art, such as introducing phosphorus into the ZSM-5 molecular sieve by an impregnation method. For example, phosphorus is introduced by an isometric impregnation method. For example, the dried and / or calcined molecular sieve is contacted with a solution of a phosphorus-containing compound for impregnation.

[0108] In one embodiment of the present invention, step (4) of the method for preparing the ZSM-5 molecular sieve can be performed as follows:

[0109] 1) For the ZSM-5 molecular sieve obtained in step (3), use ammonium salt to perform hydrothermal exchange, and then dry and roast. Preferably, the ZSM-5 molecular sieve, ammonium salt and water are exchanged at a weight ratio of 1:0.2 to 1.0:5 to 20 at 60 to 95 ° C for 0.5 to 2 hours, and then dried and roasted. The ammonium salt is at least one selected from ammonium chloride, ammonium nitrate, ammonium carbonate, ammonium bicarbonate, ammonium oxalate, ammonium sulfate, and ammonium bisulfate.

[0110] 2) contacting the ammonium exchange product in step 1) with a phosphorus-containing compound, and then drying and calcining. Preferably, the ammonium exchange product in step 1) is immersed in an aqueous solution of a phosphorus-containing compound, and then drying and calcining. The phosphorus-containing compound is at least one selected from orthophosphoric acid, phosphorous acid, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, aluminum phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, and pyrophosphoric acid.

[0111] In one embodiment of the present invention, the molecular sieve obtained in step (4) is a phosphorus-containing ZSM-5 molecular sieve, and the phosphorus content in the phosphorus-containing ZSM-5 molecular sieve can be 0.5% to 15% by weight as calculated as P2O5. Preferably, the phosphorus content in the phosphorus-containing ZSM-5 molecular sieve is 1% to 15% by weight, for example, 1% to 10% by weight as calculated as P2O5.

[0112] In one embodiment of the present invention, the ZSM-5 molecular sieve is obtained by a preparation method comprising the following steps:

[0113] (1) dissolving a first base and an aluminum source in water, then adding a silicon source, mixing uniformly, and adding seed crystals to obtain a crystallization solution, wherein the amount of weak acid in the seed crystals does not exceed 35 ml / g, and optionally using a second base to adjust the pH of the crystallization solution;

[0114] (2) performing a first crystallization step at a temperature of 5° C. to 90° C., for example, 25° C. to 80° C., for 0.5 to 48 hours, with a stirring speed of, for example, 0 to 1000 rpm (i.e., stirring may be performed without stirring or at a speed greater than 0 to 1000 rpm); then performing a second crystallization step at a temperature greater than 120° C. and less than 200° C., for example, 150 to 180° C., for 3 to 72 hours;

[0115] (3) After the crystallization is completed, the ZSM-5 molecular sieve is obtained by filtering or centrifuging, washing, exchanging with an aqueous solution of ammonium salt, drying and calcining;

[0116] Optionally, (4) the ZSM-5 molecular sieve obtained in step (3) is subjected to phosphorus modification to obtain a phosphorus-containing ZSM-5 molecular sieve. By this embodiment, the obtained ZSM-5 molecular sieve particles have a more uniform particle size distribution and better hydrothermal stability.

[0117] The catalyst provided by the present invention comprises a matrix and a molecular sieve; the molecular sieve comprises an MFI type molecular sieve and an optional FAU type molecular sieve, and the MFI type molecular sieve is the ZSM-5 molecular sieve of the present invention.

[0118] In one embodiment of the present invention, in the catalyst provided by the present invention, based on the total dry weight of the catalyst, the matrix content is 50 to 78 weight%, the FAU type molecular sieve content is 0 weight% to 20 weight% or 1 to 20 weight% or 5 to 20 weight%, and the MFI type molecular sieve content is 10 weight% to 30 weight%.

[0119] In one embodiment of the present invention, in the catalyst provided by the present invention, based on the total weight of the catalyst, the catalyst comprises 45 to 80 wt% of the matrix, preferably 55 to 75 wt% of the matrix, and more preferably 60 to 70 wt% of the matrix.

[0120] In one embodiment of the present invention, the catalyst provided by the present invention comprises 20 to 55 wt% molecular sieve, preferably 25 to 45 wt% molecular sieve, and more preferably 30 to 40 wt% molecular sieve, based on the total weight of the catalyst.

[0121] In one embodiment of the present invention, in the catalyst provided by the present invention, the molecular sieve comprises the MFI type molecular sieve and optionally a FAU type molecular sieve.

[0122] In one embodiment of the present invention, according to the catalyst of the present invention, the FAU molecular sieve may be a Y molecular sieve. The Y molecular sieve may be, for example, one or more of REY, REHY, REUSY, USY, or modified Y zeolites with different silicon-aluminum ratios prepared by vapor phase chemical methods (SiCl4 dealumination and siliconization method), liquid phase chemical methods ((NH4)2SiF6 dealumination and siliconization method), or other methods.

[0123] In one embodiment of the present invention, in the catalyst according to the present invention, the weight ratio of the FAU molecular sieve to the ZSM-5 molecular sieve is 0.18-1.5:1, for example, 0.25-1.1:1, more preferably 0.3-1:1.

[0124] In one embodiment of the present invention, in the catalyst provided according to the present invention, the matrix may be one or more of natural clay, alumina matrix, silica matrix, and silica-alumina matrix. Preferably, the matrix comprises one or more of natural clay, alumina matrix, and silica matrix.

[0125] In one embodiment of the present invention, in the catalyst provided according to the present invention, the alumina matrix is, for example, one or more of pseudo-boehmite, alumina sol, and an alumina material. The alumina material is, for example, one or more of χ-Al2O3, η-Al2O3, γ-Al2O3, and ρ-Al2O3. The alumina matrix preferably includes one or more of pseudo-boehmite and alumina sol.

[0126] In one embodiment of the present invention, in the catalyst provided herein, the silicon oxide matrix is, for example, one or more of silica sol, silica gel, and water glass, preferably silica sol. The silica sol is one or more of neutral silica sol, acidic silica sol, or alkaline silica sol. The silica sol content in the catalyst, calculated as SiO2, is 0% to 15% by weight, for example, 5% to 10% by weight.

[0127] In one embodiment of the present invention, in the catalyst provided according to the present invention, the precursor of the amorphous silica-alumina can be selected from one or more of silica-alumina sol and silica-alumina gel.

[0128] In one embodiment of the present invention, in the catalyst provided by the present invention, the natural clay is selected from clays commonly used in cracking catalysts, such as one or more of kaolin, halloysite, montmorillonite, diatomaceous earth, and terpentine, preferably kaolin.

[0129] In one embodiment of the present invention, in the catalyst provided according to the present invention, the matrix includes a binder and an optional inorganic oxide matrix other than the binder. The binder is a matrix with a binding effect for the catalyst, for example, one or more of an alumina binder and a silica binder. The alumina binder may be pseudo-boehmite and / or aluminum sol; the silica binder may be one or more of silica sol and water glass, preferably silica sol, and the silica sol may be one or more of acidic silica sol, neutral silica sol, and alkaline silica sol. Based on the weight of the catalyst, the content of the binder in the catalyst is 10 to 40% by weight, for example, 20 to 35% by weight, calculated as oxide.

[0130] In one embodiment of the present invention, in the catalyst provided according to the present invention, the matrix includes a binder and may further include an inorganic oxide matrix other than the binder. Based on the total amount of the catalyst, the content of the inorganic oxide matrix other than the binder in the catalyst is 0 to 80% by weight on a dry basis, for example, 10% to 70% by weight. The inorganic oxide matrix other than the binder is selected from one or more inorganic oxide matrices commonly used in cracking catalysts. The inorganic oxide matrix other than the binder is a matrix that does not have a binding effect, preferably one or more of alumina, silica, amorphous silica-alumina and clay.

[0131] In one embodiment of the present invention, the catalyst comprises 30-60 wt%, for example, 35-48 wt%, of clay; 0-20 wt%, for example, 5-20 wt%, for example, 8-18 wt%, of Y-type molecular sieve; 10-30 wt%, for example, 15-25 wt%, of ZSM-5 molecular sieve; and 20-35 wt% of alumina binder. The alumina binder may be pseudo-boehmite (abbreviated as boehmite) and alumina sol. Preferably, the ratio of pseudo-boehmite to alumina sol, calculated on alumina basis, is 15-25:5-15, for example, 15-20:6-12.

[0132] There is no particular limitation on the method for preparing the catalyst of the present invention, and a method known in the art for preparing the catalyst using molecular sieves as active components can be used.

[0133] In one embodiment of the present invention, in the method for preparing the catalyst provided by the present invention, the substrate, molecular sieve, and water are slurried to form a slurry, which is then spray-dried. The substrate, molecular sieve, and water are slurried to form a slurry having a solids content of, for example, 15 to 40% by weight.

[0134] In the method for preparing the catalytic cracking catalyst provided by the present invention, there are no limitations on the slurrying method and conditions, and any slurrying conditions and methods known in the art may be used. Furthermore, there are no limitations on the spray drying method and conditions, and reference may be made to the spray drying methods and conditions of existing methods for preparing catalytic cracking catalysts, which are well known to those skilled in the art.

[0135] The catalyst of the present invention is used for catalytic cracking. Preferably, when catalytic cracking wax oil fraction, the catalyst of the present invention is used to increase the yield of propylene and butene.

[0136] Therefore, one embodiment of the present invention provides a method for catalytic cracking of wax oil distillates, wherein the catalyst of the present invention is used.

[0137] In one embodiment of the present invention, the following embodiments are provided:

[0138] Scheme 1. A catalytic cracking catalyst, characterized in that the catalytic cracking catalyst comprises 45-80% by weight of a matrix and 20-55% by weight of a molecular sieve, wherein the molecular sieve comprises an MFI molecular sieve and a FAU molecular sieve.

[0139] The MFI molecular sieve is a ZSM-5 molecular sieve, the particles of which are secondary particles formed by the aggregation of primary particles, the average particle size of the secondary particles being 100 to 900 nm; the average crystal size of the primary particles is no more than 100 nm;

[0140] After aging the ZSM-5 molecular sieve at 800° C. and 100% by volume of water vapor for 30 hours, the ZSM-5 molecular sieve has a crystal retention rate of not less than 90% and / or an acid retention rate as determined by NH3-TPD of not less than 5% relative to the ZSM-5 molecular sieve; and / or, a molecular sieve having a P / Al molar ratio of 1 is obtained by introducing phosphorus into the ZSM-5 molecular sieve, and after aging the molecular sieve having a P / Al molar ratio of 1 at 800° C. and 100% by volume of water vapor for 30 hours, the molecular sieve having a P / Al molar ratio of 1 has a crystal retention rate of not less than 90% and / or an acid retention rate as determined by NH3-TPD of not less than 30% relative to the molecular sieve having a P / Al molar ratio of 1 before aging;

[0141] Solution 2. The catalytic cracking catalyst according to Solution 1, wherein the average crystal size of the primary particles of the ZSM-5 molecular sieve is 10-100 nm, for example, 35-95 nm;

[0142] Scheme 3. The catalytic cracking catalyst according to Scheme 1, characterized in that the variance of the secondary particle size does not exceed 0.03 μm 2 For example, 0.001 to 0.03 μm 2 ;

[0143] Scheme 4. The catalytic cracking catalyst according to any one of Schemes 1 to 3, characterized in that the molecular sieve obtained by aging the ZSM-5 molecular sieve at 800° C. and 100% by volume of water vapor for 30 hours has a crystal retention of 90-99% and / or an acid retention of 32-48% or 5-48% as measured by NH3-TPD relative to the ZSM-5 molecular sieve;

[0144] and / or, introducing phosphorus into the ZSM-5 molecular sieve to obtain a molecular sieve with a P / Al molar ratio of 1, wherein the molecular sieve with a P / Al molar ratio of 1, after aging at 800° C. and 100% by volume of water vapor for 30 hours, has a crystal retention of 90-99% and / or an acid retention as measured by NH3-TPD of 32-48% relative to the molecular sieve with a P / Al molar ratio of 1 before aging;

[0145] Scheme 5. The catalytic cracking catalyst according to Scheme 1, wherein the relative crystallinity of the ZSM-5 molecular sieve is 50% to 80%;

[0146] Scheme 6. The catalytic cracking catalyst according to Scheme 1, characterized in that the silicon-aluminum ratio of the ZSM-5 molecular sieve is 20-60, calculated as the SiO2 / Al2O3 molar ratio; and / or the mesopore volume proportion of the ZSM-5 molecular sieve is 35%-86%, for example, 40%-70%;

[0147] Scheme 7. The catalytic cracking catalyst according to Scheme 1, characterized in that the preparation method of the ZSM-5 molecular sieve comprises the following steps:

[0148] (1) mixing an alkali, an optional aluminum source, a silicon source, water, and seed crystals to form a crystallization solution; the weak acid amount of the seed crystals is not greater than 35 ml / g; the weak acid amount is the volume of ammonia gas desorbed by NH3-TPD at 120-300°C converted to ammonia gas under standard conditions;

[0149] (2) performing step-by-step crystallization of the crystallization solution; wherein the first step crystallization temperature is 5° C. to 90° C., the first step crystallization time is 0.5 h or more, for example, 0.5 to 48 h, and the second step crystallization temperature is greater than 120° C.;

[0150] Recover ZSM-5 molecular sieve;

[0151] Scheme 8. The catalytic cracking catalyst according to Scheme 7 is characterized in that, in the preparation method of the ZSM-5 molecular sieve, in step (1), the silicon source is one or more of silica sol, white carbon black, tetramethyl orthosilicate, tetraethyl orthosilicate, sodium silicate, water glass, solid silica gel and sodium fluorosilicate; in step (1), the aluminum source is one or more of aluminum hydroxide, pseudo-boehmite, sodium metaaluminate, aluminum isopropoxide, aluminum sulfate, aluminum acetate, elemental aluminum, aluminum nitrate, aluminum sol, aluminum oxide and aluminum chloride; in step (1), the base is one or more of sodium carbonate, sodium hydroxide, sodium bicarbonate, potassium carbonate, potassium bicarbonate, potassium hydroxide, ammonia water and calcium hydroxide;

[0152] Scheme 9. The catalytic cracking catalyst according to any one of Schemes 7 to 8, characterized in that the pH value of the crystallization solution obtained in step (1) is 11 to 13.5;

[0153] Scheme 10. The preparation method according to Scheme 7, characterized in that the specific surface area of ​​the seed crystal is not less than 180m 2 / g is, for example, 180 to 500 m 2 / g; the amount of weak acid in the seed crystal is, for example, 0.5 to 30 ml / g or 0 to 20 ml / g;

[0154] Scheme 11. The catalytic cracking catalyst according to Scheme 7 or 10, characterized in that

[0155] In step (1), the seed crystal is one or more of ZSM-5 molecular sieve or a catalyst containing ZSM-5 molecular sieve;

[0156] The content of ZSM-5 molecular sieve in the catalyst containing ZSM-5 molecular sieve is preferably not less than 8% by weight; preferably, in the catalyst seed crystals containing ZSM-5 molecular sieve, the volume of particles with a particle diameter not exceeding 80 microns accounts for more than 95% of the total particle volume;

[0157] Scheme 12. The catalytic cracking catalyst according to Scheme 7 or 9, characterized in that, in the crystallization solution, the molar ratio of the mineralizer metal oxide, silicon source SiO2, aluminum source Al2O3, and H2O is (0.01-0.15):1:(0.000-0.025):(5-100), wherein the molar ratio of the silicon source SiO2 is obtained by converting the molar ratio of the silicon element in the silicon source into the molar ratio of SiO2, the molar ratio of the aluminum source Al2O3 is obtained by converting the molar ratio of the aluminum element in the aluminum source into the molar ratio of Al2O3, and the molar ratio of the mineralizer metal oxide is the total amount of the mineralizer metal elements in the alkali, aluminum source, and silicon source converted into the molar ratio of the mineralizer metal oxide, and the mineralizer metal is an alkali metal and / or an alkaline earth metal, the alkali metal oxide is calculated as M2O, and the alkaline earth metal oxide is calculated as M'O; M represents an alkali metal, and M' represents an alkaline earth metal;

[0158] The amount of the seed crystal added does not exceed 30% by weight of the amount of the silicon source SiO2, for example, 0.5 to 30% by weight, where the amount of the silicon source SiO2 is the amount of silicon element in the silicon source converted into SiO2;

[0159] Scheme 13. The catalytic cracking catalyst according to Scheme 7 or 12, characterized in that the mineralizer metal is an alkali metal, alkali metal is represented by M, the molar ratio of M2O:SiO2 is 0.05-0.15:1, the molar ratio of Al2O3:SiO2 is 0-0.04:1, and the molar ratio of H2O:SiO2 is 10-30:1; and the weight ratio of seed crystals / SiO2 is 0.05-0.15:1.

[0160] Scheme 14. The catalytic cracking catalyst according to Scheme 7, wherein the first crystallization temperature is 25-80°C, the first crystallization time is preferably 0.5-24 hours, and the second crystallization temperature is 150-180°C, the second crystallization time is preferably 10-60 hours.

[0161] After the first step of crystallization is completed, the heating rate to the second step of crystallization temperature can be 2 to 10°C / min;

[0162] Scheme 15. The catalytic cracking catalyst according to Scheme 7, characterized in that the recovery of the molecular sieve in step (3) comprises separation, washing, optional exchange of alkali metal, optional drying, and optional calcination; optionally, further comprising the step of introducing phosphorus;

[0163] Scheme 16. The catalytic cracking catalyst according to Scheme 1, characterized in that, based on the total dry weight of the catalytic cracking catalyst, the matrix content is 50% to 78% by weight, the FAU molecular sieve content is 5% to 20% by weight, and the MFI molecular sieve content is 10% to 30% by weight;

[0164] Scheme 17. The catalytic cracking catalyst according to any one of Schemes 1 to 16, characterized in that the ZSM-5 molecular sieve is a phosphorus-free ZSM-5 molecular sieve or a phosphorus-containing ZSM-5 molecular sieve, and the phosphorus content of the phosphorus-containing ZSM-5 molecular sieve is 0.5% to 15% by weight, for example, 1% to 10% by weight, calculated as P2O5;

[0165] Solution 18. The catalytic cracking catalyst according to Solution 17, characterized in that, based on the total dry weight of the catalytic cracking catalyst, the matrix content is 55% to 75% by weight, the FAU molecular sieve content is 5% to 16% by weight, and the ZSM-5 molecular sieve content is 12% to 30% by weight;

[0166] Scheme 19. The catalytic cracking catalyst according to Scheme 1, characterized in that the weight ratio of the FAU molecular sieve to the MFI molecular sieve is preferably 0.18 to 1.1:1; and the sodium oxide content in the ZSM-5 molecular sieve is preferably no more than 0.15% by weight, based on the weight of the ZSM-5 molecular sieve.

[0167] Solution 20. The catalytic cracking catalyst according to Solution 1, wherein the matrix is ​​one or more of natural clay, alumina matrix, and silica matrix;

[0168] The silicon oxide matrix is, for example, silica sol, which may be one or more of neutral silica sol, acidic silica sol, or alkaline silica sol;

[0169] The alumina matrix is, for example, one or more of pseudo-boehmite and aluminum sol;

[0170] The natural clay is, for example, one or more of kaolin, halloysite, montmorillonite, diatomaceous earth, and terpentine;

[0171] Scheme 21. The method for preparing the catalytic cracking catalyst according to any one of Schemes 1 to 20, comprising slurrying the matrix, molecular sieve, and water to form a slurry, and spray drying the slurry.

[0172] Scheme 22. Use of the catalytic cracking catalyst according to any one of Schemes 1 to 20 in the catalytic cracking of wax oil fractions.

[0173] Example

[0174] The present invention will be further described below by way of examples.

[0175] The following content provides different embodiments or examples so that those skilled in the art can implement accordingly with reference to the description text. Of course, these are merely examples, and are not intended to limit the present invention. The endpoints and any value of the scope disclosed in the present invention are not limited to this accurate scope or value, and these scopes or values ​​should be interpreted as comprising values ​​approaching these scopes or values. For numerical ranges, between the endpoint values ​​of each scope, between the endpoint values ​​of each scope and an independent point value, and between the independent point value, can be combined with each other and obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed in this article.

[0176] The reagents or materials used in the present invention can be purchased from commercial sources.

[0177] ZSM-5 as seed crystals was purchased from Nanhua Catalyst Co., Ltd.

[0178] The reagents used are as follows:

[0179] Silica sol (SiO2 content 30% by weight, pH 9.8),

[0180] Water glass (Na2O content is 80g / L, modulus is 3.3),

[0181] Tetraethyl orthosilicate (TEOS, analytical grade, concentration 99 wt%),

[0182] The industrial molecular sieve comes from Sinopec Catalyst Qilu Branch and is H-ZSM-5 molecular sieve.

[0183] Other raw materials were analytically pure reagents.

[0184] Analytical methods:

[0185] The relative crystallinity of ZSM-5 molecular sieve was measured by XRD. Powder X-ray diffraction (XRD) was measured on an X-ray diffractometer with Cu-Kα radiation (λ = 1.5406á) with a 2θ range of 5° to 50° and a scanning speed of 2° min -1 . See NB / SH / T6024-2021.

[0186] The size of molecular sieve grains and molecular sieve secondary particles was measured by SEM. The measurement method is as follows: the maximum size (also called particle length or particle size) of 10 randomly measured molecular sieves is averaged to obtain the average particle size of the secondary particles. The maximum size (also called grain size or primary particle size) of 10 randomly measured crystal grains is averaged to obtain the average grain size. The uniformity of the average particle size of the secondary particles is characterized by variance, and the variance is calculated as follows:

[0187] S 2is the sample variance, X is the variable, is the sample mean, and n is the number of samples.

[0188] The acid content is measured using the NH3-TPD method. The test method is as follows: 0.1 g of the sample is pretreated in a helium atmosphere by heating to 550°C and holding for 1 hour at a helium flow rate of 50 ml / min. The temperature is then lowered to 120°C and a 10% (volume) NH3 / He mixture is introduced at a flow rate of 50 ml / min. After 10 minutes, the mixture is switched to He and purged with helium at a flow rate of 50 ml / min for 60 minutes. The sample is then desorbed at a heating rate of 10°C / min to 550°C. The gas flow rates are converted to those under standard conditions.

[0189] For the molecular sieves in the examples of the present invention and the comparative examples, the crystal retention and acid retention were measured. The crystal retention and acid retention were measured as follows:

[0190] Phosphorus was introduced into the synthesized molecular sieve in a P / Al ratio of 1 for phosphorus modification. The phosphorus-containing molecular sieve after phosphorus modification was hydrothermally aged. The acid content and relative crystallinity of the phosphorus-containing molecular sieve before and after hydrothermal aging were measured, and the acid content retention and crystallinity retention were calculated as the crystallinity retention and acid content retention of the molecular sieve in the examples and comparative examples.

[0191] When measuring the acid retention and crystallization retention, the method for introducing phosphorus for phosphorus modification is as follows: the molecular sieve and diammonium hydrogen phosphate are impregnated with phosphorus in equal volumes according to P / Al=1 (amount of substance), dried, and calcined at 550°C for 3h to obtain the modified phosphorus-containing molecular sieve (also called "unaged molecular sieve (after phosphorus modification)").

[0192] The hydrothermal aging conditions are as follows: the phosphorus-modified molecular sieve is treated under 800° C. and 100% by volume hydrothermal conditions for 30 h, and is named “aged molecular sieve (phosphorus-modified)”;

[0193] Acid retention = acid content of aged molecular sieve (after phosphorus modification) / acid content of unaged molecular sieve (after phosphorus modification) × 100%

[0194] Crystallinity retention = relative crystallinity of the aged molecular sieve (after phosphorus modification) / relative crystallinity of the unaged molecular sieve (after phosphorus modification) × 100%.

[0195] In each comparative example and embodiment, the method for determining the pore structure is as follows: the total pore volume of the molecular sieve is determined according to the adsorption isotherm, and then the micropore volume of the molecular sieve is determined from the adsorption isotherm according to the t-plot method, and the secondary pore volume is obtained by subtracting the micropore volume from the total pore volume. The mesoporous specific surface area and specific surface area (total specific surface area), pore volume, and pore size distribution are measured using a low-temperature nitrogen adsorption capacity method. Using an ASAP2420 adsorption instrument from Micromeritics, USA, the sample is vacuum degassed at 100°C and 300°C for 0.5h and 6h, respectively, and a N2 adsorption and desorption test is performed at a temperature of 77.4K. The adsorption and desorption amounts of nitrogen gas on the test sample under different specific pressure conditions are tested to obtain an N2 adsorption-desorption isotherm. The BET specific surface area (total specific surface area) is calculated using the BET formula, and the micropore area is calculated using t-plot. The calculation of pore volume and pore size distribution can be found in RIPP 151-90 standard method "Determination of pore volume and pore size distribution of catalysts by nitrogen adsorption capacity method" in Petrochemical Analytical Methods (RIPP Test Method) (edited by Yang Cuiding et al., Science Press, published in 1990).

[0196] Example 1

[0197] In the crystallization solution, the alkali, silicon source, and aluminum source are configured in the following molar ratio: 0.11M2O:SiO2:0.01Al2O3:20H2O; where M represents Na, the silicon source is silica sol (SiO2 content is 30% by weight), the aluminum source is aluminum sulfate, and the alkali is sodium hydroxide. The above ratio does not include seed crystals. The seed crystals are ZSM-5 molecular sieve seed crystals with a specific surface area of ​​320m 2 / g, the amount of weak acid is 15ml / g, and the seed crystal / SiO2=0.1 (weight ratio).

[0198] Sodium hydroxide and aluminum sulfate were added to water, mixed thoroughly, and then silica sol was added. After stirring for 1 hour, a seed ZSM-5 molecular sieve was added to obtain a crystallization solution. The solution was then allowed to stand at 25°C for 8 hours, then heated to 175°C at a heating rate of 5°C / min for crystallization for 28 hours with a stirring speed of 300 rpm. After crystallization, the solution was subjected to solid-liquid separation, washing (using deionized water at a solid-liquid weight ratio of 1:10), drying, and calcination (at 550°C for 3 hours, the same below) to obtain the nanosized ZSM-5 molecular sieve Z-1.

[0199] XRD (Figure 1) determined that the crystals of Z-1 were ZSM-5 molecular sieves. The SEM scanning electron microscopy results showed that the average particle size of Z-1 (average particle size of secondary particles) was 650nm, and it was grown from nano-crystals with an average grain size of 92nm.

[0200] As can be seen from Table 1, the crystal retention and acid retention of the ZSM-5 molecular sieve Z-1 synthesized in the present invention are 97% and 38%, respectively, while the results of the comparative ZSM-5 molecular sieve (conventional crystalline molecular sieve, designated C (provided by Sinopec Catalyst Qilu Branch, with a silicon-aluminum ratio of 25)) measured under the same conditions are 81% and 31%. Compared with the comparative molecular sieve, the ZSM-5 molecular sieve prepared in the present invention has significantly higher crystal retention and acid retention, and excellent hydrothermal stability.

[0201] Example 2

[0202] The crystallization materials (silicon source, aluminum source, alkali) are prepared in the crystallization solution according to the following ratio (molar ratio): 0.13M2O:SiO2:0.014Al2O3:20H2O. The above ratio does not include the seed crystal; the silicon source is water glass, the aluminum source is sodium aluminate (caustic ratio of 1.4), and the alkali is sodium hydroxide. The seed crystal is a ZSM-5 molecular sieve seed crystal with a specific surface area of ​​275m 2 / g, the amount of weak acid was 10ml / g, and the seed crystal / SiO2 ratio was 0.2 (by weight). Sodium hydroxide and sodium aluminate were added to water, mixed thoroughly, and then water glass was added. After stirring for 1 hour, a seed ZSM-5 molecular sieve was added. The mixture was then stirred at 30°C for 10 hours at 300 rpm. The temperature was then raised (at a heating rate of 5°C / min) to 160°C for crystallization for 48 hours at 300 rpm. After crystallization, the mixture was subjected to solid-liquid separation, washing (using deionized water at a solid-liquid ratio of 1:10, the same below), drying, and calcination (calcination temperature 550°C, calcination time 3 hours, the same below) to obtain the nanosized ZSM-5 molecular sieve Z-2. The SEM image (Figure 2) shows an average particle size of 350nm, grown from nanocrystals with an average grain size of approximately 50nm.

[0203] Example 3

[0204] The crystallization materials (silicon source, aluminum source, alkali) in the crystallization solution are configured according to the following ratio (molar ratio): 0.08M2O:SiO2:0.04Al2O3:30H2O; where M represents alkali metal, the silicon source is water glass, the aluminum source is aluminum nitrate, and the alkali is potassium hydroxide. The seed crystal is ZSM-5 molecular sieve with a specific surface area of ​​350m 2 / g, the amount of weak acid is 16ml / g, and the seed crystal / SiO2 = 0.15 (by weight). Potassium hydroxide and aluminum nitrate are added to water successively, mixed evenly, then water glass is added and stirred for 1 hour before adding seed ZSM-5 molecular sieve. The mixture is then stirred at 70°C for 20 hours at a stirring speed of 200 rpm, then heated to 170°C (at a heating rate of 5°C / min) and crystallized for 20 hours at a constant stirring speed. After crystallization, solid-liquid separation, washing, drying, and calcination are performed to obtain nanosized ZSM-5 molecular sieve Z-3 with an average particle size of 810nm, grown from nanocrystals with an average grain size of approximately 60nm.

[0205] Example 4

[0206] The crystallization materials (referring to silicon source, aluminum source, alkali, and water) are prepared into a crystallization solution according to the following molar ratio: 0.1M2O:SiO2:0.02Al2O3:10H2O; wherein the silicon source is silica sol, the aluminum source is sodium aluminate, and the alkali is sodium hydroxide. The seed crystal is ZSM-5 molecular sieve with a specific surface area of ​​302m 2 / g, the amount of weak acid is 0.9ml / g, and the seed crystal / SiO2 = 0.12 (by weight). Sodium hydroxide and sodium aluminate are added to water successively, mixed evenly, and then silica sol is added. After stirring for 1.5 hours, ZSM-5 seed crystals are added. The mixture is then stirred at 70°C for 24 hours at a stirring speed of 200 rpm, and then the temperature is raised to 170°C for crystallization for 30 hours at a constant stirring speed. After crystallization, solid-liquid separation, washing, drying, and calcination are performed to obtain nano-sized ZSM-5 molecular sieve Z-4. The average particle size of Z-4 is 590nm, and the average crystallite diameter is 82nm. XRD (Figure 3) shows that the Z-4 ​​crystals are ZSM-5 molecular sieve.

[0207] Comparative Example 1

[0208] The crystallization materials are prepared into a crystallization solution according to the following ratio (molar ratio): 0.11M2O:SiO2:0.01Al2O3:20H2O; where M represents an alkali metal, the silicon source is silica sol, the aluminum source is aluminum sulfate, and the alkali is sodium hydroxide. The specific surface area of ​​the seed crystal (ZSM-5 molecular sieve) is 301m 2 / g, weak acid amount is 37ml / g, seed crystal / SiO2=0.1 (weight). Sodium hydroxide and aluminum sulfate are added to water successively, mixed evenly, silica sol is added, stirred for 1 hour, and then seed crystal ZSM-5 is added. After that, it is allowed to stand at 25°C for 8 hours, and then the temperature is raised to 175°C for crystallization for 28 hours, with a stirring speed of 300rpm. After crystallization, small-grain ZSM-5 molecular sieve D-1 is obtained through solid-liquid separation, washing, drying and calcination. The results of the SEM scanning electron microscopy (Figure 4) show that the average particle size of the synthesized ZSM-5 is about 1820nm, which is significantly larger than Z-1. For D-1, the crystal retention and acid retention were measured to be 90% and 30% respectively. Compared with Z-1, the crystal retention and acid retention of this comparative molecular sieve are significantly lower, indicating that its hydrothermal stability is inferior to that of Z-1.

[0209] Comparative Example 2

[0210] The method of Example 1 was followed, wherein one-step crystallization was adopted and crystallization was carried out at 175° C. for 28 hours.

[0211] The crystallization material (silicon source is silica sol (SiO2 content is 30% by weight, the same below), aluminum source is aluminum sulfate, and alkali is sodium hydroxide) is prepared into a crystallization solution according to the following molar ratio: 0.11M2O:SiO2:0.01Al2O3:20H2O; where M represents Na, and the seed crystal is not included in the above ratio. ZSM-5 molecular sieve seed crystals, the specific surface area of ​​the seed crystals is 320m 2 / g, the amount of weak acid is 15 ml / g, and the seed crystal / SiO2 = 0.1 (weight ratio). Sodium hydroxide and aluminum sulfate are added to water successively, mixed evenly, and then silica sol is added. After stirring for 1 hour, a seed crystal ZSM-5 molecular sieve is added to obtain a crystallization solution; then the temperature is raised to 175 ° C at a heating rate of 5 ° C / min for crystallization for 28 hours, and the stirring speed is 300 rpm. After crystallization, ZSM-5 molecular sieve D-2 is obtained by solid-liquid separation, washing (eluting with deionized water at a solid-liquid weight ratio of 1:10), drying, and calcination (calcined at 550 ° C for 3 hours).

[0212] Comparative Example 3

[0213] The crystallization materials were prepared into a crystallization solution according to the following molar ratio: 0.11M2O:SiO2:0.01Al2O3:20H2O; where M represents an alkali metal, the silicon source is silica sol (SiO2 content is 30% by weight), the aluminum source is aluminum sulfate, and the alkali is sodium hydroxide. The seed crystals are ZSM-5 molecular sieve seed crystals with a specific surface area of ​​320m 2 / g, the amount of weak acid is 15ml / g, and the seed crystal / SiO2=0.1 (weight ratio).

[0214] Sodium hydroxide and aluminum sulfate were added to water, mixed thoroughly, and then silica sol was added. After stirring for 1 hour, seed ZSM-5 crystals were added to obtain a crystallization solution. The solution was then allowed to stand at 100°C for 8 hours, then heated to 175°C at a heating rate of 5°C / min for crystallization for 28 hours with stirring at 300 rpm. After crystallization, solid-liquid separation, washing, drying, and calcination were performed to obtain small-grain ZSM-5 molecular sieve D-3. The XRD results are shown in Figure 5. The average particle size of the synthesized ZSM-5 was approximately 1000 nm, significantly larger than that of Z-1, and the crystallinity was only 16.5%. The crystal retention and acidity retention of D-3 were measured to be 83% and 28%, respectively. Compared with Z-1, the crystal retention and acidity retention of this comparative molecular sieve were significantly lower, indicating that its hydrothermal stability was inferior to that of Z-1.

[0215] The properties of the molecular sieves synthesized in Examples 1-4 and Comparative Examples 1-3 are shown in Table 1.

[0216] Table 1

[0217] As shown in Table 1, the molecular sieve provided by the present invention has a relatively small particle size, less than 0.9 microns, and a relatively small particle length variance, indicating a more uniform particle size distribution. Furthermore, the ZSM-5 molecular sieve provided by the present invention has a higher hydrothermal stability.

[0218] Examples 5 to 8, Comparative Examples 4 to 5

[0219] The ZSM-5 molecular sieves Z-1, Z2, Z3, and Z4 prepared in Examples 1 to 4, D-1 prepared in Comparative Example 1, and industrial ZSM-5 molecular sieves were modified with phosphorus to obtain phosphorus-containing ZSM-5 molecular sieves, which were respectively designated as 7.5P / Z-1, 7.5P / Z-2, 7.5P / Z-3, 7.5P / Z-4, 7.5P / D-1, and 7.5P / C.

[0220] The phosphorus modification method is as follows:

[0221] The ammonium exchange steps are as follows: add ammonium sulfate (12% by weight of the molecular sieve) to water (8 times by weight of the molecular sieve dry basis), dissolve, add the molecular sieve, and then stir at 70°C for 1.5 hours. Then filter, wash twice with deionized water (8 times by weight of the molecular sieve dry basis), dry, and then calcine at 550°C for 5 hours.

[0222] The steps for loading ZSM-5 molecular sieve with 7.5 wt% phosphorus (calculated as P2O5) were as follows: 20.6 g of (NH4)2HPO4 was dissolved in 100 g of water, 100 g of the ZSM-5 molecular sieve obtained in the ammonium exchange step was added for impregnation, and then the mixture was dried at 110°C and calcined at 550°C for 2 hours. The resulting phosphorus-containing ZSM-5 molecular sieves were designated as 7.5P / Z-1, 7.5P / Z-2, 7.5P / Z-3, 7.5P / Z-4, 7.5P / D-1, and 7.5P / C, respectively. Their properties are shown in Table 2.

[0223] Table 2

[0224] Examples 9 to 13

[0225] The phosphorus-containing ZSM-5 molecular sieve prepared in Examples 5 to 8 was used to prepare a catalytic cracking catalyst.

[0226] In the following examples and comparative examples:

[0227] The kaolin used was an industrial product of China Kaolin Company, with a solid content of 75% by weight;

[0228] The pseudo-boehmite used was produced by Shandong Aluminum Plant and had an alumina content of 65% by weight;

[0229] Alumina sol was produced by Sinopec Catalyst Co., Ltd. Qilu Branch, and its alumina content was 21% by weight;

[0230] Ultrastable Y molecular sieve, with a SiO2:Al2O3 molar ratio of 6.5, a rare earth oxide mass content of 2.9%, and a unit cell constant of 2.439nm; provided by Sinopec Catalyst Co., Ltd. Qilu Branch.

[0231] Preparation method of catalytic cracking catalyst:

[0232] (1) A certain amount of pseudo-boehmite and a certain amount of water were weighed and mixed uniformly. 35 wt % concentrated hydrochloric acid (chemically pure, produced by Beijing Chemical Plant) was added with stirring, with an acid-to-aluminum ratio (the molar ratio of HCl to pseudo-boehmite calculated as alumina) of 0.18. The resulting mixture was heated to 50° C. and aged for 1.5 hours to obtain an aged pseudo-boehmite slurry. The aged pseudo-boehmite slurry had an alumina content of 12 wt %.

[0233] (2) A fixed amount of ZSM-5 molecular sieve 7.5P / Z-1 or 7.5P / Z-2 or 7.5P / Z-3 or 7.5P / Z-4, a fixed amount of aluminum sol or silica sol, and / or the above-mentioned aged pseudo-boehmite slurry, a fixed amount of ultrastable Y molecular sieve, and a fixed amount of kaolin are mixed with deionized water to prepare a slurry with a solid content of 33% by weight, and the mixture is spray-dried.

[0234] Table 3 shows the type and amount of ZSM-5 used in each step, as well as the amounts of Y molecular sieve, alumina sol, silica sol, and kaolin. Table 4 shows the compositions of Catalysts A1-A5 (the amounts of each component are based on the total weight of the catalyst). The amounts of Y-type zeolite, binder, ZSM-5 molecular sieve, and kaolin in the catalyst compositions were calculated.

[0235] Example 14

[0236] According to the method of Example 5, Z-1 molecular sieve was used to prepare a phosphorus-containing ZSM-5 molecular sieve with a phosphorus content (calculated as P2O5) of 1% by weight, which was recorded as 1P / Z-1.

[0237] A catalyst was prepared according to the method of Example 9, catalyst number A6, except that 1P / Z-1 molecular sieve was used instead of 7.5P / Z-1 molecular sieve.

[0238] Comparative Example 6

[0239] According to the catalyst preparation method of Example 9, the phosphorus-containing ZSM-5 molecular sieve 7.5P / D-1 prepared in Comparative Example 4 was prepared into a microsphere catalyst. Catalyst number DB1. Table 3 shows the type and amount of ZSM-5 used in step (2), and the amounts of Y molecular sieve, aluminum sol, silica sol, and kaolin used (taking the preparation of 1 kg of catalyst as an example). Table 4 shows the composition of catalyst DB1 (wherein the content of each component is based on the total weight of the catalyst).

[0240] Comparative Example 7

[0241] Following the catalyst preparation method of Example 9, the molecular sieve 7.5P / C, obtained by phosphorus-modifying the industrial molecular sieve prepared in Comparative Example 5, was prepared into a microsphere catalyst. Catalyst number DB2. Table 3 shows the type and amount of ZSM-5 used, as well as the amounts of Y molecular sieve, alumina sol, pseudoboehmite (abbreviated as alumina), silica sol, and kaolin (based on the preparation of 1 kg of catalyst). Table 4 shows the composition of catalyst DB2 (the amounts of each component are based on the total weight of the catalyst).

[0242] Catalysts A1-A6, DB1, and DB2 were aged at 800°C in 100% steam volume for 17 hours. Their catalytic cracking performance was evaluated in a small fixed fluidized bed reactor (ACE). The cracked gas and product oil were collected and analyzed by gas chromatography. The feed oil properties for the ACE experiments are shown in Table 5. The catalyst loading was 9 g, and the weight hourly space velocity (WHV) was 8 h. -1 ,The evaluation conditions and evaluation results are shown in Table 6.

[0243] Table 3

[0244] The above is the ingredients for preparing 1kg catalyst

[0245] Table 4

[0246] Table 5

[0247] Table 6

[0248] As can be seen from the results listed in Tables 1 and 6, the ZSM-5 molecular sieve provided by the present invention has high hydrothermal stability. When the catalytic cracking catalyst prepared by combining it with the Y molecular sieve as an active component is used for the conversion of saturated hydrocarbon-rich wax oil distillate, the yields of propylene and butene can be significantly improved.

[0249] Those skilled in the art should note that the embodiments described in the present invention are merely exemplary and that various other replacements, changes, and improvements may be made within the scope of the present invention.

Claims

1. A catalyst, characterized in that Based on the total weight of the catalyst, the catalyst comprises 45 to 80 wt% of a matrix and 20 to 55 wt% of a molecular sieve, wherein the molecular sieve comprises an MFI type molecular sieve and an optional FAU type molecular sieve. The MFI type molecular sieve is a ZSM-5 molecular sieve, and the ZSM-5 molecular sieve is a secondary particle formed by the aggregation of primary particles; The proportion of aluminum forming Al-pair in the ZSM-5 molecular sieve to the total framework aluminum is no more than 20%, preferably no more than 18%.

2. The catalyst according to claim 1, wherein The ZSM-5 molecular sieve satisfies at least one of the following conditions: The silicon-aluminum ratio of the ZSM-5 molecular sieve is 20 to 60, for example, 20 to 50 or 20 to 40, calculated as the SiO2 / Al2O3 molar ratio; The mesopore volume of the ZSM-5 molecular sieve is 35% to 86%, for example, 40% to 70% or 42% to 65%; The crystal retention of the ZSM-5 molecular sieve is not less than 90%, preferably 90-99% or 91-98%; The acid retention of the ZSM-5 molecular sieve measured by NH3-TPD is not less than 5%, preferably not less than 30%, more preferably 32-48% or 35-42%; The average crystal size of the primary particles of the ZSM-5 molecular sieve is 10 to 100 nm, preferably 35 to 95 nm or 50 to 95 nm; The variance of the average particle size of the secondary particles does not exceed 0.03 μm 2 , for example, 0.001 to 0.03 μm 2 ; The average particle size of the secondary particles is 100 to 900 nm, preferably 200 to 700 nm.

3. The catalyst according to claim 1 or 2, wherein The ZSM-5 molecular sieve is a phosphorus-containing ZSM-5 molecular sieve, and the f value of the phosphorus distribution in the ZSM-5 molecular sieve satisfies: 55%≤f≤85%, and the f=P2 / P1×100%, wherein P1 represents the phosphorus mass content of any crystal surface of the molecular sieve grains measured by the XPS method, and P2 represents the phosphorus mass content of any crystal surface of the molecular sieve grains after ion sputtering for 100s measured by the XPS method.

4. The catalyst according to claim 3, wherein The phosphorus-containing ZSM-5 molecular sieve satisfies at least one of the following conditions: The crystal retention of the phosphorus-containing ZSM-5 molecular sieve is not less than 90%, preferably 90-99%; The acid retention of the phosphorus-containing ZSM-5 molecular sieve measured by NH3-TPD is not less than 30%, preferably 32 to 48%; The phosphorus content in the phosphorus-containing ZSM-5 molecular sieve is 0.5% to 15% by weight, for example, 1 to 10% by weight, calculated as P2O5.

5. The catalyst according to any one of claims 1 to 4, wherein Based on the total weight of the catalyst, the matrix content is 50-78 weight %, the FAU molecular sieve content is 0-20 weight % or 1-20 weight % or 5-20 weight %, and the MFI molecular sieve content is 10-30 weight %.

6. The catalyst according to any one of claims 1 to 5, characterized in that The ZSM-5 molecular sieve is manufactured by a preparation method comprising the following steps: (1) mixing an alkali, a silicon source, water, a seed crystal, and an optional aluminum source to form a crystallization solution; wherein the amount of the weak acid in the seed crystal does not exceed 35 ml / g; (2) crystallizing the obtained crystallization solution in steps; wherein the first step crystallization temperature is 5° C. to 90° C., the first step crystallization time is 0.5 h or more, for example, 0.5 to 48 h, and the second step crystallization temperature is greater than 120° C., the second step crystallization time is 3 to 72 h; (3) Recovering ZSM-5 molecular sieve.

7. The catalyst according to claim 6, characterized in that The method for preparing the ZSM-5 molecular sieve further comprises step (4), wherein the obtained ZSM-5 molecular sieve is subjected to phosphorus modification to obtain a phosphorus-containing ZSM-5 molecular sieve.

8. The catalyst according to claim 6 or 7, characterized in that Step (1) of the method for preparing the ZSM-5 molecular sieve satisfies at least one of the following conditions: The silicon source is one or more of silica sol, white carbon black, tetramethyl orthosilicate, tetraethyl orthosilicate, sodium silicate, water glass, solid silica gel and sodium fluorosilicate; the aluminum source is one or more of aluminum hydroxide, pseudo-boehmite, sodium metaaluminate, aluminum isopropoxide, aluminum sulfate, aluminum acetate, elemental aluminum, aluminum nitrate, aluminum sol, aluminum oxide and aluminum chloride; the alkali is one or more of sodium carbonate, sodium hydroxide, sodium bicarbonate, potassium carbonate, potassium bicarbonate, potassium hydroxide, ammonia water and calcium hydroxide; In the crystallization solution, the molar ratio of the mineralizer metal oxide, silicon source SiO2, aluminum source Al2O3 and H2O is (0.01-0.15):1:(0-0.055):(5-100), preferably (0.05-0.15):1:(0.005-0.04):(10-50), wherein the molar ratio of the silicon source SiO2 is obtained by converting the molar ratio of the silicon element in the silicon source into the molar ratio of SiO2. The amount of substance of the aluminum source Al2O3 is obtained by converting the amount of substance of the aluminum element in the aluminum source into the amount of substance of Al2O3. The amount of substance of the mineralizer metal oxide is the total amount of substance of the mineralizer metal element in the alkali, aluminum source and silicon source converted into the amount of substance of the mineralizer metal oxide. The mineralizer metal is an alkali metal and / or an alkaline earth metal. The oxide of the alkali metal is calculated as M2O, and the oxide of the alkaline earth metal is calculated as M'O; M represents an alkali metal, and M' represents an alkaline earth metal. The mineralizer metal is an alkali metal, denoted by M, and the ratio of the alkali metal to the silicon source is 0.05-0.15:1, preferably 0.1-0.15:1, calculated as the molar ratio of M2O:SiO2; the ratio of the aluminum source to the silicon source is 0-0.04:1, preferably 0.005-0.02:1, calculated as the molar ratio of Al2O3:SiO2; the ratio of water to the silicon source is 10-30:1, preferably 10-50:1, calculated as the molar ratio of H2O:SiO2; and the ratio of the seed crystal to the silicon source is 0.05-0.3:1, preferably 0.1-0.25:1, calculated as the weight ratio of the seed crystal / SiO2; The amount of the seed crystal added does not exceed 30% by weight of the amount of the silicon source SiO2, for example, 0.5 to 30% by weight, where the amount of the silicon source SiO2 is the amount of silicon element in the silicon source converted into SiO2; The pH value of the crystallization solution obtained in step (1) is 11.0 to 13.5; The specific surface area of ​​the seed crystal is not less than 180m 2 / g is, for example, 180 to 500 m 2 / g; The weak acid amount of the seed crystal is less than 30 ml / g or 0 to 20 ml / g; The seed crystals contain ZSM-5 molecular sieve, preferably the content of ZSM-5 molecular sieve in the seed crystals is not less than 8% by weight, preferably the seed crystals are ZSM-5 molecular sieve; In the seed crystals, the volume of particles with a particle size not exceeding 80 microns accounts for more than 95% of the total particle volume.

9. The catalyst according to any one of claims 6 to 8, characterized in that Step (2) of the method for preparing the ZSM-5 molecular sieve satisfies at least one of the following conditions: The first step crystallization temperature is 25-80°C, and the first step crystallization time is 0.5-24h; The second step crystallization temperature is higher than 120°C and lower than 200°C, preferably 150°C to 180°C, and the second step crystallization time is 10 to 60 hours; After the first step of crystallization is completed, the heating rate from the temperature of the second step of crystallization to the temperature of the second step of crystallization is 2 to 10°C / min.

10. The catalyst according to any one of claims 6 to 9, characterized in that The step (3) of the method for preparing the ZSM-5 molecular sieve comprises separation, washing, optionally exchanging alkali metal, optionally drying and optionally calcining, thereby recovering the molecular sieve.

11. The catalyst according to any one of claims 7 to 10, characterized in that The step (4) of the preparation method of the ZSM-5 molecular sieve is carried out as follows: 1) For the ZSM-5 molecular sieve obtained in step (3), use ammonium salt to perform hydrothermal exchange, and then dry and roast. Preferably, the ZSM-5 molecular sieve, ammonium salt and water are exchanged at a weight ratio of 1:0.2 to 1.0:5 to 20 at 60 to 95 ° C for 0.5 to 2 hours, and then dried. The ammonium salt is at least one selected from ammonium chloride, ammonium nitrate, ammonium carbonate, ammonium bicarbonate, ammonium oxalate, ammonium sulfate, and ammonium bisulfate. 2) contacting the ammonium exchange product in step 1) with a phosphorus-containing compound, and then drying and calcining. Preferably, the ammonium exchange product in step 1) is immersed in an aqueous solution of a phosphorus-containing compound, and then drying and calcining. The phosphorus-containing compound is at least one selected from orthophosphoric acid, phosphorous acid, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, aluminum phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, and pyrophosphoric acid.

12. The catalyst according to any one of claims 1 to 11, wherein The weight ratio of the FAU molecular sieve to the MFI molecular sieve is 0.18-1.5:1, for example, 0.25-1.1:1, more preferably 0.3-1:1; based on the weight of the ZSM-5 molecular sieve, the sodium oxide content in the ZSM-5 molecular sieve does not exceed 0.15% by weight.

13. The catalyst according to any one of claims 1 to 12, wherein The matrix is ​​one or more of natural clay, aluminum oxide matrix, and silicon oxide matrix. The silicon oxide matrix is, for example, silica sol, and the silica sol can be one or more of neutral silica sol, acidic silica sol, and alkaline silica sol; the aluminum oxide matrix is, for example, one or more of pseudo-boehmite and aluminum sol; the natural clay is, for example, one or more of kaolin, halloysite, montmorillonite, diatomaceous earth, and terpentine.

14. The method for preparing the catalyst according to any one of claims 1 to 13, wherein Slurrying the matrix, molecular sieve and water to form a slurry, and then spray drying, wherein the MFI type molecular sieve is a ZSM-5 molecular sieve, and the ZSM-5 molecular sieve is a secondary particle formed by aggregation of primary particles; The proportion of aluminum forming Al-pair in the ZSM-5 molecular sieve to the total framework aluminum is no more than 20%, preferably no more than 18%.

15. The preparation method according to claim 14, characterized in that Based on the total weight of the matrix and the molecular sieve, the matrix content is 45-80 weight %, and the molecular sieve content is 20-55 weight %. The molecular sieve comprises an MFI type molecular sieve and an optional FAU type molecular sieve.

16. Use of the catalyst according to any one of claims 1 to 13 in catalytic cracking of wax oil fractions.

17. A method for catalytic cracking of wax oil fractions, wherein: In the catalytic cracking of gas oil distillate, the catalyst according to any one of claims 1 to 13 is used.

Images