Catalytic cracking catalysts, their preparation methods and applications

Abstract

This invention relates to the field of catalytic cracking catalyst preparation, and discloses a catalytic cracking catalyst, its preparation method, and its application. The catalytic cracking catalyst comprises a molecular sieve, a binder, and clay; based on the total mass of the catalyst, the mass content of the molecular sieve is 60-85%, the mass content of the clay is 5-20%, and the mass content of the binder is 10-35%; the mesopore size of the catalyst is 3-50 nm; in the catalyst, the volume of mesopores with a pore size of 6-10 nm accounts for 8-30% of the total mesopore volume; in the catalyst, the volume of mesopores with a pore size of 30-35 nm accounts for 10-30% of the total mesopore volume. This catalyst exhibits excellent catalytic performance and, when applied to catalytic cracking reactions, especially naphtha catalytic cracking reactions, demonstrates high conversion rates and low-carbon olefin yields.

Description

Technical Field

[0001] This invention relates to the field of catalytic cracking catalyst preparation, specifically to a catalytic cracking catalyst, its preparation method, and its application. Background Technology

[0002] Currently, the most common method for producing ethylene and propylene is steam cracking, with naphtha being the most frequently used feedstock. However, steam cracking of naphtha has drawbacks such as high reaction temperatures, demanding process conditions, large CO2 release, and significant losses. In recent years, catalytic cracking has been developed as a process for producing low-carbon olefins from petroleum hydrocarbons, and numerous reports have been published on related catalysts.

[0003] CN114425417A discloses a naphtha catalytic cracking catalyst, its preparation method and application. The catalyst contains 50-85% by weight of a support and 15-50% by weight of a core-shell molecular sieve. However, the preparation method of the core-shell molecular sieve is relatively complicated.

[0004] CN1413244A discloses a method that combines modified mesoporous phosphate material as a catalyst with a primary catalytic cracking material to catalytically crack sulfur-containing hydrocarbon feedstocks to prepare small-molecule hydrocarbon mixtures. However, the catalyst has poor hydrothermal stability, resulting in low feedstock conversion and product yield.

[0005] CN1274342A discloses a molecular sieve with a high silicon-to-aluminum ratio and a pore size between 0.5 and 0.65 nanometers as a catalyst to prepare ethylene propylene from olefin-containing light hydrocarbons, but the yield of ethylene propylene is low.

[0006] CN105582999B discloses a catalyst for catalytic cracking of naphtha to produce propylene and its preparation method. Based on the total weight of the catalyst, the catalyst contains 50-95% by weight of molecular sieves and 5-50% by weight of matrix. The molecular sieves include a first molecular sieve and a second molecular sieve. The first molecular sieve has a ten-membered ring two-dimensional elliptical pore structure, and the second molecular sieve has a twelve-membered ring pore structure. It achieves a high diene yield, but requires the use of multiple molecular sieves as active centers, resulting in relatively high cost. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems existing in the prior art and provide a catalytic cracking catalyst, its preparation, and its application. This catalyst has excellent catalytic performance and is applied to catalytic cracking reactions, especially naphtha catalytic cracking reactions, exhibiting high conversion rates and low-carbon olefin yields.

[0008] To achieve the above objectives, the present invention provides a catalytic cracking catalyst, the catalyst comprising a molecular sieve, a binder, and clay; based on the total mass of the catalyst, the mass content of the molecular sieve is 60-85%, the mass content of the clay is 5-20%, and the mass content of the binder is 10-35%.

[0009] The catalyst has a mesopore size of 3-50 nm;

[0010] In the catalyst, the volume of mesopores with a pore size of 6-10 nm accounts for 8-30% of the total mesopore volume;

[0011] In the catalyst, mesopores with a pore size of 30-35 nm account for 10-30% of the total mesopore volume. A second aspect of the present invention provides a method for preparing a catalytic cracking catalyst, the method comprising:

[0012] (1) The molecular sieve, the second suspension containing clay and the first binder precursor are pulped to obtain the first slurry;

[0013] (2) The first slurry is mixed with at least a portion of the second binder precursor to obtain a second slurry with a viscosity not greater than 0.1 Pa·s;

[0014] (3) The second slurry and the third binder precursor are mixed to obtain a third slurry with a viscosity of not less than 1 Pa·s;

[0015] (4) The third slurry is aged with an amphiphilic block polymer to obtain a fourth slurry;

[0016] (5) The fourth slurry is spray-dried and then calcined;

[0017] through 27 Al MAS NMR characterization showed that the ratio of the resonance signal peak area at a chemical shift of 45±1 ppm to the resonance signal peak area at a chemical shift of 53±1 ppm was no greater than 1.5.

[0018] The third aspect of this invention provides the application of the catalytic cracking catalyst described in the first aspect or the catalytic cracking catalyst prepared by the method described in the second aspect in a catalytic cracking reaction.

[0019] The beneficial effects of the present invention through the above technical solution include:

[0020] The catalyst of this invention has a high molecular weight sieve content and a wide mesopore size distribution, resulting in excellent catalytic performance. When applied to catalytic cracking reactions, particularly naphtha cracking, the catalyst exhibits high conversion rates and low-carbon olefin yields. Attached Figure Description

[0021] Figure 1 This is a mesopore distribution diagram of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2;

[0022] Figure 2 This is a macropore distribution diagram of the catalyst prepared in Example 1. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] The dry basis mentioned in this invention refers to the product obtained by calcination at 550°C for 2 hours.

[0025] The present invention provides a catalytic cracking catalyst, the catalyst comprising a molecular sieve, a binder, and clay; based on the total mass of the catalyst, the mass content of the molecular sieve is 60-85%, the mass content of the clay is 5-20%, and the mass content of the binder is 10-35%.

[0026] The catalyst has a mesopore size of 3-50 nm;

[0027] In the catalyst, the volume of mesopores with a pore size of 6-10 nm accounts for 8-30% of the total mesopore volume;

[0028] In the catalyst, the volume of mesopores with a pore size of 30-35 nm accounts for 10-30% of the total mesopore volume.

[0029] Existing catalytic cracking catalysts typically have narrow mesopore distributions, generally at the 6-10 nm level, which results in poor catalytic activity due to the difficulty in exposing active sites. In contrast, the catalyst described in this invention has a wider mesopore distribution, which facilitates the exposure of molecular sieve active sites and the unobstructed flow of catalyst channels, thereby improving the catalyst's catalytic activity.

[0030] To further improve the catalytic performance of the catalyst, preferably, based on the total mass of the catalyst, the mass content of molecular sieve is 60-70%, the mass content of clay is 5-20%, and the mass content of binder is 16-35%.

[0031] The content of each component in the catalyst described in this invention is calculated by the feed ratio.

[0032] According to the present invention, preferably, the mesopore size of the catalyst is 6-50 nm.

[0033] The mesopore size of the catalyst described in this invention was measured by the N2 adsorption BET method.

[0034] The catalyst of this invention has abundant mesopores, which is beneficial for improving its catalytic activity. According to this invention, preferably, the mesopore volume of the catalyst accounts for 40-70% of the total pore volume of the catalyst, more preferably 45-60%.

[0035] The pore volume distribution of the catalyst described in this invention was measured by the N2 adsorption BET method and mercury porosimetry.

[0036] According to the present invention, preferably, the macropore size of the catalyst is 90-435 nm.

[0037] The pore size of the macropores in the catalyst described in this invention was measured by mercury porosimetry.

[0038] According to the present invention, preferably, the porosity of the catalyst is not greater than 66%, and more preferably 50-65%. This preferred embodiment ensures both the proximity of the active centers of the molecular sieve and the mechanical strength of the catalyst.

[0039] The porosity of the catalyst described in this invention was measured by mercury intrusion porosimetry.

[0040] According to the present invention, preferably, the average crystallite size of the molecular sieve is 100-500 nm, more preferably 200-300 nm. This preferred embodiment increases the contact probability between the reactants and the catalytically active sites, thereby improving the catalyst's reactivity.

[0041] In this invention, when the grain is spherical, the grain size refers to the grain diameter; when the grain is quasi-spherical, the grain size refers to the diameter of its largest circumscribed circle.

[0042] The average grain size described in this invention is determined by transmission electron microscopy. Specifically, 10 molecular sieve grains are randomly selected, their grain sizes are measured, and the average value is taken.

[0043] According to the present invention, preferably, the SiO2 / Al2O3 molar ratio of the molecular sieve is 25-200, more preferably 25-100. This preferred embodiment is beneficial for improving the catalytic activity of the catalyst.

[0044] According to the present invention, preferably, via 27 Al MAS NMR characterization showed that the ratio of the characteristic peak area of ​​the molecular sieve at a chemical shift of 45 ± 1 ppm to the characteristic peak area at a chemical shift of 53 ± 1 ppm was no greater than 1.5, preferably 0.35-1.5. This preferred embodiment resulted in a catalyst with good hydrothermal stability.

[0045] The present invention allows for a wide range of molecular sieve types, as long as they meet the aforementioned characteristics. Preferably, the molecular sieve is selected from at least one of ZSM-5, IM-5, and ZSM-22 molecular sieves.

[0046] The present invention allows for a wide range of clay types, which can be conventional choices in the art. Preferably, the clay is selected from at least one of kaolin, halloysite, montmorillonite, and kaolin.

[0047] According to the present invention, preferably, the adhesive comprises a first adhesive, a second adhesive, and a third adhesive.

[0048] According to the present invention, preferably, the first binder is obtained by calcining at least one of boehmite, hydrated alumina having a monohydrate structure, hydrated alumina having a trihydrate structure, hydrated alumina having a Bayer structure, γ-alumina, η-alumina, θ-alumina and x-alumina.

[0049] The present invention does not have any particular limitation on the source of the first adhesive, which can be obtained commercially or prepared by conventional methods.

[0050] According to the present invention, preferably, the second binder is obtained by calcining aluminum sol.

[0051] According to the present invention, preferably, the third binder is obtained by calcining aluminum phosphate glue.

[0052] The present invention does not particularly limit the calcination conditions. For example, the calcination conditions can be the calcination conditions in the preparation methods described below.

[0053] According to the present invention, preferably, the mass ratio of the second adhesive to the first adhesive is 1-4, more preferably 1.7-4.

[0054] According to the present invention, preferably, the mass ratio of the second adhesive to the third adhesive is 0.3-1, more preferably 0.3-0.8.

[0055] The present invention uses three binders in a specific ratio, which is beneficial to obtaining the catalyst with a porous structure described in the present invention.

[0056] According to the present invention, preferably, the aluminum-chlorine ratio of the aluminum sol is not higher than 1.4, and more preferably 1.2-1.3. This preferred embodiment ensures the binding performance of the binder while minimizing the degree of damage to the molecular sieve framework, which is beneficial for improving the reaction activity of the catalyst.

[0057] The aluminum-chlorine ratio of the aluminum sol described in this invention was determined by X-ray fluorescence spectroscopy.

[0058] The present invention does not have any particular limitation on the source of the aluminum sol, which can be obtained commercially or prepared by conventional methods.

[0059] According to the present invention, preferably, the phosphorus aluminum gel has a network structure.

[0060] The structure of the aluminum phosphate gel described in this invention was determined by transmission electron microscopy.

[0061] In existing technologies, aluminum phosphate gels generally have a dispersed spherical nanoparticle structure, which suffers from poor adhesion and structural instability. However, during their research, the inventors discovered that aluminum phosphate gels with a network structure possess both excellent adhesion properties and a stable framework, which is beneficial for improving the mechanical strength of catalysts.

[0062] According to the present invention, preferably, the mass ratio of Al2O3 to P2O5 in the aluminum phosphate gel is 0.25-0.35. This preferred embodiment ensures that the aluminum phosphate gel has a rich network structure.

[0063] The mass ratio of Al2O3 to P2O5 in the aluminum phosphate gel of the present invention was determined by X-ray fluorescence spectroscopy.

[0064] According to the present invention, preferably, the pH of the phosphoaluminum gel is 1-3, more preferably 2-3. This preferred embodiment ensures the structure and stability of the phosphoaluminum gel binder, while also ensuring the stability of the molecular sieve structure, further contributing to improved catalyst reactivity and mechanical strength.

[0065] The present invention does not impose any particular limitation on the preparation method of the above-mentioned aluminum phosphate colloid, as long as the aluminum phosphate colloid with the above-mentioned composition and characteristics can be prepared. In order to further improve the catalytic performance of the catalyst, the present invention also provides a preparation method of the above-mentioned aluminum phosphate colloid.

[0066] According to the present invention, preferably, the preparation method of the aluminum phosphate adhesive includes: mixing an acid-soluble aluminum precursor with water to form a slurry, and then adding a phosphoric acid solution at 45-55°C to react and obtain the aluminum phosphate adhesive.

[0067] According to the present invention, preferably, the reaction conditions include: a temperature of 75-85°C and a time of 1-2 hours.

[0068] In the preparation method of the phosphorus aluminum gel of the present invention, by controlling the addition temperature of phosphoric acid, and preferably further controlling the reaction conditions, the composition and characteristics of the obtained phosphorus aluminum gel meet the above requirements, which is beneficial to the obtained catalyst having excellent catalytic performance and high mechanical strength.

[0069] The present invention does not have a particular limitation on the amount of the acid-soluble aluminum precursor and the phosphoric acid solution used, but the mass ratio of Al2O3 to P2O5 in the obtained aluminum phosphate gel is 0.25-0.35.

[0070] The present invention does not have a particular limitation on the amount of water used, as long as the pH of the aluminum phosphate gel is within the above-mentioned range.

[0071] This invention offers a wide range of choices for acid-soluble aluminum precursors, which can be conventional choices in the field. Preferably, the acid-soluble aluminum precursor is selected from at least one of boehmite, alumina, aluminum hydroxide, aluminum isopropoxide, and aluminum isobutoxide, with boehmite being the most preferred.

[0072] A second aspect of the present invention provides a method for preparing a catalytic cracking catalyst, the method comprising:

[0073] (1) The molecular sieve, the second suspension containing clay and the first binder precursor are pulped to obtain the first slurry;

[0074] (2) The first slurry is mixed with at least a portion of the second binder precursor to obtain a second slurry with a viscosity not greater than 0.1 Pa·s;

[0075] (3) The second slurry and the third binder precursor are mixed to obtain a third slurry with a viscosity of not less than 1 Pa·s;

[0076] (4) The third slurry is aged with an amphiphilic block polymer to obtain a fourth slurry;

[0077] (5) The fourth slurry is spray-dried and then calcined;

[0078] through 27 Al MAS NMR characterization showed that the ratio of the resonance signal peak area at a chemical shift of 45±1 ppm to the resonance signal peak area at a chemical shift of 53±1 ppm was no greater than 1.5.

[0079] In existing technologies, the molecular sieve content of spray-formed catalysts is relatively low, generally not exceeding 40 wt%. This is mainly because it is necessary to ensure that the mechanical strength of the catalyst meets the requirements of catalytic cracking reactions. When the molecular sieve content is too high, spray forming becomes more difficult, and it also leads to an excessively high catalyst attrition index (above 10% / h), resulting in poor catalyst stability. The catalyst obtained by the method provided in this invention overcomes the above-mentioned defects. The resulting catalyst not only meets the mechanical strength requirements of catalytic cracking reactions but also has a high molecular sieve content and a wide mesopore distribution. When applied to catalytic cracking reactions, especially naphtha catalytic cracking reactions, it exhibits higher reactant conversion rates and higher ethylene and propylene yields.

[0080] In this invention, the viscosity of the second slurry is not greater than 0.1 Pa·s, preferably 0.05-0.1 Pa·s. This preferred embodiment is advantageous for obtaining a homogeneous catalyst (i.e., a uniform distribution of all components).

[0081] In this invention, the viscosity of the third slurry is not less than 1 Pa·s, preferably 1-2 Pa·s. This preferred embodiment is beneficial for improving the mechanical strength of the catalyst.

[0082] The viscosity described in this invention is measured using a viscometer.

[0083] The present invention does not impose any particular limitations on the specific conditions of pulping (mentioned above and below) in the preparation method, and conventional methods in the art can be used, and no limitation is made here.

[0084] According to the present invention, preferably, the amounts of clay, molecular sieve, and binder precursor are such that, based on the total mass of the catalyst, the mass content of clay is 5-20%, the mass content of molecular sieve is 60-85%, and the mass content of binder is 10-35%, wherein the binder is the sum of a first binder, a second binder, and a third binder.

[0085] More preferably, the amounts of clay, molecular sieve, and binder precursor are such that, based on the total mass of the catalyst, the mass content of clay is 5-20%, the mass content of molecular sieve is 60-70%, and the mass content of binder is 16-35%, wherein the binder is the sum of the first binder, the second binder, and the third binder.

[0086] According to the present invention, preferably, the dry basis mass ratio of the second binder precursor to the first binder precursor is 1-4, more preferably 1.7-4.

[0087] According to the present invention, preferably, the dry basis mass ratio of the second binder precursor to the third binder precursor is 0.3-1, more preferably 0.3-0.8.

[0088] According to the present invention, preferably, the average grain size of the molecular sieve is 100-500 nm, more preferably 200-300 nm.

[0089] According to the present invention, preferably, the SiO2 / Al2O3 molar ratio of the molecular sieve is 25-200, more preferably 25-100.

[0090] According to the present invention, preferably, via 27Al MAS NMR characterization showed that the ratio of the characteristic peak area of ​​the molecular sieve at a chemical shift of 45±1 ppm to the characteristic peak area at a chemical shift of 53±1 ppm was 0.35-1.5.

[0091] The present invention allows for a wide range of molecular sieve types, as long as they meet the aforementioned characteristics. Preferably, the molecular sieve is selected from at least one of ZSM-5, IM-5, and ZSM-22 molecular sieves.

[0092] The present invention allows for a wide range of clay types, which can be conventional choices in the art. Preferably, the clay is selected from at least one of kaolin, halloysite, montmorillonite, and kaolin.

[0093] According to the present invention, preferably, the first binder precursor is selected from at least one of boehmite, hydrated alumina having a monohydrate structure, hydrated alumina having a trihydrate structure, hydrated alumina having a Bayer structure, γ-alumina, η-alumina, θ-alumina and x-alumina.

[0094] According to the present invention, preferably, the second binder precursor is aluminum sol.

[0095] According to the present invention, preferably, the aluminum-chlorine ratio of the aluminum sol is not higher than 1.4, and more preferably 1.2-1.3.

[0096] The present invention does not have any particular limitation on the source of the aluminum sol, which can be obtained commercially or prepared by conventional methods.

[0097] According to the present invention, preferably, the third binder precursor is aluminum phosphate adhesive.

[0098] According to the present invention, preferably, the phosphorus aluminum gel has a network structure.

[0099] According to the present invention, preferably, the mass ratio of Al2O3 to P2O5 in the phosphorus aluminum gel is 0.25-0.35.

[0100] According to the present invention, preferably, the pH of the aluminum phosphate gel is 1-3, more preferably 2-3.

[0101] According to the present invention, preferably, the preparation method of the aluminum phosphate adhesive includes: mixing an acid-soluble aluminum precursor with water to form a slurry, and then adding a phosphoric acid solution at 45-55°C to react and obtain the aluminum phosphate adhesive.

[0102] According to the present invention, preferably, the reaction conditions include: a temperature of 75-85°C and a time of 1-2 hours.

[0103] According to the present invention, preferably, the acid-soluble aluminum precursor is selected from at least one of boehmite, alumina, aluminum hydroxide, aluminum isopropoxide, and aluminum isobutoxide, and preferably boehmite.

[0104] The present invention does not impose any particular limitation on the order of adding the molecular sieve, the clay-containing second suspension, and the first binder precursor in step (1). They can be added separately or together. The embodiment of the present invention uses the method of adding them together as an example.

[0105] Preferably, the molecular sieve is provided in the form of a first suspension.

[0106] The present invention allows for a wide range of choices regarding the type of the first liquid medium in the first suspension, and can be a conventional choice in the art. Preferably, the first liquid medium is water and / or an organic solvent, with water being the most preferred.

[0107] The present invention does not have a particular limitation on the amount of the first liquid medium in the first suspension, but the solid content in the first suspension is within 30-40 wt%.

[0108] According to the present invention, preferably, the second suspension is obtained by slurrying clay, a second liquid medium, and optionally the remaining portion of a second binder precursor. In this preferred embodiment, the clay exhibits good fluidity while maintaining a high solids content in the second suspension.

[0109] According to the present invention, preferably, the dry basis mass of the remaining second binder precursor is 5-15% of the dry basis mass of the clay.

[0110] The present invention allows for a wide range of choices for the second liquid medium in the second suspension, which can be conventional choices in the field.

[0111] According to a preferred embodiment of the present invention, the second liquid medium is of the same type as the first liquid medium.

[0112] The present invention does not have any particular limitation on the amount of the second liquid medium in the second suspension, but the solid content in the second suspension is within 28-38 wt%.

[0113] Preferably, the first binder precursor is provided in the form of a third suspension.

[0114] Preferably, the method for preparing the third suspension includes: first, slurrying the first binder precursor with the third liquid medium, and then mixing it with acid.

[0115] Preferably, the acid is an inorganic acid, more preferably hydrochloric acid and / or nitric acid. All of the above substances are conventional choices in the art and are commercially available.

[0116] Preferably, the weight ratio of the acid to the first binder precursor on a dry basis is 0.1-1:1.

[0117] The present invention allows for a wide range of choices for the third liquid medium in the third suspension, which can be conventional choices in the field.

[0118] According to a preferred embodiment of the present invention, the third liquid medium is of the same type as the first liquid medium.

[0119] The present invention does not have a particular limitation on the amount of the third liquid medium in the third suspension, but the solid content in the third suspension is within 10-25 wt%.

[0120] According to the present invention, preferably, the aging conditions in step (4) include: a temperature of 50-85°C, preferably 60-80°C; and a time of 0.5-4h, preferably 1-2h.

[0121] This invention ages the third slurry and the amphiphilic block polymer under specific conditions, which is more conducive to improving the reactivity of the catalyst described in this invention. When the aging temperature is below the range described in this invention, it is difficult to obtain a rich mesoporous structure; when the aging temperature is above the range described in this invention, the binder in the catalyst slurry is prone to agglomeration, which is not conducive to subsequent spray drying.

[0122] It should be noted that if the aging time described in this invention is too long, the binder is prone to agglomeration, which is not conducive to subsequent spray drying.

[0123] According to the present invention, preferably, the mass amount of the amphiphilic block polymer is 5-30% of the third slurry on a dry basis, more preferably 10-20%.

[0124] The addition of the amphiphilic block polymer in step (4) of the present invention is beneficial to obtaining the catalyst with the pore structure described in the first aspect of the present invention.

[0125] The amphiphilic block polymer described in this invention refers to a block compound containing both hydrophilic and lipophilic segments, which is a well-known definition in the art.

[0126] The present invention allows for a wide selection of block polymers, which can be various amphiphilic block polymers commonly found in the art. To improve the catalytic performance of the catalyst, more preferably, the block polymer is selected from at least one of polyethylene glycol-b-polypropylene glycol, polystyrene-b-polyacrylic acid, and polystyrene-b-polyethylene glycol.

[0127] The present invention does not have any particular limitation on the source of the above-mentioned amphiphilic block polymers. They can be prepared by conventional methods in the art or obtained commercially.

[0128] The present invention does not impose any particular limitation on the specific conditions of spray drying in step (5), and can refer to conventional methods in the art. The present invention does not impose any limitation here.

[0129] The present invention does not particularly limit the roasting conditions in step (5), and can refer to conventional methods in the art. Preferably, the roasting conditions in step (5) include: a temperature of 400-800℃ and a time of 1-12h. The roasting is generally carried out in an air atmosphere, which may include a flowing atmosphere or a stationary atmosphere.

[0130] In this invention, the terms "first," "second," and "third" do not limit the substances and operations, but are only used to distinguish the substances introduced in different steps and the operations performed in different stages.

[0131] The third aspect of the present invention provides the application of the catalytic cracking catalyst described in the first aspect or the catalytic cracking catalyst prepared by the method described in the second aspect in a catalytic cracking reaction, preferably in the application of naphtha catalytic cracking reaction.

[0132] The present invention does not impose any particular limitations on the conditions for the above-mentioned catalytic cracking reaction, and can be carried out with reference to conventional methods in the art.

[0133] To better illustrate the stability of the catalyst described in this invention in catalytic cracking reaction applications, it is subjected to hydrothermal aging before use.

[0134] The hydrothermal aging temperature of existing catalytic cracking catalysts is generally no higher than 800℃, and the time is relatively short, generally not exceeding 17 hours. The hydrothermal aging conditions described in this invention are more stringent, better reflecting the actual industrial application. Preferably, the hydrothermal aging conditions include: a temperature of 820-850℃ and a time of 20-72 hours.

[0135] Preferably, the hydrothermal aging is carried out under conditions of 100% water vapor.

[0136] The present invention will be described in detail below through embodiments.

[0137] In the following examples, the aluminum sol is a commercially available product from Sinopec Catalyst Company Qilu Branch, with a solid content of 21.5% by weight;

[0138] Boehmite is a commercially available product from Shandong Aluminum Plant, with a solid content of 66.9% by weight.

[0139] ZSM-5 molecular sieve is a commercially available product from Tianjin Nanhua Catalyst Co., Ltd., with a dry basis weight of 97.8%.

[0140] ZSM-22 molecular sieve is a commercially available product from Tianjin Nanhua Catalyst Co., Ltd., with a dry basis weight of 98.5%.

[0141] Kaolin is a commercially available product of Suzhou Kaolin Company, with a dry basis weight of 84.6%.

[0142] Polyethylene glycol-b-polypropylene glycol is a commercially available product from Sigma-Aldrich, brand name 438197.

[0143] Polystyrene-b-polyacrylic acid is a commercially available product from Sigma-Aldrich, brand name 776351.

[0144] Polystyrene-b-polyethylene glycol is a commercially available product of Xi'an Qiyue Biotechnology Co., Ltd., with the brand name Q-0000920.

[0145] Preparation Examples 1-3 illustrate the preparation of the aluminum phosphate gel described in this invention.

[0146] Preparation Example 1

[0147] 0.55 kg of boehmite and 1.45 kg of deionized water were weighed and mixed evenly. The mixture was then heated to 50 °C, and 2.00 kg of phosphoric acid (85 wt%) was added. The mixture was heated to 80 °C and reacted for 90 min to prepare aluminum phosphate gel. The aluminum phosphate gel has a network structure, an Al2O3 to P2O5 mass ratio of 0.3, and a pH of 2.

[0148] Preparation Example 2

[0149] 0.51 kg of boehmite and 1.41 kg of deionized water were weighed and mixed evenly. The mixture was then heated to 45°C, and 2.00 kg of phosphoric acid (85 wt%) was added. The mixture was then heated to 80°C and reacted for 60 min to prepare aluminum phosphate gel. The aluminum phosphate gel has a network structure, an Al2O3 to P2O5 mass ratio of 0.28, and a pH of 2.2.

[0150] Preparation Example 3

[0151] 0.64 kg of boehmite and 1.45 kg of deionized water were weighed and mixed evenly, then heated to 55°C. Next, 2.00 kg of phosphoric acid (85 wt%) was added, and the mixture was heated to 75°C and reacted for 60 min to prepare aluminum phosphate gel. The aluminum phosphate gel has a network structure, an Al₂O₃ to P₂O₅ mass ratio of 0.35, and a pH of 2.5.

[0152] Example 1

[0153] A ZSM-5 molecular sieve suspension with a solid content of 33 wt% was prepared by uniformly mixing 6.65 kg of ZSM-5 molecular sieve with deionized water. A kaolin suspension with a solid content of 38 wt% was prepared by uniformly mixing 1.18 kg of kaolin, 0.47 kg of alumina sol, and deionized water. A boehmite suspension with a solid content of 17 wt% was prepared by uniformly mixing 0.45 kg of boehmite with deionized water, followed by the addition of hydrochloric acid (the weight ratio of the acid to the first binder precursor on a dry basis was 0.13). The kaolin suspension, boehmite suspension, and molecular sieve suspension were then mixed for 15 min to obtain a first slurry. 2.33 kg of alumina sol was added to the first slurry and mixed for 5 min to obtain a second slurry. 4 kg of aluminum phosphate colloid prepared in Preparation Example 1 was added to the second slurry and mixed for 5 min to obtain a third slurry. 200 mL of polyethylene glycol-b-polypropylene glycol aqueous solution was added to the third slurry, then heated to 60 °C and aged for 1 h. The mixture was then cooled to room temperature to obtain the fourth slurry. The fourth slurry was spray-dried and then calcined at 550 °C for 2 h to obtain the catalyst, denoted as A. Some conditions during catalyst preparation are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0154] The mesopore distribution of the catalyst prepared in Example 1 is given as an example. Figure 1 As shown, the catalyst exhibits a relatively wide mesoporous distribution in the 6-50 nm range.

[0155] The macropore distribution of the catalyst prepared in Example 1 is given as an example, such as Figure 2 As shown, the catalyst exhibits a significant macroporous distribution in the 95-432 nm range.

[0156] Example 2

[0157] A ZSM-22 molecular sieve suspension with a solid content of 36 wt% was prepared by uniformly mixing 12.26 kg of ZSM-22 molecular sieve with deionized water. A kaolin suspension with a solid content of 38 wt% was prepared by uniformly mixing 3.54 kg of kaolin, 1.40 kg of alumina sol, and deionized water. A boehmite suspension with a solid content of 21 wt% was prepared by uniformly mixing 0.45 kg of boehmite with deionized water, followed by the addition of hydrochloric acid (the weight ratio of the acid to the first binder precursor on a dry basis was 0.12). The kaolin suspension, boehmite suspension, and molecular sieve suspension were then mixed for 15 min to obtain a first slurry. 4.18 kg of alumina sol was added to the first slurry and mixed for 5 min to obtain a second slurry. 3.92 kg of aluminum phosphate colloid prepared in Preparation Example 2 was added to the second slurry and mixed for 5 min to obtain a third slurry. 225 mL of a polystyrene-b-polyacrylic acid aqueous solution was added to the third slurry, then heated to 60 °C and aged for 1.5 h. The mixture was then cooled to room temperature to obtain the fourth slurry. The fourth slurry was spray-dried and then calcined at 550 °C for 2 h to obtain the catalyst, denoted as B. Some conditions during catalyst preparation are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0158] Example 3

[0159] A ZSM-5 molecular sieve suspension with a solid content of 31 wt% was prepared by uniformly mixing 10.74 kg of ZSM-5 molecular sieve with deionized water. A kaolin suspension with a solid content of 30 wt% was prepared by uniformly mixing 1.40 kg of kaolin, 0.50 kg of alumina sol, and deionized water. A boehmite suspension with a solid content of 20 wt% was prepared by uniformly mixing 0.8 kg of boehmite with deionized water, followed by the addition of concentrated hydrochloric acid (the weight ratio of the acid to the first binder precursor on a dry basis was 0.1). A boehmite suspension with a solid content of 20 wt% was prepared. The kaolin suspension, boehmite suspension, and molecular sieve suspension were then mixed and stirred for 15 min to obtain a first slurry. 5.14 kg of alumina sol was added to the first slurry and stirred for 5 min to obtain a second slurry. 4.09 kg of aluminum phosphate colloid prepared in Preparation Example 3 was added to the second slurry and stirred for 5 min to obtain a third slurry. 150 mL of polystyrene-b-polyethylene glycol aqueous solution was added to the third slurry, then heated to 75 °C and aged for 1.5 h. The mixture was then cooled to room temperature to obtain the fourth slurry. The fourth slurry was spray-dried and then calcined at 550 °C for 2 h to obtain the catalyst, denoted as C. Some conditions during catalyst preparation are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0160] Comparative Example 1

[0161] A ZSM-5 molecular sieve suspension with a solid content of 33 wt% was prepared by uniformly mixing 4.21 kg of ZSM-5 molecular sieve with deionized water. A kaolin suspension with a solid content of 38 wt% was prepared by uniformly mixing 1.15 kg of kaolin, 0.47 kg of alumina sol, and deionized water. A boehmite suspension with a solid content of 17 wt% was prepared by uniformly mixing 0.55 kg of boehmite with deionized water, followed by the addition of hydrochloric acid (the weight ratio of the acid to the first binder precursor on a dry basis was 0.13). The kaolin suspension, boehmite suspension, and molecular sieve suspension were then mixed and stirred for 15 min to obtain the first slurry. 4.66 kg of alumina sol was added to the first slurry and stirred for 5 min to obtain the second slurry. The second slurry was spray-dried and then calcined at 550℃ for 2 hours to obtain the catalyst, denoted as D. Some conditions during catalyst preparation are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0162] The mesoporous distribution of catalyst D, such as Figure 1 As shown, there is no pore size distribution in the 6-50nm mesopore range.

[0163] Comparative Example 2

[0164] The method of Example 2 was followed, except that the polystyrene-b-polyacrylic acid aqueous solution was not added. Instead, the third slurry was directly spray-dried and calcined to obtain the catalyst, denoted as E. Some conditions in the catalyst preparation process are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0165] The mesoporous distribution of catalyst E, such as Figure 1 As shown, there is no pore size distribution in the 6-50nm mesopore range.

[0166] Comparative Example 3

[0167] The process was carried out according to Example 1, except that 2.33 kg of aluminum phosphate colloid was added to the second slurry and 4 kg of aluminum sol was added to the third slurry to obtain the catalyst, denoted as F. Some conditions during catalyst preparation are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0168] Table 1

[0169]

[0170] Note: The silicon-aluminum molar ratio is the same as the SiO2 / Al2O3 molar ratio.

[0171] Table 2

[0172]

[0173] Note: X represents the percentage of mesopore volume with a pore size of 6-10 nm to the total mesopore volume, in %.

[0174] Y represents the proportion of mesopore volume with a pore size of 30-35 nm to the total mesopore volume, %.

[0175] Test Example 1

[0176] The catalysts AF prepared in the examples and comparative examples were subjected to hydrothermal aging treatment at 820℃ and 100% steam for 20 hours, and then evaluated for naphtha cracking reaction. Detailed evaluation conditions for the micro-reaction were as follows: catalyst dosage 9.0 g, feedstock Yanshan Changding naphtha (composition shown in Table 3), catalyst-to-naphtha ratio (mass ratio of catalyst to naphtha) 10, and reaction temperature 600℃. Evaluation data after 90 seconds of reaction are detailed in Table 4.

[0177] Table 3

[0178]

[0179] Note: C Num This refers to the number of carbon atoms.

[0180] Table 4

[0181]

[0182]

[0183] As shown in Table 4, the catalyst described in this invention exhibits higher reactant conversion and higher ethylene and propylene yields when applied to naphtha catalytic cracking. Table 4 also demonstrates that the catalyst described in this invention possesses good hydrothermal stability.

[0184] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalytic cracking catalyst, characterized in that, The catalyst comprises molecular sieves, binders, and clay; based on the total mass of the catalyst, the mass content of molecular sieves is 60-85%, the mass content of clay is 5-20%, and the mass content of binders is 10-35%. The catalyst has a mesopore size of 3-50 nm; In the catalyst, the volume of mesopores with a pore size of 6-10 nm accounts for 8-30% of the total mesopore volume; In the catalyst, the volume of mesopores with a pore size of 30-35 nm accounts for 10-30% of the total mesopore volume; The adhesive includes a first adhesive, a second adhesive, and a third adhesive; The first binder is obtained by calcining at least one of the following: boehmite, hydrated alumina with a monohydrate structure, hydrated alumina with a trihydrate structure, hydrated alumina with a Bayer structure, γ-alumina, η-alumina, θ-alumina and x-alumina. The second binder is obtained by calcining aluminum sol; The third binder is obtained by calcining phosphorus aluminum glue; The preparation method of the catalytic cracking catalyst includes: (1) The molecular sieve, the second suspension containing clay and the first binder precursor are pulped to obtain the first slurry; (2) The first slurry is mixed with at least a portion of the second binder precursor to obtain a second slurry with a viscosity not greater than 0.1 Pa·s; (3) The second slurry and the third binder precursor are mixed to obtain a third slurry with a viscosity of not less than 1 Pa·s; (4) The third slurry is aged with an amphiphilic block polymer to obtain a fourth slurry; (5) The fourth slurry is spray-dried and then calcined; through 27 Al MAS NMR characterization showed that the ratio of the resonance signal peak area at a chemical shift of 45±1 ppm to the resonance signal peak area at a chemical shift of 53±1 ppm was no greater than 1.

5.

2. The catalyst according to claim 1, wherein, Based on the total mass of the catalyst, the mass content of molecular sieve is 60-70%, the mass content of clay is 5-20%, and the mass content of binder is 16-35%.

3. The catalyst according to claim 1, wherein, The catalyst has a mesopore size of 6-50 nm.

4. The catalyst according to claim 1, wherein, The mesopore volume of the catalyst accounts for 40-70% of the total pore volume of the catalyst.

5. The catalyst according to claim 4, wherein, The mesopore volume of the catalyst accounts for 45-60% of the total pore volume of the catalyst.

6. The catalyst according to claim 1, wherein, The catalyst has a macropore size of 90-435 nm.

7. The catalyst according to claim 1, wherein, The porosity of the catalyst is no greater than 66%.

8. The catalyst according to claim 7, wherein, The catalyst has a porosity of 50-65%.

9. The catalyst according to claim 1, wherein, The average crystal size of the molecular sieve is 100-500 nm; The SiO2 / Al2O3 molar ratio of the molecular sieve is 25-200.

10. The catalyst according to claim 9, wherein, The average crystal size of the molecular sieve is 200-300 nm; The SiO2 / Al2O3 molar ratio of the molecular sieve is 25-100.

11. The catalyst according to claim 1, wherein, through 27 Al MAS NMR characterization showed that the ratio of the characteristic peak area of ​​the molecular sieve at a chemical shift of 45±1 ppm to the characteristic peak area at a chemical shift of 53±1 ppm was 0.35-1.

5.

12. The catalyst according to claim 1, wherein, The molecular sieve is selected from at least one of ZSM-5 molecular sieve, IM-5 molecular sieve and ZSM-22 molecular sieve.

13. The catalyst according to any one of claims 1-12, wherein, The mass ratio of the second adhesive to the first adhesive is 1-4; The mass ratio of the second adhesive to the third adhesive is 0.3-1.

14. The catalyst according to claim 13, wherein, The mass ratio of the second adhesive to the third adhesive is 0.3-0.8; The mass ratio of the second adhesive to the first adhesive is 1.7-4.

15. The catalyst according to any one of claims 1-12, wherein, The aluminum-chlorine ratio of the aluminum sol is not higher than 1.

4.

16. The catalyst according to claim 15, wherein, The aluminum sol has an aluminum-chlorine ratio of 1.2-1.

3.

17. The catalyst according to any one of claims 1-12, wherein, The phosphorus aluminum gel has a network structure.

18. The catalyst according to any one of claims 1-12, wherein, The mass ratio of Al2O3 to P2O5 in the phosphorus aluminum gel is 0.25-0.

35.

19. The catalyst according to any one of claims 1-12, wherein, The pH of the phosphate aluminum gel is 1-3.

20. The catalyst according to claim 19, wherein, The pH of the aluminum phosphate gel is 2-3.

21. The catalyst according to any one of claims 1-12, wherein, The preparation method of the phosphorus aluminum glue includes: mixing an acid-soluble aluminum precursor with water to form a slurry, and then adding a phosphoric acid solution at 45-55℃ to react and obtain the phosphorus aluminum glue; The reaction conditions include a temperature of 75-85℃ and a time of 1-2 hours.

22. The catalyst according to claim 21, wherein, The acid-soluble aluminum precursor is selected from at least one of boehmite, alumina, aluminum hydroxide, aluminum isopropoxide, and aluminum isobutoxide.

23. A method for preparing a catalytic cracking catalyst, the method comprising: (1) The molecular sieve, the second suspension containing clay and the first binder precursor are pulped to obtain the first slurry; (2) The first slurry is mixed with at least a portion of the second binder precursor to obtain a second slurry with a viscosity not greater than 0.1 Pa·s; (3) The second slurry and the third binder precursor are mixed to obtain a third slurry with a viscosity of not less than 1 Pa·s; (4) The third slurry is aged with an amphiphilic block polymer to obtain a fourth slurry; (5) The fourth slurry is spray-dried and then calcined; through 27 Al MAS NMR characterization showed that the ratio of the peak area of ​​the resonance signal at a chemical shift of 45±1 ppm to the peak area of ​​the resonance signal at a chemical shift of 53±1 ppm was no greater than 1.

5. The first binder precursor is selected from at least one of the following: boehmite, hydrated alumina with a monohydrate structure, hydrated alumina with a trihydrate structure, hydrated alumina with a Bayer structure, γ-alumina, η-alumina, θ-alumina and x-alumina. The second binder precursor is aluminum sol; The third binder precursor is aluminum phosphate glue.

24. The method according to claim 23, wherein, The amounts of clay, molecular sieve, and binder precursor used in the prepared catalyst are such that, based on the total mass of the catalyst, the mass content of clay is 5-20%, the mass content of molecular sieve is 60-85%, and the mass content of binder is 10-35%, wherein the binder is the sum of the first binder, the second binder, and the third binder.

25. The method according to claim 24, wherein, The amounts of clay, molecular sieve, and binder precursor used in the prepared catalyst are such that, based on the total mass of the catalyst, the mass content of clay is 5-20%, the mass content of molecular sieve is 60-70%, and the mass content of binder is 16-35%, wherein the binder is the sum of the first binder, the second binder, and the third binder.

26. The method according to claim 23, wherein, The dry basis mass ratio of the second binder precursor to the first binder precursor is 1-4; The dry basis mass ratio of the second binder precursor to the third binder precursor is 0.3-1.

27. The method according to claim 26, wherein, The dry basis mass ratio of the second binder precursor to the first binder precursor is 1.7-4; The dry basis mass ratio of the second binder precursor to the third binder precursor is 0.3-0.

8.

28. The method according to claim 23, wherein, The average crystal size of the molecular sieve is 100-500 nm; The SiO2 / Al2O3 molar ratio of the molecular sieve is 25-200.

29. The method according to claim 28, wherein, The average crystal size of the molecular sieve is 200-300 nm; The SiO2 / Al2O3 molar ratio of the molecular sieve is 25-100.

30. The method according to claim 23, wherein, through 27 Al MAS NMR characterization showed that the ratio of the resonance peak area at a chemical shift of 45±1 ppm to the resonance peak area at a chemical shift of 53±1 ppm was 0.35-1.

5.

31. The method according to claim 23, wherein, The molecular sieve is selected from at least one of ZSM-5 molecular sieve, IM-5 molecular sieve and ZSM-22 molecular sieve.

32. The method according to any one of claims 23-31, wherein, The aluminum-chlorine ratio of the aluminum sol is not higher than 1.

4.

33. The method according to claim 32, wherein, The aluminum sol has an aluminum-chlorine ratio of 1.2-1.

3.

34. The method according to any one of claims 23-31, wherein, The phosphorus aluminum gel has a network structure.

35. The method according to any one of claims 23-31, wherein, The mass ratio of Al2O3 to P2O5 in the phosphorus aluminum gel is 0.25-0.

35.

36. The method according to any one of claims 23-31, wherein, The pH of the phosphate aluminum gel is 1-3.

37. The method of claim 36, wherein, The pH of the aluminum phosphate gel is 2-3.

38. The method according to any one of claims 23-31, wherein, The preparation method of the phosphorus aluminum glue includes: mixing an acid-soluble aluminum precursor with water to form a slurry, and then adding a phosphoric acid solution at 45-55℃ to react and obtain the phosphorus aluminum glue; The reaction conditions include a temperature of 75-85℃ and a time of 1-2 hours.

39. The method according to claim 38, wherein, The acid-soluble aluminum precursor is selected from at least one of boehmite, alumina, aluminum hydroxide, aluminum isopropoxide, and aluminum isobutoxide.

40. The method according to any one of claims 23-31, wherein, The aging conditions described in step (4) include a temperature of 50-85℃ and a time of 0.5-4h.

41. The method according to claim 40, wherein, The aging conditions described in step (4) include: a temperature of 60-80℃ and a time of 1-2h.

42. The method according to any one of claims 23-31, wherein, The mass of the amphiphilic block polymer is 5-30% of the dry basis mass of the third slurry.

43. The method according to claim 42, wherein, The mass of the amphiphilic block polymer is 10-20% of the dry basis mass of the third slurry.

44. The method according to any one of claims 23-31, wherein, The amphiphilic block polymer is selected from at least one of polyethylene glycol-b-polypropylene glycol, polystyrene-b-polyacrylic acid, and polystyrene-b-polyethylene glycol.

45. The use of a catalytic cracking catalyst according to any one of claims 1-22 or a catalytic cracking catalyst prepared by the method according to any one of claims 23-44 in a catalytic cracking reaction.

46. ​​The application according to claim 45, wherein, The catalytic cracking reaction is a naphtha catalytic cracking reaction.

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