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 phosphorus-containing ZSM-5 molecular sieve, a binder, and clay; based on the total mass of the catalyst, the mass content of the phosphorus-containing ZSM-5 molecular sieve is 60-80%, the mass content of clay is 5-20%, and the mass content of the binder is 10-35%; the proportion of strong acid in the catalyst to the total acid content is 50-60%; and the ratio of Brønsted acid (B acid) to Lewis acid (L acid) in the catalyst is 2-8. The catalyst of this invention, when applied to catalytic cracking reactions, especially naphtha catalytic cracking reactions, exhibits 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] CN109012742B discloses a catalyst for naphtha catalytic cracking composed of 65-80 wt% LaZSM-5 molecular sieve and 20-35 wt% Al2O3, with a lanthanum content of 0.3-1.7 wt%. However, this catalyst is used in a multi-stage fixed-bed adiabatic reactor for naphtha catalytic cracking. The fixed-bed adiabatic reactor contains 2-6 catalyst beds and needs to be coupled with methanol, making the application complex and unsuitable for industrial application.

[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 method, and its application. The catalyst described in this invention, when applied to catalytic cracking reactions, especially naphtha catalytic cracking reactions, exhibits 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 phosphorus-containing ZSM-5 molecular sieve, a binder, and clay; based on the total mass of the catalyst, the mass content of the phosphorus-containing ZSM-5 molecular sieve is 60-80%, the mass content of the clay is 5-20%, and the mass content of the binder is 10-35%.

[0009] The strong acid content of the catalyst accounts for 50-60% of the total acid content;

[0010] The ratio of the amount of Brønsted acid to Lønsted acid in the catalyst is 2-8.

[0011] A second aspect of the present invention provides a method for preparing a catalytic cracking catalyst, the method comprising:

[0012] (1) Phosphorus-containing ZSM-5 molecular sieve, clay-containing second suspension and first binder precursor are pulped to obtain 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 0.2 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 spray-dried and then calcined;

[0016] The average grain size of the phosphorus-containing ZSM-5 molecular sieve is 100-500 nm.

[0017] 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.

[0018] The beneficial effects of the present invention through the above technical solution include:

[0019] The catalyst of this invention contains phosphorus-containing ZSM-5 molecular sieve active components, and also possesses high molecular sieve content and suitable acid properties, resulting in excellent catalytic performance. When applied to catalytic cracking reactions, particularly naphtha catalytic cracking, the catalyst exhibits high conversion rates and low-carbon olefin yields, while maintaining a relatively low coke yield. Detailed Implementation

[0020] 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.

[0021] The dry basis mentioned in this invention refers to the product obtained by calcination at 550°C for 2 hours.

[0022] The present invention provides a catalytic cracking catalyst, the catalyst comprising a phosphorus-containing ZSM-5 molecular sieve, a binder, and clay; based on the total mass of the catalyst, the mass content of the phosphorus-containing ZSM-5 molecular sieve is 60-80%, the mass content of the clay is 5-20%, and the mass content of the binder is 10-35%.

[0023] The strong acid content of the catalyst accounts for 50-60% of the total acid content;

[0024] The ratio of the amount of Brønsted acid to Lønsted acid in the catalyst is 2-8.

[0025] Existing catalytic cracking catalysts typically have a high ratio of Brønsted acid (B) to Lewis acid (L) content, generally above 10. While this results in high conversion rates, it also makes it difficult to precisely control product distribution. This invention, however, controls the ratio of B to L in the catalyst to a lower level, which helps to suppress coke formation while ensuring diene selectivity in product distribution.

[0026] To further improve the catalytic performance of the catalyst, preferably, based on the total mass of the catalyst, the mass content of phosphorus-containing ZSM-5 molecular sieve is 60-70%, the mass content of clay is 5-20%, and the mass content of binder is 16-35%.

[0027] The total content of all components in the catalyst of this invention is 100%.

[0028] The content of each component of the catalyst described in this invention is obtained through feeding calculations.

[0029] According to the present invention, preferably, the proportion of strong acid in the catalyst to the total acid content is 55-60%. This preferred embodiment can improve the raw material conversion rate.

[0030] The proportion of strong acid to total acid in the present invention is determined by the NH3-TPD method.

[0031] In this invention, unless otherwise specified, the strong acid refers to the acid center corresponding to the desorption temperature of NH3 greater than 300°C.

[0032] According to the present invention, preferably, the ratio of Brønsted acid (B acid) to Lewis acid (L acid) in the catalyst is 3-8. This preferred embodiment can reduce the formation of coke during the reaction process.

[0033] In this invention, the ratio of the amount of B acid to the amount of L acid is determined by the pyridine adsorption infrared acid method.

[0034] According to the present invention, preferably, the phosphorus content (calculated as P2O5) is 1-12% based on the total mass of the phosphorus-containing ZSM-5 molecular sieve, more preferably 2-9%. This preferred embodiment ensures the stability of the ZSM-5 molecular sieve under high hydrothermal conditions.

[0035] The phosphorus content in the phosphorus-containing ZSM-5 molecular sieve of the present invention was determined by X-ray fluorescence spectroscopy.

[0036] The present invention does not have any particular limitation on the source of the phosphorus-containing ZSM-5 molecular sieve; it can be obtained by conventional methods in the art or by commercial purchase.

[0037] 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.

[0038] According to the present invention, preferably, the adhesive comprises a first adhesive, a second adhesive, and a third adhesive.

[0039] 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.

[0040] 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.

[0041] According to the present invention, preferably, the second binder is obtained by calcining aluminum sol.

[0042] 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.

[0043] The aluminum-chlorine ratio of the aluminum sol described in this invention was determined by X-ray fluorescence spectroscopy.

[0044] 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.

[0045] According to the present invention, preferably, the third binder is obtained by calcining aluminum-phosphorus magnesium phosphate adhesive.

[0046] 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.

[0047] 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.

[0048] According to the present invention, preferably, the mass ratio of the second adhesive to the third adhesive is 0.1-0.9, more preferably 0.2-0.7.

[0049] According to the present invention, preferably, the mass ratio of Al2O3 to P2O5 in the phosphorus aluminum magnesium adhesive is 0.25-0.35, and the mass of MgO is 1-5% of the sum of the masses of Al2O3 and P2O5. This preferred embodiment ensures the adhesive performance of the binder while precisely adjusting the acidic sites provided by the binder, thereby achieving lower coke selectivity.

[0050] The mass ratio of Al2O3 to P2O5 in the phosphorus aluminum magnesium adhesive of the present invention was determined by X-ray fluorescence spectroscopy.

[0051] The mass of MgO in the phosphorus aluminum magnesium adhesive of the present invention is obtained by calculation of the amount of material added.

[0052] The present invention does not impose any particular limitation on the preparation method of the above-mentioned aluminum-phosphorus magnesium colloid, as long as the aluminum-phosphorus magnesium colloid with the above composition 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-phosphorus magnesium colloid.

[0053] According to the present invention, preferably, the preparation method of the aluminum-phosphorus magnesium adhesive includes:

[0054] (a) Acid-soluble aluminum precursor is mixed with water and slurryed, and then phosphoric acid solution is added at 45-55℃ to carry out the first reaction to obtain the phosphoric aluminum gel;

[0055] (b) The phosphorus aluminum glue obtained in step (a) is reacted with magnesium oxide in a second reaction to obtain the phosphorus aluminum magnesium glue.

[0056] In the preparation method of the phosphorus aluminum magnesium adhesive of the present invention, by controlling the addition temperature of phosphoric acid, and preferably controlling the two-step reaction conditions, the composition of the obtained phosphorus aluminum magnesium adhesive meets the above requirements, which is beneficial to the stability of the phosphorus aluminum magnesium adhesive.

[0057] According to the present invention, preferably, the phosphoaluminum colloid obtained in step (a) has a network structure.

[0058] The structure of the aluminum phosphate gel described in this invention was determined by transmission electron microscopy.

[0059] In existing technologies, aluminum phosphate gels generally have a dispersed spherical nanoparticle structure, which suffers from poor adhesion and structural instability. However, during the research process, the inventors discovered that aluminum phosphate gels with a network structure possess both excellent adhesion properties and a stable framework, resulting in aluminum phosphate magnesium gels with excellent adhesion properties, which is beneficial for improving the mechanical strength of catalysts.

[0060] According to the present invention, preferably, the pH of the phosphorus-aluminum colloid obtained in step (a) is 1-3, more preferably 2-3. This preferred embodiment ensures the structure and stability of the phosphorus-aluminum colloid binder, while also ensuring the stability of the molecular sieve structure, further contributing to improved catalyst reactivity and mechanical strength. Furthermore, the obtained phosphorus-aluminum-magnesium colloid, while maintaining the above advantages, can further regulate the overall acidity of the catalyst, thereby achieving lower coke selectivity.

[0061] According to the present invention, preferably, the conditions for the first reaction include: a temperature of 75-85°C and a time of 1-2 hours.

[0062] The present invention does not have a particular limitation on the amount of water used in step (a), as long as the pH of the aluminum phosphate gel is within the above-mentioned range.

[0063] The present invention does not particularly limit the precursor of the acid-soluble aluminum or the phosphoric acid solution, but the mass ratio of Al2O3 to P2O5 in the obtained aluminum-phosphorus magnesium colloid is 0.25-0.35.

[0064] 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.

[0065] According to the present invention, preferably, the conditions for the second reaction include: a temperature of 15-35°C and a time of 8-12 hours.

[0066] According to the present invention, preferably, the mass amount of magnesium oxide is 1-5% of the sum of the masses of Al2O3 and P2O5.

[0067] A second aspect of the present invention provides a method for preparing a catalytic cracking catalyst, the method comprising:

[0068] (1) Phosphorus-containing ZSM-5 molecular sieve, clay-containing second suspension and first binder precursor are pulped to obtain first slurry;

[0069] (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 0.2 Pa·s;

[0070] (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;

[0071] (4) The third slurry is spray-dried and then calcined;

[0072] The average grain size of the phosphorus-containing ZSM-5 molecular sieve is 100-500 nm.

[0073] 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 catalytic cracking catalyst obtained by the method provided in this invention, which uses phosphorus-containing ZSM-5 molecular sieves with a specific average grain size in combination with other substances and through specific steps, overcomes the above-mentioned defects. The resulting catalytic cracking catalyst not only meets the mechanical strength requirements of catalytic cracking reactions but also has a high molecular sieve content and suitable acid properties. When applied to catalytic cracking reactions, especially naphtha catalytic cracking reactions, it exhibits higher reactant conversion rates and ethylene and propylene yields, as well as lower coke yields.

[0074] In this invention, the viscosity of the second slurry is no greater than 0.2 Pa·s, preferably 0.01-0.2 Pa·s, for example, it can be 0.01 Pa·s, 0.02 Pa·s, 0.03 Pa·s, 0.04 Pa·s, 0.05 Pa·s, 0.06 Pa·s, 0.07 Pa·s, 0.08 Pa·s, 0.09 Pa·s, 0.1 Pa·s, 0.11 Pa·s, 0.12 Pa·s, 0.13 Pa·s, 0.14 Pa·s, 0.15 Pa·s, 0.16 Pa·s, 0.17 Pa·s, 0.18 Pa·s, 0.19 Pa·s, 0.2 Pa·s, and any value within any two of these values. This preferred embodiment is advantageous for obtaining a homogeneous catalyst (i.e., a uniform distribution of each component).

[0075] In this invention, the viscosity of the third slurry is not less than 1 Pa·s, preferably 1-3 Pa·s, for example, it can be 1 Pa·s, 1.1 Pa·s, 1.2 Pa·s, 1.3 Pa·s, 1.4 Pa·s, 1.5 Pa·s, 1.6 Pa·s, 1.7 Pa·s, 1.8 Pa·s, 1.9 Pa·s, 2 Pa·s, 2.1 Pa·s, 2.2 Pa·s, 2.3 Pa·s, 2.4 Pa·s, 2.5 Pa·s, 2.6 Pa·s, 2.7 Pa·s, 2.8 Pa·s, 2.9 Pa·s, 3 Pa·s, and any value within any two of these values. This preferred embodiment is beneficial for improving the mechanical strength of the catalyst.

[0076] The viscosity described in this invention is measured using a viscometer.

[0077] 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.

[0078] According to the present invention, preferably, the amounts of clay, phosphorus-containing ZSM-5 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 phosphorus-containing ZSM-5 molecular sieve is 60-80%, 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.

[0079] More preferably, the amounts of clay, phosphorus-containing ZSM-5 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 phosphorus-containing ZSM-5 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.

[0080] 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.

[0081] According to the present invention, preferably, the dry basis mass ratio of the second binder precursor to the third binder precursor is 0.1-0.9, more preferably 0.2-0.7.

[0082] According to the present invention, preferably, the average grain size of the phosphorus-containing ZSM-5 molecular sieve is 200-300 nm. This preferred embodiment increases the probability of contact between the reactants and the catalytically active sites, thereby improving the catalyst's reactivity.

[0083] 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.

[0084] 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.

[0085] According to the present invention, preferably, the SiO2 / Al2O3 molar ratio of the phosphorus-containing ZSM-5 molecular sieve is 20-200, more preferably 25-100, for example, it can be 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, and any value within any range formed by any two of these values. This preferred embodiment is beneficial for improving the catalytic activity of the catalyst. When the SiO2 / Al2O3 molar ratio of the phosphorus-containing ZSM-5 molecular sieve is higher than this range, the number of active sites on the catalyst decreases, and the catalytic activity of the catalyst is significantly reduced.

[0086] According to the present invention, preferably, the phosphorus content, calculated as P2O5, is 1-12% based on the total mass of the phosphorus-containing ZSM-5 molecular sieve, and more preferably 2-9%.

[0087] The present invention does not have any particular limitation on the source of the phosphorus-containing ZSM-5 molecular sieve; it can be obtained by conventional methods in the art or by commercial purchase.

[0088] 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.

[0089] 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.

[0090] According to the present invention, preferably, the second binder precursor is aluminum sol.

[0091] 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.

[0092] 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.

[0093] According to the present invention, preferably, the third binder precursor is a phosphorus aluminum magnesium adhesive.

[0094] According to the present invention, preferably, the mass ratio of Al2O3 to P2O5 in the phosphorus aluminum magnesium glue is 0.25-0.35, and the mass of MgO is 1-5% of the sum of the masses of Al2O3 and P2O5.

[0095] According to the present invention, preferably, the preparation method of the aluminum-phosphorus magnesium adhesive includes:

[0096] (a) Acid-soluble aluminum precursor is mixed with water and slurryed, and then phosphoric acid solution is added at 45-55℃ to carry out the first reaction to obtain the phosphoric aluminum gel;

[0097] (b) The phosphorus aluminum glue obtained in step (a) is reacted with magnesium oxide in a second reaction to obtain the phosphorus aluminum magnesium glue.

[0098] According to the present invention, preferably, the phosphoaluminum colloid obtained in step (a) has a network structure.

[0099] According to the present invention, preferably, the pH of the aluminum phosphate gel obtained in step (a) is 1-3, more preferably 2-3.

[0100] According to the present invention, preferably, the conditions for the first reaction include: a temperature of 75-85°C and a time of 1-2 hours.

[0101] The present invention does not particularly limit the precursor of the acid-soluble aluminum or the phosphoric acid solution, but the mass ratio of Al2O3 to P2O5 in the obtained aluminum-phosphorus magnesium colloid is 0.25-0.35.

[0102] The present invention does not have a particular limitation on the amount of water used in step (a), as long as the pH of the aluminum phosphate gel is within the above-mentioned range.

[0103] 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.

[0104] According to the present invention, preferably, the conditions for the second reaction include: a temperature of 15-35°C and a time of 8-12 hours.

[0105] According to the present invention, preferably, the mass amount of magnesium oxide is 1-5% of the sum of the masses of Al2O3 and P2O5.

[0106] The present invention does not impose any particular limitation on the order of adding the phosphorus-containing ZSM-5 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.

[0107] Preferably, the phosphorus-containing ZSM-5 molecular sieve is provided in the form of a first suspension.

[0108] 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.

[0109] 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%.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] According to a preferred embodiment of the present invention, the second liquid medium is of the same type as the first liquid medium.

[0114] 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 28-40 wt%.

[0115] Preferably, the first binder precursor is provided in the form of a third suspension.

[0116] 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.

[0117] 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.

[0118] Preferably, the weight ratio of the acid to the first binder precursor on a dry basis is 0.1-1:1.

[0119] 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.

[0120] According to a preferred embodiment of the present invention, the third liquid medium is of the same type as the first liquid medium.

[0121] 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%.

[0122] The present invention does not impose any particular limitation on the specific conditions of spray drying in step (4), and can refer to conventional methods in the art. The present invention does not impose any limitation here.

[0123] The present invention does not particularly limit the roasting conditions in step (4), and can refer to conventional methods in the art. Preferably, the roasting conditions in step (4) 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.

[0124] 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.

[0125] 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.

[0126] Preferably, the application process includes: contacting the feedstock oil with the catalytic cracking catalyst.

[0127] The present invention does not impose 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. Preferably, the conditions for the contact reaction include a temperature of 580-650°C.

[0128] Preferably, the mass ratio of catalyst to feedstock oil is 3-10.

[0129] The present invention allows for a wide range of choices of the type of raw material oil. Preferably, the raw material oil is naphtha.

[0130] 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.

[0131] 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.

[0132] Preferably, the hydrothermal aging is carried out under conditions of 100% water vapor.

[0133] The present invention will be described in detail below through embodiments.

[0134] 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;

[0135] Boehmite is a commercially available product from Shandong Aluminum Plant, with a solid content of 66.9% by weight.

[0136] Kaolin is a commercially available product of Suzhou Kaolin Company, with a dry basis weight of 84.6%.

[0137] Preparation Examples 1-3 illustrate the preparation of the phosphorus aluminum magnesium adhesive described in this invention.

[0138] Preparation Example 1

[0139] (a) Weigh 1.1 kg of boehmite and 2.9 kg of deionized water and mix them evenly. Then heat the mixture to 50°C, add 4 kg of phosphoric acid (85 wt%), and heat to 80°C for 90 min to prepare aluminum phosphate gel. The aluminum phosphate gel has a network structure and a pH of 2.

[0140] (b) Weigh 0.16 kg of solid magnesium oxide (product of Sinopec Catalyst Company Qilu Branch, solid content 98.5%) and add it to the above-mentioned aluminum phosphate gel. React at room temperature for 12 hours to prepare aluminum phosphate magnesium gel. The mass ratio of Al2O3 to P2O5 in the aluminum phosphate magnesium gel is 0.3, and the mass of MgO is 5% of the sum of the masses of Al2O3 and P2O5.

[0141] Preparation Example 2

[0142] (a) Weigh 1.18 kg of boehmite and 2.82 kg of deionized water and mix them evenly. Then heat the mixture to 45°C, add 4 kg of phosphoric acid (85 wt%), and heat to 80°C for 60 min to prepare aluminum phosphate gel. The aluminum phosphate gel has a network structure and a pH of 2.2.

[0143] (b) Weigh 0.1 kg of solid magnesium oxide (product of Sinopec Catalyst Company Qilu Branch, solid content 98.5%) and add it to the above phosphorus aluminum glue. React at room temperature for 8 hours to prepare phosphorus aluminum magnesium glue.

[0144] The mass ratio of Al2O3 to P2O5 in the phosphorus aluminum magnesium glue is 0.32, and the mass of MgO is 3% of the sum of the masses of Al2O3 and P2O5.

[0145] Preparation Example 3

[0146] (a) Weigh 0.83 kg of boehmite and 2.18 kg of deionized water and mix them evenly. Then heat the mixture to 55°C, add 3 kg of phosphoric acid (85 wt%), heat to 75°C, and react for 60 min to prepare aluminum phosphate gel. The aluminum phosphate gel has a network structure and a pH of 2.5.

[0147] (b) Weigh 0.02 kg of solid magnesium oxide (product of Sinopec Catalyst Company Qilu Branch, solid content 98.5%) and add it to the above phosphorus aluminum glue. React at room temperature for 8 hours to prepare phosphorus aluminum magnesium glue.

[0148] The mass ratio of Al2O3 to P2O5 in the phosphorus aluminum magnesium glue is 0.3, and the mass of MgO is 1% of the sum of the masses of Al2O3 and P2O5.

[0149] Example 1

[0150] The preparation method of phosphorus-containing ZSM-5 molecular sieve includes: dissolving diammonium hydrogen phosphate in 6.65 kg of deionized water to obtain an aqueous solution of diammonium hydrogen phosphate; impregnating the ZSM-5 molecular sieve with the diammonium hydrogen phosphate aqueous solution; drying at 120℃; and calcining at 550℃ for 2 h to obtain phosphorus-containing ZSM-5 molecular sieve with a dry basis weight of 97%.

[0151] A phosphorus-containing ZSM-5 molecular sieve suspension with a solid content of 33 wt% was prepared by weighing 6.65 kg of phosphorus-containing ZSM-5 molecular sieve and mixing it with deionized water. A kaolin suspension with a solid content of 38 wt% was prepared by weighing 0.85 kg of kaolin, 0.33 kg of alumina sol, and deionized water. A boehmite suspension with a solid content of 17 wt% was prepared by weighing 0.32 kg of boehmite and deionized water and mixing them evenly, 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 a first slurry. 1.67 kg of alumina sol was added to the first slurry and stirred for 5 min to obtain a second slurry. 5.2 kg of phosphorus-aluminum-magnesium phosphate glue prepared in Preparation Example 1 was added to the second slurry and stirred for 5 min to obtain a third slurry. The third slurry was spray-dried and then calcined at 550°C for 2 hours to obtain catalyst A. Some conditions during the preparation of catalyst A are shown in Table 1. The composition and characteristic parameters of catalyst A are shown in Table 2.

[0152] Example 2

[0153] The preparation method of phosphorus-containing ZSM-5 molecular sieve includes: dissolving diammonium hydrogen phosphate in 12.26 kg of deionized water to obtain an aqueous solution of diammonium hydrogen phosphate; impregnating the ZSM-5 molecular sieve with the diammonium hydrogen phosphate aqueous solution; drying at 120℃; and calcining at 550℃ for 2 h to obtain phosphorus-containing ZSM-5 molecular sieve with a dry basis weight of 97%.

[0154] A phosphorus-containing ZSM-5 molecular sieve suspension with a solid content of 36 wt% was prepared by weighing 12.26 kg of phosphorus-containing ZSM-5 molecular sieve and mixing it with deionized water. A kaolin suspension with a solid content of 38 wt% was prepared by weighing 2.54 kg of kaolin, 1.4 kg of alumina sol, and deionized water and mixing them evenly. A boehmite suspension with a solid content of 21 wt% was prepared by adding 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 and stirred for 15 min to obtain a first slurry. 4.18 kg of alumina sol was added to the first slurry and stirred for 5 min to obtain a second slurry. 9.67 kg of phosphorus-aluminum-magnesium colloid prepared in Preparation Example 2 was added to the second slurry and stirred for 5 min to obtain a third slurry. The third slurry was spray-dried and then calcined at 550°C for 2 hours to obtain catalyst B. Some conditions during the preparation of catalyst B are shown in Table 1. The composition and characteristic parameters of catalyst B are shown in Table 2.

[0155] Example 3

[0156] The preparation method of phosphorus-containing ZSM-5 molecular sieve includes: dissolving diammonium hydrogen phosphate in 10.74 kg of deionized water to obtain an aqueous solution of diammonium hydrogen phosphate; impregnating the ZSM-5 molecular sieve with the diammonium hydrogen phosphate aqueous solution; drying at 120℃; and calcining at 550℃ for 2 h to obtain phosphorus-containing ZSM-5 molecular sieve with a dry basis weight of 97%.

[0157] A phosphorus-containing ZSM-5 molecular sieve suspension with a solid content of 31 wt% was prepared by weighing 10.74 kg of phosphorus-containing ZSM-5 molecular sieve and mixing it with deionized water. A kaolin suspension with a solid content of 30 wt% was prepared by weighing 2.12 kg of kaolin, 0.5 kg of alumina sol, and deionized water and mixing them evenly. A boehmite suspension with a solid content of 20 wt% was prepared by adding concentrated hydrochloric acid (the weight ratio of the acid to the first binder precursor on a dry basis was 0.1). The kaolin suspension, boehmite suspension, and phosphorus-containing ZSM-5 molecular sieve suspension were then mixed and stirred for 15 min to obtain a first slurry. 3.14 kg of alumina sol was added to the first slurry and stirred for 5 min to obtain a second slurry. 3.9 kg of phosphorus-aluminum-magnesium colloid prepared in Preparation Example 3 was added to the second slurry and stirred for 5 min to obtain a third slurry. The third slurry was spray-dried and then calcined at 550°C for 2 hours to obtain the catalyst, denoted as C. Some conditions during the preparation of catalyst C are shown in Table 1. The composition and characteristic parameters of catalyst C are shown in Table 2.

[0158] Example 4

[0159] The process was carried out according to Example 1, except that the average crystallite size of the phosphorus-containing ZSM-5 molecular sieve was 450 nm, resulting in a catalyst denoted as D. Some conditions during the preparation of catalyst D are shown in Table 1. The composition and characteristic parameters of catalyst D are shown in Table 2.

[0160] Comparative Example 1

[0161] The process was carried out according to Example 1, except that magnesium aluminum phosphate gel was not added, resulting in a catalyst denoted as E. Some conditions during the preparation of catalyst E are shown in Table 1. The composition and characteristic parameters of catalyst E are shown in Table 2.

[0162] Comparative Example 2

[0163] The preparation method of phosphorus-containing ZSM-5 molecular sieve includes: dissolving diammonium hydrogen phosphate in 4.09 kg of deionized water to obtain an aqueous solution of diammonium hydrogen phosphate; impregnating the ZSM-5 molecular sieve with the diammonium hydrogen phosphate aqueous solution; drying at 120℃; and calcining at 550℃ for 2 h to obtain phosphorus-containing ZSM-5 molecular sieve with a dry basis weight of 97%.

[0164] 4.09 kg of phosphorus-containing ZSM-5 molecular sieve and deionized water were weighed and homogenized to prepare a phosphorus-containing ZSM-5 molecular sieve suspension with a solid content of 30 wt%. 2.96 kg of kaolin and deionized water were weighed and homogenized to prepare a kaolin suspension with a solid content of 32 wt%. 1.49 kg of boehmite and deionized water were weighed and homogenized, and then hydrochloric acid was added (the weight ratio of the acid to the first binder precursor on a dry basis was 0.12) to prepare a boehmite suspension with a solid content of 18 wt%. The above kaolin suspension, boehmite suspension, and molecular sieve suspension were homogenized for 15 min to obtain a first slurry. 5.5 kg of phosphorus aluminum magnesium colloid prepared in Preparation Example 1 was added to the first slurry and homogenized for 5 min to obtain a second slurry. The second slurry was spray-dried and then calcined at 550℃ for 2 hours to obtain catalyst F. Some conditions in the preparation process of catalyst F are shown in Table 1. The composition and characteristic parameters of catalyst F are shown in Table 2.

[0165] Comparative Example 3

[0166] The method of Example 1 was followed, except that the phosphorus aluminum magnesium glue obtained in Preparation Example 1 was not added to the third slurry; instead, phosphorus aluminum glue obtained in Preparation Example 1 was added, so that the mass ratio of the second binder to the third binder remained at 0.2, resulting in a catalyst, denoted as G. Some conditions in the preparation process of catalyst G are shown in Table 1. The composition and characteristic parameters of catalyst G are shown in Table 2.

[0167] Comparative Example 4

[0168] The process was carried out according to Example 1, except that 5.07 kg of the aluminum phosphate gel prepared in Preparation Example 1 was added to the second slurry and stirred for 5 minutes to obtain the third slurry. 0.1 kg of magnesium oxide (product of Sinopec Catalyst Company Qilu Branch, solid content 98.5%) was added to the third slurry, followed by spray drying and calcination at 550°C for 2 hours to obtain the catalyst, denoted as H. Catalyst H contains 65 wt% molecular sieve, 27 wt% binder, 7 wt% clay, and 1 wt% MgO.

[0169] Some conditions in the preparation process of catalyst H are shown in Table 1. The composition and characteristic parameters of catalyst H are shown in Table 2.

[0170] Table 1

[0171]

[0172] Note: Phosphorus content refers to the phosphorus content calculated as P2O5 based on the total mass of phosphorus-containing ZSM-5 molecular sieves.

[0173] Table 2

[0174]

[0175]

[0176] Test Example 1

[0177] The catalysts 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 9g, 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.

[0178] Table 3

[0179]

[0180] Table 4

[0181]

[0182] As shown in Table 4, applying the catalyst described in this invention to the catalytic cracking reaction of naphtha results in higher reactant conversion rates, higher ethylene and propylene yields, and lower coke yields. Table 4 also demonstrates that the catalyst described in this invention exhibits good hydrothermal stability.

[0183] 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 phosphorus-containing ZSM-5 molecular sieve, binder, and clay; based on the total mass of the catalyst, the mass content of phosphorus-containing ZSM-5 molecular sieve is 60-80%, the mass content of clay is 5-20%, and the mass content of binder is 10-35%. In the catalyst, the proportion of strong acids with an NH3 desorption temperature greater than 300℃ to the total acid content is 50-60%. The ratio of the amount of Brønsted acid to Lønsted acid in the catalyst is 2-8. 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 magnesium glue; The preparation method of the catalytic cracking catalyst includes: (1) The phosphorus-containing ZSM-5 molecular sieve, the clay-containing second suspension 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 0.2 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 spray-dried and then calcined; The average grain size of the phosphorus-containing ZSM-5 molecular sieve is 100-500 nm.

2. The catalyst according to claim 1, wherein, Based on the total mass of the catalyst, the mass content of phosphorus-containing ZSM-5 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, In the catalyst, the proportion of strong acids with an NH3 desorption temperature greater than 300℃ to the total acid content is 55-60%.

4. The catalyst according to claim 1, wherein, The ratio of Brønsted acid to Lewis acid in the catalyst is 3-8.

5. The catalyst according to claim 1, wherein, Based on the total mass of phosphorus-containing ZSM-5 molecular sieves, the phosphorus content, calculated as P2O5, is 1-12%.

6. The catalyst according to claim 5, wherein, Based on the total mass of phosphorus-containing ZSM-5 molecular sieves, the phosphorus content, calculated as P2O5, is 2-9%.

7. The catalyst according to any one of claims 1-6, wherein, The aluminum-chlorine ratio of the aluminum sol is not higher than 1.

4.

8. The catalyst according to claim 7, wherein, The aluminum sol has an aluminum-chlorine ratio of 1.2-1.

3.

9. The catalyst according to any one of claims 1-6, 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 0.1-0.

9.

10. The catalyst according to claim 9, wherein, The mass ratio of the second adhesive to the first adhesive is 1.7-4; The mass ratio of the second adhesive to the third adhesive is 0.2-0.

7.

11. The catalyst according to any one of claims 1-6, wherein, The mass ratio of Al2O3 to P2O5 in the phosphorus aluminum magnesium glue is 0.25-0.35, and the mass of MgO is 1-5% of the sum of the masses of Al2O3 and P2O5.

12. The catalyst according to any one of claims 1-6, wherein, The preparation method of the phosphorus aluminum magnesium adhesive includes: (a) Acid-soluble aluminum precursor is mixed with water and slurryed, and then phosphoric acid solution is added at 45-55°C to carry out the first reaction to obtain the phosphoric aluminum gel; (b) The phosphorus aluminum glue obtained in step (a) is reacted with magnesium oxide in a second reaction to obtain the phosphorus aluminum magnesium glue.

13. The catalyst according to claim 12, wherein, The phosphorus aluminum gel obtained in step (a) has a network structure.

14. The catalyst according to claim 12, wherein, The pH of the aluminum phosphate gel obtained in step (a) is 1-3.

15. The catalyst according to claim 14, wherein, The pH of the aluminum phosphate gel obtained in step (a) is 2-3.

16. The catalyst according to claim 12, wherein, The conditions for the first reaction include: a temperature of 75-85℃ and a time of 1-2 hours; The conditions for the second reaction include a temperature of 15-35℃ and a time of 8-12 hours.

17. A method for preparing a catalytic cracking catalyst, the method comprising: (1) The phosphorus-containing ZSM-5 molecular sieve, the clay-containing second suspension 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 0.2 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 spray-dried and then calcined; The average grain size of the phosphorus-containing ZSM-5 molecular sieve is 100-500 nm. 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 phosphate aluminum magnesium adhesive.

18. The method according to claim 17, wherein, The amounts of clay, phosphorus-containing ZSM-5 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 phosphorus-containing ZSM-5 molecular sieve is 60-80%, 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.

19. The method according to claim 18, wherein, The amounts of clay, phosphorus-containing ZSM-5 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 phosphorus-containing ZSM-5 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.

20. The method of claim 17, 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 0.1-0.

9.

21. The method according to claim 20, 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 0.2-0.

7.

22. The method according to claim 17, wherein, The average grain size of the phosphorus-containing ZSM-5 molecular sieve is 200-300 nm.

23. The method according to claim 17, wherein, The SiO2 / Al2O3 molar ratio of the phosphorus-containing ZSM-5 molecular sieve is 20-200.

24. The method according to claim 23, wherein, The SiO2 / Al2O3 molar ratio of the phosphorus-containing ZSM-5 molecular sieve is 25-100.

25. The method according to claim 17, wherein, Based on the total mass of phosphorus-containing ZSM-5 molecular sieves, the phosphorus content, calculated as P2O5, is 1-12%.

26. The method of claim 25, wherein, Based on the total mass of phosphorus-containing ZSM-5 molecular sieves, the phosphorus content, calculated as P2O5, is 2-9%.

27. The method according to any one of claims 17-26, wherein, The aluminum-chlorine ratio of the aluminum sol is not higher than 1.

4.

28. The method according to claim 27, wherein, The aluminum sol has an aluminum-chlorine ratio of 1.2-1.

3.

29. The method according to any one of claims 17-26, wherein, The mass ratio of Al2O3 to P2O5 in the phosphorus aluminum magnesium glue is 0.25-0.35, and the mass of MgO is 1-5% of the sum of the masses of Al2O3 and P2O5.

30. The method according to any one of claims 17-26, wherein, The preparation method of the phosphorus aluminum magnesium adhesive includes: (a) Acid-soluble aluminum precursor is mixed with water and slurryed, and then phosphoric acid solution is added at 45-55°C to carry out the first reaction to obtain the phosphoric aluminum gel; (b) The phosphorus aluminum glue obtained in step (a) is reacted with magnesium oxide in a second reaction to obtain the phosphorus aluminum magnesium glue.

31. The method according to claim 30, wherein, The phosphorus aluminum gel obtained in step (a) has a network structure.

32. The method according to claim 30, wherein, The pH of the aluminum phosphate gel obtained in step (a) is 1-3.

33. The method according to claim 32, wherein, The pH of the aluminum phosphate gel obtained in step (a) is 2-3.

34. The method according to claim 30, wherein, The conditions for the first reaction include: a temperature of 75-85℃ and a time of 1-2 hours; The conditions for the second reaction include a temperature of 15-35℃ and a time of 8-12 hours.

35. The use of a catalytic cracking catalyst according to any one of claims 1-16 or a catalytic cracking catalyst prepared by any one of claims 17-34 in a catalytic cracking reaction.

36. The application according to claim 35, wherein, The catalytic cracking reaction is a naphtha catalytic cracking reaction.

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