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 resulting catalyst exhibits a straight tube wear index of no more than 3% / h and a thermal wear index of no more than 7% / (5h). The catalyst of this invention possesses the advantages of both high mechanical strength and a high proportion of molecular sieve.

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] CN1048428C discloses a catalyst for the conversion of petroleum hydrocarbons to produce low-carbon olefins, which is composed of 0-70% by weight clay, 5-90% by weight inorganic oxides and 10-35% by weight zeolite.

[0004] CN1160436C discloses a method for preparing a hydrocarbon cracking catalyst, which includes mixing molecular sieve slurry, boehmite, clay and inorganic acid evenly, adding or not adding aluminum sol to prepare a catalyst slurry, and then spray drying. The composition of the catalyst slurry, on a dry basis by weight, is that the molecular sieve accounts for 15-50%.

[0005] CN1119390C discloses a method for preparing a cracking catalyst, characterized in that molecular sieves and / or alumina sol are added before clay and inorganic acid, and inorganic acid is added after alumina sol, preferably after alumina sol and boehmite. The order of addition of other materials is not particularly restricted, and the catalyst slurry contains a viscosity reducer; wherein the viscosity reducer is ammonium phosphate, diammonium hydrogen phosphate, or ammonium dihydrogen phosphate, or a mixture thereof, and the amount of viscosity reducer added is 0.1-2% of the dry weight of the catalyst.

[0006] CN1272406C discloses a petroleum hydrocarbon cracking catalyst that produces more low-carbon olefins, which has the following composition based on the weight of the catalyst: 0-70% clay, 5-90% inorganic oxides and 10-35% zeolite.

[0007] It can be observed that the above-mentioned catalyst preparation methods are basically applicable to catalysts with a low or medium proportion of molecular sieves. In particular, the molecular sieve content in catalyst preparation methods aimed at increasing the production of low-carbon olefins is less than 50%. To improve the reactivity of the catalyst in the catalytic cracking of naphtha to produce low-carbon olefins, it is necessary to further increase the proportion of molecular sieve components in the catalyst. However, with the increase of molecular sieve components, the proportion of components with high binding properties in the catalyst will inevitably decrease, making it difficult to simultaneously maintain the mechanical strength of the catalyst. Under harsh reaction conditions, a significant catalyst runoff phenomenon will occur. Therefore, new catalyst preparation methods are needed to balance high mechanical strength and a high molecular sieve content in the catalyst. Summary of the Invention

[0008] 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 of this invention possesses the advantages of both high mechanical strength and a high proportion of molecular sieves.

[0009] To achieve the above objectives, the present invention provides a catalytic cracking catalyst, wherein the catalyst comprises a molecular sieve, a binder, and clay;

[0010] Based on the total mass of the catalyst, the mass content of molecular sieve is 60-85%, the mass content of clay is 5-20%, and the mass content of binder is 10-35%.

[0011] The obtained catalyst exhibits a straight tube wear index of no more than 3% / h and a thermal wear index of no more than 7% / (5h). A second aspect of this 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 mixed with a water-absorbing agent to obtain a fourth slurry with a solid content of 40-50 wt%.

[0016] (5) The fourth slurry is spray-dried and then roasted.

[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 provided by this invention has a high molecular sieve content, which significantly improves its catalytic performance. When applied to catalytic cracking reactions, especially naphtha catalytic cracking reactions, the catalyst exhibits higher reactant conversion rates and higher ethylene and propylene yields.

[0020] Meanwhile, the catalyst provided by this invention has high mechanical strength, which is beneficial to enhancing the fluidization performance and wear resistance of the catalyst, thereby increasing the catalyst life and enabling long-term operation. Detailed Implementation

[0021] 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.

[0022] The dry basis mentioned in this invention refers to the product obtained by calcination at 550°C for 2 hours.

[0023] In one aspect, the present invention provides a catalytic cracking catalyst, the catalyst comprising a molecular sieve, a binder, and clay;

[0024] Based on the total mass of the catalyst, the mass content of molecular sieve is 60-85%, the mass content of clay is 5-20%, and the mass content of binder is 10-35%.

[0025] The straight tube wear index of the obtained catalyst is no greater than 3% / h, and the thermal wear index is no greater than 7% / (5h).

[0026] The content of each component in the catalyst described in this invention is calculated by the feed ratio.

[0027] According to the present invention, preferably, the straight tube wear index of the obtained catalyst is 0.5-3% / h, and the thermal wear index is 2.5-7% / (5h).

[0028] The catalyst described in this invention exhibits low straight tube wear index and thermal wear index, indicating that the catalyst can maintain superior mechanical strength and low catalyst consumption even under operating conditions with high catalyst-to-oil ratio, high temperature, and high water vapor content.

[0029] The method for determining the straight pipe wear index described in this invention refers to standard NB / SH / T0964-2017.

[0030] The method for determining the thermal wear index described in this invention is as follows:

[0031] (1) Sample preparation: Pour the sample into an evaporating dish and place it in a muffle furnace at 650℃ for 1 hour. Remove it and cool it in the air for 5 minutes. Place it in a desiccator and weigh 50g ± 0.01g of the sample after 30 minutes. Place it in the desiccator for later use.

[0032] (2) Prepare two filter paper tubes to collect the fine powder precipitated in the first hour and the fine powder precipitated in the following four hours, respectively. Turn on the gas source of the device and adjust the pressure regulating valve to adjust the partial pressure range of the gas source to 0.28MPa~0.32MPa. Install the filter paper tubes at the fine powder collection port of the settler, set the through-hole gas velocity of the wear tube nozzle to 200m / s, and pass a humidified gas flow through at room temperature. Humidify each filter paper tube for 15 minutes, remove the filter paper tubes and weigh them immediately, and record them as wt1 and wt2.

[0033] (3) Load 50g of sample into the abrasion tube, connect the abrasion tube to the settler, and connect the filter paper tube for collecting the fine powder in the first hour to the end of the glass bend. Set the furnace temperature to 700℃ and the gas velocity to 1L / min. Pour gas into the system and wait for the furnace temperature to rise from room temperature to 700℃ at a flow rate of 1L / min.

[0034] (4) After the furnace temperature reaches 700℃, the gas velocity is set to 650m / s through the nozzle orifice, and the wear test under hot conditions begins. During the first hour, the settling tank needs to be fully tapped every half hour. After the first hour, the gas intake is stopped, the filter paper tube is quickly removed, weighed, and recorded as wt3. The filter paper tube used to collect fine powder from the next four hours is then connected to the end of the settling tank, and the wear test under hot conditions continues. During this process, the settling tank is fully tapped every hour. After four hours, the filter paper tube is quickly removed, weighed, and recorded as wt4. Then the gas is stopped, and the experiment ends.

[0035] The thermal abrasion index (HAT) is calculated as follows:

[0036] HAT=((wt4-wt2)+(wt3-wt1)) / 50×100%.

[0037] wt1 — The mass of the empty paper tube containing the fine powder collected in the first hour after humidification, in grams (g);

[0038] wt3 – The total mass of the empty paper tube used for collecting fine powder in the first hour after humidification, and the total mass of fine powder collected in the first hour, expressed in grams (g).

[0039] wt2 – The mass of the empty paper tube containing the fine powder collected after four hours of humidification, in grams (g);

[0040] wt4 – The total mass of the empty paper tube containing fine powder collected after four hours of humidification, plus the total mass of fine powder collected after the four hours of humidification, expressed in grams (g).

[0041] According to the present invention, preferably, the adhesive comprises a first adhesive, a second adhesive, and a third adhesive.

[0042] 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.

[0043] 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.

[0044] According to the present invention, preferably, the second binder is obtained by calcining aluminum sol.

[0045] According to the present invention, preferably, the third binder is obtained by calcining aluminum phosphate glue.

[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 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.

[0048] The aluminum chloride-to-chlorine ratio of the aluminum sol described in this invention was determined by X-ray fluorescence spectroscopy.

[0049] 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.

[0050] According to the present invention, preferably, the phosphorus aluminum gel has a network structure.

[0051] The structure of the aluminum phosphate gel described in this invention was determined by transmission electron microscopy.

[0052] In existing technologies, aluminum phosphate adhesives generally have a dispersed spherical nanoparticle structure, which suffers from poor adhesion and structural instability. However, the inventors of this invention discovered during their research that aluminum phosphate adhesives with a network structure possess both excellent adhesion properties and a stable framework, which is beneficial for improving the mechanical strength of the catalyst.

[0053] 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 is advantageous for obtaining an aluminum phosphate gel colloid with a rich network structure.

[0054] The mass ratio of Al2O3 to P2O5 in the aluminum phosphate gel of the present invention was determined by X-ray fluorescence spectroscopy.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] According to the present invention, preferably, the reaction conditions include: a temperature of 75-85°C and a time of 1-2 hours.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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 60-75%, the mass content of clay is 5-20%, and the mass content of binder is 16-35%.

[0064] More preferably, based on the total mass of the catalyst, the mass content of molecular sieve is 60-70%, the mass content of clay is 5-15%, and the mass content of binder is 18-30%.

[0065] According to the present invention, preferably, the mass ratio of the second binder to the first binder is 1-4, more preferably 1.7-4. This preferred embodiment ensures that the catalyst has good mechanical strength.

[0066] According to the present invention, preferably, the mass ratio of the second binder to the third binder is 0.3-1, more preferably 0.3-0.8. This preferred embodiment can improve the hydrothermal stability and mechanical strength of the catalyst.

[0067] The present invention allows for a wide range of selections of molecular sieves, which can be conventional choices in the field. Preferably, the molecular sieve is selected from at least one of ZSM-5 molecular sieve, IM-5 molecular sieve, and ZSM-22 molecular sieve.

[0068] 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.

[0069] A second aspect of the present invention provides a method for preparing a catalytic cracking catalyst, the method comprising:

[0070] (1) The molecular sieve, the second suspension containing clay and the first binder precursor are pulped to obtain the first slurry;

[0071] (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;

[0072] (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;

[0073] (4) The third slurry is mixed with a water-absorbing agent to obtain a fourth slurry with a solid content of 40-50 wt%.

[0074] (5) The fourth slurry is spray-dried and then roasted.

[0075] In existing technologies, the molecular sieve content of spray-formed catalysts is relatively low, generally not exceeding 40 wt%. This is mainly because to ensure good mechanical strength of the catalyst, the wear index must be maintained at a level of 3.5-7% / h to meet the requirements of catalytic cracking reactions. When the molecular sieve content is too high, spray forming becomes more difficult, and the catalyst wear index exceeds 10% / h, resulting in poor catalyst stability, short lifespan, and inability to achieve long-term operation. The catalyst obtained by the method provided in this invention overcomes the above-mentioned defects, achieving a balance between high mechanical strength and high molecular sieve content. It is suitable for application in catalytic cracking reactions, especially in naphtha catalytic cracking reactions, exhibiting higher reactant conversion rates and higher ethylene and propylene yields.

[0076] 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).

[0077] 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.

[0078] The viscosity described in this invention is measured using a viscometer.

[0079] The solid content of the fourth slurry in this invention is 40-50 wt%, for example, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, and any value within any range formed by any two of these values. This preferred embodiment allows the prepared catalyst to achieve both high mechanical strength and a high proportion of molecular sieves. When the solid content of the fourth slurry is below the above range, the mechanical strength of the catalyst microspheres is poor; when the solid content of the fourth slurry is above the above range, the catalyst slurry is prone to rapid solidification, resulting in poor fluidity, which is detrimental to subsequent spray drying.

[0080] 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.

[0081] 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%, preferably 5-15%; the mass content of molecular sieve is 60-85%, preferably 60-70%; and the mass content of binder is 10-35%, preferably 18-30%; wherein the binder is the sum of the first binder, the second binder, and the third binder.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] According to the present invention, preferably, the second binder precursor is aluminum sol.

[0086] 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.

[0087] 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.

[0088] According to the present invention, preferably, the third binder precursor is aluminum phosphate adhesive.

[0089] According to the present invention, preferably, the phosphorus aluminum gel has a network structure.

[0090] According to the present invention, preferably, the mass ratio of Al2O3 to P2O5 in the phosphorus aluminum gel is 0.25-0.35.

[0091] According to the present invention, preferably, the pH of the aluminum phosphate gel is 1-3, more preferably 2-3, for example 1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, and any value within the range formed by any two of these values.

[0092] 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.

[0093] 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.

[0094] According to the present invention, preferably, the reaction conditions include: a temperature of 75-85°C and a time of 1-2 hours.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] According to the present invention, preferably, the average particle size of the molecular sieve in step (1) is 0.5-2 micrometers, more preferably 0.5-1 micrometer. This preferred embodiment is beneficial for improving the catalytic performance of the catalyst, and also for improving the mechanical strength of the catalyst.

[0101] The method for measuring the average particle size of the molecular sieve in step (1) of this invention is as follows: the laser particle size analyzer method is used, specifically refer to ASTM D4464-00 (2005).

[0102] This invention does not impose any particular limitation on how to obtain the average particle size of the aforementioned molecular sieves; conventional techniques in the art can be employed. This invention uses ball milling as an example.

[0103] Preferably, the molecular sieve is provided in the form of a first suspension.

[0104] 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.

[0105] 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%.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] According to a preferred embodiment of the present invention, the second liquid medium is of the same type as the first liquid medium.

[0110] 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%.

[0111] Preferably, the first binder precursor is provided in the form of a third suspension.

[0112] 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.

[0113] According to the present invention, 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.

[0114] Preferably, the weight ratio of the acid to the first binder precursor on a dry basis is 0.1-1:1.

[0115] 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.

[0116] According to a preferred embodiment of the present invention, the third liquid medium is of the same type as the first liquid medium.

[0117] 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%.

[0118] The present invention allows for a wide range of selections of molecular sieves, which can be conventional choices in the field. Preferably, the molecular sieve is selected from at least one of ZSM-5 molecular sieve, IM-5 molecular sieve, and ZSM-22 molecular sieve.

[0119] 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.

[0120] According to the present invention, preferably, the amount of water-absorbing agent used is 0.05-1.5% of the dry basis mass of the third slurry, more preferably 0.1-1%.

[0121] The present invention allows for a wide range of selections of the water-absorbing agent. In order to further improve the mechanical strength and catalytic performance of the catalyst, preferably, the water-absorbing agent is selected from at least one of sodium polyacrylate, cellulose and its derivatives and chitosan and its derivatives, and more preferably from at least one of sodium polyacrylate, sodium carboxymethyl cellulose and chitosan.

[0122] The present invention does not impose a particular limitation on the molecular weight of the absorbent, but preferably, the weight-average molecular weight of the absorbent is 50,000 to 250,000.

[0123] According to the present invention, preferably, the inlet air temperature of the spray drying in step (5) is 250-400℃, more preferably 300-400℃; and the outlet air temperature is 100-250℃, more preferably 150-200℃. Using this preferred embodiment, the spray drying temperature is suitable, which is beneficial for obtaining catalyst microspheres with the strength described in the present invention.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] Preferably, the hydrothermal aging is carried out under conditions of 100% water vapor.

[0131] The present invention will be described in detail below through embodiments.

[0132] 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;

[0133] Boehmite is a commercially available product from Shandong Aluminum Plant, with a solid content of 66.9% by weight.

[0134] ZSM-5 molecular sieve is a commercially available product from Tianjin Nanhua Catalyst Co., Ltd., with a dry basis content of 97.8% by weight.

[0135] ZSM-22 molecular sieve is a commercially available product of Tianjin Nanhua Catalyst Co., Ltd., with a dry basis content of 98.5% by weight.

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

[0137] Sodium carboxymethyl cellulose is a commercially available product of Shanghai Aladdin Biochemical Technology Co., Ltd., with a weight-average molecular weight of 250,000.

[0138] Chitosan is a commercially available product of Shanghai Aladdin Biochemical Technology Co., Ltd., with a weight-average molecular weight of 150,000.

[0139] Sodium polyacrylate is a commercially available product of Shanghai Aladdin Biochemical Technology Co., Ltd., with a weight-average molecular weight of 50,000.

[0140] Preparation Examples 1-3 illustrate the preparation of the aluminum phosphate gel described in this invention.

[0141] Preparation Example 1

[0142] 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.

[0143] Preparation Example 2

[0144] 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.

[0145] Preparation Example 3

[0146] 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.

[0147] Example 1

[0148] 6.65 kg of ZSM-5 molecular sieve with an average particle size of 0.6 μm obtained by ball milling was weighed and homogenized with deionized water to prepare a ZSM-5 molecular sieve suspension with a solid content of 33 wt%. 1.18 kg of kaolin, 0.47 kg of alumina sol, and deionized water were weighed and homogenized to prepare a kaolin suspension with a solid content of 38 wt%. 0.45 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 0.13) to prepare a boehmite suspension with a solid content of 17 wt%. The above kaolin suspension, boehmite suspension, and molecular sieve suspension were homogenized for 15 min to obtain the first slurry. 2.33 kg of alumina sol was added to the first slurry and homogenized for 5 min to obtain the second slurry. 4 kg of the aluminum phosphate gel prepared in Preparation Example 1 was added to the second slurry and stirred for 5 min to obtain the third slurry. Sodium carboxymethyl cellulose was added to the third slurry and stirred for 10 min to obtain the fourth slurry. The fourth slurry was spray-dried and then calcined at 550 °C for 2 hours to obtain the catalyst. Some conditions in the catalyst preparation process are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0149] Example 2

[0150] 6.13 kg of ZSM-5 molecular sieve with an average particle size of 0.92 μm obtained by ball milling was weighed and homogenized with deionized water to prepare a ZSM-5 molecular sieve suspension with a solid content of 36 wt%. 1.77 kg of kaolin, 0.70 kg of alumina sol, and deionized water were weighed and homogenized to prepare a kaolin suspension with a solid content of 38 wt%. 0.48 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 21 wt%. The above kaolin suspension, boehmite suspension, and molecular sieve suspension were homogenized for 15 min to obtain the first slurry. 2.09 kg of alumina sol was added to the first slurry and homogenized for 5 min to obtain the second slurry. 3.92 kg of aluminum phosphate gel prepared in Preparation Example 2 was added to the second slurry and stirred for 5 min to obtain the third slurry. Chitosan was added to the third slurry and stirred for 10 min to obtain the fourth slurry. The fourth slurry was spray-dried and then calcined at 550 °C for 2 hours to obtain the catalyst. Some conditions in the catalyst preparation process are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0151] Example 3

[0152] 7.16 kg of ZSM-22 molecular sieve with an average particle size of 0.73 μm obtained by ball milling was weighed and homogenized with deionized water to prepare a ZSM-22 molecular sieve suspension with a solid content of 31 wt%. 0.83 kg of kaolin, 0.33 kg of alumina sol, and deionized water were weighed and homogenized to prepare a kaolin suspension with a solid content of 32 wt%. 0.30 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 0.1) to prepare a boehmite suspension with a solid content of 20 wt%. The above kaolin suspension, boehmite suspension, and molecular sieve suspension were homogenized for 15 min to obtain the first slurry. 2.09 kg of alumina sol was added to the first slurry and homogenized for 5 min to obtain the second slurry. 4.09 kg of aluminum phosphate gel prepared in Preparation Example 3 was added to the second slurry and stirred for 5 min to obtain the third slurry. Sodium polyacrylate was added to the third slurry and stirred for 10 min to obtain the fourth slurry. The fourth slurry was spray-dried and then calcined at 550 °C for 2 hours to obtain the catalyst. Some conditions in the catalyst preparation process are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0153] Comparative Example 1

[0154] The method described in Example 1 was followed, except that no desiccant was added. The resulting third slurry was directly spray-dried and calcined to obtain the catalyst. Some conditions during the catalyst preparation process are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0155] Comparative Example 2

[0156] 4.09 kg of ZSM-5 molecular sieve with an average particle size of 0.66 μm obtained by ball milling was weighed and homogenized with deionized water to prepare a 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 35 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 boehmite first binder precursor on a dry basis was 0.12) to prepare a boehmite suspension with a solid content of 20 wt%. The above kaolin suspension, boehmite suspension, and molecular sieve suspension were homogenized for 15 min to obtain a first slurry. 4 kg of phosphate aluminum colloid obtained in Preparation Example 1 was added to the first slurry to obtain a second slurry. The second slurry was spray-dried and then calcined at 550 °C for 2 hours to obtain a catalyst. Some conditions in the catalyst preparation process are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0157] Comparative Example 3

[0158] 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. Some conditions in the catalyst preparation process are shown in Table 1. The catalyst composition and characteristic parameters are shown in Table 2.

[0159] Table 1

[0160]

[0161] Table 2

[0162]

[0163] Note: A indicates the mass ratio of the second adhesive to the first adhesive.

[0164] B indicates the mass ratio of the second adhesive to the third adhesive.

[0165] Test Example 1

[0166] 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 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.

[0167] Table 3

[0168]

[0169]

[0170] Note: C Num This refers to the number of carbon atoms.

[0171] Table 4

[0172]

[0173] 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.

[0174] 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 sieve is 60-85%, the mass content of clay is 5-20%, and the mass content of binder is 10-35%. The straight tube wear index of the obtained catalyst is no greater than 3% / h, and the thermal wear index is no greater than 7% / (5h). 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 mixed with a water-absorbing agent to obtain a fourth slurry with a solid content of 40-50 wt%; the water-absorbing agent is selected from at least one of sodium polyacrylate, sodium carboxymethyl cellulose and chitosan; (5) The fourth slurry is spray-dried and then roasted.

2. The catalyst according to claim 1, wherein, The aluminum-chlorine ratio of the aluminum sol is not higher than 1.

4.

3. The catalyst according to claim 2, wherein, The aluminum sol has an aluminum-chlorine ratio of 1.2-1.

3.

4. The catalyst according to claim 1, wherein, The phosphorus aluminum gel has a network structure.

5. The catalyst according to claim 1, wherein, The mass ratio of Al2O3 to P2O5 in the phosphorus aluminum gel is 0.25-0.

35.

6. The catalyst according to claim 1, wherein, The pH of the phosphate aluminum gel is 1-3.

7. The catalyst according to claim 6, wherein, The pH of the aluminum phosphate gel is 2-3.

8. The catalyst according to claim 1, 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.

9. The catalyst according to claim 8, wherein, The acid-soluble aluminum precursor is selected from at least one of boehmite, alumina, aluminum hydroxide, aluminum isopropoxide, and aluminum isobutoxide.

10. 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 5-15%, and the mass content of binder is 18-30%.

11. The catalyst according to claim 1, wherein, The mass ratio of the second adhesive to the first adhesive is 1-4; The mass ratio of the second adhesive to the first adhesive is 1.7-4.

12. The catalyst according to claim 11, wherein, The mass ratio of the second adhesive to the third adhesive is 0.3-1; The mass ratio of the second adhesive to the third adhesive is 0.3-0.

8.

13. 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.

14. The catalyst according to claim 1, wherein, The clay is selected from at least one of kaolin, halloysite, montmorillonite, and kaolin.

15. The catalyst according to any one of claims 1-14, wherein, The obtained catalyst has a straight tube wear index of 0.5-3% / h and a thermal wear index of 2.5-7% / (5h).

16. 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 mixed with a water-absorbing agent to obtain a fourth slurry with a solid content of 40-50 wt%; the water-absorbing agent is selected from at least one of sodium polyacrylate, sodium carboxymethyl cellulose and chitosan; (5) The fourth slurry is spray-dried and then calcined; 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.

17. The method according to claim 16, 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.

18. The method according to claim 17, 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 5-15%, the mass content of molecular sieve is 60-70%, and the mass content of binder is 18-30%, wherein the binder is the sum of the first binder, the second binder, and the third binder.

19. The method of claim 16, 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.

20. The method according to claim 19, 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.

21. The method according to claim 16, wherein, The aluminum-chlorine ratio of the aluminum sol is not higher than 1.

4.

22. The method according to claim 21, wherein, The aluminum sol has an aluminum-chlorine ratio of 1.2-1.

3.

23. The method according to claim 16, wherein, The phosphorus aluminum gel has a network structure.

24. The method of claim 16, wherein, The mass ratio of Al2O3 to P2O5 in the phosphorus aluminum gel is 0.25-0.

35.

25. The method according to claim 16, wherein, The pH of the phosphate aluminum gel is 1-3.

26. The method of claim 25, wherein, The pH of the aluminum phosphate gel is 2-3.

27. The method according to claim 16, 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.

28. The method according to claim 27, wherein, The acid-soluble aluminum precursor is selected from at least one of boehmite, alumina, aluminum hydroxide, aluminum isopropoxide, and aluminum isobutoxide.

29. The method according to any one of claims 16-28, wherein, The average particle size of the molecular sieve in step (1) is 0.5-2 micrometers.

30. The method according to claim 29, wherein, The average particle size of the molecular sieve in step (1) is 0.5-1 micrometer.

31. The method according to any one of claims 16-28, wherein, The second suspension is obtained by pulping clay, a second liquid medium, and optionally the remaining portion of a second binder precursor.

32. The method according to claim 31, wherein, The dry basis mass of the remaining second binder precursor is 5-15% of the dry basis mass of the clay.

33. The method according to any one of claims 16-28, wherein, The molecular sieve is selected from at least one of ZSM-5 molecular sieve, IM-5 molecular sieve and ZSM-22 molecular sieve.

34. The method according to any one of claims 16-28, wherein, The clay is selected from at least one of kaolin, halloysite, montmorillonite, and kaolin.

35. The method according to any one of claims 16-28, wherein, The amount of the water-absorbing agent used is 0.05-1.5% of the dry basis mass of the third slurry.

36. The method according to claim 35, wherein, The amount of the water-absorbing agent used is 0.1-1% of the dry basis mass of the third slurry.

37. The method according to any one of claims 16-28, wherein, The inlet air temperature of the spray drying in step (5) is 250-400℃, and the outlet air temperature is 100-250℃.

38. The method according to claim 37, wherein, The inlet air temperature of the spray drying in step (5) is 300-400℃ and the outlet air temperature is 150-200℃.

39. The use of a catalytic cracking catalyst according to any one of claims 1-15 or a catalytic cracking catalyst prepared by any one of claims 16-38 in a catalytic cracking reaction.

40. The application according to claim 39, wherein, The catalytic cracking reaction is a naphtha catalytic cracking reaction.

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