A catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline and its preparation method

Abstract

This invention belongs to the field of catalyst preparation technology, and provides a catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline, and its preparation method. The catalyst comprises a Y-type molecular sieve, rare earth elements, alumina binder, silica binder, clay, phosphorus, and an active element, wherein the active element is gallium and / or boron. The preparation method includes mixing unmodified NaY molecular sieve with alumina binder, silica binder, clay, and water, slurrying, spray drying, and calcining to obtain catalyst microspheres; then, performing rare earth ion exchange modification, mild hydrothermal ultrastability modification, SiCl4 gas-phase ultrastability modification, pore cleaning modification, phosphorus modification, and active element modification. The catalytic cracking catalyst prepared by the method described above exhibits high LCO conversion efficiency, low coke selectivity, and higher yield of BTX-rich aromatic gasoline when used for hydrotreated LCO.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, and relates to a high-yield BTX-rich aromatic gasoline low-coke catalytic cracking catalyst used in petroleum processing and its preparation method. Background Technology

[0002] Light aromatics such as benzene, toluene, and xylene (BTX) are important basic organic chemical raw materials, widely used in the production of polyesters and synthetic fibers, and demand has been strong in recent years. Currently, gasoline rich in BTX aromatics mainly comes from catalytic reforming and steam cracking processes using naphtha as feedstock. Due to the shortage of naphtha feedstock, there is a significant market gap for light aromatics.

[0003] Light cycle diesel oil (LCO) is a significant byproduct of catalytic cracking, produced in large quantities. Its hydrocarbon composition includes alkanes, cycloalkanes (containing small amounts of olefins), and aromatics. While the hydrocarbon composition varies considerably depending on the feedstock and operational severity, aromatics are the dominant component, typically comprising over 70% by mass, sometimes reaching around 90%. However, these are predominantly polycyclic aromatic hydrocarbons (PAHs), with bicyclic PAHs being the most abundant, classifying it as a low-quality diesel fraction. With evolving market demands and environmental requirements, LCO's use as a diesel blending component faces significant limitations.

[0004] Under catalytic cracking conditions, polycyclic aromatic hydrocarbons (PAHs) are difficult to ring-open and crack into light aromatic hydrocarbons. However, under hydrotreating conditions, PAHs are more easily saturated into heavy monocyclic aromatic hydrocarbons such as alkylbenzenes and cyclic alkylbenzenes (indenhydrides, tetrahydronaphthalenes, and indenes). Heavy monocyclic aromatic hydrocarbons are potential components for the production of light aromatic hydrocarbons through catalytic cracking, and can be cracked into light aromatic hydrocarbons under catalytic cracking conditions. Therefore, LCO is a potential and inexpensive resource for the production of light aromatic hydrocarbons, which can be produced via a hydrotreating-catalytic cracking technology route.

[0005] CN103923698A discloses a catalytic conversion method for producing aromatic compounds. In this method, inferior heavy cycle oil and residue oil undergo hydrotreating in the presence of hydrogen and a hydrotreating catalyst. The reaction products are separated to obtain gas, naphtha, hydrotreated diesel oil, and hydrotreated residue oil. The hydrotreated diesel oil enters a catalytic cracking unit and undergoes cracking in the presence of a catalytic cracking catalyst. The reaction products are separated to obtain dry gas, liquefied petroleum gas (LPG), catalytic gasoline rich in benzene, toluene, and xylene, catalytic light diesel oil, a fraction with a distillation range of 250–450°C, and slurry oil. The fraction with a distillation range of 250–450°C is sent to a residue oil hydrotreating unit for recycling. This method utilizes the hydrotreating conditions of residue oil to saturate the aromatic rings in inferior heavy cycle oil, enabling the hydrotreated diesel oil to undergo catalytic cracking to produce benzene, toluene, and xylene.

[0006] CN104560185A discloses a catalytic conversion method for producing gasoline rich in aromatic compounds. The method involves dividing catalytic cracking light cycle oil into light and heavy fractions. The heavy fraction is then hydrotreated to obtain a hydrotreated heavy fraction. The light and hydrotreated heavy fractions are separately introduced into a catalytic cracking unit through different nozzles, where they undergo cracking reactions in the presence of a catalytic cracking catalyst. The reaction products are separated to obtain gasoline rich in aromatic compounds and light cycle oil. This method uses a separate catalytic cracking unit to process the light fraction of the light cycle oil and the hydrotreated heavy fraction, then introduces them in layers to produce catalytic gasoline rich in benzene, toluene, and xylene.

[0007] CN104560187A discloses a catalytic conversion method for producing aromatic-rich gasoline. This method involves splitting catalytic cracking light cycle oil into light and heavy fractions. The heavy fraction is then hydrotreated to obtain a hydrotreated heavy fraction. The light and hydrotreated heavy fractions are separately fed into riser reactors of different catalytic cracking units, where they undergo cracking reactions in the presence of a catalytic cracking catalyst. The reaction products are separated to obtain a product containing aromatic-rich gasoline and light cycle oil. This method uses a separate catalytic cracking unit to process the light fraction of the light cycle oil and the hydrotreated heavy fraction to produce catalytic gasoline rich in benzene, toluene, and xylene.

[0008] In the aforementioned prior art, LCO is moderately hydrogenated to first saturate most of the polycyclic aromatic hydrocarbons into hydrogenated aromatic hydrocarbons containing a cycloalkane ring and an aromatic ring. Then, a cracking reaction is carried out in the presence of a catalytic cracking catalyst to produce BTX light aromatic hydrocarbons. However, the cracking performance of the hydrogenated aromatic hydrocarbons obtained by LCO hydrogenation is worse than that of conventional catalytic cracking feedstocks, while their hydrogen transfer performance is much higher, making them prone to carbon deposition. The conventional catalytic cracking catalysts used in the prior art cannot meet the requirements of LCO hydrogenation catalytic cracking. Summary of the Invention

[0009] One of the technical problems to be solved by this invention is to provide a high-yield BTX-rich aromatic gasoline catalytic cracking catalyst containing an ultra-stable Y-type molecular sieve, which has a high yield of BTX-rich aromatic gasoline and a low coke yield when used for hydrogenation LCO conversion.

[0010] The second technical problem to be solved by this invention is to provide a new method for preparing a cracking catalyst containing an ultrastable Y-type molecular sieve.

[0011] The third technical problem to be solved by the present invention is to provide a method for applying the catalyst.

[0012] This invention provides a low-coke, high-yield BTX-rich aromatic gasoline catalytic cracking catalyst, comprising a Y-type molecular sieve, rare earth elements, alumina binder, silica binder, clay, phosphorus, and an active element, wherein the active element is gallium and / or boron; the alumina binder has mesoporous channels; the Y-type molecular sieve has a mesoporous structure, the mesoporous channels of the Y-type molecular sieve are cleaned, and the mesopores of the Y-type molecular sieve are not blocked by the binder; the cell constant of the Y-type molecular sieve is 2.441–2.449 nm.

[0013] This invention provides a method for preparing a catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline, the method comprising:

[0014] (1) Mix unmodified NaY molecular sieve, alumina binder, clay, silica binder and water, slurry, spray dry to form, and calcine in a calcining furnace at 280-380℃ for more than 1 hour, for example 1 hour to 4 hours, to obtain catalyst microspheres A;

[0015] (2) The catalyst microspheres A are brought into contact with the rare earth solution to carry out an ion exchange reaction. After filtration and washing, catalyst microspheres B containing rare earth with reduced sodium oxide content are obtained. The rare earth solution is also called a rare earth salt solution.

[0016] (3) The catalyst microspheres B are subjected to mild hydrothermal ultrastability modification treatment and optionally dried to obtain catalyst microspheres C containing Y-type molecular sieves with reduced cell constant. The mild hydrothermal ultrastability modification treatment is to calcine the catalyst microspheres B at a temperature of 350-450°C in an atmosphere containing 40-60% volume water vapor (also called 40-60% volume water vapor atmosphere or 40-60% water vapor) for 4-6 hours.

[0017] (4) The catalyst microspheres C are reacted with SiCl4 gas, washed, and filtered to obtain catalyst microspheres D; for example: the catalyst microspheres C are reacted with SiCl4 gas at a temperature of 250-450°C, wherein the weight ratio of SiCl4 to catalyst microspheres C on a dry basis is 0.03-0.2:1, the reaction time is 10 minutes to 5 hours, and then washed and filtered to obtain catalyst microspheres D; wherein the water content of the catalyst microspheres C is preferably not more than 1% by weight; if the water content in the catalyst microspheres C is not more than 1% by weight, it can be directly used to react with silicon tetrachloride; if the water content in the catalyst microspheres C exceeds 1% by weight, the catalyst microspheres C are dried to make the water content less than 1% by weight.

[0018] (5) The catalyst microspheres D are treated with inorganic acid and organic acid, and after filtration, washing and drying, catalyst microspheres E are obtained; for example, the catalyst microspheres D are contacted with inorganic acid and organic acid solution at a temperature of 40-80°C for at least 60 minutes, for example, 60-120 minutes, then washed, filtered and optionally dried to obtain catalyst microspheres E.

[0019] (6) Contact the catalyst microsphere E with an exchange liquid containing phosphorus compounds, filter and wash to obtain catalyst microsphere F; for example, exchange the catalyst microsphere E with an exchange liquid containing phosphorus compounds at 15-100°C for more than 10 minutes, for example 10-100 min, filter and wash to obtain catalyst microsphere F.

[0020] (7) The catalyst microspheres F are brought into contact with a solution containing active elements, dried, and calcined to obtain the finished catalyst G; the active elements are gallium and / or boron.

[0021] This invention provides a method for converting hydrogenated LCO, comprising the step of contacting and reacting hydrogenated LCO with a catalytic cracking catalyst for low-coke, high-yield BTX-rich aromatic gasoline provided by this invention, or a catalytic cracking catalyst prepared according to the method for preparing a catalytic cracking catalyst for low-coke, high-yield BTX-rich aromatic gasoline provided by this invention. The preferred reaction temperature is 480–520°C, the preferred reaction time is 1–5 seconds, and the preferred catalyst-to-oil ratio is 3–10 by weight. The reactor for the reaction can be a riser reactor, a fluidized bed reactor, or a combination of these.

[0022] The catalytic cracking catalyst provided by this invention possesses both strong cracking capability and relatively weak hydrogen transfer performance, exhibiting high stability. It can enhance the cracking reaction, control the hydrogen transfer reaction, further improve the conversion efficiency of hydrotreated LCO, reduce coke selectivity, and maximize the production of catalytic gasoline rich in BTX (benzene, toluene, and xylene). It is suitable for catalytic cracking of hydrotreated LCO to achieve high yields of BTX light aromatics.

[0023] The present invention provides a method for preparing a catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline. This method can produce a catalytic cracking catalyst with larger pore volume, larger specific surface area, and better strength. The resulting catalytic cracking catalyst, when used for LCO hydrotreating, exhibits lower coke selectivity and higher yield of BTX-rich aromatic gasoline. Furthermore, it can simultaneously achieve high LCO conversion efficiency. The entire preparation process is ammonia-free, effectively solving the ammonia-nitrogen pollution problem that urgently needs to be addressed in the production of catalytic cracking catalysts.

[0024] The hydrogenation LCO conversion method provided by this invention can have low coke selectivity, high yield of BTX-rich aromatic gasoline, and high effective LCO conversion rate. Detailed Implementation

[0025] The low-coke, high-yield BTX-rich aromatic gasoline catalytic cracking catalyst provided by this invention undergoes at least three low-temperature heat treatments, acid treatments, and phosphorus modification treatments after molding. The low-temperature heat treatments are performed at temperatures above 250°C and not exceeding 450°C. The first heat treatment is calcination, the second is a mild hydrothermal treatment in the presence of rare earth elements, and the third is a heat treatment in the presence of silicon tetrachloride. The acid treatments use both inorganic and organic acids. The phosphorus modification treatments use phosphorus-containing compounds.

[0026] In the aforementioned low-coke, high-yield BTX aromatic gasoline catalytic cracking catalyst, the content of Y-type molecular sieve is 10-50% by weight on a dry basis, the content of alumina binder is 2%-15% by weight on alumina, the content of silica binder is 10-30% by weight on silica, the content of clay is 10-80% by weight on a dry basis, the content of active elements is 0.1-2% by weight, the content of rare earth elements is 1-4% by weight on RE2O3, and the content of phosphorus is 0.3-2% by weight on P2O5. The active elements are boron and / or gallium, wherein boron is calculated as B2O3 and gallium is calculated as Ga2O3. Preferably, the low-coke, high-yield BTX aromatic gasoline catalytic cracking catalyst contains, on a dry basis, 20-50 wt% Y-type molecular sieve, on a dry basis, 20-55 wt% clay, on a dry basis, 3-8 wt% (e.g., 3-5 wt%) alumina sol, on a dry basis, 10-25 wt% silica sol, on a dry basis, 1.5-3.5 wt% rare earth elements, on a dry basis, 0.3-2 wt% phosphorus, on a dry basis, and 0.1-1 wt% of the active element component, on a basis of oxides, wherein the active element is boron and / or gallium, wherein boron is calculated as B2O3 and gallium as Ga2O3.

[0027] Preferably, the catalytic cracking catalyst for low coke production and high yield of BTX aromatic gasoline contains 1-4% by weight, for example 1.5-3.5% by weight, of rare earth components, calculated as RE2O3.

[0028] Preferably, the catalytic cracking catalyst for low coke production and high yield of BTX aromatic gasoline contains 0.1 to 1% by weight, for example 0.2 to 0.6% by weight, of active element components based on oxides, wherein boron is calculated as B2O3 and gallium is calculated as Ga2O3.

[0029] The sodium oxide content in the catalytic cracking catalyst for low coke production and high yield of BTX-rich aromatic gasoline is preferably no more than 0.15% by weight.

[0030] The preferred specific surface area of ​​the low-coke, high-yield BTX aromatics-rich gasoline catalytic cracking catalyst is 280–320 m². 2 ·g -1 ).

[0031] The preferred pore volume of the low-coke, high-yield BTX aromatics-rich gasoline catalytic cracking catalyst is 0.4–0.45 mL·g. -1 ).

[0032] The wear index of the low-coke, high-yield BTX aromatics-rich gasoline catalytic cracking catalyst is preferably no more than 1.5 (%).h -1 ).

[0033] The method for preparing the low-coke, high-yield BTX-rich aromatic gasoline catalytic cracking catalyst provided by the present invention includes: preparing catalyst microspheres using raw materials including alumina binder, silica binder, unmodified NaY molecular sieve, and clay; and then sequentially performing rare earth ion exchange modification, mild hydrothermal ultrastability modification, SiCl4 gas-phase ultrastability modification, pore cleaning modification, phosphorus modification treatment, and active element modification treatment, wherein the active element is gallium and / or boron.

[0034] In the preparation method of the catalytic cracking catalyst for low coke production and high yield of BTX-rich aromatic gasoline provided by the present invention, the catalyst microspheres A may also contain other molecular sieves besides the unmodified NaY type molecular sieve. Based on the weight of the catalyst, the content of these other molecular sieves on a dry basis is, for example, 0-40% by weight, for example, 0-30% by weight, or 1-20% by weight. These other molecular sieves are selected from the molecular sieves used in catalytic cracking catalysts, such as one or more of zeolites with MFI structures, beta zeolites, and non-zeolite molecular sieves. Preferably, the MFI structured zeolites are one or more of HZSM-5, ZRP, and ZSP; the beta zeolite is Hβ; and the non-zeolite molecular sieves are one or more of aluminum phosphate molecular sieves (AlPO molecular sieves) and silica-alumina-phosphorus molecular sieves (SAPO molecular sieves).

[0035] In the catalyst microspheres A, the content of the unmodified NaY molecular sieve, on a dry basis, is 10-50% by weight, preferably 15-45% by weight, for example 25-40% by weight.

[0036] The unmodified NaY molecular sieve can be a hydrothermally synthesized NaY molecular sieve that has only been washed with water, such as industrial water, and the pH value of the filter cake of the NaY molecular sieve after washing is measured to be 7-9, preferably 7.0-8.0.

[0037] According to the present invention, the clay is selected from one or more clays used as components of cracking catalysts, such as kaolin, hydrotalcite, montmorillonite, attapulgite, diatomaceous earth, sepiolite, halloysite, soapstone, rettosite, and bentonite. These clays are well known to those skilled in the art. Preferably, the clay content in the catalytic cracking catalyst provided by the present invention is 20-55% by weight or 30-50% by weight on a dry basis.

[0038] In the cracking catalyst microspheres A, the content of the alumina binder, calculated as alumina, is 2-10% by weight, for example, 3-8% by weight or 3-6% by weight.

[0039] The alumina binder of this invention can be selected from one or more of the various forms of alumina, hydrated alumina, and alumina sol commonly used in cracking catalysts. For example, it can be selected from one or more of γ-alumina, θ-alumina, η-alumina, χ-alumina, pseudoboemite, gibbsite, boehmite, Bayerite, or alumina sol. The alumina binder can be pseudoboemite and alumina sol; for example, the catalytic cracking catalyst may contain 2-15 wt%, preferably 3-10 wt%, of alumina sol, or 0-30, 10-30, or 15-25 wt%, of pseudoboemite based on alumina. Preferably, the alumina binder is alumina sol, and the alumina sol content in the catalyst microspheres A is 2-15 wt%, preferably 3-10 wt%, or 3-8 wt%, or 3-5 wt%, based on alumina.

[0040] The silica binder is, for example, silica sol, and the silica sol content in the catalyst microspheres A is 10-30% by weight, preferably 10-25% by weight or 20-25% by weight, based on silica.

[0041] The method for preparing a low-coke, high-yield BTX-rich aromatic gasoline catalytic cracking catalyst according to the present invention involves mixing and slurrying unmodified NaY molecular sieve with a matrix. For example, water, clay, an alumina binder such as alumina sol, optional hydrochloric acid, and a silica binder can be mixed and slurryed to form a slurry. Then, an unmodified NaY molecular sieve slurry is added to the slurry and stirred until homogeneous to obtain a catalyst colloid. The catalyst colloid is then spray-dried. The mixing and slurrying method has no special requirements compared to existing methods for preparing catalytic cracking catalysts that involve mixing and slurrying molecular sieve with a matrix.

[0042] According to the preparation method of the low-coke, high-yield BTX aromatic gasoline catalytic cracking catalyst provided by the present invention, the spray drying method has no special requirements and can be carried out according to the existing spray drying method in the preparation process of cracking catalysts.

[0043] According to the method for preparing a catalytic cracking catalyst for producing BTX-rich aromatic gasoline provided by the present invention, the calcination temperature in step (1) is 280-380°C, preferably 300-350°C. The calcination time is 1 hour or more, for example 1-4 hours or 1-3 hours. Preferably, based on the weight of catalyst microspheres A, the catalyst microspheres A contain 10%-50% by weight of unmodified NaY molecular sieve (dry basis), 2-10% by weight of alumina binder (alumina basis), 10-30% by weight of silica binder (silica basis), and 10-80% by weight of clay (dry basis). More preferably, the catalyst microspheres A contain: 20-50% by weight of unmodified NaY molecular sieve (dry basis), 20-55% by weight of clay (dry basis), 3-8% by weight of alumina sol (alumina basis), and 10-30% by weight of silica sol (silica basis).

[0044] According to the preparation method of the catalytic cracking catalyst for low coke production and high yield of BTX aromatic gasoline provided by the present invention, in step (2), the temperature of the rare earth ion exchange is 20-60°C, preferably 25-45°C. The ion exchange time is preferably 90-120 minutes, and the rare earth solution is an aqueous solution of rare earth salts; the rare earth salts are preferably rare earth chlorides and / or rare earth nitrates. In one embodiment, the sodium oxide content in the catalyst microspheres B obtained after the exchange is preferably 1.5-2.5% by weight. Preferably, the ion exchange results in a rare earth content of 1-4% by weight in the obtained catalytic cracking catalyst for high coke production and high yield of BTX aromatic gasoline, for example, 1.5-3.5% by weight or 2-3% by weight.

[0045] According to the preparation method of the catalytic cracking catalyst for low-coke, high-yield BTX-rich aromatic gasoline provided by the present invention, the temperature of the mild hydrothermal ultra-stable modification treatment in step (3) is 350-450°C, preferably 370-420°C. According to the preparation method of the catalytic cracking catalyst for low-coke, high-yield BTX-rich aromatic gasoline provided by the present invention, the atmosphere conditions for the mild hydrothermal ultra-stable modification treatment in step (3) are an atmosphere containing 40-60% by volume water vapor, preferably an atmosphere containing 45-55% by volume water vapor. Other gases in the atmosphere include one or more of nitrogen, air, or CO2. According to the preparation method of the catalytic cracking catalyst for low-coke, high-yield BTX-rich aromatic gasoline provided by the present invention, the time for the mild hydrothermal ultra-stable modification treatment in step (3) is 4-6 hours, preferably 5-6 hours.

[0046] According to the preparation method of the catalytic cracking catalyst with low coke production and high yield of BTX aromatic gasoline provided by the present invention, in step (4), the catalyst microspheres C are contacted with SiCl4 gas to carry out a gas-phase ultrastable reaction. The temperature of the catalyst microspheres C and SiCl4 gas contact reaction in step (4) can be 250-450℃, preferably 280-420℃.

[0047] According to the preparation method of the catalytic cracking catalyst with low coke production and high yield of BTX aromatic gasoline provided by the present invention, the reaction time of the catalyst microspheres C and SiCl4 gas in step (4) can be 20 minutes to 4 hours, preferably 0.5 hours to 2 hours.

[0048] According to the preparation method of the catalytic cracking catalyst for low coke production and high yield of BTX aromatic gasoline provided by the present invention, the weight ratio of the reactants in the reaction between the catalyst microspheres C and SiCl4 gas in step (4) is 0.03 to 0.2:1, preferably 0.05 to 0.15:1.

[0049] According to the preparation method of the low-coke, high-yield BTX aromatic gasoline catalytic cracking catalyst provided by the present invention, in step (5), the catalyst microspheres D are acid-treated and modified by contacting inorganic acid and organic acid solutions. The catalyst microspheres D can be treated by sequentially contacting inorganic acid solutions and organic acid solutions and / or by contacting solutions containing both inorganic and organic acids. Preferably, the catalyst microspheres D are first treated by contacting an inorganic acid solution, and then by contacting a solution containing both inorganic and organic acids. In one embodiment, the catalyst microspheres D obtained in step (4) are first mixed with an inorganic acid of moderate or higher strength and water, and contacted at 40-80°C, preferably 50-60°C, for at least 60 minutes, for example, 60-120 minutes. Then, an organic acid is added, and the mixture is contacted at 40-80°C, preferably 50-60°C, for at least 60 minutes, for example, 60-120 minutes. After filtration, washing, and drying, catalyst microspheres E are obtained. Preferably, the weight ratio of the organic acid to the catalyst on a dry basis is 0.02-0.10:1, and the ratio of the amount of catalyst microspheres D, the inorganic acid of moderate or higher strength, and water is: the weight ratio of the inorganic acid of moderate or higher strength to the catalyst microspheres D on a dry basis is 0.01-0.05:1, and the weight ratio of water to the catalyst microspheres D is 6-12:1. The amount of the inorganic acid of moderate or higher strength is based on an inorganic acid solution, and the concentration of the inorganic acid solution can be 5-15% by weight, for example, 10% by weight.

[0050] According to the preparation method of the catalytic cracking catalyst for low coke production and high yield of BTX aromatic gasoline provided by the present invention, in step (5), the organic acid can be one or more of oxalic acid, malonic acid, succinic acid, methyl succinic acid, malic acid, tartaric acid, citric acid, and salicylic acid; the inorganic acid of medium strength or above can be one or more of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid.

[0051] According to the preparation method of the low-coke, high-yield BTX aromatic gasoline catalytic cracking catalyst provided by the present invention, the phosphorus modification treatment conditions in step (6) are as follows: the catalyst microspheres E obtained in step (5) are added to an exchange liquid containing phosphorus compounds, and the exchange reaction is carried out at 15-100°C for 10-100 min. After filtration and washing, catalyst microspheres F are obtained. The weight ratio of water to catalyst in the exchange liquid is (2-5):1, preferably (3-4):1, and the weight ratio of phosphorus (calculated as P2O5) to catalyst is (0.0003-0.03):1, preferably (0.003-0.02):1. The phosphorus compounds are, for example, one or more of ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

[0052] According to the preparation method of the catalytic cracking catalyst for low coke production and high yield of BTX aromatic gasoline provided by the present invention, the solution containing active elements in step (7) is preferably an aqueous solution of gallium salt and / or an aqueous solution of boron compound.

[0053] The gallium salt is one or more of gallium sulfate, nitrate, and chloride. The boron compound is a boric acid, borate, metaborate, or polyborate, or a combination of two, three, or four of them.

[0054] According to the preparation method of the catalytic cracking catalyst for low coke production and high yield of BTX aromatic gasoline provided by the present invention, when the active element is gallium, the catalyst microspheres F are contacted with a solution containing the active element. In one embodiment, the catalyst microspheres F are mixed evenly with an aqueous solution of gallium salt and allowed to stand at 15-40°C for 24-36 hours. The weight ratio of gallium in the aqueous solution of gallium salt (calculated as Ga2O3), water in the aqueous solution of gallium salt, and catalyst microspheres F on a dry basis is (0.0004-0.01):(2-3):1.

[0055] According to the method for preparing a catalytic cracking catalyst for producing BTX-rich aromatic gasoline provided by the present invention, when the active element is boron, the catalyst microspheres F are contacted with a solution containing the active element. In one embodiment, the catalyst microspheres E are heated to 60-99°C and then contacted with a boron compound in an aqueous solution at 60-99°C for 1-2 hours, wherein the weight ratio of boron (calculated as B2O3), water, and catalyst microspheres F (based on dry weight) is (0.0015-0.015):(2.5-5):1.

[0056] According to the method for preparing a catalytic cracking catalyst for producing BTX-rich aromatic gasoline provided by the present invention, when the active elements are boron and gallium, the catalyst microspheres F are contacted with a solution containing the active elements. In one embodiment, the catalyst microspheres F are heated to 80-95°C and then contacted with a boron compound in a first aqueous solution at 80-95°C for 1-2 hours. The weight ratio of boron (calculated as B2O3), water, and catalyst microspheres F (on a dry basis) in the first aqueous solution is (0.0015-0.01):(2.5-5):1. After filtration, the obtained catalyst material is mixed evenly with a second aqueous solution containing gallium salt and then allowed to stand at 15-40°C for 24-36 hours. The weight ratio of gallium (calculated as Ga2O3), water, and catalyst microspheres F (on a dry basis) in the second aqueous solution is (0.0004-0.007):(2-3):1.

[0057] The following embodiments will further illustrate the present invention, but are not intended to limit the invention.

[0058] In the examples and comparative examples, the unmodified NaY molecular sieve (also referred to as NaY molecular sieve or NaY zeolite) was provided by Qilu Branch of Sinopec Catalyst Co., Ltd., with a sodium oxide content of 13.5 wt%, a framework silicon-to-aluminum ratio (SiO2 / Al2O3 molar ratio) of 4.6, a cell constant of 2.470 nm, and a relative crystallinity of 90%. The original synthesized NaY molecular sieve was washed with industrial water until the filter cake pH value was 7.6. Ammonium phosphate, diammonium hydrogen phosphate, and gallium nitrate were chemically pure reagents produced by Beijing Chemical Plant. Rare earth chloride and rare earth nitrate (denoted as RECl3 and RE(NO3)3, respectively, a mixed rare earth with a La2O3 content of 33.6 wt% and a Ce2O3 content of 66.4 wt%) were industrial products produced by Baotou Steel Rare Earth Co., Ltd. Boehmite is an industrial product produced by Shandong Aluminum Plant, with a solid content of 61% by weight; kaolin is a cracking catalyst-specific kaolin produced by Suzhou China Kaolin Company, with a solid content of 76% by weight; alumina sol is provided by Qilu Branch of Sinopec Catalyst Co., Ltd., of which alumina content is 21% by weight.

[0059] Analytical methods: In each comparative example and embodiment, the elemental content of the catalyst was determined by X-ray fluorescence spectrometry; the cell constant and relative crystallinity of the zeolite in the catalyst were determined by X-ray powder diffraction (XRD) using the RIPP 145-90 and RIPP 146-90 standard methods (see *Analytical Methods in Petrochemical Industry* (RIPP Test Methods), edited by Yang Cuiding et al., Science Press, 1990). The specific surface area of ​​the catalyst was determined using an Autosorb-1 nitrogen adsorption-desorption instrument from Quanta Computer, USA, according to GB / T 5816-1995 method, with the sample degassed at 300℃ for 6 hours before testing. The total pore volume of the catalyst was determined according to the RIPP 151-90 standard method (see *Analytical Methods in Petrochemical Industry* (RIPP Test Methods), edited by Yang Cuiding, Science Press, 1990). The wear index of the catalyst was tested according to the RIPP 29-90 standard method (see "Analytical Methods in Petrochemical Industry" (RIPP Test Methods), edited by Yang Cuiding, Science Press, published in 1990). The wear index is used to characterize the wear resistance; the smaller the wear index, the better the wear resistance.

[0060] Unless otherwise specified, the chemical reagents used in the comparative examples and embodiments are chemically pure.

[0061] Example 1

[0062] (1) 216 kg of decationized water was added to a stirred tank. Then, under stirring, the following gelling materials were added sequentially: 66.6 kg of kaolin (76% solid content, purchased from Suzhou Kaolin Company), 30.3 kg of alumina sol (21.5% alumina content, provided by Qilu Branch of Sinopec Catalyst Co., Ltd.), and 114.4 kg of silica sol (25% SiO2 content, product of Qilu Branch of Sinopec Catalyst Co., Ltd., pH 2.5). The mixture was stirred for 30 minutes. Then, 35.1 kg of unmodified NaY molecular sieve (on a dry basis) was added and stirred for 60 minutes. The mixture was then spray-dried and calcined in a calcining furnace at 320°C for 1 hour to obtain catalyst microspheres A1.

[0063] (2) The catalyst microspheres A1 prepared above were added to 1300L of decation aqueous solution and stirred to mix evenly. 12.2L of RECl3 solution (the rare earth solution concentration was 305g / L based on RE2O3) was added, stirred, heated to 35℃ and kept for 1h, then filtered and washed. The filter cake was dried at 120℃ to obtain rare earth catalyst microspheres B1 with reduced sodium oxide content.

[0064] (3) The above catalyst microspheres B1 were calcined at 425°C in an atmosphere containing 45% water vapor (a mixture of 45% water vapor and 55% air) for 5.0 h. After that, they were dried to make the water content less than 1% by weight, and the catalyst microspheres C1 containing molecular sieves with reduced cell constant were obtained.

[0065] (4) SiCl4 gas that has been heated and vaporized was introduced into the catalyst microspheres C1 at a weight ratio of 0.065:1 based on dry basis. The reaction was carried out at a temperature of 405℃ for 45 min. After that, the mixture was washed with 1300 L of decation water and then filtered to obtain catalyst microspheres D1.

[0066] (5) The catalyst microspheres D1 were modified by contacting an acid solution with an acid treatment. Specifically, the catalyst microspheres D1 were first mixed with 10% hydrochloric acid and water and contacted at 55°C for 70 minutes. Then, citric acid was added and contacted at 55°C for 75 minutes. After filtration and washing, catalyst microspheres E1 were obtained. The weight ratio of citric acid to catalyst microspheres D1 on a dry basis was 0.027:1, the weight ratio of 10% hydrochloric acid to catalyst microspheres D1 on a dry basis was 0.031:1, and the weight ratio of water to catalyst microspheres D1 was 10:1.

[0067] (6) The above-mentioned catalyst microsphere E1 filter cake was directly added to the exchange solution containing ammonium phosphate. The amount of catalyst added was: the weight ratio of phosphorus (calculated as P2O5) to catalyst microsphere E1 on a dry basis was 0.013:1, and the weight ratio of water to catalyst microsphere E1 on a dry basis was 2.5:1. The exchange reaction was carried out at 50°C for 50 min, filtered, washed, and catalyst microsphere F1 was obtained.

[0068] (7) Take 5 kg of the catalyst microspheres F1 (dry basis) and add them to 10 L of a solution containing 62.5 g of Ga(NO3)3·9H2O under stirring to impregnate the gallium component. After stirring evenly, let it stand at room temperature for 24 h. Then, stir for 20 min to make it evenly mixed. After that, transfer the slurry to a rotary evaporator for water bath heating and rotary evaporation to dry it. Then, put the dried material into a muffle furnace and calcine it at 550 °C for 2.5 h to obtain the catalytic cracking catalyst provided by the present invention, denoted as SCAT-1. Its performance analysis results are shown in Table 1.

[0069] Example 2

[0070] (1) 223 kg of decationized water was added to the catalyst gelling vessel. Then, under stirring, the following gelling raw materials were added sequentially: 78.7 kg of kaolin (76% solid content, purchased from Suzhou Kaolin Company), 24.2 kg of alumina sol (21.5% alumina content, provided by Qilu Branch of Sinopec Catalyst Co., Ltd.), and 130 kg of silica sol (25% SiO2 content, product of Qilu Branch of Sinopec Catalyst Co., Ltd., pH 2.5). The mixture was stirred for 30 minutes. Then, 32.5 kg of unmodified NaY molecular sieve (on a dry basis) was added and stirred rapidly for 60 minutes. The mixture was then spray-dried and calcined in a calcining furnace at 350°C for 1 hour to obtain catalyst microspheres A2.

[0071] (2) The catalyst microspheres A2 (on a dry basis) prepared above were added to 1300L of decation aqueous solution and stirred to mix evenly. 9.7L of RECl3 solution (the rare earth solution concentration was 305g / L based on RE2O3) was added, stirred, heated to 45℃ and held for 1h, then filtered and washed. The filter cake was dried at 120℃ to obtain rare earth catalyst microspheres B2 with reduced sodium oxide content.

[0072] (3) The above catalyst microspheres B2 were calcined at 375°C in an atmosphere containing 65% water vapor for 5.6 hours. After that, they were dried to make the water content less than 1% by weight, and the catalyst microspheres C2 containing molecular sieves with reduced cell constant were obtained.

[0073] (4) According to the weight ratio of SiCl4:catalyst microspheres C2 (dry basis) = 0.085:1, SiCl4 gas that has been heated and vaporized was introduced and reacted at a temperature of 340℃ for 1.8h. After that, it was washed with 1300L of decation water and then filtered to obtain catalyst microspheres D2 filter cake.

[0074] (5) The catalyst microspheres D2 filter cake is contacted with an acid solution for acid treatment modification; wherein, the catalyst microspheres D2 are first mixed with hydrochloric acid of 10% by weight and water, and contacted at 55°C for 70 minutes, then solid citric acid is added, and contacted at 55°C for 65 minutes, and after filtration, washing and drying, the catalytic cracking catalyst product E2 provided by the present invention is obtained; wherein, the weight ratio of citric acid to catalyst on a dry basis is 0.023:1, the weight ratio of hydrochloric acid of 10% by weight to catalyst microspheres D2 on a dry basis is 0.034:1, and the weight ratio of water to catalyst microspheres D2 on a dry basis is 10:1.

[0075] (6) The above-mentioned catalyst microsphere E2 filter cake was directly added to the exchange solution containing diammonium hydrogen phosphate. The amount of catalyst added was: the weight ratio of phosphorus (calculated as P2O5) to catalyst microsphere E2 on a dry basis was 0.012:1, and the weight ratio of water to catalyst microsphere E2 on a dry basis was 3.0:1. The exchange reaction was carried out at 60°C for 50 min, filtered, washed, and catalyst microsphere F2 was obtained.

[0076] (7) Take 5 kg (dry basis) of catalyst microspheres F2 and add them to the exchange tank while stirring. Add 12.5 L of chemical water (decationized water with pH 3.5). Then heat the slurry to 70 °C, add 28.2 g of boric acid, stir for 1 h, and filter. Then add the filter cake to 10 L of a solution containing 34.5 g of Ga(NO3)3·9H2O while stirring to impregnate the gallium component. After stirring evenly, let it stand at room temperature for 24 h. Then stir for 30 min to mix evenly. After that, transfer the slurry to a rotary evaporator for water bath heating and rotary evaporation to dryness. Then, put the dried material into a muffle furnace and calcine at 550 °C for 2.5 h. The catalyst provided by this invention is obtained and is designated as SCAT-2. Its performance analysis results are shown in Table 1.

[0077] Example 3

[0078] (1) 247 kg of decationized water was added to the catalyst gelling vessel. Then, under stirring, the following gelling raw materials were added sequentially: 71.8 kg of kaolin (76% solid content, purchased from Suzhou Kaolin Company), 18.1 kg of alumina sol (21.5% alumina content, provided by Qilu Branch of Sinopec Catalyst Co., Ltd.), and 135 kg of silica sol (25% SiO2 content, product of Qilu Branch of Sinopec Catalyst Co., Ltd., pH value 2.5). The mixture was stirred for 30 minutes. Then, 37.7 kg of unmodified NaY molecular sieve (on a dry basis, provided by Qilu Branch of Sinopec Catalyst Co., Ltd.) was added and stirred for 60 minutes. The mixture was then spray-dried and calcined in a calcining furnace at 300°C for 1 hour to obtain catalyst microspheres A3.

[0079] (2) The catalyst microspheres A3 prepared above were added to 1300L of decation aqueous solution and stirred to mix evenly. 13.6L of RECl3 solution (the rare earth solution concentration was 305g / L based on RE2O3) was added, stirred, heated to 35℃ and kept for 1h, then filtered and washed. The filter cake was dried at 120℃ to obtain rare earth catalyst microspheres B3 with reduced sodium oxide content.

[0080] (3) The catalyst microspheres B3 were calcined at 405°C in an atmosphere containing 48% water vapor for 5 hours. After that, they were dried to make the water content less than 1% by weight, and the catalyst microspheres C3 containing molecular sieves with reduced cell constant were obtained.

[0081] (4) According to the weight ratio of SiCl4:catalyst microspheres C3 (dry basis) = 0.10:1, SiCl4 gas that has been heated and vaporized was introduced and reacted at a temperature of 368℃ for 55 min. After that, it was washed with 1300L of decation water, filtered, and the filter cake was dried at 120℃ for 5 hours to obtain catalyst microspheres D3.

[0082] (5) The catalyst microspheres D3 were modified by contacting an acid solution. Specifically, the catalyst microspheres D3 were first mixed with 7% by weight sulfuric acid and water, and contacted at 55°C for 75 minutes. Then, solid oxalic acid was added, and the mixture was contacted at 55°C for 70 minutes. After filtration, washing, and drying, catalyst microspheres E3 were obtained. The weight ratio of oxalic acid to catalyst microspheres D3 on a dry basis was 0.024:1, the weight ratio of 7% by weight sulfuric acid to catalyst microspheres D3 on a dry basis was 0.027:1, and the weight ratio of water to catalyst microspheres was 10:1.

[0083] (6) The above catalyst microsphere E3 filter cake was directly added to the exchange solution containing diammonium hydrogen phosphate. The amount of catalyst added was: the weight ratio of phosphorus (calculated as P2O5) to catalyst was 0.006, and the weight ratio of water to molecular sieve was 2.8. The exchange reaction was carried out at 70°C for 30 min, filtered, washed, and catalyst microsphere F3 was obtained.

[0084] (7) 5 kg (dry basis) of catalyst microspheres F3 were added to an exchange tank, followed by 10 L of chemical water. The catalyst slurry was then heated to 80 °C, and 49.2 g of boric acid was added. After stirring for 1 h, the mixture was filtered. The filtered sample was first dried at 130 °C for 5 h, and then calcined at 380 °C for 3.5 h to obtain the catalyst product provided by this invention, designated as SCAT-3. Its performance analysis results are shown in Table 1. The chemical water was industrial water that had undergone acidic resin ion exchange and then neutralized with ammonia water to a pH of 6.5-7.5.

[0085] Comparative Example 1

[0086] Add 2000 kg (dry basis weight) of NaY-type zeolite by weight% to a container containing 20 m³ of... 3After being stirred evenly in a primary water exchange tank at 25°C, 708L of RECl3 solution (the rare earth concentration in the RECl3 solution is 305g / L, calculated as RE2O3) is added. After stirring for 60 minutes, the mixture is filtered, washed, and the filter cake is sent to a flash drying oven for drying. Then, it is sent to a calcination oven and calcined for 6 hours at 380°C with 60% water vapor (the atmosphere contains 60% by volume water vapor). Then, it is calcined for 2.5 hours at 500°C in a dry air atmosphere (water vapor content less than 1% by volume) to reduce its water content to less than 1% by weight. Finally, the molecular sieve material is directly sent to a continuous gas-phase ultrastable reactor for gas-phase ultrastable reaction. The gas-phase ultrastable reaction process of molecular sieves in a continuous gas-phase ultrastable reactor and its subsequent tail gas absorption process were carried out according to the method of Example 1 disclosed in patent CN103787352A. The process conditions were: SiCl4:Y-type molecular sieve with reduced cell constant weight ratio = 0.55:1, molecular sieve feed rate of 800 kg / h, and reaction temperature of 410℃. After the gas-phase ultrastable reaction, the molecular sieve material was separated by a gas-solid separator and sent to a secondary exchange tank, which was pre-filled with 20 m³ of gas. 3 Water was added to the molecular sieve material in the secondary exchange tank at a weight of 2000 kg (dry basis), and stirred until homogeneous. Then, 0.65 ml of 10% hydrochloric acid was added. 3 The temperature was raised to 90℃ and stirred for 70 minutes. Then, 135 kg of citric acid was added, and stirring continued at 90℃ for another 60 minutes. After filtration and washing, the molecular sieve filter cake was directly added to an exchange solution containing ammonium phosphate. The weight ratio of phosphorus (as P2O5) to molecular sieve was 0.015, and the weight ratio of water to molecular sieve was 2.8. The exchange reaction was carried out at 70℃ for 30 minutes. After filtration and washing, the filter cake was then added to a 4000 L solution containing 83.5 kg of citric acid while stirring. Gallium components were impregnated in a Ga(NO3)3·9H2O solution. The modified Y molecular sieve was stirred evenly with the solution containing Ga(NO3)3 and allowed to stand at room temperature for 24 hours. Then, the slurry containing the modified Y molecular sieve and Ga(NO3)3 was stirred for 20 minutes to mix evenly. The mixture was then transferred to a rotary evaporator for slow and uniform heating and rotary evaporation to dryness. After that, the dried material was placed in a muffle furnace and calcined at 550°C for 2.5 hours to obtain the modified Y-type molecular sieve, denoted as DZ1.

[0087] 18.6 kg of alumina sol with an alumina content of 21.5 wt% was added to 111.2 kg of decationized water, and stirring was started. 44.2 kg of kaolin with a solid content of 76 wt% was added and dispersed for 60 minutes. Then, 46 kg of silica sol (SiO2 content 25 wt%, provided by Sinopec Catalyst Co., Ltd. Qilu Branch) was added and stirred for 30 minutes. Next, 24 kg of finely ground DZ1 molecular sieve (dry basis) was added, and the mixture was rapidly stirred for 60 minutes. After spray drying, calcination, and washing, the catalyst, denoted as DC1, was obtained. The DC1 catalyst, on a dry basis, contained 30 wt% DZ1 molecular sieve, 42 wt% kaolin, 23 wt% silica sol binder, and 5 wt% alumina sol. Its performance analysis results are shown in Table 1.

[0088] Comparative Example 2

[0089] 2000 kg (dry basis weight) of NaY-type zeolite with a SiO2 / Al2O3 ratio of 4.6 was added to a container containing 20 m³ of... 3 After being stirred evenly in a primary water exchange tank at 25°C, 821L of RECl3 solution (the rare earth concentration in the RECl3 solution is 305g / L, calculated as RE2O3) is added. After stirring for 60 minutes, the mixture is filtered, washed, and the filter cake is sent to a flash drying oven for drying. Then, it is sent to a calcination oven and calcined for 6 hours at 420°C with 48% water vapor (the atmosphere contains 48% water vapor by volume and 52% air by volume). Then, it is calcined for 2.5 hours at 500°C in a dry air atmosphere (water vapor content less than 1% by volume) to reduce its water content to less than 1% by weight. Finally, the molecular sieve material is directly sent to a continuous gas-phase ultrastable reactor for gas-phase ultrastable reaction. The gas-phase ultrastable reaction process of molecular sieve in a continuous gas-phase ultrastable reactor and its subsequent tail gas absorption process were carried out according to the method of Example 1 disclosed in patent CN103787352A. The process conditions were: SiCl4:Y-type zeolite weight ratio = 0.45:1, molecular sieve feed rate of 800 kg / h, and reaction temperature of 380℃. After the gas-phase ultrastable reaction, the molecular sieve material was separated by a gas-solid separator and sent to a secondary exchange tank. The secondary exchange tank was pre-filled with 20 m³ of gas. 3 Water was added to the molecular sieve material in the secondary exchange tank at a weight of 2000 kg (dry basis), and stirred until homogeneous. Then, 0.7 mg of 10% hydrochloric acid was added. 3 The mixture was heated to 85°C and stirred for 60 minutes. Then, 142 kg of citric acid was added, and stirring was continued at 85°C for another 60 minutes. After filtration and washing, the filter cake was transferred to an exchange tank, and 5 ml of [unspecified substance] was added. 3The molecular sieve slurry was then heated to 70°C with chemical water, followed by the addition of 43.9 kg of boric acid. After stirring for 1 hour, the mixture was filtered and washed. The molecular sieve filter cake was then directly added to an exchange solution containing ammonium phosphate. The weight ratio of phosphorus (as P2O5) to molecular sieve was 0.04, and the weight ratio of water to molecular sieve was 2.5. The exchange reaction was carried out at 50°C for 60 minutes. After filtration and washing, the filter cake was then added to 4000 L of a solution containing 63 kg of Ga(NO3)2. 3) The gallium component was impregnated in a solution of 3·9H2O. The modified Y molecular sieve was stirred evenly with a solution containing Ga(NO3)3 and then allowed to stand at room temperature for 24 hours. Then, the slurry containing the modified Y molecular sieve and Ga(NO3)3 was stirred for 20 minutes to make it evenly mixed. After that, the slurry was transferred to a rotary evaporator for water bath heating and rotary evaporation to dryness. Then, the dried material was placed in a muffle furnace and calcined at 550℃ for 2.5 hours to obtain the modified Y-type molecular sieve, denoted as DZ2.

[0090] Following the preparation method of Comparative Example 1, DZ2 molecular sieve, kaolin, water, silica sol binder, and alumina sol were slurried to form a catalyst slurry. This slurry was then spray-dried, calcined, washed, and dried to prepare microsphere catalysts. The prepared catalytic cracking catalyst is designated DC2. On a dry basis, the obtained DC2 catalyst contains 30% by weight of DZ2 molecular sieve, 42% by weight of kaolin, 23% by weight of silica sol binder, and 5% by weight of alumina sol. Its performance analysis results are shown in Table 1.

[0091] Comparative Example 3

[0092] 2000 kg (dry basis weight) of NaY-type zeolite with a SiO2 / Al2O3 ratio of 4.6 was added to a container containing 20 m³ of... 3In the primary exchange tank for decation water, the mixture was stirred evenly at 90°C, and then 548 L of RECl3 solution (the rare earth concentration in the RECl3 solution was 305 g / L, calculated as RE2O3) was added and stirred for 60 min. After filtration and washing, the filter cake was sent to a flash drying oven for drying. Then, it was sent to a calcination furnace and calcined for 5.5 h at a temperature (atmosphere temperature) of 440°C and a 75% (v / v) water vapor atmosphere. Then, the molecular sieve material was sent to the calcination furnace for calcination and drying treatment at a calcination temperature of 500°C and a dry air atmosphere for 2 h to reduce its water content to less than 1% (w / w). Finally, the molecular sieve material was directly sent to a continuous gas-phase ultrastable reactor for gas-phase ultrastable reaction. The gas-phase ultrastable reaction process of molecular sieve in a continuous gas-phase ultrastable reactor and its subsequent tail gas absorption process were carried out according to the method of Example 1 disclosed in patent CN103787352A. The process conditions were: SiCl4:Y-type zeolite weight ratio = 0.30:1, molecular sieve feed rate of 800 kg / h, and reaction temperature of 480℃. After the gas-phase ultrastable reaction, the molecular sieve material was separated by a gas-solid separator and sent to a secondary exchange tank, which was pre-filled with 20 m³ of gas. 3 The deionized water was added to the molecular sieve material in the secondary exchange tank at a weight of 2000 kg (dry basis), stirred evenly, and then 0.85 ml of a 7% by weight sulfuric acid solution was added. 3 The temperature was raised to 90℃ and stirred for 85 minutes. Then, 68 kg of citric acid and 55 kg of tartaric acid were added. After stirring at 90℃ for another 70 minutes, the mixture was filtered and washed. The molecular sieve filter cake was then directly added to an exchange solution containing ammonium phosphate. The weight ratio of phosphorus (as P2O5) to molecular sieve was 0.04, and the weight ratio of water to molecular sieve was 2.5. The exchange reaction was carried out at 50℃ for 60 minutes. After filtration and washing, the filter cake was added to an exchange tank, and 6000 L of chemical water was added. The molecular sieve slurry was then heated to 80℃, and 66.5 kg of boric acid was added. After stirring for 1 hour, the mixture was filtered. The filtered sample was first dried at 130℃ for 5 hours and then calcined at 380℃ for 3.5 hours to obtain the modified Y-type molecular sieve, denoted as DZ3.

[0093] DZ3 molecular sieve, kaolin, water, boehmite binder, and alumina sol were mixed and slurry-formed using conventional methods for preparing catalytic cracking catalysts. The resulting slurry was then spray-dried to prepare microsphere catalysts, denoted as DC3. On a dry basis, the DC3 catalyst contained 30 wt% DZ3 molecular sieve, 42 wt% kaolin, 25 wt% boehmite, and 3 wt% alumina sol. Its performance analysis results are shown in Table 1.

[0094] 11.44 kg of alumina sol with an alumina content of 21 wt% was added to 25.06 kg of decationized water, and stirring was started. Then, 44.21 kg of kaolin with a solid content of 76 wt% was added and dispersed for 60 minutes. 32.78 kg of boehmite with an alumina content of 61 wt% was added to 130.33 kg of decationized water, and 3.4 L of 36% hydrochloric acid was added while stirring. After acidification for 60 minutes, the dispersed kaolin slurry was added, followed by 24 kg of finely ground DZ3 molecular sieve (dry basis). After stirring evenly, the mixture was spray-dried, calcined, and washed. The resulting catalyst, denoted as DC3, was dried. The DC3 catalyst, on a dry basis, contained 30 wt% DZ3 molecular sieve, 42 wt% kaolin, 25 wt% boehmite, and 3 wt% alumina sol.

[0095] Examples 4-6

[0096] Examples 4-6 illustrate the catalytic cracking reaction performance of the catalytic cracking catalyst provided by the present invention.

[0097] SCAT-1, SCAT-2, and SCAT-3 catalysts were aged at 800℃ and 100% steam for 12 h. Their catalytic cracking performance for processing hydrotreated LCO was evaluated in a small fixed fluidized bed reactor (ACE). Cracking gas and product oil were collected and analyzed by gas chromatography. The catalyst loading was 9 g, the reaction temperature was 500℃, and the weight hourly space velocity (WHSV) was 16 h⁻¹. -1 The agent-to-oil ratio (by weight) is shown in Table 3, the properties of the feedstock for the ACE experiment are shown in Table 2, and the evaluation results are shown in Table 3. The effective conversion rate of hydrogenated LCO = LPG yield + gasoline yield.

[0098] Comparative Examples 4-6

[0099] Comparative Examples 4-6 illustrate the catalytic cracking performance of the ultrastable Y-type zeolites prepared by the methods provided in Comparative Examples 1-3.

[0100] After aging DC1, DC2, and DC2 catalysts at 800°C with 100% steam for 12 hours, their catalytic cracking performance for processing hydrogenated LCO was evaluated in a small fixed fluidized bed reactor (ACE). The evaluation method is described in Example 4. The feedstock properties for the ACE experiment are shown in Table 2, and the evaluation results are listed in Table 3. The effective conversion rate of hydrogenated LCO is defined as: LPG yield + gasoline yield.

[0101] Table 1

[0102] Example number Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Sample number SCAT-1 SCAT-2 SCAT-3 DC1 DC2 DC3 <![CDATA[Na2O content / wt%]]> 0.051 0.042 0.073 0.076 0.065 0.24 <![CDATA[Content of RE2O3 / wt%]]> 2.45 1.95 2.75 2.48 2.83 1.85 <![CDATA[P2O5 content / wt%]]> 1.25 1.14 0.55 0.43 1.15 1.15 <![CDATA[Ga2O3 content / wt%]]> 0.27 0.15 - 0.27 0.20 - <![CDATA[B2O3 content / wt%]]> - 0.26 0.54 - 0.36 0.55 Unit cell constant (nm) 2.446 2.443 2.447 2.443 2.445 2.447 Relative crystallinity (%) 19.8 19.0 20.5 16.7 17.1 16.5 <![CDATA[Wear index (%, h -1 )]]> 1.0 0.9 1.1 2.5 2.2 2.3 <![CDATA[Specific surface area (m 2 ·g -1 )]]> 296 289 301 255 258 257 <![CDATA[Pore volume (mL·g -1 )]]> 0.41 0.40 0.43 0.37 0.36 0.36

[0103] As shown in Table 1, the catalytic cracking catalyst provided by the present invention has a larger pore volume and specific surface area, as well as better strength. Furthermore, the catalyst has a low sodium oxide content, a high relative crystallinity of the molecular sieve, and no ammonia nitrogen pollution during catalyst preparation.

[0104] Table 2 Properties of hydrogenated LCO

[0105]

[0106] Table 3

[0107] Instance number Example 4 Example 5 Example 6 Comparative Example 4 Comparative Example 5 Comparative Example 6 Sample number SCAT-1 SCAT-2 SCAT-3 DC1 DC2 DC3 Agent-to-oil ratio 5 5 5 5 5 5 Reaction temperature / ℃ 500 500 500 500 500 500 Product Distribution / Weight % dry air 1.18 1.3 1.19 1.65 1.83 1.86 Liquefied gas 18.72 18.28 17.19 15.65 15.74 14.15 coke 1.02 0.96 0.83 2.11 2.44 1.97 gasoline 58.09 57.56 57.41 55.18 55.47 55.71 diesel fuel 19.59 20.59 21.95 23.54 22.81 24.26 heavy oil 1.4 1.31 1.43 1.87 1.71 2.05 total 100 100 100 100 100 100 BTX aromatic content in gasoline / % 72.75 73.83 73.46 69.79 71.86 70.76 Effective conversion rate of hydrogenated LCO / % 76.81 75.84 74.6 70.83 71.21 69.86

[0108] As can be seen from the results listed in Table 3, the catalytic cracking catalyst provided by the present invention has significantly lower coke selectivity, significantly higher effective conversion rate of hydrogenated LCO, higher gasoline yield, and significantly increased BTX aromatic content in gasoline.

Claims

1. A low-coke, high-yield BTX-rich aromatic gasoline catalytic cracking catalyst, comprising an alumina binder, a silica binder, a Y-type molecular sieve component, clay, rare earth elements, phosphorus, and an active element, wherein the active element is gallium and / or boron; wherein the low-coke, high-yield BTX-rich aromatic gasoline catalytic cracking catalyst contains 10-80% by weight (dry basis), 2-15% by weight (dry basis) of alumina binder, 10-30% by weight (dry basis) of silica binder, and 1% by weight (dry basis) of Y-type molecular sieve. The alumina binder comprises 0-50% by weight, with rare earth elements accounting for 1-4% by weight (RE2O3), phosphorus accounting for 0.3-2% by weight (P2O5), and active elements accounting for 0.1-2% by weight (oxides), wherein boron is calculated as B2O3 and gallium as Ga2O3; the alumina binder has mesoporous channels; the Y-type molecular sieve has a mesoporous structure, the mesoporous channels of the Y-type molecular sieve are cleaned and not blocked by the binder, and the cell constant of the Y-type molecular sieve is 2.441-2.449 nm; its preparation method includes the following steps: (1) Mix unmodified NaY molecular sieve, alumina binder, silica binder, clay and water, slurry, spray dry, and calcine at 280-380℃ for more than 1 hour to obtain catalyst microspheres A; (2) The catalyst microspheres A are brought into contact with a rare earth solution to carry out an ion exchange reaction. After filtration, washing and drying, catalyst microspheres B are obtained. (3) The catalyst microspheres B are subjected to mild hydrothermal ultrastability modification treatment and optionally dried to obtain catalyst microspheres C; The mild hydrothermal ultrastability modification treatment involves calcining the catalyst microspheres B at a temperature of 350–450°C in an atmosphere containing 40–60% by volume water vapor for 4–6 hours; wherein the water content of the catalyst microspheres C does not exceed 1% by weight. (4) The catalyst microspheres C are brought into contact with SiCl4 gas at a temperature of 250-450℃, washed, and filtered to obtain catalyst D; wherein the weight ratio of SiCl4 to catalyst microspheres C on a dry basis is 0.03-0.2:

1. (5) The catalyst microspheres D are treated with inorganic acid and organic acid, and after filtration, washing and drying, catalyst microspheres E are obtained; (6) Contact the catalyst microspheres E with an exchange liquid containing phosphorus compounds, filter and wash to obtain catalyst microspheres F; (7) Contact the catalyst microspheres F with a solution containing the active element, dry and calcine; the active element is gallium and / or boron.

2. The low-coke, high-yield BTX-rich aromatic gasoline catalytic cracking catalyst according to claim 1, characterized in that, After molding, it undergoes at least three low-temperature heat treatments, acid treatments, and phosphorus modification treatments; the low-coke, high-yield BTX aromatic gasoline-rich catalytic cracking catalyst has a sodium oxide content of no more than 0.15% by weight and a specific surface area of ​​280–320 m². 2 ·g -1 The wear index does not exceed 1.5%. -1 The pore volume is 0.4–0.45 mL·g. -1 .

3. The low-coke, high-yield BTX-rich aromatic gasoline catalytic cracking catalyst according to claim 1 or 2, characterized in that, The low-coke, high-yield BTX aromatic gasoline catalytic cracking catalyst contains, on a dry basis, 20-50 wt% Y-type molecular sieve, 20-55 wt% clay, on a dry basis, 3-8 wt% alumina sol, 10-25 wt% silica sol, 1.5-3.5 wt% rare earth elements, on a RE2O3 basis, 0.3-2 wt% phosphorus, on a P2O5 basis, and 0.1-1 wt% of the active element component, on an oxide basis. The active element is boron and / or gallium, wherein boron is calculated as B2O3 and gallium as Ga2O3.

4. A method for preparing a catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline, comprising the following steps: (1) Mix unmodified NaY molecular sieve, alumina binder, silica binder, clay and water, slurry, spray dry, and calcine at 280-380℃ for more than 1 hour to obtain catalyst microspheres A; based on the weight of catalyst microspheres A, the catalyst microspheres A contain 2-15% by weight of alumina binder, 10%-50% by weight of unmodified NaY molecular sieve, 10-30% by weight of silica binder and 10-80% by weight of clay on a dry basis; (2) The catalyst microspheres A are brought into contact with a rare earth solution to carry out an ion exchange reaction. After filtration, washing and drying, catalyst microspheres B are obtained. (3) The catalyst microspheres B are subjected to mild hydrothermal ultrastability modification treatment and optionally dried to obtain catalyst microspheres C; The mild hydrothermal ultrastability modification treatment involves calcining the catalyst microspheres B at a temperature of 350–450°C in an atmosphere containing 40–60% by volume water vapor for 4–6 hours; wherein the water content of the catalyst microspheres C does not exceed 1% by weight. (4) The catalyst microspheres C are brought into contact with SiCl4 gas and reacted, washed, and filtered to obtain catalyst D; the catalyst microspheres C are brought into contact with SiCl4 gas at a temperature of 250 to 450°C, wherein the weight ratio of SiCl4 to catalyst microspheres C on a dry basis is 0.03 to 0.2:1, and the reaction time is 10 minutes to 5 hours. (5) The catalyst microspheres D are treated with inorganic acid and organic acid, and after filtration, washing and drying, catalyst microspheres E are obtained; (6) Contact the catalyst microspheres E with an exchange liquid containing phosphorus compounds, filter and wash to obtain catalyst microspheres F; (7) Contact the catalyst microspheres F with a solution containing the active element, dry and calcine; the active element is gallium and / or boron.

5. The method for preparing the catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4, characterized in that, The unmodified NaY molecular sieve mentioned in step (1) is a hydrothermally synthesized NaY molecular sieve that has only been washed with water and the pH of the filter cake of the NaY molecular sieve after washing is measured to be 7-9. The calcination temperature mentioned in step (1) is 300-350℃ and the time is 1-4 hours.

6. The method for preparing the catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4, characterized in that, The rare earth ion exchange modification in step (2) is carried out at a temperature of 20-60°C and an exchange time of 90-120 minutes. The rare earth salt solution is an aqueous solution of rare earth salts. The rare earth salts are rare earth chlorides and / or rare earth nitrates.

7. The method for preparing the catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4, characterized in that, The mild hydrothermal ultra-stable modification treatment described in step (3) is carried out at a temperature of 370-420°C, in an atmosphere containing 45-55% water vapor by volume, and for 5-6 hours.

8. The method for preparing the catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4, characterized in that, In step (4), the temperature at which the catalyst microspheres C react with SiCl4 gas is 280–420°C and the reaction time is 0.5–2 hours.

9. The method for preparing the catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4 or 8, characterized in that, In step (4), the catalyst microspheres C react with SiCl4 gas, and the weight ratio of SiCl4 to catalyst microspheres C is 0.05 to 0.15:

1.

10. The method for preparing the catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4, characterized in that, In step (5), the catalyst microspheres D are treated with inorganic and organic acids, which includes contacting the catalyst microspheres D with inorganic and organic acid solutions at temperatures of 40–80°C for at least 60 minutes.

11. The method for preparing the catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 10, characterized in that, In step (5), the catalyst microspheres D obtained in step (4) are first mixed with an inorganic acid of medium strength or higher and water, and contacted at 40-80°C for at least 60 minutes. Then an organic acid is added, and contacted at 40-80°C for at least 60 minutes. After filtration, washing and drying, catalyst microspheres E are obtained. The proportions of catalyst microspheres D, inorganic acids of moderate to high strength, and water are as follows: the weight ratio of inorganic acids of moderate to high strength to catalyst microspheres D on a dry basis is 0.01–0.05:1; the weight ratio of water to catalyst microspheres D is 6–12:1; and the weight ratio of organic acids to catalyst microspheres D on a dry basis is 0.02–0.10:

1. The amount of inorganic acids of moderate to high strength is calculated as an inorganic acid solution, and the concentration of the inorganic acid solution is 5–15% by weight.

12. The method for preparing the low-coke, high-yield BTX-rich aromatic gasoline catalytic cracking catalyst according to claim 10 or 11, characterized in that, In step (5), the contact temperature is 50-60°C and the contact time is 60-120 minutes.

13. The method for preparing the catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 11, characterized in that, The concentration of the inorganic acid solution is 10% by weight.

14. The method for preparing a catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4, characterized in that, In step (6), the catalyst microspheres E are subjected to an exchange reaction with an exchange liquid containing phosphorus compounds at 15–100°C for more than 10 minutes, followed by filtration and washing; the phosphorus compounds are one or more of ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

15. The method for preparing a catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4, characterized in that, In step (6), the exchange reaction takes 10 to 100 minutes.

16. The method for preparing the catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4, characterized in that, The organic acid is one or more of malic acid, salicylic acid, tartaric acid, citric acid, oxalic acid, malonic acid, succinic acid, and methylsuccinic acid; the inorganic acid is one or more of nitric acid, hydrochloric acid, sulfuric acid, and phosphoric acid; the solution containing the active element contains gallium salt solution and / or boron compound solution, wherein the gallium salt is one or more of gallium sulfate, nitrate, and chloride, and the boron compound is boric acid, borate, metaborate, or polyborate, or a combination of two, three, or four of them.

17. The method for preparing a catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4 or 16, characterized in that, The active element is boron. The method of contacting the catalyst microspheres F with the solution containing the active element in step (7) includes: heating the catalyst microspheres E to 60-99°C and then contacting them with boron compounds in an aqueous solution at 60-99°C for 1-2 hours, wherein the weight ratio of boron (calculated as B2O3), water, and catalyst microspheres F (calculated on a dry basis) is (0.0015-0.015):(2.5-5):1; or, The active element is gallium. The method of contacting the catalyst microsphere F with the solution containing the active element in step (7) includes: mixing the catalyst microsphere F with an aqueous solution of gallium salt uniformly, and letting it stand at 15-40°C for 24-36 hours. The weight ratio of gallium in the aqueous solution of gallium salt (calculated as Ga2O3), water in the aqueous solution of gallium salt, and catalyst microsphere F on a dry basis is (0.0004-0.01):(2-3):

1. or, The active elements are boron and gallium. The method of contacting the catalyst microspheres F with the solution containing the active elements in step (7) includes: heating the catalyst microspheres F to 80-95°C and then contacting them with a boron compound in a first aqueous solution at 80-95°C for 1-2 hours. The weight ratio of boron, water, and catalyst microspheres F in the first aqueous solution (based on B2O3) is (0.0015-0.01):(2.5-5):1 on a dry basis. The mixture is filtered, and then the obtained catalyst material is mixed evenly with a second aqueous solution containing gallium salt and allowed to stand at 15-40°C for 24-36 hours. The weight ratio of gallium, water, and catalyst microspheres F in the second aqueous solution (based on Ga2O3) is (0.0004-0.007):(2-3):1 on a dry basis.

18. The method for preparing a catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4, characterized in that, The catalyst microspheres A contain: 20-55% by weight of clay on a dry basis, 20-50% by weight of unmodified NaY molecular sieve on a dry basis, 3-5% by weight of alumina sol on alumina, and 10-25% by weight of silica sol on silica.

19. The method for preparing a catalytic cracking catalyst with low coke production and high yield of BTX-rich aromatic gasoline according to claim 4 or 18, characterized in that, The catalytic cracking catalyst for low coke production and high yield of BTX aromatic gasoline contains 1-4% rare earth elements as RE2O3, 0.3-2% phosphorus as P2O5, and 0.1-1% active elements as oxides, of which boron is calculated as B2O3, gallium as Ga2O3, and sodium oxide content not exceeding 0.15% by weight.

20. A method for converting hydrogenated LCO, comprising the step of contacting and reacting hydrogenated LCO with a catalytic cracking catalyst of low-coke, high-yield BTX-rich aromatic gasoline as described in any one of claims 1 to 3, or a catalytic cracking catalyst of low-coke, high-yield BTX-rich aromatic gasoline prepared according to any one of claims 4 to 19.

21. The method according to claim 4 or 14, wherein, The reaction temperature is 480–520℃, the reaction time is 1–5 seconds, and the agent-to-oil ratio is 3–10 by weight.

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