A catalytic cracking catalyst and a method for preparing the same

Abstract

The application provides a catalytic cracking catalyst and a preparation method thereof. The catalytic cracking catalyst comprises, taking the weight of the catalytic cracking catalyst as 100%, 15-50% of rare earth ultra-stable Y type molecular sieve in dry basis, 10-60% of clay in dry basis, 1-4% of yttrium in oxide basis and 5-35% of binder in oxide basis; wherein the content of the rare earth in the rare earth ultra-stable Y type molecular sieve is not more than 3% in oxide basis, taking the weight of the catalytic cracking catalyst as 100%. The catalyst utilizes the characteristics of small cell and more mesopores of the low-content rare earth ultra-stable Y type molecular sieve, and yttrium is additionally added on the basis of the low-content rare earth ultra-stable Y type molecular sieve, so that the activity stability of the catalyst is better, the mass transfer, cracking reaction and selective hydrogen transfer reaction process are promoted, the selectivity of the catalytic cracking reaction is improved, and the coke formation is reduced while the content of olefin in gasoline is reduced.

Description

Technical Field

[0001] This invention belongs to the field of refining catalysts, and relates to a catalytic cracking catalyst, particularly a catalytic cracking catalyst for reducing the olefin content of gasoline and its preparation method. Background Technology

[0002] Environmental regulations strictly limit the olefin content of commercial gasoline. The National VI standard for automotive gasoline requires that the olefin content of gasoline not exceed 18% by volume. In my country, catalytic cracking gasoline accounts for more than 50% of the gasoline blending components, so the olefin content of catalytic cracking gasoline has a great impact on the olefin content of gasoline blended in the refinery's gasoline pool. The olefin content of catalytic cracking gasoline is relatively high, which affects the burden of subsequent gasoline hydrotreating. At present, the ways to reduce the olefin content of gasoline include: (1) Hydrotreating catalytic cracking gasoline. This method can effectively reduce the olefin content of gasoline, but it consumes hydrogen, increases the cost and burden of gasoline treatment, and reduces the octane number of gasoline; (2) Through specific process technologies, such as using dual risers or auxiliary risers, catalytic gasoline is recycled and upgraded. This process requires modification of conventional catalytic cracking units, increases equipment investment, changes the product distribution of the unit, and limits the operational stability; (3) In the catalytic cracking process, catalysts or additives are used to reduce the olefin content of gasoline without increasing equipment investment. This is a flexible and convenient way to reduce the olefin content of gasoline.

[0003] In the research and development of olefin-reducing catalysts and additives, Chinese patent CN1322928C discloses a cracking catalyst for reducing the olefin content of catalytic cracking gasoline. The catalyst contains 10–50 wt% CDY molecular sieve, prepared via a liquid-solid combined exchange process. The rare earth content, calculated as rare earth oxides, is 12–22 wt%, with all rare earth ions located within the molecular sieve cages. Its 27Al MAS NMR spectrum shows no peak at a chemical shift of 0 ppm. This catalyst can significantly reduce the olefin content of catalytic cracking gasoline while exhibiting strong heavy oil conversion capability.

[0004] Chinese patent CN101081369B discloses a rare-earth-containing high-silicon Y-type zeolite and its preparation method. The zeolite has a silicon-to-aluminum ratio of 5–30, an initial cell constant of 2.430–2.460 nm, a rare-earth content of 10–20 wt%, and a ratio of equilibrium cell constant to initial cell constant of at least 0.985. X-ray diffraction analysis shows that the intensity ratio I1 / I2 of the two diffraction peaks at 2θ of (12.43±0.06)° and (11.87±0.06)° is greater than 1. This zeolite is prepared by a gas-phase ultrastable method followed by rare-earth ion exchange, resulting in a more optimized zeolite structure and improved thermal stability, hydrothermal stability, cracking activity, and olefin-reducing performance.

[0005] Chinese patent CN1230496C discloses a petroleum hydrocarbon cracking catalyst containing rare earth Y-type zeolite and its preparation method. The catalyst is characterized in that the rare earth Y-type zeolite, calculated as RE2O3, has an intracrystalline rare earth content of 4-15 wt%, a cell constant of 2.450-2.458 nm, and a differential thermal collapse temperature of 1000-1056℃. The catalyst is prepared by drying the rare earth Y-type zeolite to reduce its water content to less than 10 wt%, then reacting it with silicon tetrachloride gas carried by dry air at a weight ratio of silicon tetrachloride:Y-type zeolite of 0.1-0.9:1. After purging with dry air and washing with decationized water to remove soluble byproducts, the above-mentioned rare earth Y-type zeolite is obtained. It is then mixed with raw materials including rare earth and binder, slurried, and spray-dried to form the catalyst. Compared with existing heavy oil olefin reduction catalysts, this catalyst can reduce the amount of zeolite by 5-25% by weight. It has the characteristics of good activity, high hydrothermal stability, strong heavy oil conversion ability, and good selectivity for gasoline, dry gas, and coke, and can reduce the olefin content of catalytic cracking gasoline.

[0006] Chinese patent CN1278773C discloses a catalyst for reducing the olefin content of gasoline and its preparation method. The catalyst consists of a molecular sieve active component, amorphous silica-alumina oxide, and kaolin. The active component comprises 0.5–10% (by weight of the catalyst) of rare earth-ZSM-5 / ZSM-11 co-crystallized molecular sieve and 15–40% (by weight of the catalyst) of rare earth Y molecular sieve. The composite molecular sieve is uniformly mixed with alumina and kaolin, then spray-formed, dried, and steam-treated to obtain the catalyst. This catalyst has the characteristics of reducing the olefin content of gasoline while maintaining the gasoline octane number at least without decreasing.

[0007] Chinese patent CN1247744C discloses a high-yield diesel-producing olefin-reducing cracking catalyst and its preparation method. The catalyst contains 5-45 wt% phosphorus and rare earth composite modified Y zeolite (or ultra-stable rare earth Y zeolite). This ultra-stable rare earth Y zeolite is obtained by using sodium Y zeolite as raw material, undergoing rare earth exchange and a first calcination, followed by reaction with rare earth, phosphorus-containing substances, and ammonium salts, and then a second calcination. The catalyst composition consists of 5-45 wt% ultra-stable rare earth Y zeolite, 0.5-30 wt% one or more other zeolites, 0.5-70 wt% clay, and 1.0-65 ​​wt% high-temperature resistant inorganic oxides, containing 0.3-2.5 wt% phosphorus and 1.5-6.0 wt% rare earth oxides. The catalyst preparation method involves mixing the above zeolite components, clay, and high-temperature resistant inorganic oxide precursors in a specific ratio, homogenizing, spraying, and post-treatment to obtain the finished catalyst. This catalyst has a strong ability to reduce olefins and a high diesel yield, while having a low coke yield and a strong ability to crack heavy oil.

[0008] Chinese patent CN100395029C discloses a method for preparing a cracking catalyst that reduces gasoline olefin content and increases liquefied petroleum gas (LPG) production. The method involves uniformly mixing clay, deionized water, and a phosphorus-containing compound to obtain a clay slurry; uniformly mixing molecular sieves, deionized water, a phosphorus-containing compound, and a rare earth compound to obtain a molecular sieve slurry; and uniformly mixing a binder, deionized water, and an optional inorganic acid to obtain a binder slurry. The clay slurry, molecular sieve slurry, and binder slurry are then uniformly mixed and dried. The catalyst exhibits a high LPG yield, particularly a high propylene concentration in the LPG, while maintaining a high gasoline yield and gasoline octane number, and reducing the gasoline olefin content.

[0009] Chinese patent CN1100849C discloses a catalytic cracking catalyst and its preparation method. The catalyst comprises 1-54 wt% Y-type molecular sieve, 1-20 wt% ZSM-5 molecular sieve, 35-60 wt% support, and 10-25 wt% binder. The Y-type molecular sieve is REY, REHY, USY, or REUSY. The ZSM-5 molecular sieve is a hydrogen-type molecular sieve modified with two or more elements selected from zinc, gallium, and rare earth elements. The support is SiO2, Al2O3, MgO, ZrO2, kaolin, diatomaceous earth, sepiolite, aluminum-magnesium spinel, or a mixture thereof. The modifying element used in the support is zinc, phosphorus, rare earth elements, or a mixture thereof, and the content of the modifying element in the support is 0.01-25 wt%. This catalyst can reduce the olefin content of gasoline while increasing the octane number of gasoline.

[0010] Chinese patent CN1309472C discloses a catalytic cracking catalyst and its preparation method. The catalyst consists of 60-87 wt% kaolin, 10-30 wt% metal-modified Y-type molecular sieve, and 3-10 wt% binder, based on the total weight of the catalyst. The modifying element used in the metal-modified Y-type molecular sieve is one or more of copper, iron, zinc, cobalt, titanium, nickel, antimony, vanadium, manganese, and molybdenum. The modified metal content in the Y-type molecular sieve is 4-30% (based on the weight percentage of the modified metal oxide in the modified Y-type molecular sieve). Gasoline produced using this catalyst exhibits a 50-70 wt% reduction in sulfur content, a 20-40 vol percentage point reduction in olefin content, and an increase in octane number of 0.3-2.0 units.

[0011] Chinese patent CN103084199 B discloses an alkali- and nitrogen-resistant olefin-reducing cracking catalyst and its preparation method. The catalyst comprises a cracking active component, a mesoporous silica-alumina material, a binder, and clay. The cracking active component includes a first Y-type molecular sieve and a second Y-type molecular sieve. The first Y-type molecular sieve contains 8-23% by weight of rare earth elements (based on rare earth oxides), 0.1-3.0% by weight of iron (based on Fe2O3), 0-3.0% by weight of copper (based on CuO), 0-2.0% by weight of phosphorus (based on P2O5), and 0.1-2.5% by weight of sodium oxide. The second Y-type molecular sieve is a phosphorus- and rare earth-modified Y-type molecular sieve. The catalyst preparation method includes preparing a slurry containing the cracking active component, mesoporous silica-alumina material, binder, and clay, spray drying, washing, and drying. This catalyst is used for the catalytic cracking of hydrocarbon oils with high alkali and nitrogen content, exhibiting higher conversion rates and lower gasoline olefin content.

[0012] Chinese patent CN 1332758C discloses a phosphorus-containing and amorphous silica REY molecular sieve, its preparation method, and its application. 31 In the PMAS NMR spectrum, the sum of the peak areas of the peaks with chemical shifts of -15±2ppm and -23±2ppm accounts for more than 85% of the total peak area. The molecular sieve contains 12–20 wt% rare earth elements (RE2O3), 1–4 wt% phosphorus (P2O5), and 5–10 wt% amorphous silica (SiO2). This molecular sieve has the effect of reducing the olefin content of gasoline and has good coke selectivity, and can be used as an active component of catalytic cracking catalysts.

[0013] Chinese patent CN 107973315 B discloses a phosphorus- and rare earth-containing Y-type molecular sieve and its preparation method. The molecular sieve has a cell parameter of 24.35-24.55 Å; a phosphorus content of 0.3-10 wt%; a rare earth content of 0.5-19 wt%; an Al distribution parameter D satisfying 0.4 ≤ D ≤ 0.9; a mesopore volume accounting for 25-65% of the total pore volume; a strong acid content accounting for 20-60% of the total acid content; and a Brønsted acid to Lewis acid ratio of 20-100. Catalysts prepared using this molecular sieve as the active component exhibit excellent heavy oil conversion capacity, higher gasoline and LPG yields, lower coke yield, and lower gasoline olefin content in heavy oil cracking reactions. The molecular sieve is prepared by dealuminization and silicon replenishment with silicon tetrachloride gas, dealuminization with an acid solution composed of organic and inorganic acids, inorganic alkali treatment, and dealuminization with a composite acid such as fluorosilicic acid. The preparation process is complex, difficult to operate, and causes environmental pollution.

[0014] Chinese Patent CN 102812109 B discloses a high-light-olefins FCC catalyst composition and a method for cracking hydrocarbons to maximize the production of light olefins. The catalyst composition comprises at least one zeolite, preferably a Y-type zeolite, exhibiting catalytic cracking activity under catalytic cracking conditions, wherein the zeolite has a small amount of yttrium exchanged on it in a specific ratio with a rare earth metal. The amount of yttrium exchanged on the zeolite is from 1.75% to 0.175% by weight of the zeolite, and the weight ratio of yttrium exchanged on the zeolite to the rare earth metal is from 3 to 50. Compared to conventional lanthanum-containing Y-type zeolite FCC catalysts, the catalyst and method of this invention provide increased light olefin yields and gasoline olefin yields during the FCC process.

[0015] Chinese patent CN 101104817 B discloses a catalytic cracking additive for improving heavy oil conversion and its preparation method. The additive uses one or a mixture of natural sepiolite and natural kaolinite or roasted kaolinite as raw materials, and is prepared through spray molding, roasting, in-situ crystallization, and composite element modification. The additive contains 20-90% NaY molecular sieve with a SiO2 / Al2O3 molar ratio of 4.0-6.0, 1.0-20% rare earth oxides, 25-50% Al2O3, 1.0-20% MgO, and less than 0.5% sodium oxide, with a specific surface area ≥300 μm. 2 / g, pore volume ≥0.25ml / g. This additive can improve heavy oil conversion capacity, has high activity, strong resistance to heavy metal pollution, and good selectivity in cracking reactions. At the same time, it can also reduce the olefin content of gasoline and increase the octane number of gasoline.

[0016] Chinese patent CN 1151237 C discloses a catalytic cracking additive for reducing the olefin content of gasoline. It is composed of rare-earth-containing Y-type zeolite, rare-earth-containing MFI structural zeolite, clay, alumina, and phosphorus. The ratio of rare-earth content in the rare-earth-containing Y-type zeolite to that in the MFI structural zeolite is 0.05–200:1. The additive is prepared by uniformly mixing a matrix synthesized from rare-earth-containing Y-type zeolite treated with a phosphorus-containing compound solution, MFI structural zeolite treated with a rare-earth solution, and clay with a double-aluminum binder, followed by spray drying, post-treatment with a phosphorus-containing compound solution, filtration, and drying. This additive can reduce the olefin content in gasoline produced by catalytic cracking by 5–9 percentage points.

[0017] Chinese patent CN 1156555C discloses a catalytic cracking additive and its preparation method. The additive consists of 5-65 wt% ZSM-5 molecular sieve, 15-60 wt% support, and 10-40 wt% binder. The ZSM-5 molecular sieve is in its hydrogen form and modified with phosphorus, zinc, and at least one rare earth element. The additive is prepared by first modifying the hydrogen-form ZSM-5 molecular sieve with Zn and rare earth elements. The modified ZSM-5 molecular sieve and support are then added to an aluminum phosphate sol binder, mixed, slurried, and homogenized. The mixture is then filtered, spray-dried, and calcined. Under conventional catalytic cracking conditions, when the additive accounts for 1-15% of the total weight of the catalytic cracking catalyst, it can reduce the olefin content in catalytic cracked gasoline by 3-25 percentage points and increase the gasoline's research octane number by 0.5-3 units.

[0018] Chinese patent CN1201864C discloses an FCC catalyst for reducing the olefin content of gasoline and its preparation method. The catalyst is composed of a zeolite-type active component, amorphous silica-alumina oxide, and kaolin. The active component consists of 0.5–5 wt% ZSM-5, 0.5–15 wt% rare earth Y zeolite, and 20–40 wt% phosphorus and rare earth composite modified ultrastable Y zeolite. The composite molecular sieve is uniformly mixed with alumina, binder, and kaolin, and then spray-dried, cured, washed, and dried to obtain the FCC catalyst. Compared with conventional catalysts, this catalyst can significantly reduce the olefin content of gasoline while maintaining the product distribution and gasoline octane number essentially unchanged. However, this patent uses rare earth Y zeolite. Due to the high rare earth content and strong hydrogen transfer capacity of rare earth Y zeolite, it can effectively reduce the olefin content in gasoline, but the catalytic cracking coke yield is high. In addition, in order to improve coke selectivity, phosphorus and rare earth composite modification of ultrastable Y zeolite is used. However, phosphides can cause environmental pollution problems and are currently restricted in industrial production.

[0019] Chinese patent CN1191124C discloses a cracking catalyst for paraffin-based feedstock oil, composed of Y-type molecular sieves, MFI-structured molecular sieves, and β-molecular sieves, as well as clay, alumina, and phosphorus, wherein the amount of precipitated rare earth elements (RE2O3) is 0.05–12 wt%. This catalyst is obtained by treating a Y-type molecular sieve treated with rare earth hydroxide solution and a molecular sieve with an MFI structure with a phosphorus-containing compound solution, drying, calcining, mixing with alumina sol and / or boehmite and clay, homogenizing, calcining at 500°C or spray drying, and then post-treating with a phosphorus-containing compound solution. This catalyst can reduce the olefin content of gasoline while maintaining the RON octane number. However, this patent uses a rare earth hydroxide solution to treat the Y-type molecular sieve, wherein the amount of precipitated rare earth elements (RE2O3) is 0.05–12 wt%. If the rare earth content in the molecular sieve is low, the reduction in olefin content in gasoline is not significant. Conversely, if the rare earth content is high, it is beneficial for reducing olefin content in gasoline, but also results in strong hydrogen transfer capacity and high coke yield from catalytic cracking. Furthermore, to improve coke selectivity, phosphide treatment is used on the molecular sieve or catalyst. However, phosphides cause environmental pollution and their use is currently restricted in industrial production.

[0020] In existing technologies, the design of olefin-reducing catalysts enhances hydrogen transfer reaction capabilities, promoting olefin saturation or converting light olefin components of gasoline into liquefied petroleum gas (LPG) through cracking. However, continuous hydrogen transfer increases the yield of coke from catalytic cracking, reduces the selectivity of the catalytic cracking reaction, and the increase in LPG yield is limited by the compressors in refinery units. Existing technologies use phosphorus-modified molecular sieves or catalysts and additives, but phosphorus causes environmental pollution and is restricted in industrial production. Existing technologies use dehydrogenation elements such as copper, iron, and zinc, or zinc-aluminum spinel materials, which increases the amount of raw coke. Using silicon tetrachloride to improve the activity and stability of molecular sieves requires high production conditions, with strict limitations on the airtightness of the unit and the water content during molecular sieve treatment, making operation difficult. Existing technologies use high rare earth content to increase the hydrogen transfer activity of catalysts and additives, which does reduce the olefin content in gasoline, but increases the yield of coke from catalytic cracking. To improve reaction selectivity, existing technologies employ methods such as acid-base treatment of molecular sieves to remove aluminum and silicon, forming mesopores within the sieves. However, this approach is clearly unsuitable for industrial production processes, and the cost of molecular sieve treatment is also high. In summary, while existing technologies meet the requirements for olefin reduction in catalytic cracking gasoline, they inevitably lead to problems such as decreased selectivity in the catalytic cracking reaction, increased coke yield, environmental pollution, and increased production complexity or manufacturing costs. Therefore, to meet the requirements of olefin reduction in catalytic cracking gasoline while maintaining good catalytic cracking reaction selectivity, despite recent advancements in catalyst and additive preparation technologies, further research is needed on catalysts that are environmentally friendly, simple, feasible, and possess excellent activity, hydrothermal stability, and good cracking reaction selectivity. Summary of the Invention

[0021] This invention provides a catalytic cracking catalyst and its preparation method, overcoming the problem that existing catalytic cracking catalysts are difficult to balance in terms of activity selectivity and catalyst stability.

[0022] To achieve the above objectives, the present invention provides a catalytic cracking catalyst, which, based on 100% by weight, comprises: 15-50% on a dry basis rare earth ultrastable Y-type molecular sieve, 10-60% on a dry basis clay, 1-4% on a basis of oxides of yttrium, and 5-35% on a basis of oxides of binder.

[0023] The rare earth content in the rare earth ultrastable Y-type molecular sieve is no more than 3%, calculated as oxides and based on the weight of the rare earth ultrastable Y-type molecular sieve as 100%.

[0024] The catalytic cracking catalyst of the present invention further includes lanthanide rare earth elements, wherein the weight content of the lanthanide rare earth elements in the catalytic cracking catalyst is 0.001-3% based on oxides.

[0025] The catalytic cracking catalyst of the present invention further includes other molecular sieves, wherein the weight content of the other molecular sieves in the catalytic cracking catalyst is 0.001-15% on a dry basis; the other molecular sieves are MFI shape-selective molecular sieves and / or USY molecular sieves.

[0026] The catalytic cracking catalyst of the present invention further includes magnesium and / or an inorganic oxide support material; the magnesium is calculated as oxide, the inorganic oxide support material is calculated as oxide, the magnesium content in the catalytic cracking catalyst is 0-3%, and the inorganic oxide support material content is 0-30%.

[0027] The catalytic cracking catalyst of the present invention has an average particle size of 48-70 μm and a cell constant of 2.440-2.460 nm for the rare earth ultrastable Y-type molecular sieve.

[0028] The catalytic cracking catalyst of the present invention contains a rare earth content of 0.5-3 wt% in the rare earth ultrastable Y-type molecular sieve, wherein the rare earth is at least one of yttrium and lanthanide rare earths.

[0029] The catalytic cracking catalyst of the present invention comprises, wherein the clay is selected from at least one of kaolin, hydrous kaolin, montmorillonite, diatomaceous earth, sepiolite, and bentonite; and the binder is selected from at least one of boehmite, alumina sol, silica sol, and aluminosilicate.

[0030] The catalytic cracking catalyst of the present invention, wherein the inorganic oxide support material is selected from at least one of silica, alumina containing Brønsted acid centers, and aluminosilicate containing Brønsted acid centers.

[0031] To achieve the above objectives, the present invention also provides a method for preparing the above-mentioned catalytic cracking catalyst, comprising the following steps:

[0032] Rare earth ultrastable Y-type molecular sieve, clay, yttrium-containing compound and binder are mixed and slurried, then the slurry is spray-formed, dried, cured and washed with water to prepare a catalytic cracking catalyst.

[0033] The method for preparing the catalytic cracking catalyst of the present invention comprises: first mixing and stirring a rare earth ultrastable Y-type molecular sieve with a yttrium-containing compound, then mixing and stirring it with clay and a binder to form a slurry; spraying the slurry into shape, drying, curing, and washing with water to obtain the catalytic cracking catalyst; wherein the yttrium-containing compound is selected from at least one of yttrium halides, yttrium nitrates, yttrium carbonates, yttrium oxides, and yttrium hydroxides.

[0034] The method for preparing the catalytic cracking catalyst of the present invention further includes the addition of lanthanide rare earth compounds to the slurry. The lanthanide rare earth compounds are selected from at least one of lanthanide rare earth halides, lanthanide rare earth nitrates, lanthanide rare earth carbonates, lanthanide rare earth oxides, and lanthanide rare earth hydroxides.

[0035] The beneficial effects of this invention are:

[0036] The catalyst of this invention utilizes the characteristics of low-rare-earth ultrastable Y molecular sieves, such as small cell size and numerous mesopores. Based on the low-rare-earth ultrastable Y molecular sieve, yttrium is added to further enhance the catalyst's activity and stability, which is beneficial for promoting mass transfer, cracking reaction, and selective hydrogen transfer reaction processes. This reduces the olefin content in gasoline while improving the selectivity of catalytic cracking reaction and reducing coking. Attached Figure Description

[0037] Figure 1 The BJH pore distribution curves of the silicon-aluminum material APM-7 and industrial pseudoboehmite in Example 5 are shown. Detailed Implementation

[0038] The following provides a detailed description of the embodiments of the present invention. These embodiments are implemented based on the technical solution of the present invention and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0039] The present invention provides a catalytic cracking catalyst, which, based on 100% by weight, comprises: 15-50% on a dry basis rare earth ultrastable Y-type molecular sieve, 10-60% on a dry basis clay, 1-4% on a basis of oxides of yttrium, and 5-35% on a basis of oxides of binder.

[0040] The rare earth content in the rare earth ultrastable Y-type molecular sieve is no more than 3%, calculated as oxides and based on the weight of the rare earth ultrastable Y-type molecular sieve as 100%.

[0041] The rare earth content of the rare earth ultrastable Y-type molecular sieve in the catalytic cracking catalyst of this invention is low, with the rare earth content accounting for no more than 3% of the mass of the rare earth ultrastable Y-type molecular sieve. At the same time, the catalyst is also mixed with additional yttrium rare earth. This can avoid the problem of the catalyst being prone to coking due to the excessive hydrogen transfer capacity of the ultrastable Y-type molecular sieve with high rare earth content, and can also ensure that the olefin content in the gasoline produced by heavy oil catalytic cracking is low.

[0042] In detail, the rare earth portion of the catalyst in this invention is loaded onto a rare earth ultra-stable Y-type molecular sieve, and part of it is added through a mixing method. The rare earth added through mixing with other raw materials of the catalyst has the function of capturing heavy metals such as nickel and vanadium during the use of the catalyst, avoiding heavy metal contamination of the catalyst in the feed oil, which would cause a decrease in catalyst activity and selectivity. In addition, during the use of the catalyst, this rare earth portion can also partially migrate into the crystal structure of the Y-type molecular sieve through solid-phase migration, playing the same role as ion-exchange rare earth, that is, improving catalyst activity and stabilizing the molecular sieve structure.

[0043] In one embodiment, the rare earth content of the rare earth ultrastable Y-type molecular sieve of the present invention is 0.5-3 wt% (based on rare earth oxides, calculated as 100% by weight of the rare earth ultrastable Y-type molecular sieve), preferably 1-2 wt%. The rare earth elements in the rare earth ultrastable Y-type molecular sieve are selected from one or more of yttrium and lanthanide rare earths. The present invention does not particularly limit the preparation method of the rare earth ultrastable Y-type molecular sieve. In one embodiment, the rare earth ultrastable Y-type molecular sieve can be prepared by ion exchange and hydrothermal ultrastable methods. Compared with ultrastable Y-type molecular sieves with high rare earth content, low-content rare earth ultrastable Y-type molecular sieves are more prone to forming more mesopores, which is beneficial to the mass transfer process between reactant oil molecules and product molecules, and reduces coking.

[0044] This invention does not impose any particular limitation on the type of clay in the catalyst; any clay conventionally used in catalytic cracking catalysts in the art is acceptable. For example, it may be one or more of kaolin, hydrous kaolin, montmorillonite, diatomaceous earth, sepiolite, and bentonite, with kaolin or hydrous kaolin being preferred.

[0045] This invention does not impose any particular limitation on the type of binder in the catalyst; any binder conventionally used in catalytic cracking catalysts in the art is acceptable. For example, it may be one or more of boehmite, alumina sol, silica sol, and aluminosilicate, with boehmite and alumina sol being preferred.

[0046] In addition to the rare earth ultra-stable Y-type molecular sieve, the catalytic cracking catalyst of this invention also contains yttrium, which ensures that the gasoline obtained when the catalytic cracking catalyst is used for catalytic cracking of feedstock oil has a low olefin content.

[0047] In one embodiment, the rare-earth ultrastable Y-type molecular sieve of the present invention has a cell constant of 2.440–2.460 nm, and the average particle size of the catalytic cracking catalyst is 48–70 μm. The relatively small cell constant of the rare-earth ultrastable Y-type molecular sieve of the present invention results in a greater number of mesopores, which is beneficial for the mass transfer process between reactant and product molecules, reducing coking. Furthermore, the lower average particle size of the catalytic cracking catalyst of the present invention facilitates the mass transfer process between reactant and product molecules within the catalyst, reducing adverse side reactions caused by prolonged residence of hydrocarbon molecules in the catalyst. Moreover, the increased total surface area and outer surface area of ​​the catalyst provide more active centers for the reaction, thereby improving the selectivity of the catalytic cracking reaction while enhancing the olefin-reducing capacity.

[0048] In one embodiment, the catalytic cracking catalyst of the present invention further includes lanthanide rare earth elements, wherein the weight content of the lanthanide rare earth elements in the catalytic cracking catalyst is 0.001-3% based on oxides. In the present invention, the lanthanide rare earth elements mainly exist in the catalytic cracking catalyst in oxide form, for example, in oxide form that is easily formed by calcination of lanthanide rare earth compounds.

[0049] In one embodiment, the catalytic cracking catalyst further includes other molecular sieves, the weight content of which, on a dry basis, is 0.001–15%. In another embodiment, the other molecular sieves are MFI shape-selective molecular sieves and / or USY molecular sieves. In yet another embodiment, the other molecular sieves include 0–10 wt% MFI shape-selective molecular sieves on a dry basis and 0–5 wt% USY molecular sieves on a dry basis (based on 100% of the total weight of the catalytic cracking catalyst).

[0050] In one embodiment, the catalytic cracking catalyst of the present invention further includes an inorganic oxide support material; the inorganic oxide support material is calculated as oxide, and the content of the inorganic oxide support material in the catalytic cracking catalyst is 0-30%, more specifically 0.001-30%.

[0051] The inorganic oxide carrier material is selected from one or more of the following: silica, alumina containing Brønsted acid centers, and aluminosilicate containing Brønsted acid centers. Alumina and aluminosilicate containing Brønsted acid centers possess high pore volume, large specific surface area, dual-pore distribution, high thermal stability, and high acidity, and also contain Brønsted acid centers.

[0052] This invention employs one or more oxide support materials selected from silica, alumina containing Brønsted acid centers, and aluminosilicate materials containing Brønsted acid centers. These materials improve the pore structure of the catalyst, facilitating mass transfer between reactants and products. This reduces the olefin content in gasoline while preventing excessive hydrogen transfer and minimizing side reactions. Furthermore, the alumina and aluminosilicate materials containing Brønsted acid centers have higher acid content and contain Brønsted acid centers, improving heavy oil conversion performance. This facilitates the conversion of low-olefin-content heavy oil and diesel into the gasoline fraction, diluting the olefins in the gasoline fraction and resulting in a higher total liquid yield (LPG + gasoline + diesel) from the catalytic cracking reaction.

[0053] In one embodiment, the catalytic cracking catalyst of the present invention further includes magnesium; the magnesium content in the catalytic cracking catalyst is 0-3%, more specifically 0.001-3%, calculated as oxide. In the present invention, magnesium exists mainly in the form of oxides in the catalytic cracking catalyst, for example, in the form of oxides that are easily formed by calcination of magnesium-containing compounds.

[0054] In one specific embodiment, the catalytic cracking catalyst of the present invention, based on 100% catalyst weight, contains 15-50% (dry basis) of rare earth ultrastable Y-type molecular sieve (wherein, based on the mass of the rare earth ultrastable Y-type molecular sieve, the content of rare earth oxide in the molecular sieve is not greater than 3%), 0-15% (dry basis) of other molecular sieves, 10-60% (dry basis) of clay, 1-4% (oxide basis) of yttrium, 0-3% (oxide basis) of lanthanide rare earths, 0-3% (oxide basis) of magnesium, 0-30% (oxide basis) of inorganic oxide support material, and 5-35% (oxide basis) of binder.

[0055] In another specific embodiment, the preferred composition of the catalytic cracking catalyst of the present invention is as follows: based on 100% catalyst weight, it contains 15-40% rare earth ultrastable Y-type molecular sieve on a dry basis, 0-10% other molecular sieves on a dry basis, 20-60% clay on a dry basis, 1-3% yttrium on an oxide basis, 0-2% lanthanide rare earth on an oxide basis, 0-2% magnesium on an oxide basis, 2-15% inorganic oxide support material on an oxide basis, and 10-30% binder on an oxide basis; the average particle size of the catalyst is 52-70 μm, wherein the cell constant of the rare earth ultrastable Y-type molecular sieve is 2.440-2.460 nm.

[0056] The catalyst of this invention contains yttrium, lanthanide rare earth elements, magnesium, etc. These substances are beneficial to improving the activity and resistance to heavy metal pollution of the catalyst, and modulate the distribution of acid active centers in the catalyst, making it more conducive to improving the conversion rate of catalytic cracking reaction and reducing coke yield.

[0057] In one embodiment, the present invention also provides a method for preparing the above-mentioned catalytic cracking catalyst, comprising the following steps:

[0058] Rare earth ultrastable Y-type molecular sieve, clay, yttrium-containing compound and binder are mixed and slurried, then the slurry is spray-formed, dried, cured and washed with water to prepare a catalytic cracking catalyst.

[0059] In another embodiment, the method for preparing the catalytic cracking catalyst of the present invention includes the following steps:

[0060] Rare earth ultrastable Y-type molecular sieves are first mixed and stirred with yttrium-containing compounds, and then mixed with clay and binder to form a slurry. The slurry is then spray-formed, dried, cured, and washed with water to prepare a catalytic cracking catalyst.

[0061] The yttrium-containing compound is selected from at least one of yttrium halides, yttrium nitrates, yttrium carbonates, yttrium oxides, and yttrium hydroxides.

[0062] In one embodiment, a lanthanide rare earth compound is also added to the slurry. The lanthanide rare earth compound is selected from at least one of lanthanide rare earth halides, lanthanide rare earth nitrates, lanthanide rare earth carbonates, lanthanide rare earth oxides, and lanthanide rare earth hydroxides. In another embodiment, the lanthanide rare earth is lanthanum-rich rare earth, cerium-rich rare earth, pure lanthanum, or pure cerium.

[0063] In one embodiment, a magnesium-containing compound is also added to the slurry.

[0064] In one specific embodiment, the preparation method of the catalytic cracking catalyst of the present invention is as follows: rare earth ultrastable Y-type molecular sieves are first mixed with yttrium-containing compounds and stirred for 15-120 min. Then, they are mixed with clay, lanthanide rare earth compounds, inorganic oxide support materials, and binders to form a slurry. The slurry is then spray-dried, cured, and washed with water to obtain the catalyst. The pseudoboehmite is used after being dissolved in acid.

[0065] The adhesive needs to be dissolved in acid, which is an inorganic acid, such as hydrochloric acid, sulfuric acid, or nitric acid; then it is aged at 40–90°C for 0.5–3 hours.

[0066] The spray-forming and drying of the catalytic cracking catalyst of this invention is a technique well-known to those skilled in the art. The process conditions are as follows: the furnace temperature of the spray tower is controlled at 450–550°C, and the temperature of the spray exhaust gas is controlled at 200–300°C. This invention controls the sieving distribution of the spray-formed catalyst microspheres by controlling spray pressure, nozzle size, and other spray-forming conditions, resulting in a relatively small average particle size of the catalyst, maintained within the range of 48–70 μm.

[0067] Therefore, this invention provides a catalyst and its preparation method that differ from existing methods. By improving catalyst diffusion, selective hydrogen transfer reaction, and cracking reaction, it achieves selective conversion of gasoline olefins and reduces excessive coking reaction during catalytic cracking. The catalytic cracking catalyst provided by this invention has the characteristics of simple preparation process, small average particle size, high activity after 17h hydrothermal aging, low gasoline olefin content, low heavy oil yield, and good coke selectivity.

[0068] The catalytic cracking catalyst of this invention can be used alone or in combination with octane number additives as needed when applied to heavy oil catalytic cracking reactions. This invention is not particularly limited.

[0069] The technical solution of the present invention will be further described in detail below through specific embodiments. The inorganic oxide carrier material used in the following embodiments is a silicon-aluminum material containing Brønsted acid centers, specifically APM-7, produced by Lanzhou Petrochemical Company of China National Petroleum Corporation.

[0070] Table 1 lists the acidity data of APM-7 and industrial pseudoboehmite (comparative material). As shown in Table 1, the total L-acid and Brønsted acid content of APM-7 are 91.50 and 197.36 μmol / g, respectively, with a Brønsted / L-acid ratio as high as 2.2. In contrast, the comparative material contains only L-acid centers, with a total L-acid content of 213.61 μmol / g, which is lower than that of APM-7.

[0071] Table 1. Infrared acid characterization of APM-7 silicon-aluminum materials containing Brønsted acid centers.

[0072]

[0073] Figure 1 The image shows the BJH pore distribution curves of the silicon-aluminum material APM-7 and industrial pseudoboehmite from Example 5. Figure 1 As shown, APM-7 has both mesopores and macropores, while industrial pseudo-boehmite materials only have single-pore distributions in the 2-4 nm range, with pore diameters as small as 3.4 nm.

[0074] Example 1

[0075] 2.421 kg of kaolin (dry basis, industrial product of China Kaolin Company, the same below), 0.948 kg of alumina sol (containing 18.98 wt% Al2O3, produced by Lanzhou Petrochemical Company Catalyst Plant, the same below), 68.3 g of lanthanum chloride and 6.0 kg of deionized water were added to a pulping tank and pulped. Then 1.429 kg of boehmite (solid content 63.0 wt%, product of Shanxi Aluminum Plant, the same below) was added and stirred for 1 hour. Then 136 mL of concentrated hydrochloric acid was added and stirred for 1.5 hours. After that, the mixture was aged at 65°C for 2 hours.

[0076] 0.9 kg of REUSY molecular sieve (dry basis, Na2O content 1.1 wt%, RE2O3 content 2.0 wt%, silicon-to-aluminum ratio 5.1, produced by Lanzhou Petrochemical Company Catalyst Plant, the same below), 229 g of yttrium nitrate and 1.4 kg of deionized water were mixed and pulped for 1 hour, then added to the above pulping tank, pulped and homogenized, and spray dried under controlled conditions to obtain catalyst microspheres.

[0077] The catalyst microspheres obtained by spray drying were calcined, washed to remove sodium, and dried to obtain the cracking catalyst CAT-1 provided by the present invention.

[0078] The catalyst CAT-1 consisted of: 53.8 wt% kaolin, 20 wt% alumina from boehmite, 4.0 wt% alumina from alumina sol, 1.5 wt% yttrium oxide from yttrium nitrate, 0.7 wt% lanthanum oxide from lanthanum chloride, and 20 wt% REUSY-type molecular sieve. The particle size analysis results of CAT-1 are listed in Table 2.

[0079] Comparative Example 1

[0080] 1.956 kg of kaolin, 1.897 kg of aluminum sol, 68.3 g of lanthanum chloride and 4.43 kg of deionized water were added to a pulping tank and pulped. Then 1.429 kg of boehmite was added and stirred for 1 hour. Then 136 mL of concentrated hydrochloric acid was added and stirred for 1.5 hours. Finally, the mixture was aged at 65°C for 2 hours.

[0081] 1.575 kg of REHY molecular sieve (dry basis, Na2O content 1.1 wt%, RE2O3 content 8.0 wt%, produced by Lanzhou Petrochemical Company Catalyst Plant, the same below) and 2.49 kg of deionized water were mixed and pulped for 1 hour, then added to the above pulping tank, pulped and homogenized, and obtained catalyst microspheres under conventional spray drying conditions.

[0082] The catalyst microspheres obtained by spray drying were calcined, washed to remove sodium, and dried to obtain DCAT-1, a high rare earth content comparative cracking catalyst prepared under conventional spray drying conditions.

[0083] The composition of catalyst DCAT-1 is as follows: 36.3 wt% kaolin, 20 wt% alumina from boehmite, 8 wt% alumina from alumina sol, 0.7 wt% lanthanum oxide from lanthanum chloride, and 35 wt% REHY molecular sieve. The particle size analysis results of DCAT-1 are listed in Table 2.

[0084] Example 2

[0085] 3.102 kg of kaolin, 1.958 kg of aluminum sol and 3.1 kg of deionized water were added to a pulping tank and pulped. Then 0.746 kg of boehmite and 28 g of lanthanum oxide were added and stirred for 0.5 hours. Then 70 mL of concentrated hydrochloric acid was added and stirred for 2.0 hours. Finally, the mixture was aged at 70 °C for 1.5 hours.

[0086] 2.348 kg of REUSY molecular sieve, 99 g of yttrium chloride (calculated as oxide), 168 g of magnesium chloride and 2.56 kg of deionized water were mixed and pulped for 1.5 hours, then added to the above pulping tank and pulped and homogenized for 2 hours. The spray drying conditions were controlled to obtain catalyst microspheres.

[0087] The catalyst microspheres obtained by spray drying were calcined, washed to remove sodium, and dried to obtain the cracking catalyst CAT-2 provided by the present invention.

[0088] The composition of catalyst CAT-2 is as follows: 47.1 wt% kaolin, 8 wt% alumina from boehmite, 7 wt% alumina from alumina sol, 1.8 wt% yttrium oxide from yttrium chloride, 0.6 wt% magnesium oxide from magnesium chloride, 0.5 wt% lanthanum oxide, 35 wt% REUSY molecular sieve, and 38 wt% catalyst gel solids. The particle size analysis results of CAT-2 are listed in Table 2.

[0089] Example 3

[0090] 2.370 kg of kaolin (dry basis), 0.440 kg of alumina sol, 28 g of cerium oxide and 2.67 kg of deionized water were added to a pulping tank and pulped. Then 0.44 kg of boehmite (dry basis) was added and stirred for 1.0 hour. Then 40 mL of concentrated nitric acid was added and stirred for 1.0 hour. Finally, the mixture was aged at 50°C for 1.2 hours.

[0091] 1.76 kg (dry basis) of REUSY molecular sieve, 0.33 kg (dry basis) of high-silica ZSM-5 molecular sieve (from Lanzhou Petrochemical Company, with a silica-alumina ratio of over 300), 99 g of yttrium oxide, 33 g of magnesium oxide, and 2.84 kg of deionized water were mixed and pulped for 0.5 hours, then added to the above pulping tank and homogenized for 1.8 hours. The catalyst microspheres were obtained by controlling the spray drying conditions.

[0092] The catalyst microspheres obtained by spray drying were calcined, washed to remove sodium, and dried to obtain the cracking catalyst CAT-3 provided by the present invention.

[0093] The composition of catalyst CAT-3 is as follows: 43.1 wt% kaolin, 8 wt% alumina from boehmite, 8 wt% alumina from alumina sol, 1.8 wt% yttrium oxide, 0.6 wt% magnesium oxide, 0.5 wt% cerium oxide, 6 wt% high-silica ZSM-5 molecular sieve, and 32 wt% REUSY type molecular sieve. The particle size analysis results of CAT-3 are listed in Table 2.

[0094] Example 4

[0095] 1.69 kg (dry basis) of kaolin, 0.4 kg (alumina) of aluminum sol, 35 g (lanthanum oxide) of lanthanum carbonate and 5.7 kg of deionized water were added to a pulping tank and pulped. Then 0.95 kg (dry basis) of boehmite was added and stirred for 3.0 hours. Then 150 g of concentrated hydrochloric acid was added and stirred for 0.5 hours. Finally, the mixture was aged at 75°C for 2.0 hours.

[0096] 1.75 kg (dry basis) of REUSY molecular sieve, 50 g (dry basis) of low-silica ZSM-5 molecular sieve (from Lanzhou Petrochemical Company, silicon-to-aluminum ratio 31), 424 g of yttrium nitrate, and 2.5 kg of deionized water were mixed and pulped for 1.7 hours, then added to the above pulping tank and homogenized for 1.2 hours. The spray drying conditions were controlled to obtain catalyst microspheres.

[0097] The catalyst microspheres obtained by spray drying were calcined, washed to remove sodium, and dried to obtain the cracking catalyst CAT-4 provided by the present invention.

[0098] The catalyst CAT-4 consisted of: 33.8 wt% kaolin, 19 wt% alumina from boehmite, 8 wt% alumina from alumina sol, 2.5 wt% yttrium oxide from yttrium nitrate, 0.7 wt% lanthanum oxide from lanthanum carbonate, 1 wt% low-silica ZSM-5 molecular sieve, and 35 wt% REUSY-type molecular sieve. The particle size analysis results of CAT-4 are listed in Table 2.

[0099] Example 5

[0100] 1.62 kg (dry basis) of kaolin, 0.5 kg (alumina basis) of alumina sol, 35 g (cerium oxide basis) of cerium carbonate and 4.0 kg of deionized water were added to a pulping tank and pulped. Then 0.7 kg (dry basis) of boehmite was added and stirred for 1.6 hours. Then 109 g of concentrated hydrochloric acid was added and stirred for 1.4 hours. Finally, the mixture was aged at 62°C for 1.2 hours.

[0101] 1.5 kg (dry basis) of REUSY molecular sieve, 0.3 kg (dry basis) of high-silica ZSM-5 molecular sieve (from Lanzhou Petrochemical Company, with a silicon-to-aluminum ratio of over 300), 373 g of yttrium nitrate, 35 g (based on magnesium oxide) of magnesium carbonate, and 2.4 kg of deionized water were mixed and pulped for 1.3 hours. The mixture was then added to the pulping tank, along with 1684 g of silicon-aluminum material APM-7 (solid content 11.88%). The mixture was then homogenized for 2.2 hours, and spray drying was carried out under controlled conditions to obtain catalyst microspheres.

[0102] The catalyst microspheres obtained by spray drying were calcined, washed to remove sodium, and dried to obtain the cracking catalyst CAT-5 provided by the present invention.

[0103] The catalyst CAT-5 consisted of: 32.4 wt% kaolin, 14 wt% alumina from boehmite, 10 wt% alumina from alumina sol, 4 wt% aluminosilicate material APM-7, 2.2 wt% yttrium oxide from yttrium nitrate, 0.7 wt% cerium oxide from cerium carbonate, 0.7 wt% magnesia oxide from magnesium carbonate, 30 wt% REUSY-type molecular sieve, and 6 wt% high-silica ZSM-5 molecular sieve. The particle size analysis results of CAT-5 are listed in Table 2.

[0104] Comparative Example 2

[0105] Except for replacing 1.62 kg (dry basis) of kaolin with 1.82 kg (dry basis) of kaolin and not adding the silicon-aluminum material APM-7, the rest was the same as in Example 5, and the comparative cracking catalyst DCAT-2 was prepared.

[0106] The composition of catalyst DCAT-2 is as follows: 36.4 wt% kaolin, 14 wt% alumina from boehmite, 10 wt% alumina from alumina sol, 2.2 wt% yttrium oxide from yttrium nitrate, 0.7 wt% cerium oxide from cerium carbonate, 0.7 wt% magnesia oxide from magnesium carbonate, 30 wt% REUSY-type molecular sieve, and 6 wt% high-silica ZSM-5 molecular sieve. The particle size analysis results of DCAT-2 are listed in Table 2.

[0107] Example 6

[0108] 1.155 kg (dry basis) of kaolin, 0.85 kg (alumina basis) of alumina sol, 5 g (rare earth oxide basis) of rare earth chloride (from Lanzhou Petrochemical Company, rare earth oxide concentration 289.3 g / L), 508.3 g of magnesium chloride, 0.3 kg (dry basis) of boehmite and 0.86 kg of deionized water were added to a pulping tank and pulped for 1 hour. Then 45 g of concentrated hydrochloric acid was added, and the mixture was stirred for 0.5 hours. The mixture was then aged at 70°C for 2 hours.

[0109] 2.3 kg (dry basis) of REUSY molecular sieve, 0.1 kg (dry basis) of high-silica ZSM-5 molecular sieve (from Lanzhou Petrochemical Company, with a silica-alumina ratio of over 300), 644 g of yttrium nitrate, and 3.3 kg of deionized water were mixed and pulped for 0.5 hours, then added to the above-mentioned pulping tank and homogenized for 0.5 hours. The spray drying conditions were controlled to obtain catalyst microspheres.

[0110] The catalyst microspheres obtained by spray drying were calcined, washed to remove sodium, and dried to obtain the cracking catalyst CAT-6 provided by the present invention.

[0111] The composition of catalyst CAT-6 is as follows: 23.1 wt% kaolin, 6 wt% alumina from boehmite, 17 wt% alumina from alumina sol, 3.8 wt% yttrium oxide from yttrium nitrate, 0.1 wt% rare earth oxide from rare earth chloride, 2 wt% magnesium oxide from magnesium chloride, 46 wt% REUSY-type molecular sieve, and 2 wt% high-silica ZSM-5 molecular sieve. The particle size analysis results of CAT-6 are listed in Table 2.

[0112] Comparative Example 3

[0113] The rare earth phosphate-containing PREY-2 molecular sieve was prepared according to the method of Example 6 of CN1201864C, and the catalyst DCAT-3 of Comparative Example 3 was prepared according to the preparation method of catalyst H in Examples 7-14 of CN1201864C.

[0114] Preparation of PREY-2 molecular sieves containing rare earth phosphate:

[0115] Weigh 3.0 kg of NaY zeolite and add it to a stainless steel reaction vessel. Add 1.5 kg of ammonium sulfate, 280 g of rare earth oxides, and 30 kg of deionized water. Under stirring, adjust the pH of the exchange system to 3.0-3.5 with hydrochloric acid, raise the temperature to 95-100℃, and exchange for 0.5-1 hour. After filtration and washing, obtain a single-exchange rare earth Y-type molecular sieve. Then, subject the exchanged molecular sieve to hydrothermal ultrastabilization treatment at 600℃. The calcined molecular sieve undergoes a second exchange under the following conditions: 1.5 kg of ammonium sulfate, 30 kg of deionized water, 400 g of ammonium phosphate, pH 3.0-3.5, temperature 95-100℃, and exchange time 0.5-1 hour. Afterward, adjust the pH to approximately 7 with ammonia water, add 120 g of rare earth oxides, filter, wash, dry, and then undergo a hydrothermal calcination process at 600℃ to finally obtain a double-exchange, double-calcined PREY-2 molecular sieve.

[0116] The comparative catalyst DCAT-3 was prepared by mixing 5.0% REY, 1.5% ZSM-5, 34% PREY-2, 21% alumina, 11% alumina sol, 27.5% kaolin, and an appropriate amount of deionized water, followed by spraying, curing, washing, and drying. The particle size analysis results of DCAT-3 are listed in Table 2.

[0117] Table 2. Particle size analysis results of the catalyst, μm

[0118] catalyst D(0.1) D(0.5) D(0.9) Example 1 Catalyst CAT-1 27.463 48.191 73.406 Example 2 Catalyst CAT-2 36.083 60.433 97.735 Example 3 Catalyst CAT-3 33.815 58.656 94.203 Example 4 Catalyst CAT-4 30.464 52.589 89.076 Example 5 Catalyst CAT-5 37.269 63.921 100.165 Example 6 Catalyst CAT-6 34.623 61.102 96.325 Comparative Example 1: Catalyst DCAT-1 40.576 71.002 106.380 Comparative Example 2: Comparative Catalyst DCAT-2 39.661 65.147 104.587 Comparative Example 3: Catalyst DCAT-3 42.236 75.042 114.488

[0119] Catalyst CAT-1 prepared in Example 1, catalyst CAT-5 prepared in Example 5, comparative catalyst DCAT-1 prepared in Comparative Example 1, and comparative catalyst DCAT-2 prepared in Comparative Example 2 were subjected to catalytic cracking performance evaluation on a heavy oil micro-reaction evaluation device (ACE) after aging at 800°C and 100% water vapor for 10 hours. The evaluation results are listed in Table 3.

[0120] Table 3. Results of Selectivity Evaluation for Catalytic Cracking

[0121]

[0122] As shown in Table 3, compared with catalyst DCAT-1 prepared using Comparative Example 1, catalyst CAT-1 prepared using Example 1 of the present invention, although having a 15 percentage point lower molecular sieve content, has a 2.38 percentage point higher conversion rate. The total liquid yield and coke factor are comparable to those of catalyst Comparative Example 1, indicating that catalyst CAT-1 of the present invention has better cracking activity and selectivity. Regarding gasoline composition, compared with catalyst DCAT-1 prepared using Comparative Example 1, catalyst CAT-1 prepared using Example 1 of the present invention has a 4.47 percentage point lower olefin content and a 0.47 unit higher RON octane number in gasoline, indicating that catalyst CAT-1 of the present invention has the characteristic of reducing gasoline olefin content without reducing gasoline octane number.

[0123] Furthermore, as shown in Table 3, compared with catalyst DCAT-2 prepared using Comparative Example 2, catalyst CAT-5 prepared using Example 5 of the present invention has improved conversion rate and total liquid yield due to the addition of silicon-aluminum material APM-7 with Brønsted acid centers and hierarchical pore structure. At the same time, the olefin content in gasoline is reduced by 2.45 percentage points. This indicates that the catalyst with inorganic oxide support material has better cracking reaction activity and selectivity while reducing the olefin content in gasoline.

[0124] Catalysts CAT-2, CAT-3, CAT-4, and CAT-6 prepared in Examples 2, 3, 4, and 6, and catalyst DCAT-3 prepared in Comparative Example 3, were subjected to 10 hours of aging treatment at 800°C and 100% water vapor. Their catalytic cracking reaction performance was then evaluated on a riser evaluation device. The catalyst CAT-2 + 8% PCA-OCT octane enhancer in Example 2 refers to a mixture of catalyst CAT-2 and PCA-OCT octane enhancer (weight percentage) in a ratio of 92% to 8%. The PCA-OCT octane enhancer was produced by the Petrochemical Research Institute of China National Petroleum Corporation and is designated PCA-OCT. The evaluation results are listed in Table 4.

[0125] Table 4 Evaluation results of catalytic cracking reaction

[0126]

[0127]

[0128] As shown in Table 4, compared with catalyst DCAT-3 prepared using Comparative Example 3, catalyst CAT-2 prepared using Example 2 of the present invention, combined with 8 wt% PCA-OCT octane enhancer, showed a 0.66 percentage point increase in conversion rate, an increase in total liquid yield, a decrease in coke yield, a 10.41 percentage point decrease in gasoline olefins, and no decrease in octane number when the reaction temperature was reduced by 10°C. This indicates that catalyst CAT-2 of the present invention, after being combined with octane enhancer, has the characteristics of reducing gasoline olefin content without reducing gasoline octane number, and at the same time, the selectivity of the cracking reaction is better. Compared with catalyst DCAT-3 prepared using Comparative Example 3, catalysts CAT-3 and CAT-6 prepared using Examples 3 and 6 of this invention showed the same characteristics of reducing gasoline olefin content, not reducing gasoline octane number, and having better reaction selectivity. Catalyst CAT-4 prepared using Example 4 of this invention showed the characteristics of significantly reducing gasoline octane number and improving reaction selectivity. Since the catalyst does not contain shape-selective molecular sieves, its RON octane number is slightly lower than that of the comparative agent DCAT-3. In actual industrial applications, octane number enhancers can be compounded according to the requirements of the equipment for gasoline octane number.

[0129] In summary, this invention promotes the cracking and conversion of olefins within the gasoline distillation range by regulating the mass transfer, cracking reaction, and hydrogen transfer reaction processes during catalytic cracking, while reducing coking caused by excessive hydrogen transfer reactions. Simultaneously, the catalyst maintains good activity stability, promoting the conversion of heavy oil and diesel fractions with low olefin content into gasoline fractions. The catalyst of this invention uses rare-earth ultrastable Y-type molecular sieves with low rare-earth content as the main active component, with additional additions of yttrium and lanthanide rare earth elements. During catalyst preparation, spray conditions are controlled to ensure relatively fine catalyst sieving, which is beneficial for increasing the catalyst's surface area and activity, and shortening the diffusion path of reactant and product molecules within the catalyst microspheres.

[0130] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A catalytic cracking catalyst, characterized in that, The catalytic cracking catalyst comprises, by weight 100%, 15-50% rare earth ultrastable Y-type molecular sieve on a dry basis, 10-60% clay on a dry basis, 1-4% yttrium on an oxide basis, and 5-35% binder on an oxide basis. The rare earth content in the rare earth ultrastable Y-type molecular sieve is no more than 3%, calculated as oxides and based on the weight of the rare earth ultrastable Y-type molecular sieve as 100%.

2. The catalytic cracking catalyst according to claim 1, characterized in that, The catalytic cracking catalyst further includes lanthanide rare earth elements, and the weight content of the lanthanide rare earth elements in the catalytic cracking catalyst is 0.001-3% based on oxides.

3. The catalytic cracking catalyst according to claim 1, characterized in that, The catalytic cracking catalyst also includes other molecular sieves, and the weight content of the other molecular sieves in the catalytic cracking catalyst is 0.001-15% on a dry basis; the other molecular sieves are MFI shape-selective molecular sieves and / or USY molecular sieves.

4. The catalytic cracking catalyst according to claim 1, characterized in that, The catalytic cracking catalyst further includes magnesium and / or inorganic oxide support material; the magnesium is calculated as oxide, the inorganic oxide support material is calculated as oxide, the magnesium content in the catalytic cracking catalyst is 0-3%, and the inorganic oxide support material content is 0-30%.

5. The catalytic cracking catalyst according to claim 1, characterized in that, The average particle size of the catalytic cracking catalyst is 48–70 μm, and the cell constant of the rare earth ultrastable Y-type molecular sieve is 2.440–2.460 nm.

6. The catalytic cracking catalyst according to claim 1, characterized in that, Based on the weight of the rare earth ultrastable Y-type molecular sieve as 100%, the rare earth content in the rare earth ultrastable Y-type molecular sieve is 0.5 to 3 wt%, wherein the rare earth is at least one of yttrium and lanthanide rare earths.

7. The catalytic cracking catalyst according to claim 1, characterized in that, The clay is selected from at least one of kaolin, montmorillonite, diatomaceous earth, sepiolite, and bentonite; the binder is selected from at least one of boehmite, aluminum sol, silica sol, and aluminosilicate.

8. The catalytic cracking catalyst according to claim 4, characterized in that, The inorganic oxide carrier material is selected from at least one of silica, alumina containing Brønsted acid centers, and aluminosilicate containing Brønsted acid centers.

9. The method for preparing the catalytic cracking catalyst according to any one of claims 1-8, characterized in that, Includes the following steps: Rare earth ultrastable Y-type molecular sieve, clay, yttrium-containing compound and binder are mixed and slurried, then the slurry is spray-formed, dried, cured and washed with water to prepare a catalytic cracking catalyst.

10. The method for preparing the catalytic cracking catalyst according to claim 9, characterized in that, Rare earth ultrastable Y-type molecular sieves are first mixed and stirred with yttrium-containing compounds, and then mixed with clay and binder to form a slurry. The slurry is then spray-formed, dried, cured, and washed with water to prepare a catalytic cracking catalyst. The yttrium-containing compound is selected from at least one of yttrium halides, yttrium nitrates, yttrium carbonates, yttrium oxides, and yttrium hydroxides.

11. The method for preparing the catalytic cracking catalyst according to claim 9, characterized in that, The slurry also contains lanthanide rare earth compounds, which are selected from at least one of lanthanide rare earth halides, lanthanide rare earth nitrates, lanthanide rare earth carbonates, lanthanide rare earth oxides, and lanthanide rare earth hydroxides.

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