High-strength, large-pore-volume catalytic cracking aid and method for preparing same

Abstract

The application discloses a high-strength and large-pore catalytic cracking aid and a preparation method thereof. The catalytic cracking aid comprises a molecular sieve, a substrate, a binder and a metal chelate. The substrate is composed of a gamma-alumina precursor with a peptization index of less than or equal to 50% and clay. The binder is prepared from a phosphorus-containing compound and an aluminum-containing compound. The molecular sieve has an MFI structure, and the molecular sieve with a pore diameter less than 0.7 nm accounts for 50 wt% to 100 wt% of the total amount of the molecular sieve. The binder, the metal chelate and the substrate are mixed in a high-shear emulsifier. The catalytic cracking aid provided by the application can keep excellent wear resistance and strength under the premise of high molecular sieve content and large pore volume through the cooperation between the components and the dispersion and emulsification of the components in the high-shear emulsifier in the preparation process. When used as a propylene aid and an octane aid, the catalytic cracking aid can not only make the device run smoothly, but also improve the propylene and octane content.

Description

Technical Field

[0001] This invention belongs to the field of catalyst additive technology, specifically relating to a high-strength, large-pore-volume catalytic cracking additive and its preparation method. Background Technology

[0002] In catalytic cracking, the content of the target product varies significantly depending on the cracking catalyst and process technology used. Additives can effectively improve the yield of the target product. Propylene additives commonly use MFI-type zeolites, such as ZSM-5 molecular sieves, as the active component, kaolin as the carrier, and various silica-alumina gels as binders. Introducing phosphorus oxides into propylene additives can significantly improve the selectivity for propylene; therefore, phosphorus-alumina gel is currently widely used as a binder to enhance propylene selectivity. Besides its excellent propylene selectivity, phosphorus-alumina gel also possesses good binding properties, meeting the industrial requirements for catalyst strength.

[0003] However, existing catalytic cracking additives made using phosphorus-aluminum glue as a binder suffer from low molecular sieve content, small pore volume, low specific surface area, and poor strength. This leads to problems such as insignificant increase in target yield, decreased gasoline yield, deteriorated system activity, and significant strength differences compared to the main catalyst when applied in the catalytic cracking process. Consequently, these additives cause fluidization fluctuations in the unit, affecting its long-term stable operation. Increasing the content of the active component ZSM-5 molecular sieve and improving the pore volume of the catalytic cracking additive often results in a decrease in the additive's anti-wear performance, leading to abnormal fluidization, additive loss, fouling in the flue gas system, and increased solids content in the slurry, all of which negatively impact the long-term operation of the catalytic cracking unit.

[0004] For example, Chinese patent document CN102794194B discloses a method for preparing propylene additives for catalytic cracking, including steps of molecular sieve exchange, propylene additive preparation, and propylene additive washing. The molecular sieve exchange step includes: contacting the molecular sieve with an aqueous solution containing inorganic and organic acids at 0-5°C for 0.5-2 hours; the weight ratio of H2O to molecular sieve is 5-10:1; and using H2O to prepare the propylene additive. + The concentration of organic acid in the aqueous solution is 0.009-0.9 mol / L, and the concentration of inorganic acid is 0.001-0.1 mol / L. The washing step of the propylene additive includes: contacting the propylene additive with an aqueous solution containing inorganic and organic acids at 0-5°C for 10-100 minutes, wherein the weight ratio of H₂O to propylene additive is 5-9:1, with H₂O... + The concentration of organic acid in the aqueous solution is calculated to be 0.0001-0.2 mol / L, and the concentration of inorganic acid is 0.0001-0.1 mol / L. In this scheme, the additive is treated with acid after preparation to optimize the pore structure and acidity distribution. However, this method will reduce the cracking activity of the additive, especially the cracking activity of low-carbon olefins, and reduce the yield of the target product.

[0005] Chinese patent document CN103254925B discloses a catalytic cracking propylene additive and its preparation method. The additive, by total weight, comprises 20-60% HZSM-5 molecular sieve, 5-25% aluminum phosphate oxide, 6-12% silica-alumina gel carrier, and the remainder being kaolin. The molar ratio of SiO2 to Al2O3 in the HZSM-5 molecular sieve is (25-500):1. The aluminum phosphate oxide is aluminum phosphate, and the silica-alumina gel carrier is silica-alumina gel. The silica-alumina sol prepared by this method clogs the pores of the molecular sieve, and the pore volume and specific surface area of ​​the additive are relatively low.

[0006] Chinese patent document CN102049284B discloses a catalytic cracking propylene additive, which, based on 100% of the total additive weight, contains 30-80% by weight of molecular sieves, of which ZSM-5 zeolite content is 28-78% by weight, and clay content is 10-65% by weight. The additive contains phosphorus (P), specifically 5.0-20.0% by weight (preferably 7.0-15.0% by weight) as P2O5, and 0-1.0% by weight of La2O3. Aluminum phosphate sol is used as a binder, which improves the wear resistance of the additive and the solid content of the spray slurry, while avoiding chlorine content in the spray slurry and the additive. The additive prepared by this method uses aluminum phosphate binder, which, compared to conventional binders like silica-alumina sol, results in a smaller mesopore volume and an increased thermal abrasion index. This leads to the generation of a large amount of fine powder during equipment operation, affecting the stable operation of the equipment.

[0007] Chinese patent document CN107970983A discloses an additive comprising 10-75 wt% (dry weight) of a phosphorus-containing MFI structured molecular sieve, 3-40 wt% (dry weight) of a phosphorus-aluminum inorganic binder, 1-30 wt% (oxides) of other inorganic binders, 0-60 wt% (dry weight) of a second clay, and 0.5-15 wt% (oxides) of a metal additive selected from at least one of Group VIII metals and manganese, zinc, and gallium. In this method, when using an aluminum phosphate binder and modifying the molecular sieve with phosphorus, excessive phosphorus introduction in the additive can form stable PO-Al bonds with the aluminum on the molecular sieve, blocking the pores of the molecular sieve, causing a decrease in specific surface area, and affecting the reactivity of the additive.

[0008] Chinese patent document CN104549445A discloses a method for preparing a catalytic cracking additive. This method includes preparing a high-silica ZSM-5 molecular sieve, mixing the obtained high-silica ZSM-5 molecular sieve with a binder and clay, slurrying, and granulating. The preparation of the high-silica ZSM-5 molecular sieve includes: introducing NaZSM-5 molecular sieve powder into a gas-phase ultrastable reactor; moving the NaZSM-5 molecular sieve powder from the molecular sieve inlet to the molecular sieve outlet of the gas-phase ultrastable reactor without carrier gas transport; and allowing the NaZSM-5 molecular sieve powder to react with gas-phase SiCl4 in the gas-phase ultrastable reactor. This preparation method can continuously prepare ZSM-5 molecular sieves with a high silica-to-alumina ratio for the preparation of propylene catalytic cracking additives. However, this method first performs ultrastabilization treatment on the molecular sieve, followed by acid-base treatment, which severely damages the molecular sieve framework and affects the reactivity of the additive.

[0009] Chinese patent document CN102847551B discloses a cracking aid with high and low carbon olefin concentrations. The aid contains a phosphorus-aluminum inorganic binder containing a first clay, modified MFI molecular sieve, other inorganic binders, and V111 group metal additives, with or without a second clay. The phosphorus-aluminum inorganic binder containing the first clay includes 15-40% by weight of aluminum component based on Al2O3, 45-80% by weight of phosphorus component based on P2O5, and 1-40% by weight of the first clay on a dry basis. The preparation process of this additive involves treating the molecular sieve with acid and alkali to expand its pore structure, which is beneficial to increasing the pore volume and specific surface area of ​​the additive. However, this mesoporization process reduces the crystallinity of the molecular sieve and causes a large loss of surface acid sites, resulting in a decrease in cracking reaction performance. Furthermore, the molecular sieve is modified with transition metals such as phosphorus to improve its stability and reactivity, and aluminum phosphate binder is used. However, excessive phosphorus will further reduce the reactivity of the molecular sieve. On the other hand, conventional aluminum phosphate has poor thermal abrasion performance.

[0010] As mentioned earlier, existing technologies generally use a certain amount of ZSM-5 molecular sieve, silica sol, or aluminum-containing compounds as the aluminum source, and then add phosphorus-containing compounds, clay, and other components to prepare propylene additives. When preparing additives using the above methods, although the silica, aluminum sol, or partially aluminum-containing compounds and phosphorus-containing compounds forming a partially aluminum phosphate binder can increase the catalyst's wear resistance to some extent, its wear resistance is still insufficient when the molecular sieve content in the catalyst is high or the catalyst pore volume is large. The underlying mechanism is currently unclear; however, it has been found that when the molecular sieve content in the additive is high or the additive pore volume is large, the additive particles undergo varying degrees of breakage when prepared using existing methods, especially after high-temperature steam aging. It is speculated that these ions may have a stable bond with the binding component, keeping the binding component in an inactive state. During the preparation of the additives, they remain in an inactive state. On the one hand, this stable bond reduces the binding effect of the binding components. On the other hand, during the spray drying process, especially during steam aging, the chloride, ammonium, and nitrate ions that are stably bonded to the binding components become unstable, generating gases such as hydrogen chloride, ammonia, nitrogen, and oxygen. The generation of these gases causes numerous "bubbles" to form inside the additive particles. When the temperature rises, these bubbles burst out of the additive, damaging the particle shape and, in severe cases, causing the particles to rupture. This reduces the binding effect of various binders and significantly lowers the anti-wear performance of the additives. Furthermore, existing propylene octane number additives use large amounts of phosphoric acid to modify the molecular sieve to improve its activity and stability. However, the use of phosphorus reacts with the non-framework aluminum of the ZSM-5 molecular sieve, forming firmly bonded PO-Al bonds that block the pores of the molecular sieve, resulting in a decrease in the crystallinity, specific surface area, and activity of the ZSM-5 molecular sieve. Additionally, a large amount of phosphorus is discharged with wastewater during the additive preparation process, causing excessive phosphorus content in the wastewater and impacting the environment. Summary of the Invention

[0011] To overcome the above-mentioned shortcomings, the present invention provides a high-strength, large-pore-volume catalytic cracking aid and its preparation method. Compared with existing catalytic cracking aids, the catalytic cracking aid provided by the present invention has higher wear resistance, larger pore volume, higher molecular sieve content, and higher yield of target products for catalytic cracking.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] A high-strength, large-pore-volume catalytic cracking promoter includes a molecular sieve, a matrix, a binder, and a metal chelate. The matrix is ​​composed of a γ-alumina precursor with a colloidal index ≤50% and clay. The binder is prepared from a phosphorus-containing compound and an aluminum-containing compound.

[0014] The molecular sieve having an MFI structure and a pore diameter of less than 0.7 nm accounts for 50 wt% to 100 wt% of the total molecular sieve.

[0015] The binder, the metal chelate, and the matrix are all mixed in a high-shear emulsifier.

[0016] Optionally, in the catalytic cracking aid provided by the present invention, the metal chelate is selected from at least one of phosphonic acid metal chelates, aminocarboxylic acid metal chelates, hydroxyaminocarboxylic acid metal chelates, carboxylic acid metal chelates, carbonyl metal chelates, etc.

[0017] Optionally, in the catalytic cracking additive provided by the present invention, the metal chelate is a mixture of at least two metal chelates or a multi-metal chelate containing at least two metals, wherein the metal in the metal chelate is at least one of rare earth metal ions, transition metal ions, alkali metal ions, and alkaline earth metal ions; preferably, the metal in the metal chelate is a transition metal ion and a rare earth metal ion; the ratio of various metal ions in the metal chelate is not specifically limited, and can be adjusted according to the actual situation. The present invention recommends a molar ratio of transition metal ions to rare earth metal ions in the metal chelate of 5 to 15:1.

[0018] Preferably, the rare earth metal ions are selected from light rare earth metal ions, such as lanthanum ions, cerium ions, neodymium ions, samarium ions, etc.; the transition metal ions are selected from copper, silver, nickel, zinc, cobalt, cadmium, etc.

[0019] Optionally, in the catalytic cracking catalyst provided by the present invention, the metal chelate is selected from at least one of the following: lanthanum chelated with hydroxyethyl ethylenediamine triacetic acid, cerium chelated with hydroxyethyl ethylenediamine triacetic acid, copper chelated with ethylenediaminetetraacetic acid, silver chelated with ethylenediaminetetraacetic acid, copper chelate of aminotrimethylphosphonic acid, silver chelate of n-acyl ethylenediamine triacetic acid, zinc chelate of aminotrimethylphosphonic acid, lanthanum chelated with DOTA, yttrium chelate of β-diketone rare earth, cerium chelate of β-diketone rare earth, and copper and lanthanum bimetallic hydroxyethyl ethylenediamine triacetic acid chelate.

[0020] Optionally, in the catalytic cracking aid provided by the present invention, the ratio of the total molar amount of metal ions in the metal chelate to the molar amount of phosphorus in the phosphorus-containing compound is 5 to 20:1.

[0021] Optionally, in the catalytic cracking additive provided by the present invention, the molecular sieve further includes at least one of BEA structure, FER structure, MWW structure, MOR structure, AST structure, and FAU structure molecular sieves; preferably, the molecular sieve is a mixed molecular sieve composed of two different structures (i.e., a mixture of MFI structure molecular sieve and any other type of molecular sieve), and the specific surface area of ​​the mixed molecular sieve is not less than 400-500 m². 2 / g, the Si / Al molar ratio in the MFI structured molecular sieve is 10-200.

[0022] Specifically, any molecular sieve with a different structure can be a conventional one used in the industry, without any specific limitations. For example, molecular sieves with an MFI structure can be selected from high-silica ZSM-5, low-silica ZSM-5, phosphorus-modified ZSM-5, phosphorus-iron modified ZSM-5 molecular sieves, or TS-1 molecular sieves, etc.; molecular sieves with a BEA structure can be selected from high-silica Beta molecular sieves, low-silica Beta molecular sieves, etc.; molecular sieves with an FER structure can be selected from ZSM-35 molecular sieves, etc.; molecular sieves with an MWW structure can be selected from MCM-22, MCM-41, etc.; molecular sieves with a MOR structure can be selected from mordenite, etc.; molecular sieves with an AST structure can be selected from pure silica AST molecular sieves, etc.; and molecular sieves with a FAU structure can be selected from Y-type molecular sieves, rare earth Y-type molecular sieves, dealulated Y-type molecular sieves, ultrastable Y-type molecular sieves, etc.

[0023] Optionally, in the catalytic cracking additive provided by the present invention, the molar ratio of phosphorus in the phosphorus-containing compound to aluminum in the aluminum-containing compound is 2-10:1, preferably 4-8:1. The aluminum-containing compound and the phosphorus-containing compound are not specifically limited and can be conventional in the industry. The aluminum-containing compound includes, but is not limited to, aluminum oxides, aluminum hydroxides, and aluminum-containing organic compounds, such as aluminum oxide, aluminum hydroxide, sodium aluminate monohydrate, aluminum chloride, and aluminum isopropoxide; preferably, aluminum oxides and aluminum hydroxides. The phosphorus-containing compound includes, but is not limited to, phosphorus oxides, phosphorus oxyacids, phosphoric acid, phosphates, or phosphorus-containing organic compounds, such as phosphoric acid, diammonium hydrogen phosphate, phosphorus pentoxide, organophosphonic acid, sodium phosphate, and calcium phosphate. Preferably, phosphorus oxyacids, phosphoric acid, and phosphorus-containing ammonium salts are used.

[0024] Optionally, in the catalytic cracking aid provided by the present invention, the colloid index of the γ-alumina precursor is 20% to 30%; preferably, the XRD pattern of the γ-alumina precursor shows characteristic peaks at 2θ of 14±1°, 28±1°, 38±1°, and 49±1°, such as boehmite, boehmite, etc.

[0025] Optionally, in the catalytic cracking aid provided by the present invention, the mass ratio of the γ-alumina precursor to the clay is 1:0.5 to 15, preferably 1:2 to 9.

[0026] Optionally, in the catalytic cracking additive provided by the present invention, the clay in the matrix can be any clay commonly used in the art, all of which can meet the requirements of the present invention, such as one or more of the components commonly used as catalytic cracking additives, including kaolin, hydrous kaolin, montmorillonite, diatomaceous earth, bentonite, and silicide. Preferably, the clay is selected from kaolin, silicide, hydrous kaolin, or mixtures thereof.

[0027] Optionally, in the catalytic cracking aid provided by the present invention, based on the total dry weight of the catalytic cracking aid as 100%, the content of the molecular sieve is 20wt% to 70wt%, the content of the matrix is ​​10wt% to 40wt%, the content of the binder is 10wt% to 30wt%, and the content of the metal chelate is 2wt% to 10wt%.

[0028] The preparation method of the above-mentioned high-strength, large-pore-volume catalytic cracking additive recommended by this invention includes the following steps:

[0029] Acid treatment: Molecular sieves with Na2O content ≤0.1wt% are mixed with deionized water to form a molecular sieve slurry. A mixture of organic and inorganic acids is added until the pH of the molecular sieve slurry is ≤2.0 and the reaction is carried out. After the reaction is completed, a metal chelate is added and the reaction is carried out. After the reaction is completed, the slurry is dried and calcined to obtain the acid-treated molecular sieve.

[0030] Mixed slurry: The acid-treated molecular sieve is mixed with deionized water, and then the pH of the slurry is adjusted to ≤2.0. It is then added to a high-shear emulsifier, followed by the addition of aluminum-containing compounds and phosphorus-containing compounds, and metal chelates. The mixture is then thoroughly mixed to obtain a mixed slurry of aluminum phosphate binder and molecular sieve.

[0031] Calcination and molding: Add matrix slurry to the mixed slurry of aluminum phosphate binder and molecular sieve, and continue to mix in a high-shear emulsifier for 5 minutes. Then, perform spray molding and drying, and calcination to obtain the high-strength, large-pore-volume catalytic cracking aid.

[0032] Optionally, in the preparation method of the high-strength, macroporous catalytic cracking additive provided by the present invention, the metal chelate in the acid treatment step may be the same as or different from the metal chelate in the mixed slurry step. Preferably, in the mixed slurry step, the metal chelate is a mixture of at least two metal chelates or a multi-metal chelate containing at least two metals. Preferably, in the acid treatment step, the metal chelate is a metal chelate containing only one metal.

[0033] Optionally, in the preparation method of the high-strength, large-pore-volume catalytic cracking additive provided by the present invention, the main purpose of adding a metal chelate to the acid-treated molecular sieve slurry in the acid treatment step is to modify the molecular sieve. Preferably, a chelate containing rare earth metals is added, as rare earth metals can more readily distribute the metal uniformly on the molecular sieve surface, thereby modulating the acid distribution on the molecular sieve surface and preventing the strong acid centers on the molecular sieve surface from weakening during acid treatment, which would affect the reaction performance. Simultaneously, due to the occupancy effect of the metal chelate, a rich mesoporous structure can be formed during the preparation of the additive.

[0034] Optionally, in the preparation method of the high-strength, large-pore-volume catalytic cracking additive provided by the present invention, when the Na2O content in the molecular sieve is greater than 0.1wt%, the method further includes an ammonium exchange step of the molecular sieve, comprising the following steps: exchanging the molecular sieve with ammonium salt until the Na2O content in the molecular sieve is ≤0.1wt%, separating, and drying to obtain a molecular sieve with a Na2O content ≤0.1wt% after ammonium exchange; ammonium exchange of molecular sieve is a conventional processing technology in the field, and existing conventional ammonium exchange processes can meet the implementation of the technical solution of the present invention, and are not specifically limited or described in detail here.

[0035] Optionally, in the preparation method of the high-strength, macroporous catalytic cracking additive provided by the present invention, in the acid treatment step, the organic and inorganic acids in the mixed acid of organic and inorganic acids can be conventional in the industry and are not specifically limited, such as hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, citric acid, tartaric acid, etc. Preferably, the pH of the system after adding the mixed acid of organic and inorganic acids is ≤1.0, and more preferably, the molar ratio of organic acid to inorganic acid is 2 to 5:1.

[0036] Optionally, in the preparation method of the high-strength, macroporous catalytic cracking additive provided by the present invention, the reaction parameters after adding the metal chelate in the acid treatment step are not specifically limited, and conventional parameters in the industry can be used. For example, the reaction can be carried out at 60-100°C for 0.5-12 hours, preferably 3-10 hours. The reaction apparatus involved in this step is not specifically limited, as long as it has a reflux device. For example, the reaction can be carried out in a heated kettle with a reflux device.

[0037] Optionally, in the preparation method of the high-strength, large-pore-volume catalytic cracking additive provided by the present invention, the molar ratio of the metal chelate added in the acid treatment step to the metal chelate added in the mixed slurry step is 1:1 to 4.

[0038] Optionally, in the preparation method of the high-strength, large-pore-volume catalytic cracking additive provided by the present invention, during the acid treatment step, 100% water vapor is introduced during the first 2 / 3 of the calcination time, and air is introduced during the last 1 / 3 of the time. Calcination under water vapor conditions during the first 2 / 3 of the time is beneficial for stabilizing the molecular sieve and improving its stability; calcination under water vapor-free conditions during the last 1 / 3 of the time can quickly and thoroughly calcinate the organic matter in the additive. Due to the occupancy effect of the organic matter, complete calcination is beneficial for forming a large number of pores within the additive.

[0039] Optionally, in the preparation method of the high-strength, large-pore-volume catalytic cracking additive provided by the present invention, the calcination parameters in the acid treatment step are not specifically limited, and conventional parameters in the industry can be used, such as limiting the calcination temperature to 400-800℃ and the time to 2-5h.

[0040] Optionally, in the preparation method of the high-strength, large-pore-volume catalytic cracking additive provided by the present invention, in the calcination and molding step, by controlling the mixing time of the molecular sieve and the in-situ formed aluminum phosphate binder slurry and the matrix slurry in the high-shear emulsifier to be no more than 5 minutes, it is equivalent to achieving instantaneous and thorough mixing. The mixture is then immediately output and spray-dried, realizing continuous "mixing, conveying, drying and molding," avoiding prolonged contact between the mixed slurry and the binder, which could lead to phosphorus migration and a reduction in the surface area and pore volume of the molecular sieve. Preferably, the mixing time of the molecular sieve and aluminum phosphate binder slurry and the matrix slurry in the high-shear emulsifier is no more than 3 minutes.

[0041] Optionally, in the preparation method of the high-strength, large-pore-volume catalytic cracking additive provided by the present invention, the preparation of the matrix slurry is a well-known operation in the art. Specifically, it is sufficient to mix and slurry the γ-alumina precursor, clay and deionized water, without any special requirements.

[0042] Optionally, in the preparation method of the high-strength, large-pore-volume catalytic cracking additive provided by the present invention, the spray molding drying refers to the granulation and drying of the material, which is a technology known to those skilled in the art. Existing parameters can be used. For example, the process conditions for spray molding drying in the preparation of catalytic cracking additives are generally as follows: the temperature of the spray tower furnace is controlled at 450-600℃, and the temperature of the spray tail gas is controlled at 150-300℃.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] Beneficial Effect 1: The catalytic cracking additive provided by this invention, by adding metal chelates, can modify the aluminum phosphate binder prepared from phosphorus-containing and aluminum-containing compounds, preventing high levels of binder from clogging the pores in the additive during preparation; and reduce the amount of acid added during additive preparation, increasing the pH value of the slurry, thereby reducing acid corrosion on the molecular sieve structure and improving catalyst activity. On the other hand, it can modify the molecular sieve to modulate the acid distribution on its surface, while utilizing the site-occupancy effect of the metal chelates to form a rich mesoporous structure. Using a low-solubility-index γ-alumina precursor as one of the matrix materials can, on the one hand, reduce the solubility of the γ-alumina precursor in the acidic medium during catalyst preparation, reducing the clogging of catalyst and zeolite molecular sieve pores by the dissolved alumina, while precisely controlling the presence of free aluminum in the catalyst system, avoiding excessive reaction with the effective components of the binder, thus affecting the binder's bonding performance. A small portion of the dissolved γ-alumina precursor can react with phosphorus-containing compounds in the binder under specific conditions to form a binder. On the other hand, γ-alumina precursors with low colloidal index can form a large number of mesopores during catalyst curing, thereby increasing the pore volume of the catalyst.

[0045] The catalytic cracking additive provided by this invention, through the synergistic interaction of its components and the use of a high-shear emulsifier to disperse and emulsify these components during the preparation process, ultimately maintains excellent wear resistance despite having a high molecular sieve content and large pore volume. When used as a propylene additive and octane number additive, it not only ensures stable operation of the equipment but also increases the propylene and octane content.

[0046] Beneficial Effect 2: The preparation method of the catalytic cracking additive provided by this invention involves mixing inorganic and organic acids to treat the active component molecular sieve, thereby controlling its pore structure and morphology, increasing the pore volume and specific surface area of ​​the molecular sieve; simultaneously, it regulates the surface acidity of the molecular sieve, reducing strong acid centers and the proportion of Brønsted acid and Lewis acid. This significantly improves propylene selectivity while increasing LPG yield, enhances aromatization ability, and increases gasoline octane number. By pre-stabilizing the molecular sieve, the pore size and specific surface area of ​​the molecular sieve are increased, while the activity stability of the molecular sieve is greatly improved, and the activity retention rate under high temperature and hydrothermal conditions is increased. Therefore, in the preparation of the additive, it is not necessary to introduce too much phosphorus to modify the molecular sieve, reducing the reaction between phosphorus and the non-framework aluminum of the molecular sieve (introducing too much phosphorus during the preparation process will react with the non-framework aluminum of the molecular sieve to form a stable PO-Al bond, which will block the pores of the molecular sieve and reduce the crystallinity, specific surface area and activity of the molecular sieve). In addition, since it is not necessary to introduce too much phosphorus during the preparation of the additive, it can effectively avoid the discharge of a large amount of phosphorus with the wastewater (causing the phosphorus content in the wastewater to exceed the standard), and will not have an impact on the environment.

[0047] Beneficial Effect 4: The preparation method of the catalytic cracking additive provided by the present invention involves in-situ synthesis of the binder, followed by the addition of a metal chelate to modify the binder. On the one hand, this effectively avoids the introduction of impurities from the molecular sieve or other heteroatoms into the binder, thus preventing impurities introduced during the formation of aluminum phosphate crystals from affecting the crystallinity of the aluminum phosphate crystals and causing collapse under high-temperature hydrothermal conditions (i.e., preventing chloride, ammonium, and nitrate ions from forming a strong bond with the binder, reducing the bubbles formed during the curing and calcination process, and thus forming defect sites in the additive leading to collapse). On the other hand, and more importantly, the introduction of metal chelates after in-situ synthesis of the binder allows the metal ions (transition metal ions, alkali metal ions, and / or light rare earth metal ions, etc.) in the chelates to modify the aluminum phosphate binder, strengthening the interaction between aluminum phosphate and the matrix material and zeolite molecular sieve, and improving the bonding strength between the binder and other components. Experiments show that the metal ions in the binder provided in this invention can significantly reduce thermal collapse under high-temperature hydrothermal conditions, thereby greatly improving the thermal wear performance of the additive. Simultaneously, the introduction of metal chelates into the binder avoids premature hardening of the colloid during the later stages of additive molding and drying, preventing the blockage of additive pores and the resulting decrease in reactivity, thus increasing the pore volume of the additive. Numerous experimental results demonstrate that adding metal chelates to the aluminum phosphate binder allows the formation of micropores and mesopores within the binder during preparation, thereby increasing the pore volume of the catalyst without affecting the binder's bonding performance.

[0048] Beneficial Effect 5: The reaction apparatus for the acid treatment step in the preparation method of the catalytic cracking additive provided by this invention is not specifically limited, as long as it can be implemented. In the preparation step of the mixed slurry, when the binder is synthesized in situ and the synthesized binder is mixed and emulsified with the metal chelate and the matrix slurry, a high-shear emulsifier is required. On the one hand, it can disperse the low colloidal index γ-alumina precursor into a uniform and viscous emulsion slurry and efficiently mix it with the molecular sieve, overcoming the technical problem that the low colloidal index γ-alumina precursor has poor solubility and cannot form a uniform slurry; at the same time, the γ-alumina precursor exists in a non-free state, avoiding the over-reaction with phosphorus-containing compounds in the binder. On the other hand, the application of the high-shear emulsifier solves the problem that the metal chelate and aluminum phosphate binder cannot be fully mixed, promotes the mutual reaction between the aluminum phosphate binder and the metal chelate, effectively controls the microenvironment such as the supersaturation distribution in the reactor, and improves the role of the binder-modifying component metal chelate. More importantly, the application of the high-shear emulsifier enables efficient and short-time mixing of the binder, molecular sieve, and matrix slurry, achieving rapid emulsification of the low-solubility γ-alumina precursor and thorough homogenization of the binder and the mixed slurry. After uniform mixing, spray drying is immediately performed to prevent phosphorus migration caused by prolonged contact between the binder and molecular sieve, thus achieving the encapsulation and positioning of phosphorus in the aluminum phosphate binder. This plays an irreplaceable role in improving the reactivity of additives. Detailed Implementation

[0049] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0050] For any experimental steps or conditions not specified in the examples and comparative examples, the procedures and conditions described in the literature in this field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0051] The raw materials and equipment involved in this invention are all commercially available and can all meet the requirements for implementing the technical solution of this invention. However, for ease of comparison, the raw materials from the following sources are used in the following embodiments:

[0052] Y-type molecular sieve, ZSM-5 molecular sieve, and Beta molecular sieve were sourced from Lanzhou Petrochemical Company.

[0053] Aluminum hydroxide, phosphoric acid, diammonium hydrogen phosphate, aluminum oxide, copper nitrate, lanthanum chloride, copper chelate with ethylenediaminetetraacetic acid, silver chelate with ethylenediaminetetraacetic acid, cerium chelate with ethylenediaminetetraacetic acid, zinc chelate with aminotrimethylphosphonic acid, lanthanum chelate with DOTA, yttrium rare earth chelate with β-diketone, cerium rare earth chelate with β-diketone, and copper and lanthanum bimetallic hydroxyethyl ethylenediaminetetraacetic acid chelate; all were of analytical grade and manufactured by Sinopharm Group.

[0054] Boehmite, produced by Chalco Shandong Aluminum.

[0055] Evaluation and analysis methods:

[0056] The surface area of ​​the catalyst was determined by the low-temperature nitrogen adsorption-desorption method (NB / SH / T0959);

[0057] The pore volume of the catalyst was tested using the water droplet method (NB / SH / T0955);

[0058] The catalyst attrition index was determined using the straight tube method (NB / SH / T0964);

[0059] The reaction performance of the additive was evaluated using an ACE small fixed fluidized bed device. The additive (the catalytic cracking additive prepared in each embodiment and comparative example of this invention) was formulated with feedstock oil from a 3 million tons / year catalytic cracking unit of Lanzhou Petrochemical and the main catalyst at a ratio of 10 wt%. The test conditions were: reaction temperature 530℃, dosage 9g, and additive-to-oil ratio 5.0. The product was analyzed using an Agilent 6890 gas chromatograph.

[0060] Example 1

[0061] The catalytic cracking additive provided in this embodiment, based on the total dry weight of the catalytic cracking additive as 100%, contains 10wt% ZSM-5 molecular sieve, 10wt% Y-type molecular sieve, 10wt% metal chelate, 26.5wt% boehmite, 13.5wt% kaolin, and 30wt% binder (P / Al molar ratio of 2:1).

[0062] The specific preparation method is as follows:

[0063] Ammonium exchange: After exchanging ZSM-5 molecular sieve with Si / Al (mol) ratio of 100 and Y-type molecular sieve with ammonium chloride, the molar content of Na2O in the mixed molecular sieve is reduced to below 0.1 wt%.

[0064] Acid treatment: The above-mentioned ammonium-exchanged mixed molecular sieves were mixed with deionized water to obtain a molecular sieve slurry. Then, a mixture of dilute hydrochloric acid and citric acid (molar ratio of hydrochloric acid to citric acid was 2:1) was added to the molecular sieve slurry. After the acid was added, the pH of the system was 2.0. The temperature was raised to 60°C and the reaction was carried out in a reactor with a reflux device for 12 hours. After the reaction was completed, hydroxyethyl ethylenediamine triacetic acid was added to chelate lanthanum metal chelate. The mixture was stirred at the same temperature for another hour. The material obtained after the reaction was dried at 120°C for 12 hours and then calcined at 400°C for 5 hours (100% steam was introduced for the first 200 minutes of calcination and air was introduced for the last 100 minutes of calcination).

[0065] Mixed slurry: The calcined molecular sieve obtained from the acid treatment step is mixed with deionized water, and dilute hydrochloric acid is added to stabilize the pH of the system at 1.0. The mixture is then added to a high-shear emulsifier, followed by the addition of aluminum hydroxide and heating to 60°C. After uniform dispersion, aluminum dihydrogen phosphate is added in proportion, and the mixture is kept at 60°C for a rapid reaction of 10 min. Then, a mixed solution of copper chelated with ethylenediaminetetraacetic acid and lanthanum chelated with hydroxyethylethylenediaminetriacetic acid is added (the ratio of the total molar amount of copper and lanthanum to the molar amount of phosphorus is 5:1, and the molar ratio of copper to lanthanum is 5:1). The mixture is then reacted at 60°C for another 5 min to obtain a mixed slurry of aluminum phosphate binder and molecular sieve.

[0066] Calcination and molding: Add matrix slurry (obtained by uniformly mixing boehmite, kaolin, and deionized water with a gel solubility index of 50%) to the above-mentioned aluminum phosphate binder and molecular sieve mixture slurry, and continue high-speed emulsification in a high-shear emulsifier for 2 minutes. Then, immediately export it for spray molding and drying. The spray molding conditions are that the furnace temperature of the spray tower is controlled at 580℃ and the temperature of the spray tail gas is controlled at 160℃. After calcining at 600℃ for 2 hours, the obtained material becomes the catalytic cracking aid.

[0067] The molar ratio of the metal chelate added in the acid treatment step to the metal chelate added in the mixed slurry step is 1:4.

[0068] The physicochemical and catalytic properties of this catalytic cracking aid are shown in Table 1.

[0069] Example 2

[0070] The catalytic cracking additive provided in this embodiment, based on the total dry weight of the catalytic cracking additive as 100%, contains 49 wt% ZSM-5 molecular sieve, 21 wt% Beta molecular sieve, 2 wt% metal chelate, 3.5 wt% boehmite, 6.5 wt% halloysite, and 18 wt% binder (P / Al molar ratio of 10:1).

[0071] The specific preparation method is as follows:

[0072] Ammonium exchange: After exchanging ZSM-5 molecular sieve with Si / Al (mol) ratio of 50 and Beta molecular sieve with ammonium chloride, the molar content of Na2O in the mixed molecular sieve is reduced to below 0.1 wt%.

[0073] Acid treatment: The above-mentioned ammonium-exchanged mixed molecular sieves are mixed with deionized water to obtain a molecular sieve slurry. Then, a mixture of dilute hydrochloric acid and oxalic acid (molar ratio of hydrochloric acid to oxalic acid is 5:1) is added to the molecular sieve slurry. After the acid is added, the pH of the system is 1.0. The temperature is raised to 100°C and reacted in a reactor with a reflux device for 3 hours. After the reaction is completed, hydroxyethyl ethylenediamine triacetic acid is added to chelate lanthanum metal chelate. The mixture is stirred at the same temperature for another 0.5 hours. The material obtained after the reaction is dried at 120°C for 12 hours and then calcined at 800°C for 2 hours (100% steam is introduced for the first 80 minutes of calcination and air is introduced for the last 40 minutes of calcination).

[0074] Mixed slurry: The calcined molecular sieve obtained from the acid treatment step is mixed with deionized water, and dilute nitric acid is added to stabilize the pH of the system at 0.50. The mixture is then added to a high-shear emulsifier, followed by the addition of aluminum oxide and heating to 60°C. After uniform dispersion, phosphoric acid is added in proportion, and the mixture is rapidly reacted at 100°C for 10 minutes. Then, a mixed solution of silver chelated with ethylenediaminetetraacetic acid and cerium chelated with hydroxyethylethylenediaminetriacetic acid is added (the ratio of the total molar amount of silver and cerium to the molar amount of phosphorus is 20:1, and the molar ratio of silver to cerium is 15:1). The mixture is then reacted at 100°C for another 3 minutes to obtain a mixed slurry of aluminum phosphate binder and molecular sieve.

[0075] Calcination and molding: Add matrix slurry (obtained by uniformly mixing boehmite, halloysite and deionized water with a colloidal index of 10%) to the above-mentioned aluminum phosphate binder and molecular sieve mixture slurry, and continue high-speed emulsification in a high-shear emulsifier for 4 minutes. Then, immediately export it for spray molding and drying. The spray molding conditions are that the furnace temperature of the spray tower is controlled at 580℃ and the temperature of the spray tail gas is controlled at 160℃. After calcining at 600℃ for 2 hours, the obtained material becomes the catalytic cracking aid.

[0076] The molar ratio of the metal chelate added in the acid treatment step to the metal chelate added in the mixed slurry step is 1:1.

[0077] The physicochemical and catalytic properties of this catalytic cracking aid are shown in Table 1.

[0078] Example 3

[0079] The catalytic cracking aid provided in this embodiment, based on the total dry weight of the catalytic cracking aid as 100%, contains 26 wt% ZSM-5 molecular sieve, 11 wt% MCM-22 molecular sieve, 8 wt% metal chelate, 2.2 wt% boehmite, 32.8 wt% diatomite, and 20 wt% binder (P / Al molar ratio of 4:1).

[0080] The specific preparation method is as follows:

[0081] Ammonium exchange: After exchanging ZSM-5 molecular sieve with Si / Al (mol) ratio of 30 and MCM-22 molecular sieve with ammonium chloride, the molar content of Na2O in the mixed molecular sieve is reduced to below 0.1 wt%.

[0082] Acid treatment: The above-mentioned ammonium-exchanged mixed molecular sieves are mixed with deionized water to obtain a molecular sieve slurry. Then, a mixture of dilute nitric acid and citric acid (molar ratio of nitric acid to citric acid is 3:1) is added to the molecular sieve slurry. After the acid is added, the pH of the system is 1.0. The temperature is raised to 80°C and reacted in a reactor with a reflux device for 6 hours. After the reaction is completed, hydroxyethyl ethylenediamine triacetic acid is added to chelate cerium metal chelate. The mixture is stirred at the same temperature for another 0.5 hours. The material obtained after the reaction is dried at 120°C for 12 hours and then calcined at 600°C for 3 hours (100% steam is introduced for the first 120 minutes of calcination and air is introduced for the last 60 minutes of calcination).

[0083] Mixed slurry: The calcined molecular sieve obtained from the acid treatment step is mixed with deionized water, and dilute hydrochloric acid is added to stabilize the pH of the system at 0.5. The mixture is then added to a high-shear emulsifier, followed by the addition of aluminum chloride and heating to 80°C. After uniform dispersion, organophosphonic acid is added in proportion, and the mixture is rapidly reacted at 80°C for 10 minutes. Then, a mixed solution of aminotrimethylphosphonic acid chelated zinc and DOTA chelated lanthanum is added (the ratio of the total molar amount of zinc and lanthanum to the molar amount of phosphorus is 5:1, and the molar ratio of zinc to lanthanum is 10:1). The mixture is then reacted at 80°C for another 3 minutes to obtain a mixed slurry of aluminum phosphate binder and molecular sieve.

[0084] Calcination and molding: Add matrix slurry (obtained by uniformly mixing boehmite, diatomaceous earth and deionized water with a gel solubility index of 30%) to the above-mentioned aluminum phosphate binder and molecular sieve mixture slurry, and continue high-speed emulsification in a high-shear emulsifier for 1 minute, and then immediately export it for spray molding and drying. The spray molding conditions are that the furnace temperature of the spray tower is controlled at 580℃ and the temperature of the spray tail gas is controlled at 160℃. After the obtained material is calcined at 600℃ for 2 hours, it becomes a catalytic cracking aid.

[0085] The molar ratio of the metal chelate added in the acid treatment step to the metal chelate added in the mixed slurry step is 3:5.

[0086] The physicochemical and catalytic properties of this catalytic cracking aid are shown in Table 1.

[0087] Example 4

[0088] The catalytic cracking additive provided in this embodiment, based on the total dry weight of the catalytic cracking additive as 100%, contains 35wt% ZSM-5 molecular sieve, 9wt% Y-type molecular sieve, 4wt% metal chelate, 3.6wt% boehmite, 33.4wt% bentonite, and 15wt% binder (P / Al molar ratio of 8:1).

[0089] The specific preparation method is as follows:

[0090] Ammonium exchange: After exchanging ZSM-5 molecular sieve with Si / Al (mol) ratio of 200 and Y-type molecular sieve with ammonium chloride, the molar content of Na2O in the mixed molecular sieve is reduced to below 0.1 wt%.

[0091] Acid treatment: The above-mentioned ammonium-exchanged mixed molecular sieve is mixed with deionized water to obtain a molecular sieve slurry. Then, a mixture of dilute hydrochloric acid and citric acid (molar ratio of hydrochloric acid to citric acid is 3:1) is added to the molecular sieve slurry. After the acid is added, the pH of the system is 0.5. The temperature is raised to 80°C and reacted in a reactor with a reflux device for 10 hours. After the reaction is completed, β-diketone rare earth yttrium chelate is added. The mixture is stirred at the same temperature for another 0.5 hours. The material obtained after the reaction is dried at 80°C for 10 hours and then calcined at 600°C for 3 hours (100% steam is introduced for the first 120 minutes of calcination and air is introduced for the last 60 minutes of calcination).

[0092] Mixed slurry: The calcined molecular sieve obtained from the acid treatment step is mixed with deionized water, and dilute sulfuric acid is added to stabilize the pH of the system at 1.0. The mixture is then added to a high-shear emulsifier, followed by the addition of aluminum nitrate and heating to 60°C. After uniform dispersion, diamine hydrogen phosphate is added in proportion, and the mixture is rapidly reacted at 100°C for 10 minutes. Then, a mixed solution of silver chelated with ethylenediaminetetraacetic acid and cerium chelated with hydroxyethyl ethylenediaminetriacetic acid is added (the ratio of the total molar amount of silver and cerium to the molar amount of phosphorus is 20:1, and the molar ratio of silver to cerium is 15:1). The mixture is then reacted at 60°C for another 3 minutes to obtain a mixed slurry of aluminum phosphate binder and molecular sieve.

[0093] Calcination and molding: Add matrix slurry (obtained by uniformly mixing pseudoboehmite, bentonite, and deionized water with a gel solubility index of 20%) to the above-mentioned aluminum phosphate binder and molecular sieve mixture slurry, and continue high-speed emulsification in a high-shear emulsifier for 2 minutes. Then, immediately export it for spray molding and drying. The spray molding conditions are that the furnace temperature of the spray tower is controlled at 580℃ and the temperature of the spray tail gas is controlled at 160℃. After calcining at 600℃ for 2 hours, the resulting material is a catalytic cracking aid.

[0094] The molar ratio of the metal chelate added in the acid treatment step to the metal chelate added in the mixed slurry step is 1:1.

[0095] The physicochemical and catalytic properties of this catalytic cracking aid are shown in Table 1.

[0096] Example 5

[0097] The catalytic cracking additive provided in this embodiment, based on the total dry weight of the catalytic cracking additive as 100%, contains 45wt% ZSM-5 molecular sieve, 11wt% Y-type molecular sieve, 6wt% metal chelate, 2.6wt% boehmite, 17.4wt% kaolin, and 18wt% binder (P / Al molar ratio of 6:1).

[0098] The specific preparation method is as follows:

[0099] Ammonium exchange: After exchanging ZSM-5 molecular sieve with Si / Al (mol) ratio of 25 and Y-type molecular sieve with ammonium chloride, the molar content of Na2O in the mixed molecular sieve is reduced to below 0.1 wt%.

[0100] Acid treatment: The above-mentioned ammonium-exchanged mixed molecular sieves were mixed with deionized water to obtain a molecular sieve slurry. Then, a mixture of dilute hydrochloric acid and oxalic acid (molar ratio of hydrochloric acid to oxalic acid of 3:1) was added to the molecular sieve slurry. After the acid was added, the pH of the system was 1.0. The temperature was raised to 80°C and the reaction was carried out in a reactor with a reflux device for 10 hours. After the reaction was completed, DOTA chelated lanthanum metal chelate was added. The mixture was stirred at the same temperature for another 0.5 hours. The material obtained after the reaction was dried at 120°C for 12 hours and then calcined at 600°C for 3 hours (100% steam was introduced for the first 120 minutes of calcination and air was introduced for the last 60 minutes of calcination).

[0101] Mixed slurry: The calcined molecular sieve obtained from the acid treatment step is mixed with deionized water, and oxalic acid is added to stabilize the pH of the system at 1.0. The mixture is then added to a high-shear emulsifier, followed by the addition of aluminum oxide and heating to 80°C. After uniform dispersion, phosphoric acid is added in proportion, and the mixture is rapidly reacted at 80°C for 10 minutes. Then, a mixed solution of silver chelated with ethylenediaminetetraacetic acid and cerium chelated with hydroxyethylethylenediaminetriacetic acid is added (the ratio of the total molar amount of silver and cerium to the molar amount of phosphorus is 10:1, and the molar ratio of silver to cerium is 10:1). The mixture is then reacted at 80°C for another 3 minutes to obtain a mixed slurry of aluminum phosphate binder and molecular sieve.

[0102] Calcination and molding: Add matrix slurry (obtained by uniformly mixing boehmite, kaolin, and deionized water with a gel solubility index of 20%) to the above-mentioned aluminum phosphate binder and molecular sieve mixture slurry, and continue high-speed emulsification in a high-shear emulsifier for 2 minutes. Then, immediately export it for spray molding and drying. The spray molding conditions are that the furnace temperature of the spray tower is controlled at 580℃ and the temperature of the spray tail gas is controlled at 160℃. After calcining at 600℃ for 2 hours, the obtained material becomes the catalytic cracking aid.

[0103] The molar ratio of the metal chelate added in the acid treatment step to the metal chelate added in the mixed slurry step is 1:1.

[0104] The physicochemical and catalytic properties of this catalytic cracking aid are shown in Table 1.

[0105] Comparative Example 1

[0106] The catalytic cracking additive provided in this comparative example contains 70 wt% molecular sieves, based on 100% of the total dry weight of the additives. Among them, ZSM-5 zeolite (Si / Al (mol) ratio of 50) content is 49 wt%, Beta molecular sieve content is 21 wt%, kaolinite content is 10 wt%, boehmite content is 4 wt% (colloidal index 99%), additives (based on P2O5) content is 15 wt%, and La2O3 content is 1.0 wt%.

[0107] Preparation of phosphorus aluminum sol binder: 4 wt% of boehmite (dry basis) and a certain amount of deionized water were mixed and stirred. Then, 15 wt% (calculated as P2O5) and 85 wt% concentrated phosphoric acid were added to the slurry. A certain amount of hydrochloric acid was then added to control the pH of the system to 1.5, thus obtaining a colorless and transparent phosphorus aluminum sol.

[0108] Preparation of mixed molecular sieve slurry: 70 wt% of molecular sieve by dry weight is mixed with a certain amount of deionized water, stirred evenly, and then 1 wt% of La(NO3)3 solution (calculated as La2O3) by dry weight is added to prepare mixed molecular sieve slurry.

[0109] Preparation of the additive: Under stirring, 10 wt% kaolin (dry weight) and a certain amount of water were mixed and slurried. Phosphorus aluminum sol was added, and stirring continued for 0.5 h. Then, the above-mentioned mixed molecular sieve slurry was added, and stirring continued for 0.5 h. The resulting slurry had a solid content of 38 wt%. After homogenization, the slurry was spray-molded and calcined at 600℃ for 2 h to obtain the additive.

[0110] Comparative Example 2

[0111] 80g of NH4Cl was dissolved in 1000g of water. 100g (dry basis) of crystallized ZSM-5 molecular sieve (synthesized via amine method, SiO2 / Al2O3 = 170) was added to this solution. After exchange at 85℃ for 0.5h, the mixture was filtered to obtain a filter cake. 8.9g of NH4H2PO4 was dissolved in 60g of water and mixed with the filter cake for impregnation and drying. 31.9g of FeSO4·6H2O was dissolved in 90g of water and mixed with the above sample for impregnation and drying. The mixture was then calcined at 600℃ for 2 hours to obtain the molecular sieve. Elemental analysis showed the chemical composition to be 0.1Na2O·0.94Al2O3·5.1P2O5·10.1Fe2O3·84SiO2.

[0112] 0.37 kg of aluminum hydroxide powder (containing 0.28 kg of Al2O3), 0.52 kg of rettore (0.40 kg dry basis) and 4.31 kg of decationized water were mixed into a slurry for 30 minutes. While stirring, 2.14 kg of phosphoric acid (containing 1.32 kg of phosphorus pentoxide) was added to the slurry at a rate of 0.07 kg phosphoric acid / min / kg alumina source. The temperature was raised to 70°C and then reacted at this temperature for 45 minutes to obtain a clay-containing phosphorus aluminum inorganic binder.

[0113] The above-mentioned molecular sieve, kaolin (78 wt% solid content), diatomaceous earth, and pseudoboehmite (60% solid content, industrial product produced by Shandong Aluminum Plant) were added to decationized water and water glass (industrial product produced by Qilu Petrochemical Catalyst Plant, with 28.9 wt% SiO2 content and 8.9 wt% Na2O content). The mixture was slurried for 120 minutes. Hydrochloric acid was added to adjust the pH of the slurry to 3.0, and the mixture was slurried for 45 minutes. Diammonium hydrogen phosphate solid was added, and then a phosphorus aluminum inorganic binder containing clay was added to the slurry. The mixture was stirred for 30 minutes to obtain a slurry with a solid content of 38 wt%. The obtained slurry was then spray-dried to obtain microspheres with an average particle diameter of 65 micrometers. The microspheres were calcined at 500℃ for 1 hour, then mixed with a 1.5 wt% FeCl3·6H2O aqueous solution and reacted at 60℃ for 20 minutes. The mixture was filtered, dried, and then calcined at 500℃ for 2 hours to obtain a catalytic cracking aid.

[0114] In the above-mentioned collodion soil, the content of quartz sand is <3.5wt%, Al2O3 is 39.0wt%, Fe2O3 is 2.0wt%, Na2O is 0.03wt%, and the solid content is 77wt%.

[0115] Comparative Example 3

[0116] In this comparative example, the content of each component in the catalytic cracking aid is the same as in Example 5, and the preparation method is similar to that in Example 5, except that the acid treatment step is omitted, and the metal chelates are added in the calcination and shaping step. The specific preparation process is as follows:

[0117] Ammonium exchange: After exchanging ZSM-5 molecular sieve with Si / Al (mol) ratio of 25 and Y-type molecular sieve with ammonium chloride, the molar content of Na2O in the mixed molecular sieve is reduced to below 0.1 wt%.

[0118] Mixed slurry: The ammonium-exchanged molecular sieve was mixed with deionized water, and oxalic acid was added to stabilize the pH of the system at 1.0. The mixture was then added to a high-shear emulsifier, followed by the addition of aluminum oxide and heating to 80°C. After uniform dispersion, phosphoric acid was added in proportion, and the mixture was kept at 80°C for a rapid reaction of 10 min. Then, a mixed solution of DOTA-chelated lanthanum metal chelate, ethylenediaminetetraacetic acid-chelated silver, and hydroxyethylethylenediaminetriacetic acid-chelated cerium (the ratio of the total molar amount of silver and cerium to the molar amount of phosphorus was 10:1, and the molar ratio of silver to cerium was 10:1) was added, and the mixture was allowed to react at 80°C for another 3 min to obtain a mixed slurry of aluminum phosphate binder and molecular sieve.

[0119] Calcination and molding: Add matrix slurry (obtained by uniformly mixing boehmite, kaolin, and deionized water with a gel solubility index of 20%) to the above-mentioned aluminum phosphate binder and molecular sieve mixture slurry, and continue high-speed emulsification in a high-shear emulsifier for 2 minutes. Then, immediately export it for spray molding and drying. The spray molding conditions are that the furnace temperature of the spray tower is controlled at 580℃ and the temperature of the spray tail gas is controlled at 160℃. After calcining at 600℃ for 2 hours, the obtained material becomes the catalytic cracking aid.

[0120] The physicochemical and catalytic properties of this additive are shown in Table 1.

[0121] Comparative Example 4

[0122] This comparative example is similar to Example 5, except that lanthanum nitrate, silver nitrate, and cerium nitrate are used in this comparative example instead of the corresponding metal chelates in Example 5. Specifically, the ratio of the molar mass of lanthanum nitrate added in the acid treatment step to the total molar mass of silver nitrate and cerium nitrate added in the slurry mixing step is 1:1. Based on the total dry weight of the catalytic cracking aid as 100%, the total content of lanthanum nitrate, silver nitrate, and cerium nitrate is 6 wt%.

[0123] The physicochemical and catalytic properties of the catalytic cracking aid prepared in this comparative example are shown in Table 1.

[0124] Comparative Example 5

[0125] This comparative example is similar to Example 5, except that the gel solubility index of the pseudoboehmite used is different. The gel solubility index of the pseudoboehmite used in this comparative example is 99%.

[0126] The physicochemical and catalytic properties of the catalytic cracking aid prepared in this comparative example are shown in Table 1.

[0127] Comparative Example 6

[0128] This comparative example is similar to Example 5, except that the apparatus used in the mixing slurry and calcination molding steps is different. In this comparative example, a stirred reactor is used instead of a high-shear emulsifier, and the working time is extended accordingly until the mixture is uniform.

[0129] The physicochemical and catalytic properties of the catalytic cracking aid prepared in this comparative example are shown in Table 1.

[0130] Comparative Example 7

[0131] The catalytic cracking additive provided in this comparative example, based on the total weight of the catalytic cracking additive on a dry basis of 100%, contains 45 wt% ZSM-5 molecular sieve, 11 wt% Y-type molecular sieve, 6 wt% metal chelate, 2.6 wt% pseudoboehmite, 17.4 wt% kaolin, and 18 wt% binder (P / Al molar ratio of 6:1).

[0132] The specific preparation method is as follows:

[0133] Ammonium exchange: After exchanging ZSM-5 molecular sieve with Si / Al (mol) ratio of 25 and Y-type molecular sieve with ammonium chloride, the molar content of Na2O in the mixed molecular sieve is reduced to below 0.1 wt%.

[0134] Acid treatment: The above-mentioned ammonium-exchanged mixed molecular sieve is mixed with deionized water to obtain a molecular sieve slurry. Then, a mixture of dilute hydrochloric acid and oxalic acid (molar ratio of hydrochloric acid to oxalic acid is 3:1) is added to the molecular sieve slurry. After the acid is added, the pH of the system is 1.0. The temperature is raised to 80°C and reacted in a reactor with a reflux device for 10 hours. After the reaction is completed, the mixture is stirred at the same temperature for another 0.5 hours. The material obtained after the reaction is dried at 120°C for 12 hours and then calcined at 600°C for 3 hours (100% steam is introduced for the first 120 minutes of calcination and air is introduced for the last 60 minutes of calcination).

[0135] Mixed slurry: The calcined molecular sieve obtained from the acid treatment step is mixed with deionized water, and oxalic acid is added to stabilize the pH of the system at 1.0. The mixture is then added to a high-shear emulsifier, followed by the addition of aluminum oxide and heating to 80°C. After uniform dispersion, phosphoric acid is added in proportion, and the mixture is rapidly reacted at 80°C for 10 minutes. Then, a mixed solution of DOTA-chelated lanthanum metal chelate, ethylenediaminetetraacetic acid-chelated silver, and hydroxyethylethylenediaminetriacetic acid-chelated cerium is added (the ratio of the total molar amount of silver and cerium to the molar amount of phosphorus is 10:1, and the molar ratio of silver to cerium is 10:1; the molar ratio of DOTA-chelated lanthanum metal chelate to (ethylenediaminetetraacetic acid-chelated silver and hydroxyethylethylenediaminetriacetic acid-chelated cerium) is 1:1). The mixture is then reacted at 80°C for another 3 minutes to obtain a mixed slurry of aluminum phosphate binder and molecular sieve.

[0136] Calcination and molding: Add matrix slurry (obtained by uniformly mixing boehmite, kaolin, and deionized water with a gel solubility index of 20%) to the above-mentioned aluminum phosphate binder and molecular sieve mixture slurry, and continue high-speed emulsification in a high-shear emulsifier for 2 minutes. Then, immediately export it for spray molding and drying. The spray molding conditions are that the furnace temperature of the spray tower is controlled at 580℃ and the temperature of the spray tail gas is controlled at 160℃. After calcining at 600℃ for 2 hours, the obtained material becomes the catalytic cracking aid.

[0137] Table 1 Physicochemical and reactive properties of the additives

[0138]

[0139]

[0140] As can be seen from the data in the table above, compared with the comparative example, the catalytic cracking additive provided by the present invention has better overall performance: it has higher wear resistance, larger pore volume and higher molecular sieve content, and the yield of the target product of catalytic cracking is higher.

[0141] 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 high-strength, large-pore-volume catalytic cracking additive, characterized in that, The invention comprises molecular sieves, a matrix, a binder, and a metal chelate, wherein the matrix is ​​composed of a γ-alumina precursor with a colloidal index ≤50% and clay, and the binder is prepared from a phosphorus-containing compound and an aluminum-containing compound. The molecular sieves having an MFI structure and a pore diameter of less than 0.7 nm account for 50 wt% to 100 wt% of the total molecular sieves. The binder, the metal chelate, and the matrix are all mixed in a high-shear emulsifier; The metal chelate is selected from at least one of phosphonic acid metal chelates, aminocarboxylic acid metal chelates, hydroxyaminocarboxylic acid metal chelates, carboxylic acid metal chelates, and carbonyl metal chelates; The metal in the metal chelate is at least one of rare earth metal ions, transition metal ions, alkali metal ions, and alkaline earth metal ions. The preparation method of the high-strength, large-pore-volume catalytic cracking additive includes the following steps: Acid treatment: Molecular sieves with Na2O content ≤0.1wt% are mixed with deionized water to form a molecular sieve slurry. A mixture of organic and inorganic acids is added until the pH of the molecular sieve slurry is ≤2.0 and the reaction is carried out. After the reaction is completed, a metal chelate is added and the reaction is carried out. After the reaction is completed, the slurry is dried and calcined to obtain the acid-treated molecular sieve. Mixed slurry: After mixing the acid-treated molecular sieve with deionized water, the pH of the slurry is adjusted to ≤2.0 and added to a high-shear emulsifier. Then, aluminum-containing compounds and phosphorus-containing compounds are added, along with metal chelates. The mixture is stirred evenly to obtain a mixed slurry of aluminum phosphate binder and molecular sieve. Calcination and molding: Add matrix slurry to the mixed slurry of aluminum phosphate binder and molecular sieve, and continue to mix in a high-shear emulsifier for 5 minutes. Then, perform spray molding and drying, and calcination to obtain the high-strength, large-pore-volume catalytic cracking aid.

2. The high-strength, large-pore-volume catalytic cracking additive as described in claim 1, characterized in that, The metal chelate is a mixture of at least two metal chelates or a multi-metal chelate containing at least two metals.

3. The high-strength, large-pore-volume catalytic cracking additive as described in claim 1 or 2, characterized in that, The metal in the metal chelate is a transition metal ion or a rare earth metal ion.

4. The high-strength, large-pore-volume catalytic cracking additive as described in claim 3, characterized in that, The ratio of the total molar amount of metal ions in the metal chelate to the molar amount of phosphorus in the phosphorus-containing compound is 5~20:

1.

5. The high-strength, large-pore-volume catalytic cracking additive as described in claim 1, characterized in that, The molar ratio of phosphorus in the phosphorus-containing compound to aluminum in the aluminum-containing compound is 2 to 10:

1.

6. The high-strength, large-pore-volume catalytic cracking additive as described in claim 1, characterized in that, The colloidal index of the γ-alumina precursor is 20%~30%; The mass ratio of the γ-alumina precursor to the clay is 1:0.5~15.

7. The high-strength, large-pore-volume catalytic cracking additive as described in claim 1, characterized in that, Based on the total dry weight of the catalytic cracking aid as 100%, the content of the molecular sieve is 20wt%~70wt%, the content of the matrix is ​​10wt%~40wt%, the content of the binder is 10wt%~30wt%, and the content of the metal chelate is 2wt%~10wt%.

8. The high-strength, large-pore-volume catalytic cracking additive as described in claim 1, characterized in that, The molar ratio of the metal chelate added in the acid treatment step to the metal chelate added in the bonding and molding step is 1:1~4.

9. The high-strength, large-pore-volume catalytic cracking additive as described in claim 1, characterized in that, In the acid treatment step, 100% steam is introduced during the first two-thirds of the roasting time, and air is introduced during the last one-third of the time.

10. The high-strength, large-pore-volume catalytic cracking additive as described in claim 3, characterized in that, The molar ratio of the transition metal ion to the rare earth metal ion in the metal chelate is 5~15:

1.

11. The high-strength, large-pore-volume catalytic cracking additive as described in claim 5, characterized in that, The molar ratio of phosphorus in the phosphorus-containing compound to aluminum in the aluminum-containing compound is 4~8:

1.

12. The high-strength, large-pore-volume catalytic cracking additive as described in claim 6, characterized in that, The XRD patterns of the γ-alumina precursor show characteristic peaks around 2θ of 14°, 28°, 38°, and 49°.

13. The high-strength, large-pore-volume catalytic cracking additive as described in claim 6, characterized in that, The mass ratio of the γ-alumina precursor to the clay is 1:2~9.

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