Process for the preparation of a catalytic cracking propylene promoter

Abstract

The application provides a preparation method of a catalytic cracking propylene aid, a Y-type molecular sieve filter cake layer is first formed, then ZSM-5 molecular sieve exchanged by containing phosphorus wastewater is loaded on the Y-type molecular sieve filter cake, surplus phosphorus in the filtrate is recovered by the Y-type molecular sieve filter cake layer, the loss of phosphorus is reduced, meanwhile, the surplus phosphorus can also modify the Y-type molecular sieve, and the thermal stability and the hydrothermal stability of the Y-type molecular sieve are simultaneously improved. The added humic acid is a multi-element organic complex, has the function of fixing phosphorus elements, makes the phosphorus elements not easy to flow away with the filtrate, and further improves the phosphorus utilization rate. The preparation method of the catalytic cracking aid provided by the application recycles the phosphorus-containing wastewater of the aid microspheres for the molecular sieve ion exchange process, can effectively reduce the water consumption and the consumption of the phosphorus-containing exchange liquid in the aid production process, and is favorable for reducing the production cost of the aid.

Description

Technical Field

[0001] This invention relates to the field of additive preparation, and specifically to a method for preparing an additive for catalytic cracking of propylene. Background Technology

[0002] Propylene is an extremely important organic chemical raw material, mainly used in the production of polypropylene, acrylonitrile, propylene oxide, acrylic acid, cumene, and other chemicals. With the rapid development of the petrochemical industry, the demand for propylene is constantly increasing, and currently, my country's propylene supply is insufficient to meet demand. There are various process schemes for producing propylene in the petrochemical industry, such as the traditional naphtha steam cracking method, the translocation reaction technology of ethylene and butene, the butene disproportionation reaction (CN1618512A, CN1618515A), propane dehydrogenation technology (such as CN1073893A), methanol-to-propylene technology, and catalytic cracking processes. Comparative analysis shows that the fluidized catalytic cracking (FCC) process for producing propylene has significant advantages such as lower investment, wider raw material adaptability, and lower cost, and is therefore receiving increasing attention (US5318696A, US5997728A, US5236880A, US5472594A, CN1465527A, CN1796496A, CN1854254A). Adding a co-catalyst to increase propylene production during catalytic cracking is widely used due to its advantages of simple operation, flexible reaction, and minimal impact on the overall process.

[0003] USP 5,997,728 discloses a method for catalytic cracking of heavy feedstocks using a catalytic cracking additive containing shape-selective zeolite. The additive is formed by adding 12–40 wt% ZSM-5 zeolite to an amorphous matrix, with a content of at least 10 wt% in the catalytic cracking system, and ensuring that the proportion of ZSM-5 in the catalyst is not less than 3 wt%. This method can significantly improve the yield of low-carbon olefins.

[0004] CN111760588A discloses a propylene-enhancing catalytic cracking additive, characterized in that, based on 100% dry weight of the additive, it contains 10-60 wt% ZSM-5 molecular sieve, 5-30 wt% binder, 0.5-5 wt% phosphorus-containing cationic compound (calculated as P2O5), and 20-80 wt% clay. This additive, when combined with the main catalyst for catalytic cracking, can significantly increase the yield of liquefied petroleum gas and propylene in the catalytic cracking reaction.

[0005] CN102188992B discloses a catalytic cracking additive for increasing propylene production in a refinery's FCC unit and its preparation method. The catalytic cracking additive comprises 20-35 parts by weight of a binder, 5-10 parts by weight of a sol, 2-8 parts by weight of an oxide, and the balance being a high-silica ZSM-5 molecular sieve. The binder is alumina or silica. The sol is an acidic silica sol. The oxide is a metal oxide or a non-metal oxide. This catalytic cracking additive for increasing propylene production, when used in a catalytic cracking FCC unit, can significantly increase the propylene concentration in the liquefied petroleum gas (LPG) without increasing the LPG yield.

[0006] CN101450321A discloses a catalytic cracking additive for increasing propylene production. Based on the total weight of the additive, it contains 10-40 wt% silica binder (based on silica), 10-30 wt% aluminum binder (based on alumina), 0.5-35 wt% molecular sieve, 5-60 wt% clay, and 0.5-2 wt% rare earth oxides. The molecular sieve includes a type-selective molecular sieve. The additive incorporates an anti-coagulation and polymerization inhibitor during preparation, and the silica binder is introduced in two steps. This additive exhibits strong heavy oil cracking capability and, when used in catalytic cracking, results in high propylene yield.

[0007] CN102872902A discloses a catalytic cracking additive for increasing propylene production. The additive, by total weight, comprises: 50-75% high-silica zeolite, 20-45% binder, and 1-5% oxide. The high-silica zeolite is a ZSM-5 type hydrogen-form zeolite with a SiO2 to Al2O3 molar ratio of 100-500. The binder is one or a combination of kaolin, alumina, silica, diatomaceous earth, and sol. The oxide is one or a combination of alkali metal oxides, rare earth metal oxides, and non-metal oxides. When used in a catalytic cracking FCC unit, this additive, when mixed with the FCC catalyst, can significantly increase the propylene concentration in the liquefied petroleum gas (LPG) without increasing the LPG yield.

[0008] CN112387302A discloses a catalytic cracking additive, its preparation method, its application, and a method for catalytic cracking of hydrocarbon oils. The catalytic cracking additive comprises high-silica zeolite, mesoporous silica, a binder, and a modifier; wherein the high-silica zeolite is a hydrogen-form zeolite with an MFI framework structure and a silicon-to-aluminum molar ratio (SiO2 / Al2O3) of not less than 100; the mesoporous silica is a one-dimensional, through-pore mesoporous silica material; and the modifier is selected from at least one of alkaline earth metal oxides, rare earth metal oxides, and non-metallic oxides. When used in the catalytic cracking process of hydrocarbon oils, this catalytic cracking additive can increase the propylene concentration in the liquefied petroleum gas (LPG) while ensuring the yield of LPG from catalytic cracking.

[0009] CN112570017 A catalytic cracking catalyst and its preparation method, comprising: mixing and slurrying five-membered ring zeolite, optionally octahedral zeolite, natural minerals, zirconium-aluminum composite sol and other inorganic oxide binders, and spray drying; wherein, the zirconium-aluminum composite sol preparation method comprises the following steps: (1) mixing zirconium dioxide precursor and water, and exchanging with an anion exchange resin to obtain a first mixture, wherein the pH value of the first mixture is 2-5; (2) reacting alumina precursor, optionally water, acid and the first mixture to form a second mixture, wherein the pH value of the second mixture is preferably 2-5; and optionally (3) mixing the second mixture with a surfactant. This catalyst has good strength and can be used for heavy oil catalytic cracking. It can have higher cracking activity than existing five-membered ring zeolite cracking catalysts, higher ethylene and propylene selectivity, and can also have higher liquefied gas yield and / or higher propylene yield.

[0010] Phosphorus modification can significantly improve the cracking activity and stability of additives containing ZSM-5 zeolite.

[0011] USP 6566293 discloses a cracking catalyst using phosphorus-modified ZSM-5 zeolite. The preparation of the phosphorus-modified ZSM-5 involves dispersing the zeolite in an aqueous solution of a phosphorus-containing compound at a pH above 4.5, loading the zeolite with at least 10 wt% phosphorus (based on P2O5), then slurrying it with a matrix and a non-MFI structured zeolite component, followed by spray drying to form the catalyst. The resulting catalyst exhibits high yields of low-carbon olefins in catalytic cracking.

[0012] CN1796497 discloses a catalytic cracking additive for increasing propylene production. The additive, on a dry basis, comprises 10-65 wt% modified ZSM-5 molecular sieve, 0-60 wt% clay, 15-70 wt% inorganic oxide binder, 0.5-10 wt% magnesium additive, and 0.5-15 wt% zinc additive, wherein the modified ZSM-5 molecular sieve is modified with phosphorus. When applied to the catalytic cracking process, this additive can significantly increase the propylene concentration in liquefied petroleum gas (LPG) while simultaneously increasing the yield of LPG and improving the octane number of gasoline.

[0013] CN1049406C discloses a zeolite containing phosphorus and rare earth elements and possessing an MFI structure. Its anhydrous chemical composition is aRE₂O₃·bNa₂O·Al₂O₃·cP₂O₅·dSiO₂, where a = 0.01-0.25, b = 0.005-0.02, c = 0.2-1.0, and d = 35-120. This zeolite exhibits excellent hydrothermal activity and stability, as well as good selectivity for low-carbon olefins, in high-temperature hydrocarbon conversion.

[0014] CN1465527A discloses a phosphorus- and transition metal-containing MFI structure zeolite. The anhydrous chemical formula of this zeolite, based on the mass of oxides, is (0-0.03)Na₂O·(0.5-5)Al₂O₃·(1.3-10)P₂O₅·(0.7-15)M₂O₃·(70-97)SiO₂, where M is selected from one of the transition metals Fe, Co, and Ni. When applied to the catalytic cracking process of petroleum hydrocarbons, this zeolite can improve the yield and selectivity of C₂-C₄ olefins and exhibit higher liquefied petroleum gas (LPG) yield.

[0015] In addition to phosphorus modification of ZSM-5 zeolite, there are also reports that introducing phosphorus compounds into the matrix can improve the selectivity of the additives for propylene.

[0016] USP2002 / 0003103A1 discloses a catalytic cracking process for increasing propylene yield. The catalyst composition used contains macroporous USY zeolite, mesoporous zeolites such as ZSM-5, and an inorganic binder component with cracking properties. The inorganic binder component contains phosphorus, with a P / Al ratio of 0.1-10. This process can significantly increase the production of low-carbon olefins, especially propylene yield.

[0017] USP2002 / 0049133A1 discloses a catalyst with high zeolite content and high wear resistance. The catalyst contains 30-85 wt% ZSM-5 zeolite, 6-24 wt% phosphorus (as P2O5), and less than 10 wt% Al2O3 and the balance clay and other components, wherein the phosphorus is present in the matrix. This catalyst can increase the yield of light olefins, especially propylene, in catalytic cracking processes.

[0018] CN 100537030C discloses a catalytic additive for increasing the propylene concentration in catalytic cracking liquefied petroleum gas (LPG). Based on the weight of the additive, it contains 10–65 wt% MFI-structured zeolite, 0–20 wt% non-MFI-structured zeolite, 0–60 wt% clay, 15–60 wt% inorganic oxide binder (based on oxides), 0.5–15 wt% copper additive (based on CuO), and 2–25 wt% phosphorus additive (based on P2O5). When applied to the catalytic cracking process of petroleum hydrocarbons, this catalytic additive significantly increases the propylene concentration in LPG while simultaneously increasing the yield of LPG and improving the octane number of gasoline produced by catalytic cracking.

[0019] CN102049284A discloses a catalytic cracking propylene additive, characterized in that, based on 100% of the total additive weight, it 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 P, calculated as P2O5, of 5.0-20.0% by weight, preferably 7.0-15.0% by weight, and La2O3 content is 0-1.0% by weight. Aluminum phosphate sol is used as a binder, which improves the abrasion resistance of the additive, increases the solid content of the spray slurry, and avoids chlorine content in the spray slurry and the additive. The prepared catalytic cracking propylene additive exhibits significantly improved activity. When used in combination with the main catalyst, it causes minimal reduction in the activity of the main catalyst, improves product distribution, and demonstrates good selectivity for dry gas and coke, while simultaneously increasing propylene yield.

[0020] CN107185586B discloses a catalytic cracking additive that produces high yields of propylene and isopentene, its preparation method, and its application. The catalytic cracking additive, on a dry basis, comprises, based on the total weight of the additive, 15-45 wt% of alkali-modified ZSM-5 molecular sieve; 1-20 wt% of USY molecular sieve; 1-10 wt% of β-zeolite; 3-25 wt% of P2O5; 3-25 wt% of inorganic oxides; and the balance being clay. This catalytic cracking additive can promote the shape-selective isomerization cracking reaction of C8 and above gasoline components in catalytic cracked gasoline, simultaneously increasing the yields of propylene and isopentene, and increasing the propylene content (Δpropylene / ΔLPG) in the incremental LPG.

[0021] CN101474573B discloses a high-propylene-yield catalytic cracking additive and its preparation method, characterized by comprising the following components (wt%): 10-60 parts of ZSM-5 molecular sieve modified with multi-component organic acids, 10-40 parts of Al2O3, 1-20 parts of P (calculated as elemental P), 1-15 parts of rare earth elements (calculated as RE2O3), and 5-40 parts of clay. This additive, when used in combination with various catalytic cracking catalysts, is suitable for heavy hydrocarbon oils and catalytic cracking feedstock hydrocarbon oils from various sources; it exhibits good selectivity for propylene, high catalytic cracking conversion rate, high liquefied petroleum gas (LPG) yield, and high propylene content in the LPG; simultaneously, it does not increase dry gas or coke production. The preparation method includes the following steps: a. Preparation of aluminum phosphate solution: According to the ratio of P (calculated as P2O5):Al2O3 = 1-5:1 (mol ratio), the phosphorus source compound and hydrated alumina are dissolved separately in deionized water, mixed and prepared into an aluminum phosphate gel with a solid content of 20-40 wt%. Under stirring, the gel is dissolved for 1-5 hours at a temperature of 20℃-60℃ to obtain aluminum phosphate solution; b. Preparation of ZSM-5 molecular sieve modified with polybasic organic acid: According to the formula, ZSM-5 molecular sieve is added to water to prepare a slurry with a solid content of 10%. Polybasic organic acid is added while stirring. The reaction is carried out at a temperature of 20-90℃ for 1-5 hours. After filtration, the filter cake is washed with deionized water until the filtrate is neutral; c. 1. Add water to the ZSM-5 molecular sieve filter cake modified with multi-organic acids prepared in step b and slurry it. Then add rare earth metal solution according to the formula, stir and react for 30-120 minutes, add ammonia water to adjust the pH value until the rare earth molecular sieve in the solution precipitates, and mix and slurry; d. Mixing and slurrying: Put the phosphorus aluminum glue prepared in step a, the molecular sieve modified with multi-organic acids in step b and rare earth modified in step c, clay and aluminum sol into a mixing and slurrying tank, mix and slurry for 1-2 hours, add hydrochloric acid under stirring to adjust the pH value to 3.0, and continue slurrying for 30-60 minutes; e. Spray dry and shape; f. Wash and dry: Wash with deionized water until the pH value of the washing water is between 6 and 7, and dry at 80-120℃.

[0022] CN103254925B discloses a catalytic cracking additive for increasing propylene production. By total weight, the additive 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. This catalytic cracking additive, when applied to the catalytic cracking process of petroleum hydrocarbons, can significantly reduce the loss of catalytic gasoline components while increasing propylene yield and improving gasoline octane number. The preparation method includes the following steps: (1) Preparation of aluminum phosphate oxide: according to the weight ratio of P2O5 to Al2O3 (2.5-3.0):1, aluminum sol and ammonium phosphate are added to a certain amount of chemical water to prepare aluminum phosphate glue with a solid content of 20-40%; (2) Preparation of aluminum silicate glue: according to the weight ratio of SiO2 to Al2O3 2:1, aluminum sulfate solution is slowly added to water glass solution under stirring; (3) Mixing and pulping: aluminum phosphate glue is added to pulping tank, and added HZSM-5 molecular sieve, stir for 40-60 minutes, add kaolin, slurry for 60 minutes, add the prepared silica-alumina glue, and continue slurrying for 30-60 minutes; (4) Drying and molding: use spray drying molding method; (5) Calcination: calcinate at 400-600℃ for 4 hours; (6) Washing and drying: wash once with chemical water at 60℃, water / agent ratio of (5-10):1, and dry at 110-120℃ after washing to obtain the required additive.

[0023] In the existing catalytic cracking propylene additive production process, the additive needs to be washed multiple times with water after molding. The total phosphorus content (calculated as P) of the wastewater after additive washing exceeds the limit of the "Integrated Wastewater Discharge Standard" (GB8978-1996) (Grade I standard: 0.5 mg / L; Grade II standard: 1.0 mg / L). It is necessary to spend a lot of money to treat the phosphorus-containing wastewater before it can be discharged. Otherwise, it will cause serious pollution to the environment.

[0024] Current technologies mainly focus on improving the cracking performance of propylene additives in catalytic cracking and methods for removing phosphorus from phosphorus-containing wastewater, while there are no reports on the recycling and utilization of phosphorus-containing wastewater from propylene additives. Existing technologies all use adsorbents to adsorb phosphorus to meet emission standards. This operation requires prolonged contact between the adsorbent and the wastewater, and the adsorbent needs periodic regeneration, which cannot meet the continuous production requirements of propylene additive preparation and seriously affects the production capacity of propylene additives.

[0025] Therefore, how to effectively improve the phosphorus utilization rate in the propylene additive production process and reduce the discharge of phosphorus-containing wastewater is an important measure for catalyst manufacturers to reduce costs and increase efficiency, and it is also one of the key research topics for catalyst manufacturers. Summary of the Invention

[0026] The purpose of this invention is to provide a method for preparing propylene additives for catalytic cracking, which solves the problem of severe phosphorus pollution during the production of propylene additives for catalytic cracking. It requires no additional investment, achieves direct discharge of wastewater on existing additive production equipment, and ensures green production of additives.

[0027] To achieve the above objectives, the present invention provides a method for preparing a catalytic cracking propylene additive, comprising the following steps:

[0028] 1) Y-type molecular sieve, humic acid and water are slurried to obtain Y-type molecular sieve slurry, and the Y-type molecular sieve slurry is filtered to form Y-type molecular sieve filter cake layer. The dry weight ratio of humic acid to Y-type molecular sieve is 0.001-0.05.

[0029] 2) ZSM-5 molecular sieve is slurried with phosphorus-containing wastewater to obtain ZSM-5 molecular sieve slurry. The ZSM-5 molecular sieve slurry is filtered through a Y-type molecular sieve filter cake layer to form a ZY composite filter cake layer. The ZY composite filter cake layer is ion exchanged with a first phosphorus-containing exchange solution and then washed with water to obtain a ZY composite molecular sieve filter cake. The amount of the first phosphorus-containing exchange solution used is 0.005-0.15 by weight of the dry basis of ZSM-5 molecular sieve (calculated as P).

[0030] 3) The ZY composite molecular sieve filter cake, inorganic oxide, clay, binder and water are mixed and pulped, spray dried and shaped, and calcined to obtain auxiliary microspheres. The auxiliary microspheres are mixed with water and pulped, then filtered to form microsphere filter cake. The microsphere filter cake is ion exchanged with a second phosphorus-containing exchange solution, then washed with water and dried to obtain catalytic cracking propylene auxiliary agent. The amount of the second phosphorus-containing exchange solution and the weight ratio of the dry basis of the microspheres is 0.005-0.10 (calculated as P).

[0031] In this invention, the conditions for mixing the Y-type molecular sieve with water in step 1) are well known to those skilled in the art, and the content of the Y-type molecular sieve in the slurry is generally 100-300 g / L. The temperature of the slurry can be 10-100℃, preferably 50-90℃. The conditions for spray drying and calcination curing in step 3) are well known to those skilled in the art, such as a drying temperature of room temperature to 200℃, preferably 100-150℃, a calcination curing temperature of 300-600℃, preferably 400-500℃, and a calcination time of 10-200 minutes, preferably 30-60 minutes.

[0032] The method for preparing the catalytic cracking propylene additive of the present invention wherein the Y-type molecule is selected from one or more of USY, REY, HY, REHY, NH4Y and REUSY.

[0033] The preparation method of the catalytic cracking propylene additive of the present invention, wherein the humic acid is selected from one or more of fulvic acid, brown humic acid and black humic acid.

[0034] The method for preparing the catalytic cracking propylene additive of the present invention uses ZSM-5 molecular sieves which can be selected from ZSM-5 molecular sieves with different silicon-to-aluminum ratios, or can be ZSM-5 molecular sieves modified with metal ions. Preferably, the metal ions are rare earth ions.

[0035] In the preparation method of the catalytic cracking propylene additive of the present invention, the mass ratio of phosphorus-containing wastewater to ZSM-5 molecular sieve is 2-10, preferably 3-6.

[0036] The preparation method of the catalytic cracking propylene additive of the present invention, wherein the phosphorus-containing wastewater is the filtrate collected after ion exchange of the microsphere filter cake with the second phosphorus-containing exchange liquid in step 3).

[0037] The preparation method of the catalytic cracking propylene additive of the present invention, wherein the first phosphorus-containing exchange liquid and the second phosphorus-containing exchange liquid are one or more of ammonium phosphate solution, diammonium hydrogen phosphate solution, ammonium dihydrogen phosphate solution and phosphoric acid.

[0038] The preparation method of the catalytic cracking propylene additive of the present invention is wherein the first phosphorus-containing exchange liquid is prepared by preparing the filtrate collected after ion exchange of the microsphere filter cake with the second phosphorus-containing exchange liquid in step 3).

[0039] The method for preparing the catalytic cracking propylene additive of the present invention comprises: the inorganic oxide being one or more of rare earth oxides, magnesium oxides, and silicon oxides; the clay being one or more of kaolin, halloysite, and montmorillonite; and the binder being one or more of alumina sol, silica sol, and boehmite.

[0040] The preparation method of the catalytic cracking propylene additive of the present invention includes steps 1) and 2) performed on a first horizontal belt filter, the first horizontal bag filter including a Y-type molecular sieve filter cake forming zone, a ZMS-5 molecular sieve filter cake forming zone, a phosphorus exchange zone and a water washing zone connected in series; and step 3) performed on a second horizontal belt filter, the second horizontal belt filter including a microsphere filter cake forming zone, a phosphorus exchange zone and a metal ion exchange zone connected in series.

[0041] Beneficial effects of this invention:

[0042] The present invention provides a method for preparing propylene catalytic cracking additives. First, a Y-type molecular sieve filter cake layer is formed. Then, a ZSM-5 molecular sieve, after being exchanged with phosphorus-containing wastewater, is loaded onto the Y-type molecular sieve filter cake. Excess phosphorus in the filtrate is adsorbed and recovered through the Y-type molecular sieve filter cake layer, reducing phosphorus loss. Simultaneously, excess phosphorus can also modify the Y-type molecular sieve, improving its thermal and hydrothermal stability. The humic acid added in this invention is a multi-component organic complex with phosphorus-fixing capabilities, making it less likely for phosphorus to be lost with the filtrate, further improving phosphorus utilization. The method for preparing propylene catalytic cracking additives provided by this invention recovers phosphorus-containing wastewater from the additive microspheres for use in the molecular sieve ion exchange process, effectively reducing water consumption and phosphorus-containing exchange solution consumption in the additive production process, thus reducing the production cost of the additive. Therefore, compared with existing technologies, the method for preparing propylene catalytic cracking additives provided by this invention requires no additional investment, can meet the direct discharge requirements of wastewater on existing production equipment, and has a simple operation process, providing technical support for green production and energy conservation in catalyst enterprises. Attached Figure Description

[0043] Figure 1 This is a flowchart of the phosphorus exchange process of the molecular sieve in this invention;

[0044] Figure 2 This is a flowchart of the phosphorus exchange process of the microspheres used as an adjuvant in this invention.

[0045] In the attached figures, the following labels are used:

[0046] Pulping tanks 1, 5, 15, and 16;

[0047] Pipelines 2, 6, 10, 13, 17, 21, and 25;

[0048] 3. 18 filter cloth;

[0049] 4Y type molecular sieve filter cake forming zone

[0050] 7ZSM-5 Molecular Sieve Cake Forming Zone

[0051] 8.23 Liquid Receiver

[0052] 9, 12, 20, 24 containers

[0053] 14, 26 Washing Area

[0054] 19 Microsphere filter cake formation zone

[0055] 11, 22 Ion exchange regions

[0056] 27. Recovered filtrate Detailed Implementation

[0057] 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.

[0058] According to the method provided by this invention, it can be done by Figure 1 , Figure 2 The process shown illustrates the implementation of this invention.

[0059] I. Formation of Y-type molecular sieve filter cake

[0060] Y-type molecular sieve, humic acid, and water are mixed at 10-100℃, preferably 50-90℃, to form a slurry. The resulting slurry is continuously loaded from mixing tank 1 through pipeline 2 onto filter cloth 3 of a horizontal vacuum belt filter. The filter cloth moves continuously into the Y-type molecular sieve filter cake forming zone 4. A liquid receiver 8 is located below the filter cloth 3. The liquid receiver 8 is evacuated, and under vacuum, the liquid in the slurry on the filter cloth 3 passes through the filter cloth 3 and enters the liquid receiver 8. Simultaneously, a filter cake is formed on the Y-type molecular sieve slurry on the filter cloth 3. The loading rate of the Y-type molecular sieve slurry should ensure that the thickness of the formed Y-type molecular sieve filter cake is 0.5-1.5 cm, preferably 0.8-1.5 cm. The vacuum level in the vacuum chamber 8 ensures that the filter cake surface is free of cracks. The vacuum level in the vacuum chamber 8 is generally 0.02-0.08 MPa, preferably 0.05-0.08 MPa.

[0061] II. Formation of ZSM-5 Molecular Sieve Filter Cake

[0062] ZSM-5 molecular sieve slurry at 50-100℃ is continuously loaded from the mixing tank 5 through pipeline 6 onto the Y-type molecular sieve filter cake layer of the horizontal vacuum belt filter, and moves with the filter cloth into the ZSM-5 molecular sieve filter cake forming zone 7. The phosphorus-containing wastewater can be supplied by the microsphere exchange process liquid receiver 23 described below, which reduces water consumption and recovers phosphorus from the filtrate of the catalyst microsphere ion exchange process, thus reducing wastewater discharge. Simultaneously, a filter cake is formed on the filter cloth 3 from the ZSM-5 molecular sieve slurry. The loading rate of the ZSM-5 molecular sieve slurry should ensure that the thickness of the formed ZSM-5 molecular sieve filter cake is 0.5-1.5 cm, preferably 0.8-1.5 cm.

[0063] III. Composite Molecular Sieve Ion Exchange

[0064] As the filter cloth 3 moves, the filter cakes formed in the Y-type molecular sieve filter cake forming zone 4 and the ZSM-5 filter cake forming zone 7 enter the ion exchange zone 11. A phosphorus-containing exchange solution at a temperature of 20-100℃, preferably 30-90℃, is added through the container 9 and pipeline 10. Under vacuum, the phosphorus-containing exchange solution undergoes ion exchange as it passes through the filter cake.

[0065] IV. Composite Molecular Sieve Washing

[0066] The washing method is well known to those skilled in the art. The filter cake obtained in the ion exchange zone 11 enters the water washing zone 14, where deionized water is added from the container 12 via pipeline 13. The weight ratio of deionized water to the composite molecular sieve is generally 1-15, preferably 2-10, and the temperature of the deionized water is 20-100℃, preferably 30-90℃. Under vacuum, the liquid permeates through the filter cake, washing away residual ions, especially anions, from the filter cake.

[0067] V. Microsphere Molding and Curing of Additives

[0068] The washed composite molecular sieve filter cake enters the pulping tank 15, where inorganic oxides, clay, binder and water are added and mixed into a pulp. The pulp is then spray-molded, calcined and cured to obtain additive microspheres.

[0069] VI. Formation of Microsphere Filter Cake

[0070] The curing agent microspheres are fed into the slurry tank 16, where water is added and the mixture is slurried. The microsphere slurry is continuously loaded from the slurry tank 16 onto the filter cloth 18 of the horizontal vacuum belt filter via pipeline 17. The filter cloth moves continuously into the microsphere filter cake forming zone 19. A liquid receiver 23 is located below the filter cloth 18. The liquid receiver 23 is evacuated, and under vacuum, the liquid in the slurry on the filter cloth 18 passes through the filter cloth 18 and enters the liquid receiver 23. Simultaneously, a filter cake forms on the filter cloth 18 from the microsphere slurry. The loading rate of the microsphere slurry should ensure that the thickness of the formed microsphere filter cake is 0.5-2.0 cm, preferably 0.8-1.5 cm. The vacuum degree in the vacuum chamber 23 is generally 0.02-0.08 MPa, preferably 0.03-0.08 MPa.

[0071] VII. Additive Microsphere Phosphorus Exchange

[0072] As the filter cloth 18 moves, the filter cake formed in the microsphere filter cake forming zone 19 enters the ion exchange zone 22, where a phosphorus-containing exchange solution at a temperature of 20-100℃, preferably 30-90℃, is added through the container 20 and pipeline 21. Under vacuum, the phosphorus-containing exchange solution undergoes ion exchange as it passes through the filter cake.

[0073] 8. Washing of Additive Microspheres

[0074] The washing method is well known to those skilled in the art. The filter cake obtained in the ion exchange zone 22 enters the water washing zone 26. Deionized water is added to the microsphere filter cake obtained in the ion exchange zone 22 through the container 24 and pipeline 25. The weight ratio of deionized water to microspheres is generally 1-15, preferably 2-10, and the temperature of the deionized water is 20-100℃, preferably 30-90℃. Under vacuum, the liquid permeates through the filter cake, washing away residual ions in the filter cake.

[0075] The following example uses a cloth funnel filter to illustrate the method provided by this invention. Since the cloth funnel filter also involves stages such as cake formation, ion exchange, and washing, but these steps are performed separately, it is equivalent to the continuous process performed on a belt filter.

[0076] Raw material source:

[0077] 1) USY molecular sieve: produced by Lanzhou Petrochemical Company, with a Na2O content of 0.9% and a cell constant of 24.36 Å;

[0078] REY molecular sieve: produced by Lanzhou Petrochemical Company, with Na2O content of 1.1%, RE2O3 content of 14.8%, and cell constant of 24.66 Å;

[0079] HY molecular sieve: produced by Lanzhou Petrochemical Company, with a Na2O content of 1.5% and a cell constant of 24.39 Å;

[0080] NH4Y molecular sieve: produced by Lanzhou Petrochemical Company, with a Na2O content of 1.2% and a cell constant of 24.41 Å;

[0081] REHY molecular sieve: produced by Lanzhou Petrochemical Company, with Na2O content of 1.3%, RE2O3 content of 1.5%, and cell constant of 24.45 angstroms;

[0082] REUSY molecular sieve: produced by Lanzhou Petrochemical Company, with a Na2O content of 0.8%, a RE2O3 content of 0.9%, and a cell constant of 24.39 Å;

[0083] Fe-ZSM-5 molecular sieve: produced by Lanzhou Petrochemical Company, with a molar ratio (SiO2 / Al2O3) of 40;

[0084] Zn-ZSM-5 molecular sieve: produced by Lanzhou Petrochemical Company, with a molar ratio (SiO2 / Al2O3) of 300;

[0085] La-ZSM-5 molecular sieve: produced by Lanzhou Petrochemical Company, with a molar ratio (SiO2 / Al2O3) of 100;

[0086] Kaolin, halloysite, montmorillonite, silica sol, boehmite, and aluminosilicate all come from Lanzhou Petrochemical Company.

[0087] 2) Fulvic acid, brown humic acid, black humic acid, phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, diammonium dihydrogen phosphate, yttrium oxide, magnesium oxide, and silica: analytical grade, all are chemical reagents.

[0088] Specific analysis methods:

[0089] Phosphorus content in filtrate: Detected using an ICP (Inductively Coupled Plasma Emission Spectrometer).

[0090] Comparative Example 1

[0091] Samples were prepared according to patent CN101474573B.

[0092] a. Preparation of aluminum phosphate solution: Dissolve 0.65 kg (dry basis) boehmite and 2.52 kg 85% phosphoric acid in deionized water, mix and prepare aluminum phosphate gel with a solid content of 30 wt%. Stir and gel at 20℃-60℃ for 1-5 hours to obtain aluminum phosphate solution.

[0093] b. Preparation of ZSM-5 molecular sieve modified with multi-organic acids: Weigh 4 kg of ZSM-5 molecular sieve, add water to prepare a slurry with a solid content of 10%, add 3 kg of oxalic acid while stirring, stir and react for 1-5 hours at 20-90℃, filter, and wash the filter cake with deionized water until the filtrate is neutral.

[0094] c. Rare earth conversion: The multi-acid modified ZSM-5 molecular sieve filter cake prepared in step b is mixed with water and pulped to form a molecular sieve slurry with a solid content of 20% by weight. 0.3 kg of YCl3 solution (calculated as Y2O3) is added and stirred for 30-120 minutes. Ammonia water is added to adjust the pH to 11 to precipitate the rare earth molecular sieve in the solution. The mixture is then pulped.

[0095] d. Mixing and pulping: Add the phosphorus aluminum colloid prepared in step a, the molecular sieve modified by the multi-element organic acid in step b and rare earth-modified in step c, 2.5 kg of kaolin, and 1.16 kg of aluminum sol into a mixing and pulping tank, mix and pulp for 1-2 hours, add hydrochloric acid while stirring to adjust the pH value to 3.0, and continue pulping for 30-60 minutes.

[0096] e. Spray drying and shaping;

[0097] f. Washing and drying: Wash with deionized water until the pH of the washing water is between 6 and 7, dry at 80-120℃, and collect microsphere filtrate A and auxiliary product D1, wherein the phosphorus content of microsphere filtrate A is 123 mg / L.

[0098] Comparative Example 2

[0099] Samples were prepared according to patent CN102794194B.

[0100] The preparation of catalytic cracking additives includes the following steps:

[0101] (1) Exchange washing of NaZSM-5 molecular sieve: Weigh 8.7 kg of acetic acid, add an appropriate amount of cold water and stir to dissolve it, then add 18.9 kg of nitric acid with a concentration of 20% by weight, and then continue to add cold water to dilute the solution to 1000 L to prepare a low-concentration mixed acid solution. Control the solution temperature: 1±0.5℃. Add 125 kg of dry NaZSM-5 molecular sieve powder (in the molecular sieve exchange solution, the weight ratio of H2O to dry molecular sieve powder is 8:1) while stirring, and then stir and react at 1±0.5℃ for 2 hours. Then filter the slurry, and rinse the filter cake with 5 times the weight of NaZSM-5 molecular sieve powder with deionized water.

[0102] (2) The product from step (1) was flash-dried and calcined at 550°C for 3 hours;

[0103] (3) Prepare molecular sieve slurry by pulping the product of step (2) according to the ratio of molecular sieve dry basis: water = 1:3;

[0104] (4) Add kaolin, aluminum sol and yttrium oxide to the molecular sieve slurry obtained in step (3) in the ratio of molecular sieve: kaolin: aluminum sol (calculated as alumina): yttrium oxide = 50:27:20:3 to prepare an additive mixed slurry;

[0105] (5) Prepare additive microspheres by spray drying the slurry obtained in step (4) according to the conventional spray drying molding method for preparing propylene additives for catalytic cracking;

[0106] (6) Washing of additives: Weigh 1740 g of acetic acid, add an appropriate amount of cold water and stir to dissolve it, then add 3780 g of nitric acid with a concentration of 20% by weight, and then continue to add cold water to dilute the solution to 1000 L to prepare a low-concentration mixed acid solution. Control the solution temperature: 1±0.5℃. Add 167 kg of dry basis of catalytic cracking propylene additive while stirring (in the additive washing solution, the weight ratio of H2O to dry basis of catalytic cracking propylene additive is 6:1). Then stir and react at 1±0.5℃ for 2 hours. Then filter the slurry and rinse the filter cake with 5 times the weight of dry basis of catalytic cracking propylene additive with deionized water.

[0107] (7) Dry the product gas stream from step (6) to obtain the catalytic cracking propylene additive product, denoted as D2.

[0108] Comparative Example 3

[0109] 1) The ZMS-5 molecular sieve obtained in step 2) of Comparative Example 2 was mixed with phosphorus-containing wastewater (microsphere filtrate A of Comparative Example 1) and slurried. The mass of microsphere filtrate A was 5 times that of ZMS-5 molecular sieve to prepare ZMS-5 molecular sieve slurry. The ZMS-5 molecular sieve slurry was heated to 70°C and stirred for 1 hour. It was then poured into a Buchner funnel, and the filter flask was evacuated to 0.07 MPa to form a ZMS-5 molecular sieve filter cake with a thickness of 10 mm on the filter cloth.

[0110] 3) When there is no liquid on the surface of the filter cake, immediately add an ammonium phosphate solution at 90°C, ensuring the addition speed does not cause cracks to form on the filter cake surface. The amount of ammonium phosphate should be such that the weight ratio of P to ZMS-5 molecular sieve is 0.04. When there is still no liquid on the filter cake surface, immediately add deionized water at 80°C to wash the filter cake, with a weight ratio of deionized water to ZMS-5 molecular sieve of 5. Then remove the molecular sieve filter cake and collect the filtrate B.

[0111] 4) Add kaolin, aluminum sol and yttrium oxide to the molecular sieve slurry obtained in step (3) in the ratio of molecular sieve: kaolin: aluminum sol (calculated as alumina): yttrium oxide = 50:27:20:3 to prepare an additive mixed slurry;

[0112] 5) Prepare additive microspheres by spray drying the slurry obtained in step (4) according to the conventional spray drying molding method for additive preparation, and then calcinate and solidify them.

[0113] 6) Washing the additives: Mix the cured additive microspheres from step 5) with water to make a slurry with an additive microsphere content of 110 g / L. Heat the slurry to 60°C and pour it into a Buchner funnel. At the same time, evacuate the filter flask to 0.06 MPa to form a filter cake with a thickness of 10 mm on the filter cloth.

[0114] 7) When there is no liquid on the surface of the filter cake in step 6), immediately add an ammonium phosphate solution at 90°C, with the amount of ammonium phosphate used so that the weight ratio of P to microspheres is 0.03. While there is still no liquid on the surface of the filter cake, immediately add deionized water at 90°C to wash the filter cake, with the weight ratio of deionized water to microspheres being 5. Then remove the filter cake and collect the filtrate C, dry it to obtain the auxiliary agent sample D3, and the phosphorus content of the filtrate B is 158 mg / L.

[0115] Example 1

[0116] 1) Mix USY molecular sieve with fulvic acid and water to make a molecular sieve slurry with a molecular sieve content of 180 g / L. The amount of fulvic acid added is 0.03:1 by dry weight of fulvic acid to USY molecular sieve. Heat the obtained molecular sieve slurry to 80°C and pour it into a Buchner funnel. At the same time, evacuate the filter flask to 0.07 MPa to form a filter cake with a thickness of 10 mm on the filter cloth.

[0117] 2) The ZSM-5 molecular sieve obtained in step 2) of Comparative Example 2 is mixed with phosphorus-containing wastewater (microsphere filtrate A of Comparative Example 1) and slurried. The mass of microsphere filtrate A is 5 times that of the molecular sieve to prepare ZSM-5 molecular sieve slurry. The ZSM-5 molecular sieve slurry is heated to 70°C and stirred for 1 hour. It is then poured into the Buchner funnel onto the USY filter cake from step 1). At the same time, the filter flask is evacuated to 0.07 MPa to form a ZSM-5 molecular sieve filter cake with a thickness of 10 mm on the filter cloth.

[0118] 3) When there is no liquid on the surface of the filter cake, immediately add ammonium phosphate solution at 90℃, ensuring the addition speed prevents cracking on the filter cake surface. The amount of ammonium phosphate used should be such that the weight ratio of P to ZSM-5 molecular sieve is 0.04. While the filter cake surface is still dry, immediately add deionized water at 80℃ to wash the filter cake, with a deionized water to composite molecular sieve weight ratio of 5. Then remove the composite molecular sieve filter cake and collect the filtrate D, where the dry basis mass ratio of Y-type molecular sieve to ZSM-5 molecular sieve is 6:94.

[0119] 4) Add kaolin, aluminum sol and yttrium oxide to the molecular sieve slurry obtained in step (3) in the ratio of molecular sieve: kaolin: aluminum sol (calculated as alumina): yttrium oxide = 50:27:20:3 to prepare an additive mixed slurry;

[0120] 5) Prepare additive microspheres by spray drying the slurry obtained in step (4) according to the conventional spray drying molding method for additive preparation, and then calcinate and solidify them.

[0121] 6) Washing the additives: Mix the cured additive microspheres from step 5) with water to make a slurry with an additive microsphere content of 110 g / L. Heat the slurry to 60°C and pour it into a Buchner funnel. At the same time, evacuate the filter flask to 0.06 MPa to form a filter cake with a thickness of 10 mm on the filter cloth.

[0122] 7) When there is no liquid on the surface of the filter cake in step 6), immediately add an ammonium phosphate solution at 90°C, with the amount of ammonium phosphate used so that the weight ratio of P to microspheres is 0.03. While there is still no liquid on the surface of the filter cake, immediately add deionized water at 90°C to wash the filter cake, with the weight ratio of deionized water to microspheres being 5. Then remove the filter cake and collect the filtrate E. Dry the filter cake to obtain the auxiliary agent sample S1, and the phosphorus content of the filtrate D is 0.8 mg / L.

[0123] Example 2

[0124] The operation steps are the same as in Example 1, except that:

[0125] Step 1) The REY molecular sieve slurry content is 300 g / L, the ratio of added humic acid to the dry weight of REY molecular sieve is 0.001:1, the slurry temperature is 15℃, the vacuum degree of the filter bottle is 0.08 MPa, and the filter cake thickness is 5 mm.

[0126] Step 2) Mix Fe-ZSM-5 molecular sieve with phosphorus-containing wastewater (filtrate E) and slurry. The amount of filtrate E is twice that of molecular sieve. The slurry temperature is 50℃. Stir for 2 hours. The vacuum degree of the filter bottle is 0.08 MPa. The thickness of the filter cake is 15 mm.

[0127] Step 3) The amount of diammonium hydrogen phosphate used is such that the weight ratio of P to ZSM-5 molecular sieve is 0.005. The temperature of deionized water is 100℃, and the weight ratio of deionized water to molecular sieve is 1. Remove the molecular sieve filter cake and collect the filtrate F.

[0128] Step 4) Molecular sieve: halloysite: silica sol (as silicon dioxide): magnesium oxide = 35:54:10:1.

[0129] Step 5) Spray drying and curing.

[0130] Step 6) The microsphere content is 300 g / L, the slurry temperature is 80℃, the vacuum degree of the filter bottle is 0.02 MPa, and the filter cake thickness is 5 mm.

[0131] Step 7) The weight ratio of ammonium dihydrogen phosphate to the auxiliary agent is 0.10, the temperature of deionized water is 20℃, and the weight ratio of deionized water to auxiliary agent microspheres is 10. Then, the filter cake is removed and filtrate I is collected to obtain auxiliary agent sample S2. The phosphorus content of filtrate F is 0.6 mg / L.

[0132] Example 3

[0133] The operation steps are the same as in Example 1, except that:

[0134] Step 1) The molecular sieve slurry with a dry weight ratio of REUSY to HY of 1:1 has a content of 100 g / L, the amount of black humic acid added is 0.05:1 with the dry weight ratio of molecular sieve, the slurry temperature is 100℃, the vacuum degree of the filter bottle is 0.02 MPa, and the filter cake thickness is 15 mm.

[0135] Step 2) Mix Zn-ZSM-5 molecular sieve with phosphorus-containing wastewater (filtrate I) and slurry. The amount of filtrate I is 10 times that of molecular sieve. The slurry temperature is 100℃. Stir for 0.5h. The vacuum degree of the filter bottle is 0.02 MPa. The thickness of the filter cake is 5 mm.

[0136] Step 3) The temperature is 20℃, and the weight ratio of diammonium hydrogen phosphate to molecular sieve is 0.15. The temperature of deionized water is 20℃, and the weight ratio of deionized water to molecular sieve is 3. Remove the molecular sieve filter cake and collect the filtrate J.

[0137] Step 4) Molecular sieve: Montmorillonite: Boehmite (calculated as alumina): Silica = 40:43:15:2.

[0138] Step 5) Spray drying and curing.

[0139] Step 6) The content of the auxiliary microspheres is 100 g / L, the slurry temperature is 20℃, the vacuum degree of the filter bottle is 0.08 MPa, and the filter cake thickness is 20 mm.

[0140] Step 7) The weight ratio of diammonium hydrogen phosphate to the auxiliary agent is 0.005, the temperature of deionized water is 100℃, and the weight ratio of deionized water to auxiliary agent microspheres is 7. Then, the filter cake is removed and the filtrate K is collected to obtain auxiliary agent sample S3, and the phosphorus content of filtrate J is 0.4 mg / L.

[0141] Example 4

[0142] The operation steps are the same as in Example 1, except that:

[0143] Step 1) The dry basis mass ratio of NH4Y to REHY is 1:3, the molecular sieve slurry content is 180 g / L, the addition amount of black humic acid and yellow humic acid is 0.03:1 with the dry basis weight of molecular sieve, the slurry temperature is 75℃, the vacuum degree of the filter bottle is 0.04 MPa, and the filter cake thickness is 8 mm.

[0144] Step 2) The rare earth ZSM-5 molecular sieve obtained in step c of Comparative Example 1 was mixed with phosphorus-containing wastewater (filtrate K) and slurried. The amount of filtrate K was 4 times that of the molecular sieve. The slurry temperature was 70℃. The mixture was stirred for 1.5h. The vacuum degree of the filter bottle was 0.04 MPa. The thickness of the filter cake was 13 mm.

[0145] Step 3) The weight ratio of phosphoric acid to molecular sieve is 0.01, the temperature of deionized water is 40℃, and the weight ratio of deionized water to molecular sieve is 8. Remove the molecular sieve filter cake and collect the filtrate L.

[0146] Step 4) Molecular sieve: kaolin: alumina sol (calculated as alumina): yttrium oxide = 45:34.5:20:0.5.

[0147] Step 5) Spray drying and curing.

[0148] Step 6) The content of the auxiliary microspheres is 170 g / L, the slurry temperature is 60℃, the vacuum degree of the filter bottle is 0.04 MPa, and the filter cake thickness is 18 mm.

[0149] Step 7) The weight ratio of phosphoric acid to the auxiliary agent is 0.02. The temperature of the deionized water is 60℃, and the weight ratio of deionized water to the auxiliary agent is 9. After the filter cake is dried at 200℃, it is calcined at 500℃ for 1 hour. Then the filter cake is removed and the filtrate M is collected to obtain the auxiliary agent sample S4. The phosphorus content of the filtrate L is 0.5 mg / L.

[0150] Example 5

[0151] Using industrial-grade LDO-75 catalyst as the main catalyst, it was mixed with the additives prepared in Examples 1-4 and Comparative Examples 1-3 at a weight ratio of 95:5 to obtain a homogeneous mixed catalyst. The resulting mixed catalyst was aged at 800°C for 10 hours using 100% steam. The catalytic performance of the mixed catalyst was evaluated using 3 million tons / year catalytic feedstock from Lanzhou Petrochemical (properties shown in Table 1) on a fixed fluidized bed reactor. The blank sample represents the evaluation results of the main catalyst without additives. The evaluation conditions were: reaction temperature 500°C, regeneration temperature 700°C, and catalyst-to-oil ratio 4. The evaluation results are shown in Table 2.

[0152] Table 1 Properties of Catalytic Feedstock

[0153]

[0154] Table 2. Evaluation results of adjuvants, %

[0155]

[0156] The results of Examples S1 to S4 show that the phosphorus content of the filtrate obtained by the method of the present invention is less than 1 mg / L, which meets the national secondary discharge standard. Compared with Comparative Example 1, the operation process of the present invention is simple and the wastewater can be directly discharged on existing auxiliary agent preparation devices. Compared with Comparative Example 2, the method of the present invention is operable in actual production. Comparative Example 2 requires exchange at a temperature of 0-5℃, which is harsh and difficult to implement in industrial production, and cannot meet the needs of actual production. The evaluation data shows that the auxiliary agent prepared by the method of the present invention can improve the propylene yield and propylene selectivity of the catalytic cracking catalyst. Moreover, the auxiliary agent filtrate prepared by the method provided by the present invention has a low phosphorus content, requires no treatment, can meet the requirements for direct discharge, and has good operability, showing great promise for industrial application.

[0157] 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 method for preparing a catalytic cracking propylene additive, characterized in that, Includes the following steps: 1) Y-type molecular sieve, humic acid and water are slurried to obtain Y-type molecular sieve slurry, and the Y-type molecular sieve slurry is filtered to form Y-type molecular sieve filter cake layer. The dry weight ratio of humic acid to Y-type molecular sieve is 0.001-0.

05. 2) ZSM-5 molecular sieve is slurried with phosphorus-containing wastewater to obtain ZSM-5 molecular sieve slurry. The ZSM-5 molecular sieve slurry is filtered through a Y-type molecular sieve filter cake layer to form a ZY composite filter cake layer. The ZY composite filter cake layer is ion exchanged with a first phosphorus-containing exchange solution and then washed with water to obtain a ZY composite molecular sieve filter cake. The amount of the first phosphorus-containing exchange solution used is 0.005-0.15 by weight of the dry basis of ZSM-5 molecular sieve (calculated as P). 3) The ZY composite molecular sieve filter cake, inorganic oxide, clay, binder and water are mixed and pulped, spray dried and shaped, and calcined to obtain auxiliary microspheres. The auxiliary microspheres are mixed with water and pulped, then filtered to form microsphere filter cake. The microsphere filter cake is ion exchanged with a second phosphorus-containing exchange solution, then washed with water and dried to obtain catalytic cracking propylene auxiliary agent. The amount of the second phosphorus-containing exchange solution and the weight ratio of the dry basis of the microspheres is 0.005-0.10 (calculated as P).

2. The method for preparing the catalytic cracking propylene additive according to claim 1, characterized in that, The Y-type molecules are selected from one or more of USY, REY, HY, REHY, NH4Y, and REUSY.

3. The method for preparing the catalytic cracking propylene additive according to claim 1, characterized in that, The humic acid is selected from one or more of fulvic acid, brown humic acid, and black humic acid.

4. The method for preparing the catalytic cracking propylene additive according to claim 1, characterized in that, The ZSM-5 molecular sieve is a ZSM-5 molecular sieve modified with metal ions.

5. The method for preparing the catalytic cracking propylene additive according to claim 4, characterized in that, The metal ions are rare earth ions.

6. The method for preparing the catalytic cracking propylene additive according to claim 1, characterized in that, The mass ratio of the phosphorus-containing wastewater to the ZSM-5 molecular sieve is 2-10.

7. The method for preparing the catalytic cracking propylene additive according to claim 6, characterized in that, The mass ratio of the phosphorus-containing wastewater to the ZSM-5 molecular sieve is 3-6.

8. The method for preparing the catalytic cracking propylene additive according to claim 1, characterized in that, The first phosphorus-containing exchange solution and the second phosphorus-containing exchange solution are one or more of ammonium phosphate solution, diammonium hydrogen phosphate solution, diammonium dihydrogen phosphate solution and phosphoric acid.

9. The method for preparing the catalytic cracking propylene additive according to claim 1, characterized in that, The inorganic oxide is one or more of rare earth oxide, magnesium oxide and silicon oxide; the clay is one or more of kaolin, halloysite and montmorillonite; the binder is one or more of alumina sol, silica sol and boehmite.

10. The method for preparing the catalytic cracking propylene additive according to claim 1, characterized in that, Steps 1) and 2) are performed on a first horizontal belt filter, which includes a Y-type molecular sieve cake forming zone, a ZMS-5 molecular sieve cake forming zone, a phosphorus exchange zone, and a water washing zone connected in series; Step 3) is performed on a second horizontal belt filter, which includes a microsphere cake forming zone, a phosphorus exchange zone, and a water washing zone connected in series.

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