Phosphorus and rare earth-containing y-type molecular sieve and method for preparing the same

Abstract

The application discloses a Y-type molecular sieve containing phosphorus and rare earth and a preparation method thereof. The preparation method comprises the following steps: forming a NaY molecular sieve filter cake layer from a slurry of NaY molecular sieve; mixing the NaY molecular sieve with a solution containing phosphorus filtrate and a rare earth salt to form a RE-NaY molecular sieve filter cake layer on the NaY molecular sieve filter cake layer, thereby obtaining a composite filter cake; performing ion exchange on the composite filter cake obtained in step 2 with a phosphate solution, washing with water, and calcining, thereby obtaining the Y-type molecular sieve containing phosphorus and rare earth; and the ion exchange and water washing are performed at least once. The preparation method of the Y-type molecular sieve containing phosphorus and rare earth can solve the problems of low rare earth utilization rate and serious phosphorus pollution in the production process of the Y-type molecular sieve containing phosphorus and rare earth, realizes efficient utilization of phosphorus and rare earth in the preparation process of the Y-type molecular sieve containing phosphorus and rare earth, and ensures continuous production of the molecular sieve.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve materials and their preparation, specifically to a phosphorus- and rare earth-containing Y-type molecular sieve and its preparation method. Background Technology

[0002] With the increasing severity and deterioration of crude oil, efficient processing of heavy oil and blending of residue oil have become urgent needs for refineries to improve processing capacity and obtain higher profits. Catalytic cracking is the most important process for heavy oil processing. Due to its significant advantages such as high heavy oil conversion efficiency, good product quality, non-hydrogenation, and low operating pressure, it occupies a pivotal position in refinery heavy oil processing and is a major source of refinery profits.

[0003] Because heavy oil and residual oil contain large molecular compounds such as gums and asphaltenes that easily produce coke, and also contain heavy metals such as nickel and vanadium, nickel and vanadium content in catalytic cracking equilibrium catalysts is commonly found at 10,000 μg / g, and severe contamination as high as 15,000 μg / g is not uncommon. Vanadium severely damages the structure of the active component molecular sieve in the catalyst under the high-temperature hydrothermal environment of catalytic cracking, resulting in reduced catalyst activity and poorer product distribution in catalytic cracking. Therefore, it is necessary to develop molecular sieves with excellent activity, hydrothermal stability, and resistance to heavy metal contamination to meet the stringent requirements for catalyst performance in heavy oil and residual oil cracking.

[0004] To improve the activity and stability of molecular sieves, existing technologies generally employ rare earth elements to modify them. For example, Chinese patent CN1169717C discloses a method and product for modifying Y zeolite with rare earth ions. This method uses NaY molecular sieves as raw materials, first subjecting them to ammonium exchange, then hydrothermal treatment, and finally using H-containing... + NH 4+ and RE 3+ After solution treatment, the modified molecular sieve product is obtained through washing, drying, and calcination. Chinese patent CN1026225C discloses a method for preparing rare earth Y molecular sieves, which involves ion exchange between NaY molecular sieves and rare earth ions in an aqueous solution, followed by filtration, and calcination of the filter cake in flowing steam. Chinese patent CN1069553C discloses a method for preparing rare earth Y-type molecular sieves, which involves ion exchange between NaY molecular sieves and rare earth ions, followed by filtration, and then calcination of the filter cake. 1-40% of the calcined product is recycled back to the next batch of rare earth exchange slurry to continue the above operations, while the remainder is used as REY molecular sieve product for catalyst preparation. This process is repeated continuously to obtain rare earth Y-type molecular sieves. Chinese patent CN103058217A discloses a method for preparing rare earth-containing Y molecular sieves, which uses NaY molecular sieves as raw material, first undergoing ammonium exchange, then hydrothermal treatment, and finally using H-containing... + NH 4+and RE 3+ After treatment with a mixed solution of organic solvent, the mother liquor is separated, and the filter cake is calcined to obtain the modified molecular sieve product. Chinese patent CN1159101C discloses a method for preparing rare-earth-containing ultrastable Y zeolite. This method involves mixing ultrastable Y zeolite with a sodium oxide content of 3-5% by weight with a rare-earth compound solution to form a slurry. The resulting slurry is then ground under a shear stress of at least 10 kg / cm² for at least 1 minute to obtain the modified molecular sieve product. The zeolite prepared by this method exhibits high hydrothermal stability, activity stability, and resistance to sodium and heavy metal contamination.

[0005] To further improve the catalytic performance of ultrastable rare earth Y-type molecular sieves, relevant literature has proposed methods for phosphorus modification.

[0006] Chinese patent CN1111136C discloses a method for preparing a phosphorus- and rare earth-containing Y-type molecular sieve. The method involves first exchanging NaY molecular sieve with ammonium and rare earth ions, followed by calcination, then reacting it with a phosphorus compound to combine it with 1-10% by weight of P2O5, followed by further calcination. Chinese patent CN1209288C discloses a method for preparing a phosphorus- and rare earth-containing octahedral zeolite. This method involves first exchanging the octahedral zeolite with an ammonium and phosphorus compound, then introducing a rare earth solution into the exchange slurry for further reaction, followed by filtration, washing, and calcination. Catalysts containing this zeolite exhibit good activity and stability, high gasoline yield, low coke yield, strong heavy oil cracking ability, and resistance to heavy metal pollution.

[0007] Chinese patent CN1353086A discloses a method for preparing a phosphorus- and rare earth-containing Y-type molecular sieve. The resulting Y-type molecular sieve can significantly reduce the olefin content of FCC gasoline while maintaining good coke selectivity. The method includes first exchanging the NaY molecular sieve with a mixture of ammonium ions and rare earth ions and then hydrothermally calcining it, then reacting it with a phosphorus compound to bind 0.2-10% by weight (calculated as P2O5) of phosphorus, and then hydrothermally calcining it again.

[0008] Chinese patent CN1330981A discloses a phosphorus-containing Y-type zeolite and its preparation method. This molecular sieve is obtained by co-leaching rare earth-containing Y-type zeolite with a solution containing silicon and phosphorus, drying it, and then hydrothermally calcining it at 550-850℃.

[0009] Chinese patent CN1317547A discloses a method for preparing phosphorus and rare earth composite modified ultrastable Y zeolite. The method involves mixing and exchanging rare earth elements with ammonium salts in NaY zeolite, followed by hydrothermal calcination, and then reacting with phosphorus compounds for a second calcination. The weight ratio of RE₂O₃ / Y zeolite is 0.02-0.18, the weight ratio of ammonium salt / Y zeolite is 0.1-1.0, and the weight ratio of P / Y zeolite is 0.003-0.05. The calcination temperature is 250-750℃, the moisture content is 5-100%, and the time is 0.2-3.5 hours. The rare earth content in the resulting zeolite is 2-12%, and the cell constant is [not specified]. The phosphorus content is 0.2-3% (calculated as P).

[0010] In existing technologies, after rare earth ion and phosphorus exchange in molecular sieves, the mixture is typically filtered, and the filter cake is then calcined. This results in incomplete exchange of rare earth and phosphorus onto the molecular sieve; some rare earth and phosphorus are lost into the filtrate, leading to low rare earth utilization and phosphorus loss. Therefore, improving the rare earth utilization rate and reducing phosphorus-containing wastewater discharge during the Y-type molecular sieve ion exchange process has become a key research focus.

[0011] There are two industrial methods for ion exchange using NaY molecular sieves: The first method involves mixing the Y-type molecular sieve with an aqueous solution containing rare earth ions to form a slurry, followed by ion exchange, filtration, washing, drying, and calcination (or no calcination). A plate and frame filter press is used for filtration. The disadvantages of this method are low efficiency and high water consumption. The second method involves mixing the Y-type molecular sieve with water to form a Y-type molecular sieve slurry. This slurry is directly transferred onto the filter cloth of a belt filter, forming a filter cake of a certain thickness. An aqueous solution of ammonium ions and / or rare earth ions is then added from above the filter cake. Under vacuum in the liquid receiver below the filter cloth, the solution containing ammonium ions and / or rare earth ions continuously passes through the filter cake, resulting in ion exchange. Belt filters are energy-efficient and highly effective, and are widely used in large-scale industrial production.

[0012] US Patent 3943233 discloses a method for continuous ion exchange of fluidizable zeolite particles. The method includes slurrying the zeolite particles with a first liquid, loading the slurry at a substantially constant rate into the feed end of a continuous horizontal belt vacuum filter, continuously moving the filter belt containing the slurry through a cake forming zone, at least one ion exchange zone, and a washing zone, while simultaneously applying vacuum to liquid receivers under each independent filter belt, and unloading the filter cake from the filter belt. The method is characterized by the filter cake leaving the cake forming zone with substantially no surface cracks, but containing liquid within the voids of the fluidizable zeolite particles. During the ion exchange process, the filter cake, in the ion exchange zone, contacts an ion exchange liquid under filtration conditions, leaves the ion exchange zone as a smooth, substantially crack-free filter cake containing liquid within the voids of the fluidizable zeolite particles, and is rapidly washed under vacuum after ion exchange.

[0013] Chinese patent CN1142024C discloses a method for rare earth ion exchange using a molecular sieve. The method includes slurrying a molecular sieve with water, continuously transferring the resulting slurry onto the filter belt of a horizontal belt vacuum filter, sequentially passing it through a cake forming zone and an ion exchange zone, applying vacuum to the liquid receivers under the filter belts in both the cake forming and ion exchange zones, washing and drying the filter cake, and removing the filter cake from the filter belt. The method is characterized by using a Y-type molecular sieve (cross-linked and calcined), adding acid and / or salt to the slurry (the amount of acid or salt being 0.1-5% by weight of the molecular sieve), ensuring the vacuum level in the liquid receivers of the cake forming zone is such that the filter cake surface is essentially free of cracks, and adding a rare earth ion-containing solution to the upper part of the filter cake in the ion exchange zone, with the concentration of the rare earth ion-containing solution such that the weight ratio of rare earth oxides to the molecular sieve is 0.01-0.5%.

[0014] Chinese patent CN1485136A describes a method for continuously loading a molecular sieve-containing slurry with a pH of 2-7 onto the filter cloth of a horizontal belt filter. The filter cloth loaded with the molecular sieve slurry is then sequentially passed through a cake forming zone, an ion exchange zone, and a washing zone. Afterward, it is blotted dry, unloaded, and dried to obtain the exchanged molecular sieve filter cake. In the ion exchange zone, an aqueous solution of rare earth compounds at a temperature of 10-100℃ is added from the top of the filter cake. The amount of rare earth compound aqueous solution used is such that the weight ratio of rare earth oxides to molecular sieves is 0.01-0.2.

[0015] Chinese patent CN108097288A provides a method for preparing rare earth Y-type molecular sieves. This method includes first mixing NaY molecular sieves, rare earth chloride solution, and deionized water, followed by ion exchange. Oxalic acid solution is added to the exchange solution to completely precipitate unexchanged rare earth. Rare earth chloride and deionized water are then added to the filtered filter cake for further ion exchange. The resulting filter cake and recycled filtrate are then filtered. The filter cake is calcined in a muffle furnace to obtain the product REY. The recycled filtrate completely or partially replaces the aforementioned rare earth chloride solution and enters the ion exchange process for the next batch of NaY molecular sieves. This method can recycle rare earth, achieving almost 100% utilization without increasing equipment, reducing production costs, and efficiently utilizing non-renewable rare earth resources.

[0016] Current technologies mainly focus on the efficient utilization of rare earth ions and phosphorus removal methods for phosphorus-containing wastewater, but there are no reports on improving the phosphorus utilization rate in the molecular sieve exchange process. 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 the molecular sieve preparation process and seriously affects the production capacity of molecular sieves.

[0017] Therefore, how to effectively improve the utilization rate of phosphorus and rare earth elements in the ion exchange process of Y-type molecular sieve belt filters is an important measure for molecular sieve manufacturers to reduce costs and increase efficiency, and it is also one of the key research topics for molecular sieve manufacturers. Summary of the Invention

[0018] The purpose of this invention is to develop a phosphorus- and rare earth-containing Y-type molecular sieve and its preparation method, which can solve the problems of low rare earth utilization and serious phosphorus pollution in the production process of phosphorus- and rare earth-containing Y-type molecular sieves, realize the efficient utilization of phosphorus and rare earth in the preparation process of phosphorus- and rare earth-containing Y-type molecular sieves, and ensure continuous production of molecular sieves.

[0019] To achieve this objective, the present invention provides a method for preparing a phosphorus- and rare earth-containing Y-type molecular sieve, comprising the following steps:

[0020] Step 1: Form a NaY molecular sieve filter cake layer from the NaY molecular sieve slurry;

[0021] Step 2: Mix NaY molecular sieve with phosphorus-containing filtrate and rare earth salt solution to form RE-NaY molecular sieve filter cake layer on the NaY molecular sieve filter cake layer, and obtain composite filter cake;

[0022] Step 3: The phosphate solution is subjected to ion exchange with the composite filter cake obtained in Step 2, followed by water washing and calcination to obtain a Y-type molecular sieve containing phosphorus and rare earth elements.

[0023] The ion exchange and water washing are performed at least once.

[0024] The present invention relates to a method for preparing a phosphorus- and rare earth-containing Y-type molecular sieve, wherein the slurry of the NaY molecular sieve comprises NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid and water.

[0025] The method for preparing phosphorus- and rare earth-containing Y-type molecular sieves of the present invention, wherein the alkali metal hydroxide is potassium hydroxide, the carbonate is potassium carbonate, and the dry weight ratio of potassium hydroxide:potassium carbonate:humic acid:NaY molecular sieve is 0.005-0.012:0.005-0.012:0.001-0.05:1.

[0026] The method for preparing phosphorus- and rare-earth-containing Y-type molecular sieves of the present invention is not particularly limited in terms of the NaY molecular sieve and its preparation method. The NaY molecular sieve can be prepared by existing methods or is commercially available. For example, the NaY molecular sieve synthesis method provided in patent CN103449468B involves mixing water glass, sodium aluminate, and deionized water, and aging at 15-70°C for 0.5-48 hours to obtain a crystallization guiding agent; uniformly mixing the crystallization guiding agent, water glass, acidic aluminum salt, and sodium aluminate solution to obtain a silica-alumina gel; crystallizing the silica-alumina gel at 80-140°C for 0.1-80 hours; and adding peroxide to the crystallized silica-alumina gel to allow the O2 in the peroxide to dissolve. 2- The molar ratio of sodium oxide to Al₂O₃ in the gel is 0.05-20, followed by further crystallization for 5-20 hours. The sodium oxide content in the NaY molecular sieve is, for example, but not limited to, 9-15 wt%.

[0027] The method for preparing phosphorus- and rare earth-containing Y-type molecular sieves of the present invention, wherein the humic acid is at least one of fulvic acid, brown humic acid, and black humic acid.

[0028] The preparation method of the phosphorus- and rare-earth-containing Y-type molecular sieve of the present invention does not particularly limit the preparation process of the NaY molecular sieve slurry. For example, the preparation process can involve mixing NaY molecular sieve, potassium hydroxide, potassium carbonate, humic acid, and water to form a slurry; the content of NaY molecular sieve in the slurry is, for example, but not limited to, 100-300 g / L. The temperature of the slurry can be 10-100℃, preferably 50-90℃.

[0029] In the preparation method of phosphorus- and rare-earth-containing Y-type molecular sieves of the present invention, in step 2, the phosphorus-containing filtrate can be the filtrate recovered in step 2 or step 3, or it can be the phosphorus-containing filtrate collected or prepared by other processes outside the present invention, preferably the filtrate recovered in step 3. In step 2, the mass ratio of the phosphorus-containing filtrate to the NaY molecular sieve is 2:10, preferably 3-6.

[0030] In the preparation method of the phosphorus- and rare earth-containing Y-type molecular sieve of the present invention, in step 2, the rare earth salt, calculated as rare earth oxide, is added in a mass ratio of 0.01-0.10 to the NaY molecular sieve, preferably 0.05-0.10.

[0031] In the preparation method of phosphorus- and rare earth-containing Y-type molecular sieves of the present invention, the temperature and time of pulping in step 2 are not particularly limited by the present invention, and can be, for example, stirred at a temperature of 50-100°C for 0.5-2 hours.

[0032] The present invention discloses a method for preparing phosphorus- and rare earth-containing Y-type molecular sieves, wherein the preparation method is carried out on a belt filter; the belt filter includes at least one cake forming zone, at least one ion exchange zone, and at least one water washing zone.

[0033] In the preparation method of the phosphorus- and rare earth-containing Y-type molecular sieve of the present invention, in step 3, the phosphate solution is added from the top of the composite filter cake and flows through the composite filter cake to perform ion exchange; the weight ratio of the phosphate solution in step 3 to the NaY molecular sieve in step 2 is 0.005-0.05, calculated as phosphorus element.

[0034] The preparation method of the phosphorus- and rare earth-containing Y-type molecular sieve of the present invention includes step 3 as follows: A phosphate solution is subjected to a first ion exchange with the composite filter cake obtained in step 2, followed by a first calcination to obtain a calcined molecular sieve; the calcined molecular sieve is slurried with water to form a filter cake; the phosphate solution is subjected to a second ion exchange with the filter cake, followed by a second calcination to obtain the phosphorus- and rare earth-containing Y-type molecular sieve; the weight ratio of the phosphate solution to the calcined molecular sieve in step 3 is 0.02-0.15, calculated based on phosphorus element.

[0035] The method for preparing phosphorus- and rare earth-containing Y-type molecular sieves of the present invention comprises, in step 2, the filtrate formed during the formation of the RE-NaY molecular sieve filter cake layer, in step 3, the filtrate formed during the first ion exchange, the filtrate formed during the formation of the filter cake from the slurry of the molecular sieve and water, and the filtrate formed during the second ion exchange, at least one of which is used as the phosphorus-containing filtrate of step 2.

[0036] The method for preparing phosphorus- and rare earth-containing Y-type molecular sieves of the present invention uses the same horizontal belt filter in steps 1 and 2. The horizontal belt filter is equipped with a NaY filter cake forming zone and a cross-linked molecular sieve filter cake forming zone connected in series. The RE-NaY cross-linked molecular sieve slurry is added to the NaY filter cake layer in the cross-linked molecular sieve filter cake forming zone to form an RE-NaY cross-linked molecular sieve composite filter cake layer.

[0037] The method for preparing phosphorus- and rare earth-containing Y-type molecular sieves of the present invention involves obtaining the final phosphorus- and rare earth-containing Y-type molecular sieve by drying and calcining the molecular sieve filter cake after water washing in step 3, or by not spray drying and calcining.

[0038] The method for preparing phosphorus- and rare earth-containing Y-type molecular sieves of the present invention, wherein the rare earth salt is one or more of water-soluble rare earth salts, preferably rare earth chloride and rare earth nitrate; the rare earth is selected from at least one of lanthanum, cerium, praseodymium, neodymium, and yttrium.

[0039] The method for preparing phosphorus- and rare earth-containing Y-type molecular sieves of the present invention, wherein the phosphate in the phosphate solution is one or more water-soluble phosphates, preferably at least one of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate.

[0040] The method for preparing phosphorus- and rare earth-containing Y-type molecular sieves of the present invention does not particularly limit the conditions for water washing, but can be, for example, at a temperature of 20-100°C, preferably 60-80°C, with a mass ratio of water to molecular sieve of 1-15, preferably 3-5.

[0041] The method for preparing phosphorus- and rare earth-containing Y-type molecular sieves of the present invention does not particularly limit the drying and calcination conditions. For example, the drying temperature can be room temperature to 200°C, preferably 100-150°C, the calcination temperature can be 500-800°C, preferably 600-700°C, and the calcination time can be 1-3 hours, preferably 2-3 hours.

[0042] The present invention also provides a phosphorus- and rare earth-containing Y-type molecular sieve obtained by the above preparation method.

[0043] The present invention provides a method for preparing phosphorus- and rare earth-containing Y-type molecular sieves. First, a NaY molecular sieve filter cake layer is formed. Then, a phosphorus- and rare earth-exchanged molecular sieve is loaded onto the NaY molecular sieve filter cake layer. Excess phosphorus and rare earth ions in the filtrate are then adsorbed and recovered through the NaY molecular sieve filter cake layer. The method for preparing phosphorus- and rare earth-containing Y-type molecular sieves provided by the present invention can exchange Na+ in the molecular sieve. + Furthermore, the method for preparing phosphorus- and rare earth-containing Y-type molecular sieves provided by this invention is simple and achieves the recovery and utilization of phosphorus and rare earth ions during the molecular sieve exchange process, which can provide technical support for continuous molecular sieve production and energy conservation and consumption reduction in enterprises.

[0044] Furthermore, the present invention adds alkali metal hydroxides and carbonates to the NaY molecular sieve slurry to remove amorphous silica and aluminum on the surface of the NaY molecular sieve without damaging the molecular sieve structure, thereby improving the exchange efficiency of rare earth and Na ions. The humic acid added in this invention is a multi-component organic complex that dissolves in the alkaline system composed of NaY molecular sieve, alkali metal hydroxides, and carbonates to form, for example, sodium humate and potassium humate. Sodium humate and potassium humate can synthesize organic rare earth complexes with rare earth ions through adsorption, exchange, and complexation, thereby limiting the migration of rare earth ions in the filtrate and reducing their loss with the filtrate. Humic acid also has the function of fixing phosphorus, making it less likely for phosphorus to be lost with the filtrate. The method for preparing phosphorus- and rare earth-containing Y-type molecular sieves provided by this invention recovers rare earth and phosphorus lost from the filtrate through the adsorption of the NaY filter cake layer and humic acid, achieving a dual function of phosphorus and rare earth recovery during the NaY molecular sieve exchange process. Attached Figure Description

[0045] Figure 1 This is a flowchart illustrating one embodiment of the preparation method of the present invention.

[0046] Figure 2 This is a flowchart of the two-stage process of one embodiment of the preparation method of the present invention.

[0047] In the attached figures, the following labels are used:

[0048] 1, 5, 15 Pulping Tanks

[0049] Pipelines 2, 6, 10, 13, 16, 20, 24, 26

[0050] 3.17 Filter Cloth

[0051] 4 NaY molecular sieve filter cake formation zone

[0052] 7. Molecular sieve filter cake formation zone

[0053] 8.22 Liquid Receiver

[0054] Containers 9, 12, 19, and 23

[0055] Ion exchange regions 11 and 21

[0056] 14, 25 Washing Area

[0057] 18. Dichroic molecular sieve filter cake formation zone Detailed Implementation

[0058] The following provides a detailed description of the embodiments of the present invention. These embodiments are implemented based on the technical solution of the present invention and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0059] Figure 1 This is a flowchart of a single ion exchange process according to one embodiment of the preparation method of the present invention. Figure 2 This is a flowchart of a secondary ion exchange process according to one embodiment of the preparation method of the present invention. In this embodiment, the preparation method of the phosphorus- and rare-earth-containing Y-type molecular sieve of the present invention may specifically include the following steps:

[0060] I. Formation of NaY Molecular Sieve Filter Cake

[0061] A slurry composed of NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid, and water, prepared at 10-100℃ (preferably 50-90℃), is continuously loaded from a mixing tank 1 onto the filter cloth 3 of a horizontal vacuum belt filter via pipeline 2. The filter cloth moves continuously into the NaY 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 forms on the NaY slurry on the filter cloth 3. The loading rate of the NaY slurry should ensure that the thickness of the formed NaY filter cake is 0.5-1.5 cm, preferably 0.8-1.5 cm. The vacuum level in the liquid receiver 8 prevents cracking on the surface of the filter cake. The vacuum level in the liquid receiver 8 is, for example, but not limited to, 0.02-0.08 MPa, preferably 0.05-0.08 MPa.

[0062] II. Formation of the filter cake

[0063] The 50-100℃ primary molecular sieve slurry is continuously loaded from the mixing tank 5 through pipeline 6 onto the NaY filter cake layer of the horizontal vacuum belt filter, and moves with the filter cloth into the primary molecular sieve filter cake forming zone 7. The phosphorus-containing filtrate can be provided by the liquid receiver 22 of the secondary molecular sieve process (described later) or by the filtrate collected in the liquid collector 8. This reduces water consumption, recovers phosphorus from the secondary process filtrate, reduces wastewater discharge, and improves phosphorus utilization. Simultaneously, the primary molecular sieve slurry forms a filter cake on the filter cloth 3. The loading speed of the primary molecular sieve slurry should ensure that the thickness of the formed primary molecular sieve filter cake is 0.5-1.5 cm, preferably 0.8-1.5 cm.

[0064] III. Phosphate Exchange

[0065] As the filter cloth 3 moves, the filter cake formed in the NaY molecular sieve filter cake forming zone 4 and the cross-linked filter cake forming zone 7 enters the ion exchange zone 11. A phosphate solution at a temperature of 20-100℃, preferably 30-90℃, is added through the container 9 and pipeline 10. Under vacuum, the phosphate solution undergoes ion exchange as it passes through the filter cake.

[0066] IV. Washing

[0067] The washing method can be any method known to those skilled in the art. The filter cake obtained in the ion exchange zone 11 enters the water washing zone 14, and deionized water is added from the container 12 through the pipeline 13. The weight ratio of deionized water to 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.

[0068] V. Formation of the two-stage filter cake

[0069] A mono-calcined molecular sieve slurry at 10-100℃, preferably 50-90℃, is continuously loaded from a mixing tank 15 onto the filter cloth 17 of a horizontal vacuum belt filter via pipeline 16. The filter cloth moves continuously into the di-calcined molecular sieve cake forming zone 18. A liquid receiver 22 is located below the filter cloth 17. The liquid receiver 22 is evacuated, and under vacuum, the liquid in the slurry on the filter cloth 17 passes through the filter cloth 17 and enters the liquid receiver 22. Simultaneously, a filter cake is formed on the mono-calcined molecular sieve slurry on the filter cloth 17. The loading rate of the mono-calcined molecular sieve slurry should ensure that the thickness of the formed mono-calcined molecular sieve filter cake is 0.5-2.0 cm, preferably 0.8-1.5 cm. The vacuum degree in the liquid receiver 22 ensures that the filter cake surface is free of cracks. The vacuum degree in the liquid receiver 22 is, for example, but not limited to, 0.02-0.08 MPa, preferably 0.03-0.08 MPa.

[0070] VI. Phosphate Exchange

[0071] As the filter cloth 17 moves, the filter cake formed in the two-stage filter cake forming zone 18 enters the ion exchange zone 21, where a phosphate solution at a temperature of 20-100°C, preferably 30-90°C, is added through the container 19 and pipeline 20. Under vacuum, the phosphate solution undergoes ion exchange as it passes through the filter cake.

[0072] 7. Two washes

[0073] The washing method can employ methods known to those skilled in the art. Deionized water is added from container 23 through pipeline 24 onto the filter cake obtained in ion exchange zone 21. The weight ratio of deionized water to 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 the filter cake, washing away residual ions.

[0074] The technical solution of the present invention will be further described below through specific embodiments. Unless otherwise specified, all percentages (%) refer to mass percentages. Unless otherwise specified, the rare earth content in the filtrate in the following embodiments and comparative examples refers to the content of rare earth in the filtrate as oxides; the amount of rare earth added refers to the amount as rare earth oxides; in the following embodiments, rare earth oxides and rare earth oxides refer to oxides in the form of RE2O3; the mass of the rare earth-containing filtrate refers to the mass of the rare earth-containing filtrate itself.

[0075] Raw material source:

[0076] 1) NaY molecular sieve: industrial product, produced by Lanzhou Petrochemical Company, with a crystallinity of 94%, a silicon-to-aluminum ratio of 5, and a Na2O content of 14.3%;

[0077] Rare earth chloride solution: Industrial grade, produced by Lanzhou Petrochemical Company, containing 288.7 g / L of rare earth oxides, of which lanthanum oxide content is 46%, cerium dioxide content is 53%, and other rare earth content is 1%.

[0078] 2) Lanthanum-rich rare earth chloride: Industrial product, produced by Lanzhou Petrochemical Company, containing 290g / L of rare earth oxides, of which lanthanum oxide content is 83%, cerium dioxide content is 15%, and other rare earth content is 2%.

[0079] 3) Lanthanum chloride, cerium chloride, yttrium chloride, potassium carbonate, potassium hydroxide, fulvic acid, brown humic acid, black humic acid, ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate: analytical grade, all are chemical reagents.

[0080] Specific analysis methods:

[0081] 1) Content of sodium oxide, phosphorus, and rare earth oxide in molecular sieves: analyzed by X-ray fluorescence spectroscopy.

[0082] 2) Phosphorus and rare earth content in the filtrate: Detected using an ICP (Inductively Coupled Plasma Emission Spectrometer).

[0083] 3) Calculation method for rare earth utilization rate:

[0084]

[0085] Among them, C i - The concentration of rare earth elements added to the rare earth-containing solution (calculated as rare earth oxides), g / mL;

[0086] V - The volume of rare earth-containing solution added, in mL;

[0087] R i - The mass of solid rare earth added (based on rare earth oxides), g;

[0088] C o - The rare earth concentration (calculated as rare earth oxide) of the filtrate collected after filter cake filtration, g / mL;

[0089] V0 - The volume of filtrate collected after filtering the filter cake, in mL.

[0090] 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.

[0091] Comparative Example 1

[0092] A 1-baked molecular sieve sample was prepared according to the method provided in patent CN1485136A.

[0093] I. Filter cake formation

[0094] NaY molecular sieves were mixed with deionized water to prepare a slurry with a pH of 9 and a solid content of 100 g / L. The resulting slurry was heated to 70°C with stirring and poured into a Buchner funnel. Simultaneously, the filter cake in the Buchner funnel was evacuated to 0.05 MPa. Under vacuum, a filter cake of approximately 1.2 cm thick formed on the filter cloth of the Buchner funnel. The waste liquid in the filtration flask was then drained.

[0095] II. Ion Exchange

[0096] Maintain the vacuum in the filter flask. When there is almost no liquid on the surface of the filter cake, immediately and slowly add an aqueous solution of lanthanum chloride containing 50 g / L of lanthanum oxide at a temperature of 65°C. The addition rate should be such that there is always liquid on the surface of the filter cake until the weight ratio of lanthanum oxide to molecular sieve is 0.05.

[0097] III. Washing

[0098] Maintain the vacuum in the filter flask. When there is almost no liquid on the surface of the filter cake, immediately and slowly add deionized water at a temperature of 65°C. The rate at which the deionized water is added should be such that there is always liquid on the surface of the filter cake. Continue adding deionized water at a rate equivalent to three times the weight of the molecular sieve in the filter cake.

[0099] IV. Absorb dry

[0100] Continue evacuating until no more liquid flows out of the funnel, obtaining the dried filter cake and filtrate A.

[0101] V. Remove the filter cake and dry it.

[0102] The filter cloth was removed from the funnel, and the filter cake was removed from the filter cloth and dried at 140℃ to obtain a calcined molecular sieve. The sodium oxide content of the calcined molecular sieve was measured to be 4.6%, the rare earth content was 4.53%, and the rare earth content of filtrate A was 3208 ppm.

[0103] Then, the sample was prepared according to the method provided in patent CN1416951A.

[0104] The prepared molecular sieve, deionized water, and filtrate A were mixed and slurried to produce a molecular sieve slurry with a molecular sieve content of 120 g / L, wherein the amount of salt (i.e., rare earth chloride and sodium chloride contained in the filtrate) was 1.1 wt% of the molecular sieve. The obtained molecular sieve slurry was heated to 90°C and poured into a Buchner funnel. Simultaneously, the filter flask was evacuated to 0.07 MPa, forming a filter cake with a thickness of 10 mm on the filter cloth. When there was no liquid on the surface of the filter cake, an ammonium phosphate solution with a phosphorus content of 50 g / L and a temperature of 90°C was immediately added. The addition rate was ensured to prevent cracking on the surface of the filter cake, and the amount of ammonium phosphate solution was such that the weight ratio of phosphorus to molecular sieve was 0.1. When there was no liquid on the surface of the filter cake, deionized water at a temperature of 90°C was immediately added to wash the filter cake, with a weight ratio of deionized water to molecular sieve of 3. Then the filter cake and filtrate B were removed, and the filter cake was dried at 120°C to obtain rare earth Y-type molecular sieve D1. The D1 molecular sieve sample contained 1.0% sodium oxide, 125 ppm phosphorus in the filtrate, and 796 ppm rare earth elements.

[0105] Comparative Example 2

[0106] Samples were prepared according to patent CN108097288A.

[0107] Weigh 150g of dry NaY molecular sieve and add 750g of deionized water at 70℃. While stirring, add 3.2g of lanthanum chloride and stir at 70℃ for 60 minutes for exchange. Then add a 15% oxalic acid solution and continue stirring for 20 minutes. Wash and filter with 225g of deionized water at 70℃, discard the waste filtrate, and obtain a recycled filter cake. Add 525g of deionized water at 50℃ to the recycled filter cake and add 18.75g of lanthanum chloride while stirring. Stir at 50℃ for 60 minutes, then wash and filter with 225g of deionized water at 70℃ to obtain product filter cake A and recycled filtrate C. Add 150g of dry NaY molecular sieve to 750g of recycled filtrate C. In the process, the mixture is stirred at 70℃ for 60 minutes, then a 15% oxalic acid solution is added, and stirring continues for 20 minutes. The mixture is then washed and filtered with 225g of 70℃ deionized water, and the waste filtrate is discarded to obtain a recycled filter cake. 525g of 50℃ deionized water is added to the recycled filter cake, and 17.13g of lanthanum chloride is added while stirring. The mixture is stirred at 70℃ for 60 minutes, then washed and filtered with 225g of 50℃ deionized water to obtain product filter cake B and recycled filtrate D. Product filter cakes A and B are calcined in a muffle furnace at 580℃ for 3 hours to obtain rare earth Y molecular sieve D2, which has a sodium oxide content of 3.5%, a rare earth content of 23.5%, and a rare earth utilization rate of 97.9%.

[0108] Comparative Example 3

[0109] Samples were prepared according to patent CN200810223770.7.

[0110] Weigh 30 g of potassium hydroxide and dissolve it in 1200 g of distilled water. Stir well to prepare an alkaline solution and heat to 60 °C. Add 200 g of NaY molecular sieve (dry basis) to the above alkaline solution and stir at 60 °C for 10 hours. Filter, wash thoroughly with deionized water until the pH of the filtrate is less than 10, collect the sample and dry it.

[0111] Take 90 g of the above-mentioned alkali-treated product and add it together with 15.8 mL of mixed rare earth solution (RE2O3 content 285 g / L) to 450 g of distilled water and stir evenly. Then, stir and exchange at 80℃ for 1 h. During the exchange process, the pH value of the exchange slurry is adjusted to 3.5 using 1 mol / L hydrochloric acid solution and maintained. After the exchange is completed, filter, add ammonium phosphate solution at 90℃, the amount of ammonium phosphate solution is such that the weight ratio of phosphorus to molecular sieve is 0.20, and wash thoroughly with water. Then, remove the filter cake, dry it at 120℃, and calcine it at 600℃ for 2 h to obtain a first-calcined molecular sieve sample with a sodium oxide content of 4.8%, a RE2O3 content of 4.1%, a rare earth utilization rate of 82% in the first exchange process, and a phosphorus content of 17893 ppm in the filtrate.

[0112] Take 50g of the above-mentioned monocalculated molecular sieve sample and add it together with ammonium phosphate solution to 180g of distilled water. Stir well. The amount of ammonium phosphate solution should be such that the weight ratio of phosphorus to molecular sieve is 0.1. Then, stir and exchange at 80℃ for 3h. During the exchange process, adjust the pH of the exchange slurry to 4.2 with 1mol / L hydrochloric acid solution and maintain it. After the exchange is complete, filter and wash thoroughly with water to obtain molecular sieve sample D3, which has a sodium oxide content of 2.1%, a RE2O3 content of 3.8%, and a phosphorus content of 5124ppm in the second crosslinking filtrate.

[0113] Example 1

[0114] 1) Mix NaY molecular sieve, potassium hydroxide, potassium carbonate, fulvic acid and water to form a slurry, wherein the dry weight ratio of potassium hydroxide:potassium carbonate:fulvic acid:NaY molecular sieve is 0.012:0.005:0.05:1, to prepare a molecular sieve slurry with a molecular sieve content of 180 g / L. 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.

[0115] 2) Mix NaY molecular sieve with phosphorus-containing filtrate B (obtained from Comparative Example 1) and lanthanum chloride and slurry. Add lanthanum chloride to make the mass ratio of lanthanum oxide to molecular sieve 0.05, and prepare a molecular sieve slurry with a molecular sieve content of 120 g / L. Heat the obtained molecular sieve slurry to 70°C and stir for 1 hour. Pour it into the Buchner funnel onto the NaY filter cake from step 1). 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.

[0116] 3) When there is no liquid on the surface of the filter cake, immediately add ammonium phosphate solution at 90℃, ensuring the addition rate does not cause cracks to form on the filter cake surface. The amount of ammonium phosphate solution used should be such that the weight ratio of phosphorus to molecular sieve is 0.20. While there is still no liquid on the filter cake surface, immediately add deionized water at 80℃ to wash the filter cake, with a deionized water to molecular sieve weight ratio of 5. Obtain the product filter cake and filtrate E. Then, remove the filter cake and dry it at 120℃, followed by calcination at 600℃ for 2 hours to obtain a pre-calcined molecular sieve.

[0117] 4) Mix a batch of molecular sieve with water to make a molecular sieve slurry with a molecular sieve content of 110 g / L. 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 0.06 MPa to form a filter cake with a thickness of 10 mm on the filter cloth.

[0118] 5) When there is no liquid on the filter cake surface in step 4), immediately add an ammonium phosphate solution with a phosphorus content of 50 g / L and a temperature of 90°C. The addition speed should ensure that the filter cake surface does not crack. The amount of ammonium phosphate solution used should be such that the weight ratio of phosphorus to molecular sieve is 0.1. When there is no liquid on the filter cake surface, immediately add deionized water at a temperature of 90°C to wash the filter cake. The weight ratio of deionized water to molecular sieve is 5. Then remove the filter cake molecular sieve sample S1 and collect the filtrate F, which has a sodium oxide content of 0.9% and a phosphorus content of 1.5 ppm and a rare earth content of 6 ppm.

[0119] Example 2

[0120] The operation steps are the same as in Example 1, wherein in step 1), the dry weight ratio of potassium hydroxide: potassium carbonate: humic acid: NaY molecular sieve is 0.005:0.012:0.001:1, the NaY molecular sieve slurry content is 300 g / L, the slurry temperature is 15℃, the filter bottle vacuum degree is 0.08 MPa, and the filter cake thickness is 5 mm.

[0121] Step 2) Add phosphorus and rare earth filtrate F with a mass twice that of molecular sieve, add cerium chloride to make the mass ratio of cerium oxide to molecular sieve 0.10, slurry temperature 50℃, stir for 2h, filter flask vacuum degree 0.08 MPa, filter cake thickness 15 mm.

[0122] Step 3) Prepare an ammonium phosphate solution at 100℃, using an amount such that the weight ratio of phosphorus to molecular sieve is 0.05. Prepare deionized water at 100℃, with a weight ratio of deionized water to molecular sieve of 1. Obtain filter cake and filtrate G. Dry the filter cake at 200℃, calcine at 500℃ for 3 hours.

[0123] Step 4) The molecular sieve content of the molecular sieve slurry is 300 g / L, the slurry temperature is 100℃, the vacuum degree of the filter bottle is 0.02 MPa, and the filter cake thickness is 5 mm.

[0124] Step 5) The diammonium hydrogen phosphate solution has a phosphorus content of 100 g / L and a temperature of 100°C, with a phosphorus to molecular sieve weight ratio of 0.06. The deionized water is at a temperature of 20°C, with a deionized water to molecular sieve weight ratio of 15. Molecular sieve sample S2 and collected filtrate H are obtained, with a sodium oxide content of 1.1% and a phosphorus content of 1 ppm and a rare earth content of 3 ppm in filtrate G.

[0125] Example 3

[0126] The operation steps are the same as in Example 1, wherein in step 1), the dry weight ratio of potassium hydroxide: potassium carbonate: humic acid: NaY molecular sieve is 0.008:0.01:0.02:1, the NaY molecular sieve slurry content is 100 g / L, the slurry temperature is 100℃, the filter bottle vacuum degree is 0.02 MPa, and the filter cake thickness is 15 mm.

[0127] Step 2) Add phosphorus and rare earth filtrate H in a mass that is 10 times the mass of molecular sieve, add yttrium chloride to make the mass ratio of yttrium oxide to molecular sieve 0.01, slurry temperature 100℃, stir for 0.5h, filter flask vacuum degree 0.02 MPa, filter cake thickness 5 mm.

[0128] Step 3) Prepare an ammonium phosphate solution at 20°C, using an amount such that the weight ratio of phosphorus to molecular sieve is 0.005. Prepare deionized water at 20°C, with a weight ratio of deionized water to molecular sieve of 15. Obtain filter cake and filtrate I. Dry the filter cake at 20°C, calcine at 800°C for 1 hour.

[0129] Step 4) The molecular sieve content of the slurry 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.

[0130] Step 5) The ammonium dihydrogen phosphate solution has a phosphorus content of 15 g / L and a temperature of 20°C, with a phosphorus to molecular sieve weight ratio of 0.15. The deionized water is at a temperature of 100°C, with a deionized water to molecular sieve weight ratio of 15. Molecular sieve sample S3 and collected filtrate J are obtained, with a sodium oxide content of 1.0%, a phosphorus content of 0.8 ppm, and a rare earth content of 4 ppm.

[0131] Example 4

[0132] The operation steps are the same as in Example 1, wherein step 1) the dry weight ratio of potassium hydroxide: potassium carbonate: black humic acid and yellow humic acid: NaY molecular sieve is 0.011:0.007:0.006:1, the NaY molecular sieve slurry content is 180 g / L, the slurry temperature is 75℃, the filter bottle vacuum degree is 0.04 MPa, and the filter cake thickness is 8 mm.

[0133] Step 2) Add phosphorus-containing and rare earth filtrate J in a mass 5 times that of the molecular sieve. Add lanthanum chloride in a mass ratio of lanthanum oxide to molecular sieve of 0.06. Set the slurry temperature to 70°C, stir for 1.5 h, maintain a vacuum of 0.04 MPa in the filter flask, and make the filter cake thickness 13 mm. Add lanthanum-rich rare earth chloride to the NaY molecular sieve slurry. The amount of rare earth salt added is based on rare earth oxides, and the weight ratio of rare earth oxides to molecular sieve is 0.04.

[0134] Step 3) Prepare an ammonium phosphate solution at 50°C, using an amount such that the weight ratio of phosphorus to molecular sieve is 0.17. Use deionized water at 40°C, with a weight ratio of deionized water to molecular sieve of 8. Obtain filter cake and filtrate K. Dry the filter cake at 60°C, calcine at 600°C for 1.5 hours.

[0135] Step 4) The molecular sieve content of the slurry 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.

[0136] Step 5) The ammonium dihydrogen phosphate solution has a phosphorus content of 75 g / L and a temperature of 45°C, with a phosphorus to molecular sieve weight ratio of 0.07. The deionized water is at a temperature of 60°C, with a deionized water to molecular sieve weight ratio of 9. The filter cake is dried at 200°C and then calcined at 500°C for 1 hour to obtain molecular sieve sample S4 and collected filtrate L, which has a sodium oxide content of 1.2%, a phosphorus content of 3 ppm, and a rare earth content of 1 ppm.

[0137] The results of molecular sieve samples S1 to S4 obtained in Examples 1-4 show that the phosphorus- and rare earth-containing Y-type molecular sieves obtained by the method of this invention have a higher rare earth introduction amount than conventional phosphorus and rare earth Y-type molecular sieves, and the rare earth introduction amount is controllable. Compared with molecular sieve D1 prepared by the comparative example using existing patented technology, the molecular sieve prepared by the examples of this invention has a sodium oxide content comparable to the comparative molecular sieve, but there is virtually no loss of phosphorus and rare earth during the molecular sieve preparation process, and the utilization rate of phosphorus and rare earth reaches over 99%. In contrast, the rare earth content of molecular sieve D1 prepared by the comparative example is significantly lower than the feed amount, and a large amount of phosphorus and rare earth is not exchanged onto the molecular sieve during the exchange process and is lost with the filtrate during filtration, resulting in low utilization of phosphorus and rare earth. If the phosphorus and rare earth entering the filtrate are not treated, they will also cause environmental pollution. As can be seen from the molecular sieve sample S1 obtained in the example and the rare earth Y molecular sieve D2 obtained in the comparative example, under the same rare earth content, the phosphorus-containing and rare earth-containing Y molecular sieve prepared by the method provided by the present invention can take into account the utilization rate of phosphorus and rare earth and the sodium oxide content of molecular sieve, without affecting the subsequent use of molecular sieve, and has a good prospect for industrial application.

[0138] 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 phosphorus- and rare earth-containing Y-type molecular sieve, characterized in that, Includes the following steps: Step 1: Form a NaY molecular sieve filter cake layer from the NaY molecular sieve slurry; Step 2: Mix NaY molecular sieve with phosphorus-containing filtrate and rare earth salt solution to form RE-NaY molecular sieve filter cake layer on the NaY molecular sieve filter cake layer, and obtain composite filter cake; Step 3: The phosphate solution is subjected to ion exchange with the composite filter cake obtained in Step 2, followed by water washing and calcination to obtain a Y-type molecular sieve containing phosphorus and rare earth elements. The slurry of the NaY molecular sieve includes NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid and water. The ion exchange and water washing are performed at least once.

2. The preparation method according to claim 1, characterized in that, The alkali metal hydroxide is potassium hydroxide, and the carbonate is potassium carbonate; the dry weight ratio of potassium hydroxide:potassium carbonate:humic acid:NaY molecular sieve is 0.005-0.012:0.005-0.012:0.001-0.05:

1.

3. The preparation method according to claim 1, characterized in that, The humic acid is at least one of fulvic acid, brown humic acid, and black humic acid.

4. The preparation method according to claim 1, characterized in that, The rare earth element in the rare earth salt is selected from at least one of lanthanum, cerium, praseodymium, neodymium, and yttrium; the phosphate solution is selected from at least one of ammonium phosphate solution, diammonium hydrogen phosphate solution, and ammonium dihydrogen phosphate solution.

5. The preparation method according to claim 1, characterized in that, In step 2, the phosphorus-containing filtrate is the filtrate recovered in step 2 or step 3, or the phosphorus-containing filtrate collected or prepared by other processes, and the mass ratio of the phosphorus-containing filtrate to NaY molecular sieve is 2:10; the rare earth salt is calculated as rare earth oxide, and its addition amount is 0.01-0.10 of the mass ratio of NaY molecular sieve.

6. The preparation method according to claim 1, characterized in that, The preparation method is carried out on a belt filter; the belt filter includes at least one cake forming zone, at least one ion exchange zone and at least one water washing zone.

7. The preparation method according to claim 1, characterized in that, In step 3, the phosphate solution is added from the top of the composite filter cake and flows through the composite filter cake to perform ion exchange; the weight ratio of the phosphate solution in step 3 to the NaY molecular sieve in step 2 is 0.005-0.05, calculated as phosphorus element.

8. The preparation method according to claim 1, characterized in that, Step 3 is as follows: The phosphate solution is subjected to a first ion exchange with the composite filter cake obtained in Step 2, followed by a first calcination to obtain a calcined molecular sieve; the calcined molecular sieve is slurried with water to form a filter cake, and the phosphate solution is subjected to a second ion exchange with the filter cake, followed by a second calcination to obtain a Y-type molecular sieve containing phosphorus and rare earth elements; the weight ratio of the phosphate solution to the calcined molecular sieve in Step 3 is 0.02-0.15, calculated based on phosphorus element.

9. The preparation method according to claim 8, characterized in that, The filtrate from step 2, which is formed during the RE-NaY molecular sieve filter cake layer, the filtrate from step 3, which is formed during the first ion exchange, the filtrate from the slurry of the molecular sieve and water, and the filtrate from the second ion exchange, shall be used as the phosphorus-containing filtrate from step 2.

10. A phosphorus- and rare-earth-containing Y-type molecular sieve obtained by the preparation method according to any one of claims 1-9.

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