A core-shell structured catalyst and a preparation method and application thereof

Abstract

The application provides a core-shell structure catalyst and a preparation method and application thereof. The core-shell structure catalyst comprises a core and a core shell covering at least part of the surface of the core. The core comprises a Y-type molecular sieve containing phosphorus and rare earth metals, and the core shell comprises an isooctanoate. The core-shell structure catalyst has excellent performance in terms of coking performance and heavy oil conversion capacity.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a core-shell structured catalyst, its preparation method, and its application. Background Technology

[0002] With the increasing depletion of petroleum resources, the proportion of heavy oil components in feedstocks is rising. The main method for processing heavy oil is catalytic cracking. During catalytic cracking, large heavy oil molecules are broken down into different types of smaller molecules by a catalytic cracking catalyst. Molecular sieves, due to their strong acidic centers and good hydrothermal stability, are widely used in catalytic cracking.

[0003] Y-type molecular sieves are aluminosilicates with a special crystalline structure and have the advantage of high cracking activity. However, due to the microporous structure of Y-type molecular sieves, they are prone to thermal cracking and coking reactions during catalytic cracking, which can lead to catalyst deactivation. In addition, heavy oil components often contain a large amount of heavy metals such as vanadium and nickel, which can easily poison the molecular sieve and affect the catalyst's heavy oil conversion ability.

[0004] Currently, coated molecular sieve composite materials are often used to replace simple molecular sieves to improve their performance. For example, patent document CN105983429A discloses a heavy oil catalytic cracking catalyst and its preparation method, which uses a composite material of mesoporous alumina molecular sieve coated with microporous molecular sieve as the catalyst; patent document CN113830778A discloses a ZSM-5 / β core-shell molecular sieve and its synthesis method and application, which has a ZSM-5 molecular sieve core phase and a β molecular sieve shell layer; patent document CN101108736A discloses a method for preparing a type of Y-type molecular sieve that has both micropores and mesopores, which coats a mesoporous Y-type molecular sieve onto the surface of a microporous zeolite Y-type molecular sieve to form a core-mantle structure; and patent document CN101618333B discloses a Y / crystalline silica composite molecular sieve and its preparation method, which has a core-shell structure with a Y molecular sieve as the core and a pure silica molecular sieve as the shell. However, the above methods fall far short of the required level of improvement in the coking performance and heavy oil conversion capacity of molecular sieves.

[0005] Therefore, how to provide a catalyst with excellent coking performance and strong heavy oil conversion capability is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] This invention provides a core-shell structured catalyst that exhibits excellent performance in terms of coking properties and heavy oil conversion capacity.

[0007] The present invention also provides a method for preparing a core-shell structured catalyst, which can simply and efficiently obtain the above-mentioned core-shell structured catalyst.

[0008] The present invention also provides a method for heavy oil catalytic cracking, which, by using the above-mentioned core-shell structure catalyst, can improve the heavy oil conversion rate and reduce the coke yield.

[0009] In a first aspect, the present invention provides a core-shell structured catalyst, comprising a core and a core shell covering at least a portion of the surface of the core; wherein the core comprises a Y-type molecular sieve containing phosphorus and rare earth metals, and the core shell comprises isooctanoate.

[0010] The core-shell structured catalyst as described above, wherein the mass content of the isooctanoate in the core-shell structured catalyst is 0.01-1%.

[0011] The core-shell structured catalyst as described above, wherein the isooctanoate comprises at least one of yttrium isooctanoate, cerium isooctanoate, and antimony isooctanoate.

[0012] The core-shell structured catalyst as described above is prepared by a method comprising the following process: coating phosphorus-containing and rare earth metal-containing Y-type molecular sieve microspheres with isooctanoate to obtain the core-shell structured catalyst.

[0013] The core-shell structured catalyst described above, wherein the phosphorus- and rare earth metal-containing Y-type molecular sieve microspheres are prepared by a method comprising the following process:

[0014] The first NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid and water were mixed and pretreated to obtain a pretreated molecular sieve.

[0015] The pretreated molecular sieve is subjected to a first ion exchange treatment in a slurry containing a second NaY molecular sieve, a phosphorus-containing filtrate, and rare earth metal salts to obtain a first exchange product.

[0016] The first exchange product is subjected to a second ion exchange treatment in a phosphate solution to obtain a second exchange product.

[0017] After subjecting the second exchange product to a first drying and a first calcination treatment, a Y-type molecular sieve containing phosphorus and rare earth metals is obtained.

[0018] The phosphorus- and rare earth metal-containing Y-type molecular sieve, clay, binder, and water are mixed, and then spray-dried and subjected to a second calcination treatment to obtain phosphorus- and rare earth metal-containing Y-type molecular sieve microspheres.

[0019] A second aspect of the present invention provides a method for preparing the core-shell structured catalyst described in the first aspect, comprising the following steps: coating phosphorus- and rare earth metal-containing Y-type molecular sieve microspheres with isooctanoate to obtain the core-shell structured catalyst.

[0020] The preparation method described above further includes: mixing the first NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid and water, and pretreating them to obtain a pretreated molecular sieve;

[0021] The pretreated molecular sieve is subjected to a first ion exchange treatment in a slurry containing a second NaY molecular sieve, a phosphorus-containing filtrate, and rare earth metal salts to obtain a first exchange product.

[0022] The first exchange product is subjected to a second ion exchange treatment in a phosphate solution to obtain a second exchange product.

[0023] After subjecting the second exchange product to a first drying and a first calcination treatment, a Y-type molecular sieve containing phosphorus and rare earth metals is obtained.

[0024] The phosphorus- and rare earth metal-containing Y-type molecular sieve, clay, binder, and water are mixed, and then spray-dried and subjected to a second calcination treatment to obtain phosphorus- and rare earth metal-containing Y-type molecular sieve microspheres.

[0025] The core-shell structured catalyst as described above, wherein the humic acid includes at least one of fulvic acid, brown humic acid, and black humic acid; and / or,

[0026] The alkali metal hydroxide includes at least one of sodium hydroxide and potassium hydroxide; and / or,

[0027] The carbonate includes at least one of potassium carbonate and sodium carbonate; and / or,

[0028] The rare earth metal salt is selected from at least one of lanthanum salt, cerium salt, praseodymium salt, neodymium salt, and yttrium salt; and / or,

[0029] The phosphate in the phosphate solution is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate; and / or,

[0030] The clay is selected from at least one of kaolin, halloysite, and montmorillonite; and / or,

[0031] The binder is selected from at least one of alumina sol, silica sol, and boehmite; and / or,

[0032] The mass ratio of the alkali metal hydroxide, carbonate, humic acid, and first NaY molecular sieve is (0.005–0.012):(0.005–0.012):(0.001–0.05):1; and / or,

[0033] The rare earth metal salt, calculated as rare earth metal oxide, has a mass ratio of (0.01–0.1):1 with the second NaY molecular sieve; and / or,

[0034] The phosphate solution, calculated as elemental phosphorus, has a mass ratio of (0.005–0.15):1 with the second NaY molecular sieve; and / or,

[0035] The conditions for the first ion exchange treatment are: temperature 50–100℃, time 0.5–2 h; and / or,

[0036] The temperature for the first drying step is 20–200℃, and the temperature for spray drying is 100–200℃; and / or,

[0037] The conditions for the first roasting are: temperature 500–800℃, time 1–3 hours; and / or,

[0038] The conditions for the second roasting are: temperature 300-500℃, time 15-60min.

[0039] A third aspect of the present invention provides a method for catalytic cracking of heavy oil, wherein a catalyst is brought into contact with feedstock oil under catalytic cracking conditions to react, and the catalyst is the aforementioned core-shell structure catalyst.

[0040] The implementation of this invention has at least the following beneficial effects:

[0041] The core-shell structured catalyst provided by this invention uses a Y-type molecular sieve containing phosphorus and rare earth metals as the core and isooctanoate as the core and shell. When this core-shell structured catalyst is applied to the catalytic cracking of feedstock containing heavy oil, the feedstock is adsorbed onto the surface of the catalyst. This allows the feedstock to first contact the core and shell, generating small molecule olefins. Then, the small molecule olefins contact the core, undergoing a catalytic cracking reaction to generate a large number of carbocations, promoting the continuous catalytic cracking reaction and inhibiting the thermal cracking and coking reaction, thereby reducing coke yield and increasing heavy oil conversion rate. In addition, heavy metals such as vanadium and nickel in the heavy oil first react with the core and shell isooctanoate to form stable compounds. These compounds are stably deposited on the surface of the catalyst, avoiding the influence of heavy metals on the catalyst's performance and improving the heavy oil conversion rate.

[0042] The method for preparing the core-shell structured catalyst provided by this invention can produce the above-mentioned core-shell structured catalyst and has the advantages of simple operation, high efficiency and ease of use.

[0043] The heavy oil catalytic cracking method provided by this invention, by employing the above-mentioned core-shell structure catalyst, can improve the heavy oil conversion rate and reduce the coke yield. Attached Figure Description

[0044] Figure 1This is a device diagram of a first belt filter according to an embodiment of the present invention;

[0045] Figure 2 This is a diagram of a second belt filter according to an embodiment of the present invention.

[0046] Explanation of reference numerals in the attached figures:

[0047] 3-First filter cloth; 4-NaY molecular sieve filter cake forming zone; 7-One-cross molecular sieve filter cake forming zone;

[0048] 11-First ion exchange zone; 14-First water washing zone; 25-Second water washing zone; 18-Dual-cross molecular sieve filter cake forming zone; 21-Second ion exchange zone;

[0049] 8 - First liquid receiver; 22 - Second liquid receiver;

[0050] 1-First pulping tank; 5-Second pulping tank; 15-Third pulping tank;

[0051] 2 - First pipeline; 6 - Second pipeline; 10 - Third pipeline; 13 - Fourth pipeline; 16 - Fifth pipeline; 20 - Sixth pipeline; 24 - Seventh pipeline; 26 - Eighth pipeline;

[0052] 9 - First container; 12 - Second container; 19 - Third container; 23 - Fourth container. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0054] In a first aspect, the present invention provides a core-shell structured catalyst, comprising a core and a core-shell covering at least a portion of the surface of the core; wherein the core comprises a Y-type molecular sieve containing phosphorus and rare earth metals, and the core-shell comprises isooctanoate.

[0055] According to the technical solution provided by the present invention, when the above-mentioned core-shell structure catalyst is used in the catalytic cracking reaction of feedstock containing heavy oil, the core-shell structure catalyst not only exhibits excellent coking performance and heavy oil conversion capacity. Based on this phenomenon, the inventors analyzed that it may be due to the following: On the one hand, since the catalytic cracking of feedstock involves carbocation reactions, when the core-shell structure catalyst is applied to the catalytic cracking of feedstock containing heavy oil, the feedstock is adsorbed on the surface of the catalyst, so that the feedstock first contacts the core and shell to generate small molecule olefins. Then, the small molecule olefins contact the core and undergo catalytic cracking to generate a large number of carbocations, which promotes the continuous progress of the catalytic cracking reaction, inhibits the thermal cracking coking reaction, thereby improving coking performance, reducing coke yield, and increasing heavy oil conversion rate. On the other hand, heavy metals such as vanadium and nickel in the heavy oil first react with the core and shell isooctanoate to form stable compounds. These compounds are stably deposited on the surface of the catalyst, preventing the heavy metals from migrating within and between catalyst particles and causing physicochemical reactions between the heavy metals and the catalyst, which would damage the crystal structure of the catalyst, further improving the heavy oil conversion rate.

[0056] It should be noted that the present invention does not limit the number of core and shell layers, as long as the core and shell cover the surface of the core.

[0057] This invention does not limit the proportions of the components in the core-shell structured catalyst. In one embodiment, the mass content of isooctanoate in the core-shell structured catalyst is 0.01% to 1%.

[0058] This invention does not limit the specific category of isooctanoates, and can be any conventional isooctanoate compound. In one embodiment, isooctanoates include at least one of yttrium isooctanoate, cerium isooctanoate, and antimony isooctanoate.

[0059] This invention does not limit the specific preparation process of the core-shell structured catalyst, as long as the core-shell structured catalyst can be obtained. In one embodiment, the core-shell structured catalyst can be prepared by a method including the following process: coating phosphorus-containing and rare earth metal-containing Y-type molecular sieve microspheres with isooctanoate to obtain the core-shell structured catalyst.

[0060] This invention does not limit the preparation process of Y-type molecular sieve microspheres containing phosphorus and rare earth metals, as long as the Y-type molecular sieve containing phosphorus and rare earth metals can be formed into microsphere particles. In one embodiment, Y-type molecular sieve microspheres containing phosphorus and rare earth metals can be prepared by a method comprising the following steps: mixing a first NaY molecular sieve, an alkali metal hydroxide, a carbonate, humic acid, and water, pretreating the mixture, and then filtering it first to obtain a pretreated molecular sieve; subjecting the pretreated molecular sieve to a first ion exchange treatment in a slurry containing a second NaY molecular sieve, a phosphorus-containing filtrate, and a rare earth metal salt to obtain a first exchange product; subjecting the first exchange product to a second ion exchange treatment in a phosphate solution, filtering the mixture to obtain a second exchange product and a first filtrate; returning the first filtrate to the first ion exchange treatment; subjecting the second exchange product to a first drying and a first calcination treatment to obtain a Y-type molecular sieve containing phosphorus and rare earth metals; and mixing the Y-type molecular sieve containing phosphorus and rare earth metals, clay, a binder, and water, spray drying the mixture, and then calcining it second to obtain Y-type molecular sieve microspheres containing phosphorus and rare earth metals.

[0061] The second aspect of the present invention provides a method for preparing the core-shell structured catalyst of the first aspect, comprising the following steps: coating phosphorus-containing and rare earth metal-containing Y-type molecular sieve microspheres with isooctanoate to obtain the core-shell structured catalyst.

[0062] This invention does not limit the specific form of the coating process, as long as the core shell covers at least a portion of the core surface. For example, the coating process can be at least one of precipitation, impregnation, and microwave methods; the impregnation method can be an equal-volume impregnation method. It should be noted that the coating process can be performed once or multiple times, depending on actual needs.

[0063] This invention does not limit the preparation process of Y-type molecular sieve microspheres containing phosphorus and rare earth metals, as long as the Y-type molecular sieve containing phosphorus and rare earth metals can form microsphere particles. In one embodiment, Y-type molecular sieve microspheres containing phosphorus and rare earth metals can be prepared by a method including the following steps: mixing a first NaY molecular sieve, an alkali metal hydroxide, a carbonate, humic acid, and water, pretreating the mixture, and then filtering it first to obtain a pretreated molecular sieve; subjecting the pretreated molecular sieve to a first ion exchange treatment in a solution containing a second NaY molecular sieve, a phosphorus-containing filtrate, and a rare earth metal salt to obtain a first exchange product; subjecting the first exchange product to a second ion exchange treatment in a phosphate solution to obtain a second exchange product; subjecting the second exchange product to a first drying and a first calcination treatment to obtain a Y-type molecular sieve containing phosphorus and rare earth metals; and mixing the Y-type molecular sieve containing phosphorus and rare earth metals, clay, a binder, and water, spray drying the mixture, and then calcining it second to obtain Y-type molecular sieve microspheres containing phosphorus and rare earth metals.

[0064] In the above process, by controlling the order of addition of each component, it is beneficial to obtain Y-type molecular sieve microspheres containing phosphorus and rare earth metals. When these microspheres are used to prepare core-shell structured catalysts, the core-shell structured catalysts can have advantages such as high catalytic activity and high stability. When applied to the catalytic cracking of heavy oil, the conversion rate of heavy oil can be improved.

[0065] During the pretreatment process, alkali metal hydroxides and carbonates can remove amorphous silicon and aluminum from the surface of the first NaY molecular sieve and ensure the integrity of the crystals of the first NaY molecular sieve, which is beneficial for subsequent ion exchange treatment.

[0066] Meanwhile, during the pretreatment process, in the alkaline system formed by mixing the first NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid, and water, humic acid combines with alkali metal to form sodium humate or potassium humate. In subsequent ion exchange treatment, sodium humate and potassium humate can synthesize organic rare earth complexes with rare earth metal ions in rare earth metal salts through adsorption, exchange, and complexation, thereby limiting the migration of rare earth metals and reducing their loss. In addition, humic acid also has a phosphorus-fixing effect, making it less likely for phosphorus to be lost, which is beneficial for obtaining Y-type molecular sieves containing phosphorus and rare earth metals and improving the catalytic performance of the molecular sieve.

[0067] This invention does not limit the specific operational steps of the pretreatment. For example, the pretreatment can be carried out on a belt filter. For instance, the first NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid and water are mixed and slurried, and the mixture is pretreated on a belt filter. After filtration, a pretreated molecular sieve (also called NaY molecular sieve filter cake) is obtained, and the filtrate is collected.

[0068] This invention does not limit the specific operational steps of the first ion exchange treatment. For example, the first ion exchange treatment can be carried out on a belt filter, so that the first ion exchange treatment and filtration are performed simultaneously. Specifically, the pretreated molecular sieve can be placed on the belt filter, so that the first exchange liquid passes through the pretreated molecular sieve from one side and undergoes the first ion exchange reaction with the pretreated molecular sieve. When there is no liquid on the surface of the pretreated molecular sieve, a filter cake is obtained. Then, sufficient washing water is sprinkled on it for washing, and finally the first exchange product and the first exchange waste liquid (also called the first filtrate) are obtained. The first exchange liquid includes at least phosphorus-containing filtrate and rare earth metal salts. Specifically, the first exchange liquid can be a solution containing phosphorus-containing filtrate and rare earth metal salts, or it can be a solution containing a second NaY molecular sieve, phosphorus-containing filtrate, and rare earth metal salts.

[0069] When the first exchange solution is a solution containing a second NaY molecular sieve, a phosphorus-containing filtrate, and a rare earth metal salt, in one embodiment, the first NaY molecular sieve, an alkali metal hydroxide, a carbonate, humic acid, and water are mixed and pretreated to obtain a pretreated molecular sieve; the second NaY molecular sieve, the phosphorus-containing filtrate, and the rare earth metal salt are mixed and slurried to form the first exchange solution; the pretreated molecular sieve undergoes a first ion exchange reaction in the first exchange solution. The rare earth metal salt can be added all at once or in batches. This invention does not limit the mass ratio of the first NaY molecular sieve to the second NaY molecular sieve.

[0070] Specifically, a second NaY molecular sieve, phosphorus-containing filtrate, and rare earth metal salts are mixed and slurried to form a first exchange solution. The pretreated molecular sieve is placed on a belt filter, allowing the first exchange solution to pass through it from one side. Simultaneously, the second NaY molecular sieve in the first exchange solution undergoes a first ion exchange reaction with the phosphorus-containing filtrate and rare earth metal salts, forming an RE-NaY molecular sieve layer on the pretreated molecular sieve. After filtration, a filter cake is obtained, which is then washed with sufficient washing water for a first water wash, ultimately yielding the first exchange product and the first filtrate. In this process, the second NaY molecular sieve in the first exchange solution undergoes ion exchange with the phosphorus-containing filtrate and rare earth metal salts, forming an RE-NaY molecular sieve layer on the pretreated molecular sieve. Simultaneously, the pretreated molecular sieve adsorbs excess phosphorus and rare earth metal ions, significantly increasing the phosphorus and rare earth metal loading. This allows for the recovery and utilization of phosphorus and rare earth metals during the first ion exchange process, further reducing their loss and shortening the reaction time.

[0071] Furthermore, the first filtrate can be reused as a phosphorus-containing filtrate for the first ion exchange treatment, which is beneficial for the recovery and utilization of rare earth metals and phosphorus in the filtrate.

[0072] This invention does not limit the specific operational steps of the second ion exchange treatment. For example, the second ion exchange treatment can be carried out on a belt filter, thus allowing the second ion exchange treatment and filtration to occur simultaneously. Specifically, for example, in one embodiment, a phosphate solution (also referred to as the second exchange liquid) undergoes a second ion exchange reaction with the first exchange product. When there is no liquid on the surface of the first exchange product, a second ion exchange filter cake is obtained. Then, sufficient washing water is sprinkled on it for a second water wash. When there is no liquid on the surface of the second ion exchange filter cake, the second exchange product and the second exchange waste liquid (also referred to as the second filtrate) are finally obtained.

[0073] Furthermore, the second filtrate can be reused as a phosphorus-containing filtrate for the first ion exchange treatment, which is beneficial for the recovery and utilization of rare earth metals and phosphorus in the filtrate.

[0074] This invention does not limit the number of times the second ion exchange treatment is performed; it can be once or multiple times. In one embodiment, the first exchange product undergoes a first second ion exchange treatment in a first phosphate solution. After filtration and washing, a second exchange product and a third filtrate are obtained. The second exchange product is dried and calcined to obtain a calcined molecular sieve. The calcined molecular sieve is mixed with water and slurryed to form a calcined molecular sieve filter cake. The calcined molecular sieve filter cake undergoes a second second ion exchange treatment (also referred to as a third ion exchange treatment) in a second phosphate solution. After filtration and washing, a third exchange product and a third exchange waste liquid (also referred to as a fourth filtrate) are obtained. The third exchange product is dried and calcined to obtain a phosphorus- and rare earth-containing Y-type molecular sieve. The above process is beneficial to improving the phosphorus loading and utilization rate. The first phosphate solution and the second phosphate solution, calculated based on elemental phosphorus, have a mass ratio of (0.005-0.05):1 for the first phosphate solution and (0.02-0.15):1 for the second phosphate solution and the calcined molecular sieve.

[0075] Furthermore, the third and / or fourth filtrates can be returned as phosphorus-containing filtrates for the first ion exchange treatment, which is beneficial for the recovery and utilization of rare earth metals and phosphorus in the filtrates.

[0076] It should be noted that phosphorus-containing filtrate includes, but is not limited to, the phosphorus-containing filtrate collected during the process. Furthermore, since the first, second, third, and fourth filtrates still contain unused rare earth metal ions and phosphorus, each of these filtrates can be independently used as a phosphorus-containing filtrate in the first ion exchange treatment. In addition, the filtrate produced when a calcined molecular sieve is mixed with water and pulped to form a calcined molecular sieve filter cake can also be used as a phosphorus-containing filtrate.

[0077] The present invention does not limit the specific type of belt filter, such as a horizontal vacuum belt filter, which includes at least a cake forming zone, at least a ion exchange zone and at least a water washing zone.

[0078] In this invention, Y-type molecular sieves containing phosphorus and rare earth metals, clay, binder, and water are first mixed and slurried for 15-90 minutes to obtain a mixed slurry. The slurry is then spray-dried to form microspheres. After a second calcination treatment, Y-type molecular sieve microspheres containing phosphorus and rare earth metals are obtained, which is beneficial for subsequent coating treatment to form a core-shell structure catalyst.

[0079] It should be noted that in this invention, the third exchange product can be dried and calcined to obtain a Y-type molecular sieve containing phosphorus and rare earth metals; then, the Y-type molecular sieve containing phosphorus and rare earth metals, a binder, clay, and water are mixed to prepare microspheres. Alternatively, the third exchange product can be washed and filtered to obtain a Y-type molecular sieve containing phosphorus and rare earth metals; then, the Y-type molecular sieve containing phosphorus and rare earth metals, a binder, clay, and water are mixed, and then dried and calcined to obtain a modified Y-type molecular sieve catalyst. The modified Y-type molecular sieve catalyst comprises the following components by mass: 25-70 wt% Y-type molecular sieve containing phosphorus and rare earth metals, 20-60 wt% clay, and 3-20 wt% binder. The above methods are more advantageous in simplifying the preparation process.

[0080] This invention does not limit the specific selection of each raw material. For example, humic acid includes at least one of fulvic acid, brown humic acid, and black humic acid; alkali metal hydroxides include at least one of sodium hydroxide and potassium hydroxide; carbonates include at least one of potassium carbonate and sodium carbonate; rare earth metal salts are selected from at least one of lanthanum salts, cerium salts, praseodymium salts, neodymium salts, and yttrium salts, such as rare earth metal chloride salts and rare earth metal nitrate salts; phosphates in phosphate solutions are selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate; clay is selected from at least one of kaolin, halloysite, and montmorillonite; and the binder is selected from at least one of alumina sol, silica sol, and boehmite.

[0081] The present invention does not limit the mass ratio of each raw material. For example, the mass ratio of alkali metal hydroxide, carbonate, humic acid and NaY molecular sieve is (0.005-0.012):(0.005-0.012):(0.001-0.05):1; the mass ratio of phosphorus-containing filtrate to second NaY molecular sieve is (2-10):1, more preferably (3-6):1; the rare earth metal salt is calculated as rare earth metal oxide, and the mass ratio of rare earth metal salt to second NaY molecular sieve is (0.01-0.1):1, more preferably (0.05-0.1):1.

[0082] This invention does not limit the preparation parameters of each step. For example, the conditions for the first ion exchange treatment are: temperature 50–100°C, time 0.5–2 h; the conditions for the first and second water washings are each independently selected from: temperature 20–100°C, and the mass ratio of water to the molecular sieve to be washed is (1–15):1; the pretreatment temperature is 10–100°C; the first drying temperature is 20–200°C; and the spray drying temperature is 100–200°C; the conditions for the first calcination are: temperature 500–800°C, time 1–3 h; and the conditions for the second calcination are: temperature 300–500°C, time 15–60 min. The first drying temperature can further be 100–150°C, the first calcination conditions can further be 600–700°C, time 2–3 h, the first and second water washing temperatures can further be 60–80°C, and the mass ratio of water to the molecular sieve to be washed can further be (3–5):1.

[0083] This invention does not limit the specific source of NaY molecular sieves; they can be commercially purchased or prepared using conventional methods. For example, referring to the method disclosed in patent document CN103449468B, the specific preparation method of NaY molecular sieves includes: mixing water glass, sodium aluminate, and deionized water, and aging at 15-70℃ 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℃ for 0.1-80 hours; and then adding peroxide to the crystallized silica-alumina gel to allow the O2 in the peroxide to... 2- The molar ratio of sodium oxide to Al2O3 in the gel is (0.05-20):1, and further crystallization is carried out for 5-20 hours to obtain NaY molecular sieve. The sodium oxide content in the NaY molecular sieve includes, but is not limited to, 9-15 wt%.

[0084] In the implementation of this invention, the preparation of the above-mentioned Y-type molecular sieve containing phosphorus and rare earth metals can be achieved using a first belt filter and a second belt filter, as follows: Figure 1 and Figure 2As shown, the first belt filter includes a NaY molecular sieve cake forming zone 4, a cross-linked molecular sieve cake forming zone 7, a first ion exchange zone 11, a first washing zone 14 connected in series via a first filter cloth 3, and a first liquid receiver 8 for receiving filtrate; the NaY molecular sieve cake forming zone 4 includes a first pulping tank 1 and a first pipeline 2 connecting the first pulping tank 1 and the first filter cloth 3; the cross-linked molecular sieve cake forming zone 7 includes a second pulping tank 5 and a second pipeline 6 connecting the second pulping tank 5 and the first filter cloth 3; the first ion exchange zone 11 includes a first container 9 and a third pipeline 10 connecting the first container 9 and the first filter cloth 3; the first washing zone 14 includes a second container 12. A fourth pipeline 13 connecting the second container 12 and the first filter cloth 3; the second belt filter includes a di-cross molecular sieve cake forming zone 18, a second ion exchange zone 21, a second water washing zone 25 connected in series through the second filter cloth 17, and a second liquid receiver 22 for receiving the filtrate; the di-cross molecular sieve cake forming zone 18 includes a third pulping tank 15 and a fifth pipeline 16 connecting the third pulping tank 15 and the second filter cloth 17; the second ion exchange zone 21 includes a third container 19 and a sixth pipeline 20 connecting the third container 19 and the second filter cloth 17; the second water washing zone 25 includes a fourth container 23 and a seventh pipeline 24 connecting the fourth container 23 and the second filter cloth 17. The specific preparation method is as follows:

[0085] I. Preprocessing

[0086] A slurry (temperature 10-100℃, preferably 50-90℃) formed from NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid, and water is continuously loaded from the first pulping tank 1 through the first pipeline 2 onto the first filter cloth 3 of a horizontal vacuum belt filter. The first filter cloth moves continuously into the NaY molecular sieve filter cake forming zone 4. A first liquid receiver 8 is located below the first filter cloth 3. The first liquid receiver 8 is evacuated, and under vacuum, the liquid in the slurry on the first filter cloth 3 passes through the first filter cloth 3 and enters the first liquid receiver 8. Simultaneously, the NaY slurry on the first filter cloth 3 forms a NaY molecular sieve filter cake. The loading rate of the NaY slurry should ensure that the thickness of the formed NaY molecular sieve filter cake is 0.5-1.5 cm, preferably 0.8-1.5 cm. The vacuum degree in the first liquid receiver 8 ensures that the filter cake surface is free of cracks. The vacuum degree in the first liquid receiver 8 is, for example, but not limited to, 0.02-0.08 MPa, preferably 0.05-0.08 MPa.

[0087] II. First Ion Exchange Treatment

[0088] The first exchange solution (temperature 50-100℃) is continuously loaded from the second slurry tank 5 onto the NaY molecular sieve filter cake of the horizontal vacuum belt filter via the second pipeline 6, and moves with the first filter cloth into the first-stage molecular sieve filter cake forming zone 7. The phosphorus-containing filtrate in the first exchange solution can be provided by the second liquid receiver 22 via the eighth pipeline 26 during the second ion exchange process (described later), or by the filtrate collected in the first liquid collector 8. This reduces water consumption and allows for the recovery of phosphorus from the second-stage ion exchange filtrate, reducing wastewater discharge and improving phosphorus utilization. Simultaneously, the first-stage molecular sieve slurry on the first filter cloth 3 forms a first-stage filter cake. The loading rate of the first exchange solution should ensure that the thickness of the first-stage filter cake is 0.5-1.5 cm, preferably 0.8-1.5 cm. After filtration and washing, the first exchange product is obtained.

[0089] III. Second Ion Exchange Treatment

[0090] As the first filter cloth 3 moves, the first exchange product formed in the first cross-linked molecular sieve filter cake forming zone 7 enters the first ion exchange zone 11. A first phosphate solution with a temperature of 20-100℃, preferably 30-90℃, is added from the first container 9 through the third pipeline 10. Under vacuum, the first phosphate solution undergoes a second ion exchange treatment while passing through the first cross-linked filter cake, resulting in a second cross-linked filter cake.

[0091] IV. Washing

[0092] The washing method can employ methods known to those skilled in the art. The ion exchange filter cake obtained in the first ion exchange zone 11 enters the first water washing zone 14. Deionized water is added from the second container 12 through the fourth pipeline 13. The weight ratio of deionized water to the ion exchange filter cake is generally 1-15, preferably 2-10, and the temperature of the deionized water is 20-100℃, preferably 30-90℃. Under vacuum, the deionized water permeates through the ion exchange filter cake, washing away residual ions (especially anions) in the ion exchange filter cake to obtain the second exchange product. After drying and calcination, a calcined molecular sieve is obtained.

[0093] V. Preparation of Molecular Sieve Filter Cake

[0094] A 1-baked molecular sieve slurry at 10-100℃ (preferably 50-90℃) is continuously loaded from the third pulping tank 15 onto the second filter cloth 17 of the second belt filter via the fifth pipeline 16. The second filter cloth moves continuously into the 1-baked molecular sieve cake forming zone 18. A second liquid receiver 22 is located below the second filter cloth 17. The liquid receiver 22 is evacuated, and under vacuum, the liquid in the slurry on the second filter cloth 17 passes through the second filter cloth 17 and enters the second liquid receiver 22. Simultaneously, a 1-baked molecular sieve filter cake is formed on the second filter cloth 17. The loading rate of the 1-baked molecular sieve slurry should ensure that the thickness of the formed 1-baked molecular sieve filter cake is 0.5-2.0 cm, preferably 0.8-1.5 cm. The vacuum level in the second liquid receiver 22 ensures that the filter cake surface is free of cracks. The vacuum level in the second liquid receiver 22 includes, but is not limited to, 0.02-0.08 MPa, preferably 0.03-0.08 MPa.

[0095] VI. Third Ion Exchange Treatment

[0096] As the second filter cloth 17 moves, the single-stage molecular sieve filter cake formed in the double-stage filter cake forming zone 18 enters the second ion exchange zone 21. A second phosphate solution with a temperature of 20-100℃, preferably 30-90℃, is added through the third container 19 and the sixth pipeline 20. Under vacuum, the second phosphate solution undergoes a third ion exchange treatment while passing through the single-stage molecular sieve filter cake, resulting in a triple-stage filter cake.

[0097] VII. Preparation of Y-type molecular sieves containing phosphorus and rare earth elements

[0098] The washing method can employ methods known to those skilled in the art. Deionized water is added from the fourth container 23 through the seventh pipeline 24 to the triple-cross filter cake obtained in the second ion exchange zone 21. The weight ratio of deionized water to the triple-cross filter cake is generally 1-15, preferably 2-10, and the temperature of the deionized water is 20-100℃, preferably 30-90℃. Under vacuum, the deionized water permeates through the triple-cross filter cake, washing away residual ions to obtain the third exchange product. After washing and filtration, a phosphorus- and rare-earth-containing Y-type molecular sieve is obtained. This phosphorus- and rare-earth-containing Y-type molecular sieve is then subjected to microsphere treatment.

[0099] A third aspect of the present invention provides a method for heavy oil catalytic cracking, wherein a catalyst is brought into contact with feedstock oil under catalytic cracking conditions to react, and the catalyst is a core-shell structured catalyst as described in the first aspect.

[0100] Since the core-shell structure catalyst used in this invention is used for catalytic cracking, it can significantly improve the conversion rate of heavy oil.

[0101] The present invention will be further described below through specific embodiments and comparative examples. Unless otherwise specified, all percentages (%) refer to mass percentages. Unless otherwise specified, the rare earth metal content in the filtrate in the following embodiments and comparative examples refers to the content of rare earth metals in the filtrate as oxides; the amount of rare earth metals added refers to the amount as rare earth oxides.

[0102] The reagents and materials used in the following examples and comparative examples were sourced from the following sources:

[0103] 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%.

[0104] Lanthanum-rich rare earth chloride: an industrial product produced by Lanzhou Petrochemical Company, containing 290g / L of rare earth oxides, of which lanthanum oxide accounts for 83%, cerium dioxide accounts for 15%, and other rare earths account for 2%.

[0105] Lanthanum chloride, cerium chloride, yttrium chloride, potassium carbonate, potassium hydroxide, fulvic acid, brown humic acid, black humic acid, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and isooctanoates: yttrium isooctanoate, cerium isooctanoate, and antimony isooctanoate were all of analytical grade.

[0106] Kaolin, halloysite, montmorillonite, silica sol, boehmite, and aluminosilicate all come from Lanzhou Petrochemical Company.

[0107] Example 1

[0108] I. Preparation of Y-type molecular sieves containing phosphorus and rare earth elements

[0109] 1) Mix the first 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 obtain a molecular sieve slurry with a first NaY molecular sieve content of 180 g / L; heat the obtained molecular sieve slurry to 80°C, pour it into a Buchner funnel, and simultaneously evacuate the filter flask to 0.07 MPa to form a NaY molecular sieve filter cake with a thickness of 10 mm on the filter cloth;

[0110] 2) Mix the second NaY molecular sieve, phosphorus-containing filtrate B (obtained in Comparative Example 1), and lanthanum chloride into a slurry. The mass ratio of lanthanum oxide to the second NaY molecular sieve is 0.05:1, and the mass ratio of phosphorus-containing filtrate B to the second NaY molecular sieve is 9:1. Prepare a molecular sieve slurry with a second NaY molecular sieve content of 120 g / L. Heat the obtained molecular sieve slurry to 70°C and stir for 1 hour. Pour it onto the NaY molecular sieve filter cake in the Buchner funnel in step 1). At the same time, evacuate the filter flask to 0.07 MPa to form a 10 mm thick cross-linked filter cake (first exchange product) on the filter cloth.

[0111] 3) When there is no liquid on the surface of the first exchange filter cake, immediately add ammonium phosphate solution at 90℃. The addition speed should be such that the surface of the filter cake does not crack. The amount of ammonium phosphate solution should be such that the weight ratio of phosphorus to the second NaY molecular sieve is 0.2:1. When there is no liquid on the surface of the filter cake, immediately add deionized water at 80℃ to wash the filter cake. The weight ratio of deionized water to molecular sieve is 5:1. The product filter cake (second exchange product) and filtrate E are obtained. Then the product filter cake is removed and dried at 120℃ and calcined at 600℃ for 2 hours to obtain the first calcined molecular sieve.

[0112] 4) Mix the 1-baked molecular sieve with water to make a 1-baked molecular sieve slurry with a 110 g / L baked molecular sieve content. 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.

[0113] 5) When there is no liquid on the surface of the filter cake from 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 be such that the surface of the filter cake does not crack. The amount of ammonium phosphate solution should be such that the weight ratio of phosphorus to molecular sieve is 0.1:1. When there is no liquid on the surface of the filter cake, 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 5:1. Then, filter cake molecular sieve sample (Y-type molecular sieve containing phosphorus and rare earth metals) S1 and filtrate F are obtained. The sodium oxide content of sample S1 is 0.9%, and the phosphorus content and rare earth content of filtrate E are 1.5 ppm and 6 ppm, respectively.

[0114] II. Preparation of Y-type molecular sieve microspheres containing phosphorus and rare earth metals

[0115] 100g of water, 35g (dry basis) of molecular sieve sample S1, 55g of kaolin (dry basis) and 10g of aluminum sol (dry basis) were added to a reaction vessel and stirred for 60 minutes. The mixture was then spray-dried at 150℃ to form a microsphere, and then calcined at 400℃ for 30 minutes to obtain Y-type molecular sieve microspheres containing phosphorus and rare earth metals.

[0116] III. Preparation of Core-Shell Structured Catalysts

[0117] Y-type molecular sieve microspheres containing phosphorus and rare earth metals were impregnated with a 3 g / L yttrium isooctanoate solution for 60 min and dried at 90 °C for 120 min. The content of yttrium isooctanoate was 0.015 wt% based on the total mass of the catalyst, thus obtaining catalyst L1.

[0118] Example 2

[0119] The preparation method is basically the same as that in Example 1, except for the raw materials, the proportion of raw materials, and the preparation parameters. The specific preparation method is as follows:

[0120] I. Preparation of Y-type molecular sieves containing phosphorus and rare earth elements

[0121] 1) Mix and slurry the first NaY molecular sieve, potassium hydroxide, potassium carbonate, and humic acid, wherein the dry weight ratio of potassium hydroxide:potassium carbonate:humic acid:NaY molecular sieve is 0.005:0.012:0.001:1, to obtain a molecular sieve slurry with a first NaY molecular sieve slurry content of 300 g / L; the molecular sieve slurry temperature is 15℃, and it is poured into a Buchner funnel, while the filter flask is evacuated to 0.08 MPa, forming a NaY molecular sieve filter cake with a thickness of 5 mm on the filter cloth;

[0122] 2) Mix and slurry the second NaY molecular sieve, filtrate F, and cerium chloride. The mass ratio of cerium chloride to the second NaY molecular sieve is 0.1:1, and the mass of filtrate F is twice that of the second NaY molecular sieve. Heat the resulting molecular sieve slurry to 50°C and stir for 2 hours. Pour the slurry onto the NaY molecular sieve filter cake in the Buchner funnel in step 1). At the same time, evacuate the filter flask to 0.08 MPa to form a 15 mm thick cross-linked filter cake (first exchange product) on the filter cloth.

[0123] 3) When there is no liquid on the surface of the first exchange filter cake, immediately add ammonium phosphate solution at 100℃. The addition speed should be such that the filter cake surface does not crack. The amount of ammonium phosphate solution should be such that the weight ratio of phosphorus to the second NaY molecular sieve is 0.05:1. When there is no liquid on the surface of the filter cake, immediately add deionized water at 100℃ to wash the filter cake. The weight ratio of deionized water to molecular sieve is 1:1. The product filter cake (second exchange product) and filtrate G are obtained. Then, the product filter cake is removed and dried at 200℃ and calcined at 500℃ for 3 hours to obtain a first calcined molecular sieve.

[0124] 4) Mix the 1-baked molecular sieve with water to make a 1-baked molecular sieve slurry with a 1-baked molecular sieve content of 300 g / L. Heat the obtained molecular sieve slurry to 100°C and pour it into a Buchner funnel. At the same time, evacuate the filter flask to 0.02 MPa to form a filter cake with a thickness of 5 mm on the filter cloth.

[0125] 5) When there is no liquid on the surface of the filter cake from step 4), immediately add a diammonium hydrogen phosphate solution with a phosphorus content of 100 g / L and a temperature of 100°C. The addition speed should be such that the surface of the filter cake does not crack. The weight ratio of phosphorus to molecular sieve is 0.06:1. When there is no liquid on the surface of the filter cake, immediately add deionized water at a temperature of 20°C to wash the filter cake. The weight ratio of deionized water to molecular sieve is 15:1. Molecular sieve sample S2 and filtrate H are obtained. The sodium oxide content of sample S2 is 1.1%, and the phosphorus content and rare earth content of filtrate G are 1 ppm and 3 ppm, respectively.

[0126] II. Preparation of Y-type molecular sieve microspheres containing phosphorus and rare earth metals

[0127] 150g of water, 20g (dry basis) of S2 molecular sieve, 65g of halloysite (dry basis) and 15g of silica sol (dry basis) were added to a reaction vessel and stirred for 15 minutes. The mixture was then spray-dried at 200°C to form a microsphere, and then calcined at 500°C for 15 minutes to obtain Y-type molecular sieve microspheres containing phosphorus and rare earth metals.

[0128] III. Preparation of Core-Shell Structured Catalysts

[0129] Y-type molecular sieve microspheres containing phosphorus and rare earth metals were impregnated with a cerium isooctanoate solution with a concentration of 2.1 g / L for 15 min and dried at 85 °C for 90 min. The cerium isooctanoate content was 0.055 wt% based on the total mass of the catalyst, thus obtaining catalyst L2.

[0130] Example 3

[0131] The preparation method is basically the same as that in Example 1, except for the raw materials, the proportion of raw materials, and the preparation parameters. The specific preparation method is as follows:

[0132] I. Preparation of Y-type molecular sieves containing phosphorus and rare earth elements

[0133] 1) Mix and slurry the first NaY molecular sieve, potassium hydroxide, potassium carbonate, and humic acid, wherein the dry weight ratio of potassium hydroxide:potassium carbonate:humic acid:NaY molecular sieve is 0.008:0.01:0.02:1, to obtain a molecular sieve slurry with a first NaY molecular sieve slurry content of 100 g / L; the molecular sieve slurry temperature is 100℃, and it is poured into a Buchner funnel, while the filter flask is evacuated to 0.02 MPa, forming a NaY molecular sieve filter cake with a thickness of 15 mm on the filter cloth;

[0134] 2) Mix and slurry the second NaY molecular sieve, filtrate H, and yttrium chloride. The mass ratio of yttrium chloride to the second NaY molecular sieve is 0.01:1, and the mass of filtrate H is 10 times that of the second NaY molecular sieve. Heat the resulting molecular sieve slurry to 100°C and stir for 0.5 h. Pour the slurry onto the NaY molecular sieve filter cake in the Buchner funnel in step 1). At the same time, evacuate the filter flask to 0.02 MPa to form a 5 mm thick cross-linked filter cake (first exchange product) on the filter cloth.

[0135] 3) When there is no liquid on the surface of the first exchange filter cake, immediately add ammonium phosphate solution at 20°C. The addition speed should be such that the surface of the filter cake does not crack. The amount of ammonium phosphate solution should be such that the weight ratio of phosphorus to the second NaY molecular sieve is 0.005:1. When there is no liquid on the surface of the filter cake, immediately add deionized water at 20°C to wash the filter cake. The weight ratio of deionized water to molecular sieve is 15:1. The product filter cake (second exchange product) and filtrate I are obtained. Then the product filter cake is removed and dried at 20°C and calcined at 800°C for 1 hour to obtain a first calcined molecular sieve.

[0136] 4) Mix the 1-baked molecular sieve with water to make a 100 g / L 1-baked molecular sieve slurry. Heat the obtained molecular sieve slurry to 20°C and pour it into a Buchner funnel. At the same time, evacuate the filter flask to 0.08 MPa to form a filter cake with a thickness of 20 mm on the filter cloth.

[0137] 5) When there is no liquid on the surface of the filter cake from step 4), immediately add an ammonium dihydrogen phosphate solution with a phosphorus content of 15 g / L and a temperature of 20°C. The addition speed should be such that the surface of the filter cake does not crack. The weight ratio of phosphorus to molecular sieve is 0.15:1. When there is no liquid on the surface of the filter cake, immediately add deionized water at a temperature of 100°C to wash the filter cake. The weight ratio of deionized water to molecular sieve is 15:1. Molecular sieve sample S3 and filtrate J are obtained. Sample S3 has a sodium oxide content of 1.0%, and filtrate I has a phosphorus content of 0.8 ppm and a rare earth content of 4 ppm.

[0138] II. Preparation of Y-type molecular sieve microspheres containing phosphorus and rare earth metals

[0139] 200g of water, 65g (dry basis) of S3 molecular sieve, 18g of montmorillonite (dry basis) and 17g of boehmite (dry basis) were added to a reactor. 5g of hydrochloric acid was added and stirred for 90 minutes. The mixture was then spray-dried at 100°C to form the microspheres, and then calcined at 300°C for 60 minutes to obtain Y-type molecular sieve microspheres containing phosphorus and rare earth metals.

[0140] III. Preparation of Core-Shell Structured Catalysts

[0141] Y-type molecular sieve microspheres containing phosphorus and rare earth metals were impregnated with a 1.65 g / L antimony isooctanoate solution for 80 min and dried at 140 °C for 60 min. The antimony isooctanoate content was 0.9 wt% based on the total mass of the molecular sieve, thus obtaining catalyst L3.

[0142] Example 4

[0143] The preparation method is basically the same as that in Example 1, except for the raw materials, the proportion of raw materials, and the preparation parameters. The specific preparation method is as follows:

[0144] I. Preparation of Y-type molecular sieves containing phosphorus and rare earth elements

[0145] 1) A mixture of the first NaY molecular sieve, potassium hydroxide, potassium carbonate, humic acid, and fulvic acid is mixed and pulped, wherein the dry weight ratio of potassium hydroxide:potassium carbonate:mixture of humic acid and fulvic acid:NaY molecular sieve is 0.011:0.007:0.006:1, resulting in a molecular sieve slurry with a first NaY molecular sieve slurry content of 180 g / L; the molecular sieve slurry temperature is 75℃, and it is poured into a Buchner funnel, while the filter flask is evacuated to 0.04 MPa, forming a NaY molecular sieve filter cake with a thickness of 8 mm on the filter cloth;

[0146] 2) Mix and slurry the second NaY molecular sieve, filtrate J, and lanthanum chloride. The mass ratio of lanthanum chloride to molecular sieve is 0.06:1, and the mass of filtrate J is 5 times that of the second NaY molecular sieve. Then add lanthanum-rich rare earth chloride. The amount of rare earth salt added is calculated as rare earth oxides, and the weight ratio of rare earth oxides to the second NaY molecular sieve is 0.04:1. Heat the obtained molecular sieve slurry to 70°C and stir for 1.5 hours. Pour it onto the NaY molecular sieve filter cake in the Buchner funnel in step 1). At the same time, evacuate the filter flask to 0.04 MPa to form a 13 mm thick cross-linked filter cake (first exchange product) on the filter cloth.

[0147] 3) When there is no liquid on the surface of the first exchange filter cake, immediately add ammonium phosphate solution at 50°C. The addition speed should be such that the surface of the filter cake does not crack. The amount of ammonium phosphate solution should be such that the weight ratio of phosphorus to molecular sieve is 0.17:1. When there is no liquid on the surface of the filter cake, immediately add deionized water at 40°C to wash the filter cake. The weight ratio of deionized water to molecular sieve is 8:1. The product filter cake (second exchange product) and filtrate K are obtained. Then the product filter cake is removed and dried at 60°C and calcined at 600°C for 1.5 hours to obtain a first-calcined molecular sieve.

[0148] 4) Mix the 1-baked molecular sieve with water to make a 1-baked molecular sieve slurry with a 170 g / L baked molecular sieve content. Heat the obtained molecular sieve slurry to 60°C and pour it into a Buchner funnel. At the same time, evacuate the filter flask to 0.04 MPa to form a filter cake with a thickness of 18 mm on the filter cloth.

[0149] 5) When there is no liquid on the surface of the filter cake from step 4), immediately add an ammonium dihydrogen phosphate solution with a phosphorus content of 75 g / L and a temperature of 45°C. The addition speed should be such that the surface of the filter cake does not crack. The weight ratio of phosphorus to molecular sieve is 0.07:1. When there is no liquid on the surface of the filter cake, immediately add deionized water at a temperature of 60°C to wash the filter cake. The weight ratio of deionized water to molecular sieve is 9:1. After drying at 200°C, calcine at 500°C for 1 hour to obtain molecular sieve sample S4 and collected filtrate L. The sodium oxide content of sample S4 is 1.2%, and the phosphorus content and rare earth content of filtrate K are 3 ppm and 1 ppm, respectively.

[0150] II. Preparation of Y-type molecular sieve microspheres containing phosphorus and rare earth metals

[0151] 310g of water, 45g (dry basis) of S4 molecular sieve, 50g of kaolin (dry basis) and 5g of aluminum sol (dry basis) were added to a reaction vessel and stirred for 39 minutes. The mixture was then spray-dried at 130°C to form the microspheres, and then calcined at 430°C for 40 minutes to obtain Y-type molecular sieve microspheres containing phosphorus and rare earth metals.

[0152] III. Preparation of Core-Shell Structured Catalysts

[0153] Y-type molecular sieve microspheres containing phosphorus and rare earth metals were impregnated with a 2.65 g / L antimony isooctanoate solution for 65 min and dried at 100 °C for 2120 min. The antimony isooctanoate content was 0.075 wt% based on the total mass of the catalyst, thus obtaining catalyst L4.

[0154] Comparative Example 1

[0155] I. Preparation of phosphorus and rare earth metal-containing molecular sieves: A calcined molecular sieve sample was prepared according to the method disclosed in patent document CN1485136A, specifically including the following steps:

[0156] 1) Filter cake formation: 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. The filter cake in the Buchner funnel was then evacuated to 0.05 MPa. Under vacuum, a filter cake with a thickness of 1.2 cm was formed on the filter cloth of the Buchner funnel. The waste liquid in the filtration flask was then drained.

[0157] 2) Ion exchange: 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 at 65°C containing 50 g / L of lanthanum oxide. 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 0.05:1.

[0158] 3) Washing: 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.

[0159] 4) Absorb dry: Continue to evacuate until no liquid flows out of the funnel, and obtain the filtered cake and filtrate A after absorbing dry.

[0160] 5) Remove the filter cake and dry: Take the filter cloth out of the funnel and remove the filter cake from the filter cloth. Dry it at 140℃ to obtain a 1-baked molecular sieve. The sodium oxide content in the 1-baked molecular sieve was measured to be 4.6%, the rare earth content was 4.53%, and the rare earth content in filtrate A was 3208 ppm.

[0161] Molecular sieve samples were prepared according to the method disclosed in patent CN1416951A, specifically including the following steps:

[0162] 1) Mix the prepared molecular sieve, deionized water, and filtrate A to form a slurry containing 120 g / L of molecular sieve. The amount of salt (i.e., rare earth chloride and sodium chloride contained in the filtrate) is 1.1 wt% of the molecular sieve. Heat the resulting molecular sieve slurry to 90°C and pour it into a Buchner funnel. Simultaneously, evacuate the filter flask to 0.07 MPa to form a 10 mm thick filter cake on the filter cloth. When there is no liquid on the surface of the filter cake, immediately add phosphorus containing 50 g / L at a temperature of 90°C. An ammonium phosphate solution at ℃ was added at a rate that ensured no cracks formed on the surface of the filter cake. The amount of ammonium phosphate solution used was such that the weight ratio of phosphorus to molecular sieve was 0.1:1. When there was no liquid on the surface of the filter cake, deionized water at 90℃ was immediately added to wash the filter cake, with a weight ratio of deionized water to molecular sieve of 3:1. Then the filter cake and filtrate B were removed, and the filter cake was dried at 120℃ to obtain rare earth Y-type molecular sieve D1. The sodium oxide content in D1 was 1.0%, the phosphorus content in filtrate B was 125 ppm, and the rare earth content was 796 ppm.

[0163] II. Preparation of Y-type molecular sieve microspheres containing phosphorus and rare earth metals

[0164] Add 100g of water, 35g of D1 molecular sieve (on a dry basis), 55g of kaolin (on a dry basis) and 10g of aluminum sol (on a dry basis) to a reactor, stir for 60 minutes, spray mold at 150℃, and then calcine at 400℃ for 30 minutes to obtain Y-type molecular sieve microspheres containing phosphorus and rare earth metals.

[0165] III. Preparation of Core-Shell Structured Catalysts

[0166] Y-type molecular sieve microspheres containing phosphorus and rare earth metals were impregnated with a 3 g / L yttrium isooctanoate solution for 60 min and dried at 90 °C for 120 min to obtain molecular sieve G1. The content of isooctanoate was 0.015 wt% based on the total mass of the molecular sieve.

[0167] Comparative Example 2

[0168] I. Preparation of molecular sieves containing rare earth metals, referring to the method disclosed in patent document CN108097288A, specifically includes the following steps:

[0169] 1) Add 150g of dry NaY molecular sieve to 750g of deionized water at 70℃, and add 3.2g of lanthanum chloride while stirring. Stir at 70℃ for 60 minutes to exchange the ions.

[0170] 2) Add a 15% oxalic acid solution, continue stirring for 20 minutes, then wash and filter with 225g of deionized water at 70℃, discard the waste filtrate, and obtain the first filter cake.

[0171] 3) Add 525g of deionized water at 50℃ to the first filter cake in step 2), and add 18.75g of lanthanum chloride while stirring. Stir for 60 minutes at 50℃, then wash and filter with 225g of deionized water at 70℃ to obtain product filter cake A and recycled filtrate C.

[0172] 4) Add 150 g of dry NaY molecular sieve to 750 g of recycled filtrate C, stir at 70°C for 60 minutes, then add 15% oxalic acid solution, continue stirring for 20 minutes, then wash and filter with 225 g of 70°C deionized water, discard the waste filtrate to obtain the second filter cake; add 525 g of 50°C deionized water to the second filter cake, while stirring, add 17.13 g of lanthanum chloride, stir at 70°C for 60 minutes, then wash and filter with 225 g of 50°C deionized water to obtain product filter cake B and recycled filtrate D;

[0173] By calcining product filter cakes A and B in a muffle furnace at 580℃ for 3 hours, molecular sieve D2 containing rare earth metals can be obtained, with a sodium oxide content of 3.5%, a rare earth content of 23.5%, and a rare earth utilization rate of 97.9%.

[0174] II. Preparation of Y-type molecular sieve microspheres containing rare earth metals

[0175] Add 100g of water, 35g of D2 molecular sieve (on a dry basis), 55g of kaolin (on a dry basis) and 10g of aluminum sol (on a dry basis) to a reactor, stir for 60 minutes, spray mold at 150℃, and then calcine at 400℃ for 30 minutes to obtain Y-type molecular sieve microspheres containing rare earth metals.

[0176] III. Preparation of Core-Shell Structured Catalysts

[0177] Y-type molecular sieve microspheres containing rare earth metals were impregnated with a 3 g / L yttrium isooctanoate solution for 60 min and dried at 90 °C for 120 min. The content of yttrium isooctanoate was 0.015 wt% based on the total mass of the catalyst, thus obtaining molecular sieve G2.

[0178] Comparative Example 3

[0179] I. Preparation of Y-type molecular sieves containing phosphorus and rare earth metals, following the method disclosed in patent document CN101722021B, specifically including the following steps:

[0180] Dissolve 30g of potassium hydroxide in 1200g of distilled water, stir until homogeneous to prepare an alkaline solution, and then heat to 60℃. Add 200g of NaY molecular sieve (dry basis) to the above alkaline solution, stir at 60℃ for 10 hours, filter, wash thoroughly with deionized water until the pH of the filtrate is less than 10, and dry. Add 90g of the alkaline-treated product and 15.8mL of mixed rare earth solution (RE2O3 content 285g / L) to 450g of distilled water, stir until homogeneous, and then stir and exchange at 80℃ for 1 hour. The pH of the exchange slurry was adjusted to 3.5 using a 1 mol / L hydrochloric acid solution. After the exchange was completed, the slurry was filtered, and an ammonium phosphate solution at 90°C was added. The amount of ammonium phosphate solution was such that the weight ratio of phosphorus to molecular sieve was 0.20:1. The slurry was then thoroughly washed with water, and the filter cake was removed, dried at 120°C, and calcined at 600°C for 2 hours to obtain a calcined molecular sieve sample. The calcined molecular sieve sample contained 4.8% sodium oxide and 4.1% RE2O3. The rare earth utilization rate of the first exchange process was 82%, and the phosphorus content in the filtrate was 17893 ppm.

[0181] 50g of monocalcined molecular sieve sample was added together with ammonium phosphate solution to 180g of distilled water and stirred until homogeneous. The amount of ammonium phosphate solution was adjusted so that the weight ratio of phosphorus to molecular sieve was 0.1. The mixture was then stirred and exchanged at 80℃ for 3h. During the exchange process, the pH of the exchange slurry was adjusted to 4.2 using 1mol / L hydrochloric acid solution and maintained thereafter. After the exchange was completed, the mixture was filtered and thoroughly washed with water to obtain molecular sieve D3, which had a sodium oxide content of 2.1%, a Re2O3 content of 3.8%, and a phosphorus content of 5124ppm in the second crosslinking filtrate.

[0182] II. Preparation of Y-type molecular sieve microspheres containing phosphorus and rare earth metals

[0183] 100g of water, 35g (dry basis) of molecular sieve D3, 55g of kaolin (dry basis) and 10g of aluminum sol (dry basis) were added to a reaction vessel and stirred for 60 minutes. The mixture was then spray-molded at 150°C and calcined at 400°C for 30 minutes to obtain Y-type molecular sieve microspheres containing phosphorus and rare earth metals.

[0184] III. Preparation of Core-Shell Structured Catalysts

[0185] Y-type molecular sieve microspheres containing rare earth metals were impregnated with a 3 g / L yttrium isooctanoate solution for 60 min and dried at 90 °C for 120 min. The content of yttrium isooctanoate was 0.015 wt% based on the total mass of the catalyst, thus obtaining catalyst G3.

[0186] Comparative Example 4

[0187] The preparation method is basically the same as that in Example 1, except for the raw materials, the proportion of raw materials, and the preparation parameters. The specific preparation method is as follows:

[0188] I. Preparation of Y-type molecular sieves containing phosphorus and rare earth elements

[0189] 1) Mix and slurry the first NaY molecular sieve, potassium hydroxide, potassium carbonate, and humic acid, wherein the dry weight ratio of potassium hydroxide:potassium carbonate:humic acid:NaY molecular sieve is 0.005:0.012:0.001:1, to obtain a molecular sieve slurry with a first NaY molecular sieve slurry content of 300 g / L; the molecular sieve slurry temperature is 15℃, and it is poured into a Buchner funnel, while the filter flask is evacuated to 0.08 MPa, forming a NaY molecular sieve filter cake with a thickness of 5 mm on the filter cloth;

[0190] 2) Mix and slurry the second NaY molecular sieve, filtrate F, and cerium chloride. The mass ratio of cerium chloride to the second NaY molecular sieve is 0.1:1, and the mass of filtrate F is twice that of the second NaY molecular sieve. Heat the resulting molecular sieve slurry to 50°C and stir for 2 hours. Pour the slurry onto the NaY molecular sieve filter cake in the Buchner funnel in step 1). At the same time, evacuate the filter flask to 0.08 MPa to form a 15 mm thick cross-linked filter cake (first exchange product) on the filter cloth.

[0191] 3) When there is no liquid on the surface of the first exchange filter cake, immediately add ammonium phosphate solution at 100℃. The addition speed should be such that the filter cake surface does not crack. The amount of ammonium phosphate solution should be such that the weight ratio of phosphorus to the second NaY molecular sieve is 0.05:1. When there is no liquid on the surface of the filter cake, immediately add deionized water at 100℃ to wash the filter cake. The weight ratio of deionized water to molecular sieve is 1:1. The product filter cake (second exchange product) and filtrate G are obtained. Then, the product filter cake is removed and dried at 200℃ and calcined at 500℃ for 3 hours to obtain a first calcined molecular sieve.

[0192] 4) Mix the 1-baked molecular sieve with water to make a 1-baked molecular sieve slurry with a 1-baked molecular sieve content of 300 g / L. Heat the obtained molecular sieve slurry to 100°C and pour it into a Buchner funnel. At the same time, evacuate the filter flask to 0.02 MPa to form a filter cake with a thickness of 5 mm on the filter cloth.

[0193] 5) When there is no liquid on the surface of the filter cake from step 4), immediately add a diammonium hydrogen phosphate solution with a phosphorus content of 100 g / L and a temperature of 100°C. The addition speed should be such that the surface of the filter cake does not crack. The weight ratio of phosphorus to molecular sieve is 0.06:1. When there is no liquid on the surface of the filter cake, immediately add deionized water at a temperature of 20°C to wash the filter cake. The weight ratio of deionized water to molecular sieve is 15:1. Molecular sieve sample S2 and filtrate H are obtained. The sodium oxide content of sample S2 is 1.1%, and the phosphorus content and rare earth content of filtrate G are 1 ppm and 3 ppm, respectively.

[0194] II. Preparation of Y-type molecular sieve microspheres containing phosphorus and rare earth metals

[0195] 150g of water, 20g (dry basis) of S2 molecular sieve, 65g of halloysite (dry basis) and 15g of silica sol (dry basis) were added to a reactor and stirred for 15 minutes. The mixture was then spray-dried at 200°C to form the microspheres, and then calcined at 500°C for 15 minutes to obtain Y-type molecular sieve microspheres G4 containing phosphorus and rare earth metals.

[0196] Test case

[0197] Catalytic cracking selectivity evaluation: The catalytic cracking selectivity evaluation was conducted in a small-scale fixed fluidized bed (FFB) test unit (XGL-2, Luoyang). The molecular sieve catalyst was pretreated at 800℃ and 100% steam for 10 h. The feedstock was Lanzhou Petrochemical catalytic feedstock, and its specific properties are shown in Table 1. The reaction temperature was 500–535℃, and the space velocity was 12–15 h⁻¹. -1 The ratio of agent to oil is 5.

[0198] Specific analysis methods:

[0199] 1) The content of sodium oxide, phosphorus, and rare earth oxide in the molecular sieve was analyzed by X-ray fluorescence spectrometry.

[0200] 2) Phosphorus content and rare earth metal content: detected using an ICP (Inductively Coupled Plasma Emission Spectrometer);

[0201] 3) Calculation method for rare earth utilization rate:

[0202]

[0203] In the formula, C i - The concentration of rare earth elements added to the rare earth-containing solution (calculated as rare earth oxides), g / mL;

[0204] V - The volume of rare earth-containing solution added, in mL;

[0205] R i - The mass of solid rare earth added (based on rare earth oxides), g;

[0206] The rare earth concentration (calculated as rare earth oxide) of the filtrate collected after Co-filter cake filtration, g / mL;

[0207] Vo - The volume of filtrate collected after filter cake filtration, in mL.

[0208] 4) Formula for calculating the focus factor: Focus factor (CF) = Y coke ×(100-X) / X, where CF is the fogging factor, and Y is the focal length factor. coke Let X be the coke yield, and X be the conversion rate.

[0209] Table 1

[0210]

[0211] Table 2

[0212]

[0213] In the table, coke = carbon infrared meter * 100 / inlet oil mass; conversion rate = dry gas + liquefied petroleum gas + C5 gasoline + coke; total liquid recovery = light liquid recovery + liquefied petroleum gas; light liquid recovery = C5 gasoline + diesel.

[0214] As shown in Table 2, the core-shell structure catalyst provided by this invention results in a smaller coking factor and a higher heavy oil conversion rate during heavy oil catalytic cracking, indicating that the core-shell structure catalyst provided by this invention has excellent coking performance and heavy oil conversion capability.

[0215] The preferred embodiments and experimental verifications of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A core-shell structured catalyst, characterized in that, Includes a core and a shell covering at least a portion of the surface of the core; The core comprises a Y-type molecular sieve containing phosphorus and rare earth metals, and the shell comprises isooctanoate. In the core-shell structured catalyst, the mass content of the isooctanoate is 0.01~1%; The isooctanoate includes at least one of yttrium isooctanoate, cerium isooctanoate, and antimony isooctanoate; The core-shell structured catalyst is prepared by a method including the following process: coating phosphorus-containing and rare earth metal-containing Y-type molecular sieve microspheres with isooctanoate to obtain the core-shell structured catalyst.

2. The core-shell structured catalyst according to claim 1, characterized in that, The phosphorus- and rare earth metal-containing Y-type molecular sieve microspheres are prepared by a method comprising the following steps: A first NaY molecular sieve, an alkali metal hydroxide, a carbonate, humic acid, and water are mixed and pretreated to obtain a pretreated molecular sieve. The alkali metal hydroxide includes at least one of sodium hydroxide and potassium hydroxide. The humic acid includes at least one of fulvic acid, brown humic acid, and black humic acid. The mass ratio of the alkali metal hydroxide, carbonate, humic acid, and first NaY molecular sieve is (0.005~0.012):(0.005~0.012):(0.001~0.05):

1. The pretreated molecular sieve is subjected to a first ion exchange treatment in a slurry containing a second NaY molecular sieve, a phosphorus-containing filtrate, and a rare earth metal salt to obtain a first exchange product; the first exchange product is subjected to a second ion exchange treatment in a phosphate solution to obtain a second exchange product. The phosphate in the phosphate solution is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, and diammonium dihydrogen phosphate. After the second exchange product is subjected to a first drying and a first calcination, a Y-type molecular sieve containing phosphorus and rare earth metals is obtained. The phosphorus- and rare earth metal-containing Y-type molecular sieve, clay, binder, and water are mixed, and then spray-dried and subjected to a second calcination treatment to obtain phosphorus- and rare earth metal-containing Y-type molecular sieve microspheres.

3. A method for preparing a core-shell structured catalyst as described in claim 1 or 2, characterized in that, Includes the following steps: A core-shell structured catalyst was obtained by coating phosphorus- and rare earth metal-containing Y-type molecular sieve microspheres with isooctanoate.

4. The preparation method according to claim 3, characterized in that, Also includes: The first NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid and water were mixed and pretreated to obtain a pretreated molecular sieve. The alkali metal hydroxide includes at least one of sodium hydroxide and potassium hydroxide; the humic acid includes at least one of fulvic acid, brown humic acid, and black humic acid; the mass ratio of the alkali metal hydroxide, carbonate, humic acid, and the first NaY molecular sieve is (0.005~0.012):(0.005~0.012):(0.001~0.05):1; The pretreated molecular sieve is subjected to a first ion exchange treatment in a slurry containing a second NaY molecular sieve, a phosphorus-containing filtrate, and rare earth metal salts to obtain a first exchange product. The first exchange product is subjected to a second ion exchange treatment in a phosphate solution to obtain a second exchange product and a first filtrate; the phosphate in the phosphate solution is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate. After subjecting the second exchange product to a first drying and a first calcination treatment, a Y-type molecular sieve containing phosphorus and rare earth metals is obtained. The phosphorus- and rare earth metal-containing Y-type molecular sieve, clay, binder, and water are mixed, and then spray-dried and subjected to a second calcination treatment to obtain phosphorus- and rare earth metal-containing Y-type molecular sieve microspheres.

5. The preparation method according to claim 4, characterized in that, The carbonate includes at least one of potassium carbonate and sodium carbonate; and / or, The rare earth metal salt is selected from at least one of lanthanum salt, cerium salt, praseodymium salt, neodymium salt, and yttrium salt; and / or, The clay is selected from at least one of kaolin, halloysite, and montmorillonite; and / or, The binder is selected from at least one of aluminum sol, silica sol, and boehmite.

6. The preparation method according to claim 4, characterized in that, The rare earth metal salt, calculated as rare earth metal oxide, has a mass ratio of (0.01~0.1):1 to the second NaY molecular sieve; and / or, The phosphate solution, calculated as elemental phosphorus, has a mass ratio of (0.005~0.15):1 with the second NaY molecular sieve; and / or, The conditions for the first ion exchange treatment are: temperature 50–100 °C, time 0.5–2 h; and / or, The temperature for the first drying step is 20~200℃, and the temperature for spray drying is 100~200℃; and / or, The conditions for the first roasting are: temperature 500~800℃, time 1~3h; and / or, The conditions for the second roasting are: temperature 300~500℃, time 15~60min.

7. A method for catalytic cracking of heavy oil, characterized in that, The catalyst is brought into contact with the feedstock oil under catalytic cracking conditions to react, wherein the catalyst is the core-shell structured catalyst as described in claim 1 or 2.

Images