A modified y-type molecular sieve catalyst, a preparation method and application thereof

Abstract

The application provides a modified Y-type molecular sieve catalyst and a preparation method and application thereof, and the preparation method comprises the following steps: mixing NaY molecular sieve, alkali metal hydroxide, alkali metal carbonate, humic acid and water to obtain pretreated molecular sieve; performing first ion exchange treatment on the pretreated molecular sieve in a solution containing phosphorus-containing filtrate and rare earth metal salt to obtain first exchange product and first filtrate; performing second ion exchange treatment on the first exchange product in a phosphate solution to obtain second exchange product and second filtrate; performing drying and calcination on the second exchange product to obtain Y-type molecular sieve containing phosphorus and rare earth metal; and mixing the Y-type molecular sieve containing phosphorus and rare earth metal, clay, binder and water, and performing drying and calcination treatment to obtain the modified Y-type molecular sieve catalyst. The preparation method can avoid the loss of phosphorus and rare earth metal, and the modified Y-type molecular sieve catalyst prepared by the method has strong heavy oil conversion capacity.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a modified Y-type molecular sieve catalyst, its preparation method, and its application. Background Technology

[0002] Y-type molecular sieves are aluminosilicates with a unique crystalline structure, exhibiting advantages such as high cracking activity and good selectivity. They are mainly used in refining processes such as catalytic cracking, hydrocracking, and isomerization of heavy oil. The catalytic performance of molecular sieves is one of the important factors affecting the catalytic cracking process.

[0003] Currently, modifying Y-type molecular sieves with rare earth metals and phosphorus is the main method to improve their catalytic performance. Most modified molecular sieves are synthesized using hydrothermal synthesis. However, due to the high pH value of the Y-type molecular sieve synthesis system, direct hydrothermal synthesis would cause strong hydrolysis of the metal atoms, and it is also difficult to introduce rare earth metals and phosphorus into the Y-type molecular sieve using this method.

[0004] Currently, liquid-phase ion exchange or impregnation methods are commonly used to modify Y-type molecular sieves with rare earth metals and phosphorus. For example, patent document CN103506153B discloses a catalytic cracking catalyst for reducing coke yield and producing gasoline, using NaY molecular sieves as raw material and adding phosphorus-containing and rare earth-containing material exchange solutions for exchange. Patent document CN101537366B discloses a modified molecular sieve that can improve coking performance, in which NaY molecular sieves are treated with phosphorus-containing ammonium solution for exchange, calcined under steam conditions, and then treated with Re-containing... 3+ Modified molecular sieves are obtained by calcining after ammonium solution exchange treatment and followed by hydrothermal treatment. Patent document CN102019195B discloses a catalytic cracking catalyst containing modified Y-type molecular sieves, which involves an exchange reaction between the Y-type molecular sieve and a rare earth solution, followed by the introduction of phosphorus precursors into the exchange slurry. After filtration and washing, the filter cake is calcined under steam. However, in the above method, the rare earth metal and phosphorus modification of the molecular sieve generally requires filtration followed by calcination. Some rare earth metals and phosphorus enter the filtrate and are lost, resulting in incomplete exchange of rare earth metals and phosphorus onto the molecular sieve. This leads to low metal utilization and phosphorus loss, thus affecting the catalytic performance of the Y-type molecular sieve.

[0005] Therefore, how to further improve the catalytic performance of Y-type molecular sieve catalysts is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] This invention provides a method for preparing a modified Y-type molecular sieve catalyst, which can avoid the loss of phosphorus and rare earth metals, and ensure that almost all rare earth metals and phosphorus are exchanged onto the Y-type molecular sieve, thereby obtaining a modified Y-type molecular sieve with strong heavy oil conversion ability.

[0007] This invention also provides a modified Y-type molecular sieve catalyst, prepared by the above method, which exhibits excellent performance in heavy oil conversion.

[0008] The present invention also provides a method for catalytic cracking of heavy oil, which can significantly improve the conversion rate of heavy oil by using the above-mentioned modified Y-type molecular sieve as a catalyst.

[0009] In a first aspect, the present invention provides a method for preparing a modified Y-type molecular sieve catalyst, comprising the following steps:

[0010] NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid and water are mixed and pretreated to obtain pretreated molecular sieve;

[0011] The pretreated molecular sieve is subjected to a first ion exchange treatment in a solution containing phosphorus-containing filtrate and rare earth metal salts. After filtration, a first exchange product and a first filtrate are obtained.

[0012] The first exchange product is subjected to a second ion exchange treatment in a phosphate solution, and after filtration, a second exchange product and a second filtrate are obtained.

[0013] After drying and calcining the second exchange product, a Y-type molecular sieve containing phosphorus and rare earth metals is obtained.

[0014] A modified Y-type molecular sieve catalyst is obtained by mixing phosphorus- and rare earth metal-containing Y-type molecular sieve, clay, binder, and water, followed by drying and calcination. The modified Y-type molecular sieve catalyst comprises the following components by mass: 25-70 wt% phosphorus- and rare earth metal-containing Y-type molecular sieve, 20-60 wt% clay, and 3-20 wt% binder.

[0015] In the preparation method described above, the first filtrate and / or the second filtrate are returned for a first ion exchange treatment.

[0016] In the preparation method described above, the first NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid and water are mixed and pretreated to obtain a pretreated molecular sieve.

[0017] The second NaY molecular sieve, phosphorus-containing filtrate, and rare earth metal salt are mixed and slurried to form the first exchange liquid; the pretreated molecular sieve undergoes the first ion exchange reaction in the first exchange liquid.

[0018] The preparation method described above further includes the following steps:

[0019] The first exchange product is subjected to a second ion exchange treatment in a first phosphate solution, and after filtration, a second exchange product and a third filtrate are obtained.

[0020] After drying and calcining the second exchange product, a calcined molecular sieve is obtained.

[0021] A molybdenum sieve is mixed with water and pulped to form a molybdenum sieve filter cake; the molybdenum sieve filter cake is subjected to a third ion exchange treatment in a second phosphate solution, and after filtration, a third exchange product and a fourth filtrate are obtained.

[0022] After washing and filtering the third exchange product, a Y-type molecular sieve containing phosphorus and rare earth elements was obtained.

[0023] In the preparation method described above, the third filtrate and / or the fourth filtrate are returned for a first ion exchange treatment.

[0024] The preparation method described above, wherein the humic acid includes at least one of fulvic acid, brown humic acid, and black humic acid; and / or,

[0025] The alkali metal hydroxide includes at least one of sodium hydroxide and potassium hydroxide; and / or,

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

[0027] The phosphate in the phosphate solution is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, and diammonium dihydrogen phosphate.

[0028] In the preparation method described above, the first phosphate solution and the second phosphate solution are calculated based on phosphorus element, the mass ratio of the first phosphate solution to the second NaY molecular sieve is (0.005~0.05):1, and the mass ratio of the second phosphate solution to the first NaY molecular sieve is (0.02-0.15):1.

[0029] In the preparation method described above, 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; and / or,

[0030] The mass ratio of the phosphorus-containing filtrate to the second NaY molecular sieve is (2-10):1; and / or,

[0031] 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,

[0032] The conditions for the first and second ion exchange treatments are each independently selected from: temperature 50–100°C, time 0.5–2 h; and / or,

[0033] The pretreatment temperature is 10-100℃, the drying temperature is 20-200℃, and the calcination conditions are 500-800℃ for 1-3 hours.

[0034] In a second aspect, the present invention provides a modified Y-type molecular sieve catalyst, which is prepared by the aforementioned preparation method.

[0035] A third aspect of the present invention provides a method for catalytic cracking of heavy oil, wherein, under catalytic cracking conditions, feedstock oil is brought into contact with a catalyst to react; wherein the catalyst is a modified Y-type molecular sieve catalyst as described above.

[0036] The implementation of this invention has at least the following beneficial effects:

[0037] The method for preparing the modified Y-type molecular sieve catalyst provided by this invention involves pretreatment in which humic acid combines with alkali metals to form sodium humate or potassium humate. During subsequent ion exchange treatment, sodium humate and potassium humate can synthesize organic rare earth complexes with rare earth metal ions 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 fixation effect, ensuring that rare earth metals and phosphorus are almost entirely exchanged onto the Y-type molecular sieve during the ion exchange treatment, which is beneficial for obtaining Y-type molecular sieves containing phosphorus and rare earth metals and improving the catalytic performance of the molecular sieve.

[0038] The modified Y-type molecular sieve catalyst provided by this invention exhibits excellent performance in heavy oil conversion due to being prepared by the above-mentioned method.

[0039] The heavy oil catalytic cracking method also provided by this invention can significantly improve the heavy oil conversion rate by using the above-mentioned modified Y-type molecular sieve catalyst as the catalyst. Attached Figure Description

[0040] Figure 1 This is a device diagram of a first belt filter according to an embodiment of the present invention;

[0041] Figure 2 This is a diagram of a second belt filter according to an embodiment of the present invention.

[0042] Explanation of reference numerals in the attached figures:

[0043] 3-First filter cloth; 4-NaY molecular sieve filter cake forming zone; 7-One-cross molecular sieve filter cake forming zone;

[0044] 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;

[0045] 8 - First liquid receiver; 22 - Second liquid receiver;

[0046] 1-First pulping tank; 5-Second pulping tank; 15-Third pulping tank;

[0047] 2 - First pipeline; 6 - Second pipeline; 10 - Third pipeline; 13 - Fourth pipeline; 16 - Fifth pipeline; 20 - Sixth pipeline; 24 - Seventh pipeline; 26 - Eighth pipeline;

[0048] 9 - First container; 12 - Second container; 19 - Third container; 23 - Fourth container. Detailed Implementation

[0049] 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.

[0050] In a first aspect, the present invention provides a method for preparing a modified Y-type molecular sieve catalyst, comprising the following steps: mixing NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid and water, and pretreating to obtain a pretreated molecular sieve; subjecting the pretreated molecular sieve to a first ion exchange treatment in a solution containing phosphorus-containing filtrate and rare earth metal salt, and after filtration, obtaining a first exchange product and a first filtrate; subjecting the first exchange product to a second ion exchange treatment in a phosphate solution, and after filtration, obtaining a second exchange product and a second filtrate; drying and calcining the second exchange product to obtain a phosphorus- and rare earth metal-containing Y-type molecular sieve; mixing the phosphorus- and rare earth metal-containing Y-type molecular sieve, clay, binder and water, and after drying and calcining, obtaining a modified Y-type molecular sieve catalyst, wherein the modified Y-type molecular sieve catalyst comprises the following components by mass percentage: 25-70 wt% phosphorus- and rare earth metal-containing Y-type molecular sieve, 20-60 wt% clay, and 3-20 wt% binder.

[0051] According to the technical solution provided by the present invention, by controlling the order of addition of each component, it is beneficial to obtain a modified Y-type molecular sieve catalyst. This molecular sieve catalyst has the advantages of high catalytic activity and strong heavy oil conversion ability. Applying this molecular sieve catalyst to the catalytic cracking of heavy oil can improve the heavy oil conversion rate. Based on this phenomenon, the inventors analyzed it and believe that it may be due to the following: Firstly, during the pretreatment process, alkali metal hydroxides and carbonates can remove amorphous silica and aluminum from the surface of the NaY molecular sieve while ensuring the integrity of the NaY molecular sieve crystals, which is beneficial for subsequent ion exchange treatment. Secondly, in the alkaline system formed by mixing NaY molecular sieve, alkali metal hydroxides, carbonates, humic acid, and water, humic acid combines with alkali metals to form sodium humate or potassium humate. During subsequent ion exchange treatment, sodium humate and potassium humate can combine with rare earth metal ions in rare earth metal salts through adsorption, exchange, and complexation to synthesize organic rare earth complexes, thereby limiting the migration of rare earth metals and reducing their loss. In addition, humic acid also has a phosphorus-fixing effect, making it difficult for phosphorus to be lost. This allows almost all rare earth metals and phosphorus to be exchanged onto the Y-type molecular sieve, which is beneficial for obtaining modified Y-type molecular sieve catalysts and improving the heavy oil conversion capacity of molecular sieve catalysts.

[0052] 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, 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 known as NaY molecular sieve filter cake) is obtained, and the filtrate is collected.

[0053] 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.

[0054] When the first exchange liquid is a solution containing phosphorus-containing filtrate and rare earth metal salts, in one embodiment, the pretreated molecular sieve is placed on a belt filter, so that the solution containing phosphorus-containing filtrate and rare earth metal salts (also referred to as the first exchange liquid) passes through the pretreated molecular sieve from one side and undergoes a first ion exchange reaction with the pretreated molecular sieve to obtain a filter cake. Then, sufficient washing water is sprinkled on it for washing, and finally the first exchange product and the second filtrate are obtained.

[0055] 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; and the pretreated molecular sieve undergoes a first ion exchange reaction in the first exchange solution.

[0056] 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. The rare earth metal salts 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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 washed and filtered to obtain a phosphorus- and rare earth-containing Y-type molecular sieve. The above process is beneficial for improving the phosphorus loading and utilization rate.

[0061] Furthermore, the third and / or fourth filtrates can be reused 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.

[0062] 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.

[0063] 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, binder, clay and water are mixed, and then dried and calcined to obtain a modified Y-type molecular sieve catalyst.

[0064] Furthermore, the third exchange product can be washed and filtered to obtain a Y-type molecular sieve containing phosphorus and rare earth metals. Then, the phosphorus and rare earth metal-containing Y-type molecular sieve, binder, clay, and water are mixed, and subsequently 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% phosphorus and rare earth metal-containing Y-type molecular sieve, 20-60 wt% clay, and 3-20 wt% binder. The above method simplifies the preparation process.

[0065] This invention does not limit the mixing method of phosphorus- and rare earth metal-containing Y-type molecular sieves, clay, binder, and water, as long as the modified Y-type molecular sieve catalyst obtained after drying and calcination meets the above-mentioned mass proportions. The clay can be selected from at least one of kaolin, halloysite, and montmorillonite; the binder can be selected from at least one of alumina sol, silica sol, and boehmite. This invention does not limit the drying method; it can be a conventional drying method in the art, such as spray drying. In the above method, the spray drying temperature can be 100–200°C, and the calcination conditions can be a temperature of 300–500°C for 15–60 minutes.

[0066] 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.

[0067] 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; and phosphates in phosphate solutions are selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate.

[0068] This invention does not limit the mass ratio of each raw material. For example, the mass ratio of 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 mass ratio of phosphorus-containing filtrate to the second NaY molecular sieve is (2-10):1, more specifically (3-6):1; the rare earth metal salt, calculated as rare earth metal oxide, has a mass ratio of rare earth metal salt to the second NaY molecular sieve of (0.01-0.1):1, more specifically (0.05-0.1):1. Specifically, the first phosphate solution and the second phosphate solution, calculated as elemental phosphorus, have a mass ratio of first phosphate solution to second NaY molecular sieve of (0.005-0.05):1, and a mass ratio of second phosphate solution to a first NaY molecular sieve of (0.02-0.15):1.

[0069] 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℃, time 0.5-2h; the conditions for water washing are each independently selected from: temperature 20-100℃, and the mass ratio of water to the molecular sieve to be washed is (1-15):1; the temperature for pretreatment is 10-100℃, the temperature for drying is 20-200℃, and the conditions for calcination are: temperature 500-800℃, time 1-3h. The temperature for the first drying can be further 100-150℃, the conditions for calcination can be further 600-700℃, and the time can be 2-3h; the temperatures for the first and second water washings can be further 60-80℃, and the mass ratio of water to the molecular sieve to be washed can be further 3-5:1.

[0070] 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%.

[0071] In the implementation of this invention, the preparation of the above-mentioned molecular sieve 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:

[0072] I. Pretreatment

[0073] 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.

[0074] II. First Ion Exchange Treatment

[0075] 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.

[0076] III. Second Ion Exchange Treatment

[0077] 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.

[0078] IV. Washing

[0079] 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.

[0080] V. Preparation of Molecular Sieve Filter Cake

[0081] 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.

[0082] VI. Third Ion Exchange Treatment

[0083] 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.

[0084] VII. Preparation of Modified Y-type Molecular Sieve Catalysts

[0085] 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 filtering the third exchange product, a Y-type molecular sieve containing phosphorus and rare earth metals is obtained. The Y-type molecular sieve containing phosphorus and rare earth metals, clay, binder, and water are mixed, dried, and calcined to obtain a modified Y-type molecular sieve catalyst.

[0086] In a second aspect, the present invention provides a modified Y-type molecular sieve catalyst, prepared by the aforementioned preparation method, which has the advantage of strong heavy oil conversion capability.

[0087] 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 modified Y-type molecular sieve catalyst described in the second aspect above. Because the present invention utilizes the aforementioned modified Y-type molecular sieve catalyst as a catalyst for catalytic cracking, it can significantly improve the heavy oil conversion rate.

[0088] The present invention does not limit the specific selection of feedstock oil, for example, it can be selected from one or more of atmospheric distillate oil (AGO), atmospheric residue oil (AR), vacuum distillate oil (VGO), and vacuum residue oil (VR).

[0089] In this invention, the preheating temperature of the raw oil can be 50-120℃.

[0090] In one embodiment, introducing an oil-soluble additive into the catalytic cracking system is beneficial for further improving the heavy oil conversion rate. The additive can be added by uniformly mixing the feedstock oil and the oil-soluble additive, then contacting it with the catalyst, or by adding the feedstock oil first, then adding the additive, and finally contacting it with the catalyst. This invention does not particularly limit the catalyst preparation method, and commonly used methods in the art can be employed. The oil-soluble additive is selected from oil-soluble isooctanoates. The amount of oil-soluble additive added is 0.01%-5% of the feedstock oil mass.

[0091] In the aforementioned catalytic cracking system, by adding oil-soluble additives to the feedstock, the additives first adsorb onto the catalyst surface, altering the reaction potential of the feedstock and generating small-molecule olefins. The catalyst then reacts with these small molecules in a catalytic cracking reaction, generating a large number of carbocations, which accelerate the cracking of the feedstock. This promotes the carbocation reaction throughout the system, inhibits the thermal cracking and coking reaction, thereby improving heavy oil conversion capacity, reducing coke yield, and improving coking performance. Furthermore, adding oil-soluble additives to the feedstock has advantages such as simplicity, low cost, and small dosage. Moreover, these additives only change the product distribution in the catalytic cracking process and do not alter the quality indicators of gasoline, diesel, or other products, having no impact on subsequent processing.

[0092] This invention does not limit the specific type of oil-soluble isooctanoate, but may select one or more of oil-soluble yttrium isooctanoate, oil-soluble cerium isooctanoate, and oil-soluble antimony isooctanoate.

[0093] 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.

[0094] The reagents and materials used in the following examples and comparative examples were sourced from the following sources:

[0095] 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%.

[0096] 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%.

[0097] 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.

[0098] Kaolin, halloysite, montmorillonite, silica sol, boehmite, and aluminosilicate all come from Lanzhou Petrochemical Company.

[0099] Example 1

[0100] Preparation of modified Y-type molecular sieve catalysts

[0101] 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;

[0102] 2) Mix the second NaY molecular sieve, phosphorus-containing filtrate B (obtained in Comparative Example 1), and lanthanum chloride and 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 filter cake with a thickness of 10 mm on the filter cloth.

[0103] 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 the second NaY 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.

[0104] 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.

[0105] 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.

[0106] 40g of molecular sieve S1, 40g of pseudoboehmite, 20g of kaolin and 300g of water were mixed and slurried evenly. 4g of hydrochloric acid was added and stirred for 60 minutes. The mixture was then spray-dried and calcined to obtain catalyst F1.

[0107] Example 2

[0108] 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:

[0109] Preparation of modified Y-type molecular sieve catalysts

[0110] 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;

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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 S1 is 1.1%, and the phosphorus content and rare earth content of filtrate G are 1 ppm and 3 ppm, respectively.

[0115] 6) Preparation of molecular sieve catalyst: 25g molecular sieve S2, 15g pseudoboehmite, 60g kaolin and 120g water were mixed and slurried evenly, 4g hydrochloric acid was added and stirred for 40 minutes, and then spray dried and calcined to obtain catalyst F2.

[0116] Example 3

[0117] 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:

[0118] Preparation of modified Y-type molecular sieve catalysts

[0119] 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;

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 6) Preparation of molecular sieve catalyst: 70g molecular sieve S3, 10g aluminum sol, 20g kaolin and 80g water were mixed and stirred for 80 minutes, then spray dried and calcined to obtain catalyst F3.

[0125] Example 4

[0126] 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:

[0127] 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:first 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;

[0128] 2) Mix and slurry the second NaY molecular sieve, filtrate J, and lanthanum chloride. The mass ratio of lanthanum chloride to the second NaY 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 the mixture 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.

[0129] 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.

[0130] 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.

[0131] 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 and calcining at 500°C for 1 hour, molecular sieve sample S4 and filtrate L are obtained. The sodium oxide content of sample S4 is 1.2%, and the phosphorus content and rare earth content of filtrate L are 3 ppm and 1 ppm, respectively.

[0132] 6) Preparation of molecular sieve catalyst: Mix 3g silica sol, 49g kaolin, 19g hydrochloric acid and 230g water and beat for 120 minutes. Then add 48g molecular sieve S4 and stir evenly. Then spray dry and calcine to obtain catalyst F4.

[0133] Example 5

[0134] Preparation of modified Y-type molecular sieve catalysts

[0135] 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;

[0136] 2) Mix and pulp the phosphorus-containing filtrate B (obtained from Comparative Example 1) and lanthanum chloride. The mass ratio of lanthanum oxide to the first NaY molecular sieve is 0.03:1, and the mass ratio of phosphorus-containing filtrate B to the first NaY molecular sieve is 7:1. Prepare a solution of phosphorus-containing filtrate and rare earth metal salt. Pour the obtained solution 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 filter cake with a thickness of 10 mm on the filter cloth.

[0137] 3) When there is no liquid on the surface of the first exchange filter cake, immediately add ammonium phosphate solution at 90°C. 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 first NaY molecular sieve is 0.17:1. When there is no liquid on the surface of the filter cake, immediately add deionized water at 80°C to wash the filter cake. The weight ratio of deionized water to the first NaY molecular sieve is 3:1. The product filter cake (second exchange product) and filtrate M are obtained. Then, the product filter cake is removed and dried at 120°C and calcined at 600°C for 1 hour to obtain a first calcined molecular sieve.

[0138] 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.

[0139] 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 0.06:1. 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 4:1. Then, filter cake molecular sieve sample (Y-type molecular sieve containing phosphorus and rare earth metals) S5 and filtrate N are obtained. The sodium oxide content of sample S5 is 0.8%, and the phosphorus content and rare earth content of filtrate M are 3.7 ppm and 15 ppm, respectively.

[0140] 40g of molecular sieve S5, 40g of pseudoboehmite, 20g of kaolin and 300g of water were mixed and slurried evenly. 4g of hydrochloric acid was added and stirred for 60 minutes. The mixture was then spray-dried and calcined to obtain catalyst F5.

[0141] Comparative Example 1

[0142] The preparation of a calcined molecular sieve sample follows the method disclosed in patent document CN1485136A, specifically including the following steps:

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] The catalyst sample was prepared according to the method disclosed in patent CN1416951A, specifically including the following steps:

[0149] 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.

[0150] Catalyst preparation: 40g molecular sieve D1, 40g pseudoboehmite, 20g kaolin and 300g water were mixed and slurried evenly, 4g hydrochloric acid was added and stirred for 60 minutes, and then spray dried and calcined to obtain catalyst E1.

[0151] Comparative Example 2

[0152] Referring to the method disclosed in patent document CN108097288A, the specific steps include:

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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;

[0157] 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%.

[0158] Catalyst preparation: 40g molecular sieve D2, 40g pseudoboehmite, 20g kaolin and 300g water were mixed and slurried evenly, 4g hydrochloric acid was added and stirred for 60 minutes, and then spray dried and calcined to obtain catalyst E2.

[0159] Comparative Example 3

[0160] The preparation method is based on the method disclosed in patent document CN101722021B, and specifically includes the following steps:

[0161] 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.

[0162] 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.

[0163] Catalyst preparation: 40g molecular sieve D3, 40g pseudoboehmite, 20g kaolin and 300g water were mixed and slurried evenly, 4g hydrochloric acid was added and stirred for 60 minutes, and then spray dried and calcined to obtain catalyst E3.

[0164] Comparative Example 4

[0165] Preparation of modified Y-type molecular sieve catalysts

[0166] 1) Mix the first NaY molecular sieve with water and slurry 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 and pour it into a Buchner funnel, while simultaneously evacuating 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.

[0167] 2) Mix the second NaY molecular sieve, phosphorus-containing filtrate B (obtained in Comparative Example 1), and lanthanum chloride and 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 filter cake with a thickness of 10 mm on the filter cloth.

[0168] 3) When there is no liquid on the surface of the first exchange filter cake, immediately add ammonium phosphate solution at 90℃, ensuring 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 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 the second NaY molecular sieve is 5:1. The product filter cake (second exchange product) and filtrate O 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.

[0169] 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.

[0170] 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) D4 and filtrate P are obtained. The sodium oxide content of sample D4 is 1.8%, and the phosphorus content of filtrate O is 367 ppm and the rare earth content is 1173 ppm.

[0171] 40g of molecular sieve S1, 40g of pseudoboehmite, 20g of kaolin and 300g of water were mixed and slurried evenly. 4g of hydrochloric acid was added and stirred for 60 minutes. The mixture was then spray-dried and calcined to obtain catalyst E4.

[0172] Test case

[0173] 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.

[0174] When evaluating the selectivity of catalyst F3 in the above-mentioned catalytic cracking reaction, 0.059% of oil-soluble yttrium isooctanoate was added to the feedstock oil. The addition method was to mix it with the feedstock oil. The evaluation result obtained was F3-1, and the results are shown in Table 2.

[0175] Specific analysis methods:

[0176] 1) The content of sodium oxide, phosphorus, and rare earth oxide in the molecular sieve was analyzed by X-ray fluorescence spectrometry.

[0177] 2) Phosphorus content and rare earth metal content: detected using an ICP (Inductively Coupled Plasma Emission Spectrometer);

[0178] 3) Calculation method for rare earth utilization rate:

[0179]

[0180] 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;

[0181] V - The volume of rare earth-containing solution added, in mL;

[0182] R i - The mass of solid rare earth added (based on rare earth oxides), g;

[0183] The rare earth concentration (calculated as rare earth oxide) of the filtrate collected after Co-filter cake filtration, g / mL;

[0184] Vo - The volume of filtrate collected after filter cake filtration, in mL.

[0185] Table 1

[0186]

[0187] Table 2

[0188]

[0189] According to the molecular sieve catalyst samples prepared in the examples and comparative examples, the sodium oxide content in the molecular sieve catalyst prepared in the examples is comparable to that in the comparative examples. In the examples, there is virtually no loss of phosphorus and rare earth metals, and the utilization rate of phosphorus and rare earth metals is over 99%. However, the rare earth metal content in the molecular sieve catalyst prepared in the comparative examples is significantly lower than the feed amount. A large amount of phosphorus and rare earth metals are not exchanged onto the molecular sieve during ion exchange and are lost with the filtrate during filtration, resulting in low utilization of phosphorus and rare earth metals. Furthermore, improper treatment of phosphorus and rare earth metals in the filtrate can cause environmental pollution. Further, the molecular sieve prepared by this invention has a high introduction amount of phosphorus and rare earth metals, and the rare earth introduction amount is controllable. In particular, comparing the molecular sieve S1 obtained in Example 1 and the molecular sieve D2 obtained in Comparative Example 2, it can be seen that under the same rare earth metal usage conditions, the modified Y molecular sieve prepared by the method provided by this invention can significantly improve the utilization rate of phosphorus and rare earth metals, ensure the sodium oxide content in the molecular sieve, and not affect the performance of the molecular sieve.

[0190] The inventors have concluded through research that the conversion rate is directly related to the content of molecular sieves, the main active component in the catalyst. Table 2 shows that the F2 conversion rate is lower than that of the comparative examples, mainly due to the low molecular sieve content in the catalyst. All comparative examples have the same molecular sieve content as Example 1. Table 2 shows that using the molecular sieve catalyst provided by this invention as a catalyst for catalytic cracking of heavy oil can significantly improve the heavy oil conversion capacity. Furthermore, by adding isooctanoate, the heavy oil conversion capacity can be further improved while increasing the yield of high-value-added products.

[0191] 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 method for preparing a modified Y-type molecular sieve catalyst, characterized in that, Includes the following steps: NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid and water are mixed and pretreated to obtain pretreated molecular sieve; The pretreated molecular sieve is subjected to a first ion exchange treatment in a solution containing phosphorus-containing filtrate and rare earth metal salts. After filtration, a first exchange product and a first filtrate are obtained. The first exchange product is subjected to a second ion exchange treatment in a first phosphate solution, and after filtration, a second exchange product and a third filtrate are obtained. After drying and calcining the second exchange product, a calcined molecular sieve is obtained. Mix a batch of molecular sieve with water to form a molecular sieve filter cake. The molecular sieve filter cake was subjected to a third ion exchange treatment in a second phosphate solution. After filtration, the third exchange product and the fourth filtrate were obtained. After washing and filtering the third exchange product, a Y-type molecular sieve containing phosphorus and rare earth metals was obtained. The phosphorus- and rare earth metal-containing Y-type molecular sieve, clay, binder, 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 weight: 25-70 wt% Y-type molecular sieve containing phosphorus and rare earth metals, 20-60 wt% clay, and 3-20 wt% binder.

2. The preparation method according to claim 1, characterized in that, The first filtrate is returned for the first ion exchange treatment.

3. The preparation method according to claim 1 or 2, characterized in that, It also includes the following steps: The first NaY molecular sieve, alkali metal hydroxide, carbonate, humic acid and water were mixed and pretreated to obtain a pretreated molecular sieve. The second NaY molecular sieve, phosphorus-containing filtrate, and rare earth metal salt are mixed and slurried to form the first exchange solution. The pretreated molecular sieve undergoes the first ion exchange reaction in the first exchange solution.

4. The preparation method according to claim 1, characterized in that, The third and / or fourth filtrate is returned for the first ion exchange treatment.

5. The preparation method according to claim 1, characterized in that, The humic acid includes at least one of fulvic acid, brown humic acid, and black humic acid; and / or, The alkali metal hydroxide includes at least one of sodium hydroxide and potassium hydroxide; and / or, The carbonate includes at least one of potassium carbonate and sodium carbonate.

6. The preparation method according to claim 3, characterized in that, The first phosphate solution and the second phosphate solution are calculated based on phosphorus element. The mass ratio of the first phosphate solution to the second NaY molecular sieve is (0.005~0.05):1, and the mass ratio of the second phosphate solution to the first NaY molecular sieve is (0.02-0.15):

1.

7. The preparation method according to claim 3, characterized in that, 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, The mass ratio of the phosphorus-containing filtrate to the second NaY molecular sieve is (2~10):1; and / or, 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 conditions for the first and second ion exchange treatments are each independently selected from: temperature 50–100 °C, time 0.5–2 h; and / or, The pretreatment temperature is 10~100℃, and the drying temperature is 20~200℃.

8. A modified Y-type molecular sieve catalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. A method for catalytic cracking of heavy oil, characterized in that, Under catalytic cracking conditions, the feedstock oil is brought into contact with the catalyst to react; wherein the catalyst is the modified Y-type molecular sieve catalyst as described in claim 8.

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