Process for the preparation of a catalytic cracking catalyst resistant to vanadium

Abstract

This application discloses a method for preparing a vanadium-resistant catalyst for catalytic cracking, relating to the field of catalyst technology. The method includes the following steps: Step 1, adding a rare earth compound to ammonia water and dispersing it by stirring to obtain a dispersion; Step 2, grinding the dispersion to obtain a grinding slurry; Step 3, adding an FCC catalyst to the grinding slurry and mixing it evenly to obtain a catalytic mixed slurry; Step 4, drying the catalytic mixed slurry to obtain a core-shell structured vanadium-resistant catalyst for catalytic cracking. This application exhibits excellent and long-lasting vanadium resistance.

Description

Technical Field

[0001] This application relates to the field of catalyst technology, and in particular to a method for preparing a vanadium-resistant catalyst for catalytic cracking. Background Technology

[0002] Catalytic cracking is a crucial process in the petroleum processing industry, and catalytic cracking agents play a key role in this process to produce more economically valuable cracking products, such as gasoline, diesel, and low-carbon olefins. Simultaneously, by reducing uneconomically valuable byproducts such as coke and hydrogen, the production efficiency of petroleum catalytic cracking is effectively improved. Typically, vanadium metal complexes and large molecules such as pitch in petroleum associate to form high-molecular-weight hydrocarbons that deposit on the FCC balancer. During regeneration, vanadium oxidizes to form vanadium pentoxide. As the catalytic cracking process progresses, vanadium pentoxide combines with water vapor to form vanadic acid. Vanadic acid not only disrupts the porous alumina structure of the FCC catalyst system but also reacts with the main components of the FCC catalyst through molecular sieves to generate sodium hydroxide, thereby damaging the stability of the molecular sieve crystals, leading to molecular sieve deactivation and FCC catalyst poisoning. This shortens the catalyst's lifespan, affects the selectivity of catalytic cracking products, increases coke production, and reduces the proportion of components such as gasoline and diesel.

[0003] To reduce the destructive effect of vanadium on FCC catalysts, refineries often add vanadium scavengers or vanadium inhibitors to the catalytic cracking agent to reduce or avoid the impact of vanadium acid on the catalytic cracking agent. This practice can be traced back to 1995 when Kwan Kim of Grace Institute of Technology proposed using the Alcoa spinel system as a vanadium scavenger.

[0004] The aluminum spinel system disclosed in US Patent 5603823A comprises 15-60% magnesium oxide, 30-60% aluminum oxide, and 10-30% rare earth oxides, where the rare earths refer to lanthanum or neodymium. However, lanthanum rare earths have the ability to react with vanadate and will form chemically stable lanthanum vanadate.

[0005] Chinese patent application CN1879960A discloses a method of using kaolin to replace alumina, which is then mixed with magnesium oxide and rare earth elements, sprayed into microspheres, and washed with water to reduce sodium content, in order to obtain an additive that resists the heavy metal vanadium.

[0006] European patent application EP2280777A1 discloses a method for preparing vanadium-resistant additives using lanthanum carbonate and aluminum sol, which eliminates magnesium oxide components. Lanthanum carbonate (50%) and aluminum sol (50%) are mixed, pulped, spray-dried, and spherical particles are obtained. These particles are then calcined to produce vanadium-resistant additives.

[0007] Chinese patent application CN106378203A discloses a method for preparing a vanadium scavenging agent, which involves mixing clay and boehmite, spraying the mixture into spheres, calcining them, then mixing them with magnesium compounds and water to form a slurry, followed by leaching with rare earth chlorides to obtain the vanadium metal scavenging agent. Chinese patent application CN112831341B discloses a vanadium-resistant catalytic cracking catalyst, in which rare earth carbonates are directly added to the catalyst system during synthesis, providing a certain passivation effect on vanadium metal. US patent application US4913801A discloses the preparation of vanadium-resistant additives using rare earth oxides as passivating agents. Chinese patent application CN109777469A discloses the use of rare earth chloride exchange molecular sieves and the addition of rare earth elements to the matrix, exhibiting a certain vanadium-resistant effect.

[0008] However, although there is a wide variety of catalytic cracking agents with vanadium resistance, their vanadium resistance is not stable. Especially after multiple activations and regenerations, the vanadium resistance effect decreases significantly due to the insufficient wear resistance of the composite magnesium salt-alumina-rare earth material, which cannot match the main catalyst and the decrease in molecular sieve stability. It is difficult to achieve the desired vanadium resistance effect in the long term and needs to be improved. Summary of the Invention

[0009] In view of this, the purpose of this application is to provide a method for preparing a vanadium-resistant catalyst for catalytic cracking, so as to achieve low cost, stable and long-lasting vanadium resistance. The specific method is as follows:

[0010] A method for preparing a vanadium-resistant catalyst for catalytic cracking, comprising the following steps:

[0011] Step 1: Add the rare earth compound to ammonia water, and after stirring and dispersing, obtain a dispersion.

[0012] Step 2: Grind the dispersion to obtain a grinding slurry;

[0013] Step 3: Add FCC catalyst to the grinding slurry, mix evenly to obtain catalytic mixed slurry;

[0014] Step 4: After drying the catalytic mixture slurry, a core-shell structured vanadium-resistant catalyst for catalytic cracking is obtained.

[0015] Preferably, in step 1, the rare earth compound is one of rare earth carbonate, rare earth hydroxide, rare earth formate, rare earth oxalate, rare earth acetate, rare earth oxychloride, or rare earth oxide.

[0016] Preferably, the rare earth element in the rare earth compound is one of lanthanum, cerium, yttrium, praseodymium, neodymium, samarium, europium, and gadolinium.

[0017] Preferably, in step 1, the ammonia solution has a mass concentration of 0.1-10% and a pH value of no more than 12; the dispersion contains 1-30% rare earth compounds by mass percentage, and the stirring speed is 200-3000 rpm.

[0018] Preferably, in step 2, the grinding process is carried out using a sand mill or a nano-pin type wet mill, and the grinding beads are alumina grinding beads or zirconia grinding beads; and the grinding time is 0.1-10h, and the average particle size of the particles in the grinding slurry is 0.1-2μm.

[0019] Preferably, in step 3, the particle size of the FCC catalyst is 50-120 μm, and the loss on ignition is 2-15%; and the mass ratio of the amount of FCC catalyst added to the mass of the grinding slurry is 100:0.2-10.

[0020] Preferably, in step 4, the drying process includes flash drying or airflow drying, and the inlet temperature is controlled at 200-550℃ and the outlet temperature is controlled at 90-200℃.

[0021] Preferably, the method further includes high-temperature calcination, wherein the high-temperature calcination temperature is 500-900℃ and the time is 0.5-4h.

[0022] Preferably, the FCC catalyst is a cyclodextrin cavity-directed FCC catalyst, and the preparation of the cyclodextrin cavity-directed FCC catalyst includes step ① mixing β-CD and maleic anhydride at a molar ratio of 1:2, adding N,N-dimethylformamide as a solvent and p-toluenesulfonic acid at a mass percentage of 0.5% as a catalyst, stirring and reacting under nitrogen protection and controlled temperature of 80℃ for 6 hours, and then obtaining maleic anhydride-modified β-cyclodextrin derivatives by precipitation, washing and drying; step ② adding the FCC catalyst to an aqueous solution of β-CD-MA, controlling the mass concentration of β-CD-MA to 8%, and then sonicating for 40 minutes and stirring in a constant temperature water bath at 55℃ for 8 hours to obtain a reaction solution with a zeta potential of -30~-35mV, and then obtaining the cyclodextrin cavity-directed FCC catalyst by centrifugation, washing with deionized water and vacuum drying.

[0023] Preferably, in step 3, after adding cyclodextrin cavity-guided FCC catalyst to the grinding slurry and stirring for 0.5 h, a mixed aqueous solution of CTAB and SDBS is added dropwise, controlling the addition ratio of CTAB to SDBS to be 1:1, the dropping rate to be 1 mL / min, and the pH to be 9-10; the temperature of the catalytic mixed slurry is 45 °C, and the particle size of the vanadium-resistant catalytic cracking catalyst is 50-90 μm.

[0024] As can be seen from the above scheme, this application provides a method for preparing a vanadium-resistant catalyst for catalytic cracking, which has the following beneficial effects:

[0025] 1. By controlling the particle size of the grinding slurry to be 0.1-2μm and the particle size of the FCC catalyst to be 50-120μm, it is possible to avoid hindering the diffusion of feedstock oil molecules and improve the active sites of the FCC catalyst as the core. Furthermore, rare earth elements are used to adjust the acidity of the catalyst, thereby improving the conversion rate of feedstock oil.

[0026] 2. High-temperature calcination promotes the formation of a stable chemical bond between the rare earth shell and the FCC catalyst. Combined with flash evaporation or airflow drying processes, this improves mechanical strength and thermal stability, thereby effectively enhancing the resistance of the vanadium-resistant catalyst to repeated fluidization and high-temperature regeneration environments in catalytic cracking and extending its service life.

[0027] 3. By using a sand mill / nano pin wet mill for grinding, combined with ultrasonic treatment and heating process, the complexity of the process is reduced. The raw materials used are low cost and widely available, which meets the environmental protection and economic requirements of industrial production and is easy to promote and apply on a large scale.

[0028] 4. The β-CD-MA derivative modified on the surface of the FCC catalyst precursor through cyclodextrin cavity-guided modification enables it to capture rare earth ions in a directional manner through the cavity structure and carboxyl sites. Combined with the synergistic regulation of CTAB and SDBS dual assembly aids, rare earth compounds form a uniform and dense shell on the surface of the FCC catalyst. This shell enables the efficient adsorption and stabilization of vanadium ions in petroleum feedstocks, avoiding the damage of vanadium to the molecular sieve core structure and significantly improving the catalyst's resistance to vanadium poisoning. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0030] Figure 1 This is a flowchart of the preparation method of the vanadium-resistant catalyst for catalytic cracking disclosed in this application;

[0031] Figure 2 Electron microscope image of the FCC catalyst procured in this application;

[0032] Figure 3 This is an electron microscope image of the vanadium-resistant catalytic cracking catalyst prepared in Example 1 of this application;

[0033] Figure 4 A probe microscope image of the FCC catalyst procured in this application;

[0034] Figure 5 This is a probe microscope image of the vanadium-resistant catalytic cracking catalyst prepared in Example 1 of this application;

[0035] Figure 6 The graph shows the conversion rate test results of the vanadium-resistant catalytic cracking catalyst prepared in this application and the purchased FCC catalyst. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] It should be mentioned that the vanadium-resistant catalyst for catalytic cracking in Example 4 of this application undergoes primary impurity removal, secondary curing, and tertiary activation treatment. The primary impurity removal is centrifugal separation, with the rotation speed controlled at 6000 r / min for 20 min, and washing with 50°C deionized water. The secondary curing involves placing the catalytic mixture slurry in a muffle furnace and calcining it using a controlled program. The controlled program involves raising the temperature from room temperature to 300°C at a rate of 5°C / min and holding it for 2 h, and then raising the temperature to 550°C at a rate of 3°C / min and holding it for 4 h.

[0038] In this embodiment, the purchased FCC catalyst is AIC-950. The rare earth compound is one of rare earth carbonate, rare earth hydroxide, rare earth formate, rare earth oxalate, rare earth acetate, rare earth oxychloride, or rare earth oxide. The rare earth element in the rare earth compound is one of lanthanum, cerium, yttrium, praseodymium, neodymium, samarium, europium, or gadolinium. However, to simplify comparison, the rare earth compound in this embodiment is specifically chosen as lanthanum carbonate or lanthanum-cerium carbonate, with a lanthanum to cerium mass ratio of 4:1 in the lanthanum-cerium carbonate.

[0039] The following will describe in detail the preparation method of a vanadium-resistant catalyst for catalytic cracking according to this application.

[0040] like Figure 1 As shown, a method for preparing a vanadium-resistant catalyst for catalytic cracking includes the following steps:

[0041] Step 1: Add the rare earth compound to ammonia water with a mass concentration of 0.1-10% and a pH value of no more than 12, and disperse it by stirring at a speed of 200-3000 rpm to obtain a dispersion containing 1-30% rare earth compound by mass percentage.

[0042] Step 2: Grind the dispersion using a sand mill or a nano-pin wet mill with alumina or zirconia grinding beads. The grinding time is 0.1-10 hours, and the average particle size of the particles in the grinding slurry is 0.1-2 μm to obtain the grinding slurry.

[0043] Step 3: Add FCC catalyst with a particle size of 50-120μm and a loss on ignition of 2-15% to the grinding slurry. Control the mass ratio of the added FCC catalyst to the grinding slurry to be 100:0.2-10. After mixing evenly, obtain a catalytic mixed slurry.

[0044] Step 4: After drying the catalytic slurry, the drying process is controlled, including flash drying or airflow drying, and the inlet temperature is controlled at 200-550℃ and the outlet temperature is controlled at 90-200℃ to obtain a core-shell structured vanadium-resistant catalytic cracking catalyst.

[0045] To further improve the thermal stability of the vanadium-resistant catalyst for catalytic cracking, the drying process also includes high-temperature calcination, with a temperature of 500-900℃ and a time of 0.5-4h.

[0046] It should be mentioned that, in order to improve the service life and catalytic cracking effectiveness of the obtained vanadium-resistant catalytic cracking catalyst based on environmental protection and cost control, the FCC catalyst used in this application is a cyclodextrin cavity-directed FCC catalyst. The preparation of the cyclodextrin cavity-directed FCC catalyst includes the following steps: Step ①: β-CD and maleic anhydride are mixed at a molar ratio of 1:2, N,N-dimethylformamide is added as a solvent and p-toluenesulfonic acid at a mass percentage of 0.5% as a catalyst, and the mixture is stirred for 6 hours under nitrogen protection and at a controlled temperature of 80°C. Then, the mixture is precipitated, washed and dried to obtain a maleic anhydride-modified β-cyclodextrin derivative. Step ②: The FCC catalyst is added to an aqueous solution of β-CD-MA, and the mass concentration of β-CD-MA is controlled at 8%. The mixture is then subjected to ultrasonic treatment for 40 minutes and stirred in a constant temperature water bath at 55°C for 8 hours to obtain a reaction solution with a zeta potential of -30 to -35 mV. After centrifugation, washing with deionized water and vacuum drying, the FCC catalyst precursor is obtained. After adding FCC catalyst precursor to the grinding slurry and stirring for 0.5 h, a mixed aqueous solution of CTAB and SDBS was added dropwise, controlling the addition ratio of CTAB to SDBS to be 1:1, the dropping rate to be 1 mL / min, and the pH to be 9-10. At this time, the temperature of the catalytic mixture slurry was controlled at 45℃, and the particle size of the obtained vanadium-resistant catalytic cracking catalyst was 50-90 μm.

[0047] Example 1

[0048] A method for preparing a vanadium-resistant catalyst for catalytic cracking, comprising the following steps:

[0049] Step 1: Add 111g of lanthanum carbonate with 45% REO content purchased from Ningbo Zhanjie Materials Co., Ltd. to 500g of ammonia water with a mass concentration of 3%, and disperse it by stirring at 100rpm to obtain a dispersion.

[0050] Step 2: Grind the dispersion using a TYEE-0.3L nano-grind mill with alumina grinding beads until the average particle size of the particles in the slurry is 0.6μm.

[0051] Step 3: Add FCC catalyst to the grinding slurry, and control the mass ratio of the added FCC catalyst to the grinding slurry to be 500:157.5. After mixing evenly, a catalytic mixed slurry is obtained.

[0052] Step 4: After drying the catalytic mixture slurry, the drying process is controlled by using an XSG laboratory flash dryer, with the inlet temperature controlled at 310℃ and the outlet temperature controlled at 135℃, to obtain a core-shell structured vanadium-resistant catalytic cracking catalyst.

[0053] To further improve the thermal stability of the vanadium-resistant catalyst for catalytic cracking, the drying process also includes high-temperature calcination at 600°C for 2 hours.

[0054] It should be mentioned that, in order to improve the service life and catalytic cracking effectiveness of the obtained vanadium-resistant catalytic cracking catalyst based on environmental protection and cost control, the FCC catalyst used in this application is a cyclodextrin cavity-directed FCC catalyst. The preparation of the cyclodextrin cavity-directed FCC catalyst includes the following steps: Step ①: β-CD and maleic anhydride are mixed at a molar ratio of 1:2, N,N-dimethylformamide is added as a solvent and p-toluenesulfonic acid at a mass percentage of 0.5% as a catalyst, and the mixture is stirred for 6 hours under nitrogen protection and at a controlled temperature of 80°C. Then, the mixture is precipitated, washed and dried to obtain a maleic anhydride-modified β-cyclodextrin derivative. Step ②: The FCC catalyst is added to an aqueous solution of β-CD-MA, and the mass concentration of β-CD-MA is controlled at 8%. The mixture is then subjected to ultrasonic treatment for 40 minutes and stirred in a constant temperature water bath at 55°C for 8 hours to obtain a reaction solution with a zeta potential of -30 to -35 mV. After centrifugation, washing with deionized water and vacuum drying, the FCC catalyst precursor is obtained. After adding FCC catalyst precursor to the grinding slurry and stirring for 0.5 h, a mixed aqueous solution of CTAB and SDBS was added dropwise, controlling the addition ratio of CTAB to SDBS to be 1:1, the dropping rate to be 1 mL / min, and the pH to be 9-10. At this time, the temperature of the catalytic mixture slurry was controlled at 45℃, and the particle size of the obtained vanadium-resistant catalytic cracking catalyst was 50-90 μm.

[0055] Example 2

[0056] The difference between Example 2 and Example 1 is that the grinding time in Example 2 is 3 hours, and the average particle size of the particles in the grinding slurry is 0.3 μm.

[0057] Example 3

[0058] The difference between Example 3 and Example 1 is that the grinding time in Example 3 is 0.5h, and the average particle size of the particles in the grinding slurry is 2μm.

[0059] Example 4

[0060] The difference between Example 4 and Example 1 is that the ammonia concentration in Example 4 is 10% and the pH value is 12.

[0061] Example 5

[0062] The difference between Example 5 and Example 1 is that the ammonia concentration in Example 5 is 0.50% and the pH value is 7.5.

[0063] Example 6

[0064] The difference between Example 6 and Example 1 is that the dispersion in Example 6 contains 20% lanthanum carbonate by mass percentage.

[0065] Example 7

[0066] The difference between Example 7 and Example 1 is that the dispersion in Example 7 contains 3% lanthanum carbonate by mass percentage.

[0067] Example 8

[0068] The difference between Example 8 and Example 1 is that the mass ratio of lanthanum carbonate slurry to FCC catalyst in Example 8 is 1:50.

[0069] Example 9

[0070] The difference between Example 9 and Example 1 is that the mass ratio of lanthanum carbonate slurry to FCC catalyst in Example 9 is 1:20.

[0071] Example 10

[0072] A method for preparing a vanadium-resistant catalyst for catalytic cracking, comprising the following steps:

[0073] Step 1: Add 111g of lanthanum carbonate with 45% REO content purchased from Ningbo Zhanjie Materials Co., Ltd. to 500g of ammonia water with a mass concentration of 3%, and disperse it by stirring at 100rpm to obtain a dispersion.

[0074] Step 2: Grind the dispersion using a TYEE-0.3L nano-grind mill with alumina grinding beads until the average particle size of the particles in the slurry is 0.6μm.

[0075] Step 3: Add cyclodextrin cavity-directed FCC catalyst to the grinding slurry, controlling the mass ratio of the added FCC catalyst to the grinding slurry to be 500:157.5. After adding the cyclodextrin cavity-directed FCC catalyst to the grinding slurry and stirring for 0.5 h, add a mixed aqueous solution of CTAB and SDBS dropwise, controlling the addition ratio of CTAB to SDBS to be 1:1, the dropping rate to be 1 mL / min, the pH to be 9-10, and the temperature of the catalytic mixture to be 45℃. After mixing evenly, the catalytic mixture is obtained.

[0076] Step 4: After drying the catalytic slurry, the drying process is controlled, including flash drying or airflow drying, and the inlet temperature is controlled at 200-550℃ and the outlet temperature is controlled at 90-200℃, to obtain a core-shell structure vanadium-resistant catalyst for catalytic cracking with a particle size of 50-90μm.

[0077] To further improve the thermal stability of the vanadium-resistant catalyst for catalytic cracking, the drying process also includes high-temperature calcination at 600°C for 2 hours.

[0078] It should be mentioned that the preparation of the cyclodextrin cavity-directed FCC catalyst includes the following steps: Step ① β-CD and maleic anhydride are mixed at a molar ratio of 1:2, N,N-dimethylformamide is added as a solvent and p-toluenesulfonic acid at a mass percentage of 0.5% as a catalyst, and the reaction is carried out under nitrogen protection and at a controlled temperature of 80℃ for 6 hours. Then, the maleic anhydride-modified β-cyclodextrin derivative is obtained by precipitation, washing and drying. Step ② The FCC catalyst is added to an aqueous solution of β-CD-MA, and the mass concentration of β-CD-MA is controlled at 8%. The solution is subjected to ultrasonic treatment for 40 minutes and stirring in a constant temperature water bath at 55℃ for 8 hours to obtain a reaction solution with a zeta potential of -30~-35mV. After centrifugation, washing with deionized water and vacuum drying, the cyclodextrin cavity-directed FCC catalyst is obtained.

[0079] test:

[0080] First, standard performance tests were conducted based on Examples 1 to 9 above, specifically including rare earth content (%) and packing density (g / cm³). 3 ), pore volume (cm) 3 / g), abrasion (%), total specific surface area (cm²) 2 / g), microporous specific surface area (cm) 2 / g) and matrix specific surface area (cm) 2 / g), the results are shown in Table 1 below.

[0081] Table 1 Physicochemical properties of vanadium-resistant catalysts for catalytic cracking in each embodiment

[0082]

[0083] As shown in Table 1 above, comparing the physicochemical properties of the AIC950 catalyst and the vanadium-resistant catalyst for catalytic cracking prepared in this application, it can be seen that the physical properties of the vanadium-resistant catalyst for catalytic cracking prepared in this application are similar to those of the AIC950 catalyst. The wear, packing density, and specific surface area are all within the same measurement error range, thus effectively ensuring that the fluidization state of the catalyst remains unchanged during commercial application in refineries, facilitating catalyst replacement. The chemical properties are also identical, and the vanadium-resistant catalyst for catalytic cracking prepared in this application has a high rare earth content, effectively ensuring that the catalyst captures metallic vanadium and protects its activity.

[0084] Secondly, tests were conducted on the physicochemical properties of the oil used, specifically including specific gravity (15 degrees) (g / cm³). 3 The residual carbon (%), hydrogen content (%), Na (ppm), V (ppm), Ni (ppm), Fe (ppm), nitrogen and sulfur were measured, and the results are shown in Table 2 below.

[0085] Table 2 Physical and chemical properties of oil products

[0086]

[0087] As can be seen from Table 2 above, petroleum products contain vanadium.

[0088] The physicochemical properties of the samples after deactivation treatment in Examples 1 to 9 were tested, specifically including alumina content (%), sodium oxide content (%), rare earth content (%), and packing density (g / cm³). 3 ), pore volume (cm) 3 / g), abrasion (%), total specific surface area (cm²) 2 / g), microporous specific surface area (cm) 2 / g), matrix specific surface area (cm) 2 The results of the residual microporous surface area (%) and the microporous surface area (%) are shown in Table 3 below.

[0089] Table 3 Physicochemical properties of vanadium-resistant catalysts in each embodiment after deactivation treatment

[0090]

[0091] The deactivation conditions are as follows: deactivation according to ASTM D7964 / D7964M-14, or, in other words, impregnation of the catalyst using an equal-volume impregnation method to achieve a vanadium content of 3000 ppm, followed by treatment at 810°C and 100% steam for 24 hours. Figure 2 It can be seen that the vanadium-resistant catalyst for catalytic cracking obtained through the embodiments of this application is similar to the original catalyst, both being spherical with smooth outer surfaces. Further electron probe microanalysis reveals... Figure 4As shown, the rare earth element lanthanum is uniformly distributed on the original particles, with a content of only 1.0%. In contrast, the rare earth element in the vanadium-resistant catalyst for catalytic cracking of this application is concentrated on the outside of the particles, forming a ring layer, and the rare earth content increases to 3-5%.

[0092] Figure 4 Compared with the AIC950 catalyst, the gasoline yield of the vanadium-resistant catalytic cracking catalyst prepared in this application is significantly improved by 1-3%, thus its vanadium resistance effect is significantly enhanced.

[0093] As shown in Table 3 above, the physicochemical properties of the deactivated AIC-950 catalyst and the vanadium-resistant catalyst for catalytic cracking prepared in this application were compared. By impregnating the catalysts using the equal-volume impregnation method to achieve the set vanadium content of 3000 ppm, the microporous specific surface area of ​​the AIC-950 catalyst was significantly reduced, with a residual specific surface area of ​​only 43%, indicating significant destruction of the molecular sieve structure and resulting in a low gasoline yield. The vanadium-resistant catalyst for catalytic cracking prepared in this application had a residual specific surface area as high as 68%, indicating better retention of the molecular sieve within the catalyst, resulting in a higher gasoline yield from catalytic cracking and a significant vanadium-resistant effect.

[0094] Performance testing was conducted on Example 10, and the testing method is as follows:

[0095] ①1. A small fixed fluidized bed reactor (ACE device) was used, with the oil products described in Table 2 as raw materials (V content 17.9ppm), and an additional oil-soluble vanadium compound (such as vanadium naphthenate) was added to increase the total V content of the raw materials to 2000μg / g;

[0096] 2. Control reaction conditions: reaction temperature 520℃, agent-to-oil ratio 3.5, residence time 2.5s, continuous operation for 300h, sampling and measuring feed oil conversion rate every 50h;

[0097] 3. Control group: Simultaneous testing of Example 1 and AIC-950 catalyst, with all other conditions being completely identical.

[0098] ②1. After the reaction is complete, the catalyst sample is cut into sections by focused ion beam scanning electron microscopy (FIB-SEM) to obtain ultrathin sections with a thickness of 100 nm.

[0099] 2. Using a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) combined with an X-ray energy dispersive spectroscopy (EDS), vanadium element line scans were performed on the slices from the surface to the core (5 nm interval), and V content-depth distribution curves were plotted.

[0100] ③1. X-ray diffraction (XRD) was used to determine the characteristic peaks of the molecular sieve in the deactivated catalyst: the characteristic peaks of the Y-type molecular sieve were 2θ=6.2°, 10.1°, and 15.8°;

[0101] 2. Calculate the characteristic peak intensity retention rate: (Integrated intensity of characteristic peak after deactivation / Integrated intensity of characteristic peak of fresh catalyst) × 100%;

[0102] 3. The distribution of acidic sites was determined by ammonia temperature-programmed desorption (NH3-TPD), and the ratio of Brønsted acid (bridging hydroxyl group) to Lewis acid (Lewis acid) was calculated.

[0103] The test results are shown in Table 4 below.

[0104] Table 4 Performance Test Results of Example 10

[0105]

[0106] like Figure 3 , Figure 5 , Figure 6 As shown in Table 4 above, cyclodextrin cavities directionally capture rare earth ions, forming a dual barrier of "dense rare earth shell and atomic-level anchoring points," thus preventing V... 5+ Diffusion into the molecular sieve core; the dual assembling agent composed of CTAB and SDBS regulates the shell pore size, allowing feed molecules to enter while intercepting vanadium ions. The carboxyl group of β-CD-MA reacts with Ce. 3+ Stable coordination bonds are formed, making the rare earth shell a trapping site for vanadium; the cationic properties of CTAB enhance the shell's adsorption capacity for anionic vanadium species, reducing deep penetration. Simultaneously, the rare earth shell forms stable CeVO4 with vanadium, preventing V2O5 melting and damage to the molecular sieve framework; the supramolecular effects of cyclodextrin derivatives protect the acidic sites of the molecular sieve, reducing Brønsted acid loss.

[0107] In summary, this application provides a method for preparing a vanadium-resistant catalyst for catalytic cracking. This method controls the particle size of the grinding slurry to 0.1-2 μm and the FCC catalyst particle size to 50-120 μm, thereby avoiding hindering the diffusion of feedstock molecules and increasing the active sites of the FCC catalyst as the core. Furthermore, rare earth elements are used to adjust the catalyst acidity, thereby improving the feedstock conversion rate. Simultaneously, high-temperature calcination promotes a stable chemical bond between the rare earth shell and the FCC catalyst. Combined with flash evaporation or airflow drying processes, this improves mechanical strength and thermal stability, effectively enhancing the vanadium-resistant catalyst's tolerance to repeated fluidization and high-temperature regeneration environments in catalytic cracking, and extending its service life. The grinding process utilizes a sand mill / nano-pin wet mill, combined with ultrasonic treatment and heating processes to reduce process complexity. The raw materials used are low-cost and widely available, meeting the environmental and economic requirements of industrial production and facilitating large-scale application. Through the embodiments of this application, it was found that after using β-CD-MA derivatives to modify the surface of FCC catalyst precursors with cyclodextrin cavity-directed modification, rare earth ions can be captured in a directional manner through the cavity structure and carboxyl sites. Combined with the synergistic regulation of CTAB and SDBS dual assembly aids, rare earth compounds form a uniform and dense shell on the surface of the FCC catalyst. This shell enables efficient adsorption and stabilization of vanadium ions in petroleum feedstocks, avoids the damage of vanadium to the molecular sieve core structure, and significantly improves the catalyst's resistance to vanadium poisoning.

[0108] The terms “first,” “second,” “third,” “fourth,” etc., used in this application (if applicable) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, or apparatus.

[0109] It should be noted that the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0110] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A process for the preparation of a vanadium resistant catalytic cracking catalyst, for the preparation of a vanadium resistant catalytic cracking catalyst, characterized in that, Includes the following steps: Step 1: Add the rare earth compound to ammonia water, and after stirring and dispersing, obtain a dispersion. Step 2: Grind the dispersion to obtain a grinding slurry with an average particle size of 0.1-2 μm; Step 3: Add FCC catalyst to the grinding slurry, mix evenly to obtain catalytic mixed slurry; Step 4: After drying the catalytic mixture slurry, it is calcined at high temperature to obtain a core-shell structured vanadium-resistant catalytic cracking catalyst; wherein, The FCC catalyst is a cyclodextrin cavity-directed FCC catalyst; The preparation of the cyclodextrin cavity-directed FCC catalyst includes step ① mixing β-CD and maleic anhydride at a molar ratio of 1:2, adding N,N-dimethylformamide as a solvent and p-toluenesulfonic acid at a mass percentage of 0.5% as a catalyst, and stirring the mixture under nitrogen protection and at a controlled temperature of 80℃ for 6 hours. The mixture is then subjected to precipitation, washing, and drying to obtain a maleic anhydride-modified β-cyclodextrin derivative. Step ② adding the FCC catalyst to an aqueous solution of β-CD-MA, controlling the mass concentration of β-CD-MA to 8%, and then subjecting the mixture to ultrasonic treatment for 40 minutes and stirring in a constant temperature water bath at 55℃ for 8 hours to obtain a reaction solution with a Zeta potential of -30 to -35 mV. The solution is then centrifuged, washed with deionized water, and vacuum dried to obtain the cyclodextrin cavity-directed FCC catalyst. The drying process includes either flash drying or airflow drying.

2. The process for preparing a catalytic cracking catalyst resistant to vanadium according to claim 1, characterized in that: In step 1, the rare earth compound is one of rare earth carbonate, rare earth hydroxide, rare earth formate, rare earth oxalate, rare earth acetate, rare earth oxychloride, or rare earth oxide.

3. The process for preparing a catalytic cracking anti-vanadium catalyst according to claim 2, characterized in that: The rare earth element in the rare earth compound is one of lanthanum, cerium, yttrium, praseodymium, neodymium, samarium, europium, and gadolinium.

4. The method for preparing a vanadium-resistant catalyst for catalytic cracking according to claim 1, characterized in that: In step 1, the ammonia solution has a mass concentration of 0.1-10% and a pH value of no more than 12; the dispersion contains 1-30% rare earth compounds by mass percentage, and the stirring speed is 200-3000 rpm.

5. The process for preparing a catalytic cracking anti-vanadium catalyst according to claim 1, characterized in that: In step 2, the grinding process is carried out using a sand mill or a nano-pin type wet mill, and the grinding beads are alumina grinding beads or zirconia grinding beads; and the grinding process takes 0.1-10 hours.

6. The process for preparing a catalytic cracking catalyst resistant to vanadium according to claim 1, characterized in that: In step 3, the FCC catalyst has a particle size of 50-120 μm and a loss on ignition of 2-15%; and the mass ratio of the added FCC catalyst to the grinding slurry is 100:0.2-10.

7. The process for preparing a catalytic cracking catalyst resistant to vanadium according to claim 1, characterized in that: In step 4, the inlet temperature of the flash evaporation or airflow drying is controlled to be 200-550℃ and the outlet temperature is controlled to be 90-200℃.

8. The method for preparing a vanadium-resistant catalyst for catalytic cracking according to claim 1, characterized in that: The high-temperature roasting temperature is 500-900℃, and the time is 0.5-4h.

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