A process for the preparation of a vanadium resistant catalytic cracking catalyst

Abstract

The application discloses a preparation method of a vanadium-resistant catalytic cracking catalyst, which comprises the following steps: S1, mixing and grinding waste catalysts with alkali, then mixing the waste catalysts with kaolin and a binder, beating, spraying, and preparing spray microspheres; S2, after the spray microspheres are converted into high-kaolin balls through high-temperature calcination, the high-kaolin balls are mixed with water, lye, a silicon source and a directing agent, and crystallization is carried out to obtain NaY / kaolin composite microspheres; and S3, the NaY / kaolin composite microspheres are subjected to ammonium salt and rare earth compound exchange, calcination and anti-vanadium component precipitation to obtain the vanadium-resistant catalytic cracking catalyst. The waste catalysts are mixed and ground, then mixed with kaolin and beaten to prepare spray microspheres, and a vanadium-resistant catalytic cracking catalyst is obtained through high-temperature calcination, in-situ crystallization and modification. The waste catalysts are subjected to grinding treatment with alkali, the silicon-aluminum source in the waste catalysts is better activated, and the reaction activity of the waste catalysts is improved.

Description

Technical Field

[0001] This invention belongs to the field of catalytic cracking technology, specifically relating to a method for preparing a vanadium-resistant catalytic cracking catalyst. Background Technology

[0002] Catalytic cracking is an important secondary processing method for crude oil. With the increasing weight and deterioration of feedstocks for catalytic cracking, there is a need to further improve the reaction performance of catalytic cracking catalysts. Compared with conventional FCC feedstocks (such as AGO and VGO), residue or heavy oil contains significantly higher levels of metals such as Ni, V, Fe, and Cu, which severely contaminate FCC catalysts. Nickel and vanadium have the greatest impact, depositing on the catalyst and leading to decreased cracking activity and poor product selectivity. Especially when vanadium content is high, it can destroy the molecular sieve structure, resulting in complete catalyst deactivation. Furthermore, vanadium can cause overload of the gas compressor and blower in FCC units, increase regenerator temperature, accelerate fresh catalyst replenishment, increase energy consumption, and reduce the single-pass conversion rate of the FCC unit. Developing vanadium-resistant catalytic cracking catalysts can reduce catalyst consumption, improve product distribution, and increase light oil yield, making it an important direction for catalyst development.

[0003] US4750988 discloses a vanadium scavenging agent using MgO as the active vanadium-scavenging material (mass fraction of 5%–35%), with a specific surface area of ​​100–500 μm. 2 The vanadium scavenger is present in a 10%–15% proportion in the system, with Al2O3 as the carrier. The ratio of n(MgO):n(Al2O3) is (0.01–2):1, with the optimal range being (0.05–0.5):1. The mixture may also contain 0.1%–2% vanadium oxide. This vanadium scavenger is produced by impregnating magnesium compounds onto Al2O3, followed by drying and calcination. It can improve the conversion rate and selectivity of the feedstock and increase the gasoline yield.

[0004] Exxon Corporation discloses a cracking catalyst containing alkaline earth metal compounds in US 4824815 and US 4944864. Results show that among various catalysts containing alkaline earth metals, catalysts containing strontium carbonate and calcium carbonate exhibit better resistance to vanadium contamination compared to magnesium and barium salts. CN99109680.0 and CN00122001.2 both use rare earth oxides as the vanadium-resistant component. In CN00122001.2, the amount of RE2O3 added is 3-12%. This additive has advantages such as high cracking activity, strong vanadium resistance, structural stability, and flexible application. Using this additive can significantly improve the reactivity of FCC catalysts, and is particularly suitable for catalytic cracking units with high vanadium feedstocks. CN00122003.9 describes a method for preparing an FCC catalyst resistant to heavy metals, in which 1-25 m% of a metal trapping component is added. This metal trapping component is a rare earth oxide, such as rare earth oxalate. This catalyst has excellent resistance to heavy metals and is suitable for cracking heavy oil with high Ni and V content.

[0005] The vanadium-resistant catalytic cracking catalysts reported above for industrial applications mainly consist of active components such as alumina, rare earth elements, and alkaline earth metals. These active components react with vanadium to generate more stable compounds, thus achieving the vanadium-resistant effect.

[0006] In-situ crystallization catalysts are an important component of catalytic cracking catalysts, possessing a natural advantage in resisting heavy metals, which is related to their unique preparation process. USP 4836913 reports that alkali-extracted spinel / mullite exhibits excellent heavy oil conversion capacity and resistance to metal contamination. In-situ crystallization catalysts are typically obtained by further in-situ growth and modification of Y-type zeolite from kaolin microspheres (high-kaolin and semi-kaolin microspheres) calcined at high and medium temperatures. After high-temperature calcination, kaolin is transformed into the spinel / mullite phase, and the in-situ crystallization process is accompanied by partial alkali extraction. This process gives the in-situ crystallization catalyst good vanadium resistance. To improve the vanadium resistance of the in-situ crystallization catalyst, high-kaolin microspheres should be used for preparation whenever possible; however, when high-kaolin microspheres are used directly for crystallization, the crystallinity is often low. Y-type molecular sieves are the main active component of the catalyst; to improve the cracking performance of the catalyst, in-situ crystallization catalysts are often prepared by mixing high-kaolin and semi-kaolin microspheres. Therefore, directly using high-sodium balls to prepare vanadium-resistant catalytic cracking catalysts requires further increasing their molecular sieve content.

[0007] Catalytic cracking units generate a large amount of spent catalyst during operation. Initially, this was largely handled through landfilling, resulting in the presence of heavy metals in the catalysts and contributing to groundwater and soil pollution. In 2016, catalytic cracking catalysts were included in the "National Hazardous Waste List," prohibiting indiscriminate landfilling and significantly increasing the cost of catalyst disposal. Extensive research has focused on the recycling and reuse of spent catalytic cracking catalysts. The main component of these catalysts is silicon-aluminum, which can be used as raw materials for molecular sieve growth.

[0008] For example, CN109305688A discloses a method for synthesizing NaA molecular sieves by using spent catalysts as part of the raw materials and adding sodium aluminate, sodium silicate, sodium hydroxide, etc. Yang Guidong et al. (Journal of Inorganic Chemistry, 2009, 25, 2, 201-205) synthesized NaY zeolite raw powder hydrothermally by using spent catalysts activated by alkali dissolution as aluminum sources and adding some silicon sources.

[0009] Reports on using spent catalysts as part of the raw material for in-situ crystallization catalyst preparation are rare. Zheng Shuqin et al. reported a method for synthesizing molecular sieve composite materials from spent catalysts (China Petroleum Processing & Petrochemical Technology, 2015, 17, 4: 46-54). In this method, spent catalyst is first mixed with ammonium sulfate at a mass ratio of 1:1, then calcined at 550℃. The calcined spent catalyst is then modified with hydrochloric acid. The modified spent catalyst is then mixed with calcined kaolin microspheres and crystallized to obtain a NaY / kaolin composite. This method is complex, consumes a large amount of ammonium salt, and the abrasion index of the spent catalyst increases significantly after hydrochloric acid treatment. Although the abrasion index decreases as the molecular sieve grows, breakage easily occurs under stirring conditions during the initial crystallization stage, resulting in a large number of fine particles. The separation, recovery, and utilization of these fine particles pose significant environmental challenges.

[0010] CN102247880A discloses an in-situ crystallization cracking catalyst and its preparation method. The catalyst is synthesized in situ using fine powder from spent catalytic cracking catalyst as raw material. The preparation method involves first removing heavy metal components such as vanadium and nickel from the spent catalyst using acid washing. Then, a mixture of the acid-washed spent catalyst and alkali is calcined at high temperature to activate it. The activated spent catalyst is then spray-dried with water glass, kaolin, additives, dispersants, and / or binders to form microspheres A. Microspheres A are then crystallized with water glass, water, and a directing agent to obtain crystallized microspheres with a NaY zeolite content of 20-70% and a zeolite silica-alumina ratio of 4.0-6.0. These microspheres are subsequently calcined, filtered, washed, and treated with NH4. + and / or RE 3 +Cracking catalyst products are obtained through alternating and / or phosphorus exchange. This catalyst exhibits strong resistance to heavy metals, high cracking activity, good activity stability, simple preparation process, and low cost. However, this method utilizes fine powder from spent catalyst, which constitutes a relatively small proportion of the spent catalyst. Furthermore, the method involves sequential acid treatment and high-temperature alkali roasting activation, resulting in a long process and high energy consumption.

[0011] Utilizing spent catalysts for in-situ crystallization reactions offers two advantages: firstly, it effectively treats the spent catalysts; secondly, it provides a raw material for synthesizing in-situ crystallized Y-type molecular sieves, reducing the preparation cost of the in-situ crystallization catalyst. However, methods for preparing catalysts that utilize spent catalytic cracking catalysts to increase the content of in-situ crystallized Y-type molecular sieves and further obtain vanadium resistance require further development. Summary of the Invention

[0012] The purpose of this invention is to provide a method for preparing a vanadium-resistant catalytic cracking catalyst. The vanadium-resistant catalytic cracking catalyst prepared by this method is obtained by in-situ crystallization of high-soil balls, and has low oil slurry yield and high total liquid yield when processing high-vanadium feedstock.

[0013] To achieve the above objectives, the present invention provides a method for preparing the vanadium-resistant catalytic cracking catalyst, comprising the following steps:

[0014] S1, the waste catalyst is mixed and ground with alkali, then mixed with kaolin and binder, pulped, sprayed, and made into spray microspheres;

[0015] S2, after the sprayed microspheres are calcined at high temperature to transform into high-kaolin balls, they are mixed with water, alkaline solution, silicon source and directing agent, and crystallized to obtain NaY / kaolin composite microspheres;

[0016] S3, NaY / kaolin composite microspheres were subjected to ammonium salt and rare earth compound exchange, calcined, and vanadium-resistant components were precipitated to obtain vanadium-resistant catalytic cracking catalyst.

[0017] The method for preparing the vanadium-resistant catalytic cracking catalyst of the present invention uses an alkali in step S1 that is known in the art and is not specifically limited. It can be an inorganic alkali or an organic alkali, preferably sodium hydroxide and / or sodium carbonate. The amount of alkali added, calculated as a metal oxide, is 2 to 20% of the mass of the waste catalyst, preferably 5 to 15%.

[0018] In the preparation method of the vanadium-resistant catalytic cracking catalyst of the present invention, in step S1, the particle size of the ground waste catalyst is less than 2.0 μm. The present invention does not specifically limit the grinding equipment; the median particle size D50 of the ground kaolin only needs to meet the requirements of the present invention. The grinding method is not specifically limited; dry grinding or wet grinding can be used.

[0019] In the preparation method of the vanadium-resistant catalytic cracking catalyst of the present invention, in step S1, the solid content of the mixed slurry formed by grinding the waste catalyst and alkali and mixing it with kaolin is 30-50%.

[0020] In the preparation method of the vanadium-resistant catalytic cracking catalyst of the present invention, in step S1, the particle size of the spray microspheres is 20-110 μm.

[0021] The preparation method of the vanadium-resistant catalytic cracking catalyst of the present invention, by mass, has a waste catalyst content of 5%-30% in the spray microspheres.

[0022] The method for preparing the vanadium-resistant catalytic cracking catalyst of the present invention uses kaolin, which is one or more of hard kaolin, soft kaolin and coal gangue, with a particle size of 2.5-3.5 μm, a crystalline kaolinite content of more than 80%, iron oxide content of less than 1.7%, and the sum of sodium oxide and potassium oxide of less than 0.5%.

[0023] In the preparation method of the vanadium-resistant catalytic cracking catalyst of the present invention, in step S2, the alkaline solution and its amount are known to those skilled in the art, and sodium hydroxide is preferred. There is no particular limitation on the directing agent; any ordinary directing agent can be used, such as one with a molar ratio of (14-16)SiO2:(0.7-1.3)Al2O3:(14-16)Na2O:(300-330)H2O, prepared according to the method described in CN1081425A.

[0024] In the preparation method of the vanadium-resistant catalytic cracking catalyst of the present invention, in step S2, the high-temperature calcination conditions are calcination at 920-1000℃ for 1-3 hours.

[0025] In the preparation method of the vanadium-resistant catalytic cracking catalyst of the present invention, in step S1, the amount of binder added is 2% to 10% of the total mass of the waste catalyst and kaolin.

[0026] The preparation method of the vanadium-resistant catalytic cracking catalyst of the present invention uses a binder whose type and amount are known to those skilled in the art and are not particularly limited by the present invention. The binder can be one or more of sodium silicate, silica sol, alumina sol and boehmite, and its main function is to act as a dispersant or to improve the wear resistance of the catalyst.

[0027] In the preparation method of the vanadium-resistant catalytic cracking catalyst, in step S3, the ammonium salt is one or more of ammonium sulfate, ammonium chloride, ammonium nitrate and ammonium phosphate, preferably ammonium chloride and / or ammonium nitrate; the rare earth compound is one or more of rare earth chloride and rare earth nitrate.

[0028] In the preparation method of the vanadium-resistant catalytic cracking catalyst, in step S3, the vanadium-resistant component is an alkaline earth metal and / or a rare earth metal.

[0029] The method for preparing the vanadium-resistant catalytic cracking catalyst of the present invention wherein the rare earth and alkaline earth metals in the vanadium-resistant component are calculated as oxides, and the mass ratio of the rare earth and alkaline earth metals to the vanadium-resistant catalytic cracking catalyst is 0.02-0.07.

[0030] In this invention, the exchange, calcination, and precipitation in step S3 are common techniques for in-situ crystallization catalyst preparation, and are not particularly limited in this invention. During the exchange process, the exchange substances are ammonium salts and rare earth elements. The exchange substances can be introduced simultaneously or separately. The number of exchanges is not limited; single or multiple exchanges can be performed. In multiple exchanges, the exchange substances can be the same or different each time. Calcination can be performed under 0-100% steam conditions, and the calcination process can be a single calcination or multiple calcinations. The exchange and calcination processes only need to meet the requirements of the final catalyst. The recommended exchange and calcination process conditions are: exchange at pH = 3-6 and temperature 60-100℃; calcination temperature 500-800℃, time 0.5-2 hours, and steam content 0-100%. The recommended precipitation process is: precipitation at pH = 6-9 and temperature 60-100℃. Ammonia water is preferred as the precipitant.

[0031] Beneficial effects of this invention:

[0032] This invention involves mixing and grinding spent catalyst, followed by mixing and slurrying with kaolin to prepare spray microspheres. These microspheres are then subjected to high-temperature calcination, in-situ crystallization, and modification to obtain a vanadium-resistant catalytic cracking catalyst. Grinding the spent catalyst with alkali refines it and enhances the activation of the silicon-aluminum source within, improving its reactivity. Simultaneously, the primary and secondary molecular sieve structural units and incompletely destroyed molecular sieve crystals from the spent catalyst contained in the spray microspheres act as structural guides during the growth of Y-type molecular sieves, inducing the formation of more Y-type molecular sieves and optimizing their distribution inside and outside the microspheres. The catalyst prepared using this invention exhibits higher crystallinity and pore volume of the Y-type molecular sieves. Furthermore, it effectively reduces the damage to the active component, the Y-type molecular sieve, caused by vanadium when processing high-vanadium raw materials, resulting in lower oil slurry yield and higher total liquid yield. Detailed Implementation

[0033] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0034] Analytical methods

[0035] The phase composition and crystallinity of the NaY / kaolin composite microspheres were characterized using a Rigaku D / Max-3C XRD diffractometer. The crystallinity was defined by the diffraction peak height of Y-type molecular sieve at 2θ = 22-24.5°.

[0036] The wear strength of the spray microspheres was determined by the gas generation method, according to the standard Q / SYLS 0518-2002, which is the standard of the Petrochemical Research Institute of China National Petroleum Corporation. Before the test, the spray microspheres were not calcined. The spray microspheres were placed in the MS-C type wear index analyzer, which is used to measure the wear index, and impacted with airflow for 5 hours. The amount of fine powder collected in the first hour was the amount contained in the microspheres during preparation. The amount of fine powder collected in the last 4 hours was taken as the amount of fine powder generated (less than 15 μm). The percentage of the mass of fine powder collected in the last 4 hours to the total mass of the sample was the wear index.

[0037] Pore ​​volume determination by water droplet method: Place approximately 80g of catalyst sample in an evaporating dish and ignite at 480℃ for 1 hour. Remove and cool in a desiccator. Add 20g of sample to an Erlenmeyer flask, accurate to 0.1g. Add distilled water to the Erlenmeyer flask through a burette. As water is added, the catalyst's fluidity decreases. Stir continuously with a glass rod until the sample loses its fluidity and all clumps together. Record the amount of water consumed. Calculate the pore volume using Vp = V / m. Vp - pore volume of sample, ml / g; V - volume of titrated water consumed, ml; m - sample mass, g.

[0038] Catalyst evaluation

[0039] Before evaluating the catalyst, it was subjected to heavy metal contamination. The method for simulating the nickel and vanadium content in industrial environments was as follows: An appropriate amount of analytical grade oxalic acid was dissolved in distilled water, stirred, and analytical grade ammonium metavanadate was slowly added. The mixture was heated and stirred until completely dissolved, cooled, and transferred to a volumetric flask to prepare a solution of a certain concentration. An aqueous solution of nickel nitrate (3000 ppm Ni, based on the dry weight of the catalyst) and a vanadium solution (5000 ppm V, based on the dry weight of the catalyst) were impregnated into the catalyst. After drying at 120°C, the catalyst was calcined at 550°C for 4 hours.

[0040] The reaction performance was evaluated using the ACE unit from Kayser Laboratories, USA. The feedstock used was from the 3 million tons / year heavy oil catalytic cracking unit of Lanzhou Petrochemical. The properties of the feedstock are shown in Table 1. The catalyst was aged at 800℃ and 100% steam for 17 hours before evaluation.

[0041] Table 1 Properties of feedstock oils used for catalyst selectivity assessment

[0042]

[0043]

[0044] Source of raw materials

[0045] The spent catalyst was used as a balancer in the catalytic cracking unit of Qingyang Petrochemical Company.

[0046] Water glass (SiO2 250g / l, Na2O 88g / l) was supplied by Lanzhou Petrochemical Catalyst Plant of China National Petroleum Corporation.

[0047] Sodium hydroxide, sodium carbonate, nickel nitrate, ammonium metavanadate, reagents from China National Pharmaceutical Group.

[0048] Aluminum sol (containing 20.58% Al2O3) and silica sol (containing 40% SiO2) were supplied by Lanzhou Petrochemical Catalyst Plant of China National Petroleum Corporation.

[0049] NaY zeolite directing agent (16Na2O:Al2O3:15SiO2:320H2O), produced by Lanzhou Petrochemical Company Catalyst Plant;

[0050] Kaolin, an industrial product of China Kaolin Corporation. Specific implementation examples:

[0052] Example 1

[0053] 400g of spent catalyst (dry basis, the same below) was weighed and mixed with 82.05g of sodium carbonate solid, and then ground using a ball mill to obtain spent catalyst with a median particle size D50 of 1.8μm. The ground spent catalyst, 2291.9g of kaolin, and 3% silica sol (based on the total mass of spent catalyst and kaolin) were added, along with deionized water to prepare a mixed slurry with a solid content of 41%. This slurry was then spray-dried to obtain kaolin spray microspheres with a median particle size D50 of 60-80μm. A portion of these microspheres was calcined at 990℃ for 1.2 hours to obtain kaolin microspheres GT-1.

[0054] 500g of GT-1 kaolin microspheres, 800ml of water glass, 689ml of 14wt% sodium hydroxide solution, and 96ml of directing agent were mixed and stirred for 15 minutes. The mixture was then transferred to a stainless steel reactor and heated to 95℃ for static crystallization for 28 hours. After crystallization, the white powder in the solution was removed by sedimentation washing. The solution was then filtered, washed, and dried to obtain NaY / kaolin composite microspheres CP-1. X-ray diffraction analysis showed that it contained 33% NaY zeolite.

[0055] In a stainless steel reactor, 500g of crystallization product, ammonium nitrate, ammonium chloride, and deionized water were added under stirring. The mass ratio of ammonium nitrate, ammonium chloride, and crystallization product was: ammonium nitrate / crystallization product = 0.3, ammonium chloride / crystallization product = 0.5. The mixture was exchanged for 1.1 hours at pH 3.3–3.8 and 65℃. The filtrate was removed by filtration, and the filter cake was washed with deionized water and dried to obtain a primary material. The primary material was then calcined at 609℃ with a steam flow rate of 40v% for 1.8 hours to obtain a secondary calcined material. This secondary calcined material was then exchanged once more with cerium chloride under the following conditions: RE₂O₃ / secondary calcined material = 0.06 (based on the mass of rare earth oxides), pH 3.8–4.2, temperature 78℃, and time 0.8 hours. The exchanged material was then filtered. The product was washed and dried to obtain a secondary calcined material. This secondary calcined material was then calcined at 500℃ for 1.3 hours with 20% steam permeation to obtain a secondary calcined material. The secondary calcined material was then exchanged with ammonium chloride at a mass ratio of ammonium chloride / secondary calcined material = 0.7, pH = 3.0–3.5, at 73℃ for 0.6 hours. The filtrate was removed by filtration, and the filter cake was washed with deionized water to obtain a tertiary calcined material. This tertiary calcined material was mixed with water and slurried at 55℃. Magnesium nitrate was added at a mass ratio of MgO / tertiary calcined material = 0.03 (based on the mass of alkaline earth oxides), and the pH was adjusted to 6.5. The mixture was stirred for 0.5 hours. The product was then filtered, washed with water, and dried to obtain catalyst CAT-1 with a Na₂O content of 0.31%, a rare earth oxide content of 4.25%, and a MgO content of 2.89%.

[0056] Example 2

[0057] 300g of spent catalyst was weighed and mixed with 27.1g of solid sodium hydroxide, then ground using a ball mill to obtain spent catalyst with a median particle size D50 of 1.4μm. The ground spent catalyst, 852.1g of kaolin, and 6% aluminum sol (based on the total mass of the spent catalyst and kaolin) were added to deionized water to prepare a mixed slurry with a solid content of 33%. This slurry was then spray-dried to obtain kaolin spray microspheres with a median particle size D50 of 60-80μm. A portion of these microspheres was calcined at 940℃ for 2.9 hours to obtain kaolin microspheres GT-2.

[0058] 600g of GT-2 kaolin microspheres, 1000ml of water glass, 749ml of 14wt% sodium hydroxide solution, and 138ml of directing agent were mixed and stirred for 30 minutes. The mixture was then transferred to a stainless steel reactor and heated to 99℃ for static crystallization for 30 hours. After crystallization, the white powder in the solution was removed by sedimentation washing, followed by filtration, washing, and drying of the filter cake to obtain NaY / kaolin composite microspheres CP-2. X-ray diffraction analysis showed that it contained 45% NaY zeolite.

[0059] 500g of crystallization product, ammonium sulfate, and deionized water were added to a stainless steel reactor under stirring. The mass ratio of ammonium sulfate to crystallization product was 0.8. The mixture was exchanged for 0.5 hours at pH 4.0–4.5 and 80℃. The filtrate was removed by filtration, and the filter cake was washed with deionized water and dried to obtain a primary material. The primary material was then calcined at 550℃ and 100% steam for 1.9 hours to obtain a secondary calcined material. This secondary calcined material was then exchanged once with lanthanum chloride under the following conditions: RE₂O₃ / secondary calcined material (based on the mass of rare earth oxides) = 0.04, pH 3.5–4.0, temperature 95℃, and time 1.2 hours. The exchanged material was then filtered, washed, and dried to obtain... The second-stage material was calcined at 650℃ for 2.3 hours with 10% steam to obtain the second-stage calcined material. The second-stage calcined material was then exchanged with ammonium nitrate at a mass ratio of ammonium nitrate / second-stage calcined material = 1.0, pH = 3.3-3.8, at 92℃ for 1.5 hours. The filtrate was removed by filtration, and the filter cake was washed with deionized water to obtain the third-stage material. The third-stage material was mixed with water and slurryed at 65℃. Cerium chloride was added at a mass ratio of RE2O3 / third-stage material = 0.04 based on rare earth oxides, and the pH was adjusted to 8.0. The mixture was stirred for 0.9 hours. The exchange product was filtered, washed with water, and dried to obtain catalyst CAT-2 with a Na2O content of 0.28% and a rare earth oxide content of 6.13%.

[0060] Example 3

[0061] 500g of spent catalyst was weighed and mixed with 85.5g of sodium carbonate solid, and then ground using a ball mill to obtain spent catalyst with a median particle size D50 of 0.8μm. The ground spent catalyst, 5908g of kaolin, 10% water glass (based on the total mass of spent catalyst and kaolin), and deionized water were added to prepare a mixed slurry with a solid content of 39%. This slurry was then spray-dried to obtain kaolin spray microspheres with a median particle size D50 of 60-80μm. A portion of these microspheres was calcined at 970℃ for 1.5 hours to obtain kaolin microspheres GT-3.

[0062] 400g of GT-3 kaolin microspheres, 328ml of water glass, 351ml of 14wt% sodium hydroxide solution, and 79ml of directing agent were mixed and stirred for 40 minutes. The mixture was then transferred to a stainless steel reactor and heated to 103℃ for static crystallization for 34 hours. After crystallization, the white powder in the solution was removed by sedimentation washing, followed by filtration, washing, and drying of the filter cake to obtain NaY / kaolin composite microspheres CP-3. X-ray diffraction analysis showed that it contained 37% NaY zeolite.

[0063] 400g of crystallized product, lanthanum nitrate, and deionized water were added to a stainless steel reactor under stirring. The ratio of RE₂O₃ / crystallized product (based on the mass of rare earth oxides) was 0.02. The mixture was exchanged for 1.6 hours at pH 3.5–4.0 and 77℃. The filtrate was removed by filtration, and the filter cake was washed with deionized water and dried to obtain a primary material. The primary material was then calcined at 700℃ with a steam flow rate of 20% for 1.4 hours to obtain a secondary calcined material. This secondary calcined material was then exchanged once more with ammonium sulfate, with a mass ratio of ammonium sulfate / primary calcined material of 0.6, at pH 3.0–3.3, a temperature of 83℃, and a time of 1.8 hours. The exchanged material was then filtered, washed, and dried to obtain a secondary material. The first exchange material was calcined at 530℃ for 2.0 hours under a steam flow rate of 50v% to obtain the second calcined material. The second calcined material was then exchanged with ammonium chloride at a mass ratio of ammonium chloride / second calcined material = 0.9, pH = 3.3-3.5, at 88℃ for 1.9 hours. The filtrate was removed by filtration, and the filter cake was washed with deionized water to obtain the third calcined material. The third calcined material was mixed with water and slurryed at 60℃. Lanthanum chloride was added at a mass ratio of RE2O3 / third calcined material = 0.023 based on rare earth oxides, and the pH was adjusted to 8.5. The mixture was stirred for 1.0 h. The exchange product was filtered, washed with water, and dried to obtain catalyst CAT-3 with a Na2O content of 0.47% and a rare earth oxide content of 3.49%.

[0064] Example 4

[0065] 400g of spent catalyst was weighed and mixed with 77.4g of solid sodium hydroxide, then ground using a ball mill to obtain spent catalyst with a median particle size D50 of 1.1μm. The ground spent catalyst, 1374.5g of kaolin, 2% water glass and 6% alumina sol (based on the total mass of spent catalyst and kaolin), and deionized water were added to prepare a mixed slurry with a solid content of 45%. This slurry was then spray-dried to obtain kaolin spray microspheres with a median particle size D50 of 60-80μm. A portion of these microspheres was calcined at 960℃ for 2.0 hours to obtain kaolin microspheres GT-4.

[0066] 550g of GT-3 kaolin microspheres, 475ml of water glass, 759ml of 14wt% sodium hydroxide solution, and 142ml of directing agent were mixed and stirred for 45 minutes. The mixture was then transferred to a stainless steel reactor and heated to 101℃ for static crystallization for 20 hours. After crystallization, the white powder in the solution was removed by sedimentation washing. The solution was then filtered, washed, and dried to obtain NaY / kaolin composite microspheres CP-4. X-ray diffraction analysis showed that it contained 42% NaY zeolite.

[0067] 600g of the above crystallized product, ammonium nitrate, and deionized water were added to a reactor under stirring. The mass ratio of ammonium nitrate to crystallized product was 1.2. The mixture was exchanged for 1.3 hours at 98°C and pH 3.0–3.5. The filtrate was removed by filtration, and the filter cake was washed and dried with deionized water to obtain a primary exchange material. The primary exchange material was then exchanged with cerium chloride at a ratio of RE₂O₃ / primary exchange material of 0.03 (based on the mass of rare earth oxides). The exchange was carried out at 92°C and pH 3.5–4.0 for 0.7 hours. The exchange product was filtered, washed with water, and dried to obtain a secondary exchange material. The secondary exchange material was calcined at 580°C and steam flow rate of 90% for 2.4 hours to obtain a primary calcined material. The primary calcined material was then exchanged once more with lanthanum nitrate and ammonium chloride under the following conditions: the mass ratio of ammonium chloride to primary calcined material was 0.40 (based on the mass of rare earth oxides). The first-stage material was calcined at 0.03%, pH 3.8–4.2, temperature 100℃, and time 1.2 hours. The calcined material was then filtered, washed, and dried to obtain the third-stage material. The third-stage material was calcined at 630℃ and 60% steam for 1.6 hours to obtain the second-stage material. The second-stage material was then exchanged with ammonium sulfate at a mass ratio of 0.9 (ammonium sulfate / second-stage material), pH 4.2–4.5, at 92℃ for 0.8 hours. The filtrate was removed by filtration, and the filter cake was washed with deionized water to obtain the third-stage material. The third-stage material was mixed with water and slurryed at 50℃. Lanthanum chloride was added at a mass ratio of 0.035 (RE2O3 / third-stage material) based on rare earth oxides, and the pH was adjusted to 7.0. The mixture was stirred for 0.8 hours. The exchange product was then filtered, washed with water, and dried to obtain catalyst CAT-4 with a Na2O content of 0.38% and a rare earth oxide content of 7.09%.

[0068] Example 5

[0069] 600g of spent catalyst was weighed and mixed with 38.7g of solid sodium hydroxide, then ground using a ball mill to obtain spent catalyst with a median particle size D50 of 1.6μm. The ground spent catalyst, 2932.7g of kaolin, and 2% silica sol and 3% alumina sol (based on the total mass of spent catalyst and kaolin) were added, along with deionized water to prepare a mixed slurry with a solid content of 36%. This slurry was then spray-dried to obtain kaolin spray microspheres with a median particle size D50 of 60-80μm. A portion of these microspheres was calcined at 980℃ for 2.2 hours to obtain kaolin microspheres GT-5.

[0070] 620g of GT-5 kaolin microspheres, 443ml of water glass, 926ml of 14wt% sodium hydroxide solution, and 173ml of a directing agent were mixed and stirred for 35 minutes. The mixture was then transferred to a stainless steel reactor and heated to 97℃ for static crystallization for 26 hours. After crystallization, the white powder in the solution was removed by sedimentation washing. The solution was then filtered, washed, and dried to obtain NaY / kaolin composite microspheres CP-5. X-ray diffraction analysis showed that it contained 39% NaY zeolite.

[0071] 500g of crystallization product, ammonium nitrate, and deionized water were added to a stainless steel reactor under stirring. The mass ratio of ammonium nitrate to crystallization product was 0.95. The mixture was exchanged at pH 3.5–3.8 and 88℃ for 1.3 hours. The filtrate was removed by filtration, and the filter cake was washed and dried with deionized water to obtain a primary material. The primary material was calcined at 580℃ under anhydrous conditions for 1.9 hours to obtain a secondary calcined material. The secondary calcined material was then exchanged once more with lanthanum nitrate. The mass ratio of RE₂O₃ to the primary calcined material was 0.05 (based on rare earth oxide mass), at pH 3.3–3.5, at 94℃ for 2.2 hours. The exchanged material was then filtered, washed, and dried to obtain a secondary material. The secondary material was then calcined at 64℃. The secondary calcined material was obtained by calcining at 0℃ and a steam flow rate of 100v% for 2.1 hours. The secondary calcined material was then exchanged with ammonium chloride at a mass ratio of ammonium chloride / secondary calcined material = 0.75, pH = 3.8-4.2, at 74℃ for 1.5 hours. The filtrate was removed by filtration, and the filter cake was washed with deionized water to obtain the tertiary calcined material. The tertiary calcined material was mixed with water and slurryed at 70℃. Cerium chloride was added at a mass ratio of RE2O3 / tertiary calcined material = 0.025 based on rare earth oxides, and the pH was adjusted to 7.5. The mixture was stirred for 1.5 hours. The exchange product was filtered, washed with water, and dried to obtain catalyst CAT-5 with a Na2O content of 0.36% and a rare earth oxide content of 5.28%.

[0072] Comparative Example 1

[0073] This comparative example uses kaolin instead of spent catalyst and prepares the catalyst in situ without grinding. 1774.5 g of kaolin and 77.4 g of sodium hydroxide solid were weighed, and 2% water glass and 6% aluminum sol (based on the total mass of kaolin) were added. Deionized water was then added to prepare a mixed slurry with a solid content of 45%. This slurry was then spray-dried to obtain kaolin spray microspheres with a median particle size D50 of 60-80 μm. A portion of these microspheres was calcined at 960℃ for 2.0 hours to obtain kaolin microspheres GT-6.

[0074] 550g of GT-6 kaolin microspheres, 475ml of water glass, 759ml of 14wt% sodium hydroxide solution, and 142ml of directing agent were mixed and stirred for 45 minutes. The mixture was then transferred to a stainless steel reactor and heated to 101℃ for static crystallization for 20 hours. After crystallization, the white powder in the solution was removed by sedimentation washing. The solution was then filtered, washed, and dried to obtain NaY / kaolin composite microspheres CP-4. X-ray diffraction analysis showed that it contained 22% NaY zeolite.

[0075] 600g of the above crystallized product, ammonium nitrate, and deionized water were added to a reactor under stirring. The mass ratio of ammonium nitrate to crystallized product was 1.2. The mixture was exchanged for 1.3 hours at 98°C and pH 3.0–3.5. The filtrate was removed by filtration, and the filter cake was washed and dried with deionized water to obtain a primary exchange material. The primary exchange material was then exchanged with cerium chloride at a ratio of RE₂O₃ / primary exchange material of 0.03 (based on the mass of rare earth oxides). The exchange was carried out at 92°C and pH 3.5–4.0 for 0.7 hours. The exchange product was filtered, washed with water, and dried to obtain a secondary exchange material. The secondary exchange material was calcined at 580°C and steam flow rate of 90% for 2.4 hours to obtain a primary calcined material. The primary calcined material was then exchanged once more with lanthanum nitrate and ammonium chloride under the following conditions: the mass ratio of ammonium chloride to primary calcined material was 0.40 (based on the mass of rare earth oxides). The first calcined material was prepared at a concentration of 0.03%, pH 3.8–4.2, temperature 100℃, and time 1.2 hours. The exchanged material was then filtered, washed, and dried to obtain the third calcined material. The third calcined material was then calcined at 630℃ and 60% steam for 1.6 hours to obtain the second calcined material. The second calcined material was then exchanged with ammonium sulfate at a mass ratio of 0.9 (ammonium sulfate / second calcined material = 0.9), pH 4.2–4.5, at 92℃ for 0.8 hours. The filtrate was removed by filtration, and the filter cake was washed with deionized water to obtain the third calcined material. The third calcined material was then mixed with water and slurryed at 50℃. Lanthanum chloride was added at a mass ratio of 0.035 (RE2O3 / third calcined material = 0.035), the pH was adjusted to 7.0, and the mixture was stirred for 0.8 hours. The exchanged product was then filtered, washed with water, and dried to obtain catalyst CAT-6 with a Na2O content of 0.43% and a rare earth oxide content of 7.13%.

[0076] Comparative Example 2

[0077] The comparative example waste catalyst was individually ground using a ball mill, yielding a waste catalyst with a median particle size D50 of 1.1 μm. 400 g of waste catalyst, 77.4 g of sodium hydroxide solid, and 1374.5 g of kaolin were weighed, and 2% water glass and 6% alumina sol (based on the total mass of the waste catalyst and kaolin) were added to deionized water to prepare a mixed slurry with a solid content of 45%. This slurry was then spray-dried to obtain kaolin spray microspheres. A portion of these microspheres was calcined at 960℃ for 2.0 hours to obtain kaolin microspheres GT-7.

[0078] 550g of GT-7 kaolin microspheres, 475ml of water glass, 759ml of 14wt% sodium hydroxide solution, and 142ml of directing agent were mixed and stirred for 45 minutes. The mixture was then transferred to a stainless steel reactor and heated to 101℃ for static crystallization for 20 hours. After crystallization, the white powder in the solution was removed by sedimentation washing. The solution was then filtered, washed, and dried to obtain NaY / kaolin composite microspheres CP-7. X-ray diffraction analysis showed that it contained 18% NaY zeolite.

[0079] 600g of the above crystallized product, ammonium nitrate, and deionized water were added to a reactor under stirring. The mass ratio of ammonium nitrate to crystallized product was 1.2. The mixture was exchanged for 1.3 hours at 98°C and pH 3.0–3.5. The filtrate was removed by filtration, and the filter cake was washed and dried with deionized water to obtain a primary exchange material. The primary exchange material was then exchanged with cerium chloride at a ratio of RE₂O₃ / primary exchange material of 0.03 (based on the mass of rare earth oxides). The exchange was carried out at 92°C and pH 3.5–4.0 for 0.7 hours. The exchange product was filtered, washed with water, and dried to obtain a secondary exchange material. The secondary exchange material was calcined at 580°C and steam flow rate of 90% for 2.4 hours to obtain a primary calcined material. The primary calcined material was then exchanged once more with lanthanum nitrate and ammonium chloride under the following conditions: the mass ratio of ammonium chloride to primary calcined material was 0.40 (based on the mass of rare earth oxides). The first-stage material was prepared by calcining at 0.03%, pH 3.8–4.2, temperature 100℃, and time 1.2 hours. The exchanged material was then filtered, washed, and dried to obtain the third-stage material. The third-stage material was calcined at 630℃ and 60% steam for 1.6 hours to obtain the second-stage material. The second-stage material was then exchanged with ammonium sulfate at a mass ratio of 0.9 (ammonium sulfate / second-stage material), pH 4.2–4.5, at 92℃ for 0.8 hours. The filtrate was removed by filtration, and the filter cake was washed with deionized water to obtain the third-stage material. The third-stage material was mixed with water and slurryed at 50℃. Lanthanum chloride was added at a mass ratio of 0.035 (RE2O3 / third-stage material) based on rare earth oxides, and the pH was adjusted to 7.0. The mixture was stirred for 0.8 hours. The exchanged product was then filtered, washed with water, and dried to obtain catalyst CAT-7 with a Na2O content of 0.41% and a rare earth oxide content of 7.02%.

[0080] Table 2 lists the wear index and pore volume of CP-1 to CP-5 prepared from the in-situ crystallization products of Examples 1 to 5 and CP-6 and CP-7 prepared from the in-situ crystallization products of Comparative Examples 1 and 2.

[0081] Table 2 Comparison of physicochemical properties of CP-1 to CP-7

[0082] project CAT-1 CAT-2 CAT-3 CAT-4 CAT-5 CAT-6 CAT-7 Wear index, ω% 1.0 0.7 1.5 1.3 1.1 3.3 3.6 <![CDATA[Pore volume, cm 3 g -1 > 0.50 0.47 0.48 0.49 0.51 0.37 0.35 Crystallinity, % 33 45 37 42 39 22 18

[0083] As shown in Table 2, the wear index and pore volume data of the catalyst prepared by the method of the present invention are better than those of the in-situ crystallized catalyst prepared by the comparative example.

[0084] The catalyst performance of CAT-4 prepared in Example 4, CAT-6 prepared in Comparative Example 1, and CAT-7 prepared in Comparative Example 2 was evaluated on an ACE device at a reaction temperature of 500°C and a reactant-to-oil mass ratio of 5.0. The results are listed in Table 3. As shown in Table 3, the in-situ crystallization catalyst prepared by the method of this invention, under conditions of 3000 ppm Ni and 5000 ppm V contamination, exhibits stronger heavy oil conversion capacity, higher gasoline yield, lower coke yield, and higher total liquid yield compared to the comparative catalyst, indicating that the catalyst has good vanadium resistance.

[0085] Table 3 Evaluation of the reaction performance of different catalysts

[0086]

[0087] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a vanadium-resistant catalytic cracking catalyst, characterized in that, Includes the following steps: S1, the waste catalyst is mixed and ground with alkali, then mixed with kaolin and binder, pulped, sprayed, and made into spray microspheres; S2, after the sprayed microspheres are calcined at high temperature to transform into high-kaolin balls, they are mixed with water, alkaline solution, silicon source and directing agent, and crystallized to obtain NaY / kaolin composite microspheres; S3, NaY / kaolin composite microspheres were exchanged with ammonium salts and rare earth compounds, calcined, and vanadium-resistant components were precipitated to obtain vanadium-resistant catalytic cracking catalyst. In step S3, the vanadium-resistant component is an alkaline earth metal and / or a rare earth metal.

2. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, In step S1, the alkali is sodium hydroxide and / or sodium carbonate, and the amount of alkali added is 2 to 20% of the mass of the waste catalyst, calculated as a metal oxide.

3. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 2, characterized in that, In step S1, the amount of alkali added, calculated as metal oxide, is 5-15% of the mass of the spent catalyst.

4. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, In step S1, the median particle size D50 of the ground waste catalyst is less than 2.0 μm.

5. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, In step S1, the solid content of the mixed slurry formed by grinding the waste catalyst and alkali and mixing it with kaolin is 30-50%.

6. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, In step S1, the particle size of the spray microspheres is 20–110 μm.

7. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, By mass, the content of spent catalyst in the spray microspheres is 5%-30%.

8. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, The kaolin is one or more of hard kaolin and soft kaolin, with a particle size of 2.5 to 3.5 μm, a crystalline kaolinite content of more than 80%, an iron oxide content of less than 1.7%, and a sum of sodium oxide and potassium oxide of less than 0.5%.

9. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, In step S2, the molar ratio of the directing agent is (14-16) SiO2:(0.7-1.3) Al2O3:(14-16) Na2O:(300-330) H2O.

10. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, In step S2, the high-temperature calcination conditions are calcination at 920–1000℃ for 1–3 hours.

11. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, In step S1, the amount of binder added is 2% to 10% of the total mass of the waste catalyst and kaolin.

12. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 11, characterized in that, The binder is one or more of sodium silicate, silica sol, alumina sol, and pseudoboehmite.

13. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, In step S3, the ammonium salt is one or more of ammonium sulfate, ammonium chloride, ammonium nitrate, and ammonium phosphate; the rare earth compound is one or more of rare earth chloride and rare earth nitrate.

14. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, In step S3, the ammonium salt is ammonium chloride and / or ammonium nitrate.

15. The method for preparing the vanadium-resistant catalytic cracking catalyst according to claim 1, characterized in that, In the vanadium-resistant component, the rare earth and alkaline earth metals, calculated as oxides, have a mass ratio of 0.02-0.07 to the vanadium-resistant catalytic cracking catalyst.

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