A method for preparing a reduced olefin type in-situ crystallization catalyst

Abstract

The application discloses a preparation method of an in-situ crystallization catalyst for reducing olefins, and comprises the following steps: S1, waste catalyst is mixed with alkali and ground, then mixed with kaolin, beaten, sprayed, and sprayed microspheres are prepared; S2, after the sprayed microspheres are respectively converted into metakaolin microspheres and high-kaolin microspheres through medium-temperature and high-temperature calcination, the metakaolin microspheres and the high-kaolin microspheres are mixed with water, lye, a silicon source and a directing agent, and crystallization is carried out, so that NaY / kaolin composite microspheres are obtained; and S3, the NaY / kaolin composite microspheres are exchanged with an ammonium salt and a rare earth compound, and calcination is carried out, so that an in-situ crystallization catalyst is obtained. In the method, the waste catalyst is ground with alkali, so that the waste catalyst is refined, and the silicon-aluminum source in the waste catalyst can be better activated, and the reaction activity is improved.

Description

Technical Field

[0001] This invention belongs to the field of catalytic cracking technology, specifically relating to a method for preparing an olefin-reducing in-situ crystallization catalyst. Background Technology

[0002] Fossil fuels still dominate the world's energy mix. As environmental concerns grow, stricter quality standards are being established for related fuels. my country's National VI B gasoline quality standard has been implemented ahead of schedule in some provinces and cities and will be fully implemented in 2023. Under this standard, gasoline olefins will be further reduced from 18% in National VI A to 15% %. Given the large proportion of catalytic gasoline in my country's overall gasoline mix, reducing the olefin content of catalytic gasoline is of great significance in the National VI B gasoline quality upgrade.

[0003] As one of the core technologies of catalytic cracking, catalysts are an effective means to achieve the olefin reduction function of catalytic cracking by optimizing the functional components of the catalyst.

[0004] CN02155601.6 discloses a high-yield diesel oil olefin-reducing cracking catalyst and its preparation method. The catalyst comprises 5–45 wt% phosphorus and rare earth-modified Y zeolite, 0.5–30 wt% one or more other zeolites, 0.5–70 wt% clay, and 1–65 wt% high-temperature resistant inorganic oxides. The resulting catalyst exhibits strong olefin-reducing ability, high diesel oil yield, low coke yield, and strong heavy oil cracking capability.

[0005] CN02146614.9 discloses a petroleum hydrocarbon cracking catalyst containing rare earth Y-type zeolite and its preparation method. The catalyst is characterized by the rare earth Y-type zeolite undergoing a gas-phase reaction with silicon tetrachloride. This catalyst can be used for heavy oil and olefin reduction, reducing the zeolite dosage by 5-25%.

[0006] CN201110332264.3 discloses an alkali- and nitrogen-resistant olefin-reducing cracking catalyst and its preparation method. The catalyst comprises a cracking active component, a mesoporous silica-alumina material, a binder, and clay. The cracking active component includes a first Y-type molecular sieve and a second Y-type molecular sieve. The first Y-type molecular sieve is modified with multiple elements including rare earth, iron, copper, and phosphorus, while the second Y-type molecular sieve is modified with phosphorus and rare earth elements. This catalyst is used for the catalytic cracking of hydrocarbon oils with high alkali and nitrogen content, exhibiting higher conversion rates and lower gasoline olefin content.

[0007] In catalytic cracking, the reduction of olefins in catalytic gasoline is mainly achieved by enhancing the hydrogen transfer reaction. The hydrogen transfer reaction is a bimolecular reaction, requiring a high acid density at the active sites. The main active component of the catalytic cracking catalyst is a Y-type molecular sieve. The aforementioned patented olefin-reducing catalyst is primarily a semi-synthetic catalyst. Its olefin-reducing function is achieved through composite modification of the Y-type molecular sieve, improving its stability and increasing the acid site density. Since the Y-type molecular sieve is the main active component, further enhancing its olefin-reducing ability often requires increasing its content, leading to increased catalyst costs.

[0008] In-situ crystallization catalysts have the characteristic of forming molecular sieves and matrix simultaneously. By optimizing the preparation conditions, increasing the Y-type molecular sieve content of the in-situ crystallization catalyst has little impact on the cost of the catalyst.

[0009] CN1778676A proposes a method for synthesizing high-content NaY molecular sieves from kaolin spray microspheres. One or more of starch, graphite powder, and carboxymethyl cellulose are added as structural additives to the spray microspheres to improve their structure. After crystallization, high-content NaY molecular sieves are obtained. However, the structural additives need to be removed by calcination, increasing carbon emissions during catalyst production.

[0010] The in-situ crystallization catalyst synthesized in US4493902, 6656347, 6696378, 6942783, 6943132, and CN 01817891.X has macropores ranging from 60 nm to 2000 nm and a high molecular sieve content. However, the technology has very high requirements for the raw materials used in spray molding. In order to stack more macropores, the importance of ultrafine raw clay and ultrafine high-density clay is emphasized. However, such clay is expensive and not easy to purchase on the market. At the same time, silicon retention technology is also adopted to increase the strength of the catalyst.

[0011] Yi Huihua et al. (China Nonmetallic Minerals Industry Guide, 2009, 74, 33-36) synthesized an in-situ crystallized product with high molecular weight sieve content using Hainan coconut shell powder as a pore-expanding agent. The addition of the pore-expanding agent also resulted in a product with more macropores. However, this method requires the coconut shell powder to undergo desalting with sulfuric acid and phosphoric acid, desiliconizing with potassium hydroxide, and activation treatment at 500-600℃, making the process complex and unsuitable for industrial production.

[0012] CN201210061876.8 discloses a method for preparing a catalytic cracking co-catalyst. This method involves introducing a compound with a boiling point of 150°C or less, or one that decomposes completely into a gas at 150°C, into a kaolin spray slurry. This increases the content of Y-type molecular sieves in the in-situ crystallization catalyst and introduces abundant mesoporous and macroporous structures. However, this compound is easily released into the atmosphere during the spray drying process, causing air pollution.

[0013] CN201010262279.2 discloses a method for preparing NaY zeolite, which improves the pore structure of kaolin microspheres by introducing polydimethyldiallyl ammonium chloride, thereby obtaining a highly crystalline product. However, the high-temperature calcination removal of polydimethyldiallyl ammonium chloride also poses environmental pollution problems.

[0014] Therefore, simple, environmentally friendly, and low-cost methods for increasing the molecular sieve content of in-situ crystallization catalysts still need further development.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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, further development is needed to refine methods for preparing catalysts with strong olefin-reducing properties by utilizing spent catalytic cracking catalysts to increase the content of in-situ crystallized Y-type molecular sieves. Summary of the Invention

[0020] The purpose of this invention is to provide a method for preparing an olefin-reducing in-situ crystallization catalyst. The in-situ crystallization catalyst prepared by this method has higher crystallinity of Y-type molecular sieves, higher gasoline yield and lower gasoline olefin content in the cracking reaction.

[0021] To achieve the above objectives, the present invention provides a method for preparing the aforementioned olefin-reducing in-situ crystallization catalyst, comprising the following steps:

[0022] S1, the waste catalyst is mixed and ground with alkali, then mixed with kaolin, pulped, sprayed, and made into spray microspheres;

[0023] S2, after being calcined at medium and high temperatures to transform into kaolin balls and high-kaolin balls respectively, the sprayed microspheres were mixed with water, alkaline solution, silicon source and directing agent, and crystallized to obtain NaY / kaolin composite microspheres;

[0024] S3, NaY / kaolin composite microspheres were subjected to ammonium salt and rare earth compound exchange and calcination to obtain an in-situ crystallized catalyst.

[0025] The preparation method of the olefin-reducing in-situ crystallization 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 metal oxide, is 2 to 20% of the mass of the waste catalyst, preferably 5 to 15%.

[0026] In the preparation method of the olefin-reducing in-situ crystallization 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.

[0027] In the preparation method of the olefin-reducing in-situ crystallization 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%.

[0028] In the preparation method of the olefin-reducing in-situ crystallization catalyst of the present invention, in step S1, the particle size of the spray microspheres is 20-110 μm.

[0029] The preparation method of the olefin-reducing in-situ crystallization catalyst of the present invention, by mass, has a waste catalyst content of 5%-30% in the spray microspheres.

[0030] The method for preparing the olefin-reducing in-situ crystallization catalyst of the present invention comprises the following: the kaolin 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%, an iron oxide content of less than 1.7%, and a sum of sodium oxide and potassium oxide of less than 0.5%.

[0031] In the preparation method of the olefin-reducing in-situ crystallization catalyst of the present invention, the alkaline solution and its amount added in step S2 are known to those skilled in the art, and sodium hydroxide is preferred. No particular limitation is made 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.

[0032] In the preparation method of the olefin-reducing in-situ crystallization catalyst of the present invention, the mass ratio of high-density soil ball to low-density soil ball in step S2 is 3:1 to 1:2.

[0033] In the preparation method of the olefin-reducing in-situ crystallization catalyst of the present invention, in step S2, the calcination conditions of the spray microspheres are: calcination at 920-1000℃ for 1-3 hours to obtain high-earth microspheres; and calcination at 600-900℃ for 1-3 hours to obtain low-earth microspheres.

[0034] In the preparation method of the olefin-reducing in-situ crystallization catalyst of the present invention, in step S1, when the waste catalyst and kaolin are slurried, a binder is added, and the amount of binder added is 2% to 10% of the total mass of the waste catalyst and kaolin.

[0035] The preparation method of the olefin-reducing in-situ crystallization 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.

[0036] In the preparation method of the olefin-reducing in-situ crystallization 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.

[0037] The method for preparing the olefin-reducing in-situ crystallization catalyst of the present invention, wherein the rare earth element in the in-situ crystallization catalyst is calculated as rare earth oxide, and the mass ratio of rare earth to catalyst is 0.04-0.1.

[0038] In this invention, the exchange and calcination 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 of this invention are: exchange at pH = 3–6 and temperature 60–100℃; calcination temperature 500–800℃, time 0.5–2 hours, and steam content 0–100%.

[0039] Beneficial effects of this invention:

[0040] This invention involves mixing and grinding spent catalyst, followed by mixing and slurrying with kaolin to prepare spray microspheres, which are then further crystallized in situ to obtain NaY / kaolin composite microspheres. The spent catalyst is ground with alkali, which not only refines the spent catalyst but also better activates the silicon-aluminum source within it, 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 can act as a structure guide 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 in-situ crystallized catalyst prepared using this invention exhibits higher Y-type molecular sieve crystallinity, higher pore volume, and stronger olefin-reducing ability in cracking reactions. Detailed Implementation

[0041] 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.

[0042] Analytical methods

[0043] 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°.

[0044] 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.

[0045] 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.

[0046] Evaluation methods

[0047] The reaction performance was evaluated using a riser unit. The feedstock used was from the 3 million tons / year heavy oil catalytic cracking unit of Lanzhou Petrochemical, and its properties are shown in Table 1. The catalyst was aged at 800℃ with 100% steam for 10 hours before evaluation.

[0048] Table 1 Properties of feedstock oils used for catalyst selectivity assessment

[0049]

[0050] Source of raw materials

[0051] The spent catalyst was used as a balancer in the catalytic cracking unit of Qingyang Petrochemical Company.

[0052] Water glass (SiO2 250g / l, Na2O 88g / l) was supplied by Lanzhou Petrochemical Catalyst Plant of China National Petroleum Corporation.

[0053] Sodium hydroxide, sodium carbonate, reagents from China National Pharmaceutical Group;

[0054] Aluminum sol (containing 20.58% Al2O3) and silica sol (containing 40% SiO2) were supplied by Lanzhou Petrochemical Catalyst Plant of China National Petroleum Corporation.

[0055] NaY zeolite directing agent (16Na2O:Al2O3:15SiO2:320H2O), produced by Lanzhou Petrochemical Company Catalyst Plant;

[0056] Kaolin, an industrial product of China Kaolin Corporation. Specific implementation examples:

[0058] Example 1

[0059] 500g of spent catalyst (dry basis, the same below) was weighed and mixed with 38.7g of sodium hydroxide solid, and then ground using a ball mill to obtain spent catalyst with a median particle size D50 of 1.7μm. The ground spent catalyst, 1565.7g of kaolin, and 7% aluminum 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 43%. 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 950℃ for 2.7 hours to obtain kaolin microspheres GT-1, and another portion was calcined at 850℃ for 2.0 hours to obtain kaolin microspheres PT-1.

[0060] 500g of GT-1 kaolin microspheres and 400g of PT-1 kaolin microspheres were mixed with 1750ml of water glass, 600ml of 14wt% sodium hydroxide solution, and 380ml of a directing agent. After stirring for 30 minutes, the mixture was transferred to a stainless steel reactor and heated to 91℃ for static crystallization for 32 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-1. X-ray diffraction analysis showed that it contained 46% NaY zeolite.

[0061] 500g of crystallization product, ammonium chloride, and deionized water were added to a stainless steel reactor under stirring. The mass ratio of ammonium chloride to crystallization product was 0.6. The mixture was exchanged at pH 3.5–3.8 and 70℃ for 2.1 hours. The filtrate was removed by filtration, and the filter cake was washed with deionized water and dried to obtain a primary material. This primary material was then calcined at 510℃ with a steam flow rate of 70% for 2.2 hours to obtain a secondary calcined material. This secondary calcined material was then exchanged once more with lanthanum nitrate under the following conditions: RE₂O₃ - calcined material = 0.04 (based on the mass of rare earth oxides), pH 3.5–3.8, and 70℃. =4.0~4.5, temperature is 90℃, time is 0.9 hours, the exchanged material is filtered, washed and dried to obtain secondary exchange material; the secondary exchange material is calcined at 610℃ and steam flow rate is 80v% for 1.5 hours to obtain secondary calcined material; the secondary calcined material is exchanged with cerium chloride, based on the mass of rare earth oxides, RE2O3 / primary calcined material = 0.04, pH = 3.5~4.0, exchanged at 82℃ for 1.3 hours, the product is filtered, washed with water and dried to obtain catalyst CAT-1 with Na2O content of 0.45% and rare earth oxide content of 6.97%.

[0062] Example 2

[0063] 600g of spent catalyst was weighed and mixed with 85.2g of sodium hydroxide solid, and then ground using a ball mill to obtain spent catalyst with a median particle size D50 of 1.2μm. The ground spent catalyst, 3668.9g of kaolin, 2% water glass and 4% silica sol (based on the total mass of spent catalyst and kaolin), were added to deionized water to prepare a mixed slurry with a solid content of 37%. 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 1.9 hours to obtain kaolin microspheres GT-2, and another portion was calcined at 680℃ for 1.7 hours to obtain kaolin microspheres PT-2.

[0064] 700g of GT-2 kaolin microspheres and 400g of PT-2 kaolin microspheres were mixed with 2470ml of water glass, 670ml of 14wt% sodium hydroxide solution, and 450ml of a directing agent. After stirring for 40 minutes, the mixture was transferred to a stainless steel reactor and heated to 105℃ for static crystallization for 24 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 43% NaY zeolite.

[0065] 500g of crystallization product, cerium chloride, and deionized water were added to a stainless steel reactor under stirring. The ratio of RE₂O₃ to crystallization product (based on the mass of rare earth oxides) was 0.1. The mixture was exchanged at pH 3.8–4.2 and 75°C for 1.3 hours. The filtrate was removed by filtration, and the filter cake was washed with deionized water and dried to obtain a primary material. This primary material was then calcined at 650°C with 60% steam for 1.8 hours to obtain a secondary calcined material. This secondary calcined material was then exchanged once more with ammonium sulfate, with the mass ratio of ammonium sulfate to crystallization product being ammonium sulfate / secondary calcined material = 0.8, at pH 3.3–3. The material was exchanged at 95℃ for 0.8 hours. After filtration, washing, and drying, the material was used to obtain the second-stage material. The second-stage material was then calcined at 550℃ for 2.5 hours with 85% 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 = 0.75, pH = 3.0-3.5, at 90℃ for 0.5 hours. The exchange product was then filtered, washed, and dried to obtain catalyst CAT-2 with a Na2O content of 0.29% and a rare earth oxide content of 8.19%.

[0066] Example 3

[0067] 400g of spent catalyst was weighed and mixed with 61.5g of sodium carbonate solid, and then ground using a ball mill to obtain spent catalyst with a median particle size D50 of 1.4μm. The ground spent catalyst, 4392.9g of kaolin, 3% aluminum sol (based on the total mass of spent catalyst and kaolin), and deionized water were mixed to prepare a slurry with a solid content of 32%. 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 3.0 hours to obtain kaolin microspheres GT-3, and another portion was calcined at 730℃ for 2.4 hours to obtain kaolin microspheres PT-3.

[0068] 600g of GT-3 kaolin microspheres and 700g of PT-3 kaolin microspheres were mixed, then mixed with 2938ml of water glass, 784ml of 14wt% sodium hydroxide solution, and 481ml of a directing agent. After stirring for 39 minutes, the mixture was transferred to a stainless steel reactor and heated to 94℃ 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-3. X-ray diffraction analysis showed that it contained 50% NaY zeolite.

[0069] 600g of the crystallized product prepared in Example 3, lanthanum chloride, 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 0.06. The mixture was exchanged for 1.1 hours at pH 3.3–4.8 and 85°C. The filtrate was removed by filtration, and the filter cake was washed with deionized water and dried to obtain a primary material. This primary material was then calcined at 620°C with a steam flow rate of 50% for 1.7 hours to obtain a calcined material. This calcined material was then exchanged once more with cerium nitrate under the following conditions: the ratio of RE₂O₃ / calcined material (based on the mass of rare earth oxides) was 0. The exchange process was carried out at 0.06°C, pH 4.0–4.5, temperature 93°C, and time 0.6 hours. The exchanged material was filtered, washed, and dried to obtain a secondary exchange material. The secondary exchange material was then calcined at 530°C with a steam flow rate of 55% for 2.1 hours to obtain a secondary calcined material. The secondary calcined material was then exchanged with ammonium nitrate at a mass ratio of ammonium nitrate / secondary calcined material = 0.5, pH 3.1–3.6, and at 96°C for 2.0 hours. The exchange product was filtered, washed, and dried to obtain catalyst CAT-3 with a Na2O content of 0.44% and a rare earth oxide content of 9.45%.

[0070] Example 4

[0071] 500g of spent catalyst was weighed and mixed with 90.3g of sodium hydroxide solid, and then ground using a ball mill to obtain spent catalyst with a median particle size D50 of 0.9μm. The ground spent catalyst, 2210.7g of kaolin, and 5% water glass (based on the total mass of the spent catalyst and kaolin) were added, along with deionized water to prepare a mixed slurry with a solid content of 40%. 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 930℃ for 1.5 hours to obtain kaolin microspheres GT-4, and another portion was calcined at 820℃ for 2.8 hours to obtain kaolin microspheres PT-4.

[0072] 700g of GT-3 kaolin microspheres, 500g of PT-3 kaolin microspheres, 2538ml of water glass, 824ml of 14wt% sodium hydroxide solution, and 465ml of directing agent were mixed and stirred for 50 minutes. The mixture was then transferred to a stainless steel reactor and heated to 97℃ 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-4. X-ray diffraction analysis showed that it contained 48% NaY zeolite.

[0073] 700g of the above crystallized product, ammonium sulfate, and deionized water were added to a reactor under stirring. The mass ratio of ammonium sulfate to crystallized product was 1.0. The mixture was exchanged at pH 3.5–4.0 and 88°C for 1.6 hours. The filtrate was removed by filtration, and the filter cake was washed with deionized water and dried to obtain a primary exchange material. The primary exchange material was then exchanged with lanthanum chloride at a ratio of RE₂O₃ / primary exchange material of 0.07 (based on the mass of rare earth oxides). The exchange was carried out at pH 3.0–3.5 and 80°C for 0.6 hours. The exchange product was filtered, washed with water, and dried to obtain a secondary exchange material. The secondary exchange material was then calcined at 630°C with a steam flow rate of 75% for 1.3 hours to obtain a primary calcined material. The first batch of material was exchanged once with ammonium chloride under the following conditions: ammonium chloride / first batch = 0.60 by mass, pH = 4.0-4.5, temperature = 97℃, and time = 1.0 hour. The exchanged material was filtered, washed, and dried to obtain the third batch. The third batch was calcined at 720℃ under anhydrous conditions for 2.0 hours to obtain the second batch. The second batch was then exchanged with ammonium nitrate at a mass ratio of ammonium nitrate / second batch = 0.7, pH = 4.5-4.8, and exchanged at 68℃ for 2.2 hours. The exchange product was filtered, washed, and dried to obtain catalyst CAT-4 with a Na2O content of 0.38% and a rare earth oxide content of 4.58%.

[0074] Example 5

[0075] 700g of spent catalyst was weighed and mixed with 117.4g of sodium hydroxide solid, and then ground using a ball mill to obtain spent catalyst with a median particle size D50 of 1.9μm. The ground spent catalyst, 2531.9g of kaolin, 2% silica sol and 8% alumina sol (based on the total mass of kaolin) were added, along with deionized water to prepare a mixed slurry with a solid content of 34%. 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 2.3 hours to obtain kaolin microspheres GT-5, and another portion was calcined at 800℃ for 1.4 hours to obtain kaolin microspheres PT-5.

[0076] 500g of GT-5 kaolin microspheres and 700g of PT-5 kaolin microspheres were mixed, then mixed with 2671ml of water glass, 769ml of 14wt% sodium hydroxide solution, and 490ml of a directing agent. After stirring for 45 minutes, the mixture was transferred to a stainless steel reactor and heated to 102℃ for static crystallization for 20 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-5. X-ray diffraction analysis showed that it contained 57% NaY zeolite.

[0077] 500g of crystallization product, ammonium nitrate, cerium chloride, and deionized water were added to a stainless steel reactor under stirring. The mass ratio of ammonium nitrate to crystallization product was 0.75, and the mass ratio of RE₂O₃ to crystallization product was 0.05 (based on the mass of rare earth oxides). The mixture was exchanged at pH 3.0–3.5 and 89℃ for 1.7 hours. The filtrate was removed by filtration, and the filter cake was washed with deionized water and dried to obtain a primary material. This primary material was then calcined at 500℃ with 100% steam flow for 2.3 hours to obtain a secondary calcined material. This secondary calcined material was then exchanged once more with ammonium chloride, with an ammonium chloride / secondary calcined material ratio of 0.45. The exchange process was carried out at a temperature of 65℃ and a pH of 3.8–4.2 for 1.2 hours. The exchanged material was then filtered, washed, and dried to obtain a secondary exchange material. The secondary exchange material was then calcined at 670℃ for 1.9 hours to obtain a secondary calcined material. The secondary calcined material was then exchanged with lanthanum nitrate. Based on the mass of rare earth oxides, the ratio of RE2O3 to secondary calcined material was 0.04. The pH was 3.5–4.0. After 0.9 hours of exchange at 84℃, the exchange product was filtered, washed, and dried to obtain catalyst CAT-5 with a Na2O content of 0.31% and a rare earth oxide content of 5.82%.

[0078] Comparative Example 1

[0079] In this comparative example, kaolin was used instead of spent catalyst, and the in-situ crystallization catalyst was prepared without grinding. 4792.9 g of kaolin, 61.5 g of sodium carbonate solid, 3% aluminum sol (based on the total mass of kaolin), and deionized water were weighed to prepare a mixed slurry with a solid content of 32%. This slurry was then spray-dried to obtain kaolin spray microspheres. A portion of these microspheres was calcined at 960℃ for 3.0 hours to obtain kaolin microspheres GT-6 with a median particle size D50 of 60-80 μm. Another portion was calcined at 730℃ for 2.4 hours to obtain kaolin microspheres PT-6.

[0080] 600g of GT-6 kaolin microspheres and 700g of PT-6 kaolin microspheres were mixed, then mixed with 2938ml of water glass, 784ml of 14wt% sodium hydroxide solution, and 481ml of a directing agent. After stirring for 39 minutes, the mixture was transferred to a stainless steel reactor and heated to 94℃ 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-6. X-ray diffraction analysis showed that it contained 33% NaY zeolite.

[0081] In a stainless steel autoclave, 600g of the crystallized product prepared in Comparative Example 1, lanthanum chloride, and deionized water were added with stirring. The ratio of RE₂O₃ / crystallized product (based on the mass of rare earth oxides) was 0.06. The mixture was exchanged for 1.1 hours at pH 3.3–4.8 and 85°C. The filtrate was removed by filtration, and the filter cake was washed with deionized water and dried to obtain a primary material. This primary material was then calcined at 620°C with a steam flow rate of 50% for 1.7 hours to obtain a calcined material. This calcined material was then exchanged once more with cerium nitrate under the following conditions: the ratio of RE₂O₃ / calcined material (based on the mass of rare earth oxides) was 0. The exchange process was carried out at 0.06°C, pH 4.0–4.5, temperature 93°C, and time 0.6 hours. The exchanged material was filtered, washed, and dried to obtain a secondary exchange material. The secondary exchange material was then calcined at 530°C with a steam flow rate of 55% for 2.1 hours to obtain a secondary calcined material. The secondary calcined material was then exchanged with ammonium nitrate at a mass ratio of ammonium nitrate / secondary calcined material = 0.5, pH 3.1–3.6, and at 96°C for 2.0 hours. The exchange product was filtered, washed, and dried to obtain catalyst CAT-6 with a Na2O content of 0.42% and a rare earth oxide content of 9.51%.

[0082] Comparative Example 2

[0083] The comparative example waste catalyst was individually ground using a ball mill, yielding a waste catalyst with a median particle size D50 of 1.2 μm. 600 g of the ground waste catalyst, 85.2 g of sodium hydroxide solid, and 3668.9 g of kaolin were weighed, along with 2% water glass and 4% silica sol (based on the total mass of the waste catalyst and kaolin). Deionized water was added to prepare a mixed slurry with a solid content of 37%. 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 970℃ for 1.9 hours to obtain kaolin microspheres GT-7, and another portion was calcined at 680℃ for 1.7 hours to obtain kaolin microspheres PT-7.

[0084] 700g of GT-7 kaolin microspheres and 400g of PT-7 kaolin microspheres were mixed with 2470ml of water glass, 670ml of 14wt% sodium hydroxide solution, and 450ml of a directing agent. After stirring for 40 minutes, the mixture was transferred to a stainless steel reactor and heated to 105℃ for static crystallization for 24 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-7. X-ray diffraction analysis showed that it contained 23% NaY zeolite.

[0085] In a stainless steel reactor, 500g of the crystallized product from Comparative Example 2, cerium chloride, and deionized water were added with stirring. The ratio of RE₂O₃ to crystallized product (based on the mass of rare earth oxides) was 0.1. The mixture was exchanged for 1.3 hours at pH 3.8–4.2 and 75°C. The filtrate was removed by filtration, and the filter cake was washed with deionized water and dried to obtain a primary material. This primary material was then calcined at 650°C with 60% steam for 1.8 hours to obtain a secondary calcined material. This secondary calcined material was then exchanged once more with ammonium sulfate. The mass ratio of ammonium sulfate to crystallized product was ammonium sulfate / secondary calcined material = 0.8, and the pH was 3.3. The material was exchanged at 95℃ for 0.8 hours, and then filtered, washed, and dried to obtain a secondary exchange material. The secondary exchange material was then calcined at 550℃ with 85% steam for 2.5 hours to obtain a secondary calcined material. The secondary calcined material was then exchanged with ammonium nitrate at a mass ratio of ammonium nitrate / secondary calcined material = 0.75, pH = 3.0-3.5, at 90℃ for 0.5 hours. The exchange product was then filtered, washed, and dried to obtain catalyst CAT-7 with a Na2O content of 0.28% and a rare earth oxide content of 8.22%.

[0086] 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.

[0087] Table 2 Comparison of physicochemical properties of CP-1 to CP-7

[0088] project CAT-1 CAT-2 CAT-3 CAT-4 CAT-5 CAT-6 CAT-7 Wear index, ω% 0.9 1.2 1.6 1.1 1.5 3.5 3.8 <![CDATA[Pore volume, cm 3 g -1 > 0.47 0.44 0.49 0.46 0.48 0.40 0.35 Crystallinity, % 46 43 50 48 57 33 23

[0089] 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.

[0090] The catalyst performance of CAT-3 prepared in Example 3 and CAT-6 prepared in Comparative Example 1, and CAT-2 prepared in Example 2 and CAT-7 prepared in Comparative Example 2 were evaluated on a riser device. The reaction temperature was 505°C, and the mass ratio of reactant to oil was 6.5. The results are listed in Table 3. As shown in Table 3, the in-situ crystallization catalyst prepared by the method of the present invention has a stronger heavy oil conversion capacity and a higher gasoline yield compared with the comparative catalyst.

[0091] Table 3 Evaluation of the reaction performance of different catalysts

[0092]

[0093] Table 4. Composition and property analysis of gasoline reacted with different catalysts.

[0094] project CAT-6 CAT-3 Difference CAT-7 CAT-2 Difference Cycloalkanes, v% 8.29 8.44 +0.15 8.21 8.48 +0.27 n-Alkanes, v% 4.40 4.54 +0.14 4.38 4.59 +0.21 Isoalkanes, v% 25.53 28.06 +2.53 24.23 29.31 +5.08 Olefins, v% 41.78 37.93 -3.85 43.96 35.88 -8.08 Aromatics, v% 20.00 21.03 +1.03 19.22 21.74 +2.52 MON 83.8 83.9 +0.1 83.9 83.6 -0.3 RON 94.1 94.1 0 94.2 93.8 -0.4

[0095] As shown in Table 4, compared with the comparative catalyst CAT-6, the in-situ crystallization catalyst CAT-3 prepared by the present invention reduced the olefin content of catalytic gasoline by 3.85 volume percentage points. At the same time, while the olefin content decreased, the RON content was comparable to that of the comparative catalyst. Compared with the comparative catalyst CAT-7, the in-situ crystallization catalyst CAT-2 prepared by the present invention reduced the olefin content of catalytic gasoline by 8.08 volume percentage points. While the olefin content decreased significantly, the RON content decreased by only 0.4 units.

[0096] 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 an olefin-reducing in-situ crystallization catalyst, characterized in that, Includes the following steps: S1, the waste catalyst is mixed and ground with sodium hydroxide or sodium carbonate, then mixed with kaolin, slurried, sprayed, and made into spray microspheres; S2, after being calcined at medium and high temperatures to transform into kaolin balls and high-kaolin balls respectively, the sprayed microspheres were 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 and then calcined to obtain an in-situ crystallized catalyst; In step S1, sodium hydroxide or sodium carbonate, calculated as a metal oxide, is added in an amount of 5-15% of the mass of the spent catalyst. By mass, the content of spent catalyst in the spray microspheres is 5%-30%; The median particle size D50 of the ground waste catalyst is less than 2.0 μm.

2. The method for preparing the olefin-reducing in-situ crystallization catalyst according to claim 1, characterized in that, In step S1, the solid content of the mixed slurry formed by grinding the waste catalyst with sodium hydroxide or sodium carbonate and then mixing it with kaolin is 30-50%.

3. The method for preparing the olefin-reducing in-situ crystallization catalyst according to claim 1, characterized in that, In step S1, the particle size of the spray microspheres is 20–110 μm.

4. The method for preparing the olefin-reducing in-situ crystallization 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%.

5. The method for preparing the olefin-reducing in-situ crystallization 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.

6. The method for preparing the olefin-reducing in-situ crystallization catalyst according to claim 1, characterized in that, In step S2, the mass ratio of the high soil ball to the partial soil ball is 3:1 to 1:

2.

7. The method for preparing the olefin-reducing in-situ crystallization catalyst according to claim 1, characterized in that, In step S2, the calcination conditions for the spray microspheres are: calcination at 920–1000℃ for 1–3 hours to obtain high-quality soil balls; and calcination at 600–900℃ for 1–3 hours to obtain partial-quality soil balls.

8. The method for preparing the olefin-reducing in-situ crystallization catalyst according to claim 1, characterized in that, In step S1, when the waste catalyst and kaolin are slurried, a binder is also added. The amount of binder added is 2% to 10% of the total mass of the waste catalyst and kaolin.

9. The method for preparing the olefin-reducing in-situ crystallization catalyst according to claim 8, characterized in that, The binder is one or more of sodium silicate, silica sol, alumina sol, or boehmite.

10. The method for preparing the olefin-reducing in-situ crystallization 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.

11. The method for preparing the olefin-reducing in-situ crystallization catalyst according to claim 1, characterized in that, In step S3, the ammonium salt is ammonium chloride and / or ammonium nitrate.

12. The method for preparing the olefin-reducing in-situ crystallization catalyst according to claim 1, characterized in that, In the in-situ crystallization catalyst, the rare earth elements are calculated as rare earth oxides, and the mass ratio of rare earth to catalyst is 0.04-0.1.

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