Naphtha light hydrocarbon catalytic cracking catalyst and preparation method thereof

Abstract

The invention provides a naphtha light hydrocarbon catalytic cracking catalyst. The naphtha light hydrocarbon catalytic cracking catalyst comprises a modified ZSM-5 molecular sieve, a Y-type molecular sieve, an inorganic oxide binder and clay, the preparation method of the modified ZSM-5 molecular sieve comprises the following steps: in a stirring state, adding a pore channel blocking agent with the particle size of less than 2nm into mixed slurry of a ZSM-5 molecular sieve and deionized water, then adding magnesium hydroxide colloid, drying, heating to 400-600 DEG C within 2-10 hours, and roasting to decompose the pore channel blocking agent, so as to obtain the modified ZSM-5 molecular sieve. According to the catalyst, magnesium hydroxide colloid and the ZSM-5 molecular sieve are combined, so that the catalyst can realize efficient acidic and alkaline catalysis in a system, the Y-type molecular sieve, the inorganic oxide binder, the clay and other components are combined and introduced, efficient acid-base catalysis can be realized in the naphtha light hydrocarbon catalytic cracking process, and the overall catalytic efficiency is improved; and the method is particularly beneficial for increasing the yield of propylene and other light olefins.

Description

Technical Field

[0001] This invention belongs to the field of petroleum catalytic cracking, specifically relating to a naphtha light hydrocarbon catalytic cracking catalyst and its preparation method. Background Technology

[0002] With the rapid development of the global economy, the petrochemical industry is also experiencing a period of rapid growth. In recent years, the rapid increase in demand for propylene derivatives, especially polypropylene, has led to a sharp increase in global propylene demand. Traditional steam cracking to olefins methods suffer from drawbacks such as high reaction temperatures, narrow feedstock sources, and difficulty in flexibly adjusting product distribution. Similarly, catalytic cracking to increase olefin production also has limitations, such as producing mainly gasoline and diesel and low olefin yields. Naphtha catalytic cracking technology, however, combines the advantages of traditional steam cracking (deep reaction depth, high ethylene and propylene yields) with catalytic cracking (low catalyst reaction temperature and wide feedstock range), effectively overcoming the aforementioned shortcomings.

[0003] The basic principle of catalytic cracking is to use a catalyst to promote the breakdown of hydrocarbons at relatively low temperatures. In this process, larger molecules are converted into smaller molecules, while free radicals are generated, further promoting the chain reaction. Compared to thermal cracking (cracking without a catalyst), catalytic cracking can be carried out at lower temperatures and under milder conditions, making it more economical and efficient. The key to catalytic cracking lies in the selection and design of the catalyst. Traditional catalysts are mainly acidic, such as zeolite molecular sieves, which are widely used due to their unique pore structure and acidic properties. These catalysts not only improve the selectivity of the reaction but also control the composition of the final product to a certain extent. For example, ZSM-5 molecular sieves have shown excellent performance in the preparation of high-quality fuels due to their unique pore structure and strong acidity.

[0004] However, despite their important role in the oil refining industry, these catalysts still have some limitations. First, traditional zeolite molecular sieve catalysts are primarily strongly acidic, resulting in low selectivity for specific compounds during catalytic cracking. While these acidic catalysts effectively promote hydrocarbon cracking, their effectiveness in increasing the yield of specific products, such as light olefins like propylene or ethylene, is limited. Second, catalyst deactivation is also a major challenge. During catalytic cracking, catalysts gradually lose activity due to high temperatures and carbon deposition. Although catalyst activity can be restored through regeneration processes, this increases operational complexity and cost. Furthermore, frequent regeneration cycles can affect the long-term stability and efficiency of the catalyst. Third, traditional catalysts perform poorly when handling feedstocks with high metal content. For example, in the catalytic cracking of naphtha light hydrocarbons, metallic contaminants such as nickel and vanadium can cause rapid catalyst deactivation, affecting reaction selectivity and product distribution.

[0005] To address the aforementioned issues, Chinese patent document CN101176849A discloses a catalyst and preparation method for highly selective propylene production. This method modifies the active component ZSM-5 molecular sieve catalyst by using rare earth elements to stabilize the molecular sieve structure, alkaline substances to alter surface acidity, and online silanization to modify the pores. The catalyst, used in fluidized bed reactions, is then prepared by spray drying. Chinese patent document CN106140262A discloses a supported catalyst and its preparation method. This supported catalyst consists of zinc oxide, zinc bromide, auxiliary oxides, and a magnesium-modified hydrogen-type ZSM-5 molecular sieve support. The preparation method includes the following steps: (1) treating the hydrogen-type ZSM-5 molecular sieve with a magnesium salt solution to obtain a magnesium-modified ZSM-5 molecular sieve support; (2) introducing zinc oxide into the magnesium-modified hydrogen-type ZSM-5 molecular sieve support; (3) brominated the support after introducing zinc oxide; (4) preparing the auxiliary oxides; and (5) introducing the auxiliary oxides into the brominated material from step (3). This catalyst can selectively convert bromomethane into isobutylene. Chinese patent document CN112691695A discloses a ZSM-5 molecular sieve catalyst, which includes at least ZSM-5 molecular sieve, SiO2, P element, and alkaline earth metal element and / or rare earth metal element; wherein, the ZSM-5 molecular sieve has an outer surface with acidic sites covered.

[0006] However, the aforementioned catalysts generally suffer from poor stability, low propylene yield, and low catalytic efficiency when used in the catalytic cracking of naphtha light hydrocarbons. In summary, the development of novel catalysts to improve the selectivity of naphtha light hydrocarbon catalytic cracking to obtain specific products, enhance catalyst stability, and increase catalytic efficiency would be of great significance to the field of catalytic cracking technology. Summary of the Invention

[0007] In view of this, the present invention provides a naphtha light hydrocarbon catalytic cracking catalyst and its preparation method. By combining magnesium hydroxide colloid with ZSM-5 molecular sieve, the magnesium hydroxide colloid provides an effective alkaline catalytic environment on the outer surface of the ZSM-5 molecular sieve, while retaining the acid catalytic performance inside the ZSM-5 molecular sieve. This structural innovation enables the catalyst to achieve highly efficient acid and alkaline catalysis in a single system. Combined with the introduction of Y-type molecular sieve, inorganic oxide binder, and clay components, a catalyst with excellent comprehensive performance is formed. This catalyst possesses both acid and alkaline catalytic functions, not only achieving highly efficient acid and alkaline catalysis in the naphtha light hydrocarbon catalytic cracking process and improving overall catalytic efficiency, particularly contributing to increased propylene and other light olefin production, but also expanding its application range, improving selectivity for specific products, and significantly enhancing catalyst stability, thus showing broad industrial application prospects.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A naphtha light hydrocarbon catalytic cracking catalyst, based on 100% of the total weight of the naphtha light hydrocarbon catalytic cracking catalyst, comprises 30% to 50% modified ZSM-5 molecular sieve on a dry basis, 3% to 10% Y-type molecular sieve on a dry basis, 25% to 40% inorganic oxide binder on an oxide basis, and 20% to 40% clay on a dry basis.

[0010] The preparation method of the modified ZSM-5 molecular sieve includes the following steps:

[0011] Under stirring, a pore-blocking agent with a particle size of less than 2 nm is added to a mixture of ZSM-5 molecular sieve and deionized water. Then, magnesium hydroxide colloid is added. After drying (preferably at 80-120°C) and calcining at 400-600°C for 2-10 hours, the pore-blocking agent is decomposed to obtain modified ZSM-5 molecular sieve.

[0012] In one alternative embodiment, the content of magnesium oxide is 1% to 10% based on the mass of the modified ZSM-5 molecular sieve and in terms of oxides.

[0013] In one alternative embodiment, the pore-blocking agent is selected from nano-silica sol or polymer nanoparticles; preferably, the polymer nanoparticles are selected from polyacrylic acid, polyethylene glycol, or polyvinyl alcohol.

[0014] In one optional embodiment, the amount of the added nano-silica sol is 5% to 15% of the mass of the ZSM-5 molecular sieve, based on silica.

[0015] In one optional embodiment, the amount of polymer nanoparticles added is 3% to 8% of the mass of the ZSM-5 molecular sieve.

[0016] In one optional embodiment, the preparation method of the modified ZSM-5 molecular sieve includes the following steps:

[0017] ZSM-5 molecular sieve was mixed with deionized water to obtain a mixed slurry;

[0018] Under stirring, a pore-blocking agent with a particle size of less than 2 nm is added to the mixed slurry. Thorough stirring ensures that the blocker is uniformly distributed and effectively penetrates the molecular sieve pores. Then, magnesium hydroxide colloid is slowly added to ensure uniform distribution and effective loading of the magnesium hydroxide colloid on the outer surface of the ZSM-5 molecular sieve. The mixture is then dried at 60–100°C to remove excess moisture. Subsequently, the dried mixture is calcined at 400–600°C over 2–10 hours using a gradual heating method to fix the magnesium hydroxide on the surface of the ZSM-5 molecular sieve, ensuring its stability and catalytic activity.

[0019] In one optional embodiment, the ZSM-5 molecular sieve is a ZSM-5 type molecular sieve containing modified elements; preferably, the silicon-aluminum ratio of the ZSM-5 molecular sieve used to prepare the ZSM-5 type molecular sieve containing modified elements is 25 to 100.

[0020] In one optional embodiment, the ZSM-5 molecular sieve containing modified elements is a phosphorus-metal composite modified ZSM-5 molecular sieve, wherein the phosphorus content is 1% to 10% based on the mass of the phosphorus-metal composite modified ZSM-5 molecular sieve as 100%, and the metal content is 0.5% to 5% based on the metal element.

[0021] In one optional embodiment, the preparation method of the phosphorus-metal composite modified ZSM-5 molecular sieve includes the following steps:

[0022] A phosphorus-containing compound or its aqueous solution is added to a mixture of ZSM-5 molecular sieve and deionized water to carry out the reaction, followed by the addition of a soluble metal salt to carry out the reaction. After drying (preferably at 80-130°C) and calcination, the phosphorus-metal composite modified ZSM-5 molecular sieve is obtained.

[0023] Preferably, the soluble metal salt is selected from at least one of the soluble salts of Zn, Fe, Ni and Co; the calcination is carried out in a dry atmosphere under normal pressure.

[0024] In one optional embodiment, during the preparation of the phosphorus-metal composite modified ZSM-5 molecular sieve, the reaction temperature of the phosphorus-containing compound or its aqueous solution is 20-100°C, and the reaction time is 0.5-2 hours; the reaction time of the soluble metal salt is 0.5-2 hours.

[0025] In one optional embodiment, during the preparation of the phosphorus-metal composite modified ZSM-5 molecular sieve, the calcination temperature is 300–800°C and the time is 0.5–4 h.

[0026] In one optional embodiment, the phosphorus-containing compound is selected from organophosphorus compounds and / or inorganic phosphorus compounds; the organophosphorus compounds are selected from at least one of trimethyl phosphate, triphenylphosphine, trimethyl phosphite, tetrabutylphosphine bromide, tetrabutylphosphine chloride, tetrabutylphosphine hydroxide, triphenylethylphosphine bromide, triphenylbutylphosphine bromide, triphenylbenzylphosphine bromide, hexamethylphosphoric acid triamine, dibenzyldiethylphosphine, and 1,3-xylenebistriethylphosphine; and the inorganic phosphorus compounds are selected from at least one of phosphoric acid, ammonium hydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, and boron phosphate.

[0027] In one optional embodiment, the method for preparing the magnesium hydroxide colloid includes the following steps:

[0028] Under stirring conditions, a surfactant was added to the magnesium salt solution, followed by the addition of an alkaline substance and the pH of the system was controlled at 9–11 to carry out the reaction, resulting in a stable magnesium hydroxide colloid.

[0029] Preferably, the magnesium salt solution contains 3% to 10% magnesium oxide by mass.

[0030] The amount of surfactant added is 0.5% to 5% of the mass of magnesium oxide in the magnesium salt solution.

[0031] In one optional embodiment, during the preparation of magnesium hydroxide colloid, the stirring rate is 300–600 rpm; the reaction temperature is 20–60°C; and the reaction time is 1–4 h.

[0032] In one optional embodiment, during the preparation of magnesium hydroxide colloid, the magnesium salt is a soluble magnesium salt, preferably at least one of magnesium chloride, magnesium sulfate, and magnesium nitrate.

[0033] The surfactant is selected from at least one of sodium dodecyl sulfate, polyvinylpyrrolidone, sodium dodecylbenzene sulfonate, etc.

[0034] The alkaline substance is selected from ammonia water; preferably, the pH of the ammonia water is ≤12.

[0035] In one optional embodiment, the method for preparing the magnesium hydroxide colloid includes the following steps:

[0036] A predetermined amount of magnesium salt is dissolved in a suitable solvent (such as deionized water) at a stirring rate of 300–600 rpm (20–60°C) to form a magnesium salt solution. A surfactant is then added and stirred until homogeneous. An alkaline substance is slowly added to the system containing the magnesium salt and surfactant using a titrator. During the addition of the alkaline substance, the pH value of the system is monitored and controlled in real time using a pH meter, maintaining it between 9 and 11. Simultaneously, continuous and constant stirring and temperature are maintained throughout the entire process of adding the alkaline substance to promote uniform nucleation and growth of magnesium hydroxide particles, while preventing excessive particle growth or aggregation. After a reaction of 1–4 hours, a stable magnesium hydroxide colloid is formed.

[0037] In one optional embodiment, the Y-type molecular sieve is selected from at least one of USY, REUSY, and REY; and the Na2O content is ≤1.0% based on 100% of the mass of the Y-type molecular sieve.

[0038] In one alternative embodiment, the clay is selected from at least one of kaolin, halloysite, montmorillonite, sepiolite, hydrotalcite, and rettoite.

[0039] In one alternative embodiment, the inorganic oxide binder comprises boehmite; preferably, the inorganic oxide binder further comprises at least one of aluminum sol, silica sol, and aluminosilicate sol.

[0040] The present invention also provides a method for preparing the above-mentioned naphtha light hydrocarbon catalytic cracking catalyst, comprising the following steps:

[0041] After mixing clay and inorganic oxide binder with deionized water, an acidic substance is added for gelation treatment, and then a soluble magnesium salt is added to form a colloid.

[0042] Modified ZSM-5 molecular sieve and Y-type molecular sieve were added to the colloid, mixed well, spray-dried, and then cured and calcined to obtain the naphtha light hydrocarbon catalytic cracking catalyst.

[0043] In one alternative embodiment, the inorganic oxide binder contains boehmite (calculated as alumina), and the mass ratio of the acidic substance to the boehmite in the inorganic oxide binder is 0.10 to 0.40.

[0044] In one optional embodiment, the temperature of the sol-gel treatment is 40–80°C; and the pH value of the colloid is ≥7.0.

[0045] In one alternative embodiment, the acidic substance is at least one of hydrochloric acid, nitric acid, formic acid, and acetic acid.

[0046] In one optional embodiment, the curing and calcination temperature is 300–600°C, and the time is 0.5–2 hours.

[0047] The beneficial effects of this invention are as follows:

[0048] The naphtha light hydrocarbon catalytic cracking catalyst provided by this invention pre-occupies the internal pores of a ZSM-5 molecular sieve with a pore-blocking agent, then combines magnesium hydroxide colloid with the ZSM-5 molecular sieve, and finally calcines to remove the pore-blocking agent and release the acidity inside the ZSM-5 molecular sieve, thereby optimizing the acid-base environment of the catalyst. Combined with components such as Y-type molecular sieves, inorganic oxide binders, and clay, it achieves highly efficient acidic and basic catalytic reactions, effectively improving the yield of propylene and other light olefins. Simultaneously, it enhances the catalyst's stability and resistance to deactivation, reduces catalyst loss costs, and facilitates stable plant operation. Overall, the naphtha light hydrocarbon catalytic cracking catalyst provided by this invention exhibits significant advantages in improving light olefin yield, enhancing catalyst stability, and improving anti-fouling capabilities, and has broad industrial application prospects. Attached Figure Description

[0049] Figure 1 The N2 adsorption-desorption curves of the modified ZSM-5 molecular sieves prepared in Example 3 and Comparative Example 2 of this invention are shown.

[0050] Figure 2 The N2 adsorption-desorption curves are shown for the modified ZSM-5 molecular sieves prepared in Example 6 and Comparative Example 3 of this invention. Detailed Implementation

[0051] 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.

[0052] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0053] 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.

[0054] Analysis and testing methods:

[0055] The pore structure of the samples was determined using a Micromeritics ASAP3000 automated physical adsorption analyzer.

[0056] raw material:

[0057] ZSM-5 molecular sieves were purchased from Tianjin Nanhua Catalyst Co., Ltd., with silicon-to-aluminum ratios of 30, 50, and 100.

[0058] Polyethylene glycol (molecular weight 1000), polyacrylic acid, Sinopharm reagent.

[0059] Y-type molecular sieves such as USY, REUSY, and REY are from the Catalyst Division of Lanzhou Petrochemical, with Na2O contents of 0.84%, 0.75%, and 0.42%, respectively.

[0060] The nano-silica sol was purchased from Guangdong Huierte Nanotechnology Co., Ltd. The average particle size of the nano-silica sol is less than 2 nanometers, and the silica content is 30%.

[0061] The alkaline silica sol binder was purchased from Qingdao Ocean Chemical Co., Ltd., and its silica content was 30%.

[0062] Kaolin and halloysite are both industrial products, supplied by the Catalyst Division of Lanzhou Petrochemical.

[0063] The raw materials listed above are not intended to limit the present invention. The present invention will be further illustrated by the following examples, but it is not believed that the present invention is limited to these examples.

[0064] Example 1

[0065] This embodiment provides a naphtha light hydrocarbon catalytic cracking catalyst, the preparation method of which includes the following steps:

[0066] (1) Preparation of phosphorus-metal composite modified ZSM-5 molecular sieve: Take 1037g of ZSM-5 molecular sieve with a silicon-to-aluminum ratio of 30, add 1117g of deionized water, stir evenly, add 16g of concentrated phosphoric acid, stir continuously at 95℃ for 0.5 hours, then add 36g of ferric nitrate nonahydrate, stir for 2 hours, then dry at 80℃ to remove moisture, and calcine at 300℃ for 4 hours to obtain phosphorus-iron composite modified ZSM-5 molecular sieve.

[0067] The phosphorus content (calculated as phosphorus pentoxide) in this phosphorus-metal composite modified ZSM-5 molecular sieve is 1%, and the iron content is 0.5%.

[0068] (2) Preparation of modified ZSM-5 molecular sieve: Weigh 151 g of magnesium chloride hexahydrate, add 449 g of deionized water, maintain a constant stirring speed of 300 rpm, control the reaction temperature at 20℃, so that the magnesium chloride is fully dissolved, then add 0.15 g of sodium dodecyl sulfate, slowly add ammonia water to maintain the pH value of the solution at 9.0-9.5, and continue stirring for 3 hours to obtain magnesium hydroxide colloidal solution for later use.

[0069] Take 968g of the prepared phosphorus-iron composite modified ZSM-5 molecular sieve, add 714g of deionized water, and add 167g of nano-silica sol while stirring continuously for 1 hour. Then add the prepared magnesium hydroxide colloidal solution, stir for 2 hours, filter, dry at 80℃ to remove moisture, use a programmed temperature rise (from room temperature to 400℃ in 2 hours), and solidify and calcine at 400℃ for 4 hours to obtain the modified ZSM-5 molecular sieve.

[0070] The modified ZSM-5 molecular sieve has a magnesium oxide content of 3%.

[0071] (3) Catalyst preparation: Take 476 g of boehmite, 886 g of kaolin, 857 g of alumina sol, and add 727 g of deionized water. Add 33 g of concentrated hydrochloric acid (concentration 36%–38%) while stirring continuously. Heat to 80°C and maintain for 40 minutes. Then add 101 g of magnesium chloride and stir until a colloid is formed. Add 619 g of the above-mentioned modified ZSM-5 molecular sieve and 244 g of REUSY molecular sieve, mix and stir until homogeneous, spray dry, and cure and calcine at 300°C for 2 hours to obtain the naphtha light hydrocarbon catalytic cracking catalyst. The sample is designated as S1.

[0072] Example 2

[0073] This embodiment provides a naphtha light hydrocarbon catalytic cracking catalyst, the preparation method of which includes the following steps:

[0074] (1) Preparation of phosphorus-metal composite modified ZSM-5 molecular sieve: Take 1021 g of ZSM-5 molecular sieve with a silicon-aluminum ratio of 30, add 1065 g of deionized water, stir evenly, add 32 g of concentrated phosphoric acid, stir continuously at 70°C for 1 hour, then add 72 g of ferric nitrate nonahydrate, stir for 0.5 hours, then dry at 90°C, and calcine at 400°C for 2 hours to obtain phosphorus-iron composite modified ZSM-5 molecular sieve.

[0075] The phosphorus-metal composite modified ZSM-5 molecular sieve contains 2% phosphorus (phosphorus pentoxide) by mass and 1% iron.

[0076] (2) Preparation of modified ZSM-5 molecular sieve: Weigh 227 g of magnesium chloride hexahydrate, add 898 g of deionized water, maintain a constant stirring speed of 400 rpm, control the reaction temperature at 30℃, so that the magnesium chloride is fully dissolved, then add 0.45 g of sodium dodecyl sulfate, slowly add ammonia water to maintain the pH value of the solution at 9.0-9.5, and continue stirring for 3 hours to obtain magnesium hydroxide colloidal solution for later use.

[0077] Take 932 g of the prepared phosphorus-iron composite modified ZSM-5 molecular sieve, add 256 g of deionized water, and add 50 g of polyethylene glycol while stirring continuously for 1 hour. Then add the prepared magnesium hydroxide colloidal solution, stir for 2 hours, filter, dry at 90℃, use a programmed temperature rise method (rise from room temperature to 400℃ in 4 hours), and cure and calcine at 400℃ for 2 hours to obtain the modified ZSM-5 molecular sieve.

[0078] The modified ZSM-5 molecular sieve has a magnesium oxide content of 4.5% by mass.

[0079] (3) Catalyst preparation: Take 476 g of boehmite, 772 g of kaolin, 952 g of alumina sol, and add 2446 g of deionized water. Add 60 g of concentrated hydrochloric acid (36%–38%) while stirring continuously. Heat to 70°C and maintain for 40 minutes. Then add 151 g of magnesium chloride and stir until homogeneous to form a colloid. Add 722 g of the above-mentioned modified ZSM-5 molecular sieve and 195 g of REUSY molecular sieve, mix and stir until homogeneous, spray dry, and cure and calcine at 400°C for 1 hour to obtain the naphtha light hydrocarbon catalytic cracking catalyst. The sample is designated as S2.

[0080] Example 3

[0081] This embodiment provides a naphtha light hydrocarbon catalytic cracking catalyst, the preparation method of which includes the following steps:

[0082] (1) Preparation of phosphorus-metal composite modified ZSM-5 molecular sieve: Take 979 g of ZSM-5 molecular sieve with a silicon-aluminum ratio of 50, add 1017 g of deionized water, stir evenly, add 65 g of concentrated phosphoric acid, stir continuously at 50°C for 2 hours, add 99 g of nickel nitrate, stir for 1 hour, then dry at 100°C, and calcine at 500°C for 2 hours to obtain phosphorus-nickel composite modified ZSM-5 molecular sieve.

[0083] The phosphorus-metal composite modified ZSM-5 molecular sieve contains 4% phosphorus (phosphorus pentoxide) by mass and 2% nickel.

[0084] (2) Preparation of modified ZSM-5 molecular sieve: Weigh 302 g of magnesium chloride hexahydrate, add 698 g of deionized water, maintain a constant stirring speed of 500 rpm, control the reaction temperature at 50℃, and allow the magnesium chloride to dissolve completely. Then add 1.2 g of sodium dodecylbenzenesulfonate, and slowly add ammonia water to maintain the pH value of the solution at 10.0-10.5. Continue stirring for 2 hours to obtain a magnesium hydroxide colloidal solution for later use.

[0085] Take 895g of the prepared phosphorus-nickel composite modified ZSM-5 molecular sieve, add 312g of deionized water, and add 90g of polyacrylic acid while stirring continuously for 2 hours. Then add the prepared magnesium hydroxide colloidal solution, stir for 2 hours, filter, dry at 100℃, use a programmed temperature rise method (from room temperature to 500℃ in 6 hours), and cure and calcine at 500℃ for 2 hours to obtain the modified ZSM-5 molecular sieve.

[0086] The modified ZSM-5 molecular sieve has a magnesium oxide content of 6%.

[0087] (3) Catalyst preparation: Take 508 g of boehmite, 663 g of kaolin, 952 g of aluminum sol, and add 2438 g of deionized water. Add 90 g of concentrated hydrochloric acid (36%–38%) while stirring continuously. Heat to 60°C and maintain for 60 minutes. Add 36 g of magnesium oxide and stir until homogeneous to form a colloid. Add 825 g of the above-mentioned modified ZSM-5 molecular sieve and 146 g of REY molecular sieve, mix and stir until homogeneous, spray dry, and cure and calcine at 450°C for 1 hour to obtain the naphtha light hydrocarbon catalytic cracking catalyst. The sample is designated as S3.

[0088] Example 4

[0089] This embodiment provides a naphtha light hydrocarbon catalytic cracking catalyst, the preparation method of which includes the following steps:

[0090] (1) Preparation of phosphorus-metal composite modified ZSM-5 molecular sieve: Take 927g of ZSM-5 molecular sieve with a silicon-to-aluminum ratio of 100, add 809g of deionized water, stir evenly, add 158g of trimethyl phosphate, stir continuously at 40℃ for 1 hour, add 148g of cobalt nitrate, stir for another hour, then dry at 120℃ and calcine at 600℃ for 0.5 hours to obtain phosphorus-cobalt composite modified ZSM-5 molecular sieve.

[0091] The phosphorus-metal composite modified ZSM-5 molecular sieve contains 8% phosphorus (phosphorus pentoxide) by mass and 3% cobalt.

[0092] (2) Preparation of modified ZSM-5 molecular sieve: Weigh 403 g of magnesium chloride hexahydrate, add 684 g of deionized water, maintain a constant stirring speed of 600 rpm, control the reaction temperature at 60℃ to fully dissolve the magnesium chloride, then add 2.4 g of sodium dodecyl sulfate, slowly add ammonia water to maintain the pH value of the solution at 10.5-11.0, and continue stirring for 2 hours to obtain a magnesium hydroxide colloidal solution for later use.

[0093] Take 863g of the prepared phosphorus-cobalt composite modified ZSM-5 molecular sieve, add 401g of deionized water, and add 333g of nano-silica sol while stirring continuously for 2 hours. Then add the prepared magnesium hydroxide colloidal solution, stir for 2 hours, filter, dry at 120℃, use a programmed temperature rise method (from room temperature to 550℃ in 8 hours), and cure and calcine at 550℃ for 2 hours to obtain the modified ZSM-5 molecular sieve.

[0094] The modified ZSM-5 molecular sieve has a magnesium oxide content of 8%.

[0095] (3) Catalyst preparation: Take 952 g of boehmite, 557 g of halloysite, and add 4482 g of deionized water. Add 92 g of concentrated hydrochloric acid (36%–38%) while continuously stirring. Heat to 60°C and maintain for 90 minutes. Then add 40 g of magnesium oxide and stir until homogeneous to form a colloid. Add 928 g of the above-mentioned modified ZSM-5 molecular sieve and 73 g of USY molecular sieve, mix and stir until homogeneous, spray dry, and cure and calcine at 600°C for 0.5 hours to obtain the naphtha light hydrocarbon catalytic cracking catalyst. The sample is designated as S4.

[0096] Example 5

[0097] This embodiment provides a naphtha light hydrocarbon catalytic cracking catalyst, the preparation method of which includes the following steps:

[0098] (1) Preparation of phosphorus-metal composite modified ZSM-5 molecular sieve: Take 896g of ZSM-5 molecular sieve with a silicon-aluminum ratio of 25, add 932g of deionized water, stir evenly, add 167g of diammonium hydrogen phosphate, stir continuously at 20℃ for 1 hour, add 227g of zinc nitrate, stir for 2 hours, then dry at 90℃, and calcine at 700℃ for 1 hour to obtain phosphorus-zinc composite modified ZSM-5 molecular sieve.

[0099] The phosphorus-metal composite modified ZSM-5 molecular sieve contains 9% phosphorus (phosphorus pentoxide) by mass and 5% zinc.

[0100] (2) Preparation of modified ZSM-5 molecular sieve: Weigh 508 g of magnesium nitrate hexahydrate, add 635 g of deionized water, maintain a constant stirring speed of 600 rpm, control the reaction temperature at 40℃, so that magnesium chloride is fully dissolved, then add 4 g of sodium dodecylbenzenesulfonate, slowly add ammonia water to maintain the pH value of the solution at 10.5-11.0, and continue stirring for 2 hours to obtain magnesium hydroxide colloidal solution for later use.

[0101] Take 937 g of the prepared phosphorus-zinc composite modified ZSM-5 molecular sieve, add 360 g of deionized water, and add 30 g of polyacrylic acid while continuously stirring for 2 hours. Then add the prepared magnesium hydroxide colloidal solution, stir for 2 hours, filter, dry at 120℃, and use a programmed temperature rise method (from room temperature to 550℃ in 7 hours), and cure and calcine at 550℃ for 2 hours to obtain the modified ZSM-5 molecular sieve. The magnesium oxide content of this modified ZSM-5 molecular sieve is 8%.

[0102] (3) Catalyst preparation: Take 571 g of boehmite, 557 g of kaolin, 952 g of alumina sol, and add 2431 g of deionized water. Add 108 g of concentrated hydrochloric acid (36%–38%) while stirring continuously. Heat to 60°C and maintain for 90 minutes. Add 40 g of magnesium oxide and stir until homogeneous to form a colloid. Add 928 g of the above-mentioned modified ZSM-5 molecular sieve and 73 g of USY molecular sieve, mix and stir until homogeneous, spray dry, and cure and calcine at 450°C for 1 hour to obtain the naphtha light hydrocarbon catalytic cracking catalyst. The sample is designated as S5.

[0103] Example 6

[0104] This embodiment provides a naphtha light hydrocarbon catalytic cracking catalyst, the preparation method of which includes the following steps:

[0105] (1) Preparation of phosphorus-metal composite modified ZSM-5 molecular sieve: Take 958g of ZSM-5 molecular sieve with a silicon-aluminum ratio of 30, add 895g of deionized water, stir evenly, add 75g of boron phosphate, stir continuously at 70℃ for 1 hour, add 136g of zinc nitrate, stir for another hour, then dry at 130℃, and calcine at 550℃ for 1 hour to obtain phosphorus-zinc composite modified ZSM-5 molecular sieve.

[0106] The phosphorus-metal composite modified ZSM-5 molecular sieve contains 5% phosphorus (phosphorus pentoxide) by mass and 3% zinc.

[0107] (2) Preparation of modified ZSM-5 molecular sieve: Weigh 603 g of magnesium nitrate hexahydrate, add 2500 g of deionized water, maintain a constant stirring speed of 600 rpm, control the reaction temperature at 30℃, so that magnesium chloride is fully dissolved, then add 3.5 g of sodium dodecyl sulfate, slowly add ammonia water to maintain the pH value of the solution at 10.0-10.5, and continue stirring for 3 hours to obtain magnesium hydroxide colloidal solution for later use.

[0108] Take 805 g of the prepared phosphorus-zinc composite modified ZSM-5 molecular sieve, add 250 g of deionized water, and add 383 g of nano-silica sol while continuously stirring for 2 hours. Then add the prepared magnesium hydroxide colloidal solution, stir for 2 hours, filter, dry at 100℃, and use a programmed temperature rise method (from room temperature to 600℃ in 10 hours), and cure and calcine at 600℃ for 1 hour to obtain the modified ZSM-5 molecular sieve. The magnesium oxide content of this modified ZSM-5 molecular sieve is 9.5%.

[0109] (3) Catalyst preparation: Take 571 g of boehmite, 430 g of halloysite, 952 g of aluminum sol, and add 2455 g of deionized water. Add 140 g of formic acid while stirring continuously. Heat to 50 °C and maintain for 60 minutes. Then add 254 g of magnesium nitrate and stir evenly to form a colloid. Add 1031 g of the above modified ZSM-5 molecular sieve and 75 g of REUSY molecular sieve, mix and stir evenly, spray dry, and cure and calcine at 450 °C for 0.5 hours to obtain the naphtha light hydrocarbon catalytic cracking catalyst. The sample is designated as S6.

[0110] Example 7

[0111] This embodiment provides a naphtha light hydrocarbon catalytic cracking catalyst, the preparation method of which includes the following steps:

[0112] (1) Preparation of phosphorus-metal composite modified ZSM-5 molecular sieve: Take 979g of ZSM-5 molecular sieve with a silicon-aluminum ratio of 30, add 1053g of deionized water, stir evenly, add 67g of boron phosphate, stir continuously at 70℃ for 1 hour, add 68g of zinc nitrate, stir for another hour, then dry at 80℃, and calcine at 600℃ for 1 hour to obtain phosphorus-zinc composite modified ZSM-5 molecular sieve.

[0113] The phosphorus content (calculated as phosphorus pentoxide) and zinc content (calculated as phosphorus pentoxide) in this phosphorus-metal composite modified ZSM-5 molecular sieve are 4.5% and 1.5% respectively.

[0114] (2) Preparation of modified ZSM-5 molecular sieve: Weigh 95 g of magnesium nitrate hexahydrate, add 190 g of deionized water, maintain a constant stirring speed of 500 rpm, control the reaction temperature at 30℃, so that magnesium chloride is fully dissolved, then add 0.4 g of sodium dodecyl sulfate, slowly add ammonia water to maintain the pH value of the solution at 9.5-10.0, and continue stirring for 2 hours to obtain magnesium hydroxide colloidal solution for later use.

[0115] Take 953 g of the prepared phosphorus-zinc composite modified ZSM-5 molecular sieve, add 705 g of deionized water, and add 70 g of polyethylene glycol while continuously stirring for 2 hours. Then add the prepared magnesium hydroxide colloidal solution, stir for 2 hours, filter, dry at 120℃, and use a programmed temperature rise method (from room temperature to 400℃ in 5 hours), and cure and calcine at 400℃ for 1 hour to obtain the modified ZSM-5 molecular sieve. The magnesium oxide content of this modified ZSM-5 molecular sieve is 1.5% by mass.

[0116] (3) Catalyst preparation: Take 540 g of boehmite, 537 g of kaolin, 1048 g of alumina sol, and add 2325 g of deionized water. Add 85 g of concentrated hydrochloric acid (36%–38%) while stirring continuously. Heat to 50°C and maintain for 60 minutes. Add 229 g of magnesium nitrate and stir until homogeneous to form a colloid. Add 866 g of the modified ZSM-5 molecular sieve and 171 g of REUSY molecular sieve, mix and stir until homogeneous, spray dry, and cure and calcine at 450°C for 0.5 hours to obtain the naphtha light hydrocarbon catalytic cracking catalyst. The sample is designated as S7.

[0117] Comparative Example 1

[0118] This comparative example is similar to Example 2, except that magnesium chloride solution is used instead of magnesium hydroxide colloid. The preparation method of the naphtha light hydrocarbon catalytic cracking catalyst provided in this comparative example includes the following steps:

[0119] (1) Preparation of phosphorus-metal composite modified ZSM-5 molecular sieve: same as in Example 2.

[0120] (2) Preparation of modified ZSM-5 molecular sieve: Weigh 227 g of magnesium chloride hexahydrate, add 898 g of deionized water, maintain a constant stirring speed of 400 rpm, control the reaction temperature at 30℃, so that the magnesium chloride is fully dissolved to obtain a magnesium chloride solution for later use.

[0121] Take 932 g of the prepared phosphorus-iron composite modified ZSM-5 molecular sieve, add 256 g of deionized water, and add 50 g of polyethylene glycol while stirring continuously for 1 hour. Then add the prepared magnesium chloride solution, stir for 2 hours, filter, dry at 90℃, use a programmed temperature rise method (rise from room temperature to 400℃ in 4 hours), and cure and calcine at 400℃ for 2 hours to obtain the modified ZSM-5 molecular sieve.

[0122] (3) Catalyst preparation: Take 476 g of boehmite, 772 g of kaolin, 952 g of alumina sol, and add 2446 g of deionized water. Add 60 g of hydrochloric acid with a concentration of 36%–38% while stirring continuously. Heat to 70°C and maintain for 40 minutes. Then add 151 g of magnesium chloride and stir until a colloid is formed. Add 722 g of the above-mentioned modified ZSM-5 molecular sieve and 195 g of REUSY molecular sieve, mix and stir until homogeneous, spray dry, and cure and calcine at 400°C for 1 hour to obtain the naphtha light hydrocarbon catalytic cracking catalyst. The sample is designated as D1.

[0123] Comparative Example 2

[0124] This comparative example is similar to Example 3, except that: this comparative example did not use programmed temperature rise when preparing the modified ZSM-5 molecular sieve. The preparation method of the naphtha light hydrocarbon catalytic cracking catalyst provided in this comparative example includes the following steps:

[0125] (1) Preparation of phosphorus-metal composite modified ZSM-5 molecular sieve: Same as in Example 3.

[0126] (2) Preparation of modified ZSM-5 molecular sieve: Weigh 302 g of magnesium chloride hexahydrate, add 698 g of deionized water, maintain a constant stirring speed of 500 rpm, control the reaction temperature at 50℃, so that the magnesium chloride is fully dissolved, then add 1.2 g of sodium dodecyl sulfate, slowly add ammonia water to maintain the pH value of the solution at 10.0-10.5, and continue stirring for 2 hours to obtain magnesium hydroxide colloidal solution for later use.

[0127] Take 895 g of the prepared phosphorus-nickel composite modified ZSM-5 molecular sieve, add 312 g of deionized water, and stir continuously until homogeneous. Add 90 g of polyacrylic acid while stirring continuously for 2 hours. Then add the prepared magnesium hydroxide colloidal solution, stir for 2 hours, filter, dry at 100℃, and then cure and calcine at 500℃ for 2 hours to obtain the modified ZSM-5 molecular sieve.

[0128] (3) Catalyst preparation: Take 508 g of boehmite, 663 g of kaolin, 952 g of alumina sol, and add 2438 g of deionized water. Add 90 g of hydrochloric acid with a concentration of 36%–38% while stirring continuously. Heat to 60°C and maintain for 60 minutes. Then add 36 g of magnesium oxide and stir evenly to form a colloid. Add 825 g of the above-mentioned modified ZSM-5 molecular sieve and 146 g of REY molecular sieve, mix and stir evenly, spray dry, and cure and calcine at 450°C for 1 hour to obtain the naphtha light hydrocarbon catalytic cracking catalyst. The sample is designated as D2.

[0129] Comparative Example 3

[0130] This comparative example is similar to Example 7, except that no pore-blocking agent was used. The preparation method of the naphtha light hydrocarbon catalytic cracking catalyst provided in this comparative example includes the following steps:

[0131] (1) Preparation of phosphorus-metal composite modified ZSM-5 molecular sieve: same as in Example 7.

[0132] (2) Preparation of modified ZSM-5 molecular sieve: Weigh 95 g of magnesium nitrate hexahydrate, add 190 g of deionized water, maintain a constant stirring speed of 500 rpm, control the reaction temperature at 30℃, so that magnesium chloride is fully dissolved, then add 0.4 g of sodium dodecyl sulfate, slowly add ammonia water to maintain the pH value of the solution at 9.5-10.0, and continue stirring for 2 hours to obtain magnesium hydroxide colloidal solution for later use.

[0133] Take 953g of the prepared phosphorus-zinc composite modified ZSM-5 molecular sieve, add 705g of deionized water, stir evenly, then add the prepared magnesium hydroxide colloidal solution, stir for 2 hours, filter, dry at 120℃, use a programmed temperature rise method (5 hours from room temperature to 400℃), and solidify and calcine at 400℃ for 1 hour to obtain the modified ZSM-5 molecular sieve.

[0134] (3) Catalyst preparation: Take 540 g of boehmite, 537 g of kaolin, 1048 g of alumina sol, and add 2325 g of deionized water. Add 85 g of concentrated hydrochloric acid (36%–38%) while stirring continuously. Heat to 50°C and maintain for 60 minutes. Add 229 g of magnesium nitrate and stir until homogeneous to form a colloid. Add 866 g of the modified ZSM-5 molecular sieve and 171 g of REUSY molecular sieve, mix and stir until homogeneous, spray dry, and cure and calcine at 450°C for 0.5 hours to obtain the naphtha light hydrocarbon catalytic cracking catalyst. The sample is designated as D3.

[0135] The modified ZSM-5 molecular sieves prepared in each embodiment and comparative example, as well as the unmodified phosphorus-metal composite modified ZSM-5 molecular sieve, were subjected to pore structure testing. The results showed that the modified ZSM-5 molecular sieves prepared in each embodiment had high specific surface area and pore volume, indicating that the plugging agent completely decomposed and released the internal pores of the molecular sieve, and that the silica generated after the thermal decomposition of the nano-silica sol did not block the internal pores of the molecular sieve. Simultaneously, magnesium oxide did not block the external pores of the molecular sieve. Conversely, the modified ZSM-5 molecular sieves prepared in each comparative example showed significantly reduced specific surface area and pore volume. The following examples, specifically Example 3 and Comparative Example 2, Example 6 and Comparative Example 3, will be used to illustrate this further. Figure 1 and Figure 2 The N2 adsorption-desorption curves for Example 3 and Comparative Example 2, and Example 6 and Comparative Example 3 are shown in the figure. Figure 1 and Figure 2 And the data in the table below.

[0136] Table 1 Specific surface area and pore volume

[0137] Sample Name <![CDATA[Specific surface area / (m 2 ·g -1 )]]> <![CDATA[Pore volume / (mL·g -1 )]]> Phosphorus-nickel composite modified ZSM-5 molecular sieve 324.8 0.124 Example 3 312.4 0.121 Comparative Example 2 212.5 0.058 Phosphorus-zinc composite modified ZSM-5 molecular sieve 327.9 0.128 Example 6 316.7 0.125 Comparative Example 3 201.3 0.047

[0138] Depend on Figure 1 and Figure 2 As shown in the table above, the modified ZSM-5 molecular sieve prepared using the method of this invention exhibits significantly better specific surface area and pore volume compared to the unmodified sieve. This indicates that during the modification process, magnesium species are uniformly distributed on the surface of the molecular sieve, rather than clogging the pores. Therefore, the pores of the molecular sieve are preserved, ensuring a larger specific surface area and pore volume. Conversely, the molecular sieve prepared in the comparative example suffers from pore blockage due to uneven distribution and accumulation of magnesium species within the pores, resulting in a significant reduction in specific surface area and pore volume. This result demonstrates that the magnesium modification method of this invention effectively avoids pore blockage, maintains the pore structure advantages of the molecular sieve, and thus benefits the catalytic reaction and improves catalyst performance.

[0139] Catalyst evaluation:

[0140] The catalytic cracking catalysts prepared in each example and comparative example were evaluated for their reaction performance in a microreactor, and tested according to the NB / SH / T 0952 test standard. Before testing, the catalytic cracking catalysts were treated at 800℃ with 100% water vapor for 4 hours and 17 hours to obtain the catalyst activity retention rate.

[0141] Table 2

[0142] project S1 S2 S3 S4 S5 S6 S7 D1 D2 D3 4-hour activity 68 69 67 66 66 67 68 50 49 48 17-hour activity 58 58 57 56 55 57 60 31 30 29 Activity retention rate 0.85 0.84 0.85 0.85 0.83 0.85 0.88 0.62 0.61 0.60

[0143] The catalytic cracking catalysts prepared in each embodiment and comparative example were evaluated for their reaction performance in a microreactor to obtain the effect of the catalysts on the yield of ethylene and propylene. The feedstock was naphtha, the reaction temperature was 570℃, and the catalyst-to-oil ratio was 7.

[0144] Table 3

[0145]

[0146] Based on the evaluation data of each embodiment (S1-S7) and comparative example (D1-D3) in the table above, the following conclusions are drawn:

[0147] Based on the activity data, after 4 hours of treatment at 800℃ with 100% steam, the activity values ​​of S1-S7 were all between 66 and 69, while the activity values ​​of the comparative examples D1-D3 were significantly lower, only between 48 and 50. After 17 hours of treatment, the activity of S1-S7 decreased slightly, but still remained between 55 and 60, with an activity retention rate of approximately 0.83-0.88, showing high stability. In contrast, the activity of D1-D3 decreased more significantly after 17 hours of treatment, remaining only at 29-31, with a retention rate of 0.60-0.62, exhibiting poor stability.

[0148] In terms of product distribution, the LPG yields of S1-S7 ranged from 50.10% to 53.66%, while the yields of ethylene and propylene were 5.84%-6.25% and 20.70%-22.69%, respectively. In contrast, the LPG yields of D1-D3 were significantly lower, ranging only from 34.34% to 39.29%, and the yields of ethylene and propylene also decreased substantially, with ethylene at only 1.15%-2.22% and propylene at 12.65%-15.85%.

[0149] In summary, S1-S7 exhibit higher activity, better activity retention, and superior ethylene and propylene yields compared to D1-D3. This indicates that the catalysts prepared by the method provided in this invention are significantly superior to the comparative examples in terms of hydrothermal stability and catalytic performance, especially in maintaining high activity and excellent product selectivity even after high-temperature steam treatment.

[0150] 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 naphtha light hydrocarbon catalytic cracking catalyst, characterized in that, The total weight of the naphtha light hydrocarbon catalytic cracking catalyst is 100%, including 30% to 50% modified ZSM-5 molecular sieve on a dry basis, 3% to 10% Y-type molecular sieve on a dry basis, 25% to 40% inorganic oxide binder on an oxide basis, and 20% to 40% clay on a dry basis. The preparation method of the modified ZSM-5 molecular sieve includes the following steps: Under stirring, a pore-blocking agent with a particle size of less than 2 nm is added to a mixture of ZSM-5 molecular sieve and deionized water. Then, magnesium hydroxide colloid is added. After drying, the mixture is calcined at 400-600℃ for 2-10 hours to decompose the pore-blocking agent, thereby obtaining modified ZSM-5 molecular sieve.

2. The naphtha light hydrocarbon catalytic cracking catalyst as described in claim 1, characterized in that, Based on the mass of the modified ZSM-5 molecular sieve as 100%, the content of magnesium oxide is 1% to 10% in terms of oxides.

3. The naphtha light hydrocarbon catalytic cracking catalyst as described in claim 1, characterized in that, The pore blocking agent is selected from nano-silica sol or polymer nanoparticles; preferably, the polymer nanoparticles are selected from polyacrylic acid, polyethylene glycol, or polyvinyl alcohol.

4. The naphtha light hydrocarbon catalytic cracking catalyst as described in claim 3, characterized in that, The amount of the nano-silica sol added is 5% to 15% of the mass of the ZSM-5 molecular sieve, based on silica.

5. The naphtha light hydrocarbon catalytic cracking catalyst as described in claim 3, characterized in that, The amount of polymer nanoparticles added is 3% to 8% of the mass of the ZSM-5 molecular sieve.

6. The naphtha light hydrocarbon catalytic cracking catalyst as described in claim 1, characterized in that, The ZSM-5 molecular sieve is a ZSM-5 type molecular sieve containing modified elements.

7. The naphtha light hydrocarbon catalytic cracking catalyst as described in claim 6, characterized in that, The modified ZSM-5 molecular sieve is derived from a phosphorus-metal composite modified ZSM-5 molecular sieve. Based on the mass of the phosphorus-metal composite modified ZSM-5 molecular sieve as 100%, the phosphorus content is 1%-10% based on phosphorus pentoxide, and the metal content is 0.5%-5% based on elemental metal.

8. The naphtha light hydrocarbon catalytic cracking catalyst as described in claim 7, characterized in that, The preparation method of the phosphorus-metal composite modified ZSM-5 molecular sieve includes the following steps: A phosphorus-containing compound or its aqueous solution is added to a mixture of ZSM-5 molecular sieve and deionized water to carry out the reaction, followed by the addition of a soluble metal salt. After drying and calcination, the phosphorus-metal composite modified ZSM-5 molecular sieve is obtained. Preferably, the soluble metal salt is selected from at least one of the soluble salts of Zn, Fe, Ni and Co; the calcination is carried out in a dry atmosphere under normal pressure.

9. The naphtha light hydrocarbon catalytic cracking catalyst as described in claim 8, characterized in that, The reaction temperature for adding the phosphorus-containing compound or its aqueous solution is 20–100°C, and the reaction time is 0.5–2 h. The reaction time for adding the soluble metal salt is 0.5–2 h. The roasting temperature is 300–700℃, and the time is 0.5–4 hours.

10. The naphtha light hydrocarbon catalytic cracking catalyst as described in claim 8, characterized in that, The phosphorus-containing compound is selected from organophosphorus compounds and / or inorganic phosphorus compounds; the organophosphorus compound is selected from at least one of trimethyl phosphate, triphenylphosphine, trimethyl phosphite, tetrabutylphosphine bromide, tetrabutylphosphine chloride, tetrabutylphosphine hydroxide, triphenylethylphosphine bromide, triphenylbutylphosphine bromide, triphenylbenzylphosphine bromide, hexamethylphosphoric acid triamine, dibenzyldiethylphosphine, and 1,3-xylenebistriethylphosphine; and the inorganic phosphorus compound is selected from at least one of phosphoric acid, ammonium hydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, and boron phosphate.

11. The naphtha light hydrocarbon catalytic cracking catalyst according to any one of claims 1-10, characterized in that, The preparation method of the magnesium hydroxide colloid includes the following steps: Under stirring conditions, a surfactant was added to the magnesium salt solution, followed by the addition of an alkaline substance and the pH of the system was controlled at 9–11 to carry out the reaction, resulting in a stable magnesium hydroxide colloid. Preferably, the magnesium salt solution contains 3% to 10% magnesium oxide by mass. The amount of surfactant added is 0.5% to 5% of the mass of magnesium oxide in the magnesium salt solution.

12. The naphtha light hydrocarbon catalytic cracking catalyst according to claim 1, characterized in that, The Y-type molecular sieve is selected from at least one of USY, REUSY, and REY; based on the mass of the Y-type molecular sieve as 100%, the content of Na2O is ≤1.0%; The clay is selected from at least one of kaolin, halloysite, montmorillonite, sepiolite, hydrotalcite and rettoite; The inorganic oxide binder includes boehmite; preferably, the inorganic oxide binder further includes at least one of aluminum sol, silica sol, and aluminosilicate sol.

13. A method for preparing the naphtha light hydrocarbon catalytic cracking catalyst according to any one of claims 1-12, characterized in that, Includes the following steps: After mixing clay, inorganic oxide binder and deionized water, an acidic substance is added for gelation treatment, and then a soluble magnesium salt is added to form a colloid. Modified ZSM-5 molecular sieve and Y-type molecular sieve were added to the colloid, mixed well, spray-dried, and then cured and calcined to obtain the naphtha light hydrocarbon catalytic cracking catalyst.

14. The preparation method according to claim 13, characterized in that, The inorganic oxide binder, based on alumina, contains boehmite, and the mass ratio of the acidic substance to the boehmite in the inorganic oxide binder is 0.10 to 0.

40. The temperature for the sol-gel treatment is 40–80°C; The acidic substance is at least one of hydrochloric acid, nitric acid, formic acid, and acetic acid.

15. The preparation method according to claim 13, characterized in that, The curing and calcination temperature is 300–600℃, and the time is 0.5–2 hours.

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