Core-shell structured cracking reaction catalyst and method for preparing the same

Abstract

The application provides a core-shell structure cracking reaction catalyst and a preparation method thereof. The preparation method comprises the following steps: sequentially performing aluminum dissolution treatment and silicon dissolution treatment on waste molecular sieves to obtain an aluminum-rich liquid and a silicon-rich liquid; sequentially performing gelation treatment, aging treatment and hydrothermal crystallization treatment on raw materials including the aluminum-rich liquid, the silicon-rich liquid and seeds to obtain 13X molecular sieves; sequentially performing first impregnation treatment and second impregnation treatment on the 13X molecular sieves in a silanization reagent solution and a nickel-containing solution to obtain nickel-modified 13X molecular sieves; sequentially performing first hydrothermal reaction and calcination treatment on the nickel-modified 13X molecular sieves and a titanium-silicon molecular sieve precursor solution to obtain core-shell structure 13X molecular sieves; and mixing and stirring the core-shell structure 13X molecular sieves and a platinum precursor solution, then sequentially performing solid-liquid separation, drying, pre-calcination treatment and first calcination treatment to obtain the core-shell structure cracking reaction catalyst, which has high catalytic activity in catalytic cracking reaction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cracking reaction catalyst preparation, in particular to a core-shell structure cracking reaction catalyst and a preparation method thereof. BACKGROUND

[0002] Molecular sieve is a kind of silicate, which has the characteristics of uniform pore size, regular crystal structure, rich pore system, large specific surface area and good thermal stability, etc. Therefore, molecular sieve is considered as the preferred adsorbent material for removing oxygen-containing compounds from olefins. Among them, the FAU type molecular sieve includes X type molecular sieve and Y type molecular sieve, and the pore size of the FAU type molecular sieve is about 0.74 nm. The X type molecular sieve in the FAU type molecular sieve can better remove oxygen-containing compound impurities in olefins, so it is studied more and has been applied in industrial practice.

[0003] The 13X molecular sieve in the X type molecular sieve has a uniform and ordered microporous structure, which can realize precise molecular selection. Specifically, the micropore size and shape of the 13X molecular sieve can highly specifically adsorb molecules of specific size and shape, while excluding other molecules, which is very valuable in the separation and purification process of the chemical industry. For example, in the field of gas separation, the 13X molecular sieve can effectively separate target gases such as oxygen, nitrogen or carbon dioxide from a mixed gas stream. The 13X molecular sieve has a large specific surface area, which can provide more active adsorption sites, thereby increasing the adsorption capacity of the 13X molecular sieve. This means that the 13X molecular sieve can adsorb more substances in the same physical volume, thereby improving the processing rate and efficiency. The adsorption capacity of the 13X molecular sieve is particularly important in the fields of liquid or gas purification, catalyst carriers and storage media.

[0004] Therefore, the 13X molecular sieve with uniform and ordered micropores, large specific surface area and large pore volume not only shows great potential in traditional chemical, petroleum and natural gas processing fields, but also demonstrates broad application prospects in emerging fields such as environmental protection, clean energy and life science. For example, in the treatment of industrial waste gas, the 13X molecular sieve can effectively remove harmful gases and volatile organic compounds (VOCs); in the production of pharmaceuticals and fine chemicals, the 13X molecular sieve can be used to improve the purity and yield of products.

[0005] However, the prior art synthesis of 13X molecular sieve has the problems of low utilization rate of silicon source, uncontrollable product size and morphology, and poor dispersity. Patent No. CN103523796B discloses a preparation method of sub-micron X-type molecular sieve and its application in the separation and adsorption of hydrocarbons. Specifically, a directing agent is prepared by using silica sol as a silicon source, a mother liquor of the molecular sieve is prepared by using water glass, sodium hydroxide and aluminum hydroxide, the mother liquor of the molecular sieve is added to the directing agent for aging, a weak polar dispersant is added after aging, microwave-assisted crystallization is adopted, and finally sub-micron X-type molecular sieve is obtained. The X-type molecular sieve prepared by the above method has small crystal grains, short synthesis time and low production cost. The adsorbent product prepared by using the sub-micron X-type molecular sieve has the characteristics of large adsorption capacity and easy regeneration, is suitable for deep removal of oxygen-containing impurities in hydrocarbon streams, and the 13X molecular sieve is made into a catalyst, which has the problem of low catalytic efficiency in catalytic cracking reaction. SUMMARY

[0006] The main purpose of the present application is to provide a core-shell structure cracking reaction catalyst and a preparation method thereof, so as to solve the problem of low cracking reaction efficiency in the prior art.

[0007] In order to achieve the above purpose, according to one aspect of the present application, a preparation method of a core-shell structure cracking reaction catalyst is provided, which comprises the following steps: step S1, sequentially performing aluminum dissolution treatment and silicon dissolution treatment on waste molecular sieve to obtain an aluminum-rich liquid and a silicon-rich liquid; step S2, sequentially performing gelation treatment, aging treatment and hydrothermal crystallization treatment on raw materials including the aluminum-rich liquid, the silicon-rich liquid and seed crystals to obtain 13X molecular sieve; step S3, sequentially performing first impregnation treatment and second impregnation treatment on the 13X molecular sieve in a silanization reagent solution and a nickel-containing solution to obtain nickel-modified 13X molecular sieve; step S4, sequentially performing first hydrothermal reaction and calcination treatment on the nickel-modified 13X molecular sieve and a titanium-silicon molecular sieve precursor solution to obtain core-shell structure 13X molecular sieve; and step S5, mixing the core-shell structure 13X molecular sieve with a platinum precursor solution, and then sequentially performing solid-liquid separation, drying, pre-calcination treatment and first calcination treatment to obtain the core-shell structure cracking reaction catalyst.

[0008] Further, in the step S3, the time of the first impregnation treatment is 8-24 h; and / or, the time of the second impregnation treatment is 24-48 h; preferably, the molar concentration of the silanization reagent solution is 0.05-0.2 mol / L; and / or, the molar concentration of the nickel-containing solution is 0.05-0.2 mol / L; preferably, the mass of the 13X molecular sieve to the volume of the silanization reagent solution is 400-600: 1 g / L; and / or, the mass of the 13X molecular sieve to the volume of the nickel-containing solution is 400-600: 1 g / L; preferably, the nickel-containing solution is a nickel nitrate solution and / or a nickel sulfate solution; preferably, the silanization reagent is selected from any one or more of 3-aminopropyltriethoxysilane, tetraethoxysilane and tetramethoxysilane; preferably, the step S3 further comprises: subjecting the 13X molecular sieve obtained from the second impregnation treatment to a third calcination to obtain a nickel-modified 13X molecular sieve coated with a layer of nickel nanoparticles; and / or, the atmosphere of the third calcination is hydrogen, the temperature of the third calcination is 500-600 °C, and the time of the third calcination is 2-4 h.

[0009] Further, in the step S4, the temperature of the first hydrothermal reaction is 150-200 °C, and the time of the first hydrothermal reaction is 12-24 h; and / or, the temperature of the calcination treatment is 450-550 °C, and the time of the calcination treatment is 4-8 h; the titanium-silicon molecular sieve precursor solution comprises a first silicon source, a titanium source, a template agent, a fluorine complex and water, wherein the first silicon source, the titanium source, the template agent, the fluorine complex and the water are mixed in a molar ratio of 1:0.04-0.1:0.1-0.3:0.03-0.06:20-50; and / or, the mass of the nickel-modified 13X molecular sieve to the volume of the titanium-silicon molecular sieve precursor solution is 400-600: 1 g / L; preferably, the first silicon source is selected from any one or more of Si02, Na2Si03 and Si(OC2H5)4; preferably, the titanium source is selected from any one or more of Ti02, TiCl4 and Na2Ti03; preferably, the fluorine complex is selected from any one or more of sodium hexafluorophosphate, sodium hexafluoroacetyl acetonate and ammonium fluoride; preferably, the template agent is an organic amine and / or a quaternary ammonium salt.

[0010] Further, in the step S5, the mixing is preferably performed with stirring, and the stirring time is preferably 12-36 h; the mass concentration of the platinum precursor solution is preferably 2-3 g / L; the platinum precursor solution is preferably hexachloroplatinic acid dihydrate; the mass ratio of the core-shell structure 13X molecular sieve to the volume of the platinum precursor solution is preferably 1:5 g / L; and / or, the atmosphere for the pre-calcination treatment is an inert gas, and / or, the temperature for the pre-calcination treatment is 450-550°C; and / or, the time for the pre-calcination treatment is 1-3 h; and / or, the temperature for the first calcination treatment is 700-900°C; and / or, the time for the first calcination treatment is 3-5 h; and / or, the atmosphere for the first calcination treatment is air; and / or, the temperature for the drying is 90-130°C, and the time for the drying is 8-16 h.

[0011] Further, in the step S2, the 13X molecular sieve contains silicon and aluminum elements, and the molar ratio of the silicon element to the aluminum element is 2.2-2.9:1; and / or, the pore volume of the 13X molecular sieve is 0.3-0.5 cm 3 / g; and / or, the specific surface area of the 13X molecular sieve is 700-950 m 2 / g.

[0012] Further, the seed crystal contains SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of SiO2 to Al2O3 is 0.01-2.5:1, and the molar ratio of Na2O, H2O to SiO2 is 0.01-4.0:1.0-40.0:1.

[0013] Further, the step S2 includes: a step S21 of performing gelation treatment on the aluminum-rich liquid and the silicon-rich liquid to obtain a first gel; and a step S22 of sequentially performing aging treatment and hydrothermal crystallization treatment on the first gel and the seed crystal to obtain the 13X molecular sieve; wherein the first gel contains SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of SiO2 to Al2O3 is 0.5-6.0:1, and the molar ratio of Na2O, H2O to SiO2 is 0.5-6.0:10-100:1; the mass ratio of the seed crystal to the first gel is preferably 5-20:100; and / or, the temperature for the aging treatment is 20-100°C, and the time for the aging treatment is 0.1-24 h; and / or, the temperature for the hydrothermal crystallization treatment is 60-105°C, and the time for the hydrothermal crystallization treatment is 0.1-36 h.

[0014] Further, the preparation method further comprises a preparation process of the seed crystal, the preparation process comprising: stirring and mixing raw materials comprising an aluminum source, a second silicon source and water to obtain a second gel; adjusting the pH value of the second gel to 8.5-12.5 and then performing two-stage hydrothermal crystallization treatment to obtain the seed crystal; wherein the stirring and mixing rate is 200-800 rpm; and / or the stirring and mixing temperature is 20-100℃; and / or the stirring and mixing time is 0.1-24 h; preferably, the pH value of the second gel is 11.8-12.2; preferably, the second silicon source is selected from any one or more of silica sol, tetraethyl orthosilicate and silicon powder; preferably, the aluminum source is selected from any one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate and aluminum nitrate; preferably, the two-stage hydrothermal crystallization treatment comprises a first-stage hydrothermal crystallization treatment and a second-stage hydrothermal crystallization treatment, wherein the first-stage hydrothermal crystallization treatment temperature is 20-60℃; and / or the first-stage hydrothermal crystallization treatment time is 4-24 h; preferably, the second-stage hydrothermal crystallization treatment temperature is 80-120℃; and / or the second-stage hydrothermal crystallization treatment time is 6-48 h; further preferably, the first-stage hydrothermal crystallization treatment temperature is 35-45℃, and / or the first-stage hydrothermal crystallization treatment time is 11-13 h; the second-stage hydrothermal crystallization treatment temperature is 90-100℃; and / or the second-stage hydrothermal crystallization treatment time is 22-26 h; the second-stage hydrothermal crystallization treatment temperature is 50-60℃ higher than the first-stage hydrothermal crystallization treatment temperature.

[0015] Further, the preparation method further comprises a pretreatment process of the waste molecular sieve, the pretreatment process comprising: performing sintering treatment on a mixture comprising the waste molecular sieve and a sodium salt to obtain a sintered product; sequentially performing aluminum dissolution treatment and solid-liquid separation on the sintered product using an acidic solution to obtain an aluminum-rich liquid and a residue; sequentially performing silicon dissolution treatment and solid-liquid separation on the residue using an alkaline solution to obtain a silicon-rich liquid; wherein the mass ratio of the waste molecular sieve to the sodium salt is 1:0.5-5; and / or the sintering treatment temperature is 550-800℃; and / or the sintering treatment time is 60-120 min; and / or the acidic solution is a monobasic acid solution, and the mass fraction of the monobasic acid solution is 10-35%, preferably the monobasic acid is hydrochloric acid and / or nitric acid; and / or the alkaline solution comprises a monobasic alkali and water, and the mass ratio of the residue, the monobasic alkali and water is 1.5-100:40-60:50-400; and / or the monobasic alkali is NaOH and / or KOH; preferably, the waste molecular sieve is selected from any one or more of waste HZSM-5 molecular sieve catalyst, waste MTO catalyst, fly ash, waste FCC catalyst and waste VOC adsorbent; and the sodium salt is Na2SO4 and / or NaCO3.

[0016] According to another aspect of the present application, a core-shell structure cracking reaction catalyst is provided, which is prepared by the aforementioned preparation method.

[0017] By applying the technical solution of the present application, the steps S3 and S4 of the present application optimize the structure of the 13X molecular sieve, forming a core-shell structure 13X molecular sieve with the 13X molecular sieve as the core, the nickel nanoparticles as the intermediate layer, and the titanium-silicon molecular sieve as the shell. In this process, the 13X molecular sieve is sequentially subjected to first impregnation treatment and second impregnation treatment, which can sequentially form a nickel nanoparticle intermediate layer and a titanium-silicon molecular sieve shell on the surface of the 13X molecular sieve, forming a gradient structure, which helps to improve the mechanical strength and thermal stability of the molecular sieve. And in this process, the structure of the 13X molecular sieve is greatly optimized, so that the obtained core-shell structure 13X molecular sieve has a certain range of specific surface area and porosity parameters. Therefore, the core-shell structure cracking reaction catalyst prepared from the core-shell structure 13X molecular sieve has excellent cracking reaction catalytic activity, and the application of the core-shell structure cracking reaction catalyst in the cracking reaction helps to improve the reaction efficiency of the cracking reaction. In addition, the 13X molecular sieve prepared in steps S1 and S2 of the present application with waste catalyst as raw material realizes the utilization of waste on the one hand, reduces the cost of preparation of 13X molecular sieve, on the other hand, the 13X molecular sieve prepared by the method of the present application has the characteristics of high silicon-aluminum ratio, large pore volume and specific surface area, regular morphology, etc., thereby helping to improve the silicon source utilization rate of the 13X molecular sieve, providing more catalytically active sites for the cracking reaction catalytic process, and improving the flow and diffusion performance of the reactants in the molecular sieve, thereby improving the reaction efficiency and reaction effect of the cracking reaction catalysis of petroleum and other materials. DETAILED DESCRIPTION

[0018] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0019] As analyzed in the background art of the present application, there is a problem of low cracking reaction efficiency in the prior art. In order to solve this problem, the present application provides a core-shell structure cracking reaction catalyst and a preparation method thereof.

[0020] In an exemplary embodiment of the present application, a preparation method of a core-shell structure cracking reaction catalyst is provided, which comprises the following steps: step S1, sequentially subjecting waste molecular sieve to aluminum dissolution treatment and silicon dissolution treatment to obtain an aluminum-rich liquid and a silicon-rich liquid; step S2, sequentially subjecting raw materials comprising the aluminum-rich liquid, the silicon-rich liquid and seeds to gelation treatment, aging treatment and hydrothermal crystallization treatment to obtain 13X molecular sieve; step S3, sequentially subjecting the 13X molecular sieve to first impregnation treatment and second impregnation treatment in a silanization reagent solution and a nickel-containing solution to obtain nickel-modified 13X molecular sieve; step S4, sequentially subjecting the nickel-modified 13X molecular sieve to first hydrothermal reaction and calcination treatment in a titanium silicalite precursor solution to obtain core-shell structure 13X molecular sieve; and step S5, mixing and stirring the core-shell structure 13X molecular sieve with a platinum precursor solution, and then sequentially subjecting to solid-liquid separation, drying, pre-calcination treatment and first calcination treatment to obtain the core-shell structure cracking reaction catalyst.

[0021] Steps S3 and S4 of the present application optimize the structure of the 13X molecular sieve to form core-shell structure 13X molecular sieve with the 13X molecular sieve as the core, the nickel nanoparticles as the intermediate layer and the titanium silicalite as the outer shell. In this process, the 13X molecular sieve is sequentially subjected to first impregnation treatment and second impregnation treatment, which can sequentially form the intermediate layer of nickel nanoparticles and the outer shell of titanium silicalite on the surface of the 13X molecular sieve to form a gradient structure, which helps to improve the mechanical strength and thermal stability of the molecular sieve. In this process, the structure of the 13X molecular sieve is greatly optimized, so that the obtained core-shell structure 13X molecular sieve has a certain range of specific surface area and porosity parameters. Therefore, the core-shell structure cracking reaction catalyst prepared from the core-shell structure 13X molecular sieve has excellent cracking reaction catalytic activity, and the application of the core-shell structure cracking reaction catalyst in the cracking reaction helps to improve the reaction efficiency of the cracking reaction. In addition, the 13X molecular sieve prepared in steps S1 and S2 of the present application using waste catalyst as raw material not only realizes waste utilization and reduces the cost of preparation of 13X molecular sieve, but also has the characteristics of high silicon-aluminum ratio, large pore volume and specific surface area, and regular morphology, which helps to improve the silicon source utilization rate of the 13X molecular sieve, provides more catalytically active sites for the cracking reaction catalytic process, and improves the flow and diffusion performance of the reactants in the molecular sieve, thereby improving the reaction efficiency and reaction effect of the cracking reaction catalysis of petroleum and other materials.

[0022] In an embodiment of the present application, in the step S3, the first impregnation treatment is performed for 8-24 hours, and / or the second impregnation treatment is performed for 24-48 hours; preferably, the molar concentration of the silane reagent solution is 0.05-0.2 mol / L, and / or the molar concentration of the nickel-containing solution is 0.05-0.2 mol / L; preferably, the mass of the 13X molecular sieve to the volume of the silane reagent solution is 400-600:1 g / L; and / or, the mass of the 13X molecular sieve to the volume of the nickel-containing solution is 400-600:1 g / L; preferably, the nickel-containing solution is selected from a nickel nitrate solution and / or a nickel sulfate solution; preferably, the silane reagent is selected from any one or more of 3-aminopropyltriethoxysilane, tetraethoxysilane and tetramethoxysilane; preferably, the step S3 further comprises: performing a third calcination on the 13X molecular sieve obtained after the second impregnation treatment to obtain a nickel-modified 13X molecular sieve coated with a layer of nickel nanoparticles; and / or, the third calcination is performed in a hydrogen atmosphere at a temperature of 500-600°C for 2-4 hours.

[0023] Preferably, the time of the first impregnation treatment, the time of the second impregnation treatment, the molar concentration of the silane reagent solution and the molar concentration of the nickel-containing solution are controlled within the above ranges, which helps to control the quality of the nickel nanoparticles formed finally and improve the impregnation effect of the silane reagent solution and the nickel-containing solution on the 13X molecular sieve; preferably, the types of the nickel-containing solution and the silane reagent are controlled within the above ranges, which helps to enrich the selectivity of the nickel-containing solution and the silane reagent.

[0024] In the third calcination, the nickel compounds attached to the surface of the 13X molecular sieve are decomposed at high temperature to form nickel oxide, and the hydrogen gas reduces the nickel oxide to nickel nanoparticles; preferably, the temperature and the time of the third calcination are controlled within the above ranges, which helps to improve the efficiency of forming the nickel nanoparticles.

[0025] In an embodiment of the present application, in the step S4, the temperature of the first hydrothermal reaction is 150-200°C, the time of the first hydrothermal reaction is 12-24h; and / or the temperature of the calcination treatment is 450-550°C, the time of the calcination treatment is 4-8h; the titanium-silicon molecular sieve precursor solution comprises a first silicon source, a titanium source, a template agent, a fluorine complex and water, wherein the first silicon source, the titanium source, the template agent, the fluorine complex and the water are mixed according to a molar ratio of 1:0.04-0.1:0.1-0.3:0.03-0.06:20-50; and / or the ratio of the mass of the nickel-modified 13X molecular sieve to the volume of the titanium-silicon molecular sieve precursor solution is 400-600:1g / L; preferably the first silicon source is selected from any one or more of SiO2, Na2SiO3 and Si(OC2H5)4; preferably the titanium source is selected from any one or more of TiO2, TiCl4 and Na2TiO3; preferably the fluorine complex is selected from any one or more of sodium hexafluorophosphate, sodium hexafluoroacetyl acetonate and ammonium fluoride; and preferably the template agent is an organic amine and / or a quaternary ammonium salt.

[0026] Preferably, the temperature and time of the first hydrothermal reaction are controlled within the above ranges, which helps to improve the interaction between the titanium-silicon molecular sieve precursor and the nickel-modified 13X molecular sieve; preferably, the temperature and time of the calcination treatment are controlled within the above ranges, which helps to improve the structural integrity of the finally formed core-shell structure 13X molecular sieve; preferably, the molar ratio of the first silicon source, the titanium source, the template agent, the fluorine complex and the water is controlled within the above ranges, which helps to improve the uniformity of the pore size of the core-shell structure 13X molecular sieve; and preferably, the types of the silicon source, the titanium source, the template agent and the fluorine complex are controlled within the above ranges, which helps to improve the synergistic effect between the components, so that the coating layer formed on the surface of the 13X molecular sieve has higher catalytic activity and stability.

[0027] In an embodiment of the present application, in the step S5, the time of the mixing and stirring is 12-36h; the weight concentration of the platinum precursor solution is 2-3g / L; preferably the platinum precursor solution is hexachloroplatinic acid dihydrate; the ratio of the mass of the core-shell structure 13X molecular sieve to the volume of the platinum precursor solution is 1:5g / L; the atmosphere of the pre-calcination treatment is an inert gas, the temperature of the pre-calcination treatment is 450-550°C, and the time of the pre-calcination treatment is 1-3h; the temperature of the first calcination treatment is 700-900°C, the time of the first calcination treatment is 3-5h, and the atmosphere of the first calcination treatment is air; and the temperature of the drying is 90-130°C, and the time of the drying is 8-16h.

[0028] To control the amount of platinum salt attached to the core-shell structure 13X molecular sieve and improve the infiltration effect of the platinum precursor solution on the core-shell structure 13X molecular sieve, thereby improving the catalytic efficiency of the core-shell structure cracking reaction catalyst, it is preferred to control the mixing and stirring time and the molar concentration of the platinum precursor solution within the above range. It is preferred to control the temperature, time and atmosphere of the pre-calcination treatment and the first calcination treatment within the above range, which helps to improve the efficiency of the formation of platinum salt on the core-shell structure 13X molecular sieve into metal platinum oxide or platinum metal; it is preferred to control the temperature and time of drying within the above range, which helps to remove moisture on the core-shell structure 13X molecular sieve.

[0029] In an embodiment of the present application, in the above step S2, the 13X molecular sieve contains silicon and aluminum elements, and the molar ratio of silicon and aluminum elements is 2.2-2.9:1; and / or the pore volume of the 13X molecular sieve is 0.3-0.5 cm 3 / g, and / or the specific surface area of the 13X molecular sieve is 700-950 m 2 / g.

[0030] It is preferred to prepare the 13X molecular sieve obtained by the steps S1 and S2 of the present application to have the above properties. Among them, it is preferred that the molar ratio of silicon and aluminum elements is within the above range, which helps to improve the utilization rate of silicon source in the 13X molecular sieve; it is preferred that the pore volume and specific surface area of the 13X molecular sieve are within the above range, which helps to provide more catalytically active sites for the cracking reaction catalytic process and is beneficial to improve the flow and diffusion performance of reactant molecules inside the molecular sieve.

[0031] To improve the formation and stability of the 13X molecular sieve framework structure, in an embodiment of the present application, it is preferred that the above seed contains SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of SiO2 to Al2O3 is 0.01-2.5:1, and the molar ratio of Na2O, H2O to SiO2 is 0.01-4.0:1.0-40.0:1.

[0032] To further promote the structure of 13X molecular sieve to be generated smoothly, in an embodiment of the present application, preferably, the step S2 comprises: step S21, subjecting the aluminum-rich liquid to gelation treatment with the silicon-rich liquid to obtain a first gel; step S22, subjecting the first gel and the seed crystal to aging treatment and hydrothermal crystallization treatment in sequence to obtain the 13X molecular sieve; wherein the first gel comprises SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of SiO2 to Al2O3 is 0.5-6.0:1, and the molar ratio of Na2O, H2O to SiO2 is 0.5-6.0:10-100:1; preferably, the mass ratio of the seed crystal to the first gel is 5-20:100; and / or the temperature of the aging treatment is 20-100°C, and the time of the aging treatment is 0.1-24h; and / or the temperature of the hydrothermal crystallization treatment is 60-105°C, and the time of the hydrothermal crystallization treatment is 0.1-36h.

[0033] In addition, preferably, the aging process is carried out under stirring.

[0034] To promote the formation of 13X molecular sieve crystals, in an embodiment of the present application, preferably, the preparation method further comprises a preparation process of the seed crystal, which comprises: stirring and mixing raw materials comprising an aluminum source, a second silicon source and water to obtain a second gel; adjusting the pH value of the second gel to 8.5-12.5 and then subjecting to two-stage hydrothermal crystallization treatment to obtain the seed crystal; wherein the stirring and mixing rate is 200-800rpm, and / or the stirring and mixing temperature is 20-100°C, and / or the stirring and mixing time is 0.1-24h; preferably, the pH value of the second gel is 11.8-12.2; further preferably, the pH value of the above-mentioned second gel is 12. Preferably, the second silicon source is selected from any one or more of silica sol, tetraethyl orthosilicate and silicon powder; and preferably, the aluminum source is selected from any one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate and aluminum nitrate.

[0035] In order to improve the crystallization degree of the 13X molecular sieve, preferably, the two-stage hydrothermal crystallization treatment includes a first-stage hydrothermal crystallization treatment and a second-stage hydrothermal crystallization treatment, wherein the temperature of the first-stage hydrothermal crystallization treatment is 20-60°C, and / or the time of the first-stage hydrothermal crystallization treatment is 4-24 h; preferably, the temperature of the second-stage hydrothermal crystallization treatment is 80-120°C, and / or the time of the second-stage hydrothermal crystallization treatment is 6-48 h; further, preferably, the temperature of the first-stage hydrothermal crystallization treatment is 35-45°C, and / or the time of the first-stage hydrothermal crystallization treatment is 11-13 h; the temperature of the second-stage hydrothermal crystallization treatment is 90-100°C, and / or the time of the second-stage hydrothermal crystallization treatment is 22-26 h; the temperature of the second-stage hydrothermal crystallization treatment is 50-60°C higher than the temperature of the first-stage hydrothermal crystallization treatment; further preferably, the temperature of the first-stage hydrothermal crystallization treatment is 40°C, and / or the time of the first-stage hydrothermal crystallization treatment is 12 h; the temperature of the second-stage hydrothermal crystallization treatment is 95°C, and / or the time of the second-stage hydrothermal crystallization treatment is 24 h.

[0036] In addition, in order to further improve the mixing effect of the aluminum source, the silicon source and water, preferably, the specific steps of stirring and mixing the above-mentioned aluminum source, the second silicon source and water include: stirring and mixing the silicon source and water, the temperature of stirring and mixing is 20-60°C, the time of stirring and mixing is 0.1-12 h, the rotating speed of stirring and mixing is 200-800 rpm, to obtain a silicon-containing solution, the concentration of the silicon-containing solution is 28%-99wt%; stirring and mixing the aluminum source and water, the temperature of stirring and mixing is 20-60°C, the time of stirring and mixing is 0.1-12 h, the rotating speed of stirring and mixing is 200-800 rpm, to obtain an aluminum-containing solution, the concentration of the aluminum-containing solution is 28%-99wt%, and stirring and mixing the silicon-containing solution and the aluminum-containing solution to obtain the second gel.

[0037] Preferably, the way of adjusting the pH value of the second gel is to slowly add a solid base or an aqueous base solution into the second gel; preferably, the base is selected from sodium hydroxide and / or potassium hydroxide. Preferably, after the first hydrothermal crystallization treatment in the step S22, the reaction product needs to be filtered and washed to neutral, and then dried at 80-120°C to obtain the 13X molecular sieve without obvious weight loss.

[0038] In order to remove impurities such as water and carbon deposition in the waste molecular sieve, and further reduce the preparation cost of the 13X molecular sieve and increase the pore volume and specific surface area of the 13X molecular sieve, in an embodiment of the present application, the preparation method preferably further comprises a pretreatment process of the waste molecular sieve, and the pretreatment process comprises: sintering a mixture comprising the waste molecular sieve and a sodium salt to obtain a sintered product; sequentially performing aluminum dissolution treatment and solid-liquid separation on the sintered product by using an acidic solution to obtain an aluminum-rich liquid and a residue; sequentially performing silicon dissolution treatment and solid-liquid separation on the residue by using an alkaline solution to obtain a silicon-rich liquid; wherein the mass ratio of the waste molecular sieve to the sodium salt is 1:0.5-5; and / or the sintering temperature is 550-800°C, and / or the sintering time is 60-120 min; and / or the acidic solution is a monobasic acid solution, and the mass fraction of the monobasic acid solution is 10-35%; preferably the monobasic acid is hydrochloric acid and / or nitric acid; and / or the alkaline solution comprises a monobasic alkali and water, and the mass ratio of the residue, the monobasic alkali and the water is 1.5-100:40-60:50-400; and / or the monobasic alkali is NaOH and / or KOH; preferably the waste molecular sieve is selected from any one or more of waste HZSM-5 molecular sieve catalyst, waste MTO catalyst, fly ash, waste FCC catalyst, and waste VOC adsorbent; and the sodium salt is Na2SO4 and / or NaCO3.

[0039] In addition, preferably the size of the waste molecular sieve is less than 200 mesh.

[0040] In another typical embodiment of the present application, a core-shell structure cracking reaction catalyst is provided, which is prepared by the aforementioned preparation method.

[0041] The core-shell structure cracking reaction catalyst prepared by the preparation method of the present application has excellent cracking reaction catalytic activity and stability, and can realize efficient cracking reaction at a lower temperature. The application of the core-shell structure cracking reaction catalyst in the cracking reaction helps to improve the reaction efficiency of the cracking reaction. In addition, the core-shell structure cracking reaction catalyst prepared by the preparation method of the present application can be applied in petroleum cracking, waste plastic treatment and other complex organic conversion reactions, and has wide application potential.

[0042] The beneficial effects of the present application will be further illustrated in combination with the following examples.

[0043] Example 1

[0044] 13X molecular sieve seed preparation: 21.0 g of silica sol (mass fraction 30%) was dissolved in 36.0 g of deionized water, and a silicon-containing solution was obtained after pretreatment at 25°C in a closed reaction kettle for 1 h; 24 g of aluminum sulfate was dissolved in 18.0 g of deionized water, and an aluminum-containing solution was obtained after stirring at 25°C for 1 h; the aluminum-containing solution was slowly added to the silicon-containing solution, and the solution after the addition was stirred at 60°C for 8 h to obtain a gel mixture; 6.74 g of sodium hydroxide was dissolved in 36 g of deionized water to obtain a sodium hydroxide aqueous solution, and the sodium hydroxide aqueous solution was added to the gel mixture to maintain the pH value of the gel mixture at 12 to obtain a second gel; the second gel was placed in a hydrothermal reaction kettle and subjected to two-stage hydrothermal crystallization treatment, the first-stage hydrothermal crystallization treatment was carried out at 40°C for 12 h, and the second-stage hydrothermal crystallization treatment was carried out at 95°C for 24 h to obtain a 13X molecular sieve seed solution; the 13X molecular sieve seed solution was sequentially subjected to filtration, washing, and drying to obtain 13X molecular sieve seeds. The molar ratio of SiO2 to Al2O3 in the 13X molecular sieve seeds was 1.5:1, and the molar ratio of Na2O, H2O to SiO2 was 1.6:32:1.

[0045] 13X molecular sieve preparation: waste Z-5 molecular sieve catalyst and NaCO3 were mixed at a mass ratio of 1:2.5 for sintering treatment, the sintering treatment was carried out at a temperature of 600°C for 100 min, then the sintered product was subjected to aluminum dissolution treatment with 25% hydrochloric acid, and then filtration was performed to obtain an aluminum-rich liquid and a residue; the residue was mixed with NaOH and H2O at a mass ratio of 50:50:200 for silicon dissolution treatment, and then filtration was performed to obtain a silicon-rich liquid; the silicon-rich liquid and the aluminum-rich liquid were mixed to obtain a first gel; the 13X molecular sieve seeds and the first gel were mixed at a mass ratio of 10:100, and then aging treatment and hydrothermal crystallization treatment were sequentially performed, the aging treatment was carried out at a temperature of 50°C for 12 h; the hydrothermal crystallization treatment was carried out at a temperature of 70°C for 24 h, and then drying was performed to obtain 13X molecular sieve. The molar ratio of SiO2 to Al2O3 in the first gel was 3.5:1, the molar ratio of Na2O, H2O to SiO2 was 2.8:80:1, the molar ratio of silicon to aluminum in the 13X molecular sieve was 2.60:1; the pore volume of the 13X molecular sieve was 0.4789 cm 3 / g, and the specific surface area of the 13X molecular sieve was 877.2 m 2 / g.

[0046] Preparation of the core-shell structure 13X molecular sieve: 300 g of the 13X molecular sieve powder described above was put into 500 mL of a 0.2 mol / L solution of 3- aminopropyltriethoxysilane for first impregnation treatment, and the first impregnation treatment was performed for 8 hours; then 300 g of the treated 13X molecular sieve was put into 500 mL of a 0.2 mol / L nickel nitrate solution for second impregnation treatment, and the second impregnation treatment was performed for 24 hours; then the 13X molecular sieve after the second impregnation treatment was subjected to third calcination in a hydrogen atmosphere at 500°C for 2 hours, to obtain a nickel-modified 13X molecular sieve containing a nickel nanoparticle deposition layer. SiO2, TiO2, tetraethylammonium hydroxide, sodium hexafluorophosphate and water were mixed to prepare a titanium silicalite precursor solution, wherein the molar ratio of SiO2, TiO2, organic amine, sodium hexafluorophosphate and water was 1:0.06:0.15:0.04:40; 150 g of the 13X molecular sieve containing the nickel nanoparticle deposition layer was added to 250 mL of the titanium silicalite precursor solution, and after being mixed thoroughly, it was transferred to a reaction kettle for first hydrothermal reaction, and the first hydrothermal reaction was performed at a temperature of 150°C for 12 hours; after the reaction was completed, the solid was taken out and washed with water, and then dried at 110°C for 12 hours; the dried solid was subjected to calcination treatment at a temperature of 450°C for 4 hours, to obtain the core-shell structure 13X molecular sieve.

[0047] Preparation of the core-shell structure cracking reaction catalyst: 1 g of hexachloroplatinic acid dihydrate was dissolved in 500 mL of deionized water to form a platinum precursor solution; 100 g of the core-shell structure 13X molecular sieve was added to the prepared platinum precursor solution, and after being stirred thoroughly for 24 hours using a magnetic stirrer, it was filtered; the filtered core-shell structure 13X molecular sieve was placed in a drying box and dried at 110°C for 12 hours. The dried core-shell structure 13X molecular sieve was placed in a molybdenum cloth furnace and precalcined at 500°C in a nitrogen atmosphere for 2 hours, and then calcined at 800°C in an air atmosphere for 4 hours, to obtain the core-shell structure cracking reaction catalyst.

[0048] Example 2

[0049] The difference from Example 1 is that the preparation of the 13X molecular sieve seed crystal: 1 g of silicon powder is dissolved in 18.0 g of deionized water, and after pretreatment at 25°C in a closed reaction kettle for 1 hour, a silicon-containing solution is obtained; 12 g of aluminum sulfate is dissolved in 18.0 g of deionized water, and stirred at 35°C for 1 h to obtain an aluminum-containing solution; the aluminum-containing solution is slowly added to the silicon-containing solution, and the solution after the completion of the dropwise addition is stirred at 50°C for 6 h to obtain a gel mixture; 2 g of sodium hydroxide is dissolved in 36 g of deionized water to obtain a sodium hydroxide aqueous solution, and the sodium hydroxide aqueous solution is added to the gel mixture, and the pH value of the gel mixture is controlled to maintain at 11.8, to obtain a second gel, which is placed in a hydrothermal reaction kettle for two-stage hydrothermal crystallization treatment, the first-stage hydrothermal crystallization treatment is carried out at a temperature of 50°C for 14 hours, and the second-stage hydrothermal crystallization treatment is carried out at a temperature of 100°C for 18 hours, to obtain a 13X molecular sieve seed crystal solution, which is sequentially filtered, washed and dried to obtain a 13X molecular sieve seed crystal, and finally a core-shell structured cracking reaction catalyst is obtained. The molar ratio of SiO2 to Al2O3 of the 13X molecular sieve seed crystal is 0.6:1, the molar ratio of Na2O, H2O to SiO2 is 3:20:1, the silicon-aluminum ratio of the 13X molecular sieve is 2.40:1; the pore volume of the 13X molecular sieve is 0.4590 cm 3 / g, and the specific surface area of the 13X molecular sieve is 873.2 m 2 / g.

[0050] Example 3

[0051] The difference from Example 1 is that the preparation of the 13X molecular sieve seed crystal: 0.17 g of silicon powder is dissolved in 6 g of deionized water, and after pretreatment at 25°C for 1 h in a closed reaction kettle, a silicon-containing solution is obtained; 12 g of aluminum sulfate is dissolved in 18 g of deionized water, and stirred at 35°C for 1 h to obtain an aluminum-containing solution; the aluminum-containing solution is slowly added to the silicon-containing solution, and the solution after the completion of the dropwise addition is stirred at 100°C for 24 h to obtain a gel mixture; 0.9 g of sodium hydroxide is dissolved in 6 g of deionized water to obtain a sodium hydroxide aqueous solution, and the sodium hydroxide aqueous solution is added to the gel mixture, and the pH value of the gel mixture is controlled to maintain at 12.5, to obtain a second gel, and the second gel is placed in a hydrothermal reaction kettle for two-stage hydrothermal crystallization treatment, the first-stage hydrothermal crystallization treatment is carried out at a temperature of 60°C for 24 h, and the second-stage hydrothermal crystallization treatment is carried out at a temperature of 120°C for 48 h, to obtain a 13X molecular sieve seed crystal solution, which is sequentially filtered, washed and dried to obtain a 13X molecular sieve seed crystal, and finally a core-shell structured cracking reaction catalyst is obtained. The molar ratio of SiO2 to Al2O3 of the 13X molecular sieve seed crystal is 0.1:1, the molar ratio of Na2O, H2O to SiO2 is 4:1:1, the silicon-aluminum ratio of the 13X molecular sieve is 2.23:1; the pore volume of the 13X molecular sieve is 0.3693 cm 3 / g, and the specific surface area of the 13X molecular sieve is 801.2 m 2 / g.

[0052] Example 4

[0053] The difference from example 1 is that the preparation of 13X molecular sieve seeds: 14.65g of tetraethyl orthosilicate is dissolved in 36.0g of deionized water, and after pretreatment at 25℃ for 1h in a closed reaction kettle, a silicon-containing solution is obtained; 12g of aluminum sulfate is dissolved in 18.0g of deionized water, and after stirring at 35℃ for 1h, an aluminum-containing solution is obtained; the aluminum-containing solution is slowly added to the silicon-containing solution, and the solution after the addition is stirred at 20℃ for 0.1h to obtain a gel mixture; 0.56g of sodium hydroxide is dissolved in 6g of deionized water to obtain a sodium hydroxide aqueous solution, and the sodium hydroxide aqueous solution is added to the gel mixture to control the pH value of the gel mixture to maintain at 8.5, to obtain a second gel; the second gel is placed in a hydrothermal reaction kettle, and two-stage hydrothermal crystallization treatment is carried out; the first-stage hydrothermal crystallization treatment is carried out at a temperature of 20℃ for 4h, and the second-stage hydrothermal crystallization treatment is carried out at a temperature of 80℃ for 6h to obtain a 13X molecular sieve seed solution; the 13X molecular sieve seed solution is filtered, washed and dried in sequence to obtain 13X molecular sieve seeds, and finally a core-shell structured cracking reaction catalyst is obtained. The molar ratio of SiO2 to Al2O3 of the 13X molecular sieve seeds is 2.5:1, the molar ratio of Na2O, H2O to SiO2 is 0.01:40:1, and the silicon-aluminum ratio of the 13X molecular sieve is 2.87:1; the pore volume of the 13X molecular sieve is 0.3916cm 3 / g, and the specific surface area of the 13X molecular sieve is 821.1m 2 / g.

[0054] Example 5

[0055] The difference from example 1 is that the first impregnation treatment time is 24h, and the second impregnation treatment time is 48h; the molar concentration of the silanization reagent solution is 0.05mol / L, and the molar concentration of the nickel-containing solution is 0.05mol / L, and finally a core-shell structured cracking reaction catalyst is obtained.

[0056] Example 6

[0057] The difference from example 1 is that the first impregnation treatment time is 7h, and the second impregnation treatment time is 20h; the molar concentration of the silanization reagent solution is 0.04mol / L, and the molar concentration of the nickel-containing solution is 0.04mol / L, and finally a core-shell structured cracking reaction catalyst is obtained.

[0058] Example 7

[0059] The difference from example 1 is that the third calcination temperature is 600℃, and the third calcination time is 4h, and finally a core-shell structured cracking reaction catalyst is obtained.

[0060] Example 8

[0061] The difference from example 1 is that the temperature of the third calcination is 400℃, and the time of the third calcination is 1h, and finally a core-shell structure cracking reaction catalyst is obtained.

[0062] Example 9

[0063] The difference from example 1 is that the temperature of the first hydrothermal reaction is 200℃, and the time of the first hydrothermal reaction is 24h; the temperature of the calcination treatment is 550℃, and the time of the calcination treatment is 8h, and finally a core-shell structure cracking reaction catalyst is obtained.

[0064] Example 10

[0065] The difference from example 1 is that the temperature of the first hydrothermal reaction is 140℃, and the time of the first hydrothermal reaction is 10h; the temperature of the calcination treatment is 400℃, and the time of the calcination treatment is 3h, and finally a core-shell structure cracking reaction catalyst is obtained.

[0066] Example 11

[0067] The difference from example 1 is that the molar ratio of SiO2, TiO2, tetraethylammonium hydroxide, sodium hexafluorophosphate and water is 1:0.04:0.1:0.03:20, and finally a core-shell structure cracking reaction catalyst is obtained.

[0068] Example 12

[0069] The difference from example 1 is that the molar ratio of SiO2, TiO2, tetraethylammonium hydroxide, sodium hexafluorophosphate and water is 1:0.1:0.3:0.06:50, and finally a core-shell structure cracking reaction catalyst is obtained.

[0070] Example 13

[0071] The difference from example 1 is that the molar ratio of SiO2, TiO2, tetraethylammonium hydroxide, sodium hexafluorophosphate and water is 1:0.2:0.4:0.07:60, and finally a core-shell structure cracking reaction catalyst is obtained.

[0072] Example 14

[0073] The difference from example 1 is that the mass concentration of the platinum precursor solution is 3g / L, and finally a core-shell structure cracking reaction catalyst is obtained.

[0074] Example 15

[0075] The difference from example 1 is that the mass concentration of the platinum precursor solution is 1g / L, and finally a core-shell structure cracking reaction catalyst is obtained.

[0076] Comparative example 1

[0077] The difference from Example 1 is that 13X molecular sieve is directly used in the preparation of the cracking reaction catalyst, and finally the cracking reaction catalyst is obtained.

[0078] Test method

[0079] Cracking reaction catalytic treatment process

[0080] The cracking reaction catalysts obtained in the above examples and comparative examples are used in naphtha steam cracking reaction, and the specific reaction conditions are as follows: the reaction temperature is 550 DEG C, the reaction pressure is 80 KPa, the reaction time is set to 2 hours, and the mass ratio of water to oil is 0.6. The yield of triene (ethylene, propylene, butadiene) and the selectivity of triene conversion are shown in Table 1.

[0081] Table 1

[0082]

[0083]

[0084] From the above description, it can be seen that the above examples of the present application achieve the following technical effects:

[0085] The steps S3 and S4 of the present application optimize the structure of the 13X molecular sieve, form a core-shell structure 13X molecular sieve with the 13X molecular sieve as the core, the nickel nanoparticles as the intermediate layer, and the titanium-silicon molecular sieve as the shell, and in the process, the 13X molecular sieve is sequentially subjected to first and second impregnation treatments, which can sequentially form a nickel nanoparticle intermediate layer and a titanium-silicon molecular sieve shell on the surface of the 13X molecular sieve, forming a gradient structure, which helps to improve the mechanical strength and thermal stability of the molecular sieve. And in the process, the structure of the 13X molecular sieve is greatly optimized, so that the obtained core-shell structure 13X molecular sieve has a certain range of specific surface area and porosity parameters. Therefore, the core-shell structure cracking reaction catalyst prepared from the core-shell structure 13X molecular sieve has excellent cracking reaction catalytic activity, and the application of the core-shell structure cracking reaction catalyst in the cracking reaction helps to improve the reaction efficiency of the cracking reaction. In addition, the 13X molecular sieve prepared in steps S1 and S2 of the present application using waste catalyst as raw material not only realizes waste utilization and reduces the cost of 13X molecular sieve preparation, but also has the characteristics of high silicon-aluminum ratio, large pore volume and specific surface area, and regular morphology, thereby helping to improve the silicon source utilization rate of the 13X molecular sieve, providing more catalytically active sites for the cracking reaction catalytic process, and improving the flow and diffusion performance of the reactants in the molecular sieve, thereby improving the reaction efficiency and reaction effect of the cracking reaction catalysis of petroleum and other materials.

[0086] The above merely describes the preferred embodiments of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a core-shell structured cracking reaction catalyst, characterized in that, The preparation method includes the following steps: Step S1: The waste molecular sieve is subjected to aluminum dissolution treatment and silicon dissolution treatment in sequence to obtain aluminum-rich liquid and silicon-rich liquid. Step S21: The aluminum-rich liquid and the silicon-rich liquid are subjected to gelation treatment to obtain a first gel; Step S22: The first gel and the seed crystal are subjected to aging treatment and hydrothermal crystallization treatment in sequence to obtain 13X molecular sieve; wherein, the preparation process of the seed crystal includes: stirring and mixing raw materials including aluminum source, second silicon source and water to obtain second gel; adjusting the pH value of the second gel to 8.5~12.5 and then performing two-stage hydrothermal crystallization treatment to obtain the seed crystal; Step S3: The 13X molecular sieve is subjected to a first impregnation treatment and a second impregnation treatment in a silanizing reagent solution and a nickel-containing solution in sequence to obtain nickel-modified 13X molecular sieve; Step S4 involves sequentially subjecting the nickel-modified 13X molecular sieve and the titanium-silicon molecular sieve precursor solution to a first hydrothermal reaction and calcination treatment to obtain a core-shell structured 13X molecular sieve; and Step S5: The core-shell structured 13X molecular sieve is mixed with a platinum precursor solution and then subjected to solid-liquid separation, drying, pre-calcination, and first calcination to obtain a core-shell structured cracking reaction catalyst.

2. The preparation method according to claim 1, characterized in that, In step S3: the first immersion treatment lasts for 8 to 24 hours; and / or the second immersion treatment lasts for 24 to 48 hours.

3. The preparation method according to claim 1, characterized in that, The molar concentration of the silanizing reagent solution is 0.05~0.2 mol / L; and / or, the molar concentration of the nickel-containing solution is 0.05~0.2 mol / L.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the 13X molecular sieve to the volume ratio of the silanizing reagent solution is 400~600:1 g / L; and / or, the mass ratio of the 13X molecular sieve to the volume ratio of the nickel-containing solution is 400~600:1 g / L.

5. The preparation method according to claim 1, characterized in that, The nickel-containing solution is a nickel nitrate solution and / or a nickel sulfate solution.

6. The preparation method according to claim 1, characterized in that, The silanizing agent is selected from any one or more of 3-aminopropyltriethoxysilane, tetraethoxysilane, and tetramethoxysilane.

7. The preparation method according to claim 1, characterized in that, Step S3 further includes: subjecting the 13X molecular sieve obtained by the second impregnation treatment to a third calcination to obtain the nickel-modified 13X molecular sieve coated with a nickel nanoparticle layer.

8. The preparation method according to claim 7, characterized in that, The atmosphere for the third calcination is hydrogen, the temperature for the third calcination is 500~600℃, and the time for the third calcination is 2~4h.

9. The preparation method according to claim 1, characterized in that, In step S4 The temperature of the first hydrothermal reaction is 150~200℃, and the time of the first hydrothermal reaction is 12~24h; And / or, the calcination temperature is 450~550℃, and the calcination time is 4~8h; The titanium-silicon molecular sieve precursor solution comprises a first silicon source, a titanium source, a template agent, a fluorine complex, and water, wherein the first silicon source, the titanium source, the template agent, the fluorine complex, and the water are mixed in a molar ratio of 1:0.04~0.1:0.1~0.3:0.03~0.06:20~50. And / or, the mass ratio of the nickel-modified 13X molecular sieve to the volume ratio of the titanium-silicon molecular sieve precursor solution is 400~600:1 g / L.

10. The preparation method according to claim 9, characterized in that, The first silicon source is selected from any one or more of SiO2, Na2SiO3 and Si(OC2H5)4.

11. The preparation method according to claim 9, characterized in that, The titanium source is selected from any one or more of TiO2, TiCl4 and Na2TiO3.

12. The preparation method according to claim 9, characterized in that, The fluorine complex is selected from any one or more of sodium hexafluorophosphate, sodium hexafluoroacetylacetonate, and ammonium fluoride.

13. The preparation method according to claim 9, characterized in that, The template agent is an organic amine.

14. The preparation method according to claim 1, characterized in that, In step S5 The mixing process involves stirring for 12 to 36 hours. And / or, the atmosphere of the pre-calcination treatment is an inert gas, and / or, the temperature of the pre-calcination treatment is 450~550℃; and / or, the time of the pre-calcination treatment is 1~3h; And / or, the temperature of the first calcination treatment is 700~900℃; and / or, the time of the first calcination treatment is 3~5h; and / or, the atmosphere of the first calcination treatment is air; And / or, the drying temperature is 90~130℃, and the drying time is 8~16h.

15. The preparation method according to claim 1, characterized in that, The mass concentration of the platinum precursor solution is 2~3 g / L.

16. The preparation method according to claim 1, characterized in that, The platinum precursor solution is a hexachloroplatinic acid dihydrate solution.

17. The preparation method according to claim 1, characterized in that, The mass ratio of the core-shell structured 13X molecular sieve to the volume ratio of the platinum precursor solution is 1:5 g / L.

18. The preparation method according to claim 1, characterized in that, In step S22, the 13X molecular sieve contains silicon and aluminum, with a molar ratio of silicon to aluminum of 2.2 to 2.9:1; and / or, the pore volume of the 13X molecular sieve is 0.3 to 0.5 cm³. 3 / g; and / or, the specific surface area of ​​the 13X molecular sieve is 700~950m². 2 / g.

19. The preparation method according to claim 1, characterized in that, The seed crystal contains SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of SiO2 to Al2O3 is 0.01~2.5:1, and the molar ratio of Na2O, H2O and SiO2 is 0.01~4.0:1.0~40.0:

1.

20. The preparation method according to claim 1, characterized in that, The first gel comprises SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of SiO2 to Al2O3 is 0.5~6.0:1, and the molar ratio of Na2O, H2O and SiO2 is 0.5~6.0:10~100:

1.

21. The preparation method according to claim 1, characterized in that, The mass ratio of the seed crystal to the first gel is 5~20:100; and / or, the aging treatment temperature is 20~100℃, and the aging treatment time is 0.1~24h; and / or, the hydrothermal crystallization treatment temperature after the aging treatment is 60~105℃, and the hydrothermal crystallization treatment time after the aging treatment is 0.1~36h.

22. The preparation method according to claim 1, characterized in that, The stirring and mixing rate is 200~800 rpm; and / or the stirring and mixing temperature is 20~100℃; and / or the stirring and mixing time is 0.1~24h.

23. The preparation method according to claim 1, characterized in that, Adjust the pH of the second gel to 11.8~12.

2.

24. The preparation method according to claim 1, characterized in that, The second silicon source is selected from any one or more of silica sol, tetraethyl orthosilicate, and silicon powder.

25. The preparation method according to claim 1, characterized in that, The aluminum source is selected from any one or more of sodium aluminate, boehmite, aluminum sulfate, and aluminum nitrate.

26. The preparation method according to claim 1, characterized in that, The two-stage hydrothermal crystallization process includes a first-stage hydrothermal crystallization process and a second-stage hydrothermal crystallization process, wherein, The temperature of the first stage of hydrothermal crystallization treatment is 20~60℃; and / or the time of the first stage of hydrothermal crystallization treatment is 4~24h; The temperature of the second stage of hydrothermal crystallization treatment is 80~120℃; and / or the time of the second stage of hydrothermal crystallization treatment is 6~48h.

27. The preparation method according to claim 26, characterized in that, The temperature of the first stage of hydrothermal crystallization treatment is 35~45℃, and / or the time of the first stage of hydrothermal crystallization treatment is 11~13h; The temperature of the second stage of hydrothermal crystallization treatment is 90~100℃; and / or the time of the second stage of hydrothermal crystallization treatment is 22~26h; The temperature of the second stage of hydrothermal crystallization treatment is 50-60°C higher than that of the first stage of hydrothermal crystallization treatment.

28. A core-shell structured cracking reaction catalyst, characterized in that, The core-shell structured cracking catalyst is prepared by the preparation method according to any one of claims 1 to 27.

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