Process for the preparation of cracking catalyst from spent catalyst, cracking catalyst and use thereof

Abstract

The application provides a method for preparing a cracking catalyst from waste catalyst, a cracking catalyst and application thereof. The method comprises the following steps: dissolving aluminum and silicon in the waste catalyst, adding seeds, aging, crystallizing, mixing 13X molecular sieve with a platinum precursor solution, filtering, obtaining a catalyst precursor, pre-calcining under an inert gas atmosphere, and then calcining under an air atmosphere to obtain a cracking catalyst; wherein the waste catalyst comprises one or more of waste Z-5 molecular sieve catalyst, waste MTO catalyst, waste molecular sieve adsorbent, fly ash, waste FCC catalyst and waste VOC adsorbent; the calcining temperature is greater than the pre-calcining temperature, and the temperature difference is 250-350 DEG C. The application utilizes waste catalyst resources to prepare 13X molecular sieve, and then prepares a new type of high-efficiency cracking catalyst through two-step calcining, which not only can reduce the generation of industrial waste, but also helps to reduce the production cost of the catalyst and improve the green sustainability of the cracking process.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, and more specifically, to a method for preparing cracking catalysts from spent catalysts, the cracking catalysts themselves, and their applications. Background Technology

[0002] Cracking is a crucial process in the oil refining and petrochemical industries. It converts heavier hydrocarbon feedstocks into lighter, more economically valuable compounds, such as petroleum fuels, olefins, and aromatics. The key to cracking lies in using highly efficient catalysts to accelerate the reaction.

[0003] Traditional cracking catalysts typically include acidic materials, such as zeolite molecular sieves, which can improve reaction selectivity and conversion. However, over time, the catalysts can become deactivated due to carbon buildup and metal deposition, requiring replacement, leading to production interruptions and the generation of catalyst waste.

[0004] In addition, due to the limited availability of fossil fuel resources and increasing environmental pressures, finding and developing more efficient, economical, and environmentally friendly cracking catalysts has become an important issue in this field. Summary of the Invention

[0005] The main objective of this invention is to provide a method for preparing cracking catalysts from waste catalysts, the cracking catalysts themselves, and their applications, in order to solve the problems of high cost and environmental unfriendliness of existing cracking catalysts.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a cracking catalyst from spent catalyst is provided, comprising the following steps: Step S1, subjecting the spent catalyst to aluminum and silicon dissolution treatments to obtain a silicon-rich liquid and an aluminum-rich liquid, mixing the silicon-rich liquid and the aluminum-rich liquid to obtain a gel-like mother liquor; adding seed crystals to the gel-like mother liquor, and then sequentially performing aging and crystallization treatments, and drying to obtain 13X molecular sieve; Step S2, mixing the 13X molecular sieve with a platinum precursor solution, stirring for 12–36 hours, then filtering, and the filter cake is heated to 90– The catalyst precursor is obtained by drying at 130℃ for 8–16 hours; in step S3, the catalyst precursor is pre-calcined in an inert gas atmosphere to obtain a pre-calcined product; in step S4, the pre-calcined product is calcined in an air atmosphere to obtain a cracking catalyst; wherein, the waste catalyst includes one or more of the following: waste Z-5 molecular sieve catalyst, waste MTO catalyst, waste molecular sieve adsorbent, fly ash, waste FCC catalyst, and waste VOC adsorbent; wherein, the calcination temperature is higher than the pre-calcination temperature, and the temperature difference is 250–350℃.

[0007] Furthermore, in step S3, the pre-calcination temperature is 450–550°C, and the time is 1–3 hours.

[0008] Furthermore, in step S4, the roasting temperature is 700–900°C, and the time is 3–5 hours.

[0009] Further, in step S1, dissolving aluminum includes: mixing the waste catalyst with NaCO3, calcining at 550-800℃ for 60-120 min, then dissolving the calcined product with a monobasic acid, filtering, and obtaining an aluminum-rich liquid and aluminum-dissolving filter residue; preferably, the mass ratio of the waste catalyst to NaCO3 is 1:(0.5-1:5); and / or the mass concentration of the monobasic acid is 10-35%; dissolving silicon includes: mixing the aluminum-dissolving filter residue with NaOH and H2O, filtering, and obtaining a silicon-rich liquid; preferably, the mass ratio of the aluminum-dissolving filter residue to NaOH and H2O is (2-100):(40-60):(50-400).

[0010] Further, in step S1, the molar ratio of each component in the gel-like mother liquor is: SiO2 / Al2O3 = (0.5~6.0):1, Na2O / SiO2 = (0.5~6.0):1, H2O / SiO2 = (10~100):1; preferably, the amount of seed crystals added accounts for 5~20 wt% of the gel-like mother liquor by weight percentage.

[0011] Further, in step S1, aging is carried out under stirring conditions at a temperature of 20–100°C for a time of 0.1–24 h; and / or crystallization is carried out at a temperature of 60–105°C for a time of 0.1–36 h.

[0012] Furthermore, the 13X molecular sieve has a silica-to-alumina ratio of 2.2–2.9 and a pore volume of 0.3–0.5 cm³. 3 / g, specific surface area of ​​700-950m² 2 / g.

[0013] Furthermore, the molar ratios of the components in the seed crystal are: SiO2 / Al2O3 = (0.1~2.5):1, Na2O / SiO2 = (0.1~4.0):1, H2O / SiO2 = (1.0~40.0):1.

[0014] Further, in step S1, the seed crystal is prepared using the following method: in step S11, a silicon source and water are mixed to obtain a silicon-containing material; an aluminum source and water are mixed to obtain an aluminum-containing material; in step S12, the aluminum-containing material is added dropwise to the silicon-containing material and stirred to obtain a mixture gel; the pH value of the mixture gel is adjusted to 8.5-12.5, and then a two-stage hydrothermal crystallization treatment is performed to obtain the seed crystal.

[0015] Further, in step S11, the silicon source includes one or more of silica sol, tetraethyl orthosilicate, coarse-porous silica gel, silica powder, fly ash, and silica; the aluminum source includes one or more of sodium aluminate, boehmite, aluminum sulfate, and aluminum nitrate; and / or in step S12, the stirring temperature is 20–100°C, and the time is 0.1–24 h; and / or two-stage hydrothermal crystallization is carried out in a hydrothermal reactor, including a first-stage hydrothermal crystallization and a second-stage hydrothermal crystallization performed sequentially, wherein the temperature of the second-stage hydrothermal crystallization is higher than that of the first-stage hydrothermal crystallization, and the temperature difference is 50–60°C; preferably, the temperature of the first-stage hydrothermal crystallization is 20–60°C, and the time is 4–24 h; the temperature of the second-stage hydrothermal crystallization is 80–120°C, and the time is 6–48 h.

[0016] According to another aspect of the present invention, a cracking catalyst is provided, which is prepared by the preparation method described above.

[0017] According to another aspect of the present invention, the application of the above-described cracking catalyst of the present invention in cracking reactions in the fields of petrochemicals, coal chemicals, and waste plastics treatment is provided.

[0018] By applying the technical solution of this invention, 13X molecular sieves are prepared using waste catalyst resources. These sieves have controllable micro-mesopore specific surface area and large pore volume, high hydrothermal stability, a wide range of silicon-aluminum ratios, and controllable morphology. Then, a novel high-efficiency cracking catalyst is prepared through two-step calcination. This not only reduces the generation of industrial waste, but also helps to reduce the production cost of the catalyst while ensuring the catalytic cracking effect, thereby improving the green sustainability of the cracking process. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0020] As described in the background section of this invention, existing cracking catalysts suffer from high cost and environmental unfriendliness. To address these issues, in a typical embodiment of this invention, a method for preparing cracking catalysts from spent catalysts is provided, comprising the following steps: Step S1, the spent catalyst is subjected to aluminum and silicon dissolution treatments to obtain a silicon-rich liquid and an aluminum-rich liquid; the silicon-rich liquid and the aluminum-rich liquid are mixed to obtain a gel-like mother liquor; seed crystals are added to the gel-like mother liquor, followed by aging and crystallization treatments, and then dried to obtain 13X molecular sieve; Step S2, the 13X molecular sieve is mixed with a platinum precursor solution, stirred for 12–36 hours, then filtered, and the filter cake is... The catalyst precursor is dried at 0–130℃ for 8–16 hours to obtain a catalyst precursor; in step S3, the catalyst precursor is pre-calcined in an inert gas atmosphere to obtain a pre-calcined product; in step S4, the pre-calcined product is calcined in an air atmosphere to obtain a cracking catalyst; wherein, the waste catalyst includes one or more of waste Z-5 molecular sieve catalyst, waste MTO catalyst, waste molecular sieve adsorbent, fly ash, waste FCC catalyst and waste VOC adsorbent; wherein, the calcination temperature is higher than the pre-calcination temperature, and the temperature difference is 250–350℃.

[0021] This invention first involves treating one or more waste catalysts, including waste Z-5 molecular sieve catalyst, waste MTO catalyst, waste molecular sieve adsorbent, fly ash, waste FCC catalyst, and waste VOC adsorbent, with aluminum and silicon dissolution treatments to recover the active components aluminum and silicon, yielding silicon-rich liquid and aluminum-rich liquid. These are mixed to obtain a gel-like mother liquor. Seed crystals are added, and the liquor undergoes aging and crystallization treatments sequentially to shape its structure. After drying, 13X molecular sieve is obtained, which has a controllable micro-mesopore specific surface area and a large pore volume, and a high water content. The catalyst exhibits excellent thermal stability, a wide silicon-to-aluminum ratio range, and controllable morphology. The 13X molecular sieve is then mixed with a platinum precursor solution and stirred for 12–36 hours to initially load platinum. After filtration, the filter cake is dried at 90–130°C for 8–16 hours to obtain the catalyst precursor. Finally, the catalyst precursor is pre-calcined in an inert gas atmosphere, followed by calcination in air at a high temperature of 250–350°C. This high-temperature oxidative calcination transforms the platinum precursor into highly dispersed platinum oxide or platinum metal, yielding the cracking catalyst. Conventional inert gases such as nitrogen and argon are suitable. The platinum precursor includes hexachloroplatinic acid dihydrate.

[0022] This invention utilizes waste catalyst resources to prepare novel high-efficiency cracking catalysts through regeneration or modification, which not only reduces the generation of industrial waste, but also helps to reduce the production cost of catalysts and improve the green sustainability of the cracking process.

[0023] In a preferred embodiment, in step S2, the mass ratio of 13X molecular sieve to platinum precursor is 100:(0.8-1.2), which enables the material containing catalytic metal platinum to be more fully loaded in the molecular sieve.

[0024] To further improve the effect of low-temperature inert calcination, in a preferred embodiment, in step S3, the pre-calcination temperature is 450-550°C and the time is 1-3 hours.

[0025] Accordingly, in order to more fully convert the platinum precursor into highly dispersed active platinum, in a preferred embodiment, the calcination temperature in step S4 is 700-900°C and the time is 3-5 hours, which can further improve the high-temperature oxidation calcination effect.

[0026] In a preferred embodiment, step S1, aluminum dissolution includes: mixing the spent catalyst with NaCO3, calcining at 550–800°C for 60–120 min, then dissolving the calcined product with a monobasic acid, filtering, and obtaining an aluminum-rich liquid and aluminum-dissolved filter residue; preferably, the mass ratio of spent catalyst to NaCO3 is 1:(0.5–1:5); and / or the mass concentration of the monobasic acid is 10–35%; silicon dissolution includes: mixing the aluminum-dissolved filter residue with NaOH and H2O, filtering, and obtaining a silicon-rich liquid; preferably, the mass ratio of aluminum-dissolved filter residue to NaOH and H2O is (2–100):(40–60):(50–400). Under the above conditions, the active components aluminum and silicon in the spent catalyst can be more fully recovered and utilized, reducing the production cost of the catalyst and improving the green sustainability of the cracking process. The monobasic acid is defined using conventional methods in the art, such as hydrochloric acid and nitric acid.

[0027] To improve the preparation effect of 13X molecular sieve, in a preferred embodiment, in step S1, the molar ratio of each component in the gel mother liquor is: SiO2 / Al2O3 = (0.5~6.0):1, Na2O / SiO2 = (0.5~6.0):1, H2O / SiO2 = (10~100):1; preferably, the amount of seed crystals added accounts for 5~20 wt% of the gel mother liquor by weight percentage.

[0028] For similar reasons, in a preferred embodiment, in step S1, aging is carried out under stirring conditions at a temperature of 20–100°C for a time of 0.1–24 h; and / or crystallization is carried out at a temperature of 60–105°C for a time of 0.1–36 h.

[0029] As described above, the 13X molecular sieve prepared by this invention has a controllable micro-to-mesopore specific surface area and a large pore volume, high hydrothermal stability, a wide range of silica-to-alumina ratios, and controllable morphology. In a preferred embodiment, the silica-to-alumina ratio of the 13X molecular sieve is 2.2–2.9, and the pore volume is 0.3–0.5 cm³. 3 / g, specific surface area of ​​700-950m² 2 / g can provide more adsorption sites, introduce mesoporous channels, increase the pore volume inside the molecular sieve crystal, improve the flow and diffusion performance of guest molecules inside the molecular sieve, have high silicon source utilization and good selectivity, and can be controlled according to different adsorbed molecules, thereby significantly reducing the carbon deposition rate of the molecular sieve and facilitating the preparation of subsequent cracking catalysts.

[0030] To further promote the successful formation of the 13X molecular sieve structure, in a preferred embodiment, the molar ratio of each component in the seed crystal is: SiO2 / Al2O3 = (0.1~2.5):1, Na2O / SiO2 = (0.1~4.0):1, H2O / SiO2 = (1.0~40.0):1.

[0031] In a preferred embodiment, in step S1, the seed crystal is prepared using the following method: Step S11, a silicon source and water are mixed to obtain a silicon-containing material; an aluminum source and water are mixed to obtain an aluminum-containing material; Step S12, the aluminum-containing material is added dropwise to the silicon-containing material and stirred to obtain a mixture gel; the pH value of the mixture gel is adjusted to 8.5-12.5, and then a two-stage hydrothermal crystallization treatment is performed to obtain the seed crystal, which is more suitable for the preparation process of the 13X molecular sieve of the present invention.

[0032] To further improve the diffusion performance of 13X molecular sieve, in a preferred embodiment, in step S11, the silicon source includes one or more of silica sol, tetraethyl orthosilicate, coarse-porous silica gel, silica powder, fly ash, and silica; the aluminum source includes one or more of sodium aluminate, boehmite, aluminum sulfate, and aluminum nitrate; and / or the mixing process of the silicon source and water is generally stirred at 20–60°C for 0.1–12 h, with the stirring speed maintained at 200–800 rpm; the mixing process of the aluminum source and water is generally stirred at 20–60°C for 0.1–12 h, with the stirring speed preferably maintained at 200–800 rpm, the mass concentration of the silicon-containing material is 28–99 wt%, and the mass concentration of the aluminum-containing material is 15–99% wt%. and / or in step S12, the stirring temperature is 20–100°C, and the time is 0.1–24 h.

[0033] The hydrothermal crystallization process is carried out in a hydrothermal reactor in two stages, including a first stage and a second stage of hydrothermal crystallization performed sequentially. The temperature of the second stage is higher than that of the first stage, with a temperature difference of 50–60°C. Preferably, the temperature of the first stage is 20–60°C, and the time is 4–24 hours; the temperature of the second stage is 80–120°C, and the time is 6–48 hours. More preferably, the temperature of the first stage is 35–45°C, and the time is 11–13 hours; the temperature of the second stage is 90–100°C, and the time is 22–26 hours.

[0034] By precisely controlling pH, crystallization temperature, and raw material ratio, the uniform arrangement of pores, specific surface area, and pore capacity can be more accurately controlled, making it easier to prepare molecular sieves with superior performance.

[0035] In another typical embodiment of the present invention, a cracking catalyst is also provided, which is prepared by the preparation method described above, and has significantly reduced production costs and can improve the green sustainability of the cracking process.

[0036] In another typical embodiment of the present invention, the application of the above-described cracking catalyst of the present invention in cracking reactions in the fields of petrochemicals, coal chemicals, and waste plastics treatment is also provided.

[0037] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0038] Example 1

[0039] Seed crystal preparation: 21.0 g of silica sol (30% by mass) was dissolved in 36.0 g of deionized water and pretreated in a sealed reactor at 25°C and 500 rpm for 1 hour to obtain a silicon source dispersed phase aqueous solution; 24 g of aluminum sulfate was dissolved in 18.0 g of deionized water and stirred at 25°C and 500 rpm for 1 hour to obtain an aluminum source dispersed phase aqueous solution; the aluminum source aqueous solution was slowly added dropwise to the silicon source aqueous solution and stirred at 60°C for 8 hours to obtain a gel solution; 6.74 g of sodium hydroxide was dissolved in 36 g of deionized water dispersion and added to the gel solution, controlling the pH value to be maintained at 12.2, and the resulting gel solution was placed in a hydrothermal reactor for two-stage temperature-controlled crystallization: the first stage crystallization temperature was 40°C and the time was 12 hours, and the second stage crystallization temperature was 95°C and the time was 24 hours. Deionized water was added as needed during the crystallization process to obtain a seed crystal solution.

[0040] Step S1: The waste Z-5 molecular sieve catalyst is mixed with NaCO3 at a mass ratio of 1:1 and calcined at 700℃ for 90 min. Then, the calcined product is dissolved with a monobasic acid with a mass concentration of 20%, filtered, and aluminum-rich liquid and aluminum-dissolving filter residue are obtained. The aluminum-dissolving filter residue is mixed with NaOH and H2O at a mass ratio of 50:50:200, filtered, and silicon-rich liquid is obtained. The silicon-rich liquid and aluminum-rich liquid are mixed to obtain a gel-like mother liquor. Seed crystals accounting for 15 wt% of the gel-like mother liquor are added to the gel-like mother liquor, and then aging and crystallization treatments are carried out sequentially. The aging temperature is 60℃ and the time is 12 h. The crystallization temperature is 80℃ and the time is 18 h. After drying, 13X molecular sieve is obtained.

[0041] Step S2: Take 100g of 13X molecular sieve and dry it at 110℃ for 4 hours to remove adsorbed moisture. After drying, cool to room temperature. Dissolve 1g of hexachloroplatinic acid dihydrate (H2PtCl6·2H2O) in 500mL of deionized water to form a platinum precursor solution. Add the dried 13X molecular sieve to the prepared platinum precursor solution and stir thoroughly with a magnetic stirrer for 24 hours. Then filter, place the filtered molecular sieve in a drying oven, and further dry it at 110℃ for 12 hours to obtain the catalyst precursor.

[0042] Step S3: The catalyst precursor is placed in a molybdenum cloth furnace and pre-calcined in an inert gas atmosphere at a temperature of 500°C for 2 hours to obtain the pre-calcined product.

[0043] Step S4: The pre-calcined product is calcined in air at a temperature of 800°C for 4 hours to obtain the cracking catalyst.

[0044] Example 2

[0045] The difference from Example 1 is that,

[0046] Seed crystal preparation: 1g of silicon powder was dissolved in 18g of deionized water and pretreated in a sealed reactor at 25℃ and 500rpm for 1 hour to obtain a silicon source dispersed phase aqueous solution. 12g of aluminum nitrate was dissolved in 18.0g of deionized water and stirred at 35℃ and 500rpm for 1 hour to prepare an aluminum source dispersed phase aqueous solution. The prepared aluminum source aqueous solution was slowly added dropwise to the silicon source aqueous solution, and stirring was continued at 50℃ for 6 hours to obtain a gel solution. 2g of sodium hydroxide was dissolved in 36g of deionized water to prepare a dispersion, which was slowly added to the gel solution, controlling the pH value at 11.8. The mixed gel solution was then transferred to a hydrothermal reactor for a two-stage temperature-controlled crystallization process: the first stage crystallization temperature was set at 50℃ for 14 hours; the second stage crystallization temperature was controlled at 100℃ for 18 hours. Deionized water was added as needed during the crystallization process to obtain a seed crystal solution.

[0047] Example 3

[0048] The difference from Example 1 is that,

[0049] Seed crystal preparation: 0.17g of silicon powder was dissolved in 6g of deionized water and pretreated in a sealed reactor at 25℃ and 200rpm for 1 hour to obtain an aqueous solution of silicon source dispersion. 12g of aluminum nitrate was dissolved in 18.0g of deionized water and stirred at 35℃ and 200rpm for 1 hour to prepare an aqueous solution of aluminum source dispersion. The aluminum source solution was slowly added to the silicon source solution and stirred at 100℃ for 24 hours to obtain a gel solution. 0.9g of sodium hydroxide was dissolved in 6g of deionized water to prepare a dispersion, which was then slowly added to gel solution E, adjusting the pH to 12.5. The prepared gel was then poured into a hydrothermal reactor for two-stage crystallization: first, crystallization was carried out at 60℃ for 24 hours, and then the temperature was increased to 120℃ for 48 hours. Deionized water was added as needed during the crystallization process to obtain a seed crystal solution.

[0050] Step S1: The waste FCC catalyst is mixed with NaCO3 at a mass ratio of 1:0.5 and calcined at 550℃ for 120 min. Then, the calcined product is dissolved with a 10% monobasic acid and filtered to obtain an aluminum-rich liquid and an aluminum-dissolving filter residue. The aluminum-dissolving filter residue is mixed with NaOH and H2O at a mass ratio of 2:40:50 and filtered to obtain a silicon-rich liquid. The silicon-rich liquid and the aluminum-rich liquid are mixed to obtain a gel-like mother liquor. Seed crystals accounting for 5 wt% of the gel-like mother liquor are added to the gel-like mother liquor, and then aging and crystallization treatments are carried out sequentially. The aging temperature is 20℃ and the time is 24 h. The crystallization temperature is 60℃ and the time is 36 h. After drying, 13X molecular sieve is obtained.

[0051] Step S2: Take 100 g of 13X molecular sieve and dry it at 110 °C for 4 hours to remove adsorbed moisture. After drying, cool to room temperature. Dissolve 1 g of hexachloroplatinic acid dihydrate (H₂PtCl₆·2H₂O) in 500 mL of deionized water to form a platinum precursor solution. Add the dried 13X molecular sieve to the prepared platinum precursor solution and stir thoroughly with a magnetic stirrer for 12 hours. Then filter, place the filtered molecular sieve in a drying oven, and further dry it at 90 °C for 16 hours to obtain the catalyst precursor.

[0052] Example 4

[0053] The difference from Example 1 is that,

[0054] Seed crystal preparation: 14.65g of tetraethyl orthosilicate was mixed with 36g of deionized water and pretreated in a sealed reactor at 25℃ and 800rpm for 1 hour to obtain a silicon source dispersed phase aqueous solution. 12g of aluminum nitrate was dissolved in 18.0g of deionized water and stirred at 35℃ and 800rpm for 1 hour to obtain an aluminum source dispersed phase aqueous solution. The aluminum source solution was gradually added dropwise to the silicon source solution and mixed and stirred at 20℃ for 0.1 hours to prepare a gel solution. 0.56g of sodium hydroxide was dissolved in 6g of deionized water as a dispersion and slowly poured into the gel solution, maintaining a pH of 8.5. The prepared gel was introduced into a hydrothermal reactor to perform a segmented crystallization reaction: first, the crystallization temperature was set at 20℃ and maintained for 4 hours; then, it was increased to 80℃ and maintained for 6 hours. Deionized water was added as needed during the crystallization process to obtain a seed crystal solution.

[0055] Step S1: The waste molecular sieve adsorbent is mixed with NaCO3 at a mass ratio of 1:1.5 and calcined at 800℃ for 60 min. Then, the calcined product is dissolved with a monobasic acid with a mass concentration of 35%, filtered, and aluminum-rich liquid and aluminum-dissolving filter residue are obtained. The aluminum-dissolving filter residue is mixed with NaOH and H2O at a mass ratio of 100:60:400 and filtered to obtain silicon-rich liquid. The silicon-rich liquid and aluminum-rich liquid are mixed to obtain a gel-like mother liquor. Seed crystals accounting for 20 wt% of the gel-like mother liquor are added to the gel-like mother liquor, and then aging and crystallization treatments are carried out sequentially. The aging temperature is 100℃ and the time is 0.1 h. The crystallization temperature is 105℃ and the time is 0.1 h. After drying, 13X molecular sieve is obtained.

[0056] Step S2: Take 100 g of 13X molecular sieve and dry it at 110 °C for 4 hours to remove adsorbed moisture. After drying, cool to room temperature. Dissolve 1 g of hexachloroplatinic acid dihydrate (H₂PtCl₆·2H₂O) in 500 mL of deionized water to form a platinum precursor solution. Add the dried 13X molecular sieve to the prepared platinum precursor solution and stir thoroughly with a magnetic stirrer for 36 hours. Then filter, place the filtered molecular sieve in a drying oven, and further dry it at 130 °C for 8 hours to obtain the catalyst precursor.

[0057] Example 5

[0058] Seed crystal preparation: 21.0 g of silica sol (30% by mass) was dissolved in 36.0 g of deionized water and pretreated in a sealed reactor at 25°C and 500 rpm for 1 hour to obtain a silicon source dispersed phase aqueous solution; 24 g of aluminum sulfate was dissolved in 18.0 g of deionized water and stirred at 25°C and 500 rpm for 1 hour to obtain an aluminum source dispersed phase aqueous solution; the aluminum source aqueous solution was slowly added dropwise to the silicon source aqueous solution and stirred at 60°C for 8 hours to obtain a gel solution; 6.74 g of sodium hydroxide was dissolved in 36 g of deionized water dispersion and added to the gel solution, controlling the pH value to be maintained at 12.2, and the resulting gel solution was placed in a hydrothermal reactor for two-stage temperature-controlled crystallization: the first stage crystallization temperature was 40°C and the time was 12 hours, and the second stage crystallization temperature was 95°C and the time was 24 hours. Deionized water was added as needed during the crystallization process to obtain a seed crystal solution.

[0059] Step S1: The waste Z-5 molecular sieve catalyst is mixed with NaCO3 at a mass ratio of 1:1 and calcined at 700℃ for 90 min. Then, the calcined product is dissolved with a monobasic acid with a mass concentration of 20%, filtered, and aluminum-rich liquid and aluminum-dissolving filter residue are obtained. The aluminum-dissolving filter residue is mixed with NaOH and H2O at a mass ratio of 50:50:200, filtered, and silicon-rich liquid is obtained. The silicon-rich liquid and aluminum-rich liquid are mixed to obtain a gel-like mother liquor. Seed crystals accounting for 15 wt% of the gel-like mother liquor are added to the gel-like mother liquor, and then aging and crystallization treatments are carried out sequentially. The aging temperature is 60℃ and the time is 12 h. The crystallization temperature is 80℃ and the time is 18 h. After drying, 13X molecular sieve is obtained.

[0060] Step S2: Take 100g of 13X molecular sieve and dry it at 110℃ for 4 hours to remove adsorbed moisture. After drying, cool to room temperature. Dissolve 1g of hexachloroplatinic acid dihydrate (H2PtCl6·2H2O) in 500mL of deionized water to form a platinum precursor solution. Add the dried 13X molecular sieve to the prepared platinum precursor solution and stir thoroughly with a magnetic stirrer for 24 hours. Then filter, place the filtered molecular sieve in a drying oven, and further dry it at 110℃ for 12 hours to obtain the catalyst precursor.

[0061] Step S3: The catalyst precursor is placed in a molybdenum cloth furnace and pre-calcined in an inert gas atmosphere at a temperature of 450°C for 3 hours to obtain the pre-calcined product.

[0062] Step S4: The pre-calcined product is calcined in air at a temperature of 700°C for 5 hours to obtain the cracking catalyst.

[0063] Example 6

[0064] Seed crystal preparation: 21.0 g of silica sol (30% by mass) was dissolved in 36.0 g of deionized water and pretreated in a sealed reactor at 25°C and 500 rpm for 1 hour to obtain a silicon source dispersed phase aqueous solution; 24 g of aluminum sulfate was dissolved in 18.0 g of deionized water and stirred at 25°C and 500 rpm for 1 hour to obtain an aluminum source dispersed phase aqueous solution; the aluminum source aqueous solution was slowly added dropwise to the silicon source aqueous solution and stirred at 60°C for 8 hours to obtain a gel solution; 6.74 g of sodium hydroxide was dissolved in 36 g of deionized water dispersion and added to the gel solution, controlling the pH value to be maintained at 12.2, and the resulting gel solution was placed in a hydrothermal reactor for two-stage temperature-controlled crystallization: the first stage crystallization temperature was 40°C and the time was 12 hours, and the second stage crystallization temperature was 95°C and the time was 24 hours. Deionized water was added as needed during the crystallization process to obtain a seed crystal solution.

[0065] Step S1: The waste Z-5 molecular sieve catalyst is mixed with NaCO3 at a mass ratio of 1:1 and calcined at 700℃ for 90 min. Then, the calcined product is dissolved with a monobasic acid with a mass concentration of 20%, filtered, and aluminum-rich liquid and aluminum-dissolving filter residue are obtained. The aluminum-dissolving filter residue is mixed with NaOH and H2O at a mass ratio of 50:50:200, filtered, and silicon-rich liquid is obtained. The silicon-rich liquid and aluminum-rich liquid are mixed to obtain a gel-like mother liquor. Seed crystals accounting for 15 wt% of the gel-like mother liquor are added to the gel-like mother liquor, and then aging and crystallization treatments are carried out sequentially. The aging temperature is 60℃ and the time is 12 h. The crystallization temperature is 80℃ and the time is 18 h. After drying, 13X molecular sieve is obtained.

[0066] Step S2: Take 100g of 13X molecular sieve and dry it at 110℃ for 4 hours to remove adsorbed moisture. After drying, cool to room temperature. Dissolve 1g of hexachloroplatinic acid dihydrate (H2PtCl6·2H2O) in 500mL of deionized water to form a platinum precursor solution. Add the dried 13X molecular sieve to the prepared platinum precursor solution and stir thoroughly with a magnetic stirrer for 24 hours. Then filter, place the filtered molecular sieve in a drying oven, and further dry it at 110℃ for 12 hours to obtain the catalyst precursor.

[0067] Step S3: The catalyst precursor is placed in a molybdenum cloth furnace and pre-calcined in an inert gas atmosphere at a temperature of 550°C for 1 hour to obtain the pre-calcined product.

[0068] Step S4: The pre-calcined product is calcined in air at a temperature of 900°C for 3 hours to obtain the cracking catalyst.

[0069] Comparative Example 1

[0070] The difference from Example 1 is that no pre-calcination was performed.

[0071] Comparative Example 2

[0072] The difference from Example 1 is that,

[0073] Step S3: The catalyst precursor is placed in a molybdenum cloth furnace and pre-calcined in an inert gas atmosphere at a temperature of 350°C for 3 hours to obtain the pre-calcined product.

[0074] Step S4: The pre-calcined product is calcined in air at a temperature of 950°C for 5 hours to obtain the cracking catalyst.

[0075] Comparative Example 3

[0076] The difference from Example 1 is that,

[0077] Step S3: The catalyst precursor is placed in a molybdenum cloth furnace and pre-calcined in an inert gas atmosphere at a temperature of 650°C for 1 hour to obtain the pre-calcined product.

[0078] Step S4: The pre-calcined product is calcined in air at a temperature of 600°C for 3 hours to obtain the cracking catalyst.

[0079] The molar ratios of each component in the seed crystals and gel-like mother liquor, as well as the performance test results of the 13X molecular sieve and cracking catalyst in the above embodiments and comparative examples, are shown in Tables 1 and 2.

[0080] Test method:

[0081] Molar ratio, silicon-to-aluminum ratio: X-ray fluorescence spectroscopy (XRF);

[0082] Pore ​​volume and specific surface area: BET test method.

[0083] Catalytic rate, selectivity, and total yield of trienes: The cracking catalyst was used in the reaction of naphtha steam cracking to prepare trienes (trienes are ethylene, propylene, and butadiene). The specific reaction conditions were: reaction temperature of 550℃, reaction pressure of 80KPa, reaction time of 2 hours, and water-oil mass ratio of 0.6.

[0084] Table 1

[0085]

[0086]

[0087] Table 2

[0088]

[0089] As can be seen from the above, compared with the comparative examples, the embodiments of the present invention utilize waste catalyst resources to prepare 13X molecular sieves, which have controllable micro- and mesopore specific surface areas and large pore volumes, high hydrothermal stability, a wide range of silicon-to-aluminum ratios, and controllable morphology. Then, a novel high-efficiency cracking catalyst is prepared through a two-step calcination process, which not only reduces the generation of industrial waste but also helps to lower the production cost of the catalyst and improve the green sustainability of the cracking process. Furthermore, it can be seen that when all process parameters are within the preferred range of the present invention, the overall performance of the prepared catalyst is superior.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for the preparation of a cracking catalyst from spent catalyst, characterized in that, The method comprises the following steps: Step S1, mixing the waste catalyst with NaCO3, calcining at 550-800℃ for 60-120min, then dissolving the calcined product with monobasic acid, filtering to obtain an aluminum-rich liquid and an aluminum-dissolved residue; mixing the aluminum-dissolved residue with NaOH and H2O, filtering to obtain a silicon-rich liquid, mixing the silicon-rich liquid with the aluminum-rich liquid to obtain a gel-like mother liquor; adding seed crystals to the gel-like mother liquor, then sequentially performing aging treatment and crystallization treatment, and drying to obtain 13X molecular sieve; the seed crystals are prepared by the following method: Step S11, mixing a silicon source and water to obtain a silicon-containing material; mixing an aluminum source and water to obtain an aluminum-containing material; Step S12, adding the aluminum-containing material dropwise into the silicon-containing material, stirring to obtain a mixture gel; adjusting the pH value of the mixture gel to 8.5-12.5, then performing two-stage hydrothermal crystallization treatment to obtain the seed crystals; the two-stage hydrothermal crystallization is performed in a hydrothermal reactor, comprising sequentially performing first-stage hydrothermal crystallization and second-stage hydrothermal crystallization, the temperature of the second-stage hydrothermal crystallization is higher than that of the first-stage hydrothermal crystallization, and the temperature difference is 50-60℃; Step S2, mixing the 13X molecular sieve with a platinum precursor solution, stirring for 12-36 hours, then filtering, and drying the filter cake at 90-130℃ for 8-16 hours to obtain a catalyst precursor; Step S3, pre-calcining the catalyst precursor in an inert gas atmosphere to obtain a pre-calcined product; Step S4, calcining the pre-calcined product in an air atmosphere to obtain the cracking catalyst; The waste catalyst comprises one or more of waste MTO catalyst, waste molecular sieve adsorbent, waste FCC catalyst and waste VOC adsorbent. The temperature of the calcining is higher than the temperature of the pre-calcining, and the temperature difference is 250-350℃.

2. The method for preparing a cracking catalyst from a waste catalyst according to claim 1, characterized in that, in the step S3, the temperature of the pre-calcining is 450-550℃, and the time is 1-3 hours; and / or in the step S4, the temperature of the calcining is 700-900℃, and the time is 3-5 hours.

3. The method of preparing a cracking catalyst from spent catalyst according to claim 1 or 2, characterized in that, in the step S1, the mass concentration of the monobasic acid is 10-35%; the mass ratio of the aluminum-dissolved residue, NaOH and H2O is (2-100):(40-60):(50-400).

4. The method of preparing a cracking catalyst from spent catalyst according to claim 1 or 2, characterized in that, in the step S1, the molar ratio of the components in the gel-like mother liquor is: SiO2 / Al2O3=(0.5-6.0):1, Na2O / SiO2=(0.5-6.0):1, and H2O / SiO2=(10-100):

1.

5. The method of preparing a cracking catalyst from spent catalyst according to claim 4, characterized in that, The amount of the seed crystals added accounts for 5-20wt% of the gel-like mother liquor.

6. The method of preparing a cracking catalyst from spent catalyst according to claim 1 or 2, characterized by, in the step S1, the aging treatment is performed under stirring, the temperature is 20-100℃, and the time is 0.1-24h; and / or the temperature of the crystallization treatment after the aging treatment is 60-105℃, and the time is 0.1-36h.

7. The method for preparing a cracking catalyst from a spent catalyst according to claim 1 or 2, characterized in that, The 13X molecular sieve has a silicon-aluminum ratio of 2.2-2.9, a pore volume of 0.3-0.5 cm 3 / g, and a specific surface area of 700-950 m 2 / g; and / or the molar ratio of each component in the seed crystal is: SiO2 / Al2O3 = (0.1-2.5):1, Na2O / SiO2 = (0.1-4.0):1, H2O / SiO2 = (1.0-40.0):

1.

8. The method for preparing a cracking catalyst from a spent catalyst according to claim 7, characterized in that, in the step S11, the silicon source includes one or more of silica sol, tetraethyl orthosilicate, coarse-pore silica gel, silicon powder, fly ash and white carbon black; the aluminum source includes one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate and aluminum nitrate; and / or in the step S12, the temperature for stirring is 20-100°C, and the time is 0.1-24h; and / or the temperature for the first-stage hydrothermal crystallization is 20-60°C, and the time is 4-24h; the temperature for the second-stage hydrothermal crystallization is 80-120°C, and the time is 6-48h.

9. A cracking catalyst characterized by, The cracking catalyst is prepared by the method according to any one of claims 1-8.

10. Use of the cracking catalyst according to claim 9 in a cracking reaction in the field of petroleum chemical industry, coal chemical industry or waste plastic treatment.

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