13x molecular sieve and method for making same

Abstract

The application provides a 13X type molecular sieve and a preparation method thereof. The method comprises the following steps: S1, a gel system containing a silicon source and an aluminum source is sequentially subjected to first crystallization treatment and second crystallization treatment to obtain a crystallization product-containing system; the temperature of the first crystallization treatment is 20-60 DEG C, and the time is 4-24 h; the temperature of the second crystallization treatment is at least 20 DEG C higher than that of the first crystallization treatment, and the time is 6-48 h; S2, a mixed system of inorganic waste and a flux is subjected to calcination to obtain a calcination product; the calcination product is reacted with an aqueous acid solution, and after first solid-liquid separation, a residue and a first filtrate are obtained; the residue is reacted with an aqueous alkali solution, and after second solid-liquid separation, a second filtrate is obtained; the first filtrate and the second filtrate are mixed to obtain a mother liquor; wherein the inorganic waste contains aluminum elements, silicon elements and oxygen elements; S3, the crystallization product in the crystallization product-containing system is mixed with the mother liquor, and after aging and third crystallization treatment, a 13X type molecular sieve is obtained.

Description

Technical Field

[0001] This invention relates to the field of inorganic material preparation technology, and more specifically, to a 13X type molecular sieve and its preparation method. Background Technology

[0002] Molecular sieves are aluminosilicates characterized by uniform pore size, regular crystal structure, abundant pore system, large specific surface area, and good thermal stability. They are considered preferred adsorbent materials for removing oxygen-containing compounds from olefins. FAU-type (X and Y-type) molecular sieves have a pore size of approximately 0.74 nm. Among them, X-type molecular sieves are particularly effective at removing oxygen-containing compound impurities from olefins, and have been extensively studied and applied in industrial practice. However, when used for olefin purification, X-type molecular sieves exhibit high heat of adsorption, typically requiring pre-loading; furthermore, some olefins are adsorbed during the purification process.

[0003] Research and development of X-type molecular sieve adsorbents mainly focuses on the following three aspects: first, selective adsorption of oxygen-containing compounds while minimizing the adsorption of olefins; second, effectively reducing the heat of adsorption; and third, effectively increasing the adsorption capacity and purification depth of the adsorbent. Adsorption separation has been widely applied in petroleum cracking and refinery catalytic cracking. Currently, research on adsorption separation processes mainly focuses on the removal of oxides from C4 and higher hydrocarbons. Furthermore, hydrocarbon products generated from the indirect liquefaction of coal via Fischer-Tropsch synthesis have different carbon number distributions, and the oxygen-containing compounds within these products are diverse, with significant differences in molecular weight and structure. Commonly used molecular sieves also vary in pore size and composition. Therefore, there is no single adsorbent suitable for separating oxides from Fischer-Tropsch products with all carbon number distributions. Thus, adsorbents with uniformly ordered micropores, large specific surface area, high adsorption capacity, and low heat of adsorption have broad application prospects in the field of adsorption separation.

[0004] Existing literature (publication number CN103523796A) proposes a method for preparing submicron X-type molecular sieves. The molecular sieve uses silica sol as the silicon source to prepare a crystallization directing agent; a molecular mother liquor is prepared using water glass, sodium aluminate or aluminum hydroxide and sodium hydroxide; after adding the directing agent to the mother liquor, it is aged for a certain period of time, and then a weakly polar water-soluble dispersant is added. After stirring evenly, the submicron X-type molecular sieve is obtained by hydrothermal crystallization in a closed container with microwave assistance.

[0005] However, existing methods for preparing 13X molecular sieves still suffer from problems such as low silicon source utilization, difficulty in controlling product size and morphology, and poor product dispersibility.

[0006] Therefore, it is of great significance to study and develop a method for preparing 13X molecular sieves with high silicon source utilization, easy control of product size and morphology, and good product dispersibility. Summary of the Invention

[0007] The main objective of this invention is to provide a 13X molecular sieve and its preparation method, so as to solve the problems of low silicon source utilization, difficulty in controlling product size and morphology, and poor product dispersibility in the preparation methods of 13X molecular sieves in the prior art.

[0008] To achieve the above objectives, the present invention provides a method for preparing a 13X type molecular sieve, comprising: step S1, subjecting a gel system containing a silicon source and an aluminum source to a first crystallization treatment and a second crystallization treatment sequentially to obtain a system containing crystallized products; wherein the temperature of the first crystallization treatment is 20–60°C and the time is 4–24 h, and the temperature of the second crystallization treatment is at least 20°C higher than the temperature of the first crystallization treatment and the time is 6–48 h; step S2, calcining a mixture of inorganic waste and flux to obtain a calcined product; reacting the calcined product with an acidic aqueous solution, and obtaining a filter residue and a first filtrate after a first solid-liquid separation; reacting the filter residue with an alkaline aqueous solution, and obtaining a second filtrate after a second solid-liquid separation; mixing the first filtrate and the second filtrate to obtain a mother liquor; wherein the inorganic waste includes aluminum, silicon, and oxygen; and step S3, mixing the crystallized product in the system containing crystallized products with the mother liquor, and obtaining a 13X type molecular sieve after sequential aging and a third crystallization treatment.

[0009] Furthermore, the temperature of the second crystallization treatment is 20 to 100°C higher than that of the first crystallization treatment; preferably, the temperature of the second crystallization treatment is 80 to 120°C, and the time is 6 to 48 hours.

[0010] Further, the inorganic waste includes 10.5–38.5 wt% aluminum, 8.4–37.3 wt% silicon, and 43.6–52.1 wt% oxygen, with the balance being other elements; preferably, the inorganic waste is selected from one or more of the group consisting of waste ZSM-5 molecular sieve catalyst, waste MTO catalyst, fly ash, waste FCC catalyst, and waste VOC adsorbent.

[0011] Further, the preparation method of the gel system in step S1 includes: step S11, mixing a silicon source with a first solvent to obtain a silicon source dispersion; preferably, the mass concentration of the silicon source dispersion is 28-99 wt%; step S12, mixing an aluminum source with a second solvent to obtain an aluminum source dispersion; preferably, the mass concentration of the aluminum source dispersion is 15-99 wt%; step S13, mixing the silicon source dispersion and the aluminum source dispersion, stirring, and adjusting the pH to 8.5-12.5 to obtain the gel system; preferably, step S13... The method includes: adding an aluminum source dispersion dropwise to a silicon source dispersion, stirring, and adjusting the pH to 11.9–12.1 to obtain a gel system; preferably, the stirring temperature is 20–100°C and the stirring time is 0.1–24 h; preferably, the silicon source is selected from one or more of the group consisting of silica sol, tetraethyl orthosilicate, coarse-porous silica gel, silica powder, fly ash, and silica; preferably, the aluminum source is selected from one or more of the group consisting of sodium aluminate, boehmite, aluminum sulfate, and aluminum nitrate; preferably, the first solvent and the second solvent are selected from water.

[0012] Furthermore, the crystallization product system includes SiO2 and Al2O3, preferably with a molar ratio of SiO2 to Al2O3 of (0.01–2.5):1; preferably, the crystallization product system also includes Na2O and H2O, preferably with a molar ratio of Na2O to SiO2 of (0.01–4.0):1; and a molar ratio of H2O to SiO2 of (1.0–40.0):1.

[0013] Furthermore, the weight ratio of inorganic waste to flux is 1:(0.5 to 1:5).

[0014] Furthermore, the roasting temperature is 550–800℃, and the time is 60–120 min.

[0015] Furthermore, the mass concentration of the acidic aqueous solution is 10–35%.

[0016] Further, the weight ratio of the alkaline compound in the filter residue and the alkaline aqueous solution to the water in the alkaline aqueous solution is (2-100):(40-60):(50-400); preferably, the flux is sodium carbonate; preferably, the acidic compound in the acidic aqueous solution is a monobasic acid, more preferably, the acidic compound in the acidic aqueous solution is selected from nitric acid and / or hydrochloric acid; preferably, the alkaline compound in the alkaline aqueous solution is selected from NaOH and / or KOH.

[0017] Further, the mother liquor obtained in step S2 includes SiO2 and Al2O3, preferably with a molar ratio of SiO2 to Al2O3 of (0.5-6.0):1; preferably, the mother liquor also includes Na2O and H2O, preferably with a molar ratio of Na2O to SiO2 of (0.5-6.0):1; and a molar ratio of H2O to SiO2 of (10-100):1.

[0018] Furthermore, the weight ratio of the crystallized product to the mother liquor in the crystallized product system is (5-20):100.

[0019] Furthermore, the weight ratio of the first filtrate to the second filtrate is 1:(2.5 to 5.5).

[0020] Furthermore, in step S3, the aging temperature is 20–100°C, and the time is 0.1–24 h.

[0021] Furthermore, the temperature of the third crystallization treatment is 60–150°C, and the time is 0.1–36 h; preferably, the temperature of the third crystallization treatment is 90–120°C, and the time is 18–30 h.

[0022] To achieve the above objectives, another aspect of the present invention provides a 13X-type molecular sieve prepared by the method described in this application, wherein the 13X-type molecular sieve has a silica-to-alumina ratio of 2.2 to 2.9 and a pore volume of 0.35 to 0.5 cm³. 3 / g, specific surface area is 800-950m² 2 / g.

[0023] By applying the technical solution of this invention, compared to the traditional method of obtaining a crystallized product system through a single crystallization process, the two-stage crystallization process applied to the gel system containing silicon and aluminum sources can effectively control the formation and growth of seed crystals. The first-stage crystallization process is carried out under lower temperature and time conditions, which is conducive to the initial formation of seed crystals. The second-stage crystallization process is carried out under higher temperature and time conditions, which is conducive to the further growth and improvement of seed crystals, thereby improving the quality and controllability of seed crystals. Moreover, mixing the mother liquor obtained from the treatment of inorganic waste containing the above-mentioned specific elements with the crystallized product system to prepare 13X type molecular sieves can improve the recycling rate of inorganic waste and increase its utilization value.

[0024] Compared to other ranges, using the specific conditions described above (the temperature and time of the first and second crystallization treatments are within the range of the above application) to perform two-stage crystallization treatment on the gel system is beneficial for more effectively controlling the growth rate and final size of the crystals, improving the crystallinity and purity of the crystallization products, and facilitating the subsequent formation of 13X type molecular sieves with controllable morphology and size and relatively wide silica-alumina ratio. It also helps to improve its dispersibility.

[0025] Compared with 13X molecular sieves prepared by traditional methods, the 13X molecular sieve prepared by the above-mentioned preparation method of this application has better adsorption capacity and has good application prospects in the field of shape-selective adsorption. Detailed Implementation

[0026] 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.

[0027] As described in the background section, existing methods for preparing 13X molecular sieves suffer from low silicon source utilization, difficulty in controlling product size and morphology, and poor product dispersibility. To address the aforementioned technical problems, the first aspect of this application provides a method for preparing a 13X-type molecular sieve. This method includes: Step S1, sequentially subjecting a gel system containing a silicon source and an aluminum source to a first crystallization treatment and a second crystallization treatment to obtain a system containing crystallized products; wherein the temperature of the first crystallization treatment is 20–60°C, and the time is 4–24 h; the temperature of the second crystallization treatment is at least 20°C higher than the temperature of the first crystallization treatment, and the time is 6–48 h; Step S2, calcining a mixture of inorganic waste and flux to obtain a calcined product; reacting the calcined product with an acidic aqueous solution, and obtaining a filter residue and a first filtrate after a first solid-liquid separation; reacting the filter residue with an alkaline aqueous solution, and obtaining a second filtrate after a second solid-liquid separation; mixing the first filtrate and the second filtrate to obtain a mother liquor; wherein the inorganic waste includes aluminum, silicon, and oxygen; Step S3, mixing the crystallized product in the system containing crystallized products with the mother liquor, and sequentially subjecting the mixture to aging and a third crystallization treatment to obtain a 13X-type molecular sieve.

[0028] Compared to traditional methods that involve a single crystallization process to obtain a crystallized product system, the two-stage crystallization process described above for a gel system containing silicon and aluminum sources can effectively control the formation and growth of seed crystals. The first crystallization process, conducted at lower temperatures and times, facilitates the initial formation of seed crystals. The second crystallization process, conducted at higher temperatures and times, promotes further growth and refinement of the seed crystals, thereby improving the quality and controllability of the seed crystals. Furthermore, mixing the mother liquor obtained from the treatment of inorganic waste containing the aforementioned specific elements with the crystallized product system to prepare 13X-type molecular sieves can improve the recycling rate of inorganic waste and enhance its utilization value.

[0029] Compared to other ranges, using the specific conditions described above (the temperature and time of the first and second crystallization treatments are within the range of the above application) to perform two-stage crystallization treatment on the gel system is beneficial for more effectively controlling the growth rate and final size of the crystals, improving the crystallinity and purity of the crystallization products, and facilitating the subsequent formation of 13X type molecular sieves with controllable morphology and size and relatively wide silica-alumina ratio. It also helps to improve its dispersibility.

[0030] Compared with 13X molecular sieves prepared by traditional methods, the 13X molecular sieve prepared by the above-mentioned preparation method of this application has better adsorption capacity and has good application prospects in the field of shape-selective adsorption.

[0031] In a preferred embodiment, the temperature of the second crystallization treatment is 20–100°C higher than that of the first crystallization treatment. Compared to other ranges, limiting the temperature difference between the two crystallization treatments to the above range allows for more flexible adjustment of the silicon-to-aluminum ratio, facilitating the preparation of molecular sieves with different silicon-to-aluminum ratios as needed. This is beneficial for the subsequent formation of 13X-type molecular sieves with controllable morphology and size and a wide silicon-to-aluminum ratio, thereby improving the overall performance of the molecular sieve.

[0032] In a preferred embodiment, the temperature of the second crystallization treatment is 80–120°C, and the time is 6–48 hours. Compared to other ranges, limiting the temperature and time of the second crystallization treatment to the above range is beneficial to further improve the utilization rate of silicon source, to further form 13X type molecular sieves with controllable morphology and size and relatively wide silicon-aluminum ratio, and also to further improve its dispersibility.

[0033] To further improve the recycling rate of inorganic waste, preferably, the inorganic waste includes 10.5–38.5 wt% aluminum, 8.4–37.3 wt% silicon, and 43.6–52.1 wt% oxygen, with the balance being other elements.

[0034] The inorganic waste in this application includes, but is not limited to, one or more of the following groups: spent ZSM-5 molecular sieve catalyst, spent MTO catalyst, fly ash, spent FCC catalyst, and spent VOC adsorbent. Using the above-mentioned types of inorganic waste helps to improve its recyclability.

[0035] In a preferred embodiment, the preparation method of the gel system in step S1 includes: step S11, mixing a silicon source with a first solvent to obtain a silicon source dispersion; preferably, the mass concentration of the silicon source dispersion is 28-99 wt%; step S12, mixing an aluminum source with a second solvent to obtain an aluminum source dispersion; preferably, the mass concentration of the aluminum source dispersion is 15-99 wt%; step S13, mixing the silicon source dispersion and the aluminum source dispersion, stirring, and adjusting the pH to 8.5-12.5 to obtain the gel system. Using the above preparation method to prepare the gel system facilitates the formation of seed crystals after the subsequent two-stage crystallization treatment, which is beneficial for accelerating seed crystal growth and obtaining a system containing crystallized products, thus facilitating the subsequent formation of the molecular sieve with the specific crystal form of this application.

[0036] To improve the uniformity of the gel system and facilitate the subsequent two-stage crystallization process, the stirring temperature is preferably 20–100°C and the stirring time is 0.1–24 h.

[0037] In a preferred embodiment, step S13 includes: adding an aluminum source dispersion dropwise to a silicon source dispersion, stirring, and adjusting the pH to 11.9–12.1 to obtain a gel system. Compared to pouring the aluminum source dispersion into the silicon source dispersion, adding the aluminum source dispersion dropwise to the silicon source dispersion is beneficial for improving the crystallinity and purity of the crystallization product. Simultaneously, adjusting the pH within the aforementioned range helps to accelerate the crystallization rate of the subsequent two-stage crystallization process, shortens the crystallization time, and facilitates the subsequent formation of the molecular sieve with the specific crystal form described in this application.

[0038] In this application, the silicon source and aluminum source can be of types commonly used in the art. In a preferred embodiment, the silicon source includes, but is not limited to, one or more of the group consisting of silica sol, tetraethyl orthosilicate, coarse-porous silica gel, silica powder, fly ash, and silica; the aluminum source includes, but is not limited to, one or more of the group consisting of sodium aluminate, boehmite, aluminum sulfate, and aluminum nitrate.

[0039] In this application, the first solvent and the second solvent can be of types commonly used in the art. In a preferred embodiment, the first solvent and the second solvent include, but are not limited to, water.

[0040] In a preferred embodiment, the crystallization product system comprises SiO2 and Al2O3, preferably with a molar ratio of SiO2 to Al2O3 of (0.01–2.5):1. Compared to other ranges, limiting the molar ratio of SiO2 to Al2O3 in the crystallization product system to the above range is beneficial for the subsequent formation of 13X type molecular sieves with specific crystal forms.

[0041] In a preferred embodiment, the crystallization product system further includes Na₂O and H₂O, preferably with a Na₂O to SiO₂ molar ratio of (0.01–4.0):1 and an H₂O to SiO₂ molar ratio of (1.0–40.0):1. Compared to other ranges, limiting the molar ratios of Na₂O to SiO₂ and H₂O to SiO₂ in the crystallization product system to the above ranges is beneficial for the subsequent formation of 13X type molecular sieves with specific crystal forms.

[0042] In a preferred embodiment, the weight ratio of inorganic waste to flux is 1:(0.5 to 1:5). The weight ratio of inorganic waste to flux includes, but is not limited to, the above range. Limiting it to the above range is beneficial to improving the processability of inorganic waste, thereby facilitating the utilization of Al, Si, and O elements therein, and thus improving its recycling rate.

[0043] In a preferred embodiment, the calcination temperature is 550–800°C, and the time is 60–120 min. The calcination temperature and time include, but are not limited to, the above ranges. Limiting them to the above ranges is beneficial to improving the leaching rates of Al and Si elements, thereby improving the Al content in the first filtrate and the Si content in the second filtrate, and thus better utilizing the role of the mother liquor.

[0044] In a preferred embodiment, the mass concentration of the acidic aqueous solution is 10-35%. Compared to other ranges, limiting the mass concentration of the acidic aqueous solution to the above range is beneficial to increasing the leaching rate of Al, thereby increasing the Al content in the first filtrate and thus better utilizing the role of the mother liquor.

[0045] To further improve the leaching rate of Al, preferably, the acidic compound in the acidic aqueous solution is a monobasic acid, and more preferably, the acidic compound in the acidic aqueous solution includes, but is not limited to, nitric acid and / or hydrochloric acid.

[0046] In a preferred embodiment, the weight ratio of the alkaline compound in the filter residue and the alkaline aqueous solution to the water in the alkaline aqueous solution is (2-100):(40-60):(50-400). Compared to other ranges, limiting the weight ratio of the alkaline compound in the filter residue and the water in the alkaline aqueous solution to the above range is beneficial to improving the leaching rate of Si, thereby improving the utilization rate of the filter residue and the Si content in the second filtrate, and further facilitating the better utilization of the mother liquor.

[0047] To further improve the leaching rate of Si, preferably, the alkaline compound in the alkaline aqueous solution includes, but is not limited to, NaOH and / or KOH.

[0048] To improve the processability of inorganic waste and facilitate its processing and reuse, sodium carbonate is preferably used as the flux.

[0049] In a preferred embodiment, the mother liquor obtained in step S2 comprises SiO2 and Al2O3, preferably with a molar ratio of SiO2 to Al2O3 of (0.5–6.0):1. Compared to other ranges, limiting the molar ratio of SiO2 to Al2O3 in the mother liquor to the above range is beneficial for the subsequent formation of 13X type molecular sieves with specific crystal forms.

[0050] In a preferred embodiment, the mother liquor further includes Na2O and H2O, preferably with a Na2O to SiO2 molar ratio of (0.5–6.0):1 and an H2O to SiO2 molar ratio of (10–100):1. Compared to other ranges, limiting the molar ratios of Na2O to SiO2 and H2O to SiO2 in the mother liquor to the above ranges is beneficial for the subsequent formation of 13X type molecular sieves with specific crystal forms.

[0051] In a preferred embodiment, the weight ratio of the crystallized product to the mother liquor in the crystallization product system is (5-20):100. The weight ratio of the crystallized product to the mother liquor includes, but is not limited to, the above range. Limiting it to the above range is beneficial to improving the utilization rate of silicon source, aluminum source and inorganic waste, facilitating subsequent aging and third crystallization treatment, and promoting the formation of 13X type molecular sieves with specific crystal forms.

[0052] In a preferred embodiment, in step S3, the aging temperature is 20–100°C, and the time is 0.1–24 h. The aging temperature and time include, but are not limited to, the above ranges. Limiting them to the above ranges facilitates the subsequent third crystallization treatment and also helps to increase the adsorption sites of the obtained 13X molecular sieve and increase its internal pore volume.

[0053] In a preferred embodiment, in step S3, the temperature of the third crystallization treatment is 60–150°C, and the time is 0.1–36 h; preferably, the temperature of the third crystallization treatment is 90–120°C, and the time is 18–30 h. The temperature and time of the third crystallization treatment include, but are not limited to, the above ranges. Limiting them to the above ranges is beneficial to improving the crystal purity of the obtained molecular sieve, reducing impurities, and also beneficial to increasing the adsorption sites of the obtained 13X molecular sieve, increasing its internal pore volume, thereby improving its adsorption performance and broadening its application in the field of shape-selective adsorption.

[0054] The second aspect of this application also provides a method for preparing a 13X-type molecular sieve, wherein the 13X-type molecular sieve has a silica-to-alumina ratio of 2.2 to 2.9 and a pore volume of 0.35 to 0.5 cm³. 3 / g, specific surface area is 800-950m² 2 / g. The 13X molecular sieve provided in this application has a high silica-to-alumina ratio, a large pore volume and specific surface area, and also has good adsorption capacity, showing good application prospects in the field of shape-selective adsorption.

[0055] 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.

[0056] Example 1

[0057] A method for preparing a 13X type molecular sieve includes the following steps:

[0058] (1) 21.0 g of silica sol (mass fraction 30%) was dissolved in 36.0 g of deionized water and pretreated in a sealed reactor at 25 °C for 1 h to obtain a silica source dispersion; 24 g of aluminum sulfate was dissolved in 18.0 g of deionized water and stirred at 25 °C for 1 h to obtain an aluminum source dispersion; the aluminum source dispersion was slowly added dropwise to the silica source dispersion, and the addition was completed in 0.8 h; stirring was continued at 60 °C for 8 h to obtain a mixed system; 6.74 g of sodium hydroxide was dissolved in 36 g of deionized water to obtain... Add the NaOH aqueous solution to the mixed system until the pH value is 12 to obtain a gel system; place it in a hydrothermal reactor and carry out two-stage temperature-controlled crystallization. The first stage crystallization temperature is 40℃ and the time is 12h, and the second stage crystallization temperature is 95℃ and the time is 24h to obtain a system containing crystallized products (where the molar ratio of each component is: SiO2 / Al2O3=1.5:1, Na2O / SiO2=1.6:1, H2O / SiO2=32:1);

[0059] (2) Prepare the waste ZSM-5 molecular sieve catalyst with the composition shown in Table 1 as inorganic waste;

[0060] Table 1

[0061] Waste ZSM-5 molecular sieve catalyst 0.050 19.84 79.64 0.31 0.18

[0062] 10g of the above-mentioned 200-mesh waste ZSM-5 molecular sieve catalyst was mixed with 8g of Na2CO3 and calcined at 650℃ for 120min to obtain the calcined product. Then, the calcined product was dissolved and filtered with a 25% nitric acid solution to obtain an aluminum-rich liquid (i.e., the first filtrate) with an Al content of 1.2mol / L and residue. 10g of the above residue was mixed with 6g of NaOH and 40g of water and filtered to obtain a silicon-rich liquid (i.e., the second filtrate) with a Si content of 2mol / L. The silicon-rich liquid and the aluminum-rich liquid were mixed at a weight ratio of 4:1 to obtain the mother liquor. The molar ratio of SiO2 to Al2O3 in the mother liquor was 3.5:1, the molar ratio of Na2O to SiO2 was 2.8:1, and the molar ratio of H2O to SiO2 was 80:1.

[0063] (3) Take 25g of the crystallized product obtained in step (1) and add it to the mother liquor obtained in step (2). Aged at 60°C for 12h, and placed in a hydrothermal reactor for a third crystallization treatment. The temperature of the third crystallization treatment is 98°C and the time is 24h. Filter and wash until the pH is 7, and dry at 90°C to obtain 13X type molecular sieve.

[0064] Example 2

[0065] Step (1) is the same as in Example 1.

[0066] The difference from Example 1 is that the waste 13X adsorbent with the composition shown in Table 2 is used to replace the waste ZSM-5 molecular sieve catalyst as inorganic waste.

[0067] Table 2

[0068] Waste 13X adsorbent 0.020 72.36 18.0 0.024 0.042

[0069] (2) Mix 12g of the above-mentioned 200-mesh waste 13X adsorbent with 10g of Na2CO3 and calcine at 650℃ for 120min to obtain the calcined product; then dissolve and filter the calcined product with a 15% nitric acid solution to obtain an aluminum-rich liquid (i.e., the first filtrate) with an Al element content of 1.5mol / L and residue; take 15g of the above residue and mix it with 6g of NaOH and 40g of water, filter it to obtain a silicon-rich liquid (i.e., the second filtrate) with a Si element content of 0.8mol / L; mix the silicon-rich liquid and the aluminum-rich liquid at a weight ratio of 3.5:1 to obtain the mother liquor; the molar ratio of SiO2 to Al2O3 in the mother liquor is 1.8:1, the molar ratio of Na2O to SiO2 is 4.5:1, and the molar ratio of H2O to SiO2 is 50:1.

[0070] (3) Take 15g of the crystallized product obtained in step (1) and add it to the mother liquor obtained in step (2). Aged at 60°C for 12h, and placed in a hydrothermal reactor for a third crystallization treatment. The temperature of the third crystallization treatment is 95°C and the time is 24h. Filter and wash until the pH is 7, and dry at 90°C to obtain 13X type molecular sieve.

[0071] Example 3

[0072] Step (1) is the same as in Example 1.

[0073] The difference from Example 1 is that a mixture of the waste 13X adsorbent shown in Table 1 and the waste ZSM-5 molecular sieve catalyst shown in Table 2 is used as inorganic waste.

[0074] The above-mentioned 5g of 200-mesh waste ZSM-5 molecular sieve catalyst, 6g of 200-mesh waste 13X adsorbent, and 15g of Na2CO3 were mixed and calcined at 650℃ for 120min to obtain the calcined product. Then, the calcined product was dissolved and filtered with a 15% nitric acid solution to obtain an aluminum-rich liquid (i.e., the first filtrate) with an Al element content of 1.2mol / L and residue. 15g of the above residue was mixed with 8g of NaOH and 45g of water, and filtered to obtain a silicon-rich liquid (i.e., the second filtrate) with a Si element content of 2mol / L. The silicon-rich liquid and the aluminum-rich liquid were mixed at a weight ratio of 5.5:1 to obtain the mother liquor. The molar ratio of SiO2 to Al2O3 in the mother liquor was 0.5:1, the molar ratio of Na2O to SiO2 was 6:1, and the molar ratio of H2O to SiO2 was 10:1.

[0075] (3) Take 20g of the crystallized product obtained in step (1) and add it to the mother liquor obtained in step (2). Aged at 60℃ for 12h, and placed in a hydrothermal reactor for a third crystallization treatment. The temperature of the third crystallization treatment is 105℃ and the time is 20h. Filter and wash until the pH is 7, and dry at 90℃ to obtain 13X type molecular sieve.

[0076] Example 4

[0077] Step (1) is the same as in Example 1.

[0078] The difference from Example 1 is that: in step (2), the weight ratio of silicon-rich liquid to aluminum-rich liquid is 2.5:1; in step (3), 30g of the crystallized product obtained in step (1) is added to the mother liquor obtained in step (2), aged at 70°C for 152h, and placed in a hydrothermal reactor for a third crystallization treatment, wherein the temperature of the third crystallization treatment is 115°C and the time is 16h; after filtration and washing, the pH is 7, and it is dried at 90°C to obtain 13X type molecular sieve.

[0079] Example 5

[0080] The difference from Example 1 is that the temperature of the first crystallization treatment in step (1) is 20°C and the temperature of the second crystallization treatment is 40°C.

[0081] Example 6

[0082] The difference from Example 1 is that the temperature of the first crystallization treatment in step (1) is 60°C and the temperature of the second crystallization treatment is 80°C.

[0083] Example 7

[0084] The difference from Example 1 is that the temperature of the third crystallization treatment in step (3) is 60°C and the time is 36h.

[0085] Example 8

[0086] The difference from Example 1 is that the temperature of the third crystallization treatment in step (3) is 115°C and the time is 0.1h.

[0087] Example 9

[0088] The difference from Example 1 is that the temperature of the third crystallization treatment in step (3) is 150°C.

[0089] Comparative Example 1

[0090] The difference from Example 1 is that step (1) does not use two-stage crystallization treatment, but uses one-stage crystallization treatment to obtain seed solution, wherein the temperature of the first-stage crystallization treatment is 40°C and the time is 12h; the temperature of the crystallization treatment in step (3) is 100°C.

[0091] Comparative Example 2

[0092] The difference from Example 1 is that step (1) is omitted; in step (2), the weight ratio of silicon-rich liquid to aluminum-rich liquid is 9.5:1 to obtain the mother liquor; step (3) includes: aging the mother liquor obtained in step (2) at 70°C for 15 hours, placing it in a hydrothermal reactor for crystallization treatment, wherein the crystallization temperature is 105°C and the crystallization time is 20 hours; after filtration and washing, the pH is 7, and it is dried at 90°C to obtain 13X molecular sieve.

[0093] Comparative Example 3

[0094] The difference from Example 1 is that step (1) is completely different from Example 1, and no two-stage crystallization treatment is performed; and step (2) is completely different from Example 1, and no silicon-rich liquid and aluminum-rich liquid are used to prepare the mother liquor. Specifically, Comparative Example 3 uses the following method to prepare 13X type molecular sieve: 12.5g of boehmite is dissolved in 25.0g of deionized water and stirred at 25°C for 1h to obtain an aluminum source dispersion; 100.0g of water glass (mass fraction of 28%) is dissolved in 18.0g of deionized water to obtain a silicon source dispersion; the silicon source dispersion is added dropwise to the aluminum source dispersion at a rate of 1mL / min and stirred at 45°C for 24h to obtain a mixed system; 20.2g of... NaOH was dissolved in 15g of deionized water and added to the above mixture. The pH value was maintained at 13.0 to obtain the crystallization treatment system. The crystallization treatment system was transferred to a hydrothermal reactor for temperature-controlled crystallization at 100℃ for 18h. The reaction product was filtered and washed until the pH reached 7, and then dried at 90℃ to obtain 13X molecular sieve.

[0095] Comparative Example 4

[0096] The difference from Example 1 is that the temperature of the first crystallization treatment in step (1) is 70°C and the temperature of the second crystallization treatment is 75°C.

[0097] Table 3 lists the silicon-to-aluminum ratio, BET specific surface area, pore volume, average pore size for BJH adsorption, and silicon source conversion rate of the molecular sieves prepared in the above embodiments and comparative examples of this application. It should be noted that micropores in Table 3 refer to pores with a diameter <2 nm, and mesopores refer to pores with a diameter of 2–50 nm.

[0098] Table 3

[0099]

[0100] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: Compared with the traditional method of obtaining a crystallization product system through a single crystallization process, the above two-stage crystallization process on the gel system containing silicon and aluminum sources can effectively control the formation and growth of seed crystals. The first-stage crystallization process is carried out under lower temperature and time conditions, which helps in the initial formation of seed crystals. The second-stage crystallization process is carried out under higher temperature and time conditions, which helps in the further growth and improvement of seed crystals, thereby improving the quality and controllability of seed crystals. Moreover, mixing the mother liquor obtained after treating inorganic waste containing the above-mentioned specific elements with the crystallization product system to prepare 13X type molecular sieves can improve the recycling rate of inorganic waste and increase its utilization value.

[0101] Compared to other ranges, using the specific conditions described above (the temperature and time of the first and second crystallization treatments are within the range of the above application) to perform two-stage crystallization treatment on the gel system is beneficial for more effectively controlling the growth rate and final size of the crystals, improving the crystallinity and purity of the crystallization products, and facilitating the subsequent formation of 13X type molecular sieves with controllable morphology and size and relatively wide silica-alumina ratio. It also helps to improve its dispersibility.

[0102] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0103] 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 method for preparing 13X type molecular sieve, characterized in that, The preparation method includes: Step S1: The gel system containing silicon source and aluminum source is subjected to a first crystallization treatment and a second crystallization treatment in sequence to obtain a crystallized product system; wherein, the temperature of the first crystallization treatment is 20-60℃ and the time is 4-24h, and the temperature of the second crystallization treatment is at least 20℃ higher than the temperature of the first crystallization treatment and the time is 6-48h. Step S2: The mixture of inorganic waste and flux is roasted to obtain a roasted product; the roasted product is reacted with an acidic aqueous solution, and after a first solid-liquid separation, a filter residue and a first filtrate are obtained; the filter residue is reacted with an alkaline aqueous solution, and after a second solid-liquid separation, a second filtrate is obtained; the first filtrate and the second filtrate are mixed to obtain a mother liquor; wherein the inorganic waste includes aluminum, silicon, and oxygen. Step S3: Mix the crystallized product in the crystallized product system with the mother liquor, and then perform aging and third crystallization treatments in sequence to obtain the 13X type molecular sieve; The preparation method of the gel system in step S1 includes: Step S11: The silicon source is mixed with the first solvent to obtain a silicon source dispersion; the mass concentration of the silicon source dispersion is 28-99 wt%. Step S12: The aluminum source is mixed with the second solvent to obtain an aluminum source dispersion; the mass concentration of the aluminum source dispersion is 15-99 wt%. Step S13: Mix the silicon source dispersion with the aluminum source dispersion, stir, and adjust the pH to 8.5-12.5 to obtain the gel system.

2. The method for preparing 13X-type molecular sieve according to claim 1, characterized in that, The temperature of the second crystallization treatment is 20 to 100°C higher than that of the first crystallization treatment.

3. The method for preparing 13X-type molecular sieve according to claim 2, characterized in that, The second crystallization treatment is performed at a temperature of 80–120°C for a time of 6–48 hours.

4. The method for preparing 13X-type molecular sieve according to claim 1, characterized in that, The inorganic waste includes 10.5–38.5 wt% aluminum, 8.4–37.3 wt% silicon, and 43.6–52.1 wt% oxygen, with the balance being other elements.

5. The method for preparing 13X-type molecular sieve according to claim 1, characterized in that, The inorganic waste is selected from one or more of the following groups: waste ZSM-5 molecular sieve catalyst, waste MTO catalyst, fly ash, waste FCC catalyst, and waste VOC adsorbent.

6. The method for preparing the 13X type molecular sieve according to any one of claims 1 to 5, characterized in that, Step S13 includes: adding the aluminum source dispersion dropwise to the silicon source dispersion, stirring, and adjusting the pH to 11.9-12.1 to obtain the gel system.

7. The method for preparing 13X-type molecular sieve according to claim 6, characterized in that, The stirring temperature is 20–100°C, and the stirring time is 0.1–24 h.

8. The method for preparing the 13X type molecular sieve according to any one of claims 1 to 5, characterized in that, The silicon source is selected from one or more of the group consisting of silica sol, tetraethyl orthosilicate, coarse-porous silica gel, silica powder, fly ash, and silica.

9. The method for preparing the 13X type molecular sieve according to any one of claims 1 to 5, characterized in that, The aluminum source is selected from one or more of the group consisting of sodium aluminate, boehmite, aluminum sulfate, and aluminum nitrate.

10. The method for preparing the 13X type molecular sieve according to any one of claims 1 to 5, characterized in that, The first solvent and the second solvent are selected from water.

11. The method for preparing 13X-type molecular sieve according to claim 6, characterized in that, The crystallization product system includes SiO2 and Al2O3, and the molar ratio of SiO2 to Al2O3 is (0.01~2.5):

1.

12. The method for preparing 13X-type molecular sieve according to claim 11, characterized in that, The crystallization product system further includes Na2O and H2O, wherein the molar ratio of Na2O to SiO2 is (0.01–4.0):1; and the molar ratio of H2O to SiO2 is (1.0–40.0):

1.

13. The method for preparing the 13X type molecular sieve according to any one of claims 1 to 5, characterized in that, The weight ratio of the inorganic waste to the flux is 1:(0.5 to 1:5); and / or, The calcination temperature is 550–800℃, and the time is 60–120 min; and / or, The mass concentration of the acidic aqueous solution is 10–35%; and / or, The weight ratio of the filter residue, the alkaline compound in the alkaline aqueous solution, and the water in the alkaline aqueous solution is (2-100):(40-60):(50-400).

14. The method for preparing the 13X type molecular sieve according to any one of claims 1 to 5, characterized in that, The flux is sodium carbonate.

15. The method for preparing the 13X type molecular sieve according to any one of claims 1 to 5, characterized in that, The acidic compound in the aqueous solution is a monobasic acid.

16. The method for preparing 13X-type molecular sieve according to claim 15, characterized in that, The acidic compound in the aqueous solution is selected from nitric acid and / or hydrochloric acid.

17. The method for preparing the 13X type molecular sieve according to any one of claims 1 to 5, characterized in that, The alkaline compound in the alkaline aqueous solution is selected from NaOH and / or KOH.

18. The method for preparing 13X-type molecular sieve according to claim 13, characterized in that, The mother liquor obtained in step S2 includes SiO2 and Al2O3, and the molar ratio of SiO2 to Al2O3 is (0.5~6.0):

1.

19. The method for preparing 13X-type molecular sieve according to claim 18, characterized in that, The mother liquor also includes Na2O and H2O, wherein the molar ratio of Na2O to SiO2 is (0.5-6.0):1; and the molar ratio of H2O to SiO2 is (10-100):

1.

20. The method for preparing 13X-type molecular sieve according to claim 18, characterized in that, The weight ratio of the crystallized product to the mother liquor in the crystallization product-containing system is (5-20):100; and / or, The weight ratio of the first filtrate to the second filtrate is 1:(2.5 to 5.5).

21. The method for preparing the 13X type molecular sieve according to any one of claims 18 to 20, characterized in that, In step S3, the aging temperature is 20–100°C, and the time is 0.1–24 hours; and / or, The third crystallization treatment is performed at a temperature of 60–150°C for a time of 0.1–36 h.

22. The method for preparing 13X-type molecular sieve according to claim 21, characterized in that, The third crystallization treatment is performed at a temperature of 90–120°C for 18–30 hours.

23. A 13X-type molecular sieve prepared by any one of claims 1 to 22, characterized in that, The 13X type molecular sieve has a silica-to-alumina ratio of 2.2–2.9 and a pore volume of 0.35–0.5 cm³. 3 / g, specific surface area is 800-950m² 2 / g.

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