Method for synthesizing Y-type molecular sieve by using fluorine-containing silicon powder and recovering fluorine resource

Abstract

The invention provides a method for synthesizing a Y-type molecular sieve by using fluorine-containing silicon powder and recovering fluorine resources, which comprises the following steps: A) mixing the fluorine-containing silicon powder with a sodium hydroxide solution, and heating for reaction to obtain a clear solution and a precipitate sodium fluoride; the molar ratio of SiO2 to Na2O in the clear solution is 1.9 to 2.4; b) mixing a part of the clarified solution with a high-alkali sodium metaaluminate solution, and activating to obtain an activated directing agent; c) mixing the residual clear solution, the activated guiding agent, the aluminum sulfate solution and the sodium sulfate solution, and stirring to obtain gel; and D) heating and crystallizing the gel to obtain the Y-type molecular sieve. According to the invention, the removal of organic impurities in the fluorine-containing silicon powder, the efficient separation of fluorine and silicon and the synthesis of the Y-type molecular sieve with high purity and few crystal defects are realized by preparing and filtering the low-modulus sodium silicate and removing a small amount of residual fluorine in the sodium silicate.

Description

Technical Field

[0001] This invention belongs to the field of fluorochemical technology, and in particular relates to a method for synthesizing Y-type molecular sieves using fluorinated silicon powder and recovering fluorine resources. Background Technology

[0002] Over 90% of the world's fluorine resources are associated with phosphate rock. Recovering and utilizing the associated fluorine resources from phosphate rock is an effective way to address my country's fluorine shortage. Currently, the domestic recovery of fluorine from phosphate rock first yields fluorosilicic acid, which is then used to produce fluorosilicates, fluorides, anhydrous hydrogen fluoride, and other products. Fluorinated silicon powder is a new type of solid waste generated during the comprehensive utilization of phosphate rock resources. It is produced by the fluorosilicic acid process for producing anhydrous hydrogen fluoride. Taking Wengfu Lantian Fluorochemical Company's 20kt / a anhydrous hydrogen fluoride plant as an example, it produces approximately 30,000 tons (wet basis) of fluorinated silicon powder annually as a byproduct. The main components of fluorinated silicon powder are SiO2 and fluorosilicic acid, with SiO2 at 35wt%, F at 7wt%, and H2O at 56wt%. The sample mainly contains SiO2, followed by F, with other elements such as Fe, Ca, Na, and K present in smaller quantities. The fluorine in fluorinated silicon powder includes both free fluorine and encapsulated fluorine. Free fluorine can be removed directly by acid-base neutralization, but currently there is no mature technology to directly remove encapsulated fluorine from silica. Fluorinated silica powder entering slag dumps causes environmental pollution, while downstream products directly produced from silica powder have high impurity content and poor quality, failing to achieve efficient utilization. Therefore, there is an urgent need for effective ways to utilize the fluorine and silicon resources in fluorinated silica powder. Summary of the Invention

[0003] This invention provides a method for synthesizing Y-type molecular sieves using fluorinated silica powder and recovering fluorine resources. The method of this invention can achieve efficient utilization of fluorine and silicon resources in fluorinated silica powder and prepare high-purity Y-type molecular sieves with few crystal defects.

[0004] A method for synthesizing Y-type molecular sieves using fluorinated silica powder and recovering fluorine resources includes the following steps:

[0005] A) Fluorine-containing silicon powder is mixed with sodium hydroxide solution and heated to react, resulting in a clear solution and sodium fluoride precipitate.

[0006] The silicon and sodium in the clarified solution are calculated as SiO2 and Na2O, with a molar ratio of SiO2 to Na2O of 1.9 to 2.4.

[0007] B) Take a portion of the clear solution and mix it with a high-alkali sodium aluminate solution for activation to obtain an activated directing agent;

[0008] C) Mix the clarified solution, activated directing agent, aluminum sulfate solution, and sodium sulfate solution, and stir to obtain a gel;

[0009] The Na, Al, and Si in the gel are calculated as Na2O, Al2O3, and SiO2, respectively, and the molar ratio of Na2O, Al2O3, SiO2, and H2O is (4.11–5.60):1:(9–10):(120–240).

[0010] D) The gel is heated and crystallized to obtain a Y-type molecular sieve.

[0011] Preferably, the fluorinated silicon powder is a byproduct of the production of anhydrous hydrogen fluoride using the fluorosilicic acid sulfuric acid process.

[0012] Preferably, the mass concentration of the sodium hydroxide solution in step A) is 35-38%.

[0013] Preferably, in step A), the mass ratio of fluorinated silicon powder to sodium hydroxide solution is 1:(1.13-1.18).

[0014] Preferably, the heating reaction temperature in step A) is 90–100°C, and the heating reaction time is 4–8 hours.

[0015] Preferably, the Na, Al, and Si in the activated directing agent are calculated as Na2O, Al2O3, and SiO2, respectively, and the molar ratio of Na2O, Al2O3, SiO2, and H2O is (8.25-17):1:(9-15):(165-360).

[0016] Preferably, in step B), the activated directing agent is activated at 25-25°C for 24-72 hours or at 60-65°C for 0.5-2 hours to obtain the activated directing agent.

[0017] Preferably, the temperature for heating and crystallization in step D) is 90–110°C, and the time for heating and crystallization is 18–24 hours.

[0018] Preferably, in step A), after the heating reaction is completed, the mixture is filtered to obtain a clear solution and a precipitate. The precipitate is dried at 95–105°C to obtain sodium fluoride.

[0019] Preferably, in step D), after the heating and crystallization is completed, the solid product is filtered, washed until the pH is 9-11, and then dried at 100-105°C for 1-3 hours to obtain Y-type molecular sieve.

[0020] This invention provides a method for synthesizing Y-type molecular sieves and recovering fluorine resources using fluorinated silicon powder, comprising the following steps: A) mixing fluorinated silicon powder with sodium hydroxide solution and heating to react, obtaining a clear solution and a precipitate of sodium fluoride; the silicon and sodium in the clear solution are calculated as SiO2 and Na2O, and the molar ratio of SiO2 to Na2O is 1.9 to 2.4; B) mixing a portion of the clear solution with a high-alkali sodium aluminate solution and activating it to obtain an activated directing agent; C) mixing the remaining clear solution, the activated directing agent, aluminum sulfate solution, and sodium sulfate solution and stirring to obtain a gel; the Na, Al, and S in the gel are calculated as Na2O, Al2O3, and SiO2, respectively, and the molar ratio of Na2O, Al2O3, SiO2, and H2O is (4.11 to 5.60): 1: (9 to 10): (120 to 240); D) heating the gel to crystallize it to obtain a Y-type molecular sieve. This invention utilizes fluorinated silicate powder to prepare a low-modulus sodium silicate gel solution, resulting in a significantly reduced fluorine residue (<0.68 wt%), thus significantly improving fluorine-silicon separation efficiency. Organic impurities introduced into the fluorinated silicate powder by the conveyor belt will enter the sodium fluoride precipitate phase during solid-liquid separation of the sodium silicate solution and sodium fluoride precipitate (which can be removed by calcination later), without affecting the quality of the synthesized Y-type molecular sieve powder. The small amount of fluorine remaining in the sodium silicate gel solution can act as a structure-directing agent and electron balancer, which is beneficial for obtaining Y-type molecular sieves with fewer crystal defects. Furthermore, this invention achieves the preparation of high-silica-alumina ratio Y-type molecular sieves in a sodium oxide-rich mother liquor prepared from low-modulus water glass by increasing the silica-alumina ratio and aluminum sulfate content in the mother liquor. Through the preparation and filtration of low-modulus sodium silicate and the small amount of fluorine remaining in the sodium silicate, the removal of organic impurities from the fluorinated silicate powder, efficient separation of fluorine and silicon, and the synthesis of high-purity Y-type molecular sieves with fewer crystal defects are achieved. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 This is a flowchart illustrating the preparation of Y-type molecular sieves and the recovery of fluorine resources using fluorine-containing silicon powder in this invention.

[0023] Figure 2 Photograph (a) and XRD phase diagram (b) of fluorinated silicon powder;

[0024] Figure 3 The XRD patterns of the Y-type molecular sieves synthesized in Examples 1-6 of this invention are shown below.

[0025] Figure 4 This is a SEM image of the Y-type molecular sieve from Example 1 of the present invention;

[0026] Figure 5 This is a SEM image of the Y-type molecular sieve from Example 2 of the present invention;

[0027] Figure 6 This is a SEM image of the Y-type molecular sieve from Example 3 of the present invention;

[0028] Figure 7 This is a SEM image of the Y-type molecular sieve from Example 4 of the present invention;

[0029] Figure 8 This is a SEM image of the Y-type molecular sieve from Example 5 of the present invention;

[0030] Figure 9 This is a SEM image of the Y-type molecular sieve in Example 6 of the present invention. Detailed Implementation

[0031] This invention provides a method for synthesizing Y-type molecular sieves using fluorinated silica powder and recovering fluorine resources, comprising the following steps:

[0032] A) Fluorine-containing silicon powder is mixed with sodium hydroxide solution and heated to react, resulting in a clear solution and sodium fluoride precipitate.

[0033] The silicon and sodium in the clarified solution are calculated as SiO2 and Na2O, with a molar ratio of SiO2 to Na2O of 1.9 to 2.4.

[0034] B) Take a portion of the clear solution and mix it with a high-alkali sodium aluminate solution for activation to obtain an activated directing agent;

[0035] C) Mix the remaining clear solution, activated directing agent, aluminum sulfate solution, and sodium sulfate solution, and stir to obtain a gel;

[0036] The Na, Al, and Si in the gel are calculated as Na2O, Al2O3, and SiO2, respectively, and the molar ratio of Na2O, Al2O3, SiO2, and H2O is (4.11–5.60):1:(9–10):(120–240).

[0037] D) The gel is heated and crystallized to obtain a Y-type molecular sieve.

[0038] In this invention, the fluorinated silicon powder is preferably a byproduct of the production of anhydrous hydrogen fluoride by the fluorosilicic acid sulfuric acid process. The content of fluorine and silicon in the fluorinated silicon powder is not particularly limited. In one embodiment of this invention, the mass fraction of silicon dioxide in the fluorinated silicon powder is preferably 30-40%, more preferably 35-38%, and the mass fraction of F is preferably 8-10%, more preferably 9-10%.

[0039] In this invention, the mass concentration of the sodium hydroxide solution is preferably 35-38%, more preferably 36-37%, such as 35%, 36%, 37%, 38%, preferably within the range of any of the above values ​​as the upper or lower limit. The mass ratio of the fluorinated silicon powder to the sodium hydroxide solution is preferably 1:(1.13-1.18), more preferably 1:(1.14-1.16), such as 1:1.13, 1:1.14, 1:1.15, 1:1.16, 1:1.17, 1:1.18, preferably within the range of any of the above values ​​as the upper or lower limit. In the range of sodium hydroxide solution provided by this invention, sodium hydroxide is in excess, which can ensure complete fluorine precipitation and reaction with amorphous silicon dioxide.

[0040] In this invention, the temperature of the heating reaction is preferably 90-100°C, more preferably 92-98°C, such as 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C, 100°C, preferably within a range where any of the above values ​​is the upper or lower limit; the heating reaction time is preferably 4-8 hours, more preferably 5-6 hours, and the heating reaction is preferably carried out under stirring conditions.

[0041] In this invention, after the heating reaction is completed, the reaction product is allowed to stand and filtered to obtain a clear solution and a precipitate. The precipitate is then dried to obtain sodium fluoride, thus achieving efficient recovery of fluorine resources.

[0042] In this invention, the drying temperature is preferably 95-105°C, more preferably 100-102°C.

[0043] In this invention, the clarified solution is a sodium silicate solution, and the modulus of sodium silicate is 1.9 to 2.4, more preferably 1.9 to 2.3.

[0044] After obtaining a clear solution, the present invention uses a portion of the clear solution to prepare a directing agent. Sodium aluminate is dissolved in sodium hydroxide solution to obtain a high-alkali sodium aluminate solution. Then, the clear solvent is mixed with the high-alkali sodium aluminate to obtain a directing agent. The directing agent is activated to obtain an activated directing agent.

[0045] In this invention, the preferred mass concentration of the sodium hydroxide solution is 36%, and the caustic ratio of the high-alkali sodium aluminate is >10 (caustic ratio (αk) refers to the molar ratio of sodium oxide (Na2O) to aluminum oxide (Al2O3) in the sodium aluminate solution); in the directing agent, Na, Al, and Si elements are calculated as Na2O, Al2O3, and SiO2, respectively, and the preferred molar ratio of Na2O to Al2O3 is (8.25-17):1, more preferably (8.25-17):1. 0.5~15):1, such as 8.25:1, 8.5:1, 9:1, 9.5:1, 10:1, 10.5:1, 11:1, 11.5:1, 12:1, 12.5:1, 13:1, 13.5:1, 14:1, 14.5:1, 15:1, 15.5:1, 16:1, 16.5:1, 17:1, preferably a range of values ​​with any of the above values ​​as the upper or lower limit, the molar ratio of Al2O3 and SiO2 The ratio is 1:(9-15), more preferably 1:(10-14), such as 1:9, 1:9.5, 1:10, 1:10.5, 1:11, 1:11.5, 1:12, 1:12.5, 1:13, 1:13.5, 1:14, 1:14.5, 1:15, preferably within the range of any of the above values ​​as the upper or lower limit. The molar ratio of Al2O3 to H2O is 1:(165-360), more preferably 1:(1 (80~350), such as 1:165, 1:170, 1:180, 1:190, 1:200, 1:210, 1:220, 1:230, 1:240, 1:250, 1:260, 1:270, 1:280, 1:290, 1:300, 1:310, 1:320, 1:330, 1:340, 1:350, 1:360, preferably a range of values ​​with any of the above values ​​as the upper or lower limit.

[0046] In this invention, the activation of the directing agent can be carried out at a constant temperature or variable temperature between 25 and 35°C for 24 to 72 hours, or at a constant temperature of 60 to 65°C for 0.5 to 2 hours.

[0047] After obtaining the activated directing agent, the present invention mixes the activated directing agent, aluminum sulfate solution, sodium aluminate solution and the above-mentioned clarified solution according to the gel composition ratio, and stirs vigorously for 5-10 minutes to obtain a gel.

[0048] In this invention, the gel composition is based on Na2O, Al2O3, and SiO2. The molar ratio of Na2O to Al2O3 is preferably (4.11–5.60):1, more preferably (4.5–5.5):1, such as 4.11:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1, 5:1, 5.1:1, 5.2:1, 5.3:1, 5.4:1, 5.5:1, 5.6:1, preferably within a range where any of the above values ​​is the upper or lower limit; the molar ratio of Al2O3 to SiO2 is preferably 1:(9–10), more preferably 1:(9.2–9.8), such as 1:1. The molar ratio of Al2O3 to H2O is preferably 1:(120-240), more preferably 1:(150-200), such as 1:120, 1:130, 1:140, 1:150, 1:160, 1:170, 1:180, 1:190, 1:200, 1:210, 1:220, 1:230, 1:240, 1:250, 1:260, preferably within the range of values ​​with any of the above values ​​as the upper or lower limit;

[0049] After obtaining the gel, the gel is placed in a polytetrafluoroethylene reactor and directly heated for crystallization without aging. After the crystallization reaction is completed, the gel is filtered, washed until the pH value is 9-11, and then dried at 100-105℃ for 1-3 hours to obtain Y-type molecular sieve.

[0050] In this invention, the temperature for heating and crystallization is preferably 90-110°C, more preferably 95-105°C, such as 90°C, 95°C, 100°C, 105°C, 110°C, preferably a range of values ​​with the above values ​​as the upper or lower limit, and the time for heating and crystallization is preferably 18-24 hours, more preferably 20-24 hours.

[0051] This invention provides a method for synthesizing Y-type molecular sieves and recovering fluorine resources using fluorinated silicon powder, comprising the following steps: A) mixing fluorinated silicon powder with sodium hydroxide solution and heating to react, obtaining a clear solution and a precipitate of sodium fluoride; the silicon and sodium in the clear solution are calculated as SiO2 and Na2O, and the molar ratio of SiO2 to Na2O is 1.9 to 2.4; B) mixing a portion of the clear solution with a high-alkali sodium aluminate solution and activating it to obtain an activated directing agent; C) mixing the remaining clear solution, the activated directing agent, aluminum sulfate solution, and sodium sulfate solution and stirring to obtain a gel; the Na, Al, and S in the gel are calculated as Na2O, Al2O3, and SiO2, respectively, and the molar ratio of Na2O, Al2O3, SiO2, and H2O is (4.11 to 5.60): 1: (9 to 10): (120 to 240); D) heating the gel to crystallize it to obtain a Y-type molecular sieve. This invention utilizes fluorinated silicate powder to prepare a low-modulus sodium silicate gel solution, resulting in a significantly reduced fluorine residue (<0.68 wt%), thus significantly improving fluorine-silicon separation efficiency. Organic impurities introduced into the fluorinated silicate powder by the conveyor belt will enter the sodium fluoride precipitate phase during solid-liquid separation of the sodium silicate solution and sodium fluoride precipitate (which can be removed by calcination later), without affecting the quality of the synthesized Y-type molecular sieve powder. The small amount of fluorine remaining in the sodium silicate gel solution can act as a structure-directing agent and electron balancer, which is beneficial for obtaining Y-type molecular sieves with fewer crystal defects. Furthermore, this invention achieves the preparation of high-silica-alumina ratio Y-type molecular sieves in a sodium oxide-rich mother liquor prepared from low-modulus water glass by increasing the silica-alumina ratio and aluminum sulfate content in the mother liquor. Through the preparation and filtration of low-modulus sodium silicate and the small amount of fluorine remaining in the sodium silicate, the removal of organic impurities from the fluorinated silicate powder, efficient separation of fluorine and silicon, and the synthesis of high-purity Y-type molecular sieves with fewer crystal defects are achieved.

[0052] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, describes a method for synthesizing Y-type molecular sieves using fluorinated silicon powder and recovering fluorine resources, but this should not be construed as limiting the scope of protection of the present invention.

[0053] Example 1

[0054] (1) Recovery of fluorine resources: 1000g of fluorine-containing silicon powder was mixed with sodium hydroxide solution (395g NaOH + 735g water), heated to 100℃, and stirred continuously for 4h. After standing and filtration, a clear solution and a precipitate were obtained. The theoretical modulus of sodium silicate in the clear solution was 2.34, and the measured modulus was 2.19. The precipitate was dried at 120℃ to obtain sodium fluoride. The fluorine recovery rate was calculated to be 99.7%.

[0055] (2) Preparation of the directing agent: The directing agent is composed of 16Na2O:Al2O3:15SiO2:320H2O. Prepare a sodium hydroxide solution (5.229gNaOH+27.27gwater), and dissolve sodium aluminate (1.639g) in the prepared sodium hydroxide solution to obtain a high-alkali sodium aluminate solution. Then add the clear solution (29.622g) prepared in (1) to the high-alkali sodium aluminate solution to obtain the directing agent. The directing agent is aged at 25℃ for 24h.

[0056] (3) Preparation of Y-type molecular sieve gel solution: The gel composition is 5.00Na2O:Al2O3:10SiO2:180H2O. Calculate and weigh according to the gel composition, and add the clarified solution (14.811g) prepared in (1) to the directing agent (2.72g), aluminum sulfate solution (2.321g Al2(SO4)3·18H2O+5.01g water), and sodium aluminate solution (0.554g NaAlO2+5.01g water) respectively, and stir vigorously for 5min.

[0057] (4) Synthesis of Y-type molecular sieve: The Y-type molecular sieve gel solution was placed in a polytetrafluoroethylene reactor and directly heated to 90°C for crystallization without aging. After crystallization for 24 hours, the solution was filtered, washed to pH 9, and dried at 105°C for 2 hours to obtain Y-type molecular sieve raw powder. The relative crystallinity of the Y-type molecular sieve obtained by testing and calculation was 100%.

[0058] Example 2

[0059] (1) Recovery of fluorine resources: 1000g of fluorine-containing silicon powder was mixed with sodium hydroxide solution (395g NaOH + 735g water), heated to 95℃, and stirred continuously for 6h. After standing and filtration, a clear solution and a precipitate were obtained. The theoretical modulus of sodium silicate in the clear solution was 2.34, and the measured modulus was 2.19. The precipitate was dried at 110℃ for 2h to obtain sodium fluoride. The fluorine recovery rate was calculated to be 99.8%.

[0060] (2) Preparation of the directing agent: The directing agent is composed of 16Na2O:Al2O3:15SiO2:320H2O. Prepare a sodium hydroxide solution (5.229g NaOH + 27.27g water), and dissolve sodium aluminate (1.639g) in the prepared sodium hydroxide solution to obtain a high-alkali sodium aluminate solution. Then add the clear solution (29.622g) prepared in (1) to the high-alkali sodium aluminate solution to obtain the directing agent. The directing agent is aged at 35℃ for 24h.

[0061] (3) Preparation of Y-type molecular sieve gel solution: The gel composition is 4.70Na2O:Al2O3:9.5SiO2:180H2O. Calculate and weigh according to the gel composition, and add the clarified solution (14.811g) prepared in (1) to the directing agent (2.72g), aluminum sulfate solution (2.752g Al2(SO4)3·18H2O+4.57g water), and sodium aluminate solution (0.489g NaAlO2+4.57g water) respectively, and stir vigorously for 10min.

[0062] (4) Synthesis of Y-type molecular sieve: The Y-type molecular sieve gel solution was placed in a polytetrafluoroethylene reactor and directly heated to 100°C for crystallization without aging. After crystallization for 18 hours, the solution was filtered, washed to pH 10, and dried at 105°C for 2 hours to obtain Y-type molecular sieve powder. The relative crystallinity of the Y-type molecular sieve obtained by testing and calculation was 105%.

[0063] Example 3

[0064] (1) Recovery of fluorine resources: 1000g of fluorine-containing silicon powder was mixed with sodium hydroxide solution (395g NaOH + 735g water), heated to 100℃, and stirred continuously for 4h. After standing and filtration, a clear solution and a precipitate were obtained. The theoretical modulus of sodium silicate in the clear solution was 2.34, and the measured modulus was 2.19. The precipitate was dried at 105℃ for 2h to obtain sodium fluoride. The fluorine recovery rate was calculated to be 99.7%.

[0065] (2) Preparation of the directing agent: The directing agent is composed of 10.67Na2O:Al2O3:10SiO2:180H2O. Prepare a sodium hydroxide solution (4.909gNaOH+20.06gwater), and dissolve sodium aluminate (2.459g) in the prepared sodium hydroxide solution to obtain a high-alkali sodium aluminate solution. Then add the clear solution (29.622g) prepared in (1) to the high-alkali sodium aluminate solution to obtain the directing agent. The directing agent is aged at 60℃ for 0.5h.

[0066] (3) Preparation of Y-type molecular sieve gel solution: The gel composition is 5.6Na2O:Al2O3:9.5SiO2:220H2O. Calculate and weigh according to the gel composition, and add the clarified solution (14.811g) prepared in (1) to the directing agent (2.72g), aluminum sulfate solution (2.752g Al2(SO4)3·18H2O+16.82g water), and sodium aluminate solution (0.489g NaAlO2+16.82g water) respectively, and stir vigorously for 10min.

[0067] (4) Synthesis of Y-type molecular sieve: The Y-type molecular sieve gel solution was placed in a polytetrafluoroethylene reactor and directly heated to 100°C for crystallization without aging. After crystallization for 24 hours, the solution was filtered, washed to pH 11, and dried at 105°C for 2 hours to obtain Y-type molecular sieve raw powder. The relative crystallinity of the Y-type molecular sieve obtained by testing and calculation was 101%.

[0068] Example 4

[0069] (1) Recovery of fluorine resources: 1000g of fluorine-containing silicon powder was mixed with sodium hydroxide solution (395g NaOH + 735g water), heated to 100℃, and stirred continuously for 4h. After standing and filtration, a clear solution and a precipitate were obtained. The theoretical modulus of sodium silicate in the clear solution was 2.34, and the measured modulus was 2.19. The precipitate was dried at 105℃ for 2h to obtain sodium fluoride. The fluorine recovery rate was calculated to be 99.8%.

[0070] (2) Preparation of the directing agent: The directing agent is composed of 10.67Na2O:Al2O3:10SiO2:180H2O. Prepare a sodium hydroxide solution (4.909gNaOH+20.06gwater), and dissolve sodium aluminate (2.459g) in the prepared sodium hydroxide solution to obtain a high-alkali sodium aluminate solution. Then add the clear solution (29.622g) prepared in (1) to the high-alkali sodium aluminate solution to obtain the directing agent. The directing agent is aged at 60℃ for 2 hours.

[0071] (3) Preparation of Y-type molecular sieve gel solution: The gel composition is 4.36Na2O:Al2O3:8.5SiO2:180H2O. Calculate and weigh according to the gel composition, and add the clarified solution (14.811g) prepared in (1) to the directing agent (2.72g), aluminum sulfate solution (2.529g Al2(SO4)3·18H2O+4.92g water), and sodium aluminate solution (0.713g NaAlO2+4.92g water) respectively, and stir vigorously for 10min.

[0072] (4) Synthesis of Y-type molecular sieve: The Y-type molecular sieve gel solution was placed in a polytetrafluoroethylene reactor and directly heated to 95°C for crystallization without aging for 20 hours. After filtration and washing to pH 10, the Y-type molecular sieve raw powder was obtained by drying at 105°C for 2 hours. The relative crystallinity of the Y-type molecular sieve obtained by testing and calculation was 102%.

[0073] Example 5

[0074] (1) Recovery of fluorine resources: 1000g of fluorine-containing silicon powder was mixed with sodium hydroxide solution (395g NaOH + 735g water), heated to 100℃, and stirred continuously for 4h. After standing and filtration, a clear solution and a precipitate were obtained. The theoretical modulus of sodium silicate in the clear solution was 2.34, and the measured modulus was 2.19. The precipitate was dried at 105℃ for 2h to obtain sodium fluoride. The fluorine recovery rate was calculated to be 99.8%.

[0075] (2) Preparation of the directing agent: The directing agent is composed of 8.25Na2O:Al2O3:11SiO2:165H2O. Prepare a sodium hydroxide solution (4.070gNaOH+19.95gwater), and dissolve sodium aluminate (2.090g) in the prepared sodium hydroxide solution to obtain a high-alkali sodium aluminate solution. Then add the clear solution (22.720g) prepared in (1) to the high-alkali sodium aluminate solution to obtain the directing agent. The directing agent is aged at 60℃ for 2 hours.

[0076] (3) Preparation of Y-type molecular sieve gel solution: The gel composition is 4.70Na2O:Al2O3:9.5SiO2:120H2O. Calculate and weigh according to the gel composition, and add the clarified solution (14.811g) prepared in (1) to the directing agent (2.72g), aluminum sulfate solution (2.752g Al2(SO4)3·18H2O+2.12g water), and sodium aluminate solution (0.489g NaAlO2+2.12g water) respectively, and stir vigorously for 10min.

[0077] (4) Synthesis of Y-type molecular sieve: The Y-type molecular sieve gel solution was placed in a polytetrafluoroethylene reactor and directly heated to 100°C for crystallization without aging. After crystallization for 18 hours, the solution was filtered, washed to pH 9, and dried at 105°C for 2 hours to obtain Y-type molecular sieve powder. The relative crystallinity of the Y-type molecular sieve obtained by testing and calculation was 98%.

[0078] Example 6

[0079] (1) Recovery of fluorine resources: 1000g of fluorine-containing silicon powder was mixed with sodium hydroxide solution (440g NaOH + 735g water), heated to 90℃, and stirred continuously for 8h. After standing and filtration, a clear solution and a precipitate were obtained. The theoretical modulus of sodium silicate in the clear solution was 1.916, and the measured modulus was 1.92. The precipitate was dried at 110℃ for 2h to obtain sodium fluoride. The fluorine recovery rate was calculated to be 99.9%.

[0080] (2) Preparation of the directing agent: The directing agent is composed of 16Na2O:Al2O3:15SiO2:320H2O. Prepare a sodium hydroxide solution (5.666gNaOH+38.06gwater), and dissolve sodium aluminate (1.940g) in the prepared sodium hydroxide solution to obtain a high-alkali sodium aluminate solution. Then add the clear solution (29.622g) prepared in (1) to the high-alkali sodium aluminate solution to obtain the directing agent. The directing agent is aged at 30℃ for 72h.

[0081] (3) Preparation of Y-type molecular sieve gel solution: The gel composition is 4.70Na2O:Al2O3:9.5SiO2:200H2O. Calculate and weigh according to the gel composition, and add the clarified solution (29.622g) prepared in (1) to the directing agent (2.72g), aluminum sulfate solution (10.856g Al2(SO4)3·18H2O+18.96g water), and sodium aluminate solution (0.005g NaAlO2+18.96g water) respectively, and stir vigorously for 10min.

[0082] (4) Synthesis of Y-type molecular sieve: The Y-type molecular sieve gel solution was placed in a polytetrafluoroethylene reactor and directly heated to 100°C for crystallization without aging. After crystallization for 24 hours, the solution was filtered, washed to pH 11, and dried at 105°C for 2 hours to obtain Y-type molecular sieve raw powder. The relative crystallinity of the Y-type molecular sieve obtained by testing and calculation was 99%.

[0083] Comparative Example

[0084] (1) Recovery of fluorine resources: 157.5g of sodium hydroxide was dissolved in 367.5g of deionized water to prepare a 30% alkaline solution. Then, 500g of fluorine-containing silicon powder was mixed with 525g of alkaline solution and heated to 100℃. The mixture was stirred continuously for 4h and then filtered to obtain a clear solution A with a theoretical modulus of 3.869 and a measured modulus of 3.51. The residual F content in the solution was 6.8%, and precipitate B was obtained. Precipitate B was dried at 105℃ for 2h to obtain sodium fluoride. The fluorine recovery rate was calculated to be only 85.8%.

[0085] (2) Preparation of the directing agent: The directing agent is composed of 8.25Na2O:Al2O3:11SiO2:165H2O. Prepare a sodium hydroxide solution (4.070gNaOH+19.95gwater), and dissolve sodium aluminate (2.090g) in the prepared sodium hydroxide solution to obtain a high-alkali sodium aluminate solution. Then add the clear solution (22.720g) prepared in (1) to the high-alkali sodium aluminate solution to obtain the directing agent. The directing agent is aged at 30℃ for 72h.

[0086] (3) Preparation of Y-type molecular sieve gel solution: The gel composition is 4.41Na2O:Al2O3:9.5SiO2:200H2O. Calculate and weigh according to the gel composition, and add the clarified solution (14.811g) prepared in (1) to the directing agent (2.72g), aluminum sulfate solution (2.786g Al2(SO4)3·18H2O+10.1g water), and sodium aluminate solution (0.815g NaAlO2+10.1g water) respectively, and stir vigorously for 10min.

[0087] (4) Synthesis of Y-type molecular sieve: The Y-type molecular sieve gel solution was placed in a polytetrafluoroethylene reactor and directly heated to 100°C for crystallization without aging. After crystallization for 24 hours, the solution was filtered, washed to pH 11, and dried at 105°C for 2 hours to obtain Y-type molecular sieve raw powder. The relative crystallinity of the Y-type molecular sieve obtained by testing and calculation was 88%.

[0088] Table 1. Composition of fluorinated silicon powder in Examples 1-6 (wt%)

[0089]

[0090] Table 2 Chemical composition of Y-type molecular sieves synthesized in Examples 1-6 / wt%

[0091]

[0092] In Table 2, "-" indicates not detected. As shown in Table 2, the molecular sieve products in Examples 1-6 do not contain fluorine. The synthesized Y-type molecular sieve has a SiO2 / Al2O3 molar ratio > 5.0, meeting existing enterprise standards. The fluorine remaining in the clear solution did not have a harmful effect on the molecular sieve. In fact, a small amount of fluorine... - It can also be used as a mineralizer, electronic balancer, structure directing agent, etc., and is not supported in the molecular sieve framework (i.e., it does not exist in the molecular sieve structure), which is beneficial to the synthesis of Y-type molecular sieves.

[0093] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for synthesizing Y-type molecular sieves using fluorinated silica powder and recovering fluorine resources, comprising the following steps: A) Fluorine-containing silicon powder is mixed with sodium hydroxide solution and heated to react, resulting in a clear solution and sodium fluoride precipitate. The silicon and sodium in the clarified solution are calculated as SiO2 and Na2O, with a molar ratio of SiO2 to Na2O of 1.9 to 2.

4. B) Take a portion of the clear solution and mix it with a high-alkali sodium aluminate solution for activation to obtain an activated directing agent; C) Mix the clarified solution, activated directing agent, aluminum sulfate solution, and sodium sulfate solution, and stir to obtain a gel; The Na, Al, and Si in the gel are calculated as Na2O, Al2O3, and SiO2, respectively, and the molar ratio of Na2O, Al2O3, SiO2, and H2O is (4.11–5.60):1:(9–10):(120–240). D) The gel is heated and crystallized to obtain a Y-type molecular sieve.

2. The method for synthesizing Y-type molecular sieves and recovering fluorine resources using fluorine-containing silicon powder according to claim 1, characterized in that, The fluorinated silicon powder is a byproduct of the production of anhydrous hydrogen fluoride using the sulfuric acid process for fluorosilicic acid.

3. The method for recovering fluorine resources and synthesizing type A molecular sieves using fluorine-containing silicon powder according to claim 1, characterized in that, In step A), the mass concentration of the sodium hydroxide solution is 35-38%.

4. The method for recovering fluorine resources and synthesizing type A molecular sieves using fluorine-containing silicon powder according to claim 1, characterized in that, In step A), the mass ratio of fluorinated silicon powder to sodium hydroxide solution is 1:(1.13-1.18).

5. The method for recovering fluorine resources and synthesizing type A molecular sieves using fluorine-containing silicon powder according to claim 1, characterized in that, In step A), the heating reaction temperature is 90–100°C, and the heating reaction time is 4–8 hours.

6. The method for recovering fluorine resources and synthesizing type A molecular sieves using fluorine-containing silicon powder according to claim 1, characterized in that, The activated directing agent contains Na, Al, and Si, calculated as Na2O, Al2O3, and SiO2, respectively, with the molar ratio of Na2O, Al2O3, SiO2, and H2O being (8.25–17):1:(9–15):(165–360).

7. The method for recovering fluorine resources and synthesizing type A molecular sieves using fluorine-containing silicon powder according to claim 1, characterized in that, In step B), the activated directing agent is obtained by activating it at 25-25°C for 24-72 hours or at 60-65°C for 0.5-2 hours.

8. The method for recovering fluorine resources and synthesizing type A molecular sieves using fluorine-containing silicon powder according to claim 1, characterized in that, In step D), the temperature for heating and crystallization is 90–110°C, and the time for heating and crystallization is 18–24 hours.

9. The method for recovering fluorine resources and synthesizing type A molecular sieves using fluorine-containing silicon powder according to claim 1, characterized in that, In step A), after the heating reaction is completed, the mixture is filtered to obtain a clear solution and a precipitate. The precipitate is dried at 95–105°C to obtain sodium fluoride.

10. The method for recovering fluorine resources and synthesizing type A molecular sieves using fluorinated silica powder according to claim 1, characterized in that, In step D), after heating and crystallization, the solid product is filtered, washed until the pH is 9-11, and then dried at 100-105℃ for 1-3 hours to obtain Y-type molecular sieve.

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