Preparation method of silicon-aluminum-phosphorus-calcium multi-component materials

Abstract

This invention relates to the fields of chemical engineering and environmental protection engineering, and discloses a method for preparing a silicon-aluminum-phosphorus-calcium multi-component material and a method for recovering the mother liquor from the synthesis of SAPO-34 molecular sieve. The method includes the following steps: (1) mixing the SAPO-34 molecular sieve synthesis mother liquor with a soluble calcium salt solution, and optionally subjecting the resulting suspension to a hydrothermal reaction; (2) performing solid-liquid separation on the product from step (1), and sequentially washing, drying, and optionally calcining the separated solid phase to obtain the silicon-aluminum-phosphorus-calcium multi-component material; wherein the amount of the soluble calcium salt solution (calculated as Ca) relative to the SAPO-34 molecular sieve synthesis mother liquor is 20-100 mg / g mother liquor. This invention utilizes waste SAPO-34 molecular sieve synthesis mother liquor to prepare the silicon-aluminum-phosphorus-calcium multi-component material and then recovers triethylamine, resulting in high material utilization, a simple process flow, green energy saving, low cost, and ease of implementation.

Description

Technical Field

[0001] This invention relates to the fields of chemical engineering and environmental protection engineering, specifically to a method for preparing a silicon-aluminum-phosphorus-calcium multi-element material and a method for recovering the mother liquor from the synthesis of SAPO-34 molecular sieve. Background Technology

[0002] SAPO-34 molecular sieves possess excellent hydrothermal stability and good catalytic performance, making them one of the most important types of phosphorus-aluminum molecular sieves. They are widely used in methanol-to-olefins (MTO) processes. However, in the production of SAPO-34 molecular sieves, organic amines such as triethylamine, used as template agents, cannot be completely consumed, and various other inorganic salts rich in Al, P, and Si elements also remain in the synthesis mother liquor. Discharging this crystallization mother liquor into the environment would not only cause serious pollution but also waste a large amount of usable resources. Currently, the discharge of molecular sieve synthesis mother liquor is restricted by national environmental protection regulations. Therefore, the resource utilization of synthetic molecular sieve mother liquor is of great significance from both resource utilization and environmental protection perspectives.

[0003] The main way to reuse the existing SAPO-34 molecular sieve synthesis mother liquor is to recycle its effective components for the synthesis and preparation of the molecular sieve or to make other valuable products to reduce emissions and waste. Chinese patent CN102992349B recovers the crystallization mother liquor and replenishes it with silicon, aluminum, and phosphorus sources, adds matrix materials, binders, pore-forming agents, etc., and prepares microsphere powder through spray molding. After calcination, it is combined with an aqueous solution of an organic template agent for in-situ crystallization to prepare spherical SAPO-34 molecular sieve catalysts for fluidized bed devices, achieving the reuse of the mother liquor. This method requires spray molding and calcination crystallization after replenishing raw materials and additives, making the process complex. CN105668587B treats the crystallization mother liquor as a whole. First, a small amount of slurry is prepared as a "starter," and then a large amount of concentrated mother liquor is added to the raw materials to form a gel mixture. The volume of this concentrated mother liquor is 25%-50% of the volume of the recovered mother liquor. This cycle is repeated to synthesize SAPO-34 molecular sieves. This method involves concentrating the mother liquor before use, but removing a large amount of water increases energy consumption and reduces economic efficiency. Sinopec Catalyst Nanjing Branch proposed a scheme to efficiently recover triethylamine by alkali modification of SAPO-34 molecular sieve crystallization mother liquor and vacuum distillation. However, elements such as P, Al, and Si are discarded in the form of solid residue, resulting in low utilization of mother liquor resources (Energy and Chemical Industry, 2020, 41(04):71-74). Chinese patent CN106542623B first fractionates the organic template agent in the crystallization mother liquor, then acid-leaches the precipitated solid material, and obtains polyphosphate aluminum sulfate flocculant by controlling the changes in the molar ratio of P / Al and basicity through hydrolysis, polymerization, and aging. This scheme achieves effective recycling of crystallization mother liquor, but the process is still too complex, and its practical application is questionable.

[0004] Given the current situation, designing a simple and efficient route for utilizing the mother liquor from the synthesis of SAPO-34 molecular sieve remains an important task that urgently needs to be completed. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a new method for the resource utilization of SAPO-34 molecular sieve synthesis mother liquor. This method uses waste SAPO-34 molecular sieve synthesis mother liquor to prepare silicon-aluminum-phosphorus-calcium multi-component materials and then recovers triethylamine. The material utilization rate is high, the process is simple, green and energy-saving, low in cost and easy to implement.

[0006] To achieve the above objectives, the present invention provides a method for preparing a silicon-aluminum-phosphorus-calcium ternary material, the method comprising the following steps:

[0007] (1) The mother liquor of SAPO-34 molecular sieve synthesis was mixed with a soluble calcium salt solution, and the resulting suspension was subjected to an optional hydrothermal reaction;

[0008] (2) The product in step (1) is subjected to solid-liquid separation, and the solid phase separated by solid-liquid separation is washed, dried and optionally calcined to obtain silicon-aluminum-phosphorus-calcium multi-component materials.

[0009] The amount of the soluble calcium salt solution (calculated as Ca) relative to the mother liquor of SAPO-34 molecular sieve synthesis is 20-100 mg / g mother liquor.

[0010] Preferably, the SAPO-34 molecular sieve crystallization mother liquor contains 0.5-10 wt% aluminum, 0-5 wt% silicon, and 1-20 wt% phosphorus.

[0011] Preferably, the triethylamine content in the SAPO-34 molecular sieve crystallization mother liquor is 2-40 wt%.

[0012] Preferably, the amount of the soluble calcium salt solution, calculated as Ca, relative to the SAPO-34 molecular sieve synthesis mother liquor is 40-90 mg / g mother liquor.

[0013] Preferably, the method further includes: diluting and adjusting the pH of the SAPO-34 molecular sieve synthesis mother liquor before mixing it with the soluble calcium salt solution.

[0014] Preferably, the volume ratio of water added during dilution to the SAPO-34 molecular sieve synthesis mother liquor is 0-10.

[0015] Preferably, the pH of the SAPO-34 molecular sieve synthesis mother liquor is adjusted to 8-14.

[0016] Preferably, the pH adjusting agent is one or more of ammonia, sodium hydroxide, and potassium hydroxide.

[0017] Preferably, the soluble calcium salt in the soluble calcium salt solution is calcium chloride and / or calcium nitrate.

[0018] Preferably, the soluble calcium salt is calcium chloride, and the concentration of the calcium chloride solution is 1-43 wt%.

[0019] Preferably, the method further includes adjusting the pH of the calcium chloride solution to 7-14 before mixing the SAPO-34 molecular sieve synthesis mother liquor with the calcium chloride solution.

[0020] Preferably, in step (1), the SAPO-34 molecular sieve synthesis mother liquor and the soluble calcium salt solution are mixed by adding the SAPO-34 molecular sieve synthesis mother liquor dropwise into the soluble calcium salt solution while stirring.

[0021] Preferably, the dropping rate of the SAPO-34 molecular sieve synthesis mother liquor is 0.05-5 g / min.

[0022] Preferably, the stirring speed is 100-900 r / min.

[0023] Preferably, the method further includes adjusting the pH of the obtained suspension to 8-14 before carrying out the hydrothermal reaction.

[0024] Preferably, the hydrothermal reaction temperature is 50-200℃ and the time is 0-90h.

[0025] Preferably, the solid-liquid separation method is vacuum filtration or high-speed centrifugation.

[0026] Preferably, the drying temperature is 50-150℃ and the time is 2-12h.

[0027] Preferably, the roasting temperature is 300-700℃ and the time is 0-8h.

[0028] The second aspect of the present invention provides the application of the silicon-aluminum-phosphorus-calcium multi-element material prepared by the preparation method of the present invention in ion adsorption in water, preparation of inorganic antibacterial agents, preparation of artificial joint prostheses, or preparation of catalyst carriers.

[0029] A third aspect of the present invention provides a method for recovering SAPO-34 molecular sieve synthesis mother liquor, the method comprising preparing silicon-aluminum-phosphorus-calcium multi-component materials using SAPO-34 molecular sieve synthesis mother liquor according to the preparation method of the present invention described above.

[0030] Preferably, the method further includes: recovering triethylamine from the liquid phase product of solid-liquid separation.

[0031] Preferably, triethylamine is recovered by one or more of the following methods: atmospheric distillation, vacuum distillation, extraction, and adsorption.

[0032] Through the above technical solution, the method of this invention can realize the resource utilization of SAPO-34 molecular sieve crystallization mother liquor, with high material utilization rate, simple process flow, green and energy-saving, low cost and easy implementation. After mother liquor treatment, the content of Al, Si and P is significantly reduced, achieving emission standards. The prepared silicon-aluminum-phosphorus-calcium multi-element material can be applied in multiple fields such as adsorbents, antibacterial agents, joint prostheses and multifunctional catalyst carriers, with excellent performance and high added value. The separated triethylamine is reused as a template agent in the preparation process, effectively reducing the production cost of SAPO-34 molecular sieve. In summary, this resource utilization path has significant environmental and economic benefits. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the method for resource utilization of SAPO-34 molecular sieve synthesis mother liquor in this invention;

[0034] Figure 2 The XRD patterns of the solid products obtained under different calcium source inputs in this invention after drying are shown.

[0035] Figure 3 The XRD patterns of the solid products obtained under different calcium source inputs in this invention after calcination are shown.

[0036] Figure 4 This is a TEM image of the solid product obtained when the calcium source input is 65 mg Ca / g mother liquor and the crystallization time is 70 h in this invention. Detailed Implementation

[0037] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0038] The first aspect of this invention provides a method for preparing a silicon-aluminum-phosphorus-calcium ternary material, the method comprising the following steps:

[0039] (1) The mother liquor of SAPO-34 molecular sieve synthesis was mixed with a soluble calcium salt solution, and the resulting suspension was subjected to an optional hydrothermal reaction;

[0040] (2) The product in step (1) is subjected to solid-liquid separation, and the solid phase separated by solid-liquid separation is washed, dried and optionally calcined to obtain silicon-aluminum-phosphorus-calcium multi-component materials.

[0041] The amount of the soluble calcium salt solution (calculated as Ca) relative to the mother liquor of SAPO-34 molecular sieve synthesis is 20-100 mg / g mother liquor.

[0042] In the method of this invention, there is no particular limitation on the SAPO-34 molecular sieve synthesis mother liquor, as long as it is the crystallization mother liquor obtained during the synthesis of SAPO-34 molecular sieve. For example, the aluminum content in the SAPO-34 molecular sieve crystallization mother liquor can be 0.5-10 wt%, the silicon content can be 0-5 wt%, and the phosphorus content can be 1-20 wt%. Furthermore, the SAPO-34 molecular sieve crystallization mother liquor may also contain triethylamine as a template agent, for example, the triethylamine content can be 2-40 wt%. By reusing the above-mentioned SAPO-34 molecular sieve synthesis mother liquor, the silicon-aluminum-phosphorus-calcium multi-component material of this invention can be prepared.

[0043] According to the present invention, in step (1), in order to obtain a silicon-aluminum-phosphorus-calcium ternary material with better performance, preferably, the amount of the soluble calcium salt solution (calculated as Ca) relative to the SAPO-34 molecular sieve synthesis mother liquor is 20-100 mg / g mother liquor, more preferably 40-90 mg / g mother liquor. Furthermore, the amount of the soluble calcium salt solution mentioned above is based on the SAPO-34 molecular sieve synthesis mother liquor; if the SAPO-34 molecular sieve synthesis mother liquor is diluted, it is based on the SAPO-34 molecular sieve synthesis mother liquor before dilution.

[0044] From the perspective of improving the crystallinity and adsorption performance of ferrosilicon-aluminum-phosphorus-calcium ternary materials, the method preferably further includes: diluting and adjusting the pH of the SAPO-34 molecular sieve synthesis mother liquor before mixing it with the soluble calcium salt solution. The volume ratio of water added during dilution to the SAPO-34 molecular sieve synthesis mother liquor can be 0-10, preferably 0.5-5, and more preferably 0.8-2. pH adjustment can be performed using one or more of ammonia, sodium hydroxide, and potassium hydroxide. Preferably, the pH of the SAPO-34 molecular sieve synthesis mother liquor is adjusted to 8-14, more preferably 10-12, and more preferably 10.5-11.5. By using the SAPO-34 molecular sieve synthesis mother liquor with the above concentration and pH, the crystallinity and adsorption performance of the ferrosilicon-aluminum-phosphorus-calcium ternary materials can be improved.

[0045] According to the present invention, in step (1), the soluble calcium salt used is not particularly limited, such as calcium chloride, calcium nitrate, etc., preferably calcium chloride, and the concentration of the calcium chloride solution can be 1-43 wt%, preferably 2-20 wt%, more preferably 5-10 wt%. From the perspective of improving the crystallinity and adsorption performance of the silica-aluminophosphorus-calcium multi-element material, the method preferably further includes: before mixing the SAPO-34 molecular sieve synthesis mother liquor with the calcium chloride solution, adjusting the pH of the calcium chloride solution to 7-14, preferably 10-12, more preferably 10.5-11.5.

[0046] According to the present invention, in step (1), the mixing of the SAPO-34 molecular sieve synthesis mother liquor and the soluble calcium salt solution is preferably carried out by adding the SAPO-34 molecular sieve synthesis mother liquor dropwise to the soluble calcium salt solution under stirring. Preferably, the dropping rate of the SAPO-34 molecular sieve synthesis mother liquor is 0.05-5 g / min, more preferably 0.1-4 g / min, and more preferably 2-3 g / min. Furthermore, the stirring speed can be 100-900 r / min.

[0047] From the perspective of improving the crystallinity and adsorption performance of silicon-aluminum-phosphorus-calcium multi-component materials, this method also includes adjusting the pH of the obtained suspension to 8-14 before carrying out a hydrothermal reaction.

[0048] According to the present invention, in step (1), the hydrothermal reaction may or may not be carried out as needed. By carrying out the hydrothermal reaction, silicon-aluminum-phosphorus-calcium multi-component materials such as a mixture of silicon-aluminum-doped hydroxyapatite and silicon-doped fibrous calcium aluminate, or a mixture of silicon-aluminum-doped hydroxyapatite and pseudoboehmite can be obtained. Therefore, it is preferred to carry out the hydrothermal reaction. The hydrothermal reaction only needs to crystallize the suspension. The conditions for the hydrothermal reaction are, for example, a temperature of 50-200°C and a time of 0-90h; preferably, a temperature of 100-200°C and a time of 10-70h.

[0049] According to the present invention, in step (2), the solid-liquid separation, washing, drying, and optional calcination are not particularly limited in their methods. Specifically, the solid-liquid separation method can be vacuum filtration or high-speed centrifugation. The washing solution is preferably neutral. The drying conditions may include: a temperature of 50-150°C and a time of 2-12 hours; preferably, a temperature of 80-120°C and a time of 6-12 hours. Calcination may or may not be performed as needed; calcination can yield silicon-aluminum doped hydroxyapatite and other silicon-aluminum-phosphorus-calcium multi-component materials. The calcination conditions may include: a temperature of 300-700°C and a time of 0-8 hours; preferably, a temperature of 500-650°C and a time of 2-8 hours.

[0050] The silicon-aluminum-phosphorus-calcium multi-component material obtained by the above preparation method can be, for example, an amorphous silicon-aluminum-phosphorus-calcium compound, silicon-aluminum doped hydroxyapatite, silicon-doped fibrous calcium aluminate, or a mixture of the above materials with boehmite, or any combination of two or three of the above materials.

[0051] According to a particularly preferred embodiment of the present invention, such as Figure 1 As shown, the preparation method includes the following steps:

[0052] (a) Dilute the SAPO-34 molecular sieve synthesis mother liquor and adjust its pH to 8-14;

[0053] (b) Mix the solution obtained in step (a) with calcium chloride solution to obtain a suspension;

[0054] (c) Adjust the pH of the suspension obtained in step (b) to 8-14 and subject it to a hydrothermal reaction;

[0055] (d) Perform solid-liquid separation on the product obtained from the hydrothermal reaction in step (c);

[0056] (e) The solid products separated from the liquid are washed, dried and optionally calcined in sequence to obtain silicon-aluminum-phosphorus-calcium multi-component materials.

[0057] Preferably, in step (b), the amount of the calcium chloride solution (calculated as Ca) relative to the SAPO-34 molecular sieve synthesis mother liquor is 20-100 mg / g mother liquor.

[0058] Preferably, in step (b), before mixing the SAPO-34 molecular sieve synthesis mother liquor with the calcium chloride solution, the pH of the calcium chloride solution is adjusted to 7-14.

[0059] A second aspect of this invention provides the application of the silicon-aluminum-phosphorus-calcium multi-element material prepared by the above-described preparation method in ion adsorption in water, preparation of inorganic antibacterial agents, preparation of artificial joint prostheses, or preparation of catalyst supports. Specifically, the ion adsorption in water can be, for example, the adsorption of fluoride ions or heavy metal ions, and the inorganic antibacterial agent can be, for example, an inorganic antibacterial agent containing specific metal ions.

[0060] A third aspect of the present invention provides a method for recovering the mother liquor from the synthesis of SAPO-34 molecular sieve, characterized in that the method includes preparing a silicon-aluminum-phosphorus-calcium multi-component material using the SAPO-34 molecular sieve mother liquor according to the preparation method of the present invention described above.

[0061] To recover triethylamine from the mother liquor of SAPO-34 molecular sieve synthesis, the method may further include: recovering triethylamine from the liquid phase product after solid-liquid separation. Preferably, the recovery of triethylamine is carried out by one or more of the following methods: atmospheric distillation, vacuum distillation, extraction, and adsorption, as long as triethylamine can be recovered.

[0062] The present invention will be described in detail below through examples. In the following examples, XRD patterns were obtained using a Rigaku SmartLab SE X-ray diffractometer (Japan); TEM patterns were obtained using a FEI Talos F200S transmission electron microscope (USA); the SAPO-34 molecular sieve crystallization mother liquor was obtained from the Nanjing Branch of Sinopec Catalyst Co., Ltd., and contained approximately 1.46 wt% aluminum, approximately 0.04 wt% silicon, approximately 3.14 wt% phosphorus, and approximately 11.5 wt% triethylamine.

[0063] Example 1-1

[0064] according to Figure 1 The process is as follows: 12.00 g of SAPO-34 molecular sieve crystallization mother liquor was taken and added to 13.00 g of deionized water. The mixture was stirred evenly, and the pH was adjusted to 11 using sodium hydroxide solution (NaOH mass fraction of 20 wt%). Separately, 1.43 g of anhydrous calcium chloride (equivalent to 43 mg Ca / g mother liquor) was dissolved in 25.00 g of deionized water and stirred evenly. The pH was adjusted to 11 using sodium hydroxide solution. The diluted mother liquor was slowly added dropwise to the calcium chloride solution over 10 minutes. The resulting suspension was stirred thoroughly, and the pH was adjusted to 10.4 using sodium hydroxide solution. The suspension was transferred to a hydrothermal reactor and crystallized in an oven at 120 °C for 70 h. After removal, the solid and liquid components were separated using a high-speed centrifuge. The solid product was washed with deionized water until neutral and dried at 100 °C for 12 h to obtain a silicon-aluminum-phosphorus-calcium multi-component material. The liquid product was used to recover triethylamine by distillation.

[0065] Examples 1-2 and 1-3

[0066] The SAPO-34 molecular sieve synthesis mother liquor was treated according to the method in Example 1-1, except that the amount of anhydrous calcium chloride added was changed to 2.16 g and 2.87 g (equivalent to 65 mg Ca / g mother liquor and 86 mg Ca / g mother liquor, respectively).

[0067] Test Example 1

[0068] The XRD patterns of the silicon-aluminum-phosphorus-calcium multi-component materials prepared in Examples 1-1 to 1-3 were determined, and the results are as follows: Figure 2 As shown.

[0069] from Figure 2The results showed that at low calcium input (43 mg Ca / g mother liquor), the solid product contained two crystal forms: fibrous calcium aluminate and hydroxyapatite. At high calcium input (65 mg Ca / g mother liquor and 86 mg Ca / g mother liquor), the solid product was a mixture of hydroxyapatite and pseudoboehmite.

[0070] Examples 2-1 to 2-3

[0071] SAPO-34 molecular sieve synthesis mother liquor was treated according to the methods in Examples 1-1 to 1-3, with the only difference being that the solid product was dried and then calcined in a muffle furnace at 550°C for 4 hours.

[0072] Test Example 2

[0073] The XRD patterns of the silicon-aluminum-phosphorus-calcium multi-component materials prepared in Examples 2-1 to 2-3 were determined, and the results are as follows: Figure 3 As shown.

[0074] from Figure 2 The results showed that when the calcium input was low (43 mg Ca / g mother liquor), the solid product was hydroxyapatite with low crystallinity. As the calcium input increased (e.g., 65 mg Ca / g mother liquor and 86 mg Ca / g mother liquor), the crystallinity of the hydroxyapatite product tended to be more complete.

[0075] Example 3-1

[0076] according to Figure 1 The process is as follows: 12.00g of SAPO-34 molecular sieve crystallization mother liquor was taken and added to 13.00g of deionized water. The mixture was stirred evenly, and the pH was adjusted to 11 using ammonia. Separately, 2.16g of anhydrous calcium chloride (equivalent to 65mgCa / g mother liquor) was dissolved in 25.00g of deionized water and stirred evenly. The pH was adjusted to 11 using ammonia. The diluted mother liquor was slowly added dropwise to the calcium chloride solution over 10 minutes. The resulting suspension was stirred thoroughly, and the pH was adjusted to 10.4 using ammonia. The suspension was transferred to a hydrothermal reactor and crystallized in a 120℃ oven for 70 hours. After removal, the solid and liquid components were separated using a high-speed centrifuge. The solid product was washed with deionized water until neutral, dried at 100℃ for 12 hours, and then calcined in a muffle furnace at 550℃ for 4 hours to obtain a silicon-aluminum-phosphorus-calcium multi-component material. The liquid product was used to recover triethylamine by distillation.

[0077] Examples 3-2 to 3-3

[0078] The mother liquor for the synthesis of SAPO-34 molecular sieve was treated according to the method in Example 3-1, except that the crystallization time was changed to 20h and 10h respectively.

[0079] Test Example 3

[0080] The XRD patterns of the silicon-aluminum-phosphorus-calcium multi-component materials prepared in Examples 3-1 to 3-3 were measured. The results showed that the solid products obtained with crystallization times between 10 and 70 h were all hydroxyapatite with high crystallinity.

[0081] Figure 4 The image shows a TEM image of the hydroxyapatite product after 70 hours of crystallization, which consists of rod-shaped grains with lengths in the nanometer range. Under these reaction conditions, the concentrations of P, Al, and Si in the liquid product are significantly reduced to 0.6, 1.1, and 0.4 mg / L, respectively.

[0082] Example 4-1

[0083] according to Figure 1 The process is as follows: 12.00 g of SAPO-34 molecular sieve crystallization mother liquor was taken and added to 13.00 g of deionized water. The mixture was stirred evenly and the pH was adjusted to 11 using ammonia. Separately, 1.43 g of anhydrous calcium chloride (equivalent to 43 mg Ca / g mother liquor) was dissolved in 25.00 g of deionized water and stirred evenly. The pH was adjusted to 11 using ammonia. The diluted mother liquor was slowly added dropwise to the calcium chloride solution over 10 minutes, and the resulting suspension was stirred thoroughly. The suspension was then separated into solid and liquid components using a high-speed centrifuge. The solid product was washed with deionized water until neutral, dried at 100 °C for 12 h, and then calcined in a muffle furnace at 550 °C for 4 h to obtain a silicon-aluminum-phosphorus-calcium multi-component material. The liquid product was then distilled to recover triethylamine.

[0084] Example 4-2

[0085] The SAPO-34 molecular sieve synthesis mother liquor was treated according to the method in Example 4, except that the crystallization mother liquor was not diluted and the pH was not adjusted throughout the process.

[0086] The XRD signals of the solid products obtained by the methods in Examples 4-1 and 4-2 above show that they are all amorphous silicon-aluminum-phosphorus-calcium multi-element materials.

[0087] Test Example 4

[0088] 0.2g of the solid product obtained in Examples 3-1 to 3-3 was added to 40mL of a 30mg / L fluoride ion solution. The mixture was stirred and adsorbed at a constant temperature of 25°C for 60min. After the adsorption was completed, solid-liquid separation was achieved by high-speed centrifugation. The concentration of fluoride ions in the supernatant was measured using a fluoride ion selective electrode, and the corresponding fluoride removal capacity was calculated, as shown in Table 1.

[0089] Table 1. Defluorination capacity of solid products obtained at different crystallization times

[0090] Crystallization time (h) 10 20 70 Fluoride removal capacity (mg / g) 4.35 3.58 3.34

[0091] As shown in Table 1, the silica-alumina-phosphorus-calcium multi-component material generated after treatment with SAPO-34 molecular sieve crystallization mother liquor exhibits excellent defluorination performance. When the crystallization time is 10 h, the defluorination capacity can reach 4.35 mg / g.

[0092] Test Example 5

[0093] The solid products obtained in Examples 4-1 and 4-2 were used as adsorbents, and the defluorination capacity test was performed according to the method in Test Example 4.

[0094] The defluorination capacities of the two amorphous silica-alumina-phosphorus-calcium ternary materials in Examples 4-1 and 4-2 were 3.11 and 3.68 mg / g, respectively, indicating that the solid products after treatment with the crystallization mother liquor of SAPO-34 molecular sieve also have certain defluorination activity under non-crystallization conditions.

[0095] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a silicon-aluminum-phosphorus-calcium ternary material, characterized in that, The method includes the following steps: (1) The mother liquor of SAPO-34 molecular sieve synthesis was mixed with a soluble calcium salt solution, and the resulting suspension was subjected to a hydrothermal reaction; (2) The product in step (1) is subjected to solid-liquid separation, and the solid phase separated by solid-liquid separation is washed, dried and calcined in sequence to obtain silicon-aluminum-phosphorus-calcium multi-component materials; The amount of the soluble calcium salt solution, calculated as Ca, relative to the mother liquor of SAPO-34 molecular sieve synthesis is 40-90 mg / g mother liquor. The triethylamine content in the SAPO-34 molecular sieve crystallization mother liquor is 2-40 wt%. The hydrothermal reaction temperature is 100-200℃, and the time is 10-70h; The method further includes: diluting and adjusting the pH of the SAPO-34 molecular sieve synthesis mother liquor before mixing it with the soluble calcium salt solution; adjusting the pH of the SAPO-34 molecular sieve synthesis mother liquor to 8-14; The method also includes adjusting the pH of the resulting suspension to 8-14 before carrying out the hydrothermal reaction.

2. The preparation method according to claim 1, wherein, The SAPO-34 molecular sieve crystallization mother liquor contains 0.5-10 wt% aluminum, 0-5 wt% silicon, and 1-20 wt% phosphorus.

3. The preparation method according to claim 1, wherein, The volume ratio of water added during dilution to the SAPO-34 molecular sieve synthesis mother liquor is 0-10.

4. The preparation method according to claim 1, wherein, pH adjusting agents can be one or more of ammonia, sodium hydroxide, and potassium hydroxide.

5. The preparation method according to claim 1, wherein, The soluble calcium salt in the soluble calcium salt solution is calcium chloride and / or calcium nitrate.

6. The preparation method according to claim 5, wherein, The soluble calcium salt is calcium chloride, and the concentration of the calcium chloride solution is 1-43 wt%. And / or, the method further includes: adjusting the pH of the calcium chloride solution to 7-14 before mixing the SAPO-34 molecular sieve synthesis mother liquor with the calcium chloride solution.

7. The preparation method according to claim 1, wherein, In step (1), the SAPO-34 molecular sieve synthesis mother liquor and the soluble calcium salt solution are mixed by adding the SAPO-34 molecular sieve synthesis mother liquor dropwise into the soluble calcium salt solution while stirring.

8. The preparation method according to claim 7, wherein, The dropping rate of the SAPO-34 molecular sieve synthesis mother liquor is 0.05-5 g / min; And / or, the stirring speed is 100-900 r / min.

9. The preparation method according to any one of claims 1-8, wherein, The solid-liquid separation method is vacuum filtration or high-speed centrifugation.

10. The preparation method according to any one of claims 1-8, wherein, The drying temperature is 50-150℃, and the time is 2-12 hours; And / or, the roasting temperature is 300-700℃, and the time is 0-8h.

11. The application of the silicon-aluminum-phosphorus-calcium multi-element material prepared by any one of claims 1-10 in ion adsorption in water, preparation of inorganic antibacterial agents, preparation of artificial joint prostheses, or preparation of catalyst carriers.

12. A method for recovering mother liquor from the synthesis of SAPO-34 molecular sieve, characterized in that, The method includes preparing a silica-alumina-phosphorus-calcium multi-component material using a SAPO-34 molecular sieve synthesis mother liquor according to any one of claims 1-10.

13. The recycling method according to claim 12, wherein, The method also includes recovering triethylamine from the liquid phase product of solid-liquid separation.

14. The recycling method according to claim 13, wherein, The recovery of triethylamine can be carried out by one or more of the following methods: atmospheric distillation, vacuum distillation, extraction, and adsorption.

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