Synthesis method of silicon-aluminum-phosphorus composite oxide, composite and application

Abstract

The invention discloses a synthesis method of a silicon-aluminum-phosphorus composite oxide and a compound and application thereof, and the synthesis method comprises the following steps: step 1, heating and stirring phosphoric acid, and adding an aluminum source and water to form an aluminum phosphate suspension; 2, dissolving a silicon source to obtain a silicon source solution; and 3, mixing the aluminum phosphate suspension and the silicon source solution, drying, and calcining to obtain the silicon-aluminum-phosphorus composite oxide. According to the method, the SAP preparation process is short in time consumption, secondary waste gas such as hydrogen chloride cannot be generated, rapid and simple large-scale production can be achieved, the prepared silicon-aluminum-phosphorus composite oxide can convert lithium chloride into Li3PO4 and LixAlxSi (1-x) O2-x, the chlorine element content in the product is lower than 10000 ppm, the requirement for follow-up glass curing can be met, and remarkable progressive significance is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic amorphous materials, and in particular to a synthesis method of a silicon-aluminum-phosphorus composite oxide, the composite and application thereof. Background Art

[0002] The Korea Atomic Energy Research Institute has developed a silicon-aluminum-phosphorus composite oxide called "SAP", which is used as a dechlorination agent to try to convert waste molten salt into a composite product of phosphate and silicate, which is further used for glass solidification. SAP is an inorganic composite material. The SAP dechlorination treatment removes chloride ions from the waste molten salt system and ensures that the radioactive elements in the waste molten salt are retained in the system.

[0003] SAP is an effective dechlorination material for chlorine-containing waste molten salt. SAP is usually prepared by a sol-gel method, with tetraethyl orthosilicate (TEOS), aluminum chloride (AlCl3·6H2O) and phosphoric acid (H3PO4) used as silicon, aluminum and phosphorus sources, respectively. However, the preparation of SAP by the sol-gel method is time-consuming and accompanied by the generation of secondary waste gases such as hydrogen chloride, and it is difficult to produce it on a large scale industrially.

[0004] Therefore, it is necessary to develop a new synthesis method of silicon-aluminum-phosphorus composite oxides that can be quickly and simply mass-produced on the basis of efficient dechlorination capabilities. Summary of the invention

[0005] The present invention aims to solve the problem that the preparation process of SAP by sol-gel method is time-consuming, accompanied by the generation of secondary waste gas such as hydrogen chloride, and difficult to be industrialized on a large scale, and provides a synthesis method of silicon-aluminum-phosphorus composite oxide, the composite and its application.

[0006] In order to achieve the above technical objectives, the technical solution provided by the present invention is:

[0007] A method for synthesizing a silicon-aluminum-phosphorus composite oxide, characterized in that it comprises the following steps:

[0008] Step 1: Heat and stir phosphoric acid, and add an aluminum source and water to form an aluminum phosphate suspension;

[0009] Step 2: dissolving the silicon source to obtain a silicon source solution;

[0010] Step 3: Mix the aluminum phosphate suspension and the silicon source solution, dry and calcine to obtain a silicon-aluminum-phosphorus composite oxide.

[0011] Furthermore, the aluminum source is one or more of pseudo-boehmite, aluminum hydroxide, and activated alumina.

[0012] Furthermore, the silicon source is one or more of silica sol and fumed silica.

[0013] Furthermore, in step 1, the phosphoric acid is heated at a temperature of 20 to 100°C.

[0014] Furthermore, in step 3, the calcination temperature is 500° C. to 800° C., and the calcination time is greater than 2 hours.

[0015] The present invention also provides a silicon-aluminum-phosphorus composite oxide, which is a composite of SiO2, Al2O3 and P2O5.

[0016] Furthermore, the molar ratio of silicon, aluminum and phosphorus is Si:Al:P=1:0.5~2:0.5~3.

[0017] The present invention also provides an application of silicon-aluminum-phosphorus composite oxide in removing chlorine from metal chloride. First, metal chloride and silicon-aluminum-phosphorus composite oxide are uniformly mixed in a certain proportion, and then the mixture is heated to 600-800° C., a dechlorination reaction occurs, and the chlorine element is converted into chlorine gas and leaves the mixture system. After the reaction is completed, the mixture is cooled to room temperature to obtain a mixture from which the chlorine element is removed. The chlorine content in the mixture is less than 10,000 ppm.

[0018] The present invention has the following beneficial effects:

[0019] 1. The method for preparing SAP of the present invention is different from the sol-gel method reported in the literature. Instead, it adopts a direct mixing method, which is simple and efficient, and saves a lot of aging reaction time. At the same time, the raw materials used in the present invention do not contain chloride ions. Unlike the traditional sol-gel method, the synthesis process is not accompanied by the generation of secondary waste gases such as hydrogen chloride, and the equipment corrosion problem in the synthesis process is reduced, which enables fast and simple large-scale production.

[0020] 2. The molar ratio of silicon, aluminum and phosphorus in the present invention is Si:Al:P=1:0.5-2:0.5-3, which is conducive to the formation of chemical bonds between Al and P.

[0021] 3. The phosphoric acid heating temperature of the present invention is 20-100° C., which can ensure that the phosphorus source and the aluminum source are fully reacted and mixed, and ensure operational safety and energy economy.

[0022] 4. The aluminum phosphate suspension and silicon source solution of the present invention are dried and calcined for more than 2 hours at a temperature ranging from 500°C to 800°C. During the high-temperature calcination process, a condensation reaction occurs in the mixture, which is beneficial to the formation of silicon-aluminum-phosphorus composite oxides.

[0023] 5. The silicon-aluminum-phosphorus composite oxide prepared by the present invention can convert lithium chloride into Li3PO4 and Li x Al x Si1-x O 2-x The chlorine content in the product is less than 10000ppm, which can meet the needs of subsequent glass solidification and has significant progressive significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of the preparation method of the present invention;

[0025] Figure 2 This is a picture of the silicon-aluminum-phosphorus composite oxide product prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] A method for synthesizing a silicon-aluminum-phosphorus composite oxide, characterized in that it comprises the following steps:

[0029] Step 1: Heat and stir phosphoric acid, and add an aluminum source and water to form an aluminum phosphate suspension.

[0030] Among them, phosphoric acid shall comply with the requirements of GB / T 1282-2013, and the aluminum source is one or more of pseudo-boehmite, aluminum hydroxide, and activated alumina; the heating temperature is 20-100°C, which can ensure that the phosphorus source and the aluminum source are fully reacted and mixed, and ensure operational safety and energy economy; phosphoric acid and the aluminum source shall meet the molar stoichiometric ratio of Al:P (0.5-2): (0.5-3), so that there are enough Al and P to form chemical bonds; the stirring method can be magnetic stirring or mechanical stirring, which can ensure that the phosphorus source and the aluminum source are fully reacted and mixed; an appropriate amount of water can reduce the viscosity of the liquid, which is conducive to the full reaction and mixing of the phosphorus source and the aluminum source.

[0031] Step 2: Dissolve the silicon source to obtain a silicon source solution.

[0032] Wherein, the silicon source is one or more of silica sol and fumed silica.

[0033] Step 3: Mix the aluminum phosphate suspension and the silicon source solution, dry and calcine to obtain a silicon-aluminum-phosphorus composite oxide.

[0034] The mixed aluminum phosphate suspension and silicon source solution are dried to obtain a solid mixture, and the drying conditions are oven drying at 70-120°C for 24 hours; the calcination temperature is 500-800°C, and the calcination time is greater than 2 hours. During the high-temperature calcination process, the mixture undergoes a condensation reaction to generate a silicon-aluminum-phosphorus composite oxide.

[0035] The present invention also provides a silicon-aluminum-phosphorus composite oxide, which is a composite of SiO2, Al2O3 and P2O5.

[0036] The molar ratio of silicon, aluminum and phosphorus is Si:Al:P=1:0.5~2:0.5~3.

[0037] The present invention also provides an application of silicon-aluminum-phosphorus composite oxide in removing chlorine from metal chloride.

[0038] The steps include:

[0039] Step 1: Evenly mix the metal chloride and the silicon-aluminum-phosphorus composite oxide in a certain proportion.

[0040] Among them, the metal chloride is a chloride molten salt produced during the spent fuel reprocessing process, and can be one or a mixture of alkali metal chloride, alkaline earth metal chloride, actinide chloride and rare earth chloride; the ratio of metal chloride to silicon-aluminum-phosphorus composite oxide is a mass ratio of 1.0: (1.0~2.0).

[0041] Step 2: The mixture is heated to a certain temperature to cause a dechlorination reaction, and the chlorine element is converted into chlorine gas and leaves the mixture system. After the reaction is completed, it is cooled to room temperature to obtain a mixture without chlorine element.

[0042] Wherein, the temperature is 600-800°C.

[0043] The basic principle of dechlorination reaction is:

[0044] LiCl+SAP→Li3PO4+Li x Al x Si 1-x O 2-x +Cl2

[0045] The present invention can synthesize silicon-aluminum-phosphorus composite oxides and has the ability to efficiently remove chlorine from metal chlorides. Experimental results show that the silicon-aluminum-phosphorus composite oxides prepared by the present invention can convert lithium chloride into Li3PO4 and Li x Al x Si 1-x O 2-xThe chlorine content in the product is lower than 10000ppm, which can meet the needs of subsequent glass solidification and has significant progressive significance. On the other hand, the method adopted by the present invention greatly improves the safety and operability of the process, is easy to scale up, can realize large-scale production, has good application prospects, and is worthy of large-scale promotion and application.

[0046] Example 1

[0047] This embodiment provides a method for synthesizing a silicon-aluminum-phosphorus composite oxide, comprising the following specific steps:

[0048] S1: Add 115.29g phosphoric acid to a beaker, stir with a magnetic stirrer at a speed of 500rpm, and heat to 70°C; weigh 78g aluminum hydroxide, gradually add it to the phosphoric acid, add an appropriate amount of deionized water, and continue stirring to make the aluminum hydroxide evenly dispersed;

[0049] S2: Add 100g of deionized water to a beaker and stir with a magnetic stirrer at a speed of 500rpm; weigh 60g of fumed silica and gradually add it to the deionized water, and continue stirring to form a uniformly dispersed silica sol solution;

[0050] S3: adding the silica sol solution prepared in step S2 to step S1, and continuously stirring until it is evenly dispersed;

[0051] S4: placing the solution obtained in step S3 into an oven and drying it at 110° C. for 24 hours; then transferring it into a muffle furnace and calcining it at 600° C. for 3 hours to obtain a solid product of silicon-aluminum-phosphorus composite oxide.

[0052] The application of this embodiment is as follows:

[0053] S1: Mix 100g of LiCl and 150g of the silicon-aluminum-phosphorus composite oxide prepared in step S4, and grind them evenly;

[0054] S2: The mixture of step S5 is heated to 650° C. and reacted for 3 hours.

[0055] S3: After the reaction product of step S6 is cooled to room temperature, a mixture free of chlorine is obtained. Analysis results show that the chlorine content is 900 ppm.

[0056] Example 2

[0057] This embodiment provides a method for synthesizing a silicon-aluminum-phosphorus composite oxide, comprising the following specific steps:

[0058] S1: Add 144.12g of phosphoric acid into a beaker, stir with a magnetic force at a speed of 300rpm, and heat to 50°C; weigh 72.86g of pseudo-boehmite, gradually add it to the phosphoric acid, and add an appropriate amount of deionized water, and continue stirring to make the pseudo-boehmite evenly dispersed;

[0059] S2: Weigh 200 g of silica sol and add it to step S1, and continue stirring until it is evenly dispersed to obtain a mixed solution;

[0060] S3: placing the solution obtained in step S2 into an oven and drying it at 100° C. for 24 hours; then transferring it into a muffle furnace and calcining it at 700° C. for 2 hours to obtain a solid product of silicon-aluminum-phosphorus composite oxide.

[0061] The application of this embodiment is as follows:

[0062] S1: Mix 90g LiCl, 10g CsCl and 110g silicon-aluminum-phosphorus composite oxide prepared in step S3, and grind them evenly;

[0063] S2: The mixture of step S4 is heated to 700° C. and reacted for 3 hours.

[0064] S3: After the reaction product of step S5 is cooled to room temperature, a mixture free of chlorine is obtained. Analysis results show that the chlorine content is 2200 ppm.

[0065] Example 3

[0066] This embodiment provides a method for synthesizing a silicon-aluminum-phosphorus composite oxide, comprising the following specific steps:

[0067] S1: Add 172.94 g phosphoric acid into a beaker, stir with a magnetic stirrer at a speed of 400 rpm, and heat to 60°C; weigh 78 g aluminum hydroxide, gradually add it to the phosphoric acid, add an appropriate amount of deionized water, and continue stirring to make the aluminum hydroxide evenly dispersed;

[0068] S2: Weigh 200 g of silica sol and continue stirring to obtain a silica sol solution;

[0069] S3: adding the solution prepared in step S1 to the solution in step S2, and continuously stirring until the solution is evenly dispersed to obtain a mixed solution;

[0070] S4: placing the solution obtained in step S3 into an oven and drying it at 100° C. for 24 hours; then transferring it into a muffle furnace and calcining it at 550° C. for 4 hours to obtain a solid product of silicon-aluminum-phosphorus composite oxide.

[0071] The application of this embodiment is as follows:

[0072] S1: 90 g of LiCl, 10 g of CsCl and 130 g of the silicon-aluminum-phosphorus composite oxide prepared in step S4 are mixed and ground evenly;

[0073] S2: The mixture of step S5 is heated to 700° C. and reacted for 3 hours.

[0074] S3: After the reaction product of step S6 is cooled to room temperature, a mixture free of chlorine is obtained. Analysis results show that the chlorine content is 850 ppm.

[0075] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0076] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for synthesizing a silicon-aluminum-phosphorus composite oxide, characterized in that: The steps include: Step 1: Heat and stir phosphoric acid, and add an aluminum source and water to form an aluminum phosphate suspension; Step 2: dissolving the silicon source to obtain a silicon source solution; Step 3: Mix the aluminum phosphate suspension and the silicon source solution, dry and calcine to obtain a silicon-aluminum-phosphorus composite oxide.

2. The method for synthesizing a silicon-aluminum-phosphorus composite oxide according to claim 1, characterized in that: The aluminum source is one or more of pseudo-boehmite, aluminum hydroxide, and activated alumina.

3. The method for synthesizing a silicon-aluminum-phosphorus composite oxide according to claim 1, characterized in that: The silicon source is one or more of silica sol and fumed silica.

4. The method for synthesizing a silicon-aluminum-phosphorus composite oxide according to claim 1, characterized in that: In the step 1, the heating temperature is 20-100°C.

5. The method for synthesizing a silicon-aluminum-phosphorus composite oxide according to claim 1, characterized in that: In the step 3, the calcination temperature is 500° C. to 800° C., and the calcination time is greater than 2 hours.

6. A silicon-aluminum-phosphorus composite oxide prepared by the synthesis method of the silicon-aluminum-phosphorus composite oxide according to any one of claims 1 to 5, characterized in that: The silicon-aluminum-phosphorus composite oxide is a composite of SiO2, Al2O3 and P2O5.

7. The silicon-aluminum-phosphorus composite oxide according to claim 6, characterized in that: The molar ratio of silicon, aluminum and phosphorus is Si:Al:P=1:0.5~2:0.5~3.

8. Use of a silicon-aluminum-phosphorus composite oxide according to any one of claims 6 or 7 in removing chlorine from metal chloride.

Images