A method for recycling fluorinated aluminum silicon slag

Abstract

The application discloses a resource utilization method of fluorinated aluminum silicon slag. The resource utilization method comprises the following steps: adding the fluorinated aluminum silicon slag into an alkali solution to react, and then performing solid-liquid separation to obtain a solid and a liquid; the solid is recycled; the pH of the liquid is adjusted to 1.5-3.0 to obtain a fluorosilicate solution; ammonia water and a template agent are added into the fluorosilicate solution to obtain a silica sol; a fluorotitanate solution is prepared and added into the silica sol to obtain a precursor solution; after static crystallization of the precursor solution, solid-liquid separation is performed; the obtained solid is stirred in water overnight, and then suction filtration is performed to obtain a liquid phase and a solid phase; after water removal, the liquid phase is used to prepare ammonium fluoride; the solid phase is dried to obtain a precursor; and the precursor is calcined to obtain TS-1 molecular sieve. The application uses the fluorinated aluminum silicon slag as a silicon source, uses various different fluorotitanate as a titanium source, and combines a template agent to synthesize the TS-1 molecular sieve, and meanwhile, the fluorinated aluminum and the ammonium fluoride can be recycled, thereby providing a new idea for processing of industrial fluorosilicic acid by-products.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of comprehensive utilization of resources, and particularly relates to a method for recycling aluminum fluoride-containing silicon slag. BACKGROUND

[0002] Molecular sieve is a kind of inorganic porous material with three-dimensional four-connected structure, which is formed by sharing oxygen vertices of adjacent TO4 tetrahedrons, and usually takes Si, Al or P atom as T atom of framework. Silicate molecular sieve is the most typical molecular sieve, and its chemical general formula is A x / n (SiO2)(AlO2) x ·mH2O (A: cation, n-valence). According to the size of the pore channel, the International Molecular Sieve Association divides molecular sieves into microporous, mesoporous and macroporous molecular sieves. The microporous molecular sieve has a pore channel less than 2 nm, the mesoporous molecular sieve has a pore channel between 2 nm and 50 nm, and the macroporous molecular sieve has a pore channel greater than 50 nm. The molecular sieve is named according to the pore channel structure. So far, 255 kinds of molecular sieve structures have been collected, including 246 kinds of ordered structures and 9 kinds of disordered structures. Each structure is represented by three capital letters, which are generally the name of a typical material of the structure, for example, Chabazite-CHA. An important milestone in the development of molecular sieves is that the ZSM-5 molecular sieve with high silicon and aluminum was synthesized by the Mobil Company in the United States in 1972. The ZSM-5 molecular sieve is a typical silicate molecular sieve with MFI structure. The molecular sieve with MFI structure contains two kinds of ten-membered ring pore channel structures, which are Z-shaped ten-membered ring pore channel parallel to the X axis and straight ten-membered ring pore channel parallel to the Z axis. The pore diameter of the pore channel parallel to the X axis is 0.55*0.51 nm, and the pore diameter of the pore channel parallel to the Z axis is 0.56*0.53 nm. The pore diameter of the ten-membered ring pore channel is in the microporous range, and the structure is stable and has high acidity, so the molecular sieve with MFI structure is widely used in industrial catalytic reactions. TS-1 microporous molecular sieve is also a molecular sieve with MFI structure, which is different from the ZSM-5 molecular sieve in that the crystal structure of the TS-1 molecular sieve is formed by replacing the aluminum atom in the ZSM-5 molecular sieve with a Ti atom, so that the molecular sieve framework contains four-coordinated Ti. Ti(IV) has shape-selective catalytic function and plays an important role in organic shape-selective catalysis with hydrogen peroxide as oxidant, because Ti(IV) will not cause deep oxidation of the synthesized compound, and has good stability in this type of reaction. In addition, Ti(IV) can effectively promote the oxidation of organic matter in the reaction process and has good catalytic effect. Therefore, Ti(IV) is a very effective catalyst and can be used in various organic oxidation reactions.

[0003] The conventional method for synthesizing TS-1 molecular sieve at present is to use tetraethyl orthosilicate as a silicon source, tetrabutyl titanate as a titanium source and tetrapropyl ammonium hydroxide as a template agent. Both the titanium source and the silicon source are organic ester compounds, which are much more expensive than inorganic compounds, and the template agent tetrapropyl ammonium hydroxide is also more expensive than tetrapropyl ammonium bromide. It is of great value to develop the use of inorganic silicon source and titanium source to synthesize TS-1 molecular sieve. The patent with publication number CN114455602A discloses a method for synthesizing TS-1 by using natural diatomite. In the method, the natural diatomite is calcined and acid-treated to obtain modified diatomite, and then the modified diatomite is used as a silicon source, tetrabutyl titanate is used as a titanium source and tetrapropyl ammonium hydroxide is used as a template agent to synthesize TS-1 molecular sieve. Although the method uses diatomite as a silicon source instead of organic silicon source, the titanium source used is still tetrabutyl titanate. The patent with publication number CN111908483A discloses a method for synthesizing TS-1 molecular sieve by using natural attapulgite (a cheap layered silicate material) as a silicon source, tetrabutyl titanate as a titanium source and tetrapropyl ammonium hydroxide as a template agent. The above patents all consider replacing organic silicon ester from the perspective of the silicon source, but there is no good solution to obtain cheap titanium source. Hubei is a large province of phosphorus resources, and a lot of industrial fluosilicic acid will be by-produced along with the production of phosphate fertilizer. At present, the industrial fluosilicic acid is used to prepare white carbon black, sodium fluoride, aluminum fluoride and the like. In the production of aluminum fluoride, part of the aluminum fluoride will be separated out along with the silicon dioxide in the separation process, forming a kind of aluminum fluoride-containing silicon residue which is rich in fluorine and silicon resources. The patent with publication number CN113479899A discloses that the industrial fluosilicic acid is used as a silicon source to synthesize SAPO series molecular sieve. It can be seen that the aluminum fluoride-containing silicon residue can be used as a silicon source to replace the organic silicon ester in the process of synthesizing molecular sieve. Moreover, the aluminum fluoride-containing silicon residue contains a large amount of fluorine resources, which are generally used to produce some cheap fluorinated salts, and the development and utilization of the fluorine resources are not high. If the aluminum fluoride-containing silicon residue is well utilized, the green treatment of the by-products of wet-process phosphoric acid can be realized. SUMMARY

[0004] In view of the deficiencies in the prior art, the purpose of the present application is to provide a resource utilization method of aluminum fluoride-containing silicon residue.

[0005] The purpose of the present application is achieved by the following technical solutions.

[0006] A resource utilization method of aluminum fluoride-containing silicon residue, comprising the following steps:

[0007] (1) The aluminum fluoride-containing silicon residue is dissolved in an alkali solution for a reaction, and then solid-liquid separation is performed, and the separated solid is dried and recovered (the component is aluminum fluoride); the pH of the separated liquid is adjusted to 1.5-3.0 by using hydrofluoric acid, to obtain a fluosilicate solution after the silicon residue is dissolved by the hydrofluoric acid;

[0008] (2) stirring the fluorosilicate solution after the silicon slag is dissolved by hydrofluoric acid, adding ammonia water, and then adding a template agent to obtain a silica sol, which is ready for use;

[0009] (3) preparing a fluorotitanate solution, adding it to the system of step (2) and stirring to obtain a precursor solution, statically crystallizing the precursor solution at 150-230°C, performing solid-liquid separation after the crystallization is completed, and then stirring the separated solid in water overnight, followed by suction filtration to obtain a liquid phase and a solid phase, removing water from the liquid phase to obtain ammonium fluoride, drying the solid phase to obtain a precursor, and directly calcining or condensing and refluxing the precursor, followed by drying and calcining to obtain TS-1 molecular sieve, thereby completing the resource treatment.

[0010] Preferably, in step (1), the source of the silicon slag containing aluminum fluoride is that part of the aluminum fluoride is separated from the silicon dioxide during the separation in the process of producing aluminum fluoride from industrial fluorosilicic acid.

[0011] Preferably, in step (1), the silicon slag containing aluminum fluoride is dissolved in the lye for 12 h.

[0012] Preferably, in step (1), the concentration of the lye is 3-5 mol / L.

[0013] Preferably, in step (1), the lye is at least one of sodium hydroxide and potassium hydroxide.

[0014] Preferably, in step (1), the amount of the silicon slag containing aluminum fluoride added to the lye is 0.1-0.5 g / mL.

[0015] Preferably, in step (1), the concentration of the hydrofluoric acid is 40 wt%.

[0016] Preferably, in step (2), the concentration of the ammonia water is 25-28 wt%.

[0017] Preferably, in step (2), the volume ratio of the fluorosilicate solution after the silicon slag is dissolved by hydrofluoric acid to the ammonia water is 2:1-4:1.

[0018] Preferably, in step (2), the template agent is one of tetrapropylammonium bromide, tetrapropylammonium hydroxide, and tetraethylammonium hydroxide.

[0019] Preferably, in step (3), the fluorotitanate solution is prepared in one of the following ways:

[0020] Way one: using titanium dioxide as the titanium source

[0021] The titanium dioxide is added to hydrofluoric acid, stirred to completely dissolve, and then hydrogen peroxide and ammonia water are added in sequence to prepare the fluorotitanate solution.

[0022] The ratio of the amount of titanium dioxide to hydrofluoric acid is 0.03-0.10 g / mL.

[0023] The concentration of the hydrofluoric acid is 40 wt%.

[0024] Preferably, the ratio of the amount of titanium dioxide to hydrogen peroxide is 0.04-0.12 g / mL, and the concentration of the hydrogen peroxide is 30-32 wt%.

[0025] Preferably, the ratio of the amount of titanium dioxide to ammonia is 0.03-0.08 g / mL, and the concentration of the ammonia is 25-28 wt%.

[0026] When titanium dioxide is used as the titanium source, the titanium dioxide is dissolved into tetravalent titanium ions under the action of the hydrofluoric acid. The tetravalent titanium, fluoride ions, peroxide ions and ammonium ions form stable complexes in the solution, which exist stably in water, so that the titanium source is more likely to form tetracoordinated titanium when added into the silica sol.

[0027] Method two: using titanium trichloride as the titanium source

[0028] The titanium trichloride solution is stirred in air, and then the hydrofluoric acid is added to prepare a fluorotitanate solution.

[0029] Preferably, the concentration of the titanium trichloride solution is 15-20 wt%, the volume ratio of the hydrofluoric acid to the titanium trichloride solution is 1:1-1:3, and the concentration of the hydrofluoric acid is 40 wt%.

[0030] When titanium trichloride is used as the titanium source, the oxygen in the air is easy to oxidize the trivalent titanium in the solution into tetravalent titanium. A small amount of hydrofluoric acid is added to make the oxidized tetravalent titanium exist more stably in the solution. Fluorine and chlorine are elements in the same main group, and have similar chemical properties. They exist in the form of titanium chlorofluoride in the solution, and are added into the silica sol to synthesize titanium silicalite molecular sieves.

[0031] Method three: using sodium fluorotitanate as the titanium source

[0032] The sodium fluorotitanate solid is added to water, and stirred to completely dissolve, to prepare a fluorotitanate solution.

[0033] When sodium fluorotitanate is used as the titanium source, the sodium fluorotitanate solid is dissolved in water to dissociate fluorotitanate ions, which are added into the silica sol to synthesize titanium-containing molecular sieves.

[0034] Preferably, the ratio of the amount of sodium fluorotitanate to water is 0.1-0.3 g / mL.

[0035] Preferably, when titanium dioxide is used as the titanium source, the molar ratio of silicon in the fluorosilicate solution after the titanium, silicon residue in the prepared fluorotitanate solution is dissolved by the hydrofluoric acid to the template agent is 0.05-0.2:1:0.1-0.3.

[0036] Preferably, when titanium trichloride is used as the titanium source, the molar ratio of titanium in the prepared fluorotitanate solution, silicon in the fluorosilicate solution after the silicon residue in the fluorotitanate solution is dissolved by hydrofluoric acid, and the template agent is 0.02-0.1:1:0.1-0.2.

[0037] Preferably, when sodium fluorotitanate is used as the titanium source, the molar ratio of titanium in the prepared fluorotitanate solution, silicon in the fluorosilicate solution after the silicon residue in the fluorotitanate solution is dissolved by hydrofluoric acid, and the template agent is 0.02-0.08:1:0.1-0.2.

[0038] Preferably, in step (3), the static crystallization time is 1-8 days.

[0039] Preferably, in step (3), the drying temperature of the solid phase is 50-80℃, and the drying time is 12-24h.

[0040] Preferably, in step (3), the direct calcination method of the precursor is calcination at 500-650℃ for 4-6h.

[0041] Preferably, in step (3), the method of drying after condensation reflux is as follows: the precursor is added to an acid solution, dried after condensation reflux at 40-80℃ for 2-6h, and calcined at 550℃ for 4-6h.

[0042] Preferably, the concentration of the acid solution is 1-5mol / L.

[0043] Preferably, the acid solution is at least one of nitric acid solution, sulfuric acid solution, hydrochloric acid solution, and acetic acid solution.

[0044] The reaction mechanism involved in the present application is as follows:

[0045] The application provides a method for synthesizing microporous molecular sieve TS-1 and co-producing fluorides by using industrial by-product fluorosilicic acid containing aluminum silicon fluoride slag and various different fluorotitanate. The aluminum silicon fluoride slag contains a large amount of silicon and fluorine elements, and the silicon in the aluminum silicon fluoride slag is used as a silicon source to replace the high-cost organic silicon source, liquid-phase silicon dioxide or gas-phase silicon dioxide. The TS-1 molecular sieve is synthesized by using various different fluorotitanate as a titanium source and combining a template agent. In the process of synthesizing the TS-1 molecular sieve, different titanium sources are added with different reagents to have similar properties to synthesize the molecular sieve. A large amount of fluorine ions are contained in the reaction system, and the fluorine ions can play a good crystal promotion effect in the process of synthesizing the molecular sieve with the MFI structure, so that the synthesis time of the molecular sieve is shortened. When sodium hydroxide is used to dissolve the aluminum silicon fluoride slag, the silicon dioxide in the slag is completely dissolved, and the pure aluminum fluoride solid is obtained after filtration. After the reaction is completed, the fluorine is precipitated together with the ammonium ion to crystallize the molecular sieve, the fluorides are enriched in water by using the water washing and stirring method, and the fluorine salt is obtained by reduced pressure distillation. The technology realizes the green treatment of the aluminum silicon fluoride slag, the silicon aluminum resources are comprehensively utilized, and a new idea is provided for synthesizing the TS-1 molecular sieve.

[0046] Compared with the prior art, the application has the following beneficial effects:

[0047] (1) The TS-1 molecular sieve with high added value is prepared by using the aluminum silicon fluoride slag as the raw material, so that the added value of the industrial by-product fluorosilicic acid is improved, the pollution to the environment is reduced, and a brand-new idea is provided for the green treatment of the by-product of the industrial fluorosilicic acid.

[0048] (2) In the prior art, the silicon source and the titanium source are mainly organic ester compounds, and the template agent is mainly tetrapropylammonium hydroxide, so that the cost is high and the time is long. In the application, the aluminum silicon fluoride slag is used as the silicon source, the fluorotitanate is used as the titanium source, the tetrapropylammonium bromide is used as the template agent, and the fluorine element in the fluorosilicic acid is used as the crystal promoter, so that the prepared molecular sieve has excellent quality and good MFI topological structure. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 The XRD graph of the aluminum silicon fluoride slag raw material.

[0050] Figure 2 The XRD graph of the aluminum silicon fluoride slag after being dissolved by alkali.

[0051] Figure 3 The XRD graph of the TS-1 molecular sieve prepared in the comparative example 1.

[0052] Figure 4 The XRD graph of the TS-1 molecular sieve prepared in the examples 1, 5 and 9.

[0053] Figure 5Nitrogen adsorption-desorption data plot of TS-1 molecular sieve prepared for Comparative Example 1, Example 1, 5 and 9.

[0054] Figure 6 Scanning electron microscope image of one point of TS-1 molecular sieve prepared for Example 1, wherein the scale in the figure = 10 μm.

[0055] Figure 7 Scanning electron microscope image of another point of TS-1 molecular sieve prepared for Example 1, wherein the scale in the figure = 10 μm. DETAILED DESCRIPTION

[0056] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0057] The aluminum fluoride-containing silicon slag in the examples and comparative examples was subjected to element composition analysis by scanning electron microscope-energy dispersive spectrometer (SEM-EDS), and the test results are shown in Table 1. 1 g of the aluminum fluoride-containing silicon slag was placed in a muffle furnace, calcined at 300°C for 3 h to remove free water and crystal water in the silicon slag, and weighed as 0.72 g after cooling. Based on the above, the composition of the aluminum fluoride-containing silicon slag is: 48% SiO2, 20.72% AlF3, 2.46% NaF, 28% H2O and 0.82% impurities.

[0058] Table 1 List of element composition of aluminum fluoride-containing silicon slag

[0059]

[0060] Comparative Example 1

[0061] Tetrabutyl titanate is widely used in the synthesis of titanium-containing molecular sieves due to its excellent performance in the synthesis of titanium-containing molecular sieves. In this example, TS-1 molecular sieve was synthesized using aluminum fluoride-containing silicon slag as a silicon source and tetrabutyl titanate as a titanium source, and the synthesis steps were as follows:

[0062] (1) 7.3 g of aluminum fluoride-containing silicon slag was added to 65 mL of a sodium hydroxide solution with a concentration of 3 mol / L and dissolved, and after overnight reaction, the solid-liquid was separated by suction filtration, and the obtained solid was dried in an oven. After drying, aluminum fluoride was recovered. Concentrated hydrofluoric acid with a concentration of 40% was added to the obtained liquid, and the hydrofluoric acid was adjusted to a pH of 2.1 to obtain a fluorosilicate solution.

[0063] (2) The fluosilicate solution obtained in step (1) was added to 15 mL of ammonia water with a concentration of 30 wt% under stirring, and the system became gelatinous. Then, 3.045 g of tetrapropylammonium bromide (TPABr) was slowly added, and the pH of the system was measured to be 12.3 under stirring, obtaining a silica sol.

[0064] (3) In a beaker containing 0.648 g of isopropyl alcohol (IPA), 0.164 g of tetrabutyl titanate was added to dissolve the tetrabutyl titanate in isopropyl alcohol, obtaining a tetrabutyl titanate isopropyl alcohol solution.

[0065] (4) The tetrabutyl titanate isopropyl alcohol solution was added to the silica sol obtained in step (2), and the system was stirred to be uniformly mixed, and the pH of the system was measured to be 9.7, obtaining a precursor liquid.

[0066] (5) The precursor liquid was added to a polytetrafluoroethylene liner, and static crystallization was carried out at 190℃ for 6 days. After the crystallization was completed, the solid-liquid was separated by filtration. The obtained solid was washed with deionized water until neutral, and dried in an oven at 80℃ for 18 hours to obtain a precursor. The precursor was placed in a muffle furnace, and calcination was carried out at 600℃ for 4 hours to obtain TS-1 molecular sieve, which was named A-TS-1-r.

[0067] Comparative Example 2

[0068] On the basis of Comparative Example 1, the precursor obtained in step (4) was added to an acid solution, and reflux was carried out at 75℃ for 6 h. The acid was nitric acid, and the concentration of the acid solution was 2 mol / L. After the reflux was completed, washing and drying were carried out, and calcination was carried out at 550℃ for 4 h to obtain TS-1 molecular sieve, which was named A-TS-1-a. The other steps were the same as those in Comparative Example 1.

[0069] Example 1

[0070] A resource utilization method of aluminum fluoride silicon slag, the steps are as follows:

[0071] (1) 7.3 g of aluminum fluoride silicon slag was added to 65 mL of sodium hydroxide solution with a concentration of 3 mol / L and dissolved for 12 h. After the reaction was completed, the solid-liquid was separated by filtration, and the obtained solid was dried in an oven. After drying, the aluminum fluoride solid was recovered. The XRD pattern of the sample after the dissolution of the aluminum fluoride silicon slag in the alkali is shown in FIG. 1. In the obtained liquid, hydrofluoric acid with a concentration of 40% was added to adjust the pH of the liquid to 2.1, obtaining a fluosilicate solution. Figure 2

[0072] (2) The fluosilicate solution obtained in step (1) was added to 15 mL of ammonia water with a concentration of 28 wt% under stirring, and the system became gelatinous. Then, 2.895 g of tetrapropylammonium bromide (TPABr) was slowly added, and the pH of the system was measured to be 12.2 under stirring, obtaining a silica sol.

[0073] ​(3) 10 mL of 40 wt% hydrofluoric acid was added into a plastic beaker, 0.85 g of titanium dioxide was added, and the solid was stirred to completely dissolve. After the solid was completely dissolved, 8 mL of 30 wt% hydrogen peroxide and 12 mL of 25 wt% ammonia were added in sequence to obtain a fluorotitanate solution, which was used for later use.

[0074] The molar ratio of titanium in the fluorotitanate solution of step (3), silicon in the fluorosilicate solution of step (1) and tetrapropylammonium bromide was 0.182:1:0.186.

[0075] (4) The solution obtained in step (3) was added to the silica sol of step (2), and the system was stirred to be uniform. The pH of the system was measured to be 8.3, and a precursor solution was obtained.

[0076] (5) The precursor solution was added into a polytetrafluoroethylene liner and was put into a reactor. The system was statically crystallized at 175°C for 4 days. After the crystallization was completed, the solid-liquid was separated by filtration. The separated solid was stirred in water overnight, and then was suction filtered. The solid separated again was placed in an oven and was dried at 60°C for 24 hours to obtain a precursor. The precursor was placed in a muffle furnace and was calcined at 650°C for 5 hours to obtain TS-1 molecular sieve, which was named as B-TS-1-1-r. The liquid separated again was placed in a rotary evaporator and was vacuum rotary evaporated at 80°C. After the water was completely evaporated, ammonium fluoride solid was obtained.

[0077] Example 2

[0078] On the basis of Example 1, only the following conditions were changed, and the other steps were the same as those in Example 1.

[0079] The precursor obtained in step (4) was added into an acid solution, and was refluxed at 75°C for 6 hours. The acid was nitric acid, and the concentration of the acid solution was 2 mol / L. After the reflux was completed, the precursor was washed and dried, and was calcined at 550°C for 4 hours to obtain TS-1 molecular sieve, which was named as B-TS-1-1-a.

[0080] Example 3

[0081] On the basis of Example 1, only the following conditions were changed, and the other steps were the same as those in Example 1.

[0082] The mass of titanium dioxide in step (3) was 0.43 g.

[0083] The molar ratio of titanium in the fluorotitanate solution of step (3), silicon in the fluorosilicate solution of step (1) and tetrapropylammonium bromide was 0.092:1:0.186. The obtained molecular sieve was named as B-TS-1-2-r.

[0084] Example 4

[0085] On the basis of example 3, only the following conditions are changed, other steps are the same as example 3:

[0086] The precursor is added to an acid solution, the acid is nitric acid, the concentration of the acid solution is 2 mol / L, and the reflux is carried out at 75℃ for 6h. After the reflux is completed, it is washed and dried, and is calcined at 550℃ for 4h to obtain TS-1 molecular sieve, which is named as B-TS-1-2-a.

[0087] Example 5

[0088] A resource utilization method of aluminum fluoride silicon slag, the steps are as follows:

[0089] (1) 7.3g of aluminum fluoride silicon slag is added to 65mL of sodium hydroxide solution with a concentration of 3mol / L and dissolved for 12h. After the reaction is completed, the solid-liquid separation is carried out by suction filtration. The obtained solid is dried in an oven. After drying, the recovered aluminum fluoride solid is obtained. In the obtained liquid, 40% hydrofluoric acid is added to adjust the pH to 2.1 to obtain a fluosilicate solution.

[0090] (2) The fluosilicate solution obtained in step (1) is added to 15mL of 28wt% ammonia water under stirring. The system becomes gelatinous. 2.594g of tetrapropylammonium bromide (TPABr) is slowly added. The pH of the system is measured to be 12.2 to obtain a silica sol.

[0091] (3) 10mL of water is added to a beaker. 1.584g of 20wt% titanium trichloride solution is weighed and added to the beaker using a rubber bulb dropper. After stirring in the air for a period of time, 1mL of 40wt% hydrofluoric acid is added to the beaker to obtain a fluorotitanate solution for standby.

[0092] The molar ratio of titanium in the fluorotitanate solution of step (3), silicon in the fluosilicate solution of step (1) and tetrapropylammonium bromide is 0.035:1:0.167.

[0093] (4) The solution obtained in step (3) is added to the silica sol of step (2). The system is stirred to be uniform. The pH of the system is measured to be 9.8 to obtain a precursor solution.

[0094] (5) The precursor solution is added to a polytetrafluoroethylene liner and put into a reactor. The static crystallization is carried out at 175℃ for 4 days. After the crystallization is completed, the solid-liquid separation is carried out by filtration. The separated solid is stirred in water overnight. After stirring overnight, suction filtration is carried out. The separated solid is placed in an oven and dried at 60℃ for 24h to obtain a precursor. The precursor is placed in a muffle furnace and calcined at 650℃ for 5h to obtain TS-1 molecular sieve, which is named as C-TS-1-1-r. The liquid separated again is placed in a rotary evaporator and vacuum rotary evaporation is carried out at 80℃. After the water is completely evaporated, ammonium fluoride solid is obtained.

[0095] Example 6

[0096] On the basis of Example 5, only the following conditions are changed, and other steps are the same as in Example 5:

[0097] The precursor obtained in step (5) is added to an acid solution, and refluxed at 75°C for 6h, the acid is nitric acid, and the concentration of the acid solution is 2mol / L. After reflux, washing and drying, TS-1 molecular sieve is obtained by calcination at 550°C for 4h, and is named as C-TS-1-1-a.

[0098] Example 7

[0099] On the basis of Example 5, only the following conditions are changed, and other steps are the same as in Example 5:

[0100] The mass of the titanium trichloride solution in step (2) is 0.792g;

[0101] The molar ratio of titanium in the fluorotitanate solution prepared in step (3), silicon in the fluorosilicate solution in step (1) and tetrapropylammonium bromide is 0.018:1:0.167.

[0102] The precursor is calcined at 650°C for 5h in a muffle furnace to obtain TS-1 molecular sieve, which is named as C-TS-1-2-r.

[0103] Example 8

[0104] On the basis of Example 7, only the following conditions are changed, and other steps are the same as in Example 7:

[0105] The precursor obtained in step (5) is added to an acid solution, and refluxed at 75°C for 6h, the acid is nitric acid, and the concentration of the acid solution is 2mol / L. After reflux, washing and drying, TS-1 molecular sieve is obtained by calcination at 550°C for 4h, and is named as C-TS-1-2-a.

[0106] Example 9

[0107] A resource utilization method of aluminum fluoride silicon slag, the steps are as follows:

[0108] (1) 7.3g of aluminum fluoride silicon slag is weighed and added to 65mL of sodium hydroxide solution with a concentration of 3mol / L and dissolved for 12h. After the reaction is completed, the solid-liquid separation is carried out by suction filtration, and the obtained solid is dried in an oven. After drying, the aluminum fluoride solid is recovered, and concentrated hydrofluoric acid with a concentration of 40wt% is added to the obtained liquid to adjust the liquid to pH 2.1 to obtain a fluorosilicate solution.

[0109] (2) The fluosilicate solution obtained in step (1) was added to 15 mL of ammonia water with a concentration of 28 wt% under stirring. The system became gelatinous. Then, 2.594 g of tetrapropylammonium bromide (TPABr) was slowly added. The pH of the system was measured to be 12.2. A silica sol was obtained.

[0110] (3) 5 mL of water was added to a beaker. Then, 0.962 g of sodium fluotitanate solid was added and stirred until the solid was completely dissolved, obtaining a fluotitanate solution, which was used for the next step.

[0111] The molar ratio of titanium in the fluotitanate solution of step (3), silicon in the fluosilicate solution of step (1) and tetrapropylammonium bromide was 0.079:1:0.167.

[0112] (4) The solution obtained in step (3) was added to the silica sol of step (2) and stirred until the system was uniform. The pH of the system was measured to be 10.3. A precursor solution was obtained.

[0113] (5) The precursor solution was added to a Teflon liner and put into a reactor. The system was crystallized at 175 ℃ for 4 days. After the crystallization, the solid-liquid was separated by filtration. The separated solid was stirred in water overnight. After stirring overnight, the solid was separated by suction filtration. The separated solid was dried in an oven at 60 ℃ for 24 hours to obtain a precursor. The precursor was calcined in a muffle furnace at 650 ℃ for 5 hours to obtain TS-1 molecular sieve, which was named as D-TS-1-1-r. The liquid was placed in a rotary evaporator and vacuum rotary evaporation was performed at 80 ℃ until the water was completely evaporated, obtaining ammonium fluoride solid.

[0114] Example 10

[0115] On the basis of Example 9, only the following conditions were changed. The other steps were the same as those in Example 9.

[0116] The precursor obtained in step (4) was added to an acid solution. The acid was nitric acid. The concentration of the acid solution was 2 mol / L. The system was refluxed at 75 ℃ for 6 hours. After the reflux, the system was washed and dried. The TS-1 molecular sieve was obtained by calcination at 550 ℃ for 4 hours. The TS-1 molecular sieve was named as D-TS-1-1-a.

[0117] Example 11

[0118] On the basis of Example 9, only the following conditions were changed. The other steps were the same as those in Example 9.

[0119] The mass of sodium fluotitanate solid in step (2) was 0.480 g.

[0120] The molar ratio of titanium in the fluotitanate solution of step (3), silicon in the fluosilicate solution of step (1) and tetrapropylammonium bromide was 0.039:1:0.167.

[0121] The precursor was placed in a muffle furnace at 650°C for 5 hours to obtain TS-1 molecular sieve, named D-TS-1-2-r.

[0122] Example 12

[0123] On the basis of Example 11, only the following conditions were changed, and the other steps were the same as in Example 9:

[0124] The precursor obtained in step (4) was added to an acid solution, and refluxed at 75°C for 6h, the acid was nitric acid, and the concentration of the acid solution was 2 mol / L. After refluxing, washing and drying, TS-1 molecular sieve was obtained by calcination at 550°C for 4h, named D-TS-1-2-a.

[0125] The TS-1 molecular sieves prepared by different methods were subjected to 1-hexene oxidation reaction, and the catalytic activities of the prepared molecular sieves were compared. 0.1 g of the molecular sieve was taken in a three-necked flask, 10 mmol of 1-hexene was added to the three-necked flask, 10 mL of acetonitrile was added to the three-necked flask after addition was completed, 10 mmol of hydrogen peroxide was added at a constant speed by using a peristaltic pump, and 60°C condensation reflux was carried out for 4h. In the reaction, 1-hexene was the raw material, acetonitrile was the solvent, and hydrogen peroxide was the oxidizing agent. After the reaction was completed, the product 1,2-epoxyhexane was obtained. The product was analyzed and detected by using GC-MS. The catalytic results of different molecular sieves are shown in Table 2.

[0126] Table 2: Catalytic performance table of different TS-1 molecular sieves

[0127]

[0128] X: conversion rate, S: selectivity

[0129] From the above comparative examples and examples, we found that compared with the microporous molecular sieve TS-1 obtained by directly placing the precursor in the muffle furnace for calcination, the microporous molecular sieve TS-1 obtained by acid treatment of the precursor before placing it in the muffle furnace for calcination has better effect on the catalytic oxidation of 1-hexene, and the catalytic performance is improved. Compared with the commonly used organic titanium source (tetrabutyl titanate), the catalytic performance of the molecular sieve synthesized using fluorotitanate is not much different, indicating that the TS-1 molecular sieve synthesized using fluorine-containing aluminum silicon slag has better quality.

[0130] Figure 1 The XRD pattern of the fluorine-containing aluminum silicon slag raw material is shown in the figure. It can be seen from the figure that there is an amorphous envelope peak between 15° and 30°, which is the characteristic peak of amorphous silicon dioxide. By comparing the standard card, it can be found that the characteristic diffraction peaks of the slag are consistent with the characteristic diffraction peaks of two different aluminum fluorides, which indicates that the main components of the slag are silicon dioxide, aluminum fluoride and water.

[0131] Figure 2 XRD pattern of the fluorinated aluminosilicate slag after being dissolved by alkali solution, comparison Figure 1 It can be found that the main change is that the amorphous peak disappears, which indicates that the alkali solution completely dissolves the silicon dioxide in the aluminum fluoride, and the remaining is pure aluminum fluoride solid.

[0132] Figure 3 XRD pattern of the TS-1 molecular sieve prepared in Comparative Example 1, from Figure 3 It can be seen that the sample has obvious characteristic diffraction peaks at 2θ of 7.9°, 8.8°, 23.1°, 23.9° and 24.4°, which are the characteristic diffraction peaks of MFI structure, indicating that the TS-1 molecular sieve with MFI structure can be prepared in Comparative Example 1.

[0133] Figure 4 XRD patterns of the TS-1 molecular sieves prepared in Examples 1, 5 and 9, from the figure it can be seen that the samples prepared by different methods have obvious characteristic diffraction peaks at 2θ of 7.9°, 8.8°, 23.1°, 23.9° and 24.4°, which are the characteristic diffraction peaks of MFI structure, indicating that the TS-1 molecular sieves with good MFI structure can be prepared by using different methods.

[0134] Figure 5 The TS-1 molecular sieves prepared in Comparative Example 1, Examples 1, 5 and 9 were dried at 373K for 2h, and then pretreated by high-purity nitrogen (99.99%) at 473K for 5h, and nitrogen adsorption was carried out on liquid nitrogen at 77K, and the nitrogen adsorption-desorption data curve was obtained, from Figure 5 It can be seen that the nitrogen adsorption-desorption curves of the samples prepared by different methods present a typical type I isotherm, which indicates that the molecular sieves prepared by different methods are typical microporous structures.

[0135] Figure 6~Figure 7 The scanning electron microscope image of the TS-1 molecular sieve prepared in Example 1 at different points, it can be seen that the TS-1 molecular sieve prepared by this method presents a regular hexagonal prism shape, and appears relatively long and thin along the y axis, which is closely related to the existence of more fluoride ions in the synthesis process, and the fluoride ions promote the formation of the molecular sieve and grow along the y axis.

[0136] The specific embodiments of the application described above do not constitute a limitation on the scope of protection of the application. Any various other corresponding changes and modifications made according to the technical concept of the application should be included in the protection scope of the claims of the application.

Claims

1. A method of resource recovery of a fluoroaluminosilicate slag, characterized in that, It comprises the following steps: (1) adding the fluorinated aluminum silicon slag into the alkali solution to react, and then separating the solid and liquid to obtain the solid and the liquid, recycling the solid, adjusting the pH of the liquid to 1.5-3.0 to obtain a fluosilicate solution; (2) adding ammonia and a template agent into the fluosilicate solution to obtain a silica sol; (3) preparing a fluotitanate solution, adding it into the silica sol to obtain a precursor solution, and then separating the solid and liquid after static crystallization, and then stirring the obtained solid in water overnight, and then filtering to obtain the liquid phase and the solid phase, and then removing water from the liquid phase to obtain ammonium fluoride, and then drying the solid phase to obtain the precursor, and then directly calcining the precursor to obtain TS-1 molecular sieve, and then completing the resource utilization; The fluotitanate solution in step (3) is prepared by one of the following methods: Method one: taking titanium dioxide as the titanium source adding titanium dioxide into hydrofluoric acid, stirring to completely dissolve it, and then adding hydrogen peroxide and ammonia in sequence to prepare the fluotitanate solution; the dosage ratio of the titanium dioxide to the hydrofluoric acid is 0.03-0.10 g / mL; the concentration of the hydrofluoric acid is 40 wt%; the dosage ratio of the titanium dioxide to the hydrogen peroxide is 0.04-0.12 g / mL, and the concentration of the hydrogen peroxide is 30-32 wt%; the dosage ratio of the titanium dioxide to the ammonia is 0.03-0.08 g / mL, and the concentration of the ammonia is 25-28 wt%; Method two: taking titanium trichloride as the titanium source stirring the titanium trichloride solution in air, and then adding hydrofluoric acid to prepare the fluotitanate solution; the concentration of the titanium trichloride solution is 15-20 wt%, the volume ratio of the hydrofluoric acid to the titanium trichloride solution is 1:1-1:3, and the concentration of the hydrofluoric acid is 40 wt%; Method three: taking sodium fluotitanate as the titanium source adding sodium fluotitanate solid into water, and stirring to completely dissolve it to prepare the fluotitanate solution; the dosage ratio of the sodium fluotitanate to water is 0.1-0.3 g / mL.

2. The method of reclaiming fluoroaluminosilicate slag according to claim 1, characterized by, The source of the fluorinated aluminum silicon slag in step (1) is the silicon slag containing aluminum fluoride formed by separating part of the aluminum fluoride from the silicon dioxide in the process of producing aluminum fluoride from industrial fluosilicic acid; The alkali solution in step (1) is at least one of sodium hydroxide and potassium hydroxide.

3. The method of reclaiming fluoroaluminosilicate slag according to claim 2, characterized in that, The concentration of the alkali solution in step (1) is 3-5 mol / L; The addition amount of the fluorinated aluminum silicon slag in the alkali solution in step (1) is 0.1-0.5 g / mL.

4. The method of reclaiming fluoroaluminosilicate slag according to claim 1, characterized in that, The reaction time of the fluorinated aluminum silicon slag in the alkali solution in step (1) is 12 h; The pH of the liquid is adjusted to 1.5-3.0 by using 40 wt% hydrofluoric acid in step (1).

5. The method for resource utilization of the aluminum fluoride silicon slag according to any one of claims 1-2, characterized in that, The concentration of the ammonia in step (2) is 25-28 wt%; The volume ratio of the fluosilicate solution to the ammonia in step (2) is 2:1-4:1; The template agent in step (2) is one of tetrapropylammonium bromide, tetrapropylammonium hydroxide and tetraethylammonium hydroxide.

6. The method of reclaiming fluoroaluminosilicate slag according to claim 1, wherein When titanium dioxide is used as the titanium source, the molar ratio of titanium in the prepared fluotitanate solution, silicon in the fluosilicate solution in step (1) and the template agent is 0.05-0.2:1:0.1-0.

3. When titanium trichloride is used as the titanium source, the molar ratio of titanium in the prepared fluorotitanate solution, silicon in the fluorosilicate solution of step (1) and the template is 0.02-0.1:1:0.1-0.2; When sodium fluorotitanate is used as the titanium source, the molar ratio of titanium in the prepared fluorotitanate solution, silicon in the fluorosilicate solution of step (1) and the template is 0.02-0.08:1:0.1-0.

2.

7. The method of reclaiming fluoroaluminosilicate slag according to any one of claims 1 to 2, characterized in that, The temperature of the static crystallization of step (3) is 150-230℃, and the time is 1-8 days; The temperature of the drying of the solid phase of step (3) is 50-80℃, and the time is 12-24h; The direct calcination of the precursor of step (3) is performed at 500-650℃ for 4-6h.

8. The method of reclaiming fluoroaluminosilicate slag according to claim 1, wherein The precursor of step (3) can also be subjected to condensation reflux, drying and calcination to obtain TS-1 molecular sieve.

9. The method of reclaiming fluoroaluminosilicate slag according to claim 8, characterized in that, The condensation reflux, drying and calcination are performed as follows: the precursor is added to an acid solution, subjected to condensation reflux at 40-80℃ for 2-6h, dried, and calcined at 550℃ for 4-6h. The concentration of the acid solution is 1-5mol / L. The acid solution is at least one of nitric acid solution, sulfuric acid solution, hydrochloric acid solution and acetic acid solution.

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