Preparation method of TS-1 molecular sieve material with high-activity hexa-coordinated titanium species and method for photocatalytic degradation of tetracycline by TS-1 molecular sieve material

Abstract

The invention discloses a preparation method of a TS-1 molecular sieve with high-activity hexa-coordinated titanium species and application of the TS-1 molecular sieve in photocatalytic degradation of tetracycline, the preparation method comprises the following steps: stirring and mixing a silicon source, a titanium source, H2O, an organic template agent and a hydroxyl radical initiator, and carrying out hydrolytic dispersion to obtain a uniform system; and crystallizing the uniform system to obtain the titanium silicalite molecular sieve with high-activity hexa-coordinated titanium species, and washing, drying and calcining the molecular sieve to finally obtain the titanium-silicon skeleton molecular sieve material with high-activity hexa-coordinated titanium species. The preparation method provided by the invention is a one-pot hydrothermal method, the preparation method is simple, convenient and easy to operate, rich. OH can be generated after a hydroxyl radical initiator is introduced into a system, the titanium silicalite molecular sieve synthesized by the method is relatively high in crystallinity and contains a large amount of TiO6 species, tetracycline can be degraded through weak ultraviolet light (2-4mW / cm < 2 >), and the tetracycline can be recycled. The degradation efficiency of tetracycline is improved.

Description

Technical Field

[0001] The present invention discloses a technology related to photocatalytic degradation of pollutants, and particularly relates to a preparation method of a TS-1 molecular sieve material with highly active six-coordinated titanium species and a method for photocatalytic degradation of tetracycline by using the same. Background Art

[0002] Antibiotics such as macrolides, quinolones, and tetracyclines are widely used to control microbial infections in animals and humans. Although there are a large number of residual antibiotics in the aquatic ecosystem, due to the continuous discharge of antibiotics and their inherent long-term persistence, they will have an adverse impact on the ecological environment and human life. Therefore, it is urgent to develop effective technologies to eliminate antibiotics in water.

[0003] Photodegradation technology has become a promising method for removing antibiotics from wastewater. The photoreaction is a rapid, mild, and harmless reaction process, which is widely regarded as a promising sustainable technology. Among all photocatalysts, heteroatom molecular sieves have attracted people's attention. They have a porous structure with regular channels and cavities and are widely used as catalysts and adsorbents in various industrial applications. As one of the most successful industrial catalysts, titanium silicate molecular sieve TS-1 has been proven to be an effective photocatalyst in pollutant degradation or oxidation reactions. Although TS-1 molecular sieve shows great potential in the photocatalytic degradation of antibiotics, due to the different hydrolysis rates of titanium source and silicon source, the mismatch between the crystallization rate of the molecular sieve and the binding rate of Ti, and the uneven distribution of titanium precursors on the surface or in the pores of the molecular sieve, the synthesis of TS-1 faces great challenges. Summary of the Invention

[0004] In view of this, the present invention provides a preparation method of a TS-1 molecular sieve material with highly active six-coordinated titanium species and a method for photocatalytic degradation of tetracycline by using the same, so as to obtain a catalyst with high crystallinity, high activity, and high stability, and apply it to the photocatalytic degradation of tetracycline, showing excellent catalytic effects.

[0005] On the one hand, the present invention provides a preparation method of a TS-1 molecular sieve material with highly active six-coordinated titanium species, including:

[0006] S1: Hydrolysis and dispersion: Stir and mix a silicon source, a titanium source, H2O, an organic template agent, and a hydroxyl radical initiator, and perform hydrolysis and dispersion to obtain a homogeneous system; wherein the hydroxyl radical initiator is a Na2S2O8 solution;

[0007] S2: Crystallization: Transfer the homogeneous system to a reaction kettle for crystallization to obtain a TS-1 molecular sieve;

[0008] S3: Washing and drying: Wash the TS-1 molecular sieve until it is neutral and then dry it to obtain a dried TS-1 molecular sieve;

[0009] S4: Calcination: Remove the organic template agent of the dried TS-1 molecular sieve by high-temperature calcination to finally obtain a TS-1 molecular sieve material with highly active six-coordinated titanium species.

[0010] Preferably, the silicon source is tetraethyl orthosilicate; the titanium source is tetrabutyl titanate; the organic template agent is tetrapropylammonium hydroxide.

[0011] Preferably, the molar ratio of the silicon source, titanium source, H2O, and organic template agent in the homogeneous system is 1:0.025:30:0.3, the concentration of the Na2S2O8 solution is 0 - 0.12 mol / L, and the content of TiO6 species is adjusted by changing the concentration of the Na2S2O8 solution in the system.

[0012] Preferably, the crystallization reaction occurs in a stainless-steel autoclave with a polytetrafluoroethylene lining, the reaction temperature is 170 °C, and the reaction time is 2 days.

[0013] Preferably, the high-temperature calcination is carried out in a muffle furnace at 550 °C, and the calcination time is 5 h.

[0014] On the other hand, the present invention also provides an application of the TS-1 molecular sieve material with highly active six-coordinated titanium species prepared by the preparation method in photocatalytic degradation of organic pollutants.

[0015] The organic pollutant is tetracycline; using the TS-1 molecular sieve material with highly active six-coordinated titanium species as a catalyst, under the irradiation of a 6W, 254 nm (2 - 4 mW / cm 2 ) ultraviolet lamp, the TS-1 molecular sieve material is contacted with the tetracycline solution in a reactor for photocatalytic degradation.

[0016] The present invention provides a preparation method of a TS-1 molecular sieve material with highly active six-coordinated titanium species and a method for photocatalytic degradation of tetracycline. The preparation method is a one-pot hydrothermal method, which is simple and easy to operate. After introducing Na2S2O8 into the system, abundant ·OH can be generated. The titanium silicate molecular sieve synthesized by this method has a high crystallinity, contains a large number of TiO6 species, and can degrade tetracycline by weak ultraviolet light (2 - 4 mW / cm 2 ) to improve the degradation efficiency of tetracycline.

[0017] This method is expected to be applied in wastewater treatment and fine chemical production, and has special significance both from a theoretical perspective and a practical perspective.

[0018] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the disclosure of the present invention. Description of the Drawings

[0019] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing embodiments in accordance with the present invention, and are used together with the specification to explain the principles of the present invention.

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings required for use in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those of ordinary skill in the art, other accompanying drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 XRD pattern of the titanium silicalite molecular sieve material with highly active six-coordinated titanium species provided for the disclosed embodiments of the present invention;

[0022] Figure 2 UV-vis pattern of the titanium silicalite molecular sieve material with highly active six-coordinated titanium species provided for the disclosed embodiments of the present invention;

[0023] Figure 3 Photodegradation pattern of tetracycline on the titanium silicalite molecular sieve material with highly active six-coordinated titanium species provided for the disclosed embodiments of the present invention. Detailed Embodiments

[0024] The present invention will be further explained below in conjunction with specific implementation schemes, but it is not used to limit the protection scope of the present invention.

[0025] In the prior art, when synthesizing the titanium silicalite molecular sieve material with six-coordinated titanium species, a microwave-assisted synthesis method and an amino acid-assisted strategy were adopted and applied in dibenzothiophene oxidative desulfurization and hexene epoxidation, but there was no other synthesis strategy and its application in the photocatalytic degradation of tetracycline reaction;

[0026] For this reason, first, this implementation scheme provides a preparation method of a TS-1 molecular sieve material with highly active six-coordinated titanium species, including the following steps:

[0027] Hydrolysis and dispersion: Stir and mix a silicon source, a titanium source, H2O, an organic template agent, and a hydroxyl radical initiator, and perform hydrolysis and dispersion to obtain a homogeneous system;

[0028] Crystallization: Transfer the homogeneous system to a reaction kettle for crystallization to obtain a TS-1 molecular sieve;

[0029] Washing and drying: Wash the molecular sieve to neutral and then dry it to obtain a dried molecular sieve;

[0030] Calcination: The organic template agent of the molecular sieve is removed by high-temperature calcination, and finally a titanium-silicon molecular sieve material with highly active six-coordinated titanium species is obtained. The obtained molecular sieve material is composed of a titanium-silicon framework and is a molecular sieve material with an MFI topological structure.

[0031] Preferably, the above-mentioned silicon source is tetraethyl orthosilicate.

[0032] Preferably, the above-mentioned titanium source is tetrabutyl titanate.

[0033] Preferably, the above-mentioned organic template agent is tetrapropylammonium hydroxide.

[0034] Preferably, the molar ratio of the silicon source, titanium source, H2O, and organic template agent in the above homogeneous system is 1:0.025:30:0.3.

[0035] The above-mentioned hydroxyl radical initiator is a Na2S2O8 solution; preferably, the concentration of the Na2S2O8 solution in the above homogeneous system is 0 - 0.12 mol / L. Among them, by changing the concentration of the Na2S2O8 solution in the synthesis system, the content of TiO6 species is adjusted.

[0036] The above-mentioned crystallization reaction occurs in a stainless-steel autoclave with a polytetrafluoroethylene lining. The reaction temperature is 170 °C, and the reaction time is 2 days. Through experiments, it is verified that this temperature is the optimal temperature for the crystallization temperature.

[0037] The above-mentioned molecular sieve material after drying is subjected to high-temperature calcination in a muffle furnace at 550 °C to burn off the organic template agent therein, and the calcination time is 5 h.

[0038] In addition, this embodiment also provides an application of a TS-1 molecular sieve catalyst with highly active TiO6 species in the photocatalytic degradation of tetracycline, which is applied to the photocatalytic degradation of organic pollutants;

[0039] The titanium-silicon molecular sieve catalyst with highly active six-coordinated titanium species has the characteristics of high activity and high stability in the photocatalytic degradation of tetracycline.

[0040] The above-mentioned organic pollutant is tetracycline, specifically including the following:

[0041] Using titanium-silicon molecular sieve TS-1 as a catalyst, under the irradiation of a 6W, 254 nm (2 - 4 mW / cm 2 ) ultraviolet lamp, the titanium-silicon molecular sieve TS-1 is brought into contact with the tetracycline solution in the reactor for photocatalytic degradation.

[0042] Preferably, the concentration of the above-mentioned tetracycline solution is 10 mg / L. The content of the TS-1 molecular sieve catalyst with highly active TiO6 species is 0.6 g / L. The catalytic reaction time is 2.5 h.

[0043] Finally,Figure 2 The UV-vis diagram of the TS-1 molecular sieve with highly active TiO6 species provided by the disclosed embodiment of the present invention and the TS-1 molecular sieve material synthesized with the Na2S2O8 solution without addition. The TiO6 species can be identified by the UV-vis absorption band at 250 - 290 nm. It can be seen from the figure that the TS-1 molecular sieve synthesized with the addition of the Na2S2O8 solution contains TiO6 species.

[0044] This embodiment introduces ·OH into the system. ·OH is more effective than OH in breaking the Si-O-Si bond and accelerating the crystallization of the molecular sieve, making the hydrolysis rates of the titanium source and the silicon source match. At the same time, ·OH can promote the formation of open and highly active TiO6 species, enabling them to interact better with larger reactant molecules. Therefore, this embodiment uses Na2S2O8 to promote the synthesis of TS-1 and applies it to the photocatalytic degradation of tetracycline. - As shown in

[0045] Example 1:

[0046] According to the molar ratio of 1:0.025:30:0.3, TEOS, TBOT, H2O, and TPAOH were added to a beaker. Subsequently, the Na2S2O8 solution was added to the solution to make the concentration of Na2S2O8 in the system 0.01 mol / L, and it was stirred for 5 h to obtain a homogeneous system.

[0047] The homogeneous system obtained in the previous step was loaded into a high-temperature reaction kettle with a polytetrafluoroethylene inner lining and crystallized at 170 °C for 2 days to obtain the TS-1 molecular sieve with highly active TiO6 species.

[0048] The TS-1 molecular sieve obtained in the previous synthesis was repeatedly washed with deionized water until neutral and then placed in an oven at 60 °C for drying.

[0049] The dried TS-1 molecular sieve obtained in the previous synthesis was placed in a muffle furnace and calcined at 550 °C for 5 h to burn off the organic template agent, and finally the TS-1 molecular sieve with highly active TiO6 species was obtained, as Figure 1 shown.

[0050] It can be seen from Figure 1 that the substance synthesized in this embodiment has an MFI topological structure, is a pure-phase TS-1, and has no anatase impurity phase. As shown in the UV-vis spectrum of Figure 2 , it shows that the sample contains TiO6 species.

[0051] The TS-1 catalyst obtained in the previous step and 50 mL of 10 mg / L tetracycline were placed in a reactor and stirred, placed in the dark for 30 min, and then placed under a 6 W, 254 nm (2 - 4 mW / cm2 ) React for 2.5 h under the condition of ultraviolet lamp irradiation, and take samples every 30 min.

[0052] As Figure 3 shown, the TS-1SPS 0.01M sample has good photocatalytic degradation performance for tetracycline.

[0053] Example 2:

[0054] Change the concentration of the Na2S2O8 solution added in Example 1, so as to change the content of TiO6 species in the molecular sieve. Add TEOS, TBOT, TPAOH and H2O to the beaker, and then add the Na2S2O8 solution to the solution so that the concentration of Na2S2O8 in the system is 0.10 mol / L, and stir for 5 h to obtain a homogeneous system.

[0055] Load the homogeneous system obtained in the previous step into a high-temperature reaction kettle with a polytetrafluoroethylene liner, and crystallize at 170 °C for 2 days to obtain TS-1 molecular sieve with highly active TiO6 species.

[0056] Wash the TS-1 molecular sieve obtained in the previous synthesis with deionized water repeatedly until neutral, and place it in an oven at 60 °C for drying.

[0057] Place the dried TS-1 molecular sieve obtained in the previous synthesis in a muffle furnace and calcine at 550 °C for 5 hours to burn off the organic template agent therein, and finally obtain TS-1 molecular sieve with highly active TiO6 species, as Figure 1 shown.

[0058] It can be seen from Figure 1 that the substance synthesized in this implementation scheme has an MFI topological structure, is pure-phase TS-1, and has no anatase impurity phase. As shown in the UV-vis spectrum of Figure 2 , it shows that the sample contains TiO6 species.

[0059] Place the TS-1 catalyst obtained in the previous step and 50 mL of 10 mg / L tetracycline in the reactor and stir, place it in the dark for 30 min, and then place it under the condition of ultraviolet lamp irradiation at 6W, 254 nm (2 - 4 mW / cm 2 ) and react for 2.5 h, and take samples every 30 min.

[0060] In this example, as Figure 3 shown, the TS-1SPS 0.10M sample has the best photocatalytic degradation performance for tetracycline.

[0061] Example 3:

[0062] Continue to change the concentration of the Na2S2O8 solution added in Example 1. Add TEOS, TBOT, TPAOH, and H2O to a beaker, and then add the Na2S2O8 solution to the solution so that the concentration of Na2S2O8 in the system is 0.12 mol / L, and stir for 5 h to obtain a homogeneous system.

[0063] Load the homogeneous system obtained in the previous step into a polytetrafluoroethylene-lined high-temperature reactor, and crystallize it at 170 °C for 2 days to obtain TS-1 zeolite with TiO6 species.

[0064] Wash the TS-1 zeolite obtained in the previous synthesis step with deionized water repeatedly until neutral, and place it in an oven at 60 °C for drying.

[0065] Place the dried TS-1 zeolite obtained in the previous synthesis step in a muffle furnace and calcine it at 550 °C for 5 hours to burn off the organic template agent, and finally obtain TS-1 zeolite with TiO6 species, as Figure 1 shown.

[0066] It can be seen from Figure 1 that the substance synthesized in this embodiment has an MFI topological structure, but there are impurity phases present. As shown in the UV-vis spectrum of Figure 2 , it shows that the sample contains TiO6 species.

[0067] Place the TS-1 catalyst obtained in the previous step and 50 mL of 10 mg / L tetracycline in a reactor and stir, place it in the dark for 30 min, and then place it under the condition of ultraviolet light irradiation at 6 W and 254 nm (2 - 4 mW / cm 2 ) for 2.5 h, and take samples every 30 min.

[0068] In this example, as shown in Figure 3 , the TS-1 SPS 0.12 M sample has the performance of photocatalytic degradation of tetracycline, but the activity is poor.

[0069] Comparative Example 1:

[0070] Remove Na2S2O8 from Example 1. Add TEOS, TBOT, TPAOH, and H2O to a beaker according to the ratio in Example 1, and stir for 5 h to obtain a homogeneous system.

[0071] Load the homogeneous system obtained in the previous step into a polytetrafluoroethylene-lined high-temperature reactor, and crystallize it at 170 °C for 2 days to obtain TS-1 zeolite.

[0072] Wash the TS-1 zeolite obtained in the previous synthesis step with deionized water repeatedly until neutral, and place it in an oven at 60 °C for drying.

[0073] The dried TS-1 molecular sieve obtained in the previous synthesis step was placed in a muffle furnace and calcined at 550 °C for 5 hours to burn off the organic template agent therein, and finally the TS-1 molecular sieve was obtained, as Figure 1 shown.

[0074] It can be seen from Figure 1 that the synthesized substance in this embodiment has an MFI topological structure and is a pure-phase TS-1. As shown in the UV-vis spectrum of Figure 2 , it shows that there are no TiO6 species in the sample.

[0075] The TS-1 catalyst obtained in the previous step and 50 mL of 10 mg / L tetracycline were placed in a reactor and stirred, placed in the dark for 30 min, and then reacted under the condition of ultraviolet light irradiation at 6 W and 254 nm (2 - 4 mW / cm 2 ) for 2.5 h, and samples were taken every 30 min.

[0076] As Figure 3 shown, the photocatalytic degradation performance of the TS-1SPS 0M sample for tetracycline is much worse than that of the sample containing TiO6 species.

[0077] Those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include known common knowledge or conventional technical means in the technical field not disclosed in the present invention. The specification and examples are only regarded as exemplary, and the true scope and spirit of the present invention are pointed out by the following claims.

[0078] It should be understood that the present invention is not limited to what has been described above and can be modified and changed without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. Preparation method of TS-1 molecular sieve material with highly active six-coordinated titanium species, characterized in that, Including: S1: Hydrolysis and dispersion: Stir and mix a silicon source, a titanium source, H2O, an organic template agent, and a hydroxyl radical initiator, and perform hydrolysis and dispersion to obtain a homogeneous system; wherein the hydroxyl radical initiator is a Na2S2O8 solution; S2: Crystallization: Transfer the homogeneous system to a reaction kettle for crystallization to obtain TS-1 molecular sieve; S3: Washing and drying: Wash the TS-1 molecular sieve to neutral and then dry it to obtain a dried TS-1 molecular sieve; S4: Calcination: Remove the organic template agent of the dried TS-1 molecular sieve by high-temperature calcination to finally obtain a TS-1 molecular sieve material with highly active six-coordinated titanium species.

2. The preparation method of the TS-1 molecular sieve material with highly active six-coordinated titanium species according to claim 1, characterized in that, The silicon source is tetraethyl orthosilicate; the titanium source is tetrabutyl titanate; the organic template agent is tetrapropylammonium hydroxide.

3. The preparation method of the TS-1 molecular sieve material with highly active six-coordinated titanium species according to claim 1, characterized in that, In the homogeneous system, the molar ratio of the silicon source, the titanium source, H2O, and the organic template agent is 1:0.025:30:0.3, and the concentration of the Na2S2O8 solution is 0-0.12 mol / L. By changing the concentration of the Na2S2O8 solution in the system, the content of TiO6 species is adjusted.

4. The preparation method of the TS-1 molecular sieve material with highly active six-coordinated titanium species according to claim 1, characterized in that, The crystallization reaction occurs in a stainless steel reaction kettle with a polytetrafluoroethylene lining, the reaction temperature is 170 °C, and the reaction time is 2 days.

5. The preparation method of the TS-1 molecular sieve material with highly active six-coordinated titanium species according to claim 1, characterized in that, The high-temperature calcination is carried out in a muffle furnace at 550 °C, and the calcination time is 5 h.

6. Use of the TS-1 molecular sieve material with highly active six-coordinated titanium species prepared by the preparation method according to any one of claims 1-5, characterized in that, Applied to photocatalytic degradation of organic pollutants.

7. Use of the TS-1 molecular sieve material with highly active six-coordinate titanium species according to claim 6, characterized in that, The organic pollutant is tetracycline; using a TS-1 molecular sieve material with highly active hexacoordinate titanium species as a catalyst, under the irradiation of a 6W, 254nm (2 - 4mW / cm 2 ) ultraviolet lamp, the TS-1 molecular sieve material is brought into contact with the tetracycline solution in a reactor for photocatalytic degradation.

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