Preparation method and application of titanium silicalite porous water

Abstract

The invention discloses a preparation method and application of titanium silicalite porous water, and belongs to the field of materials. The preparation method comprises the following steps: S1, calcining titanium silicalite TS-1; s2, adding the calcined titanium silicalite TS-1 into water, sealing, and carrying out ultrasonic treatment to obtain a milk white concentrated solution; s3, centrifuging the milky white concentrated liquor to obtain supernate, repeating the operation, discarding the supernate after the last centrifugal cycle to obtain precipitated titanium silicalite TS-1, and dispersing the precipitated titanium silicalite TS-1 in water to obtain the titanium silicalite porous water. The preparation method is simple and easy to implement, and titanium silicalite porous water can be synthesized on a large scale. The titanium silicalite porous water is applied to photo-thermal tandem catalytic synthesis of ethylene glycol, can improve adsorption of oxygen and ethylene and promote mass transfer of the oxygen and the ethylene in water, and more importantly, the titanium silicalite porous water can enable a TS-1 catalyst to be uniformly dispersed, so that photo-physical and photo-chemical processes of the photocatalyst are regulated and controlled, and synthesis of ethylene glycol is promoted.

Description

Technical Field

[0001] The present application relates to a preparation method and application of titanium silicate zeolite porous water, belonging to the field of materials. Background Art

[0002] Ethylene glycol (EG), as an important chemical, had a global consumption of 42 million tons in 2023. Industrially, the synthesis of EG is divided into two steps. First, ethylene is oxidized to ethylene oxide (EO) using an expensive silver-based catalyst under high temperature and pressure with oxygen, and then hydrolysis is carried out using a strong acid to obtain EG. Therefore, developing green and efficient EG synthesis is a crucial research content at present. Compared with oxygen, hydrogen peroxide (H 2 O 2 ) combined with titanium silicate zeolite (TS-1) catalyst can achieve the epoxidation of ethylene and hydrolysis to EG under mild conditions.

[0003] Solar energy, as a clean and renewable energy source, using photocatalytic oxygen reduction (ORR) to prepare H 2 O 2 and coupling with TS-1 for ethylene oxidation to prepare EO is a promising method. Nevertheless, as a non-polar gas, the solubility of oxygen and ethylene in water is low and shows slow gas mass transfer, thus affecting the reaction efficiency. Summary of the Invention

[0004] The present application can synthesize titanium silicate zeolite porous water in large quantities by first calcining and then ultrasonic dispersion. The porous water matrix has a positive impact on the photophysical process. The titanium silicate zeolite porous water, as a solvent for photocatalytic H 2 O 2 synthesis, can promote the synthesis of H 2 O 2 . The titanium silicate zeolite porous water is applied in the photo-thermal tandem catalysis for EG synthesis. By using the prepared titanium silicate zeolite porous water as a solvent and thermal catalyst for the photo-thermal tandem catalysis of EG synthesis, the synthesis of EG can be promoted. The titanium silicate zeolite porous water can not only enhance the adsorption of oxygen and ethylene and promote their mass transfer in water, but more importantly, it can evenly disperse the TS-1 catalyst, thereby regulating the photophysical and photochemical processes of the photocatalyst, thus promoting the synthesis of EG.

[0005] According to the first aspect of the present application, a preparation method of titanium silicate zeolite porous water is provided. By first calcining and then ultrasonic dispersion, titanium silicate zeolite porous water can be synthesized in large quantities.

[0006] A preparation method of titanium silicate zeolite porous water, the preparation method comprising:

[0007] S1 Calcining the titanium silicate zeolite TS-1;

[0008] S2 Add the calcined titanium silicalite TS-1 into water, seal it, and perform ultrasonic treatment to obtain a milky white concentrated solution.

[0009] S3 Centrifuge the milky white concentrated solution to obtain the supernatant. Repeat the operation. After the last centrifugation cycle, discard the supernatant to obtain the precipitated titanium silicalite TS-1, and disperse it in water to obtain titanium silicalite porous water.

[0010] Optionally, in step S1, the conditions for the calcination are: in an air atmosphere, the temperature is 500-600 °C, and the time is 6-15 h.

[0011] Optionally, in step S2, the mass-volume ratio of the calcined titanium silicalite TS-1 to water is 1 g: 15-25 mL.

[0012] Optionally, in step S2, the conditions for the ultrasonic treatment are: the frequency is 30-50 kHz, and the time is 5-10 days.

[0013] Optionally, shake well every 6-10 h during the ultrasonic treatment.

[0014] Optionally, in step S3, the rotation speed for centrifugation is 500-2000 rpm, and the centrifugation time is 3-20 min.

[0015] Optionally, in step S3, the number of centrifugation cycles is 3-6 times.

[0016] Optionally, in step S3, the rotation speed for the last centrifugation is 7000-9000 rpm, and the centrifugation time is 10-20 min.

[0017] According to the second aspect of the present application, there is provided an application of titanium silicalite porous water in photocatalytic H 2 O 2 synthesis.

[0018] The application of the titanium silicalite porous water prepared by the above-mentioned preparation method in photocatalytic H 2 O 2 synthesis.

[0019] According to the third aspect of the present application, there is provided an application of titanium silicalite porous water in photo-thermal tandem catalysis for ethylene glycol synthesis.

[0020] The application of the titanium silicalite porous water prepared by the above-mentioned preparation method in photo-thermal tandem catalysis for ethylene glycol synthesis. In the one-pot preparation of ethylene glycol from ethylene oxide, the titanium silicalite porous water serves as a solvent and a thermal catalyst, coupling with a photocatalyst to in-situ oxidize ethylene to ethylene oxide, and then ethylene oxide is hydrolyzed to obtain ethylene glycol.

[0021] The beneficial effects that can be produced by this application include:

[0022] The preparation method and application of titanium-silicate zeolite porous water provided by this application. The preparation method is simple and easy to implement, and can synthesize titanium-silicate zeolite porous water in large quantities. This titanium-silicate zeolite porous water is applied in the photo-thermal tandem catalysis for ethylene glycol synthesis. It can not only enhance the adsorption of oxygen and ethylene and promote their mass transfer in water, but more importantly, it can evenly disperse the TS-1 catalyst, thereby regulating the photophysical and photochemical processes of the photocatalyst, and thus promoting the synthesis of ethylene glycol. Brief Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of TS-1 used in Example 1 of the present invention;

[0024] Figure 2 It is a digital picture of TS-1-MPW prepared in Example 1 of the present invention;

[0025] Figure 3 It is a test result diagram of oxygen and ethylene adsorption of TS-1-MPW and water prepared in Example 1 of the present invention;

[0026] Figure 4 It is a test result diagram of rotating disk electrode voltammogram of TS-1 porous water and water with concentrations of 10, 20, and 30 mg mL -1 prepared in Example 1 of the present invention;

[0027] Figure 5 It is a photocatalytic H 2 O 2 synthesis performance diagram of TS-1-MPW prepared in Example 1 of the present invention, TPA+@TS-1-MPW prepared in Comparative Example 1, and water;

[0028] Figure 6 It is a photo-thermal tandem catalytic synthesis performance diagram of ethylene glycol of TS-1-MPW prepared in Example 1 of the present invention, TPA+@TS-1-MPW prepared in Comparative Example 1, and TS-1 + water. Detailed Description of the Embodiments

[0029] The following describes this application in detail with reference to the embodiments, but this application is not limited to these embodiments.

[0030] Unless otherwise specified, the raw materials and catalysts in the embodiments of this application are all purchased through commercial channels.

[0031] Unless otherwise specified, the test methods are all conventional methods, and the instrument settings are all the settings recommended by the manufacturer.

[0032] The TS-1 and TPA + @TS-1 used are from Pioneer Nano.

[0033] The COF photocatalyst was synthesized according to the method in the literature Adv. Sci. 2023, 2304697.

[0034] 600 MHz 1 The instrument model of the 1H-NMR spectrometer is JNM-ECZ600R, JEOL.

[0035] The instrument used for the adsorption tests of oxygen and ethylene is Micromeritics MicroActive 3Flex3500.

[0036] The instrument used for the rotating disk electrode voltammetry test is Zahner (IM6). The analysis process is as follows: The well-ground Pt / C (20 wt%, 5 mg) catalyst is mixed with 990 μL of ethanol and 10 μL of Nafion resin solution under ultrasound for 1 hour to fully disperse the sample. 10 μL of this dispersion is dropped onto a glassy carbon RDE electrode with a diameter of 5 mm (geometric surface area of 0.196 cm 2 ). Before use, the glassy carbon electrode is polished with 0.3 μm alumina powder, rinsed with a large amount of ultrapure water and absolute ethanol, and then dried in air. After dropping the dispersion, the electrode is naturally dried in air, wetted with a small amount of ultrapure water, and then immersed in the sample solution. The RDE test is recorded by an electrochemical workstation (IM6) for voltage and current. A platinum mesh electrode and an Ag / AgCl electrode are used as the counter electrode and reference electrode, respectively. The working electrode is immersed in porous water containing different concentrations of TS-1 (solvent: 0.5 M phosphate buffer). Before the test, each sample solution is first saturated with N 2 gas, and then the working electrode is pretreated. An anodic scan is started from the open circuit potential, with a potential range of -0.05 V to 1.45 V (Vs. RHE). The scan rate is 50 mV s -1 , the electrode rotation rate is 0 rpm, and it lasts for 10 cycles. Subsequently, the sample solution is saturated with O 2 gas. During this period, the working electrode is not immersed in the sample solution but is kept wet with ultrapure water to avoid stratification. Then, under the condition of continuous oxygen bubbling, a single cyclic voltammetry scan is collected for the O -1 -saturated sample solution at a scan rate of 5 mV s 2 and an electrode rotation rate of 1600 rpm in the potential range of 0.15 to 1.25 V Vs RHE).

[0037] Example 1

[0038] Preparation method of TS-1 porous water:

[0039] We calcined TS-1 in an air atmosphere at 550 °C for 10 h. Then, the calcined TS-1 (1 g) was added to a 30 mL glass bottle and H 2 O (20 mL) was added, and finally, it was sealed with a Teflon cap. After that, it was ultrasonically treated in an ultrasonic bath at a frequency of 40 kHz for 1 week, and manually shaken every 8 h during this period. After the ultrasonic treatment was completed, the milky thick liquid was transferred to a 50 mL centrifuge tube. Then, it was centrifuged at 1500 rpm for 15 minutes. After the supernatant was transferred to a new centrifuge tube, the dispersion was centrifuged three times at a speed of 1500 rpm for 5 minutes each time, and the supernatant was poured into a new tube each time. After the last centrifugation cycle, it was centrifuged at 7830 rpm for 15 minutes. TS-1 was washed once with water, the supernatant was discarded, and the precipitated TS-1 was redispersed in ultrapure water to obtain TS-1 porous water with different concentrations. In this example, the synthesized concentrations were 10, 20, and 30 mg mL -1 of TS-1 porous water, and the TS-1 porous water with a concentration of 20 mg mL -1 was denoted as TS-1-MPW.

[0040] Figure 1 Figure 1 shows the structural schematic diagram of the TS-1 used. It can be seen that the silanols on the outer surface, due to their hydrophilicity, maintain the uniform dispersion of TS-1 nanoparticles and improve the stability of the porous water; the silicon-oxygen-silicon bonds on the inner surface, due to their hydrophobicity, can prevent the invasion of water, laying the foundation for gas adsorption.

[0041] Figure 2 Figure 2 shows the digital image of TS-1-MPW. It can be seen that TS-1-MPW is uniformly and stably dispersed and there is no obvious sedimentation.

[0042] Comparative Example 1

[0043] According to the same method as in Example 1, TS-1 was replaced with TS-1 containing TPA cations (TPA + @TS-1), without any calcination treatment. TPA + @TS-1 (1 g) was added to a 30 mL glass bottle and H 2 O (20 mL) was added, and finally, it was sealed with a Teflon cap. After that, it was ultrasonically treated in an ultrasonic bath at a frequency of 40 kHz for 1 week, and manually shaken every 4 h during this period. After the ultrasonic treatment was completed, the milky thick liquid was transferred to a 50 mL centrifuge tube. Then, it was centrifuged at 1000 rpm for 10 minutes. After the supernatant was transferred to a new centrifuge tube, the dispersion was centrifuged three times at speeds of 500, 750, and 1000 rpm for 3 minutes each time, and the supernatant was poured into a new tube each time. After the last centrifugation cycle, it was centrifuged at 8000 rpm for 15 minutes. TPA +@TS-1 once, discard the supernatant, and the precipitated TPA + @TS-1 is redispersed in ultrapure water to obtain TPA with different concentrations + @TS-1 colloidal aqueous solution. In this comparative example, the synthesized concentrations of TPA are 10, 20, and 30 mg / mL -1 respectively + @TS-1 porous water, among which the concentration of TPA is 20 mg / mL -1 respectively + @TS-1 porous water is denoted as TPA + @TS-1-MPW

[0044] Test Example 1

[0045] Perform oxygen and ethylene adsorption tests on the TS-1-MPW prepared in Example 1

[0046] Figure 3 As the oxygen and ethylene adsorption test results diagram of TS-1-MPW and water, it can be seen that compared with pure water, TS-1-MPW has higher oxygen and ethylene adsorption amounts

[0047] Perform rotating disk electrode voltammogram tests on the TS-1 porous water with concentrations of 10, 20, and 30 mg / mL prepared in Example 1 -1 respectively

[0048] Figure 4 As the rotating disk electrode voltammetry test results diagram of the TS-1 porous water with concentrations of 10, 20, and 30 mg / mL prepared in Example 1 of the present invention and water, where KPi(0.5M) represents a phosphate buffer solution with a pH of 7.0 and a concentration of 0.5 mol / L -1 respectively. It can be seen that compared with the aqueous solution, the addition of TS-1 can increase the current density -1 respectively

[0049] Test Example 2

[0050] Disperse the COFs photocatalyst (4 mg) in 15 mL of TS-1-MPW in a quartz reactor and sonicate for 30 minutes. Degas the quartz reactor with a vacuum pump and then refill it with oxygen. Repeat this process three times. After the last cycle, refill the flask with oxygen (1.0 atm). Keep the reaction solution at 25 °C, stir for 30 minutes, and irradiate it under a Xe lamp with a λ≥400 nm cut-off filter. Finally, use Ce 2 SO 4 titration method to quantify the concentration of the generated H 2 O 2 generated. And after 60 minutes of reaction, titrate again to test the generated H 2 O2 concentration.

[0051] Operate according to the above steps, and replace TS-1-MPW with TPA prepared in Comparative Example 1 + @TS-1-MPW and water, and test their photocatalytic H 2 O 2 synthesis performance diagram. As Figure 5 shown, it can be seen that compared with water and TPA + @TS-1-MPW, TS-1-MPW porous water is more conducive to promoting H 2 O 2 photocatalytic efficiency.

[0052] Test Example 3

[0053] Disperse the COFs photocatalyst (4 mg) in 15 mL of TS-1-MPW in a quartz reactor and sonicate for 30 minutes. Degas the quartz reactor with a vacuum pump, and then refill it with oxygen and ethylene. This process is repeated three times. After the last cycle, refill oxygen and ethylene (1.0 atm, molar ratio of oxygen to ethylene is 1:1) into the flask. Keep the reaction solution at 25 °C, stir for 30 minutes, and irradiate it under a Xe lamp with a λ≥400 nm cut-off filter. After the photocatalytic reaction is completed, the suspension is filtered through a 0.45 μm nylon 66 filter to remove the photocatalyst particles. Using D 2 O and DMSO as the locking solvent and internal standard respectively, mix 600 μL of the photocatalytic solution with 80 μL of D 2 O and 0.08 μL of dimethyl sulfoxide (DMSO) as the internal standard, and determine the concentration of EG on a 600 MHz 1 1H NMR.

[0054] Operate according to the above steps, and replace TS-1-MPW with TPA prepared in Comparative Example 1 + @TS-1-MPW, TS-1 + water, and test their performance of photocatalytic and photothermal tandem catalytic synthesis of ethylene glycol. As Figure 6 shown, it can be seen that compared with TPA + @TS-1-MPW and the direct mixture of TS-1 and water (TS-1 + water), TS-1-MPW porous water has higher ethylene glycol synthesis performance.

[0055] The above are only several embodiments of the present application, and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the technical solution of the present application, making some changes or modifications using the disclosed technical content above is equivalent to equivalent implementation cases, and all belong to the scope of the technical solution.

Claims

1. A method for preparing titanium silicalite porous water, characterized in that: The preparation method comprises: S1 calcining titanium silicalite TS-1; S2: adding the calcined titanium silicalite TS-1 into water, sealing the water, and then subjecting the water to ultrasonic treatment to obtain a milky white concentrated solution; S3 centrifuges the milky white concentrated solution to obtain a supernatant, repeats the operation, and after the last centrifugal cycle, discards the supernatant to obtain precipitated titanium silicalite TS-1, which is dispersed in water to obtain titanium silicalite porous water.

2. The preparation method according to claim 1, characterized in that: In step S1, the calcination conditions are: in an air atmosphere, the temperature is 500-600° C., and the time is 6-15 hours.

3. The preparation method according to claim 1, characterized in that: In step S2, the mass volume ratio of the calcined titanium silicalite TS-1 and water is 1 g: 15-25 mL.

4. The preparation method according to claim 1, characterized in that: In step S2, the conditions for ultrasonic treatment are: frequency of 30 to 50 kHz and time of 5 to 10 days.

5. The preparation method according to claim 4, characterized in that: During ultrasound, shake the mixture every 6 to 10 hours.

6. The preparation method according to claim 1, characterized in that: In step S3, the centrifugal speed is 500-2000 rpm, and the centrifugal time is 3-20 min.

7. The preparation method according to claim 1, characterized in that: In step S3, the number of centrifugal cycles is 3 to 6 times.

8. The preparation method according to claim 1, characterized in that: In step S3, the rotation speed of the last centrifugation is 7000-9000 rpm, and the centrifugation time is 10-20 min.

9. Use of the titanium silicalite porous water prepared by the preparation method according to any one of claims 1 to 8 in photocatalytic H2O2 synthesis.

10. Use of the titanium silicalite porous water prepared by the preparation method according to any one of claims 1 to 8 in the synthesis of ethylene glycol by photo-thermal tandem catalysis, characterized in that: In the one-pot oxidation of ethylene to ethylene glycol, porous water of titanium silicalite is used as solvent and thermal catalyst, coupled with photocatalyst to in situ oxidize ethylene to ethylene oxide, and then ethylene oxide is hydrolyzed to obtain ethylene glycol.

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