Use of iron-doped barium titanate nanoparticles in piezocatalytic reduction of nitrogen
By using iron-doped barium titanate nanoparticles to catalyze the reduction of nitrogen to ammonium or ammonia under ultrasonic vibration, the problem of low nitrogen activation efficiency in existing technologies is solved, and a highly efficient piezoelectric catalytic nitrogen reduction effect is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUZHOU UNIV
- Filing Date
- 2024-10-31
- Publication Date
- 2026-05-15
AI Technical Summary
Existing technologies struggle to efficiently activate nitrogen molecules and convert them into ammonia under environmental conditions. Piezoelectric materials lack effective reaction sites and have low charge carrier utilization.
Iron-doped barium titanate nanoparticles were used as catalysts to achieve piezoelectric catalytic reduction of nitrogen to ammonium or ammonia under ultrasonic vibration. Iron-doped barium titanate nanoparticles were prepared by solvothermal method and carried out catalytic reaction under light-protected conditions.
The nitrogen fixation and ammonia conversion efficiency of iron-doped barium titanate nanoparticles reached 66.72 μmol·g⁻¹·h⁻¹, which is much higher than that of existing piezoelectric materials, and also exhibits good piezoelectric response and stability.
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Figure CN119565614B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of inorganic nanomaterials and piezoelectric catalysis, specifically to a method for preparing iron-doped barium titanate nanoparticles and their application in piezoelectric catalytic nitrogen reduction. Background Technology
[0002] Nitrogen is the most abundant element in Earth's atmosphere and a crucial element for life. Converting nitrogen into value-added products is of great significance for improving lives and sustainable development. Currently, most ammonia is produced using the Haber-Bosch process, which has become one of the fundamental pillars of the modern chemical industry. To break the stable N≡N bond, the Haber-Bosch process typically operates under high temperature and pressure, requiring ultrapure H₂ as a feedstock. However, most commercially available hydrogen is produced through natural gas reforming, with only about 1% coming from hydrocatalytic hydrogen production. Natural gas reforming uses fossil fuels, consumes significant amounts of energy, and emits greenhouse gases. Therefore, developing an alternative ammonia production method to replace the hazardous, energy-intensive, and unsustainable Haber-Bosch process is of great importance.
[0003] Currently, much research focuses on the direct conversion of ammonia from nitrogen and water using light or electricity under ambient conditions. A major challenge in these direct conversions is the high energy barrier required for nitrogen activation: the breaking of the first bond in the nitrogen molecule requires a reduction potential of -4.16 V (compared to NHE). Research on piezoelectric-driven nitrogen fixation is still in its early stages. The main challenges for most piezoelectric materials are the lack of reaction sites for nitrogen conversion and the low utilization of charge carriers generated by piezoelectricity. Therefore, designing materials with excellent piezoelectric properties and superior catalytic activity for nitrogen fixation is crucial. Summary of the Invention
[0004] The purpose of this invention is to provide an inorganic nanomaterial of iron-doped barium titanate nanoparticles and its preparation method. Under ultrasonic vibration, piezoelectric catalytic reduction of nitrogen to ammonium ions is achieved. Experiments show that the nitrogen fixation and ammonia conversion efficiency of barium titanate (Fe-BTO-3) with a 3% iron doping ratio reaches 66.72 μmol·g⁻¹. -1 ·h -1 (830 μmol·L) -1 ·g -1 ·h -1 This is far greater than the nitrogen fixation capability of the currently reported piezoelectric material ZnO.
[0005] To achieve the above objectives, the specific technical solution of the present invention is as follows:
[0006] Application of iron-doped barium titanate nanoparticles in catalytic nitrogen reduction.
[0007] Application of iron-doped barium titanate nanoparticles in piezoelectric catalytic nitrogen reduction.
[0008] Application of iron-doped barium titanate nanoparticles in the catalytic reduction of nitrogen to ammonium or ammonia.
[0009] Preferably, the above application is carried out under light-protected conditions; the temperature of the above application is room temperature, such as 0-50°C, preferably 10-40°C, and more preferably 15-30°C.
[0010] Preferably, in the above-mentioned iron-doped barium titanate nanoparticles, the molar fraction of iron ions relative to titanium ions is 1% to 5%, and more preferably, the molar fraction of iron ions relative to titanium ions is 2% to 4%.
[0011] This invention discloses a method for preparing the above-mentioned iron-doped barium titanate nanoparticles, comprising the following steps: reacting an iron source, a titanium source, and a barium source in a solution to obtain iron-doped barium titanate nanoparticles; specifically, placing the iron source in a precursor solution containing a titanium source and a barium source, reacting, centrifuging and washing, and drying to obtain iron-doped barium titanate nanoparticles.
[0012] Preferably, in the precursor solution containing titanium and barium sources, the molar ratio of titanium to barium is 1:0.5 to 1.5, more preferably 1:0.8 to 1.4.
[0013] Preferably, the reaction temperature is 120–160°C and the reaction time is 6–24 hours.
[0014] This invention discloses a method for catalytic nitrogen reduction, comprising the following steps: using the above-mentioned iron-doped barium titanate nanoparticles to catalyze nitrogen reduction.
[0015] This invention discloses a method for catalytic reduction of nitrogen to produce ammonia or ammonium ions, comprising the following steps: using the above-mentioned iron-doped barium titanate nanoparticles to catalyze the reduction of nitrogen to produce ammonia or ammonium ions.
[0016] In this invention, the catalytic nitrogen reduction is a piezoelectric catalytic nitrogen reduction, which does not require light irradiation; specifically, a solution containing iron-doped barium titanate nanoparticles is ultrasonically treated and nitrogen gas is introduced, resulting in piezoelectric catalytic nitrogen reduction and the generation of ammonium ions.
[0017] Advantages of this invention:
[0018] This invention discloses the preparation of iron-doped barium titanate nanoparticles and their application in piezoelectric catalytic nitrogen reduction to ammonia. The iron-doped barium titanate nanoparticles exhibit stable and excellent catalytic performance and a simple method in piezoelectric catalytic nitrogen reduction to ammonia. Moreover, the iron-doped barium titanate nanoparticles have enhanced piezoelectric response in piezoelectric catalytic nitrogen reduction to ammonia.
[0019] This invention discloses for the first time a method for applying iron-doped barium titanate nanoparticles to piezoelectric nitrogen fixation, which effectively enhances the adsorption of nitrogen gas and, combined with excellent piezoelectric properties, gives the material good nitrogen fixation performance. Attached Figure Description
[0020] Figure 1 This is a transmission electron microscope (TEM) image of Fe-BTO-3 nanoparticles.
[0021] Figure 2 This is a diagram showing the effect of barium titanate nanoparticles and Fe-BTO-x piezoelectric catalytic nitrogen reduction.
[0022] Figure 3 The curve shows the relationship between the reduction of nitrogen by Fe-BTO-3 piezoelectric catalyst and time.
[0023] Figure 4 The X-ray diffraction pattern and transmission electron microscope image are shown after 5 cycles of the Fe-BTO-3 piezoelectric catalytic nitrogen reduction experiment. Detailed Implementation
[0024] This invention discloses the application of iron-doped barium titanate nanoparticles in piezoelectric catalytic nitrogen reduction to ammonia. Pure barium titanate nanoparticles and iron-doped barium titanate nanoparticles (Fe-BTO) are obtained by a simple solvothermal method, and piezoelectric catalytic reduction of nitrogen to ammonium or ammonia is achieved under ultrasonic vibration.
[0025] This invention obtains pure barium titanate nanoparticles (BTO) and barium titanate nanoparticles with different iron doping amounts (Fe-BTO-x, x=1~5, preferably 1, 3, 5) through a simple solvothermal method.
[0026] The present invention discloses a method for the piezoelectric catalytic reduction of barium titanate nanoparticles to ammonia, comprising the following steps: during nitrogen reduction, the barium titanate nanoparticles are placed in deionized water and nitrogen is introduced, followed by ultrasonic treatment, and the generation of ammonium ions is detected by the Nessler reagent colorimetric method.
[0027] The preparation method of iron-doped barium titanate nanoparticles of the present invention includes the following steps: placing an iron source in a precursor solution containing a titanium source and a barium source, reacting, centrifuging and washing, and drying to obtain iron-doped barium titanate nanoparticles.
[0028] In this invention, tetrabutyl titanate (C 16 H 36 Using O4Ti as the titanium source and barium nitrate (Ba(NO3)2) as the barium source, precursor solutions containing titanium and barium sources were obtained by dissolving them in n-butanol and deionized water, respectively; C 16 H 36The molar ratios of O4Ti to Ba(NO3)2 are 1:0.8, 1:1, 1:1.2, and 1:1.4, with C being the preferred molar ratio. 16 H 36 The molar ratio of O4Ti to Ba(NO3)2 is 1:1; the solvothermal reaction is carried out in a reactor at 120-160℃ for 6-24 hours, with the preferred condition being 135℃ for 18 hours.
[0029] In this invention, based on the preparation method of barium titanate nanoparticles, an iron source is added as a dopant, and barium titanate nanoparticles (Fe-BTO-x) with different iron doping amounts are prepared by controlling the amount of iron. Specifically, ferric nitrate nonahydrate (Fe(NO3)3·9H2O) is selected as the iron source, and the molar fraction of iron ions relative to titanium ions is 1%, 3%, and 5%. Preferably, the molar fraction of iron ions is 3%.
[0030] As an example, the present invention adds the above-mentioned pure BTO and Fe-BTO (50 mg each) to 100 mL of deionized water, evacuates the water, and then introduces nitrogen gas at flow rates of 20, 30 and 40 mL / min, with the preferred condition being 30 mL / min, to achieve the purpose of reducing nitrogen gas to ammonium ions under ultrasonic vibration.
[0031] The following experiments illustrate the technological advancements of this invention. The raw materials involved are conventional products in the field, and the specific preparation operations and performance tests are all conventional techniques.
[0032] Example 1: Preparation of barium titanate nanoparticles. The specific steps are as follows:
[0033] (1) Weigh 522.7 mg of barium nitrate and dissolve it in 10 mL of deionized water, then disperse it by ultrasonication;
[0034] (2) Weigh 1 g of NaOH and add it to 10 mL of deionized water;
[0035] (3) Take 0.68 mL of tetrabutyl titanate solution and add it dropwise to 10 mL of n-butanol solution, then stir to mix;
[0036] (4) Add 5 mL of oleic acid to 10 mL of n-butanol;
[0037] The four solutions were mixed sequentially to obtain a white emulsion. After stirring, the emulsion was transferred to a 100 mL high-pressure reactor and reacted at 135 °C for 18 hours. After the reaction was completed, the product was washed six times with an ethanol:water = 1:1 solution, with one wash in between using 5% acetic acid. Finally, the product was dried at 60 °C for 12 hours to obtain pure barium titanate nanoparticles.
[0038] Example 2: Preparation of Fe-BTO-3 nanoparticles, the specific steps are as follows:
[0039] (1) Weigh 522.7 mg of barium nitrate and 24.24 mg of ferric nitrate nonahydrate and dissolve them in 10 mL of deionized water, then disperse by ultrasonication;
[0040] (2) Weigh 1 g of NaOH and add it to 10 mL of deionized water;
[0041] (3) Take 0.66 mL of tetrabutyl titanate solution and add it dropwise to 10 mL of n-butanol solution, then stir to mix;
[0042] (4) Add 5 mL of oleic acid to 10 mL of n-butanol;
[0043] The four solutions were mixed sequentially to obtain a white emulsion. After stirring, the emulsion was transferred to a 100 mL high-pressure reactor and reacted at 135 °C for 18 hours. After the reaction was completed, the product was washed six times with an ethanol:water = 1:1 solution, with one wash in between using 5% acetic acid. Finally, the product was dried at 60 °C for 12 h to obtain Fe-BTO-3 nanoparticles with a molar fraction of 3% iron ions.
[0044] Appendix Figure 1 The image shows a transmission electron microscope (TEM) image of the Fe-BTO-3 nanoparticles. The particle size of the Fe-BTO-3 nanoparticles is approximately 10 nm.
[0045] Example 3: Preparation of Fe-BTO-1 nanoparticles, the specific steps are as follows:
[0046] (1) Weigh 522.7 mg of barium nitrate and 8.08 mg of ferric nitrate nonahydrate and dissolve them in 10 mL of deionized water, then disperse by ultrasonication;
[0047] (2) Weigh 1 g of NaOH and add it to 10 mL of deionized water;
[0048] (3) Take 0.673 mL of tetrabutyl titanate solution and add it dropwise to 10 mL of n-butanol solution, then stir to mix;
[0049] (4) Add 5 mL of oleic acid to 10 mL of n-butanol;
[0050] The four solutions were mixed sequentially to obtain a white emulsion. After stirring, the emulsion was transferred to a 100 mL high-pressure reactor and reacted at 135 °C for 18 hours. After the reaction was completed, the product was washed six times with an ethanol:water = 1:1 solution, with one wash in between using 5% acetic acid. Finally, the product was dried at 60 °C for 12 hours to obtain Fe-BTO-1 nanoparticles.
[0051] Example 4: Preparation of Fe-BTO-5 nanoparticles, the specific steps are as follows:
[0052] (1) Weigh 522.7 mg of barium nitrate and 40.40 mg of ferric nitrate nonahydrate and dissolve them in 10 mL of deionized water, then disperse by ultrasonication;
[0053] (2) Weigh 1 g of NaOH and add it to 10 mL of deionized water;
[0054] (3) Take 0.646 mL of tetrabutyl titanate solution and add it dropwise to 10 mL of n-butanol solution, then stir to mix;
[0055] (4) Add 5 mL of oleic acid to 10 mL of n-butanol;
[0056] The four solutions were mixed sequentially to obtain a white emulsion. After stirring, the emulsion was transferred to a 100 mL high-pressure reactor and reacted at 135 °C for 18 hours. After the reaction was completed, the product was washed six times with an ethanol:water = 1:1 solution, with one wash in between using 5% acetic acid. Finally, the product was dried at 60 °C for 12 hours to obtain Fe-BTO-5 nanoparticles.
[0057] Example 5: Piezoelectric Catalytic Nitrogen Reduction Experiment with Different Catalysts
[0058] 50 mg of catalyst was dispersed in 100 ml of deionized water in a glass reactor, which was fixed in an ultrasonic cleaner (45 kHz, power: 300 W). After vacuuming, the solution was bubbled with pure N2 in the dark for 0.5 h, and then ultrasonic vibration was started at a fixed temperature (20 °C). Every 1 h, 5 ml of the suspension was taken and the ammonia concentration was checked by the Nessler reagent colorimetric method.
[0059] The catalysts were barium titanate alone, Fe-BTO-1, Fe-BTO-3, and Fe-BTO-5, and their nitrogen reduction effects are shown in the figure below. Figure 2 As shown; Figure 3 The curves show the relationship between nitrogen reduction by piezoelectric catalysis of Fe-BTO-3 and time. The nitrogen fixation and ammonia conversion efficiency of barium titanate (Fe-BTO-3) with a 3% iron doping ratio reached 66.72 μmol·g. -1 ·h -1 (equivalent to 830 μmol·L) -1 ·g -1 ·h -1 It is 7.5 times that of pure BTO, and its performance is far superior to the nitrogen fixation ability of the currently reported piezoelectric material ZnO (3.60 μmol·g). -1 ·h -1 ).
[0060] Example 6: Stability Test of Fe-BTO-3 Structure
[0061] In Example 6, the material recovered after 4 hours of sonication was washed sequentially with deionized water and 95% ethanol, dried in a vacuum oven, and then redispersed in 100 ml of deionized water in a glass reactor. The reactor was fixed in an ultrasonic cleaner (45 kHz, power: 300 W). After evacuation, the solution was bubbled with pure N2 in the dark for 0.5 hours, and then sonication was started at a fixed temperature (20°C). Every hour, 5 ml of the suspension was taken, and the ammonia concentration was checked using the Nessler reagent colorimetric method. The above steps were repeated 5 times to separate the material. The morphology of the sample was characterized by transmission electron microscopy, and the structure of the material was characterized by X-ray diffraction (XRD). See attached... Figure 4 As shown, the material morphology retains a nanoparticle structure of approximately 10 nm, and the XRD peaks remain unchanged. Therefore, this catalyst can be reused and exhibits good structural stability.
[0062] This invention discloses for the first time a method for preparing inorganic perovskite nanomaterials that utilizes mechanical energy vibration for nitrogen reduction without light exposure. Experiments show that barium titanate (Fe-BTO-3) with a 3% iron doping ratio achieves a nitrogen fixation-to-ammonia conversion efficiency of 66.72 μmol·g⁻¹. -1 ·h -1 (830 μmol·L) -1 ·g -1 ·h -1 This is far higher than the nitrogen fixation capability of currently reported piezoelectric materials.
Claims
1. The application of iron-doped barium titanate nanoparticles in the piezoelectric catalytic reduction of nitrogen to ammonia or ammonium, characterized in that, In the iron-doped barium titanate nanoparticles, the molar fraction of iron ions relative to titanium ions is 3%. The preparation method of the iron-doped barium titanate nanoparticles includes the following steps: reacting an iron source, a titanium source, and a barium source in a solution at 135°C for 18 hours to obtain iron-doped barium titanate nanoparticles; using tetrabutyl titanate as the titanium source and barium nitrate as the barium source, dissolving them in n-butanol and deionized water respectively to obtain a precursor solution containing the titanium source and the barium source; the molar ratio of tetrabutyl titanate to barium nitrate is 1:
1.
2. The application according to claim 1, characterized in that, Iron-doped barium titanate nanoparticles are placed in deionized water and nitrogen gas is introduced. The nitrogen gas is then reduced by piezoelectric catalysis to produce ammonia or ammonium ions.
3. A method for catalytic reduction of nitrogen to produce ammonia or ammonium ions, comprising the following steps: using iron-doped barium titanate nanoparticles for piezoelectric catalytic reduction of nitrogen to produce ammonia or ammonium ions; wherein the molar fraction of iron ions relative to titanium ions in the iron-doped barium titanate nanoparticles is 3%; the preparation method of the iron-doped barium titanate nanoparticles comprises the following steps: reacting an iron source, a titanium source, and a barium source in a solution at 135°C for 18 hours to obtain iron-doped barium titanate nanoparticles; using tetrabutyl titanate as the titanium source and barium nitrate as the barium source, dissolving them respectively in n-butanol and deionized water to obtain a precursor solution containing the titanium source and the barium source; the molar ratio of tetrabutyl titanate to barium nitrate is 1:
1.
4. The method according to claim 3, characterized in that, Iron-doped barium titanate nanoparticles are placed in deionized water and nitrogen gas is introduced. The nitrogen gas is then reduced by piezoelectric catalysis to produce ammonia or ammonium ions.