Application of ZnSnO3 nanomaterials in tribocatalytic nitrogen fixation

Abstract

This invention discloses the application of ZnSnO3 nanomaterials in tribocatalytic nitrogen fixation, belonging to the field of catalysis technology. This method utilizes frictional energy to drive nitrogen fixation and ammonia synthesis under ambient temperature and pressure. ZnSnO3 nanomaterials are mixed with a reaction solvent (water or alcohol), and electron transfer and transition occur under mechanical stirring, promoting the tribocatalytic reaction and accelerating the fixation of free nitrogen in the air. Under ambient temperature, pressure, and dark conditions, NH4+... + The generation rate can reach 219.71 μmol·L⁻¹ ‑1 ·g ‑1 ·h ‑1 After adding 10% methanol, NH4 + The generation rate can reach up to 282.46 μmol·L⁻¹. ‑1 ·g ‑1 ·h ‑1 After ball milling, ZnSnO3 nanomaterials underwent a 5-hour frictional reaction with NH4. + The generation rate reached 357.86 μmol·L⁻¹ ‑1 ·g ‑1 ·h ‑1 The yield was increased to 1.63 times that of unmilled ZnSnO3 nanomaterials, and the NH4 content was increased after introducing 10% methanol. + The generation rate was further increased to 416.02 μmol·L⁻¹. ‑1 ·g ‑1 ·h ‑1 This invention employs green catalysis technology, which is simple, low-cost, and uses environmentally friendly materials. It requires no high energy input and has potential to alleviate energy shortages and environmental pollution.

Description

Technical Field

[0001] This invention belongs to the field of catalytic nitrogen fixation technology, specifically involving the application of ZnSnO3 nanomaterials in tribocatalytic nitrogen fixation. Background Technology

[0002] With the continuous advancement of industrialization, while enjoying convenience, people also face environmental pollution and energy crises. Ammonia, as a key industrial synthetic chemical, has wide applications in chemical, agricultural, pharmaceutical, and energy storage fields. It has high energy density, is easy to store and transport, and does not produce carbon dioxide during combustion, thus it has been regarded as a highly promising green hydrogen carrier and clean fuel in recent years. The synthesis of ammonia mainly depends on the nitrogen fixation process. Nitrogen, as an important component of living matter, is an essential element for the formation of biological macromolecules such as nucleic acids and proteins. Although nitrogen (N2) accounts for about 78% of the Earth's atmosphere, its molecule contains a highly stable nonpolar covalent bond structure (N≡N, bond energy approximately 946 kJ·mol⁻¹). -1 Ammonia is difficult for organisms to directly absorb and utilize. The Haber-Bosch ammonia synthesis process, commonly used in industry, requires high temperature and pressure, resulting in high energy consumption, reliance on fossil fuels, and the release of large amounts of greenhouse gases, contradicting sustainable development goals. Therefore, developing clean, efficient, and environmentally friendly ammonia synthesis technologies is of great significance.

[0003] Against this backdrop, mechanocatalysis, which can directly convert the widely existing triboelectric energy in the environment into chemical energy, has shown great application potential. In recent years, the triboelectric effect-based mechanical energy conversion mechanism has been widely developed, capable of converting a large amount of environmental mechanical energy into electrical energy, and the charges generated by friction can further participate in redox reactions. ZnSnO3 is an important ternary composite metal oxide semiconductor material with advantages such as lead-free composition, high remanent polarization, and excellent photoelectric properties, and has been widely studied and applied in gas sensors, temperature monitors, functional material coatings, and catalysis. However, research on nitrogen fixation using ZnSnO3 for tribocatalysis has not yet been reported. Summary of the Invention

[0004] This invention aims to overcome the problems of high energy consumption and high carbon emissions in existing ammonia synthesis technologies (especially the Haber-Bosch process), as well as the technical defects of existing tribocatalytic systems in nitrogen fixation applications such as low catalytic efficiency and unclear reaction mechanism, and provides the application of ZnSnO3 nanomaterials in tribocatalytic nitrogen fixation.

[0005] Furthermore, the application is as follows: using ZnSnO3 nanomaterials as a triboelectric catalyst, dispersing ZnSnO3 nanomaterials in a reaction solvent, and achieving nitrogen fixation and ammonia synthesis under ambient temperature and pressure conditions by mechanical stirring in the dark, utilizing triboelectric catalysis, i.e., realizing the conversion of N2 to NH4. + Highly efficient conversion.

[0006] Furthermore, the ZnSnO3 nanomaterial can be either untreated raw ZnSnO3 nanomaterial or ball-milled ZnSnO3 nanomaterial. The ZnSnO3 nanomaterial is subjected to mechanochemical treatment using a high-energy planetary ball mill to reduce particle size and increase specific surface area. The ball mill speed is 200–600 rpm, the milling time is 30–120 minutes, and the ball-to-material ratio is 10:1–20:1. The preparation method of the ZnSnO3 nanomaterial is as follows: Under magnetic stirring, a 0.1-0.3 mol / L zinc sulfate aqueous solution is added dropwise to a 0.1-0.3 mol / L sodium stannate aqueous solution, controlling the molar ratio of zinc sulfate to sodium stannate to be 1:1. After the addition is complete, stirring is continued for 2-3 hours, and then the solution is allowed to stand for 10-12 hours to obtain a white precipitate. The white precipitate is washed sequentially with deionized water and anhydrous ethanol, dried at 40-60℃, and then ground to obtain the ZnSnO3 nanomaterial.

[0007] Furthermore, the reaction solvent is any one of deionized water or an aqueous methanol solution with a volume concentration of 8% to 15%.

[0008] Furthermore, the amount of ZnSnO3 nanomaterial added to the reaction solvent is 0.6–2.2 g / L.

[0009] Furthermore, the mechanical stirring speed is 600–1200 rpm, and the stirring time is 1–5 hours. The mechanical stirring uses a stir bar made of polytetrafluoroethylene (PTFE), and the shape of the stir bar can be any one of olive shape, serrated shape, or disc shape. The nitrogen fixation performance is optimized by adjusting parameters such as the amount of ZnSnO3 nanomaterial added, stirring speed, and stir bar type; the nitrogen fixation effect can be improved by adding an active species scavenger (methanol).

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0011] 1. This invention marks the first application of ZnSnO3 nanomaterials in tribocatalytic nitrogen fixation, overcoming the technical limitations of existing tribocatalytic materials in nitrogen fixation reactions, such as low efficiency and unclear mechanisms. ZnSnO3, with its ABO3-type perovskite structure, is successfully used in a mechanically driven nitrogen reduction reaction. ZnSnO3 possesses excellent physicochemical stability, a unique crystal structure, and abundant oxygen vacancies. During the tribocatalytic process, it can effectively utilize environmental mechanical energy and excite electron-hole pairs, thereby efficiently activating inert N≡N bonds. The conversion of N₂ to NH₄⁻ can be achieved even under ambient temperature, pressure, and dark conditions. + Highly efficient conversion.

[0012] 2. Compared to the industrial Haber-Bosch process (which typically requires 300–500°C and 15–25 MPa), this invention operates entirely under ambient temperature and pressure conditions. It only requires a conventional mechanical stirring device to provide driving frictional energy (e.g., 1000 rpm), eliminating the need for any light source, heat source, high-pressure equipment, or external electric field. It does not consume fossil fuels and emits no greenhouse gases, achieving truly green and low-energy ammonia synthesis. After adding 10 vol% methanol as a hole scavenger, NH4... + The yield can be further improved, and the reaction can still be carried out under dark conditions, breaking through the limitation of photocatalysis being dependent on light.

[0013] 3. This invention employs a one-step aqueous solution method to prepare ZnSnO3 nanomaterials. The process is short, simple, and low-cost, requiring no complex equipment or stringent reaction conditions. Nitrogen fixation performance can be easily optimized by systematically controlling key parameters such as catalyst dosage, stirring speed, and stir bar type. Furthermore, ball milling of the ZnSnO3 nanomaterials significantly enhances its catalytic activity, particularly for NH4+. + The yield is significantly improved. The material itself is environmentally friendly and has good cycle stability, providing a feasible solution for developing new, efficient, and low-cost mechanical energy-driven ammonia synthesis technology, which is expected to alleviate energy shortages and environmental pollution problems. Attached Figure Description

[0014] Figure 1 This is a graph showing the nitrogen fixation yield of ZnSnO3 nanomaterials with different addition amounts in Example 1.

[0015] Figure 2 This is a graph showing the nitrogen fixation yield at different rotation speeds in Example 1.

[0016] Figure 3 This is a graph showing the nitrogen fixation yield of different stirrers in Example 1.

[0017] Figure 4 This is a graph showing the nitrogen fixation yield with different sacrificial agents added in Example 2.

[0018] Figure 5These are XRD patterns of ZnSnO3 nanomaterials ball-milled for different times in Example 3.

[0019] Figure 6 This is a graph showing the nitrogen fixation yield of ZnSnO3 nanomaterials treated with ball milling for different times in Example 3.

[0020] Figure 7 This is a graph showing the nitrogen fixation yield with different sacrificial agents added in Example 4. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the following examples, the ZnSnO3 nanomaterials were prepared as follows: Under magnetic stirring, 20 mL of 0.15 mol / L zinc sulfate aqueous solution was added dropwise to 20 mL of 0.15 mol / L sodium stannate aqueous solution. After the addition was complete, stirring was continued for 2 h. The solution was then allowed to stand for 12 h to obtain a white precipitate. The white precipitate was washed sequentially with deionized water and anhydrous ethanol, dried at 50 °C, and then ground to obtain ZnSnO3 nanomaterials.

[0023] Example 1: Tribocatalytic nitrogen fixation in a deionized water system

[0024] Different weights (30 mg, 50 mg, 70 mg, 90 mg, 110 mg) of ZnSnO3 nanomaterials were weighed and dispersed in 50 mL of deionized water. The reaction mixture was stirred continuously at 1000 rpm for 5 hours in a dark environment with normal temperature and pressure using a PTFE rotating stirrer. NH4+ + Production Figure 1 As shown, the optimal dosage of ZnSnO3 nanomaterials is 70 mg (i.e., 1.4 g / L). Then, with the ZnSnO3 nanomaterial dosage fixed at 70 mg, the effect of stir bar speed (400 rpm, 600 rpm, 800 rpm, 1000 rpm, 1200 rpm) on the nitrogen fixation effect was investigated. It is clear that 1000 rpm is the best. Figure 2 Finally, under the conditions of 70 mg ZnSnO3 nanomaterials and a stirrer speed of 1000 rpm, the effects of different stirrers (olive-1 with a length of 20 mm, olive-2 with a length of 35 mm, serrated stirrer with a diameter of 35 mm, and disk stirrer with a diameter of 35 mm) on the nitrogen fixation effect were investigated. It was found that the PTFE disk triboelectric catalytic nitrogen fixation rate was the highest. Figure 3 As shown in the diagram, during the reaction, the ZnSnO3 nanomaterials undergo a tribocatalytic effect under the shear force generated by the stir bar and the frictional force generated by interparticle collisions, reducing dissolved N2 molecules to NH4. + The conclusion is that the nitrogen fixation efficiency is highest under the conditions of 70 mg (1.4 g / L) ZnSnO3 nanomaterials and a PTFE disc stirrer speed of 1000 rpm, and NH4+. + The generation rate reached 219.71 μmol·L⁻¹ -1 ·g -1 ·h -1 .

[0025] Example 2: Tribocatalytic nitrogen fixation under different sacrificial agents

[0026] 70 mg of ZnSnO3 nanomaterials were weighed and dispersed in 50 mL of reaction solvent (deionized water, 10 vol% methanol aqueous solution, and 0.02 mol / L KBrO3 aqueous solution). The reaction was carried out using a PTFE stirring disc at 1000 rpm for 5 h in a dark environment at room temperature and pressure. Methanol, acting as a hole sacrificial agent, effectively captures photogenerated holes generated by the triboelectric excitation of ZnSnO3 nanomaterials, inhibits electron-hole recombination, and improves electron utilization for N2 reduction. KBrO3, on the other hand, acts as an electron sacrificial agent, leading to the reduction of NH4+. + Production declined. For example... Figure 4 As shown, after adding 10% methanol, NH4 + The generation rate can reach 282.46 μmol·L⁻¹ -1 ·g -1 ·h -1 .

[0027] Example 3: Ball milling treatment of ZnSnO3 nanomaterials for tribocatalytic nitrogen fixation

[0028] 1.0 g of ZnSnO3 nanomaterial was weighed and placed in the grinding jar of a high-energy planetary ball mill along with 20.0 g of zirconia grinding balls (ball-to-material ratio 20:1). The ball mill speed was set to 600 rpm, and the grinding time was set to different values ​​(30 min, 60 min, 90 min, and 120 min). The XRD pattern of the sample after ball milling is shown below. Figure 5 As shown, the diffraction peaks of the sample broaden continuously with increasing ball milling time, which is related to the continuous decrease in grain size of the sample with the accumulation of ball milling time. Then, 70 mg of ball-milled ZnSnO3 nanomaterials were weighed and dispersed in 50 mL of deionized water. A PTFE rotating stirrer was used, and the reaction was continuously stirred at 1000 rpm for 5 h in a dark environment at room temperature and pressure. It can be concluded that the frictional catalytic nitrogen fixation effect is best when ball milling is performed for 60 min. Figure 6 As shown.

[0029] Example 4: Ball milling of ZnSnO3 nanomaterials for tribocatalytic nitrogen fixation under different sacrificial agents

[0030] Weigh 1.0 g of ZnSnO3 nanomaterial and place it in the grinding jar of a high-energy planetary ball mill along with 20.0 g of zirconia grinding balls (ball-to-material ratio 20:1). Set the ball mill speed to 600 rpm and mill for 60 min. Then weigh 70 mg of the milled ZnSnO3 nanomaterial (denoted as ZSO-60) and disperse it in 50 mL of reaction solvent (deionized water, 10 vol% methanol aqueous solution, 0.02 mol / L KBrO3 aqueous solution). Use a PTFE rotating stirrer and continuously stir at 1000 rpm for 5 h in a dark environment at room temperature and pressure. The same experimental conclusion as in Example 2 can be drawn, that is, after adding 10% methanol, NH4... + The generation rate can reach 416.02 μmol·L⁻¹ -1 ·g -1 ·h -1 .

Claims

1. Application of ZnSnO3 nanomaterials in tribocatalytic nitrogen fixation.

2. The application of ZnSnO3 nanomaterial in catalytic nitrogen fixation by friction according to claim 1, characterized in that: Before use, the ZnSnO3 nanomaterials are ball-milled using a high-energy planetary ball mill.

3. The application of ZnSnO3 nanomaterial in catalytic nitrogen fixation by friction according to claim 2, characterized in that: The parameters for the ball milling process are: ball mill speed of 200-600 rpm, ball milling time of 30-120 minutes, and ball-to-material ratio of 10:1-20:

1.

4. The application of ZnSnO3 nanomaterial in catalytic nitrogen fixation by friction according to claim 1 or 2, characterized in that: The preparation method of the ZnSnO3 nanomaterial is as follows: Under magnetic stirring, a 0.1-0.3 mol / L zinc sulfate aqueous solution is added dropwise to a 0.1-0.3 mol / L sodium stannate aqueous solution, controlling the molar ratio of zinc sulfate to sodium stannate to be 1:

1. After the addition is complete, stirring is continued for 2-3 hours, and then the solution is allowed to stand for 10-12 hours to obtain a white precipitate. The white precipitate is washed sequentially with deionized water and anhydrous ethanol, dried at 40-60℃, and then ground to obtain the ZnSnO3 nanomaterial.

5. The use of ZnSnO3 nanomaterials according to any one of claims 1 to 3 in the catalytic fixation of nitrogen by rubbing, characterized in that: ZnSnO3 nanomaterials were dispersed in a reaction solvent, and nitrogen was fixed and ammonia was synthesized by frictional catalysis under ambient temperature and pressure by mechanical stirring in the dark.

6. The use of ZnSnO3 nanomaterials in catalytic nitrogen fixation by friction according to claim 5, characterized in that: The reaction solvent is any one of deionized water or an aqueous methanol solution with a volume concentration of 8% to 15%.

7. The use of ZnSnO3 nanomaterials in catalytic nitrogen fixation by friction according to claim 5, characterized in that: The amount of ZnSnO3 nanomaterial added to the reaction solvent is 0.6–2.2 g / L.

8. The use of ZnSnO3 nanomaterials in catalytic nitrogen fixation by friction according to claim 5, characterized by the fact that: The mechanical stirring speed is 600-1200 rpm, and the stirring time is 5-10 hours.

9. The use of ZnSnO3 nanomaterials in catalytic nitrogen fixation by friction according to claim 5, characterized in that: The mechanical stirring uses a stir bar made of polytetrafluoroethylene, and the shape of the stir bar can be any one of olive shape, serrated shape, or turntable shape.

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