A method for preparing hydrogen peroxide based on triazine-based photocatalyst and mixed solvent
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-24
- Publication Date
- 2026-08-14
AI Technical Summary
[0004]在反应介质与产物分离方面，当前单相溶剂体系面临双重困境：其一，单相溶剂（无论纯水或有机溶剂）介电环境单一，缺乏界面极化场，无法为光生电子-空穴对提供额外分离驱动力，载流子复合严重，量子效率偏低；其二，均相体系内产物与溶剂完全互溶，下游分离纯化需依赖蒸馏、萃取等高能耗单元操作，工艺复杂度与成本显著增加
[0015]混合溶剂界面极化效应显著促进光催化剂电荷分离，过氧化氢生成速率较传统单相溶剂体系提高3~6倍以上；利用相分配特性实现产物便捷低能耗分离，分离过程仅需简单分液操作；在300~1000 nm宽光谱范围内均保持高效催化活性；催化剂经多次循环使用性能无衰减，放大规模下仍稳定运行；混合溶剂可回收循环使用，工艺绿色、成本低。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of photocatalytic synthesis technology, specifically relating to a highly efficient photocatalytic oxygen reduction method for preparing hydrogen peroxide based on the synergistic effect of a triazine-based photocatalyst and a mixed solvent. Background Technology
[0002] H2O2, as a green oxidant whose decomposition products are only water and oxygen, has wide applications in chemical synthesis, environmental remediation, and disinfection. It also possesses the potential to be a clean energy carrier as a high-energy-density liquid fuel, with global annual production exceeding several million tons and demand continuing to grow. The traditional anthraquinone process suffers from inherent drawbacks such as lengthy processes, high energy consumption, hydrogen safety hazards, and the risk of product decomposition and explosion during storage and transportation, severely restricting distributed applications. Solar-driven photocatalytic oxygen reduction reaction for in-situ synthesis of H2O2, utilizing water, oxygen, and sunlight under mild conditions for distributed, on-demand production, represents an ideal green pathway to avoid storage and transportation risks. However, its practical application still faces multiple scientific challenges. This reaction involves a two-step single-electron or one-step two-electron reduction pathway, requiring catalysts with suitable band structures, efficient charge separation capabilities, and selective two-electron reduction active sites. Sufficient proton supply and effective side reaction suppression are also necessary to ensure high selectivity.
[0003] In the field of photocatalysts, existing materials generally suffer from the core bottleneck of low charge separation efficiency. Inorganic semiconductors such as TiO2 exhibit severe recombination of photogenerated electron-hole pairs; metal-organic frameworks, while structurally tunable, suffer from limited carrier mobility; graphitic carbon nitride exhibits poor charge delocalization, high exciton binding energy, and difficulty in carrier separation; and carbon-based materials, being single components, struggle to establish an effective built-in electric field. In summary, enhancing the efficient separation and transport of photogenerated carriers is crucial for improving the efficiency of photocatalytic H2O2 production.
[0004] In terms of separating reaction media from products, current single-phase solvent systems face a dual dilemma: First, single-phase solvents (whether pure water or organic solvents) have a single dielectric environment and lack an interfacial polarization field, which cannot provide additional separation driving force for photogenerated electron-hole pairs, resulting in severe carrier recombination and low quantum efficiency; Second, in homogeneous systems, products and solvents are completely miscible, and downstream separation and purification require high-energy-consuming unit operations such as distillation and extraction, which significantly increases process complexity and cost. Summary of the Invention
[0005] To address the problem of how to simultaneously achieve efficient charge separation and convenient product separation in the same system, this invention provides a method for preparing hydrogen peroxide by efficient photocatalytic oxygen reduction based on the synergistic effect of a triazine-based photocatalyst and a mixed solvent.
[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0007] A method for preparing hydrogen peroxide based on a synergistic photocatalytic reaction system is disclosed. A triazine-rich organic photocatalyst is uniformly dispersed in a mixed solvent containing water and ester / alkane organic solvents to construct a synergistic photocatalytic reaction system. The significant difference in dielectric constant and dipole moment gradient at the interface between the aqueous and organic phases in the mixed solvent creates an interfacial polarization field at the catalyst-solution interface. This field provides a directional separation driving force for the photogenerated electron-hole pairs of the triazine-rich organic photocatalyst, promoting charge separation and suppressing carrier recombination, thereby improving the photocatalytic yield. Under visible light irradiation, oxygen or air is introduced into the photocatalytic reaction system to carry out a photocatalytic oxygen reduction reaction, generating hydrogen peroxide. After the reaction, due to the immiscibility between water and the ester / alkane organic solvents, the system naturally separates into phases. Hydrogen peroxide is selectively enriched in the aqueous phase due to its strong polarity, while the catalyst is dispersed in the organic phase or at the interface between the two phases. The product and the catalytic system can be separated with low energy consumption through simple liquid-liquid separation, and the catalyst can be directly recovered and recycled.
[0008] Furthermore, the mixed solvent is a mixture of water and ester / alkane organic solvents in a volume ratio of 9~16:2~5.
[0009] Furthermore, the ester / alkane organic solvent is selected from one of the following that are immiscible with water: n-pentane, cyclohexane, n-hexane, n-heptane, isobutanol, n-butanol, n-pentanol, xylene, ethyl acetate, propyl propionate, butyl butyrate, hexadecane, dodecane, and tetradecane.
[0010] Furthermore, the triazine-rich organic photocatalyst is a triazine-like organic molecule or its polymer containing a triazine ring structure.
[0011] Furthermore, the triazine-rich organic photocatalyst is selected from one of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine, trimercaptotriazine, 1,3,5-trimethylhexahydro-1,3,5-triazine, or triazine triol.
[0012] Furthermore, the amount of the triazine-rich organic photocatalyst used is 0.1–6 g / L, preferably 1–3 g / L.
[0013] Furthermore, the temperature for the photocatalytic oxygen reduction reaction is 10–100 °C, and the visible light intensity is 100–500 mW / cm². 2 The time range is 0.5 to 24 hours, and the spectral range is 300 to 1000 nm.
[0014] Compared with the prior art, the present invention has the following advantages:
[0015] The interfacial polarization effect of the mixed solvent significantly promotes charge separation of the photocatalyst, increasing the hydrogen peroxide generation rate by 3 to 6 times compared to traditional single-phase solvent systems. The phase distribution characteristics enable convenient and low-energy separation of products, requiring only simple liquid-liquid separation. It maintains high catalytic activity across a wide spectral range of 300–1000 nm. The catalyst exhibits no performance degradation after multiple cycles and remains stable even at scale-up. The mixed solvent is recyclable, making the process green and low-cost. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 Comparison of the UV-Vis diffuse reflectance spectra of the triazine photocatalyst in Example 4 and Comparative Example 2 in mixed solvent and single-phase solvent shows the broadening of the light absorption range in the mixed solvent system.
[0018] Figure 2 The time-resolved fluorescence decay curves of the triazine photocatalyst in Example 1 and Comparative Example 1 in different solvent systems characterize the separation efficiency and lifetime extension of photogenerated electron-hole pairs in the mixed solvent system.
[0019] Figure 3 Comparison of theoretical simulation calculations of dipole moments for water as a single solvent, propyl propionate as a single organic solvent, and a mixture of the two.
[0020] Figure 4 Comparison of H2O2 generation rates between the mixed solvent system and the traditional single-phase solvent system in Example 1 and Comparative Example 1.
[0021] Figure 5 Example 1: Activity stability test diagram of the scaled-up system during 15 cycles of use.
[0022] Figure 6 Schematic diagram of natural separation of water-organic two phases and product separation after reaction. Detailed Implementation
[0023] To gain a deeper understanding of this invention, we will provide a comprehensive and detailed description. However, this invention has various implementations and is not limited to the specific examples listed herein. These examples are presented to enhance a full understanding of the disclosure of this invention.
[0024] In each embodiment, 1% isopropanol was added as a hole scavenger, which is much lower than the bulk volume of water and organic solvent in the mixed solvent, and its effect on the solvent effect of the mixed solvent is negligible.
[0025] Example 1:
[0026] A mixed solvent was prepared by mixing water and dodecane at a volume ratio of 11:4. 2,4,6-Tris(4-carboxyphenyl)-1,3,5-triazine photocatalyst was added to the mixed solvent at a dosage of 1 g / L and ultrasonically dispersed for 5 minutes to obtain a photocatalytic reaction suspension. The suspension was transferred to a photocatalytic reactor and heated to 25°C under visible light irradiation (light intensity 120 mW / cm²). 2 Oxygen or air was continuously introduced into the system (spectral range 300~1000 nm) and the reaction was carried out for 1 h. After the reaction was completed, the light and air were stopped, and the system was allowed to stand for 5 minutes to allow the layers to separate. The lower aqueous phase was collected by liquid separation to obtain the H2O2 product, while the upper organic phase and the contained catalyst were recovered and recycled for the next batch of reaction.
[0027] The reaction system was further scaled up 350 times to 5.2 L, using the same mixed solvent ratio and catalyst dosage, and the photocatalytic reaction was carried out at a 350-fold volume scale under the same reaction conditions. Testing showed that the hydrogen peroxide generation rate remained stable over 15 cycles after scale-up, with good phase separation, convenient product separation, and no significant degradation in the recycling performance of the catalyst and organic phase, indicating that the system has excellent scale-up adaptability.
[0028] Example 2:
[0029] A mixed solvent was prepared by mixing water and cyclohexane at a volume ratio of 10:3. 2,4,6-Tris(4-carboxyphenyl)-1,3,5-triazine photocatalyst was added to the mixed solvent at a dosage of 1.0 g / L, and the mixture was stirred and dispersed for 10 minutes to obtain a photocatalytic reaction suspension. The suspension was transferred to a photocatalytic reactor, and the temperature was controlled at 30°C. Oxygen or air was continuously introduced under visible light irradiation (light intensity 150 mW / cm², spectral range 300–700 nm) for 1 h. After the reaction, the irradiation and aeration were stopped, and the system was allowed to naturally separate into layers. The lower aqueous phase was collected by liquid separation to obtain H₂O₂ product, while the upper organic phase and catalyst were recycled.
[0030] Example 3:
[0031] A mixed solvent was prepared by mixing water and n-hexane at a volume ratio of 9:2. The 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine organic polymer photocatalyst was added to the mixed solvent at a dosage of 1.5 g / L and ultrasonically dispersed for 7 minutes to obtain a photocatalytic reaction suspension. The suspension was transferred to a photocatalytic reactor and heated to 30°C under visible light irradiation (light intensity 150 mW / cm²). 2 Oxygen or air was continuously introduced into the atmosphere (spectral range 390~630 nm) and the reaction was carried out for 1 h. After the reaction was completed, the light and air were stopped, and the mixture was allowed to stand and separate into layers. The aqueous phase was collected by liquid-liquid extraction to obtain the H2O2 product, while the organic phase and catalyst were recycled.
[0032] Example 4:
[0033] A mixed solvent was prepared by mixing propyl propionate and water at a volume ratio of 2:7. Trithiomercaptotriazine photocatalyst was added to the mixed solvent at a dosage of 0.9 g / L, and the mixture was ultrasonically dispersed for 6 minutes to obtain a photocatalytic reaction suspension. The suspension was transferred to a photocatalytic reactor and heated to 25°C under visible light irradiation (light intensity 100 mW / cm²). 2 Oxygen or air was continuously introduced into the atmosphere (spectral range 350~630 nm) and the reaction was allowed to proceed for 1 h. After the reaction was completed, the light and air were stopped, and the mixture was allowed to stand and separate into layers. The aqueous phase was collected by liquid-liquid extraction to obtain the H2O2 product, while the organic phase and catalyst were recycled.
[0034] Example 5:
[0035] A mixed solvent was prepared by mixing water and n-heptane at a volume ratio of 13:4. 1,3,5-Trimethylhexahydro-1,3,5-triazine photocatalyst was added to the mixed solvent at a dosage of 1.0 g / L, and the mixture was stirred and dispersed for 10 minutes to obtain a photocatalytic reaction suspension. The suspension was transferred to a photocatalytic reactor and heated to 30°C under visible light irradiation (light intensity 250 mW / cm²). 2 Oxygen or air was continuously introduced into the atmosphere (spectral range 300~630 nm) and the reaction was allowed to proceed for 1 h. After the reaction was completed, the light and air were stopped, and the mixture was allowed to stand and separate into layers. The aqueous phase was collected by liquid-liquid extraction to obtain the H2O2 product, while the organic phase and catalyst were recycled.
[0036] Example 6:
[0037] Hexadecane and water were mixed at a volume ratio of 3:10 to prepare a mixed solvent. 1,3,5-Trimethylhexahydro-1,3,5-triazine photocatalyst was added to the mixed solvent at a dosage of 2.0 g / L and ultrasonically dispersed for 15 minutes to obtain a photocatalytic reaction suspension. The suspension was transferred to a photocatalytic reactor and heated to 25°C under visible light irradiation (light intensity 150 mW / cm²). 2Oxygen or air was continuously introduced (spectral range 300~1000 nm) and the reaction was carried out for 2 h. After the reaction was completed, the light and air were stopped, and the mixture was allowed to stand and separate into layers. The lower aqueous phase was collected by liquid-liquid separation to obtain H2O2 product, while the upper organic phase and catalyst were recovered and directly recycled for the next batch of reaction.
[0038] Example 7:
[0039] A mixed solvent was prepared by mixing water and butyl butyrate at a volume ratio of 8:2.5. The triazine triol organic polymer photocatalyst was added to the mixed solvent at a dosage of 0.5 g / L, and the mixture was ultrasonically dispersed for 10 minutes to obtain a photocatalytic reaction suspension. The suspension was transferred to a photocatalytic reactor and heated to 25°C under visible light irradiation (light intensity 120 mW / cm²). 2 Oxygen or air was continuously introduced into the system (spectral range 390~630 nm) and the reaction was carried out for 1 h. After the reaction was completed, the light and air were stopped, and the system was allowed to stand to separate into layers. The aqueous phase was collected by liquid-liquid extraction to obtain the H2O2 product, while the organic phase and catalyst were recycled.
[0040] Example 8:
[0041] A mixed solvent was prepared by mixing water and tetradecane at a volume ratio of 10:4. The triazine triol photocatalyst was added to the mixed solvent at a dosage of 1.0 g / L, and the mixture was stirred and dispersed for 15 minutes to obtain a photocatalytic reaction suspension. The suspension was transferred to a photocatalytic reactor and heated to 30°C under visible light irradiation (light intensity 180 mW / cm²). 2 Oxygen or air was continuously introduced into the atmosphere (spectral range 390~630 nm) and the reaction was carried out for 1 h. After the reaction was completed, the light and air were stopped, and the mixture was allowed to stand and separate into layers. The aqueous phase was collected by liquid-liquid extraction to obtain the H2O2 product, while the organic phase and catalyst were recycled.
[0042] Comparative Example 1:
[0043] The same 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine photocatalyst and reaction conditions as in Example 1 were used, the difference being that dodecane and water were used instead of the mixed solvent, respectively. Detection showed that the H2O2 formation rate was only 1 / 6 that of Example 1, and the products could not be separated by simple liquid-liquid separation.
[0044] Comparative Example 2:
[0045] The same trithiotriazine photocatalyst and reaction conditions as in Example 4 were used, except that pure propyl propionate was used instead of the mixed solvent.
[0046] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.
Claims
1. A method for preparing hydrogen peroxide based on a synergistic photocatalytic reaction system, characterized in that, A triazine-rich organic photocatalyst is uniformly dispersed in a mixed solvent containing water and ester / alkane organic solvents to construct a synergistic photocatalytic reaction system. The significant difference in dielectric constant and dipole moment gradient at the interface between the aqueous and organic phases in the mixed solvent creates an interfacial polarization field at the catalyst-solution interface. This field provides a directional separation driving force for the photogenerated electron-hole pairs of the triazine-rich organic photocatalyst, promoting charge separation and inhibiting carrier recombination, thereby improving the photocatalytic yield. Under visible light irradiation, oxygen or air is introduced into the photocatalytic reaction system to carry out a photocatalytic oxygen reduction reaction, generating hydrogen peroxide. After the reaction, due to the immiscibility between water and the ester / alkane organic solvents, the system naturally separates into phases. Hydrogen peroxide, due to its strong polarity, selectively accumulates in the aqueous phase, while the catalyst is dispersed in the organic phase or at the interface between the two phases. Low-energy separation of the product from the catalytic system can be achieved through simple liquid-liquid separation, allowing the catalyst to be directly recovered and recycled.
2. The method for preparing hydrogen peroxide based on a synergistic photocatalytic reaction system according to claim 1, characterized in that, The mixed solvent is a mixture of water and ester / alkane organic solvents in a volume ratio of 9~16:2~5.
3. The method for preparing hydrogen peroxide based on a synergistic photocatalytic reaction system according to claim 1, characterized in that, The ester / alkane organic solvent is selected from one of the following that are immiscible with water: n-pentane, cyclohexane, n-hexane, n-heptane, isobutanol, n-butanol, n-pentanol, xylene, ethyl acetate, propyl propionate, butyl butyrate, hexadecane, dodecane, and tetradecane.
4. The method for preparing hydrogen peroxide based on a synergistic photocatalytic reaction system according to claim 1, characterized in that, The triazine-rich organic photocatalyst is a triazine-like organic molecule or its polymer containing a triazine ring structure.
5. The method for preparing hydrogen peroxide based on a synergistic photocatalytic reaction system according to claim 4, characterized in that, The triazine-rich organic photocatalyst is selected from one of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine, trimercaptotriazine, 1,3,5-trimethylhexahydro-1,3,5-triazine, or triazine triol.
6. The method for preparing hydrogen peroxide based on a synergistic photocatalytic reaction system according to claim 1, characterized in that, The amount of the triazine-rich organic photocatalyst used is 0.1–6 g / L.
7. The method for preparing hydrogen peroxide based on a synergistic photocatalytic reaction system according to claim 1, characterized in that, The temperature range for photocatalytic oxygen reduction reaction is 10–100℃, and the visible light intensity is 100–500 mW / cm². 2 The time range is 0.5 to 24 hours, and the spectral range is 300 to 1000 nm.