Method for generating hydrogen peroxide based on Malangori bursting

Abstract

The invention discloses a method for generating hydrogen peroxide based on Malangori bursting, and relates to the technical field of chemical engineering and interface science. The method comprises the following steps: heating an organic reagent which is immiscible with water to 30-60 DEG C, mixing an aqueous solution containing a volatile organic solvent with the organic reagent which is immiscible with water in a dripping manner, inducing liquid drops to burst to generate micro-liquid drops through a Malangei effect of an oil-water interface, and then carrying out oil-water separation to obtain hydrogen peroxide in a water phase. Liquid drops are driven to burst by utilizing the Malangori effect at an oil-water interface, a large number of micro-liquid drops with high specific surface area are generated, and the interface reaction area and the material transfer efficiency are remarkably improved, so that efficient and green preparation of hydrogen peroxide is realized; the defects of an existing industrial anthraquinone method and a photocatalysis method in the aspects of environmental friendliness, reaction efficiency and system simplification are overcome.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering and interface science and technology, and in particular to a method for generating hydrogen peroxide based on Marangoni explosion. Background Art

[0002] Hydrogen peroxide (H2O2), also known as hydrogen peroxide, is an important green oxidant widely used in the chemical, environmental, pharmaceutical, and electronics industries. Currently, the anthraquinone method is the primary method used in industry to produce hydrogen peroxide. This method, however, is complex, energy-intensive, and poses significant challenges, including high equipment investment and environmental impact. Therefore, developing new, green, efficient, and energy-efficient methods for producing hydrogen peroxide has become a research hotspot.

[0003] Photocatalytic generation of hydrogen peroxide has always been a hot research topic. The photocatalytic generation of hydrogen peroxide usually uses semiconductor photocatalysts (such as TiO2, g-C3N4, BiVO4, etc.) to generate electron-hole pairs under ultraviolet or visible light irradiation. The excited electrons migrate to the catalyst surface and undergo a two-electron reduction reaction (O2+2H + +2e - →H2O2), generating hydrogen peroxide. This method has mild reaction conditions and can be carried out at room temperature and pressure, without organic solvents or additives, making it environmentally friendly and sustainable. Furthermore, some studies have further improved the activity and selectivity of photocatalysts by loading precious metals, constructing heterojunctions, or surface modification. Although this method has been demonstrated in the laboratory for the photocatalytic generation of H2O2 using a variety of photocatalyst systems, its practical application still faces numerous challenges and limitations:

[0004] (1) Low yield and concentration

[0005] The photocatalytic method usually produces hydrogen peroxide through an oxygen reduction reaction in the aqueous phase. However, due to the complex reaction pathway and the easy further reduction or decomposition of hydrogen peroxide, the actual generated concentration is generally low, which is difficult to meet industrial needs.

[0006] (2) Poor stability of photocatalyst

[0007] Commonly used photocatalysts (such as TiO2, g-C3N4, BiVO4, Au / TiO2) are prone to photocorrosion and activity decay under long-term irradiation or the presence of high-concentration hydrogen peroxide, resulting in a decrease in catalytic efficiency and affecting long-term operation.

[0008] (3) Selectivity issues

[0009] During the photocatalytic process, O2 molecules can undergo two-electron reduction to generate H2O2 or four-electron reduction to generate water.- The pathway selectivity is limited, and by-products are easily generated, which reduces the H2O2 yield.

[0010] (4) Slow reaction kinetics

[0011] The reaction kinetics of photocatalytic reduction of O2 is relatively slow, especially in the absence of precious metals or plasma-assisted systems, where the electron-hole recombination rate is fast and the proportion of effective electrons used to reduce O2 is low.

[0012] (5) Difficulty in equipment scaling up

[0013] Laboratory photocatalytic reactors are easy to operate, but in industrial scale-up, they are restricted by factors such as light source intensity, light penetration depth, catalyst dispersion, and temperature control, making it difficult to ensure that efficient reactions can be maintained after scale-up.

[0014] (6) Energy consumption

[0015] Although clean energy such as sunlight can be used, most existing systems rely on ultraviolet or visible light LEDs, which have low actual light energy utilization efficiency and a mismatch between energy consumption and product value.

[0016] Therefore, it is particularly urgent to provide a new synthesis method that does not require a catalyst, is environmentally friendly, and can efficiently produce hydrogen peroxide to solve the problems of low reaction efficiency and high energy consumption in the preparation of hydrogen peroxide in the existing technology. Summary of the Invention

[0017] The purpose of the present invention is to provide a method for generating hydrogen peroxide based on Marangoni explosion to solve the problems existing in the above-mentioned prior art.

[0018] To achieve the above object, the present invention provides the following solutions:

[0019] The present invention provides a method for generating hydrogen peroxide based on Marangoni burst-driven micro-droplet interface, comprising the following steps:

[0020] The water-immiscible organic reagent is heated to 30-60° C., and an aqueous solution containing a volatile organic solvent is added dropwise to the water-immiscible organic reagent, and the droplets are induced to burst to form microdroplets through the Marangoni effect at the oil-water interface, thereby separating the oil phase and the aqueous phase to obtain hydrogen peroxide in the aqueous phase.

[0021] Moreover, the diffusion coefficient S>0 is required;

[0022] S=γ oa -γ ma -γ mo ; Among them, γ oa is the interfacial tension between the water-immiscible organic reagent and air, γ mais the interfacial tension between the aqueous solution containing volatile organic solvents and air, γ mo It is the interfacial tension between an aqueous solution containing a volatile organic solvent and a water-immiscible organic reagent.

[0023] As a further preferred embodiment of the present invention, the water-immiscible organic agent includes vegetable oil; the vegetable oil includes sunflower oil, castor oil or peanut oil.

[0024] As a further preferred embodiment of the present invention, the volatile organic solvent is a ketone or an alcohol. Furthermore, the ketone includes acetone; and the alcohol includes isopropyl alcohol or ethanol.

[0025] As a further preferred embodiment of the present invention, the next drop of the aqueous solution containing the volatile organic solvent is added after the inner diameter of the previous drop of the aqueous solution containing the volatile organic solvent shrinks.

[0026] As a further preferred embodiment of the present invention, the dripping speed is 40-80 μL / min; more preferably 60 μL / min.

[0027] As a further preferred embodiment of the present invention, the volatile organic solvent is isopropyl alcohol.

[0028] As a further preferred embodiment of the present invention, the aqueous solution containing a volatile organic solvent is an isopropyl alcohol aqueous solution having an isopropyl alcohol volume concentration of 40-80%; more preferably, the isopropyl alcohol volume concentration is 60%.

[0029] In the present invention, the chemical reaction mechanism of hydrogen peroxide generation is as follows:

[0030] There is a strong electric field (~10 9 V / m);

[0031] Hydroxyl radical (·OH) formation: H2O→·OH+H + +e - , ·OH+·OH→H2O2;

[0032] Superoxide radicals (·O2 - ) Formation: dissolved O2 gains electrons at the interface to generate O2 - , further with H + The reaction produces H2O2: O2 + e - → O2 - +H + →HO2·+e - +H + →H2O2.

[0033] The present invention directly promotes the reaction through physical effects, has a fast reaction rate, and the entire explosion process to produce microdroplets only takes a few seconds, and avoids the problems of poor catalyst stability and low selectivity in the photocatalytic method; at the same time, the present invention uses physical energy to drive the interfacial reaction, which has lower energy consumption.

[0034] Marangoni flow is direction-dependent, and the flow direction is determined by the direction of the interfacial tension gradient:

[0035] When a droplet spreads on the oil surface, it becomes thicker in the middle and thinner at the edges. The alcohol at the edges evaporates more easily, increasing interfacial tension. This causes Plateau-Rayleigh instability, resulting in the formation of microdroplets that move radially outward. When the bursting phase ends, the microdroplets slowly shrink toward the center due to the thermal Marangoni effect.

[0036] The method of the invention does not require a catalyst or a light source, can generate hydrogen peroxide at a high concentration under normal pressure conditions.

[0037] The present invention monitors the concentration of hydrogen peroxide in the aqueous phase by a potassium titanium oxalate titration method.

[0038] The present invention relates to a method for preparing hydrogen peroxide based on Marangoni explosion, which utilizes the Marangoni flow at the oil-water interface to drive droplet splitting and form a micro-droplet system with a high specific surface area, thereby promoting interfacial reaction to achieve spontaneous and efficient generation of hydrogen peroxide.

[0039] In the hydrogen peroxide generation method based on Marangoni explosion of the present invention:

[0040] Organic reagents that are immiscible with water are used to construct the oil interface, providing a physical place for the Marangoni effect. The droplets are driven to burst through the interfacial tension gradient. They do not vaporize or react chemically themselves and are reusable.

[0041] In the Marangoni-based hydrogen peroxide generation method, the entire reaction takes place in a liquid environment. A water-immiscible organic reagent is in liquid form, serving as the underlying medium. An aqueous solution containing a volatile organic solvent is dripped onto the surface of the water-immiscible organic reagent in the form of droplets, forming an oil-water interface. The Marangoni effect induces the aqueous droplets to burst into liquid microdroplets, increasing the interfacial area and promoting the reaction to produce liquid hydrogen peroxide. In the reaction system, the volatile organic solvent is the only gaseous component; its role is to create an interfacial tension gradient through volatilization, driving the formation of microdroplets.

[0042] The present invention discloses the following technical effects:

[0043] The present invention prepares hydrogen peroxide based on Marangoni burst-driven micro-droplet interface, which can achieve efficient generation and convenient collection of hydrogen peroxide under catalyst-free and light-free conditions, and is both economical and environmentally friendly.

[0044] Compared to the complex extraction process of the industrial anthraquinone method, the present invention can directly collect the aqueous phase by utilizing phase separation characteristics, significantly simplifying the operation. By condensing and recovering the volatile organic solvent, solvent consumption can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 Schematic diagram of a device for generating hydrogen peroxide at a micro-droplet interface based on Marangoni burst driving according to Example 1 of the present invention.

[0047] Figure 2 Graph showing the relationship between the concentration of the isopropyl alcohol-water solution used in Example 1 of the present invention and the concentration of generated hydrogen peroxide.

[0048] Figure 3 This is a top view of the droplet bursting process during the preparation of hydrogen peroxide in Example 1 of the present invention.

[0049] Figure 4 This is an optical microscope image of the droplet bursting process during the preparation of hydrogen peroxide in Example 1 of the present invention.

[0050] Figure 5 The concentration of hydrogen peroxide generated in Examples 2 and 3 of the present invention (measured after 8 minutes of dripping) DETAILED DESCRIPTION

[0051] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0052] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0053] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0054] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0055] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0056] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.

[0057] Currently, hydrogen peroxide is primarily produced industrially using the anthraquinone process. While this method is mature and boasts high production capacity, it suffers from complex processes, high equipment investment, high energy consumption, and environmental pollution from organic solvents and byproducts, making it difficult to meet the demands of green and low-carbon industrial development. Meanwhile, the recently emerging photocatalytic method, while offering advantages such as mild reaction conditions and the use of renewable energy, suffers from poor catalyst stability, low yields, insufficient selectivity, and limited mass transfer in the reaction system, making efficient and sustainable large-scale production of hydrogen peroxide difficult to achieve.

[0058] The present invention provides a method for generating hydrogen peroxide based on Marangoni burst-driven micro-droplet interface, which has the following characteristics:

[0059] (1) Simple equipment: The process of generating hydrogen peroxide in the present invention has significant advantages over the industrial anthraquinone method and the photocatalytic method. The industrial anthraquinone method has the problem of complex equipment and the need for catalysts, and the photocatalytic method requires additional light sources, catalysts, or special environments. Both methods also require additional energy input. However, the present invention does not require catalysts, light sources, or special environments. The hydrogen peroxide generation process can proceed spontaneously at room temperature and pressure, regardless of whether there is light or not.

[0060] (2) Higher concentration: Compared with the current photocatalytic method for generating hydrogen peroxide, its effect is better than that of most photocatalysts.

[0061] (3) Alcohol can be recycled, and the theoretical recovery rate is as follows:

[0062] The saturated vapor pressure of a substance at different temperatures can be calculated according to the Antoine equation.

[0063] lgP=AB / (T+C) Formula (1)

[0064] Where: P is the saturated vapor pressure of the substance (mmHg); T is the temperature (°C); A, B, and C are Antoine constants.

[0065] The theoretical condensation recovery is calculated according to the following formula.

[0066] η=(P1-P2) / P1 Formula (2)

[0067] Where: P1 is the saturated vapor pressure at the temperature before condensation, and P2 is the saturated vapor pressure at the temperature after condensation.

[0068] According to formula (2), when the oil phase is heated to 50°C and the condensation temperature is 4°C, the theoretical recovery rate of isopropanol can reach 94.4% (in actual application, it may fluctuate due to different operating conditions).

[0069] Figure 1 This is a schematic diagram of a device for generating hydrogen peroxide at a micro-droplet interface based on Marangoni bursting, according to an embodiment of the present invention. The device includes a peristaltic pump system, a temperature control system, and a condensation system.

[0070] The peristaltic pump system includes a first peristaltic pump and a second peristaltic pump; the temperature control and condensation system includes a heating device and a condensation device.

[0071] In the present invention, the Marangoni burst-driven generation of hydrogen peroxide at the micro-droplet interface must satisfy the following requirements: diffusion coefficient S>0.

[0072] Where, the diffusion coefficient S = γ oa -γ ma -γ mo ; γ oa is the interfacial tension between the water-immiscible organic reagent and air, γ ma is the interfacial tension between the aqueous solution containing volatile organic solvents and air, γ mo It is the interfacial tension between an aqueous solution containing a volatile organic solvent and a water-immiscible organic reagent.

[0073] When S>0, the mixture will spread on the oil surface and explode.

[0074] Example 1

[0075] A method for generating hydrogen peroxide at a micro-droplet interface based on Marangoni burst driving, comprising the following steps:

[0076] Step 1. Connect the device:

[0077] 500 mL of sunflower oil was added to a 1000 mL round-bottom flask, and an isopropyl alcohol-water solution (isopropyl alcohol volume concentration 60%) was added to a conical flask;

[0078] The liquid inlet tube of the first peristaltic pump was immersed in the isopropanol-water solution, and the liquid outlet tube was sealed and connected to the feeding port on the top of the round-bottom flask through a silicone tube;

[0079] Place the round-bottom flask in a heating device (constant temperature water bath); connect the round-bottom flask to a condensing device (snake condenser), set the condensing water temperature to 4°C, and connect the condensing device outlet to a conical flask (receiving flask) filled with an isopropanol-water solution.

[0080] Step 2: Start the device

[0081] A constant temperature water bath was set to 50°C and maintained. Once the sunflower oil temperature stabilized at 50°C, the first peristaltic pump was activated, dripping an isopropyl alcohol-water solution onto the surface of the sunflower oil at a steady flow rate of 60 μL / min (one drop was 6 μL). Upon instillation of the isopropyl alcohol-water solution, Marangoni convection induced by the surface tension gradient drove the droplet to burst, forming droplets with a high specific surface area.

[0082] Figure 3 A top view of the droplet bursting process; Figure 4 Optical microscopy of the bursting process.

[0083] During the reaction, the volatile isopropyl alcohol vapor is condensed into liquid by a condenser and then flows back into a conical flask containing an isopropyl alcohol-water solution. As the isopropyl alcohol-water solution begins to condense and return to a receiving flask, a second condensation pump is activated to add water to the receiving flask, maintaining the isopropyl alcohol concentration in the isopropyl alcohol-water solution at 60% by volume. The system temperature and flow rate are maintained constant throughout the reaction.

[0084] Step 3: Product collection

[0085] After the reaction is completed, the first peristaltic pump and the second peristaltic pump stage heating device are turned off to obtain hydrogen peroxide in the aqueous phase.

[0086] In Example 1 of the present invention, γ oa ≈32mN / m; when the IPA content is 60%, γ ma ≈23mN / m; γ mo ≈3mN / m, diffusion coefficient S=6mN / m>0, the solution can spread on the oil phase and produce Marangoni phenomenon.

[0087] In Example 1 of the present invention, an isopropyl alcohol aqueous solution with a volume concentration of 60% was used, and the rate of hydrogen peroxide generation was 34.5 ppm / s.

[0088] On the basis of Example 1, the volume concentration of isopropanol in the isopropanol-water solution was adjusted, and the concentration of hydrogen peroxide was detected by using potassium titanium oxalate to obtain the concentration of hydrogen peroxide generated by isopropanol-water solutions of different concentrations (measured after 16 minutes of dropwise addition). Figure 2 shown.

[0089] Specifically, when a 40% volume concentration isopropyl alcohol aqueous solution is used, the rate of hydrogen peroxide generation is 5 ppm / s; when a 50% volume concentration isopropyl alcohol aqueous solution is used, the rate of hydrogen peroxide generation is 13.5 ppm / s; when a 70% volume concentration isopropyl alcohol aqueous solution is used, the rate of hydrogen peroxide generation is 61.4 ppm / s; and when a 80% volume concentration isopropyl alcohol aqueous solution is used, the rate of hydrogen peroxide generation is 100.7 ppm / s.

[0090] Example 2

[0091] The only difference from Example 1 is that the isopropyl alcohol-water solution is replaced by an ethanol-water solution with a volume concentration of 80%.

[0092] Among them, γ oa ≈32mN / m, γ ma ≈29mN / m, γ mo ≈2.5mN / m, diffusion coefficient S=0.5mN / m.

[0093] In Example 2, the generation rate of hydrogen peroxide was 53 ppm / s.

[0094] Example 3

[0095] The only difference from Example 1 is that the isopropyl alcohol-water solution is replaced by an acetone-water solution with a volume concentration of 90%.

[0096] Among them, γ oa ≈32mN / m, γ ma ≈25mN / m, γ mo ≈3mN / m, diffusion coefficient S=4mN / m.

[0097] In Example 3, the generation rate of hydrogen peroxide was 41.8 ppm / s.

[0098] Figure 5 The concentration of hydrogen peroxide generated in Examples 2 and 3 of the present invention (measured after 8 minutes of dripping)

[0099] Example 4

[0100] It adopts 10-layer stacked modular device, and each module occupies an area of ​​1m 2 , integrated 10m 2Oil phase reaction area (sunflower oil), oil phase thickness is controlled to 1cm, total volume is 100L. Each module has 6000 parallel reaction channels (10m 2 ×600 channels / m 2 ), the channel material is made of polytetrafluoroethylene resistant to organic solvents to ensure interface stability.

[0101] Equipped with a high-precision peristaltic pump array (total flow rate 21.6L / h), the single-channel droplet acceleration rate is constant at 60μL / min, with each droplet volume being 6μL. The next droplet is added after the previous droplet's inner diameter shrinks. A jacketed electric heating device maintains the oil phase temperature at 50±2°C, and an accompanying temperature sensor provides real-time feedback to the central control system.

[0102] A total of 100L of sunflower oil was injected into the 10-layer module, and the heating system was started to 50°C; 1000L of an aqueous solution containing 60% isopropyl alcohol (volume concentration) was prepared and evenly distributed to each reaction channel through a peristaltic pump group at a total flow rate of 21.6L / h. The micro-droplet generation process at the oil-water interface was detected to ensure a stable burst frequency (the burst time of each droplet was ≤5s); potassium titanium oxalate titration was used to control the concentration fluctuation range to less than 2ppm. A serpentine condensation device was integrated on the top of the module, and the condensed water temperature was controlled at 4°C. Isopropyl alcohol vapor was introduced into the condensation system through a negative pressure pipe, with a theoretical recovery efficiency of 94.4%. The recovered liquid was circulated to the feed tank after concentration detection.

[0103] After 30 minutes, the test results showed that the H2O2 concentration in the water phase was 38 ppm.

[0104] Comparative Example 1

[0105] 5 mg of TiO2 was dissolved in 5 mL of n-propanol solution (350 mM) and irradiated for 2 h using a light source with a wavelength of 365 nm in an oxygen blowing environment to produce 423.2 μM H2O2.

[0106] Comparative Example 2

[0107] 20 mg of g-C3N4 photocatalyst was added to 5 mL of 90% ethanol solution, blown with O2 for 5 min, and irradiated with a light source with a wavelength of 450 nm for 24 h to produce 30 μM H2O2.

[0108] Comparative Example 3

[0109] Take 3 mL containing 1 μM [Ru II A dilute sulfuric acid (2 M) solution of (Me2phen)3]SO4 photocatalyst was irradiated with a light source of 450 nm wavelength in an oxygen-blown environment for 9 h to produce 612 μM H2O2.

[0110] Comparative Example 4

[0111] 50 mg of resorcinol-formaldehyde resin catalyst was added to 30 mL of pure water, oxygen O2 was blown in, and a light source with a wavelength of 523 nm was used for irradiation for 24 h to generate 99 μM H2O2.

[0112] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for generating hydrogen peroxide based on Marangoni burst-driven micro-droplet interface, characterized in that: The following steps are involved: The water-immiscible organic reagent is heated to 30-60° C., and an aqueous solution containing a volatile organic solvent is added dropwise to the water-immiscible organic reagent to induce droplet bursting to form microdroplets through the Marangoni effect at the oil-water interface, followed by oil-water separation to obtain hydrogen peroxide in the aqueous phase; Moreover, the diffusion coefficient S>0 is required; S=γ oa -γ ma -γ mo ; Among them, γ oa is the interfacial tension between the water-immiscible organic reagent and air, γ ma is the interfacial tension between the aqueous solution containing volatile organic solvents and air, γ mo It is the interfacial tension between an aqueous solution containing a volatile organic solvent and a water-immiscible organic reagent.

2. The method for producing hydrogen peroxide according to claim 1, wherein The water-immiscible organic agent includes vegetable oil; the vegetable oil includes sunflower oil, castor oil or peanut oil.

3. The method for producing hydrogen peroxide according to claim 1, wherein The volatile organic solvents are ketones and alcohols.

4. The method for producing hydrogen peroxide according to claim 3, wherein The ketones include acetone; the alcohols include isopropyl alcohol or ethanol.

5. The method for producing hydrogen peroxide according to claim 1, wherein After the inner diameter of the previous drop of the aqueous solution containing the volatile organic solvent shrinks, the next drop of the aqueous solution containing the volatile organic solvent is dropped.

6. The method for producing hydrogen peroxide according to claim 1, wherein The dripping speed is 40-80 μL / min.

7. The method for producing hydrogen peroxide according to claim 1, wherein The volatile organic solvent is isopropyl alcohol.

8. The method for producing hydrogen peroxide according to claim 1, wherein The method further comprises the step of recovering the volatile organic solvent through a condensation device.

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