Method for preparing hydrogen peroxide by microwave-induced graphene plasma

Abstract

The invention provides a method for preparing hydrogen peroxide by microwave-induced graphene plasma, which comprises the following steps: preparing a graphene water-based dispersion liquid, transferring into a reaction container, introducing micro-nano bubbles, and applying microwave irradiation to the graphene water-based dispersion liquid to obtain a hydrogen peroxide solution. Graphene is dispersed in a high-density micro-nano bubble solution, the graphene is excited through microwave irradiation to generate liquid-phase plasma, and a bubble-plasma interface coupling structure is formed; the plasma and the micro-nano bubbles are coupled to generate a transient high-temperature and high-pressure (the pressure intensity is greater than 22.1 MPa, and the temperature is greater than 3000K) confined environment, a similar supercritical water reaction micro-area is constructed, and water splitting is accelerated into hydrogen free radicals H, hydroxyl free radicals OH and hydrogen peroxide H2O2 by virtue of interface charge enrichment and high specific surface area mass transfer characteristics of the bubbles. No catalyst is needed, and green and efficient preparation of hydrogen peroxide can be realized only by consuming electric energy.

Description

Technical Field

[0001] The present invention relates to the technical field of plasma physics research, and more particularly to a method for preparing hydrogen peroxide by using microwave-induced plasma. Background Art

[0002] Hydrogen peroxide (H2O2) is a widely used green oxidant. Currently, its industrial production is mainly based on the anthraquinone method, which relies on precious metal palladium catalysts, is costly and has a lengthy process. It also faces problems such as high pollutant treatment costs. Supercritical water (SCWO, temperature > 374.2°C, pressure > 22.1MPa) has become an ideal medium for the preparation of H2O2 due to its unique physical and chemical properties. Supercritical water has a low dielectric constant and high ion product, and is miscible with organic matter, increasing the concentration of free radicals by 10 3 The supercritical water method can generate H2O2 at a rate of more than 5 times the energy of conventional methods, and it also has its own catalytic effect, eliminating the need for additional catalysts. Theoretically, the H2O2 yield can be 5-8 times that of traditional methods. However, supercritical water technology has the following limitations: it requires a Hastelloy reactor that can withstand extreme conditions, which is costly and prone to material failure; it consumes a lot of energy, and the high temperature environment accelerates the decomposition of H2O2, creating a vicious cycle of "high energy consumption and low yield"; and it can easily cause side reactions in which H2O2 reverts to water due to the slow diffusion of free radicals. These technical bottlenecks limit the efficient production of H2O2 from supercritical water. Therefore, innovative technological breakthroughs that promote localization, low energy consumption, and rapid mass transfer are urgently needed to achieve efficient and green production of H2O2.

[0003] In recent years, microwave-induced graphene plasma technology and micro-nano bubble technology have attracted much attention as two emerging methods for controlling interfacial reactions. Microwave-induced graphene excites localized surface plasmon resonance at the nanoscale through dielectric loss to produce high-temperature hotspots (>3000K). The energy is focused on the reaction interface, resulting in a lower energy barrier for water splitting (<240kJ / mol). Micro-nano bubble technology exhibits unique advantages in pressure field control. The rupture of micro-nano bubbles generates transient high pressure (>22.1MPa), which can inhibit the decomposition of H2O2 according to Le Chatelier's principle. The high-pressure environment can also accelerate free radical mass transfer collisions and increase the rate of OH coupling to generate H2O2. However, the temperature of the bubble system is insufficient (<500K), and the water splitting efficiency is low. It needs to work in conjunction with a high-temperature energy source to break through the bottleneck of reaction kinetics. Summary of the Invention

[0004] In response to the above-mentioned technical problems existing in the prior art, the present invention provides a method for preparing hydrogen peroxide using microwave-induced graphene plasma. This method utilizes the energy coupling mechanism of graphene plasma cracking and micro-nano bubble cavitation. It does not require a catalyst and consumes only electrical energy to efficiently prepare hydrogen peroxide, achieving a hydrogen peroxide yield of 5.4 mol / g / h, thereby achieving efficient, green, and low-cost preparation of hydrogen peroxide.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for preparing hydrogen peroxide by microwave-induced graphene plasma comprises the following steps:

[0007] S1, mixing graphene and water to uniformly disperse graphene particles in the water to obtain a graphene dispersion;

[0008] S2. Transferring the graphene dispersion into a reaction container and introducing micro-nano bubbles into the graphene dispersion, and then irradiating the graphene dispersion with microwaves to obtain a hydrogen peroxide solution.

[0009] In some embodiments, the graphene concentration in the graphene dispersion is 0.01-2 mg / L.

[0010] In some embodiments, the carrier gas for introducing micro-nano bubbles into the graphene dispersion is at least one of air, oxygen, nitrogen, hydrogen, and an inert gas.

[0011] In some embodiments, the power density of microwave irradiation is 1-40 mW / cm 3 .

[0012] In some embodiments, the average diameter of the micro-nano bubbles is 10-500 nm.

[0013] In some embodiments, the pressure in the reaction vessel is controlled to be 0.1-3 MPa.

[0014] In some embodiments, the temperature of the graphene dispersion is 50-80°C.

[0015] In some embodiments, when microwave irradiation is performed, the temperature of the supercritical water-like microenvironment formed in the graphene dispersion is greater than 3000 K and the pressure is greater than 22.1 MPa.

[0016] The present invention also provides a system for implementing the method of any of the above-mentioned embodiments, the system comprising a reaction vessel, a micro-nano bubble generating device, a refrigeration system and a microwave generating device, the refrigeration system and the micro-nano bubble generating device being connected to the reaction vessel through pipelines respectively; the microwave resonant cavity of the microwave generating device is arranged outside the reaction vessel.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The method of the present invention, its reaction principle is as follows Figure 1As shown, high-density micro-nano bubbles are introduced into a graphene dispersion, and liquid-phase plasma is generated on the graphene surface through microwave irradiation. An interface coupling structure is formed between the surface of the micro-nano bubbles and the surface of the plasma. The cavitation collapse of the micro-nano bubbles and the coupling of the liquid-phase plasma produce a transient high-temperature and high-pressure confined environment (pressure > 22.1 MPa, temperature > 3000 K), constructing a supercritical water-like reaction microzone at the graphene-bubble interface. The interfacial charge enrichment and the high specific surface area mass transfer characteristics of the bubbles work synergistically to accelerate the splitting of water into hydrogen radicals·H, hydroxyl radicals·OH and H2O2, promoting the formation of H2O2.

[0019] The present invention utilizes the interface and energy coupling mechanism of graphene plasma cracking and micro-nano bubble cavitation, without the need for a catalyst and consuming only electrical energy, to achieve efficient production of H2O2 (H2O2 yield reaches 5.4 mol / g / h), thus realizing efficient, green and low-cost production of hydrogen peroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the reaction principle of the present invention;

[0021] Figure 2 is a process flow chart of the present invention;

[0022] Figure 3 Schematic diagram of the structure of the reaction system of the present invention;

[0023] Among them, 1-water cooler, 2-micro-nano bubble generator, 3-microwave generating device, 4-reaction container, 5-pipeline, 6-microwave resonant cavity. DETAILED DESCRIPTION

[0024] The following description sets forth numerous specific details to facilitate a thorough understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific implementations disclosed below.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0026] The raw materials or reagents used in the following examples are specifically from:

[0027] Graphene: 2-3 layers of graphene are prepared by chemical vapor deposition;

[0028] Micro-nano bubbles: generated by micro-nano bubble generator;

[0029] The reaction apparatus used is as Figure 3 As shown: the water cooler 1 is connected to the water bath interlayer of the reaction vessel 4 through the pipe 5 (blue pipe) and circulates, and is used to cool the graphene dispersion in the reaction vessel 4; the micro-nano bubble generator 2 is connected to the graphene dispersion in the inner layer of the reaction vessel 4 through the pipe 5 (gray pipe) and circulates, continuously injecting micro-nano bubbles into the graphene dispersion; the reaction vessel 4 is placed inside the microwave generating device 3, and the microwave resonant cavity 6 of the microwave generating device 3 is placed outside the reaction vessel 4.

[0030] The reaction device is started to synthesize H2O2: a water source is injected into the water bath interlayer of the reaction vessel 4 through the water cooler 1, graphene and deionized water are added to the inner layer of the reaction vessel 4, and stirred evenly to obtain a graphene dispersion; then the micro-nano bubble generator 2 is turned on and micro-nano bubbles are injected into the graphene dispersion, and finally the microwave resonant cavity 6 in the microwave generator 3 is turned on to generate microwaves, which irradiate the graphene dispersion to produce H2O2.

[0031] Devices for detecting H2O2: UV-visible spectrophotometer, pipette, cuvette and other conventional laboratory equipment.

[0032] Example 1 Effect of different microwave powers on H2O2 yield

[0033] like Figure 1 As shown, the method for preparing H2O2 by microwave-induced graphene plasma of this embodiment includes the following steps:

[0034] S1, preparing a graphene mixed solution: adding graphene to a reaction vessel, injecting water into the water bath interlayer of the reaction vessel 4 through a water chiller 1, adding graphene and deionized water to the inner layer of the reaction vessel 4, and stirring to obtain a graphene mixed solution with a concentration of 0.5 mg / mL;

[0035] S2, open the micro-nano bubble generator 2, inject micro-nano bubbles with an average diameter of 200 nm and a carrier gas of air into the graphene mixture, control the pressure in the reaction vessel to 0.5 MPa, and form a gas-liquid-solid mixed liquid system;

[0036] S3, opening the microwave resonant cavity 6 in the microwave generator 3, generating microwaves to irradiate the graphene mixed liquid, the microwave irradiation excites the graphene surface to generate liquid-phase plasma, forming a micro-nano bubble-plasma coupling interface, the micro-nano bubble cavitation collapse and the liquid-phase plasma coupling to produce a transient high-temperature and high-pressure confined environment (pressure>22.1MPa, temperature>3000K), constructing a supercritical water-like environment at the plasma-bubble interface, the interfacial charge enrichment and the high specific surface area mass transfer characteristics of the bubble synergistically accelerate the splitting of water into hydrogen radicals H, hydroxyl radicals OH and hydrogen peroxide H2O2, and obtain an H2O2 solution;

[0037] Among them, the frequency of the microwave generating device is 2.45GHz, the irradiation time is 10min, the power of the microwave generating device is controlled to 500W, 1000W, and 1500W respectively, the temperature of the graphene mixed liquid can be controlled at 60±5℃, and the volume of the graphene mixed liquid is 1L.

[0038] The experimental results are shown in Table 1 below.

[0039] Table 1 Effect of different microwave powers on H2O2 yield

[0040]

[0041] Example 2 Effect of different graphene dispersion concentrations on H2O2 yield

[0042] like Figure 1 As shown, the method for preparing hydrogen peroxide by microwave-induced graphene in this embodiment includes the following steps:

[0043] S1, preparing a graphene mixed solution: adding graphene to a reaction vessel, injecting water into the water bath interlayer of the reaction vessel 4 through a water chiller 1, adding graphene and deionized water to the inner layer of the reaction vessel 4, and stirring to obtain graphene mixed solutions of different concentrations;

[0044] S2, open the micro-nano bubble generator 2, inject micro-nano bubbles with an average diameter of 200 nm and a carrier gas of air into the graphene mixture, control the pressure in the reaction vessel to 0.5 MPa, and form a gas-liquid-solid mixed liquid system;

[0045] S3, opening the microwave resonant cavity 6 in the microwave generator 3, generating microwaves to irradiate the graphene mixed liquid, the microwave irradiation excites the graphene surface to generate liquid-phase plasma, forming a micro-nano bubble-plasma coupling interface, the micro-nano bubble cavitation collapse and the liquid-phase plasma coupling to produce a transient high-temperature and high-pressure confined environment (pressure>22.1MPa, temperature>3000K), constructing a supercritical water-like environment at the plasma-bubble interface, the interfacial charge enrichment and the high specific surface area mass transfer characteristics of the bubble synergistically accelerate the splitting of water into hydrogen radicals H, hydroxyl radicals OH and hydrogen peroxide H2O2, and obtain an H2O2 solution;

[0046] The frequency of the microwave generator is 2.45 GHz, the microwave power is 1000 W, the irradiation time is 10 min, the temperature of the graphene dispersion can be controlled at 60±5° C., and the volume of the graphene mixed liquid is 1 L.

[0047] The experimental results are shown in Table 2 below.

[0048] Table 2 Effect of different graphene dispersion concentrations on H2O2 yield

[0049]

[0050] Example 3 Effect of different micro-nano bubble atmospheres on H2O2 yield

[0051] like Figure 1 As shown, the method for preparing hydrogen peroxide by microwave-induced graphene in this embodiment includes the following steps:

[0052] S1, preparing a graphene mixed solution: adding graphene to a reaction vessel, injecting water into the water bath interlayer of the reaction vessel 4 through a water chiller 1, adding graphene and deionized water to the inner layer of the reaction vessel 4, and stirring to obtain graphene mixed solutions of different concentrations;

[0053] S2, open the micro-nano bubble generator 2, inject micro-nano bubbles of different carrier gases into the graphene mixture, control the pressure in the reaction container to 0.5 MPa, and form a gas-liquid-solid mixed liquid system;

[0054] S3, opening the microwave resonant cavity 6 in the microwave generator 3, generating microwaves to irradiate the graphene mixed liquid, the microwave irradiation excites the graphene surface to generate liquid-phase plasma, forming a micro-nano bubble-plasma coupling interface, the micro-nano bubble cavitation collapse and the liquid-phase plasma coupling to produce a transient high-temperature and high-pressure confined environment (pressure>22.1MPa, temperature>3000K), constructing a supercritical water-like environment at the plasma-bubble interface, the interfacial charge enrichment and the high specific surface area mass transfer characteristics of the bubble synergistically accelerate the splitting of water into hydrogen radicals H, hydroxyl radicals OH and hydrogen peroxide H2O2, and obtain an H2O2 solution;

[0055] Among them, the frequency of the microwave generating device is 2.45GHz, the power is 1000W, the irradiation time is 10min, the temperature of the graphene dispersion can be controlled at 60±5°C, and the volume of the graphene mixed liquid is 1L.

[0056] The experimental results are shown in Table 3 below.

[0057] Table 3 Effects of different micro-nano bubble atmospheres on H2O2 yield

[0058]

[0059] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing hydrogen peroxide by microwave-induced graphene plasma, characterized in that: The following steps are involved: S1, mixing graphene and water to uniformly disperse graphene particles in the water to obtain a graphene dispersion; S2. Transferring the graphene dispersion into a reaction container and introducing micro-nano bubbles into the graphene dispersion, and then irradiating the graphene dispersion with microwaves to obtain a hydrogen peroxide solution.

2. The method for preparing hydrogen peroxide by microwave-induced graphene according to claim 1, wherein In the graphene dispersion, the graphene concentration is 0.01-2 mg / L.

3. The method for preparing hydrogen peroxide by microwave-induced graphene plasma according to claim 1, wherein: The carrier gas for introducing micro-nano bubbles into the graphene dispersion is at least one of air, oxygen, nitrogen, hydrogen and an inert gas.

4. The method for preparing hydrogen peroxide by microwave-induced graphene plasma according to claim 1, wherein: The power density of microwave irradiation is 1-40mW / cm 3 .

5. The method for preparing hydrogen peroxide by microwave-induced graphene plasma according to claim 1, wherein: The average diameter of the micro-nano bubbles is 10-500 nm.

6. The method for preparing hydrogen peroxide by microwave-induced graphene plasma according to claim 1, wherein: The pressure in the reaction vessel was controlled to be 0.1-3 MPa.

7. The method for preparing hydrogen peroxide by microwave-induced graphene plasma according to claim 1, wherein: The temperature of the graphene dispersion is 50-80°C.

8. The method for preparing hydrogen peroxide by microwave-induced graphene plasma according to claim 1, wherein: When microwave irradiation is performed, the temperature of the supercritical water-like microenvironment formed in the graphene dispersion is greater than 3000K and the pressure is greater than 22.1MPa.

9. A system for implementing the method according to any one of claims 1 to 8, characterized in that: The invention comprises a reaction container, a micro-nano bubble generating device, a refrigeration system and a microwave generating device. The refrigeration system and the micro-nano bubble generating device are respectively connected to the reaction container through pipelines; the microwave resonant cavity of the microwave generating device is arranged outside the reaction container.

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