Application of quinone compound as photocatalyst in photocatalytic production of hydrogen peroxide

Abstract

The invention discloses an application of a quinone compound as a photocatalyst in photocatalytic production of hydrogen peroxide. The quinone micromolecules are used as a photocatalyst for oxygen reduction reaction under illumination to generate hydrogen peroxide. The used system is a two-phase system composed of water and an organic solvent, the photocatalyst exists in an organic phase, generated hydrogen peroxide is extracted into a water phase in situ, and meanwhile, the organic solvent in the organic phase is oxidized to generate a high-added-value product. The photocatalytic reaction system has the excellent characteristics of simplicity in preparation, low cost, mild reaction conditions, high stability, high reaction rate and the like, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the field of photocatalytic preparation of hydrogen peroxide, and in particular to the application of quinone compounds as photocatalysts in photocatalytic production of hydrogen peroxide. Background Art

[0002] As a strong oxidant, hydrogen peroxide (H2O2) has been widely used in industrial and domestic fields, including wastewater treatment, chemical synthesis, industrial bleaching, energy storage, medical disinfection, etc., and has become a promising energy carrier in fuel cells. In the context of green and sustainable development, the demand for hydrogen peroxide is increasing rapidly. It is estimated that by 2027, the global market share of H2O2 will reach about 5.7 million tons, and its influence in the field of sustainable energy will become increasingly greater. The traditional production method of H2O2 is mainly based on the 2-ethylanthraquinone method, but its preparation process involves the introduction of hydrogen and the catalysis of precious metal catalysts. This makes it difficult to ensure the safety of traditional processes, and they are not green and sustainable, and do not meet the development needs of today's society.

[0003] The photocatalytic H2O2 production technology itself has the advantages of being green, clean, low-consumption, safe, and stable. Specifically, it uses solar energy to convert H2O or O2 into H2O2. In the process of photocatalytic H2O2 production, sunlight is used as an energy source and green reactants are used as substrates under mild conditions of natural environment and pressure. It meets the needs of sustainable development in the current society and is expected to become an ideal method to replace traditional processes.

[0004] However, the main reason that limits the industrial development of photocatalytic H2O2 production technology is the slow H2O2 production rate and poor stability of the photocatalyst, which are far from meeting the requirements of industrial production. The photocatalytic H2O2 production rate of most materials remains at μmol g -1 h -1 Even in the presence of sacrificial agents, the photocatalytic H2O2 production rate can only reach 0-10 mmol g -1 h -1 At present, the material with the highest SCC value for photocatalytic H2O2 production is the phenolic resin prepared by Liu et al., which has an SCC value of 1.2% and a H2O2 production rate of 1820 μmol g -1 h -1 This is far from meeting the needs of industrial production. In addition, such materials usually have poor light stability and are not suitable for long-term high-efficiency production of H2O2. Therefore, in order to achieve low-consumption, clean, safe and sustainable H2O2 production, it is necessary to develop a new type of efficient and stable photocatalytic system. Summary of the invention

[0005] The purpose of the present invention is to provide a solution for using quinone compounds as photocatalysts to produce hydrogen peroxide in a photocatalytic manner.

[0006] In order to achieve the purpose of the present invention, in a first aspect, the present invention provides the use of quinone compounds as photocatalysts in photocatalytic production of hydrogen peroxide.

[0007] The quinone compound can be selected from benzoquinone small molecules, naphthoquinone small molecules, acenaphthenequinone small molecules, anthraquinone small molecules, phenanthrenequinone small molecules, diketone small molecule compounds and the like.

[0008] Further, the quinone compound can be selected from p-benzoquinone and its derivatives, o-benzoquinone and its derivatives, benzocyclobutanedione and its derivatives, 1,4-naphthoquinone and its derivatives, 1,2-naphthoquinone and its derivatives, 1,5-naphthoquinone and its derivatives, 2,6-naphthoquinone and its derivatives, 1,4-acenaphthenequinone and its derivatives, 1,4-anthraquinone and its derivatives, 5,12-tetraacenoquinone and its derivatives, 9,10-phenanthrenequinone and its derivatives, etc., and their structures are as follows: Wherein, R is any substituent at any position, and R can be selected from methyl, ethyl, methoxy, amino, hydroxyl, carboxyl, cyano, halogen element substituent, benzene ring substituent, etc.

[0009] In the second aspect, the present invention provides a method for photocatalytically generating hydrogen peroxide from oxygen molecules, wherein oxygen or air is introduced into a two-phase system consisting of water (deionized water) and an organic solvent in the presence of a catalyst quinone compound, and hydrogen peroxide (the hydrogen peroxide is derived from the reduction of oxygen) is generated under light conditions, and the generated hydrogen peroxide is extracted in situ into the water phase, while the organic solvent in the organic phase is oxidized to generate high value-added products, such as benzaldehyde, n-valeraldehyde, benzoquinone, 2,5-diformylfuran, etc.

[0010] In the present invention, hydrogen peroxide comes from the reduction of oxygen, and oxygen or air needs to be introduced into the reactor during the reaction process.

[0011] Furthermore, the organic solvent and water are mixed in any volume ratio. The organic solvent is immiscible with water, and the organic solvent includes aromatic compounds and aliphatic compounds.

[0012] Preferably, the organic solvent includes but is not limited to the following categories: high molecular weight fatty alcohols (butanol, pentanol, hexanol, etc.), halogen element substituted alkanes (dichloromethane, dichloroethane, etc.), n-hexane, cyclohexane, aromatic alkanes (toluene, xylene, ethylbenzene, heavy aromatics, etc.) and aromatic alcohols (phenol, hydroquinone, benzyl alcohol, phenylethyl alcohol, etc.).

[0013] Furthermore, the method comprises the following steps: S1, dissolving the quinone compound in the organic solvent, and performing ultrasound to ensure that the quinone compound is completely dissolved; S2, adding a certain volume (such as an equal volume) of water to the organic solvent containing the quinone compound to form a two-phase system of water-organic solvent containing the catalyst; S3, transferring the configured two-phase system to a light reaction container made of a light-transmitting material (such as quartz) to ensure that the catalytic system can fully absorb light; S4, introducing oxygen or air into the above two-phase system for 10-30 min, so that the dissolved oxygen in the two-phase system reaches a saturated state; S5, adding light to the photoreactor to drive the photocatalytic reaction, during the light irradiation process, continuously introducing oxygen or air, and controlling the temperature at 0-100°C; S6. After a period of reaction, when the hydrogen peroxide in the aqueous phase reaches a desired concentration, the aqueous phase is separated from the organic phase to obtain a pure hydrogen peroxide solution; S7. Adding water again into the organic phase can continue to produce hydrogen peroxide.

[0014] Furthermore, in steps S4 and S5, the flow rate of oxygen or air is 100-1000 mL / min, and the reaction pressure is 1 atm.

[0015] Furthermore, in step S5, the illumination is one or more of xenon lamp illumination, sunlight irradiation, and LED illumination, and the wavelength of the light is 200-800 nm and the intensity is 10-1000 mW / cm 2 .

[0016] In the present invention, the catalyst can be recycled.

[0017] The present invention relates to the application of a quinone small molecule photocatalytic system in the photocatalytic production of hydrogen peroxide. The quinone small molecule is used as a photocatalyst to produce hydrogen peroxide by oxygen reduction reaction under light. The nitrogen atom in the quinone structure small molecule acts as an active center for oxygen reduction to produce hydrogen peroxide by oxygen reduction. The quinone small molecule is dissolved in an organic solvent and forms a two-phase system consisting of water-organic solvent with water. While light-induced oxygen reduction produces hydrogen peroxide, the organic solvent can be oxidized to produce a product with higher added value. The generated hydrogen peroxide is extracted in situ into the water phase, which increases the rate of photocatalytic production of hydrogen peroxide and ensures the stability of the catalyst.

[0018] By means of the above technical solution, the present invention has at least the following advantages and beneficial effects: (i) The photocatalytic reaction system of the present invention is simple to prepare, low in cost, and has mild reaction conditions.

[0019] (ii) The photocatalytic reaction system of the present invention has high stability and a fast reaction rate for photocatalytic production of hydrogen peroxide.

[0020] (III) The photocatalytic reaction system of the present invention can simultaneously prepare oxidation products with higher added value, thereby generating higher economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a picture of the photocatalytic preparation of hydrogen peroxide in the o-xylene-water two-phase system constructed using phenanthrenequinone molecules as catalysts in Example 1 of the present invention.

[0022] Figure 2 This is a curve showing the change in H2O2 concentration over time in the photocatalytic production of the o-xylene-water two-phase system constructed using phenanthrenequinone molecules as catalysts in Example 1 of the present invention.

[0023] Figure 3 This is a curve chart showing the change in H2O2 concentration over time of the photocatalytic production of the cyclopenta-tetraphenyl-1,2-dione molecular catalyst in water-o-xylene and water-n-pentanol dual-phase bulk phases in Example 2 of the present invention.

[0024] Figure 4 This is a curve showing the change in H2O2 concentration over time in Example 4 of the present invention using 4-acenaphthenequinone or 1,4-anthraquinone catalyst in a water-benzyl alcohol dual phase.

[0025] Figure 5 This is a gas chromatogram of the organic phase after the reaction in Example 4 of the present invention. DETAILED DESCRIPTION

[0026] The present invention provides a novel photocatalytic system using quinone small molecules as a photocatalyst for efficient photocatalytic production of hydrogen peroxide.

[0027] The present invention provides a novel molecular photocatalytic system for photocatalytic H2O2 production. The small molecule is a small molecule with a quinone structure, including but not limited to benzoquinone small molecules, naphthoquinone small molecules, acenaphthenequinone small molecules, anthraquinone small molecules, phenanthrenequinone small molecules, diketone small molecules, etc.

[0028] The catalytic system is a two-phase system composed of water and an organic solvent. The organic solvent and water are immiscible, and the organic solvent can be an aromatic compound or an aliphatic compound, including but not limited to the following organic solvents: high molecular weight aliphatic alcohols (butanol, pentanol, hexanol, etc.), alkanes substituted with halogen elements (dichloromethane, dichloroethane, etc.), aromatic alkanes (toluene, xylene, ethylbenzene, heavy aromatics, etc.) and aromatic alcohols (phenol, hydroquinone, benzyl alcohol, phenylethyl alcohol, etc.).

[0029] In the present invention, the generation of hydrogen peroxide is driven under illumination conditions, wherein the illumination is one or more of xenon lamp illumination, sunlight irradiation, and LED illumination, and the wavelength of the light is in the range of 200 to 800 nm. The intensity of the illumination is 10 to 1000 mW / cm 2 .

[0030] In the two-phase system described in the present invention, quinone small molecules are dissolved and dispersed in the organic phase. Under light conditions, they can reduce the oxygen dissolved in the organic solvent to H2O2. The subsequently produced hydrogen peroxide is quickly extracted into the aqueous phase. This process can not only increase the production rate of H2O2 but also protect the small molecule catalyst and increase the photostability of the catalytic system.

[0031] In the two-phase system described in the present invention, while the quinone molecular catalyst reduces oxygen to generate H2O2, it may also oxidize the organic solvent to generate higher value-added products. This not only improves the rate of photocatalytic production of H2O2, but also reduces the cost of H2O2, thereby improving the value of the photocatalytic system.

[0032] When the photocatalytically produced H2O2 reaches the desired concentration, the H2O2 can be quickly separated. The reaction conditions are mild, the process is green and safe, and the organic phase system can be recycled and reused in intermittent batch reactions.

[0033] Among them, the process and steps of photocatalytic production of H2O2 by phenanthrenequinone small molecule photocatalytic system are as follows: S1. Dissolve a certain amount of phenanthrenequinone molecules in an organic solvent that is immiscible with water, and use ultrasound to ensure that the phenanthrenequinone molecules are completely dissolved.

[0034] S2. Add a certain volume (such as equal volume) of aqueous solution to the above-mentioned phenanthrenequinone molecule organic solvent to form a water-organic solvent two-phase system.

[0035] S3. Transfer the prepared two-phase system catalytic liquid to a quartz photoreaction container to ensure that the catalytic system can fully absorb light.

[0036] S4. Passing oxygen or air into the above two-phase system for 10-30 min to make the dissolved oxygen in the two-phase system reach a saturated state.

[0037] S5. Adding illumination to the photoreactor to drive the reaction, wherein the illumination is one or more of sunlight, xenon lamp illumination, and LED illumination, with a wavelength range of 300-800 nm and an intensity of 100-3000 mW / cm 2 During the illumination process, oxygen or air is continuously introduced and the temperature is controlled at 0~100℃.

[0038] S6. After a period of photocatalytic reaction, when the H2O2 in the water phase reaches the required concentration, the water phase and the organic phase are separated to obtain a pure H2O2 solution.

[0039] S7. After adding new pure water to the above organic phase, H2O2 can continue to be produced.

[0040] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art, and the raw materials used are all commercially available products.

[0041] Example 1 Weigh 0.30 g of phenanthrenequinone and place it in 30 mL of o-xylene or n-pentanol solution, and sonicate until phenanthrenequinone is completely dissolved.

[0042] 20 mL of deionized water was added to the o-xylene or n-pentanol solution of the above-mentioned phenanthrenequinone molecules to form a two-phase system of water-o-xylene or water-n-pentanol.

[0043] The above two-phase reaction solution was transferred to a quartz glass photoreactor and passed 80-100 mL min -1 Oxygen was continuously introduced at a flow rate of 30 min.

[0044] The light intensity is 100 mW cm -2 A 100 W xenon lamp equipped with a 420 nm filter was used as the light source to continuously illuminate the reaction system in the photoreactor. Oxygen was continuously introduced during the illumination process, and the reaction temperature was controlled at 25°C.

[0045] The H2O2 concentration of the aqueous solution in the biphasic system was tested at different reaction time points.

[0046] When the H2O2 concentration in the water phase reaches the required level, turn off the oxygen and light source, let the organic solvent and hydrogen peroxide solution stand for separation, take out the H2O2 solution, and then add new deionized water to produce the next batch of H2O2.

[0047] In this embodiment, the high value-added product generated in the organic phase is phthalic anhydride or n-valeraldehyde.

[0048] See the photocatalytic preparation of hydrogen peroxide in the o-xylene-water biphasic system using phenanthrenequinone molecules as catalysts. Figure 1 .

[0049] The change curve of H2O2 concentration over time in the o-xylene-water two-phase system photocatalyzed by phenanthrenequinone molecules is shown in Figure 2. Figure 2 .

[0050] Example 2 This embodiment provides a method for producing H2O2 using a photocatalytic system constructed with cyclopenta-tetraphenyl-1,2-dione as a photocatalyst, and the overall process is as follows: 1.0 g of cyclopentanetetraphenyl-1,2-dione was placed in 100 mL of o-xylene and ultrasonicated until cyclopentanetetraphenyl-1,2-dione was completely dissolved.

[0051] 100 mL of deionized water was added to the o-xylene solution of cyclopenta-tetracene-1,2-dione to form a water-o-xylene two-phase system; Transfer the above two-phase reaction solution to a 2 L beaker and pass 800-1000 mL min -1 Air was continuously passed through the chamber at a flow rate of 1.5 % for 30 min.

[0052] The system is continuously illuminated by adding outdoor sunlight as the light source, and air is continuously ventilated during the illumination process.

[0053] The H2O2 concentration of the aqueous solution in the biphasic system was tested at different reaction time points.

[0054] When the H2O2 concentration in the water phase reaches the required level, turn off the air, let the organic solvent and hydrogen peroxide solution stand for separation, take out the H2O2 solution, and then add new deionized water to produce the next batch of H2O2.

[0055] In this embodiment, the high value-added product generated in the organic phase is phthalic anhydride.

[0056] The time-dependent curve of H2O2 concentration produced by photocatalysis of cyclopenta-tetraphenyl-1,2-dione molecular catalyst in water-o-xylene and water-n-pentanol dual phases is shown in Figure 2. Figure 3 .

[0057] Example 3 This embodiment provides a method for producing H2O2 using a photocatalytic system constructed with 6-methyl-1,4-naphthoquinone as a photocatalyst, and the overall process is as follows: Weigh 0.50 g of 6-methyl-1,4-naphthoquinone into 20 mL of toluene solution and sonicate until 6-methyl-1,4-naphthoquinone is completely dissolved.

[0058] 20 mL of deionized water was added to the above 6-methyl-1,4-naphthoquinone toluene solution to form a water-toluene two-phase system; The above two-phase reaction solution was transferred to a quartz glass photoreactor and passed 80-100 mL min -1 Oxygen was continuously introduced at a flow rate of 30 min.

[0059] The reaction system in the photoreactor is continuously illuminated using an LED with a power of 24 W and a wavelength of 390 nm as the light source. Oxygen is continuously introduced during the illumination process, and the reaction temperature is controlled at 25°C.

[0060] The H2O2 concentration of the aqueous solution in the biphasic system was tested at different reaction time points.

[0061] When the H2O2 concentration in the water phase reaches the required level, turn off the oxygen and light source, let the organic solvent and hydrogen peroxide solution stand for separation, take out the H2O2 solution, and then add new deionized water to produce the next batch of H2O2.

[0062] In this embodiment, the high value-added products generated in the organic phase are benzyl alcohol and benzaldehyde.

[0063] Example 4 This embodiment provides a method for producing H2O2 using a photocatalytic system constructed with 1,4-acenaphthenequinone or 1,4-anthraquinone as a photocatalyst, and the overall process is as follows: Weigh 0.25 g of 1,4-acenaphthenequinone or 1,4-anthraquinone and place it in 20 mL of benzyl alcohol solution. Ultrasonicate until 1,4-acenaphthenequinone or 1,4-anthraquinone is completely dissolved.

[0064] Add 20 mL of deionized water to the above benzyl alcohol solution of 1,4-acenaphthenequinone or 1,4-anthraquinone to form a water-benzyl alcohol biphasic system; The above two-phase reaction solution was transferred to a quartz glass photoreactor and passed 80-100 mL min -1 Oxygen was continuously introduced at a flow rate of 30 min.

[0065] The reaction system in the photoreactor is continuously illuminated using an LED with a power of 24 W and a wavelength of 365 nm as the light source. Oxygen is continuously introduced during the illumination process, and the reaction temperature is controlled at 25°C.

[0066] The H2O2 concentration of the aqueous solution in the biphasic system was tested at different reaction time points.

[0067] When the H2O2 concentration in the water phase reaches the required level, turn off the oxygen and light source, let the organic solvent and hydrogen peroxide solution stand for separation, take out the H2O2 solution, and then add new deionized water to produce the next batch of H2O2.

[0068] In this embodiment, the high value-added products generated in the organic phase are benzaldehyde and benzoic acid.

[0069] The time-dependent curve of H2O2 concentration produced by photocatalysis of 1,4-acenaphthenequinone or 1,4-anthraquinone catalyst in water-benzyl alcohol dual phase is shown in Figure 2. Figure 4 .

[0070] After the photocatalytic H2O2 production process, the gas chromatogram of the organic phase is shown in Figure 5 .

[0071] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, these modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. Application of quinone compounds as photocatalysts in photocatalytic production of hydrogen peroxide; The quinone compound is selected from benzoquinone small molecules, naphthoquinone small molecules, acenaphthenequinone small molecules, anthraquinone small molecules, phenanthrenequinone small molecules, and diketone small molecules.

2. The use according to claim 1, characterized in that: The quinone compound is selected from p-benzoquinone and its derivatives, o-benzoquinone and its derivatives, benzocyclobutanedione and its derivatives, 1,4-naphthoquinone and its derivatives, 1,2-naphthoquinone and its derivatives, 1,5-naphthoquinone and its derivatives, 2,6-naphthoquinone and its derivatives, 1,4-acenaphthenequinone and its derivatives, 1,4-anthraquinone and its derivatives, 5,12-tetraacenoquinone and its derivatives, 9,10-phenanthrenequinone and its derivatives, and their structures are as follows: Wherein, R is any substituent at any position, and R is selected from methyl, ethyl, methoxy, amino, hydroxyl, carboxyl, cyano, halogen element substituent, and benzene ring substituent.

3. A method for photocatalytically generating hydrogen peroxide from oxygen molecules, characterized in that: In the presence of a catalyst quinone compound, oxygen or air is introduced into a two-phase system consisting of water and an organic solvent, hydrogen peroxide is generated under light conditions, the generated hydrogen peroxide is extracted in situ into the water phase, and at the same time, the organic solvent in the organic phase is oxidized to generate a high value-added product; The quinone compound is the same as that described in claim 1 or 2.

4. The method according to claim 3, characterized in that: The organic solvent and water are mixed in any volume ratio.

5. The method according to claim 3, characterized in that: The organic solvent is immiscible with water, and the organic solvent includes aromatic compounds and aliphatic compounds; Preferably, the organic solvent is selected from one or more of butanol, pentanol, hexanol, dichloromethane, dichloroethane, n-hexane, cyclohexane, toluene, xylene, ethylbenzene, heavy aromatics, benzyl alcohol, and phenylethyl alcohol.

6. The method according to claim 3, characterized in that The following steps are involved: S1, dissolving the quinone compound in the organic solvent, and performing ultrasound to ensure that the quinone compound is completely dissolved; S2, adding a certain volume of water to the organic solvent containing the quinone compound to form an organic solvent-water two-phase system containing the catalyst; S3, transferring the configured two-phase system to a light reaction container made of a light-transmitting material to ensure that the catalytic system can fully absorb light; S4, introducing oxygen or air into the above two-phase system for 10-30 min, so that the dissolved oxygen in the two-phase system reaches a saturated state; S5, adding light to the photoreactor to drive the photocatalytic reaction, during the light irradiation process, continuously introducing oxygen or air, and controlling the temperature at 0-100°C; S6. After a period of reaction, when the hydrogen peroxide in the aqueous phase reaches a desired concentration, the aqueous phase is separated from the organic phase to obtain a pure hydrogen peroxide solution; S7. Adding water again into the organic phase can continue to produce hydrogen peroxide.

7. The method according to claim 6, characterized in that In steps S4 and S5, the flow rate of oxygen or air is 100-1000 mL / min, and the reaction pressure is 1 atm.

8. The method according to claim 6, characterized in that In step S5, the illumination is one or more of xenon lamp illumination, sunlight irradiation, and LED illumination, the wavelength of the light is 200-800 nm, and the intensity of the illumination is 10-1000 mW / cm 2 .

9. The method according to any one of claims 3 to 8, characterized in that: The catalyst can be recycled.

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