Electrochemical synthesis method of hydrogen peroxide

Abstract

The invention discloses an electrochemical synthesis method of hydrogen peroxide. Under the mild conditions of normal temperature and normal pressure, palladium-based electrodes are used as a cathode and an anode, the cathode electrolyzes water to produce active hydrogen, and meanwhile, the anode oxidizes formaldehyde to produce active hydrogen; meanwhile, the strategy that sulfo-anthraquinone is reduced by active hydrogen to synthesize H2O2 is adopted. A palladium membrane electrode loaded with Pd crystals is designed to ensure that active hydrogen rapidly diffuses to a palladium layer and shuttles back and forth into an ionic liquid organic phase containing sulfo-anthraquinone, sulfo-anthraquinone is directly reduced into sulfo-anthrahydroquinone, and then oxygen is catalyzed to obtain an ionic liquid organic phase containing hydrogen peroxide. And extracting the organic phase by using electrolyte-free water to obtain hydrogen peroxide. Under the current density of 30 milliamperes / cm < 2 >, the cumulative concentration of 6-8% is realized for H2O2, and meanwhile, a high-value formate product is obtained. By adjusting the extraction phase ratio, the Faraday efficiency of hydrogen peroxide production can reach 90%.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical technology, and relates to an electrochemical synthesis method of hydrogen peroxide under mild conditions of normal temperature and pressure, and specifically to an electrochemical synthesis method of hydrogen peroxide and potassium formate. In particular, it relates to an electrochemical method combined with a traditional anthraquinone process to prepare hydrogen peroxide and simultaneously produce a high-value formate byproduct. Background Art

[0002] Hydrogen peroxide (H2O2) is one of the most important chemicals used in chemical synthesis, water treatment, papermaking, and energy storage. It has been widely used in industrial processes, including fiber and paper production, water treatment, and environmental remediation in acidic and neutral media. Currently, the production of commercial H2O2 mainly relies on large-scale anthraquinone hydrogenation processes; however, this technology requires huge infrastructure capital investment and is energy-intensive. It requires high temperature and high pressure conditions during operation and also emits a large amount of hazardous waste. In order to minimize the transportation cost from the manufacturing point to the end user, the traditional anthraquinone process concentrates H2O2 to a certain concentration, which creates a potential explosion risk and brings safety issues. In addition, the addition of stabilizers to prevent H2O2 from degradation usually has a negative impact on the chemical activity of H2O2, and its chemical residues also cause concerns in water treatment applications. Therefore, people are eager to achieve sustainable production of H2O2 at room temperature and pressure, so as to provide a portable and safe H2O2 supply for dispersed or remote areas.

[0003] Electrochemical synthesis provides a cleaner and more economical alternative to the anthraquinone reduction process. However, this method still faces the following challenges: -2 How to achieve high Faraday efficiency under different high current densities, how to increase the concentration of synthesized H2O2, and how to prevent impurities such as specific salts or acids and alkalis in the cathode electrolyte solution from being brought into the product, causing the purity of H2O2 to decrease. Summary of the invention

[0004] The purpose of the present invention is to maintain the advantages of the traditional anthraquinone method, change the anthraquinone hydrogenation reduction process with certain safety hazards into electrochemical reduction, and then introduce oxygen to produce hydrogen peroxide, so as to design a green and efficient electrochemical synthesis method of hydrogen peroxide, and also a green and efficient synchronous electrochemical synthesis method of hydrogen peroxide and potassium formate.

[0005] The present invention produces active hydrogen by electrolyzing water at the cathode and produces active hydrogen by oxidizing formaldehyde at the anode, thereby reducing anthrahydroquinone to oxygen and two electrons to produce hydrogen peroxide. The oxidation product of formaldehyde is formate, and the economic value of formate is much higher than that of hydrogen peroxide.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] <First aspect>

[0008] The present invention provides a method for producing H2O2 by electrochemical method, wherein the method is prepared by electrolytic coupling anthraquinone, and comprises the following steps:

[0009] S1, electrochemical reaction produces active hydrogen;

[0010] S2, the cathode electrolytic cell of the electrochemical reaction cell is connected to an external organic cathode reduction cell, and the palladium-based cathode in the electrochemical reaction is arranged between the cathode electrolytic cell and the organic cathode reduction cell, so that the cathode electrolytic cell is separated from the organic cathode reduction cell;

[0011] and / or the anode electrolytic cell of the electrochemical reaction cell is connected to an external organic anode reduction cell, and the palladium-based anode in the electrochemical reaction is arranged on a communication channel between the anode electrolytic cell and the organic anode reduction cell, so that the anode electrolytic cell is separated from the organic anode reduction cell;

[0012] S3, the active hydrogen produced in step S1 overflows into the ionic liquid electrolyte solution containing sulfoanthraquinone in the reduction tank through the palladium-based electrode, and anthraquinone hydrogenation reduction reaction occurs. The obtained organic solution reacts with oxygen to prepare hydrogen peroxide. The present invention adopts a strategy of electrolysis to produce active hydrogen under mild conditions of normal temperature and pressure, and at the same time, the active hydrogen reduces sulfoanthraquinone to synthesize H2O2. The electrochemical cathode and anode of the present invention are combined to produce hydrogen peroxide, and the concentration thereof is as high as 6-8%. At the same time, there is no acid, no alkali, and no electrolyte in the H2O2 solution.

[0013] The phase separation in the above step S2 means that the solutions in the two tanks are not interconnected and the solution molecules are independent of each other. In the system of the present invention, active hydrogen is provided by electrocatalysis, the external chamber (reduction tank) uses active hydrogen to carry out corresponding chemical reactions, and the electrode itself acts as a catalyst for the reaction. In particular, in the case of four chambers (i.e., double reduction tanks), electrocatalytic double hydrogenation of the same organic matrix anthraquinone AQ to generate anthrahydroquinone AHQ is achieved.

[0014] As an embodiment of the present invention, in step S1, active hydrogen is produced by electrolyzing water at the cathode, and active hydrogen is produced by oxidizing formaldehyde at the anode.

[0015] The volume ratio of the aqueous solution to the organic solution for extraction can be adjusted.

[0016] As one embodiment of the present invention, the anode electrolytic cell and the cathode electrolytic cell are separated by an AEM membrane.

[0017] As one embodiment of the present invention, a hydrogen peroxide solution is added to the solution obtained after anodization, and the solution is evaporated to obtain a formate.

[0018] As one embodiment of the present invention, the palladium-based electrode includes a Pd electrode and a PdNP / Pd electrode.

[0019] As an embodiment of the present invention, in step S3, after the obtained organic solution reacts with oxygen, the organic phase is collected after extraction with aqueous solution and transported to the reduction tank for repeated use. The organic phase is an ionic liquid organic phase containing sulfonyl anthraquinone. The organic solution obtained by the reaction of the obtained organic solution with oxygen is recorded as organic solution B. During extraction, the volume ratio of the aqueous solution for extraction to the organic solution B is 1:1-1:5.

[0020] As an embodiment of the present invention, the obtained organic solution is transported to an oxidation pond for oxygen aeration and then transported to an extraction pond for aqueous solution extraction. The oxygen introduced into the oxidation pond has a flow rate of 20-100 ml min -1 dm -1 The hydrogen peroxide solution obtained by extraction can be stored or used.

[0021] As an embodiment of the present invention, in step S3, the ionic liquid electrolyte in the ionic liquid electrolyte solution is selected from at least one of [BMIM][PF6], [BMIM][SbF6], and [BMIM][FSI]+. In some embodiments, the concentration of sulfonanthraquinone in the ionic liquid is selected to be 50-100 mM.

[0022] <Second Aspect>

[0023] The present invention provides a special electrochemical system for the above-mentioned electrochemical method for producing H2O2. The system is a 4-H type electrolytic cell, which sequentially comprises a connected organic cathode reduction cell, a cathode electrolytic cell, an anode electrolytic cell, and an organic anode reduction cell; the cathode electrolytic cell and the anode electrolytic cell are separated by an AEM membrane, a palladium-based cathode is provided on the communication channel between the organic cathode reduction cell and the cathode electrolytic cell to separate them, and a palladium-based anode is provided on the communication channel between the organic anode reduction cell and the anode electrolytic cell to separate them; the organic cathode reduction cell and the organic anode reduction cell are respectively loaded with an ionic liquid electrolyte solution containing sulfonyl anthraquinone.

[0024] In some embodiments, the cathode electrolytic cell contains an aqueous electrolyte solution; the anode electrolytic cell contains a formaldehyde solution. In the electrochemical system of the present invention, the electrolysis time is 1-10 hours, the voltage is 1.5-5.0V, and the current density is 10-100mA cm -2 , the concentration of hydrogen peroxide at the cathode can reach 5-10%, and the concentration of hydrogen peroxide at the anode can reach 2-4%.

[0025] As an embodiment of the present invention, the system further comprises an oxidation tank and an extraction tank connected in sequence; the oxidation tank is connected to an organic cathode reduction tank and an organic anode reduction tank respectively. The organic solution in the organic cathode reduction tank and the organic anode reduction tank enters the extraction tank for extraction and separation with water after oxygenation reaction in the oxidation tank; the organic phase obtained by extraction is an ionic liquid organic phase containing sulfonyl anthraquinone, which is re-input into the organic cathode reduction tank and / or the organic anode reduction tank through a pipeline for repeated use.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1) The present invention designs a dual-electrode hydrogenation strategy. When formaldehyde and water are used as proton sources in the anolyte and catholyte, respectively, the four-chamber assembly can realize the electrocatalytic double hydrogenation of the same organic matrix anthraquinone AQ to generate anthrahydroquinone AHQ in the chamber outside the electrochemical cell.

[0028] 2) The hydrogen peroxide prepared by electrolytically coupling anthraquinone of the present invention has high concentration, high purity, good quality, and does not contain acid, alkali and inorganic salt.

[0029] 3) The electrolytic coupling anthraquinone preparation of carbon emission has low energy consumption, anthraquinone can be reused, and no secondary pollutants are generated in the whole process, which is green and safe.

[0030] 4) The electrolytic coupled anthraquinone preparation of the present invention can combine the anode and cathode to simultaneously produce H2O2.

[0031] 5) The electrolytic coupling anthraquinone preparation of the present invention can additionally produce high value-added formate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0033] Figure 1 is the reaction equation for the electrochemical anthraquinone hydrogenation to produce hydrogen peroxide;

[0034] Figure 2 Schematic diagram of the electrocatalytic reaction mechanism.

[0035] Figure 3 Comparison of simulated dissolution performance of three ionic liquids;

[0036] Figure 4 The UV-Vis images of anthraquinone in three ionic liquids;

[0037] Figure 5 is the SEM image of Pd;

[0038] Figure 6 is the TEM image of the electrode;

[0039] Figure 7 This is a comparison chart of the ECSA performance of the electrodes;

[0040] Figure 8 is the XRD pattern of Pd electrode;

[0041] Fig. 9 The ESR diagrams are the anode organic tank, anode water tank, cathode organic tank, and cathode water tank;

[0042] Fig.10 is a graph of hydrogen peroxide production;

[0043] Fig.11 This is the electrode stability experiment diagram;

[0044] Fig.12 Schematic diagram of 4-H electrolysis system;

[0045] Fig.13 This is a physical picture of the 4-H electrolysis system;

[0046] Fig.14 Figure 1 is a diagram of the generated potassium formate product;

[0047] Fig.15 For the performance comparison of ionic liquids;

[0048] Fig.16 Comparison of the solubility properties of ionic liquids. DETAILED DESCRIPTION

[0049] The present invention is described in detail below in conjunction with embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, some adjustments and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0050] The present invention provides a method for producing H2O2 by electrochemical method, wherein the method is prepared by electrolytic coupling anthraquinone, and comprises the following steps:

[0051] S1, electrochemical reaction produces active hydrogen;

[0052] S2, the cathode electrolytic cell of the electrochemical reaction cell is connected to an external organic cathode reduction cell, and the palladium-based cathode in the electrochemical reaction is arranged between the cathode electrolytic cell and the organic cathode reduction cell, so that the cathode electrolytic cell is separated from the organic cathode reduction cell;

[0053] and / or the anode electrolytic cell of the electrochemical reaction cell is connected to an external organic anode reduction cell, and the palladium-based anode in the electrochemical reaction is arranged on a communication channel between the anode electrolytic cell and the organic anode reduction cell, so that the anode electrolytic cell is separated from the organic anode reduction cell;

[0054] S3, the active hydrogen produced in step S1 overflows into the ionic liquid electrolyte solution containing sulfoanthraquinone in the reduction tank through the palladium-based electrode, and anthraquinone hydrogenation reduction reaction occurs. The obtained organic solution reacts with oxygen to prepare hydrogen peroxide. The present invention adopts a strategy of electrolysis to produce active hydrogen under mild conditions of normal temperature and pressure, and at the same time, the active hydrogen reduces sulfoanthraquinone to synthesize H2O2. The electrochemical cathode and anode of the present invention are combined to produce hydrogen peroxide, and the concentration thereof is as high as 6-8%. At the same time, there is no acid, no alkali, and no electrolyte in the H2O2 solution.

[0055] Figure 1 is the reaction equation for electrochemical anthraquinone hydrogenation to produce hydrogen peroxide, Figure 1 It can be seen that the sulfonanthraquinone molecular formula selected in the present invention is as follows Figure 1 As shown, the subsequent sulfonyl anthraquinone is this substance. Sulfonyl anthraquinone and anthrahydroquinone can be converted into each other, and oxygen can directly oxidize anthrahydroquinone to generate hydrogen peroxide, which is the basis for electrocatalytic production of hydrogen peroxide.

[0056] Example 1: Donar number experiment of ionic liquids

[0057] For the probe substance, a certain amount of NaClO4 was dissolved in water to obtain a sodium perchlorate solution. Then, the solution was transferred to a 5 mm NMR precision sample coaxial tube. A 3 M NaCl aqueous solution was sealed in the coaxial tube as a reference. The donor number and the chemical shift of 23Na NMR were calculated according to the equation.

[0058] All electrochemical measurements were performed at ambient temperature (25 ± 1 °C) using a VMP-3 potentiostat (Biologic Science Instruments) with a three-electrode electrochemical cell. All reported potentials are referenced to RHEM KOH by calibration using Pt as the working electrode in H2 saturated 1.0. Unless otherwise stated, a platinum mesh was used as the counter electrode. A leak-free Ag / AgCl reference electrode was used for experiments performed in alkaline electrolytes and was stored in saturated KCl solution when not in use. The Ag / AgCl reference electrode was checked regularly relative to the original reference electrode to ensure that no potential drift occurred. The electrode potential was converted to the RHE scale using E(RHE) = E(Ag / AgCl) + 0.197 V + 0.059 × pH to facilitate unification to a standard reversible electrode.

[0059] Example 2: Quantitative and qualitative analysis of anthraquinone

[0060] The electrostatic potentials (ESP) of [BMIM][FSI], [BMIM][PF6], [BMIM][SbF6], H2O2 and 1,5-anthraquinone disulfonic acid, as well as the binding energy and charge transfer between the above ionic liquids and H2O2 or 1,5-anthraquinone disulfonic acid were calculated using the DMol3 module in Materials Studio (MS) 2020.

[0061] First, the generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional was used to fully relax each component. A dual numerical quality basis set with polarization function was used. The iteration tolerance for energy change, force, and displacement was 1×10 -5 Ha, and In the self-consistent field (SCF) procedure, 10 -6 au is used to converge the standard electron density. After structural optimization, H2O2 or 1,5-anthraquinone disulfonic acid is adsorbed onto the energy-favorable sites of the ionic liquid using the adsorption positioning tool in MS. Each pair is then freely optimized using the DMol3 module. Finally, a single-point energy calculation is performed, and the electron density, electrostatic potential, and Mulliken charge of each atom are output simultaneously. The binding energy of each ionic liquid and sulfonanthraquinone is calculated to determine in which solvent the solubility of sulfonanthraquinone is greatest.

[0062] Figure 3 are the simulated calculated values ​​of three ionic liquids. The present invention evaluates the compatibility between ionic liquids and sulfonyl anthraquinone through three dimensions. The three dimensions are E T (30), DN, and BE. By calculating the values, it was determined that the ionic liquid [BMIM][PF6] had the highest binding energy with sulfonanthraquinone and was insoluble in water, thus showing excellent performance in the subsequent extraction step. Fig.16 Comparison of the actual solubility properties of ionic liquids. Figure 4 is the solubility diagram of sulfonanthraquinone in the above three ionic liquids; Figure 4 It can be seen that the absorbance of sulfonanthraquinone in [BMIM][PF6] is the largest, which is consistent with the calculation results.

[0063] Example 3, "4-H" electrolytic cell structure

[0064] like Fig.12 , Fig.13As shown, the flow system for continuous electrochemical production of hydrogen peroxide includes four electrochemical cells, namely, an organic cathode reduction cell, a cathode electrolytic cell, an anode electrolytic cell, and an organic anode reduction cell; an oxidation cell and an extraction cell. A high-temperature silicone rubber sheet (50A duromer) is used to separate the middle of each two electrochemical cells. In order to meet the requirements of electrode materials, a cavity of a certain area is made on the silicon wafer (i.e., the high-temperature silicone rubber sheet), and palladium foil electrodes of a certain area are used as cathodes and anodes to cover the cavities on the silicon wafer; and the two half-reaction cells (cathode electrolytic cell and anode electrolytic cell) in the middle are separated by an anion exchange membrane (covering the cavity on the silicon wafer) to provide a certain activity area; the four electrochemical cells are well sealed. The active hydrogen generated by the aqueous cathode electrolyte flow and the active hydrogen generated by the oxidation of the anode formaldehyde electrolyte are overflowed into the ionic liquid electrolyte flow containing sulfoanthraquinone in the organic cathode reduction tank and the organic anode reduction tank through the palladium foil electrode, respectively. The reduced sulfoanthraquinone hydroquinone enters the oxidation tank from the organic cathode reduction tank and the organic anode reduction tank, respectively, and reacts with oxygen to regenerate sulfoanthraquinone and hydrogen peroxide. A peristaltic pump is used to pump these gas flows. The pressure regulating chamber is used to buffer the fluctuations of the flow rate and the gas inlet pressure. After mixing and precipitation, it is brought into the extraction tank for extraction and separation with water. The regenerated sulfoanthraquinone is put into the organic cathode reduction tank and the organic anode reduction tank again for repeated use.

[0065] Figure 2 Schematic diagram of electrocatalytic reaction mechanism. Figure 2 It can be seen that the reactions in the four channels (OCR, CE, AE, and QAR) are as follows. In OCR, only the hydrogenation of sulfoanthraquinone is completed. In CE, it is shown that water generates active hydrogen on the Pd electrode. In AE, the oxidation reaction of formaldehyde occurs. The intermediate products of the reactions are as follows. Figure 2 As shown, hydrogenation of the sulfonanthraquinone occurs in QAR.

[0066] Example 4: Synchronous electrochemical synthesis of hydrogen peroxide and potassium formate

[0067] The simultaneous synthesis experiment of hydrogen peroxide and potassium formate was carried out in the 4-H type electrochemical electrolyzer constructed above. Fig.12 , 13As shown, according to Example 3, from left to right are the organic cathode reduction tank, cathode electrolytic tank, anode electrolytic tank, and organic anode reduction tank. The organic cathode reduction tank contains 100mL [BMIM] [PF6] + 50, 65, 75, 100mM sulfonanthraquinone, the cathode electrolytic tank is 100mL sodium sulfate electrolyte aqueous solution, the anode electrolytic tank is 100mL 1.0M KOH + 0.6M HCHO, and the organic anode reduction tank is 100mL [BMIM] [PF6] + 50, 65, 75, 100mM sulfonanthraquinone. Voltages of 1.5, 2.5, 3.5, and 5.0V are applied to the entire electrolytic tank, and the reaction time is 1h-10h. The solutions in the organic cathode reduction tank and the organic anode reduction tank after the reaction are transferred to the oxygen cylinder, and the oxygen flow rate introduced is 25ml min -1 dm -1 、35ml min -1 dm -1 、55ml min -1 dm -1 、65ml min -1 dm -1 、100ml min -1 dm -1 After oxygen was introduced for 30 minutes, the solution (5 mL) in the organic cathode reduction tank and the organic anode reduction tank was transferred to the extraction bottle, and then pure water (5 mL) was added to the extraction bottle. The extraction bottle was shaken for about 10 minutes to allow the solution to fully contact and mix. After standing for 10-20 minutes, the hydrogen peroxide content in the aqueous solution in the extraction bottle was measured.

[0068] The solution in the anode electrolytic cell is taken out, evaporated and concentrated until the aqueous solution almost disappears completely, and then filtered to obtain potassium formate crystals, which are then placed in a drying oven and dried for more than 6 hours.

[0069] Fig.11 This is a stability test of the four slots (OCR, CE, AE, QAR) described in Example 4 in 1.0 M KOH, that is, the current method, that is, after applying a 3.5 V potential to the working electrode of the electrochemical system, the function relationship between the current response and time is measured. If the current fluctuation is not large, the stability of the electrode can be evaluated. It can be seen that the electrode remains stable after 360 hours of operation.

[0070] Example 5, Identification of H2

[0071] The purpose of detecting hydrogen is to test the performance of the electrode for hydrogen evolution, so as to determine its ability to generate active hydrogen. The H2 released by electrolysis was analyzed by gas chromatography (GC, SRI 8610C) equipped with a molecular sieve 13 filling column, a HayesSep D filling column and a thermal conductivity detector. Ar was used as the carrier gas.

[0072] Fig. 9 The NMR characterization diagrams of the four channels (OCR, CE, AE, QAR) described in Example 4 show that active hydrogen (H*) was detected in all four channels. Fig.10 The concentration of hydrogen peroxide generated after 5 hours of electrolysis in the four tanks (OCR, CE, AE, QAR) described in Example 4. It can be seen that after 5 hours, 6.522% of hydrogen peroxide was generated in CE.

[0073] Example 6. Preparation of Catalyst

[0074] The only difference between this embodiment and embodiment 4 is that the catalyst is PdNP / Pd membrane electrode.

[0075] Catalyst PdNP / Pd film electrode was prepared by electrodeposition method using 15.9 mM PdCl2 and 1.0 M HCl as electrolyte. Specifically, the Pd film as working electrode was sandwiched between the electrochemical chamber and the chemical chamber, and Pt mesh and Ag / AgCl (saturated KCl) electrode were used as counter electrode and reference electrode in the electrochemical chamber, respectively.

[0076] Figure 5 It is the SEM characterization picture of the electrode; Figure 6 is the TEM characterization image of the electrode; Figure 5 , Figure 6 It can be seen that Pd has been successfully loaded on the Pd foil electrode sheet. Figure 8 XRD characterization of the electrode further confirmed the deposition of Pd. The purpose of loading Pd is to increase the electrochemical active specific surface area. Figure 7 is a numerical comparison chart of electrochemical active specific surface area; Figure 7 It can be seen that compared with the electrode without Pd deposition, the electrochemically active specific surface area of ​​the electrode after deposition is nearly 40 times that of the former.

[0077] Example 7: Solubility experiment of sulfonyl anthraquinone in different ionic liquid solvents

[0078] The solubility of various ionic liquids and sulfoanthraquinone was compared. The same amount of sulfoanthraquinone was mixed with different ionic liquids and stirred for 10 hours, and the degree of solubility was evaluated by measuring UV-Vis. Fig.15 For all the listed types, except for [BMIM][PF6], [BMIM][SbF6], and [BMIM][FSI] ionic liquids, the spectrophotometric values ​​of sulfonanthraquinone detected in the remaining ionic liquids were all less than 0.3.

[0079] Example 8: Experiment on the output concentration of hydrogen peroxide at different sulfonyl anthraquinone concentrations

[0080] On the basis of Example 4, that is, in an electrochemical cell containing an organic cathode reduction tank, a cathode electrolytic tank, an anode electrolytic tank, and an organic anode reduction tank, the concentrations of sulfonanthraquinone in the organic cathode reduction tank and the organic anode reduction tank were adjusted, and the output concentrations of hydrogen peroxide were tested respectively. The concentrations of sulfonanthraquinone were 50, 65, 75, and 100 mM, and their concentrations were 6.522%, 8.13%, 8.744%, and 9.12%, respectively.

[0081] Example 9: Experiment on the output concentration of hydrogen peroxide at different electrolysis times

[0082] On the basis of Example 4, that is, in an electrochemical cell containing an organic cathode reduction tank, a cathode electrolytic cell, an anode electrolytic cell, and an organic anode reduction tank, the output concentration of hydrogen peroxide under voltages of 1.5, 2.5, 3.5, and 5.0 V were tested in the electrolytic cell, and the concentrations were 1.70%, 3.984%, 6.522%, and 8.113%, respectively.

[0083] Example 10: Experiment on the output concentration of hydrogen peroxide at different voltages

[0084] On the basis of Example 4, that is, in an electrochemical cell containing an organic cathode reduction tank, a cathode electrolytic tank, an anode electrolytic tank, and an organic anode reduction tank, the output concentration of hydrogen peroxide during electrolysis for 1 h to 10 h was tested, and the concentrations were 1.120%, 2.242%, 3.893%, 4.567%, 6.522%, 7.349%, 8.923%, 9.231%, 10.1%, and 10.777%, respectively.

[0085] Example 11: Experiment on the output concentration of hydrogen peroxide at different oxygen inlet flow rates

[0086] Based on Example 4, the output concentration of hydrogen peroxide was evaluated by adjusting the flow rate of oxygen. The flow rate of oxygen was adjusted to 25 ml min -1 dm -1 、35ml min -1 dm -1 、55ml min -1 dm -1 、65ml min -1 dm -1 、100mlmin -1 dm -1 The produced hydrogen peroxide concentrations were 3.331%, 6.522%, 7.11%, 7.89% and 6.974% respectively.

[0087] Example 12: Experiment on the output concentration of hydrogen peroxide at different extraction ratios

[0088] On the basis of Example 4, in the extraction cell, the output concentration of hydrogen peroxide was evaluated by adjusting the ratio of pure water to the ionic liquid organic phase. The volume ratios were adjusted to 1:1, 1:2.5, and 1:5, and the output concentrations of hydrogen peroxide were 1.576%, 3.664%, and 6.522%, respectively.

[0089] Example 13: Generation of formate product

[0090] In an electrochemical cell containing an organic cathode reduction tank, a cathode electrolytic tank, an anode electrolytic tank, and an organic anode reduction tank, the amount of formaldehyde in the solution is ensured to be sufficient during the electrolysis process. After electrolysis for 48 hours, 96 hours, 120 hours, and 150 hours, respectively, the pH of the anode is weakly alkaline. A very small amount of formic acid is added to the anode electrolytic tank to adjust the pH of the solution to neutral, and then a formate product is obtained by evaporation; Fig.14 .

[0091] In summary, the present invention is a strategy of using palladium-based electrodes as anodes and cathodes under mild conditions of normal temperature and pressure, electrolyzing water to produce active hydrogen at the cathode, and oxidizing formaldehyde at the anode to produce active hydrogen; at the same time, the active hydrogen reduces sulfonanthraquinone to synthesize H2O2. A palladium film electrode loaded with Pd crystals is designed to ensure that active hydrogen quickly diffuses into the palladium layer and shuttles into the ionic liquid organic phase containing sulfonanthraquinone, so that sulfonanthraquinone is directly reduced to sulfonanthrahydroquinone, and then catalyzes oxygen to obtain an ionic liquid organic phase containing hydrogen peroxide. The organic phase is then extracted with electrolyte-free water to obtain hydrogen peroxide. A cumulative concentration of 6-8% is achieved for H2O2 at a current density of 30 mA / cm2, and a high-value formate product is obtained. By adjusting the extraction ratio, the Faraday efficiency of hydrogen peroxide production can be as high as 90%.

[0092] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for producing H2O2 by electrochemical method, characterized in that: The method is to prepare anthraquinone by electrolytic coupling, comprising the following steps: S1, electrochemical reaction produces active hydrogen; S2, the cathode electrolytic cell of the electrochemical reaction cell is connected to an external organic cathode reduction cell, and the palladium-based cathode in the electrochemical reaction is arranged between the cathode electrolytic cell and the organic cathode reduction cell, so that the cathode electrolytic cell is separated from the organic cathode reduction cell; And / or, the anode electrolytic cell of the electrochemical reaction cell is connected to an external organic anode reduction cell, and the palladium-based anode in the electrochemical reaction is arranged on a communication channel between the anode electrolytic cell and the organic anode reduction cell, so that the anode electrolytic cell is separated from the organic anode reduction cell; S3, the active hydrogen generated in step S1 is shuttled through the palladium-based electrode to the ionic liquid electrolyte solution containing sulfonyl anthraquinone in the reduction tank, and anthraquinone hydrogenation reduction reaction occurs. The obtained organic solution reacts with oxygen to prepare hydrogen peroxide.

2. The electrochemical method for producing H2O2 according to claim 1, characterized in that: In step S1, active hydrogen is produced by electrolyzing water at the cathode, and active hydrogen is produced by oxidizing formaldehyde at the anode.

3. The electrochemical method for producing H2O2 according to claim 2, characterized in that: The anode electrolytic cell and the cathode electrolytic cell are separated by an AEM membrane.

4. The electrochemical method for producing H2O2 according to claim 2, characterized in that: A hydrogen peroxide solution is added to the solution obtained after anodization, and the formate is evaporated.

5. The electrochemical method for producing H2O2 according to claim 1, characterized in that: The palladium-based electrode includes one of a Pd electrode and a PdNP / Pd electrode.

6. The electrochemical method for producing H2O2 according to claim 1, characterized in that: In step S3, after the obtained organic solution reacts with oxygen, the organic phase is extracted with an aqueous solution and collected, and then transported to a reduction tank for repeated use.

7. The electrochemical method for producing H2O2 according to claim 6, characterized in that: The obtained organic solution is transported to an oxidation tank for oxygen aeration and then transported to an extraction tank for aqueous solution extraction.

8. The electrochemical method for producing H2O2 according to claim 1, characterized in that: In step S3, the ionic liquid electrolyte in the ionic liquid electrolyte solution is selected from at least one of [BMIM][PF6], [BMIM][SbF6], and [BMIM][FSI]+.

9. A dedicated electrochemical system for the electrochemical method for producing H2O2 according to any one of claims 1 to 8, characterized in that: The system is a 4-H type electrolytic cell, which comprises an organic cathode reduction cell, a cathode electrolytic cell, an anode electrolytic cell and an organic anode reduction cell in sequence; the cathode electrolytic cell and the anode electrolytic cell are separated by an AEM membrane, a palladium-based cathode is arranged on the communication channel between the organic cathode reduction cell and the cathode electrolytic cell to separate them, and a palladium-based anode is arranged on the communication channel between the organic anode reduction cell and the anode electrolytic cell to separate them; the organic cathode reduction cell and the organic anode reduction cell are respectively loaded with an ionic liquid electrolyte solution containing sulfonyl anthraquinone.

10. The dedicated electrochemical system according to claim 9, characterized in that: The system also includes an oxidation tank and an extraction tank which are connected in sequence; the oxidation tank is respectively connected to an organic cathode reduction tank and an organic anode reduction tank.

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