Method for preparing p-benzoquinone by electrocatalytic oxidation of phenol in water with carbon cloth loaded ferronickel catalyst

Abstract

The invention discloses a method for preparing p-benzoquinone through selective electrocatalytic oxidation of phenol by using a carbon cloth loaded ferronickel catalyst, the method adopts the carbon cloth loaded ferronickel catalyst as an anode to realize efficient conversion of phenol in an aqueous solution into p-benzoquinone, and the product is only p-benzoquinone. The method has the advantages of simple operation process, mild reaction conditions, high catalytic activity, high chemical selectivity and high target compound yield. The p-benzoquinone is prepared by oxidizing phenol in an alkaline environment, so that the use of toxic and harmful chemical oxidants is avoided, the pollutant emission is reduced from the source, and the method is an environment-friendly synthesis process and conforms to the development concept of green chemistry.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical advanced oxidation synthesis of p-benzoquinone, and particularly relates to a method for preparing p-benzoquinone by selective electrocatalytic oxidation of phenol by a carbon cloth-supported nickel-iron catalyst. Background Art

[0002] Phenolic compounds, as a typical class of organic pollutants, are widely present in various industrial wastewaters, such as coal washing wastewater and semi-coke wastewater. These pollutants have the significant characteristics of large emissions, high difficulty in degradation, and strong toxicity. In recent years, although researchers have developed a variety of processes such as photocatalysis, Fenton degradation, and electrocatalytic oxidation to degrade phenolic substances in wastewater, they still face many challenges in practical applications. Specifically, (1) the mineralization rate of phenolic wastewater is relatively low, making it difficult to achieve efficient treatment; (2) the energy consumption of the treatment process is high, resulting in a significant increase in wastewater treatment costs; (3) the direct use of mineralization to treat phenolic wastewater is not in line with the current concept of green development. Therefore, it is urgent to explore new treatment strategies to achieve the coordinated optimization of economic and environmental benefits in the wastewater treatment process.

[0003] Wastewater resource utilization has broad application prospects as a feasible way to treat industrial wastewater in a low-carbon and green way. p-Benzoquinone usually appears as a low-yield intermediate in the degradation process of phenols, and is often regarded as a by-product because it requires the use of precision instruments for detection. However, in fact, p-Benzoquinone is a key raw material for a variety of chemical products and is widely used in the fields of polymerization inhibitors, developers and cosmetics. In addition, p-Benzoquinone is also an excellent energy storage material and shows great application potential in the field of new generation energy. Given that its market price is much higher than that of phenolic compounds, the selective conversion of phenolic compounds into p-Benzoquinone can not only circumvent the high cost and high carbon emission problems brought about by traditional oxidation processes, but also achieve efficient recovery of high value-added resources.

[0004] The overall reaction for hydrogen production from water electrolysis involves the decomposition of water molecules when an electric current passes through electrodes, with hydrogen evolved at the cathode and oxygen evolved at the anode. The electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) play a decisive role in the performance of water electrolysis devices. Regardless of whether the electrolyte is acidic or alkaline, the OER involves a complex four-electron transfer process, while the HER only involves a two-electron transfer process. Consequently, the electron transfer kinetics of the OER are slower and require a higher overpotential. Under standard conditions, the theoretical overpotentials for the HER and OER are 0 V and 1.23 V, respectively. Therefore, designing efficient OER catalysts is key to improving the efficiency of electrochemical water splitting. Currently, the most widely used OER catalysts are Ir- and Ru-based precious metal compounds, but their high cost and low availability limit their further commercial application. Therefore, the development of high-performance, high-availability, and low-cost anode catalysts has become a research hotspot. However, the low added value of the oxygen product of the anode OER, the slow kinetics, and the high reaction energy barrier all limit the efficiency of hydrogen production at the cathode. To solve this problem, electrocatalytic advanced oxidation processes (EOPs) can be used to replace OER to participate in the reaction, which can not only realize the resource utilization of phenol-containing wastewater, but also reduce the overpotential of the anode reaction, thereby improving the hydrogen production efficiency of the cathode.

[0005] Patent CN116375149A discloses a method for selectively converting phenol in water to p-benzoquinone using electrocatalytic oxidation. The method first uses electrodeposition to prepare a ruthenium-carbon porous electrode. Subsequently, an aqueous solution containing phenol and sodium sulfate is used as the anolyte, an aqueous sodium sulfate solution is used as the catholyte, and the prepared ruthenium-carbon porous electrode is used as the anode. A three-electrode system is used for an electrocatalytic oxidation reaction, thereby achieving the selective conversion of phenol to p-benzoquinone. At a voltage of 0.9 V, this method can achieve a 96.4% phenol removal rate within 150 minutes, and the yield of p-benzoquinone can reach 78.9%. However, the catalyst used in this method is a precious metal catalyst, which increases the processing cost to a certain extent.

[0006] Ni9S8-Ni prepared by ZhenHai Wen et al. (10.1002 / anie.202407079) 15 O 16 When the nickel foam catalyst oxidizes phenol to p-benzoquinone in an H-type electrolytic cell, it achieves a Faradaic current efficiency of 92%, demonstrating a high conversion rate. However, the preparation process of this nickel foam-based catalyst is complex, requires demanding conditions, and is expensive, which to some extent limits its practical application. Summary of the Invention

[0007] The purpose of the present invention is to provide a low-cost, highly selective method for preparing p-benzoquinone by electrocatalytic oxidation of phenol in water. The method uses a carbon cloth-supported nickel-iron catalyst as the anode, selectively oxidizes phenol in water to synthesize p-benzoquinone, while accelerating the hydrogen production efficiency of the cathode, thereby achieving the removal of phenol pollutants in water and the recovery of organic carbon resources.

[0008] The technical solution adopted in the present invention consists of the following steps:

[0009] Step 1: Preparation of carbon cloth-supported nickel-iron catalyst

[0010] Nickel is deposited on the pretreated carbon cloth by electrodeposition, and then the carbon cloth with nickel deposited is immersed in an ethanol aqueous solution containing a nickel source and an iron source at room temperature for 24 to 72 hours to obtain a carbon cloth-supported nickel-iron catalyst.

[0011] Step 2: Electrocatalytic oxidation of phenol to prepare p-benzoquinone

[0012] An aqueous solution containing phenol and KOH is used as the anolyte, the KOH aqueous solution is used as the catholyte, and the carbon cloth-supported nickel-iron catalyst prepared in step 1 is used as the anode. A three-electrode system is used to electrocatalytically oxidize phenol to prepare p-benzoquinone at a constant potential.

[0013] In the above step 1, the carbon cloth is sequentially ultrasonically treated in a 1 mol / L HCl aqueous solution, acetone, and deionized water for 20 to 30 minutes each, and then dried to obtain a pretreated carbon cloth.

[0014] In step 1 above, 0.1-0.5 mol / L nickel nitrate aqueous solution is used as the deposition solution, an Ag / AgCl electrode and a platinum sheet electrode are used as the reference electrode and the counter electrode, respectively, and the pretreated carbon cloth is used as the working electrode. Cyclic voltammetry is used to deposit nickel on the pretreated carbon cloth.

[0015] Furthermore, in the above step 1, cyclic voltammetry is preferably used to scan for 18 to 25 cycles in the range of -1.2 to 0.2 V at a scan rate of 4 to 6 mV / s to deposit nickel on the pretreated carbon cloth.

[0016] In the above step 1, the iron source is ferrous sulfate or ferrous chloride, and the nickel source is nickel nitrate or nickel sulfate.

[0017] Furthermore, in the above step 1, the mass ratio of the nickel source to the iron source is preferably 1:9 to 9:1, and the concentration of the iron source in the ethanol aqueous solution containing the nickel source and the iron source is 0.1 to 0.5 mol / L.

[0018] In the above step 1, the volume ratio of ethanol to deionized water in the ethanol aqueous solution is 1:1 to 5:1.

[0019] In the above step 2, preferably, the phenol concentration in the anolyte is 0.4-1.5 g / L, the KOH concentration is 1 mol / L, and the KOH concentration in the catholyte is 1 mol / L.

[0020] Furthermore, in the above step 2, phenol is preferably electrocatalytically oxidized to prepare p-benzoquinone at a constant potential of 0.5 to 0.9 V.

[0021] The beneficial effects of the present invention are as follows

[0022] The present invention adopts a carbon cloth-supported nickel-iron catalyst as an anode, selectively oxidizes phenol in water to synthesize p-benzoquinone, accelerates the hydrogen production efficiency of the cathode, realizes the removal of phenol pollutants in water and the recovery of organic carbon resources. The present invention adopts an electrochemical oxidation method, which is simple, highly controllable, and has mild reaction conditions. The carbon cloth-supported nickel-iron catalyst is a transition metal, simple to prepare, and has a lower cost than a noble metal catalyst. It has both high catalytic activity and high chemical selectivity, high phenol selectivity, and a high p-benzoquinone yield, and is suitable for large-scale industrial production. The present invention oxidizes phenol in an alkaline environment to prepare p-benzoquinone, avoids the use of toxic and harmful chemical oxidants, reduces pollutant emissions from the source, is an environmentally friendly synthesis process, and conforms to the development concept of green chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the SEM spectrum of the carbon cloth-supported nickel-iron catalyst prepared in Example 1.

[0024] Figure 2 This is the EDS spectrum of the carbon cloth-supported nickel-iron catalyst prepared in Example 1.

[0025] Figure 3 This is the XPS spectrum of the carbon cloth-supported nickel-iron catalyst prepared in Example 1.

[0026] Figure 4 It is a graph of the carbon cloth-supported nickel-iron catalyst prepared in Example 1 at a voltage of 0.545 V. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and examples, but the protection scope of the present invention is not limited to these examples.

[0028] Example 1

[0029] Step 1: Preparation of carbon cloth-supported nickel-iron catalyst

[0030] A 1 cm × 2 cm carbon cloth was ultrasonically treated in 1 mol / L HCl solution, acetone, and deionized water for 30 min each, followed by drying to obtain a pretreated carbon cloth. Cyclic voltammetry was performed using a 0.2 mol / L nickel nitrate solution as the deposition solution, an Ag / AgCl electrode, and a platinum sheet as the reference and counter electrodes, respectively, with the pretreated carbon cloth as the working electrode. Nickel was deposited on the pretreated carbon cloth by scanning for 20 cycles at a scan rate of 5 mV / s between -1.2 and 0.2 V, yielding a nickel-deposited carbon cloth. 0.973 g (3.5 mmol) of FeSO₄·7H₂O and 4.07 g (14 mmol) of Ni(NO₃)₂·6H₂O were added to 10 mL of deionized water and thoroughly dissolved. The resulting solution was then slowly poured into 40 mL of anhydrous ethanol and stirred thoroughly to obtain a nickel-iron mixed solution. The nickel-deposited carbon cloth was immersed in the nickel-iron mixed solution at room temperature for 48 h to obtain a carbon cloth-supported nickel-iron catalyst.

[0031] Field emission scanning electron microscopy (SEM) was used to characterize the microstructure of the obtained catalyst. Figure 1 It can be seen that the surface of the carbon cloth is covered with a dense nanosheet structure. These nanosheets are randomly interconnected to form a three-dimensional porous structure, forming a dense catalyst layer on the surface. Figure 2 From the EDS spectrum, it can be seen that nickel, iron, sulfur and oxygen elements are evenly distributed in the compact flaky material on the surface of the carbon cloth.

[0032] The obtained catalyst was subjected to X-ray photoelectron spectroscopy (XPS) test. Figure 3 It can be seen that the elements on the catalyst surface correspond to the EDS detection values, including nickel, iron, oxygen and sulfur. Figure 3 (a) In the 2p spectrum of nickel, the main peak of nickel binding energy is at 855.9 eV, which is much larger than the main peak of metallic nickel at 852.6 eV (2p 3 / 2 ) and nickel oxide main peak 853.7eV (2p 3 / 2 ), and the main peak of nickel hydroxide 855.6eV (2p 3 / 2 ) are similar, and the binding energy is 861.2eV (2p 3 / 2 ), which indicates that the nickel phase in the catalyst exists in the form of nickel hydroxide. Figure 3 (b) In the 2p spectrum of iron, it can be seen that the main peak of iron is concentrated at 712.19 eV, which also moves to the high-energy region compared with the main peaks of iron oxide at 710.8 eV and ferrous oxide at 710.6 eV. Combined with the satellite peaks, it can be judged that there are divalent and trivalent iron compounds. Figure 3 The main peak of oxygen in (c) is 531.5eV, and the satellite peak is 535.0eV. This may be because there is hydroxyl oxygen in the catalyst, which causes the satellite peak of the catalyst to move to the high energy region. Figure 3(d) The main peak binding energy of sulfur is 186.12 eV, which indicates that the sulfur element in the catalyst is in the form of sulfate ions (SO4 2- ) exists. The above analysis further confirms the conclusion drawn by EDS.

[0033] Step 2: Electrocatalytic Oxidation of Phenol to Prepare p-Benzoquinone: 0.471 g of phenol and 56.105 g (1 mol) of KOH were added to deionized water and diluted to a 1 L volumetric flask with deionized water. After mixing, 50 mL of the solution was taken and nitrogen was passed through for 30 minutes to remove oxygen from the solution to prevent phenol from being oxidized by dissolved oxygen and interfering with the test. After deoxygenation, the solution was electrolyzed as the anolyte in an H-type electrolytic cell using a 1 mol / L KOH solution as the catholyte, a Hg / HgO electrode as the reference electrode, a platinum electrode as the counter electrode, and the carbon cloth-supported nickel-iron catalyst prepared in Step 1 as the anode. Electrolysis was performed at 0.545 V for 12 hours. The resulting mixed solution was measured by UV-visible spectrophotometry to yield 92.6% p-benzoquinone.

[0034] from Figure 4 It can be seen that when phenol was oxidized at a voltage of 0.545 V, the catalyst activity remained stable after 12 hours of oxidation, and the current density did not change significantly.

[0035] Example 2

[0036] Step 1: Preparation of carbon cloth-supported nickel-iron catalyst

[0037] This step is the same as step 1 in Example 1.

[0038] Step 2: Electrocatalytic oxidation of phenol to prepare p-benzoquinone

[0039] In this step, electrolysis was performed at 0.515 V for 12 h. The other steps were the same as step 2 of Example 1. The yield of p-benzoquinone in the obtained mixed solution was measured by ultraviolet-visible spectrophotometry to be 89.9%.

[0040] Example 3

[0041] Step 1: Preparation of carbon cloth-supported nickel-iron catalyst

[0042] This step is the same as step 1 in Example 1.

[0043] Step 2: Electrocatalytic oxidation of phenol to prepare p-benzoquinone

[0044] In this step, electrolysis was performed at 0.575 V for 12 h. The other steps were the same as step 2 of Example 1. The yield of p-benzoquinone in the obtained mixed solution was measured by ultraviolet-visible spectrophotometry, and was 92.4%.

[0045] Example 4

[0046] Step 1: Preparation of carbon cloth-supported nickel-iron catalyst

[0047] This step is the same as step 1 in Example 1.

[0048] Step 2: Electrocatalytic Oxidation of Phenol to Prepare p-Benzoquinone: In this step, 0.941 g of phenol and 56.105 g (1 mol) of KOH were added to deionized water and diluted to a 1 L volumetric flask with deionized water. After mixing, 50 mL of the solution was taken and nitrogen was introduced for 30 minutes to remove oxygen from the solution to prevent phenol from being oxidized by dissolved oxygen and interfering with the test. The solution was electrolyzed as the anolyte of an H-type electrolytic cell, using a 1 mol / L KOH solution as the catholyte, a Hg / HgO electrode as the reference electrode, a platinum electrode as the counter electrode, and the carbon cloth-supported nickel-iron catalyst prepared in step 1 as the anode. Electrolysis was performed at 0.545 V for 24 hours. The resulting mixed solution was measured by UV-visible spectrophotometry to yield 93.1% p-benzoquinone.

Claims

1. A method for preparing p-benzoquinone by selective electrocatalytic oxidation of phenol using a carbon cloth-supported nickel-iron catalyst, characterized in that The method consists of the following steps: Step 1: Preparation of carbon cloth-supported nickel-iron catalyst nickel is deposited on the pretreated carbon cloth by electrodeposition, and then the carbon cloth with nickel deposited thereon is immersed in an ethanol aqueous solution containing a nickel source and an iron source at room temperature for 24 to 72 hours to obtain a carbon cloth-supported nickel-iron catalyst; Step 2: Electrocatalytic oxidation of phenol to prepare p-benzoquinone An aqueous solution containing phenol and KOH is used as the anolyte, the KOH aqueous solution is used as the catholyte, and the carbon cloth-supported nickel-iron catalyst prepared in step 1 is used as the anode. A three-electrode system is used to electrocatalytically oxidize phenol to prepare p-benzoquinone at a constant potential.

2. The method for preparing p-benzoquinone by selective electrocatalytic oxidation of phenol using a carbon cloth-supported nickel-iron catalyst according to claim 1, characterized in that: In step 1, the carbon cloth is ultrasonically treated in 1 mol / L HCl aqueous solution, acetone, and deionized water for 20 to 30 minutes each, and then dried to obtain a pretreated carbon cloth.

3. The method for preparing p-benzoquinone by selective electrocatalytic oxidation of phenol using a carbon cloth-supported nickel-iron catalyst according to claim 1, characterized in that: In step 1, a 0.1-0.5 mol / L nickel nitrate aqueous solution is used as a deposition liquid, an Ag / AgCl electrode and a platinum sheet electrode are used as a reference electrode and a counter electrode, respectively, and the pretreated carbon cloth is used as a working electrode. Cyclic voltammetry is used to deposit nickel on the pretreated carbon cloth.

4. The method for preparing p-benzoquinone by selective electrocatalytic oxidation of phenol using a carbon cloth-supported nickel-iron catalyst according to claim 3, characterized in that: In step 1, cyclic voltammetry is used to scan 18 to 25 cycles in the range of -1.2 to 0.2 V at a scan rate of 4 to 6 mV / s to deposit nickel on the pretreated carbon cloth.

5. The method for preparing p-benzoquinone by selective electrocatalytic oxidation of phenol using a carbon cloth-supported nickel-iron catalyst according to claim 1, characterized in that: In step 1, the iron source is ferrous sulfate or ferrous chloride, and the nickel source is nickel nitrate or nickel sulfate.

6. The method for preparing p-benzoquinone by selective electrocatalytic oxidation of phenol using a carbon cloth-supported nickel-iron catalyst according to claim 1 or 5, characterized in that: In step 1, the mass ratio of the nickel source to the iron source is 1:9 to 9:1, and the concentration of the iron source in the ethanol aqueous solution containing the nickel source and the iron source is 0.1 to 0.5 mol / L.

7. The method for preparing p-benzoquinone by selective electrocatalytic oxidation of phenol using a carbon cloth-supported nickel-iron catalyst according to claim 6, characterized in that: In step 1, the volume ratio of ethanol to deionized water in the ethanol aqueous solution is 1:1 to 5:

1.

8. The method for preparing p-benzoquinone by selective electrocatalytic oxidation of phenol using a carbon cloth-supported nickel-iron catalyst according to claim 1, characterized in that: In step 2, the phenol concentration in the anolyte is 0.4-1.5 g / L, the KOH concentration is 1 mol / L, and the KOH concentration in the catholyte is 1 mol / L.

9. The method for selective electrocatalytic oxidation of phenol to p-benzoquinone using a carbon cloth-supported nickel-iron catalyst according to claim 8, characterized in that: In step 2, phenol is electrocatalytically oxidized at a constant potential of 0.5 to 0.9 V to prepare p-benzoquinone.

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