Carbon balance quantifying device and method based on phenol high-value conversion

Abstract

The invention discloses a carbon balance quantifying device and method based on phenol high-value conversion in the technical field of phenol manufacturing, the carbon balance quantifying device comprises an H-type electrolytic tank, a platinum sheet, a PtRu electrode, a power supply and a gas absorption device, the H-type electrolytic tank comprises a cathode chamber and an anode chamber, the lower end of the cathode chamber is communicated with one end of a hydrogen ion channel, and the other end of the cathode chamber is communicated with the other end of the hydrogen ion channel; the other end of the hydrogen ion channel is communicated with the lower end of the anode chamber, a proton exchange membrane for isolating the cathode chamber from the anode chamber is mounted in the hydrogen ion channel, and sealing covers are mounted at the tops of the cathode chamber and the anode chamber respectively; and the platinum sheet is arranged in the anode chamber. According to the method, a sealed H-type electrolytic tank with a gas adsorption device is adopted to capture the volatile product cyclohexane, meanwhile, a bimetallic PtRu electrode prepared through a cyclic electrodeposition method is evaluated, cyclohexane generated along with cyclohexanone and cyclohexanol is captured, meanwhile, the conversion rate of phenol and the Faraday efficiency of the product are effectively improved through the PtRu electrode, and therefore the quality of the product cyclohexane is improved. The carbon balance can be effectively recovered on the whole.

Description

Technical Field

[0001] This invention relates to the field of phenol manufacturing technology, specifically to a carbon balance quantitative device and method based on the high-value conversion of phenol. Background Technology

[0002] Currently, the main methods for treating phenol wastewater focus on pollutant removal. Among them, chemical oxidation aims to achieve complete mineralization, but it suffers from high reagent consumption and large greenhouse gas emissions. Although biological treatment methods are relatively environmentally friendly, they are usually difficult to effectively degrade phenol under practical conditions due to the toxicity of phenol and its inhibitory effect on microbial activity.

[0003] Electrocatalytic hydrogenation (ECH) of aqueous phenol to produce cyclohexanone and cyclohexanol can reduce pollutants and produce value-added chemicals, reflecting a shift in traditional treatment methods towards selectively converting pollutants into value-added products. Early studies on phenol wastewater treatment primarily relied on gas chromatography-mass spectrometry (GC-MS) to identify other potential products, easily overlooking the potential formation of highly volatile hydrogenation products. Furthermore, in existing preliminary experiments, the distribution of liquid-phase products often exhibits incomplete carbon balance, significantly increasing the difficulty of quantifying phenol conversion. Therefore, to accurately quantify all products, especially gaseous products, a dedicated gas absorption process needs to be integrated. Summary of the Invention

[0004] The purpose of this invention is to provide a quantitative carbon balance device and method based on the high-value conversion of phenol. By selectively electrocatalytically hydrogenating phenol with a PtRu electrode to prepare value-added products, the conversion rate and Faraday efficiency of phenol can be effectively improved, and the carbon balance can be effectively restored as a whole, promoting hydrogenation and subsequent C–O removal.

[0005] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a carbon balance quantitative device based on high-value conversion of phenol, comprising: The H-type electrolytic cell includes a cathode chamber and an anode chamber. The lower end of the cathode chamber is connected to one end of a hydrogen ion channel, and the other end of the hydrogen ion channel is connected to the lower end of the anode chamber. A proton exchange membrane for isolating the cathode chamber and the anode chamber is installed inside the hydrogen ion channel. Sealing caps are installed on the top of the cathode chamber and the anode chamber respectively. A platinum sheet is disposed inside the anode chamber, which is filled with a 0.1M H2SO4 solution, and the platinum sheet is completely or partially immersed in the 0.1M H2SO4 solution. The PtRu electrode is disposed inside the cathode chamber, which is filled with 0.1M H2SO4 solution and 25mM phenol solution. The PtRu electrode is completely or partially immersed in the mixed solution of 0.1M H2SO4 solution and 25mM phenol solution, and a gas cavity is formed between the liquid surface of the mixed solution and the inner top of the cathode chamber. A power supply, wherein the positive wire of the power supply is connected to one end of the platinum sheet, and the negative wire of the power supply is connected to one end of the PtRu electrode; A gas absorption device, wherein the top of the gas absorption device is connected to one end of a gas release channel, and the other end of the gas release channel is connected to the gas cavity.

[0006] As a further aspect of the present invention: the platinum sheet is the counter electrode, and the 0.1M H2SO4 solution is the anolyte.

[0007] As a further aspect of the present invention: the PtRu electrode is the working electrode, and the cathode solution is composed of 0.1M H2SO4 solution and 25mM phenol solution.

[0008] As a further aspect of the present invention: the top of the gas absorption device is connected to a gas injection channel, which is used to receive nitrogen, hydrogen and volatile products.

[0009] Secondly, the present invention provides a carbon balance quantitative method based on high-value conversion of phenol, applied to the carbon balance quantitative device based on high-value conversion of phenol as described above, the method comprising: The carbon fiber cloth was thoroughly cleaned, and a PtRu electrode was prepared on the cleaned carbon fiber cloth based on cyclic voltammetry (CV) electrodeposition technology. The prepared PtRu electrode was used as the working electrode, a platinum sheet was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. The H-type electrolytic cell was sealed, and a catholy solution consisting of 0.1M H2SO4 and 25mM phenol was injected into the cathode chamber. A 0.1M H2SO4 anolyte was injected into the anode chamber. The hydrogen ion channels were separated by a proton exchange membrane. A gas absorption device connected to the cathode chamber was set up, and decane was used as the gas absorption solvent in the gas absorption device. Nitrogen gas was introduced into the cathode chamber to initiate the electrocatalytic hydrogenation (ECH) reaction of phenol. A potential of -0.4V was applied, and the reaction was continued for 120 minutes. The cyclohexane collected in the gas absorption device was then quantitatively analyzed by GC-MS.

[0010] As a further aspect of the present invention: the GC-MS analysis method is a gas chromatography-mass spectrometry (GC-MS) analysis method, which is provided by a gas chromatography-mass spectrometry analyzer. The GC-MS analysis method is an analytical method that combines gas chromatography (GC) and mass spectrometry (MS) technologies.

[0011] As a further aspect of the present invention: the thorough cleaning of the carbon fiber cloth includes: The carbon fiber cloth was washed three times in sequence with acetone, ethanol and deionized water (DI water).

[0012] As a further aspect of the present invention: the fabrication of the PtRu electrode on cleaned carbon fiber cloth based on cyclic voltammetry (CV) electrodeposition technology includes: A solution of 5 mM H₂PtCl₆·6H₂O, 2 mM RuCl₃·3H₂O, and 0.5 M Na₂SO₄ was prepared and mixed to serve as the electrodeposition solution. The cyclic voltammetry was set with a cyclic scan period of 50 cycles, a potential range of -0.5 V to 1.7 V, and a scan rate of 100 mV / s to obtain the PtRu electrode; The PtRu electrode was cleaned with deionized water and then air-dried.

[0013] As a further aspect of the present invention: 0.5 M Na2SO4 solution is the supporting electrolyte of the electrodeposition solution.

[0014] As a further aspect of the present invention: the preparation of PtRu electrodes on cleaned carbon fiber cloth based on cyclic voltammetry (CV) electrodeposition technology also includes: Single-metal Pt / CC electrodes were synthesized using a 5mM Pt metal precursor solution, and single-metal Ru / CC electrodes were synthesized using a 5mM Ru metal precursor solution.

[0015] As a further aspect of the present invention: the proton exchange membrane is a Nafion 117 membrane.

[0016] As a further aspect of the present invention: using the prepared PtRu electrode as the working electrode includes: The morphology of the PtRu electrode was observed using field emission scanning electron microscopy (FESEM, ZEISS Sigma 300) and high-resolution transmission electron microscopy (HR-TEM, Tecnai F20). X-ray diffraction (XRD) analysis was performed on the PtRu electrode using an X-ray diffractometer, and X-ray photoelectron spectroscopy (XPS) analysis was performed on the PtRu electrode using an XPS. The loading of Pt and Ru elements in the PtRu electrode was quantitatively analyzed using inductively coupled plasma atomic emission spectrometry (ICP-AES, Thermo Scientific iCAP 7400). In-situ Fourier transform infrared (FTIR) spectra of the PtRu electrode were acquired using a mercury cadmium telluride (MCT) detector equipped with liquid nitrogen cooling.

[0017] As a further aspect of the present invention: the quantitative analysis of cyclohexane collected in the gas absorption device using GC-MS analysis includes: Set the initial temperature of the chromatographic column to 50°C, hold for 2 minutes, and then increase the temperature to 250°C at a rate of 15°C / min, while maintaining the temperature of the injection port and detector at 250°C. Sample 1: Phenol, cyclohexanone, and cyclohexanol were extracted from the cathode solution using ethyl acetate. Sample 2: Cyclohexane was absorbed by decane to obtain the extracted samples. The extracted samples were analyzed using gas chromatography (Agilent 8860) with a flame ionization detector (FID) and an HP-5 capillary column (0.25 μm × 0.32 mm × 30 m). Calculate the carbon balance percentage.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention captures the volatile product cyclohexane using a sealed H-type electrolytic cell equipped with a gas adsorption device. At the same time, it evaluates the use of a bimetallic PtRu electrode prepared by cyclic electrodeposition to capture cyclohexane generated together with cyclohexanone and cyclohexanol. The PtRu electrode effectively improves the conversion rate and Faradaic efficiency of phenol, thus effectively restoring the carbon balance as a whole, promoting hydrogenation and subsequent C–O removal, and bridging the long-standing selectivity / carbon balance gap in the electrocatalytic hydrogenation of phenol.

[0019] 2. This invention synthesizes PtRu bimetallic electrodes based on cyclic electrodeposition, which can accurately quantify the products of the phenol conversion reaction, thereby effectively improving the conversion rate and high Faradaic efficiency of phenol, while exhibiting excellent selectivity. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the electrocatalytic hydrogenation (ECH) of phenol catalyzed by the PtRu catalyst of the present invention; Figure 2 a-2c are SEM images of the PtRu electrode at different magnifications according to the present invention. Figure 2 d-2e are EDS images of Pt and Ru in the PtRu electrode of this invention. Figure 2 f is an HR-TEM image of the PtRu electrode of the present invention. Figure 2 g represents the XRD patterns of the Pt, PtRu, and Ru electrodes of this invention. Figure 2 h-2i is the XPS spectrum of Pt 4f and Ru 3d in the PtRu electrode of the present invention; Figure 3 a is a graph showing the changes in the concentrations of phenol and liquid products over time during electrocatalytic hydrogenation (ECH) using a PtRu electrode (without an absorption device). Figure 3 b is a graph showing the changes in product selectivity and carbon balance over time during the ECH process; Figure 3 c is the GC-MS mass spectrometry fragmentation diagram of the captured gaseous products; Figure 3 d is a graph showing the effect of the gas absorption device on the electrocatalytic hydrogenation performance of phenol; Figure 4 a is the LSV curve of the PtRu electrode with and without 25 mM phenol in 0.1M H2SO4; Figure 4 b is the LSV curve of different electrodes in 0.1M H2SO4 with 25 mM phenol added; Figure 4 c represents the Tafel slope diagram of different electrodes when 25 mM phenol is added to 0.1M H2SO4; Figure 4 d represents the C obtained by cyclic voltammetry (CV) for different electrodes in 0.1 M H₂SO₄. dl Values, representing relative electrochemical surface area plots; Figure 5 a) is a comparison of phenol conversion and FE product after 120 minutes of electrolysis using different electrodes; Figure 5 b is a graph showing the effect of the application potential on the phenol conversion and product FE after 60 minutes of electrolysis using a PtRu electrode. Figure 5 c is a graph showing the changes in the concentrations of phenol and hydrogenation products in the ECH system using a PtRu electrode; Figure 5 d is a graph showing the relationship between reaction time and product FE during the ECH process using a PtRu electrode; Figure 5 e represents the stability test results of the PtRu electrode after ten consecutive ECH cycles; Figure 5 f is a graph showing the effect of common interfering substances on the ECH properties of phenol.

[0021] Figure 6 a represents the d-band center diagram of the calculated Pt(111) and PtRu(111); Figure 6 b shows the results of phenol on Pt and PtRu, indicating stronger electron transfer on PtRu; Figure 6 c is a schematic diagram showing the stepwise hydrogenation reaction of phenol in situ on a PtRu electrode at different potentials; Figure 6 d is a schematic diagram of the proposed ECH reaction pathway for phenol; Figure 7 This is a diagram illustrating the method steps of the present invention.

[0022] In the diagram: 1. Platinum sheet; 2. PtRu electrode; 3. Power supply; 4. Gas absorption device; 5. Cathode chamber; 6. Anode chamber; 7. Hydrogen ion channel; 8. Proton exchange membrane; 9. Sealing cap; 10. Carbon fiber cloth. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example: like Figure 1 As shown, this invention provides a carbon balance quantitative device based on the high-value conversion of phenol, including an H-type electrolytic cell, a platinum sheet 1, a PtRu electrode 2, a power supply 3, and a gas absorption device 4. The H-type electrolytic cell includes a cathode chamber 5 and an anode chamber 6. The lower end of the cathode chamber 5 is connected to one end of a hydrogen ion channel 7, and the other end of the hydrogen ion channel is connected to the lower end of the anode chamber. A proton exchange membrane 8 is installed inside the hydrogen ion channel to isolate the cathode chamber and the anode chamber. Sealing caps 9 are installed on the top of the cathode chamber and the anode chamber, respectively. The platinum sheet is placed inside the anode chamber, which is filled with 0.1M H2SO4 solution, and the platinum sheet is completely or partially immersed in the 0.1M H2SO4 solution. The PtRu electrode is placed inside the cathode chamber, which is filled with 0.1M H2SO4 solution and 25mM phenol solution, and the PtRu electrode is completely or partially immersed in the 0.1M H2SO4 solution. In a mixed solution consisting of H2SO4 solution and 25mM phenol solution, a gas cavity is formed between the liquid surface of the mixed solution and the inner top of the cathode chamber; the positive electrode wire of the power supply is connected to one end of the platinum plate, and the negative electrode wire of the power supply is connected to one end of the PtRu electrode; the top of the gas absorption device is connected to one end of the gas release channel, and the other end of the gas release channel is connected to the gas cavity.

[0025] In this embodiment, a platinum sheet is used as the counter electrode, a 0.1M H2SO4 solution is used as the anolyte, a PtRu electrode is used as the working electrode, and a 0.1M H2SO4 solution and a 25mM phenol solution are used as the catholyte. The top of the gas absorption device is connected to a gas injection channel, which is used to receive nitrogen, hydrogen and volatile products.

[0026] Preferably, the carbon fiber cloth has an area of ​​2cm × 2cm, and the platinum sheet has an area of ​​2cm × 2cm.

[0027] like Figure 7 As shown, this invention provides a carbon balance quantitative method based on high-value conversion of phenol, applied to the carbon balance quantitative device based on high-value conversion of phenol as described above. The method includes the following steps: S1: Thoroughly clean the carbon fiber cloth 10, and prepare a PtRu electrode 2 on the cleaned carbon fiber cloth 10 based on CV electrodeposition technology. Use the prepared PtRu electrode 2 as the working electrode, use a platinum sheet 1 as the counter electrode, and use an Ag / AgCl electrode as the reference electrode. S2: The H-type electrolytic cell is sealed, and a catholy solution consisting of 0.1M H2SO4 and 25mM phenol is injected into the cathode chamber 5. A 0.1M H2SO4 anolyte is injected into the anode chamber 6. The hydrogen ion channel 7 is separated by a proton exchange membrane 8. A gas absorption device 4 connected to the cathode chamber 5 is set up, and decane is used as the gas absorption solvent in the gas absorption device 4. S3: Nitrogen gas is introduced into cathode chamber 5 to start the ECH reaction process of phenol. A potential of -0.4V is applied and the reaction is continued for 120 minutes. Then, cyclohexane collected in gas absorption device 4 is quantitatively analyzed by GC-MS.

[0028] In this embodiment, before preparing the PtRu electrode, the carbon fiber cloth was thoroughly cleaned three times sequentially with acetone, ethanol, and deionized water (DI water). The PtRu electrode was prepared in a three-electrode system using cyclic electrodeposition. A carbon cloth (2 cm × 2 cm) served as the working electrode, a platinum sheet (2 cm × 2 cm) as the counter electrode, and an Ag / AgCl electrode (saturated KCl) as the reference electrode. The electrodeposition solution contained 5 mM H₂PtCl₆·6H₂O, 2 mM RuCl₃·3H₂O, and 0.5 M Na₂SO₄ as the supporting electrolyte. Electrodeposition was performed for 50 cycles using cyclic voltammetry (CV) at a potential range of -0.5 to 1.7 V relative to the Ag / AgCl electrode and a scan rate of 100 mV / s. After deposition, the PtRu electrode was washed with DI water and air-dried. For comparison, single-metal Pt / CC and Ru / CC electrodes were synthesized under the same conditions using 5 mM solutions of the corresponding metal precursors.

[0029] Preferably, the electrode proton exchange membrane is a Nafion 117 membrane.

[0030] In this embodiment, the prepared PtRu electrode was used as the working electrode for electrode characterization. The morphology of the prepared PtRu electrode was observed using field emission scanning electron microscopy (FESEM, ZEISS Sigma 300) and high-resolution transmission electron microscopy (HR-TEM, Tecnai F20). X-ray diffraction (XRD) analysis was performed using a Rigaku SmartLab SE X-ray diffractometer (Japan). X-ray photoelectron spectroscopy (XPS) measurements were performed using a Thermo Scientific K-Alpha instrument. The loading amounts of Pt and Ru elements were quantitatively analyzed using inductively coupled plasma atomic emission spectrometry (ICP-AES, Thermo Scientific iCAP 7400). In-situ Fourier transform infrared spectroscopy (FTIR) was performed using a Thermo Scientific Nicolet 8700 equipped with a liquid nitrogen-cooled mercury cadmium telluride (MCT) detector.

[0031] In this embodiment, the electrocatalytic hydrogenation (ECH) of phenol was carried out in an H-type cell using a three-electrode system separated by a Nafion 117 membrane. A PtRu electrode (2 cm × 2 cm) was used as the working electrode, a platinum sheet (2 cm × 2 cm) as the counter electrode, and an Ag / AgCl electrode (saturated KCl) as the reference electrode. The catholyte consisted of 0.1 M H₂SO₄ and 25 mM phenol, and the anolyte contained 0.1 M H₂SO₄. Unless otherwise specified, all experiments were repeated three times, and the results are reported as mean and standard deviation.

[0032] Ethyl acetate was used to extract phenol and its products. The extracted samples were analyzed by gas chromatography (Agilent 8860) with a flame ionization detector (FID) and an HP-5 capillary column (0.25 μm × 0.32 mm × 30 m). The injection port and detector temperatures were maintained at 250°C. Sample 1 was analyzed using ethyl acetate to extract phenol, cyclohexanone, and cyclohexanol from the cathode solution; Sample 2 was analyzed using cyclohexane absorbed by decane. The column was initially heated to 50°C for 2 minutes, then increased to 250°C at a rate of 15°C / min. The conversion (%), selectivity (%), yield (%), and production rate (mmol / cm²) of phenol were recorded. -2 h -1 The calculation of Faraday efficiency (FE%), as well as products (cyclohexanone, cyclohexanol, and cyclohexane) and carbon balance (%), is performed using the following formula:

[0033]

[0034]

[0035]

[0036]

[0037]

[0038] Where t represents the reaction time (hours), A represents the electrode area (square centimeters), Q represents the total charge transferred through the circuit (coulombs), F is the Faraday constant (96485.3 coulombs / molar), and n is the number of electrons involved in the formation of the product (4 for cyclohexanone, 6 for cyclohexanol, and 8 for cyclohexane).

[0039] In this embodiment, electrochemical measurements were performed using a CHI750E electrochemical workstation in a standard three-electrode system. A pre-prepared PtRu electrode (1 cm × 1 cm) was used as the working electrode, a platinum sheet (1 cm × 1 cm) as the counter electrode, and an Ag / AgCl (saturated KCl) electrode as the reference electrode. The measured potentials were converted to the reversible hydrogen electrode (RHE) scale according to the Nernst equation:

[0040] LSV measurements were performed in 0.1 M H₂SO₄ with and without 25 mM phenol, using a scan rate of 5 mV / s and 85% iR compensation. CV measurements were performed in the non-Radida region in 0.1 M H₂SO₄ to calculate the double-layer capacitance (C0). dl The capacitor was used to determine the electrochemical surface area (ECSA) of the prepared electrode. Electrochemical impedance spectroscopy (EIS) was performed at a potential of -0.05 V vs RHE, with a frequency range from 100 kHz to 0.1 Hz and an amplitude of 5 mV. The test solution was 0.1 M H2SO4 containing 25 mM phenol.

[0041] In this embodiment, the ECH electrode was characterized as follows: the PtRu electrode was prepared on carbon cloth by cyclic electrodeposition within a potential range of -0.5 to 1.7 V vs Ag / AgCl. To achieve optimal performance in the electrocatalytic hydrogenation of phenol (ECH), the loading of Pt and Ru was adjusted by regulating the molar ratio of the precursors while keeping the platinum salt concentration at 5 mM. The optimal molar ratio for electrodeposition was determined to be 5:2.

[0042] like Figure 2 As shown in Figure ac, SEM images at different magnifications reveal that the deposited metal nanoparticles uniformly cover the carbon cloth fibers, forming an interconnected structure that provides abundant active sites and facilitates efficient mass transport.

[0043] like Figure 2 As shown in the diagram, energy dispersive spectroscopy (EDS) mapping further confirmed the uniform distribution of Pt and Ru elements on the surface. Quantitative EDS analysis revealed a Pt:Ru surface atomic ratio of 10.9:1, highly consistent with results obtained by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Transmission electron microscopy (TEM) images of the PtRu deposits showed spherical nanoclusters assembled from smaller nanoparticles, while high-resolution TEM (HR-TEM) identified a lattice spacing of 0.226 nm for Pt(111). Figure 2 As shown in f, the lattice spacing of RuO2(111) is 0.222 nm, indicating that Pt 0 Pt and RuO2 are the main crystalline phases. According to ICP-AES, the loadings of Pt and Ru are 1.068 and 0.057 mg / cm³, respectively. 2 The relatively low Ru content is likely due to the oxidation-dissolution process that occurs during electrodeposition.

[0044] like Figure 2 As shown in g, the X-ray diffraction (XRD) pattern reveals that the crystal phase of Pt in the PtRu electrode is consistent with that of metallic Pt (PDF04-0802). Diffraction peaks at approximately 40°, 46°, and 68° correspond to the (111), (200), and (220) crystal planes of the face-centered cubic (fcc) structure of Pt, respectively. However, no phases similar to Ru or RuO were observed. x The presence of distinct diffraction peaks is likely due to the low Ru content. Based on XRD results and high-resolution TEM (HR-TEM) analysis, it can be inferred that the presence of RuO2 has minimal impact on the crystal structure of Pt.

[0045] X-ray photoelectron spectroscopy (XPS) was further employed to investigate the chemical states of Pt and Ru in the PtRu electrode. Figure 2 As shown in h, the deconvolution spectrum of the Pt 4f region exhibits two double peaks: the peaks at 71.1 eV and 74.3 eV are attributed to Pt, respectively. 0 4f 7 / 2 and Pt 0 4f 5 / 2 The peak values ​​at 72.3 eV and 75.5 eV correspond to Pt. 2+ 4f 7 / 2 and Pt 2+ 4f 5 / 2 For Ru, such as Figure 2 As shown in i, the 3p after deconvolution... 3 / 2 The spectrum shows two distinct peaks, at 462.1 eV and 465.2 eV, which are attributed to Ru. 0 and Ru4+ Pt 0 Ru 0 The coexistence of RuO2 indicates the formation of bimetallic interface sites, which is expected to enhance adsorption and electronic interactions.

[0046] In this embodiment, at a cathode potential of -0.40 V vs Ag / AgCl, the reaction lasted for 120 minutes, during which the concentration of phenol gradually decreased from 25 mM to near 0 mM. In contrast, the concentration of cyclohexanone remained below 1.5 mM throughout. Figure 3 The concentration of cyclohexanol (as shown in figure a) steadily increased to approximately 15 mM. GC-MS analysis (after ethyl acetate extraction) detected only these two products. However, the overall product selectivity for cyclohexanone and cyclohexanol remained stable at approximately 62%, far below the theoretical value of 100%. Meanwhile, as... Figure 3 As shown in b, the carbon balance gradually decreased, from about 90% at 30 minutes to about 62% at 120 minutes.

[0047] The observed carbon loss was initially assumed to be due to random error or experimental uncertainty. This prompted us to explore other possible factors—including volatilization, electronic adsorption, membrane crosstalk, and measurement error—which ultimately proved to be insignificant. Although this was a misguided step, it was an important and necessary process of elimination.

[0048] In this embodiment, while addressing the selectivity and carbon balance gap through gas-phase cyclohexane detection, the volatility of phenol, cyclohexanone, and cyclohexanol was tested using controlled stirring experiments, but no significant loss was observed. Secondly, the possibility of organic matter adsorbing onto the electrode surface was ruled out using specialized adsorption tests. Thirdly, the possibility of organic matter crossing into the anode chamber via the Nafion N117 membrane was ruled out, as no organic matter was detected in the anode electrolyte. Fourthly, repeated recalibration of the GC standard curve eliminated the possibility of quantitative error. Finally, nitrogen purging experiments confirmed that dissolved oxygen did not affect the electrocatalytic hydrogenation of phenol on the PtRu electrode. Despite these controls, the post-reaction total organic carbon (TOC) measurement consistently decreased, indicating the possible formation of unidentified products, possibly due to degradation or conversion into volatile organic compounds. This unresolved carbon loss constitutes a critical obstacle to further analysis and highlights the urgent need for a more comprehensive product detection strategy.

[0049] like Figure 1 As shown, the reactor was sealed, and the cathode chamber was connected to a gas absorption device (n-decane trap), with continuous nitrogen purging. Under these conditions, volatile products were captured and analyzed. Figure 3As shown in c, the mass spectrometry results indicate that the mass-to-charge ratio of the sample is highly consistent with that of the cyclohexane standard, confirming the formation of cyclohexane. After complete conversion of phenol during the ECH process, cyclohexane accounts for approximately 32% of the product, with the remainder being cyclohexanone and cyclohexanol; as... Figure 3 As shown in d, when this gaseous component is taken into account, the overall carbon balance is restored to over 95%.

[0050] These results address the long-standing selectivity / carbon balance discrepancy of Pt-based catalysts in acidic media and highlight a methodological importance: without sealed operation and gas trapping, volatile products (e.g., cyclohexane) are systematically underestimated, leading to an underestimation of selectivity and Faraday efficiency in the electrocatalytic hydrogenation of phenol.

[0051] In this embodiment, the intrinsic activity of PtRu was initially assessed by LSV tests in 0.1M H2SO4 electrolyte with and without (HER) 25mM phenol. Figure 4 As shown in figure a, the onset potential of phenol electrocatalytic hydrogenation (-0.20 V vs Ag / AgCl) is more negative than that of the hydrogen evolution reaction (HER) (-0.25 V vs Ag / AgCl), indicating that phenol reduction is more favorable than HER on the PtRu electrode. Next, the ECH activity of different electrodes was investigated. At the same potential (-0.40 V vs Ag / AgCl), as... Figure 4 As shown in b, the PtRu electrode exhibits a significantly higher electrocatalytic hydrogenation current density for phenol than the Pt or Ru electrode. Figure 4 As shown in c, kinetic analysis supports this trend: the calculated Tafel slope of PtRu is 79.4 mV / dec, which is significantly lower than that of Pt (86.5 mV / dec) and Ru (129.1 mV / dec), indicating that the PtRu electrode has enhanced reaction kinetics.

[0052] EIS measurements showed that PtRu had the lowest charge transfer resistance among the tested samples, consistent with Tafel's results. To evaluate the available surface sites for different electrodes, such as... Figure 4 As shown in Figure d, the electric double-layer capacitance (Cdl) was determined by cyclic voltammetry (CV) tests at different scan rates. The PtRu electrode exhibited the highest Cdl value (21.14 mF / cm). 2 ), greater than Pt (18.87 mF / cm 2 ) and Ru (16.90 mF / cm 2 This indicates that it has a larger electrochemical surface area. These results demonstrate that the prepared PtRu electrode exhibits excellent electrocatalytic hydrogenation activity and kinetic characteristics for phenol.

[0053] Then, in a sealed H-type battery, as Figure 5 As shown in Figure a, a practical performance benchmark test was conducted for 120 minutes using an optimized potential (-0.40 V vs Ag / AgCl). The original carbon cloth showed almost no phenol conversion efficiency within 120 minutes. In contrast, the Pt cathode showed a significant improvement in phenol conversion (45.7%), but the Faraday efficiency (FE) of the product was extremely low (29.4%). This result is mainly attributed to the strong competition from the hydrogen evolution reaction (HER), which consumes the surface-adsorbed hydrogen atoms (H₂O₃). ads For the Ru electrode, the phenol conversion efficiency and product FE were only 1.9% and 11.6%, respectively. The lower phenol conversion efficiency of the Ru electrode can be attributed to the relatively low Ru loading on the carbon cloth substrate. Furthermore, the PtRu electrode achieved a simultaneous increase in phenol conversion (98.9%) and total product FE (59.5%), while the physical adsorption of phenol / product on the electrode was almost negligible. The product FE obtained using the PtRu electrode exceeded the sum of the FEs tested for the Pt and Ru electrodes separately, confirming a synergistic enhancement effect between Pt and RuO2 / Ru in the bimetallic electrode. Compared to the Pt (38.7%) and Ru (1.31%) electrodes, the PtRu electrode exhibited the highest yield (90.5%), indicating that the PtRu electrode possesses excellent catalytic activity.

[0054] During the 60-minute reaction, such as Figure 5 As shown in b, the potential dependence of the reaction is applied. As the potential becomes more negative, the conversion of phenol continues to increase; however, the Faradaic efficiency (FE) of cyclohexanone steadily decreases. Simultaneously, due to competition from the hydrogen evolution reaction (HER) at higher overpotentials, the total FE of the product continuously decreases from 70% to 50%. At a cathode potential of -0.40 V vs Ag / AgCl, as... Figure 5 As shown in Figure c, a steady accumulation of cyclohexane concentration was observed, reaching approximately 7.9 mM at 120 minutes. Figure 5 As shown in Figure d, the PtRu electrode reached its maximum total electron efficiency (FE) (66.5%) during the reaction, indicating its high electron utilization efficiency under optimal conditions. The effect of initial electrolyte pH on electrocatalytic hydrogenation (ECH) performance was also investigated. The catalytic activity of the PtRu electrode decreased significantly under neutral conditions and was almost completely inhibited in alkaline media. This significant effect indicates that proton concentration plays a crucial role in driving the hydrogenation of phenol. The durability of PtRu was further evaluated by conducting ten consecutive cycles of testing under the same conditions. Figure 5 As shown in Figure e, no significant loss of activity was observed. The yield remained at 110 µmol / cm³. 2 / h, highlighting the excellent operational stability of the system. To evaluate its practical applicability, the PtRu electrode was subjected to common interfering substances (Cl... -NO3 - NH4 + ECH performance tests were also conducted in the presence of CH3OH, substances commonly found in industrial phenol wastewater. The results showed that these substances had a relatively small impact on phenol conversion. Figure 5 As shown in f, the PtRu electrode exhibits excellent selectivity and anti-interference capabilities. Post-reaction SEM, TEM, XRD, and XPS analyses revealed that the used PtRu retained its morphology, crystal structure, and surface composition, confirming its robust structural and chemical stability during operation.

[0055] In this embodiment, density functional theory (DFT) calculations were performed to elucidate the catalytic behavior of the PtRu electrode. Figure 6 As shown in figure a, the d-band center of PtRu (-1.285 eV) is closer to the Fermi level than that of bare Pt (-1.663 eV). Since a less negative d-band center typically enhances the interaction between the metal d-state and the adsorbate, it strengthens the adsorption force and lowers the energy barrier for bond activation. Consistent with this expectation, phenol adsorption on PtRu is slightly stronger than on Pt, with adsorption energies of -3.17 eV and -3.10 eV, respectively. Charge density difference analysis shows that the amount of electrons transferred from PtRu to adsorbed phenol (0.46 eV) is significantly greater than that on Pt. - The amount of electrons transferred from Pt to phenol is greater than 0.37 e. - ),like Figure 6 As shown in b, the enhanced metal-adsorbate interaction on PtRu is beneficial for the first hydrogenation step.

[0056] like Figure 6 As shown in Figure c, potential-dependent in-situ Fourier transform infrared (FTIR) spectroscopy was used to track reaction intermediates adsorbed on the catalyst surface during electrolysis. When the potential was gradually changed from -0.10 V to -0.40 V vs Ag / AgCl, the reaction intermediate at 1640 cm⁻¹... -1 The intensity of the band (C=O stretching vibration of ketone substances, such as cyclohexanone) increases, and at approximately 3350 cm⁻¹... -1 The wide OH stretching bands (cyclohexanol and phenol) are also enhanced. Meanwhile, 1198 cm⁻¹ -1 (CO vibration of phenol-OH) and 1495 cm -1 The intensity of the (aromatic C=C) band is weakened, which is consistent with the hydrogenation of the ring and the transformation of the phenolic group.

[0057] To test the important role of liquid products in cyclohexane formation, we conducted electrolysis experiments on cyclohexanone and cyclohexanol separately (25 mM substrate, 0.1 M H₂SO₄, -0.40 V vs Ag / AgCl, 120 min). As shown in Table 1, cyclohexanone was almost completely converted (99.5%) to cyclohexanol, with small amounts of cyclohexane formed (selectivity 91.8% and 7.4%, respectively). In contrast, under similar conditions, approximately 32% of the product from the ECH reaction of phenol was cyclohexane. Cyclohexanol showed almost no reaction (conversion 0.4%), with no cyclohexane formation. These results indicate that cyclohexanone and cyclohexanol are not the major precursors for cyclohexane in our aqueous ECH system. Combined with FTIR spectroscopy results, a reaction pathway was also hypothesized in which a partially hydrogenated enone intermediate (e.g., cyclohex-3-enone) is formed directly from phenol, followed by a deoxygenation reaction to generate cyclohexane. This hypothesis is consistent with the following viewpoints: (i) theoretical studies show that the aqueous hydrogenation of phenol is converted to cyclohexanone via cyclohex-3-enone as an intermediate; (ii) DFT calculations show that the deoxygenation reaction of partially hydrogenated phenol is more energy-efficient than the deoxygenation reaction of cyclohexanol or cyclohexanone.

[0058] Based on this Figure 6 The mechanism proposed in d is as follows: PtRu enhances the adsorption and electron transfer of phenol, promoting the early cyclohydrogenation reaction to generate ketone / enone species; subsequently, there are two competing pathways—further hydrogenation to generate cyclohexanol, and deoxygenation of the enone to generate cyclohexane. Pt 0 and Ru 0 The coexistence of / RuO2 may modulate the adsorption energy and interfacial electron density, thereby promoting hydrogenation and selective removal of CO bonds at the applied potential.

[0059] Table 1 shows the ECH reactions of cyclohexanone and cyclohexanol with the PtRu electrode.

[0060] Reaction conditions: 40 mL 0.1 M H2SO4 solution, 25 mM cyclohexanone or cyclohexanol added, -0.40 V vs Ag / AgCl, 120 minutes.

[0061] In this embodiment, a hybrid PtRu electrode was successfully synthesized for the efficient electrocatalytic hydrogenation (ECH) of aqueous phenol at ambient temperature and pressure, generating value-added products such as cyclohexanol and cyclohexane. By using a sealed H-type cell and combining it with a solvent trap to capture the volatile product cyclohexane, the long-standing carbon balance deficit was compensated by quantitatively capturing cyclohexane generated alongside cyclohexanone and cyclohexanol. Under optimized conditions, the PtRu electrode exhibited a phenol conversion rate of 98.9%, a significant Faradaic efficiency (FE) of 66.5%, and a cyclohexane selectivity of approximately 32%, restoring the overall carbon balance to >95%. The system demonstrated excellent stability during 10 consecutive cycles and maintained good performance in the presence of common coexisting species, highlighting its practical robustness in phenol wastewater treatment. Compared to Pt alone, PtRu enhanced phenol adsorption and interfacial electron transfer, promoting phenol activation and subsequent hydrogenation reactions. Overall, a reliable quantitative ECH analysis method was established by combining gas trapping with conventional liquid analysis. (ii) A highly selective and robust PtRu electrode was demonstrated, capable of efficiently converting phenol to cyclohexanol and cyclohexane. The combined methodological and material advancements provide a clear pathway for accurate product accounting and resource-oriented treatment of phenol wastewater.

[0062] In this embodiment, the reagents include phenol, chloroplatinic acid hexahydrate, rhodium chloride, sodium sulfate, and sulfuric acid. The phenol is 99.0% pure C6H6O, the chloroplatinic acid hexahydrate is H2PtCl6·6H2O with a Pt mass percentage ≥37.5%, the ruthenium chloride is RuCl3·3H2O with a purity of 98.0%, the sodium sulfate is Na2SO4 with a purity of 99.0%, and the sulfuric acid is H2SO4 with a purity of 95.0%-98.0%. All reagents are used as is without further purification, and all aqueous solutions have a resistivity exceeding 18.2 MΩ·cm. -1 Deionized water.

[0063] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A carbon balance quantitative device based on high-value conversion of phenol, characterized in that... ,include: The H-type electrolytic cell includes a cathode chamber and an anode chamber. The lower end of the cathode chamber is connected to one end of a hydrogen ion channel, and the other end of the hydrogen ion channel is connected to the lower end of the anode chamber. A proton exchange membrane for isolating the cathode chamber and the anode chamber is installed inside the hydrogen ion channel. Sealing caps are installed on the top of the cathode chamber and the anode chamber respectively. A platinum sheet is disposed inside the anode chamber, which is filled with a 0.1M H2SO4 solution, and the platinum sheet is completely or partially immersed in the 0.1M H2SO4 solution. The PtRu electrode is disposed inside the cathode chamber, which is filled with 0.1M H2SO4 solution and 25mM phenol solution. The PtRu electrode is completely or partially immersed in the mixed solution of 0.1M H2SO4 solution and 25mM phenol solution, and a gas cavity is formed between the liquid surface of the mixed solution and the inner top of the cathode chamber. A power supply, wherein the positive wire of the power supply is connected to one end of the platinum sheet, and the negative wire of the power supply is connected to one end of the PtRu electrode; A gas absorption device, wherein the top of the gas absorption device is connected to one end of a gas release channel, and the other end of the gas release channel is connected to the gas cavity.

2. The carbon balance quantitative device based on high-value conversion of phenol according to claim 1, characterized in that: The platinum sheet is the counter electrode, and the 0.1M H2SO4 solution is the anolyte.

3. The carbon balance quantitative device based on high-value conversion of phenol according to claim 2, characterized in that: The PtRu electrode is the working electrode, and the catholy solution consists of 0.1M H2SO4 solution and 25mM phenol solution.

4. The carbon balance quantitative device based on high-value conversion of phenol according to claim 3, characterized in that: The top of the gas absorption device is connected to a gas injection channel, which is used to receive nitrogen, hydrogen and volatile products.

5. A carbon balance quantitative method based on high-value conversion of phenol, applied to the carbon balance quantitative device based on high-value conversion of phenol as described in claim 4, characterized in that... The method includes: The carbon fiber cloth was thoroughly cleaned, and a PtRu electrode was prepared on the cleaned carbon fiber cloth based on cyclic voltammetry electrodeposition technology. The prepared PtRu electrode was used as the working electrode, a platinum sheet was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. The H-type electrolytic cell was sealed, and a catholy solution consisting of 0.1M H2SO4 and 25mM phenol was injected into the cathode chamber. A 0.1M H2SO4 anolyte was injected into the anode chamber. The hydrogen ion channels were separated by a proton exchange membrane. A gas absorption device connected to the cathode chamber was set up, and decane was used as the gas absorption solvent in the gas absorption device. Nitrogen gas was introduced into the cathode chamber to initiate the electrocatalytic hydrogenation reaction of phenol. A potential of -0.4V was applied, and the reaction was continued for 120 minutes. The cyclohexane collected in the gas absorption device was then quantitatively analyzed by GC-MS.

6. The carbon balance quantitative method based on high-value conversion of phenol according to claim 5, characterized in that: The thorough cleaning of the carbon fiber cloth includes: The carbon fiber cloth was washed three times in sequence with acetone, ethanol and deionized water.

7. The carbon balance quantitative method based on high-value conversion of phenol according to claim 6, characterized in that: The fabrication of PtRu electrodes on cleaned carbon fiber cloth based on cyclic voltammetry electrodeposition technology includes: A solution of 5 mM H₂PtCl₆·6H₂O, 2 mM RuCl₃·3H₂O, and 0.5 M Na₂SO₄ was prepared and mixed to serve as the electrodeposition solution. The cyclic voltammetry was set with a cyclic scan period of 50 cycles, a potential range of -0.5 V to 1.7 V, and a scan rate of 100 mV / s to obtain the PtRu electrode; The PtRu electrode was cleaned with deionized water and then air-dried.

8. The carbon balance quantitative method based on high-value conversion of phenol according to claim 5, characterized in that: The proton exchange membrane is a Nafion 117 membrane.

9. The carbon balance quantitative method based on high-value conversion of phenol according to claim 5, characterized in that: The step of using the prepared PtRu electrode as the working electrode includes: The morphology of the PtRu electrode was observed using field emission scanning electron microscopy and high-resolution transmission electron microscopy. X-ray diffraction analysis and X-ray photoelectron spectroscopy analysis of the PtRu electrode were performed using an X-ray diffractometer and an X-ray photoelectron spectroscopy (XPS) instrument. The loading of Pt and Ru elements in a PtRu electrode was quantitatively analyzed by inductively coupled plasma atomic emission spectrometry. In-situ Fourier transform infrared spectra of the PtRu electrode were acquired using a mercury cadmium telluride detector equipped with liquid nitrogen cooling.

10. The carbon balance quantitative method based on high-value conversion of phenol according to claim 9, characterized in that: The quantitative analysis of cyclohexane collected in the gas absorption device using GC-MS includes: Set the initial temperature of the chromatographic column to 50°C, hold for 2 minutes, and then increase the temperature to 250°C at a rate of 15°C / min, while maintaining the temperature of the injection port and detector at 250°C. Sample 1: Phenol, cyclohexanone, and cyclohexanol were extracted from the cathode solution using ethyl acetate; Sample 2: Cyclohexane was absorbed by decane to obtain the extracted sample, which was analyzed by gas chromatography with flame ionization detector and HP-5 capillary column. Calculate the carbon balance percentage.

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