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

Abstract

The application discloses a kind of carbon balance quantitative device and method based on phenol high-value conversion in the technical field of phenol manufacturing, including H-type electrolytic cell, platinum sheet, PtRu electrode, power supply and gas absorption device, H-type electrolytic cell includes cathode chamber and anode chamber, the lower end of cathode chamber is communicated with the one end of hydrogen ion channel, the other end of hydrogen ion channel is communicated with the lower end of anode chamber, the inside of hydrogen ion channel is installed with proton exchange membrane for isolating cathode chamber and anode chamber, the top of cathode chamber and anode chamber is respectively installed sealing cover;Platinum sheet is arranged in the inside of anode chamber.The application captures volatile product cyclohexane by using sealed H-type electrolytic cell with gas adsorption device, while evaluating bimetallic PtRu electrode prepared by cyclic electrodeposition method, cyclohexane generated together with cyclohexanone and cyclohexanol is captured, while the conversion rate of phenol and product faradaic efficiency are effectively improved by PtRu electrode, and carbon balance can be effectively restored as a whole.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of phenol manufacturing, and particularly relates to a carbon balance quantification device and method based on high-value conversion of phenol. BACKGROUND

[0002] At present, the treatment method of phenol wastewater mainly focuses on the removal of pollutants. Among them, the chemical oxidation method aims to achieve complete mineralization, but the chemical oxidation method has the problems of high reagent consumption and large greenhouse gas emission; the biological treatment method is relatively environmentally friendly, but due to the toxicity of phenol and its inhibition on microbial activity, it is usually difficult to effectively degrade phenol under actual conditions.

[0003] Electrocatalytic hydrogenation (ECH) of aqueous phenol to produce cyclohexanone and cyclohexanol can not only reduce pollutants, but also produce value-added chemicals, and the traditional treatment method is gradually changing to selectively convert pollutants into value-added products. In the early study of phenol wastewater treatment, the existence of other potential products is mainly identified by gas chromatography-mass spectrometry (GC-MS), which is easy to overlook the potential formation process of highly volatile hydrogenation products. On the other hand, in the existing preliminary experiments, the distribution of liquid phase products often has the problem of incomplete carbon balance, which greatly increases the difficulty of phenol conversion quantification. Therefore, in order to accurately quantify all products, especially gaseous products, a special gas absorption process needs to be integrated. SUMMARY

[0004] The purpose of the present application is to provide a carbon balance quantification device and method based on high-value conversion of phenol, which can effectively improve the conversion rate and Faraday efficiency of phenol by selectively electrocatalytically hydrogenating phenol based on a PtRu electrode to prepare value-added products, and can effectively restore the carbon balance as a whole, promoting hydrogenation and subsequent C-O removal.

[0005] To achieve the above purpose, the present application provides the following technical scheme:

[0006] In a first aspect, the present application provides a carbon balance quantification device based on high-value conversion of phenol, comprising:

[0007] An H-type electrolytic cell, the H-type electrolytic cell comprising a cathode chamber and an anode chamber, the lower end of the cathode chamber being communicated with one end of a hydrogen ion channel, the other end of the hydrogen ion channel being communicated with the lower end of the anode chamber, a proton exchange membrane for isolating the cathode chamber and the anode chamber being installed in the hydrogen ion channel, and a sealing cover being respectively installed at the top of the cathode chamber and the anode chamber;

[0008] A platinum sheet, the platinum sheet being arranged in the interior of the anode chamber, 0.1M H2SO4 solution being injected into the interior of the anode chamber, and the platinum sheet being completely immersed or partially immersed in the 0.1M H2SO4 solution;

[0009] PtRu electrode, which is arranged inside the cathode chamber, wherein the inside of the cathode chamber 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;

[0010] a power supply, wherein a positive lead of the power supply is connected to one end of the platinum sheet, and a negative lead of the power supply is connected to one end of the PtRu electrode;

[0011] 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.

[0012] As a further scheme of the present application, the platinum sheet is a counter electrode, and the 0.1M H2SO4 solution is an anolyte.

[0013] As a further scheme of the present application, the PtRu electrode is a working electrode, and the 0.1M H2SO4 solution and the 25mM phenol solution constitute a catholyte.

[0014] As a further scheme of the present application, the top of the gas absorption device is connected to a gas injection channel, and the gas injection channel is used to receive nitrogen, hydrogen and volatile products.

[0015] In a second aspect, the present application provides a carbon balance quantification method based on high-value conversion of phenol, which is applied to the carbon balance quantification device based on high-value conversion of phenol as described in the above scheme, and the method comprises the following steps:

[0016] The carbon fiber cloth is thoroughly cleaned, a PtRu electrode is prepared on the cleaned carbon fiber cloth based on a cyclic voltammetry (CV) electrodeposition technology, the prepared PtRu electrode is used as a working electrode, a platinum sheet is used as a counter electrode, and an Ag / AgCl electrode is used as a reference electrode;

[0017] The H-type electrolytic cell is sealed, 0.1M H2SO4 and 25mM phenol are injected into the cathode chamber to form a catholyte, 0.1M H2SO4 is injected into the anode chamber to form an anolyte, a proton exchange membrane is arranged to separate the hydrogen ion channel, a gas absorption device is arranged to be connected to the cathode chamber, and decane is used as a gas absorption solvent in the gas absorption device;

[0018] Nitrogen is introduced into the cathode chamber to start an electrocatalytic hydrogenation (ECH) reaction process of phenol, an electric potential of-0.4V is applied, and after the reaction is continuously performed for 120 minutes, a GC-MS analysis method is used to quantitatively analyze the cyclohexane collected in the gas absorption device.

[0019] As a further scheme of the present application: the GC-MS analysis method is a gas chromatography-mass spectrometry analysis method, the GC-MS analysis method is provided by a gas chromatography-mass spectrometer, and the gas chromatography-mass spectrometry analysis method is an analysis method combining gas chromatography (GC) and mass spectrometry (MS).

[0020] As a further scheme of the present application: the thorough cleaning of the carbon fiber cloth includes:

[0021] The carbon fiber cloth is sequentially cleaned with acetone, ethanol and deionized water (DI water) three times.

[0022] As a further scheme of the present application: the PtRu electrode is prepared on the cleaned carbon fiber cloth based on a cyclic voltammetry (CV) electrodeposition technology, including:

[0023] A 5 mM H2PtCl6·6H2O, 2 mM RuCl3·3H2O and 0.5 M Na2SO4 solution is prepared, and after mixing, it is used as an electrodeposition solution;

[0024] The cyclic scanning period of the cyclic voltammetry is set to 50 times, the potential range is-0.5 V to 1.7 V, and the scanning rate is 100 mV / s, so as to obtain the PtRu electrode;

[0025] The PtRu electrode is cleaned with deionized water and air dried.

[0026] As a further scheme of the present application: the 0.5 M Na2SO4 solution is a supporting electrolyte of the electrodeposition solution.

[0027] As a further scheme of the present application: the PtRu electrode prepared on the cleaned carbon fiber cloth based on the cyclic voltammetry (CV) electrodeposition technology further includes:

[0028] A single-metal Pt / CC is synthesized by using a 5mM Pt metal precursor solution, and a single-metal Ru / CC electrode is synthesized by using a 5mM Ru metal precursor solution.

[0029] As a further scheme of the present application: the proton exchange membrane is a Nafion 117 membrane.

[0030] As a further scheme of the present application: the prepared PtRu electrode is used as a working electrode, including:

[0031] The morphology of the PtRu electrode is observed by using a field emission scanning electron microscope (FESEM, ZEISS Sigma 300) and a high-resolution transmission electron microscope (HR-TEM, Tecnai F20);

[0032] X-ray diffraction (XRD) analysis of the PtRu electrode was performed using an X-ray diffractometer, and X-ray photoelectron spectroscopy analysis of the PtRu electrode was performed using an X-ray photoelectron spectrometer;

[0033] The loadings of Pt and Ru elements in the PtRu electrode were quantitatively analyzed using inductively coupled plasma atomic emission spectrometry (ICP-AES, Thermo Scientific iCAP 7400);

[0034] In-situ Fourier transform infrared spectroscopy (FTIR) of the PtRu electrode was collected using a tellurium cadmium mercury (MCT) detector equipped with liquid nitrogen cooling.

[0035] As a further scheme of the present application: the GC-MS analysis method is used to quantitatively analyze the cyclohexane collected in the gas absorption device, comprising:

[0036] The initial temperature of the chromatographic column is set to 50°C, and maintained for 2 minutes, then heated to 250°C at a rate of 15°C / min, and the temperature of the sample inlet and detector is maintained at 250°C;

[0037] The sample 1 is extracted from the cathode solution using ethyl acetate to extract phenol, cyclohexanone and cyclohexanol, and the sample 2 is cyclohexane absorbed by decane, and the extracted sample is analyzed using gas chromatography (Agilent 8860) with a flame ionization detector (FID) and an HP-5 capillary column (0.25 μm x 0.32 mm x 30 m);

[0038] The carbon balance percentage is calculated.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] 1. The present application captures the volatile product cyclohexane by using a sealed H-type electrolytic cell with a gas adsorption device, and simultaneously evaluates the bimetallic PtRu electrode prepared by the cyclic electrodeposition method, capturing the cyclohexane generated together with cyclohexanone and cyclohexanol, and effectively improving the conversion rate and Faraday efficiency of phenol through the PtRu electrode, which can effectively restore the carbon balance as a whole, promote hydrogenation and subsequent C-O removal, and bridge the gap between selectivity / carbon balance in the long-term phenol electrocatalytic hydrogenation.

[0041] 2. The present application synthesizes a PtRu bimetallic electrode based on the cyclic electrodeposition method, which can accurately quantify the products of the phenol conversion reaction, thereby effectively improving the conversion rate and high Faraday efficiency of phenol, and simultaneously showing excellent selectivity. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1This is a schematic diagram of the electrocatalytic hydrogenation (ECH) of phenol catalyzed by the PtRu catalyst of the present invention;

[0043] 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;

[0044] 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;

[0045] 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;

[0046] 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 5f is the effect of common interfering substances on the performance of phenol ECH.

[0047] Figure 6 a is the calculated d-band center of Pt(111) and PtRu(111); Figure 6 b is the results of phenol on Pt and PtRu showing stronger electron transfer on PtRu; Figure 6 c is the in-situ FTIR spectra of phenol on PtRu electrode at different potentials indicating the stepwise hydrogenation reaction; Figure 6 d is the proposed reaction pathway of phenol ECH;

[0048] Figure 7 is the method steps of the present application.

[0049] In the figure: 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 cover; 10, carbon fiber cloth. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0051] Embodiment:

[0052] As Figure 1As 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.

[0053] 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.

[0054] Preferably, the carbon fiber cloth has an area of ​​2cm × 2cm, and the platinum sheet has an area of ​​2cm × 2cm.

[0055] 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:

[0056] 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.

[0057] 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.

[0058] S3: The ECH reaction of phenol was started by introducing nitrogen into the cathode chamber 5, and the potential was applied at -0.4 V. After 120 minutes of reaction, the collected cyclohexane in the gas absorption device 4 was quantitatively analyzed by GC-MS analysis method.

[0059] In this example, before the preparation of PtRu electrode, the carbon fiber cloth was thoroughly cleaned by sequentially washing with acetone, ethanol and deionized water (DI water) for three times. The PtRu electrode was prepared by cyclic electrodeposition in a three-electrode system, in which a piece of carbon cloth (2 cm x 2 cm) was used as the working electrode, a piece of platinum sheet (2 cm x 2 cm) was used as the counter electrode, and an Ag / AgCl electrode (saturated KCl) was used as the reference electrode. The electrodeposition solution contained 5 mM H2PtCl6·6H2O and 2 mM RuCl3·3H2O, and 0.5 M Na2SO4 was used as the supporting electrolyte. The electrodeposition was carried out by cyclic voltammetry (CV) for 50 cycles 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 of the corresponding metal precursor solution.

[0060] Preferably, the electrode proton exchange membrane is Nafion 117 membrane.

[0061] In this example, during the electrode characterization, the prepared PtRu electrode was used as the working electrode. The morphology of the prepared PtRu electrode was observed by 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 carried out using a Thermo Scientific K-Alpha instrument. The loading of Pt and Ru elements was quantitatively analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES, Thermo Scientific iCAP 7400). In-situ Fourier transform infrared spectroscopy (FTIR) was collected using a Thermo Scientific Nicolet 8700 equipped with a liquid nitrogen-cooled mercury cadmium telluride (MCT) detector.

[0062] In this example, the electrocatalytic hydrogenation (ECH) of phenol was performed in a H-type cell using a three-electrode system, separated by a Nafion 117 membrane. A PtRu electrode (2 cm x 2 cm) was used as the working electrode, a platinum sheet (2 cm x 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 stated, all experiments were repeated three times and the results are reported as the average and standard deviation.

[0063] Ethyl acetate was used to extract phenol and its products, and the extracted samples were analyzed by gas chromatography (Agilent 8860) with a flame ionization detector (FID) and a HP-5 capillary column (0.25 μm x 0.32 mm x 30 m). The temperature of the injection port and detector was maintained at 250 °C. Test sample 1: phenol, cyclohexanone, and cyclohexanol in the catholyte solution were extracted with ethyl acetate; test sample 2: cyclohexane absorbed with decane. The initial temperature of the chromatographic column was 50 °C, maintained for 2 minutes, then increased at a rate of 15 °C / min to 250 °C. The conversion of phenol (%), selectivity (%), yield (%), production rate (mmol cm -2 h -1 ), Faraday efficiency (FE %), and product (cyclohexanone, cyclohexanol, and cyclohexane) and carbon balance (%) were calculated using the following formulas:

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070] where t represents the reaction time (hours), A represents the electrode area (square centimeters), Q is the total amount of charge transferred through the circuit (coulombs), F is the Faraday constant (96485.3 coulombs / mole), and n is the number of electrons involved in the formation of the product (4 for cyclohexanone, 6 for cyclohexanol, and 8 for cyclohexane).

[0071] In this example, electrochemical measurements were performed using a CHI750E electrochemical workstation in a standard three-electrode system, with the prepared PtRu electrode (1 cm x 1 cm) as the working electrode, a platinum sheet (1 cm x 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:

[0072]

[0073] LSV tests were performed in 0.1 M H2SO4 with and without 25 mM phenol, respectively, at a scan rate of 5 mV / s and with 85% iR compensation. CV tests were performed in the non-faradaic region in 0.1 M H2SO4 to calculate the double-layer capacitance (C dl ), which was used to determine the electrochemically 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, in 0.1 M H2SO4 containing 25 mM phenol.

[0074] In this example, the ECH electrode was characterized as follows: The PtRu electrode was prepared on carbon cloth by cyclic electrodeposition in a potential range of -0.5 to 1.7 V vs Ag / AgCl. To achieve the best performance for phenol electrocatalytic hydrogenation (ECH), the loading of Pt and Ru was adjusted by adjusting the molar ratio of the precursors while fixing the concentration of platinum metal salt at 5 mM, and the optimal molar ratio for electrodeposition was determined to be 5:2.

[0075] As shown in Figure 2 a-c, SEM images at different magnifications showed that the deposited metal nanoparticles uniformly covered the carbon cloth fibers, forming an interconnected structure that provided abundant active sites and promoted efficient mass transport.

[0076] As shown in Figure 2 d-e, energy dispersive spectrometer (EDS) mapping further verified the uniform distribution of Pt and Ru elements on the surface. Quantitative EDS analysis showed a Pt:Ru surface atomic ratio of 10.9:1, which was highly consistent with the results obtained by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Transmission electron microscopy (TEM) images of the PtRu deposit showed spherical nanoclusters assembled from smaller nanoparticles, while high-resolution TEM (HR-TEM) identified a lattice spacing of 0.226 nm for Pt(111), as shown in Figure 2 f, and a lattice spacing of 0.222 nm for RuO2(111), which indicated that the Pt 0Pt 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.

[0077] 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.

[0078] 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 Ru 4+ Pt 0 Ru 0 The coexistence of RuO2 indicates the formation of bimetallic interface sites, which is expected to enhance adsorption and electronic interactions.

[0079] 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 3The concentration of cyclohexanol steadily increased to about 15 mM. GC-MS analysis (after ethyl acetate extraction) detected only these two products. However, the total product selectivity for cyclohexanone and cyclohexanol stabilized at about 62%, which is far below the theoretical value of 100%. At the same time, as shown in Figure 3 b, the carbon balance gradually decreased from about 90% at 30 minutes to about 62% at 120 minutes.

[0080] The observed carbon loss was initially hypothesized to be from random error or experimental uncertainty. This prompted us to explore other possible factors - including volatilization, physisorption, membrane crossover, and measurement error - which ultimately proved to be irrelevant. Although this was a step in the wrong direction, it was an important and necessary process of elimination.

[0081] In this example, while troubleshooting the selectivity and carbon balance discrepancies via gas-phase cyclohexane detection, the volatilization of phenol, cyclohexanone, and cyclohexanol was tested by controlling for stirring, but no significant losses were observed. Second, the possibility of organic adsorption to the electrode surface was ruled out by dedicated adsorption tests. Third, the possibility of organic crossover into the anode compartment via the Nafion N117 membrane was ruled out, as no organics were detected in the anode electrolyte. Fourth, the possibility of quantitative error was ruled out by repeatedly recalibrating the GC standard curve. Finally, nitrogen purging experiments confirmed that dissolved oxygen did not affect the electrocatalytic hydrogenation of phenol on PtRu electrodes. Despite these controls, total organic carbon (TOC) measurements consistently decreased after reactions, suggesting that unidentified products could be forming, possibly degrading or converting to volatile organic compounds. This unresolved carbon loss constituted a key obstacle for further analysis and highlighted the urgent need for a more comprehensive product detection strategy.

[0082] As shown in Figure 1 the reactor was sealed, the cathode compartment was connected to a gas absorption device (n-decane trap), and a continuous nitrogen purge was performed. Under these conditions, volatile products were trapped and analyzed. As shown in Figure 3 c, mass spectra showed a mass-to-charge ratio highly consistent with that of a cyclohexane standard, confirming the formation of cyclohexane. After complete conversion of phenol during ECH, cyclohexane accounted for about 32% of the products, with the remainder being cyclohexanone and cyclohexanol; as shown in Figure 3 d, the overall carbon balance was restored to more than 95% when this gaseous fraction was taken into account.

[0083] These results resolved the long-standing discrepancy in selectivity / carbon balance for Pt-based catalysts in acidic media and highlighted a methodological importance: without sealing and gas trapping, volatile products (e.g., cyclohexane) would be systematically underestimated, leading to underestimation of selectivity and faradaic efficiency in the electrocatalytic hydrogenation of phenol.

[0084] In this example, the intrinsic activity of PtRu was preliminarily evaluated by LSV tests with and without 25 mM phenol added in 0.1 M H2SO4 electrolyte, respectively. As shown in Figure 4 a, the onset potential of electrocatalytic hydrogenation of phenol (-0.20 V vs Ag / AgCl) is more negative than that of hydrogen evolution reaction (HER) (-0.25 V vs Ag / AgCl), indicating that the reduction of phenol is more favorable than HER on PtRu electrode. Next, the ECH activity of different electrodes was investigated. At the same potential (-0.40 V vs Ag / AgCl), as shown in Figure 4 b, PtRu electrode shows significantly higher current density of electrocatalytic hydrogenation of phenol than Pt or Ru electrode. As shown in Figure 4 c, this trend is supported by kinetic analysis: 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 PtRu electrode has enhanced reaction kinetics.

[0085] EIS measurements show that PtRu has the lowest charge transfer resistance among the tested samples, consistent with the Tafel results. To evaluate the available surface sites of different electrodes, as shown in Figure 4 d, the electric double layer capacitance (Cdl) was determined by cyclic voltammetry (CV) tests at different scan rates. PtRu electrode shows the highest Cdl value (21.14 mF / cm 2 ), which is greater than that of Pt (18.87 mF / cm 2 ) and Ru (16.90 mF / cm 2 ), indicating that it has a larger electrochemical surface area. These results show that the prepared PtRu electrode has excellent activity and kinetic properties for electrocatalytic hydrogenation of phenol.

[0086] Then, in a sealed H-type cell, as shown in Figure 5 a, a 120-minute benchmark test of real performance was conducted using the optimized potential (-0.40 V vs Ag / AgCl). The pristine carbon cloth has almost no phenol conversion efficiency in 120 minutes. In contrast, the Pt cathode shows a significant improvement in phenol conversion rate (45.7%), but the product Faraday efficiency (FE) is very low (29.4%). This result is mainly attributed to the strong competition of hydrogen evolution reaction (HER), which consumes the surface-adsorbed hydrogen atom (H ads). For the Ru electrode, the phenol 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. Moreover, the PtRu electrode achieved a simultaneous improvement 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 FE of the Pt and Ru electrodes tested separately, confirming the existence of a synergistic enhancement effect of Pt and RuO2 / Ru in the bimetallic electrode. The PtRu electrode showed the highest yield (90.5%) compared to the Pt (38.7%) and Ru (1.31%) electrodes, indicating that the PtRu electrode has excellent catalytic activity.

[0087] In a 60-minute reaction, as shown in Figure 5 b, the dependence of the reaction on the applied potential. As the potential became more negative, the phenol conversion continued to increase; however, the faradaic efficiency (FE) of cyclohexanone steadily decreased. At the same time, the total FE of the products steadily decreased from 70% to 50% due to the competition of the hydrogen evolution reaction (HER) at higher overpotentials. At a cathodic potential of -0.40 V vs Ag / AgCl, as shown in Figure 5 c, a steady accumulation of cyclohexane concentration was observed, reaching approximately 7.9 mM at 120 minutes. As shown in Figure 5 d, the PtRu electrode reached a maximum total FE (66.5%) during the reaction, indicating that it has a high efficiency of electron utilization under optimal conditions. The effect of the initial electrolyte pH on the electrocatalytic hydrogenation (ECH) performance was also studied. The catalytic activity of the PtRu electrode significantly decreased under neutral conditions and was almost completely inhibited in alkaline media. This significant effect indicates that the proton concentration plays a crucial role in driving the phenol hydrogenation process. The durability of PtRu was further evaluated by conducting ten consecutive cycles under the same conditions, as shown in Figure 5 e, no significant loss of activity was observed. The yield remained at 110 µmol / cm 2 / h, highlighting the excellent operational stability of the system. To evaluate its practical applicability, the ECH performance of the PtRu electrode was also tested in the presence of common interfering substances (Cl - , NO3 - , NH4 + , and CH3OH), which are commonly present in industrial phenol wastewater. The results showed that these substances had little effect on the phenol conversion, as shown in Figure 5As shown in Figure f, the PtRu electrode showed excellent selectivity and anti-interference ability. Post-reaction SEM, TEM, XRD and XPS analyses showed that the used PtRu maintained its morphology, crystal structure and surface composition, confirming its strong structural and chemical stability during operation.

[0088] In this example, density functional theory (DFT) calculations were performed to elucidate the catalytic behavior of the PtRu electrode. As shown in Figure Figure 6 a, the d-band center of PtRu (-1.285 eV) was closer to the Fermi level than that of bare Pt (-1.663 eV). Since a less negative d-band center generally enhances the interaction between the metal d-states and the adsorbate, thus enhancing the adsorption and lowering the energy barrier for bond activation. Consistent with this expectation, the adsorption of phenol on PtRu was slightly stronger than on Pt, with adsorption energies of -3.17 eV and -3.10 eV, respectively. Charge density difference analysis showed that the amount of electron transfer from PtRu to the adsorbed phenol (0.46 e - ) was greater than that from Pt to phenol (0.37 e - ), as shown in Figure Figure 6 b, indicating that the metal-adsorbate interaction on PtRu was enhanced, which was beneficial for the first hydrogenation step.

[0089] As shown in Figure Figure 6 c, potential-dependent in-situ Fourier transform infrared (FTIR) spectroscopy was used to track the 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 intensity of the band at 1640 cm -1 (C=O stretching vibration of ketone species, such as cyclohexanone) increased, while the broad O-H stretching band at about 3350 cm -1 (cyclohexanol and phenol) also strengthened. At the same time, the band intensities at 1198 cm -1 (C-O vibration of phenol-OH) and 1495 cm -1 (aromatic C=C) weakened, which was consistent with the hydrogenation of the ring and the conversion of the phenol group.

[0090] To test the importance of liquid products in the formation of cyclohexane, we performed electrolysis experiments on cyclohexanone and cyclohexanol separately (25 mM substrate, 0.1 M H2SO4, -0.40 V vs Ag / AgCl, 120 minutes). As shown in Table 1, cyclohexanone was almost completely converted (99.5%) to cyclohexanol, with a small amount of cyclohexane produced (selectivities of 91.8% and 7.4%, respectively). In contrast, when the ECH reaction of phenol was performed under similar conditions, about 32% of the product was cyclohexane. Cyclohexanol was almost unreactive (0.4% conversion) and no cyclohexane was formed. These results suggest that cyclohexanone and cyclohexanol are not the main precursors of cyclohexane in our aqueous ECH system. In combination with the FTIR spectral results, we also postulate a reaction pathway in which a partially hydrogenated enone intermediate (e.g., cyclohex-3-enone) is formed directly from phenol, followed by a deoxygenation reaction to produce cyclohexane. This postulation is consistent with the following points: (i) theoretical studies have shown that the aqueous hydrogenation of phenol proceeds through cyclohex-3-enone as an intermediate to cyclohexanone; (ii) DFT calculations have shown that the deoxygenation reaction of partially hydrogenated phenol is energetically more favorable than that of cyclohexanol or cyclohexanone.

[0091] 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 ring hydrogenation reaction to form ketone / enone species; subsequently, there are two competing pathways - further hydrogenation to form cyclohexanol, and enone deoxygenation to form cyclohexane. Pt 0 and Ru 0 The coexistence of Pt

[0092] Table 1. ECH reactions of cyclohexanone and cyclohexanol on PtRu electrodes

[0093]

[0094] Reaction conditions: 40 mL of 0.1 M H2SO4 solution, 25 mM cyclohexanone or cyclohexanol added, -0.40 V vs Ag / AgCl, 120 minutes.

[0095] In this example, a hybrid PtRu electrode was successfully synthesized for efficient electrocatalytic hydrogenation (ECH) of aqueous phenol to value-added products (e.g., cyclohexanol and cyclohexane) at ambient conditions. By using a sealed H-cell and combining with a solvent trap for capturing the volatile product cyclohexane, the long-standing carbon balance gap was closed by quantitatively capturing the co-produced cyclohexane along with cyclohexanone and cyclohexanol. Under the optimized conditions, the PtRu electrode exhibited a phenol conversion of 98.9%, a remarkable Faradaic efficiency (FE) of 66.5%, and a selectivity towards cyclohexane of ~32%, restoring the overall carbon balance to >95%. The system demonstrated excellent stability in 10 consecutive cycles and maintained good performance in the presence of common coexisting species, highlighting its practical robustness for phenol wastewater treatment. The PtRu enhanced the adsorption of phenol and the interfacial electron transfer compared to Pt alone, promoting the activation and subsequent hydrogenation of phenol. Overall, a reliable ECH quantitative analysis method was established by combining gas trapping with traditional liquid analysis, (ii) demonstrating a selective and robust PtRu electrode that can efficiently convert phenol to cyclohexanol and cyclohexane. The combined methodological and material progress provides a clear path for accurate product accounting and resource-oriented treatment of phenol wastewater.

[0096] In this example, the reagents include phenol, chloroplatinic acid hexahydrate, rhodium chloride, sodium sulfate, and sulfuric acid. The phenol is C6H6O with a purity of 99.0%, the chloroplatinic acid hexahydrate is H2PtCl6·6H2O with a mass percentage of Pt ≥ 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 received without further purification, and all aqueous solutions use deionized water with a resistivity of more than 18.2 MΩ·cm. -1

[0097] The above merely provides the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, can make equivalent replacements or changes within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.​

Claims

1. A carbon balance quantitative method based on high-value conversion of phenol, applied to a carbon balance quantitative device based on high-value conversion of phenol, characterized in that, The device includes: 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. The platinum sheet is completely or partially immersed in the 0.1M H2SO4 solution. The platinum sheet serves as the counter electrode, and the 0.1M H2SO4 solution serves as the anolyte. 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. A gas cavity is formed between the liquid surface of the mixed solution and the inner top of the cathode chamber. The PtRu electrode is the working electrode, and the catholy solution is composed of 0.1M H2SO4 solution and 25mM phenol solution. 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, the other end of the gas release channel is connected to the gas cavity, and the top of the gas absorption device is connected to a gas injection channel for receiving nitrogen, hydrogen and volatile products; 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.

2. The carbon balance quantitative method based on high-value conversion of phenol according to claim 1, 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.

3. The carbon balance quantitative method based on high-value conversion of phenol according to claim 2, 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.

4. The carbon balance quantitative method based on high-value conversion of phenol according to claim 1, characterized in that: The proton exchange membrane is a Nafion 117 membrane.

5. The carbon balance quantitative method based on high-value conversion of phenol according to claim 1, 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.

6. The carbon balance quantitative method based on high-value conversion of phenol according to claim 5, 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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