Foam nickel supported metal basic salt catalytic material and its application in electrocatalytic oxidation of cyclohexanone

Abstract

This invention provides a nickel foam-supported metal basic salt catalyst and its application in the electrocatalytic oxidation of cyclohexanone, belonging to the field of catalytic materials. The metal basic salt catalyst uses nickel foam as a support, on which Ni3(NO3)2(OH)4 or Ni(OH)4 is loaded. 1.4 (SO4) 0.3 This application describes a metal basic salt catalyst. By directly adding nickel foam during the synthesis process, the catalyst can grow directly on the nickel foam, forming an integrated self-supporting electrode. This has the advantage of preventing catalyst detachment and ensuring good performance. This application is the first to apply nickel foam-supported basic nitrate and basic sulfate catalysts to the oxidation of cyclohexanone, achieving excellent results.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials, specifically relating to nickel foam-supported metal basic salt catalytic materials and their application in the electrocatalytic oxidation of cyclohexanone. Background Technology

[0002] Adipic acid is an industrially important dicarboxylic acid, widely used in the production of important chemical products such as nylon-66 and polybutylene terephthalate, with an annual output of millions of tons. Currently, the industrial production of adipic acid relies on the oxidation of cyclohexanone-cyclohexanol mixtures, i.e., ketone-alcohol oil (KA oil), by using excess nitric acid as a strong oxidant. This process is mature, but excess nitric acid can cause equipment corrosion and inevitably produce NO. x This causes environmental pollution. Benzene or cyclohexene can be directly oxidized to adipic acid by strong oxidants such as O3 or H2O2. This process has the advantages of a short reaction cycle and mild conditions, but the cost of raw materials is relatively high.

[0003] The kinase-oxidation (KOR) reaction, using water as the oxidant, can selectively convert cyclohexanol and cyclohexanone into adipic acid at room temperature and pressure. The reaction conditions are mild, and high-purity hydrogen is produced as a byproduct at the cathode. If KOR can be industrialized, it can not only reduce NO₂ levels... x It addresses the environmental problems caused by chemical processes and can be further integrated with renewable energy power generation to achieve greening of chemical processes, which has significant scientific importance and practical application prospects. However, although some high-level research has been reported in the past three years, the research on electrocatalytic KOR is still in its early stages and faces challenges such as complex catalytic reaction mechanisms, relatively limited catalyst design ideas, and low catalytic activity. Summary of the Invention

[0004] The purpose of this application is to overcome at least one deficiency of the prior art and to provide a nickel foam-supported metal basic salt catalytic material, a preparation method thereof, and its application in the electrocatalytic oxidation of cyclohexanone.

[0005] The technical solution adopted in this application is:

[0006] A basic metal salt catalytic material, wherein the basic metal salt catalytic material uses nickel foam (NF) as a support, on which Ni3(NO3)2(OH)4 or Ni(OH) is loaded. 1.4 (SO4) 0.3 Metal basic salt catalytic materials.

[0007] In some embodiments, when the basic metal salt catalyst is a basic metal salt catalyst with Ni3(NO3)2(OH)4 supported on nickel foam, the volume ratio of the nickel foam to the amount of Ni ions is 1 cm³.3 (3.3-8.3) mmol;

[0008] And / or; the basic metal salt catalyst is Ni(OH) supported on nickel foam. 1.4 (SO4) 0.3 When using basic metal salt catalysts, the volume ratio of the nickel foam to the amount of Ni ions is 1 cm³. 3 :(8.9-10)mmol.

[0009] In some embodiments, the basic metal salt catalyst is prepared by a solvothermal method; in this solvothermal method, the nickel foam is not in close contact with the bottom of the reaction vessel, but rather at an angle. In actual operation, the nickel foam is cut so that its area is larger than the bottom area of ​​the reaction vessel, thus allowing the nickel foam to contact the reaction vessel at an angle.

[0010] In some embodiments, when the metal basic salt catalyst is a metal basic salt catalyst with Ni3(NO3)2(OH)4 supported on nickel foam, the solvothermal method involves dispersing the precursor compound of Ni in a solvent, adding the nickel foam support, and reacting to obtain the catalyst.

[0011] In some embodiments, the precursor compound of Ni is Ni(NO3)2·6H2O, the solvent is anhydrous ethanol, and the ratio of Ni(NO3)2·6H2O to anhydrous ethanol is 3-10 mmol:30 mL; and / or; the reaction temperature is 110-130 °C, and the reaction time is 22-26 h.

[0012] In some embodiments, the basic metal salt catalyst is Ni(OH) supported on nickel foam. 1.4 (SO4) 0.3 When preparing a basic metal salt catalytic material, the solvothermal method involves dispersing the Ni precursor compound in deionized water, adding ammonia to form a suspension, then adding a nickel foam support and solvent, and reacting to obtain the final product.

[0013] In some embodiments, the precursor of Ni is NiSO4·6H2O, the solvent is anhydrous ethanol, and the ratio of NiSO4·6H2O to deionized water, ammonia, and anhydrous ethanol is 8-12 mmol:15 mL:3 mL:15 mL; and / or; the reaction temperature is 170-190°C; and the reaction time is 22-26 h.

[0014] The ratio of the volume of the nickel foam substrate to the total molar amount of transition metal source ions affects the structure and performance of the final catalyst. This ratio determines the concentration of metal ions on the nickel foam surface, thus influencing the thickness, uniformity, and final catalytic performance of the catalyst layer.

[0015] A low a / b ratio indicates an excessively high metal ion concentration, which can lead to an overly thick catalyst layer. This may cause the accumulation or agglomeration of lamellar structures, reducing the specific surface area and the exposure of active sites. This results in decreased activity of the inner layer material due to longer electron and ion transport paths. Consequently, the catalyst's activity may decrease, and its structural stability may also be affected.

[0016] An excessively high beta ratio indicates a low metal ion concentration, resulting in an excessively thin catalyst layer supported on nickel foam and an insufficient number of active sites. This thin layer may peel off during long-term use, affecting catalyst durability. Consequently, catalyst performance may be less than ideal, especially at high current densities.

[0017] Recommended range values

[0018] Based on the general hydrothermal preparation method and the principle of catalyst uniformity, when the precursor compound of Ni is Ni(NO3)2·6H2O, the recommended range for the ratio of nickel foam volume to the molar amount of metallic Ni ions is: 1 cm³ 3 (3.3-8.3) mmol. The ratio used in the examples was 0.9 cm. 3 3mmol to 1.2cm 3 10 mmol. When the Ni precursor is NiSO4·6H2O, the recommended volume-to-molar ratio of nickel foam to metallic Ni ions is within the range of 1 cm³. 3 (8.9-10) mmol. The ratio used in the examples is 0.9 cm. 3 8mmol to 1.2cm 3 12 mmol.

[0019] reason:

[0020] Lower limit: Ensure that the metal ion concentration is high enough to form a uniform and continuous catalyst layer, while avoiding excessively thick accumulation.

[0021] Upper limit: Ensure that the metal ion concentration is not too low, so as to uniformly cover the surface of the nickel foam, while avoiding the catalyst instability caused by the layer being too thin.

[0022] A method for preparing a basic metal salt catalytic material includes the following steps:

[0023] (1) Pretreatment of nickel foam;

[0024] (2) Disperse Ni(NO3)2·6H2O in 30mL of anhydrous ethanol and stir until homogeneous to obtain a solution; the ratio of Ni(NO3)2·6H2O to anhydrous ethanol is 3-10mmol:30mL.

[0025] (3) Add the pretreated nickel foam to the above solution and transfer it to a hydrothermal reactor. React at 110-130℃ for 22-26 hours; the volume ratio of the nickel foam to the amount of Ni ions is 1 cm³. 3 (3.3-8.3) mmol; The nickel foam is not in close contact with the bottom of the hydrothermal reactor, but at a certain angle;

[0026] (4) The reacted nickel foam was rinsed with deionized water and anhydrous ethanol, and then dried under vacuum at 50-70℃ for 3-12h to prepare the basic metal salt catalyst material of nickel foam supported on Ni3(NO3)2(OH)4.

[0027] In some embodiments, step (1) pretreatment of nickel foam includes: ultrasonic treatment of nickel foam in anhydrous ethanol, 3M HCl, deionized water and anhydrous ethanol for 8-15 minutes respectively.

[0028] A method for preparing a basic metal salt catalytic material includes the following steps:

[0029] S1 is used for pretreatment of nickel foam;

[0030] S2 Disperse 8-12 mmol NiSO4·6H2O in 15 mL of deionized water and stir until homogeneous;

[0031] S3 slowly added 3 mL of ammonia water to the above solution and stirred magnetically until homogeneous to obtain a suspension;

[0032] S4. Add the pretreated nickel foam to the above suspension, then add 15 mL of anhydrous ethanol, and transfer to a hydrothermal reactor. React at 170-190℃ for 22-26 h; the volume ratio of the nickel foam to the amount of Ni ions is 1 cm³. 3 (8.9-10) mmol; The nickel foam is not in close contact with the bottom of the hydrothermal reactor, but at a certain angle;

[0033] S5 The reacted nickel foam was washed with deionized water and anhydrous ethanol, respectively, and then vacuum dried at 50-70℃ for 3-12 hours to prepare nickel foam-supported Ni(OH). 1.4 (SO4) 0.3 Metal basic salt catalytic materials.

[0034] In some embodiments, step S1 pretreatment of the nickel foam includes: ultrasonic treatment of the nickel foam in anhydrous ethanol, 3M HCl, deionized water and anhydrous ethanol for 8-15 minutes respectively.

[0035] The application of any of the metal basic salt catalysts described above in the electrocatalytic oxidation of cyclohexanone.

[0036] The beneficial effects of this application are:

[0037] This application is the first to apply basic nitrate and basic sulfate catalysts supported on nickel foam to the oxidation of cyclohexanone, and good results have been obtained.

[0038] In this application, the addition of nickel foam during the synthesis process allows the catalyst to grow directly on the nickel foam, forming an integrated self-supporting electrode. The advantage of this is that the catalyst is not easily detached, has good performance, and is superior to powdered catalysts.

[0039] The basic nitrate and basic sulfate catalytic materials prepared in Examples 2 and 3 of this application exhibit excellent electrocatalytic activity for the oxidation of cyclohexanone to adipic acid, achieving current densities of 73.4 mA / cm² at a potential of 1.527 V (vs. RHE). 2 27.4 mA / cm 2 The Ni(OH)2 / NF ratio is superior to that of Example 1 (26.9 mA / cm²). 2 Furthermore, the current density difference is greater than that of Ni(OH)2 / NF compared to the oxygen evolution reaction.

[0040] This application describes the preparation of basic salt catalytic materials containing different acid radical anions via a solvothermal method. The presence of oxyanion anions in the structure not only enhances the electrocatalytic activity of the oxidation of cyclohexanone to adipic acid but also improves the selectivity of adipic acid in the liquid-phase product. By regulating the oxyanion content, the adsorption of cyclohexanone by basic nitrate and basic sulfate materials is enhanced, and the conversion of cyclohexanone to the key intermediate hydroxycyclohexanone is promoted, thereby improving the electrocatalytic activity and selectivity of the materials. Attached Figure Description

[0041] Figure 1 This is a SEM image of the Ni(OH)2 / NF catalyst.

[0042] Figure 2 This is a SEM image of the NiNH / NF catalyst.

[0043] Figure 3 This is a SEM image of the NiSH / NF catalyst.

[0044] Figure 4 The XRD patterns are for Example 1 (Ni(OH)2 / NF), Example 2 (NiNH / NF), and Example 3 (NiSH / NF).

[0045] Figure 5 XPS spectra of the catalytic materials prepared in each embodiment are used to determine the state of each element in the catalyst.

[0046] Figure 6The polarization curves of electrocatalytic cyclohexanone oxidation and oxygen evolution of the catalyst materials prepared in each embodiment, as well as the corresponding current density difference between the two.

[0047] Figure 7 The morphology of nickel foam before and after the reaction. Detailed Implementation

[0048] Unless otherwise specified, the experimental methods described in the following embodiments of the present invention are generally performed under conventional conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the embodiments are commercially available products.

[0049] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0050] The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps is not limited to the steps or modules listed, but may optionally include steps not listed, or may optionally include other steps inherent to such process, method, product, or device.

[0051] In this invention, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0052] In this application, Ni3(NO3)2(OH)4 / NF is abbreviated as (NiNH) / NF; Ni(OH) 1.4 (SO4) 0.3 / NF is abbreviated as (NiSH) / NF.

[0053] This application improves the activity of the electrocatalytic oxidation of cyclohexanone to adipic acid by designing basic nitrate and basic sulfate catalysts and using an oxyanion-controlled strategy.

[0054] Due to the basic metal salt (M(OH)) x (A) y A = F - CO3 2- NO3 - SO4 2-These basic metal salts are structurally similar to hydroxides and contain additional acid radical anions. The acid radical ions in these basic metal salts can influence the formation of the true active species MOOH (transition metal hydroxyl oxide), potentially further improving the KOR activity of the material. To address the shortcomings of existing technologies, this application provides a method for preparing basic nitrate and basic sulfate catalytic materials. This method primarily involves a solvothermal process to prepare various basic salt catalysts supported on nickel foam. The basic metal salts containing acid radical anions exhibit excellent reactivity in the electrocatalytic oxidation of cyclohexanone.

[0055] Nickel foam is a high-performance sound-absorbing material with a high sound absorption coefficient at high frequencies; its low-frequency sound absorption performance can be improved through sound-absorbing structure design. In the field of catalyst materials, nickel foam's unique open-cell structure, low-pressure injection holes, inherent tensile strength, and thermal shock resistance make it a potential catalyst carrier for automotive catalytic converters, catalytic combustion, and diesel vehicle black smoke purifiers. The nickel foam used in the examples is a commercially available product.

[0056] The ammonia water used in the examples is a conventional ammonia water product, i.e., an aqueous solution containing 25% to 28% ammonia.

[0057] This application provides methods for preparing different basic salt catalysts, specifically including the following steps:

[0058] Pretreatment of substrate nickel foam (NF)

[0059] 1. First, cut the nickel foam into pieces measuring 2×4×0.15cm. 3 ;

[0060] Nickel foam is a commercially available catalyst carrier, and there are no special requirements for the selection of this raw material; commercially available products can be chosen.

[0061] Cut into 2×4cm 2 Its function is to ensure that it is placed at a certain angle in the 50mL reactor, so that it does not lie flat on the bottom of the reactor.

[0062] Those skilled in the art can also adjust the size of the nickel foam used according to the size of the reactor.

[0063] 2. The nickel foam was ultrasonically treated in anhydrous ethanol, 3M HCl, deionized water, and anhydrous ethanol for 10 min in sequence.

[0064] 3. Vacuum dry using a vacuum drying oven.

[0065] The purpose of vacuum drying is to prevent the foamed nickel, whose oxide layer has been washed off, from being further oxidized in the air.

[0066] The following catalytic materials were prepared using treated nickel foam.

[0067] Example 1: Preparation of Ni(OH)2 / NF catalytic material

[0068] A. Weigh 5 mmol of Ni(NO3)2·6H2O (1.4540 g) and disperse it in 30 mL of deionized water. Stir magnetically to obtain a homogeneous solution A.

[0069] B. Weigh 0.16g NaOH (0.004mol) and disperse it in 40mL of deionized water. Sonicate the solution for 5min to form a homogeneous solution B.

[0070] C. Add solution B dropwise to solution A, and then stir continuously to adjust the pH to about 6.5 to obtain solution C;

[0071] D. Place the pretreated nickel foam (2×4×0.15cm) 3 Add the solution to solution C and transfer it to a 50 mL hydrothermal reactor. React at 120 °C for 6 h.

[0072] E. The sample synthesized in step D was rinsed with deionized water and anhydrous ethanol, and then dried under vacuum at 60°C overnight to obtain Ni(OH)2 catalyst material supported on nickel foam.

[0073] Example 2: Preparation of Ni3(NO3)2(OH)4 / NF catalytic material

[0074] A. Weigh 5 mmol of Ni(NO3)2·6H2O (1.4540 g) and disperse it in 30 mL of anhydrous ethanol. Stir magnetically to obtain a homogeneous solution A.

[0075] B. Place the pre-treated nickel foam (2×4×0.15cm) 3 Add the contents to solution A and transfer them to a 50 mL hydrothermal reactor. React at 120 °C for 24 h.

[0076] C. The sample synthesized in step B was rinsed with deionized water and anhydrous ethanol, and dried under vacuum at 60°C overnight to obtain the nickel foam-supported NiNH / NF catalyst.

[0077] Because the only Ni precursor in this synthesis method is Ni(NO3)2·6H2O, a basic nickel nitrate with a specific structure, Ni3(NO3)2(OH)4, can be obtained. However, using other Ni precursor compounds cannot produce Ni(NO3)2·6H2O. Furthermore, the amount of Ni(NO3)2·6H2O precursor in the solution affects the normal growth of the catalyst on the nickel foam surface, further leading to variations in catalytic activity. Only within the preferred scope of this application can a NiNH / NF catalyst with normal growth on the nickel foam surface, uniform texture, and a nanosheet array structure be obtained.

[0078] The preferred solvent is anhydrous ethanol, which is a homogeneous solution and has little impact on the hydrothermal method. This will ensure the growth of the catalyst on the nickel foam as much as possible, thus obtaining a uniform catalyst.

[0079] Example 3: Ni(OH) 1.4 (SO4) 0.3 Preparation of / NF catalytic materials

[0080] A. Weigh 10 mmol NiSO4·6H2O (2.6285 g) and disperse it in 15 mL of deionized water. Stir magnetically to obtain a homogeneous solution A.

[0081] B. Slowly add 3 mL of ammonia water (NH3·H2O) dropwise to solution A and stir magnetically to obtain a uniform suspension B;

[0082] C. Add the pretreated nickel foam to suspension B and transfer it to a 50mL hydrothermal reactor. Then add 15mL of anhydrous ethanol and react at 180℃ for 24h.

[0083] E. The sample synthesized in step C was rinsed with deionized water and anhydrous ethanol, and then vacuum dried at 60°C overnight to obtain the NiSH catalyst material supported on nickel foam.

[0084] The difference between Example 1 and Example 2 is that the catalytic material structure does not contain the acid radical anion NO3. - .

[0085] The difference between Example 1 and Example 3 is that the catalytic material structure does not contain the acid radical anion SO4. 2- .

[0086] The performance of the catalytic materials prepared in the three examples was tested.

[0087] Figure 1 , 2 Figures 1, 2, and 3 are SEM images of Ni(OH)2 / NF, NiNH / NF, and NiSH / NF catalysts, respectively.

[0088] As shown in the figure, after synthesis using the solvothermal method, Ni(OH)₂, NiNH, and NiSH all grew well on the nickel foam substrate. Among them, NiNH has a morphology of densely packed nanosheet arrays, and the nanosheets are relatively thin and small in size. Ni(OH)₂ also has a similar nanosheet array structure, but its nanosheets are relatively thick and large in size. NiSH has a more uniform nanoribbon morphology.

[0089] Statistical analysis of SEM results shows that NiNH nanosheets are approximately 20 nm thick and 200–300 nm in size. Ni(OH)₂ nanosheets are approximately 200–300 nm thick and range in size from hundreds of nanometers to 1 μm. NiSH nanoribbons are approximately 100 nm wide and tens of micrometers long.

[0090] Figure 4 The images show the XRD patterns of the catalyst materials in each embodiment.

[0091] like Figure 4 As shown, the strong diffraction peaks at 2θ angles of 44.5°, 51.9°, and 76.4° are consistent with the diffraction peaks of the conductive substrate NF (PDF#87-0712), while the other peaks are consistent with Ni(OH)2, Ni3(NO3)2(OH)4, and Ni(OH), respectively. 1.4 (SO4) 0.3 The standard PDF cards PDF#14-0117, PDF#22-0752, and PDF#41-1424 showed a perfect match, and no additional impurity peaks appeared, indicating that Ni(OH)2 / NF, Ni3(NO3)2(OH)4 / NF, and Ni(OH)2 were successfully prepared via solvothermal reaction. 1.4 (SO4) 0.3 / NF catalyst.

[0092] Figure 5 XPS spectra of samples prepared for each embodiment were used to determine the state of elements in the catalyst.

[0093] like Figure 5 As shown in Figure a, from Ni(OH)2, Ni3(NO3)2(OH)4 and Ni(OH) 1.4 (SO4) 0.3 The Ni 2p spectrum shows two distinct main peaks at ~856.3 eV and ~873.3 eV, and two satellite peaks at ~861.8 eV and ~880.1 eV. The positions of the main peaks and satellite peaks are consistent with those reported in the literature for Ni with unpaired 3d electrons. 2+ Ni 2p 3 / 2 and Ni2p 1 / 2 The signals are consistent. However, in the O1s spectrum ( Figure 5(b) The main peak at 531.2 eV corresponds to the OH bond in the metal hydroxide (531–532 eV), while the peak at 532.7 eV should be attributed to the oxygen bond in H₂O. The single peak at 406.8 eV in the N1s spectrum of Ni₃(NO₃)₂(OH)₄ belongs to NO₃⁻. - ( Figure 5 c); Ni(OH) 1.4 (SO4) 0.3 A single S2p peak at ~168.6 eV corresponds to SO4 in sulfate compounds. 2- Consistent positions Figure 5 d). Based on XPS analysis of the surface elemental valence states of the three catalytic material samples, it was found that the nickel ions in all three catalysts were in the +2 valence state. Previous studies have confirmed that in the anodic oxidation reaction, the +2 nickel ion is not the truly active substance; it will transform into a higher valence state nickel ion to promote the kinetics of the cyclohexanone oxidation reaction.

[0094] Application Example 1

[0095] The nickel foam-supported catalytic materials prepared in Examples 1-3 were used in the electrocatalytic oxidation of cyclohexanone.

[0096] Specific operating procedures: An electrochemical workstation (Shanghai Chenhua CHI604E) was used in a three-electrode system with Hg / HgO as the reference electrode, a carbon rod as the counter electrode, and the prepared catalyst as the working electrode. Electrochemical performance was tested in an H-type electrolytic cell separated by anion exchange membranes. All potentials were calibrated relative to the reversible hydrogen electrode potential (RHE). 1.0 M KOH and 1.0 M KOH + 0.1 M cyclohexanone were used as electrolytes in the experiment.

[0097] In simple terms, for electrocatalytic oxidation reactions, the catalyst (such as transition metal hydroxides, basic salts, etc.) generates corresponding hydroxyl oxides (MOOH) under the influence of an applied potential, which act as active substances to catalyze the oxidation of cyclohexanone to the target product, adipic acid. The reaction pathway for the oxidation of cyclohexanone to adipic acid is the same for both metal basic salts and Ni(OH)₂ catalysts that do not contain anions. Furthermore, due to the complexity of this reaction, a particularly well-defined reaction mechanism is currently lacking. Based on the results reported in the literature, the inventors believe that using the catalyst prepared in this application to catalyze this reaction will not alter the existing reaction mechanism.

[0098] The method for polarization curve testing is as follows:

[0099] The electrochemical performance of the prepared catalyst was evaluated under alkaline conditions using an H-type electrolytic cell separated by anion exchange membranes. First, under 1.0 M KOH conditions, a typical three-electrode system was used at 100 mV s⁻¹. -1 The scan rate was used to perform CV testing to ensure sufficient activation of the prepared catalyst. Subsequently, LSV testing was performed under 1.0 M KOH + 0.1 M cyclohexanone conditions at a scan rate of 5 mV / s. -1 The results are shown below. Figure 6 The polarization curves of electrocatalytic cyclohexanone oxidation and oxygen evolution of the catalytic material samples prepared in each embodiment, as well as the corresponding current density difference between the two, are shown. Specifically, the horizontal axis of the LSV curve represents the test potential (vs. RHE), and the vertical axis represents the current density. The current density under a certain potential condition can be further read based on the measured LSV curve.

[0100] from Figure 6 The results in a show that, in the absence of cyclohexanone in the electrolyte, Ni(OH)2 / NF and Ni(OH)2 / NF are... 1.4 (SO4) 0.3 Both / NF and Ni3(NO3)2(OH)4 / NF exhibit significant oxygen evolution reaction (OER) catalytic activity, with Ni3(NO3)2(OH)4 / NF showing significantly better performance than Ni(OH)2 / NF and Ni(OH)2 / NF. 1.4 (SO4) 0.3 / NF. However, when 0.1M cyclohexanone was added to the electrolyte, it was observed that regardless of Ni(OH)2 / NF or Ni(OH)2 / NF... 1.4 (SO4) 0.3 Both the Ni3(NO3)2(OH)4 / NF and Ni3(NO3)2(OH)4 / NF catalysts exhibited significantly enhanced current density responses, indicating that cyclohexanone is more readily oxidized than water, thus giving these catalysts significant electrocatalytic activity for cyclohexanone oxidation. Furthermore, the current density response of the Ni3(NO3)2(OH)4 / NF catalyst was also significantly higher than that of Ni(OH)2 / NF and Ni(OH)2 / NF. 1.4 (SO4) 0.3 The presence of the Ni3(NO3)2(OH)4 / NF catalyst indicates that the Ni3(NO3)2(OH)4 / NF catalyst has higher catalytic activity. Figure 6 b represents the calculated Ni(OH)₂ / NF and Ni(OH)₂. 1.4 (SO4) 0.3 The difference in current density between / NF and Ni3(NO3)2(OH)4 / NF under different potential conditions during the catalytic oxidation of OER and cyclohexanone. Figure 6 b indicates that Ni3(NO3)2(OH)4 / NF and Ni(OH) 1.4 (SO4) 0.3The current density difference between / NF and Ni(OH)2 / NF is significantly greater than that between / NF and Ni(OH)2 / NF, indicating that / NF has better reactivity in catalyzing the oxidation of cyclohexanone. This is because, in cyclohexanone, the presence of NO3 in the structure... - and SO4 2- The presence of ions promotes catalytic reaction activity, which means that there is an anion effect.

[0101] This invention prepared basic nitrate and basic sulfate catalysts containing different acid radicals supported on nickel foam via a solvothermal method for the electrocatalytic oxidation of cyclohexanone. The successful preparation was confirmed by XRD and XPS measurements. Specifically, the NiNH / NF catalyst prepared in Example 2 exhibited excellent electrocatalytic cyclohexanone oxidation performance. Figure 6 The polarization curves show a current density of 73.4 mA / cm² at a potential of 1.527 V (vs. RHE). 2 The Ni(OH)2 / NF ratio is superior to that of Example 1 (26.9 mA / cm²). 2 ).

[0102] Comparative Example 1

[0103] For the preparation of the NiSH / NF catalyst: when using a smaller amount of NiSO4·6H2O (e.g., 1 mmol, 0.26285 g) and 3 mL of ammonia, the other steps are the same as in Example 3.

[0104] Results: Due to the small amount of NiSO4·6H2O, it is difficult for NiSH / NF to grow on nickel foam, and it is impossible to obtain a NiSH / NF catalyst supported on nickel foam.

[0105] When using more NiSO4·6H2O (e.g., 20 mmol, 5.2570 g) and 3 mL of ammonia, the other steps were the same as in Example 3. Possibly due to the lower proportion of ammonia, the resulting nickel-supported NiSH / NF foam could not be synthesized.

[0106] The NiSH / NF catalyst has strict requirements on the amount of Ni precursor compound used for growth on nickel foam. The inventors found that the methods of using 1 mmol, 3 mmol, and 5 mmol of Ni precursor NiSO4·6H2O, corresponding to 3 mL of ammonia water, could not grow NiSH in situ on nickel foam.

[0107] See results Figure 7 .

[0108] Figure 7 In the figures, (a) is cleaned nickel foam (before reaction), (b) is nickel foam after reaction with a small amount (3 mmol) of NiSO4·6H2O, and (c) is nickel foam after reaction with a moderate amount (10 mmol) of NiSO4·6H2O preferred in this application.

[0109] from Figure 7 As can be seen, the nickel foam before the hydrothermal reaction has a distinct metallic luster. However, after reacting with a small amount of NiSO4·6H2O, the surface of the nickel foam darkens, and almost no catalytic material grows on its surface. But after reacting with a moderate amount of NiSO4·6H2O, a light green NiSH catalytic material is clearly grown on the surface of the nickel foam.

[0110] Comparative Example 2

[0111] When the nickel foam is cut to a size of 2×2×0.15cm 3 The area is determined, and the other steps are the same as in Example 3.

[0112] Since the diameter of a 50mL reactor is approximately 2.5–3cm, the nickel foam will spread directly and evenly at the bottom of the reactor. This results in less or no catalyst growing on the side of the nickel foam facing the bottom of the reactor, thus affecting catalytic activity.

[0113] Traditional Ni-Fe and Ni-Co catalysts are typically disordered nanoparticles or nanoagglomerates attached to the surface of nickel foam. Their nanoparticle structures are prone to agglomeration, resulting in uneven distribution of active sites, low specific surface area, and limited catalytic efficiency. In contrast, the basic nitrate catalyst of this application is prepared via a hydrothermal method, forming regular nanosheets or nanolayers that uniformly cover the three-dimensional porous substrate of nickel foam. The sheet-like structure helps increase the surface area and provide more active sites. Furthermore, the introduction of nickel foam during synthesis allows NiNH / NiSH to be directly grown in situ on the nickel foam as a self-supporting electrode for subsequent performance testing.

[0114] For existing powdered catalysts, a glassy carbon electrode is required for subsequent use, or they need to be coated onto a support or other substrate for performance testing. However, this application directly incorporates nickel foam during the synthesis process, allowing the catalyst to grow directly on the nickel foam and form an integrated self-supporting electrode. The advantage of this is that the catalyst is less likely to detach, and the performance is generally better than that obtained by directly testing powdered catalyst samples.

[0115] Industrial Application Examples

[0116] This invention provides the application of basic nitrate (NiNH / NF) and basic sulfate (NiSH / NF) catalytic materials in the electrocatalytic oxidation of cyclohexanone.

[0117] Adipic acid is an industrially important dicarboxylic acid, widely used in the production of important chemical products such as nylon-66 and polybutylene terephthalate. Current industrial production technologies for adipic acid generate NO. xThe process pollutes the environment, causes equipment corrosion, and the high cost of raw materials severely limits its development. Furthermore, existing catalysts are still limited to oxides, hydroxides, and hydroxyl oxides, and these materials exhibit low reactivity in the electrocatalytic oxidation of cyclohexanone to adipic acid.

[0118] The catalytic material prepared in this application was used in the electrocatalytic oxidation of cyclohexanone, and the specific test data are shown in Table 1.

[0119] Table 1. Comparison of electrochemical performance of various catalysts for cyclohexanone oxidation and water oxidation.

[0120]

[0121]

[0122] Table 1 shows that the basic nitrate and basic sulfate catalytic materials prepared in Examples 2 and 3 of this invention exhibit excellent electrocatalytic activity for the oxidation of cyclohexanone to adipic acid, with current densities reaching 73.4 mA / cm² at a potential of 1.527 V (vs. RHE). 2 27.4 mA / cm 2 The Ni(OH)2 / NF ratio is superior to that of Example 1 (26.9 mA / cm²). 2 Furthermore, compared to the current density during the oxygen evolution reaction, the difference in current density between the two reactions during the oxidation of cyclohexanone catalyzed by NiNH / NF and NiSH / NF is also greater than the difference in current density between Ni(OH)2 / NF.

[0123] This application describes the preparation of basic salt catalytic materials containing different acid radical anions supported on nickel foam via a solvothermal method. The presence of oxyanion anions in the structure not only enhances the electrocatalytic activity of the oxidation of cyclohexanone to adipic acid but also improves the selectivity of adipic acid in the liquid-phase product. By regulating the oxyanion content, the adsorption of cyclohexanone by basic nitrate and basic sulfate materials is enhanced, and the conversion of cyclohexanone to the key intermediate hydroxycyclohexanone is promoted, thereby improving the electrocatalytic activity and selectivity of the materials.

[0124] Currently, catalysts used for the oxidation of cyclohexanone include nickel hydroxide (NiOOH), Cu / V doped Ni(OH)₂, Co₃O₄ / graphyne composite catalysts, and CuCo₂O₄, NiOOH / Ni(OH)₂ materials. This application is the first to apply nickel foam-supported basic nitrate (NiNH / NF) and basic sulfate (NiSH / NF) catalysts to the oxidation of cyclohexanone, achieving excellent results.

[0125] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. The application of basic metal salt catalysts in the electrocatalytic oxidation of cyclohexanone, characterized in that, The metal basic salt catalyst material uses nickel foam as a support, on which Ni3(NO3)2(OH)4 or Ni(OH) is loaded. 1.4 (SO4) 0.3 The metal basic salt catalytic material is prepared by a solvothermal method; the nickel foam is not in close contact with the bottom of the reaction vessel during the solvothermal method; when the metal basic salt catalytic material is a Ni3(NO3)2(OH)4 supported on nickel foam, the volume ratio of the nickel foam to the amount of Ni ions is 1 cm³. 3 (3.3-8.3) mmol; when the basic metal salt catalyst is Ni(OH) supported on nickel foam. 1.4 (SO4) 0.3 When using a basic metal salt catalytic material, the volume ratio of the nickel foam to the amount of Ni ions is 1 cm³. 3 : (8.9-10) mmol.

2. The application according to claim 1, characterized in that, When the metal basic salt catalytic material is a metal basic salt catalytic material with Ni3(NO3)2(OH)4 supported on nickel foam, the solvothermal method involves dispersing the Ni precursor compound in a solvent by stirring, then adding the nickel foam support, and reacting to obtain the catalyst. The Ni precursor compound is Ni(NO3)2·6H2O, the solvent is anhydrous ethanol, and the ratio of Ni(NO3)2·6H2O to anhydrous ethanol is 3~10 mmol : 30 mL. The reaction temperature is 110-130℃, and the reaction time is 22-26 h.

3. The application according to claim 1, characterized in that, The basic metal salt catalyst is Ni(OH) supported on nickel foam. 1.4 (SO4) 0.3 When preparing a basic metal salt catalytic material, the solvothermal method involves dispersing the Ni precursor compound in deionized water by stirring, adding ammonia to form a suspension, then adding a nickel foam support and solvent, and reacting to obtain the product. The Ni precursor is NiSO4·6H2O, the solvent is anhydrous ethanol, and the ratio of NiSO4·6H2O to deionized water, ammonia, and anhydrous ethanol is 8-12 mmol:15 mL:3 mL:15 mL. The reaction temperature is 170-190℃, and the reaction time is 22-26 h.

4. The application according to claim 2, characterized in that, The preparation method of the metal basic salt catalytic material includes the following steps: (1) Pretreatment of nickel foam; (2) Disperse Ni(NO3)2·6H2O in 30 mL of anhydrous ethanol and stir until homogeneous to obtain a solution; the ratio of Ni(NO3)2·6H2O to anhydrous ethanol is 3~10 mmol : 30 mL; (3) Add the pretreated nickel foam to the above solution and transfer it to a hydrothermal reactor. React at 110-130℃ for 22-26 h; the volume ratio of the nickel foam to the amount of Ni ions is 1 cm³. 3 (3.3-8.3) mmol; the nickel foam is not in close contact with the bottom of the hydrothermal reactor; (4) The reacted nickel foam was rinsed with deionized water and anhydrous ethanol, and then dried under vacuum at 50-70℃ for 3-12h to prepare the basic metal salt catalyst material of nickel foam supported on Ni3(NO3)2(OH)4.

5. The application according to claim 3, characterized in that, The preparation method of the metal basic salt catalytic material includes the following steps: S1 is used for pretreatment of nickel foam; S2 Disperse 8-12 mmol NiSO4·6H2O in 15 mL of deionized water and stir until homogeneous; S3 slowly added 3 mL of ammonia water to the above solution and stirred magnetically until homogeneous to obtain a suspension; S4. The pretreated nickel foam is added to the above suspension, followed by 15 mL of anhydrous ethanol. The mixture is then transferred to a hydrothermal reactor and reacted at 170-190°C for 22-26 hours. The volume ratio of the nickel foam to the amount of Ni ions is 1 cm³. 3 (8.9-10) mmol; the nickel foam is not in close contact with the bottom of the hydrothermal reactor; S5 The reacted nickel foam was washed with deionized water and anhydrous ethanol, respectively, and then vacuum dried at 50-70℃ for 3-12 hours to prepare nickel foam-supported Ni(OH). 1.4 (SO4) 0.3 Metal basic salt catalytic materials.

6. The application according to any one of claims 1-5, characterized in that, The metal basic salt catalytic material is used as an integrated self-supporting catalytic electrode in the electrocatalytic oxidation of cyclohexanone.

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