Foamed nickel loaded metal basic salt catalytic material and application thereof in electro-catalysis of cyclohexanone oxidation reaction

Abstract

The invention provides a foamed nickel loaded metal basic salt catalytic material and application thereof in electro-catalysis of cyclohexanone oxidation reaction, and belongs to the field of catalytic materials. The metal basic salt catalytic material is characterized in that nickel foam is used as a carrier, and Ni3 (NO3) 2 (OH) 4 or Ni (OH) 1.4 (SO4) 0.3 is loaded on the carrier. The foamed nickel is directly added in the synthesis process, so that the catalyst can directly grow on the foamed nickel to form an integrated self-supporting electrode, and the advantages are that the catalyst is not easy to fall off, and the performance is good. The nickel foam loaded basic nitrate and basic sulfate catalytic materials are applied to cyclohexanone oxidation for the first time, and a good effect is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of catalytic materials, and particularly relates to a metal basic salt catalytic material supported on nickel foam and its application in the electrocatalytic oxidation reaction of cyclohexanone. Background Art

[0002] Adipic acid is a dicarboxylic acid of great industrial significance, and is widely used in the production of important chemical products such as nylon-66 and polybutylene terephthalate, with an annual output of several million tons. At present, the industrial production of adipic acid relies on the oxidation of a cyclohexanone-cyclohexanol mixture, i.e., ketone-alcohol oil (KA oil), with excessive nitric acid as a strong oxidant. This process is mature, but excessive nitric acid will cause equipment corrosion and inevitably produce NO x causing environmental pollution. However, the direct oxidation of benzene or cyclohexene to adipic acid by strong oxidants such as O 3 or H 2 O 2 has the advantages of a short reaction cycle and mild conditions, but the process raw material cost is relatively high.

[0003] In the electrocatalytic oxidation reaction of KA oil to adipic acid (KOR), water is used as the oxidant, and cyclohexanol and cyclohexanone can be highly selectively converted to adipic acid at normal temperature and pressure. The reaction conditions are mild, and high-purity hydrogen gas can be obtained as a by-product at the cathode. If KOR can be industrialized, it can not only reduce the environmental problems caused by NO x but also be further combined with renewable energy power generation to realize the greening of the chemical process, which has important scientific significance and practical application prospects. However, although there have been some high-level research reports in the past three years, the research on electrocatalytic KOR is still in the early stage and still faces challenges such as a complex catalytic reaction mechanism, a relatively limited catalyst design idea, 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 provide a metal basic salt catalytic material supported on nickel foam, a preparation method, and its application in the electrocatalytic oxidation reaction of cyclohexanone.

[0005] The technical solution adopted by this application is as follows:

[0006] A metal basic salt catalytic material, wherein the metal basic salt catalytic material uses nickel foam (nickelfoam, abbreviated as NF) as a carrier, and Ni 3 (NO 3 ) 2 (OH) 4 or Ni(OH) 1.4 (SO 4 ) 0.3 is loaded thereon.

[0007] In some of these embodiments, the metal basic salt catalytic material is Ni supported on nickel foam 3 (NO 3 ) 2 (OH) 4 . When the metal basic salt catalytic material is such, the volume ratio of the nickel foam to the amount of metal Ni ions used is 1 cm 3 :(3.3 - 8.3) mmol;

[0008] and / or; When the metal basic salt catalytic material is Ni(OH) 1.4 (SO 4 ) 0.3 supported on nickel foam, the volume ratio of the nickel foam to the amount of metal Ni ions used is 1 cm 3 :(8.9 - 10) mmol.

[0009] In some of these embodiments, the metal basic salt catalytic material is prepared by a solvothermal method; in the solvothermal method, the nickel foam is not in close contact with the bottom of the reaction vessel and contacts it at a certain angle. During actual operation, the nickel foam is cut so that its area is larger than the bottom area of the reaction vessel, which can make the nickel foam contact the reaction vessel at a certain angle.

[0010] In some of these embodiments, when the metal basic salt catalytic material is Ni 3 (NO 3 ) 2 (OH) 4 supported on nickel foam, the solvothermal method is to disperse the precursor compound of Ni in a solvent, and then add the nickel foam carrier and react to obtain it.

[0011] In some of these embodiments, the precursor compound of Ni is Ni(NO 3 ) 2 ·6H 2 O, the solvent is absolute ethanol, and the ratio of Ni(NO 3 ) 2 ·6H 2 O to absolute 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 of these embodiments, when the metal basic salt catalytic material is Ni(OH) 1.4 (SO 4 ) 0.3When the metal basic salt catalytic material is prepared by the solvent hydrothermal method, the precursor compound of Ni is dispersed in deionized water, ammonia water is added to form a suspension, and then nickel foam carrier and solvent are added, and the reaction is carried out to obtain the product.

[0013] In some of these embodiments, the precursor of Ni is NiSO 4 ·6H 2 O, the solvent is absolute ethanol, and the ratio of NiSO 4 ·6H 2 O to deionized water, ammonia water, and absolute ethanol is 8 - 12 mmol: 15 mL: 3 mL: 15 mL; and / or; the temperature of the reaction is 170 - 190 °C; the reaction time is 22 - 26 h.

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

[0015] a ratio is too low: the metal ion concentration is too high, which easily leads to an overly thick catalytic layer, possibly causing the stacking or aggregation of the lamellar structure, reducing the specific surface area and the exposure of active sites. This results in a decrease in the activity of the inner layer material because the electron and ion transport paths become longer. As a result, the activity of the catalyst may decrease, and the structural stability will also be affected.

[0016] b ratio is too high: the metal ion concentration is too low, resulting in an overly thin catalytic layer loaded on the nickel foam and insufficient active sites. The thin layer may peel off during long-term use, affecting the durability of the catalyst. As a result, the catalyst performance may not be ideal, especially at high current densities.

[0017] Recommended range value

[0018] Based on the general hydrothermal method preparation and catalyst uniformity principle, when the precursor compound of Ni is Ni(NO 3 ) 2 ·6H 2 O, the recommended ratio range of the volume of nickel foam to the molar amount of metal Ni ions is: 1 cm 3 :(3.3 - 8.3) mmol. The ratio used in the examples is 0.9 cm 3 : 3 mmol to 1.2 cm 3 : 10 mmol. When the precursor of Ni is NiSO 4 ·6H 2 O, the recommended ratio range of the volume of nickel foam to the molar amount of metal Ni ions is 1 cm 3 :(8.9 - 10) mmol. The ratio used in the examples is 0.9 cm3 : 8 mmol to 1.2 cm 3 : 12 mmol.

[0019] Reason:

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

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

[0022] A preparation method of a metal basic salt catalytic material, comprising the following steps:

[0023] (1) Pretreat nickel foam;

[0024] (2) Disperse Ni(NO 3 ) 2 ·6H 2 O in 30 mL of absolute ethanol, stir evenly to obtain a solution; the ratio of Ni(NO 3 ) 2 ·6H 2 O to absolute ethanol is 3 - 10 mmol: 30 mL;

[0025] (3) Add the pretreated nickel foam into the above solution, and transfer it to a hydrothermal reaction kettle, react at 110 - 130 °C for 22 - 26 h; the volume ratio of the nickel foam to the amount of Ni ions used is 1 cm 3 : (3.3 - 8.3) mmol; the nickel foam is not in close contact with the bottom of the hydrothermal reaction kettle and is in contact at a certain angle;

[0026] (4) Rinse the reacted nickel foam with deionized water and absolute ethanol respectively, and dry it in vacuum at 50 - 70 °C for 3 - 12 h to prepare a metal basic salt catalytic material of nickel foam supported Ni 3 (NO 3 ) 2 (OH) 4 .

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

[0028] A preparation method of a metal basic salt catalytic material, comprising the following steps:

[0029] S1 Pretreat nickel foam;

[0030] S2 disperses 8 - 12 mmol of NiSO 4 ·6H 2 O in 15 mL of deionized water and stirs evenly;

[0031] S3 slowly drops 3 mL of ammonia water into the above - mentioned solution and stirs evenly with magnetic force to obtain a suspension;

[0032] S4 adds the pretreated nickel foam into the above - mentioned suspension, then adds 15 mL of absolute ethanol, and transfers it to a hydrothermal reaction kettle, and reacts at 170 - 190 °C for 22 - 26 h; the volume ratio of the nickel foam to the dosage of Ni ions is 1 cm 3 :(8.9 - 10) mmol; the nickel foam is not in close contact with the bottom of the hydrothermal reaction kettle and contacts at a certain angle;

[0033] S5 rinses the reacted nickel foam with deionized water and absolute ethanol respectively, and dries it in vacuum at 50 - 70 °C for 3 - 12 h to prepare a metal basic salt catalytic material of nickel foam - supported Ni(OH) 1.4 (SO 4 ) 0.3 2.

[0034] In some of these embodiments, step S1 pre - treats the nickel foam, including: ultrasonically treating the nickel foam in absolute ethanol, 3M HCl, deionized water, and absolute ethanol for 8 - 15 min respectively.

[0035] Application of the metal basic salt catalytic material described in any one of the above in the electro - catalytic oxidation reaction of cyclohexanone.

[0036] The beneficial effects of this application are:

[0037] This application first applies the nickel - foam - supported basic nitrate and basic sulfate catalytic materials to the oxidation of cyclohexanone and obtains good results.

[0038] Adding nickel foam directly during the synthesis process can enable the catalyst to grow directly on the nickel foam, forming an integrated self - supported electrode. The advantage of this is that the catalyst is not easy to fall off, has good performance, and is superior to the powdered catalyst.

[0039] The basic nitrate and basic sulfate catalytic materials prepared by this application through Example 2 and Example 3 have excellent electro - catalytic activity for the oxidation of cyclohexanone to adipic acid. The current densities at a potential of 1.527 V (vs. RHE) can reach 73.4 mA / cm 2 2, 27.4 mA / cm 2 2 respectively, which are superior to Ni(OH) 2 / NF (26.9 mA / cm 2) and, compared with the oxygen evolution reaction, the current density difference is also greater than that of Ni(OH) 2 / NF.

[0040] In this application, basic salt catalytic materials containing different acid root anions are prepared by a solvothermal method. The presence of the oxyacid root anion in the structure not only improves the activity of the electrocatalytic oxidation of cyclohexanone to adipic acid, but also increases the selectivity of adipic acid in the liquid phase products. Through the regulation of the oxyacid root anion, the adsorption of basic nitrate and basic sulfate materials on cyclohexanone is enhanced, and the conversion of cyclohexanone to the key intermediate hydroxycyclohexanone is promoted, improving the electrocatalytic activity and selectivity of the materials. Description of the Drawings

[0041] Figure 1 is the SEM image of the Ni(OH) 2 / NF catalytic material.

[0042] Figure 2 is the SEM image of the NiNH / NF catalytic material.

[0043] Figure 3 is the SEM image of the NiSH / NF catalytic material.

[0044] Figure 4 is the XRD pattern of Example 1 (Ni(OH) 2 / NF), Example 2 (NiNH / NF), and Example 3 (NiSH / NF).

[0045] Figure 5 is the XPS spectrum of the catalytic materials prepared in each example to determine the states of the elements in the catalyst.

[0046] Figure 6 are the polarization curves of the electrocatalytic oxidation of cyclohexanone and oxygen evolution of the catalytic materials prepared in each example, as well as the corresponding current density differences between the two.

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

[0048] In the following examples of the present invention, the experimental methods without specific conditions are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. All kinds of commonly used chemical reagents used in the examples are commercially available products.

[0049] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0050] The term "comprising" and "having" and any variations thereof in the present invention 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 listed steps or modules, but may optionally further include steps not listed, or may optionally further include other steps inherent to these processes, methods, products or devices.

[0051] In the present invention, the mention of "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0052] In this application, Ni 3 (NO 3 ) 2 (OH) 4 / NF is abbreviated as (NiNH) / NF; Ni(OH) 1.4 (SO 4 ) 0.3 / NF is abbreviated as (NiSH) / NF.

[0053] In this application, by designing basic nitrate catalytic materials and basic sulfate catalytic materials, an oxygen-containing acid root anion regulation strategy is used to improve the activity of the electrocatalytic oxidation of cyclohexanone to synthesize adipic acid.

[0054] Since metal basic salts (M(OH) x (A) y , A = F - , CO 3 2- , NO 3 - , SO 4 2- etc.) are structurally similar to hydroxides and contain additional acid root anions. The acid root ions contained in metal basic salts will affect the formation of the true active species MOOH (transition metal hydroxyoxides), thus promising to further improve the KOR activity of the materials. Aiming at the deficiencies of the prior art, this application provides a preparation method for basic nitrate and basic sulfate catalytic materials. This preparation method mainly prepares various basic salt catalysts supported on nickel foam by a solvothermal method. Metal basic salts containing acid root anions have excellent reaction activity in the electrocatalytic oxidation of cyclohexanone.

[0055] The nickel foam mentioned above is a sound-absorbing material with excellent performance and has a relatively high sound absorption coefficient at high frequencies. The sound absorption performance at low frequencies can be improved through the design of the sound absorption structure. In the application field of catalyst materials, the unique open-cell structure, low-pressure input holes, inherent tensile strength, and thermal shock resistance of nickel foam make it possible to become the catalyst carrier for automotive catalyst 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 in the examples is a conventional ammonia water product, that is, an aqueous solution containing 25% - 28% ammonia.

[0057] This application provides a preparation method for different basic salt catalysts, which specifically includes the following steps:

[0058] Pretreatment of the substrate nickel foam (NF)

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

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

[0061] Cut into 2×4 cm 2 The function is to ensure that it is placed in the 50 mL reaction kettle at a certain angle and does not lie flat at the bottom of the reaction kettle.

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

[0063] 2. Ultrasonically treat the nickel foam in absolute ethanol, 3M HCl, deionized water, and absolute ethanol for 10 min in sequence;

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

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

[0066] Use the treated nickel foam to prepare the following catalytic materials.

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

[0068] A. Weigh 5 mmol Ni(NO 3 ) 2 ·6H 2 O (1.4540 g) and disperse it in 30 mL of deionized water, and magnetically stir to obtain a uniform solution A;

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

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

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

[0072] E. Rinse the sample synthesized in step D with deionized water and absolute ethanol respectively, and dry it in vacuum at 60 °C overnight to obtain the Ni(OH) 2 catalytic material supported on nickel foam.

[0073] Example 2: Preparation of Ni 3 (NO 3 ) 2 (OH) 4 / NF Catalytic Material

[0074] A. Weigh 5 mmol of Ni(NO 3 ) 2 ·6H 2 O (1.4540 g) and disperse it in 30 mL of absolute ethanol. Stir magnetically to obtain a homogeneous solution A;

[0075] B. Add the pretreated nickel foam (2×4×0.15 cm 3 ) to solution A and transfer it to a 50 mL hydrothermal reactor. React at 120 °C for 24 h;

[0076] C. Rinse the sample synthesized in step B with deionized water and absolute ethanol respectively, and dry it in vacuum at 60 °C overnight to obtain the NiNH / NF catalytic material supported on nickel foam.

[0077] Since the precursor of Ni in this synthesis method is only Ni(NO 3 ) 2 ·6H 2 O, a certain structure of nickel basic nitrate can be obtained, that is, Ni 3 (NO 3 ) 2 (OH) 4 . Using other precursor compounds of Ni, Ni(NO 3 ) 2 ·6H 2 O cannot be prepared. However, due to Ni(NO 3 ) 2 ·6H in the solution2 The amount of O precursor is different, which will affect the normal growth of the catalyst on the surface of nickel foam and further lead to different catalytic activities. Only within the preferred range of this application can a NiNH / NF catalyst with normal growth, uniform texture, and a nanosheet array structure be obtained on the surface of nickel foam.

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

[0079] Example 3: Ni(OH) 1.4 (SO 4 ) 0.3 Preparation of / NF Catalytic Material

[0080] A. Weigh 10 mmol NiSO 4 ·6H 2 O (2.6285 g) and disperse it in 15 mL of deionized water, and magnetically stir to obtain a uniform solution A;

[0081] B. Slowly drop 3 mL of ammonia water (NH 3 ·H 2 O) into solution A, and magnetically stir to obtain a uniform suspension B;

[0082] C. Add the pretreated nickel foam into suspension B, transfer it to a 50 mL hydrothermal reaction kettle, and then add 15 mL of anhydrous ethanol, and react at 180 °C for 24 h;

[0083] E. Rinse the sample synthesized in step C with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 60 °C overnight to obtain a nickel foam-supported NiSH catalytic material.

[0084] The difference between Example 1 and Example 2 is that the catalytic material structure does not contain the acid radical anion NO 3 - .

[0085] The difference between Example 1 and Example 3 is that the catalytic material structure does not contain the acid radical anion SO 4 2- .

[0086] Perform performance tests on the catalytic materials prepared in the three examples.

[0087] Figure 1 、 2 、3 are the SEM images of Ni(OH) 2 / NF, NiNH / NF, and NiSH / NF catalytic materials respectively.

[0088] As can be seen from the figure: After synthesis by the solvothermal method, Ni(OH) 2 , NiNH, and NiSH all grew well on the nickel foam substrate. Among them, the morphology of NiNH is an array formed by densely packed nanosheets, and the thickness of the nanosheets is relatively thin and the size is relatively small. Ni(OH) 2 also has a similar nanosheet array structure, and the thickness and size of its nanosheets are relatively large. NiSH has a relatively uniform nanobelt morphology.

[0089] According to the statistical analysis of the SEM results, the thickness of the NiNH nanosheets is about 20 nm, and the size is about 200 - 300 nm. Ni(OH) 2 The thickness of the nanosheets is about 200 - 300 nm, and the size ranges from several hundred nanometers to 1 μm. The width of the NiSH nanobelts is about 100 nm, and the length is several tens of micrometers.

[0090] Figure 4 are the XRD spectra of the catalytic materials of each example.

[0091] As Figure 4 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 respectively match well with the standard PDF cards PDF#14 - 0117, PDF#22 - 0752, and PDF#41 - 1424 of Ni(OH) 2 , Ni 3 (NO 3 ) 2 (OH) 4 and Ni(OH) 1.4 (SO 4 ) 0.3 , and no additional impurity peaks appear, indicating that Ni(OH) 2 / NF, Ni 3 (NO 3 ) 2 (OH) 4 / NF, and Ni(OH) 1.4 (SO 4 ) 0.3 / NF catalysts were successfully prepared by the solvothermal reaction.

[0092] Figure 5 are the XPS spectra of the samples prepared in each example to determine the states of the elements in the catalyst.

[0093] As Figure 5 a shows, from Ni(OH) 2 , Ni 3 (NO 3 )2 (OH) 4 and Ni(OH) 1.4 (SO 4 ) 0.3 In the Ni 2p spectra of, two obvious main peaks can be seen at ~856.3 eV and ~873.3 eV, and two satellite peaks are observed at ~861.8 eV and ~880.1 eV. The positions of the two main peaks and the satellite peaks are consistent with those of Ni with unpaired 3d electrons reported in the literature 2+ of Ni 2p 3 / 2 and Ni2p 1 / 2 signals. In the O1s spectrum ( Figure 5 b), the main peak at 531.2 eV corresponds to the O-H bond in metal hydroxides (531 - 532 eV), and the peak at 532.7 eV should be attributed to the oxygen bond in H 2 O. Ni 3 (NO 3 ) 2 (OH) 4 The single peak at 406.8 eV in the N1s spectrum of belongs to NO 3 - ( Figure 5 c); The single S2p peak at ~168.6 eV in Ni(OH) 1.4 (SO 4 ) 0.3 is consistent with the position of SO in sulfate compounds 4 2- ( Figure 5 d). According to the XPS analysis results of the surface element valence states of the three catalytic material samples, it can be found that the valence state of nickel ions in the three catalysts is all +2. It has been confirmed by previous studies that in the anodic oxidation reaction, divalent nickel ions are not the real active substances, and they will be converted into higher-valent nickel ions 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 reaction of cyclohexanone.

[0096] Specific operation method: Using an electrochemical workstation (Shanghai Chenhua CHI604E) under 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 tests were carried out in an H-type electrolytic cell separated by an anion exchange membrane. All potentials in the tests were calibrated relative to the reversible hydrogen electrode potential (RHE). In the experiment, 1.0 M KOH and 1.0 M KOH + 0.1 M cyclohexanone were used as electrolytes.

[0097] Briefly speaking, for the electrocatalytic oxidation reaction, the catalyst (such as hydroxides and basic salts of transition metals, etc.) will generate corresponding hydroxyoxides (MOOH) under the action of the applied potential as the active substance to catalyze the oxidation of cyclohexanone to produce the target product adipic acid. For metal basic salts and Ni(OH) without anions 2 catalysts, their reaction paths for catalyzing the oxidation of cyclohexanone to adipic acid are the same. In addition, since this reaction is relatively complex, there is no particularly clear reaction mechanism at present. Based on the results reported in the literature as a reference, the inventors believe that using the catalyst prepared in this application to catalyze this reaction will not change the existing reaction mechanism.

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

[0099] The electrochemical performance of the prepared catalyst was evaluated using an H-type electrolytic cell separated by an anion exchange membrane under alkaline conditions. First, under the condition of 1.0 M KOH, a CV test was carried out using a typical three-electrode system at a scan rate of 100 mV s -1 to fully activate the prepared catalyst. Subsequently, under the condition of 1.0 M KOH + 0.1 M cyclohexanone, an LSV test was carried out with a scan rate of 5 mV s -1 . The results are shown in Figure 6 , the polarization curves of electrocatalytic oxidation of cyclohexanone and oxygen evolution and the corresponding current density differences of the catalytic material samples prepared in each example. Specifically, the abscissa of the LSV curve is the tested potential (vs. RHE), and the ordinate is the current density. According to the measured LSV curve, the current density under a certain potential condition can be further read.

[0100] From Figure 6 the results in a, it can be seen that in the case where cyclohexanone is not contained in the electrolyte, Ni(OH) 2 / NF, Ni(OH) 1.4 (SO 4 ) 0.3 / NF and Ni 3 (NO 3 ) 2 (OH) 4 / NF have obvious oxygen evolution (OER) catalytic activity, and the performance of Ni 3 (NO 3 ) 2 (OH) 4 / NF is significantly better than that of Ni(OH) 2 / NF and Ni(OH) 1.4 (SO 4 ) 0.3 / NF. However, when 0.1 M cyclohexanone is added to the electrolyte, it can be observed that, whether it is the Ni(OH) 2 / NF, Ni(OH) 1.4 (SO 4 ) 0.3 / NF or Ni 3 (NO 3 ) 2 (OH) 4 / NF catalyst, all show a significantly enhanced current density response, indicating that cyclohexanone is more easily oxidized than water, thus endowing the above catalysts with obvious electrocatalytic cyclohexanone oxidation activity. In addition, the current density response of the Ni 3 (NO 3 ) 2 (OH) 4 / NF catalyst is also significantly higher than that of the Ni(OH) 2 / NF and Ni(OH) 1.4 (SO 4 ) 0.3 / NF catalysts, indicating that the Ni 3 (NO 3 ) 2 (OH) 4 / NF catalyst has higher catalytic reaction activity. Figure 6 b is the calculated current density difference of Ni(OH) 2 / NF, Ni(OH) 1.4 (SO 4 ) 0.3 / NF and Ni 3 (NO 3 ) 2 (OH) 4 / NF under different potential conditions for catalyzing OER and cyclohexanone oxidation. As can be seen from Figure 6 b, Ni 3 (NO 3 ) 2 (OH) 4 / NF and Ni(OH) 1.4 (SO 4 ) 0.3 / NF have a significantly larger current density difference than Ni(OH) 2 / NF, indicating that during the catalysis of cyclohexanone oxidation, it has better reaction activity. That is, in cyclohexanone, due to the presence of NO 3 - and SO 4 2- in the structure, it is beneficial to promote the catalytic reaction activity, that is, there is an anion effect.

[0101] The present invention prepares basic nitrate and basic sulfate catalysts containing different acid radical anions supported on nickel foam by a solvothermal method for the electrocatalytic oxidation of cyclohexanone, and the successful preparation is proved by XRD spectra and XPS tests. Among them, NiNH / NF prepared in Example 2 has excellent electrocatalytic cyclohexanone oxidation performance. It can be observed from the polarization curve of Figure 6 that the current density reaches 73.4 mA / cm 2 at a potential of 1.527 V (vs. RHE), which is better than that of Ni(OH) 2 / NF (26.9 mA / cm 2 ) in Example 1.

[0102] Comparative Example 1

[0103] For the preparation of the NiSH / NF catalyst: When using less amounts of NiSO 4 ·6H 2 O (such as 1 mmol, 0.26285 g) and 3 mL of ammonia water, other steps are the same as in Example 3.

[0104] Result: Due to the small amount of NiSO 4 ·6H 2 O used, it is difficult for NiSH / NF to grow on nickel foam, and it is impossible to obtain the NiSH / NF catalyst supported on nickel foam.

[0105] When using more NiSO 4 ·6H 2 O (such as 20 mmol, 5.2570 g) and 3 mL of ammonia water, other steps are the same as in Example 3. Possibly due to the lower proportion of ammonia water, the NiSH / NF supported on nickel foam cannot be synthesized either.

[0106] The NiSH / NF catalyst has strict requirements for the amount of Ni precursor compounds growing on nickel foam. The inventors found in their research that 1 mmol, 3 mmol, and 5 mmol of the Ni precursor NiSO 4 ·6H 2 O, corresponding to the scheme of 3 mL of ammonia water, cannot in-situ grow NiSH on nickel foam.

[0107] The results are shown in Figure 7 .

[0108] Figure 7 In, (a) is the cleaned nickel foam (before the reaction), (b) is the nickel foam after the reaction with a small amount (3 mmol) of NiSO 4 ·6H 2 O, and (c) is the moderate (10 mmol) NiSO 4 ·6H 2The nickel foam after the reaction.

[0109] As can be seen from Figure 7 , the nickel foam before the hydrothermal reaction has an obvious metallic luster. After reacting with a small amount of NiSO 4 ·6H 2 O, the surface of the nickel foam becomes darker, and almost no catalytic material grows on its surface. After reacting with a moderate amount of NiSO 4 ·6H 2 O, a light green NiSH catalytic material obviously grows on the surface of the nickel foam.

[0110] Comparative Example 2

[0111] When the size of the nickel foam is cut into an area of 2×2×0.15 cm 3 , other steps are the same as those in Example 3.

[0112] Since the diameter of the 50 mL reaction kettle is about 2.5 - 3 cm, the nickel foam will directly lie flat on the bottom of the reaction kettle. This results in less or no catalyst growing on the side of the nickel foam facing the bottom of the reaction kettle, thereby affecting the catalytic activity.

[0113] Traditional Ni-Fe and Ni-Co catalysts are usually disordered nanoparticles or nanoaggregates, which adhere to the surface of the nickel foam. Their nanoparticle structures are prone to agglomeration problems, and the distribution of active sites is uneven, resulting in a relatively low specific surface area and limited catalytic efficiency. In contrast, the basic nitrate catalyst of the present application is prepared by a hydrothermal method, forming a regular nanosheet or nanolayer structure, which uniformly covers the three-dimensional porous substrate of the nickel foam. The sheet structure is beneficial to increasing the surface area and providing more active sites. Moreover, nickel foam is introduced during the synthesis process, and NiNH / NiSH is directly grown in situ on the nickel foam as a self-supporting electrode for subsequent performance testing.

[0114] For the powder catalysts in the prior art, a glassy carbon electrode is required during subsequent use, or they are coated on supports such as carriers for performance testing. However, in the synthesis process of the present application, nickel foam is directly added, enabling the catalyst to directly grow on the nickel foam, forming an integrated self-supporting electrode. The advantage of this is that the catalyst is not easily detached, and the performance is usually better than the results obtained by directly testing the powder catalyst samples.

[0115] Industrial Application Example

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

[0117] Adipic acid is a dicarboxylic acid of great industrial significance and is widely used in the production of important chemical products such as nylon-66 and polybutylene terephthalate. Existing industrial production technologies of adipic acid will produce NO x which pollutes the environment, causes equipment corrosion, and the high cost of process raw materials also greatly limits its development. In addition, existing catalysts are still limited to oxide, hydroxide, and oxyhydroxide materials, and the reaction activity of these materials for electrocatalytic oxidation of cyclohexanone to adipic acid is relatively low.

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

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

[0120]

[0121]

[0122] The results in Table 1 show that the basic nitrate and basic sulfate catalytic materials prepared in this invention through Example 2 and Example 3 have excellent reaction activity for electrocatalytic oxidation of cyclohexanone to adipic acid, and the current densities at a potential of 1.527 V (vs. RHE) can reach 73.4 mA / cm 2 and 27.4 mA / cm 2 , which are better than Ni(OH) 2 / NF (26.9 mA / cm 2 ) in Example 1, and when compared with the current density during the oxygen evolution reaction, the difference in the current densities of the two reactions for cyclohexanone oxidation by NiNH / NF and NiSH / NF is also greater than that of Ni(OH) 2 / NF.

[0123] This application prepared basic salt catalytic materials supported on nickel foam containing different acid root anions through a solvothermal method. The presence of the oxoacid root anion in the structure not only improves the activity of the electrocatalytic oxidation of cyclohexanone to synthesize adipic acid, but also increases the selectivity of adipic acid in the liquid phase product. Through the regulation of the oxoacid root anion, the adsorption of basic nitrate and basic sulfate materials on cyclohexanone is enhanced, and the conversion of cyclohexanone to the key intermediate hydroxycyclohexanone is promoted, improving the electrocatalytic activity and selectivity of the materials.

[0124] Currently, the catalysts used for the cyclohexanone oxidation reaction include nickel oxyhydroxide (NiOOH), Ni(OH) 2 doped with Cu and V, Co 3 O 4 / graphdiyne composite catalyst, and CuCo 2 O4 , NiOOH / Ni(OH) 2 Materials, etc. For the first time in this application, the catalytic materials of basic nitrate (NiNH / NF) and basic sulfate (NiSH / NF) supported on nickel foam are applied to the oxidation of cyclohexanone, and good results are obtained.

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

Claims

1. A metal basic salt catalytic material, characterized in that: The metal basic salt catalytic material is based on nickel foam as a carrier, on which Ni3(NO3)2(OH)4 or Ni(OH) is loaded. 1.4 (SO4) 0.3 Metal basic salt catalytic materials.

2. The metal basic salt catalytic material according to claim 1, characterized in that: When the metal basic salt catalytic material is a metal basic salt catalytic material in which Ni3(NO3)2(OH)4 is loaded on nickel foam, the ratio of the volume of the nickel foam to the amount of the metal Ni ion is 1 cm 3 :(3.3-8.3)mmol; And / or; the metal basic salt catalytic material is Ni(OH) loaded on nickel foam 1.4 (SO4) 0.3 When the metal basic salt catalyst material is used, the ratio of the volume of the nickel foam to the metal Ni ion is 1 cm 3 :(8.9-10)mmol.

3. The metal basic salt catalytic material according to claim 2, characterized in that: The metal basic salt catalytic material is prepared by a solvent thermal method; in the solvent thermal method, the nickel foam is not in a close contact state with the bottom of the reaction container.

4. The metal basic salt catalytic material according to any one of claims 1 to 3, characterized in that: When the metal basic salt catalytic material is a metal basic salt catalytic material in which Ni3(NO3)2(OH)4 is loaded on nickel foam, the solvent hydrothermal method is to disperse the Ni precursor compound in a solvent, then add the nickel foam carrier, and react to obtain the result.

5. The metal basic salt catalytic material according to claim 4, characterized in that: The Ni precursor compound is Ni(NO3)2·6H2O, the solvent is anhydrous ethanol, the ratio of Ni(NO3)2·6H2O to anhydrous ethanol is 3-10mmol:30mL; and / or; the reaction temperature is 110-130°C, and the reaction time is 22-26h.

6. The metal basic salt catalytic material according to any one of claims 1 to 3, characterized in that: The metal basic salt catalytic material is Ni(OH) loaded on nickel foam 1.4 (SO4) 0.3 When the metal basic salt catalytic material is used, the solvent hydrothermal method is to disperse the Ni precursor compound in deionized water, add ammonia water to form a suspension, and then add the foamed nickel carrier and the solvent to react to obtain.

7. The metal basic salt catalytic material according to claim 6, characterized in that: The Ni precursor is NiSO4·6H2O, the solvent is anhydrous ethanol, the ratio of NiSO4·6H2O to deionized water, ammonia water, and anhydrous ethanol is 8-12mmol:15mL:3mL:15mL; and / or; the reaction temperature is 170-190°C; and the reaction time is 22-26h.

8. A method for preparing a metal basic salt catalytic material, characterized in that: The following steps are involved: (1) pre-treating nickel foam; (2) dispersing Ni(NO3)2·6H2O in 30 mL of anhydrous ethanol and stirring 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 for reaction at 110-130° C. for 22-26 h; the volume ratio of the nickel foam to the amount of Ni ions is 1 cm 3 :(3.3-8.3)mmol; the nickel foam is not in close contact with the bottom of the hydrothermal reactor; (4) The nickel foam after the reaction is rinsed with deionized water and anhydrous ethanol respectively, and vacuum dried at 50-70° C. for 3-12 h to prepare a metal basic salt catalytic material of Ni3(NO3)2(OH)4 supported on nickel foam.

9. A method for preparing a metal basic salt catalytic material, characterized in that: The following steps are involved: S1 pre-treats the nickel foam; S2 Disperse 8-12mmol NiSO4·6H2O in 15mL deionized water and stir evenly; S3 Slowly drip 3 mL of ammonia water into the above solution and stir evenly with magnetic force to obtain a suspension; S4: Add the pretreated nickel foam to the above suspension, add 15 mL of anhydrous ethanol, and transfer to a hydrothermal reactor for reaction at 170-190 °C for 22-26 h; the volume ratio of the nickel foam to the Ni ion is 1 cm 3 :(8.9-10)mmol; the nickel foam is not in close contact with the bottom of the hydrothermal reactor; S5: The nickel foam after the reaction is rinsed with deionized water and anhydrous ethanol respectively, and dried in a vacuum oven at 50-70°C for 3-12h to prepare nickel foam loaded Ni(OH) 1.4 (SO4) 0.3 Metal basic salt catalytic materials.

10. Use of the metal basic salt catalytic material according to any one of claims 1 to 7 in the electrocatalytic oxidation reaction of cyclohexanone.

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