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CN-121976228-A - Mesoporous palladium-silver alloy electrocatalyst for efficiently synthesizing cyclohexanone oxime, and preparation method and application thereof

CN121976228ACN 121976228 ACN121976228 ACN 121976228ACN-121976228-A

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a mesoporous palladium-silver alloy electrocatalyst for efficiently synthesizing cyclohexanone oxime, a preparation method and application thereof, which are characterized in that: the catalyst is prepared by dissolving dioctadecyl dimethyl ammonium chloride in a mixed solution of deionized water and ethanol, sequentially adding a sodium hydroxide solution, a metal precursor palladium chloride acid, a silver nitrate solution and the like, and then washing and drying. The catalyst is prepared by adopting a one-step soft template co-reduction method, the obtained catalyst has high electron conductivity, so that high-efficiency charge transmission is ensured, no carrier is designed, the falling of active components or carrier corrosion instability are avoided, the electrochemical dissolution resistance is enhanced by palladium-silver alloy phase components, and the technical problems of low Faraday efficiency, low yield and the like of the conventional electrocatalyst are overcome.

Inventors

  • SUN LIZHI
  • LIU BEN
  • Jing Yuqian

Assignees

  • 四川大学

Dates

Publication Date
20260505
Application Date
20260204
Priority Date
20260122

Claims (10)

  1. 1. A mesoporous palladium-silver alloy electrocatalyst for efficiently synthesizing cyclohexanone oxime is characterized in that the catalyst is of a palladium-silver alloy integral spherical structure with three-dimensional communicated nano pore channels, the diameter of the catalyst is 34-36 nm, pd in components is Ag=65.5-66.2:32.6-33.2, and the pore diameter distribution is in a range of 2-5 nm.
  2. 2. A mesoporous palladium-silver alloy electrocatalyst for efficient synthesis of cyclohexanone oxime according to claim 1, wherein the diameter is 35 nm, pd: ag=66:34.
  3. 3. The preparation method of the mesoporous palladium-silver alloy electrocatalyst for efficiently synthesizing cyclohexanone oxime is characterized by comprising the following steps of: (1) Dissolving dioctadecyl dimethyl ammonium chloride in a mixed solution of deionized water and ethanol; (2) Adding sodium hydroxide solution, and standing for reacting for 4-6 min; (3) Adding a metal precursor chloropalladate and silver nitrate solution, and performing self-assembly on the solution 28-32 min to obtain a solution containing a metal precursor-template composite micelle; (4) Adding ascorbic acid solution to perform reduction reaction for 1.8-2.2h; (5) And after the reduction is finished, centrifugally washing and drying the mixture by using absolute ethyl alcohol and deionized water to obtain the mesoporous palladium-silver alloy.
  4. 4. The preparation method of the mesoporous palladium-silver alloy electrocatalyst for efficiently synthesizing cyclohexanone oxime according to claim 3, wherein in the step (1), at 68-72 ℃, dioctadecyl dimethyl ammonium chloride is dissolved in deionized water, and cooled to room temperature to obtain a uniform template solution, and in an optimized scheme, the temperature in the step (1) is 70 ℃.
  5. 5. The method for preparing the mesoporous palladium-silver alloy electrocatalyst for efficiently synthesizing cyclohexanone oxime according to claim 3, wherein the dosage is calculated by mass volume, and dioctadecyl dimethyl ammonium chloride, deionized water, chloropalladite solution, and silver nitrate solution are respectively added, wherein the ratio of ascorbic acid solution=2.8-3.2:9-11:0.18-0.22:0.46-0.5:0.22-0.25:1.
  6. 6. The preparation method of the mesoporous palladium-silver alloy electrocatalyst for efficiently synthesizing cyclohexanone oxime according to claim 5, wherein dioctadecyl dimethyl ammonium chloride, deionized water, chloropalladite solution, and ascorbic acid solution = 3:10:0.2:0.48:0.24:1.
  7. 7. A process for preparing mesoporous palladium-silver alloy electrocatalyst for high-efficiency synthesis of cyclohexanone oxime according to claim 3, wherein the molar concentration of NaOH solution is 0.1 mol/L.
  8. 8. A process for preparing mesoporous palladium-silver alloy electrocatalyst for high-efficiency synthesis of cyclohexanone oxime according to claim 3, wherein the molar concentrations of the chloropalladite solution and the silver nitrate solution are respectively 10 mmol/L.
  9. 9. A process for preparing a mesoporous palladium-silver alloy electrocatalyst for efficient synthesis of cyclohexanone oxime according to claim 3, wherein the molar concentration of the ascorbic acid solution is 0.3 mol/L.
  10. 10. The application of the mesoporous palladium-silver alloy electrocatalyst in claim 1 is characterized in that the mesoporous palladium-silver alloy electrocatalyst is applied to synthesizing cyclohexanone oxime by electrochemical carbon-nitrogen coupling.

Description

Mesoporous palladium-silver alloy electrocatalyst for efficiently synthesizing cyclohexanone oxime, and preparation method and application thereof Technical Field The invention belongs to the technical field of catalysts, and particularly relates to a mesoporous palladium-silver alloy electrocatalyst for efficiently synthesizing cyclohexanone oxime, a preparation method and application thereof. Background Cyclohexanone Oxime (CYCO), an important precursor for the nylon industry to produce epsilon-caprolactam, is produced by the beckmann rearrangement of cyclohexanone oxime in an amount of more than 90% of epsilon-caprolactam worldwide. At present, two main methods exist in the industrial preparation of cyclohexanone oxime, one is a hydroxylamine method, the method needs high-temperature and high-pressure conditions, and explosive hydrogen, corrosive nitrogen oxide, sulfur dioxide and the like are used in the reaction process, so that the problems of high cost, poor environmental protection, high potential safety hazard and the like exist. The other is an ammoximation method, which is prepared by oxidizing ammonia with hydrogen peroxide to generate hydroxylamine and generating oximation reaction with cyclohexanone (CYC), wherein the hydrogen peroxide is unstable, and a large amount of hydrogen peroxide is generally needed, so that the problems of cost waste, catalyst deactivation and the like are caused. Electrocatalytic C-N coupling for the preparation of cyclohexanone oxime is receiving increasing attention as an alternative strategy. In principle, the currently accepted mechanism for the synthesis of electrocatalysis CYCO is that the nitrogen oxides are deoxygenated on the catalyst surface to form-NO, a multi-electron proton transfer process further occurs, a nucleophilic addition-elimination reaction of the key intermediate-NH 2OH,-NH2 OH with chemisorbed CYC is formed to yield CYCO, and the main competing reactions in the process are the over-hydrogenation of hydroxylamine, the reduction of CYC and hydrogen evolution. Thus, in designing the catalyst, it is desirable to achieve formation and stabilization of-NH 2 OH while C-N coupling has the highest priority. The development of the high-efficiency catalyst is not only matched with the chemisorption and activation of CYC and oxynitride, but also stabilizes an NH 2 OH intermediate and changes the chemical balance of the C-N coupling reaction. Transition metal catalysts are widely used for electrocatalytic C-N coupling due to their high adsorption and activation capacity for nitrogen oxides and carbonyl compounds. Currently, the corresponding metal catalysts are mainly focused on two types of material systems: A. The cost advantages of non-noble metal-based catalysts such as copper (Cu) and iron (Fe) based monoatomic or nano catalysts are obvious, but the problems of dissolution, agglomeration or chemical inactivation of catalytic active centers of the materials are not completely solved in long-term operation, especially in high-current density, strong acid or complex medium environments, the structural stability is challenging, and the technical problems of low Faraday Efficiency (FE), low yield and the like of electrosynthesis CYCO also exist due to excessive hydrogenation and competitive hydrogen evolution reaction of hydroxylamine. B. composite structure catalysts such as Covalent Organic Framework (COF) or Metal Organic Framework (MOF) supported nano-metal catalysts. The material can prepare ultrafine nano particles through a carrier confinement effect, but the intrinsic electronic conductivity of the material is generally low, and the charge transmission rate and the current density are seriously limited. In addition, long-term stability of the organic framework in electrochemical environments, leakage of metal nanoparticles, and mass transfer limitations of reactants within the micropores are all outstanding problems that limit practical applications. From the above analysis, there is a technical contradiction in the conventional technology that the non-noble metal catalyst with high activity faces a bottleneck of stability, thus low faraday efficiency and low yield, while the composite catalyst with adjustable structure is subject to conductivity and mass transfer capability. Therefore, the development of systematic design and action mechanism research of the high-efficiency synthesis CYCO electrocatalyst has become a core method for breaking through the technical bottleneck of CYCO electrosynthesis. Disclosure of Invention In order to solve the technical problems, the invention provides the mesoporous palladium-silver alloy electrocatalyst for efficiently synthesizing cyclohexanone oxime, the preparation method and the application thereof, and the catalyst is prepared by adopting a one-step soft template co-reduction method, so that the obtained catalyst has high electronic conductivity, high-efficiency charge transmission is ensured, no carrier