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CN-122013223-A - Bimetallic MOFs catalyst for synthesizing ammonia through electrocatalytic nitrate reduction and preparation method and application thereof

CN122013223ACN 122013223 ACN122013223 ACN 122013223ACN-122013223-A

Abstract

The invention relates to a bimetallic MOFs catalyst for synthesizing ammonia by electrocatalytic nitrate reduction, and a preparation method and application thereof, wherein the bimetallic MOFs catalyst takes quinoline-5-carboxylic acid as a ligand and has Cu and Co bimetallic active sites; hydrophobic carbon paper is used as a carrier and is used as a cathode in an electrocatalytic nitrate reduction synthesis ammonia system. The catalyst of the invention has the Faraday efficiency of producing ammonia up to 96.4% under the condition of neutral electrolyte minus 0.6V RHE , can realize the efficient degradation of NO 3 ‑ and the recycling of ammonia, has simple preparation process, low cost and mild reaction condition, and has remarkable industrial application prospect.

Inventors

  • QIAO JINLI
  • LI WENYU
  • QIAO HUITING

Assignees

  • 东华大学

Dates

Publication Date
20260512
Application Date
20260128

Claims (10)

  1. 1. A bimetallic MOFs catalyst for electrocatalytic nitrate reduction synthesis of ammonia is characterized in that quinoline-5-carboxylic acid is used as a ligand of the bimetallic MOFs catalyst, cu and Co bimetallic active sites are provided, and hydrophobic carbon paper is used as a carrier of the bimetallic MOFs catalyst and is used as a cathode in an electrocatalytic nitrate reduction synthesis ammonia system.
  2. 2. A preparation method of a bimetallic MOFs catalyst for synthesizing ammonia by electrocatalytic nitrate reduction comprises the following steps: Co (NO 3 ) 3 ·6H 2 O and Cu (NO 3 ) 2 ·3H 2 O) are mixed, quinoline-5-carboxylic acid is added and dissolved in a mixed solvent of dimethylformamide and absolute ethyl alcohol, the mixed solution is subjected to continuous ultrasonic treatment at room temperature, then solvothermal reaction is carried out, and the mixed solution is cooled, washed and dried to prepare the bimetallic MOFs catalyst.
  3. 3. The preparation method of claim 2, wherein the molar ratio of quinoline-5-carboxylic acid to Cu (NO 3 ) 2 ·3H 2 O：Co(NO 3 ) 3 ·6H 2 O is 2:0.1-2), and the volume ratio of dimethylformamide to absolute ethyl alcohol in the mixed solvent is 1:1.
  4. 4. The preparation method according to claim 2, wherein the power of the ultrasonic treatment is 53-80W, the ultrasonic time is 15-30 min, the temperature of the mixed solution in the ultrasonic process is controlled to be 15-30 ℃, the solvothermal reaction temperature is 100-120 ℃, and the reaction time is 24-60 hours.
  5. 5. The use of the bimetallic MOFs catalyst of claim 1 in electrocatalytic reduction of nitrate to ammonia, wherein the use comprises supporting the bimetallic MOFs catalyst on hydrophobic carbon paper as a cathode in an electrocatalytic system.
  6. 6. The method according to claim 5, wherein the electrocatalytic reaction is carried out in an H-type electrolytic cell, wherein a bimetallic MOFs catalyst loaded on hydrophobic carbon paper is used as a cathode, a platinum sheet is used as an anode, an Ag/AgCl electrode filled with saturated KCl solution is used as a reference electrode, an anolyte is Na 2 SO 4 solution, a catholyte is NaNO 3 + Na 2 SO 4 solution, nafion117 is used as a diaphragm, and the working potential is-0.4 to-0.8V RHE .
  7. 7. The use according to claim 6, wherein the concentration of NaNO 3 in the catholyte is 0.05-0.2 mol/L, the concentration of Na 2 SO 4 is 0.1-0.3 mol/L, the electrocatalytic reaction temperature is 20-35 ℃, and the reaction lasts for 2-12 hours.
  8. 8. The use according to claim 5, wherein the specific step of loading the bimetallic MOFs catalyst on hydrophobic carbon paper comprises: (1) Firstly, immersing carbon paper into polytetrafluoroethylene solution with the mass concentration of 10% -30%, drying in an oven, and then roasting in a muffle furnace to obtain hydrophobic carbon paper; (2) And adding the bimetallic MOFs catalyst into a mixed system of isopropanol and Nafion solution, performing ultrasonic treatment to obtain catalyst slurry, and then spraying the catalyst slurry on the surface of hydrophobic carbon paper to obtain the supported bimetallic MOFs catalyst.
  9. 9. The application of the method according to claim 8, wherein the drying temperature of the carbon paper in the drying oven in the step (1) is 50-70 ℃, the drying time is 1-3 hours, the roasting temperature of the muffle furnace is 100-115 ℃, the roasting time is 24-48 hours, and the heating rate is 5-20 ℃ per minute.
  10. 10. The use according to claim 8, wherein the loading of the catalyst slurry in step (2) on the surface of the hydrophobic carbon paper is 1.5-3.5 mg/cm 2 .

Description

Bimetallic MOFs catalyst for synthesizing ammonia through electrocatalytic nitrate reduction and preparation method and application thereof Technical Field The invention belongs to the technical field of electrocatalytic nitrate radical reduction ammonia synthesis, and particularly relates to a bimetallic MOFs catalyst for electrocatalytic nitrate radical reduction ammonia synthesis, and a preparation method and application thereof. Background Ammonia (NH 3) is not only an important chemical raw material and fertilizer, but also a novel energy substance which has great development potential, does not contain carbon elements and has high energy density. Therefore, the adoption of a novel, green and efficient ammonia production process has become a development trend conforming to modern sustainable and health. The production of industrial NH 3 has so far mainly relied on the Haber-Bosch process with century history, which takes high purity hydrogen (H 2) and nitrogen (N 2) as raw materials to react under the conditions of iron catalyst and high temperature (400-600 ℃) and high pressure (20-40 MPa). This not only results in significant consumption of fossil fuels and carbon dioxide (CO 2) emissions, but also its harsh reaction conditions and lower conversion are critical to limit industry development. The electrocatalytic reduction nitrate radical reaction (NO 3 RR) with the advantages of high efficiency, environmental friendliness and the like adopts nitrate radical (NO 3-) as a raw material, has high solubility of NO 3- and low dissociation energy (204 kJ mol -1), and effectively reduces mass transfer resistance and reaction energy barrier when NO 3- is converted into NH 3 through an electrochemical way under mild reaction conditions. In addition, the NO 3 RR can realize the nitrate synergistic treatment of industrial wastewater and polluted groundwater. However, in the absence of a catalyst, the rate of reaction and Faradaic Efficiency (FE) of NO 3 RR are doubly limited by chemical inertness and competing hydrogen evolution reactions in the aqueous electrolyte, making the NO 3 RR process slower. In order to improve the yield and efficiency of synthesizing ammonia, a reasonable design of a catalyst for electrocatalytic reduction of nitrate radical is required, which is a difficult point and a technical breakthrough point in the research direction. To date, many open studies have demonstrated that noble metal nanoparticles, such as ruthenium, rhodium, palladium, etc., can effectively enhance the performance of electrochemical NH 3 synthesis. However, the scarcity and high price greatly limit their large-scale application. Therefore, development of low-priced and resource-rich transition metal nanoparticulate iron (Fe, co, ni, and Cu) has become an important research direction. In the non-noble metal catalyst, the Cu-based nano material has great application potential due to the fact that the electronic structure of the Cu-based nano material is matched with the molecular orbit of NO 3-. The common massive Cu-based nano material has low metal utilization rate due to the inertia of internal atoms, so that the consumption of copper resources is increased. Therefore, improving the utilization efficiency of copper atoms by strategies such as morphological engineering and surface loading has become one of the core means of research. The Metal Organic Frameworks (MOFs) material has the characteristics of adjustable porous structure, high specific surface area, good metal site dispersibility and the like, is an ideal carrier for constructing the high-efficiency electrocatalyst, can form double metal MOFs by doping hetero metal atoms, and can regulate and control the electronic state, the energy band structure and the intermediate adsorption energy so as to realize the synergistic effect of active sites. However, the application of the existing bimetal MOFs in NO 3 RR still has the problems of complex preparation process, insufficient degradation and ammonia production efficiency of low-concentration NO 3- under neutral conditions and the like, and is difficult to meet the industrial application requirements. Therefore, it is necessary to design a bimetallic MOFs catalyst with simple synthesis process, and meanwhile, the degradation efficiency and the ammonia production rate of low-concentration NO 3- under neutral conditions are improved, so that the bimetallic MOFs catalyst has important significance in promoting the bimetallic MOFs catalyst to be applied to the field of electrocatalytic nitrate reduction ammonia synthesis in a large scale. Disclosure of Invention The invention aims to solve the technical problem of providing a bimetallic MOFs catalyst for synthesizing ammonia by electrocatalytic nitrate reduction, and a preparation method and application thereof, so as to realize efficient electrocatalytic degradation of NO 3- in industrial wastewater and polluted groundwater, realize high-selectivity conve