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CN-122013222-A - Tungsten oxide supported ruthenium oxide catalyst, preparation method thereof and application thereof in thermo-catalytic synthesis of ammonia

CN122013222ACN 122013222 ACN122013222 ACN 122013222ACN-122013222-A

Abstract

The invention provides a tungsten oxide supported ruthenium oxide catalyst, a preparation method thereof and application thereof in thermo-catalytic synthesis of ammonia, wherein the catalyst comprises an oxygen-enriched vacancy WO 3‑x carrier and RuO 2 nano-particle active component, ruO 2 is anchored through oxygen vacancies in the WO 3‑x carrier to form a Ru-O-W interface structure, and the mass fraction of RuO 2 in the catalyst is 0.05 wt-5 wt%. The ruthenium-containing composite material is obtained by impregnating a WO 3−x carrier with ruthenium salt and carrying out high-temperature annealing treatment under the protection of inert atmosphere. The active component Ru is firmly anchored by utilizing the electron capturing effect of oxygen vacancies, and the formed strong interface interaction can effectively inhibit migration and agglomeration of metal nano particles in a high-temperature environment, and simultaneously, the solubility and activity of nitrogen in the electrolyte are obviously improved by combining a high-temperature high-pressure electrochemical reaction system. The ammonia production rate under the high-temperature and high-pressure condition is up to 319.45 mu g (mu g) −1 ⋅h −1 , the Faraday efficiency is 15.53%, the structural stability and the catalytic activity are excellent, and a new technical approach is provided for high-efficiency electrocatalytic synthesis of ammonia.

Inventors

  • WU TAO
  • ZHAO XU
  • LU ANHUI

Assignees

  • 大连理工大学

Dates

Publication Date
20260512
Application Date
20260320

Claims (10)

  1. 1. A tungsten oxide supported ruthenium oxide catalyst is characterized by comprising a WO 3-x carrier and RuO 2 nano particle active components, wherein the RuO 2 nano particles are anchored through oxygen vacancies in the WO 3-x carrier to form a Ru-O-W interface structure, the catalyst does not have an oxygen vacancy EPR signal, and the mass fraction of the RuO 2 nano particle active components in the catalyst is 0.05 wt to 5 wt%.
  2. 2. A method for preparing a tungsten oxide supported ruthenium catalyst according to claim 1, comprising the following steps: (1) Dropwise adding the ruthenium salt water solution into the WO 3-x carrier, and loading ruthenium element by an impregnation method to enable the ruthenium component to be loaded on oxygen vacancy defect sites on the surface of the carrier; (2) And (3) placing the dried solid in a tubular furnace, performing high-temperature annealing treatment under the protection of inert atmosphere, and constructing a Ru-O-W interface structure by utilizing the anchoring action of oxygen vacancies to obtain the RuO 2 /WO 3-x catalyst.
  3. 3. The method of claim 2, wherein the ruthenium salt in step (1) comprises one or more of ruthenium trichloride, ruthenium nitrosonitrate and ruthenium acetylacetonate.
  4. 4. The process according to claim 2, wherein the concentration of the ruthenium salt in the step (1) is 0.02 to 0.4 mol/L.
  5. 5. The method of claim 2, wherein the annealing temperature in the step (2) is 300 to 500 ℃.
  6. 6. The preparation method of the WO 3-x carrier in the step (1) is characterized in that tungsten salt is dissolved in absolute ethyl alcohol, the tungsten salt is stirred uniformly and then transferred into a hydrothermal reaction kettle to carry out solvothermal reaction, and after the reaction is finished, the carrier is centrifuged, washed and dried to obtain the deep blue oxygen-enriched vacancy WO 3-x carrier.
  7. 7. The process according to claim 6, wherein the mass to volume ratio of the tungsten salt to the absolute ethanol is 0.1-5 g/40 mL, and/or, The tungsten salt comprises one or more of tungsten hexachloride, sodium tungstate and ammonium metatungstate.
  8. 8. The method of claim 6, wherein the solvothermal reaction is carried out at 160-200 ℃ for 12-24 hours.
  9. 9. Use of the catalyst of claim 1 in the thermocatalytic synthesis of ammonia.
  10. 10. The process according to claim 9, wherein the reaction temperature is 100 to 250℃and the reaction pressure is 10 to 50bar.

Description

Tungsten oxide supported ruthenium oxide catalyst, preparation method thereof and application thereof in thermo-catalytic synthesis of ammonia Technical Field The invention belongs to the technical field of electrocatalytic synthesis of ammonia, relates to a tungsten oxide supported ruthenium catalyst, a preparation method thereof and application thereof in the electrocatalytic synthesis of ammonia, and in particular relates to a preparation method of a tungsten oxide supported ruthenium oxide (RuO 2/WO3) catalyst with oxygen-enriched vacancies and application thereof in the electrocatalytic nitrogen reduction (NRR) synthesis of ammonia under high-temperature and high-pressure conditions. Background Ammonia is one of the chemical industries with the greatest global yield and is indispensable in the fields of agrochemicals, chemical raw materials, clean energy carriers and the like. Although the traditional Haber-Boshi method has been used for hundreds of years, the severe conditions of high temperature and high pressure cause energy consumption to account for 1% -2% of global total energy consumption, and the global greenhouse gas emission of about 1.5% is contributed, so that the realization of sustainable development is severely restricted. Therefore, development of an ammonia synthesis technology that is green and low in energy consumption is urgent. Electrocatalytic nitrogen reduction (NRR) technology is considered as a very potential alternative technology because of its ability to achieve "zero carbon" ammonia production under mild conditions using renewable energy sources. However, conventional normal temperature and pressure piezocatalysis NRR suffers from serious bottlenecks, firstly, the extremely low solubility of nitrogen in aqueous solution, resulting in insufficient concentration of N 2 at active sites and slow mass transfer kinetics, and secondly, the extremely competitive Hydrogen Evolution Reaction (HER) in aqueous electrolyte, resulting in generally low Faraday Efficiency (FE) and yield of synthetic ammonia. Studies have shown that increasing the reaction temperature and pressure can significantly increase nitrogen solubility and accelerate activation of n≡n bonds, but this places higher demands on the stability of the catalyst. Ruthenium is considered as a recognized active metal for synthesizing ammonia and is capable of effectively adsorbing and activating nitrogen molecules, tungsten oxide is usually used as a carrier, but under the environment of high temperature hydrothermal (such as 250 ℃), a supported metal catalyst faces serious challenges that metal nano particles have extremely high surface energy, are easy to migrate and agglomerate under high temperature driving, are easy to oxidize into metal oxide, lead to active site loss and rapidly attenuate catalytic performance. The traditional physical loading method is difficult to meet the stability requirement of the high-temperature high-pressure electrochemical process. Therefore, developing a catalyst with a strong interaction interface, capable of locking active metal sites and resistant to high temperature and high pressure impact is a key problem for the current high temperature electrocatalytic synthesis of ammonia. Disclosure of Invention Aiming at the problems, the invention provides a tungsten oxide supported ruthenium oxide catalyst, a preparation method thereof and application thereof in thermo-catalytic synthesis of ammonia. Oxygen vacancies are introduced in situ through an alcohol thermal method for anchoring Ru substances, and a subsequent high-temperature annealing process is combined to prepare the WO 3-x -loaded RuO 2 nano-particle catalyst, which has extremely high activity and stability under the high-temperature and high-pressure environment of the thermo-electric catalytic synthesis ammonia. In order to achieve the above purpose, the invention adopts the following technical scheme: a tungsten oxide supported ruthenium oxide catalyst, which comprises an oxygen-enriched vacancy WO 3-x carrier (x represents oxygen vacancy) and RuO 2 nano particle active components, wherein RuO 2 nano particles are anchored through the oxygen vacancy in the WO 3-x carrier to form a Ru-O-W interface structure, the catalyst does not have an oxygen vacancy EPR signal, and the mass fraction of the RuO 2 nano particles in the catalyst is 0.05-wt percent to 5 wt percent. The tungsten element in the carrier is hexavalent. The invention also provides a preparation method of the tungsten oxide supported ruthenium catalyst, which comprises the following steps: (1) Dropwise adding the ruthenium salt water solution into the WO 3-x carrier, and loading ruthenium element by an isovolumetric impregnation method to load ruthenium components on oxygen vacancy defect sites on the surface of the carrier; (2) And (3) placing the dried solid in a tubular furnace, performing high-temperature annealing treatment under the protection of inert atmosphere,