A study on the decomposition of N₂O over YBa₂CU₃O₇

YBa₂Cu₃O₇ was prepared by means of the citric acid complexing method. The catalytic performances of N₂O decomposition over fresh and 250°C-reduced YBa₂Cu₃O₇ have been evaluated. Techniques such as XRD, TGA, XPS, EPR, TPD, pulsing, in-situ DRIFT, and FT-Raman were employed to investigate the natures of active sites and to identify the possible reaction intermediates. A catalytic reaction mechanism has been proposed. The N₂O decomposition activity over the fresh YBa₂Cu₃O₇ is lower than that over the reduced one. Being reduced at 250°C in H₂, YBa₂Cu₃O₇ transformed from an orthorhombic to a tetragonal structure in which there were Cu²⁺, Cu⁺, and oxygen vacancies. The redox action amongst Cu^2+δ⇔Cu²⁺⇔Cu^2-δ over the fresh sample and that amongst Cu^1+δ⇔Cu⁺⇔Cu^1-δ over the reduced sample are essential for N₂O decomposition. Species such as N₂O₂^2-, O₂^-, O₂^2-, NO₃^-,NO₂^-, and [NO₂O₂]^2- are generated during N₂O decomposition. The key step is the decomposition of N₂O₂^2-.