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 Cu2+δ⇔Cu2+⇔Cu2−δ over the fresh sample and that amongst Cu1+δ⇔Cu+⇔Cu1−δ over the reduced sample are essential for N2O decomposition. Species such as N2O22−, O2−, O22−, NO3−, NO2−, and [NO2O2]2− are generated during N2O decomposition. The key step is the decomposition of N2O22−.