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-.
Scopus Subject Areas
- Environmental Science(all)
- Process Chemistry and Technology
- NO decomposition
- Redox action