2020 Volume 63 Issue 3 Pages 158-162
The mechanism of NO adsorption on CeO2 and the effects of O2, CO2, and H2O were studied by in-situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS). NO species were adsorbed on CeO2 to form anionic nitrosyl groups. Formation of these anionic nitrosyl (–NO−) groups was associated with degradation of bidentate carbonate species and peak shift of the surface hydroxyl groups, indicating competitive adsorption of NO with CO2 and interaction of –NO− with hydroxyl groups. Evaluation of the changes in anionic nitrosyl groups in the presence and absence of O2, CO2, and H2O showed that co-flow of O2 promoted NO adsorption whereas co-flow of CO2 or H2O suppressed NO adsorption, which supports the competitive adsorption mechanism of NO with CO2 and H2O. The competitive adsorption mechanism suggests that degradation of CeO2 by NO adsorption will be small in a gas mixture with high contents of H2O and CO2.