An FTIR study on the formation of NCO surface complexes over Rh/CeO2

Abstract Fourier transferred infrared spectroscopy combined with mass spectrometry was used to follow the NO + CO reaction and the formation of adsorbed species. It was shown that when the reaction between NO and CO set in two absorption bands appeared in the FTIR spectra of Rh/CeO 2 at 2180 and 2210 cm −1 , which were not observed following the adsorption of reactants and products. Adsorption of HNCO on pure CeO 2 at 200 and 300 K yielded the same spectral features suggesting that these bands belong to adsorbed isocyanate, NCO, species bonded to the CeO 2 . These results suggest that the spillover process of NCO from the Rh onto support proceeds even in the case of CeO 2 used as a solid oxidizer in the three-way catalyst. NCO attached to ceria reacts with H 2 O resulting in the release of NH 3 .