X-ray photoelectron spectroscopic study of the interaction of supported metal catalysts with NOx

The reactions of the platinum and rhodium model catalysts applied to aluminum oxide with NOx (10 Torr NO + 10 Torr O-2) were studied by X-ray photoelectron spectroscopy. The reaction conducted at room temperature formed on the surface of the oxide support the NO3,s- nitrate ions characterized by the N1s line at 407.4 eV and O1s line at 533.1 eV and the NO2,s- nitrite ions characterized by the N1s line with a binding energy of 404.7 eV. At the same time, the Pt4f and Rh3d lines of the supported platinum particles are shifted toward higher binding energies by 0.5-1.0 eV and 0.7-1.2 eV, respectively. It is assumed that the binding energies increase due to changes in the chemical state of the platinum metal in which oxygen is dissolved. The reaction of NOx with Pt/Al2O3 at 200 degrees C forms platinum oxide defined by the Pt4f (7/2) line with a binding energy of 72.3 eV.