Use of the differential charging effect in XPS to determine the nature of surface compounds resulting from the interaction of a Pt/(BaCO3 + CeO2) model catalyst with SO (x)

作者：Smirnov M Yu^*; Kalinkin A V; Dubkov A A; Vovk E I; Sorokin A M; Nizovskii A I; Carberry B; Bukhtiyarov V I

来源：Kinetics and Catalysis, 2011, 52(4): 595-604.

DOI：10.1134/S0023158411040161

Changes in the chemical composition of the surface of a Pt/(BaCO3 + CeO2) model NO (x) storage-reduction catalyst upon its interaction with SO (x) (SO2 (260 Pa) + O-2 (2600 Pa) + H2O (525 Pa)) followed by regeneration in a mixture of CO (2100 Pa) with H2O (525 Pa) were studied by X-ray photoelectron spectroscopy (XPS). Model catalyst samples were prepared as a thin film (about several hundreds of angstrom units in thickness) on the surface of tantalum foil coated with a layer of aluminum oxide (similar to 100 ). It was found that the Pt/BaCO3 and Pt/CeO2 catalyst constituents acquired different surface charges (differential charging) in the course of photoelectron emission; because of this, it was possible to determine the nature of surface compounds formed as a result of the interaction of the catalyst with a reaction atmosphere. It was found that barium carbonate was converted into barium sulfate as a result of reaction with SO (x) on the surface of BaCO3 at 150A degrees C. As the treatment temperature in SO (x) was increased to 300A degrees C, the formation of sulfate on the surface of CeO2 was observed. The sulfatization of CeO2 was accompanied by the reduction of Ce(IV) to Ce(III). The regeneration reaction of the catalyst treated in SO (x) at 300A degrees C resulted in the consecutive decomposition of cerium(III) sulfate at a parts per thousand currency sign500A degrees C and then barium sulfate at 600-700A degrees C. Upon the decomposition of BaSO4, a portion of sulfur was converted into a sulfide state, probably, because of the formation of BaS.

• 出版日期2011-7