Nanostructured doped ceria is a prospective material for catalytic applications such as the construction of membranes with mixed electronic and ionic conductivity for effective syngas production. In this article, the surface properties of nanostructured ceria doped with praseodymium have been studied by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and Fourier transform infrared spectroscopy of adsorbed carbon monoxide. The effects of supporting 1.4 wt % Pt as well as structural changes upon the reduction of the samples with methane have been investigated. While in samples without supported platinum, mainly praseodymium cations are reduced in a methane atmosphere; stronger reduction of cerium cations was found in the case of surface modification with Pt. The structural differences correlate with results from temperature-programmed reaction experiments with methane. Explanations are discussed in terms of different reaction mechanisms.

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Abstract. Goethite, hematite and intermediate products of goetite thermal decomposition were studied by IR and Raman spectroscopy to identify these products used as catalysts of some chemical reactions. The presence of a small number of OH-groups in the products of the decomposition up to 900-1000 ~ C was supposed to hinder the formation of perfect hematite structure. The hypothesis concerning C6v space group of protohematite indistinguishable from D36a space group of hematite by X-Ray diffraction was suggested. This hypothesis explains both the additional lines in IR and Raman spectra compared to hematite spectra and the same position of peaks in X-Ray diffraction picture.