CO adsorption on cerium-based oxide-supported gold catalysts

2 CO adsorption on cerium-based oxide-supported gold catalysts 

CO adsorption on gold has been intensively investigated on single crystals ° and small nanoparticles supported on both planar and powdered oxi- 

In accordance with the considerations above, it is obvious that an in-depth analysis of CO adsorption for cerium-based oxide-supported gold catalysts represents a very challenging issue, which requires first, the identification of the nature of the main CO forms occurring on the surface of both the metal phase and the support, and second, the quantitative establishment of the contribution of each of these forms to the total amount of adsorbed CO. As will be discussed below in some detail, these goals have been successfully achieved in a series of recently published studies in which the chemisorption of CO on catalysts consisting of gold nanoparticles supported on ceria-zirconia mixed oxides was investigated. 

Regarding the nature of CO adsorbed forms, the curves (a) in Fig. 2.21 show FTIR spectra recorded at 298 K under P o = 100 torr, for the bare support (left) and the corresponding Au/CZ catalyst (right). As discussed in Collins et an analysis of these spectra allowed the authors to identify three main species. One of them, which is characterized by an absorption band at 2110 cm 

The third form of chemisorbed CO, characterized by bands in the 1800-1200 cm region of the spectra shown on the right of Fig. 2.21, is associated with carbonate species resulting from the CO/CZ interaction. In contrast to the forms mentioned above, these carbonate species are only very slightly modified by the 30 min evacuation treatment at 298 K They are referred to as irreversible forms of chemisorbed CO. 

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