Relationship between structure and CO oxidation activity of ceria-supported gold catalysts.
Gold catalysts supported on cerium oxide were prepared by solvated metal atom dispersion (SMAD), by deposition-precipitation (DP), and by coprecipitation (CP) methods and were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). The catalytic activity was tested in the CO oxidation reaction. The structural and surface analyses evidenced the presence of a modified ceria phase in the case of the DP sample and the presence of pure ceria and gold metal crystallites in the case of the SMAD and CP samples. The DP sample, after a mild treatment in air at 393 K, exhibited only ionic gold, and it was very active below 273 K. By comparing the activities of the different catalysts, it is suggested that the presence of small gold particles, as obtained by the SMAD technique, is not the main requisite for the achievement of the highest CO conversion. The strong interaction between ionic gold and ceria, by enhancing the ceria surface oxygen reducibility, may determine the particularly high activity.
Venezia
Anna Maria
AM
Istituto per lo Studio dei Materiali Nanostrutturati, CNR, Via Ugo La Malfa 155, 90146 Palermo, Italy. anna@pa.ismn.cnr.it
Pantaleo
Giuseppe
G
Longo
Alessandro
A
Di Carlo
Gabriella
G
Casaletto
Maria Pia
MP
Liotta
F Leonarda
FL
Deganello
Giulio
G