A. Elhamdaoui et al., CO AND NO INTERACTION WITH PD-AG AND PD-CR BIMETALLIC CATALYSTS .1. X-RAY-DIFFRACTION, INFRARED-SPECTROSCOPY, AND THERMOREACTION, Journal of catalysis, 148(1), 1994, pp. 47-55
Well-defined Pd-based bimetallic catalysts have been prepared and char
acterized. X-ray diffraction shows that in Pd-Ag, Ag has a strong tend
ency to segregate at the surface of the catalyst. On the other hand, i
n Pd-Cr, Cr is well distributed in the network of Pd and induces an el
ectronic structure modification of Pd. The adsorption and coadsorption
of CO and NO on these solids were studied by infrared spectroscopy an
d thermodesorption and compared with similar adsorptions on pure palla
dium and rhodium. It was shown that although the adsorption energies o
f CO and NO on the various catalysts are similar, upon coadsorption of
the two reactants the surface coverage by NO is 4 to 20 times larger
than by CO. Silver decreases this CO coverage and chromium slightly in
creases it. When a thermoreaction is performed at 430 K, appreciable a
mounts of N2 and CO2 are evolved from Pd, Pd-Cr, and Rh catalysts; Pd-
Cr is more reactive than Pd and Pd-Ag is unreactive. (C) 1994 Academic
Press. Inc.