SURFACE-CHLORINATED CERIA AND CHLORINE-CONTAINING REDUCED PD CEO2 CATALYSTS - A FTIR STUDY/

Adsorption of CO, used as infrared molecule probe, was performed at ro om temperature or at low temperature (140 K), on either chlorine-free or chlorine-containing ceria, in order to investigate both the chlorin e effect and the ceria reduction state. On ceria and Pd/ceria catalyst s, chlorine acts as an electronegative ligand. Its effect extends to t he raft-like structure of palladium in Pd/CeO2 catalysts. Moreover, ce ria chlorination prevents palladium from CO clustering. CO adsorption on the chlorine-containing Pd/CeO2 catalyst led to some water formatio n, tentatively assigned to an incomplete reduction of microporous ceri a sites. Moreover, oxalate-like species were evidenced and considered as impurities on residual reduced carbonate sites.