A novel inverse CeO(2)/CuO catalyst for preferential oxidation of CO in H(2)-rich stream (CO-PROX) has been developed on the basis of a hypothesis extracted from previous work of the group (JACS 2007, 129, 12064). Possible separation of the two competing oxidation reactions involved in the process (of CO and H(2), respectively) is the key to modulation of overall CO-PROX activity and is based on involvement of different sites as most active ones for each of the two reactions. Achievement of large size CuO particles and adequate CeO(2)-CuO interfacial configurations in the inverse catalyst apparently allows appreciable enhancement of the catalytic properties of this kind of system for CO-PROX, constituting an interesting alternative to classic direct configurations so far explored for this process. Reasons for such behavior are analyzed on the basis of operando-XRD, -XAFS, and -DRIFTS studies.

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A ceria-supported copper oxide catalyst has been examined with respect to interaction with CO by means of CO-TPR tests employing a DRIFTS cell as reactor. Parallel analysis of isotopic shifts in the DRIFTS spectra obtained upon interaction of the catalysts with either 12CO or 13CO allows unambiguous assignment of the various carbonyl and carbonate-type species formed. The study is complemented by separate examination of the stability of carbonyl species focused to get hints on the nature of CO adsorption centers at the catalyst surface. Joint analysis of gases evolution during the CO-TPR tests and DRIFTS spectra is employed to determine the nature of processes taking place during such tests. Additionally, analysis of the various CO2 isotopes evolving during the course of a TPO run subsequent to 13CO-TPR test is employed to discard the occurrence of CO disproportionation upon interaction of the catalyst with CO up to 400 °C.