Recent progresses on the use of supported bimetallic catalysts for the preferential oxidation of CO (PROX) Check Access

The preferential oxidation of CO in the presence of a large excess of H₂ can be used as a purification technique to obtain PEM fuel cell-grade H₂. Improvements of the catalyst performances at low temperature are yet required in terms of specific activity, selectivity and stability. Several bimetallic compounds were shown to exhibit much improved PROX performances as compared to the monometallic counterparts. The improved activity of alloys and bimetallic can be due to geometric or electronic effects. The present review discusses these matters giving a special attention to in situ IR-based studies realized over Pt-based formulations, since CO is both a reactant and a molecular probe enabling the determination of the state of metals under reaction conditions. The need to study the catalysts under relevant operating conditions is emphasized. In situ and operando conditions enable determining the nature of the true active phases, because alloy segregation can readily occur even upon some minor modification of the experimental conditions.