Preferential CO oxidation in hydrogen-rich stream over an electrochemically promoted Pt catalyst

We have conducted a Study on the preferential CO oxidation in hydrogen-rich stream (PROX) coupling catalysis and electrochemistry, i.e., by using an electrochemical catalyst (Pt/K-beta Al2O3). It was shown that PROX activity and selectivity of a Pt catalyst can be strongly enhanced by electrochemical pumping of potassium ions from the solid electrolyte support. The observed promotional effect was attributed to a decrease in the CO and H-2 chemisorption and to an increase in the O-2 chemisorption which led to a relative increase in the CO oxidation reaction vs. the H-2 oxidation. The electrochemical promotion allowed decreasing the operating temperature window of the Pt catalyst and attenuating the inhibiting effect of H-2 on both catalytic activity and selectivity. In addition some of the catalytic results were supported by in situ electrochemical characterization techniques such as cyclic voltammetry and open circuit potential measurements. Finally a very interesting permanent NEMCA effect was shown. It demonstrated the high stability of the formed promoting species and the potential for a further development of NEMCA effect in PROX real configurations. (C) 2009 Elsevier B.V. All rights reserved.