CO selective oxidation using Co-promoted Pt/γ-Al2O3 catalysts

In this work, alumina-supported platinum catalysts promoted with cobalt were analyzed in the preferential CO oxidation (PROX) reaction. The addition of Co represents a significant catalytic improvement with regard to the monometallic Pt catalyst. This improvement reaches its maximum with a Co/Pt atomic ratio of 1.5. The addition of a higher level of cobalt decreases the activity probably because it would produce the coverage of the Pt active sites, thus inhibiting the adsorption of CO. For all the bimetallic catalysts, the maximum conversion occurs at ca. 130 °C, a value which is within the acceptable working range for this process. A further temperature increase generates a decrease in the CO conversion. The studied catalysts presented a slight deactivation after several hours on stream. The original activity is recovered by submitting the catalysts to a reduction process at 500 °C. Results are explained in terms of TPR, DRS, EXAFS and XANES characterization of the catalysts.