Promoting the preferential oxidation of Co by altering the reducibility of Pt

The promotion of Pt/Al2O3 with niobia (Nb2O5) was studied during the preferential oxidation of CO in the presence hydrogen (PROX reaction). CO conversion vs. temperature on 1% Pt/x% Nb-Al2O3 (x = 0, 1, 5, 10, 20) catalysts, showed that at lower Nb loading the activity increased. When yields were compared, a maximum of 65% CO2 produced was obtained for the 5% Nb-promoted catalyst. As Nb loading increased, the decoration effect also increased and bigger aggregates of NbOx were formed. The same Pt particle size gave lower H2 adsorption when Nb loading increased. When 1% Pt was supported on Nb2O5, the CO conversion was very low in the PROX reaction, but when only CO and O2 were reacting, the typical CO ignition behavior on Pt catalysts was observed. In contrast, when H2 was absent, the CO oxidation activity was restored. The addition of niobia to Pt/Al2O3 catalysts enhanced the catalytic activity on the PROX of CO. This is an abstract of a paper presented at the AIChE Annual Meeting (San Francisco, CA 11/12-17/2006).