Preferential oxidation of CO in presence of H2 behavior OF PtSn/γ -Al2O3 catalysts modified by K or Ba

the behavior of catalysts based on pt/γ-al2o3 is analyzed in the co oxidation reaction. experiments were performed in the temperature range between 50°c and 250°c with a feed h2 rich, and a concentration of 1% co and 0.6% o2 catalysts studied were: monometallic pt/γ-al2o3, bimetallic ptsn/γ-al2o3 with a ratio sn/pt=1.6 at/at and two catalysts prepared by modification of the last one with k or ba. the catalyst that showed maximum activity and selectivity levels is the ptsnk/γ-al2o3. the tin addition increases the activity which allows the reaction to occur at lower temperatures due to the decrease in the co-pt interaction. the addition of k or ba produces a subsequent improvement with respect to the co oxidation temperature, which leads to a selectivity increase. the selectivity of the co oxidation passes through a maximum value as a function of the temperature. this maximum is explained by the importance acquired by the reverse of water gas shift reaction at temperatures near 200oc.