화학공학소재연구정보센터
Catalysis Letters, Vol.70, No.3-4, 131-135, 2000
Effect of SO2 on the oxygen storage capacity of ceria-based catalysts
We have examined the effect of SO2 poisoning on a series of catalysts having Pd supported on ceria, alumina, and ceria-zirconia. For pre-exposure of 20 ppm SO2 at 673 K. we observed no changes in the light-off curves for CO oxidation on Pd/alumina. This pre exposure of SO2 to Pd/ceria resulted in a significant upward shift in the light-off curve, so that the poisoned Pd/ceria catalyst exhibited similar rates to that of Pd/alumina. Similar upward shifts were observed for the water-gas-shift reaction upon exposure of Pd/ceria or Pd/ceria-zirconia samples to SO2. However, pulse-reactor data with alternating CO and O-2 pulses showed that SO2 poisoning actually increased the amount of oxygen that could be transferred to and from the catalyst over the entire temperature range that was examined. The implication of these results for understanding the effect of SO2 poisoning and the measurement of OSC are discussed.