Effect of SO2 on Catalytic CO Oxidation Over Nano-Structured, Mesoporous Au/Ce1−xZrxO2 Catalysts

A series of nano-structured, mesoporous Au/Ce1 - xZrxO2 type catalysts were synthesized by first synthesizing Ce1-xZrxO2 type of support with different degree of Zr substitutions and following sol-gel route. One weight percent of Au was incorporated on these supports using deposition-precipitation method. These synthesized catalysts were characterized in detail by various techniques, and evaluated for their CO oxidation activity. Effect of SO2 poisoning on catalytic CO oxidation activity was also investigated in detail. It was observed that the catalytic activity for CO oxidation reaction depends on the Ce/Zr molar ratio. The effect of SO2 on CO oxidation was less prominent for the Zr incorporated 'Au/Ce0.8Zr0.2O2 (ACZ0.2)' as compared to bare 'Au/CeO2 (AC)' catalyst. In case of ACZ0.2, the activity remains quite stable even after 5 h of SO2 exposure, however, after 12 and 18 h, the activity decreases to 62 and 55%, respectively. Whereas AC catalyst shows rapid decline in catalytic activity from the first hour of SO2 exposure, and continue to decline significantly to 35 and 18% after 12 and 18 h of SO2 exposure, respectively. Multiple regeneration studies of both bare and Zr incorporated catalysts show pronounced improvement/regain in catalytic activity.