Effect of LaFeO3 Decoration and Ozone Treatment on Thermal Stability of Au/Al2O3 for CO Oxidation

The 1.1%Au/LaFeOx/Al2O3 catalysts were prepared by the iso-volume impregnation method and activated with H2 or O3. The catalytic performance for CO oxidation at room temperature was investigated by accelerated deactivation tests in 1.0% CO reactant stream at 550 °C. The introduction of La and Fe enhanced the thermal stability of Au/Al2O3 with a decrease in initial activity, probably due to the formation of LaFeO3 perovskite on the Al2O3 surface. The 1.1%Au/2%LaFeO3/Al2O3 catalyst activated by H2 can transform 65% CO into CO2 at room temperature after pretreatment in 1.0% CO reactant stream at 550 °C for 2 h, whereas 1.1%Au/Al2O3 activated by H2 totally loses its activity. O3 activation can always make 1.1%Au/LaFeO3/Al2O3 more active than that of H2 activation during the pretreatment process in 1.0% CO. After pretreatment for 10 h, 1.1%Au/2%LaFeO3/Al2O3 activated by O3 still shows 40% conversion of 1.0% CO at room temperature, whereas those activated by H2 become inactive completely. The better thermal stability of the catalysts activated by O3 may be due to that O3 activation leads to the formation of partially oxidized state of Au in Au/FLA-O3, which may reinforce the interaction between the metal and support.