Reduction of NO by CO using Pd-CeTb and Pd-CeZr catalysts supported on SiO2 and La2O3-Al2O3

The catalytic activity of Pd catalysts supported on Ce_0.73Tb_0.27O_x/SiO₂, Ce_0.6Zr_0.4O_x/SiO₂, Ce_0.73Tb_0.27O_x/La₂O₃-Al₂O₃ and Ce_0.6Zr_0.4O_x/La₂O₃-Al₂O₃ was studied using the reduction of NO by CO. The catalysts were characterized by X-ray fluorescence, surface area, X-ray diffraction, temperature-programmed reduction, CO chemisorption and oxygen storage capacity. Temperature-programmed reduction results indicated that Tb or Zr incorporation improves the reducibility and oxygen storage capacity. CO chemisorption data suggested the presence of large PdO particles due to the low CO/Pd ratio. No significant differences were obtained in light off temperatures (T_{Light off}) for all Pd catalysts and the most active was 1.5%Pd/Ce_0.6Zr_0.4O_x/SiO₂.