Birdnest-like CuCeZr Mixed Oxides: Excellent Catalysts for Diesel Exhaust Oxidation

A series of ternary composite oxides CuCeZrOx calcined at different temperatures were prepared by a homogeneous precipitation method using urea as the precipitant. X-ray diffraction (XRD), N-2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscope (STEM), and temperature-programmed reduction (or desorption, oxidation) (TPR, TPD or TPO) measurements were utilized to investigate the influence of calcination temperatures on the physicochemical property and catalysis performance towards soot catalytic oxidation. The CCZ-350 (calcined at 350 degrees C) sample exhibits the optimized catalysis performance: temperature at the maximum rate of soot oxidation (T-50) = 407 degrees C, under test conditions of space velocity = 12000 mL/(g(catalyst).h), c(O-2) = 10vol%, c(NO) = 500x10(-6), and mass ratio of (loosely contacted) catalyst/soot = 10/1. It is believed that theabundant high-reactive adsorbed oxygen species on CCZ-350 surface contribute much to its outstanding catalysis performance. Besides, CCZ-350 with a loose-packing and porous morphology favors its sufficient contact with soot, thus further benefiting the catatlytic activity towards soot combustion. More importantly, CCZ-350 also presents good water vapor and SO2 resistence performance as well as good capability of eliminating other pollutants in diesel exhaust at low temperatures (150-400 degrees C), such as CO, C3H6 and C3H8.