A new monolithic Pt-Pd-Rh motorcycle exhaust catalyst to meet future emission standards

Abstract

A new composite oxide material as support, CeO2-ZrO2-La2O3-PrO2-Al2O3, was synthesized by a co-precipitation method. Pd-Rh, Pt-Rh, and Pt-Pd-Rh supported on monolithic carrier catalysts were obtained by an impregnation route. The textural, structural, and reductive properties of the catalysts were characterized by N2 adsorption-desorption, temperature-programmed reduction, oxygen storage capacity measurements, and X-ray diffraction. The air-fuel-ratio (A/F), space velocity (SV), and temperature characteristics of the fresh and aged catalysts were investigated on a systematic basis. The results showed that among the three catalysts, Pt-Pd-Rh displayed the best performance. For an SV of 40000 h−1 in the case of fresh Pt-Pd-Rh, the light-off temperatures (T50) for C3H8, CO, and NO were 239, 187, and 191 °C, respectively, with corresponding ΔT (T90–T50) values of 21, 3, and 3 °C, respectively. After aging, the T50 for C3H8, CO, and NO were 298, 203, and 223 °C, respectively, and the ΔT values were 22, 5, and 13 °C, respectively. Moreover, the window widths for the A/F in the case of fresh and aged Pt-Pd-Rh catalysts were wide. Overall, the excellent performance for the Pt-Pd-Rh catalyst makes it suitable as a motorcycle exhaust catalyst, which can meet future emission standards.