Catalytic combustion of toluene over Pd-based monolithic catalysts with a novel washcoat Ce 0.8Zr 0.15La 0.05O δ

Abstract

Two novel washcoats Ce 0.8Zr 0.15La 0.05O δ and Ce 0.8Zr 0.2O 2 was prepared by an impregnation method, which acted as a host for the active Pd component to prepare Pd/Ce 0.8Zr 0.15La 0.05O δ/substrate and Pd/Ce 0.8Zr 0.2O 2/substrate monolithic catalysts for toluene combustion. The washcoats was characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauner-Emmett-Teller (BET), and H 2-temperature-programmed reduction (H 2-TPR). The result indicated that both the washcoats had strong vibration-shock resistance according to ultrasonic test. Doping La 3+ into CeO 2-ZrO 2 solid solution could generate more oxygen vacancies, and could inhibit the sinter of CeO 2-ZrO 2 solid solution when calcined at high temperatures (800, 900 and 1000 °C). The washcoat Ce 0.8Zr 0.15La 0.05O δ had much better redox properties. The reductive temperature of Ce 4+ species shifted to low temperature by 60 °C when the washcoats calcined at high temperatures (800, 900 and 1000 °C). The Pd/Ce 0.8Zr 0.15La 0.05O δ/substrate monolithic catalyst calcination at 500 °C had the best catalytic activity and the 95% toluene conversion at a temperature as low as 190 °C. When calcined at low temperature (500 and 700 °C), the catalytic activity has little improvement, however, when calcined at high temperature, the catalytic activity of Pd/Ce 0.8Zr 0.15La 0.05O δ/substrate monolithic catalysts had significant improvement. As catalyst washcoat, the Ce 0.8Zr 0.15La 0.05O δ had better thermal stability than the washcoat Ce 0.8Zr 0.2O 2, the developed Pd/Ce 0.8Zr 0.15La 0.05O δ/substrate monolithic catalyst in this work was promising for eliminating Volatile organic compounds.