Catalytic combustion of toluene over Pd-based monolithic catalysts with a novel washcoat Ce0.8Zr0.15La0.05Oδ

Two novel washcoats Ce0.8Zr0.15La0.05O delta and Ce0.8Zr0.2O2 was prepared by an impregnation method, which acted as a host for the active Pd component to prepare Pd/Ce0.8Zr0.15La0.05O delta/substrate and Pd/Ce0.8Zr0.2O2/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 La3+ into CeO2-ZrO2 solid solution could generate more oxygen vacancies, and could inhibit the sinter of CeO2-ZrO2 solid solution when calcined at high temperatures (800, 900 and 1000 degrees C). The washcoat Ce0.8Zr0.15La0.05O delta had much better redox properties. The reductive temperature of Ce4+ species shifted to low temperature by 60 degrees C when the washcoats calcined at high temperatures (800, 900 and 1000 degrees C). The Pd/Ce0.8Zr0.15La0.05O delta/substrate monolithic catalyst calcination at 500 degrees C had the best catalytic activity and the 95% toluene conversion at a temperature as low as 190 degrees C. When calcined at low temperature (500 and 700 degrees C), the catalytic activity has little improvement, however, when calcined at high temperature, the catalytic activity of Pd/Ce0.8Zr0.15La0.05O delta/substrate monolithic catalysts had significant improvement. As catalyst washcoat, the Ce0.8Zr0.15La0.05O delta had better thermal stability than the washcoat Ce0.8Zr0.2O2, the developed Pd/Ce0.8Zr0.15La0.05O delta/substrate monolithic catalyst in this work was promising for eliminating Volatile organic compounds.