Catalytic combustion of toluene over Pd-based monolithic catalysts with a novel washcoat Ce_(0.8)Zr_

Two novel washcoats Ce_(0.8)Zr_(0.15)La_(0.05)O_δ and Ce_(0.5)Zr_(0.2)O_2 was prepared by an impregnation method, which acted as a host for the active Pd component to prepare Pd/Ce_(0.8)Zr_(0.15)La_(0.05)O_δ/substrate and Pd/Ce_(0.5)Zr_(0.2)O_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 (H2-TPR). The result indicated that both the washcoats had strong vibration-shock resistance accord-hag to ultrasonic test. Doping La3+ 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 ℃). The washcoat Ce_(0.8)Zr_(0.15)La_(0.05)O_δ had much better re-dox properties. The reductive temperature of Ce~(4+) species shifted to low temperature by 60℃ when the washcoats calcined at high tempera-tures (800, 900 and 1000 ℃). The Pd/Ce_(0.8)Zr_(0.15)La_(0.05)O_δ/substrate monolithic catalyst calcination at 500℃ had the best catalytic activity and the 95% toluene conversion at a temperature as low as 190℃. When calcined at low temperature (500 and 700 ℃), the catalytic activity has little improvement, however, when calcined at high temperature, the catalytic activity of Pd/Ce_(0.8)Zr_(0.15)La_(0.05)O_δ/substrate monolithic catalysts had significant improvement. As catalyst washcoat, the Ce_(0.5)Zr_(0.15)La_(0.05)O_δ had better thermal stability than the washcoat Ce_(0.8)Zr_(0.2)O_2 the de-veloped Pd/Ce_(0.8)Zr_(0.15)La_(0.05)O_δ/substrate monolithic catalyst in this work was promising for eliminating Volatile organic compounds.