The catalytic activities of the supported PdO catalysts were found to be dependenton the kind of the support as follows: CeO2>ZrO2>TiO2>Al2O3>SnO2>ZSM-5>SiO2.The reduction state of PdO in the catalys...The catalytic activities of the supported PdO catalysts were found to be dependenton the kind of the support as follows: CeO2>ZrO2>TiO2>Al2O3>SnO2>ZSM-5>SiO2.The reduction state of PdO in the catalyst played an important role in the oxidation activityof the catalyst. PdO/CeO2 was inferior to PdO/Al2O3 in heat-stability, but its activity for COoxidation was higher than PdO/Al2O3, after it had been calcinated at 1200 ℃ for 4 h.展开更多
The adsorption of NO on alumina supported Pd catalysts and the effect of adding Li 2O on NO adsorption have been investigated by using TPD MS method. Experimental results certify the existence of three types of surfac...The adsorption of NO on alumina supported Pd catalysts and the effect of adding Li 2O on NO adsorption have been investigated by using TPD MS method. Experimental results certify the existence of three types of surface species. The adsorptive dissociation of NO gives a relatively inactive intermediate N 2O. Its desorption amount is larger on Al 2O 3 and Pd/Al 2O 3 Li 2O than that on Pd/Al 2O 3. The adsorption intensity of N 2O is the strongest on Pd/Al 2O 3 Li 2O. The experiments of competitive adsorption of O 2 and NO reveal that the presence of O 2 has two effects: (1) the O atom sticks to the Pd site on the surface and inhibits the adsorption of NO, as well as the decomposition of NO; (2) O 2 can react with NO to form nitrite or nitrate species which can adsorb strongly on the surface. The relative efficiency of the two effects differs with temperature, and this can be applied to explain some phenomena in the adsorption of NO, and the selective catalytic reduction of NO as well.展开更多
文摘The catalytic activities of the supported PdO catalysts were found to be dependenton the kind of the support as follows: CeO2>ZrO2>TiO2>Al2O3>SnO2>ZSM-5>SiO2.The reduction state of PdO in the catalyst played an important role in the oxidation activityof the catalyst. PdO/CeO2 was inferior to PdO/Al2O3 in heat-stability, but its activity for COoxidation was higher than PdO/Al2O3, after it had been calcinated at 1200 ℃ for 4 h.
文摘The adsorption of NO on alumina supported Pd catalysts and the effect of adding Li 2O on NO adsorption have been investigated by using TPD MS method. Experimental results certify the existence of three types of surface species. The adsorptive dissociation of NO gives a relatively inactive intermediate N 2O. Its desorption amount is larger on Al 2O 3 and Pd/Al 2O 3 Li 2O than that on Pd/Al 2O 3. The adsorption intensity of N 2O is the strongest on Pd/Al 2O 3 Li 2O. The experiments of competitive adsorption of O 2 and NO reveal that the presence of O 2 has two effects: (1) the O atom sticks to the Pd site on the surface and inhibits the adsorption of NO, as well as the decomposition of NO; (2) O 2 can react with NO to form nitrite or nitrate species which can adsorb strongly on the surface. The relative efficiency of the two effects differs with temperature, and this can be applied to explain some phenomena in the adsorption of NO, and the selective catalytic reduction of NO as well.
