N2O is a powerful greenhouse gas and plays an important role in destructing the ozone layer. This present work investigated the effects of Pd doping on N2O formation over Pt/BaO/Al2O3 catalyst. Three types of catalyst...N2O is a powerful greenhouse gas and plays an important role in destructing the ozone layer. This present work investigated the effects of Pd doping on N2O formation over Pt/BaO/Al2O3 catalyst. Three types of catalysts, Pt/BaO/Al2O3, Pt/Pd mechanical mixing catalyst （Pt/BaO/Al203 ＋ Pd/Al2O3） and Pt-Pd co-impregnation catalyst （Pt-Pd/BaO/Al2O3） were prepared by incipient wetness imoreenation method. These catalysts were first evaluated in NSR activity tests using H2/CO as reductants and then carefully characterized by BET, CO chemisorption, CO-DRIFTs and H2-TPR techniques. In addition, temperature programmed reactions of NO with H2/CO were conducted to obtain further information about NzO formation mechanism. Compared with Pt/BaO/Al2O3 （Pt/BaO/Al2O3 ＋ Pd/Al2O3） produced less N2O and more NH3 during NOx storage and reduction process, while an opposite trend was found over （Pt-Pd/BaO/Al2O3 ＋ Al2O3）. Temperature programmed reactions of NO with H2/CO results showed that Pd/Al2O3 component in （Pt/BaO/Al2O3 ＋ Pd/Al2O3） played an important role in NO reduction to NH3, and the formed NH3 could reduce NOx to N2 leading to a decrease in N2O formation. Most of N2O formed over （Pt-Pd/BaO/Al2O3 ＋ Al2O3） was originated from Pd/BaO/Al2O3 component. H2-TPR results indicated Pd-Ba interaction resulted in more difficult- to-reduce PdOx species over Pd/BaO/Al2O3, which inhibits the NO dissociation and thus drives the selectivity to N2O in NO reduction.展开更多
MAKAROV and Trontelj first reported the WO<sub>3</sub>-based low voltage varistor material doped with MnO<sub>2</sub> and Na<sub>2</sub>CO<sub>3</sub> in 1994. This mate...MAKAROV and Trontelj first reported the WO<sub>3</sub>-based low voltage varistor material doped with MnO<sub>2</sub> and Na<sub>2</sub>CO<sub>3</sub> in 1994. This material is worth further study because of its low threshold voltage （ 【 10 V/mm）. We have found that the doping of Co<sub>2</sub>O<sub>3</sub> can obviously improve the nonlinearity of WO<sub>3</sub>-MnO<sub>2</sub>-Na<sub>2</sub>CO<sub>3</sub> series with nonlinear coefficient α≈ 2,and a may be higher than 5 when the amount of Co<sub>2</sub>O<sub>3</sub> is 1% （mole percentage）. However, the nonlinear characteristic almost vanished when 0.5% Al<sub>2</sub>O<sub>3</sub> was doped into this system at room temperature, and Al<sub>2</sub>O<sub>3</sub> showed very stable展开更多
基金Acknowledgements This work was financially supported by the National Key Research and Development Program （No. 2017YFC0211002） and the National Natural Science Foundation of China （Grant No. 21476170）.
文摘N2O is a powerful greenhouse gas and plays an important role in destructing the ozone layer. This present work investigated the effects of Pd doping on N2O formation over Pt/BaO/Al2O3 catalyst. Three types of catalysts, Pt/BaO/Al2O3, Pt/Pd mechanical mixing catalyst （Pt/BaO/Al203 ＋ Pd/Al2O3） and Pt-Pd co-impregnation catalyst （Pt-Pd/BaO/Al2O3） were prepared by incipient wetness imoreenation method. These catalysts were first evaluated in NSR activity tests using H2/CO as reductants and then carefully characterized by BET, CO chemisorption, CO-DRIFTs and H2-TPR techniques. In addition, temperature programmed reactions of NO with H2/CO were conducted to obtain further information about NzO formation mechanism. Compared with Pt/BaO/Al2O3 （Pt/BaO/Al2O3 ＋ Pd/Al2O3） produced less N2O and more NH3 during NOx storage and reduction process, while an opposite trend was found over （Pt-Pd/BaO/Al2O3 ＋ Al2O3）. Temperature programmed reactions of NO with H2/CO results showed that Pd/Al2O3 component in （Pt/BaO/Al2O3 ＋ Pd/Al2O3） played an important role in NO reduction to NH3, and the formed NH3 could reduce NOx to N2 leading to a decrease in N2O formation. Most of N2O formed over （Pt-Pd/BaO/Al2O3 ＋ Al2O3） was originated from Pd/BaO/Al2O3 component. H2-TPR results indicated Pd-Ba interaction resulted in more difficult- to-reduce PdOx species over Pd/BaO/Al2O3, which inhibits the NO dissociation and thus drives the selectivity to N2O in NO reduction.
文摘MAKAROV and Trontelj first reported the WO<sub>3</sub>-based low voltage varistor material doped with MnO<sub>2</sub> and Na<sub>2</sub>CO<sub>3</sub> in 1994. This material is worth further study because of its low threshold voltage （ 【 10 V/mm）. We have found that the doping of Co<sub>2</sub>O<sub>3</sub> can obviously improve the nonlinearity of WO<sub>3</sub>-MnO<sub>2</sub>-Na<sub>2</sub>CO<sub>3</sub> series with nonlinear coefficient α≈ 2,and a may be higher than 5 when the amount of Co<sub>2</sub>O<sub>3</sub> is 1% （mole percentage）. However, the nonlinear characteristic almost vanished when 0.5% Al<sub>2</sub>O<sub>3</sub> was doped into this system at room temperature, and Al<sub>2</sub>O<sub>3</sub> showed very stable
