Carbon oxidation with Ag/ceria prepared by self-dispersion of Ag powder into nano-particles
Carbon oxidation with Ag/ceria prepared by self-dispersion of Ag powder into nano-particles
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DOI：
10.1016/j.cattod.2011.03.053
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发表时间：
2011-10
期刊：
影响因子：
5.3
通讯作者：
K. Shimizu;H. Kawachi;S. Komai;Kaname Yoshida;Y. Sasaki;A. Satsuma
中科院分区：
文献类型：
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作者：
K. Shimizu;H. Kawachi;S. Komai;Kaname Yoshida;Y. Sasaki;A. Satsuma
本文报道了一种独特的制备Ag/CeO 2碳氧化催化剂的新方法。Ag金属粉末和CeO 2的物理混合物在500°C下煅烧导致Ag在CeO 2上自分散成纳米颗粒。从TEM图像可以看出，煅烧前银粉中Ag颗粒的平均粒径在66 nm左右，而煅烧后Ag颗粒的粒径变小，在8 nm左右，且分布很窄。CeO 2表面的氧空位在Ag的自分散中起着重要的作用。该催化剂对碳烟的氧化活性可与浸渍法制备的Ag/CeO 2相媲美。在与Cu、Au和Pt的物理混合物中，没有观察到CeO 2的促进作用。还检查了Ag和各种金属氧化物载体的机械混合物。在CeO 2、SnO 2、ZrO 2、ZnO、TiO 2和Nb 2 O 5中加入Ag后，碳的氧化温度明显降低，而在Co 3 O 4、CaO、La 2 O3、NiO、SiO2、Al 2 O3和MgO中加入Ag后，碳的氧化温度没有明显降低。
This study reports a unique and novel method of preparation of Ag/CeO2catalyst for carbon oxidation. A calcination of physical mixture of Ag metal powder and CeO2at 500°C results in self-dispersion of Ag into nano-particles on CeO2. From TEM images, the average diameter of Ag particles in Ag power before calcination was around 66nm, while the particle size of Ag became smaller around 8nm with very narrow distribution. Oxygen vacancy on CeO2surface is suggested to play an important role in the self-dispersion of Ag. The obtained catalyst showed high activity for soot oxidation comparable to Ag/CeO2prepared by impregnation method. The promotion effect of CeO2was not observed in physical mixtures with Cu, Au and Pt. Mechanical mixtures of Ag and various metal oxide supports were also examined. The addition of Ag to CeO2, SnO2, ZrO2, ZnO, TiO2, and Nb2O5significantly lowered the temperature of carbon oxidation than those of supports, while that to Co3O4, CaO, La2O3, NiO, SiO2, Al2O3and MgO did not.