One-electron reducibility of isolated copper oxide on alumina for selective NO-CO reaction
One-electron reducibility of isolated copper oxide on alumina for selective NO-CO reaction
复制标题
DOI：
10.1016/j.apcatb.2005.12.011
复制
发表时间：
2006-05
影响因子：
22.1
通讯作者：
Fumiaki Amano;Sosuke Suzuki;Takashi Yamamoto;Tsunehiro Tanaka
中科院分区：
文献类型：
--
作者：
Fumiaki Amano;Sosuke Suzuki;Takashi Yamamoto;Tsunehiro Tanaka
对低负载量（0.5wt%铜）的负载型氧化铜催化剂进行了H2-TPR（程序升温还原）研究。在各种载体材料（γ-Al_2O_3、TiO_2、ZrO_2、SiO_2、ZSM-5）中，氧化铝负载的氧化铜在H_2存在下表现出单电子还原行为。通过X射线吸收光谱（XANES和EXAFS）确定了四方畸变八面体对称中的孤立Cu 2+物种还原成低配位Cu+离子。在773 K的H_2还原条件下，γ-Al_2O_3表面的孤立Cu ~+离子不能被进一步还原成金属Cu ~（0+）态。在573 K下，分散度较低的负载型氧化铜易于被H2还原为Cu 0金属颗粒，而与载体材料的种类无关。结果表明，在有氧存在下，γ-Al 2 O3上孤立的氧化铜物种的单电子氧化还原行为促进了CO催化还原NO的反应，其机理是原子分散态Cu ~（2+）与Cu ~（++）之间的氧化还原型机理.
The H2-TPR (temperature-programmed reduction) study was performed for supported copper oxide catalysts with low loading (0.5wt% as copper). Among the various kinds of support materials (γ-Al2O3, TiO2, ZrO2, SiO2, ZSM-5), alumina-supported copper oxide indicated a one-electron reduction behavior of Cu2+into Cu+ions in the presence of H2. The reduction of the isolated Cu2+species in a tetragonally distorted octahedral symmetry into the low coordinated Cu+ions was identified by means of X-ray absorption spectroscopy (XANES and EXAFS). The isolated Cu+ions hosted by γ-Al2O3surface were prevented from further reduction into metallic Cu0state under reducing condition with H2at 773K. Less dispersed supported copper oxide species were easily reduced to Cu0metal particles with H2at 573K regardless of the kinds of support materials. It is suggested that the one-electron redox behavior of the isolated copper oxide species over γ-Al2O3promotes the catalytic reduction of NO with CO in the presence of oxygen on the basis of redox-type mechanism between Cu2+and Cu+in atomically dispersed state.