One-step synthesis of nanostructured Pd-doped mixed oxides MOx-CeO2 (M = Mn, Fe, Co, Ni, Cu) for efficient CO and C3H8 total oxidation
One-step synthesis of nanostructured Pd-doped mixed oxides MOx-CeO2 (M = Mn, Fe, Co, Ni, Cu) for efficient CO and C3H8 total oxidation
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一步合成纳米结构 Pd 掺杂混合氧化物 MOx-CeO2（M = Mn、Fe、Co、Ni、Cu），用于高效 CO 和 C3H8 完全氧化
DOI：
10.1016/j.apcatb.2008.08.017
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发表时间：
2009-03-16
影响因子：
22.1
通讯作者：
Zhang, Tian-Yong
中科院分区：
文献类型：
--
作者：
Luo, Jin-Yong;Meng, Ming;Zhang, Tian-Yong
采用表面活性剂辅助共沉淀法一步合成了一系列Pd掺杂的纳米复合氧化物MOx-CeO 2（M = Mn，Fe，Co，Ni，Cu），具有均匀的介孔结构和超过115 m2 g-1的大比表面积。以CO和C3 H8的完全氧化反应为模型反应考察了它们的催化性能。结果表明，即使是微量的暴露的Pd和3d-过渡金属氧化物之间存在的协同作用CO氧化，而这种效果是不存在的C3 H8氧化。原位漫反射红外光谱（DRIFTS）研究表明，CO氧化的协同机理是Pd和MOx之间的相互作用离子辅助生成的活性氧物种，该活性氧物种容易与CO反应，生成双齿碳酸盐（1587和1285 cm（-1））作为中间产物.此外，结构表征结果表明，CeO 2和Mn 2 O3或Fe 2 O3之间形成固溶体，导致Pd和MOx之间非常强的相互作用，以及大大提高CO氧化。与不含Pd的催化剂相比，掺杂Pd的Mn和含Fe催化剂的起燃温度分别降低了70和100 ℃以上。特别地，即使在室温下，在Pd掺杂的含Mn催化剂上也可以实现高达80%的CO转化率。而C_3H_8的氧化反应主要是C-H键的活化，而不是氧的活化。催化剂的C-H键活化能力在很大程度上取决于M阳离子的d电子构型。随着d电子数的增加，出现了“双峰”现象。(C)2008 Elsevier B. V.保留所有权利。
A series of nanostructured Pd-doped mixed oxides MOx-CeO2 (M = Mn, Fe, Co, Ni, Cu), with uniform mesoporous structure and large surface area exceeding 115 m(2) g(-1), were synthesized in one step by a surfactant-assisted co-precipitation. Their catalytic performance was investigated using total oxidation of CO and C3H8 as the model reactions. The results show that, a synergism exists between even trace amounts of exposed Pd and 3d-transition metal oxides for CO oxidation, whereas such an effect is absent for C3H8 oxidation. in situ diffuse reflectance infrared spectroscopy (DRIFTS) study reveals that the synergistic essential for CO oxidation should be the interact ion-assisted generation of active oxygen species between Pd and MOx, which react readily with CO, forming bidentate carbonate (1587 and 1285 cm(-1)) as intermediates. Moreover, structural characterization results indicate that a solid solution is formed between CeO2 and Mn2O3 or Fe2O3, resulting in the very strong interaction between Pd and MOx, as well as the greatly improved CO oxidation. The light-off temperatures for Pd-doped Mn and Fe-containing catalysts, as compared with the Pd-free catalysts, are decreased by more than 70 and 100 degrees C, respectively. In particular, a CO conversion as high as 80% can be achieved even at room temperature on Pd-doped Mn-containing catalyst. While for C3H8 oxidation, the C-H bond activation, but not the oxygen activation, plays a crucial role. The C-H bond activation ability of the catalysts is largely determined by the d-electron configurations of the M cations. A 'double-peak' phenomenon can be derived with the increase of d-electron number. (C) 2008 Elsevier B.V. All rights reserved.