LaOx(OH)y supported platinum catalysts for CO oxidation: Deactivation by formation of lanthanum carbonate
LaOx(OH)y supported platinum catalysts for CO oxidation: Deactivation by formation of lanthanum carbonate
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DOI：
10.1016/j.jre.2020.02.016
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发表时间：
2021-02-24
影响因子：
4.9
通讯作者：
Si, Rui
中科院分区：
文献类型：
--
作者：
Jiang, Luozhen;Chen, Junxiang;Si, Rui
铂系催化剂具有活性高、稳定性好等优点，在CO氧化反应中得到了广泛的研究。在这项工作中，我们制备了三种不同的氧化镧或氢氧化镧载体（LaOx（OH）（y）），并通过浸渍方法沉积了0.5at%的铂（Pt）以合成Pt/LaOx（OH）（y）催化剂。然而，我们发现这些催化剂对于CO氧化反应表现出较差的稳定性。采用X射线粉末衍射（XRD）、X射线吸收精细结构（XAFS）、透射电子显微镜（TEM）、一氧化碳程序升温还原（CO-TPR）和热重分析（TGA）等多种技术对新鲜样品和使用过的样品进行了综合表征，证明氧化的铂原子或团簇不含任何Pt-Pt金属键，在LaOx（OH）（y）的表面上高度分散。此外，在暴露于环境环境或在CO + O-2的反应气氛中期间形成的碳酸镧（La 2 O2 CO 3）严重损害Pt/LaOx（OH）（y）的反应性。根据实验结果，我们得出结论，氧化的PtOx原子或PtxOy团簇是CO氧化的活性物种，而碳酸镧的形成是CO氧化反应性失活的根源。(C)2020中国稀土学会Elsevier B. V.出版，保留所有权利。
Platinum catalyst for CO oxidation has been studied for decades, due to its high activity and good stability. In this work, we prepared three different lanthanum oxide or hydroxide supports (LaOx(OH)(y)), and deposited platinum (Pt) with 0.5 at% via an impregnation approach to synthesize Pt/LaOx(OH)(y) catalysts. However, we find that these catalysts perform a poor stability for the CO oxidation reaction. The fresh and used samples were comprehensively characterized by multiple techniques including power X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), transmission electron microscopy (TEM), temperature-programmed reduction by carbon monoxide (CO-TPR) and thermogravimetric analysis (TGA), to demonstrate that the oxidized platinum atoms or clusters, without any component of Pt-Pt metallic bond, are highly dispersed on the surface of LaOx(OH)(y). Furthermore, the as-formed lanthanum carbonate (La2O2CO3) during the exposure to ambient circumstances or in the reaction atmosphere of CO + O-2, severely impair the reactivity of Pt/LaOx(OH)(y). On the basis of the obtained experimental results, we have drawn a conclusion that the oxidized PtOx atoms or PtxOy clusters are the active species for CO oxidation, while the formation of lanthanum carbonate is the origin of deactivation on reactivity. (C) 2020 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.