LaO_(x)(OH)_(y) supported platinum catalysts for CO oxidation:Deactivation by formation of lanthanum carbonate  

作　　者：Luozhen Jiang Junxiang Chen Rui Si 

机构地区：[1]Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201204,China [2]Shanghai Synchrotron Radiation Facility,Zhangjiang Laboratory,Shanghai 201204,China [3]Division of China,TILON Group Technology Limited,Shanghai 200090,China [4]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Journal of Rare Earths》2021年第3期297-304,I0003,共9页稀土学报（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(21773288);National Key Basic Research Program of China(2017YFA0403402)。

摘　　要：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 lantha num oxide or hydroxide supports(LaO_(x)(OH)_(y)),and deposited platinum(Pt) with 0.5 at% via an impregnation approach to synthesize Pt/LaO_(x)(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 LaO_(x)(OH)_(y).Furthermore,the as-formed lanthanum carbonate(La_(2)O_(2)CO_(3)) during the exposure to ambient circumstances or in the reaction atmosphere of CO+O_(2),severely impair the reactivity of Pt/LaO_(x)(OH)_(y).On the basis of the obtained experimental results,we have drawn a conclusion that the oxidized P_(t)O_(x) atoms or PtxOy clusters are the active species for CO oxidation,while the formation of lanthanum carbonate is the origin of deactivation on reactivity.

关 键 词：Platinum catalyst Lanthanum oxide Lanthanum hydroxide CO oxidation Structure-activity relationship Rare earths 

分 类 号：O643.36[理学—物理化学]