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

• 作者: Luozhen Jiang Junxiang Chen Rui Si
• 来源期刊: 稀土学报（英文版）
• 年，卷（期）: 2021,（3）
• 所属期刊栏目: RARE EARTH CATALYSIS
• 页码范围: 297-304
• 页数: 8页
• 语种: 英文

摘要

Platinum catalyst for CO oxidation has been studied for decades, due to its high activity and good sta-bility. 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 at-mosphere of CO + O2, 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.