Decoding the Reactivity Enhancement of Ln2Ce2O7 Compounds (Ln = Yb, Y, Tb, and Gd) for Soot Combustion: The Remarkable Contribution of Variable Valence A-Sites

作者：Shijing Zhang, Junwei Xu, Zekai Xu, Yuting Li, Ping Wang, Lu Xiao, Jiating Shen, Xiuzhong Fang, Xianglan Xu, Xiang Wang · 发表于：Inorganic Chemistry · 年份：2024 · DOI：10.1021/acs.inorgchem.4c00142 · 被引用次数：12 · 研究领域：Catalytic Processes in Materials Science、Luminescence Properties of Advanced Materials、Catalysis and Oxidation Reactions

The impact of variable valence A-sites on the redox property and reactivity of Ln 2 Ce 2 O 7 compounds in soot particulate combustion has been investigated. It was observed that Yb 2 Ce 2 O 7, Y 2 Ce 2 O 7, and Gd 2 Ce 2 O 7 formed a rare earth C-type phase, while Tb 2 Ce 2 O 7 formed a solid solution phase. Both Tb 2 Ce 2 O 7 and Yb 2 Ce 2 O 7 possess dual valence state A-sites, resulting in significantly more surface vacancies. Additionally, the advantageous solid solution phase structure of Tb 2 Ce 2 O 7 leads to even more surface vacancies than Yb 2 Ce 2 O 7, which is crucial to generate active oxygen sites. Moreover, the introduction of NO into the reaction feed enhances combustion activity by producing active surface monodentate nitrates. A catalyst with higher numbers of surface vacancies exhibits improved NO oxidation ability and better NO 2 utilization efficiency. Consequently, the Tb 2 Ce 2 O 7 compound demonstrates not only the best soot combustion activity, but also an optimal NO x -assistance effect. Therefore, it is concluded that variable valence A-site is the intrinsic factor to improve the reactivity of Ln 2 Ce 2 O 7 catalysts.