Computational Study of CO2 Methanation on Ru/CeO2 Model Surfaces: On the Impact of Ru Doping in CeO2,ACS Catalysis

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Computational Study of CO2 Methanation on Ru/CeO2 Model Surfaces: On the Impact of Ru Doping in CeO2
ACS Catalysis ( IF 11.3 ) Pub Date : 2023-11-09 , DOI: 10.1021/acscatal.3c03742
Lulu Chen ₁ , Ivo A. W. Filot ₁ , Emiel J. M. Hensen ₁

Affiliation

The Sabatier reaction (CO₂ + H₂ → CH₄ + H₂O) can contribute to renewable energy storage by converting green H₂ with waste CO₂ into CH₄. Highly dispersed Ru on CeO₂ represents an active catalyst for the CO₂ methanation. Here, we investigated the support effect by considering a single atom of Ru and a small Ru cluster on CeO₂ (Ru₆/CeO₂). The influence of doping CeO₂ with Ru was investigated as well (Ru₆/RuCe_x–1O_2x–1). Density functional theory was used to compute the reaction energy diagrams. A single Ru atom on CeO₂ can only break one of the C–O bonds in adsorbed CO₂, making it only active in the reverse water–gas shift reaction. In contrast, Ru₆ clusters on stoichiometric and Ru-doped CeO₂ are active methanation catalysts. CO is the main reaction intermediate formed via a COOH surface intermediate. Compared to an extended Ru(11–21) surface containing step-edge sites where direct C–O bond dissociation is facile, C–O dissociation proceeds via H-assisted pathways (CO → HCO → CH) on Ru₆/CeO₂ and Ru₆/RuCe_x–1O_2x–1. A higher CO₂ methanation rate is predicted for Ru₆/RuCe_x–1O_2x–1. Electronic structure analysis clarifies that the lower activation energy for HCO dissociation on Ru₆/RuCe_x–1O_2x–1 is caused by stronger electron–electron repulsion due to its closer proximity to Ru. Strong H₂ adsorption on small Ru clusters explains the higher CO₂ methanation activity of Ru clusters on CeO₂ compared to a Ru step-edge surface, representative of Ru nanoparticles, where the H coverage is low due to stronger competition with adsorbed CO.

中文翻译：

Ru/CeO2 模型表面 CO2 甲烷化的计算研究：CeO2 中 Ru 掺杂的影响

Sabatier反应（CO ₂ + H ₂ → CH ₄ + H _{2 O）可以通过将绿色H}₂与废弃CO ₂转化为CH ₄来促进可再生能源存储。CeO _{2上高度分散的Ru代表了CO}₂甲烷化的活性催化剂。在这里，我们通过考虑 Ru 的单个原子和 CeO ₂上的小 Ru 簇（Ru ₆ /CeO ₂）来研究支撑效应。还研究了用 Ru掺杂 CeO ₂的影响(Ru ₆ /RuCe _{x –1} O _{2 x –1} )。密度泛函理论用于计算反应能量图。_{CeO 2}上的单个Ru原子只能破坏吸附CO ₂中的一个C-O键，使其仅在逆水煤气变换反应中活跃。相反，化学计量和Ru掺杂的CeO _2上的Ru₆簇是活性甲烷化催化剂。CO是通过COOH表面中间体形成的主要反应中间体。与包含易于直接 C-O 键解离的阶梯边缘位点的扩展 Ru(11-21) 表面相比，Ru ₆ /CeO ₂上的 C-O 解离通过 H 辅助途径 (CO → HCO → CH) 进行，并且Ru ₆ /RuCe _x_–1 O ₂_x_–1。_{Ru 6} /RuCe _x_–1 O ₂_x_–1预计具有更高的CO ₂甲烷化率。_{电子结构分析表明，Ru 6} /RuCe _x_–1 O ₂_x_–1上 HCO 解离的较低活化能是由于其更接近 Ru 导致的更强的电子-电子排斥力造成的。小Ru簇上的强H ₂吸附解释了与Ru阶梯边缘表面（代表Ru纳米颗粒）相比， CeO ₂上的Ru簇具有更高的CO ₂甲烷化活性，其中由于与吸附的CO更强的竞争，H覆盖率较低。

更新日期：2023-11-09

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