Low-Temperature CO 2 Methanation over CeO 2 -Supported Ru Single Atoms, Nanoclusters, and Nanoparticles Competitively Tuned by Strong Metal–Support Interactions and H-Spillover Effect

作者：Yu Guo, Sheng Mei, Kun Yuan, De‐Jiu Wang, Haichao Liu, Chun‐Hua Yan, Ya‐Wen Zhang · 发表于：ACS Catalysis · 年份：2018 · DOI：10.1021/acscatal.7b04469 · 被引用次数：1022 · 研究领域：Catalysts for Methane Reforming、Catalytic Processes in Materials Science、Carbon dioxide utilization in catalysis

CO 2 hydrogenation for the acquisition of value-added chemicals is an economical means to deal with the CO 2 -relevant environmental problems, among which CO 2 reduction to CH 4 is an excellent model reaction for investigating the initial steps of CO 2 hydrogenation. For the supported catalysts commonly used in such reactions, the tailoring of the interfacial effect between metal centers and supporting materials so as to obtain superior low-temperature CO 2 methanation performance is a significant but challenging subject. In this work, we altered the size regimes of the Ru deposits in Ru/CeO 2 assemblies and uncovered the competitive relationship between the strong metal–support interactions (SMSI) and the H-spillover effect in determining the methanation activities by some ex situ and in situ spectroscopic techniques coupled with density functional theory (DFT) calculations. For CeO 2 nanowire supported single Ru atoms, Ru nanoclusters (ca. 1.2 nm in size), and large Ru nanoparticles (ca. 4.0 nm in size), the nanoclusters show the most outstanding low-temperature CO 2 methanation activity and 98–100% selectivity, with a turnover frequency (TOF) of 7.41 × 10 –3 s –1 at 190 °C. The negative CO 2 reaction order decreases their absolute values from single atoms to nanoclusters and turns positive in nanoparticles, while the positive H 2 reaction order follows the reverse tendency. In situ DRIFTS measurements demonstrate that the dominant reaction pathway is the CO route, in which...