Lushchikova Olga V, Szalay Máté, Tahmasbi Hossein, Juurlink Ludo B F, Meyer Jörg, Höltzl Tibor, Bakker Joost M
Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands.
MTA-BME Computation Driven Chemistry Research Group, Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Muegyetem rkp. 3, Budapest 1111, Hungary.
Phys Chem Chem Phys. 2021 Dec 8;23(47):26661-26673. doi: 10.1039/d1cp03119h.
To understand elementary reaction steps in the hydrogenation of CO over copper-based catalysts, we experimentally study the adsorption of CO and H onto cationic Cu clusters. For this, we react Cu clusters formed by laser ablation with a mixture of H and CO in a flow tube-type reaction channel and characterize the products formed by IR multiple-photon dissociation spectroscopy employing the IR free-electron laser FELICE. We analyze the spectra by comparing them to literature spectra of Cu clusters reacted with H and with new spectra of Cu clusters reacted with CO. The latter indicate that CO is physisorbed in an end-on configuration when reacted with the clusters alone. Although the spectra for the co-adsorption products evidence H dissociation, no signs for CO activation or reduction are observed. This lack of reactivity for CO is rationalized by density functional theory calculations, which indicate that CO dissociation is hindered by a large reaction barrier. CO reduction to formate should energetically be possible, but the lack of formate observation is attributed to kinetic hindering.
为了理解在铜基催化剂上CO加氢的基元反应步骤，我们通过实验研究了CO和H在阳离子铜簇上的吸附。为此，我们使激光烧蚀形成的铜簇与H和CO的混合物在流动管型反应通道中反应，并使用红外自由电子激光FELICE通过红外多光子解离光谱对形成的产物进行表征。我们通过将光谱与H反应的铜簇的文献光谱以及CO反应的铜簇的新光谱进行比较来分析光谱。后者表明，当单独与簇反应时，CO以端对端构型物理吸附。尽管共吸附产物的光谱证明了H的解离，但未观察到CO活化或还原的迹象。密度泛函理论计算解释了CO这种缺乏反应性的现象，计算表明CO解离受到较大反应势垒的阻碍。从能量角度来看，CO还原形成甲酸盐是可能的，但未观察到甲酸盐是由于动力学阻碍。
