RT journal article
T1 Role of Interfacial Hydrogen in Ethylene Hydrogenation on Graphite-Supported Ag, Au, and Cu Catalysts
A1 Wicht, Thomas
A1 Genest, Alexander
A1 Chinchilla Reyes, Lidia Esther
A1 Haunold, Thomas
A1 Steiger-Thirsfeld, Andreas
A1 Calvino Gámez, José Juan
A1 Rupprechter, Günther
A2 Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
K1 carbon support
K1 density functional theory
K1 electron microscopy
K1 ethylene hydrogenation
K1 photoelectron spectroscopy
AB A combined surface science/microreactor approach was applied to examine interface effects in ethylene hydrogenation on carbon-supported Ag, Au, and Cu nanoparticle catalysts. Turnover frequencies (TOFs) were substantially higher for supported catalysts than for (unsupported) polycrystalline metal foils, especially for Ag. Spark ablation of the corresponding metals on highly oriented pyrolytic graphite (HOPG) and carbon-coated grids yielded nanoparticles of around 3 nm size that were well-suited for characterization by X-ray photoelectron spectroscopy (XPS), high-resolution (scanning) transmission electron microscopy (HRTEM/STEM), and energy dispersive X-ray spectroscopy (EDX). Polycrystalline metal foils characterized by scanning electron microscopy (SEM), EDX, electron backscatter diffraction (EBSD), XPS, and low-energy ion scattering (LEIS) served as unsupported references. Employing a UHV-compatible flow microreactor and gas chromatography (GC) allowed us to determine the catalytic performance of the model catalysts in ethylene hydrogenation up to 200 °C under atmospheric pressure. Compared to the pure metal foils, the HOPG-supported metal nanoparticles exhibited not only strongly increased activity but also higher stability (slower deactivation) and differing reaction orders. For the most active Ag catalysts, DFT calculations were carried out to determine the adsorption energies of the reacting species on single-crystal surfaces as well as on carbon-supported and unsupported Ag nanoparticles. Adsorption of molecular hydrogen was very weak on all unsupported Ag surfaces, resulting in hydrocarbon-“poisoned” surfaces. However, when a carbon support was present, the adsorption strength of H2 on Ag nanoparticles increased on average by −0.5 eV, driven by changes in Ag-Ag distances near the metal-carbon three-phase boundary (whereas subsurface carbon lowers hydrogen bonding). On Cu particles, the interface effect was calculated to be somewhat weaker than for Ag particles. H2/D2 scrambling experiments on Ag catalysts then corroborated a facilitated hydrogen activation for carbon-supported metals. Thus, the carbon support effect is attributed to an improved hydrogen availability at the metal-carbon interface, controlling performance.
PB American Chemical Society
SN 2155-5435
YR 2024
FD 2024
LK http://hdl.handle.net/10498/35959
UL http://hdl.handle.net/10498/35959
LA eng
DS Repositorio Institucional de la Universidad de Cádiz
RD 12-nov-2026