Abstract
Supported noble metal catalysts, ubiquitous in chemical technology, often undergo dynamic transformations between reduced and oxidized states—which influence the metal nuclearities, oxidation states, and catalytic properties. In this investigation, we report the results of in situ X-ray absorption spectroscopy, scanning transmission electron microscopy, and other physical characterization techniques, bolstered by density functional theory, to elucidate the structural transformations of a set of MgO-supported palladium catalysts under oxidative treatment conditions. As the calcination temperature increased, the as-synthesized supported metallic palladium nanoparticles underwent oxidation to form palladium oxides (at approximately 400 °C), which, at approximately 500 °C, were oxidatively fragmented to form mixtures of atomically dispersed palladium cations. The data indicate two distinct types of atomically dispersed species: palladium cations located at MgO steps and those embedded in the first subsurface layer of MgO. The former exhibit significantly higher (>500 times) catalytic activity for ethylene hydrogenation than the latter. The results pave the way for designing highly active and stable supported palladium hydrogenation catalysts with optimized metal utilization.
| Original language | English |
|---|---|
| Pages (from-to) | 6454-6464 |
| Number of pages | 11 |
| Journal | Chemical Science |
| Volume | 15 |
| Issue number | 17 |
| DOIs | |
| State | Published - Apr 4 2024 |
Funding
Y. C. and B. C. G. were supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) grant DE-FG02-04ER15513. Y. Z. and H. W. acknowledge the support from the U.S. National Science Foundation (DMR-2016453) for microscopy work at Purdue University. B. Y. was supported by the U.S. Office of Naval Research N00014-22-1-2160 and N00014-20-1-2043. The Stanford Synchrotron Radiation Lightsource (SSRL) of SLAC National Accelerator Laboratory is supported by BES under Contract No. DE-AC02-76SF00515. Co-ACCESS, part of the SUNCAT Center for Interface Science and Catalysis, is supported by DOE BES Chemical Sciences, Geosciences, and Biosciences Division. C. X. K. and A. R. K. were supported by DOE BES grant DE-SC0020320. R. R. acknowledges DOE BES DE-SC0020320 for the mechanistic investigation and Co-ACCESS for the QuantEXAFS analysis. Z. H. was supported by DOE BES, Chemical Sciences, Geosciences, and Biosciences Division. Electron microscopy was performed at the Oak Ridge National Laboratory Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility (M. C.). The DFT calculations were performed using the resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231.