Abstract
Atomically dispersed gold supported on nanoscale ZnZrOx composite oxides was prepared and investigated in this work as a catalyst for the low-temperature ethanol dehydrogenation reactions. The composite ZnZrOx support disperses gold atomically and stabilizes it against growth much better than either of the neat oxides. Sequential ethanol conversion reactions to acetaldehyde and acetone take place on the Au/ZnZrOx catalysts within well-separated temperature windows over the range of tested temperatures (30-400 °C). ZnO modulates the acidity of the ZrO2 surface, and the extent of this was followed by isopropanol temperature-programmed desorption with online mass spectrometry (IPA-TPD/MS; and by diffuse reflectance UV-Vis-IR). Catalyst activity and selectivity were tested by temperature-programmed surface reaction (TPSR) and under steady-state reaction conditions. The work has demonstrated that ZnZrOx with optimized ZnO distribution preserves the active Au-Ox surface species under reaction conditions and suppresses undesired dehydration reactions. Addition of gold on the bare zirconia support passivates the acid sites catalyzing ethanol dehydration and introduces desired dehydrogenation sites at low temperatures (200 °C).
Original language | English |
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Pages (from-to) | 210-218 |
Number of pages | 9 |
Journal | ACS Catalysis |
Volume | 6 |
Issue number | 1 |
DOIs | |
State | Published - Jan 4 2016 |
Funding
We acknowledge the financial support of this work by the U.S. Department of Energy under Grant No. DE-FG02-05ER15730. C.W. thanks Dr. Y. Zhang and Dr. C. Settens at the Center for Material Science and Engineering of MIT; and Dr. H. Lin at the Center for Nanoscale Systems of Harvard University for their assistance with sample characterization. G.G. acknowledges the University of Genoa for financial support to conduct research at Tufts University. Aberration-corrected electron microscopy research at Oak Ridge National Laboratory was sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, Propulsion Materials Program.
Keywords
- acetaldehyde
- acetone
- ethanol dehydrogenation
- gold catalysts
- zinc oxide
- zirconia