(689e) Non-Oxidative Dehydrogenation of Ethanol to Acetaldehyde and Hydrogen on Nickel-Gold Single Atom Alloys
AIChE Annual Meeting
2018
2018 AIChE Annual Meeting
Catalysis and Reaction Engineering Division
Atomically Dispersed Supported Metal Catalysts II
Thursday, November 1, 2018 - 4:54pm to 5:15pm
Au has been studied as an alternative to Cu, as it provides enhanced stability and exhibits 100% selectivity even at high temperatures. These benefits come at the cost of low conversion, as the catalyst is only active when in specific size4 and at elevated temperatures regardless of the support5. In our recent work6 we demonstrated how to successfully deposit single atoms of Ni in the Au surface, forming NiAu single atom alloys (SAAs). The addition of Ni isolated atoms prevented sintering of Au existing in either nanoparticles or nanoporous form. At the same time, it lowered the activation energy significantly (from 96±3 to 59±5 kJ/mol), while at the same time the high selectivity induced by Au was maintained even at high temperatures (280 â), at which point Ni forms cluster that catalyze the ethanol decomposition to CO, CH4 and H2.
In the present work, we aim to further study NiAu SAAs under the specific reaction. First, we confirm the atomic dispersion of Ni in Au surfaces via CO-DRIFTS and EXAFS on the fresh and used materials up to 250 â. PdAu SAAs, which have been recently reported as promising hydrogenation catalysts7 are also tested under similar reaction conditions for comparison. Unlike Ni, Pd atoms effect on the catalytic activity is not as equally apparent, as indicated by activation energy measurements and Ethanol DRIFTS. The effect of water as a potential co-catalyst has also been examined, as it had been reported to be successful in promoting the activity of other SAAs in dehydrogenation reactions, namely PdCu in methanol dehydrogenation8 and PtCu9 in formic acid dehydrogenation. Contrary to the latter, water does not activate ethanol at lower temperatures, only acting as a reactant at higher temperatures in the ethanol steam reforming reaction. Last, this work is aided by surface science techniques (TPD), as well as theoretical contributions (DFT), providing a deeper understanding of the system.
Acknowledgements: This material is based upon work supported as part of the Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE- SC0012573.
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