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NiAu Single Atom Alloys for the Non-oxidative Dehydrogenation of Ethanol to Acetaldehyde and Hydrogen

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Abstract

Gold is examined here as an alternative to copper for the selective dehydrogenation of ethanol to acetaldehyde and hydrogen. Despite its high selectivity, gold is only active at temperatures higher than 250 °C for this reaction. We demonstrate that addition of a small amount of Ni on either supported or unsupported Au surfaces induces resistance to sintering, along with a beneficial effect on the catalytic activity. NiAu alloys prepared here with Ni as the minority component to the limit of atomic dispersion in the gold surfaces, catalyze the reaction beginning below 150 °C. A significant decrease of the apparent activation energy from 96 ± 3 kJ/mol for the monometallic Au to 59 ± 5 kJ/mol for the alloy was found. The Ni dispersion and concentration as a function of gas environment was followed by in situ DRIFTS and by XPS. The stability of the catalyst morphology was investigated through post-reaction microscopy imaging and long-term stability tests under reaction conditions. As shown via dynamic reaction experiments, acetaldehyde and H2 were selectively produced up to 280 °C. A small drop of selectivity at higher temperatures is attributed to the formation of Ni clusters, as proven by CO-DRIFTS on the used sample. Comparison with samples of higher Ni loading, where Ni clusters are formed, clearly shows that they catalyze the undesired full decomposition of ethanol to CO, CH4, and H2.

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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. Work at LLNL was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. TEM and SEM imaging was performed at Harvard University’s Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Infrastructure Network (NNIN), which is supported by the National Science Foundation under NSF Award No. 1541959.

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  1. Junjun Shan

    Present address: NICE America Research, Inc., Mountain View, CA, 94043, USA

Authors and Affiliations

  1. Department of Chemical and Biological Engineering, Tufts University, Medford, MA, 02155, USA

    Georgios Giannakakis, Antonios Trimpalis, Junjun Shan, Sufeng Cao, Jilei Liu & Maria Flytzani-Stephanopoulos

  2. Nanoscale Synthesis and Characterization Laboratory, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA

    Zhen Qi, Jianchao Ye & Juergen Biener

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  1. Georgios Giannakakis
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Giannakakis, G., Trimpalis, A., Shan, J. et al. NiAu Single Atom Alloys for the Non-oxidative Dehydrogenation of Ethanol to Acetaldehyde and Hydrogen. Top Catal 61, 475–486 (2018). https://doi.org/10.1007/s11244-017-0883-0

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