Structure and site evolution of molybdenum carbide catalysts upon exposure to oxygen

Mark M. Sullivan, Jacob T. Held, Aditya Bhan

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63 Scopus citations


Acid site densities could be reversibly tuned by a factor of ∼30 using an O2 co-feed, which reversibly creates Brønsted acid sites on the carbide surface without altering the bulk crystal structure of 2-5 nm Mo2C crystallites. Unimolecular isopropanol (IPA) dehydration at 415 K, a probe reaction, occurred on Brønsted acid sites of these oxygen-modified carbides with an intrinsic activation energy of 93 ± 1.3 kJ mole-1 via an E2 elimination mechanism with a kinetically-relevant step of β-hydrogen scission. Site densities were estimated via in situ 2,6-di-tert-butylpyridine (DTBP) titration and used to calculate a turnover frequency (TOF) of 0.1 s-1, which was independent of site density. Oxygen co-processing allows for facile in situ tunability of acidic and metallic sites on highly oxophilic metal carbides.

Original languageEnglish (US)
Pages (from-to)82-91
Number of pages10
JournalJournal of Catalysis
StatePublished - Jun 1 2015

Bibliographical note

Publisher Copyright:
© 2015 Elsevier B.V. All rights reserved.


  • Bifunctional catalyst
  • Brønsted acid
  • Dehydration
  • Interstitial carbide
  • Molybdenum carbide
  • Oxophilic
  • Site density
  • Transition metal

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