Acid site densities and reactivity of oxygen-modified transition metal carbide catalysts

Mark M. Sullivan, Aditya Bhan

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Acidic properties of β-Mo2C, α-Mo2C, W2C, and WC were quantified by assessing the kinetics of isopropanol (IPA) dehydration at 415 K either (i) under inert He/Ar atmosphere or (ii) with 13 kPa O2 co-feed. Dehydration kinetics were zero-order with respect to IPA for all catalysts and under all reaction conditions. Intrinsic activation energies were similar across all catalysts (89–104 kJ mol−1). Acid site densities calculated via in situ 2,6-di-tert-butylpyridine (DTBP) titration were used to normalize dehydration turnover frequencies (TOF). O2 co-feed increased dehydration rates per gram by an order of magnitude for all catalysts tested, but TOF remained invariant within a factor of ∼2. Mo- and W-based carbides showed similar dehydration kinetics regardless of O2 co-feed, and O2 co-feed did not alter bulk carbidic structure as noted by X-ray diffraction. Brønsted acid site provenance results from the oxophilicity of Mo and W carbides.

Original languageEnglish (US)
Pages (from-to)53-58
Number of pages6
JournalJournal of Catalysis
Volume344
DOIs
StatePublished - Dec 1 2016

Bibliographical note

Funding Information:
This research was supported by Office of Basic Energy Sciences, the U.S. Department of Energy under award number no. DE- SC0008418 (DOE Early Career Program). Part of this work was carried out in the College of Science and Engineering Characterization Facility, University of Minnesota, which has received capital equipment funding from the NSF through the MRSEC program. We thank Javier Garcia Barriocanal for assistance with the X-ray diffraction studies, Rick Knurr for assistance with the ICP-OES characterization, and Bing Luo for assistance with the XPS characterization.

Publisher Copyright:
© 2016 Elsevier Inc.

Keywords

  • Brønsted acid
  • Catalysis
  • Dehydration
  • Interstitial carbide
  • Molybdenum carbide
  • Oxophilic
  • Site density
  • Transition metal
  • Tungsten carbide

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