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

Abstract

In this report 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.

Authors:
 [1];  [1]
  1. University of Minnesota, Minneapolis, MN (United States)
Publication Date:
Research Org.:
Univ. of Minnesota, Minneapolis, MN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
OSTI Identifier:
1533927
Alternate Identifier(s):
OSTI ID: 1359264
Grant/Contract Number:  
SC0008418
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Catalysis
Additional Journal Information:
Journal Volume: 344; Journal Issue: C; Journal ID: ISSN 0021-9517
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Brønsted acid; dehydration; molybdenum carbide; tungsten carbide; interstitial carbide; catalysis; site density; oxophilic; transition metal

Citation Formats

Sullivan, Mark M., and Bhan, Aditya. Acid site densities and reactivity of oxygen-modified transition metal carbide catalysts. United States: N. p., 2016. Web. doi:10.1016/j.jcat.2016.09.012.
Sullivan, Mark M., & Bhan, Aditya. Acid site densities and reactivity of oxygen-modified transition metal carbide catalysts. United States. https://doi.org/10.1016/j.jcat.2016.09.012
Sullivan, Mark M., and Bhan, Aditya. 2016. "Acid site densities and reactivity of oxygen-modified transition metal carbide catalysts". United States. https://doi.org/10.1016/j.jcat.2016.09.012. https://www.osti.gov/servlets/purl/1533927.
@article{osti_1533927,
title = {Acid site densities and reactivity of oxygen-modified transition metal carbide catalysts},
author = {Sullivan, Mark M. and Bhan, Aditya},
abstractNote = {In this report 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.},
doi = {10.1016/j.jcat.2016.09.012},
url = {https://www.osti.gov/biblio/1533927}, journal = {Journal of Catalysis},
issn = {0021-9517},
number = C,
volume = 344,
place = {United States},
year = {Wed Sep 28 00:00:00 EDT 2016},
month = {Wed Sep 28 00:00:00 EDT 2016}
}

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Cited by: 28 works
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