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Title: Activation Mechanism and Surface Intermediates during Olefin Metathesis by Supported MoOx/Al 2O 3 Catalysts

Abstract

The activation of supported MoO x/Al 2O 3 catalysts and the resulting surface intermediates were examined with in situ DRIFTS during olefin metathesis reaction conditions, aided by C 3D 6-C 3H 6 isotopically labeled switching, C 2H 4-C 4H 8 titration, and temperature programmed reaction experiments. The studies shows that activation by propylene of the surface MoO x sites on Al 2O 3 initiates by forming surface isopropoxide species that subsequently dehydrogenate to acetone and surface Mo-OH. Desorption of acetone from the catalyst surface reduces the Mo +6 sites to Mo +4 sites, creating a vacancy for coordination of the next CH 2=CHCH 3 molecule. Oxidative addition from subsequent adsorption of propylene on the surface Mo +4 sites results in formation of surface Mo=CH 2 and Mo=CHCH3 reactive intermediates, oxidizing the reduced surface molybdena sites back to Mo +6. This study demonstrates the activation mechanism and surface intermediates during olefin metathesis by supported MoO x/Al 2O 3 catalysts under reaction conditions.

Authors:
 [1]; ORCiD logo [2]
  1. Lehigh Univ., Bethlehem, PA (United States); Honeywell UOP, Des Plaines, IL (United States)
  2. Lehigh Univ., Bethlehem, PA (United States)
Publication Date:
Research Org.:
Lehigh Univ., Bethlehem, PA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1510503
Grant/Contract Number:  
SC0014510
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: XXXX; Journal Issue: XXX; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Chakrabarti, Anisha, and Wachs, Israel E. Activation Mechanism and Surface Intermediates during Olefin Metathesis by Supported MoOx/Al2O3 Catalysts. United States: N. p., 2019. Web. doi:10.1021/acs.jpcc.9b02426.
Chakrabarti, Anisha, & Wachs, Israel E. Activation Mechanism and Surface Intermediates during Olefin Metathesis by Supported MoOx/Al2O3 Catalysts. United States. doi:10.1021/acs.jpcc.9b02426.
Chakrabarti, Anisha, and Wachs, Israel E. Mon . "Activation Mechanism and Surface Intermediates during Olefin Metathesis by Supported MoOx/Al2O3 Catalysts". United States. doi:10.1021/acs.jpcc.9b02426.
@article{osti_1510503,
title = {Activation Mechanism and Surface Intermediates during Olefin Metathesis by Supported MoOx/Al2O3 Catalysts},
author = {Chakrabarti, Anisha and Wachs, Israel E.},
abstractNote = {The activation of supported MoOx/Al2O3 catalysts and the resulting surface intermediates were examined with in situ DRIFTS during olefin metathesis reaction conditions, aided by C3D6-C3H6 isotopically labeled switching, C2H4-C4H8 titration, and temperature programmed reaction experiments. The studies shows that activation by propylene of the surface MoOx sites on Al2O3 initiates by forming surface isopropoxide species that subsequently dehydrogenate to acetone and surface Mo-OH. Desorption of acetone from the catalyst surface reduces the Mo+6 sites to Mo+4 sites, creating a vacancy for coordination of the next CH2=CHCH3 molecule. Oxidative addition from subsequent adsorption of propylene on the surface Mo+4 sites results in formation of surface Mo=CH2 and Mo=CHCH3 reactive intermediates, oxidizing the reduced surface molybdena sites back to Mo+6. This study demonstrates the activation mechanism and surface intermediates during olefin metathesis by supported MoOx/Al2O3 catalysts under reaction conditions.},
doi = {10.1021/acs.jpcc.9b02426},
journal = {Journal of Physical Chemistry. C},
number = XXX,
volume = XXXX,
place = {United States},
year = {2019},
month = {4}
}

Journal Article:
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This content will become publicly available on April 29, 2020
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