Mechanistic Origins of Unselective Oxidation Products in the Conversion of Propylene to Acrolein on Bi2Mo3O12

Linh Bui, Reetam Chakrabarti, Aditya Bhan

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

A reaction network detailing the formation and consumption of all C1-C3 products of propylene oxidation on Bi2Mo3O12 at 623 K is developed to show that acrolein, acetaldehyde, acetone, and acetic acid are direct oxidation products of propylene while acrylic acid and ethylene are secondary products. Coprocessing acetaldehyde, acetone, acrylic acid, and acetic acid, separately, with propylene, oxygen, and water revealed (i) the existence of overoxidation reactions of acrolein to acrylic acid and ethylene and oxidation pathways from acetone to acetaldehyde and acetic acid, (ii) the promotional effects of water on the synthesis rates of acetaldehyde from acrolein, acetone from propylene, and acetic acid from acetaldehyde and acrylic acid, and (iii) the inhibitory effects of water on the decomposition of acetic acid to COx and acrylic acid to acetaldehyde and ethylene. A kinetic model is developed to quantitatively capture the kinetic behavior of all species using pseudo-first-order rate expressions in the organic reactant for all reaction pathways; additional promotional and inhibitory dependencies on water pressure were added to describe the kinetics of reaction rates affected by water. Based on the proposition that multiple types of active sites exist on the mixed metal oxide surface during propylene oxidation, a detailed mechanistic network is postulated that describes all molecular transformations with relevant surface intermediates and provides critical insights into the underlying pathways involved in overoxidation and C-C bond scission reactions.

Original languageEnglish (US)
Pages (from-to)6567-6580
Number of pages14
JournalACS Catalysis
Volume6
Issue number10
DOIs
StatePublished - Oct 7 2016

Bibliographical note

Publisher Copyright:
© 2016 American Chemical Society.

Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.

Keywords

  • acrolein
  • bismuth molybdate
  • byproducts
  • kinetic model
  • propylene oxidation
  • reaction network

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