Diverse Mechanistic Pathways in Single-Site Heterogeneous Catalysis: Alcohol Conversions Mediated by a High-Valent Carbon-Supported Molybdenum-Dioxo Catalyst

Jiaqi Li, Anusheela Das, Qing Ma, Michael J. Bedzyk, Yosi Kratish*, Tobin J. Marks

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

With the increase in the importance of renewable resources, chemical research is shifting focus toward substituting petrochemicals with biomass-derived analogues and platform-molecule transformations such as alcohol processing. To these ends, in-depth mechanistic understanding is key to the rational design of catalytic systems with enhanced activity and selectivity. Here we discuss in detail the structure and reactivity of a single-site active carbon-supported molybdenum-dioxo catalyst (AC/MoO2) and the mechanism(s) by which it mediates alcohol dehydration. A range of tertiary, secondary, and primary alcohols as well as selected bio-based terpineols are investigated as substrates under mild reaction conditions. A combined experimental substituent effect/kinetic/kinetic isotope effect/EXAFS/DFT computational analysis indicates that (1) water assistance is a key element in the transition state; (2) the experimental kinetic isotopic effect and activation enthalpy are 2.5 and 24.4 kcal/mol, respectively, in good agreement with the DFT results; and (3) several computationally identified intermediates including Mo-oxo-hydroxy-alkoxide and cage-structured long-range water-coordinated Mo-dioxo species are supported by EXAFS. This structurally and mechanistically well-characterized single-site system not only effects efficient transformations but also provides insight into rational catalyst design for future biomass processes.

Original languageEnglish (US)
Pages (from-to)1247-1257
Number of pages11
JournalACS Catalysis
Volume12
Issue number2
DOIs
StatePublished - Jan 21 2022

Keywords

  • alcohol dehydration
  • dehydrogenation
  • heterogeneous catalysis
  • molybdenum
  • single-site catalyst

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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