Mechanistic Effects of Water on the Fe-Catalyzed Hydrodeoxygenation of Phenol. The Role of Brønsted Acid Sites
- Washington State Univ., Pullman, WA (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
A mechanistic understanding of the roles of water is essential for developing highly active and selective catalysts for hydrodeoxygenation (HDO) reactions because water is ubiquitous in such reaction systems. Here we present a study for phenol HDO on Fe catalysts using density functional theory which examines the effect of water on three elementary pathways for phenol HDO using an explicit solvation model. The presence of water is found to significantly decrease activation barriers required by hydrogenation reactions via two pathways. First, proton transfer in the hydrogen bonding network of the liquid water phase is nearly barrierless, which significantly promotes the direct tautomerization of phenol. Second, due to the high degree of oxophilicity on Fe, liquid water molecules are found to be easily dissociated into surface hydroxyl groups that can act as Brønsted acid sites. Furthermore, these sites dramatically promote hydrogenation reactions on the Fe surface. As a result, hydrogen-assisted dehydroxylation becomes the dominant phenol HDO pathway. This work provides fundamental insights into aqueous phase HDO of biomass-derived oxygenates over Fe-based catalysts; e.g., the activity of Fe-based catalysts can be optimized by tuning the surface coverage of Brønsted acid sites via surface doping.
- Research Organization:
- Washington State Univ., Pullman, WA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division
- Grant/Contract Number:
- SC0014560; AC05-06OR23100; FG02-05ER15712
- OSTI ID:
- 1772335
- Journal Information:
- ACS Catalysis, Vol. 8, Issue 3; ISSN 2155-5435
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
75 CONDENSED MATTER PHYSICS
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97 MATHEMATICS AND COMPUTING
hydrodeoxygenation
mechanistic effect of liquid water
phenol
Fe catalyst
density functional theory
reaction pathways
Brønsted acid sites
redox reactions
chemical reactions
aromatic compounds
hydrogenation