Mechanistic Effects of Water on the Fe-Catalyzed Hydrodeoxygenation of Phenol. The Role of Br�nsted Acid Sites [electronic resource]

• Ngôn ngữ: eng
• Ký hiệu phân loại: 621.47 Solar-energy engineering
• Thông tin xuất bản: Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2018
• Mô tả vật lý: Size: p. 2200-2208 : , digital, PDF file.
• Bộ sưu tập: Metadata
• ID: 263080
• Chủ đề: 1. 09 biomass fuels; 2. 71 classical and quantum mechanics, general physics; 3. 74 atomic and molecular physics; 4. 75 condensed matter physics, superconductivity and superfluidity; 5. 97 mathematics and computing

Tóm tắt

 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 Br�nsted 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 Br�nsted acid sites via surface doping.