Dissertation
ATOMISTIC ELUCIDATION OF THE SYNERGY WITHIN NOBLE METAL PROMOTED-FE CATALYSTS FOR THE HYDRODEOXYGENATION OF PHENOLIC COMPOUNDS
Doctor of Philosophy (PhD), Washington State University
01/2015
Handle:
https://hdl.handle.net/2376/108499
Abstract
The synergy within noble metal doped Fe catalysts and its effect on the hydrodeoxygenation of phenols was investigated from first principles by studying: (1) the adsorption of aromatics on monometallic and bimetallic surfaces, (2) the reduction of doped Fe2O3, and (3) the elementary reaction mechanisms for phenols on monometallic surfaces. The results from the adsorption studies showed that Fe (110) distorted the C-O bonds to a greater degree than Pd (111). On the bimetallic surfaces (Pd/Fe, Pt/Fe, Pt/Ni), the adsorption of aromatics was found to be significantly weakened on the noble metal dopants relative to adsorption on both the base metals in the bimetallic surfaces (Fe or Ni) and monometallic noble metal surfaces. A d-band analysis of the bimetallic surfaces showed why adsorption might be weakened on the noble metal dopants: their d-band center significantly shifted away from the Fermi level as compared to that of the pure noble metal. The elementary mechanism for the hydrodeoxygenation of phenol on Fe and Pd monometallic surfaces was investigated. Furthermore, the thermal decomposition of guaiacol on a Pt monometallic surface was also investigated and the results were compared to experiments performed on the well-defined Pt (111) surface. These studies found Pd and Pt to be highly inactive for the hydrodeoxygenation of phenol and guaiacol, respectively; however, Fe was found to be highly active. Additionally, the Pt study showed that theory can effectively identify the complex decomposition mechanism for guaiacol on a well-defined surface. While these studies elucidated the function of Fe in the bimetallic catalysts, this did not explain the function of the noble metal dopant. Studying Pd doped Fe2O3, it was determined that Pd enhanced Fe2O3 reduction by weakening the surface Fe-O bonds via donating electrons to the surface Fe and preferentially bonding with surface oxygen. Overall, the observed catalytic synergy within noble metal doped Fe catalysts was found to be due to: (1) the high activity of Fe surfaces for adsorbing phenols and cleaving C-O bonds and (2) the protection of the metallic Fe from oxidation via the noble metal dopant’s disruption of surface Fe-O bonds.
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Details
- Title
- ATOMISTIC ELUCIDATION OF THE SYNERGY WITHIN NOBLE METAL PROMOTED-FE CATALYSTS FOR THE HYDRODEOXYGENATION OF PHENOLIC COMPOUNDS
- Creators
- Alyssa Joy Rose Hensley
- Contributors
- Jean-Sabin McEwen (Advisor)Yong Wang (Committee Member)Kirk Peterson (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Chemical Engineering and Bioengineering, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 455
- Identifiers
- 99900581837001842
- Language
- English
- Resource Type
- Dissertation