Abstract
Alumina oxides assume prominent catalytic applications in a wide range of industrial processes. However, alumina surfaces also serve as potent promoters in the heterogeneous formation of the notorious environmentally-persistent free radicals (EPFR). Herein, we theoretically examine dissociative adsorption mechanisms of phenol molecules over Al 2 O 3 and hydrated Al 2 O 3 ·nH 2 O clusters that mimic dehydrated and hydrated alumina structures, respectively. We show that fission of the phenol's hydroxyl bond over dehydrated alumina systematically incurs lower energy barriers in reference to the hydrated structures. A 1,2-water elimination step marks the most feasible channel in the interaction of phenol with hydrated clusters. The relevance of the acidity sites to the catalytic activity of alumina is clearly supported by the finding that the catalytic activity of the alumina surface in producing the phenoxy/phenolate species reversibly correlates with the degree of hydroxyl coverage. Desorption of adsorbed phenolates requires sizable desorption energies, and thus is expected to facilitate surface-mediated condensation into dioxin-like moieties.
| Original language | English |
|---|---|
| Pages (from-to) | 52672-52683 |
| Number of pages | 12 |
| Journal | RSC Advances |
| Volume | 7 |
| Issue number | 83 |
| Early online date | 15 Nov 2017 |
| DOIs | |
| Publication status | Published - 2017 |
| Externally published | Yes |
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Formation of environmentally-persistent free radicals (EPFR) on α-Al 2 O 3 clusters. / Assaf, Niveen W.; Altarawneh, Mohammednoor; Radny, Marian W.; Al-Nu'Airat, Jomana; Dlugogorski, Bogdan Z.
In: RSC Advances, Vol. 7, No. 83, 2017, p. 52672-52683.Research output: Contribution to journal › Article › Research › peer-review
TY - JOUR
T1 - Formation of environmentally-persistent free radicals (EPFR) on α-Al 2 O 3 clusters
AU - Assaf, Niveen W.
AU - Altarawneh, Mohammednoor
AU - Radny, Marian W.
AU - Al-Nu'Airat, Jomana
AU - Dlugogorski, Bogdan Z.
PY - 2017
Y1 - 2017
N2 - Alumina oxides assume prominent catalytic applications in a wide range of industrial processes. However, alumina surfaces also serve as potent promoters in the heterogeneous formation of the notorious environmentally-persistent free radicals (EPFR). Herein, we theoretically examine dissociative adsorption mechanisms of phenol molecules over Al 2 O 3 and hydrated Al 2 O 3 ·nH 2 O clusters that mimic dehydrated and hydrated alumina structures, respectively. We show that fission of the phenol's hydroxyl bond over dehydrated alumina systematically incurs lower energy barriers in reference to the hydrated structures. A 1,2-water elimination step marks the most feasible channel in the interaction of phenol with hydrated clusters. The relevance of the acidity sites to the catalytic activity of alumina is clearly supported by the finding that the catalytic activity of the alumina surface in producing the phenoxy/phenolate species reversibly correlates with the degree of hydroxyl coverage. Desorption of adsorbed phenolates requires sizable desorption energies, and thus is expected to facilitate surface-mediated condensation into dioxin-like moieties.
AB - Alumina oxides assume prominent catalytic applications in a wide range of industrial processes. However, alumina surfaces also serve as potent promoters in the heterogeneous formation of the notorious environmentally-persistent free radicals (EPFR). Herein, we theoretically examine dissociative adsorption mechanisms of phenol molecules over Al 2 O 3 and hydrated Al 2 O 3 ·nH 2 O clusters that mimic dehydrated and hydrated alumina structures, respectively. We show that fission of the phenol's hydroxyl bond over dehydrated alumina systematically incurs lower energy barriers in reference to the hydrated structures. A 1,2-water elimination step marks the most feasible channel in the interaction of phenol with hydrated clusters. The relevance of the acidity sites to the catalytic activity of alumina is clearly supported by the finding that the catalytic activity of the alumina surface in producing the phenoxy/phenolate species reversibly correlates with the degree of hydroxyl coverage. Desorption of adsorbed phenolates requires sizable desorption energies, and thus is expected to facilitate surface-mediated condensation into dioxin-like moieties.
UR - http://www.scopus.com/inward/record.url?scp=85034567820&partnerID=8YFLogxK
U2 - 10.1039/c7ra09527a
DO - 10.1039/c7ra09527a
M3 - Article
VL - 7
SP - 52672
EP - 52683
JO - RSC Advances: an international journal to further the chemical sciences
JF - RSC Advances: an international journal to further the chemical sciences
SN - 2046-2069
IS - 83
ER -