Abstract
The catalytic behavior of oxide-supported metal oxide species depends on the nature of the support and the presence of co-catalysts. We use density functional theory (DFT) to explore the relationship between the structure and chemical behavior of vanadium oxide in light of its industrial use for the selective catalytic reduction of nitric oxide with ammonia (NO-SCR). The relative stabilities of dispersed VOX monomers, dimers, and long-chain oligomers on two model oxide support surfaces with similar structure but drastically different chemical behavior, α-Al2O3 (0001) and α-Fe2O3 (0001), are determined. The effect of added tungsten, known to promote NO-SCR, is also investigated on the relatively inert α-Al2O3 (0001) support. We find that the adsorption behavior of NH3, representing the first step of the NO-SCR reaction, depends strongly on the VOX local structure. Protonation of NH3 to NH4+ over surface hydroxyls is energetically favorable over VOX-WOX dimers and VOX oligomers, which are stabilized by the reducible α-Fe2O3 (0001) support.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 41-50 |
| Number of pages | 10 |
| Journal | Surface Science |
| Volume | 651 |
| DOIs | |
| State | Published - Sep 1 2016 |
Funding
M.E.M. was supported by a National Science Foundation Graduate Research Fellowship under Grant DGE-0824162 . M.E.M. and D.E.E. were supported in part by the Institute for Catalysis in Energy Processes (U.S. Department of Energy (DOE) under Contract DE-FG02-03ER15457 ). Computational equipment support was provided by the Initiative for Sustainability and Energy at Northwestern University. Atomic structure and charge density plots were made using VESTA software [73] .
Keywords
- Ammonia adsorption
- Density functional theory
- Electronic structure
- Nitric oxide reduction
- Oxide support
- Vanadium oxide
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry