Fundamental Studies of Nitrogen Oxide Surface Chemistry: A Model System Approach Combining Experiments and Theory
EMSL Project ID
30469
Abstract
This program is aimed at the development of a fundamental understanding of catalytic nitrogen oxide (NOx) chemistry on base metal oxide surfaces. Special emphasis is on identifying new and unique chemistry associated with molecules containing unpaired electrons in their ground state. First we determine the optimal preparation conditions and the structural and compositional characteristics of base-metal oxide (e.g. BaO) nanostructures on well ordered oxide (in particular, Al2O3) substrates. Then we obtain detailed chemical kinetics data on idealized but well-characterized catalyst systems useful for understanding the important elementary reactions. For example, a molecular-level description of the adsorption and reaction of various NOx species (NO, NO2, N2O) on specific oxide surface "active sites", of relevance for a wide variety of catalytic NOx processes, is being obtained in this work. Specifically, we have been carrying out studies of NOx adsorption and reaction on well-characterized thin Al2O3 films (used as substrate oxides) grown on both NiAl(100), and NiAl(110) and BaO (base-metal oxide, deposited by RLAD) surfaces. RAIRS studies are aimed at identifying surface species that form in the interaction of NOx with both the substrate and the base-metal oxide surfaces. It also provides invaluable information on the formation mechanisms and stabilities of different NOx species formed. The interaction of of co-adsorbates (H2O, CO2) with both the base metal oxide nano structures and the oxide support materials can have a profound effect on the NOx chemistry of the systems studied. Therefore, understanding the interactions of these co-adsorbates with both the base metal oxides and the support is of particular interest. The NOx species that form on the base metal oxides will be affected by these co-adsorbates, thus the effect of the presence of co-adsorbates on the surface chemistry of NOx will be studied in detail. Recently we have initiated high field 27Al MAS NMR experiments, and DFT calculations in order to understand the interaction of BaO with the alumina surface, and the consequences of the strong BaO-alumina interaction on the NOx chemistry. These studies have already enhanced our understanding of the BaO structures that form on the alumina support at low coverages, and their interactions with NOx molecules.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2008-08-26
End Date
2011-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Understanding Automotive Exhaust Catalysts Using a Surface Science Approach: Model NOx Storage Materials
Szanyi J, CWW Yi, KK Mudiyanselage, and JH Kwak. 2013. "Understanding Automotive Exhaust Catalysts Using a Surface Science Approach: Model NOx Storage Materials." Topics in Catalysis 56(15-17):1420-1440. doi:10.1007/s11244-013-0152-9
Oxygen Coverage Dependence of NO Oxidation on Pt(111)
Kumudu Mudiyanselage, Cheol-Woo Yi, and Ja´nos Szanyi, "Oxygen Coverage Dependence of NO Oxidation on Pt(111)." Journal of Physical. Chemistry. C 2009, 113, 5766–5776. DOI: 10.1021/jp811520u
Understanding the nature of surface nitrates in BaO/γ-Al2O3 NOx storage materials: A combined experimental and theoretical study
Ja Hun Kwak , Donghai Mei, Cheol-Woo Yi, Do Heui, Kim, Charles H.F. Peden, Lawrence F. Allard,
János Szanyi, "Understanding the nature of surface nitrates in BaO/? -Al2O3 NOx storage
materials: A combined experimental and theoretical study." Journal of Catalysis 261 (2009) 17-22, DOI: 10.1016/j.jcat.2008.10.016
János Szanyi, "Understanding the nature of surface nitrates in BaO/? -Al2O3 NOx storage
materials: A combined experimental and theoretical study." Journal of Catalysis 261 (2009) 17-22, DOI: 10.1016/j.jcat.2008.10.016
Penta-coordinated Al3+ ions as preferential nucleation sites for BaO on γ-Al2O3: An ultra-high-magnetic field 27Al MAS NMR study
Ja Hun Kwak, Jian Zhi Hu, Do Heui Kim, Janos Szanyi, Charles H.F. Peden, "Penta-coordinated Al3+ ions as preferential nucleation sites for BaO on ? -Al2O3: An ultra-high-magnetic field 27Al MAS NMR study." Journal of Catalysis 251 (2007) 189–194. DOI: 10.1016/j.jcat.2007.06.029.
D2O Adsorption on an Ultrathin Alumina Film on NiAl(110)
Cheol-Woo Yi and Janos Szanyi, "D2O Adsorption on an Ultrathin Alumina Film on NiAl(110)." Journal of Physical Chemistry C 2007, 111, 17597-17602. DOI: 10.1021/jp074459s
Interaction of NO2 with BaO: From Cooperative Adsorption to Ba(NO3)2 Formation
Cheol-Woo Yi, Ja Hun Kwak, and Janos Szanyim "Interaction of NO2 with BaO: From Cooperative Adsorption to Ba(NO3)2 Formation." Journal of Physical Chemistry C 2007, 111, 15299-15305. DOI: 10.1021/jp074179c
Understanding Practical Catalysts Using a Surface Science Approach: The Importance of Strong Interaction between BaO and Al2O3 in NOx Storage Materials
Cheol-Woo Yi, Ja Hun Kwak, Charles H. F. Peden, Chongmin Wang, and Janos Szanyi, "Understanding Practical Catalysts Using a Surface Science Approach: The Importance of
Strong Interaction between BaO and Al2O3 in NOx Storage Materials." Journal of Physical Chemistry C, 2007, 111, 14942-14944. DOI: 10.1021/jp0763376
Strong Interaction between BaO and Al2O3 in NOx Storage Materials." Journal of Physical Chemistry C, 2007, 111, 14942-14944. DOI: 10.1021/jp0763376
Reactivity of a Thick BaO Film Supported on Pt(111): Adsorption and Reaction of NO2, H2O, and CO2
Mudiyanselage K, CWW Yi, and J Szanyi. 2009. "Reactivity of a Thick BaO Film Supported on Pt(111): Adsorption and Reaction of NO2, H2O and CO2." Langmuir 25(18):10820-10828. doi:10.1021/la901371g
Growth and Characterization of Barium Oxide Nanoclusters on YSZ(111)
Nachimuthu P, YJ Kim, SVNT Kuchibhatla, Z Yu, W Jiang, MH Engelhard, V Shutthanandan, J Szanyi, and S Thevuthasan. 2009. "Growth and characterization of barium oxide nanoclusters on YSZ(111)." Journal of Physical Chemistry C 113(32):14324-14328. doi:10.1021/jp9020068