Nitrogen oxides and SO2 adsorption on Au/MOR catalyst: Adsorption sites, thermodynamic and vibrational frequencies. ONIOM study

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 2012-11, Vol.363-364, p.380-386
• Main Authors: Sierraalta, Anibal, Diaz, Lenin, Añez, Rafael
• Format: Article
• Language: English
• Subjects: Catalysis; Chemistry; DeNOx; DFT; Exact sciences and technology; General and physical chemistry; Gold; Ion-exchange; Mordenite; ONIOM; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Zeolites: preparations and properties
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2012.07.014

[Display omitted] ► Al crystallography positions do not have influence on Au species properties. ► Thermodynamically, NO adsorption is stronger on [Au]+ than on aggregates [Au3]+. ► According DFT calculations, at low Au content, the catalyst is able to adsorb SO2. Quantum chemical calculations were carried out to determine geometries, vibrational frequencies and adsorption energies of NO, NO2, N2O, and SO2 molecules on a gold-exchanged mordenite catalyst (Au/MOR). The results show that the adsorption energies are greater on [Au]+ than on [Au3]+ species. In general, the charge transferred from Au to the adsorbed molecules is higher for [Au3]+ than for [Au]+. It is shown for first time, that the SO2 adsorption is thermodynamically favored on the [Au]+ species, but not on [Au3]+ species. Therefore at low Au content, the Au/MOR catalyst could be able to adsorb SO2.