Effect of the Nuclearity and Coordination of Cu and Fe Sites in beta Zeolites on the Oxidation of Hydrocarbons

0524176 - ÚFCH JH 2021 RIV US eng J - Journal Article
Sazama, Petr - Morávková, Jaroslava - Sklenák, Štěpán - Vondrová, Alena - Tabor, Edyta - Sádovská, Galina - Pilař, Radim
Effect of the Nuclearity and Coordination of Cu and Fe Sites in beta Zeolites on the Oxidation of Hydrocarbons.
ACS Catalysis. Roč. 10, č. 7 (2020), s. 3984-4002. ISSN 2155-5435. E-ISSN 2155-5435
R&D Projects: GA ČR GA18-20303S; GA MŠMT(CZ) LM2015073; GA MŠMT(CZ) EF16_013/0001821
Grant - others:Ga MŠk(CZ) LM2015070
Institutional support: RVO:61388955
Keywords : selective catalytic-reduction * volatile organic-compounds * initio molecular-dynamics * total-energy calculations * copper active-sites * low-temperature * n2o decomposition * methane oxidation * zsm-5 zeolite * bea zeolite * Cu zeolite * Fe zeolite * methane oxidation
OECD category: Physical chemistry
Impact factor: 13.084, year: 2020
Method of publishing: Limited access

Cu and Fe zeolites can activate oxygen for oxidative reactions of methane and stable hydrocarbon molecules. Here, we analyzed the activity of Cu and Fe sites with various nuclearities and coordinations in *BEA zeolites toward complete oxidation of methane, toluene, and ethanol by molecular oxygen. Spectral analysis of the interaction of methane with the individual Cu and Fe sites and a kinetic study show that the oxidation of methane is catalyzed by different active sites with different activation energies. In the low-temperature region (225-325 degrees C), the activity is primarily caused by reactive bridging oxygen atoms in dimeric Cu and Fe clusters. Isolated Fe3+-oxo ions in the octahedral coordination and Cu2+ partially charge-balanced by the framework with less rigid redox states contribute to the activity at higher temperatures of >= 350 degrees C. The isolated Fe3+-oxo ions tetrahedrally coordinated to the framework oxygen and the bare Cu2+ ions charge-balanced exclusively by the framework are strongly stabilized and cannot act as active sites. Oxidation of the hydrocarbons over both the dimeric and isolated Cu and Fe active sites is nonspecific with practically barrierless consecutive reactions of already activated molecules and therefore fully CO2-selective for all of the hydrocarbons in an excess of oxygen.
Permanent Link: http://hdl.handle.net/11104/0308541