Continuous wave (CW) and pulsed electron paramagnetic resonance (EPR) spectroscopy are used to investigate the nature of vanadium species on V2O5/TiO2 catalysts prepared via wet impregnation and gas-phase grafting routes. CW EPR experiments show in both cases the formation of VO2+ vanadyl ions upon reaction with ammonia; moreover, phase memory time filtered echo-detected EPR experiments at X- and Q-band frequencies provide direct experimental evidence for the reduction of the TiO2 substrate and the formation of Ti3+ ions. X-band hyperfine sublevel correlation (HYSCORE) experiments are used to investigate the local environment of VO2+ ions. The direct nitrogen coordination of residual ammonia fragments in the equatorial plane of the vanadyl ion is demonstrated.

Exploring the Interaction of Ammonia with Supported Vanadia Catalysts by Continuous Wave and Pulsed Electron Paramagnetic Resonance Spectroscopy

LAGOSTINA, VALERIA;Paganini, Maria Cristina;Chiesa, Mario;Giamello, Elio
2019-01-01

Abstract

Continuous wave (CW) and pulsed electron paramagnetic resonance (EPR) spectroscopy are used to investigate the nature of vanadium species on V2O5/TiO2 catalysts prepared via wet impregnation and gas-phase grafting routes. CW EPR experiments show in both cases the formation of VO2+ vanadyl ions upon reaction with ammonia; moreover, phase memory time filtered echo-detected EPR experiments at X- and Q-band frequencies provide direct experimental evidence for the reduction of the TiO2 substrate and the formation of Ti3+ ions. X-band hyperfine sublevel correlation (HYSCORE) experiments are used to investigate the local environment of VO2+ ions. The direct nitrogen coordination of residual ammonia fragments in the equatorial plane of the vanadyl ion is demonstrated.
2019
Inglese
Esperti anonimi
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7861
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Lagostina, Valeria; Paganini, Maria Cristina; Chiesa, Mario; Giamello, Elio
info:eu-repo/semantics/article
partially_open
03-CONTRIBUTO IN RIVISTA::03A-Articolo su Rivista
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1696575
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