Repozitorij Univerze v Novi Gorici

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Naslov:Effect of Na, Cs and Ca on propylene epoxidation selectivity over CuOx/SiO2 catalysts studied by catalytic tests, in-situ XAS and DFT
Avtorji:ID Teržan, Janvit, KI (Avtor)
ID Huš, Matej, KI (Avtor)
ID Arčon, Iztok, UNG (Avtor)
ID Likozar, Blaž, KI (Avtor)
ID Djinović, Petar, KI (Avtor)
Datoteke: Gradivo nima datotek, ki so prostodostopne za javnost. Gradivo je morda fizično dosegljivo v knjižnici fakultete, zalogo lahko preverite v COBISS-u. Povezava se odpre v novem oknu
Jezik:Slovenski jezik
Vrsta gradiva:Delo ni kategorizirano
Tipologija:1.01 - Izvirni znanstveni članek
Organizacija:UNG - Univerza v Novi Gorici
Opis:This research focuses on epoxidation of propylene over pristine, Na, Ca and Cs modified CuOx/SiO2 catalysts using O2. The selectivity of the reaction is analyzed using a combination of catalytic tests, in-situ XAS and DFT calculations. The initially present subnanometer CuO clusters are present in all catalysts which re-disperse/flatten during reaction. During catalytic reaction, the Cu1+ becomes the predominant oxidation state. There is no correlation between propylene oxide (PO) selectivity and copper oxidation state. DFT analysis of the propylene reaction pathway revealed that Na, Cs, and Ca addition decreases the bonding strength of propylene to CuO and decreases the O2 activation barrier, while simultaneously increase the exothermicity of O2 dissociation. The Na induced Cu-O bond modification decreases the activation barrier from 0.87 to 0.71 eV for the oxametallacycle (OMC) ring closure (first step in the reaction pathway favoring selectivity towards PO) compared to pristine 5Cu catalyst. At the same time, we observed an increase (from 0.45 to 0.72 eV) of the barrier for the abstraction of allylic hydrogen. The opposite effect is achieved by Ca addition: the activation barrier for OMC ring closure increases to 1.08 eV and that for allylic hydrogen stripping decreases to 0.16 eV.
Ključne besede:Alkali modification, propylene epoxidation, reaction mechanism, copper oxide, activation barrier.
Verzija publikacije:Objavljena publikacija
Leto izida:2020
Št. strani:30
Številčenje:1
PID:20.500.12556/RUNG-5539-f4e021ed-9ad7-0807-3b82-d9b20515af64 Novo okno
COBISS.SI-ID:18333187 Novo okno
DOI:https://doi.org/10.1016/j.apsusc.2020.146854 Novo okno
NUK URN:URN:SI:UNG:REP:N6ZFJTN0
Datum objave v RUNG:05.06.2020
Število ogledov:2753
Število prenosov:0
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Gradivo je del revije

Naslov:Applied Surface Science
Leto izida:2020

Licence

Licenca:CC BY-NC-ND 4.0, Creative Commons Priznanje avtorstva-Nekomercialno-Brez predelav 4.0 Mednarodna
Povezava:http://creativecommons.org/licenses/by-nc-nd/4.0/deed.sl
Opis:Najbolj omejujoča licenca Creative Commons. Uporabniki lahko prenesejo in delijo delo v nekomercialne namene in ga ne smejo uporabiti za nobene druge namene.
Začetek licenciranja:05.06.2020

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