| Title: | Insight into the interdependence of Ni and Al in bifunctional Ni/ZSM-5 catalysts by Ni K-edge XAS analysis |
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| Authors: | ID Arčon, Iztok (Author)
ID Vu, Hue-Tong (Author)
ID Dražić, Goran (Author)
ID Volavšek, Janez (Author)
ID Mali, Gregor (Author)
ID Zabukovec Logar, Nataša (Author)
ID Novak Tušar, Nataša (Author) |
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| Files: |  https://feza2023.org/en/
Description: Dostop z geslom
https://feza2023.org/en/.
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| Language: | English |
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| Work type: | Unknown |
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| Typology: | 1.12 - Published Scientific Conference Contribution Abstract |
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| Organization: | UNG - University of Nova Gorica
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| Abstract: | Catalyst design is crucial for improving catalytic activity and product selectivity. In a bifunctional Ni/ZSM-5
zeolite type catalyst, catalytic properties are usually tuned via varying Al and Ni contents [1]. While changes in
acid properties associated with Al sites are usually closely investigated, Ni phases, however, receive inadequate
attention. Herein, we present a systematic structural study of Ni in the Ni/ZSM-5 materials by Ni K-edge
XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure) analyses,
to monitor the local structure and chemical state of Ni species in the catalysts. In combination with XRD and
TEM we resolved the changes in the local environment of Ni species induced by the different Al contents of
the parent ZSM-5 prepared by a “green”, template free technique [2].
Ni species in Ni/ZSM-5 exist as NiO crystals (3–50 nm) and as charge compensating Ni2+ cations. The Ni Kedge
XANES and EXAFS results enabled the quantification of Ni-containing species. At a low Al to Si ratio
(nAl/nSi < 0.04), the NiO nanoparticles predominate in the samples and account for over 65% of Ni phases.
However, NiO is outnumbered by Ni2+ cations attached to the zeolite framework in ZSM-5 with a high Al to Si
ratio (nAl/nSi = 0.05) due to a higher number of framework negative charges imparted by Al. The obtained
results show that the number of highly reducible and active NiO crystals is strongly correlated with the
framework Al sites present in ZSM-5 zeolites, which depend greatly on the synthesis conditions. Therefore,
this kind of study is beneficial for any further investigation of the catalytic activities of Ni/ZSM-5 and other
metal-modified bifunctional catalysts. |
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| Keywords: | Ni/ZSM-5 catalysts, Ni EXAFS, XANES |
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| Year of publishing: | 2023 |
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| Number of pages: | 1 str. |
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| PID: | 20.500.12556/RUNG-8439-d40c387c-56f9-fe84-9167-c15a8e5e4858  |
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| COBISS.SI-ID: | 164972291 |
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| UDC: | 54 |
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| NUK URN: | URN:SI:UNG:REP:N4DKWQAX |
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| Publication date in RUNG: | 19.09.2023 |
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| Views: | 1807 |
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| Downloads: | 5 |
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