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Title:Insight into the interdependence of Ni and Al in bifunctional Ni/ZSM-5 catalysts by Ni K-edge XAS analysis
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)
Description: Dostop z geslom
Work type:Unknown
Typology:1.12 - Published Scientific Conference Contribution Abstract
Organization:UNG - University of Nova Gorica
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.
Keywords:Ni/ZSM-5 catalysts, Ni EXAFS, XANES
Year of publishing:2023
Number of pages:1 str.
PID:20.500.12556/RUNG-8439-d40c387c-56f9-fe84-9167-c15a8e5e4858 New window
COBISS.SI-ID:164972291 New window
Publication date in RUNG:19.09.2023
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Record is a part of a monograph

Title:FEZA 2023 : 9th Conference of the Federation of the European Zeolite Associations, portorž-Portorose Slovenija, 2-6 July 2023
Editors:Nataša Zabukovec Logar, Vesna Rakić, Josip Bronić
Place of publishing:[S. l.
Publisher:Slovenian, Croatian and Serbian Zeolite Associations]
Year of publishing:2023
COBISS.SI-ID:158641155 New window

Secondary language

Keywords:Ni/ZSM-5 catalysts, Ni EXAFS, XANES