Enhancement effect of bimetallic amide K₂Mn(NH₂)₄ and in-situ formed KH and Mn₄N on the dehydrogenation/hydrogenation properties of L–Mg–N–H system
Publication date
2019-08-19
Document type
Forschungsartikel
Author
Gizer, Gökhan
Cao, Hujun
Pistidda, Claudio
Santoru, Antonio
Zhang, Weijin
He, Teng
Chen, Ping
Dornheim, Martin
Organisational unit
Publisher
MDPI
Series or journal
Energies
ISSN
Periodical volume
12
Periodical issue
14
Article ID
2779
Part of the university bibliography
✅
Language
English
Keyword
Bimetallic amide
Hydrogen storage
Amide-hydrides
In situ X-ray diffraction
Activation energy
Reaction rate
Abstract
In this work, we investigated the influence of the K₂Mn(NH₂)₄ additive on the hydrogen sorption properties of the Mg(NH₂)₂ + 2LiH (Li–Mg–N–H) system. The addition of 5 mol% of K₂Mn(NH₂)₄ to the Li–Mg–N–H system leads to a decrease of the dehydrogenation peak temperature from 200°C to 172°C compared to the pristine sample. This sample exhibits a constant hydrogen storage capacity of 4.2 wt.% over 25 dehydrogenation/rehydrogenation cycles. Besides that, the in-situ synchrotron powder X-ray diffraction analysis performed on the as prepared Mg(NH₂)₂ + 2LiH containing K₂Mn(NH₂)₄ indicates the presence of Mn₄N. However, no crystalline K-containing phases were detected. Upon dehydrogenation, the formation of KH is observed. The presence of KH and Mn₄N positively influences the hydrogen sorption properties of this system, especially at the later stage of rehydrogenation. Under the applied conditions, hydrogenation of the last 1 wt.% takes place in only 2 min. This feature is preserved in the following three cycles.
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This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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