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Main Title: Mayenite-Based Electride C12A7e−: A Reactivity and Stability Study
Author(s): Weber, Sebastian
Schäfer, Sebastian
Saccoccio, Mattia
Ortner, Nils
Bertmer, Marko
Seidel, Karsten
Berendts, Stefan
Lerch, Martin
Gläser, Roger
Kohlmann, Holger
Schunk, Stephan A.
Type: Article
Language Code: en
Abstract: Ru supported on mayenite electride, [Ca24Al28O64]4+(e−)4 a calcium aluminum oxide denoted as C12A7e−, are described in the literature as highly active catalysts for ammonia synthesis, especially under conditions of low absolute pressure. In this study, we investigated the application of recently reported plasma arc melting synthesized C12A7e− (aluminum solid reductant) as supports of Ru/C12A7e− catalysts in ammonia synthesis up to pressures of 7.6 MPa. Together with the plasma-arc-melting-based catalyst support, we investigated a similar plasma-synthesized C12A7e− (graphite solid reductant) and a vacuum-sintering-based C12A7e−. Complementary to the catalytic tests, we applied 2H solid-state NMR spectroscopy, DRUVVis-spectroscopy, thermal analysis and PXRD to study and characterize the reactivity of different plasma-synthesized and vacuum-sintered C12A7e− towards H2/D2 and H2O. The catalysts showed an immediate deactivation at pressures > 1 MPa, which can be explained by irreversible hydride formation at higher pressures, as revealed by reactivity tests of C12A7e− towards H2/D2. The direct formation of C12A7:D from C12A7e− is proven. It can be concluded that the application of Ru/C12A7e− catalysts at the industrial scale has limited prospects due to irreversible hydride formation at relevant pressures > 1 MPa. Furthermore, we report an in-depth study relating to structural changes in the material in the presence of H2O.
Issue Date: 5-Mar-2021
Date Available: 9-Apr-2021
DDC Class: 540 Chemie und zugeordnete Wissenschaften
Subject(s): mayenite
calcium aluminates
catalyst support
ammonia synthesis
catalyst deactivation
hydride ions
Journal Title: Catalysts
Publisher: MDPI
Publisher Place: Basel
Volume: 11
Issue: 3
Article Number: 334
Publisher DOI: 10.3390/catal11030334
EISSN: 2073-4344
Appears in Collections:FG Festkörperchemie » Publications

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