Ammonia Decomposition Enhancement by Cs-Promoted Fe/Al2O3 Catalysts
A range of Cs-doped Fe/Al 2 O 3 catalysts were prepared for the ammonia decomposition reaction. Through time on-line studies it was shown that at all loadings of Cs investigated the activity of the Fe/Al 2 O 3 catalysts was enhanced, with the optimum Cs:Fe being ca. 1. Initially, the rate of NH 3 de...
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Published in | Catalysis letters Vol. 150; no. 12; pp. 3369 - 3376 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
New York
Springer US
01.12.2020
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Subjects | |
Online Access | Get full text |
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Summary: | A range of Cs-doped Fe/Al
2
O
3
catalysts were prepared for the ammonia decomposition reaction. Through time on-line studies it was shown that at all loadings of Cs investigated the activity of the Fe/Al
2
O
3
catalysts was enhanced, with the optimum Cs:Fe being ca. 1. Initially, the rate of NH
3
decomposition was low, typically < 10% equilibrium conversion (99.7%@500°C) recorded after 1 h. All catalysts exhibited an induction period (typically ca. 10 h) with the conversion reaching a high of 67% equilibrium conversion for Cs:Fe = 0.5 and 1. The highest rate of decomposition observed was attributed to the balance between increasing the concentration of Cs without blocking the active site. Analysis of H
2
-TPR and XPS measurements indicated that Cs acts as an electronic promoter. Previously, Cs has been shown to act as a promoter for Ru, where Cs alters the electron density of the active site, thereby facilitating the recombination of N
2
which is considered the rate determining step. In addition, XRD and N
2
adsorption measurements suggest that with higher Cs loadings deactivation of the catalytic activity is due to a layer of CsOH that forms on the surface and blocks active sites.
Graphic Abstract |
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ISSN: | 1011-372X 1572-879X |
DOI: | 10.1007/s10562-020-03247-3 |