Resolving the stability and structure of strontium chloride amines from equilibrium pressures, XRD and DFT

Publication: Research - peer-reviewJournal article – Annual report year: 2012

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Resolving the stability and structure of strontium chloride amines from equilibrium pressures, XRD and DFT. / Lysgaard, Steen; Ammitzbøll, Andreas L. ; Johnsen, Rune; Norby, Poul; Quaade, Ulrich J.; Vegge, Tejs.

In: International Journal of Hydrogen Energy, Vol. 37, No. 24, 2012, p. 18927-18936.

Publication: Research - peer-reviewJournal article – Annual report year: 2012

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Lysgaard, Steen; Ammitzbøll, Andreas L. ; Johnsen, Rune; Norby, Poul; Quaade, Ulrich J.; Vegge, Tejs / Resolving the stability and structure of strontium chloride amines from equilibrium pressures, XRD and DFT.

In: International Journal of Hydrogen Energy, Vol. 37, No. 24, 2012, p. 18927-18936.

Publication: Research - peer-reviewJournal article – Annual report year: 2012

Bibtex

@article{c67768e3c1194506a82cd83b9f10116c,
title = "Resolving the stability and structure of strontium chloride amines from equilibrium pressures, XRD and DFT",
keywords = "Indirect hydrogen storage, Metal halide amines, Ammonia, Structural characterization, Density functional theory",
publisher = "Pergamon",
author = "Steen Lysgaard and Ammitzbøll, {Andreas L.} and Rune Johnsen and Poul Norby and Quaade, {Ulrich J.} and Tejs Vegge",
year = "2012",
doi = "10.1016/j.ijhydene.2012.09.129",
volume = "37",
number = "24",
pages = "18927--18936",
journal = "International Journal of Hydrogen Energy",
issn = "0360-3199",

}

RIS

TY - JOUR

T1 - Resolving the stability and structure of strontium chloride amines from equilibrium pressures, XRD and DFT

A1 - Lysgaard,Steen

A1 - Ammitzbøll, Andreas L.

A1 - Johnsen,Rune

A1 - Norby,Poul

A1 - Quaade,Ulrich J.

A1 - Vegge,Tejs

AU - Lysgaard,Steen

AU - Ammitzbøll, Andreas L.

AU - Johnsen,Rune

AU - Norby,Poul

AU - Quaade,Ulrich J.

AU - Vegge,Tejs

PB - Pergamon

PY - 2012

Y1 - 2012

N2 - Strontium chloride octamine, Sr(NH3)8Cl2, has been shown to be a highly efficient ammonia reservoir for selective catalytic reduction of NOx gases in vehicle exhaust and to hold great potential for indirect hydrogen storage. The possible applications of such metal amines depend explicitly on the conditions for ammonia release and it is thus essential to understand the exact ab- and desorption mechanisms. Here, we apply equilibrium pressure measurements from ammonia desorption, X-ray powder diffraction and density functional theory calculations to identify thermodynamically stable Sr(NH3)Cl2, Sr(NH3)2Cl2 and Sr(NH3)8Cl2 phases. The crystal structures were solved in the space groups Cmcm, Aem2 and Pnma respectively. Controversy regarding the possible existence of a diamine phase is resolved on the basis of a combined structural and thermodynamic analysis of the ammonia release mechanisms, yielding a diamine structure with nearly the same stability as the monoamine. Depending on temperature and pressure, the diamine phase is found to have marginally higher or lower stability than the monoamine phase which explains why the diamine phase is found in some experiments and is not found in others.

AB - Strontium chloride octamine, Sr(NH3)8Cl2, has been shown to be a highly efficient ammonia reservoir for selective catalytic reduction of NOx gases in vehicle exhaust and to hold great potential for indirect hydrogen storage. The possible applications of such metal amines depend explicitly on the conditions for ammonia release and it is thus essential to understand the exact ab- and desorption mechanisms. Here, we apply equilibrium pressure measurements from ammonia desorption, X-ray powder diffraction and density functional theory calculations to identify thermodynamically stable Sr(NH3)Cl2, Sr(NH3)2Cl2 and Sr(NH3)8Cl2 phases. The crystal structures were solved in the space groups Cmcm, Aem2 and Pnma respectively. Controversy regarding the possible existence of a diamine phase is resolved on the basis of a combined structural and thermodynamic analysis of the ammonia release mechanisms, yielding a diamine structure with nearly the same stability as the monoamine. Depending on temperature and pressure, the diamine phase is found to have marginally higher or lower stability than the monoamine phase which explains why the diamine phase is found in some experiments and is not found in others.

KW - Indirect hydrogen storage

KW - Metal halide amines

KW - Ammonia

KW - Structural characterization

KW - Density functional theory

U2 - 10.1016/j.ijhydene.2012.09.129

DO - 10.1016/j.ijhydene.2012.09.129

JO - International Journal of Hydrogen Energy

JF - International Journal of Hydrogen Energy

SN - 0360-3199

IS - 24

VL - 37

SP - 18927

EP - 18936

ER -