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Title: Control of hydrogen release and uptake in amine borane molecular complexes: Thermodynamics of ammonia borane, ammonium borohydride, and the diammoniate of diborane

Abstract

Molecular complexes of Lewis acid-base pairs can be used to activate molecular hydrogen for applications ranging from hydrogen storage for fuel cells to catalytic hydrogenation reactions. In this paper, we examine the factors that determine the thermodynamics of hydrogen activation of a Lewis acid-base pair using the pedagogical examples of ammonia borane (NH3BH3, AB) and ammonium borohydride ([NH4][BH4], ABH2). At ambient temperatures, ABH2 loses hydrogen to form the Lewis acid-base complex AB, suggesting that free energy drives the reaction to release hydrogen. However, direct measurement of the reaction enthalpy is not straightforward given the complex decomposition pathways leading to the formation of the diammoniate of diborane ([NH3BH3NH3][BH4], DADB). In this work, we compare two approaches for deriving the thermodynamic relationships among AB, DADB, and ABH2.

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1028048
Report Number(s):
PNNL-SA-76789
Journal ID: ISSN 1359-6640; 39979; KC0302010; TRN: US201121%%693
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Faraday Discussions
Additional Journal Information:
Journal Volume: 151; Journal ID: ISSN 1359-6640
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; 30 DIRECT ENERGY CONVERSION; AMBIENT TEMPERATURE; AMINES; AMMONIA; BORANES; BOROHYDRIDES; ENTHALPY; FREE ENERGY; FUEL CELLS; HYDROGEN; HYDROGEN STORAGE; HYDROGENATION; THERMODYNAMICS; Environmental Molecular Sciences Laboratory

Citation Formats

Autrey, Thomas, Bowden, Mark E, and Karkamkar, Abhijeet J. Control of hydrogen release and uptake in amine borane molecular complexes: Thermodynamics of ammonia borane, ammonium borohydride, and the diammoniate of diborane. United States: N. p., 2011. Web. doi:10.1039/C0FD00015A.
Autrey, Thomas, Bowden, Mark E, & Karkamkar, Abhijeet J. Control of hydrogen release and uptake in amine borane molecular complexes: Thermodynamics of ammonia borane, ammonium borohydride, and the diammoniate of diborane. United States. doi:10.1039/C0FD00015A.
Autrey, Thomas, Bowden, Mark E, and Karkamkar, Abhijeet J. Mon . "Control of hydrogen release and uptake in amine borane molecular complexes: Thermodynamics of ammonia borane, ammonium borohydride, and the diammoniate of diborane". United States. doi:10.1039/C0FD00015A.
@article{osti_1028048,
title = {Control of hydrogen release and uptake in amine borane molecular complexes: Thermodynamics of ammonia borane, ammonium borohydride, and the diammoniate of diborane},
author = {Autrey, Thomas and Bowden, Mark E and Karkamkar, Abhijeet J},
abstractNote = {Molecular complexes of Lewis acid-base pairs can be used to activate molecular hydrogen for applications ranging from hydrogen storage for fuel cells to catalytic hydrogenation reactions. In this paper, we examine the factors that determine the thermodynamics of hydrogen activation of a Lewis acid-base pair using the pedagogical examples of ammonia borane (NH3BH3, AB) and ammonium borohydride ([NH4][BH4], ABH2). At ambient temperatures, ABH2 loses hydrogen to form the Lewis acid-base complex AB, suggesting that free energy drives the reaction to release hydrogen. However, direct measurement of the reaction enthalpy is not straightforward given the complex decomposition pathways leading to the formation of the diammoniate of diborane ([NH3BH3NH3][BH4], DADB). In this work, we compare two approaches for deriving the thermodynamic relationships among AB, DADB, and ABH2.},
doi = {10.1039/C0FD00015A},
journal = {Faraday Discussions},
issn = {1359-6640},
number = ,
volume = 151,
place = {United States},
year = {2011},
month = {5}
}