Experimental and Theoretical Investigations on the
Chemistry and Dynamics of Ammonia Borane Dehydrogenation
EMSL Project ID
25661
Abstract
Increasing demands for clean energy sources that do not add CO2 and other pollutants to the environment have resulted in increased worldwide interest in the possibilities of a "hydrogen economy" as a long-term solution for a secure energy future based on potentially renewable resources. Some of the greatest challenges are the discovery and development of new on-board hydrogen storage materials and catalysts for fuel cell powered vehicles. New materials that store both high gravimetric and high volumetric densities of hydrogen that release H2 at temperatures <100 °C and uptake H2 at pressures < 10 bar are highly desired. The volumetric constraints eliminate from consideration pressurized hydrogen systems and guide towards the development of solid storage materials. There are no currently known materials that meet these requirements. As such, there is a need for fundamental understanding of the chemical and physical properties of hydrogen rich materials (HRM). Specifically, what molecular attributes facilitate the release and uptake of molecular hydrogen chemisorbed to light weight elements. We hypothesize that efficient storage of hydrogen might be accomplished in compounds that have alternating electron rich and electron deficient sites capable of covalently binding H+ and H-, respectively. These properties are exemplified by ammonia borane (AB = NH3BH3). This project utilizes an integrated experimental and computational approach to elucidate the molecular-level structural, chemical and physical properties of AB that results in the release and uptake of molecular hydrogen. Our research on AB has two main objectives: a molecular description of the evolution of H2 from AB and development of a fundamental description of the proton dynamics of AB. We have used EMSL resources to conduct experiments at the macroscopic level to determine the thermodynamics and kinetics of hydrogen release and used molecular level probes such as NMR and Raman spectroscopy to identify intermediates and decomposition products. These experiments have provided the basis for our computational studies which have identified potential reaction pathways and reaction intermediates for H2 release. We have also used EMSL resources to study the proton dynamics as a function of temperature and across the orthorhombic to tetragonal structural phase transition at 225 K. We propose to continue our investigation of AB as hydrogen storage material and extend our investigation to include AB deposited on mesoporous silica scaffold using DSC/TGA, PXRD, NMR, Raman spectroscopy and computational al modeling. The computational research will focus on plane-wave CPMD simulations and molecular DFT computational modeling on the structural, spectroscopic (IR, Raman, NMR, etc.), and chemical properties to provide molecular-level understanding of the interactions and reaction dynamics of the chemical processes involved in hydrogen release. Fundamental understandings will be gained from these theoretical studies, which will provide interpretations of the experimental results and theoretical guidance in designing and optimizing hydrogen storage materials that have optimal thermodynamic and kinetic properties for hydrogen release. Elucidation of the mechanism by which the scaffold impacts H2 release and proton dynamics is key to further "tuning" AB as a potential hydrogen storage material for on-board fuel cell applications.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2007-05-23
End Date
2010-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Hydrogen Storage Properties of New Hydrogen-Rich BH3NH3-Metal Hydride (TiH2, ZrH2, MgH2, and/or CaH2) Composite Systems
Choi YJ, Y Xu, WJ Shaw, and E Ronnebro. 2012. "Hydrogen Storage Properties of New Hydrogen-Rich BH3NH3-Metal Hydride (TiH2, ZrH2, MgH2, and/or CaH2) Composite Systems." Journal of Physical Chemistry C C116(15):8349-8358. doi:10.1021/jp210460w
Synthesis and Characterization of Methylammonium Borohydride
Graham KR, ME Bowden, and T Kemmitt. 2011. "Synthesis and Characterization of Methylammonium Borohydride." Inorganic Chemistry 50(3):932-936. doi:10.1021/ic1015719
Experimental and computational studies on collective hydrogen dynamics in ammonia borane: Incoherent inelastic neutron scattering
Kathmann SM, VM Parvanov, GK Schenter, AC Stowe, LL Daemen, MA Hartl, JC Linehan, NJ Hess, AJ Karkamkar, and T Autrey. 2009. "Experimental and Computational Studies on Collective Hydrogen Dynamics in Ammonia Borane: Incoherent Inelastic Neutron Scattering." Journal of Chemical Physics 130(2):article no. 024507. doi:10.1063/1.3042270
Thermochemistry of Lewis Adducts of BH3 and Nucleophilic Substitution of Triethylamine on NH3BH3 in Tetrahydrofuran
Potter RG, DM Camaioni, M Vasiliu, and DA Dixon. 2010. "Thermochemistry of Lewis Adducts of BH3 and Nucleophilic Substitution of Triethylamine on NH3BH3 in Tetrahydrofuran." Inorganic Chemistry 49(22):10512-10521. doi:10.1021/ic101481c
Reversible dehydrogenation of magnesium borohydride to magnesium triborane in the solid state under moderate conditions
Chong M, AJ Karkamkar, T Autrey, S Orimo, S Jalisatgi, and CM Jensen. 2010. "Reversible Dehydrogenation of Magnesium Borohydride to Magnesium Triborane in the Solid State Under Moderate Conditions." PNNL-SA-74978, Pacific Northwest National Laboratory, Richland, WA. doi:10.1039/c0cc03461d
The diammoniate of diborane: crystal structure and hydrogen release
Bowden ME, DJ Heldebrant, AJ Karkamkar, TE Proffen, GK Schenter, and T Autrey. 2010. "The diammoniate of diborane: Crystal structure and hydrogen release." Chemical Communications 46(45):8564-8566. doi:10.1039/C0CC03249B
Neutron Powder Diffraction and Molecular Simulation Study of the Structural Evolution of Ammonia Borane from 15 to 340 K
Hess NJ, GK Schenter, MR Hartman, LL Daemen, TE Proffen, SM Kathmann, CJ Mundy, MA Hartl, DJ Heldebrant, AC Stowe, and T Autrey. 2009. "Neutron Powder Diffraction and Molecular Simulation Study of the Structural Evolution of Ammonia Borane from 15 to 340 K." Journal of Physical Chemistry A 113(9):5723-5735. doi:10.1021/jp900839c
Quasielastic neutron scattering of –NH3 and –BH3 rotational dynamics in orthorhombic ammonia borane
Hess NJ, MR Hartman, C Brown, E Mamontov, AJ Karkamkar, DJ Heldebrant, LL Daemen, and T Autrey. 2008. "Quasielastic neutron scattering of -NH3 and -BH3 rotational dynamics in orthorhombic ammonia borane." Chemical Physics Letters 459(1-6):85-88. doi:10.1016/j.cplett.2008.04.130