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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2010

Energy efficient synthesis of boranes

The reaction of halo-boron compounds (B--X compounds, compounds having one or more boron-halogen bonds) with silanes provides boranes (B--H compounds, compounds having one or more B--H bonds) and halosilanes. Inorganic hydrides, such as surface-bound silane hydrides (Si--H) react with B--X compounds to form B--H compounds and surface-bound halosilanes. The surface bound halosilanes are converted back to surface-bound silanes electrochemically. Halo-boron compounds react with stannanes (tin compounds having a Sn--H bond) to form boranes and halostannanes (tin compounds having a Sn--X bond). The halostannanes are converted back to stannanes electrochemically or by the thermolysis of Sn-formate compounds. When the halo-boron compound is BCl.sub.3, the B--H compound is B.sub.2H.sub.6, and where the reducing potential is provided electrochemically or by the thermolysis of formate.

Thorn, David L↗
DOE OSTI2012

Energy efficient synthesis of boranes

The reaction of halo-boron compounds (B--X compounds, compounds having one or more boron-halogen bonds) with silanes provides boranes (B--H compounds, compounds having one or more B--H bonds) and halosilanes. Inorganic hydrides, such as surface-bound silane hydrides (Si--H) react with B--X compounds to form B--H compounds and surface-bound halosilanes. The surface bound halosilanes are converted back to surface-bound silanes electrochemically. Halo-boron compounds react with stannanes (tin compounds having a Sn--H bond) to form boranes and halostannanes (tin compounds having a Sn--X bond). The halostannanes are converted back to stannanes electrochemically or by the thermolysis of Sn-formate compounds. When the halo-boron compound is BCl.sub.3, the B--H compound is B.sub.2H.sub.6, and where the reducing potential is provided electrochemically or by the thermolysis of formate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Method for releasing hydrogen from ammonia borane

A method of releasing hydrogen from ammonia borane is disclosed. The method comprises heating an aqueous ammonia borane solution to between about 80-135.degree. C. at between about 14.7 and 200 pounds per square inch absolute (psia) to release hydrogen by hydrothermolysis.

08 HYDROGEN↗
DOE OSTI2013

Regeneration of ammonia borane from polyborazylene

Method of producing ammonia borane, comprising providing a reagent comprising a dehydrogenated material in a suitable solvent; and combining the reagent with a reducing agent comprising hydrazine, a hydrazine derivative, or combinations thereof, in a reaction which produces a mixture comprising ammonia borane.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Procedures for the synthesis of ethylenediamine bisborane and ammonia borane

A method for synthesizing ammonia borane includes (a) preparing a reaction mixture in one or more solvents, the reaction mixture containing sodium borohydride, at least one ammonium salt, and ammonia; and (b) incubating the reaction mixture at temperatures between about 0.degree. C. to about room temperature in an ambient air environment under conditions sufficient to form ammonia borane. Methods for synthesizing ethylenediamine bisborane, and methods for dehydrogenation of ethylenediamine bisborane are also described.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2010

Dynamic Modeling and Simulation Based Analysis of an Ammonia Borane (AB) Reactor System for Hydrogen Storage

Research on ammonia borane (AB, NH3BH3) has shown it to be a promising material for chemical hydrogen storage in PEM fuel cell applications. AB was selected by DOE’s Hydrogen Storage Engineering Center of Excellence (HSECoE) as the initial chemical hydride of study because of its high hydrogen storage capacity (up to 19.6% by weight for the release of three molar equivalents of hydrogen gas) and its stability under typical ambient conditions. A model of a bead reactor system which includes feed and product tanks, hot and cold augers, a ballast tank/reactor, a H2 burner and a radiator was developed to study AB system performance in an automotive application and estimate the energy, mass, and volume requirements for this off-board regenerable hydrogen storage material. Preliminary system simulation results for a start-up case and for a transient drive cycle indicate appropriate trends in the reactor system dynamics. A new controller was developed and validated in simulation for a couple of H2 demand cases.

08 HYDROGEN↗
DOE OSTI2010

SYSTEMS MODELING OF AMMONIA BORANE BEAD REACTOR FOR OFF-BOARD REGENERABLE HYDROGEN STORAGE IN PEM FUEL CELL APPLICATIONS

Out of the materials available for chemical hydrogen storage in PEM fuel cell applications, ammonia borane (AB, NH3BH3) has a high hydrogen storage capacity (upto 19.6% by weight for the release of three hydrogen molecules). Therefore, AB was chosen in our chemical hydride simulation studies. A model for the AB bead reactor system was developed to study the system performance and determine the energy, mass and volume requirements for off-board regenerable hydrogen storage. The system includes hot and cold augers, ballast tank and reactor, product tank, H2 burner and a radiator. One dimensional models based on conservation of mass, species and energy were used to predict important state variables such as reactant and product concentrations, temperatures of various components, flow rates, along with pressure in the reactor system. Control signals to various components are governed by a control system which is modeled as an independent subsystem. Various subsystem components in the models were coded as C language S-functions and implemented in Matlab/Simulink environment. Preliminary system simulation results for a start-up case and for a transient drive cycle indicate accurate trends in the reactor system dynamics.

08 HYDROGEN↗
DOE OSTI2010

An Investigation of the Structural Phase Transition of Ammonia Borane

A detailed anelastic spectroscopy study of the structural phase transition of ammonia borane was conducted for the first time. The transformation from the tetragonal high temperature phase into the orthorhombic low temperature one is detected on cooling around 220K by a huge drop of the elastic modulus and a spike of the elastic energy dissipation.We find clear indications of a hysteresis, which led us to conclude that the transition is of first-order. The kinetics of the transitionwas investigated in detail. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

36 MATERIALS SCIENCE↗
DOE OSTI2010

Growth of Crystalline Polyaminoborane through Catalytic Dehydrogenation of Ammonia Borane on FeB Nanoalloy

Tremendous effort has been devoted to the study of complex and chemical hydrides for hydrogen storage in the past decade [1, 2] . Ammonia Borane (NH 3 BH 3 , AB) with a hydrogen content of 19.6 wt % has received significant attention [3-5] . Methods to improve the kinetics of the step-wise dehydrogenation of AB are diverse including the uses of mesoporous frameworks [6] , catalysts [7-16] , and additives [17] . It was reported that when dissolving in organic solvents AB released hydrogen readily in the presence of transition metal catalysts through the formation of M∙∙∙HBH 2 NH 3 complex (where M is Ir, Ru, or Ni etc.) [8-10] ; Lewis or Brønsted acids, on the other hand, react with AB in solution to form the initiating species (BH 2 NH 3 ) + [11] , which may have the similar function as the [BH 2 (NH 3 ) 2 ] + BH 4 - (DADB) in the dehydrogenation of solid AB [17, 18] . However, comparatively little study has been reported on the catalytic dehydrogenation of AB in solid form. Other important but less investigated aspects in the solid-state reaction are the characterizations of functional catalytic species and products from the step-wise dehydrogenation.

08 HYDROGEN↗
DOE OSTI2012

Quantifying the thermodynamic interactions of polyhedral boranes in solution to guide nanocomposite fabrication

The solubility of boron containing nanoparticles in a variety of solvents is quantified using static light scattering in conjunction with refractometry. Four polyhedral boranes were tested in this work, using refractometry to obtain dn/dc, while static light scattering quantifies A2. A2 obtained from these measurements was then used to calculate v, the solute solvent interaction parameter, and the ildebrand solubility parameter, d, which provides a quantifiable method to identify good solvents. Of the nanoparticles studied, 1,3-di-o-carboranylpropane is thermodynamically stable in toluene, with a v less than 0.5, a solubility limit of 2.47 mg/mL, and all solutions remaining clear with no visible particle settling. For all of the particles tested, there was good correlation between the physical observations of the solutions, v, and d. For instance, lower values of v correspond to a smaller radius of gyration (Rg). A list of suitable solvents based on d is also presented.

boranes↗
DOE OSTI2019

Mercury derivatives of polyhedral boranes, carboranes, and metallacarboranes

The review concerns the synthesis, structure, and chemical transformations of mercury derivatives of various polyhedral boron hydrides (carboranes, metallacarboranes, and boranes) and covers a period of time since the pioneering studies of Prof. V. I. Bregadze on chemistry of C- and B-substituted derivatives of icosahedral carboranes C{sub 2}B{sub 10}H{sub 12} up to date. The emphasis is placed on recent results obtained in this field, in particular, Hg-promoted substitution in nido-carboranes as well as the synthesis and properties of mercury derivatives of monocarbon carborane anion [CB{sub 11}H{sub 12}]{sup –}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Chitosan supported palladium nanoparticles: The novel catalysts for hydrogen generation from hydrolysis of ammonia borane

Highlights: • Chitosan is used to anchor the in-situ reduced ultrafine palladium nanoparticles. • The Pd NPs/CS catalysts display superior catalytic behavior for H{sub 2} generation from AB. • The reaction kinetics over the catalysts is also studied in details. - Abstract: Chitosan supported palladium nanoparticles (Pd NPs/CS) catalysts were facilely prepared via an in-situ reduction of PdCl{sub 2} method and characterized by various techniques. The results showed that the palladium particles were in the range of 4–8 nm and evenly dispersed on chitosan. Furthermore, the resulting Pd NPs/CS catalysts showed high catalytic activity for the hydrolytic dehydrogenation of ammonia borane (NH{sub 3}BH{sub 3}, AB) in aqueous solution. As for the catalytic reaction with an activation energy (E{sub a}) of 36.25 kJ mol{sup −1}, the orders of palladium and AB concentrations were 0.81 and 0.45, respectively. The maximum turnover frequency was as high as 24.76 mol{sub H{sub 2}}·mol{sub Pd}{sup -1}·min{sup -1} at 30 °C. In addition, the Pd NPs/CS catalysts still kept satisfied catalytic activity even after eleven runs.

08 HYDROGEN↗
DOE OSTI2017

Catalytic Dehydrogenation of Dimethylamine Borane by Highly Active Thorium and Uranium Metallocene Complexes

In the thorium and uranium complexes (C 5 Me 5 ) 2 AnMe 2 , [(C 5 Me 5 ) 2 An(H)(μ-H)] 2 (An = Th, U) and [(C 5 Me 5 ) 2 U(H)] 2 dehydrogenate dimethylamine borane (Me2NH·BH3) at room temperature. Upon mild heating at 45 °C, turnover frequencies (TOFs) of 400 h –1 are obtained, which is comparable to some of the fastest Me 2 NH·BH 3 dehydrogenation catalysts known in the literature. We propose a β-hydride elimination mechanism for dehydrogenation because of the observation of Me 2 N=BH 2 , Me 2 N=BMe 2 , and Me 2 N=BHMe in the 11 B NMR spectra of catalytic and stoichiometric reactions. The similar catalytic metrics between the actinide dimethyl and hydride complexes with Me 2 NH·BH 3 indicate that the actinide hydride complexes are the active catalysts in this chemistry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Experimental and Theoretical Studies on a High Pressure Monoclinic Phase of Ammonia Borane

The effect of pressure on the structure of ammonia borane NH{sub 3}BH{sub 3} (AB) was investigated using a combination of high pressure X-ray diffraction (XRD) and density functional theory (DFT). In situ XRD was performed up to 15.0 GPa at room temperature in a diamond anvil cell, and two first-order phase transitions were observed at 1.6 and 12.9 GPa. The ambient pressure I4mm structure transformed into the high pressure Cmc2{sub 1} phase at 1.6 GPa, and then experienced a second-order isostructural phase transition at 5 GPa, and further developed into a monoclinic P2{sub 1} (Z = 4) phase at 12.9 GPa. The structure of the high pressure P2{sub 1} phase was solved by powder diffraction data and further optimized using DFT calculations. The high pressure phase transitions were found to be reversible upon releasing pressure. The behavior of the N-H {hor_ellipsis} H-B dihydrogen bonding framework, inter- and intramolecular interactions at high pressure was also investigated. The origin of the phase transition at 12.9 GPa is attributed to the reorganization of the dihydrogen bonding network and the change in the rotational dynamics of the NH{sub 3} and BH{sub 3} groups.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Understanding Vibrational Anharmonicity and Phonon Dispersion in Solid Ammonia Borane

We compute the hydrogen vibrational spectra for bulk ammonia borane (NH3BH3) using harmonic and anharmonic methodologies as well as quantifying dispersive effects to determine their influence on the resulting spectra. Even at 10K the accounting of anharmonic effects on the IINS signal are more significant than approximations introduced by sampling and interpolating a finite simulation cell to capture dispersion effects. We compare our computed anharmonic power spectrum with IINS spectral measurements and find excellent agreement. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences and Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

08 HYDROGEN↗
DOE OSTI2010

Characterization of a New Phase of Ammonia Borane

An uncharacterized phase of ammonia borane (AB) was previously identified while investigating its thermal decomposition. This phase was identified as a key intermediate for the release of hydrogen from AB prompting the current characterization study. The new phase was investigated extensively using in situ solid state MAS NMR spectroscopy, including 11B, 15N and 1H NMR. Single-pulse excitation, cross polarization and T1 relaxation experiments collectively demonstrate a significant increase in mobility for the new phase when compared to the room temperature crystalline phase of AB. However, the data are not completely consistent with a liquid phase. The data are also not consistent with a solid phase, but are most consistent with a phase best described as “liquid-like”. This implies a disruption of the long-range order which is primarily stabilized by the extensive dihydrogen bonding network, allowing increased motional freedom. X-ray diffraction and Raman thermal decomposition data of neat AB provide support for a disordered phase, as does data of AB immobilized into a mesoporous scaffold. These observations suggest that a breakdown of the extensive hydrogen bonding network is necessary before hydrogen can be released and will be an important factor in the practical use of AB as a hydrogen storage material. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

08 HYDROGEN↗
DOE OSTI2014

Kinetics Study of Solid Ammonia Borane Hydrogen Release – Modeling and Experimental Validation for Chemical Hydrogen Storage

Ammonia borane (AB), NH3BH3, is a promising material for chemical hydrogen storage with 19.6 wt% gravimetric hydrogen capacity of which 16.2 wt% hydrogen can be utilized below 200°C. We have investigated the kinetics of hydrogen release from AB and from an AB-methyl cellulose (AB/MC) composite at temperatures of 160-300°C using both experiments and modeling. The purpose of our study was to show safe hydrogen release without thermal runaway effects and to validate system model kinetics. AB/MC released hydrogen at ~20°C lower than neat AB and at a rate that is two times faster. Based on the experimental results, the kinetics equations were revised to better represent the growth and nucleation process during decomposition of AB. We explored two different reactor concepts; Auger and fixed bed. The current Auger reactor concept turned out to not be appropriate, however, we demonstrated safe self-propagation of the hydrogen release reaction of solid AB/MC in a fixed bed reactor.

ammonia borane↗