The thermal dissociation of NH3BH3

Sit, V.; Geanangel, R. A.; Wendlandt, W.W.

doi:10.1016/0040-6031(87)88340-5

Cited by 179 publications

(122 citation statements)

References 4 publications

Supporting

Mentioning

118

Contrasting

Unclassified

Order By: Relevance

“…In Ca(NH 2 BH 3 ) 2 ·NH 3 , the Ca 2+ cation has a trigonal bipyramidal coordination geometry, surrounded by two N's of the NH 2 As a result of the Ca−N interaction, the N−H bonds in the adducted NH 3 were lengthened (1.025 Å versus 1.020 Å in NH 3 gas). This is further evidenced by the absences of the high-frequency N−H stretching of NH 3 (∼3444 cm 28−30 were also detected in Ca(NH 2 BH 3 ) 2 ·NH 3 , revealing a strengthened B−N bond and weakened B−H bond, respectively, in the structure.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The shortest dihydrogen bond was identified to originate from the intermolecular interaction between coordinated NH 3 and the BH 3 of NH 2 BH 3 − of the adjacent molecule. Figure 4 shows the neutron vibrational spectra of Ca-(NH 2 . 23 The TG-DSC results shown in Figure 6 also indicated an endothermic reaction in the first-step deammoniation process with a significant weight loss of 12.6 mass % [or 0.87 equivalents/formula unit of NH 3 ].…”

Section: ···Hmentioning

confidence: 99%

“…However, its widespread application is restricted because of the slow dehydrogenation kinetics and the release of volatile byproduct. 1,2 Aiming to improve its hydrogen storage properties, active research activities have been focused on the catalytic dehydrocoupling of ammonia borane and its derivatives, that is, primary and secondary amineboranes (RNH 2 BH 3 and R 2 NHBH 3 ). 3−6 Besides kinetic improvement, ammonia borane with its potential N−H group which protonic H + is of the weak Lewis acidity, could be functionalized for thermodynamic improvement.…”

Section: ■ Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Monoammoniate of Calcium Amidoborane: Synthesis, Structure, and Hydrogen-Storage Properties

Chua

Zhou

et al. 2012

Inorg. Chem.

View full text Add to dashboard Cite

The monoammoniate of calcium amidoborane, Ca-(NH 2 BH 3 ) 2 ·NH 3 , was synthesized by ball milling an equimolar mixture of CaNH and AB. Its crystal structure has been determined and was found to contain a dihydrogen-bonded network. Thermal decomposition under an open-system begins with the evolution of about 1 equivalent/formula unit (equiv.) of NH 3 at temperatures <100°C followed by the decomposition of Ca(NH 2 BH 3 ) 2 to release hydrogen. In a closed-system thermal decomposition process, hydrogen is liberated in two stages, at about 70 and 180°C, with the first stage corresponding to an exothermic process. It has been found that the presence of the coordinated NH 3 has induced the dehydrogenation to occur at low temperature. At the end of the dehydrogenation, about 6 equiv. (∼ 10.2 wt %) of hydrogen can be released, giving rise to the formation of CaB 2 N 3 H. ■ INTRODUCTIONThe increasing scarcity of fossil fuels and their link to global warming underscores the need to shift our current energy sources to more environmentally friendly and efficient alternatives. Hydrogen has been regarded as the most promising future fuel as it is high in energy and when it burns, it produces no pollution. However, one of the most important technological challenges facing a hydrogen economy is the development of safe and energy-efficient hydrogenstorage materials, especially for use with hydrogen fuel-cell vehicles. Ammonia borane (NH 3 BH 3 , AB) has drawn significant attention as one of the potential hydrogen-storage materials because of its high hydrogen capacity (ca. 19.6 wt %) and moderate dehydrogenation properties. However, its widespread application is restricted because of the slow dehydrogenation kinetics and the release of volatile byproduct.1,2 Aiming to improve its hydrogen storage properties, active research activities have been focused on the catalytic dehydrocoupling of ammonia borane and its derivatives, that is, primary and secondary amineboranes (RNH 2 BH 3 and R 2 NHBH 3 ).3−6 Besides kinetic improvement, ammonia borane with its potential N−H group which protonic H + is of the weak Lewis acidity, could be functionalized for thermodynamic improvement. As results of the introduction of a functional group by reacting ammonia borane with a stronger Lewis acid, that is, metal hydrides, a series of single-metal and double-metal amidoboranes consisting of metal cations and amidoborane anions were developed, including amidoboranes of Li,7,8 Na,7 K, 9 Ca, 10,11 Sr, 12 Y, 13 Na 2 Mg, 14 NaMg, 15 and NaLi. 16 These metal amidoboranes are found to exhibit significant improvement over the parent AB, including reduced dehydrogenation temperature with moderate dehydrogenation thermodynamics, improved dehydrogenation kinetics, and suppression of the release of volatile byproduct. In addition, intensive mechanistic investigations were also studied to understand the role of metal cation in the improved dehydrogenation properties. 3,17−21 Besides metal hydrides, metal amides or imides, which typically contain s...

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ···Hmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Monoammoniate of Calcium Amidoborane: Synthesis, Structure, and Hydrogen-Storage Properties

Chua

Zhou

et al. 2012

Inorg. Chem.

View full text Add to dashboard Cite

show abstract

“…Thermal dehydrogenation of AB takes place in three distinct steps within a broad temperature range and giving one equivalent of H 2 at each step [33,34]. However, releasing the last equivalent of H 2 can only be achieved at temperatures above 500°C; thus, only the first two steps are considered for producing ''usable'' hydrogen.…”

Section: Ammonia Boranementioning

confidence: 99%

Thermodynamics study of hydrogen storage materials

Song

Wang

Jiao

et al. 2012

The Journal of Chemical Thermodynamics

View full text Add to dashboard Cite

“…The dehydrogenation of B-N-H containing chemical hydride systems is a process involving the dissociation and combination of hydridic H(B) and protic H(N) atoms, [56][57][58][59] and the initiation of dehydrogenation needs to overcome a kinetic barrier, which is related to the energy cost for the breaking of B-H and N-H bonds, as well as the energy barrier for the combination of H(B) and H(N) to form H 2 . Thus the kinetic aspect of the dehydrogenation may be partially determined by the strength of B-H and N-H bonds, and interaction between the H(B) and H(N) atoms.…”

Section: Hydrogen Atom Removal Energymentioning

confidence: 99%