Kinetics of high temperature, hydrocarbon assisted boron combustion

Brown, Robert C.; Kolb, C. E.; Cho, S.Y.; Yetter, Richard A.; Rabitz, H.; Dryer, Frederick L.

doi:10.1016/b978-0-444-89070-2.50030-x

Cited by 2 publications

(2 citation statements)

References 17 publications

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“…When hydrogen is present, a substantial amount of boron gets trapped as metastable species such as HBO and HOBO, with less energy release than would occur with formation of B 2 O 3 . Because of these problems, extensive efforts are underway to create quantitative models for the complex processes of boron ignition and combustion and to study the detailed kinetics of homogeneous gas-phase − , and heterogeneous boron combustion. , These modeling studies require first of all thermodynamic and kinetic data, including heats of reactions and activation barriers. − Accurate ab initio and density functional calculations of potential energy surfaces (PES) for the reactions involved in boron combustion are a valuable tool to achieve these data.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study of the Reaction Mechanism of BO, B₂O₂, and BS with H₂

2003

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Potential energy surfaces of various reactions in the BO/H2, B2O2/H2, and BS/H2 systems have been studied at the G2M(MP2)//B3LYP/6-311+G(d,p) level of theory. The BO + H2 reaction is shown to proceed by abstraction of a hydrogen atom by B to produce OBH + H with the barrier and exothermicity of 8.3 and 6.8 kcal/mol, respectively. The reaction can also occur by 1,2-insertion of BO into the H−H bond or by H abstraction by the O atom; however, the barriers for these channels are much higher, 36.4 and 42.7 kcal/mol, respectively. Via a low ∼0.3 kcal/mol barrier, the OBH + H reaction produces the OBH2 radical, which is the most stable compound in the BO/H2 system and lies 15.9, 2.5, and 4.2 kcal/mol below BO + H2, trans-HBOH, and cis-HBOH, respectively. OBH2 can isomerize to trans-HBOH overcoming a barrier of 27.7 kcal/mol and the latter can rearrange to the cis conformer with a barrier of 10.8 kcal/mol. BOH and H can recombine and form cis- or trans-HBOH without barriers. In the B + H2O reaction, the reactants can first form a weakly bound B−H2O complex, which then can eliminate an H atom producing BOH + H or undergo insertion of B into an O−H bond giving trans-HBOH with barriers of 4.7 and 6.2 kcal/mol relative to the initial reactants, respectively, and trans-HBOH can eventually decompose to OBH + H and a minor amount of BO + H2. Singlet OBBO is shown to be much less reactive with respect to H2 than the BO monomer. Alternatively, after two BO recombine to form a triplet OBBO molecule over a moderate 8.3 kcal/mol barrier, t-OBBO can easily react with H2 producing either BO + OBH2 (via a t-OBBH2O intermediate) or OBBOH + H with barriers of 4.4 and 7.4 kcal/mol, respectively. The reactions in the BS/H2 system are shown to be similar to those for BO/H2, except that BS cannot insert into H2, SBH2 resides in a much deeper potential well (37.3 kcal/mol below BS + H2) and can rearrange both to trans- and cis-HBSH, the B−H2S complex is more strongly bound than B−H2O, and the B + H2S reaction is expected to be significantly faster than the reaction of B + H2O.

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Section: Introductionmentioning

confidence: 99%

Theoretical Study of the Reaction Mechanism of BO, B₂O₂, and BS with H₂

2003

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“…The use of Be in fuel applications is impractical due to the acute toxicity of Be and its oxide . And finally, although B and its oxide are relatively innocuous in terms of toxicity, and both the gravimetric and volumetric energy contents of B are superlative, significant problems with B combustion due to the physical properties of B and its oxide have plagued researchers for decades …”

Section: Introductionmentioning

confidence: 99%

Optimization of a High-Energy Ti–Al–B Nanopowder Fuel

et al. 2017

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Sonochemically generated reactive metal nanopowders containing Ti, Al, and B represent a new class of high-energy-density nanopowder fuels with superior energy content and air stability as compared to nano-aluminum. In this work, we optimize the energy density of a Ti–Al–B reactive metal nanopowder fuel by varying the Ti:Al:B ratios using a sonochemically mediated decomposition of a complex metal-hydride. After heating the recovered solids under vacuum to temperatures in the range between 150 to 300 °C, the powder’s air stability is significantly improved so that it can be handled in air. Variable-temperature vacuum heat treatment was used to produce fuels tuned to be stable with a gravimetric energy density exceeding that of pure bulk Al (>31 kJ/g). The density of the powder was found to be 2.62 g/cm3 by helium pycnometry, which translates to an impressive volumetric energy content of 89 kJ/cm3. In poly(methyl methacrylate)-protected bomb calorimetry tests commercial nano-aluminum (SkySpring Nanomaterials, 20% oxide) only produced 25 kJ/g, while the sonochemically generated Ti–Al–B nanopowders released 24% more energy per unit mass and 19% more energy per unit volume in identical experiments.

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Kinetics of high temperature, hydrocarbon assisted boron combustion

Cited by 2 publications

References 17 publications

Theoretical Study of the Reaction Mechanism of BO, B₂O₂, and BS with H₂

Theoretical Study of the Reaction Mechanism of BO, B₂O₂, and BS with H₂

Optimization of a High-Energy Ti–Al–B Nanopowder Fuel

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Kinetics of high temperature, hydrocarbon assisted boron combustion

Cited by 2 publications

References 17 publications

Theoretical Study of the Reaction Mechanism of BO, B2O2, and BS with H2

Theoretical Study of the Reaction Mechanism of BO, B2O2, and BS with H2

Optimization of a High-Energy Ti–Al–B Nanopowder Fuel

Contact Info

Product

Resources

About

Theoretical Study of the Reaction Mechanism of BO, B₂O₂, and BS with H₂

Theoretical Study of the Reaction Mechanism of BO, B₂O₂, and BS with H₂