Quantitative evaluation of catalytic effect of metal chlorides on the decomposition reaction of NaAlH4

Hiroshi Hirate, Yuki Saito, Ippei Nakaya, Hiroshi Sawai, Hiroshi Yukawa, Masahiko Morinaga, Hiromi Nakai

    Research output: Contribution to journalArticle

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    Abstract

    The hydrogen desorption (or decomposition) reaction of NaAlH4 is expressed as NaAlH4 → 1/3 Na3AlH6 + 2/3 Al + H2, and its desorption rate is accelerated by mixing metal chloride catalysts (e.g., TiCl3). This catalytic effect of metal chlorides, MCln, is theoretically estimated in a quantitative way using atomization energy concept. The atomization energies, δEM for metal ion and δECl for chloride ion in various metal chlorides are evaluated using the energy density analysis of the total energy. It is shown that the hydrogen desorption reaction rate increases with increasing n × δEM values of metal chlorides. This indicates that the metal ion in MCln interacts mainly with hydrogen or [AlH 4]- complex anion in NaAlH4. To confirm this calculated result, experiments are performed using NaAlH4 mixed with Ti-based catalysts. The hydrogen desorption rate is enhanced in the order, TiCl3 > TiO2 > Ti metal nanopowder, indicating that the Ti ions in TiCl3 or TiO2 work to promote the catalytic reaction more effectively than the neutral Ti atoms in Ti metal nanopowder.

    Original languageEnglish
    Pages (from-to)950-960
    Number of pages11
    JournalInternational Journal of Quantum Chemistry
    Volume111
    Issue number5
    DOIs
    Publication statusPublished - 2011 Apr

    Fingerprint

    Chlorides
    Metals
    chlorides
    Decomposition
    decomposition
    evaluation
    Hydrogen
    Desorption
    desorption
    metals
    atomizing
    Atomization
    hydrogen
    Metal ions
    metal ions
    Ions
    catalysts
    Catalysts
    neutral atoms
    Reaction rates

    Keywords

    • atomization energy
    • catalytic effect
    • decomposition reaction
    • quantitative evaluation
    • sodium alanate

    ASJC Scopus subject areas

    • Condensed Matter Physics
    • Atomic and Molecular Physics, and Optics
    • Physical and Theoretical Chemistry

    Cite this

    Quantitative evaluation of catalytic effect of metal chlorides on the decomposition reaction of NaAlH4 . / Hirate, Hiroshi; Saito, Yuki; Nakaya, Ippei; Sawai, Hiroshi; Yukawa, Hiroshi; Morinaga, Masahiko; Nakai, Hiromi.

    In: International Journal of Quantum Chemistry, Vol. 111, No. 5, 04.2011, p. 950-960.

    Research output: Contribution to journalArticle

    Hirate, Hiroshi ; Saito, Yuki ; Nakaya, Ippei ; Sawai, Hiroshi ; Yukawa, Hiroshi ; Morinaga, Masahiko ; Nakai, Hiromi. / Quantitative evaluation of catalytic effect of metal chlorides on the decomposition reaction of NaAlH4 In: International Journal of Quantum Chemistry. 2011 ; Vol. 111, No. 5. pp. 950-960.
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    abstract = "The hydrogen desorption (or decomposition) reaction of NaAlH4 is expressed as NaAlH4 → 1/3 Na3AlH6 + 2/3 Al + H2, and its desorption rate is accelerated by mixing metal chloride catalysts (e.g., TiCl3). This catalytic effect of metal chlorides, MCln, is theoretically estimated in a quantitative way using atomization energy concept. The atomization energies, δEM for metal ion and δECl for chloride ion in various metal chlorides are evaluated using the energy density analysis of the total energy. It is shown that the hydrogen desorption reaction rate increases with increasing n × δEM values of metal chlorides. This indicates that the metal ion in MCln interacts mainly with hydrogen or [AlH 4]- complex anion in NaAlH4. To confirm this calculated result, experiments are performed using NaAlH4 mixed with Ti-based catalysts. The hydrogen desorption rate is enhanced in the order, TiCl3 > TiO2 > Ti metal nanopowder, indicating that the Ti ions in TiCl3 or TiO2 work to promote the catalytic reaction more effectively than the neutral Ti atoms in Ti metal nanopowder.",
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    AU - Yukawa, Hiroshi

    AU - Morinaga, Masahiko

    AU - Nakai, Hiromi

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    AB - The hydrogen desorption (or decomposition) reaction of NaAlH4 is expressed as NaAlH4 → 1/3 Na3AlH6 + 2/3 Al + H2, and its desorption rate is accelerated by mixing metal chloride catalysts (e.g., TiCl3). This catalytic effect of metal chlorides, MCln, is theoretically estimated in a quantitative way using atomization energy concept. The atomization energies, δEM for metal ion and δECl for chloride ion in various metal chlorides are evaluated using the energy density analysis of the total energy. It is shown that the hydrogen desorption reaction rate increases with increasing n × δEM values of metal chlorides. This indicates that the metal ion in MCln interacts mainly with hydrogen or [AlH 4]- complex anion in NaAlH4. To confirm this calculated result, experiments are performed using NaAlH4 mixed with Ti-based catalysts. The hydrogen desorption rate is enhanced in the order, TiCl3 > TiO2 > Ti metal nanopowder, indicating that the Ti ions in TiCl3 or TiO2 work to promote the catalytic reaction more effectively than the neutral Ti atoms in Ti metal nanopowder.

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