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

5 Citations (Scopus)

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

Keywords

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

ASJC Scopus subject areas

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

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