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Title: A benign synthesis of alane by the composition-controlled mechanochemical reaction of sodium hydride and aluminum chloride

Solid-state mechanochemical synthesis of alane (AlH 3) starting from sodium hydride (NaH) and aluminum chloride (AlCl 3) has been achieved at room temperature. The transformation pathway of this solid-state reaction was controlled by a stepwise addition of AlCl 3 to the initial reaction mixture that contained sodium hydride in excess of stoichiometric amount. As in the case of previously investigated LiH–AlCl 3 system, complete selectivity was achieved whereby formation of unwanted elemental aluminum was fully suppressed, and AlH 3 was obtained in quantitative yield. Reaction progress during each step was investigated by means of solid-state NMR and powder X-ray diffraction, which revealed that the overall reaction proceeds through a series of intermediate alanates that may be partially chlorinated. The NaH–AlCl 3 system presents some subtle differences compared to LiH–AlCl 3 system particularly with respect to optimal concentrations needed during one of the reaction stages. Based on the results, we postulate that high local concentrations of NaH may stabilize chlorine-containing derivatives and prevent decomposition into elemental aluminum with hydrogen evolution. As a result, complete conversion with quantitative yield of alane was confirmed by both SSNMR and hydrogen desorption analysis.
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  1. Ames Lab. and Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0022-2461; PII: 1219
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Materials Science
Additional Journal Information:
Journal Volume: 52; Journal Issue: 20; Journal ID: ISSN 0022-2461
Research Org:
Ames Lab., Ames, IA (United States)
Sponsoring Org:
Country of Publication:
United States
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; alane; ball milling; hydrogen storage; mechanochemistry; metathesis; solid-state NMR
OSTI Identifier: