Mechanochemical synthesis of Ce3Al11 powder and its catalytic effect on the hydrogen sorption properties of NaAlH4

Abstract

Mechanochemical synthesis of the Ce3Al11 powder was performed through a reaction among CeCl3, AlCl3 and NaH powders. alpha-Ce3Al11 particles with an average size of 250 nm were obtained. The catalytic effect of the synthesized Ce3Al11 on the hydrogen sorption properties of NaAlH4 was investigated. The hydrogen absorption kinetics of NaAlH4 with Ce3Al11 was significantly enhanced and the hydrogen capacity was improved compared to those properties of NaAlH4 with CeCl3. This can be attributed to the fine distribution of the Ce3Al11 catalyst in NaAlH4 during ball milling. Although the volume of the NaAlH4 pellets generally tends to increase during the hydrogen sorption cycles, the volume expansion of the pellet of NaAlH4 with Ce3Al11 was relatively low with a small pore fraction compared to that of the pellet of NaAlH4 with conventional chloride catalysts such as CeCl3, TiCl3 and TiCl4. The use of a nonchloride catalyst appears to provide an effective approach for suppressing the volume expansion of NaAlH4 pellets during the hydrogen sorption cycles. (C) 2019 Elsevier B.V. All rights reserved.