Synthesis of NaAlH_4/Al composites and their applications in hydrogen storage

摘要

In solid-state hydrogen storage in light metal hydrides, nanoconfinement and the use of catalysts represent promising solutions to overcoming limitations such as poor reversibility and slow kinetics. In this work, the morphology and hydrogen desorption kinetics of NaAlH4 melt-infiltrated into a previously developed Ti-based doped porous Al scaffold is analysed. Small-angle X-ray scattering and scanning electron microscopy analysis of low NaAlH4 loading in the porous Al scaffold has revealed that mesopores and small macro pores are filled first, leaving the larger macropores/voids empty. Temperature programmed desorption experiments have shown that NaAlH4-infiltrated porous Al scaffolds show a higher relative H-2 release, with respect to NaAlH4 + TiCl3, in the temperature range 148-220 degrees C, with the temperature of H-2 desorption trending to bulk NaAlH4 with increasing scaffold loading. The Ti-based catalytic effect is reproduced when the dopant is present in the scaffold. Further work is required to increase the mesoporous volume in order to enhance the nanoconfinement effect. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.