Correlation between particle size and hydrogen generation properties on ammonia and lithium hydride system

Abstract

Abstracts For the ammonia (NH 3 ) and lithium hydride (LiH) system, which is one of the promising hydrogen storage materials, the correlation between particle size of LiH and reactivity with NH 3 is investigated to understand the kinetic properties of the system. The pristine LiH shows low reaction yield of less than 10% due to the slow kinetics even after the reaction for 24 h. The activation by the ball-milling drastically improved both of reaction rate and yield, and then more than 80% of reaction proceeded for 24 h in the case of the LiH with the smallest particle size. Thus, the particle size strongly affects the kinetic properties. Furthermore, a thickness of possible NH 3 diffusion into the LiH surface for the 24 h reaction is estimated to be 20 nm assuming that the LiH particles are an ideal spherical shape. Therefore, the rate-determining step of the system would be the NH 3 diffusion process.