The reaction pathway and rate-limiting step of dehydrogenation of the LiHN2+LiHmixture

The reaction pathway and rate-limiting step of dehydrogenation of the LiNH2 + LiH mixture have been investigated. The study reveals that dehydrogenation of the LiNH2 + LiH mixture is diffusion-controlled and the rate-limiting step is NH3 diffusion through the Li2NH product layer outside the LiNH2 shrinking core. This phenomenon is explained based on a model describing the major steps of the dehydriding reaction of the mixture, and related to the evidence obtained from X-ray diffraction and specific surface area measurements of the mixture before and after isothermal hydrogen uptake/release cycles at high homologous temperatures. (C) 2007 Elsevier B.V. All rights reserved.