Kinetics of the reaction of water vapour with crystalline lithium hydride
Abstract
The kinetics of the reaction of water vapour with crystalline lithium hydride to produce hydrogen, and either lithium oxide or hydroxide, has been investigated over the temperature range 0–121°C. The chemical nature of the solid product is determined solely by the amount of water vapour added in any single dose; when this is only sufficient to react with a single surface layer of lithium hydride or less, the oxide is found almost exclusively but when there is sufficient water to react with several layers, only the hydroxide is formed. On introduction, water vapour is rapidly and almost completely removed from the gas phase by the solid hydride (and products) but the hydrogen-producing process continues for several hours by reaction of sorbed water with the hydride. Diffusion of sorbed water to the reaction interface is not rate-controlling.
The kinetics of hydrogen production, irrespective of the chemical nature of the product, is adequately represented by