Chemical reactivity and thermal stability of nanometric alkali metal hydrides

The chemical reactivities of nano-NaH particles were compared with those of the commercial ones in three test reactions. Large specific surface areas of these nanoparticles are the main factor for their extremely high reactivity in comparison with their commercial counterpart when these particles are used as a chemical reagent. However, when nano-NaH is used as a cocatalyst with Cp₂TiCl₂, activated surface with high surface energy seems to be the main factor for its high catalytic activity. The thermal stability and chemical reactivity of nanoparticles of lithium hydride, sodium hydride and potassium hydride have been studied. The average particle sizes of lithium, sodium and potassium hydrides before heat treatment are 22, 23 and 19 nm, respectively. Catalytic hydrogenation of olefins and hydrodechlorination of chlorobenzene were employed as test reactions for the chemical reactivities of these nanoparticles treated at different temperatures. The nanoparticles grow with the increase of heat treatment temperature, and the BET specific surface areas decrease simultaneously. An activation of the nanometric hydride surface is evident via the heat treatment under suitable temperatures.