An investigation on the reaction pathway between LiAlH4 and LiNH2 via gaseous ammonia

Abstract Interactions between LiAlH 4 and LiNH 2 through a gaseous ammonia intermediate have been investigated. LiAlH 4 and LiNH 2 powders with a molar ratio of 1:1 were separated in two containers inside a reactor and heated from room temperature to 350 °C at a heating rate of 1 °C/min. The results showed that LiNH 2 would decompose into Li 2 NH and NH 3 to certain extent even at a relatively low temperature. Ammonia then reacted with Al and LiH that decomposed from LiAlH 4 , whereupon the chemical equilibrium of the system was altered and the initial reaction temperature was lowered. Ammonia decomposed from LiNH 2 acted as an intermediate. A pathway for the thermal decomposition of the system was proposed as: LiN H 2 + LiAl H 4 → 8 − 3 m 10 L i 2 NH + 2 + 3 m 5 LiH + 2 + 3 m 10 AlN + 8 − 3 m 10 Al + 48 − 3 m 20 H 2 ( 0 m 1 ) The heating rate and initial molar ratio of reactants will affect the value of m , thus the final resultants vary. The theoretical hydrogen desorption capacity of the system was calculated to be in the range of 7.39–7.88 wt.% and a total desorption capacity of 7.37 wt.% was obtained by thermal decomposition.