Effect of CO on hydrogen storage performance of KF doped 2LiNH2Â +Â MgH2 material

(2LiNH2 + MgH2) material is one of the most promising hydrogen storage materials. In applications, CO impurity in hydrogen has an effect on the hydrogen storage performance of (2LiNH2 + MgH2) material. In this work, the effect of CO on the hydrogen storage properties of KF doped (2LiNH2 + MgH2) material was investigated by using hydrogen containing 1 mol% CO as the hydrogenation gas source. The results indicate that the hydrogen desorption capacity of the hydride decreases from 4.73 wt.% to 3.88 wt.% after 5 hydrogenation cycles. The decrease of the capacity is attributed to the permanent loss of the NH2 caused by the formation of Li2CN2 and KCN. Moreover, the hydrogen desorption kinetics declines obviously, and the dehydrogenation activation energy increases from 122.1 kJ/mol to 132.0 kJ/mol. Furthermore, it is found that the hydrogen desorption kinetics cannot be recovered to the initial level after re-milling. The main reason for these is that the catalytic effect on (Mg(NH2)2 + 2LiH + 0.05KF) system disappears due to the transformation from KH to KCN.