Hydrogen absorption and desorption kinetics of MgH2 catalyzed by MoS2 and MoO2

The catalytic effect of MoS2 and MoO2 on the hydrogen absorption/desorption kinetics of MgH2 has been investigated. It is shown that MoS2 has a superior catalytic effect over MoO2 on improving the hydrogen kinetic properties of MgH2. DTA results indicated that the desorption temperature decreased from 662.10 K of the pure MgH2 to 650.07 K of the MgH2 with MoO2 and 640.34 K of that with MoS2. Based on the Kissinger plot, the activation energy of the hydrogen desorption process is estimated to be 101.34 +/- 4.32 kJ mol(-1) of the MgH2 with MoO2 and 87.19 +/- 4.48 kJ mol(-1) of that with MoS2, indicating that the dehydriding process energy barrier of MgH2 can be reduced. The enhancement of the hydriding/dehydriding kinetics of MgH2 is attributed to the presence of MgS and Mo or MgO and Mo which catalyze the hydrogen absorption/desorption behavior of MgH2. The detailed comparisons between MoS2 and MoO2 suggest that S anion has superior properties than O anion on catalyzing the hydriding/dehydriding kinetics of MgH2. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.