Room temperature conversion of Mg to MgH2 assisted by low fractions of additives

In recent works, it was noticed that Mg/MgH2 mixed with additives by high energy ball milling allows temperature reductions of H-2 absorption/desorption without necessarily changing thermodynamic properties. Thus, the objective of this work was to investigate which additives, mixed in low fractions with MgH2 powder would act as efficient hydrogen absorption/desorption catalysts at low temperatures, mainly at room temperature (RT). MgH2 mixtures with 2 mol% additives (Fe, Nb2O5 , TiAl and TiFe) were prepared by high energy reactive ball milling (RM). MgH2-TiFe mixture showed the best results, both during desorption at 330 degrees C and absorption at RT. The hydrogen absorption was approximate to 2.67 wt% H-2 in 1 h and approximate to 4.44 wt% H-2 in 16 h (40% and 67% of maximum theoretical capacity, respectively). The MgH2 -TiFe superior performance was attributed to the hydrogen attraction by the created high energy interfaces and strong TiFe catalytic action facilitating the H-2 flow during Mg/MgH2 reactions. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

In recent studies, it was found that high energy ball milling of Mg/MgH2 mixed with additives can reduce the temperature for H-2 absorption/desorption without altering thermodynamic properties. This research aimed to identify efficient hydrogen absorption/desorption catalysts at low temperatures, particularly at room temperature (RT). Among the additives tested in this study, MgH2-TiFe mixture showed the best performance, attributed to the strong catalytic action of TiFe and the high energy interfaces attracting hydrogen gas.