Enhancement of Hydrogen Desorption from Nanocomposite
Prepared by Ball Milling MgH<sub>2</sub> with In Situ Aerosol Spraying
LiBH<sub>4</sub>
Zhao Ding
Leon Shaw
10.1021/acssuschemeng.9b03724.s001
https://acs.figshare.com/articles/journal_contribution/Enhancement_of_Hydrogen_Desorption_from_Nanocomposite_Prepared_by_Ball_Milling_MgH_sub_2_sub_with_In_Situ_Aerosol_Spraying_LiBH_sub_4_sub_/9684692
The
prospect of LiBH<sub>4</sub> + MgH<sub>2</sub> mixtures has
been limited by their sluggish kinetics despite their excellent hydrogen
storage capacity theoretically. This study demonstrates that ball
milling with aerosol spraying (BMAS) established in the previous study
can not only tune the thermodynamics but also improve the kinetics
for hydrogen release from a LiBH<sub>4</sub> + MgH<sub>2</sub> mixture.
The improved thermodynamics has been evaluated from the viewpoint
of the significantly heightened dissociation pressure. Nine different
kinetics models have been used to analyze the solid-state dehydrogenation
behavior of the BMAS powder with 50% LiBH<sub>4</sub> at 265 °C.
The kinetics analysis reveals that the rate-limiting step of this
BMAS powder is initially controlled by the nucleation/growth process
but then is changed to moving-phase boundary control and finally to
diffusion control as the number of dehydrogenation/rehydrogenation
cycles increases. The change in the dehydrogenation kinetics with
increasing cycles has been attributed to the presence of three parallel
dehydrogenation reaction pathways and their different contributions
to the overall H<sub>2</sub> release as the number of cycles increases.
Thermal analysis indicates that the apparent activation energy of
the BMAS powder has been reduced by 23.3 and 30.6 kJ/mol when compared
to that of bulk LiBH<sub>4</sub> and ball-milled MgH<sub>2</sub> +
C mixtures, respectively, revealing that BMAS is an effective method
to promote hydrogen release from LiBH<sub>4</sub> + MgH<sub>2</sub> mixtures.
2019-08-19 19:38:10
kinetic
dehydrogenation reaction pathways
moving-phase boundary control
hydrogen release
MgH 2 mixture
MgH 2 mixtures
hydrogen storage capacity
H 2 release
BMAS powder
LiBH 4
Ball Milling MgH 2
ball-milled MgH 2
bulk LiBH 4