Effect of ZrC Nanopowders on Enhancing the Hydro/Dehydrogenation Kinetics of MgH2 Powders.

Mohamed Sherif El-Eskandarany,Fahad Al-Ajmi,Naser Ali,Mohammad Banyan

doi:10.3390/molecules26164962

Mohamed Sherif El-Eskandarany, Fahad Al-Ajmi + Show 2 more

Open Access

https://doi.org/10.3390/molecules26164962

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Abstract

Hydrogen has been receiving great attention as an energy carrier for potential green energy applications. Hydrogen storage is one of the most crucial factors controlling the hydrogen economy and its future applications. Amongst the several options of hydrogen storage, light metal hydrides, particularly nanocrystalline magnesium hydride (MgH2), possess attractive properties, making them desired hydrogen storage materials. The present study aimed to improve the hydrogen storage properties of MgH2 upon doping with different concentrations of zirconium carbide (ZrC) nanopowders. Both MgH2 and ZrC were prepared using reactive ball milling and high-energy ball milling techniques, respectively. The as-prepared MgH2 powder was doped with ZrC (2, 5, and 7 wt%) and then high-energy-ball-milled for 25 h. During the ball milling process, ZrC powders acted as micro-milling media to reduce the MgH2 particle size to a minimal value that could not be obtained without ZrC. The as-milled nanocomposite MgH2/ZrC powders consisted of fine particles (~0.25 μm) with a nanosized grain structure of less than 7 nm. Besides, the ZrC agent led to the lowering of the decomposition temperature of MgH2 to 287 °C and the reduction in its apparent activation energy of desorption to 69 kJ/mol. Moreover, the hydrogenation/dehydrogenation kinetics of the nanocomposite MgH2/ZrC system revealed a significant improvement, as indicated by the low temperature and short time required to achieve successful uptake and release processes. This system possessed a high capability to tackle a long continuous cycle lifetime (1400 h) at low temperatures (225 °C) without showing serious degradation in its storage capacity.

Highlights

The global use of fossil fuels has increased drastically as people’s standard of living has improved
XX-ray diffraction (XRD) pattern of as rreecceeived hhccp MMgg ppoowwddeerr iiss ddiissppllaayyeedd iinn ((aa)), wwhheerree the XXRD ppatterns of tthhe ppoowwders oobtained after reactive ball milling (RBM) for 1, 3, 66 aanndd 2255 hh aarree pprreesseenntteeddiinn((bb–),e()c, )r,e(sdp)eactnidve(ley)., respectively
Reactive ball milling was employed to fabricate nanocrystalline MgH2 powders in a gas–solid reaction fashion performed under high hydrogen pressure (~50 bar) for 25 h to 50 h

Summary

Introduction

The global use of fossil fuels has increased drastically as people’s standard of living has improved. Driven by increasing carbon dioxide emissions, will wreak havoc on society [1]. The threat of pollution will be exacerbated by the forced expansion of using low-grade fossil fuels. Improved living standards will raise the demand for chemicals derived from fossil fuels, which will be used to make higher-value end-use commodities such as plastics and pharmaceuticals. Due to the severe rivalry over dwindling supplies, the price of energy and chemicals derived from fossil fuels will increase. Due to environmental and health points of view, fossil fuels emit carbon dioxide and other harmful air pollutants such as SO2 and NOx when burned [2]

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