Synthesis of Mg (NH2)2 and Hydrogen Storage Properties of Mg (NH2)2–LiH System

Abstract:

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Mg(NH2)2 was synthesized by first high energy milling MgH2 powder in a 99.995% NH3 atmosphere and then heat treating at 300oC, and hydrogen storage properties of prepared Mg(NH2)2+2.2LiH (molar ratio) had been studied in the temperature range of 150-240oC. It was found that mechanical milling of Mg (NH2)2 and LiH with molar ratio 1:2.2 followed by heat treatment under static hydrogen pressure and dehydrogenating at 208.5oC yields the desired reversible hydrogen storage phase: Li2Mg(NH)2. Desorption kinetics reveal a rapid reaction for the system and the maximum hydrogen capacity can reach 4.6 wt. % at 208.5oC. The system starts to dehydrogenate at 150oC and the Arrhenius activation energy Ea of desorption reaction can be determined to be 25.8 kJ/mol H2 based on the data of kinetics. Additionally, the desorption reaction enthalpy (H) and entropy (S) are calculated to be 42.8 kJ/mol H2 and 149.2 J. K-1/ mol H2 respectively from PCI measurements.

Info:

Periodical:

Advanced Materials Research (Volumes 347-353)

Edited by:

Weiguo Pan, Jianxing Ren and Yongguang Li

Pages:

3609-3615

DOI:

10.4028/www.scientific.net/AMR.347-353.3609

Citation:

K. Zhang et al., "Synthesis of Mg (NH2)2 and Hydrogen Storage Properties of Mg (NH2)2–LiH System", Advanced Materials Research, Vols. 347-353, pp. 3609-3615, 2012

Online since:

October 2011

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$35.00

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