Available online at www.sciencedirect.com ScienceDirect Materials Today: Proceedings 3 (2016) 2735–2743 www.elsevier.com/locate/procedia 2214-7853 © 2016 Published by Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the Conference Committee of 6th International Conference on Advanced Nanomaterials (ANM2015) © 2015 ANM2015. All rights reserved. 6th International conference on Advanced Nanomaterials Hydrogenation/Dehydrogenation Kinetics Study of Reacted Ball Milled (MgH 2 ) 100-x /(Ni) y /(Nb 2 O 5 ) z ) x Nanocomposite Powders M. Sherif El-Eskandarany, H. S. AlMatrouk*, and Ehab Shaban Nanotechnology and Advanced Materials Program, Energy and Building Research Center, Kuwait Institute for Scientific Research, Safat 13109, Kuwait Abstract Nanocrystalline powders of MgH 2 was synthesized under a high hydrogen gas pressure (50 bar), using reactive ball milling technique operated at ambient temperature under 50 bar of a hydrogen gas atmosphere. The MgH 2 powders obtained after 200 h of continuous RBM time composed of β and γ phases. The powders possessed nanocrystalline characteristics with an average grain of about 10 nm in diameter. The time required for complete hydrogen absorption and desorption measured at 250 o C was 500 s and 2500 s, respectively. In order to improve the hydrogenation/dehydrogenation kinetics, three different types of nanocatalysts (metallic Ni, Nb 2 O 5 and (Ni) x /(Nb 2 O 5 ) y ) were utilized with different weight percentages and independently ball milled with the as-synthesized MgH 2 powders for 50 h under 50 bar of a hydrogen gas atmosphere. The results have shown that the as-prepared nanocomposite MgH 2 /5Ni/5Nb 2 O 5 powders possessed superior hydrogenation/dehydrogenation characteristics, indexed by low values of activation energy for β-phase (68 kJ/mol) and γ-phase (74 kJ/mol). Moreover, this nanocomposite system shows excellent hydrogenation/dehydrogenization behavior indexed by the short time required to uptake (41 s) and release (121 s) of 5 wt.% H 2 at 250 o C. © 2016 Published by Elsevier Ltd. Selection and Peer-review under responsibility of the Conference Committee of 6th International Conference on Advanced Nanomaterials (ANM2015) © 2015 ANM2015. All rights reserved. Keywords: Reactive ball milling: metal hydrides; nanocomposites; nanocatalysts; gas-solid reaction; cycle-life-time. * Corresponding author. Tel.: +965-24989253; Fax: +965-24989139. E-mail address: hasan.almatrouk@gmail.com