Reversible hydrogen storage in the LieMgeNeH system e The effects of Ru doped single walled carbon nanotubes on NH 3 emission and kinetics Dervis ‚ Emre Demirocak a, *, Sesha S. Srinivasan a,b , Manoj K. Ram a , John N. Kuhn c , Ranjani Muralidharan d , Xiao Li d , D. Yogi Goswami a , Elias K. Stefanakos a a Clean Energy Research Center, College of Engineering, University of South Florida, Tampa, FL 33620, USA b Department of Physics, College of Arts and Sciences, Tuskegee University, Tuskegee, AL 36088, USA c Department of Chemical and Biomedical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA d Department of Chemistry, College of Arts and Sciences, University of South Florida, Tampa, FL 33620, USA article info Article history: Received 21 March 2013 Received in revised form 28 May 2013 Accepted 31 May 2013 Available online xxx Keywords: Hydrogen storage Lithium amide Magnesium hydride SWCNT Ruthenium doping Ammonia decomposition abstract In this study, the LiNH 2 eMgH 2 (2:1.1) complex hydride system (LieMgeNeH is investigated in terms of hydrogen ab/desorption kinetics and the concomitant NH 3 emission levels. By selecting more intense ball milling parameters, the hydrogen ab/desorption kinetics were improved and the NH 3 emission reduced. However, it is shown that NH 3 emission cannot be completely eliminated during ball milling. Single walled carbon nanotubes (SWCNTs) and 20 wt.% Ru doped SWCNTs are utilized as catalysts to study their effects on NH 3 emission and kinetics characteristics of the LieMgeNeH system. The SWCNT doped sample did not show any kinetics improvement, whereas the SWCNT-20Ru doped sample showed similar kinetics performance as that of the base sample. More importantly, the presence of SWCNT increased the NH 3 emission as compared to the base sample. On the other hand, SWCNT-20Ru doping reduced the NH 3 emission compared to the SWCNT doping, but did not eliminate it completely. As revealed from the mass spectrometry sig- nals, the SWCNT-20Ru catalyst starts to decompose NH 3 at a temperature as low as 200  C. Copyright ª 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction Complex hydrides were subject to intensive research efforts as a solid-state reversible hydrogen storage material for mo- bile and stationary applications during the last decade [1,2]. Among the complex hydrides, amideehydride systems are considered as one of the viable candidates after Chen et al. first reported the promising results for the lithium nitride system in which the reaction steps are given as [3] Li 3 N þ 2H 2 4Li 2 NH þ LiH þ H 2 4LiNH 2 þ 2LiH (1) The theoretical capacity of the Li 3 N system is 10.4 wt.%; however, only the second step of the reaction path, given in Eq. (1) (i.e., LieNeH system hereafter), is practical for * Corresponding author. Tel.: þ1 813 4096864; fax: þ1 813 9742050. E-mail addresses: demirocak@mail.usf.edu, emredemirocak@yahoo.com (D.E. Demirocak). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2013) 1 e11 Please cite this article in press as: Demirocak DE, et al., Reversible hydrogen storage in the LieMgeNeH system e The effects of Ru doped single walled carbon nanotubes on NH 3 emission and kinetics, International Journal of Hydrogen Energy (2013), http:// dx.doi.org/10.1016/j.ijhydene.2013.05.176 0360-3199/$ e see front matter Copyright ª 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijhydene.2013.05.176