Tuning catalytic performances of cobalt catalysts for clean hydrogen generation via variation of the type of carbon support and catalyst post-treatment temperature Hui Zhang a,* , Yahia A. Alhamed b,c , Abdulrahim Al-Zahrani b,c , Mohammad Daous b,c , Hitoshi Inokawa d , Yoshitsugu Kojima d , Lachezar A. Petrov b,** a School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, Sichuan, China b SABIC Chair of Catalysis, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia c Chemical and Materials Engineering Department, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia d Institute for Advanced Materials Research, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Japan article info Article history: Received 4 June 2014 Received in revised form 16 July 2014 Accepted 30 July 2014 Available online 22 September 2014 Keywords: Clean hydrogen production Ammonia decomposition Carbon materials supported cobalt catalysts abstract Multi-walled carbon nanotubes, three types of activated carbons, single wall carbon nanotube and reduced graphene oxides were used to synthesize nano-sized Co catalysts for H 2 preparation via NH 3 decomposition. Catalyst samples were characterized by number of techniques such as N 2 physisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopes (XPS), Transmission electron microscopy (TEM), CO chemisorption, temperature-programmed reduction (H 2 -TPR) and temperature-programmed desorption (N 2 -TPD). The catalytic activities of the studied catalysts for H 2 production via NH 3 decomposition were measured in a fixed-bed micro-reactor. Co catalyst supported on multi-wall carbon nanotubes has shown the highest catalytic activity. The Co particles size was significantly affected by the variation of the post-treatment temperature. The Co particles size in the range of 4.7e64.8 nm can be effectively controlled by varying post- treatment temperature between 230 and 700  C. The maximum TOF of NH 3 decomposi- tion was registered on cobalt catalyst post-treated at 600  C. Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Introduction Hydrogen is one of the most promising energy carriers. It can be used effectively for production of electricity by means of fuel cells [1,2]. However, the hydrogen storage materials and transportation technologies are imposing limitations, which prevents the large-scale commercialization of fuel cells in automotive industry. On-board hydrogen generation by liquid fuels with high hydrogen density has attracted more and more * Corresponding author. ** Corresponding author. E-mail addresses: huizhang@swpu.edu.cn, zhanghui8047@yahoo.com.cn (H. Zhang), lachezarptrv@yahoo.com, petrov@ic.bas.bg (L.A. Petrov). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 39 (2014) 17573 e17582 http://dx.doi.org/10.1016/j.ijhydene.2014.07.183 0360-3199/Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.