Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel Full Length Article TiO 2 as a catalyst for hydrogen production from hydrogen-iodide in thermo- chemical water-splitting sulfur-iodine cycle Amit Singhania ⁎ , Ashok N. Bhaskarwar Department of Chemical Engineering, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi, India GRAPHICAL ABSTRACT ARTICLE INFO Keywords: Titania Catalytic activity Hydrogen-iodide decomposition Hydrogen Sulfur-iodine cycle ABSTRACT In this work, TiO 2 nanoparticles have been prepared by the sol–gel (at different calcination temperatures) and solution-combustion method for hydrogen-iodide decomposition in thermo-chemical water-splitting sulfur-io- dine (SI) cycle for hydrogen production. The sol-gel method derived TiO 2 (TiO 2 -SGM-300 and TiO 2 -SGM-500) provide smaller nanoparticles as compared to the solution-combustion (TiO 2 -SCM). TEM revealed a particle size of around 4–5 nm of TiO 2 -SGM-300. XRD and Raman confirmed that TiO 2 -SGM-300 and TiO 2 -SGM-500 ex- hibited pure anatase phase, whereas a small amount of rutile phase was observed in TiO 2 -SGM-700 and TiO 2 - SCM samples. It is found that with increase in calcination temperatures during sol-gel method, the average particle size of TiO 2 increases and specific surface area decreases. Commercial TiO 2 (Degussa P-25) was used for the comparison purpose. As far as the author knows, TiO 2 has been used here for the first time for hydrogen- iodide decomposition. The hydrogen-iodide decomposition experiments were carried out in a vertical-fixed bed quartz reactor at a WHSV of 12.9 h -1 under atmospheric pressure. The order of catalytic activity was as follows: TiO 2 -SGM-300 > TiO 2 -SCM > TiO 2 -COMM (commercial). Also, it was observed that the hydrogen-iodide conversion decreases with increase in calcination temperatures of TiO 2 during sol–gel method. Their activity was as follows: TiO 2 -SGM-300 > TiO 2 -SGM-500 > TiO 2 -SGM-700. TiO 2 -SGM-300 catalyst also showed a reason- able time-on-stream stability of 6 h for hydrogen-iodide decomposition. The apparent activation energy of TiO 2 - SGM-300 is found to be 72.29 kJ mol -1 . This shows that the TiO 2 has a potential of generating hydrogen from hydrogen iodide in SI cycle. This can further be explored as a catalyst support using some non-precious and precious metal catalysts for hydrogen-iodide decomposition. https://doi.org/10.1016/j.fuel.2018.02.130 Received 1 November 2017; Received in revised form 16 February 2018; Accepted 20 February 2018 ⁎ Corresponding author. E-mail address: amit.singhania2008@gmail.com (A. Singhania). Fuel 221 (2018) 393–398 0016-2361/ © 2018 Elsevier Ltd. All rights reserved. T