Pt encapsulated hollow mesoporous SiO 2 sphere catalyst for sulfuric acid decomposition reaction in SI cycle Hassnain Abbas Khan a,b,1 , Muhammad Ibrahim Iqbal a,b,1 , Ahsan Jaleel a,b , Imran Abbas a,b , Syed Asad Abbas a,b , Kwang Deog-Jung a,b,* a Clean Energy and Chemical Engineering, University of Science and Technology, 217, Gajeong-ro Yuseong-gu, Daejeon, Republic of Korea b Clean Energy Research Centre, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea article info Article history: Received 1 February 2018 Received in revised form 6 July 2018 Accepted 26 July 2018 Available online xxx Keywords: Sulfuric acid decomposition SiO 2 hollow sphere Hollow sphere-supported Pt catalyst P25-TiO 2 supported Pt catalyst abstract Sulfuric acid (SA) decomposition is one of three key reactions in sulfur Iodine (SI) cycle to produce hydrogen. The catalysts for the decomposition should be active and stable in a wide temperature range of 550e900  C. Pt based catalysts have been explored for the application, but suffered from the Pt loss in high temperature (~850  C). TiO 2 and Al 2 O 3 are used as a support. They can stabilize Pt metal at higher temperature, but are degraded at the temperature lower than 700  C. SiO 2 supports with a high surface area are relatively stable in a sulfuric acid vapor stream, but the lower interaction with Pt results in high Pt sintering and Pt loss. Both Pt loss and Pt sintering at the high temperature are originated from Pt vaporization. Here, Pt metallic components are placed at the inner wall of hollow mesoporous SiO 2 spheres (Pt-HMSS) to preserve Pt components even at 850  C. PtOx vapor vaporized during the SA decomposition can be re-dispersed on the inner wall of meso- porous SiO 2 shell, which can suppress the Pt loss; (1) temperature at outer wall is higher than temperature at inner wall during the endothermic reaction on Pt at the inner wall, (2) the mesoporous shell afford the long path to suppress the diffusion of PtOx vapor at the inner wall to the outer wall. Pt catalyst at the outer walls of hollow mesoporous SiO 2 spheres (HMSS-Pt) is prepared and tested for clarifying the hypothesis. Additionally, TiO 2 - Pt catalyst, one of highly stable catalytic systems for the SA decomposition, is also pre- pared and compared with the Pt-HMSS catalyst. © 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. * Corresponding author. Clean Energy and Chemical Engineering, University of Science and Technology, 217, Gajeong-ro Yuseong-gu, Daejeon, Republic of Korea. E-mail address: jkdcat@kist.re.kr (K. Deog-Jung). 1 These two authors contributed equally. Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2018) 1 e11 https://doi.org/10.1016/j.ijhydene.2018.07.161 0360-3199/© 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Khan HA, et al., Pt encapsulated hollow mesoporous SiO 2 sphere catalyst for sulfuric acid decom- position reaction in SI cycle, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/j.ijhydene.2018.07.161