Hydrogen storage in liquid hydrocarbons: Effect of platinum addition to partially reduced Mo-SiO 2 catalysts N. Boufaden a, * , B. Pawelec b, ** , J.L.G. Fierro b , R. Guil L  opez b , R. Akkari a , M. Said Zina a a Laboratoire de Chimie des Mat eriaux et Catalyse, D epartement de Chimie, Facult e des Sciences de Tunis, Universit e de Tunis El Manar, Campus Universitaire Farhat Hached, Rommana, 1068, Tunis, Tunisia b Instituto de Cat alisis y Petroleoquímica, CSIC, Cantoblanco, 28049, Madrid, Spain highlights  Silica-supported molybdenum and platinum-molybdenum catalyst preparation.  Methylcyclohexane and cyclohexane dehydrogenation on partially reduced catalysts.  Pt/Mo-SiO 2 showed the best activity in methylcyclohexane dehydrogenation.  Mo-SiO 2 acidic character caused its lowest activity.  Better activity of Pt/Mo-SiO 2 in cyclohexane dehydrogenation: Pt and Mo synergy. article info Article history: Keywords: MethylCyclohexane Cyclohexane Dehydrogenation Silica-supported Mo catalysts Silica-supported Pt/Mo catalysts abstract Mesoporous Mo-SiO 2 and SiO 2 synthesized by sol-gel method were impregnated with Pt precursor in order to obtain Pt/Mo-SiO 2 and Pt/SiO 2 catalysts. The catalysts were tested in cyclohexane (CH) and methylcyclohexane (MCH) dehydrogenation reaction and characterized using different techniques. For MCH dehydrogenation, the catalysts' specific initial activity followed the trend: Pt/Mo-SiO 2 > Mo- SiO 2 > Pt/SiO 2 . The synergy effect between Pt and Mo did not occur due to the large contribution of acidity of partially reduced Mo-SiO 2 sample to its catalytic response and to the absence of H 2 spillover for Pt/Mo-SiO 2 . Unlike MCH dehydrogenation, the synergy between Pt and Mo was observed for CH dehy- drogenation over Pt/Mo-SiO 2 catalyst. For both Pt/SiO 2 and Pt/Mo-SiO 2 , the catalyst bifunctionality (metal and acid functions) and the H 2 spillover effect were more important for catalyst behavior in CH dehydrogenation than in MCH dehydrogenation. © 2018 Elsevier B.V. All rights reserved. 1. Introduction The use of hydrogen in vehicles is categorized into two main categories: one, in which hydrogen is burned and other, in which energy is generated by conversion to electricity [1]. Both methods needs gaseous hydrogen, which is known to be difficult for handling and storage due to its extremely low critical temperature (240  C) [2]. Concerning the long-distance transport, the H 2 storage in liquid organic hydrides was reported to be 20% and 30% more cost effective than method of compressed hydrogen and liquefied hydrogen, respectively [3e5]. Recently, techno-economic evaluation of an electricity storage system based on liquid organic hydrogen carriers was presented by Eypasch et al. [6]. Based on assumptions for the year 2030, it was concluded that a completely self-sufficient energy supply system built in 2030 can be compet- itive to the electricity purchase from the grid. There have been numerous number of papers published in the literature on the hydrogen storage and generation. However, finding suitable catalysts for the H 2 storage in liquid organic hy- drocarbons, such as cyclohexane, methylcyclohexane or decalin is still considered as a challenging task. The concept of storing hydrogen in organic liquids is based on the reversible catalytic re- actions of hydrogenation and dehydrogenation of cycloalkanes/ar- omatic hydrocarbons: the hydrogenation of aromatics allows storing hydrogen while the dehydrogenation of cycloalkanes to aromatics is used to extract it [7e11]. Recently, high hydrogen * Corresponding author. ** Corresponding author. E-mail addresses: nesrinebfd@gmail.com (N. Boufaden), bgarcia@icp.csic.es (B. Pawelec). Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys https://doi.org/10.1016/j.matchemphys.2018.01.061 0254-0584/© 2018 Elsevier B.V. All rights reserved. Materials Chemistry and Physics 209 (2018) 188e199