Hydrogen as an energy carrier: A comparative study between decalin and cyclohexane in thermally coupled membrane reactors in gas-to-liquid technology M.R. Rahimpour*, A. Mirvakili, K. Paymooni Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz 71345, Iran article info Article history: Received 12 January 2011 Received in revised form 26 February 2011 Accepted 4 March 2011 Available online 17 April 2011 Keywords: FischereTropsch synthesis Hydrogen production Decalin GTL technology Hydrogen carrier Thermally coupled membrane reactor abstract Due to proposing hydrogen as the main energy carrier, technologies including production, storage and utilization of hydrogen have attracted increasing attention recently. Regarding this, the feasibility of decalin as a promising hydrogen carrier is investigated in this study. The performance of decalin thermally coupled membrane reactor (DCTCMR) is compared with cyclohexane thermally coupled membrane reactor (CTCMR) for FischereTropsch synthesis (FTS) in gas-to-liquid (GTL) technology. Some important parameters such as hydrogen production rate, H 2 recovery yield, exothermic and endothermic temperature profiles and etc. are considered as criteria to recognize the most appropriate configuration. A comparison between the modeling results of two coupled configurations shows that DCTCMR is superior to CTCMR owing to achieving remarkably higher hydrogen production (seventeen times) compared with CTCMR. Furthermore, considerably higher H 2 recovery yield (about twelve times) and faster dehydrogenation reaction rate in DCTCMR than CTCMR proposes decalin as one of the best hydrogen carriers. This study demonstrates the superiority of DCTCMR to CTCMR owing to achieving remarkably higher hydrogen production rate, H 2 recovery yield and recognizing decalin as an appropriate hydrogen carrier. Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction Since the exothermic and endothermic reactions take place simultaneously in the same fixed-bed reactor, the equipment size can be remarkably reduced and the utilization efficiency of energy and resources can be significantly improved. A variety of coupling schemes have been reported in the literature [1e5]. The FTS exothermic reactions are coupled with an endothermic reaction to reduce the thermal losses. Dehydrogenation is an attractive endothermic reaction for coupling with FTS, because dehydrogenation reaction is highly endothermic and produces hydrogen. 1.1. FischereTropsch synthesis (FTS) In order to realize more comprehensive description of FTS process, the kinetic model and a few mathematical modeling studies on FTS are provided as follows: The kinetics of the gasesolid FTS over a commercial FeeCueKeSiO 2 catalyst was studied in a continuous spinning basket reactor [6]. Schulz et al. extended their existing kinetic model by taking into account olefin hydrogenation, isomeri- zation (double bond shift) and incorporation and in particular chain length dependent product solubilities [7]. Eliason et al. obtained rate data for FTS on unsupported Fe and Fe/K * Corresponding author. Tel.: þ98 711 2303071; fax: þ98 711 6287294. E-mail address: rahimpor@shirazu.ac.ir (M.R. Rahimpour). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 36 (2011) 6970 e6984 0360-3199/$ e see front matter Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2011.03.007