Simultaneous utilization of two different membranes for intensification of ultrapure hydrogen production from recuperative coupling autothermal multitubular reactor M. Bayat a , M.R. Rahimpour a,b, * a Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz 71345, Iran b Gas Center of Excellence, Shiraz University, Shiraz 71345, Iran article info Article history: Received 23 December 2010 Received in revised form 6 February 2011 Accepted 9 February 2011 Available online 11 April 2011 Keywords: Ultrapure hydrogen production H 2 O removal Methanol synthesis Pd/Ag membrane H-SOD membrane Steady-state heterogeneous model abstract The potential of simultaneous hydrogen production and in situ water removal in a ther- mally coupled multitubular two-membrane reactor (TCTMR) were studied numerically. Methanol synthesis is carried out in exothermic side with H-SOD membrane and supplies the necessary heat for the endothermic side. Dehydrogenation of cyclohexane is carried out in endothermic side with hydrogen-permselective Pd/Ag membrane wall. Therefore, the proposed reactor consists of two membranes, one for separation of pure hydrogen from endothermic side and another one for separation of water from exothermic side. The motivation for in situ H 2 O removal during methanol synthesis by using H-SOD membranes is to displace the wateregas shift equilibrium to enhance conversion of CO 2 to improve methanol productivity. A steady-state heterogeneous model is developed to analyze the operation of the coupled methanol synthesis. The proposed model has been used to compare the performance of a TCTMR with conventional reactor (CR) and thermally coupled membrane reactor (TCMR) at identical process conditions. This comparison shows that TCTMR in addition to possessing advantages of a TCMR has a more favorable profile of temperature and increased productivity compared with other reactors. Furthermore, lower water production rate in TCTMR reduces catalyst re-crystallization. Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction According to the problems induced by the shortage of fossil energy and global warming, hydrogen is expected to be a promising energy vector for the near future [1]. Hydrogen has been nominated as a renewable and alternative energy. It is at best as an energy carrier [2e4]. 1.1. Hydrogen production Hydrogen commercially produces by steam reforming of methane and other fossil fuels. In such cases, however, the same amount of carbon dioxide is released during the produc- tion of hydrogen as that formed by direct combustion of fuels. This method produces toxic and corrosive components such as * Corresponding author. Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz 71345, Iran. 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) 7310 e7325 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.2011.02.051