Journal of Membrane Science 351 (2010) 123–130 Contents lists available at ScienceDirect Journal of Membrane Science journal homepage: www.elsevier.com/locate/memsci Hydrogen purification for PEM fuel cells using membranes prepared by ion-exchange of Na-LTA/carbon membranes Francisco J. Varela-Gandía, Angel Berenguer-Murcia, Dolores Lozano-Castelló, Diego Cazorla-Amorós ∗ Departamento de Química Inorgánica, Universidad de Alicante, Ctra. San Vicente del Raspeig s/n, Ap. 99, E-03080 Alicante, Spain article info Article history: Received 14 September 2009 Received in revised form 13 January 2010 Accepted 17 January 2010 Available online 25 January 2010 Keywords: Hydrogen purification LTA zeolite Ion-exchange Supported membrane Permeation properties abstract Modified LTA membranes supported on macroporous carbon discs have been synthesized for the sep- aration of H 2 and CO. These membranes have been prepared by hydrothermal synthesis following the secondary growth method and subsequently ion-exchanged with different alkaline cations in order to modify the zeolite pore size. Their permeation properties have been studied for the purification of a hydro- gen stream (50 vol.%) containing carbon monoxide (1.25 vol.%). For this purpose, a Wicke–Kallenbach cell has been used to perform the separation experiments. Single gas permeation properties and bicomponent mixtures were carried out at three different temperatures (298 K, 398 K and 423 K). Our results indicate that even the K-LTA form would be suitable for the purification of H 2 at room temperature. The Rb- and Cs-forms exhibit the best performance, in which CO permeation is blocked at all temperatures studied. As a result, a high purity H 2 stream may be obtained by employing the Rb- and Cs-membranes derived from Na-LTA/carbon membranes. © 2010 Elsevier B.V. All rights reserved. 1. Introduction In the near future, hydrogen economy is expected to be imple- mented due to the necessity of a clean, efficient energy source and the growing energy crisis [1]. Hydrogen has several advantages as a fuel compared to conventional fossil fuels. Its combustion does not produce pollutants such as carbon dioxide, nitrogen oxides, particles or carbon monoxide and thus presents itself as an inter- esting alternative. It can be used for mobile and stationary devices mainly in transport vehicles. Nevertheless, one of the most sig- nificant shortcomings is the storage of the produced hydrogen, so a more convenient source is needed as a transient solution in order to use it in polymer electrolyte membrane (PEM) fuel cells. The main advantage of PEMs is their being twice as fuel efficient as an internal combustion engine. They operate trans- forming chemical energy into electrochemical energy, avoiding the mechanical requirements and thermodynamic limitations of conventional engines [2]. Hydrogen and oxygen react electrochem- ically and water is produced as remainder so it is a clean process. Ideally, hydrogen may be obtained from renewable sources like water by electrolysis but this technology is not sufficiently devel- oped. Nowadays, hydrocarbon reforming is the most prominent industrial process to produce hydrogen. Vehicles may carry an on- board reformer which would produce a hydrogen stream from the reforming of hydrocarbons like ethanol or methanol. However, in ∗ Corresponding author. Tel.: +34 965903946; fax: +34 965903454. E-mail address: cazorla@ua.es (D. Cazorla-Amorós). the hydrogen produced there are some compounds that poison the platinum electrocatalyst in the anode, more specifically sul- phur and carbon monoxide. Thus, concentrations lower than 10 ppb and 10 ppm, respectively are needed to avoid poisoning. After the reforming step and water gas-shift reaction, the sulphur concen- tration is reduced to desirable levels but another step is needed to reduce the CO concentration from 0.1 to 1% (the concentration of the gaseous stream leaving the reformer) to values around 10 ppm [2]. One alternative to purify hydrogen is the use of hydrogen selective membranes due to their easy preparation, low energy con- sumption and cost effectiveness at low gas volumes [3]. There are several kinds of membranes which can be organized into three cat- egories: (i) polymeric, (ii) metallic and (iii) inorganic membranes like zeolite membranes. Polymer membranes have several advan- tages like having a low cost and not causing significant pressure drops. However, mechanical strength problems and high sensitivity to swelling and compacting reduce their usefulness for this pur- pose [4]. The second type, metallic membranes, have an excellent hydrogen permeance but suffer from hydrogen embrittlement at low temperatures [5]. This is eliminated by using alloys but the product is more expensive. The latter, zeolite membranes, combine the general advantages of inorganic membranes like temperature stability and solvent resistance with those of polymeric membranes as they are composed of a thin homogeneous layer. In the literature, there are many reports on zeolite membranes but the studies have been focused from a different point of view. Caro and Noack [6] have presented a review about zeolite mem- branes which are focused on separating gases like CO 2 or CH 4 from 0376-7388/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.memsci.2010.01.039