Separation and Purification Technology 56 (2007) 25–37 Purification of hydrogen from hydrocarbons by adsorption for vehicles application Yousef Swesi a,∗ , Philippe Kerleau a , Isabelle Pitault a , Fabien Heurtaux b , Didier Ronze c a LGPC, CNRS/ESCPE, 43 bd du 11 Novembre 1918, BP 2077, 69616 Villeurbanne Cedex, France b RENAULT, Direction de la Recherche, 1 Avenue du Golf, 78288 Guyancourt, France c Universit´ e Claude Bernard Lyon 1, IUT A D´ epartement de G´ enie Chimique, 43 bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France Received 19 June 2006; received in revised form 14 September 2006; accepted 16 September 2006 Abstract Adsorption of toluene and methylcyclohexane on various adsorbents was investigated to develop a process for the purification of hydrogen from H 2 /hydrocarbons mixtures. The development of vehicles using hydrogen in a fuel cell requires the storage of this gas on board for instance as an hydrogenated aromatic hydrocarbon (toluene), hydrogen being recovered by catalytic dehydrogenation. This technique however implies a perfect separation of hydrogen and toluene. An experimental study leads to the choice of a suitable adsorbent: Porapak ® -Q, which gives together a good adsorption capacity (up to 0.078 kg Tol kg -1 PQ ) and good regeneration properties (93% desorption in a given time). A representative model, including the Drachsel model of the adsorption isotherm and the thermal effects, is developed and emphasizes the lack of kinetic limitation. © 2007 Elsevier B.V. All rights reserved. Keywords: Adsorption; Porous polymers; Zeolite; Activated carbon; Hydrogen 1. Introduction Organic compounds such as cycloalkanes can be used for automotive applications to store and transport hydrogen in a safe way compared to pure hydrogen, the storage tanks being the same as the ones used presently. In this case, the cycloalkane is just seen as a hydrogen carrier: the organic hydride is dehy- drogenated on-board and the aromatic is recovered at the fuel station to be regenerated in a hydrogenation plant. Moreover, dehydrogenation reactions (see Heurtaux et al. [1]) occur at rel- atively low temperature (∼380 ◦ C) compared to hydrocarbon reforming process. Nevertheless, proton exchange membrane fuel cell (PEMFC) are known to be subject to poisoning by hydrocarbons, making the purification step a key issue of the process. Among the various available separation methods, only two can be conveniently used for H 2 /hydrocarbons purification in vehicles: adsorption and diffusion through membranes. This work deals only with adsorption, membranes process will be ∗ Corresponding author. Tel.: +33 4 72 43 27 70; fax: +33 4 72 43 16 73. E-mail address: swy@lobivia.cpe.fr (Y. Swesi). studied in another work. The methylcyclohexane/toluene pair was choosen because of its high hydrogen potential (6.1 wt%). In the vehicle, dehydrogenation reactor outlet flow (∼380 ◦ C) is firstly cooled to condense the main part of hydrocarbons at ambient temperature; then the H 2 /hydrocarbons mixture is puri- fied over an adsorbent which should be later regenerated with wet air, coming from a compressor. The main relevant properties are on one hand the maximum adsorption capacity, and on the other hand a regeneration time as short as possible; moreover, the process should not be affected by water. Many adsorbents are commercially available and must be tested: mineral (alumina, silica, zeolites, activated carbon) or organic (porous polymers) compounds. Zeolites are widely used in separation processes. For instance, they are effective adsorbents of hydrocarbons [2] and considered as a trapping material for temporary storage of non-combusted hydrocarbons during the transient cold-start period in the cat- alytic treatment of automotive emissions [3,4]. Inel et al. [5] studied the thermodynamic parameters for the adsorption of some hydrocarbons (n-hexane, cyclohexane and benzene) on 4A and 13X zeolites; these parameters are determined both at finite surface coverage (finite concentration region) 1383-5866/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.seppur.2006.09.023