Production of hydrogen in a Pd-membrane reactor via catalytic reforming of olive mill wastewater Silvano Tosti a,⇑ , Carmela Cavezza b , Massimiliano Fabbricino b , Ludovico Pontoni b , Vincenzo Palma c , Concetta Ruocco c a ENEA, Unità Tecnica Fusione, C.R. ENEA Frascati, Via E. Fermi 45, Frascati (RM) I-00044, Italy b Dept. of Civil, Architectural and Environmental Engineering, Univ. of Naples Federico II, Via Claudio 21, Naples I-80125, Italy c Dept. of Chemical Engineering, Univ. of Salerno, Via Giovanni Paolo II 132, Fisciano (SA) I-84084, Italy highlights  Hydrogen has been produced via catalytic reforming of olive mill waste water.  A noble metals based catalyst supported on rare earth mixed oxides was studied.  The new catalyst showed high selectivity and reduced coke and methane formation.  Up to 3.25 kg of hydrogen have been produced per ton of olive mill wastewater. article info Article history: Received 27 February 2015 Received in revised form 30 March 2015 Accepted 1 April 2015 Available online 8 April 2015 Keywords: Olive mill wastewater Reforming Hydrogen production Pd-membrane Pt-catalysts abstract Olive mill wastewater (OMW) contributes to environmental issues in Mediterranean regions because of its poor biodegradability and high phytotoxicity. Among the different processes proposed for the treat- ment of OMW, thermochemical treatments are advantageous as they can recover hydrogen-rich gas mixtures; thus, they can convert a waste into an energetic source. In this work, a noble metals based catalyst supported on rare earth mixed oxides was studied for its ability to reform OMW in a Pd–Ag tubular membrane reactor. The experimental results were compared with those obtained in a previous study using a Pt/Al 2 O 3 catalyst. After filtration and concentration via distillation, OMW was treated in a Pd–Ag tube of thickness 0.143 mm, diameter 10 mm, and length 146 mm. The membrane tube was filled with 4.8 g of catalyst. The reaction tests were performed at 450 °C in the pressure range 100–500 kPa and demonstrated the capability of the membrane reactor to produce up to 3.25 kg of hydrogen per ton of OMW. Higher values of hydrogen recovery and hydrogen yield were measured at 500 kPa when the hydrogen permeated in the shell side was up to 80% of all the hydrogen produced and about 35 wt% of the total organic carbon (TOC) fed. Investigation of carbon formation showed that only 1.2% of the fed carbon was responsible for coke for- mation by demonstrating that the new catalyst, although tested at low temperature, was effective to limit this phenomenon. When compared to the commercial Pt-based catalyst, the new catalyst exhibited higher selectivity toward the reforming reaction, allowing it to significantly reduce the formation of methane and coke; thus, it exhibited higher hydrogen yield and greater durability. Ó 2015 Elsevier B.V. All rights reserved. 1. Introduction The first evidence of olive tree cultivation has been traced to about 5000–6000 years ago in the eastern Mediterranean basin. From there it expanded to all the Mediterranean countries, which are presently responsible for 95% of worldwide olive oil production [1]. Today, olive tree cultivation covers 9.4 million ha and produces 16 Mt of olives processed into 2.6 Mt of oil. The main byproducts of olive oil production are the residual semi-solid matter of the olive pulp after oil removal (pomace), twigs and leaves, and olive mill wastewater (OMW). Although OMW is characterized by a seasonal production (Oct.–Dec.) of moderate extent (approximately 30 Mm 3 per year) compared to other agricultural wastes, its environmental http://dx.doi.org/10.1016/j.cej.2015.04.001 1385-8947/Ó 2015 Elsevier B.V. All rights reserved. ⇑ Corresponding author. Tel.: +39 0694005160; fax: +39 06 94005147. E-mail address: silvano.tosti@enea.it (S. Tosti). Chemical Engineering Journal 275 (2015) 366–373 Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej