Catalysis Today 246 (2015) 154–164 Contents lists available at ScienceDirect Catalysis Today j o ur na l ho me page: www.elsevier.com/locate/cattod Improvement in the coating homogeneity in electrosynthesized Rh structured catalysts for the partial oxidation of methane Patricia Benito a,∗ , Marco Monti a , Wout De Nolf b , Gert Nuyts b , Gertjan Janssen a,c , Giuseppe Fornasari a , Erika Scavetta a , Francesco Basile a , Koen Janssens b , Francesca Ospitali a , Domenica Tonelli a , Angelo Vaccari a a Dipartimento di Chimica Industriale “Toso Montanari”. ALMA MATER STUDIORUM-Università di Bologna, Viale Risorgimento 4, 40136, Bologna, Italy b Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium c Health and Technology Department, Leuven University College, Herestraat 49, 3000 Leuven, Belgium a r t i c l e i n f o Article history: Received 6 May 2014 Received in revised form 29 September 2014 Accepted 7 October 2014 Available online 31 October 2014 Keywords: Electrosynthesis Hydrotalcite Rh FeCrAlloy foam Platinum Catalytic partial oxidation of methane a b s t r a c t The precipitation of Rh/Mg/Al and Rh/Al hydroxides on the surface of FeCrAlloy foams by a base elec- trogeneration method was investigated to improve the properties of the deposited film (homogeneity and composition) and therefore the performances of the structured catalysts, obtained by calcination, in the Catalytic Partial Oxidation of CH 4 to syngas. The work focussed on decreasing current gradients within open-cell foam cylinders by increasing the number of electrical contacts from 1 to 3 points to pro- mote a more homogeneous precipitation of the hydroxides. Electrochemical and catalytic tests as well as SEM/EDS and -XRF/XRD analyses allowed to correlate the effect of the number of electrical contact points with materials properties. Lastly, syntheses were performed on Pt plates to study the effect of the electrical behaviour and shape of the support on the composition of the film. A more homogeneous coating of the foam surface was achieved by adopting a configuration with 3 contact points since the reduction of nitrates and water molecules that generates the basic media in the vicinity of the support was enhanced. Layer thicknesses up to 5–15 m were deposited; however, the sequential precipitation of a film with composition closer to the expected one and a layer enriched in Al and Rh (outer layer) was not avoided. The improvement in the coating gave rise to enhanced perform- ances for a sample prepared at -1.1 V for 3000 s. Contrarily, the low adherence of the outer layer in a sample prepared at -1.2 V for 2000 s during both calcination and catalytic tests may be responsible of the unexpected decrease in catalytic performances. The same sequential precipitation was observed by performing the syntheses on Pt plates, showing that the electrical nature the support did not play a key role on this phenomenon. © 2014 Elsevier B.V. All rights reserved. 1. Introduction 3D structures such as honeycombs, open-cell foams, fibers, gauzes and corrugated foils are used as support in structured cata- lysts for the Catalytic Partial Oxidation (CPO) of CH 4 [1–18]. The CPO process converts CH 4 into a syngas with H 2 to CO ratio close to 2 at millisecond contact time and it can be operated under autothermal reaction conditions [19,20]. The gas hourly space velocities (GHSV) values and the high temperatures that may be developed in the cat- alytic bed, make the use of structured catalysts the best option. The structured support showing large geometric area, high void space, ∗ Corresponding author. Tel.: +39 0512093677; fax: +39 0512093679. E-mail address: patricia.benito3@unibo.it (P. Benito). mechanical resistance and in some cases made by a metallic mate- rial, may help to reduce pressure drop and hot spots. Indeed, the heat generated in the upper part of a monolith catalytic bed may diffuse with a thermally conductive support and consumed by fur- ther steam reforming (SR) reactions [10]. The use of foams instead of honeycomb monoliths reduces the start-up and the maximum flow rate that achieves and maintains the steady-state under adia- batic conditions [3]. Moreover, by tailoring the shape and size of the pores, the catalyst activity [5,12], the radiative heat losses [15,21] and the shape of the foam reactor (i.e. converging conical-shaped reactors) [18], the heat management and the presence of hot spots may be controlled as well as the SR promoted. Similar synthetic procedures are reported in the literature to coat supports regardless of their shape and chemical nature [22]; however the procedure may be optimized depending on the type http://dx.doi.org/10.1016/j.cattod.2014.10.003 0920-5861/© 2014 Elsevier B.V. All rights reserved.