from first principles PP-I-1

PP-IV-18H 2 S Purification from Biogas to Feed MCFC by Partial Oxidationon the V 2 O 5 -CeO 2 CatalystPalma V., Barba D., Ciambelli P.University of Salerno, Fisciano, Italyvpalma@unisa.itBiogas can be used for energy production in non conventional systems as the moltencarbonate fuel cells (MCFC). The utilization of the biogas as fuel for MCFC presentsdifferent problems concerning the poisoning of the anode, of the electrolyte, and thedeactivation of oxidation sites by sulphur based compounds (H 2 S, COS) that are alwayspresents in biogas. Because the MCFC have a poor tolerance to these compounds, it’snecessary to reduce the H 2 S concentration at values about 1-5 ppm [1].Direct selective oxidation of H 2 S to sulphur at low temperature appears to be the greatestpromise for the removal from biogas to feed to MCFC.In the previous works vanadium-based catalysts supported on the metal oxides (CeO 2 ,CuFe 2 O 4 , TiO 2 ) were investigated in the range of temperature of 50-250°C.A high activity at T=250°C in terms of H 2 S, O 2 conversions and a low SO 2 selectivity (14%)were obtained on the V 2 O 5 /CeO 2 catalyst. Further investigations were performed to order tominimize the SO 2 selectivity by varying the H 2 S feed concentration (250-1000 ppm), the gashourly space velocity (15,000-45,000 h -1 ) and the feed molar ratio (O 2 /H 2 S=0.4-0.5). A goodresult in terms of selectivity to SO 2 was observed with a sub-stoichiometric feed ratio(O 2 /H 2 S = 0.4) for which the SO 2 selectivity obtained was of 4%.After found the optimal sample, additional tests will be performed to individuate the mainkinetic parameters, and try to obtain preliminary indications concerning the main steps ofreaction mechanism, and the basic kinetics parameters in order to determine the reaction rateexpression. Preliminary investigations on the kinetic parameters showed the reactionmechanism is based on the Langmuir Hinshelwood model with an apparent reaction order forO 2 of 1 and of 1 for H 2 S.References:R. Ciccoli, V. Cigolotti, “Molten Carbonate Fuel Cells fed with biogas: combating H 2 S”, WasteManagement 30 (2010) pp.1018-1024303