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The aim of this paper is to analyse the main concerns related to on board hydrogen catalytic production of fuel cell electric vehicles, starting from different gaseous and liquid fuels. In particular, limits and potentialities of hydrocarbons and alcohols have been examined, considering steam reforming and partial oxidation reactions with reference to emission and efficiency implications. Preliminary results of an experimental investigation on steam reforming of natural gas and liquid hydrocarbons are reported. Furthermore, a mono-dimensional mathematical model of methane steam reformer based on first order kinetics has been developed to simulate the experimental results.

Natural gas is a viable alternative fuel to obtain low exhaust emissions. A heavy duty DI Diesel engine was converted to Otto cycle natural gas operation. Two alternative solutions were compared: lean-burn technology; stoichiometric feed with three-way catalyst and EGR. Power and efficiency were similar for the two above solutions, and exhaust temperature resulted similar to the diesel engine in both cases due to the diluted operation. The lean bum engine met EURO II ECE-R49 limits except for total hydrocarbons. Stoichiometric engine emissions resulted much lower than the limits. Particulate emissions were quite negligible for the two solutions.

Three developmental catalytic converters, provided by different companies, were tested at the exhaust of a SI (spark ignition) NG (natural gas) engine for bus application. The catalysts were all based on noble metals: Pt (platinum), Pd (palladium), Rh (rhodium) and differed in size, metal loading and active phase composition. Emission evaluation was performed according to the European ECE-R49 procedure (13 mode cycle), in stoichiometric and lean-burn conditions. In addition to regulated emission measurement, speciation of NMHC (non-methane hydrocarbons) and carbonyl compounds was performed. The results showed that all the catalyst compositions considered allowed the European emission limits to be complied when the engine operated in stoichiometric conditions, while the overall best performance in the lean region was obtained on the catalyst with noble metal composition Pd:Rh=21:1.

This paper presents the experimental results obtained on Fuel Cell System designed and realized in Istituto Motori and based on 16 kW PEM (Proton Exchange Membrane) stack. This activity is part of the HBUS Project, whose goal is the realization of a midi-bus for public transportation in urban areas based on fuel cell technology. This Project involves several private and public partners, comprising Istituto Motori as research institution, I2T3 (Industrial Innovation Through Technological Transfer) agency for technological innovation and project management, together with public transportation companies and vehicle component makers.