Exhaust gas catalysts for heavy-duty applications: influence of the Pd particle size and particle size distribution on the combustion of natural gas and biogas

In this study, an experimental investigation concerning exhaust gas catalys ts for heavy-duty diesel engines fuelled by natural gas or biogas is presen ted. Miniature monoliths, 2.5 wt% Pd/Al2O3, have been prepared, characteris ed and tested. Various methods have been used in order to obtain different palladium particle sizes, including incipient wetness and microemulsion tec hnique. Crystallite sizes between 2 and 40 nm were obtained. We observed th at the metal particle size influences the activity for methane oxidation. M oreover, the homogeneity of the active material was found to affect the rea ction rate.