EXHAUST GAS EMISSIONS FROM ETHANOL FUELLED HEAVY DUTY VEHICLES

The purpose of the project was to contribute to the development of more efficient and better suited catalysts for ethanol fuelled diesel vehicles, by characterization of the emissions of both regulated and unregulated exhaust emission components at different driving conditions for a bus engine. Measurements on three commercial and one prototype catalyst, which has been developed for ethanol fuelled diesel vehicles in another KFB supported project, were performed at 22 "steady-state" loading points. The measurements included the regulated emission components carbon monoxide, hydrocarbons and nitrogen oxides and the non-regulated emission components ethanol, formaldehyde, acetaldehyde, acetic acid and some light hydrocarbons. In addition were the pressure drop and temperatures over the catalysts measured. The investigation shows that there are large differences between the commercial catalysts regarding the oxidation capacity and the selectivity. One of the catalysts showed a very high oxidation capacity but relatively low selectivity. The emissions of both nitrogen dioxide and acetic acid became with this catalyst considerably larger than for the other two. On the other hand the emission of acetaldehyde became lower than for the other two. The catalyst which were developed especially for ethanol fuelled diesel vehicles showed somewhat higher selectivity for ethanol oxidation at most loading points. This gave very low emissions of acetic acid and low emissions of acetaldehyde. This catalyst showed on the other hand some oxidation of NO to NO2. Ageing in diesel exhaust did not impair the performance of this catalyst. The choice of ignition improver did not influence the oxidation capacity or the selectivity of the catalysts, considering the variability in the measurements. (A)