Search Results

Reduction of nitrogen oxides in Diesel exhaust gas is a challenging task. This paper reports results from an extensive study using Pt-based catalysts involving synthetic gas activity testing (SCAT), engine bench testing and tests on passenger cars. Preliminary SCAT work highlighted the importance of Pt-dispersion, and both SCAT and bench engine testing yielded comparable NOx conversions under steady state conditions at high HC:NOx ratios. On passenger cars in the European cycle without secondary fuel injection NOx conversion was lower than obtained in the steady state tests. Better conversion was obtained in the FTP cycle, where secondary injection was employed. Higher HC:NOx, ratios and more favourable temperature conditions which were present in the exhaust contributed to this higher conversion.

The addition of oxygen-containing components into gasoline exerts a sustained influence on the cold start and warm-up performance of vehicles. The influences are shown on the basis of test results with motor vehicles. The cold start performance of vehicles with an alternative fuel such as methanol is very strongly dependent on the composition of a properly tailored fuel. This fuel should contain light boiling components for the best performance. Results from methanol fuelled vehicles under cold climate conditions are shown here. The warm-up conditions of an 1.3 l-engine starting at -10°C were researched. The additional fuel required under these conditions for heating all the components of the egine including the coolant and lubricant was calculated after the basic measurement of their temperature rise. The additional fuel required due to the higher friction was investigated by motoring the engine.

Diesel exhaust gas contains low molecular aliphatic carbonyl compounds and strongly smelling organic acids, which are known to have an irritant influence on eyes, nose and mucous membranes. Thus, diesel exhaust aftertreatment has to be considered more critically than that of gasoline engines, with respect to the formation of undesired by-products. The results presented here have been carried out as research work sponsored by the German Research Association for Internal Combustion Engines (FVV). The main objective of the three year project was to evaluate the behaviour of current and future catalyst technology on the one hand (oxidation catalyst, CRT system, SCR process), and regulated and certain selected non-regulated exhaust gas emission components and exhaust gas odour on the other hand.