Regulated and speciated hydrocarbon emissions from a catalyst equipped internal combustion engine

In the present work, the effect of engine operating conditions on its exhaust emissions and on catalytic converter operation is studied. A 4-cylinder OPEL 1.6 l internal combustion engine equipped with a hydraulic brake dynamometer was used in all the experiments. For exhaust emissions treatment a typical three-way catalyst was used. The highest hydrocarbon and carbon monoxide engine-out emissions were observed at engine power 2–4 HP. These emissions were decreased as the engine power was increased up to 20 HP. Among the various compounds detected in exhaust emissions, the following ones were monitored at engine and catalyst outlet: methane, hexane, ethylene, acetaldehyde, acetone, benzene, toluene and acetic acid. The concentration of each compound in the catalytic converter effluent was in the range 45–132, 5–12, 10–125, 15–22, 3–7, 3–12, 2–9, 0–6 ppm, respectively. After the required temperature for catalyst operation had been achieved, carbon monoxide tailpipe emissions were dramatically decreased and the observed hydrocarbon conversions were also high. Methane was the most resistant compound to oxidation while ethylene was the most degradable compound over the catalyst. The order from the easiest to the most resistant to oxidation compound was: Alkene>Aromatic>Aldehyde>Ketone>Alkane.