The Effects of Flow-through Type Oxidation Catalysts on the Particulate Reduction of 1990's Diesel Engines

The reduction behavior of diesel particulate and SOF by flow-through type oxidation catalysts was investigated under steady and dynamic engine conditions using a current fuel (S content:0.38 wt%) and a low sulfur fuel (S content:0.04 wt%). Each catalyst gave 40 - 90% SOF reduction at exhaust gas temperatures between 100°C to 500°C. This SOF reduction behavior is explained as follows. SOF is adsorbed or adhered on the catalyst surface at the lower temperatures and is decomposed at the higher temperatures.

Pt only load catalyst which has high SO2 oxidation ability resulted in a low total particulate reduction due to high sulfate formation at higher temperatures even when the low sulfur fuel was used. It has been shown that flow-through type oxidation catalyst with low SO2 oxidation ability will offer a practical exhaust gas treatment method for 1990's improved diesel engines. 50 - 60% SOF reduction and 40 - 50% total particulate reduction has been proved to be possible.