New Catalytic Solutions for Tightening Emission Standards

To limit problems created by exhaust gas emissions, governments worldwide are gradually introducing more stringent emission standards. To meet new limits, engines as well as exhaust gas after-treatment systems must be improved. The large population of two-stroke engines is a serious problem in many countries, specially in South East Asia. Two-stroke engines create about hundred times higher hydrocarbon and carbon monoxide emissions compared to that of a modern car. However, with a small efficient converter more than half of the emissions can be eliminated, this being the most economic and effective way of reducing emissions from two-stroke engines. In India emission standards are more stringent for CO than for hydrocarbons as compared to the norms in Taiwan and Europe etc. Therefore, the selectivity of the converter should be different to that of a three-way unit. The lack of oxygen in the exhaust gas of a two-stroke engine limits the reaction rate and, for that reason, reactions with water play an important role. Water-gas shift reaction should be favoured instead of steam reforming reaction. The new, more CO selective washcoat is presented in this paper.