Car Exhaust Pollution Control

Over the past twenty years catalysts containing platinum group metals have become the preferred means of limiting the polluting emissions of carbon monoxide, hydrocarbons and nitrogen oxides from motor vehicles. However, from time to time methods of exhaust control are proposed which appear to offer a viable alternative to autocatalysts. Europe has been slow to adopt emission control standards for vehicles which is, perhaps, surprising bearing in mind that European catalyst manufacturers have been producing autocatalysts and European car producers have been fitting them to vehicles destined for the U.S. and Japanese markets for over fourteen years. This article gives the background to the suggested alternatives, which are in the main different approaches to lean burn operation, and to other engine based controls. It explains why, for the foreseeable future, a platinum-containing autocatalyst will still be required to ensure that the cleanest possible exhaust is emitted under all driving conditions.