Diesel Emission Control:Catalytic Filters for Particulate Removal

The European diesel engine industry represents a vital sector across the Continent, with more than 2 million direct work positions and a turnover of over 400 billion Euro. Diesel engines provide large paybacks to society since they are extensively used to transport goods, services and people. In recent years increasing attention has been paid to the emissions from diesel engines which, like gasoline engine emissions, include carbon monoxide (CO), hydrocarbons (HC) and oxides of nitrogen (NOx). Diesel engines also produce significant levels of particulate matter (PM), which consists mostly of carbonaceous soot and a soluble organic fraction (SOF) of hydrocarbons that have condensed on the soot. Meeting the emission levels imposed for NOx and PM by legislation (Euro IV in 2005 and, in the 2008 perspective, Euro V) requires the development of a number of critical technologies to fulfill these very stringent emission limits (e.g. 0.005 g/km for PM). This review is focused on these innovative technologies with special reference to catalytic traps for diesel particulate removal.