A model in aftertreatment

A look at 1-D numerical models, based on chemical kinetics derived for real-world catalysts, for a vanadium oxide ammonia SCR catalyst and a PGM-based DOC.

Engine emissions in off-highway applications have been regulated since the 1990s. Increasingly stringent emissions regulations are the major drivers in engine development, and successive generations of machines are defined by the changes in engine emissions levels. Current engines emit 90% less NOx and particulate matter (PM) than their unregulated forebears 10 years ago (introduced in 2006 Stage IIIA). This improvement has been achieved without the use of exhaust catalysts.

Going forward, engines must achieve a simultaneous 40% NOx reduction and 90% PM reduction by 2011/3(Stage IIIB) and then a further 80-90% NOx reduction by 2014/5 (Stage IV). This is where the off-highway equipment market will almost certainly require robust exhaust aftertreatment, especially for PM and NOx control.