This presentation will review the field of vehicle emission control with the intent of highlighting representative studies that illustrate the state-of-the-art. First, the author reviews regulatory requirements and general engine technology approaches for light-duty and heavy-duty applications. The presentation then reviews: diesel particulate filter (DPF) technology, covering regeneration strategies, filter properties, and durability and maintenance; NOx control by SCR (selective catalytic reduction), and diesel oxidation catalysts (DOC). The author then summarizes the field of gasoline emission control, with focus on the emerging particle number (PN) regulations in Europe and the California LEVIII regulations in the US.
In general, there is increasing emphasis on fuel economy and CO2 emissions. Biofuels and advanced engine technologies will play a key role. Progress is impressive and studies demonstrate that high-efficiency systems are within reach in all highway vehicle sectors. Engines are making impressive gains, and will increase the options for emission control. Filter technology is focusing on optimization, with work being done on better ways to regenerate the filter and improve system back pressure and durability. SCR NOx control is focusing on low-temperature performance and system control, N2O emissions, and is moving into optimization. DOCs balance HC and CO light-off with NO2 generation, and new formulations are dropping light-off temperatures. Gasoline PN control can largely be accomplished with engine modifications, but gasoline particulate filters are very effective and have minimal adverse effects. The three-way catalyst is continuing its impressive trend towards cost reduction and improved performance.