Catalytic aftertreatment of particulate matter

Report, 2017

Particulate emissions cause millions of premature deaths every year and emissions from road transportation makes a significant contribution. The last years more stringent emissions regulations will enforce the implementation of particulate filters and much of the health issues can be significantly reduced. Since the efficiency of the filter depends on a range of parameters and since it also brings an increased fuel penalty from the increased pressure drop, it is very important to understand the different mechanisms in the filter. Through this understanding, it becomes possible to eliminate the negative heath issues from particulate emissions with a minimal fuel penalty and thereby also lowering CO2 emissions. The particulate emissions, which mainly consists of soot (graphitized carbon), is oxidized in the filter often using catalysis. This project has been focusing on experiments both in lab scale and connected to full scale (engine bench testing). The project has also developed a methodology to enable further research within the area. The project has demonstrated that the oxidation mechanisms depends of more factors than what is usually considered in the automotive industry. These factors include the previous history of the soot, interaction effects of gas phase components and the sot surface as well as mass transfer limitations. In order to improve the performance of particulate reduction from road vehicles, improved mathematical models are needed. This becomes possible by including the phenomena demonstrated in this project. More work is needed until validated models executable in realtime is ready, but by bridging knowledge between lab scale and full scale, this work will be more efficient.