Particulate Matter, Formation, Composition and Dangers

The second example presented in the current chapter also pertains to the use of catalytic aftertreatment of vehicle exhausts. This example is somewhat different in that there are not material combinations per se but rather we attempted to use one component of a multi component composite to carry out two tasks of interest rather than a single task. 

The applications involved are NOx trapping (as discussed above in Section 1.2.1) and Particulate Matter (PM) combustion (discussed in the following). 

PM - perhaps the most characteristic emission of diesel emissions -is responsible for the black smoke traditionally associated with diesel-powered vehicles. Diesel Engine Generated particles are subject to diesel emission regulations worldwide and, along with NOx, have become the current focus in diesel emission control technology. 

Carbonaceous PM represents the tiny subdivisions of solid/liquid fraction emitted during combustion in a compression ignition engine. 

PM diameters range from less than 10 nm to 100 pm. The notation PM refers to particles of 10 pm and less, and PM refers to particles less than 2.5 pm. Because the method to determine the size and number of particles allows errors, there is no clear cut off size to discriminate between these particles. 

---