A diesel particulate filter (DPF) removes particulate matter from diesel exhaust by physical filtration. Many filter types are available but the most common type is a ceramic (cordierite or silicon carbide) honeycomb monolith.
The structure is like an emissions catalyst substrate but with the channels blocked at alternate ends. The exhaust gases must therefore flow through the walls between the channels and the particulate matter (PM) is deposited on the walls.
The filtration efficiencies of diesel particulate filters is >99% for solid matter. Since diesel particulate matter has a non-solid portion, the total efficiency for this is lower than this >90%.
All particulate filter systems include some means of