Microwave Susceptible Catalytic Diesel Particulate Filter

Abstract

The diesel internal combustion engine is one of the most environmentally-friendly vehicle devices, because it emits less carbon dioxide and is more fuel efficient than the universal gasoline stoichiometric engine. However, considerable challenges still exist regarding the emission control of particulate matter (PM), commonly known as soot, emitted by the diesel combustion process. These ultrafine particles, which have aerodynamic diameters of less than 2.5 ?m (PM2.5), are problematic as they can cause serious respiratory diseases, including lung cancer and chronic obstructive pulmonary disease. Various filters are commonly used for soot abatement in diesel exhaust, while catalytic oxidation is preferable to intensify burning of soot trapped in filters. The diesel particulate filters (DPFs) are the most important technologies to maintain soot emissions under EU regulations, consisting in alternately plugged parallel square channels, so that the exhaust gases are forced to flow through the porous inner walls: in this way the particles are collected on the surface and in the porosity of the channel walls, progressively blocking the pores. Since the pressure loss increases by the formation of a thick soot cake as the PM is accumulated, the DPF needs to be periodically regenerated by burning off the accumulated soot. The results of our previous deposition and on-line regeneration tests on uncatalysed and Copper-Ferrite catalysed DPF, showed that the simultaneous use of a catalyst properly formulated and microwaves during the regeneration step at lower gas flow rate, allows to reduce the energy supplied and the regeneration time than that required for the uncatalysed filter. Starting by these very promising results, the objectives of this work are to increase the active species load simultaneously modifying the porosimetric characteristics of the support, in order to simultaneously further reduce the PM oxidation temperature and keep low the pressure drop.