Secondary nanoparticle emissions during diesel particulate trap regeneration

Abstract

Two nanostructured mixed oxide catalysts (the CoCr2O4 spinel and the LiCrO2 delafossite) have been recently developed for diesel soot combustion. The catalysts have been deposited via in situ combustion synthesis over SiC wallflow trap by CTI (Salindres, F). Bench tests proved that, after soot loading, both the developed traps enable a faster and more complete regeneration at 550 °C than the non-catalysed trap. However, a specific study on the particles distribution after the SiC trap, carried out via SMPS analysis, showed that secondary nanoparticles (<20 nm) are emitted during the regeneration promoted by the highly-active CoCr2O4 catalytic trap, as opposed to the LiCrO2-catalysed and the virgin counter parts. This phenomenon has been investigated vs. the regeneration temperature and some sampling conditions so as to draw preliminary indications on the nature of these undesired particles.