Preparation and characterization of porous cordierite pellets and use as a diesel particulate filter

This paper discusses the preparation and characterization of porous pellet filters for a diesel particulate filter (DPF). The process for creating the porous ceramic pellets was developed using simple gelcasting and a bubble-in-water-in-oil type of pseudo-double-emulsion. The pellets, consisting of a foamed cordierite suspension, were dispersed and consolidated in spherical shapes in liquid paraffin as gelation progressed, and were prepared by a conventional mechanical foaming method combined with gelcasting. In comparison with a wall-flow filter, the pellet filter has the advantages of being free of cracks during regeneration and having a flexible shape. Experiments were conducted in a test simulation of diesel engine exhaust conditions. Pressure drop and particle loading rate were compared using two pellet filters having porosities of 70% and 0%, respectively. Regeneration capability was also tested. The filter which mixed 1 and 2 mm pellets demonstrated feasibility as a DPF.