Highly Dispersed Ceria for Catalytic Regeneration of Diesel Particulate Filters

The regeneration performance of a diesel particulate filter (DPF) wash-coated with nanometric ceria particles was studied focusing on the effect of the soot-catalyst contact. The pore size distribution of the catalyst-loaded filter did not show significant differences with respect to that of the bare filter. Furthermore, the catalyst was highly dispersed inside the filter walls. The soot load was varied, thus investigating different conditions of sootceria contact. At the lowest soot load explored, the deep penetration of soot particles into the macro-pores of the filter walls and the consequent close touch with the catalyst result in a large fraction of soot burned via catalytic path at low temperatures. At the highest soot load explored, a rather thick soot cake layer is also formed on top of the catalytic walls of the filter. The sook cake is substantially segregated from the catalyst and, as such, is oxidized via thermal path at high temperatures.