Impact of soot mass on the durability of the SCR washcoat on DPF (SDPF) catalyst

Anand  Lolap, Umicore Autocat USA Inc.

This study investigates the impact of soot mass on the durability of the SCR washcoat on DPF (SDPF) catalyst. Today diesel particulate filters have an approximate soot mass limit defined to ensure the resulting peak temperatures do not negatively impact the substrate integrity. With the advent of SCR on filter technology the soot mass limit in regards to the durability of the catalyst washcoat should also be considered. Here, with an intent to define this level, SCR on filter technology is subjected to numerous cycles of soot loading and standard DPF regeneration conditions on a fuel burner at multiple levels of soot. Elevated levels of soot subject the SPDF to increased thermal exposure and, potentially, higher peak temperatures during soot oxidation. Each catalyst is systematically evaluated for performance impact following the aging procedure and compared to reference “oven aged” samples. Furthermore, a number of catalysts are dynamometer aged in a “Drop-to-Idle” procedure a 3.0L light duty diesel engine to study and compare the impact of these DTI events to the “oven aged” and normal soot regeneration procedure. A detailed analysis of the impact of soot loading on the durability and subsequent NOx performance of an SDPF is presented.