Performance Evaluation Study to Optimize the NOx Conversion Efficiency of SDPF Catalyst for BS6 RDE/OBD2 Engine Application

To meet future emission levels, the automotive industry is trying to reduce tailpipe emissions through both possible pathways, i.e. emission from engines as well as and the development of novel catalytic emission control concepts. The present study will focus on the close coupled SCR on Filter commonly known as SDPF which is a main pathway to reduce NOx along with particulate mass and number for light duty passenger cars and sport utility vehicles for BS 6 RDE/OBD 2 and future legislation like BS-7. The SDPF is a challenging technology as it is critical component in exhaust after treatment system involving in NOx and PM/PN reductions hence careful optimization of this technology is necessary in terms of space velocity requirements, temperature, feed NOx emission levels, particulate mass and ash holding capacities, NH₃ storage on the SDPF, and back pressure.

With BS6 RDE having extremely challenging conformity factor (CF) for NOx equals to 1.43, the SDPF design & optimization is high on importance. Tools such as simulation, synthetic gas bench and engine bench testing and vehicle testing, in conjunction with each other can play critical role in optimal design of the SDPF by enabling the assessment of catalyst performance with different input conditions before the actual hardware testing.

Umicore always strive to design the catalyst not only for legislative cycles but ensure that these systems work well till the end of the useful life. This paper presents a joint study between Umicore and OEM (Original Equipment Manufacturer) for analyzing the performance of a 1.5L engine volume SDPF catalyst for a vehicle application. Initially catalyst parameter evaluation was done on synthetic gas bench (SGB). Further, a systematic approach is followed to understand the effect of feed NO₂/NOx ratio, catalyst volume, inlet temperature and the feed NH₃/NOx ratio on the NOx conversion efficiency of the catalyst by using a model-based study. The benefit of using an optimal urea dosing strategy over a simplistic dosing strategy for maximum NOx conversion is also demonstrated.