Performance and Durability Study of the Particulate Oxidation Catalyst Technology – A Joint Program between SwRI and SwARC, 03-R8095
Inclusive Dates: 09/15/09 03/14/11
Background — The China IV heavy-duty diesel emissions regulation is expected to be implemented beginning in 2012; however, the diesel fuels to be supplied in the Chinese market for the next few years will likely have a sulfur content up to 350 ppm, making them unable to meet the China IV requirement of 50 ppm sulfur content. The high sulfur content of the fuel may affect diesel aftertreatment choices. The particulate oxidation catalyst (POC) technology is claimed to be effective in reducing particulate matter (PM) emissions from the diesel engine and being able to regenerate passively. In addition, it is claimed to be plugging and maintenance free, even if the available diesel fuel has a sulfur content as high as 350 ppm. This project was conducted jointly by SwRI and SwARC to investigate the durability and emissions performance of the POC technology. The durability work was performed at SwARC, and the emissions testing was performed at SwRI. Six other companies joined in the effort by providing test diesel fuels (PetroChina), a 6.7L diesel engine (Cummins), engine oil (SINOPEC), POC systems (Emitec), DOC coating (Umicore) and funding for training of the SwARC staff (CATARC).
Approach — Four POC systems were tested at different durability stages, using three different diesel fuels, with nominal sulfur contents of 50, 150 and 350 ppm, on the MY2007 Cummins ISDe 6.7L engine. The durability testing was conducted over the modified China heavy-duty durability (C-HDD) Cycle at SwARC. Cold-start and hot-start heavy-duty federal test procedure cycles (FTPs), European stationary cycle (ESC) and European transient cycle (ETC) were used for emissions testing of POC-BL, POC-A, POC-B and POC-C at SwRI.
When 50 ppm sulfur diesel fuel was used to age POC-A to two different stages, i.e., 320 hours and 570 hours, it demonstrated PM reduction efficiencies in the range of 53.4 to 82.9 percent, over the cold- and hot-start FTP, ESC and ETC cycles.
When aged to 250 hours using the 150 ppm sulfur diesel, POC-B showed a negative PM reduction efficiency over the ESC tests, meaning that it increased tailpipe PM emissions as compared to engine-out.
An improved DOC formulation may tolerate fuel sulfur content of up to 350ppm. After it was aged for 250 hours using the 350 ppm sulfur diesel, POC-C (with an improved DOC formulation) showed impressive PM reduction efficiencies, 77.4 percent over the cold-start FTP test, an average of 75.9 percent for two hot-start FTP tests, an average of 71.3 percent for three ESC tests, and an average of 73.7 percent for three ETC tests.
The results from this project show that the POC system with the improved DOC formulation has the potential to be applied for PM emission control from HD diesel engines to meet China IV regulations. However, it should be understood that integrating the POC system with the engine is extremely important, and on-board diagnosis (OBD) is required to meet the China IV requirements.