A review of the literature of selective catalytic reduction catalysts integrated into diesel particulate filters

Combining the functions of selective catalytic reduction with the diesel particulate filter provides the opportunity in light- to heavy-duty applications for design and packaging flexibility, improved thermal management and reduction of the aftertreatment system volume, mass and cost. This integration can be achieved by washcoating the selective catalytic reduction catalyst on and/or in the diesel particulate filter substrate wall. With packaging flexibility and closer placement of the selective catalytic reduction system to the engine, the aftertreatment system can achieve faster light-off and can operate at higher temperatures. Despite these advantages, there are many challenges associated with the integrated selective catalytic reduction-in-diesel particulate filter technology. This review provides a comparative analysis of the advantages and limitations of the selective catalytic reduction-in-diesel particulate filter technology based on the published literature to date. It summarizes the significant accomplishments for selective catalytic reduction-in-diesel particulate filter technology research and development, including optimization and performance characterization studies based on experimental and modeling effort and the needs for future research and development.