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

Abstract

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.

Investigation of Iron Vanadates for Simultaneous Carbon Soot Abatement and NH3-SCR

“…The motivation for the integration of the two reactions is to obtain a reduction of cost and volume of the engine after-treatment system via inclusion of SCR and DPF functionalities into a single entity. Different bi-functional configurations are possible with DPF and SCR catalyst placed in the same housing [7], or with a DPF filter coated with an SCR catalyst formulation [8][9][10].…”

Development of a 2D SCR Catalyst on a Diesel Particulate Filter Model for Design and Control Applications to a Ultra Low NOx Aftertreatment System

“…The location of PM was found to have minimal e↵ect on PM oxidation rate. Also, for the CSF, it was found that PM oxidation rate increased with increase in Pt catalyst loading with 40 g/ft 3 filter having higher PM oxidation rate than 10 g/ft 3 . Pt was found to not catalyze the NO 2 based PM oxidation but instead caused an increase in the NO 2 available in the PM cake by oxidizing NO to NO 2 unlike the catalyst Cu-Ze in the SCRF® which did not oxidize a significant amount of NO to NO 2 .…”

“…Xiaobo Song et al [3] conducted a literature review of papers involved with a SCR catalyst on DPF's related to catalyst design, performance characterization and modeling which was carried out as part of the MTU Diesel Engine Aftertreatment Consortium. The main conclusions from this paper are :…”

“…In order to reduce the packaging volume and cost associated with the CPF and SCR, the selective catalytic reduction catalyst on a filter (SCR-F) has been in R&D over the past 17 years as reviewed by Song. et al [3]. Figure 7.1 shows one system where the CPF and SCR are replaced with an SCR-F similar to the systems described by BASF patents for a SCR catalyst on a DPF [ [54] and 1D SCR [2] models were used to evaluate this system.…”

“…In order to reduce the packaging volume and cost associated with the CPF and SCR, the selective catalytic reduction catalyst on a filter (SCR-F) has been in development over the past 17 years as reviewed by Song. et al [3].…”