Ag Type PM Oxidation Catalyst with Nd Added to Increase Contact Property between PM and Catalyst 2018-01-0328
Honda diesel engine vehicles that go on sale in 2018 will be equipped with a newly developed cDPF. The cDPF was developed on the concept of enhancing the property of contact between PM and the catalyst. It has realized contact property enhancement at the macro, meso, and nano scales.
Durability in the environment of an automobile in use was examined through hydrothermal aging, lean-rich aging, sulfur poisoning, and ash deposition. The results have confirmed that hydrothermal aging is the greatest factor in deterioration. The reason is that Ag sintering diminishes the PM-catalyst contact property. In order to enhance hydrothermal durability, therefore, an examination was made on additives that would inhibit Ag sintering. It was found, as a result, that adding Nd has the effect of enhancing Ag dispersion and inhibiting sintering, yielding an enhancement of approximately 10% in PM oxidation performance after hydrothermal aging.
H2S removal performance, which is a feature of the Ag catalyst, is also maintained at a level equal to or better than the cDPF deployed in 2015. The 2018 after treatment system is compact and does not require placement of a separate catalyst for H2S removal. In addition, it inhibits the rise of temperature above normal by controlling the catalyst coating length.
The superiority of the developed catalyst was also confirmed by its durability in actual operation. It achieved a regeneration time 32% shorter than the cDPF that had been deployed in 2015.
This Ag-type PM oxidation catalyst, which has been named the silver thin-coated DPF, is expected to ameliorate four issues faced with DPF regeneration: (1) Deterioration in fuel consumption; (2) increase in CO and HC emissions; (3) thermal deterioration in upstream oxidation catalyst; and (4) oil dilution.