PM Control with Low NO2 Tailpipe Emissions by Systems with Non-PGM Catalyzed DPF for Passive Soot Regeneration

Non-PGM catalyst containing base metal mixed oxide (BMMO) supported on rare earth mixed oxide (REMO) had been evaluated by various methods for soot-oxidation activity. Thermo-gravimetric/Differential Thermal Analysis (TG/DTA) experiments and synthetic gas bench activity tests showed that the catalyst was able to oxidize soot at temperatures significantly lower than soot combustion temperature leading to a conclusion that soot was oxidized via direct reaction with active species of the catalyst surface. It had been shown that low-temperature soot oxidation occurred with and without NO

present in the reaction gas. Evaluation on engine benches of the BMMO catalyst coated on diesel particulate filters (DPF) confirmed low-temperature soot oxidation in exhaust gas with low NO₂ concentration and a possibility of cost-efficient diesel exhaust aftertreatment system without increasing tailpipe NO₂ content.