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To satisfy China IV emissions regulations, diesel truck manufacturers are striving to meet increasingly stringent Oxides of Nitrogen (NOx) reduction standards. Heavy duty truck manufacturers demand compact urea SCR NOx abatement designs, which integrate injectors, NOx sensors and necessary components on SCR can in order to save packaging space and system cost. To achieve this goal, aftertreatment systems need to be engineered to achieve high conversion efficiencies, low back pressure, no urea deposit risks and good mechanical durability. Initially, a baseline Euro IV Urea SCR system is evaluated because of concerns on severe deposit formation. Systematic enhancements of the design have been performed to enable it to meet multiple performance targets, including emission reduction efficiency and low urea deposit risks via improved reagent mixing, evaporation, and distribution. Acoustic performance has been improved from the baseline system as well.

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.