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The paper reports on the results of a joint research program performed at Rhône-Poulenc and AVL concerning a passive trap system with Cerium (Ce) as a new patented fuel additive in conjunction with an engine management control system to increase the exhaust gas temperature for initiating regeneration under practically all engine application conditions. Investigations were carried out on a 12L DI/TCI HD diesel engine which meets the US94 emission standards. From the work done the most effective combination of the engine control measures has been established as an apprepriate solution to increase the exhaust gas temperature up to 400 deg. C. at minimum penalty with respect to emissions and fuel consumption. Furthemore, the influence of Cerium on engine-out emissions and fuel consumption has been investigated. It could be shown that by using Cerium, the fuel consumption improves on average by about 2 percent.

Exhaust gas recirculation (EGR) has long been used in gasoline and light-duty diesel engines as a NOx reduction tool. Recently imposed emission regulations led several heavy-duty diesel engine manufacturers to adopt EGR as part of their strategy to reduce NOx. The effectiveness of this technology has been widely documented, with NOx reduction in the range of 40 to 50 percent having been recorded. An inevitable consequence of this strategy is an increase in particulate emission, especially if EGR was used in high engine load modes. Selective catalytic reduction (SCR), a method for NOx reduction, is widely used in stationary applications. There is growing interest and activity to apply it to mobile fleets equipped with heavy-duty diesel engines. Results of this work indicate that SCR has the potential to dramatically reduce NOx in diesel exhaust. Reductions greater than 70 percent were reported by several including the Institute's previous work (SAE Paper No. 1999-01-3564).