An exhaust gas recirculation (EGR) system for an internal combustion engine having dedicated EGR and operating at a lean air-fuel ratio. In such engines, one or more cylinders is operable as a dedicated EGR cylinder, such that all of the exhaust produced by the dedicated EGR cylinder(s) may be recirculated to the engine's main (non dedicated) cylinders. Because the engine is lean burn, its exhaust aftertreatment system has a NOx-reducing device. An EGR loop is configured to recirculate EGR from the dedicated EGR cylinder(s) to the engine's intake manifold. A diversion line connects the EGR loop to the exhaust aftertreatment system, thereby delivering EGR as syngas for the NOx-reducing device. The syngas is used either directly as a reductant or to a catalyst that reduces the syngas to ammonia for use as a reductant.
Charles E. Roberts Jr.; Cary A. Henry