Abstract: A system and method for regenerating a device in an engine exhaust after-treatment system is provided. To regenerate the device, a syngas stream is introduced into the engine exhaust stream and combusts in the presence of a catalyst in the after-treatment system, raising the temperature. A supplemental liquid fuel stream is then selectively introduced into and is vaporized by the syngas stream to form a combined fuel stream. Combustion of the combined fuel stream with the engine exhaust in the presence of the catalyst further heats the device bringing it to a temperature suitable for regeneration. The catalyst can be upstream of or within the device being regenerated.