Aftertreatment heat management by controlled exhaust gas recirculation with variable co-current flow upstream of first catalyst

An exhaust system of an engine, comprising:

• an aftertreatment device comprising a first catalyst upstream of a second catalyst relative to a direction of exhaust gas flow;
• a diverter valve arranged in an inlet of the aftertreatment device, the diverter valve configured to move to a first position and a second position;
• a recirculation passage configured to flow exhaust gas from downstream of the aftertreatment device to the inlet of the aftertreatment device, the recirculation passage comprising a compressor upstream of a recirculation valve, and an injector downstream of the recirculation valve;
• and
• a controller with computer-readable instructions stored on memory thereof that when executed cause the controller to:
• adjust the diverter valve to the first position in response to a temperature of the first catalyst being greater than or equal to a light-off temperature;
• and
• adjust the diverter valve to the second position in response to the temperature of the first catalyst being less than the light-off temperature.