An active system for regenerating a NOX adsorber and a particulate filter, the system comprising a fuel source, a reformer for generating hydrogen and carbon monoxide in fluid communication with the fuel source, a first valve, a second valve, and a third valve in fluid communication with the reformer, an oxidation catalyst, a NOX adsorber located downstream from the oxidation catalyst, a particulate filter located downstream from the NOX adsorber; and wherein the first valve, the second valve, and the third valve control fluid flow from the reformer to the oxidation catalyst, the NOX adsorber, and the particulate filter.