NOVELTY - A nitrogen oxides adsorber used to remove nitrogen oxides from exhaust gases generated during combustion of an engine fuel is regenerated by reforming a first quantity of a gaseous hydrocarbon to generate hydrogen; creating a regeneration mix comprising the hydrogen and a quantity of the exhaust gases with reduced oxygen concentration; and directing the regeneration mix into the adsorber.    USE - For regenerating an NOx adsorber used to remove NOx from exhaust gases generated by combustion of a fuel in a combustion chamber of an internal combustion engine.    ADVANTAGE - The invention manages the problems associated with the NOx levels when gaseous fuels are used.    DETAILED DESCRIPTION - Regeneration of a nitrogen oxides (NOx) adsorber used to remove NOx from exhaust gases generated by combustion of a fuel in a combustion chamber of an internal combustion engine, includes directing the exhaust gases from the combustion chamber into an exhaust line, where the NOx adsorber is disposed in the exhaust line; reforming a first quantity of a gaseous hydrocarbon to generate hydrogen; creating a regeneration mix comprising a quantity of the exhaust gases where its oxygen concentration has been reduced, and the hydrogen; and directing the regeneration mix into the NOx adsorber. An INDEPENDENT CLAIM is also included for an aftertreatment system for treating NOx within the exhaust gases, comprising the exhaust line (10, 27) connected to carry exhaust gases from the combustion chamber to the NOx adsorber (46) disposed in the exhaust line; an oxidizer capable of reducing the oxygen concentration of the first quantity of the exhaust gases; a reformer (44) capable of using a gaseous hydrocarbon to generate hydrogen; a first gas line connected to carry the first quantity of the gaseous hydrocarbon from a gaseous hydrocarbon store to the reformer; and a regeneration line connected to carry the regeneration mix to the exhaust line upstream of the NOx adsorber.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic of an NOx management system.    Exhaust line (10, 27)    By-pass line (12)    Hydrocarbon store (36)    Oxidation catalyst (42)    Reformer (44)    NOx adsorber (46)