Narrow speed range diesel-powered engine system w/ aftertreatment devices

A method of operating an exhaust aftertreatment system for a vehicle, comprising:

• removing NOx from the vehicle's engine exhaust using an aftertreatment system comprising a NOx adsorber-catalyst;
• from time-to-time, regenerating to remove NOx from the NOx adsorber-catalyst;
• and
• from time-to-time, regenerating to remove SOx from the NOx adsorber-catalyst;
• wherein one or more parameters for one or both types of regeneration varies, whereby the saturation of NOx and/or SOx to which the NOx adsorber-catalyst is reduced by regeneration is lower when an operating state makes the NOx adsorber-catalyst otherwise less effective or places a greater demand for conversion efficiency on the NOx adsorber-catalyst;
• wherein the operating state relates to one of a vehicle operating mode, a degree of irreversible poisoning or loss of activity in the NOx adsorber-catalyst, a temperature of the NOx adsorber-catalyst.

A method of operating an exhaust aftertreatment system for a vehicle, comprising:

• removing NOx from the engine exhaust using an exhaust aftertreatment system comprising a NOx adsorber-catalyst;
• from time-to-time, denitrating the NOx adsorber-catalyst;
• from time-to-time, desulfating the NOx adsorber-catalyst;
• desulfating according to a first criteria when engine power demands are not in a peak range;
• desulfating according to a second, more stringent criteria, when engine power demands are in a peak range;
• whereby a degree of sulfur poisoning that remains at the end of a desulfation is lower when engine power demands are in a peak range than it is otherwise.