Internal combustion engine exhaust treatment having a single valve directing exhaust to dual NOx traps

A single valve directs engine exhaust toward alternative NOx traps which are adjacent to either diesel particulate filters or low temperature water gas shift catalysts. Syngas is either provided from a source or by in-line catalytic partial oxidizers which may have diesel oxidation catalysts ahead of them in the flow and which receive fuel from the engine fuel source through nozzles.