EVAP Canister
WARNING: This page is about a different car, the 2011 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.
The fuel vapor in the sealed fuel tank is led into the EVAP canister which contains activated carbon and the vapor is stored there when the engine is not operating or when refueling to the fuel tank.
For details, refer to "EVAPORATIVE EMISSION SYSTEM : SYSTEM DESCRIPTION ".