The loading comes in the wake of removed economic sanctions on Tehran's nuclear agenda.
The fully-Swedish-owned 49,000-ton vessel is the biggest tanker for methanol transfer that has ever called at the port.
Previously the consignments were delivered by smaller tankers.
Stenaweco Impulse is the newest vessel owned by Stena Weco, a joint venture between Swedish Stena Bulk and Danish Weco shipping for the transport of vegetable oils, chemicals and petroleum products.