Gas phase olefin polymerizations using dual donor ziegler-natta catalyst systems

A method for producing gas phase and a piston type reactor, utilizing a halogenated magnesium with the component and an aluminium component is at least one group donor electronic component catalyst system, wherein, wherein the first group donor component, on the water into the axial blowing position is added to a transition metal component to the reactor, and at least a second group donor components according to the first group donor every component with the axial downstream of the reactor.