Patent ID: 8178050

Claim:
A process for introducing a catalyst powder into a polymerization reactor comprising: a) metering the catalyst powder by means of a rotary valve comprising a stator, a rotor and a sealing means comprising a double sequence of sealing rings and arranged between said stator and said rotor; b) transferring a metered amount of catalyst powder from said rotary valve to a polymerization reactor; c) feeding a flushing compound in at least one internal conduit arranged in the rotor of said rotary valve; and d) flushing the catalyst powder away from said sealing means, wherein the catalyst powder is selected from: (i) a Phillips catalyst based on a chromium oxide supported on a refractory oxide, (ii) a Ziegler-Natta catalyst comprising a titanium tetrachloride compound supported on a magnesium chloride, or (iii) a catalyst powder comprising at least two different catalyst components, the first component being a polymerization catalyst based on a monocyclopentadienyl complex of a metal of groups 4-6 of the Periodic Table, and the second component being a polymerization catalyst based on an iron component having a tridentate ligand.