The present invention relates to propylene
polymerization process in a bulk loop reactor, and particularly to propylene
polymerization process for polymerizing commercial quantities of
polypropylene in a bulk loop reactor by sequentially introducing Ziegler-
Natta and
metallocene catalyst systems into the bulk loop reactor. In one embodiment, separate catalyst mixing systems are used to introduce a quantity of
metallocene catalyst and Ziegler-
Natta catalyst into the bulk loop reactor. The frequency rate at which the quantity of
metallocene catalyst is introduced into the bulk loop reactor may be higher than the frequency rate at which the quantity of Ziegler-
Natta catalyst is introduced. In another embodiment, a method of polymerizing propylene in a bulk loop reactor is provided which includes contacting a quantity of supported metallocene catalyst with a first quantity of
scavenger, such as TEAL and or TIBAL, prior to injecting the supported metallocene catalyst into the bulk loop reactor and contacting a quantity of Ziegler-Natta catalyst
system with a second quantity of
scavenger prior to injecting the Ziegler-Natta catalyst
system into the bulk loop reactor, wherein the second quantity of
scavenger is greater that the first quantity of scavenger. In another embodiment, a method of contacting a flow of metallocene with a flow of propylene is provided. This method includes directing the flow of metallocene towards a junction, directing the flow of propylene towards the junction and maintaining a portion of the flow of metallocene separate from a portion of the flow propylene within a portion of the junction downstream of the flow of propylene into the junction. In another embodiment, a method of introducing a quantity of antifouling agent into a catalyst mixing
system is provided. In this embodiment a portion of the antifouling agent is introduced at or downstream of a point of contact of a
stream of propylene with a
stream of catalyst. The antifouling agent may be a member, alone or in combination with other members, selected from the group consisting of Stadis 450
Conductivity Improver, Synperonic antifouling agent, and Pluronic antifouling agent.