PROCESS CONTROL FOR LONG CHAIN BRANCHING CONTROL IN POLYETHYLENE PRODUCTION

摘要

Polymerization process control methods for making polyethylene are provided. The process control methods include performing a polymerization reaction in a polymerization reactor to produce the polyethylene, where ethylene, and optionally one or more comonomers, in the polymerization reaction is catalyzed by an electron donor-free Ziegler-Natta catalyst and an alkyl aluminum co-catalyst. A melt flow ratio (I21/I2) of the polyethylene removed from the polymerization reactor is measured and an amount of long chain branching (LCB) of the polyethylene from the polymerization reactor is controlled by adjusting a weight concentration of the alkyl aluminum co-catalyst present in the polymerization reactor. In addition, an electron donor-free Ziegler-Natta catalyst productivity of the polyethylene being produced in the polymerization reactor is measured from which the amount of LCB of the polyethylene from the polymerization reactor is determined using the measured electron donor-free Ziegler-Natta catalyst productivity and a predetermined relationship between the electron donor-free Ziegler-Natta catalyst productivity and the LCB.

主权项

1. A polymerization process control method, comprising:
performing a polymerization reaction in a polymerization reactor to produce polyethylene, wherein the polymerization reaction is catalyzed by an electron donor-free Ziegler-Natta catalyst and an alkyl aluminum co-catalyst with ethylene and optionally one or more comonomers to produce the polyethylene; removing a portion of the polyethylene from the polymerization reactor; measuring a melt flow ratio (I21/I2) of the polyethylene removed from the polymerization reactor to determine the amount of long chain branching (LCB) using a predetermined relationship between the melt flow ratio (I21/I2) and the LCB; and controlling an amount of long chain branching (LCB) of the polyethylene from the polymerization reactor by adjusting a weight concentration of the alkyl aluminum co-catalyst present in the polymerization reactor.